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Cooper JN, Mittal J, Sangadi A, Klassen DL, King AM, Zalta M, Mittal R, Eshraghi AA. Landscape of NRXN1 Gene Variants in Phenotypic Manifestations of Autism Spectrum Disorder: A Systematic Review. J Clin Med 2024; 13:2067. [PMID: 38610832 PMCID: PMC11012327 DOI: 10.3390/jcm13072067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/21/2024] [Accepted: 03/29/2024] [Indexed: 04/14/2024] Open
Abstract
Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by social communication challenges and repetitive behaviors. Recent research has increasingly focused on the genetic underpinnings of ASD, with the Neurexin 1 (NRXN1) gene emerging as a key player. This comprehensive systematic review elucidates the contribution of NRXN1 gene variants in the pathophysiology of ASD. Methods: The protocol for this systematic review was designed a priori and was registered in the PROSPERO database (CRD42023450418). A risk of bias analysis was conducted using the Joanna Briggs Institute (JBI) critical appraisal tool. We examined various studies that link NRXN1 gene disruptions with ASD, discussing both the genotypic variability and the resulting phenotypic expressions. Results: Within this review, there was marked heterogeneity observed in ASD genotypic and phenotypic manifestations among individuals with NRXN1 mutations. The presence of NRXN1 mutations in this population emphasizes the gene's role in synaptic function and neural connectivity. Conclusion: This review not only highlights the role of NRXN1 in the pathophysiology of ASD but also highlights the need for further research to unravel the complex genetic underpinnings of the disorder. A better knowledge about the multifaceted role of NRXN1 in ASD can provide crucial insights into the neurobiological foundations of autism and pave the way for novel therapeutic strategies.
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Affiliation(s)
- Jaimee N. Cooper
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
- School of Medicine, New York Medical College, Valhalla, NY 10595, USA
| | - Jeenu Mittal
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
| | - Akhila Sangadi
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
| | - Delany L. Klassen
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
| | - Ava M. King
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
| | - Max Zalta
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
| | - Rahul Mittal
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
| | - Adrien A. Eshraghi
- Department of Otolaryngology, Hearing Research and Communication Disorders Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (J.N.C.); (J.M.); (A.S.); (D.L.K.); (A.M.K.); (M.Z.); (R.M.)
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146, USA
- Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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Noborn F, Sterky FH. Role of neurexin heparan sulfate in the molecular assembly of synapses - expanding the neurexin code? FEBS J 2023; 290:252-265. [PMID: 34699130 DOI: 10.1111/febs.16251] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 09/21/2021] [Accepted: 10/25/2021] [Indexed: 02/05/2023]
Abstract
Synapses are the minimal information processing units of the brain and come in many flavors across distinct circuits. The shape and properties of a synapse depend on its molecular organisation, which is thought to largely depend on interactions between cell adhesion molecules across the synaptic cleft. An established example is that of presynaptic neurexins and their interactions with structurally diverse postsynaptic ligands: the diversity of neurexin isoforms that arise from alternative promoters and alternative splicing specify synaptic properties by dictating ligand preference. The recent finding that a majority of neurexin isoforms exist as proteoglycans with a single heparan sulfate (HS) polysaccharide adds to this complexity. Sequence motifs within the HS polysaccharide may differ between neuronal cell types to contribute specificity to its interactions, thereby expanding the coding capacity of neurexin diversity. However, an expanding number of HS-binding proteins have been found capable to recruit neurexins via the HS chain, challenging the concept of a code provided by neurexin splice isoforms. Here we discuss the possible roles of the neurexin HS in light of what is known from other HS-protein interactions, and propose a model for how the neurexin HS polysaccharide may contribute to synaptic assembly. We also discuss how the neurexin HS may be regulated by co-secreted carbonic anhydrase-related and FAM19A proteins, and highlight some key issues that should be resolved to advance the field.
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Affiliation(s)
- Fredrik Noborn
- Department of Laboratory Medicine, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Fredrik H Sterky
- Department of Laboratory Medicine, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.,Department of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden.,Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden
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Computational Saturation Mutagenesis to Investigate the Effects of Neurexin-1 Mutations on AlphaFold Structure. Genes (Basel) 2022; 13:genes13050789. [PMID: 35627176 PMCID: PMC9141173 DOI: 10.3390/genes13050789] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/20/2022] [Accepted: 04/23/2022] [Indexed: 02/05/2023] Open
Abstract
Neurexin-1 (NRXN1) is a membrane protein essential in synapse formation and cell signaling as a cell-adhesion molecule and cell-surface receptor. NRXN1 and its binding partner neuroligin have been associated with deficits in cognition. Recent genetics research has linked NRXN1 missense mutations to increased risk for brain disorders, including schizophrenia (SCZ) and autism spectrum disorder (ASD). Investigation of the structure-function relationship in NRXN1 has proven difficult due to a lack of the experimental full-length membrane protein structure. AlphaFold, a deep learning-based predictor, succeeds in high-quality protein structure prediction and offers a solution for membrane protein model construction. In the study, we applied a computational saturation mutagenesis method to analyze the systemic effects of missense mutations on protein functions in a human NRXN1 structure predicted from AlphaFold and an experimental Bos taurus structure. The folding energy changes were calculated to estimate the effects of the 29,540 mutations of AlphaFold model on protein stability. The comparative study on the experimental and computationally predicted structures shows that these energy changes are highly correlated, demonstrating the reliability of the AlphaFold structure for the downstream bioinformatics analysis. The energy calculation revealed that some target mutations associated with SCZ and ASD could make the protein unstable. The study can provide helpful information for characterizing the disease-causing mutations and elucidating the molecular mechanisms by which the variations cause SCZ and ASD. This methodology could provide the bioinformatics protocol to investigate the effects of target mutations on multiple AlphaFold structures.
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Abstract
The function of neuronal circuits relies on the properties of individual neuronal cells and their synapses. We propose that a substantial degree of synapse formation and function is instructed by molecular codes resulting from transcriptional programmes. Recent studies on the Neurexin protein family and its ligands provide fundamental insight into how synapses are assembled and remodelled, how synaptic properties are specified and how single gene mutations associated with neurodevelopmental and psychiatric disorders might modify the operation of neuronal circuits and behaviour. In this Review, we first summarize insights into Neurexin function obtained from various model organisms. We then discuss the mechanisms and logic of the cell type-specific regulation of Neurexin isoforms, in particular at the level of alternative mRNA splicing. Finally, we propose a conceptual framework for how combinations of synaptic protein isoforms act as 'senders' and 'readers' to instruct synapse formation and the acquisition of cell type-specific and synapse-specific functional properties.
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Gandini MA, Zamponi GW. Voltage‐gated calcium channel nanodomains: molecular composition and function. FEBS J 2021; 289:614-633. [DOI: 10.1111/febs.15759] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Maria A. Gandini
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
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Abstract
Herein, I intend to capture highlights shared with my academic and research colleagues over the 60 years I devoted initially to my graduate and postdoctoral training and then to academic endeavors starting as an assistant professor in a new medical school at the University of California, San Diego (UCSD). During this period, the Department of Pharmacology emerged from a division within the Department of Medicine to become the first basic science department, solely within the School of Medicine at UCSD in 1979. As part of the school's plans to reorganize and to retain me at UCSD, I was appointed as founding chair. Some years later in 2002, faculty, led largely within the Department of Pharmacology and by practicing pharmacists within UCSD Healthcare, started the independent Skaggs School of Pharmacy and Pharmaceutical Sciences with a doctor of pharmacy (PharmD) program, where I served as the founding dean. My career pathway, from working at my family-owned pharmacy to chairing a department in a school of medicine and then becoming the dean of a school of pharmacy at a research-intensive, student-centered institution, involved some risky decisions. But the academic, curricular, and accreditation challenges posed were met by a cadre of creative faculty colleagues. I offer my experiences to individuals confronted with a multiplicity of real or imagined opportunities in academic health sciences, the related pharmaceutical industry, and government oversight agencies.
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Affiliation(s)
- Palmer Taylor
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, and School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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Comoletti D, Trobiani L, Chatonnet A, Bourne Y, Marchot P. Comparative mapping of selected structural determinants on the extracellular domains of cholinesterase-like cell-adhesion molecules. Neuropharmacology 2020; 184:108381. [PMID: 33166544 DOI: 10.1016/j.neuropharm.2020.108381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/10/2020] [Accepted: 10/29/2020] [Indexed: 11/18/2022]
Abstract
Cell adhesion generally involves formation of homophilic or heterophilic protein complexes between two cells to form transcellular junctions. Neural cell-adhesion members of the α/β-hydrolase fold superfamily of proteins use their extracellular or soluble cholinesterase-like domain to bind cognate partners across cell membranes, as illustrated by the neuroligins. These cell-adhesion molecules currently comprise the synaptic organizers neuroligins found in all animal phyla, along with three proteins found only in invertebrates: the guidance molecule neurotactin, the glia-specific gliotactin, and the basement membrane protein glutactin. Although these proteins share a cholinesterase-like fold, they lack one or more residues composing the catalytic triad responsible for the enzymatic activity of the cholinesterases. Conversely, they are found in various subcellular localisations and display specific disulfide bonding and N-glycosylation patterns, along with individual surface determinants possibly associated with recognition and binding of protein partners. Formation of non-covalent dimers typical of the cholinesterases is documented for mammalian neuroligins, yet whether invertebrate neuroligins and their neurotactin, gliotactin and glutactin relatives also form dimers in physiological conditions is unknown. Here we provide a brief overview of the localization, function, evolution, and conserved versus individual structural determinants of these cholinesterase-like cell-adhesion proteins. This article is part of the special issue entitled 'Acetylcholinesterase Inhibitors: From Bench to Bedside to Battlefield'.
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Affiliation(s)
- Davide Comoletti
- School of Biological Sciences, Victoria University of Wellington, Wellington, 6012, New Zealand; Child Health Institute of New Jersey, New Brunswick, NJ 08901, USA; Department of Neuroscience and Cell Biology Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ 08901, USA.
| | - Laura Trobiani
- School of Biological Sciences, Victoria University of Wellington, Wellington, 6012, New Zealand
| | - Arnaud Chatonnet
- Lab 'Dynamique Musculaire et Métabolisme', Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE) / Université Montpellier, Montpellier, France
| | - Yves Bourne
- Lab 'Architecture et Fonction des Macromolécules Biologiques (AFMB)', Centre National de la Recherche Scientifique (CNRS)/Aix-Marseille Univ, Faculté des Sciences - Campus Luminy, Marseille, France
| | - Pascale Marchot
- Lab 'Architecture et Fonction des Macromolécules Biologiques (AFMB)', Centre National de la Recherche Scientifique (CNRS)/Aix-Marseille Univ, Faculté des Sciences - Campus Luminy, Marseille, France.
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Trobiani L, Meringolo M, Diamanti T, Bourne Y, Marchot P, Martella G, Dini L, Pisani A, De Jaco A, Bonsi P. The neuroligins and the synaptic pathway in Autism Spectrum Disorder. Neurosci Biobehav Rev 2020; 119:37-51. [PMID: 32991906 DOI: 10.1016/j.neubiorev.2020.09.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/11/2020] [Accepted: 09/19/2020] [Indexed: 12/13/2022]
Abstract
The genetics underlying autism spectrum disorder (ASD) is complex and heterogeneous, and de novo variants are found in genes converging in functional biological processes. Neuronal communication, including trans-synaptic signaling involving two families of cell-adhesion proteins, the presynaptic neurexins and the postsynaptic neuroligins, is one of the most recurrently affected pathways in ASD. Given the role of these proteins in determining synaptic function, abnormal synaptic plasticity and failure to establish proper synaptic contacts might represent mechanisms underlying risk of ASD. More than 30 mutations have been found in the neuroligin genes. Most of the resulting residue substitutions map in the extracellular, cholinesterase-like domain of the protein, and impair protein folding and trafficking. Conversely, the stalk and intracellular domains are less affected. Accordingly, several genetic animal models of ASD have been generated, showing behavioral and synaptic alterations. The aim of this review is to discuss the current knowledge on ASD-linked mutations in the neuroligin proteins and their effect on synaptic function, in various brain areas and circuits.
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Affiliation(s)
- Laura Trobiani
- Dept. Biology and Biotechnology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Maria Meringolo
- Lab. Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143 Rome, Italy; Dept. Systems Medicine, University Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Tamara Diamanti
- Dept. Biology and Biotechnology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Yves Bourne
- Lab. "Architecture et Fonction des Macromolécules Biologiques", CNRS/Aix Marseille Univ, Faculté des Sciences - Campus Luminy, 163 Avenue de Luminy, 13288 Marseille cedex 09, France
| | - Pascale Marchot
- Lab. "Architecture et Fonction des Macromolécules Biologiques", CNRS/Aix Marseille Univ, Faculté des Sciences - Campus Luminy, 163 Avenue de Luminy, 13288 Marseille cedex 09, France
| | - Giuseppina Martella
- Lab. Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143 Rome, Italy; Dept. Systems Medicine, University Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Luciana Dini
- Dept. Biology and Biotechnology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Antonio Pisani
- Lab. Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143 Rome, Italy; Dept. Systems Medicine, University Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Antonella De Jaco
- Dept. Biology and Biotechnology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
| | - Paola Bonsi
- Lab. Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143 Rome, Italy.
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Ishizuka K, Yoshida T, Kawabata T, Imai A, Mori H, Kimura H, Inada T, Okahisa Y, Egawa J, Usami M, Kushima I, Morikawa M, Okada T, Ikeda M, Branko A, Mori D, Someya T, Iwata N, Ozaki N. Functional characterization of rare NRXN1 variants identified in autism spectrum disorders and schizophrenia. J Neurodev Disord 2020; 12:25. [PMID: 32942984 PMCID: PMC7496212 DOI: 10.1186/s11689-020-09325-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/28/2020] [Indexed: 11/10/2022] Open
Abstract
Background Rare genetic variants contribute to the etiology of both autism spectrum disorder (ASD) and schizophrenia (SCZ). Most genetic studies limit their focus to likely gene-disrupting mutations because they are relatively easier to interpret their effects on the gene product. Interpretation of missense variants is also informative to some pathophysiological mechanisms of these neurodevelopmental disorders; however, their contribution has not been elucidated because of relatively small effects. Therefore, we characterized missense variants detected in NRXN1, a well-known neurodevelopmental disease-causing gene, from individuals with ASD and SCZ. Methods To discover rare variants with large effect size and to evaluate their role in the shared etiopathophysiology of ASD and SCZ, we sequenced NRXN1 coding exons with a sample comprising 562 Japanese ASD and SCZ patients, followed by a genetic association analysis in 4273 unrelated individuals. Impact of each missense variant detected here on cell surface expression, interaction with NLGN1, and synaptogenic activity was analyzed using an in vitro functional assay and in silico three-dimensional (3D) structural modeling. Results Through mutation screening, we regarded three ultra-rare missense variants (T737M, D772G, and R856W), all of which affected the LNS4 domain of NRXN1α isoform, as disease-associated variants. Diagnosis of individuals with T737M, D772G, and R856W was 1ASD and 1SCZ, 1ASD, and 1SCZ, respectively. We observed the following phenotypic and functional burden caused by each variant. (i) D772G and R856W carriers had more serious social disabilities than T737M carriers. (ii) In vitro assay showed reduced cell surface expression of NRXN1α by D772G and R856W mutations. In vitro functional analysis showed decreased NRXN1α-NLGN1 interaction of T737M and D772G mutants. (iii) In silico 3D structural modeling indicated that T737M and D772G mutations could destabilize the rod-shaped structure of LNS2-LNS5 domains, and D772G and R856W could disturb N-glycan conformations for the transport signal. Conclusions The combined data suggest that missense variants in NRXN1 could be associated with phenotypes of neurodevelopmental disorders beyond the diagnosis of ASD and/or SCZ.
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Affiliation(s)
- Kanako Ishizuka
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Tomoyuki Yoshida
- Department of Molecular Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 9300194, Japan
| | - Takeshi Kawabata
- Institute for Protein Research, Osaka University, Osaka, 5650871, Japan
| | - Ayako Imai
- Department of Molecular Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 9300194, Japan
| | - Hisashi Mori
- Department of Molecular Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 9300194, Japan
| | - Hiroki Kimura
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Toshiya Inada
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Yuko Okahisa
- Department of Neuropsychiatry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 7008558, Japan
| | - Jun Egawa
- Department of Psychiatry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, 9518510, Japan
| | - Masahide Usami
- Department of Child and Adolescent Psychiatry, Kohnodai Hospital, National Center for Global Health and Medicine, Ichikawa, Chiba, 2728516, Japan
| | - Itaru Kushima
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Mako Morikawa
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Takashi Okada
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Masashi Ikeda
- Department of Psychiatry, Fujita Health University School of Medicine, Toyoake, Aichi, 4701192, Japan
| | - Aleksic Branko
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
| | - Daisuke Mori
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan. .,Brain and Mind Research Center, Nagoya University, Nagoya, Aichi, 4668550, Japan.
| | - Toshiyuki Someya
- Department of Psychiatry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, 9518510, Japan
| | - Nakao Iwata
- Department of Psychiatry, Fujita Health University School of Medicine, Toyoake, Aichi, 4701192, Japan
| | - Norio Ozaki
- Department of Psychiatry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 4668550, Japan
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Platsaki S, Zhou X, Pinan-Lucarré B, Delauzun V, Tu H, Mansuelle P, Fourquet P, Bourne Y, Bessereau JL, Marchot P. The Ig-like domain of Punctin/MADD-4 is the primary determinant for interaction with the ectodomain of neuroligin NLG-1. J Biol Chem 2020; 295:16267-16279. [PMID: 32928959 DOI: 10.1074/jbc.ra120.014591] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/02/2020] [Indexed: 02/01/2023] Open
Abstract
Punctin/MADD-4, a member of the ADAMTSL extracellular matrix protein family, was identified as an anterograde synaptic organizer in the nematode Caenorhabditis elegans. At GABAergic neuromuscular junctions, the short isoform MADD-4B binds the ectodomain of neuroligin NLG-1, itself a postsynaptic organizer of inhibitory synapses. To identify the molecular bases of their partnership, we generated recombinant forms of the two proteins and carried out a comprehensive biochemical and biophysical study of their interaction, complemented by an in vivo localization study. We show that spontaneous proteolysis of MADD-4B first generates a shorter N-MADD-4B form, which comprises four thrombospondin (TSP) domains and one Ig-like domain and binds NLG-1. A second processing event eliminates the C-terminal Ig-like domain along with the ability of N-MADD-4B to bind NLG-1. These data identify the Ig-like domain as the primary determinant for N-MADD-4B interaction with NLG-1 in vitro We further demonstrate in vivo that this Ig-like domain is essential, albeit not sufficient per se, for efficient recruitment of GABAA receptors at GABAergic synapses in C. elegans The interaction of N-MADD-4B with NLG-1 is also disrupted by heparin, used as a surrogate for the extracellular matrix component, heparan sulfate. High-affinity binding of heparin/heparan sulfate to the Ig-like domain may proceed from surface charge complementarity, as suggested by homology three-dimensional modeling. These data point to N-MADD-4B processing and cell-surface proteoglycan binding as two possible mechanisms to regulate the interaction between MADD-4B and NLG-1 at GABAergic synapses.
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Affiliation(s)
- Semeli Platsaki
- CNRS/Aix-Marseille Univ, Laboratory "Architecture et Fonction des Macromolécules Biologiques" (AFMB), Marseille, France
| | - Xin Zhou
- Univ Lyon/Univ Claude Bernard Lyon 1/CNRS/INSERM, Institut NeuroMyoGène (INMG), Lyon, France
| | - Bérangère Pinan-Lucarré
- Univ Lyon/Univ Claude Bernard Lyon 1/CNRS/INSERM, Institut NeuroMyoGène (INMG), Lyon, France
| | - Vincent Delauzun
- CNRS/Aix-Marseille Univ, Laboratory "Architecture et Fonction des Macromolécules Biologiques" (AFMB), Marseille, France
| | - Haijun Tu
- Univ Lyon/Univ Claude Bernard Lyon 1/CNRS/INSERM, Institut NeuroMyoGène (INMG), Lyon, France
| | - Pascal Mansuelle
- CNRS/Aix-Marseille Univ, Institut de Microbiologie de la Méditerranée (IMM), Marseille Proteomics (MaP), Marseille, France
| | - Patrick Fourquet
- Aix-Marseille Univ/INSERM/CNRS, Institut Paoli-Calmettes, Centre de Recherche en Cancérologie de Marseille (CRCM), Marseille Proteomics (MaP), Marseille, France
| | - Yves Bourne
- CNRS/Aix-Marseille Univ, Laboratory "Architecture et Fonction des Macromolécules Biologiques" (AFMB), Marseille, France
| | - Jean-Louis Bessereau
- Univ Lyon/Univ Claude Bernard Lyon 1/CNRS/INSERM, Institut NeuroMyoGène (INMG), Lyon, France
| | - Pascale Marchot
- CNRS/Aix-Marseille Univ, Laboratory "Architecture et Fonction des Macromolécules Biologiques" (AFMB), Marseille, France.
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Taylor CP, Harris EW. Analgesia with Gabapentin and Pregabalin May Involve N-Methyl-d-Aspartate Receptors, Neurexins, and Thrombospondins. J Pharmacol Exp Ther 2020; 374:161-174. [DOI: 10.1124/jpet.120.266056] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/17/2020] [Indexed: 11/22/2022] Open
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Wilson SC, White KI, Zhou Q, Pfuetzner RA, Choi UB, Südhof TC, Brunger AT. Structures of neurexophilin-neurexin complexes reveal a regulatory mechanism of alternative splicing. EMBO J 2019; 38:e101603. [PMID: 31566781 PMCID: PMC6856630 DOI: 10.15252/embj.2019101603] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 01/09/2023] Open
Abstract
Neurexins are presynaptic, cell-adhesion molecules that specify the functional properties of synapses via interactions with trans-synaptic ligands. Neurexins are extensively alternatively spliced at six canonical sites that regulate multifarious ligand interactions, but the structural mechanisms underlying alternative splicing-dependent neurexin regulation are largely unknown. Here, we determined high-resolution structures of the complex of neurexophilin-1 and the second laminin/neurexin/sex-hormone-binding globulin domain (LNS2) of neurexin-1 and examined how alternative splicing at splice site #2 (SS2) regulates the complex. Our data reveal a unique, extensive, neurexophilin-neurexin binding interface that extends the jelly-roll β-sandwich of LNS2 of neurexin-1 into neurexophilin-1. The SS2A insert of LNS2 augments this interface, increasing the binding affinity of LNS2 for neurexophilin-1. Taken together, our data reveal an unexpected architecture of neurexophilin-neurexin complexes that accounts for the modulation of binding by alternative splicing, which in turn regulates the competition of neurexophilin for neurexin binding with other ligands.
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Affiliation(s)
- Steven C Wilson
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
| | - K Ian White
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
| | - Qiangjun Zhou
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
| | - Richard A Pfuetzner
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
| | - Ucheor B Choi
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
| | - Thomas C Südhof
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
- Howard Hughes Medical InstituteStanford UniversityStanfordCAUSA
| | - Axel T Brunger
- Department of Molecular and Cellular PhysiologyStanford UniversityStanfordCAUSA
- Howard Hughes Medical InstituteStanford UniversityStanfordCAUSA
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13
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Modeling a Neurexin-3α Human Mutation in Mouse Neurons Identifies a Novel Role in the Regulation of Transsynaptic Signaling and Neurotransmitter Release at Excitatory Synapses. J Neurosci 2019; 39:9065-9082. [PMID: 31578233 DOI: 10.1523/jneurosci.1261-19.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/13/2019] [Accepted: 09/22/2019] [Indexed: 12/27/2022] Open
Abstract
Presynaptic α-neurexins are highly expressed and more frequently linked to neuropsychiatric and neurodevelopmental disorders than β-neurexins. However, how extracellular sequences specific to α-neurexins enable synaptic transmission is poorly understood. We identified a mutation in an extracellular region of neurexin-3α (A687T), located in a region conserved among α-neurexins and throughout vertebrate evolution, in a patient diagnosed with profound intellectual disability and epilepsy. We systematically interrogated this mutation using a knockdown-replacement approach, and discovered that the A687T mutation enhanced presynaptic morphology and increased two critical presynaptic parameters: (1) presynaptic release probability, and (2) the size of the readily releasable pool exclusively at excitatory synapses in mixed sex primary mouse hippocampal cultures. Introduction of the mutation in vivo and subsequent analysis in ex vivo brain slices made from male and female mice revealed a significant increase in excitatory presynaptic neurotransmission that occluded presynaptic but not postsynaptic LTP. Mechanistically, neurexin-3αA687T enhanced binding to LRRTM2 without altering binding to postsynaptic neuroligin-1. Thus, neurexin-3αA687T unexpectedly produced the first neurexin presynaptic gain-of-function phenotype and revealed unanticipated novel insights into how α-neurexin extracellular sequences govern both transsynaptic adhesion and presynaptic neurotransmitter release.SIGNIFICANCE STATEMENT Despite decades of scientific scrutiny, how precise α-neurexin extracellular sequences control synapse function remains enigmatic. One largely unpursued avenue to identify the role of precise extracellular sequences is the interrogation of naturally occurring missense mutations. Here, we identified a neurexin-3α missense mutation in a compound heterozygous patient diagnosed with profound intellectual disability and epilepsy and systematically interrogated this mutation. Using in vitro and in vivo molecular replacement, electrophysiology, electron microscopy, and structure-function analyses, we reveal a novel role for neurexin-3α, unanticipated based on α-neurexin knock-out models, in controlling presynaptic morphology and neurotransmitter release at excitatory synapses. Our findings represent the first neurexin gain-of-function phenotype and provide new fundamentally important insight into the synaptic biology of α-neurexins.
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14
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Hu Z, Xiao X, Zhang Z, Li M. Genetic insights and neurobiological implications from NRXN1 in neuropsychiatric disorders. Mol Psychiatry 2019; 24:1400-1414. [PMID: 31138894 DOI: 10.1038/s41380-019-0438-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/31/2019] [Accepted: 04/29/2019] [Indexed: 02/08/2023]
Abstract
Many neuropsychiatric and neurodevelopmental disorders commonly share genetic risk factors. To date, the mechanisms driving the pathogenesis of these disorders, particularly how genetic variations affect the function of risk genes and contribute to disease symptoms, remain largely unknown. Neurexins are a family of synaptic adhesion molecules, which play important roles in the formation and establishment of synaptic structure, as well as maintenance of synaptic function. Accumulating genomic findings reveal that genetic variations within genes encoding neurexins are associated with a variety of psychiatric conditions such as schizophrenia, autism spectrum disorder, and some developmental abnormalities. In this review, we focus on NRXN1, one of the most compelling psychiatric risk genes of the neurexin family. We performed a comprehensive survey and analysis of current genetic and molecular data including both common and rare alleles within NRXN1 associated with psychiatric illnesses, thus providing insights into the genetic risk conferred by NRXN1. We also summarized the neurobiological evidences, supporting the function of NRXN1 and its protein products in synaptic formation, organization, transmission and plasticity, as well as disease-relevant behaviors, and assessed the mechanistic link between the mutations of NRXN1 and synaptic and behavioral pathology in neuropsychiatric disorders.
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Affiliation(s)
- Zhonghua Hu
- Institute of Molecular Precision Medicine and Hunan Key Laboratory of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China. .,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China. .,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China. .,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, Hunan, China. .,Department of Psychiatry, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China. .,National Clinical Research Center on Mental Disorders, Changsha, Hunan, China.
| | - Xiao Xiao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Zhuohua Zhang
- Institute of Molecular Precision Medicine and Hunan Key Laboratory of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Ming Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China. .,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.
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15
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Zambonino M, Pereira P. The structure of Neurexin 1α (n1α) and its role as synaptic organizer. BIONATURA 2019. [DOI: 10.21931/rb/2019.04.02.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
α - and b-neurexins (NRXNs) are transmembrane adhesion protein complexes localized in presynaptic membranes into neurons and interact with the postsynaptic neuroligins (NLGNs). Our findings indicate that the neurexin 1α (n1α) is a synaptic organizer that directs postsynaptic development in neurons, evidenced in GABAergic neurons and trials with Knock-out Mice. Also, the interactions between hypervariable surfaces of n1α and ligands (neurexophilin, a-dystroglycan, and GABAA) promotes a proper protein-binding recognition, and consequently, a better synaptic adhesion.
There is a direct relationship between mental disorders and the n1α assemblage because NRXN1 gene encodes for n1α proteins which are involved in the transmission of information into the brain. For this reason, damage in this complex-protein or some neurexin gene variations causes pathological abnormalities and neuropsychiatric diseases such as schizophrenia, autism spectrum disorders, and intellectual disabilities.
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Affiliation(s)
- Marjorie Zambonino
- Universidad de Investigación de Tecnología Experimental Yachay Tech 1,2School of Biological and Applied - Biomedical Engineering Department
| | - Pamela Pereira
- Universidad de Investigación de Tecnología Experimental Yachay Tech 1,2School of Biological and Applied - Biomedical Engineering Department
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16
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de Vrij FM, Bouwkamp CG, Gunhanlar N, Shpak G, Lendemeijer B, Baghdadi M, Gopalakrishna S, Ghazvini M, Li TM, Quadri M, Olgiati S, Breedveld GJ, Coesmans M, Mientjes E, de Wit T, Verheijen FW, Beverloo HB, Cohen D, Kok RM, Bakker PR, Nijburg A, Spijker AT, Haffmans PMJ, Hoencamp E, Bergink V, Vorstman JA, Wu T, Olde Loohuis LM, Amin N, Langen CD, Hofman A, Hoogendijk WJ, van Duijn CM, Ikram MA, Vernooij MW, Tiemeier H, Uitterlinden AG, Elgersma Y, Distel B, Gribnau J, White T, Bonifati V, Kushner SA. Candidate CSPG4 mutations and induced pluripotent stem cell modeling implicate oligodendrocyte progenitor cell dysfunction in familial schizophrenia. Mol Psychiatry 2019; 24:757-771. [PMID: 29302076 PMCID: PMC6755981 DOI: 10.1038/s41380-017-0004-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 09/24/2017] [Accepted: 11/01/2017] [Indexed: 01/09/2023]
Abstract
Schizophrenia is highly heritable, yet its underlying pathophysiology remains largely unknown. Among the most well-replicated findings in neurobiological studies of schizophrenia are deficits in myelination and white matter integrity; however, direct etiological genetic and cellular evidence has thus far been lacking. Here, we implement a family-based approach for genetic discovery in schizophrenia combined with functional analysis using induced pluripotent stem cells (iPSCs). We observed familial segregation of two rare missense mutations in Chondroitin Sulfate Proteoglycan 4 (CSPG4) (c.391G > A [p.A131T], MAF 7.79 × 10-5 and c.2702T > G [p.V901G], MAF 2.51 × 10-3). The CSPG4A131T mutation was absent from the Swedish Schizophrenia Exome Sequencing Study (2536 cases, 2543 controls), while the CSPG4V901G mutation was nominally enriched in cases (11 cases vs. 3 controls, P = 0.026, OR 3.77, 95% CI 1.05-13.52). CSPG4/NG2 is a hallmark protein of oligodendrocyte progenitor cells (OPCs). iPSC-derived OPCs from CSPG4A131T mutation carriers exhibited abnormal post-translational processing (P = 0.029), subcellular localization of mutant NG2 (P = 0.007), as well as aberrant cellular morphology (P = 3.0 × 10-8), viability (P = 8.9 × 10-7), and myelination potential (P = 0.038). Moreover, transfection of healthy non-carrier sibling OPCs confirmed a pathogenic effect on cell survival of both the CSPG4A131T (P = 0.006) and CSPG4V901G (P = 3.4 × 10-4) mutations. Finally, in vivo diffusion tensor imaging of CSPG4A131T mutation carriers demonstrated a reduction of brain white matter integrity compared to unaffected sibling and matched general population controls (P = 2.2 × 10-5). Together, our findings provide a convergence of genetic and functional evidence to implicate OPC dysfunction as a candidate pathophysiological mechanism of familial schizophrenia.
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Affiliation(s)
- Femke M de Vrij
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Christian G Bouwkamp
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Nilhan Gunhanlar
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Guy Shpak
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Bas Lendemeijer
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Maarouf Baghdadi
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Mehrnaz Ghazvini
- Department of Developmental Biology, and Erasmus MC iPS Facility, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Tracy M Li
- Department of Developmental Biology, and Erasmus MC iPS Facility, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Marialuisa Quadri
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Simone Olgiati
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Guido J Breedveld
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Michiel Coesmans
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
- Delta Psychiatric Center, Poortugaal, The Netherlands
| | - Edwin Mientjes
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
- ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ton de Wit
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Frans W Verheijen
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - H Berna Beverloo
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Dan Cohen
- Mental Health Care Organization North-Holland North, Heerhugowaard, The Netherlands
| | - Rob M Kok
- Parnassia Psychiatric Institute, The Hague, The Netherlands
| | - P Roberto Bakker
- Department of Psychiatry and Psychology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
- Psychiatric Center GGZ Centraal, Amersfoort, The Netherlands
| | - Aviva Nijburg
- Parnassia Psychiatric Institute, The Hague, The Netherlands
| | | | - P M Judith Haffmans
- Faculty of Social and Behavioral Sciences Clinical, Health and Neuro Psychology, Department of Affective Disorders, PsyQ, Leiden University, Leiden, The Netherlands
| | - Erik Hoencamp
- Parnassia Psychiatric Institute, The Hague, The Netherlands
- Institute of Psychology, Leiden University, Leiden, The Netherlands
| | - Veerle Bergink
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Jacob A Vorstman
- Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
- Department of Psychiatry, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
- Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Timothy Wu
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Loes M Olde Loohuis
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Najaf Amin
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Carolyn D Langen
- Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Medical Informatics, Erasmus Medical Center, Rotterdam, The Netherlands
- Biomedical Imaging Group Rotterdam, Departments of Radiology & Medical Informatics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Albert Hofman
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Witte J Hoogendijk
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - M Arfan Ikram
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Meike W Vernooij
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Henning Tiemeier
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Medical Informatics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - André G Uitterlinden
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ype Elgersma
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
- ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ben Distel
- Department of Medical Biochemistry, Academic Medical Centre, Amsterdam, The Netherlands
| | - Joost Gribnau
- Department of Developmental Biology, and Erasmus MC iPS Facility, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Tonya White
- Department of Medical Informatics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Vincenzo Bonifati
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Steven A Kushner
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands.
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17
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Neurexins - versatile molecular platforms in the synaptic cleft. Curr Opin Struct Biol 2019; 54:112-121. [PMID: 30831539 DOI: 10.1016/j.sbi.2019.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/22/2019] [Accepted: 01/24/2019] [Indexed: 01/05/2023]
Abstract
Neurexins constitute a large family of synaptic organizers. Their extracellular domains protrude into the synaptic cleft where they can form transsynaptic bridges with different partners. A unique constellation of structural elements within their ectodomains enables neurexins to create molecular platforms within the synaptic cleft that permit a large portfolio of partners to be recruited, assembled and their interactions to be dynamically regulated. Neurexins and their partners are implicated in neuropsychiatric diseases including autism spectrum disorder and schizophrenia. Detailed understanding of the mechanisms that underlie neurexin interactions may in future guide the design of tools to manipulate synaptic connections and their function, in particular those involved in the pathogenesis of neuropsychiatric disease.
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18
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Chamma I, Sainlos M, Thoumine O. Biophysical mechanisms underlying the membrane trafficking of synaptic adhesion molecules. Neuropharmacology 2019; 169:107555. [PMID: 30831159 DOI: 10.1016/j.neuropharm.2019.02.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 02/14/2019] [Accepted: 02/27/2019] [Indexed: 01/13/2023]
Abstract
Adhesion proteins play crucial roles at synapses, not only by providing a physical trans-synaptic linkage between axonal and dendritic membranes, but also by connecting to functional elements including the pre-synaptic neurotransmitter release machinery and post-synaptic receptors. To mediate these functions, adhesion proteins must be organized on the neuronal surface in a precise and controlled manner. Recent studies have started to describe the mobility, nanoscale organization, and turnover rate of key synaptic adhesion molecules including cadherins, neurexins, neuroligins, SynCAMs, and LRRTMs, and show that some of these proteins are highly mobile in the plasma membrane while others are confined at sub-synaptic compartments, providing evidence for different regulatory pathways. In this review article, we provide a biophysical view of the diffusional trapping of adhesion molecules at synapses, involving both extracellular and intracellular protein interactions. We review the methodology underlying these measurements, including biomimetic systems with purified adhesion proteins, means to perturb protein expression or function, single molecule imaging in cultured neurons, and analytical models to interpret the data. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Ingrid Chamma
- Univ. Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France
| | - Matthieu Sainlos
- Univ. Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France
| | - Olivier Thoumine
- Univ. Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000, Bordeaux, France.
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19
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Liu J, Misra A, Reddy MVVVS, White MA, Ren G, Rudenko G. Structural Plasticity of Neurexin 1α: Implications for its Role as Synaptic Organizer. J Mol Biol 2018; 430:4325-4343. [PMID: 30193986 PMCID: PMC6223652 DOI: 10.1016/j.jmb.2018.08.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 11/24/2022]
Abstract
α-Neurexins are synaptic organizing molecules implicated in neuropsychiatric disorders. They bind and arrange an array of different partners in the synaptic cleft. The extracellular region of neurexin 1α (n1α) contains six LNS domains (L1-L6) interspersed by three Egf-like repeats. N1α must encode highly evolved structure-function relationships in order to fit into the narrow confines of the synaptic cleft, and also recruit its large, membrane-bound partners. Internal molecular flexibility could provide a solution; however, it is challenging to delineate because currently no structural methods permit high-resolution structure determination of large, flexible, multi-domain protein molecules. To investigate the structural plasticity of n1α, in particular the conformation of domains that carry validated binding sites for different protein partners, we used a panel of structural techniques. Individual particle electron tomography revealed that the N-terminally and C-terminally tethered domains, L1 and L6, have a surprisingly limited range of conformational freedom with respect to the linear central core containing L2 through L5. A 2.8-Å crystal structure revealed an unexpected arrangement of the L2 and L3 domains. Small-angle X-ray scattering and electron tomography indicated that incorporation of the alternative splice insert SS6 relieves the restricted conformational freedom between L5 and L6, suggesting that SS6 may work as a molecular toggle. The architecture of n1α thus encodes a combination of rigid and flexibly tethered domains that are uniquely poised to work together to promote its organizing function in the synaptic cleft, and may permit allosterically regulated and/or concerted protein partner binding.
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Affiliation(s)
- Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Anurag Misra
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - M V V V Sekhar Reddy
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Mark Andrew White
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Gabby Rudenko
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
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20
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A Missense Variant at the Nrxn3 Locus Enhances Empathy Fear in the Mouse. Neuron 2018; 98:588-601.e5. [DOI: 10.1016/j.neuron.2018.03.041] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/19/2018] [Accepted: 03/22/2018] [Indexed: 12/30/2022]
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21
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Bourne Y, Marchot P. Hot Spots for Protein Partnerships at the Surface of Cholinesterases and Related α/β Hydrolase Fold Proteins or Domains-A Structural Perspective. Molecules 2017; 23:molecules23010035. [PMID: 29295471 PMCID: PMC5943944 DOI: 10.3390/molecules23010035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 12/12/2022] Open
Abstract
The hydrolytic enzymes acetyl- and butyryl-cholinesterase, the cell adhesion molecules neuroligins, and the hormonogenic macromolecule thyroglobulin are a few of the many members of the α/β hydrolase fold superfamily of proteins. Despite their distinctive functions, their canonical subunits, with a molecular surface area of ~20,000 Å2, they share binding patches and determinants for forming homodimers and for accommodating structural subunits or protein partners. Several of these surface regions of high functional relevance have been mapped through structural or mutational studies, while others have been proposed based on biochemical data or molecular docking studies. Here, we review these binding interfaces and emphasize their specificity versus potentially multifunctional character.
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Affiliation(s)
- Yves Bourne
- Centre National de la Recherche Scientifique, Aix-Marseille Université, "Architecture et Fonction des Macromolécules Biologiques" Laboratory, 13288 Marseille, France.
| | - Pascale Marchot
- Centre National de la Recherche Scientifique, Aix-Marseille Université, "Architecture et Fonction des Macromolécules Biologiques" Laboratory, 13288 Marseille, France.
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22
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Südhof TC. Synaptic Neurexin Complexes: A Molecular Code for the Logic of Neural Circuits. Cell 2017; 171:745-769. [PMID: 29100073 DOI: 10.1016/j.cell.2017.10.024] [Citation(s) in RCA: 474] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/04/2017] [Accepted: 10/15/2017] [Indexed: 10/18/2022]
Abstract
Synapses are specialized junctions between neurons in brain that transmit and compute information, thereby connecting neurons into millions of overlapping and interdigitated neural circuits. Here, we posit that the establishment, properties, and dynamics of synapses are governed by a molecular logic that is controlled by diverse trans-synaptic signaling molecules. Neurexins, expressed in thousands of alternatively spliced isoforms, are central components of this dynamic code. Presynaptic neurexins regulate synapse properties via differential binding to multifarious postsynaptic ligands, such as neuroligins, cerebellin/GluD complexes, and latrophilins, thereby shaping the input/output relations of their resident neural circuits. Mutations in genes encoding neurexins and their ligands are associated with diverse neuropsychiatric disorders, especially schizophrenia, autism, and Tourette syndrome. Thus, neurexins nucleate an overall trans-synaptic signaling network that controls synapse properties, which thereby determines the precise responses of synapses to spike patterns in a neuron and circuit and which is vulnerable to impairments in neuropsychiatric disorders.
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Affiliation(s)
- Thomas C Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, CA 94305-5453, USA.
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23
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Brito-Moreira J, Lourenco MV, Oliveira MM, Ribeiro FC, Ledo JH, Diniz LP, Vital JFS, Magdesian MH, Melo HM, Barros-Aragão F, de Souza JM, Alves-Leon SV, Gomes FCA, Clarke JR, Figueiredo CP, De Felice FG, Ferreira ST. Interaction of amyloid-β (Aβ) oligomers with neurexin 2α and neuroligin 1 mediates synapse damage and memory loss in mice. J Biol Chem 2017; 292:7327-7337. [PMID: 28283575 DOI: 10.1074/jbc.m116.761189] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 02/26/2017] [Indexed: 11/06/2022] Open
Abstract
Brain accumulation of the amyloid-β protein (Aβ) and synapse loss are neuropathological hallmarks of Alzheimer disease (AD). Aβ oligomers (AβOs) are synaptotoxins that build up in the brains of patients and are thought to contribute to memory impairment in AD. Thus, identification of novel synaptic components that are targeted by AβOs may contribute to the elucidation of disease-relevant mechanisms. Trans-synaptic interactions between neurexins (Nrxs) and neuroligins (NLs) are essential for synapse structure, stability, and function, and reduced NL levels have been associated recently with AD. Here we investigated whether the interaction of AβOs with Nrxs or NLs mediates synapse damage and cognitive impairment in AD models. We found that AβOs interact with different isoforms of Nrx and NL, including Nrx2α and NL1. Anti-Nrx2α and anti-NL1 antibodies reduced AβO binding to hippocampal neurons and prevented AβO-induced neuronal oxidative stress and synapse loss. Anti-Nrx2α and anti-NL1 antibodies further blocked memory impairment induced by AβOs in mice. The results indicate that Nrx2α and NL1 are targets of AβOs and that prevention of this interaction reduces the deleterious impact of AβOs on synapses and cognition. Identification of Nrx2α and NL1 as synaptic components that interact with AβOs may pave the way for development of novel approaches aimed at halting synapse failure and cognitive loss in AD.
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Affiliation(s)
| | - Mychael V Lourenco
- From the Institute of Medical Biochemistry Leopoldo de Meis.,Institute of Biophysics Carlos Chagas Filho
| | - Mauricio M Oliveira
- From the Institute of Medical Biochemistry Leopoldo de Meis.,Institute of Biophysics Carlos Chagas Filho
| | - Felipe C Ribeiro
- From the Institute of Medical Biochemistry Leopoldo de Meis.,Institute of Biophysics Carlos Chagas Filho
| | | | | | | | | | - Helen M Melo
- From the Institute of Medical Biochemistry Leopoldo de Meis
| | | | - Jorge M de Souza
- Division of Neurosurgery and Division of Neurology/Epilepsy Program, Clementino Fraga Filho University Hospital, and
| | - Soniza V Alves-Leon
- Division of Neurosurgery and Division of Neurology/Epilepsy Program, Clementino Fraga Filho University Hospital, and
| | | | - Julia R Clarke
- School of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil and
| | - Cláudia P Figueiredo
- School of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil and
| | - Fernanda G De Felice
- From the Institute of Medical Biochemistry Leopoldo de Meis.,the Centre for Neuroscience Studies, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Sergio T Ferreira
- From the Institute of Medical Biochemistry Leopoldo de Meis, .,Institute of Biophysics Carlos Chagas Filho
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24
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Cheng S, Seven AB, Wang J, Skiniotis G, Özkan E. Conformational Plasticity in the Transsynaptic Neurexin-Cerebellin-Glutamate Receptor Adhesion Complex. Structure 2016; 24:2163-2173. [PMID: 27926833 PMCID: PMC5149402 DOI: 10.1016/j.str.2016.11.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 10/11/2016] [Accepted: 11/07/2016] [Indexed: 01/07/2023]
Abstract
Synaptic specificity is a defining property of neural networks. In the cerebellum, synapses between parallel fiber neurons and Purkinje cells are specified by the simultaneous interactions of secreted protein cerebellin with pre-synaptic neurexin and post-synaptic delta-type glutamate receptors (GluD). Here, we determined the crystal structures of the trimeric C1q-like domain of rat cerebellin-1, and the first complete ectodomain of a GluD, rat GluD2. Cerebellin binds to the LNS6 domain of α- and β-neurexin-1 through a high-affinity interaction that involves its highly flexible N-terminal domain. In contrast, we show that the interaction of cerebellin with isolated GluD2 ectodomain is low affinity, which is not simply an outcome of lost avidity when compared with binding with a tetrameric full-length receptor. Rather, high-affinity capture of cerebellin by post-synaptic terminals is likely controlled by long-distance regulation within this transsynaptic complex. Altogether, our results suggest unusual conformational flexibility within all components of the complex.
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Affiliation(s)
- Shouqiang Cheng
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Alpay B Seven
- Department of Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jing Wang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Georgios Skiniotis
- Department of Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.
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25
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Lu Z, Reddy MVVVS, Liu J, Kalichava A, Liu J, Zhang L, Chen F, Wang Y, Holthauzen LMF, White MA, Seshadrinathan S, Zhong X, Ren G, Rudenko G. Molecular Architecture of Contactin-associated Protein-like 2 (CNTNAP2) and Its Interaction with Contactin 2 (CNTN2). J Biol Chem 2016; 291:24133-24147. [PMID: 27621318 DOI: 10.1074/jbc.m116.748236] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/02/2016] [Indexed: 11/06/2022] Open
Abstract
Contactin-associated protein-like 2 (CNTNAP2) is a large multidomain neuronal adhesion molecule implicated in a number of neurological disorders, including epilepsy, schizophrenia, autism spectrum disorder, intellectual disability, and language delay. We reveal here by electron microscopy that the architecture of CNTNAP2 is composed of a large, medium, and small lobe that flex with respect to each other. Using epitope labeling and fragments, we assign the F58C, L1, and L2 domains to the large lobe, the FBG and L3 domains to the middle lobe, and the L4 domain to the small lobe of the CNTNAP2 molecular envelope. Our data reveal that CNTNAP2 has a very different architecture compared with neurexin 1α, a fellow member of the neurexin superfamily and a prototype, suggesting that CNTNAP2 uses a different strategy to integrate into the synaptic protein network. We show that the ectodomains of CNTNAP2 and contactin 2 (CNTN2) bind directly and specifically, with low nanomolar affinity. We show further that mutations in CNTNAP2 implicated in autism spectrum disorder are not segregated but are distributed over the whole ectodomain. The molecular shape and dimensions of CNTNAP2 place constraints on how CNTNAP2 integrates in the cleft of axo-glial and neuronal contact sites and how it functions as an organizing and adhesive molecule.
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Affiliation(s)
- Zhuoyang Lu
- From the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720.,the Center for Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - M V V V Sekhar Reddy
- the Department of Pharmacology and Toxicology.,the Sealy Center for Structural Biology and Molecular Biophysics and
| | - Jianfang Liu
- From the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Ana Kalichava
- the Department of Pharmacology and Toxicology.,the Sealy Center for Structural Biology and Molecular Biophysics and
| | - Jiankang Liu
- the Center for Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Lei Zhang
- From the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Fang Chen
- the University of Michigan, Ann Arbor, Michigan 48109
| | - Yun Wang
- the University of Michigan, Ann Arbor, Michigan 48109
| | | | - Mark A White
- the Sealy Center for Structural Biology and Molecular Biophysics and.,the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555, and
| | - Suchithra Seshadrinathan
- the Department of Pharmacology and Toxicology.,the Sealy Center for Structural Biology and Molecular Biophysics and
| | - Xiaoying Zhong
- the Department of Pharmacology and Toxicology.,the Sealy Center for Structural Biology and Molecular Biophysics and
| | - Gang Ren
- From the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720,
| | - Gabby Rudenko
- the Department of Pharmacology and Toxicology, .,the Sealy Center for Structural Biology and Molecular Biophysics and
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26
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Nikolaienko RM, Hammel M, Dubreuil V, Zalmai R, Hall DR, Mehzabeen N, Karuppan SJ, Harroch S, Stella SL, Bouyain S. Structural Basis for Interactions Between Contactin Family Members and Protein-tyrosine Phosphatase Receptor Type G in Neural Tissues. J Biol Chem 2016; 291:21335-21349. [PMID: 27539848 DOI: 10.1074/jbc.m116.742163] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/10/2016] [Indexed: 01/06/2023] Open
Abstract
Protein-tyrosine phosphatase receptor type G (RPTPγ/PTPRG) interacts in vitro with contactin-3-6 (CNTN3-6), a group of glycophosphatidylinositol-anchored cell adhesion molecules involved in the wiring of the nervous system. In addition to PTPRG, CNTNs associate with multiple transmembrane proteins and signal inside the cell via cis-binding partners to alleviate the absence of an intracellular region. Here, we use comprehensive biochemical and structural analyses to demonstrate that PTPRG·CNTN3-6 complexes share similar binding affinities and a conserved arrangement. Furthermore, as a first step to identifying PTPRG·CNTN complexes in vivo, we found that PTPRG and CNTN3 associate in the outer segments of mouse rod photoreceptor cells. In particular, PTPRG and CNTN3 form cis-complexes at the surface of photoreceptors yet interact in trans when expressed on the surfaces of apposing cells. Further structural analyses suggest that all CNTN ectodomains adopt a bent conformation and might lie parallel to the cell surface to accommodate these cis and trans binding modes. Taken together, these studies identify a PTPRG·CNTN complex in vivo and provide novel insights into PTPRG- and CNTN-mediated signaling.
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Affiliation(s)
- Roman M Nikolaienko
- From the Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - Michal Hammel
- the Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Véronique Dubreuil
- the Départment de Neuroscience, Institut Pasteur de Paris, 25-28 Rue du Dr. Roux, 75624 Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216, CNRS, Paris, France, and
| | - Rana Zalmai
- From the Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - David R Hall
- From the Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - Nurjahan Mehzabeen
- From the Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - Sebastian J Karuppan
- From the Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - Sheila Harroch
- Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216, CNRS, Paris, France, and
| | - Salvatore L Stella
- the Department of Basic Medical Science, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri 64108
| | - Samuel Bouyain
- From the Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110,
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27
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Rubio-Marrero EN, Vincelli G, Jeffries CM, Shaikh TR, Pakos IS, Ranaivoson FM, von Daake S, Demeler B, De Jaco A, Perkins G, Ellisman MH, Trewhella J, Comoletti D. Structural Characterization of the Extracellular Domain of CASPR2 and Insights into Its Association with the Novel Ligand Contactin1. J Biol Chem 2016; 291:5788-5802. [PMID: 26721881 PMCID: PMC4786715 DOI: 10.1074/jbc.m115.705681] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/28/2015] [Indexed: 01/06/2023] Open
Abstract
Contactin-associated protein-like 2 (CNTNAP2) encodes for CASPR2, a multidomain single transmembrane protein belonging to the neurexin superfamily that has been implicated in a broad range of human phenotypes including autism and language impairment. Using a combination of biophysical techniques, including small angle x-ray scattering, single particle electron microscopy, analytical ultracentrifugation, and bio-layer interferometry, we present novel structural and functional data that relate the architecture of the extracellular domain of CASPR2 to a previously unknown ligand, Contactin1 (CNTN1). Structurally, CASPR2 is highly glycosylated and has an overall compact architecture. Functionally, we show that CASPR2 associates with micromolar affinity with CNTN1 but, under the same conditions, it does not interact with any of the other members of the contactin family. Moreover, by using dissociated hippocampal neurons we show that microbeads loaded with CASPR2, but not with a deletion mutant, co-localize with transfected CNTN1, suggesting that CNTN1 is an endogenous ligand for CASPR2. These data provide novel insights into the structure and function of CASPR2, suggesting a complex role of CASPR2 in the nervous system.
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Affiliation(s)
- Eva N Rubio-Marrero
- From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and
| | - Gabriele Vincelli
- From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and
| | - Cy M Jeffries
- the School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
| | - Tanvir R Shaikh
- the Structural Biology Programme, Central European Institute of Technology, Masaryk University, 62500 Brno, Czech Republic
| | - Irene S Pakos
- From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and
| | - Fanomezana M Ranaivoson
- From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and
| | - Sventja von Daake
- From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and
| | - Borries Demeler
- the Department of Biochemistry, The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Antonella De Jaco
- the Department of Biology and Biotechnologies "Charles Darwin" and Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy 00185
| | - Guy Perkins
- the National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, California 92093, and
| | - Mark H Ellisman
- the National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, California 92093, and
| | - Jill Trewhella
- the School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia,; the Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Davide Comoletti
- From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and; Pediatrics, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey 08901,.
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28
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Shrivastava AN, Redeker V, Fritz N, Pieri L, Almeida LG, Spolidoro M, Liebmann T, Bousset L, Renner M, Léna C, Aperia A, Melki R, Triller A. Data in support of the identification of neuronal and astrocyte proteins interacting with extracellularly applied oligomeric and fibrillar α-synuclein assemblies by mass spectrometry. Data Brief 2016; 7:221-8. [PMID: 26958642 PMCID: PMC4773484 DOI: 10.1016/j.dib.2016.02.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 12/08/2015] [Accepted: 02/04/2016] [Indexed: 12/17/2022] Open
Abstract
α-Synuclein (α-syn) is the principal component of Lewy bodies, the pathophysiological hallmark of individuals affected by Parkinson disease (PD). This neuropathologic form of α-syn contributes to PD progression and propagation of α-syn assemblies between neurons. The data we present here support the proteomic analysis used to identify neuronal proteins that specifically interact with extracellularly applied oligomeric or fibrillar α-syn assemblies (conditions 1 and 2, respectively) (doi: 10.15252/embj.201591397[1]). α-syn assemblies and their cellular partner proteins were pulled down from neuronal cell lysed shortly after exposure to exogenous α-syn assemblies and the associated proteins were identified by mass spectrometry using a shotgun proteomic-based approach. We also performed experiments on pure cultures of astrocytes to identify astrocyte-specific proteins interacting with oligomeric or fibrillar α-syn (conditions 3 and 4, respectively). For each condition, proteins interacting selectively with α-syn assemblies were identified by comparison to proteins pulled-down from untreated cells used as controls. The mass spectrometry data, the database search and the peak lists have been deposited to the ProteomeXchange Consortium database via the PRIDE partner repository with the dataset identifiers PRIDE: PXD002256 to PRIDE: PXD002263 and doi: 10.6019/PXD002256 to 10.6019/PXD002263.
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Affiliation(s)
- Amulya Nidhi Shrivastava
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Virginie Redeker
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
- Corresponding author.
| | - Nicolas Fritz
- Department of Women and Children׳s Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Laura Pieri
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
| | - Leandro G. Almeida
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Maria Spolidoro
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Thomas Liebmann
- Department of Women and Children׳s Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Luc Bousset
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
| | - Marianne Renner
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Clément Léna
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Anita Aperia
- Department of Women and Children׳s Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Ronald Melki
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
| | - Antoine Triller
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
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29
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Abstract
UNLABELLED Synapses depend on trafficking of key membrane proteins by lateral diffusion from surface populations and by exocytosis from intracellular pools. The cell adhesion molecule neurexin (Nrxn) plays essential roles in synapses, but the dynamics and regulation of its trafficking are unknown. Here, we performed single-particle tracking and live imaging of transfected, epitope-tagged Nrxn variants in cultured rat and mouse wild-type or knock-out neurons. We observed that structurally larger αNrxn molecules are more mobile in the plasma membrane than smaller βNrxns because αNrxns displayed higher diffusion coefficients in extrasynaptic regions and excitatory or inhibitory terminals. We found that well characterized interactions with extracellular binding partners regulate the surface mobility of Nrxns. Binding to neurexophilin-1 (Nxph1) reduced the surface diffusion of αNrxns when both molecules were coexpressed. Conversely, impeding other interactions by insertion of splice sequence #4 or removal of extracellular Ca(2+) augmented the mobility of αNrxns and βNrxns. We also determined that fast axonal transport delivers Nrxns to the neuronal surface because Nrxns comigrate as cargo on synaptic vesicle protein transport vesicles (STVs). Unlike surface mobility, intracellular transport of βNrxn(+) STVs was faster than that of αNrxns, but both depended on the microtubule motor protein KIF1A and neuronal activity regulated the velocity. Large spontaneous fusion of Nrxn(+) STVs occurred simultaneously with synaptophysin on axonal membranes mostly outside of active presynaptic terminals. Surface Nrxns enriched at synaptic terminals where αNrxns and Nxph1/αNrxns recruited GABAAR subunits. Therefore, our results identify regulated dynamic trafficking as an important property of Nrxns that corroborates their function at synapses. SIGNIFICANCE STATEMENT Synapses mediate most functions in our brains and depend on the precise and timely delivery of key molecules throughout life. Neurexins (Nrxns) are essential synaptic cell adhesion molecules that are involved in synaptic transmission and differentiation of synaptic contacts. In addition, Nrxns have been linked to neuropsychiatric diseases such as autism. Because little is known about the dynamic aspects of trafficking of neurexins to synapses, we investigated this important question using single-molecule tracking and time-lapse imaging. We identify distinct differences between major Nrxn variants both in surface mobility and during intracellular transport. Because their dynamic behavior is highly regulated, for example, by different binding activities, these processes have immediate consequences for the function of Nrxns at synapses.
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30
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Schreiner D, Simicevic J, Ahrné E, Schmidt A, Scheiffele P. Quantitative isoform-profiling of highly diversified recognition molecules. eLife 2015; 4:e07794. [PMID: 25985086 PMCID: PMC4489214 DOI: 10.7554/elife.07794] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/14/2015] [Indexed: 12/28/2022] Open
Abstract
Complex biological systems rely on cell surface cues that govern cellular self-recognition and selective interactions with appropriate partners. Molecular diversification of cell surface recognition molecules through DNA recombination and complex alternative splicing has emerged as an important principle for encoding such interactions. However, the lack of tools to specifically detect and quantify receptor protein isoforms is a major impediment to functional studies. We here developed a workflow for targeted mass spectrometry by selected reaction monitoring that permits quantitative assessment of highly diversified protein families. We apply this workflow to dissecting the molecular diversity of the neuronal neurexin receptors and uncover an alternative splicing-dependent recognition code for synaptic ligands. DOI:http://dx.doi.org/10.7554/eLife.07794.001 To create a protein, a gene is first copied to form an RNA molecule that contains regions known as introns and exons. Splicing removes the introns and joins the exons together to form a molecule of ‘messenger RNA’, which is translated into a protein. Over the course of evolution, many groups—or families—of proteins have expanded and diversified their roles. One way in which this can occur is through a process known as alternative splicing, in which different exons can be included or excluded to generate the final messenger RNA. In this way, a single gene can produce a number of different proteins. These closely related proteins are known as isoforms. The brain contains billions of neurons that communicate with one another across connections known as synapses. A family of proteins called neurexins helps neurons to form these synapses. Humans have three neurexin genes, which undergo extensive alternative splicing to produce thousands of protein isoforms. However, it is not known whether all of these isoforms are produced in neurons, as existing experimental techniques were not sensitive enough to easily distinguish one isoform from another. A technique known as ‘selected reaction monitoring’ (or SRM for short) has recently emerged as a promising way to identify proteins. This allows proteins containing specific sequences to be separated out for analysis, in contrast to existing techniques that test randomly selected protein samples, which will result in most isoforms being missed. Schreiner, Simicevic et al. have now developed SRM further and show that this technique can detect the identity and amount of the neurexin isoforms present at synapses, including those that are only produced in very small quantities. Using SRM, Schreiner, Simicevic et al. demonstrate that neurexin isoforms differ in how they interact with synaptic receptors. Thus, alternative splicing of neurexins underlies a ‘recognition code’ at neuronal synapses. In the future, this newly developed SRM method could be used to investigate isoforms in other protein families and tissues, and so may prove valuable for understanding how a wide range of cellular recognition processes work. DOI:http://dx.doi.org/10.7554/eLife.07794.002
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Affiliation(s)
| | | | - Erik Ahrné
- Biozentrum, University of Basel, Basel, Switzerland
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31
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Targeted next-generation sequencing reveals novel EYS mutations in Chinese families with autosomal recessive retinitis pigmentosa. Sci Rep 2015; 5:8927. [PMID: 25753737 PMCID: PMC4354143 DOI: 10.1038/srep08927] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/10/2015] [Indexed: 11/11/2022] Open
Abstract
EYS mutations demonstrate great genotypic and phenotypic varieties, and are one of the major causes for patients with autosomal recessive retinitis pigmentosa (ARRP). Here, we aim to determine the genetic lesions with phenotypic correlations in two Chinese families with ARRP. Medical histories and ophthalmic documentations were obtained from all participants from the two pedigrees. Targeted next-generation sequencing (NGS) on 189 genes was performed to screen for RP causative mutations in the two families. Two biallelic mutations in EYS, p.[R164*];[C2139Y] and p.[W2640*];[F2954S], were identified in the two families, respectively. EYS p.R164* and p.F2954S are novel alleles associated with RP, while p.C2139Y and p.W2640* are known mutations. Crystal structure modeling on the protein eyes shut homolog encoded by the EYS gene revealed abnormal hydrogen bonds generated by p.C2139Y and p.F2954S, which would likely affect the solubility and cause significant structural changes of the two mutated proteins. In conclusion, our study expands the genotypic spectrums for EYS mutations, and may provide novel insights into the relevant pathogenesis for RP. We also demonstrate targeted NGS approach as a valuable tool for genetic diagnosis.
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32
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Abstract
The neurexin family of cell adhesion proteins consists of three members in
vertebrates and has homologs in several invertebrate species. In mammals, each
neurexin gene encodes an α-neurexin in which the extracellular portion is long,
and a β-neurexin in which the extracellular portion is short. As a result of
alternative splicing, both major isoforms can be transcribed in many variants,
contributing to distinct structural domains and variability. Neurexins act
predominantly at the presynaptic terminal in neurons and play essential roles in
neurotransmission and differentiation of synapses. Some of these functions require
the formation of trans-synaptic complexes with postsynaptic proteins such as
neuroligins, LRRTM proteins or cerebellin. In addition, rare mutations and
copy-number variations of human neurexin genes have been linked to autism and
schizophrenia, indicating that impairments of synaptic function sustained by
neurexins and their binding partners may be relevant to the pathomechanism of these
debilitating diseases.
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33
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Coles CH, Jones EY, Aricescu AR. Extracellular regulation of type IIa receptor protein tyrosine phosphatases: mechanistic insights from structural analyses. Semin Cell Dev Biol 2015; 37:98-107. [PMID: 25234613 PMCID: PMC4765084 DOI: 10.1016/j.semcdb.2014.09.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 09/02/2014] [Accepted: 09/05/2014] [Indexed: 01/06/2023]
Abstract
The receptor protein tyrosine phosphatases (RPTPs) exhibit a wide repertoire of cellular signalling functions. In particular, type IIa RPTP family members have recently been highlighted as hubs for extracellular interactions in neurons, regulating neuronal extension and guidance, as well as synaptic organisation. In this review, we will discuss the recent progress of structural biology investigations into the architecture of type IIa RPTP ectodomains and their interactions with extracellular ligands. Structural insights, in combination with biophysical and cellular studies, allow us to begin to piece together molecular mechanisms for the transduction and integration of type IIa RPTP signals and to propose hypotheses for future experimental validation.
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Affiliation(s)
- Charlotte H Coles
- Laboratory for Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
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Lu Z, Wang Y, Chen F, Tong H, Reddy MVVVS, Luo L, Seshadrinathan S, Zhang L, Holthauzen LMF, Craig AM, Ren G, Rudenko G. Calsyntenin-3 molecular architecture and interaction with neurexin 1α. J Biol Chem 2014; 289:34530-42. [PMID: 25352602 DOI: 10.1074/jbc.m114.606806] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Calsyntenin 3 (Cstn3 or Clstn3), a recently identified synaptic organizer, promotes the development of synapses. Cstn3 localizes to the postsynaptic membrane and triggers presynaptic differentiation. Calsyntenin members play an evolutionarily conserved role in memory and learning. Cstn3 was recently shown in cell-based assays to interact with neurexin 1α (n1α), a synaptic organizer that is implicated in neuropsychiatric disease. Interaction would permit Cstn3 and n1α to form a trans-synaptic complex and promote synaptic differentiation. However, it is contentious whether Cstn3 binds n1α directly. To understand the structure and function of Cstn3, we determined its architecture by electron microscopy and delineated the interaction between Cstn3 and n1α biochemically and biophysically. We show that Cstn3 ectodomains form monomers as well as tetramers that are stabilized by disulfide bonds and Ca(2+), and both are probably flexible in solution. We show further that the extracellular domains of Cstn3 and n1α interact directly and that both Cstn3 monomers and tetramers bind n1α with nanomolar affinity. The interaction is promoted by Ca(2+) and requires minimally the LNS domain of Cstn3. Furthermore, Cstn3 uses a fundamentally different mechanism to bind n1α compared with other neurexin partners, such as the synaptic organizer neuroligin 2, because Cstn3 does not strictly require the sixth LNS domain of n1α. Our structural data suggest how Cstn3 as a synaptic organizer on the postsynaptic membrane, particularly in tetrameric form, may assemble radially symmetric trans-synaptic bridges with the presynaptic synaptic organizer n1α to recruit and spatially organize proteins into networks essential for synaptic function.
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Affiliation(s)
- Zhuoyang Lu
- the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, the School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yun Wang
- the University of Michigan, Ann Arbor, Michigan 48109
| | - Fang Chen
- the University of Michigan, Ann Arbor, Michigan 48109
| | - Huimin Tong
- the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | | | - Lin Luo
- the Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada, and
| | | | - Lei Zhang
- the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Luis Marcelo F Holthauzen
- the Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston Texas 77555
| | - Ann Marie Craig
- the Department of Psychiatry, University of British Columbia, Vancouver V6T 2A1, Canada, and
| | - Gang Ren
- the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720,
| | - Gabby Rudenko
- From the Department of Pharmacology and Toxicology and the Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston Texas 77555,
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Targeted combinatorial alternative splicing generates brain region-specific repertoires of neurexins. Neuron 2014; 84:386-98. [PMID: 25284007 DOI: 10.1016/j.neuron.2014.09.011] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2014] [Indexed: 11/20/2022]
Abstract
Molecular diversity of surface receptors has been hypothesized to provide a mechanism for selective synaptic connectivity. Neurexins are highly diversified receptors that drive the morphological and functional differentiation of synapses. Using a single cDNA sequencing approach, we detected 1,364 unique neurexin-α and 37 neurexin-β mRNAs produced by alternative splicing of neurexin pre-mRNAs. This molecular diversity results from near-exhaustive combinatorial use of alternative splice insertions in Nrxn1α and Nrxn2α. By contrast, Nrxn3α exhibits several highly stereotyped exon selections that incorporate novel elements for posttranscriptional regulation of a subset of transcripts. Complexity of Nrxn1α repertoires correlates with the cellular complexity of neuronal tissues, and a specific subset of isoforms is enriched in a purified cell type. Our analysis defines the molecular diversity of a critical synaptic receptor and provides evidence that neurexin diversity is linked to cellular diversity in the nervous system.
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Tong XH, Wu GZ. Central glucose sensing. NUTR CLIN METAB 2014. [DOI: 10.1016/j.nupar.2014.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Reissner C, Stahn J, Breuer D, Klose M, Pohlentz G, Mormann M, Missler M. Dystroglycan binding to α-neurexin competes with neurexophilin-1 and neuroligin in the brain. J Biol Chem 2014; 289:27585-603. [PMID: 25157101 PMCID: PMC4183798 DOI: 10.1074/jbc.m114.595413] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
α-Neurexins (α-Nrxn) are mostly presynaptic cell surface molecules essential for neurotransmission that are linked to neuro-developmental disorders as autism or schizophrenia. Several interaction partners of α-Nrxn are identified that depend on alternative splicing, including neuroligins (Nlgn) and dystroglycan (αDAG). The trans-synaptic complex with Nlgn1 was extensively characterized and shown to partially mediate α-Nrxn function. However, the interactions of α-Nrxn with αDAG, neurexophilins (Nxph1) and Nlgn2, ligands that occur specifically at inhibitory synapses, are incompletely understood. Using site-directed mutagenesis, we demonstrate the exact binding epitopes of αDAG and Nxph1 on Nrxn1α and show that their binding is mutually exclusive. Identification of an unusual cysteine bridge pattern and complex type glycans in Nxph1 ensure binding to the second laminin/neurexin/sex hormone binding (LNS2) domain of Nrxn1α, but this association does not interfere with Nlgn binding at LNS6. αDAG, in contrast, interacts with both LNS2 and LNS6 domains without inserts in splice sites SS#2 or SS#4 mostly via LARGE (like-acetylglucosaminyltransferase)-dependent glycans attached to the mucin region. Unexpectedly, binding of αDAG at LNS2 prevents interaction of Nlgn at LNS6 with or without splice insert in SS#4, presumably by sterically hindering each other in the u-form conformation of α-Nrxn. Thus, expression of αDAG and Nxph1 together with alternative splicing in Nrxn1α may prevent or facilitate formation of distinct trans-synaptic Nrxn·Nlgn complexes, revealing an unanticipated way to contribute to the identity of synaptic subpopulations.
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Affiliation(s)
- Carsten Reissner
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Johanna Stahn
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Dorothee Breuer
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Martin Klose
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Gottfried Pohlentz
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University, Robert-Koch Strasse 31, 48149 Münster, Germany, and
| | - Michael Mormann
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University, Robert-Koch Strasse 31, 48149 Münster, Germany, and
| | - Markus Missler
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany, Cluster of Excellence EXC 1003, Cells in Motion, 48149 Münster, Germany
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Yangngam S, Plong-On O, Sripo T, Roongpraiwan R, Hansakunachai T, Wirojanan J, Sombuntham T, Ruangdaraganon N, Limprasert P. Mutation screening of the neurexin 1 gene in thai patients with intellectual disability and autism spectrum disorder. Genet Test Mol Biomarkers 2014; 18:510-5. [PMID: 24832020 DOI: 10.1089/gtmb.2014.0003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIM Neurexin 1 has two major protein isoforms using alternative promoters, coding for the alpha-neurexin 1 (α-NRXN1) and beta-neurexin 1 (β-NRXN1) genes. This study is to explore the possibility that variants of the NRXN1 gene predispose to intellectual disability (ID) and autism spectrum disorder (ASD). METHODS The coding regions in 24 exons and exon-intron boundaries of the NRXN1 gene were investigated in 115 Thai patients with ID and ASD by direct DNA sequencing. RESULTS Nine novel variants of the NRXN1 gene were identified. Four novel variants were found in the β-NRXN1 gene, one variant of six GGC repeats in exon 1, and three variants at the 5'UTR. Five novel variants were identified in the α-NRXN1 gene, four intronic variants and one missense variant in exon 14 (c.2713T>A or p.F905I). CONCLUSION Mutation screening of the NRXN1gene in patients with ID and ASD may be useful to identify potential variants predisposing to ID and ASD. However, further studies utilizing protein functional analysis of the novel variants are required for a more definite conclusion.
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Affiliation(s)
- Supaporn Yangngam
- 1 Graduate Program in Biomedical Sciences, Faculty of Medicine, Prince of Songkla University , Hat Yai, Songkhla, Thailand
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Cartography of neurexin alternative splicing mapped by single-molecule long-read mRNA sequencing. Proc Natl Acad Sci U S A 2014; 111:E1291-9. [PMID: 24639501 DOI: 10.1073/pnas.1403244111] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurexins are evolutionarily conserved presynaptic cell-adhesion molecules that are essential for normal synapse formation and synaptic transmission. Indirect evidence has indicated that extensive alternative splicing of neurexin mRNAs may produce hundreds if not thousands of neurexin isoforms, but no direct evidence for such diversity has been available. Here we use unbiased long-read sequencing of full-length neurexin (Nrxn)1α, Nrxn1β, Nrxn2β, Nrxn3α, and Nrxn3β mRNAs to systematically assess how many sites of alternative splicing are used in neurexins with a significant frequency, and whether alternative splicing events at these sites are independent of each other. In sequencing more than 25,000 full-length mRNAs, we identified a novel, abundantly used alternatively spliced exon of Nrxn1α and Nrxn3α (referred to as alternatively spliced sequence 6) that encodes a 9-residue insertion in the flexible hinge region between the fifth LNS (laminin-α, neurexin, sex hormone-binding globulin) domain and the third EGF-like sequence. In addition, we observed several larger-scale events of alternative splicing that deleted multiple domains and were much less frequent than the canonical six sites of alternative splicing in neurexins. All of the six canonical events of alternative splicing appear to be independent of each other, suggesting that neurexins may exhibit an even larger isoform diversity than previously envisioned and comprise thousands of variants. Our data are consistent with the notion that α-neurexins represent extracellular protein-interaction scaffolds in which different LNS and EGF domains mediate distinct interactions that affect diverse functions and are independently regulated by independent events of alternative splicing.
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40
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The neuroligins and their ligands: from structure to function at the synapse. J Mol Neurosci 2014; 53:387-96. [PMID: 24497299 DOI: 10.1007/s12031-014-0234-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/10/2014] [Indexed: 10/25/2022]
Abstract
The neuroligins are cell adhesion proteins whose extracellular domain belongs to the α/β-hydrolase fold family of proteins, mainly containing enzymes and exemplified by acetylcholinesterase. The ectodomain of postsynaptic neuroligins interacts through a calcium ion with the ectodomain of presynaptic neurexins to form flexible trans-synaptic associations characterized by selectivity for neuroligin or neurexin subtypes. This heterophilic interaction, essential for synaptic differentiation, maturation, and maintenance, is regulated by gene selection, alternative mRNA splicing, and posttranslational modifications. Mutations leading to deficiencies in the expression, folding, maturation, and binding properties of either partner are associated with autism spectrum disorders. The currently available structural and functional data illustrate how these two families of cell adhesion molecules bridge the synaptic cleft to participate in synapse plasticity and support its dynamic nature. Neuroligin partners distinct from the neurexins, and which may undergo either trans or cis interaction, have also been described, and tridimensional structures of some of them are available. Our study emphasizes the partnership versatility of the neuroligin ectodomain associated with molecular flexibility and alternative binding sites, proposes homology models of the structurally non-characterized neuroligin partners, and exemplifies the large structural variability at the surface of the α/β-hydrolase fold subunit. This study also provides new insights into possible surface binding sites associated with non-catalytic properties of the acetylcholinesterase subunit.
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Gokce O, Südhof TC. Membrane-tethered monomeric neurexin LNS-domain triggers synapse formation. J Neurosci 2013; 33:14617-28. [PMID: 24005312 PMCID: PMC3761060 DOI: 10.1523/jneurosci.1232-13.2013] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 07/10/2013] [Accepted: 08/03/2013] [Indexed: 12/20/2022] Open
Abstract
Neurexins are presynaptic cell-adhesion molecules that bind to postsynaptic cell-adhesion molecules such as neuroligins and leucine-rich repeat transmembrane proteins (LRRTMs). When neuroligins or LRRTMs are expressed in a nonneuronal cell, cocultured neurons avidly form heterologous synapses onto that cell. Here we show that knockdown of all neurexins in cultured hippocampal mouse neurons did not impair synapse formation between neurons, but blocked heterologous synapse formation induced by neuroligin-1 or LRRTM2. Rescue experiments demonstrated that all neurexins tested restored heterologous synapse formation in neurexin-deficient neurons. Neurexin-deficient neurons exhibited a decrease in the levels of the PDZ-domain protein CASK (a calcium/calmodulin-activated serine/threonine kinase), which binds to neurexins, and mutation of the PDZ-domain binding sequence of neurexin-3β blocked its transport to the neuronal surface and impaired heterologous synapse formation. However, replacement of the C-terminal neurexin sequence with an unrelated PDZ-domain binding sequence that does not bind to CASK fully restored surface transport and heterologous synapse formation in neurexin-deficient neurons, suggesting that no particular PDZ-domain protein is essential for neurexin surface transport or heterologous synapse formation. Further mutagenesis revealed, moreover, that the entire neurexin cytoplasmic tail was dispensable for heterologous synapse formation in neurexin-deficient neurons, as long as the neurexin protein was transported to the neuronal cell surface. Furthermore, the single LNS-domain (for laminin/neurexin/sex hormone-binding globulin-domain) of neurexin-1β or neurexin-3β, when tethered to the presynaptic plasma membrane by a glycosylinositolphosphate anchor, was sufficient for rescuing heterologous synapse formation in neurexin-deficient neurons. Our data suggest that neurexins mediate heterologous synapse formation via an extracellular interaction with presynaptic and postsynaptic ligands without the need for signal transduction by the neurexin cytoplasmic tail.
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Affiliation(s)
- Ozgun Gokce
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, Stanford, California 94305-5453
| | - Thomas C. Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, Stanford, California 94305-5453
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Aricescu AR, Owens RJ. Expression of recombinant glycoproteins in mammalian cells: towards an integrative approach to structural biology. Curr Opin Struct Biol 2013; 23:345-56. [PMID: 23623336 DOI: 10.1016/j.sbi.2013.04.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 03/30/2013] [Accepted: 04/02/2013] [Indexed: 01/26/2023]
Abstract
Mammalian cells are rapidly becoming the system of choice for the production of recombinant glycoproteins for structural biology applications. Their use has enabled the structural investigation of a whole new set of targets including large, multi-domain and highly glycosylated eukaryotic cell surface receptors and their supra-molecular assemblies. We summarize the technical advances that have been made in mammalian expression technology and highlight some of the structural insights that have been obtained using these methods. Looking forward, it is clear that mammalian cell expression will provide exciting and unique opportunities for an integrative approach to the structural study of proteins, especially of human origin and medically relevant, by bridging the gap between the purified state and the cellular context.
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Affiliation(s)
- A Radu Aricescu
- Division of Structural Biology, University of Oxford, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
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Bang ML, Owczarek S. A Matter of Balance: Role of Neurexin and Neuroligin at the Synapse. Neurochem Res 2013; 38:1174-89. [DOI: 10.1007/s11064-013-1029-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 02/01/2013] [Accepted: 03/26/2013] [Indexed: 11/29/2022]
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Cholinesterase confabs and cousins: approaching forty years. Chem Biol Interact 2013; 203:10-3. [PMID: 23085121 DOI: 10.1016/j.cbi.2012.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 10/04/2012] [Accepted: 10/09/2012] [Indexed: 11/23/2022]
Abstract
In the past four decades of cholinesterase (ChE) research, we have seen substantive evolution of the field from one centered around substrate and inhibitor kinetic profiles and compound characterizations to the analysis of ChE structure, first through the gene families and then by X-ray crystallographic determinations of the free enzymes and their complexes and conjugates. Indeed, these endeavors have been facilitated by recombinant DNA technologies, structure determinations and parallel studies in related proteins in the α/β-hydrolase fold family. This approach has not only contributed to a fundamental understanding of structure and function of a large family of hydrolase-like proteins possessing functions other than catalysis, but also has been used to develop new practical strategies for scavenging and antidotal activity in cases of organophosphate insecticide or nerve agent exposure.
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Graziano S, Marchiò S, Bussolino F, Arese M. A peptide from the extracellular region of the synaptic protein α Neurexin stimulates angiogenesis and the vascular specific tyrosine kinase Tie2. Biochem Biophys Res Commun 2013; 432:574-9. [PMID: 23485462 DOI: 10.1016/j.bbrc.2013.02.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 02/14/2013] [Indexed: 11/27/2022]
Abstract
Neurexin (NRXN) and Neuroligin (NLGN) are trans-synaptic proteins involved in vascular biology. NRXN is encoded in long (α) and short (β) isoforms. We have shown that βNRXN modulates blood vessel development in synergy with VEGFA and associates with NLGN. On the other hand αNRXN is also expressed in blood vessels but does not interact with NLGN or act in synergy with VEGFA, thus demonstrating a differential role. To find clues into the vascular functions of αNRXN, we chose a 7 aa motif that is part of its extracellular region and was formerly selected through a proteomic search for interactors of the vascular receptor Tie2. Next we (a) synthetized and modeled such peptide in order to determine its biological activity towards Tie2 in in vitro and in vivo angiogenesis assays and (b) evaluated if αNRXN and Tie2 physically associate in situ during vascular development. We used biochemical and cellular assays to prove that the synthetic αNRXN peptide (a) modulates the angiogenic phenotype of cultured endothelial cells and angiogenesis in vivo and (b) efficiently stimulates Tie2 phosphorylation and downstream mediators in endothelial cells. Moreover, we show that αNRXN and Tie2 can be reciprocally immunoprecipitated from chicken blood vessels at late stages of vascular development. These data have a double significance, i.e. provide a novel tool to modulate Tie2 and further suggest the involvement of the NRXN family of synaptic protein in the vascular system through their interaction with a fundamental vascular player.
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Affiliation(s)
- Stefania Graziano
- Department of Oncology, University of Torino Medical School, and Laboratory of Neurovascular Biology, Institute for Cancer Research @ Candiolo, Candiolo (TO), Italy
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Abstract
The neurexin genes (NRXN1, NRXN2, and NRXN3) encode polymorphic presynaptic proteins that are implicated in synaptic plasticity and memory processing. In rat brain neurons grown in culture, depolarization induces reversible, calcium-dependent, repression of NRXN2α exon 11 (E11) splicing. Using Neuro2a cells as a model, we explored E11 cis elements and trans-acting factors involved in alternative splicing of NRXN2α E11 pre-mRNA under basal and depolarization conditions. E11 mutation studies revealed two motifs, CTGCCTG (enhancer) and GCACCCA (suppressor) regulating NRXN2α E11 alternative splicing. Subsequent E11 RNA affinity pull-down experiments demonstrated heterogeneous nuclear ribonucleoprotein (hnRNP) K and hnRNP L binding to this exon. Under depolarization, the amount of E11-bound hnRNP L (but not of hnRNP K) increased, in parallel to NRXN2α E11 splicing repression. Depletion of hnRNP K or hnRNP L in the Neuro2a cells by specific siRNAs enhanced NRXN2α E11 splicing and ablated the depolarization-induced repression of this exon. In addition, depolarization suppressed whereas hnRNP K depletion enhanced NRXN2α expression. These results indicate a role for hnRNP K in regulation of NRXN2α expression and of hnRNP L in the activity-dependent alternative splicing of neurexins which may potentially govern trans-synaptic signaling required for memory processing.
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De Jaco A, Dubi N, Camp S, Taylor P. Congenital hypothyroidism mutations affect common folding and trafficking in the α/β-hydrolase fold proteins. FEBS J 2012; 279:4293-305. [PMID: 23035660 DOI: 10.1111/febs.12019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/27/2012] [Accepted: 09/28/2012] [Indexed: 12/19/2022]
Abstract
The α/β-hydrolase fold superfamily of proteins is composed of structurally related members that, despite great diversity in their catalytic, recognition, adhesion and chaperone functions, share a common fold governed by homologous residues and conserved disulfide bridges. Non-synonymous single nucleotide polymorphisms within the α/β-hydrolase fold domain in various family members have been found for congenital endocrine, metabolic and nervous system disorders. By examining the amino acid sequence from the various proteins, mutations were found to be prevalent in conserved residues within the α/β-hydrolase fold of the homologous proteins. This is the case for the thyroglobulin mutations linked to congenital hypothyroidism. To address whether correct folding of the common domain is required for protein export, we inserted the thyroglobulin mutations at homologous positions in two correlated but simpler α/β-hydrolase fold proteins known to be exported to the cell surface: neuroligin3 and acetylcholinesterase. Here we show that these mutations in the cholinesterase homologous region alter the folding properties of the α/β-hydrolase fold domain, which are reflected in defects in protein trafficking, folding and function, and ultimately result in retention of the partially processed proteins in the endoplasmic reticulum. Accordingly, mutations at conserved residues may be transferred amongst homologous proteins to produce common processing defects despite disparate functions, protein complexity and tissue-specific expression of the homologous proteins. More importantly, a similar assembly of the α/β-hydrolase fold domain tertiary structure among homologous members of the superfamily is required for correct trafficking of the proteins to their final destination.
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Affiliation(s)
- Antonella De Jaco
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA.
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Falivelli G, De Jaco A, Favaloro FL, Kim H, Wilson J, Dubi N, Ellisman MH, Abrahams BS, Taylor P, Comoletti D. Inherited genetic variants in autism-related CNTNAP2 show perturbed trafficking and ATF6 activation. Hum Mol Genet 2012; 21:4761-73. [PMID: 22872700 DOI: 10.1093/hmg/dds320] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although genetic variations in several genes encoding for synaptic adhesion proteins have been found to be associated with autism spectrum disorders, one of the most consistently replicated genes has been CNTNAP2, encoding for contactin-associated protein-like 2 (CASPR2), a multidomain transmembrane protein of the neurexin superfamily. Using immunofluorescence confocal microscopy and complementary biochemical techniques, we compared wild-type CASPR2 to 12 point mutations identified in individuals with autism. In contrast to the wild-type protein, localized to the cell surface, some of the mutants show altered cellular disposition. In particular, CASPR2-D1129H is largely retained in the endoplasmic reticulum (ER) in HEK-293 cells and in hippocampal neurons. BiP/Grp78, Calnexin and ERp57, key ER chaperones, appear to be responsible for retention of this mutant and activation of one signaling pathway of the unfolded protein response (UPR). The presence of this mutation also lowers expression and activates proteosomal degradation. A frame-shift mutation that causes a form of syndromic epilepsy (CASPR2-1253*), results in a secreted protein with seemingly normal folding and oligomerization. Taken together, these data indicate that CASPR2-D1129H has severe trafficking abnormalities and CASPR2-1253* is a secreted soluble protein, suggesting that the structural or signaling functions of the membrane tethered form are lost. Our data support a complex genetic architecture in which multiple distinct risk factors interact with others to shape autism risk and presentation.
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Affiliation(s)
- Giulia Falivelli
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA
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Tanaka H, Miyazaki N, Matoba K, Nogi T, Iwasaki K, Takagi J. Higher-Order Architecture of Cell Adhesion Mediated by Polymorphic Synaptic Adhesion Molecules Neurexin and Neuroligin. Cell Rep 2012; 2:101-10. [DOI: 10.1016/j.celrep.2012.06.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 05/07/2012] [Accepted: 06/11/2012] [Indexed: 11/24/2022] Open
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Suckow AT, Zhang C, Egodage S, Comoletti D, Taylor P, Miller MT, Sweet IR, Chessler SD. Transcellular neuroligin-2 interactions enhance insulin secretion and are integral to pancreatic β cell function. J Biol Chem 2012; 287:19816-26. [PMID: 22528485 DOI: 10.1074/jbc.m111.280537] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Normal glucose-stimulated insulin secretion is dependent on interactions between neighboring β cells. Elucidation of the reasons why this cell-to-cell contact is essential will probably yield critical insights into β cell maturation and function. In the central nervous system, transcellular protein interactions (i.e. interactions between proteins on the surfaces of different cells) involving neuroligins are key mediators of synaptic functional development. We previously demonstrated that β cells express neuroligin-2 and that insulin secretion is affected by changes in neuroligin-2 expression. Here we show that the effect of neuroligin-2 on insulin secretion is mediated by transcellular interactions. Neuroligin-2 binds with nanomolar affinity to a partner on the β cell surface and contributes to the increased insulin secretion brought about by β cell-to-β cell contact. It does so in a manner seemingly independent of interactions with neurexin, a known binding partner. As in the synapse, transcellular neuroligin-2 interactions enhance the functioning of the submembrane exocytic machinery. Also, as in the synapse, neuroligin-2 clustering is important. Neuroligin-2 in soluble form, rather than presented on a cell surface, decreases insulin secretion by rat islets and MIN-6 cells, most likely by interfering with endogenous neuroligin interactions. Prolonged contact with neuroligin-2-expressing cells increases INS-1 β cell proliferation and insulin content. These results extend the known parallels between the synaptic and β cell secretory machineries to extracellular interactions. Neuroligin-2 interactions are one of the few transcellular protein interactions thus far identified that directly enhance insulin secretion. Together, these results indicate a significant role for transcellular neuroligin-2 interactions in the establishment of β cell function.
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Affiliation(s)
- Arthur T Suckow
- Department of Medicine and Pediatric Diabetes Research Center, UCSD School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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