G2Cdb::Gene report

Gene id
Gene symbol
Hras1 (MGI)
Mus musculus
Harvey rat sarcoma virus oncogene 1
G00000031 (Homo sapiens)

Databases (9)

Curated Gene
OTTMUSG00000016471 (Vega mouse gene)
ENSMUSG00000025499 (Ensembl mouse gene)
15461 (Entrez Gene)
61 (G2Cdb plasticity & disease)
Gene Expression
NM_008284 (Allen Brain Atlas)
15461 (Genepaint)
190020 (OMIM)
Marker Symbol
MGI:96224 (MGI)
Protein Sequence
Q61411 (UniProt)

Synonyms (7)

  • H-ras
  • Ha-ras
  • Harvey-ras
  • Hras-1
  • c-H-ras
  • c-rasHa
  • ras

Alleles (3)

Allele Name Type Description Literature
A00000005 H-RAS ko knockout Hras1 (H-ras) knockout  

Literature (249)

Pubmed - g2c

  • NMDA receptor activation dephosphorylates AMPA receptor glutamate receptor 1 subunits at threonine 840.

    Delgado JY, Coba M, Anderson CN, Thompson KR, Gray EE, Heusner CL, Martin KC, Grant SG and O'Dell TJ

    Interdepartmental PhD Program for Neuroscience, University of California, Los Angeles, 90095, USA.

    Phosphorylation-dependent changes in AMPA receptor function have a crucial role in activity-dependent forms of synaptic plasticity such as long-term potentiation (LTP) and long-term depression (LTD). Although three previously identified phosphorylation sites in AMPA receptor glutamate receptor 1 (GluR1) subunits (S818, S831, and S845) appear to have important roles in LTP and LTD, little is known about the role of other putative phosphorylation sites in GluR1. Here, we describe the characterization of a recently identified phosphorylation site in GluR1 at threonine 840. The results of in vivo and in vitro phosphorylation assays suggest that T840 is not a substrate for protein kinases known to phosphorylate GluR1 at previously identified phosphorylation sites, such as protein kinase A, protein kinase C, and calcium/calmodulin-dependent kinase II. Instead, in vitro phosphorylation assays suggest that T840 is a substrate for p70S6 kinase. Although LTP-inducing patterns of synaptic stimulation had no effect on GluR1 phosphorylation at T840 in the hippocampal CA1 region, bath application of NMDA induced a strong, protein phosphatase 1- and/or 2A-mediated decrease in T840 phosphorylation. Moreover, GluR1 phosphorylation at T840 was transiently decreased by a chemical LTD induction protocol that induced a short-term depression of synaptic strength and persistently decreased by a chemical LTD induction protocol that induced a lasting depression of synaptic transmission. Together, our results show that GluR1 phosphorylation at T840 is regulated by NMDA receptor activation and suggest that decreases in GluR1 phosphorylation at T840 may have a role in LTD.

    Funded by: NIMH NIH HHS: R01 MH060919, R01 MH060919-06A1; Wellcome Trust: 077155

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2007;27;48;13210-21

  • SynGAP regulates ERK/MAPK signaling, synaptic plasticity, and learning in the complex with postsynaptic density 95 and NMDA receptor.

    Komiyama NH, Watabe AM, Carlisle HJ, Porter K, Charlesworth P, Monti J, Strathdee DJ, O'Carroll CM, Martin SJ, Morris RG, O'Dell TJ and Grant SG

    Division of Neuroscience, University of Edinburgh, Edinburgh EH8-9JZ, United Kingdom.

    At excitatory synapses, the postsynaptic scaffolding protein postsynaptic density 95 (PSD-95) couples NMDA receptors (NMDARs) to the Ras GTPase-activating protein SynGAP. The close association of SynGAP and NMDARs suggests that SynGAP may have an important role in NMDAR-dependent activation of Ras signaling pathways, such as the MAP kinase pathway, and in synaptic plasticity. To explore this issue, we examined long-term potentiation (LTP), p42 MAPK (ERK2) signaling, and spatial learning in mice with a heterozygous null mutation of the SynGAP gene (SynGAP(-/+)). In SynGAP(-/+) mutant mice, the induction of LTP in the hippocampal CA1 region was strongly reduced in the absence of any detectable alteration in basal synaptic transmission and NMDAR-mediated synaptic currents. Although basal levels of activated ERK2 were elevated in hippocampal extracts from SynGAP(-/+) mice, NMDAR stimulation still induced a robust increase in ERK activation in slices from SynGAP(-/+) mice. Thus, although SynGAP may regulate the ERK pathway, its role in LTP most likely involves additional downstream targets. Consistent with this, the amount of potentiation induced by stimulation protocols that induce an ERK-independent form of LTP were also significantly reduced in slices from SynGAP(-/+) mice. An elevation of basal phospho-ERK2 levels and LTP deficits were also observed in SynGAP(-/+)/H-Ras(-)/- double mutants, suggesting that SynGAP may normally regulate Ras isoforms other than H-Ras. A comparison of SynGAP and PSD-95 mutants suggests that PSD-95 couples NMDARs to multiple downstream signaling pathways with very different roles in LTP and learning.

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2002;22;22;9721-32

Pubmed - other

  • Activated Ras requires autophagy to maintain oxidative metabolism and tumorigenesis.

    Guo JY, Chen HY, Mathew R, Fan J, Strohecker AM, Karsli-Uzunbas G, Kamphorst JJ, Chen G, Lemons JM, Karantza V, Coller HA, Dipaola RS, Gelinas C, Rabinowitz JD and White E

    The Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, USA.

    Autophagy is a catabolic pathway used by cells to support metabolism in response to starvation and to clear damaged proteins and organelles in response to stress. We report here that expression of a H-ras(V12) or K-ras(V12) oncogene up-regulates basal autophagy, which is required for tumor cell survival in starvation and in tumorigenesis. In Ras-expressing cells, defective autophagosome formation or cargo delivery causes accumulation of abnormal mitochondria and reduced oxygen consumption. Autophagy defects also lead to tricarboxylic acid (TCA) cycle metabolite and energy depletion in starvation. As mitochondria sustain viability of Ras-expressing cells in starvation, autophagy is required to maintain the pool of functional mitochondria necessary to support growth of Ras-driven tumors. Human cancer cell lines bearing activating mutations in Ras commonly have high levels of basal autophagy, and, in a subset of these, down-regulating the expression of essential autophagy proteins impaired cell growth. As cancers with Ras mutations have a poor prognosis, this "autophagy addiction" suggests that targeting autophagy and mitochondrial metabolism are valuable new approaches to treat these aggressive cancers.

    Funded by: NCI NIH HHS: P30 CA072720, R00 CA133181, R00 CA133181-03, R01 CA130893, R37 CA053370, R37 CA53370, RC1 CA147961

    Genes & development 2011;25;5;460-70

  • Thyrotrophin receptor signaling dependence of Braf-induced thyroid tumor initiation in mice.

    Franco AT, Malaguarnera R, Refetoff S, Liao XH, Lundsmith E, Kimura S, Pritchard C, Marais R, Davies TF, Weinstein LS, Chen M, Rosen N, Ghossein R, Knauf JA and Fagin JA

    Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.

    Mutations of BRAF are found in ∼45% of papillary thyroid cancers and are enriched in tumors with more aggressive properties. We developed mice with a thyroid-specific knock-in of oncogenic Braf (LSL-Braf(V600E)/TPO-Cre) to explore the role of endogenous expression of this oncoprotein on tumor initiation and progression. In contrast to other Braf-induced mouse models of tumorigenesis (i.e., melanomas and lung), in which knock-in of Braf(V600E) induces mostly benign lesions, Braf-expressing thyrocytes become transformed and progress to invasive carcinomas with a very short latency, a process that is dampened by treatment with an allosteric MEK inhibitor. These mice also become profoundly hypothyroid due to deregulation of genes involved in thyroid hormone biosynthesis and consequently have high TSH levels. To determine whether TSH signaling cooperates with oncogenic Braf in this process, we first crossed LSL-Braf(V600E)/TPO-Cre with TshR knockout mice. Although oncogenic Braf was appropriately activated in thyroid follicular cells of these mice, they had a lower mitotic index and were not transformed. Thyroid-specific deletion of the Gsα gene in LSL-Braf(V600E)/TPO-Cre/Gnas-E1(fl/fl) mice also resulted in an attenuated cancer phenotype, indicating that the cooperation of TshR with oncogenic Braf is mediated in part by cAMP signaling. Once tumors were established in mice with wild-type TshR, suppression of TSH did not revert the phenotype. These data demonstrate the key role of TSH signaling in Braf-induced papillary thyroid cancer initiation and provide experimental support for recent observations in humans pointing to a strong association between TSH levels and thyroid cancer incidence.

    Funded by: Cancer Research UK: 13083; Intramural NIH HHS; NCI NIH HHS: CA50706, CA72597, F32 CA136178, F32CA136178, P30 CA008748, P30 CA08748, P50 CA092629, P50-CA92629, R01 CA050706, R01 CA072597, R24 CA083084, R24 CA83084; NIDDK NIH HHS: DK17050

    Proceedings of the National Academy of Sciences of the United States of America 2011;108;4;1615-20

  • A high-resolution anatomical atlas of the transcriptome in the mouse embryo.

    Diez-Roux G, Banfi S, Sultan M, Geffers L, Anand S, Rozado D, Magen A, Canidio E, Pagani M, Peluso I, Lin-Marq N, Koch M, Bilio M, Cantiello I, Verde R, De Masi C, Bianchi SA, Cicchini J, Perroud E, Mehmeti S, Dagand E, Schrinner S, Nürnberger A, Schmidt K, Metz K, Zwingmann C, Brieske N, Springer C, Hernandez AM, Herzog S, Grabbe F, Sieverding C, Fischer B, Schrader K, Brockmeyer M, Dettmer S, Helbig C, Alunni V, Battaini MA, Mura C, Henrichsen CN, Garcia-Lopez R, Echevarria D, Puelles E, Garcia-Calero E, Kruse S, Uhr M, Kauck C, Feng G, Milyaev N, Ong CK, Kumar L, Lam M, Semple CA, Gyenesei A, Mundlos S, Radelof U, Lehrach H, Sarmientos P, Reymond A, Davidson DR, Dollé P, Antonarakis SE, Yaspo ML, Martinez S, Baldock RA, Eichele G and Ballabio A

    Telethon Institute of Genetics and Medicine, Naples, Italy.

    Ascertaining when and where genes are expressed is of crucial importance to understanding or predicting the physiological role of genes and proteins and how they interact to form the complex networks that underlie organ development and function. It is, therefore, crucial to determine on a genome-wide level, the spatio-temporal gene expression profiles at cellular resolution. This information is provided by colorimetric RNA in situ hybridization that can elucidate expression of genes in their native context and does so at cellular resolution. We generated what is to our knowledge the first genome-wide transcriptome atlas by RNA in situ hybridization of an entire mammalian organism, the developing mouse at embryonic day 14.5. This digital transcriptome atlas, the Eurexpress atlas (http://www.eurexpress.org), consists of a searchable database of annotated images that can be interactively viewed. We generated anatomy-based expression profiles for over 18,000 coding genes and over 400 microRNAs. We identified 1,002 tissue-specific genes that are a source of novel tissue-specific markers for 37 different anatomical structures. The quality and the resolution of the data revealed novel molecular domains for several developing structures, such as the telencephalon, a novel organization for the hypothalamus, and insight on the Wnt network involved in renal epithelial differentiation during kidney development. The digital transcriptome atlas is a powerful resource to determine co-expression of genes, to identify cell populations and lineages, and to identify functional associations between genes relevant to development and disease.

    Funded by: Medical Research Council: MC_U127527203; Telethon: TGM11S03

    PLoS biology 2011;9;1;e1000582

  • The TGF-beta co-receptor endoglin modulates the expression and transforming potential of H-Ras.

    Santibanez JF, Pérez-Gómez E, Fernandez-L A, Garrido-Martin EM, Carnero A, Malumbres M, Vary CP, Quintanilla M and Bernabéu C

    Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC) and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28040 Madrid, Spain.

    Endoglin is a coreceptor for transforming growth factor-β (TGF-β) that acts as a suppressor of malignancy during mouse skin carcinogenesis. Because in this model system H-Ras activation drives tumor initiation and progression, we have assessed the effects of endoglin on the expression of H-Ras in transformed keratinocytes. We found that TGF-β1 increases the expression of H-Ras at both messenger RNA and protein levels. The TGF-β1-induced H-Ras promoter transactivation was Smad4 independent but mediated by the activation of the TGF-β type I receptor ALK5 and the Ras-mitogen-activated protein kinase (MAPK) pathway. Endoglin attenuated stimulation by TGF-β1 of both MAPK signaling activity and H-Ras gene expression. Moreover, endoglin inhibited the Ras/MAPK pathway in transformed epidermal cells containing an H-Ras oncogene, as evidenced by the levels of Ras-guanosine triphosphate, phospho-MAPK kinase (MEK) and phospho-extracellular signal-regulated kinase (ERK) as well as the expression of c-fos, a MAPK downstream target gene. Interestingly, in spindle carcinoma cells, that have a hyperactivated Ras/MAPK pathway, endoglin inhibited ERK phosphorylation without affecting MEK or Ras activity. The mechanism for this effect is unknown but strongly depends on the endoglin extracellular domain. Because the MAPK pathway is a downstream mediator of the transforming potential of Ras, the effect of endoglin on the oncogenic function of H-Ras was assessed. Endoglin inhibited the transforming capacity of H-Ras(Q61K) and H-Ras(G12V) oncogenes in a NIH3T3 focus formation assay. The ability to interfere with the expression and oncogenic potential of H-Ras provides a new face of the suppressor role exhibited by endoglin in H-Ras-driven carcinogenesis.

    Carcinogenesis 2010;31;12;2145-54

  • Silencing the expression of Ras family GTPase homologues decreases inflammation and joint destruction in experimental arthritis.

    de Launay D, Vreijling J, Hartkamp LM, Karpus ON, Abreu JR, van Maanen MA, Sanders ME, Grabiec AM, Hamann J, Ørum H, Vervoordeldonk MJ, Fluiter K, Tak PP and Reedquist KA

    Division of Clinical Immunology and Rheumatology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.

    Changes in the expression and activation status of Ras proteins are thought to contribute to the pathological phenotype of stromal fibroblast-like synoviocytes (FLS) in rheumatoid arthritis, a prototypical immune-mediated inflammatory disease. Broad inhibition of Ras and related proteins has shown protective effects in animal models of arthritis, but each of the Ras family homologues (ie, H-, K-, and N-Ras) makes distinct contributions to cellular activation. We examined the expression of each Ras protein in synovial tissue and FLS obtained from patients with rheumatoid arthritis and other forms of inflammatory arthritis. Each Ras protein was expressed in synovial tissue and cultured FLS. Each homolog was also activated following FLS stimulation with tumor necrosis factor-α or interleukin (IL)-1β. Constitutively active mutants of each Ras protein enhanced IL-1β-induced FLS matrix metalloproteinase-3 production, while only active H-Ras enhanced IL-8 production. Gene silencing demonstrated that each Ras protein contributed to IL-1β-dependent IL-6 production, while H-Ras and N-Ras supported IL-1β-dependent matrix metalloproteinase-3 and IL-8 production, respectively. The overlap in contributions of Ras homologues to FLS activation suggests that broad targeting of Ras GTPases in vivo suppresses global inflammation and joint destruction in arthritis. Consistent with this, simultaneous silencing of H-Ras, K-Ras, and N-Ras expression significantly reduces inflammation and joint destruction in murine collagen-induced arthritis, while specific targeting of N-Ras alone is less effective in providing clinical benefits.

    The American journal of pathology 2010;177;6;3010-24

  • Constitutively active H-ras accelerates multiple forms of plasticity in developing visual cortex.

    Kaneko M, Cheetham CE, Lee YS, Silva AJ, Stryker MP and Fox K

    Department of Physiology and the Keck Center for Integrative Neurosciences, University of California, San Francisco, CA 94143-0444, USA.

    Experience-dependent cortical plasticity has been studied by using loss-of-function methods. Here, we take the complementary approach of using a genetic gain-of-function that enhances plasticity. We show that a constitutively active form of H-ras (H-ras(G12V)), expressed presynaptically at excitatory synapses in mice, accelerates and enhances multiple, mechanistically distinct forms of plasticity in the developing visual cortex. In vivo, H-ras(G12V) not only increased the rate of ocular dominance change in response to monocular deprivation (MD), but also accelerated recovery from deprivation by reverse occlusion. In vitro, H-ras(G12V) expression decreased baseline presynaptic release probability and enhanced presynaptically expressed long-term potentiation (LTP). H-ras(G12V) expression also accelerated the increase following MD in the frequency of miniature excitatory potentials, mirroring accelerated plasticity in vivo. These findings demonstrate accelerated neocortical plasticity, which offers an avenue toward future therapies for many neurological and neuropsychiatric disorders.

    Funded by: Medical Research Council: G0901299; NIMH NIH HHS: P50 MH077972, P50-MH0779720

    Proceedings of the National Academy of Sciences of the United States of America 2010;107;44;19026-31

  • p66(Shc) restrains Ras hyperactivation and suppresses metastatic behavior.

    Ma Z, Liu Z, Wu RF and Terada LS

    Department of Internal Medicine, Division of Pulmonary and Critical Care, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.

    Normal tissue cells survive and proliferate only while anchored to solid substrate. Conversely, transformed cells both survive and proliferate following detachment, having lost attachment context through unclear mechanisms. p66(Shc) is a focal adhesion-associated protein that reports cell attachment through a RhoA-dependent mechanosensory test. We find that human small cell lung cancer (SCLC) cells and mouse Lewis lung carcinoma (LLC), which display aggressive metastatic behavior, lack both p66(Shc) and retinoblastoma (pRB) and bypass anoikis. Re-expression of p66(Shc) in these cells restores anoikis and provides striking protection from metastasis by LLC cells in vivo. Notably, knockdown of p66(Shc) in normal epithelial cells leads to unrestrained Ras activation, preventing anoikis through downstream suppression of RhoA but blocking proliferation in a pRB-dependent manner, thus mimicking oncogenic Ras. Conversely, LLC and SCLC cells display constitutive Ras activation necessary to bypass anoikis, which is reversed by re-expression of p66(Shc). p66(Shc) therefore coordinates Ras-dependent control of proliferation and anchorage sensation, which can be defeated in the evolution of highly metastatic tumors by combined loss of both p66(Shc) and pRB.

    Funded by: NHLBI NIH HHS: R01 HL061897, R01 HL067256, R01 HL067256-09, R01-HL061897, R01-HL067256

    Oncogene 2010;29;41;5559-67

  • Effect of Ha-rasval12 on nm23 expression, tumor formation and metastasis of the transformants, and immunomodulation in tumor-bearing mice.

    Hsieh CC, Wu SY, Lan SH, Weng TY, Tsai Y and Liu HS

    1Department of Animal Science and Biotechnology, Tunghai University, Taichung, Taiwan, ROC.

    Overexpression of the Ha-ras(val12) oncogene has frequently been detected in primary and metastatic carcinomas. NM23 is a metastasis inhibition factor and plays a suppressive role in metastasis in many types of cancer. In this study, a stable NIH/3T3 cell line harboring an inducible Ha-ras(val12) oncogene (designated as 7-4) and small interfering RNAs (siRNAs) were used to clarify the inverse correlation between nm23 and Ha-ras expression both in vitro and in vivo. A derivative 7-4/Z-3 cell line harboring a β-galactosidase reporter gene was used to trace cell metastasis in a murine tumor model. The data presented here reveal that Ha-ras(val12) is able to cause cell morphological changes, induce tumor formation, and promote metastasis of tumor cells to the lungs. In mice with metastases, the immune surveillance against tumor formation was suppressed by Ha-ras(val12) overexpression through an increase in T-reg cells and a decrease of cytotoxic T lymphocytes and natural killer cell populations. Our results suggest that the Ha-ras oncogene regulates morphogenesis, tumorigenesis, and metastasis through suppressing nm23 expression and modulation of immune cell function.

    Anticancer research 2010;30;9;3585-92

  • Ablation of Dicer from murine Schwann cells increases their proliferation while blocking myelination.

    Bremer J, O'Connor T, Tiberi C, Rehrauer H, Weis J and Aguzzi A

    Institute of Neuropathology, University Hospital of Zurich, Zurich, Switzerland.

    The myelin sheaths that surround the thick axons of the peripheral nervous system are produced by the highly specialized Schwann cells. Differentiation of Schwann cells and myelination occur in discrete steps. Each of these requires coordinated expression of specific proteins in a precise sequence, yet the regulatory mechanisms controlling protein expression during these events are incompletely understood. Here we report that Schwann cell-specific ablation of the enzyme Dicer1, which is required for the production of small non-coding regulatory microRNAs, fully arrests Schwann cell differentiation, resulting in early postnatal lethality. Dicer(-/-) Schwann cells had lost their ability to myelinate, yet were still capable of sorting axons. Both cell death and, paradoxically, proliferation of immature Schwann cells was markedly enhanced, suggesting that their terminal differentiation is triggered by growth-arresting regulatory microRNAs. Using microRNA microarrays, we identified 16 microRNAs that are upregulated upon myelination and whose expression is controlled by Dicer in Schwann cells. This set of microRNAs appears to drive Schwann cell differentiation and myelination of peripheral nerves, thereby fulfilling a crucial function for survival of the organism.

    PloS one 2010;5;8;e12450

  • Cooperativity of Cdk4R24C and Ras in melanoma development.

    Chawla R, Procknow JA, Tantravahi RV, Khurana JS, Litvin J and Reddy EP

    Temple University School of Medicine, Fels Institute of Cancer Research and Molecular Biology, Philadelphia, Pennsylvania, USA.

    The importance of the CDK4 protein in human cancer first became evident following the identification of a germ line mutation in the Cdk4 locus that predisposes humans to melanoma. This mutation results in substitution of arginine with cysteine at position 24 (R24C). In an earlier study, we introduced the R24C mutation into the Cdk4 locus of mice using Cre-loxP-mediated "knock-in" technology and observed a very low incidence of spontaneous melanomas in Cdk4(R24C/R24C) mice. This suggested that additional oncogenic mutations might be required for development of melanomas. Here we report an increased incidence of spontaneous cutaneous melanoma in mice expressing the oncogene HRAS(G12V) in melanocytes on a Cdk4(R24C) background. Treatment of Tyr-HRas:Cdk4(R24C/R24C) mice with the carcinogen, DMBA/TPA resulted in a further increase in the number of nevi and melanomas developed when compared with Tyr-HRas:Cdk4(+/+) mice. In summary, in Tyr-HRas:Cdk4(R24C/R24C) mice, we observed that activated CDK4 cooperates with the oncogenic HRAS(G12V) protein to increase the susceptibility of melanoma development in vivo.

    Funded by: NCI NIH HHS: P01 CA95569; NIA NIH HHS: R01 AG22022

    Cell cycle (Georgetown, Tex.) 2010;9;16;3305-14

  • Neuronal Ras activation inhibits adult hippocampal progenitor cell division and impairs spatial short-term memory.

    Manns M, Bichler Z, Leske O and Heumann R

    Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-University-Bochum, Bochum, FRG. Martina.Manns@rub.de

    A large number of endogenous and exogenous factors have been identified to upregulate and downregulate proliferation, differentiation and/or survival of newborn cells in the adult hippocampus. For studying neuronal mechanisms mediating the impact of those factors, we used a transgenic synRas mouse model expressing constitutively activated Valin12-Harvey Ras selectively in differentiated neurons. BrdU injections showed significantly reduced proliferation of new cells within the adult hippocampus of transgenic animals compared with their wild-type siblings. In contrast, the relative survival of newborn cells was increased in synRas mice, although this effect did not fully compensate for diminished proliferation. Inhibition of progenitor cell proliferation and enhancement of cellular survival were more pronounced in males compared with females. Double labelling and doublecortin immunostaining verified that specifically newborn neurons were decreased in synRas mice. Reduced cell generation was observed already 2 h after BrdU pulse injections, identifying an early precursor cell population as target of the inhibitory transgene effect. Differences in proliferation remained stable after 24 h and were specific for the subgranular zone of the dentate gyrus, as subventricular cell generation was not affected supporting a non-cell autonomous effect on neural hippocampal progenitors. Transgene expression only starts with synaptic differentiation and therefore reduced proliferation must represent an indirect secondary consequence of synRas activity in differentiated neurons. This was associated with impaired spatial short-term memory capacities as observed in a radial maze paradigm. Our data suggest that constantly high Ras activity in differentiated neurons downregulates hippocampal precursor cell generation in the neuronal lineage, but is modulated by sex-dependent factors.

    Genes, brain, and behavior 2010;9;5;525-36

  • Ras signalling regulates differentiation and UCP1 expression in models of brown adipogenesis.

    Murholm M, Dixen K and Hansen JB

    Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen N, Denmark.

    Background: The Ras/Raf/MEK/ERK pathway has been recognised as an important signalling module in adipogenesis and adipocyte function, but whether it promotes or inhibits the formation of fat cells has not been reconciled.

    Methods: Here we investigate the significance of Ras signalling intensity on two unrelated models of mouse brown adipocyte differentiation.

    Results: A constitutively active H-Ras mutant (Ras V12) caused a complete block of adipose conversion, as manifested by a lack of both lipid accumulation and induction of adipocyte gene expression. The Ras V12-mediated impediment of differentiation was inefficiently rescued by forced expression of the adipogenic transcription factors C/EBPalpha and PPARgamma. However, the defective differentiation was alleviated by MEK inhibitors, suggesting that the obstruction of differentiation was dependent on activation of ERK. A dominant interfering H-Ras mutant (Ras N17) did not inhibit differentiation, but led to increased expression of genes important for energy dissipation in brown fat cells, including UCP1.

    These data suggest that the intensity of Ras signalling is important for differentiation and UCP1 expression in models of brown adipogenesis.

    Biochimica et biophysica acta 2010;1800;6;619-27

  • Requirement of the NF-kappaB subunit p65/RelA for K-Ras-induced lung tumorigenesis.

    Bassères DS, Ebbs A, Levantini E and Baldwin AS

    Lineberger Comprehensive Cancer Center and Department of Biology, University of North Carolina, Chapel Hill, North Carolina, USA.

    K-Ras-induced lung cancer is a very common disease, for which there are currently no effective therapies. Because therapy directly targeting the activity of oncogenic Ras has been unsuccessful, a different approach for novel therapy design is to identify critical Ras downstream oncogenic targets. Given that oncogenic Ras proteins activate the transcription factor NF-kappaB, and the importance of NF-kappaB in oncogenesis, we hypothesized that NF-kappaB would be an important K-Ras target in lung cancer. To address this hypothesis, we generated a NF-kappaB-EGFP reporter mouse model of K-Ras-induced lung cancer and determined that K-Ras activates NF-kappaB in lung tumors in situ. Furthermore, a mouse model was generated where activation of oncogenic K-Ras in lung cells was coupled with inactivation of the NF-kappaB subunit p65/RelA. In this model, deletion of p65/RelA reduces the number of K-Ras-induced lung tumors both in the presence and in the absence of the tumor suppressor p53. Lung tumors with loss of p65/RelA have higher numbers of apoptotic cells, reduced spread, and lower grade. Using lung cell lines expressing oncogenic K-Ras, we show that NF-kappaB is activated in these cells in a K-Ras-dependent manner and that NF-kappaB activation by K-Ras requires inhibitor of kappaB kinase beta (IKKbeta) kinase activity. Taken together, these results show the importance of the NF-kappaB subunit p65/RelA in K-Ras-induced lung transformation and identify IKKbeta as a potential therapeutic target for K-Ras-induced lung cancer.

    Funded by: NCI NIH HHS: CA73756, CA75080, R01 CA073756; NIAID NIH HHS: R37 AI035098, R37 AI035098-17

    Cancer research 2010;70;9;3537-46

  • The c-Jun NH2-terminal kinase 2 plays a dominant role in human epidermal neoplasia.

    Ke H, Harris R, Coloff JL, Jin JY, Leshin B, Miliani de Marval P, Tao S, Rathmell JC, Hall RP and Zhang JY

    Department of Dermatology and Pharmacology, Duke University, Durham, North Carolina, USA.

    The c-Jun NH(2)-terminal kinase (JNK) signaling cascade has been implicated in a wide range of diseases, including cancer. It is unclear how different JNK proteins contribute to human cancer. Here, we report that JNK2 is activated in more than 70% of human squamous cell carcinoma (SCC) samples and that inhibition of JNK2 pharmacologically or genetically impairs tumorigenesis of human SCC cells. Most importantly, JNK2, but not JNK1, is sufficient to couple with oncogenic Ras to transform primary human epidermal cells into malignancy with features of SCC. JNK2 prevents Ras-induced cell senescence and growth arrest by reducing the expression levels of the cell cycle inhibitor p16 and the activation of NF-kappaB. On the other hand, JNK, along with phosphoinositide 3-kinase, is essential for Ras-induced glycolysis, an energy-producing process known to benefit cancer growth. These data indicate that JNK2 collaborates with other oncogenes, such as Ras, at multiple molecular levels to promote tumorigenesis and hence represents a promising therapeutic target for cancer.

    Funded by: NCI NIH HHS: R01 CA123350-04, R01 CA123350-05, R01CA123350; NIAMS NIH HHS: K01 AR051470-03, K01 AR051470-04, K01 AR051470-05, K01AR051470

    Cancer research 2010;70;8;3080-8

  • Activation of Rho GTPases in Smith-Lemli-Opitz syndrome: pathophysiological and clinical implications.

    Jiang XS, Wassif CA, Backlund PS, Song L, Holtzclaw LA, Li Z, Yergey AL and Porter FD

    Section on Molecular Dysmorphology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health, National Institutes of Health, Bethesda, MD 20892, USA.

    Smith-Lemli-Opitz syndrome (SLOS) is a malformation syndrome with neurocognitive deficits due to mutations of DHCR7 that impair the reduction of 7-dehydrocholesterol to cholesterol. To investigate the pathological processes underlying the neurocognitive deficits, we compared protein expression in Dhcr7(+/+) and Dhcr7(Delta3-5/Delta3-5) brain tissue. One of the proteins identified was cofilin-1, an actin depolymerizing factor which regulates neuronal dendrite and axon formation. Differential expression of cofilin-1 was due to increased phosphorylation. Phosphorylation of cofilin-1 is regulated by Rho GTPases through Rho-Rock-Limk-Cofilin-1 and Rac/Cdc42-Pak-Limk-Cofilin-1 pathways. Pull-down assays were used to demonstrate increased activation of RhoA, Rac1 and Cdc42 in Dhcr7(Delta3-5/Delta3-5) brains. Consistent with increased activation of these Rho GTPases, we observed increased phosphorylation of both Limk and Pak in mutant brain tissue. Altered Rho/Rac signaling impairs normal dendritic and axonal formation, and mutations in genes encoding regulators and effectors of the Rho GTPases underlie other human mental retardation syndromes. Thus, we hypothesized that aberrant activation of Rho/Rac could have functional consequences for dendrite and axonal growth. In vitro analysis of Dhcr7(Delta3-5/Delta3-5) hippocampal neurons demonstrated both axonal and dendritic abnormalities. Developmental abnormalities of neuronal process formation may contribute to the neurocognitive deficits found in SLOS and may represent a potential target for therapeutic intervention.

    Funded by: Intramural NIH HHS

    Human molecular genetics 2010;19;7;1347-57

  • Genetic analysis of Ras signalling pathways in cell proliferation, migration and survival.

    Drosten M, Dhawahir A, Sum EY, Urosevic J, Lechuga CG, Esteban LM, Castellano E, Guerra C, Santos E and Barbacid M

    Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas, Melchor Fernández Almagro 3, Madrid, Spain.

    We have used mouse embryonic fibroblasts (MEFs) devoid of Ras proteins to illustrate that they are essential for proliferation and migration, but not for survival, at least in these cells. These properties are unique to the Ras subfamily of proteins because ectopic expression of other Ras-like small GTPases, even when constitutively active, could not compensate for the absence of Ras proteins. Only constitutive activation of components of the Raf/Mek/Erk pathway was sufficient to sustain normal proliferation and migration of MEFs devoid of Ras proteins. Activation of the phosphatidylinositol 3-kinase (PI3K)/PTEN/Akt and Ral guanine exchange factor (RalGEF)/Ral pathways, either alone or in combination, failed to induce proliferation or migration of Rasless cells, although they cooperated with Raf/Mek/Erk signalling to reproduce the full response mediated by Ras signalling. In contrast to current hypotheses, Ras signalling did not induce proliferation by inducing expression of D-type Cyclins. Rasless MEFs had normal levels of Cyclin D1/Cdk4 and Cyclin E/Cdk2. However, these complexes were inactive. Inactivation of the pocket proteins or knock down of pRb relieved MEFs from their dependence on Ras signalling to proliferate.

    The EMBO journal 2010;29;6;1091-104

  • H-, N- and Kras cooperatively regulate lymphatic vessel growth by modulating VEGFR3 expression in lymphatic endothelial cells in mice.

    Ichise T, Yoshida N and Ichise H

    Laboratory of Developmental Genetics, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.

    Mammalian Ras, which is encoded by three independent genes, has been thought to be a versatile component of intracellular signalling. However, when, where and how Ras signalling plays essential roles in development and whether the three Ras genes have overlapping functions in particular cells remain unclear. Here, we show that the three Ras proteins dose-dependently regulate lymphatic vessel growth in mice. We find that lymphatic vessel hypoplasia is a common phenotype in Ras compound knockout mice and that overexpressed normal Ras in an endothelial cell lineage selectively causes lymphatic vessel hyperplasia in vivo. Overexpression of normal Ras in lymphatic endothelial cells leads to sustained MAPK activation, cellular viability and enhanced endothelial network formation under serum-depleted culture conditions in vitro, and knockdown of endogenous Ras in lymphatic endothelial cells impairs cell proliferation, MAPK activation, cell migration and endothelial network formation. Ras overexpression and knockdown result in up- and downregulation of vascular endothelial growth factor receptor (VEGFR) 3 expression, respectively, in lymphatic endothelial cells in vitro. The close link between Ras and VEGFR3 in vitro is consistent with the result that Ras knockout and transgenic alleles are genetic modifiers in lymphatic vessel hypoplasia caused by Vegfr3 haploinsufficiency. Our findings demonstrate a cooperative function of the three Ras proteins in normal development, and also provide a novel aspect of VEGFR3 signalling modulated by Ras in lymphangiogenesis.

    Development (Cambridge, England) 2010;137;6;1003-13

  • Activated Ras alters lens and corneal development through induction of distinct downstream targets.

    Burgess D, Zhang Y, Siefker E, Vaca R, Kuracha MR, Reneker L, Overbeek PA and Govindarajan V

    Department of Surgery, 2500 California Plaza, Creighton University, Omaha, NE 68178, USA.

    Background: Mammalian Ras genes regulate diverse cellular processes including proliferation and differentiation and are frequently mutated in human cancers. Tumor development in response to Ras activation varies between different tissues and the molecular basis for these variations are poorly understood. The murine lens and cornea have a common embryonic origin and arise from adjacent regions of the surface ectoderm. Activation of the fibroblast growth factor (FGF) signaling pathway induces the corneal epithelial cells to proliferate and the lens epithelial cells to exit the cell cycle. The molecular mechanisms that regulate the differential responses of these two related tissues have not been defined. We have generated transgenic mice that express a constitutively active version of human H-Ras in their lenses and corneas.

    Results: Ras transgenic lenses and corneal epithelial cells showed increased proliferation with concomitant increases in cyclin D1 and D2 expression. This initial increase in proliferation is sustained in the cornea but not in the lens epithelial cells. Coincidentally, cdk inhibitors p27Kip1 and p57Kip2 were upregulated in the Ras transgenic lenses but not in the corneas. Phospho-Erk1 and Erk2 levels were elevated in the lens but not in the cornea and Spry 1 and Spry 2, negative regulators of Ras-Raf-Erk signaling, were upregulated more in the corneal than in the lens epithelial cells. Both lens and corneal differentiation programs were sensitive to Ras activation. Ras transgenic embryos showed a distinctive alteration in the architecture of the lens pit. Ras activation, though sufficient for upregulation of Prox1, a transcription factor critical for cell cycle exit and initiation of fiber differentiation, is not sufficient for induction of terminal fiber differentiation. Expression of Keratin 12, a marker of corneal epithelial differentiation, was reduced in the Ras transgenic corneas.

    Conclusions: Collectively, these results suggest that Ras activation a) induces distinct sets of downstream targets in the lens and cornea resulting in distinct cellular responses and b) is sufficient for initiation but not completion of lens fiber differentiation.

    Funded by: NCRR NIH HHS: G20 RR 024001; NEI NIH HHS: EY017610, R01 EY017610

    BMC developmental biology 2010;10;13

  • Analysis of k-ras nuclear expression in fibroblasts and mesangial cells.

    Fuentes-Calvo I, Blázquez-Medela AM, Santos E, López-Novoa JM and Martínez-Salgado C

    Unidad de Fisiopatología Renal y Cardiovascular, Instituto Reina Sofía de Investigación Nefrológica, Universidad de Salamanca, Salamanca, Spain.

    Background: Ras GTPases are considered cytoplasmic proteins that must be localized to cell membranes for activation, and there are few evidences of the presence of any Ras isoform in nuclei of eukaryotic cells.

    Using conventional antibodies and inmunocytochemistry, differential centrifugation and western blot, we have observed the putative presence of K-Ras isoform in the nuclei of fibroblasts and mesangial cells. In order to avoid cross-reactions with other Ras isoforms, and using antibodies against K-Ras (R-3400, H3845-M01, sc-30) or pan-Ras (05-516, OP40) in cells that only expressed the K-Ras isoform (fibroblasts obtained from H-ras(-/-),N-ras(-/-) mice) we also detected some nuclear positive expression. To further probe the identity of nuclear K-Ras, we have generated K-Ras knockout (K-ras(-/-)) embrionary fibroblasts by mating of K-ras(+/-) heterozygote mice. Using specific antibodies, only H- and N-Ras isoforms were observed in the cytoplasm of K-ras(-/-) fibroblasts. However, both K-Ras4A and K-Ras4B positive signals were detected by immunocytochemistry and Western blot with two commercial antibodies (sc-522 and sc-521 against each isoforms, respectively) in both cytoplasm and nuclei from K-ras(-/-) fibroblasts.

    We show that the presence of K-Ras4B in fibroblast nuclei, already described by other authors, is probably due to a cross-reaction of the antibody with an undetermined nucleolar protein. Although this study also shows the possible nuclear expression of K-Ras isoform in fibroblasts or in mesangial cells, it also reveals the importance of being cautious in these studies about distribution of protein isoforms due to some important limitations imposed by the unspecificity of the antibodies or contaminations in cellular preparations.

    PloS one 2010;5;1;e8703

  • Modeling the effect of the RB tumor suppressor on disease progression: dependence on oncogene network and cellular context.

    Dean JL, McClendon AK, Stengel KR and Knudsen ES

    Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.

    The retinoblastoma tumor suppressor, RB, is a key regulator of cellular proliferation that is functionally inactivated at high frequency in human cancer. Although RB has been extensively studied with regard to tumor etiology, loss of tumor-suppressor function often occurs relatively late in tumor progression. Therefore, inactivation of RB could have a profound impact on the behavior of tumors driven by discrete oncogenes. Here, collaboration between Ras or c-Myc deregulation and RB functional state was investigated in a model of conditional genetic deletion to decipher the effects related to disease progression. These studies showed that RB loss had a robust impact on mitogen dependence, anchorage dependence and overall survival, which was significantly modified by oncogene activation. Specifically, RB deficiency predisposed c-Myc-expressing cells to cell death and reduced overall tumorigenic proliferation. In contrast, RB deficiency exacerbated the tumorigenic behavior of Ras-transformed cells in both the model system and human tumor cell lines. As these tumors exhibited highly aggressive behavior, the possibility of exploiting the intrinsic sensitivity to cell death with RB loss was evaluated. Particularly, although Ras-transformed, RB-deficient cells bypassed the G1-checkpoint elicited by pharmacological activation of the p53 pathway, they were also highly sensitized to cell death. Altogether, these data suggest that the impact of RB deletion is dependent on the oncogene milieu, and can directly contribute to transformed phenotypes and response to therapeutic intervention.

    Oncogene 2010;29;1;68-80

  • Angiotensin II-induced activation of c-Ret signaling is critical in ureteric bud branching morphogenesis.

    Song R, Spera M, Garrett C and Yosypiv IV

    Department of Pediatrics, Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center, New Orleans, LA 70112, USA.

    The renin-angiotensin system (RAS) plays a critical role in ureteric bud (UB) and kidney morphogenesis. Mutations in the genes encoding components of the RAS cause a spectrum of congenital abnormalities of the kidney and urinary tract (CAKUT). However, the mechanisms by which aberrations in the RAS result in CAKUT are poorly understood. Given that c-Ret receptor tyrosine kinase (RTK) is a major inducer of UB branching, the present study tested the hypothesis that angiotensin (Ang) II-induced activation of c-Ret plays a critical role in UB branching morphogenesis. E12.5 mice metanephroi were grown for 24h in the presence or absence of Ang II, Ang II AT(1) receptor (AT(1)R) antagonist candesartan, phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 or ERK1/2 inhibitor PD98059. Ang II increased the number of UB tips (61+/-2.4 vs. 45+/-4.3, p<0.05) compared with control. Quantitative RT-PCR analysis demonstrated that Ang II increased c-Ret mRNA levels in the kidney (1.35+/-0.05 vs. 1.0+/-0, p<0.01) and in the UB cells (1.28+/-0.04 vs. 1.0+/-0, p<0.01) compared to control. This was accompanied by increased Tyr(1062)Ret phosphorylation by Ang II (5.5+/-0.9 vs. 1.8+/-0.4 relative units, p<0.05). In addition, treatment of UB cells with Ang II (10(-5)M) increased phosphorylation of Akt compared to control (213+/-16 vs. 100+/-20%, p<0.05). In contrast, treatment of metanephroi or UB cells with candesartan decreased c-Ret mRNA levels (0.72+/-0.06 vs. 1.0+/-0, p<0.01; 0.68+/-0.07 vs. 1.0+/-0, p<0.05, respectively) compared with control. Ang II-induced UB branching was abrogated by LY294002 (24+/-2.6 vs. 37+/-3.0, p<0.05) or PD98059 (33+/-2.0 vs. 48+/-2.2, p<0.01). These data demonstrate that Ang II-induced UB branching depends on activation of Akt and ERK1/2. We conclude that cross-talk between the RAS and c-Ret signaling plays an important role in the development of the renal collecting system.

    Funded by: NCRR NIH HHS: P20 RR17659; NIDDK NIH HHS: DK-071699, R01 DK071699-01A1, R01 DK071699-04

    Mechanisms of development 2010;127;1-2;21-7

  • Reduced cell death, invasive and angiogenic features conferred by BRCA1-deficiency in mammary epithelial cells transformed with H-Ras.

    Navaraj A, Finnberg N, Dicker DT, Yang W, Matthew EM and El-Deiry WS

    Laboratory of Molecular Oncology and Cell Cycle Regulation, Department of Medicine (Hematology/Oncology), University of Pennsylvania School of Medicine, Philadelphia, PA, USA.

    To investigate the role of tumor suppressors BRCA1 and p53 proteins in human breast tumorigenesis, we transformed immortalized human mammary epithelial cells, MCF10A, with or without BRCA1/p53 gene-specific knockdowns. Stable knockdown of BRCA1 alone in MCF10A cells led to centrosome amplification, impaired p53 protein stability, increased sensitivity towards DNA-damaging agents, defective chromosomal condensation at mitosis and elevated protein levels of cyclin D1 and c-myc. While over-expression of mutant H-Ras transformed MCF10A cells, depletion of BRCA1 dramatically enhanced the in vivo tumorigenesis that was associated with higher levels of VEGF, enhanced vascularization and less apoptosis in the BRCA1-deficient Ras-transformed tumors. The Ras-transformed BRCA1-deficient tumors exhibited features of the epithelial-to-mesenchymal transition, appeared to secrete matrix metalloproteases as visualized by in vivo bio-imaging of tumors using fluorescent probe MMP680, and were locally metastatic to lymph nodes. Our results suggest that loss of BRCA1 function may contribute to the aggressiveness of Ras-MAPK driven human breast cancer with associated increase in levels of cyclin D1 and c-myc, enhanced MAPK activity, angiogenic potential & invasiveness. This mammary xenograft tumor model may be useful as a tool to understand human breast tumor angiogenesis and metastasis, as well as to test candidate therapeutics.

    Funded by: NCI NIH HHS: CA105008, CA123258, CA94975, R01 CA123258-01, R01 CA123258-02, R01 CA123258-03, R01 CA123258-04, R01 CA123258-05, R01 CA135273, R01 CA135273-04

    Cancer biology & therapy 2009;8;24;2417-44

  • H-ras expression in immortalized keratinocytes produces an invasive epithelium in cultured skin equivalents.

    Vaughan MB, Ramirez RD, Andrews CM, Wright WE and Shay JW

    Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America. mvaughan4@uco.edu

    Background: Ras proteins affect both proliferation and expression of collagen-degrading enzymes, two important processes in cancer progression. Normal skin architecture is dependent both on the coordinated proliferation and stratification of keratinocytes, as well as the maintenance of a collagen-rich basement membrane. In the present studies we sought to determine whether expression of H-ras in skin keratinocytes would affect these parameters during the establishment and maintenance of an in vitro skin equivalent.

    Previously described cdk4 and hTERT immortalized foreskin keratinocytes were engineered to express ectopically introduced H-ras. Skin equivalents, composed of normal fibroblast-contracted collagen gels overlaid with keratinocytes (immortal or immortal expressing H-ras), were prepared and incubated for 3 weeks. Harvested tissues were processed and sectioned for histology and antibody staining. Antigens specific to differentiation (involucrin, keratin-14, p63), basement-membrane formation (collagen IV, laminin-5), and epithelial to mesenchymal transition (EMT; e-cadherin, vimentin) were studied. Results showed that H-ras keratinocytes produced an invasive, disorganized epithelium most apparent in the lower strata while immortalized keratinocytes fully stratified without invasive properties. The superficial strata retained morphologically normal characteristics. Vimentin and p63 co-localization increased with H-ras overexpression, similar to basal wound-healing keratinocytes. In contrast, the cdk4 and hTERT immortalized keratinocytes differentiated similarly to normal unimmortalized keratinocytes.

    The use of isogenic derivatives of stable immortalized keratinocytes with specified genetic alterations may be helpful in developing more robust in vitro models of cancer progression.

    Funded by: NCRR NIH HHS: P20 RR016478; PHS HHS: P2PRR016478

    PloS one 2009;4;11;e7908

  • Localized diacylglycerol-dependent stimulation of Ras and Rap1 during phagocytosis.

    Botelho RJ, Harrison RE, Stone JC, Hancock JF, Philips MR, Jongstra-Bilen J, Mason D, Plumb J, Gold MR and Grinstein S

    Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada.

    We describe a role for diacylglycerol in the activation of Ras and Rap1 at the phagosomal membrane. During phagocytosis, Ras density was similar on the surface and invaginating areas of the membrane, but activation was detectable only in the latter and in sealed phagosomes. Ras activation was associated with the recruitment of RasGRP3, a diacylglycerol-dependent Ras/Rap1 exchange factor. Recruitment to phagosomes of RasGRP3, which contains a C1 domain, parallels and appears to be due to the formation of diacylglycerol. Accordingly, Ras and Rap1 activation was precluded by antagonists of phospholipase C and of diacylglycerol binding. Ras is dispensable for phagocytosis but controls activation of extracellular signal-regulated kinase, which is partially impeded by diacylglycerol inhibitors. By contrast, cross-activation of complement receptors by stimulation of Fcgamma receptors requires Rap1 and involves diacylglycerol. We suggest a role for diacylglycerol-dependent exchange factors in the activation of Ras and Rap1, which govern distinct processes induced by Fcgamma receptor-mediated phagocytosis to enhance the innate immune response.

    Funded by: NCI NIH HHS: CA116034, R01 CA116034; NIGMS NIH HHS: GM55279, R01 GM055279, R01 GM066717

    The Journal of biological chemistry 2009;284;42;28522-32

  • FAK phosphorylation by ERK primes ras-induced tyrosine dephosphorylation of FAK mediated by PIN1 and PTP-PEST.

    Zheng Y, Xia Y, Hawke D, Halle M, Tremblay ML, Gao X, Zhou XZ, Aldape K, Cobb MH, Xie K, He J and Lu Z

    Brain Tumor Center and Department of Neuro-Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.

    Activated Ras has been found in many types of cancer. However, the mechanism underlying Ras-promoted tumor metastasis remains unclear. We demonstrate here that activated Ras induces tyrosine dephosphorylation and inhibition of FAK mediated by the Ras downstream Fgd1-Cdc42-PAK1-MEK-ERK signaling cascade. ERK phosphorylates FAK S910 and recruits PIN1 and PTP-PEST, which colocalize with FAK at the lamellipodia of migrating cells. PIN1 binding and prolyl isomerization of FAK cause PTP-PEST to interact with and dephosphorylate FAK Y397. Inhibition of FAK mediated by this signal relay promotes Ras-induced cell migration, invasion, and metastasis. These findings uncover the importance of sequential modification of FAK-by serine phosphorylation, isomerization, and tyrosine dephosphorylation--in the regulation of FAK activity and, thereby, in Ras-related tumor metastasis.

    Funded by: NCI NIH HHS: 5R01CA109035, R01 CA109035, R01 CA109035-05; NIDDK NIH HHS: R37 DK034128

    Molecular cell 2009;35;1;11-25

  • The level of the transcription factor Pax6 is essential for controlling the balance between neural stem cell self-renewal and neurogenesis.

    Sansom SN, Griffiths DS, Faedo A, Kleinjan DJ, Ruan Y, Smith J, van Heyningen V, Rubenstein JL and Livesey FJ

    Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK.

    Neural stem cell self-renewal, neurogenesis, and cell fate determination are processes that control the generation of specific classes of neurons at the correct place and time. The transcription factor Pax6 is essential for neural stem cell proliferation, multipotency, and neurogenesis in many regions of the central nervous system, including the cerebral cortex. We used Pax6 as an entry point to define the cellular networks controlling neural stem cell self-renewal and neurogenesis in stem cells of the developing mouse cerebral cortex. We identified the genomic binding locations of Pax6 in neocortical stem cells during normal development and ascertained the functional significance of genes that we found to be regulated by Pax6, finding that Pax6 positively and directly regulates cohorts of genes that promote neural stem cell self-renewal, basal progenitor cell genesis, and neurogenesis. Notably, we defined a core network regulating neocortical stem cell decision-making in which Pax6 interacts with three other regulators of neurogenesis, Neurog2, Ascl1, and Hes1. Analyses of the biological function of Pax6 in neural stem cells through phenotypic analyses of Pax6 gain- and loss-of-function mutant cortices demonstrated that the Pax6-regulated networks operating in neural stem cells are highly dosage sensitive. Increasing Pax6 levels drives the system towards neurogenesis and basal progenitor cell genesis by increasing expression of a cohort of basal progenitor cell determinants, including the key transcription factor Eomes/Tbr2, and thus towards neurogenesis at the expense of self-renewal. Removing Pax6 reduces cortical stem cell self-renewal by decreasing expression of key cell cycle regulators, resulting in excess early neurogenesis. We find that the relative levels of Pax6, Hes1, and Neurog2 are key determinants of a dynamic network that controls whether neural stem cells self-renew, generate cortical neurons, or generate basal progenitor cells, a mechanism that has marked parallels with the transcriptional control of embryonic stem cell self-renewal.

    Funded by: Cancer Research UK; Medical Research Council: MC_U127527199; NINDS NIH HHS: R01 NS034661, R01 NS099099; Wellcome Trust

    PLoS genetics 2009;5;6;e1000511

  • Constitutively enhanced p21Ras activity amplifies dendritic remodeling of hippocampal neurons during physical activity.

    Alpár A, Naumann N, Arendt T and Gärtner U

    Department of Anatomy, Histology and Embryology, Semmelweis University Medical School, Tuzoltó u. 58, H-1450 Budapest, Hungary. dralpar@gmx.net

    In the present study we show that overexpression of constitutively active Ras amplifies the dendritic remodeling observed when animals were allowed to be physically active. The monomeric G-protein Ras is a key molecular trigger of distinct signal transduction pathways that play an important role in proper functioning of neurons. Our previous studies on Ras-transgenic synRas mice have demonstrated a considerable impact of Ras on dendritic growth, extension and synaptic connectivity of neurons. Voluntary access to a running wheel resulted in enlargement of hippocampal pyramidal cell dendrites in wild-type mice as expected. However, constitutively elevated Ras activity further enhanced dendritic growth and branching especially of apical arbors. The resultant dendritic surface gain was paralleled by a significant increase in dendritic spine density. Since Ras is crucially involved in signaling and cascades of neurotrophins that are elevated after physical activity, these results strongly suggest an important role of Ras in dendritic dynamics during induced neuronal remodeling.

    International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience 2009;27;4;407-11

  • Endogenous expression of Hras(G12V) induces developmental defects and neoplasms with copy number imbalances of the oncogene.

    Chen X, Mitsutake N, LaPerle K, Akeno N, Zanzonico P, Longo VA, Mitsutake S, Kimura ET, Geiger H, Santos E, Wendel HG, Franco A, Knauf JA and Fagin JA

    Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.

    We developed mice with germline endogenous expression of oncogenic Hras to study effects on development and mechanisms of tumor initiation. They had high perinatal mortality, abnormal cranial dimensions, defective dental ameloblasts, and nasal septal deviation, consistent with some of the features of human Costello syndrome. These mice developed papillomas and angiosarcomas, which were associated with Hras(G12V) allelic imbalance and augmented Hras signaling. Endogenous expression of Hras(G12V) was also associated with a higher mutation rate in vivo. Tumor initiation by Hras(G12V) likely requires augmentation of signal output, which in papillomas and angiosarcomas is achieved via increased Hras-gene copy number, which may be favored by a higher mutation frequency in cells expressing the oncoprotein.

    Funded by: NCI NIH HHS: CA50706, CA72597, P30 CA08748, R24 CA83084; NIDDK NIH HHS: T32 DK07313

    Proceedings of the National Academy of Sciences of the United States of America 2009;106;19;7979-84

  • BLNK binds active H-Ras to promote B cell receptor-mediated capping and ERK activation.

    Imamura Y, Oda A, Katahira T, Bundo K, Pike KA, Ratcliffe MJ and Kitamura D

    Division of Molecular Biology, Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda, Chiba 278-0022, Japan.

    Cross-linked B cell receptor (BCR) aggregates on the cell surface, then assembles into the "cap" where Ras is co-localized, and transduces various intracellular signals including Ras-ERK activation. BCR signals induce proliferation, differentiation, or apoptosis of B cells depending on their maturational stage. The adaptor protein BLNK binds various signaling proteins and Igalpha, a signaling subunit of the BCR complex, and plays an important role in the BCR signal transduction. BLNK was shown to be required for activation of ERK, but not of Ras, after BCR cross-linking, raising a question how BLNK facilitates ERK activation. Here we demonstrate that BLNK binds the active form of H-Ras, and their binding is facilitated by BCR cross-linking. We have identified a 10-amino acid Ras-binding domain within BLNK that is necessary for restoration of BCR-mediated ERK activation in BLNK-deficient B cells and for anti-apoptotic signaling. The Ras-binding domain fused with a CD8alpha-Igalpha chimeric receptor could induce prolonged ERK phosphorylation, transcriptional activation of Elk1, as well as the capping of the receptor in BLNK-deficient B cells. These results indicate that BLNK recruits active H-Ras to the BCR complex, which is essential for sustained surface expression of BCR in the form of the cap and for the signal leading to functional ERK activation.

    The Journal of biological chemistry 2009;284;15;9804-13

  • Oncogenic H-Ras and PI3K signaling can inhibit E-cadherin-dependent apoptosis and promote cell survival after photodynamic therapy in mouse keratinocytes.

    Espada J, Galaz S, Sanz-Rodríguez F, Blázquez-Castro A, Stockert JC, Bagazgoitia L, Jaén P, González S, Cano A and Juarranz A

    Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain. jespada@iib.uam.es

    Maintenance of E-cadherin mediated cell-cell contacts is often required for the survival of epithelial cells and tissues. Here we report that oncogenic activation of H-Ras in murine keratinocytes can prevent cell death induced by immunological disruption of E-cadherin adhesion. A similar situation was observed in cells showing constitutive activation of the p110 alpha catalytic subunit of class IA PI3K. This protective effect is associated with beta-catenin-dependent transcription and with activation of survival factor Akt/PKB. In addition, we induced cell death by employing photodynamic therapy, using Zn-phthalocyanine as a photosensitizer that targets E-cadherin adhesion complexes. We have found that cell death based on this photodynamic action is also bypassed in cells showing constitutive activation of H-Ras and p110 alpha. Taken together, these results indicate that H-Ras/PI3K/Akt signaling plays a key role in cell survival mediated by E-cadherin cell-cell contacts.

    Journal of cellular physiology 2009;219;1;84-93

  • PKCdelta survival signaling in cells containing an activated p21Ras protein requires PDK1.

    Xia S, Chen Z, Forman LW and Faller DV

    Cancer Research Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA.

    Protein kinase C delta (PKCdelta) modulates cell survival and apoptosis in diverse cellular systems. We recently reported that PKCdelta functions as a critical anti-apoptotic signal transducer in cells containing activated p21(Ras) and results in the activation of AKT, thereby promoting cell survival. How PKCdelta is regulated by p21(Ras), however, remains incompletely understood. In this study, we show that PKCdelta, as a transducer of anti-apoptotic signals, is activated by phosphotidylinositol 3' kinase/phosphoinositide-dependent kinase 1 (PI(3)K-PDK1) to deliver the survival signal to Akt in the environment of activated p21(Ras). PDK1 is upregulated in cells containing an activated p21Ras. Knock-down of PDK1, PKCdelta, or AKT forces cells containing activated p21(Ras) to undergo apoptosis. PDK1 regulates PKCdelta activity, and constitutive expression of PDK1 increases PKCdelta activity in different cell types. Conversely, expression of a kinase-dead (dominant-negative) PDK1 significantly suppresses PKCdelta activity. p21(Ras)-mediated survival signaling is therefore regulated by via a PI(3)K-AKT pathway, which is dependent upon both PDK1 and PKCdelta, and PDK1 activates and regulates PKCdelta to determine the fate of cells containing a mutated, activated p21(Ras).

    Funded by: NCI NIH HHS: CA108100, CA112102, R01 CA112102, R01 CA112102-01A1, R01 CA112102-02, R01 CA112102-03, R01 CA112102-03S1, R01 CA112102-04, R01 CA112102-04S1, R41 CA108100, R41 CA108100-01

    Cellular signalling 2009;21;4;502-8

  • Ha-ras oncogene-induced Stat3 phosphorylation enhances oncogenicity of the cell.

    Yeh HH, Giri R, Chang TY, Chou CY, Su WC and Liu HS

    Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China.

    The ras oncogene needs a second factor to induce transformation and tumorigenicity of the cell. In this study, we show that mouse fibroblast 7-4-Stat3C cells overexpressing both Ha-ras(val12) oncogene and active-form Stat3 (Stat3C) showed higher colony formation in soft agar and xenograft tumor growth in BALB/c mice. Further studies show that both serine-727 and tyrosine-705 of Stat3 were phosphorylated while Ha-ras was overexpressed. Interleukin-6 (IL-6)-induced phosphorylation of tyrosine-705 and serine-727, as well as DNA-binding and transcriptional activity of Stat3 were further enhanced by Ha-ras overexpression. In addition, overexpression of Stat3C in 7-4-Stat3C cells prevented the cells from morphological change and apoptosis triggered by the Ha-ras oncogene under serum-depleted conditions. We demonstrate that Ha-ras and Stat3 acting together synergistically induce Stat3 phosphorylation at serine-727 phosphorylation and cyclin D1 expression and further enhance transformation and tumorigenicity of the cell. Ha-ras-induced Stat3 phosphorylation at serine-727 plays a pivotal role in transcriptional activation of cyclin D1 and suppression of cell apoptosis. The effect of Ha-ras on Stat3 phosphorylation at serine-727 was also detected in human bladder (T24) and lung (H460) cancer cells. Stat3 phosphorylation at serine-727 is important in Ras-related tumorigenesis.

    DNA and cell biology 2009;28;3;131-9

  • Ras subcellular localization defines extracellular signal-regulated kinase 1 and 2 substrate specificity through distinct utilization of scaffold proteins.

    Casar B, Arozarena I, Sanz-Moreno V, Pinto A, Agudo-Ibáñez L, Marais R, Lewis RE, Berciano MT and Crespo P

    Departamento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria, Consejo Superior de Investigaciones Científicas-IDICAN-Universidad de Cantabria, Santander, 39011 Cantabria, Spain.

    Subcellular localization influences the nature of Ras/extracellular signal-regulated kinase (ERK) signals by unknown mechanisms. Herein, we demonstrate that the microenvironment from which Ras signals emanate determines which substrates will be preferentially phosphorylated by the activated ERK1/2. We show that the phosphorylation of epidermal growth factor receptor (EGFr) and cytosolic phospholipase A(2) (cPLA(2)) is most prominent when ERK1/2 are activated from lipid rafts, whereas RSK1 is mainly activated by Ras signals from the disordered membrane. We present evidence indicating that the underlying mechanism of this substrate selectivity is governed by the participation of different scaffold proteins that distinctively couple ERK1/2, activated at defined microlocalizations, to specific substrates. As such, we show that for cPLA(2) activation, ERK1/2 activated at lipid rafts interact with KSR1, whereas ERK1/2 activated at the endoplasmic reticulum utilize Sef-1. To phosphorylate the EGFr, ERK1/2 activated at lipid rafts require the participation of IQGAP1. Furthermore, we demonstrate that scaffold usage markedly influences the biological outcome of Ras site-specific signals. These results disclose an unprecedented spatial regulation of ERK1/2 substrate specificity, dictated by the microlocalization from which Ras signals originate and by the selection of specific scaffold proteins.

    Molecular and cellular biology 2009;29;5;1338-53

  • Regulation and function of neuronal GTP-Ras in facial motor nerve regeneration.

    Makwana M, Serchov T, Hristova M, Bohatschek M, Gschwendtner A, Kalla R, Liu Z, Heumann R and Raivich G

    Perinatal Brain Repair Group, Department of Obstetrics & Gynaecology, EGA Institute of Women's Health, University College London, London, UK.

    Activation of Ras into the GTP-binding, 'ON' state is a key switch in the neurotrophin-mediated neuronal survival and neurite outgrowth, in vitro as well as in vivo. In the current study we explored changes in GTP-Ras levels following facial nerve injury and the ensuing regeneration and the effects of perturbing these changes in vivo using synapsin-promoter mediated neuronal expression of constitutively active Val12H-Ras (synRas). Quantification of GTP-Ras and total Ras revealed a precipitous drop in the relative GTP-Ras levels in the axotomized facial motor nucleus, to 40% of normal levels at 2 days after cut, followed by a partial recovery to 50-65% at 4-28 days. On western blots, control and axotomized nuclei from synRas mutants showed a 2.2- and 2.5-fold elevation in GTP-Ras, respectively, compared with their wild type littermate controls (p < 5%, anova, TUKEY post-hoc), with the levels in the axotomized synRas nucleus slightly but not significantly above that in the uninjured littermate control (p = 9.9%). Similar increase was also observed in the pERK but not pAKT targets of the Ras cascade. This moderate elevation of GTP-Ras strongly curtailed post-traumatic neuronal cell death (-65%), the influx of T-cells (-48%) as well as other parameters of neuroinflammatory response. Although synRas did not affect the speed of axonal regeneration or functional recovery it caused a very pronounced increase in central axonal sprouting. These current data emphasize the role of reduced active Ras, and by extension, the reduced overall level of retrograde neurotrophin signalling after axotomy, in mediating post-traumatic cell death and inflammation and in restricting the sprouting response. Moreover, the neuroprotective and central sprouting-enhancing effects of neuronal Val12H-Ras could help promote recovery in CNS injury.

    Journal of neurochemistry 2009;108;6;1453-63

  • ILEI requires oncogenic Ras for the epithelial to mesenchymal transition of hepatocytes and liver carcinoma progression.

    Lahsnig C, Mikula M, Petz M, Zulehner G, Schneller D, van Zijl F, Huber H, Csiszar A, Beug H and Mikulits W

    Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Borschke-Gasse 8a, Vienna, Austria.

    In human hepatocellular carcinoma (HCC), epithelial to mesenchymal transition (EMT) correlates with aggressiveness of tumors and poor survival. We employed a model of EMT based on immortalized p19(ARF) null hepatocytes (MIM), which display tumor growth upon expression of oncogenic Ras and undergo EMT through the synergism of Ras and transforming growth factor (TGF)-beta. Here, we show that the interleukin-related protein interleukin-like EMT inducer (ILEI), a novel EMT-, tumor- and metastasis-inducing protein, cooperates with oncogenic Ras to cause TGF-beta-independent EMT. Ras-transformed MIM hepatocytes overexpressing ILEI showed cytoplasmic E-cadherin, loss of ZO-1 and induction of alpha-smooth muscle actin as well as platelet-derived growth factor (PDGF)/PDGF-R isoforms. As shown by dominant-negative PDGF-R expression in these cells, ILEI-induced PDGF signaling was required for enhanced cell migration, nuclear accumulation of beta-catenin, nuclear pY-Stat3 and accelerated growth of lung metastases. In MIM hepatocytes expressing the Ras mutant V12-C40, ILEI collaborated with PI3K signaling resulting in tumor formation without EMT. Clinically, human HCC samples showed granular or cytoplasmic localization of ILEI correlating with well and poorly differentiated tumors, respectively. In conclusion, these data indicate that ILEI requires cooperation with oncogenic Ras to govern hepatocellular EMT through mechanisms involving PDGF-R/beta-catenin and PDGF-R/Stat3 signaling.

    Funded by: Austrian Science Fund FWF: F 2801, F 2802, F 2806, P 19598

    Oncogene 2009;28;5;638-50

  • The protein phosphatase 2A regulatory subunits B'beta and B'delta mediate sustained TrkA neurotrophin receptor autophosphorylation and neuronal differentiation.

    Van Kanegan MJ and Strack S

    Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.

    Nerve growth factor (NGF) is critical for the differentiation and maintenance of neurons in the peripheral and central nervous system. Sustained autophosphorylation of the TrkA receptor tyrosine kinase and long-lasting activation of downstream kinase cascades are hallmarks of NGF signaling, yet our knowledge of the molecular mechanisms underlying prolonged TrkA activity is incomplete. Protein phosphatase 2A (PP2A) is a heterotrimeric Ser/Thr phosphatase composed of a scaffolding, catalytic, and regulatory subunit (B, B', and B" gene families). Here, we employ a combination of pharmacological inhibitors, regulatory subunit overexpression, PP2A scaffold subunit exchange, and RNA interference to show that PP2A containing B' family regulatory subunits participates in sustained NGF signaling in PC12 cells. Specifically, two neuron-enriched regulatory subunits, B'beta and B'delta, recruit PP2A into a complex with TrkA to dephosphorylate the NGF receptor on Ser/Thr residues and to potentiate its intrinsic Tyr kinase activity. Acting at the receptor level, PP2A/ B'beta and B'delta enhance NGF (but not epidermal growth factor or fibroblast growth factor) signaling through the Akt and Ras-mitogen-activated protein kinase cascades and promote neuritogenesis and differentiation of PC12 cells. Thus, select PP2A heterotrimers oppose desensitization of the TrkA receptor tyrosine kinase, perhaps through dephosphorylation of inhibitory Ser/Thr phosphorylation sites on the receptor itself, to maintain neurotrophin-mediated developmental and survival signaling.

    Funded by: NINDS NIH HHS: NS43254, R01 NS043254

    Molecular and cellular biology 2009;29;3;662-74

  • Germline expression of H-Ras(G12V) causes neurological deficits associated to Costello syndrome.

    Viosca J, Schuhmacher AJ, Guerra C and Barco A

    Instituto de Neurociencias de Alicante (Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas), Campus de Sant Joan, Apt. 18, Sant Joan d'Alacant, 03550 Alicante, Spain.

    Costello syndrome (CS) is a rare congenital disorder caused by germline activation of H-Ras oncogenes. A mouse model of CS generated by introduction of an oncogenic Gly12Val mutation in the mouse H-Ras locus using homologous recombination in embryonic stem (ES) cells has been recently described. These mice phenocopied some of the abnormalities observed in patients with CS, including facial dysmorphia and cardiomyopathies. We investigated here their neurological and behavioral phenotype. The analysis of H-Ras(G12V) mice revealed phenotypes that resembled the hyperemotivity, hypersensibility and cognitive impairments observed in children with CS. Stronger neurological deficits were found in the analysis of mice homozygous for this mutation than in the analysis of heterozygous mice, suggesting the existence of a gene dose effect. These mice represent the first mouse model for CS, offering an experimental tool to study the molecular and physiological alterations underlying the neurological manifestations of CS and to test new therapies aimed at preventing or ameliorating the cognitive and emotional impairments associated to this condition.

    Genes, brain, and behavior 2009;8;1;60-71

  • Ligand-specific function of transforming growth factor beta in epithelial-mesenchymal transition in heart development.

    Azhar M, Runyan RB, Gard C, Sanford LP, Miller ML, Andringa A, Pawlowski S, Rajan S and Doetschman T

    BIO5 Institute, University of Arizona, Tucson, Arizona, USA. azharm@email.arizona.edu

    The ligand specificity of transforming growth factor beta (TGFbeta) in vivo in mouse cardiac cushion epithelial-to-mesenchymal transition (EMT) is poorly understood. To elucidate the function of TGFbeta in cushion EMT, we analyzed Tgfb1(-/-), Tgfb2(-/-), and Tgfb3(-/-) mice between embryonic day (E) 9.5 and E14.5 using both in vitro and in vivo approaches. Atrioventricular (AV) canal collagen gel assays at E9.5 indicated normal EMT in both Tgfb1(-/-) and Tgfb3(-/-) mice. However, analysis of Tgfb2(-/-) AV explants at E9.5 and E10.5 indicated that EMT, but not cushion cell proliferation, was initially delayed but later remained persistent. This was concordant with the observation that Tgfb2(-/-) embryos, and not Tgfb1(-/-) or Tgfb3(-/-) embryos, develop enlarged cushions at E14.5 with elevated levels of well-validated indicators of EMT. Collectively, these data indicate that TGFbeta2, and not TGFbeta1 or TGFbeta3, mediates cardiac cushion EMT by promoting both the initiation and cessation of EMT.

    Funded by: NHLBI NIH HHS: R01 HL070174, R01 HL070174-04, R01 HL075633, R01 HL075633-01A1, R01 HL082851, R01 HL092508, R01 HL092508-01A1; NICHD NIH HHS: R01 HD026471, R01 HD026471-11A1, R01 HD026471-12, R01 HD026471-13, R01 HD026471-14, R01 HD026471-15, R01 HD26471, R01 HD82851; NIEHS NIH HHS: P30 ES006694

    Developmental dynamics : an official publication of the American Association of Anatomists 2009;238;2;431-42

  • Regulation of growth and survival of activated T cells by cell-transducing inhibitors of Ras.

    Malik NM, Gilroy DW and Kabouridis PS

    Biochemical Pharmacology, William Harvey Research Institute, Queen Mary's School of Medicine and Dentistry, London, United Kingdom.

    We describe the development of cell-penetrating inhibitors of Ras and study their ability to inhibit T cell activation. The inhibitors transduced T cells in a time and concentration-dependent manner and interacted with endogenous Ras. Anti-CD3/CD28-activated cells when treated with the inhibitors, exhibited a notable reduction in cell size, diminished proliferative capacity, and were more prone to apoptosis. Similarly, lymphocytes activated by antigen in vivo, exhibited accelerated apoptosis when treated with the inhibitors ex vivo. Our data reveal a pro-survival role for Ras in activated primary T cells and describe a new methodology for regulating its activity.

    Funded by: Arthritis Research UK: 16018; Wellcome Trust: 087520

    FEBS letters 2009;583;1;61-9

  • LDLs stimulate p38 MAPKs and wound healing through SR-BI independently of Ras and PI3 kinase.

    Bulat N, Waeber G and Widmann C

    Department of Physiology and Department of Cell Biology and Morphology, Lausanne University, 1005 Lausanne, Switzerland.

    Intracellular signals elicited by LDLs are likely to play a role in the pathogenesis associated with increased LDL blood levels. We have previously determined that LDL stimulation of human skin fibroblasts, used as a model system for adventitial fibroblasts, activates p38 mitogen-activated protein kinases (MAPKs), followed by IL-8 production and increased wound-healing capacity of the cells. The proximal events triggering these responses had not been characterized, however. Here we show that MAPK kinases MKK3 and MKK6, but not MKK4, are the upstream kinases responsible for the activation of the p38 MAPKs and stimulation of wound closure in response to LDLs. Phosphoinositide 3 kinases (PI3Ks) and Ras have been suggested to participate in lipoprotein-induced MAPK activation. However, specific PI3K inhibitors or expression of a dominant-negative form of Ras failed to blunt LDL-induced p38 MAPK activation. The classical LDL receptor does not participate in LDL signaling, but the contribution of other candidate lipoprotein receptors has not been investigated. Using cells derived from scavenger receptor class B type I (SR-BI) knockout mice or the BLT-1 SR-BI inhibitor, we now show that this receptor is required for LDLs to stimulate p38 MAPKs and to promote wound healing. Identification of MKK3/6 and SR-BI as cellular relays in LDL-mediated p38 activation further defines the signaling events that could participate in LDL-mediated pathophysiological responses.

    Journal of lipid research 2009;50;1;81-9

  • Regulator of G-protein signaling 14 (RGS14) is a selective H-Ras effector.

    Willard FS, Willard MD, Kimple AJ, Soundararajan M, Oestreich EA, Li X, Sowa NA, Kimple RJ, Doyle DA, Der CJ, Zylka MJ, Snider WD and Siderovski DP

    Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, United States of America.

    Background: Regulator of G-protein signaling (RGS) proteins have been well-described as accelerators of Galpha-mediated GTP hydrolysis ("GTPase-accelerating proteins" or GAPs). However, RGS proteins with complex domain architectures are now known to regulate much more than Galpha GTPase activity. RGS14 contains tandem Ras-binding domains that have been reported to bind to Rap- but not Ras GTPases in vitro, leading to the suggestion that RGS14 is a Rap-specific effector. However, more recent data from mammals and Drosophila imply that, in vivo, RGS14 may instead be an effector of Ras.

    Full-length and truncated forms of purified RGS14 protein were found to bind indiscriminately in vitro to both Rap- and Ras-family GTPases, consistent with prior literature reports. In stark contrast, however, we found that in a cellular context RGS14 selectively binds to activated H-Ras and not to Rap isoforms. Co-transfection / co-immunoprecipitation experiments demonstrated the ability of full-length RGS14 to assemble a multiprotein complex with components of the ERK MAPK pathway in a manner dependent on activated H-Ras. Small interfering RNA-mediated knockdown of RGS14 inhibited both nerve growth factor- and basic fibrobast growth factor-mediated neuronal differentiation of PC12 cells, a process which is known to be dependent on Ras-ERK signaling.

    In cells, RGS14 facilitates the formation of a selective Ras.GTP-Raf-MEK-ERK multiprotein complex to promote sustained ERK activation and regulate H-Ras-dependent neuritogenesis. This cellular function for RGS14 is similar but distinct from that recently described for its closely-related paralogue, RGS12, which shares the tandem Ras-binding domain architecture with RGS14.

    Funded by: NCI NIH HHS: R01 CA127152, R01CA127152; NIGMS NIH HHS: R01 GM074268, R01GM074268; NINDS NIH HHS: R01 NS060725, R01 NS060725-01, R01 NS060725-02, R01 NS060725-03, R01 NS060725-04, R01NS060725; Wellcome Trust

    PloS one 2009;4;3;e4884

  • Serum-dependent transcriptional networks identify distinct functional roles for H-Ras and N-Ras during initial stages of the cell cycle.

    Castellano E, Guerrero C, Núñez A, De Las Rivas J and Santos E

    Centro de Investigación del Cáncer, IBMCC (CSIC-USAL), University of Salamanca, Campus Unamuno, 37007 Salamanca, Spain. Esther.Castellano@cancer.org.uk

    Background: Using oligonucleotide microarrays, we compared transcriptional profiles corresponding to the initial cell cycle stages of mouse fibroblasts lacking the small GTPases H-Ras and/or N-Ras with those of matching, wild-type controls.

    Results: Serum-starved wild-type and knockout ras fibroblasts had very similar transcriptional profiles, indicating that H-Ras and N-Ras do not significantly control transcriptional responses to serum deprivation stress. In contrast, genomic disruption of H-ras or N-ras, individually or in combination, determined specific differential gene expression profiles in response to post-starvation stimulation with serum for 1 hour (G0/G1 transition) or 8 hours (mid-G1 progression). The absence of N-Ras caused significantly higher changes than the absence of H-Ras in the wave of transcriptional activation linked to G0/G1 transition. In contrast, the absence of H-Ras affected the profile of the transcriptional wave detected during G1 progression more strongly than did the absence of N-Ras. H-Ras was predominantly functionally associated with growth and proliferation, whereas N-Ras had a closer link to the regulation of development, the cell cycle, immunomodulation and apoptosis. Mechanistic analysis indicated that extracellular signal-regulated kinase (ERK)-dependent activation of signal transducer and activator of transcription 1 (Stat1) mediates the regulatory effect of N-Ras on defense and immunity, whereas the pro-apoptotic effects of N-Ras are mediated through ERK and p38 mitogen-activated protein kinase signaling.

    Conclusions: Our observations confirm the notion of an absolute requirement for different peaks of Ras activity during the initial stages of the cell cycle and document the functional specificity of H-Ras and N-Ras during those processes.

    Genome biology 2009;10;11;R123

  • A cross-talk between oncogenic Ras and tumor suppressor PTEN through FAK Tyr861 phosphorylation in NIH/3T3 mouse embryonic fibroblasts.

    Bahk YY, Cho IH and Kim TS

    Protein Network Research Center, Yonsei University, 134, Shinchon-Dong, Seodeamoon-Gu, Seoul 120-749, Republic of Korea. bahk12@empal.com

    Although Ras is a potent oncogene, its tumorigenicity depends on cellular context and cooperative events. Tumor suppressor PTEN is the most important negative regulator of the cell-survival signaling pathway initiated by phosphoinositide 3-OH kinase. Previously, we established various NIH/3T3 cells expressing H-Ras mutant proteins. This report shows that expression of PTEN is suppressed by the oncogenic H-Ras at its protein and transcript levels as well as by oncogenic K- and N-Ras. This activity of oncogenic Ras is mediated by Raf-1/Erk/MEK signaling pathway. In our previous reports, FAK Y(861) phosphorylation is higher in H-Ras transformed NIH/3T3 cells. In this report, level of FAK pY(861) was examined in Ras mutant cell lines. By generating wild-type PTEN, lipid phosphatase-deficient PTEN and activity-inert PTEN-inducible cell lines in the background of oncogenic H-Ras stable expression in NIH/3T3 cells, we show level of FAK pY(861) is decreased by protein phosphatase activity of PTEN.

    Biochemical and biophysical research communications 2008;377;4;1199-204

  • 8-Oxoguanine-mediated transcriptional mutagenesis causes Ras activation in mammalian cells.

    Saxowsky TT, Meadows KL, Klungland A and Doetsch PW

    Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.

    8-Oxoguanine (8OG) is efficiently bypassed by RNA polymerases in vitro and in bacterial cells in vivo, leading to mutant transcripts by directing incorporation of an incorrect nucleotide during transcription. Such transcriptional mutagenesis (TM) may produce a pool of mutant proteins. In contrast, transcription-coupled repair safeguards against DNA damage, contingent upon the ability of lesions to arrest elongating RNA polymerase. In mammalian cells, the Cockayne syndrome B protein (Csb) mediates transcription-coupled repair, and its involvement in the repair of 8OG is controversial. The DNA glycosylase Ogg1 initiates base excision repair of 8OG, but its influence on TM is unknown. We have developed a mammalian system for TM in congenic mouse embryonic fibroblasts (MEFs), either WT or deficient in Ogg1 (ogg(-/-)), Csb (csb(-/-)), or both. This system uses expression of the Ras oncogene in which an 8OG replaces guanine in codon 61. Repair of 8OG restores the WT sequence; however, bypass and misinsertion opposite this lesion during transcription leads to a constitutively active mutant Ras protein and activation of downstream signaling events, including increased phosphorylation of ERK kinase. Upon transfection of MEFs with replication-incompetent 8OG constructs, we observed a marked increase in phospho-ERK in ogg(-/-) and csb(-/-)ogg(-/-) cells at 6 h, indicating persistence of the lesion and the occurrence of TM. This effect is absent in WT and csb(-/-) cells, suggesting rapid repair. These studies provide evidence that 8OG causes TM in mammalian cells, leading to a phenotypic change with important implications for the role of TM in tumorigenesis.

    Funded by: NCI NIH HHS: CA112982, CA120288

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;48;18877-82

  • Pak1 regulates multiple c-Kit mediated Ras-MAPK gain-in-function phenotypes in Nf1+/- mast cells.

    McDaniel AS, Allen JD, Park SJ, Jaffer ZM, Michels EG, Burgin SJ, Chen S, Bessler WK, Hofmann C, Ingram DA, Chernoff J and Clapp DW

    Department of Microbiology and Immunology, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, USA.

    Neurofibromatosis type 1 (NF1) is a common genetic disorder caused by mutations in the NF1 locus, which encodes neurofibromin, a negative regulator of Ras. Patients with NF1 develop numerous neurofibromas, which contain many inflammatory mast cells that contribute to tumor formation. Subsequent to c-Kit stimulation, signaling from Ras to Rac1/2 to the MAPK pathway appears to be responsible for multiple hyperactive mast cell phenotypes; however, the specific effectors that mediate these functions remain uncertain. p21-activated kinase 1 (Pak1) is a downstream mediator of Rac1/2 that has been implicated as a positive regulator of MAPK pathway members and is a modulator of cell growth and cytoskeletal dynamics. Using an intercross of Pak 1(-/-) mice with Nf1(+/-) mice, we determined that Pak1 regulates hyperactive Ras-dependent proliferation via a Pak1/Erk pathway, whereas a Pak1/p38 pathway is required for the increased migration in Nf1(+/-) mast cells. Furthermore, we confirmed that loss of Pak1 corrects the dermal accumulation of Nf1(+/-) mast cells in vivo to levels found in wild-type mice. Thus, Pak1 is a novel mast cell mediator that functions as a key node in the MAPK signaling network and potential therapeutic target in NF1 patients.

    Funded by: NCI NIH HHS: R01 CA074177, R01 CA117884, R01 CA74177; NIDDK NIH HHS: T32 DK007519, T32 DK007519-23; NINDS NIH HHS: F30 NS060322, F30 NS060322-01, P50 NS052606

    Blood 2008;112;12;4646-54

  • Ras signaling influences permissiveness of malignant peripheral nerve sheath tumor cells to oncolytic herpes.

    Farassati F, Pan W, Yamoutpour F, Henke S, Piedra M, Frahm S, Al-Tawil S, Mangrum WI, Parada LF, Rabkin SD, Martuza RL and Kurtz A

    Department of Medicine, Division of Hematology, Oncology, and Transplantation, Kansas University Medical Center, Kansas City, KS 66160, USA. ffarassati@kumc.edu

    Lack of expression of neurofibromin in neurofibromatosis 1 and its lethal derivative, malignant peripheral nerve sheath tumors (MPNSTs), is thought to result in the overactivation of the Ras signaling pathway. Our previous studies have shown that cells with overactivation in the Ras pathway are more permissive to infection with herpes simplex virus 1 and its mutant version R3616. In this study, we show that among five different mouse MPNST cell lines, only the ones with elevated levels of Ras signaling are highly permissive to infection with oncolytic herpes G207. Specific inhibitors of the Ras, ERK, and JNK pathways all reduced the synthesis of viral proteins in MPNST cells. The cell lines that contained lower levels of Ras and decreased activation of downstream signaling components underwent an enhancement in apoptosis upon exposure to G207. Additionally, mouse SW10 Schwann cells were able to become infected by parental herpes but were found to be resistant to G207. The immortalization of these cell lines with the expression of SV40 large T antigen increased the levels of Ras activation and permissiveness to oncolytic herpes. A Ras/Raf kinase inhibitor reduced the synthesis of both herpes simplex virus-1 and G207 proteins in SW10 cells. The results of this study, therefore, introduce Ras signaling as a divergent turning point for the response of MPNST cells to an assault by oncolytic herpes.

    Funded by: NINDS NIH HHS: R01-NS032677

    The American journal of pathology 2008;173;6;1861-72

  • Stimulation of Ebola virus production from persistent infection through activation of the Ras/MAPK pathway.

    Strong JE, Wong G, Jones SE, Grolla A, Theriault S, Kobinger GP and Feldmann H

    Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB,Canada R3E 3R2. jim_strong@phac-aspc.gc.ca

    Human infections with Ebola virus (EBOV) result in a deadly viral disease known as Ebola hemorrhagic fever. Up to 90% of infected patients die, and there is no available treatment or vaccine. The sporadic human outbreaks are believed to result when EBOV "jumps" from an infected animal to a person and is subsequently transmitted between persons by direct contact with infected blood or body fluids. This study was undertaken to investigate the mechanism by which EBOV can persistently infect and then escape from model cell and animal reservoir systems. We report a model system in which infection of mouse and bat cell lines with EBOV leads to persistence, which can be broken with low levels of lipopolysaccharide or phorbol-12-myristate-13-acetate (PMA). This reactivation depends on the Ras/MAPK pathway through inhibition of RNA-dependent protein kinase and eukaryotic initiation factor 2alpha phosphorylation and occurs at the level of protein synthesis. EBOV also can be evoked from mice 7 days after infection by PMA treatment, indicating that a similar mechanism occurs in vivo. Our findings suggest that EBOV may persist in nature through subclinical infection of a reservoir species, such as bats, and that appropriate physiological stimulation may result in increased replication and transmission to new hosts. Identification of a presumptive mechanism responsible for EBOV emergence from its reservoir underscores the "hit-and-run" nature of the initiation of human and/or nonhuman primate EBOV outbreaks and may provide insight into possible countermeasures to interfere with transmission.

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;46;17982-7

  • C/EBPbeta represses p53 to promote cell survival downstream of DNA damage independent of oncogenic Ras and p19(Arf).

    Ewing SJ, Zhu S, Zhu F, House JS and Smart RC

    Cell Signaling and Cancer Group, Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695-7633, USA.

    CCAAT/enhancer-binding protein-beta (C/EBPbeta) is a mediator of cell survival and tumorigenesis. When C/EBPbeta(-/-) mice are treated with carcinogens that produce oncogenic Ras mutations in keratinocytes, they respond with abnormally elevated keratinocyte apoptosis and a block in skin tumorigenesis. Although this aberrant carcinogen-induced apoptosis results from abnormal upregulation of p53, it is not known whether upregulated p53 results from oncogenic Ras and its ability to induce p19(Arf) and/or activate DNA-damage response pathways or from direct carcinogen-induced DNA damage. We report that p19(Arf) is dramatically elevated in C/EBPbeta(-/-) epidermis and that C/EBPbeta represses a p19(Arf) promoter reporter. To determine whether p19(Arf) is responsible for the proapoptotic phenotype in C/EBPbeta(-/-) mice, C/EBPbeta(-/-);p19(Arf-/-) mice were generated. C/EBPbeta(-/-);p19(Arf-/-) mice responded to carcinogen treatment with increased p53 and apoptosis, indicating p19(Arf) is not essential. To ascertain whether oncogenic Ras activation induces aberrant p53 and apoptosis in C/EBPbeta(-/-) epidermis, we generated K14-ER:Ras;C/EBPbeta(-/-) mice. Oncogenic Ras activation induced by 4-hydroxytamoxifen did not produce increased p53 or apoptosis. Finally, when C/EBPbeta(-/-) mice were treated with differing types of DNA-damaging agents, including alkylating chemotherapeutic agents, they displayed aberrant levels of p53 and apoptosis. These results indicate that C/EBPbeta represses p53 to promote cell survival downstream of DNA damage and suggest that inhibition of C/EBPbeta may be a target for cancer cotherapy to increase the efficacy of alkylating chemotherapeutic agents.

    Funded by: NCI NIH HHS: CA046637, R01 CA046637; NIEHS NIH HHS: ES012473, R01 ES012473

    Cell death and differentiation 2008;15;11;1734-44

  • p21 Ras/impedes mitogenic signal propagation regulates cytokine production and migration in CD4 T cells.

    Czyzyk J, Chen HC, Bottomly K and Flavell RA

    Departments of Pathology and Immunobiology.

    The propensity of T cells to generate coordinated cytokine responses is critical for the host to develop resistance to pathogens while maintaining the state of immunotolerance to self-antigens. The exact mechanisms responsible for preventing the overproduction of proinflammatory cytokines including interferon (IFN)-gamma are not fully understood, however. In this study, we examined the role of a recently described Ras GTPase effector and repressor of the Raf/MEK/ERK cascade called impedes mitogenic signal propagation (Imp) in limiting the induction of T-cell cytokines. We found that stimulation of the T cell receptor complex leads to the rapid development of a physical association between Ras and Imp. Consistent with the hypothesis that Imp inhibits signal transduction, we also found that disengagement of this molecule by the Ras(V12G37) effector loop mutant or RNA interference markedly enhances the activation of the NFAT transcription factor and IFN-gamma secretion. A strong output of IFN-gamma is responsible for the distinct lymphocyte traffic pattern observed in vivo because the transgenic or retroviral expression of Ras(V12G37) caused T cells to accumulate preferentially in the lymph nodes and delayed their escape from the lymphoid tissue, respectively. Together, our results describe a hitherto unrecognized negative regulatory role for Imp in the production of IFN-gamma in T cells and point to Ras-Imp binding as an attractive target for therapeutic interventions in conditions involving the production of this inflammatory cytokine.

    Funded by: PHS HHS: R01 5R37A102679-1

    The Journal of biological chemistry 2008;283;34;23004-15

  • Mouse mesenchymal stem cells expressing PAX-FKHR form alveolar rhabdomyosarcomas by cooperating with secondary mutations.

    Ren YX, Finckenstein FG, Abdueva DA, Shahbazian V, Chung B, Weinberg KI, Triche TJ, Shimada H and Anderson MJ

    Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, CA 90027, USA.

    Alveolar rhabdomyosarcomas (ARMS) are highly malignant soft-tissue sarcomas that arise in children, adolescents, and young adults. Although formation and expression of the PAX-FKHR fusion genes is thought to be the initiating event in this cancer, the role of PAX-FKHR in the neoplastic process remains largely unknown in a progenitor cell that is undefined. We hypothesize that PAX-FKHR determine the ARMS progenitor to the skeletal muscle lineage, which when coupled to the inactivation and/or activation of critical cell signaling pathways leads to the formation of ARMS. Because a number of studies have proposed that mesenchymal stem cells (MSC) are the progenitor for several of the sarcomas, we tested this hypothesis in MSCs. We show that PAX-FKHR induce skeletal myogenesis in MSCs by transactivating MyoD and myogenin. Despite exhibiting enhanced growth in vitro, the PAX-FKHR-expressing populations do not form colonies in soft agar or tumors in mice. Expression of dominant-negative p53, or the SV40 early region, elicits tumor formation in some of the PAX-FKHR-expressing populations. Additional activation of the Ras signaling pathway leads to highly malignant tumor formation for all of the populations. The PAX-FKHR-expressing tumors were shown to have histologic, immunohistochemical, and gene expression profiles similar to human ARMS. Our results show the critical role played by PAX-FKHR in determining the molecular, myogenic, and histologic phenotype of ARMS. More importantly, we identify MSCs as a progenitor that can give rise to ARMS.

    Cancer research 2008;68;16;6587-97

  • IQGAP3 regulates cell proliferation through the Ras/ERK signalling cascade.

    Nojima H, Adachi M, Matsui T, Okawa K, Tsukita S and Tsukita S

    Laboratory of Biological Science, Graduate School of Frontier Biosciences/Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.

    Proliferation of epithelial cells must be spatiotemporally regulated to maintain the organization of epithelial sheets. Here we show that the IQGAP family, comprising IQGAP1, 2 and 3, underlies lateral cell-cell contacts of epithelial cells. Of the three proteins, IQGAP3 is unique in that its expression is specifically confined to proliferating cells. Knockdown of IQGAP3 in cultured epithelial cells caused inhibition of proliferation and ERK activity. When exogenously expressed in quiescent cells, IQGAP3 was capable of inducing cell-cycle re-entry, which was completely inhibited by the MEK inhibitor U0126. Thus, IQGAP3 is necessary and sufficient for driving cell proliferation and ERK acts downstream of IQGAP3. Furthermore, IQGAP3 specifically interacted with the active, GTP-bound form of Ras, and in IQGAP3 knockdown cells, the activity of Ras, but not of other small GTPases, was inhibited. Thus, IQGAP3 regulates the promotion of cell proliferation through Ras-dependent ERK activation.

    Nature cell biology 2008;10;8;971-8

  • Mycoplasma infection suppresses p53, activates NF-kappaB and cooperates with oncogenic Ras in rodent fibroblast transformation.

    Logunov DY, Scheblyakov DV, Zubkova OV, Shmarov MM, Rakovskaya IV, Gurova KV, Tararova ND, Burdelya LG, Naroditsky BS, Ginzburg AL and Gudkov AV

    Gamaleya Research Institute for Epidemiology and Microbiology, Moscow, Russia.

    Prokaryotes of the genus Mycoplasma are the smallest cellular organisms that persist as obligate extracellular parasites. Although mycoplasma infection is known to be associated with chromosomal instability and can promote malignant transformation, the mechanisms underlying these phenomena remain unknown. Since persistence of many cellular parasites requires suppression of apoptosis in host cells, we tested the effect of mycoplasma infection on the activity of the p53 and nuclear factor (NF)-kappaB pathways, major mechanisms controlling programmed cell death. To monitor the activity of p53 and NF-kappaB in mycoplasma-infected cells, we used a panel of reporter cell lines expressing the bacterial beta-galactosidase gene under the control of p53- or NF-kappaB-responsive promoters. Cells incubated with media conditioned with different species of mycoplasma showed constitutive activation of NF-kappaB and reduced activation of p53, common characteristics of the majority of human tumor cells, with M. arginini having the strongest effect among the species tested. Moreover, mycoplasma infection reduced the expression level and inducibility of an endogenous p53-responsive gene, p21(waf1), and inhibited apoptosis induced by genotoxic stress. Infection with M. arginini made rat and mouse embryo fibroblasts susceptible to transformation with oncogenic H-Ras, whereas mycoplasma-free cells underwent irreversible p53-dependent growth arrest. Mycoplasma infection was as effective as shRNA-mediated knockdown of p53 expression in making rodent fibroblasts permissive to Ras-induced transformation. These observations indicate that mycoplasma infection plays the role of a p53-suppressing oncogene that cooperates with Ras in cell transformation and suggest that the carcinogenic and mutagenic effects of mycoplasma might be due to inhibition of p53 tumor suppressor function by this common human parasite.

    Funded by: NCI NIH HHS: CA098374, CA60730, CA75179, R01 CA060730, R01 CA075179, R01 CA098374

    Oncogene 2008;27;33;4521-31

  • Ras signaling mechanisms underlying impaired GluR1-dependent plasticity associated with fragile X syndrome.

    Hu H, Qin Y, Bochorishvili G, Zhu Y, van Aelst L and Zhu JJ

    Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.

    Fragile X syndrome, caused by the loss of FMR1 gene function and loss of fragile X mental retardation protein (FMRP), is the most commonly inherited form of mental retardation. The syndrome is characterized by associative learning deficits, reduced risk of cancer, dendritic spine dysmorphogenesis, and facial dysmorphism. However, the molecular mechanism that links loss of function of FMR1 to the learning disability remains unclear. Here, we report an examination of small GTPase Ras signaling and synaptic AMPA receptor (AMPA-R) trafficking in cultured slices and intact brains of wild-type and FMR1 knock-out mice. In FMR1 knock-out mice, synaptic delivery of GluR1-, but not GluR2L- and GluR4-containing AMPA-Rs is impaired, resulting in a selective loss of GluR1-dependent long-term synaptic potentiation (LTP). Although Ras activity is upregulated, its downstream MEK (extracellular signal-regulated kinase kinase)-ERK (extracellular signal-regulated kinase) signaling appears normal, and phosphoinositide 3-kinase (PI3K)-protein kinase B (PKB; or Akt) signaling is compromised in FMR1 knock-out mice. Enhancing Ras-PI3K-PKB signaling restores synaptic delivery of GluR1-containing AMPA-Rs and normal LTP in FMR1 knock-out mice. These results suggest aberrant Ras signaling as a novel mechanism for fragile X syndrome and indicate manipulating Ras-PI3K-PKB signaling to be a potentially effective approach for treating patients with fragile X syndrome.

    Funded by: NIMH NIH HHS: R01 MH082808, R01 MH082808-05; NINDS NIH HHS: R01 NS051241, R01 NS051241-03, R01 NS053570

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2008;28;31;7847-62

  • Ras-MAPK signaling promotes trophectoderm formation from embryonic stem cells and mouse embryos.

    Lu CW, Yabuuchi A, Chen L, Viswanathan S, Kim K and Daley GQ

    Division of Pediatric Hematology and Oncology, Children's Hospital Boston and Dana Faber Cancer Institute, Boston, Massachusetts 02115, USA.

    In blastocyst chimeras, embryonic stem (ES) cells contribute to embryonic tissues but not extraembryonic trophectoderm. Conditional activation of HRas1(Q61L) in ES cells in vitro induces the trophectoderm marker Cdx2 and enables derivation of trophoblast stem (TS) cell lines that, when injected into blastocysts, chimerize placental tissues. Erk2, the downstream effector of Ras-mitogen-activated protein kinase (MAPK) signaling, is asymmetrically expressed in the apical membranes of the 8-cell-stage embryo just before morula compaction. Inhibition of MAPK signaling in cultured mouse embryos compromises Cdx2 expression, delays blastocyst development and reduces trophectoderm outgrowth from embryo explants. These data show that ectopic Ras activation can divert ES cells toward extraembryonic trophoblastic fates and implicate Ras-MAPK signaling in promoting trophectoderm formation from mouse embryos.

    Funded by: Howard Hughes Medical Institute; NIDDK NIH HHS: R01 DK059279, R01 DK059279-06, R01 DK070055, R01 DK070055-01; NIH HHS: DP1 OD000256, DP1 OD000256-01

    Nature genetics 2008;40;7;921-6

  • Loss of miRNA biogenesis induces p19Arf-p53 signaling and senescence in primary cells.

    Mudhasani R, Zhu Z, Hutvagner G, Eischen CM, Lyle S, Hall LL, Lawrence JB, Imbalzano AN and Jones SN

    Department of Cell Biology, University of Massachusetts Medical School, North Worcester, MA 01655, USA.

    Dicer, an enzyme involved in microRNA (miRNA) maturation, is required for proper cell differentiation and embryogenesis in mammals. Recent evidence indicates that Dicer and miRNA may also regulate tumorigenesis. To better characterize the role of miRNA in primary cell growth, we generated Dicer-conditional mice. Ablation of Dicer and loss of mature miRNAs in embryonic fibroblasts up-regulated p19(Arf) and p53 levels, inhibited cell proliferation, and induced a premature senescence phenotype that was also observed in vivo after Dicer ablation in the developing limb and in adult skin. Furthermore, deletion of the Ink4a/Arf or p53 locus could rescue fibroblasts from premature senescence induced by Dicer ablation. Although levels of Ras and Myc oncoproteins appeared unaltered, loss of Dicer resulted in increased DNA damage and p53 activity in these cells. These results reveal that loss of miRNA biogenesis activates a DNA damage checkpoint, up-regulates p19(Arf)-p53 signaling, and induces senescence in primary cells.

    Funded by: NCI NIH HHS: CA098193, CA77735, R01 CA077735, R01 CA098139, R01 CA098193, R56 CA077735; NIDDK NIH HHS: DK73324, R21 DK073324

    The Journal of cell biology 2008;181;7;1055-63

  • H-ras regulates angiogenesis and vascular permeability by activation of distinct downstream effectors.

    Serban D, Leng J and Cheresh D

    Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, USA.

    Angiogenesis and vascular permeability occur following endothelium activation by vascular endothelial growth factor (VEGF). Downstream mechanisms that define these vascular responses remain unknown. H-Ras activation has been associated with the angiogenic response. However, active H-Ras initiates a wide spectrum of other biological responses through multiple downstream effectors. To identify vascular signaling by H-Ras and the immediate effectors we activated the extracellular signal regulated kinase/mitogen-activated protein kinase or phosphatidylinositol 3-kinase (PI3K) pathways in chicken and mouse endothelial tissues by ectopic expression of the Ras effector mutants H-RasV12S35 or H-RasV12C40, respectively. Constitutive activation of the extracellular signal-regulate kinase/mitogen-activated protein kinase pathway by H-RasV12S35 was sufficient to induce angiogenesis and not vascular permeability, whereas activation of the PI3K pathway by H-RasV12C40 was required for both angiogenesis and vascular permeability. Pharmacological inhibition of PI3K (alpha/beta) suppressed both Ras- or VEGF-mediated vascular response in vivo and survival of primary human endothelial cells in vitro. However, inhibition of PI3K (gamma/delta) suppressed Ras- or VEGF-mediated vascular permeability in vivo, with no effect on survival of primary endothelial cells. This was supported by genetic studies because PI3K p110gamma knockout mice showed impaired vascular permeability response to VEGF or H-RasV12C40 treatment yet produced a wild-type angiogenic response to H-RasV12S35. We conclude that downstream of VEGF, H-Ras serves as a cellular switch that controls neovascularization and vascular permeability by activation of distinct effectors.

    Funded by: NCI NIH HHS: CA45726, CA50286, P01 CA078045, P01 CA078045-100004, R01 CA045726, R01 CA045726-14S1, R01 CA050286, R01 CA095262, R01 CA095262-06, R01 CA095262-09, R37 CA050286, R37 CA050286-19; NHLBI NIH HHS: P01 HL057900, P01 HL057900-130006, R01 HL078912, R01 HL078912-04

    Circulation research 2008;102;11;1350-8

  • The Rb/E2F pathway and Ras activation regulate RecQ helicase gene expression.

    Liu Y, El-Naggar S, Clem B, Chesney J and Dean DC

    Molecular Targets Program, James Graham Brown Cancer Center, Louisville, KY 40202, USA.

    Disruption of the Rb (retinoblastoma protein)/E2F cell-cycle pathway and Ras activation are two of the most frequent events in cancer, and both of these mutations place oncogenic stress on cells to increase DNA replication. In the present study, we demonstrate that these mutations have an additive effect on induction of members of the RecQ DNA helicase family. RecQ activity is important for genomic stability, initiation of DNA replication and telomere maintenance, and mutation of the BLM (Bloom's syndrome gene), WRN (Werner's syndrome gene) or RECQL4 (Rothmund-Thomson syndrome gene) family members leads to premature aging syndromes characterized by genetic instability and telomere loss. RecQ family members are frequently overexpressed in cancers, and overexpression of BLM has been shown to cause telomere elongation. Concomitant with induction of RecQ genes in response to Rb family mutation and Ras activation, we show an increase in the number of telomeric repeats. We suggest that this induction of RecQ genes in response to common oncogenic mutations may explain the up-regulation of the genes seen in cancers, and it may provide a means for transformed cells to respond to an increased demand for DNA replication.

    Funded by: NCRR NIH HHS: RR 018733

    The Biochemical journal 2008;412;2;299-306

  • A mouse model for Costello syndrome reveals an Ang II-mediated hypertensive condition.

    Schuhmacher AJ, Guerra C, Sauzeau V, Cañamero M, Bustelo XR and Barbacid M

    Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas, Madrid, Spain.

    Germline activation of H-RAS oncogenes is the primary cause of Costello syndrome (CS), a neuro-cardio-facio-cutaneous developmental syndrome. Here we describe the generation of a mouse model of CS by introduction of an oncogenic Gly12Val mutation in the mouse H-Ras locus using homologous recombination in ES cells. Germline expression of the endogenous H-RasG12V oncogene, even in homozygosis, resulted in hyperplasia of the mammary gland. However, development of tumors in these mice was rare. H-RasG12V mutant mice closely phenocopied some of the abnormalities observed in patients with CS, including facial dysmorphia and cardiomyopathies. These mice also displayed alterations in the homeostasis of the cardiovascular system, including development of systemic hypertension, extensive vascular remodeling, and fibrosis in both the heart and the kidneys. This phenotype was age dependent and was a consequence of the abnormal upregulation of the renin-Ang II system. Treatment with captopril, an inhibitor of Ang II biosynthesis, prevented development of the hypertension condition, vascular remodeling, and heart and kidney fibrosis. In addition, it partially alleviated the observed cardiomyopathies. These mice should help in elucidating the etiology of CS symptoms, identifying additional defects, and evaluating potential therapeutic strategies.

    Funded by: NCI NIH HHS: 5R01-CA73735-10, R01 CA073735

    The Journal of clinical investigation 2008;118;6;2169-79

  • Enhanced Ras activity preserves dendritic size and extension as well as synaptic contacts of neurons after functional deprivation in synRas mice.

    Alpár A, Naumann N, Härtig W, Arendt T and Gärtner U

    Department of Anatomy, Histology and Embryology, Semmelweis University Medical School, Tuzoltó u. 58, H-1450 Budapest, Hungary. dralpar@gmx.net

    The monomeric GTP-binding protein p21Ras has been repeatedly implicated in neuronal stability and plastic changes of the adult nervous system. Recently, we have shown that expression of constitutively active Ras protein in transgenic synRas mice results in a significant increase in the dendritic size and complexity of differentiated pyramidal neurons as well as in increased synaptic connectivity. In the present study, we examined the organization of the vibrissae-barrel cortex in synRas mice and the effects of enhanced Ras activity on deprivation-induced dendritic reorganization after vibrissectomy. The results demonstrate a significant increase in vibrissae-barrel sizes and proportional spacing between barrels in synRas mice, suggesting that the neuronal target specificity of thalamocortical terminals is preserved. Accordingly, the arrangement of double bouquet cells at the borders of barrel columns ensuring functional distinctness is unchanged. Partial vibrissectomy is followed by significant dendritic regression of corresponding pyramidal neurons in the barrel cortex of wild-type mice, which, however, could not be observed in synRas mice. The results provide the first evidence for a role of Ras in preserving neuronal structure after functional deprivation in vivo.

    The European journal of neuroscience 2008;27;12;3083-94

  • Partial functional overlap of the three ras genes in mouse embryonic development.

    Nakamura K, Ichise H, Nakao K, Hatta T, Otani H, Sakagami H, Kondo H and Katsuki M

    Mouse Genome Technology Laboratory, Mitsubishi Kagaku Institute of Life Sciences, Machida, Tokyo, Japan.

    In mammals, three ras genes, H-ras, N-ras and K-ras, encode homologous but distinct 21-kDa Ras proteins. We examined the in vivo functional relationship of the three ras genes in mouse embryonic development by investigating the phenotypes of mice deficient in one or multiple ras genes. H-ras-/- mice and N-ras-/- mice as well as a substantial proportion of H-ras-/-/N-ras-/- mice expressing only the K-ras gene were viable, while K-ras-/- mice were embryonically lethal, as have been reported previously. N-ras-/-/K-ras+/- mice died neonatally, while H-ras-/-/K-ras-/- embryos died much earlier than K-ras homozygous mutant fetuses. To further investigate the functional relationship of the ras genes in embryonic development, we introduced a human H-ras transgene into single or multiple ras mutant mice and found that the transgene rescued mice, including triple ras mutants, from embryonic lethality in association with correction of thin ventricular walls of the heart in null K-ras mutant mice. In situ hybridization revealed that the expression of the H-ras transgene on embryonic day E13.5 and E15.5 was more intense in major organs, including the heart, than those of endogenous ras genes. We therefore conclude that the functions of the ras genes are partially overlapping in mouse embryonic development.

    Oncogene 2008;27;21;2961-8

  • Oncogenicity of DNA in vivo: tumor induction with expression plasmids for activated H-ras and c-myc.

    Sheng L, Cai F, Zhu Y, Pal A, Athanasiou M, Orrison B, Blair DG, Hughes SH, Coffin JM, Lewis AM and Peden K

    Division of Viral Products, OVRR, CBER, FDA, Building 29A, Room 3D08, 29 Lincoln Drive, Bethesda, MD 20892, USA.

    All vaccines and other biological products contain contaminating residual DNA derived from the production cell substrate. Whether this residual cell-substrate DNA can induce tumors in vaccine recipients and thus represent a risk factor has been debated for over 50 years without resolution. As a first step in resolving this issue, we have generated expression plasmids for the activated human H-ras oncogene and for the murine c-myc proto-oncogene. Their oncogenic activity was confirmed in vitro using the focus-formation transformation assay. Two strains of adult and newborn immune-competent mice were inoculated with different amounts of either plasmid alone or with a combination of the H-ras and c-myc plasmids. Tumors developed only in mice inoculated with both plasmids and only at the highest amount of DNA (12.5 microg of each plasmid). The NIH Swiss mouse was more sensitive than the C57BL/6 mouse, and newborn animals were more sensitive than adults. Cell lines were established from the tumors. PCR and Southern hybridization analyses demonstrated that both inoculated oncogenes were present in all of the tumor-derived cell lines and that the cells in the tumors were clonal. Western analysis demonstrated that both oncoproteins were expressed in these cell lines. These results demonstrate that cellular oncogenes can induce tumors following subcutaneous inoculation. Such information provides a possible way of evaluating and estimating the theoretical oncogenic risk posed by residual cell-substrate DNA in vaccines.

    Biologicals : journal of the International Association of Biological Standardization 2008;36;3;184-97

  • Ras signaling directs endothelial specification of VEGFR2+ vascular progenitor cells.

    Kawasaki K, Watabe T, Sase H, Hirashima M, Koide H, Morishita Y, Yuki K, Sasaoka T, Suda T, Katsuki M, Miyazono K and Miyazawa K

    Department of Molecular Pathology, Graduate School of Medicine, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan.

    Vascular endothelial growth factor receptor 2 (VEGFR2) transmits signals of crucial importance to vasculogenesis, including proliferation, migration, and differentiation of vascular progenitor cells. Embryonic stem cell-derived VEGFR2(+) mesodermal cells differentiate into mural lineage in the presence of platelet derived growth factor (PDGF)-BB or serum but into endothelial lineage in response to VEGF-A. We found that inhibition of H-Ras function by a farnesyltransferase inhibitor or a knockdown technique results in selective suppression of VEGF-A-induced endothelial specification. Experiments with ex vivo whole-embryo culture as well as analysis of H-ras(-/-) mice also supported this conclusion. Furthermore, expression of a constitutively active H-Ras[G12V] in VEGFR2(+) progenitor cells resulted in endothelial differentiation through the extracellular signal-related kinase (Erk) pathway. Both VEGF-A and PDGF-BB activated Ras in VEGFR2(+) progenitor cells 5 min after treatment. However, VEGF-A, but not PDGF-BB, activated Ras 6-9 h after treatment, preceding the induction of endothelial markers. VEGF-A thus activates temporally distinct Ras-Erk signaling to direct endothelial specification of VEGFR2(+) vascular progenitor cells.

    The Journal of cell biology 2008;181;1;131-41

  • p204 protein is a novel modulator of ras activity.

    Ding B and Lengyel P

    Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8024, USA.

    The murine p200 family protein, p204, modulates cell proliferation and tissue differentiation. Many of its activities are exerted in the nucleus. However, in cardiac myocytes, p204 accumulated in the cytoplasm. A yeast two-hybrid assay revealed a p204-cytoplasmic Ras protein interaction. This was confirmed (i) by coimmunoprecipitation of p204 with Ras in mouse heart extract and with endogenous or ectopic H-Ras and K-Ras in cell lysates as well as (ii) by binding of purified H-Ras-GTP to purified p204 in vitro. p204 inhibited (i) the cleavage of RasGTP to RasGDP by RasGAP; (ii) the binding to RasGTP of Raf-1, phosphatidylinositol 3-kinase, and Ral-GDS, effectors of Ras signaling; and (iii) activation by the Ras pathway of the phosphorylation and thus activation of downstream targets (e.g. MEK, Akt, and p38 MAPK). Oncogenic Ras expression triggered the phosphorylation and translocation of p204 from the nucleus to the cytoplasm. This is expected to increase the interaction between the two proteins. Translocation triggered by Ras oncoprotein was blocked by the LY294002 inhibitor of phosphatidylinositol 3-kinase. Ras did not promote phosphorylation or translocation to the cytoplasm of mutated p204 in which serine 179 was replaced by alanine. p204 overexpression inhibited the anchorage-independent proliferation of cells expressing Ras(Q61L) oncoprotein. Ras oncoprotein triggered in MEF3T3 cells the rearrangement of the actin cytoskeleton and the enhancement of cell migration through a membrane. Overexpression of p204 inhibited both. Ras oncoprotein or activated, wild-type Ras was described to increase Egr-1 transcription factor expression. We report that a sequence in the gene encoding p204 bound Egr-1, and Egr-1 activated p204 expression. Ras oncoprotein or activated wild-type Ras increased the expression in 3T3 cells of p204 together with that of Egr-1. Furthermore, the activation of expression of a single copy of K-ras oncogene in cultured murine embryonic cells induced the expression of a high level of p204 as well as its distribution between the nuclei and the cytoplasm. Thus, p204 may serve as a negative feedback inhibitor of Ras activity.

    Funded by: NIAID NIH HHS: AI12320

    The Journal of biological chemistry 2008;283;9;5831-48

  • Nuclear exclusion of forkhead box O and Elk1 and activation of nuclear factor-kappaB are required for C2C12-RasV12C40 myoblast differentiation.

    De Alvaro C, Nieto-Vazquez I, Rojas JM and Lorenzo M

    Departamento de Bioquimica y Biologia Molecular II, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain. mlorenzo@farm.ucm.es.

    Activating ras point mutations are frequently found in skeletal muscle tumors such as rhabdomyosarcomas. In this study we investigated the impact of two different H-ras mutants in skeletal muscle differentiation: RasV12, a constitutively active form, and RasV12C40, a mutant deficient in Raf1 activation. Stably transfected C2C12-RasV12 myoblasts actively proliferated as indicated by the sustained expression of proliferating cell nuclear antigen and retinoblastoma at the hyperphosphorylated state and failed to express differentiation markers. This differentiation-defective phenotype was a consequence of the chronic p44/p42MAPK phosphorylation and the inability of the cells to activate AKT. Moreover, we observed that p44/p42MAPK activation in C2C12-RasV12 myoblasts phosphorylated the ETS-like transcription factor (ELK) 1, which translocates to the nuclei and seemed to be involved in maintaining myoblast proliferation. C2C12-RasV12C40 myoblasts cultured in low serum repressed phosphorylation of p44/p42MAPK and ELK1, resulting in cell cycle arrest and myogenic differentiation. Under this condition, activation of AKT, p70S6K, and p38MAPK was produced, leading to formation of myotubes in 3 d, 1 d earlier than in control C2C12-AU5 cells. Moreover, the expression of muscle-specific proteins, mainly the terminal differentiation markers caveolin-3 and myosin heavy chain, also occurred 1 d earlier than in control cells. Furthermore, AKT activation produced phosphorylation of Forkhead box O that led to nuclear exclusion and inactivation, allowing myogenesis. In addition, we found an induction of nuclear factor-kappaB activity in the nucleus in C2C12-RasV12C40 myotubes attributed to p38MAPK activation. Accordingly, muscle differentiation is associated with a pattern of transcription factors that involves nuclear exclusion ELK1 and Forkhead box O and the increase in nuclear factor-kappaB DNA binding.

    Endocrinology 2008;149;2;793-801

  • Brain cancer stem-like cell genesis from p53-deficient mouse astrocytes by oncogenic Ras.

    Lee JS, Gil JE, Kim JH, Kim TK, Jin X, Oh SY, Sohn YW, Jeon HM, Park HJ, Park JW, Shin YJ, Chung YG, Lee JB, You S and Kim H

    Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713, Republic of Korea.

    Here, we show that H-ras(V12) causes the p53-knockout mouse astrocytes (p53-/- astrocytes) to be transformed into brain cancer stem-like cells. H-ras(V12) triggers the p53-/- astrocytes to express a Nestin and a Cd133, which are expressed in normal and cancer neural stem cells. H-ras(V12) also induces the formation of a single cell-derived neurosphere under neural stem cell culture conditions. Furthermore, H-ras(V12)-overexpressing p53-/- astrocytes (p53-/-ast-H-ras(V12)) possess an in vitro self-renewal capacity, and are aberrantly differentiated into Tuj1-positve neurons both in vitro and in vivo. Amongst a variety of Ras-mediated canonical signaling pathways, we demonstrated that the MEK/ERK signaling pathway is responsible for neurosphere formation in p53-deficient astrocytes, whereas the PI3K/AKT signaling pathway is involved in oncogenic transformation in these cells. These findings suggest that the activation of Ras signaling pathways promotes the generation of brain cancer stem-like cells from p53-deficient mouse astrocytes by changing cell fate and transforming cell properties.

    Biochemical and biophysical research communications 2008;365;3;496-502

  • The LIM-only protein FHL2 mediates ras-induced transformation through cyclin D1 and p53 pathways.

    Labalette C, Nouët Y, Levillayer F, Armengol C, Renard CA, Soubigou G, Xia T, Buendia MA and Wei Y

    Institut Pasteur, Unité d'Oncogenèse et Virologie Moléculaire, Paris, France.

    Background: Four and a half LIM-only protein 2 (FHL2) has been implicated in multiple signaling pathways that regulate cell growth and tissue homeostasis. We reported previously that FHL2 regulates cyclin D1 expression and that immortalized FHL2-null mouse embryo fibroblasts (MEFs) display reduced levels of cyclin D1 and low proliferative activity.

    Here we address the contribution of FHL2 in cell transformation by investigating the effects of oncogenic Ras in FHL2-null context. We show that H-RasV12 provokes cell cycle arrest accompanied by accumulation of p53 and p16(INK4a) in immortalized FHL2(-/-) MEFs. These features contrast sharply with Ras transforming activity in wild type cell lines. We further show that establishment of FHL2-null cell lines differs from conventional immortalization scheme by retaining functional p19(ARF)/p53 checkpoint that is required for cell cycle arrest imposed by Ras. However, after serial passages of Ras-expressing FHL2(-/-) cells, dramatic increase in the levels of D-type cyclins and Rb phosphorylation correlates with the onset of cell proliferation and transformation without disrupting the p19(ARF)/p53 pathway. Interestingly, primary FHL2-null cells overexpressing cyclin D1 undergo a classical immortalization process leading to loss of the p19(ARF)/p53 checkpoint and susceptibility to Ras transformation.

    Our findings uncover a novel aspect of cellular responses to mitogenic stimulation and illustrate a critical role of FHL2 in the signalling network that implicates Ras, cyclin D1 and p53.

    PloS one 2008;3;11;e3761

  • Cooperation of Ha-ras and Bcl-2 during multistep skin carcinogenesis.

    Lee S, Chari NS, Kim HW, Wang X, Roop DR, Cho SH, DiGiovanni J and McDonnell TJ

    Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.

    Nonmelanoma skin cancer (NMSC) is the most frequently diagnosed cancer in the United States. Deregulation of bcl-2 and ras family members is commonly observed in NMSC. It has been previously demonstrated that simultaneous bcl-2 and Ha-ras gene expression in keratinocytes results in disordered differentiation and resistance to cell death induced by ultraviolet (UV) radiation. It was, therefore, interest to assess the extent of cooperation between bcl-2 and Ha-ras during multistep skin carcinogenesis. The keratin 1 promoter was used to generate HK1.ras and HK1.bcl-2 transgenic mice, which were subsequently crossed to generate HK1.ras/bcl-2 double transgenic mice. The apoptotic index (AI) following UV-irradiation was significantly lower in HK1.bcl-2 and HKI.ras/bcl-2 epidermis compared to control littermates. Interestingly, the AI of HK1.ras/bcl-2 mice was significantly lower than even HK1.bcl-2 mice following UV-irradiation. To investigate the interaction of these oncogenes in skin tumorigenesis, a two-stage chemical carcinogenesis protocol was used to induce tumors. The individual contributions of Ha-ras and bcl-2 to papilloma latency, incidence, and growth rate in HK1.ras/bcl-2 double transgenic mice was marginally additive. Papillomas arising in HK1.ras transgenic mice exhibited the highest rate of apoptosis whereas papillomas arising in the HK1.ras/bcl-2 double transgenic mice exhibited rates of apoptosis that were significantly lower than papillomas arising in either control littermate or HK1.ras mice. Constitutive expression of either Ha-ras or bcl-2 exhibited similar rates of malignant tumor progression and they were not significantly different than control littermates. Importantly, when these two oncoproteins were coexpressed, a significant, and synergistic, increase in malignant transformation was observed.

    Funded by: NCI NIH HHS: T32 CA67759, UO1 CA105491, UO1 CA83701

    Molecular carcinogenesis 2007;46;12;949-57

  • Very-KIND, a KIND domain containing RasGEF, controls dendrite growth by linking Ras small GTPases and MAP2.

    Huang J, Furuya A and Furuichi T

    Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.

    The regulation of cytoskeletal components in the dendritic shaft core is critical for dendrite elongation and branching. Here, we report that a brain-specific Ras guanine nucleotide exchange factor (RasGEF) carrying two kinase non-catalytic C-lobe domains (KINDs), very-KIND (v-KIND), regulates microtubule-associated protein 2 (MAP2). v-KIND is expressed in developing mouse brain, predominantly in the cerebellar granule cells. v-KIND not only activates Ras small GTPases via the C-terminal RasGEF domain, but also specifically binds to MAP2 via the second KIND domain (KIND2), leading to threonine phosphorylation of MAP2. v-KIND overexpression suppresses dendritic extension and branching of hippocampal neurons and cerebellar granule cells, whereas knockdown of endogenous v-KIND expression promotes dendrite growth. These findings suggest that v-KIND mediates a signaling pathway that links Ras and MAP2 to control dendrite growth.

    The Journal of cell biology 2007;179;3;539-52

  • Transcriptomal profiling of site-specific Ras signals.

    Agudo-Ibáñez L, Núñez F, Calvo F, Berenjeno IM, Bustelo XR and Crespo P

    Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas (CSIC), Departamento de Biología Molecular, Unidad de Biomedicina, CSIC-Universidad de Cantabria, Santander, Spain.

    Ras proteins are distributed in distinct plasma-membrane microdomains and endomembranes. The biochemical signals generated by Ras therein differ qualitatively and quantitatively, but the extent to which this spatial variability impacts on the genetic program switched-on by Ras is unknown. We have used microarray technology to identify the transcriptional targets of localization-specific Ras subsignals in NIH3T3 cells expressing H-RasV12 selectively tethered to distinct cellular microenvironments. We report that the transcriptomes resulting from site-specific Ras activation show a significant overlap. However, distinct genetic signatures can also be found for each of the Ras subsignals. Our analyses unveil 121 genes uniquely regulated by Ras signals emanating from plasma-membrane microdomains. Interestingly, not a single gene is specifically controlled by lipid raft-anchored Ras. Furthermore, only 9 genes are exclusive for Ras signals from endomembranes. Also, we have identified 31 genes common to the site-specific Ras subsignals capable of inducing cellular transformation. Among these are the genes coding for Vitamin D receptor and for p120-GAP and we have assessed their impact in Ras-induced transformation. Overall, this report reveals the complexity and variability of the different genetic programs orchestrated by Ras from its main sublocalizations.

    Funded by: NCI NIH HHS: 5 R01 CA73735-10, R01 CA073735, R01 CA073735-10

    Cellular signalling 2007;19;11;2264-76

  • The RAS-dependent ERF control of cell proliferation and differentiation is mediated by c-Myc repression.

    Verykokakis M, Papadaki C, Vorgia E, Le Gallic L and Mavrothalassitis G

    Medical School, University of Crete and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, 710 03, Greece.

    The ERF transcriptional repressor is a downstream effector of the RAS/ERK pathway that interacts with and is directly phosphorylated by ERKs in vivo and in vitro. This phosphorylation results in its cytoplasmic export and inactivation, although lack of ERK activity allows its immediate nuclear accumulation and repressor function. Nuclear ERFs arrest cell cycle progression in G(1) and can suppress ras-dependent tumorigenicity. Here we provide evidence that ERF function is mediated by its ability to repress transcription of c-Myc. Promoter reporter assays indicate a DNA binding-dependent and repressor domain-dependent Myc transcriptional repression. Chromatin immunoprecipitations in primary cells suggest that ERF specifically binds on the c-Myc promoter in an E2F4/5-dependent manner and only under conditions that the physiological c-Myc transcription is stopped. Cellular systems overexpressing nuclear ERF exhibit reduced c-Myc mRNA and tumorigenic potential. Elimination of Erf in animal models results in increased c-Myc expression, whereas Erf(-)(/)(-) primary fibroblasts fail to down-regulate Myc in response to growth factor withdrawal. Finally, elimination of c-Myc in primary mouse embryo fibroblasts negates the ability of nuclear ERF to suppress proliferation. Thus Erf provides a direct link between the RAS/ERK signaling and the transcriptional regulation of c-Myc and suggests that RAS/ERK attenuation actively regulates cell fate.

    The Journal of biological chemistry 2007;282;41;30285-94

  • Neurofibromatosis-1 regulates neuronal and glial cell differentiation from neuroglial progenitors in vivo by both cAMP- and Ras-dependent mechanisms.

    Hegedus B, Dasgupta B, Shin JE, Emnett RJ, Hart-Mahon EK, Elghazi L, Bernal-Mizrachi E and Gutmann DH

    Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.

    Individuals with neurofibromatosis type 1 (NF1) develop abnormalities of both neuronal and glial cell lineages, suggesting that the NF1 protein neurofibromin is an essential regulator of neuroglial progenitor function. In this regard, Nf1-deficient embryonic telencephalic neurospheres exhibit increased self-renewal and prolonged survival as explants in vivo. Using a newly developed brain lipid binding protein (BLBP)-Cre mouse strain to study the role of neurofibromin in neural progenitor cell function in the intact animal, we now show that neuroglial progenitor Nf1 inactivation results in increased glial lineage proliferation and abnormal neuronal differentiation in vivo. Whereas the glial cell lineage abnormalities are recapitulated by activated Ras or Akt expression in vivo, the neuronal abnormalities were Ras- and Akt independent and reflected impaired cAMP generation in Nf1-deficient cells in vivo and in vitro. Together, these findings demonstrate that neurofibromin is required for normal glial and neuronal development involving separable Ras-dependent and cAMP-dependent mechanisms.

    Funded by: NCI NIH HHS: 1-UO1-CA84314; NIDDK NIH HHS: R03 DK068028, R03 DK068028-01

    Cell stem cell 2007;1;4;443-57

  • Ancestral bias in the Hras1 gene and distal Chromosome 7 among inbred mice.

    Drew JC, Kastenmeier AS and Drinkwater NR

    McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, 1400 University Avenue, Madison, Wisconsin 53706, USA.

    Inbred strains of mice vary in their frequency of liver tumors initiated by a mutation in the Hras1 (H-ras) proto-oncogene. We sequenced 4.5 kb of the Hras1 gene on distal Chr 7 in a diverse set of 12 commonly used laboratory inbred strains of mice and detected no sequence variation to account for strain-specific differences in Hras1 mutation prevalence. Furthermore, the Hras1 sequence is essentially monoallelic for an ancestral gene derived from the M. m. domesticus species. To determine if the monoallelism and associated low rate of polymorphism are unique to Hras1 or representative of the general chromosomal locale, we extended the sequence analysis to 12 genes in the final 8 Mb of distal Chr 7. A region of at least 2.5 Mb that encompasses several genes, including Hras1 and the H19/Igf2 loci, demonstrates virtually no sequence variation. The 12 inbred strains share one dominant haplotype derived from the M. m. domesticus allele. Chromosomal regions flanking the monoallelic segment exhibit a significantly higher rate of variation and multiple haplotypes, a majority of which are attributed to M. m. domesticus or M. m. musculus ancestry.

    Funded by: NCI NIH HHS: CA009135, CA22484, P01 CA022484, T32 CA009135

    Mammalian genome : official journal of the International Mammalian Genome Society 2007;18;10;732-8

  • Effects of dietary calorie restriction or exercise on the PI3K and Ras signaling pathways in the skin of mice.

    Xie L, Jiang Y, Ouyang P, Chen J, Doan H, Herndon B, Sylvester JE, Zhang K, Molteni A, Reichle M, Zhang R, Haub MD, Baybutt RC and Wang W

    Department of Human Nutrition and Statistics, Kansas State University, Manhattan, Kansas 66506, USA.

    Weight control by exercise and dietary calorie restriction (DCR) has been associated with reduced cancer risk, but the underlying mechanisms are not well understood. This study was designed to compare the effects of weight loss by increasing physical activity or decreasing calorie intake on tumor promoter-induced Ras-MAPK and PI3K-Akt pathways. SENCAR mice were randomly assigned to one of the following five groups: ad libitum-fed sedentary control, ad libitum-fed exercise (AL+Exe), exercise but pair-fed at the amount as controls (PF+Exe), 20% DCR, and 20% DCR plus exercise (DCR+Exe). After 10 weeks, body weight and body fat significantly decreased in the groups of DCR, DCR+Exe, and PF+Exe when compared with the controls. AL+Exe did not induce weight loss due to, at least in part, increased food intake. Plasma IGF-1 levels reduced significantly in DCR and DCR+Exe but not PF+Exe. The protein H-Ras and activated Ras-GTP significantly decreased in TPA-induced skin tissues of DCR-fed mice but not exercised mice. PI3K protein, phosphoserine Akt, and p42/p44-MAPK were reduced, however, in both DCR and PF+Exe groups. Immunohistochemistry demonstrated that the significantly reduced H-Ras occurred in subcutaneous fat cells, while the reduced PI3K and PCNA took place only in the epidermis. Plasma leptin decreased in PF+Exe, DCR, and DCR+Exe, while the caspase-3 activity increased in DCR+Exe only. Genomic microarray analysis further indicated that the expression of 34 genes relevant to PI3K and 31 genes to the MAPK pathway were significantly regulated by either DCR or PF+Exe treatments. The reduced PI3K in PF+Exe mice was partially reversed by IGF-1 treatment. The overall results of this study demonstrated that DCR abrogated both Ras and PI3K signaling, which might inhibit TPA-induced proliferation and anti-apoptosis. Selective inhibition of PI3K by PF+Exe but not AL+Exe seems more attributable to the magnitude of the caloric deficit and/or body fat loss than diet versus exercise comparison.

    Funded by: NCI NIH HHS: R01 CA106397; NCRR NIH HHS: P20 RR15563

    The Journal of biological chemistry 2007;282;38;28025-35

  • Serum components and activated Ha-ras antagonize expression of perivenous marker genes stimulated by beta-catenin signaling in mouse hepatocytes.

    Braeuning A, Menzel M, Kleinschnitz EM, Harada N, Tamai Y, Köhle C, Buchmann A and Schwarz M

    Institute of Pharmacology und Toxicology, Department of Toxicology, University of Tuebingen, Germany.

    Hepatocytes of the periportal and perivenous zones of the liver lobule show marked differences in the contents and activities of many enzymes and other proteins. Previous studies from our and other groups have pointed towards an important role of beta-catenin-dependent signaling in the regulation of expression of genes encoding proteins with preferential perivenous localization, whereas, in contrast, signaling through Ras-dependent pathway(s) may induce a 'periportal' phenotype. We have now conducted a series of experiments to further investigate this hypothesis. In transgenic mice with scattered expression of an activated Ha-ras (Ha-ras(G12V)) mutant in liver, expression of the perivenous markers glutamine synthetase and two cytochrome P450 isoforms was completely abolished in those hepatocytes demonstrating constitutively activated extracellular signal-regulated kinase activity, even though they were located directly adjacent to central veins. Similarly, incubation of primary hepatocytes or hepatoma cells with increasing amounts of serum caused a concentration-dependent attenuation of expression of perivenous marker mRNAs, whereas the expression of periportal markers was increased. The inhibitory effect of high amounts of serum on the expression of perivenous markers was also observed if their expression was stimulated by activation of beta-catenin signaling, and comparable inhibitory effects were seen in cells stably transfected with a T-cell factor/lymphoid-enhancing factor-driven luciferase reporter. Epidermal growth factor could partly mimic serum effects in hepatoma cells, and its effect could be blocked by an inhibitor of extracellular signal-regulated kinase activity. These data suggest that activation of the Ras/mitogen-activated protein kinase (extracellular signal-regulated kinase) pathway favors periportal gene expression while simultaneously antagonizing a perivenous phenotype of hepatocytes.

    The FEBS journal 2007;274;18;4766-77

  • H-Ras does not need COP I- or COP II-dependent vesicular transport to reach the plasma membrane.

    Zheng H, McKay J and Buss JE

    Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA.

    Although vesicular transport of the H-Ras protein from the Golgi to the plasma membrane is well known, additional trafficking steps, both to and from the plasma membrane, have also been described. Notably, both vesicular and nonvesicular transport mechanisms have been proposed. The initial trafficking of H-Ras to the plasma membrane was therefore examined in more detail. In untreated cells, H-Ras appeared at the plasma membrane more rapidly than a protein carried by the conventional exocytic pathway, and no H-Ras was visible on Golgi membranes in >80% of the cells. H-Ras was still able to reach the plasma membrane when COP II-directed transport was disrupted by two different mutant forms of Sar1, when COP I-mediated vesicular traffic from the endoplasmic reticulum to the Golgi was inhibited with brefeldin A, or when microtubules were disrupted by nocodazole. Although some H-Ras was present in the secretory pathway, protein that reached the membranes of the endoplasmic reticulum-Golgi intermediate compartment was unable to move further in the presence of nocodozale. These results identify an alternative mechanism for H-Ras trafficking that circumvents conventional COPI-, COPII-, and microtubule-dependent vesicular transport. Thus, H-Ras has two simultaneous but distinct means of transport and need not depend on vesicular trafficking for its delivery to the plasma membrane.

    The Journal of biological chemistry 2007;282;35;25760-8

  • Mechanical stress-mediated Runx2 activation is dependent on Ras/ERK1/2 MAPK signaling in osteoblasts.

    Kanno T, Takahashi T, Tsujisawa T, Ariyoshi W and Nishihara T

    Division of Oral and Maxillofacial Reconstructive Surgery, Department of Oral and Maxillofacial Surgery, Science of Physical Functions, Kyushu Dental College, Fukuoka, Japan.

    The sequence of biochemical events involved in mechanical stress-induced signaling in osteoblastic cells remains unclear. Runx2, a transcription factor involved in the control of osteoblast differentiation, has been identified as a target of mechanical stress-induced signaling in osteoblastic cells. In this study, uniaxial sinusoidal stretching (15% strain, 115% peak-to-peak, at 1/12 Hz) stimulated the differentiation of osteoblast-like MC3T3-E1 cells and rat primary osteoblastic cells by activating Runx2. We examined the involvement of diverse mitogen-activated protein kinase (MAPK) pathways in the activation of Runx2 during mechanical stress. Mechanical stress increased alkaline phosphatase activity, a marker of osteoblast differentiation, increased the expression of the osteoblast-specific extracellular matrix (ECM) protein osteocalcin, and induced Runx2 activation, along with increased osterix expression. Furthermore, activation of ERK1/2 and p38 MAPKs increased significantly. U0126, a selective inhibitor of ERK1/2, completely blocked Runx2 activation during periods of mechanical stress, but the p38 MAPK-selective inhibitor SB203580 did not alter nuclear phosphorylation of Runx2. Small interfering RNA (siRNA) targeting Rous sarcoma kinase (RAS), an upstream regulator of both ERK1/2 and p38 MAPKs, inhibited stretch-induced ERK1/2 activation, but not mechanically induced p38 MAPK activity. Furthermore, mechanically induced Runx2 activation was inhibited by Ras depletion, using siRNA. These findings indicate that mechanical stress regulates Runx2 activation and favors osteoblast differentiation through the activation of MAPK signal transduction pathways and Ras/Raf-dependent ERK1/2 activation, independent of p38 MAPK signaling.

    Journal of cellular biochemistry 2007;101;5;1266-77

  • Hemizygous disruption of Cdc25A inhibits cellular transformation and mammary tumorigenesis in mice.

    Ray D, Terao Y, Nimbalkar D, Hirai H, Osmundson EC, Zou X, Franks R, Christov K and Kiyokawa H

    Department of Molecular Pharmacology and Biological Chemistry, and Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 E. Superior Street, Chicago, IL 60611, USA.

    CDC25A phosphatase activates multiple cyclin-dependent kinases (CDK) during cell cycle progression. Inactivation of CDC25A by ubiquitin-mediated degradation is a major mechanism of DNA damage-induced S-G(2) checkpoint. Although increased CDC25A expression has been reported in various human cancer tissues, it remains unclear whether CDC25A activation is a critical rate-limiting step of carcinogenesis. To assess the role for CDC25A in cell cycle control and carcinogenesis, we used a Cdc25A-null mouse strain we recently generated. Whereas Cdc25A(-/-) mice exhibit early embryonic lethality, Cdc25A(+/-) mice show no appreciable developmental defect. Cdc25A(+/-) mouse embryonic fibroblasts (MEF) exhibit normal kinetics of cell cycle progression at early passages, modestly enhanced G(2) checkpoint response to DNA damage, and shortened proliferative life span, compared with wild-type MEFs. Importantly, Cdc25A(+/-) MEFs are significantly resistant to malignant transformation induced by coexpression of H-ras(V12) and a dominant negative p53 mutant. The rate-limiting role for CDC25A in transformation is further supported by decreased transformation efficiency in MCF-10A human mammary epithelial cells stably expressing CDC25A small interfering RNA. Consistently, Cdc25A(+/-) mice show substantially prolonged latency in mammary tumorigenesis induced by MMTV-H-ras or MMTV-neu transgene, whereas MMTV-myc-induced tumorigenesis is not significantly affected by Cdc25A heterozygosity. Mammary tissues of Cdc25A(+/-);MMTV-neu mice before tumor development display less proliferative response to the oncogene with increased tyrosine phosphorylation of CDK1/2, but show no significant change in apoptosis. These results suggest that Cdc25A plays a rate-limiting role in transformation and tumor initiation mediated by ras activation.

    Funded by: NCI NIH HHS: CA 112282, R01 CA 100204; NICHD NIH HHS: HD 38085, U54 HD 40093

    Cancer research 2007;67;14;6605-11

  • Tumour prevention by a single antibody domain targeting the interaction of signal transduction proteins with RAS.

    Tanaka T, Williams RL and Rabbitts TH

    MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK.

    Many disease-related processes occur via protein complexes that are considered undruggable with small molecules. An example is RAS, which is frequently mutated in cancer and contributes to initiation and maintenance of the disease by constitutive signal transduction through protein interaction with effector proteins, like PI3K, RAF and RALGDS. Such protein interactions are therefore significant targets for therapy. We describe a single immunoglobulin variable region domain that specifically binds to activated GTP-bound RAS and prevents RAS-dependent tumorigenesis in a mouse model. The crystal structure of the immunoglobulin-RAS complex shows that the variable region competitively binds to the conformationally variant regions of RAS, where its signalling effector molecules interact. This allows the plasma membrane targeted single domain intrabody to inhibit signalling by mutant RAS. This mode of action is a novel advance to directly interfere with oncogenic RAS function in human cancer and shows a universally applicable approach to develop macromolecules to combat cancer. In addition, this method illustrates a general means for interfering with protein interactions that are commonly considered intractable as conventional drug targets.

    Funded by: Medical Research Council: MC_U105178807, MC_U105184308

    The EMBO journal 2007;26;13;3250-9

  • Adhesion-related kinase induction of migration requires phosphatidylinositol-3-kinase and ras stimulation of rac activity in immortalized gonadotropin-releasing hormone neuronal cells.

    Nielsen-Preiss SM, Allen MP, Xu M, Linseman DA, Pawlowski JE, Bouchard RJ, Varnum BC, Heidenreich KA and Wierman ME

    Department of Medicine, the University of Colorado at Denver, Denver, CO 80220, USA.

    GnRH neurons migrate into the hypothalamus during development. Although migratory defects may result in disordered activation of the reproductive axis and lead to delayed or absent sexual maturation, specific factors regulating GnRH neuronal migration remain largely unknown. The receptor tyrosine kinase, adhesion-related kinase (Ark) (also known as Axl, UFO, and Tyro7), has been implicated in the migration of GnRH neuronal cells. Binding of its ligand, growth arrest-specific gene 6 (Gas6), promotes cytoskeletal remodeling and migration of NLT GnRH neuronal cells via Rac and p38 MAPK. Here, we examined the Axl effectors proximal to Rac in the signaling pathway. Gas6/Axl-induced lamellipodia formation and migration were blocked after phosphatidylinositol-3-kinase (PI3K) inhibition in GnRH neuronal cells. The p85 subunit of PI3K coimmunoprecipitated with Axl and was phosphorylated in a Gas6-sensitive manner. In addition, PI3K inhibition in GnRH neuronal cells diminished Gas6-induced Rac activation. Exogenous expression of a dominant-negative form of Ras also decreased GnRH neuronal lamellipodia formation, migration, and Rac activation. PI3K inhibition blocked Ras in addition to Rac activation and migration. In contrast, pharmacological blockade of the phospholipase C gamma effectors, protein kinase C or calcium/calmodulin protein kinase II, had no effect on Gas6/Axl signaling to promote Rac activation or stimulate cytoskeletal reorganization and migration. Together, these data show that the PI3K-Ras pathway is a major mediator of Axl actions upstream of Rac to induce GnRH neuronal cell migration.

    Funded by: NICHD NIH HHS: HD 08667, HD 31191; NINDS NIH HHS: NS 38619

    Endocrinology 2007;148;6;2806-14

  • The tumor suppressor neurofibromin confers sensitivity to apoptosis by Ras-dependent and Ras-independent pathways.

    Shapira S, Barkan B, Friedman E, Fridman E, Kloog Y and Stein R

    Department of Neurobiochemistry, George S Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.

    Neurofibromatosis type 1 (NF1) is characterized by a high incidence of benign and malignant tumors attributed to loss of function of Nf1, which encodes neurofibromin, a tumor suppressor with Ras-GAP activity. Neurofibromin deficiency typically causes chronic activation of Ras, considered the major contributor to manifestation of NF1. Resistance to radio- and chemotherapy are typical of NF1-associated tumors, but the underlying mechanism is unknown. Here, we investigated interrelationships between neurofibromin expression, Ras activity, and sensitivity to apoptosis. Neurofibromin-deficient mouse embryonic fibroblasts (MEFs) and human NF1 tumor cells were more resistant than neurofibromin-expressing cells to apoptosis. Moreover, Nf1(-/-), Nf1(+/-), and Nf1(+/+) MEFs exhibited gene-dosage-related resistance to apoptosis. Resistance of the Nf1-deficient cells was mediated by two survival pathways: a Ras-dependent pathway, and a Ras-independent pathway promoted by the lack of an NF1-GRD-independent proapoptotic action of neurofibromin. Therefore, besides its Ras-dependent growth inhibition, neurofibromin can exert tumor suppression via a proapoptotic effect.

    Cell death and differentiation 2007;14;5;895-906

  • The requirement of Ras and Rap1 for the activation of ERKs by cAMP, PACAP, and KCl in cerebellar granule cells.

    Obara Y, Horgan AM and Stork PJ

    Vollum Institute, L474, Oregon Health and Science University, Portland, Oregon 97239, USA.

    In cerebellar granule cells, the mitogen-activated protein kinase (MAPK) or extracellular signal-regulated kinase (ERK) cascade mediates multiple functions, including proliferation, differentiation, and survival. In these cells, ERKs are activated by diverse stimuli, including cyclic adenosine monophosphate (cAMP), pituitary adenylate cyclase activating protein (PACAP), depolarization induced by elevated extracellular potassium (KCl), and the neurotrophin brain-derived neurotrophic factor. Extensive studies in neuronal cell lines have implicated the small G proteins Ras and Rap1 in the activation of ERKs by cAMP, PACAP, and KCl. However, the requirement of Ras and Rap1 in these pathways in cerebellar granule cells has not been addressed. In this study, we utilize multiple biochemical assays to determine the mechanisms of action and requirement of Ras and Rap1 in cultured cerebellar granule cells. We show that both Ras and Rap1 can be activated by cAMP or PACAP via protein kinase (PKA)-dependent mechanisms. KCl activation of Ras also required PKA. Using both adenoviral and transgenic approaches, we show that Ras plays a major role in ERK activation by cAMP, PACAP, and KCl, while Rap1 also mediates activation of a selective membrane-associated pool of ERKs. Furthermore, Rap1, but not Ras, activation by PKA appears to require the action of Src family kinases.

    Funded by: NIMH NIH HHS: R01 MH59768; PHS HHS: F2N510895A

    Journal of neurochemistry 2007;101;2;470-82

  • Enhancement of dopaminergic properties and protection mediated by neuronal activation of Ras in mouse ventral mesencephalic neurones.

    Chakrabarty K, Serchov T, Mann SA, Dietzel ID and Heumann R

    Department of Molecular Neurobiochemistry, NC7/174, Ruhr University, 44780 Bochum, Germany.

    The poor differentiation and survival of dopaminergic neurones are practical constraints in their therapeutic applications. Here we explored the role of neuronally activated Ras in ventral mesencephalon-derived neurospheres generated from synRas mouse embryos. The expression of Val12 Ha-Ras transgene and enhanced Ras activity was evident after differentiation of the neurospheres with a corresponding activating phosphorylation of mitogen-activated protein kinase. Phosphorylation of Akt/PKB, the target kinase of phosphoinositide 3-kinase, along with phosphorylation of Bad and CREB were enhanced in synRas-derived differentiated neurosphere cultures. Furthermore, increased Nurr1 expression was associated with elevated numbers of dopaminergic neurones in synRas-derived cultures compared with the wild-type. Correspondingly, tyrosine hydroxylase promoter assays revealed enhanced transcriptional activation of the promoter in synRas-derived cultures. synRas-derived dopaminergic neurones were greatly resistant to degeneration induced by various noxious stimuli. Consistently, the transgenic expression of activated Ras attenuated the adverse 6-hydroxydopamine effects on dopaminergic neurones. Dopaminergic neurones derived from both wild-type and synRas cultures expressed voltage-gated potassium and sodium currents, fired action potentials and exhibited electrical network activity. Thus, expression of the transgene promotes survival and enhances differentiation towards a dopaminergic cell fate without altering their basic electrical properties. Our results suggest that intracellular cell therapy mimicking trophic signalling may offer potential benefit in models of human disease associated with dopamine neurone dysfunction.

    The European journal of neuroscience 2007;25;7;1971-81

  • H-ras inhibits RhoA/ROCK leading to a decrease in the basal tone in the internal anal sphincter.

    de Godoy MA, Patel CA, Waldman SA, Katsuki M, Regan RF and Rattan S

    Departments of Medicine, Division of Gastroenterology & Hepatology, Pharmacology and Experimental Therapeutics, and Emergency Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennyslvania 19107, USA.

    The present studies evaluated the role of H-ras and its implications in the RhoA/Rho kinase (ROCK) pathway in regulating basal tone in the internal anal sphincter (IAS).

    Methods: Studies were performed in the IAS from the wild-type (H-ras(+/+)) and knock-out (H-ras(-/-)) mice. The basal tone of smooth muscle strips was measured by isometric force transducers. Length of smooth muscle cells (SMC) isolated from the IAS in the basal state was determined by phase contrast microscopy. Experiments were repeated in the presence of Y 27632, a ROCK inhibitor. Involvement of the RhoA/ROCK machinery was analyzed by reverse-transcription polymerase chain reaction, Western blot, and immunocytochemistry. Reversal of H-ras knock-out effect was evaluated by transfection of SMCs with the constitutively activated (G12V) mutant.

    Results: Basal tone of the H-ras(-/-) IAS was significantly higher and resistant to relaxation by Y 27632, compared with the H-ras(+/+) IAS. Similarly, the length of SMCs from H-ras(-/-) IAS was significantly shorter. Y 27632 eliminated this difference. RhoA immunoreactivity shifted from cytoplasm to plasma membrane in H-ras(-/-) SMCs, a change typically associated with contraction. Further, SMCs from H-ras(-/-) mice exhibited higher levels of the contractile proteins ROCK II, phosphorylated-MYPT(1) and phosphorylated-MLC(20). Transfection with the G12V mutant increased the length of H-ras(-/-) cells. Conversely, the dominant negative H-ras (S17N) mutant decreased the length of H-ras(+/+) cells.

    Conclusions: H-ras negatively regulates basal tone in the IAS by inhibiting RhoA/Rho-kinase machinery. Studies may have significant relevance in the pathophysiology and therapy of certain anorectal motility disorders associated with the IAS dysfunction.

    Funded by: NIDDK NIH HHS: DK-35385

    Gastroenterology 2007;132;4;1401-9

  • p200 RhoGAP promotes cell proliferation by mediating cross-talk between Ras and Rho signaling pathways.

    Shang X, Moon SY and Zheng Y

    Division of Experimental Hematology, Children's Hospital Research Foundation, University of Cincinnati, Cincinnati, Ohio 45229, USA.

    p200 RhoGAP, a member of the Rho GTPase-activating protein (RhoGAP) family, was previously implicated in the regulation of neurite outgrowth through its RhoGAP activity. Here we show that ectopic expression of p200 RhoGAP stimulates fibroblast cell proliferation and cell cycle progression, leading to transformation. The morphology of the foci induced by p200 RhoGAP is distinct from that formed by Rac or Rho activation but similar to that induced by oncogenic Ras, raising the possibility that p200 RhoGAP may engage Ras signaling. Expression of p200 RhoGAP results in a significant increase of Ras-GTP and the activation of two downstream signaling pathways of Ras, ERK1/2 and phosphatidylinositol 3-kinase. Inhibition of Ras or ERK1/2, but not phosphatidylinositol 3-kinase, effectively suppresses the foci formation induced by p200 RhoGAP, suggesting that the Ras-ERK pathway is required for p200 RhoGAP-mediated cell transformation. p200 RhoGAP co-localizes with p120 RasGAP in cells and forms a complex with p120 RasGAP, and this interaction is mediated by the C-terminal region and the Src homology 3 domain of p200 RhoGAP and p120 RasGAP, respectively. Mutations of p200 RhoGAP that disrupt interaction with p120 RasGAP abolish its Ras activation and cell transforming activities. Interestingly, the RhoGAP activity of the N-terminal RhoGAP domain in p200 RhoGAP is also required for its full transforming activity, and expression of a dominant negative RhoA mutant that blocks RhoA cycling between the GDP- and GTP-bound states suppresses p200 RhoGAP transformation. These results suggest that a Rho GTPase-activating protein may have a positive input to cell proliferation and provide evidence that p200 RhoGAP can mediate cross-talks between Ras- and Rho-regulated signaling pathways in cell growth regulation.

    Funded by: NCI NIH HHS: CA105117; NIGMS NIH HHS: GM53943

    The Journal of biological chemistry 2007;282;12;8801-11

  • Diversity, parental germline origin, and phenotypic spectrum of de novo HRAS missense changes in Costello syndrome.

    Zampino G, Pantaleoni F, Carta C, Cobellis G, Vasta I, Neri C, Pogna EA, De Feo E, Delogu A, Sarkozy A, Atzeri F, Selicorni A, Rauen KA, Cytrynbaum CS, Weksberg R, Dallapiccola B, Ballabio A, Gelb BD, Neri G and Tartaglia M

    Istituto di Clinica Pediatrica, Università Cattolica del Sacro Cuore, Rome, Italy.

    Activating mutations in v-Ha-ras Harvey rat sarcoma viral oncogene homolog (HRAS) have recently been identified as the molecular cause underlying Costello syndrome (CS). To further investigate the phenotypic spectrum associated with germline HRAS mutations and characterize their molecular diversity, subjects with a diagnosis of CS (N = 9), Noonan syndrome (NS; N = 36), cardiofaciocutaneous syndrome (CFCS; N = 4), or with a phenotype suggestive of these conditions but without a definitive diagnosis (N = 12) were screened for the entire coding sequence of the gene. A de novo heterozygous HRAS change was detected in all the subjects diagnosed with CS, while no lesion was observed with any of the other phenotypes. While eight cases shared the recurrent c.34G>A change, a novel c.436G>A transition was observed in one individual. The latter affected residue, p.Ala146, which contributes to guanosine triphosphate (GTP)/guanosine diphosphate (GDP) binding, defining a novel class of activating HRAS lesions that perturb development. Clinical characterization indicated that p.Gly12Ser was associated with a homogeneous phenotype. By analyzing the genomic region flanking the HRAS mutations, we traced the parental origin of lesions in nine informative families and demonstrated that de novo mutations were inherited from the father in all cases. We noted an advanced age at conception in unaffected fathers transmitting the mutation.

    Funded by: NHLBI NIH HHS: HL71207; NICHD NIH HHS: HD01294, HD048502; Telethon: GGP04172

    Human mutation 2007;28;3;265-72

  • Promotion of Hras-induced squamous carcinomas by a polymorphic variant of the Patched gene in FVB mice.

    Wakabayashi Y, Mao JH, Brown K, Girardi M and Balmain A

    Cancer Research Institute, University of California at San Francisco, 2340 Sutter Street, San Francisco, California 94143, USA.

    Mice of the C57BL/6 strain are resistant to the development of skin squamous carcinomas (SCCs) induced by an activated Ras oncogene, whereas FVB/N mice are highly susceptible. The genetic basis of this difference in phenotype is unknown. Here we show that susceptibility to SCC is under the control of a carboxy-terminal polymorphism in the mouse Ptch gene. F1 hybrids between C57BL/6 and FVB/N strains ((B6FVB)F1) are resistant to Ras-induced SCCs, but resistance can be overcome either by elimination of the C57BL/6 Ptch allele (Ptch(B6)) or by overexpression of the FVB/N Ptch allele (Ptch(FVB)) in the epidermis of K5Hras-transgenic (B6FVB)F1 hybrid mice. The human Patched (PTCH) gene is a classical tumour suppressor gene for basal cell carcinomas and medulloblastomas, the loss of which causes increased signalling through the Sonic Hedgehog (SHH) pathway. SCCs that develop in PtchB6+/- mice do not lose the wild-type Ptch gene or show evidence of increased SHH signalling. Although Ptch(FVB) overexpression can promote SCC formation, continued expression is not required for tumour maintenance, suggesting a role at an early stage of tumour cell lineage commitment. The Ptch polymorphism affects Hras-induced apoptosis, and binding to Tid1, the mouse homologue of the Drosophila l(2)tid tumour suppressor gene. We propose that Ptch occupies a critical niche in determining basal or squamous cell lineage, and that both tumour types can arise from the same target cell depending on carcinogen exposure and host genetic background.

    Nature 2007;445;7129;761-5

  • Hyperactivation of Ha-ras oncogene, but not Ink4a/Arf deficiency, triggers bladder tumorigenesis.

    Mo L, Zheng X, Huang HY, Shapiro E, Lepor H, Cordon-Cardo C, Sun TT and Wu XR

    Department of Urology, New York University Cancer Institute, New York University School of Medicine, New York, New York, USA.

    Although ras is a potent mitogenic oncogene, its tumorigenicity depends on cellular context and cooperative events. Here we show that low-level expression of a constitutively active Ha-ras in mouse urothelium induces simple urothelial hyperplasia that is resistant to progression to full-fledged bladder tumors even in the absence of Ink4a/Arf. In stark contrast, doubling of the gene dosage of the activated Ha-ras triggered early-onset, rapidly growing, and 100% penetrant tumors throughout the urinary tract. Tumor initiation required superseding a rate-limiting step between simple and nodular hyperplasia, the latter of which is marked by the emergence of mesenchymal components and the coactivation of AKT and STAT pathways as well as PTEN inactivation. These results indicate that overactivation of Ha-ras is both necessary and sufficient to induce bladder tumors along a low-grade, noninvasive papillary pathway, and they shed light on the recent findings that ras activation, via point mutation, overexpression, or intensified signaling from FGF receptor 3, occurs in 70%-90% of these tumors in humans. Our results highlight the critical importance of the dosage/strength of Ha-ras activation in dictating its tumorigenicity--a mechanism of oncogene activation not fully appreciated to date. Finally, our results have clinical implications, as inhibiting ras and/or its downstream effectors, such as AKT and STAT3/5, could provide alternative means to treat low-grade, superficial papillary bladder tumors, the most common tumor in the urinary system.

    Funded by: NIDDK NIH HHS: DK52206, DK56903, DK69688

    The Journal of clinical investigation 2007;117;2;314-25

  • Activation of Ras up-regulates pro-apoptotic BNIP3 in nitric oxide-induced cell death.

    An HJ, Maeng O, Kang KH, Lee JO, Kim YS, Paik SG and Lee H

    Department of Biology, School of Biosciences and Biotechnology, Chungnam National University, Daejeon, Korea.

    Nitric oxide (NO) produced by NO synthases causes nitration and nitrosylation of cellular factors. We have shown previously that endogenously produced or exogenously added NO induces expression of BNIP3 (Bcl-2/adenovirus E1B 19 kDa-interacting protein 3), leading to death of macrophages (Yook, Y.-H., Kang, K.-H., Maeng, O., Kim, T.-R., Lee, J.-O., Kang, K.-i., Kim, Y.-S., Paik, S.-G., and Lee, H. (2004) Biochem. Biophys. Res. Commun. 321, 298-305). We now provide evidence that Ras mediates NO-induced BNIP3 expression via the MEK/ERK/hypoxia-inducible factor (HIF)-1 pathway. (a) ras-Q61L, a constitutively active form of Ras, up-regulated BNIP3 protein expression by enhancing Bnip3 promoter activity, and ras-S17N, a dominant-negative form, and ras-C118S, an S-nitrosylation mutant, blocked NO-induced BNIP3 expression, suggesting that Ras acts downstream of NO and that NO activates Ras by nitrosylation. (b) U0126, a specific MEK inhibitor, completely abolished BNIP3 expression and the stimulation of promoter activity by NO and Ras, whereas 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, SB203580, and wortmannin, specific inhibitors of soluble guanylyl cyclase, p38 MAPK, and phosphatidylinositol 3-kinase, respectively, had no effect. Ras, MEK1/2, and ERK1/2 were sequentially activated by NO treatment of macrophages. (c) Mutation of the HIF-1-binding site (hypoxia-response element) in the Bnip3 promoter abolished BNIP3 induction, and HIF-1alpha was strongly induced by NO. (d) Transient expression of activated Ras promoted macrophage death, as did NO, and this Ras-mediated cell death was inhibited by silencing BNIP3 expression. These results suggest that NO-induced death of macrophages is mediated, at least in part, by BNIP3 induction.

    The Journal of biological chemistry 2006;281;45;33939-48

  • Inhibitory effect of peroxiredoxin II (Prx II) on Ras-ERK-NFkappaB pathway in mouse embryonic fibroblast (MEF) senescence.

    Han YH, Kwon JH, Yu DY and Moon EY

    Department of Human Genomics, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Taejeon, 305-806, South Korea.

    Intracellular reactive oxygen species (ROS) were attenuated by the expression of peroxiredoxin II (Prx II). Cellular senescence as judged by senescence-associated (SA)-beta-galactosidase (Gal) positive cell formation was increased in Prx II-deficient mouse embryonic fibroblast (MEF). Ras expression was increased following passages. The level of Ras expression was higher in Prx II-/- MEF than wild type MEF. ERK activity was also augmented by the deletion of Prx II. SA-beta-Gal-positive cell formation was reduced by PD98059, ERK inhibitor. Activated nuclear transcription factor, nuclear factor-kappaB (NFkappaB) by the deletion of Prx II was inhibited by the treatment with PD98059. In contrast, no changes in SA-beta-Gal-positive cell formation were detected by NFkappaB inhibitor, N-alpha-tosyl-L-phenylalanyl chloromethyl ketone (TPCK). Collectively, results suggest that Prx II deletion activate Ras-ERK-NFkappaB pathways and cellular senescence in Prx II-/- MEF cells was mediated by ERK activation but not by NFkappaB activation.

    Free radical research 2006;40;11;1182-9

  • Ras signaling is essential for lens cell proliferation and lens growth during development.

    Xie L, Overbeek PA and Reneker LW

    Department of Ophthalmology, School of Medicine, University of Missouri, Columbia, MO 65212, USA.

    The vertebrate ocular lens is a simple and continuously growing tissue. Growth factor-mediated receptor tyrosine kinases (RTKs) are believed to be required for lens cell proliferation, differentiation and survival. The signaling pathways downstream of the RTKs remain to be elucidated. Here, we demonstrate the important role of Ras in lens development by expressing a dominant-negative form of Ras (dn-Ras) in the lens of transgenic mice. We show that lens in the transgenic mice was smaller and lens growth was severely inhibited as compared to the wild-type lens. However, the lens shape, polarity and transparency appeared normal in the transgenic mice. Further analysis showed that cell proliferation is inhibited in the dn-Ras lens. For example, the percentage of 5-bromo-2'-deoxyuridine (BrdU)-labeled cells in epithelial layer was about 2- to 3-fold lower in the transgenic lens than in the wild-type lens, implying that Ras activity is required for normal cell proliferation during lens development. We also found a small number of apoptotic cells in both epithelial and fiber compartment of the transgenic lens, suggesting that Ras also plays a role in cell survival. Interestingly, although there was a delay in primary fiber cell differentiation, secondary fiber cell differentiation was not significantly affected in the transgenic mice. For example, the expression of beta- and gamma-crystallins, the marker proteins for fiber differentiation, was not changed in the transgenic mice. Biochemical analysis indicated that ERK activity, but not Akt activity, was significantly reduced in the dn-Ras transgenic lenses. Overall, our data imply that the RTK-Ras-ERK signaling pathway is essential for cell proliferation and, to a lesser extent, for cell survival, but not for crystallin gene expression during fiber differentiation. Thus, some of the fiber differentiation processes are likely mediated by RTK-dependent but Ras-independent pathways.

    Funded by: NEI NIH HHS: EY10448, EY13146, EY14795

    Developmental biology 2006;298;2;403-14

  • Regulation of p21/ras protein expression by diallyl sulfide in DMBA induced neoplastic changes in mouse skin.

    Arora A, Kalra N and Shukla Y

    Environmental Carcinogenesis Division, Industrial Toxicology Research Centre, P.O. Box 80, M.G. Marg, Lucknow 226001, India.

    Diallyl sulfide (DAS), a naturally occurring organosulfide, present in garlic, is known to possess pleiotropic biological effects. DAS is known to inhibit chemically induced tumors in a number of animal models. The chemopreventive properties of DAS seem to occur through a number of mechanisms, but its role on primary events on oncogenic activation is not well understood. In the present study, we demonstrated the modulatory effect of DAS on the expression of H-ras gene product, p21/ras protein as one of the mechanisms of its chemopreventive action in chemically induced mouse skin tumors. Our results showed that DAS administration leads to modulation of the DMBA-induced levels of p21/ras oncoprotein as early as 24h after the DMBA application, suggesting down-regulation of the p21/ras by DAS. Furthermore, the modulatory effects of DAS were also evident in DMBA-induced mouse skin tumors. DAS administration led to increase in the levels of cytosolic p21/ras and decrease in the levels of p21/ras in membrane fractions. DAS administration was also found to down regulate the DMBA-induced H-ras mRNA level in mouse skin tumors. The immunohistochemical staining of the skin/tumor showed 55.82 and 46.86% decrease in the area positive for p21/ras expression levels in DAS pre- and post-supplemented groups, respectively. Flow-cytometric analysis, further confirms our results as indicated by a shift in the mean fluorescence intensity (MFI) towards lower fluorescence in DAS administered groups in comparison to the DMBA treated group. Thus, one mechanism of the growth inhibitory properties of DAS is through the suppression of development of tumors that harbor ras mutations by inhibiting the membrane association of oncogenic p21/ras protein.

    Cancer letters 2006;242;1;28-36

  • Characterization of R-ras3/m-ras null mice reveals a potential role in trophic factor signaling.

    Nuñez Rodriguez N, Lee IN, Banno A, Qiao HF, Qiao RF, Yao Z, Hoang T, Kimmelman AC and Chan AM

    Department of Oncological Sciences, The Mount Sinai School of Medicine, New York, New York 10029, USA.

    R-Ras3/M-Ras is a member of the RAS superfamily of small-molecular-weight GTP-binding proteins. Previous studies have demonstrated high levels of expression in several regions of the central nervous system, and a constitutively active form of M-Ras promotes cytoskeletal reorganization, cellular transformation, survival, and differentiation. However, the physiological functions of M-Ras during embryogenesis and postnatal development have not been elucidated. By using a specific M-Ras antibody, we demonstrated a high level of M-Ras expression in astrocytes, in addition to neurons. Endogenous M-Ras was activated by several trophic factors in astrocytes, including epidermal growth factor (EGF), basic fibroblast growth factor, and hepatocyte growth factor. Interestingly, M-Ras activation by EGF was more sustained compared to prototypic Ras. A mouse strain deficient in M-Ras was generated to investigate its role in development. M-Ras null mice appeared phenotypically normal, and there was a lack of detectable morphological and neurological defects. In addition, primary astrocytes derived from Mras(-/-) mice did not appear to display substantial alterations in the activation of both the mitogen-activated protein kinase and phosphatidylinositol 3-kinase pathways in response to trophic factors.

    Funded by: NCI NIH HHS: CA78509, CA88302, R24 CA088302; NIMH NIH HHS: MH59771, R01 MH059771

    Molecular and cellular biology 2006;26;19;7145-54

  • Rheb inhibits C-raf activity and B-raf/C-raf heterodimerization.

    Karbowniczek M, Robertson GP and Henske EP

    Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.

    The Ras-Raf-MEK signaling cascade is critical for normal development and is activated in many forms of cancer. We have recently shown that B-Raf kinase interacts with and is inhibited by Rheb, the target of the GTPase-activating domain of the tuberous sclerosis complex 2 gene product tuberin. Here, we demonstrate for the first time that activation of Rheb is associated with decreased B-Raf and C-Raf phosphorylation at residues Ser-446 and Ser-338, respectively, concomitant with a decrease in the activities of both kinases and decreased heterodimerization of B-Raf and C-Raf. Importantly, the impact of Rheb on B-Raf/C-Raf heterodimerization and kinase activity are rapamycin-insensitive, indicating that they are independent of Rheb activation of the mammalian target of rapamycin-Raptor complex. In addition, we found that Rheb inhibits the association of B-Raf with H-Ras. Taken together, these results support a central role of Rheb in the regulation of the Ras/B-Raf/C-Raf/MEK signaling network.

    Funded by: NIDDK NIH HHS: DK 51052

    The Journal of biological chemistry 2006;281;35;25447-56

  • Zonal gene expression in murine liver: Are tumors helping us to solve the mystery?

    Gebhardt R and Ueberham E

    Hepatology (Baltimore, Md.) 2006;44;2;512; author reply 512-3

  • G1/S arrest induced by histone deacetylase inhibitor sodium butyrate in E1A + Ras-transformed cells is mediated through down-regulation of E2F activity and stabilization of beta-catenin.

    Abramova MV, Pospelova TV, Nikulenkov FP, Hollander CM, Fornace AJ and Pospelov VA

    Institute of Cytology, Russian Academy of Sciences, St. Petersburg.

    Tumor cells are often characterized by a high and growth factor-independent proliferation rate. We have previously shown that REF cells transformed with oncogenes E1A and c-Ha-Ras do not undergo G(1)/S arrest of the cell cycle after treatment with genotoxic factors. In this work, we used sodium butyrate, a histone deacetylase inhibitor, to show that E1A + Ras transformants were able to stop proliferation and undergo G(1)/S arrest. Apart from inducing G(1)/S arrest, sodium butyrate was shown to change expression of a number of cell cycle regulatory genes. It down-regulated cyclins D1, E, and A as well as c-myc and cdc25A and up-regulated the cyclin-kinase inhibitor p21(waf1). Accordingly, activities of cyclin E-Cdk2 and cyclin A-Cdk2 complexes in sodium butyrate-treated cells were decreased substantially. Strikingly, E2F1 expression was also down-modulated at the levels of gene transcription, the protein content, and the E2F transactivating capability. To further study the role of p21(waf1) in the sodium butyrate-induced G(1)/S arrest and the E2F1 down-modulation, we established E1A + Ras transformants from mouse embryo fibroblast cells with deletion of the cdkn1a (p21(waf1)) gene. Despite the absence of p21(waf1), sodium butyrate-treated mERas transformants reveal a slightly delayed G(1)/S arrest as well as down-modulation of E2F1 activity, implying that the observed effects are mediated through an alternative p21(waf1)-independent signaling pathway. Subsequent analysis showed that sodium butyrate induced accumulation of beta-catenin, a downstream component of the Wnt signaling. The results obtained indicate that the antiproliferative effect of histone deacetylase inhibitors on E1A + Ras-transformed cells can be mediated, alongside other mechanisms, through down-regulation of E2F activity and stabilization of beta-catenin.

    Funded by: PHS HHS: G-3-00-336

    The Journal of biological chemistry 2006;281;30;21040-51

  • Involvement of H- and N-Ras isoforms in transforming growth factor-beta1-induced proliferation and in collagen and fibronectin synthesis.

    Martínez-Salgado C, Fuentes-Calvo I, García-Cenador B, Santos E and López-Novoa JM

    Unidad de Investigación, Hospital Universitario de Salamanca, Salamanca, Spain. carloms@usal.es

    Transforming growth factor beta1 (TGF-beta1) has a relevant role in the origin and maintenance of glomerulosclerosis and tubule-interstitial fibrosis. TGF-beta and Ras signaling pathways are closely related: TGF-beta1 overcomes Ras mitogenic effects and Ras counteracts TGF-beta signaling. Tubule-interstitial fibrosis is associated to increases in Ras, Erk, and Akt activation in a renal fibrosis model. We study the role of N- and H-Ras isoforms, and the involvement of the Ras effectors Erk and Akt, in TGF-beta1-mediated extracellular matrix (ECM) synthesis and proliferation, using embrionary fibroblasts from double knockout (KO) mice for H- and N-Ras (H-ras(-/-)/N-ras(-/-)) isoforms and from heterozygote mice (H-ras(+/-)/N-ras(+/-)). ECM synthesis is increased in basal conditions in H-ras(-/-)/N-ras(-/-) fibroblasts, this increase being higher after stimulation with TGF-beta1. TGF-beta1-induced fibroblast proliferation is smaller in H-ras(-/-)/N-ras(-/-) than in H-ras(+/-)/N-ras(+/-) fibroblasts. Erk activation is decreased in H-ras(-/-)/N-ras(-/-) fibroblasts; inhibition of Erk activation reduces fibroblast proliferation. Akt activation is higher in double KO fibroblasts than in heterozygotes; inhibition of Akt activation also inhibits ECM synthesis. We suggest that H- and N-Ras isoforms downregulate ECM synthesis, and mediate proliferation, in part through MEK/Erk activation. PI3K-Akt pathway activation may be involved in the increase in ECM synthesis observed in the absence of H- and N-Ras.

    Experimental cell research 2006;312;11;2093-106

  • Activation of the lutropin/choriogonadotropin receptor in MA-10 cells stimulates tyrosine kinase cascades that activate ras and the extracellular signal regulated kinases (ERK1/2).

    Shiraishi K and Ascoli M

    Department of Pharmacology, 2-319B BSB, 51 Newton Road, The University of Iowa, Iowa City, 52242-1109, USA.

    We show that activation of the recombinant lutropin/choriogonadotropin receptor (LHR) in mouse Leydig tumor cells (MA-10 cells) leads to the tyrosine phosphorylation of Shc (Src homology and collagen homology) and the formation of complexes containing Shc and Sos (Son of sevenless), a guanine nucleotide exchange factor for Ras. Because a dominant-negative mutant of Shc inhibits the LHR-mediated activation of Ras and the phosphorylation of ERK1/2, we conclude that the LHR-mediated phosphorylation of ERK1/2 is mediated, at least partially, by the classical pathway used by growth factor receptors. We also show that the endogenous epidermal growth factor receptor (EGFR) present in MA-10 cells is phosphorylated upon activation of the LHR. The LHR-mediated phosphorylation of the EGFR and Shc, the activation of Ras, and the phosphorylation of ERK1/2 are inhibited by expression of a dominant-negative mutant of Fyn, a member of the Src family kinases (SFKs) expressed in MA-10 cells and by PP2, a pharmacological inhibitor of the SFKs. These are also inhibited, but to a lesser extent, by AG1478, an inhibitor of the EGFR kinase. We conclude that the SFKs are responsible for the LHR-mediated phosphorylation of the EGFR and Shc, the formation of complexes containing Shc and Sos, the activation of Ras, and the phosphorylation of ERK1/2.

    Funded by: NCI NIH HHS: CA-40629, R01 CA040629

    Endocrinology 2006;147;7;3419-27

  • Neurofibromin is a novel regulator of RAS-induced signals in primary vascular smooth muscle cells.

    Li F, Munchhof AM, White HA, Mead LE, Krier TR, Fenoglio A, Chen S, Wu X, Cai S, Yang FC and Ingram DA

    Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut Street, Indianapolis, IN 46202, USA.

    Neurofibromatosis type I (NF1) is a genetic disorder caused by mutations in the NF1 tumor suppressor gene. Neurofibromin is encoded by NF1 and functions as a negative regulator of Ras activity. NF1 patients develop renal artery stenosis and arterial occlusions resulting in cerebral and visceral infarcts. Further, NF1 patients develop vascular neurofibromas where tumor vessels are invested in a dense pericyte sheath. Although it is well established that aberrations in Ras signaling lead to human malignancies, emerging data generated in genetically engineered mouse models now implicate perturbations in the Ras signaling axis in vascular smooth muscular cells (VSMCs) as central to the initiation and progression of neointimal hyperplasia and arterial stenosis. Despite these observations, the function of neurofibromin in regulating VSMC function and how Ras signals are terminated in VSMCs is virtually unknown. Utilizing VSMCs harvested from Nf1+/- mice and primary human neurofibromin-deficient VSMCs, we identify a discrete Ras effector pathway, which is tightly regulated by neurofibromin to limit VSMC proliferation and migration. Thus, these studies identify neurofibromin as a novel regulator of Ras activity in VSMCs and provide a framework for understanding cardiovascular disease in NF1 patients and a mechanism by which Ras signals are attenuated for maintaining VSMC homeostasis in blood vessel walls.

    Funded by: NCI NIH HHS: 1K08 CA 096579-01, P30 CA 82709; NINDS NIH HHS: P50 NS 052606

    Human molecular genetics 2006;15;11;1921-30

  • Oncogenic Ras inhibits anoikis of intestinal epithelial cells by preventing the release of a mitochondrial pro-apoptotic protein Omi/HtrA2 into the cytoplasm.

    Liu Z, Li H, Derouet M, Berezkin A, Sasazuki T, Shirasawa S and Rosen K

    Departments of Pediatrics & Biochemistry and Molecular Biology, Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.

    Resistance of cancer cells to anoikis, apoptosis induced by cell detachment from the extracellular matrix, is thought to represent a critical feature of the malignant phenotype. Mechanisms that control anoikis of normal and cancer cells are understood only in part. Previously we found that anoikis of non-malignant intestinal epithelial cells is driven by detachment-induced down-regulation of Bcl-X(L), a protein that blocks apoptosis through preventing the release of death-promoting factors from the mitochondria. Mitochondrial proteins the release of which causes anoikis are presently unknown. Similar to what was previously observed by others for keratinocytes and fibroblasts, we show here that anoikis of intestinal epithelial cells does not involve caspase-9, a target of a mitochondrial protein cytochrome c. Furthermore, Smac/Diablo, another mitochondrial pro-apoptotic factor, does not appear to play a role in detachment-dependent apoptosis of these cells either. Instead, anoikis of intestinal epithelial cells is triggered by the release of a mitochondrial protein Omi/HtrA2, an event driven by detachment-induced down-regulation of Bcl-X(L). Moreover, we established that oncogenic ras inhibits anoikis by preventing the release of Omi/HtrA2. This effect of ras required ras-induced down-regulation of a pro-apoptotic protein Bak and could be blocked by an inhibitor of phosphoinositide 3-kinase, a target of Ras that was previously implicated by us in the down-regulation of Bak and blockade of anoikis. We conclude that Omi/HtrA2 is an inducer of anoikis and an important regulator of ras-induced transformation.

    The Journal of biological chemistry 2006;281;21;14738-47

  • Activating transcription factor 3, a stress-inducible gene, suppresses Ras-stimulated tumorigenesis.

    Lu D, Wolfgang CD and Hai T

    Ohio State Biochemistry Program, Department of Molecular and Cellular Biochemistry and Center for Molecular Neurobiology, Ohio State University, Columbus, OH 43210, USA.

    ATF3 is a stress-inducible gene that encodes a member of the ATF/CREB family of transcription factors. Current literature indicates that ATF3 affects cell death and cell cycle progression. However, controversies exist, because it has been demonstrated to be a negative or positive regulator of these processes. We sought to study the roles of ATF3 in both cell death and cell cycle regulation in the same cell type using mouse fibroblasts. We show that ATF3 promotes apoptosis and cell cycle arrest. Fibroblasts deficient in ATF3 (ATF3(-/-)) were partially protected from UV-induced apoptosis, and fibroblasts ectopically expressing ATF3(-/-) under the tet-off system exhibited features characteristic of apoptosis upon ATF3 induction. Furthermore, ATF3(-/-) fibroblasts transitioned from G(2) to S phase more efficiently than the ATF3(+/+) fibroblasts, suggesting a growth arrest role of ATF3. Consistent with the growth arrest and pro-apoptotic roles of ATF3, ATF3(-) fibroblasts upon Ras transformation exhibited higher growth rate, produced more colonies in soft agar, and formed larger tumor upon xenograft injection than the ATF3(+/+) counterparts. ATF3(-/-) cells, either with or without Ras transformation, had increased Rb phosphorylation and higher levels of various cyclins. Significantly, ATF3 bound to the cyclin D1 promoter as shown by chromatin immunoprecipitation (ChIP) assay and repressed its transcription by a transcription assay. Taken together, our results indicate that ATF3 promotes cell death and cell arrest, and suppresses Ras-mediated tumorigenesis. Potential explanations for the controversy about the roles of ATF3 in cell cycle and cell death are discussed.

    Funded by: NCI NIH HHS: R01 CA118306; NIDDK NIH HHS: DK 59605

    The Journal of biological chemistry 2006;281;15;10473-81

  • H-Ras, R-Ras, and TC21 differentially regulate ureteric bud cell branching morphogenesis.

    Pozzi A, Coffa S, Bulus N, Zhu W, Chen D, Chen X, Mernaugh G, Su Y, Cai S, Singh A, Brissova M and Zent R

    Department of Research Medicine, Veterans Affairs Hospital, Nashville, TN 37232, USA.

    The collecting system of the kidney, derived from the ureteric bud (UB), undergoes repetitive bifid branching events during early development followed by a phase of tubular growth and elongation. Although members of the Ras GTPase family control cell growth, differentiation, proliferation, and migration, their role in development of the collecting system of the kidney is unexplored. In this study, we demonstrate that members of the R-Ras family of proteins, R-Ras and TC21, are expressed in the murine collecting system at E13.5, whereas H-Ras is only detected at day E17.5. Using murine UB cells expressing activated H-Ras, R-Ras, and TC21, we demonstrate that R-Ras-expressing cells show increased branching morphogenesis and cell growth, TC21-expressing cells branch excessively but lose their ability to migrate, whereas H-Ras-expressing cells migrated the most and formed long unbranched tubules. These differences in branching morphogenesis are mediated by differential regulation/activation of the Rho family of GTPases and mitogen-activated protein kinases. Because most branching of the UB occurs early in development, it is conceivable that R-Ras and TC-21 play a role in facilitating branching and growth in early UB development, whereas H-Ras might favor cell migration and elongation of tubules, events that occur later in development.

    Funded by: NCI NIH HHS: R01 CA 94849, R01 CA094849; NIDDK NIH HHS: R01 DK 074359, R01 DK 69921, R01 DK069921, R01 DK074359

    Molecular biology of the cell 2006;17;4;2046-56

  • APC inhibits ERK pathway activation and cellular proliferation induced by RAS.

    Park KS, Jeon SH, Kim SE, Bahk YY, Holmen SL, Williams BO, Chung KC, Surh YJ and Choi KY

    Division of Molecular and Cellular Biology, Department of Biotechnology, Yonsei University, Seoul 120-752, Korea.

    Inactivating mutations in the adenomatous polyposis coli gene (APC), and activating mutations in RAS, occur in a majority of colorectal carcinomas. However, the relationship between these changes and tumorigenesis is poorly understood. RAS-induced activation of the ERK pathway was reduced by overexpressing APC in DLD-1 colorectal cancer cells. ERK activity was increased by Cre-virus-induced Apc knockout in primary Apc(flox/flox) mouse embryonic fibroblasts, indicating that APC inhibits ERK activity. ERK activity was increased by overexpression and decreased by knock down of beta-catenin. The activation of Raf1, MEK and ERK kinases by beta-catenin was reduced by co-expression of APC. These results indicate that APC inhibits the ERK pathway by an action on beta-catenin. RAS-induced activation of the ERK pathway was reduced by the dominant negative form of TCF4, indicating that the ERK pathway regulation by APC/beta-catenin signaling is, at least, partly caused by effects on beta-catenin/TCF4-mediated gene expression. The GTP loading and the protein level of mutated RAS were decreased in cells with reduced ERK activity as a result of APC overexpression, indicating that APC regulates RAS-induced ERK activation at least partly by reduction of the RAS protein level. APC regulates cellular proliferation and transformation induced by activation of both RAS and beta-catenin signaling.

    Journal of cell science 2006;119;Pt 5;819-27

  • Constitutive activation of ras in neurons: implications for the regulation of the mammalian circadian clock.

    Serchov T and Heumann R

    Department of Molecular Neurobiochemistry and IGSN, Ruhr-University, Bochum, Germany.

    Almost all organisms living on earth exhibit rhythms under the control of autonomous timekeeping mechanisms referred to as circadian clocks. In mammals, peripheral clocks are synchronized (entrained) with high precision in a 24 h periodicity by the master circadian clock located in the suprachiasmatic nucleus (SCN) of the ventral hypothalamus. Light is the strongest phase-adjusting stimulus of the circadian clock. Circadian oscillations are driven by transcription/translation-based feedback/feedforward loops, comprising a set of clock genes and their protein products. The signalling pathways that couple light input to transcriptional, translational, and post-translational changes to ensure precise entrainment of the clock are not yet well characterized. A candidate pathway for transmission of photic information in the SCN is represented by the extracellular signal-regulated kinases ERK1/ERK2. In neurons, the ERK pathway is activated by a large array of stimuli, including trophic factors, neurotransmitters, and modulatory peptides. An upstream element of the ERK signalling route is the small intracellular membrane-anchored G-protein, Ras. In order to study its possible role in the entrainment of the circadian clock we are using transgenic gain-of-function mice expressing constitutively activated Val-12 Ha-Ras selectively in neurons (synRas mice). The Ha-Ras transgene protein is expressed in the SCN of synRas mice neurons serving as a model for interfering with the normal rhythmic changes in Ras activities in the SCN. This will allow us to investigate whether the associated modulation of the downstream targets such as ERK activities will interfere with the mechanisms of entrainment.

    Chronobiology international 2006;23;1-2;191-200

  • Math1 target genes are enriched with evolutionarily conserved clustered E-box binding sites.

    Krizhanovsky V, Soreq L, Kliminski V and Ben-Arie N

    Department of Cell and Animal Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.

    The basic helix-loop-helix (bHLH) transcription factor Math1 and its orthologs are fundamental for proper development of various neuronal subpopulations, such as cerebellar granule cells, D1 interneurons in the spinal cord, and inner ear hair cells. Although crucial for neurogenesis, the mechanisms by which Math1 specifically recognizes its direct targets are not fully understood. To search for direct and indirect target genes and signaling pathways controlled by Math1, we analyzed the effect of Math1 knockout on the expression profile of multiple genes in the embryonic cerebellum. Eighteen differentially expressed transcripts were identified and found to belong to a few developmentally-related functional groups, such as transcriptional regulation, proliferation, organogenesis, signal transduction, and apoptosis. Importantly, genomic analysis of E-box motifs has identified a significant enrichment and clustering of MATH1-binding E-boxes only in a subset of differentially expressed genes (Nr2f6, Hras1, and Hes5) in both mouse and man. Moreover, Math1 was shown by chromatin immunoprecipitation (ChIP) to bind, and by a luciferase reporter assay to activate transcription, of an upstream genomic fragment of Nr2f6. Taken together, we propose that when putative direct targets of Math1 are being selected for detailed studies on DNA microarray hybridization, the enrichment and clustering of binding E-boxes in multiple species may be helpful criteria. Our findings may be useful to the study of other bHLH transcription factors, many of which control the development of the nervous system.

    Journal of molecular neuroscience : MN 2006;28;2;211-29

  • Pure lipopolysaccharide or synthetic lipid A induces activation of p21Ras in primary macrophages through a pathway dependent on Src family kinases and PI3K.

    David MD, Cochrane CL, Duncan SK and Schrader JW

    Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.

    Recognition of bacterial LPS by macrophages plays a critical role in host defense against infection by Gram-negative bacteria. However, when not tightly regulated, the macrophage's response to LPS can induce severe disease and septic shock. Although LPS triggers the activation of multiple signaling pathways in macrophages, it was unclear whether these include activation of the p21Ras GTPases. We report that p21Ras is rapidly and transiently activated in murine primary macrophages stimulated with an ultra-pure preparation of LPS or with synthetic lipid A. The molecular basis of this activation was investigated using a pharmacological approach. LPS-induced activation of p21Ras was inhibited in the presence of PP2, LY294002, or wortmannin, suggesting that it depends on the activity of one or more members of the Src kinase family and the subsequent activation of PI3K. In that pharmacological inhibitors of PI3K inhibited LPS-induced activation of p21Ras, but not activation of ERK, we concluded that LPS-induced activation of ERK occurs through a pathway that is not dependent on the activation of p21Ras.

    Journal of immunology (Baltimore, Md. : 1950) 2005;175;12;8236-41

  • Enhanced erythropoiesis mediated by activation of the renin-angiotensin system via angiotensin II type 1a receptor.

    Kato H, Ishida J, Imagawa S, Saito T, Suzuki N, Matsuoka T, Sugaya T, Tanimoto K, Yokoo T, Ohneda O, Sugiyama F, Yagami K, Fujita T, Yamamoto M, Nangaku M and Fukamizu A

    Center for Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Ibaraki, Japan.

    Although clinical and experimental studies have long suggested a role for the renin-angiotensin system (RAS) in the regulation of erythropoiesis, the molecular basis of this role has not been well understood. We report here that transgenic mice carrying both the human renin and human angiotensinogen genes displayed persistent erythrocytosis as well as hypertension. To identify the receptor molecule responsible for this phenotype, we introduced both transgenes into the AT1a receptor null background and found that the hematocrit level in the compound mice was restored to the normal level. Angiotensin II has been shown to influence erythropoiesis by two means, up-regulation of erythropoietin levels and direct stimulation of erythroid progenitor cells. Thus, we conducted bone marrow transplantation experiments and clarified that AT1a receptors on bone marrow-derived cells were dispensable for RAS-dependent erythrocytosis. Plasma erythropoietin levels and kidney erythropoietin mRNA expression in the double transgenic mice were significantly increased compared with those of the wild-type control, while the elevated plasma erythropoietin levels were significantly attenuated in the compound mice. These results provide clear genetic evidence that activated RAS enhances erythropoiesis through the AT1a receptor of kidney cells and that this effect is mediated by the elevation of plasma erythropoietin levels in vivo.

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology 2005;19;14;2023-5

  • Crosstalk between Pten and Ras signaling pathways in tumor development.

    To MD, Perez-Losada J, Mao JH and Balmain A

    UCSF Comprehensive Cancer Center, San Francisco, California 94115, USA.

    The Pten and Ras pathways are disrupted or activated, respectively, in a substantial proportion of cancers. Skin tumors induced by the classical two stage carcinogenesis protocols show consistent activating mutations of the H-ras gene, but in tumors from Pten heterozygous mice, the frequency of these mutations is markedly decreased, suggesting some redundancy between these pathways. Pten heterozygous mice develop more papillomas and have earlier onset of carcinomas than their control counterparts, but molecular analysis of these tumors indicated that complete loss of Pten and activation of H-ras are mutually exclusive. Pten loss is however not functionally equivalent to H-ras activation, as Pten-/- tumors occur earlier and are generally more aggressive. Tumors with Pten loss or H-ras activation have different biochemical properties, suggestive of alternative routes to malignancy. These findings in this mouse model have important implications for the rational design of new targeted therapies for human tumors.

    Cell cycle (Georgetown, Tex.) 2005;4;9;1185-8

  • Harvey-ras gene expression and epidermal cell proliferation in dibenzo[a,l]pyrene-treated early preneoplastic SENCAR mouse skin.

    Khan GA, Bhattacharya G, Mailander PC, Meza JL, Hansen LA and Chakravarti D

    Eppley Institute for Research in Cancer and Allied Diseases, Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.

    Topical application of dibenzo[a,l]pyrene (DB[a,l]P) to the dorsal skin of SENCAR mice induces codon 61 (CAA Gln to CTA Leu) mutations in the Harvey (H)-ras gene within 12 h after treatment. Between days 1 and 3, the frequency of these mutations increases rapidly, suggesting that skin cells carrying the codon 61 mutations proliferate in this period. We have investigated DB[a,l]P-treated mouse skin (12 h-7 d) for further evidence of H-ras expression and epidermal cell proliferation. Two waves of cell proliferation were observed: the first wave (1-2 d) correlated with the clonal proliferation of codon 61-mutated cells, and the second wave (3-7 d) correlated with DB[a,l]P-induced hyperplasia. DB[a,l]P-induced early preneoplastic cell proliferation correlated with H-ras and specific G1 cyclin expression. Total H-ras protein and cyclin D1 were found to increase during DB[a,l]P-induced hyperplasia, but the levels of guanosine triphosphate-bound (active) H-ras protein and cyclin E were increased during the putative clonal proliferation of codon 61-mutated cells. These results suggest that DB[a,l]P-induced oncogenically mutated cells proliferate in early preneoplastic skin. As this proliferation occurs in the absence of any promoting treatment, we propose that this phenomenon is a tumor initiation event.

    Funded by: NCI NIH HHS: P01CA 49210; NCRR NIH HHS: P20RR17675

    The Journal of investigative dermatology 2005;125;3;567-74

  • Krüppel-like factor 5 promotes mitosis by activating the cyclin B1/Cdc2 complex during oncogenic Ras-mediated transformation.

    Nandan MO, Chanchevalap S, Dalton WB and Yang VW

    Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, 201 Whitehead Research Building, 615 Michael Street, Atlanta, GA 30322, USA.

    We previously showed that the zinc finger-containing transcription factor Krüppel-like factor 5 (KLF5) is important in mediating transformation by oncogenic H-Ras through induction of cyclin D1 expression and acceleration of the G1/S transition of the cell cycle. Here we present evidence of a role for KLF5 in accelerating mitotic entry in H-Ras-transformed NIH3T3 fibroblasts. When compared with non-transformed parental NIH3T3 cells, H-Ras-transformed fibroblasts exhibit an increase in mitotic index, levels of cyclin B1 and Cdc2, and cyclin B1/Cdc2 kinase activity. Inhibition of KLF5 expression in H-Ras-transformed cells with KLF5-specific small interfering RNA (siRNA) results in a decrease in each of the aforementioned parameters, with a concomitant reduction in the transforming potential of the cells. Conversely, over-expression of KLF5 in NIH3T3 cells leads to an increase in the promoter activity of the genes encoding cyclin B1 and Cdc2. These results indicate that KLF5 accelerates mitotic entry in H-Ras-transformed cells by transcriptionally activating cyclin B1 and Cdc2, which leads to an increase in cyclin B1/Cdc2 kinase activity. Extending our previous observation that KLF5 activates cyclin D1 transcription to promote G1/S transition, our current results further support a crucial function for KLF5 in mediating cellular transformation caused by oncogenic H-Ras.

    Funded by: NCI NIH HHS: CA84197, R01 CA084197-08; NIDDK NIH HHS: DK52230, DK64399, R01 DK052230-09, R24 DK064399-03

    FEBS letters 2005;579;21;4757-62

  • Combined subcarcinogenic benzo[a]pyrene and UVA synergistically caused high tumor incidence and mutations in H-ras gene, but not p53, in SKH-1 hairless mouse skin.

    Wang Y, Gao D, Atencio DP, Perez E, Saladi R, Moore J, Guevara D, Rosenstein BS, Lebwohl M and Wei H

    Department of Dermatology, Mount Sinai School of Medicine, New York, NY 10029, USA.

    Combined subcarcinogenic doses of benzo[a]pyrene (BaP) and UVA induced H-ras, but not p53, gene mutations 8 weeks before tumor emergence in SKH-1 mice. Neither UVA (40 kJ/m2) nor BaP (8 nmol) induced any tumors after mice were topically treated 3 times/week for 25 weeks. However, combined BaP-UVA treatment synergistically increased tumor incidence and multiplicity. All tumors induced by BaP-UVA were malignant. The epidermis was collected from mice treated for 2, 6 and 10 weeks. DNA from UVB- (0.3 kJ/m2) or BaP-UVA-(8 nmol and 40 kJ/m2-induced tumors was isolated and screened for H-ras and p53 mutations. Four types of point mutation, GGC-->GAC, GCC, GTC and CGC, occurred in UVB-induced tumors at H-ras codon 13; and one type of point mutation, GGA-->GAA, at codon 12. Treatment with either BaP alone or BaP-UVA for 10 weeks caused GGA-->GAA mutation at codon 12 or GGC-->GAC mutation at codon 13 in nontumor skin, respectively, as well as in tumors induced by BaP-UVA. All of the 10-week samples treated with either BaP or BaP-UVA showed detectable mutations at codons 12 and 13, but the genetic load was significantly higher in BaP-UVA-treated mice than in those exposed only to BaP. UVA alone induced mutations at codon 12 in only one-third of samples. G-->A mutations induced by BaP or BaP-UVA at position 38 of codon 13 have not been reported previously. C-->T transitions were detected in p53 hot spots of exon 8 in 2 of 19 BaP-UVA-induced tumors but were not found in nontumor skin.

    Funded by: NIEHS NIH HHS: R01ES09894

    International journal of cancer. Journal international du cancer 2005;116;2;193-9

  • Cdc42 and Ras cooperate to mediate cellular transformation by intersectin-L.

    Wang JB, Wu WJ and Cerione RA

    Department of Molecular Medicine, Veterinary Medical Center, Cornell University, Ithaca, New York 14853, USA.

    Cdc42, a Ras-related GTP-binding protein, has been implicated in the regulation of the actin cytoskeleton, membrane trafficking, cell-cycle progression, and malignant transformation. We have shown previously that a Cdc42 mutant (Cdc42(F28L)), capable of spontaneously exchanging GDP for GTP (referred to as "fast-cycling"), transformed NIH 3T3 cells because of its ability to interfere with epidermal growth factor receptor (EGFR)-Cbl interactions and EGFR down-regulation. To further examine the link between the hyperactivation of Cdc42 and its ability to alter EGFR signaling and thereby cause cellular transformation, we examined the effects of expressing different forms of the Cdc42-specific guanine nucleotide exchange factor, intersectin-L, in fibroblasts. Full-length intersectin-L exhibited little ability to stimulate nucleotide exchange on Cdc42, whereas a truncated version that contained five Src homology 3 (SH3) domains, the Dbl and pleckstrin homology domains (DH and PH domains, respectively), and a C2 domain (designated as SH3A-C2) showed modest guanine nucleotide exchange factor activity, whereas a form containing just the DH, PH, and C2 domains (DH-C2) strongly activated Cdc42. However, DH-C2 showed little ability to stimulate growth in low serum or colony formation in soft agar, whereas SH3A-C2 gave rise to a much stronger stimulation of cell growth in low serum and was highly effective in stimulating colony formation. Moreover, although SH3A-C2 strongly transformed fibroblasts, it differed from the actions of the Cdc42(F28L) mutant, as SH3A-C2 showed little ability to alter EGFR levels or the lifetime of EGF-coupled signaling through ERK. Rather, we found that SH3A-C2 exhibited strong transforming activity through its ability to mediate cooperation between Ras and Cdc42.

    Funded by: NIGMS NIH HHS: GM47458

    The Journal of biological chemistry 2005;280;24;22883-91

  • Ras-mediated loss of the pro-apoptotic response protein Par-4 is mediated by DNA hypermethylation through Raf-independent and Raf-dependent signaling cascades in epithelial cells.

    Pruitt K, Ulkü AS, Frantz K, Rojas RJ, Muniz-Medina VM, Rangnekar VM, Der CJ and Shields JM

    Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, 27599-7295, USA.

    The apoptosis-promoting protein Par-4 has been shown to be down-regulated in Ras-transformed NIH 3T3 fibroblasts through the Raf/MEK/ERK MAPK pathway. Because mutations of the ras gene are most often found in tumors of epithelial origin, we explored the signaling pathways utilized by oncogenic Ras to down-regulate Par-4 in RIE-1 and rat ovarian surface epithelial (ROSE) cells. We determined that constitutive activation of the Raf, phosphatidylinositol 3-kinase, or Ral guanine nucleotide exchange factor effector pathway alone was not sufficient to down-regulate Par-4 in RIE-1 or ROSE cells. However, treatment of Ras-transformed RIE-1 or ROSE cells with the MEK inhibitors U0126 and PD98059 increased Par-4 protein expression. Thus, although oncogenic Ras utilizes the Raf/MEK/ERK pathway to down-regulate Par-4 in both fibroblasts and epithelial cells, Ras activation of an additional signaling pathway(s) is required to achieve the same outcome in epithelial cells. Methylation-specific PCR showed that the par-4 promoter is methylated in Ras-transformed cells through a MEK-dependent pathway and that treatment with the DNA methyltransferase inhibitor azadeoxycytidine restored Par-4 mRNA transcript and protein levels, suggesting that the mechanism for Ras-mediated down-regulation of Par-4 is by promoter methylation. Support for this possibility is provided by our observation that Ras transformation was associated with up-regulation of Dnmt1 and Dnmt3 DNA methyltransferase expression. Finally, ectopic Par-4 expression significantly reduced Ras-mediated growth in soft agar, but not morphological transformation, highlighting the importance of Par-4 down-regulation in specific aspects of Ras-mediated transformation of epithelial cells.

    Funded by: NCI NIH HHS: CA63071, CA84511

    The Journal of biological chemistry 2005;280;24;23363-70

  • Single-molecule diffusion measurements of H-Ras at the plasma membrane of live cells reveal microdomain localization upon activation.

    Lommerse PH, Snaar-Jagalska BE, Spaink HP and Schmidt T

    Department of Biophysics, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.

    Recent studies show that the partitioning of the small GTPase H-Ras in different types of membrane microdomains is dependent on guanosine 5'-triphosphate (GTP)-loading of H-Ras. Detailed knowledge about the in vivo dynamics of this phenomenon is limited. In this report, the effect of the activation of H-Ras on its microdomain localization was studied by single-molecule fluorescence microscopy. Individual human H-Ras molecules fused to the enhanced yellow fluorescent protein (eYFP) were imaged in the dorsal plasma membrane of live mouse cells and their diffusion behavior was analyzed. The diffusion of a constitutively inactive (S17N) and constitutively active (G12V) mutant of H-Ras was compared. Detailed analysis revealed that for both mutants a major, fast-diffusing population and a minor, slow-diffusing population were present. The slow-diffusing fraction of the active mutant was confined to 200 nm domains, which were not observed for the inactive mutant. In line with these results we observed that the slow-diffusing fraction of wild-type H-Ras became confined to 200 nm domains upon insulin-induced activation of wild-type H-Ras. This activation-dependent localization of H-Ras to 200 nm domains, for the first time directly detected in live cells, supports the proposed relationship between H-Ras microdomain localization and activation.

    Journal of cell science 2005;118;Pt 9;1799-809

  • Role of epidermal growth factor receptor signaling in RAS-driven melanoma.

    Bardeesy N, Kim M, Xu J, Kim RS, Shen Q, Bosenberg MW, Wong WH and Chin L

    Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA. nelbardeesy@partners.org

    The identification of essential genetic elements in pathways governing the maintenance of fully established tumors is critical to the development of effective antioncologic agents. Previous studies revealed an essential role for H-RAS(V12G) in melanoma maintenance in an inducible transgenic model. Here, we sought to define the molecular basis for RAS-dependent tumor maintenance through determination of the H-RAS(V12G)-directed transcriptional program and subsequent functional validation of potential signaling surrogates. The extinction of H-RAS(V12G) expression in established tumors was associated with alterations in the expression of proliferative, antiapoptotic, and angiogenic genes, a profile consistent with the observed phenotype of tumor cell proliferative arrest and death and endothelial cell apoptosis during tumor regression. In particular, these melanomas displayed a prominent RAS-dependent regulation of the epidermal growth factor (EGF) family, leading to establishment of an EGF receptor signaling loop. Genetic complementation and interference studies demonstrated that this signaling loop is essential to H-RAS(V12G)-directed tumorigenesis. Thus, this inducible tumor model system permits the identification and validation of alternative points of therapeutic intervention without neutralization of the primary genetic lesion.

    Funded by: NCI NIH HHS: CA89124, K08 CA089124, P20 CA096470, P20 CA96470, P50 CA093683, P50 CA93683, R01 CA093947, R01 CA93947, U01 CA084313, U01 CA84313

    Molecular and cellular biology 2005;25;10;4176-88

  • Levels of 4-aminobiphenyl-induced somatic H-ras mutation in mouse liver DNA correlate with potential for liver tumor development.

    Parsons BL, Beland FA, Von Tungeln LS, Delongchamp RR, Fu PP and Heflich RH

    Division of Genetic and Reproductive Toxicology, US FDA National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA.

    The utility of liver H-ras codon 61 CAA to AAA mutant fraction as a biomarker of liver tumor development was investigated using neonatal male mice treated with 4-aminobiphenyl (4-ABP). Treatment with 0.1, 0.3, or 1.0 mumol 4-ABP produced dose-dependent increases in liver DNA adducts in B6C3F(1) and C57BL/6N mice. Eight months after treatment with 0.3 mumol 4-ABP or the DMSO vehicle, H-ras codon 61 CAA to AAA mutant fraction was measured in liver DNA samples (n = 12) by allele-specific competitive blocker-polymerase chain reaction (ACB-PCR). A significant increase in average mutant fraction was found in DNA of 4-ABP-treated mice, with an increase from 1.3 x 10(-5) (control) to 44.9 x 10(-5) (treated) in B6C3F(1) mice and from 1.4 x 10(-5) to 7.0 x 10(-5) in C57BL/6N mice. Compared with C57BL/6N mutant fractions, B6C3F(1) mutant fractions were more variable and included some particularly high mutant fractions, consistent with the more rapid development of liver foci expected in B6C3F(1) mouse liver. Twelve months after treatment, liver tumors developed in 79.2% of 4-ABP-treated and 22.2% of control B6C3F(1) mice; thus measurement of H-ras mutant fraction correlated with subsequent tumor development. This study demonstrates that ACB-PCR can directly measure background levels of somatic oncogene mutation and detect a carcinogen-induced increase in such mutation.

    Molecular carcinogenesis 2005;42;4;193-201

  • The p38 SAPK pathway is required for Ha-ras induced in vitro invasion of NIH3T3 cells.

    Behren A, Binder K, Vucelic G, Herberhold S, Hirt B, Loewenheim H, Preyer S, Zenner HP and Simon C

    Department of Otolaryngology, Head and Neck Surgery, The University of Tuebingen, Elfriede-Aulhornstrasse 5, 72076 Tuebingen, Germany.

    Constitutive activation of the ras oncoprotein plays a critical role in cancer invasion and metastasis. Particularly, ras-related protease expression such as the serine protease urokinase plasminogen activator (u-PA) has been implicated in mediating cancer cell invasion. Previous studies have shown that ras-mediated u-PA expression is regulated through the mitogen- (MAPK) and stress-activated protein kinase (SAPK) signal transduction pathways extracellular signal-regulated kinase (ERK) and c-Jun-activating kinase (JNK). We therefore asked the question, if ras-related cell invasion might additionally require the third MAPK/SAPK signal transduction cascade, p38. Indeed, we found that ras induces invasion based on the activation of certain p38 protein kinase isoforms, in particular, p38alpha. Moreover, ras activation through transient or stable expression of a Ha-rasEJ mutant induced the expression of u-PA. This was found to be a consequence of an increase of u-PA m-RNA, which was paralleled by only a modest activation of the u-PA promoter. In conclusion, we provide evidence for the requirement of a novel ras-p38alpha-u-PA pathway for ras-dependent cellular invasion.

    Experimental cell research 2005;303;2;321-30

  • Small Jab1-containing subcomplex is regulated in an anchorage- and cell cycle-dependent manner, which is abrogated by ras transformation.

    Fukumoto A, Tomoda K, Kubota M, Kato JY and Yoneda-Kato N

    First Department of Surgery, Nara Medical University, Nara, Japan.

    Jab1 interacts with a variety of cell cycle and signal transduction regulators to control cell proliferation, differentiation, and tumorigenesis. In this study, we employed a non-denaturing gel electrophoresis method to separate different Jab1-containing complexes, the COP9 signalosome complex and the small Jab1-containing subcomplex. The formation of the small Jab1 complex was dependent on a low cell density and anchorage to a solid support, and enhanced during the early G1 phase of the cell cycle, which was abrogated in ras-transformed cells. The small Jab1-containing subcomplex may be a novel mediator of anchorage and cell-cell contact-dependent signal transduction.

    FEBS letters 2005;579;5;1047-54

  • B-raf and Ha-ras mutations in chemically induced mouse liver tumors.

    Jaworski M, Buchmann A, Bauer P, Riess O and Schwarz M

    1Institut für Pharmakologie und Toxikologie, Abteilung Toxikologie, Universität Tübingen, Wilhelmstr. 56, 72074 Tübingen, Germany.

    The mitogen-activated protein kinase signalling pathway is a central regulator of tumor growth, which is constitutively activated in chemically induced mouse liver tumors. In about 30-50% of cases this effect can be related to activation of the Ha-ras gene by point mutations, whereas in the remaining cases mutations may occur in other members within this pathway, such as Raf kinases. Recently, B-raf has been shown to be frequently mutated in human melanomas and certain other cancers, with a V599E amino-acid change representing the most predominant mutation type. We now screened 82 N-nitrosodiethylamine-induced liver tumors from C3H/He mice for mutations within the hotspot positions in the Ha-ras and B-raf genes. About 50% (39/82) of tumors showed Ha-ras codon 61 mutations and 16 tumors ( approximately 20%) harbored mutations at codon 624 of the B-raf gene, which corresponds to codon 599 in human B-raf. None of the tumors was mutated in both Ha-ras and B-raf. The high prevalence of Ha-ras and B-raf mutations in mouse liver tumors is in striking contrast to human hepatocellular cancers which very infrequently harbor mutations in the two genes. These fundamental differences between the biology of liver tumors in mice and man may be of toxicological relevance.

    Oncogene 2005;24;7;1290-5

  • Ras-Raf-Arf signaling critically depends on the Dmp1 transcription factor.

    Sreeramaneni R, Chaudhry A, McMahon M, Sherr CJ and Inoue K

    Department of Pathology, Wake Forest University Health Sciences, 2102 Gray Building, Medical Center Blvd., Winston-Salem, NC 27157, USA.

    Dmp1 prevents tumor formation by activating the Arf-p53 pathway. In cultured primary cells, the Dmp1 promoter was efficiently activated by oncogenic Ha-Ras(V12), but not by overexpressed c-Myc or E2F-1. Dmp1 promoter activation by Ras(V12) depended on Raf-MEK-ERK signaling. Induction of p19(Arf) and p21(Cip1) by oncogenic Raf was compromised in Dmp1-null cells, which were resistant to Raf-mediated premature senescence. A Ras(V12)-responsive element was mapped to the 5' leader sequence of the murine Dmp1 promoter, where endogenous Fos and Jun family proteins bind. Dmp1 promoter activation by Ras(V12) was strikingly impaired in c-Jun as well as in JunB knock-down cells, suggesting the critical role of Jun proteins in the activation of the Dmp1 promoter. A Ras(V12)-responsive element was mapped to the unique Dmp1/Ets site on the Arf promoter, where endogenous Dmp1 proteins bind upon oncogenic Raf activation. Therefore, activation of Arf by Ras/Raf signaling is indirectly mediated by Dmp1, explaining why Dmp1-null primary cells are highly susceptible to Ras-induced transformation. Our data indicate the presence of the novel Jun-Dmp1 pathway that directly links oncogenic Ras-Raf signaling and p19(Arf), independent of the classical cyclin D1/Cdk4-Rb-E2F pathway.

    Funded by: NCI NIH HHS: CA 106314-01, R01 CA106314

    Molecular and cellular biology 2005;25;1;220-32

  • Analysis of p53 tumor suppressor gene, H-ras protooncogene and proliferating cell nuclear antigen (PCNA) in squamous cell carcinomas of HRA/Skh mice following exposure to 8-methoxypsoralen (8-MOP) and UVA radiation (PUVA therapy).

    Lambertini L, Surin K, Ton TV, Clayton N, Dunnick JK, Kim Y, Hong HH, Devereux TR and Sills RC

    Laboratory of Experimental Pathology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.

    Treatment with 8-methoxypsoralen (8-MOP) and ultraviolet radiation (primarily UVA), called PUVA therapy, has been used to treat different chronic skin diseases but led to a significant increased risk for skin cancer. The National Toxicology Program (NTP) performed a study in mice treated with PUVA that showed a significant increase in squamous cell carcinomas of the skin. In the present study, we evaluated the protein expression of p53 and PCNA and DNA mutations of p53 and H-ras genes in both hyperplastic and neoplastic squamous cell lesions from the NTP study. By immunohistochemical staining, protein expression of both p53 and PCNA was detected in 3/16 (19%) of hyperplastic lesions and 14/17 (82%) of SCCs in groups treated with both 8-MOP and UVA. The mutation frequency of p53 in SCCs from mice administered 8-MOP plus UVA was 15/17 (88%) with a predominant distribution of mutations in exon 6 (14/15 - 93%). No H-ras mutations were detected in the hyperplastic lesions/tumors. The mutagenic effect of PUVA on the p53 tumor suppressor gene may lead to a conformational modification and inactivation of the p53 protein, which are considered critical steps in PUVA-induced skin carcinogenesis. The p53 mutational frequency and patterns from our study were different from those reported in human PUVA-type tumors.

    Toxicologic pathology 2005;33;2;292-9

  • Susceptibilities of p53 knockout and rasH2 transgenic mice to urethane-induced lung carcinogenesis are inherited from their original strains.

    Ozaki M, Ozaki K, Watanabe T, Uwagawa S, Okuno Y and Shirai T

    Department of Experimental Pathology and Tumor Biology, Nagoya City University, Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan. ozakim@sc.sumitomochem.co.jp

    In the present study, susceptibility of CB6F1 mice carrying the human prototype c-Ha-ras gene (rasH2 mice) and p53 gene knockout mice (p53 (+/-) mice) to urethane-induced lung carcinogenesis was compared under the same experimental conditions. Both strains were administered 500 ppm urethane in their drinking water for 3 weeks. At week 26, lung adenocarcinomas and adenomas were observed in 53% and 100% of rasH2 mice, respectively, and lung adenomas were observed in 67% of rasH2 littermate (non-Tg) mice. However, lung tumors were not observed in either p53 (+/-) or p53 (+/+) mice. Peliosis hepatis and hepatic hemangiomas were observed in 27% and 67% of p53 (+/-) mice, but only in 6.7% and 6.7% of the rasH2 animals, respectively. Under the same experimental conditions, BALB/c mice, the strain of origin of the rasH2 mice, developed lung adenomas at an incidence of 93%, whereas none of the C57BL/6 original strain for p53 (+/-) mice developed lung tumors. Peliosis hepatis was observed in 40% of the C57BL/6 mice, but not in BALB/c mice; hepatic and splenic hemangiomas were not observed in these animals. These results indicate that organ susceptibility of rasH2 and p53 (+/-) mice is inherited from their strains of origin, the rasH2 and BALB/c lines being much more sensitive to the induction of pulmonary carcinogenesis.

    Toxicologic pathology 2005;33;2;267-71

  • Identification of PSD-95 palmitoylating enzymes.

    Fukata M, Fukata Y, Adesnik H, Nicoll RA and Bredt DS

    Department of Physiology, University of California at San Francisco, San Francisco, California 94143, USA.

    Palmitoylation is a lipid modification that plays a critical role in protein trafficking and function throughout the nervous system. Palmitoylation of PSD-95 is essential for its regulation of AMPA receptors and synaptic plasticity. The enzymes that mediate palmitoyl acyl transfer to PSD-95 have not yet been identified; however, proteins containing a DHHC cysteine-rich domain mediate palmitoyl acyl transferase activity in yeast. Here, we isolated 23 mammalian DHHC proteins and found that a subset specifically palmitoylated PSD-95 in vitro and in vivo. These PSD-95 palmitoyl transferases (P-PATs) showed substrate specificity, as they did not all enhance palmitoylation of Lck, SNAP-25b, Galpha(s), or H-Ras in cultured cells. Inhibition of P-PAT activity in neurons reduced palmitoylation and synaptic clustering of PSD-95 and diminished AMPA receptor-mediated neurotransmission. This study suggests that P-PATs regulate synaptic function through PSD-95 palmitoylation.

    Neuron 2004;44;6;987-96

  • Functional genetic screen for genes involved in senescence: role of Tid1, a homologue of the Drosophila tumor suppressor l(2)tid, in senescence and cell survival.

    Tarunina M, Alger L, Chu G, Munger K, Gudkov A and Jat PS

    Ludwig Institute for Cancer Research, 91 Riding House St., London W1W 7BS, United Kingdom.

    We performed a genetic suppressor element screen to identify genes whose inhibition bypasses cellular senescence. A normalized library of fragmented cDNAs was used to select for elements that promote immortalization of rat embryo fibroblasts. Fragments isolated by the screen include those with homology to genes that function in intracellular signaling, cellular adhesion and contact, protein degradation, and apoptosis. They include mouse Tid1, a homologue of the Drosophila tumor suppressor gene l(2)tid, recently implicated in modulation of apoptosis as well as gamma interferon and NF-kappaB signaling. We show that GSE-Tid1 enhances immortalization by human papillomavirus E7 and simian virus 40 T antigen and cooperates with activated ras for transformation. Expression of Tid1 is upregulated upon cellular senescence in rat and mouse embryo fibroblasts and premature senescence of REF52 cells triggered by activated ras. In accordance with this, spontaneous immortalization of rat embryo fibroblasts is suppressed upon ectopic expression of Tid1. Modulation of endogenous Tid1 activity by GSE-Tid1 or Tid1-specific RNA interference alleviates the suppression of tumor necrosis factor alpha-induced NF-kappaB activity by Tid1. We also show that NF-kappaB sequence-specific binding is strongly downregulated upon senescence in rat embryo fibroblasts. We therefore propose that Tid1 contributes to senescence by acting as a repressor of NF-kappaB signaling.

    Funded by: NCI NIH HHS: CA 60730, R01 CA060730

    Molecular and cellular biology 2004;24;24;10792-801

  • Libraries enriched for alternatively spliced exons reveal splicing patterns in melanocytes and melanomas.

    Watahiki A, Waki K, Hayatsu N, Shiraki T, Kondo S, Nakamura M, Sasaki D, Arakawa T, Kawai J, Harbers M, Hayashizaki Y and Carninci P

    Genome Science Laboratory, RIKEN, Wako main campus, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan.

    It is becoming increasingly clear that alternative splicing enables the complex development and homeostasis of higher organisms. To gain a better understanding of how splicing contributes to regulatory pathways, we have developed an alternative splicing library approach for the identification of alternatively spliced exons and their flanking regions by alternative splicing sequence enriched tags sequencing. Here, we have applied our approach to mouse melan-c melanocyte and B16-F10Y melanoma cell lines, in which 5,401 genes were found to be alternatively spliced. These genes include those encoding important regulatory factors such as cyclin D2, Ilk, MAPK12, MAPK14, RAB4, melastatin 1 and previously unidentified splicing events for 436 genes. Real-time PCR further identified cell line-specific exons for Tmc6, Abi1, Sorbs1, Ndel1 and Snx16. Thus, the ASL approach proved effective in identifying splicing events, which suggest that alternative splicing is important in melanoma development.

    Nature methods 2004;1;3;233-9

  • Activated H-Ras regulates hematopoietic cell survival by modulating Survivin.

    Fukuda S and Pelus LM

    Department of Microbiology and Immunology, Walther Oncology Center, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, IN 46202, USA.

    Survivin expression and Ras activation are regulated by hematopoietic growth factors. We investigated whether activated Ras could circumvent growth factor-regulated Survivin expression and if a Ras/Survivin axis mediates growth factor independent survival and proliferation in hematopoietic cells. Survivin expression is up-regulated by IL-3 in Ba/F3 and CD34+ cells and inhibited by the Ras inhibitor, farnesylthiosalicylic acid. Over-expression of constitutively activated H-Ras (CA-Ras) in Ba/F3 cells blocked down-modulation of Survivin expression, G0/G1 arrest, and apoptosis induced by IL-3 withdrawal, while dominant-negative (DN) H-Ras down-regulated Survivin. Survivin disruption by DN T34A Survivin blocked CA-Ras-induced IL-3-independent cell survival and proliferation; however, it did not affect CA-Ras-mediated enhancement of S-phase, indicating that the anti-apoptotic activity of CA-Ras is Survivin dependent while its S-phase enhancing effect is not. These results indicate that CA-Ras modulates Survivin expression independent of hematopoietic growth factors and that a CA-Ras/Survivin axis regulates survival and proliferation of transformed hematopoietic cells.

    Funded by: NHLBI NIH HHS: HL079654

    Biochemical and biophysical research communications 2004;323;2;636-44

  • Entire mitogen activated protein kinase (MAPK) pathway is present in preimplantation mouse embryos.

    Wang Y, Wang F, Sun T, Trostinskaia A, Wygle D, Puscheck E and Rappolee DA

    C.S. Mott Center for Human Growth and Development, Department of Obstetrics and Gynecology, Hützel Hospital, Wayne State University School of Medicine, Detroit, Michigan, USA.

    To understand how mitogenic signals are transduced into the trophoblasts in preimplantation embryos, the expression of mitogen-activated protein kinase (MAPK) pathway molecules was tested. We used immunocytochemical means and reverse transcriptase-polymerase chain reaction to test whether MAPK pathway molecule gene products exist at the protein and phosphoprotein level in the zygote and the RNA level in the egg and zygote. In addition, all antibodies detected the correct-sized major band in Westerns of placental cell lines representing the most prevalent cell type in preimplantation embryos. A majority of mRNA transcripts of MAPK pathway genes were detected in unfertilized eggs, and all were expressed in the zygote. We found that the MAPK pathway protein set consisting of the following gene products was present: FRS2 alpha, GRB2, GAB1, SOS1, Ha-ras, Raf1/RafB, MEK1,2,5, MAPK/ERK1,2, MAPK/ERK5, and RSK1,2,3 (see abbreviations). These proteins were detected in trophoblasts in embryonic day (E) 3.5 embryos when they could mediate mitogenic fibroblast growth factor signals from the embryo or colony stimulating factor-1 signals from the uterus. The phosphorylation state and position of the phosphoproteins in the cells suggested that they might function in mediating mitogenic signals. Interestingly, a subtle transition from maternal MAPK function to zygotic function was suggested by the localization for three MAPK pathway enzymes between E2.5 and E3.5, Raf1 phospho is largely cell membrane-localized at E2.5 and E3.5, and MEK1,2 phospho accumulates in the nucleus on E2.5 and E3.5. However, MAPK phospho shifts from nuclear accumulation at E2.5 to cytoplasmic accumulation at E3.5. This finding is similar to the cytoplasmic MAPK phospho localization reported in fibroblast growth factor signaling fields in postimplantation embryos (Corson et al. [2003] Development 130:4527-4537). This spatial and temporal expression study lays a foundation to plan and analyze perturbation studies aimed at understanding the role of the major mitogenic pathway in preimplantation mouse embryos.

    Funded by: NICHD NIH HHS: R01 HD40972A

    Developmental dynamics : an official publication of the American Association of Anatomists 2004;231;1;72-87

  • p19Arf suppresses growth, progression, and metastasis of Hras-driven carcinomas through p53-dependent and -independent pathways.

    Kelly-Spratt KS, Gurley KE, Yasui Y and Kemp CJ

    Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.

    Ectopic expression of oncogenes such as Ras induces expression of p19(Arf), which, in turn, activates p53 and growth arrest. Here, we used a multistage model of squamous cell carcinoma development to investigate the functional interactions between Ras, p19(Arf), and p53 during tumor progression in the mouse. Skin tumors were induced in wild-type, p19(Arf)-deficient, and p53-deficient mice using the DMBA/TPA two-step protocol. Activating mutations in Hras were detected in all papillomas and carcinomas examined, regardless of genotype. Relative to wild-type mice, the growth rate of papillomas was greater in p19(Arf)-deficient mice, and reduced in p53-deficient mice. Malignant conversion of papillomas to squamous cell carcinomas, as well as metastasis to lymph nodes and lungs, was markedly accelerated in both p19 (Arf)- and p53-deficient mice. Thus, p19(Arf) inhibits the growth rate of tumors in a p53-independent manner. Through its regulation of p53, p19(Arf) also suppresses malignant conversion and metastasis. p53 expression was upregulated in papillomas from wild-type but not p19( Arf)-null mice, and p53 mutations were more frequently seen in wild-type than in p19( Arf)-null carcinomas. This indicates that selection for p53 mutations is a direct result of signaling from the initiating oncogenic lesion, Hras, acting through p19(Arf).

    Funded by: NCI NIH HHS: R01 CA099517, T32 CA8046; NIEHS NIH HHS: U01 ES011045, U01 ES11045

    PLoS biology 2004;2;8;E242

  • Phosphorylation of focal adhesion kinase at tyrosine 861 is crucial for Ras transformation of fibroblasts.

    Lim Y, Han I, Jeon J, Park H, Bahk YY and Oh ES

    Department of Life Sciences, Ewha Womans University, Seoul 120-750, Korea.

    Although elevated expression and increased tyrosine phosphorylation of focal adhesion kinase (FAK) are crucial for tumor progression, the mechanism by which FAK promotes oncogenic transformation is unclear. We have therefore determined the role of FAK phosphorylation at tyrosine 861 in the oncogenic transformation of NIH3T3 fibroblasts. FAK phosphorylation at tyrosine 861 was increased in both constitutively H-Ras-transformed and H-Ras-inducible NIH3T3 cells, in parallel with cell transformation. However, H-Ras-inducible cells transfected with the nonphosphorylatable mutant FAK Y861F showed decreased migration/invasion, focus forming activity and anchorage-independent growth, compared with either wild-type or kinase-defective FAK. In contrast to unaltered FAK/Src activity, the association of FAK and p130(CAS) was decreased in FAK Y861F-transfected cells, and FAK phosphorylation at tyrosine 861 enhanced this association in vitro. Consistently, FAK Y861F-transfected cells were defective in activation of c-Jun NH(2)-terminal kinase and in expression of matrix metalloproteinase-9 during transformation. Taken together, these results strongly suggest that FAK phosphorylation at tyrosine 861 is crucial for H-Ras-induced transformation through regulation of the association of FAK with p130(CAS).

    The Journal of biological chemistry 2004;279;28;29060-5

  • Haplotype sharing suggests that a genomic segment containing six genes accounts for the pulmonary adenoma susceptibility 1 (Pas1) locus activity in mice.

    Manenti G, Galbiati F, Giannì-Barrera R, Pettinicchio A, Acevedo A and Dragani TA

    Department of Experimental Oncology, Istituto Nazionale Tumori, Milan, Italy.

    The pulmonary adenoma susceptibility 1 (Pas1) locus affects inherited predisposition and resistance to chemically induced lung tumorigenesis in mice. The A/J and C57BL/6J mouse strains carry the susceptibility and resistance allele, respectively. We identified and genotyped 65 polymorphisms in the Pas1 locus region in 29 mouse inbred strains, and delimited the Pas1 locus to a minimal region of 468 kb containing six genes. That region defined a core Pas1 haplotype with 42 tightly linked markers, including intragenic polymorphisms in five genes (Bcat1, Lrmp, Las1, Ghiso, and Kras2) and amino-acid changes in three genes (Lrmp, Las1, Lmna-rs1). In (A/J x C57BL/6J)F1 mouse lung tumors, the Lmna-rs1 gene was completely downregulated, whereas allele-specific downregulation of the C57BL/6J-derived allele was observed at the Las1 gene, suggesting the potential role of these genes in tumor suppression. These results indicate a complex multigenic nature of the Pas1 locus, and point to a functional role for both intronic and exonic polymorphisms of the six genes of the Pas1 haplotype in lung tumor susceptibility.

    Oncogene 2004;23;25;4495-504

  • G-protein-coupled receptor-mediated activation of rap GTPases: characterization of a novel Galphai regulated pathway.

    Weissman JT, Ma JN, Essex A, Gao Y and Burstein ES

    ACADIA Pharmaceuticals Inc., 3911 Sorrento Valley Blvd, San Diego, CA 92121, USA.

    Ras proteins mediate the proliferative effects of G-protein-coupled receptors (GPCRs), but the role of Rap proteins in GPCR signaling is unclear. We have developed a novel cellular proliferation assay for examining signal transduction to Rap utilizing Ras-rap chimeras that respond selectively to Rap-specific exchange factors, but which stimulate cellular proliferation through Ras effectors. Both the D1 dopamine receptor (Gs-coupled) and the 5HT1E serotonin receptor (Gi-coupled) mediated cellular proliferation in a Ras/rap chimera-dependent manner. Responses to both receptors were PKA-independent. Both receptors activated Ras/rap and full-length Rap as measured by activation-specific probes. Pertussis toxin blocked Ras/rap-dependent responses to 5HT1E but not D1. Ras/rap-dependent responses to both receptors were insensitive to beta-gamma scavengers. Responses to 5HT1E, but not D1, were sensitive to inhibition by a dominant-negative C3G fragment, by the Src-like kinase inhibitors PP1 and PP2, and by a dominant-negative mutant of Src. Very similar data were obtained for two other Gi-coupled receptors, the D2 dopamine receptor and the alpha2C adrenergic receptor. A constitutively active mutant of Galphai2 also mediated Ras/rap-dependent responses. These data indicate that GPCRs coupled to pertussis-toxin-sensitive G-proteins activate Rap through a Galpha subunit, C3G, and Src-dependent pathway.

    Oncogene 2004;23;1;241-9

  • Activated Ras induces lens epithelial cell hyperplasia but not premature differentiation.

    Reneker LW, Xie L, Xu L, Govindarajan V and Overbeek PA

    Department of Ophthalmology, School of Medicine, University of Missouri, Columbia, Missouri, USA. renekerl@health.missouri.edu

    Growth factor signaling is implicated in the regulation of lens cell proliferation and differentiation during development. Activation of growth factor receptor tyrosine kinases is known to activate Ras proteins, small GTP-binding proteins that function as part of the signal transduction machinery. In the present study, we examined which classical Ras genes are expressed in lens cells during normal development and whether expression of an activated version of Ras is sufficient to induce either lens cell proliferation or fiber cell differentiation in transgenic mice. In situ hybridization showed H-Ras, K-Ras and N-Ras are ubiquitously expressed in all cells of the embryonic (E13.5) eye, with N-Ras showing the highest level of expression. The expression level of N-Ras decreases during later stages of embryonic development, and is nearly undetected in postnatal day 21 lenses. To generate transgenic mice, a constitutively active H-Ras mutant was linked to a chimeric regulatory element containing the mouse alphaA-crystallin promoter fused to the chick delta1-crystallin lens enhancer element. In the lenses of the transgenic mice, the transgene was expressed in both lens epithelial and fiber cells. Expression of activated Ras was sufficient to stimulate lens cell proliferation but not differentiation, implying that alternative or additional signal transduction pathways are required to induce fiber cell differentiation.

    Funded by: NEI NIH HHS: EY10448, EY13146, EY14795

    The International journal of developmental biology 2004;48;8-9;879-88

  • Role of Ras signaling in erythroid differentiation of mouse fetal liver cells: functional analysis by a flow cytometry-based novel culture system.

    Zhang J, Socolovsky M, Gross AW and Lodish HF

    Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA.

    Ras signaling plays an important role in erythropoiesis. Its function has been extensively studied in erythroid and nonerythroid cell lines as well as in primary erythroblasts, but inconclusive results using conventional erythroid colony-forming unit (CFU-E) assays have been obtained concerning the role of Ras signaling in erythroid differentiation. Here we describe a novel culture system that supports terminal fetal liver erythroblast proliferation and differentiation and that closely recapitulates erythroid development in vivo. Erythroid differentiation is monitored step by step and quantitatively by a flow cytometry analysis; this analysis distinguishes CD71 and TER119 double-stained erythroblasts into different stages of differentiation. To study the role of Ras signaling in erythroid differentiation, different H-ras proteins were expressed in CFU-E progenitors and early erythroblasts with the use of a bicistronic retroviral system, and their effects on CFU-E colony formation and erythroid differentiation were analyzed. Only oncogenic H-ras, not dominant-negative H-ras, reduced CFU-E colony formation. Analysis of infected erythroblasts in our newly developed system showed that oncogenic H-ras blocks terminal erythroid differentiation, but not through promoting apoptosis of terminally differentiated erythroid cells. Rather, oncogenic H-ras promotes abnormal proliferation of CFU-E progenitors and early erythroblasts and supports their erythropoietin (Epo)-independent growth.

    Funded by: NHLBI NIH HHS: P01 HL 32262

    Blood 2003;102;12;3938-46

  • Wnk1 kinase deficiency lowers blood pressure in mice: a gene-trap screen to identify potential targets for therapeutic intervention.

    Zambrowicz BP, Abuin A, Ramirez-Solis R, Richter LJ, Piggott J, BeltrandelRio H, Buxton EC, Edwards J, Finch RA, Friddle CJ, Gupta A, Hansen G, Hu Y, Huang W, Jaing C, Key BW, Kipp P, Kohlhauff B, Ma ZQ, Markesich D, Payne R, Potter DG, Qian N, Shaw J, Schrick J, Shi ZZ, Sparks MJ, Van Sligtenhorst I, Vogel P, Walke W, Xu N, Zhu Q, Person C and Sands AT

    Lexicon Genetics, 8800 Technology Forest Place, The Woodlands, TX 77381, USA. brian@lexgen.com

    The availability of both the mouse and human genome sequences allows for the systematic discovery of human gene function through the use of the mouse as a model system. To accelerate the genetic determination of gene function, we have developed a sequence-tagged gene-trap library of >270,000 mouse embryonic stem cell clones representing mutations in approximately 60% of mammalian genes. Through the generation and phenotypic analysis of knockout mice from this resource, we are undertaking a functional screen to identify genes regulating physiological parameters such as blood pressure. As part of this screen, mice deficient for the Wnk1 kinase gene were generated and analyzed. Genetic studies in humans have shown that large intronic deletions in WNK1 lead to its overexpression and are responsible for pseudohypoaldosteronism type II, an autosomal dominant disorder characterized by hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Consistent with the human genetic studies, Wnk1 heterozygous mice displayed a significant decrease in blood pressure. Mice homozygous for the Wnk1 mutation died during embryonic development before day 13 of gestation. These results demonstrate that Wnk1 is a regulator of blood pressure critical for development and illustrate the utility of a functional screen driven by a sequence-based mutagenesis approach.

    Proceedings of the National Academy of Sciences of the United States of America 2003;100;24;14109-14

  • Alternative splicing of the human proto-oncogene c-H-ras renders a new Ras family protein that trafficks to cytoplasm and nucleus.

    Guil S, de La Iglesia N, Fernández-Larrea J, Cifuentes D, Ferrer JC, Guinovart JJ and Bach-Elias M

    Centre d'Investigació Cardiovascular-Consejo Superior de Investigaciones Científicas, Barcelona, Spain.

    We characterized a novel protein of the Ras family, p19 (H-RasIDX). The c-H-ras proto-oncogene undergoes alternative splicing of the exon termed IDX. We show that the alternative p19 mRNA is stable and as abundant as p21 (p21 H-Ras4A) mRNA in all of the human tissues and cell lines tested. IDX is spliced into stable mRNA in different mammalian species, which present a high degree of nucleotide conservation. Both the endogenous and the transiently expressed p19 protein are detected in COS-1 and HeLa cells and show nuclear diffuse and speckled patterns as well as cytoplasmic localization. In yeast two-hybrid assays, p19 did not interact with two known p21 effectors, Raf1 and Rin1, but was shown to interact with RACK1, a scaffolding protein that promotes multiprotein complexes in different signaling pathways. This observation suggests that p19 and p21 play differential and complementary roles in the cell.

    Cancer research 2003;63;17;5178-87

  • Allele-specific Hras mutations and genetic alterations at tumor susceptibility loci in skin carcinomas from interspecific hybrid mice.

    Nagase H, Mao JH and Balmain A

    The Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA. Hiroki.Nagase@RoswellPark.org

    We have investigated the effects of germ-line variants that influence skin tumor susceptibility loci on the patterns of somatic genetic alterations in mouse skin cancers. Using a two-stage skin carcinogenesis model, we previously identified at least 13 skin tumor susceptibility (Skts) loci in a large interspecific F1 backcross [(NIH/Ola x M. spretus) x NIH/Ola] study. In this report, we describe the analysis of allele-specific alterations at these loci in skin tumors from the same backcross animals. The mouse Hras gene, located close to Skts2 on chromosome 7, had specific activating mutations in the Mus musculus allele in 23 of 26 carcinomas. In all cases, tumors with Hras mutations also showed specific imbalance of chromosome 7 markers that favored the chromosome carrying the mutant allele. Allele-specific quantitative microsatellite analysis was also carried out, using DNA from 62 carcinomas from (NIH/Ola x M. spretus) x NIH/Ola mice. Frequent allelic imbalance was detected at five additional tumor-susceptibility loci on chromosomes 4, 6, 7, 9, and 16 (Skts7, Skts12, Skts1, Skts6, and Skts9, respectively). At all except Skts7, we found loss of the allele inherited from the resistant strain or amplification of the allele from the susceptible strain. We conclude that polymorphisms in some low-penetrance tumor modifier genes are reflected in the pattern of somatic alterations in tumors. Analysis of such allele-specific changes in tumors may facilitate the identification of functional germ-line variants that control tumor susceptibility.

    Funded by: NCI NIH HHS: CA16056

    Cancer research 2003;63;16;4849-53

  • Ha-ras overexpression mediated cell apoptosis in the presence of 5-fluorouracil.

    Tseng YS, Tzeng CC, Chiu AW, Lin CH, Won SJ, Wu IC and Liu HS

    Department of Microbiology and Immunology, National Cheng Kung University, College of Medicine, Tainan, Taiwan.

    By using a mouse NIH3T3 derivate designed 7-4 harboring the inducible Ha-ras oncogene, we demonstrated the close relationship between Ha-ras expression level and sensitization of 5-flurouracil (5-FU)-treated cells. Further studies revealed that the cells susceptible to 5-FU treatment died of apoptosis, which was demonstrated by caspase-3 activation, loss of mitochondria membrane potential (MMP), and DNA fragmentation. The 7-4 cells coexpressing dominant negative Ras (Ras(Asn17)), dominant negative Raf-1 (Raf-1(CB4)), Bcl-2, or active form of phosphatidylinositol 3-kinase (PI3K) became resistant to 5-FU, and apoptosis was prevented. In contrast, the cells coexpressing dominant negative Rac 1 (Rac1(Asn17)) or dominant negative Rho A (RhoA(Asn19)) showed no change of sensitivity to 5-FU. These results indicate that Ras, Bcl-2, as well as Raf-1 and PI3K pathways play pivotal roles in 5-FU-induced apoptosis under Ha-ras-overexpressed condition. Aberrant levels of cyclin E and p21(Cip/WAF-1) expression as well as Cdc 2 phosphorylation at Tyrosine 15 suggest that perturbation of G1/S and G2/M transitions in cell cycle might be responsible for 5-FU triggered apoptosis. Sensitization of Ha-ras-related cells to 5-FU was also demonstrated in human bladder cancer cells. Through understanding the mechanism of 5-FU induced apoptosis in tumor cells, a new direction toward the treatment of Ha-ras oncogene-related cancers with 5-FU at more optimal dosages is possible and combinational therapy with other drugs that suppress PI3K and Bcl-2 activities can also be considered.

    Experimental cell research 2003;288;2;403-14

  • The p53-dependent effects of macrophage migration inhibitory factor revealed by gene targeting.

    Fingerle-Rowson G, Petrenko O, Metz CN, Forsthuber TG, Mitchell R, Huss R, Moll U, Müller W and Bucala R

    The Picower Institute for Medical Research, Manhasset, NY 11030, USA. g.fingerle-rowson@gmx.de

    Macrophage migration inhibitory factor (MIF) is a mediator of host immunity and functions as a high, upstream activator of cells within the innate and the adaptive immunological systems. Recent studies have suggested a potentially broader role for MIF in growth regulation because of its ability to antagonize p53-mediated gene activation and apoptosis. To better understand MIF's activity in growth control, we generated and characterized a strain of MIF-knockout (MIF-KO) mice in the inbred, C57BL/6 background. Embryonic fibroblasts from MIF-KO mice exhibit p53-dependent growth alterations, increased p53 transcriptional activity, and resistance to ras-mediated transformation. Concurrent deletion of the p53 gene in vivo reversed the observed phenotype of cells deficient in MIF. In vivo studies showed that fibrosarcomas induced by the carcinogen benzo[alpha]pyrene are smaller in size and have a lower mitotic index in MIF-KO mice relative to their WT counterparts. The data provide direct genetic evidence for a functional link between MIF and the p53 tumor suppressor and indicate an important and previously unappreciated role for MIF in carcinogenesis.

    Funded by: NIAID NIH HHS: R01 AI042310, R01-AI42310; NIAMS NIH HHS: 1R01AR45918, R01 AR045918, R01-ARO49610; NINDS NIH HHS: NS-42809, R01 NS042809

    Proceedings of the National Academy of Sciences of the United States of America 2003;100;16;9354-9

  • Modulation of the angiogenesis response through Ha-ras control, placenta growth factor, and angiopoietin expression in mouse skin carcinogenesis.

    Larcher F, Franco M, Bolontrade M, Rodriguez-Puebla M, Casanova L, Navarro M, Yancopoulos G, Jorcano JL and Conti CJ

    Project on Molecular and Cell Biology and Gene Therapy entro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain.

    Tumor angiogenesis is governed by a complex balance of positive and negative angiogenic factors. Development of chemically-induced mouse skin tumors appears to be highly dependent on an early burst of neovascularization. We have previously shown that Ha-ras-driven vascular endothelial growth factor (VEGF) expression plays a pivotal role in this process. However, the status of other critical positive and negative angiogenic factors throughout skin tumorigenesis has not been studied to the same extent. In the present study, we show that another VEGF family member, placenta growth factor (PlGF), was highly upregulated at all tumor stages in a ras-dependent manner. The study of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), ligands of receptor tyrosine kinase 2 (Tie-2), showed that while stroma-derived Ang-2 was increased, epidermal Ang-1 expression was completely abolished at early papilloma formation. Studies using epidermal tumor cell lines suggest that the disappearance of Ang-1 also depends on ras activation, extending the plethora of events controlled by this oncogene in mouse skin carcinogenesis. Our results indicated that tumor development occurred in a strong angiogenesis-prone scenario in which PlGF and Ang-2 acted cooperatively with VEGF, whereas the negative or stabilizing effect of Ang-1 was abrogated. A time-course sequence of expression of angiogenic factors expressed throughout tumor growth, as well as the identification of key signaling molecules triggering the angiogenic response, may contribute to the development and testing of antiangiogenic therapeutic strategies with this in vivo tumor model.

    Funded by: NCI NIH HHS: CA 16672, R01 CA 76450; NIEHS NIH HHS: ES 007784

    Molecular carcinogenesis 2003;37;2;83-90

  • Oncogenic Ha-Ras transformation modulates the transcription of the CTP:phosphocholine cytidylyltransferase alpha gene via p42/44MAPK and transcription factor Sp3.

    Bakovic M, Waite K and Vance DE

    Department of Biochemistry and Canadian Institutes of Health Research Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.

    We have shown previously that expression of the murine CTP:phosphocholine cytidylyltransferase (CT) alpha gene is regulated during cell proliferation (Golfman, L. S., Bakovic, M., and Vance, D. E. (2001) J. Biol. Chem. 276, 43688-43692). We have now characterized the role of Ha-Ras in the transcriptional regulation of the CTalpha gene. The expression of CTalpha and CTbeta2 proteins and mRNAs was stimulated in C3H10T1/2 murine fibroblasts expressing oncogenic Ha-Ras. Incubation of cells with the specific inhibitor (PD98059) of p42/44(MAPK) decreased the expression of both CT isoforms. Transfection of fibroblasts with CTalpha promoter-luciferase constructs resulted in an approximately 2-fold enhanced luciferase expression in Ha-Ras-transformed, compared with nontransformed, fibroblasts. Electromobility shift assays indicated enhanced binding of the Sp3 transcription factor to the CTalpha promoter in Ha-Ras-transformed cells. Expression of several forms of Sp3 was increased in nuclear extracts of Ha-Ras-transformed fibroblasts compared with nontransformed cells. Tyrosine phosphorylation of one Sp3 form was decreased, whereas phosphorylation of two other forms of Sp3 was increased in nuclear extracts of Ha-Ras-transformed cells. When control fibroblasts were transfected with a Sp3-expressing plasmid, an enhanced expression of CTalpha and CTbeta was observed. However, the expression of CTalpha or CTbeta was not increased in Ha-Ras-transformed cells transfected with a Sp3 plasmid presumably because expression was already maximally enhanced. The results suggest that Sp3 is a downstream effector of a Ras/p42/44(MAPK) signaling pathway which increases CTalpha gene transcription.

    The Journal of biological chemistry 2003;278;17;14753-61

  • The cyclopentenone 15-deoxy-delta 12,14-prostaglandin J2 binds to and activates H-Ras.

    Oliva JL, Pérez-Sala D, Castrillo A, Martínez N, Cañada FJ, Boscá L and Rojas JM

    Unidad de Biologia Celular, Centro Nacional de Microbiologia, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain.

    The cyclopentenone 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) induces cell proliferation and mitogen-activated protein kinase activation. Here, we describe that these effects are mediated by 15d-PGJ(2)-elicited H-Ras activation. We demonstrate that this pathway is specific for H-Ras through the formation of a covalent adduct of 15d-PGJ(2) with Cys-184 of H-Ras, but not with N-Ras or K-Ras. Mutation of C184 inhibited H-Ras modification and activation by 15d-PGJ(2), whereas serum-elicited stimulation was not affected. These results describe a mechanism for the activation of the Ras signaling pathway, which results from the chemical modification of H-Ras by formation of a covalent adduct with cyclopentenone prostaglandins.

    Proceedings of the National Academy of Sciences of the United States of America 2003;100;8;4772-7

  • Biallelic expression of HRAS and MUCDHL in human and mouse.

    Goldberg M, Wei M, Yuan L, Murty VV and Tycko B

    Department of Pediatrics, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA.

    At least eight genes clustered in 1 Mb of DNA on human chromosome (Chr) 11p15.5 are subject to parental imprinting, with monoallelic expression in one or more tissues. Orthologues of these genes show conserved linkage and imprinting on distal Chr 7 of mice. The extended imprinted region has a bipartite structure, with at least two differentially methylated DNA elements (DMRs) controlling the imprinting of two sub-domains. We previously described three biallelically expressed genes ( MRPL23, 2G7 and TNNT3) in 100 kb of DNA immediately downstream of the imprinted H19 gene, suggesting that H19 marks one border of the imprinted region. Here we extend this analysis to two additional downstream genes, HRAS and MUCDHL (mu-protocadherin). We find that these genes are biallelically expressed in multiple fetal and adult tissues, both in humans and in mice. The mouse orthologue of a third gene, DUSP8, located between H19 and MUCDHL, is also expressed biallelically. The DMR immediately upstream of H19 frequently shows a net gain of methylation in Wilms tumors, either via Chr 11p15.5 loss of heterozygosity (LOH) or loss of imprinting (LOI), but changes in methylation in CpG-rich sequences upstream and within the MUCDHL gene are rare in these tumors and do not correlate with LOH or LOI. These findings are further evidence for a border of the imprinted region immediately downstream of H19, and the data allow the construction of an imprinting map that includes more than 20 genes, distributed over 3 Mb of DNA on Chr 11p15.5.

    Funded by: NCI NIH HHS: R01 CA60765

    Human genetics 2003;112;4;334-42

  • Small GTPase Rah/Rab34 is associated with membrane ruffles and macropinosomes and promotes macropinosome formation.

    Sun P, Yamamoto H, Suetsugu S, Miki H, Takenawa T and Endo T

    Department of Biology, Faculty of Science, and Graduate School of Science and Technology, Chiba University, Yayoicho, Inageku, Japan.

    Macropinocytosis is an efficient process for the uptake of nutrients and solute macromolecules into cells from the external environment. Macropinosomes, which are surrounded by actin, are formed from the cell surface membrane ruffles and migrate toward the cell center. We have cloned the entire coding sequence of a member of the Rab family small GTPases, Rah/Rab34. It lacked a consensus sequence for GTP-binding/GTPase domain. Although wild-type Rah exhibited extremely low GTPase activity in vitro, it exerted appreciable GTPase activity in vivo. In fibroblasts, Rah was colocalized with actin to the membrane ruffles and membranes of relatively large vesicles adjacent to the ruffles. These vesicles were identified as macropinosomes on the basis of several criteria. Rah and Rab5 coexisted in some, but not all, macropinosomes. Rah was predominantly associated with nascent macropinosomes, whereas Rab5 was present in endosomes at later stages. The number of macropinosomes in the cells overexpressing Rah increased about 2-fold. The formation of macropinosomes by the treatment of platelet-derived growth factor or phorbol ester was also facilitated by Rah but suppressed by a dominant-negative Rah. Rah-promoted macropinosome formation was retarded by dominant-negative mutants of Rac1 and WAVE2, which are essential for membrane ruffling. These results imply that Rah is required for efficient macropinosome formation from the membrane ruffles.

    The Journal of biological chemistry 2003;278;6;4063-71

  • Impaired Ras membrane association and activation in PPARalpha knockout mice after partial hepatectomy.

    Wheeler MD, Smutney OM, Check JF, Rusyn I, Schulte-Hermann R and Thurman RG

    Laboratory of Hepatobiology and Toxicology, Department of Pharmacology, Curriculum in Toxicology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA. wheelmi@med.unc.edu

    Liver regeneration after partial hepatectomy (PH) involves several signaling mechanisms including activation of the small GTPases Ras and RhoA in response to mitogens leading to DNA synthesis and cell proliferation. Peroxisome proliferator-activated receptor-alpha (PPARalpha) regulates the expression of several key enzymes in isoprenoid synthesis, which are key events for membrane association of Ras and RhoA. Thus the role of PPARalpha in cell proliferation after PH was tested. After PH, an increase in PPARalpha DNA binding was observed in wild-type mice, correlating with an increase in the PPARalpha-regulated enzyme acyl-CoA oxidase. In addition, the PPARalpha-regulated genes farnesyl pyrophosphate synthase and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase were significantly increased in wild-type mice. However, these increases were not observed in PPARalpha knockout (PPARalpha -/-) mice. The peak in DNA synthesis observed 42 h after PH was reduced by approximately 60% in PPARalpha -/- mice, despite increases in TNF-alpha and IL-1. Also, under these conditions, membrane association of Ras was high in wild-type mice after PH but was impaired in PPARalpha -/- mice. Accordingly, Ras was significantly elevated in the cytosol in PPARalpha -/- mice. This observation correlated with lower levels of active GTP-bound Ras after PH in PPARalpha -/- mice compared with wild-type mice. Similar observations were made for RhoA. Moreover, deletion of PPARalpha blunted the activation of cyclin-dependent kinase (cdk)2/cyclin E and cdk4/cyclin D complexes. Collectively, these results support the hypothesis that PPARalpha is necessary for cell cycle progression in regenerating mouse liver via mechanisms involving prenylation of small GTPases Ras and RhoA.

    American journal of physiology. Gastrointestinal and liver physiology 2003;284;2;G302-12

  • Elevated phospholipase D activity in H-Ras- but not K-Ras-transformed cells by the synergistic action of RalA and ARF6.

    Xu L, Frankel P, Jackson D, Rotunda T, Boshans RL, D'Souza-Schorey C and Foster DA

    Department of Biological Sciences, Hunter College of The City University of New York, New York, New York 10021, USA.

    Phospholipase D (PLD) activity is elevated in response to the oncogenic stimulus of H-Ras but not K-Ras. H-Ras and K-Ras have been reported to localize to different membrane microdomains, with H-Ras localizing to caveolin-enriched light membrane fractions. We reported previously that PLD activity elevated in response to mitogenic stimulation is restricted to the caveolin-enriched light membrane fractions. PLD activity in H-Ras-transformed cells is dependent upon RalA, and consistent with a lack of elevated PLD activity in K-Ras-transformed cells, RalA was not activated in K-Ras-transformed cells. Although H-Ras-induced PLD activity is dependent upon RalA, an activated mutant of RalA is not sufficient to elevate PLD activity. We reported previously that RalA interacts with PLD activating ADP ribosylation factor (ARF) proteins. In cells transformed by H-Ras, we found increased coprecipitation of ARF6 with RalA. Moreover, ARF6 colocalized with RalA in light membrane fractions. Interestingly, ARF6 protein levels were elevated in H-Ras- but not K-Ras-transformed cells. A dominant-negative mutant of ARF6 inhibited PLD activity in H-Ras-transformed NIH 3T3 cells. Activated mutants of either ARF6 or RalA were not sufficient to elevate PLD activity in NIH 3T3 cells; however, expression of both activated RalA and activated ARF6 in NIH 3T3 cells led to increased PLD activity. These data suggest a model whereby H-Ras stimulates the activation of both RalA and ARF6, which together lead to the elevation of PLD activity.

    Funded by: NCI NIH HHS: CA46677, R01 CA046677; NCRR NIH HHS: G12 RR003037, RR-03037; NIGMS NIH HHS: GM60654, S06 GM060654

    Molecular and cellular biology 2003;23;2;645-54

  • The p85 regulatory subunit controls sequential activation of phosphoinositide 3-kinase by Tyr kinases and Ras.

    Jimenez C, Hernandez C, Pimentel B and Carrera AC

    Department of Immunology and Oncology, Centro Nacional de Biotecnologia, Universidad Autónoma de Madrid, Cantoblanco, Spain.

    Class IA phosphoinositide 3-kinase (PI3K) is a heterodimer composed of a p85 regulatory and a p110 catalytic subunit that regulates a variety of cell responses, including cell division and survival. PI3K is activated following Tyr kinase stimulation and by Ras. We found that the C-terminal region of p85, including the C-Src homology 2 (C-SH2) domain and part of the inter-SH2 region, protects the p110 catalytic subunit from Ras-induced activation. Although the p110 activity associated with a C-terminal p85 deletion mutant increased significantly in the presence of an active form of Ras, purified wild type p85-p110 was only slightly stimulated by active Ras. Nonetheless, incubation of purified p85-p110 with Tyr-phosphorylated peptides, which mimic the activated platelet-derived growth factor receptor, restored Ras-induced p85-p110 activation. In conclusion, p85 inhibits p110 activation by Ras; this blockage is released by Tyr kinase stimulation, showing that the classical mechanism of class IA PI3K stimulation mediated by Tyr kinases also regulates Ras-induced PI3K activation.

    The Journal of biological chemistry 2002;277;44;41556-62

  • Genetic interaction between the unstable v-Ha-RAS transgene (Tg.AC) and the murine Werner syndrome gene: transgene instability and tumorigenesis.

    Leder A, Lebel M, Zhou F, Fontaine K, Bishop A and Leder P

    Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, 200 Longwood Ave., Boston, Massachusetts, MA 02115, USA. Leder@rascal.med.harvard.edu

    Tg.AC transgenic mice provide a sensitive assay for oncogenic agents and a convenient alternative to the two-stage initiation/promoter model of skin tumorigenesis. Although extensively used, this model has remained in part an enigma since mice that carry the Tg.AC transgene (consisting of v-Ha-Ras driven by an embryonic zeta-globin promoter) would not ordinarily be expected to develop skin and other adult tumors. Cloning and characterizing the inserted transgene has provided an insight into the Tg.AC phenotype. We find that the transgene is inserted into a Line-1 element in such a way as to create extended inverted repeats consisting of both transgene and Line-1 sequences. Such structures would be expected to contribute to the instability of the Tg.AC locus and we suggest that this instability is critical to the Tg.AC phenotype. Further, we strengthen this notion by introducing an inactivating mutation in the murine Wrn gene (a gene important in maintenance of genome stability) and showing that bigenic Tg.AC/Wrn(Deltahel/Deltahel) mice experience an eightfold increase in inactivating germline mutations at the Tg.AC locus. Similarly, Tg.AC/Wrn(Deltahel/Deltahel) mice that retain an intact and thus active Tg.AC locus experience a sharp increase in papillomas as compared to Tg.AC/Wrn(+/+) mice. This work demonstrates a genetic interaction between the instability of the multicopy transgene and the Werner Syndrome gene. From this, we conclude that genetic instability remains a key element in this tumor promoter model.

    Oncogene 2002;21;43;6657-68

  • Metastasis is driven by sequential elevation of H-ras and Smad2 levels.

    Oft M, Akhurst RJ and Balmain A

    University of California at San Francisco Comprehensive Cancer Center, Box 0875, San Francisco, California 94143-0875, USA.

    Metastasis is a multistep process that involves local tumour invasion followed by dissemination to, and re-establishment at, distant sites. Here we show that during multistage tumorigenesis, discrete expression thresholds of activated Smad2 and H-ras are sequentially surpassed, driving tumour progression through distinct phases from a differentiated squamous carcinoma to a motile invasive stage, followed by an overt change from epithelial to mesenchymal cell type, finally culminating in metastatic tumour spread. Smad2 activation alone induces migration of tumour cells. Elevated H-ras levels, however, are required for nuclear accumulation of Smad2, both of which are essential for the epithelial mesenchymal transition (EMT). Having undergone EMT, fibroblastoid carcinoma cells with elevated levels of activated Smad2, gain the capability to spread to a wide variety of tissues by a further increase in Smad2 expression. These findings have far-reaching implications for the prevention of tumour growth, invasion and metastasis.

    Funded by: NCI NIH HHS: K01 CA84244

    Nature cell biology 2002;4;7;487-94

  • A critical role for ras-mediated, epidermal growth factor receptor-dependent angiogenesis in mouse skin carcinogenesis.

    Casanova ML, Larcher F, Casanova B, Murillas R, Fernández-Aceñero MJ, Villanueva C, Martínez-Palacio J, Ullrich A, Conti CJ and Jorcano JL

    Project on Cell and Molecular Biology and Gene Therapy, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, 28040 Madrid, Spain.

    Epidermal growth factor receptor (EGFR) plays a critical role in epidermal biology. Abnormal EGFR function has been described in epithelial tumors including those induced by two-stage chemical carcinogenesis in mouse skin. A large body of evidence indicates that in this model, activation of Ha-ras is the critical event in papilloma formation, a process that involves epidermal proliferation and stroma remodeling, which includes angiogenesis. This study reports that activated Ha-ras results in a dramatic induction of EGFR in epidermal tumor cells and provides experimental evidence that EGFR signaling is responsible for Ha-ras-dependent vascular endothelial growth factor (VEGF) induction, as well as for the repression of other angiogenic factors such as angiopoietin 1. The pivotal role of functional EGFR in throwing the angiogenic switch necessary for tumor growth was confirmed by s.c. injection of immunodeficient mice with epidermal tumor cells carrying a dominant negative (dn) EGFR and by in vivo chemical skin carcinogenesis assays in transgenic mice expressing the same dn EGFR form in the epidermis. Immunohistochemical analysis of the tumors obtained by both ex vivo and in vivo approaches showed that dn EGFR expression abolished the changes in blood vessels that occurred during tumor progression. A strong reduction of VEGF expression in dn EGFR tumors appears to be the key event responsible for angiogenesis and tumor growth suppression. The apoptotic rate was increased, and Akt activity was decreased, suggesting that impaired nutrient and oxygen supply might contribute to diminished cell survival in dn EGFR tumors. Support for this mechanism is provided by the fact that the ectopic expression of VEGF in dn EGFR-expressing tumor cell lines restored tumor growth capacity. Although ras activation might suffice for epidermal transformation and the stroma-remodeling events of tumor induction, such effects may not be operative without a functional upstream EGFR. It is tempting to speculate that EGFR family members may function as angiogenic regulators in other epithelial tumors such as those of the colon, breast, and prostate, reinforcing their value as targets for therapeutic intervention.

    Funded by: NCI NIH HHS: R01 CA 76540

    Cancer research 2002;62;12;3402-7

  • Occurrence of H-ras codon 61 CAA to AAA mutation during mouse liver tumor progression.

    Parsons BL, Culp SJ, Manjanatha MG and Heflich RH

    Division of Genetic and Reproductive Toxicology and Division of Biochemical Toxicology, HFT-120, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA. bparsons@nctr.fda.gov

    The initiating mutations of a tumor are present in each of the cancerous cells comprising the tumor. Identification and measurement of the subsequent mutations that occur during tumor progression, however, requires mutation detection in a smaller subset of the tumor cells. In this study, allele-specific competitive blocker PCR (ACB-PCR), a genotypic selection method with the sensitivity to detect a specific point mutation in the presence of a 10(5)-fold excess of wild-type DNA sequence, was used to measure H-ras codon 61 CAA to AAA mutation in mouse liver tumors that did not have this mutation as an initiating event. Twenty-one spontaneous or chemically induced mouse liver tumors, negative for the H-ras codon 61 CAA to AAA mutation by DNA sequencing or denaturing gradient gel electrophoresis, were analyzed for this mutation by ACB-PCR. The mutation was detected at some level in 71% of these tumors. The mutation was detected in adenomas and carcinomas more frequently (13 of 14 tumors) and at significantly higher mutant fractions than it was detected in histiocytic sarcomas (1 of 5 tumors). These data indicate that the same oncogenic point mutation that can be identified as a tumor-initiating event based on its clonal amplification in a tumor can also be present in only a small sub-population of tumor cells where the mutation must have been fixed at a later stage in tumor development. The occurrence of a mutation as a primary or secondary event probably reflects the stochastic nature of mutation and is likely to be affected by the mutation rate for each target site.

    Carcinogenesis 2002;23;6;943-8

  • Oncogenic H-Ras enhances DNA repair through the Ras/phosphatidylinositol 3-kinase/Rac1 pathway in NIH3T3 cells. Evidence for association with reactive oxygen species.

    Cho HJ, Jeong HG, Lee JS, Woo ER, Hyun JW, Chung MH and You HJ

    Department of Pharmacology, School of Medicine, the Research Center for Proteineous Materials, Chosun University, 375 Seosuk-dong, Kwangju 501-759, Korea. hjyou@mail.chosun.ac.kr

    This study investigated the role of oncogenic H-Ras in DNA repair capacity in NIH3T3 cells. Expression of dominant-positive H-Ras (V12-H-Ras) enhanced the host cell reactivation of luciferase activity from UV-irradiated and cisplatin-treated plasmids and also increased the unscheduled DNA synthesis following cisplatin or UV treatment of cells. This observed enhancement of DNA repair capacity was inhibited by transient transfection with dominant-negative H-Ras (N17-H-Ras) or Rac1 (N17-Rac1) plasmids. Moreover, stable transfection of dominant-positive Rac1 (V12-Rac1) further enhanced DNA repair capacity. Because reactive oxygen species (ROS) are known to be a downstream effector of oncogenic Ras, we examined the role of ROS in DNA repair capacity. We found that ROS production by V12-H-Ras expression was mediated by the Ras/phosphatidylinositol 3-kinase (PI3K)/Rac1/NADPH oxidase-dependent pathway and that pretreatment of V12-H-Ras-transformed cells with an antioxidant (N-acetylcysteine) and an NADPH oxidase inhibitor (diphenyleneiodonium) decreased DNA repair capacity. Similarly, treatment with PI3K inhibitors (wortmannin and LY294002) inhibited the ability of oncogenic H-Ras to enhance DNA repair capacity. Furthermore, inhibition of the Ras/PI3K/Rac1/NADPH oxidase pathway resulted in increased sensitivity to cisplatin and UV in V12-H-Ras-expressing NIH3T3 cells. Taken together, these results provide evidence that oncogenic H-Ras activates DNA repair capacity through the Ras/PI3K/Rac1/NADPH oxidase-dependent pathway and that increased ROS production via this signaling pathway is required for enhancement of the DNA repair capacity induced by oncogenic H-Ras.

    The Journal of biological chemistry 2002;277;22;19358-66

  • Ferritin expression modulates cell cycle dynamics and cell responsiveness to H-ras-induced growth via expansion of the labile iron pool.

    Kakhlon O, Gruenbaum Y and Cabantchik ZI

    Department of Biological Chemistry, Institute of Life Sciences, Hebrew University, Jerusalem, 91904, Israel.

    Repression or overexpression of ferritin accelerated or retarded cell cycling respectively, via changes in the cellular labile iron pool (LIP). A rise in LIP is caused by ferritin repression enhanced growth, induced by H-ras, and reverted growth arrest is induced by dominant negative H-ras. The studies indicate that repression of ferritin expression provides a mechanism by which certain oncogenes lead to cell growth stimulation.

    The Biochemical journal 2002;363;Pt 3;431-6

  • Sodium arsenite administration via drinking water increases genome-wide and Ha-ras DNA hypomethylation in methyl-deficient C57BL/6J mice.

    Okoji RS, Yu RC, Maronpot RR and Froines JR

    Center for Occupational and Environmental Health, UCLA School of Public Health, 650 Charles E. Young Drive South, Los Angeles, CA 90095, USA.

    Arsenic is an established human carcinogen. Deficiencies in available animal models have inhibited a detailed analysis of the mechanism of arsenic induced cancer. This study sought to determine the role of a methyl-deficient diet in combination with sodium arsenite on the genomic methylation status and Ha-ras methylation status of C57BL/6J male mice hepatic DNA. Mice were administered arsenic as sodium arsenite via drinking water at 0, 2.6, 4.3, 9.5 or 14.6 mg sodium arsenite/kg/day. Administration occurred 7 days a week for 130 days. Dose-related effects on the liver were evident in mice administered arsenic and methyl-deficient diets. Most prominent were observations of steatosis and microgranulomas. Sodium arsenite increased genomic hypomethylation in a dose dependent manner and methyl-deficiency and sodium arsenite reduced the frequency of methylation at several cytosine sites within the promoter region of the oncogenic gene, Ha-ras. Methylation changes were prominent in a 500 bp non-CpG island-like region of the Ha-ras promoter and less prominent in a 525 bp CpG island-like region. DNA methylation plays an important role in the physiological expression of many genes including Ha-ras. Significantly reduced methylation at a key regulatory region of Ha-ras in the mouse liver may have relevance to understanding arsenic-induced perturbations in the methylation patterns of cellular growth genes involved in the formation of tumors. These findings highlight the effect of sodium arsenite on inherent methylation processes within the hepatic cell.

    Funded by: NIEHS NIH HHS: 5P30ES07048-06

    Carcinogenesis 2002;23;5;777-85

  • Transgene stability and features of rasH2 mice as an animal model for short-term carcinogenicity testing.

    Suemizu H, Muguruma K, Maruyama C, Tomisawa M, Kimura M, Hioki K, Shimozawa N, Ohnishi Y, Tamaoki N and Nomura T

    Central Institute for Experimental Animals, Nogawa, Miyamae-ku, Kawasaki-shi, Japan.

    The transgenic mouse rasH2 line, in which the mouse carries the human c-Ha-ras gene under the control of its own enhancer and promoter, has been proposed as one of the alternative short-term models for carcinogenicity testing. To apply this purpose, we have produced a genetically homogeneous population as C57BL/6JJic-TgN(RASH2) (Tg-rasH2) by continuous backcrossing. In this study, we examined the transgene stability between different generations and the detailed transgene architecture of the integrated human c-Ha-ras gene. Fluorescence in situ hybridization analysis showed that the integrated human c-Ha-ras gene was stably located on chromosome 15E3 in Tg-rasH2 mice at generation number (N) 15 and 20. Southern and Northern blot analysis did not show any differences in the hybridized band pattern in each generation. Southern blot analyses showed that the Tg-rasH2 mouse contained three copies of the human c-Ha-ras gene arrayed in a head-to-tail configuration. We also determined the nucleotide sequence of the transgene in the Tg-rasH2 mouse at N20 and confirmed that the sequence of the coding region was perfectly matched with human c-Ha-ras cDNA. Cloning and sequencing of genome/transgene junctions revealed that integration of the microinjected human c-Ha-ras gene into mouse host genome resulted in a 1820-bp deletion in the rasH2 line. The deleted sequence did not have any sequence homologies with known functional genes. We assumed that either the deletion or the transgene insertion, or both, would not cause insertional mutation. In short-term carcinogenicity testing with a genetically engineered mouse model, confirmation of the transgene or modified gene stability at each generation is one of the important factors that affect the sensitivity to carcinogenic compounds in the same way as the genetic background, age and route of administration.

    Molecular carcinogenesis 2002;34;1;1-9

  • Ecdysone-inducible expression of oncogenic Ha-Ras in NIH 3T3 cells leads to transient nuclear localization of activated extracellular signal-regulated kinase regulated by mitogen-activated protein kinase phosphatase-1.

    Plows D, Briassouli P, Owen C, Zoumpourlis V, Garrett MD and Pintzas A

    Institute for Biological Research and Biotechnology, National Hellenic Research Foundation, 116 35 Athens, Greece.

    The Ras family of GTP-binding proteins are key transducers of extracellular signals, particularly through the mitogen-activated protein kinase (MAPK) pathway. Constitutively active forms of Ras are found in a variety of tumours, suggesting an important role for this pathway in cancer. Here we report that initial cellular exposure to oncogenic Ras chronically activated the MAPK pathway in the cytoplasm, but transiently activated the same pathway in the nucleus. Nuclear-activated extracellular signal-regulated kinase (ERK) was rapidly dephosphorylated, with consequent short-term activation of the Elk-1 transcription factor and expression of the c-fos gene. Additional experiments suggested that the regulatory mechanism involved requires the calcium-dependent protein phosphotyrosine phosphatase MAPK phosphatase-1 (MKP-1). This is the first report on the ability of Ras, in the absence of growth factors, to transiently activate the MAPK pathway in the nucleus and show an involvement of MKP-1 in nuclear ERK2 regulation. In addition we show that transient activation of the MAPK pathway is sufficient to drive chronic cell-cycle progression. We conclude that, whereas the MAPK pathway is necessary to initiate cellular proliferation and transformation, the transient nature of the MAPK pathway activation suggests the involvement of additional signalling pathway(s) regulated by Ras.

    The Biochemical journal 2002;362;Pt 2;305-15

  • Regulation of choline kinase activity by Ras proteins involves Ral-GDS and PI3K.

    Ramírez de Molina A, Penalva V, Lucas L and Lacal JC

    Instituto de Investigaciones Biomédicas, CSIC, Arturo Duperier 4, 28029 Madrid, Spain.

    Ras proteins are molecular switches that control signaling pathways critical in the onset of a variety of human cancers. The signaling pathways activated by Ras proteins are those controlled by its direct effectors such as the serine-threonine protein kinase Raf-1, the exchange factor for other GTPases Ral-GDS, and the lipid kinase PI3K. As a consequence of Ras activation, a number of additional enzymes are affected, including several members of the serine-threonine intracellular proteins kinases as well as enzymes related to phospholipid metabolism regulation such as phospholipases A2 and D, and choline kinase. The precise mechanisms by which ras oncogenes impinge into these later molecules and their relevance to the onset of the carcinogenic process is still not fully understood. Here we have investigated the mechanism of regulation of choline kinase by Ras proteins and found no direct link between PLD and choline kinase activation. We provide evidence that Ras proteins regulate the activity of choline kinase through its direct effectors Ral-GDS and PI3K, while the Raf pathways seems to be not relevant in this process. The importance of Ras-dependent activation of choline kinase is discussed.

    Oncogene 2002;21;6;937-46

  • Gene expression in the developing mouse retina by EST sequencing and microarray analysis.

    Mu X, Zhao S, Pershad R, Hsieh TF, Scarpa A, Wang SW, White RA, Beremand PD, Thomas TL, Gan L and Klein WH

    Department of Biochemistry and Molecular Biology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.

    Retinal development occurs in mice between embryonic day E11.5 and post-natal day P8 as uncommitted neuroblasts assume retinal cell fates. The genetic pathways regulating retinal development are being identified but little is understood about the global networks that link these pathways together or the complexity of the expressed gene set required to form the retina. At E14.5, the retina contains mostly uncommitted neuroblasts and newly differentiated neurons. Here we report a sequence analysis of an E14.5 retinal cDNA library. To date, we have archived 15 268 ESTs and have annotated 9035, which represent 5288 genes. The fraction of singly occurring ESTs as a function of total EST accrual suggests that the total number of expressed genes in the library could approach 27 000. The 9035 ESTs were categorized by their known or putative functions. Representation of the genes involved in eye development was significantly higher in the retinal clone set compared with the NIA mouse 15K cDNA clone set. Screening with a microarray containing 864 cDNA clones using wild-type and brn-3b (-/-) retinal cDNA probes revealed a potential regulatory linkage between the transcription factor Brn-3b and expression of GAP-43, a protein associated with axon growth. The retinal EST database will be a valuable platform for gene expression profiling and a new source for gene discovery.

    Funded by: NCI NIH HHS: CA16672, P30 CA016672; NEI NIH HHS: EY11930, EY13523, R01 EY011930

    Nucleic acids research 2001;29;24;4983-93

  • p53 and H-ras mutations and microsatellite instability in renal pelvic carcinomas of NON / Shi mice treated with N-butyl-N-(4-hydroxybutyl)-nitrosamine: different genetic alteration from urinary bladder carcinoma.

    Gen H, Yamamoto S, Morimura K, Min W, Mitsuhashi M, Murai T, Mori S, Hosono M, Oohara T, Makino S, Wanibuchi H and Fukushima S

    Department of Pathology, Osaka City University Medical School, Abeno-ku, Osaka 545-8585, Japan. fukuchan@med.osaka-cu.ac.jp

    We previously reported p53 mutations to be frequent (greater than 70%), whereas both H-ras mutations and microsatellite instability (MSI) were infrequent (about 10%), in urinary bladder carcinomas (UBCs) and their metastatic foci in the N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced mouse urothelial carcinogenesis model. In the present study, an analysis of p53 and H-ras mutations as well as MSI was performed on 12 renal pelvic carcinomas (RPCs) and 8 metastatic or invading foci produced by the same experimental procedure. Histologically, 10 of the RPCs were transitional cell carcinomas and the remaining 2 were squamous cell carcinomas. p53 mutations were infrequent and only found in one primary RPC (8%), its metastatic foci and an invading lesion in another animal (in a total 2 of 12; 17%). H-ras mutations were slightly more frequent (found in 3 of 12 animals; 25%), 4 of 5 involving codon 44, GTG to GCG, not a hot-spot reported for human cancers. In two cases, H-ras mutations were confined to lung metastasis and not detectable in their primary RPCs. MSI analysis was available for 6 pairs of primary RPCs and their metastatic foci, and 4 animals (67%) had MSI at one or more microsatellite loci. Overall, the distribution of genetic alterations differed from that in UBCs produced by the same experimental protocol. The results thus suggest that different genetic pathways may participate in carcinogenesis of the upper and lower urinary tract due to BBN.

    Japanese journal of cancer research : Gann 2001;92;12;1278-83

  • Patterning the optic neuroepithelium by FGF signaling and Ras activation.

    Zhao S, Hung FC, Colvin JS, White A, Dai W, Lovicu FJ, Ornitz DM and Overbeek PA

    Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.

    During vertebrate embryogenesis, the neuroectoderm differentiates into neural tissues and also into non-neural tissues such as the choroid plexus in the brain and the retinal pigment epithelium in the eye. The molecular mechanisms that pattern neural and non-neural tissues within the neuroectoderm remain unknown. We report that FGF9 is normally expressed in the distal region of the optic vesicle that is destined to become the neural retina, suggesting a role in neural patterning in the optic neuroepithelium. Ectopic expression of FGF9 in the proximal region of the optic vesicle extends neural differentiation into the presumptive retinal pigment epithelium, resulting in a duplicate neural retina in transgenic mice. Ectopic expression of constitutively active Ras is also sufficient to convert the retinal pigment epithelium to neural retina, suggesting that Ras-mediated signaling may be involved in neural differentiation in the immature optic vesicle. The original and the duplicate neural retinae differentiate and laminate with mirror-image polarity in the absence of an RPE, suggesting that the program of neuronal differentiation in the retina is autonomously regulated. In mouse embryos lacking FGF9, the retinal pigment epithelium extends into the presumptive neural retina, indicating a role of FGF9 in defining the boundary of the neural retina.

    Funded by: NCI NIH HHS: CA60673; NEI NIH HHS: EY10448, EY10803

    Development (Cambridge, England) 2001;128;24;5051-60

  • Dermal carcinogenicity in transgenic mice: effect of vehicle on responsiveness of hemizygous Tg.AC mice to phorbol 12-myristate 13-acetate (TPA).

    Stoll RE, Furst SM, Stoltz JH, Lilly PD and Mennear JH

    Department of Toxicology and Safety Assessment, Boehringer Ingelheim Pharmaceuticals, Ridgefield, Connecticut 06877, USA. rstoll@rdg.boehringer-ingelheim.com

    The Tg.AC mouse is being evaluated for use in short-term carcinogenicity bioassays. Because the dermal test protocol necessitates dissolving test agents we determined the effects of several solvents on responsiveness of hemizygous mice to dermal applications of the classical skin tumor promoter. phorbol 12-myristate 13-acetate (TPA). Mice of both sexes received dermal applications of either acetone (negative control) or TPA in various vehicles [acetone, 100% methanol, 70% and 100% ethanol, DMSO and mixtures of acetone and ethanol (1:1), acetone and DMSO (4:1 and 1: 1). and acetone and olive oil (4:1)]. Negative control animals did not exhibit papillomas. When administered in acetone. ethanolic or methanolic vehicles TPA caused prompt and robust papillomatous responses. TPA was also tumorigenic in all nonalcoholic vehicles, except the acetone-olive oil mixture. Papilloma responses were generally delayed when TPA was applied in the nonalcoholic solvents but the distinction between TPA-dosed and negative control groups was unequivocal. These results show that choice of vehicle may affect the quantitative and qualitative nature of the response of Tg.AC mice to TPA, but 8 of 9 vehicles proved satisfactory for delivery of TPA.

    Toxicologic pathology 2001;29;5;535-40

  • Astrocyte-specific expression of activated p21-ras results in malignant astrocytoma formation in a transgenic mouse model of human gliomas.

    Ding H, Roncari L, Shannon P, Wu X, Lau N, Karaskova J, Gutmann DH, Squire JA, Nagy A and Guha A

    Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5 Canada.

    Activation of the p21-ras signaling pathway from aberrantly expressed receptors promotes the growth of malignant human astrocytomas. We developed a transgenic mouse astrocytoma model using the glial fibrillary acidic protein (GFAP) promoter to express oncogenic V(12)Ha-ras, specifically in astrocytes. The development of GFAP-immunoreactive astrocytomas was directly proportional to the level of V(12)Ha-ras transgene expression. Chimeras expressing high levels of V(12)Ha-ras in astrocytes died from multifocal malignant astrocytomas within 2 weeks, whereas those with moderate levels went to germ-line transmission. Ninety-five percent of these mice died from solitary or multifocal low- and high-grade astrocytomas within 2-6 months. These transgenic astrocytomas are pathologically similar to human astrocytomas, with a high mitotic index, nuclear pleomorphism, infiltration, necrosis, and increased vascularity. Derivative astrocytoma cells are tumorigenic upon inoculation in another host. The transgenic astrocytomas exhibit additional molecular alterations associated with human astrocytomas, including a decreased or absent expression of p16, p19, and PTEN as well as overexpression of EGFR, MDM2, and CDK4. Cytogenetic analysis revealed consistent clonal aneuploidies of chromosomal regions syntenic with comparable loci altered in human astrocytomas. Therefore, this transgenic mouse astrocytoma model recapitulates many of the molecular histopathological and growth characteristics of human malignant astrocytomas in a reproducible, germ-line-transmitted, and high-penetrance manner.

    Cancer research 2001;61;9;3826-36

  • Age-dependent skin tumorigenesis and transgene expression in the Tg.AC (v-Ha-ras) transgenic mouse.

    Battalora MS, Spalding JW, Szczesniak CJ, Cape JE, Morris RJ, Trempus CS, Bortner CD, Lee BM and Tennant RW

    Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institutes of Environmental Health Sciences, PO Box 12233, Research Triangle Park, NC 27709, USA.

    Transgenic Tg.AC (v-Ha-ras ) mice develop skin tumors in response to specific carcinogens and tumor promoters. The Tg.AC mouse carries the coding sequence of v-Ha ras, linked to a zeta-globin promoter and an SV40 polyadenylation signal sequence. The transgene confers on these mice the property of genetically initiated skin. This study examines the age-dependent sensitivity of the incidence of skin papillomas in Tg.AC mice exposed to topically applied 12-O:-tetradecanoylphorbol-13-acetate (TPA) treatment, full thickness skin wounding or UV radiation. Skin tumor incidence and multiplicity were strongly age-dependent, increasing with increasing age of the animal when first treated at 5, 10, 21 or 32 weeks of age. Furthermore, the temporal induction of transgene expression in keratinocytes isolated from TPA-treated mouse skin was also influenced by the age of the mice. Transgene expression was seen as early as 14 days after the start of TPA treatment in mice that were 10-32 weeks of age, but was not detected in similarly treated 5-week old mice. When isolated keratinocytes were fractionated by density gradient centrifugation the highest transgene expression was found in the denser basal keratinocytes. Transgene expression could be detected in the denser keratinocyte fraction as early as 9 days from start of TPA treatment in 32-week old mice. Using flow cytometry, a positive correlation was observed between expression of the v-Ha-ras transgene and enriched expression of the cell surface protein beta1-integrin, a putative marker of epidermal stem cells. This result suggests that, in the Tg.AC mouse, an age-dependent sensitivity to tumor promotion and the correlated induction of transgene expression are related to changes in cellular development in the follicular compartment of the skin.

    Funded by: NCI NIH HHS: CA54293

    Carcinogenesis 2001;22;4;651-9

  • Effect of bacterial metabolism in the intestine on colorectal tumors induced by 1,2-dimethylhydrazine in transgenic mice harboring human prototype c-Ha-ras genes.

    Ohno K, Narushima S, Takeuchi S, Itoh K, Itoh T, Hioki K and Nomura T

    Laboratory of Veterinary Public Health, Graduate School of Agriculture and Life Science, The University of Tokyo, Japan.

    The number of colorectal tumors per mouse induced by 1,2-dimethylhydrazine in transgenic (Tg) mice carrying human c-Ha-ras genes was significantly reduced by ingestion of apple pectin (AP) or a culture condensate of Bifidobacterium longum(MB) compared with a control diet and non-Tg mice. However, there were no differences in the composition of fecal flora, water content, beta-glucuronidase and beta-glucosidase activities, and concentrations of organic acids and putrefactive products in the feces between the AP or MB diet and the control diet, or between the Tg mice and non-Tg mice. The concentration of secondary bile acids in the MB diet group was higher than that in the control group. These results suggested that there was no relationship between prevention of colorectal tumors in Tg mice and the AP or MB diet, or improvement of the intestinal environment due to these functional foods.

    Journal of experimental & clinical cancer research : CR 2001;20;1;51-6

  • Targeted genomic disruption of H-ras and N-ras, individually or in combination, reveals the dispensability of both loci for mouse growth and development.

    Esteban LM, Vicario-Abejón C, Fernández-Salguero P, Fernández-Medarde A, Swaminathan N, Yienger K, Lopez E, Malumbres M, McKay R, Ward JM, Pellicer A and Santos E

    Centro de Investigación del Cáncer, IBMCC, CSIC-USAL, University of Salamanca, Salamanca, Spain.

    Mammalian cells harbor three highly homologous and widely expressed members of the ras family (H-ras, N-ras, and K-ras), but it remains unclear whether they play specific or overlapping cellular roles. To gain insight into such functional roles, here we generated and analyzed H-ras null mutant mice, which were then also bred with N-ras knockout animals to ascertain the viability and properties of potential double null mutations in both loci. Mating among heterozygous H-ras(+/-) mice produced H-ras(-/-) offspring with a normal Mendelian pattern of inheritance, indicating that the loss of H-ras did not interfere with embryonic and fetal viability in the uterus. Homozygous mutant H-ras(-/-) mice reached sexual maturity at the same age as their littermates, and both males and females were fertile. Characterization of lymphocyte subsets in the spleen and thymus showed no significant differences between wild-type and H-ras(-/-) mice. Analysis of neuronal markers in the brains of knockout and wild-type H-ras mice showed that disruption of this locus did not impair or alter neuronal development. Breeding between our H-ras mutant animals and previously available N-ras null mutants gave rise to viable double knockout (H-ras(-/-)/N-ras(-/-)) offspring expressing only K-ras genes which grew normally, were fertile, and did not show any obvious phenotype. Interestingly, however, lower-than-expected numbers of adult, double knockout animals were consistently obtained in Mendelian crosses between heterozygous N-ras/H-ras mice. Our results indicate that, as for N-ras, H-ras gene function is dispensable for normal mouse development, growth, fertility, and neuronal development. Additionally, of the three ras genes, K-ras appears to be not only essential but also sufficient for normal mouse development.

    Molecular and cellular biology 2001;21;5;1444-52

  • Induction of drug metabolism-related enzymes by methylcholanthrene and phenobarbital in transgenic mice carrying human prototype c-Ha-ras gene and their wild type littermates.

    Ohnishi Y, Arai T, Koshirakawa M, Horii N, Nakajo S, Urano K, Usui T, Tamaoki N and Ueyama Y

    Central Institute for Experimental Animals, 1430 Nogawa, Miyamae-ku, Kawasaki-shi 216-0001, Japan.

    Transgenic mice hemizygously carrying human c-Ha-ras proto-oncogene, Tg-rasH2 show very sensitive and facilitated carcinogenicity to various carcinogens. In this study, activities of certain enzymes related to drug metabolism and energy metabolism were measured in microsome and cytosol fractions of livers of Tg-rasH2 mice and their wild type littermates with both sexes treated with 3-methylcholanthrene (MC) and phenobarbital (PB). Aminopyrine N-demethylase activities increased significantly in livers of all mice treated with PB. MC and PB treatments induced significant increases in activities of UDP-glucuronosyltransferase and S-adenosyl homocysteinase compared to those in the non-treated groups in microsome fractions from all mice. In cytosol fractions of livers of all mice, glutathione S-transferase activity was significantly induced in the PB treated groups. There were no significant differences in activities of lactate dehydrogenase, glucose 6-phosphate dehydrogenase, pyruvate kinase and glucose 6-phosphatase related to energy metabolism in livers and kidneys among all mice. Tg-rasH2 mice showed stable activities of enzymes related to drug detoxication and energy metabolism similar to those of non-transgenic mice. These results suggest that the human c-Ha-ras transgene may not affect drug metabolism-related enzymes, and the facilitated carcinogenic response in the Tg-rasH2 mouse is not due to these enzymatic disorders.

    Experimental animals 2001;50;1;33-9

  • The rasH2 transgenic mouse: nature of the model and mechanistic studies on tumorigenesis.

    Tamaoki N

    Tokai University School of Medicine, Central Institute for Experimental Animals, Miyamae, Kawasaki, Japan.

    The rasH2 mouse is a hemizygous transgenic mouse carrying the c-Ha-ras oncogene and that gene's promotor/enhancer within the genetic background of a BALB/cByJ x C57BL/6J F1 mouse. Approximately 3 copies of the transgene are integrated in a tandem array into chromosome number 15. The transgene is transmitted stably without point mutation in hot spots and is expressed in all tissues over 20 backcross generations. The homozygous c-Ha-ras genotype is lethal. Hemizygotes are selected by polymerase chain reaction (PCR) analysis of tail tips after birth. Spontaneous tumors in hemizygous transgenic mice are rare until 6 months of age. The observed rasH2 tumor spectrum, including lung adenoma/adenocarcinoma, forestomach and skin papillomas, Harderian gland adenoma, liver proliferative lesions, splenic hemangioma/sarcoma, and lymphoma is consistent with the BALB/c and C57BL/6 background. In the rasH2 mouse, point mutations of the transgene induced by genotoxins are reported frequently but not in all tumors. Elevated levels of transgene expression were detected in all genotoxin-induced tumors in the rasH2. Increased transgene expression was independent of the mutation rate in transgenic and endogenous ras genes. These observations suggest that the overexpression of transgenic c-Ha-ras is responsible for accelerated tumor development.

    Toxicologic pathology 2001;29 Suppl;81-9

  • The Tg.AC (v-Ha-ras) transgenic mouse: nature of the model.

    Tennant RW, Stasiewicz S, Eastin WC, Mennear JH and Spalding JW

    National Institute of Environmental Health Sciences, Laboratory of Environmental Carcinogenesis and Mutagenesis, Research Triangle Park, North Carolina 27709, USA. tennant@niehs.nih.gov

    The Tg.AC (v-Ha-ras) transgenic mouse model provides a reporter phenotype of skin papillomas in response to either genotoxic or nongenotoxic carcinogens. In common with the conventional bioassay, the Tg.AC model responds to known human carcinogens and does not respond to noncarcinogens. It also does not respond to most chemicals that are positive in conventional bioassays principally at sites of high spontaneous tumor incidence. The mechanism of response of the Tg.AC model is related to the structure and genomic position of the transgene and the induction of transgene expression through specific mediated interactions between the chemicals and target cells in the skin.

    Toxicologic pathology 2001;29 Suppl;51-9

  • Transgenic activation of Ras in neurons promotes hypertrophy and protects from lesion-induced degeneration.

    Heumann R, Goemans C, Bartsch D, Lingenhöhl K, Waldmeier PC, Hengerer B, Allegrini PR, Schellander K, Wagner EF, Arendt T, Kamdem RH, Obst-Pernberg K, Narz F, Wahle P and Berns H

    Ruhr-University of Bochum, Molecular Neurobiochemistry, Germany. rolf.heumann@ruhr-uni-bochum.de

    Ras is a universal eukaryotic intracellular protein integrating extracellular signals from multiple receptor types. To investigate its role in the adult central nervous system, constitutively activated V12-Ha-Ras was expressed selectively in neurons of transgenic mice via a synapsin promoter. Ras-transgene protein expression increased postnatally, reaching a four- to fivefold elevation at day 40 and persisting at this level, thereafter. Neuronal Ras was constitutively active and a corresponding activating phosphorylation of mitogen-activated kinase was observed, but there were no changes in the activity of phosphoinositide 3-kinase, the phosphorylation of its target kinase Akt/PKB, or expression of the anti-apoptotic proteins Bcl-2 or Bcl-X(L). Neuronal Ras activation did not alter the total number of neurons, but induced cell soma hypertrophy, which resulted in a 14.5% increase of total brain volume. Choline acetyltransferase and tyrosine hydroxylase activities were increased, as well as neuropeptide Y expression. Degeneration of motorneurons was completely prevented after facial nerve lesion in Ras-transgenic mice. Furthermore, neurotoxin-induced degeneration of dopaminergic substantia nigra neurons and their striatal projections was greatly attenuated. Thus, the Ras signaling pathway mimics neurotrophic effects and triggers neuroprotective mechanisms in adult mice. Neuronal Ras activation might become a tool to stabilize donor neurons for neural transplantation and to protect neuronal populations in neurodegenerative diseases.

    The Journal of cell biology 2000;151;7;1537-48

  • Both (+/-)syn- and (+/-)anti-7,12-dimethylbenz[a]anthracene-3,4-diol-1,2-epoxides initiate tumors in mouse skin that possess -CAA- to -CTA- mutations at Codon 61 of c-H-ras.

    Tang MS, Vulimiri SV, Viaje A, Chen JX, Bilolikar DS, Morris RJ, Harvey RG, Slaga TJ and DiGiovanni J

    Department of Environmental Medicine, New York University School of Medicine, Tuxedo 10987, USA. tang@env.med.nyu.edu

    We have determined the tumor-initiating activity of (+/-)syn- and (+/-)anti-7,12-dimethylbenz[a]anthracene-3,4-diol-1,2-epoxide (syn- and anti-DMBADE), the two metabolically formed bay-region diol epoxides of DMBA, and we have also analyzed mutations in the H-ras gene from tumors induced by these compounds. Using a two-stage, initiation-promotion protocol for tumorigenesis in mouse skin, we have found that both syn- and anti-DMBADE are active tumor initiators, and that the occurrence of papillomas is carcinogen dose dependent. All of the papillomas induced by syn-DMBADE (a total of 40 mice), 96% of those induced by anti-DMBADE (a total of 25 mice), and 94% of those induced by DMBA (a total of 16 mice) possessed a -CAA- to -CTA- mutation at codon 61 of H-ras. No mutations in codons 12 or 13 were detected in any tumor. Topical application of syn- and anti-DMBADE produced stable adducts in mouse epidermal DNA, most of which comigrated with stable DNA adducts formed after topical application of DMBA. Further analysis of the data showed that levels of the major syn- and anti-DMBADE-deoxyadenosine adducts formed after topical application of DMBA are sufficient to account for the tumor-initiating activity of this carcinogen on mouse skin. Previously, we showed that both the syn- and anti-DMBADE bind to the adenine (A182) at codon 61 of H-ras. Collectively, these results indicate that the adenine adducts induced by both bay-region diol epoxides of DMBA lead to the mutation at codon 61 of H-ras and, consequently, initiate tumorigenesis in mouse skin.

    Funded by: NCI NIH HHS: CA36979; NIEHS NIH HHS: ES03124, ES08389; ...

    Cancer research 2000;60;20;5688-95

  • A novel RalGEF-like protein, RGL3, as a candidate effector for rit and Ras.

    Shao H and Andres DA

    Department of Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536-0230, USA.

    The small GTPase Rit is a close relative of Ras, and constitutively active Rit can induce oncogenic transformation. Although the effector loops of Rit and Ras are highly related, Rit fails to interact with the majority of the known Ras candidate effector proteins, suggesting that novel cellular targets may be responsible for Rit transforming activity. To gain insight into the cellular function of Rit, we searched for Rit-binding proteins by yeast two-hybrid screening. We identified the C-terminal Rit/Ras interaction domain of a protein we have designated RGL3 (Ral GEF-like 3) that shares 35% sequence identity with the known Ral guanine nucleotide exchange factors (RalGEFs). RGL3, through a C-terminal 99-amino acid domain, interacted in a GTP- and effector loop-dependent manner with Rit and Ras. Importantly, RGL3 exhibited guanine nucleotide exchange activity toward the small GTPase Ral that was stimulated in vivo by the expression of either activated Rit or Ras. These data suggest that RGL3 functions as an exchange factor for Ral and may serve as a downstream effector for both Rit and Ras.

    Funded by: NEI NIH HHS: EY11231

    The Journal of biological chemistry 2000;275;35;26914-24

  • Mammary tumor development in MMTV-c-myc/MMTV-v-Ha-ras transgenic mice is unaffected by osteopontin deficiency.

    Feng F and Rittling SR

    Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, USA.

    Transgenic mice expressing c-myc and v-Ha-ras specifically in the mammary gland under the control of the mammary specific promoter MMTV develop unifocal mammary tumors with a half time of about 46 days, and these tumors express high levels of osteopontin mRNA and protein. In order to evaluate the requirement for osteopontin expression by these tumors, we have crossed transgenic mice expressing these two oncogenes with mice with a targeted disruption of the osteopontin gene. Littermates expressing both myc and ras, and with either wild-type or disrupted OPN alleles were evaluated for tumor incidence and growth rate. Both of these parameters were found to be unaffected by a lack of osteopontin in the whole animal. Ras and myc expression level, measured at the level of mRNA, was not different in tumors of the two genotypes. Macrophage accumulation, while extremely variable among different tumors, did not correlate with the OPN status of the animals. Expression of the related gene BSP was not detected in any of the tumors, and was similar in bones of wildtype and OPN -/- mice. Similarly, the vitronectin gene was expressed at very low levels in tumors of either genotype. These results indicate that despite its high level of expression, OPN is either not required for mammary primary tumor formation and growth in this system, or can be replaced by molecules other than BSP and vitronectin in mice that totally lack osteopontin.

    Funded by: NCI NIH HHS: R01 CA72740; PHS HHS: NJCCR 96031

    Breast cancer research and treatment 2000;63;1;71-9

  • Genome-wide expression profiling of mid-gestation placenta and embryo using a 15,000 mouse developmental cDNA microarray.

    Tanaka TS, Jaradat SA, Lim MK, Kargul GJ, Wang X, Grahovac MJ, Pantano S, Sano Y, Piao Y, Nagaraja R, Doi H, Wood WH, Becker KG and Ko MS

    Laboratory of Genetics and DNA Array Unit, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224-6820, USA.

    cDNA microarray technology has been increasingly used to monitor global gene expression patterns in various tissues and cell types. However, applications to mammalian development have been hampered by the lack of appropriate cDNA collections, particularly for early developmental stages. To overcome this problem, a PCR-based cDNA library construction method was used to derive 52,374 expressed sequence tags from pre- and peri-implantation embryos, embryonic day (E) 12.5 female gonad/mesonephros, and newborn ovary. From these cDNA collections, a microarray representing 15,264 unique genes (78% novel and 22% known) was assembled. In initial applications, the divergence of placental and embryonic gene expression profiles was assessed. At stage E12.5 of development, based on triplicate experiments, 720 genes (6.5%) displayed statistically significant differences in expression between placenta and embryo. Among 289 more highly expressed in placenta, 61 placenta-specific genes encoded, for example, a novel prolactin-like protein. The number of genes highly expressed (and frequently specific) for placenta has thereby been increased 5-fold over the total previously reported, illustrating the potential of the microarrays for tissue-specific gene discovery and analysis of mammalian developmental programs.

    Proceedings of the National Academy of Sciences of the United States of America 2000;97;16;9127-32

  • Targeted deletion of the H-ras gene decreases tumor formation in mouse skin carcinogenesis.

    Ise K, Nakamura K, Nakao K, Shimizu S, Harada H, Ichise T, Miyoshi J, Gondo Y, Ishikawa T, Aiba A and Katsuki M

    Department of Cell Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.

    To clarify the role of the H-Ras in vivo, we generated H-ras null mutant mice by gene targeting. In spite of the importance of the Ras in cell proliferation and differentiation, H-ras null mutant mice grew normally and were fertile. The oldest H-ras mutant mice grew to be more than 30 months old. We used the H-ras deficient mice to study the importance of the H-ras and other ras genes in the development of skin tumors induced by initiation with 7, 12-dimethylbenz(a)anthracene (DMBA) followed by promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA). We showed that H-ras null mutant mice develop approximately six times less papillomas compared with wild-type littermates after 20 weeks of TPA treatment. While all papillomas examined (17 out of 17) in wild-type mice have mutations of H-ras at codon 61, 13 (62%) out of 21 papillomas in H-ras null mutant mice have mutations of K-ras gene at codon 12, 13, or 61 and another eight (38%) papillomas have no mutations in these codons of K-ras or N-ras genes. This suggests that the activation of H-ras gene is critical in the wild-type mice, but the activation of K-ras gene can replace the H-ras activation in the initiation step of skin tumor development in the H-ras deficient mice. Oncogene (2000).

    Oncogene 2000;19;26;2951-6

  • Hepatic drug metabolizing enzymes induced by clofibrate in rasH2 mice.

    Katsutani N, Sekido T, Aoki T and Sagami F

    Department of Developmental Safety Assessment Research, Eisai Company, Gifu, Japan. n-katsutani@hhc.eisai.co.jp

    Hepatic drug metabolizing enzyme activities were determined, after treatment with clofibrate, in transgenic mice carrying human c-Ha-ras (rasH2 mice). Changes in the drug metabolizing enzyme activities in these mice by gene integration were also evaluated. Male and female rasH2 mice (Tg) and the litter mates not carrying the gene (non-Tg) received orally 500 mg/kg of clofibrate or the vehicle for 12 consecutive days. Liver homogenate and microsomes were prepared and the contents and activities of cytochrome P450 (CYP), cytochrome b5 content and enzyme activities related to peroxisome proliferation were determined. Relative liver weights, CYP4A and activities of catalase and carnitine palmitoyl transferase increased to the same extent in Tg and non-Tg mice treated with clofibrate. In Tg and non-Tg groups that received vehicle, contents and activities of CYP and cytchrome b5 contents were comparable. It was concluded that gene integration did not alter drug metabolizing enzymes and responses to clofibrate.

    Toxicology letters 2000;115;3;223-9

  • Regulation of long-term potentiation by H-Ras through NMDA receptor phosphorylation.

    Manabe T, Aiba A, Yamada A, Ichise T, Sakagami H, Kondo H and Katsuki M

    Department of Neurophysiology, Faculty of Medicine, University of Tokyo, Tokyo 113-0033, Japan.

    The proto-oncogene ras plays a critical role in cell proliferation and differentiation. However, ras genes are abundantly expressed in the adult CNS, although neuronal cells normally do not proliferate. Recently, several lines of evidence implicated the involvement of Ras signaling pathway in synaptic plasticity. To explore the role of the Ras proteins in the CNS, we generated knock-out mice lacking the H-ras gene and then used them to study the roles of Ras in synaptic transmission and plasticity. An investigation of protein phosphorylation and synaptic transmission in H-ras null mutant mice has shown that the NMDA receptor is a final target molecule of the Ras protein pathway in the CNS. In the H-ras null mutant hippocampus, the tyrosine phosphorylation of NR2A (epsilon1) and NR2B (epsilon2) subunits of NMDA receptors is increased, and, correspondingly, NMDA synaptic responses are selectively enhanced. In addition, long-term potentiation is markedly enhanced in mutant mice, most likely because of a selective enhancement of NMDA synaptic responses. Therefore, although Ras proteins have been implicated in cell proliferation and differentiation, the regulation of activity-dependent synaptic plasticity in the adult animals by downregulation of the phosphorylation of the NMDA receptor may be another major and pivotal role for H-Ras protein.

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2000;20;7;2504-11

  • Neurofibromin negatively regulates neurotrophin signaling through p21ras in embryonic sensory neurons.

    Vogel KS, El-Afandi M and Parada LF

    Center for Developmental Biology, University of Texas Southwestern Medical Center, Dallas 75235-9133, USA. kvogel@lsumc.edu

    Embryonic sensory and sympathetic neurons that lack neurofibromin, the protein product of the neurofibromatosis type 1 (Nfl) gene, survive and extend neurites in the absence of neurotrophins. To determine whether neurofibromin negatively regulates neurotrophin signaling through its interaction with p21ras, we used Fab antibody fragments to block Ras function in DRG, trigeminal, nodose, and SCG neurons isolated from Nfl(-/-) and wild-type mouse embryos. We show that introduction of anti-Ras Fab fragments significantly reduces the ability of neurofibromin-deficient neurons to survive in the absence of neurotrophins. Moreover, addition of H-ras protein enhances the survival of Nfl(-/-), but not wild-type, DRG neurons. Our results are consistent with a major role for neurofibromin in modulating Trk signaling through p21ras during neuronal development.

    Funded by: NIAMS NIH HHS: P30AR41940; NINDS NIH HHS: R01 NS33199

    Molecular and cellular neurosciences 2000;15;4;398-407

  • Small GTPases and cell cycle regulation.

    Marshall CJ

    CRC Centre for Cell and Molecular Biology, Institute of Cancer Research, London, UK.

    Biochemical Society transactions 1999;27;4;363-70

  • Disruption of the mouse Rce1 gene results in defective Ras processing and mislocalization of Ras within cells.

    Kim E, Ambroziak P, Otto JC, Taylor B, Ashby M, Shannon K, Casey PJ and Young SG

    Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94141-9100, USA. ekim@gladstone.ucsf.edu

    Little is known about the enzyme(s) required for the endoproteolytic processing of mammalian Ras proteins. We identified a mouse gene (designated Rce1) that shares sequence homology with a yeast gene (RCE1) implicated in the proteolytic processing of Ras2p. To define the role of Rce1 in mammalian Ras processing, we generated and analyzed Rce1-deficient mice. Rce1 deficiency was lethal late in embryonic development (after embryonic day 15.5). Multiple lines of evidence revealed that Rce1-deficient embryos and cells lacked the ability to endoproteolytically process Ras proteins. First, Ras proteins from Rce1-deficient cells migrated more slowly on SDS-polyacrylamide gels than Ras proteins from wild-type embryos and fibroblasts. Second, metabolic labeling of Rce1-deficient cells revealed that the Ras proteins were not carboxymethylated. Finally, membranes from Rce1-deficient fibroblasts lacked the capacity to proteolytically process farnesylated Ha-Ras, N-Ras, and Ki-Ras or geranylgeranylated Ki-Ras. The processing of two other prenylated proteins, the farnesylated Ggamma1 subunit of transducin and geranylgeranylated Rap1B, was also blocked. The absence of endoproteolytic processing and carboxymethylation caused Ras proteins to be mislocalized within cells. These studies indicate that Rce1 is responsible for the endoproteolytic processing of the Ras proteins in mammals and suggest a broad role for this gene in processing other prenylated CAAX proteins.

    Funded by: NHLBI NIH HHS: HL-41633, HL-47660; NIA NIH HHS: AG-15451; ...

    The Journal of biological chemistry 1999;274;13;8383-90

  • Genetic events and the role of TGF beta in epithelial tumour progression.

    Akhurst RJ and Balmain A

    Onyx Pharmaceuticals, Richmond, CA 94806, USA.

    The mouse skin model of chemical carcinogenesis has been very well characterized with respect to epigenetic changes, which occur during tumour cell initiation, promotion and progression. The use of transgenic and gene knock-out mice has contributed greatly to knowledge in this area. The H-ras genetic locus has been shown to undergo multiple genetic changes, including mutagenic activation, amplification of the mutant gene, and loss of the normal allele. These different genetic events lead to thresholds of ras activity which contribute to different stages along the pathway to neoplasia. The genetic and epigenetic events which lead to tumour invasion and metastasis have been less well characterized than studies on tumour initiation and promotion, despite the fact that it is metastases which ultimately kill the animal/patient. In the mouse skin model, loss of p53 contributes to malignant conversion. Gene deletion of the INK4 locus is associated with transformation to a highly invasive spindle cell tumor phenotype. This spindle cell transformation can also be induced in vitro or in vivo by TGF beta 1, possible by synergizing with mutant H-ras. TGF beta can have both positive and negative effects on tumourigenesis, acting early as a tumour suppresser, but later as a stimulator of tumour invasion. It is this latter effect which may be clinically more significant, since many human tumours overexpress TGF beta, yet the majority still retain the intracellular signaling systems necessary for the cell to respond to this growth factor.

    The Journal of pathology 1999;187;1;82-90

  • Insights into cancer from transgenic mouse models.

    Macleod KF and Jacks T

    Department of Molecular and Cellular Pathology, University of Dundee, Ninewells Hospital, Scotland, U.K. K.F.MACLEOD@dundee.ac.uk

    The generation of mice designed to overexpress activated forms of oncogenes or carrying targeted mutations in tumour suppressor genes, has allowed scientists to causally link the function of these genes with specific tumour processes, such as proliferation, apoptosis, angiogenesis or metastasis. In addition, these mice have been interbred to assess the extent of cooperativity between different genetic lesions in disease progression, leading to a greater understanding of the multi-stage nature of tumourigenesis. The effect of genetic mutations is often influenced by the genetic background of the mouse and by analysing strain-dependent phenotypes, modifier loci have been identified. Although genetic mutations in mouse and humans do not always lead to the same tumour spectrum, the underlying molecular mechanisms are frequently relevant to both species. Furthermore, new technical approaches creating conditional mouse mutants which develop tumours in a tissue-specific manner, will allow the effect of mutation of certain genes to be studied in specific tissues, free from the fatal effects of the mutation in other clinically less relevant tissues. Several exising mouse strains have already been used to develop and test new therapies and conditional mutagenesis will undoubtedly increase the potential use of transgenic mice in understanding and treating cancer.

    The Journal of pathology 1999;187;1;43-60

  • p21 ras and phosphatidylinositol-3 kinase are required for survival of wild-type and NF1 mutant sensory neurons.

    Klesse LJ and Parada LF

    Center for Developmental Biology, University of Texas, Southwestern Medical Center, Dallas, Texas 75235-9133, USA.

    Nerve growth factor (NGF) is a required differentiation and survival factor for sympathetic and a majority of neural crest-derived sensory neurons in the developing vertebrate peripheral nervous system. Although much is known about the function of NGF, the intracellular signaling cascade that it uses continues to be a subject of intense study. p21 ras signaling is considered necessary for sensory neuron survival. How additional intermediates downstream or in parallel may function has not been fully understood yet. Two intracellular signaling cascades, extra cellular regulated kinase (erk) and phosphatidylinositol-3 (PI 3) kinase, transduce NGF signaling in the pheochromocytoma cell line PC12. To elucidate the role these cascades play in survival and differentiation, we used a combination of recombinant adenoviruses and chemical inhibitors to perturb these pathways in sensory neurons from wild-type mice and mice deficient for neurofibromin in which the survival and differentiation pathway is constitutively active. We demonstrate that ras activity is both necessary and sufficient for the survival of embryonic sensory neurons. Downstream of ras, however, the erk cascade is neither required nor sufficient for neuron survival or overall differentiation. Instead, the activity of PI 3 kinase is necessary for the survival of the wild-type and neurofibromin-deficient neurons. Therefore, we conclude that in sensory neurons, NGF acts via a signaling pathway, which includes both ras and PI 3 kinase.

    Funded by: NINDS NIH HHS: R01-NS34296

    The Journal of neuroscience : the official journal of the Society for Neuroscience 1998;18;24;10420-8

  • Alterations of oncogenes, tumor suppressor genes and growth factors in hepatocellular carcinoma: with relation to tumor size and invasiveness.

    Tang Z, Qin L, Wang X, Zhou G, Liao Y, Weng Y, Jiang X, Lin Z, Liu K and Ye S

    Liver Cancer Institute, Shanghai Medical University, China.

    Objective: To make a better understanding of the molecular mechanisms involved in recurrence and metastasis of the hepatocellular carcinoma (HCC), some invasion related oncogenes, and growth factors have been investigated.

    Methods: The studies were separately carried out, the results of which were summarized in this article with relation to tumor size and invasiveness of HCC.

    Results: The aberration rates of p53 and CDKN2 in HCC were 45.9% and 36.4% respectively, which were higher in invasive HCC compared with non-invasive HCC. H-ras expression was positive in 29.3% of HCC, which was associated with recurrence and extrahepatic metastasis of HCC. Intralesional injection of H-ras antisense gene markedly inhibited the tumor growth and metastasis of HCC in nude mice. The positive rates of transforming growth factor (TGF)-alpha, epidermal growth factor receptor (EGFR) and c-erbB-2 were 45.7%, 47.1% and 92.3% respectively. The expression of EGFR was closely related to TGF-alpha, which was related to HCC recurrence. But no obvious difference of TGF-alpha or c-erbB-2 expression was found between HCC with and without recurrence, or with and without extrahepatic metastasis. Expression of nm23/tissue inhibitor of metalloproteinase (TIMP)-2 was positively associated with the prognosis of HCC patients (Log-rank, P < 0.001). The alterative rates of above-mentioned genes and growth factors in small HCC were slightly lower than that in large ones, but no significant difference was shown except the p53 mutation.

    Conclusions: The p53/CDKN2 mutation, over-expression of H-ras/EGFR, were associated with the invasiveness and recurrence of HCC. H-ras antisense gene might be of potential implication in the control of HCC recurrence and metastasis. Expression of nm23/TIMP-2 was closely related to the prognosis of HCC patients. Biological characteristics remained critical points to the prognosis even in small HCC.

    Chinese medical journal 1998;111;4;313-8

  • Identification of Nore1 as a potential Ras effector.

    Vavvas D, Li X, Avruch J and Zhang XF

    The Diabetes Unit and Medical Services and the Department of Medicine, Harvard Medical School, Massachusetts General Hospital East, Charlestown, Massachusetts 02129, USA.

    The small GTP-binding protein Ras is pivotal in transmitting growth and differentiation signals downstream of cell surface receptors. Many observations have indicated that Ras transmits signals from cell surface receptors into multiple pathways via direct interaction with different effectors in mammalian cells. We have identified a novel potential Ras effector or target named Nore1. Nore1 has no significant sequence similarity to known mammalian proteins and lacks an identifiable catalytic domain, but contains sequence motifs that predict DAG_PE binding and SH3 domain binding. We show that Nore1 directly interacts with Ras in vitro in a GTP-dependent manner, and the interaction requires an intact Ras effector domain. Nore1 becomes associated with Ras in situ following activation of epidermal growth factor receptor in COS-7 and in KB cells.

    Funded by: NIGMS NIH HHS: GM51281

    The Journal of biological chemistry 1998;273;10;5439-42

  • K-ras is an essential gene in the mouse with partial functional overlap with N-ras.

    Johnson L, Greenbaum D, Cichowski K, Mercer K, Murphy E, Schmitt E, Bronson RT, Umanoff H, Edelmann W, Kucherlapati R and Jacks T

    Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.

    Mammalian ras genes are thought to be critical in the regulation of cellular proliferation and differentiation and are mutated in approximately 30% of all human tumors. However, N-ras and H-ras are nonessential for mouse development. To characterize the normal role of K-ras in growth and development, we have mutated it by gene targeting in the mouse. On an inbred genetic background, embryos homozygous for this mutation die between 12 and 14 days of gestation, with fetal liver defects and evidence of anemia. Thus, K-ras is the only member of the ras gene family essential for mouse embryogenesis. We have also investigated the effect of multiple mutations within the ras gene family. Most animals lacking N-ras function and heterozygous for the K-ras mutation exhibit abnormal hematopoietic development and die between days 10 and 12 of embryogenesis. Thus, partial functional overlap appears to occur within the ras gene family, but K-ras provides a unique and essential function.

    Genes & development 1997;11;19;2468-81

  • 14-3-3 zeta negatively regulates raf-1 activity by interactions with the Raf-1 cysteine-rich domain.

    Clark GJ, Drugan JK, Rossman KL, Carpenter JW, Rogers-Graham K, Fu H, Der CJ and Campbell SL

    Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA.

    Although Raf-1 is a critical effector of Ras signaling and transformation, the mechanism by which Ras promotes Raf-1 activation is complex and remains poorly understood. We recently reported that Ras interaction with the Raf-1 cysteine-rich domain (Raf-CRD, residues 139-184) may be required for Raf-1 activation. The Raf-CRD is located in the NH2-terminal negative regulatory domain of Raf-1 and is highly homologous to cysteine-rich domains found in protein kinase C family members. Recent studies indicate that the structural integrity of the Raf-CRD is also critical for Raf-1 interaction with 14-3-3 proteins. However, whether 14-3-3 proteins interact directly with the Raf-CRD and how this interaction may mediate Raf-1 function has not been determined. In the present study, we demonstrate that 14-3-3 zeta binds directly to the isolated Raf-CRD. Moreover, mutation of Raf-1 residues 143-145 impairs binding of 14-3-3, but not Ras, to the Raf-CRD. Introduction of mutations that impair 14-3-3 binding resulted in full-length Raf-1 mutants with enhanced transforming activity. Thus, 14-3-3 interaction with the Raf-CRD may serve in negative regulation of Raf-1 function by facilitating dissociation of 14-3-3 from the NH2 terminus of Raf-1 to promote subsequent events necessary for full activation of Raf-1.

    Funded by: NCI NIH HHS: CA42978, CA64569, CA70308; ...

    The Journal of biological chemistry 1997;272;34;20990-3

  • Protein binding and signaling properties of RIN1 suggest a unique effector function.

    Han L, Wong D, Dhaka A, Afar D, White M, Xie W, Herschman H, Witte O and Colicelli J

    Department of Biological Chemistry, Molecular Genetics, and Immunology, University of California, Los Angeles, School of Medicine, Los Angeles, CA 90095, USA.

    Human RIN1 was first characterized as a RAS binding protein based on the properties of its carboxyl-terminal domain. We now show that full-length RIN1 interacts with activated RAS in mammalian cells and defines a minimum region of 434 aa required for efficient RAS binding. RIN1 interacts with the "effector domain" of RAS and employs some RAS determinants that are common to, and others that are distinct from, those required for the binding of RAF1, a known RAS effector. The same domain of RIN1 that binds RAS also interacts with 14-3-3 proteins, extending the similarity between RIN1 and other RAS effectors. When expressed in mammalian cells, the RAS binding domain of RIN1 can act as a dominant negative signal transduction blocker. The amino-terminal domain of RIN1 contains a proline-rich sequence similar to consensus Src homology 3 (SH3) binding regions. This RIN1 sequence shows preferential binding to the ABL-SH3 domain in vitro. Moreover, the amino-terminal domain of RIN1 directly associates with, and is tyrosine phosphorylated by, c-ABL. In addition, RIN1 encodes a functional SH2 domain that has the potential to activate downstream signals. These data suggest that RIN1 is able to mediate multiple signals. A differential pattern of expression and alternate splicing indicate several levels of RIN1 regulation.

    Funded by: NCI NIH HHS: CA53867, CA56301, R01 CA056301, R01 CA071443; NIGMS NIH HHS: GM24787

    Proceedings of the National Academy of Sciences of the United States of America 1997;94;10;4954-9

  • Induction of murine CD5 expression by v-H-ras.

    Weichert TR and Schwartz RC

    Department of Microbiology, Michigan State University, East Lansing 48824-1101, USA.

    The murine CD5 surface antigen is a frequent marker on B-lineage cell lines produced from bone marrow infected with retroviruses expressing v-H-ras. Since CD5+ B cells cannot be detected in adult murine bone marrow, either the viral targets of transformation are a minor contaminating population of CD5+ B-lineage cells or the v-H-ras oncogene is inducing the expression of CD5 on B-lineage cells not previously expressing this marker. We have found that v-H-ras can induce the expression of CD5 on two CD5+ pre-B-cell lines established from murine bone marrow. This induction correlates with increased steady-state levels of CD5 mRNA. These results present the possibility that CD5 expression may be modulated by specific signalling as well as early lineage commitment.

    Funded by: NCI NIH HHS: CA45360

    Immunology 1997;90;1;30-7

  • Targeted oncogenesis in the thyroid of transgenic mice.

    Feunteun J, Michiels F, Rochefort P, Caillou B, Talbot M, Fournes B, Mercken L, Schlumberger M and Monier R

    Laboratoire de Génétique oncologique, CNRS URA 1967, Villejuif, France.

    We have developed mouse models for tumors affecting the epithelial cellular compartment of the thyroid which has been targeted using the bovine thyroglobulin (bTg) promoter. Transgenic mice expressing the human activated c-Ha-Ras gene developed papillary thyroid carcinomas demonstrating the oncogenic potential of activated Ras gene in the thyroid gland. Transgenic mice express the mutant form of the alpha subunit of the adenylate cyclase-coupled G alpha s with mutations at codon 201 (R201H). The expression of this mutant transgene is not by itself sufficient to produce benign tumors or even hyperplasia, but the transgenic mice have inherited a predisposition to develop thyroid adenomas.

    Hormone research 1997;47;4-6;137-9

  • RhoGDI-3 is a new GDP dissociation inhibitor (GDI). Identification of a non-cytosolic GDI protein interacting with the small GTP-binding proteins RhoB and RhoG.

    Zalcman G, Closson V, Camonis J, Honoré N, Rousseau-Merck MF, Tavitian A and Olofsson B

    Unité INSERM 248, Section de Recherche, Institut Curie, 26 rue d'Ulm, 75231 Paris Cedex 05, France.

    RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. We have reported that the transient expression of the endogenous RhoB protein is regulated during the cell cycle, contrasting with the permanent RhoA protein expression (). Using the yeast two-hybrid system to characterize proteins interacting with RhoB, we identified a new mouse Rho GDP dissociation inhibitor, referenced as RhoGDI-3. The NH2-terminal alpha helix of RhoGDI-3 is strongly amphipatic and differs thus from that found in previously described bovine, human, and yeast RhoGDI proteins and mouse and human D4/Ly-GDIs. Contrary to the cytosolic localization of all known GDI proteins, acting on Rab or Rho, RhoGDI-3 is associated to a Triton X-100-insoluble membranous or cytoskeletal subcellular fraction. In the two-hybrid system, RhoGDI-3 interacts specifically with GDP- and GTP-bound forms of post-translationally processed RhoB and RhoG proteins, both of which show a growth-regulated expression in mammalian cells. No interaction is found with RhoA, RhoC, or Rac1 proteins. We show that GDI-3 is able to inhibit GDP/GTP exchange of RhoB and to release GDP-bound but not GTP-bound RhoB from cell membranes.

    The Journal of biological chemistry 1996;271;48;30366-74

  • MesP1: a novel basic helix-loop-helix protein expressed in the nascent mesodermal cells during mouse gastrulation.

    Saga Y, Hata N, Kobayashi S, Magnuson T, Seldin MF and Taketo MM

    Banyu Tsukuba Research Institute (Merck), Ibaraki, Japan.

    A subtractive hybridization strategy was used to isolate putative genes involved in the development of mouse primordial germ cells (PGC). Complimentary DNA was amplified on RNA isolated from the base of the allantois where PGC are located in the 7.5 days post coitum (dpc) mouse embryo. It was then subtracted by hybridization with cDNA amplified on RNA of the anterior region where PGC are absent. A novel gene thus isolated is designated as Mesp1 and encodes a possible transcription factor MesP1 containing a basic helix-loop-helix motif. Its earliest expression was observed at the onset of gastrulation, as early as 6.5 dpc, in the nascent mesodermal cells that first ingressed at the end of the primitive streak. These expressing cells in the lateral and extraembryonic mesoderm showed a wing-shaped distribution. Its initial expression was soon down-regulated at 7.5 dpc before the completion of gastrulation, except at the proximal end of the primitive streak which included the extraembryonic mesoderm and the base of allantois. At 8 dpc, the expression at the base of the allantois moved laterally. This distribution between 7.0 and 8.0 dpc was similar to that of PGC detected by the alkaline phosphatase activity. However, the expression of Mesp1 was down-regulated thereafter, when PGC entered in the migration stage. After birth, Mesp1 expression was detected only in mature testes, but in a different isoform from that expressed in the embryo. Mesp1 was mapped to the mid region of chromosome 7, near the mesodermal deficiency gene (mesd). However, a Southern hybridization study clearly showed that Mesp1 was distinctly different from mesd. The amino acid sequence and its expression pattern suggest that MesP1 plays an important role in the development of the nascent mesoderm including PGC.

    Funded by: NHGRI NIH HHS: HG00734

    Development (Cambridge, England) 1996;122;9;2769-78

  • The protein tyrosine phosphatase epsilon gene maps to mouse chromosome 7 and human chromosome 10q26.

    Elson A, Kozak CA, Morton CC, Weremowicz S and Leder P

    Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.

    We have mapped the mouse protein tyrosine phosphatase epsilon (PTP epsilon, gene symbol Ptpre) gene to the distal region of chromosome 7 by linkage analysis using two sets of multilocus genetic crosses. The human PTP epsilon gene (gene symbol PTPRE) was mapped to chromosome 10q26 by fluorescence in situ hybridization. We have previously documented the existence of two isoforms of PTP epsilon--a transmembranal, receptor-type isoform and a shorter, cytoplasmic one. Both isoforms have been suggested to arise from a single gene through the use of alternative promoters and 5' exons. The identification of a single PTP epsilon locus in both organisms is consistent with this suggestion.

    Genomics 1996;31;3;373-5

  • Cardiac and skeletal muscle troponin I isoforms are encoded by a dispersed gene family on mouse chromosomes 1 and 7.

    Guenet JL, Simon-Chazottes D, Gravel M, Hastings KE and Schiaffino S

    Institut Pasteur de Paris, Unite de Genetique des mammiferes, Paris, France.

    We mapped the locations of the genes encoding the slow skeletal muscle, fast skeletal muscle, and cardiac isoforms of troponin I (Tnni) in the mouse genome by interspecific hybrid backcross analysis of species-specific (C57BL/6 vs Mus spretus) restriction fragment length polymorphisms (RFLPs). The slow skeletal muscle troponin I locus (Tnni1) mapped to Chromosome (Chr) 1. The fast skeletal muscle troponin I locus (Tnni2), mapped to Chr 7, approximately 70 cM from the centromere. The cardiac troponin I locus (Tnni3) also mapped to Chr 7, approximately 5-10 cM from the centromere and unlinked to the fast skeletal muscle troponin I locus. Thus, the troponin I gene family is dispersed in the mouse genome.

    Funded by: Telethon: A.012

    Mammalian genome : official journal of the International Mammalian Genome Society 1996;7;1;13-5

  • Nucleotide sequence of c-H-ras-1 gene from B6C3F1 mice.

    Przybojewska B and Płucienniczak G

    Department of Toxicological Biochemistry, Institute of Occupational Medicine, Lódź, Poland.

    The c-H-ras-1 gene of an B6C3F1 mouse was isolated and nucleotide sequence determined. Our study has revealed that this c-H-ras-1 gene consists of four exons, separated by three introns ranging in size from 150 to 649 bp. The coding parts of the sequence of mouse c-H-ras-1 gene show no important differences as compared with those of the rat, hamster and human gene. More numerous changes were found in introns. The identity of mouse c-H-ras-1 gene with rat, hamster and human ones at the nucleotide level is 86.40%, 80.04% and 67.87%, respectively. Comparison of amino acids in protein sequence of c-H-ras gene of mouse, rat, hamster and human points to high degree of conservation of the gene.

    Acta biochimica Polonica 1996;43;3;575-8

  • Mouse gastric mucin: cloning and chromosomal localization.

    Shekels LL, Lyftogt C, Kieliszewski M, Filie JD, Kozak CA and Ho SB

    Department of Medicine, University of Minnesota, Minneapolis 55417, USA.

    Mucins protect gastric epithelium by maintaining a favourable pH gradient and preventing autodigestion. The purpose of this study was to clone a mouse gastric mucin which would provide a foundation for analysis of mucin gene regulation. Mucin was purified from the glandular portion of gastric specimens and deglycosylated by HF solvolysis. Antibodies against native and deglycosylated mouse gastric mucin (MGM) were raised in chickens. Screening of a mouse stomach cDNA library with the anti-(deglycosylated MGM) antibody yielded partial clones containing a 48 bp tandem repeat and 768 bp of non-repetitive sequence. The 16-amino-acid tandem repeat has a consensus sequence of QTSSPNTGKTSTISTT with 25% serine and 38% threonine. The MGM tandem repeat sequence bears no similarity to previously identified mucins. The MGM non-repetitive region shares sequence similarity with human MUC5AC and, to a lesser extent, human MUC2 and rat intestinal mucin. Northern blot analysis reveals a polydisperse message beginning at 13.5 kb in mouse stomach with no expression in oesophagus, trachea, small intestine, large intestine, caecum, lung or kidney. Immunoreactivity of antibodies against deglycosylated MGM and against a synthetic MGM tandem repeat peptide was restricted to superficial mucous cells, antral glands and Brunner's glands in the pyloric-duodenal region. DNA analysis shows that MGM recognizes mouse and rat DNA but not hamster, rabbit or human DNA. The MGM gene maps to a site on mouse chromosome 7 homologous to the location of a human secretory mucin gene cluster on human chromosome 11p15. Due to sequence similarity and predominant expression in the stomach, the MGM gene may be considered a MUC5AC homologue and named Muc5ac.

    The Biochemical journal 1995;311 ( Pt 3);775-85

  • Hepatocarcinogenesis in BXH recombinant inbred strains of mice: analysis of diverse phenotypic effects of the hepatocarcinogen sensitivity loci.

    Lee GH and Drinkwater NR

    McArdle Laboratory for Cancer Research, University of Wisconsin Medical School 53706, USA.

    The hepatocarcinogen sensitivity (Hcs) loci were originally identified as determinants of the approximately 50-fold higher susceptibility of male C3H/HeJ (C3H) mice to perinatally induced hepatocarcinogenesis relative to male C57BL/6J (B6) mice. These two inbred strains also differ in other phenotypes related to hepatocarcinogenesis, including their incidences of spontaneous liver tumors and the properties of neoplastic hepatic lesions. To test the hypothesis that the Hcs loci also influence these phenotypes, we characterized male mice from B6, C3H, and nine BXH recombinant inbred (RI) strains for spontaneous liver tumor development, the frequency of activating mutations in tumors, and the presence of cytoplasmic inclusions in preneoplastic lesions. By comparing these results to the relative susceptibilities of the parental and RI strains to N,N-diethylnitrosamine (DEN)- and N-ethyl-N-nitrosourea- induced hepatocarcinogenesis in preweanling male mice, we concluded that the C3H alleles of the Hcs loci also positively influence the spontaneous development of liver tumors in male animals. While strain-dependent differences in the frequency of Ha-ras-1 activation in DEN-initiated liver tumors were observed, this phenotype was not correlated with susceptibility to liver tumor induction. The formation of eosinophilic intracytoplasmic inclusion bodies observed specifically in B6 liver tumors, which has been suggested to be associated with the resistance of this strain to hepatocarcinogenesis, also segregated independently of the Hcs loci.

    Funded by: NCI NIH HHS: CA07175, CA22484

    Molecular carcinogenesis 1995;14;3;190-7

  • Mutations in the ras proto-oncogene: clues to etiology and molecular pathogenesis of mouse liver tumors.

    Maronpot RR, Fox T, Malarkey DE and Goldsworthy TL

    National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.

    The mouse liver is a frequent target organ for chemical carcinogenesis (Huff et al., 1988, 1991; Gold et al., 1989) and tumor development exhibits preferential strain sensitivity (Dragani et al., 1992; Drinkwater and Bennett, 1991). In some reports a positive correlation has been observed between the degree of spontaneous liver tumor incidence and the propensity to develop liver tumors after treatment with chemical carcinogens (Della Porta et al., 1967; Flaks, 1968; Dragani et al., 1984, 1987; Diwan et al., 1986; Drinkwater and Ginsler, 1986), but this is not always the case (Grasso and Hardy, 1975; Hanigan et al., 1988; Dragani et al., 1992). Thus, the interpretation of this endpoint in assessing potential health hazards to humans continues to be the subject of active debate. Studies of molecular and genetic factors that modulate the genesis of mouse liver tumors should enhance our understanding of the relevance of this response following exposure to genotoxic as well as nongenotoxic chemicals. To utilize intelligently animal models as surrogates for human carcinogenesis, the validity of rodent tumor endpoints in assessing potential human health hazards from chemical exposure remains an important issue. One approach has been to understand the animal system itself and the mechanisms by which chemicals induce tumors in the animal model. Information regarding the molecular events associated with tumor induction should make the relevance of results from rodent carcinogenicity studies to human risk easier to assess. Results to date have identified activation of ras proto-oncogenes as one early event and an important factor associated with chemical induction of mouse liver neoplasia (Reynolds et al., 1986, 1987; Wiseman et al., 1986), although ras-independent pathways appear to account for an appreciable proportion of some chemically induced mouse liver tumors (Fox et al., 1990; Buchmann et al., 1991). Available data emphasize the complexity of H-ras activation in murine hepatocarcinogenesis. Not only the genetic background of the mouse but also the dose of the carcinogen may influence significantly the number of tumors containing activated H-ras. Both high sensitivity and low sensitivity strains of mice can develop liver tumors which contain activated H-ras oncogenes, showing that the ability to activate this gene does not in itself determine susceptibility to hepatocarcinogenesis. Ras gene mutational profiles in chemically induced liver tumors may be different and distinguishable from those in spontaneous tumors. Since multiple genetic as well as nongenetic events are associated with tumor development, defining a precise role for ras gene mutations when they occur in mouse liver tumors is often difficult.(ABSTRACT TRUNCATED AT 400 WORDS)

    Toxicology 1995;101;3;125-56

  • Distinct genetic loci control development of benign and malignant skin tumours in mice.

    Nagase H, Bryson S, Cordell H, Kemp CJ, Fee F and Balmain A

    CRC Beatson Laboratories, Department of Medical Oncology, University of Glasgow, UK.

    Genetic susceptibility to chemically induced skin cancer in mice is controlled by multiple unlinked genetic loci. Mus spretus mice have dominant resistance genes which confer resistance to interspecific F1 hybrids with susceptible Mus musculus strains. We have mapped three major resistance loci using a combination of Mapmaker/QTL analysis and multiple regression analysis to mouse chromosomes 5 and 7. At least two independent loci on chromosome 7 exert their effects primarily during benign tumour development and have very little influence on tumour progression. On the other hand, probably a single locus on chromosome 5 affects both early and late stages of malignancy. The results indicate that benign and malignant tumours are largely under independent genetic control.

    Funded by: Wellcome Trust

    Nature genetics 1995;10;4;424-9

  • Uroporphyrinogen-III synthase: molecular cloning, nucleotide sequence, expression of a mouse full-length cDNA, and its localization on mouse chromosome 7.

    Xu W, Kozak CA and Desnick RJ

    Department of Human Genetics, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.

    Uroporphyrinogen-III synthase (URO-S; EC, the fourth enzyme in the heme biosynthetic pathway, is responsible for the conversion of hydroxymethylbilane to the cyclic tetrapyrrole, uroporphyrinogen III. The deficient activity of URO-S is the enzymatic defect in congenital erythropoietic porphyria (CEP), an autosomal recessive disorder. For the generation of a mouse model of CEP, the human URO-S cDNA was used to screen 2 x 10(6) recombinants from a mouse adult liver cDNA library. Ten positive clones were isolated, and dideoxy sequencing of the entire 1.6-kb insert of clone pmUROS-1 revealed 5' and 3' untranslated sequences of 144 and 623 bp, respectively, and an open reading frame of 798 bp encoding a 265-amino-acid polypeptide with a predicted molecular mass of 28,501 Da. The mouse and human coding sequences had 80.5 and 77.8% nucleotide and amino acid identity, respectively. The authenticity of the mouse cDNA was established by expression of the active monomeric enzyme in Escherichia coli. In addition, the analysis of two multilocus genetic crosses localized the mouse gene on chromosome 7, consistent with the mapping of the human gene to a position of conserved synteny on chromosome 10. The isolation, expression, and chromosomal mapping of this full-length cDNA should facilitate studies of the structure and organization of the mouse genomic sequence and the development of a mouse model of CEP for characterization of the disease pathogenesis and evaluation of gene therapy.

    Funded by: NCRR NIH HHS: 5 M01 RR00071; NICHD NIH HHS: 5 P30 HD28822; NIDDK NIH HHS: 5 R01 DK26824

    Genomics 1995;26;3;556-62

  • Distribution of p21ras during primary palate formation of non-cleft and cleft strains of mice.

    Wang KY, Chen KC, Chiang CP and Kuo MY

    School of Dentistry, National Taiwan University, Taipei, ROC.

    Cleft lip, with or without cleft palate, is one of the most common defects in craniofacial formation. The primary palatogenesis of mice is similar to that of humans and spontaneous cleft lip is associated with genotype in both mice and humans. To investigate the temporal and spatial expression of ras genes in cleft (A/WySn) and non-cleft strains of mice (BALB/cBy), a broad spectrum ras antibody was used. Positive staining was found in ectodermal, mesenchymal, and neuroepithelial cells of facial prominences before the primary palate formation stage (10 d 20 hr) in both strains. During the primary palate formation stage (11 d 20 hr), positive staining was found in the ectodermal and mesenchymal cells of the facial prominences of the non-cleft strain but not in those of the cleft strain. These results suggest ras genes may play a role in the primary palatogenesis of mice. Cleft lip could be associated with the deficiency of ras gene expression during primary palate formation of mice.

    Journal of oral pathology & medicine : official publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology 1995;24;3;103-8

  • Genetic mapping in human and mouse of the locus encoding TRBP, a protein that binds the TAR region of the human immunodeficiency virus (HIV-1).

    Kozak CA, Gatignol A, Graham K, Jeang KT and McBride OW

    Laboratory of Molecular Microbiology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

    Productive infection with HIV-1, the virus responsible for AIDS, requires the involvement of host cell factors for completion of the replicative cycle, but the identification of these factors and elucidation of their specific functions has been difficult. A human cDNA, TRBP, was recently cloned and characterized as a positive regulator of gene expression that binds to the TAR region of the HIV-1 genome. Here we demonstrate that this factor is encoded by a gene, TARBP2, that maps to human chromosome 12 and mouse chromosome 15, and we also identify and map one human pseudogene (TARBP2P) and two mouse TRBP-related sequences (Tarbp2-rs1, Tarbp2-rs2). The map location of the expressed gene identifies it as a candidate for the previously identified factor encoded on human chromosome 12 that has been shown to be important for expression of HIV-1 genes. Western blotting indicates that despite high sequence conservation in human and mouse, the TARBP2 protein differs in apparent size in primate and rodent cells.

    Genomics 1995;25;1;66-72

  • Spontaneous mutation at codon 61 of the Ha-ras gene in the nascent liver of B6C3F1, C3H/He and C57BL/6 mice.

    Moulds BA and Goodman JI

    Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824-1317.

    DNA was isolated from the liver of young B6C3F1, C3H/He and C57BL/6 mice, 6-9 weeks old. A portion of exon 2 of Ha-ras was amplified by PCR allele-specific amplification. The PCR product was identified by (a) size, (b) presence of a diagnostic restriction site, and (c) direct sequencing. Our results indicate that nascent mouse liver bears a subpopulation of cells which contain a mutation in codon 61 of Ha-ras, specifically an A to G transition at position 2. Therefore, the detection of this mutation in chemically induced mouse liver tumors does not demonstrate that the chemical in question acts as a mutagen. It might act by a nongenotoxic mechanism, i.e., by facilitating a clonal expression of cells bearing this spontaneous mutation.

    Funded by: NIEHS NIH HHS: ES05299

    Mutation research 1994;311;1;1-7

  • SENCAR mouse skin tumors produced by promotion alone have A to G mutations in codon 61 of the c-rasHa gene.

    Sutter C, Greenhalgh DA, Ueda M, Abhyankar S, Ngai P, Hennings H, Schweizer J, Yuspa SH and Strickland JE

    Research Program II, German Cancer Research Center, Heidelberg.

    SENCAR mice, developed by selective breeding for high susceptibility to skin carcinogenesis by initiation with 7,12-dimethylbenz[a]anthracene and promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA), form squamous papillomas in approximately 20% of animals treated repeatedly with TPA, without chemical initiation. DNA from eight skin tumors produced by a TPA-only protocol and four cell lines derived from these tumors was amplified by polymerase chain reaction and analyzed by discriminative oligonucleotide hybridization using oligomers specific for various c-rasHa gene codon 61 sequences. Five tumors and three cell lines had CAA (wild-type) to CGA mutations. In addition, one tumor had a CAA to CTA mutation, for a total of six of eight tumors having an activating mutation at this codon. Two tumors and one cell line had no codon 61 mutations detectable by this method. Since tumors derived from promotion-only protocols presumably originated from constitutively initiated cells, we examined tumor-free skins of untreated newborn and eight-month-old retired breeders and of 78-88-week-old SENCAR mice of both sexes, which were treated with TPA for 10 weeks starting at age 16-28 weeks and were untreated thereafter. Only the wild-type c-rasHa gene codon 61 sequence was seen, suggesting that the constitutively initiated cell population, if present, is below the limit of detection by this method.

    Carcinogenesis 1994;15;9;1975-8

  • Presence and possible role of c-ras and nuclear (c-fos and c-jun) proto-oncogene products in preimplantation embryonic development in mice.

    Ahmad K and Naz RK

    Department of Obstetrics and Gynecology, Albert Einstein College of Medicine, Bronx, New York 10461.

    The presence and possible role of products of nuclear (c-fos and c-jun) and c-ras proto-oncogenes were investigated in preimplantation embryonic development in mice. Polyclonal antibodies to c-fos or c-jun proto-oncogene products did not affect development of in vitro-cultured embryos from two-cell to morula or from morula to late blastocyst stages. However, v-H-ras monoclonal antibody (mAb) to c-ras protein (p21), although it did not inhibit the development of in vitro-cultured embryos from two-cell to morula stages, it significantly (P < .001-.005) inhibited the development of morula to late blastocyst stages in a dose-dependent manner. The effects of v-H-ras mAb were specific, since immunoabsorption with synthetic ras peptide completely blocked inhibitory effects of v-H-ras mAb. Neither c-fos nor c-jun antibodies reacted with specific proteins corresponding to c-fos (62 kDa) and c-jun (39 kDa) products on the Western blots of various murine ova/embryos extracts. However, the c-fos and c-jun antibodies reacted with 62 and 39 kDa protein bands, respectively, on the blot of NIH 3T3 cells extract. The v-H-ras mAb specifically identified 21 +/- 3 kDa protein corresponding to c-ras p21 on the blots of early as well as late blastocyst extracts. The rat control ascites IgG1 did not react with any protein band on the blots of various ova/embryo extracts. The reactions of v-H-ras mAb on the Western blots of blastocyst extracts were specific, since immunoabsorbed antibody was unable to react with any specific band on blots of early or late blastocyst extract. These results were further confirmed by immunoprecipitation procedure utilizing v-H-ras mAb. Again, the v-H-ras mAb immunoprecipitated a 21 kDa band from early as well as late blastocyst extracts. The rat control ascites IgG1 did not react with any band corresponding to p21 in the immunoprecipitation procedure. These results suggest that the specific products of nuclear proto-oncogenes, the c-fos and c-jun, are not detected in murine ova and preimplantation embryos, and the respective antibodies do not inhibit embryogenesis, indicating that they may not play a major role in early embryonic development. On the other hand, the product of c-ras proto-oncogene is specifically expressed in the blastocyst-stage embryos and may have a possible role in preimplantation embryonic development in mice.

    Funded by: NICHD NIH HHS: HD 24425

    Molecular reproduction and development 1993;36;3;297-306

  • Genetic mapping of three GABAA receptor-subunit genes in the mouse.

    Danciger M, Farber DB and Kozak CA

    Jules Stein Eye Institute, UCLA School of Medicine.

    GABAA receptors are a heterogeneous group of heterooligomeric ligand-gated anion channels that represent the main means of synaptic inhibition in neuronal tissue. At least 14 distinct GABAA subunit proteins representing 5 different classes have been identified. Using rat brain cDNAs for the GABAA receptor beta 1-, alpha 2-, and alpha 4-subunits, we have assigned the corresponding murine genes Gabrb-1, Gabra-2, and Gabra-4 to specific chromosomes with somatic cell hybrids, and we have positioned these genes by analysis of the progeny of three genetic crosses. Gabrb-1 and Gabra-2 are tightly linked on mouse Chromosome 5 between the markers Pgm-1 and Kit, and Gabra-4 maps to proximal mouse Chromosome 7 in apparent proximity to the previously mapped Gabrb-3. The Gabrb-1, Gabra-2 pair of genes on Chr 5 maps near the mouse "circling mutation" pi (pirouette).

    Funded by: NEI NIH HHS: EY 00331, EY 08285

    Genomics 1993;16;2;361-5

  • Multiple tumor types appear in a transgenic mouse with the ras oncogene.

    Cardiff RD, Leder A, Kuo A, Pattengale PK and Leder P

    Department of Pathology, School of Medicine, University of California, Davis 95616.

    A transgenic mouse strain with the zeta-globin promoter and the vHa-ras oncogene develops an array of mesenchymal and epithelial neoplasms described here. The predominate mesenchymal tumors were dermal spindle cell tumors, which resembled malignant fibrous histiocytomas found in humans. They were associated with hepatosplenomegaly and developed beneath squamous papillomas. The hepatosplenomegaly was associated with infiltrates of cells that tended toward myelocytic or monocytic differentiation. Other epithelial tumors included keratoacanthomas and squamous cell carcinomas. Squamous cysts, some with squamous cell carcinomas, of the salivary glands and mammary carcinomas were also found. Odontogenic tumors, which sometimes differentiated into ameloblastomas, were one of the more unusual tumor types observed. Other, less frequent tumors were also noted. The tumors described here are a potentially valuable experimental resource that may lead to an understanding of malignant fibrous histiocytoma-like lesions, odontogenic tumors, and tumor progression.

    Funded by: NCI NIH HHS: R01-CA54285

    The American journal of pathology 1993;142;4;1199-207

  • Chromosome mapping of murine susceptibility loci to liver carcinogenesis.

    Gariboldi M, Manenti G, Canzian F, Falvella FS, Pierotti MA, Della Porta G, Binelli G and Dragani TA

    Division of Experimental Oncology A, Istituto Nazionale Tumori, Milan, Italy.

    The validity of mouse liver tumors is controversial in the risk assessment of carcinogenicity of chemicals in humans, because mice used in carcinogenicity bioassays are genetically predisposed to liver tumors. The argument could be resolved once liver tumor susceptibility genes have been cloned and their role in liver tumor development elucidated. We performed a genetic linkage analysis to map murine liver tumor susceptibility genes, as a first step toward their identification. An F2 population of 87 urethane-treated male A/J x C3H/He mice was scored with 83 genetic markers. Three regions, localized on chromosomes 7, 8, and 12, were found to contain putative liver tumor susceptibility genes.

    Cancer research 1993;53;2;209-11

  • A revised map position for the Ha-ras gene on mouse chromosome 7: implications for analysis of genetic alterations in rodent tumors.

    Kemp CJ, Bremner R and Balmain A

    CRC Beatson Laboratories, Beatson Institute for Cancer Research, Glasgow, United Kingdom.

    The mouse Ha-ras gene has previously been mapped to the central region of chromosome 7, 31 cM from the centromere, using an interspecific Mus musculus/Mus spretus backcross (Saunders AM, Seldin MF, Genomics 8:525-535, 1990). However, analysis of mitotic recombinations in mouse skin tumors from intraspecific F1 hybrid mice suggested a more distal location for the Ha-ras gene on chromosome 7 (Bremner R, Balmain A, Cell 61:407-417, 1990). In the study reported here, we demonstrated, by analysis of Ha-ras gene mutations in skin tumors from interspecific M. spretus/M. musculus F1 hybrids, the existence only in M. spretus of a pseudogene or other Ha-ras-related sequence that is probably the sequence originally mapped by Saunders and Seldin. The functional Ha-ras gene maps to the distal region of chromosome 7, and it is this sequence that acquires mutations in chemically induced tumors.

    Molecular carcinogenesis 1993;7;3;147-50

  • Further analysis of c-Ha-ras mutations in papillomas initiated by several polycyclic aromatic hydrocarbons and papillomas from uninitiated, promoter-treated skin in SENCAR mice.

    DiGiovanni J, Beltrán L, Rupp A, Harvey RG and Gill RD

    Department of Carcinogenesis, Science Park- Research Division, University of Texas M. D. Anderson Cancer Center, Smithville 78957.

    In this study we analyzed the mutations in c-Ha-ras from skin papillomas initiated with benzo[a]pyrene (B[a]P), 7-methylbenz[a]anthracene (7-MBA), and 10-fluoro-7-methylbenz[a]anthracene (10-F-7-MBA) and from papillomas induced by treatment with tumor promoter alone. Among the papillomas induced by treatment with tumor promoter alone, 56% (nine of 16) had mutations in c-Ha-ras. These mutations were found primarily in codon 61 and included both A182-->T and A182-->G mutations. In addition, one promoter-induced tumor had a G35-->A mutation in codon 12, and one had a G37-->C mutation in codon 13. The other promoter-induced papillomas did not have detectable mutations in codons 12, 13, or 61. Most of the B[a]P-initiated papillomas (77%; 10 of 13) did not have detectable mutations in c-Ha-ras codons 12, 13, or 61. However, three of these B[a]P-initiated papillomas had c-Ha-ras codon 13 mutations; one had a G37-->C transversion and two had G38-->T transversions. Most of the 7-MBA-initiated tumors and all of the 10-F-7-MBA-initiated tumors had an activated c-Ha-ras gene [nine of 10 (90%) and 11 of 11 (100%), respectively]. These mutations were almost exclusively A182-->T transversions in codon 61 except for two 7-MBA-initiated papillomas that had G37-->C transversions in codon 13. The results suggest that more than one mechanism may contribute to activation of c-Ha-ras by polycyclic aromatic hydrocarbons (PAHs) in mouse skin. Furthermore, the absence of c-Ha-ras mutations in most B[a]P-initiated papillomas, as well as in a significant fraction of those induced by tumor promoter alone, suggests that there may be other molecular targets involved in tumor initiation by PAHs in mouse skin.

    Funded by: NCI NIH HHS: CA 16672, CA 36979; NIEHS NIH HHS: ES 04372

    Molecular carcinogenesis 1993;8;4;272-9

  • Novel RFLPs at protooncogene and cancer-related gene loci on mouse chromosomes.

    Santos J and Pellicer A

    Department of Pathology and Kaplan Cancer Center, New York University School of Medicine, NY 10016.

    DNA probes for the NRAS, HRAS, KRAS2, LCK, RAF1, MET, MYCL1, MYCN, MYB, ERBB2, FOS, CSF1R, and SRC protooncogene loci; the retinoblastoma gene locus (RB1); the tumor virus integration sites INT2, PVT1, and MLV12; and the locus of the tumor-specific antigen T1A were used to screen mouse genomic DNAs from RF/J, CAST/Ei, MOLF/Ei, Mus musculus musculus, M. m. poschiavinus, and M. spretus. Polymorphic DNA fragments for the 18 DNA probes have been identified using Southern blot hybridization and restriction fragment length polymorphism (RFLP) analysis.

    Funded by: NCI NIH HHS: CA36327, CA50434

    Cytogenetics and cell genetics 1993;62;4;217-9

  • Reassignment of the H-ras-1 gene to the Hbb-terminus region of mouse chromosome 7.

    Bianchi AB, Rinchik EM and Conti CJ

    University of Texas, M.D. Anderson Cancer Center, Smithville 78957.

    Funded by: NCI NIH HHS: CA 42157, CA 53123

    Mammalian genome : official journal of the International Mammalian Genome Society 1993;4;4;220-2

  • The rhombotin gene family encode related LIM-domain proteins whose differing expression suggests multiple roles in mouse development.

    Foroni L, Boehm T, White L, Forster A, Sherrington P, Liao XB, Brannan CI, Jenkins NA, Copeland NG and Rabbitts TH

    MRC Laboratory of Molecular Biology, Cambridge, U.K.

    The rhombotin (RBTN1 or Ttg-1) gene was first identified at a chromosome translocation in a T-cell acute leukaemia and later used to isolate two related genes (RBTN2 or Ttg-2 and RBTN3). Complete characterization of these genes in man and mouse shows that all three encode cysteine-rich proteins with typical LIM domains. RBTN1 and RBTN3-derived proteins have 98% identity in the LIM domains but are located on separate chromosomes in man and in mouse while RBTN1 and RBTN2, both located on human chromosome 11p but are on separate chromosomes in mouse, are only 48% identical in this part of the protein. The exon organization of RBTN1 and RBTN3 genes are similar, both having an intron, absent from the RBTN2 gene, in the LIM2-encoding region. The remarkable similarity between rbtn-1 and rbtn-3 proteins is parallelled in their expression patterns in mouse development, since both genes show high expression in restricted areas of the brain, but little lymphoid expression. rbtn-2 expression, however, is more ubiquitous. This gene shows a low level of thymus expression but high expression in fetal liver, adult spleen and B-cell lines, consistent with a role in B-cell development. These results suggest multiple cellular targets for the action of these proteins during development.

    Funded by: PHS HHS: N01-C0-74101

    Journal of molecular biology 1992;226;3;747-61

  • Regional localization of three convertases, PC1 (Nec-1), PC2 (Nec-2), and furin (Fur), on mouse chromosomes.

    Copeland NG, Gilbert DJ, Chrétien M, Seidah NG and Jenkins NA

    Mammalian Genetics Laboratory, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Maryland 21702.

    The genes for three convertases, PC1 (Nec-1), PC2 (Nec-2), and furin (Fur), have been regionally localized on chromosomes 13, 2, and 7, respectively, by interspecific backcross analysis. These results refine previous localizations by in situ hybridization as well as confirm and extend known regions of homology between mouse and human chromosomes.

    Funded by: PHS HHS: N01-C0-74101

    Genomics 1992;13;4;1356-8

  • Cellular proto-oncogene expression following exposure of mice to gamma rays.

    Anderson A and Woloschak GE

    Argonne National Laboratory, Biological and Medical Research Division, Illinois 60439-4833.

    Many studies have shown the importance of altered cellular proto-oncogene expression in contributing to changes in cell survival, cell transformation, and cell cycle progression. In these experiments we examined the effects of total-body exposure of BCF1 mice to gamma rays (3 Gy) in modulating expression of cellular oncogenes in both gut and liver tissues. We selected specific cellular oncogenes (c-fos, c-myc, c-src, and c-H-ras), based on their normal expression in liver and gut tissues from untreated mice. As early as 5 min following whole-body exposure of BCF1 mice to gamma rays we detected induction of mRNA specific for c-src and c-H-ras in both liver and gut tissues. Accumulation of c-fos-RNA was slightly decreased in gut but was unaffected in liver tissue from irradiated mice relative to untreated controls. Accumulation of c-myc mRNA was unaffected in all tissues examined. These experiments document that modulation of cellular proto-oncogene expression can occur as an early event in tissues following irradiation and suggest that this modulation may play a role in radiation-induced cellular changes.

    Radiation research 1992;130;3;340-4

  • A set of anonymous DNA clones as markers for mouse gene mapping.

    Le Roy H, Simon-Chazottes D, Montagutelli X and Guénet JL

    Commissariat à l'énergie atomique, DSV, DPTE, LDC, CEN-FAR, Fontenay, France.

    Mammalian genome : official journal of the International Mammalian Genome Society 1992;3;4;244-6

  • Localization of growth arrest-specific genes on mouse chromosomes 1, 7, 8, 11, 13, and 16.

    Colombo MP, Martinotti A, Howard TA, Schneider C, D'Eustachio P and Seldin MF

    Division of Experimental Oncology D, Istituto Nazionali Tumori, Milano, Italy.

    Growth arrest in NIH3T3 cells is associated with increased expression of a variety of mRNAs, several of which have been isolated as cDNA clones. Six of these growth arrest-specific (Gas) genes were mapped by following the inheritance of DNA restriction fragment length variants (RFLVs) associated with them in panels of recombinant inbred (RI) strains of mice and in the progeny of backcrosses both between laboratory mouse strains and between a laboratory strain and Mus spretus. The six genes are unlinked. Gas-1 maps to Chromosome (Chr) 13, Gas-2 to Chr 7, Gas-3 to Chr 11, Gas-4 to Chr 16, Gas-6 to Chr 8, and Gas-10 to Chr 1.

    Funded by: NHGRI NIH HHS: HG00101

    Mammalian genome : official journal of the International Mammalian Genome Society 1992;2;2;130-4

  • Polymorphisms revealed by PCR with single, short-sized, arbitrary primers are reliable markers for mouse and rat gene mapping.

    Serikawa T, Montagutelli X, Simon-Chazottes D and Guénet JL

    Unité de Génétique des Mammifères de l'Institut Pasteur, Paris, France.

    Ten single, arbitrarily designed oligodeoxynucleotide primers, with 50-70% (G+C) content, were used to amplify by polymerase chain reaction (PCR) sequences with DNA templates from several mouse species (Mus spretus, Mus musculus musculus, and Mus musculus domesticus), as well as DNA from the laboratory rat (Rattus norvegicus). Eight of these ten primers, used either individually or associated in pairs, generated a total of 13 polymorphic products which were used as genetic markers. All of these polymorphic sequences but one were mapped to a particular mouse chromosome, by use of DNA panels prepared either from interspecific backcross progeny of the type (C57BL/6 x Mus spretus)F1 x C57BL/6 or DNA samples prepared from two sets of recombinant inbred (RI) strains (AKXL and BXD). Six rat-specific DNA segments were also assigned to a particular chromosome with DNA panels prepared from 18 rat/mouse somatic cell hybrids segregating rat chromosomes. From these experiments we conclude that, under precisely standardized PCR conditions, the DNA molecules amplified with these arbitrarily designed primers are useful and reliable markers for genetic mapping in both mouse and rat.

    Mammalian genome : official journal of the International Mammalian Genome Society 1992;3;2;65-72

  • Chromosomal localization of the rat Harvey-ras-1 gene (HRAS) by in situ hybridization.

    Gollahon LS and Aldaz CM

    Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville 78957.

    The rat Harvey-ras-1 protooncogene (HRAS) has previously been assigned to rat chromosome 1. In this study we further refine its localization to region 1q41-->q42 through the use of fluorescent in situ hybridization.

    Funded by: NCI NIH HHS: CA-48922

    Cytogenetics and cell genetics 1992;61;2;123-4

  • Analysis of the Ha-ras oncogene in C3H/He mouse liver tumours derived spontaneously or induced with diethylnitrosamine or phenobarbitone.

    Rumsby PC, Barrass NC, Phillimore HE and Evans JG

    BIBRA, Carshalton, Surrey, UK.

    In a study of the mechanisms involved in the induction of tumours by chemicals, the Ha-ras oncogene was analysed in liver tumours induced by the genotoxic carcinogen diethylnitrosamine (DEN), or the non-genotoxic agent phenobarbitone (PB) in C3H/He mice. Mutations were detected using the polymerase chain reaction and oligonucleotide hybridization. Codon 61 mutations were detected in 41% of DEN-induced tumours (19/46), either in the first base (CG----AT, 12/19), a transversion, or the second base (AT----GC, 7/19), a transition. Codon 61 mutations were also found in 29% of spontaneous tumours (all CG----AT, 6/21) but none were detected in PB-induced tumours (0/15) or in normal liver tissue of untreated mice (0/30). No mutations were detected at codon 12. Low and variable expression of the Ha-ras gene was detected in all liver tissues with moderately raised levels (175-200%) in spontaneous, DEN and PB-induced tumours as compared to normal liver tissue. The H-ras gene was methylated to some extent in all liver tissues, with no discernible difference between the treatments. The frequency of the Ha-ras mutation at codon 61 in DEN-induced tumours is greater than in spontaneously arising tumours. This increase is not accompanied by any specific alteration in the expression or methylation of the gene. Since PB-induced tumours do not possess mutations in the Ha-ras gene at codons 12 or 61, the data suggest that the non-genotoxic agent PB induces tumours in the C3H/He mouse liver with a mechanism distinct from that of spontaneous tumours or those that result from treatment with a potent genotoxic carcinogen such as DEN.

    Carcinogenesis 1991;12;12;2331-6

  • Mouse bcl-3: cDNA structure, mapping and stage-dependent expression in B lymphocytes.

    Bhatia K, Huppi K, McKeithan T, Siwarski D, Mushinski JF and Magrath I

    Pediatrics Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.

    Human B-cell chronic lymphocytic leukemias (CLLs) are malignancies of mature B lymphocytes. A subset of these tumors is associated with a non-random t(14; 19) translocation (Ueshima et al., 1985). Recently a gene (bcl-3) has been identified in the region adjacent to the chromosome 19 breakpoint in this translocation (McKeithan et al., 1987; Ohno et al., 1990). We now report the isolation of cDNA clones of mouse bcl-3. The mouse bcl-3-coding region is 1746 bp long and exhibits 80% identity with human bcl-3 at both the nucleotide and amino acid level. The bcl-3 locus maps to the proximal end of mouse chromosome 7, which is syntenic to human chromosome 19. The bcl-3 probe readily detects particularly abundant amounts of a 1.8 kb mRNA in mouse tumors consisting of follicular center mature B cells and large pre-B cells, but not in small pre-B cells. The bcl-3 pattern of expression is distinctive in the spectrum of B-cell maturation in that bcl-3 transcripts are particularly abundant in B-cell lines immortalized just prior to Ig switch. The bcl-3 pattern of expression also bears close resemblance to that of bcl-2 (Gurfinkel et al., 1987), which is frequently associated with human B follicular lymphomas [t(14; 18)] and some chronic lymphocytic leukemias (Adachi et al., 1989; 1990; Adachi & Tsujimoto, 1989).

    Funded by: NCI NIH HHS: CA49207

    Oncogene 1991;6;9;1569-73

  • Transgenic oncogene mice. Tumor phenotype predicts genotype.

    Cardiff RD, Sinn E, Muller W and Leder P

    Department of Pathology, School of Medicine, University of California, Davis 95616.

    The hypothesis that oncogenes influence tumor phenotype was tested by examining slides from 607 mammary tumors from 407 transgenic mice bearing the ras, myc, and/or neu oncogenes. Most tumors (91%) had patterns (phenotypes) that could not be classified by Dunn's standard nomenclature. The nonstandard tumors were described as eosinophilic small cell (SC), basophilic large cell (LC), or pale intermediate cell (IC). The SC tumor was associated with ras, the LC was associated with myc, and the IC was associated with neu, with specificities more than .90 and sensitivities ranging from .99 to .48. Thus, the tumor phenotype could be used to predict which oncogene was present in the animal. The presence of myc in combination with either ras or neu resulted in the predominance of LC tumors and accelerated tumorigenesis. The combination of ras and neu resulted in a decreased tumor incidence. Thus, knowledge of the oncogenes that were present could be used to predict the natural history of the disease.

    The American journal of pathology 1991;139;3;495-501

  • The gene map of the Norway rat (Rattus norvegicus) and comparative mapping with mouse and man.

    Levan G, Szpirer J, Szpirer C, Klinga K, Hanson C and Islam MQ

    Department of Genetics, University of Gothenburg, Sweden.

    The current status of the rat gene map is presented. Mapping information is now available for a total of 214 loci and the number of mapped genes is increasing steadily. The corresponding number of loci quoted at HGM10 was 128. Genes have been assigned to 20 of the 22 chromosomes in the rat. Some aspects of comparative mapping with mouse and man are also discussed. It was found that there is a good correlation between the morphological homologies detectable in rat and mouse chromosomes, on the one hand, and homology at the gene level on the other. For 10 rat synteny groups all the genes so far mapped are syntenic also in the mouse. For the remaining rat synteny groups it appears that the majority of the genes will be syntenic on specific (homologous) mouse chromosomes, with only a few genes dispersed to other members of the mouse karyotype. Furthermore, the data indicate that mouse chromosome 1 genetically corresponds to two rat chromosomes, viz., 9 and 13, equalizing the difference in chromosome number between the two species. Further mappings will show whether the genetic homology will prove to be as extensive as these preliminary results indicate. As might be expected from evolutionary considerations, rat synteny groups are much more dispersed in the human genome. It is clear, however, that many groups of genes have remained syntenic during the period since man and rat shared a common ancestor. One further point was noted. In two cases groups of genes were syntenic in the mouse but dispersed to two chromosomes in rat and man, whereas in a third case a group of genes was syntenic in the rat but dispersed to two chromosomes in mouse and man. This finding argues in favor of the notion that the original gene groups were on separate ancestral chromosomes, which have fused in one rodent species but remained separate in the other and in man.

    Genomics 1991;10;3;699-718

  • v-Ha-ras transgene abrogates the initiation step in mouse skin tumorigenesis: effects of phorbol esters and retinoic acid.

    Leder A, Kuo A, Cardiff RD, Sinn E and Leder P

    Department of Genetics, Harvard Medical School, Boston, MA.

    Experimental carcinogenesis has led to a concept that defines two discrete stages in the development of skin tumors: (i) initiation, which is accomplished by using a mutagen that presumably activates a protooncogene, and (ii) promotion, which is a reversible process brought about most commonly by repeated application of phorbol esters. We have created a transgenic mouse strain that carries the activated v-Ha-ras oncogene fused to the promoter of the mouse embryonic alpha-like, zeta-globin gene. Unexpectedly, these animals developed papillomas at areas of epidermal abrasion and, because abrasion can also serve as a tumor-promoting event in mutagen-treated mouse skin, we tested these mice for their ability to respond to phorbol ester application. Within 6 weeks virtually all treated carrier mice had developed multiple papillomas, some of which went on to develop squamous cell carcinomas and, more frequently, underlying sarcomas. We conclude that the oncogene "preinitiates" carrier mice, replacing the initiation/mutagenesis step and immediately sensitizing them to the action of tumor promoters. In addition, treatment of the mice with retinoic acid dramatically delays, reduces, and often completely inhibits the appearance of promoter-induced papillomas. This strain has use in screening tumor promoters and for assessing antitumor and antiproliferative agents.

    Proceedings of the National Academy of Sciences of the United States of America 1990;87;23;9178-82

  • A molecular genetic linkage map of mouse chromosome 7.

    Saunders AM and Seldin MF

    Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.

    The homology between mouse chromosome 7 and human chromosomes 11, 15, and 19 was examined using interspecific backcross animals derived from mating C3H/HeJ-gld/gld and Mus spretus mice. In an earlier study, we reported on the linkage relationships of 16 loci on mouse chromosome 7 and the homologous relationship between this chromosome and the myotonic dystrophy gene region on human chromosome 19. Segregation analyses were used to extend the gene linkage relationships on mouse chromosome 7 by an additional 21 loci. Seven of these genes (Cyp2a, D19F11S1h, Myod-1, Otf-2, Rnu1p70, Rnu2pa, and Xrcc-1) were previously unmapped in the mouse. Several potential mouse chromosome 7 genes (Mel, Hkr-1, Icam-1, Pvs) did not segregate with chromosome 7 markers, and provisional chromosomal assignments were made. This study establishes a detailed molecular genetic linkage map of mouse chromosome 7 that will be useful as a framework for determining linkage relationships of additional molecular markers and for identifying homologous disease genes in mice and humans.

    Funded by: NHGRI NIH HHS: HG00101; NINDS NIH HHS: NS19999

    Genomics 1990;8;3;525-35

  • Genetic changes in skin tumor progression: correlation between presence of a mutant ras gene and loss of heterozygosity on mouse chromosome 7.

    Bremner R and Balmain A

    Beatson Institute for Cancer Research, Bearsden, Glasgow, Scotland.

    Initiation of tumorigenesis in mouse skin can be accomplished by mutagenesis of the H-ras gene by treatment with chemical carcinogens. A mouse model system has been developed to study the additional genetic events that take place during tumor progression. Skin carcinomas were induced in F1 hybrid mice exhibiting restriction fragment length polymorphisms at multiple chromosomal loci. Analysis of loss of heterozygosity in such tumors showed that imbalance of alleles on mouse chromosome 7, on which the H-ras gene is located, occurs very frequently in skin carcinomas. The chromosomal alterations detected, which included both nondisjunction and mitotic recombination events, were only seen in tumors that have activated ras genes. We conclude that gross chromosomal alterations that elevate the copy number of mutant H-ras and/or lead to loss of normal H-ras are a consistent feature of mouse skin tumor development.

    Cell 1990;61;3;407-17

  • The syntenic relationship of proximal mouse chromosome 7 and the myotonic dystrophy gene region on human chromosome 19q.

    Saunders AM and Seldin MF

    Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.

    The syntenic relationship of the myotonic dystrophy (DM) gene region on human chromosome 19q and proximal mouse chromosome 7 was examined using an interspecific backcross between C3H/HeJ-gld/gld mice and Mus spretus. Segregation analyses were used to order homologs of nine human loci linked with the DM gene. Their order from the centromere was Prkcg, [Apoe, Atpa-2, Ckmm, D19S19h, Ercc-2], Cyp2b, Mag, Lhb. Two other murine loci, D7Rp2 and Ngfg, were also positioned within this interval. Homologs for five human chromosome 11 and 15 loci (Calc, Fes, Hras-1, Igflr, Tyr) were localized within an 18-cM span telomeric to Lhb. Comparison of the gene orders indicates an inversion extending from Prkcg through the interval between Mag and Lhb. This study establishes a detailed map of proximal mouse chromosome 7 that will be useful in identifying and determining whether new human chromosome 19 probes are linked to the DM region.

    Funded by: NINDS NIH HHS: NS19999

    Genomics 1990;6;2;324-32

  • Oncogene-induced liver neoplasia in transgenic mice.

    Sandgren EP, Quaife CJ, Pinkert CA, Palmiter RD and Brinster RL

    Laboratory of Reproductive Physiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.

    Models of hepatocarcinogenesis were generated by directing the expression of SV40 T-antigens, an oncogenic mutant of c-H-ras, or c-myc to the liver of transgenic mice using the albumin enhancer/promoter. The majority of mice carrying the ras transgene (group A) were born with enlarged livers and atypical hepatic architecture, and these all died within several days of birth. The remaining ras transgenic mice (group B) had lower levels of hepatic ras expression, exhibited mild hepatic dysplasia but no liver enlargement, and all ultimately died from development of lung tumors. In contrast, the livers of mice expressing T-antigens were relatively normal at birth, by one month displayed marked dysplasia, and by three to seven months developed multiple nodular adenomas and carcinomas. Myc expression caused mild to severe hepatic dysplasia in young mice, and focal hepatic adenomas in some mice over fifteen months of age. Lines of mice expressing ras (group B), T-antigen, or myc were established and crossed with each other to generate dual transgenic mice expressing oncogene pairs. Each combination resulted in accelerated tumor development, suggesting that these oncoproteins can cooperate with one another during multistep hepatic transformation.

    Funded by: NCI NIH HHS: CA 38635; NICHD NIH HHS: HD 09172

    Oncogene 1989;4;6;715-24

  • Ha-ras and c-myc oncogene expression interferes with morphological and functional differentiation of mammary epithelial cells in single and double transgenic mice.

    Andres AC, van der Valk MA, Schönenberger CA, Flückiger F, LeMeur M, Gerlinger P and Groner B

    Ludwig Institute for Cancer Research, Inselspital, Bern, Switzerland.

    We studied the effects of the tissue-specific and lactogenic hormone-dependent expression of the recombinant whey acidic protein (Wap)-ras and Wap-myc oncogenes on the differentiation of the mammary epithelium in transgenic mice. The histological appearance of mammary glands in pregnant, lactating, and postlactational animals and their ability to express milk protein genes were analyzed. Activated Ha-ras expression caused a decrease of milk protein synthesis during the lactation period. The formation of glandular epithelium and the postlactational regression of epithelial cells were not affected. c-myc expression impaired the development of the glandular epithelium, and milk protein synthesis was decreased strongly. Epithelial cell proliferation continued during lactation and postlactationally. Coexpression of both oncogenes in double transgenic mice synergistically affected differentiation and resulted in a high number of neoplastic foci. Palpable tumors were observed only after a latency of 3-4 months. Tumor cells utilize the Wap promoter hormone independently, express increased levels of Wap-ras and induce adjacent stromal cells to produce tenascin.

    Genes & development 1988;2;11;1486-95

  • Human tyrosinase gene, mapped to chromosome 11 (q14----q21), defines second region of homology with mouse chromosome 7.

    Barton DE, Kwon BS and Francke U

    Department of Human Genetics, Yale University School of Medicine, New Haven, Connecticut 06510.

    The enzyme tyrosinase (monophenol,L-dopa:oxygen oxidoreductase; EC catalyzes the first two steps in the conversion of tyrosine to melanin, the major pigment found in melanocytes. Some forms of oculocutaneous albinism, characterized by the absence of melanin in skin and eyes and by a deficiency of tyrosinase activity, may result from mutations in the tyrosinase structural gene. A recently isolated human tyrosinase cDNA was used to map the human tyrosinase locus (TYR) to chromosome 11, region q14----q21, by Southern blot analysis of somatic cell hybrid DNA and by in situ chromosomal hybridization. A second site of tyrosinase-related sequences was detected on the short arm of chromosome 11 near the centromere (p11.2----cen). Furthermore, we have confirmed the localization of the tyrosinase gene in the mouse at or near the c locus on chromosome 7. Comparison of the genetic maps of human chromosome 11 and mouse chromosome 7 leads to hypotheses regarding the evolution of human chromosome 11.

    Funded by: NIGMS NIH HHS: GM26105

    Genomics 1988;3;1;17-24

  • The structural gene for the M1 subunit of ribonucleotide reductase maps to chromosome 11, band p15, in human and to chromosome 7 in mouse.

    Brissenden JE, Caras I, Thelander L and Francke U

    Department of Human Genetics, Yale University School of Medicine, New Haven, Connecticut 06510.

    The genes for the M1 subunit of the enzyme ribonucleotide reductase have been mapped in the human and the murine species by use of two independently derived mouse cDNA clones. Southern blot analysis of rodent x human somatic cell hybrid DNAs confirmed the assignment of RRM1 to the short arm of human chromosome 11. In situ hybridization to human metaphase chromosomes revealed a peak of silver grains over the distal third of band 11p15, a region corresponding to subbands p15.4----p15.5. The mouse Rrml locus was assigned to chromosome 7, where it forms part of a conserved syntenic group of at least seven other genes assigned to human chromosome band 11p15.

    Funded by: NIGMS NIH HHS: GM26105

    Experimental cell research 1988;174;1;302-8

  • The rat gene map.

    Szpirer C, Szpirer J, Islam MQ and Levan G

    Current topics in microbiology and immunology 1988;137;33-8

  • Isolation and characterization of the 5' flanking region of the mouse c-Harvey-ras gene.

    Brown K, Bailleul B, Ramsden M, Fee F, Krumlauf R and Balmain A

    Beatson Institute for Cancer Research, Glasgow, Scotland.

    The complete 5' flanking region of the murine c-Ha-ras gene was cloned and sequenced. An untranslated exon (-1) was identified and the promoter region of the gene located. Like the rat and human homologues, the murine promoter is GC rich and contains several GC boxes together with a CAAT element, but lacks a TATA box, an arrangement similar to that found in many housekeeping genes. From primer extension studies, the gene was shown to have three transcriptional start sites, whose positions differ from those previously found for the human gene. No alterations in these start sites were detected between the normal gene and activated Ha-ras genes from mouse skin tumors. A region of strong homology between mouse, rat, and human Ha-ras genes exists within the large intron separating exon (-1) from the first coding exon. In addition, from chloramphenicol acetyltransferase assays, the upstream region has promoter activity which appears to be enhanced by the inclusion of sequences within this intron.

    Molecular carcinogenesis 1988;1;3;161-70

  • Ha-ras oncogene expression directed by a milk protein gene promoter: tissue specificity, hormonal regulation, and tumor induction in transgenic mice.

    Andres AC, Schönenberger CA, Groner B, Hennighausen L, LeMeur M and Gerlinger P

    The activated human Ha-ras oncogene was subjected to the control of the promoter region of the murine whey acidic protein (Wap) gene, which is expressed in mammary epithelial cells in response to lactogenic hormones. The Wap-ras gene was stably introduced into the mouse germ line of five transgenic mice (one male and four females). Wap-ras expression was observed in the mammary glands of lactating females in two lines derived from female founders. The tissue-directed and hormone-dependent Wap expression was conferred on the Ha-ras oncogene. The signals governing Wap expression are located within 2.5 kilobases of 5' flanking sequence. The other two lines derived from female founders did not express the chimeric gene. In the line derived from the male founder, the Wap-ras gene is integrated into the Y chromosome. Expression was found in the salivary gland of male animals only. After a long latency, Wap-ras-expressing mice developed tumors. The tumors arose in tissues expressing Wap-ras--i.e., mammary or salivary glands. Compared to the corresponding nonmalignant tissues, Wap-ras expression was enhanced in the tumors.

    Proceedings of the National Academy of Sciences of the United States of America 1987;84;5;1299-303

  • Chromosomal mapping of beta-globin and albino loci in the domestic cat. A conserved mammalian chromosome group.

    O'Brien SJ, Haskins ME, Winkler CA, Nash WG and Patterson DF

    Siamese cats are homozygous for the recessive cs allele of the color (albino) locus. The c locus is shown here by backcross analysis to be linked to the beta-hemoglobin (HBB) locus in the cat at a distance of approximately eight centiMorgans. The HBB locus and, by inference, the c locus were assigned to feline chromosome D1, by analysis of genomic DNAs from a panel of rodent X cat somatic cell hybrids with a molecular clone of the human beta-globin locus. Evolutionary conservation of the synthetic homology of feline chromosome D1 and human chromosome 11 is extensive. Comparison of high resolution G-trypsin-banded preparations of the two chromosomes permitted cytological alignment of the long arm of the conserved chromosomes providing that a minimum of one paracentric inversion is hypothesized. The placement of the albino locus on conserved syntenic groups of several markers (HBB, HRAS, LDHA) in both cat and mouse strongly indicates the conservative placement of the as yet unmapped human albino locus in the homologous syntenic group on human chromosome 11p.

    Funded by: NCRR NIH HHS: RR 02512; NIGMS NIH HHS: GM 32592

    The Journal of heredity 1986;77;6;374-8

  • Assignment of RAS proto-oncogenes in Chinese hamsters: implications for mammalian gene linkage conservation and neoplasia.

    Stallings RL, Crawford BD, Black RJ and Chang EH

    HRAS and KRAS are the cellular homologs of the oncogenic transforming genes found in the Harvey strain of murine sarcoma virus and the Kirsten murine sarcoma virus, respectively. Phyla as diverse as insects, birds, and mammals possess distinct HRAS and KRAS sequences, suggesting that these genes are essential to metazoa. In this report, we used a clone panel of Chinese hamster X mouse C11D somatic cell hybrids segregating hamster chromosomes to map those genes. Southern filter hybridization analyses of the hybrids revealed that hamster HRAS and KRAS gene sequences are on chromosomes 3 and 8, respectively. These gene assignments are consistent with the conservation of autosomal gene linkage groups observed among hamsters, humans, and mice and may provide insight into specific chromosomal alterations that have been observed during the spontaneous neoplastic transformation of Chinese hamster fibroblasts in vitro.

    Cytogenetics and cell genetics 1986;43;1-2;2-5

  • Transforming activity of the c-Ha-ras oncogene having two point mutations in codons 12 and 61.

    Sekiya T, Prassolov VS, Fushimi M and Nishimura S

    A recombinant plasmid carrying the human c-Ha-ras gene with two point mutations in codons 12 and 61 was constructed and its transforming activity on mouse NIH 3T3 cells was compared with those of genes with a single mutation in either codon 12 or 61. Quantitative analyses revealed that the gene with two mutations had essentially the same transforming activity as the genes with single mutations. These results indicate that a single mutation of the c-Ha-ras gene in either codon 12 or 61 is sufficient to activate the gene and that neither of the two mutation sites involved in activation of the gene needs to be intact for transforming activity.

    Japanese journal of cancer research : Gann 1985;76;9;851-5

  • Assignment of three rat cellular RAS oncogenes to chromosomes 1, 4, and X.

    Szpirer J, Defeo-Jones D, Ellis RW, Levan G and Szpirer C

    Mouse hepatoma-rat hepatocyte hybrids that segregate rat chromosomes were used to determine the chromosomal localization of rat cellular RAS genes. The cellular KRAS gene, homologous to the Kirsten sarcoma virus oncogene was mapped to rat chromosome 4, a chromosome that is often present in three copies in rat neurogenic tumor cells and transformed glial cells. The rat cellular HRAS-1 gene, homologous to the Harvey sarcoma virus oncogene was assigned to chromosome 1, whereas its intron-less counterpart HRAS-2 was mapped to the X chromosome. Since the human HRAS-2 also resides on the X chromosome, it appears that the cellular HRAS-2 gene (or pseudogene) conserved its chromosomal localization during mammalian evolution.

    Somatic cell and molecular genetics 1985;11;1;93-7

  • Molecular cloning and the total nucleotide sequence of the human c-Ha-ras-1 gene activated in a melanoma from a Japanese patient.

    Sekiya T, Fushimi M, Hori H, Hirohashi S, Nishimura S and Sugimura T

    The transforming gene of malignant melanoma tissue obtained from a Japanese patient and maintained in nude mice has been cloned in its biologically active form and identified as the c-Ha-ras-1 gene, a homologue of the viral Ha-ras gene. Nucleotide sequence analysis revealed that the genetic alteration responsible for the transforming activity of the melanoma oncogene was localized to a single point mutation in the second exon. The transversion of adenine to thymine results in the substitution of leucine for glutamine as amino acid residue 61 of the predicted p21 protein. Other nucleotide sequences spanning a 2.9-kilobase segment including the entire exons and introns were found to be exactly the same as those in a proto-oncogene from a normal Caucasian reported previously, except for base alterations explained as polymorphic differences.

    Proceedings of the National Academy of Sciences of the United States of America 1984;81;15;4771-5

  • Chromosome assignments of four mouse cellular homologs of sarcoma and leukemia virus oncogenes.

    Sakaguchi AY, Lalley PA, Zabel BU, Ellis RW, Scolnick EM and Naylor SL

    Molecular probes for the oncogenes of Rous sarcoma virus (v-src), avian myeloblastosis virus (v-myb), Kirsten murine sarcoma virus (v-Ki-ras), and Harvey murine sarcoma virus (v-Ha-ras) were hybridized to the DNA from mouse-Chinese hamster somatic cell hybrids. The v-src, v-myb, v-Ki-ras, and v-Ha-ras genes each detected one or a few homologous mouse DNA fragments whose segregation was analyzed in cell hybrids. Mouse cellular homologs c-src, c-Ki-ras, c-Ha-ras, and c-myb segregated concordantly with chromosomes 2, 6, 7, and 10, respectively. Comparison with the known locations of human c-src (chromosome 20) and human c-Ha-ras1 (chromosome 11 short arm) suggests that the human and mouse homologs of these two viral oncogenes reside in conserved linkage groups. The c-Ki-ras gene on mouse chromosome 6 might reside also in a conserved linkage group, along with glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase. However, direct confirmation of this suggestion must await a demonstration that c-Ki-ras on mouse chromosome 6 is homologous to c-Ki-ras2 on the short arm of human chromosome 12.

    Funded by: NCI NIH HHS: CA16056; NIGMS NIH HHS: GM20454

    Proceedings of the National Academy of Sciences of the United States of America 1984;81;2;525-9

  • Expression of H-Y antigen by female mice carrying Sxr.

    Simpson E, McLaren A, Chandler P and Tomonari K

    The minor transplantation antigen H-Y can cause graft rejection and can stimulate the generation of H-2-restricted T cell responses. We have used both responses to type karyotypically abnormal mice for the presence of H-Y antigen, in order to investigate the role of H-Y in sex determination. The mice under scrutiny were Sxr5-carrying females derived by crossing females carrying the T(16;X)16H translocation with Sxr carrying males. These females were fully fertile and were H-Y positive. These results are consistent with the testis determining gene, Tdy, which may or may not be H-Y, having a threshold effect on testis differentiation during embryogenesis. They also show that the presence of H-Y in adult females does not impair reproduction.

    Transplantation 1984;37;1;17-21

  • Abstracts of meeting presentations: Human gene mapping 7, Los Angeles Conference (1983), Seventh International Workshop on Human Gene Mapping.

    No authors listed

    Cytogenetics and cell genetics 1984;37;1-4;399-616

  • Assignment of murine cellular Harvey ras gene to chromosome 7.

    Pravtcheva DD, Ruddle FH, Ellis RW and Scolnick EM

    Mouse-Chinese hamster somatic cell hybrids containing various combinations of mouse chromosomes were analyzed for the presence of the mouse c-Ha-ras (1) sequences after restriction endonuclease digestion and hybridization with a 32P-labeled Ha-ras specific probe according to the procedure of Southern (2). The presence of the mouse c-Ha-ras containing fragment was correlated with the presence of mouse chromosome 7 in the hybrids.

    Somatic cell genetics 1983;9;6;681-6

  • Genetic mapping of the mouse oncogenes c-Ha-ras-1 and c-fes to chromosome 7.

    Kozak CA, Sears JF and Hoggan MD

    The mouse homologs of the cellular oncogenes c-Ha-ras-1 of Harvey sarcoma virus and c-fes of feline sarcoma virus were both mapped to chromosome 7 by Southern blot analysis of hamster-mouse somatic cell hybrid DNAs.

    Journal of virology 1983;47;1;217-20

  • Expression of c-onc genes: c-fos transcripts accumulate to high levels during development of mouse placenta, yolk sac and amnion.

    Müller R, Verma IM and Adamson ED

    The c-onc genes c-fos and c-fms are expressed at high levels specifically in mouse extra-embryonal tissues. Here, we report the results of a detailed analysis of expression of these genes within the developing placenta and extra-embryonal membranes (i.e., yolk sac and amnion). (i) The c-fos gene is expressed at relatively high, but nearly constant levels in the undissected placenta throughout gestation. (ii) The level of c-fos transcripts is greater than or equal to 15-fold higher in the separated outer portion of the midgestation placenta (primarily undifferentiated fetus-derived cytotrophoblast maternal decidua) relative to the inner moiety (predominantly differentiated syncytiotrophoblast). (iii) In the inner placenta and in the extra-embryonal membranes c-fos transcripts accumulate as gestation proceeds. The abundance of c-fos transcripts in the micro-surgically isolated 18th day amnion reaches a level which is two orders of magnitude greater than that in midgestation fetuses, and is thus close to the level of v-fos transcripts in virus-transformed cells. (iv) The distribution of c-fos transcripts within the developing extra-embryonal tissues is markedly different from that of the c-fms gene. It is suggested that the c-fos and c-fms proteins may participate in differentiation, growth or transport processes occurring in mouse extra-embryonal tissues.

    Funded by: NCI NIH HHS: CA 21408, CA 28427, P30 CA 30199

    The EMBO journal 1983;2;5;679-84

  • Differential expression of cellular oncogenes during pre- and postnatal development of the mouse.

    Müller R, Slamon DJ, Tremblay JM, Cline MJ and Verma IM

    Nature 1982;299;5884;640-4

  • T24 human bladder carcinoma oncogene is an activated form of the normal human homologue of BALB- and Harvey-MSV transforming genes.

    Santos E, Tronick SR, Aaronson SA, Pulciani S and Barbacid M

    A transforming gene isolated from T24 human bladder carcinoma cells is closely related to the BALB murine sarcoma virus (MSV) onc gene (v-bas). This transforming gene is localized to a 4.6 kilobase pair (kbp) region and is expressed as a 1.2-kbp polyadenylated transcript, which contains v-bas related sequences. Moreover, antisera known to detect the immunologically related onc gene products of BALB- and Harvey-MSVs recognized elevated levels of a related protein in T24 cells. The normal human homologue of v-bas was found to be indistinguishable from the T24 oncogene by heteroduplex and restriction enzyme analysis. These results imply that rather subtle genetic alterations have led to the activation of the normal human homologue of v-bas as a human transforming gene.

    Nature 1982;298;5872;343-7

  • The p21 src genes of Harvey and Kirsten sarcoma viruses originate from divergent members of a family of normal vertebrate genes.

    Ellis RW, Defeo D, Shih TY, Gonda MA, Young HA, Tsuchida N, Lowy DR and Scolnick EM

    The Harvey and Kirsten strains of murine sarcoma virus encode enzymatically and serologically related p21 src proteins which are required for virally mediated cellular transformation. The genes in each virus encoding p21 show such extensive divergence from each other that cloned probes from these genes detect distinct sets of cellular genes in the DNA from several vertebrate species. These data suggest that cellular p21 sarc genes constitute a divergent family of vertebrate genes that can regulate the growth of cells.

    Nature 1981;292;5823;506-11

  • Identification of a normal vertebrate cell protein related to the p21 src of Harvey murine sarcoma virus.

    Langbeheim H, Shih TY and Scolnick EM

    Virology 1980;106;2;292-300

  • Guanine nucleotide-binding and autophosphorylating activities associated with the p21src protein of Harvey murine sarcoma virus.

    Shih TY, Papageorge AG, Stokes PE, Weeks MO and Scolnick EM

    The purified p21src protein of Harvey sarcoma virus shows a guanine nucleotide-binding activity and, in addition, at elevated temperature an autophosphorylating activity at a threonine residue using as phosphoryl donor GTP or dGTP but not ATP or dATP. These biochemical activities are unique among those associated with transforming proteins of RNA-containing or DNA-containing tumour viruses.

    Nature 1980;287;5784;686-91

Gene lists (6)

Gene List Source Species Name Description Gene count
L00000001 G2C Mus musculus Mouse PSD Mouse PSD adapted from Collins et al (2006) 1080
L00000007 G2C Mus musculus Mouse NRC Mouse NRC adapted from Collins et al (2006) 186
L00000008 G2C Mus musculus Mouse PSP Mouse PSP adapted from Collins et al (2006) 1121
L00000021 G2C Mus musculus Pocklington M3 Cluster 3 (mouse) from Pocklington et al (2006) 30
L00000062 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus 984
L00000072 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list 1556
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EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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