G2Cdb::Gene report

Gene id
G00001588
Gene symbol
DNM1 (HGNC)
Species
Homo sapiens
Description
dynamin 1
Orthologue
G00000339 (Mus musculus)

Databases (9)

Curated Gene
OTTHUMG00000020733 (Vega human gene)
Gene
ENSG00000106976 (Ensembl human gene)
1759 (Entrez Gene)
33 (G2Cdb plasticity & disease)
DNM1 (GeneCards)
Literature
602377 (OMIM)
Marker Symbol
HGNC:2972 (HGNC)
Protein Expression
5920 (human protein atlas)
Protein Sequence
Q05193 (UniProt)

Literature (87)

Pubmed - other

  • Membrane insertion of the pleckstrin homology domain variable loop 1 is critical for dynamin-catalyzed vesicle scission.

    Ramachandran R, Pucadyil TJ, Liu YW, Acharya S, Leonard M, Lukiyanchuk V and Schmid SL

    Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. rxr275@case.edu

    The GTPase dynamin catalyzes the scission of deeply invaginated clathrin-coated pits at the plasma membrane, but the mechanisms governing dynamin-mediated membrane fission remain poorly understood. Through mutagenesis, we have altered the hydrophobic nature of the membrane-inserting variable loop 1 (VL1) of the pleckstrin homology (PH) domain of dynamin-1 and demonstrate that its stable insertion into the lipid bilayer is critical for high membrane curvature generation and subsequent membrane fission. Dynamin PH domain mutants defective in curvature generation regain function when assayed on precurved membrane templates in vitro, but they remain defective in the scission of clathrin-coated pits in vivo. These results demonstrate that, in concert with dynamin self-assembly, PH domain membrane insertion is essential for fission and vesicle release in vitro and for clathrin-mediated endocytosis in vivo.

    Funded by: NIGMS NIH HHS: R01 GM042455; NIMH NIH HHS: R01 MH061345, R37 MH061345, R37 MH61345

    Molecular biology of the cell 2009;20;22;4630-9

  • A possible effector role for the pleckstrin homology (PH) domain of dynamin.

    Bethoney KA, King MC, Hinshaw JE, Ostap EM and Lemmon MA

    Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA.

    The large GTPase dynamin plays a key role in clathrin-mediated endocytosis in animal cells, although its mechanism of action remains unclear. Dynamins 1, 2, and 3 contain a pleckstrin homology (PH) domain that binds phosphoinositides with a very low affinity (K(D) > 1 mM), and this interaction appears to be crucial for function. These observations prompted the suggestion that an array of PH domains drives multivalent binding of dynamin oligomers to phosphoinositide-containing membranes. Although in vitro experiments reported here are consistent with this hypothesis, we find that PH domain mutations that abolish dynamin function do not alter localization of the protein in transfected cells, indicating that the PH domain does not play a simple targeting role. An alternative possibility is suggested by the geometry of dynamin helices resolved by electron microscopy. Even with one phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P(2)] molecule bound per PH domain, these dynamin assemblies will elevate the concentration of PtdIns(4,5)P(2) at coated pit necks, and effectively cluster (or sequester) this phosphoinositide. In vitro fluorescence quenching studies using labeled phosphoinositides are consistent with dynamin-induced PtdIns(4,5)P(2) clustering. We therefore propose that the ability of dynamin to alter the local distribution of PtdIns(4,5)P(2) could be crucial for the role of this GTPase in promoting membrane scission during clathrin-mediated endocytosis. PtdIns(4,5)P(2) clustering could promote vesicle scission through direct effects on membrane properties, or might play a role in dynamin's ability to regulate actin polymerization.

    Funded by: Intramural NIH HHS; NIGMS NIH HHS: R01 GM057247, R01 GM078345, R01-GM078345, R01-GM57247

    Proceedings of the National Academy of Sciences of the United States of America 2009;106;32;13359-64

  • An intramolecular signaling element that modulates dynamin function in vitro and in vivo.

    Chappie JS, Acharya S, Liu YW, Leonard M, Pucadyil TJ and Schmid SL

    Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

    Dynamin exhibits a high basal rate of GTP hydrolysis that is enhanced by self-assembly on a lipid template. Dynamin's GTPase effector domain (GED) is required for this stimulation, though its mechanism of action is poorly understood. Recent structural work has suggested that GED may physically dock with the GTPase domain to exert its stimulatory effects. To examine how these interactions activate dynamin, we engineered a minimal GTPase-GED fusion protein (GG) that reconstitutes dynamin's basal GTPase activity and utilized it to define the structural framework that mediates GED's association with the GTPase domain. Chemical cross-linking of GG and mutagenesis of full-length dynamin establishes that the GTPase-GED interface is comprised of the N- and C-terminal helices of the GTPase domain and the C-terminus of GED. We further show that this interface is essential for structural stability in full-length dynamin. Finally, we identify mutations in this interface that disrupt assembly-stimulated GTP hydrolysis and dynamin-catalyzed membrane fission in vitro and impair the late stages of clathrin-mediated endocytosis in vivo. These data suggest that the components of the GTPase-GED interface act as an intramolecular signaling module, which we term the bundle signaling element, that can modulate dynamin function in vitro and in vivo.

    Funded by: NCRR NIH HHS: P41 RR017573, P41 RR17573; NIGMS NIH HHS: GM042455, R01 GM042455; NIMH NIH HHS: F31 MH081419, MH061345, MH081419, R01 MH061345, R37 MH061345

    Molecular biology of the cell 2009;20;15;3561-71

  • Proteomic analysis of dorsolateral prefrontal cortex indicates the involvement of cytoskeleton, oligodendrocyte, energy metabolism and new potential markers in schizophrenia.

    Martins-de-Souza D, Gattaz WF, Schmitt A, Maccarrone G, Hunyadi-Gulyás E, Eberlin MN, Souza GH, Marangoni S, Novello JC, Turck CW and Dias-Neto E

    Laboratório de Neurociências, Instituto de Psiquiatria, Faculdade de Medicina da USP, Rua Dr. Ovídio Pires de Campos, SP, Brazil. martins@mpipsykl.mpg.de

    Schizophrenia is likely to be a consequence of serial alterations in a number of genes that, together with environmental factors, will lead to the establishment of the illness. The dorsolateral prefrontal cortex (Brodmann's Area 46) is implicated in schizophrenia and executes high functions such as working memory, differentiation of conflicting thoughts, determination of right and wrong concepts, correct social behavior and personality expression. We performed a comparative proteome analysis using two-dimensional gel electrophoresis of pools from 9 schizophrenia and 7 healthy control patients' dorsolateral prefrontal cortex aiming to identify, by mass spectrometry, alterations in protein expression that could be related to the disease. In schizophrenia-derived samples, our analysis revealed 10 downregulated and 14 upregulated proteins. These included alterations previously implicated in schizophrenia, such as oligodendrocyte-related proteins (myelin basic protein and transferrin), as well as malate dehydrogenase, aconitase, ATP synthase subunits and cytoskeleton-related proteins. Also, six new putative disease markers were identified, including energy metabolism, cytoskeleton and cell signaling proteins. Our data not only reinforces the involvement of proteins previously implicated in schizophrenia, but also suggests new markers, providing further information to foster the comprehension of this important disease.

    Journal of psychiatric research 2009;43;11;978-86

  • Detection of genetic association and a functional polymorphism of dynamin 1 gene with nicotine dependence in European and African Americans.

    Xu Q, Huang W, Payne TJ, Ma JZ and Li MD

    Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA 22911, USA.

    Although it has been documented that dynamin 1 gene (DNM1) is significantly modulated by nicotine in animal models, its association with nicotine dependence (ND) in human population remained to be unexplored. To determine whether DNM1 is associated with ND, in this study, we genotyped seven single-nucleotide polymorphisms (SNPs) within this gene in 602 nuclear families of either African-American (AA) or European-American (EA) origin. Individual SNP-based association analysis revealed a significant association of SNP rs3003609 with smoking quantity (SQ; P=0.0031) and Heaviness of Smoking Index (HSI; P=0.0042) in the EA sample. Furthermore, our haplotype-based association analyses indicated that haplotypes T-G-T, formed by rs2502731-rs2229917-rs3003609 (at a frequency of 54%), G-T-A, formed by rs2229917-rs3003609-rs16930313 (at a frequency of 52%), and T-A-G, formed by rs3003609-rs16930313-rs7022174 (at a frequency of 52%) are significantly associated with SQ (Z=-2.44 to -2.92; P=0.015-0.0055) and HSI (Z=-2.52 to -2.67; P=0.012-0.0076) in the EA sample. In the AA sample, another haplotype, G-T-A, formed by rs7875406-rs2502731-rs2229917, at a frequency of 12% was significantly associated with SQ (Z=-2.58; P=0.0098). Finally, by using in vitro gene expression assays, we demonstrated that the T allele of rs3003609 in the exon 9 of DNM1 significantly decreases the expression of DNM1, by 27.1% at the mRNA and 22.0% at the protein level, suggesting that rs3003609 represents a functional polymorphism affecting DNM1 expression and may partly contributed to the observed association of the gene with ND in our samples. Taken together, our findings indicate that DNM1 is likely involved in the etiology of ND and represents a plausible candidate for further investigation in independent samples.

    Funded by: NIDA NIH HHS: DA-12844, DA-13783, R01 DA012844, R01 DA012844-08, R01 DA013783, R01 DA013783-10

    Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 2009;34;5;1351-9

  • NSF, Unc-18-1, dynamin-1 and HSP90 are inclusion body components in neuronal intranuclear inclusion disease identified by anti-SUMO-1-immunocapture.

    Pountney DL, Raftery MJ, Chegini F, Blumbergs PC and Gai WP

    School of Medical Science, Griffith Institute of Health and Medical Research, Griffith University, Gold Coast Campus, Queensland, QLD, 4222, Australia. d.pountney@griffith.edu.au

    Neuronal intranuclear inclusion disease, a progressive ataxia that may be familial or sporadic, is characterized by numerous neuronal intranuclear inclusion bodies similar to those found in polyglutamine repeat diseases. Previously, we found that the intranuclear inclusion bodies are intensely immunopositive for SUMO-1, a protein which covalently conjugates to other proteins in a similar way to ubiquitin. To identify the SUMO-1-associated proteins in the inclusion bodies, we isolated intranuclear inclusion bodies from fresh, frozen brain tissue of a case with familial neuronal intranuclear inclusion disease and solubilized the proteins. SUMO-1-associated inclusion body proteins were then immunocaptured using an anti-SUMO-1 antibody. The proteins, NSF, dynamin-1 and Unc-18-1 (rbSEC1), involved in membrane trafficking of proteins, and the chaperone HSP90, were identified following anti-SUMO-1-immunocapture by using tandem mass spectrometry and database searching. Immunohistochemistry of brain sections and crude brain homogenates of three cases of familial neuronal intranuclear inclusion disease confirmed the presence of these proteins in intranuclear inclusions.

    Acta neuropathologica 2008;116;6;603-14

  • Molecular genetics of adult ADHD: converging evidence from genome-wide association and extended pedigree linkage studies.

    Lesch KP, Timmesfeld N, Renner TJ, Halperin R, Röser C, Nguyen TT, Craig DW, Romanos J, Heine M, Meyer J, Freitag C, Warnke A, Romanos M, Schäfer H, Walitza S, Reif A, Stephan DA and Jacob C

    ADHD Clinical Research Program, Molecular and Clinical Psychobiology, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Fuechsleinstr. 15, 97080, Wuerzburg, Germany. kplesch@mail.uni-wuerzburg.de

    A genome-wide association (GWA) study with pooled DNA in adult attention-deficit/hyperactivity disorder (ADHD) employing approximately 500K SNP markers identifies novel risk genes and reveals remarkable overlap with findings from recent GWA scans in substance use disorders. Comparison with results from our previously reported high-resolution linkage scan in extended pedigrees confirms several chromosomal loci, including 16q23.1-24.3 which also reached genome-wide significance in a recent meta-analysis of seven linkage studies (Zhou et al. in Am J Med Genet Part B, 2008). The findings provide additional support for a common effect of genes coding for cell adhesion molecules (e.g., CDH13, ASTN2) and regulators of synaptic plasticity (e.g., CTNNA2, KALRN) despite the complex multifactorial etiologies of adult ADHD and addiction vulnerability.

    Journal of neural transmission (Vienna, Austria : 1996) 2008;115;11;1573-85

  • Pockets of short-range transient order and restricted topological heterogeneity in the guanidine-denatured state ensemble of GED of dynamin.

    Chugh J, Sharma S and Hosur RV

    Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India.

    The nature and variety in the denatured state of a protein, a non-native state under a given set of conditions, has been a subject of intense debate. Here, using multidimensional NMR, we have characterized the 6 M Gdn-HCl-denatured state of GED, the assembly domain of dynamin. Even under such strongly denaturing conditions, we detected the presence of conformations in slow exchange on the NMR chemical shift time scale. Although the GED oligomer as well as the SDS-denatured monomeric GED were seen to be predominantly helical [Chugh et al. (2006) FEBS J. 273, 388-397], the 6 M Gdn-HCl-denatured GED has largely beta-structural preferences. However, against such a background, we could detect the presence of a population with a short helical stretch (Arg42-Ile47) in the ensemble. The 1H-1H NOEs suggested presence of pockets of transient short-range order along the chain. Put together these segments may lead to a rather small number of interconverting topologically distinguishable ensembles. Spectral density analysis of 15N relaxation rates and {1H}-15N NOE, measured at 600 and 800 MHz, and comparison of J(0) with hydrophobic patches calculated using AABUF approach, indicated presence of four domains of slow motions. These coincided to a large extent with those showing significant Rex. Additionally, a proline residue in the connection between two of these domains seems to cause a fast hinge motion. These observations help enhance our understanding of protein denatured states, and of folding concepts, in general.

    Biochemistry 2007;46;42;11819-32

  • Systematic identification of SH3 domain-mediated human protein-protein interactions by peptide array target screening.

    Wu C, Ma MH, Brown KR, Geisler M, Li L, Tzeng E, Jia CY, Jurisica I and Li SS

    Department of Biochemistry and the Siebens-Drake Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.

    Systematic identification of direct protein-protein interactions is often hampered by difficulties in expressing and purifying the corresponding full-length proteins. By taking advantage of the modular nature of many regulatory proteins, we attempted to simplify protein-protein interactions to the corresponding domain-ligand recognition and employed peptide arrays to identify such binding events. A group of 12 Src homology (SH) 3 domains from eight human proteins (Swiss-Prot ID: SRC, PLCG1, P85A, NCK1, GRB2, FYN, CRK) were used to screen a peptide target array composed of 1536 potential ligands, which led to the identification of 921 binary interactions between these proteins and 284 targets. To assess the efficiency of the peptide array target screening (PATS) method in identifying authentic protein-protein interactions, we examined a set of interactions mediated by the PLCgamma1 SH3 domain by coimmunoprecipitation and/or affinity pull-downs using full-length proteins and achieved a 75% success rate. Furthermore, we characterized a novel interaction between PLCgamma1 and hematopoietic progenitor kinase 1 (HPK1) identified by PATS and demonstrated that the PLCgamma1 SH3 domain negatively regulated HPK1 kinase activity. Compared to protein interactions listed in the online predicted human interaction protein database (OPHID), the majority of interactions identified by PATS are novel, suggesting that, when extended to the large number of peptide interaction domains encoded by the human genome, PATS should aid in the mapping of the human interactome.

    Proteomics 2007;7;11;1775-85

  • The Cbl-interacting protein TULA inhibits dynamin-dependent endocytosis.

    Bertelsen V, Breen K, Sandvig K, Stang E and Madshus IH

    Institute of Pathology, Faculty Division Rikshospitalet, University of Oslo, Rikshospitalet-Radiumhospitalet Medical Centre, 0027 Oslo, Norway.

    The Cbl- and ubiquitin-interacting protein T-cell ubiquitin ligand (TULA) has been demonstrated to inhibit endocytosis and downregulation of ligand-activated EGF receptor (EGFR) by impairing Cbl-induced ubiquitination. We presently report that TULA additionally inhibited clathrin-dependent endocytosis in general, as both uptake of transferrin (Tf) and low-density lipoprotein (LDL) was inhibited. Additionally, endocytosis of the raft proteins CD59 and major histocompatibility complex class I (MHC-I), which we demonstrate were mainly endocytosed clathrin-independently, but dynamin-dependently, was blocked in cells overexpressing TULA. By contrast, the uptake of ricin, which is mainly endocytosed clathrin- and dynamin-independently, was not affected by overexpressed TULA. Consistently, TULA and dynamin co-immunoprecipitated and colocalized intracellularly, and upon overexpression of dynamin the TULA-mediated inhibitory effect on endocytosis of Tf, LDL, CD59 and MHC-I was counteracted. Overexpressed dynamin did not restore ubiquitination of the EGFR, and consistently dynamin did not rescue endocytosis of the EGFR in cells overexpressing TULA. We conclude that TULA inhibits both clathrin-dependent and clathrin-independent endocytic pathways by functionally sequestering dynamin via the SH3 domain of TULA binding proline-rich sequences in dynamin.

    Experimental cell research 2007;313;8;1696-709

  • The dynamin middle domain is critical for tetramerization and higher-order self-assembly.

    Ramachandran R, Surka M, Chappie JS, Fowler DM, Foss TR, Song BD and Schmid SL

    Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

    The large multidomain GTPase dynamin self-assembles around the necks of deeply invaginated coated pits at the plasma membrane and catalyzes vesicle scission by mechanisms that are not yet completely understood. Although a structural role for the 'middle' domain in dynamin function has been suggested, it has not been experimentally established. Furthermore, it is not clear whether this putative function pertains to dynamin structure in the unassembled state or to its higher-order self-assembly or both. Here, we demonstrate that two mutations in this domain, R361S and R399A, disrupt the tetrameric structure of dynamin in the unassembled state and impair its ability to stably bind to and nucleate higher-order self-assembly on membranes. Consequently, these mutations also impair dynamin's assembly-dependent stimulated GTPase activity.

    Funded by: NCI NIH HHS: R21 CA104046, R21.CA104046; NIGMS NIH HHS: R01 GM042455, R01.GM42455

    The EMBO journal 2007;26;2;559-66

  • Domain requirements for an endocytosis-independent, isoform-specific function of dynamin-2.

    Soulet F, Schmid SL and Damke H

    Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

    Endocytosis is inhibited by overexpression of either dynamin-1 or dynamin-2 mutants because both isoforms form heterotetramers with endogenous dynamin-2 and interfere with its function. By contrast, other phenotypes, which are specifically triggered by overexpression of dynamin-2, but not dynamin-1 are likely to reflect endocytosis-independent, dynamin-2-specific functions and/or interactions. Using Dyn2/Dyn1 chimeras, we explored the structural requirements for a readily quantifiable, isoform-specific function of dynamin-2, the activation of caspase-3 to trigger apoptosis. Strikingly, swapping the highly homologous GTPase domain of dynamin-2 into dynamin-1 was sufficient to confer caspase-3 activation. Moreover, assembly-defective mutations in GED, dynamin's GAP/assembly domain, that inhibit endocytosis enhance caspase-3 activation. Thus, this dynamin-2-specific function is mechanistically distinct from and independent of its role in endocytosis. These findings have important implications for interpreting dynamin-2 dependent phenotypes in overexpression studies.

    Funded by: NCI NIH HHS: R21-CA104046; NIGMS NIH HHS: R01-GM42455

    Experimental cell research 2006;312;18;3539-45

  • The phox homology domain of phospholipase D activates dynamin GTPase activity and accelerates EGFR endocytosis.

    Lee CS, Kim IS, Park JB, Lee MN, Lee HY, Suh PG and Ryu SH

    Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, South Korea.

    Dynamin is a large GTP-binding protein that mediates endocytosis by hydrolyzing GTP. Previously, we reported that phospholipase D2 (PLD2) interacts with dynamin in a GTP-dependent manner. This implies that PLD may regulate the GTPase cycle of dynamin. Here, we show that PLD functions as a GTPase activating protein (GAP) through its phox homology domain (PX), which directly activates the GTPase domain of dynamin, and that the arginine residues in the PLD-PX are vital for this GAP function. Moreover, wild-type PLD-PX, but not mutated PLD-PXs defective for GAP function in vitro, increased epidermal growth factor receptor (EGFR) endocytosis at physiological EGF concentrations. In addition, the silencing of PLDs was shown to retard EGFR endocytosis and the addition of wild-type PLDs or lipase-inactive PLDs, but not PLD1 mutants with defective GAP activity for dynamin in vitro, resulted in the recovery of EGFR endocytosis. These findings suggest that PLD, functioning as an intermolecular GAP for dynamin, accelerates EGFR endocytosis. Moreover, we determined that the phox homology domain itself had GAP activity - a novel function in addition to its role as a binding motif for proteins or lipids.

    Nature cell biology 2006;8;5;477-84

  • Identification of VCP/p97, carboxyl terminus of Hsp70-interacting protein (CHIP), and amphiphysin II interaction partners using membrane-based human proteome arrays.

    Grelle G, Kostka S, Otto A, Kersten B, Genser KF, Müller EC, Wälter S, Böddrich A, Stelzl U, Hänig C, Volkmer-Engert R, Landgraf C, Alberti S, Höhfeld J, Strödicke M and Wanker EE

    Max-Delbrück-Centrum für Molekulare Medizin, Robert-Rössle-Strasse 10, D-13125 Berlin-Buch, Germany.

    Proteins mediate their biological function through interactions with other proteins. Therefore, the systematic identification and characterization of protein-protein interactions have become a powerful proteomic strategy to understand protein function and comprehensive cellular regulatory networks. For the screening of valosin-containing protein, carboxyl terminus of Hsp70-interacting protein (CHIP), and amphiphysin II interaction partners, we utilized a membrane-based array technology that allows the identification of human protein-protein interactions with crude bacterial cell extracts. Many novel interaction pairs such as valosin-containing protein/autocrine motility factor receptor, CHIP/caytaxin, or amphiphysin II/DLP4 were identified and subsequently confirmed by pull-down, two-hybrid and co-immunoprecipitation experiments. In addition, assays were performed to validate the interactions functionally. CHIP e.g. was found to efficiently polyubiquitinate caytaxin in vitro, suggesting that it might influence caytaxin degradation in vivo. Using peptide arrays, we also identified the binding motifs in the proteins DLP4, XRCC4, and fructose-1,6-bisphosphatase, which are crucial for the association with the Src homology 3 domain of amphiphysin II. Together these studies indicate that our human proteome array technology permits the identification of protein-protein interactions that are functionally involved in neurodegenerative disease processes, the degradation of protein substrates, and the transport of membrane vesicles.

    Molecular & cellular proteomics : MCP 2006;5;2;234-44

  • Nitric oxide regulates endocytosis by S-nitrosylation of dynamin.

    Wang G, Moniri NH, Ozawa K, Stamler JS and Daaka Y

    Department of Surgery, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA.

    The GTPase dynamin regulates endocytic vesicle budding from the plasma membrane, but the molecular mechanisms involved remain incompletely understood. We report that dynamin, which interacts with NO synthase, is S-nitrosylated at a single cysteine residue (C607) after stimulation of the beta(2) adrenergic receptor. S-nitrosylation increases dynamin self-assembly and GTPase activity and facilitates its redistribution to the membrane. A mutant protein bearing a C607A substitution does not self-assemble properly or increase its enzymatic activity in response to NO. In NO-generating cells, expression of dynamin C607A, like the GTPase-deficient dominant-negative K44A dynamin, inhibits both beta(2) adrenergic receptor internalization and bacterial invasion. Furthermore, exogenous or endogenously produced NO enhances internalization of both beta(2) adrenergic and epidermal growth factor receptors. Thus, NO regulates endocytic vesicle budding by S-nitrosylation of dynamin. Collectively, our data suggest a general NO-dependent mechanism by which the trafficking of receptors may be regulated and raise the idea that pathogenic microbes and viruses may induce S-nitrosylation of dynamin to facilitate cellular entry.

    Funded by: NIGMS NIH HHS: GM 62231, R01 GM062231

    Proceedings of the National Academy of Sciences of the United States of America 2006;103;5;1295-300

  • 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

  • Dynamin forms a Src kinase-sensitive complex with Cbl and regulates podosomes and osteoclast activity.

    Bruzzaniti A, Neff L, Sanjay A, Horne WC, De Camilli P and Baron R

    Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA. angela.bruzzaniti@yale.edu

    Podosomes are highly dynamic actin-containing adhesion structures found in osteoclasts, macrophages, and Rous sarcoma virus (RSV)-transformed fibroblasts. After integrin engagement, Pyk2 recruits Src and the adaptor protein Cbl, forming a molecular signaling complex that is critical for cell migration, and deletion of any molecule in this complex disrupts p 1082 odosome ring formation and/or decreases osteoclast migration. Dynamin, a GTPase essential for endocytosis, is also involved in actin cytoskeleton remodeling and is localized to podosomes where it has a role in actin turnover. We found that dynamin colocalizes with Cbl in the actin-rich podosome belt of osteoclasts and that dynamin forms a complex with Cbl in osteoclasts and when overexpressed in 293VnR or SYF cells. The association of dynamin with Cbl in osteoclasts was decreased by Src tyrosine kinase activity and we found that destabilization of the dynamin-Cbl complex involves the recruitment of Src through the proline-rich domain of Cbl. Overexpression of dynamin increased osteoclast bone resorbing activity and migration, whereas overexpression of dynK44A decreased osteoclast resorption and migration. These studies suggest that dynamin, Cbl, and Src coordinately participate in signaling complexes that are important in the assembly and remodeling of the actin cytoskeleton, leading to changes in osteoclast adhesion, migration, and resorption.

    Funded by: NIAMS NIH HHS: AR42927, R01 AR042927

    Molecular biology of the cell 2005;16;7;3301-13

  • 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

  • SNX9 regulates dynamin assembly and is required for efficient clathrin-mediated endocytosis.

    Soulet F, Yarar D, Leonard M and Schmid SL

    Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

    Dynamin, a central player in clathrin-mediated endocytosis, interacts with several functionally diverse SH3 domain-containing proteins. However, the role of these interactions with regard to dynamin function is poorly defined. We have investigated a recently identified protein partner of dynamin, SNX9, sorting nexin 9. SNX9 binds directly to both dynamin-1 and dynamin-2. Moreover by stimulating dynamin assembly, SNX9 stimulates dynamin's basal GTPase activity and potentiates assembly-stimulated GTPase activity on liposomes. In fixed cells, we observe that SNX9 partially localizes to clathrin-coated pits. Using total internal reflection fluorescence microscopy in living cells, we detect a transient burst of EGFP-SNX9 recruitment to clathrin-coated pits that occurs during the late stages of vesicle formation and coincides spatially and temporally with a burst of dynamin-mRFP fluorescence. Transferrin internalization is inhibited in HeLa cells after siRNA-mediated knockdown of SNX9. Thus, our results establish that SNX9 is required for efficient clathrin-mediated endocytosis and suggest that it functions to regulate dynamin activity.

    Funded by: NIGMS NIH HHS: GM42455, R01 GM042455; NIMH NIH HHS: MH61345, R01 MH061345, R37 MH061345

    Molecular biology of the cell 2005;16;4;2058-67

  • Immunoaffinity profiling of tyrosine phosphorylation in cancer cells.

    Rush J, Moritz A, Lee KA, Guo A, Goss VL, Spek EJ, Zhang H, Zha XM, Polakiewicz RD and Comb MJ

    Cell Signaling Technology Inc., 166B Cummings Center, Beverly, Massachusetts 01915, USA.

    Tyrosine kinases play a prominent role in human cancer, yet the oncogenic signaling pathways driving cell proliferation and survival have been difficult to identify, in part because of the complexity of the pathways and in part because of low cellular levels of tyrosine phosphorylation. In general, global phosphoproteomic approaches reveal small numbers of peptides containing phosphotyrosine. We have developed a strategy that emphasizes the phosphotyrosine component of the phosphoproteome and identifies large numbers of tyrosine phosphorylation sites. Peptides containing phosphotyrosine are isolated directly from protease-digested cellular protein extracts with a phosphotyrosine-specific antibody and are identified by tandem mass spectrometry. Applying this approach to several cell systems, including cancer cell lines, shows it can be used to identify activated protein kinases and their phosphorylated substrates without prior knowledge of the signaling networks that are activated, a first step in profiling normal and oncogenic signaling networks.

    Funded by: NCI NIH HHS: 1R43CA101106

    Nature biotechnology 2005;23;1;94-101

  • Dynamin GTPase domain mutants that differentially affect GTP binding, GTP hydrolysis, and clathrin-mediated endocytosis.

    Song BD, Leonard M and Schmid SL

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

    The GTPase dynamin is essential for clathrin-mediated endocytosis. Unlike most GTPases, dynamin has a low affinity for nucleotide, a high rate of GTP hydrolysis, and can self-assemble, forming higher order structures such as rings and spirals that exhibit up to 100-fold stimulated GTPase activity. The role(s) of GTP binding and/or hydrolysis in endocytosis remain unclear because mutations in the GTPase domain so far studied impair both. We generated a new series of GTPase domain mutants to probe the mechanism of GTP hydrolysis and to further test the role of GTP binding and/or hydrolysis in endocytosis. Each of the mutations had parallel effects on assembly-stimulated and basal GTPase activities. In contrast to previous reports, we find that mutation of Thr-65 to Ala (or Asp or His) dramatically lowered both the rate of assembly-stimulated GTP hydrolysis and the affinity for GTP. The assemblystimulated rate of hydrolysis was lowered by the mutation of Ser-61 to Asp and increased by the mutation of Thr-141 to Ala without significantly altering the Km for GTP. For some mutants and to a lesser extent for WT dynamin, self-assembly dramatically altered the Km for GTP, suggesting that conformational changes in the active site accompany self-assembly. Analysis of transferrin endocytosis rates in cells overexpressing mutant dynamins revealed a stronger correlation with both the basal and assembly-stimulated rates of GTP hydrolysis than with the calculated ratio of dynamin-GTP/free dynamin, suggesting that GTP binding is not sufficient, and GTP hydrolysis is required for clathrin-mediated endocytosis in vivo.

    Funded by: NIGMS NIH HHS: GM42455

    The Journal of biological chemistry 2004;279;39;40431-6

  • A novel dynamin-associating molecule, formin-binding protein 17, induces tubular membrane invaginations and participates in endocytosis.

    Kamioka Y, Fukuhara S, Sawa H, Nagashima K, Masuda M, Matsuda M and Mochizuki N

    Department of Structural Analysis, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan.

    Dynamin associates with a variety of SH3 domain-containing molecules via a C-terminal proline-rich motif and takes part, with them, in endocytic processes. Here, we have investigated a new dynamin-associating molecule, formin-binding protein 17 (FBP17), involved in deforming the plasma membrane and in endocytosis. FBP17 formed tubular invaginations originating from the plasma membrane. Its N-terminal Fer/CIP4 homology domain, a coiled-coil domain, and a proline-rich motif were required for tubular invagination and self-assembly, by which tubular invagination might be induced. Using anti-FBP17 antibody, we detected positive immunoreactions in the testis that were restricted to the germ cells. We also detected FBP17 in the brain by immunoblotting and in situ hybridization. When COS cells expressing enhanced green fluorescent protein-tagged FBP17 were incubated with fluorescently labeled transferrin, epidermal growth factor, and cholera toxin, these molecules co-localized with FBP17-induced tubular invaginations, suggesting that FBP17 is involved in dynamin-mediated endocytosis in both a clathrin-dependent and -independent manner. These observations therefore indicate that FBP17 interacts with dynamin and regulates endocytosis by forming vesicotubular structures.

    The Journal of biological chemistry 2004;279;38;40091-9

  • Phospholipase C-gamma1 is a guanine nucleotide exchange factor for dynamin-1 and enhances dynamin-1-dependent epidermal growth factor receptor endocytosis.

    Choi JH, Park JB, Bae SS, Yun S, Kim HS, Hong WP, Kim IS, Kim JH, Han MY, Ryu SH, Patterson RL, Snyder SH and Suh PG

    Division of Molecular and Life Science, Pohang University of Science and Technology, San 31, Hyojadong, Pohang, Kyungbuk 790-784, Republic of Korea.

    Phospholipase C-gamma1 (PLC-gamma1), which interacts with a variety of signaling molecules through its two Src homology (SH) 2 domains and a single SH3 domain has been implicated in the regulation of many cellular functions. We demonstrate that PLC-gamma1 acts as a guanine nucleotide exchange factor (GEF) of dynamin-1, a 100 kDa GTPase protein, which is involved in clathrin-mediated endocytosis of epidermal growth factor (EGF) receptor. Overexpression of PLC-gamma1 increases endocytosis of the EGF receptor by increasing guanine nucleotide exchange activity of dynamin-1. The GEF activity of PLC-gamma1 is mediated by the direct interaction of its SH3 domain with dynamin-1. EGF-dependent activation of ERK and serum response element (SRE) are both up-regulated in PC12 cells stably overexpressing PLC-gamma1, but knockdown of PLC-gamma1 by siRNA significantly reduces ERK activation. These results establish a new role for PLC-gamma1 in the regulation of endocytosis and suggest that endocytosis of activated EGF receptors may mediate PLC-gamma1-dependent proliferation.

    Journal of cell science 2004;117;Pt 17;3785-95

  • Dynamin interacts with members of the sumoylation machinery.

    Mishra RK, Jatiani SS, Kumar A, Simhadri VR, Hosur RV and Mittal R

    Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400 005, India.

    Dynamin is a GTP-binding protein whose oligomerization-dependent assembly around the necks of lipid vesicles mediates their scission from parent membranes. Dynamin is thus directly involved in the regulation of endocytosis. Sumoylation is a post-translational protein modification whereby the ubiquitin-like modifier Sumo is covalently attached to lysine residues on target proteins by a process requiring the concerted action of an activating enzyme (ubiquitin-activating enzyme), a conjugating enzyme (ubiquitin carrier protein), and a ligating enzyme (ubiquitin-protein isopeptide ligase). Here, we show that dynamin interacts with Sumo-1, Ubc9, and PIAS-1, all of which are members of the sumoylation machinery. Ubc9 and PIAS-1 are known ubiquitin carrier protein and ubiquitin-protein isopeptide ligase enzymes, respectively, for the process of sumoylation. We have identified the coiled-coil GTPase effector domain (GED) of dynamin as the site on dynamin that interacts with Sumo-1, Ubc9, and PIAS-1. Although we saw no evidence of covalent Sumo-1 attachment to dynamin, Sumo-1 and Ubc9 are shown here to inhibit the lipid-dependent oligomerization of dynamin. Expression of Sumo-1 and Ubc9 in mammalian cells down-regulated the dynamin-mediated endocytosis of transferrin, whereas dynamin-independent fluid-phase uptake was not affected. Furthermore, using high resolution NMR spectroscopy, we have identified amino acid residues on Sumo-1 that directly interact with the GED of dynamin. The results suggest that the GED of dynamin may serve as a scaffold that concentrates the sumoylation machinery in the vicinity of potential acceptor proteins.

    The Journal of biological chemistry 2004;279;30;31445-54

  • Time-controlled transcardiac perfusion cross-linking for the study of protein interactions in complex tissues.

    Schmitt-Ulms G, Hansen K, Liu J, Cowdrey C, Yang J, DeArmond SJ, Cohen FE, Prusiner SB and Baldwin MA

    Institute for Neurodegenerative Disease, San Francisco, California 94143, USA. g.schmittulms@utoronto.ca

    Because of their sensitivity to solubilizing detergents, membrane protein assemblies are difficult to study. We describe a protocol that covalently conserves protein interactions through time-controlled transcardiac perfusion cross-linking (tcTPC) before disruption of tissue integrity. To validate tcTPC for identifying protein-protein interactions, we established that tcTPC allowed stringent immunoaffinity purification of the gamma-secretase complex in high salt concentrations and detergents and was compatible with mass spectrometric identification of cross-linked aph-1, presenilin-1 and nicastrin. We then applied tcTPC to identify more than 20 proteins residing in the vicinity of the cellular prion protein (PrPC), suggesting that PrP is embedded in specialized membrane regions with a subset of molecules that, like PrP, use a glycosylphosphatidylinositol anchor for membrane attachment. Many of these proteins have been implicated in cell adhesion/neuritic outgrowth, and harbor immunoglobulin C2 and fibronectin type III-like motifs.

    Funded by: NCRR NIH HHS: NCRR RR01614; NIA NIH HHS: AG010770, AG02132

    Nature biotechnology 2004;22;6;724-31

  • The granzyme B-serglycin complex from cytotoxic granules requires dynamin for endocytosis.

    Veugelers K, Motyka B, Frantz C, Shostak I, Sawchuk T and Bleackley RC

    Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.

    Cytotoxic T lymphocytes and natural killer cells destroy target cells via the directed exocytosis of lytic effector molecules such as perforin and granzymes. The mechanism by which these proteins enter targets is uncertain. There is ongoing debate over whether the most important endocytic mechanism is nonspecific or is dependent on the cation-independent mannose 6-phosphate receptor. This study tested whether granzyme B endocytosis is facilitated by dynamin, a key factor in many endocytic pathways. Uptake of and killing by the purified granzyme B molecule occurred by both dynamin-dependent and -independent mechanisms. However most importantly, serglycin-bound granzyme B in high-molecular-weight degranulate material from cytotoxic T lymphocytes predominantly followed a dynamin-dependent pathway to kill target cells. Similarly, killing by live cytotoxic T lymphocytes was attenuated by a defect in the dynamin endocytic pathway, and in particular, the pathways characteristically activated by granzyme B were affected. We therefore propose a model where degranulated serglycin-bound granzymes require dynamin for uptake.

    Blood 2004;103;10;3845-53

  • An assembly-incompetent mutant establishes a requirement for dynamin self-assembly in clathrin-mediated endocytosis in vivo.

    Song BD, Yarar D and Schmid SL

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

    Dynamin GTPase activity is required for its biological function in clathrin-mediated endocytosis; however, the role of self-assembly has not been unambiguously established. Indeed, overexpression of a dynamin mutant, Dyn1-K694A, with impaired ability to self-assemble has been shown to stimulate endocytosis in HeLa cells (Sever et al., Nature 1999, 398, 481). To identify new, assembly-incompetent mutants of dynamin 1, we made point mutations in the GTPase effector/assembly domain (GED) and tested for their effects on self-assembly and clathrin-mediated endocytosis. Mutation of three residues, I690, K694, and I697, suggests that interactions with an amphipathic helix in GED are required for self-assembly. In particular, Dyn1-I690K failed to exhibit detectable assembly-stimulated GTPase activity under all assay conditions. Overexpression of this assembly-incompetent mutant inhibited transferrin endocytosis as potently as the GTPase-defective dominant-negative mutant, Dyn1-K44A. However, worm-like endocytic intermediates accumulated in cells expressing Dyn1-I690K that were structurally distinct from long tubules that accumulated in cells expressing Dyn1-K44A. Together these results provide new structural insight into the role of GED in self-assembly and assembly-stimulated GTPase activity and establish that dynamin self-assembly is essential for clathrin-mediated endocytosis.

    Funded by: NHLBI NIH HHS: 5T32 HL 07695, T32 HL007695; NIGMS NIH HHS: GM 42455, R01 GM042455; NIMH NIH HHS: MH 61345, R01 MH061345, R37 MH061345

    Molecular biology of the cell 2004;15;5;2243-52

  • 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

  • Tuba, a novel protein containing bin/amphiphysin/Rvs and Dbl homology domains, links dynamin to regulation of the actin cytoskeleton.

    Salazar MA, Kwiatkowski AV, Pellegrini L, Cestra G, Butler MH, Rossman KL, Serna DM, Sondek J, Gertler FB and De Camilli P

    Department of Cell Biology and the Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06519, USA.

    Tuba is a novel scaffold protein that functions to bring together dynamin with actin regulatory proteins. It is concentrated at synapses in brain and binds dynamin selectively through four N-terminal Src homology-3 (SH3) domains. Tuba binds a variety of actin regulatory proteins, including N-WASP, CR16, WAVE1, WIRE, PIR121, NAP1, and Ena/VASP proteins, via a C-terminal SH3 domain. Direct binding partners include N-WASP and Ena/VASP proteins. Forced targeting of the C-terminal SH3 domain to the mitochondrial surface can promote accumulation of F-actin around mitochondria. A Dbl homology domain present in the middle of Tuba upstream of a Bin/amphiphysin/Rvs (BAR) domain activates Cdc42, but not Rac and Rho, and may thus cooperate with the C terminus of the protein in regulating actin assembly. The BAR domain, a lipid-binding module, may functionally replace the pleckstrin homology domain that typically follows a Dbl homology domain. The properties of Tuba provide new evidence for a close functional link between dynamin, Rho GTPase signaling, and the actin cytoskeleton.

    Funded by: NCI NIH HHS: CA46128; NIGMS NIH HHS: GM58801, GM62299; NINDS NIH HHS: NS36251

    The Journal of biological chemistry 2003;278;49;49031-43

  • Syntaphilin binds to dynamin-1 and inhibits dynamin-dependent endocytosis.

    Das S, Gerwin C and Sheng ZH

    Synaptic Function Unit, NINDS, National Institutes of Health, Bethesda, Maryland 20892-4154, USA.

    Syntaphilin is a brain-specific syntaxin-binding partner first characterized as an inhibitor of SNARE complex formation and neurotransmitter release. Here we show that syntaphilin also binds to dynamin-1 and through this interaction inhibits dynamin-mediated endocytosis. Immunoprecipitation studies from cross-linked rat synaptosomes demonstrate that an endogenous syntaphilin-dynamin-1 complex exists independently of dynamin-1 binding to amphiphysin. Functionally, syntaphilin expression inhibits transferrin internalization in COS-7 cells. These data reveal that syntaphilin is an inhibitor of both SNARE-based fusion and dynamin-mediated endocytosis.

    The Journal of biological chemistry 2003;278;42;41221-6

  • Cdk5 is essential for synaptic vesicle endocytosis.

    Tan TC, Valova VA, Malladi CS, Graham ME, Berven LA, Jupp OJ, Hansra G, McClure SJ, Sarcevic B, Boadle RA, Larsen MR, Cousin MA and Robinson PJ

    Cell Signalling Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, NSW 2145, Australia.

    Synaptic vesicle endocytosis (SVE) is triggered by calcineurin-mediated dephosphorylation of the dephosphin proteins. SVE is maintained c4 by the subsequent rephosphorylation of the dephosphins by unidentified protein kinases. Here, we show that cyclin-dependent kinase 5 (Cdk5) phosphorylates dynamin I on Ser 774 and Ser 778 in vitr 1f40 o, which are identical to its endogenous phosphorylation sites in vivo. Cdk5 antagonists and expression of dominant-negative Cdk5 block phosphorylation of dynamin I, but not of amphiphysin or AP180, in nerve terminals and inhibit SVE. Thus Cdk5 has an essential role in SVE and is the first dephosphin kinase identified in nerve terminals.

    Nature cell biology 2003;5;8;701-10

  • Characterization of Endophilin B1b, a brain-specific membrane-associated lysophosphatidic acid acyl transferase with properties distinct from endophilin A1.

    Modregger J, Schmidt AA, Ritter B, Huttner WB and Plomann M

    Center for Biochemistry II, Medical Faculty, Joseph-Stelzmann-Strasse 52, University of Cologne, Germany.

    We have characterized mammalian endophilin B1, a novel member of the endophilins and a representative of their B subgroup. The endophilins B show the same domain organization as the endophilins A, which contain an N-terminal domain responsible for lipid binding and lysophosphatidic acid acyl transferase activity, a central coiled-coil domain for oligomerization, a less conserved linker region, and a C-terminal Src homology 3 (SH3) domain. The endophilin B1 gene gives rise to at least three splice variants, endophilin B1a, which shows a widespread tissue distribution, and endophilins B1b and B1c, which appear to be brain-specific. Endophilin B1, like endophilins A, binds to palmitoyl-CoA, exhibits lysophosphatidic acid acyl transferase activity, and interacts with dynamin, amphiphysins 1 and 2, and huntingtin. However, in contrast to endophilins A, endophilin B1 does not bind to synaptojanin 1 and synapsin 1, and overexpression of its SH3 domain does not inhibit transferrin endocytosis. Consistent with this, immunofluorescence analysis of endophilin B1b transfected into fibroblasts shows an intracellular reticular staining, which in part overlaps with that of endogenous dynamin. Upon subcellular fractionation of brain and transfected fibroblasts, endophilin B1 is largely recovered in association with membranes. Together, our results suggest that the action of the endophilins is not confined to the formation of endocytic vesicles from the plasma membrane, with endophilin B1 being associated with, and presumably exerting a functional role at, intracellular membranes.

    The Journal of biological chemistry 2003;278;6;4160-7

  • Dynamin at the actin-membrane interface.

    Orth JD and McNiven MA

    Department of Biochemistry and Molecular Biology and the Center for Basic Research in Digestive Diseases, Mayo Clinic and Foundation, Rochester, MN 55905, USA.

    Many important cellular processes such as phagocytosis, cell motility and endocytosis require the participation of a dynamic and interactive actin cytoskeleton that acts to deform cellular membranes. The extensive family of non-traditional myosins has been implicated in linking the cortical actin gel with the plasma membrane. Recently, however, the dynamins have also been included in these cell processes as a second family of mechanochemical enzymes that self-associate and hydrolyze nucleotides to perform 'work' while linking cellular membranes to the actin cytoskeleton. The dynamins are believed to form large helical polymers from which extend many interactive proline-rich tail domains, and these domains bind to a variety of SH3-domain-containing proteins, many of which appear to be actin-binding proteins. Recent data support the concept that the dynamin family might act as a 'polymeric contractile scaffold' at the interface between biological membranes and filamentous actin.

    Current opinion in cell biology 2003;15;1;31-9

  • The betagamma subunit of heterotrimeric G proteins interacts with RACK1 and two other WD repeat proteins.

    Dell EJ, Connor J, Chen S, Stebbins EG, Skiba NP, Mochly-Rosen D and Hamm HE

    Institute for Neuroscience and Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60613, USA.

    A yeast two-hybrid approach was used to discern possible new effectors for the betagamma subunit of heterotrimeric G proteins. Three of the clones isolated are structurally similar to Gbeta, each exhibiting the WD40 repeat motif. Two of these proteins, the receptor for activated C kinase 1 (RACK1) and the dynein intermediate chain, co-immunoprecipitate with Gbetagamma using an anti-Gbeta antibody. The third protein, AAH20044, has no known function; however, sequence analysis indicates that it is a WD40 repeat protein. Further investigation with RACK1 shows that it not only interacts with Gbeta(1)gamma(1) but also unexpectedly with the transducin heterotrimer Galpha(t)beta(1)gamma(1). Galpha(t) alone does not interact, but it must contribute to the interaction because the apparent EC(50) value of RACK1 for Galpha(t)beta(1)gamma(1) is 3-fold greater than that for Gbeta(1)gamma(1) (0.1 versus 0.3 microm). RACK1 is a scaffold that interacts with several proteins, among which are activated betaIIPKC and dynamin-1 (1). betaIIPKC and dynamin-1 compete with Gbeta(1)gamma(1) and Galpha(t)beta(1)gamma(1) for interaction with RACK1. These findings have several implications: 1) that WD40 repeat proteins may interact with each other; 2) that Gbetagamma interacts differently with RACK1 than with its other known effectors; and/or 3) that the G protein-RACK1 complex may constitute a signaling scaffold important for intracellular responses.

    Funded by: NEI NIH HHS: EY 100291

    The Journal of biological chemistry 2002;277;51;49888-95

  • Clint: a novel clathrin-binding ENTH-domain protein at the Golgi.

    Kalthoff C, Groos S, Kohl R, Mahrhold S and Ungewickell EJ

    Department of Cell Biology, Center of Anatomy, Hannover Medical School, Hannover, Germany.

    We have characterized a novel clathrin-binding 68-kDa epsin N-terminal homology domain (ENTH-domain) protein that we name clathrin interacting protein localized in the trans-Golgi region (Clint). It localizes predominantly to the Golgi region of epithelial cells as well as to more peripheral vesicular structures. Clint colocalizes with AP-1 and clathrin only in the perinuclear area. Recombinantly expressed Clint interacts directly with the gamma-appendage domain of AP-1, with the clathrin N-terminal domain through the peptide motif (423)LFDLM, with the gamma-adaptin ear homology domain of Golgi-localizing, gamma-adaptin ear homology domain 2, with the appendage domain of beta2-adaptin and to a lesser extent with the appendage domain of alpha-adaptin. Moreover, the Clint ENTH-domain asssociates with phosphoinositide-containing liposomes. A significant amount of Clint copurifies with rat liver clathrin-coated vesicles. In rat kidney it is preferentially expressed in the apical region of epithelial cells that line the collecting duct. Clathrin and Clint also colocalize in the apical region of enterocytes along the villi of the small intestine. Apart from the ENTH-domain Clint has no similarities with the epsins AP180/CALM or Hip1/1R. A notable feature of Clint is a carboxyl-terminal methionine-rich domain (Met(427)-Met(605)), which contains >17% methionine. Our results suggest that Clint might participate in the formation of clathrin-coated vesicles at the level of the trans-Golgi network and remains associated with the vesicles longer than clathrin and adaptors.

    Molecular biology of the cell 2002;13;11;4060-73

  • Dynamin2 and cortactin regulate actin assembly and filament organization.

    Schafer DA, Weed SA, Binns D, Karginov AV, Parsons JT and Cooper JA

    Department of Biology, University of Virginia, Charlottesville, VA 22904, USA. das9w@virginia.edu

    The GTPase dynamin is required for endocytic vesicle formation. Dynamin has also been implicated in regulating the actin cytoskeleton, but the mechanism by which it does so is unclear. Through interactions via its proline-rich domain (PRD), dynamin binds several proteins, including cortactin, profilin, syndapin, and murine Abp1, that regulate the actin cytoskeleton. We investigated the interaction of dynamin2 and cortactin in regulating actin assembly in vivo and in vitro. When expressed in cultured cells, a dynamin2 mutant with decreased affinity for GTP decreased actin dynamics within the cortical actin network. Expressed mutants of cortactin that have decreased binding of Arp2/3 complex or dynamin2 also decreased actin dynamics. Dynamin2 influenced actin nucleation by purified Arp2/3 complex and cortactin in vitro in a biphasic manner. Low concentrations of dynamin2 enhanced actin nucleation by Arp2/3 complex and cortactin, and high concentrations were inhibitory. Dynamin2 promoted the association of actin filaments nucleated by Arp2/3 complex and cortactin with phosphatidylinositol 4,5-bisphosphate (PIP2)-containing lipid vesicles. GTP hydrolysis altered the organization of the filaments and the lipid vesicles. We conclude that dynamin2, through an interaction with cortactin, regulates actin assembly and actin filament organization at membranes.

    Funded by: NCI NIH HHS: CA29243; NIGMS NIH HHS: GM 38542, GM55562, R01 GM038542, R01 GM038542-14

    Current biology : CB 2002;12;21;1852-7

  • Dynamin and endocytosis.

    Sever S

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and Dana-Farber Cancer Institute, 1 Jimmy Fund Way, Boston, MA 02115, USA. sanja_sever@dfci.harvard.edu

    The GTPase dynamin is essential for endocytosis, but its mechanism of action remains uncertain. Structures of its GTPase domain, as well as that of assembled dynamin, have led to major advances in understanding the structural basis of its mode of action. Novel data point more clearly than ever towards a role for this protein in the actin cytoskeleton, mitogen-activated protein kinase signaling and apoptosis, suggesting that dynamin might be a signaling GTPase.

    Current opinion in cell biology 2002;14;4;463-7

  • Src-dependent tyrosine phosphorylation regulates dynamin self-assembly and ligand-induced endocytosis of the epidermal growth factor receptor.

    Ahn S, Kim J, Lucaveche CL, Reedy MC, Luttrell LM, Lefkowitz RJ and Daaka Y

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

    Endocytosis of ligand-activated receptors requires dynamin-mediated GTP hydrolysis, which is regulated by dynamin self-assembly. Here, we demonstrate that phosphorylation of dynamin I by c-Src induces its self-assembly and increases its GTPase activity. Electron microscopic analyses reveal that tyrosine-phosphorylated dynamin I spontaneously self-assembles into large stacks of rings. Tyrosine 597 was identified as being phosphorylated both in vitro and in cultured cells following epidermal growth factor receptor stimulation. The replacement of tyrosine 597 with phenylalanine impairs Src kinase-induced dynamin I self-assembly and GTPase activity in vitro. Expression of Y597F dynamin I in cells attenuates agonist-driven epidermal growth factor receptor internalization. Thus, c-Src-mediated tyrosine phosphorylation is required for the function of dynamin in ligand-induced signaling receptor internalization.

    Funded by: NHLBI NIH HHS: R01 HL16037; NIGMS NIH HHS: R01 GM66231

    The Journal of biological chemistry 2002;277;29;26642-51

  • Interactions of phocein with nucleoside-diphosphate kinase, Eps15, and Dynamin I.

    Baillat G, Gaillard S, Castets F and Monneron A

    INSERM U464, Faculté de Médecine Nord, Bd. Pierre Dramard, 13916 Marseille Cedex 20, France.

    Phocein, an intracellular protein interacting with striatin, bears a few homologies with the sigma-subunits of clathrin adaptor proteins (Baillat, G., Moqrich, A., Castets, F., Baude, A., Bailly, Y., Benmerah, A., and Monneron, A. (2001) Mol. Biol. Cell 12, 663-673). Using phocein as a bait in a yeast two-hybrid screen, we identified two novel interacting proteins, nucleoside-diphosphate kinase (NDPK) and Eps15. Immunoprecipitation and pull-down experiments involving native and/or recombinant phocein and, respectively, NDPK and Eps15, biochemically validated their interactions. NDPK and Eps15 were recently shown to be functional neighbors of dynamin. Dynamin I is shown here to directly interact with NDPK through its C-terminal proline-rich domain, whereas recombinant phocein associates with native dynamin I. Immunocytochemical studies of rat embryonic hippocampal neurons demonstrated partial co-localization of phocein and dynamin I. Phocein thus appears to be a component of the complexes involved in some steps of the vesicular traffic machinery.

    The Journal of biological chemistry 2002;277;21;18961-6

  • Dynamin is a minibrain kinase/dual specificity Yak1-related kinase 1A substrate.

    Chen-Hwang MC, Chen HR, Elzinga M and Hwang YW

    Molecular Biology Department, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA.

    The minibrain kinase (Mnbk)/dual specificity Yak 1-related kinase 1A (Dyrk1A) gene is implicated in the mental retardation associated with Down's syndrome. It encodes a proline-directed serine/threonine kinase whose function has yet to be defined. We have used a solid-phase Mnbk/Dyrk1A kinase assay to aid in the search for the cellular Mnbk/Dyrk1A substrates. The assay revealed that rat brain contains two cytosolic proteins, one with a molecular mass of 100 kDa and one with a molecular mass of 140 kDa, that were prominently phosphorylated by Mnbk/Dyrk1A. The 100-kDa protein was purified and identified as dynamin 1. The conclusion was further supported by evidence that a recombinant glutathione S-transferase fusion protein containing dynamin isoform 1aa was phosphorylated by Mnbk/Dyrk1A. In addition to isoform 1aa, Mnbk/Dyrk1A also phosphorylated isoforms 1ab and 2aa but not human MxA protein when analyzed by the solid-phase kinase assay. Upon Mnbk/Dyrk1A phosphorylation, the interaction of dynamin 1 with the Src homology 3 domain of amphiphysin 1 was reduced. However, when Mnbk/Dyrk1A phosphorylation was allowed to proceed more extensively, the phosphorylation enhanced rather than reduced the binding of dynamin 1 to amphiphysin 1. The result suggests that Mnbk/Dyrk1A can play a dual role in regulating the interaction of dynamin 1 with amphiphysin 1. Mnbk/Dyrk1A phosphorylation also reduced the interaction of dynamin with endophilin 1, whereas the same phosphorylation enhanced the binding of dynamin 1 to Grb2. Nevertheless, the dual function of Mnbk/Dyrk1A phosphorylation was not observed for the interaction of dynamin 1 with endophilin 1 or Grb2. The interactions of dynamin with amphiphysin and endophilin are essential for the formation of endocytic complexes; our results suggest that Mnbk/Dyrk1A may function as a regulator controlling the assembly of endocytic apparatus.

    Funded by: NICHD NIH HHS: HD35870, HD38295

    The Journal of biological chemistry 2002;277;20;17597-604

  • The endocytosis-linked protein dynamin associates with caveolin-1 and is tyrosine phosphorylated in response to the activation of a noninternalizing epidermal growth factor receptor mutant.

    Kim YN and Bertics PJ

    Department of Biomolecular Chemistry, University of Wisconsin, 1300 University Avenue, Madison, WI 53706-1532, USA.

    Several studies have shown that an EGF receptor C-terminal truncation at residue 973 (CT973) attenuates ligand-induced receptor endocytosis and is associated with cell transformation. Previously, we have shown that EGF stimulation of murine B82L fibroblasts expressing CT973 EGF receptors can promote the tyrosine phosphorylation of caveolin-1, which is a major component of caveolae membranes. Because dynamin plays an essential role in receptor-mediated endocytosis via clathrin-coated pits and caveolae, and because dynamin has been localized to caveolae, we tested the hypothesis that dynamin associates with caveolin-1 and is differentially modified in response to the abnormal actions of internalization-defective EGF receptors. We found that dynamin coimmunoprecipitates with caveolin-1 in cells containing normal or CT973 EGF receptors, but EGF stimulated the tyrosine phosphorylation of dynamin only in cells expressing truncated/oncogenic EGF receptors. Maximum dynamin phosphorylation was observed within 15 min of EGF administration and decreased thereafter. Furthermore, phosphotyrosine-containing proteins in the dynamin immunocomplexes were observed to be reactive with anticaveolin-1 antibodies. The EGF receptor does not appear to directly phosphorylate dynamin because a Src antagonist, PP1, inhibited the EGF-induced tyrosine phosphorylation of dynamin at a concentration that does not block EGF receptor autophosphorylation. These results provide the first evidence that caveolin-1 and dynamin form a complex, and that the EGF-induced tyrosine phosphorylation of dynamin occurs via a Src inhibitor-sensitive signaling pathway that is associated with the aberrant actions induced by internalization-defective EGF receptors.

    Funded by: NIGMS NIH HHS: R01-GM-53271

    Endocrinology 2002;143;5;1726-31

  • The endophilin-CIN85-Cbl complex mediates ligand-dependent downregulation of c-Met.

    Petrelli A, Gilestro GF, Lanzardo S, Comoglio PM, Migone N and Giordano S

    CNR-CIOS and Department of Genetics, Biology and Biochemistry, University of Torino, 10126 Torino, Italy.

    Ligand-dependent downregulation of tyrosine kinase receptors is a critical step for modulating their activity. Upon ligand binding, hepatocyte growth factor (HGF) receptor (Met) is polyubiquitinated and degraded; however, the mechanisms underlying HGF receptor endocytosis are not yet known. Here we demonstrate that a complex involving endophilins, CIN85 and Cbl controls this process. Endophilins are regulatory components of clathrin-coated vesicle formation. Through their acyl-transferase activity they are thought to modify the membrane phospholipids and induce negative curvature and invagination of the plasma membrane during the early steps of endocytosis. Furthermore, by means of their Src-homology 3 domains, endophilins are able to bind CIN85, a recently identified protein that interacts with the Cbl proto-oncogene. Cbl, in turn, binds and ubiquitinates activated HGF receptor, and by recruiting the endophilin-CIN85 complex, it regulates receptor internalization. Inhibition of complex formation is sufficient to block HGF receptor internalization and to enhance HGF-induced signal transduction and biological responses. These data provide further evidence of a relationship between receptor-mediated signalling and endocytosis, and disclose a novel functional role for Cbl in HGF receptor signalling.

    Nature 2002;416;6877;187-90

  • Dynamin at actin tails.

    Lee E and De Camilli P

    Department of Cell Biology and Howard Hughes Medical Institute, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA.

    Dynamin, the product of the shibire gene of Drosophila, is a GTPase critically required for endocytosis. Some studies have suggested a functional link between dynamin and the actin cytoskeleton. This link is of special interest, because there is evidence implicating actin dynamics in endocytosis. Here we show that endogenous dynamin 2, as well as green fluorescence protein fusion proteins of both dynamin 1 and 2, is present in actin comets generated by Listeria or by type I PIP kinase (PIPK) overexpression. In PIPK-induced tails, dynamin is further enriched at the interface between the tails and the moving organelles. Dynamin mutants harboring mutations in the GTPase domain inhibited nucleation of actin tails induced by PIPK and moderately reduced their speed. Although dynamin localization to the tails required its proline-rich domain, expression of a dynamin mutant lacking this domain also diminished tail formation. In addition, this mutant disrupted a membrane-associated actin scaffold (podosome rosette) previously shown to include dynamin. These findings suggest that dynamin is part of a protein network that controls nucleation of actin from membranes. At endocytic sites, dynamin may couple the fission reaction to the polymerization of an actin pool that functions in the separation of the endocytic vesicles from the plasma membrane.

    Funded by: NCI NIH HHS: CA46128, P01 CA046128; NINDS NIH HHS: NS36251, R01 NS036251, R37 NS036251

    Proceedings of the National Academy of Sciences of the United States of America 2002;99;1;161-6

  • Dynamin: characteristics, mechanism of action and function.

    Wiejak J and Wyroba E

    Nencki Institute of Experimental Biology, Pasteura 3, 02-093 Warszawa, Poland.

    Dynamin - a member of the GTP-ase protein family - is essential for many intracellular membrane trafficking events in multiple endocytic processes. The unique biochemical features of dynamin - especially its propensity to assemble - enable severing the nascent vesicles from the membrane. The mechanism of dynamin's action is still a subject of debate - whether it functions as a mechanochemical enzyme or a regulatory GTPase. The GTPase domain of dynamin contains three GTP-binding motifs. This domain is very conservative across the species, including that recently cloned by us in the unicellular eukaryote Paramecium. Dynamin interacts with a number of partners such as endophilin and proteins involved in coordination of endocytosis with motor molecules. A growing body of evidence indicates that dynamin and dynamin-related proteins are involved both in pathology and protection against human diseases. The most interesting are dynamin-like Mx proteins exhibiting antiviral activity.

    Cellular & molecular biology letters 2002;7;4;1073-80

  • Chloride intracellular channel protein CLIC4 (p64H1) binds directly to brain dynamin I in a complex containing actin, tubulin and 14-3-3 isoforms.

    Suginta W, Karoulias N, Aitken A and Ashley RH

    Department of Biomedical Sciences, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.

    Mammalian chloride intracellular channel (CLIC) (p64-related) proteins are widely expressed, with an unusual dual localization as both soluble and integral membrane proteins. The molecular basis for their cellular localization and ion channel activity remains unclear. To help in addressing these problems, we identified novel rat brain CLIC4 (p64H1) binding partners by affinity chromatography, mass spectrometric analysis and microsequencing. Brain CLIC4 binds dynamin I, alpha-tubulin, beta-actin, creatine kinase and two 14-3-3 isoforms; the interactions are confirmed in vivo by immunoprecipitation. Gel overlay and reverse pull-down assays indicate that the binding of CLIC4 to dynamin I and 14-3-3zeta is direct. In HEK-293 cells, biochemical and immunofluorescence analyses show partial co-localization of recombinant CLIC4 with caveolin and with functional caveolae, which is consistent with a dynamin-associated role for CLIC4 in caveolar endocytosis. We speculate that brain CLIC4 might be involved in the dynamics of neuronal plasma membrane microdomains (micropatches) containing caveolin-like proteins and might also have other cellular roles related to membrane trafficking. Our results provide the basis for new hypotheses concerning novel ways in which CLIC proteins might be associated with cell membrane remodelling, the control of cell shape, and anion channel activity.

    The Biochemical journal 2001;359;Pt 1;55-64

  • The SH2/SH3 adaptor Grb4 transduces B-ephrin reverse signals.

    Cowan CA and Henkemeyer M

    Center for Developmental Biology and Kent Waldrep Foundation Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas 75390-9133, USA.

    Bidirectional signals mediated by membrane-anchored ephrins and Eph receptor tyrosine kinases have important functions in cell-cell recognition events, including those that occur during axon pathfinding and hindbrain segmentation. The reverse signal that is transduced into B-ephrin-expressing cells is thought to involve tyrosine phosphorylation of the signal's short, conserved carboxy-terminal cytoplasmic domain. The Src-homology-2 (SH2) domain proteins that associate with activated tyrosine-phosphorylated B-subclass ephrins have not been identified, nor has a defined cellular response to reverse signals been described. Here we show that the SH2/SH3 domain adaptor protein Grb4 binds to the cytoplasmic domain of B ephrins in a phosphotyrosine-dependent manner. In response to B-ephrin reverse signalling, cells increase FAK catalytic activity, redistribute paxillin, lose focal adhesions, round up, and disassemble F-actin-containing stress fibres. These cellular responses can be blocked in a dominant-negative fashion by expression of the isolated Grb4 SH2 domain. The Grb4 SH3 domains bind a unique set of other proteins that are implicated in cytoskeletal regulation, including the Cbl-associated protein (CAP/ponsin), the Abl-interacting protein-1 (Abi-1), dynamin, PAK1, hnRNPK and axin. These data provide a biochemical pathway whereby cytoskeletal regulators are recruited to Eph-ephrin bidirectional signalling complexes.

    Nature 2001;413;6852;174-9

  • The Eps15 C. elegans homologue EHS-1 is implicated in synaptic vesicle recycling.

    Salcini AE, Hilliard MA, Croce A, Arbucci S, Luzzi P, Tacchetti C, Daniell L, De Camilli P, Pelicci PG, Di Fiore PP and Bazzicalupo P

    Department of Experimental Oncology, European Institute of Oncology, 20141 Milan, Italy.

    Eps15 represents the prototype of a family of evolutionarily conserved proteins that are characterized by the presence of the EH domain, a protein-protein interaction module, and that are involved in many aspects of intracellular vesicular sorting. Although biochemical and functional studies have implicated Eps15 in endocytosis, its function in the endocytic machinery remains unclear. Here we show that the Caenorhabditis elegans gene, zk1248.3 (ehs-1), is the orthologue of Eps15 in nematodes, and that its product, EHS-1, localizes to synaptic-rich regions. ehs-1-impaired worms showed temperature-dependent depletion of synaptic vesicles and uncoordinated movement. These phenotypes could be correlated with a presynaptic defect in neurotransmission. Impairment of EHS-1 function in dyn-1(ky51) worms, which express a mutant form of dynamin and display a temperature-sensitive locomotion defect, resulted in a worsening of the dyn-1 phenotype and uncoordination at the permissive temperature. Thus, ehs-1 and dyn-1 interact genetically. Moreover, mammalian Eps15 and dynamin protein were shown to interact in vivo. Taken together, our results indicate that EHS-1 acts in synaptic vesicle recycling and that its function might be linked to that of dynamin.

    Funded by: Telethon: D.068, D.090, E.0942, GTF01018

    Nature cell biology 2001;3;8;755-60

  • GTPase activity of dynamin and resulting conformation change are essential for endocytosis.

    Marks B, Stowell MH, Vallis Y, Mills IG, Gibson A, Hopkins CR and McMahon HT

    MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.

    Dynamin is a large GTPase with a relative molecular mass of 96,000 (Mr 96K) that is involved in clathrin-mediated endocytosis and other vesicular trafficking processes. Although its function is apparently essential for scission of newly formed vesicles from the plasma membrane, the nature of dynamin's role in the scission process is still unclear. It has been proposed that dynamin is a regulator (similar to classical G proteins) of downstream effectors. Here we report the analysis of several point mutants of dynamin's GTPase effector (GED) and GTPase domains. We show that oligomerization and GTP binding alone, by dynamin, are not sufficient for endocytosis in vivo. Rather, efficient GTP hydrolysis and an associated conformational change are also required. These data argue that dynamin has a mechanochemical function in vesicle scission.

    Nature 2001;410;6825;231-5

  • Dynamin inhibits phosphatidylinositol 3-kinase in hematopoietic cells.

    Harrison-Findik D, Misra S, Jain SK, Keeler ML, Powell KA, Malladi CS, Varticovski L and Robinson PJ

    Institute of Medical and Veterinary Science, Hanson Cancer Centre, Division of Molecular Pathology, Adelaide, Australia.

    Phosphatidylinositol 3-kinase (PI 3-kinase) plays a role in late stages of endocytosis as well as in cellular proliferation and transformation. The SH3 domain of its regulatory p85 subunit stimulates the GTPase activity of dynamin in vitro. Dynamin is a GTPase enzyme required for endocytosis of activated growth factor receptors. An interaction between these proteins has not been demonstrated in vivo. Here, we report that dynamin associates with PI 3-kinase in hematopoietic cells. We detected both p85 and PI 3-kinase activity in dynamin immune complexes from IL-3-dependent BaF3 cells. However, this association was significantly reduced in BaF3 cells transformed with the BCR/abl oncogene. After transformation only a 4-fold increase in PI 3-kinase activity was detected in dynamin immune complexes, whereas grb2 associated activity was elevated 20-fold. Furthermore, dynamin inhibited the activity of both purified recombinant and immunoprecipitated PI 3-kinase. In BaF3 cells expressing a temperature-sensitive mutant of BCR/abl, a significant decrease in p85 and dynamin association was observed 4 h after the induction of BCR/abl activity. In contrast, in IL-3-stimulated parental BaF3 cells, this association was increased. Our results demonstrate an in vivo association of PI 3-kinase with dynamin and this interaction regulates the activity of PI 3-kinase.

    Funded by: NCI NIH HHS: CA 53094

    Biochimica et biophysica acta 2001;1538;1;10-9

  • Division of mitochondria requires a novel DMN1-interacting protein, Net2p.

    Cerveny KL, McCaffery JM and Jensen RE

    Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

    Mitochondria are dynamic organelles that undergo frequent division and fusion, but the molecular mechanisms of these two events are not well understood. Dnm1p, a mitochondria-associated, dynamin-related GTPase was previously shown to mediate mitochondrial fission. Recently, a genome-wide yeast two-hybrid screen identified an uncharacterized protein that interacts with Dnm1p. Cells disrupted in this new gene, which we call NET2, contain a single mitochondrion that consists of a network formed by interconnected tubules, similar to the phenotype of dnm1 Delta cells. NET2 encodes a mitochondria-associated protein with a predicted coiled-coil region and six WD-40 repeats. Immunofluorescence microscopy indicates that Net2p is located in distinct, dot-like structures along the mitochondrial surface, many of which colocalize with the Dnm1 protein. Fluorescence and immunoelectron microscopy shows that Dnm1p and Net2p preferentially colocalize at constriction sites along mitochondrial tubules. Our results suggest that Net2p is a new component of the mitochondrial division machinery.

    Funded by: NIGMS NIH HHS: 2T32GM07445, R01 GM054021, R01-GM54021, T32 GM007445

    Molecular biology of the cell 2001;12;2;309-21

  • All three PACSIN isoforms bind to endocytic proteins and inhibit endocytosis.

    Modregger J, Ritter B, Witter B, Paulsson M and Plomann M

    Institute for Biochemistry II, Medical Faculty, University of Cologne, D-50931 Cologne, Germany.

    The PACSINs are a family of cytoplasmic phosphoproteins that play a role in vesicle formation and transport. We report the cloning and cDNA sequencing of PACSIN 3 and the analysis of all three PACSIN isoforms with regard to tissue distribution, ligand binding properties and influence on endocytosis. PACSIN 3 differs from the other family members in having a short proline-rich region and lacking asparagine-proline-phenylalanine motifs. In contrast to the neurospecific PACSIN 1 and the ubiquitously expressed PACSIN 2, PACSIN 3 is mainly detected in lung and muscle tissues. All isoforms potentially oligomerize and bind to dynamin, synaptojanin 1 and N-WASP via their Src homology 3 domains. The PACSIN proteins colocalize with dynamin, but not with clathrin, implying a specific role with a distinct subpopulation of dynamin at defined cellular sites. Transferrin endocytosis is blocked in a dose-dependent manner in cells overexpressing the PACSIN variants, but the inhibitory effect can be abolished by mutating specific amino acid residues in the Src homology 3 domains. These characteristics of the PACSIN protein family suggest a general function in recruitment of the interacting proteins to sites of endocytosis.

    Journal of cell science 2000;113 Pt 24;4511-21

  • The calcineurin-binding protein cain is a negative regulator of synaptic vesicle endocytosis.

    Lai MM, Luo HR, Burnett PE, Hong JJ and Snyder SH

    Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

    During neurotransmitter release, exocytosed neurotransmitter vesicles are recycled by endocytosis, which involves the assembly of a complex of endocytic proteins. Assembly of endocytic proteins into a functional complex depends on their dephosphorylation by calcineurin, a calcium-sensitive protein phosphatase and the inhibitory target of immunosuppressive drugs cyclosporin A and FK506. Cain is a recently identified protein inhibitor of calcineurin. We now provide evidence that cain is a component of the endocytic protein complex. The proline-rich region of cain forms a stable association with the SH3 domain of amphiphysin 1. Using a transferrin uptake assay, we found that overexpression of cain in HEK293 cells blocks endocytosis as potently as expression of a dominant negative dynamin 1 construct. The use of other calcineurin inhibitors such as cyclosporin A and FK506 also blocks endocytosis. Since binding of cain to amphiphysin 1 does not affect amphiphysin's interaction with other endocytic proteins, our results suggest that cain negatively regulates synaptic vesicle endocytosis by inhibiting calcineurin activity, rather than sterically interfering with the assembly of the endocytic protein complex.

    Funded by: NIDA NIH HHS: DA-00074; NIGMS NIH HHS: GM-07309; NIMH NIH HHS: MH-18501

    The Journal of biological chemistry 2000;275;44;34017-20

  • Gag3p, an outer membrane protein required for fission of mitochondrial tubules.

    Fekkes P, Shepard KA and Yaffe MP

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

    Mitochondrial morphology and function depend on MGM1, a Saccharomyces cerevisiae gene encoding a dynamin-like protein of the mitochondrial outer membrane. Here, we show that mitochondrial fragmentation and mitochondrial genome loss caused by lesions in MGM1 are suppressed by three novel mutations, gag1, gag2, and gag3 (for glycerol-adapted growth). Cells with any of the gag mutations displayed aberrant mitochondrial morphology characterized by elongated, unbranched tubes and highly fenestrated structures. Additionally, each of the gag mutations prevented mitochondrial fragmentation caused by loss of the mitochondrial fusion factor, Fzo1p, or by treatment of cells with sodium azide. The gag1 mutation mapped to DNM1 that encodes a dynamin-related protein required for mitochondrial fission. GAG3 encodes a novel WD40-repeat protein previously found to interact with Dnm1p in a two-hybrid assay. Gag3p was localized to mitochondria where it was found to associate as a peripheral protein on the cytosolic face of the outer membrane. This association requires neither the DNM1 nor GAG2 gene products. However, the localization of Dnm1p to the mitochondrial outer membrane is substantially reduced by the gag2 mutation, but unaffected by loss of Gag3p. These results indicate that Gag3p plays a distinct role on the mitochondrial surface to mediate the fission of mitochondrial tubules.

    Funded by: NIGMS NIH HHS: GM44614, R01 GM044614

    The Journal of cell biology 2000;151;2;333-40

  • Specificity of the binding of synapsin I to Src homology 3 domains.

    Onofri F, Giovedi S, Kao HT, Valtorta F, Bongiorno Borbone L, De Camilli P, Greengard P and Benfenati F

    Department of Experimental Medicine, Section of Physiology, University of Genova, Via Benedetto XV 3, I-16132 Genova, Italy.

    Synapsins are synaptic vesicle-associated phosphoproteins involved in synapse formation and regulation of neurotransmitter release. Recently, synapsin I has been found to bind the Src homology 3 (SH3) domains of Grb2 and c-Src. In this work we have analyzed the interactions between synapsins and an array of SH3 domains belonging to proteins involved in signal transduction, cytoskeleton assembly, or endocytosis. The binding of synapsin I was specific for a subset of SH3 domains. The highest binding was observed with SH3 domains of c-Src, phospholipase C-gamma, p85 subunit of phosphatidylinositol 3-kinase, full-length and NH(2)-terminal Grb2, whereas binding was moderate with the SH3 domains of amphiphysins I/II, Crk, alpha-spectrin, and NADPH oxidase factor p47(phox) and negligible with the SH3 domains of p21(ras) GTPase-activating protein and COOH-terminal Grb2. Distinct sites in the proline-rich COOH-terminal region of synapsin I were found to be involved in binding to the various SH3 domains. Synapsin II also interacted with SH3 domains with a partly distinct binding pattern. Phosphorylation of synapsin I in the COOH-terminal region by Ca(2+)/calmodulin-dependent protein kinase II or mitogen-activated protein kinase modulated the binding to the SH3 domains of amphiphysins I/II, Crk, and alpha-spectrin without affecting the high affinity interactions. The SH3-mediated interaction of synapsin I with amphiphysins affected the ability of synapsin I to interact with actin and synaptic vesicles, and pools of synapsin I and amphiphysin I were shown to associate in isolated nerve terminals. The ability to bind multiple SH3 domains further implicates the synapsins in signal transduction and protein-protein interactions at the nerve terminal level.

    Funded by: NIA NIH HHS: AG15072; NIMH NIH HHS: MH39327; Telethon: 1131

    The Journal of biological chemistry 2000;275;38;29857-67

  • Dynamin mediates caveolar sequestration of muscarinic cholinergic receptors and alteration in NO signaling.

    Dessy C, Kelly RA, Balligand JL and Feron O

    Department of Medicine, Unit of Pharmacology and Therapeutics, FATH 53.49, Université Catholique de Louvain, Avenue E.Mounier, 53, B-1200 Brussels, Belgium.

    In cardiac myocytes, agonist binding to muscarinic acetylcholine receptors (mAchRs) leads to the targeting of stimulated receptors to plasmalemmal microdomains termed caveolae. Here, we examined whether this translocation leads to mAchR internalization and alteration in downstream NO signaling. Differential binding of membrane-permeant and -impermeant mAchR radioligands on caveolae-enriched membranes revealed that carbachol stimulation of cardiac myocytes induces sequestration of mAchRs through caveolae fission. GTP but not its non-hydrolyzable analog GTP gamma S drove the further detachment of caveolae from myocyte sarcolemma. Also, incubation of extracts of carbachol-stimulated myocytes with recombinant GTPase dynamin induced mAchR sequestration in budded caveolae, while dominant-negative K44A dynamin inhibited it. These data were confirmed by immunofluorescence microscopy on m2 mAchR-expressing COS cells. Finally, repeated carbachol stimulations of mAchRs co-expressed in COS cells with endothelial nitric oxide synthase (eNOS) and wild-type, but not mutant, dynamin led to a progressive increase in mAchR sequestration and a concurrent stabilization of the inhibitory eNOS-caveolin complex. These findings emphasize the role of caveolae in mAchR trafficking and NO signaling, and suggest that caveolae fission may contribute to G-protein-coupled receptor desensitization.

    The EMBO journal 2000;19;16;4272-80

  • Proteomic analysis of NMDA receptor-adhesion protein signaling complexes.

    Husi H, Ward MA, Choudhary JS, Blackstock WP and Grant SG

    Centre for Genome Research, Centre for Neuroscience, University of Edinburgh, West Mains Road, Edinburgh EH9 3JQ, UK.

    N-methyl-d-aspartate receptors (NMDAR) mediate long-lasting changes in synapse strength via downstream signaling pathways. We report proteomic characterization with mass spectrometry and immunoblotting of NMDAR multiprotein complexes (NRC) isolated from mouse brain. The NRC comprised 77 proteins organized into receptor, adaptor, signaling, cytoskeletal and novel proteins, of which 30 are implicated from binding studies and another 19 participate in NMDAR signaling. NMDAR and metabotropic glutamate receptor subtypes were linked to cadherins and L1 cell-adhesion molecules in complexes lacking AMPA receptors. These neurotransmitter-adhesion receptor complexes were bound to kinases, phosphatases, GTPase-activating proteins and Ras with effectors including MAPK pathway components. Several proteins were encoded by activity-dependent genes. Genetic or pharmacological interference with 15 NRC proteins impairs learning and with 22 proteins alters synaptic plasticity in rodents. Mutations in three human genes (NF1, Rsk-2, L1) are associated with learning impairments, indicating the NRC also participates in human cognition.

    Nature neuroscience 2000;3;7;661-9

  • Phosphorylation of dynamin I on Ser-795 by protein kinase C blocks its association with phospholipids.

    Powell KA, Valova VA, Malladi CS, Jensen ON, Larsen MR and Robinson PJ

    Cell Signalling Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, Sydney, New South Wales 2145, Australia.

    Dynamin I is phosphorylated in nerve terminals exclusively in the cytosolic compartment and in vitro by protein kinase C (PKC). Dephosphorylation is required for synaptic vesicle retrieval, suggesting that its phosphorylation affects its subcellular localization. An in vitro phospholipid binding assay was established that prevents lipid vesiculation and dynamin lipid insertion into the lipid. Dynamin I bound the phospholipid in a concentration-dependent and saturable manner, with an apparent affinity of 230 +/- 51 nM. Optimal binding occurred with mixtures of phosphatidylserine and phosphatidylcholine of 1:3 with little binding to phosphatidylcholine or phosphatidylserine alone. Phospholipid binding was abolished after dynamin I phosphorylation by PKC and was restored after dephosphorylation by calcineurin. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry revealed the phosphorylation site in PKCalpha-phosphorylated dynamin I as a single site at Ser-795, located near a binding site for the SH3 domain of p85, the regulatory subunit of phosphatidylinositol 3-kinase. However, phosphorylation had no effect on dynamin binding to a bacterially expressed p85-SH3 domain. Thus, phosphorylation of dynamin I on Ser-795 prevents its association with phospholipid, providing a basis for the cytosolic localization of the minor pool of phospho-dynamin I that mediates synaptic vesicle retrieval in nerve terminals.

    The Journal of biological chemistry 2000;275;16;11610-7

  • The interaction between EEN and Abi-1, two MLL fusion partners, and synaptojanin and dynamin: implications for leukaemogenesis.

    So CW, So CK, Cheung N, Chew SL, Sham MH and Chan LC

    Department of Pathology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, China.

    The mixed lineage leukaemia gene, MLL (also called HRX, ALL-1) in acute leukaemia is fused to at least 16 identified partner genes that display diverse structural and biochemical properties. Using GST pull down and the yeast two hybrid system, we show that two different MLL fusion partners with SH3 domains, EEN and Abi-1, interact with dynamin and synaptojanin, both of which are involved in endocytosis. Synaptojanin, a member of the inositol phosphatase family that has recently been shown to regulate cell proliferation and survival, is also known to bind to Eps15, the mouse homologue of AF1p, another fusion partner of MLL. Expression studies show that synaptojanin is strongly expressed in bone marrow and immature leukaemic cell lines, very weakly in peripheral blood leukocytes and absent in Raji, a mature B cell line. We found that the SH3 domains of EEN and Abi-1 interact with different proline-rich domains of synaptojanin while the EH domains of Eps15 interact with the NPF motifs of synaptojanin. In vitro competitive binding assays demonstrate that EEN displays stronger binding affinity than Abi-1 and may compete with it for synaptojanin. These findings suggest a potential link between MLL fusion-mediated leukaemogenesis and the inositol-signalling pathway.

    Leukemia 2000;14;4;594-601

  • Trafficking of the HIV coreceptor CXCR4. Role of arrestins and identification of residues in the c-terminal tail that mediate receptor internalization.

    Orsini MJ, Parent JL, Mundell SJ, Marchese A and Benovic JL

    Department of Microbiology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

    The G protein-coupled chemokine receptor CXCR4 serves as the primary coreceptor for entry of T-cell tropic human immunodeficiency virus. CXCR4 undergoes tonic internalization as well as internalization in response to stimulation with phorbol esters and ligand (SDF-1alpha). We investigated the trafficking of this receptor, and we attempted to define the residues of CXCR4 that were critical for receptor internalization. In both COS-1 and HEK-293 cells transiently overexpressing CXCR4, SDF-1alpha and phorbol esters (PMA) promoted rapid internalization of cell surface receptors as assessed by both enzyme-linked immunosorbent assay and immunofluorescence analysis. Expression of GRK2 and/or arrestins promoted modest additional CXCR4 internalization in response to both PMA and SDF. Both PMA- and SDF-mediated CXCR4 internalization was inhibited by coexpression of dominant negative mutants of dynamin-1 and arrestin-3. Arrestin was also recruited to the plasma membrane and appeared to colocalize with internalized receptors in response to SDF but not PMA. We then evaluated the ability of CXCR4 receptors containing mutations of serines and threonines, as well as a dileucine motif, within the C-terminal tail to be internalized and phosphorylated in response to either PMA or SDF-1alpha. This analysis showed that multiple residues within the CXCR4 C-terminal tail appear to mediate both PMA- and SDF-1alpha-mediated receptor internalization. The ability of coexpressed GRK2 and arrestins to promote internalization of the CXCR4 mutants revealed distinct differences between respective mutants and suggested that the integrity of the dileucine motif (Ile-328 and Leu-329) and serines 324, 325, 338, and 339 are critical for receptor internalization.

    Funded by: NIDDK NIH HHS: 5-T32-DK07705; NIGMS NIH HHS: GM47419

    The Journal of biological chemistry 1999;274;43;31076-86

  • Crystal structure of the alpha appendage of AP-2 reveals a recruitment platform for clathrin-coat assembly.

    Traub LM, Downs MA, Westrich JL and Fremont DH

    Department of Internal Medicine, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.

    AP-2 adaptors regulate clathrin-bud formation at the cell surface by recruiting clathrin trimers to the plasma membrane and by selecting certain membrane proteins for inclusion within the developing clathrin-coat structure. These functions are performed by discrete subunits of the adaptor heterotetramer. The carboxyl-terminal appendage of the AP-2 alpha subunit appears to regulate the translocation of several endocytic accessory proteins to the bud site. We have determined the crystal structure of the alpha appendage at 1.4-A resolution by multiwavelength anomalous diffraction phasing. It is composed of two distinct structural modules, a beta-sandwich domain and a mixed alpha-beta platform domain. Structure-based mutagenesis shows that alterations to the molecular surface of a highly conserved region on the platform domain differentially affect associations of the appendage with amphiphysin, eps15, epsin, and AP180, revealing a common protein-binding interface.

    Funded by: NIDDK NIH HHS: DK53249, R01 DK053249

    Proceedings of the National Academy of Sciences of the United States of America 1999;96;16;8907-12

  • 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

  • Splice variants of intersectin are components of the endocytic machinery in neurons and nonneuronal cells.

    Hussain NK, Yamabhai M, Ramjaun AR, Guy AM, Baranes D, O'Bryan JP, Der CJ, Kay BK and McPherson PS

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

    We recently identified and cloned intersectin, a protein containing two Eps15 homology (EH) domains and five Src homology 3 (SH3) domains. Using a newly developed intersectin antibody, we demonstrate that endogenous COS-7 cell intersectin localizes to clathrin-coated pits, and transfection studies suggest that the EH domains may direct this localization. Through alternative splicing in a stop codon, a long form of intersectin is generated with a C-terminal extension containing Dbl homology (DH), pleckstrin homology (PH), and C2 domains. Western blots reveal that the long form of intersectin is expressed specifically in neurons, whereas the short isoform is expressed at lower levels in glia and other nonneuronal cells. Immunofluorescence analysis of cultured hippocampal neurons reveals that intersectin is found at the plasma membrane where it is co-localized with clathrin. Ibp2, a protein identified based on its interactions with the EH domains of intersectin, binds to clathrin through the N terminus of the heavy chain, suggesting a mechanism for the localization of intersectin at clathrin-coated pits. Ibp2 also binds to the clathrin adaptor AP2, and antibodies against intersectin co-immunoprecipitate clathrin, AP2, and dynamin from brain extracts. These data suggest that the long and short forms of intersectin are components of the endocytic machinery in neurons and nonneuronal cells.

    The Journal of biological chemistry 1999;274;22;15671-7

  • Syndapin I, a synaptic dynamin-binding protein that associates with the neural Wiskott-Aldrich syndrome protein.

    Qualmann B, Roos J, DiGregorio PJ and Kelly RB

    Department of Biochemistry and Biophysics and the Hormone Research Institute, University of California, San Francisco, California 94143-0534, USA.

    The GTPase dynamin has been clearly implicated in clathrin-mediated endocytosis of synaptic vesicle membranes at the presynaptic nerve terminal. Here we describe a novel 52-kDa protein in rat brain that binds the proline-rich C terminus of dynamin. Syndapin I (synaptic, dynamin-associated protein I) is highly enriched in brain where it exists in a high molecular weight complex. Syndapin I can be involved in multiple protein-protein interactions via a src homology 3 (SH3) domain at the C terminus and two predicted coiled-coil stretches. Coprecipitation studies and blot overlay analyses revealed that syndapin I binds the brain-specific proteins dynamin I, synaptojanin, and synapsin I via an SH3 domain-specific interaction. Coimmunoprecipitation of dynamin I with antibodies recognizing syndapin I and colocalization of syndapin I with dynamin I at vesicular structures in primary neurons indicate that syndapin I associates with dynamin I in vivo and may play a role in synaptic vesicle endocytosis. Furthermore, syndapin I associates with the neural Wiskott-Aldrich syndrome protein, an actin-depolymerizing protein that regulates cytoskeletal rearrangement. These characteristics of syndapin I suggest a molecular link between cytoskeletal dynamics and synaptic vesicle recycling in the nerve terminal.

    Funded by: NIDA NIH HHS: DA-10154, P01 DA010154; NINDS NIH HHS: NS-09878, NS-15927, R01 NS015927

    Molecular biology of the cell 1999;10;2;501-13

  • Src-mediated tyrosine phosphorylation of dynamin is required for beta2-adrenergic receptor internalization and mitogen-activated protein kinase signaling.

    Ahn S, Maudsley S, Luttrell LM, Lefkowitz RJ and Daaka Y

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

    Some forms of G protein-coupled receptor signaling, such as activation of mitogen-activated protein kinase cascade as well as resensitization of receptors after hormone-induced desensitization, require receptor internalization via dynamin-dependent clathrin-coated pit mechanisms. Here we demonstrate that activation of beta2-adrenergic receptors (beta2-ARs) leads to c-Src-mediated tyrosine phosphorylation of dynamin, which is required for receptor internalization. Two tyrosine residues, Tyr231 and Tyr597, are identified as the major phosphorylation sites. Mutation of these residues to phenylalanine dramatically decreases the c-Src-mediated phosphorylation of dynamin following beta2-AR stimulation. Moreover, expression of Y231F/Y597F dynamin inhibits beta2-AR internalization and the isoproterenol-stimulated mitogen-activated protein kinase activation. Thus, agonist-induced, c-Src-mediated tyrosine phosphorylation of dynamin is essential for its function in clathrin mediated G protein-coupled receptor endocytosis.

    Funded by: NHLBI NIH HHS: HL16037

    The Journal of biological chemistry 1999;274;3;1185-8

  • Characterization of interactions of Nck with Sos and dynamin.

    Wunderlich L, Faragó A and Buday L

    Department of Medical Chemistry, Semmelweis University Medical School, Budapest, Hungary.

    One of the adaptor proteins, Nck, comprises a single SH2 domain and three SH3 domains that are important in protein-protein interactions. The in vivo association of Nck with the guanine nucleotide exchange factor Sos has been well documented; however, the precise nature of the interaction is unclear. To determine which SH3 domains are involved in the Nck-Sos interaction, individual SH3 domains of Nck were generated as glutathione S-transferase fusion proteins. We found that exclusively the third (C-terminal) SH3 domain of Nck has the ability to bind to Sos. In addition, in [35S]methionine labelled K562 cells, a 100,000 Mr protein was found to be associated with the third SH3 domain of Nck. This protein was identified as dynamin, a GTP-binding protein that has been implicated in clathrin-coated vesicle formation. Dynamin and Nck co-precipitated when cell lysates were immunoprecipitated with anti-Nck antibody. These data suggest that Nck may contribute to Ras activation and the function of dynamin in membrane trafficking through its third SH3 domain.

    Cellular signalling 1999;11;1;25-9

  • Mixed-lineage kinase 2-SH3 domain binds dynamin and greatly enhances activation of GTPase by phospholipid.

    Rasmussen RK, Rusak J, Price G, Robinson PJ, Simpson RJ and Dorow DS

    Trescowthick Research Centre, Peter MacCallum Cancer Institute, Locked Bag #1 A'Beckett Street, Melbourne, Victoria 3000, Australia.

    Mixed-lineage kinase 2 (MLK2) is a cytoplasmic protein kinase expressed at high levels in mammalian brain. The MLK2 structure is composed of a Src homology 3 (SH3) domain, two leucine zippers, a basic motif, a Cdc42/Rac interactive binding motif and a large C-terminal domain rich in proline, serine and threonine residues. To begin to define the role of MLK2 in mammalian brain, we used an MLK2-SH3 domain-glutathione S-transferase fusion protein (GST-MLK2-SH3) to isolate MLK2-binding proteins from rat brain extract. This analysis revealed that the major MLK2-SH3-domain-binding protein in rat brain is the GTPase dynamin. By using two different forms of the dynamin proline-rich domain as affinity ligands, the binding site for MLK2-SH3 was mapped to the C-terminal region of dynamin between residues 832 and 864. In GTPase assays, the addition of MLK2-SH3 stimulated the activity of purified dynamin I by 3-fold over the basal level, whereas the addition of a known dynamin activator, phosphatidylserine (PtdSer), stimulated a 6-fold increase. When MLK2-SH3 was added to the assay together with PtdSer, however, dynamin GTPase activity accelerated by more than 23-fold over basal level. An MLK2 mutant (MLK2-W59A-SH3), with alanine replacing a conserved tryptophan residue in the SH3 domain consensus motif, had no effect on dynamin activity, either alone or in the presence of PtdSer. In the same assay the SH3 domain from the regulatory subunit of phosphatidylinositol 3'-kinase stimulated a similar synergistic acceleration of dynamin GTPase activity in the presence of PtdSer. These results suggest that synergy between phospholipid and SH3 domain binding might be a general mechanism for the regulation of GTP hydrolysis by dynamin.

    The Biochemical journal 1998;335 ( Pt 1);119-24

  • Growth factor-dependent phosphorylation of the actin-binding protein cortactin is mediated by the cytoplasmic tyrosine kinase FER.

    Kim L and Wong TW

    Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.

    Previous characterization of the nonreceptor tyrosine kinase FER identified a tight physical association with the catenin pp120 and led to the suggestion that FER may be involved in cell-cell signaling. To further understand the function of FER, we have continued our analyses of the interaction of FER with pp120 and other proteins. The majority of FER is localized to the cytoplasmic fraction where it forms a complex with the actin-binding protein cortactin. The Src homology 2 sequence of FER is required for directly binding cortactin, and phosphorylation of the FER-cortactin complex is up-regulated in cells treated with peptide growth factors. Using a dominant-negative mutant of FER, we provided evidence that FER kinase activity is required for the growth factor-dependent phosphorylation of cortactin. These data suggest that cortactin is likely to be a direct substrate of FER. Our observations provide additional support for a role of FER in mediating signaling from the cell surface, via growth factor receptors, to the cytoskeleton. The nature of the FER-cortactin interaction, and their putative enzyme-substrate relationship, support the previous proposal that one of the functions of the Src homology 2 sequences of nonreceptor tyrosine kinases is to provide a binding site for their preferred substrates.

    The Journal of biological chemistry 1998;273;36;23542-8

  • Role of phosphorylation in regulation of the assembly of endocytic coat complexes.

    Slepnev VI, Ochoa GC, Butler MH, Grabs D and De Camilli P

    Howard Hughes Medical Institute and Department of Cell Biology, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA.

    Clathrin-mediated endocytosis involves cycles of assembly and disassembly of clathrin coat components and their accessory proteins. Dephosphorylation of rat brain extract was shown to promote the assembly of dynamin 1, synaptojanin 1, and amphiphysin into complexes that also included clathrin and AP-2. Phosphorylation of dynamin 1 and synaptojanin 1 inhibited their binding to amphiphysin, whereas phosphorylation of amphiphysin inhibited its binding to AP-2 and clathrin. Thus, phosphorylation regulates the association and dissociation cycle of the clathrin-based endocytic machinery, and calcium-dependent dephosphorylation of endocytic proteins could prepare nerve terminals for a burst of endocytosis.

    Funded by: NCI NIH HHS: CA46128; NINDS NIH HHS: NS36251

    Science (New York, N.Y.) 1998;281;5378;821-4

  • In mouse brain profilin I and profilin II associate with regulators of the endocytic pathway and actin assembly.

    Witke W, Podtelejnikov AV, Di Nardo A, Sutherland JD, Gurniak CB, Dotti C and Mann M

    Mouse Biology Programme, EMBL, Monterotondo/Rome, Italy. witke@embl-heidelberg.de

    Profilins are thought to be essential for regulation of actin assembly. However, the functions of profilins in mammalian tissues are not well understood. In mice profilin I is expressed ubiquitously while profilin II is expressed at high levels only in brain. In extracts from mouse brain, profilin I and profilin II can form complexes with regulators of endocytosis, synaptic vesicle recycling and actin assembly. Using mass spectrometry and database searching we characterized a number of ligands for profilin I and profilin II from mouse brain extracts including dynamin I, clathrin, synapsin, Rho-associated coiled-coil kinase, the Rac-associated protein NAP1 and a member of the NSF/sec18 family. In vivo, profilins co-localize with dynamin I and synapsin in axonal and dendritic processes. Our findings strongly suggest that in brain profilin I and profilin II complexes link the actin cytoskeleton and endocytic membrane flow, directing actin and clathrin assembly to distinct membrane domains.

    The EMBO journal 1998;17;4;967-76

  • Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library.

    Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A and Sugano S

    International and Interdisciplinary Studies, The University of Tokyo, Japan.

    Using 'oligo-capped' mRNA [Maruyama, K., Sugano, S., 1994. Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides. Gene 138, 171-174], whose cap structure was replaced by a synthetic oligonucleotide, we constructed two types of cDNA library. One is a 'full length-enriched cDNA library' which has a high content of full-length cDNA clones and the other is a '5'-end-enriched cDNA library', which has a high content of cDNA clones with their mRNA start sites. The 5'-end-enriched library was constructed especially for isolating the mRNA start sites of long mRNAs. In order to characterize these libraries, we performed one-pass sequencing of randomly selected cDNA clones from both libraries (84 clones for the full length-enriched cDNA library and 159 clones for the 5'-end-enriched cDNA library). The cDNA clones of the polypeptide chain elongation factor 1 alpha were most frequently (nine clones) isolated, and more than 80% of them (eight clones) contained the mRNA start site of the gene. Furthermore, about 80% of the cDNA clones of both libraries whose sequence matched with known genes had the known 5' ends or sequences upstream of the known 5' ends (28 out of 35 for the full length-enriched library and 51 out of 62 for the 5'-end-enriched library). The longest full-length clone of the full length-enriched cDNA library was about 3300 bp (among 28 clones). In contrast, seven clones (out of the 51 clones with the mRNA start sites) from the 5'-end-enriched cDNA library came from mRNAs whose length is more than 3500 bp. These cDNA libraries may be useful for generating 5' ESTs with the information of the mRNA start sites that are now scarce in the EST database.

    Gene 1997;200;1-2;149-56

  • Synaptojanin forms two separate complexes in the nerve terminal. Interactions with endophilin and amphiphysin.

    Micheva KD, Kay BK and McPherson PS

    Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 Rue University, Montreal, Quebec H3A 2B4, Canada.

    Endophilin is a recently discovered src homology 3 domain-containing protein that is a major in vitro binding partner for synaptojanin. To further characterize endophilin, we generated an antipeptide antibody. Endophilin is enriched in the brain, and immunofluorescence analysis reveals a high concentration of the protein in synaptic terminals, where it colocalizes with synaptojanin. In vitro binding assays demonstrate that endophilin binds through its src homology 3 domain to synaptojanin, and immunoprecipitation analysis with the antiendophilin antibody reveals that endophilin is stably associated with synaptojanin in the nerve terminal. Immunoprecipitation with an antibody against amphiphysin I and II, which interact through their src homology 3 domains with dynamin and synaptojanin at sites distinct from those for endophilin, reveals a second stable complex, which includes dynamin and synaptojanin but excludes endophilin. These data demonstrate that synaptojanin is present in two separate complexes in the nerve terminal and support an important role for endophilin in the regulation of synaptojanin function.

    The Journal of biological chemistry 1997;272;43;27239-45

  • Amphiphysin heterodimers: potential role in clathrin-mediated endocytosis.

    Wigge P, Köhler K, Vallis Y, Doyle CA, Owen D, Hunt SP and McMahon HT

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

    Amphiphysin (Amph) is a src homology 3 domain-containing protein that has been implicated in synaptic vesicle endocytosis as a result of its interaction with dynamin. In a screen for novel members of the amphiphysin family, we identified Amph2, an isoform 49% identical to the previously characterized Amph1 protein. The subcellular distribution of this isoform parallels Amph1, both being enriched in nerve terminals. Like Amph1, a role in endocytosis at the nerve terminal is supported by the rapid dephosphorylation of Amph2 on depolarization. Importantly, the two isoforms can be coimmunoprecipitated from the brain as an equimolar complex, suggesting that the two isoforms act in concert. As determined by cross-linking of brain extracts, the Amph1-Amph2 complex is a 220- to 250-kDa heterodimer. COS cells transfected with either Amph1 or Amph2 show greatly reduced transferrin uptake, but coexpression of the two proteins rescues this defect, supporting a role for the heterodimer in clathrin-mediated endocytosis. Although the src homology 3 domains of both isoforms interact with dynamin, the heterodimer can associate with multiple dynamin molecules in vitro and activates dynamin's GTPase activity. We propose that it is an amphiphysin heterodimer that drives the recruitment of dynamin to clathrin-coated pits in endocytosing nerve terminals.

    Molecular biology of the cell 1997;8;10;2003-15

  • Clathrin interacts specifically with amphiphysin and is displaced by dynamin.

    McMahon HT, Wigge P and Smith C

    Neurobiology Division, MRC-LMB, Cambridge, UK. hmm@mrc-lmb.cam.ac.uk

    Amphiphysin is an SH3 domain protein that has been implicated in synaptic vesicle endocytosis. We have recently cloned a second amphiphysin isoform, Amph2 (sequence submitted to GenBank, Y13380). Proteins capable of forming a complex with amphiphysin were isolated from rat brain by using recombinant GST-Amph2 for binding experiments. As well as interacting with dynamin I, the full-length protein bound to a weaker 180-kDa band. Immunoblotting demonstrated this protein to be clathrin. To address whether this is a direct interaction, the clathrin binding to amphiphysin was reconstituted in vitro with purified proteins. The N-terminal domain of Amph2 is sufficient for clathrin binding. Dynamin, which interacts with the SH3 domain of Amph2, displaces clathrin from the N-terminus. We propose a model that may explain how clathrin and dynamin are recruited to non-overlapping sites of the coated pit.

    FEBS letters 1997;413;2;319-22

  • The SH3p4/Sh3p8/SH3p13 protein family: binding partners for synaptojanin and dynamin via a Grb2-like Src homology 3 domain.

    Ringstad N, Nemoto Y and De Camilli P

    Department of Cell Biology and Howard Hughes Medical Institute, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA.

    The GTPase dynamin I and the inositol 5-phosphatase synaptojanin are nerve terminal proteins implicated in synaptic vesicle recycling. Both proteins contain COOH-terminal proline-rich domains that can interact with a variety of Src homology 3 (SH3) domains. A major physiological binding partner for dynamin I and synaptojanin in the nervous system is amphiphysin I, an SH3 domain-containing protein also concentrated in nerve terminals. We have used the proline-rich tail of synaptojanin to screen a rat brain library by the two-hybrid method to identify additional interacting partners of synaptojanin. Three related proteins containing SH3 domains that are closely related to the SH3 domains of Grb2 were isolated: SH3p4, SH3p8, and SH3p13. Further biochemical studies demonstrated that the SH3p4/8/13 proteins bind to both synaptojanin and dynamin I. The SH3p4/8/13 transcripts are differentially expressed in tissues: SH3p4 mRNA was detected only in brain, SH3p13 mRNA was present in brain and testis, and the SH3p8 transcript was detected at similar levels in multiple tissues. Members of the SH3p4/8/13 protein family were found to be concentrated in nerve terminals, and pools of synaptojanin and dynamin I were coprecipitated from brain extracts with antibodies recognizing SH3p4/8/13. These findings underscore the important role of SH3-mediated interactions in synaptic vesicle recycling.

    Funded by: NCI NIH HHS: CA48128; NIGMS NIH HHS: 5-T32GM07527-20, T32 GM007527

    Proceedings of the National Academy of Sciences of the United States of America 1997;94;16;8569-74

  • Identification and characterization of a nerve terminal-enriched amphiphysin isoform.

    Ramjaun AR, Micheva KD, Bouchelet I and McPherson PS

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

    Amphiphysin is a nerve terminal-enriched protein thought to function in synaptic vesicle endocytosis, in part through Src homology 3 (SH3) domain-mediated interactions with dynamin and synaptojanin. Here, we report the characterization of a novel amphiphysin isoform (termed amphiphysin II) that was identified through a homology search of the data base of expressed sequence tags. Antibodies specific to amphiphysin II recognize a 90-kDa protein on Western blot that is brain-specific and highly enriched in nerve terminals. Like amphiphysin (now referred to as amphiphysin I), amphiphysin II binds to dynamin and synaptojanin through its SH3 domain. Further, both proteins bind directly to clathrin in an SH3 domain-independent manner. Taken together, these data suggest that amphiphysin II may participate with amphiphysin I in the regulation of synaptic vesicle endocytosis.

    The Journal of biological chemistry 1997;272;26;16700-6

  • The SH3 domain of amphiphysin binds the proline-rich domain of dynamin at a single site that defines a new SH3 binding consensus sequence.

    Grabs D, Slepnev VI, Songyang Z, David C, Lynch M, Cantley LC and De Camilli P

    Department of Cell Biology and Howard Hughes Medical Institute, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, Connecticut 06510, USA.

    Amphiphysin is an SH3 domain-containing neuronal protein that is highly concentrated in nerve terminals where it interacts via its SH3 domain with dynamin I, a GTPase implicated in synaptic vesicle endocytosis. We show here that the SH3 domain of amphiphysin, but not a mutant SH3 domain, bound with high affinity to a single site in the long proline-rich region of human dynamin I, that this site was distinct from the binding sites for other SH3 domains, and that the mutation of two adjacent amino acids in dynamin I was sufficient to abolish binding. The dynamin I sequence critically required for amphiphysin binding (PSRPNR) fits in the novel SH3 binding consensus identified for the SH3 domain of amphiphysin via a combinatorial peptide library approach: PXRPXR(H)R(H). Our data demonstrate that the long proline-rich stretch present in dynamin I contained multiple SH3 domain binding sites that recognize interacting proteins with high specificity.

    Funded by: NIGMS NIH HHS: R01 GM056203

    The Journal of biological chemistry 1997;272;20;13419-25

  • Assignment of the dynamin-1 gene (DNM1) to human chromosome 9q34 by fluorescence in situ hybridization and somatic cell hybrid analysis.

    Newman-Smith ED, Shurland DL and van der Bliek AM

    Department of Biological Chemistry, University of California at Los Angeles School of Medicine 90095-1737, USA.

    The dynamins are recently discovered GTP-binding proteins postulated to mediate the scission of clathrin-coated vesicles at the plasma membrane. Of the three known mammalian dynamins, dynamin-1 (DNM1) appears to be particularly important for the formation of synaptic vesicles at presynaptic nerve termini. To investigate the possibility that mutations in the DNM1 gene cause a human disease, we determined the chromosomal localization of human DNM1. We conclude from fluorescence in situ hybridization and from the analysis of somatic cell hybrids that the map position in 9q34. This region has syntenic homology with mouse chromosome 2p, in agreement with the map position of the mouse DNM1 gene [see accompanying article by Klocke et al. (1997, Genomics 41:290-292)]. We discuss the potential relevance of the human DNM1 localization to diseases that were mapped genetically to the same chromosomal region.

    Funded by: NIGMS NIH HHS: GM51866

    Genomics 1997;41;2;286-9

  • Multiple Grb2-protein complexes in human cancer cells.

    Sastry L, Cao T and King CR

    Department of Biochemistry, Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007. USA.

    Grb2 is an SH2/SH3 domain-containing adaptor protein that links receptor tyrosine kinases to the ras signaling pathway. The Grb2-SH2 domain binds phosphotyrosine sequences on activated tyrosine kinases, and one target of the SH3 domains is the ras-nucleotide-exchange factor Sos1. We have examined Grb2-protein interactions in human cancer cells that over-express the receptor tyrosine kinase erbB2. Our results show that the 2 Grb2-SH3 domains complex with Sos1, dynamin and at least 4 other proteins (p228, p140, p55, p28) in these cells. The 2 Grb2-SH3 domains bind these proteins differently, with the N-terminal SH3 domain interacting preferentially with p228, Sos1, p140 and dynamin. The C-terminal SH3 domain has higher affinity toward p28. The Grb2-SH3 domain interactions appear to be similar in erbB2 over-expressing breast, ovarian and lung cancer cells. Also, the major tyrosine-phosphorylated proteins that associate with Grb2 in erbB2 over-expressing cancer cells appear to be erbB2 and Shc. The multiple Grb2-SH3 domain interactions in these cells may mediate novel cellular functions.

    International journal of cancer 1997;70;2;208-13

  • Crystal structure of the pleckstrin homology domain from dynamin.

    Timm D, Salim K, Gout I, Guruprasad L, Waterfield M and Blundell T

    Department of Crystallography, Birkbeck College, London, UK.

    The pleckstrin homology (PH) domain is a conserved module present in many signal transducing and cytoskeletal proteins. Here we report the 2.8 A crystal structure of the PH domain from dynamin. This domain consists of seven beta-strands forming two roughly orthogonal antiparallel beta-sheets terminating with an amphipathic alpha-helix. The structure also reveals a non-covalent dimeric association of the PH domain and a hydrophobic pocket surrounded by a charged rim. The dynamin PH domain structure is discussed in relation to its potential role in mediating interactions between proteins.

    Nature structural biology 1994;1;11;782-8

  • Crystal structure at 2.2 A resolution of the pleckstrin homology domain from human dynamin.

    Ferguson KM, Lemmon MA, Schlessinger J and Sigler PB

    Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06510.

    The X-ray crystal structure of the pleckstrin homology (PH) domain from human dynamin has been refined to 2.2 A resolution. A seven-stranded beta sandwich of two orthogonal antiparallel beta sheets is closed at one corner by a C-terminal alpha helix. Opposite this helix are the three loops that vary most among PH domains. The basic fold is very similar to that of two other PH domains recently determined by nuclear magnetic resonance, confirming that PH domain with known structure is electrostatically polarized, with the three variable loops forming a positively charged surface. This surface includes the position of the X-linked immunodeficiency mutation in the Btk PH domain and may serve as a ligand-binding surface.

    Funded by: NIGMS NIH HHS: GM15225, GM22324

    Cell 1994;79;2;199-209

  • Three-dimensional solution structure of the pleckstrin homology domain from dynamin.

    Downing AK, Driscoll PC, Gout I, Salim K, Zvelebil MJ and Waterfield MD

    Oxford University, Department of Biochemistry, UK.

    Background: The pleckstrin homology (PH) domain is a region of approximately 100 amino acids, defined by sequence similarity, that has been found in about 60 proteins, many of which are involved in signal transduction downstream of cell surface receptors; the function of PH domains is unknown. The only clue to the function of PH domains is the circumstantial evidence that they may link beta gamma subunits of G proteins to second messenger systems. Knowledge of the three-dimensional structures of PH domains should help to elucidate the roles they play in the proteins that contain them.

    Results: Using homonuclear and heteronuclear magnetic resonance spectroscopy, we have determined the solution structure of the PH domain of the GTPase dynamin, one of a number of proteins that have PH domains and interact with GTP. The fold of the dynamin PH domain is composed of two antiparallel beta-sheets, which pack face-to-face at an angle of approximately 60 degrees. The first beta-sheet comprises four strands (residues 13-58) from the amino-terminal half of the protein sequence; the second beta-sheet contains three strands (residues 63-99). A single alpha-helix (residues 102-116) flanks one edge of the interface between the two sheets, parallel in orientation to the second sheet, in an alpha/beta roll motif similar to that of the B oligomer of verotoxin-1 from Escherichia coli.

    Conclusions: The structure of the dynamin PH domain is very similar to the recently reported structures of the pleckstrin and spectrin PH domains. This shows that, despite the low level of sequence similarity between different PH domains, they do have a characteristic polypeptide fold. On the basis of our structure, the suggestion that PH domains engage in coiled-coil interactions with G protein beta gamma subunits seems unlikely and should be re-evaluated.

    Current biology : CB 1994;4;10;884-91

  • Association of Ash/Grb-2 with dynamin through the Src homology 3 domain.

    Miki H, Miura K, Matuoka K, Nakata T, Hirokawa N, Orita S, Kaibuchi K, Takai Y and Takenawa T

    Department of Molecular Oncology, University of Tokyo, Japan.

    Ash/Grb-2 is an adaptor protein composed only of Src homology (SH) 2 and SH3 domains that is considered to be essential for Ras activation. To clarify the downstream of Ash signaling, we investigated Ash-bound proteins. Ash-glutathione S-transferase (GST) fusion proteins were used to affinity-purify proteins bound to Ash. We found 180-, 150-, 100-, and 70-kDa proteins bound to GST-Ash, among which the 100 kDa protein was found to be dynamin by amino acid sequencing and Western blot with anti-dynamin antibody. Next, the in vitro and in vivo associations between Ash and dynamin were examined using PC12 cells. Dynamin in PC12 cell lysates bound to GST-Ash independent of NGF treatment. Also, Ash and dynamin co-precipitated when cell lysates of PC12 were immunoprecipitated with anti-Ash antibody or anti-dynamin antibody. Using various GST-Ash constructs, we studied the importance of the individual domains in binding and found that the SH3 domain is necessary for binding. This binding was inhibited by a synthetic peptide (GPPQVPSRPNRC, amino acids 827-838 in dynamin). These data show that Ash SH3 domains bind to the proline-rich region of dynamin. Considering the function of dynamin in membrane trafficking, Ash may regulate endocytosis in addition to Ras activation.

    The Journal of biological chemistry 1994;269;8;5489-92

  • Differential expression and regulation of multiple dynamins.

    Sontag JM, Fykse EM, Ushkaryov Y, Liu JP, Robinson PJ and Südhof TC

    Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

    Dynamin is a GTP-, microtubule-, and phospholipid-binding protein that is expressed primarily in brain. In Drosophila, the shibire gene encodes a homologue of dynamin; mutations in this gene result in a defect in endocytosis, suggesting a function for dynamin in endocytic membrane traffic. In the present study we show that there are at least two distinct dynamin genes in mammals whose products are referred to as dynamins I and II. The two dynamins are similar to each other (79% identity) and are both equally homologous to the Drosophila shibire gene product (66% identity). The highest degree of identity between dynamins is observed in their N-terminal halves, whereas their C termini exhibit little homology. Transcripts of both dynamin genes are subject to at least two alternative splicing events, the first of which is identically found in both dynamins, whereas the second site of alternative splicing is different between the two types of dynamins. The first alternatively spliced sequence of the dynamins consists of an interior region that is present in two distinct but homologous forms in both dynamins, suggesting alternative use of exons in both genes at identical positions. The second site of alternative splicing results in the generation of different C termini in dynamin I and in the inclusion or exclusion of an interior four-amino acid sequence in dynamin II. The two dynamins exhibit remarkable differences in their tissue distribution and regulation. Dynamin I is almost exclusively expressed in the central nervous system. Conversely, dynamin II is expressed ubiquitously in all tissues tested. Previous studies revealed that the GTPase activity of dynamin I is regulated by phosphorylation by protein kinase C in nerve terminals. Expression of dynamins I and II by transfection in COS cells demonstrates that only dynamin I but not dynamin II is a substrate for protein kinase C. Our data suggest a specialization in the endocytic functions and the regulation of dynamins between neural and non-neural tissues in mammals.

    The Journal of biological chemistry 1994;269;6;4547-54

  • Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides.

    Maruyama K and Sugano S

    Institute of Medical Science, University of Tokyo, Japan.

    We have devised a method to replace the cap structure of a mRNA with an oligoribonucleotide (r-oligo) to label the 5' end of eukaryotic mRNAs. The method consists of removing the cap with tobacco acid pyrophosphatase (TAP) and ligating r-oligos to decapped mRNAs with T4 RNA ligase. This reaction was made cap-specific by removing 5'-phosphates of non-capped RNAs with alkaline phosphatase prior to TAP treatment. Unlike the conventional methods that label the 5' end of cDNAs, this method specifically labels the capped end of the mRNAs with a synthetic r-oligo prior to first-strand cDNA synthesis. The 5' end of the mRNA was identified quite simply by reverse transcription-polymerase chain reaction (RT-PCR).

    Gene 1994;138;1-2;171-4

  • Mutations in human dynamin block an intermediate stage in coated vesicle formation.

    van der Bliek AM, Redelmeier TE, Damke H, Tisdale EJ, Meyerowitz EM and Schmid SL

    Division of Biology, California Institute of Technology, Pasadena 91125.

    The role of human dynamin in receptor-mediated endocytosis was investigated by transient expression of GTP-binding domain mutants in mammalian cells. Using assays which detect intermediates in coated vesicle formation, the dynamin mutants were found to block endocytosis at a stage after the initiation of coat assembly and preceding the sequestration of ligands into deeply invaginated coated pits. Membrane transport from the ER to the Golgi complex was unaffected indicating that dynamin mutants specifically block early events in endocytosis. These results demonstrate that mutations in the GTP-binding domain of dynamin block Tfn-endocytosis in mammalian cells and suggest that a functional dynamin GTPase is required for receptor-mediated endocytosis via clathrin-coated pits.

    Funded by: NCI NIH HHS: CA09270; NIGMS NIH HHS: GM40499, GM42445

    The Journal of cell biology 1993;122;3;553-63

  • Molecular cloning of the microtubule-associated mechanochemical enzyme dynamin reveals homology with a new family of GTP-binding proteins.

    Obar RA, Collins CA, Hammarback JA, Shpetner HS and Vallee RB

    Cell Biology Group, Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545.

    A complementary DNA encoding the D100 polypeptide of rat brain dynamin--a force-producing, microtubule-activated nucleotide triphosphatase--has been cloned and sequenced. The predicted amino acid sequence includes a guanine nucleotide-binding domain that is homologous with those of a family of antiviral factors, inducible by interferon and known as Mx proteins, and with the product of the essential yeast vacuolar protein sorting gene VPS1. These relationships imply the existence of a new family of GTPases with physiological roles that may include microtubule-based motility and protein sorting.

    Nature 1990;347;6290;256-61

Gene lists (11)

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
L00000011 G2C Homo sapiens Human clathrin Human orthologues of mouse clathrin coated vesicle genes adapted from Collins et al (2006) 150
L00000012 G2C Homo sapiens Human Synaptosome Human orthologues of mouse synaptosome adapted from Collins et al (2006) 152
L00000013 G2C Homo sapiens Human mGluR5 Human orthologues of mouse mGluR5 complex adapted from Collins et al (2006) 52
L00000015 G2C Homo sapiens Human NRC Human orthologues of mouse NRC adapted from Collins et al (2006) 186
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000034 G2C Homo sapiens Pocklington H3 Human orthologues of cluster 3 (mouse) from Pocklington et al (2006) 30
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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