1
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Kim S, Jang G, Kim H, Lim D, Han KA, Um JW, Ko J. MDGAs perform activity-dependent synapse type-specific suppression via distinct extracellular mechanisms. Proc Natl Acad Sci U S A 2024; 121:e2322978121. [PMID: 38900791 PMCID: PMC11214077 DOI: 10.1073/pnas.2322978121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 05/15/2024] [Indexed: 06/22/2024] Open
Abstract
MDGA (MAM domain containing glycosylphosphatidylinositol anchor) family proteins were previously identified as synaptic suppressive factors. However, various genetic manipulations have yielded often irreconcilable results, precluding precise evaluation of MDGA functions. Here, we found that, in cultured hippocampal neurons, conditional deletion of MDGA1 and MDGA2 causes specific alterations in synapse numbers, basal synaptic transmission, and synaptic strength at GABAergic and glutamatergic synapses, respectively. Moreover, MDGA2 deletion enhanced both N-methyl-D-aspartate (NMDA) receptor- and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor-mediated postsynaptic responses. Strikingly, ablation of both MDGA1 and MDGA2 abolished the effect of deleting individual MDGAs that is abrogated by chronic blockade of synaptic activity. Molecular replacement experiments further showed that MDGA1 requires the meprin/A5 protein/PTPmu (MAM) domain, whereas MDGA2 acts via neuroligin-dependent and/or MAM domain-dependent pathways to regulate distinct postsynaptic properties. Together, our data demonstrate that MDGA paralogs act as unique negative regulators of activity-dependent postsynaptic organization at distinct synapse types, and cooperatively contribute to adjustment of excitation-inhibition balance.
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Affiliation(s)
- Seungjoon Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
- Center for Synapse Diversity and Specificity, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
| | - Gyubin Jang
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
- Center for Synapse Diversity and Specificity, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
| | - Hyeonho Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
- Center for Synapse Diversity and Specificity, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
| | - Dongseok Lim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
| | - Kyung Ah Han
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
- Center for Synapse Diversity and Specificity, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
| | - Ji Won Um
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
- Center for Synapse Diversity and Specificity, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
| | - Jaewon Ko
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
- Center for Synapse Diversity and Specificity, Daegu Gyeongbuk Institute of Science and Technology, Daegu42988, Korea
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2
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Sell GL, Barrow SL, McAllister AK. Glutamate signaling and neuroligin/neurexin adhesion play opposing roles that are mediated by major histocompatibility complex I molecules in cortical synapse formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.05.583626. [PMID: 38496590 PMCID: PMC10942384 DOI: 10.1101/2024.03.05.583626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Although neurons release neurotransmitter before contact, the role for this release in synapse formation remains unclear. Cortical synapses do not require synaptic vesicle release for formation 1-4 , yet glutamate clearly regulates glutamate receptor trafficking 5,6 and induces spine formation 7-11 . Using a culture system to dissect molecular mechanisms, we found that glutamate rapidly decreases synapse density specifically in young cortical neurons in a local and calcium-dependent manner through decreasing NMDAR transport and surface expression as well as co-transport with neuroligin (NL1). Adhesion between NL1 and neurexin 1 protects against this glutamate-induced synapse loss. Major histocompatibility I (MHCI) molecules are required for the effects of glutamate in causing synapse loss through negatively regulating NL1 levels. Thus, like acetylcholine at the NMJ, glutamate acts as a dispersal signal for NMDARs and causes rapid synapse loss unless opposed by NL1-mediated trans-synaptic adhesion. Together, glutamate, MHCI and NL1 mediate a novel form of homeostatic plasticity in young neurons that induces rapid changes in NMDARs to regulate when and where nascent glutamatergic synapses are formed.
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3
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de Arce KP, Ribic A, Chowdhury D, Watters K, Thompson GJ, Sanganahalli BG, Lippard ETC, Rohlmann A, Strittmatter SM, Missler M, Hyder F, Biederer T. Concerted roles of LRRTM1 and SynCAM 1 in organizing prefrontal cortex synapses and cognitive functions. Nat Commun 2023; 14:459. [PMID: 36709330 PMCID: PMC9884278 DOI: 10.1038/s41467-023-36042-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/13/2023] [Indexed: 01/29/2023] Open
Abstract
Multiple trans-synaptic complexes organize synapse development, yet their roles in the mature brain and cooperation remain unclear. We analyzed the postsynaptic adhesion protein LRRTM1 in the prefrontal cortex (PFC), a region relevant to cognition and disorders. LRRTM1 knockout (KO) mice had fewer synapses, and we asked whether other synapse organizers counteract further loss. This determined that the immunoglobulin family member SynCAM 1 controls synapse number in PFC and was upregulated upon LRRTM1 loss. Combined LRRTM1 and SynCAM 1 deletion substantially lowered dendritic spine number in PFC, but not hippocampus, more than the sum of single KO impairments. Their cooperation extended presynaptically, and puncta of Neurexins, LRRTM1 partners, were less abundant in double KO (DKO) PFC. Electrophysiology and fMRI demonstrated aberrant neuronal activity in DKO mice. Further, DKO mice were impaired in social interactions and cognitive tasks. Our results reveal concerted roles of LRRTM1 and SynCAM 1 across synaptic, network, and behavioral domains.
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Affiliation(s)
- Karen Perez de Arce
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
- Neuroscience Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Adema Ribic
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
- Department of Psychology, University of Virginia, Charlottesville, VA, USA
| | | | - Katherine Watters
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Garth J Thompson
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- iHuman Institute, ShanghaiTech University, Shanghai, China
| | | | - Elizabeth T C Lippard
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- Department of Psychiatry, University of Texas, Austin, TX, USA
| | - Astrid Rohlmann
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
| | - Stephen M Strittmatter
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
| | - Fahmeed Hyder
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Thomas Biederer
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA.
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
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4
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Van Berkel AA, Koopmans F, Gonzalez-Lozano MA, Lammertse HCA, Feringa F, Bryois J, Sullivan PF, Smit AB, Toonen RF, Verhage M. Dysregulation of synaptic and developmental transcriptomic/proteomic profiles upon depletion of MUNC18-1. eNeuro 2022; 9:ENEURO.0186-22.2022. [PMID: 36257704 PMCID: PMC9668351 DOI: 10.1523/eneuro.0186-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/27/2022] [Accepted: 07/14/2022] [Indexed: 11/23/2022] Open
Abstract
Absence of presynaptic protein MUNC18-1 (gene: Stxbp1) leads to neuronal cell death at an immature stage before synapse formation. Here, we performed transcriptomic and proteomic profiling of immature Stxbp1 knockout (KO) cells to discover which cellular processes depend on MUNC18-1. Hippocampi of Stxbp1 KO mice showed cell-type specific dysregulation of 2123 transcripts primarily related to synaptic transmission and immune response. To further investigate direct, neuron-specific effects of MUNC18-1 depletion, a proteomic screen was performed on murine neuronal cultures at two developmental timepoints prior to onset of neuron degeneration. 399 proteins were differentially expressed, which were primarily involved in synaptic function (especially synaptic vesicle exocytosis) and neuron development. We further show that many of the downregulated proteins upon loss of MUNC18-1 are normally upregulated during this developmental stage. Thus, absence of MUNC18-1 extensively dysregulates the transcriptome and proteome, primarily affecting synaptic and developmental profiles. Lack of synaptic activity is unlikely to underlie these effects, as the changes were observed in immature neurons without functional synapses, and minimal overlap was found to activity-dependent proteins. We hypothesize that presence of MUNC18-1 is essential to advance neuron development, serving as a 'checkpoint' for neurons to initiate cell death in its absence.Significance StatementPresynaptic protein MUNC18-1 is essential for neuronal functioning. Pathogenic variants in its gene, STXBP1, are among the most common found in patients with developmental delay and epilepsy. To discern the pathogenesis in these patients, a thorough understanding of MUNC18-1's function in neurons is required. Here, we show that loss of MUNC18-1 results in extensive dysregulation of synaptic and developmental proteins in immature neurons before synapse formation. Many of the downregulated proteins are normally upregulated during this developmental stage. This indicates that MUNC18-1 is a critical regulator of neuronal development, which could play an important role in the pathogenesis of STXBP1 variant carriers.
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Affiliation(s)
- A A Van Berkel
- Dept. Functional Genomics, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
- Functional Genomics, Department of Human Genetics, CNCR, Amsterdam UMC, 1081 HV Amsterdam, The Netherlands
| | - F Koopmans
- Dept. Functional Genomics, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
- Dept. Molecular & Cellular Neurobiology, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - M A Gonzalez-Lozano
- Dept. Molecular & Cellular Neurobiology, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - H C A Lammertse
- Dept. Functional Genomics, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
- Functional Genomics, Department of Human Genetics, CNCR, Amsterdam UMC, 1081 HV Amsterdam, The Netherlands
| | - F Feringa
- Functional Genomics, Department of Human Genetics, CNCR, Amsterdam UMC, 1081 HV Amsterdam, The Netherlands
| | - J Bryois
- Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, Nobels vag 12A, 171 77 Stockholm, Sweden
| | - P F Sullivan
- UNC Center for Psychiatric Genomics, University of North Carolina at Chapel Hill, 101 Manning Drive, Chapel Hill, NC 27599-7160, USA
- Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, Nobels vag 12A, 171 77 Stockholm, Sweden
| | - A B Smit
- Dept. Molecular & Cellular Neurobiology, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - R F Toonen
- Dept. Functional Genomics, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - M Verhage
- Dept. Functional Genomics, CNCR, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
- Functional Genomics, Department of Human Genetics, CNCR, Amsterdam UMC, 1081 HV Amsterdam, The Netherlands
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5
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Dhume SH, Connor SA, Mills F, Tari PK, Au-Yeung SHM, Karimi B, Oku S, Roppongi RT, Kawabe H, Bamji SX, Wang YT, Brose N, Jackson MF, Craig AM, Siddiqui TJ. Distinct but overlapping roles of LRRTM1 and LRRTM2 in developing and mature hippocampal circuits. eLife 2022; 11:64742. [PMID: 35662394 PMCID: PMC9170246 DOI: 10.7554/elife.64742] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 05/20/2022] [Indexed: 01/21/2023] Open
Abstract
LRRTMs are postsynaptic cell adhesion proteins that have region-restricted expression in the brain. To determine their role in the molecular organization of synapses in vivo, we studied synapse development and plasticity in hippocampal neuronal circuits in mice lacking both Lrrtm1 and Lrrtm2. We found that LRRTM1 and LRRTM2 regulate the density and morphological integrity of excitatory synapses on CA1 pyramidal neurons in the developing brain but are not essential for these roles in the mature circuit. Further, they are required for long-term-potentiation in the CA3-CA1 pathway and the dentate gyrus, and for enduring fear memory in both the developing and mature brain. Our data show that LRRTM1 and LRRTM2 regulate synapse development and function in a cell-type and developmental-stage-specific manner, and thereby contribute to the fine-tuning of hippocampal circuit connectivity and plasticity.
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Affiliation(s)
- Shreya H Dhume
- Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Canada.,Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada
| | - Steven A Connor
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada.,Department of Biology, York University, Toronto, Canada
| | - Fergil Mills
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Parisa Karimi Tari
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada.,Department of Biology, York University, Toronto, Canada
| | - Sarah H M Au-Yeung
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Benjamin Karimi
- Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Canada.,Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada
| | - Shinichiro Oku
- Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Canada.,Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada.,Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Reiko T Roppongi
- Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Canada.,Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada
| | - Hiroshi Kawabe
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan.,Department of Gerontology, Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe, Japan.,Department of Pharmacology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Shernaz X Bamji
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Yu Tian Wang
- Division of Neurology, Department of Medicine and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Michael F Jackson
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Canada
| | - Ann Marie Craig
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Tabrez J Siddiqui
- Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Canada.,Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada.,The Children's Hospital Research Institute of Manitoba, Winnipeg, Canada.,Program in Biomedical Engineering, University of Manitoba, Winnipeg, Canada
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6
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Lim D, Kim D, Um JW, Ko J. Reassessing synaptic adhesion pathways. Trends Neurosci 2022; 45:517-528. [DOI: 10.1016/j.tins.2022.04.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 04/12/2022] [Accepted: 04/19/2022] [Indexed: 01/19/2023]
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7
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Abstract
Neurexin-3 is primarily localized in the presynaptic membrane and forms complexes with various ligands located in the postsynaptic membrane. Neurexin-3 has important roles in synapse development and synapse functions. Neurexin-3 mediates excitatory presynaptic differentiation by interacting with leucine-rich-repeat transmembrane neuronal proteins. Meanwhile, neurexin-3 modulates the expression of presynaptic α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors and γ-aminobutyric acid A receptors by interacting with neuroligins at excitatory and inhibitory synapses. Numerous studies have documented the potential contribution of neurexin-3 to neurodegenerative and neuropsychiatric disorders, such as Alzheimer's disease, addiction behaviors, and other diseases, which raises hopes that understanding the mechanisms of neurexin-3 may hold the key to developing new strategies for related illnesses. This review comprehensively covers the literature to provide current knowledge of the structure, function, and clinical role of neurexin-3.
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8
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Kim J, Park D, Seo NY, Yoon TH, Kim GH, Lee SH, Seo J, Um JW, Lee KJ, Ko J. LRRTM3 regulates activity-dependent synchronization of synapse properties in topographically connected hippocampal neural circuits. Proc Natl Acad Sci U S A 2022; 119:e2110196119. [PMID: 35022233 PMCID: PMC8784129 DOI: 10.1073/pnas.2110196119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 12/03/2021] [Indexed: 11/18/2022] Open
Abstract
Synaptic cell-adhesion molecules (CAMs) organize the architecture and properties of neural circuits. However, whether synaptic CAMs are involved in activity-dependent remodeling of specific neural circuits is incompletely understood. Leucine-rich repeat transmembrane protein 3 (LRRTM3) is required for the excitatory synapse development of hippocampal dentate gyrus (DG) granule neurons. Here, we report that Lrrtm3-deficient mice exhibit selective reductions in excitatory synapse density and synaptic strength in projections involving the medial entorhinal cortex (MEC) and DG granule neurons, accompanied by increased neurotransmitter release and decreased excitability of granule neurons. LRRTM3 deletion significantly reduced excitatory synaptic innervation of hippocampal mossy fibers (Mf) of DG granule neurons onto thorny excrescences in hippocampal CA3 neurons. Moreover, LRRTM3 loss in DG neurons significantly decreased mossy fiber long-term potentiation (Mf-LTP). Remarkably, silencing MEC-DG circuits protected against the decrease in the excitatory synaptic inputs onto DG and CA3 neurons, excitability of DG granule neurons, and Mf-LTP in Lrrtm3-deficient mice. These results suggest that LRRTM3 may be a critical factor in activity-dependent synchronization of the topography of MEC-DG-CA3 excitatory synaptic connections. Collectively, our data propose that LRRTM3 shapes the target-specific structural and functional properties of specific hippocampal circuits.
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Affiliation(s)
- Jinhu Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Na-Young Seo
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Taek-Han Yoon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Gyu Hyun Kim
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Sang-Hoon Lee
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
- Brain Research Core Facilities, KBRI, Daegu 41062, Korea
| | - Jinsoo Seo
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Kea Joo Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Neural Circuits Group, Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
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9
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Liouta K, Chabbert J, Benquet S, Tessier B, Studer V, Sainlos M, De Wit J, Thoumine O, Chamma I. Role of regulatory C-terminal motifs in synaptic confinement of LRRTM2. Biol Cell 2021; 113:492-506. [PMID: 34498765 DOI: 10.1111/boc.202100026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 12/25/2022]
Abstract
Leucine Rich Repeat Transmembrane proteins (LRRTMs) are neuronal cell adhesion molecules involved in synapse development and plasticity. LRRTM2 is the most synaptogenic isoform of the family, and its expression is strongly restricted to excitatory synapses in mature neurons. However, the mechanisms by which LRRTM2 is trafficked and stabilized at synapses remain unknown. Here, we examine the role of LRRTM2 intracellular domain on its membrane expression and stabilization at excitatory synapses, using a knock-down strategy combined to single molecule tracking and super-resolution dSTORM microscopy. We show that LRRTM2 operates an important shift in mobility after synaptogenesis in hippocampal neurons. Knock-down of LRRTM2 during synapse formation reduced excitatory synapse density in mature neurons. Deletion of LRRTM2 C-terminal domain abolished the compartmentalization of LRRTM2 in dendrites and disrupted its synaptic enrichment. Furtheremore, we show that LRRTM2 diffusion is increased in the absence of its intracellular domain, and that the protein is more dispersed at synapses. Surprisingly, LRRTM2 confinement at synapses was strongly dependent on a YxxC motif in the C-terminal domain, but was independent of the PDZ-like binding motif ECEV. Finally, the nanoscale organization of LRRTM2 at excitatory synapses depended on its C-terminal domain, with involvement of both the PDZ-binding and YxxC motifs. Altogether, these results demonstrate that LRRTM2 trafficking and enrichment at excitatory synapses are dependent on its intracellular domain.
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Affiliation(s)
- Konstantina Liouta
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Julia Chabbert
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Sebastien Benquet
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Béatrice Tessier
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Vincent Studer
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Matthieu Sainlos
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Joris De Wit
- VIB Center for Brain & Disease Research, Leuven, Belgium.,KU Leuven, Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Ingrid Chamma
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
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10
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Kim S, Park D, Kim J, Kim D, Kim H, Mori T, Jung H, Lee D, Hong S, Jeon J, Tabuchi K, Cheong E, Kim J, Um JW, Ko J. Npas4 regulates IQSEC3 expression in hippocampal somatostatin interneurons to mediate anxiety-like behavior. Cell Rep 2021; 36:109417. [PMID: 34289353 DOI: 10.1016/j.celrep.2021.109417] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 02/11/2021] [Accepted: 06/28/2021] [Indexed: 02/08/2023] Open
Abstract
Activity-dependent GABAergic synapse plasticity is important for normal brain functions, but the underlying molecular mechanisms remain incompletely understood. Here, we show that Npas4 (neuronal PAS-domain protein 4) transcriptionally regulates the expression of IQSEC3, a GABAergic synapse-specific guanine nucleotide-exchange factor for ADP-ribosylation factor (ARF-GEF) that directly interacts with gephyrin. Neuronal activation by an enriched environment induces Npas4-mediated upregulation of IQSEC3 protein specifically in CA1 stratum oriens layer somatostatin (SST)-expressing GABAergic interneurons. SST+ interneuron-specific knockout (KO) of Npas4 compromises synaptic transmission in these GABAergic interneurons, increases neuronal activity in CA1 pyramidal neurons, and reduces anxiety behavior, all of which are normalized by the expression of wild-type IQSEC3, but not a dominant-negative ARF-GEF-inactive mutant, in SST+ interneurons of Npas4-KO mice. Our results suggest that IQSEC3 is a key GABAergic synapse component that is directed by Npas4 and ARF activity, specifically in SST+ interneurons, to orchestrate excitation-to-inhibition balance and control anxiety-like behavior.
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Affiliation(s)
- Seungjoon Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Jinhu Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Dongwook Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Takuma Mori
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano 390-86221, Japan
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Dongsu Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Sookyung Hong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jongcheol Jeon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Katsuhiko Tabuchi
- Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano 390-86221, Japan; Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano 390-8621, Japan
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Jaehoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea.
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea.
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11
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Cui W, Gao N, Dong Z, Shen C, Zhang H, Luo B, Chen P, Comoletti D, Jing H, Wang H, Robinson H, Xiong WC, Mei L. In trans neuregulin3-Caspr3 interaction controls DA axonal bassoon cluster development. Curr Biol 2021; 31:3330-3342.e7. [PMID: 34143959 DOI: 10.1016/j.cub.2021.05.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/19/2021] [Accepted: 05/20/2021] [Indexed: 01/09/2023]
Abstract
Dopamine (DA) transmission is critical to motivation, movement, and emotion. Unlike glutamatergic and GABAergic synapses, the development of DA synapses is less understood. We show that bassoon (BSN) clusters along DA axons in the core of nucleus accumbens (NAcc) were increased in neonatal stages and reduced afterward, suggesting DA synapse elimination. Remarkably, DA neuron-specific ablating neuregulin 3 (NRG3), a protein whose levels correlate with BSN clusters, increased the clusters and impaired DA release and behaviors related to DA transmission. An unbiased screen of transmembrane proteins with the extracellular domain (ECD) of NRG3 identified Caspr3 (contactin associate-like protein 3) as a binding partner. Caspr3 was enriched in striatal medium spiny neurons (MSNs). NRG3 and Caspr3 interact in trans, which was blocked by Caspr3-ECD. Caspr3 null mice displayed phenotypes similar to those in DAT-Nrg3f/f mice in DA axonal BSN clusters and DA transmission. Finally, in vivo disruption of the NRG3-Caspr3 interaction increased BSN clusters. Together, these results demonstrate that DA synapse development is controlled by trans interaction between NRG3 in DA neurons and Caspr3 in MSNs, identifying a novel pair of cell adhesion molecules for brain circuit wiring.
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Affiliation(s)
- Wanpeng Cui
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Nannan Gao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zhaoqi Dong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Chen Shen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Hongsheng Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Bin Luo
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Peng Chen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Davide Comoletti
- School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand; Child Health Institute of New Jersey, and Departments of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ 08901, USA
| | - Hongyang Jing
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Hongsheng Wang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Heath Robinson
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
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12
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Delgado C, Bu L, Zhang J, Liu FY, Sall J, Liang FX, Furley AJ, Fishman GI. Neural cell adhesion molecule is required for ventricular conduction system development. Development 2021; 148:269045. [PMID: 34100064 PMCID: PMC8217711 DOI: 10.1242/dev.199431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/26/2021] [Indexed: 11/23/2022]
Abstract
The most distal portion of the ventricular conduction system (VCS) contains cardiac Purkinje cells (PCs), which are essential for synchronous activation of the ventricular myocardium. Contactin-2 (CNTN2), a member of the immunoglobulin superfamily of cell adhesion molecules (IgSF-CAMs), was previously identified as a marker of the VCS. Through differential transcriptional profiling, we discovered two additional highly enriched IgSF-CAMs in the VCS: NCAM-1 and ALCAM. Immunofluorescence staining showed dynamic expression patterns for each IgSF-CAM during embryonic and early postnatal stages, but ultimately all three proteins became highly enriched in mature PCs. Mice deficient in NCAM-1, but not CNTN2 or ALCAM, exhibited defects in PC gene expression and VCS patterning, as well as cardiac conduction disease. Moreover, using ST8sia2 and ST8sia4 knockout mice, we show that inhibition of post-translational modification of NCAM-1 by polysialic acid leads to disrupted trafficking of sarcolemmal intercalated disc proteins to junctional membranes and abnormal expansion of the extracellular space between apposing PCs. Taken together, our data provide insights into the complex developmental biology of the ventricular conduction system. Summary: The cell adhesion molecule NCAM-1 and its post-translational modification by polysialylation are required for normal formation and function of the specialized ventricular conduction system.
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Affiliation(s)
- Camila Delgado
- Leon H. Charney Division of Cardiology, Department of Medicine, NYU Grossman School of Medicine, NY 10016, USA
| | - Lei Bu
- Leon H. Charney Division of Cardiology, Department of Medicine, NYU Grossman School of Medicine, NY 10016, USA
| | - Jie Zhang
- Leon H. Charney Division of Cardiology, Department of Medicine, NYU Grossman School of Medicine, NY 10016, USA
| | - Fang-Yu Liu
- Leon H. Charney Division of Cardiology, Department of Medicine, NYU Grossman School of Medicine, NY 10016, USA
| | - Joseph Sall
- Microscopy Laboratory, Division of Advanced Research Technologies, NYU Langone Health, NY 10016, USA
| | - Feng-Xia Liang
- Microscopy Laboratory, Division of Advanced Research Technologies, NYU Langone Health, NY 10016, USA
| | - Andrew J Furley
- Department of Biomedical Science, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Glenn I Fishman
- Leon H. Charney Division of Cardiology, Department of Medicine, NYU Grossman School of Medicine, NY 10016, USA
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13
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Chowdhury D, Watters K, Biederer T. Synaptic recognition molecules in development and disease. Curr Top Dev Biol 2021; 142:319-370. [PMID: 33706921 DOI: 10.1016/bs.ctdb.2020.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Synaptic connectivity patterns underlie brain functions. How recognition molecules control where and when neurons form synapses with each other, therefore, is a fundamental question of cellular neuroscience. This chapter delineates adhesion and signaling complexes as well as secreted factors that contribute to synaptic partner recognition in the vertebrate brain. The sections follow a developmental perspective and discuss how recognition molecules (1) guide initial synaptic wiring, (2) provide for the rejection of incorrect partner choices, (3) contribute to synapse specification, and (4) support the removal of inappropriate synapses once formed. These processes involve a rich repertoire of molecular players and key protein families are described, notably the Cadherin and immunoglobulin superfamilies, Semaphorins/Plexins, Leucine-rich repeat containing proteins, and Neurexins and their binding partners. Molecular themes that diversify these recognition systems are defined and highlighted throughout the text, including the neuron-type specific expression and combinatorial action of recognition factors, alternative splicing, and post-translational modifications. Methodological innovations advancing the field such as proteomic approaches and single cell expression studies are additionally described. Further, the chapter highlights the importance of choosing an appropriate brain region to analyze synaptic recognition factors and the advantages offered by laminated structures like the hippocampus or retina. In a concluding section, the profound disease relevance of aberrant synaptic recognition for neurodevelopmental and psychiatric disorders is discussed. Based on the current progress, an outlook is presented on research goals that can further advance insights into how recognition molecules provide for the astounding precision and diversity of synaptic connections.
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Affiliation(s)
| | - Katherine Watters
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States; Neuroscience Graduate Program, Tufts University School of Medicine, Boston, MA, United States
| | - Thomas Biederer
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States.
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14
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Kim HY, Um JW, Ko J. Proper synaptic adhesion signaling in the control of neural circuit architecture and brain function. Prog Neurobiol 2021; 200:101983. [PMID: 33422662 DOI: 10.1016/j.pneurobio.2020.101983] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/23/2020] [Accepted: 12/22/2020] [Indexed: 12/17/2022]
Abstract
Trans-synaptic cell-adhesion molecules are critical for governing various stages of synapse development and specifying neural circuit properties via the formation of multifarious signaling pathways. Recent studies have pinpointed the putative roles of trans-synaptic cell-adhesion molecules in mediating various cognitive functions. Here, we review the literature on the roles of a diverse group of central synaptic organizers, including neurexins (Nrxns), leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs), and their associated binding proteins, in regulating properties of specific type of synapses and neural circuits. In addition, we highlight the findings that aberrant synaptic adhesion signaling leads to alterations in the structures, transmission, and plasticity of specific synapses across diverse brain areas. These results seem to suggest that proper trans-synaptic signaling pathways by Nrxns, LAR-RPTPs, and their interacting network is likely to constitute central molecular complexes that form the basis for cognitive functions, and that these complexes are heterogeneously and complexly disrupted in many neuropsychiatric and neurodevelopmental disorders.
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Affiliation(s)
- Hee Young Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, South Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, South Korea; Core Protein Resources Center, DGIST, Daegu, 42988, South Korea.
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, South Korea.
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15
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LAR-RPTPs Directly Interact with Neurexins to Coordinate Bidirectional Assembly of Molecular Machineries. J Neurosci 2020; 40:8438-8462. [PMID: 33037075 DOI: 10.1523/jneurosci.1091-20.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/27/2020] [Accepted: 09/30/2020] [Indexed: 11/21/2022] Open
Abstract
Neurexins (Nrxns) and LAR-RPTPs (leukocyte common antigen-related protein tyrosine phosphatases) are presynaptic adhesion proteins responsible for organizing presynaptic machineries through interactions with nonoverlapping extracellular ligands. Here, we report that two members of the LAR-RPTP family, PTPσ and PTPδ, are required for the presynaptogenic activity of Nrxns. Intriguingly, Nrxn1 and PTPσ require distinct sets of intracellular proteins for the assembly of specific presynaptic terminals. In addition, Nrxn1α showed robust heparan sulfate (HS)-dependent, high-affinity interactions with Ig domains of PTPσ that were regulated by the splicing status of PTPσ. Furthermore, Nrxn1α WT, but not a Nrxn1α mutant lacking HS moieties (Nrxn1α ΔHS), inhibited postsynapse-inducing activity of PTPσ at excitatory, but not inhibitory, synapses. Similarly, cis expression of Nrxn1α WT, but not Nrxn1α ΔHS, suppressed the PTPσ-mediated maintenance of excitatory postsynaptic specializations in mouse cultured hippocampal neurons. Lastly, genetics analyses using male or female Drosophila Dlar and Dnrx mutant larvae identified epistatic interactions that control synapse formation and synaptic transmission at neuromuscular junctions. Our results suggest a novel synaptogenesis model whereby different presynaptic adhesion molecules combine with distinct regulatory codes to orchestrate specific synaptic adhesion pathways.SIGNIFICANCE STATEMENT We provide evidence supporting the physical interactions of neurexins with leukocyte common-antigen related receptor tyrosine phosphatases (LAR-RPTPs). The availability of heparan sulfates and alternative splicing of LAR-RPTPs regulate the binding affinity of these interactions. A set of intracellular presynaptic proteins is involved in common for Nrxn- and LAR-RPTP-mediated presynaptic assembly. PTPσ triggers glutamatergic and GABAergic postsynaptic differentiation in an alternative splicing-dependent manner, whereas Nrxn1α induces GABAergic postsynaptic differentiation in an alternative splicing-independent manner. Strikingly, Nrxn1α inhibits the glutamatergic postsynapse-inducing activity of PTPσ, suggesting that PTPσ and Nrxn1α might control recruitment of a different pool of postsynaptic machinery. Drosophila orthologs of Nrxns and LAR-RPTPs mediate epistatic interactions in controlling synapse structure and strength at neuromuscular junctions, underscoring the physiological significance in vivo.
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16
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Kim H, Kim D, Kim J, Lee HY, Park D, Kang H, Matsuda K, Sterky FH, Yuzaki M, Kim JY, Choi SY, Ko J, Um JW. Calsyntenin-3 interacts with both α- and β-neurexins in the regulation of excitatory synaptic innervation in specific Schaffer collateral pathways. J Biol Chem 2020; 295:9244-9262. [PMID: 32434929 PMCID: PMC7335786 DOI: 10.1074/jbc.ra120.013077] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/15/2020] [Indexed: 12/13/2022] Open
Abstract
Calsyntenin-3 (Clstn3) is a postsynaptic adhesion molecule that induces presynaptic differentiation via presynaptic neurexins (Nrxns), but whether Nrxns directly bind to Clstn3 has been a matter of debate. Here, using LC-MS/MS-based protein analysis, confocal microscopy, RNAscope assays, and electrophysiological recordings, we show that β-Nrxns directly interact via their LNS domain with Clstn3 and Clstn3 cadherin domains. Expression of splice site 4 (SS4) insert-positive β-Nrxn variants, but not insert-negative variants, reversed the impaired Clstn3 synaptogenic activity observed in Nrxn-deficient neurons. Consistently, Clstn3 selectively formed complexes with SS4-positive Nrxns in vivo Neuron-specific Clstn3 deletion caused significant reductions in number of excitatory synaptic inputs. Moreover, expression of Clstn3 cadherin domains in CA1 neurons of Clstn3 conditional knockout mice rescued structural deficits in excitatory synapses, especially within the stratum radiatum layer. Collectively, our results suggest that Clstn3 links to SS4-positive Nrxns to induce presynaptic differentiation and orchestrate excitatory synapse development in specific hippocampal neural circuits, including Schaffer collateral afferents.
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Affiliation(s)
- Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea
| | - Dongwook Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea
| | - Jinhu Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea
| | - Hee-Yoon Lee
- Department of Neuroscience and Physiology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea
| | - Hyeyeon Kang
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea
| | - Keiko Matsuda
- Department of Physiology, School of Medicine, Keio University, Tokyo, Japan
| | - Fredrik H Sterky
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden; Department of Laboratory Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Michisuke Yuzaki
- Department of Physiology, School of Medicine, Keio University, Tokyo, Japan
| | - Jin Young Kim
- Biomedical Omics Group, Korea Basic Science Institute, Cheongju, Chungbuk, Korea
| | - Se-Young Choi
- Department of Neuroscience and Physiology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea.
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-gun, Daegu, Korea; Core Protein Resources Center, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpoong-Eup, Dalseong-Gun, Daegu, Korea.
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17
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Han KA, Lee HY, Lim D, Shin J, Yoon TH, Liu X, Um JW, Choi SY, Ko J. Receptor protein tyrosine phosphatase delta is not essential for synapse maintenance or transmission at hippocampal synapses. Mol Brain 2020; 13:94. [PMID: 32552840 PMCID: PMC7301452 DOI: 10.1186/s13041-020-00629-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/29/2020] [Indexed: 12/26/2022] Open
Abstract
Members of the leukocyte common antigen-related receptor protein tyrosine phosphatase (LAR-RPTP) family, comprising PTPσ, PTPδ and LAR, are key hubs for presynaptic assembly and differentiation in vertebrate neurons. However, roles of individual LAR-RPTP members have not been investigated using member-specific conditional knockout mice. Here, we show that loss of PTPδ had no overt effect on synapse development in mouse cultured hippocampal neurons. Moreover, loss of PTPδ in presynaptic CA1 hippocampal neurons did not influence neurotransmitter release in subicular pyramidal neurons, suggesting that PTPδ is not critical for presynaptic function in vivo. Our results demonstrate that PTPδ is not essential for synapse maintenance or transmission, at least in the mouse hippocampus, and underscore the importance of using sophisticated genetic approaches to confirm the roles of synaptic proteins.
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Affiliation(s)
- Kyung Ah Han
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea.,Core Protein Resources Center, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea
| | - Hee-Yoon Lee
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, 03080, South Korea
| | - Dongseok Lim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea
| | - Jungsu Shin
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea
| | - Taek Han Yoon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea
| | - Xinran Liu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea.,Core Protein Resources Center, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea
| | - Se-Young Choi
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, 03080, South Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, South Korea.
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18
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Neurons, Glia, Extracellular Matrix and Neurovascular Unit: A Systems Biology Approach to the Complexity of Synaptic Plasticity in Health and Disease. Int J Mol Sci 2020; 21:ijms21041539. [PMID: 32102370 PMCID: PMC7073232 DOI: 10.3390/ijms21041539] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/19/2020] [Accepted: 02/20/2020] [Indexed: 02/06/2023] Open
Abstract
The synaptic cleft has been vastly investigated in the last decades, leading to a novel and fascinating model of the functional and structural modifications linked to synaptic transmission and brain processing. The classic neurocentric model encompassing the neuronal pre- and post-synaptic terminals partly explains the fine-tuned plastic modifications under both pathological and physiological circumstances. Recent experimental evidence has incontrovertibly added oligodendrocytes, astrocytes, and microglia as pivotal elements for synapse formation and remodeling (tripartite synapse) in both the developing and adult brain. Moreover, synaptic plasticity and its pathological counterpart (maladaptive plasticity) have shown a deep connection with other molecular elements of the extracellular matrix (ECM), once considered as a mere extracellular structural scaffold altogether with the cellular glue (i.e., glia). The ECM adds another level of complexity to the modern model of the synapse, particularly, for the long-term plasticity and circuit maintenance. This model, called tetrapartite synapse, can be further implemented by including the neurovascular unit (NVU) and the immune system. Although they were considered so far as tightly separated from the central nervous system (CNS) plasticity, at least in physiological conditions, recent evidence endorsed these elements as structural and paramount actors in synaptic plasticity. This scenario is, as far as speculations and evidence have shown, a consistent model for both adaptive and maladaptive plasticity. However, a comprehensive understanding of brain processes and circuitry complexity is still lacking. Here we propose that a better interpretation of the CNS complexity can be granted by a systems biology approach through the construction of predictive molecular models that enable to enlighten the regulatory logic of the complex molecular networks underlying brain function in health and disease, thus opening the way to more effective treatments.
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19
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Kim S, Kim H, Park D, Kim J, Hong J, Kim JS, Jung H, Kim D, Cheong E, Ko J, Um JW. Loss of IQSEC3 Disrupts GABAergic Synapse Maintenance and Decreases Somatostatin Expression in the Hippocampus. Cell Rep 2020; 30:1995-2005.e5. [PMID: 32049026 DOI: 10.1016/j.celrep.2020.01.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 12/28/2019] [Accepted: 01/16/2020] [Indexed: 12/31/2022] Open
Abstract
Gephyrin interacts with various GABAergic synaptic proteins to organize GABAergic synapse development. Among the multitude of gephyrin-binding proteins is IQSEC3, a recently identified component at GABAergic synapses that acts through its ADP ribosylation factor-guanine nucleotide exchange factor (ARF-GEF) activity to orchestrate GABAergic synapse formation. Here, we show that IQSEC3 knockdown (KD) reduced GABAergic synaptic density in vivo, suggesting that IQSEC3 is required for GABAergic synapse maintenance in vivo. We further show that IQSEC3 KD in the dentate gyrus (DG) increases seizure susceptibility and triggers selective depletion of somatostatin (SST) peptides in the DG hilus in an ARF-GEP activity-dependent manner. Strikingly, selective introduction of SST into SST interneurons in DG-specific IQSEC3-KD mice reverses GABAergic synaptic deficits. Thus, our data suggest that IQSEC3 is required for linking gephyrin-GABAA receptor complexes with ARF-dependent pathways to prevent aberrant, runaway excitation and thereby contributes to the integrity of SST interneurons and proper GABAergic synapse maintenance.
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Affiliation(s)
- Seungjoon Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Jinhu Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Joohyeon Hong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Jae Seong Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Dongwook Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea.
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea; Core Protein Resources Center, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, Korea.
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20
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Kim H, Jung H, Jung H, Kwon SK, Ko J, Um JW. The small GTPase ARF6 regulates GABAergic synapse development. Mol Brain 2020; 13:2. [PMID: 31907062 PMCID: PMC6945580 DOI: 10.1186/s13041-019-0543-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/23/2019] [Indexed: 01/05/2023] Open
Abstract
ADP ribosylation factors (ARFs) are a family of small GTPases composed of six members (ARF1-6) that control various cellular functions, including membrane trafficking and actin cytoskeletal rearrangement, in eukaryotic cells. Among them, ARF1 and ARF6 are the most studied in neurons, particularly at glutamatergic synapses, but their roles at GABAergic synapses have not been investigated. Here, we show that a subset of ARF6 protein is localized at GABAergic synapses in cultured hippocampal neurons. In addition, we found that knockdown (KD) of ARF6, but not ARF1, triggered a reduction in the number of GABAergic synaptic puncta in mature cultured neurons in an ARF activity-dependent manner. ARF6 KD also reduced GABAergic synaptic density in the mouse hippocampal dentate gyrus (DG) region. Furthermore, ARF6 KD in the DG increased seizure susceptibility in an induced epilepsy model. Viewed together, our results suggest that modulating ARF6 and its regulators could be a therapeutic strategy against brain pathologies involving hippocampal network dysfunction, such as epilepsy.
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Affiliation(s)
- Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyunsu Jung
- Division of Life Sciences, Korea University, Seoul, 02841, South Korea.,Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea.
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21
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Karki S, Maksimainen MM, Lehtiö L, Kajander T. Inhibitor screening assay for neurexin-LRRTM adhesion protein interaction involved in synaptic maintenance and neurological disorders. Anal Biochem 2019; 587:113463. [PMID: 31574254 DOI: 10.1016/j.ab.2019.113463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 09/26/2019] [Accepted: 09/26/2019] [Indexed: 12/28/2022]
Abstract
Synaptic adhesion molecules, including presynaptic neurexins (NRXNs) and post-synaptic leucine-rich repeat transmembrane (LRRTM) proteins are important for development and maintenance of brain neuronal networks. NRXNs are probably the best characterized synaptic adhesion molecules, and one of the major presynaptic organizer proteins. The LRRTMs were found as ligands for NRXNs. Many of the synaptic adhesion proteins have been linked to neurological cognitive disorders, such as schizophrenia and autism spectrum disorders, making them targets of interest for both biological studies, and towards drug development. Therefore, we decided to develop a screening method to target the adhesion proteins, here the LRRTM-NRXN interaction, to find small molecule probes for further studies in cellular settings. To our knowledge, no potent small molecule compounds against the neuronal synaptic adhesion proteins are available. We utilized the AlphaScreen technology, and developed an assay targeting the NRXN-LRRTM2 interaction. We carried out screening of 2000 compounds and identified hits with moderate IC50-values. We also established an orthogonal in-cell Western blot assay to validate hits. This paves way for future development of specific high affinity compounds by further high throughput screening of larger compound libraries using the methods established here. The method could also be applied to screening other NRXN-ligand interactions.
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Affiliation(s)
- Sudeep Karki
- Institute of Biotechnology, University of Helsinki, Finland
| | - Mirko M Maksimainen
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu University of Oulu, Finland
| | - Lari Lehtiö
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu University of Oulu, Finland
| | - Tommi Kajander
- Institute of Biotechnology, University of Helsinki, Finland.
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22
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Emerging Roles of Synapse Organizers in the Regulation of Critical Periods. Neural Plast 2019; 2019:1538137. [PMID: 31565044 PMCID: PMC6745111 DOI: 10.1155/2019/1538137] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/09/2019] [Accepted: 07/25/2019] [Indexed: 01/10/2023] Open
Abstract
Experience remodels cortical connectivity during developmental windows called critical periods. Experience-dependent regulation of synaptic strength during these periods establishes circuit functions that are stabilized as critical period plasticity wanes. These processes have been extensively studied in the developing visual cortex, where critical period opening and closure are orchestrated by the assembly, maturation, and strengthening of distinct synapse types. The synaptic specificity of these processes points towards the involvement of distinct molecular pathways. Attractive candidates are pre- and postsynaptic transmembrane proteins that form adhesive complexes across the synaptic cleft. These synapse-organizing proteins control synapse development and maintenance and modulate structural and functional properties of synapses. Recent evidence suggests that they have pivotal roles in the onset and closure of the critical period for vision. In this review, we describe roles of synapse-organizing adhesion molecules in the regulation of visual critical period plasticity and we discuss the potential they offer to restore circuit functions in amblyopia and other neurodevelopmental disorders.
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23
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MicroRNA-186-5p controls GluA2 surface expression and synaptic scaling in hippocampal neurons. Proc Natl Acad Sci U S A 2019; 116:5727-5736. [PMID: 30808806 DOI: 10.1073/pnas.1900338116] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Homeostatic synaptic scaling is a negative feedback response to fluctuations in synaptic strength induced by developmental or learning-related processes, which maintains neuronal activity stable. Although several components of the synaptic scaling apparatus have been characterized, the intrinsic regulatory mechanisms promoting scaling remain largely unknown. MicroRNAs may contribute to posttranscriptional control of mRNAs implicated in different stages of synaptic scaling, but their role in these mechanisms is still undervalued. Here, we report that chronic blockade of glutamate receptors of the AMPA and NMDA types in hippocampal neurons in culture induces changes in the neuronal mRNA and miRNA transcriptomes, leading to synaptic upscaling. Specifically, we show that synaptic activity blockade persistently down-regulates miR-186-5p. Moreover, we describe a conserved miR-186-5p-binding site within the 3'UTR of the mRNA encoding the AMPA receptor GluA2 subunit, and demonstrate that GluA2 is a direct target of miR-186-5p. Overexpression of miR-186 decreased GluA2 surface levels, increased synaptic expression of GluA2-lacking AMPA receptors, and blocked synaptic scaling, whereas inhibition of miR-186-5p increased GluA2 surface levels and the amplitude and frequency of AMPA receptor-mediated currents, and mimicked excitatory synaptic scaling induced by synaptic inactivity. Our findings elucidate an activity-dependent miRNA-mediated mechanism for regulation of AMPA receptor expression.
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24
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Gorlewicz A, Kaczmarek L. Pathophysiology of Trans-Synaptic Adhesion Molecules: Implications for Epilepsy. Front Cell Dev Biol 2018; 6:119. [PMID: 30298130 PMCID: PMC6160742 DOI: 10.3389/fcell.2018.00119] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Accepted: 08/30/2018] [Indexed: 12/31/2022] Open
Abstract
Chemical synapses are specialized interfaces between neurons in the brain that transmit and modulate information, thereby integrating cells into multiplicity of interacting neural circuits. Cell adhesion molecules (CAMs) might form trans-synaptic complexes that are crucial for the appropriate identification of synaptic partners and further for the establishment, properties, and dynamics of synapses. When affected, trans-synaptic adhesion mechanisms play a role in synaptopathies in a variety of neuropsychiatric disorders including epilepsy. This review recapitulates current understanding of trans-synaptic interactions in pathophysiology of interneuronal connections. In particular, we discuss here the possible implications of trans-synaptic adhesion dysfunction for epilepsy.
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Affiliation(s)
- Adam Gorlewicz
- Laboratory of Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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25
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Dynamics, nanoscale organization, and function of synaptic adhesion molecules. Mol Cell Neurosci 2018; 91:95-107. [DOI: 10.1016/j.mcn.2018.04.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 04/12/2018] [Accepted: 04/13/2018] [Indexed: 12/13/2022] Open
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26
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Schroeder A, Vanderlinden J, Vints K, Ribeiro LF, Vennekens KM, Gounko NV, Wierda KD, de Wit J. A Modular Organization of LRR Protein-Mediated Synaptic Adhesion Defines Synapse Identity. Neuron 2018; 99:329-344.e7. [PMID: 29983322 DOI: 10.1016/j.neuron.2018.06.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 05/04/2018] [Accepted: 06/14/2018] [Indexed: 10/28/2022]
Abstract
Pyramidal neurons express rich repertoires of leucine-rich repeat (LRR)-containing adhesion molecules with similar synaptogenic activity in culture. The in vivo relevance of this molecular diversity is unclear. We show that hippocampal CA1 pyramidal neurons express multiple synaptogenic LRR proteins that differentially distribute to the major excitatory inputs on their apical dendrites. At Schaffer collateral (SC) inputs, FLRT2, LRRTM1, and Slitrk1 are postsynaptically localized and differentially regulate synaptic structure and function. FLRT2 controls spine density, whereas LRRTM1 and Slitrk1 exert opposing effects on synaptic vesicle distribution at the active zone. All LRR proteins differentially affect synaptic transmission, and their combinatorial loss results in a cumulative phenotype. At temporoammonic (TA) inputs, LRRTM1 is absent; FLRT2 similarly controls functional synapse number, whereas Slitrk1 function diverges to regulate postsynaptic AMPA receptor density. Thus, LRR proteins differentially control synaptic architecture and function and act in input-specific combinations and a context-dependent manner to specify synaptic properties.
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Affiliation(s)
- Anna Schroeder
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Jeroen Vanderlinden
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Katlijn Vints
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium; Electron Microscopy Platform & VIB BioImaging Core, Herestraat 49, 3000 Leuven, Belgium
| | - Luís F Ribeiro
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Kristel M Vennekens
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Natalia V Gounko
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium; Electron Microscopy Platform & VIB BioImaging Core, Herestraat 49, 3000 Leuven, Belgium
| | - Keimpe D Wierda
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium.
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27
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PTPσ Drives Excitatory Presynaptic Assembly via Various Extracellular and Intracellular Mechanisms. J Neurosci 2018; 38:6700-6721. [PMID: 29934346 DOI: 10.1523/jneurosci.0672-18.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/22/2018] [Accepted: 06/14/2018] [Indexed: 11/21/2022] Open
Abstract
Leukocyte common antigen-receptor protein tyrosine phosphatases (LAR-RPTPs) are hub proteins that organize excitatory and inhibitory synapse development through binding to various extracellular ligands. Here, we report that knockdown (KD) of the LAR-RPTP family member PTPσ reduced excitatory synapse number and transmission in cultured rat hippocampal neurons, whereas KD of PTPδ produced comparable decreases at inhibitory synapses, in both cases without altering expression levels of interacting proteins. An extensive series of rescue experiments revealed that extracellular interactions of PTPσ with Slitrks are important for excitatory synapse development. These experiments further showed that the intracellular D2 domain of PTPσ is required for induction of heterologous synapse formation by Slitrk1 or TrkC, suggesting that interaction of LAR-RPTPs with distinct intracellular presynaptic proteins, drives presynaptic machinery assembly. Consistent with this, double-KD of liprin-α2 and -α3 or KD of PTPσ substrates (N-cadherin and p250RhoGAP) in neurons inhibited Slitrk6-induced, PTPσ-mediated heterologous synapse formation activity. We propose a synaptogenesis model in presynaptic neurons involving LAR-RPTP-organized retrograde signaling cascades, in which both extracellular and intracellular mechanisms are critical in orchestrating distinct synapse types.SIGNIFICANCE STATEMENT In this study, we sought to test the unproven hypothesis that PTPσ and PTPδ are required for excitatory and inhibitory synapse formation/transmission, respectively, in cultured hippocampal neurons, using knockdown-based loss-of-function analyses. We further performed extensive structure-function analyses, focusing on PTPσ-mediated actions, to address the mechanisms of presynaptic assembly at excitatory synaptic sites. Using interdisciplinary approaches, we systematically applied a varied set of PTPσ deletion variants, point mutants, and splice variants to demonstrate that both extracellular and intracellular mechanisms are involved in organizing presynaptic assembly. Strikingly, extracellular interactions of PTPσ with heparan sulfates and Slitrks, intracellular interactions of PTPσ with liprin-α and its associated proteins through the D2 domain, as well as distinct substrates are all critical.
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28
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Deletion of LRRTM1 and LRRTM2 in adult mice impairs basal AMPA receptor transmission and LTP in hippocampal CA1 pyramidal neurons. Proc Natl Acad Sci U S A 2018; 115:E5382-E5389. [PMID: 29784826 DOI: 10.1073/pnas.1803280115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Leucine-rich repeat transmembrane (LRRTM) proteins are synaptic cell adhesion molecules that influence synapse formation and function. They are genetically associated with neuropsychiatric disorders, and via their synaptic actions likely regulate the establishment and function of neural circuits in the mammalian brain. Here, we take advantage of the generation of a LRRTM1 and LRRTM2 double conditional knockout mouse (LRRTM1,2 cKO) to examine the role of LRRTM1,2 at mature excitatory synapses in hippocampal CA1 pyramidal neurons. Genetic deletion of LRRTM1,2 in vivo in CA1 neurons using Cre recombinase-expressing lentiviruses dramatically impaired long-term potentiation (LTP), an impairment that was rescued by simultaneous expression of LRRTM2, but not LRRTM4. Mutation or deletion of the intracellular tail of LRRTM2 did not affect its ability to rescue LTP, while point mutations designed to impair its binding to presynaptic neurexins prevented rescue of LTP. In contrast to previous work using shRNA-mediated knockdown of LRRTM1,2, KO of these proteins at mature synapses also caused a decrease in AMPA receptor-mediated, but not NMDA receptor-mediated, synaptic transmission and had no detectable effect on presynaptic function. Imaging of recombinant photoactivatable AMPA receptor subunit GluA1 in the dendritic spines of cultured neurons revealed that it was less stable in the absence of LRRTM1,2. These results illustrate the advantages of conditional genetic deletion experiments for elucidating the function of endogenous synaptic proteins and suggest that LRRTM1,2 proteins help stabilize synaptic AMPA receptors at mature spines during basal synaptic transmission and LTP.
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29
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Constance WD, Mukherjee A, Fisher YE, Pop S, Blanc E, Toyama Y, Williams DW. Neurexin and Neuroligin-based adhesion complexes drive axonal arborisation growth independent of synaptic activity. eLife 2018; 7:31659. [PMID: 29504935 PMCID: PMC5869020 DOI: 10.7554/elife.31659] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 03/04/2018] [Indexed: 11/25/2022] Open
Abstract
Building arborisations of the right size and shape is fundamental for neural network function. Live imaging in vertebrate brains strongly suggests that nascent synapses are critical for branch growth during development. The molecular mechanisms underlying this are largely unknown. Here we present a novel system in Drosophila for studying the development of complex arborisations live, in vivo during metamorphosis. In growing arborisations we see branch dynamics and localisations of presynaptic proteins very similar to the ‘synaptotropic growth’ described in fish/frogs. These accumulations of presynaptic proteins do not appear to be presynaptic release sites and are not paired with neurotransmitter receptors. Knockdowns of either evoked or spontaneous neurotransmission do not impact arbor growth. Instead, we find that axonal branch growth is regulated by dynamic, focal localisations of Neurexin and Neuroligin. These adhesion complexes provide stability for filopodia by a ‘stick-and-grow’ based mechanism wholly independent of synaptic activity.
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Affiliation(s)
- William D Constance
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom.,King's-NUS Joint Studentship Program, King's College London, London, United Kingdom
| | - Amrita Mukherjee
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Yvette E Fisher
- Department of Neurobiology, Stanford University, Stanford, United States.,Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Sinziana Pop
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Eric Blanc
- Berlin Institute of Health, Berlin, Germany
| | - Yusuke Toyama
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore.,Temasek Life Sciences Laboratory, Singapore, Singapore.,Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Darren W Williams
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
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30
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Monavarfeshani A, Stanton G, Van Name J, Su K, Mills WA, Swilling K, Kerr A, Huebschman NA, Su J, Fox MA. LRRTM1 underlies synaptic convergence in visual thalamus. eLife 2018; 7:e33498. [PMID: 29424692 PMCID: PMC5826289 DOI: 10.7554/elife.33498] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 02/08/2018] [Indexed: 11/13/2022] Open
Abstract
It has long been thought that the mammalian visual system is organized into parallel pathways, with incoming visual signals being parsed in the retina based on feature (e.g. color, contrast and motion) and then transmitted to the brain in unmixed, feature-specific channels. To faithfully convey feature-specific information from retina to cortex, thalamic relay cells must receive inputs from only a small number of functionally similar retinal ganglion cells. However, recent studies challenged this by revealing substantial levels of retinal convergence onto relay cells. Here, we sought to identify mechanisms responsible for the assembly of such convergence. Using an unbiased transcriptomics approach and targeted mutant mice, we discovered a critical role for the synaptic adhesion molecule Leucine Rich Repeat Transmembrane Neuronal 1 (LRRTM1) in the emergence of retinothalamic convergence. Importantly, LRRTM1 mutant mice display impairment in visual behaviors, suggesting a functional role of retinothalamic convergence in vision.
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Affiliation(s)
- Aboozar Monavarfeshani
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
- Department of Biological SciencesVirginia TechBlacksburgUnited States
| | - Gail Stanton
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
- Virginia Tech Carilion School of MedicineRoanokeUnited States
| | - Jonathan Van Name
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
| | - Kaiwen Su
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
| | - William A Mills
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
- Translational Biology, Medicine, and Health Graduate ProgramVirginia TechBlacksburgUnited States
| | - Kenya Swilling
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
| | - Alicia Kerr
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
- Translational Biology, Medicine, and Health Graduate ProgramVirginia TechBlacksburgUnited States
| | | | - Jianmin Su
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
| | - Michael A Fox
- Developmental and Translational Neurobiology CenterVirginia Tech Carilion Research InstituteRoanokeUnited States
- Department of Biological SciencesVirginia TechBlacksburgUnited States
- Virginia Tech Carilion School of MedicineRoanokeUnited States
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31
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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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32
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Identification of Protein Tyrosine Phosphatase Receptor Type O (PTPRO) as a Synaptic Adhesion Molecule that Promotes Synapse Formation. J Neurosci 2017; 37:9828-9843. [PMID: 28871037 DOI: 10.1523/jneurosci.0729-17.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/26/2017] [Accepted: 08/22/2017] [Indexed: 01/07/2023] Open
Abstract
The proper formation of synapses-specialized unitary structures formed between two neurons-is critical to mediating information flow in the brain. Synaptic cell adhesion molecules (CAMs) are thought to participate in the initiation of the synapse formation process. However, in vivo functional analysis demonstrates that most well known synaptic CAMs regulate synaptic maturation and plasticity rather than synapse formation, suggesting that either CAMs work synergistically in the process of forming synapses or more CAMs remain to be found. By screening for unknown CAMs using a co-culture system, we revealed that protein tyrosine phosphatase receptor type O (PTPRO) is a potent CAM that induces the formation of artificial synapse clusters in co-cultures of human embryonic kidney 293 cells and hippocampal neurons cultured from newborn mice regardless of gender. PTPRO was enriched in the mouse brain and localized to postsynaptic sites at excitatory synapses. The overexpression of PTPRO in cultured hippocampal neurons increased the number of synapses and the frequency of miniature EPSCs (mEPSCs). The knock-down (KD) of PTPRO expression in cultured neurons by short hairpin RNA (shRNA) reduced the number of synapses and the frequencies of the mEPSCs. The effects of shRNA KD were rescued by expressing either full-length PTPRO or a truncated PTPRO lacking the cytoplasmic domain. Consistent with these results, the N-terminal extracellular domain of PTPRO was required for its synaptogenic activity in the co-culture assay. Our data show that PTPRO is a synaptic CAM that serves as a potent initiator of the formation of excitatory synapses.SIGNIFICANCE STATEMENT The formation of synapses is critical for the brain to execute its function and synaptic cell adhesion molecules (CAMs) play essential roles in initiating the formation of synapses. By screening for unknown CAMs using a co-culture system, we revealed that protein tyrosine phosphatase receptor type O (PTPRO) is a potent CAM that induces the formation of artificial synapse clusters. Using loss-of-function and gain-of-function approaches, we show that PTPRO promotes the formation of excitatory synapses. The N-terminal extracellular domain of PTPRO was required for its synaptogenic activity in cultured hippocampal neurons and the co-culture assay. Together, our data show that PTPRO is a synaptic CAM that serves as a potent initiator of synapse formation.
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33
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Neurotrophin-3 Regulates Synapse Development by Modulating TrkC-PTPσ Synaptic Adhesion and Intracellular Signaling Pathways. J Neurosci 2017; 36:4816-31. [PMID: 27122038 DOI: 10.1523/jneurosci.4024-15.2016] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 03/20/2016] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Neurotrophin-3 (NT-3) is a secreted neurotrophic factor that binds neurotrophin receptor tyrosine kinase C (TrkC), which in turn binds to presynaptic protein tyrosine phosphatase σ (PTPσ) to govern excitatory synapse development. However, whether and how NT-3 cooperates with the TrkC-PTPσ synaptic adhesion pathway and TrkC-mediated intracellular signaling pathways in rat cultured neurons has remained unclear. Here, we report that NT-3 enhances TrkC binding affinity for PTPσ. Strikingly, NT-3 treatment bidirectionally regulates the synaptogenic activity of TrkC: at concentrations of 10-25 ng/ml, NT-3 further enhanced the increase in synapse density induced by TrkC overexpression, whereas at higher concentrations, NT-3 abrogated TrkC-induced increases in synapse density. Semiquantitative immunoblotting and optogenetics-based imaging showed that 25 ng/ml NT-3 or light stimulation at a power that produced a comparable level of NT-3 (6.25 μW) activated only extracellular signal-regulated kinase (ERK) and Akt, whereas 100 ng/ml NT-3 (light intensity, 25 μW) further triggered the activation of phospholipase C-γ1 and CREB independently of PTPσ. Notably, disruption of TrkC intracellular signaling pathways, extracellular ligand binding, or kinase activity by point mutations compromised TrkC-induced increases in synapse density. Furthermore, only sparse, but not global, TrkC knock-down in cultured rat neurons significantly decreased synapse density, suggesting that intercellular differences in TrkC expression level are critical for its synapse-promoting action. Together, our data demonstrate that NT-3 is a key factor in excitatory synapse development that may direct higher-order assembly of the TrkC/PTPσ complex and activate distinct intracellular signaling cascades in a concentration-dependent manner to promote competition-based synapse development processes. SIGNIFICANCE STATEMENT In this study, we present several lines of experimental evidences to support the conclusion that neurotrophin-3 (NT-3) modulates the synaptic adhesion pathway involving neurotrophin receptor tyrosine kinase C (TrkC) and presynaptic protein tyrosine phosphatase σ (PTPσ) in a bidirectional manner at excitatory synapses. NT-3 acts in concentration-independent manner to facilitate TrkC-mediated presynaptic differentiation, whereas it acts in a concentration-dependent manner to exert differential effects on TrkC-mediated organization of postsynaptic development. We further investigated TrkC extracellular ligand binding, intracellular signaling pathways, and kinase activity in NT-3-induced synapse development. Last, we found that interneuronal differences in TrkC levels regulate the synapse number. Overall, these results suggest that NT-3 functions as a positive modulator of synaptogenesis involving TrkC and PTPσ.
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Unique versus Redundant Functions of Neuroligin Genes in Shaping Excitatory and Inhibitory Synapse Properties. J Neurosci 2017; 37:6816-6836. [PMID: 28607166 DOI: 10.1523/jneurosci.0125-17.2017] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 05/10/2017] [Accepted: 05/31/2017] [Indexed: 11/21/2022] Open
Abstract
Neuroligins are evolutionarily conserved postsynaptic cell adhesion molecules that interact with presynaptic neurexins. Neurons express multiple neuroligin isoforms that are targeted to specific synapses, but their synaptic functions and mechanistic redundancy are not completely understood. Overexpression or RNAi-mediated knockdown of neuroligins, respectively, causes a dramatic increase or decrease in synapse density, whereas genetic deletions of neuroligins impair synapse function with only minor effects on synapse numbers, raising fundamental questions about the overall physiological role of neuroligins. Here, we have systematically analyzed the effects of conditional genetic deletions of all major neuroligin isoforms (i.e., NL1, NL2, and NL3), either individually or in combinations, in cultured mouse hippocampal and cortical neurons. We found that conditional genetic deletions of neuroligins caused no change or only a small change in synapses numbers, but strongly impaired synapse function. This impairment was isoform specific, suggesting that neuroligins are not functionally redundant. Sparse neuroligin deletions produced phenotypes comparable to those of global deletions, indicating that neuroligins function in a cell-autonomous manner. Mechanistically, neuroligin deletions decreased the synaptic levels of neurotransmitter receptors and had no effect on presynaptic release probabilities. Overexpression of neuroligin-1 in control or neuroligin-deficient neurons increased synaptic transmission and synapse density but not spine numbers, suggesting that these effects reflect a gain-of-function mechanism; whereas overexpression of neuroligin-3, which, like neuroligin-1 is also targeted to excitatory synapses, had no comparable effect. Our data demonstrate that neuroligins are required for the physiological organization of neurotransmitter receptors in postsynaptic specializations and suggest that they do not play a major role in synapse formation.SIGNIFICANCE STATEMENT Human neuroligin genes have been associated with autism, but the cellular functions of different neuroligins and their molecular mechanisms remain incompletely understood. Here, we performed comparative analyses in cultured mouse neurons of all major neuroligin isoforms, either individually or in combinations, using conditional knockouts. We found that neuroligin deletions did not affect synapse numbers but differentially impaired excitatory or inhibitory synaptic functions in an isoform-specific manner. These impairments were due, at least in part, to a decrease in synaptic distribution of neurotransmitter receptors upon deletion of neuroligins. Conversely, the overexpression of neuroligin-1 increased synapse numbers but not spine numbers. Our results suggest that various neuroligin isoforms perform unique postsynaptic functions in organizing synapses but are not essential for synapse formation or maintenance.
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Pan-neurexin perturbation results in compromised synapse stability and a reduction in readily releasable synaptic vesicle pool size. Sci Rep 2017; 7:42920. [PMID: 28220838 PMCID: PMC5318902 DOI: 10.1038/srep42920] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/16/2017] [Indexed: 11/08/2022] Open
Abstract
Neurexins are a diverse family of cell adhesion molecules that localize to presynaptic specializations of CNS neurons. Heterologous expression of neurexins in non-neuronal cells leads to the recruitment of postsynaptic proteins in contacting dendrites of co-cultured neurons, implicating neurexins in synapse formation. However, isoform-specific knockouts of either all α- or all β-neurexins show defects in synaptic transmission but an unaltered density of glutamatergic synapses, a finding that argues against an essential function of neurexins in synaptogenesis. To address the role of neurexin in synapse formation and function, we disrupted the function of all α- and β-neurexins in cultured hippocampal neurons by shRNA knockdown or by overexpressing a neurexin mutant that is unable to bind to postsynaptic neurexin ligands. We show that neurexin perturbation results in an attenuation of neurotransmitter release that is in large part due to a reduction in the number of readily releasable synaptic vesicles. We also find that neurexin perturbation fails to alter the ability of neurons to form synapses, but rather leads to more frequent synapse elimination. These experiments suggest that neurexins are dispensable for the formation of initial synaptic contacts, but play an essential role in the stabilization and functional maturation of synapses.
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Dynamic Control of Synaptic Adhesion and Organizing Molecules in Synaptic Plasticity. Neural Plast 2017; 2017:6526151. [PMID: 28255461 PMCID: PMC5307005 DOI: 10.1155/2017/6526151] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 12/13/2016] [Indexed: 12/13/2022] Open
Abstract
Synapses play a critical role in establishing and maintaining neural circuits, permitting targeted information transfer throughout the brain. A large portfolio of synaptic adhesion/organizing molecules (SAMs) exists in the mammalian brain involved in synapse development and maintenance. SAMs bind protein partners, forming trans-complexes spanning the synaptic cleft or cis-complexes attached to the same synaptic membrane. SAMs play key roles in cell adhesion and in organizing protein interaction networks; they can also provide mechanisms of recognition, generate scaffolds onto which partners can dock, and likely take part in signaling processes as well. SAMs are regulated through a portfolio of different mechanisms that affect their protein levels, precise localization, stability, and the availability of their partners at synapses. Interaction of SAMs with their partners can further be strengthened or weakened through alternative splicing, competing protein partners, ectodomain shedding, or astrocytically secreted factors. Given that numerous SAMs appear altered by synaptic activity, in vivo, these molecules may be used to dynamically scale up or scale down synaptic communication. Many SAMs, including neurexins, neuroligins, cadherins, and contactins, are now implicated in neuropsychiatric and neurodevelopmental diseases, such as autism spectrum disorder, schizophrenia, and bipolar disorder and studying their molecular mechanisms holds promise for developing novel therapeutics.
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Roppongi RT, Karimi B, Siddiqui TJ. Role of LRRTMs in synapse development and plasticity. Neurosci Res 2016; 116:18-28. [PMID: 27810425 DOI: 10.1016/j.neures.2016.10.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 10/10/2016] [Accepted: 10/14/2016] [Indexed: 12/19/2022]
Abstract
Leucine-rich-repeat transmembrane neuronal proteins (LRRTMs) are a family of four synapse organizing proteins critical for the development and function of excitatory synapses. The genes encoding LRRTMs and their binding partners, neurexins and HSPGs, are strongly associated with multiple psychiatric disorders. Here, we review the literature covering their structural features, expression patterns in the developing and adult brains, evolutionary origins, and discovery as synaptogenic proteins. We also discuss their role in the development and plasticity of excitatory synapses as well as their disease associations.
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Affiliation(s)
- Reiko T Roppongi
- Department of Physiology and Pathophysiology, College of Medicine, University of Manitoba, Winnipeg, MB, Canada; Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, 710 William Avenue, Winnipeg R3Y 0Z3, MB, Canada
| | - Benyamin Karimi
- Department of Physiology and Pathophysiology, College of Medicine, University of Manitoba, Winnipeg, MB, Canada; Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, 710 William Avenue, Winnipeg R3Y 0Z3, MB, Canada
| | - Tabrez J Siddiqui
- Department of Physiology and Pathophysiology, College of Medicine, University of Manitoba, Winnipeg, MB, Canada; Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, 710 William Avenue, Winnipeg R3Y 0Z3, MB, Canada.
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Kang H, Han KA, Won SY, Kim HM, Lee YH, Ko J, Um JW. Slitrk Missense Mutations Associated with Neuropsychiatric Disorders Distinctively Impair Slitrk Trafficking and Synapse Formation. Front Mol Neurosci 2016; 9:104. [PMID: 27812321 PMCID: PMC5071332 DOI: 10.3389/fnmol.2016.00104] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 10/04/2016] [Indexed: 12/29/2022] Open
Abstract
Slit- and Trk-like (Slitrks) are a six-member family of synapse organizers that control excitatory and inhibitory synapse formation by forming trans-synaptic adhesions with LAR receptor protein tyrosine phosphatases (PTPs). Intriguingly, genetic mutations of Slitrks have been associated with a multitude of neuropsychiatric disorders. However, nothing is known about the neuronal and synaptic consequences of these mutations. Here, we report the structural and functional effects on synapses of various rare de novo mutations identified in patients with schizophrenia or Tourette syndrome. A number of single amino acid substitutions in Slitrk1 (N400I or T418S) or Slitrk4 (V206I or I578V) reduced their surface expression levels. These substitutions impaired glycosylation of Slitrks expressed in HEK293T cells, caused retention of Slitrks in the endoplasmic reticulum and cis-Golgi compartment in COS-7 cells and neurons, and abolished Slitrk binding to PTPδ. Furthermore, these substitutions eliminated the synapse-inducing activity of Slitrks, abolishing their functional effects on synapse density in cultured neurons. Strikingly, a valine-to-methionine mutation in Slitrk2 (V89M) compromised synapse formation activity in cultured neuron, without affecting surface transport, expression, or synapse-inducing activity in coculture assays. Similar deleterious effects were observed upon introduction of the corresponding valine-to-methionine mutation into Slitrk1 (V85M), suggesting that this conserved valine residue plays a key role in maintaining the synaptic functions of Slitrks. Collectively, these data indicate that inactivation of distinct cellular mechanisms caused by specific Slitrk dysfunctions may underlie Slitrk-associated neuropsychiatric disorders in humans, and provide a robust cellular readout for the development of knowledge-based therapies.
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Affiliation(s)
- Hyeyeon Kang
- Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine Seoul, Korea
| | - Kyung Ah Han
- Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine Seoul, Korea
| | - Seoung Youn Won
- Department of Chemistry, Korea Advanced Institute of Science and Technology Daejeon, Korea
| | - Ho Min Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology Daejeon, Korea
| | - Young-Ho Lee
- Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine Seoul, Korea
| | - Jaewon Ko
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University Seoul, Korea
| | - Ji Won Um
- Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine Seoul, Korea
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Baig DN, Yanagawa T, Tabuchi K. Distortion of the normal function of synaptic cell adhesion molecules by genetic variants as a risk for autism spectrum disorders. Brain Res Bull 2016; 129:82-90. [PMID: 27743928 DOI: 10.1016/j.brainresbull.2016.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 10/08/2016] [Accepted: 10/10/2016] [Indexed: 12/15/2022]
Abstract
Synaptic cell adhesion molecules (SCAMs) are a functional category of cell adhesion molecules that connect pre- and postsynapses by the protein-protein interaction via their extracellular cell adhesion domains. Countless numbers of common genetic variants and rare mutations in SCAMs have been identified in the patients with autism spectrum disorders (ASDs). Among these, NRXN and NLGN family proteins cooperatively function at synaptic terminals both of which genes are strongly implicated as risk genes for ASDs. Knock-in mice carrying a single rare point mutation of NLGN3 (NLGN3 R451C) discovered in the patients with ASDs display a deficit in social interaction and an enhancement of spatial learning and memory ability reminiscent of the clinical phenotype of ASDs. NLGN4 knockout (KO) and NRXN2α KO mice also show a deficit in sociability as well as some specific neuropsychiatric behaviors. In this review, we selected NRXNs/NLGNs, CNTNAP2/CNTNAP4, CNTN4, ITGB3, and KIRREL3 as strong ASD risk genes based on SFARI score and summarize the protein structures, functions at synapses, representative discoveries in human genetic studies, and phenotypes of the mutant model mice in light of the pathophysiology of ASDs.
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Affiliation(s)
- Deeba Noreen Baig
- Department of Biological Sciences, Forman Christian College, Zahoor Elahi Rd, Lahore, 54600, Pakistan
| | - Toru Yanagawa
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, University of Tsukuba, Ibaraki, 305-8575, Japan
| | - Katsuhiko Tabuchi
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan; Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto, 390-8621, Japan; PRESTO, JST, Saitama, 332-0012, Japan.
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SALM4 suppresses excitatory synapse development by cis-inhibiting trans-synaptic SALM3-LAR adhesion. Nat Commun 2016; 7:12328. [PMID: 27480238 PMCID: PMC4974644 DOI: 10.1038/ncomms12328] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 06/23/2016] [Indexed: 12/01/2022] Open
Abstract
Synaptic adhesion molecules regulate various aspects of synapse development, function and plasticity. These functions mainly involve trans-synaptic interactions and positive regulations, whereas cis-interactions and negative regulation are less understood. Here we report that SALM4, a member of the SALM/Lrfn family of synaptic adhesion molecules, suppresses excitatory synapse development through cis inhibition of SALM3, another SALM family protein with synaptogenic activity. Salm4-mutant (Salm4−/−) mice show increased excitatory synapse numbers in the hippocampus. SALM4 cis-interacts with SALM3, inhibits trans-synaptic SALM3 interaction with presynaptic LAR family receptor tyrosine phosphatases and suppresses SALM3-dependent presynaptic differentiation. Importantly, deletion of Salm3 in Salm4−/− mice (Salm3−/−; Salm4−/−) normalizes the increased excitatory synapse number. These results suggest that SALM4 negatively regulates excitatory synapses via cis inhibition of the trans-synaptic SALM3–LAR adhesion. Synaptic adhesion molecules regulate synapse development and function by both cis and trans-interactions. Here, Lie et al. show that postsynaptic SALM4 regulates excitatory synapse numbers by cis inhibition of the SALM3-LAR transynaptic interaction.
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Choi Y, Nam J, Whitcomb DJ, Song YS, Kim D, Jeon S, Um JW, Lee SG, Woo J, Kwon SK, Li Y, Mah W, Kim HM, Ko J, Cho K, Kim E. SALM5 trans-synaptically interacts with LAR-RPTPs in a splicing-dependent manner to regulate synapse development. Sci Rep 2016; 6:26676. [PMID: 27225731 PMCID: PMC4881023 DOI: 10.1038/srep26676] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 05/04/2016] [Indexed: 11/08/2022] Open
Abstract
Synaptogenic adhesion molecules play critical roles in synapse formation. SALM5/Lrfn5, a SALM/Lrfn family adhesion molecule implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons, but its presynaptic ligand remains unknown. We found that SALM5 interacts with the Ig domains of LAR family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPδ, and PTPσ). These interactions are strongly inhibited by the splice insert B in the Ig domain region of LAR-RPTPs, and mediate SALM5-dependent presynaptic differentiation in contacting axons. In addition, SALM5 regulates AMPA receptor-mediated synaptic transmission through mechanisms involving the interaction of postsynaptic SALM5 with presynaptic LAR-RPTPs. These results suggest that postsynaptic SALM5 promotes synapse development by trans-synaptically interacting with presynaptic LAR-RPTPs and is important for the regulation of excitatory synaptic strength.
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Affiliation(s)
- Yeonsoo Choi
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Jungyong Nam
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Daniel J. Whitcomb
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, United Kingdom
| | - Yoo Sung Song
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Gyeonggi-do, 463–707, Korea
| | - Doyoun Kim
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
| | - Sangmin Jeon
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Ji Won Um
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
- Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Seong-Gyu Lee
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Jooyeon Woo
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Seok-Kyu Kwon
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Yan Li
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
| | - Won Mah
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Ho Min Kim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 305-701, Korea
| | - Jaewon Ko
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Kwangwook Cho
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, United Kingdom
- Centre for Synaptic Plasticity, University of Bristol, Bristol BS1 3NY, United Kingdom
| | - Eunjoon Kim
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
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Um JW, Choii G, Park D, Kim D, Jeon S, Kang H, Mori T, Papadopoulos T, Yoo T, Lee Y, Kim E, Tabuchi K, Ko J. IQ Motif and SEC7 Domain-containing Protein 3 (IQSEC3) Interacts with Gephyrin to Promote Inhibitory Synapse Formation. J Biol Chem 2016; 291:10119-30. [PMID: 27002143 DOI: 10.1074/jbc.m115.712893] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Indexed: 01/13/2023] Open
Abstract
Gephyrin is a central scaffold protein that mediates development, function, and plasticity of mammalian inhibitory synapses by interacting with various inhibitory synaptic proteins. Here, we show that IQSEC3, a guanine nucleotide exchange factor for ARF6, directly interacts with gephyrin, an interaction that is critical for the inhibitory synapse localization of IQSEC3. Overexpression of IQSEC3 increases inhibitory, but not excitatory, synapse density in a guanine nucleotide exchange factor activity-dependent manner. Conversely, knockdown of IQSEC3 decreases size of gephyrin cluster without altering gephyrin puncta density. Collectively, these data reveal that IQSEC3 acts together with gephyrin to regulate inhibitory synapse development.
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Affiliation(s)
- Ji Won Um
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea, the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Gayoung Choii
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Dongseok Park
- the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Dongwook Kim
- the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Sangmin Jeon
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Hyeyeon Kang
- the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Takuma Mori
- the Shinshu University School of Medicine, Matsumoto 390-8621, Japan
| | - Theofilos Papadopoulos
- the Department of Molecular Biology, University Medicine Göttingen, Göttingen 37075, Germany
| | - Taesun Yoo
- the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Yeunkum Lee
- the Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 305-701, Republic of Korea, and
| | - Eunjoon Kim
- the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea, the Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 305-701, Republic of Korea, and
| | - Katsuhiko Tabuchi
- the Shinshu University School of Medicine, Matsumoto 390-8621, Japan, PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Jaewon Ko
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea,
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Mapping the dynamics and nanoscale organization of synaptic adhesion proteins using monomeric streptavidin. Nat Commun 2016; 7:10773. [PMID: 26979420 PMCID: PMC4799371 DOI: 10.1038/ncomms10773] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/17/2016] [Indexed: 12/12/2022] Open
Abstract
The advent of super-resolution imaging (SRI) has created a need for optimized labelling strategies. We present a new method relying on fluorophore-conjugated monomeric streptavidin (mSA) to label membrane proteins carrying a short, enzymatically biotinylated tag, compatible with SRI techniques including uPAINT, STED and dSTORM. We demonstrate efficient and specific labelling of target proteins in confined intercellular and organotypic tissues, with reduced steric hindrance and no crosslinking compared with multivalent probes. We use mSA to decipher the dynamics and nanoscale organization of the synaptic adhesion molecules neurexin-1β, neuroligin-1 (Nlg1) and leucine-rich-repeat transmembrane protein 2 (LRRTM2) in a dual-colour configuration with GFP nanobody, and show that these proteins are diffusionally trapped at synapses where they form apposed trans-synaptic adhesive structures. Furthermore, Nlg1 is dynamic, disperse and sensitive to synaptic stimulation, whereas LRRTM2 is organized in compact and stable nanodomains. Thus, mSA is a versatile tool to image membrane proteins at high resolution in complex live environments, providing novel information about the nano-organization of biological structures. The advent of fluorescence-based super-resolution microscopy has created a need for labeling strategies relying on small probes that minimally perturb protein function. Here the authors describe a labeling method that reduces protein tag and label sizes, allowing for accurate protein targeting and measurements of protein dynamics in tight cellular spaces.
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Um JW, Choi TY, Kang H, Cho YS, Choii G, Uvarov P, Park D, Jeong D, Jeon S, Lee D, Kim H, Lee SH, Bae YC, Choi SY, Airaksinen MS, Ko J. LRRTM3 Regulates Excitatory Synapse Development through Alternative Splicing and Neurexin Binding. Cell Rep 2016; 14:808-822. [PMID: 26776509 DOI: 10.1016/j.celrep.2015.12.081] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/29/2015] [Accepted: 12/16/2015] [Indexed: 11/27/2022] Open
Abstract
The four members of the LRRTM family (LRRTM1-4) are postsynaptic adhesion molecules essential for excitatory synapse development. They have also been implicated in neuropsychiatric diseases. Here, we focus on LRRTM3, showing that two distinct LRRTM3 variants generated by alternative splicing regulate LRRTM3 interaction with PSD-95, but not its excitatory synapse-promoting activity. Overexpression of either LRRTM3 variant increased excitatory synapse density in dentate gyrus (DG) granule neurons, whereas LRRTM3 knockdown decreased it. LRRTM3 also controlled activity-regulated AMPA receptor surface expression in an alternative splicing-dependent manner. Furthermore, Lrrtm3-knockout mice displayed specific alterations in excitatory synapse density, excitatory synaptic transmission and excitability in DG granule neurons but not in CA1 pyramidal neurons. Lastly, LRRTM3 required only specific splice variants of presynaptic neurexins for their synaptogenic activity. Collectively, our data highlight alternative splicing and differential presynaptic ligand utilization in the regulation of LRRTMs, revealing key regulatory mechanisms for excitatory synapse development.
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Affiliation(s)
- Ji Won Um
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea; Department of Physiology and BK21 PLUS Project to Medical Sciences, Yonsei University College of Medicine, Seoul 120-751, Korea
| | - Tae-Yong Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul 110-749, Korea
| | - Hyeyeon Kang
- Department of Physiology and BK21 PLUS Project to Medical Sciences, Yonsei University College of Medicine, Seoul 120-751, Korea
| | - Yi Sul Cho
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea
| | - Gayoung Choii
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Pavel Uvarov
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki 14, Finland
| | - Dongseok Park
- Department of Physiology and BK21 PLUS Project to Medical Sciences, Yonsei University College of Medicine, Seoul 120-751, Korea
| | - Daun Jeong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Sangmin Jeon
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Dongmin Lee
- Department of Anatomy and Neuroscience, Korea 21 Biomedical Science, College of Medicine, Korea University, 126-1, 5-ka, Anam-dong, Seongbuk-gu, Seoul 136-705, Korea
| | - Hyun Kim
- Department of Anatomy and Neuroscience, Korea 21 Biomedical Science, College of Medicine, Korea University, 126-1, 5-ka, Anam-dong, Seongbuk-gu, Seoul 136-705, Korea
| | - Seung-Hee Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Yong-Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea
| | - Se-Young Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul 110-749, Korea
| | - Matti S Airaksinen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki 14, Finland
| | - Jaewon Ko
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
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45
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Fedder KN, Sabo SL. On the Role of Glutamate in Presynaptic Development: Possible Contributions of Presynaptic NMDA Receptors. Biomolecules 2015; 5:3448-66. [PMID: 26694480 PMCID: PMC4693286 DOI: 10.3390/biom5043448] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 10/22/2015] [Accepted: 11/26/2015] [Indexed: 12/23/2022] Open
Abstract
Proper formation and maturation of synapses during development is a crucial step in building the functional neural circuits that underlie perception and behavior. It is well established that experience modifies circuit development. Therefore, understanding how synapse formation is controlled by synaptic activity is a key question in neuroscience. In this review, we focus on the regulation of excitatory presynaptic terminal development by glutamate, the predominant excitatory neurotransmitter in the brain. We discuss the evidence that NMDA receptor activation mediates these effects of glutamate and present the hypothesis that local activation of presynaptic NMDA receptors (preNMDARs) contributes to glutamate-dependent control of presynaptic development. Abnormal glutamate signaling and aberrant synapse development are both thought to contribute to the pathogenesis of a variety of neurodevelopmental disorders, including autism spectrum disorders, intellectual disability, epilepsy, anxiety, depression, and schizophrenia. Therefore, understanding how glutamate signaling and synapse development are linked is important for understanding the etiology of these diseases.
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Affiliation(s)
- Karlie N Fedder
- Departments of Pharmacology and Neuroscience, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
| | - Shasta L Sabo
- Departments of Pharmacology and Neuroscience, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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Zhang B, Chen LY, Liu X, Maxeiner S, Lee SJ, Gokce O, Südhof TC. Neuroligins Sculpt Cerebellar Purkinje-Cell Circuits by Differential Control of Distinct Classes of Synapses. Neuron 2015; 87:781-96. [PMID: 26291161 DOI: 10.1016/j.neuron.2015.07.020] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 05/25/2015] [Accepted: 07/22/2015] [Indexed: 10/23/2022]
Abstract
Neuroligins are postsynaptic cell-adhesion molecules that bind presynaptic neurexins and are genetically linked to autism. Neuroligins are proposed to organize synaptogenesis and/or synaptic transmission, but no systematic analysis of neuroligins in a defined circuit is available. Here, we show that conditional deletion of all neuroligins in cerebellar Purkinje cells caused loss of distal climbing-fiber synapses and weakened climbing-fiber but not parallel-fiber synapses, consistent with alternative use of neuroligins and cerebellins as neurexin ligands for the excitatory climbing-fiber versus parallel-fiber synapses. Moreover, deletion of neuroligins increased the size of inhibitory basket/stellate-cell synapses but simultaneously severely impaired their function. Multiple neuroligin isoforms differentially contributed to climbing-fiber and basket/stellate-cell synapse functions, such that inhibitory synapse-specific neuroligin-2 was unexpectedly essential for maintaining normal climbing-fiber synapse numbers. Using systematic analyses of all neuroligins in a defined neural circuit, our data thus show that neuroligins differentially contribute to various Purkinje-cell synapses in the cerebellum in vivo.
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Affiliation(s)
- Bo Zhang
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, Room G1021, Stanford, CA 94305, USA
| | - Lulu Y Chen
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, Room G1021, Stanford, CA 94305, USA
| | - Xinran Liu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Stephan Maxeiner
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, Room G1021, Stanford, CA 94305, USA
| | - Sung-Jin Lee
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, Room G1021, Stanford, CA 94305, USA
| | - Ozgun Gokce
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, Room G1021, Stanford, CA 94305, USA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, Room G1021, Stanford, CA 94305, USA.
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47
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Hua R, Wei M, Zhang C. The complex genetics in autism spectrum disorders. SCIENCE CHINA-LIFE SCIENCES 2015; 58:933-45. [PMID: 26335739 DOI: 10.1007/s11427-015-4893-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Autism spectrum disorders (ASD) are a pervasive neurodevelopmental disease characterized by deficits in social interaction and nonverbal communication, as well as restricted interests and stereotypical behavior. Genetic changes/heritability is one of the major contributing factors, and hundreds to thousands of causative and susceptible genes, copy number variants (CNVs), linkage regions, and microRNAs have been associated with ASD which clearly indicates that ASD is a complex genetic disorder. Here, we will briefly summarize some of the high-confidence genetic changes in ASD and their possible roles in their pathogenesis.
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Affiliation(s)
- Rui Hua
- State Key Laboratory of Membrane Biology, School of Life Sciences; PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - MengPing Wei
- State Key Laboratory of Membrane Biology, School of Life Sciences; PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Chen Zhang
- State Key Laboratory of Membrane Biology, School of Life Sciences; PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
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48
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Espinosa F, Xuan Z, Liu S, Powell CM. Neuroligin 1 modulates striatal glutamatergic neurotransmission in a pathway and NMDAR subunit-specific manner. Front Synaptic Neurosci 2015; 7:11. [PMID: 26283958 PMCID: PMC4518159 DOI: 10.3389/fnsyn.2015.00011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/18/2015] [Indexed: 12/18/2022] Open
Abstract
Together with its presynaptic partner Neurexin 1 (Nxn1), Neuroligin 1 (NL1) participates in synapse specification and synapse maintenance. We and others have shown that NL1 can also modulate glutamatergic synaptic function in the central nervous system of rodent models. These molecular/cellular changes can translate into altered animal behaviors that are thought to be analogous to symptomatology of neuropsychiatric disorders. For example, in dorsal striatum of NL1 deletion mice, we previously reported that the ratio N-methyl-D-aspartate receptor (NMDAR) mediated synaptic currents to α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptor (AMPAR) mediated synaptic currents (NMDA/AMPA) is reduced in medium spiny neuron (MSNs). Importantly, this reduction in NMDA/AMPA ratio correlated with increased repetitive grooming. The striatum is the input nucleus of the basal ganglia (BG). Classical models of this circuitry imply that there are two principal pathways that render distinct and somewhat opposite striatal outputs critical to the function of these nuclei in modulating motor behavior. Thus, we set out to better characterize the effects of NL1 deletion on direct and indirect pathways of the dorsal striatum by genetically labeling MSNs participating in the direct and indirect pathways. We demonstrate that a decrease in NMDAR-mediated currents is limited to MSNs of the direct pathway. Furthermore, the decrease in NMDAR-mediated currents is largely due to a reduction in function of NMDARs containing the GluN2A subunit. In contrast, indirect pathway MSNs in NL1 knockout (KO) mice showed a reduction in the frequency of miniature excitatory neurotransmission not observed in the direct pathway. Thus, NL1 deletion differentially affects direct and indirect pathway MSNs in dorsal striatum. These findings have potential implications for striatal function in NL1 KO mice.
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Affiliation(s)
- Felipe Espinosa
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Zhong Xuan
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Shunan Liu
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Craig M Powell
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center Dallas, TX, USA ; Neuroscience Graduate Program, The University of Texas Southwestern Medical Center Dallas, TX, USA ; Department of Psychiatry, The University of Texas Southwestern Medical Center Dallas, TX, USA
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49
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Shen DN, Zhang LH, Wei EQ, Yang Y. Autophagy in synaptic development, function, and pathology. Neurosci Bull 2015; 31:416-26. [PMID: 26139541 DOI: 10.1007/s12264-015-1536-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 05/30/2015] [Indexed: 01/04/2023] Open
Abstract
In the nervous system, neurons contact each other to form neuronal circuits and drive behavior, relying heavily on synaptic connections. The proper development and growth of synapses allows functional transmission of electrical information between neurons or between neurons and muscle fibers. Defects in synapse-formation or development lead to many diseases. Autophagy, a major determinant of protein turnover, is an essential process that takes place in developing synapses. During the induction of autophagy, proteins and cytoplasmic components are encapsulated in autophagosomes, which fuse with lysosomes to form autolysosomes. The cargoes are subsequently degraded and recycled. However, aberrant autophagic activity may lead to synaptic dysfunction, which is a common pathological characteristic in several disorders. Here, we review the current understanding of autophagy in regulating synaptic development and function. In addition, autophagy-related synaptic dysfunction in human diseases is also summarized.
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Affiliation(s)
- Dan-Na Shen
- Department of Pharmacology, Hangzhou Key Laboratory of Medical Neurobiology, School of Medicine, Hangzhou Normal University, Hangzhou, 310036, China
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50
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Minatohara K, Murata Y, Fujiyoshi Y, Doi T. An intracellular domain with a novel sequence regulates cell surface expression and synaptic clustering of leucine-rich repeat transmembrane proteins in hippocampal neurons. J Neurochem 2015; 134:618-28. [DOI: 10.1111/jnc.13159] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 04/23/2015] [Accepted: 05/05/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Keiichiro Minatohara
- Department of Biophysics; Graduate School of Science; Kyoto University; Kyoto Japan
| | - Yasunobu Murata
- Department of Biophysics; Graduate School of Science; Kyoto University; Kyoto Japan
| | - Yoshinori Fujiyoshi
- Department of Basic Medicinal Sciences; Graduate School of Pharmaceutical Sciences; Nagoya University; Nagoya Japan
- Cellular and Structural Physiology Institute; Nagoya University; Nagoya Japan
| | - Tomoko Doi
- Department of Biophysics; Graduate School of Science; Kyoto University; Kyoto Japan
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