1
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Esposito A, Pepe S, Cerullo MS, Cortese K, Semini HT, Giovedì S, Guerrini R, Benfenati F, Falace A, Fassio A. ATP6V1A is required for synaptic rearrangements and plasticity in murine hippocampal neurons. Acta Physiol (Oxf) 2024; 240:e14186. [PMID: 38837572 DOI: 10.1111/apha.14186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 05/05/2024] [Accepted: 05/23/2024] [Indexed: 06/07/2024]
Abstract
AIM Understanding the physiological role of ATP6V1A, a component of the cytosolic V1 domain of the proton pump vacuolar ATPase, in regulating neuronal development and function. METHODS Modeling loss of function of Atp6v1a in primary murine hippocampal neurons and studying neuronal morphology and function by immunoimaging, electrophysiological recordings and electron microscopy. RESULTS Atp6v1a depletion affects neurite elongation, stabilization, and function of excitatory synapses and prevents synaptic rearrangement upon induction of plasticity. These phenotypes are due to an overall decreased expression of the V1 subunits, that leads to impairment of lysosomal pH-regulation and autophagy progression with accumulation of aberrant lysosomes at neuronal soma and of enlarged vacuoles at synaptic boutons. CONCLUSIONS These data suggest a physiological role of ATP6V1A in the surveillance of synaptic integrity and plasticity and highlight the pathophysiological significance of ATP6V1A loss in the alteration of synaptic function that is associated with neurodevelopmental and neurodegenerative diseases. The data further support the pivotal involvement of lysosomal function and autophagy flux in maintaining proper synaptic connectivity and adaptive neuronal properties.
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Affiliation(s)
| | - Sara Pepe
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
| | - Maria Sabina Cerullo
- Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Genoa, Italy
| | - Katia Cortese
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | | | - Silvia Giovedì
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
| | - Renzo Guerrini
- Children's Hospital A. Meyer IRCCS, Florence, Italy
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, University of Florence, Florence, Italy
| | - Fabio Benfenati
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
- Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Genoa, Italy
| | - Antonio Falace
- Children's Hospital A. Meyer IRCCS, Florence, Italy
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto "Giannina Gaslini", Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
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2
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Coupland CE, Karimi R, Bueler SA, Liang Y, Courbon GM, Di Trani JM, Wong CJ, Saghian R, Youn JY, Wang LY, Rubinstein JL. High-resolution electron cryomicroscopy of V-ATPase in native synaptic vesicles. Science 2024; 385:168-174. [PMID: 38900912 DOI: 10.1126/science.adp5577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 05/16/2024] [Indexed: 06/22/2024]
Abstract
Intercellular communication in the nervous system occurs through the release of neurotransmitters into the synaptic cleft between neurons. In the presynaptic neuron, the proton pumping vesicular- or vacuolar-type ATPase (V-ATPase) powers neurotransmitter loading into synaptic vesicles (SVs), with the V1 complex dissociating from the membrane region of the enzyme before exocytosis. We isolated SVs from rat brain using SidK, a V-ATPase-binding bacterial effector protein. Single-particle electron cryomicroscopy allowed high-resolution structure determination of V-ATPase within the native SV membrane. In the structure, regularly spaced cholesterol molecules decorate the enzyme's rotor and the abundant SV protein synaptophysin binds the complex stoichiometrically. ATP hydrolysis during vesicle loading results in a loss of the V1 region of V-ATPase from the SV membrane, suggesting that loading is sufficient to induce dissociation of the enzyme.
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Affiliation(s)
- Claire E Coupland
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
| | - Ryan Karimi
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
- Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
| | - Yingke Liang
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
- Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Gautier M Courbon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
- Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Justin M Di Trani
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
| | - Cassandra J Wong
- Lunenfeld-Tanenbaum Research Institute, Toronto, ON M5G 1X5, Canada
| | - Rayan Saghian
- Neuroscience and Mental Health Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
- Department of Physiology, The University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ji-Young Youn
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
- Department of Molecular Genetics, The University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Lu-Yang Wang
- Neuroscience and Mental Health Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
- Department of Physiology, The University of Toronto, Toronto, ON M5S 1A8, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X1, Canada
- Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada
- Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
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3
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Oot RA, Wilkens S. Human V-ATPase function is positively and negatively regulated by TLDc proteins. Structure 2024; 32:989-1000.e6. [PMID: 38593795 PMCID: PMC11246223 DOI: 10.1016/j.str.2024.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/23/2024] [Accepted: 03/13/2024] [Indexed: 04/11/2024]
Abstract
Proteins that contain a highly conserved TLDc domain (Tre2/Bub2/Cdc16 LysM domain catalytic) offer protection against oxidative stress and are widely implicated in neurological health and disease. How this family of proteins exerts their function, however, is poorly understood. We have recently found that the yeast TLDc protein, Oxr1p, inhibits the proton pumping vacuolar ATPase (V-ATPase) by inducing disassembly of the pump. While loss of TLDc protein function in mammals shares disease phenotypes with V-ATPase defects, whether TLDc proteins impact human V-ATPase activity directly is unclear. Here we examine the effects of five human TLDc proteins, TLDC2, NCOA7, OXR1, TBC1D24, and mEAK7 on the activity of the human V-ATPase. We find that while TLDC2, TBC1D24, and the TLDc domains of OXR1 and NCOA7 inhibit V-ATPase by inducing enzyme disassembly, mEAK7 activates the pump. The data thus shed new light both on mammalian TLDc protein function and V-ATPase regulation.
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Affiliation(s)
- Rebecca A Oot
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
| | - Stephan Wilkens
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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4
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Eaton AF, Danielson EC, Capen D, Merkulova M, Brown D. Dmxl1 Is an Essential Mammalian Gene that Is Required for V-ATPase Assembly and Function In Vivo. FUNCTION 2024; 5:zqae025. [PMID: 38984989 PMCID: PMC11237898 DOI: 10.1093/function/zqae025] [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: 04/16/2024] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 07/11/2024] Open
Abstract
The proton pumping V-ATPase drives essential biological processes, such as acidification of intracellular organelles. Critically, the V-ATPase domains, V1 and VO, must assemble to produce a functional holoenzyme. V-ATPase dysfunction results in cancer, neurodegeneration, and diabetes, as well as systemic acidosis caused by reduced activity of proton-secreting kidney intercalated cells (ICs). However, little is known about the molecular regulation of V-ATPase in mammals. We identified a novel interactor of the mammalian V-ATPase, Drosophila melanogaster X chromosomal gene-like 1 (Dmxl1), aka Rabconnectin-3A. The yeast homologue of Dmxl1, Rav1p, is part of a complex that catalyzes the reversible assembly of the domains. We, therefore,hypothesized that Dmxl1 is a mammalian V-ATPase assembly factor. Here, we generated kidney IC-specific Dmxl1 knockout (KO) mice, which had high urine pH, like B1 V-ATPase KO mice, suggesting impaired V-ATPase function. Western blotting showed decreased B1 expression and B1 (V1) and a4 (VO) subunits were more intracellular and less colocalized in Dmxl1 KO ICs. In parallel, subcellular fractionation revealed less V1 associated B1 in the membrane fraction of KO cells relative to the cytosol. Furthermore, a proximity ligation assay performed using probes against B1 and a4 V-ATPase subunits also revealed decreased association. We propose that loss of Dmxl1 reduces V-ATPase holoenzyme assembly, thereby inhibiting proton pumping function. Dmxl1 may recruit the V1 domain to the membrane and facilitate assembly with the VO domain and in its absence V1 may be targeted for degradation. We conclude that Dmxl1 is a bona fide mammalian V-ATPase assembly factor.
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Affiliation(s)
- Amity F Eaton
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Elizabeth C Danielson
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Diane Capen
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Maria Merkulova
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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5
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Wang C, Jiang W, Leitz J, Yang K, Esquivies L, Wang X, Shen X, Held RG, Adams DJ, Basta T, Hampton L, Jian R, Jiang L, Stowell MHB, Baumeister W, Guo Q, Brunger AT. Structure and topography of the synaptic V-ATPase-synaptophysin complex. Nature 2024; 631:899-904. [PMID: 38838737 PMCID: PMC11269182 DOI: 10.1038/s41586-024-07610-x] [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: 04/09/2024] [Accepted: 05/24/2024] [Indexed: 06/07/2024]
Abstract
Synaptic vesicles are organelles with a precisely defined protein and lipid composition1,2, yet the molecular mechanisms for the biogenesis of synaptic vesicles are mainly unknown. Here we discovered a well-defined interface between the synaptic vesicle V-ATPase and synaptophysin by in situ cryo-electron tomography and single-particle cryo-electron microscopy of functional synaptic vesicles isolated from mouse brains3. The synaptic vesicle V-ATPase is an ATP-dependent proton pump that establishes the proton gradient across the synaptic vesicle, which in turn drives the uptake of neurotransmitters4,5. Synaptophysin6 and its paralogues synaptoporin7 and synaptogyrin8 belong to a family of abundant synaptic vesicle proteins whose function is still unclear. We performed structural and functional studies of synaptophysin-knockout mice, confirming the identity of synaptophysin as an interaction partner with the V-ATPase. Although there is little change in the conformation of the V-ATPase upon interaction with synaptophysin, the presence of synaptophysin in synaptic vesicles profoundly affects the copy number of V-ATPases. This effect on the topography of synaptic vesicles suggests that synaptophysin assists in their biogenesis. In support of this model, we observed that synaptophysin-knockout mice exhibit severe seizure susceptibility, suggesting an imbalance of neurotransmitter release as a physiological consequence of the absence of synaptophysin.
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Affiliation(s)
- Chuchu Wang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- Department of Structural Biology, Stanford University, Stanford, CA, USA
- Department of Photon Science, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Wenhong Jiang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Jeremy Leitz
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- Department of Structural Biology, Stanford University, Stanford, CA, USA
- Department of Photon Science, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Kailu Yang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- Department of Structural Biology, Stanford University, Stanford, CA, USA
- Department of Photon Science, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Luis Esquivies
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- Department of Structural Biology, Stanford University, Stanford, CA, USA
- Department of Photon Science, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Xing Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Xiaotao Shen
- Department of Genetics, Stanford University, Stanford, CA, USA
- Stanford Center for Genomics and Personalized Medicine, Stanford University, Stanford, CA, USA
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Richard G Held
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- Department of Structural Biology, Stanford University, Stanford, CA, USA
- Department of Photon Science, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Daniel J Adams
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Tamara Basta
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Lucas Hampton
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Ruiqi Jian
- Department of Genetics, Stanford University, Stanford, CA, USA
- Stanford Center for Genomics and Personalized Medicine, Stanford University, Stanford, CA, USA
| | - Lihua Jiang
- Department of Genetics, Stanford University, Stanford, CA, USA
- Stanford Center for Genomics and Personalized Medicine, Stanford University, Stanford, CA, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Wolfgang Baumeister
- Department of Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Qiang Guo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.
- Department of Structural Biology, Stanford University, Stanford, CA, USA.
- Department of Photon Science, Stanford University, Stanford, CA, USA.
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA.
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6
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Fang Y, Feng H, Zhang B, Zhang S, Zhou Y, Hao P, Zhou Z, Zhou S, Li N, Hui Y, Ma L, Xiong J, Wu J, Liu L, Zhang X. Cytosolic pH is a direct nexus in linking environmental cues with insulin processing and secretion in pancreatic β cells. Cell Metab 2024; 36:1237-1251.e4. [PMID: 38513648 DOI: 10.1016/j.cmet.2024.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 09/01/2023] [Accepted: 02/22/2024] [Indexed: 03/23/2024]
Abstract
Pancreatic β cells actively respond to glucose fluctuations through regulating insulin processing and secretion. However, how this process is elaborately tuned in circumstance of variable microenvironments as well as β cell-intrinsic states and whether its dysfunction links to metabolic diseases remain largely elusive. Here, we show that the cytosolic pH (pHc) in β cells is increased upon glucose challenge, which can be sensed by Smad5 via its nucleocytoplasmic shuttling. Lesion of Smad5 in β cells results in hyperglycemia and glucose intolerance due to insulin processing and secretion deficiency. The role of Smad5 in regulating insulin processing and secretion attributes to its non-canonical function by regulating V-ATPase activity for granule acidification. Genetic mutation of Smad5 or administration of alkaline water to mirror cytosolic alkalization ameliorated glucose intolerance in high-fat diet (HFD)-treated mice. Collectively, our findings suggest that pHc is a direct nexus in linking environmental cues with insulin processing and secretion in β cells.
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Affiliation(s)
- Yujiang Fang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.
| | - Hexi Feng
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Bowen Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Shuwei Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Yanjie Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Pengcheng Hao
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Zhongshu Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Shanshan Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Nan Li
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Yi Hui
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Lin Ma
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Jie Xiong
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Jinjin Wu
- Shanghai Children's Medical Center, Shanghai Jiaotong University, Shanghai, China
| | - Ling Liu
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.
| | - Xiaoqing Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China; Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China; Clinical Center for Brain and Spinal Cord Research, Tongji University, Shanghai, China.
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7
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Khan MM, Wilkens S. Molecular mechanism of Oxr1p mediated disassembly of yeast V-ATPase. EMBO Rep 2024; 25:2323-2347. [PMID: 38565737 PMCID: PMC11094088 DOI: 10.1038/s44319-024-00126-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 03/07/2024] [Accepted: 03/09/2024] [Indexed: 04/04/2024] Open
Abstract
The eukaryotic vacuolar H+-ATPase (V-ATPase) is regulated by reversible disassembly into autoinhibited V1-ATPase and Vo proton channel subcomplexes. We recently reported that the TLDc protein Oxr1p induces V-ATPase disassembly in vitro. Whether and how Oxr1p is involved in enzyme disassembly in vivo, however, is not known. Here, using yeast genetics and fluorescence microscopy, we show that Oxr1p is essential for efficient V-ATPase disassembly in the cell. Supporting biochemical and biophysical in vitro experiments show that whereas Oxr1p-driven holoenzyme disassembly can occur in the absence of nucleotides, the presence of ATP greatly accelerates the process. ATP hydrolysis is needed, however, for subsequent release of Oxr1p so that the free V1 can adopt the autoinhibited conformation. Overall, our study unravels the molecular mechanism of Oxr1p-induced disassembly that occurs in vivo as part of the canonical V-ATPase regulation by reversible disassembly.
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Affiliation(s)
- Md Murad Khan
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
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8
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Sava I, Davis LJ, Gray SR, Bright NA, Luzio JP. Reversible assembly and disassembly of V-ATPase during the lysosome regeneration cycle. Mol Biol Cell 2024; 35:ar63. [PMID: 38446621 PMCID: PMC11151095 DOI: 10.1091/mbc.e23-08-0322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 02/23/2024] [Accepted: 03/01/2024] [Indexed: 03/08/2024] Open
Abstract
Regulation of the luminal pH of late endocytic compartments in continuously fed mammalian cells is poorly understood. Using normal rat kidney fibroblasts, we investigated the reversible assembly/disassembly of the proton pumping V-ATPase when endolysosomes are formed by kissing and fusion of late endosomes with lysosomes and during the subsequent reformation of lysosomes. We took advantage of previous work showing that sucrosomes formed by the uptake of sucrose are swollen endolysosomes from which lysosomes are reformed after uptake of invertase. Using confocal microscopy and subcellular fractionation of NRK cells stably expressing fluorescently tagged proteins, we found net recruitment of the V1 subcomplex during sucrosome formation and loss during lysosome reformation, with a similar time course to RAB7a loss. Addition of invertase did not alter mTORC1 signalling, suggesting that the regulation of reversible V-ATPase assembly/disassembly in continuously fed cells differs from that in cells subject to amino acid depletion/refeeding. Using live cell microscopy, we demonstrated recruitment of a fluorescently tagged V1 subunit during endolysosome formation and a dynamic equilibrium and rapid exchange between the cytosolic and membrane bound pools of this subunit. We conclude that reversible V-ATPase assembly/disassembly plays a key role in regulating endolysosomal/lysosomal pH in continuously fed cells.
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Affiliation(s)
- Ioana Sava
- Cambridge Institute for Medical Research (CIMR) and Department of Clinical Biochemistry, University of Cambridge School of Clinical Medicine, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Luther J. Davis
- Cambridge Institute for Medical Research (CIMR) and Department of Clinical Biochemistry, University of Cambridge School of Clinical Medicine, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Sally R. Gray
- Cambridge Institute for Medical Research (CIMR) and Department of Clinical Biochemistry, University of Cambridge School of Clinical Medicine, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Nicholas A. Bright
- Cambridge Institute for Medical Research (CIMR) and Department of Clinical Biochemistry, University of Cambridge School of Clinical Medicine, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - J. Paul Luzio
- Cambridge Institute for Medical Research (CIMR) and Department of Clinical Biochemistry, University of Cambridge School of Clinical Medicine, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
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9
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Kane PM. A yeast vacuolar pH 'heartbeat' coordinates amino acid metabolism and the cell cycle. Nat Metab 2023; 5:1652-1653. [PMID: 37640942 DOI: 10.1038/s42255-023-00875-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Affiliation(s)
- Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA.
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10
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Kim SH, Cho YS, Kim Y, Park J, Yoo SM, Gwak J, Kim Y, Gwon Y, Kam TI, Jung YK. Endolysosomal impairment by binding of amyloid beta or MAPT/Tau to V-ATPase and rescue via the HYAL-CD44 axis in Alzheimer disease. Autophagy 2023; 19:2318-2337. [PMID: 36843263 PMCID: PMC10351450 DOI: 10.1080/15548627.2023.2181614] [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: 04/14/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/28/2023] Open
Abstract
Impaired activities and abnormally enlarged structures of endolysosomes are frequently observed in Alzheimer disease (AD) brains. However, little is known about whether and how endolysosomal dysregulation is triggered and associated with AD. Here, we show that vacuolar ATPase (V-ATPase) is a hub that mediates proteopathy of oligomeric amyloid beta (Aβ) and hyperphosphorylated MAPT/Tau (p-MAPT/Tau). Endolysosomal integrity was largely destroyed in Aβ-overloaded or p-MAPT/Tau-positive neurons in culture and AD brains, which was a necessary step for triggering neurotoxicity, and treatments with acidic nanoparticles or endocytosis inhibitors rescued the endolysosomal impairment and neurotoxicity. Interestingly, we found that the lumenal ATP6V0C and cytosolic ATP6V1B2 subunits of the V-ATPase complex bound to the internalized Aβ and cytosolic PHF-1-reactive MAPT/Tau, respectively. Their interactions disrupted V-ATPase activity and accompanying endolysosomal activity in vitro and induced neurodegeneration. Using a genome-wide functional screen, we isolated a suppressor, HYAL (hyaluronidase), which reversed the endolysosomal dysfunction and proteopathy and alleviated the memory impairment in 3xTg-AD mice. Further, we found that its metabolite hyaluronic acid (HA) and HA receptor CD44 attenuated neurotoxicity in affected neurons via V-ATPase. We propose that endolysosomal V-ATPase is a bona fide proteotoxic receptor that binds to pathogenic proteins and deteriorates endolysosomal function in AD, leading to neurodegeneration in proteopathy.Abbreviations: AAV, adeno-associated virus; Aβ, amyloid beta; AD, Alzheimer disease; APP, amyloid beta precursor protein; ATP6V0C, ATPase H+ transporting V0 subunit c; ATP6V1A, ATPase H+ transporting V1 subunit A; ATP6V1B2, ATPase H+ transporting V1 subunit B2; CD44.Fc, CD44-mouse immunoglobulin Fc fusion construct; Co-IP, co-immunoprecipitation; CTSD, cathepsin D; HA, hyaluronic acid; HMWHA, high-molecular-weight hyaluronic acid; HYAL, hyaluronidase; i.c.v, intracerebroventricular; LMWHA, low-molecular-weight hyaluronic acid; NPs, nanoparticles; p-MAPT/Tau, hyperphosphorylated microtubule associated protein tau; PI3K, phosphoinositide 3-kinase; V-ATPase, vacuolar-type H+-translocating ATPase; WT, wild-type.
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Affiliation(s)
- Seo-Hyun Kim
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Young-Sin Cho
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Youbin Kim
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, Korea
| | - Jisu Park
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Seung-Min Yoo
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Jimin Gwak
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Youngwon Kim
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Youngdae Gwon
- School of Medicine, Sungkyunkwan University, Suwon, Korea
| | - Tae-in Kam
- Department of Neurology and Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yong-Keun Jung
- School of Biological Sciences, Seoul National University, Seoul, Korea
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, Korea
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11
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Indrawinata K, Argiropoulos P, Sugita S. Structural and functional understanding of disease-associated mutations in V-ATPase subunit a1 and other isoforms. Front Mol Neurosci 2023; 16:1135015. [PMID: 37465367 PMCID: PMC10352029 DOI: 10.3389/fnmol.2023.1135015] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/09/2023] [Indexed: 07/20/2023] Open
Abstract
The vacuolar-type ATPase (V-ATPase) is a multisubunit protein composed of the cytosolic adenosine triphosphate (ATP) hydrolysis catalyzing V1 complex, and the integral membrane complex, Vo, responsible for proton translocation. The largest subunit of the Vo complex, subunit a, enables proton translocation upon ATP hydrolysis, mediated by the cytosolic V1 complex. Four known subunit a isoforms (a1-a4) are expressed in different cellular locations. Subunit a1 (also known as Voa1), the neural isoform, is strongly expressed in neurons and is encoded by the ATP6V0A1 gene. Global knockout of this gene in mice causes embryonic lethality, whereas pyramidal neuron-specific knockout resulted in neuronal cell death with impaired spatial and learning memory. Recently reported, de novo and biallelic mutations of the human ATP6V0A1 impair autophagic and lysosomal activities, contributing to neuronal cell death in developmental and epileptic encephalopathies (DEE) and early onset progressive myoclonus epilepsy (PME). The de novo heterozygous R740Q mutation is the most recurrent variant reported in cases of DEE. Homology studies suggest R740 deprotonates protons from specific glutamic acid residues in subunit c, highlighting its importance to the overall V-ATPase function. In this paper, we discuss the structure and mechanism of the V-ATPase, emphasizing how mutations in subunit a1 can lead to lysosomal and autophagic dysfunction in neurodevelopmental disorders, and how mutations to the non-neural isoforms, a2-a4, can also lead to various genetic diseases. Given the growing discovery of disease-causing variants of V-ATPase subunit a and its function as a pump-based regulator of intracellular organelle pH, this multiprotein complex warrants further investigation.
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Affiliation(s)
- Karen Indrawinata
- Division of Translational and Experimental Neuroscience, Krembil Brain Institute, University Health Network, Toronto, ON, Canada
| | - Peter Argiropoulos
- Division of Translational and Experimental Neuroscience, Krembil Brain Institute, University Health Network, Toronto, ON, Canada
| | - Shuzo Sugita
- Division of Translational and Experimental Neuroscience, Krembil Brain Institute, University Health Network, Toronto, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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12
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Wilkens S, Khan MM, Knight K, Oot R. Tender love and disassembly: How a TLDc domain protein breaks the V-ATPase. Bioessays 2023; 45:e2200251. [PMID: 37183929 PMCID: PMC10392918 DOI: 10.1002/bies.202200251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 04/13/2023] [Accepted: 05/03/2023] [Indexed: 05/16/2023]
Abstract
Vacuolar ATPases (V-ATPases, V1 Vo -ATPases) are rotary motor proton pumps that acidify intracellular compartments, and, when localized to the plasma membrane, the extracellular space. V-ATPase is regulated by a unique process referred to as reversible disassembly, wherein V1 -ATPase disengages from Vo proton channel in response to diverse environmental signals. Whereas the disassembly step of this process is ATP dependent, the (re)assembly step is not, but requires the action of a heterotrimeric chaperone referred to as the RAVE complex. Recently, an alternative pathway of holoenzyme disassembly was discovered that involves binding of Oxidation Resistance 1 (Oxr1p), a poorly characterized protein implicated in oxidative stress response. Unlike conventional reversible disassembly, which depends on enzyme activity, Oxr1p induced dissociation can occur in absence of ATP. Yeast Oxr1p belongs to the family of TLDc domain containing proteins that are conserved from yeast to mammals, and have been implicated in V-ATPase function in a variety of tissues. This brief perspective summarizes what we know about the molecular mechanisms governing both reversible (ATP dependent) and Oxr1p driven (ATP independent) V-ATPase dissociation into autoinhibited V1 and Vo subcomplexes.
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Affiliation(s)
- Stephan Wilkens
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Md. Murad Khan
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Kassidy Knight
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Rebecca Oot
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
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13
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Dittrich A, Ramesh G, Jung M, Schmitz F. Rabconnectin-3α/DMXL2 Is Locally Enriched at the Synaptic Ribbon of Rod Photoreceptor Synapses. Cells 2023; 12:1665. [PMID: 37371135 DOI: 10.3390/cells12121665] [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: 04/28/2023] [Revised: 06/08/2023] [Accepted: 06/17/2023] [Indexed: 06/29/2023] Open
Abstract
Ribbon synapses reliably transmit synaptic signals over a broad signalling range. Rod photoreceptor ribbon synapses are capable of transmitting signals generated by the absorption of single photons. The high precision of ribbon synapses emphasizes the need for particularly efficient signalling mechanisms. Synaptic ribbons are presynaptic specializations of ribbon synapses and are anchored to the active zone. Synaptic ribbons bind many synaptic vesicles that are delivered to the active zone for continuous and faithful signalling. In the present study we demonstrate with independent antibodies at the light- and electron microscopic level that rabconnectin-3α (RC3α)-alternative name Dmx-like 2 (DMXL2)-is localized to the synaptic ribbons of rod photoreceptor synapses in the mouse retina. In the brain, RC3α-containing complexes are known to interact with important components of synaptic vesicles, including Rab3-activating/inactivating enzymes, priming proteins and the vesicular H+-ATPase that acidifies the synaptic vesicle lumen to promote full neurotransmitter loading. The association of RC3α/DMXL2 with rod synaptic ribbons of the mouse retina could enable these structures to deliver only fully signalling-competent synaptic vesicles to the active zone thus contributing to reliable synaptic communication.
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Affiliation(s)
- Alina Dittrich
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Girish Ramesh
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
- Institute of Biophysics, Saarland University, 66421 Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
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14
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Tuli F, Kane PM. The cytosolic N-terminal domain of V-ATPase a-subunits is a regulatory hub targeted by multiple signals. Front Mol Biosci 2023; 10:1168680. [PMID: 37398550 PMCID: PMC10313074 DOI: 10.3389/fmolb.2023.1168680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/05/2023] [Indexed: 07/04/2023] Open
Abstract
Vacuolar H+-ATPases (V-ATPases) acidify several organelles in all eukaryotic cells and export protons across the plasma membrane in a subset of cell types. V-ATPases are multisubunit enzymes consisting of a peripheral subcomplex, V1, that is exposed to the cytosol and an integral membrane subcomplex, Vo, that contains the proton pore. The Vo a-subunit is the largest membrane subunit and consists of two domains. The N-terminal domain of the a-subunit (aNT) interacts with several V1 and Vo subunits and serves to bridge the V1 and Vo subcomplexes, while the C-terminal domain contains eight transmembrane helices, two of which are directly involved in proton transport. Although there can be multiple isoforms of several V-ATPase subunits, the a-subunit is encoded by the largest number of isoforms in most organisms. For example, the human genome encodes four a-subunit isoforms that exhibit a tissue- and organelle-specific distribution. In the yeast S. cerevisiae, the two a-subunit isoforms, Golgi-enriched Stv1 and vacuolar Vph1, are the only V-ATPase subunit isoforms. Current structural information indicates that a-subunit isoforms adopt a similar backbone structure but sequence variations allow for specific interactions during trafficking and in response to cellular signals. V-ATPases are subject to several types of environmental regulation that serve to tune their activity to their cellular location and environmental demands. The position of the aNT domain in the complex makes it an ideal target for modulating V1-Vo interactions and regulating enzyme activity. The yeast a-subunit isoforms have served as a paradigm for dissecting interactions of regulatory inputs with subunit isoforms. Importantly, structures of yeast V-ATPases containing each a-subunit isoform are available. Chimeric a-subunits combining elements of Stv1NT and Vph1NT have provided insights into how regulatory inputs can be integrated to allow V-ATPases to support cell growth under different stress conditions. Although the function and distribution of the four mammalian a-subunit isoforms present additional complexity, it is clear that the aNT domains of these isoforms are also subject to multiple regulatory interactions. Regulatory mechanisms that target mammalian a-subunit isoforms, and specifically the aNT domains, will be described. Altered V-ATPase function is associated with multiple diseases in humans. The possibility of regulating V-ATPase subpopulations via their isoform-specific regulatory interactions are discussed.
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Affiliation(s)
| | - Patricia M. Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
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15
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Wang H, Rubinstein JL. CryoEM of V-ATPases: Assembly, disassembly, and inhibition. Curr Opin Struct Biol 2023; 80:102592. [PMID: 37272327 DOI: 10.1016/j.sbi.2023.102592] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 03/13/2023] [Accepted: 03/16/2023] [Indexed: 06/06/2023]
Abstract
Vacuolar-type ATPases (V-ATPases) are responsible for the acidification of intracellular compartments in almost all eukaryotic cells, while in some specialized cells they acidify the extracellular environment. As ubiquitous proton pumps, these large membrane-embedded enzymes are involved in many fundamental cellular processes that require tight control of pH. Consequently, V-ATPase malfunction or aberrant activity has been linked to numerous diseases. In the past ten years, electron cryomicroscopy (cryoEM) of yeast V-ATPases has revealed the architecture and rotary catalytic mechanism of these macromolecular machines. More recently, studies have revealed the structures of V-ATPases in animals and plants, uncovered aspects of how V-ATPases are assembled and regulated by reversible dissociation, and shown how V-ATPase activity can be modulated by proteins and small molecule inhibitors. In this review, we highlight these recent developments.
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Affiliation(s)
- Hanlin Wang
- Molecular Medicine Program, The Hospital for Sick Children, M5G 0A4, Toronto, Canada; Department of Biochemistry, The University of Toronto, M5G 1L7, Toronto, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, M5G 0A4, Toronto, Canada; Department of Biochemistry, The University of Toronto, M5G 1L7, Toronto, Canada; Department of Medical Biophysics, The University of Toronto, M5S 1A8, Toronto, Canada.
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16
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Sebők-Nagy K, Blastyák A, Juhász G, Páli T. Reversible binding of divalent cations to Ductin protein assemblies-A putative new regulatory mechanism of membrane traffic processes. Front Mol Biosci 2023; 10:1195010. [PMID: 37228584 PMCID: PMC10203432 DOI: 10.3389/fmolb.2023.1195010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 04/24/2023] [Indexed: 05/27/2023] Open
Abstract
Ductins are a family of homologous and structurally similar membrane proteins with 2 or 4 trans-membrane alpha-helices. The active forms of the Ductins are membranous ring- or star-shaped oligomeric assemblies and they provide various pore, channel, gap-junction functions, assist in membrane fusion processes and also serve as the rotor c-ring domain of V-and F-ATPases. All functions of the Ductins have been reported to be sensitive to the presence of certain divalent metal cations (Me2+), most frequently Cu2+ or Ca2+ ions, for most of the better known members of the family, and the mechanism of this effect is not yet known. Given that we have earlier found a prominent Me2+ binding site in a well-characterised Ductin protein, we hypothesise that certain divalent cations can structurally modulate the various functions of Ductin assemblies via affecting their stability by reversible non-covalent binding to them. A fine control of the stability of the assembly ranging from separated monomers through a loosely/weakly to tightly/strongly assembled ring might render precise regulation of Ductin functions possible. The putative role of direct binding of Me2+ to the c-ring subunit of active ATP hydrolase in autophagy and the mechanism of Ca2+-dependent formation of the mitochondrial permeability transition pore are also discussed.
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Affiliation(s)
- Krisztina Sebők-Nagy
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - András Blastyák
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - Gábor Juhász
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - Tibor Páli
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
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17
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Tuli F, Kane PM. Chimeric a-subunit isoforms generate functional yeast V-ATPases with altered regulatory properties in vitro and in vivo. Mol Biol Cell 2023; 34:ar14. [PMID: 36598799 PMCID: PMC10011726 DOI: 10.1091/mbc.e22-07-0265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
V-ATPases are highly regulated proton pumps that acidify organelles. The V-ATPase a-subunit is a two-domain protein containing a C-terminal transmembrane domain responsible for proton transport and an N-terminal cytosolic domain (aNT) that is a regulatory hub, integrating environmental inputs to regulate assembly, localization, and V-ATPase activity. The yeast Saccharomyces cerevisiae encodes only two organelle-specific a-isoforms, Stv1 in the Golgi and Vph1 in the vacuole. On the basis of recent structures, we designed chimeric yeast aNTs in which the globular proximal and distal ends are exchanged. The Vph1 proximal-Stv1 distal (VPSD) aNT chimera binds to the glucose-responsive RAVE assembly factor in vitro but exhibits little binding to PI(3,5)P2. The Stv1 proximal-Vph1 distal (SPVD) aNT lacks RAVE binding but binds more tightly to phosphoinositides than Vph1 or Stv1. When attached to the Vph1 C-terminal domain in vivo, both chimeras complement growth defects of a vph1∆ mutant, but only the SPVD chimera exhibits wild-type V-ATPase activity. Cells containing the SPVD chimera adapt more slowly to a poor carbon source than wild-type cells but grow more rapidly than wild-type cells after a shift to alkaline pH. This is the first example of a "redesigned" V-ATPase with altered regulatory properties and adaptation to specific stresses.
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Affiliation(s)
- Farzana Tuli
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210
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18
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Lévêque C, Maulet Y, Wang Q, Rame M, Rodriguez L, Mochida S, Sangiardi M, Youssouf F, Iborra C, Seagar M, Vitale N, El Far O. A Role for the V0 Sector of the V-ATPase in Neuroexocytosis: Exogenous V0d Blocks Complexin and SNARE Interactions with V0c. Cells 2023; 12:cells12050750. [PMID: 36899886 PMCID: PMC10001230 DOI: 10.3390/cells12050750] [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: 02/07/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/03/2023] Open
Abstract
V-ATPase is an important factor in synaptic vesicle acidification and is implicated in synaptic transmission. Rotation in the extra-membranous V1 sector drives proton transfer through the membrane-embedded multi-subunit V0 sector of the V-ATPase. Intra-vesicular protons are then used to drive neurotransmitter uptake by synaptic vesicles. V0a and V0c, two membrane subunits of the V0 sector, have been shown to interact with SNARE proteins, and their photo-inactivation rapidly impairs synaptic transmission. V0d, a soluble subunit of the V0 sector strongly interacts with its membrane-embedded subunits and is crucial for the canonic proton transfer activity of the V-ATPase. Our investigations show that the loop 1.2 of V0c interacts with complexin, a major partner of the SNARE machinery and that V0d1 binding to V0c inhibits this interaction, as well as V0c association with SNARE complex. The injection of recombinant V0d1 in rat superior cervical ganglion neurons rapidly reduced neurotransmission. In chromaffin cells, V0d1 overexpression and V0c silencing modified in a comparable manner several parameters of unitary exocytotic events. Our data suggest that V0c subunit promotes exocytosis via interactions with complexin and SNAREs and that this activity can be antagonized by exogenous V0d.
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Affiliation(s)
- Christian Lévêque
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Yves Maulet
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, 67000 Strasbourg, France
| | - Marion Rame
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, 67000 Strasbourg, France
| | - Léa Rodriguez
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Sumiko Mochida
- Department of Physiology, Tokyo Medical University, Tokyo 160-8402, Japan
| | - Marion Sangiardi
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Fahamoe Youssouf
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Cécile Iborra
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Michael Seagar
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, 67000 Strasbourg, France
- Correspondence: (N.V.); or (O.E.F.); Tel.: +33-(0)3-8845-6712 (N.V.); +33-(0)4-9169-8860 (O.E.F.)
| | - Oussama El Far
- INSERM UMR_S 1072, 13015 Marseille, France
- Aix-Marseille Université, 13015 Marseille, France
- Correspondence: (N.V.); or (O.E.F.); Tel.: +33-(0)3-8845-6712 (N.V.); +33-(0)4-9169-8860 (O.E.F.)
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19
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Wang Q, Wolf A, Ozkan S, Richert L, Mely Y, Chasserot-Golaz S, Ory S, Gasman S, Vitale N. V-ATPase modulates exocytosis in neuroendocrine cells through the activation of the ARNO-Arf6-PLD pathway and the synthesis of phosphatidic acid. Front Mol Biosci 2023; 10:1163545. [PMID: 37091866 PMCID: PMC10119424 DOI: 10.3389/fmolb.2023.1163545] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/23/2023] [Indexed: 04/25/2023] Open
Abstract
Although there is mounting evidence indicating that lipids serve crucial functions in cells and are implicated in a growing number of human diseases, their precise roles remain largely unknown. This is particularly true in the case of neurosecretion, where fusion with the plasma membrane of specific membrane organelles is essential. Yet, little attention has been given to the role of lipids. Recent groundbreaking research has emphasized the critical role of lipid localization at exocytotic sites and validated the essentiality of fusogenic lipids, such as phospholipase D (PLD)-generated phosphatidic acid (PA), during membrane fusion. Nevertheless, the regulatory mechanisms synchronizing the synthesis of these key lipids and neurosecretion remain poorly understood. The vacuolar ATPase (V-ATPase) has been involved both in vesicle neurotransmitter loading and in vesicle fusion. Thus, it represents an ideal candidate to regulate the fusogenic status of secretory vesicles according to their replenishment state. Indeed, the cytosolic V1 and vesicular membrane-associated V0 subdomains of V-ATPase were shown to dissociate during the stimulation of neurosecretory cells. This allows the subunits of the vesicular V0 to interact with different proteins of the secretory machinery. Here, we show that V0a1 interacts with the Arf nucleotide-binding site opener (ARNO) and promotes the activation of the Arf6 GTPase during the exocytosis in neuroendocrine cells. When the interaction between V0a1 and ARNO was disrupted, it resulted in the inhibition of PLD activation, synthesis of phosphatidic acid during exocytosis, and changes in the timing of fusion events. These findings indicate that the separation of V1 from V0 could function as a signal to initiate the ARNO-Arf6-PLD1 pathway and facilitate the production of phosphatidic acid, which is essential for effective exocytosis in neuroendocrine cells.
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Affiliation(s)
- Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Alexander Wolf
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Sebahat Ozkan
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Ludovic Richert
- Laboratoire de Bioimagerie et Pathologies, Faculté de Pharmacie, CNRS UMR and Université de Strasbourg, Strasbourg, France
| | - Yves Mely
- Laboratoire de Bioimagerie et Pathologies, Faculté de Pharmacie, CNRS UMR and Université de Strasbourg, Strasbourg, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Stéphane Ory
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
- *Correspondence: Nicolas Vitale,
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20
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Filipović D, Costina V, Findeisen P, Inta D. Fluoxetine Enhances Synaptic Vesicle Trafficking and Energy Metabolism in the Hippocampus of Socially Isolated Rats. Int J Mol Sci 2022; 23:ijms232315351. [PMID: 36499675 PMCID: PMC9735484 DOI: 10.3390/ijms232315351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/27/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic social isolation (CSIS)-induced alternation in synaptic and mitochondrial function of specific brain regions is associated with major depressive disorder (MDD). Despite the wide number of available medications, treating MDD remains an important challenge. Although fluoxetine (Flx) is the most frequently prescribed antidepressant, its mode of action is still unknown. To delineate affected molecular pathways of depressive-like behavior and identify potential targets upon Flx treatment, we performed a comparative proteomic analysis of hippocampal purified synaptic terminals (synaptosomes) of rats exposed to six weeks of CSIS, an animal model of depression, and/or followed by Flx treatment (lasting three weeks of six-week CSIS) to explore synaptic protein profile changes. Results showed that Flx in controls mainly induced decreased expression of proteins involved in energy metabolism and the redox system. CSIS led to increased expression of proteins that mainly participate in Ca2+/calmodulin-dependent protein kinase II (Camk2)-related neurotransmission, vesicle transport, and ubiquitination. Flx treatment of CSIS rats predominantly increased expression of proteins involved in synaptic vesicle trafficking (exocytosis and endocytosis), and energy metabolism (glycolytic and mitochondrial respiration). Overall, these Flx-regulated changes in synaptic and mitochondrial proteins of CSIS rats might be critical targets for new therapeutic development for the treatment of MDD.
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Affiliation(s)
- Dragana Filipović
- Department of Molecular Biology and Endocrinology, “VINČA”, Institute of Nuclear Sciences—National Institute of thе Republic of Serbia, University of Belgrade, 11000 Belgrade, Serbia
- Correspondence: ; Tel./Fax: +381-(11)-6455-561
| | - Victor Costina
- Institute for Clinical Chemistry, Medical Faculty Mannheim of the University of Heidelberg, University Hospital Mannheim, 68159 Mannhem, Germany
| | - Peter Findeisen
- Institute for Clinical Chemistry, Medical Faculty Mannheim of the University of Heidelberg, University Hospital Mannheim, 68159 Mannhem, Germany
| | - Dragos Inta
- Department for Community Health Faculty of Natural Sciences, Medicine University of Fribourg, 1700 Fribourg, Switzerland
- Department of Biomedicine, University of Basel, 4052 Basel, Switzerland
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21
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Guerrini R, Mei D, Kerti-Szigeti K, Pepe S, Koenig MK, Von Allmen G, Cho MT, McDonald K, Baker J, Bhambhani V, Powis Z, Rodan L, Nabbout R, Barcia G, Rosenfeld JA, Bacino CA, Mignot C, Power LH, Harris CJ, Marjanovic D, Møller RS, Hammer TB, Keski Filppula R, Vieira P, Hildebrandt C, Sacharow S, Maragliano L, Benfenati F, Lachlan K, Benneche A, Petit F, de Sainte Agathe JM, Hallinan B, Si Y, Wentzensen IM, Zou F, Narayanan V, Matsumoto N, Boncristiano A, la Marca G, Kato M, Anderson K, Barba C, Sturiale L, Garozzo D, Bei R, Masuelli L, Conti V, Novarino G, Fassio A. Phenotypic and genetic spectrum of ATP6V1A encephalopathy: a disorder of lysosomal homeostasis. Brain 2022; 145:2687-2703. [PMID: 35675510 PMCID: PMC10893886 DOI: 10.1093/brain/awac145] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 04/04/2022] [Accepted: 04/07/2022] [Indexed: 11/30/2023] Open
Abstract
Vacuolar-type H+-ATPase (V-ATPase) is a multimeric complex present in a variety of cellular membranes that acts as an ATP-dependent proton pump and plays a key role in pH homeostasis and intracellular signalling pathways. In humans, 22 autosomal genes encode for a redundant set of subunits allowing the composition of diverse V-ATPase complexes with specific properties and expression. Sixteen subunits have been linked to human disease. Here we describe 26 patients harbouring 20 distinct pathogenic de novo missense ATP6V1A variants, mainly clustering within the ATP synthase α/β family-nucleotide-binding domain. At a mean age of 7 years (extremes: 6 weeks, youngest deceased patient to 22 years, oldest patient) clinical pictures included early lethal encephalopathies with rapidly progressive massive brain atrophy, severe developmental epileptic encephalopathies and static intellectual disability with epilepsy. The first clinical manifestation was early hypotonia, in 70%; 81% developed epilepsy, manifested as developmental epileptic encephalopathies in 58% of the cohort and with infantile spasms in 62%; 63% of developmental epileptic encephalopathies failed to achieve any developmental, communicative or motor skills. Less severe outcomes were observed in 23% of patients who, at a mean age of 10 years and 6 months, exhibited moderate intellectual disability, with independent walking and variable epilepsy. None of the patients developed communicative language. Microcephaly (38%) and amelogenesis imperfecta/enamel dysplasia (42%) were additional clinical features. Brain MRI demonstrated hypomyelination and generalized atrophy in 68%. Atrophy was progressive in all eight individuals undergoing repeated MRIs. Fibroblasts of two patients with developmental epileptic encephalopathies showed decreased LAMP1 expression, Lysotracker staining and increased organelle pH, consistent with lysosomal impairment and loss of V-ATPase function. Fibroblasts of two patients with milder disease, exhibited a different phenotype with increased Lysotracker staining, decreased organelle pH and no significant modification in LAMP1 expression. Quantification of substrates for lysosomal enzymes in cellular extracts from four patients revealed discrete accumulation. Transmission electron microscopy of fibroblasts of four patients with variable severity and of induced pluripotent stem cell-derived neurons from two patients with developmental epileptic encephalopathies showed electron-dense inclusions, lipid droplets, osmiophilic material and lamellated membrane structures resembling phospholipids. Quantitative assessment in induced pluripotent stem cell-derived neurons identified significantly smaller lysosomes. ATP6V1A-related encephalopathy represents a new paradigm among lysosomal disorders. It results from a dysfunctional endo-lysosomal membrane protein causing altered pH homeostasis. Its pathophysiology implies intracellular accumulation of substrates whose composition remains unclear, and a combination of developmental brain abnormalities and neurodegenerative changes established during prenatal and early postanal development, whose severity is variably determined by specific pathogenic variants.
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Affiliation(s)
- Renzo Guerrini
- Neuroscience Department, Children's Hospital Meyer, University of Florence, Florence, Italy
| | - Davide Mei
- Neuroscience Department, Children's Hospital Meyer, University of Florence, Florence, Italy
| | | | - Sara Pepe
- Department of Experimental Medicine, University of Genoa, Italy
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
| | - Mary Kay Koenig
- Department of Pediatrics, Division of Child and Adolescent Neurology, The University of Texas McGovern Medical School, Houston, TX, USA
| | - Gretchen Von Allmen
- Department of Pediatrics, Division of Child and Adolescent Neurology, The University of Texas McGovern Medical School, Houston, TX, USA
| | | | - Kimberly McDonald
- Pediatric Neurology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Janice Baker
- Genetics and Genomics, Children's Minnesota, Minneapolis, MN, USA
| | - Vikas Bhambhani
- Genetics and Genomics, Children's Minnesota, Minneapolis, MN, USA
| | - Zöe Powis
- Ambry Genetics, Aliso Viejo, CA, USA
| | - Lance Rodan
- Division of Genetics and Genomics and Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Rima Nabbout
- Reference Centre for Rare Epilepsies, Department of Genetics, Necker Enfants Malades Hospital, APHP, member of ERN EpiCARE, Université de Paris, Paris, France
| | - Giulia Barcia
- Reference Centre for Rare Epilepsies, Department of Genetics, Necker Enfants Malades Hospital, APHP, member of ERN EpiCARE, Université de Paris, Paris, France
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Carlos A Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Cyril Mignot
- APHP, Sorbonne Université, Départément de Génétique, Centre de Référence Déficiences Intellectuelles de Causes Rares, Paris, France
- Institut du Cerveau (ICM), UMR S 1127, Inserm U1127, CNRS UMR 7225, Sorbonne Université, 75013 Paris, France
| | - Lillian H Power
- Pediatric Neurology, Stead Family Department of Pediatrics, University of Iowa Stead Family Children’s Hospital, Iowa City, IA, USA
| | - Catharine J Harris
- Department of Pediatric Genetics, University of Missouri Medical Center, Columbia, MO 65212, USA
| | - Dragan Marjanovic
- Danish Epilepsy Centre Filadelfia, Adult Neurology, Dianalund, Denmark
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund, Denmark
- Department of Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Trine B Hammer
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund, Denmark
| | - The DDD Study
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Riikka Keski Filppula
- Department of Clinical Genetics, Oulu University Hospital, Medical Research Center Oulu and PEDEGO Research Unit, University of Oulu, Oulu, Finland
| | - Päivi Vieira
- Clinic for Children and Adolescents, Oulu University Hospital, Medical Research Center Oulu and PEDEGO Research Unit, University of Oulu, Oulu, Finland
| | - Clara Hildebrandt
- Division of Genetics and Genomics, Metabolism Program, Boston Children's Hospital, Boston, MA, USA
| | | | | | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Katherine Lachlan
- Wessex Clinical Genetics Service, University Hospital Southampton NHS Foundation Trust, Southampton, UK
- Human Development and Health, Faculty of Medicine University of Southampton, Southampton, UK
| | - Andreas Benneche
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | | | - Jean Madeleine de Sainte Agathe
- Laboratoire de Biologie Médicale Multi Sites SeqOIA, Laboratoire de Médecine Génomique, APHP. Sorbonne Université, Paris, France
| | - Barbara Hallinan
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Child Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Yue Si
- GeneDx, Gaithersburg, MD 20877, USA
| | | | | | - Vinodh Narayanan
- Neurogenomics Division, Center for Rare Childhood Disorders, Translational Genomics Research Institute (TGen), Phoenix, AZ 85012, USA
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | | | - Giancarlo la Marca
- Newborn Screening, Clinical Chemistry and Pharmacology Laboratory, Meyer Children’s University Hospital, Florence, Italy
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine and Epilepsy Medical Center, Showa University Hospital, Tokyo, Japan
| | | | - Carmen Barba
- Neuroscience Department, Children's Hospital Meyer, University of Florence, Florence, Italy
| | - Luisa Sturiale
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, 95126 Catania, Italy
| | - Domenico Garozzo
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, 95126 Catania, Italy
| | - Roberto Bei
- Department of Clinical Sciences and Translational Medicine, University of Rome ‘Tor Vergata', Rome, Italy
| | | | - Laura Masuelli
- Department of Experimental Medicine, University of Rome ‘Sapienza', Rome, Italy
| | - Valerio Conti
- Neuroscience Department, Children's Hospital Meyer, University of Florence, Florence, Italy
| | - Gaia Novarino
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Italy
- IRCCS Ospedale Policlinico San Martino, Genova, Italy
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22
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Rechtzigel MJ, Meyerink BL, Leppert H, Johnson TB, Cain JT, Ferrandino G, May DG, Roux KJ, Brudvig JJ, Weimer JM. Transmembrane Batten Disease Proteins Interact With a Shared Network of Vesicle Sorting Proteins, Impacting Their Synaptic Enrichment. Front Neurosci 2022; 16:834780. [PMID: 35692423 PMCID: PMC9174988 DOI: 10.3389/fnins.2022.834780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Batten disease is unique among lysosomal storage disorders for the early and profound manifestation in the central nervous system, but little is known regarding potential neuron-specific roles for the disease-associated proteins. We demonstrate substantial overlap in the protein interactomes of three transmembrane Batten proteins (CLN3, CLN6, and CLN8), and that their absence leads to synaptic depletion of key partners (i.e., SNAREs and tethers) and altered synaptic SNARE complexing in vivo, demonstrating a novel shared etiology.
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Affiliation(s)
| | - Brandon L. Meyerink
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
- Basic Biomedical Sciences, Sanford School of Medicine at the University of South Dakota, Vermillion, SD, United States
| | - Hannah Leppert
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
| | - Tyler B. Johnson
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
| | - Jacob T. Cain
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
| | - Gavin Ferrandino
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
| | - Danielle G. May
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
| | - Kyle J. Roux
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
- Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Vermillion, SD, United States
| | - Jon J. Brudvig
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
- Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Vermillion, SD, United States
| | - Jill M. Weimer
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, United States
- Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Vermillion, SD, United States
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23
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Vasanthakumar T, Keon KA, Bueler SA, Jaskolka MC, Rubinstein JL. Coordinated conformational changes in the V 1 complex during V-ATPase reversible dissociation. Nat Struct Mol Biol 2022; 29:430-439. [PMID: 35469063 DOI: 10.1038/s41594-022-00757-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/03/2022] [Indexed: 11/10/2022]
Abstract
Vacuolar-type ATPases (V-ATPases) are rotary enzymes that acidify intracellular compartments in eukaryotic cells. These multi-subunit complexes consist of a cytoplasmic V1 region that hydrolyzes ATP and a membrane-embedded VO region that transports protons. V-ATPase activity is regulated by reversible dissociation of the two regions, with the isolated V1 and VO complexes becoming autoinhibited on disassembly and subunit C subsequently detaching from V1. In yeast, assembly of the V1 and VO regions is mediated by the regulator of the ATPase of vacuoles and endosomes (RAVE) complex through an unknown mechanism. We used cryogenic-electron microscopy of yeast V-ATPase to determine structures of the intact enzyme, the dissociated but complete V1 complex and the V1 complex lacking subunit C. On separation, V1 undergoes a dramatic conformational rearrangement, with its rotational state becoming incompatible for reassembly with VO. Loss of subunit C allows V1 to match the rotational state of VO, suggesting how RAVE could reassemble V1 and VO by recruiting subunit C.
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Affiliation(s)
- Thamiya Vasanthakumar
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada
| | - Kristine A Keon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada. .,Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada.
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24
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Satarker S, Bojja SL, Gurram PC, Mudgal J, Arora D, Nampoothiri M. Astrocytic Glutamatergic Transmission and Its Implications in Neurodegenerative Disorders. Cells 2022; 11:cells11071139. [PMID: 35406702 PMCID: PMC8997779 DOI: 10.3390/cells11071139] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/12/2022] [Accepted: 03/13/2022] [Indexed: 12/11/2022] Open
Abstract
Several neurodegenerative disorders involve impaired neurotransmission, and glutamatergic neurotransmission sets a prototypical example. Glutamate is a predominant excitatory neurotransmitter where the astrocytes play a pivotal role in maintaining the extracellular levels through release and uptake mechanisms. Astrocytes modulate calcium-mediated excitability and release several neurotransmitters and neuromodulators, including glutamate, and significantly modulate neurotransmission. Accumulating evidence supports the concept of excitotoxicity caused by astrocytic glutamatergic release in pathological conditions. Thus, the current review highlights different vesicular and non-vesicular mechanisms of astrocytic glutamate release and their implication in neurodegenerative diseases. As in presynaptic neurons, the vesicular release of astrocytic glutamate is also primarily meditated by calcium-mediated exocytosis. V-ATPase is crucial in the acidification and maintenance of the gradient that facilitates the vesicular storage of glutamate. Along with these, several other components, such as cystine/glutamate antiporter, hemichannels, BEST-1, TREK-1, purinergic receptors and so forth, also contribute to glutamate release under physiological and pathological conditions. Events of hampered glutamate uptake could promote inflamed astrocytes to trigger repetitive release of glutamate. This could be favorable towards the development and worsening of neurodegenerative diseases. Therefore, across neurodegenerative diseases, we review the relations between defective glutamatergic signaling and astrocytic vesicular and non-vesicular events in glutamate homeostasis. The optimum regulation of astrocytic glutamatergic transmission could pave the way for the management of these diseases and add to their therapeutic value.
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Affiliation(s)
- Sairaj Satarker
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Sree Lalitha Bojja
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Prasada Chowdari Gurram
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Jayesh Mudgal
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Devinder Arora
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Madhavan Nampoothiri
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- Correspondence:
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25
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Maxson ME, Abbas YM, Wu JZ, Plumb JD, Grinstein S, Rubinstein JL. Detection and quantification of the vacuolar H+ATPase using the Legionella effector protein SidK. J Biophys Biochem Cytol 2022; 221:212963. [PMID: 35024770 PMCID: PMC8763849 DOI: 10.1083/jcb.202107174] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 12/14/2021] [Accepted: 12/21/2021] [Indexed: 12/11/2022] Open
Abstract
Acidification of secretory and endocytic organelles is required for proper receptor recycling, membrane traffic, protein degradation, and solute transport. Proton-pumping vacuolar H+ ATPases (V-ATPases) are responsible for this luminal acidification, which increases progressively as secretory and endocytic vesicles mature. An increasing density of V-ATPase complexes is thought to account for the gradual decrease in pH, but available reagents have not been sufficiently sensitive or specific to test this hypothesis. We introduce a new probe to localize and quantify V-ATPases. The probe is derived from SidK, a Legionella pneumophila effector protein that binds to the V-ATPase A subunit. We generated plasmids encoding fluorescent chimeras of SidK1-278, and labeled recombinant SidK1-278 with Alexa Fluor 568 to visualize and quantify V-ATPases with high specificity in live and fixed cells, respectively. We show that V-ATPases are acquired progressively during phagosome maturation, that they distribute in discrete membrane subdomains, and that their density in lysosomes depends on their subcellular localization.
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Affiliation(s)
- Michelle E Maxson
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
| | - Yazan M Abbas
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Jing Ze Wu
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Jonathan D Plumb
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
| | - Sergio Grinstein
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - John L Rubinstein
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
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26
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Khan MM, Lee S, Couoh-Cardel S, Oot RA, Kim H, Wilkens S, Roh SH. Oxidative stress protein Oxr1 promotes V-ATPase holoenzyme disassembly in catalytic activity-independent manner. EMBO J 2021; 41:e109360. [PMID: 34918374 PMCID: PMC8804929 DOI: 10.15252/embj.2021109360] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/30/2021] [Accepted: 11/15/2021] [Indexed: 11/09/2022] Open
Abstract
The vacuolar ATPase (V-ATPase) is a rotary motor proton pump that is regulated by an assembly equilibrium between active holoenzyme and autoinhibited V1 -ATPase and Vo proton channel subcomplexes. Here, we report cryo-EM structures of yeast V-ATPase assembled in vitro from lipid nanodisc reconstituted Vo and mutant V1 . Our analysis identified holoenzymes in three active rotary states, indicating that binding of V1 to Vo provides sufficient free energy to overcome Vo autoinhibition. Moreover, the structures suggest that the unequal spacing of Vo 's proton-carrying glutamic acid residues serves to alleviate the symmetry mismatch between V1 and Vo motors, a notion that is supported by mutagenesis experiments. We also uncover a structure of free V1 bound to Oxr1, a conserved but poorly characterized factor involved in the oxidative stress response. Biochemical experiments show that Oxr1 inhibits V1 -ATPase and causes disassembly of the holoenzyme, suggesting that Oxr1 plays a direct role in V-ATPase regulation.
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Affiliation(s)
- Md Murad Khan
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Seowon Lee
- School of Biological Science, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Sergio Couoh-Cardel
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Rebecca A Oot
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Hyunmin Kim
- School of Biological Science, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Soung-Hun Roh
- School of Biological Science, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
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27
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Eaton AF, Brown D, Merkulova M. The evolutionary conserved TLDc domain defines a new class of (H +)V-ATPase interacting proteins. Sci Rep 2021; 11:22654. [PMID: 34811399 PMCID: PMC8608904 DOI: 10.1038/s41598-021-01809-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 11/02/2021] [Indexed: 01/26/2023] Open
Abstract
We recently found that nuclear receptor coactivator 7 (Ncoa7) and Oxr1 interact with the proton-pumping V-ATPase. Ncoa7 and Oxr1 belong to a group of proteins playing a role in the oxidative stress response, that contain the conserved “TLDc” domain. Here we asked if the three other proteins in this family, i.e., Tbc1d24, Tldc1 and Tldc2 also interact with the V-ATPase and if the TLDc domains are involved in all these interactions. By co-immunoprecipitation, endogenous kidney Tbc1d24 (and Ncoa7 and Oxr1) and overexpressed Tldc1 and Tldc2, all interacted with the V-ATPase. In addition, purified TLDc domains of Ncoa7, Oxr1 and Tldc2 (but not Tbc1d24 or Tldc1) interacted with V-ATPase in GST pull-downs. At the amino acid level, point mutations G815A, G845A and G896A in conserved regions of the Ncoa7 TLDc domain abolished interaction with the V-ATPase, and S817A, L926A and E938A mutations resulted in decreased interaction. Furthermore, poly-E motifs upstream of the TLDc domain in Ncoa7 and Tldc2 show a (nonsignificant) trend towards enhancing the interaction with V-ATPase. Our principal finding is that all five members of the TLDc family of proteins interact with the V-ATPase. We conclude that the TLDc motif defines a new class of V-ATPase interacting regulatory proteins.
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Affiliation(s)
- A F Eaton
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
| | - D Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
| | - M Merkulova
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA. .,Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, Simches Research Center, 128 Cambridge St., Boston, MA, 02114, USA.
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28
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A Novel Neuron-Specific Regulator of the V-ATPase in Drosophila. eNeuro 2021; 8:ENEURO.0193-21.2021. [PMID: 34620624 PMCID: PMC8541823 DOI: 10.1523/eneuro.0193-21.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 08/24/2021] [Accepted: 09/30/2021] [Indexed: 12/15/2022] Open
Abstract
The V-ATPase is a highly conserved enzymatic complex that ensures appropriate levels of organelle acidification in virtually all eukaryotic cells. While the general mechanisms of this proton pump have been well studied, little is known about the specific regulations of neuronal V-ATPase. Here, we studied CG31030, a previously uncharacterized Drosophila protein predicted from its sequence homology to be part of the V-ATPase family. In contrast to its ortholog ATP6AP1/VhaAC45 which is ubiquitous, we observed that CG31030 expression is apparently restricted to all neurons, and using CRISPR/Cas9-mediated gene tagging, that it is mainly addressed to synaptic terminals. In addition, we observed that CG31030 is essential for fly survival and that this protein co-immunoprecipitates with identified V-ATPase subunits, and in particular ATP6AP2. Using a genetically-encoded pH probe (VMAT-pHluorin) and electrophysiological recordings at the larval neuromuscular junction, we show that CG31030 knock-down induces a major defect in synaptic vesicle acidification and a decrease in quantal size, which is the amplitude of the postsynaptic response to the release of a single synaptic vesicle. These defects were associated with severe locomotor impairments. Overall, our data indicate that CG31030, which we renamed VhaAC45-related protein (VhaAC45RP), is a specific regulator of neuronal V-ATPase in Drosophila that is required for proper synaptic vesicle acidification and neurotransmitter release.
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Oot RA, Yao Y, Manolson MF, Wilkens S. Purification of active human vacuolar H +-ATPase in native lipid-containing nanodiscs. J Biol Chem 2021; 297:100964. [PMID: 34270960 PMCID: PMC8353480 DOI: 10.1016/j.jbc.2021.100964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/07/2021] [Accepted: 07/12/2021] [Indexed: 12/26/2022] Open
Abstract
Vacuolar H+-ATPases (V-ATPases) are large, multisubunit proton pumps that acidify the lumen of organelles in virtually every eukaryotic cell and in specialized acid-secreting animal cells, the enzyme pumps protons into the extracellular space. In higher organisms, most of the subunits are expressed as multiple isoforms, with some enriched in specific compartments or tissues and others expressed ubiquitously. In mammals, subunit a is expressed as four isoforms (a1-4) that target the enzyme to distinct biological membranes. Mutations in a isoforms are known to give rise to tissue-specific disease, and some a isoforms are upregulated and mislocalized to the plasma membrane in invasive cancers. However, isoform complexity and low abundance greatly complicate purification of active human V-ATPase, a prerequisite for developing isoform-specific therapeutics. Here, we report the purification of an active human V-ATPase in native lipid nanodiscs from a cell line stably expressing affinity-tagged a isoform 4 (a4). We find that exogenous expression of this single subunit in HEK293F cells permits assembly of a functional V-ATPase by incorporation of endogenous subunits. The ATPase activity of the preparation is >95% sensitive to concanamycin A, indicating that the lipid nanodisc-reconstituted enzyme is functionally coupled. Moreover, this strategy permits purification of the enzyme's isolated membrane subcomplex together with biosynthetic assembly factors coiled-coil domain-containing protein 115, transmembrane protein 199, and vacuolar H+-ATPase assembly integral membrane protein 21. Our work thus lays the groundwork for biochemical characterization of active human V-ATPase in an a subunit isoform-specific manner and establishes a platform for the study of the assembly and regulation of the human holoenzyme.
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Affiliation(s)
- Rebecca A Oot
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Yeqi Yao
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Morris F Manolson
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA.
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30
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Genetic architecture and phenotypic landscape of deafness and onychodystrophy syndromes. Hum Genet 2021; 141:821-838. [PMID: 34232384 DOI: 10.1007/s00439-021-02310-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Deafness and onychodystrophy syndromes are a group of phenotypically overlapping syndromes, which include DDOD syndrome (dominant deafness-onychodystrophy), DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation and seizures) and Zimmermann-Laband syndrome (gingival hypertrophy, coarse facial features, hypoplasia or aplasia of nails and terminal phalanges, intellectual disability, and hypertrichosis). Pathogenic variants in four genes, ATP6V1B2, TBC1D24, KCNH1 and KCNN3, have been shown to be associated with deafness and onychodystrophy syndromes. ATP6V1B2 encodes a component of the vacuolar H+-ATPase (V-ATPase) and TBC1D24 belongs to GTPase-activating protein, which are all involved in the regulation of membrane trafficking. The overlapping clinical phenotype of TBC1D24- and ATP6V1B2- related diseases and their function with GTPases or ATPases activity indicate that they may have some physiological link. Variants in genes encoding potassium channels KCNH1 or KCNN3, underlying human Zimmermann-Laband syndrome, have only recently been recognized. Although further analysis will be needed, these findings will help to elucidate an understanding of the pathogenesis of these disorders better and will aid in the development of potential therapeutic approaches. In this review, we summarize the latest developments of clinical features and molecular basis that have been reported to be associated with deafness and onychodystrophy disorders and highlight the challenges that may arise in the differential diagnosis.
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Jaskolka MC, Winkley SR, Kane PM. RAVE and Rabconnectin-3 Complexes as Signal Dependent Regulators of Organelle Acidification. Front Cell Dev Biol 2021; 9:698190. [PMID: 34249946 PMCID: PMC8264551 DOI: 10.3389/fcell.2021.698190] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/28/2021] [Indexed: 12/12/2022] Open
Abstract
The yeast RAVE (Regulator of H+-ATPase of Vacuolar and Endosomal membranes) complex and Rabconnectin-3 complexes of higher eukaryotes regulate acidification of organelles such as lysosomes and endosomes by catalyzing V-ATPase assembly. V-ATPases are highly conserved proton pumps consisting of a peripheral V1 subcomplex that contains the sites of ATP hydrolysis, attached to an integral membrane Vo subcomplex that forms the transmembrane proton pore. Reversible disassembly of the V-ATPase is a conserved regulatory mechanism that occurs in response to multiple signals, serving to tune ATPase activity and compartment acidification to changing extracellular conditions. Signals such as glucose deprivation can induce release of V1 from Vo, which inhibits both ATPase activity and proton transport. Reassembly of V1 with Vo restores ATP-driven proton transport, but requires assistance of the RAVE or Rabconnectin-3 complexes. Glucose deprivation triggers V-ATPase disassembly in yeast and is accompanied by binding of RAVE to V1 subcomplexes. Upon glucose readdition, RAVE catalyzes both recruitment of V1 to the vacuolar membrane and its reassembly with Vo. The RAVE complex can be recruited to the vacuolar membrane by glucose in the absence of V1 subunits, indicating that the interaction between RAVE and the Vo membrane domain is glucose-sensitive. Yeast RAVE complexes also distinguish between organelle-specific isoforms of the Vo a-subunit and thus regulate distinct V-ATPase subpopulations. Rabconnectin-3 complexes in higher eukaryotes appear to be functionally equivalent to yeast RAVE. Originally isolated as a two-subunit complex from rat brain, the Rabconnectin-3 complex has regions of homology with yeast RAVE and was shown to interact with V-ATPase subunits and promote endosomal acidification. Current understanding of the structure and function of RAVE and Rabconnectin-3 complexes, their interactions with the V-ATPase, their role in signal-dependent modulation of organelle acidification, and their impact on downstream pathways will be discussed.
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Affiliation(s)
- Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Samuel R Winkley
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
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32
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Novel vertebrate- and brain-specific driver of neuronal outgrowth. Prog Neurobiol 2021; 202:102069. [PMID: 33933532 DOI: 10.1016/j.pneurobio.2021.102069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 03/31/2021] [Accepted: 04/21/2021] [Indexed: 12/30/2022]
Abstract
During the process of neuronal outgrowth, developing neurons produce new projections, neurites, that are essential for brain wiring. Here, we discover a relatively late-evolved protein that we denote Ac45-related protein (Ac45RP) and that, surprisingly, drives neuronal outgrowth. Ac45RP is a paralog of the Ac45 protein that is a component of the vacuolar proton ATPase (V-ATPase), the main pH regulator in eukaryotic cells. Ac45RP mRNA expression is brain specific and coincides with the peak of neurogenesis and the onset of synaptogenesis. Furthermore, Ac45RP physically interacts with the V-ATPase V0-sector and colocalizes with V0 in unconventional, but not synaptic, secretory vesicles of extending neurites. Excess Ac45RP enhances the expression of V0-subunits, causes a more elaborate Golgi, and increases the number of cytoplasmic vesicular structures, plasma membrane formation and outgrowth of actin-containing neurites devoid of synaptic markers. CRISPR-cas9n-mediated Ac45RP knockdown reduces neurite outgrowth. We conclude that the novel vertebrate- and brain-specific Ac45RP is a V0-interacting constituent of unconventional vesicular structures that drives membrane expansion during neurite outgrowth and as such may furnish a tool for future neuroregenerative treatment strategies.
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33
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Jaskolka MC, Tarsio M, Smardon AM, Khan MM, Kane PM. Defining steps in RAVE-catalyzed V-ATPase assembly using purified RAVE and V-ATPase subcomplexes. J Biol Chem 2021; 296:100703. [PMID: 33895134 PMCID: PMC8138766 DOI: 10.1016/j.jbc.2021.100703] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/30/2022] Open
Abstract
The vacuolar H+-ATPase (V-ATPase) is a highly conserved proton pump responsible for the acidification of intracellular organelles in virtually all eukaryotic cells. V-ATPases are regulated by the rapid and reversible disassembly of the peripheral V1 domain from the integral membrane Vo domain, accompanied by release of the V1 C subunit from both domains. Efficient reassembly of V-ATPases requires the Regulator of the H+-ATPase of Vacuoles and Endosomes (RAVE) complex in yeast. Although a number of pairwise interactions between RAVE and V-ATPase subunits have been mapped, the low endogenous levels of the RAVE complex and lethality of constitutive RAV1 overexpression have hindered biochemical characterization of the intact RAVE complex. We describe a novel inducible overexpression system that allows purification of native RAVE and RAVE–V1 complexes. Both purified RAVE and RAVE–V1 contain substoichiometric levels of subunit C. RAVE–V1 binds tightly to expressed subunit C in vitro, but binding of subunit C to RAVE alone is weak. Neither RAVE nor RAVE–V1 interacts with the N-terminal domain of Vo subunit Vph1 in vitro. RAVE–V1 complexes, like isolated V1, have no MgATPase activity, suggesting that RAVE cannot reverse V1 inhibition generated by rotation of subunit H and entrapment of MgADP that occur upon disassembly. However, purified RAVE can accelerate reassembly of V1 carrying a mutant subunit H incapable of inhibition with Vo complexes reconstituted into lipid nanodiscs, consistent with its catalytic activity in vivo. These results provide new insights into the possible order of events in V-ATPase reassembly and the roles of the RAVE complex in each event.
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Affiliation(s)
- Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Maureen Tarsio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Anne M Smardon
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Md Murad Khan
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA.
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34
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Aoto K, Kato M, Akita T, Nakashima M, Mutoh H, Akasaka N, Tohyama J, Nomura Y, Hoshino K, Ago Y, Tanaka R, Epstein O, Ben-Haim R, Heyman E, Miyazaki T, Belal H, Takabayashi S, Ohba C, Takata A, Mizuguchi T, Miyatake S, Miyake N, Fukuda A, Matsumoto N, Saitsu H. ATP6V0A1 encoding the a1-subunit of the V0 domain of vacuolar H +-ATPases is essential for brain development in humans and mice. Nat Commun 2021; 12:2107. [PMID: 33833240 PMCID: PMC8032687 DOI: 10.1038/s41467-021-22389-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 03/05/2021] [Indexed: 02/01/2023] Open
Abstract
Vacuolar H+-ATPases (V-ATPases) transport protons across cellular membranes to acidify various organelles. ATP6V0A1 encodes the a1-subunit of the V0 domain of V-ATPases, which is strongly expressed in neurons. However, its role in brain development is unknown. Here we report four individuals with developmental and epileptic encephalopathy with ATP6V0A1 variants: two individuals with a de novo missense variant (R741Q) and the other two individuals with biallelic variants comprising one almost complete loss-of-function variant and one missense variant (A512P and N534D). Lysosomal acidification is significantly impaired in cell lines expressing three missense ATP6V0A1 mutants. Homozygous mutant mice harboring human R741Q (Atp6v0a1R741Q) and A512P (Atp6v0a1A512P) variants show embryonic lethality and early postnatal mortality, respectively, suggesting that R741Q affects V-ATPase function more severely. Lysosomal dysfunction resulting in cell death, accumulated autophagosomes and lysosomes, reduced mTORC1 signaling and synaptic connectivity, and lowered neurotransmitter contents of synaptic vesicles are observed in the brains of Atp6v0a1A512P/A512P mice. These findings demonstrate the essential roles of ATP6V0A1/Atp6v0a1 in neuronal development in terms of integrity and connectivity of neurons in both humans and mice. A member of the vacuolar H+-ATPase family, ATP6V0A1 is involved in lysosomal activity. Here, the authors report that ATP6V0A1 variants identified in individuals with developmental and epileptic encephalopathy are associated with impairment of lysosomal acidification, autophagy and mTORC1 signaling, suggesting an essential role of ATP6V0A1 in brain development.
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Affiliation(s)
- Kazushi Aoto
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan.
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Mitsuko Nakashima
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hiroki Mutoh
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Noriyuki Akasaka
- Department of Child Neurology, National Hospital Organization Nishiniigata Chuo Hospital, Niigata, Japan.,Department of Pediatrics, Niigata Prefecture Hamagumi Medical Rehabilitation Center for Disabled Children, Niigata, Japan
| | - Jun Tohyama
- Department of Child Neurology, National Hospital Organization Nishiniigata Chuo Hospital, Niigata, Japan
| | - Yoshiko Nomura
- Segawa Neurological Clinic for Children, Tokyo, Japan.,Yoshiko Nomura Neurological Clinic for Children, Tokyo, Japan
| | - Kyoko Hoshino
- Segawa Neurological Clinic for Children, Tokyo, Japan.,Segawa Memorial Neurological Clinic for Children, Tokyo, Japan
| | - Yasuhiko Ago
- Department of Neonatology, Ibaraki Children's Hospital, Mito, Japan.,Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Ryuta Tanaka
- Ibaraki Pediatric Education and Training Station, University of Tsukuba, Mito, Japan
| | - Orna Epstein
- Pediatric Neurology and Development Center, Shamir Medical Center, Tzrifin, Beer Yaakov, Israel
| | - Revital Ben-Haim
- Pediatric Neurology and Development Center, Shamir Medical Center, Tzrifin, Beer Yaakov, Israel
| | - Eli Heyman
- Pediatric Neurology and Development Center, Shamir Medical Center, Tzrifin, Beer Yaakov, Israel
| | - Takehiro Miyazaki
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hazrat Belal
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Shuji Takabayashi
- Laboratory Animal Facilities & Services, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Chihiro Ohba
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Atsushi Takata
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Takeshi Mizuguchi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan.
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35
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Wittig S, Ganzella M, Barth M, Kostmann S, Riedel D, Pérez-Lara Á, Jahn R, Schmidt C. Cross-linking mass spectrometry uncovers protein interactions and functional assemblies in synaptic vesicle membranes. Nat Commun 2021; 12:858. [PMID: 33558502 PMCID: PMC7870876 DOI: 10.1038/s41467-021-21102-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/18/2020] [Indexed: 02/08/2023] Open
Abstract
Synaptic vesicles are storage organelles for neurotransmitters. They pass through a trafficking cycle and fuse with the pre-synaptic membrane when an action potential arrives at the nerve terminal. While molecular components and biophysical parameters of synaptic vesicles have been determined, our knowledge on the protein interactions in their membranes is limited. Here, we apply cross-linking mass spectrometry to study interactions of synaptic vesicle proteins in an unbiased approach without the need for specific antibodies or detergent-solubilisation. Our large-scale analysis delivers a protein network of vesicle sub-populations and functional assemblies including an active and an inactive conformation of the vesicular ATPase complex as well as non-conventional arrangements of the luminal loops of SV2A, Synaptophysin and structurally related proteins. Based on this network, we specifically target Synaptobrevin-2, which connects with many proteins, in different approaches. Our results allow distinction of interactions caused by 'crowding' in the vesicle membrane from stable interaction modules.
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Affiliation(s)
- Sabine Wittig
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Marcelo Ganzella
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marie Barth
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Susann Kostmann
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Dietmar Riedel
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ángel Pérez-Lara
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Reinhard Jahn
- Department for Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Carla Schmidt
- Interdisciplinary Research Centre HALOmem, Charles Tanford Protein Centre, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany.
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36
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Santos-Pereira C, Rodrigues LR, Côrte-Real M. Emerging insights on the role of V-ATPase in human diseases: Therapeutic challenges and opportunities. Med Res Rev 2021; 41:1927-1964. [PMID: 33483985 DOI: 10.1002/med.21782] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/05/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022]
Abstract
The control of the intracellular pH is vital for the survival of all organisms. Membrane transporters, both at the plasma and intracellular membranes, are key players in maintaining a finely tuned pH balance between intra- and extracellular spaces, and therefore in cellular homeostasis. V-ATPase is a housekeeping ATP-driven proton pump highly conserved among prokaryotes and eukaryotes. This proton pump, which exhibits a complex multisubunit structure based on cell type-specific isoforms, is essential for pH regulation and for a multitude of ubiquitous and specialized functions. Thus, it is not surprising that V-ATPase aberrant overexpression, mislocalization, and mutations in V-ATPase subunit-encoding genes have been associated with several human diseases. However, the ubiquitous expression of this transporter and the high toxicity driven by its off-target inhibition, renders V-ATPase-directed therapies very challenging and increases the need for selective strategies. Here we review emerging evidence linking V-ATPase and both inherited and acquired human diseases, explore the therapeutic challenges and opportunities envisaged from recent data, and advance future research avenues. We highlight the importance of V-ATPases with unique subunit isoform molecular signatures and disease-associated isoforms to design selective V-ATPase-directed therapies. We also discuss the rational design of drug development pipelines and cutting-edge methodological approaches toward V-ATPase-centered drug discovery. Diseases like cancer, osteoporosis, and even fungal infections can benefit from V-ATPase-directed therapies.
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Affiliation(s)
- Cátia Santos-Pereira
- Department of Biology, Centre of Molecular and Environmental Biology (CBMA), University of Minho, Braga, Portugal.,Department of Biological Engineering, Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
| | - Lígia R Rodrigues
- Department of Biological Engineering, Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
| | - Manuela Côrte-Real
- Department of Biology, Centre of Molecular and Environmental Biology (CBMA), University of Minho, Braga, Portugal
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37
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Eaton AF, Merkulova M, Brown D. The H +-ATPase (V-ATPase): from proton pump to signaling complex in health and disease. Am J Physiol Cell Physiol 2020; 320:C392-C414. [PMID: 33326313 PMCID: PMC8294626 DOI: 10.1152/ajpcell.00442.2020] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A primary function of the H+-ATPase (or V-ATPase) is to create an electrochemical proton gradient across eukaryotic cell membranes, which energizes fundamental cellular processes. Its activity allows for the acidification of intracellular vesicles and organelles, which is necessary for many essential cell biological events to occur. In addition, many specialized cell types in various organ systems such as the kidney, bone, male reproductive tract, inner ear, olfactory mucosa, and more, use plasma membrane V-ATPases to perform specific activities that depend on extracellular acidification. It is, however, increasingly apparent that V-ATPases are central players in many normal and pathophysiological processes that directly influence human health in many different and sometimes unexpected ways. These include cancer, neurodegenerative diseases, diabetes, and sensory perception, as well as energy and nutrient-sensing functions within cells. This review first covers the well-established role of the V-ATPase as a transmembrane proton pump in the plasma membrane and intracellular vesicles and outlines factors contributing to its physiological regulation in different cell types. This is followed by a discussion of the more recently emerging unconventional roles for the V-ATPase, such as its role as a protein interaction hub involved in cell signaling, and the (patho)physiological implications of these interactions. Finally, the central importance of endosomal acidification and V-ATPase activity on viral infection will be discussed in the context of the current COVID-19 pandemic.
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Affiliation(s)
- Amity F Eaton
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Maria Merkulova
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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38
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The ATPase subunit of ATP6V1C1 inhibits autophagy and enhances radiotherapy resistance in esophageal squamous cell carcinoma. Gene 2020; 768:145261. [PMID: 33183740 DOI: 10.1016/j.gene.2020.145261] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 10/20/2020] [Indexed: 01/20/2023]
Abstract
Radiotherapy is one of the primary therapeutic modalities for patients diagnosed esophageal squamous cell carcinoma(ESCC). Previous studies have shown that chemotherapy resistance could be linked with the overexpression vascular ATPases(V-ATPase) subunits genes. However, it is unknown whether V-ATPase subunits genes play a role in radiotherapy resistance. The aim of this study was to investigate the effect of the ATP6V1C1 in radiotherapy resistance. siRNA and plasmids were used to transfect low expression of ATP6V1C1 in TE13 (human ESCC cell) and high expressed in ECA109 (human ESCC cell), respectively. To observe proliferation, radiosensitivity, apoptosis and DNA-damage response, colony formation assays, EDU assays, flow cytometry and γH2AX assay were used with or without radiation exposure, separately. The quantities of the autophagosomes and autolysosomes by immunofluorescence were calculated. Autophagic microstructure were discovered by transmission electron microscopy, and the study also repeated in vivo by nude mice. Western blot assay was applied to prove changes in relative proteins. We found that suppressing ATP6V1C1 increased the sensitivity of ESCC cells after RT. Silencing ATP6V1C1 with IR suppressed the tumor growth and promoted autophagy. Besides, the underlying mechanism of ATP6V1C1, which is not fatally disrupted, is that ATP6V1C1 with ionizing radiation (IR)decreased apoptosis and inhibited autophagy may by activating mTOR signaling to suppress radiosensitivity for ESCC cells. Thus, we first reported that the ATP6V1C1 may represent a potential radiotherapeutic target by effect on radiation sensitivity for ESCC.
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39
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Jiang L, Wang M, Lin S, Jian R, Li X, Chan J, Dong G, Fang H, Robinson AE, Snyder MP. A Quantitative Proteome Map of the Human Body. Cell 2020; 183:269-283.e19. [PMID: 32916130 PMCID: PMC7575058 DOI: 10.1016/j.cell.2020.08.036] [Citation(s) in RCA: 211] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/14/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023]
Abstract
Determining protein levels in each tissue and how they compare with RNA levels is important for understanding human biology and disease as well as regulatory processes that control protein levels. We quantified the relative protein levels from over 12,000 genes across 32 normal human tissues. Tissue-specific or tissue-enriched proteins were identified and compared to transcriptome data. Many ubiquitous transcripts are found to encode tissue-specific proteins. Discordance of RNA and protein enrichment revealed potential sites of synthesis and action of secreted proteins. The tissue-specific distribution of proteins also provides an in-depth view of complex biological events that require the interplay of multiple tissues. Most importantly, our study demonstrated that protein tissue-enrichment information can explain phenotypes of genetic diseases, which cannot be obtained by transcript information alone. Overall, our results demonstrate how understanding protein levels can provide insights into regulation, secretome, metabolism, and human diseases.
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Affiliation(s)
- Lihua Jiang
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Meng Wang
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Shin Lin
- Division of Cardiology, University of Washington, Seattle, WA 98195, USA
| | - Ruiqi Jian
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Xiao Li
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Joanne Chan
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Guanlan Dong
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Huaying Fang
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Aaron E Robinson
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Michael P Snyder
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
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40
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Bonnycastle K, Davenport EC, Cousin MA. Presynaptic dysfunction in neurodevelopmental disorders: Insights from the synaptic vesicle life cycle. J Neurochem 2020; 157:179-207. [PMID: 32378740 DOI: 10.1111/jnc.15035] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 12/11/2022]
Abstract
The activity-dependent fusion, retrieval and recycling of synaptic vesicles is essential for the maintenance of neurotransmission. Until relatively recently it was believed that most mutations in genes that were essential for this process would be incompatible with life, because of this fundamental role. However, an ever-expanding number of mutations in this very cohort of genes are being identified in individuals with neurodevelopmental disorders, including autism, intellectual disability and epilepsy. This article will summarize the current state of knowledge linking mutations in presynaptic genes to neurodevelopmental disorders by sequentially covering the various stages of the synaptic vesicle life cycle. It will also discuss how perturbations of specific stages within this recycling process could translate into human disease. Finally, it will also provide perspectives on the potential for future therapy that are targeted to presynaptic function.
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Affiliation(s)
- Katherine Bonnycastle
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
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41
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Banerjee S, Kane PM. Regulation of V-ATPase Activity and Organelle pH by Phosphatidylinositol Phosphate Lipids. Front Cell Dev Biol 2020; 8:510. [PMID: 32656214 PMCID: PMC7324685 DOI: 10.3389/fcell.2020.00510] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/28/2020] [Indexed: 12/14/2022] Open
Abstract
Luminal pH and the distinctive distribution of phosphatidylinositol phosphate (PIP) lipids are central identifying features of organelles in all eukaryotic cells that are also critical for organelle function. V-ATPases are conserved proton pumps that populate and acidify multiple organelles of the secretory and the endocytic pathway. Complete loss of V-ATPase activity causes embryonic lethality in higher animals and conditional lethality in yeast, while partial loss of V-ATPase function is associated with multiple disease states. On the other hand, many cancer cells increase their virulence by upregulating V-ATPase expression and activity. The pH of individual organelles is tightly controlled and essential for function, but the mechanisms for compartment-specific pH regulation are not completely understood. There is substantial evidence indicating that the PIP content of membranes influences organelle pH. We present recent evidence that PIPs interact directly with subunit isoforms of the V-ATPase to dictate localization of V-ATPase subpopulations and participate in their regulation. In yeast cells, which have only one set of organelle-specific V-ATPase subunit isoforms, the Golgi-enriched lipid PI(4)P binds to the cytosolic domain of the Golgi-enriched a-subunit isoform Stv1, and loss of PI(4)P binding results in mislocalization of Stv1-containing V-ATPases from the Golgi to the vacuole/lysosome. In contrast, levels of the vacuole/lysosome-enriched signaling lipid PI(3,5)P2 affect assembly and activity of V-ATPases containing the Vph1 a-subunit isoform. Mutations in the Vph1 isoform that disrupt the lipid interaction increase sensitivity to stress. These studies have decoded “zip codes” for PIP lipids in the cytosolic N-terminal domain of the a-subunit isoforms of the yeast V-ATPase, and similar interactions between PIP lipids and the V-ATPase subunit isoforms are emerging in higher eukaryotes. In addition to direct effects on the V-ATPase, PIP lipids are also likely to affect organelle pH indirectly, through interactions with other membrane transporters. We discuss direct and indirect effects of PIP lipids on organelle pH, and the functional consequences of the interplay between PIP lipid content and organelle pH.
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Affiliation(s)
- Subhrajit Banerjee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
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42
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Collins MP, Forgac M. Regulation and function of V-ATPases in physiology and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183341. [PMID: 32422136 DOI: 10.1016/j.bbamem.2020.183341] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 02/07/2023]
Abstract
The vacuolar H+-ATPases (V-ATPases) are essential, ATP-dependent proton pumps present in a variety of eukaryotic cellular membranes. Intracellularly, V-ATPase-dependent acidification functions in such processes as membrane traffic, protein degradation, autophagy and the coupled transport of small molecules. V-ATPases at the plasma membrane of certain specialized cells function in such processes as bone resorption, sperm maturation and urinary acidification. V-ATPases also function in disease processes such as pathogen entry and cancer cell invasiveness, while defects in V-ATPase genes are associated with disorders such as osteopetrosis, renal tubular acidosis and neurodegenerative diseases. This review highlights recent advances in our understanding of V-ATPase structure, mechanism, function and regulation, with an emphasis on the signaling pathways controlling V-ATPase assembly in mammalian cells. The role of V-ATPases in cancer and other human pathologies, and the prospects for therapeutic intervention, are also discussed.
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Affiliation(s)
- Michael P Collins
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America
| | - Michael Forgac
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America; Dept. of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, United States of America.
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43
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Abbas YM, Wu D, Bueler SA, Robinson CV, Rubinstein JL. Structure of V-ATPase from the mammalian brain. Science 2020; 367:1240-1246. [PMID: 32165585 DOI: 10.1126/science.aaz2924] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/12/2020] [Indexed: 12/16/2022]
Abstract
In neurons, the loading of neurotransmitters into synaptic vesicles uses energy from proton-pumping vesicular- or vacuolar-type adenosine triphosphatases (V-ATPases). These membrane protein complexes possess numerous subunit isoforms, which complicates their analysis. We isolated homogeneous rat brain V-ATPase through its interaction with SidK, a Legionella pneumophila effector protein. Cryo-electron microscopy allowed the construction of an atomic model, defining the enzyme's ATP:proton ratio as 3:10 and revealing a homolog of yeast subunit f in the membrane region, which we tentatively identify as RNAseK. The c ring encloses the transmembrane anchors for cleaved ATP6AP1/Ac45 and ATP6AP2/PRR, the latter of which is the (pro)renin receptor that, in other contexts, is involved in both Wnt signaling and the renin-angiotensin system that regulates blood pressure. This structure shows how ATP6AP1/Ac45 and ATP6AP2/PRR enable assembly of the enzyme's catalytic and membrane regions.
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Affiliation(s)
- Yazan M Abbas
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Di Wu
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada. .,Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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44
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Fassio A, Falace A, Esposito A, Aprile D, Guerrini R, Benfenati F. Emerging Role of the Autophagy/Lysosomal Degradative Pathway in Neurodevelopmental Disorders With Epilepsy. Front Cell Neurosci 2020; 14:39. [PMID: 32231521 PMCID: PMC7082311 DOI: 10.3389/fncel.2020.00039] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/10/2020] [Indexed: 01/08/2023] Open
Abstract
Autophagy is a highly conserved degradative process that conveys dysfunctional proteins, lipids, and organelles to lysosomes for degradation. The post-mitotic nature, complex and highly polarized morphology, and high degree of specialization of neurons make an efficient autophagy essential for their homeostasis and survival. Dysfunctional autophagy occurs in aging and neurodegenerative diseases, and autophagy at synaptic sites seems to play a crucial role in neurodegeneration. Moreover, a role of autophagy is emerging for neural development, synaptogenesis, and the establishment of a correct connectivity. Thus, it is not surprising that defective autophagy has been demonstrated in a spectrum of neurodevelopmental disorders, often associated with early-onset epilepsy. Here, we discuss the multiple roles of autophagy in neurons and the recent experimental evidence linking neurodevelopmental disorders with epilepsy to genes coding for autophagic/lysosomal system-related proteins and envisage possible pathophysiological mechanisms ranging from synaptic dysfunction to neuronal death.
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Affiliation(s)
- Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Alessandro Esposito
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.,IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
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45
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Vasanthakumar T, Rubinstein JL. Structure and Roles of V-type ATPases. Trends Biochem Sci 2020; 45:295-307. [PMID: 32001091 DOI: 10.1016/j.tibs.2019.12.007] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/05/2019] [Accepted: 12/31/2019] [Indexed: 12/19/2022]
Abstract
V-ATPases are membrane-embedded protein complexes that function as ATP hydrolysis-driven proton pumps. V-ATPases are the primary source of organellar acidification in all eukaryotes, making them essential for many fundamental cellular processes. Enzymatic activity can be modulated by regulated and reversible disassembly of the complex, and several subunits of mammalian V-ATPase have multiple isoforms that are differentially localized. Although the biochemical properties of the different isoforms are currently unknown, mutations in specific subunit isoforms have been associated with various diseases, making V-ATPases potential drug targets. V-ATPase structure and activity have been best characterized in Saccharomyces cerevisiae, where recent structures have revealed details about the dynamics of the enzyme, the proton translocation pathway, and conformational changes associated with regulated disassembly and autoinhibition.
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Affiliation(s)
- Thamiya Vasanthakumar
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - John L Rubinstein
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada.
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46
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Gowrisankaran S, Milosevic I. Regulation of synaptic vesicle acidification at the neuronal synapse. IUBMB Life 2020; 72:568-576. [DOI: 10.1002/iub.2235] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 12/29/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Sindhuja Gowrisankaran
- European Neuroscience Institute (ENI)A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen Germany
| | - Ira Milosevic
- European Neuroscience Institute (ENI)A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen Germany
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47
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Vásquez-Procopio J, Osorio B, Cortés-Martínez L, Hernández-Hernández F, Medina-Contreras O, Ríos-Castro E, Comjean A, Li F, Hu Y, Mohr S, Perrimon N, Missirlis F. Intestinal response to dietary manganese depletion inDrosophila. Metallomics 2020; 12:218-240. [DOI: 10.1039/c9mt00218a] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Metabolic adaptations to manganese deficiency.
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48
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Ma K, Bin NR, Shi S, Harada H, Wada Y, Wada GHS, Monnier PP, Sugita S, Zhang L. Observations From a Mouse Model of Forebrain Voa1 Knockout: Focus on Hippocampal Structure and Function. Front Cell Neurosci 2019; 13:484. [PMID: 31824264 PMCID: PMC6881385 DOI: 10.3389/fncel.2019.00484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 10/11/2019] [Indexed: 12/22/2022] Open
Abstract
Voa protein is a subunit of V-ATPase proton pump which is essential to acidify intracellular organelles including synaptic vesicles. Voa1 is one of the four isoforms of Voa family with strong expression in neurons. Our present study was aimed to examine the role of Voa1 protein in mammalian brain neurons. To circumvent embryonic lethality, we generated conditional Voa1 knockout mice in which Voa1 was selectively deleted from forebrain pyramidal neurons. We performed experiments in the Voa1 knockout mice of ages 5-6 months to assess the persistent effects of Voa1 deletion. We found that the Voa1 knockout mice exhibited poor performance in the Morris water maze test compared to control mice. In addition, synaptic field potentials of the hippocampal CA1 region were greatly diminished in the Voa1 knockout mice when examined in brain slices in vitro. Furthermore, brain histological experiments showed severe degeneration of dorsal hippocampal CA1 neurons while CA3 neurons were largely preserved. The CA1 neurodegeneration was associated with general brain atrophy as overall hemispheric areas were reduced in the Voa1 cKO mice. Despite the CA1 degeneration and dysfunction, electroencephalographic recordings from the hippocampal CA3 area revealed aberrant spikes and non-convulsive discharges in the Voa1 knockout mice but not in control mice. These hippocampal spikes were suppressed by single intra-peritoneal injection of diazepam which is a benzodiazepine GABAA receptor enhancer. Together these results suggest that Voa1 related activities are essential for the survival of the targeted neurons in the dorsal hippocampal CA1 as well as other forebrain areas. We postulate that the Voa1 knockout mice may serve as a valuable model for further investigation of V-ATPase dysfunction related neuronal degeneration and functional abnormalities in forebrain areas particularly the hippocampus.
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Affiliation(s)
- Ke Ma
- Department of Pediatric Outpatient, The First Hospital of Jilin University, Jilin, China.,Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Na-Ryum Bin
- Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Shan Shi
- Department of Pediatric Outpatient, The First Hospital of Jilin University, Jilin, China.,Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Hidekiyo Harada
- Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Yoh Wada
- Division of Biological Science, Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Ge-Hong-Sun Wada
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College, Kyoto, Japan
| | - Philippe P Monnier
- Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Ophthalmology, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Shuzo Sugita
- Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Liang Zhang
- Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada
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49
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Cashikar AG, Hanson PI. A cell-based assay for CD63-containing extracellular vesicles. PLoS One 2019; 14:e0220007. [PMID: 31339911 PMCID: PMC6655660 DOI: 10.1371/journal.pone.0220007] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 07/05/2019] [Indexed: 02/06/2023] Open
Abstract
Extracellular vesicles (EVs) are thought to be important in cell-cell communication and have elicited extraordinary interest as potential biomarkers of disease. However, quantitative methods to enable elucidation of mechanisms underlying release are few. Here, we describe a cell-based assay for monitoring EV release using the EV-enriched tetraspanin CD63 fused to the small, ATP-independent reporter enzyme, Nanoluciferase. Release of CD63-containing EVs from stably expressing cell lines was monitored by comparing luciferase activity in culture media to that remaining in cells. HEK293, U2OS, U87 and SKMel28 cells released 0.3%-0.6% of total cellular CD63 in the form of EVs over 5 hrs, varying by cell line. To identify cellular machinery important for secretion of CD63-containing EVs, we performed a screen of biologically active chemicals in HEK293 cells. While a majority of compounds did not significantly affect EV release, treating cells with the plecomacrolides bafilomycin or concanamycin, known to inhibit the V-ATPase, dramatically increased EV release. Interestingly, alkalization of the endosomal lumen using weak bases had no effect, suggesting a pH-independent enhancement of EV release by V-ATPase inhibitors. The ability to quantify EVs in small samples will enable future detailed studies of release kinetics as well as further chemical and genetic screening to define pathways involved in EV secretion.
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Affiliation(s)
- Anil G. Cashikar
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Phyllis I. Hanson
- Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
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50
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Fassio A, Esposito A, Kato M, Saitsu H, Mei D, Marini C, Conti V, Nakashima M, Okamoto N, Olmez Turker A, Albuz B, Semerci Gündüz CN, Yanagihara K, Belmonte E, Maragliano L, Ramsey K, Balak C, Siniard A, Narayanan V, Ohba C, Shiina M, Ogata K, Matsumoto N, Benfenati F, Guerrini R. De novo mutations of the ATP6V1A gene cause developmental encephalopathy with epilepsy. Brain 2019; 141:1703-1718. [PMID: 29668857 PMCID: PMC5972584 DOI: 10.1093/brain/awy092] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 02/10/2018] [Indexed: 12/30/2022] Open
Abstract
V-type proton (H+) ATPase (v-ATPase) is a multi-subunit proton pump that regulates pH homeostasis in all eukaryotic cells; in neurons, v-ATPase plays additional and unique roles in synapse function. Through whole exome sequencing, we identified de novo heterozygous mutations (p.Pro27Arg, p.Asp100Tyr, p.Asp349Asn, p.Asp371Gly) in ATP6V1A, encoding the A subunit of v-ATPase, in four patients with developmental encephalopathy with epilepsy. Early manifestations, observed in all patients, were developmental delay and febrile seizures, evolving to encephalopathy with profound delay, hypotonic/dyskinetic quadriparesis and intractable multiple seizure types in two patients (p.Pro27Arg, p.Asp100Tyr), and to moderate delay with milder epilepsy in the other two (p.Asp349Asn, p.Asp371Gly). Modelling performed on the available prokaryotic and eukaryotic structures of v-ATPase predicted p.Pro27Arg to perturb subunit interaction, p.Asp100Tyr to cause steric hindrance and destabilize protein folding, p.Asp349Asn to affect the catalytic function and p.Asp371Gly to impair the rotation process, necessary for proton transport. We addressed the impact of p.Asp349Asn and p.Asp100Tyr mutations on ATP6V1A expression and function by analysing ATP6V1A-overexpressing HEK293T cells and patients’ lymphoblasts. The p.Asp100Tyr mutant was characterized by reduced expression due to increased degradation. Conversely, no decrease in expression and clearance was observed for p.Asp349Asn. In HEK293T cells overexpressing either pathogenic or control variants, p.Asp349Asn significantly increased LysoTracker® fluorescence with no effects on EEA1 and LAMP1 expression. Conversely, p.Asp100Tyr decreased both LysoTracker® fluorescence and LAMP1 levels, leaving EEA1 expression unaffected. Both mutations decreased v-ATPase recruitment to autophagosomes, with no major impact on autophagy. Experiments performed on patients’ lymphoblasts using the LysoSensor™ probe revealed lower pH of endocytic organelles for p.Asp349Asn and a reduced expression of LAMP1 with no effect on the pH for p.Asp100Tyr. These data demonstrate gain of function for p.Asp349Asn characterized by an increased proton pumping in intracellular organelles, and loss of function for p.Asp100Tyr with decreased expression of ATP6V1A and reduced levels of lysosomal markers. We expressed p.Asp349Asn and p.Asp100Tyr in rat hippocampal neurons and confirmed significant and opposite effects in lysosomal labelling. However, both mutations caused a similar defect in neurite elongation accompanied by loss of excitatory inputs, revealing that altered lysosomal homeostasis markedly affects neurite development and synaptic connectivity. This study provides evidence that de novo heterozygous ATP6V1A mutations cause a developmental encephalopathy with a pathomechanism that involves perturbations of lysosomal homeostasis and neuronal connectivity, uncovering a novel role for v-ATPase in neuronal development.
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Affiliation(s)
- Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Alessandro Esposito
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Mitsuhiro Kato
- Department of Paediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Davide Mei
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Carla Marini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Valerio Conti
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Mitsuko Nakashima
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan.,Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Osaka, Japan
| | | | - Burcu Albuz
- Department of Medical Genetics, Pamukkale University Hospital, Denizli, Turkey
| | | | - Keiko Yanagihara
- Department of Paediatric Neurology, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Elisa Belmonte
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Luca Maragliano
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Keri Ramsey
- Center for Rare Childhood Disorders and Neurogenomics Division Translational Genomics Research Institute, Phoenix, Arizona 85004, USA
| | - Chris Balak
- Center for Rare Childhood Disorders and Neurogenomics Division Translational Genomics Research Institute, Phoenix, Arizona 85004, USA
| | - Ashley Siniard
- Center for Rare Childhood Disorders and Neurogenomics Division Translational Genomics Research Institute, Phoenix, Arizona 85004, USA
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders and Neurogenomics Division Translational Genomics Research Institute, Phoenix, Arizona 85004, USA
| | | | - Chihiro Ohba
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Masaaki Shiina
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Kazuhiro Ogata
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Fabio Benfenati
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.,IRCCS Fondazione Stella Maris, Pisa, Italy
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