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Shan D, Song Y, Zhang Y, Ho CW, Xia W, Li Z, Ge F, Ou Q, Dai Z, Dai Z. Neurexin dysfunction in neurodevelopmental and neuropsychiatric disorders: a PRIMSA-based systematic review through iPSC and animal models. Front Behav Neurosci 2024; 18:1297374. [PMID: 38380150 PMCID: PMC10876810 DOI: 10.3389/fnbeh.2024.1297374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/17/2024] [Indexed: 02/22/2024] Open
Abstract
Background Neurexins, essential synaptic proteins, are linked to neurodevelopmental and neuropsychiatric disorders like autism spectrum disorder (ASD) and schizophrenia. Objective Through this systematic review, we aimed to shed light on the relationship between neurexin dysfunction and its implications in neurodevelopmental and neuropsychiatric manifestations. Both animal and human-induced pluripotent stem cell (hiPSC) models served as our primary investigative platforms. Methods Utilizing the PRISMA 2020 guidelines, our search strategy involved scouring articles from the PubMed and Google Scholar databases covering a span of two decades (2003-2023). Of the initial collection, 27 rigorously evaluated studies formed the essence of our review. Results Our review suggested the significant ties between neurexin anomalies and neurodevelopmental and neuropsychiatric outcomes, most notably ASD. Rodent-based investigations delineated pronounced ASD-associated behaviors, and hiPSC models derived from ASD-diagnosed patients revealed the disruptions in calcium dynamics and synaptic activities. Additionally, our review underlined the integral role of specific neurexin variants, primarily NRXN1, in the pathology of schizophrenia. It was also evident from our observation that neurexin malfunctions were implicated in a broader array of these disorders, including ADHD, intellectual challenges, and seizure disorders. Conclusion This review accentuates the cardinal role neurexins play in the pathological process of neurodevelopmental and neuropsychiatric disorders. The findings underscore a critical need for standardized methodologies in developing animal and hiPSC models for future studies, aiming to minimize heterogeneity. Moreover, we highlight the need to expand research into less studied neurexin variants (i.e., NRXN2 and NRXN3), broadening the scope of our understanding in this field. Our observation also projects hiPSC models as potent tools for bridging research gaps, promoting translational research, and fostering the development of patient-specific therapeutic interventions.
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Affiliation(s)
- Dan Shan
- Department of Biobehavioral Sciences, Columbia University, New York, NY, United States
- Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - Yuming Song
- School of Medical Imaging, Hebei Medical University, Shijiazhuang, China
| | - Yanyi Zhang
- School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Cheong Wong Ho
- School of Medicine, University of Galway, Galway, Ireland
| | - Wenxin Xia
- School of Medicine, University of Galway, Galway, Ireland
| | - Zhi Li
- College of Health, Medicine and Wellbeing, University of Newcastle, Newcastle, NSW, Australia
| | - Fenfen Ge
- Faculty of Medicine, University of Iceland, Reykjavík, Iceland
| | - Qifeng Ou
- School of Medicine, University of Galway, Galway, Ireland
| | - Zijie Dai
- Division of Biosciences, Faculty of Life Sciences, University College London, London, United Kingdom
| | - Zhihao Dai
- School of Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
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Ducrot C, de Carvalho G, Delignat-Lavaud B, Delmas CVL, Halder P, Giguère N, Pacelli C, Mukherjee S, Bourque MJ, Parent M, Chen LY, Trudeau LE. Conditional deletion of neurexins dysregulates neurotransmission from dopamine neurons. eLife 2023; 12:e87902. [PMID: 37409563 PMCID: PMC10409506 DOI: 10.7554/elife.87902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 07/02/2023] [Indexed: 07/07/2023] Open
Abstract
Midbrain dopamine (DA) neurons are key regulators of basal ganglia functions. The axonal domain of these neurons is highly complex, with a large subset of non-synaptic release sites and a smaller subset of synaptic terminals from which in addition to DA, glutamate or GABA are also released. The molecular mechanisms regulating the connectivity of DA neurons and their neurochemical identity are unknown. An emerging literature suggests that neuroligins, trans-synaptic cell adhesion molecules, regulate both DA neuron connectivity and neurotransmission. However, the contribution of their major interaction partners, neurexins (Nrxns), is unexplored. Here, we tested the hypothesis that Nrxns regulate DA neuron neurotransmission. Mice with conditional deletion of all Nrxns in DA neurons (DAT::NrxnsKO) exhibited normal basic motor functions. However, they showed an impaired locomotor response to the psychostimulant amphetamine. In line with an alteration in DA neurotransmission, decreased levels of the membrane DA transporter (DAT) and increased levels of the vesicular monoamine transporter (VMAT2) were detected in the striatum of DAT::NrxnsKO mice, along with reduced activity-dependent DA release. Strikingly, electrophysiological recordings revealed an increase of GABA co-release from DA neuron axons in the striatum of these mice. Together, these findings suggest that Nrxns act as regulators of the functional connectivity of DA neurons.
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Affiliation(s)
- Charles Ducrot
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
| | - Gregory de Carvalho
- Department of Anatomy and Neurobiology, School of Medicine, University of California, IrvineIrvineUnited States
| | - Benoît Delignat-Lavaud
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
| | - Constantin VL Delmas
- CERVO Brain Research Centre, Department of Psychiatry and Neurosciences, Faculty of Medicine, Université LavalQuebecCanada
| | - Priyabrata Halder
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
| | - Nicolas Giguère
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
| | - Consiglia Pacelli
- Department of Clinical and Experimental Medicine, University of FoggiaFoggiaItaly
| | - Sriparna Mukherjee
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
| | - Marie-Josée Bourque
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
| | - Martin Parent
- CERVO Brain Research Centre, Department of Psychiatry and Neurosciences, Faculty of Medicine, Université LavalQuebecCanada
| | - Lulu Y Chen
- Department of Anatomy and Neurobiology, School of Medicine, University of California, IrvineIrvineUnited States
| | - Louis-Eric Trudeau
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de MontréalMontréalCanada
- Department of Neurosciences, Faculty of Medicine, Université de MontréalMontréalCanada
- Neural Signaling and Circuitry Research Group (SNC)MontréalCanada
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3
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Lee H, Chofflet N, Liu J, Fan S, Lu Z, Resua Rojas M, Penndorf P, Bailey AO, Russell WK, Machius M, Ren G, Takahashi H, Rudenko G. Designer molecules of the synaptic organizer MDGA1 reveal 3D conformational control of biological function. J Biol Chem 2023; 299:104586. [PMID: 36889589 PMCID: PMC10131064 DOI: 10.1016/j.jbc.2023.104586] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 03/08/2023] Open
Abstract
MDGAs (MAM domain-containing glycosylphosphatidylinositol anchors) are synaptic cell surface molecules that regulate the formation of trans-synaptic bridges between neurexins (NRXNs) and neuroligins (NLGNs), which promote synaptic development. Mutations in MDGAs are implicated in various neuropsychiatric diseases. MDGAs bind NLGNs in cis on the postsynaptic membrane and physically block NLGNs from binding to NRXNs. In crystal structures, the six immunoglobulin (Ig) and single fibronectin III domains of MDGA1 reveal a striking compact, triangular shape, both alone and in complex with NLGNs. Whether this unusual domain arrangement is required for biological function or other arrangements occur with different functional outcomes is unknown. Here, we show that WT MDGA1 can adopt both compact and extended 3D conformations that bind NLGN2. Designer mutants targeting strategic molecular elbows in MDGA1 alter the distribution of 3D conformations while leaving the binding affinity between soluble ectodomains of MDGA1 and NLGN2 intact. In contrast, in a cellular context, these mutants result in unique combinations of functional consequences, including altered binding to NLGN2, decreased capacity to conceal NLGN2 from NRXN1β, and/or suppressed NLGN2-mediated inhibitory presynaptic differentiation, despite the mutations being located far from the MDGA1-NLGN2 interaction site. Thus, the 3D conformation of the entire MDGA1 ectodomain appears critical for its function, and its NLGN-binding site on Ig1-Ig2 is not independent of the rest of the molecule. As a result, global 3D conformational changes to the MDGA1 ectodomain via strategic elbows may form a molecular mechanism to regulate MDGA1 action within the synaptic cleft.
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Affiliation(s)
- Hubert Lee
- Deptartment of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Nicolas Chofflet
- Synapse Development and Plasticity Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Quebec, Canada; Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Shanghua Fan
- Deptartment of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Zhuoyang Lu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Martin Resua Rojas
- Synapse Development and Plasticity Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Quebec, Canada
| | - Patrick Penndorf
- Synapse Development and Plasticity Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Quebec, Canada
| | - Aaron O Bailey
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - William K Russell
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Mischa Machius
- Deptartment of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Hideto Takahashi
- Synapse Development and Plasticity Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Quebec, Canada; Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montréal, Quebec, Canada; Division of Experimental Medicine, McGill University, Montréal, Quebec, Canada.
| | - Gabby Rudenko
- Deptartment of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
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Khoja S, Haile MT, Chen LY. Advances in neurexin studies and the emerging role of neurexin-2 in autism spectrum disorder. Front Mol Neurosci 2023; 16:1125087. [PMID: 36923655 PMCID: PMC10009110 DOI: 10.3389/fnmol.2023.1125087] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/08/2023] [Indexed: 03/02/2023] Open
Abstract
Over the past 3 decades, the prevalence of autism spectrum disorder (ASD) has increased globally from 20 to 28 million cases making ASD the fastest-growing developmental disability in the world. Neurexins are a family of presynaptic cell adhesion molecules that have been increasingly implicated in ASD, as evidenced by genetic mutations in the clinical population. Neurexins function as context-dependent specifiers of synapse properties and critical modulators in maintaining the balance between excitatory and inhibitory transmission (E/I balance). Disrupted E/I balance has long been established as a hallmark of ASD making neurexins excellent starting points for understanding the etiology of ASD. Herein we review neurexin mutations that have been discovered in ASD patients. Further, we discuss distinct synaptic mechanisms underlying the aberrant neurotransmission and behavioral deficits observed in different neurexin mouse models, with focus on recent discoveries from the previously overlooked neurexin-2 gene (Nrxn2 in mice and NRXN2 in humans). Hence, the aim of this review is to provide a summary of new synaptic insights into the molecular underpinnings of ASD.
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Affiliation(s)
- Sheraz Khoja
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Mulatwa T Haile
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Lulu Y Chen
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA, United States
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5
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Abstract
Since the discovery of neurexins (Nrxns) as essential and evolutionarily conserved synaptic adhesion molecules, focus has largely centered on their functional contributions to glutamatergic synapses. Recently, significant advances to our understanding of neurexin function at GABAergic synapses have revealed that neurexins can play pleiotropic roles in regulating inhibitory synapse maintenance and function in a brain-region and synapse-specific manner. GABAergic neurons are incredibly diverse, exhibiting distinct synaptic properties, sites of innervation, neuromodulation, and plasticity. Different classes of GABAergic neurons often express distinct repertoires of Nrxn isoforms that exhibit differential alternative exon usage. Further, Nrxn ligands can be differentially expressed and can display synapse-specific localization patterns, which may contribute to the formation of a complex trans-synaptic molecular code that establishes the properties of inhibitory synapse function and properties of local circuitry. In this review, we will discuss how Nrxns and their ligands sculpt synaptic inhibition in a brain-region, cell-type and synapse-specific manner.
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Affiliation(s)
| | - Jason Aoto
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Denver, CO, United States
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Camporesi E, Nilsson J, Vrillon A, Cognat E, Hourregue C, Zetterberg H, Blennow K, Becker B, Brinkmalm A, Paquet C, Brinkmalm G. Quantification of the trans-synaptic partners neurexin-neuroligin in CSF of neurodegenerative diseases by parallel reaction monitoring mass spectrometry. EBioMedicine 2022; 75:103793. [PMID: 34990894 PMCID: PMC8743209 DOI: 10.1016/j.ebiom.2021.103793] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Synaptic proteins are increasingly studied as biomarkers for synaptic dysfunction and loss, which are early and central events in Alzheimer's disease (AD) and strongly correlate with the degree of cognitive decline. In this study, we specifically investigated the synaptic binding partners neurexin (NRXN) and neuroligin (Nlgn) proteins, to assess their biomarker's potential. METHODS we developed a parallel reaction monitoring mass spectrometric method for the simultaneous quantification of NRXNs and Nlgns in cerebrospinal fluid (CSF) of neurodegenerative diseases, focusing on AD. Specifically, NRXN-1α, NRXN-1β, NRXN-2α, NRXN-3α and Nlgn1, Nlgn2, Nlgn3 and Nlgn4 proteins were targeted. FINDINGS The proteins were investigated in a clinical cohort including CSF from controls (n=22), mild cognitive impairment (MCI) due to AD (n=44), MCI due to other conditions (n=46), AD (n=77) and a group of non-AD dementia (n=28). No difference in levels of NRXNs and Nlgns was found between AD (both at dementia and MCI stages) or controls or the non-AD dementia group for any of the targeted proteins. NRXN and Nlgn proteins correlated strongly with each other, but only a weak correlation with the AD core biomarkers and the synaptic biomarkers neurogranin and growth-associated protein 43, was found, possibly reflecting different pathogenic processing at the synapse. INTERPRETATION we conclude that NRXN and Nlgn proteins do not represent suitable biomarkers for synaptic pathology in AD. The panel developed here could aid in future investigations of the potential involvement of NRXNs and Nlgns in synaptic dysfunction in other disorders of the central nervous system. FUNDING a full list of funding can be found under the acknowledgments section.
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Affiliation(s)
- Elena Camporesi
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.
| | - Johanna Nilsson
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Agathe Vrillon
- Université de Paris, Cognitive Neurology Center, GHU Nord APHP Hospital Lariboisière Fernand Widal, Paris, France; Université de Paris, Inserm UMR S11-44 Therapeutic Optimization in Neuropsychopharmacology, Paris, France
| | - Emmanuel Cognat
- Université de Paris, Cognitive Neurology Center, GHU Nord APHP Hospital Lariboisière Fernand Widal, Paris, France; Université de Paris, Inserm UMR S11-44 Therapeutic Optimization in Neuropsychopharmacology, Paris, France
| | - Claire Hourregue
- Université de Paris, Cognitive Neurology Center, GHU Nord APHP Hospital Lariboisière Fernand Widal, Paris, France
| | - Henrik Zetterberg
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden; UK Dementia Research Institute at UCL, London, UK; Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK; Hong Kong Center for Neurodegenerative Diseases, Hong Kong, China
| | - Kaj Blennow
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Bruno Becker
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Ann Brinkmalm
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Claire Paquet
- Université de Paris, Cognitive Neurology Center, GHU Nord APHP Hospital Lariboisière Fernand Widal, Paris, France; Université de Paris, Inserm UMR S11-44 Therapeutic Optimization in Neuropsychopharmacology, Paris, France
| | - Gunnar Brinkmalm
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
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Blockus H, Rolotti SV, Szoboszlay M, Peze-Heidsieck E, Ming T, Schroeder A, Apostolo N, Vennekens KM, Katsamba PS, Bahna F, Mannepalli S, Ahlsen G, Honig B, Shapiro L, de Wit J, Losonczy A, Polleux F. Synaptogenic activity of the axon guidance molecule Robo2 underlies hippocampal circuit function. Cell Rep 2021; 37:109828. [PMID: 34686348 PMCID: PMC8605498 DOI: 10.1016/j.celrep.2021.109828] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 07/06/2021] [Accepted: 09/22/2021] [Indexed: 01/03/2023] Open
Abstract
Synaptic connectivity within adult circuits exhibits a remarkable degree of cellular and subcellular specificity. We report that the axon guidance receptor Robo2 plays a role in establishing synaptic specificity in hippocampal CA1. In vivo, Robo2 is present and required postsynaptically in CA1 pyramidal neurons (PNs) for the formation of excitatory (E) but not inhibitory (I) synapses, specifically in proximal but not distal dendritic compartments. In vitro approaches show that the synaptogenic activity of Robo2 involves a trans-synaptic interaction with presynaptic Neurexins, as well as binding to its canonical extracellular ligand Slit. In vivo 2-photon Ca2+ imaging of CA1 PNs during spatial navigation in awake behaving mice shows that preventing Robo2-dependent excitatory synapse formation cell autonomously during development alters place cell properties of adult CA1 PNs. Our results identify a trans-synaptic complex linking the establishment of synaptic specificity to circuit function.
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Affiliation(s)
- Heike Blockus
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Sebi V Rolotti
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Miklos Szoboszlay
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Eugénie Peze-Heidsieck
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Tiffany Ming
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Anna Schroeder
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Nuno Apostolo
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Kristel M Vennekens
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Phinikoula S Katsamba
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Fabiana Bahna
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Seetha Mannepalli
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Goran Ahlsen
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Barry Honig
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Lawrence Shapiro
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Joris de Wit
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
| | - Franck Polleux
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
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Innocenzi E, Cariati I, De Domenico E, Tiberi E, D'Arcangelo G, Verdile V, Paronetto MP, Tancredi V, Barchi M, Rossi P, Sette C, Grimaldi P. Aerobic Exercise Induces Alternative Splicing of Neurexins in Frontal Cortex. J Funct Morphol Kinesiol 2021; 6. [PMID: 34072692 DOI: 10.3390/jfmk6020048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/24/2021] [Accepted: 05/26/2021] [Indexed: 12/02/2022] Open
Abstract
Aerobic exercise (AE) is known to produce beneficial effects on brain health by improving plasticity, connectivity, and cognitive functions, but the underlying molecular mechanisms are still limited. Neurexins (Nrxns) are a family of presynaptic cell adhesion molecules that are important in synapsis formation and maturation. In vertebrates, three-neurexin genes (NRXN1, NRXN2, and NRXN3) have been identified, each encoding for α and β neurexins, from two independent promoters. Moreover, each Nrxns gene (1-3) has several alternative exons and produces many splice variants that bind to a large variety of postsynaptic ligands, playing a role in trans-synaptic specification, strength, and plasticity. In this study, we investigated the impact of a continuous progressive (CP) AE program on alternative splicing (AS) of Nrxns on two brain regions: frontal cortex (FC) and hippocampus. We showed that exercise promoted Nrxns1-3 AS at splice site 4 (SS4) both in α and β isoforms, inducing a switch from exon-excluded isoforms (SS4-) to exon-included isoforms (SS4+) in FC but not in hippocampus. Additionally, we showed that the same AE program enhanced the expression level of other genes correlated with synaptic function and plasticity only in FC. Altogether, our findings demonstrated the positive effect of CP AE on FC in inducing molecular changes underlying synaptic plasticity and suggested that FC is possibly a more sensitive structure than hippocampus to show molecular changes.
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Abstract
Neurexins are presynaptic cell-adhesion molecules essential for synaptic function that are expressed in thousands of alternatively spliced isoforms. Recent studies suggested that alternative splicing at splice site 4 (SS4) of Nrxn1 is tightly regulated by an activity-dependent mechanism. Given that Nrxn1 alternative splicing at SS4 controls NMDA-receptor-mediated synaptic responses, activity-dependent SS4 alternative splicing would suggest a new synaptic plasticity mechanism. However, conflicting results confound the assessment of neurexin alternative splicing, prompting us to re-evaluate this issue. We find that in cortical cultures, membrane depolarization by elevated extracellular K+-concentrations produced an apparent shift in Nrxn1-SS4 alternative splicing by inducing neuronal but not astroglial cell death, resulting in persistent astroglial Nrxn1-SS4+ expression and decreased neuronal Nrxn1-SS4- expression. in vivo, systemic kainate-induced activation of neurons in the hippocampus produced no changes in Nrxn1-SS4 alternative splicing. Moreover, focal kainate injections into the mouse cerebellum induced small changes in Nrxn1-SS4 alternative splicing that, however, were associated with large decreases in Nrxn1 expression and widespread DNA damage. Our results suggest that although Nrxn1-SS4 alternative splicing may represent a mechanism of activity-dependent synaptic plasticity, common procedures for testing this hypothesis are prone to artifacts, and more sophisticated approaches will be necessary to test this important question.
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Affiliation(s)
- Kif Liakath-Ali
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, United States
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, United States
| | - Thomas C. Südhof
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, United States
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, United States
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Fan S, Gangwar SP, Machius M, Rudenko G. Interplay between hevin, SPARC, and MDGAs: Modulators of neurexin-neuroligin transsynaptic bridges. Structure 2021; 29:664-678.e6. [PMID: 33535026 DOI: 10.1016/j.str.2021.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/20/2020] [Accepted: 01/08/2021] [Indexed: 12/18/2022]
Abstract
Hevin is secreted by astrocytes and its synaptogenic effects are antagonized by the related protein, SPARC. Hevin stabilizes neurexin-neuroligin transsynaptic bridges in vivo. A third protein, membrane-tethered MDGA, blocks these bridges. Here, we reveal the molecular underpinnings of a regulatory network formed by this trio of proteins. The hevin FS-EC structure differs from SPARC, in that the EC domain appears rearranged around a conserved core. The FS domain is structurally conserved and it houses nanomolar affinity binding sites for neurexin and neuroligin. SPARC also binds neurexin and neuroligin, competing with hevin, so its antagonist action is rooted in its shortened N-terminal region. Strikingly, the hevin FS domain competes with MDGA for an overlapping binding site on neuroligin, while the hevin EC domain binds the extracellular matrix protein collagen (like SPARC), so that this trio of proteins can regulate neurexin-neuroligin transsynaptic bridges and also extracellular matrix interactions, impacting synapse formation and ultimately neural circuits.
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11
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Luo F, Sclip A, Jiang M, Südhof TC. Neurexins cluster Ca 2+ channels within the presynaptic active zone. EMBO J 2020; 39:e103208. [PMID: 32134527 DOI: 10.15252/embj.2019103208] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 02/05/2023] Open
Abstract
To achieve ultrafast neurotransmission, neurons assemble synapses with highly organized presynaptic and postsynaptic nanomachines that are aligned by synaptic adhesion molecules. How functional assembly of presynaptic active zones is controlled via trans-synaptic interactions remains unknown. Here, we conditionally deleted all three neurexin adhesion molecules from presynaptic neurons of the calyx of Held in the mouse auditory system, a model synapse that allows precise biophysical analyses of synaptic properties. The pan-neurexin deletion had no effect on synapse development or the basic release machinery, but dramatically impaired fast neurotransmitter release. The overall properties of presynaptic calcium ion channels appeared normal, as reflected by the similar characteristics of calcium currents recorded at the nerve terminals. However, the pan-neurexin deletion significantly impaired the tight coupling of calcium influx to exocytosis, thereby suppressing neurotransmitter release. Furthermore, the pan-neurexin deletion reduced the function of calcium-activated BK potassium channels, whose activation depends on their tight association with presynaptic calcium channels. Together, these results suggest that neurexins perform a major function at the calyx synapse in coupling presynaptic calcium channels to release sites.
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Affiliation(s)
- Fujun Luo
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical School, Stanford, CA, USA
| | - Alessandra Sclip
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical School, Stanford, CA, USA
| | - Man Jiang
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical School, Stanford, CA, USA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical School, Stanford, CA, USA
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12
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Abstract
Synapses are intercellular junctions specialized for fast, point-to-point information transfer from a presynaptic neuron to a postsynaptic cell. At a synapse, a presynaptic terminal secretes neurotransmitters via a canonical release machinery, while a postsynaptic specialization senses neurotransmitters via diverse receptors. Synaptic junctions are likely organized by trans-synaptic cell-adhesion molecules (CAMs) that bidirectionally orchestrate synapse formation, restructuring, and elimination. Many candidate synaptic CAMs were described, but which CAMs are central actors and which are bystanders remains unclear. Moreover, multiple genes encoding synaptic CAMs were linked to neuropsychiatric disorders, but the mechanisms involved are unresolved. Here, I propose that engagement of multifarious synaptic CAMs produces parallel trans-synaptic signals that mediate the establishment, organization, and plasticity of synapses, thereby controlling information processing by neural circuits. Among others, this hypothesis implies that synapse formation can be understood in terms of inter- and intracellular signaling, and that neuropsychiatric disorders involve an impairment in such signaling.
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Affiliation(s)
- Thomas C Südhof
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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13
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Dai J, Aoto J, Südhof TC. Alternative Splicing of Presynaptic Neurexins Differentially Controls Postsynaptic NMDA and AMPA Receptor Responses. Neuron 2019; 102:993-1008.e5. [PMID: 31005376 PMCID: PMC6554035 DOI: 10.1016/j.neuron.2019.03.032] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/20/2019] [Accepted: 03/19/2019] [Indexed: 12/11/2022]
Abstract
AMPA- and NMDA-type glutamate receptors mediate distinct postsynaptic signals that differ characteristically among synapses. How postsynaptic AMPA- and NMDA-receptor levels are regulated, however, remains unclear. Using newly generated conditional knockin mice that enable genetic control of neurexin alternative splicing, we show that in hippocampal synapses, alternative splicing of presynaptic neurexin-1 at splice site 4 (SS4) dramatically enhanced postsynaptic NMDA-receptor-mediated, but not AMPA-receptor-mediated, synaptic responses without altering synapse density. In contrast, alternative splicing of neurexin-3 at SS4 suppressed AMPA-receptor-mediated, but not NMDA-receptor-mediated, synaptic responses, while alternative splicing of neurexin-2 at SS4 had no effect on NMDA- or AMPA-receptor-mediated responses. Presynaptic overexpression of the neurexin-1β and neurexin-3β SS4+ splice variants, but not of their SS4- splice variants, replicated the respective SS4+ knockin phenotypes. Thus, different neurexins perform distinct nonoverlapping functions at hippocampal synapses that are independently regulated by alternative splicing. These functions transsynaptically control NMDA and AMPA receptors, thereby mediating presynaptic control of postsynaptic responses.
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Affiliation(s)
- Jinye Dai
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305, USA
| | - Jason Aoto
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305, USA
| | - Thomas C Südhof
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305, USA.
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Brockhaus J, Schreitmüller M, Repetto D, Klatt O, Reissner C, Elmslie K, Heine M, Missler M. α- Neurexins Together with α2δ-1 Auxiliary Subunits Regulate Ca 2+ Influx through Ca v2.1 Channels. J Neurosci 2018; 38:8277-94. [PMID: 30104341 DOI: 10.1523/JNEUROSCI.0511-18.2018] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/03/2018] [Accepted: 07/10/2018] [Indexed: 11/21/2022] Open
Abstract
Action potential-evoked neurotransmitter release is impaired in knock-out neurons lacking synaptic cell-adhesion molecules α-neurexins (αNrxns), the extracellularly longer variants of the three vertebrate Nrxn genes. Ca2+ influx through presynaptic high-voltage gated calcium channels like the ubiquitous P/Q-type (CaV2.1) triggers release of fusion-ready vesicles at many boutons. α2δ Auxiliary subunits regulate trafficking and kinetic properties of CaV2.1 pore-forming subunits but it has remained unclear if this involves αNrxns. Using live cell imaging with Ca2+ indicators, we report here that the total presynaptic Ca2+ influx in primary hippocampal neurons of αNrxn triple knock-out mice of both sexes is reduced and involved lower CaV2.1-mediated transients. This defect is accompanied by lower vesicle release, reduced synaptic abundance of CaV2.1 pore-forming subunits, and elevated surface mobility of α2δ-1 on axons. Overexpression of Nrxn1α in αNrxn triple knock-out neurons is sufficient to restore normal presynaptic Ca2+ influx and synaptic vesicle release. Moreover, coexpression of Nrxn1α together with α2δ-1 subunits facilitates Ca2+ influx further but causes little augmentation together with a different subunit, α2δ-3, suggesting remarkable specificity. Expression of defined recombinant CaV2.1 channels in heterologous cells validates and extends the findings from neurons. Whole-cell patch-clamp recordings show that Nrxn1α in combination with α2δ-1, but not with α2δ-3, facilitates Ca2+ currents of recombinant CaV2.1 without altering channel kinetics. These results suggest that presynaptic Nrxn1α acts as a positive regulator of Ca2+ influx through CaV2.1 channels containing α2δ-1 subunits. We propose that this regulation represents an important way for neurons to adjust synaptic strength.SIGNIFICANCE STATEMENT Synaptic transmission between neurons depends on the fusion of neurotransmitter-filled vesicles with the presynaptic membrane, which subsequently activates postsynaptic receptors. Influx of calcium ions into the presynaptic terminal is the key step to trigger vesicle release and involves different subtypes of voltage-gated calcium channels. We study the regulation of calcium channels by neurexins, a family of synaptic cell-adhesion molecules that are essential for many synapse properties. Using optical measurements of calcium influx in cultured neurons and electrophysiological recordings of calcium currents from recombinant channels, we show that a major neurexin variant facilitates calcium influx through P/Q-type channels by interacting with their α2δ-1 auxiliary subunits. These results propose a novel way how neurons can modulate the strength of distinct synapses.
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Seigneur E, Südhof TC. Genetic Ablation of All Cerebellins Reveals Synapse Organizer Functions in Multiple Regions Throughout the Brain. J Neurosci 2018; 38:4774-90. [PMID: 29691328 DOI: 10.1523/JNEUROSCI.0360-18.2018] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/27/2018] [Accepted: 04/16/2018] [Indexed: 01/26/2023] Open
Abstract
Cerebellins are synaptic organizer molecules that bind to presynaptic neurexins and postsynaptic receptors. They are well studied in the cerebellum, but three of the four cerebellins (Cbln1, Cbln2, and Cbln4) are also broadly expressed outside of the cerebellum, suggesting that they perform general functions throughout the brain. Here, we generated male and female constitutive single (KO), double KO (dKO), and triple KO (tKO) mice of Cbln1, Cbln2, and Cbln4. We found that all constitutive cerebellin-deficient mice were viable and fertile, suggesting that cerebellins are not essential for survival. Cbln1/2 dKO mice exhibited salience-induced seizures that were aggravated in Cbln1/2/4 tKO mice, suggesting that all cerebellins contribute to brain function. As described previously, Cbln1 KO mice displayed major motor impairments that were aggravated by additional KO of Cbln2. Strikingly, the Cbln1/2 dKO did not cause alterations in synapse density in the hippocampus of young adult (1- and 2-month-old) mice, but produced a selective ∼50% decrease in hippocampal synapse density in the stratum lacunosum moleculare of the CA1 region and in the dentate gyrus of aging, 6-month-old mice. A similar decrease in excitatory synapse density was observed in the striatum and retrosplenial cortex. Behaviorally, the Cbln1 KO produced dramatic changes in motor behaviors that were partly aggravated by additional deletion of Cbln2 and/or Cbln4. Our results show that cerebellins are not essential for survival and do not contribute to initial synapse formation, but perform multiple functions throughout the brain; as a consequence, their ablation results in a delayed loss of synapses and in behavioral impairments.SIGNIFICANCE STATEMENT Cerebellins (Cbln1-4) are trans-synaptic cell adhesion molecules. In the cerebellum, Cbln1 functions as a bidirectional organizer of parallel fiber-Purkinje cell synapses by binding to presynaptic neurexins and postsynaptic GluRδ2. Little is known about the function of cerebellins outside of the cerebellum; therefore, the present study used single, double, and triple constitutive KO mice of Cbln1, Cbln2, and Cbln4 to analyze the overall function of cerebellins. We show that cerebellins act as important synaptic organizers in specific subsets of neurons and likely contribute to many different brain functions. We also show that cerebellins are not initially required for synapse formation, but rather for specification and long-term synapse maintenance and demonstrate that all cerebellins, not just Cbln1, contribute to brain function.
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Servián-Morilla E, Robles-Lanuza E, Sánchez-Hidalgo AC, Camacho-Garcia RJ, Paez-Gomez JA, Mavillard F, Saura CA, Martinez-Mir A, Scholl FG. Proteolytic Processing of Neurexins by Presenilins Sustains Synaptic Vesicle Release. J Neurosci 2018; 38:901-17. [PMID: 29229705 DOI: 10.1523/JNEUROSCI.1357-17.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 11/03/2017] [Accepted: 11/26/2017] [Indexed: 11/21/2022] Open
Abstract
Proteolytic processing of synaptic adhesion components can accommodate the function of synapses to activity-dependent changes. The adhesion system formed by neurexins (Nrxns) and neuroligins (Nlgns) bidirectionally orchestrate the function of presynaptic and postsynaptic terminals. Previous studies have shown that presenilins (PS), components of the gamma-secretase complex frequently mutated in familial Alzheimer's disease, clear from glutamatergic terminals the accumulation of Nrxn C-terminal fragments (Nrxn-CTF) generated by ectodomain shedding. Here, we characterized the synaptic consequences of the proteolytic processing of Nrxns in cultured hippocampal neurons from mice and rats of both sexes. We show that activation of presynaptic Nrxns with postsynaptic Nlgn1 or inhibition of ectodomain shedding in axonal Nrxn1-β increases presynaptic release at individual terminals, likely reflecting an increase in the number of functional release sites. Importantly, inactivation of PS inhibits presynaptic release downstream of Nrxn activation, leaving synaptic vesicle recruitment unaltered. Glutamate-receptor signaling initiates the activity-dependent generation of Nrxn-CTF, which accumulate at presynaptic terminals lacking PS function. The sole expression of Nrxn-CTF decreases presynaptic release and calcium flux, recapitulating the deficits due to loss of PS function. Our data indicate that inhibition of Nrxn processing by PS is deleterious to glutamatergic function.SIGNIFICANCE STATEMENT To gain insight into the role of presenilins (PS) in excitatory synaptic function, we address the relevance of the proteolytic processing of presynaptic neurexins (Nrxns) in glutamatergic differentiation. Using synaptic fluorescence probes in cultured hippocampal neurons, we report that trans-synaptic activation of Nrxns produces a robust increase in presynaptic calcium levels and neurotransmitter release at individual glutamatergic terminals by a mechanism that depends on normal PS activity. Abnormal accumulation of Nrxn C-terminal fragments resulting from impaired PS activity inhibits presynaptic calcium signal and neurotransmitter release, assigning synaptic defects to Nrxns as a specific PS substrate. These data may provide links into how loss of PS activity inhibits glutamatergic synaptic function in Alzheimer's disease patients.
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17
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Harkin LF, Lindsay SJ, Xu Y, Alzu'bi A, Ferrara A, Gullon EA, James OG, Clowry GJ. Neurexins 1-3 Each Have a Distinct Pattern of Expression in the Early Developing Human Cerebral Cortex. Cereb Cortex 2017; 27:216-232. [PMID: 28013231 PMCID: PMC5654756 DOI: 10.1093/cercor/bhw394] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/16/2016] [Accepted: 12/02/2016] [Indexed: 12/17/2022] Open
Abstract
Neurexins (NRXNs) are presynaptic terminal proteins and candidate neurodevelopmental disorder susceptibility genes; mutations presumably upset synaptic stabilization and function. However, analysis of human cortical tissue samples by RNAseq and quantitative real-time PCR at 8-12 postconceptional weeks, prior to extensive synapse formation, showed expression of all three NRXNs as well as several potential binding partners. However, the levels of expression were not identical; NRXN1 increased with age and NRXN2 levels were consistently higher than for NRXN3. Immunohistochemistry for each NRXN also revealed different expression patterns at this stage of development. NRXN1 and NRXN3 immunoreactivity was generally strongest in the cortical plate and increased in the ventricular zone with age, but was weak in the synaptogenic presubplate (pSP) and marginal zone. On the other hand, NRXN2 colocalized with synaptophysin in neurites of the pSP, but especially with GAP43 and CASK in growing axons of the intermediate zone. Alternative splicing modifies the role of NRXNs and we found evidence by RNAseq for exon skipping at splice site 4 and concomitant expression of KHDBRS proteins which control this splicing. NRXN2 may play a part in early cortical synaptogenesis, but NRXNs could have diverse roles in development including axon guidance, and intercellular communication between proliferating cells and/or migrating neurons.
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Affiliation(s)
- Lauren F Harkin
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
- Present address: School of Healthcare Science, Manchester Metropolitan University, Manchester, M1 5GD, UK
| | - Susan J Lindsay
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
| | - Yaobo Xu
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
- Present address: Wellcome Trust, Sanger Institute, Cambridge, CB10 1SA, UK
| | - Ayman Alzu'bi
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
| | - Alexandra Ferrara
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
| | - Emily A Gullon
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
| | - Owen G James
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK
- Present address: MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, EH16 4UU, UK
| | - Gavin J Clowry
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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18
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Missler M, Südhof TC. Neurexophilins form a conserved family of neuropeptide-like glycoproteins. J Neurosci 1998; 18:3630-8. [PMID: 9570794 PMCID: PMC6793134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/1998] [Revised: 02/27/1998] [Accepted: 02/27/1998] [Indexed: 02/07/2023] Open
Abstract
Neurexophilin was discovered as a neuronal glycoprotein that is copurified with neurexin Ialpha during affinity chromatography on immobilized alpha-latrotoxin (Petrenko et al., 1996). We have now investigated how neurexophilin interacts with neurexins, whether it is post-translationally processed by site-specific cleavage similar to neuropeptides, and whether related neuropeptide-like proteins are expressed in brain. Our data show that mammalian brains contain four genes for neurexophilins the products of which share a common structure composed of five domains: an N-terminal signal peptide, a variable N-terminal domain, a highly conserved central domain that is N-glycosylated, a short linker region, and a conserved C-terminal domain that is cysteine-rich. When expressed in pheochromocytoma (PC12) cells with a replication-deficient adenovirus, neurexophilin 1 was rapidly N-glycosylated and then slowly processed to a smaller mature form, probably by endoproteolytic cleavage. Similar expression experiments in other neuron-like cells and in fibroblastic cells revealed that N-glycosylation of neurexophilin 1 occurred in all cell types tested, whereas proteolytic processing was observed only in neuron-like cells. Finally, only recombinant neurexin Ialpha and IIIalpha but not neurexin Ibeta interacted with neurexophilin 1 and were preferentially bound to the processed mature form of neurexophilin. Together our data demonstrate that neurexophilins form a family of related glycoproteins that are proteolytically processed after synthesis and bind to alpha-neurexins. The structure and characteristics of neurexophilins indicate that they function as neuropeptides that may signal via alpha-neurexins.
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Affiliation(s)
- M Missler
- Howard Hughes Medical Institute and Department of Molecular Genetics, The University of Texas Southwestern Medical School, Dallas, Texas 75235, USA
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Petrenko AG, Ullrich B, Missler M, Krasnoperov V, Rosahl TW, Südhof TC. Structure and evolution of neurexophilin. J Neurosci 1996; 16:4360-9. [PMID: 8699246 PMCID: PMC6578849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Using affinity chromatography on immobilized alpha-latrotoxin, we have purified a novel 29 kDa protein, neurexophilin, in a complex with neurexin l alpha. Cloning revealed that rat and bovine neurexophilins are composed of N-terminal signal peptides, nonconserved N-terminal domains (20% identity over 80 residues), and highly homologous C-terminal sequences (85% identity over 169 residues). Analysis of genomic clones from mice identified two distinct neurexophilin genes, one of which is more homologous to rat neurexophilin and the other to bovine neurexophilin. The first neurexophilin gene is expressed abundantly in adult rat and mouse brain, whereas no mRNA corresponding to the second gene was detected in rodents despite its abundant expression in bovine brain, suggesting that rodents and cattle primarily express distinct neurexophilin genes. RNA blots and in situ hybridizations revealed that neurexophilin is expressed in adult rat brain at high levels only in a scattered subpopulation of neurons that probably represent inhibitory interneurons; by contrast, neurexins are expressed in all neurons. Neurexophilin contains a signal sequence and is N-glycosylated at multiple sites, suggesting that it is secreted and binds to the extracellular domain of neurexin l alpha. This hypothesis was confirmed by binding recombinant neurexophilin to the extracellular domains of neurexin l alpha. Together our data suggest that neurexophilin constitutes a secreted glycoprotein that is synthesized in a subclass of neurons and may be a ligand for neurexins.
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Affiliation(s)
- A G Petrenko
- Howard Hughes Medical Institute, University of Texas Southwestern Medical School, Dallas, Texas 75235, USA
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