1
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Cortés E, Pak JS, Özkan E. Structure and evolution of neuronal wiring receptors and ligands. Dev Dyn 2023; 252:27-60. [PMID: 35727136 PMCID: PMC10084454 DOI: 10.1002/dvdy.512] [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: 04/18/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 01/04/2023] Open
Abstract
One of the fundamental properties of a neuronal circuit is the map of its connections. The cellular and developmental processes that allow for the growth of axons and dendrites, selection of synaptic targets, and formation of functional synapses use neuronal surface receptors and their interactions with other surface receptors, secreted ligands, and matrix molecules. Spatiotemporal regulation of the expression of these receptors and cues allows for specificity in the developmental pathways that wire stereotyped circuits. The families of molecules controlling axon guidance and synapse formation are generally conserved across animals, with some important exceptions, which have consequences for neuronal connectivity. Here, we summarize the distribution of such molecules across multiple taxa, with a focus on model organisms, evolutionary processes that led to the multitude of such molecules, and functional consequences for the diversification or loss of these receptors.
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Affiliation(s)
- Elena Cortés
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.,The Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
| | - Joseph S Pak
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.,The Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.,The Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
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2
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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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3
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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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4
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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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5
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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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6
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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: 471] [Impact Index Per Article: 67.3] [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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7
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Shao Q, Lindstrom K, Shi R, Kelly J, Schroeder A, Juusola J, Levine KL, Esseltine JL, Penuela S, Jackson MF, Laird DW. A Germline Variant in the PANX1 Gene Has Reduced Channel Function and Is Associated with Multisystem Dysfunction. J Biol Chem 2016; 291:12432-12443. [PMID: 27129271 DOI: 10.1074/jbc.m116.717934] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 12/20/2022] Open
Abstract
Pannexin1 (PANX1) is probably best understood as an ATP release channel involved in paracrine signaling. Given its ubiquitous expression, PANX1 pathogenic variants would be expected to lead to disorders involving multiple organ systems. Using whole exome sequencing, we discovered the first patient with a homozygous PANX1 variant (c.650G→A) resulting in an arginine to histidine substitution at position 217 (p.Arg217His). The 17-year-old female has intellectual disability, sensorineural hearing loss requiring bilateral cochlear implants, skeletal defects, including kyphoscoliosis, and primary ovarian failure. Her consanguineous parents are each heterozygous for this variant but are not affected by the multiorgan syndromes noted in the proband. Expression of the p.Arg217His mutant in HeLa, N2A, HEK293T, and Ad293 cells revealed normal PANX1 glycosylation and cell surface trafficking. Dye uptake, ATP release, and electrophysiological measurements revealed p.Arg217His to be a loss-of-function variant. Co-expression of the mutant with wild-type PANX1 suggested the mutant was not dominant-negative to PANX1 channel function. Collectively, we demonstrate a PANX1 missense change associated with human disease in the first report of a "PANX1-related disorder."
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Affiliation(s)
- Qing Shao
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Kristin Lindstrom
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, Arizona 85016
| | - Ruoyang Shi
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0Z3, Canada,; Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba R3E 0Z3, Canada
| | - John Kelly
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Audrey Schroeder
- Division of Genetics, University of Rochester Medical Center, Rochester, New York 14642
| | | | | | - Jessica L Esseltine
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Michael F Jackson
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0Z3, Canada,; Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba R3E 0Z3, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada.
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8
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Lai JKY, Doering LC, Foster JA. Developmental expression of the neuroligins and neurexins in fragile X mice. J Comp Neurol 2015; 524:807-28. [PMID: 26235839 DOI: 10.1002/cne.23868] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 07/20/2015] [Accepted: 07/21/2015] [Indexed: 11/08/2022]
Abstract
Neuroligins and neurexins are transsynaptic proteins involved in the maturation of glutamatergic and GABAergic synapses. Research has identified synaptic proteins and function as primary contributors to the development of fragile X syndrome. Fragile X mental retardation protein (FMRP), the protein that is lacking in fragile X syndrome, binds neuroligin-1 and -3 mRNA. Using in situ hybridization, we examined temporal and spatial expression patterns of neuroligin (NLGN) and neurexin (NRXN) mRNAs in the somatosensory (S1) cortex and hippocampus in wild-type (WT) and fragile X knockout (FMR1-KO) mice during the first 5 weeks of postnatal life. Genotype-based differences in expression included increased NLGN1 mRNA in CA1 and S1 cortex, decreased NLGN2 mRNA in CA1 and dentate gyrus (DG) regions of the hippocampus, and increased NRXN3 mRNA in CA1, DG, and S1 cortex between female WT and FMR1-KO mice. In male mice, decreased expression of NRXN3 mRNA was observed in CA1 and DG regions of FMR1-KO mice. Sex differences in hippocampal expression of NLGN2, NRXN1, NRXN2, and NRXN3 mRNAs and in S1 cortex expression of NRXN3 mRNAs were observed WT mice, whereas sex differences in NLGN3, NRXN1, NRXN2, and NRXN3 mRNA expression in the hippocampus and in NLGN1, NRXN2 and NRXN3 mRNA expression in S1 cortex were detected in FMR1-KO mice. These results provide a neuroanatomical map of NLGN and NRXN expression patterns over postnatal development in WT and FMR1-KO mice. The differences in developmental trajectory of these synaptic proteins could contribute to long-term differences in CNS wiring and synaptic function.
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Affiliation(s)
- Jonathan K Y Lai
- Department of Psychiatry and Behavioural Neuroscience, McMaster University, Hamilton, Ontario, L8N 4L8, Canada.,Brain-Body Institute, St. Joseph's Healthcare, Hamilton, Ontario, L8N 4A6, Canada
| | - Laurie C Doering
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, L8N 4L8, Canada
| | - Jane A Foster
- Department of Psychiatry and Behavioural Neuroscience, McMaster University, Hamilton, Ontario, L8N 4L8, Canada.,Brain-Body Institute, St. Joseph's Healthcare, Hamilton, Ontario, L8N 4A6, Canada
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9
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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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10
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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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11
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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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12
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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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13
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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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14
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The role of neurexins and neuroligins in the formation, maturation, and function of vertebrate synapses. Curr Opin Neurobiol 2012; 22:412-22. [PMID: 22424845 DOI: 10.1016/j.conb.2012.02.012] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 02/23/2012] [Indexed: 11/20/2022]
Abstract
Neurexins (NXs) and neuroligins (NLs) are transsynaptically interacting cell adhesion proteins that play a key role in the formation, maturation, activity-dependent validation, and maintenance of synapses. As complex alternative splicing processes in nerve cells generate a large number of NX and NLs variants, it has been proposed that a combinatorial interaction code generated by these variants may determine synapse identity and network connectivity during brain development. The functional importance of NXs and NLs is exemplified by the fact that mutations in NX and NL genes are associated with several neuropsychiatric disorders, most notably with autism. Accordingly, major research efforts have focused on the molecular mechanisms by which NXs and NLs operate at synapses. In this review, we summarize recent progress in this field and discuss emerging topics, such as the role of alternative interaction partners of NXs and NLs in synapse formation and function, and their relevance for synaptic plasticity in the mature brain. The novel findings highlight the fundamental importance of NX-NL interactions in a wide range of synaptic functions.
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15
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Mikulska K, Strzelecki J, Balter A, Nowak W. Nanomechanical unfolding of α-neurexin: A major component of the synaptic junction. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2011.11.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Knight D, Xie W, Boulianne GL. Neurexins and neuroligins: recent insights from invertebrates. Mol Neurobiol 2011; 44:426-40. [PMID: 22037798 PMCID: PMC3229692 DOI: 10.1007/s12035-011-8213-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 10/17/2011] [Indexed: 11/28/2022]
Abstract
During brain development, each neuron must find and synapse with the correct pre- and postsynaptic partners. The complexity of these connections and the relatively large distances some neurons must send their axons to find the correct partners makes studying brain development one of the most challenging, and yet fascinating disciplines in biology. Furthermore, once the initial connections have been made, the neurons constantly remodel their dendritic and axonal arbours in response to changing demands. Neurexin and neuroligin are two cell adhesion molecules identified as important regulators of this process. The importance of these genes in the development and modulation of synaptic connectivity is emphasised by the observation that mutations in these genes in humans have been associated with cognitive disorders such as Autism spectrum disorders, Tourette syndrome and Schizophrenia. The present review will discuss recent advances in our understanding of the role of these genes in synaptic development and modulation, and in particular, we will focus on recent work in invertebrate models, and how these results relate to studies in mammals.
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Affiliation(s)
- David Knight
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
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Abstract
Neurexins are presynaptic transmembrane proteins that play an essential role in synapse function. The crystal structures of α-neurexin extracellular domains (Chen et al., 2011; Miller et al., 2011) provide important insights into their conformational freedom and their putative spatial arrangement with binding partners in the synaptic cleft.
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Affiliation(s)
- Carsten Reissner
- Department of Anatomy and Molecular Neurobiology, Westfälische Wilhems-University, Münster, Germany
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