G2Cdb::Gene report

Gene id
G00001513
Gene symbol
GIPC1 (HGNC)
Species
Homo sapiens
Description
GIPC PDZ domain containing family, member 1
Orthologue
G00000264 (Mus musculus)

Databases (8)

Curated Gene
OTTHUMG00000071674 (Vega human gene)
Gene
ENSG00000123159 (Ensembl human gene)
10755 (Entrez Gene)
592 (G2Cdb plasticity & disease)
GIPC1 (GeneCards)
Literature
605072 (OMIM)
Marker Symbol
HGNC:1226 (HGNC)
Protein Sequence
O14908 (UniProt)

Synonyms (7)

  • GIPC
  • GLUT1CBP
  • Hs.6454
  • NIP
  • SEMCAP
  • SYNECTIN
  • TIP-2

Literature (50)

Pubmed - other

  • Interaction of hepatitis B virus core protein with human GIPC1.

    Razanskas R and Sasnauskas K

    Institute of Biotechnology, Graiciuno 8, 02241, Vilnius, Lithuania. raimis@ibt.lt

    Up to now, little is known about hepatitis B virus core protein (HBc) interactions with host-cell proteins, although such interactions might be essential for virus propagation and pathogenicity. In this work, a human liver cDNA library was screened for proteins interacting with HBc. Among several HBc-interacting partners selected, it interacted most strongly with the human protein GIPC1. A common protein interaction domain, PDZ, was identified as the region that is sufficient for the interaction with HBc. The core protein has a putative C-terminal PDZ-interacting motif, and this sequence proved to be important for the interaction with GIPC1.

    Archives of virology 2010;155;2;247-50

  • Overexpression of myosin VI in prostate cancer cells enhances PSA and VEGF secretion, but has no effect on endocytosis.

    Puri C, Chibalina MV, Arden SD, Kruppa AJ, Kendrick-Jones J and Buss F

    Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge, UK.

    Tissue expression microarrays, employed to determine the players and mechanisms leading to prostate cancer development, have consistently shown that myosin VI, a unique actin-based motor, is upregulated in medium-grade human prostate cancers. Thus, to understand the role of myosin VI in prostate cancer development, we have characterized its intracellular localization and function in the prostate cancer cell line LNCaP. Using light and electron microscopy, we identified myosin VI on Rab5-positive early endosomes, as well as on recycling endosomes and the trans-Golgi network. Intracellular targeting seems to involve two myosin VI-interacting proteins, GIPC and LMTK2, both of which can be co-immunoprecipitated with myosin VI from LNCaP cells. The absence of Disabled-2 (Dab2), a tumour suppressor and myosin VI-binding partner, inhibits recruitment of myosin VI to endocytic structures at the plasma membrane in LNCaP cells, but interestingly has no effect on endocytosis. Small interfering RNA-mediated downregulation of myosin VI expression results in a significant reduction in prostate-specific antigen (PSA) and vascular endothelial growth factor (VEGF) secretion in LNCaP cells. Our results suggest that in prostate cancer cells, myosin VI regulates protein secretion, but the overexpression of myosin VI has no major impact on clathrin-mediated endocytosis.

    Funded by: Cancer Research UK: A7548; Medical Research Council: MC_U105184323; Wellcome Trust

    Oncogene 2010;29;2;188-200

  • An essential role for the Glut1 PDZ-binding motif in growth factor regulation of Glut1 degradation and trafficking.

    Wieman HL, Horn SR, Jacobs SR, Altman BJ, Kornbluth S and Rathmell JC

    Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.

    Cell surface localization of the Glut (glucose transporter), Glut1, is a cytokine-controlled process essential to support the metabolism and survival of haemopoietic cells. Molecular mechanisms that regulate Glut1 trafficking, however, are not certain. In the present study, we show that a C-terminal PDZ-binding motif in Glut1 is critical to promote maximal cytokine-stimulated Glut1 cell surface localization and prevent Glut1 lysosomal degradation in the absence of growth factor. Disruption of this PDZ-binding sequence through deletion or point mutation sharply decreased surface Glut1 levels and led to rapid targeting of internalized Glut1 to lysosomes for proteolysis, particularly in growth factor-deprived cells. The PDZ-domain protein, GIPC (G(alpha)-interacting protein-interacting protein, C-terminus), bound to Glut1 in part via the Glut1 C-terminal PDZ-binding motif, and we found that GIPC deficiency decreased Glut1 surface levels and glucose uptake. Unlike the Glut1 degradation observed on mutation of the Glut1 PDZ-binding domain, however, GIPC deficiency resulted in accumulation of intracellular Glut1 in a pool distinct from the recycling pathway of the TfR (transferrin receptor). Blockade of Glut1 lysosomal targeting after growth factor withdrawal also led to intracellular accumulation of Glut1, a portion of which could be rapidly restored to the cell surface after growth factor stimulation. These results indicate that the C-terminal PDZ-binding motif of Glut1 plays a key role in growth factor regulation of glucose uptake by both allowing GIPC to promote Glut1 trafficking to the cell surface and protecting intracellular Glut1 from lysosomal degradation after growth factor withdrawal, thus allowing the potential for a rapid return of intracellular Glut1 to the cell surface on restimulation.

    Funded by: NIAID NIH HHS: R01 AI063345, R01 AI063345-04, R01AI063345

    The Biochemical journal 2009;418;2;345-67

  • Endoglin promotes transforming growth factor beta-mediated Smad 1/5/8 signaling and inhibits endothelial cell migration through its association with GIPC.

    Lee NY, Ray B, How T and Blobe GC

    Department of Medicine, Duke University Medical Center, Durham, North Carolina 27708, USA.

    Transforming growth factor beta (TGF-beta) signals through two distinct pathways to regulate endothelial cell proliferation, migration, and angiogenesis, the ALK-1/Smad 1/5/8 and ALK-5/Smad2/3 pathways. Endoglin is a co-receptor predominantly expressed in endothelial cells that participates in TGFbeta-mediated signaling with ALK-1 and ALK-5 and regulates critical aspects of cellular and biological responses. The embryonic lethal phenotype of knock-out mice because of defects in angiogenesis and disease-causing mutations resulting in human vascular diseases both support essential roles for endoglin, ALK-1, and ALK-5 in the vasculature. However, the mechanism by which endoglin mediates TGF-beta signaling through ALK-1 and ALK-5 has remained elusive. Here we describe a novel interaction between endoglin and GIPC, a scaffolding protein known to regulate cell surface receptor expression and trafficking. Co-immunoprecipitation and immunofluorescence confocal studies both demonstrate a specific interaction between endoglin and GIPC in endothelial cells, mediated by a class I PDZ binding motif in the cytoplasmic domain of endoglin. Subcellular distribution studies demonstrate that endoglin recruits GIPC to the plasma membrane and co-localizes with GIPC in a TGFbeta-independent manner, with GIPC-promoting cell surface retention of endoglin. Endoglin specifically enhanced TGF-beta1-induced phosphorylation of Smad 1/5/8, increased a Smad 1/5/8 responsive promoter, and inhibited endothelial cell migration in a manner dependent on the ability of endoglin to interact with GIPC. These studies define a novel mechanism for the regulation of endoglin signaling and function in endothelial cells and demonstrate a new role for GIPC in TGF-beta signaling.

    Funded by: NCI NIH HHS: R01-CA105255

    The Journal of biological chemistry 2008;283;47;32527-33

  • A human monoclonal autoantibody to breast cancer identifies the PDZ domain containing protein GIPC1 as a novel breast cancer-associated antigen.

    Rudchenko S, Scanlan M, Kalantarov G, Yavelsky V, Levy C, Estabrook A, Old L, Chan GL, Lobel L and Trakht I

    College of Physicians and Surgeons, Columbia University, 630 W, 168 St,, New York, NY 10032, USA. RudchenkoS@HSS.EDU

    Background: We have been studying the native autoimmune response to cancer through the isolation of human monoclonal antibodies that are cancer specific from cancer patients. To facilitate this work we previously developed a fusion partner cell line for human lymphocytes, MFP-2, that fuses efficiently with both human lymph node lymphocytes and peripheral blood lymphocytes. Using this unique trioma fusion partner cell line we isolated a panel of autologous human monoclonal antibodies, from both peripheral blood and lymph node lymphocytes, which are representative of the native repertoire of anti-cancer specific antibodies from breast cancer patients.

    Methods: The current study employs immunocytochemistry, immunohistochemistry, Western blot analysis as well as Northern blots, Scatchard binding studies and finally SEREX analysis for target antigen identification.

    Results: By application of an expression cloning technique known as SEREX, we determined that the target antigen for two monoclonal antibodies, 27.B1 and 27.F7, derived from lymph node B-cells of a breast cancer patient, is the PDZ domain-containing protein known as GIPC1. This protein is highly expressed not only in cultured human breast cancer cells, but also in primary and metastatic tumor tissues and its overexpression appears to be cancer cell specific. Confocal microscopy revealed cell membrane and cytoplasmic localization of the target protein, which is consistent with previous studies of this protein.

    Conclusion: We have determined that GIPC1 is a novel breast cancer-associated immunogenic antigen that is overexpressed in breast cancer. Its role, however, in the initiation and/or progression of breast cancer remains unclear and needs further clarification.

    BMC cancer 2008;8;248

  • Native human autoantibodies targeting GIPC1 identify differential expression in malignant tumors of the breast and ovary.

    Yavelsky V, Rohkin S, Shaco-Levy R, Tzikinovsky A, Amir T, Kohn H, Delgado B, Rabinovich A, Piura B, Chan G, Kalantarov G, Trakht I and Lobel L

    Department of Virology, Faculty of Health Sciences, Ben Gurion University of Negev, Beer Sheva 84105, Israel. yavelsky@bgu.ac.il

    Background: We have been studying the native humoral immune response to cancer and have isolated a library of fully human autoantibodies to a variety of malignancies. We previously described the isolation and characterization of two fully human monoclonal antibodies, 27.F7 and 27.B1, from breast cancer patients that target the protein known as GIPC1, an accessory PDZ-domain binding protein involved in regulation of G-protein signaling. Human monoclonal antibodies, 27.F7 and 27.B1, to GIPC1 demonstrate specific binding to malignant breast cancer tissue with no reactivity with normal breast tissue.

    Methods: The current study employs cELISA, flow cytometry, Western blot analysis as well as immunocytochemistry, and immunohistochemistry. Data is analyzed statistically with the Fisher one-tail and two-tail tests for two independent samples.

    Results: By screening several other cancer cell lines with 27.F7 and 27.B1 we found consistently strong staining of other human cancer cell lines including SKOV-3 (an ovarian cancer cell line). To further clarify the association of GIPC1 with breast and ovarian cancer we carefully studied 27.F7 and 27.B1 using immunocytochemical and immunohistochemical techniques. An immunohistochemical study of normal ovarian tissue, benign, borderline and malignant ovarian serous tumors, and different types of breast cancer revealed high expression of GIPC1 protein in neoplastic cells. Interestingly, antibodies 27.F7 and 27.B1 demonstrate differential staining of borderline ovarian tumors. Examination of different types of breast cancer demonstrates that the level of GIPC1 expression depends on tumor invasiveness and displays a higher expression than in benign tumors.

    Conclusion: The present pilot study demonstrates that the GIPC1 protein is overexpressed in ovarian and breast cancer, which may provide an important diagnostic and prognostic marker and will constitute the basis for further study of the role that this protein plays in malignant diseases. In addition, this study suggests that human monoclonal antibodies 27.F7 and 27.B1 should be further evaluated as potential diagnostic tools.

    BMC cancer 2008;8;247

  • [GIPC: a new target for therapy in pancreatic adenocarcinoma?].

    Muders MH, Baretton GB, Aust DE, Dutta SK, Wang E, Ikeda Y, Spaller MR, Datta K and Mukhopadhyay D

    Department of Biochemistry and Molecular Biology, Mayo Clinic Cancer Center, Mayo Clinic College of Medicine, Rochester, USA.

    GIPC is highly expressed in human pancreatic adenocarcinoma and is a central protein for the stability of IGF-1R in pancreatic adenocarcinoma cell lines (15). The goal of this study was to prove the importance of GIPC in vivo and to evaluate possible therapeutic strategies that target this protein and its PDZ domain. In vivo effects of GIPC knockout were studied after lentiviral transduction of luciferase-expressing MiaPaCa2 pancreatic cancer cells with shRNA against GIPC; growth characteristics were monitored with bioluminiscence. Knockdown of GIPC led to a significant inhibition of pancreatic tumor cell growth in vivo in different mouse models. To test a possible therapeutic approach, the PDZ domain of GIPC was targeted by a short peptide composed of the amino acid sequence PSQSSSEA. This octapeptide was designed based on the C-terminal binding motif of GAIP. Targeting GIPC with this peptide inhibited the association between IGF-1R and GIPC. The subsequent downregulation of IGF-1R decreased proliferation in vitro and in vivo. In conclusion, our findings suggest that targeting GIPC and its PDZ domain-mediated interaction with the tyrosine kinase receptor IGF-1R could be a promising new treatment option for pancreatic cancer.

    Verhandlungen der Deutschen Gesellschaft fur Pathologie 2007;91;286-93

  • 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

  • TRP1 interacting PDZ-domain protein GIPC forms oligomers and is localized to intracellular vesicles in human melanocytes.

    Kedlaya RH, Bhat KM, Mitchell J, Darnell SJ and Setaluri V

    Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA.

    PDZ proteins coordinate assembly of protein complexes that participate in diverse biological processes. GIPC is a multifunctional PDZ protein that interacts with several soluble and membrane proteins. Unlike most PDZ proteins, GIPC contains single PDZ domain and the mechanisms by which GIPC mediates its actions remain unclear. We investigated the possibility that in lieu of multiple PDZ domains, GIPC forms multimers. Here, we demonstrate that GIPC can bind to itself and that the PDZ domain is involved in GIPC-GIPC interaction. Gel filtration, sucrose gradient centrifugation and chemical cross-linking showed that whereas bulk of cytosolic GIPC was present as monomer, oligomers with an estimated molecular mass corresponding to GIPC homotrimer were readily detectable in the membrane fraction. Modeling of GIPC PDZ domain showed feasibility of trimerization. Immunogold electron microscopy showed that GIPC is present in clusters near vesicles. Our data suggest that oligomers of GIPC mediate its functions in melanocytes.

    Funded by: NIAMS NIH HHS: R01 AR048913, R01 AR048913-05, R01AR048913

    Archives of biochemistry and biophysics 2006;454;2;160-9

  • Binding of internalized receptors to the PDZ domain of GIPC/synectin recruits myosin VI to endocytic vesicles.

    Naccache SN, Hasson T and Horowitz A

    Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093, USA.

    Myosin VI (myo6) is the only actin-based molecular motor that translocates along actin filaments toward the minus end. Myo6 participates in two steps of endocytic trafficking; it is recruited to both clathrin-coated pits and to ensuing uncoated endocytic vesicles (UCV). Although there is evidence suggesting that the PDZ adaptor protein GIPC/synectin is involved in the association of myo6 with UCV, the recruitment mechanism is unknown. We show that GIPC/synectin is required for both internalization of cell surface receptors and for coupling of myo6 to UCV. This coupling occurs via a mechanism wherein engagement of the GIPC/synectin PDZ domain by C termini of internalized receptors facilitates in trans myo6 binding to the GIPC/synectin C terminus located outside of the PDZ domain. Analysis of megalin, a prototypical GIPC/synectin-binding receptor, revealed that deletion of its PDZ-binding motif drastically reduced GIPC/synectin and myo6 recruitment to UCV. Furthermore, interaction with GIPC/synectin was required for megalin's function, as megalin was mistargeted in the renal proximal tubules of GIPC/synectin-null mice and these mice exhibited proteinuria, a condition consistent with defective megalin trafficking.

    Funded by: NEI NIH HHS: EY12695, R01 EY012695; NHLBI NIH HHS: HL67960, R01 HL067960

    Proceedings of the National Academy of Sciences of the United States of America 2006;103;34;12735-40

  • Proteomic analysis of beta1-adrenergic receptor interactions with PDZ scaffold proteins.

    He J, Bellini M, Inuzuka H, Xu J, Xiong Y, Yang X, Castleberry AM and Hall RA

    Department of Biochemistry and Molecular Biology, Capital University of Medical Sciences, Beijing 100054, China.

    Many G protein-coupled receptors possess carboxyl-terminal motifs ideal for interaction with PDZ scaffold proteins, which can control receptor trafficking and signaling in a cell-specific manner. To gain a panoramic view of beta1-adrenergic receptor (beta AR) interactions with PDZ scaffolds, the beta1AR carboxyl terminus was screened against a newly developed proteomic array of PDZ domains. These screens confirmed beta1AR associations with several previously identified PDZ partners, such as PSD-95, MAGI-2, GIPC, and CAL. Moreover, two novel beta1AR-interacting proteins, SAP97 and MAGI-3, were also identified. The beta1AR carboxyl terminus was found to bind specifically to the first PDZ domain of MAGI-3, with the last four amino acids (E-S-K-V) of beta1AR being the key determinants of the interaction. Full-length beta1AR robustly associated with full-length MAGI-3 in cells, and this association was abolished by mutation of the beta1AR terminal valine residue to alanine (V477A), as determined by co-immunoprecipitation experiments and immunofluorescence co-localization studies. MAGI-3 co-expression with beta1AR profoundly impaired beta1AR-mediated ERK1/2 activation but had no apparent effect on beta1AR-mediated cyclic AMP generation or agonist-promoted beta1AR internalization. These findings revealed that the interaction of MAGI-3 with beta1AR can selectively regulate specific aspects of receptor signaling. Moreover, the screens of the PDZ domain proteomic array provide a comprehensive view of beta1AR interactions with PDZ scaffolds, thereby shedding light on the molecular mechanisms by which beta1 AR signaling and trafficking can be regulated in a cell-specific manner.

    The Journal of biological chemistry 2006;281;5;2820-7

  • Insulin and IGF-I phosphorylate eNOS in HUVECs by a caveolin-1 dependent mechanism.

    Repetto S, Salani B, Maggi D and Cordera R

    Department of Endocrinology and Metabolism, University of Genova, Genova, Italy.

    Caveolae are plasmamembrane regions which take part in the regulation of intracellular trafficking and signaling of tyrosine kinase receptors. Insulin and IGF-I receptors and their intracellular substrates localize in caveolae. Also eNOS is targeted to caveolae and caveolin-1, the major caveolar protein, acts as a regulator of eNOS activity. Since Insulin and IGF-I phosphorylate and activate eNOS, we investigated the role of caveolin-1 in Insulin and IGF-I stimulated eNOS activity. Here we show that: (1) in human endothelial cells, Insulin and IGF-I stimulate eNOS phosphorylation in a different manner both qualitatively and quantitatively; (2) caveolin-1 down regulation abolishes Insulin and IGF-I stimulated eNOS phosphorylation. These results suggest that caveolae could represent an intracellular site that contributes to differentiate IR and IGF-IR activity, and demonstrate the role of caveolin-1 in the eNOS activation by Insulin and IGF-I.

    Biochemical and biophysical research communications 2005;337;3;849-52

  • [Analysis of polymorphic variants of gene GIPC1 CGG repeats in healthy individuals and in patients with breast cancer and non-small cell lung cancer].

    Mikhaĭlenko DS, Liubchenko LN, Zborovskaia IB, Strel'nikov VV and Zaletaev DV

    The GIPC1 gene product promotes clustering of some transmembrane receptors, including those involved in carcinogenesis, and protects them against ubiquitin-dependent degradation. The 5' untranslated region of GIPC1 contains a polymorphic trinucleotide CGG repeat, which has not been characterized earlier. In the present study, we have carried out comparative analysis of the allele and genotype frequencies of this repeat in 129 samples of breast cancer (BC), 58 samples of non-small cell lung cancer (NSCLC), and 215 samples of healthy donors. The CGG repeat in the 5' untranslated GIPC1 gene region was shown to be highly polymorphic and represented by at least eight alleles. Alleles CGG10-13 were major, occurring at frequencies of 22, 41, 27, and 9%, respectively; the total frequency of the remaining alleles was approximately 1%. Heterozygosity of the CGG repeat was 0.70. Allele CGG12 was shown to be associated with high risk of developing NSCLC (alpha = 0.05).

    Genetika 2005;41;9;1289-93

  • Semaphorin 4B interacts with the post-synaptic density protein PSD-95/SAP90 and is recruited to synapses through a C-terminal PDZ-binding motif.

    Burkhardt C, Müller M, Badde A, Garner CC, Gundelfinger ED and Püschel AW

    Abt. Molekularbiologie, Institut für Allgemeine Zoologie und Genetik, Westfälische Wilhelms-Universität, Schlossplatz 5, D-48149 Münster, Germany.

    The semaphorins are a large family of proteins that act as guidance signals for axons and dendrites. The class 4 semaphorins are integral membrane proteins that are widely expressed throughout the nervous system. Here, we show that a subclass of these semaphorins is characterized by a PDZ-binding motif at their carboxy-terminus. This sequence mediates the interaction with the post-synaptic density protein PSD-95/SAP90. Co-expression of Sema4B with PSD-95 in COS 7 cells results in the clustering of Sema4B. Sema4B co-localizes with PSD-95 at synaptic contacts between cultured hippocampal neurons. This synaptic localization depends on the presence of the PDZ-binding motif.

    FEBS letters 2005;579;17;3821-8

  • Modulated interaction of the ERM protein, moesin, with CD93.

    Zhang M, Bohlson SS, Dy M and Tenner AJ

    Department of Molecular Biology and Biochemistry, Center for Immunology, University of California, Irvine, CA 92697, USA.

    CD93 is a cell-surface glycoprotein that has been shown to influence defence collagen-enhanced Fc-receptor or CR1-mediated phagocytosis of suboptimally opsonized targets in vitro, and CD93-deficient mice are defective in the clearance of apoptotic cells in vivo. To investigate the mechanism of CD93 modulation of phagocytic activity, GST fusion proteins containing the 47 amino acid intracellular domain (GST-Cyto), or various mutants of the intracellular domain of CD93, were constructed and used to identify intracellular CD93-binding molecules. The intracellular protein moesin, well characterized for its role in linking transmembrane proteins to the cytoskeleton and in cytoskeletal remodelling, bound to GST-Cyto when either cell lysates or recombinant moesin were used as a source of interacting molecules. An association of moesin with CD93 within intact cells was confirmed by co-capping moesin with CD93 in human monocytes. The moesin-binding site on CD93 mapped to the first four positively charged amino acids in the juxtamembrane region of the CD93 cytoplasmic tail. Interestingly, deletion of the last 11 amino acids from the C terminus of CD93 (GST-Cyto-C11) dramatically increased moesin binding to the cytoplasmic tail of CD93 in the cell lysate assay, but not when the binding of purified recombinant moesin was assessed. Furthermore, moesin binding to CD93 was enhanced by the addition of phosphatidylinositol 4,5-bisphosphate (PIP(2)). Taken together, these data suggest that the interaction of moesin with the CD93 cytoplasmic domain is modulated by binding of other intracellular molecules to the C11 region and implies that a PIP(2) signalling pathway is involved in CD93 function.

    Funded by: NCI NIH HHS: 5 T32 CO9054, T32 CA009054; NIAID NIH HHS: AI-41090, R01 AI041090

    Immunology 2005;115;1;63-73

  • Human papillomavirus type 18 E6 protein binds the cellular PDZ protein TIP-2/GIPC, which is involved in transforming growth factor beta signaling and triggers its degradation by the proteasome.

    Favre-Bonvin A, Reynaud C, Kretz-Remy C and Jalinot P

    Laboratoire de Biologie Moléculaire de la Cellule, CNRS UMR 5161, Ecole Normale Supérieure de Lyon, Lyon, France.

    Several viral proteins expressed by DNA or RNA transforming viruses have the particular property of binding via their C-terminal end to various cellular proteins with PDZ domains. This study is focused on the PDZ protein TIP-2/GIPC, which was originally identified in two-hybrid screens performed with two different baits: the human T-cell leukemia virus type 1 Tax oncoprotein and the regulator of G signaling RGS-GAIP. Further studies have shown that TIP-2/GIPC is also able to associate with the cytoplasmic domains of various transmembrane proteins. In this report we show that TIP-2/GIPC interacts with the E6 protein of human papillomavirus type 18 (HPV-18). This event triggers polyubiquitination and proteasome-mediated degradation of the cellular protein. In agreement with this observation, silencing of E6 by RNA interference in HeLa cells causes an increase in the intracellular TIP-2/GIPC level. This PDZ protein has been previously found to be involved in transforming growth factor beta (TGF-beta) signaling by favoring expression of the TGF-beta type III receptor at the cell membrane. In line with this activity of TIP-2/GIPC, we observed that depletion of this protein in HeLa cells hampers induction of the Id3 gene by TGF-beta treatment and also diminishes the antiproliferative effect of this cytokine. Conversely, silencing of E6 increases the expression of Id3 and blocks proliferation of HeLa cells. These results support the notion that HPV-18 E6 renders cells less sensitive to the cytostatic effect of TGF-beta by lowering the intracellular amount of TIP-2/GIPC.

    Journal of virology 2005;79;7;4229-37

  • CD93 interacts with the PDZ domain-containing adaptor protein GIPC: implications in the modulation of phagocytosis.

    Bohlson SS, Zhang M, Ortiz CE and Tenner AJ

    Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. sbohlson@uci.edu

    CD93 was originally identified as a myeloid cell-surface marker and subsequently associated with an ability to modulate phagocytosis of suboptimally opsonized immunoglobulin G and complement particles in vitro. Recent studies using mice deficient in CD93 have demonstrated that this molecule modulates phagocytosis of apoptotic cells in vivo. To investigate signal transduction mechanisms mediated by CD93, CD93 cytoplasmic tail (CYTO)-binding proteins were identified in a yeast two-hybrid screen. Fifteen of 34 positive clones contained a splice variant or a partial cDNA encoding GIPC, a PSD-95/Dlg/ZO-1 (PDZ) domain-containing protein, shown previously to regulate cytoskeletal dynamics. A single clone of the N-terminal kinase-like protein p105 and an uncharacterized stem cell transcript also showed specificity for binding to the CYTO by yeast two-hybrid. Using the yeast two-hybrid system and an in vitro glutathione S-transferase fusion protein-binding assay, the binding of GIPC to the CYTO was shown to involve a newly identified class I PDZ-binding domain in the CD93 carboxyl terminus. Four positively charged amino acids in the juxtamembrane domain of CD93 were shown to be critical in stabilizing these interactions. Treatment of human monocytes with a cell-permeable peptide encoding the C-terminal 11 amino acids of CD93 resulted in an enhancement of phagocytosis, supporting the hypothesis that this protein-protein interaction domain is involved in the modulation of phagocytosis. These protein interactions may participate as molecular switches in modulating cellular phagocytic activity.

    Funded by: NCI NIH HHS: 5T32 CA 09054; NIAID NIH HHS: AI-41090

    Journal of leukocyte biology 2005;77;1;80-9

  • GIPC recruits GAIP (RGS19) to attenuate dopamine D2 receptor signaling.

    Jeanneteau F, Guillin O, Diaz J, Griffon N and Sokoloff P

    Unité de Neurobiologie et Pharmacologie Moléculaire, Institut National de la Santé et de la Recherche Médicale, U 573, Centre Paul Broca, 75104 Paris, France. jeannet@broca.inserm.fr

    Pleiotropic G proteins are essential for the action of hormones and neurotransmitters and are activated by stimulation of G protein-coupled receptors (GPCR), which initiates heterotrimer dissociation of the G protein, exchange of GDP for GTP on its Galpha subunit and activation of effector proteins. Regulator of G protein signaling (RGS) proteins regulate this cascade and can be recruited to the membrane upon GPCR activation. Direct functional interaction between RGS and GPCR has been hypothesized. We show that recruitment of GAIP (RGS19) by the dopamine D2 receptor (D2R), a GPCR, required the scaffold protein GIPC (GAIP-interacting protein, C terminus) and that all three were coexpressed in neurons and neuroendocrine cells. Dynamic translocation of GAIP to the plasma membrane and coassembly in a protein complex in which GIPC was a required component was dictated by D2R activation and physical interactions. In addition, two different D2R-mediated responses were regulated by the GTPase activity of GAIP at the level of the G protein coupling in a GIPC-dependent manner. Since GIPC exclusively interacted with GAIP and selectively with subsets of GPCR, this mechanism may serve to sort GPCR signaling in cells that usually express a large repertoire of GPCRs, G proteins, and RGS.

    Molecular biology of the cell 2004;15;11;4926-37

  • 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

  • Synectin in the nervous system: expression pattern and potential as a binding partner of neurotrophin receptors.

    Kato H, Ohno K, Hashimoto K and Sato K

    Department of Anatomy and Neuroscience, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan.

    To assess the potential for functional interaction between synectin and neurotrophin receptors (Trk receptors) in the nervous system, we characterized synectin expression in the rat brain. Synectin is widely expressed in the brain and its expression levels are regulated both temporally and spatially, correlating with those of Trk receptors. Biochemical studies indicated that synectin interacts with TrkB but not with TrkC in the developing brain. We also found that axotomized motoneurons upregulate synectin mRNA expression as well as TrkB mRNA. These data suggest that synectin plays a role in neural development and regeneration in association with TrkB.

    FEBS letters 2004;572;1-3;123-8

  • A protein interaction framework for human mRNA degradation.

    Lehner B and Sanderson CM

    MRC Rosalind Franklin Centre for Genomics Research, Hinxton, Cambridge CB10 1SB, United Kingdom.

    The degradation of mRNA is an important regulatory step in the control of gene expression. However, mammalian RNA decay pathways remain poorly characterized. To provide a framework for studying mammalian RNA decay, a two-hybrid protein interaction map was generated using 54 constructs from 38 human proteins predicted to function in mRNA decay. The results provide evidence for interactions between many different proteins required for mRNA decay. Of particular interest are interactions between the poly(A) ribonuclease and the exosome and between the Lsm complex, decapping factors, and 5'-->3' exonucleases. Moreover, multiple interactions connect 5'-->3' and 3'-->5' decay proteins to each other and to nonsense-mediated decay factors, providing the opportunity for coordination between decay pathways. The interaction network also predicts the internal organization of the exosome and Lsm complexes. Additional interactions connect mRNA decay factors to many novel proteins and to proteins required for other steps in gene expression. These results provide an experimental insight into the organization of proteins required for mRNA decay and their coupling to other cellular processes, and the physiological relevance of many of these interactions are supported by their evolutionary conservation. The interactions also provide a wealth of hypotheses to guide future research on mRNA degradation and demonstrate the power of exhaustive protein interaction mapping in aiding understanding of uncharacterized protein complexes and pathways.

    Genome research 2004;14;7;1315-23

  • Interactions of GIPC with dopamine D2, D3 but not D4 receptors define a novel mode of regulation of G protein-coupled receptors.

    Jeanneteau F, Diaz J, Sokoloff P and Griffon N

    Unité de Neurobiologie et Pharmacologie Moléculaire INSERM U 573, Centre Paul Broca, 75014 Paris, France. jeannet@broca.inserm.fr

    The C-terminus domain of G protein-coupled receptors confers a functional cytoplasmic interface involved in protein association. By screening a rat brain cDNA library using the yeast two-hybrid system with the C-terminus domain of the dopamine D(3) receptor (D(3)R) as bait, we characterized a new interaction with the PDZ domain-containing protein, GIPC (GAIP interacting protein, C terminus). This interaction was specific for the dopamine D(2) receptor (D(2)R) and D(3)R, but not for the dopamine D(4) receptor (D(4)R) subtype. Pull-down and affinity chromatography assays confirmed this interaction with recombinant and endogenous proteins. Both GIPC mRNA and protein are widely expressed in rat brain and together with the D(3)R in neurons of the islands of Calleja at plasma membranes and in vesicles. GIPC reduced D(3)R signaling, cointernalized with D(2)R and D(3)R, and sequestered receptors in sorting vesicles to prevent their lysosomal degradation. Through its dimerization, GIPC acts as a selective scaffold protein to assist receptor functions. Our results suggest a novel function for GIPC in the maintenance, trafficking, and signaling of GPCRs.

    Molecular biology of the cell 2004;15;2;696-705

  • 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

  • GIPC binds to the human lutropin receptor (hLHR) through an unusual PDZ domain binding motif, and it regulates the sorting of the internalized human choriogonadotropin and the density of cell surface hLHR.

    Hirakawa T, Galet C, Kishi M and Ascoli M

    Department of Pharmacology, the University of Iowa, Iowa City, Iowa 52242, USA.

    By using a yeast two-hybrid screen we identified GIPC (GAIP-interacting protein C terminus), a protein with a type I PDZ domain as a novel human lutropin receptor (hLHR) binding partner. Pull-down and immunoprecipitation assays confirmed this interaction and showed that it is dependent on the PDZ domain of GIPC and the C-terminal tetrapeptide of the hLHR. To characterize the functional consequences of the GIPC-hLHR interaction, we used a small interfering RNA against GIPC to generate a clonal cell line that is deficient in GIPC. Studies with this cell line reveal that GIPC is partially responsible for the recycling of the hormone that is internalized by the hLHR and also for maintaining a relatively constant level of hLHR at the cell surface during hormone internalization.

    Funded by: NCI NIH HHS: CA 40629

    The Journal of biological chemistry 2003;278;49;49348-57

  • CLIC6, a member of the intracellular chloride channel family, interacts with dopamine D(2)-like receptors.

    Griffon N, Jeanneteau F, Prieur F, Diaz J and Sokoloff P

    Unité de Neurobiologie et Pharmacologie Moléculaire, INSERM U-573, Centre Paul Broca, 2ter Rue d'Alésia, 75014, Paris, France. nathalie.griffon@broca.inserm.fr

    To identify proteins interacting with the C-terminal cytoplasmic tail of the dopamine D(3) receptor (D(3)R), we used the two-hybrid system to screen a rat brain cDNA library. We isolated three partial cDNAs encoding, respectively, for the MUPP1 multi-PDZ protein, for the N-terminal region of radixin, for GIPC and for a 160-amino acid open reading frame sharing high homology with the human CLIC6, also identified as parchorin in rabbit. In the two-hybrid system, CLIC6 was also able to interact with the D(2)R and D(4)R. The interaction between D(3)R and CLIC6 was confirmed by the use of a GST-D(3)R C-terminus fusion protein and COS cell extracts transiently expressing epitope-tagged CLIC6. In adult rat brain, CLIC6 mRNA expression was restricted to the choroid plexus, the striatal proliferative subventricular zone and the cerebellum where it is co-expressed with the D(3)R in the Purkinje cells of the lobules IX and X. CLIC6 mRNA was also detected in the pituitary in the posterior lobe and in cells co-expressing the D(2)R at the border between the intermediate and anterior lobes. In transfected HEK293 cells, D(3)R and CLIC6 co-localized at the plasma-membrane. No effect of CLIC6 transfection was observed on either intracellular chloride concentration or D(3)R/D(2)R-mediated response. In two-hybrid system, CLIC6 also interacted with MUPP1 and radixin but not GIPC, suggesting it could take part in a complex with D(2)-like receptors, not only by direct interaction with their C-termini, but also through interactions with scaffolding proteins.

    Brain research. Molecular brain research 2003;117;1;47-57

  • Myosin VI: two distinct roles in endocytosis.

    Hasson T

    Division of Biological Sciences, Section of Cell and Developmental Biology, University of California at San Diego, 2129 Bonner Hall, MC 0368, 9500 Gilman Drive, La Jolla, CA 92093-0368, USA. tama@ucsd.edu

    Actin is found at the cortex of the cell where endocytosis occurs, but does it play a role in this essential process? Recent studies on the unconventional myosin, myosin VI, an actin-based molecular motor, provide compelling evidence that this myosin and therefore actin is involved in two distinct steps of endocytosis in higher eukaryotes: the formation of clathrin-coated vesicles and the movement of nascent uncoated vesicles from the actin-rich cell periphery to the early endosome. Three distinct adapter proteins--GIPC, Dab2 and SAP97--that associate with the cargo-binding tail domain of myosin VI have been identified. These proteins may recruit myosin VI to its sites of action.

    Journal of cell science 2003;116;Pt 17;3453-61

  • GIPC interacts with the beta1-adrenergic receptor and regulates beta1-adrenergic receptor-mediated ERK activation.

    Hu LA, Chen W, Martin NP, Whalen EJ, Premont RT and Lefkowitz RJ

    Howard Hughes Medical Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.

    Beta1-adrenergic receptors, expressed at high levels in the human heart, have a carboxyl-terminal ESKV motif that can directly interact with PDZ domain-containing proteins. Using the beta1-adrenergic receptor carboxyl terminus as bait, we identified the novel beta1-adrenergic receptor-binding partner GIPC in a yeast two-hybrid screen of a human heart cDNA library. Here we demonstrate that the PDZ domain-containing protein, GIPC, co-immunoprecipitates with the beta1-adrenergic receptor in COS-7 cells. Essential for this interaction is the Ser residue of the beta1-adrenergic receptor carboxyl-terminal ESKV motif. Our data also demonstrate that beta1-adrenergic receptor stimulation activates the mitogen-activated protein kinase, ERK1/2. beta1-adrenergic receptor-mediated ERK1/2 activation was inhibited by pertussis toxin, implicating Gi, and was substantially decreased by the expression of GIPC. Expression of GIPC had no observable effect on beta1-adrenergic receptor sequestration or receptor-mediated cAMP accumulation. This GIPC effect was specific for the beta1-adrenergic receptor and was dependent on an intact PDZ binding motif. These data suggest that GIPC can regulate beta1-adrenergic receptor-stimulated, Gi-mediated, ERK activation while having no effect on receptor internalization or Gs-mediated cAMP signaling.

    Funded by: NHLBI NIH HHS: HL16037

    The Journal of biological chemistry 2003;278;28;26295-301

  • Myo6 facilitates the translocation of endocytic vesicles from cell peripheries.

    Aschenbrenner L, Lee T and Hasson T

    Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093, USA.

    Immunolocalization studies in epithelial cells revealed myo6 was associated with peripherally located vesicles that contained the transferrin receptor. Pulse-chase experiments after transferrin uptake showed that these vesicles were newly uncoated endocytic vesicles and that myo6 was recruited to these vesicles immediately after uncoating. GIPC, a putative myo6 tail binding protein, was also present. Myo6 was not present on early endosomes, suggesting that myo6 has a transient association with endocytic vesicles and is released upon early endosome fusion. Green fluorescent protein (GFP) fused to myo6 as well as the cargo-binding tail (M6tail) alone targeted to the nascent endocytic vesicles. Overexpression of GFP-M6tail had no effect on a variety of organelle markers; however, GFP-M6tail displaced the endogenous myo6 from nascent vesicles and resulted in a significant delay in transferrin uptake. Pulse-chase experiments revealed that transferrin accumulated in uncoated vesicles within the peripheries of transfected cells and that Rab5 was recruited to the surface of these vesicles. Given sufficient time, the transferrin did traffic to the perinuclear sorting endosome. These data suggest that myo6 is an accessory protein required for the efficient transportation of nascent endocytic vesicles from the actin-rich peripheries of epithelial cells, allowing for timely fusion of endocytic vesicles with the early endosome.

    Molecular biology of the cell 2003;14;7;2728-43

  • Functional interaction of megalin with the megalinbinding protein (MegBP), a novel tetratrico peptide repeat-containing adaptor molecule.

    Petersen HH, Hilpert J, Militz D, Zandler V, Jacobsen C, Roebroek AJ and Willnow TE

    Max-Delbrueck-Center for Molecular Medicine and Medical Faculty of the Free University of Berlin, Germany.

    Megalin is a member of the LDL receptor gene family that plays an important role in forebrain development and in cellular vitamin D metabolism through endocytic uptake of vitamin D metabolites. Similar to other receptors in this gene family, megalin is believed to functionally interact with intracellular proteins through adaptors that bind to the receptor tail and regulate its endocytic and signal transducing activities. Using yeast two-hybrid screens, we identified a novel scaffold protein with tetratrico peptide repeats, the megalin-binding protein (MegBP) that associates with the receptor. The binding site of MegBP was mapped to an N-terminal region on the receptor tail harboring a proline-rich peptide element. MegBP binding did not block the endocytic activity of the receptor; however, overexpression resulted in cellular lethality. In further screens, we identified proteins that bound to MegBP and thus might be recruited to the megalin tail. MegBP-interacting partners included several transcriptional regulators such as the SKI-interacting protein (SKIP), a co-activator of the vitamin D receptor. These finding suggest a model whereby megalin directly participates in transcriptional regulation through controlled sequestration or release of transcription factors via MegBP.

    Journal of cell science 2003;116;Pt 3;453-61

  • GIPC gene family (Review).

    Katoh M

    Genetics and Cell Biology Section, Genetics Division, National Cancer Center Research Institute, Tsukiji 5-chome, Chuo-ku, Tokyo 104-0045, Japan. mkatoh@ncc.go.jp

    GIPC1/GIPC/RGS19IP1, GIPC2, and GIPC3 genes constitute the human GIPC gene family. GIPC1 and GIPC2 show 62.0% total-amino-acid identity. GIPC1 and GIPC3 show 59.9% total-amino-acid identity. GIPC2 and GIPC3 show 55.3% total-amino-acid identity. GIPCs are proteins with central PDZ domain and GIPC homology (GH1 and GH2) domains. PDZ, GH1, and GH2 domains are conserved among human GIPCs, Xenopus GIPC/Kermit, and Drosophila GIPC/ LP09416. Bioinformatics revealed that GIPC genes are linked to prostanoid receptor genes and DNAJB genes in the human genome as follows: GIPC1 gene is linked to prostaglandin E receptor 1 (PTGER1) gene and DNAJB1 gene in human chromosome 19p13.2-p13.1 region; GIPC2 gene to prostaglandin F receptor (PTGFR) gene and DNAJB4 gene in human chromosome 1p31.1-p22.3 region; GIPC3 gene to thromboxane A2 receptor (TBXA2R) gene in human chromosome 19p13.3 region. GIPC1 and GIPC2 mRNAs are expressed together in OKAJIMA, TMK1, MKN45 and KATO-III cells derived from diffuse-type of gastric cancer, and are up-regulated in several cases of primary gastric cancer. PDZ domain of GIPC family proteins interact with Frizzled-3 (FZD3) class of WNT receptor, insulin-like growth factor-I (IGF1) receptor, receptor tyrosine kinase TrkA, TGF-beta type III receptor (TGF-beta RIII), integrin alpha6A subunit, transmembrane glycoprotein 5T4, and RGS19/RGS-GAIP. Because RGS19 is a member of the RGS family that regulate heterotrimeric G-protein signaling, GIPCs might be scaffold proteins linking heterotrimeric G-proteins to seven-transmembrane-type WNT receptor or to receptor tyrosine kinases. Therefore, GIPC1, GIPC2 and GIPC3 might play key roles in carcinogenesis and embryogenesis through modulation of growth factor signaling and cell adhesion.

    International journal of molecular medicine 2002;9;6;585-9

  • Expression of human GIPC1 in normal tissues, cancer cell lines, and primary tumors.

    Kirikoshi H and Katoh M

    Genetics and Cell Biology Section, Genetics Division, National Cancer Center Research Institute, Tsukuji 5-chome, Chuo-ku, Tokyo 104-0045, Japan.

    GIPC1/RGS19IP1/GIPC, GIPC2, and GIPC3 are a family of central PDZ-domain proteins with GH1 and GH2 domains. GIPC1 interacts with GTPase-activating protein RGS19/RGS-GAIP, TGFbeta type III receptor, receptor tyrosine kinase TrkA, and integrin alpha6A subunit. Xenopus homologue of human GIPCs interacts with Frizzled-3 class of WNT receptor. We investigated expression of human GIPC1 mRNA in normal tissues, cancer cell lines, and primary tumors. GIP1A probe (nucleotide position 1075-1483 of GIPC1 cDNA) hybridized to GIPC1 mRNA of 1.8 kb in size. GIPC1 mRNA was almost ubiquitously expressed in various normal tissues. Expression level of GIPC1 mRNA was relatively lower in bone marrow and peripheral blood leukocytes. GIPC1 mRNA was relatively highly expressed in gastric cancer cell lines OKAJIMA, TMK1, MKN28, MKN45, MKN74, KATO-III, pancreatic cancer cell line AsPC-1, colorectal cancer cell line SW480, and lung cancer cell line A549. On the other hand, GIPC1 mRNA was almost undetectable in leukemia/lymphoma cell lines HL-60, Raji, and Daudi. Expression of GIPC1 mRNA was down-regulated in 12 out of 14 cases of primary kidney tumors, 10 out of 18 cases of primary colorectal tumors, 3 out of 8 cases of primary gastric cancer, 3 out of 3 cases of primary prostate cancer. Because GIPC1 induces increased expression of TGFbeta type III receptor at the cell surface and enhanced responsiveness to TGFbeta, down-regulation of GIPC1 mRNA in tumors might promote cellular proliferation through interference of TGFbeta signaling.

    International journal of molecular medicine 2002;9;5;509-13

  • GAIP, GIPC and Galphai3 are concentrated in endocytic compartments of proximal tubule cells: putative role in regulating megalin's function.

    Lou X, McQuistan T, Orlando RA and Farquhar MG

    Department of Cellular and Molecular Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. mfarquhar@ucsd.edu

    Megalin is the most abundant endocytic receptor in the proximal tubule epithelium (PTE), where it is concentrated in clathrin-coated pits (CCPs) and vesicles in the brush border region. The heterotrimeric G protein alpha subunit, Galphai3, has also been localized to the brush border region of PTE. By immunofluorescence GIPC and GAIP, components of G protein-mediated signaling pathways, are also concentrated in the brush border region of PTE and are present in megalin-expressing cell lines. By cell fractionation, these signaling molecules cosediment with megalin in brush border and microvillar fractions. GAIP is found by immunoelectron microscopy in CCPs, and GIPC is found in CCPs and apical tubules of endocytic compartments in the renal brush border. In precipitation assays, GST-GIPC specifically binds megalin. The concentration of Galphai3, GIPC, and GAIP with megalin in endocytic compartments of the proximal tubule, where extensive endocytosis occurs, and the interaction between GIPC and the cytoplasmic tail of megalin suggest a model whereby G protein-mediated signaling may regulate megalin's endocytic function and/or trafficking.

    Funded by: NIDDK NIH HHS: DK 17724

    Journal of the American Society of Nephrology : JASN 2002;13;4;918-27

  • The PDZ domain of TIP-2/GIPC interacts with the C-terminus of the integrin alpha5 and alpha6 subunits.

    El Mourabit H, Poinat P, Koster J, Sondermann H, Wixler V, Wegener E, Laplantine E, Geerts D, Georges-Labouesse E, Sonnenberg A and Aumailley M

    Institute for Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany.

    Different cDNA libraries were screened by the yeast two-hybrid system using as a bait the cytoplasmic sequence of integrin alpha6A or alpha6B subunits. Surprisingly, the same PDZ domain-containing protein, TIP-2/GIPC, was isolated with either of the variants, although their sequences are different. Direct interaction assays with the cytoplasmic domain of the integrin alpha1--7 subunits revealed that in addition to alpha6A and alpha6B, TIP-2/GIPC reacted also with alpha5, but not other alpha integrin subunits. The specificity of the interaction was confirmed by in vitro protein binding assays with purified peptides corresponding to integrin cytoplasmic domains. Further analysis with either truncation fragments of TIP-2/GIPC or mutated integrin cytoplasmic domains indicated that the interaction occurs between the PDZ domain of TIP-2/GIPC and a consensus PDZ domain-binding sequence, SDA, present at the C-terminus of the integrin alpha5 and alpha6A subunits. The integrin alpha6B subunit terminates with a different sequence, SYS, which may represent a new PDZ domain-binding motif.

    Matrix biology : journal of the International Society for Matrix Biology 2002;21;2;207-14

  • 5T4 interacts with TIP-2/GIPC, a PDZ protein, with implications for metastasis.

    Awan A, Lucic MR, Shaw DM, Sheppard F, Westwater C, Lyons SA and Stern PL

    CRC Immunology Group, CRC Molecular Biology Group, The Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Wilmslow Road, Manchester, M20 4BX, United Kingdom.

    Overexpression of the 5T4 transmembrane glycoprotein can have marked effects on both the actin cytoskeleton and cell migration. Using a yeast two-hybrid approach, we describe a novel interaction between 5T4 and TIP-2/GIPC, a cytoplasmic interacting protein containing a PDZ domain. The cytoplasmic tail of 5T4 contains a class I PDZ-binding motif (Ser-Asp-Val) and we demonstrate that this region, in particular the terminal valine, is required for 5T4 interaction with TIP-2/GIPC. HeLa cells expressing hemagglutinin-tagged TIP-2/GIPC (HA-TIP-2/GIPC) have an altered distribution of endogenous 5T4, which colocalizes with HA-TIP-2/GIPC, thus supporting an interaction. Furthermore, TIP-2/GIPC can be coimmunoprecipitated with 5T4 from HeLa cell lysates. Identification of the 5T4 and TIP-2/GIPC interaction provides the first link between 5T4 and the actin cytoskeleton. Since other proteins, like 5T4, associate with TIP-2/GIPC and are linked with cancer, we explore the possibility that TIP-2/GIPC may be a common factor involved in the cancer process.

    Biochemical and biophysical research communications 2002;290;3;1030-6

  • A novel mechanism for regulating transforming growth factor beta (TGF-beta) signaling. Functional modulation of type III TGF-beta receptor expression through interaction with the PDZ domain protein, GIPC.

    Blobe GC, Liu X, Fang SJ, How T and Lodish HF

    Department of Medicine and Pharmacology, Duke University Medical Center, Durham, NC 27710, USA. blobe001@mc.duke.edu

    Transforming growth factor beta (TGF-beta) mediates its biological effects through three high-affinity cell surface receptors, the TGF-beta type I, type II, and type III receptors, and the Smad family of transcription factors. Although the functions of the type II and type I receptors are well established, the precise role of the type III receptor in TGF-beta signaling remains to be established. While expression cloning signaling molecules downstream of TGF-beta, we cloned GIPC (GAIP-interacting protein, C terminus), a PDZ domain-containing protein. GIPC binds a Class I PDZ binding motif in the cytoplasmic domain of the type III receptor resulting in regulation of expression of the type III receptor at the cell surface. Increased expression of the type III receptor mediated by GIPC enhanced cellular responsiveness to TGF-beta both in terms of inhibition of proliferation and in plasminogen-activating inhibitor (PAI)-based promoter gene induction assays. In all cases, deletion of the Class I PDZ binding motif of the type III receptor prevented the type III receptor from binding to GIPC and abrogated the effects of GIPC on type III receptor expressing cells. These results establish, for the first time, a protein that interacts with the cytoplasmic domain of the type III receptor, determine that expression of the type III receptor is regulated at the protein level and that increased expression of the type III receptor is sufficient to enhance TGF-beta signaling. These results further support an essential, non-redundant role for the type III receptor in TGF-beta signaling.

    Funded by: NCI NIH HHS: CA 63260

    The Journal of biological chemistry 2001;276;43;39608-17

  • PDZ interaction sites in integrin alpha subunits. T14853, TIP/GIPC binds to a type I recognition sequence in alpha 6A/alpha 5 and a novel sequence in alpha 6B.

    Tani TT and Mercurio AM

    Division of Cancer Biology and Angiogenesis, Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.

    We used published peptide library data to identify PDZ recognition sequences in integrin alpha subunit cytoplasmic domains and found that the alpha(6)A and alpha(5) subunits contain a type I PDZ binding site (TSDA*) (asterisk indicates the stop codon). The alpha(6)A cytoplasmic domain was used for screening a two-hybrid library to find interacting proteins. The bulk of the captured cDNAs (60%) coded for TIP-2/GIPC, a cytoplasmic protein with one PDZ domain. The interaction of TIP-2/GIPC with different integrin subunits was tested in two-hybrid and in vitro binding assays. Surprisingly, TIP-2/GIPC bound strongly to the C terminus of both alpha(6)A and alpha(6)B, although the alpha(6)B sequence (ESYS*) is not suggestive of a PDZ binding site because of its polar C-terminal residue. For high affinity interaction with TIP-2/GIPC, at least one of the residues at positions -1 and -3 must be negatively charged. An aliphatic residue at position 0 increases the affinity of but is not required for this interaction. The alpha(5) integrin subunit also bound to TIP-2/GIPC. The alpha(6) integrin and TIP-2/GIPC co-localize in retraction fibers in carcinoma cells plated on laminin, a finding suggesting a functional interaction in vivo. Our results demonstrate that both splice variants of alpha(6) integrin contain a conserved PDZ binding site that enables interaction with TIP-2/GIPC. The binding site in alpha(6)B defines a new subclass of type I PDZ interaction site, characterized by a non-aliphatic residue at position 0.

    Funded by: NCI NIH HHS: CA80789; NIAID NIH HHS: AI39264

    The Journal of biological chemistry 2001;276;39;36535-42

  • PDZ domain protein GIPC interacts with the cytoplasmic tail of melanosomal membrane protein gp75 (tyrosinase-related protein-1).

    Liu TF, Kandala G and Setaluri V

    Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.

    Tyrosinase and tyrosinase-related proteins (TRPs) are a family of melanosomal membrane proteins involved in mammalian pigmentation. Whereas the melanogenic functions of TRPs are localized in their amino-terminal domains that reside within the lumen of melanosomes, the sorting and targeting of these proteins to melanosomes is mediated by signals in their cytoplasmic domains. To identify proteins that interact with the cytoplasmic tail of gp75 (TRP-1), the most abundant melanosomal membrane protein, we performed yeast two-hybrid screening of a melanocyte cDNA library. Here, we show that the cytoplasmic domain of gp75 interacts with a PDZ domain-containing protein. The gp75-interacting protein is identical to GIPC, an RGS (regulator of G protein signaling)/GAIP-interacting protein, and to SEMCAP-1, a transmembrane semaphorin-binding protein. Carboxyl-terminal amino acid residues, Ser-Val-Val, of gp75 are necessary and sufficient for interaction of gp75 with the single PDZ domain in GIPC. Although endogenous and transfected GIPCs bind efficiently to transiently expressed gp75, only a small amount of GIPC is found associated with gp75 at steady state. Using a strategy to selectively synchronize the biosynthesis of endogenous gp75, we demonstrate that only newly synthesized gp75 associates with GIPC, primarily in the juxtanuclear Golgi region. Our data suggest that GIPC/SEMCAP-1 plays a role in biosynthetic sorting of proteins, specifically gp75, to melanosomes.

    Funded by: NIAMS NIH HHS: AR41465, AR44617

    The Journal of biological chemistry 2001;276;38;35768-77

  • A PDZ domain protein interacts with the C-terminal tail of the insulin-like growth factor-1 receptor but not with the insulin receptor.

    Ligensa T, Krauss S, Demuth D, Schumacher R, Camonis J, Jaques G and Weidner KM

    Roche Diagnostics GmbH, Pharma Research, Nonnenwald 2, Penzberg 82372, Germany.

    In this study, we report on the isolation of a PDZ domain protein, here designated as IIP-1, insulin-like growth factor-1 (IGF-1) receptor-interacting protein-1, which binds to the IGF-1 receptor, but not to the related insulin receptor, and which is involved in the regulation of cell motility. The interaction between the IGF-1 receptor and IIP-1 as well as a splice variant IIP-1/p26 was demonstrated in the yeast two-hybrid system. Using co-precipitation experiments, we confirmed the interaction in transfected cells as well as in vitro. Analysis of deletion mutants indicates that the PDZ domain of IIP-1 mediates interaction with the C-terminal tail of the IGF-1 receptor (serine-threonine-cysteine). This finding demonstrates that the C terminus of the IGF-1 receptor acts as novel PDZ domain binding site. Immunofluorescence analysis revealed an overlapping localization of IIP-1 and the IGF-1 receptor in the breast cancer cell line MCF-7. A functional connection between IIP-1 and the IGF-1 receptor is further supported by the finding that the level of expression of IIP-1 and the IGF-1 receptor strongly correlates in different normal and cancer cells. Furthermore, overexpression of IIP-1 resulted in an attenuation of migration of MCF-7 cells, which is one of the biological activities mediated by the IGF-1 signaling system.

    The Journal of biological chemistry 2001;276;36;33419-27

  • GIPC and GAIP form a complex with TrkA: a putative link between G protein and receptor tyrosine kinase pathways.

    Lou X, Yano H, Lee F, Chao MV and Farquhar MG

    Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA.

    NGF initiates the majority of its neurotrophic effects by promoting the activation of the tyrosine kinase receptor TrkA. Here we describe a novel interaction between TrkA and GIPC, a PDZ domain protein. GIPC binds to the juxtamembrane region of TrkA through its PDZ domain. The PDZ domain of GIPC also interacts with GAIP, an RGS (regulators of G protein signaling) protein. GIPC and GAIP are components of a G protein-coupled signaling complex thought to be involved in vesicular trafficking. In transfected HEK 293T cells GIPC, GAIP, and TrkA form a coprecipitable protein complex. Both TrkA and GAIP bind to the PDZ domain of GIPC, but their binding sites within the PDZ domain are different. The association of endogenous GIPC with the TrkA receptor was confirmed by coimmunoprecipitation in PC12 (615) cells stably expressing TrkA. By immunofluorescence GIPC colocalizes with phosphorylated TrkA receptors in retrograde transport vesicles located in the neurites and cell bodies of differentiated PC12 (615) cells. These results suggest that GIPC, like other PDZ domain proteins, serves to cluster transmembrane receptors with signaling molecules. When GIPC is overexpressed in PC12 (615) cells, NGF-induced phosphorylation of mitogen-activated protein (MAP) kinase (Erk1/2) decreases; however, there is no effect on phosphorylation of Akt, phospholipase C-gamma1, or Shc. The association of TrkA receptors with GIPC and GAIP plus the inhibition of MAP kinase by GIPC suggests that GIPC may provide a link between TrkA and G protein signaling pathways.

    Funded by: NCI NIH HHS: CA-58689; NICHD NIH HHS: HD-23315, P01 HD023315; NIDDK NIH HHS: DK-17780, R01 DK017780; NINDS NIH HHS: NS-21072, R01 NS021072, R56 NS021072

    Molecular biology of the cell 2001;12;3;615-27

  • Synectin, syndecan-4 cytoplasmic domain binding PDZ protein, inhibits cell migration.

    Gao Y, Li M, Chen W and Simons M

    Angiogenesis Research Center, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.

    Syndecan-4, a member of the syndecan gene family of proteoglycans, is an important regulator of bFGF signaling. In particular, bFGF-dependent regulation of cell growth and migration has been linked to syndecan-4 cytoplasmic domain-mediated interactions. Screening of a yeast two-hybrid library with a cytoplasmic domain of rat syndecan-4 identified a novel binding partner, here termed synectin. Synectin is highly homologous to semaphorin F binding protein semcap1, glucose 1 transporter binding protein glut1cbp, and RGS-GAIP/neuropilin-1 binding protein GIPC. Overexpression of synectin in ECV304 cells in culture led to a dose-dependent inhibition of migration while not affecting cell adhesion or growth rate. We conclude that synectin is involved in syndecan-4-dependent interactions and may play a role in the assembly of syndecan-4 signaling complex.

    Funded by: NHLBI NIH HHS: P50 HL 56993, R01 HL62289

    Journal of cellular physiology 2000;184;3;373-9

  • Interactions of the low density lipoprotein receptor gene family with cytosolic adaptor and scaffold proteins suggest diverse biological functions in cellular communication and signal transduction.

    Gotthardt M, Trommsdorff M, Nevitt MF, Shelton J, Richardson JA, Stockinger W, Nimpf J and Herz J

    Department of Molecular Genetics and Pathology, University of Texas Southwestern Medical Center, Dallas 75390-9046, USA.

    The members of the low density lipoprotein (LDL) receptor gene family bind a broad spectrum of extracellular ligands. Traditionally, they had been regarded as mere cargo receptors that promote the endocytosis and lysosomal delivery of these ligands. However, recent genetic experiments in mice have revealed critical functions for two LDL receptor family members, the very low density lipoprotein receptor and the apoE receptor-2, in the transmission of extracellular signals and the activation of intracellular tyrosine kinases. This process regulates neuronal migration and is crucial for brain development. Signaling through these receptors requires the interaction of their cytoplasmic tails with the intracellular adaptor protein Disabled-1 (DAB1). Here, we identify an extended set of cytoplasmic proteins that might also participate in signal transmission by the LDL receptor gene family. Most of these novel proteins are adaptor or scaffold proteins that contain PID or PDZ domains and function in the regulation of mitogen-activated protein kinases, cell adhesion, vesicle trafficking, or neurotransmission. We show that binding of DAB1 interferes with receptor internalization suggesting a mechanism by which signaling through this class of receptors might be regulated. Taken together, these findings imply much broader physiological functions for the LDL receptor family than had previously been appreciated. They form the basis for the elucidation of the molecular pathways by which cells respond to the diversity of ligands that bind to these multifunctional receptors on the cell surface.

    Funded by: NHLBI NIH HHS: HL20948, HL63762, R37 HL063762

    The Journal of biological chemistry 2000;275;33;25616-24

  • Assignment of PDZ domain-containing protein GIPC gene (C19orf3) to human chromosome band 19p13.1 by in situ hybridization and radiation hybrid mapping.

    Von Kap-Herr C, Kandala G, Mann SS, Hart TC, Pettenati MJ and Setaluri V

    Department of Pediatrics, Section on Medical Genetics, Wake Forest University School of Medicine, Winston-Salem, NC, USA.

    Funded by: NIAMS NIH HHS: AR 4144617; NIDCR NIH HHS: DE 12202

    Cytogenetics and cell genetics 2000;89;3-4;234-5

  • Cloning and characterization of neuropilin-1-interacting protein: a PSD-95/Dlg/ZO-1 domain-containing protein that interacts with the cytoplasmic domain of neuropilin-1.

    Cai H and Reed RR

    Howard Hughes Medical Institutes, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

    Neuropilin-1 (Npn-1), a receptor for semaphorin III, mediates the guidance of growth cones on extending neurites. The molecular mechanism of Npn-1 signaling remains unclear. We have used a yeast two-hybrid system to isolate a protein that interacts with the cytoplasmic domain of Npn-1. This Npn-1-interacting protein (NIP) contains a central PSD-95/Dlg/ZO-1 (PDZ) domain and a C-terminal acyl carrier protein domain. The physiological interaction of Npn-1 and NIP is supported by co-immunoprecipitation of these two proteins in extracts from a heterologous expression system and from a native tissue. The C-terminal three amino acids of Npn-1 (S-E-A-COOH), which is conserved from Xenopus to human, is responsible for interaction with the PDZ domain-containing C-terminal two-thirds of NIP. NIP as well as Npn-1 are broadly expressed in mice as assayed by Northern and Western analysis. Immunohistochemistry and in situ hybridization experiments revealed that NIP expression overlaps with that of Npn-1. NIP has been independently cloned as RGS-GAIP-interacting protein (GIPC), where it was identified by virtue of its interaction with the C terminus of RGS-GAIP and suggested to participate in clathrin-coated vesicular trafficking. We suggest that NIP and GIPC may participate in regulation of Npn-1-mediated signaling as a molecular adapter that couples Npn-1 to membrane trafficking machinery in the dynamic axon growth cone.

    The Journal of neuroscience : the official journal of the Society for Neuroscience 1999;19;15;6519-27

  • A PDZ protein regulates the distribution of the transmembrane semaphorin, M-SemF.

    Wang LH, Kalb RG and Strittmatter SM

    Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.

    M-SemF is a membrane-associated, neurally enriched member of the semaphorin family of axon guidance signals. We considered whether the cytoplasmic domain of M-SemF might possess a signaling function and/or might control the distribution of M-SemF on the cell surface. We identify a PDZ-containing neural protein as an M-SemF cytoplasmic domain-associated protein (SEMCAP-1). SEMCAP-2 is a closely related nonneuronal protein. SEMCAP-1 has recently also been identified as GIPC, by virtue of its interaction with the RGS protein GAIP in vitro (De Vries, L., Lou, X., Zhao, G., Zheng, B., and Farquhar, M. G. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 12340-12345). Expression studies support the notion that SEMCAP-1(GIPC) interacts with M-SemF, but not GAIP, in brain. Lung SEMCAP-2 and SEMCAP-1(GIPC) are potential partners for both GAIP and M-SemF. The protein interaction requires the single PDZ domain of SEMCAP-1(GIPC) and the carboxyl-terminal four residues of M-SemF, ESSV. While SEMCAP-1(GIPC) also interacts with SemC, it does not interact with other proteins containing a class I PDZ binding motif, nor does M-SemF interact with other class I PDZ proteins. Co-expression of SEMCAP-1(GIPC) induces the redistribution of dispersed M-SemF into detergent-resistant aggregates in HEK293 cells. Thus, SEMCAP-1(GIPC) appears to regulate the subcellular distribution of M-SemF in brain, and SEMCAPs could link M-SemF to G protein signal transduction pathways.

    Funded by: NINDS NIH HHS: NS29837, NS33020

    The Journal of biological chemistry 1999;274;20;14137-46

  • Protein interactions with the glucose transporter binding protein GLUT1CBP that provide a link between GLUT1 and the cytoskeleton.

    Bunn RC, Jensen MA and Reed BC

    The Department of Biochemistry and Molecular Biology, Louisiana State University School of Medicine, Shreveport, Louisiana 71130-3932, USA.

    Subcellular targeting and the activity of facilitative glucose transporters are likely to be regulated by interactions with cellular proteins. This report describes the identification and characterization of a protein, GLUT1 C-terminal binding protein (GLUT1CBP), that binds via a PDZ domain to the C terminus of GLUT1. The interaction requires the C-terminal four amino acids of GLUT1 and is isoform specific because GLUT1CBP does not interact with the C terminus of GLUT3 or GLUT4. Most rat tissues examined contain both GLUT1CBP and GLUT1 mRNA, whereas only small intestine lacked detectable GLUT1CBP protein. GLUT1CBP is also expressed in primary cultures of neurons and astrocytes, as well as in Chinese hamster ovary, 3T3-L1, Madin-Darby canine kidney, Caco-2, and pheochromocytoma-12 cell lines. GLUT1CBP is able to bind to native GLUT1 extracted from cell membranes, self-associate, or interact with the cytoskeletal proteins myosin VI, alpha-actinin-1, and the kinesin superfamily protein KIF-1B. The presence of a PDZ domain places GLUT1CBP among a growing family of structural and regulatory proteins, many of which are localized to areas of membrane specialization. This and its ability to interact with GLUT1 and cytoskeletal proteins implicate GLUT1CBP in cellular mechanisms for targeting GLUT1 to specific subcellular sites either by tethering the transporter to cytoskeletal motor proteins or by anchoring the transporter to the actin cytoskeleton.

    Molecular biology of the cell 1999;10;4;819-32

  • GIPC, a PDZ domain containing protein, interacts specifically with the C terminus of RGS-GAIP.

    De Vries L, Lou X, Zhao G, Zheng B and Farquhar MG

    Division of Cellular and Molecular Medicine and Department of Pathology, University of California at San Diego, La Jolla, CA 92093-0651, USA.

    We have identified a mammalian protein called GIPC (for GAIP interacting protein, C terminus), which has a central PDZ domain and a C-terminal acyl carrier protein (ACP) domain. The PDZ domain of GIPC specifically interacts with RGS-GAIP, a GTPase-activating protein (GAP) for Galphai subunits recently localized on clathrin-coated vesicles. Analysis of deletion mutants indicated that the PDZ domain of GIPC specifically interacts with the C terminus of GAIP (11 amino acids) in the yeast two-hybrid system and glutathione S-transferase (GST)-GIPC pull-down assays, but GIPC does not interact with other members of the RGS (regulators of G protein signaling) family tested. This finding is in keeping with the fact that the C terminus of GAIP is unique and possesses a modified C-terminal PDZ-binding motif (SEA). By immunoblotting of membrane fractions prepared from HeLa cells, we found that there are two pools of GIPC-a soluble or cytosolic pool (70%) and a membrane-associated pool (30%). By immunofluorescence, endogenous and GFP-tagged GIPC show both a diffuse and punctate cytoplasmic distribution in HeLa cells reflecting, respectively, the existence of soluble and membrane-associated pools. By immunoelectron microscopy the membrane pool of GIPC is associated with clusters of vesicles located near the plasma membrane. These data provide direct evidence that the C terminus of a RGS protein is involved in interactions specific for a given RGS protein and implicates GAIP in regulation of additional functions besides its GAP activity. The location of GIPC together with its binding to GAIP suggest that GAIP and GIPC may be components of a G protein-coupled signaling complex involved in the regulation of vesicular trafficking. The presence of an ACP domain suggests a putative function for GIPC in the acylation of vesicle-bound proteins.

    Funded by: NCI NIH HHS: CA 58689; NIDDK NIH HHS: DK 17780, R01 DK017780

    Proceedings of the National Academy of Sciences of the United States of America 1998;95;21;12340-5

  • The C-terminus of the HTLV-1 Tax oncoprotein mediates interaction with the PDZ domain of cellular proteins.

    Rousset R, Fabre S, Desbois C, Bantignies F and Jalinot P

    Laboratoire de Biologie Moléculaire et Cellulaire, Centre national de la Recherche Scientifique UMR49, Ecole Normale Supérieure de Lyon, France.

    Infection by HTLV-1 has been correlated with the appearance of various proliferative or degenerative diseases. Some of these disorders have been observed in transgenic mice expressing the Tax protein, which is known to transactivate various viral and cellular promoters through interactions with several transcription factors. In this study we show that the C-terminus of this viral oncoprotein represents a motif permitting binding of Tax to the PDZ domains of several cellular proteins. A two-hybrid screen with Tax as bait indeed yielded complementary DNAs coding for six proteins including PDZ domains. Two of them correspond to truncated forms of the PSD-95 and beta1-syntrophin proteins, another clone codes for a protein homologous to the product of the C. elegans gene lin-7. The other three clones code for new human members of the PDZ family of cellular proteins. The interaction of Tax with the products of these clones was confirmed by immunoprecipitation assays in mammalian cells, and analysis of various mutants of Tax established the importance of the C-terminal amino acids for several of these interactions. These data suggest that Tax could perturb the normal function of targeted cellular proteins by strongly interacting with their PDZ domains.

    Oncogene 1998;16;5;643-54

  • GAIP is membrane-anchored by palmitoylation and interacts with the activated (GTP-bound) form of G alpha i subunits.

    De Vries L, Elenko E, Hubler L, Jones TL and Farquhar MG

    Division of Cellular and Molecular Medicine, University of California at San Diego, La Jolla 92093-0651, USA.

    GAIP (G Alpha Interacting Protein) is a member of the recently described RGS (Regulators of G-protein Signaling) family that was isolated by interaction cloning with the heterotrimeric G-protein G alpha i3 and was recently shown to be a GTPase-activating protein (GAP). In AtT-20 cells stably expressing GAIP, we found that GAIP is membrane-anchored and faces the cytoplasm, because it was not released by sodium carbonate treatment but was digested by proteinase K. When Cos cells were transiently transfected with GAIP and metabolically labeled with [35S]methionine, two pools of GAIP--a soluble and a membrane-anchored pool--were found. Since the N terminus of GAIP contains a cysteine string motif and cysteine string proteins are heavily palmitoylated, we investigated the possibility that membrane-anchored GAIP might be palmitoylated. We found that after labeling with [3H]palmitic acid, the membrane-anchored pool but not the soluble pool was palmitoylated. In the yeast two-hybrid system, GAIP was found to interact specifically with members of the G alpha i subfamily, G alpha i1, G alpha i2, G alpha i3, G alpha z, and G alpha o, but not with members of other G alpha subfamilies, G alpha s, G alpha q, and G alpha 12/13. The C terminus of G alpha i3 is important for binding because a 10-aa C-terminal truncation and a point mutant of G alpha i3 showed significantly diminished interaction. GAIP interacted preferentially with the activated (GTP) form of G alpha i3, which is in keeping with its GAP activity. We conclude that GAIP is a membrane-anchored GAP with a cysteine string motif. This motif, present in cysteine string proteins found on synaptic vesicles, pancreatic zymogen granules, and chromaffin granules, suggests GAIP's possible involvement in membrane trafficking.

    Funded by: NCI NIH HHS: CA58689, F32 CA066289; NIDDK NIH HHS: DK17780, R01 DK017780; NIGMS NIH HHS: GM07752, T32 GM007752

    Proceedings of the National Academy of Sciences of the United States of America 1996;93;26;15203-8

  • A pancreatic cancer-specific expression profile.

    Gress TM, Müller-Pillasch F, Geng M, Zimmerhackl F, Zehetner G, Friess H, Büchler M, Adler G and Lehrach H

    Department of Internal Medicine I, University of Ulm, Germany.

    We present an approach making use of technology established in the context of the genome project to describe a pancreatic cancer-specific expression profile and to identify new potential disease genes or disease-associated-genes. By use of gridded arrays of pancreatic cancer cDNA libraries and differential hybridizations we show that 4% the gridded cDNA library clones contain sequences preferentially expressed in pancreatic cancer. EST-sequencing of 369 distinct (408 total), differentially expressed sequences identified novel genes (32.5%) or homologs to EST-sequences with unknown function (26.3%). Homologies to known genes allow to determine a pancreatic cancer-specific expression profile, which provides for the first time evidence for complex primary and secondary alterations of gene expression responsible for the development of the phenotype of pancreatic cancer cells. In addition this has led to the identification of novel differentially expressed genes, which represent potential oncogenes or disease-associated markers and may be helpful for the development of therapeutic or diagnostic modalities.

    Oncogene 1996;13;8;1819-30

Gene lists (5)

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
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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