G2Cdb::Gene report

Gene id
Gene symbol
Actn4 (MGI)
Mus musculus
actinin alpha 4
G00001793 (Homo sapiens)

Databases (9)

Curated Gene
OTTMUSG00000016983 (Vega mouse gene)
ENSMUSG00000054808 (Ensembl mouse gene)
60595 (Entrez Gene)
170 (G2Cdb plasticity & disease)
Gene Expression
NM_021895 (Allen Brain Atlas)
60595 (Genepaint)
604638 (OMIM)
Marker Symbol
MGI:1890773 (MGI)
Protein Sequence
P57780 (UniProt)

Literature (38)

Pubmed - other

  • 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

  • α-actinin-4 is essential for maintaining the spreading, motility and contractility of fibroblasts.

    Shao H, Wang JH, Pollak MR and Wells A

    Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

    Background: α-Actinins cross-link actin filaments, with this cross-linking activity regulating the formation of focal adhesions, intracellular tension, and cell migration. Most non-muscle cells such as fibroblasts express two isoforms, α-actinin-1 (ACTN1) and α-actinin-4 (ACTN4). The high homology between these two isoforms would suggest redundancy of their function, but recent studies have suggested different regulatory roles. Interestingly, ACTN4 is phosphorylated upon growth factor stimulation, and this loosens its interaction with actin.

    Using molecular, biochemical and cellular techniques, we probed the cellular functions of ACTN4 in fibroblasts. Knockdown of ACTN4 expression in murine lung fibroblasts significantly impaired cell migration, spreading, adhesion, and proliferation. Surprisingly, knockdown of ACTN4 enhanced cellular compaction and contraction force, and increased cellular and nuclear cross-sectional area. These results, except the increased contractility, are consistent with a putative role of ACTN4 in cytokinesis. For the transcellular tension, knockdown of ACTN4 significantly increased the expression of myosin light chain 2, a element of the contractility machinery. Re-expression of wild type human ACTN4 in ACTN4 knockdown murine lung fibroblasts reverted cell spreading, cellular and nuclear cross-sectional area, and contractility back towards baseline, demonstrating that the defect was due to absence of ACTN4.

    Significance: These results suggest that ACTN4 is essential for maintaining normal spreading, motility, cellular and nuclear cross-sectional area, and contractility of murine lung fibroblasts by maintaining the balance between transcellular contractility and cell-substratum adhesion.

    Funded by: NIDDK NIH HHS: R01 DK054931, R01DK054931; NIGMS NIH HHS: R01 GM069668, R01GM069668

    PloS one 2010;5;11;e13921

  • Molecular mechanisms underlying nucleocytoplasmic shuttling of actinin-4.

    Kumeta M, Yoshimura SH, Harata M and Takeyasu K

    Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan. kumeta@lif.kyoto-u.ac.jp

    In addition to its well-known role as a crosslinker of actin filaments at focal-adhesion sites, actinin-4 is known to be localized to the nucleus. In this study, we reveal the molecular mechanism underlying nuclear localization of actinin-4 and its novel interactions with transcriptional regulators. We found that actinin-4 is imported into the nucleus through the nuclear pore complex in an importin-independent manner and is exported by the chromosome region maintenance-1 (CRM1)-dependent pathway. Nuclear actinin-4 levels were significantly increased in the late G2 phase of the cell cycle and were decreased in the G1 phase, suggesting that active release from the actin cytoskeleton was responsible for increased nuclear actinin-4 in late G2. Nuclear actinin-4 was found to interact with the INO80 chromatin-remodeling complex. It also directs the expression of a subset of cell-cycle-related genes and interacts with the upstream-binding factor (UBF)-dependent rRNA transcriptional machinery in the M phase. These findings provide molecular mechanisms for both nucleocytoplasmic shuttling of proteins that do not contain a nuclear-localization signal and cell-cycle-dependent gene regulation that reflects morphological changes in the cytoskeleton.

    Journal of cell science 2010;123;Pt 7;1020-30

  • Glomerular epithelial cell injury associated with mutant alpha-actinin-4.

    Cybulsky AV, Takano T, Papillon J, Bijian K, Guillemette J and Kennedy CR

    Div. of Nephrology, Royal Victoria Hospital, 687 Pine Ave. West, Montreal, Quebec, Canada H3A1A1. andrey.cybulsky@mcgill.ca

    Focal segmental glomerulosclerosis (FSGS) may be associated with glomerular epithelial cell (GEC; podocyte) apoptosis due to acquired injury or mutations in alpha-actinin-4. This study addresses how FSGS-associated mutant alpha-actinin-4 may induce GEC injury, focusing on endoplasmic reticulum (ER) stress and metabolism of mutant alpha-actinin-4 via the ubiquitin-proteasome system. In a model of experimental FSGS induced by expression of an alpha-actinin-4 K256E transgene in podocytes, we show induction of ER stress, including upregulation of ER chaperones (bip, grp94), phosphorylation of the eukaryotic translation initiation factor-2alpha subunit, and induction of the proapoptotic gene C/EBP homologous protein-10 (CHOP). To address mechanisms of ER stress, we studied signaling in cultured GEC and COS cells expressing alpha-actinin-4 K256E. Previously, we showed that expression of this alpha-actinin-4 mutant in GEC increased apoptosis. In the present study, we show that alpha-actinin-4 K256E upregulates grp94 and CHOP expression in COS cells and significantly exacerbates induction of bip and CHOP in GEC in the presence of tunicamycin. ER stress was associated with aggregation and ubiquitination of alpha-actinin-4 K256E and impairment of the ubiquitin-proteasome system. In addition, alpha-actinin-4 K256E exacerbated apoptosis in the context of mild proteasome inhibition. Thus alpha-actinin-4 K256E triggers several metabolic abnormalities, which may lead to GEC injury and glomerulosclerosis.

    American journal of physiology. Renal physiology 2009;297;4;F987-95

  • A postnatal switch of CELF and MBNL proteins reprograms alternative splicing in the developing heart.

    Kalsotra A, Xiao X, Ward AJ, Castle JC, Johnson JM, Burge CB and Cooper TA

    Department of Pathology, Baylor College of Medicine, Houston, TX 77030, USA.

    From a large-scale screen using splicing microarrays and RT-PCR, we identified 63 alternative splicing (AS) events that are coordinated in 3 distinct temporal patterns during mouse heart development. More than half of these splicing transitions are evolutionarily conserved between mouse and chicken. Computational analysis of the introns flanking these splicing events identified enriched and conserved motifs including binding sites for CUGBP and ETR-3-like factors (CELF), muscleblind-like (MBNL) and Fox proteins. We show that CELF proteins are down-regulated >10-fold during heart development, and MBNL1 protein is concomitantly up-regulated nearly 4-fold. Using transgenic and knockout mice, we show that reproducing the embryonic expression patterns for CUGBP1 and MBNL1 in adult heart induces the embryonic splicing patterns for more than half of the developmentally regulated AS transitions. These findings indicate that CELF and MBNL proteins are determinative for a large subset of splicing transitions that occur during postnatal heart development.

    Funded by: NHGRI NIH HHS: HG002439, R01 HG002439; NHLBI NIH HHS: R01 HL045565, R01HL45565; NIGMS NIH HHS: R01 GM076493, R01GM076493

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;51;20333-8

  • Involvement of actinin-4 in the recruitment of JRAB/MICAL-L2 to cell-cell junctions and the formation of functional tight junctions.

    Nakatsuji H, Nishimura N, Yamamura R, Kanayama HO and Sasaki T

    Department of Biochemistry, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan.

    Tight junctions (TJs) are cell-cell adhesive structures that undergo continuous remodeling. We previously demonstrated that Rab13 and a junctional Rab13-binding protein (JRAB)/molecule interacting with CasL-like 2 (MICAL-L2) localized at TJs and mediated the endocytic recycling of the integral TJ protein occludin and the formation of functional TJs. Here, we investigated how JRAB/MICAL-L2 was targeted to TJs. Using a series of deletion mutants, we found the plasma membrane (PM)-targeting domain within JRAB/MICAL-L2. We then identified actinin-4, which was originally isolated as an actin-binding protein associated with cell motility and cancer invasion/metastasis, as a binding protein for the PM-targeting domain of JRAB/MICAL-L2, using a yeast two-hybrid system. Actinin-4 was colocalized with JRAB/MICAL-L2 at cell-cell junctions and linked JRAB/MICAL-L2 to F-actin. Although actinin-4 bound to JRAB/MICAL-L2 without Rab13, the actinin-4-JRAB/MICAL-L2 interaction was enhanced by Rab13 activation. Depletion of actinin-4 by using small interfering RNA inhibited the recruitment of occludin to TJs during the Ca(2+) switch. During the epithelial polarization after replating, JRAB/MICAL-L2 was recruited from the cytosol to cell-cell junctions. This JRAB/MICAL-L2 recruitment as well as the formation of functional TJs was delayed in actinin-4-depleted cells. These results indicate that actinin-4 is involved in recruiting JRAB/MICAL-L2 to cell-cell junctions and forming functional TJs.

    Molecular and cellular biology 2008;28;10;3324-35

  • Myeloid and lymphoid contribution to non-haematopoietic lineages through irradiation-induced heterotypic cell fusion.

    Nygren JM, Liuba K, Breitbach M, Stott S, Thorén L, Roell W, Geisen C, Sasse P, Kirik D, Björklund A, Nerlov C, Fleischmann BK, Jovinge S and Jacobsen SE

    Hematopoietic Stem Cell Laboratory, Lund University, BMC B10, Klinikgatan 26, 221 84 Lund, Sweden.

    Recent studies have suggested that regeneration of non-haematopoietic cell lineages can occur through heterotypic cell fusion with haematopoietic cells of the myeloid lineage. Here we show that lymphocytes also form heterotypic-fusion hybrids with cardiomyocytes, skeletal muscle, hepatocytes and Purkinje neurons. However, through lineage fate-mapping we demonstrate that such in vivo fusion of lymphoid and myeloid blood cells does not occur to an appreciable extent in steady-state adult tissues or during normal development. Rather, fusion of blood cells with different non-haematopoietic cell types is induced by organ-specific injuries or whole-body irradiation, which has been used in previous studies to condition recipients of bone marrow transplants. Our findings demonstrate that blood cells of the lymphoid and myeloid lineages contribute to various non-haematopoietic tissues by forming rare fusion hybrids, but almost exclusively in response to injuries or inflammation.

    Funded by: Medical Research Council: G0501838

    Nature cell biology 2008;10;5;584-92

  • Mice with altered alpha-actinin-4 expression have distinct morphologic patterns of glomerular disease.

    Henderson JM, Al-Waheeb S, Weins A, Dandapani SV and Pollak MR

    Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.

    Mutations in ACTN4, encoding the actin-binding protein alpha-actinin-4, cause a form of familial focal segmental glomerulosclerosis. We had developed two strains of transgenic mice with distinct alterations in the expression of alpha-actinin-4. One strain carried a human disease-associated mutation in murine Actn4, whereas the other knockout strain did not express alpha-actinin-4 protein. Most adult homozygous Actn4 mutant and knockout mice developed collapsing glomerulopathy. Homozygous Actn4 mutant mice also exhibited actin and alpha-actinin-4-containing electron-dense cytoplasmic structures, that were present but less prominent in heterozygous Actn4 mutant mice and not consistently seen in wild-type or knockout mice. Heterozygous Actn4 mutant mice did not develop glomerulosclerosis, but did exhibit focal glomerular hypertrophy and mild glomerular ultrastructural changes. The ultrastructural abnormalities seen in heterozygous Actn4 mutant mice suggest low-level glomerular damage, which may increase susceptibility to injury caused by genetic or environmental stressors. Our studies show that different genetic defects in the same protein produce a spectrum of glomerular morphologic lesions depending on the specific combination of normal and/or defective alleles.

    Funded by: NHLBI NIH HHS: T32 HL007627, T32HL07627; NIDDK NIH HHS: DK43351, DK57521, DK66017, F32 DK072625, F32DK72625, P30 DK043351, P30 DK057521, R01 DK059588, R01 DK059588-09, R01 DK066017

    Kidney international 2008;73;6;741-50

  • Disease-associated mutant alpha-actinin-4 reveals a mechanism for regulating its F-actin-binding affinity.

    Weins A, Schlondorff JS, Nakamura F, Denker BM, Hartwig JH, Stossel TP and Pollak MR

    Renal and Translational Medicine Divisions, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.

    Alpha-actinin-4 is a widely expressed protein that employs an actin-binding site with two calponin homology domains to crosslink actin filaments (F-actin) in a Ca(2+)-sensitive manner in vitro. An inherited, late-onset form of kidney failure is caused by point mutations in the alpha-actinin-4 actin-binding domain. Here we show that alpha-actinin-4/F-actin aggregates, observed in vivo in podocytes of humans and mice with disease, likely form as a direct result of the increased actin-binding affinity of the protein. We document that exposure of a buried actin-binding site 1 in mutant alpha-actinin-4 causes an increase in its actin-binding affinity, abolishes its Ca(2+) regulation in vitro, and diverts its normal localization from actin stress fibers and focal adhesions in vivo. Inactivation of this buried actin-binding site returns the affinity of the mutant to that of the WT protein and abolishes aggregate formation in cells. In vitro, actin filaments crosslinked by the mutant alpha-actinin-4 exhibit profound changes of structural and biomechanical properties compared with WT alpha-actinin-4. On a molecular level, our findings elucidate the physiological importance of a dynamic interaction of alpha-actinin with F-actin in podocytes in vivo. We propose that a conformational change with full exposure of actin-binding site 1 could function as a switch mechanism to regulate the actin-binding affinity of alpha-actinin and possibly other calponin homology domain proteins under physiological conditions.

    Funded by: NHLBI NIH HHS: HL19429, R01 HL019429; NIDDK NIH HHS: DK59588, F32 DK074308, F32-DK074308-01, R01 DK059588, R01 DK059588-09, R37 DK059588, T32 DK007527, T32-DK007527-20

    Proceedings of the National Academy of Sciences of the United States of America 2007;104;41;16080-5

  • EUCOMM--the European conditional mouse mutagenesis program.

    Friedel RH, Seisenberger C, Kaloff C and Wurst W

    GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.

    Functional analysis of the mammalian genome is an enormous challenge for biomedical scientists. To facilitate this endeavour, the European Conditional Mouse Mutagenesis Program (EUCOMM) aims at generating up to 12 000 mutations by gene trapping and up to 8000 mutations by gene targeting in mouse embryonic stem (ES) cells. These mutations can be rendered into conditional alleles, allowing Cre recombinase-mediated disruption of gene function in a time- and tissue-specific manner. Furthermore, the EUCOMM program will generate up to 320 mouse lines from the EUCOMM resource and up to 20 new Cre driver mouse lines. The EUCOMM resource of vectors, mutant ES cell lines and mutant mice will be openly available to the scientific community. EUCOMM will be one of the cornerstones of an international effort to create a global mouse mutant resource.

    Briefings in functional genomics & proteomics 2007;6;3;180-5

  • Transcription profile in mouse four-cell, morula, and blastocyst: Genes implicated in compaction and blastocoel formation.

    Cui XS, Li XY, Shen XH, Bae YJ, Kang JJ and Kim NH

    Department of Animal Science, Chungbuk National University, Cheongju, Chungbuk, South Korea.

    To gain insight into early embryo development, we utilized microarray technology to compare gene expression profiles in four-cell (4C), morula (MO), and blastocyst (BL) stage embryos. Differences in spot intensities were normalized, and grouped by using Avadis Prophetic software platform (version 3.3, Strand Genomics Ltd.) and categories were based on the PANTHER and gene ontology (GO) classification system. This technique identified 622 of 7,927 genes as being more highly expressed in MO when compared to 4C (P < 0.05); similarly, we identified 654 of 9,299 genes as being more highly expressed in BL than in MO (P < 0.05). Upregulation of genes for cytoskeletal, cell adhesion, and cell junction proteins were identified in the MO as compared to the 4C stage embryos, this means they could be involved in the cell compaction necessary for the development to the MO. Genes thought to be involved in ion channels, membrane traffic, transfer/carrier proteins, and lipid metabolism were also identified as being expressed at a higher level in the BL stage embryos than in the MO. Real-time RT-PCR was performed to confirm differential expression of selected genes. The identification of the genes being expressed in here will provide insight into the complex gene regulatory networks effecting compaction and blastocoel formation.

    Molecular reproduction and development 2007;74;2;133-43

  • Alpha-actinin-4 is required for normal podocyte adhesion.

    Dandapani SV, Sugimoto H, Matthews BD, Kolb RJ, Sinha S, Gerszten RE, Zhou J, Ingber DE, Kalluri R and Pollak MR

    Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.

    Mutations in the alpha-actinin-4 gene ACTN4 cause an autosomal dominant human kidney disease. Mice deficient in alpha-actinin-4 develop a recessive phenotype characterized by kidney failure, proteinuria, glomerulosclerosis, and retraction of glomerular podocyte foot processes. However, the mechanism by which alpha-actinin-4 deficiency leads to glomerular disease has not been defined. Here, we examined the effect of alpha-actinin-4 deficiency on the adhesive properties of podocytes in vivo and in a cell culture system. In alpha-actinin-4-deficient mice, we observed a decrease in the number of podocytes per glomerulus compared with wild-type mice as well as the presence of podocyte markers in the urine. Podocyte cell lines generated from alpha-actinin-4-deficient mice were less adherent than wild-type cells to glomerular basement membrane (GBM) components collagen IV and laminin 10 and 11. We also observed markedly reduced adhesion of alpha-actinin-4-deficient podocytes under increasing shear stresses. This adhesion deficit was restored by transfecting cells with alpha-actinin-4-GFP. We tested the strength of the integrin receptor-mediated linkages to the cytoskeleton by applying force to microbeads bound to integrin using magnetic pulling cytometry. Beads bound to alpha-actinin-4-deficient podocytes showed greater displacement in response to an applied force than those bound to wild-type cells. Consistent with integrin-dependent alpha-actinin-4-mediated adhesion, phosphorylation of beta1-integrins on alpha-actinin-4-deficient podocytes is reduced. We rescued the phosphorylation deficit by transfecting alpha-actinin-4 into alpha-actinin-4-deficient podocytes. These results suggest that alpha-actinin-4 interacts with integrins and strengthens the podocyte-GBM interaction thereby stabilizing glomerular architecture and preventing disease.

    Funded by: NHLBI NIH HHS: HL65584; NIDDK NIH HHS: DK066017, DK55001, R01 DK059588, R01 DK059588-08

    The Journal of biological chemistry 2007;282;1;467-77

  • FSGS-associated alpha-actinin-4 (K256E) impairs cytoskeletal dynamics in podocytes.

    Michaud JL, Chaisson KM, Parks RJ and Kennedy CR

    Kidney Research Centre and Molecular Medicine Program, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada.

    Mutations in the ACTN4 gene, encoding the actin crosslinking protein alpha-actinin-4, are associated with a familial form of focal segmental glomerulosclerosis (FSGS). Mice with podocyte-specific expression of K256E alpha-actinin-4 develop foot process effacement and glomerulosclerosis, highlighting the importance of the cytoskeleton in podocyte structure and function. K256E alpha-actinin-4 exhibits increased affinity for F-actin. However, the downstream effects of this aberrant binding on podocyte dynamics remain unclear. Wild-type and K256E alpha-actinin-4 were expressed in cultured podocytes via adenoviral infection to determine the effect of the mutation on alpha-actinin-4 subcellular localization and on cytoskeletal-dependent processes such as adhesion, spreading, migration, and formation of foot process-like peripheral projections. Wild-type alpha-actinin-4 was detected primarily in the Triton-soluble fraction of podocyte lysates and localized to membrane-associated cortical actin and focal adhesions, with some expression along stress fibers. Conversely, K256E alpha-actinin-4 was detected predominantly in the Triton-insoluble fraction, was excluded from cortical actin, and localized almost exclusively along stress fibers. Both wild-type and K256E alpha-actinin-4-expressing podocytes adhered equally to an extracellular matrix (collagen-I). However, podocytes expressing K256E alpha-actinin-4 showed a reduced ability to spread and migrate on collagen-I. Lastly, K256E alpha-actinin-4 expression reduced the mean number of actin-rich peripheral projections. Our data suggest that aberrant sequestering of K256E alpha-actinin-4 impairs podocyte spreading, motility, and reduces the number of peripheral projections. Such intrinsic cytoskeletal derangements may underlie initial podocyte damage and foot process effacement encountered in ACTN4-associated FSGS.

    Kidney international 2006;70;6;1054-61

  • Interaction of zonula occludens-1 (ZO-1) with alpha-actinin-4: application of functional proteomics for identification of PDZ domain-associated proteins.

    Chen VC, Li X, Perreault H and Nagy JI

    Department of Chemistry, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.

    The use of recombinant "bait" proteins to capture protein-binding partners, followed by identification of protein interaction networks by mass spectrometry (MS), has gained popularity and widespread acceptance. We have developed an approach using recombinant PDZ protein interaction modules of the membrane-associated guanylate kinase (MAGUK) protein zonula occludens-1 (ZO-1) to pull-down and screen for proteins that interact with these modules via their PDZ domain binding motifs. Identification of proteins by MS of pull-down material was achieved using a vacuum-based chromatography sample preparation device designed for matrix-assisted laser desorption/ionization (MALDI) MS. MS analysis of tryptic fragments in pull-down material revealed a number of potential ZO-1 interacting candidates, including the presence of peptides corresponding to the cortical membrane scaffolding protein alpha-actinin-4. Interaction of alpha-actinin-4 with ZO-1 was confirmed by coimmunoprecipitation of these two proteins from cultured cells, as well as from brain, liver, and heart, and by immunoblot detection of alpha-actinin-4 after pull-down with the first PDZ domain of ZO-1. In contrast, the highly homologous alpha-actinin family member, alpha-actinin-1, displayed no association with ZO-1. Immunofluorescence showed colocalization of alpha-actinin-4 with ZO-1 in cultured HeLa and C6 glioma cells, as well as in a variety of tissues in vivo, including brain, heart, liver, and lung. This study demonstrates the utility of MS-based functional proteomics for identifying cellular components of the ZO-1 scaffolding network. Our finding of the interaction of ZO-1 with alpha-actinin-4 provides a mechanism for linking the known protein recruitment and signaling activities of ZO-1 with alpha-actinin-4-associated plasma membrane proteins that have regulatory activities at cell-cell and cell-extracellular matrix contacts.

    Journal of proteome research 2006;5;9;2123-34

  • Differential binding of cross-reactive anti-DNA antibodies to mesangial cells: the role of alpha-actinin.

    Zhao Z, Deocharan B, Scherer PE, Ozelius LJ and Putterman C

    The Irving and Ruth Claremon Research Laboratory, Division of Rheumatology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

    Target Ag display is a necessary requirement for the expression of certain immune-mediated kidney diseases. We previously had shown that anti-DNA Abs that cross-react with alpha-actinin may be important in the pathogenesis of murine and human lupus nephritis; in murine models, we had found that a significant proportion of pathogenic serum and kidney-deposited Igs are alpha-actinin reactive. Furthermore, a pathogenic anti-DNA/alpha-actinin Ab showed enhanced binding to immortalized mesangial cells (MCs) derived from a lupus prone MRL-lpr/lpr mouse as compared with MCs from BALB/c mice which are not susceptible to spontaneous lupus, suggesting that kidney alpha-actinin expression may be contributing to nephritis. In the current study, we established that two isoforms of alpha-actinin that are present in the kidney, alpha-actinin 1 and alpha-actinin 4, can both be targeted by anti-alpha-actinin Abs. We found novel sequence polymorphisms between MRL-lpr/lpr and BALB/c in the gene for alpha-actinin 4. Moreover, alpha-actinin 4 and a splice variant of alpha-actinin 1 were both expressed at significantly higher levels (mRNA and protein) in MCs from the lupus prone MRL-lpr/lpr strain. Significantly, we were able to confirm these differences in intact kidney by examining glomerular Ig deposition of anti-alpha-actinin Abs. We conclude that enhanced alpha-actinin expression may determine the extent of Ig deposition in the Ab-mediated kidney disease in lupus. Modulation of Ag expression may be a promising approach to down-regulate immune complex formation in the target organ in individuals with circulating pathogenic Abs.

    Funded by: NIAID NIH HHS: P01-AI-51392; NIAMS NIH HHS: R01-AR-48692

    Journal of immunology (Baltimore, Md. : 1950) 2006;176;12;7704-14

  • Identification of multipotent progenitors in the embryonic mouse kidney by a novel colony-forming assay.

    Osafune K, Takasato M, Kispert A, Asashima M and Nishinakamura R

    Division of Stem Cell Regulation, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan.

    Renal stem or progenitor cells with a multilineage differentiation potential remain to be isolated, and the differentiation mechanism of these cell types in kidney development or regeneration processes is unknown. In an attempt to resolve this issue, we set up an in vitro culture system using NIH3T3 cells stably expressing Wnt4 (3T3Wnt4) as a feeder layer, in which a single renal progenitor in the metanephric mesenchyme forms colonies consisting of several types of epithelial cells that exist in glomeruli and renal tubules. We found that only cells strongly expressing Sall1 (Sall1-GFP(high) cells), a zinc-finger nuclear factor essential for kidney development, form colonies, and that they reconstitute a three-dimensional kidney structure in an organ culture setting. We also found that Rac- and JNK-dependent planar cell polarity (PCP) pathways downstream of Wnt4 positively regulate the colony size, and that the JNK pathway is also involved in mesenchymal-to-epithelial transformation of colony-forming progenitors. Thus our colony-forming assay, which identifies multipotent progenitors in the embryonic mouse kidney, can be used for examining mechanisms of renal progenitor differentiation.

    Development (Cambridge, England) 2006;133;1;151-61

  • Proteomic identification of the TRAF6 regulation of vacuolar ATPase for osteoclast function.

    Ryu J, Kim H, Lee SK, Chang EJ, Kim HJ and Kim HH

    Department of Cell and Developmental Biology, Dental Research Institute, College of Dentistry, Seoul National University, Seoul, Korea.

    Osteoclasts are cells specialized for bone resorption. For osteoclast activation, tumor necrosis factor receptor-associated factor 6 (TRAF6) plays a pivotal role. To find new molecules that bind TRAF6 and have a function in osteoclast activation, we employed a proteomic approach. TRAF6-binding proteins were purified from osteoclast cell lysates by affinity chromatography and their identity was disclosed by MS. The identified proteins included several heat shock proteins, actin and actin-binding proteins, and vacuolar ATPase (V-ATPase). V-ATPase, documented for a great increase in expression during osteoclast differentiation, is an important enzyme for osteoclast function; it transports proton to resorption lacunae for hydroxyapatite dissolution. The binding of V-ATPase with TRAF6 was confirmed both in vitro by GST pull-down assays and in osteoclasts by co-immunoprecipitation and confocal microscopy experiments. In addition, the V-ATPase activity associated with TRAF6 increased in osteoclasts stimulated with receptor activator of nuclear factor kappaB ligand (RANKL). Furthermore, a dominant-negative form of TRAF6 abrogated the RANKL stimulation of V-ATPase activity. Our study identified V-ATPase as a TRAF6-binding protein using a proteomics strategy and proved a direct link between these two important molecules for osteoclast function.

    Proteomics 2005;5;16;4152-60

  • Synaptopodin regulates the actin-bundling activity of alpha-actinin in an isoform-specific manner.

    Asanuma K, Kim K, Oh J, Giardino L, Chabanis S, Faul C, Reiser J and Mundel P

    Department of Medicine, Albert Einstein College of Medicine, New York, New York, USA.

    Synaptopodin is the founding member of a novel class of proline-rich actin-associated proteins highly expressed in telencephalic dendrites and renal podocytes. Synaptopodin-deficient (synpo(-/-)) mice lack the dendritic spine apparatus and display impaired activity-dependent long-term synaptic plasticity. In contrast, the ultrastructure of podocytes in synpo(-/-) mice is normal. Here we show that synpo(-/-) mice display impaired recovery from protamine sulfate-induced podocyte foot process (FP) effacement and LPS-induced nephrotic syndrome. Similarly, synpo(-/-) podocytes show impaired actin filament reformation in vitro. We further demonstrate that synaptopodin exists in 3 isoforms, neuronal Synpo-short (685 AA), renal Synpo-long (903 AA), and Synpo-T (181 AA). The C terminus of Synpo-long is identical to that of Synpo-T. All 3 isoforms specifically interact with alpha-actinin and elongate alpha-actinin-induced actin filaments. synpo(-/-) mice lack Synpo-short and Synpo-long expression but show an upregulation of Synpo-T protein expression in podocytes, though not in the brain. Gene silencing of Synpo-T abrogates stress-fiber formation in synpo(-/-) podocytes, demonstrating that Synpo-T serves as a backup for Synpo-long in synpo(-/-) podocytes. In concert, synaptopodin regulates the actin-bundling activity of alpha-actinin in highly dynamic cell compartments, such as podocyte FPs and the dendritic spine apparatus.

    Funded by: NIDA NIH HHS: DA18886, R01 DA018886; NIDDK NIH HHS: DK062472, DK064236, DK57683, P50 DK064236, R01 DK057683, R01 DK062472

    The Journal of clinical investigation 2005;115;5;1188-98

  • Actinin-4 increases cell motility and promotes lymph node metastasis of colorectal cancer.

    Honda K, Yamada T, Hayashida Y, Idogawa M, Sato S, Hasegawa F, Ino Y, Ono M and Hirohashi S

    Chemotherapy Division and Cancer Proteomics Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuoh-ku, Tokyo 104-0045, Japan.

    Enhanced motility of cancer cells by remodeling of the actin cytoskeleton seems crucial in the process of cancer invasion and metastasis. We previously identified an actin-binding protein, actinin-4, as a new biomarker of cancer invasion and an indicator of prognosis for patients with breast cancer. However, its involvement in the mechanisms of cancer invasion and metastasis remains undetermined. The current study tested the role of actinin-4 in the motility and metastatic potential of colorectal cancer cells.

    Quantitative immunofluorescence histochemistry showed that the expression level of the actinin-4 protein was increased in 73.1% (19/26) of the cases of colorectal cancer over the corresponding normal intestinal epithelium. The increased expression of actinin-4 was most significant in dedifferentiated cancer cells at the invasive front. A colorectal cancer cell clone capable of inducing actinin-4 using the tetracycline-regulatory system (designated DLD1 Tet-off ACTN-4) was established. Upon the induction of actinin-4, DLD1 Tet-off ACTN-4 cells spread filopodia and significantly increased their motility ( P = .00027); actinin-4 protein was concentrated at the leading edges of these actin-rich podia. When injected into the mesocecum of severe combined immunodeficient mice, DLD1 Tet-off ACTN4 cells, but not the control cells, metastasized into regional mesenteric lymph nodes, resembling the behavior of clinical cancers. The expression of actinin-4 in focally dedifferentiated cancer cells at the invasive front was significantly correlated with the frequency of lymph node metastasis of colorectal cancer ( P = .038).

    Conclusions: Actinin-4 actively increases cell motility and promotes lymph node metastasis of colorectal cancer.

    Gastroenterology 2005;128;1;51-62

  • 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

  • Phosphorylation of mouse LASP-1 on threonine 156 by cAMP- and cGMP-dependent protein kinase.

    Keicher C, Gambaryan S, Schulze E, Marcus K, Meyer HE and Butt E

    Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Josef-Schneider-Str. 2, D-97080 Würzburg, Germany.

    LIM and SH3 domain protein (LASP-1) is a specific focal adhesion protein involved in cell migration. Overlay studies demonstrate that LASP-1 directly binds to the proline-rich domains of zyxin, lipoma preferred partner (LPP), and vasodilator-stimulated phosphoprotein (VASP), with zyxin being the most prominent interacting partner. Despite the LIM/zinc-finger domain, hypothesized to be involved in homodimerization, LASP-1 exists as a monomer. In vitro phosphorylation of recombinant mouse LASP-1 by cAMP- and cGMP-dependent protein kinase (PKA and PKG, respectively) occurs at serine 61, serine 99, and threonine 156 whereas in intact cells mouse LASP-1 is phosphorylated only at threonine 156. This site is different from the known in vivo phosphorylation sites in human (serine 146) and rabbit (serine 99 and serine 146). Nevertheless, immunofluorescence of LASP-1 in human and mouse mesangial cells revealed no difference in subcellular distribution. Exposure of the cells to forskolin induced a translocation of both, human and mouse LASP-1, from the focal contacts to the cell interior without affecting F-actin structure. Immunoblotting of LASP-1 in various mouse and human tissues detected a similar prominent expression in non-muscle tissue. Altogether, our data suggest so far no functional differences between human and mouse LASP-1.

    Biochemical and biophysical research communications 2004;324;1;308-16

  • The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

    Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Morrin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J and MGC Project Team

    The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

    Funded by: PHS HHS: N01-C0-12400

    Genome research 2004;14;10B;2121-7

  • Alpha-actinin-4-mediated FSGS: an inherited kidney disease caused by an aggregated and rapidly degraded cytoskeletal protein.

    Yao J, Le TC, Kos CH, Henderson JM, Allen PG, Denker BM and Pollak MR

    Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.

    Focal segmental glomerulosclerosis (FSGS) is a common pattern of renal injury, seen as both a primary disorder and as a consequence of underlying insults such as diabetes, HIV infection, and hypertension. Point mutations in the alpha-actinin-4 gene ACTN4 cause an autosomal dominant form of human FSGS. We characterized the biological effect of these mutations by biochemical assays, cell-based studies, and the development of a new mouse model. We found that a fraction of the mutant protein forms large aggregates with a high sedimentation coefficient. Localization of mutant alpha-actinin-4 in transfected and injected cells, as well as in situ glomeruli, showed aggregates of the mutant protein. Video microscopy showed the mutant alpha-actinin-4 to be markedly less dynamic than the wild-type protein. We developed a "knockin" mouse model by replacing Actn4 with a copy of the gene bearing an FSGS-associated point mutation. We used cells from these mice to show increased degradation of mutant alpha-actinin-4, mediated, at least in part, by the ubiquitin-proteasome pathway. We correlate these findings with studies of alpha-actinin-4 expression in human samples. "Knockin" mice with a disease-associated Actn4 mutation develop a phenotype similar to that observed in humans. Comparison of the phenotype in wild-type, heterozygous, and homozygous Actn4 "knockin" and "knockout" mice, together with our in vitro data, suggests that the phenotypes in mice and humans involve both gain-of-function and loss-of-function mechanisms.

    Funded by: NIDDK NIH HHS: DK59588, R01 DK059588, R37 DK059588; NIGMS NIH HHS: GM057256, GM55223, R01 GM055223, R01 GM057256, R29 GM055223

    PLoS biology 2004;2;6;e167

  • Mutant alpha-actinin-4 promotes tumorigenicity and regulates cell motility of a human lung carcinoma.

    Menez J, Le Maux Chansac B, Dorothée G, Vergnon I, Jalil A, Carlier MF, Chouaib S and Mami-Chouaib F

    Laboratoire Cytokines et Immunologie des tumeurs Humaines, U487 INSERM, Institut Fédératif de Recherche 54, Institut Gustave Roussy, F-94805 Villejuif Cedex, France.

    The precise role of alpha-actinin-4 encoding gene (ACTN4) is not very well understood. It has been reported to elicit tumor suppressor activity and to regulate cellular motility. To further assess the function of human ACTN4, we studied a lung carcinoma cell line expressing a mutated alpha-actinin-4, which is recognized as a tumor antigen by autologous CD8(+) cytotoxic T lymphocytes (CTL). Confocal immunofluorescence microscopy indicated that, while wild-type (WT) alpha-actinin-4 stains into actin cytoskeleton and cell surface ruffles, the mutated protein is only dispersed in the cytoplasm of the lung carcinoma cells. This loss of association with the cell surface did not appear to correlate with a decrease in in vitro alpha-actinin-4 crosslinking to filamentous (F)-actin. Interestingly, experiments using cell lines stably expressing ACTN4 demonstrated that as opposed to WT gene, mutant ACTN4 was unable to inhibit tumor cell growth in vitro and in vivo. Moreover, the expression of mutant alpha-actinin-4 resulted in the loss of tumor cell capacity to migrate. The identification of an inactivating mutation in ACTN4 emphasizes its role as a tumor suppressor gene and underlines the involvement of cytoskeleton alteration in tumor development and metastasis.

    Oncogene 2004;23;15;2630-9

  • 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

  • Hypoxia inactivates inducible nitric oxide synthase in mouse macrophages by disrupting its interaction with alpha-actinin 4.

    Daniliuc S, Bitterman H, Rahat MA, Kinarty A, Rosenzweig D, Lahat N and Nitza L

    Immunology Research Unit and Ischemia-Shock Research Laboratory, Carmel Medical Center, Rappaport Family Institute for Research in the Medical Sciences, and Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel.

    Nitric oxide, produced in macrophages by the high output isoform inducible NO synthase (iNOS), is associated with cytotoxic effects and modulation of Th1 inflammatory/immune responses. Ischemia and reperfusion lead to generation of high NO levels that contribute to irreversible tissue damage. Ischemia and reperfusion, as well as their in vitro simulation by hypoxia and reoxygenation, induce the expression of iNOS in macrophages. However, the molecular regulation of iNOS expression and activity in hypoxia and reoxygenation has hardly been studied. We show in this study that IFN-gamma induced iNOS protein expression (by 50-fold from control, p < 0.01) and nitrite accumulation (71.6 +/- 14 micro M, p < 0.01 relative to control), and that hypoxia inhibited NO production (7.6 +/- 1.7 micro M, p < 0.01) without altering iNOS protein expression. Only prolonged reoxygenation restored NO production, thus ruling out the possibility that lack of oxygen, as a substrate, was the cause of hypoxia-induced iNOS inactivation. Hypoxia did not change the ratio between iNOS monomers and dimers, which are essential for iNOS activity, but the dimers were unable to produce NO, despite the exogenous addition of all cofactors and oxygen. Using immunoprecipitation, mass spectroscopy, and confocal microscopy, we demonstrated in normoxia, but not in hypoxia, an interaction between iNOS and alpha-actinin 4, an adapter protein that anchors enzymes to the actin cytoskeleton. Furthermore, hypoxia caused displacement of iNOS from the submembranal zones. We suggest that the intracellular localization and interactions of iNOS with the cytoskeleton are crucial for its activity, and that hypoxia inactivates iNOS by disrupting these interactions.

    Journal of immunology (Baltimore, Md. : 1950) 2003;171;6;3225-32

  • A large-scale, gene-driven mutagenesis approach for the functional analysis of the mouse genome.

    Hansen J, Floss T, Van Sloun P, Füchtbauer EM, Vauti F, Arnold HH, Schnütgen F, Wurst W, von Melchner H and Ruiz P

    Institute of Developmental Genetics, GSF-National Research Center for Environment and Health, D-85764 Neuherberg, Germany.

    A major challenge of the postgenomic era is the functional characterization of every single gene within the mammalian genome. In an effort to address this challenge, we assembled a collection of mutations in mouse embryonic stem (ES) cells, which is the largest publicly accessible collection of such mutations to date. Using four different gene-trap vectors, we generated 5,142 sequences adjacent to the gene-trap integration sites (gene-trap sequence tags; http://genetrap.de) from >11,000 ES cell clones. Although most of the gene-trap vector insertions occurred randomly throughout the genome, we found both vector-independent and vector-specific integration "hot spots." Because >50% of the hot spots were vector-specific, we conclude that the most effective way to saturate the mouse genome with gene-trap insertions is by using a combination of gene-trap vectors. When a random sample of gene-trap integrations was passaged to the germ line, 59% (17 of 29) produced an observable phenotype in transgenic mice, a frequency similar to that achieved by conventional gene targeting. Thus, gene trapping allows a large-scale and cost-effective production of ES cell clones with mutations distributed throughout the genome, a resource likely to accelerate genome annotation and the in vivo modeling of human disease.

    Proceedings of the National Academy of Sciences of the United States of America 2003;100;17;9918-22

  • Mice deficient in alpha-actinin-4 have severe glomerular disease.

    Kos CH, Le TC, Sinha S, Henderson JM, Kim SH, Sugimoto H, Kalluri R, Gerszten RE and Pollak MR

    Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.

    Dominantly inherited mutations in ACTN4, which encodes alpha-actinin-4, cause a form of human focal and segmental glomerulosclerosis (FSGS). By homologous recombination in ES cells, we developed a mouse model deficient in Actn4. Mice homozygous for the targeted allele have no detectable alpha-actinin-4 protein expression. The number of homozygous mice observed was lower than expected under mendelian inheritance. Surviving mice homozygous for the targeted allele show progressive proteinuria, glomerular disease, and typically death by several months of age. Light microscopic analysis shows extensive glomerular disease and proteinaceous casts. Electron microscopic examination shows focal areas of podocyte foot-process effacement in young mice, and diffuse effacement and globally disrupted podocyte morphology in older mice. Despite the widespread distribution of alpha-actinin-4, histologic examination of mice showed abnormalities only in the kidneys. In contrast to the dominantly inherited human form of ACTN4-associated FSGS, here we show that the absence of alpha-actinin-4 causes a recessive form of disease in mice. Cell motility, as measured by lymphocyte chemotaxis assays, was increased in the absence of alpha-actinin-4. We conclude that alpha-actinin-4 is required for normal glomerular function. We further conclude that the nonsarcomeric forms of alpha-actinin (alpha-actinin-1 and alpha-actinin-4) are not functionally redundant. In addition, these genetic studies demonstrate that the nonsarcomeric alpha-actinin-4 is involved in the regulation of cell movement.

    Funded by: NHLBI NIH HHS: HL-07208, HL-65584, R01 HL065584, T32 HL007208; NIDDK NIH HHS: DK-51711, DK-55001, DK-59588, R01 DK055001, R01 DK059588, R37 DK059588

    The Journal of clinical investigation 2003;111;11;1683-90

  • Focal and segmental glomerulosclerosis in mice with podocyte-specific expression of mutant alpha-actinin-4.

    Michaud JL, Lemieux LI, Dubé M, Vanderhyden BC, Robertson SJ and Kennedy CR

    Kidney Research Centre, Division of Nephrology, Department of Medicine, The Ottawa Hospital, Ottawa Health Research Institute, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5.

    Mutations in the gene encoding alpha-actinin-4 (ACTN4), an actin crosslinking protein, are associated with a form of autosomal dominant focal segmental glomerulosclerosis (FSGS). To better study its progression, a transgenic mouse model was developed by expressing murine alpha-actinin-4 containing a mutation analogous to that affecting a human FSGS family in a podocyte-specific manner using the murine nephrin promoter. Consistent with human ACTN4-associated FSGS, which shows incomplete penetrance, a proportion of the transgenic mice exhibited significant albuminuria (8 of 18), while the overall average systolic BP was elevated in both proteinuric and non-proteinuric ACTN4-mutant mice. Immunofluorescence confirmed podocyte-specific expression of mutant alpha-actinin-4, and real-time RT-PCR revealed that HA-ACTN4 mRNA levels were higher in proteinuric versus non-proteinuric ACTN4-mutant mice. Only proteinuric mice exhibited histologic features consistent with human ACTN4-associated FSGS, including segmental sclerosis and tuft adhesion of some glomeruli, tubular dilatation, mesangial matrix expansion, as well as regions of podocyte vacuolization and foot process fusion. Consistent with such podocyte damage, proteinuric ACTN4-mutant kidneys exhibited significantly reduced mRNA and protein levels of the slit diaphragm component, nephrin. This newly developed mouse model of human ACTN4-associated FSGS suggests a cause-and-effect relationship between actin cytoskeleton dysregulation by mutant alpha-actinin-4 and the deterioration of the nephrin-supported slit diaphragm complex.

    Journal of the American Society of Nephrology : JASN 2003;14;5;1200-11

  • BayGenomics: a resource of insertional mutations in mouse embryonic stem cells.

    Stryke D, Kawamoto M, Huang CC, Johns SJ, King LA, Harper CA, Meng EC, Lee RE, Yee A, L'Italien L, Chuang PT, Young SG, Skarnes WC, Babbitt PC and Ferrin TE

    Department of Pharmaceutical Chemistry, University of California San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA.

    The BayGenomics gene-trap resource (http://baygenomics.ucsf.edu) provides researchers with access to thousands of mouse embryonic stem (ES) cell lines harboring characterized insertional mutations in both known and novel genes. Each cell line contains an insertional mutation in a specific gene. The identity of the gene that has been interrupted can be determined from a DNA sequence tag. Approximately 75% of our cell lines contain insertional mutations in known mouse genes or genes that share strong sequence similarities with genes that have been identified in other organisms. These cell lines readily transmit the mutation to the germline of mice and many mutant lines of mice have already been generated from this resource. BayGenomics provides facile access to our entire database, including sequence tags for each mutant ES cell line, through the World Wide Web. Investigators can browse our resource, search for specific entries, download any portion of our database and BLAST sequences of interest against our entire set of cell line sequence tags. They can then obtain the mutant ES cell line for the purpose of generating knockout mice.

    Funded by: NCRR NIH HHS: P41 RR001081, P41 RR01081; NHLBI NIH HHS: U01 HL066621, U01 HL66621

    Nucleic acids research 2003;31;1;278-81

  • The mouse Kreisler (Krml1/MafB) segmentation gene is required for differentiation of glomerular visceral epithelial cells.

    Sadl V, Jin F, Yu J, Cui S, Holmyard D, Quaggin S, Barsh G and Cordes S

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

    Molecular components of the glomerular filtration mechanism play critical roles in renal diseases. Many of these components are produced during the final stages of differentiation of glomerular visceral epithelial cells, also known as podocytes. While basic domain leucine zipper (bZip) transcription factors of the Maf subfamily have been implicated in cellular differentiation processes, Kreisler (Krml1/MafB), the gene affected in the mouse kreisler (kr) mutation, is known for its role in hindbrain patterning. Here we show that mice homozygous for the kr(enu) mutation develop renal disease and that Kreisler is essential for cellular differentiation of podocytes. Consistent with abnormal podocyte differentiation, kr(enu) homozygotes show proteinuria, and fusion and effacement of podocyte foot processes, which are also observed in the nephrotic syndrome. Kreisler acts during the final stages of glomerular development-the transition between the capillary loop and mature stages-and downstream of the Pod1 basic domain helix-loop-helix transcription factor. The levels of Podocin, the gene mutated in autosomal recessive steroid-resistant nephrotic syndrome (NPHS2), and Nephrin, the gene mutated in congenital nephrotic syndrome of the Finnish type (NPHS1), are slightly reduced in kr(enu)/kr(enu) podocytes. However, these observations alone are unlikely to account for the aberrant podocyte foot process formation. Thus, Kreisler must regulate other unknown genes required for podocyte function and with possible roles in kidney disease.

    Developmental biology 2002;249;1;16-29

  • Raver1, a dual compartment protein, is a ligand for PTB/hnRNPI and microfilament attachment proteins.

    Hüttelmaier S, Illenberger S, Grosheva I, Rüdiger M, Singer RH and Jockusch BM

    Cell Biology, Zoological Institute, Technical University of Braunschweig, D-38092 Braunschweig, Germany.

    By screening a yeast two-hybrid library with COOH-terminal fragments of vinculin/metavinculin as the bait, we identified a new protein termed raver1. Raver1 is an 80-kD multidomain protein and widely expressed but to varying amounts in different cell lines. In situ and in vitro, raver1 forms complexes with the microfilament-associated proteins vinculin, metavinculin, and alpha-actinin and colocalizes with vinculin/metavinculin and alpha-actinin at microfilament attachment sites, such as cell-cell and cell matrix contacts of epithelial cells and fibroblasts, respectively, and in costameres of skeletal muscle. The NH2-terminal part of raver1 contains three RNA recognition motifs with homology to members of the heterogeneous nuclear RNP (hnRNP) family. Raver1 colocalizes with polypyrimidine tract binding protein (PTB)/hnRNPI, a protein involved in RNA splicing of microfilament proteins, in the perinucleolar compartment and forms complexes with PTB/hnRNPI. Hence, raver1 is a dual compartment protein, which is consistent with the presence of nuclear location signal and nuclear export sequence motifs in its sequence. During muscle differentiation, raver1 migrates from the nucleus to the costamere. We propose that raver1 may coordinate RNA processing and targeting as required for microfilament anchoring in specific adhesion sites.

    The Journal of cell biology 2001;155;5;775-86

  • Construction of long-transcript enriched cDNA libraries from submicrogram amounts of total RNAs by a universal PCR amplification method.

    Piao Y, Ko NT, Lim MK and Ko MS

    Developmental Genomics and Aging Section, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA.

    Here we report a novel design of linker primer that allows one to differentially amplify long tracts (average 3.0 kb with size ranges of 1-7 kb) or short DNAs (average 1.5 kb with size ranges of 0.5-3 kb) from a complex mixture. The method allows one to generate cDNA libraries enriched for long transcripts without size selection of insert DNAs. One representative library from newborn kidney includes 70% of clones bearing ATG start codons. A comparable library has been generated from 20 mouse blastocysts, containing only approximately 40 ng of total RNA. This universal PCR amplification scheme can provide a route to isolate very large cDNAs, even if they are expressed at very low levels.

    Genome research 2001;11;9;1553-8

  • Differential expression of the actin-binding proteins, alpha-actinin-2 and -3, in different species: implications for the evolution of functional redundancy.

    Mills M, Yang N, Weinberger R, Vander Woude DL, Beggs AH, Easteal S and North K

    Neurogenetics Research Unit, Children's Hospital at Westmead, Westmead, Sydney, NSW 2145, Australia.

    The alpha-actinins are a multigene family of four actin-binding proteins related to dystrophin. The two skeletal muscle isoforms of alpha-actinin (ACTN2 and ACTN3) are major structural components of the Z-line involved in anchoring the actin-containing thin filaments. In humans, ACTN2 is expressed in all muscle fibres, while ACTN3 expression is restricted to a subset of type 2 fibres. We have recently demonstrated that alpha-actinin-3 is absent in approximately 18% of individuals in a range of human populations, and that homozygosity for a premature stop codon (577X) accounts for most cases of true alpha-actinin-3 deficiency. Absence of alpha-actinin-3 is not associated with an obvious disease phenotype, raising the possibility that ACTN3 is functionally redundant in humans, and that alpha-actinin-2 is able to compensate for alpha-actinin-3 deficiency. We now present data concerning the expression of ACTN3 in other species. Genotyping of non-human primates indicates that the 577X null mutation has likely arisen in humans. The mouse genome contains four orthologues which all map to evolutionarily conserved syntenic regions for the four human genes. Murine Actn2 and Actn3 are differentially expressed, spatially and temporally, during embryonic development and, in contrast to humans, alpha-actinin-2 expression does not completely overlap alpha-actinin-3 in postnatal skeletal muscle, suggesting independent function. Furthermore, sequence comparison of human, mouse and chicken alpha-actinin genes demonstrates that ACTN3 has been conserved over a long period of evolutionary time, implying a constraint on evolutionary rate imposed by continued function of the gene. These observations provide a real framework in which to test theoretical models of genetic redundancy as they apply to human populations. In addition we highlight the need for caution in making conclusions about gene function from the phenotypic consequences of loss-of-function mutations in animal knockout models.

    Funded by: NIAMS NIH HHS: K02 AR02026, R01 AR44345

    Human molecular genetics 2001;10;13;1335-46

  • Gene structure, chromosomal localization, and expression pattern of Capn12, a new member of the calpain large subunit gene family.

    Dear TN, Meier NT, Hunn M and Boehm T

    Max-Planck Institute for Immunobiology, Stuebeweg 51, Freiburg, D-79108, Germany. dear@immunbio.mpg.de

    We report the identification of mouse Capn12, a new member of the calpain large subunit gene family. It possesses potential protease and calcium-binding domains, features typical of the classical calpains. In situ hybridization and Northern blot analysis demonstrate that during the anagen phase of the hair cycle the cortex of the hair follicle is the major expression site of Capn12. The gene was sequenced in its entirety and consists of 21 exons spanning 13 kb with an exon-intron structure typical of the calpain gene family. The last exon of the mouse Actn4 gene overlaps the 3' end of Capn12 but in the opposite orientation. This overlap between the two genes is conserved in the human genome. Three versions of the Capn12 mRNA transcript were identified. They occur as a result of alternative splicing, and two of these encode a protein lacking the C-terminal calmodulin-like domain. Radiation hybrid mapping localized Capn12 to mouse chromosome 7, closely linked to a marker positioned at 10.4 cM. Refined mapping of Capn5, also previously localized to chromosome 7, indicated that it was not closely linked to Capn12, mapping tightly linked to a marker positioned at 48.5 cM.

    Genomics 2000;68;2;152-60

  • Actinin-4 is preferentially involved in circular ruffling and macropinocytosis in mouse macrophages: analysis by fluorescence ratio imaging.

    Araki N, Hatae T, Yamada T and Hirohashi S

    Department of Anatomy, Kagawa Medical University, Miki, Kagawa 761-0793, Japan. naraki@kms.ac.jp

    We have applied fluorescence ratio imaging to the analysis of an actin-binding protein concentration relative to F-actin in macrophages, in order to explore the role of a novel (alpha)-actinin isoform, actinin-4, relative to that of the classical isoform, actinin-1. Conventional immunofluorescence images showed that both isoforms were enriched in F-actin-rich regions such as cell surface ruffles. However, ratio images further demonstrated that actinin-4 concentrations relative to F-actin were higher in peripheral inward curved ruffles and dorsal circular ruffles, presumed precursor forms of macropinosomes, than in straight linear ruffles, while actinin-1 concentrations were uniform among the different types of ruffles. Macropinosome pulse-labeling and chase experiments indicated that actinin-4 was also closely associated with newly formed macropinosomes and gradually dissociated with their maturation. Consistent with ratio imaging data, macrophages scrape-loaded with anti-actinin-4 showed a more reduced rate of macropinocytosis than those loaded with anti-actinin-1. Altogether, these results indicate that actinin-4 and actinin-1 contribute differently to F-actin dynamics, that actinin-4 is more preferentially involved in early stages of macropinocytosis than actinin-1. A similar redistribution of actinin-4 was also observed during phagocytosis, suggesting that actinin-4 may play the same role in the two mechanistically analogous types of endocytosis, i.e. macropinocytosis and phagocytosis.

    Journal of cell science 2000;113 ( Pt 18);3329-40

  • 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

  • Large-scale cDNA analysis reveals phased gene expression patterns during preimplantation mouse development.

    Ko MS, Kitchen JR, Wang X, Threat TA, Wang X, Hasegawa A, Sun T, Grahovac MJ, Kargul GJ, Lim MK, Cui Y, Sano Y, Tanaka T, Liang Y, Mason S, Paonessa PD, Sauls AD, DePalma GE, Sharara R, Rowe LB, Eppig J, Morrell C and Doi H

    ERATO Doi Bioasymmetry Project, JST, Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48202, USA. kom@grc.nia.nih.gov

    Little is known about gene action in the preimplantation events that initiate mammalian development. Based on cDNA collections made from each stage from egg to blastocyst, 25438 3'-ESTs were derived, and represent 9718 genes, half of them novel. Thus, a considerable fraction of mammalian genes is dedicated to embryonic expression. This study reveals profound changes in gene expression that include the transient induction of transcripts at each stage. These results raise the possibility that development is driven by the action of a series of stage-specific expressed genes. The new genes, 798 of them placed on the mouse genetic map, provide entry points for analyses of human and mouse developmental disorders.

    Funded by: NICHD NIH HHS: R01HD32243

    Development (Cambridge, England) 2000;127;8;1737-49

Gene lists (7)

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
L00000060 G2C Mus musculus BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus (ortho) 748
L00000062 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus 984
L00000070 G2C Mus musculus BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list (ortho) 1461
L00000072 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list 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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