1
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Oevel K, Hohensee S, Kumar A, Rosas-Brugada I, Bartolini F, Soykan T, Haucke V. Rho GTPase signaling and mDia facilitate endocytosis via presynaptic actin. eLife 2024; 12:RP92755. [PMID: 38502163 PMCID: PMC10950329 DOI: 10.7554/elife.92755] [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] [Indexed: 03/20/2024] Open
Abstract
Neurotransmission at synapses is mediated by the fusion and subsequent endocytosis of synaptic vesicle membranes. Actin has been suggested to be required for presynaptic endocytosis but the mechanisms that control actin polymerization and its mode of action within presynaptic nerve terminals remain poorly understood. We combine optical recordings of presynaptic membrane dynamics and ultrastructural analysis with genetic and pharmacological manipulations to demonstrate that presynaptic endocytosis is controlled by actin regulatory diaphanous-related formins mDia1/3 and Rho family GTPase signaling in mouse hippocampal neurons. We show that impaired presynaptic actin assembly in the near absence of mDia1/3 and reduced RhoA activity is partly compensated by hyperactivation of Rac1. Inhibition of Rac1 signaling further aggravates impaired presynaptic endocytosis elicited by loss of mDia1/3. Our data suggest that interdependent mDia1/3-Rho and Rac1 signaling pathways cooperatively act to facilitate synaptic vesicle endocytosis by controlling presynaptic F-actin.
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Affiliation(s)
- Kristine Oevel
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Svea Hohensee
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Atul Kumar
- Department of Pathology and Cell Biology, Columbia University Medical CenterNew York CityUnited States
| | | | - Francesca Bartolini
- Department of Pathology and Cell Biology, Columbia University Medical CenterNew York CityUnited States
| | - Tolga Soykan
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität BerlinBerlinGermany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin BerlinBerlinGermany
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2
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Bingham D, Jakobs CE, Wernert F, Boroni-Rueda F, Jullien N, Schentarra EM, Friedl K, Da Costa Moura J, van Bommel DM, Caillol G, Ogawa Y, Papandréou MJ, Leterrier C. Presynapses contain distinct actin nanostructures. J Cell Biol 2023; 222:e202208110. [PMID: 37578754 PMCID: PMC10424573 DOI: 10.1083/jcb.202208110] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 06/07/2023] [Accepted: 07/25/2023] [Indexed: 08/15/2023] Open
Abstract
The architecture of the actin cytoskeleton that concentrates at presynapses remains poorly known, hindering our understanding of its roles in synaptic physiology. In this work, we measure and visualize presynaptic actin by diffraction-limited and super-resolution microscopy, thanks to a validated model of bead-induced presynapses in cultured neurons. We identify a major population of actin-enriched presynapses that concentrates more presynaptic components and shows higher synaptic vesicle cycling than their non-enriched counterparts. Pharmacological perturbations point to an optimal actin amount and the presence of distinct actin structures within presynapses. We directly visualize these nanostructures using Single Molecule Localization Microscopy (SMLM), defining three distinct types: an actin mesh at the active zone, actin rails between the active zone and deeper reserve pools, and actin corrals around the whole presynaptic compartment. Finally, CRISPR-tagging of endogenous actin allows us to validate our results in natural synapses between cultured neurons, confirming the role of actin enrichment and the presence of three types of presynaptic actin nanostructures.
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Affiliation(s)
- Dominic Bingham
- CNRS, INP UMR7051, NeuroCyto, Aix Marseille Université, Marseille, France
| | | | - Florian Wernert
- CNRS, INP UMR7051, NeuroCyto, Aix Marseille Université, Marseille, France
| | - Fanny Boroni-Rueda
- CNRS, INP UMR7051, NeuroCyto, Aix Marseille Université, Marseille, France
| | - Nicolas Jullien
- CNRS, INP UMR7051, NeuroCyto, Aix Marseille Université, Marseille, France
| | | | - Karoline Friedl
- CNRS, INP UMR7051, NeuroCyto, Aix Marseille Université, Marseille, France
- Abbelight, Cachan, France
| | | | | | - Ghislaine Caillol
- CNRS, INP UMR7051, NeuroCyto, Aix Marseille Université, Marseille, France
| | - Yuki Ogawa
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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3
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Smith JD, Brawley J, Bordenave KC, Olsen RK, Intasiri A, Cremo CR, Bell TW. Isoform selectivities of novel 4-hydroxycoumarin imines as inhibitors of myosin II. Eur J Med Chem 2023; 247:115008. [PMID: 36543032 PMCID: PMC9889102 DOI: 10.1016/j.ejmech.2022.115008] [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: 10/28/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Muscle myosin inhibition could be used to treat many medical conditions involving hypercontractile states, including muscle spasticity, chronic musculoskeletal pain, and hypertrophic cardiomyopathy. A series of 13 advanced analogs of 3-(N-butylethanimidoyl)ethyl)-4-hydroxy-2H-chromen-2-one (BHC) were synthesized to explore extended imine nitrogen side chains and compare aldimines vs. ketimines. None of the new analogs inhibit nonmuscle myosin in a cytokinesis assay. ATPase structure-activity relationships reveal that selectivity for cardiac vs. skeletal myosin can be tuned with subtle structural changes. None of the compounds inhibited smooth muscle myosin II. Docking the compounds to homology models of cardiac and skeletal myosin II gave rationales for the effects of side arm length on inhibition selectivity and for cardiac vs. skeletal myosin. Properties including solubility, stability and toxicity, suggest that certain BHC analogs may be useful as candidates for preclinical studies or as lead compounds for advanced candidates for drugs with cardiac or skeletal muscle myosin selectivity.
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Affiliation(s)
- Joshua D Smith
- Department of Pharmacology, University of Nevada, School of Medicine, Reno, NV, 89557-0318, USA
| | - Jhonnathan Brawley
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA
| | - Kate C Bordenave
- Department of Pharmacology, University of Nevada, School of Medicine, Reno, NV, 89557-0318, USA
| | - Ryan K Olsen
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA
| | - Amarawan Intasiri
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA
| | - Christine R Cremo
- Department of Pharmacology, University of Nevada, School of Medicine, Reno, NV, 89557-0318, USA.
| | - Thomas W Bell
- Department of Chemistry, University of Nevada, Reno, NV, 89557-0216, USA.
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4
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Pseudokinase NRP1 facilitates endocytosis of transferrin in the African trypanosome. Sci Rep 2022; 12:18572. [PMID: 36329148 PMCID: PMC9633767 DOI: 10.1038/s41598-022-22054-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
Trypanosoma brucei causes human African trypanosomiasis (HAT) and nagana in cattle. During infection of a vertebrate, endocytosis of host transferrin (Tf) is important for viability of the parasite. The majority of proteins involved in trypanosome endocytosis of Tf are unknown. Here we identify pseudokinase NRP1 (Tb427tmp.160.4770) as a regulator of Tf endocytosis. Genetic knockdown of NRP1 inhibited endocytosis of Tf without blocking uptake of bovine serum albumin. Binding of Tf to the flagellar pocket was not affected by knockdown of NRP1. However the quantity of Tf per endosome dropped significantly, consistent with NRP1 promoting robust capture and/or retention of Tf in vesicles. NRP1 is involved in motility of Tf-laden vesicles since distances between endosomes and the kinetoplast were reduced after knockdown of the gene. In search of possible mediators of NRP1 modulation of Tf endocytosis, the gene was knocked down and the phosphoproteome analyzed. Phosphorylation of protein kinases forkhead, NEK6, and MAPK10 was altered, in addition to EpsinR, synaptobrevin and other vesicle-associated proteins predicted to be involved in endocytosis. These candidate proteins may link NRP1 functionally either to protein kinases or to vesicle-associated proteins.
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5
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Wu LG, Chan CY. Multiple Roles of Actin in Exo- and Endocytosis. Front Synaptic Neurosci 2022; 14:841704. [PMID: 35308832 PMCID: PMC8931529 DOI: 10.3389/fnsyn.2022.841704] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Cytoskeletal filamentous actin (F-actin) has long been considered a molecule that may regulate exo- and endocytosis. However, its exact roles remained elusive. Recent studies shed new light on many crucial roles of F-actin in regulating exo- and endocytosis. Here, this progress is reviewed from studies of secretory cells, particularly neurons and endocrine cells. These studies reveal that F-actin is involved in mediating all kinetically distinguishable forms of endocytosis, including ultrafast, fast, slow, bulk, and overshoot endocytosis, likely via membrane pit formation. F-actin promotes vesicle replenishment to the readily releasable pool most likely via active zone clearance, which may sustain synaptic transmission and overcome short-term depression of synaptic transmission during repetitive firing. By enhancing plasma membrane tension, F-actin promotes fusion pore expansion, vesicular content release, and a fusion mode called shrink fusion involving fusing vesicle shrinking. Not only F-actin, but also the F-actin assembly pathway, including ATP hydrolysis, N-WASH, and formin, are involved in mediating these roles of exo- and endocytosis. Neurological disorders, including spinocerebellar ataxia 13 caused by Kv3.3 channel mutation, may involve impairment of F-actin and its assembly pathway, leading in turn to impairment of exo- and endocytosis at synapses that may contribute to neurological disorders.
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Affiliation(s)
- Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States
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6
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Schmied C, Soykan T, Bolz S, Haucke V, Lehmann M. SynActJ: Easy-to-Use Automated Analysis of Synaptic Activity. FRONTIERS IN COMPUTER SCIENCE 2021. [DOI: 10.3389/fcomp.2021.777837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neuronal synapses are highly dynamic communication hubs that mediate chemical neurotransmission via the exocytic fusion and subsequent endocytic recycling of neurotransmitter-containing synaptic vesicles (SVs). Functional imaging tools allow for the direct visualization of synaptic activity by detecting action potentials, pre- or postsynaptic calcium influx, SV exo- and endocytosis, and glutamate release. Fluorescent organic dyes or synapse-targeted genetic molecular reporters, such as calcium, voltage or neurotransmitter sensors and synapto-pHluorins reveal synaptic activity by undergoing rapid changes in their fluorescence intensity upon neuronal activity on timescales of milliseconds to seconds, which typically are recorded by fast and sensitive widefield live cell microscopy. The analysis of the resulting time-lapse movies in the past has been performed by either manually picking individual structures, custom scripts that have not been made widely available to the scientific community, or advanced software toolboxes that are complicated to use. For the precise, unbiased and reproducible measurement of synaptic activity, it is key that the research community has access to bio-image analysis tools that are easy-to-apply and allow the automated detection of fluorescent intensity changes in active synapses. Here we present SynActJ (Synaptic Activity in ImageJ), an easy-to-use fully open-source workflow that enables automated image and data analysis of synaptic activity. The workflow consists of a Fiji plugin performing the automated image analysis of active synapses in time-lapse movies via an interactive seeded watershed segmentation that can be easily adjusted and applied to a dataset in batch mode. The extracted intensity traces of each synaptic bouton are automatically processed, analyzed, and plotted using an R Shiny workflow. We validate the workflow on time-lapse images of stimulated synapses expressing the SV exo-/endocytosis reporter Synaptophysin-pHluorin or a synapse-targeted calcium sensor, Synaptophysin-RGECO. We compare the automatic workflow to manual analysis and compute calcium-influx and SV exo-/endocytosis kinetics and other parameters for synaptic vesicle recycling under different conditions. We predict SynActJ to become an important tool for the analysis of synaptic activity and synapse properties.
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7
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Otterpohl KL, Busselman BW, Ratnayake I, Hart RG, Hart KR, Evans CM, Phillips CL, Beach JR, Ahrenkiel P, Molitoris BA, Surendran K, Chandrasekar I. Conditional Myh9 and Myh10 inactivation in adult mouse renal epithelium results in progressive kidney disease. JCI Insight 2020; 5:138530. [PMID: 33001861 PMCID: PMC7710296 DOI: 10.1172/jci.insight.138530] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 09/23/2020] [Indexed: 01/07/2023] Open
Abstract
Actin-associated nonmuscle myosin II (NM2) motor proteins play critical roles in a myriad of cellular functions, including endocytosis and organelle transport pathways. Cell type–specific expression and unique subcellular localization of the NM2 proteins, encoded by the Myh9 and Myh10 genes, in the mouse kidney tubules led us to hypothesize that these proteins have specialized functional roles within the renal epithelium. Inducible conditional knockout (cKO) of Myh9 and Myh10 in the renal tubules of adult mice resulted in progressive kidney disease. Prior to overt renal tubular injury, we observed intracellular accumulation of the glycosylphosphatidylinositol-anchored protein uromodulin (UMOD) and gradual loss of Na+ K+ 2Cl– cotransporter from the apical membrane of the thick ascending limb epithelia. The UMOD accumulation coincided with expansion of endoplasmic reticulum (ER) tubules and activation of ER stress and unfolded protein response pathways in Myh9&10-cKO kidneys. We conclude that NM2 proteins are required for localization and transport of UMOD and loss of function results in accumulation of UMOD and ER stress–mediated progressive renal tubulointerstitial disease. These observations establish cell type–specific role(s) for NM2 proteins in regulation of specialized renal epithelial transport pathways and reveal the possibility that human kidney disease associated with MYH9 mutations could be of renal epithelial origin. Adult mouse renal epithelium specific knockout of Myh9 and Myh10 genes result in kidney disease.
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Affiliation(s)
- Karla L Otterpohl
- Enabling Technologies Group, Sanford Research, Sioux Falls, South Dakota, USA
| | - Brook W Busselman
- Enabling Technologies Group, Sanford Research, Sioux Falls, South Dakota, USA.,Basic Biomedical Sciences Graduate Program, University of South Dakota, Vermillion, South Dakota, USA
| | - Ishara Ratnayake
- Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA
| | - Ryan G Hart
- Enabling Technologies Group, Sanford Research, Sioux Falls, South Dakota, USA
| | - Kimberly R Hart
- Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, South Dakota, USA
| | - Claire M Evans
- Histology and Imaging Core, Sanford Research, Sioux Falls, South Dakota, USA
| | - Carrie L Phillips
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Jordan R Beach
- Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
| | - Phil Ahrenkiel
- Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA
| | - Bruce A Molitoris
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kameswaran Surendran
- Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, South Dakota, USA.,Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, South Dakota, USA
| | - Indra Chandrasekar
- Enabling Technologies Group, Sanford Research, Sioux Falls, South Dakota, USA.,Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, South Dakota, USA
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8
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Brawley J, Etter E, Heredia D, Intasiri A, Nennecker K, Smith J, Welcome BM, Brizendine RK, Gould TW, Bell TW, Cremo C. Synthesis and Evaluation of 4-Hydroxycoumarin Imines as Inhibitors of Class II Myosins. J Med Chem 2020; 63:11131-11148. [PMID: 32894018 PMCID: PMC8244571 DOI: 10.1021/acs.jmedchem.0c01062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inhibitors of muscle myosin ATPases are needed to treat conditions that could be improved by promoting muscle relaxation. The lead compound for this study ((3-(N-butylethanimidoyl)ethyl)-4-hydroxy-2H-chromen-2-one; BHC) was previously discovered to inhibit skeletal myosin II. BHC and 34 analogues were synthesized to explore structure-activity relationships. The properties of analogues, including solubility, stability, and toxicity, suggest that the BHC scaffold may be useful for developing therapeutics. Inhibition of actin-activated ATPase activity of fast skeletal and cardiac muscle myosin II, inhibition of skeletal muscle contractility ex vivo, and slowing of in vitro actin-sliding velocity were measured. Several analogues with aromatic side arms showed improved potency (half-maximal inhibitory concentration (IC50) <1 μM) and selectivity (≥12-fold) for skeletal myosin versus cardiac myosin compared to BHC. Several analogues blocked neurotransmission, suggesting that they are selective for nonmuscle myosin II over skeletal myosin. Competition and molecular docking studies suggest that BHC and blebbistatin bind to the same site on myosin.
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Affiliation(s)
- Jhonnathan Brawley
- Department of Chemistry, University of Nevada, Reno, Nevada 89557-0216, United States
| | - Emily Etter
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0318, United States
| | - Dante Heredia
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0352, United States
| | - Amarawan Intasiri
- Department of Chemistry, University of Nevada, Reno, Nevada 89557-0216, United States
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kyle Nennecker
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0318, United States
| | - Joshua Smith
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0318, United States
| | - Brandon M Welcome
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0318, United States
| | - Richard K Brizendine
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0318, United States
| | - Thomas W Gould
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0352, United States
| | - Thomas W Bell
- Department of Chemistry, University of Nevada, Reno, Nevada 89557-0216, United States
| | - Christine Cremo
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada 89557-0318, United States
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9
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Conventional and Non-Conventional Roles of Non-Muscle Myosin II-Actin in Neuronal Development and Degeneration. Cells 2020; 9:cells9091926. [PMID: 32825197 PMCID: PMC7566000 DOI: 10.3390/cells9091926] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 12/13/2022] Open
Abstract
Myosins are motor proteins that use chemical energy to produce mechanical forces driving actin cytoskeletal dynamics. In the brain, the conventional non-muscle myosin II (NMII) regulates actin filament cytoskeletal assembly and contractile forces during structural remodeling of axons and dendrites, contributing to morphology, polarization, and migration of neurons during brain development. NMII isoforms also participate in neurotransmission and synaptic plasticity by driving actin cytoskeletal dynamics during synaptic vesicle release and retrieval, and formation, maturation, and remodeling of dendritic spines. NMIIs are expressed differentially in cerebral non-neuronal cells, such as microglia, astrocytes, and endothelial cells, wherein they play key functions in inflammation, myelination, and repair. Besides major efforts to understand the physiological functions and regulatory mechanisms of NMIIs in the nervous system, their contributions to brain pathologies are still largely unclear. Nonetheless, genetic mutations or deregulation of NMII and its regulatory effectors are linked to autism, schizophrenia, intellectual disability, and neurodegeneration, indicating non-conventional roles of NMIIs in cellular mechanisms underlying neurodevelopmental and neurodegenerative disorders. Here, we summarize the emerging biological roles of NMIIs in the brain, and discuss how actomyosin signaling contributes to dysfunction of neurons and glial cells in the context of neurological disorders. This knowledge is relevant for a deep understanding of NMIIs on the pathogenesis and therapeutics of neuropsychiatric and neurodegenerative diseases.
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10
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Trivedi DV, Nag S, Spudich A, Ruppel KM, Spudich JA. The Myosin Family of Mechanoenzymes: From Mechanisms to Therapeutic Approaches. Annu Rev Biochem 2020; 89:667-693. [PMID: 32169021 DOI: 10.1146/annurev-biochem-011520-105234] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Myosins are among the most fascinating enzymes in biology. As extremely allosteric chemomechanical molecular machines, myosins are involved in myriad pivotal cellular functions and are frequently sites of mutations leading to disease phenotypes. Human β-cardiac myosin has proved to be an excellent target for small-molecule therapeutics for heart muscle diseases, and, as we describe here, other myosin family members are likely to be potentially unique targets for treating other diseases as well. The first part of this review focuses on how myosins convert the chemical energy of ATP hydrolysis into mechanical movement, followed by a description of existing therapeutic approaches to target human β-cardiac myosin. The next section focuses on the possibility of targeting nonmuscle members of the human myosin family for several diseases. We end the review by describing the roles of myosin in parasites and the therapeutic potential of targeting them to block parasitic invasion of their hosts.
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Affiliation(s)
- Darshan V Trivedi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA; , , .,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Suman Nag
- MyoKardia Inc., Brisbane, California 94005, USA;
| | - Annamma Spudich
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560-097, India;
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA; , , .,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA.,Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305, USA
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA; , , .,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA
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11
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Otterpohl K, Busselman B, Hart R, Shan K, Lin B, Surendran K, Chandrasekar I. The apical membrane localization and trafficking of uromodulin (UMOD) is critically dependent on nonmuscle myosin II isoforms Myh9 and Myh10 in mouse thick ascending limb epithelial cells. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.862.23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Ryan Hart
- Enabling Technologies GroupSanford ResearchSioux FallsSD
| | - Kevin Shan
- Enabling Technologies GroupSanford ResearchSioux FallsSD
| | - Brendon Lin
- Enabling Technologies GroupSanford ResearchSioux FallsSD
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12
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Maschi D, Gramlich MW, Klyachko VA. Myosin V functions as a vesicle tether at the plasma membrane to control neurotransmitter release in central synapses. eLife 2018; 7:e39440. [PMID: 30320552 PMCID: PMC6209431 DOI: 10.7554/elife.39440] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 10/11/2018] [Indexed: 12/21/2022] Open
Abstract
Synaptic vesicle fusion occurs at specialized release sites at the active zone. How refilling of release sites with new vesicles is regulated in central synapses remains poorly understood. Using nanoscale-resolution detection of individual release events in rat hippocampal synapses we found that inhibition of myosin V, the predominant vesicle-associated motor, strongly reduced refilling of the release sites during repetitive stimulation. Single-vesicle tracking revealed that recycling vesicles continuously shuttle between a plasma membrane pool and an inner pool. Vesicle retention at the membrane pool was regulated by neural activity in a myosin V dependent manner. Ultrastructural measurements of vesicle occupancy at the plasma membrane together with analyses of single-vesicle trajectories during vesicle shuttling between the pools suggest that myosin V acts as a vesicle tether at the plasma membrane, rather than a motor transporting vesicles to the release sites, or directly regulating vesicle exocytosis.
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Affiliation(s)
- Dario Maschi
- Department of Cell Biology and PhysiologyWashington UniversityMissouriUnited States
- Department of Biomedical EngineeringWashington UniversityMissouriUnited States
| | - Michael W Gramlich
- Department of Cell Biology and PhysiologyWashington UniversityMissouriUnited States
- Department of Biomedical EngineeringWashington UniversityMissouriUnited States
| | - Vitaly A Klyachko
- Department of Cell Biology and PhysiologyWashington UniversityMissouriUnited States
- Department of Biomedical EngineeringWashington UniversityMissouriUnited States
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13
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Blebbistatin, a Myosin II Inhibitor, Exerts Antidepressant-Like Activity and Suppresses Detrusor Overactivity in an Animal Model of Depression Coexisting with Overactive Bladder. Neurotox Res 2018; 35:196-207. [PMID: 30155683 PMCID: PMC6313360 DOI: 10.1007/s12640-018-9948-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 12/17/2022]
Abstract
Overactive bladder (OAB) coexists with depression in women. Here, we assessed the effects of a 1-week treatment with blebbistatin, a myosin II inhibitor, on changes in behavior and detrusor overactivity (DO) symptoms induced by a 6-week administration of 13-cis-retinoic acid (13-cis-RA), with the aid of the forced swim test (FST), spontaneous locomotor activity test, and in vivo cystometric investigations in female Wistar rats. 13-cis-RA-induced depressive-like behavior and DO symptoms were associated with increased corticotropin-releasing factor (CRF) level in the plasma, prefrontal cortex (PFC), hippocampus (Hp), Barrington’s nucleus (BN), and urinary bladder. Moreover, 13-cis-RA decreased brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in plasma, PFC, Hp, and BN, while it increased BDNF and NGF levels in urinary bladder. Blebbistatin exerted antidepressant-like effect and attenuated changes in the cystometric parameters as well as the central and peripheral levels of CRF, BDNF, and NGF that were induced by 13-cis-RA, while it did not affect urine production, mean, systolic or diastolic blood pressure, or heart rate. The results point to blebbistatin as a potential treatment option for OAB coexisting with depression.
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14
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Otterpohl KL, Hart RG, Evans C, Surendran K, Chandrasekar I. Nonmuscle myosin 2 proteins encoded by Myh9, Myh10, and Myh14 are uniquely distributed in the tubular segments of murine kidney. Physiol Rep 2018; 5. [PMID: 29208685 PMCID: PMC5727274 DOI: 10.14814/phy2.13513] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 11/24/2022] Open
Abstract
The diverse epithelial cell types of the kidneys are segregated into nephron segments and the collecting ducts in order to endow each tubular segment with unique functions. The rich diversity of the epithelial cell types is highlighted by the unique membrane channels and receptors expressed within each nephron segment. Our previous work identified a critical role for Myh9 and Myh10 in mammalian endocytosis. Here, we examined the expression patterns of Nonmuscle myosin 2 (NM2) heavy chains encoded by Myh9, Myh10, and Myh14 in mouse kidneys as these genes may confer unique nephron segment‐specific membrane transport properties. Interestingly, we found that each segment of the renal tubules predominately expressed only two of the three NM2 isoforms, with isoform‐specific subcellular localization, and different levels of expression within a nephron segment. Additionally, we identify Myh14 to be restricted to the intercalated cells and Myh10 to be restricted to the principal cells within the collecting ducts and connecting segments. We speculate that the distinct expression pattern of the NM2 proteins likely reflects the diversity of the intracellular trafficking machinery present within the different renal tubular epithelial segments.
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Affiliation(s)
- Karla L Otterpohl
- Enabling Technologies Group - Sanford Research, Sioux Falls, South Dakota, USA
| | - Ryan G Hart
- Enabling Technologies Group - Sanford Research, Sioux Falls, South Dakota, USA
| | - Claire Evans
- Molecular Pathology Core, Sanford Research, Sioux Falls, South Dakota, USA
| | - Kameswaran Surendran
- Pediatrics and Rare Diseases Group - Sanford Research, Sioux Falls, South Dakota, USA.,Department of Pediatrics, USD Sanford School of Medicine, Sioux Falls, South Dakota, USA
| | - Indra Chandrasekar
- Enabling Technologies Group - Sanford Research, Sioux Falls, South Dakota, USA.,Department of Pediatrics, USD Sanford School of Medicine, Sioux Falls, South Dakota, USA
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15
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Activity-Dependence of Synaptic Vesicle Dynamics. J Neurosci 2017; 37:10597-10610. [PMID: 28954868 DOI: 10.1523/jneurosci.0383-17.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 08/08/2017] [Accepted: 08/15/2017] [Indexed: 11/21/2022] Open
Abstract
The proper function of synapses relies on efficient recycling of synaptic vesicles. The small size of synaptic boutons has hampered efforts to define the dynamical states of vesicles during recycling. Moreover, whether vesicle motion during recycling is regulated by neural activity remains largely unknown. We combined nanoscale-resolution tracking of individual synaptic vesicles in cultured hippocampal neurons from rats of both sexes with advanced motion analyses to demonstrate that the majority of recently endocytosed vesicles undergo sequences of transient dynamical states including epochs of directed, diffusional, and stalled motion. We observed that vesicle motion is modulated in an activity-dependent manner, with dynamical changes apparent in ∼20% of observed boutons. Within this subpopulation of boutons, 35% of observed vesicles exhibited acceleration and 65% exhibited deceleration, accompanied by corresponding changes in directed motion. Individual vesicles observed in the remaining ∼80% of boutons did not exhibit apparent dynamical changes in response to stimulation. More quantitative transient motion analyses revealed that the overall reduction of vesicle mobility, and specifically of the directed motion component, is the predominant activity-evoked change across the entire bouton population. Activity-dependent modulation of vesicle mobility may represent an important mechanism controlling vesicle availability and neurotransmitter release.SIGNIFICANCE STATEMENT Mechanisms governing synaptic vesicle dynamics during recycling remain poorly understood. Using nanoscale resolution tracking of individual synaptic vesicles in hippocampal synapses and advanced motion analysis tools we demonstrate that synaptic vesicles undergo complex sets of dynamical states that include epochs of directed, diffusive, and stalled motion. Most importantly, our analyses revealed that vesicle motion is modulated in an activity-dependent manner apparent as the reduction in overall vesicle mobility in response to stimulation. These results define the vesicle dynamical states during recycling and reveal their activity-dependent modulation. Our study thus provides fundamental new insights into the principles governing synaptic function.
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16
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Synaptic Vesicle Endocytosis Occurs on Multiple Timescales and Is Mediated by Formin-Dependent Actin Assembly. Neuron 2017; 93:854-866.e4. [DOI: 10.1016/j.neuron.2017.02.011] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 12/12/2016] [Accepted: 01/23/2017] [Indexed: 11/21/2022]
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17
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Optical magnetic detection of single-neuron action potentials using quantum defects in diamond. Proc Natl Acad Sci U S A 2016; 113:14133-14138. [PMID: 27911765 DOI: 10.1073/pnas.1601513113] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Magnetic fields from neuronal action potentials (APs) pass largely unperturbed through biological tissue, allowing magnetic measurements of AP dynamics to be performed extracellularly or even outside intact organisms. To date, however, magnetic techniques for sensing neuronal activity have either operated at the macroscale with coarse spatial and/or temporal resolution-e.g., magnetic resonance imaging methods and magnetoencephalography-or been restricted to biophysics studies of excised neurons probed with cryogenic or bulky detectors that do not provide single-neuron spatial resolution and are not scalable to functional networks or intact organisms. Here, we show that AP magnetic sensing can be realized with both single-neuron sensitivity and intact organism applicability using optically probed nitrogen-vacancy (NV) quantum defects in diamond, operated under ambient conditions and with the NV diamond sensor in close proximity (∼10 µm) to the biological sample. We demonstrate this method for excised single neurons from marine worm and squid, and then exterior to intact, optically opaque marine worms for extended periods and with no observed adverse effect on the animal. NV diamond magnetometry is noninvasive and label-free and does not cause photodamage. The method provides precise measurement of AP waveforms from individual neurons, as well as magnetic field correlates of the AP conduction velocity, and directly determines the AP propagation direction through the inherent sensitivity of NVs to the associated AP magnetic field vector.
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18
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Brettle M, Patel S, Fath T. Tropomyosins in the healthy and diseased nervous system. Brain Res Bull 2016; 126:311-323. [PMID: 27298153 DOI: 10.1016/j.brainresbull.2016.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/09/2016] [Accepted: 06/10/2016] [Indexed: 12/25/2022]
Abstract
Regulation of the actin cytoskeleton is dependent on a plethora of actin-associated proteins in all eukaryotic cells. The family of tropomyosins plays a key role in controlling the function of several of these actin-associated proteins and their access to actin filaments. In order to understand the regulation of the actin cytoskeleton in highly dynamic subcellular compartments of neurons such as growth cones of developing neurons and the synaptic compartment of mature neurons, it is pivotal to decipher the functional role of tropomyosins in the nervous system. In this review, we will discuss the current understanding and recent findings on the regulation of the actin cytoskeleton by tropomyosins and potential implication that this has for the dysregulation of the actin cytoskeleton in neurological diseases.
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Affiliation(s)
- Merryn Brettle
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, 2052 Sydney, New South Wales, Australia
| | - Shrujna Patel
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, 2052 Sydney, New South Wales, Australia
| | - Thomas Fath
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, 2052 Sydney, New South Wales, Australia.
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19
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Li L, Wu X, Yue HY, Zhu YC, Xu J. Myosin light chain kinase facilitates endocytosis of synaptic vesicles at hippocampal boutons. J Neurochem 2016; 138:60-73. [PMID: 27062289 DOI: 10.1111/jnc.13635] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 03/27/2016] [Accepted: 04/05/2016] [Indexed: 02/07/2023]
Abstract
At nerve terminals, endocytosis efficiently recycles vesicle membrane to maintain synaptic transmission under different levels of neuronal activity. Ca(2+) and its downstream signal pathways are critical for the activity-dependent regulation of endocytosis. An activity- and Ca(2+) -dependent kinase, myosin light chain kinase (MLCK) has been reported to regulate vesicle mobilization, vesicle cycling, and motility in different synapses, but whether it has a general contribution to regulation of endocytosis at nerve terminals remains unknown. We investigated this issue at rat hippocampal boutons by imaging vesicle endocytosis as the real-time retrieval of vesicular synaptophysin tagged with a pH-sensitive green fluorescence protein. We found that endocytosis induced by 200 action potentials (5-40 Hz) was slowed by acute inhibition of MLCK and down-regulation of MLCK with RNA interference, while the total amount of vesicle exocytosis and somatic Ca(2+) channel current did not change with MLCK down-regulation. Acute inhibition of myosin II similarly impaired endocytosis. Furthermore, down-regulation of MLCK prevented depolarization-induced phosphorylation of myosin light chain, an effect shared by blockers of Ca(2+) channels and calmodulin. These results suggest that MLCK facilitates vesicle endocytosis through activity-dependent phosphorylation of myosin downstream of Ca(2+) /calmodulin, probably as a widely existing mechanism among synapses. Our study suggests that MLCK is an important activity-dependent regulator of vesicle recycling in hippocampal neurons, which are critical for learning and memory. The kinetics of vesicle membrane endocytosis at nerve terminals has long been known to depend on activity and Ca(2+) . This study provides evidence suggesting that myosin light chain kinase increases endocytosis efficiency at hippocampal neurons by mediating Ca(2+) /calmodulin-dependent phosphorylation of myosin. The authors propose that this signal cascade may serve as a common pathway contributing to the activity-dependent regulation of vesicle endocytosis at synapses.
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Affiliation(s)
- Lin Li
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta, Georgia, USA
| | - Xiaomei Wu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta, Georgia, USA.,Department of Neurochemistry, Institute of Nautical Medicine, Nantong University, Nantong, Jiangsu, China
| | - Hai-Yuan Yue
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta, Georgia, USA
| | - Yong-Chuan Zhu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta, Georgia, USA
| | - Jianhua Xu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta, Georgia, USA.,Department of Neurology, Medical College of Georgia, Augusta, Georgia, USA
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20
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Baydyuk M, Xu J, Wu LG. The calyx of Held in the auditory system: Structure, function, and development. Hear Res 2016; 338:22-31. [PMID: 27018297 DOI: 10.1016/j.heares.2016.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 03/10/2016] [Accepted: 03/17/2016] [Indexed: 12/19/2022]
Abstract
The calyx of Held synapse plays an important role in the auditory system, relaying information about sound localization via fast and precise synaptic transmission, which is achieved by its specialized structure and giant size. During development, the calyx of Held undergoes anatomical, morphological, and physiological changes necessary for performing its functions. The large dimensions of the calyx of Held nerve terminal are well suited for direct electrophysiological recording of many presynaptic events that are difficult, if not impossible to record at small conventional synapses. This unique accessibility has been used to investigate presynaptic ion channels, transmitter release, and short-term plasticity, providing invaluable information about basic presynaptic mechanisms of transmission at a central synapse. Here, we review anatomical and physiological specializations of the calyx of Held, summarize recent studies that provide new mechanisms important for calyx development and reliable synaptic transmission, and examine fundamental presynaptic mechanisms learned from studies using calyx as a model nerve terminal. This article is part of a Special Issue entitled <Annual Reviews 2016>.
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Affiliation(s)
- Maryna Baydyuk
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg 35, Bethesda, MD 20892, USA.
| | - Jianhua Xu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA; Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg 35, Bethesda, MD 20892, USA
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21
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Crawford DC, Kavalali ET. Molecular underpinnings of synaptic vesicle pool heterogeneity. Traffic 2015; 16:338-64. [PMID: 25620674 DOI: 10.1111/tra.12262] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/06/2015] [Indexed: 12/31/2022]
Abstract
Neuronal communication relies on chemical synaptic transmission for information transfer and processing. Chemical neurotransmission is initiated by synaptic vesicle fusion with the presynaptic active zone resulting in release of neurotransmitters. Classical models have assumed that all synaptic vesicles within a synapse have the same potential to fuse under different functional contexts. In this model, functional differences among synaptic vesicle populations are ascribed to their spatial distribution in the synapse with respect to the active zone. Emerging evidence suggests, however, that synaptic vesicles are not a homogenous population of organelles, and they possess intrinsic molecular differences and differential interaction partners. Recent studies have reported a diverse array of synaptic molecules that selectively regulate synaptic vesicles' ability to fuse synchronously and asynchronously in response to action potentials or spontaneously irrespective of action potentials. Here we discuss these molecular mediators of vesicle pool heterogeneity that are found on the synaptic vesicle membrane, on the presynaptic plasma membrane, or within the cytosol and consider some of the functional consequences of this diversity. This emerging molecular framework presents novel avenues to probe synaptic function and uncover how synaptic vesicle pools impact neuronal signaling.
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Affiliation(s)
- Devon C Crawford
- Department of Neuroscience, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9111, USA
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22
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Newell-Litwa KA, Horwitz R, Lamers ML. Non-muscle myosin II in disease: mechanisms and therapeutic opportunities. Dis Model Mech 2015; 8:1495-515. [PMID: 26542704 PMCID: PMC4728321 DOI: 10.1242/dmm.022103] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The actin motor protein non-muscle myosin II (NMII) acts as a master regulator of cell morphology, with a role in several essential cellular processes, including cell migration and post-synaptic dendritic spine plasticity in neurons. NMII also generates forces that alter biochemical signaling, by driving changes in interactions between actin-associated proteins that can ultimately regulate gene transcription. In addition to its roles in normal cellular physiology, NMII has recently emerged as a critical regulator of diverse, genetically complex diseases, including neuronal disorders, cancers and vascular disease. In the context of these disorders, NMII regulatory pathways can be directly mutated or indirectly altered by disease-causing mutations. NMII regulatory pathway genes are also increasingly found in disease-associated copy-number variants, particularly in neuronal disorders such as autism and schizophrenia. Furthermore, manipulation of NMII-mediated contractility regulates stem cell pluripotency and differentiation, thus highlighting the key role of NMII-based pharmaceuticals in the clinical success of stem cell therapies. In this Review, we discuss the emerging role of NMII activity and its regulation by kinases and microRNAs in the pathogenesis and prognosis of a diverse range of diseases, including neuronal disorders, cancer and vascular disease. We also address promising clinical applications and limitations of NMII-based inhibitors in the treatment of these diseases and the development of stem-cell-based therapies.
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Affiliation(s)
- Karen A Newell-Litwa
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Rick Horwitz
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Marcelo L Lamers
- Department of Morphological Sciences, Institute of Basic Health Science, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 90610-010, Brazil
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23
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Chen B, Ma XL, Geng Z, Huang SH, Zhai LK, Guo YY, Chen ZY. Up-regulation of c-Jun NH2-terminal kinase-interacting protein 3 (JIP3) contributes to BDNF-enhanced neurotransmitter release. J Neurochem 2015; 135:453-65. [PMID: 26303065 DOI: 10.1111/jnc.13226] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 06/29/2015] [Accepted: 06/30/2015] [Indexed: 12/22/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has been implicated in the potent modulation of synaptic plasticity at both pre-synaptic and post-synaptic sites. However, the molecular mechanism underlying BDNF-mediated pre-synaptic modulation remains incompletely understood. Here, we report that BDNF treatment for over 4 h could significantly enhance the expression of c-Jun NH2-terminal kinase-interacting protein 3 (JIP3) in cultured hippocampal neurons. This enhancement could be blocked by the Trk inhibitor K252a or by a cAMP response element-binding protein (CREB) inhibitor. In addition, chromatin immunoprecipitation (ChIP) assays revealed that CREB could bind with the JIP3 promoter region and the BDNF treatment could increase this binding. Using dual-luciferase assays we further characterized the cAMP response element (CRE) site in the JIP3 promoter. Finally, we found that BDNF-increased JIP3 expression contributes to the BDNF-induced modulation of neurotransmitter release. Together, our studies reveal that in hippocampal neurons BDNF up-regulates JIP3 expression via CREB activation, which contributes to the enhancement of neurotransmitter release; thus, we have identified a novel mechanism that BDNF modulates pre-synaptic transmission.
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Affiliation(s)
- Bing Chen
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China.,Department of Pathology Tissue Bank, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Xin-Liang Ma
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Zhao Geng
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Shu-Hong Huang
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Lu-Kai Zhai
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Yun-Yun Guo
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Zhe-Yu Chen
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
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24
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Presynaptic NCAM is required for motor neurons to functionally expand their peripheral field of innervation in partially denervated muscles. J Neurosci 2014; 34:10497-510. [PMID: 25100585 DOI: 10.1523/jneurosci.0697-14.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The function of neural cell adhesion molecule (NCAM) expression in motor neurons during axonal sprouting and compensatory reinnervation was explored by partially denervating soleus muscles in mice lacking presynaptic NCAM (Hb9(cre)NCAM(flx)). In agreement with previous studies, the contractile force of muscles in wild-type (NCAM(+/+)) mice recovered completely 2 weeks after 75% of the motor innervation was removed because motor unit size increased by 2.5 times. In contrast, similarly denervated muscles in Hb9(cre)NCAM(flx) mice failed to recover the force lost due to the partial denervation because motor unit size did not change. Anatomical analysis indicated that 50% of soleus end plates were completely denervated 1-4 weeks post-partial denervation in Hb9(cre)NCAM(flx) mice, while another 25% were partially reinnervated. Synaptic vesicles (SVs) remained at extrasynaptic regions in Hb9(cre)NCAM(flx) mice rather than being distributed, as occurs normally, to newly reinnervated neuromuscular junctions (NMJs). Electrophysiological analysis revealed two populations of NMJs in partially denervated Hb9(cre)NCAM(flx) soleus muscles, one with high (mature) quantal content, and another with low (immature) quantal content. Extrasynaptic SVs in Hb9(cre)NCAM(flx) sprouts were associated with L-type voltage-dependent calcium channel (L-VDCC) immunoreactivity and maintained an immature, L-VDCC-dependent recycling phenotype. Moreover, acute nifedipine treatment potentiated neurotransmission at newly sprouted NMJs, while chronic intraperitoneal treatment with nifedipine during a period of synaptic consolidation enhanced functional motor unit expansion in the absence of presynaptic NCAM. We propose that presynaptic NCAM bridges a critical link between the SV cycle and the functional expansion of synaptic territory through the regulation of L-VDCCs.
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25
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Flores JA, Balseiro-Gomez S, Cabeza JM, Acosta J, Ramirez-Ponce P, Ales E. A new role for myosin II in vesicle fission. PLoS One 2014; 9:e100757. [PMID: 24959909 PMCID: PMC4069105 DOI: 10.1371/journal.pone.0100757] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/28/2014] [Indexed: 11/19/2022] Open
Abstract
An endocytic vesicle is formed from a flat plasma membrane patch by a sequential process of invagination, bud formation and fission. The scission step requires the formation of a tubular membrane neck (the fission pore) that connects the endocytic vesicle with the plasma membrane. Progress in vesicle fission can be measured by the formation and closure of the fission pore. Live-cell imaging and sensitive biophysical measurements have provided various glimpses into the structure and behaviour of the fission pore. In the present study, the role of non-muscle myosin II (NM-2) in vesicle fission was tested by analyzing the kinetics of the fission pore with perforated-patch clamp capacitance measurements to detect single vesicle endocytosis with millisecond time resolution in peritoneal mast cells. Blebbistatin, a specific inhibitor of NM-2, dramatically increased the duration of the fission pore and also prevented closure during large endocytic events. Using the fluorescent markers FM1-43 and pHrodo Green dextran, we found that NM-2 inhibition greatly arrested vesicle fission in a late phase of the scission event when the pore reached a final diameter of ∼ 5 nm. Our results indicate that loss of the ATPase activity of myosin II drastically reduces the efficiency of membrane scission by making vesicle closure incomplete and suggest that NM-2 might be especially relevant in vesicle fission during compound endocytosis.
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Affiliation(s)
- Juan A. Flores
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Santiago Balseiro-Gomez
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Jose M. Cabeza
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Jorge Acosta
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Pilar Ramirez-Ponce
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Eva Ales
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
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26
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Favretto ME, Wallbrecher R, Schmidt S, van de Putte R, Brock R. Glycosaminoglycans in the cellular uptake of drug delivery vectors – Bystanders or active players? J Control Release 2014; 180:81-90. [DOI: 10.1016/j.jconrel.2014.02.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/07/2014] [Accepted: 02/09/2014] [Indexed: 12/30/2022]
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27
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Chandrasekar I, Goeckeler ZM, Turney SG, Wang P, Wysolmerski RB, Adelstein RS, Bridgman PC. Nonmuscle myosin II is a critical regulator of clathrin-mediated endocytosis. Traffic 2014; 15:418-32. [PMID: 24443954 PMCID: PMC3975594 DOI: 10.1111/tra.12152] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 01/10/2014] [Accepted: 01/20/2014] [Indexed: 02/03/2023]
Abstract
Variable requirements for actin during clathrin-mediated endocytosis (CME) may be related to regional or cellular differences in membrane tension. To compensate, local regulation of force generation may be needed to facilitate membrane curving and vesicle budding. Force generation is assumed to occur primarily through actin polymerization. Here we examine the role of myosin II using loss of function experiments. Our results indicate that myosin II acts on cortical actin scaffolds primarily in the plane of the plasma membrane (bottom arrow) to generate changes that are critical for enhancing CME progression.
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Affiliation(s)
- Indra Chandrasekar
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Zoe M. Goeckeler
- Department of Neurobiology and Anatomy, Mary Babb Randolph Cancer Center, West Virginia University School of Medicine, Morgantown, WV 26506
| | - Stephen G. Turney
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Peter Wang
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Robert B. Wysolmerski
- Department of Neurobiology and Anatomy, Mary Babb Randolph Cancer Center, West Virginia University School of Medicine, Morgantown, WV 26506
| | | | - Paul C. Bridgman
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
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28
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Abstract
Neuronal activity triggers endocytosis at synaptic terminals to retrieve efficiently the exocytosed vesicle membrane, ensuring the membrane homeostasis of active zones and the continuous supply of releasable vesicles. The kinetics of endocytosis depends on Ca(2+) and calmodulin which, as a versatile signal pathway, can activate a broad spectrum of downstream targets, including myosin light chain kinase (MLCK). MLCK is known to regulate vesicle trafficking and synaptic transmission, but whether this kinase regulates vesicle endocytosis at synapses remains elusive. We investigated this issue at the rat calyx of Held synapse, where previous studies using whole-cell membrane capacitance measurement have characterized two common forms of Ca(2+)/calmodulin-dependent endocytosis, i.e., slow clathrin-dependent endocytosis and rapid endocytosis. Acute inhibition of MLCK with pharmacological agents was found to slow down the kinetics of both slow and rapid forms of endocytosis at calyces. Similar impairment of endocytosis occurred when blocking myosin II, a motor protein that can be phosphorylated upon MLCK activation. The inhibition of endocytosis was not accompanied by a change in Ca(2+) channel current. Combined inhibition of MLCK and calmodulin did not induce synergistic inhibition of endocytosis. Together, our results suggest that activation of MLCK accelerates both slow and rapid forms of vesicle endocytosis at nerve terminals, likely by functioning downstream of Ca(2+)/calmodulin.
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