G2Cdb::Gene report

Gene id
Gene symbol
Homo sapiens
Rho/Rac guanine nucleotide exchange factor (GEF) 2
G00000245 (Mus musculus)

Databases (7)

ENSG00000116584 (Ensembl human gene)
9181 (Entrez Gene)
559 (G2Cdb plasticity & disease)
ARHGEF2 (GeneCards)
607560 (OMIM)
Marker Symbol
Protein Sequence
Q92974 (UniProt)

Synonyms (4)

  • GEF-H1
  • KIAA0651
  • LFP40
  • P40

Literature (38)

Pubmed - other

  • Mutation of ARHGAP9 in patients with coronary spastic angina.

    Takefuji M, Asano H, Mori K, Amano M, Kato K, Watanabe T, Morita Y, Katsumi A, Itoh T, Takenawa T, Hirashiki A, Izawa H, Nagata K, Hirayama H, Takatsu F, Naoe T, Yokota M and Kaibuchi K

    Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa-ku, Nagoya, Japan.

    Coronary artery spasm has an important function in the etiology of variant angina and other acute coronary syndromes. Abnormal activation of Rho-family GTPases has been observed in cardiovascular disorders, but the function of genetic variability in Rho-family GTPases remains to be evaluated in cardiovascular disorders. We examined the genetic variability of Rho-family GTPases and their regulators in coronary artery spasm. We performed a comprehensive candidate gene analysis of 67 single nucleotide polymorphisms with amino-acid substitution in Rho-family GTPases and their regulators in 103 unrelated Japanese patients with acetylcholine-induced coronary artery spasm and 102 control Japanese subjects without acetylcholine-induced coronary artery spasm. We noted an association of the single nucleotide polymorphism of ARHGAP9 (rs11544238, Ala370Ser) with coronary artery spasm (odds ratio =2.67). We found that ARHGAP9 inactivated Rac as RacGAP and that the mRNA level of ARHGAP9 was strongly detected in hematopoietic cells. ARHGAP9 negatively regulated cell migration. The Ala370Ser polymorphism counteracted ARHGAP9-reduced cell migration, spreading and adhesion. The Ala370Ser polymorphism in the ARHGAP9 gene is associated with coronary artery spasm. These data suggest that the polymorphism of ARHGAP9 has a critical function in the infiltration of hematopoietic cells into the endothelium and inflammation leading to endothelial dysfunction.

    Journal of human genetics 2010;55;1;42-9

  • Semaphorin 4D signaling requires the recruitment of phospholipase C gamma into the plexin-B1 receptor complex.

    Swiercz JM, Worzfeld T and Offermanns S

    Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany. jakub.swiercz@mpi-bn.mpg.de

    The semaphorin 4D (Sema4D) receptor plexin-B1 constitutively interacts with particular Rho guanine nucleotide exchange factors (RhoGEFs) and thereby mediates Sema4D-induced RhoA activation, a process which involves the tyrosine phosphorylation of plexin-B1 by ErbB-2. It is, however, unknown how plexin-B1 phosphorylation regulates RhoGEF activity. We show here that activation of plexin-B1 by Sema4D and its subsequent tyrosine phosphorylation creates docking sites for the SH2 domains of phospholipase Cgamma (PLCgamma). PLCgamma is thereby recruited into the plexin-B1 receptor complex and via its SH3 domain activates the Rho guanine nucleotide exchange factor PDZ-RhoGEF. PLCgamma-dependent RhoGEF activation is independent of its lipase activity. The recruitment of PLCgamma has no effect on the R-Ras GTPase-activating protein activity of plexin-B1 but is required for Sema4D-induced axonal growth cone collapse as well as for the promigratory effects of Sema4D on cancer cells. These data demonstrate a novel nonenzymatic function of PLCgamma as an important mechanism of plexin-mediated signaling which links tyrosine phosphorylation of plexin-B1 to the regulation of a RhoGEF protein and downstream cellular processes.

    Molecular and cellular biology 2009;29;23;6321-34

  • Modulation of Rho guanine exchange factor Lfc activity by protein kinase A-mediated phosphorylation.

    Meiri D, Greeve MA, Brunet A, Finan D, Wells CD, LaRose J and Rottapel R

    Ontario Cancer Institute, Toronto Medical Discovery Tower, MaRS East Tower, 101 College St., Toronto, Ontario M5G 1L7, Canada.

    Lfc is a guanine nucleotide exchange factor (GEF) for Rho that demonstrates an unusual ability to associate with microtubules. While several phosphorylated residues have been detected in the Lfc polypeptide, the mechanism(s) by which phosphorylation regulates the exchange activity of Lfc remains unclear. We confirm that Lfc is a phosphorylated protein and demonstrate that 14-3-3 interacts directly and in a phosphorylation-dependent manner with Lfc. We identify AKAP121 as an Lfc-binding protein and show that Lfc is phosphorylated in an AKAP-dependent manner by protein kinase A (PKA). Forskolin treatment induced 14-3-3 binding to Lfc and suppressed the exchange activity of wild-type Lfc on RhoA. Importantly, a mutant of Lfc that is unable to associate with 14-3-3 proteins was resistant to inhibition by forskolin. Tctex-1, a dynein motor light chain, binds to Lfc in a competitive manner with 14-3-3.

    Molecular and cellular biology 2009;29;21;5963-73

  • Guanine nucleotide exchange factor-H1 regulates cell migration via localized activation of RhoA at the leading edge.

    Nalbant P, Chang YC, Birkenfeld J, Chang ZF and Bokoch GM

    Departments of Immunology and Microbial Science, and Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. perihan.nalbant@uni-due.de

    Cell migration involves the cooperative reorganization of the actin and microtubule cytoskeletons, as well as the turnover of cell-substrate adhesions, under the control of Rho family GTPases. RhoA is activated at the leading edge of motile cells by unknown mechanisms to control actin stress fiber assembly, contractility, and focal adhesion dynamics. The microtubule-associated guanine nucleotide exchange factor (GEF)-H1 activates RhoA when released from microtubules to initiate a RhoA/Rho kinase/myosin light chain signaling pathway that regulates cellular contractility. However, the contributions of activated GEF-H1 to coordination of cytoskeletal dynamics during cell migration are unknown. We show that small interfering RNA-induced GEF-H1 depletion leads to decreased HeLa cell directional migration due to the loss of the Rho exchange activity of GEF-H1. Analysis of RhoA activity by using a live cell biosensor revealed that GEF-H1 controls localized activation of RhoA at the leading edge. The loss of GEF-H1 is associated with altered leading edge actin dynamics, as well as increased focal adhesion lifetimes. Tyrosine phosphorylation of focal adhesion kinase and paxillin at residues critical for the regulation of focal adhesion dynamics was diminished in the absence of GEF-H1/RhoA signaling. This study establishes GEF-H1 as a critical organizer of key structural and signaling components of cell migration through the localized regulation of RhoA activity at the cell leading edge.

    Funded by: NIGMS NIH HHS: GM-39434, R01 GM039434

    Molecular biology of the cell 2009;20;18;4070-82

  • Defining the human deubiquitinating enzyme interaction landscape.

    Sowa ME, Bennett EJ, Gygi SP and Harper JW

    Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.

    Deubiquitinating enzymes (Dubs) function to remove covalently attached ubiquitin from proteins, thereby controlling substrate activity and/or abundance. For most Dubs, their functions, targets, and regulation are poorly understood. To systematically investigate Dub function, we initiated a global proteomic analysis of Dubs and their associated protein complexes. This was accomplished through the development of a software platform called CompPASS, which uses unbiased metrics to assign confidence measurements to interactions from parallel nonreciprocal proteomic data sets. We identified 774 candidate interacting proteins associated with 75 Dubs. Using Gene Ontology, interactome topology classification, subcellular localization, and functional studies, we link Dubs to diverse processes, including protein turnover, transcription, RNA processing, DNA damage, and endoplasmic reticulum-associated degradation. This work provides the first glimpse into the Dub interaction landscape, places previously unstudied Dubs within putative biological pathways, and identifies previously unknown interactions and protein complexes involved in this increasingly important arm of the ubiquitin-proteasome pathway.

    Funded by: NIA NIH HHS: AG085011, R01 AG011085, R01 AG011085-16; NIGMS NIH HHS: GM054137, GM67945, R01 GM054137, R01 GM054137-14, R01 GM067945

    Cell 2009;138;2;389-403

  • Use of expression data and the CGEMS genome-wide breast cancer association study to identify genes that may modify risk in BRCA1/2 mutation carriers.

    Walker LC, Waddell N, Ten Haaf A, kConFab Investigators, Grimmond S and Spurdle AB

    Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Brisbane, QLD, Australia.

    Germline mutations in BRCA1 or BRCA2 confer an increased lifetime risk of developing breast or ovarian cancer, but variable penetrance suggests that cancer susceptibility is influenced in part by modifier genes. Microarray expression profiling was conducted for 69 irradiated lymphoblastoid cell lines derived from healthy controls, or from cancer-affected women with a strong family history of breast and ovarian cancer carrying pathogenic mutations in BRCA1 or BRCA2, or with no BRCA1/2 mutations (BRCAX). Genes discriminating between BRCA1, BRCA2 or BRCAX and controls were stratified based on irradiation response and/or cell cycle involvement. Gene lists were aligned against genes tagged with single nucleotide polymorphisms (SNPs) determined by the Cancer Genetic Markers of Susceptibility (CGEMS) Breast Cancer Whole Genome Association Scan to be nominally associated with breast cancer risk. Irradiation responsive genes whose expression correlated with BRCA1 and/or BRCA2 mutation status were more likely to be tagged by risk-associated SNPs in the CGEMS dataset (BRCA1, P = 0.0005; BRCA2, P = 0.01). In contrast, irradiation responsive genes correlating with BRCAX status were not enriched in the CGEMS dataset. Classification of expression data by involvement in cell cycle processes did not enrich for genes tagged by risk-associated SNPs, for BRCA1, BRCA2 or BRCAX groups. Using a novel combinatorial approach, we have identified a subset of irradiation responsive genes as high priority candidate BRCA1/2 modifier genes. Similar approaches may be used to identify genes and underlying genetic risk factors that interact with exogenous stimulants to cause or modify any disease, without a priori knowledge of the pathways involved.

    Breast cancer research and treatment 2008;112;2;229-36

  • GEF-H1 couples nocodazole-induced microtubule disassembly to cell contractility via RhoA.

    Chang YC, Nalbant P, Birkenfeld J, Chang ZF and Bokoch GM

    Departments of Immunology and Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

    The RhoA GTPase plays a vital role in assembly of contractile actin-myosin filaments (stress fibers) and of associated focal adhesion complexes of adherent monolayer cells in culture. GEF-H1 is a microtubule-associated guanine nucleotide exchange factor that activates RhoA upon release from microtubules. The overexpression of GEF-H1 deficient in microtubule binding or treatment of HeLa cells with nocodazole to induce microtubule depolymerization results in Rho-dependent actin stress fiber formation and contractile cell morphology. However, whether GEF-H1 is required and sufficient to mediate nocodazole-induced contractility remains unclear. We establish here that siRNA-mediated depletion of GEF-H1 in HeLa cells prevents nocodazole-induced cell contraction. Furthermore, the nocodazole-induced activation of RhoA and Rho-associated kinase (ROCK) that mediates phosphorylation of myosin regulatory light chain (MLC) is impaired in GEF-H1-depleted cells. Conversely, RhoA activation and contractility are rescued by reintroduction of siRNA-resistant GEF-H1. Our studies reveal a critical role for a GEF-H1/RhoA/ROCK/MLC signaling pathway in mediating nocodazole-induced cell contractility.

    Funded by: NIGMS NIH HHS: GM44428, R01 GM044428

    Molecular biology of the cell 2008;19;5;2147-53

  • Systematic analysis of the protein interaction network for the human transcription machinery reveals the identity of the 7SK capping enzyme.

    Jeronimo C, Forget D, Bouchard A, Li Q, Chua G, Poitras C, Thérien C, Bergeron D, Bourassa S, Greenblatt J, Chabot B, Poirier GG, Hughes TR, Blanchette M, Price DH and Coulombe B

    Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada.

    We have performed a survey of soluble human protein complexes containing components of the transcription and RNA processing machineries using protein affinity purification coupled to mass spectrometry. Thirty-two tagged polypeptides yielded a network of 805 high-confidence interactions. Remarkably, the network is significantly enriched in proteins that regulate the formation of protein complexes, including a number of previously uncharacterized proteins for which we have inferred functions. The RNA polymerase II (RNAP II)-associated proteins (RPAPs) are physically and functionally associated with RNAP II, forming an interface between the enzyme and chaperone/scaffolding proteins. BCDIN3 is the 7SK snRNA methylphosphate capping enzyme (MePCE) present in an snRNP complex containing both RNA processing and transcription factors, including the elongation factor P-TEFb. Our results define a high-density protein interaction network for the mammalian transcription machinery and uncover multiple regulatory factors that target the transcription machinery.

    Funded by: Canadian Institutes of Health Research: 14309-3, 82851-1

    Molecular cell 2007;27;2;262-74

  • GEF-H1 modulates localized RhoA activation during cytokinesis under the control of mitotic kinases.

    Birkenfeld J, Nalbant P, Bohl BP, Pertz O, Hahn KM and Bokoch GM

    Departments of Immunology and Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

    Formation of the mitotic cleavage furrow is dependent upon both microtubules and activity of the small GTPase RhoA. GEF-H1 is a microtubule-regulated exchange factor that couples microtubule dynamics to RhoA activation. GEF-H1 localized to the mitotic apparatus in HeLa cells, particularly at the tips of cortical microtubules and the midbody, and perturbation of GEF-H1 function induced mitotic aberrations, including asymmetric furrowing, membrane blebbing, and impaired cytokinesis. The mitotic kinases Aurora A/B and Cdk1/Cyclin B phosphorylate GEF-H1, thereby inhibiting GEF-H1 catalytic activity. Dephosphorylation of GEF-H1 occurs just prior to cytokinesis, accompanied by GEF-H1-dependent GTP loading on RhoA. Using a live cell biosensor, we demonstrate distinct roles for GEF-H1 and Ect2 in regulating Rho activity in the cleavage furrow, with GEF-H1 catalyzing Rho activation in response to Ect2-dependent localization and initiation of cell cleavage. Our results identify a GEF-H1-dependent mechanism to modulate localized RhoA activation during cytokinesis under the control of mitotic kinases.

    Funded by: NIGMS NIH HHS: GM 39424, R01 GM039434, U54 GM064346

    Developmental cell 2007;12;5;699-712

  • Large-scale mapping of human protein-protein interactions by mass spectrometry.

    Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T and Figeys D

    Protana, Toronto, Ontario, Canada.

    Mapping protein-protein interactions is an invaluable tool for understanding protein function. Here, we report the first large-scale study of protein-protein interactions in human cells using a mass spectrometry-based approach. The study maps protein interactions for 338 bait proteins that were selected based on known or suspected disease and functional associations. Large-scale immunoprecipitation of Flag-tagged versions of these proteins followed by LC-ESI-MS/MS analysis resulted in the identification of 24,540 potential protein interactions. False positives and redundant hits were filtered out using empirical criteria and a calculated interaction confidence score, producing a data set of 6463 interactions between 2235 distinct proteins. This data set was further cross-validated using previously published and predicted human protein interactions. In-depth mining of the data set shows that it represents a valuable source of novel protein-protein interactions with relevance to human diseases. In addition, via our preliminary analysis, we report many novel protein interactions and pathway associations.

    Molecular systems biology 2007;3;89

  • A probability-based approach for high-throughput protein phosphorylation analysis and site localization.

    Beausoleil SA, Villén J, Gerber SA, Rush J and Gygi SP

    Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, Massachusetts 02115, USA.

    Data analysis and interpretation remain major logistical challenges when attempting to identify large numbers of protein phosphorylation sites by nanoscale reverse-phase liquid chromatography/tandem mass spectrometry (LC-MS/MS) (Supplementary Figure 1 online). In this report we address challenges that are often only addressable by laborious manual validation, including data set error, data set sensitivity and phosphorylation site localization. We provide a large-scale phosphorylation data set with a measured error rate as determined by the target-decoy approach, we demonstrate an approach to maximize data set sensitivity by efficiently distracting incorrect peptide spectral matches (PSMs), and we present a probability-based score, the Ascore, that measures the probability of correct phosphorylation site localization based on the presence and intensity of site-determining ions in MS/MS spectra. We applied our methods in a fully automated fashion to nocodazole-arrested HeLa cell lysate where we identified 1,761 nonredundant phosphorylation sites from 491 proteins with a peptide false-positive rate of 1.3%.

    Funded by: NHGRI NIH HHS: HG03456; NIGMS NIH HHS: GM67945

    Nature biotechnology 2006;24;10;1285-92

  • Mutant p53 induces the GEF-H1 oncogene, a guanine nucleotide exchange factor-H1 for RhoA, resulting in accelerated cell proliferation in tumor cells.

    Mizuarai S, Yamanaka K and Kotani H

    Functional Genomics, Banyu Tsukuba Research Institute, Merck Research Laboratory, Tsukuba, Ibaraki, Japan.

    The tumor suppressor gene p53 is known to induce G1-S and G2-M cell cycle arrest and apoptosis by transactivating various wild-type (WT) p53 regulatory genes. Mutational inactivation of p53 is detected in more than half of human cancers, depriving the p53 protein of its tumor-suppressive functions. Recent studies have shown that mutant p53 provides tumor cells with gain-of-function properties, such as accelerated cell proliferation, increased metastasis, and apoptosis resistance. However, the mechanism underlying the elevated tumorigenicity by p53 mutation remains to be elucidated. In the present study, we showed that GEF-H1, a guanine exchange factor-H1 for RhoA, is transcriptionally activated by the induction of mutant p53 proteins, thereby accelerating tumor cell proliferation. Osteosarcoma U2OS cell lines, which express inducible p53 mutants (V157F, R175H, and R248Q), were established, and the expression profiles of each cell line were then analyzed to detect genes specifically induced by mutant p53. We identified GEF-H1 as one of the consensus genes whose expression was significantly induced by the three mutants. The GEF-H1 expression level strongly correlated with p53 status in a panel of 32 cancer cell lines, and GEF-H1 induction caused activation of RhoA. Furthermore, growth of mutant p53 cells was dependent on GEF-H1 expression, whereas that of WT p53 cells was not. These results suggest that increased GEF-H1 expression contributes to the tumor progression phenotype associated with the p53 mutation.

    Cancer research 2006;66;12;6319-26

  • Phosphoproteome analysis of the human mitotic spindle.

    Nousiainen M, Silljé HH, Sauer G, Nigg EA and Körner R

    Department of Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.

    During cell division, the mitotic spindle segregates the sister chromatids into two nascent cells, such that each daughter cell inherits one complete set of chromosomes. Errors in spindle formation can result in both chromosome missegregation and cytokinesis defects and hence lead to genomic instability. To ensure the correct function of the spindle, the activity and localization of spindle associated proteins has to be tightly regulated in time and space. Reversible phosphorylation has been shown to be one of the key regulatory mechanisms for the organization of the mitotic spindle. The relatively low number of identified in vivo phosphorylation sites of spindle components, however, has hampered functional analysis of regulatory spindle networks. A more complete inventory of the phosphorylation sites of spindle-associated proteins would therefore constitute an important advance. Here, we describe the mass spectrometry-based identification of in vivo phosphorylation sites from purified human mitotic spindles. In total, 736 phosphorylation sites were identified, of which 312 could be attributed to known spindle proteins. Among these are phosphorylation sites that were previously shown to be important for the regulation of spindle-associated proteins. Importantly, this data set also comprises 279 novel phosphorylation sites of known spindle proteins for future functional studies. This inventory of spindle phosphorylation sites should thus make an important contribution to a better understanding of the molecular mechanisms that regulate the formation, function, and integrity of the mitotic spindle.

    Proceedings of the National Academy of Sciences of the United States of America 2006;103;14;5391-6

  • The LIFEdb database in 2006.

    Mehrle A, Rosenfelder H, Schupp I, del Val C, Arlt D, Hahne F, Bechtel S, Simpson J, Hofmann O, Hide W, Glatting KH, Huber W, Pepperkok R, Poustka A and Wiemann S

    Division Molecular Genome Analysis, German Cancer Research Center, Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany. a.mehrle@dkfz.de

    LIFEdb (http://www.LIFEdb.de) integrates data from large-scale functional genomics assays and manual cDNA annotation with bioinformatics gene expression and protein analysis. New features of LIFEdb include (i) an updated user interface with enhanced query capabilities, (ii) a configurable output table and the option to download search results in XML, (iii) the integration of data from cell-based screening assays addressing the influence of protein-overexpression on cell proliferation and (iv) the display of the relative expression ('Electronic Northern') of the genes under investigation using curated gene expression ontology information. LIFEdb enables researchers to systematically select and characterize genes and proteins of interest, and presents data and information via its user-friendly web-based interface.

    Nucleic acids research 2006;34;Database issue;D415-8

  • Towards a proteome-scale map of the human protein-protein interaction network.

    Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP and Vidal M

    Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, Massachusetts 02115, USA.

    Systematic mapping of protein-protein interactions, or 'interactome' mapping, was initiated in model organisms, starting with defined biological processes and then expanding to the scale of the proteome. Although far from complete, such maps have revealed global topological and dynamic features of interactome networks that relate to known biological properties, suggesting that a human interactome map will provide insight into development and disease mechanisms at a systems level. Here we describe an initial version of a proteome-scale map of human binary protein-protein interactions. Using a stringent, high-throughput yeast two-hybrid system, we tested pairwise interactions among the products of approximately 8,100 currently available Gateway-cloned open reading frames and detected approximately 2,800 interactions. This data set, called CCSB-HI1, has a verification rate of approximately 78% as revealed by an independent co-affinity purification assay, and correlates significantly with other biological attributes. The CCSB-HI1 data set increases by approximately 70% the set of available binary interactions within the tested space and reveals more than 300 new connections to over 100 disease-associated proteins. This work represents an important step towards a systematic and comprehensive human interactome project.

    Funded by: NCI NIH HHS: R33 CA132073; NHGRI NIH HHS: P50 HG004233, R01 HG001715, RC4 HG006066, U01 HG001715; NHLBI NIH HHS: U01 HL098166

    Nature 2005;437;7062;1173-8

  • PAK4 mediates morphological changes through the regulation of GEF-H1.

    Callow MG, Zozulya S, Gishizky ML, Jallal B and Smeal T

    SUGEN Incorporated, 230 East Grand Avenue, South San Francisco, CA 94080, USA.

    Precise spatial and temporal regulation of Rho GTPases is required in controlling F-actin-based changes in cell morphology. The molecular mechanisms through which microtubules (MTs) modulate the activity of RhoGTPases and regulate the actin cytoskeleton are unclear. Here we show that p21-activated-kinase 4 (PAK4) mediates morphological changes through its association with the Rho-family guanine nucleotide exchange factor (GEF), GEF-H1. We show that this association is dependent upon a novel GEF-H1 interaction domain (GID) within PAK4. Further, we show that PAK4-mediated phosphorylation of Ser810 acts as a switch to block GEF-H1-dependent stress fiber formation while promoting the formation of lamellipodia in NIH-3T3 cells. We found that the endogenous PAK4-GEF-H1 complex associates with MTs and that PAK4 phosphorylation of MT-bound GEF-H1 releases it into the cytoplasm of NIH-3T3 cells, which coincides with the dissolution of stress fibers. Our observations propose a novel role for PAK4 in GEF-H1-dependent crosstalk between MTs and the actin cytoskeleton.

    Journal of cell science 2005;118;Pt 9;1861-72

  • Binding of GEF-H1 to the tight junction-associated adaptor cingulin results in inhibition of Rho signaling and G1/S phase transition.

    Aijaz S, D'Atri F, Citi S, Balda MS and Matter K

    Division of Cell Biology, Institute of Ophthalmology, University College London, UK.

    The activity of Rho GTPases is carefully timed to control epithelial proliferation and differentiation. RhoA is downregulated when epithelial cells reach confluence, resulting in inhibition of signaling pathways that stimulate proliferation. Here we show that GEF-H1/Lfc, a guanine nucleotide exchange factor for RhoA, directly interacts with cingulin, a junctional adaptor. Cingulin binding inhibits RhoA activation and signaling, suggesting that the increase in cingulin expression in confluent cells causes downregulation of RhoA by inhibiting GEF-H1/Lfc. In agreement, RNA interference of GEF-H1 or transfection of GEF-H1 binding cingulin mutants inhibit G1/S phase transition of MDCK cells, and depletion of cingulin by regulated RNA interference results in irregular monolayers and RhoA activation. These results indicate that forming epithelial tight junctions contribute to the downregulation of RhoA in epithelia by inactivating GEF-H1 in a cingulin-dependent manner, providing a molecular mechanism whereby tight junction formation is linked to inhibition of RhoA signaling.

    Developmental cell 2005;8;5;777-86

  • From ORFeome to biology: a functional genomics pipeline.

    Wiemann S, Arlt D, Huber W, Wellenreuther R, Schleeger S, Mehrle A, Bechtel S, Sauermann M, Korf U, Pepperkok R, Sültmann H and Poustka A

    Molecular Genome Analysis, German Cancer Research Center, 69120 Heidelberg, Germany. s.wiemann@dkfz.de

    As several model genomes have been sequenced, the elucidation of protein function is the next challenge toward the understanding of biological processes in health and disease. We have generated a human ORFeome resource and established a functional genomics and proteomics analysis pipeline to address the major topics in the post-genome-sequencing era: the identification of human genes and splice forms, and the determination of protein localization, activity, and interaction. Combined with the understanding of when and where gene products are expressed in normal and diseased conditions, we create information that is essential for understanding the interplay of genes and proteins in the complex biological network. We have implemented bioinformatics tools and databases that are suitable to store, analyze, and integrate the different types of data from high-throughput experiments and to include further annotation that is based on external information. All information is presented in a Web database (http://www.dkfz.de/LIFEdb). It is exploited for the identification of disease-relevant genes and proteins for diagnosis and therapy.

    Genome research 2004;14;10B;2136-44

  • Proteomic, functional, and domain-based analysis of in vivo 14-3-3 binding proteins involved in cytoskeletal regulation and cellular organization.

    Jin J, Smith FD, Stark C, Wells CD, Fawcett JP, Kulkarni S, Metalnikov P, O'Donnell P, Taylor P, Taylor L, Zougman A, Woodgett JR, Langeberg LK, Scott JD and Pawson T

    Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada.

    Background: 14-3-3 proteins are abundant and conserved polypeptides that mediate the cellular effects of basophilic protein kinases through their ability to bind specific peptide motifs phosphorylated on serine or threonine.

    Results: We have used mass spectrometry to analyze proteins that associate with 14-3-3 isoforms in HEK293 cells. This identified 170 unique 14-3-3-associated proteins, which show only modest overlap with previous 14-3-3 binding partners isolated by affinity chromatography. To explore this large set of proteins, we developed a domain-based hierarchical clustering technique that distinguishes structurally and functionally related subsets of 14-3-3 target proteins. This analysis revealed a large group of 14-3-3 binding partners that regulate cytoskeletal architecture. Inhibition of 14-3-3 phosphoprotein recognition in vivo indicates the general importance of such interactions in cellular morphology and membrane dynamics. Using tandem proteomic and biochemical approaches, we identify a phospho-dependent 14-3-3 binding site on the A kinase anchoring protein (AKAP)-Lbc, a guanine nucleotide exchange factor (GEF) for the Rho GTPase. 14-3-3 binding to AKAP-Lbc, induced by PKA, suppresses Rho activation in vivo.

    Conclusion: 14-3-3 proteins can potentially engage around 0.6% of the human proteome. Domain-based clustering has identified specific subsets of 14-3-3 targets, including numerous proteins involved in the dynamic control of cell architecture. This notion has been validated by the broad inhibition of 14-3-3 phosphorylation-dependent binding in vivo and by the specific analysis of AKAP-Lbc, a RhoGEF that is controlled by its interaction with 14-3-3.

    Funded by: NIDDK NIH HHS: DK44239

    Current biology : CB 2004;14;16;1436-50

  • Large-scale characterization of HeLa cell nuclear phosphoproteins.

    Beausoleil SA, Jedrychowski M, Schwartz D, Elias JE, Villén J, Li J, Cohn MA, Cantley LC and Gygi SP

    Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.

    Determining the site of a regulatory phosphorylation event is often essential for elucidating specific kinase-substrate relationships, providing a handle for understanding essential signaling pathways and ultimately allowing insights into numerous disease pathologies. Despite intense research efforts to elucidate mechanisms of protein phosphorylation regulation, efficient, large-scale identification and characterization of phosphorylation sites remains an unsolved problem. In this report we describe an application of existing technology for the isolation and identification of phosphorylation sites. By using a strategy based on strong cation exchange chromatography, phosphopeptides were enriched from the nuclear fraction of HeLa cell lysate. From 967 proteins, 2,002 phosphorylation sites were determined by tandem MS. This unprecedented large collection of sites permitted a detailed accounting of known and unknown kinase motifs and substrates.

    Funded by: NHGRI NIH HHS: HG00041, K22 HG000041, T32 HG000041; NIGMS NIH HHS: GM67945, GMS6203, R01 GM056203, R01 GM067945

    Proceedings of the National Academy of Sciences of the United States of America 2004;101;33;12130-5

  • Transcriptome characterization elucidates signaling networks that control human ES cell growth and differentiation.

    Brandenberger R, Wei H, Zhang S, Lei S, Murage J, Fisk GJ, Li Y, Xu C, Fang R, Guegler K, Rao MS, Mandalam R, Lebkowski J and Stanton LW

    Geron Corporation, Menlo Park, California 94025, USA. rbrandenberger@geron.com

    Human embryonic stem (hES) cells hold promise for generating an unlimited supply of cells for replacement therapies. To characterize hES cells at the molecular level, we obtained 148,453 expressed sequence tags (ESTs) from undifferentiated hES cells and three differentiated derivative subpopulations. Over 32,000 different transcripts expressed in hES cells were identified, of which more than 16,000 do not match closely any gene in the UniGene public database. Queries to this EST database revealed 532 significantly upregulated and 140 significantly downregulated genes in undifferentiated hES cells. These data highlight changes in the transcriptional network that occur when hES cells differentiate. Among the differentially regulated genes are several components of signaling pathways and transcriptional regulators that likely play key roles in hES cell growth and differentiation. The genomic data presented here may facilitate the derivation of clinically useful cell types from hES cells.

    Nature biotechnology 2004;22;6;707-16

  • p21-activated kinase 1 phosphorylates and regulates 14-3-3 binding to GEF-H1, a microtubule-localized Rho exchange factor.

    Zenke FT, Krendel M, DerMardirossian C, King CC, Bohl BP and Bokoch GM

    Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.

    GEF-H1 is a guanine nucleotide exchange factor for Rho whose activity is regulated through a cycle of microtubule binding and release. Here we identify a region in the carboxyl terminus of GEF-H1 that is important for suppression of its guanine nucleotide exchange activity by microtubules. This portion of the protein includes a coiled-coil motif, a proline-rich motif that may interact with Src homology 3 domain-containing proteins, and a potential binding site for 14-3-3 proteins. We identify GEF-H1 as a binding target and substrate for p21-activated kinase 1 (PAK1), an effector of Rac and Cdc42 GTPases, using an affinity-based screen and localize a PAK1 phosphorylation site to the inhibitory carboxyl-terminal region of GEF-H1. We show that phosphorylation of GEF-H1 at Ser(885) by PAK1 induces 14-3-3 binding to the exchange factor and relocation of 14-3-3 to microtubules. Phosphorylation of GEF-H1 by PAK may be involved in regulation of GEF-H1 activity and may serve to coordinate Rho-, Rac-, and Cdc42-mediated signaling pathways.

    The Journal of biological chemistry 2004;279;18;18392-400

  • Comprehensive proteomic analysis of human Par protein complexes reveals an interconnected protein network.

    Brajenovic M, Joberty G, Küster B, Bouwmeester T and Drewes G

    Cellzome AG, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.

    The polarization of eukaryotic cells is controlled by the concerted activities of asymmetrically localized proteins. The PAR proteins, first identified in Caenorhabditis elegans, are common regulators of cell polarity conserved from nematode and flies to man. However, little is known about the molecular mechanisms by which these proteins and protein complexes establish cell polarity in mammals. We have mapped multiprotein complexes formed around the putative human Par orthologs MARK4 (microtubule-associated protein/microtubule affinity-regulating kinase 4) (Par-1), Par-3, LKB1 (Par-4), 14-3-3zeta and eta (Par-5), Par-6a, -b, -c, and PKClambda (PKC3). We employed a proteomic approach comprising tandem affinity purification (TAP) of protein complexes from cultured cells and protein sequencing by tandem mass spectrometry. From these data we constructed a highly interconnected protein network consisting of three core complex "modules" formed around MARK4 (Par-1), Par-3.Par-6, and LKB1 (Par-4). The network confirms most previously reported interactions. In addition we identified more than 50 novel interactors, some of which, like the 14-3-3 phospho-protein scaffolds, occur in more than one distinct complex. We demonstrate that the complex formation between LKB1.Par-4, PAPK, and Mo25 results in the translocation of LKB1 from the nucleus to the cytoplasm and to tight junctions and show that the LKB1 complex may activate MARKs, which are known to introduce 14-3-3 binding sites into several substrates. Our findings suggest co-regulation and/or signaling events between the distinct Par complexes and provide a basis for further elucidation of the molecular mechanisms that govern cell polarity.

    The Journal of biological chemistry 2004;279;13;12804-11

  • A physical and functional map of the human TNF-alpha/NF-kappa B signal transduction pathway.

    Bouwmeester T, Bauch A, Ruffner H, Angrand PO, Bergamini G, Croughton K, Cruciat C, Eberhard D, Gagneur J, Ghidelli S, Hopf C, Huhse B, Mangano R, Michon AM, Schirle M, Schlegl J, Schwab M, Stein MA, Bauer A, Casari G, Drewes G, Gavin AC, Jackson DB, Joberty G, Neubauer G, Rick J, Kuster B and Superti-Furga G

    Cellzome AG, Meyerhofstrasse 1, 69117 Heidelberg, Germany. tewis.bouwmeester@cellzome.com

    Signal transduction pathways are modular composites of functionally interdependent sets of proteins that act in a coordinated fashion to transform environmental information into a phenotypic response. The pro-inflammatory cytokine tumour necrosis factor (TNF)-alpha triggers a signalling cascade, converging on the activation of the transcription factor NF-kappa B, which forms the basis for numerous physiological and pathological processes. Here we report the mapping of a protein interaction network around 32 known and candidate TNF-alpha/NF-kappa B pathway components by using an integrated approach comprising tandem affinity purification, liquid-chromatography tandem mass spectrometry, network analysis and directed functional perturbation studies using RNA interference. We identified 221 molecular associations and 80 previously unknown interactors, including 10 new functional modulators of the pathway. This systems approach provides significant insight into the logic of the TNF-alpha/NF-kappa B pathway and is generally applicable to other pathways relevant to human disease.

    Nature cell biology 2004;6;2;97-105

  • Complete sequencing and characterization of 21,243 full-length human cDNAs.

    Ota T, Suzuki Y, Nishikawa T, Otsuki T, Sugiyama T, Irie R, Wakamatsu A, Hayashi K, Sato H, Nagai K, Kimura K, Makita H, Sekine M, Obayashi M, Nishi T, Shibahara T, Tanaka T, Ishii S, Yamamoto J, Saito K, Kawai Y, Isono Y, Nakamura Y, Nagahari K, Murakami K, Yasuda T, Iwayanagi T, Wagatsuma M, Shiratori A, Sudo H, Hosoiri T, Kaku Y, Kodaira H, Kondo H, Sugawara M, Takahashi M, Kanda K, Yokoi T, Furuya T, Kikkawa E, Omura Y, Abe K, Kamihara K, Katsuta N, Sato K, Tanikawa M, Yamazaki M, Ninomiya K, Ishibashi T, Yamashita H, Murakawa K, Fujimori K, Tanai H, Kimata M, Watanabe M, Hiraoka S, Chiba Y, Ishida S, Ono Y, Takiguchi S, Watanabe S, Yosida M, Hotuta T, Kusano J, Kanehori K, Takahashi-Fujii A, Hara H, Tanase TO, Nomura Y, Togiya S, Komai F, Hara R, Takeuchi K, Arita M, Imose N, Musashino K, Yuuki H, Oshima A, Sasaki N, Aotsuka S, Yoshikawa Y, Matsunawa H, Ichihara T, Shiohata N, Sano S, Moriya S, Momiyama H, Satoh N, Takami S, Terashima Y, Suzuki O, Nakagawa S, Senoh A, Mizoguchi H, Goto Y, Shimizu F, Wakebe H, Hishigaki H, Watanabe T, Sugiyama A, Takemoto M, Kawakami B, Yamazaki M, Watanabe K, Kumagai A, Itakura S, Fukuzumi Y, Fujimori Y, Komiyama M, Tashiro H, Tanigami A, Fujiwara T, Ono T, Yamada K, Fujii Y, Ozaki K, Hirao M, Ohmori Y, Kawabata A, Hikiji T, Kobatake N, Inagaki H, Ikema Y, Okamoto S, Okitani R, Kawakami T, Noguchi S, Itoh T, Shigeta K, Senba T, Matsumura K, Nakajima Y, Mizuno T, Morinaga M, Sasaki M, Togashi T, Oyama M, Hata H, Watanabe M, Komatsu T, Mizushima-Sugano J, Satoh T, Shirai Y, Takahashi Y, Nakagawa K, Okumura K, Nagase T, Nomura N, Kikuchi H, Masuho Y, Yamashita R, Nakai K, Yada T, Nakamura Y, Ohara O, Isogai T and Sugano S

    Helix Research Institute, 1532-3 Yana, Kisarazu, Chiba 292-0812, Japan.

    As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.

    Nature genetics 2004;36;1;40-5

  • Ten years on: mediation of cell death by the common neurotrophin receptor p75(NTR).

    Rabizadeh S and Bredesen DE

    The Buck Institute for Age Research, 8001 Redwood Blvd, Novato, CA 94945-1400, USA. srabizadeh@buckinstitute.org

    The common neurotrophin receptor p75(NTR) remains one of the most enigmatic of the tumor necrosis factor receptor (TNFR) superfamily: on the one hand, it displays a death domain and has been shown to be capable of mediating programmed cell death (PCD) upon ligand binding; on the other hand, its death domain is of type II (unlike that of Fas or TNFR I), and it has also been shown to be capable of mediating cell death in response to the withdrawal of ligand. Thus, p75(NTR) may function as a death receptor-similar to Fas or TNFR I-or a dependence receptor-similar to deleted in colorectal cancer (DCC) or uncoordinated gene-5 homologues 1-3 (UNC5H1-3). Here, we review the data relating to the mediation of PCD by p75(NTR), and suggest that one reasonable model for the apparently paradoxical effects of p75(NTR) is that this receptor functions as a "quality control" in that it is capable of mediating PCD in at least four situations: (1). withdrawal of neurotrophins; (2). exposure to mismatched neurotrophins; (3). exposure to unprocessed neurotrophins; and (4). exposure of inappropriately immature cells to neurotrophins. Results to date suggest that these functions are mediated through different underlying mechanisms, and that their respective signaling pathways are cell type and co-receptor dependent.

    Cytokine & growth factor reviews 2003;14;3-4;225-39

  • NRAGE, a p75 neurotrophin receptor-interacting protein, induces caspase activation and cell death through a JNK-dependent mitochondrial pathway.

    Salehi AH, Xanthoudakis S and Barker PA

    Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, 3801 University Avenue, Montreal, Quebec H3A 2B4, Canada.

    The p75 neurotrophin receptor (p75NTR) mediates signaling events leading to activation of the JNK pathway and cell death in a variety of cell types. We recently identified NRAGE, a protein that directly interacts with the p75NTR cytosolic region and facilitates p75NTR-mediated cell death. For the present study, we developed an inducible recombinant NRAGE adenovirus to dissect the mechanism of NRAGE-mediated apoptosis. Induced NRAGE expression resulted in robust activation of the JNK pathway that was not inhibited by the pharmacological mixed lineage kinase (MLK) inhibitor CEP1347. NRAGE induced cytosolic accumulation of cytochrome c, activation of Caspases-3, -9 and -7, and caspase-dependent cell death. Blocking JNK and c-Jun action by overexpression of the JNK-binding domain of JIP1 or dominant-negative c-Jun ablated NRAGE-mediated caspase activation and NRAGE-induced cell death. These findings identify NRAGE as a p75NTR interactor capable of inducing caspase activation and cell death through a JNK-dependent mitochondrial apoptotic pathway.

    The Journal of biological chemistry 2002;277;50;48043-50

  • Ras and relatives--job sharing and networking keep an old family together.

    Ehrhardt A, Ehrhardt GR, Guo X and Schrader JW

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

    Many members of the Ras superfamily of GTPases have been implicated in the regulation of hematopoietic cells, with roles in growth, survival, differentiation, cytokine production, chemotaxis, vesicle-trafficking, and phagocytosis. The well-known p21 Ras proteins H-Ras, N-Ras, K-Ras 4A, and K-Ras 4B are also frequently mutated in human cancer and leukemia. Besides the four p21 Ras proteins, the Ras subfamily of the Ras superfamily includes R-Ras, TC21 (R-Ras2), M-Ras (R-Ras3), Rap1A, Rap1B, Rap2A, Rap2B, RalA, and RalB. They exhibit remarkable overall amino acid identities, especially in the regions interacting with the guanine nucleotide exchange factors that catalyze their activation. In addition, there is considerable sharing of various downstream effectors through which they transmit signals and of GTPase activating proteins that downregulate their activity, resulting in overlap in their regulation and effector function. Relatively little is known about the physiological functions of individual Ras family members, although the presence of well-conserved orthologs in Caenorhabditis elegans suggests that their individual roles are both specific and vital. The structural and functional similarities have meant that commonly used research tools fail to discriminate between the different family members, and functions previously attributed to one family member may be shared with other members of the Ras family. Here we discuss similarities and differences in activation, effector usage, and functions of different members of the Ras subfamily. We also review the possibility that the differential localization of Ras proteins in different parts of the cell membrane may govern their responses to activation of cell surface receptors.

    Experimental hematology 2002;30;10;1089-106

  • Nucleotide exchange factor GEF-H1 mediates cross-talk between microtubules and the actin cytoskeleton.

    Krendel M, Zenke FT and Bokoch GM

    Department of Immunology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA.

    Regulation of the actin cytoskeleton by microtubules is mediated by the Rho family GTPases. However, the molecular mechanisms that link microtubule dynamics to Rho GTPases have not, as yet, been identified. Here we show that the Rho guanine nucleotide exchange factor (GEF)-H1 is regulated by an interaction with microtubules. GEF-H1 mutants that are deficient in microtubule binding have higher activity levels than microtubule-bound forms. These mutants also induce Rho-dependent changes in cell morphology and actin organization. Furthermore, drug-induced microtubule depolymerization induces changes in cell morphology and gene expression that are similar to the changes induced by the expression of active forms of GEF-H1. Furthermore, these effects are inhibited by dominant-negative versions of GEF-H1. Thus, GEF-H1 links changes in microtubule integrity to Rho-dependent regulation of the actin cytoskeleton.

    Funded by: NIGMS NIH HHS: GM34934

    Nature cell biology 2002;4;4;294-301

  • Activation of Rac GTPase by p75 is necessary for c-jun N-terminal kinase-mediated apoptosis.

    Harrington AW, Kim JY and Yoon SO

    Neurobiotech Center and Department of Neuroscience, Ohio State University, Columbus, Ohio 43210, USA.

    The neurotrophin receptor p75 can induce apoptosis both in vitro and in vivo. The mechanisms by which p75 induces apoptosis have remained mostly unknown. Here, we report that p75 activates Rac GTPase, which in turn activates c-jun N-terminal kinase (JNK), including an injury-specific JNK3, in an NGF-dependent manner. N17Rac blocks this JNK activation and subsequent NGF-dependent apoptosis, indicating that activation of Rac GTPase is required for JNK activation and apoptosis induced by p75. In addition, p75-mediated Rac activation is modulated by coactivation of Trk, identifying Rac GTPase as one of the key molecules whose activity is critical for cell survival and death in neurotrophin signaling. The crucial role of the JNK pathway in p75 signaling is further confirmed by the results that blocking p75 from signaling via the JNK pathway or suppressing the JNK activity itself led to inhibition of NGF-dependent death. Together, these results indicate that the apoptotic machinery of p75 comprises Rac GTPase and JNK.

    Funded by: NINDS NIH HHS: R01 NS39472-01

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2002;22;1;156-66

  • Trp(56) of rac1 specifies interaction with a subset of guanine nucleotide exchange factors.

    Gao Y, Xing J, Streuli M, Leto TL and Zheng Y

    Department of Molecular Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA.

    Signaling specificity of Rho GTPase pathways is achieved in part by selective interaction between members of the Dbl family guanine nucleotide exchange factors (GEFs) and their Rho GTPase substrates. For example, Trio, GEF-H1, and Tiam1 are a subset of GEFs that specifically activate Rac1 but not the closely related Cdc42. The Rac1 specificity of these GEFs appears to be governed by Rac1-GEF binding interaction. To understand the detailed mechanism underlying the GEF specificity issue, we have analyzed a panel of chimeras made between Rac1 and Cdc42 and examined a series of point mutants of Rac1 made at the switch I, switch II, and beta(2)/beta(3) regions for their ability to interact with and to be activated by the GEFs. The results reveal that Rac1 residues of both the switch I and switch II regions are involved in GEF docking and GEF-mediated nucleotide disruption, because mutation of Asp(38), Asn(39), Gln(61), Tyr(64), or Arg(66)/Leu(67) into Ala results in the loss of GEF binding, whereas mutation at Tyr(32), Asp(65), or Leu(70)/Ser(71) leads to the loss of GEF catalysis while retaining the binding capability. The region between amino acids 53-72 of Rac1 is required for specific recognition and activation by the GEFs, and Trp(56) in beta(3) appears to be the critical determinant. Introduction of Trp(56) to Cdc42 renders it fully responsive to the Rac-specific GEF in vitro and in cells. Further, a polypeptide derived from the beta(3) region of Rac1 including the Trp(56) residue serves as a specific inhibitor for Rac1 interaction with the GEFs. Taken together, these results indicate that Trp(56) is the necessary and sufficient determinant of Rac1 for discrimination by the subset of Rac1-specific GEFs and suggest that a compound mimicking Trp(56) action could be explored as an interfering reagent specifically targeting Rac1 activation.

    Funded by: NIGMS NIH HHS: GM 53943, GM 60523

    The Journal of biological chemistry 2001;276;50;47530-41

  • Toward a catalog of human genes and proteins: sequencing and analysis of 500 novel complete protein coding human cDNAs.

    Wiemann S, Weil B, Wellenreuther R, Gassenhuber J, Glassl S, Ansorge W, Böcher M, Blöcker H, Bauersachs S, Blum H, Lauber J, Düsterhöft A, Beyer A, Köhrer K, Strack N, Mewes HW, Ottenwälder B, Obermaier B, Tampe J, Heubner D, Wambutt R, Korn B, Klein M and Poustka A

    Molecular Genome Analysis, German Cancer Research Center, 69120 Heidelberg, Germany. s.wiemann@dkfz.de

    With the complete human genomic sequence being unraveled, the focus will shift to gene identification and to the functional analysis of gene products. The generation of a set of cDNAs, both sequences and physical clones, which contains the complete and noninterrupted protein coding regions of all human genes will provide the indispensable tools for the systematic and comprehensive analysis of protein function to eventually understand the molecular basis of man. Here we report the sequencing and analysis of 500 novel human cDNAs containing the complete protein coding frame. Assignment to functional categories was possible for 52% (259) of the encoded proteins, the remaining fraction having no similarities with known proteins. By aligning the cDNA sequences with the sequences of the finished chromosomes 21 and 22 we identified a number of genes that either had been completely missed in the analysis of the genomic sequences or had been wrongly predicted. Three of these genes appear to be present in several copies. We conclude that full-length cDNA sequencing continues to be crucial also for the accurate identification of genes. The set of 500 novel cDNAs, and another 1000 full-coding cDNAs of known transcripts we have identified, adds up to cDNA representations covering 2%--5 % of all human genes. We thus substantially contribute to the generation of a gene catalog, consisting of both full-coding cDNA sequences and clones, which should be made freely available and will become an invaluable tool for detailed functional studies.

    Genome research 2001;11;3;422-35

  • DNA cloning using in vitro site-specific recombination.

    Hartley JL, Temple GF and Brasch MA

    Life Technologies, Inc., Rockville, Maryland 20850, USA. jhartley@lifetech.com

    As a result of numerous genome sequencing projects, large numbers of candidate open reading frames are being identified, many of which have no known function. Analysis of these genes typically involves the transfer of DNA segments into a variety of vector backgrounds for protein expression and functional analysis. We describe a method called recombinational cloning that uses in vitro site-specific recombination to accomplish the directional cloning of PCR products and the subsequent automatic subcloning of the DNA segment into new vector backbones at high efficiency. Numerous DNA segments can be transferred in parallel into many different vector backgrounds, providing an approach to high-throughput, in-depth functional analysis of genes and rapid optimization of protein expression. The resulting subclones maintain orientation and reading frame register, allowing amino- and carboxy-terminal translation fusions to be generated. In this paper, we outline the concepts of this approach and provide several examples that highlight some of its potential.

    Genome research 2000;10;11;1788-95

  • Cloning and characterization of GEF-H1, a microtubule-associated guanine nucleotide exchange factor for Rac and Rho GTPases.

    Ren Y, Li R, Zheng Y and Busch H

    Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030, USA. yren@bcm.tmc.edu

    The Rho-related small GTPases are critical elements involved in regulation of signal transduction cascades from extracellular stimuli to cell nucleus and cytoskeleton. The Dbl-like guanine nucleotide exchange factors (GEF) have been implicated in direct activation of these GTPases. Here we have identified a new member of the Dbl family, GEF-H1, by screening a human HeLa cell cDNA library. GEF-H1 encodes a 100-kDa protein containing the conserved structural array of a Dbl homology domain in tandem with a pleckstrin homology domain and is most closely related to the lfc oncogene, but additionally it contains a unique coiled-coil domain at the carboxyl terminus. Biochemical analysis reveals that GEF-H1 is capable of stimulating guanine nucleotide exchange of Rac and Rho but is inactive toward Cdc42, TC10, or Ras. Moreover, GEF-H1 binds to Rac and Rho proteins in both the GDP- and guanosine 5'-3-O-(thio)triphosphate-bound states without detectable affinity for Cdc42 or Ras. Immunofluorescence reveals that GEF-H1 colocalizes with microtubules through the carboxyl-terminal coiled-coil domain. Overexpression of GEF-H1 in COS-7 cells results in induction of membrane ruffles. These results suggest that GEF-H1 may have a direct role in activation of Rac and/or Rho and in bringing the activated GTPase to specific target sites such as microtubules.

    Funded by: NIGMS NIH HHS: GM53943

    The Journal of biological chemistry 1998;273;52;34954-60

  • WAVE, a novel WASP-family protein involved in actin reorganization induced by Rac.

    Miki H, Suetsugu S and Takenawa T

    Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108, Japan.

    Rac is a Rho-family small GTPase that induces the formation of membrane ruffles. However, it is poorly understood how Rac-induced reorganization of the actin cytoskeleton, which is essential for ruffle formation, is regulated. Here we identify a novel Wiskott-Aldrich syndrome protein (WASP)-family protein, WASP family Verprolin-homologous protein (WAVE), as a regulator of actin reorganization downstream of Rac. Ectopically expressed WAVE induces the formation of actin filament clusters that overlap with the expressed WAVE itself. In this actin clustering, profilin, a monomeric actin-binding protein that has been suggested to be involved in actin polymerization, was shown to be essential. The expression of a dominant-active Rac mutant induces the translocation of endogenous WAVE from the cytosol to membrane ruffling areas. Furthermore, the co-expression of a deltaVPH WAVE mutant that cannot induce actin reorganization specifically suppresses the ruffle formation induced by Rac, but has no effect on Cdc42-induced actin-microspike formation, a phenomenon that is also known to be dependent on rapid actin reorganization. The deltaVPH WAVE also suppresses membrane-ruffling formation induced by platelet-derived growth factor in Swiss 3T3 cells. Taken together, we conclude that WAVE plays a critical role downstream of Rac in regulating the actin cytoskeleton required for membrane ruffling.

    The EMBO journal 1998;17;23;6932-41

  • Prediction of the coding sequences of unidentified human genes. X. The complete sequences of 100 new cDNA clones from brain which can code for large proteins in vitro.

    Ishikawa K, Nagase T, Suyama M, Miyajima N, Tanaka A, Kotani H, Nomura N and Ohara O

    Kazusa DNA Research Institute, Kisarazu, Chiba, Japan.

    As an extension of our cDNA analysis for deducing the coding sequences of unidentified human genes, we have newly determined the sequences of 100 cDNA clones from a set of size-fractionated human brain cDNA libraries, and predicted the coding sequences of the corresponding genes, named KIAA0611 to KIAA0710. In vitro transcription-coupled translation assay was applied as the first screening to select cDNA clones which produce proteins with apparent molecular mass of 50 kDa and over. One hundred unidentified cDNA clones thus selected were then subjected to sequencing of entire inserts. The average size of the inserts and corresponding open reading frames was 4.9 kb and 2.8 kb (922 amino acid residues), respectively. Computer search of the sequences against the public databases indicated that predicted coding sequences of 87 genes were similar to those of known genes, 62% of which (54 genes) were categorized as proteins related to cell signaling/communication, cell structure/motility and nucleic acid management. The expression profiles in 10 human tissues of all the clones characterized in this study were examined by reverse transcription-coupled polymerase chain reaction and the chromosomal locations of the clones were determined by using human-rodent hybrid panels.

    DNA research : an international journal for rapid publication of reports on genes and genomes 1998;5;3;169-76

  • Isolation and characterization of complementary DNA to proliferating cell nucleolar antigen P40.

    Reddy AB, Chatterjee A, Rothblum LI, Black A and Busch H

    Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030.

    Proliferating cell nucleolar antigen P40 is a late G1-specific protein, which was found in a variety of human tumors (A. Chatterjee, J. W. Freeman, and H. Busch. Cancer Res., 47: 1123-1129, 1987). Two overlapping complementary DNA clones for antigen P40 were isolated by immunoscreening a lambda gt11 human expression library. The complete nucleotide sequence of the clones was determined. The complementary DNAs encode the Mr 30,000 portion of the COOH-terminal portion of the protein. The mRNA for P40 was 2.8 kilobases long and was expressed maximally in G1 cells in cell cycle. A series of deletion mutants of the expressed peptide was constructed and the deletion mutants were expressed in Escherichia coli. Using these mutants, the epitope region of P40 recognized by a P40-specific monoclonal antibody was identified. The hydropathy plot based on the protein sequence revealed that this region of the protein is largely hydrophilic. This protein is unique and differs in sequence from other proliferating cell nuclear/nucleolar antigen proteins of similar molecular weight such as protein B23 and cyclin.

    Funded by: NCI NIH HHS: CA-10893, P1

    Cancer research 1989;49;7;1763-7

Gene lists (6)

Gene List Source Species Name Description Gene count
L00000009 G2C Homo sapiens Human PSD Human orthologues of mouse PSD adapted from Collins et al (2006) 1080
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000059 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus 748
L00000061 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus (ortho) 984
L00000069 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list 1461
L00000071 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list (ortho) 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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