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Li L, Liu H, Qian KY, Nurrish S, Zeng XT, Zeng WX, Wang J, Kaplan JM, Tong XJ, Hu Z. CASK and FARP localize two classes of post-synaptic ACh receptors thereby promoting cholinergic transmission. PLoS Genet 2022; 18:e1010211. [PMID: 36279278 PMCID: PMC9632837 DOI: 10.1371/journal.pgen.1010211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 11/03/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
Changes in neurotransmitter receptor abundance at post-synaptic elements play a pivotal role in regulating synaptic strength. For this reason, there is significant interest in identifying and characterizing the scaffolds required for receptor localization at different synapses. Here we analyze the role of two C. elegans post-synaptic scaffolding proteins (LIN-2/CASK and FRM-3/FARP) at cholinergic neuromuscular junctions. Constitutive knockouts or muscle specific inactivation of lin-2 and frm-3 dramatically reduced spontaneous and evoked post-synaptic currents. These synaptic defects resulted from the decreased abundance of two classes of post-synaptic ionotropic acetylcholine receptors (ACR-16/CHRNA7 and levamisole-activated AChRs). LIN-2's AChR scaffolding function is mediated by its SH3 and PDZ domains, which interact with AChRs and FRM-3/FARP, respectively. Thus, our findings show that post-synaptic LIN-2/FRM-3 complexes promote cholinergic synaptic transmission by recruiting AChRs to post-synaptic elements.
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Affiliation(s)
- Lei Li
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
| | - Haowen Liu
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
| | - Kang-Ying Qian
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Stephen Nurrish
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Xian-Ting Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Wan-Xin Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jiafan Wang
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
| | - Joshua M. Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Xia-Jing Tong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Zhitao Hu
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
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Vincenzi M, Mercurio FA, Leone M. Protein Interaction Domains: Structural Features and Drug Discovery Applications (Part 2). Curr Med Chem 2021; 28:854-892. [PMID: 31942846 DOI: 10.2174/0929867327666200114114142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/28/2019] [Accepted: 11/04/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Proteins present a modular organization made up of several domains. Apart from the domains playing catalytic functions, many others are crucial to recruit interactors. The latter domains can be defined as "PIDs" (Protein Interaction Domains) and are responsible for pivotal outcomes in signal transduction and a certain array of normal physiological and disease-related pathways. Targeting such PIDs with small molecules and peptides able to modulate their interaction networks, may represent a valuable route to discover novel therapeutics. OBJECTIVE This work represents a continuation of a very recent review describing PIDs able to recognize post-translationally modified peptide segments. On the contrary, the second part concerns with PIDs that interact with simple peptide sequences provided with standard amino acids. METHODS Crucial structural information on different domain subfamilies and their interactomes was gained by a wide search in different online available databases (including the PDB (Protein Data Bank), the Pfam (Protein family), and the SMART (Simple Modular Architecture Research Tool)). Pubmed was also searched to explore the most recent literature related to the topic. RESULTS AND CONCLUSION PIDs are multifaceted: they have all diverse structural features and can recognize several consensus sequences. PIDs can be linked to different diseases onset and progression, like cancer or viral infections and find applications in the personalized medicine field. Many efforts have been centered on peptide/peptidomimetic inhibitors of PIDs mediated interactions but much more work needs to be conducted to improve drug-likeness and interaction affinities of identified compounds.
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Affiliation(s)
- Marian Vincenzi
- Institute of Biostructures and Bioimaging, National Research Council (CNR), Via Mezzocannone 16, 80134 Naples, Italy
| | - Flavia Anna Mercurio
- Institute of Biostructures and Bioimaging, National Research Council (CNR), Via Mezzocannone 16, 80134 Naples, Italy
| | - Marilisa Leone
- Institute of Biostructures and Bioimaging, National Research Council (CNR), Via Mezzocannone 16, 80134 Naples, Italy
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3
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Using RNA-Seq to Explore the Repair Mechanism of the Three Methods and Three-Acupoint Technique on DRGs in Sciatic Nerve Injured Rats. Pain Res Manag 2020; 2020:7531409. [PMID: 32587647 PMCID: PMC7298348 DOI: 10.1155/2020/7531409] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/31/2020] [Indexed: 12/28/2022]
Abstract
Objective To study the effects of the three methods and three-acupoint technique on DRG gene expression in SNI model rats and to elucidate the molecular mechanism of the three methods and three-acupoint technique on promoting recovery in peripheral nerve injury. Methods 27 male SD rats were randomly divided into three groups: a Sham group, the SNI group, and the Tuina group. The Tuina group was treated with a tuina manipulation simulator to simulate massage on points, controlling for both quality and quantity. Point-pressing, plucking, and kneading methods were administered quantitatively at Yinmen (BL37), Chengshan (BL57), and Yanglingquan (GB34) points on the affected side once a day, beginning 7 days after modeling. Intervention was applied once a day for 10 days, then 1 day of rest, followed by 10 more days of intervention, totally equaling 20 times of intervention. The effect of the three methods and three-point technique on the recovery of injured rats was evaluated using behavior analysis. RNA sequencing (RNA-Seq) analysis of differentially expressed genes in DRGs of the three groups of rats was also performed. GO and KEGG enrichment was analyzed and verified using real-time PCR. Results RNA-Seq combined with database information showed that the number of differentially expressed genes in DRG was the largest in the Tuina group compared with the SNI group, totaling 226. GO function is enriched in the positive regulation of cell processes, ion binding, protein binding, neuron, response to pressure, response to metal ions, neuron projection, and other biological processes. GO function is also enriched in the Wnt, IL-17, and MAPK signaling pathways in the KEGG database. PCR results were consistent with those of RNA sequencing, suggesting that the results of transcriptome sequencing were reliable. Conclusion The three methods and three-acupoint technique can promote the recovery of SNI model rats by altering the gene sequence in DRGs.
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Philippe JM, Jenkins PM. Spatial organization of palmitoyl acyl transferases governs substrate localization and function. Mol Membr Biol 2020; 35:60-75. [PMID: 31969037 DOI: 10.1080/09687688.2019.1710274] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Protein palmitoylation is a critical posttranslational modification that regulates protein trafficking, localization, stability, sorting and function. In mammals, addition of this lipid modification onto proteins is mediated by a family of 23 palmitoyl acyl transferases (PATs). PATs often palmitoylate substrates in a promiscuous manner, precluding our understanding of how these enzymes achieve specificity for their substrates. Despite generous efforts to identify consensus motifs defining PAT-substrate specificity, it remains to be determined whether additional factors beyond interaction motifs, such as local palmitoylation, participate in PAT-substrate selection. In this review, we emphasize the role of local palmitoylation, in which substrates are palmitoylated and trapped in the same subcellular compartments as their PATs, as a mechanism of enzyme-substrate specificity. We focus here on non-Golgi-localized PATs, as physical proximity to their substrates enables them to engage in local palmitoylation, compared to Golgi PATs, which often direct trafficking of their substrates elsewhere. PAT subcellular localization may be an under-recognized, yet important determinant of PAT-substrate specificity that may work in conjunction or completely independently of interaction motifs. We also discuss some current hypotheses about protein motifs that contribute to localization of non-Golgi-localized PATs, important for the downstream targeting of their substrates.
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Affiliation(s)
- Julie M Philippe
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Paul M Jenkins
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Psychiatry, University of Michigan Medical School, Ann Arbor, MI, USA
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5
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Fischetto R, Palumbo O, Ortolani F, Palumbo P, Leone MP, Causio FA, Pesce S, Digilio MC, Carella M, Papadia F. Clinical and molecular characterization of a second family with the 12q14 microdeletion syndrome and review of the literature. Am J Med Genet A 2017; 173:1922-1930. [PMID: 28407409 DOI: 10.1002/ajmg.a.38253] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 03/16/2017] [Indexed: 11/11/2022]
Abstract
The 12q14 microdeletion syndrome is a rare condition characterized by low birth weight, failure to thrive, short stature, learning disabilities, and osteopoikilosis. To date, 20 cases of 12q14 deletion have been reported in the literature, displaying both phenotypic than genetic variability. We report on three familial cases, a mother and two brothers, with severe short stature. The mother and elder brother presented with osteopoikilosis while the younger brother had severe short stature and developmental delay. SNP array analysis revealed a 1.9 Mb heterozygous 12q14.2q14.3 deletion in all three patients encompassing 14 genes and 3 miRNAs. In addition, the younger brother carried a paternal 11q13.4 duplication including the SHANK2 gene. This latter patient was investigated for developmental delay and did not show osteopoikilosis, confirming the role of age in the clinical presentation of this condition. To the best of our knowledge, this is the second family described with the syndrome. Comparing the clinical and molecular data of our patients with those previously reported we performed a detailed genotype-phenotype correlation confirming the association between growth retardation and osteopoikilosis when the rearrangement includes both LEMD3 and HMGA2 genes. In addition, we suggest the XPOT, TBK1, WIF1 genes as candidates for the clinical features observed in our patients and discuss for the first time the possible involvement of some microRNAs, when deleted, in the etiology of the phenotypes in 12q14 microdeletion syndrome patients. We expect the interpretation of our findings to be useful both from a molecular point of view and for genetic counseling.
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Affiliation(s)
- Rita Fischetto
- U.O.C. Malattie Metaboliche Genetica Medica, PO Giovanni XXIII, A.O.U. Policlinico Consorziale, Bari, Italy.,Istituto di Biologia e Genetica Generale, Medicina e Chirurgia, Università degli Studi di Bari "Aldo Moro", Bari, Italy
| | - Orazio Palumbo
- Laboratorio di Genetica Medica, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Federica Ortolani
- U.O.C. Malattie Metaboliche Genetica Medica, PO Giovanni XXIII, A.O.U. Policlinico Consorziale, Bari, Italy
| | - Pietro Palumbo
- Laboratorio di Genetica Medica, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Maria Pia Leone
- Laboratorio di Genetica Medica, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy.,Dipartimento di Scienze del suolo, della pianta e degli alimenti, Università degli Studi di Bari "Aldo Moro", Bari, Italy
| | - Francesco Andrea Causio
- Istituto di Patologia Generale, Facoltà di Medicina e Chirurgia, Università Cattolica Sacro Cuore, Roma, Italy
| | - Sabino Pesce
- U.O.C. Malattie Metaboliche Genetica Medica, PO Giovanni XXIII, A.O.U. Policlinico Consorziale, Bari, Italy
| | | | - Massimo Carella
- Laboratorio di Genetica Medica, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Francesco Papadia
- U.O.C. Malattie Metaboliche Genetica Medica, PO Giovanni XXIII, A.O.U. Policlinico Consorziale, Bari, Italy
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Genome-wide association study (GWAS) for growth rate and age at sexual maturation in Atlantic salmon (Salmo salar). PLoS One 2015; 10:e0119730. [PMID: 25757012 PMCID: PMC4355585 DOI: 10.1371/journal.pone.0119730] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 01/25/2015] [Indexed: 11/26/2022] Open
Abstract
Early sexual maturation is considered a serious drawback for Atlantic salmon aquaculture as it retards growth, increases production times and affects flesh quality. Although both growth and sexual maturation are thought to be complex processes controlled by several genetic and environmental factors, selection for these traits has been continuously accomplished since the beginning of Atlantic salmon selective breeding programs. In this genome-wide association study (GWAS) we used a 6.5K single-nucleotide polymorphism (SNP) array to genotype ∼480 individuals from the Cermaq Canada broodstock program and search for SNPs associated with growth and age at sexual maturation. Using a mixed model approach we identified markers showing a significant association with growth, grilsing (early sexual maturation) and late sexual maturation. The most significant associations were found for grilsing, with markers located in Ssa10, Ssa02, Ssa13, Ssa25 and Ssa12, and for late maturation with markers located in Ssa28, Ssa01 and Ssa21. A lower level of association was detected with growth on Ssa13. Candidate genes, which were linked to these genetic markers, were identified and some of them show a direct relationship with developmental processes, especially for those in association with sexual maturation. However, the relatively low power to detect genetic markers associated with growth (days to 5 kg) in this GWAS indicates the need to use a higher density SNP array in order to overcome the low levels of linkage disequilibrium observed in Atlantic salmon before the information can be incorporated into a selective breeding program.
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Gjørlund MD, Nielsen J, Pankratova S, Li S, Korshunova I, Bock E, Berezin V. Neuroligin-1 induces neurite outgrowth through interaction with neurexin-1β and activation of fibroblast growth factor receptor-1. FASEB J 2012; 26:4174-86. [PMID: 22750515 DOI: 10.1096/fj.11-202242] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Neurexin-1 (NRXN1) and neuroligin-1 (NLGN1) are synaptic cell adhesion molecules that connect pre- and postsynaptic neurons at synapses and mediate signaling across the synapse, which modulates synaptic activity and determines the properties of neuronal networks. Defects in the genes encoding NLGN1 have been linked to cognitive diseases such as autism. The roles of both NRXN1 and NLGN1 during synaptogenesis have been studied extensively, but little is known about the role of these molecules in neuritogenesis, which eventually results in neuronal circuitry formation. The present study investigated the neuritogenic effect of NLGN1 in cultures of hippocampal neurons. Our results show that NLGN1, both in soluble and membrane-bound forms, induces neurite outgrowth that depends on the interaction with NRXN1β and on activation of fibroblast growth factor receptor-1. In addition, we demonstrate that a synthetic peptide, termed neurolide, which is modeled after a part of the binding interface of NLGN1 for NRXN1β, can bind to NRXN1β and mimic the biological properties of NLGN1 in vitro.
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Affiliation(s)
- Michelle D Gjørlund
- Protein Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, Building 24.2, DK-2200 Copenhagen, Denmark
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8
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Momboisse F, Houy S, Ory S, Calco V, Bader MF, Gasman S. How important are Rho GTPases in neurosecretion? J Neurochem 2011; 117:623-31. [PMID: 21392006 DOI: 10.1111/j.1471-4159.2011.07241.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Rho GTPases are small GTP binding proteins belonging to the Ras superfamily which act as molecular switches that regulate many cellular function including cell morphology, cell to cell interaction, cell migration and adhesion. In neuronal cells, Rho GTPases have been proposed to regulate neuronal development and synaptic plasticity. However, the role of Rho GTPases in neurosecretion is poorly documented. In this review, we discuss data that highlight the importance of Rho GTPases and their regulators into the control of neurotransmitter and hormone release in neurons and neuroendocrine cells, respectively.
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Affiliation(s)
- Fanny Momboisse
- CNRS UPR 3212, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
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9
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Ivanova S, Gregorc U, Vidergar N, Javier R, Bredt DS, Vandenabeele P, Pardo J, Simon MM, Turk V, Banks L, Turk B. MAGUKs, scaffolding proteins at cell junctions, are substrates of different proteases during apoptosis. Cell Death Dis 2011; 2:e116. [PMID: 21368887 PMCID: PMC3077288 DOI: 10.1038/cddis.2010.92] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A major feature of apoptotic cell death is gross structural changes, one of which is the loss of cell–cell contacts. The caspases, executioners of apoptosis, were shown to cleave several proteins involved in the formation of cell junctions. The membrane-associated guanylate kinases (MAGUKs), which are typically associated with cell junctions, have a major role in the organization of protein–protein complexes at plasma membranes and are therefore potentially important caspase targets during apoptosis. We report here that MAGUKs are cleaved and/or degraded by executioner caspases, granzyme B and several cysteine cathepsins in vitro. When apoptosis was induced by UV-irradiation and staurosporine in different epithelial cell lines, caspases were found to efficiently cleave MAGUKs in these cell models, as the cleavages could be prevented by a pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp(OMe)fluoromethylketone. Using a selective lysosomal disrupting agent -leucyl--leucine methyl ester, which induces apoptosis through the lysosomal pathway, it was further shown that MAGUKs are also cleaved by the cathepsins in HaCaT and CaCo-2 cells. Immunohistological data showed rapid loss of MAGUKs at the sites of cell–cell contacts, preceding actual cell detachment, suggesting that cleavage of MAGUKs is an important step in fast and efficient cell detachment.
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Affiliation(s)
- S Ivanova
- Department of Biochemistry and Molecular Biology, J Stefan Institute, Ljubljana, Slovenia
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10
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Zitranski N, Borth H, Ackermann F, Meyer D, Vieweg L, Breit A, Gudermann T, Boekhoff I. The "acrosomal synapse": Subcellular organization by lipid rafts and scaffolding proteins exhibits high similarities in neurons and mammalian spermatozoa. Commun Integr Biol 2010; 3:513-21. [PMID: 21331227 DOI: 10.4161/cib.3.6.13137] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 07/23/2010] [Accepted: 07/23/2010] [Indexed: 12/18/2022] Open
Abstract
Mammalian spermatozoa are highly polarized cells composed of two morphological and functional units, each optimized for a special task. Although the apparent division into head and tail may as such represent the anatomical basis to avoid random diffusion of their special sets of signaling proteins and lipids, recent findings demonstrate the presence of lipid raft-derived membrane platforms and specific scaffolding proteins, thus indicating that smaller sub-domains exist in the two functional units of male germ cells. The aim of this review is to summarize new insights into the principles of subcellular organization in mammalian spermatozoa. Special emphasis is placed on recent observations indicating that an "acrosomal synapse" is formed by lipid raft-derived membrane micro-environments and multidomain scaffolding proteins. Both mechanisms appear to be responsible for ensuring the attachment of the huge acrosomal vesicle to the overlaying plasma membrane, as well as for preventing an accidental spontaneous loss of the single acrosome.
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Affiliation(s)
- Nele Zitranski
- Walther-Straub-Institute of Pharmacology and Toxicology; Ludwig-Maximilians-University; Munich, Germany
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11
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Membrane estrogen receptors activate the metabotropic glutamate receptors mGluR5 and mGluR3 to bidirectionally regulate CREB phosphorylation in female rat striatal neurons. Neuroscience 2010; 170:1045-55. [PMID: 20709161 DOI: 10.1016/j.neuroscience.2010.08.012] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 07/13/2010] [Accepted: 08/09/2010] [Indexed: 01/16/2023]
Abstract
Along with its ability to directly regulate gene expression, estradiol influences cell signaling and brain functions via rapid, membrane-initiated events. In the female rat striatum, estradiol activates membrane-localized estrogen receptors to influence synaptic neurotransmission, calcium channel activity, and behaviors related to motor control. Yet, the mechanism by which estradiol acts to rapidly affect striatal physiology has remained elusive. Here we find that membrane estrogen receptors (ERs) couple to the metabotropic glutamate receptors mGluR5 and mGluR3, providing the framework to understand how membrane estrogen receptors affect striatal function. Using CREB phosphorylation as a downstream measure of ER/mGluR activation, membrane-localized estrogen receptor α (ERα) activates mGluR5 signaling to mediate mitogen-activated protein kinase (MAPK)-dependent CREB phosphorylation. Further, ERα and estrogen receptor β (ERβ) activate mGluR3 to attenuate L-type calcium channel-dependent CREB signaling. Interestingly, while this fundamental mechanism of ER/mGluR signaling was initially characterized in hippocampal neurons, estrogen receptors in striatal neurons are paired with a different set of mGluRs, resulting in the potential to functionally isolate membrane-initiated estrogen signaling across brain regions via use of specific mGluR modulators. These results provide both a mechanism for the rapid actions of estrogens within the female striatum, as well as demonstrate that estrogen receptors can interact with a more diverse set of surface membrane receptors than previously recognized.
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Momboisse F, Lonchamp E, Calco V, Ceridono M, Vitale N, Bader MF, Gasman S. betaPIX-activated Rac1 stimulates the activation of phospholipase D, which is associated with exocytosis in neuroendocrine cells. J Cell Sci 2009; 122:798-806. [PMID: 19261846 DOI: 10.1242/jcs.038109] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rho GTPases are crucial regulators of actin cytoskeletal rearrangements and play important roles in many cell functions linked to membrane trafficking processes. In neuroendocrine cells, we have previously demonstrated that RhoA and Cdc42 mediate part of the actin remodelling and vesicular trafficking events that are required for the release of hormones by exocytosis. Here, we investigate the functional importance of Rac1 for the exocytotic reaction and dissect the downstream and upstream molecular events that might integrate it to the exocytotic machinery. Using PC12 cells, we found that Rac1 is associated with the plasma membrane and is activated during exocytosis. Silencing of Rac1 by siRNA inhibits hormone release, prevents secretagogue (high K(+))-evoked phospholipase D1 (PLD1) activation and blocks the formation of phosphatidic acid at the plasma membrane. We identify betaPix as the guanine nucleotide-exchange factor integrating Rac1 activation to PLD1 and the exocytotic process. Finally, we show that the presence of the scaffolding protein Scrib at the plasma membrane is essential for betaPix/Rac1-mediated PLD1 activation and exocytosis. As PLD1 has recently emerged as a promoter of membrane fusion in various exocytotic events, our results define a novel molecular pathway linking a Rho GTPase, Rac1, to the final stages of Ca(2+)-regulated exocytosis in neuroendocrine cells.
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Affiliation(s)
- Fanny Momboisse
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Centre National de la Recherche Scientifique et Université de Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg, France
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13
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Shanmugam C, Katkoori VR, Jhala NC, Grizzle WE, Manne U. Immunohistochemical expression of rabphilin-3A-like (Noc2) in normal and tumor tissues of human endocrine pancreas. Biotech Histochem 2009; 84:39-45. [PMID: 19212825 DOI: 10.1080/10520290902738878] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Involvement of rabphilin-3A-like (RPH3AL), or Noc2, the potential effector of Ras-associated binding proteins Rab3A and Rab27A in the regulation of exocytotic processes in the endocrine pancreas has been demonstrated in experimental models. Noc2 expression together with other regulatory molecules of the exocytotic machinery in human tissues, however, has not been studied. We evaluated immunohistochemical expression of the key molecules of the exocytotic machinery, Noc2, Rab3A, Rab27A, and RIM2, together with the characteristic islet cell hormones, insulin and glucagon in normal and endocrine tumor tissues of human pancreas. Normal pancreatic islets were stained for all of these proteins and showed strong cytoplasmic localization. A similar pattern of strong cytoplasmic expression of these proteins was observed in the majority of endocrine tumors. By contrast, the exocrine portions of normal appearing pancreas completely lacked Rab27A staining and showed decreased expression of the proteins, Noc2, Rab3A, and RIM2. The staining pattern of Noc2 and Rab27A was similar to the staining pattern of glucagon-producing cells within the islets. The concomitant expression of Noc2 with these molecules suggests that Noc2 may serve as an effector for Rab3A and Rab27A and that it is involved in the regulation of exocytosis of the endocrine pancreas in humans.
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Affiliation(s)
- C Shanmugam
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294-7331, USA
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14
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Sun M, Liu L, Zeng X, Xu M, Liu L, Fang M, Xie W. Genetic interaction between Neurexin and CAKI/CMG is important for synaptic function in Drosophila neuromuscular junction. Neurosci Res 2009; 64:362-71. [PMID: 19379781 DOI: 10.1016/j.neures.2009.04.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 04/03/2009] [Accepted: 04/09/2009] [Indexed: 11/17/2022]
Abstract
Neurexins are neuron-specific cell surface molecules thought to localize to presynaptic membranes. Recent genetic studies using Drosophila melanogaster have implicated an essential role for a single Drosophila neurexin (dnrx) in the proper architecture, development and function of synapses in vivo. However, the precise mechanisms underlying these actions are not fully understood. To elucidate the molecular mechanism of Neurexin in vivo, we employed dnrx and caki mutant flies, combined with various methods, and analyzed the animals' locomotion, synaptic vesicle cycling and neurotransmission of neuromuscular junctions. We found that Dneurexin (DNRX) is important for locomotion through a genetic interaction with the scaffold protein, CAKI/CMG, the Drosophila homolog of vertebrate CASK. Similar to its mammalian counterparts, DNRX is essential for synaptic vesicle cycling, which plays critical roles in neurotransmission at neuromuscular junctions (NMJ). However, this interaction appears not to be required for the synaptic targeting of DNRX, but may instead be needed for proper synaptic function, possibly by regulating the synaptic vesicle cycling process.
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Affiliation(s)
- Mingkuan Sun
- Department of Genetics and Developmental Biology, Southeast University Medical School, The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, 87 Dingjiaqiao Road, Nanjing 210009, China
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15
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Refinement of the 12q14 microdeletion syndrome: primordial dwarfism and developmental delay with or without osteopoikilosis. Eur J Hum Genet 2009; 17:1141-7. [PMID: 19277063 DOI: 10.1038/ejhg.2009.27] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In their studies on the molecular basis of osteopoikilosis, Menten et al have identified three individuals with microdeletions on chromosome 12q14.4, which removed several genes including LEMD3, the osteopoikilosis gene. In addition to osteopoikilosis, affected individuals had growth retardation and developmental delay. We now report a smaller 12q14.4 microdeletion in a boy with severe pre and postnatal growth failure, and mild developmental delay; the patient was small at birth and presented with poor feeding and failure to thrive during the first 2 years of life, similar to the phenotype of primordial dwarfism or severe Silver-Russell syndrome (SRS). The 12q14 deletion did not include LEMD3, and no signs of osteopoikilosis were observed on skeletal radiographs. Among the deleted genes, HMGA2 is of particular interest in relationship to the aberrant somatic growth in our patient, as HMGA2 variants have been linked to stature variations in the general population and loss of function of Hmga2 in the mouse results in the pygmy phenotype that combines pre and postnatal growth failure, with resistance to the adipogenic effect of overfeeding. Sequencing of the remaining HMGA2 allele in our patient showed a normal sequence, suggesting that HMGA2 haploinsufficiency may be sufficient to produce the aberrant growth phenotype. We conclude that the 12q14.4 microdeletion syndrome can occur with or without deletion of LEMD3 gene; in LEMD3-intact cases, the phenotype includes primordial short stature and failure to thrive with moderate developmental delay, but osteopoikilosis is absent. Such cases will likely be diagnosed as Silver-Russell-like or as primordial dwarfism.
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16
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Luoma JI, Boulware MI, Mermelstein PG. Caveolin proteins and estrogen signaling in the brain. Mol Cell Endocrinol 2008; 290:8-13. [PMID: 18502030 PMCID: PMC2565274 DOI: 10.1016/j.mce.2008.04.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 04/05/2008] [Indexed: 01/08/2023]
Abstract
Best described outside the nervous system, caveolins are structural proteins that form caveolae, functional microdomains at the plasma membrane that cluster related signaling molecules. Caveolin-associated proteins include G protein-coupled receptors and G proteins, receptor tyrosine kinases, as well as protein kinases, ion channels and various other signaling enzymes. Not surprisingly, a wide array of biological disorders are thought to be rooted in caveolin dysfunction. In addition, caveolins traffic and cluster estrogen receptors to caveolae. Interactions between the estrogen receptors ERalpha and ERbeta with caveolins appear critical in many non-neuronal cell types, e.g., disruption of normal function may underlie many forms of breast cancer. Recent findings suggest caveolins may also play an essential role in membrane estrogen receptor function in the nervous system. Not only are they expressed in neurons and glia, but different caveolin isoforms also appear necessary to generate distinct functional signaling complexes. With membrane estrogen receptors responsible for the efficient activation of a multitude of intracellular signaling pathways, which in turn influence a wide variety of nervous system functions, caveolin proteins are poised to act as the central coordinators of these processes.
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Affiliation(s)
- Jessie I Luoma
- Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church Street S.E., Minneapolis, MN 55455, USA
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17
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Ikeda M, Inoue S, Muramatsu M, Minatogawa Y. Characterization and identification of a steroid receptor-binding protein, SRB-RGS. Biol Pharm Bull 2007; 30:1056-64. [PMID: 17541154 DOI: 10.1248/bpb.30.1056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We cloned the cDNA of a novel steroid receptor-binding protein, SRB-RGS, which suppressed the estrogen receptor (ER)alpha-mediated and other promoter-driven transcriptional activities. This study revealed the interaction between the full-length SRB-RGS and full-length ERalpha or ERbeta by a coimmunoprecipitation assay. The full-length SRB-RGS and full-length ERalpha interacted in COS-7 cell by a mammalian two-hybrid system. The interaction between intrinsic SRB-RGS and ERs in the nuclear ER extract from the rat uteri was observed by the gel-shift assay. These results strongly suggested that SRB-RGS interacts with ERs bound to DNA (estrogen response element) in the nuclei of the cells. SRB-RGS suppressed very efficiently the ERalpha-, ERbeta-, and ERalpha+ERbeta-mediated transcriptional activities. Green fluorescence of enhanced green fluorescence protein (EGFP)-tagged SRB-RGS was localized both in the nucleus and in the cytoplasm. Intrinsic SRB-RGS was immunostained in the nucleus and the cytoplasm of HeLa cells. The putative SRB-RGS deduced from cDNA sequence was identified by the immunostaining and Western blotting by using the anti-SRB-RGS antibody. Overexpression of SRB-RGS induced the cell death in the HeLa cells. The nucleotide sequence of SRB-RGS cDNA that we cloned previously is identical with that of the newly isolated RGS3 cDNA. SRB-RGS could interact with ERs bound DNA in the nuclei of the cells and suppressed the ERs-mediated transcriptional activities.
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MESH Headings
- Animals
- Base Sequence
- Blotting, Western
- COS Cells
- Cell Death
- Cell Nucleus/metabolism
- Chloramphenicol O-Acetyltransferase/analysis
- Chloramphenicol O-Acetyltransferase/metabolism
- Chlorocebus aethiops
- Cloning, Molecular
- Cytoplasm/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/metabolism
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Electrophoresis, Polyacrylamide Gel
- Estrogen Receptor alpha/genetics
- Estrogen Receptor alpha/metabolism
- Estrogen Receptor beta/genetics
- Estrogen Receptor beta/metabolism
- Female
- Fluorescent Antibody Technique, Direct
- Green Fluorescent Proteins/metabolism
- HeLa Cells
- Humans
- Immunohistochemistry
- Immunoprecipitation
- Microscopy, Confocal
- Protein Binding
- RGS Proteins
- Rats
- Rats, Sprague-Dawley
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Steroid/chemistry
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Repressor Proteins/chemistry
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic
- Two-Hybrid System Techniques
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Affiliation(s)
- Mitsunori Ikeda
- Department of Biochemistry, Kawasaki Medical School, Kurashiki, Okayama, Japan.
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18
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Menten B, Buysse K, Zahir F, Hellemans J, Hamilton SJ, Costa T, Fagerstrom C, Anadiotis G, Kingsbury D, McGillivray BC, Marra MA, Friedman JM, Speleman F, Mortier G. Osteopoikilosis, short stature and mental retardation as key features of a new microdeletion syndrome on 12q14. J Med Genet 2007; 44:264-8. [PMID: 17220210 PMCID: PMC2598049 DOI: 10.1136/jmg.2006.047860] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This report presents the detection of a heterozygous deletion at chromosome 12q14 in three unrelated patients with a similar phenotype consisting of mild mental retardation, failure to thrive in infancy, proportionate short stature and osteopoikilosis as the most characteristic features. In each case, this interstitial deletion was found using molecular karyotyping. The deletion occurred as a de novo event and varied between 3.44 and 6 megabases (Mb) in size with a 3.44 Mb common deleted region. The deleted interval was not flanked by low-copy repeats or segmental duplications. It contains 13 RefSeq genes, including LEMD3, which was previously shown to be the causal gene for osteopoikilosis. The observation of osteopoikilosis lesions should facilitate recognition of this new microdeletion syndrome among children with failure to thrive, short stature and learning disabilities.
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Affiliation(s)
- Björn Menten
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
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19
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Zordan MA, Massironi M, Ducato MG, Te Kronnie G, Costa R, Reggiani C, Chagneau C, Martin JR, Megighian A. Drosophila CAKI/CMG protein, a homolog of human CASK, is essential for regulation of neurotransmitter vesicle release. J Neurophysiol 2005; 94:1074-83. [PMID: 15872064 DOI: 10.1152/jn.00954.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vertebrate CASK is a member of the membrane-associated guanylate kinase (MAGUK) family of proteins. CASK is present in the nervous system where it binds to neurexin, a transmembrane protein localized in the presynaptic membrane. The Drosophila homologue of CASK is CAKI or CAMGUK. CAKI is expressed in the nervous system of larvae and adult flies. In adult flies, the expression of caki is particularly evident in the visual brain regions. To elucidate the functional role of CASK, we employed a caki null mutant in the model organism Drosophila melanogaster. By means of electrophysiological methods, we analyzed, in adult flies, the spontaneous and evoked neurotransmitter release at the neuromuscular junction (NMJ) as well as the functional status of the giant fiber pathway and of the visual system. We found that in caki mutants, when synaptic activity is modified, the spontaneous neurotransmitter release of the indirect flight muscle NMJ was increased, the response of the giant fiber pathway to continuous stimulation was impaired, and electroretinographic responses to single and continuous repetitive stimuli were altered and optomotor behavior was abnormal. These results support the involvement of CAKI in neurotransmitter release and nervous system function.
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Affiliation(s)
- Mauro A Zordan
- Department of Human Anatomy and Physiology, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8620, Université Paris Sud, Orsay, France
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20
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Yamada T, Ohoka Y, Kogo M, Inagaki S. Physical and functional interactions of the lysophosphatidic acid receptors with PDZ domain-containing Rho guanine nucleotide exchange factors (RhoGEFs). J Biol Chem 2005; 280:19358-63. [PMID: 15755723 DOI: 10.1074/jbc.m414561200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a serum-derived phospholipid that induces a variety of biological responses in various cells via heterotrimeric G protein-coupled receptors (GPCRs) including LPA1, LPA2, and LPA3. LPA-induced cytoskeletal changes are mediated by Rho family small GTPases, such as RhoA, Rac1, and Cdc42. One of these small GTPases, RhoA, may be activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors (RhoGEFs) under LPA stimulation although the detailed mechanisms are poorly understood. Here, we show that the C terminus of LPA1 and LPA2 but not LPA3 interact with the PDZ domains of PDZ domain-containing RhoGEFs, PDZ-RhoGEF, and LARG, which are comprised of PDZ, RGS, Dbl homology (DH), and pleckstrin homology (PH) domains. In LPA1- and LPA2-transfected HEK293 cells, LPA-induced RhoA activation was observed although the C terminus of LPA1 and LPA2 mutants, which failed to interact with the PDZ domains, did not cause LPA-induced RhoA activation. Furthermore, overexpression of the PDZ domains of PDZ domain-containing RhoGEFs served as dominant negative mutants for LPA-induced RhoA activation. Taken together, these results indicate that formation of the LPA receptor/PDZ domain-containing RhoGEF complex plays a pivotal role in LPA-induced RhoA activation.
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Affiliation(s)
- Takeshi Yamada
- School of Allied Health Sciences, Faculty of Medicine, Osaka University, Yamadaoka, Suita-shi, Osaka 565-0871, Japan
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21
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Kimura K, Kitano J, Nakajima Y, Nakanishi S. Hyperpolarization-activated, cyclic nucleotide-gated HCN2 cation channel forms a protein assembly with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction. Genes Cells 2005; 9:631-40. [PMID: 15265006 DOI: 10.1111/j.1356-9597.2004.00752.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperpolarization-activated cation currents, termed Ih, are non-uniformly distributed along dendritic arbors with current density increasing with increasing distance from the soma. The non-uniform distribution of Ih currents contributes to normalization of location-dependent variability in temporal integration of synaptic input, but the molecular basis for the graded HCN distribution remains to be investigated. The hyperpolarization-activated, cyclic nucleotide-gated cation channels (HCNs) underlie Ih currents and consist of four members (HCN1-HCN4) of the gene family in mammals. In this investigation, we report that HCN2 forms a protein assembly with tamalin, S-SCAM and Mint2 scaffold proteins, using several different approaches including immunoprecipitation of rat brain and heterologously expressing cell extracts and glutathione S-transferase pull-down assays. The PDZ domain of tamalin interacts with HCN2 at both the PDZ-binding motif and the internal carboxy-terminal tail of HCN2, whereas binding of the PDZ domain of S-SCAM occurs at the cyclic nucleotide-binding domain (CNBD) and the CNBD-downstream sequence of the carboxy-terminal tail of HCN2. A protein assembly between HCN2 and Mint2 is formed by the interaction of the munc18-interacting domain of Mint2 with the CNBD-downstream sequence of HCN2. The results demonstrate that HCN2 forms a protein complex with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction.
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Affiliation(s)
- Kouji Kimura
- Department of Biological Sciences, Faculty of Medicine, and Department of Molecular and System Biology, Graduate School of Biostudies, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
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22
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Bader MF, Doussau F, Chasserot-Golaz S, Vitale N, Gasman S. Coupling actin and membrane dynamics during calcium-regulated exocytosis: a role for Rho and ARF GTPases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1742:37-49. [PMID: 15590054 DOI: 10.1016/j.bbamcr.2004.09.028] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 09/22/2004] [Accepted: 09/24/2004] [Indexed: 10/26/2022]
Abstract
Release of neurotransmitters and hormones occurs by calcium-regulated exocytosis, a process that shares many similarities in neurons and neuroendocrine cells. Exocytosis is confined to specific regions in the plasma membrane, where actin remodelling, lipid modifications and protein-protein interactions take place to mediate vesicle/granule docking, priming and fusion. The spatial and temporal coordination of the various players to form a "fast and furious" machinery for secretion remain poorly understood. ARF and Rho GTPases play a central role in coupling actin dynamics to membrane trafficking events in eukaryotic cells. Here, we review the role of Rho and ARF GTPases in supplying actin and lipid structures required for synaptic vesicle and secretory granule exocytosis. Their possible functional interplay may provide the molecular cues for efficient and localized exocytotic fusion.
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Affiliation(s)
- Marie-France Bader
- CNRS UPR-2356 Neurotransmission and Sécrétion Neuroendocrine INSERM, 5 rue Blaise Pascal, 67084 Strasbourg, France.
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23
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Ehrengruber MU, Kato A, Inokuchi K, Hennou S. Homer/Vesl proteins and their roles in CNS neurons. Mol Neurobiol 2004; 29:213-27. [PMID: 15181235 DOI: 10.1385/mn:29:3:213] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Accepted: 10/23/2003] [Indexed: 01/10/2023]
Abstract
Since their initial discovery in 1997, Homer/Vesl proteins have become increasingly investigated as putative regulators of receptor and ion-channel function in the central nervous system. Within a relatively brief period, numerous research reports have described manifold effects of Homer proteins, including the modulation of the trafficking of type I metabotropic glutamate receptors (mGluRs), axonal pathfinding, mGluR coupling to calcium and potassium channels, agonist-independent mGluR activity, ryanodine receptor regulation, locomotor activity, and behavioral plasticity. This review summarizes our current knowledge on the induction, expression, and structure of the various forms of Homer proteins, as well as their roles in neuronal function. In addition, we provide an outlook on novel developments with regard to the involvement of Homer-1a in hippocampal synaptic function.
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Affiliation(s)
- Markus U Ehrengruber
- Kantonsschule Hohe Promenade, Promenadengasse 11, University of Zurich, Zurich, Switzerland.
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24
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McHugh EM, Zhu W, Milgram S, Mager S. The GABA transporter GAT1 and the MAGUK protein Pals1: interaction, uptake modulation, and coexpression in the brain. Mol Cell Neurosci 2004; 26:406-17. [PMID: 15234345 DOI: 10.1016/j.mcn.2004.03.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Revised: 02/04/2004] [Accepted: 03/16/2004] [Indexed: 12/30/2022] Open
Abstract
GABAergic signaling in the CNS is terminated in part through uptake of GABA by GABA transporters. We used the yeast two-hybrid system to identify proteins that associate with the carboxy-terminus of the neuronal GABA transporter GAT1. We found an interaction between GAT1 and the MAGUK protein Pals1. When coexpressed in COS-7 cells, Pals1 co-immunoprecipitates with GAT1. We demonstrate cellular coexpression of GAT1 and Pals1 in the mouse hippocampus and striatum. Functionally, coexpression of GAT1 and Pals1 in COS-7 cells increases [3H]-GABA uptake by GAT1. The mechanism underlying increased uptake is increased levels of GAT1 protein. We hypothesize that Pals1 contributes to the stability of the GAT1, thus promoting the expression level of the transporter protein. In the CNS, Pals1 may stabilize GAT1 at appropriate levels in specific GABAergic neurons.
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Affiliation(s)
- Ellen M McHugh
- Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC 27599, USA
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25
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Giffard RG, Lee YS, Ouyang YB, Murphy SL, Monyer H. Two variants of the rat brain sodium-driven chloride bicarbonate exchanger (NCBE): developmental expression and addition of a PDZ motif. Eur J Neurosci 2004; 18:2935-45. [PMID: 14656289 DOI: 10.1046/j.1460-9568.2003.03053.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Regulation of pH in the central nervous system is critical to normal brain function and response to pathophysiological conditions. Here we identify two novel variants of the sodium-driven chloride bicarbonate exchanger (NCBE) from brain. The developmental expression pattern seen by in situ hybridization for the 90-bp containing insert (insert A) reveals strong expression in spinal cord and brain beginning in embryonic development. High-level expression is seen in cerebellar Purkinje cells and principal cells in hippocampus. The variant missing a 39-bp insert at the 3' end (insert B) encodes a protein in which the deduced carboxyterminal three amino acids are replaced with a unique 21 amino acid stretch terminating in a PDZ motif. rb2NCBE, the PDZ motif-encoding variant, is more highly expressed in astrocytes than is rb1NCBE. Both variants are expressed at similar levels in neurons. Expression varies with age and cell type. The FLAG epitope was fused in-frame at the amino terminus and each variant was expressed using a retroviral vector to study subcellular localization. Both variants were associated with the plasma membrane, but rb2NCBE colocalized with actin filaments to a greater extent, suggesting the PDZ form may interact with the cytoskeleton, whereas rb1NCBE was more often seen in intracellular vesicles. The PDZ motif-containing variant was much more active in pH regulation, with the expected ionic dependence on Na+, HCO3- and Cl- when expressed in 3T3 cells. These results are a first step towards understanding the regulation of expression and activity of this transporter in the brain.
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Affiliation(s)
- Rona G Giffard
- Department of Anesthesia, S272, Stanford University, Stanford, CA 94305-5117, USA.
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26
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Sanford JL, Mays TA, Rafael-Fortney JA. CASK and Dlg form a PDZ protein complex at the mammalian neuromuscular junction. Muscle Nerve 2004; 30:164-71. [PMID: 15266631 DOI: 10.1002/mus.20073] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Membrane-associated guanylate kinases (MAGUKs) are modular adapter proteins that serve as scaffolding molecules and anchor channels and receptors via their PDZ (PSD-95, Dlg, Zo-1) domains. Calcium, calmodulin-associated serine/threonine kinase (CASK) is a MAGUK that is critical at synapses in the central nervous system and at cell-cell junctions because of its interactions with channels, receptors, and structural proteins. We show via confocal microscopy that CASK and another MAGUK, Discs Large (Dlg), are present at the mammalian neuromuscular junction in skeletal muscle. Immunoprecipitation data from mouse muscle show that CASK associates with Dlg, providing evidence of a MAGUK protein complex at this synapse. These data indicate that CASK and Dlg may act as a scaffold for organizing receptors and channels at the postsynaptic membrane of the neuromuscular junction.
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Affiliation(s)
- Jamie L Sanford
- Department of Molecular and Cellular Biochemistry, College of Medicine, Ohio State University, 410 Hamilton Hall, 1645 Neil Ave., Columbus, Ohio 43210, USA
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27
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Fang M, Tao YX, He F, Zhang M, Levine CF, Mao P, Tao F, Chou CL, Sadegh-Nasseri S, Johns RA. Synaptic PDZ domain-mediated protein interactions are disrupted by inhalational anesthetics. J Biol Chem 2003; 278:36669-75. [PMID: 12853458 DOI: 10.1074/jbc.m303520200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Anesthetics exert multiple effects on the central nervous system through altering synaptic transmission, but the mechanisms for this process are poorly understood. PDZ domain-mediated protein interactions play a central role in organizing signaling complexes around synaptic receptors for efficient signal transduction. We report here that clinically relevant concentrations of inhalational anesthetics dose-dependently and specifically inhibit the PDZ domain-mediated protein interaction between PSD-95 or PSD-93 and the N-methyl-d-aspartate receptor or neuronal nitric-oxide synthase. These inhibitory effects are immediate, potent, and reversible and occur at a hydrophobic peptide-binding groove on the surface of the second PDZ domain of PSD-95 in a manner relevant to anesthetic action. These findings reveal the PDZ domain as a new molecular target for inhalational anesthetics.
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Affiliation(s)
- Ming Fang
- Department of Anesthesiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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28
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Kitano J, Yamazaki Y, Kimura K, Masukado T, Nakajima Y, Nakanishi S. Tamalin is a scaffold protein that interacts with multiple neuronal proteins in distinct modes of protein-protein association. J Biol Chem 2003; 278:14762-8. [PMID: 12586822 DOI: 10.1074/jbc.m300184200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tamalin is a scaffold protein that comprises multiple protein-interacting domains, including a 95-kDa postsynaptic density protein (PSD-95)/discs-large/ZO-1 (PDZ) domain, a leucine-zipper region, and a carboxyl-terminal PDZ binding motif. Tamalin forms a complex with metabotropic glutamate receptors and guanine nucleotide exchange factor cytohesins and promotes intracellular trafficking and cell surface expression of group 1 metabotropic glutamate receptors. In the present study, using several different approaches we have shown that tamalin interacts with multiple neuronal proteins through its distinct protein-binding domains. The PDZ domain of tamalin binds to the PDZ binding motifs of SAP90/PSD-95-associated protein and tamalin itself, whereas the PDZ binding motif of tamalin is capable of interacting with the PDZ domain of S-SCAM. In addition, tamalin forms a complex with PSD-95 and Mint2/X11beta/X11L by mechanisms different from the PDZ-mediated interaction. Tamalin has the ability to assemble with these proteins in vivo; their protein complex with tamalin was verified by coimmunoprecipitation of rat brain lysates. Interestingly, the distinct protein-interacting domains of tamalin are evolutionarily conserved, and mRNA expression is developmentally up-regulated at the postnatal period. The results indicate that tamalin exists as a key element that forms a protein complex with multiple postsynaptic and protein-trafficking scaffold proteins.
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Affiliation(s)
- Jun Kitano
- Department of Biological Sciences, Faculty of Medicine, and the Department of Molecular and System Biology, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
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29
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Kajii Y, Muraoka S, Hiraoka S, Fujiyama K, Umino A, Nishikawa T. A developmentally regulated and psychostimulant-inducible novel rat gene mrt1 encoding PDZ-PX proteins isolated in the neocortex. Mol Psychiatry 2003; 8:434-44. [PMID: 12740601 DOI: 10.1038/sj.mp.4001258] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Single or repeated exposure to psychostimulants such as amphetamines and cocaine after postnatal week 3 leads to an enduring enhancement in the psychotomimetic responses elicited by a subsequent challenge of a stimulant in rodents. This behavioral sensitization phenomenon has been considered to be the neural consequences of stimulant-induced alterations in gene expression in the brain after a critical period of postnatal development. Using a differential cloning technique, RNA arbitrarily primed PCR, we have now identified from the rat neocortex a novel and developmentally regulated methamphetamine (MAP)-inducible gene mrt1 (MAP responsive transcript 1). mrt1 encodes two major types of PDZ- and PX-domains containing proteins of approximately 62 kDa in size with different carboxy termini, Mrt1a and Mrt1b. The mrt1 mRNAs for Mrt1a, mrt1a, and for Mrt1b, mrt1b, are predominantly expressed in various brain regions and the testes, respectively. Acute MAP injection upregulated mrt1b expression in the neocortex after postnatal week 3 in a D1 receptor antagonist-sensitive manner without affecting mrt1a expression. This upregulation was mimicked by another stimulant, cocaine, whereas pentobarbital and D1 antagonist failed to change the mrt1b transcript levels. Moreover, repeated daily treatment of MAP, but not MAP plus D1 antagonist, for 5 days caused an augmentation of the basal expression of mrt1b 2 and 3 weeks after the drug discontinuation. These late-developing, cocaine-crossreactive, D1 antagonist-sensitive and long-term regulations of mrt1b by MAP are similar to the pharmacological profiles of stimulant-induced behavioral sensitization, and therefore may be associated with the initiation and/or maintenance of the long-term neuronal adaptation.
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Affiliation(s)
- Y Kajii
- Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
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30
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Schuh K, Uldrijan S, Gambaryan S, Roethlein N, Neyses L. Interaction of the plasma membrane Ca2+ pump 4b/CI with the Ca2+/calmodulin-dependent membrane-associated kinase CASK. J Biol Chem 2003; 278:9778-83. [PMID: 12511555 DOI: 10.1074/jbc.m212507200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Spatial and temporal regulation of intracellular Ca(2+) is a key event in many signaling pathways. Plasma membrane Ca(2+)-ATPases (PMCAs) are major regulators of Ca(2+) homeostasis and bind to PDZ (PSD-95/Dlg/ZO-1) domains via their C termini. Various membrane-associated guanylate kinase family members have been identified as interaction partners of PMCAs. In particular, SAP90/PSD95, PSD93/chapsyn-110, SAP97, and SAP102 all bind to the C-terminal tails of PMCA "b" splice variants. Additionally, it has been demonstrated that PMCA4b interacts with neuronal nitric-oxide synthase and that isoform 2b interacts with Na(+)/H(+) exchanger regulatory factor 2, both via a PDZ domain. CASK (calcium/calmodulin-dependent serine protein kinase) contains a calmodulin-dependent protein kinase-like domain followed by PDZ, SH3, and guanylate kinase-like domains. In adult brain CASK is located at neuronal synapses and interacts with various proteins, e.g. neurexin and Veli/LIN-7. In kidney it is localized to renal epithelia. Surprisingly, interaction with the Tbr-1 transcription factor, nuclear transport, binding to DNA T-elements (in a complex with Tbr-1), and transcriptional competence has been shown. Here we show that the C terminus of PMCA4b binds to CASK and that both proteins co-precipitate from brain and kidney tissue lysates. Immunofluorescence staining revealed co-expression of PMCA, CASK, and calbindin-d-28K in distal tubuli of rat kidney sections. To test if physical interaction of both proteins results in functional consequences we constructed a T-element-dependent reporter vector and investigated luciferase activity in HEK293 lysates, previously co-transfected with PMCA4b expression and control vectors. Expression of wild-type PMCA resulted in an 80% decrease in T-element-dependent transcriptional activity, whereas co-expression of a point-mutated PMCA, with nearly eliminated Ca(2+) pumping activity, had only a small influence on regulation of transcriptional activity. These results provide evidence of a new direct Ca(2+)-dependent link from the plasma membrane to the nucleus.
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Affiliation(s)
- Kai Schuh
- Department of Medicine, University of Wuerzburg, D-97080 Wuerzburg, Germany
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Ohtakara K, Nishizawa M, Izawa I, Hata Y, Matsushima S, Taki W, Inada H, Takai Y, Inagaki M. Densin-180, a synaptic protein, links to PSD-95 through its direct interaction with MAGUIN-1. Genes Cells 2002; 7:1149-60. [PMID: 12390249 DOI: 10.1046/j.1365-2443.2002.00589.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Densin-180, a brain-specific protein highly concentrated at the postsynaptic density (PSD), belongs to the LAP [leucine-rich repeats and PSD-95/Dlg-A/ZO-1 (PDZ) domains] family of proteins, some of which play fundamental roles in the establishment of cell polarity. RESULTS To identify new Densin-180-interacting proteins, we screened a yeast two-hybrid library using the COOH-terminal fragment of Densin-180 containing the PDZ domain as bait, and we isolated MAGUIN-1 as a Densin-180-binding protein. MAGUIN-1, a mammalian homologue of Drosophila connector enhancer of KSR (CNK), is known to interact with PSD-95 and has a short isoform, MAGUIN-2. The Densin-180 PDZ domain bound to the COOH-terminal PDZ domain-binding motif of MAGUIN-1. Densin-180 co-immunoprecipitated with MAGUIN-1 as well as with PSD-95 from the rat brain. In dissociated hippocampal neurones Densin-180 co-localized with MAGUINs and PSD-95, mainly at neuritic spines. In transfected cells, Densin-180 formed a ternary complex with MAGUIN-1 and PSD-95, whereas no association was detected between Densin-180 and PSD-95 in the absence of MAGUIN-1. MAGUIN-1 formed a dimer or multimer via the COOH-terminal leucine-rich region which is present in MAGUIN-1 but not in -2. Among the PDZ domains of PSD-95, the first was sufficient for interaction with MAGUIN-1. CONCLUSION These results suggest that the potential to dimerize or multimerize allows MAGUIN-1 to bind simultaneously to both Densin-180 and PSD-95, leading to the ternary complex assembly of these proteins at the postsynaptic membrane.
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Affiliation(s)
- Kazuhiro Ohtakara
- Division of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya, Aichi 464-8681, Japan
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Paarmann I, Spangenberg O, Lavie A, Konrad M. Formation of complexes between Ca2+.calmodulin and the synapse-associated protein SAP97 requires the SH3 domain-guanylate kinase domain-connecting HOOK region. J Biol Chem 2002; 277:40832-8. [PMID: 12189141 DOI: 10.1074/jbc.m205618200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian synapse-associated protein SAP97, a structural and functional homolog of Drosophila Dlg, is a membrane-associated guanylate kinase (MAGUK) that is present at pre- and postsynaptic sites as well as in epithelial cell-cell contact sites. It is a multidomain scaffolding protein that shares with other members of the MAGUK protein family a characteristic modular organization composed of three sequential protein interaction motifs known as PDZ domains, followed by an Src homology 3 (SH3) domain, and an enzymatically inactive guanylate kinase (GK)-like domain. Specific binding partners are known for each domain, and different modes of intramolecular interactions have been proposed that particularly involve the SH3 and GK domains and the so-called HOOK region located between these two domains. We identified the HOOK region as a specific site for calmodulin binding and studied the dynamics of complex formation of recombinant calmodulin and SAP97 by surface plasmon resonance spectroscopy. Binding of various SAP97 deletion constructs to immobilized calmodulin was strictly calcium-dependent. From the rate constants of association and dissociation we determined an equilibrium dissociation constant K(d) of 122 nm for the association of calcium-saturated calmodulin and a SAP97 fragment, which encompassed the entire SH3-HOOK-GK module. Comparative structure-based sequence analysis of calmodulin binding regions from various target proteins predicts variable affinities for the interaction of calmodulin with members of the MAGUK protein family. Our findings suggest that calmodulin could regulate the intramolecular interaction between the SH3, HOOK, and GK domains of SAP97.
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Affiliation(s)
- Ingo Paarmann
- Department of Molecular Genetics, Max Planck Institute for Biophysical Chemistry, Göttingen D-37070, Germany
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Hirotani M, Ohoka Y, Yamamoto T, Nirasawa H, Furuyama T, Kogo M, Matsuya T, Inagaki S. Interaction of plexin-B1 with PDZ domain-containing Rho guanine nucleotide exchange factors. Biochem Biophys Res Commun 2002; 297:32-7. [PMID: 12220504 DOI: 10.1016/s0006-291x(02)02122-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Rho family GTPase has been implicated in plexin-B1, a receptor for Semaphorin 4D (Sema4D), mediating signal transduction. Rho may also play a function in this signaling pathway as well as Rac, but the mechanisms for Rho regulation are poorly understood. In this study, we have identified two kinds of PDZ domain-containing Rho-specific guanine nucleotide exchange factors (RhoGEFs) as proteins interacting with plexin-B1 cytoplasmic domain. These PDZ domain-containing RhoGEFs showed significant homology to human KIAA0380 (PDZ-RhoGEF) and LARG (KIAA0382), respectively. Both KIAA0380 and LARG could bind plexin-B1 and a deletion mutant analysis of plexin-B1, KIAA0380 and LARG revealed that KIAA0380 and LARG bound plexin-B1 cytoplasmic tail through their PDZ domains. The tissue distribution analysis indicated that plexin-B1 was co-localized with KIAA0380 and LARG in various tissues. Immunocytochemical analysis showed that LARG was recruited to plasma membrane by plexin-B1. These results suggest that PDZ domain-containing RhoGEFs play a role in Sema4D-plexin-B1 mediating signal transduction.
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Affiliation(s)
- Mutsumi Hirotani
- Group of Neurobiology, School of Allied Health Sciences, Osaka University Faculty of Medicine, Yamadaoka 1-7, Suita-shi, Osaka 565-0871, Japan
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El Far O, Betz H. G-protein-coupled receptors for neurotransmitter amino acids: C-terminal tails, crowded signalosomes. Biochem J 2002; 365:329-36. [PMID: 12006104 PMCID: PMC1222699 DOI: 10.1042/bj20020481] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2002] [Accepted: 05/08/2002] [Indexed: 11/17/2022]
Abstract
G-protein-coupled receptors (GPCRs) represent a superfamily of highly diverse integral membrane proteins that transduce external signals to different subcellular compartments, including nuclei, via trimeric G-proteins. By differential activation of diffusible G(alpha) and membrane-bound G(beta)gamma subunits, GPCRs might act on both cytoplasmic/intracellular and plasma-membrane-bound effector systems. The coupling efficiency and the plasma membrane localization of GPCRs are regulated by a variety of interacting proteins. In this review, we discuss recently disclosed protein interactions found with the cytoplasmic C-terminal tail regions of two types of presynaptic neurotransmitter receptors, the group III metabotropic glutamate receptors and the gamma-aminobutyric acid type-B receptors (GABA(B)Rs). Calmodulin binding to mGluR7 and other group III mGluRs may provide a Ca(2+)-dependent switch for unidirectional (G(alpha)) versus bidirectional (G(alpha) and G(beta)gamma) signalling to downstream effector proteins. In addition, clustering of mGluR7 by PICK1 (protein interacting with C-kinase 1), a polyspecific PDZ (PSD-95/Dlg1/ZO-1) domain containing synaptic organizer protein, sheds light on how higher-order receptor complexes with regulatory enzymes (or 'signalosomes') could be formed. The interaction of GABA(B)Rs with the adaptor protein 14-3-3 and the transcription factor ATF4 (activating transcription factor 4) suggests novel regulatory pathways for G-protein signalling, cytoskeletal reorganization and nuclear gene expression: processes that may all contribute to synaptic plasticity.
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Affiliation(s)
- Oussama El Far
- Max-Planck Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt/Main, Germany
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Kimple ME, Siderovski DP, Sondek J. Functional relevance of the disulfide-linked complex of the N-terminal PDZ domain of InaD with NorpA. EMBO J 2001; 20:4414-22. [PMID: 11500369 PMCID: PMC125561 DOI: 10.1093/emboj/20.16.4414] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2001] [Revised: 06/25/2001] [Accepted: 06/25/2001] [Indexed: 11/13/2022] Open
Abstract
In Drosophila, phototransduction is mediated by G(q)-activation of phospholipase C and is a well studied model system for understanding the kinetics of signal initiation, propagation and termination controlled by G proteins. The proper intracellular targeting and spatial arrangement of most proteins involved in fly phototransduction require the multi-domain scaffolding protein InaD, composed almost entirely of five PDZ domains, which independently bind various proteins including NorpA, the relevant phospho lipase C-beta isozyme. We have determined the crystal structure of the N-terminal PDZ domain of InaD bound to a peptide corresponding to the C-terminus of NorpA to 1.8 A resolution. The structure highlights an intermolecular disulfide bond necessary for high affinity interaction as determined by both in vitro and in vivo studies. Since other proteins also possess similar, cysteine-containing consensus sequences for binding PDZ domains, this disulfide-mediated 'dock-and-lock' interaction of PDZ domains with their ligands may be a relatively ubiquitous mode of coordinating signaling pathways.
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Affiliation(s)
- Michelle E. Kimple
- Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, Department of Pharmacology, Lineberger Comprehensive Cancer Center and Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA Corresponding author e-mail:
| | - David P. Siderovski
- Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, Department of Pharmacology, Lineberger Comprehensive Cancer Center and Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA Corresponding author e-mail:
| | - John Sondek
- Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, Department of Pharmacology, Lineberger Comprehensive Cancer Center and Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA Corresponding author e-mail:
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Yang HY, Wilkening S, Iadarola MJ. Spinal cord genes enriched in rat dorsal horn and induced by noxious stimulation identified by subtraction cloning and differential hybridization. Neuroscience 2001; 103:493-502. [PMID: 11246163 DOI: 10.1016/s0306-4522(00)00573-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Persistent nociceptive input increases neuronal excitability and induces a program of gene expression in the dorsal spinal cord. The alteration in gene expression commences with phosphorylation and induction of immediate early genes and proceeds to target genes. Only a few target genes have been identified as yet. The present report uses a polymerase chain reaction-based subtraction cloning procedure to obtain an "anatomically focused" complementary DNA library enriched in transcripts related to sensory spinal cord (rat dorsal horn minus ventral horn). A subset of clones from this library (n=158) was screened to verify dorsal horn enrichment and to identify those regulated by carrageenan-induced peripheral inflammation. Molecular classes which displayed enriched expression included a proto-oncogene not previously associated with sensory processes, two regulators of the Rho/Rac pathway which controls cell shape, and three genes involved in cytoskeletal regulation and scaffolding. Additional transcripts coded for proteins involved in intercellular communication or intracellular function. Within the set of 158 transcripts, one known and two unknown genes were induced by persistent noxious input. The known gene codes for the secreted cysteine proteinase inhibitor, cystatin C, suggesting that modulation of extracellular proteolytic activity occurs. Since it is secreted, cystatin C may also provide a cerebrospinal fluid bio-marker for persistent pain states. Using a combined anatomical and functional approach, we have extended the molecular repertoire of genes expressed and induced in second-order neurons or supporting glial cells in several new directions, with particular emphasis on regulation of cell morphology and plasma membrane dynamics. Some of these proteins reveal new pathways for information signaling in the sensory half of the spinal cord and require further research to understand their role in the adult spinal cord. The induced genes may provide new molecular targets for therapeutic development and provide new probes for investigating the dynamic state of cellular activity that occurs during persistent pain states.
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Affiliation(s)
- H Y Yang
- Neuronal Gene Expression Unit, Pain and Neurosensory Mechanisms Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Building 49, 49 Convent Drive, MSC 4410, Bethesda, MD 20892-4410, USA.
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Yamada K, Fukaya M, Shimizu H, Sakimura K, Watanabe M. NMDA receptor subunits GluRepsilon1, GluRepsilon3 and GluRzeta1 are enriched at the mossy fibre-granule cell synapse in the adult mouse cerebellum. Eur J Neurosci 2001; 13:2025-36. [PMID: 11422443 DOI: 10.1046/j.0953-816x.2001.01580.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cerebellar N-methyl-D-aspartate (NMDA) receptors are concentrated in the granular layer and are involved in motor coordination and the induction of long-term potentiation at mossy fibre-granule cell synapses. In the present study, we used immunohistochemistry to examine the distribution of NMDA receptor subunits in the adult mouse cerebellum. We found that appropriate pepsin pretreatment of sections greatly enhanced the sensitivity and specificity of immunohistochemical detection. As a result, intense immunolabelling for GluRepsilon1 (NR2A), GluRepsilon3 (NR2C), and GluRzeta1 (NR1) all appeared in synaptic glomeruli of the granular layer. Double immunofluorescence showed that these subunits were colocalized in individual synaptic glomeruli. Within the glomerulus, NMDA receptor subunits were located between centrally-located huge mossy fibre terminals and peripherally-located tiny Golgi axon terminals. By immunoelectron microscopy, all three subunits were detected at the postsynaptic junction in granule cell dendrites, forming synapses with mossy fibre terminals. Consistent with the known functional localization, GluRepsilon1, GluRepsilon3, and GluRzeta1 are, thus, anatomically concentrated at the mossy fibre-granule cell synapse. By contrast, immunohistochemical signals were very low in Purkinje cell somata and dendrites in the molecular layer. The lack of GluRzeta1 immunolabelling in Purkinje cells was unexpected because the cells express GluRzeta1 mRNA at high levels and high levels of GluRzeta1 protein in the molecular layer were revealed by immunoblot. As Purkinje cells are exceptionally lacking GluRepsilon expression, the discrepant result may provide in vivo evidence suggesting the importance of accompanying GluRepsilon subunits in synaptic localization of GluRzeta1.
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Affiliation(s)
- K Yamada
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
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38
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Abstract
The recent success of large-scale industrialized genomic sequencing opens new doors in studies of biological systems. In the current post-genomic era we must ask how to translate this DNA sequence information into an understanding of living cells, tissues and organisms. One of the major goals is to characterize protein function, biochemical pathways and networks. Achieving this aim is greatly advanced by application of new proteomic tools combined with database mining. Neuroscience in particular is poised to benefit from these approaches in light of its high complexity and cross-talk between different neurotransmitter receptors within the same synapse or across the synaptic cleft. Little is known about the global in vivo protein interactions within synapses, and the knowledge of all proteins present in such structures will help in determining sub-complexes and the modular arrangement of proteins within them. This article reviews the impact of and outlines the application of proteomic analysis in the field of neuroscience, illustrating this with the example of NMDA receptor complexes.
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Affiliation(s)
- H Husi
- Dept of Neuroscience, University of Edinburgh, 1 George Square, Edinburgh, UK, EH9 9JZ
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Abstract
Tight junctions are one mode of cell-cell adhesion in epithelial and endothelial cellular sheets. They act as a primary barrier to the diffusion of solutes through the intercellular space, create a boundary between the apical and the basolateral plasma membrane domains, and recruit various cytoskeletal as well as signalling molecules at their cytoplasmic surface. New insights into the molecular architecture of tight junctions allow us to now discuss the structure and functions of this unique cell-cell adhesion apparatus in molecular terms.
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Affiliation(s)
- S Tsukita
- Department of Cell Biology, Kyoto University Faculty of Medicine, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
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40
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Ohoka Y, Hirotani M, Sugimoto H, Fujioka S, Furuyama T, Inagaki S. Semaphorin 4C, a transmembrane semaphorin, [corrected] associates with a neurite-outgrowth-related protein, SFAP75. Biochem Biophys Res Commun 2001; 280:237-43. [PMID: 11162505 DOI: 10.1006/bbrc.2000.4080] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Semaphorin 4C (S4C, previously called M-SemaF) was recently identified as a brain rich transmembrane member of semaphorin family of the vertebrate. In the cytoplasmic domain of S4C there is a proline-rich region suggesting that the cytoplasmic domain may play an important role in Sema4C function. In this study, we have identified the cytoplasmic domain (cd) of M-SemaF(S4C)-associating protein with a Mr of 75 kDa, named SFAP75, from mouse brain. SFAP75 turned out to be the same as the recently reported neurite-outgrowth-related protein named Norbin. Deletion mutants analyses of S4C and SFAP75 revealed that the membrane-proximal region of S4Ccd binds to the intermediate region of SFAP75. Western blot and immunohistochemical analyses with anti-Sema4C and anti-SFAP75 antibodies indicated that S4C and SFAP75 were specially enriched in the brain with a similar distribution pattern to each other. These results suggest that S4C interacts with SFAP75 and plays a role in neural function in brain.
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Affiliation(s)
- Y Ohoka
- Group of Neurobiology, School of Allied Health Sciences, Osaka University Faculty of Medicine, Yamadaoka 1-7, Suita-shi, Osaka, 565-0871, Japan.
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Abstract
Small GTP-binding proteins (G proteins) exist in eukaryotes from yeast to human and constitute a superfamily consisting of more than 100 members. This superfamily is structurally classified into at least five families: the Ras, Rho, Rab, Sar1/Arf, and Ran families. They regulate a wide variety of cell functions as biological timers (biotimers) that initiate and terminate specific cell functions and determine the periods of time for the continuation of the specific cell functions. They furthermore play key roles in not only temporal but also spatial determination of specific cell functions. The Ras family regulates gene expression, the Rho family regulates cytoskeletal reorganization and gene expression, the Rab and Sar1/Arf families regulate vesicle trafficking, and the Ran family regulates nucleocytoplasmic transport and microtubule organization. Many upstream regulators and downstream effectors of small G proteins have been isolated, and their modes of activation and action have gradually been elucidated. Cascades and cross-talks of small G proteins have also been clarified. In this review, functions of small G proteins and their modes of activation and action are described.
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Affiliation(s)
- Y Takai
- Department of Molecular Biology, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita, Japan.
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Mino A, Ohtsuka T, Inoue E, Takai Y. Membrane-associated guanylate kinase with inverted orientation (MAGI)-1/brain angiogenesis inhibitor 1-associated protein (BAP1) as a scaffolding molecule for Rap small G protein GDP/GTP exchange protein at tight junctions. Genes Cells 2000; 5:1009-16. [PMID: 11168587 DOI: 10.1046/j.1365-2443.2000.00385.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Membrane-associated guanylate kinase (MAGUK) with inverted orientation (MAGI)-1/brain angiogenesis inhibitor 1-associated protein (BAP1), is a member of the MAGUK family that has multiple PDZ domains and interacts with many transmembrane proteins, including receptors and channels, through these domains. MAGI-1/BAP1 is ubiquitously expressed and localized at tight junctions in epithelial cells. It is an isoform of the neurone-specific synaptic scaffolding molecule (S-SCAM), which is known to interact with NMDA receptors and neuroligins. We have recently found that S-SCAM also interacts with a signalling molecule, a GDP/GTP exchange protein (GEP) that is specific for Rap1 small G protein, Rap GEP, which has also recently been referred to as RA-GEF/PDZ-GEFI/CNras-GEF. In this study, we have examined whether MAGI-1/BAP1 also interacts with and serves as a scaffolding molecule for Rap GEP at tight junctions in epithelial cells. RESULTS MAGI-1/BAP1 similarly interacted with Rap GEP in cell-free and intact cell systems. A Northern blot analysis revealed that Rap GEP was expressed in most tissues examined. However, neither postsynaptic density (PSD)-95/synapse-associated protein (SAP) 90 (another member of the MAGUK family) nor SAP97/human discs-large tumour suppressor gene product (another ubiquitously expressed MAGUK localizing to adherens junctions in epithelial cells and the isoform of PSD-95/SAP90) interacted with Rap GEP. CONCLUSION These results indicate that MAGI-1/BAP1 serves as a scaffolding molecule for Rap GEP at tight junctions in epithelial cells.
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Affiliation(s)
- A Mino
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita 565-0871, Japan
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Wu H, Reissner C, Kuhlendahl S, Coblentz B, Reuver S, Kindler S, Gundelfinger ED, Garner CC. Intramolecular interactions regulate SAP97 binding to GKAP. EMBO J 2000; 19:5740-51. [PMID: 11060025 PMCID: PMC305801 DOI: 10.1093/emboj/19.21.5740] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Membrane-associated guanylate kinase homologs (MAGUKs) are multidomain proteins found to be central organizers of cellular junctions. In this study, we examined the molecular mechanisms that regulate the interaction of the MAGUK SAP97 with its GUK domain binding partner GKAP (GUK-associated protein). The GKAP-GUK interaction is regulated by a series of intramolecular interactions. Specifically, the association of the Src homology 3 (SH3) domain and sequences situated between the SH3 and GUK domains with the GUK domain was found to interfere with GKAP binding. In contrast, N-terminal sequences that precede the first PDZ domain in SAP97, facilitated GKAP binding via its association with the SH3 domain. Utilizing crystal structure data available for PDZ, SH3 and GUK domains, molecular models of SAP97 were generated. These models revealed that SAP97 can exist in a compact U-shaped conformation in which the N-terminal domain folds back and interacts with the SH3 and GUK domains. These models support the biochemical data and provide new insights into how intramolecular interactions may regulate the association of SAP97 with its binding partners.
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Affiliation(s)
- H Wu
- University of Alabama at Birmingham, Department of Neurobiology, 1719 Sixth Avenue South CIRC 589, Birmingham, AL 35294-0021, USA
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Deguchi M, Iizuka T, Hata Y, Nishimura W, Hirao K, Yao I, Kawabe H, Takai Y. PAPIN. A novel multiple PSD-95/Dlg-A/ZO-1 protein interacting with neural plakophilin-related armadillo repeat protein/delta-catenin and p0071. J Biol Chem 2000; 275:29875-80. [PMID: 10896674 DOI: 10.1074/jbc.m005384200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A neural plakophilin-related armadillo repeat protein (NPRAP)/delta-catenin interacts with one of Alzheimer disease-related gene products, presenilin 1. We have previously reported the interaction of NPRAP/delta-catenin with synaptic scaffolding molecule, which is involved in the assembly of synaptic components. NPRAP/delta-catenin also interacts with E-cadherin and beta-catenin and is implicated in the organization of cell-cell junctions. p0071, a ubiquitous isoform of NPRAP/delta-catenin, is localized at desmosomes in HeLa and A431 cells and at adherens junctions in Madin-Darby bovine kidney cells. We have identified here a novel protein interacting with NPRAP/delta-catenin and p0071 and named this protein plakophilin-related armadillo repeat protein-interacting PSD-95/Dlg-A/ZO-1 (PDZ) protein (PAPIN). PAPIN has six PDZ domains and binds to NPRAP/delta-catenin and p0071 via the second PDZ domain. PAPIN and p0071 are ubiquitously expressed in various tissues and are localized at cell-cell junctions in normal rat kidney cells and bronchial epithelial cells. PAPIN may be a scaffolding protein connecting components of epithelial junctions with p0071.
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Affiliation(s)
- M Deguchi
- Takai Biotimer Project, Exploratory Research for Advanced Technology, Japan Science and Technology Corporation, c/o JCR Pharmaceuticals Co. Ltd., Kobe 651-2241, Japan
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Ort T, Maksimova E, Dirkx R, Kachinsky AM, Berghs S, Froehner SC, Solimena M. The receptor tyrosine phosphatase-like protein ICA512 binds the PDZ domains of beta2-syntrophin and nNOS in pancreatic beta-cells. Eur J Cell Biol 2000; 79:621-30. [PMID: 11043403 DOI: 10.1078/0171-9335-00095] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Islet cell autoantigen (ICA) 512 of type I diabetes is a receptor tyrosine phosphatase-like protein associated with the secretory granules of neurons and endocrine cells including insulin-secreting beta-cells of the pancreas. Here we show that in a yeast two-hybrid assay its cytoplasmic domain binds beta2-syntrophin, a modular adapter which in muscle cells interacts with members of the dystrophin family including utrophin, as well as the signaling molecule neuronal nitric oxide synthase (nNOS). The cDNA isolated by two-hybrid screening corresponded to a novel beta2-syntrophin isoform with a predicted molecular mass of 28 kDa. This isoform included the PDZ domain, but not the C-terminal region, which in full-length beta2-syntrophin is responsible for binding dystrophin-related proteins. In vitro binding of the beta2-syntrophin PDZ domain to ICA512 required both ICA512's C-terminal region and an internal polypeptide preceding its tyrosine phosphatase-like domain. Immunomicroscopy and co-immunoprecipitations from insulinoma INS-1 cells confirmed the occurrence of ICA512-beta2-syntrophin complexes in vivo. ICA512 also interacted in vitro with the PDZ domain of nNOS and ICA512-nNOS complexes were co-immunoprecipitated from INS-1 cells. Finally, we show that INS-1 cells, like muscle cells, contain beta2-syntrophin-utrophin oligomers. Thus, we propose that ICA512, through beta2-syntrophin and nNOS, links secretory granules with the actin cytoskeleton and signaling pathways involving nitric oxide.
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Affiliation(s)
- T Ort
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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46
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Linares JL, Wendling C, Tomasetto C, Rio MC. C2PA, a new protein expressed during mouse spermatogenesis. FEBS Lett 2000; 480:249-54. [PMID: 11034339 DOI: 10.1016/s0014-5793(00)01942-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
C2PA is a novel protein that contains a C2 membrane binding domain, a PDZ protein/protein interaction domain, and an ATP/GTP binding domain. C2PA is expressed during embryogenesis from 8.5 days post-coitum (dpc) until birth. After birth, C2PA expression is mainly observed in the post-natal and adult testis. During spermatogenesis, C2PA transcripts are specifically observed in the spermatocytes, whereas spermatogonia and spermatids are negative. Taken together, these results suggest that C2PA might be involved in cell signaling pathways occurring during spermatogenesis.
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Affiliation(s)
- J L Linares
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM U184/ULP BP 163, Illkirch, CU de Strasbourg, France
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47
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Abstract
Synaptic junctions are highly specialized structures designed to promote the rapid and efficient transmission of signals from the presynaptic terminal to the postsynaptic membrane within the central nervous system. Proteins containing PDZ domains play a fundamental organizational role at both the pre- and postsynaptic plasma membranes. This review focuses on recent advances in our understanding of the mechanisms underlying the assembly of synapses in the central nervous system.
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Affiliation(s)
- C C Garner
- Dept of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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48
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Iezzi M, Regazzi R, Wollheim CB. The Rab3-interacting molecule RIM is expressed in pancreatic beta-cells and is implicated in insulin exocytosis. FEBS Lett 2000; 474:66-70. [PMID: 10828453 DOI: 10.1016/s0014-5793(00)01572-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The putative Rab3 effector RIM (Rab3-interacting molecule) was detected by Northern blotting, RT-PCR and Western blotting in native pancreatic beta-cells as well as in the derived cell lines INS-1E and HIT-T15. RIM was localized on the plasma membrane of INS-1E cells and beta-cells. An involvement of RIM in insulin exocytosis was indicated by transfection experiments of INS-1E cells with the Rab3 binding domain of RIM. This domain enhanced glucose-stimulated secretion in intact cells and Ca(2+)-stimulated exocytosis in permeabilized cells. Co-expression of Rab3A reversed the effect of RIM on exocytosis. These results suggest an implication of RIM in the control of insulin secretion.
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Affiliation(s)
- M Iezzi
- Division de Biochimie Clinique, Centre Médical Universitaire, Departement de Médecine Interne, Université de Genevé, Switzerland
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49
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Dobrosotskaya IY, James GL. MAGI-1 interacts with beta-catenin and is associated with cell-cell adhesion structures. Biochem Biophys Res Commun 2000; 270:903-9. [PMID: 10772923 DOI: 10.1006/bbrc.2000.2471] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The family of membrane-associated guanylate kinases (MAGUK) comprises peripheral membrane proteins involved in the formation of specialized cell-cell junctions. MAGUK proteins possess a conserved domain composition, containing PDZ, guanylate kinase, and SH3 or WW domains. MAGI-1 is a recently identified member of the MAGUK protein family. Three splice variantsof MAGI-1 have been characterized to date, including MAGI-1a, -1b, and -1c. MAGI-1b is predominantly associated with the crude membrane fraction. Here we show that the fifth PDZ domain of MAGI-1b is essential for membrane localization. We have also identified beta-catenin as a potential ligand for this PDZ domain. MAGI-1b forms complexes with beta-catenin and E-cadherin during the formation of cell-cell junctions in MDCK cells. In agreement with this observation, a significant portion of a GFP fusion of MAGI-1b localizes to the basolateral membrane of polarized MDCK cells.
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Affiliation(s)
- I Y Dobrosotskaya
- Graduate Program in Cell Regulation, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75235, USA.
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50
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Abstract
alpha-Amino-3-hydroxy-5-methylisoxazolepropionate (AMPA) receptors mediate most fast excitatory synaptic transmission in the mammalian CNS. They play a central role in synapse stabilisation and plasticity and their prolonged activation is potently neurotoxic. Developmental and activity-dependent changes in the functional synaptic expression of these receptors are subject to tight cellular regulation. The molecular and cellular mechanisms which control the postsynaptic insertion and arrangement of individual AMPA receptor variants are therefore the subject of intense investigation and in the last two years there has been significant progress towards elucidating some of the processes involved. Much of the new information has come from the application of the yeast two-hybrid assay, which has led to the discovery of a hitherto unexpected complexity of proteins which selectively interact with individual AMPA receptor subunits. These proteins have been implicated in the regulation of AMPA receptor post-translational modification, targeting and trafficking, surface expression and anchoring. The aim of this article is to present an overview of the major interacting proteins described so far and to place these in the context of how they may participate in the well ordered series of events controlling the cell biology of AMPA receptors.
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Affiliation(s)
- S P Braithwaite
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Science, University of Bristol, University Walk, Bristol, UK
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