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Vicidomini R, Choudhury SD, Han TH, Nguyen TH, Nguyen P, Opazo F, Serpe M. Versatile nanobody-based approach to image, track and reconstitute functional Neurexin-1 in vivo. Nat Commun 2024; 15:6068. [PMID: 39025931 PMCID: PMC11258300 DOI: 10.1038/s41467-024-50462-2] [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: 11/22/2022] [Accepted: 07/10/2024] [Indexed: 07/20/2024] Open
Abstract
Neurexins are key adhesion proteins that coordinate extracellular and intracellular synaptic components. Nonetheless, the low abundance of these multidomain proteins has complicated any localization and structure-function studies. Here we combine an ALFA tag (AT)/nanobody (NbALFA) tool with classic genetics, cell biology and electrophysiology to examine the distribution and function of the Drosophila Nrx-1 in vivo. We generate full-length and ΔPDZ ALFA-tagged Nrx-1 variants and find that the PDZ binding motif is key to Nrx-1 surface expression. A PDZ binding motif provided in trans, via genetically encoded cytosolic NbALFA-PDZ chimera, fully restores the synaptic localization and function of NrxΔPDZ-AT. Using cytosolic NbALFA-mScarlet intrabody, we achieve compartment-specific detection of endogenous Nrx-1, track live Nrx-1 transport along the motor neuron axons, and demonstrate that Nrx-1 co-migrates with Rab2-positive vesicles. Our findings illustrate the versatility of the ALFA system and pave the way towards dissecting functional domains of complex proteins in vivo.
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Affiliation(s)
- Rosario Vicidomini
- Section on Cellular Communication, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Saumitra Dey Choudhury
- Section on Cellular Communication, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
- Centralized Core Research Facility-Microscopy, All India Institute of Medical Sciences, New Delhi, Delhi, India
| | - Tae Hee Han
- Section on Cellular Communication, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Tho Huu Nguyen
- Section on Cellular Communication, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Peter Nguyen
- Section on Cellular Communication, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Felipe Opazo
- Department of Neuro and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- NanoTag Biotechnologies GmbH, Göttingen, Germany
| | - Mihaela Serpe
- Section on Cellular Communication, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.
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2
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Qin L, Liu Z, Guo S, Han Y, Wang X, Ren W, Chen J, Zhen H, Nie C, Xing KK, Chen T, Südhof TC, Sun Y, Zhang B. Astrocytic Neuroligin-3 influences gene expression and social behavior, but is dispensable for synapse number. Mol Psychiatry 2024:10.1038/s41380-024-02659-6. [PMID: 39003414 DOI: 10.1038/s41380-024-02659-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/26/2024] [Accepted: 07/02/2024] [Indexed: 07/15/2024]
Abstract
Neuroligin-3 (Nlgn3) is an autism-associated cell-adhesion molecule that interacts with neurexins and is robustly expressed in both neurons and astrocytes. Neuronal Nlgn3 is an essential regulator of synaptic transmission but the function of astrocytic Nlgn3 is largely unknown. Given the high penetrance of Nlgn3 mutations in autism and the emerging role of astrocytes in neuropsychiatric disorders, we here asked whether astrocytic Nlgn3 might shape neural circuit properties in the cerebellum similar to neuronal Nlgn3. Imaging of tagged Nlgn3 protein produced by CRISPR/Cas9-mediated genome editing showed that Nlgn3 is enriched in the cell body but not the fine processes of cerebellar astrocytes (Bergmann glia). Astrocyte-specific knockout of Nlgn3 did not detectably alter the number of synapses, synaptic transmission, or astrocyte morphology in mouse cerebellum. However, spatial transcriptomic analyses revealed a significant shift in gene expression among multiple cerebellar cell types after the deletion of astrocytic Nlgn3. Hence, in contrast to neuronal Nlgn3, astrocytic Nlgn3 in the cerebellum is not involved in shaping synapses but may modulate gene expression in specific brain areas.
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Affiliation(s)
- Liming Qin
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Zhili Liu
- BGI Research, Shenzhen, 518083, China
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Sile Guo
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Ying Han
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Xiankun Wang
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Wen Ren
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Jiewen Chen
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Hefu Zhen
- BGI Research, Shenzhen, 518083, China
| | - Chao Nie
- BGI Research, Shenzhen, 518083, China
| | - Ke-Ke Xing
- Department of Anatomy and K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, 710032, China
| | - Tao Chen
- Department of Anatomy and K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, 710032, China
| | - Thomas C Südhof
- Department of molecular and cellular physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, 94043, USA.
| | - Yuzhe Sun
- BGI Research, Shenzhen, 518083, China.
- BGI Research, 102601, Beijing, China.
- Shenzhen Key Laboratory of Neurogenomics, BGI-Shenzhen, Shenzhen, 518120, China.
| | - Bo Zhang
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, 518132, China.
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3
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Christophers B, Leahy SN, Soffar DB, von Saucken VE, Broadie K, Baylies MK. Muscle cofilin alters neuromuscular junction postsynaptic development to strengthen functional neurotransmission. Development 2024; 151:dev202558. [PMID: 38869008 PMCID: PMC11266751 DOI: 10.1242/dev.202558] [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: 11/21/2023] [Accepted: 06/05/2024] [Indexed: 06/14/2024]
Abstract
Cofilin, an actin-severing protein, plays key roles in muscle sarcomere addition and maintenance. Our previous work found that Drosophila cofilin (DmCFL) knockdown in muscle causes progressive deterioration of muscle structure and function and produces features seen in nemaline myopathy caused by cofilin mutations. We hypothesized that disruption of actin cytoskeleton dynamics by DmCFL knockdown would impact other aspects of muscle development, and, thus, conducted an RNA-sequencing analysis that unexpectedly revealed upregulated expression of numerous neuromuscular junction (NMJ) genes. We found that DmCFL is enriched in the muscle postsynaptic compartment and that DmCFL muscle knockdown causes F-actin disorganization in this subcellular domain prior to the sarcomere defects observed later in development. Despite NMJ gene expression changes, we found no significant changes in gross presynaptic Bruchpilot active zones or total postsynaptic glutamate receptor levels. However, DmCFL knockdown resulted in mislocalization of GluRIIA class glutamate receptors in more deteriorated muscles and strongly impaired NMJ transmission strength. These findings expand our understanding of the roles of cofilin in muscle to include NMJ structural development and suggest that NMJ defects may contribute to the pathophysiology of nemaline myopathy.
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Affiliation(s)
- Briana Christophers
- Weill Cornell–Rockefeller–Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Shannon N. Leahy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - David B. Soffar
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Victoria E. von Saucken
- Weill Cornell–Rockefeller–Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Kennedy Center for Research on Human Development, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - Mary K. Baylies
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
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4
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Ricardo PC, Arias MC, de Souza Araujo N. Decoding bee cleptoparasitism through comparative transcriptomics of Coelioxoides waltheriae and its host Tetrapedia diversipes. Sci Rep 2024; 14:12361. [PMID: 38811580 PMCID: PMC11137135 DOI: 10.1038/s41598-024-56261-5] [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: 08/23/2023] [Accepted: 03/04/2024] [Indexed: 05/31/2024] Open
Abstract
Cleptoparasitism, also known as brood parasitism, is a widespread strategy among bee species in which the parasite lays eggs into the nests of the host species. Even though this behavior has significant ecological implications for the dynamics of several species, little is known about the molecular pathways associated with cleptoparasitism. To shed some light on this issue, we used gene expression data to perform a comparative analysis between two solitary neotropical bees: Coelioxoides waltheriae, an obligate parasite, and their specific host Tetrapedia diversipes. We found that ortholog genes involved in signal transduction, sensory perception, learning, and memory formation were differentially expressed between the cleptoparasite and the host. We hypothesize that these genes and their associated molecular pathways are engaged in cleptoparasitism-related processes and, hence, are appealing subjects for further investigation into functional and evolutionary aspects of cleptoparasitism in bees.
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Affiliation(s)
- Paulo Cseri Ricardo
- Departamento de Genética e Biologia Evolutiva - Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
| | - Maria Cristina Arias
- Departamento de Genética e Biologia Evolutiva - Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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5
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Guangming G, Mei C, Qinfeng Y, Xiang G, Chenchen Z, Qingyuan S, Wei X, Junhua G. Neurexin and neuroligins jointly regulate synaptic degeneration at the Drosophila neuromuscular junction based on TEM studies. Front Cell Neurosci 2023; 17:1257347. [PMID: 38026694 PMCID: PMC10646337 DOI: 10.3389/fncel.2023.1257347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/12/2023] [Indexed: 12/01/2023] Open
Abstract
The Drosophila larval neuromuscular junction (NMJ) is a well-known model system and is often used to study synapse development. Here, we show synaptic degeneration at NMJ boutons, primarily based on transmission electron microscopy (TEM) studies. When degeneration starts, the subsynaptic reticulum (SSR) swells, retracts and folds inward, and the residual SSR then degenerates into a disordered, thin or linear membrane. The axon terminal begins to degenerate from the central region, and the T-bar detaches from the presynaptic membrane with clustered synaptic vesicles to accelerate large-scale degeneration. There are two degeneration modes for clear synaptic vesicles. In the first mode, synaptic vesicles without actin filaments degenerate on the membrane with ultrafine spots and collapse and disperse to form an irregular profile with dark ultrafine particles. In the second mode, clear synaptic vesicles with actin filaments degenerate into dense synaptic vesicles, form irregular dark clumps without a membrane, and collapse and disperse to form an irregular profile with dark ultrafine particles. Last, all residual membranes in NMJ boutons degenerate into a linear shape, and all the residual elements in axon terminals degenerate and eventually form a cluster of dark ultrafine particles. Swelling and retraction of the SSR occurs prior to degradation of the axon terminal, which degenerates faster and with more intensity than the SSR. NMJ bouton degeneration occurs under normal physiological conditions but is accelerated in Drosophila neurexin (dnrx) dnrx273, Drosophila neuroligin (dnlg) dnlg1 and dnlg4 mutants and dnrx83;dnlg3 and dnlg2;dnlg3 double mutants, which suggests that both neurexin and neuroligins play a vital role in preventing synaptic degeneration.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Chen Mei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Yu Qinfeng
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Gao Xiang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Sheng Qingyuan
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Xie Wei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu, China
| | - Geng Junhua
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- Shenzhen Research Institute of Southeast University, Shenzhen, Guangdong, China
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6
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Sun Y, Li M, Geng J, Meng S, Tu R, Zhuang Y, Sun M, Rui M, Ou M, Xing G, Johnson TK, Xie W. Neuroligin 2 governs synaptic morphology and function through RACK1-cofilin signaling in Drosophila. Commun Biol 2023; 6:1056. [PMID: 37853189 PMCID: PMC10584876 DOI: 10.1038/s42003-023-05428-3] [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: 02/08/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023] Open
Abstract
Neuroligins are transmembrane cell adhesion proteins well-known for their genetic links to autism spectrum disorders. Neuroligins can function by regulating the actin cytoskeleton, however the factors and mechanisms involved are still largely unknown. Here, using the Drosophila neuromuscular junction as a model, we reveal that F-Actin assembly at the Drosophila NMJ is controlled through Cofilin signaling mediated by an interaction between DNlg2 and RACK1, factors not previously known to work together. The deletion of DNlg2 displays disrupted RACK1-Cofilin signaling pathway with diminished actin cytoskeleton proteo-stasis at the terminal of the NMJ, aberrant NMJ structure, reduced synaptic transmission, and abnormal locomotion at the third-instar larval stage. Overexpression of wildtype and activated Cofilin in muscles are sufficient to rescue the morphological and physiological defects in dnlg2 mutants, while inactivated Cofilin is not. Since the DNlg2 paralog DNlg1 is known to regulate F-actin assembly mainly via a specific interaction with WAVE complex, our present work suggests that the orchestration of F-actin by Neuroligins is a diverse and complex process critical for neural connectivity.
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Affiliation(s)
- Yichen Sun
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Moyi Li
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China.
- Jiangsu Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
| | - Junhua Geng
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Sibie Meng
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Renjun Tu
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Yan Zhuang
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Mingkuan Sun
- The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Menglong Rui
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Mengzhu Ou
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Guangling Xing
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Travis K Johnson
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia
- Department of Biochemistry and Chemistry, and La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC, 3086, Australia
| | - Wei Xie
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China.
- Jiangsu Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
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Rand MD, Tennessen JM, Mackay TFC, Anholt RRH. Perspectives on the Drosophila melanogaster Model for Advances in Toxicological Science. Curr Protoc 2023; 3:e870. [PMID: 37639638 PMCID: PMC10463236 DOI: 10.1002/cpz1.870] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The use of Drosophila melanogaster for studies of toxicology has grown considerably in the last decade. The Drosophila model has long been appreciated as a versatile and powerful model for developmental biology and genetics because of its ease of handling, short life cycle, low cost of maintenance, molecular genetic accessibility, and availability of a wide range of publicly available strains and data resources. These features, together with recent unique developments in genomics and metabolomics, make the fly model especially relevant and timely for the development of new approach methodologies and movements toward precision toxicology. Here, we offer a perspective on how flies can be leveraged to identify risk factors relevant to environmental exposures and human health. First, we review and discuss fundamental toxicologic principles for experimental design with Drosophila. Next, we describe quantitative and systems genetics approaches to resolve the genetic architecture and candidate pathways controlling susceptibility to toxicants. Finally, we summarize the current state and future promise of the emerging field of Drosophila metabolomics for elaborating toxic mechanisms. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Matthew D. Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | | | - Trudy F. C. Mackay
- Center for Human Genetics and Department of Genetics and Biochemistry, Clemson University, 114 Gregor Mendel Circle, Greenwood, South Carolina 29646, USA
| | - Robert R. H. Anholt
- Center for Human Genetics and Department of Genetics and Biochemistry, Clemson University, 114 Gregor Mendel Circle, Greenwood, South Carolina 29646, USA
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8
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Chen S, Venkatesan A, Lin YQ, Xie J, Neely G, Banerjee S, Bhat MA. Drosophila Homolog of the Human Carpenter Syndrome Linked Gene, MEGF8, Is Required for Synapse Development and Function. J Neurosci 2022; 42:7016-7030. [PMID: 35944997 PMCID: PMC9480877 DOI: 10.1523/jneurosci.0442-22.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 11/21/2022] Open
Abstract
Drosophila multiple epidermal growth factor-like domains 8 (dMegf8) is a homolog of human MEGF8 MEGF8 encodes a multidomain transmembrane protein which is highly conserved across species. In humans, MEGF8 mutations cause a rare genetic disorder called Carpenter syndrome, which is frequently associated with abnormal left-right patterning, cardiac defects, and learning disabilities. MEGF8 is also associated with psychiatric disorders. Despite its clinical relevance, MEGF8 remains poorly characterized; and although it is highly conserved, studies on animal models of Megf8 are also very limited. The presence of intellectual disabilities in Carpenter syndrome patients and association of MEGF8 with psychiatric disorders indicate that mutations in MEGF8 cause underlying defects in synaptic structure and functions. In this study, we investigated the role of Drosophila dMegf8 in glutamatergic synapses of the larval neuromuscular junctions (NMJ) in both males and females. We show that dMegf8 localizes to NMJ synapses and is required for proper synaptic growth. dMegf8 mutant larvae and adults show severe motor coordination deficits. At the NMJ, dMegf8 mutants show altered localization of presynaptic and postsynaptic proteins, defects in synaptic ultrastructure, and neurotransmission. Interestingly, dMegf8 mutants have reduced levels of the Type II BMP receptor Wishful thinking (Wit). dMegf8 displays genetic interactions with neurexin-1 (dnrx) and wit, and in association with Dnrx and Wit plays an essential role in synapse organization. Our studies provide insights into human MEGF8 functions and potentially into mechanisms that may underlie intellectual disabilities observed in Carpenter syndrome as well as MEGF8-related synaptic structural and/or functional deficits in psychiatric disorders.SIGNIFICANCE STATEMENT Carpenter syndrome, known for over a century now, is a genetic disorder linked to mutations in Multiple Epidermal Growth Factor-like Domains 8 (MEGF8) gene and associated with intellectual disabilities among other symptoms. MEGF8 is also associated with psychiatric disorders. Despite the high genetic conservation and clinical relevance, the functions of MEGF8 remain largely uncharacterized. Patients with intellectual disabilities and psychiatric diseases often have an underlying defect in synaptic structure and function. This work defines the role of the fly homolog of human MEGF8, dMegf8, in glutamatergic synapse growth, organization, and function and provide insights into potential functions of MEGF8 in human central synapses and synaptic mechanisms that may underlie psychiatric disorders and intellectual disabilities seen in Carpenter syndrome.
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Affiliation(s)
- Shuting Chen
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
- Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China
| | - Anand Venkatesan
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
| | - Yong Qi Lin
- Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales Australia 2006
| | - Jing Xie
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
- Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China
| | - Gregory Neely
- Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales Australia 2006
| | - Swati Banerjee
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
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9
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Hayes AJ, Farrugia BL, Biose IJ, Bix GJ, Melrose J. Perlecan, A Multi-Functional, Cell-Instructive, Matrix-Stabilizing Proteoglycan With Roles in Tissue Development Has Relevance to Connective Tissue Repair and Regeneration. Front Cell Dev Biol 2022; 10:856261. [PMID: 35433700 PMCID: PMC9010944 DOI: 10.3389/fcell.2022.856261] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/28/2022] [Indexed: 12/19/2022] Open
Abstract
This review highlights the multifunctional properties of perlecan (HSPG2) and its potential roles in repair biology. Perlecan is ubiquitous, occurring in vascular, cartilaginous, adipose, lymphoreticular, bone and bone marrow stroma and in neural tissues. Perlecan has roles in angiogenesis, tissue development and extracellular matrix stabilization in mature weight bearing and tensional tissues. Perlecan contributes to mechanosensory properties in cartilage through pericellular interactions with fibrillin-1, type IV, V, VI and XI collagen and elastin. Perlecan domain I - FGF, PDGF, VEGF and BMP interactions promote embryonic cellular proliferation, differentiation, and tissue development. Perlecan domain II, an LDLR-like domain interacts with lipids, Wnt and Hedgehog morphogens. Perlecan domain III binds FGF-7 and 18 and has roles in the secretion of perlecan. Perlecan domain IV, an immunoglobulin repeat domain, has cell attachment and matrix stabilizing properties. Perlecan domain V promotes tissue repair through interactions with VEGF, VEGF-R2 and α2β1 integrin. Perlecan domain-V LG1-LG2 and LG3 fragments antagonize these interactions. Perlecan domain V promotes reconstitution of the blood brain barrier damaged by ischemic stroke and is neurogenic and neuroprotective. Perlecan-VEGF-VEGFR2, perlecan-FGF-2 and perlecan-PDGF interactions promote angiogenesis and wound healing. Perlecan domain I, III and V interactions with platelet factor-4 and megakaryocyte and platelet inhibitory receptor promote adhesion of cells to implants and scaffolds in vascular repair. Perlecan localizes acetylcholinesterase in the neuromuscular junction and is of functional significance in neuromuscular control. Perlecan mutation leads to Schwartz-Jampel Syndrome, functional impairment of the biomechanical properties of the intervertebral disc, variable levels of chondroplasia and myotonia. A greater understanding of the functional working of the neuromuscular junction may be insightful in therapeutic approaches in the treatment of neuromuscular disorders. Tissue engineering of salivary glands has been undertaken using bioactive peptides (TWSKV) derived from perlecan domain IV. Perlecan TWSKV peptide induces differentiation of salivary gland cells into self-assembling acini-like structures that express salivary gland biomarkers and secrete α-amylase. Perlecan also promotes chondroprogenitor stem cell maturation and development of pluripotent migratory stem cell lineages, which participate in diarthrodial joint formation, and early cartilage development. Recent studies have also shown that perlecan is prominently expressed during repair of adult human articular cartilage. Perlecan also has roles in endochondral ossification and bone development. Perlecan domain I hydrogels been used in tissue engineering to establish heparin binding growth factor gradients that promote cell migration and cartilage repair. Perlecan domain I collagen I fibril scaffolds have also been used as an FGF-2 delivery system for tissue repair. With the availability of recombinant perlecan domains, the development of other tissue repair strategies should emerge in the near future. Perlecan co-localization with vascular elastin in the intima, acts as a blood shear-flow endothelial sensor that regulates blood volume and pressure and has a similar role to perlecan in canalicular fluid, regulating bone development and remodeling. This complements perlecan's roles in growth plate cartilage and in endochondral ossification to form the appendicular and axial skeleton. Perlecan is thus a ubiquitous, multifunctional, and pleomorphic molecule of considerable biological importance. A greater understanding of its diverse biological roles and functional repertoires during tissue development, growth and disease will yield valuable insights into how this impressive proteoglycan could be utilized successfully in repair biology.
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Affiliation(s)
- Anthony J. Hayes
- Bioimaging Research Hub, Cardiff School of Biosciences, Cardiff University, Wales, United Kingdom
| | - Brooke L. Farrugia
- Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Ifechukwude J. Biose
- Departments of Neurosurgery and Neurology, Clinical Neuroscience Research Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - Gregory J. Bix
- Departments of Neurosurgery and Neurology, Clinical Neuroscience Research Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - James Melrose
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
- Raymond Purves Bone and Joint Research Laboratories, Kolling Institute of Medical Research, Royal North Shore Hospital, The Faculty of Medicine and Health, The University of Sydney, St. Leonard’s, NSW, Australia
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10
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Gunderson JT, Peppriell AE, Krout IN, Vorojeikina D, Rand MD. Neuroligin-1 Is a Mediator of Methylmercury Neuromuscular Toxicity. Toxicol Sci 2021; 184:236-251. [PMID: 34546366 DOI: 10.1093/toxsci/kfab114] [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: 11/13/2022] Open
Abstract
Methylmercury (MeHg) is a developmental toxicant capable of eliciting neurocognitive and neuromuscular deficits in children with in utero exposure. Previous research in Drosophila melanogaster uncovered that developmental MeHg exposure simultaneously targets the developing musculature and innervating motor neuron in the embryo, along with identifying Drosophila neuroligin 1 (nlg1) as a gene associated with developmental MeHg sensitivity. Nlg1 and its transsynaptic partner neurexin 1 (Nrx1) are critical for axonal arborization and NMJ maturation. We investigated the effects of MeHg exposure on indirect flight muscle (IFM) morphogenesis, innervation, and function via flight assays and monitored the expression of NMJ-associated genes to characterize the role of Nlg1 mediating the neuromuscular toxicity of MeHg. Developmental MeHg exposure reduced the innervation of the IFMs, which corresponded with reduced flight ability. In addition, nlg1 expression was selectively reduced during early metamorphosis, whereas a subsequent increase was observed in other NMJ-associated genes, including nrx1, in late metamorphosis. Developmental MeHg exposure also resulted in persistent reduced expression of most nlg and nrx genes during the first 11 days of adulthood. Transgenic modulation of nlg1 and nrx1 revealed that developing muscle is particularly sensitive to nlg1 levels, especially during the 20-36-h window of metamorphosis with reduced nlg1 expression resulting in adult flight deficits. Muscle-specific overexpression of nlg1 partially rescued MeHg-induced deficits in eclosion and flight. We identified Nlg1 as a muscle-specific, NMJ structural component that can mediate MeHg neuromuscular toxicity resulting from early life exposure.
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Affiliation(s)
- Jakob T Gunderson
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Ashley E Peppriell
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Ian N Krout
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Matthew D Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
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11
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Improved analysis method of neuromuscular junction in Drosophila larvae by transmission electron microscopy. Anat Sci Int 2021; 97:147-154. [PMID: 34661863 PMCID: PMC8732911 DOI: 10.1007/s12565-021-00635-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/04/2021] [Indexed: 11/04/2022]
Abstract
The Drosophila neuromuscular junction is an excellent model for neuroscience research. However, the distribution of neuromuscular junctions is very diffuse, and it is not easy to accurately locate during ultrathin sectioning, which seriously interferes with the ultrastructural analysis under electron microscopy that only has a small field of view. Here, we reported an efficient method for acquiring the ultrastructural picture of neuromuscular junctions in Drosophila larva under electron microscopy. The procedure was as follows: first, the larval sample of body wall muscle was placed between the metal mesh and was dehydrated with alcohol and infiltrated with epoxy resin to prevent the sample from curling or bending, after it was dissected and fixed into thin slices. Second, the sample was embedded in resin into a flat sheet to facilitate the positioning of the muscles. Third, carefully and gradually remove the excess resin and the cuticle of the larvae, cut off both ends of the special body segment, and trim the excess specific muscles according to the recommended ratio of trimming muscles, which would reduce the workload exponentially. At last, the trimmed sample were prepared into serial about 1000 ultrathin sections that was about total 80 microns thickness, and 30–40 sections were gathered into a grid to stain with lead citrate and uranyl acetate. This method could also be applied to the other small and thin samples such as the Drosophila embryo, ventral nerve cord and brain.
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12
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Xie J, Chen S, Bopassa JC, Banerjee S. Drosophila tubulin polymerization promoting protein mutants reveal pathological correlates relevant to human Parkinson's disease. Sci Rep 2021; 11:13614. [PMID: 34193896 PMCID: PMC8245532 DOI: 10.1038/s41598-021-92738-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 06/07/2021] [Indexed: 11/09/2022] Open
Abstract
Parkinson's disease (PD) is a progressive neurodegenerative disorder with no known cure. PD is characterized by locomotion deficits, nigrostriatal dopaminergic neuronal loss, mitochondrial dysfunctions and formation of α-Synuclein aggregates. A well-conserved and less understood family of Tubulin Polymerization Promoting Proteins (TPPP) is also implicated in PD and related disorders, where TPPP exists in pathological aggregates in neurons in patient brains. However, there are no in vivo studies on mammalian TPPP to understand the genetics and neuropathology linking TPPP aggregation or neurotoxicity to PD. Recently, we discovered the only Drosophila homolog of human TPPP named Ringmaker (Ringer). Here, we report that adult ringer mutants display progressive locomotor disabilities, reduced lifespan and neurodegeneration. Importantly, our findings reveal that Ringer is associated with mitochondria and ringer mutants have mitochondrial structural damage and dysfunctions. Adult ringer mutants also display progressive loss of dopaminergic neurons. Together, these phenotypes of ringer mutants recapitulate some of the salient features of human PD patients, thus allowing us to utilize ringer mutants as a fly model relevant to PD, and further explore its genetic and molecular underpinnings to gain insights into the role of human TPPP in PD.
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Affiliation(s)
- Jing Xie
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
- Xiangya School of Medicine, Central South University, Changsha, 410083, Hunan, China
| | - Shuting Chen
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
- Xiangya School of Medicine, Central South University, Changsha, 410083, Hunan, China
| | - Jean C Bopassa
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
| | - Swati Banerjee
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.
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13
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Aponte-Santiago NA, Littleton JT. Synaptic Properties and Plasticity Mechanisms of Invertebrate Tonic and Phasic Neurons. Front Physiol 2020; 11:611982. [PMID: 33391026 PMCID: PMC7772194 DOI: 10.3389/fphys.2020.611982] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022] Open
Abstract
Defining neuronal cell types and their associated biophysical and synaptic diversity has become an important goal in neuroscience as a mechanism to create comprehensive brain cell atlases in the post-genomic age. Beyond broad classification such as neurotransmitter expression, interneuron vs. pyramidal, sensory or motor, the field is still in the early stages of understanding closely related cell types. In both vertebrate and invertebrate nervous systems, one well-described distinction related to firing characteristics and synaptic release properties are tonic and phasic neuronal subtypes. In vertebrates, these classes were defined based on sustained firing responses during stimulation (tonic) vs. transient responses that rapidly adapt (phasic). In crustaceans, the distinction expanded to include synaptic release properties, with tonic motoneurons displaying sustained firing and weaker synapses that undergo short-term facilitation to maintain muscle contraction and posture. In contrast, phasic motoneurons with stronger synapses showed rapid depression and were recruited for short bursts during fast locomotion. Tonic and phasic motoneurons with similarities to those in crustaceans have been characterized in Drosophila, allowing the genetic toolkit associated with this model to be used for dissecting the unique properties and plasticity mechanisms for these neuronal subtypes. This review outlines general properties of invertebrate tonic and phasic motoneurons and highlights recent advances that characterize distinct synaptic and plasticity pathways associated with two closely related glutamatergic neuronal cell types that drive invertebrate locomotion.
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Affiliation(s)
- Nicole A. Aponte-Santiago
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - J. Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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14
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Kamimura K, Odajima A, Ikegawa Y, Maru C, Maeda N. The HSPG Glypican Regulates Experience-Dependent Synaptic and Behavioral Plasticity by Modulating the Non-Canonical BMP Pathway. Cell Rep 2020; 28:3144-3156.e4. [PMID: 31533037 DOI: 10.1016/j.celrep.2019.08.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/11/2019] [Accepted: 08/08/2019] [Indexed: 01/05/2023] Open
Abstract
Under food deprivation conditions, Drosophila larvae exhibit increases in locomotor speed and synaptic bouton numbers at neuromuscular junctions (NMJs). Octopamine, the invertebrate counterpart of noradrenaline, plays critical roles in this process; however, the underlying mechanisms remain unclear. We show here that a glypican (Dlp) negatively regulates type I synaptic bouton formation, postsynaptic expression of GluRIIA, and larval locomotor speed. Starvation-induced octopaminergic signaling decreases Dlp expression, leading to increases in synapse formation and locomotion. Dlp is expressed by postsynaptic muscle cells and suppresses the non-canonical BMP pathway, which is composed of the presynaptic BMP receptor Wit and postsynaptic GluRIIA-containing ionotropic glutamate receptor. We find that during starvation, decreases in Dlp increase non-canonical BMP signaling, leading to increases in GluRIIA expression, type I bouton number, and locomotor speed. Our results demonstrate that octopamine controls starvation-induced neural plasticity by regulating Dlp and provides insights into how proteoglycans can influence behavioral and synaptic plasticity.
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Affiliation(s)
- Keisuke Kamimura
- Neural Network Project, Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan.
| | - Aiko Odajima
- Neural Network Project, Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan
| | - Yuko Ikegawa
- Neural Network Project, Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan
| | - Chikako Maru
- Neural Network Project, Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan
| | - Nobuaki Maeda
- Neural Network Project, Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan.
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15
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Chou VT, Johnson SA, Van Vactor D. Synapse development and maturation at the drosophila neuromuscular junction. Neural Dev 2020; 15:11. [PMID: 32741370 PMCID: PMC7397595 DOI: 10.1186/s13064-020-00147-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
Synapses are the sites of neuron-to-neuron communication and form the basis of the neural circuits that underlie all animal cognition and behavior. Chemical synapses are specialized asymmetric junctions between a presynaptic neuron and a postsynaptic target that form through a series of diverse cellular and subcellular events under the control of complex signaling networks. Once established, the synapse facilitates neurotransmission by mediating the organization and fusion of synaptic vesicles and must also retain the ability to undergo plastic changes. In recent years, synaptic genes have been implicated in a wide array of neurodevelopmental disorders; the individual and societal burdens imposed by these disorders, as well as the lack of effective therapies, motivates continued work on fundamental synapse biology. The properties and functions of the nervous system are remarkably conserved across animal phyla, and many insights into the synapses of the vertebrate central nervous system have been derived from studies of invertebrate models. A prominent model synapse is the Drosophila melanogaster larval neuromuscular junction, which bears striking similarities to the glutamatergic synapses of the vertebrate brain and spine; further advantages include the simplicity and experimental versatility of the fly, as well as its century-long history as a model organism. Here, we survey findings on the major events in synaptogenesis, including target specification, morphogenesis, and the assembly and maturation of synaptic specializations, with a emphasis on work conducted at the Drosophila neuromuscular junction.
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Affiliation(s)
- Vivian T Chou
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Seth A Johnson
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
| | - David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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16
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Guangming G, Junhua G, Chenchen Z, Yang M, Wei X. Neurexin and Neuroligins Maintain the Balance of Ghost and Satellite Boutons at the Drosophila Neuromuscular Junction. Front Neuroanat 2020; 14:19. [PMID: 32581727 PMCID: PMC7296126 DOI: 10.3389/fnana.2020.00019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/26/2020] [Indexed: 11/22/2022] Open
Abstract
Neurexins and neuroligins are common synaptic adhesion molecules that are associated with autism and interact with each other in the synaptic cleft. The Drosophila neuromuscular junction (NMJ) bouton is a well-known model system in neuroscience, and ghost and satellite boutons, respectively, indicate the poor development and overgrowth of the NMJ boutons. However, the Drosophila neurexin (DNrx) and Drosophila neuroligins (DNlgs) are mainly observed in type Ib boutons, indicating the ultrastructural and developmental phenotypes of the Drosophila NMJ. Here, we identified the ultrastructural and developmental features of ghost and satellite boutons by utilizing dneurexin (dnrx) and dneuroligins (dnlgs) fly mutants and other associated fly strains. Ghost boutons contain synaptic vesicles with multiple diameters but very rarely contain T-bar structures and swollen or thin subsynaptic reticulum (SSR) membranes. The muscle cell membrane is invaginated at different sites, stretches to the ghost bouton from different directions, forms several layers that enwrap the ghost bouton, and then branches into the complex SSR. Satellite boutons share a common SSR membrane and present either a typical profile in which a main bouton is encircled by small boutons or two atypical profiles in which the small boutons are grouped together or distributed in beads without a main bouton. Electron and confocal microscopy data showed that dnrx, dnlg1, dnlg2, dnlg3, and dnlg4 mutations led to ghost boutons; the overexpression of dnrx, dnlg1, dnlg2, dnlg3, and dnlg4 led to satellite boutons; and the dnlg2;dnlg3 double mutation also led to satellite boutons. These results suggested that DNrx and DNlgs jointly maintain the development and function of NMJ boutons by regulating the balance of ghost and satellite boutons in Drosophila.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Geng Junhua
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Mou Yang
- School of Medicine, Southeast University, Nanjing, China
| | - Xie Wei
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China.,Institute of Life Sciences, The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
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17
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Luo F, Sclip A, Jiang M, Südhof TC. Neurexins cluster Ca 2+ channels within the presynaptic active zone. EMBO J 2020; 39:e103208. [PMID: 32134527 PMCID: PMC7110102 DOI: 10.15252/embj.2019103208] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 02/05/2023] Open
Abstract
To achieve ultrafast neurotransmission, neurons assemble synapses with highly organized presynaptic and postsynaptic nanomachines that are aligned by synaptic adhesion molecules. How functional assembly of presynaptic active zones is controlled via trans-synaptic interactions remains unknown. Here, we conditionally deleted all three neurexin adhesion molecules from presynaptic neurons of the calyx of Held in the mouse auditory system, a model synapse that allows precise biophysical analyses of synaptic properties. The pan-neurexin deletion had no effect on synapse development or the basic release machinery, but dramatically impaired fast neurotransmitter release. The overall properties of presynaptic calcium ion channels appeared normal, as reflected by the similar characteristics of calcium currents recorded at the nerve terminals. However, the pan-neurexin deletion significantly impaired the tight coupling of calcium influx to exocytosis, thereby suppressing neurotransmitter release. Furthermore, the pan-neurexin deletion reduced the function of calcium-activated BK potassium channels, whose activation depends on their tight association with presynaptic calcium channels. Together, these results suggest that neurexins perform a major function at the calyx synapse in coupling presynaptic calcium channels to release sites.
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Affiliation(s)
- Fujun Luo
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
| | - Alessandra Sclip
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
| | - Man Jiang
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
| | - Thomas C Südhof
- Department of Molecular and Cellular PhysiologyHoward Hughes Medical InstituteStanford University Medical SchoolStanfordCAUSA
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18
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Berke B, Le L, Keshishian H. Target-dependent retrograde signaling mediates synaptic plasticity at the Drosophila neuromuscular junction. Dev Neurobiol 2020; 79:895-912. [PMID: 31950660 DOI: 10.1002/dneu.22731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 12/26/2022]
Abstract
Neurons that innervate multiple targets often establish synapses with target-specific strengths, and local forms of synaptic plasticity. We have examined the molecular-genetic mechanisms that allow a single Drosophila motoneuron, the ventral Common Exciter (vCE), to establish connections with target-specific properties at its various synaptic partners. By driving transgenes in a subset of vCE's targets, we found that individual target cells are able to independently control the properties of vCE's innervating branch and synapses. This is achieved by means of a trans-synaptic growth factor secreted by the target cell. At the larval neuromuscular junction, postsynaptic glutamate receptor activity stimulates the release of the BMP4/5/6 homolog Glass bottom boat (Gbb). As larvae mature and motoneuron terminals grow, Gbb activates the R-Smad transcriptional regulator phosphorylated Mad (pMad) to facilitate presynaptic development. We found that manipulations affecting glutamate receptors or Gbb within subsets of target muscles led to local effects either specific to the manipulated muscle or by a limited gradient within the presynaptic branches. While presynaptic development depends on pMad transcriptional activity within the motoneuron nucleus, we find that the Gbb growth factor may also act locally within presynaptic terminals. Local Gbb signaling and presynaptic pMad accumulation within boutons may therefore participate in a "synaptic tagging" mechanism, to influence synaptic growth and plasticity in Drosophila.
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Affiliation(s)
- Brett Berke
- Molecular, Cellular, and Developmental Biology Department, Yale University, New Haven, CT, USA
| | - Linh Le
- University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Haig Keshishian
- Molecular, Cellular, and Developmental Biology Department, Yale University, New Haven, CT, USA
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19
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Vargas EJM, Matamoros AJ, Qiu J, Jan CH, Wang Q, Gorczyca D, Han TW, Weissman JS, Jan YN, Banerjee S, Song Y. The microtubule regulator ringer functions downstream from the RNA repair/splicing pathway to promote axon regeneration. Genes Dev 2020; 34:194-208. [PMID: 31919191 PMCID: PMC7000917 DOI: 10.1101/gad.331330.119] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/10/2019] [Indexed: 12/17/2022]
Abstract
In this study, Vargas et al. set out to elucidate the downstream effectors of the Rtca-mediated RNA repair/splicing pathway. Using genome-wide transcriptome analysis, the authors demonstrate that the microtubule-associated protein (MAP) tubulin polymerization-promoting protein (TPPP) ringer functions downstream from and is suppressed by Rtca via Xbp1-dependent transcription. Ringer cell-autonomously promotes axon regeneration in the peripheral and central nervous system. Promoting axon regeneration in the central and peripheral nervous system is of clinical importance in neural injury and neurodegenerative diseases. Both pro- and antiregeneration factors are being identified. We previously reported that the Rtca mediated RNA repair/splicing pathway restricts axon regeneration by inhibiting the nonconventional splicing of Xbp1 mRNA under cellular stress. However, the downstream effectors remain unknown. Here, through transcriptome profiling, we show that the tubulin polymerization-promoting protein (TPPP) ringmaker/ringer is dramatically increased in Rtca-deficient Drosophila sensory neurons, which is dependent on Xbp1. Ringer is expressed in sensory neurons before and after injury, and is cell-autonomously required for axon regeneration. While loss of ringer abolishes the regeneration enhancement in Rtca mutants, its overexpression is sufficient to promote regeneration both in the peripheral and central nervous system. Ringer maintains microtubule stability/dynamics with the microtubule-associated protein futsch/MAP1B, which is also required for axon regeneration. Furthermore, ringer lies downstream from and is negatively regulated by the microtubule-associated deacetylase HDAC6, which functions as a regeneration inhibitor. Taken together, our findings suggest that ringer acts as a hub for microtubule regulators that relays cellular status information, such as cellular stress, to the integrity of microtubules in order to instruct neuroregeneration.
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Affiliation(s)
- Ernest J Monahan Vargas
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Andrew J Matamoros
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jingyun Qiu
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Calvin H Jan
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94158, USA.,Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA
| | - Qin Wang
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - David Gorczyca
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Tina W Han
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94158, USA.,Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Swati Banerjee
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health Science Center, San Antonio, Texas 78229, USA
| | - Yuanquan Song
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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20
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Waddell EA, Viveiros JM, Robinson EL, Sharoni MA, Latcheva NK, Marenda DR. Extramacrochaetae promotes branch and bouton number via the sequestration of daughterless in the cytoplasm of neurons. Dev Neurobiol 2019; 79:805-818. [PMID: 31581354 DOI: 10.1002/dneu.22720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/18/2019] [Accepted: 09/28/2019] [Indexed: 11/09/2022]
Abstract
The Class I basic helix-loop-helix (bHLH) proteins are highly conserved transcription factors that are ubiquitously expressed. A wealth of literature on Class I bHLH proteins has shown that these proteins must homodimerize or heterodimerize with tissue-specific HLH proteins in order to bind DNA at E-box consensus sequences to control tissue-specific transcription. Due to its ubiquitous expression, Class I bHLH proteins are also extensively regulated posttranslationally, mostly through dimerization. Previously, we reported that in addition to its role in promoting neurogenesis, the Class I bHLH protein daughterless also functions in mature neurons to restrict axon branching and synapse number. Here, we show that part of the molecular logic that specifies how daughterless functions in neurogenesis is also conserved in neurons. We show that the Type V HLH protein extramacrochaetae (Emc) binds to and represses daughterless function by sequestering daughterless to the cytoplasm. This work provides initial insights into the mechanisms underlying the function of daughterless and Emc in neurons while providing a novel understanding of how Emc functions to restrict daughterless activity within the cell.
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Affiliation(s)
- Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | | | - Erin L Robinson
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Michal A Sharoni
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Nina K Latcheva
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Daniel R Marenda
- Department of Biology, Drexel University, Philadelphia, Pennsylvania.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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21
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Bellosta P, Soldano A. Dissecting the Genetics of Autism Spectrum Disorders: A Drosophila Perspective. Front Physiol 2019; 10:987. [PMID: 31481894 PMCID: PMC6709880 DOI: 10.3389/fphys.2019.00987] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 07/18/2019] [Indexed: 01/10/2023] Open
Abstract
Autism Spectrum Disorder (ASD) is a complex group of multi-factorial developmental disorders that leads to communication and behavioral defects. Genetic alterations have been identified in around 20% of ASD patients and the use of genetic models, such as Drosophila melanogaster, has been of paramount importance in deciphering the significance of these alterations. In fact, many of the ASD associated genes, such as FMR1, Neurexin, Neuroligins and SHANK encode for proteins that have conserved functions in neurons and during synapse development, both in humans and in the fruit fly. Drosophila is a prominent model in neuroscience due to the conserved genetic networks that control neurodevelopmental processes and to the ease of manipulating its genetics. In the present review we will describe recent advances in the field of ASD with a particular focus on the characterization of genes where the use of Drosophila has been fundamental to better understand their function.
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Affiliation(s)
- Paola Bellosta
- Laboratory of Metabolism of Cell Growth and Neuronal Survival, Department of Cellular, Computational and Integrative Biology (CIBio), University of Trento, Trento, Italy.,Department of Medicine, New York University Langone Medical Center, New York, NY, United States
| | - Alessia Soldano
- Laboratory of Translational Genomics, Department of Cellular, Computational and Integrative Biology (CIBio), University of Trento, Trento, Italy
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22
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Shi Q, Lin YQ, Saliba A, Xie J, Neely GG, Banerjee S. Tubulin Polymerization Promoting Protein, Ringmaker, and MAP1B Homolog Futsch Coordinate Microtubule Organization and Synaptic Growth. Front Cell Neurosci 2019; 13:192. [PMID: 31156389 PMCID: PMC6529516 DOI: 10.3389/fncel.2019.00192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 04/16/2019] [Indexed: 12/15/2022] Open
Abstract
Drosophila Ringmaker (Ringer) is homologous to the human Tubulin Polymerization Promoting Proteins (TPPPs) that are implicated in the stabilization and bundling of microtubules (MTs) that are particularly important for neurons and are also implicated in synaptic organization and plasticity. No in vivo functional data exist that have addressed the role of TPPP in synapse organization in any system. Here, we present the phenotypic and functional characterization of ringer mutants during Drosophila larval neuromuscular junction (NMJ) synaptic development. ringer mutants show reduced synaptic growth and transmission and display phenotypic similarities and genetic interactions with the Drosophila homolog of vertebrate Microtubule Associated Protein (MAP)1B, futsch. Immunohistochemical and biochemical analyses show that individual and combined loss of Ringer and Futsch cause a significant reduction in MT loops at the NMJs and reduced acetylated-tubulin levels. Presynaptic over-expression of Ringer and Futsch causes elevated levels of acetylated-tubulin and significant increase in NMJ MT loops. These results indicate that Ringer and Futsch regulate synaptic MT organization in addition to synaptic growth. Together our findings may inform studies on the close mammalian homolog, TPPP, and provide insights into the role of MTs and associated proteins in synapse growth and organization.
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Affiliation(s)
- Qian Shi
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, San Antonio, TX, United States
| | - Yong Qi Lin
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Afaf Saliba
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, San Antonio, TX, United States
| | - Jing Xie
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, San Antonio, TX, United States
- Xiangya School of Medicine, Central South University, Changsha, China
| | - G. Gregory Neely
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Swati Banerjee
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, San Antonio, TX, United States
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23
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Han KA, Um JW, Ko J. Intracellular protein complexes involved in synapse assembly in presynaptic neurons. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 116:347-373. [PMID: 31036296 DOI: 10.1016/bs.apcsb.2018.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The presynaptic active zone, composed of evolutionarily conserved protein complexes, is a specialized area that serves to orchestrate precise and efficient neurotransmitter release by organizing various presynaptic proteins involved in mediating docking and priming of synaptic vesicles, recruiting voltage-gated calcium channels, and modulating presynaptic nerve terminals with aligned postsynaptic structures. Among membrane proteins localized to active zone, presynaptic neurexins and LAR-RPTPs (leukocyte common antigen-related receptor tyrosine phosphatase) have emerged as hubs that orchestrate both shared and distinct extracellular synaptic adhesion pathways. In this chapter, we discuss intracellular signaling cascades involved in recruiting various intracellular proteins at both excitatory and inhibitory synaptic sites. In particular, we highlight recent studies on key active zone proteins that physically and functionally link these cascades with neurexins and LAR-RPTPs in both vertebrate and invertebrate model systems. These studies allow us to build a general, universal view of how presynaptic active zones operate together with postsynaptic structures in neural circuits.
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Affiliation(s)
- Kyung Ah Han
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea.
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24
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Banerjee S, Riordan M. Coordinated Regulation of Axonal Microtubule Organization and Transport by Drosophila Neurexin and BMP Pathway. Sci Rep 2018; 8:17337. [PMID: 30478335 PMCID: PMC6255869 DOI: 10.1038/s41598-018-35618-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/07/2018] [Indexed: 01/23/2023] Open
Abstract
Neurexins are well known trans-synaptic cell adhesion molecules that are required for proper synaptic development and function across species. Beyond synapse organization and function, little is known about other roles Neurexins might have in the nervous system. Here we report novel phenotypic consequences of mutations in Drosophila neurexin (dnrx), which alters axonal microtubule organization and transport. We show that dnrx mutants display phenotypic similarities with the BMP receptor wishful thinking (wit) and one of the downstream effectors, futsch, which is a known regulator of microtubule organization and stability. dnrx has genetic interactions with wit and futsch. Loss of Dnrx also results in reduced levels of other downstream effectors of BMP signaling, phosphorylated-Mad and Trio. Interestingly, postsynaptic overexpression of the BMP ligand, Glass bottom boat, in dnrx mutants partially rescues the axonal transport defects but not the synapse undergrowth at the neuromuscular junctions. These data suggest that Dnrx and BMP signaling are involved in many diverse functions and that regulation of axonal MT organization and transport might be distinct from regulation of synaptic growth in dnrx mutants. Together, our work uncovers a novel function of Drosophila Neurexin and may provide insights into functions of Neurexins in vertebrates.
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Affiliation(s)
- Swati Banerjee
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.
| | - Maeveen Riordan
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.,University of Colorado School of Medicine, 12631 E. 17th Avenue B177, Aurora, CO, 80045, USA
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25
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Harris KP, Littleton JT, Stewart BA. Postsynaptic Syntaxin 4 negatively regulates the efficiency of neurotransmitter release. J Neurogenet 2018; 32:221-229. [PMID: 30175640 PMCID: PMC6317344 DOI: 10.1080/01677063.2018.1501372] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/13/2018] [Indexed: 12/12/2022]
Abstract
Signaling from the postsynaptic compartment regulates multiple aspects of synaptic development and function. Syntaxin 4 (Syx4) is a plasma membrane t-SNARE that promotes the growth and plasticity of Drosophila neuromuscular junctions (NMJs) by regulating the localization of key synaptic proteins in the postsynaptic compartment. Here, we describe electrophysiological analyses and report that loss of Syx4 leads to enhanced neurotransmitter release, despite a decrease in the number of active zones. We describe a requirement for postsynaptic Syx4 in regulating several presynaptic parameters, including Ca2+ cooperativity and the abundance of the presynaptic calcium channel Cacophony (Cac) at active zones. These findings indicate Syx4 negatively regulates presynaptic neurotransmitter release through a retrograde signaling mechanism from the postsynaptic compartment.
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Affiliation(s)
- Kathryn P Harris
- a Department of Biology , University of Toronto Mississauga , Mississauga , ON, Canada
- b Department of Cell and Systems Biology , University of Toronto , Toronto , ON, Canada
| | - J Troy Littleton
- c The Picower Institute for Learning and Memory , Massachusetts Institute of Technology , Cambridge , MA , USA
- d Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
- e Department of Brain and Cognitive Sciences , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Bryan A Stewart
- a Department of Biology , University of Toronto Mississauga , Mississauga , ON, Canada
- b Department of Cell and Systems Biology , University of Toronto , Toronto , ON, Canada
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26
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Philbrook A, Ramachandran S, Lambert CM, Oliver D, Florman J, Alkema MJ, Lemons M, Francis MM. Neurexin directs partner-specific synaptic connectivity in C. elegans. eLife 2018; 7:35692. [PMID: 30039797 PMCID: PMC6057746 DOI: 10.7554/elife.35692] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 06/21/2018] [Indexed: 01/14/2023] Open
Abstract
In neural circuits, individual neurons often make projections onto multiple postsynaptic partners. Here, we investigate molecular mechanisms by which these divergent connections are generated, using dyadic synapses in C. elegans as a model. We report that C. elegans nrx-1/neurexin directs divergent connectivity through differential actions at synapses with partnering neurons and muscles. We show that cholinergic outputs onto neurons are, unexpectedly, located at previously undefined spine-like protrusions from GABAergic dendrites. Both these spine-like features and cholinergic receptor clustering are strikingly disrupted in the absence of nrx-1. Excitatory transmission onto GABAergic neurons, but not neuromuscular transmission, is also disrupted. Our data indicate that NRX-1 located at presynaptic sites specifically directs postsynaptic development in GABAergic neurons. Our findings provide evidence that individual neurons can direct differential patterns of connectivity with their post-synaptic partners through partner-specific utilization of synaptic organizers, offering a novel view into molecular control of divergent connectivity. Nervous systems are complex networks of interconnected cells called neurons. These networks vary in size from a few hundred cells in worms, to tens of billions in the human brain. Within these networks, each individual neuron forms connections – called synapses – with many others. But these partner neurons are not necessarily alike. In fact, they may be different cell types. How neurons form distinct connections with different partner cells remains unclear. Part of the answer may lie in specialized proteins called cell adhesion molecules. These proteins occur on the cell surface and enable neurons to recognize one another. This helps ensure that the cells form appropriate connections via synapses. Cell adhesion molecules are therefore also known as synaptic organizers. Philbrook et al. have now examined the role of synaptic organizers in wiring up the nervous system of the nematode worm and model organism Caenorhabditis elegans. Motor neurons form connections with two types of partner cell: muscle cells and neurons. Philbrook et al. screened C. elegans that have mutations in genes encoding various synaptic organizers. This revealed that a protein called neurexin must be present for motor neurons to form synapses with other neurons. By contrast, neurexin is not required for the same neurons to establish synapses with muscles. Philbrook et al. found that neuron-to-neuron synapses arise at specialized finger-like projections. These resemble the dendritic spines at which synapses form in the brains of mammals, and had not been previously identified in C. elegans. In worms that lack neurexin, these spine-like structures do not form correctly, disrupting the formation of neuron-to-neuron connections. Previous work has implicated neurexin in synapse formation in the mammalian brain. But this is the first study to reveal a role for neurexin in establishing partner-specific synaptic connections. Mutations in synaptic organizers, including neurexin, contribute to disorders of brain development. These include schizophrenia and autism spectrum disorders. Learning more about how neurexin helps establish specific synaptic connections may help us understand how these disorders arise.
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Affiliation(s)
- Alison Philbrook
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Shankar Ramachandran
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Christopher M Lambert
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Devyn Oliver
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Jeremy Florman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Mark J Alkema
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Michele Lemons
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States.,Department of Natural Sciences, Assumption College, Worcester, United States
| | - Michael M Francis
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
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27
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Xing G, Li M, Sun Y, Rui M, Zhuang Y, Lv H, Han J, Jia Z, Xie W. Neurexin-Neuroligin 1 regulates synaptic morphology and functions via the WAVE regulatory complex in Drosophila neuromuscular junction. eLife 2018. [PMID: 29537369 PMCID: PMC5873926 DOI: 10.7554/elife.30457] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Neuroligins are postsynaptic adhesion molecules that are essential for postsynaptic specialization and synaptic function. But the underlying molecular mechanisms of neuroligin functions remain unclear. We found that Drosophila Neuroligin 1 (DNlg1) regulates synaptic structure and function through WAVE regulatory complex (WRC)-mediated postsynaptic actin reorganization. The disruption of DNlg1, DNlg2, or their presynaptic partner neurexin (DNrx) led to a dramatic decrease in the amount of F-actin. Further study showed that DNlg1, but not DNlg2 or DNlg3, directly interacts with the WRC via its C-terminal interacting receptor sequence. That interaction is required to recruit WRC to the postsynaptic membrane to promote F-actin assembly. Furthermore, the interaction between DNlg1 and the WRC is essential for DNlg1 to rescue the morphological and electrophysiological defects in dnlg1 mutants. Our results reveal a novel mechanism by which the DNrx-DNlg1 trans-synaptic interaction coordinates structural and functional properties at the neuromuscular junction.
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Affiliation(s)
- Guanglin Xing
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
| | - Moyi Li
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yichen Sun
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
| | - Menglong Rui
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
| | - Yan Zhuang
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
| | - Huihui Lv
- The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China
| | - Junhai Han
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Zhengping Jia
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China.,Neurosciences and Mental Health Program, The Hospital for Sick Children, University of Toronto, Ontario, Canada
| | - Wei Xie
- Institute of Life Sciences, the Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
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28
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Pandey H, Bourahmoune K, Honda T, Honjo K, Kurita K, Sato T, Sawa A, Furukubo-Tokunaga K. Genetic interaction of DISC1 and Neurexin in the development of fruit fly glutamatergic synapses. NPJ SCHIZOPHRENIA 2017; 3:39. [PMID: 29079805 PMCID: PMC5660244 DOI: 10.1038/s41537-017-0040-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 09/19/2017] [Accepted: 09/27/2017] [Indexed: 12/31/2022]
Abstract
Originally identified at the breakpoint of a (1;11)(q42.1; q14.3) chromosomal translocation in a Scottish family with a wide range of mental disorders, the DISC1 gene has been a focus of intensive investigations as an entry point to study the molecular mechanisms of diverse mental dysfunctions. Perturbations of the DISC1 functions lead to behavioral changes in animal models, which are relevant to psychiatric conditions in patients. In this work, we have expressed the human DISC1 gene in the fruit fly (Drosophila melanogaster) and performed a genetic screening for the mutations of psychiatric risk genes that cause modifications of DISC1 synaptic phenotypes at the neuromuscular junction. We found that DISC1 interacts with dnrx1, the Drosophila homolog of the human Neurexin (NRXN1) gene, in the development of glutamatergic synapses. While overexpression of DISC1 suppressed the total bouton area on the target muscles and stimulated active zone density in wild-type background, a partial reduction of the dnrx1 activity negated the DISC1–mediated synaptic alterations. Likewise, overexpression of DISC1 stimulated the expression of a glutamate receptor component, DGLURIIA, in wild-type background but not in the dnrx1 heterozygous background. In addition, DISC1 caused mislocalization of Discs large, the Drosophila PSD-95 homolog, in the dnrx1 heterozygous background. Analyses with a series of domain deletions have revealed the importance of axonal localization of the DISC1 protein for efficient suppression of DNRX1 in synaptic boutons. These results thus suggest an intriguing converging mechanism controlled by the interaction of DISC1 and Neurexin in the developing glutamatergic synapses. Fruit fly models uncover a potential new mechanism by which two schizophrenia risk factor genes interact to alter synaptic junctions. DISC1 gene alterations have previously been linked to psychiatric anomalies, although the gene has not been formally recognized as a schizophrenia risk factor. A US-Japan research collaboration led by the University of Tsukuba’s Katsuo Furukubo-Tokunaga expressed human DISC1 in fruit fly synapses to better understand the changes that take place when gene disruption leads to overexpression. The team found that overexpression of DISC1 affected the expression of the fruit fly counterpart to human ‘neurexin,’ a known risk factor for conditions including schizophrenia and autism spectrum disorders. The interaction between neurexin and DISC1 also influenced other synapse-altering genes. Further research is warranted to explore the roles of DISC1 and neurexin in psychiatric disease.
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Affiliation(s)
- Himani Pandey
- Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Katia Bourahmoune
- Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Takato Honda
- Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Ken Honjo
- Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Kazuki Kurita
- Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Tomohito Sato
- Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Akira Sawa
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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29
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Jordán-Álvarez S, Santana E, Casas-Tintó S, Acebes Á, Ferrús A. The equilibrium between antagonistic signaling pathways determines the number of synapses in Drosophila. PLoS One 2017; 12:e0184238. [PMID: 28892511 PMCID: PMC5593197 DOI: 10.1371/journal.pone.0184238] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/21/2017] [Indexed: 12/12/2022] Open
Abstract
The number of synapses is a major determinant of behavior and many neural diseases exhibit deviations in that number. However, how signaling pathways control this number is still poorly understood. Using the Drosophila larval neuromuscular junction, we show here a PI3K-dependent pathway for synaptogenesis which is functionally connected with other previously known elements including the Wit receptor, its ligand Gbb, and the MAPkinases cascade. Based on epistasis assays, we determined the functional hierarchy within the pathway. Wit seems to trigger signaling through PI3K, and Ras85D also contributes to the initiation of synaptogenesis. However, contrary to other signaling pathways, PI3K does not require Ras85D binding in the context of synaptogenesis. In addition to the MAPK cascade, Bsk/JNK undergoes regulation by Puc and Ras85D which results in a narrow range of activity of this kinase to determine normalcy of synapse number. The transcriptional readout of the synaptogenesis pathway involves the Fos/Jun complex and the repressor Cic. In addition, we identified an antagonistic pathway that uses the transcription factors Mad and Medea and the microRNA bantam to down-regulate key elements of the pro-synaptogenesis pathway. Like its counterpart, the anti-synaptogenesis signaling uses small GTPases and MAPKs including Ras64B, Ras-like-a, p38a and Licorne. Bantam downregulates the pro-synaptogenesis factors PI3K, Hiw, Ras85D and Bsk, but not AKT. AKT, however, can suppress Mad which, in conjunction with the reported suppression of Mad by Hiw, closes the mutual regulation between both pathways. Thus, the number of synapses seems to result from the balanced output from these two pathways.
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Affiliation(s)
| | | | | | - Ángel Acebes
- Institute Cajal C.S.I.C., Madrid, Spain
- * E-mail: (AF); (AA)
| | - Alberto Ferrús
- Institute Cajal C.S.I.C., Madrid, Spain
- * E-mail: (AF); (AA)
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30
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Petralia RS, Wang YX, Mattson MP, Yao PJ. Invaginating Presynaptic Terminals in Neuromuscular Junctions, Photoreceptor Terminals, and Other Synapses of Animals. Neuromolecular Med 2017; 19:193-240. [PMID: 28612182 PMCID: PMC6518423 DOI: 10.1007/s12017-017-8445-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/01/2017] [Indexed: 10/19/2022]
Abstract
Typically, presynaptic terminals form a synapse directly on the surface of postsynaptic processes such as dendrite shafts and spines. However, some presynaptic terminals invaginate-entirely or partially-into postsynaptic processes. We survey these invaginating presynaptic terminals in all animals and describe several examples from the central nervous system, including giant fiber systems in invertebrates, and cup-shaped spines, electroreceptor synapses, and some specialized auditory and vestibular nerve terminals in vertebrates. We then examine mechanoreceptors and photoreceptors, concentrating on the complex of pre- and postsynaptic processes found in basal invaginations of the cell. We discuss in detail the role of vertebrate invaginating horizontal cell processes in both chemical and electrical feedback mechanisms. We also discuss the common presence of indenting or invaginating terminals in neuromuscular junctions on muscles of most kinds of animals, and especially discuss those of Drosophila and vertebrates. Finally, we consider broad questions about the advantages of possessing invaginating presynaptic terminals and describe some effects of aging and disease, especially on neuromuscular junctions. We suggest that the invagination is a mechanism that can enhance both chemical and electrical interactions at the synapse.
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Affiliation(s)
- Ronald S Petralia
- Advanced Imaging Core, NIDCD/NIH, 35A Center Drive, Room 1E614, Bethesda, MD, 20892-3729, USA.
| | - Ya-Xian Wang
- Advanced Imaging Core, NIDCD/NIH, 35A Center Drive, Room 1E614, Bethesda, MD, 20892-3729, USA
| | - Mark P Mattson
- Laboratory of Neurosciences, NIA/NIH, Baltimore, MD, 21224, USA
| | - Pamela J Yao
- Laboratory of Neurosciences, NIA/NIH, Baltimore, MD, 21224, USA
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Saifetiarova J, Liu X, Taylor AM, Li J, Bhat MA. Axonal domain disorganization in Caspr1 and Caspr2 mutant myelinated axons affects neuromuscular junction integrity, leading to muscle atrophy. J Neurosci Res 2017; 95:1373-1390. [PMID: 28370195 DOI: 10.1002/jnr.24052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 02/14/2017] [Accepted: 02/24/2017] [Indexed: 12/19/2022]
Abstract
Bidirectional interactions between neurons and myelinating glial cells result in formation of axonal domains along myelinated fibers. Loss of axonal domains leads to detrimental consequences on nerve structure and function, resulting in reduced conductive properties and the diminished ability to reliably transmit signals to the targets they innervate. Thus, impairment of peripheral myelinated axons that project to the surface of muscle fibers and form neuromuscular junction (NMJ) synapses leads to muscle dysfunction. The goal of our studies was to determine how altered electrophysiological properties due to axonal domain disorganization lead to muscle pathology, which is relevant to a variety of peripheral neuropathies, demyelinating diseases, and neurodegenerative disorders. Using conventional Contactin-Associated Protein 1 (Caspr1) and Caspr2 single or double mutants with disrupted paranodal, juxtaparanodal, or both regions, respectively, in peripheral myelinated axons, we correlated defects in NMJ integrity and muscle pathology. Our data show that loss of axonal domains in Caspr1 and Caspr2 single and double mutants primarily alters distal myelinated fibers together with presynaptic terminals, eventually leading to NMJ denervation and reduction in postsynaptic endplate areas. Moreover, reduction in conductive properties of peripheral myelinated fibers together with NMJ disintegration leads to muscle atrophy in Caspr1 mutants or muscle fiber degeneration accompanied by mitochondrial dysfunction in Caspr1/Caspr2 double mutants. Together, our data indicate that proper organization of axonal domains in myelinated fibers is critical for optimal propagation of electrical signals, NMJ integrity, and muscle health, and provide insights into a wide range of pathologies that result in reduced nerve conduction leading to muscle atrophy. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Julia Saifetiarova
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Xi Liu
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Anna M Taylor
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Jie Li
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
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Park SM, Park HR, Lee JH. MAPK3 at the Autism-Linked Human 16p11.2 Locus Influences Precise Synaptic Target Selection at Drosophila Larval Neuromuscular Junctions. Mol Cells 2017; 40:151-161. [PMID: 28196412 PMCID: PMC5339506 DOI: 10.14348/molcells.2017.2307] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/22/2017] [Accepted: 01/23/2017] [Indexed: 01/10/2023] Open
Abstract
Proper synaptic function in neural circuits requires precise pairings between correct pre- and post-synaptic partners. Errors in this process may underlie development of neuropsychiatric disorders, such as autism spectrum disorder (ASD). Development of ASD can be influenced by genetic factors, including copy number variations (CNVs). In this study, we focused on a CNV occurring at the 16p11.2 locus in the human genome and investigated potential defects in synaptic connectivity caused by reduced activities of genes located in this region at Drosophila larval neuromuscular junctions, a well-established model synapse with stereotypic synaptic structures. A mutation of rolled, a Drosophila homolog of human mitogen-activated protein kinase 3 (MAPK3) at the 16p11.2 locus, caused ectopic innervation of axonal branches and their abnormal defasciculation. The specificity of these phenotypes was confirmed by expression of wild-type rolled in the mutant background. Albeit to a lesser extent, we also observed ectopic innervation patterns in mutants defective in Cdk2, Gαq, and Gp93, all of which were expected to interact with Rolled MAPK3. A further genetic analysis in double heterozygous combinations revealed a synergistic interaction between rolled and Gp93. In addition, results from RT-qPCR analyses indicated consistently reduced rolled mRNA levels in Cdk2, Gαq, and Gp93 mutants. Taken together, these data suggest a central role of MAPK3 in regulating the precise targeting of presynaptic axons to proper postsynaptic targets, a critical step that may be altered significantly in ASD.
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Affiliation(s)
- Sang Mee Park
- Department of Oral Pathology and BK21Plus Project, School of Dentistry, Pusan National University, Yangsan 50612,
Korea
| | - Hae Ryoun Park
- Department of Oral Pathology and BK21Plus Project, School of Dentistry, Pusan National University, Yangsan 50612,
Korea
- Institute of Translational Dental Sciences, Pusan National University, Yangsan 50612,
Korea
| | - Ji Hye Lee
- Department of Oral Pathology and BK21Plus Project, School of Dentistry, Pusan National University, Yangsan 50612,
Korea
- Institute of Translational Dental Sciences, Pusan National University, Yangsan 50612,
Korea
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