G2Cdb::Gene report

Gene id
Gene symbol
Homo sapiens
intersectin 1 (SH3 domain protein)
G00000777 (Mus musculus)

Databases (8)

Curated Gene
OTTHUMG00000065284 (Vega human gene)
ENSG00000205726 (Ensembl human gene)
6453 (Entrez Gene)
1187 (G2Cdb plasticity & disease)
ITSN1 (GeneCards)
602442 (OMIM)
Marker Symbol
HGNC:6183 (HGNC)
Protein Sequence
Q15811 (UniProt)

Synonyms (3)

  • MGC134948
  • MGC134949
  • SH3P17

Literature (46)

Pubmed - other

  • Intersectin 1 forms a complex with adaptor protein Ruk/CIN85 in vivo independently of epidermal growth factor stimulation.

    Nikolaienko O, Skrypkina I, Tsyba L, Fedyshyn Y, Morderer D, Buchman V, de la Luna S, Drobot L and Rynditch A

    Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03680, Ukraine.

    Intersectin 1 (ITSN1) is an adaptor protein involved in clathrin-mediated endocytosis, apoptosis, signal transduction and cytoskeleton organization. Here, we show that ITSN1 forms a complex with adaptor protein Ruk/CIN85, implicated in downregulation of receptor tyrosine kinases. The interaction is mediated by the SH3A domain of ITSN1 and the third or fourth proline-rich blocks of Ruk/CIN85, and does not depend on epidermal growth factor stimulation, suggesting a constitutive association of ITSN1 with Ruk/CIN85. Moreover, both proteins colocalize in MCF-7 cells with their common binding partner, the ubiquitin ligase c-Cbl. The possible biological role of the interaction between ITSN1 and Ruk/CIN85 is discussed.

    Cellular signalling 2009;21;5;753-9

  • Characterisation of the nucleotide exchange factor ITSN1L: evidence for a kinetic discrimination of GEF-stimulated nucleotide release from Cdc42.

    Kintscher C and Groemping Y

    Department of Biomolecular Mechanisms, Max-Planck-Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany.

    Cdc42, a member of the Ras superfamily of small guanine nucleotide binding proteins, plays an important role in regulating the actin cytoskeleton, intracellular trafficking, and cell polarity. Its activation is controlled by guanine nucleotide exchange factors (GEFs), which stimulate the dissociation of bound guanosine-5'-diphosphate (GDP) to allow guanosine-5'-triphosphate (GTP) binding. Here, we investigate the exchange factor activity of the Dbl-homology domain containing constructs of the adaptor protein Intersectin1L (ITSN1L), which is a specific GEF for Cdc42. A detailed kinetic characterisation comparing ITSN1L-mediated nucleotide exchange on Cdc42 in its GTP- versus GDP-bound state reveals a kinetic discrimination for GEF-stimulated dissociation of GTP: The maximum acceleration of the intrinsic mGDP [2'/3'-O-(N-methyl-anthraniloyl)-GDP] release from Cdc42 by ITSN1L is accelerated at least 68,000-fold, whereas the exchange of mGTP [2'/3'-O-(N-methyl-anthraniloyl)-GTP] is stimulated only up to 6000-fold at the same GEF concentration. The selectivity in nucleotide exchange kinetics for GDP over GTP is even more pronounced when a Cdc42 mutant, F28L, is used, which is characterised by fast intrinsic dissociation of nucleotides. We furthermore show that both GTP and Mg2+ ions are required for the interaction with effectors. We suggest a novel model for selective nucleotide exchange residing on a conformational change of Cdc42 upon binding of GTP, which enables effector binding to the Cdc42.GTP complex but, at the same time, excludes efficient modulation by the GEF. The higher exchange activity of ITSN1L towards the GDP-bound conformation of Cdc42 could represent an evolutionary adaptation of this GEF that ensures nucleotide exchange towards the formation of the signalling-active GTP-bound form of Cdc42 and avoids dissociation of the active complex.

    Journal of molecular biology 2009;387;2;270-83

  • SHIP2 associates with intersectin and recruits it to the plasma membrane in response to EGF.

    Xie J, Vandenbroere I and Pirson I

    Institute of Interdisciplinary Research, Free University of Brussels, Route de Lennik 808, B-1070 Brussels, Belgium.

    We identified intersectin1 (ITSN1) as a new binding partner of the SH2 domain containing inositol 5-phosphatase 2 (SHIP2). The interaction between SHIP2 and ITSN1 was confirmed in vivo. Src homology 3D, A, C, and E domains of ITSN1 were shown to be implicated in the interaction. In response to epidermal growth factor, SHIP2 expression could recruit the ITSN1 short form (ITSN1-S) to the cell membrane, while SHIP2 overexpression did not modulate the ITSN-mediated extracellular signal-regulated kinase1/2 and c-Jun NH2-terminal kinase activation. Our data provide a molecular link between SHIP2 and ITSN1 which are involved in receptor endocytosis regulation.

    FEBS letters 2008;582;20;3011-7

  • Alternative splicing affecting the SH3A domain controls the binding properties of intersectin 1 in neurons.

    Tsyba L, Gryaznova T, Dergai O, Dergai M, Skrypkina I, Kropyvko S, Boldyryev O, Nikolaienko O, Novokhatska O and Rynditch A

    Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03143, Ukraine. l.o.tsyba@imbg.org.ua

    Intersectin 1 (ITSN1) is a conserved adaptor protein implicated in endocytosis, regulation of actin cytoskeleton rearrangements and mitogenic signaling. Its expression is characterized by multiple alternative splicing. Here we show neuron-specific expression of ITSN1 isoforms containing exon 20, which encodes five amino acid residues in the first SH3 domain (SH3A). In vitro binding experiments demonstrated that inclusion of exon 20 changes the binding properties of the SH3A domain. Endocytic proteins dynamin 1 and synaptojanin 1 as well as GTPase-activating protein CdGAP bound the neuron-specific variant of the SH3A domain with higher affinity than ubiquitously expressed SH3A. In contrast, SOS1, a guanine nucleotide exchange factor for Ras, and the ubiquitin ligase Cbl mainly interact with the ubiquitously expressed isoform. These results demonstrate that alternative splicing leads to the formation of two pools of ITSN1 with potentially different properties in neurons, affecting ITSN1 function as adaptor protein.

    Biochemical and biophysical research communications 2008;372;4;929-34

  • Intersectin-1s regulates the mitochondrial apoptotic pathway in endothelial cells.

    Predescu SA, Predescu DN, Knezevic I, Klein IK and Malik AB

    Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA. sandap@uic.edu

    Intersectins (ITSNs) are multidomain adaptor proteins implicated in endocytosis, regulation of actin polymerization, and Ras/MAPK signaling. We have previously shown that ITSN-1s is required for caveolae fission and internalization in endothelial cells (ECs). In the present study, using small interfering RNA to knock down ITSN-1s protein expression, we demonstrate a novel role of ITSN-1s as a key antiapoptotic protein. Knockdown of ITSN-1s in ECs activated the mitochondrial pathway of apoptosis as determined by genomic DNA fragmentation, extensive mitochondrial fission, activation of the proapoptotic proteins BAK and BAX, and cytochrome c efflux from mitochondria. ITSN-1 knockdown acts as a proapoptotic signal that causes mitochondrial outer membrane permeabilization, dissipation of the mitochondrial membrane potential, and generation of reactive oxygen species. These effects were secondary to decreased activation of Erk1/2 and its direct activator MEK. Bcl-X(L) overexpression prevented BAX activation and the apoptotic ECs death induced by suppression of ITSN-1s. Our findings demonstrate a novel role of ITSN-1s as a negative regulator of the mitochondrial pathway-dependent apoptosis secondary to activation of the Erk1/2 survival signaling pathway.

    Funded by: NHLBI NIH HHS: P01 HL60678

    The Journal of biological chemistry 2007;282;23;17166-78

  • Computational model explains high activity and rapid cycling of Rho GTPases within protein complexes.

    Goryachev AB and Pokhilko AV

    Systems Biology Group, Bioinformatics Institute, Singapore, Singapore. Andrew.Goryachev@ed.ac.uk

    Formation of multiprotein complexes on cellular membranes is critically dependent on the cyclic activation of small GTPases. FRAP-based analyses demonstrate that within protein complexes, some small GTPases cycle nearly three orders of magnitude faster than they would spontaneously cycle in vitro. At the same time, experiments report concomitant excess of the activated, GTP-bound form of GTPases over their inactive form. Intuitively, high activity and rapid turnover are contradictory requirements. How the cells manage to maximize both remains poorly understood. Here, using GTPases of the Rab and Rho families as a prototype, we introduce a computational model of the GTPase cycle. We quantitatively investigate several plausible layouts of the cycling control module that consist of GEFs, GAPs, and GTPase effectors. We explain the existing experimental data and predict how the cycling of GTPases is controlled by the regulatory proteins in vivo. Our model explains distinct and separable roles that the activating GEFs and deactivating GAPs play in the GTPase cycling control. While the activity of GTPase is mainly defined by GEF, the turnover rate is a sole function of GAP. Maximization of the GTPase activity and turnover rate places conflicting requirements on the concentration of GAP. Therefore, to achieve a high activity and turnover rate at once, cells must carefully maintain concentrations of GEFs and GAPs within the optimal range. The values of these optimal concentrations indicate that efficient cycling can be achieved only within dense protein complexes typically assembled on the membrane surfaces. We show that the concentration requirement for GEF can be dramatically reduced by a GEF-activating GTPase effector that can also significantly boost the cycling efficiency. Interestingly, we find that the cycling regimes are only weakly dependent on the concentration of GTPase itself.

    PLoS computational biology 2006;2;12;e172

  • Global, in vivo, and site-specific phosphorylation dynamics in signaling networks.

    Olsen JV, Blagoev B, Gnad F, Macek B, Kumar C, Mortensen P and Mann M

    Center for Experimental BioInformatics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark.

    Cell signaling mechanisms often transmit information via posttranslational protein modifications, most importantly reversible protein phosphorylation. Here we develop and apply a general mass spectrometric technology for identification and quantitation of phosphorylation sites as a function of stimulus, time, and subcellular location. We have detected 6,600 phosphorylation sites on 2,244 proteins and have determined their temporal dynamics after stimulating HeLa cells with epidermal growth factor (EGF) and recorded them in the Phosida database. Fourteen percent of phosphorylation sites are modulated at least 2-fold by EGF, and these were classified by their temporal profiles. Surprisingly, a majority of proteins contain multiple phosphorylation sites showing different kinetics, suggesting that they serve as platforms for integrating signals. In addition to protein kinase cascades, the targets of reversible phosphorylation include ubiquitin ligases, guanine nucleotide exchange factors, and at least 46 different transcriptional regulators. The dynamic phosphoproteome provides a missing link in a global, integrative view of cellular regulation.

    Cell 2006;127;3;635-48

  • Alzheimer's disease and endocytic dysfunction: clues from the Down syndrome-related proteins, DSCR1 and ITSN1.

    Keating DJ, Chen C and Pritchard MA

    Prince Henry's Institute of Medical Research, Clayton, Vic., Australia.

    Down syndrome (DS) is a genetically-based disorder which results in multiple conditions for sufferers. Amongst these is a common early incidence of Alzheimer's disease (AD) which usually affects DS individuals by their mid 40s. This fact provides a clue that one or more of the genes located on chromosome 21 may be involved in the onset of AD. Current evidence suggests that endosomal disorders may underlie the earliest pathology of AD, preceding the classical pathological markers of beta-amyloid plaque deposition and neurofibrillary tangles. Therefore, any genes involved in endocytosis and vesicle trafficking which are over-expressed in DS are novel candidates in the pathogenesis of AD. Intersectin-1 (ITSN1) and Down syndrome candidate region 1 (DSCR1) are two such genes. Extensive in vitro data and data from Drosophila indicates that the over-expression of either of these genes or their products results in inhibition or ablation of endocytosis in neuronal as well as non-neuronal cells. This review discusses in detail the known and potential roles of ITSN1 and DSCR1 in DS, AD, endocytosis and vesicle trafficking.

    Ageing research reviews 2006;5;4;388-401

  • Intersectin regulates epidermal growth factor receptor endocytosis, ubiquitylation, and signaling.

    Martin NP, Mohney RP, Dunn S, Das M, Scappini E and O'Bryan JP

    Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA.

    Receptor tyrosine kinases (RTKs) are critical for normal cell growth, differentiation, and development, but they contribute to various pathological conditions when disrupted. Activation of RTKs stimulates a plethora of pathways, including the ubiquitylation and endocytosis of the receptor itself. Although endocytosis terminates RTK signaling, it has emerged as a requisite step in RTK activation of signaling pathways. We have discovered that the endocytic scaffolding protein intersectin (ITSN) cooperated with epidermal growth factor receptor (EGFR) in the regulation of cell growth and signaling. However, a biochemical link between ITSN and EGFR was not defined. In this study, we demonstrate that ITSN is a scaffold for the E3 ubiquitin ligase Cbl. ITSN forms a complex with Cbl in vivo mediated by the Src homology (SH) 3 domains binding to the Pro-rich COOH terminus of Cbl. This interaction stimulates the ubiquitylation and degradation of the activated EGFR. Furthermore, silencing ITSN by RNA interference attenuated EGFR internalization as well as activation of the extracellular signal-regulated kinasemitogen-activated protein kinase pathway, thereby demonstrating the importance of ITSN in EGFR function. Given the cooperativity between ITSN and additional RTKs, these results point to an important evolutionarily conserved, regulatory role for ITSN in RTK function that is necessary for both signaling from receptors as well as the ultimate termination of receptor signaling.

    Funded by: Intramural NIH HHS

    Molecular pharmacology 2006;70;5;1643-53

  • Role of the AP2 beta-appendage hub in recruiting partners for clathrin-coated vesicle assembly.

    Schmid EM, Ford MG, Burtey A, Praefcke GJ, Peak-Chew SY, Mills IG, Benmerah A and McMahon HT

    Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom.

    Adaptor protein complex 2 alpha and beta-appendage domains act as hubs for the assembly of accessory protein networks involved in clathrin-coated vesicle formation. We identify a large repertoire of beta-appendage interactors by mass spectrometry. These interact with two distinct ligand interaction sites on the beta-appendage (the "top" and "side" sites) that bind motifs distinct from those previously identified on the alpha-appendage. We solved the structure of the beta-appendage with a peptide from the accessory protein Eps15 bound to the side site and with a peptide from the accessory cargo adaptor beta-arrestin bound to the top site. We show that accessory proteins can bind simultaneously to multiple appendages, allowing these to cooperate in enhancing ligand avidities that appear to be irreversible in vitro. We now propose that clathrin, which interacts with the beta-appendage, achieves ligand displacement in vivo by self-polymerisation as the coated pit matures. This changes the interaction environment from liquid-phase, affinity-driven interactions, to interactions driven by solid-phase stability ("matricity"). Accessory proteins that interact solely with the appendages are thereby displaced to areas of the coated pit where clathrin has not yet polymerised. However, proteins such as beta-arrestin (non-visual arrestin) and autosomal recessive hypercholesterolemia protein, which have direct clathrin interactions, will remain in the coated pits with their interacting receptors.

    Funded by: Medical Research Council: G0100100, MC_U105178795

    PLoS biology 2006;4;9;e262

  • Intersectin-1L nucleotide exchange factor regulates secretory granule exocytosis by activating Cdc42.

    Malacombe M, Ceridono M, Calco V, Chasserot-Golaz S, McPherson PS, Bader MF and Gasman S

    Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique & Université Louis Pasteur, Strasbourg, France.

    Rho GTPases are key regulators of the actin cytoskeleton in membrane trafficking events. We previously reported that Cdc42 facilitates exocytosis in neuroendocrine cells by stimulating actin assembly at docking sites for secretory granules. These findings raise the question of the mechanism activating Cdc42 in exocytosis. The neuronal guanine nucleotide exchange factor, intersectin-1L, which specifically activates Cdc42 and is at an interface between membrane trafficking and actin dynamics, appears as an ideal candidate to fulfill this function. Using PC12 and chromaffin cells, we now show the presence of intersectin-1 at exocytotic sites. Moreover, through an RNA interference strategy coupled with expression of various constructs encoding the guanine nucleotide exchange domain, we demonstrate that intersectin-1L is an essential component of the exocytotic machinery. Silencing of intersectin-1 prevents secretagogue-induced activation of Cdc42 revealing intersectin-1L as the factor integrating Cdc42 activation to the exocytotic pathway. Our results extend the current role of intersectin-1L in endocytosis to a function in exocytosis and support the idea that intersectin-1L is an adaptor that coordinates exo-endocytotic membrane trafficking in secretory cells.

    The EMBO journal 2006;25;15;3494-503

  • Two mechanistically distinct forms of endocytosis in adrenal chromaffin cells: Differential effects of SH3 domains and amphiphysin antagonism.

    Elhamdani A, Azizi F, Solomaha E, Palfrey HC and Artalejo CR

    Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA. aelhamda@med.wayne.edu

    We previously identified two forms of endocytosis using capacitance measurements in chromaffin cells: rapid endocytosis (RE), dynamin-1 dependent but clathrin-independent and slow endocytosis (SE), dynamin-2 and clathrin-dependent. Various recombinant SH3 domains that interact with the proline-rich domain of dynamin were introduced into single cells via the patch pipette. GST-SH3 domains of amphiphysin-1, intersectin-IC, and endophilin-I inhibited SE but had no effect on RE. Grb2-SH3 (N-terminal) or a mutant of amphiphysin-1-SH3 was inactive on either process. These data confirm that dynamin-1 dependent RE is independent of clathrin and show that amphiphysin is exclusively associated with clathrin and dynamin-2-dependent SE.

    Funded by: NIDDK NIH HHS: DK-58921; NIGMS NIH HHS: GM-56396; NIMH NIH HHS: MH-47181

    FEBS letters 2006;580;13;3263-9

  • A human protein-protein interaction network: a resource for annotating the proteome.

    Stelzl U, Worm U, Lalowski M, Haenig C, Brembeck FH, Goehler H, Stroedicke M, Zenkner M, Schoenherr A, Koeppen S, Timm J, Mintzlaff S, Abraham C, Bock N, Kietzmann S, Goedde A, Toksöz E, Droege A, Krobitsch S, Korn B, Birchmeier W, Lehrach H and Wanker EE

    Max Delbrueck Center for Molecular Medicine, 13092 Berlin-Buch, Germany.

    Protein-protein interaction maps provide a valuable framework for a better understanding of the functional organization of the proteome. To detect interacting pairs of human proteins systematically, a protein matrix of 4456 baits and 5632 preys was screened by automated yeast two-hybrid (Y2H) interaction mating. We identified 3186 mostly novel interactions among 1705 proteins, resulting in a large, highly connected network. Independent pull-down and co-immunoprecipitation assays validated the overall quality of the Y2H interactions. Using topological and GO criteria, a scoring system was developed to define 911 high-confidence interactions among 401 proteins. Furthermore, the network was searched for interactions linking uncharacterized gene products and human disease proteins to regulatory cellular pathways. Two novel Axin-1 interactions were validated experimentally, characterizing ANP32A and CRMP1 as modulators of Wnt signaling. Systematic human protein interaction screens can lead to a more comprehensive understanding of protein function and cellular processes.

    Cell 2005;122;6;957-68

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

    Wang JB, Wu WJ and Cerione RA

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

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

    Funded by: NIGMS NIH HHS: GM47458

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

  • Kinetics of Src homology 3 domain association with the proline-rich domain of dynamins: specificity, occlusion, and the effects of phosphorylation.

    Solomaha E, Szeto FL, Yousef MA and Palfrey HC

    Department of Neurobiology, Pharamacology, and Physiology, University of Chicago, IL 60637, USA.

    Dynamin function is mediated in part through association of its proline-rich domain (PRD) with the Src homology 3 (SH3) domains of several putative binding proteins. To assess the specificity and kinetics of this process, we undertook surface plasmon resonance studies of the interaction between isolated PRDs of dynamin-1 and -2 and several purified SH3 domains. Glutathione S-transferase-linked SH3 domains bound with high affinity (K(D) approximately 10 nm to 1 microm) to both dynamin-1 and -2. The simplest interaction appeared to take place with the amphiphysin-SH3 domain; this bound to a single high affinity site (K(D) approximately 10 nm) in the C terminus of dynamin-1 PRD, as predicted by previous studies. Binding to the dynamin-2 PRD was also monophasic but with a slightly lower affinity (K(D) approximately 25 nm). Endophilin-SH3 binding to both dynamin-1 and -2 PRDs was biphasic, with one high affinity site (K(D) approximately 14 nm) in the N terminus of the PRD and another lower affinity site (K(D) approximately 60 nm) in the C terminus of dynamin-1. The N-terminal site in dynamin-2 PRD had a 10-fold lower affinity for endophilin-SH3. Preloading of dynamin-1 PRD with the amphiphysin-SH3 domain partially occluded binding of the endophilin-SH3 domain, indicating overlap between the binding sites in the C terminus, but endophilin was still able to interact with the high affinity N-terminal site. This shows that more than one SH3 domain can simultaneously bind to the PRD and suggests that competition probably occurs in vivo between different SH3-containing proteins for the limited number of PXXP motifs. Endophilin-SH3 binding to the high affinity site was disrupted when dynamin-1 PRD was phosphorylated with Cdk5, indicating that this site overlaps the phosphorylation sites, but amphiphysin-SH3 binding was unaffected. Other SH3 domains showed similarly complex binding characteristics, and substantial differences were noted between the PRDs from dynamin-1 and -2. For example, SH3 domains from c-Src, Grb2, and intersectin bound only to the C-terminal half of dynamin-2 PRD but to both the N- and C-terminal portions of dynamin-1 PRD. Thus, differential binding of SH3 domain-containing proteins to dynamin-1 and -2 may contribute to the distinct functions performed by these isoforms.

    The Journal of biological chemistry 2005;280;24;23147-56

  • Expression of AMAP1, an ArfGAP, provides novel targets to inhibit breast cancer invasive activities.

    Onodera Y, Hashimoto S, Hashimoto A, Morishige M, Mazaki Y, Yamada A, Ogawa E, Adachi M, Sakurai T, Manabe T, Wada H, Matsuura N and Sabe H

    Department of Molecular Biology, Osaka Bioscience Institute, Suita, Osaka, Japan.

    Identification of the molecular machinery employed in cancer invasion, but not in normal adult cells, will greatly contribute to cancer therapeutics. Here we found that an ArfGAP, AMAP1/PAG2, is expressed at high levels in highly invasive breast cancer cells, but at very low levels in noninvasive breast cancer cells and normal mammary epithelial cells. siRNA-mediated silencing of AMAP1 effectively blocked the invasive activities. AMAP1 expression in human breast primary tumors also indicated its potential correlation with malignancy. Paxillin and cortactin have been shown to colocalize at invadopodia and play a pivotal role in breast cancer invasion. We found that AMAP1 is also localized at invadopodia, and acts to bridge paxillin and cortactin. This AMAP1-mediated trimeric protein complex was detected only in invasive cancer cells, and blocking this complex formation effectively inhibited their invasive activities in vitro and metastasis in mice. Our results indicate that AMAP1 is a component involved in invasive activities of different breast cancers, and provide new information regarding the possible therapeutic targets for prevention of breast cancer invasion and metastasis.

    The EMBO journal 2005;24;5;963-73

  • Large-scale characterization of HeLa cell nuclear phosphoproteins.

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

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

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

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

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

  • Tal, a Tsg101-specific E3 ubiquitin ligase, regulates receptor endocytosis and retrovirus budding.

    Amit I, Yakir L, Katz M, Zwang Y, Marmor MD, Citri A, Shtiegman K, Alroy I, Tuvia S, Reiss Y, Roubini E, Cohen M, Wides R, Bacharach E, Schubert U and Yarden Y

    Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.

    The tumor suppressor gene 101 (tsg101) regulates vesicular trafficking processes in yeast and mammals. We report a novel protein, Tal (Tsg101-associated ligase), whose RING finger is necessary for multiple monoubiquitylation of Tsg101. Bivalent binding of Tsg101 to a tandem tetrapeptide motif (PTAP) and to a central region of Tal is essential for Tal-mediated ubiquitylation of Tsg101. By studying endocytosis of the epidermal growth factor receptor and egress of the human immunodeficiency virus, we conclude that Tal regulates a Tsg101-associated complex responsible for the sorting of cargo into cytoplasm-containing vesicles that bud at the multivesicular body and at the plasma membrane.

    Genes & development 2004;18;14;1737-52

  • Alternative splicing of mammalian Intersectin 1: domain associations and tissue specificities.

    Tsyba L, Skrypkina I, Rynditch A, Nikolaienko O, Ferenets G, Fortna A and Gardiner K

    Institute of Molecular Biology and Genetics, 150 Zabolotnogo, Kyiv 03143, Ukraine.

    The Intersectin 1 (ITSN1) protein functions in clathrin-mediated endocytosis and in MAP kinase signaling. The complex domain structure comprises two EH and five SH3 domains in the short isoform, plus RhoGEF, pleckstrin, and putative calcium-interaction domains in the long isoform. Alternative splicing of exon 20, affecting the SH3A domain, has been shown in rat and that of exons 25 + 26, affecting the SH3C domain, has been shown in human and rat. Here we report 7 novel splice variants of the human and mouse ITSN1 genes and demonstrate conservation of alternative splicing affecting SH3A and SH3C in mouse. The novel variants encode transcripts with altered EH domain spacing and RhoGEF domain structure and possible targets of nonsense-mediated decay. Eight and 16 protein variants of the short and long ITSN1 isoforms, respectively, are predicted. These isoforms likely serve to modulate the many complex protein interactions and functions of ITSN1.

    Genomics 2004;84;1;106-13

  • Functional proteomics mapping of a human signaling pathway.

    Colland F, Jacq X, Trouplin V, Mougin C, Groizeleau C, Hamburger A, Meil A, Wojcik J, Legrain P and Gauthier JM

    Hybrigenics SA, 75014 Paris, France. fcolland@hybrigenics.fr

    Access to the human genome facilitates extensive functional proteomics studies. Here, we present an integrated approach combining large-scale protein interaction mapping, exploration of the interaction network, and cellular functional assays performed on newly identified proteins involved in a human signaling pathway. As a proof of principle, we studied the Smad signaling system, which is regulated by members of the transforming growth factor beta (TGFbeta) superfamily. We used two-hybrid screening to map Smad signaling protein-protein interactions and to establish a network of 755 interactions, involving 591 proteins, 179 of which were poorly or not annotated. The exploration of such complex interaction databases is improved by the use of PIMRider, a dedicated navigation tool accessible through the Web. The biological meaning of this network is illustrated by the presence of 18 known Smad-associated proteins. Functional assays performed in mammalian cells including siRNA knock-down experiments identified eight novel proteins involved in Smad signaling, thus validating this integrated functional proteomics approach.

    Genome research 2004;14;7;1324-32

  • 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

  • Intersectin regulates fission and internalization of caveolae in endothelial cells.

    Predescu SA, Predescu DN, Timblin BK, Stan RV and Malik AB

    Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.

    Intersectin, a multiple Eps15 homology and Src homology 3 (SH3) domain-containing protein, is a component of the endocytic machinery in neurons and nonneuronal cells. However, its role in endocytosis via caveolae in endothelial cells (ECs) is unclear. We demonstrate herein by coimmunoprecipitation, velocity sedimentation on glycerol gradients, and cross-linking that intersectin is present in ECs in a membrane-associated protein complex containing dynamin and SNAP-23. Electron microscopy (EM) immunogold labeling studies indicated that intersectin associated preferentially with the caveolar necks, and it remained associated with caveolae after their fission from the plasmalemma. A cell-free system depleted of intersectin failed to support caveolae fission from the plasma membrane. A biotin assay used to quantify caveolae internalization and extensive EM morphological analysis of ECs overexpressing wt-intersectin indicated a wide range of morphological changes (i.e., large caveolae clusters marginated at cell periphery and pleiomorphic caveolar necks) as well as impaired caveolae internalization. Biochemical evaluation of caveolae-mediated uptake by ELISA showed a 68.4% inhibition by reference to control. We also showed that intersectin interaction with dynamin was important in regulating the fission and internalization of caveolae. Taken together, the results indicate the crucial role of intersectin in the mechanism of caveolae fission in endothelial cells.

    Funded by: NHLBI NIH HHS: HL 17080, P01 HL060678, P01 HL60678, R01 HL065418, R01 HL065418-01A1, R01 HL065418-02, R01 HL065418-03

    Molecular biology of the cell 2003;14;12;4997-5010

  • Intersectin activates Ras but stimulates transcription through an independent pathway involving JNK.

    Mohney RP, Das M, Bivona TG, Hanes R, Adams AG, Philips MR and O'Bryan JP

    Laboratory of Signal Transduction, National Institute of Environmental Health Services, NIH/DHHS, Building 101, Research Triangle Park, NC 27709, USA.

    Intersectin (ITSN) is a molecular scaffold involved in regulating endocytosis and mitogenic signaling. We previously demonstrated that ITSN transformed rodent fibroblasts, accelerated hormone-induced maturation of Xenopus oocytes, and activated the Elk-1 transcription factor through an MEK- and Erk-independent mechanism. We now demonstrate that ITSN complexes with the Ras guanine nucleotide exchange factor Sos1 leading to increased RasGTP levels. Using fluorescence resonant energy transfer analysis, we demonstrate that ITSN complexes with Ras in living cells leading to Ras activation on intracellular vesicles. These vesicles contain epidermal growth factor receptor but are distinct from transferrin-positive vesicles. However, Ras is not required for ITSN stimulation of transcription. Rather, we demonstrate that ITSN signals through JNK to activate Elk-1. Although ITSN activation of Elk-1 was Ras-independent, ITSN cooperates with Ras to synergistically activate JNK. These findings indicate that ITSN activates multiple intracellular signaling pathways and suggest that this adaptor protein may coordinately regulate the activity of these pathways in vivo.

    The Journal of biological chemistry 2003;278;47;47038-45

  • DISC1 (Disrupted-In-Schizophrenia 1) is a centrosome-associated protein that interacts with MAP1A, MIPT3, ATF4/5 and NUDEL: regulation and loss of interaction with mutation.

    Morris JA, Kandpal G, Ma L and Austin CP

    Department of Neuroscience, Merck Research Laboratories, West Point, PA 19486, USA.

    Disrupted-In-Schizophrenia 1 (DISC1) is a novel gene associated with schizophrenia by multiple genetic studies. In order to determine how mutations in DISC1 might cause susceptibility to schizophrenia, we undertook a comprehensive study of the cellular biology of DISC1 in its full-length and disease-associated mutant forms. DISC1 interacts by yeast two-hybrid, mammalian two-hybrid, and co-immunoprecipitation assays with multiple proteins of the centrosome and cytoskeletal system, including MIPT3, MAP1A and NUDEL; proteins which localize receptors to membranes, including alpha-actinin2 and beta4-spectrin; and proteins which transduce signals from membrane receptors, including ATF4 and ATF5. Truncated mutant DISC1 fails to interact with ATF4, ATF5 or NUDEL. Deletion mapping demonstrated that DISC1 has distinct interaction domains: MAP1A interacts via its LC2 domain with the N-terminus of DISC1, whereas MIPT3 and NUDEL bind via their C-terminal domains to the central coiled-coil domain of DISC1, and ATF4/5 bind via their C-terminal domains to the C-terminus of DISC1. In its full-length form, DISC1 protein localizes to predominantly perinuclear punctate structures which extend into neurites in some cells; mutant truncated DISC1, by contrast, is seen in a diffuse pattern throughout the cytoplasm and abundantly in neurites. Both forms co-localize with the centrosomal complex, although truncated less abundantly than full-length DISC1. Although both full-length and mutant DISC1 are found in microtubule fractions, neither form of DISC1 appears to bind directly to microtubules, but rather do so in a MIPT3-dependent fashion that is stabilized by taxol. Based on these data, we propose that DISC1 is a multifunctional protein whose truncation contributes to schizophrenia susceptibility by disrupting intracellular transport, neurite architecture and/or neuronal migration, all of which have been hypothesized to be pathogenic in the schizophrenic brain.

    Human molecular genetics 2003;12;13;1591-608

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

    Rabizadeh S and Bredesen DE

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

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

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

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

    Salehi AH, Xanthoudakis S and Barker PA

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

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

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

  • EphB receptors regulate dendritic spine development via intersectin, Cdc42 and N-WASP.

    Irie F and Yamaguchi Y

    The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA.

    Funded by: NICHD NIH HHS: HD25938

    Nature neuroscience 2002;5;11;1117-8

  • Structural basis for the selective activation of Rho GTPases by Dbl exchange factors.

    Snyder JT, Worthylake DK, Rossman KL, Betts L, Pruitt WM, Siderovski DP, Der CJ and Sondek J

    Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, Chapel Hill, North Carolina 27599, USA.

    Activation of Rho-family GTPases involves the removal of bound GDP and the subsequent loading of GTP, all catalyzed by guanine nucleotide exchange factors (GEFs) of the Dbl-family. Despite high sequence conservation among Rho GTPases, Dbl proteins possess a wide spectrum of discriminatory potentials for Rho-family members. To rationalize this specificity, we have determined crystal structures of the conserved, catalytic fragments (Dbl and pleckstrin homology domains) of the exchange factors intersectin and Dbs in complex with their cognate GTPases, Cdc42 and RhoA, respectively. Structure-based mutagenesis of intersectin and Dbs reveals the key determinants responsible for promoting exchange activity in Cdc42, Rac1 and RhoA. These findings provide critical insight into the structural features necessary for the proper pairing of Dbl-exchange factors with Rho GTPases and now allow for the detailed manipulation of signaling pathways mediated by these oncoproteins in vivo.

    Nature structural biology 2002;9;6;468-75

  • The activity of the GTPase-activating protein CdGAP is regulated by the endocytic protein intersectin.

    Jenna S, Hussain NK, Danek EI, Triki I, Wasiak S, McPherson PS and Lamarche-Vane N

    Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 2B2, Canada.

    The Rho GTPases RhoA, Rac1, and Cdc42 play a major role in regulating the reorganization of the actin cytoskeleton. We recently identified CdGAP, a novel GTPase-activating protein with activity toward Rac1 and Cdc42. CdGAP consists of a N-terminal GAP domain, a central domain, and a C-terminal proline-rich domain. Here we show that through a subset of its Src homology 3 domains, the endocytic protein intersectin interacts with CdGAP. In platelet-derived growth factor-stimulated Swiss 3T3 cells, intersectin co-localizes with CdGAP and inhibits its GAP activity toward Rac1. Intersectin-Src homology 3 also inhibits CdGAP activity in GAP assays in vitro. Although the C-terminal proline-rich domain of CdGAP is required for the regulation of its GAP activity by intersectin both in vivo and in vitro, it is not necessary for CdGAP-intersectin interaction. Our data suggest that the central domain of CdGAP is required for CdGAP-intersectin interaction. Thus, we propose a model in which intersectin binding results in a change of CdGAP conformation involving the proline-rich domain that leads to the inhibition of its GAP activity. These observations provide the first demonstration of a direct regulation of RhoGAP activity through a protein-protein interaction and suggest a function for intersectin in Rac1 regulation and actin dynamics.

    The Journal of biological chemistry 2002;277;8;6366-73

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

    Harrington AW, Kim JY and Yoon SO

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

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

    Funded by: NINDS NIH HHS: R01 NS39472-01

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

  • The human intersectin genes and their spliced variants are differentially expressed.

    Pucharcos C, Casas C, Nadal M, Estivill X and de la Luna S

    Down Syndrome Research Group, Medical and Molecular Genetics Center-IRO, Gran Via s/n Km 2.7, L'Hospitalet de Llobregat, 08907, Barcelona, Spain.

    Human intersectins (ITSN1 and ITSN2) are members of a conserved family of proteins involved in clathrin-mediated endocytosis. A short and a long isoform with different protein domain compositions have been described for both human intersectins. Here, we have resolved the exon/intron structure of the ITSN2 gene to explain the genomic origin of its alternatively spliced transcripts. Comparison of the two ITSN human genes shows a high level of conservation in their genomic organization, including the main alternative splicing events. An extensive tissue expression analysis of the two predominant transcripts as well as other minor variants shows that ITSN expression is under tissue and developmental controls. Their differential expression is made more evident when the expression of both intersectins is studied by in situ hybridization in mouse brain.

    Biochimica et biophysica acta 2001;1521;1-3;1-11

  • Endocytic protein intersectin-l regulates actin assembly via Cdc42 and N-WASP.

    Hussain NK, Jenna S, Glogauer M, Quinn CC, Wasiak S, Guipponi M, Antonarakis SE, Kay BK, Stossel TP, Lamarche-Vane N and McPherson PS

    Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada.

    Intersectin-s is a modular scaffolding protein regulating the formation of clathrin-coated vesicles. In addition to the Eps15 homology (EH) and Src homology 3 (SH3) domains of intersectin-s, the neuronal variant (intersectin-l) also has Dbl homology (DH), pleckstrin homology (PH) and C2 domains. We now show that intersectin-l functions through its DH domain as a guanine nucleotide exchange factor (GEF) for Cdc42. In cultured cells, expression of DH-domain-containing constructs cause actin rearrangements specific for Cdc42 activation. Moreover, in vivo studies reveal that stimulation of Cdc42 by intersectin-l accelerates actin assembly via N-WASP and the Arp2/3 complex. N-WASP binds directly to intersectin-l and upregulates its GEF activity, thereby generating GTP-bound Cdc42, a critical activator of N-WASP. These studies reveal a role for intersectin-l in a novel mechanism of N-WASP activation and in regulation of the actin cytoskeleton.

    Nature cell biology 2001;3;10;927-32

  • Stonin 2: an adaptor-like protein that interacts with components of the endocytic machinery.

    Martina JA, Bonangelino CJ, Aguilar RC and Bonifacino JS

    Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.

    Endocytosis of cell surface proteins is mediated by a complex molecular machinery that assembles on the inner surface of the plasma membrane. Here, we report the identification of two ubiquitously expressed human proteins, stonin 1 and stonin 2, related to components of the endocytic machinery. The human stonins are homologous to the Drosophila melanogaster stoned B protein and exhibit a modular structure consisting of an NH(2)-terminal proline-rich domain, a central region of homology specific to the stonins, and a COOH-terminal region homologous to the mu subunits of adaptor protein (AP) complexes. Stonin 2, but not stonin 1, interacts with the endocytic machinery proteins Eps15, Eps15R, and intersectin 1. These interactions occur via two NPF motifs in the proline-rich domain of stonin 2 and Eps15 homology domains of Eps15, Eps15R, and intersectin 1. Stonin 2 also interacts indirectly with the adaptor protein complex, AP-2. In addition, stonin 2 binds to the C2B domains of synaptotagmins I and II. Overexpression of GFP-stonin 2 interferes with recruitment of AP-2 to the plasma membrane and impairs internalization of the transferrin, epidermal growth factor, and low density lipoprotein receptors. These observations suggest that stonin 2 is a novel component of the general endocytic machinery.

    The Journal of cell biology 2001;153;5;1111-20

  • Intersectin 2, a new multimodular protein involved in clathrin-mediated endocytosis.

    Pucharcos C, Estivill X and de la Luna S

    Down Syndrome Research Group, Medical and Molecular Genetics Center, IRO, Hospital Duran i Reynals, Avia. de Castelldefels Km 2.7, L'Hospitalet de Llobregat, 08907, Barcelona, Spain.

    Intersectin 1 (ITSN1) is a binding partner of dynamin that has been shown to participate in clathrin-mediated endocytosis. Here we report the characterization of a new human gene, ITSN2, highly similar to ITSN1. Alternative splicing of ITSN2 generates a short isoform with two EH domains, a coiled-coil region and five SH3 domains, and a longer isoform containing extra carboxy domains (DH, PH and C2 domains), suggesting that it could act as a guanine nucleotide exchange factor for Rho-like GTPases. ITSN2 expression analysis indicates that it is widely expressed in human tissues. Intersectin 2 isoforms show a subcellular distribution similar to other components of the endocytic machinery and co-localize with Eps15. Moreover, their overexpression, as well as the corresponding ITSN1 protein forms, inhibits transferrin internalization.

    FEBS letters 2000;478;1-2;43-51

  • The DNA sequence of human chromosome 21.

    Hattori M, Fujiyama A, Taylor TD, Watanabe H, Yada T, Park HS, Toyoda A, Ishii K, Totoki Y, Choi DK, Groner Y, Soeda E, Ohki M, Takagi T, Sakaki Y, Taudien S, Blechschmidt K, Polley A, Menzel U, Delabar J, Kumpf K, Lehmann R, Patterson D, Reichwald K, Rump A, Schillhabel M, Schudy A, Zimmermann W, Rosenthal A, Kudoh J, Schibuya K, Kawasaki K, Asakawa S, Shintani A, Sasaki T, Nagamine K, Mitsuyama S, Antonarakis SE, Minoshima S, Shimizu N, Nordsiek G, Hornischer K, Brant P, Scharfe M, Schon O, Desario A, Reichelt J, Kauer G, Blocker H, Ramser J, Beck A, Klages S, Hennig S, Riesselmann L, Dagand E, Haaf T, Wehrmeyer S, Borzym K, Gardiner K, Nizetic D, Francis F, Lehrach H, Reinhardt R, Yaspo ML and Chromosome 21 mapping and sequencing consortium

    RIKEN, Genomic Sciences Center, Sagamihara, Japan.

    Chromosome 21 is the smallest human autosome. An extra copy of chromosome 21 causes Down syndrome, the most frequent genetic cause of significant mental retardation, which affects up to 1 in 700 live births. Several anonymous loci for monogenic disorders and predispositions for common complex disorders have also been mapped to this chromosome, and loss of heterozygosity has been observed in regions associated with solid tumours. Here we report the sequence and gene catalogue of the long arm of chromosome 21. We have sequenced 33,546,361 base pairs (bp) of DNA with very high accuracy, the largest contig being 25,491,867 bp. Only three small clone gaps and seven sequencing gaps remain, comprising about 100 kilobases. Thus, we achieved 99.7% coverage of 21q. We also sequenced 281,116 bp from the short arm. The structural features identified include duplications that are probably involved in chromosomal abnormalities and repeat structures in the telomeric and pericentromeric regions. Analysis of the chromosome revealed 127 known genes, 98 predicted genes and 59 pseudogenes.

    Nature 2000;405;6784;311-9

  • SCAMP1 function in endocytosis.

    Fernández-Chacón R, Achiriloaie M, Janz R, Albanesi JP and Südhof TC

    Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.

    Secretory carrier membrane proteins (SCAMPs) are ubiquitous components of recycling vesicles that shuttle between the plasma membrane, endosomes, and the trans-Golgi complex. SCAMPs contain multiple N-terminal NPF repeats and four highly conserved transmembrane regions. NPF repeats often interact with EH domain proteins that function in budding of transport vesicles from the plasma membrane or the Golgi complex. We now show that the NPF repeats of SCAMP1 bind to two EH domain proteins, intersectin 1, which is involved in endocytic budding at the plasma membrane, and gamma-synergin, which may mediate the budding of vesicles in the trans-Golgi complex. Expression of SCAMP1 lacking the N-terminal NPF repeats potently inhibited transferrin uptake by endocytosis. Our data suggest that one of the functions of SCAMPs is to participate in endocytosis via a mechanism which may involve the recruitment of clathrin coats to the plasma membrane and the trans-Golgi network.

    Funded by: NIGMS NIH HHS: R01-GM55562

    The Journal of biological chemistry 2000;275;17;12752-6

  • The endocytic protein intersectin is a major binding partner for the Ras exchange factor mSos1 in rat brain.

    Tong XK, Hussain NK, de Heuvel E, Kurakin A, Abi-Jaoude E, Quinn CC, Olson MF, Marais R, Baranes D, Kay BK and McPherson PS

    Department of Neurology, Montreal Neurological Institute, Montreal, QC H3A 2B4, Canada.

    We recently identified intersectin, a protein containing two EH and five SH3 domains, as a component of the endocytic machinery. The N-terminal SH3 domain (SH3A), unlike other SH3 domains from intersectin or various endocytic proteins, specifically inhibits intermediate events leading to the formation of clathrin-coated pits. We have now identified a brain-enriched, 170 kDa protein (p170) that interacts specifically with SH3A. Screening of combinatorial peptides reveals the optimal ligand for SH3A as Pp(V/I)PPR, and the 170 kDa mammalian son-of-sevenless (mSos1) protein, a guanine-nucleotide exchange factor for Ras, con- tains two copies of the matching sequence, PPVPPR. Immunodepletion studies confirm that p170 is mSos1. Intersectin and mSos1 are co-enriched in nerve terminals and are co-immunoprecipitated from brain extracts. SH3A competes with the SH3 domains of Grb2 in binding to mSos1, and the intersectin-mSos1 complex can be separated from Grb2 by sucrose gradient centrifugation. Overexpression of the SH3 domains of intersectin blocks epidermal growth factor-mediated Ras activation. These results suggest that intersectin functions in cell signaling in addition to its role in endocytosis and may link these cellular processes.

    Funded by: NINDS NIH HHS: NS22807

    The EMBO journal 2000;19;6;1263-71

  • Alu-splice cloning of human Intersectin (ITSN), a putative multivalent binding protein expressed in proliferating and differentiating neurons and overexpressed in Down syndrome.

    Pucharcós C, Fuentes JJ, Casas C, de la Luna S, Alcántara S, Arbonés ML, Soriano E, Estivill X and Pritchard M

    Down Syndrome Research Group, Medical and Molecular Genetics Center, IRO, Hospital Duran i Reynals, Barcelona, Spain.

    By Alu-splice PCR we have trapped two exons and subsequently identified the full length cDNA of a human gene, Intersectin (ITSN), which maps to chromosome 21q22.1 between markers D21S320 and D21S325. The gene has the potential to code for at least two different protein isoforms by alternative splicing (ITSN-L and ITSN-S). Intersectin exists with a high degree of similarity in flies, frogs and mammals, suggesting a conserved role in higher eukaryotes. Analysis of the expression pattern of human and mouse Intersectin detected mRNAs in all adult and foetal tissues tested, with the longer isoform present in brain. In situ hybridisation studies in the developing mouse brain showed ITSN expression in both proliferating and differentiating neurons. The genomic structure of ITSN was determined using the chromosome 21 sequences deposited in the public databases. The protein contains several known motifs which implicate ITSN in clathrin mediated endocytosis and synaptic vesicle recycling. The expression pattern of Intersectin in mouse brain, its presumed function and its overexpression in brains from Down syndrome patients, suggest that Intersectin may contribute in a gene dosage-dependent manner to some of the abnormalities of Down syndrome.

    European journal of human genetics : EJHG 1999;7;6;704-12

  • EHSH1/intersectin, a protein that contains EH and SH3 domains and binds to dynamin and SNAP-25. A protein connection between exocytosis and endocytosis?

    Okamoto M, Schoch S and Südhof TC

    Center for Basic Neuroscience, Howard Hughes Medical Institute, and the Department of Molecular Genetics, The University of Texas Southwestern Medical School, Dallas Texas 75235, USA.

    In yeast two-hybrid screens for proteins that bind to SNAP-25 and may be involved in exocytosis, we isolated a protein called EHSH1 (for EH domain/SH3 domain-containing protein). Cloning of full-length cDNAs revealed that EHSH1 is composed of an N-terminal region with two EH domains, a central region that is enriched in lysine, leucine, glutamate, arginine, and glutamine (KLERQ domain), and a C-terminal region comprised of five SH3 domains. The third SH3 domain is alternatively spliced. Data bank searches demonstrated that EHSH1 is very similar to Xenopus and human intersectins and to human SH3P17. In addition, we identified expressed sequence tags that encode a second isoform of EHSH1, called EHSH2. EHSH1 is abundantly expressed in brain and at lower levels in all other tissues tested. In binding studies, we found that the central KLERQ domain of EHSH1 binds to recombinant or native brain SNAP-25 and SNAP-23. The C-terminal SH3 domains, by contrast, quantitatively interact with dynamin, a protein involved in endocytosis. Dynamin strongly binds to the alternatively spliced central SH3 domain (SH3C) and the two C-terminal SH3 domains (SH3D and SH3E) but not to the N-terminal SH3 domains (SH3A and SH3B). Immunoprecipitations confirmed that both dynamin and SNAP-25 are complexed to EHSH1 in brain. Our data suggest that EHSH1/intersectin may be a novel adaptor protein that couples endocytic membrane traffic to exocytosis. The ability of multiple SH3 domains in EHSH1 to bind to dynamin suggests that EHSH1 can cluster several dynamin molecules in a manner that is regulated by alternative splicing.

    The Journal of biological chemistry 1999;274;26;18446-54

  • The EH and SH3 domain Ese proteins regulate endocytosis by linking to dynamin and Eps15.

    Sengar AS, Wang W, Bishay J, Cohen S and Egan SE

    Programs of Cancer and Blood Research, and Developmental Biology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada. segan@sickkids.on.ca

    Clathrin-mediated endocytosis is a multistep process which requires interaction between a number of conserved proteins. We have cloned two mammalian genes which code for a number of endocytic adaptor proteins. Two of these proteins, termed Ese1 and Ese2, contain two N-terminal EH domains, a central coiled-coil domain and five C-terminal SH3 domains. Ese1 is constitutively associated with Eps15 proteins to form a complex with at least 14 protein-protein interaction surfaces. Yeast two-hybrid assays have revealed that Ese1 EH and SH3 domains bind epsin family proteins and dynamin, respectively. Overexpression of Ese1 is sufficient to block clathrin-mediated endocytosis in cultured cells, presumably through disruption of higher order protein complexes, which are assembled on the endogenous Ese1-Eps15 scaffold. The Ese1-Eps15 scaffold therefore links dynamin, epsin and other endocytic pathway components.

    The EMBO journal 1999;18;5;1159-71

  • Intersectin, a novel adaptor protein with two Eps15 homology and five Src homology 3 domains.

    Yamabhai M, Hoffman NG, Hardison NL, McPherson PS, Castagnoli L, Cesareni G and Kay BK

    Department of Pharmacology, University of Wisconsin, Madison, Wisconsin 53706-1532, USA.

    We screened a Xenopus laevis oocyte cDNA expression library with a Src homology 3 (SH3) class II peptide ligand and identified a 1270-amino acid-long protein containing two Eps15 homology (EH) domains, a central coiled-coil region, and five SH3 domains. We named this protein Intersectin, because it potentially brings together EH and SH3 domain-binding proteins into a macromolecular complex. The ligand preference of the EH domains were deduced to be asparajine-proline-phenylalanine (NPF) or cyclized NPF (CX1-2NPFXXC), depending on the type of phage-displayed combinatorial peptide library used. Screens of a mouse embryo cDNA library with the EH domains of Intersectin yielded clones for the Rev-associated binding/Rev-interacting protein (RAB/Rip) and two novel proteins, which we named Intersectin-binding proteins (Ibps) 1 and 2. All three proteins contain internal and C-terminal NPF peptide sequences, and Ibp1 and Ibp2 also contain putative clathrin-binding sites. Deletion of the C-terminal sequence, NPFL-COOH, from RAB/Rip eliminated EH domain binding, whereas fusion of the same peptide sequence to glutathione S-transferase generated strong binding to the EH domains of Intersectin. Several experiments support the conclusion that the free carboxylate group contributes to binding of the NPFL motif at the C terminus of RAB/Rip to the EH domains of Intersectin. Finally, affinity selection experiments with the SH3 domains of Intersectin identified two endocytic proteins, dynamin and synaptojanin, as potential interacting proteins. We propose that Intersectin is a component of the endocytic machinery.

    The Journal of biological chemistry 1998;273;47;31401-7

  • Two isoforms of a human intersectin (ITSN) protein are produced by brain-specific alternative splicing in a stop codon.

    Guipponi M, Scott HS, Chen H, Schebesta A, Rossier C and Antonarakis SE

    Department of Genetics and Microbiology, University of Geneva Medical School, Geneva 4, 1211.

    Using selected trapped exons with homology to specific protein domains, we identified a new full-length cDNA encoding a protein containing many motifs for protein-protein interactions. There are two major mRNA transcripts, a ubiquitously expressed mRNA of 5.3 kb and a brain-specific transcript of approximately 15 kb, encoding proteins of 1220 and 1721 amino acids, respectively. The stop codon of the ORF of the shorter transcript is split between adjacent exons. In brain tissues the last exon of the short transcript is skipped, and an alternative downstream exon, the first of several additional, is used to produce the 15-kb mRNA. The putative human protein is highly homologous to Xenopus intersectin (81% identical) and to Drosophila dynamin-associated protein, Dap160 (31% identical) and was termed intersectin (ITSN). Both human proteins contain five SH3 (Src homology 3) domains, two EH (Eps15 homology) domains, and an alpha-helix-forming region. The brain-specific long transcript encodes for three additional domains: a GEF (guanine-nucleotide exchange factors), a PH (pleckstrin homology), and a C2 domain. The Drosophila homologue is associated with dynamin, a protein family involved in the endocytic pathway and/or synaptic vesicle recycling. The structure of the human ITSN protein is consistent with its involvement in membrane-associated molecular trafficking and signal transduction pathways. The human ITSN gene has been mapped to 21q22. 1-q22.2 between markers D21S319 and D21S65, and its importance in Down syndrome and monogenic disorders is currently unknown.

    Genomics 1998;53;3;369-76

  • Genomic structure, sequence, and refined mapping of the human intersectin gene (ITSN), which encompasses 250 kb on chromosome 21q22.1-->q22.2.

    Guipponi M, Scott HS, Hattori M, Ishii K, Sakaki Y and Antonarakis SE

    Laboratory of Human Molecular Genetics, University of Geneva Medical School, Division of Medical Genetics, Cantonal Hospital of Geneva, Geneva, Switzerland.

    The ubiquitously expressed and brain-specific human intersectin (ITSN) isoforms are scaffold proteins probably involved in general endocytosis and synaptic vesicle recycling, respectively. Here, analysis of 21q22.1-->q22.2 genomic sequence revealed that ITSN consists of 41 exons spanning approximately 250 kb and maps between GART and D21S325. The probable function of the ITSN isoforms and mapping position of ITSN suggest that disproportionate expression of this gene may be implicated in the phenotypic characteristics of Down syndrome.

    Cytogenetics and cell genetics 1998;83;3-4;218-20

  • The SH3D1A gene maps to human chromosome 21q22.1-->q22.2.

    Chen H and Antonarakis SE

    Department of Genetics and Microbiology, University of Geneva Medical School, Switzerland.

    Exon trapping was used to identify portions of genes on human chromosome 21. BLAST search of databases revealed that the trapped sequence hmc02a08 (one of 559 different trapped exons) was identical to a region of GenBank entry U61166 for an SH3 (Src-homology) domain-containing gene SH3D1A (formerly called SH3P17; Sparks et al., 1996). We subsequently mapped this gene to YACs and cosmids within 21q22.1-->q22.2 between DNA markers D21S319 and D21S65 using hybridization and PCR amplification.

    Cytogenetics and cell genetics 1997;78;3-4;213-5

  • Cloning of ligand targets: systematic isolation of SH3 domain-containing proteins.

    Sparks AB, Hoffman NG, McConnell SJ, Fowlkes DM and Kay BK

    Department of Biology, University of North Carolina, Chapel Hill 27599, USA.

    Based on the prevalence of modular protein domains, such as Src homology domain 3 and 2 (SH3 and SH2), among important signaling molecules, we have sought to identify new SH3 domain-containing proteins. However, modest sequence similarity among these domains restricts the use of DNA-based methods for this purpose. To circumvent this limitation, we have developed a functional screen that permits the rapid cloning of modular domains based on their ligand-binding activity. Using operationally defined SH3 ligands from combinatorial peptide libraries, we screened a series of mouse and human cDNA expression libraries. We found that 69 of the 74 clones isolated encode at least one SH3 domain. These clones encode 18 different SH3-containing proteins, 10 of which have not been described previously. The isolation of entire repertoires of modular domain-containing proteins will prove invaluable in genome analysis and in bringing new targets into drug discovery programs.

    Nature biotechnology 1996;14;6;741-4

Gene lists (6)

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

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