1
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Xu C, Li Z, Lyu C, Hu Y, McLaughlin CN, Wong KKL, Xie Q, Luginbuhl DJ, Li H, Udeshi ND, Svinkina T, Mani DR, Han S, Li T, Li Y, Guajardo R, Ting AY, Carr SA, Li J, Luo L. Molecular and cellular mechanisms of teneurin signaling in synaptic partner matching. Cell 2024; 187:5081-5101.e19. [PMID: 38996528 DOI: 10.1016/j.cell.2024.06.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 05/20/2024] [Accepted: 06/18/2024] [Indexed: 07/14/2024]
Abstract
In developing brains, axons exhibit remarkable precision in selecting synaptic partners among many non-partner cells. Evolutionarily conserved teneurins are transmembrane proteins that instruct synaptic partner matching. However, how intracellular signaling pathways execute teneurins' functions is unclear. Here, we use in situ proximity labeling to obtain the intracellular interactome of a teneurin (Ten-m) in the Drosophila brain. Genetic interaction studies using quantitative partner matching assays in both olfactory receptor neurons (ORNs) and projection neurons (PNs) reveal a common pathway: Ten-m binds to and negatively regulates a RhoGAP, thus activating the Rac1 small GTPases to promote synaptic partner matching. Developmental analyses with single-axon resolution identify the cellular mechanism of synaptic partner matching: Ten-m signaling promotes local F-actin levels and stabilizes ORN axon branches that contact partner PN dendrites. Combining spatial proteomics and high-resolution phenotypic analyses, this study advanced our understanding of both cellular and molecular mechanisms of synaptic partner matching.
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Affiliation(s)
- Chuanyun Xu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Biology Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Zhuoran Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Biology Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Cheng Lyu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Yixin Hu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Biology Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Colleen N McLaughlin
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Kenneth Kin Lam Wong
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Hongjie Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Namrata D Udeshi
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Tanya Svinkina
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - D R Mani
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Shuo Han
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Tongchao Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Yang Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Biology Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Ricardo Guajardo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Biology Graduate Program, Stanford University, Stanford, CA 94305, USA; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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2
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Chitre K, Kairamkonda S, Dwivedi MK, Yadav S, Kumar V, Sikdar SK, Nongthomba U. Beadex, the Drosophila LIM only protein, is required for the growth of the larval neuromuscular junction. J Neurophysiol 2024; 132:418-432. [PMID: 38838299 DOI: 10.1152/jn.00064.2024] [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: 02/12/2024] [Revised: 05/31/2024] [Accepted: 06/05/2024] [Indexed: 06/07/2024] Open
Abstract
The appropriate growth of the neurons, accurate organization of their synapses, and successful neurotransmission are indispensable for sensorimotor activities. These processes are highly dynamic and tightly regulated. Extensive genetic, molecular, physiological, and behavioral studies have identified many molecular candidates and investigated their roles in various neuromuscular processes. In this article, we show that Beadex (Bx), the Drosophila LIM only (LMO) protein, is required for motor activities and neuromuscular growth of Drosophila. The larvae bearing Bx7, a null allele of Bx, and the RNAi-mediated neuronal-specific knockdown of Bx show drastically reduced crawling behavior, a diminished synaptic span of the neuromuscular junctions (NMJs) and an increased spontaneous neuronal firing with altered motor patterns in the central pattern generators (CPGs). Microarray studies identified multiple targets of Beadex that are involved in different cellular and molecular pathways, including those associated with the cytoskeleton and mitochondria that could be responsible for the observed neuromuscular defects. With genetic interaction studies, we further show that Highwire (Hiw), a negative regulator of synaptic growth at the NMJs, negatively regulates Bx, as the latter's deficiency was able to rescue the phenotype of the Hiw null mutant, HiwDN. Thus, our data indicate that Beadex functions downstream of Hiw to regulate the larval synaptic growth and physiology.NEW & NOTEWORTHY A novel role for Beadex (Bx) regulates the larval neuromuscular junction (NMJ) structure and function in a tissue-specific manner. Bx is expressed in a subset of Toll-6-expressing neurons and is involved in regulating synaptic span and physiology, possibly through its negative interaction with Highwire (Hiw). The findings of this study provide insights into the molecular mechanisms underlying NMJ development and function and warrant further investigation to understand the role of Bx in these processes fully.
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Affiliation(s)
- Kripa Chitre
- Department of Development Biology and Genetics (DBG), Indian Institute of Science (IISc), Bangalore, India
| | - Subhash Kairamkonda
- Department of Development Biology and Genetics (DBG), Indian Institute of Science (IISc), Bangalore, India
| | - Manish Kumar Dwivedi
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Saumitra Yadav
- Molecular Biophysics Unit (MBU), Indian Institute of Science (IISc), Bangalore, India
| | - Vimlesh Kumar
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Sujit K Sikdar
- Molecular Biophysics Unit (MBU), Indian Institute of Science (IISc), Bangalore, India
| | - Upendra Nongthomba
- Department of Development Biology and Genetics (DBG), Indian Institute of Science (IISc), Bangalore, India
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3
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McDonald NA, Tao L, Dong MQ, Shen K. SAD-1 kinase controls presynaptic phase separation by relieving SYD-2/Liprin-α autoinhibition. PLoS Biol 2023; 21:e3002421. [PMID: 38048304 PMCID: PMC10695385 DOI: 10.1371/journal.pbio.3002421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 11/06/2023] [Indexed: 12/06/2023] Open
Abstract
Neuronal development orchestrates the formation of an enormous number of synapses that connect the nervous system. In developing presynapses, the core active zone structure has been found to assemble through liquid-liquid phase separation. Here, we find that the phase separation of Caenorhabditis elegans SYD-2/Liprin-α, a key active zone scaffold, is controlled by phosphorylation. We identify the SAD-1 kinase as a regulator of SYD-2 phase separation and determine presynaptic assembly is impaired in sad-1 mutants and increased by overactivation of SAD-1. Using phosphoproteomics, we find SAD-1 phosphorylates SYD-2 on 3 sites that are critical to activate phase separation. Mechanistically, SAD-1 phosphorylation relieves a binding interaction between 2 folded domains in SYD-2 that inhibits phase separation by an intrinsically disordered region (IDR). We find synaptic cell adhesion molecules localize SAD-1 to nascent synapses upstream of active zone formation. We conclude that SAD-1 phosphorylates SYD-2 at developing synapses, activating its phase separation and active zone assembly.
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Affiliation(s)
- Nathan A. McDonald
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Li Tao
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, People’s Republic of China
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University, Stanford, California, United States of America
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4
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Frankel EB, Tiroumalechetty A, Henry PS, Su Z, Wu Y, Kurshan PT. Protein-lipid interactions drive presynaptic assembly upstream of cell adhesion molecules. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.17.567618. [PMID: 38014115 PMCID: PMC10680821 DOI: 10.1101/2023.11.17.567618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Textbook models of synaptogenesis position cell adhesion molecules such as neurexin as initiators of synapse assembly. Here we discover a mechanism for presynaptic assembly that occurs prior to neurexin recruitment, while supporting a role for neurexin in synapse maintenance. We find that the cytosolic active zone scaffold SYD-1 interacts with membrane phospholipids to promote active zone protein clustering at the plasma membrane, and subsequently recruits neurexin to stabilize those clusters. Employing molecular dynamics simulations to model intrinsic interactions between SYD-1 and lipid bilayers followed by in vivo tests of these predictions, we find that PIP2-interacting residues in SYD-1's C2 and PDZ domains are redundantly necessary for proper active zone assembly. Finally, we propose that the uncharacterized yet evolutionarily conserved short γ isoform of neurexin represents a minimal neurexin sequence that can stabilize previously assembled presynaptic clusters, potentially a core function of this critical protein.
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Affiliation(s)
- Elisa B Frankel
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | | | - Parise S Henry
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Zhaoqian Su
- Data Science Institute, Vanderbilt University, 1001 19th Ave S, Nashville, TN, 37212
| | - Yinghao Wu
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Peri T Kurshan
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
- Lead Contact
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5
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Ramesh N, Escher M, Turrel O, Lützkendorf J, Matkovic T, Liu F, Sigrist SJ. An antagonism between Spinophilin and Syd-1 operates upstream of memory-promoting presynaptic long-term plasticity. eLife 2023; 12:e86084. [PMID: 37767892 PMCID: PMC10588984 DOI: 10.7554/elife.86084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
We still face fundamental gaps in understanding how molecular plastic changes of synapses intersect with circuit operation to define behavioral states. Here, we show that an antagonism between two conserved regulatory proteins, Spinophilin (Spn) and Syd-1, controls presynaptic long-term plasticity and the maintenance of olfactory memories in Drosophila. While Spn mutants could not trigger nanoscopic active zone remodeling under homeostatic challenge and failed to stably potentiate neurotransmitter release, concomitant reduction of Syd-1 rescued all these deficits. The Spn/Syd-1 antagonism converged on active zone close F-actin, and genetic or acute pharmacological depolymerization of F-actin rescued the Spn deficits by allowing access to synaptic vesicle release sites. Within the intrinsic mushroom body neurons, the Spn/Syd-1 antagonism specifically controlled olfactory memory stabilization but not initial learning. Thus, this evolutionarily conserved protein complex controls behaviorally relevant presynaptic long-term plasticity, also observed in the mammalian brain but still enigmatic concerning its molecular mechanisms and behavioral relevance.
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Affiliation(s)
- Niraja Ramesh
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | - Marc Escher
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | - Oriane Turrel
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | | | - Tanja Matkovic
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
| | - Fan Liu
- Leibniz-Forschungsinstitut für Molekulare PharmakologieBerlinGermany
| | - Stephan J Sigrist
- Institute for Biology/Genetics, Freie Universität BerlinBerlinGermany
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6
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Chohan Y, Eitzman EA, Hawkins WD, Klionsky DJ. Bruchpiloting synaptic connections: Egfr in autophagy-mediated neuronal circuit development. Autophagy 2023; 19:1899-1900. [PMID: 37243688 PMCID: PMC10283405 DOI: 10.1080/15548627.2023.2217015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 05/29/2023] Open
Abstract
Macroautophagy/autophagy is involved in many aspects of human development including the formation of neuronal circuits. A recent study from Dutta et al. found that the recruitment of Egfr (Epidermal growth factor receptor) to synapses suppresses autophagic degradation of presynaptic proteins, a requirement for proper neuronal circuit development. The findings suggest that Egfr inactivation during a distinct critical interval in late development results in increased levels of autophagy in the brain and decreased neuronal circuit development. Furthermore, the presence of brp (bruchpilot) in the synapse is critical for proper neuronal functioning over this same period. Dutta and colleagues found that increased autophagy due to Egfr inactivation results in decreased brp levels and, therefore, reduced neuronal connectivity. Through live cell imaging, it was determined that only the synaptic branches that accumulate both Egfr and brp are stabilized, allowing for the persistence of active zones, further supporting the importance of both Egfr and brp in the brain. While Dutta and colleagues collected these data based on studies conducted on Drosophila brains, the findings provide great insight as to how these different proteins may be implicated in human neurology.
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Affiliation(s)
- Yashveer Chohan
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Emily A. Eitzman
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Wayne D. Hawkins
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Daniel J. Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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7
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Mueller BD, Merrill SA, Watanabe S, Liu P, Niu L, Singh A, Maldonado-Catala P, Cherry A, Rich MS, Silva M, Maricq AV, Wang ZW, Jorgensen EM. CaV1 and CaV2 calcium channels mediate the release of distinct pools of synaptic vesicles. eLife 2023; 12:e81407. [PMID: 36820519 PMCID: PMC10023163 DOI: 10.7554/elife.81407] [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: 06/25/2022] [Accepted: 02/22/2023] [Indexed: 02/24/2023] Open
Abstract
Activation of voltage-gated calcium channels at presynaptic terminals leads to local increases in calcium and the fusion of synaptic vesicles containing neurotransmitter. Presynaptic output is a function of the density of calcium channels, the dynamic properties of the channel, the distance to docked vesicles, and the release probability at the docking site. We demonstrate that at Caenorhabditis elegans neuromuscular junctions two different classes of voltage-gated calcium channels, CaV2 and CaV1, mediate the release of distinct pools of synaptic vesicles. CaV2 channels are concentrated in densely packed clusters ~250 nm in diameter with the active zone proteins Neurexin, α-Liprin, SYDE, ELKS/CAST, RIM-BP, α-Catulin, and MAGI1. CaV2 channels are colocalized with the priming protein UNC-13L and mediate the fusion of vesicles docked within 33 nm of the dense projection. CaV2 activity is amplified by ryanodine receptor release of calcium from internal stores, triggering fusion up to 165 nm from the dense projection. By contrast, CaV1 channels are dispersed in the synaptic varicosity, and are colocalized with UNC-13S. CaV1 and ryanodine receptors are separated by just 40 nm, and vesicle fusion mediated by CaV1 is completely dependent on the ryanodine receptor. Distinct synaptic vesicle pools, released by different calcium channels, could be used to tune the speed, voltage-dependence, and quantal content of neurotransmitter release.
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Affiliation(s)
- Brian D Mueller
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Sean A Merrill
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Shigeki Watanabe
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Ping Liu
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Longgang Niu
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Anish Singh
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | | | - Alex Cherry
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Matthew S Rich
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Malan Silva
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | | | - Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Erik M Jorgensen
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
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8
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Mizumoto K, Jin Y, Bessereau JL. Synaptogenesis: unmasking molecular mechanisms using Caenorhabditis elegans. Genetics 2023; 223:iyac176. [PMID: 36630525 PMCID: PMC9910414 DOI: 10.1093/genetics/iyac176] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/22/2022] [Indexed: 01/13/2023] Open
Abstract
The nematode Caenorhabditis elegans is a research model organism particularly suited to the mechanistic understanding of synapse genesis in the nervous system. Armed with powerful genetics, knowledge of complete connectomics, and modern genomics, studies using C. elegans have unveiled multiple key regulators in the formation of a functional synapse. Importantly, many signaling networks display remarkable conservation throughout animals, underscoring the contributions of C. elegans research to advance the understanding of our brain. In this chapter, we will review up-to-date information of the contribution of C. elegans to the understanding of chemical synapses, from structure to molecules and to synaptic remodeling.
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Affiliation(s)
- Kota Mizumoto
- Department of Zoology, University of British Columbia, Vancouver V6T 1Z3, Canada
| | - Yishi Jin
- Department of Neurobiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Jean-Louis Bessereau
- Univ Lyon, University Claude Bernard Lyon 1, CNRS UMR 5284, INSERM U 1314, Melis, 69008 Lyon, France
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9
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Jin Y, Zhai RG. Presynaptic Cytomatrix Proteins. ADVANCES IN NEUROBIOLOGY 2023; 33:23-42. [PMID: 37615862 DOI: 10.1007/978-3-031-34229-5_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
The Cytomatrix Assembled at the active Zone (CAZ) of a presynaptic terminal displays electron-dense appearance and defines the center of the synaptic vesicle release. The protein constituents of CAZ are multiple-domain scaffolds that interact extensively with each other and also with an ensemble of synaptic vesicle proteins to ensure docking, fusion, and recycling. Reflecting the central roles of the active zone in synaptic transmission, CAZ proteins are highly conserved throughout evolution. As the nervous system increases complexity and diversity in types of neurons and synapses, CAZ proteins expand in the number of gene and protein isoforms and interacting partners. This chapter summarizes the discovery of the core CAZ proteins and current knowledge of their functions.
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Affiliation(s)
- Yishi Jin
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, La Jolla, CA, USA.
| | - R Grace Zhai
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, USA.
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10
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Zhai RG. The Architecture of the Presynaptic Release Site. ADVANCES IN NEUROBIOLOGY 2023; 33:1-21. [PMID: 37615861 DOI: 10.1007/978-3-031-34229-5_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
The architecture of the presynaptic release site is exquisitely designed to facilitate and regulate synaptic vesicle exocytosis. With the identification of some of the building blocks of the active zone and the advent of super resolution imaging techniques, we are beginning to understand the morphological and functional properties of synapses in great detail. Presynaptic release sites consist of the plasma membrane, the cytomatrix, and dense projections. These three components are morphologically distinct but intimately connected with each other and with postsynaptic specializations, ensuring the fidelity of synaptic vesicle tethering, docking, and fusion, as well as signal detection. Although the morphology and molecular compositions of active zones may vary among species, tissues, and cells, global architectural design of the release sites is highly conserved.
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Affiliation(s)
- R Grace Zhai
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, USA.
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11
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Kouchi Z, Kojima M. Function of SYDE C2-RhoGAP family as signaling hubs for neuronal development deduced by computational analysis. Sci Rep 2022; 12:4325. [PMID: 35279680 PMCID: PMC8918327 DOI: 10.1038/s41598-022-08147-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 03/02/2022] [Indexed: 11/21/2022] Open
Abstract
Recent investigations of neurological developmental disorders have revealed the Rho-family modulators such as Syde and its interactors as the candidate genes. Although the mammalian Syde proteins are reported to possess GTPase-accelerating activity for RhoA-family proteins, diverse species-specific substrate selectivities and binding partners have been described, presumably based on their evolutionary variance in the molecular organization. A comprehensive in silico analysis of Syde family proteins was performed to elucidate their molecular functions and neurodevelopmental networks. Predicted structural modeling of the RhoGAP domain may account for the molecular constraints to substrate specificity among Rho-family proteins. Deducing conserved binding motifs can extend the Syde interaction network and highlight diverse but Syde isoform-specific signaling pathways in neuronal homeostasis, differentiation, and synaptic plasticity from novel aspects of post-translational modification and proteolysis.
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12
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Moseley-Alldredge M, Sheoran S, Yoo H, O’Keefe C, Richmond JE, Chen L. A role for the Erk MAPK pathway in modulating SAX-7/L1CAM-dependent locomotion in Caenorhabditis elegans. Genetics 2022; 220:iyab215. [PMID: 34849872 PMCID: PMC9097276 DOI: 10.1093/genetics/iyab215] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 11/11/2021] [Indexed: 01/13/2023] Open
Abstract
L1CAMs are immunoglobulin cell adhesion molecules that function in nervous system development and function. Besides being associated with autism and schizophrenia spectrum disorders, impaired L1CAM function also underlies the X-linked L1 syndrome, which encompasses a group of neurological conditions, including spastic paraplegia and congenital hydrocephalus. Studies on vertebrate and invertebrate L1CAMs established conserved roles that include axon guidance, dendrite morphogenesis, synapse development, and maintenance of neural architecture. We previously identified a genetic interaction between the Caenorhabditis elegans L1CAM encoded by the sax-7 gene and RAB-3, a GTPase that functions in synaptic neurotransmission; rab-3; sax-7 mutant animals exhibit synthetic locomotion abnormalities and neuronal dysfunction. Here, we show that this synergism also occurs when loss of SAX-7 is combined with mutants of other genes encoding key players of the synaptic vesicle (SV) cycle. In contrast, sax-7 does not interact with genes that function in synaptogenesis. These findings suggest a postdevelopmental role for sax-7 in the regulation of synaptic activity. To assess this possibility, we conducted electrophysiological recordings and ultrastructural analyses at neuromuscular junctions; these analyses did not reveal obvious synaptic abnormalities. Lastly, based on a forward genetic screen for suppressors of the rab-3; sax-7 synthetic phenotypes, we determined that mutants in the ERK Mitogen-activated Protein Kinase (MAPK) pathway can suppress the rab-3; sax-7 locomotion defects. Moreover, we established that Erk signaling acts in a subset of cholinergic neurons in the head to promote coordinated locomotion. In combination, these results suggest a modulatory role for Erk MAPK in L1CAM-dependent locomotion in C. elegans.
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Affiliation(s)
- Melinda Moseley-Alldredge
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
- Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Seema Sheoran
- Department of Biological Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Hayoung Yoo
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Calvin O’Keefe
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Lihsia Chen
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
- Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
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13
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Liprins in oncogenic signaling and cancer cell adhesion. Oncogene 2021; 40:6406-6416. [PMID: 34654889 PMCID: PMC8602034 DOI: 10.1038/s41388-021-02048-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/21/2021] [Accepted: 09/28/2021] [Indexed: 12/30/2022]
Abstract
Liprins are a multifunctional family of scaffold proteins, identified by their involvement in several important neuronal functions related to signaling and organization of synaptic structures. More recently, the knowledge on the liprin family has expanded from neuronal functions to processes relevant to cancer progression, including cell adhesion, cell motility, cancer cell invasion, and signaling. These proteins consist of regions, which by prediction are intrinsically disordered, and may be involved in the assembly of supramolecular structures relevant for their functions. This review summarizes the current understanding of the functions of liprins in different cellular processes, with special emphasis on liprins in tumor progression. The available data indicate that liprins may be potential biomarkers for cancer progression and may have therapeutic importance.
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14
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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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15
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Zhou X, Bessereau JL. Molecular Architecture of Genetically-Tractable GABA Synapses in C. elegans. Front Mol Neurosci 2019; 12:304. [PMID: 31920535 PMCID: PMC6920096 DOI: 10.3389/fnmol.2019.00304] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/26/2019] [Indexed: 12/18/2022] Open
Abstract
Inhibitory synapses represent a minority of the total chemical synapses in the mammalian brain, yet proper tuning of inhibition is fundamental to shape neuronal network properties. The neurotransmitter γ-aminobutyric acid (GABA) mediates rapid synaptic inhibition by the activation of the type A GABA receptor (GABAAR), a pentameric chloride channel that governs major inhibitory neuronal transduction in the nervous system. Impaired GABA transmission leads to a variety of neuropsychiatric diseases, including schizophrenia, autism, epilepsy or anxiety. From an evolutionary perspective, GABAAR shows remarkable conservations, and are found in all eukaryotic clades and even in bacteria and archaea. Specifically, bona fide GABAARs are found in the nematode Caenorhabditis elegans. Because of the anatomical simplicity of the nervous system and its amenability to genetic manipulations, C. elegans provide a powerful system to investigate the molecular and cellular biology of GABA synapses. In this mini review article, we will introduce the structure of the C. elegans GABAergic system and describe recent advances that have identified novel proteins controlling the localization of GABAARs at synapses. In particular, Ce-Punctin/MADD-4 is an evolutionarily-conserved extracellular matrix protein that behaves as an anterograde synaptic organizer to instruct the excitatory or inhibitory identity of postsynaptic domains.
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Affiliation(s)
- Xin Zhou
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Jean-Louis Bessereau
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
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16
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Nomoto Y, Kubota Y, Ohnishi Y, Kasahara K, Tomita A, Oshime T, Yamashita H, Fahmi M, Ito M. Gene Cascade Finder: A tool for identification of gene cascades and its application in Caenorhabditis elegans. PLoS One 2019; 14:e0215187. [PMID: 31504044 PMCID: PMC6736238 DOI: 10.1371/journal.pone.0215187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 08/06/2019] [Indexed: 11/24/2022] Open
Abstract
Obtaining a comprehensive understanding of the gene regulatory networks, or gene cascades, involved in cell fate determination and cell lineage segregation in Caenorhabditis elegans is a long-standing challenge. Although RNA-sequencing (RNA-Seq) is a promising technique to resolve these questions, the bioinformatics tools to identify associated gene cascades from RNA-Seq data remain inadequate. To overcome these limitations, we developed Gene Cascade Finder (GCF) as a novel tool for building gene cascades by comparison of mutant and wild-type RNA-Seq data along with integrated information of protein-protein interactions, expression timing, and domains. Application of GCF to RNA-Seq data confirmed that SPN-4 and MEX-3 regulate the canonical Wnt pathway during embryonic development. Moreover, lin-35, hsp-3, and gpa-12 were found to be involved in MEX-1-dependent neurogenesis, and MEX-3 was found to control the gene cascade promoting neurogenesis through lin-35 and apl-1. Thus, GCF could be a useful tool for building gene cascades from RNA-Seq data.
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Affiliation(s)
- Yusuke Nomoto
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Yukihiro Kubota
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Yuto Ohnishi
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Kota Kasahara
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Aimi Tomita
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Takehiro Oshime
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Hiroki Yamashita
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Muhamad Fahmi
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Masahiro Ito
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- * E-mail:
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17
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Özel MN, Kulkarni A, Hasan A, Brummer J, Moldenhauer M, Daumann IM, Wolfenberg H, Dercksen VJ, Kiral FR, Weiser M, Prohaska S, von Kleist M, Hiesinger PR. Serial Synapse Formation through Filopodial Competition for Synaptic Seeding Factors. Dev Cell 2019; 50:447-461.e8. [PMID: 31353313 DOI: 10.1016/j.devcel.2019.06.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 05/15/2019] [Accepted: 06/21/2019] [Indexed: 11/15/2022]
Abstract
Following axon pathfinding, growth cones transition from stochastic filopodial exploration to the formation of a limited number of synapses. How the interplay of filopodia and synapse assembly ensures robust connectivity in the brain has remained a challenging problem. Here, we developed a new 4D analysis method for filopodial dynamics and a data-driven computational model of synapse formation for R7 photoreceptor axons in developing Drosophila brains. Our live data support a "serial synapse formation" model, where at any time point only 1-2 "synaptogenic" filopodia suppress the synaptic competence of other filopodia through competition for synaptic seeding factors. Loss of the synaptic seeding factors Syd-1 and Liprin-α leads to a loss of this suppression, filopodial destabilization, and reduced synapse formation. The failure to form synapses can cause the destabilization and secondary retraction of axon terminals. Our model provides a filopodial "winner-takes-all" mechanism that ensures the formation of an appropriate number of synapses.
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Affiliation(s)
- M Neset Özel
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany; Neuroscience Graduate Program, UT Southwestern Medical Center Dallas, Dallas, TX 75390, USA
| | - Abhishek Kulkarni
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Amr Hasan
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Josephine Brummer
- Department of Visual Data Analysis, Zuse Institute Berlin, 14195 Berlin, Germany
| | - Marian Moldenhauer
- Computational Medicine and Numerical Mathematics, Zuse Institute Berlin, 14195 Berlin, Germany; Department of Mathematics and Informatics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Ilsa-Maria Daumann
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Heike Wolfenberg
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Vincent J Dercksen
- Department of Visual Data Analysis, Zuse Institute Berlin, 14195 Berlin, Germany
| | - F Ridvan Kiral
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Martin Weiser
- Computational Medicine and Numerical Mathematics, Zuse Institute Berlin, 14195 Berlin, Germany
| | - Steffen Prohaska
- Department of Visual Data Analysis, Zuse Institute Berlin, 14195 Berlin, Germany
| | - Max von Kleist
- Department of Mathematics and Informatics, Freie Universität Berlin, 14195 Berlin, Germany.
| | - P Robin Hiesinger
- Division of Neurobiology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany.
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18
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Hendi A, Kurashina M, Mizumoto K. Intrinsic and extrinsic mechanisms of synapse formation and specificity in C. elegans. Cell Mol Life Sci 2019; 76:2719-2738. [PMID: 31037336 PMCID: PMC11105629 DOI: 10.1007/s00018-019-03109-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/11/2019] [Accepted: 04/15/2019] [Indexed: 12/18/2022]
Abstract
Precise neuronal wiring is critical for the function of the nervous system and is ultimately determined at the level of individual synapses. Neurons integrate various intrinsic and extrinsic cues to form synapses onto their correct targets in a stereotyped manner. In the past decades, the nervous system of nematode (Caenorhabditis elegans) has provided the genetic platform to reveal the genetic and molecular mechanisms of synapse formation and specificity. In this review, we will summarize the recent discoveries in synapse formation and specificity in C. elegans.
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Affiliation(s)
- Ardalan Hendi
- Department of Zoology, The University of British Columbia, 2406-2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Mizuki Kurashina
- Department of Zoology, The University of British Columbia, 2406-2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Kota Mizumoto
- Department of Zoology, The University of British Columbia, 2406-2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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19
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Böhme MA, McCarthy AW, Grasskamp AT, Beuschel CB, Goel P, Jusyte M, Laber D, Huang S, Rey U, Petzoldt AG, Lehmann M, Göttfert F, Haghighi P, Hell SW, Owald D, Dickman D, Sigrist SJ, Walter AM. Rapid active zone remodeling consolidates presynaptic potentiation. Nat Commun 2019; 10:1085. [PMID: 30842428 PMCID: PMC6403334 DOI: 10.1038/s41467-019-08977-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 02/07/2019] [Indexed: 01/22/2023] Open
Abstract
Neuronal communication across synapses relies on neurotransmitter release from presynaptic active zones (AZs) followed by postsynaptic transmitter detection. Synaptic plasticity homeostatically maintains functionality during perturbations and enables memory formation. Postsynaptic plasticity targets neurotransmitter receptors, but presynaptic mechanisms regulating the neurotransmitter release apparatus remain largely enigmatic. By studying Drosophila neuromuscular junctions (NMJs) we show that AZs consist of nano-modular release sites and identify a molecular sequence that adds modules within minutes of inducing homeostatic plasticity. This requires cognate transport machinery and specific AZ-scaffolding proteins. Structural remodeling is not required for immediate potentiation of neurotransmitter release, but necessary to sustain potentiation over longer timescales. Finally, mutations in Unc13 disrupting homeostatic plasticity at the NMJ also impair short-term memory when central neurons are targeted, suggesting that both plasticity mechanisms utilize Unc13. Together, while immediate synaptic potentiation capitalizes on available material, it triggers the coincident incorporation of modular release sites to consolidate synaptic potentiation.
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Affiliation(s)
- Mathias A Böhme
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin, 10117, Berlin, Germany.,Institute for Biology/Genetics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Anthony W McCarthy
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany
| | - Andreas T Grasskamp
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin, 10117, Berlin, Germany
| | - Christine B Beuschel
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, 10117, Berlin, Germany.,Institute for Biology/Genetics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Meida Jusyte
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany
| | - Desiree Laber
- Institut für Neurophysiologie, Charité Universitätsmedizin, 10117, Berlin, Germany
| | - Sheng Huang
- Institute for Biology/Genetics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Ulises Rey
- Institute for Biology/Genetics, Freie Universität Berlin, 14195, Berlin, Germany.,Department of Theory and Bio-systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany
| | - Astrid G Petzoldt
- Institute for Biology/Genetics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany
| | - Fabian Göttfert
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | | | - Stefan W Hell
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | - David Owald
- Institut für Neurophysiologie, Charité Universitätsmedizin, 10117, Berlin, Germany
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Stephan J Sigrist
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, 10117, Berlin, Germany. .,Institute for Biology/Genetics, Freie Universität Berlin, 14195, Berlin, Germany.
| | - Alexander M Walter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany.
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20
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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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21
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Edwards SL, Morrison LM, Manning L, Stec N, Richmond JE, Miller KG. Sentryn Acts with a Subset of Active Zone Proteins To Optimize the Localization of Synaptic Vesicles in Caenorhabditis elegans. Genetics 2018; 210:947-968. [PMID: 30401765 PMCID: PMC6218225 DOI: 10.1534/genetics.118.301466] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 08/27/2018] [Indexed: 01/22/2023] Open
Abstract
Synaptic vesicles (SVs) transmit signals by releasing neurotransmitters from specialized synaptic regions of neurons. In the synaptic region, SVs are tightly clustered around small structures called active zones. The motor KIF1A transports SVs outward through axons until they are captured in the synaptic region. This transport must be guided in the forward direction because it is opposed by the dynein motor, which causes SVs to reverse direction multiple times en route. The core synapse stability (CSS) system contributes to both guided transport and capture of SVs. We identified Sentryn as a CSS protein that contributes to the synaptic localization of SVs in Caenorhabditis elegans Like the CSS proteins SAD Kinase and SYD-2 (Liprin-α), Sentryn also prevents dynein-dependent accumulation of lysosomes in dendrites in strains lacking JIP3. Genetic analysis showed that Sentryn and SAD Kinase each have at least one nonoverlapping function for the stable accumulation of SVs at synapses that, when combined with their shared functions, enables most of the functions of SYD-2 (Liprin-α) for capturing SVs. Also like other CSS proteins, Sentryn appears enriched at active zones and contributes to active zone structure, suggesting that it is a novel, conserved active zone protein. Sentryn is recruited to active zones by a process dependent on the active zone-enriched CSS protein SYD-2 (Liprin-α). Our results define a specialized group of active zone enriched proteins that can affect motorized transport throughout the neuron and that have roles in both guided transport and capture of SVs.
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Affiliation(s)
- Stacey L Edwards
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
| | - Logan M Morrison
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Illinois 60607
| | - Natalia Stec
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Illinois 60607
| | - Kenneth G Miller
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
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22
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Ghelani T, Sigrist SJ. Coupling the Structural and Functional Assembly of Synaptic Release Sites. Front Neuroanat 2018; 12:81. [PMID: 30386217 PMCID: PMC6198076 DOI: 10.3389/fnana.2018.00081] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 09/18/2018] [Indexed: 01/04/2023] Open
Abstract
Information processing in our brains depends on the exact timing of calcium (Ca2+)-activated exocytosis of synaptic vesicles (SVs) from unique release sites embedded within the presynaptic active zones (AZs). While AZ scaffolding proteins obviously provide an efficient environment for release site function, the molecular design creating such release sites had remained unknown for a long time. Recent advances in visualizing the ultrastructure and topology of presynaptic protein architectures have started to elucidate how scaffold proteins establish “nanodomains” that connect voltage-gated Ca2+ channels (VGCCs) physically and functionally with release-ready SVs. Scaffold proteins here seem to operate as “molecular rulers or spacers,” regulating SV-VGCC physical distances within tens of nanometers and, thus, influence the probability and plasticity of SV release. A number of recent studies at Drosophila and mammalian synapses show that the stable positioning of discrete clusters of obligate release factor (M)Unc13 defines the position of SV release sites, and the differential expression of (M)Unc13 isoforms at synapses can regulate SV-VGCC coupling. We here review the organization of matured AZ scaffolds concerning their intrinsic organization and role for release site formation. Moreover, we also discuss insights into the developmental sequence of AZ assembly, which often entails a tightening between VGCCs and SV release sites. The findings discussed here are retrieved from vertebrate and invertebrate preparations and include a spectrum of methods ranging from cell biology, super-resolution light and electron microscopy to biophysical and electrophysiological analysis. Our understanding of how the structural and functional organization of presynaptic AZs are coupled has matured, as these processes are crucial for the understanding of synapse maturation and plasticity, and, thus, accurate information transfer and storage at chemical synapses.
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Affiliation(s)
- Tina Ghelani
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Stephan J Sigrist
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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23
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Böhme MA, Grasskamp AT, Walter AM. Regulation of synaptic release-site Ca 2+ channel coupling as a mechanism to control release probability and short-term plasticity. FEBS Lett 2018; 592:3516-3531. [PMID: 29993122 DOI: 10.1002/1873-3468.13188] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/26/2018] [Accepted: 07/06/2018] [Indexed: 12/31/2022]
Abstract
Synaptic transmission relies on the rapid fusion of neurotransmitter-containing synaptic vesicles (SVs), which happens in response to action potential (AP)-induced Ca2+ influx at active zones (AZs). A highly conserved molecular machinery cooperates at SV-release sites to mediate SV plasma membrane attachment and maturation, Ca2+ sensing, and membrane fusion. Despite this high degree of conservation, synapses - even within the same organism, organ or neuron - are highly diverse regarding the probability of APs to trigger SV fusion. Additionally, repetitive activation can lead to either strengthening or weakening of transmission. In this review, we discuss mechanisms controlling release probability and this short-term plasticity. We argue that an important layer of control is exerted by evolutionarily conserved AZ scaffolding proteins, which determine the coupling distance between SV fusion sites and voltage-gated Ca2+ channels (VGCC) and, thereby, shape synapse-specific input/output behaviors. We propose that AZ-scaffold modifications may occur to adapt the coupling distance during synapse maturation and plastic regulation of synapse strength.
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Affiliation(s)
- Mathias A Böhme
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Alexander M Walter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
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24
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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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25
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Shi Y, Li Q, Shao Z. Wnts Promote Synaptic Assembly Through T-Cell Specific Transcription Factors in Caenorhabditis elegans. Front Mol Neurosci 2018; 11:194. [PMID: 29962933 PMCID: PMC6013564 DOI: 10.3389/fnmol.2018.00194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/16/2018] [Indexed: 12/19/2022] Open
Abstract
Synapses are specialized neuronal connections essential for neuronal function. Defects in synaptic assembly or maintenance usually lead to various neurological disorders. Synaptic assembly is regulated by secreted molecules such as Wnts. Wnts are a large family of conserved glycosylated signaling molecules involved in many aspects of neural development and maintenance. However, the molecular mechanisms by which Wnts regulate synaptic assembly remain elusive due to the large number of ligands/receptors, the diversity of signaling cascades and the complexity of the nervous system. In this study, through genetic manipulation, we uncover that C. elegans Wnt-2 (CWN-2) is required for synaptic development. The CWN-2 signal is required during both embryonic and postembryonic development, in the nervous system and intestine, for promoting synaptic assembly. Furthermore, we provide genetic evidence for CWN-2 promoting synaptogenesis through the Frizzled receptor (FZD) CFZ-2, the Dishevelled (DVL) DSH-2, the β-catenin SYS-1 and the only T-cell specific transcription factor POP-1/TCF. Importantly, it is the first time to report the requirement of a TCF for presynaptic assembly. These findings expand our understanding of the synaptogenic mechanisms and may provide therapeutic insights into Wnt-related neurological disorders.
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Affiliation(s)
- Yanjun Shi
- Department of Neurology, State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qian Li
- Department of Neurology, State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhiyong Shao
- Department of Neurology, State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
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26
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Drosophila Syd-1 Has RhoGAP Activity That Is Required for Presynaptic Clustering of Bruchpilot/ELKS but Not Neurexin-1. Genetics 2017; 208:705-716. [PMID: 29217522 DOI: 10.1534/genetics.117.300538] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 11/22/2017] [Indexed: 12/23/2022] Open
Abstract
Syd-1 proteins are required for presynaptic development in worm, fly, and mouse. Syd-1 proteins in all three species contain a Rho GTPase activating protein (GAP)-like domain of unclear significance: invertebrate Syd-1s are thought to lack GAP activity, and mouse mSYD1A has GAP activity that is thought to be dispensable for its function. Here, we show that Drosophila melanogaster Syd-1 can interact with all six fly Rhos and has GAP activity toward Rac1 and Cdc42. During development, fly Syd-1 clusters multiple presynaptic proteins at the neuromuscular junction (NMJ), including the cell adhesion molecule Neurexin (Nrx-1) and the active zone (AZ) component Bruchpilot (Brp), both of which Syd-1 binds directly. We show that a mutant form of Syd-1 that specifically lacks GAP activity localizes normally to presynaptic sites and is sufficient to recruit Nrx-1 but fails to cluster Brp normally. We provide evidence that Syd-1 participates with Rac1 in two separate functions: (1) together with the Rac guanine exchange factor (RacGEF) Trio, GAP-active Syd-1 is required to regulate the nucleotide-bound state of Rac1, thereby promoting Brp clustering; and (2) Syd-1, independent of its GAP activity, is required for the recruitment of Nrx-1 to boutons, including the recruitment of Nrx-1 that is promoted by GTP-bound Rac1. We conclude that, contrary to current models, the GAP domain of fly Syd-1 is active and required for presynaptic development; we suggest that the same may be true of vertebrate Syd-1 proteins. In addition, our data provide new molecular insight into the ability of Rac1 to promote presynaptic development.
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27
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Xuan Z, Manning L, Nelson J, Richmond JE, Colón-Ramos DA, Shen K, Kurshan PT. Clarinet (CLA-1), a novel active zone protein required for synaptic vesicle clustering and release. eLife 2017; 6:29276. [PMID: 29160205 PMCID: PMC5728718 DOI: 10.7554/elife.29276] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 11/20/2017] [Indexed: 01/03/2023] Open
Abstract
Active zone proteins cluster synaptic vesicles at presynaptic terminals and coordinate their release. In forward genetic screens, we isolated a novel Caenorhabditis elegans active zone gene, clarinet (cla-1). cla-1 mutants exhibit defects in synaptic vesicle clustering, active zone structure and synapse number. As a result, they have reduced spontaneous vesicle release and increased synaptic depression. cla-1 mutants show defects in vesicle distribution near the presynaptic dense projection, with fewer undocked vesicles contacting the dense projection and more docked vesicles at the plasma membrane. cla-1 encodes three isoforms containing common C-terminal PDZ and C2 domains with homology to vertebrate active zone proteins Piccolo and RIM. The C-termini of all isoforms localize to the active zone. Specific loss of the ~9000 amino acid long isoform results in vesicle clustering defects and increased synaptic depression. Our data indicate that specific isoforms of clarinet serve distinct functions, regulating synapse development, vesicle clustering and release.
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Affiliation(s)
- Zhao Xuan
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Jessica Nelson
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Daniel A Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States.,Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico, San Juan, Puerto Rico
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, United States.,Howard Hughes Medical Institute
| | - Peri T Kurshan
- Department of Biology, Stanford University, Stanford, United States
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28
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Yu B, Wang X, Wei S, Fu T, Dzakah EE, Waqas A, Walthall WW, Shan G. Convergent Transcriptional Programs Regulate cAMP Levels in C. elegans GABAergic Motor Neurons. Dev Cell 2017; 43:212-226.e7. [PMID: 29033363 DOI: 10.1016/j.devcel.2017.09.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 06/26/2017] [Accepted: 09/15/2017] [Indexed: 02/07/2023]
Abstract
Both transcriptional regulation and signaling pathways play crucial roles in neuronal differentiation and plasticity. Caenorhabditis elegans possesses 19 GABAergic motor neurons (MNs) called D MNs, which are divided into two subgroups: DD and VD. DD, but not VD, MNs reverse their cellular polarity in a developmental process called respecification. UNC-30 and UNC-55 are two critical transcription factors in D MNs. By using chromatin immunoprecipitation with CRISPR/Cas9 knockin of GFP fusion, we uncovered the global targets of UNC-30 and UNC-55. UNC-30 and UNC-55 are largely converged to regulate over 1,300 noncoding and coding genes, and genes in multiple biological processes, including cAMP metabolism, are co-regulated. Increase in cAMP levels may serve as a timing signal for respecification, whereas UNC-55 regulates genes such as pde-4 to keep the cAMP levels low in VD. Other genes modulating DD respecification such as lin-14, irx-1, and oig-1 are also found to affect cAMP levels.
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Affiliation(s)
- Bin Yu
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Xiaolin Wang
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Shuai Wei
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Tao Fu
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Emmanuel Enoch Dzakah
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Ahmed Waqas
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China
| | - Walter W Walthall
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Ge Shan
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China.
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29
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Barbagallo B, Philbrook A, Touroutine D, Banerjee N, Oliver D, Lambert CM, Francis MM. Excitatory neurons sculpt GABAergic neuronal connectivity in the C. elegans motor circuit. Development 2017; 144:1807-1819. [PMID: 28420711 DOI: 10.1242/dev.141911] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 04/03/2017] [Indexed: 11/20/2022]
Abstract
Establishing and maintaining the appropriate number of GABA synapses is key for balancing excitation and inhibition in the nervous system, though we have only a limited understanding of the mechanisms controlling GABA circuit connectivity. Here, we show that disrupting cholinergic innervation of GABAergic neurons in the C. elegans motor circuit alters GABAergic neuron synaptic connectivity. These changes are accompanied by reduced frequency and increased amplitude of GABAergic synaptic events. Acute genetic disruption in early development, during the integration of post-embryonic-born GABAergic neurons into the circuit, produces irreversible effects on GABAergic synaptic connectivity that mimic those produced by chronic manipulations. In contrast, acute genetic disruption of cholinergic signaling in the adult circuit does not reproduce these effects. Our findings reveal that GABAergic signaling is regulated by cholinergic neuronal activity, probably through distinct mechanisms in the developing and mature nervous system.
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Affiliation(s)
- Belinda Barbagallo
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Alison Philbrook
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Denis Touroutine
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Navonil Banerjee
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Devyn Oliver
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Christopher M Lambert
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Michael M Francis
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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30
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Guo W, Cai Y, Zhang H, Yang Y, Yang G, Wang X, Zhao J, Lin J, Zhu J, Li W, Lv L. Association of ARHGAP18 polymorphisms with schizophrenia in the Chinese-Han population. PLoS One 2017; 12:e0175209. [PMID: 28384650 PMCID: PMC5383423 DOI: 10.1371/journal.pone.0175209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 03/22/2017] [Indexed: 11/23/2022] Open
Abstract
Numerous developmental genes have been linked to schizophrenia (SZ) by case-control and genome-wide association studies, suggesting that neurodevelopmental disturbances are major pathogenic mechanisms. However, no neurodevelopmental deficit has been definitively linked to SZ occurrence, likely due to disease heterogeneity and the differential effects of various gene variants across ethnicities. Hence, it is critical to examine linkages in specific ethnic populations, such as Han Chinese. The newly identified RhoGAP ARHGAP18 is likely involved in neurodevelopment through regulation of RhoA/C. Here we describe four single nucleotide polymorphisms (SNPs) in ARHGAP18 associated with SZ across a cohort of >2000 cases and controls from the Han population. Two SNPs, rs7758025 and rs9483050, displayed significant differences between case and control groups both in genotype (P = 0.0002 and P = 7.54×10−6) and allelic frequencies (P = 4.36×10−5 and P = 5.98×10−7), respectively. The AG haplotype in rs7758025−rs9385502 was strongly associated with the occurrence of SZ (P = 0.0012, OR = 0.67, 95% CI = 0.48–0.93), an association that still held following a 1000-times random permutation test (P = 0.022). In an independently collected validation cohort, rs9483050 was the SNP most strongly associated with SZ. In addition, the allelic frequencies of rs12197901 remained associated with SZ in the combined cohort (P = 0.021), although not in the validation cohort alone (P = 0.251). Collectively, our data suggest the ARHGAP18 may confer vulnerability to SZ in the Chinese Han population, providing additional evidence for the involvement of neurodevelopmental dysfunction in the pathogenesis of schizophrenia.
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Affiliation(s)
- Weiyun Guo
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, China.,Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China
| | - Yaqi Cai
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Hongxing Zhang
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China.,Department of Psychology, Xinxiang Medical University, Xinxiang, China
| | - Yongfeng Yang
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Ge Yang
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Xiujuan Wang
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Jingyuan Zhao
- Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Juntang Lin
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, China.,Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Institute of Anatomy I, Friedrich Schiller University Jena, Jena, Germany
| | - Jinfu Zhu
- Institute of Anatomy I, Friedrich Schiller University Jena, Jena, Germany.,Department of Psychology, Xinxiang Medical University, Xinxiang, China
| | - Wenqiang Li
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Luxian Lv
- Henan Key Lab of Biological Psychiatry, Xinxiang Medical University, Xinxiang, China.,Department of Psychiatry, Henan Mental Hospital, The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
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31
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Anazi S, Maddirevula S, Faqeih E, Alsedairy H, Alzahrani F, Shamseldin HE, Patel N, Hashem M, Ibrahim N, Abdulwahab F, Ewida N, Alsaif HS, Al Sharif H, Alamoudi W, Kentab A, Bashiri FA, Alnaser M, AlWadei AH, Alfadhel M, Eyaid W, Hashem A, Al Asmari A, Saleh MM, AlSaman A, Alhasan KA, Alsughayir M, Al Shammari M, Mahmoud A, Al-Hassnan ZN, Al-Husain M, Osama Khalil R, Abd El Meguid N, Masri A, Ali R, Ben-Omran T, El Fishway P, Hashish A, Ercan Sencicek A, State M, Alazami AM, Salih MA, Altassan N, Arold ST, Abouelhoda M, Wakil SM, Monies D, Shaheen R, Alkuraya FS. Clinical genomics expands the morbid genome of intellectual disability and offers a high diagnostic yield. Mol Psychiatry 2017; 22:615-624. [PMID: 27431290 DOI: 10.1038/mp.2016.113] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/02/2016] [Accepted: 06/06/2016] [Indexed: 12/13/2022]
Abstract
Intellectual disability (ID) is a measurable phenotypic consequence of genetic and environmental factors. In this study, we prospectively assessed the diagnostic yield of genomic tools (molecular karyotyping, multi-gene panel and exome sequencing) in a cohort of 337 ID subjects as a first-tier test and compared it with a standard clinical evaluation performed in parallel. Standard clinical evaluation suggested a diagnosis in 16% of cases (54/337) but only 70% of these (38/54) were subsequently confirmed. On the other hand, the genomic approach revealed a likely diagnosis in 58% (n=196). These included copy number variants in 14% (n=54, 15% are novel), and point mutations revealed by multi-gene panel and exome sequencing in the remaining 43% (1% were found to have Fragile-X). The identified point mutations were mostly recessive (n=117, 81%), consistent with the high consanguinity of the study cohort, but also X-linked (n=8, 6%) and de novo dominant (n=19, 13%). When applied directly on all cases with negative molecular karyotyping, the diagnostic yield of exome sequencing was 60% (77/129). Exome sequencing also identified likely pathogenic variants in three novel candidate genes (DENND5A, NEMF and DNHD1) each of which harbored independent homozygous mutations in patients with overlapping phenotypes. In addition, exome sequencing revealed de novo and recessive variants in 32 genes (MAMDC2, TUBAL3, CPNE6, KLHL24, USP2, PIP5K1A, UBE4A, TP53TG5, ATOH1, C16ORF90, SLC39A14, TRERF1, RGL1, CDH11, SYDE2, HIRA, FEZF2, PROCA1, PIANP, PLK2, QRFPR, AP3B2, NUDT2, UFC1, BTN3A2, TADA1, ARFGEF3, FAM160B1, ZMYM5, SLC45A1, ARHGAP33 and CAPS2), which we highlight as potential candidates on the basis of several lines of evidence, and one of these genes (SLC39A14) was biallelically inactivated in a potentially treatable form of hypermanganesemia and neurodegeneration. Finally, likely causal variants in previously published candidate genes were identified (ASTN1, HELZ, THOC6, WDR45B, ADRA2B and CLIP1), thus supporting their involvement in ID pathogenesis. Our results expand the morbid genome of ID and support the adoption of genomics as a first-tier test for individuals with ID.
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Affiliation(s)
- S Anazi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - S Maddirevula
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - E Faqeih
- Department of Pediatric Subspecialties, Children's Hospital, King Fahad Medical City, Riyadh, Saudi Arabia
| | - H Alsedairy
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - F Alzahrani
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - H E Shamseldin
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - N Patel
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - M Hashem
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - N Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - F Abdulwahab
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - N Ewida
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - H S Alsaif
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - H Al Sharif
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - W Alamoudi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - A Kentab
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - F A Bashiri
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - M Alnaser
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - A H AlWadei
- Pediatric Neurology Department, National Neuroscience Institute, King Fahad Medical City, Riyadh, Saudi Arabia
| | - M Alfadhel
- Department of Pediatrics, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Riyadh, Saudi Arabia
| | - W Eyaid
- Department of Pediatrics, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Riyadh, Saudi Arabia
| | - A Hashem
- Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - A Al Asmari
- Department of Pediatric Subspecialties, Children's Hospital, King Fahad Medical City, Riyadh, Saudi Arabia
| | - M M Saleh
- Department of Pediatric Subspecialties, Children's Hospital, King Fahad Medical City, Riyadh, Saudi Arabia
| | - A AlSaman
- Pediatric Neurology Department, National Neuroscience Institute, King Fahad Medical City, Riyadh, Saudi Arabia
| | - K A Alhasan
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - M Alsughayir
- Department of Psychiatry, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - M Al Shammari
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - A Mahmoud
- Pediatric Neurology Department, National Neuroscience Institute, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Z N Al-Hassnan
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - M Al-Husain
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - R Osama Khalil
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA.,National Research Center, Cairo, Egypt
| | | | - A Masri
- Department of Pediatrics, Faculty of Medicine, The University of Jordan, Amman, Jordan
| | - R Ali
- Clinical & Metabolic Genetics, Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - T Ben-Omran
- Clinical & Metabolic Genetics, Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - P El Fishway
- Department of Neurosurgery, Program on Neurogenetics, Yale University School of Medicine, New Haven, CT, USA
| | - A Hashish
- National Research Center, Cairo, Egypt
| | - A Ercan Sencicek
- Department of Neurosurgery, Program on Neurogenetics, Yale University School of Medicine, New Haven, CT, USA
| | - M State
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA
| | - A M Alazami
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - M A Salih
- Department of Pediatrics, College of Medicine & King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - N Altassan
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - S T Arold
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, Saudi Arabia
| | - M Abouelhoda
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - S M Wakil
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - D Monies
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - R Shaheen
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - F S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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32
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Huang GH, Sun ZL, Li HJ, Feng DF. Rho GTPase-activating proteins: Regulators of Rho GTPase activity in neuronal development and CNS diseases. Mol Cell Neurosci 2017; 80:18-31. [PMID: 28163190 DOI: 10.1016/j.mcn.2017.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 01/06/2017] [Accepted: 01/29/2017] [Indexed: 12/22/2022] Open
Abstract
The Rho family of small GTPases was considered as molecular switches in regulating multiple cellular events, including cytoskeleton reorganization. The Rho GTPase-activating proteins (RhoGAPs) are one of the major families of Rho GTPase regulators. RhoGAPs were initially considered negative mediators of Rho signaling pathways via their GAP domain. Recent studies have demonstrated that RhoGAPs also regulate numerous aspects of neuronal development and are related to various neurodegenerative diseases in GAP-dependent and GAP-independent manners. Moreover, RhoGAPs are regulated through various mechanisms, such as phosphorylation. To date, approximately 70 RhoGAPs have been identified; however, only a small portion has been thoroughly investigated. Thus, the characterization of important RhoGAPs in the central nervous system is crucial to understand their spatiotemporal role during different stages of neuronal development. In this review, we summarize the current knowledge of RhoGAPs in the brain with an emphasis on their molecular function, regulation mechanism and disease implications in the central nervous system.
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Affiliation(s)
- Guo-Hui Huang
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Zhao-Liang Sun
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Hong-Jiang Li
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Dong-Fu Feng
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China; Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China.
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33
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Sheftic SR, Page R, Peti W. Investigating the human Calcineurin Interaction Network using the πɸLxVP SLiM. Sci Rep 2016; 6:38920. [PMID: 27974827 PMCID: PMC5156906 DOI: 10.1038/srep38920] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 11/15/2016] [Indexed: 11/16/2022] Open
Abstract
Ser/thr phosphorylation is the primary reversible covalent modification of proteins in eukaryotes. As a consequence, it is the reciprocal actions of kinases and phosphatases that act as key molecular switches to fine tune cellular events. It has been well documented that ~400 human ser/thr kinases engage substrates via consensus phosphosite sequences. Strikingly, we know comparatively little about the mechanism by which ~40 human protein ser/thr phosphatases (PSPs) dephosphorylate ~15000 different substrates with high specificity. The identification of substrates of the essential PSP calcineurin (CN) has been exceptionally challenging and only a small fraction has been biochemically confirmed. It is now emerging that CN binds regulators and substrates via two short linear motifs (SLiMs), the well-studied PxIxIT SLiM and the LxVP SLiM, which remains controversial at the molecular level. Here we describe the crystal structure of CN in complex with its substrate NFATc1 and show that the LxVP SLiM is correctly defined as πɸLxVP. Bioinformatics studies using the πɸLxVP SLiM resulted in the identification of 567 potential CN substrates; a small subset was experimentally confirmed. This combined structural-bioinformatics approach provides a powerful method for dissecting the CN interaction network and for elucidating the role of CN in human health and disease.
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Affiliation(s)
- Sarah R Sheftic
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI, 02912, USA
| | - Rebecca Page
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02912, USA
| | - Wolfgang Peti
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI, 02912, USA.,Department of Chemistry, Brown University, Providence, RI, 02912, USA
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Xu Y, Quinn CC. SYD-1 Promotes Multiple Developmental Steps Leading to Neuronal Connectivity. Mol Neurobiol 2016; 53:6768-6773. [PMID: 26660112 PMCID: PMC5841450 DOI: 10.1007/s12035-015-9592-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 12/01/2015] [Indexed: 11/30/2022]
Abstract
The establishment of neuronal connectivity requires precise orchestration of multiple developmental steps, including axon specification, axon guidance, selection of synaptic target sites, and development of synaptic specializations. Although these are separate developmental steps, evidence indicates that some of the signaling molecules that regulate these steps are shared. In this review, we focus on SYD-1, a RhoGAP-like protein that has been implicated in each step of axonal development. We discuss interactions between SYD-1, UNC-40(DCC) and RhoGTPases and highlight both similarities and differences in how SYD-1 functions to regulate the different steps of axonal development. These observations reveal an example of how a signaling protein can be repurposed across sequential developmental steps.
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Affiliation(s)
- Yan Xu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | - Christopher C Quinn
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA.
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Xu Y, Quinn CC. Transition between synaptic branch formation and synaptogenesis is regulated by the lin-4 microRNA. Dev Biol 2016; 420:60-66. [PMID: 27746167 PMCID: PMC5841448 DOI: 10.1016/j.ydbio.2016.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/25/2016] [Accepted: 10/12/2016] [Indexed: 11/29/2022]
Abstract
Axonal branch formation and synaptogenesis are sequential events that are required for the establishment of neuronal connectivity. However, little is known about how the transition between these two events is regulated. Here, we report that the lin-4 microRNA can regulate the transition between branch formation and synaptogenesis in the PLM axon of C. elegans. The PLM axon grows a collateral branch during the early L1 stage and undergoes synaptogenesis during the late L1 stage. Loss of the lin-4 microRNA disrupts synaptogenesis during the late L1 stage, suggesting that lin-4 promotes synaptogenesis. Conversely, the target of lin-4, the LIN-14 transcription factor, promotes PLM branch formation and inhibits synaptogenesis during the early L1 stage. Moreover, we present genetic evidence suggesting that synaptic vesicle transport is required for PLM branch formation and that the role of LIN-14 is to promote transport of synaptic vesicles to the region of future branch growth. These observations provide a novel mechanism whereby lin-4 promotes the transition from branch formation to synaptogenesis by repressing the branch-promoting and synaptogenesis-inhibiting activities of LIN-14.
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Affiliation(s)
- Yan Xu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Christopher C Quinn
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
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36
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Chisholm AD, Hutter H, Jin Y, Wadsworth WG. The Genetics of Axon Guidance and Axon Regeneration in Caenorhabditis elegans. Genetics 2016; 204:849-882. [PMID: 28114100 PMCID: PMC5105865 DOI: 10.1534/genetics.115.186262] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022] Open
Abstract
The correct wiring of neuronal circuits depends on outgrowth and guidance of neuronal processes during development. In the past two decades, great progress has been made in understanding the molecular basis of axon outgrowth and guidance. Genetic analysis in Caenorhabditis elegans has played a key role in elucidating conserved pathways regulating axon guidance, including Netrin signaling, the slit Slit/Robo pathway, Wnt signaling, and others. Axon guidance factors were first identified by screens for mutations affecting animal behavior, and by direct visual screens for axon guidance defects. Genetic analysis of these pathways has revealed the complex and combinatorial nature of guidance cues, and has delineated how cues guide growth cones via receptor activity and cytoskeletal rearrangement. Several axon guidance pathways also affect directed migrations of non-neuronal cells in C. elegans, with implications for normal and pathological cell migrations in situations such as tumor metastasis. The small number of neurons and highly stereotyped axonal architecture of the C. elegans nervous system allow analysis of axon guidance at the level of single identified axons, and permit in vivo tests of prevailing models of axon guidance. C. elegans axons also have a robust capacity to undergo regenerative regrowth after precise laser injury (axotomy). Although such axon regrowth shares some similarities with developmental axon outgrowth, screens for regrowth mutants have revealed regeneration-specific pathways and factors that were not identified in developmental screens. Several areas remain poorly understood, including how major axon tracts are formed in the embryo, and the function of axon regeneration in the natural environment.
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Affiliation(s)
| | - Harald Hutter
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, and
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
- Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, Chevy Chase, Maryland, and
| | - William G Wadsworth
- Department of Pathology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
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Jang S, Nelson JC, Bend EG, Rodríguez-Laureano L, Tueros FG, Cartagenova L, Underwood K, Jorgensen EM, Colón-Ramos DA. Glycolytic Enzymes Localize to Synapses under Energy Stress to Support Synaptic Function. Neuron 2016; 90:278-91. [PMID: 27068791 DOI: 10.1016/j.neuron.2016.03.011] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 01/12/2016] [Accepted: 03/08/2016] [Indexed: 01/07/2023]
Abstract
Changes in neuronal activity create local and transient changes in energy demands at synapses. Here we discover a metabolic compartment that forms in vivo near synapses to meet local energy demands and support synaptic function in Caenorhabditis elegans neurons. Under conditions of energy stress, glycolytic enzymes redistribute from a diffuse localization in the cytoplasm to a punctate localization adjacent to synapses. Glycolytic enzymes colocalize, suggesting the ad hoc formation of a glycolysis compartment, or a "glycolytic metabolon," that can maintain local levels of ATP. Local formation of the glycolytic metabolon is dependent on presynaptic scaffolding proteins, and disruption of the glycolytic metabolon blocks the synaptic vesicle cycle, impairs synaptic recovery, and affects locomotion. Our studies indicate that under energy stress conditions, energy demands in C. elegans synapses are met locally through the assembly of a glycolytic metabolon to sustain synaptic function and behavior. VIDEO ABSTRACT.
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Affiliation(s)
- SoRi Jang
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology and Department of Neuroscience, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA
| | - Jessica C Nelson
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology and Department of Neuroscience, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA
| | - Eric G Bend
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Lucelenie Rodríguez-Laureano
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology and Department of Neuroscience, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA
| | - Felipe G Tueros
- Laboratorio de Microbiología, Facultad de Ciencias Biológicas, Universidad Ricardo Palma, P.O. Box 1801, Lima 33, Perú
| | - Luis Cartagenova
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology and Department of Neuroscience, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA
| | - Katherine Underwood
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology and Department of Neuroscience, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA
| | - Erik M Jorgensen
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Daniel A Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology and Department of Neuroscience, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06536-0812, USA; Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico, 201 Boulevard del Valle, San Juan 00901, Puerto Rico.
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Yung YL, Cheung MY, Miao R, Fong YH, Li KP, Yu MH, Chye ML, Wong KB, Lam HM. Site-directed Mutagenesis Shows the Significance of Interactions with Phospholipids and the G-protein OsYchF1 for the Physiological Functions of the Rice GTPase-activating Protein 1 (OsGAP1). J Biol Chem 2015; 290:23984-96. [PMID: 26286751 PMCID: PMC4583037 DOI: 10.1074/jbc.m115.655639] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 08/17/2015] [Indexed: 11/06/2022] Open
Abstract
The C2 domain is one of the most diverse phospholipid-binding domains mediating cellular signaling. One group of C2-domain proteins are plant-specific and are characterized by their small sizes and simple structures. We have previously reported that a member of this group, OsGAP1, is able to alleviate salt stress and stimulate defense responses, and bind to both phospholipids and an unconventional G-protein, OsYchF1. Here we solved the crystal structure of OsGAP1 to a resolution of 1.63 Å. Using site-directed mutagenesis, we successfully differentiated between the clusters of surface residues that are required for binding to phospholipids versus OsYchF1, which, in turn, is critical for its role in stimulating defense responses. On the other hand, the ability to alleviate salt stress by OsGAP1 is dependent only on its ability to bind OsYchF1 and is independent of its phospholipid-binding activity.
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Affiliation(s)
- Yuk-Lin Yung
- From the School of Life Sciences, Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology, and
| | - Ming-Yan Cheung
- From the School of Life Sciences, Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology, and
| | - Rui Miao
- From the School of Life Sciences, Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology, and the School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Yu-Hang Fong
- From the School of Life Sciences, Center for Protein Sciences and Crystallography, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China and
| | - Kwan-Pok Li
- From the School of Life Sciences, Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology, and
| | - Mei-Hui Yu
- From the School of Life Sciences, Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology, and
| | - Mee-Len Chye
- the School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Kam-Bo Wong
- From the School of Life Sciences, Center for Protein Sciences and Crystallography, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China and
| | - Hon-Ming Lam
- From the School of Life Sciences, Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology, and
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39
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Edwards SL, Yorks RM, Morrison LM, Hoover CM, Miller KG. Synapse-Assembly Proteins Maintain Synaptic Vesicle Cluster Stability and Regulate Synaptic Vesicle Transport in Caenorhabditis elegans. Genetics 2015; 201:91-116. [PMID: 26354975 PMCID: PMC4566279 DOI: 10.1534/genetics.115.177337] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/17/2015] [Indexed: 11/18/2022] Open
Abstract
The functional integrity of neurons requires the bidirectional active transport of synaptic vesicles (SVs) in axons. The kinesin motor KIF1A transports SVs from somas to stable SV clusters at synapses, while dynein moves them in the opposite direction. However, it is unclear how SV transport is regulated and how SVs at clusters interact with motor proteins. We addressed these questions by isolating a rare temperature-sensitive allele of Caenorhabditis elegans unc-104 (KIF1A) that allowed us to manipulate SV levels in axons and dendrites. Growth at 20° and 14° resulted in locomotion rates that were ∼3 and 50% of wild type, respectively, with similar effects on axonal SV levels. Corresponding with the loss of SVs from axons, mutants grown at 14° and 20° showed a 10- and 24-fold dynein-dependent accumulation of SVs in their dendrites. Mutants grown at 14° and switched to 25° showed an abrupt irreversible 50% decrease in locomotion and a 50% loss of SVs from the synaptic region 12-hr post-shift, with no further decreases at later time points, suggesting that the remaining clustered SVs are stable and resistant to retrograde removal by dynein. The data further showed that the synapse-assembly proteins SYD-1, SYD-2, and SAD-1 protected SV clusters from degradation by motor proteins. In syd-1, syd-2, and sad-1 mutants, SVs accumulate in an UNC-104-dependent manner in the distal axon region that normally lacks SVs. In addition to their roles in SV cluster stability, all three proteins also regulate SV transport.
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Affiliation(s)
- Stacey L Edwards
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Rosalina M Yorks
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Logan M Morrison
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Christopher M Hoover
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Kenneth G Miller
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
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40
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Edwards SL, Morrison LM, Yorks RM, Hoover CM, Boominathan S, Miller KG. UNC-16 (JIP3) Acts Through Synapse-Assembly Proteins to Inhibit the Active Transport of Cell Soma Organelles to Caenorhabditis elegans Motor Neuron Axons. Genetics 2015; 201:117-41. [PMID: 26354976 PMCID: PMC4566257 DOI: 10.1534/genetics.115.177345] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/24/2015] [Indexed: 12/31/2022] Open
Abstract
The conserved protein UNC-16 (JIP3) inhibits the active transport of some cell soma organelles, such as lysosomes, early endosomes, and Golgi, to the synaptic region of axons. However, little is known about UNC-16's organelle transport regulatory function, which is distinct from its Kinesin-1 adaptor function. We used an unc-16 suppressor screen in Caenorhabditis elegans to discover that UNC-16 acts through CDK-5 (Cdk5) and two conserved synapse assembly proteins: SAD-1 (SAD-A Kinase), and SYD-2 (Liprin-α). Genetic analysis of all combinations of double and triple mutants in unc-16(+) and unc-16(-) backgrounds showed that the three proteins (CDK-5, SAD-1, and SYD-2) are all part of the same organelle transport regulatory system, which we named the CSS system based on its founder proteins. Further genetic analysis revealed roles for SYD-1 (another synapse assembly protein) and STRADα (a SAD-1-interacting protein) in the CSS system. In an unc-16(-) background, loss of the CSS system improved the sluggish locomotion of unc-16 mutants, inhibited axonal lysosome accumulation, and led to the dynein-dependent accumulation of lysosomes in dendrites. Time-lapse imaging of lysosomes in CSS system mutants in unc-16(+) and unc-16(-) backgrounds revealed active transport defects consistent with the steady-state distributions of lysosomes. UNC-16 also uses the CSS system to regulate the distribution of early endosomes in neurons and, to a lesser extent, Golgi. The data reveal a new and unprecedented role for synapse assembly proteins, acting as part of the newly defined CSS system, in mediating UNC-16's organelle transport regulatory function.
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Affiliation(s)
- Stacey L Edwards
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Logan M Morrison
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Rosalina M Yorks
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Christopher M Hoover
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Soorajnath Boominathan
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Kenneth G Miller
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
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41
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Siebert M, Böhme MA, Driller JH, Babikir H, Mampell MM, Rey U, Ramesh N, Matkovic T, Holton N, Reddy-Alla S, Göttfert F, Kamin D, Quentin C, Klinedinst S, Andlauer TF, Hell SW, Collins CA, Wahl MC, Loll B, Sigrist SJ. A high affinity RIM-binding protein/Aplip1 interaction prevents the formation of ectopic axonal active zones. eLife 2015; 4. [PMID: 26274777 PMCID: PMC4536467 DOI: 10.7554/elife.06935] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 07/24/2015] [Indexed: 12/17/2022] Open
Abstract
Synaptic vesicles (SVs) fuse at active zones (AZs) covered by a protein scaffold, at Drosophila synapses comprised of ELKS family member Bruchpilot (BRP) and RIM-binding protein (RBP). We here demonstrate axonal co-transport of BRP and RBP using intravital live imaging, with both proteins co-accumulating in axonal aggregates of several transport mutants. RBP, via its C-terminal Src-homology 3 (SH3) domains, binds Aplip1/JIP1, a transport adaptor involved in kinesin-dependent SV transport. We show in atomic detail that RBP C-terminal SH3 domains bind a proline-rich (PxxP) motif of Aplip1/JIP1 with submicromolar affinity. Pointmutating this PxxP motif provoked formation of ectopic AZ-like structures at axonal membranes. Direct interactions between AZ proteins and transport adaptors seem to provide complex avidity and shield synaptic interaction surfaces of pre-assembled scaffold protein transport complexes, thus, favouring physiological synaptic AZ assembly over premature assembly at axonal membranes. DOI:http://dx.doi.org/10.7554/eLife.06935.001 To pass on information, the neurons that make up the nervous system connect at structures known as synapses. Chemical messengers called neurotransmitters are released from one neuron, and travel across the synapse to trigger a response in the neighbouring cell. The formation of new synapses plays an important role in learning and memory, but many aspects of this process are not well understood. In a specific region of the synapse called the active zone, a scaffold of proteins helps to release the neurotransmitters. These proteins are made in the cell body of the neuron, and are then transported to the end of the long, thin axons that protrude from the cell body. This presents a challenge for the cell, because the components of the active zone scaffold must be correctly targeted to the synapse at the end of the axon, ensuring the active zone scaffold assembles only at its proper location. Siebert, Böhme et al. studied how some of the proteins that are found in the active zone scaffold of the fruit fly Drosophila are transported along axons. Labelling the proteins with fluorescent markers allowed their movement to be examined under a microscope in living Drosophila larvae. The results showed that two of the proteins—known as BRP and RBP—are transported along the axons together. Further investigation revealed that a transport adaptor protein called Aplip1, which binds to RBP, is required for this movement. Siebert, Böhme et al. established the structure of the part of RBP where this interaction occurs, and found that mutating this region causes premature active zone scaffold assembly in the axonal part of the neuron. The interaction between RBP and Aplip1 is very strong, and this helps to prevent the scaffold assembling before it has reached the correct part of the neuron. Exactly how the transport adaptor and active zone protein are separated once they reach their final destination (the synapse) remains to be discovered. DOI:http://dx.doi.org/10.7554/eLife.06935.002
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Affiliation(s)
- Matthias Siebert
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Mathias A Böhme
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Jan H Driller
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Husam Babikir
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Malou M Mampell
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Ulises Rey
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Niraja Ramesh
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Tanja Matkovic
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Nicole Holton
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Suneel Reddy-Alla
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Fabian Göttfert
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dirk Kamin
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christine Quentin
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Susan Klinedinst
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Till Fm Andlauer
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Stefan W Hell
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Catherine A Collins
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Markus C Wahl
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Bernhard Loll
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Stephan J Sigrist
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
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42
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Transcriptional coordination of synaptogenesis and neurotransmitter signaling. Curr Biol 2015; 25:1282-95. [PMID: 25913400 DOI: 10.1016/j.cub.2015.03.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 02/10/2015] [Accepted: 03/18/2015] [Indexed: 11/21/2022]
Abstract
During nervous system development, postmitotic neurons face the challenge of generating and structurally organizing specific synapses with appropriate synaptic partners. An important unexplored question is whether the process of synaptogenesis is coordinated with the adoption of specific signaling properties of a neuron. Such signaling properties are defined by the neurotransmitter system that a neuron uses to communicate with postsynaptic partners, the neurotransmitter receptor type used to receive input from presynaptic neurons, and, potentially, other sensory receptors that activate a neuron. Elucidating the mechanisms that coordinate synaptogenesis, neuronal activation, and neurotransmitter signaling in a postmitotic neuron represents one key approach to understanding how neurons develop as functional units. Using the SAB class of Caenorhabditis elegans motor neurons as a model system, we show here that the phylogenetically conserved COE-type transcription factor UNC-3 is required for synaptogenesis. UNC-3 directly controls the expression of the ADAMTS-like protein MADD-4/Punctin, a presynaptically secreted synapse-organizing molecule that clusters postsynaptic receptors. UNC-3 also controls the assembly of presynaptic specializations and ensures the coordinated expression of enzymes and transporters that define the cholinergic neurotransmitter identity of the SAB neurons. Furthermore, synaptic output properties of the SAB neurons are coordinated with neuronal activation and synaptic input, as evidenced by UNC-3 also regulating the expression of ionotropic neurotransmitter receptors and putative stretch receptors. Our study shows how synaptogenesis and distinct, function-defining signaling features of a postmitotic neuron are hardwired together through coordinated transcriptional control.
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43
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Xu Y, Taru H, Jin Y, Quinn CC. SYD-1C, UNC-40 (DCC) and SAX-3 (Robo) function interdependently to promote axon guidance by regulating the MIG-2 GTPase. PLoS Genet 2015; 11:e1005185. [PMID: 25876065 PMCID: PMC4398414 DOI: 10.1371/journal.pgen.1005185] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 03/30/2015] [Indexed: 12/13/2022] Open
Abstract
During development, axons must integrate directional information encoded by multiple guidance cues and their receptors. Axon guidance receptors, such as UNC-40 (DCC) and SAX-3 (Robo), can function individually or combinatorially with other guidance receptors to regulate downstream effectors. However, little is known about the molecular mechanisms that mediate combinatorial guidance receptor signaling. Here, we show that UNC-40, SAX-3 and the SYD-1 RhoGAP-like protein function interdependently to regulate the MIG-2 (Rac) GTPase in the HSN axon of C. elegans. We find that SYD-1 mediates an UNC-6 (netrin) independent UNC-40 activity to promote ventral axon guidance. Genetic analysis suggests that SYD-1 function in axon guidance requires both UNC-40 and SAX-3 activity. Moreover, the cytoplasmic domains of UNC-40 and SAX-3 bind to SYD-1 and SYD-1 binds to and negatively regulates the MIG-2 (Rac) GTPase. We also find that the function of SYD-1 in axon guidance is mediated by its phylogenetically conserved C isoform, indicating that the role of SYD-1 in guidance is distinct from its previously described roles in synaptogenesis and axonal specification. Our observations reveal a molecular mechanism that can allow two guidance receptors to function interdependently to regulate a common downstream effector, providing a potential means for the integration of guidance signals.
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Affiliation(s)
- Yan Xu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America
| | - Hidenori Taru
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Yishi Jin
- Division of Biological Sciences, Section of Neurobiology, and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California, United States of America
| | - Christopher C. Quinn
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America
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Systematic analyses of rpm-1 suppressors reveal roles for ESS-2 in mRNA splicing in Caenorhabditis elegans. Genetics 2014; 198:1101-15. [PMID: 25194163 DOI: 10.1534/genetics.114.167841] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The PHR (Pam/Highwire/RPM-1) family of ubiquitin E3 ligases plays conserved roles in axon patterning and synaptic development. Genetic modifier analysis has greatly aided the discovery of the signal transduction cascades regulated by these proteins. In Caenorhabditis elegans, loss of function in rpm-1 causes axon overgrowth and aberrant presynaptic morphology, yet the mutant animals exhibit little behavioral deficits. Strikingly, rpm-1 mutations strongly synergize with loss of function in the presynaptic active zone assembly factors, syd-1 and syd-2, resulting in severe locomotor deficits. Here, we provide ultrastructural evidence that double mutants, between rpm-1 and syd-1 or syd-2, dramatically impair synapse formation. Taking advantage of the synthetic locomotor defects to select for genetic suppressors, previous studies have identified the DLK-1 MAP kinase cascade negatively regulated by RPM-1. We now report a comprehensive analysis of a large number of suppressor mutations of this screen. Our results highlight the functional specificity of the DLK-1 cascade in synaptogenesis. We also identified two previously uncharacterized genes. One encodes a novel protein, SUPR-1, that acts cell autonomously to antagonize RPM-1. The other affects a conserved protein ESS-2, the homolog of human ES2 or DGCR14. Loss of function in ess-2 suppresses rpm-1 only in the presence of a dlk-1 splice acceptor mutation. We show that ESS-2 acts to promote accurate mRNA splicing when the splice site is compromised. The human DGCR14/ES2 resides in a deleted chromosomal region implicated in DiGeorge syndrome, and its mutation has shown high probability as a risk factor for schizophrenia. Our findings provide the first functional evidence that this family of proteins regulate mRNA splicing in a context-specific manner.
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Drosophila Syd-1, liprin-α, and protein phosphatase 2A B' subunit Wrd function in a linear pathway to prevent ectopic accumulation of synaptic materials in distal axons. J Neurosci 2014; 34:8474-87. [PMID: 24948803 DOI: 10.1523/jneurosci.0409-14.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
During synaptic development, presynaptic differentiation occurs as an intrinsic property of axons to form specialized areas of plasma membrane [active zones (AZs)] that regulate exocytosis and endocytosis of synaptic vesicles. Genetic and biochemical studies in vertebrate and invertebrate model systems have identified a number of proteins involved in AZ assembly. However, elucidating the molecular events of AZ assembly in a spatiotemporal manner remains a challenge. Syd-1 (synapse defective-1) and Liprin-α have been identified as two master organizers of AZ assembly. Genetic and imaging analyses in invertebrates show that Syd-1 works upstream of Liprin-α in synaptic assembly through undefined mechanisms. To understand molecular pathways downstream of Liprin-α, we performed a proteomic screen of Liprin-α-interacting proteins in Drosophila brains. We identify Drosophila protein phosphatase 2A (PP2A) regulatory subunit B' [Wrd (Well Rounded)] as a Liprin-α-interacting protein, and we demonstrate that it mediates the interaction of Liprin-α with PP2A holoenzyme and the Liprin-α-dependent synaptic localization of PP2A. Interestingly, loss of function in syd-1, liprin-α, or wrd shares a common defect in which a portion of synaptic vesicles, dense-core vesicles, and presynaptic cytomatrix proteins ectopically accumulate at the distal, but not proximal, region of motoneuron axons. Strong genetic data show that a linear syd-1/liprin-α/wrd pathway in the motoneuron antagonizes glycogen synthase kinase-3β kinase activity to prevent the ectopic accumulation of synaptic materials. Furthermore, we provide data suggesting that the syd-1/liprin-α/wrd pathway stabilizes AZ specification at the nerve terminal and that such a novel function is independent of the roles of syd-1/liprin-α in regulating the morphology of the T-bar structural protein BRP (Bruchpilot).
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Kittelmann M, Hegermann J, Goncharov A, Taru H, Ellisman MH, Richmond JE, Jin Y, Eimer S. Liprin-α/SYD-2 determines the size of dense projections in presynaptic active zones in C. elegans. J Cell Biol 2013; 203:849-63. [PMID: 24322429 PMCID: PMC3857474 DOI: 10.1083/jcb.201302022] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 11/06/2013] [Indexed: 01/23/2023] Open
Abstract
Synaptic vesicle (SV) release is spatially and temporally regulated by a network of proteins that form the presynaptic active zone (AZ). The hallmark of most AZs is an electron-dense projection (DP) surrounded by SVs. Despite their importance for our understanding of triggered SV release, high-resolution analyses of DP structures are limited. Using electron microscopy, we show that DPs at Caenorhabditis elegans neuromuscular junctions (NMJs) were highly structured, composed of building units forming bays in which SVs are docked to the AZ membrane. Furthermore, larger ribbonlike DPs that were multimers of the NMJ building unit are found at synapses between inter- and motoneurons. We also demonstrate that DP size is determined by the activity of the AZ protein SYD-2/Liprin-α. Whereas loss of syd-2 function led to smaller DPs, syd-2 gain-of-function mutants displayed larger ribbonlike DPs through increased recruitment of ELKS-1/ELKS. Therefore, our data suggest that a main role of SYD-2/Liprin-α in synaptogenesis is to regulate the polymerization of DPs.
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Affiliation(s)
- Maike Kittelmann
- European Neuroscience Institute, 37077 Göttingen, Germany
- Cellular Neurobiology, Schwann-Schleiden-Centre for Molecular Cell Biology, 37077 Göttingen, Germany
| | - Jan Hegermann
- European Neuroscience Institute, 37077 Göttingen, Germany
- Center for Molecular Physiology of the Brain, 37073 Göttingen, Germany
- Institute of Functional and Applied Anatomy, Hannover Medical School, 30625 Hannover, Germany
| | - Alexandr Goncharov
- Howard Hughes Medical Institute, Division of Biological Sciences; and Center for Research on Biological Systems, National Center for Microscopy and Imaging Research and Department of Neurosciences; University of California, San Diego, La Jolla, CA 92093
| | - Hidenori Taru
- Howard Hughes Medical Institute, Division of Biological Sciences; and Center for Research on Biological Systems, National Center for Microscopy and Imaging Research and Department of Neurosciences; University of California, San Diego, La Jolla, CA 92093
- Laboratory of Neuronal Cell Biology, Graduate School of Pharmaceutical Sciences and Creative Research Institute, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan
| | - Mark H. Ellisman
- Howard Hughes Medical Institute, Division of Biological Sciences; and Center for Research on Biological Systems, National Center for Microscopy and Imaging Research and Department of Neurosciences; University of California, San Diego, La Jolla, CA 92093
| | - Janet E. Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
| | - Yishi Jin
- Howard Hughes Medical Institute, Division of Biological Sciences; and Center for Research on Biological Systems, National Center for Microscopy and Imaging Research and Department of Neurosciences; University of California, San Diego, La Jolla, CA 92093
| | - Stefan Eimer
- European Neuroscience Institute, 37077 Göttingen, Germany
- Center for Molecular Physiology of the Brain, 37073 Göttingen, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79108 Freiburg, Germany
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Wentzel C, Sommer JE, Nair R, Stiefvater A, Sibarita JB, Scheiffele P. mSYD1A, a mammalian synapse-defective-1 protein, regulates synaptogenic signaling and vesicle docking. Neuron 2013; 78:1012-23. [PMID: 23791195 DOI: 10.1016/j.neuron.2013.05.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2013] [Indexed: 10/26/2022]
Abstract
Structure and function of presynaptic terminals are critical for the transmission and processing of neuronal signals. Trans-synaptic signaling systems instruct the differentiation and function of presynaptic release sites, but their downstream mediators are only beginning to be understood. Here, we identify the intracellular mSYD1A (mouse Synapse-Defective-1A) as a regulator of presynaptic function in mice. mSYD1A forms a complex with presynaptic receptor tyrosine phosphatases and controls tethering of synaptic vesicles at synapses. mSYD1A function relies on an intrinsically disordered domain that interacts with multiple structurally unrelated binding partners, including the active zone protein liprin-α2 and nsec1/munc18-1. In mSYD1A knockout mice, synapses assemble in normal numbers but there is a significant reduction in synaptic vesicle docking at the active zone and an impairment of synaptic transmission. Thus, mSYD1A is a regulator of presynaptic release sites at central synapses.
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Protein tyrosine phosphatases PTPδ, PTPσ, and LAR: presynaptic hubs for synapse organization. Trends Neurosci 2013; 36:522-34. [PMID: 23835198 DOI: 10.1016/j.tins.2013.06.002] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/03/2013] [Accepted: 06/11/2013] [Indexed: 02/04/2023]
Abstract
Synapse development requires differentiation of presynaptic neurotransmitter release sites and postsynaptic receptive apparatus coordinated by synapse organizing proteins. In addition to the well-characterized neurexins, recent studies identified presynaptic type IIa receptor-type protein tyrosine phosphatases (RPTPs) as mediators of presynaptic differentiation and triggers of postsynaptic differentiation, thus extending the roles of RPTPs from axon outgrowth and guidance. Similarly to neurexins, RPTPs exist in multiple isoforms generated by alternative splicing that interact in a splice-selective code with diverse postsynaptic partners. The parallel RPTP and neurexin hub design facilitates synapse self-assembly through cooperation, pairs presynaptic similarity with postsynaptic diversity, and balances excitation with inhibition. Upon mutation of individual genes in neuropsychiatric disorders, imbalance of this synaptic organizing network may contribute to impaired cognitive function.
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Chia PH, Patel MR, Wagner OI, Klopfenstein DR, Shen K. Intramolecular regulation of presynaptic scaffold protein SYD-2/liprin-α. Mol Cell Neurosci 2013; 56:76-84. [PMID: 23541703 PMCID: PMC3930023 DOI: 10.1016/j.mcn.2013.03.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 11/27/2022] Open
Abstract
SYD-2/liprin-α is a multi-domain protein that associates with and recruits multiple active zone molecules to form presynaptic specializations. Given SYD-2's critical role in synapse formation, its synaptogenic ability is likely tightly regulated. However, mechanisms that regulate SYD-2 function are poorly understood. In this study, we provide evidence that SYD-2's function may be regulated by interactions between its coiled-coil (CC) domains and sterile α-motif (SAM) domains. We show that the N-terminal CC domains are necessary and sufficient to assemble functional synapses while C-terminal SAM domains are not, suggesting that the CC domains are responsible for the synaptogenic activity of SYD-2. Surprisingly, syd-2 alleles with single amino acid mutations in the SAM domain show strong loss of function phenotypes, suggesting that SAM domains also play an important role in SYD-2's function. A previously characterized syd-2 gain-of-function mutation within the CC domains is epistatic to the loss-of-function mutations in the SAM domain. In addition, yeast two-hybrid analysis showed interactions between the CC and SAM domains. Thus, the data is consistent with a model where the SAM domains regulate the CC domain-dependent synaptogenic activity of SYD-2. Taken together, our study provides new mechanistic insights into how SYD-2's activity may be modulated to regulate synapse formation during development.
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Affiliation(s)
- Poh Hui Chia
- Howard Hughes Medical Institute, Department of Biology, Stanford University, 385 Serra Mall, Stanford, CA 94305, United States; Neurosciences Program, Stanford University, 385 Serra Mall, Stanford, CA 94305, United States
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Abstract
Genetic analyses in both worm and fly have identified the RhoGAP-like protein Syd-1 as a key positive regulator of presynaptic assembly. In worm, loss of syd-1 can be fully rescued by overexpressing wild-type Liprin-α, suggesting that the primary function of Syd-1 in this process is to recruit Liprin-α. We show that loss of syd-1 from Drosophila R7 photoreceptors causes two morphological defects that occur at distinct developmental time points. First, syd-1 mutant R7 axons often fail to form terminal boutons in their normal M6 target layer. Later, those mutant axons that do contact M6 often project thin extensions beyond it. We find that the earlier defect coincides with a failure to localize synaptic vesicles, suggesting that it reflects a failure in presynaptic assembly. We then analyze the relationship between syd-1 and Liprin-α in R7s. We find that loss of Liprin-α causes a stronger early R7 defect and provide a possible explanation for this disparity: we show that Liprin-α promotes Kinesin-3/Unc-104/Imac-mediated axon transport independently of Syd-1 and that Kinesin-3/Unc-104/Imac is required for normal R7 bouton formation. Unlike loss of syd-1, loss of Liprin-α does not cause late R7 extensions. We show that overexpressing Liprin-α partly rescues the early but not the late syd-1 mutant R7 defect. We therefore conclude that the two defects are caused by distinct molecular mechanisms. We find that Trio overexpression rescues both syd-1 defects and that trio and syd-1 have similar loss- and gain-of-function phenotypes, suggesting that the primary function of Syd-1 in R7s may be to promote Trio activity.
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