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Pereira A, Diwakar J, Masserdotti G, Beşkardeş S, Simon T, So Y, Martín-Loarte L, Bergemann F, Vasan L, Schauer T, Danese A, Bocchi R, Colomé-Tatché M, Schuurmans C, Philpott A, Straub T, Bonev B, Götz M. Direct neuronal reprogramming of mouse astrocytes is associated with multiscale epigenome remodeling and requires Yy1. Nat Neurosci 2024; 27:1260-1273. [PMID: 38956165 PMCID: PMC11239498 DOI: 10.1038/s41593-024-01677-5] [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: 09/16/2022] [Accepted: 05/10/2024] [Indexed: 07/04/2024]
Abstract
Direct neuronal reprogramming is a promising approach to regenerate neurons from local glial cells. However, mechanisms of epigenome remodeling and co-factors facilitating this process are unclear. In this study, we combined single-cell multiomics with genome-wide profiling of three-dimensional nuclear architecture and DNA methylation in mouse astrocyte-to-neuron reprogramming mediated by Neurogenin2 (Ngn2) and its phosphorylation-resistant form (PmutNgn2), respectively. We show that Ngn2 drives multilayered chromatin remodeling at dynamic enhancer-gene interaction sites. PmutNgn2 leads to higher reprogramming efficiency and enhances epigenetic remodeling associated with neuronal maturation. However, the differences in binding sites or downstream gene activation cannot fully explain this effect. Instead, we identified Yy1, a transcriptional co-factor recruited by direct interaction with Ngn2 to its target sites. Upon deletion of Yy1, activation of neuronal enhancers, genes and ultimately reprogramming are impaired without affecting Ngn2 binding. Thus, our work highlights the key role of interactors of proneural factors in direct neuronal reprogramming.
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Affiliation(s)
- Allwyn Pereira
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
- Nantes Université, CHU Nantes, INSERM, TaRGeT - Translational Research in Gene Therapy, UMR 1089, Nantes, France
| | - Jeisimhan Diwakar
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Helmholtz Pioneer Campus, Helmholtz Center Munich, Neuherberg, Germany
| | - Giacomo Masserdotti
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
| | - Sude Beşkardeş
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Helmholtz Pioneer Campus, Helmholtz Center Munich, Neuherberg, Germany
| | - Tatiana Simon
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
| | - Younju So
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
| | - Lucía Martín-Loarte
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
| | - Franziska Bergemann
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
| | - Lakshmy Vasan
- Biological Science Platform, Sunnybrook Research Institute; Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Tamas Schauer
- Biomedical Center Munich (BMC), Bioinformatic Core Facility, Faculty of Medicine, LMU Munich, Planegg, Germany
- Institute of Stem Cells and Epigenetics, Helmholtz Center Munich, Neuherberg, Germany
| | - Anna Danese
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
| | - Riccardo Bocchi
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany
- Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Maria Colomé-Tatché
- Institute of Computational Biology, Helmholtz Center Munich, Neuherberg, Germany
- Biomedical Center Munich (BMC), Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg, Germany
| | - Carol Schuurmans
- Biological Science Platform, Sunnybrook Research Institute; Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Anna Philpott
- Wellcome-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Tobias Straub
- Biological Science Platform, Sunnybrook Research Institute; Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Boyan Bonev
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany.
- Helmholtz Pioneer Campus, Helmholtz Center Munich, Neuherberg, Germany.
| | - Magdalena Götz
- Biomedical Center Munich (BMC), Physiological Genomics, LMU Munich, Planegg, Germany.
- Institute of Stem Cell Research, Helmholtz Center Munich, BMC LMU Munich, Planegg, Germany.
- Excellence Cluster of Systems Neurology (SYNERGY), Munich, Germany.
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Bykhovskaia M. Dynamic Formation of the Protein-Lipid Pre-fusion Complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.589983. [PMID: 38659925 PMCID: PMC11042276 DOI: 10.1101/2024.04.17.589983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Synaptic vesicles (SVs) fuse with the presynaptic membrane (PM) to release neuronal transmitters. The SV protein Synaptotagmin 1 (Syt1) serves as a Ca2+ sensor for evoked fusion. Syt1 is thought to trigger fusion by penetrating into PM upon Ca2+ binding, however the mechanistic detail of this process is still debated. Syt1 interacts with the SNARE complex, a coiled-coil four-helical bundle that enables the SV-PM attachment. The SNARE-associated protein Complexin (Cpx) promotes the Ca2+-dependent fusion, possibly interacting with Syt1. We employed all-atom molecular dynamics (MD) to investigate the formation of the Syt1-SNARE-Cpx complex interacting with the lipid bilayers of PM and SV. Our simulations demonstrated that the PM-Syt1-SNARE-Cpx complex can transition to a "dead-end" state, wherein Syt1 attaches tightly to PM but does not immerse into it, as opposed to a pre-fusion state, which has the tips of the Ca2+-bound C2 domains of Syt1 inserted into PM. Our simulations unraveled the sequence of Syt1 conformational transitions, including the simultaneous Syt1 docking to the SNARE-Cpx bundle and PM, followed by the Ca2+ chelation and the penetration of the tips of Syt1 domains into PM, leading to the pre-fusion state of the protein-lipid complex. Importantly, we found that the direct Syt1-Cpx interactions are required to promote these transitions. Thus, we developed the all-atom dynamic model of the conformational transitions that lead to the formation of the pre-fusion PM-Syt1-SNARE-Cpx complex. Our simulations also revealed an alternative "dead-end" state of the protein-lipid complex that can be formed if this pathway is disrupted.
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Skuladottir AT, Stefansdottir L, Halldorsson GH, Stefansson OA, Bjornsdottir A, Jonsson P, Palmadottir V, Thorgeirsson TE, Walters GB, Gisladottir RS, Bjornsdottir G, Jonsdottir GA, Sulem P, Gudbjartsson DF, Knowlton KU, Jones DA, Ottas A, Pedersen OB, Didriksen M, Brunak S, Banasik K, Hansen TF, Erikstrup C, Haavik J, Andreassen OA, Rye D, Igland J, Ostrowski SR, Milani LA, Nadauld LD, Stefansson H, Stefansson K. GWAS meta-analysis reveals key risk loci in essential tremor pathogenesis. Commun Biol 2024; 7:504. [PMID: 38671141 PMCID: PMC11053069 DOI: 10.1038/s42003-024-06207-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
Essential tremor (ET) is a prevalent neurological disorder with a largely unknown underlying biology. In this genome-wide association study meta-analysis, comprising 16,480 ET cases and 1,936,173 controls from seven datasets, we identify 12 sequence variants at 11 loci. Evaluating mRNA expression, splicing, plasma protein levels, and coding effects, we highlight seven putative causal genes at these loci, including CA3 and CPLX1. CA3 encodes Carbonic Anhydrase III and carbonic anhydrase inhibitors have been shown to decrease tremors. CPLX1, encoding Complexin-1, regulates neurotransmitter release. Through gene-set enrichment analysis, we identify a significant association with specific cell types, including dopaminergic and GABAergic neurons, as well as biological processes like Rho GTPase signaling. Genetic correlation analyses reveals a positive association between ET and Parkinson's disease, depression, and anxiety-related phenotypes. This research uncovers risk loci, enhancing our knowledge of the complex genetics of this common but poorly understood disorder, and highlights CA3 and CPLX1 as potential therapeutic targets.
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Affiliation(s)
- Astros Th Skuladottir
- deCODE genetics/Amgen Inc., Reykjavik, Iceland.
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
| | | | | | | | | | - Palmi Jonsson
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Department of Geriatric Medicine, Landspitali University Hospital, Reykjavik, Iceland
| | - Vala Palmadottir
- Department of Internal Medicine, Landspitali University Hospital, Reykjavik, Iceland
| | | | | | - Rosa S Gisladottir
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Icelandic and Comparative Cultural Studies, University of Iceland, Reykjavik, Iceland
| | | | | | | | - Daniel F Gudbjartsson
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Engineering and Natural Sciences, University of Iceland, Reykjavik, Iceland
| | - Kirk U Knowlton
- Intermountain Medical Center, Intermountain Heart Institute, Salt Lake City, USA
| | - David A Jones
- Precision Genomics, Intermountain Healthcare, Saint George, Utah, UK
| | - Aigar Ottas
- Estonian Genome Centre, Institute of Genomics, University of Tartu, Tartu, Estonia
| | - Ole B Pedersen
- Department of Clinical Immunology, Zealand University Hospital, Køge, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maria Didriksen
- Department of Clinical Immunology, Copenhagen University Hospital, Righospitale, Copenhagen, Denmark
| | - Søren Brunak
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karina Banasik
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Folkmann Hansen
- Danish Headache Center, Department of Neurology, Copenhagen University Hospital, Righospitalet-Glostrup, Copenhagen, Denmark
| | - Christian Erikstrup
- Department of Clinical Immunology, Aarhus University Hospital, Righospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, Aarhus University, Aarhus, Denmark
| | - Jan Haavik
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Bergen Center of Brain Plasticity, Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
| | - Ole A Andreassen
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- NORMENT, Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - David Rye
- Emory Department of Neurology, Wesley Woods Health Center, Atlanta, GA, USA
| | - Jannicke Igland
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Department of Health and Caring sciences, Western Norway University of Applied Sciences, Bergen, Norway
| | - Sisse Rye Ostrowski
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Immunology, Copenhagen University Hospital, Righospitale, Copenhagen, Denmark
| | - Lili A Milani
- Estonian Genome Centre, Institute of Genomics, University of Tartu, Tartu, Estonia
| | - Lincoln D Nadauld
- Precision Genomics, Intermountain Healthcare, Saint George, Utah, UK
- Stanford University, School of Medicine, Stanford, CA, USA
| | | | - Kari Stefansson
- deCODE genetics/Amgen Inc., Reykjavik, Iceland.
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
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López-Murcia FJ, Lin KH, Berns MMM, Ranjan M, Lipstein N, Neher E, Brose N, Reim K, Taschenberger H. Complexin has a dual synaptic function as checkpoint protein in vesicle priming and as a promoter of vesicle fusion. Proc Natl Acad Sci U S A 2024; 121:e2320505121. [PMID: 38568977 PMCID: PMC11009659 DOI: 10.1073/pnas.2320505121] [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: 11/26/2023] [Accepted: 03/04/2024] [Indexed: 04/05/2024] Open
Abstract
The presynaptic SNARE-complex regulator complexin (Cplx) enhances the fusogenicity of primed synaptic vesicles (SVs). Consequently, Cplx deletion impairs action potential-evoked transmitter release. Conversely, though, Cplx loss enhances spontaneous and delayed asynchronous release at certain synapse types. Using electrophysiology and kinetic modeling, we show that such seemingly contradictory transmitter release phenotypes seen upon Cplx deletion can be explained by an additional of Cplx in the control of SV priming, where its ablation facilitates the generation of a "faulty" SV fusion apparatus. Supporting this notion, a sequential two-step priming scheme, featuring reduced vesicle fusogenicity and increased transition rates into the faulty primed state, reproduces all aberrations of transmitter release modes and short-term synaptic plasticity seen upon Cplx loss. Accordingly, we propose a dual presynaptic function for the SNARE-complex interactor Cplx, one as a "checkpoint" protein that guarantees the proper assembly of the fusion machinery during vesicle priming, and one in boosting vesicle fusogenicity.
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Affiliation(s)
- Francisco José López-Murcia
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Kun-Han Lin
- Laboratory of Membrane Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
| | - Manon M. M. Berns
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Mrinalini Ranjan
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
- Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Georg August University Göttingen, Göttingen37077, Germany
| | - Noa Lipstein
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Erwin Neher
- Laboratory of Membrane Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
- Cluster of Excellence ‘Multiscale Bioimaging’, Georg August University Göttingen, Göttingen37073, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
- Cluster of Excellence ‘Multiscale Bioimaging’, Georg August University Göttingen, Göttingen37073, Germany
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
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Yang F, Zhao Z, Zhang D, Xiong Y, Dong X, Wang Y, Yang M, Pan T, Liu C, Liu K, Lin Y, Liu Y, Tu Q, Dang Y, Xia M, Mi D, Zhou W, Xu Z. Single-cell multi-omics analysis of lineage development and spatial organization in the human fetal cerebellum. Cell Discov 2024; 10:22. [PMID: 38409116 PMCID: PMC10897198 DOI: 10.1038/s41421-024-00656-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/30/2024] [Indexed: 02/28/2024] Open
Abstract
Human cerebellum encompasses numerous neurons, exhibiting a distinct developmental paradigm from cerebrum. Here we conducted scRNA-seq, scATAC-seq and spatial transcriptomic analyses of fetal samples from gestational week (GW) 13 to 18 to explore the emergence of cellular diversity and developmental programs in the developing human cerebellum. We identified transitory granule cell progenitors that are conserved across species. Special patterns in both granule cells and Purkinje cells were dissected multidimensionally. Species-specific gene expression patterns of cerebellar lobes were characterized and we found that PARM1 exhibited inconsistent distribution in human and mouse granule cells. A novel cluster of potential neuroepithelium at the rhombic lip was identified. We also resolved various subtypes of Purkinje cells and unipolar brush cells and revealed gene regulatory networks controlling their diversification. Therefore, our study offers a valuable multi-omics landscape of human fetal cerebellum and advances our understanding of development and spatial organization of human cerebellum.
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Affiliation(s)
- Fuqiang Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Ziqi Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Dan Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Yu Xiong
- Shanghai Key Laboratory of Female Reproductive Endocrine-Related Diseases, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
| | - Xinran Dong
- Center for Molecular Medicine, Children's Hospital of Fudan University, Shanghai, China
| | - Yuchen Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Min Yang
- Department of Neonatology, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
| | | | - Chuanyu Liu
- BGI-Beijing, Beijing, China
- BGI-Shenzhen, Shenzhen, China
| | - Kaiyi Liu
- Key Laboratory of Birth Defects, Children's Hospital of Fudan University, Shanghai, China
| | - Yifeng Lin
- Key Laboratory of Birth Defects, Children's Hospital of Fudan University, Shanghai, China
| | - Yongjie Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Qiang Tu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Yashan Dang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Mingyang Xia
- Key Laboratory of Birth Defects, Children's Hospital of Fudan University, Shanghai, China.
| | - Da Mi
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China.
| | - Wenhao Zhou
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China.
| | - Zhiheng Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China.
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Zhang YH, Zhao P, Gao HL, Zhong ML, Li JY. Screening Targets and Therapeutic Drugs for Alzheimer's Disease Based on Deep Learning Model and Molecular Docking. J Alzheimers Dis 2024; 100:863-878. [PMID: 38995776 DOI: 10.3233/jad-231389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2024]
Abstract
Background Alzheimer's disease (AD) is a neurodegenerative disorder caused by a complex interplay of various factors. However, a satisfactory cure for AD remains elusive. Pharmacological interventions based on drug targets are considered the most cost-effective therapeutic strategy. Therefore, it is paramount to search potential drug targets and drugs for AD. Objective We aimed to provide novel targets and drugs for the treatment of AD employing transcriptomic data of AD and normal control brain tissues from a new perspective. Methods Our study combined the use of a multi-layer perceptron (MLP) with differential expression analysis, variance assessment and molecular docking to screen targets and drugs for AD. Results We identified the seven differentially expressed genes (DEGs) with the most significant variation (ANKRD39, CPLX1, FABP3, GABBR2, GNG3, PPM1E, and WDR49) in transcriptomic data from AD brain. A newly built MLP was used to confirm the association between the seven DEGs and AD, establishing these DEGs as potential drug targets. Drug databases and molecular docking results indicated that arbaclofen, baclofen, clozapine, arbaclofen placarbil, BML-259, BRD-K72883421, and YC-1 had high affinity for GABBR2, and FABP3 bound with oleic, palmitic, and stearic acids. Arbaclofen and YC-1 activated GABAB receptor through PI3K/AKT and PKA/CREB pathways, respectively, thereby promoting neuronal anti-apoptotic effect and inhibiting p-tau and Aβ formation. Conclusions This study provided a new strategy for the identification of targets and drugs for the treatment of AD using deep learning. Seven therapeutic targets and ten drugs were selected by using this method, providing new insight for AD treatment.
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Affiliation(s)
- Ya-Hong Zhang
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Pu Zhao
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Hui-Ling Gao
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Man-Li Zhong
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Jia-Yi Li
- Health Sciences Institute, China Medical University, Shenyang, China
- Department of Experimental Medical Science, Neuronal Plasticity and Repair Unit, Wallenberg Neuroscience Center, Lund University, Lund, Sweden
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Shi M, Xu H, Hu R, Chen Y, Wu X, Chen B, Ma R. Identification and Validation of Synapse-related Hub Genes after Spinal Cord Injury by Bioinformatics Analysis. Comb Chem High Throughput Screen 2024; 27:599-610. [PMID: 37170986 DOI: 10.2174/1386207326666230426151114] [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: 09/14/2022] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 05/13/2023]
Abstract
BACKGROUND Spinal cord injury (SCI) is a neurological disease with high morbidity and mortality. Previous studies have shown that abnormally expressed synapse-related genes are closely related to the occurrence and development of SCI. However, little is known about the interaction of these aberrantly expressed genes and the molecular mechanisms that play a role in the injury response. Therefore, deeply exploring the correlation between synapse-related genes and functional recovery after spinal cord injury and the molecular regulation mechanism is of great significance. METHODS First, we selected the function GSE45006 dataset to construct three clinically meaningful gene modules by hierarchical clustering analysis in 4 normal samples and 20 SCI samples. Subsequently, we performed functional and pathway enrichment analyses of key modules. RESULTS The results showed that related module genes were significantly enriched in synaptic structures and functions, such as the regulation of synaptic membranes and membrane potential. A protein-protein interaction network (PPI) was constructed to identify 10 hub genes of SCI, and the results showed that Snap25, Cplx1, Stxbp1, Syt1, Rims1, Rab3a, Syn2, Syn1, Cask, Lin7b were most associated with SCI. Finally, these hub genes were further verified by quantitative real-time fluorescence polymerase chain reaction (qRT-PCR) in the spinal cord tissues of the blank group and SCI rats, and it was found that the expression of these hub genes was significantly decreased in the spinal cord injury compared with the blank group (P ≤ 0.05). CONCLUSION These results suggest that the structure and function of synapses play an important role after spinal cord injury. Our study helps to understand the underlying pathogenesis of SCI patients further and identify new targets for SCI treatment.
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Affiliation(s)
- Mengting Shi
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Haipeng Xu
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Rong Hu
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Yi Chen
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Xingying Wu
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Bowen Chen
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Ruijie Ma
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine (School of Rehabilitation Medicine), Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
- Department of Acupuncture and Moxibustion, Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
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Choi J, Ehrlich ME, Roussos P, Wang P, Yuan GC, Song X. QuadST: A Powerful and Robust Approach for Identifying Cell-Cell Interaction-Changed Genes on Spatially Resolved Transcriptomics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.570019. [PMID: 38106025 PMCID: PMC10723309 DOI: 10.1101/2023.12.04.570019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Spatially resolved transcriptomics (SRT) have enabled profiling spatial organization of cells and their transcriptome in situ. Various analytical methods have been developed to uncover cell-cell interaction processes using SRT data. To improve upon existing efforts, we developed a novel statistical framework called QuadST for the robust and powerful identification of interaction-changed genes (ICGs) for cell-type-pair specific interactions on a single-cell SRT dataset. QuadST is motivated by the idea that in the presence of cell-cell interaction, gene expression level can vary with cell-cell distance between cell type pairs, which can be particularly pronounced within and in the vicinity of cell-cell interaction distance. Specifically, QuadST infers ICGs in a specific cell type pair's interaction based on a quantile regression model, which allows us to assess the strength of distance-expression association across entire distance quantiles conditioned on gene expression level. To identify ICGs, QuadST performs a hypothesis testing with an empirically estimated FDR, whose upper bound is determined by the ratio of cumulative associations at symmetrically smaller and larger distance quantiles simultaneously across all genes. Simulation studies illustrate that QuadST provides consistent FDR control and better power performance than other compared methods. Its application on SRT datasets profiled from mouse brains demonstrates that QuadST can identify ICGs presumed to play a role in specific cell type pair interactions (e.g., synaptic pathway genes among excitatory neuron cell interactions). These results suggest that QuadST can be a useful tool to discover genes and regulatory processes involved in specific cell type pair interactions.
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Affiliation(s)
- Jinmyung Choi
- Institute for Health Care Delivery Science, Department of Population Health Science and Policy, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michelle E. Ehrlich
- Departments of Neurology, Pediatrics, and Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Panos Roussos
- Center for Disease Neurogenomics, Department of Psychiatry, Department of Genetics and Genomics Sciences, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, NY, USA; Mental Illness Research Education, and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, Bronx, NY, USA
| | - Pei Wang
- Department of Genetics and Genomic Sciences, Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Guo-Cheng Yuan
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Xiaoyu Song
- Institute for Health Care Delivery Science, Department of Population Health Science and Policy, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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9
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Cukier HN, Duarte CL, Laverde-Paz MJ, Simon SA, Van Booven DJ, Miyares AT, Whitehead PL, Hamilton-Nelson KL, Adams LD, Carney RM, Cuccaro ML, Vance JM, Pericak-Vance MA, Griswold AJ, Dykxhoorn DM. An Alzheimer's disease risk variant in TTC3 modifies the actin cytoskeleton organization and the PI3K-Akt signaling pathway in iPSC-derived forebrain neurons. Neurobiol Aging 2023; 131:182-195. [PMID: 37677864 PMCID: PMC10538380 DOI: 10.1016/j.neurobiolaging.2023.07.007] [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: 05/25/2023] [Accepted: 07/11/2023] [Indexed: 09/09/2023]
Abstract
A missense variant in the tetratricopeptide repeat domain 3 (TTC3) gene (rs377155188, p.S1038C, NM_003316.4:c 0.3113C>G) was found to segregate with disease in a multigenerational family with late-onset Alzheimer's disease. This variant was introduced into induced pluripotent stem cells (iPSCs) derived from a cognitively intact individual using CRISPR genome editing, and the resulting isogenic pair of iPSC lines was differentiated into cortical neurons. Transcriptome analysis showed an enrichment for genes involved in axon guidance, regulation of actin cytoskeleton, and GABAergic synapse. Functional analysis showed that the TTC3 p.S1038C iPSC-derived neuronal progenitor cells had altered 3-dimensional morphology and increased migration, while the corresponding neurons had longer neurites, increased branch points, and altered expression levels of synaptic proteins. Pharmacological treatment with small molecules that target the actin cytoskeleton could revert many of these cellular phenotypes, suggesting a central role for actin in mediating the cellular phenotypes associated with the TTC3 p.S1038C variant.
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Affiliation(s)
- Holly N Cukier
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA; John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Carolina L Duarte
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Mayra J Laverde-Paz
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Shaina A Simon
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Derek J Van Booven
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Amanda T Miyares
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; JJ Vance Memorial Summer Internship in Biological and Computational Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Patrice L Whitehead
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Kara L Hamilton-Nelson
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Larry D Adams
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Regina M Carney
- Mental Health & Behavioral Science Service, Bruce W. Carter VA Medical Center, Miami, FL, USA
| | - Michael L Cuccaro
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jeffery M Vance
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA; John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Margaret A Pericak-Vance
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA; John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Anthony J Griswold
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Derek M Dykxhoorn
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA.
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10
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Filandrova R, Douglas P, Zhan X, Verhey TB, Morrissy S, Turner RW, Schriemer DC. Mouse Model of Fragile X Syndrome Analyzed by Quantitative Proteomics: A Comparison of Methods. J Proteome Res 2023; 22:3054-3067. [PMID: 37595185 DOI: 10.1021/acs.jproteome.3c00363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
Multiple methods for quantitative proteomics are available for proteome profiling. It is unclear which methods are most useful in situations involving deep proteome profiling and the detection of subtle distortions in the proteome. Here, we compared the performance of seven different strategies in the analysis of a mouse model of Fragile X Syndrome, involving the knockout of the fmr1 gene that is the leading cause of autism spectrum disorder. Focusing on the cerebellum, we show that data-independent acquisition (DIA) and the tandem mass tag (TMT)-based real-time search method (RTS) generated the most informative profiles, generating 334 and 329 significantly altered proteins, respectively, although the latter still suffered from ratio compression. Label-free methods such as BoxCar and a conventional data-dependent acquisition were too noisy to generate a reliable profile, while TMT methods that do not invoke RTS showed a suppressed dynamic range. The TMT method using the TMTpro reagents together with complementary ion quantification (ProC) overcomes ratio compression, but current limitations in ion detection reduce sensitivity. Overall, both DIA and RTS uncovered known regulators of the syndrome and detected alterations in calcium signaling pathways that are consistent with calcium deregulation recently observed in imaging studies. Data are available via ProteomeXchange with the identifier PXD039885.
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Affiliation(s)
- Ruzena Filandrova
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Pauline Douglas
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Xiaoqin Zhan
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Theodore B Verhey
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Sorana Morrissy
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Raymond W Turner
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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11
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Wang H, Peng K, Curry RJ, Li D, Wang Y, Wang X, Lu Y. Group I metabotropic glutamate receptor-triggered temporally patterned action potential-dependent spontaneous synaptic transmission in mouse MNTB neurons. Hear Res 2023; 435:108822. [PMID: 37285615 PMCID: PMC10330867 DOI: 10.1016/j.heares.2023.108822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/28/2023] [Accepted: 06/01/2023] [Indexed: 06/09/2023]
Abstract
Rhythmic action potentials (AP) are generated via intrinsic ionic mechanisms in pacemaking neurons, producing synaptic responses of regular inter-event intervals (IEIs) in their targets. In auditory processing, evoked temporally patterned activities are induced when neural responses timely lock to a certain phase of the sound stimuli. Spontaneous spike activity, however, is a stochastic process, rendering the prediction of the exact timing of the next event completely based on probability. Furthermore, neuromodulation mediated by metabotropic glutamate receptors (mGluRs) is not commonly associated with patterned neural activities. Here, we report an intriguing phenomenon. In a subpopulation of medial nucleus of the trapezoid body (MNTB) neurons recorded under whole-cell voltage-clamp mode in acute mouse brain slices, temporally patterned AP-dependent glycinergic sIPSCs and glutamatergic sEPSCs were elicited by activation of group I mGluRs with 3,5-DHPG (200 µM). Auto-correlation analyses revealed rhythmogenesis in these synaptic responses. Knockout of mGluR5 largely eliminated the effects of 3,5-DHPG. Cell-attached recordings showed temporally patterned spikes evoked by 3,5-DHPG in potential presynaptic VNTB cells for synaptic inhibition onto MNTB. The amplitudes of sEPSCs enhanced by 3,5-DHPG were larger than quantal size but smaller than spike-driven calyceal inputs, suggesting that non-calyceal inputs to MNTB might be responsible for the temporally patterned sEPSCs. Finally, immunocytochemical studies identified expression and localization of mGluR5 and mGluR1 in the VNTB-MNTB inhibitory pathway. Our results imply a potential central mechanism underlying the generation of patterned spontaneous spike activity in the brainstem sound localization circuit.
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Affiliation(s)
- Huimei Wang
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Kang Peng
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Rebecca J Curry
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
| | - Dong Li
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Yuan Wang
- Department of Biomedical Science, Program in Neuroscience, Florida State University College of Medicine, Tallahassee, FL, 32306, USA
| | - Xiaoyu Wang
- Department of Biomedical Science, Program in Neuroscience, Florida State University College of Medicine, Tallahassee, FL, 32306, USA
| | - Yong Lu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA.
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12
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Cukier HN, Duarte CL, Laverde-Paz MJ, Simon SA, Van Booven DJ, Miyares AT, Whitehead PL, Hamilton-Nelson KL, Adams LD, Carney RM, Cuccaro ML, Vance JM, Pericak-Vance MA, Griswold AJ, Dykxhoorn DM. An Alzheimer's disease risk variant in TTC3 modifies the actin cytoskeleton organization and the PI3K-Akt signaling pathway in iPSC-derived forebrain neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542316. [PMID: 37292815 PMCID: PMC10246004 DOI: 10.1101/2023.05.25.542316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A missense variant in the tetratricopeptide repeat domain 3 ( TTC3 ) gene (rs377155188, p.S1038C, NM_003316.4:c.3113C>G) was found to segregate with disease in a multigenerational family with late onset Alzheimer's disease. This variant was introduced into induced pluripotent stem cells (iPSCs) derived from a cognitively intact individual using CRISPR genome editing and the resulting isogenic pair of iPSC lines were differentiated into cortical neurons. Transcriptome analysis showed an enrichment for genes involved in axon guidance, regulation of actin cytoskeleton, and GABAergic synapse. Functional analysis showed that the TTC3 p.S1038C iPSC-derived neuronal progenitor cells had altered 3D morphology and increased migration, while the corresponding neurons had longer neurites, increased branch points, and altered expression levels of synaptic proteins. Pharmacological treatment with small molecules that target the actin cytoskeleton could revert many of these cellular phenotypes, suggesting a central role for actin in mediating the cellular phenotypes associated with the TTC3 p.S1038C variant. Highlights The AD risk variant TTC3 p.S1038C reduces the expression levels of TTC3 The variant modifies the expression of AD specific genes BACE1 , INPP5F , and UNC5C Neurons with the variant are enriched for genes in the PI3K-Akt pathwayiPSC-derived neurons with the alteration have increased neurite length and branchingThe variant interferes with actin cytoskeleton and is ameliorated by Cytochalasin D.
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13
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Bykhovskaia M. Molecular Dynamics Simulations of the Proteins Regulating Synaptic Vesicle Fusion. MEMBRANES 2023; 13:307. [PMID: 36984694 PMCID: PMC10058449 DOI: 10.3390/membranes13030307] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/11/2023] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
Neuronal transmitters are packaged in synaptic vesicles (SVs) and released by the fusion of SVs with the presynaptic membrane (PM). An inflow of Ca2+ into the nerve terminal triggers fusion, and the SV-associated protein Synaptotagmin 1 (Syt1) serves as a Ca2+ sensor. In preparation for fusion, SVs become attached to the PM by the SNARE protein complex, a coiled-coil bundle that exerts the force overcoming SV-PM repulsion. A cytosolic protein Complexin (Cpx) attaches to the SNARE complex and differentially regulates the evoked and spontaneous release components. It is still debated how the dynamic interactions of Syt1, SNARE proteins and Cpx lead to fusion. This problem is confounded by heterogeneity in the conformational states of the prefusion protein-lipid complex and by the lack of tools to experimentally monitor the rapid conformational transitions of the complex, which occur at a sub-millisecond scale. However, these complications can be overcome employing molecular dynamics (MDs), a computational approach that enables simulating interactions and conformational transitions of proteins and lipids. This review discusses the use of molecular dynamics for the investigation of the pre-fusion protein-lipid complex. We discuss the dynamics of the SNARE complex between lipid bilayers, as well as the interactions of Syt1 with lipids and SNARE proteins, and Cpx regulating the assembly of the SNARE complex.
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Affiliation(s)
- Maria Bykhovskaia
- Neurology Department, Wayne State University, Detroit, MI 48202, USA
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14
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Lottermoser JA, Dittman JS. Complexin Membrane Interactions: Implications for Synapse Evolution and Function. J Mol Biol 2023; 435:167774. [PMID: 35931110 PMCID: PMC9807284 DOI: 10.1016/j.jmb.2022.167774] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 02/04/2023]
Abstract
The molecules and mechanisms behind chemical synaptic transmission have been explored for decades. For several of the core proteins involved in synaptic vesicle fusion, we now have a reasonably detailed grasp of their biochemical, structural, and functional properties. Complexin is one of the key synaptic proteins for which a simple mechanistic understanding is still lacking. Living up to its name, this small protein has been associated with a variety of roles differing between synapses and between species, but little consensus has been reached on its fundamental modes of action. Much attention has been paid to its deeply conserved SNARE-binding properties, while membrane-binding features of complexin and their functional significance have yet to be explored to the same degree. In this review, we summarize the known membrane interactions of the complexin C-terminal domain and their potential relevance to its function, synaptic localization, and evolutionary history.
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Affiliation(s)
| | - Jeremy S Dittman
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, United States.
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15
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Palfreyman MT, West SE, Jorgensen EM. SNARE Proteins in Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:63-118. [PMID: 37615864 DOI: 10.1007/978-3-031-34229-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitters are stored in small membrane-bound vesicles at synapses; a subset of synaptic vesicles is docked at release sites. Fusion of docked vesicles with the plasma membrane releases neurotransmitters. Membrane fusion at synapses, as well as all trafficking steps of the secretory pathway, is mediated by SNARE proteins. The SNAREs are the minimal fusion machinery. They zipper from N-termini to membrane-anchored C-termini to form a 4-helix bundle that forces the apposed membranes to fuse. At synapses, the SNAREs comprise a single helix from syntaxin and synaptobrevin; SNAP-25 contributes the other two helices to complete the bundle. Unc13 mediates synaptic vesicle docking and converts syntaxin into the permissive "open" configuration. The SM protein, Unc18, is required to initiate and proofread SNARE assembly. The SNAREs are then held in a half-zippered state by synaptotagmin and complexin. Calcium removes the synaptotagmin and complexin block, and the SNAREs drive vesicle fusion. After fusion, NSF and alpha-SNAP unwind the SNAREs and thereby recharge the system for further rounds of fusion. In this chapter, we will describe the discovery of the SNAREs, their relevant structural features, models for their function, and the central role of Unc18. In addition, we will touch upon the regulation of SNARE complex formation by Unc13, complexin, and synaptotagmin.
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Affiliation(s)
- Mark T Palfreyman
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Sam E West
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Erik M Jorgensen
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
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16
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López-Murcia FJ, Reim K, Taschenberger H. Complexins: Ubiquitously Expressed Presynaptic Regulators of SNARE-Mediated Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:255-285. [PMID: 37615870 DOI: 10.1007/978-3-031-34229-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitter release is a spatially and temporally tightly regulated process, which requires assembly and disassembly of SNARE complexes to enable the exocytosis of transmitter-loaded synaptic vesicles (SVs) at presynaptic active zones (AZs). While the requirement for the core SNARE machinery is shared by most membrane fusion processes, SNARE-mediated fusion at AZs is uniquely regulated to allow very rapid Ca2+-triggered SV exocytosis following action potential (AP) arrival. To enable a sub-millisecond time course of AP-triggered SV fusion, synapse-specific accessory SNARE-binding proteins are required in addition to the core fusion machinery. Among the known SNARE regulators specific for Ca2+-triggered SV fusion are complexins, which are almost ubiquitously expressed in neurons. This chapter summarizes the structural features of complexins, models for their molecular interactions with SNAREs, and their roles in SV fusion.
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Affiliation(s)
- Francisco José López-Murcia
- Department of Pathology and Experimental Therapy, Institute of Neurosciences, University of Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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17
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Yang H, Wu J, Zhen S, Hu Y, Li D, Xie M, Zhu H. Proteomic analysis of spinal cord tissue in a rat model of cancer-induced bone pain. Front Mol Neurosci 2022; 15:1009615. [PMID: 36545122 PMCID: PMC9760935 DOI: 10.3389/fnmol.2022.1009615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/16/2022] [Indexed: 12/12/2022] Open
Abstract
Background Cancer-induced bone pain (CIBP) is a moderate to severe pain and seriously affects patients' quality of life. Spinal cord plays critical roles in pain generation and maintenance. Identifying differentially expressed proteins (DEPs) in spinal cord is essential to elucidate the mechanisms of cancer pain. Methods CIBP rat model was established by the intratibial inoculation of MRMT-1 cells. Positron emission tomography (PET) scan and transmission electron microscopy (TEM) were used to measure the stats of spinal cord in rats. Label free Liquid Chromatography with tandem mass spectrometry (LC-MS-MS) were used to analyze the whole proteins from the lumbar spinal cord. Differentially expressed proteins (DEPs) were performed using Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, and verified using Western blot and immunofluorescence assay. Results In the current study, CIBP rats exhibited bone damage, spontaneous pain, mechanical hyperalgesia, and impaired motor ability. In spinal cord, an hypermetabolism and functional abnormality were revealed on CIBP rats. An increase of synaptic vesicles density in active zone and a disruption of mitochondrial structure in spinal cord of CIBP rats were observed. Meanwhile, 422 DEPs, consisting of 167 up-regulated and 255 down-regulated proteins, were identified among total 1539 proteins. GO enrichment analysis indicated that the DEPs were mainly involved in catabolic process, synaptic function, and enzymic activity. KEGG pathway enrichment analysis indicated a series of pathways, including nervous system disease, hormonal signaling pathways and amino acid metabolism, were involved. Expression change of synaptic and mitochondrial related protein, such as complexin 1 (CPLX1), synaptosomal-associated protein 25 (SNAP25), synaptotagmin 1 (SYT1), aldehyde dehydrogenase isoform 1B1 (ALDH1B1), Glycine amidinotransferase (GATM) and NADH:ubiquinone oxidoreductase subunit A11 (NDUFA11), were further validated using immunofluorescence and Western blot analysis. Conclusion This study provides valuable information for understanding the mechanisms of CIBP, and supplies potential therapeutic targets for cancer pain.
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Affiliation(s)
- Heyu Yang
- Xianning Medical College, Hubei University of Science and Technology, Xianning, China
| | - Ji Wu
- Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
| | - Shuqing Zhen
- Matang Hospital of Traditional Chinese Medicine, Xianning, China
| | - Yindi Hu
- Xianning Medical College, Hubei University of Science and Technology, Xianning, China
| | - Dai Li
- Xianning Medical College, Hubei University of Science and Technology, Xianning, China
| | - Min Xie
- Xianning Medical College, Hubei University of Science and Technology, Xianning, China
| | - Haili Zhu
- Xianning Medical College, Hubei University of Science and Technology, Xianning, China,*Correspondence: Haili Zhu,
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18
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Kobbersmed JRL, Berns MMM, Ditlevsen S, Sørensen JB, Walter AM. Allosteric stabilization of calcium and phosphoinositide dual binding engages several synaptotagmins in fast exocytosis. eLife 2022; 11:74810. [PMID: 35929728 PMCID: PMC9489213 DOI: 10.7554/elife.74810] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 08/04/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic communication relies on the fusion of synaptic vesicles with the plasma membrane, which leads to neurotransmitter release. This exocytosis is triggered by brief and local elevations of intracellular Ca2+ with remarkably high sensitivity. How this is molecularly achieved is unknown. While synaptotagmins confer the Ca2+ sensitivity of neurotransmitter exocytosis, biochemical measurements reported Ca2+ affinities too low to account for synaptic function. However, synaptotagmin’s Ca2+ affinity increases upon binding the plasma membrane phospholipid PI(4,5)P2 and, vice versa, Ca2+ binding increases synaptotagmin’s PI(4,5)P2 affinity, indicating a stabilization of the Ca2+/PI(4,5)P2 dual-bound state. Here, we devise a molecular exocytosis model based on this positive allosteric stabilization and the assumptions that (1.) synaptotagmin Ca2+/PI(4,5)P2 dual binding lowers the energy barrier for vesicle fusion and that (2.) the effect of multiple synaptotagmins on the energy barrier is additive. The model, which relies on biochemically measured Ca2+/PI(4,5)P2 affinities and protein copy numbers, reproduced the steep Ca2+ dependency of neurotransmitter release. Our results indicate that each synaptotagmin engaging in Ca2+/PI(4,5)P2 dual-binding lowers the energy barrier for vesicle fusion by ~5 kBT and that allosteric stabilization of this state enables the synchronized engagement of several (typically three) synaptotagmins for fast exocytosis. Furthermore, we show that mutations altering synaptotagmin’s allosteric properties may show dominant-negative effects, even though synaptotagmins act independently on the energy barrier, and that dynamic changes of local PI(4,5)P2 (e.g. upon vesicle movement) dramatically impact synaptic responses. We conclude that allosterically stabilized Ca2+/PI(4,5)P2 dual binding enables synaptotagmins to exert their coordinated function in neurotransmission. For our brains and nervous systems to work properly, the nerve cells within them must be able to ‘talk’ to each other. They do this by releasing chemical signals called neurotransmitters which other cells can detect and respond to. Neurotransmitters are packaged in tiny membrane-bound spheres called vesicles. When a cell of the nervous system needs to send a signal to its neighbours, the vesicles fuse with the outer membrane of the cell, discharging their chemical contents for other cells to detect. The initial trigger for neurotransmitter release is a short, fast increase in the amount of calcium ions inside the signalling cell. One of the main proteins that helps regulate this process is synaptotagmin which binds to calcium and gives vesicles the signal to start unloading their chemicals. Despite acting as a calcium sensor, synaptotagmin actually has a very low affinity for calcium ions by itself, meaning that it would not be efficient for the protein to respond alone. Synpatotagmin is more likely to bind to calcium if it is attached to a molecule called PIP2, which is found in the membranes of cells The effect also occurs in reverse, as the binding of calcium to synaptotagmin increases the protein’s affinity for PIP2. However, how these three molecules – synaptotagmin, PIP2, and calcium – work together to achieve the physiological release of neurotransmitters is poorly understood. To help answer this question, Kobbersmed, Berns et al. set up a computer simulation of ‘virtual vesicles’ using available experimental data on synaptotagmin’s affinity with calcium and PIP2. In this simulation, synaptotagmin could only trigger the release of neurotransmitters when bound to both calcium and PIP2. The model also showed that each ‘complex’ of synaptotagmin/calcium/PIP2 made the vesicles more likely to fuse with the outer membrane of the cell – to the extent that only a handful of synaptotagmin molecules were needed to start neurotransmitter release from a single vesicle. These results shed new light on a biological process central to the way nerve cells communicate with each other. In the future, Kobbersmed, Berns et al. hope that this insight will help us to understand the cause of diseases where communication in the nervous system is impaired.
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Affiliation(s)
- Janus R L Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manon M M Berns
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Susanne Ditlevsen
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Alexander M Walter
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
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19
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Bera M, Ramakrishnan S, Coleman J, Krishnakumar SS, Rothman JE. Molecular determinants of complexin clamping and activation function. eLife 2022; 11:e71938. [PMID: 35442188 PMCID: PMC9020821 DOI: 10.7554/elife.71938] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Previously we reported that Synaptotagmin-1 and Complexin synergistically clamp the SNARE assembly process to generate and maintain a pool of docked vesicles that fuse rapidly and synchronously upon Ca2+ influx (Ramakrishnan et al., 2020). Here, using the same in vitro single-vesicle fusion assay, we determine the molecular details of the Complexin-mediated fusion clamp and its role in Ca2+-activation. We find that a delay in fusion kinetics, likely imparted by Synaptotagmin-1, is needed for Complexin to block fusion. Systematic truncation/mutational analyses reveal that continuous alpha-helical accessory-central domains of Complexin are essential for its inhibitory function and specific interaction of the accessory helix with the SNAREpins enhances this functionality. The C-terminal domain promotes clamping by locally elevating Complexin concentration through interactions with the membrane. Independent of their clamping functions, the accessory-central helical domains of Complexin also contribute to rapid Ca2+-synchronized vesicle release by increasing the probability of fusion from the clamped state.
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Affiliation(s)
- Manindra Bera
- Yale Nanobiology InstituteNew HavenUnited States
- Department of Cell Biology, Yale University School of MedicineNew HavenUnited States
| | - Sathish Ramakrishnan
- Yale Nanobiology InstituteNew HavenUnited States
- Department of Pathology, Yale University School of MedicineNew HavenUnited States
| | - Jeff Coleman
- Yale Nanobiology InstituteNew HavenUnited States
- Department of Cell Biology, Yale University School of MedicineNew HavenUnited States
| | - Shyam S Krishnakumar
- Yale Nanobiology InstituteNew HavenUnited States
- Departments of Neurology, Yale University School of MedicineNew HavenUnited States
| | - James E Rothman
- Yale Nanobiology InstituteNew HavenUnited States
- Department of Cell Biology, Yale University School of MedicineNew HavenUnited States
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20
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McMeekin LJ, Joyce KL, Jenkins LM, Bohannon BM, Patel KD, Bohannon AS, Patel A, Fox SN, Simmons MS, Day JJ, Kralli A, Crossman DK, Cowell RM. Estrogen-related Receptor Alpha (ERRα) is Required for PGC-1α-dependent Gene Expression in the Mouse Brain. Neuroscience 2021; 479:70-90. [PMID: 34648866 PMCID: PMC9124582 DOI: 10.1016/j.neuroscience.2021.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 09/15/2021] [Accepted: 10/04/2021] [Indexed: 11/27/2022]
Abstract
Deficiency in peroxisome proliferator-activated receptor gamma coactivator 1-alpha. (PGC-1α) expression or function is implicated in numerous neurological and psychiatric disorders. PGC-1α is required for the expression of genes involved in synchronous neurotransmitter release, axonal integrity, and metabolism, especially in parvalbumin-positive interneurons. As a transcriptional coactivator, PGC-1α requires transcription factors to specify cell-type-specific gene programs; while much is known about these factors in peripheral tissues, it is unclear if PGC-1α utilizes these same factors in neurons. Here, we identified putative transcription factors controlling PGC-1α-dependent gene expression in the brain using bioinformatics and then validated the role of the top candidate in a knockout mouse model. We transcriptionally profiled cells overexpressing PGC-1α and searched for over-represented binding motifs in the promoters of upregulated genes. Binding sites of the estrogen-related receptor (ERR) family of transcription factors were enriched, and blockade of ERRα attenuated PGC-1α-mediated induction of mitochondrial and synaptic genes in cell culture. Localization in the mouse brain revealed enrichment of ERRα expression in parvalbumin-expressing neurons with tight correlation of expression with PGC-1α across brain regions. In ERRα null mice, PGC-1α-dependent genes were reduced in multiple regions, including neocortex, hippocampus, and cerebellum, though not to the extent observed in PGC-1α null mice. Behavioral assessment revealed ambulatory hyperactivity in response to amphetamine and impairments in sensorimotor gating without the overt motor impairment characteristic of PGC-1α null mice. These data suggest that ERRα is required for normal levels of expression of PGC-1α-dependent genes in neurons but that additional factors may be involved in their regulation.
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Affiliation(s)
- L J McMeekin
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - K L Joyce
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - L M Jenkins
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - B M Bohannon
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - K D Patel
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA
| | - A S Bohannon
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - A Patel
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - S N Fox
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - M S Simmons
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - J J Day
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - A Kralli
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - D K Crossman
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - R M Cowell
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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21
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Lipstein N, Chang S, Lin KH, López-Murcia FJ, Neher E, Taschenberger H, Brose N. Munc13-1 is a Ca 2+-phospholipid-dependent vesicle priming hub that shapes synaptic short-term plasticity and enables sustained neurotransmission. Neuron 2021; 109:3980-4000.e7. [PMID: 34706220 PMCID: PMC8691950 DOI: 10.1016/j.neuron.2021.09.054] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 08/10/2021] [Accepted: 09/23/2021] [Indexed: 11/28/2022]
Abstract
During ongoing presynaptic action potential (AP) firing, transmitter release is limited by the availability of release-ready synaptic vesicles (SVs). The rate of SV recruitment (SVR) to release sites is strongly upregulated at high AP frequencies to balance SV consumption. We show that Munc13-1-an essential SV priming protein-regulates SVR via a Ca2+-phospholipid-dependent mechanism. Using knockin mouse lines with point mutations in the Ca2+-phospholipid-binding C2B domain of Munc13-1, we demonstrate that abolishing Ca2+-phospholipid binding increases synaptic depression, slows recovery of synaptic strength after SV pool depletion, and reduces temporal fidelity of synaptic transmission, while increased Ca2+-phospholipid binding has the opposite effects. Thus, Ca2+-phospholipid binding to the Munc13-1-C2B domain accelerates SVR, reduces short-term synaptic depression, and increases the endurance and temporal fidelity of neurotransmission, demonstrating that Munc13-1 is a core vesicle priming hub that adjusts SV re-supply to demand.
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Affiliation(s)
- Noa Lipstein
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Shuwen Chang
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Kun-Han Lin
- Emeritus Laboratory of Membrane Biophysics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | - Erwin Neher
- Emeritus Laboratory of Membrane Biophysics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging," Georg August University, Göttingen, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging," Georg August University, Göttingen, Germany.
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22
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Sauvola CW, Littleton JT. SNARE Regulatory Proteins in Synaptic Vesicle Fusion and Recycling. Front Mol Neurosci 2021; 14:733138. [PMID: 34421538 PMCID: PMC8377282 DOI: 10.3389/fnmol.2021.733138] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/20/2021] [Indexed: 01/01/2023] Open
Abstract
Membrane fusion is a universal feature of eukaryotic protein trafficking and is mediated by the soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) family. SNARE proteins embedded in opposing membranes spontaneously assemble to drive membrane fusion and cargo exchange in vitro. Evolution has generated a diverse complement of SNARE regulatory proteins (SRPs) that ensure membrane fusion occurs at the right time and place in vivo. While a core set of SNAREs and SRPs are common to all eukaryotic cells, a specialized set of SRPs within neurons confer additional regulation to synaptic vesicle (SV) fusion. Neuronal communication is characterized by precise spatial and temporal control of SNARE dynamics within presynaptic subdomains specialized for neurotransmitter release. Action potential-elicited Ca2+ influx at these release sites triggers zippering of SNAREs embedded in the SV and plasma membrane to drive bilayer fusion and release of neurotransmitters that activate downstream targets. Here we discuss current models for how SRPs regulate SNARE dynamics and presynaptic output, emphasizing invertebrate genetic findings that advanced our understanding of SRP regulation of SV cycling.
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Affiliation(s)
- Chad W Sauvola
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States
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23
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Lux UT, Ehrenberg J, Joachimsthaler A, Atorf J, Pircher B, Reim K, Kremers J, Gießl A, Brandstätter JH. Cell Types and Synapses Expressing the SNARE Complex Regulating Proteins Complexin 1 and Complexin 2 in Mammalian Retina. Int J Mol Sci 2021; 22:ijms22158131. [PMID: 34360929 PMCID: PMC8348166 DOI: 10.3390/ijms22158131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 11/16/2022] Open
Abstract
Complexins (Cplxs) 1 to 4 are components of the presynaptic compartment of chemical synapses where they regulate important steps in synaptic vesicle exocytosis. In the retina, all four Cplxs are present, and while we know a lot about Cplxs 3 and 4, little is known about Cplxs 1 and 2. Here, we performed in situ hybridization experiments and bioinformatics and exploited Cplx 1 and Cplx 2 single-knockout mice combined with immunocytochemistry and light microscopy to characterize in detail the cell type and synapse-specific distribution of Cplx 1 and Cplx 2. We found that Cplx 2 and not Cplx 1 is the main isoform expressed in normal and displaced amacrine cells and ganglion cells in mouse retinae and that amacrine cells seem to operate with a single Cplx isoform at their conventional chemical synapses. Surprising was the finding that retinal function, determined with electroretinographic recordings, was altered in Cplx 1 but not Cplx 2 single-knockout mice. In summary, the results provide an important basis for future studies on the function of Cplxs 1 and 2 in the processing of visual signals in the mammalian retina.
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Affiliation(s)
- Uwe Thorsten Lux
- Division of Animal Physiology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany; (U.T.L.); (J.E.); (B.P.)
| | - Johanna Ehrenberg
- Division of Animal Physiology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany; (U.T.L.); (J.E.); (B.P.)
| | - Anneka Joachimsthaler
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (A.J.); (J.A.); (J.K.); (A.G.)
| | - Jenny Atorf
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (A.J.); (J.A.); (J.K.); (A.G.)
| | - Bianca Pircher
- Division of Animal Physiology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany; (U.T.L.); (J.E.); (B.P.)
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany;
| | - Jan Kremers
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (A.J.); (J.A.); (J.K.); (A.G.)
| | - Andreas Gießl
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (A.J.); (J.A.); (J.K.); (A.G.)
| | - Johann Helmut Brandstätter
- Division of Animal Physiology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany; (U.T.L.); (J.E.); (B.P.)
- Correspondence:
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24
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Rojo Arias JE, Jászai J. Gene expression profile of the murine ischemic retina and its response to Aflibercept (VEGF-Trap). Sci Rep 2021; 11:15313. [PMID: 34321516 PMCID: PMC8319207 DOI: 10.1038/s41598-021-94500-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 07/05/2021] [Indexed: 02/07/2023] Open
Abstract
Ischemic retinal dystrophies are leading causes of acquired vision loss. Although the dysregulated expression of the hypoxia-responsive VEGF-A is a major driver of ischemic retinopathies, implication of additional VEGF-family members in their pathogenesis has led to the development of multivalent anti-angiogenic tools. Designed as a decoy receptor for all ligands of VEGFR1 and VEGFR2, Aflibercept is a potent anti-angiogenic agent. Notwithstanding, the molecular mechanisms mediating Aflibercept's efficacy remain only partially understood. Here, we used the oxygen-induced retinopathy (OIR) mouse as a model system of pathological retinal vascularization to investigate the transcriptional response of the murine retina to hypoxia and of the OIR retina to Aflibercept. While OIR severely impaired transcriptional changes normally ensuing during retinal development, analysis of gene expression patterns hinted at alterations in leukocyte recruitment during the recovery phase of the OIR protocol. Moreover, the levels of Angiopoietin-2, a major player in the progression of diabetic retinopathy, were elevated in OIR tissues and consistently downregulated by Aflibercept. Notably, GO term, KEGG pathway enrichment, and expression dynamics analyses revealed that, beyond regulating angiogenic processes, Aflibercept also modulated inflammation and supported synaptic transmission. Altogether, our findings delineate novel mechanisms potentially underlying Aflibercept's efficacy against ischemic retinopathies.
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Affiliation(s)
- Jesús Eduardo Rojo Arias
- grid.4488.00000 0001 2111 7257Department of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Saxony, Germany ,grid.5335.00000000121885934Present Address: Wellcome-MRC Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK
| | - József Jászai
- grid.4488.00000 0001 2111 7257Department of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Saxony, Germany
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25
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Bera M, Ramakrishnan S, Coleman J, Krishnakumar SS, Rothman JE. Molecular Determinants of Complexin Clamping in Reconstituted Single-Vesicle Fusion.. [DOI: 10.1101/2021.07.05.451112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
ABSTRACTPreviously we reported that Synaptotagmin-1 and Complexin synergistically clamp the SNARE assembly process to generate and maintain a pool of docked vesicles that fuse rapidly and synchronously upon Ca2+ influx (Ramakrishnan et al. 2020). Here using the same in vitro single-vesicle fusion assay, we establish the molecular details of the Complexin clamp and its physiological relevance. We find that a delay in fusion kinetics, likely imparted by Synaptotagmin-1, is needed for Complexin to block fusion. Systematic truncation/mutational analyses reveal that continuous alpha-helical accessory-central domains of Complexin are essential for its inhibitory function and specific interaction of the accessory helix with the SNAREpins, analogous to the trans clamping model, enhances this functionality. The c-terminal domain promotes clamping by locally elevating Complexin concentration through interactions with the membrane. Further, we find that Complexin likely contributes to rapid Ca2+-synchronized vesicular release by preventing un-initiated fusion rather than by directly facilitating vesicle fusion.
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26
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The Accessory Helix of Complexin Stabilizes a Partially Unzippered State of the SNARE Complex and Mediates the Complexin Clamping Function In Vivo. eNeuro 2021; 8:ENEURO.0526-20.2021. [PMID: 33692090 PMCID: PMC8026252 DOI: 10.1523/eneuro.0526-20.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/16/2021] [Accepted: 02/09/2021] [Indexed: 12/17/2022] Open
Abstract
Spontaneous synaptic transmission is regulated by the protein complexin (Cpx). Cpx binds the SNARE complex, a coil-coiled four-helical bundle that mediates the attachment of a synaptic vesicle (SV) to the presynaptic membrane (PM). Cpx is thought to clamp spontaneous fusion events by stabilizing a partially unraveled state of the SNARE bundle; however, the molecular detail of this mechanism is still debated. We combined electrophysiology, molecular modeling, and site-directed mutagenesis in Drosophila to develop and validate the atomic model of the Cpx-mediated clamped state of the SNARE complex. We took advantage of botulinum neurotoxins (BoNTs) B and G, which cleave the SNARE protein synaptobrevin (Syb) at different sites. Monitoring synaptic depression on BoNT loading revealed that the clamped state of the SNARE complex has two or three unraveled helical turns of Syb. Site-directed mutagenesis showed that the Cpx clamping function is predominantly maintained by its accessory helix (AH), while molecular modeling suggested that the Cpx AH interacts with the unraveled C terminus of Syb and the SV lipid bilayer. The developed molecular model was employed to design new Cpx poor-clamp and super-clamp mutations and to tested the predictions in silico employing molecular dynamics simulations. Subsequently, we generated Drosophila lines harboring these mutations and confirmed the poor-clamp and super-clamp phenotypes in vivo. Altogether, these results validate the atomic model of the Cpx-mediated fusion clamp, wherein the Cpx AH inserts between the SNARE bundle and the SV lipid bilayer, simultaneously binding the unraveled C terminus of Syb and preventing full SNARE assembly.
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27
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Bhoi JD, Zhang Z, Janz R, You Y, Wei H, Wu J, Ribelayga CP. The SNARE regulator Complexin3 is a target of the cone circadian clock. J Comp Neurol 2021; 529:1066-1080. [PMID: 32783205 PMCID: PMC8190822 DOI: 10.1002/cne.25004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 08/03/2020] [Accepted: 08/05/2020] [Indexed: 01/07/2023]
Abstract
BMAL1 is a core component of the mammalian circadian clockwork. Removal of BMAL1 from the retina significantly affects visual information processing in both rod and cone pathways. To identify potential pathways and/or molecules through which BMAL1 alters signal transmission at the cone pedicle, we performed an RNA-seq differential expression analysis between cone-specific Bmal1 knockout cones (cone-Bmal1-/- ) and wild-type (WT) cones. We found 88 genes differentially expressed. Among these, Complexin3 (Cplx3), a SNARE regulator at ribbon synapses, was downregulated fivefold in the mutant cones. The purpose of this work was to determine whether BMAL1 and/or the cone clock controls CPLX3 protein expression at cone pedicles. We found that CPLX3 expression level was decreased twofold in cone-Bmal1-/- cones. Furthermore, CPLX3 expression was downregulated at night compared to the day in WT cones but remained constitutively low in mutant cones both day and night. The transcript and protein expression levels of Cplx4-the other complexin expressed in cones-were similar in WT and mutant cones; in WT cones, CPLX4 protein level did not change with the time of day. In silico analysis revealed four potential BMAL1:CLOCK binding sites upstream from exon one of Cplx3 and none upstream of exon one of Cplx4. Our results suggest that CPLX3 expression is regulated at the transcriptional level by the cone clock. The modulation of CPLX3 may be a mechanism by which the clock controls the cone synaptic transfer function to second-order cells and thereby impacts retinal signal processing during the day/night cycle.
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Affiliation(s)
- Jacob D. Bhoi
- Rice University, Undergraduate Program in Neuroscience, Houston, Texas
- Summer Research Program, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Zhijing Zhang
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Roger Janz
- Department of Neurobiology and Anatomy, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
- MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Program in Neuroscience, MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Neuroscience Research Center, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Yanan You
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
- Center for Stem Cell and Regenerative Medicine, The University of Texas Brown Foundation Institute of Molecular Medicine, Houston, Texas
| | - Haichao Wei
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
- Center for Stem Cell and Regenerative Medicine, The University of Texas Brown Foundation Institute of Molecular Medicine, Houston, Texas
| | - Jiaqian Wu
- MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Program in Neuroscience, MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Neuroscience Research Center, The University of Texas Health Science Center at Houston, Houston, Texas
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
- Center for Stem Cell and Regenerative Medicine, The University of Texas Brown Foundation Institute of Molecular Medicine, Houston, Texas
| | - Christophe P. Ribelayga
- Summer Research Program, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
- MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Program in Neuroscience, MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Neuroscience Research Center, The University of Texas Health Science Center at Houston, Houston, Texas
- Program in Biochemistry and Cell Biology, MD Anderson UTHealth Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas
- Bernice Weingarten Chair in Ophthalmology, Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
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28
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Complexin-2 redistributes to the membrane of muscle cells in response to insulin and contributes to GLUT4 translocation. Biochem J 2021; 478:407-422. [DOI: 10.1042/bcj20200542] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/11/2020] [Accepted: 01/04/2021] [Indexed: 11/17/2022]
Abstract
Insulin stimulates glucose uptake in muscle cells by rapidly redistributing vesicles containing GLUT4 glucose transporters from intracellular compartments to the plasma membrane (PM). GLUT4 vesicle fusion requires the formation of SNARE complexes between vesicular VAMP and PM syntaxin4 and SNAP23. SNARE accessory proteins usually regulate vesicle fusion processes. Complexins aide in neuro-secretory vesicle-membrane fusion by stabilizing trans-SNARE complexes but their participation in GLUT4 vesicle fusion is unknown. We report that complexin-2 is expressed and homogeneously distributed in L6 rat skeletal muscle cells. Upon insulin stimulation, a cohort of complexin-2 redistributes to the PM. Complexin-2 knockdown markedly inhibited GLUT4 translocation without affecting proximal insulin signalling of Akt/PKB phosphorylation and actin fiber remodelling. Similarly, complexin-2 overexpression decreased maximal GLUT4 translocation suggesting that the concentration of complexin-2 is finely tuned to vesicle fusion. These findings reveal an insulin-dependent regulation of GLUT4 insertion into the PM involving complexin-2.
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29
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Farsi Z, Walde M, Klementowicz AE, Paraskevopoulou F, Woehler A. Single synapse glutamate imaging reveals multiple levels of release mode regulation in mammalian synapses. iScience 2020; 24:101909. [PMID: 33392479 PMCID: PMC7773578 DOI: 10.1016/j.isci.2020.101909] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/24/2020] [Accepted: 12/03/2020] [Indexed: 01/17/2023] Open
Abstract
Mammalian central synapses exhibit vast heterogeneity in signaling strength. To understand the extent of this diversity, how it is achieved, and its functional implications, characterization of a large number of individual synapses is required. Using glutamate imaging, we characterized the evoked release probability and spontaneous release frequency of over 24,000 individual synapses. We found striking variability and no correlation between action potential-evoked and spontaneous synaptic release strength, suggesting distinct regulatory mechanisms. Subpixel localization of individual evoked and spontaneous release events reveals tight spatial regulation of evoked release and enhanced spontaneous release outside of evoked release region. Using on-stage post hoc immune-labeling of vesicle-associated proteins, Ca2+-sensing proteins, and soluble presynaptic proteins we were able to show that distinct molecular ensembles are associated with evoked and spontaneous modes of synaptic release.
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Affiliation(s)
- Zohreh Farsi
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, 10115, Germany
| | - Marie Walde
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, 10115, Germany
| | - Agnieszka E Klementowicz
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, 10115, Germany
| | - Foteini Paraskevopoulou
- Institute of Neurophysiology, NeuroCure Cluster of Excellence, Charité-Universitätsmedizin, Berlin, 10115, Germany
| | - Andrew Woehler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, 10115, Germany
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30
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Systems biology reveals reprogramming of the S-nitroso-proteome in the cortical and striatal regions of mice during aging process. Sci Rep 2020; 10:13913. [PMID: 32807865 PMCID: PMC7431412 DOI: 10.1038/s41598-020-70383-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 07/28/2020] [Indexed: 12/26/2022] Open
Abstract
Cell aging depends on the rate of cumulative oxidative and nitrosative damage to DNA and proteins. Accumulated data indicate the involvement of protein S-nitrosylation (SNO), the nitric oxide (NO)-mediated posttranslational modification (PTM) of cysteine thiols, in different brain disorders. However, the changes and involvement of SNO in aging including the development of the organism from juvenile to adult state is still unknown. In this study, using the state-of-the-art mass spectrometry technology to identify S-nitrosylated proteins combined with large-scale computational biology, we tested the S-nitroso-proteome in juvenile and adult mice in both cortical and striatal regions. We found reprogramming of the S-nitroso-proteome in adult mice of both cortex and striatum regions. Significant biological processes and protein–protein clusters associated with synaptic and neuronal terms were enriched in adult mice. Extensive quantitative analysis revealed a large set of potentially pathological proteins that were significantly upregulated in adult mice. Our approach, combined with large scale computational biology allowed us to perform a system-level characterization and identification of the key proteins and biological processes that can serve as drug targets for aging and brain disorders in future studies.
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Verhage M, Sørensen JB. SNAREopathies: Diversity in Mechanisms and Symptoms. Neuron 2020; 107:22-37. [PMID: 32559416 DOI: 10.1016/j.neuron.2020.05.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/29/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022]
Abstract
Neuronal SNAREs and their key regulators together drive synaptic vesicle exocytosis and synaptic transmission as a single integrated membrane fusion machine. Human pathogenic mutations have now been reported for all eight core components, but patients are diagnosed with very different neurodevelopmental syndromes. We propose to unify these syndromes, based on etiology and mechanism, as "SNAREopathies." Here, we review the strikingly diverse clinical phenomenology and disease severity and the also remarkably diverse genetic mechanisms. We argue that disease severity generally scales with functional redundancy and, conversely, that the large effect of mutations in some SNARE genes is the price paid for extensive integration and exceptional specialization. Finally, we discuss how subtle differences in components being rate limiting in different types of neurons helps to explain the main symptoms.
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Affiliation(s)
- Matthijs Verhage
- Department of Functional Genomics, Vrije Universiteit (VU) Amsterdam, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands; Department of Clinical Genetics, UMC Amsterdam, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands.
| | - Jakob B Sørensen
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen N, Denmark.
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López-Murcia FJ, Reim K, Jahn O, Taschenberger H, Brose N. Acute Complexin Knockout Abates Spontaneous and Evoked Transmitter Release. Cell Rep 2020; 26:2521-2530.e5. [PMID: 30840877 DOI: 10.1016/j.celrep.2019.02.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/05/2018] [Accepted: 02/07/2019] [Indexed: 12/21/2022] Open
Abstract
SNARE-mediated synaptic vesicle (SV) fusion is controlled by multiple regulatory proteins that determine neurotransmitter release efficiency. Complexins are essential SNARE regulators whose mode of action is unclear, as available evidence indicates positive SV fusion facilitation and negative "fusion clamp"-like activities, with the latter occurring only in certain contexts. Because these contradictory findings likely originate in part from different experimental perturbation strategies, we attempted to resolve them by examining a conditional complexin-knockout mouse line as the most stringent genetic perturbation model available. We found that acute complexin loss after synaptogenesis in autaptic and mass-cultured hippocampal neurons reduces SV fusion probability and thus abates the rates of spontaneous, synchronous, asynchronous, and delayed transmitter release but does not affect SV priming or cause "unclamping" of spontaneous SV fusion. Thus, complexins act as facilitators of SV fusion but are dispensable for "fusion clamping" in mammalian forebrain neurons.
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Affiliation(s)
- Francisco José López-Murcia
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Olaf Jahn
- Proteomics Group, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; DFG-Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; DFG-Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany.
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; DFG-Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany.
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Lauretti E, Nenov M, Dincer O, Iuliano L, Praticò D. Extra virgin olive oil improves synaptic activity, short-term plasticity, memory, and neuropathology in a tauopathy model. Aging Cell 2020; 19:e13076. [PMID: 31762202 PMCID: PMC6974729 DOI: 10.1111/acel.13076] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/09/2019] [Accepted: 10/30/2019] [Indexed: 12/14/2022] Open
Abstract
In recent years, increasing evidence has accumulated supporting the health benefits of extra virgin olive oil (EVOO). Previous studies showed that EVOO supplementation improves Alzheimer's disease (AD)‐like amyloidotic phenotype of transgenic mice. However, while much attention has been focused on EVOO‐mediated modulation of Aβ processing, its direct influence on tau metabolism in vivo and synaptic function is still poorly characterized. In this study, we investigated the effect of chronic supplementation of EVOO on the phenotype of a relevant mouse model of tauopathy, human transgenic tau mice (hTau). Starting at 6 months of age, hTau mice were fed chow diet supplemented with EVOO or vehicle for additional 6 months, and then the effect on their phenotype was assessed. At the end of the treatment, compared with control mice receiving EVOO displayed improved memory and cognition which was associated with increased basal synaptic activity and short‐term plasticity. This effect was accompanied by an upregulation of complexin 1, a key presynaptic protein. Moreover, EVOO treatment resulted in a significant reduction of tau oligomers and phosphorylated tau at specific epitopes. Our findings demonstrate that EVOO directly improves synaptic activity, short‐term plasticity, and memory while decreasing tau neuropathology in the hTau mice. These results strengthen the healthy benefits of EVOO and further support the therapeutic potential of this natural product not only for AD but also for primary tauopathies.
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Affiliation(s)
- Elisabetta Lauretti
- Alzheimer’s Center at Temple Lewis Katz School of Medicine Temple University Philadelphia Pennsylvania
| | - Miroslav Nenov
- Alzheimer’s Center at Temple Lewis Katz School of Medicine Temple University Philadelphia Pennsylvania
| | - Ozlem Dincer
- Alzheimer’s Center at Temple Lewis Katz School of Medicine Temple University Philadelphia Pennsylvania
| | - Luigi Iuliano
- Department of Medico‐Surgical Sciences and Biotechnology Sapienza University of Rome Latina Italy
- UOC Internal Medicine ICOT University Hospital Sapienza University of Rome Latina Italy
| | - Domenico Praticò
- Alzheimer’s Center at Temple Lewis Katz School of Medicine Temple University Philadelphia Pennsylvania
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Courtney NA, Bao H, Briguglio JS, Chapman ER. Synaptotagmin 1 clamps synaptic vesicle fusion in mammalian neurons independent of complexin. Nat Commun 2019; 10:4076. [PMID: 31501440 PMCID: PMC6733930 DOI: 10.1038/s41467-019-12015-w] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/12/2019] [Indexed: 02/01/2023] Open
Abstract
Synaptic vesicle (SV) exocytosis is mediated by SNARE proteins. Reconstituted SNAREs are constitutively active, so a major focus has been to identify fusion clamps that regulate their activity in synapses: the primary candidates are synaptotagmin (syt) 1 and complexin I/II. Syt1 is a Ca2+ sensor for SV release that binds Ca2+ via tandem C2-domains, C2A and C2B. Here, we first determined whether these C2-domains execute distinct functions. Remarkably, the C2B domain profoundly clamped all forms of SV fusion, despite synchronizing residual evoked release and rescuing the readily-releasable pool. Release was strongly enhanced by an adjacent C2A domain, and by the concurrent binding of complexin to trans-SNARE complexes. Knockdown of complexin had no impact on C2B-mediated clamping of fusion. We postulate that the C2B domain of syt1, independent of complexin, is the molecular clamp that arrests SVs prior to Ca2+-triggered fusion.
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Affiliation(s)
- Nicholas A Courtney
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Huan Bao
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Joseph S Briguglio
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Edwin R Chapman
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
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Wang X, Zhang J, Zhou L, Xu B, Ren X, He K, Nie L, Li X, Liu J, Yang X, Yuan J. Long-term iron exposure causes widespread molecular alterations associated with memory impairment in mice. Food Chem Toxicol 2019; 130:242-252. [PMID: 31136779 DOI: 10.1016/j.fct.2019.05.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/09/2019] [Accepted: 05/24/2019] [Indexed: 12/14/2022]
Abstract
Limited literature available indicates the neurotoxic effects of excessive iron, however, a deep understanding of iron neurotoxicity needs to be developed. In this study, we evaluated the toxic effects of excessive iron on learning and cognitive function in long-term iron exposure (oral, 10 mg/L, 6 months) of mice by behavioral tests including novel object recognition test, step-down passive avoidance test and Morris water maze test, and further analyzed differential expression of hippocampal proteins. The behavioral tests consistently showed that iron treatment caused cognitive defects of the mice. Proteomic analysis revealed 66 differentially expressed hippocampal proteins (30 increased and 36 decreased) in iron-treated mice as compared with the control ones. Bioinformatics analysis showed that the dysregulated proteins mainly included: synapse-associated proteins (i.e. synaptosomal-associated protein 25 (SNAP25), complexin-1 (CPLX1), vesicle-associated membrane protein 2 (VAMP2), neurochondrin (NCDN)); mitochondria-related proteins (i.e. ADP/ATP translocase 1 (SLC25A4), 14-3-3 protein zeta/delta (YWHAZ)); cytoskeleton proteins (i.e. neurofilament light polypeptide (NEFL), tubulin beta-2B chain (TUBB2B), tubulin alpha-4A chain (TUBA4A)). The findings suggest that the dysregulations of synaptic, mitochondrial, and cytoskeletal proteins may be involved in iron-triggered memory impairment. This study provides new insights into the molecular mechanisms of iron neurotoxicity.
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Affiliation(s)
- Xian Wang
- Department of Occupational and Environmental Health and Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, Hubei, PR China; Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Jiafei Zhang
- Department of Occupational and Environmental Health and Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, Hubei, PR China; Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Li Zhou
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Benhong Xu
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Xiaohu Ren
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Kaiwu He
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Lulin Nie
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Xiao Li
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China
| | - Jianjun Liu
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China.
| | - Xifei Yang
- Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, Guangdong, PR China.
| | - Jing Yuan
- Department of Occupational and Environmental Health and Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, Wuhan, 430030, Hubei, PR China.
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Pangrsic T, Singer JH, Koschak A. Voltage-Gated Calcium Channels: Key Players in Sensory Coding in the Retina and the Inner Ear. Physiol Rev 2019; 98:2063-2096. [PMID: 30067155 DOI: 10.1152/physrev.00030.2017] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Calcium influx through voltage-gated Ca (CaV) channels is the first step in synaptic transmission. This review concerns CaV channels at ribbon synapses in primary sense organs and their specialization for efficient coding of stimuli in the physical environment. Specifically, we describe molecular, biochemical, and biophysical properties of the CaV channels in sensory receptor cells of the retina, cochlea, and vestibular apparatus, and we consider how such properties might change over the course of development and contribute to synaptic plasticity. We pay particular attention to factors affecting the spatial arrangement of CaV channels at presynaptic, ribbon-type active zones, because the spatial relationship between CaV channels and release sites has been shown to affect synapse function critically in a number of systems. Finally, we review identified synaptopathies affecting sensory systems and arising from dysfunction of L-type, CaV1.3, and CaV1.4 channels or their protein modulatory elements.
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Affiliation(s)
- Tina Pangrsic
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
| | - Joshua H Singer
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
| | - Alexandra Koschak
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
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Singh M, Miura P, Renden R. Age-related defects in short-term plasticity are reversed by acetyl-L-carnitine at the mouse calyx of Held. Neurobiol Aging 2018; 67:108-119. [PMID: 29656010 PMCID: PMC5955853 DOI: 10.1016/j.neurobiolaging.2018.03.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 03/13/2018] [Accepted: 03/13/2018] [Indexed: 12/19/2022]
Abstract
Hearing acuity and sound localization are affected by aging and may contribute to cognitive dementias. Although loss of sensorineural conduction is well documented to occur with age, little is known regarding short-term synaptic plasticity in central auditory nuclei. Age-related changes in synaptic transmission properties were evaluated at the mouse calyx of Held, a sign-inverting relay synapse in the circuit for sound localization, in juvenile adults (1 month old) and late middle-aged (18-21 months old) mice. Synaptic timing and short-term plasticity were severely disrupted in older mice. Surprisingly, acetyl-l-carnitine (ALCAR), an anti-inflammatory agent that facilitates mitochondrial function, fully reversed synaptic transmission delays and defects in short-term plasticity in aged mice to reflect transmission similar to that seen in juvenile adults. These findings support ALCAR supplementation as an adjuvant to improve short-term plasticity and potentially central nervous system performance in animals compromised by age and/or neurodegenerative disease.
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Affiliation(s)
- Mahendra Singh
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Pedro Miura
- Department of Biology, University of Nevada, Reno, Reno, NV, USA
| | - Robert Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA.
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Robinson SW, Bourgognon JM, Spiers JG, Breda C, Campesan S, Butcher A, Mallucci GR, Dinsdale D, Morone N, Mistry R, Smith TM, Guerra-Martin M, Challiss RAJ, Giorgini F, Steinert JR. Nitric oxide-mediated posttranslational modifications control neurotransmitter release by modulating complexin farnesylation and enhancing its clamping ability. PLoS Biol 2018; 16:e2003611. [PMID: 29630591 PMCID: PMC5890968 DOI: 10.1371/journal.pbio.2003611] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/20/2018] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) regulates neuronal function and thus is critical for tuning neuronal communication. Mechanisms by which NO modulates protein function and interaction include posttranslational modifications (PTMs) such as S-nitrosylation. Importantly, cross signaling between S-nitrosylation and prenylation can have major regulatory potential. However, the exact protein targets and resulting changes in function remain elusive. Here, we interrogated the role of NO-dependent PTMs and farnesylation in synaptic transmission. We found that NO compromises synaptic function at the Drosophila neuromuscular junction (NMJ) in a cGMP-independent manner. NO suppressed release and reduced the size of available vesicle pools, which was reversed by glutathione (GSH) and occluded by genetic up-regulation of GSH-generating and de-nitrosylating glutamate-cysteine-ligase and S-nitroso-glutathione reductase activities. Enhanced nitrergic activity led to S-nitrosylation of the fusion-clamp protein complexin (cpx) and altered its membrane association and interactions with active zone (AZ) and soluble N-ethyl-maleimide-sensitive fusion protein Attachment Protein Receptor (SNARE) proteins. Furthermore, genetic and pharmacological suppression of farnesylation and a nitrosylation mimetic mutant of cpx induced identical physiological and localization phenotypes as caused by NO. Together, our data provide evidence for a novel physiological nitrergic molecular switch involving S-nitrosylation, which reversibly suppresses farnesylation and thereby enhances the net-clamping function of cpx. These data illustrate a new mechanistic signaling pathway by which regulation of farnesylation can fine-tune synaptic release.
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Affiliation(s)
- Susan W. Robinson
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - Jereme G. Spiers
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Carlo Breda
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Susanna Campesan
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Adrian Butcher
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Giovanna R. Mallucci
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David Dinsdale
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Raj Mistry
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Tim M. Smith
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - R. A. John Challiss
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Joern R. Steinert
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- * E-mail:
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Williams CL, Smith SM. Calcium dependence of spontaneous neurotransmitter release. J Neurosci Res 2018; 96:335-347. [PMID: 28699241 PMCID: PMC5766384 DOI: 10.1002/jnr.24116] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 06/16/2017] [Accepted: 06/19/2017] [Indexed: 01/14/2023]
Abstract
Spontaneous release of neurotransmitters is regulated by extracellular [Ca2+ ] and intracellular [Ca2+ ]. Curiously, some of the mechanisms of Ca2+ signaling at central synapses are different at excitatory and inhibitory synapses. While the stochastic activity of voltage-activated Ca2+ channels triggers a majority of spontaneous release at inhibitory synapses, this is not the case at excitatory nerve terminals. Ca2+ release from intracellular stores regulates spontaneous release at excitatory and inhibitory terminals, as do agonists of the Ca2+ -sensing receptor. Molecular machinery triggering spontaneous vesicle fusion may differ from that underlying evoked release and may be one of the sources of heterogeneity in release mechanisms.
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Affiliation(s)
- Courtney L Williams
- Department of Medicine, Division of Pulmonary & Critical Care Medicine, Oregon Health & Science University, Portland, Oregon
- Section of Pulmonary & Critical Care Medicine, VA Portland Health Care System, Portland, Oregon
| | - Stephen M Smith
- Department of Medicine, Division of Pulmonary & Critical Care Medicine, Oregon Health & Science University, Portland, Oregon
- Section of Pulmonary & Critical Care Medicine, VA Portland Health Care System, Portland, Oregon
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Cell-Specific Deletion of PGC-1α from Medium Spiny Neurons Causes Transcriptional Alterations and Age-Related Motor Impairment. J Neurosci 2018; 38:3273-3286. [PMID: 29491012 DOI: 10.1523/jneurosci.0848-17.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 02/13/2018] [Accepted: 02/17/2018] [Indexed: 01/24/2023] Open
Abstract
Multiple lines of evidence indicate that a reduction in the expression and function of the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) is associated with neurodegeneration in diseases such as Huntington's disease (HD). Polymorphisms in the PGC-1α gene modify HD progression and PGC-1α expression is reduced in striatal medium spiny neurons (MSNs) of HD patients and mouse models. However, neither the MSN-specific function of PGC-1α nor the contribution of PGC-1α deficiency to motor dysfunction is known. We identified novel, PGC-1α-dependent transcripts involved in RNA processing, signal transduction, and neuronal morphology and confirmed reductions in these transcripts in male and female mice lacking PGC-1α specifically in MSNs, indicating a cell-autonomous effect in this population. MSN-specific PGC-1α deletion caused reductions in previously identified neuronal and metabolic PGC-1α-dependent genes without causing striatal vacuolizations. Interestingly, these mice exhibited a hypoactivity with age, similar to several HD animal models. However, these newly identified PGC-1α-dependent genes were upregulated with disease severity and age in knock-in HD mouse models independent of changes in PGC-1α transcript, contrary to what would be predicted from a loss-of-function etiological mechanism. These data indicate that PGC-1α is necessary for MSN transcriptional homeostasis and function with age and that, whereas PGC-1α loss in MSNs does not replicate an HD-like phenocopy, its downstream genes are altered in a repeat-length and age-dependent fashion. Understanding the additive effects of PGC-1α gene functional variation and mutant huntingtin on transcription in this cell type may provide insight into the selective vulnerability of MSNs in HD.SIGNIFICANCE STATEMENT Reductions in peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α)-mediated transcription have been implicated in the pathogenesis of Huntington's disease (HD). We show that, although PGC-1α-dependent transcription is necessary to maintain medium spiny neuron (MSN) function with age, its loss is insufficient to cause striatal atrophy in mice. We also highlight a set of genes that can serve as proxies for PGC-1α functional activity in the striatum for target engagement studies. Furthermore, we demonstrate that PGC-1α-dependent genes are upregulated in a dose- and age-dependent fashion in HD mouse models, contrary to what would be predicted from a loss-of-function etiological mechanism. However, given this role for PGC-1α in MSN transcriptional homeostasis, it is important to consider how genetic variation in PGC-1α could contribute to mutant-huntingtin-induced cell death and disease progression.
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Hastoy B, Clark A, Rorsman P, Lang J. Fusion pore in exocytosis: More than an exit gate? A β-cell perspective. Cell Calcium 2017; 68:45-61. [PMID: 29129207 DOI: 10.1016/j.ceca.2017.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/17/2017] [Accepted: 10/24/2017] [Indexed: 12/14/2022]
Abstract
Secretory vesicle exocytosis is a fundamental biological event and the process by which hormones (like insulin) are released into the blood. Considerable progress has been made in understanding this precisely orchestrated sequence of events from secretory vesicle docked at the cell membrane, hemifusion, to the opening of a membrane fusion pore. The exact biophysical and physiological regulation of these events implies a close interaction between membrane proteins and lipids in a confined space and constrained geometry to ensure appropriate delivery of cargo. We consider some of the still open questions such as the nature of the initiation of the fusion pore, the structure and the role of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (SNARE) transmembrane domains and their influence on the dynamics and regulation of exocytosis. We discuss how the membrane composition and protein-lipid interactions influence the likelihood of the nascent fusion pore forming. We relate these factors to the hypothesis that fusion pore expansion could be affected in type-2 diabetes via changes in disease-related gene transcription and alterations in the circulating lipid profile. Detailed characterisation of the dynamics of the fusion pore in vitro will contribute to understanding the larger issue of insulin secretory defects in diabetes.
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Affiliation(s)
- Benoit Hastoy
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK.
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK; Metabolic Research, Institute of Neuroscience and Physiology, University of Goteborg, Medicinaregatan 11, S-41309 Göteborg, Sweden
| | - Jochen Lang
- Laboratoire de Chimie et Biologie des Membranes et Nano-objets (CBMN), CNRS UMR 5248, Université de Bordeaux, Allée de Geoffrey St Hilaire, 33600 Pessac, France.
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Functional Roles of Complexin 3 and Complexin 4 at Mouse Photoreceptor Ribbon Synapses. J Neurosci 2017; 36:6651-67. [PMID: 27335398 DOI: 10.1523/jneurosci.4335-15.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 05/10/2016] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Complexins (Cplxs) are SNARE complex regulators controlling the speed and Ca(2+) sensitivity of SNARE-mediated synaptic vesicle fusion. We have shown previously that photoreceptor ribbon synapses in mouse retina are equipped with Cplx3 and Cplx4 and that lack of both Cplxs perturbs photoreceptor ribbon synaptic function; however, Cplx3/4 function in photoreceptor synaptic transmission remained elusive. To investigate Cplx3/4 function in photoreceptor ribbon synapses, voltage-clamp recordings from postsynaptic horizontal cells were performed in horizontal slice preparations of Cplx3/4 wild-type (WT) and Cplx3/4 double knock-out (DKO) mice. We measured tonic activity in light and dark, current responses to changes in luminous intensity, and electrically evoked postsynaptic responses. Cplx3/4 decreased the frequency of tonic events and shifted their amplitude distribution to smaller values. Light responses were sustained in the presence of Cplx3/4, but transient in their absence. Finally, Cplx3/4 increased synaptic vesicle release evoked by electrical stimulation. Using electron microscopy, we quantified the number of synaptic vesicles at presynaptic ribbons after light or dark adaptation. In Cplx3/4 WT photoreceptors, the number of synaptic vesicles associated with the ribbon base close to the release site was significantly lower in light than in dark. This is in contrast to Cplx3/4 DKO photoreceptors, in which the number of ribbon-associated synaptic vesicles remained unchanged regardless of the adaptational state. Our results indicate a suppressing and a facilitating action of Cplx3/4 on Ca(2+)-dependent tonic and evoked neurotransmitter release, respectively, and a regulatory role in the adaptation-dependent availability of synaptic vesicles for release at photoreceptor ribbon synapses. SIGNIFICANCE STATEMENT Synaptic vesicle fusion at active zones of chemical synapses is executed by SNARE complexes. Complexins (Cplxs) are SNARE complex regulators and photoreceptor ribbon synapses are equipped with Cplx3 and Cplx4. The absence of both Cplxs perturbs ribbon synaptic function. Because we lack information on Cplx function in photoreceptor synaptic transmission, we investigated Cplx function using voltage-clamp recordings from postsynaptic horizontal cells of Cplx3/4 wild-type and Cplx3/4 double knock-out mice and quantified synaptic vesicle number at the ribbon after light and dark adaptation using electron microscopy. The findings reveal a suppressing action of Cplx3/4 on tonic neurotransmitter release, a facilitating action on evoked release, and a regulatory role of Cplx3/4 in the adaptation-dependent availability of synaptic vesicles at mouse photoreceptor ribbon synapses.
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Wragg RT, Parisotto DA, Li Z, Terakawa MS, Snead D, Basu I, Weinstein H, Eliezer D, Dittman JS. Evolutionary Divergence of the C-terminal Domain of Complexin Accounts for Functional Disparities between Vertebrate and Invertebrate Complexins. Front Mol Neurosci 2017; 10:146. [PMID: 28603484 PMCID: PMC5445133 DOI: 10.3389/fnmol.2017.00146] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 04/30/2017] [Indexed: 12/19/2022] Open
Abstract
Complexin is a critical presynaptic protein that regulates both spontaneous and calcium-triggered neurotransmitter release in all synapses. Although the SNARE-binding central helix of complexin is highly conserved and required for all known complexin functions, the remainder of the protein has profoundly diverged across the animal kingdom. Striking disparities in complexin inhibitory activity are observed between vertebrate and invertebrate complexins but little is known about the source of these differences or their relevance to the underlying mechanism of complexin regulation. We found that mouse complexin 1 (mCpx1) failed to inhibit neurotransmitter secretion in Caenorhabditis elegans neuromuscular junctions lacking the worm complexin 1 (CPX-1). This lack of inhibition stemmed from differences in the C-terminal domain (CTD) of mCpx1. Previous studies revealed that the CTD selectively binds to highly curved membranes and directs complexin to synaptic vesicles. Although mouse and worm complexin have similar lipid binding affinity, their last few amino acids differ in both hydrophobicity and in lipid binding conformation, and these differences strongly impacted CPX-1 inhibitory function. Moreover, function was not maintained if a critical amphipathic helix in the worm CPX-1 CTD was replaced with the corresponding mCpx1 amphipathic helix. Invertebrate complexins generally shared more C-terminal similarity with vertebrate complexin 3 and 4 isoforms, and the amphipathic region of mouse complexin 3 significantly restored inhibitory function to worm CPX-1. We hypothesize that the CTD of complexin is essential in conferring an inhibitory function to complexin, and that this inhibitory activity has been attenuated in the vertebrate complexin 1 and 2 isoforms. Thus, evolutionary changes in the complexin CTD differentially shape its synaptic role across phylogeny.
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Affiliation(s)
- Rachel T Wragg
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
| | - Daniel A Parisotto
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
| | - Zhenlong Li
- Department of Physiology and Biophysics, Weill Cornell Medical College, New YorkNY, United States
| | - Mayu S Terakawa
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
| | - David Snead
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
| | - Ishani Basu
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medical College, New YorkNY, United States.,Institute for Computational Biomedicine, Weill Cornell Medical College, New YorkNY, United States
| | - David Eliezer
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
| | - Jeremy S Dittman
- Department of Biochemistry, Weill Cornell Medical College, New YorkNY, United States
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44
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Mannironi C, Biundo A, Rajendran S, De Vito F, Saba L, Caioli S, Zona C, Ciotti T, Caristi S, Perlas E, Del Vecchio G, Bozzoni I, Rinaldi A, Mele A, Presutti C. miR-135a Regulates Synaptic Transmission and Anxiety-Like Behavior in Amygdala. Mol Neurobiol 2017; 55:3301-3315. [PMID: 28488209 DOI: 10.1007/s12035-017-0564-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/17/2017] [Indexed: 02/03/2023]
Abstract
MicroRNAs are a class of non-coding RNAs with a growing relevance in the regulation of gene expression related to brain function and plasticity. They have the potential to orchestrate complex phenomena, such as the neuronal response to homeostatic challenges. We previously demonstrated the involvement of miR-135a in the regulation of early stress response. In the present study, we examine the role of miR-135a in stress-related behavior. We show that the knockdown (KD) of miR-135a in the mouse amygdala induces an increase in anxiety-like behavior. Consistently with behavioral studies, electrophysiological experiments in acute brain slices indicate an increase of amygdala spontaneous excitatory postsynaptic currents, as a result of miR-135a KD. Furthermore, we presented direct evidences, by in vitro assays and in vivo miRNA overexpression in the amygdala, that two key regulators of synaptic vesicle fusion, complexin-1 and complexin-2, are direct targets of miR-135a. In vitro analysis of miniature excitatory postsynaptic currents on miR-135a KD primary neurons indicates unpaired quantal excitatory neurotransmission. Finally, increased levels of complexin-1 and complexin-2 proteins were detected in the mouse amygdala after acute stress, accordingly to the previously observed stress-induced miR-135a downregulation. Overall, our results unravel a previously unknown miRNA-dependent mechanism in the amygdala for regulating anxiety-like behavior, providing evidences of a physiological role of miR-135a in the modulation of presynaptic mechanisms of glutamatergic neurotransmission.
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Affiliation(s)
- Cecilia Mannironi
- Istituto di Biologia e Patologia Molecolari, CNR, c/o Sapienza Universita' di Roma, Rome, Italy.
| | - Antonio Biundo
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
| | - Samyutha Rajendran
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
- Istituto di Biologia Cellulare e Neurobiologia, CNR, Rome, Italy
- Centro di Ricerca in Neurobiologia "D. Bovet", Sapienza Universita' di Roma, Rome, Italy
| | | | - Luana Saba
- Fondazione Santa Lucia, I.R.C.C.S, Rome, Italy
| | | | - Cristina Zona
- Fondazione Santa Lucia, I.R.C.C.S, Rome, Italy
- Dipartimento di Medicina dei Sistemi, Universita' di Roma "Tor Vergata", Rome, Italy
| | - Teresa Ciotti
- Istituto di Biologia Cellulare e Neurobiologia, CNR, Rome, Italy
| | - Silvana Caristi
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
| | - Emerald Perlas
- Mouse Biology Unit, European Molecular Biology Laboratory (EMBL), Monterotondo Scalo, Rome, Italy
| | - Giorgia Del Vecchio
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
| | - Irene Bozzoni
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
| | - Arianna Rinaldi
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
- Istituto di Biologia Cellulare e Neurobiologia, CNR, Rome, Italy
- Centro di Ricerca in Neurobiologia "D. Bovet", Sapienza Universita' di Roma, Rome, Italy
| | - Andrea Mele
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
- Istituto di Biologia Cellulare e Neurobiologia, CNR, Rome, Italy
- Centro di Ricerca in Neurobiologia "D. Bovet", Sapienza Universita' di Roma, Rome, Italy
| | - Carlo Presutti
- Istituto di Biologia e Patologia Molecolari, CNR, c/o Sapienza Universita' di Roma, Rome, Italy
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Universita' di Roma, Rome, Italy
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Redler S, Strom TM, Wieland T, Cremer K, Engels H, Distelmaier F, Schaper J, Küchler A, Lemke JR, Jeschke S, Schreyer N, Sticht H, Koch M, Lüdecke HJ, Wieczorek D. Variants in CPLX1 in two families with autosomal-recessive severe infantile myoclonic epilepsy and ID. Eur J Hum Genet 2017; 25:889-893. [PMID: 28422131 DOI: 10.1038/ejhg.2017.52] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 02/07/2017] [Accepted: 02/17/2017] [Indexed: 12/21/2022] Open
Abstract
For a large number of individuals with intellectual disability (ID), the molecular basis of the disorder is still unknown. However, whole-exome sequencing (WES) is providing more and more insights into the genetic landscape of ID. In the present study, we performed trio-based WES in 311 patients with unsolved ID and additional clinical features, and identified homozygous CPLX1 variants in three patients with ID from two unrelated families. All displayed marked developmental delay and migrating myoclonic epilepsy, and one showed a cerebellar cleft in addition. The encoded protein, complexin 1, is crucially involved in neuronal synaptic regulation, and homozygous Cplx1 knockout mice have the earliest known onset of ataxia seen in a mouse model. Recently, a homozygous truncating variant in CPLX1 was suggested to be causative for migrating epilepsy and structural brain abnormalities. ID was not reported although it cannot be completely ruled out. However, the currently limited knowledge on CPLX1 suggests that loss of complexin 1 function may lead to a complex but variable clinical phenotype, and our findings encourage further investigations of CPLX1 in patients with ID, developmental delay and myoclonic epilepsy to unravel the phenotypic spectrum of carriers of CPLX1 variants.
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Affiliation(s)
- Silke Redler
- Heinrich-Heine-University, Medical Faculty, Institute of Human Genetics, Düsseldorf, Germany
| | - Tim M Strom
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Thomas Wieland
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Kirsten Cremer
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Hartmut Engels
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Jörg Schaper
- Heinrich-Heine-University, Medical Faculty, Department of Diagnostic and Interventional Radiology, Düsseldorf, Germany
| | - Alma Küchler
- Institute of Human Genetics, University of Duisburg-Essen, Essen, Germany
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig, Leipzig, Germany
| | - Stephanie Jeschke
- Institute of Human Genetics, University of Leipzig, Leipzig, Germany
| | - Nicole Schreyer
- Institute of Human Genetics, University of Leipzig, Leipzig, Germany
| | - Heinrich Sticht
- Institute of Biochemistry, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Margarete Koch
- Children's Hospital Datteln, University Witten/Herdecke, Datteln, Germany
| | - Hermann-Josef Lüdecke
- Heinrich-Heine-University, Medical Faculty, Institute of Human Genetics, Düsseldorf, Germany.,Institute of Human Genetics, University of Duisburg-Essen, Essen, Germany
| | - Dagmar Wieczorek
- Heinrich-Heine-University, Medical Faculty, Institute of Human Genetics, Düsseldorf, Germany.,Institute of Human Genetics, University of Duisburg-Essen, Essen, Germany
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Vasin A, Volfson D, Littleton JT, Bykhovskaia M. Interaction of the Complexin Accessory Helix with Synaptobrevin Regulates Spontaneous Fusion. Biophys J 2016; 111:1954-1964. [PMID: 27806277 PMCID: PMC5102999 DOI: 10.1016/j.bpj.2016.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 09/13/2016] [Accepted: 09/15/2016] [Indexed: 11/30/2022] Open
Abstract
Neuronal transmitters are released from nerve terminals via the fusion of synaptic vesicles with the plasma membrane. Vesicles attach to membranes via a specialized protein machinery composed of membrane-attached (t-SNARE) and vesicle-attached (v-SNARE) proteins that zipper together to form a coiled-coil SNARE bundle that brings the two fusing membranes into close proximity. Neurotransmitter release may occur either in response to an action potential or through spontaneous fusion. A cytosolic protein, Complexin (Cpx), binds the SNARE complex and restricts spontaneous exocytosis by acting as a fusion clamp. We previously proposed a model in which the interaction between Cpx and the v-SNARE serves as a spring to prevent premature zippering of the SNARE complex, thereby reducing the likelihood of fusion. To test this model, we combined molecular-dynamics (MD) simulations and site-directed mutagenesis of Cpx and SNAREs in Drosophila. MD simulations of the Drosophila Cpx-SNARE complex demonstrated that Cpx's interaction with the v-SNARE promotes unraveling of the v-SNARE off the core SNARE bundle. We investigated clamping properties in the syx3-69 paralytic mutant, which has a single-point mutation in the t-SNARE and displays enhanced spontaneous release. MD simulations demonstrated an altered interaction of Cpx with the SNARE bundle that hindered v-SNARE unraveling by Cpx, thus compromising clamping. We used our model to predict mutations that should enhance the ability of Cpx to prevent full assembly of the SNARE complex. MD simulations predicted that a weakened interaction between the Cpx accessory helix and the v-SNARE would enhance Cpx flexibility and thus promote separation of SNAREs, reducing spontaneous fusion. We generated transgenic Drosophila with mutations in Cpx and the v-SNARE that disrupted a salt bridge between these two proteins. As predicted, both lines demonstrated a selective inhibition in spontaneous release, suggesting that Cpx acts as a fusion clamp that restricts full SNARE zippering.
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Affiliation(s)
- Alexander Vasin
- Department of Neurology, Wayne State University, Detroit, Michigan
| | - Dina Volfson
- Massachusetts Institute of Technology, Cambridge, Massachusetts
| | | | - Maria Bykhovskaia
- Department of Neurology, Wayne State University, Detroit, Michigan; Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan.
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47
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Superpriming of synaptic vesicles as a common basis for intersynapse variability and modulation of synaptic strength. Proc Natl Acad Sci U S A 2016; 113:E4548-57. [PMID: 27432975 DOI: 10.1073/pnas.1606383113] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glutamatergic synapses show large variations in strength and short-term plasticity (STP). We show here that synapses displaying an increased strength either after posttetanic potentiation (PTP) or through activation of the phospholipase-C-diacylglycerol pathway share characteristic properties with intrinsically strong synapses, such as (i) pronounced short-term depression (STD) during high-frequency stimulation; (ii) a conversion of that STD into a sequence of facilitation followed by STD after a few conditioning stimuli at low frequency; (iii) an equalizing effect of such conditioning stimulation, which reduces differences among synapses and abolishes potentiation; and (iv) a requirement of long periods of rest for reconstitution of the original STP pattern. These phenomena are quantitatively described by assuming that a small fraction of "superprimed" synaptic vesicles are in a state of elevated release probability (p ∼ 0.5). This fraction is variable in size among synapses (typically about 30%), but increases after application of phorbol ester or during PTP. The majority of vesicles, released during repetitive stimulation, have low release probability (p ∼ 0.1), are relatively uniform in number across synapses, and are rapidly recruited. In contrast, superprimed vesicles need several seconds to be regenerated. They mediate enhanced synaptic strength at the onset of burst-like activity, the impact of which is subject to modulation by slow modulatory transmitter systems.
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48
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Kochubey O, Babai N, Schneggenburger R. A Synaptotagmin Isoform Switch during the Development of an Identified CNS Synapse. Neuron 2016; 90:984-99. [DOI: 10.1016/j.neuron.2016.04.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 02/26/2016] [Accepted: 04/20/2016] [Indexed: 01/08/2023]
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49
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Complexin 3 Increases the Fidelity of Signaling in a Retinal Circuit by Regulating Exocytosis at Ribbon Synapses. Cell Rep 2016; 15:2239-2250. [PMID: 27239031 PMCID: PMC5134263 DOI: 10.1016/j.celrep.2016.05.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/21/2016] [Accepted: 04/27/2016] [Indexed: 11/24/2022] Open
Abstract
Complexin (Cplx) proteins modulate the core SNARE complex to regulate exocytosis. To understand the contributions of Cplx to signaling in a well-characterized neural circuit, we investigated how Cplx3, a retina-specific paralog, shapes transmission at rod bipolar (RB) → AII amacrine cell synapses in the mouse retina. Knockout of Cplx3 strongly attenuated fast, phasic Ca2+-dependent transmission, dependent on local [Ca2+] nanodomains, but enhanced slower Ca2+-dependent transmission, dependent on global intraterminal [Ca2+] ([Ca2+]I). Surprisingly, coordinated multivesicular release persisted at Cplx3−/− synapses, although its onset was slowed. Light-dependent signaling at Cplx3−/− RB → AII synapses was sluggish, owing largely to increased asynchronous release at light offset. Consequently, propagation of RB output to retinal ganglion cells was suppressed dramatically. Our study links Cplx3 expression with synapse and circuit function in a specific retinal pathway and reveals a role for asynchronous release in circuit gain control.
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50
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Trimbuch T, Rosenmund C. Should I stop or should I go? The role of complexin in neurotransmitter release. Nat Rev Neurosci 2016; 17:118-25. [PMID: 26806630 DOI: 10.1038/nrn.2015.16] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
When it comes to fusion with the neuronal cell membrane, does a synaptic vesicle have a choice whether to stop or to go? Recent work suggests that complexin, a tiny protein found within the synaptic terminal, contributes to the mechanism through which this choice is made. How complexin plays this consulting part and which synaptic vesicle proteins it interacts with remain open questions. Indeed, studies in mice and flies have led to the proposal of different models of complexin function. We suggest that understanding the modular nature of complexin will help us to unpick its role in synaptic vesicle release.
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Affiliation(s)
- Thorsten Trimbuch
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Chariteplatz 1, 10117 Berlin, Germany
| | - Christian Rosenmund
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Chariteplatz 1, 10117 Berlin, Germany
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