1
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Wu JJ, Yu H, Bi SG, Wang ZX, Gong J, Mao YM, Wang FZ, Zhang YQ, Nie YJ, Chai GS. Aerobic exercise attenuates autophagy-lysosomal flux deficits by ADRB2/β2-adrenergic receptor-mediated V-ATPase assembly factor VMA21 signaling in APP-PSEN1/PS1 mice. Autophagy 2024; 20:1015-1031. [PMID: 37964627 PMCID: PMC11135842 DOI: 10.1080/15548627.2023.2281134] [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: 05/23/2023] [Accepted: 11/03/2023] [Indexed: 11/16/2023] Open
Abstract
Growing evidence suggests that macroautophagy/autophagy-lysosomal pathway deficits contribute to the accumulation of amyloid-β (Aβ) in Alzheimer disease (AD). Aerobic exercise (AE) has long been investigated as an approach to delay and treat AD, although the exact role and mechanism are not well known. Here, we revealed that AE could reverse autophagy-lysosomal deficits via activation of ADRB2/β2-adrenergic receptor, leading to significant attenuation of amyloid-β pathology in APP-PSEN1/PS1 mice. Molecular mechanism research found that AE could reverse autophagy deficits by upregulating the AMP-activated protein kinase (AMPK)-MTOR (mechanistic target of rapamycin kinase) signaling pathway. Moreover, AE could reverse V-ATPase function by upregulating VMA21 levels. Inhibition of ADRB2 by propranolol (antagonist, 30 μM) blocked AE-attenuated Aβ pathology and cognitive deficits by inhibiting autophagy-lysosomal flux. AE may mitigate AD via many pathways, while ADRB2-VMA21-V-ATPase could improve cognition by enhancing the clearance of Aβ through the autophagy-lysosomal pathway, which also revealed a novel theoretical basis for AE attenuating pathological progression and cognitive deficits in AD.
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Affiliation(s)
- Jia-Jun Wu
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
- Department of electrophysiology, Wuhan Children’s Hospital (Wuhan Maternal and Children’s Healthcare Center), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Haitao Yu
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Shu-Guang Bi
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Zhong-Xuan Wang
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Juan Gong
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Yu-Ming Mao
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Fang-Zhou Wang
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Yu-Qi Zhang
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Yun-Juan Nie
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Gao-Shang Chai
- Department of Fundamental Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
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2
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Cocchiararo I, Cattaneo O, Rajendran J, Chabry F, Cornut M, Soldati H, Bigot A, Mamchaoui K, Gibertini S, Bouche A, Ham DJ, Laumonier T, Prola A, Castets P. Identification of a muscle-specific isoform of VMA21 as a potent actor in X-linked myopathy with excessive autophagy pathogenesis. Hum Mol Genet 2023; 32:3374-3389. [PMID: 37756622 PMCID: PMC10695681 DOI: 10.1093/hmg/ddad164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/23/2023] [Accepted: 09/21/2023] [Indexed: 09/29/2023] Open
Abstract
Defective lysosomal acidification is responsible for a large range of multi-systemic disorders associated with impaired autophagy. Diseases caused by mutations in the VMA21 gene stand as exceptions, specifically affecting skeletal muscle (X-linked Myopathy with Excessive Autophagy, XMEA) or liver (Congenital Disorder of Glycosylation). VMA21 chaperones vacuolar (v-) ATPase assembly, which is ubiquitously required for proper lysosomal acidification. The reason VMA21 deficiencies affect specific, but divergent tissues remains unknown. Here, we show that VMA21 encodes a yet-unreported long protein isoform, in addition to the previously described short isoform, which we name VMA21-120 and VMA21-101, respectively. In contrast to the ubiquitous pattern of VMA21-101, VMA21-120 was predominantly expressed in skeletal muscle, and rapidly up-regulated upon differentiation of mouse and human muscle precursors. Accordingly, VMA21-120 accumulated during development, regeneration and denervation of mouse skeletal muscle. In contrast, neither induction nor blockade of autophagy, in vitro and in vivo, strongly affected VMA21 isoform expression. Interestingly, VMA21-101 and VMA21-120 both localized to the sarcoplasmic reticulum of muscle cells, and interacted with the v-ATPase. While VMA21 deficiency impairs autophagy, VMA21-101 or VMA21-120 overexpression had limited impact on autophagic flux in muscle cells. Importantly, XMEA-associated mutations lead to both VMA21-101 deficiency and loss of VMA21-120 expression. These results provide important insights into the clinical diversity of VMA21-related diseases and uncover a muscle-specific VMA21 isoform that potently contributes to XMEA pathogenesis.
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Affiliation(s)
- Ilaria Cocchiararo
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Olivia Cattaneo
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Jayasimman Rajendran
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Florent Chabry
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Mélanie Cornut
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Hadrien Soldati
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Anne Bigot
- Centre de Recherche en Myologie, Inserm, Institut de Myologie, Sorbonne Université, 47 Bd de l'Hôpital, 75013 Paris, France
| | - Kamel Mamchaoui
- Centre de Recherche en Myologie, Inserm, Institut de Myologie, Sorbonne Université, 47 Bd de l'Hôpital, 75013 Paris, France
| | - Sara Gibertini
- Neuromuscular Diseases and Neuroimmunology Unit, Muscle Cell Biology Lab, Fondazione IRCCS Istituto Neurologico “C. Besta”, Via Amadeo 42, 20133 Milano, Italy
| | - Axelle Bouche
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
- Department of Orthopaedic Surgery, Geneva University Hospitals and Faculty of Medicine, University Medical Center, 1 rue Michel Servet, 1211, Geneva, Switzerland
| | - Daniel J Ham
- Biozentrum, University of Basel, Spitalstrasse 41, 4056 Basel, Switzerland
| | - Thomas Laumonier
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
- Department of Orthopaedic Surgery, Geneva University Hospitals and Faculty of Medicine, University Medical Center, 1 rue Michel Servet, 1211, Geneva, Switzerland
| | - Alexandre Prola
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
| | - Perrine Castets
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, CH-1211 Geneva, Switzerland
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3
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Fabri LM, Garçon DP, Moraes CM, Pinto MR, McNamara JC, Leone FA. A kinetic characterization of the gill V(H +)-ATPase from two hololimnetic populations of the Amazon River shrimp Macrobrachium amazonicum. Comp Biochem Physiol B Biochem Mol Biol 2023; 268:110880. [PMID: 37517460 DOI: 10.1016/j.cbpb.2023.110880] [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: 05/08/2023] [Revised: 07/27/2023] [Accepted: 07/27/2023] [Indexed: 08/01/2023]
Abstract
This investigation examines the kinetic characteristics and effect of acclimation to a brackish medium (21 ‰S) on gill V(H+)-ATPase activity in two hololimnetic populations of M. amazonicum. We also investigate the cellular immunolocalization of the enzyme. Immunofluorescence findings demonstrate that the V(H+)-ATPase c-subunit is distributed in the apical pillar cells of shrimps in fresh water but is absent after acclimation to 21 ‰S for 10 days. V(H+)-ATPase activity from the Tietê River population is ≈50% greater than the Grande River population, comparable to a wild population from the Santa Elisa Reservoir, but is 2-fold less than in cultivated shrimps. V(H+)-ATPase activity in the Tietê and the Grande River shrimps is abolished after 21 ‰S acclimation. The apparent affinities of the V(H+)-ATPase for ATP (0.27 ± 0.04 and 0.16 ± 0.03 mmol L-1, respectively) and Mg2+ (0.28 ± 0.05 and 0.14 ± 0.02 mmol L-1, respectively) are similar in both populations. The absence of V(H+)-ATPase activity in salinity-acclimated shrimps and its apical distribution in shrimps in fresh water underpins the importance of the crustacean V(H+)-ATPase for ion uptake in fresh water.
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Affiliation(s)
- Leonardo M Fabri
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Brazil
| | - Daniela P Garçon
- Universidade Federal do Triângulo Mineiro, Campus Universitário de Iturama, 38280-000, Brazil
| | - Cintya M Moraes
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Brazil
| | - Marcelo R Pinto
- Laboratory of Biopathology and Molecular Biology, University of Uberaba, Uberaba, Minas Gerais, Brazil
| | - John C McNamara
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil.; Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, 11000-600, Brazil. https://twitter.com/maracoani
| | - Francisco A Leone
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil.
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4
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Sankaranarayanan S, Haag C, Petzsch P, Köhrer K, Matuszyńska A, Zarnack K, Feldbrügge M. The mRNA stability factor Khd4 defines a specific mRNA regulon for membrane trafficking in the pathogen Ustilago maydis. Proc Natl Acad Sci U S A 2023; 120:e2301731120. [PMID: 37590419 PMCID: PMC10450656 DOI: 10.1073/pnas.2301731120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 07/10/2023] [Indexed: 08/19/2023] Open
Abstract
Fungal pathogens depend on sophisticated gene expression programs for successful infection. A crucial component is RNA regulation mediated by RNA-binding proteins (RBPs). However, little is known about the spatiotemporal RNA control mechanisms during fungal pathogenicity. Here, we discover that the RBP Khd4 defines a distinct mRNA regulon to orchestrate membrane trafficking during pathogenic development of Ustilago maydis. By establishing hyperTRIBE for fungal RBPs, we generated a comprehensive transcriptome-wide map of Khd4 interactions in vivo. We identify a defined set of target mRNAs enriched for regulatory proteins involved, e.g., in GTPase signaling. Khd4 controls the stability of target mRNAs via its cognate regulatory element AUACCC present in their 3' untranslated regions. Studying individual examples reveals a unique link between Khd4 and vacuole maturation. Thus, we uncover a distinct role for an RNA stability factor defining a specific mRNA regulon for membrane trafficking during pathogenicity.
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Affiliation(s)
- Srimeenakshi Sankaranarayanan
- Institute of Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, Düsseldorf40204, Germany
| | - Carl Haag
- Institute of Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, Düsseldorf40204, Germany
| | - Patrick Petzsch
- Biologisch-Medizinisches Forschungszentrum, Heinrich Heine University Düsseldorf, Düsseldorf40204, Germany
| | - Karl Köhrer
- Biologisch-Medizinisches Forschungszentrum, Heinrich Heine University Düsseldorf, Düsseldorf40204, Germany
| | - Anna Matuszyńska
- Department of Biology, Computational Life Science, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen52074, Germany
| | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt a.M.60438, Germany
- Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt a.M.60438, Germany
| | - Michael Feldbrügge
- Institute of Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, Düsseldorf40204, Germany
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5
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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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6
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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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7
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Structural basis of V-ATPase V O region assembly by Vma12p, 21p, and 22p. Proc Natl Acad Sci U S A 2023; 120:e2217181120. [PMID: 36724250 PMCID: PMC9963935 DOI: 10.1073/pnas.2217181120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Vacuolar-type adenosine triphosphatases (V-ATPases) are rotary proton pumps that acidify specific intracellular compartments in almost all eukaryotic cells. These multi-subunit enzymes consist of a soluble catalytic V1 region and a membrane-embedded proton-translocating VO region. VO is assembled in the endoplasmic reticulum (ER) membrane, and V1 is assembled in the cytosol. However, V1 binds VO only after VO is transported to the Golgi membrane, thereby preventing acidification of the ER. We isolated VO complexes and subcomplexes from Saccharomyces cerevisiae bound to V-ATPase assembly factors Vma12p, Vma21p, and Vma22p. Electron cryomicroscopy shows how the Vma12-22p complex recruits subunits a, e, and f to the rotor ring of VO while blocking premature binding of V1. Vma21p, which contains an ER-retrieval motif, binds the VO:Vma12-22p complex, "mature" VO, and a complex that appears to contain a ring of loosely packed rotor subunits and the proteins YAR027W and YAR028W. The structures suggest that Vma21p binds assembly intermediates that contain a rotor ring and that activation of proton pumping following assembly of V1 with VO removes Vma21p, allowing V-ATPase to remain in the Golgi. Together, these structures show how Vma12-22p and Vma21p function in V-ATPase assembly and quality control, ensuring the enzyme acidifies only its intended cellular targets.
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8
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Wang F, Yang Y, Klionsky DJ, Malek SN. Mutations in V-ATPase in follicular lymphoma activate autophagic flux creating a targetable dependency. Autophagy 2023; 19:716-719. [PMID: 35482846 PMCID: PMC9851240 DOI: 10.1080/15548627.2022.2071382] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 04/25/2022] [Accepted: 04/25/2022] [Indexed: 01/22/2023] Open
Abstract
The recent discovery of recurrent gene mutations in chaperones or components of the vacuolar-type H+-translocating ATPase (V-ATPase) in follicular lymphoma (FL) was an unexpected finding. The application of whole exome sequencing and targeted gene re-sequencing has resulted in the identification of mutations in ATP6AP1, ATP6V1B2 and VMA21 in a combined 30% of FL, together constituting a major novel mutated pathway in this disease. Interestingly, no other human hematological malignancy carries these mutations at more than sporadic occurrences, implicating unique aspects of FL biology requiring these mutations. The mutations in ATP6V1B2 and VMA21 through separate mechanisms impair lysosomal V-ATPase activity resulting in an elevated lysosomal pH. The elevated lysosomal pH impairs protein and peptide hydrolysis and associates with reduced cytoplasmic amino acid concentrations resulting in compensatory activation of autophagic flux. The elevated autophagic flux constitutes a survival dependency for FL cells and can be targeted with inhibitors to ULK1 and multiple recently identified cyclin-dependent kinase inhibitors. Targeting autophagy alone or in combination with other targeted therapies constitutes a novel therapeutic opportunity for FL patients.
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Affiliation(s)
- Fangyang Wang
- Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Ying Yang
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Daniel J. Klionsky
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Sami N. Malek
- Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
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9
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Wang F, Yang Y, Boudagh G, Eskelinen EL, Klionsky DJ, Malek SN. Follicular lymphoma-associated mutations in the V-ATPase chaperone VMA21 activate autophagy creating a targetable dependency. Autophagy 2022; 18:1982-2000. [PMID: 35287545 PMCID: PMC9450968 DOI: 10.1080/15548627.2022.2050663] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
The discovery of recurrent mutations in subunits and regulators of the vacuolar-type H+-translocating ATPase (V-ATPase) in follicular lymphoma (FL) highlights a role for macroautophagy/autophagy, amino-acid, and nutrient-sensing pathways in the pathogenesis of this disease. Here, we report on novel mutations in the ER-resident chaperone VMA21, which is involved in V-ATPase assembly in 12% of FL. Mutations in a novel VMA21 hotspot (p.93X) result in the removal of a C-terminal non-canonical ER retrieval signal thus causing VMA21 mislocalization to lysosomes. The resulting impairment in V-ATPase activity prevents full lysosomal acidification and function, including impaired pH-dependent protein degradation as shown via lysosomal metabolomics and ultimately causes a degree of amino acid depletion in the cytoplasm. These deficiencies result in compensatory autophagy activation, as measured using multiple complementary assays in human and yeast cells. Of translational significance, the compensatory activation of autophagy creates a dependency for survival for VMA21-mutated primary human FL as shown using inhibitors to ULK1, the proximal autophagy-regulating kinase. Using high-throughput microscopy-based screening assays for autophagy-inhibiting compounds, we identify multiple clinical grade cyclin-dependent kinase inhibitors as promising drugs and thus provide new rationale for innovative clinical trials in FL harboring aberrant V-ATPase.Abbreviations: ALs: autolysosomes; APs: autophagosomes; ER: endoplasmic reticulum; FL: follicular lymphoma; GFP: green fluorescent protein; IP: immunoprecipitation; LE/LY: late endosomes/lysosomes; Lyso-IP: lysosomal immunoprecipitation; OST: oligosaccharide transferase; prApe1: precursor aminopeptidase I; SEP: super ecliptic pHluorin; V-ATPase: vacuolar-type H+-translocating ATPase.
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Affiliation(s)
- Fangyang Wang
- Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Ying Yang
- Departments of Molecular, Cellular and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Gabriel Boudagh
- Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
| | | | - Daniel J. Klionsky
- Departments of Molecular, Cellular and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Sami N. Malek
- Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
- CONTACT Sami N. Malek Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, MI48109-0936, USA
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10
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Seidel T. The Plant V-ATPase. FRONTIERS IN PLANT SCIENCE 2022; 13:931777. [PMID: 35845650 PMCID: PMC9280200 DOI: 10.3389/fpls.2022.931777] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/03/2022] [Indexed: 05/25/2023]
Abstract
V-ATPase is the dominant proton pump in plant cells. It contributes to cytosolic pH homeostasis and energizes transport processes across endomembranes of the secretory pathway. Its localization in the trans Golgi network/early endosomes is essential for vesicle transport, for instance for the delivery of cell wall components. Furthermore, it is crucial for response to abiotic and biotic stresses. The V-ATPase's rather complex structure and multiple subunit isoforms enable high structural flexibility with respect to requirements for different organs, developmental stages, and organelles. This complexity further demands a sophisticated assembly machinery and transport routes in cells, a process that is still not fully understood. Regulation of V-ATPase is a target of phosphorylation and redox-modifications but also involves interactions with regulatory proteins like 14-3-3 proteins and the lipid environment. Regulation by reversible assembly, as reported for yeast and the mammalian enzyme, has not be proven in plants but seems to be absent in autotrophic cells. Addressing the regulation of V-ATPase is a promising approach to adjust its activity for improved stress resistance or higher crop yield.
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11
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Gutiérrez-Pérez P, Santillán EM, Lendl T, Wang J, Schrempf A, Steinacker TL, Asparuhova M, Brandstetter M, Haselbach D, Cochella L. miR-1 sustains muscle physiology by controlling V-ATPase complex assembly. SCIENCE ADVANCES 2021; 7:eabh1434. [PMID: 34652942 PMCID: PMC8519577 DOI: 10.1126/sciadv.abh1434] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 08/23/2021] [Indexed: 05/13/2023]
Abstract
Muscle function requires unique structural and metabolic adaptations that can render muscle cells selectively vulnerable, with mutations in some ubiquitously expressed genes causing myopathies but sparing other tissues. We uncovered a muscle cell vulnerability by studying miR-1, a deeply conserved, muscle-specific microRNA whose ablation causes various muscle defects. Using Caenorhabditis elegans, we found that miR-1 represses multiple subunits of the ubiquitous vacuolar adenosine triphosphatase (V-ATPase) complex, which is essential for internal compartment acidification and metabolic signaling. V-ATPase subunits are predicted miR-1 targets in animals ranging from C. elegans to humans, and we experimentally validated this in Drosophila. Unexpectedly, up-regulation of V-ATPase subunits upon miR-1 deletion causes reduced V-ATPase function due to defects in complex assembly. These results reveal V-ATPase assembly as a conserved muscle cell vulnerability and support a previously unknown role for microRNAs in the regulation of protein complexes.
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Affiliation(s)
- Paula Gutiérrez-Pérez
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030 Vienna, Austria
| | - Emilio M. Santillán
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030 Vienna, Austria
| | - Thomas Lendl
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Jingkui Wang
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Anna Schrempf
- Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | | | - Mila Asparuhova
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Marlene Brandstetter
- Electron Microscopy Facility, Vienna BioCenter Core Facilities GmbH, Vienna, Austria
| | - David Haselbach
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Luisa Cochella
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
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12
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Xia Q, Huang X, Huang J, Zheng Y, March ME, Li J, Wei Y. The Role of Autophagy in Skeletal Muscle Diseases. Front Physiol 2021; 12:638983. [PMID: 33841177 PMCID: PMC8027491 DOI: 10.3389/fphys.2021.638983] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/22/2021] [Indexed: 12/13/2022] Open
Abstract
Skeletal muscle is the most abundant type of tissue in human body, being involved in diverse activities and maintaining a finely tuned metabolic balance. Autophagy, characterized by the autophagosome–lysosome system with the involvement of evolutionarily conserved autophagy-related genes, is an important catabolic process and plays an essential role in energy generation and consumption, as well as substance turnover processes in skeletal muscles. Autophagy in skeletal muscles is finely tuned under the tight regulation of diverse signaling pathways, and the autophagy pathway has cross-talk with other pathways to form feedback loops under physiological conditions and metabolic stress. Altered autophagy activity characterized by either increased formation of autophagosomes or inhibition of lysosome-autophagosome fusion can lead to pathological cascades, and mutations in autophagy genes and deregulation of autophagy pathways have been identified as one of the major causes for a variety of skeleton muscle disorders. The advancement of multi-omics techniques enables further understanding of the molecular and biochemical mechanisms underlying the role of autophagy in skeletal muscle disorders, which may yield novel therapeutic targets for these disorders.
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Affiliation(s)
- Qianghua Xia
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
| | - Xubo Huang
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
| | - Jieru Huang
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
| | - Yongfeng Zheng
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
| | - Michael E March
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Jin Li
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
| | - Yongjie Wei
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
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13
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Cannata Serio M, Graham LA, Ashikov A, Larsen LE, Raymond K, Timal S, Le Meur G, Ryan M, Czarnowska E, Jansen JC, He M, Ficicioglu C, Pichurin P, Hasadsri L, Minassian B, Rugierri A, Kalimo H, Ríos‐Ocampo WA, Gilissen C, Rodenburg R, Jonker JW, Holleboom AG, Morava E, Veltman JA, Socha P, Stevens TH, Simons M, Lefeber DJ. Mutations in the V-ATPase Assembly Factor VMA21 Cause a Congenital Disorder of Glycosylation With Autophagic Liver Disease. Hepatology 2020; 72:1968-1986. [PMID: 32145091 PMCID: PMC7483274 DOI: 10.1002/hep.31218] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 02/14/2020] [Accepted: 02/14/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIMS Vacuolar H+-ATP complex (V-ATPase) is a multisubunit protein complex required for acidification of intracellular compartments. At least five different factors are known to be essential for its assembly in the endoplasmic reticulum (ER). Genetic defects in four of these V-ATPase assembly factors show overlapping clinical features, including steatotic liver disease and mild hypercholesterolemia. An exception is the assembly factor vacuolar ATPase assembly integral membrane protein (VMA21), whose X-linked mutations lead to autophagic myopathy. APPROACH AND RESULTS Here, we report pathogenic variants in VMA21 in male patients with abnormal protein glycosylation that result in mild cholestasis, chronic elevation of aminotransferases, elevation of (low-density lipoprotein) cholesterol and steatosis in hepatocytes. We also show that the VMA21 variants lead to V-ATPase misassembly and dysfunction. As a consequence, lysosomal acidification and degradation of phagocytosed materials are impaired, causing lipid droplet (LD) accumulation in autolysosomes. Moreover, VMA21 deficiency triggers ER stress and sequestration of unesterified cholesterol in lysosomes, thereby activating the sterol response element-binding protein-mediated cholesterol synthesis pathways. CONCLUSIONS Together, our data suggest that impaired lipophagy, ER stress, and increased cholesterol synthesis lead to LD accumulation and hepatic steatosis. V-ATPase assembly defects are thus a form of hereditary liver disease with implications for the pathogenesis of nonalcoholic fatty liver disease.
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Affiliation(s)
- Magda Cannata Serio
- Laboratory of Epithelial Biology and DiseaseImagine InstituteUniversité Paris Descartes‐Sorbonne Paris CitéParisFrance,RBIV RNA Biology of Influenza Viruses UnitInstitut PasteurCNRS, UMR3569ParisFrance
| | - Laurie A. Graham
- Department of Chemistry and BiochemistryInstitute of Molecular BiologyUniversity of OregonEugeneOR
| | - Angel Ashikov
- Department of NeurologyDonders Institute for BrainCognition and BehaviourRadboud University Medical CenterNijmegenthe Netherlands,Department of Laboratory MedicineTranslational Metabolic LaboratoryRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenthe Netherlands
| | - Lars Elmann Larsen
- Department of Laboratory Medicine and PathologyMayo College of MedicineRochesterMN,Department of Chemistry and BiochemistryInstitute of Molecular BiologyUniversity of OregonEugeneOR
| | - Kimiyo Raymond
- Department of PathologyThe Children’s Memorial Health InstituteWarsawPoland
| | - Sharita Timal
- Department of NeurologyDonders Institute for BrainCognition and BehaviourRadboud University Medical CenterNijmegenthe Netherlands,Department of Laboratory MedicineTranslational Metabolic LaboratoryRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenthe Netherlands
| | - Gwenn Le Meur
- Laboratory of Epithelial Biology and DiseaseImagine InstituteUniversité Paris Descartes‐Sorbonne Paris CitéParisFrance
| | - Margret Ryan
- Department of Gastroenterology and HepatologyTranslational Metabolic LaboratoryRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenthe Netherlands
| | - Elzbieta Czarnowska
- Department of Pathology and Laboratory MedicineUniversity of PennsylvaniaPerelman School of MedicinePhiladelphiaPA
| | - Jos C. Jansen
- Division of Laboratory MedicineThe Children’s Hospital of PhiladelphiaPhiladelphiaPA
| | - Miao He
- Division of Human GeneticsDepartment of PediatricsThe Children’s Hospital of PhiladelphiaPhiladelphiaPA,Department of Clinical GenomicsCollege of MedicineMayo ClinicRochesterMN
| | - Can Ficicioglu
- Division of Laboratory GeneticsDepartment of Laboratory Medicine and PathologyMayo ClinicRochesterMN
| | - Pavel Pichurin
- Department of Human GeneticsRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenthe Netherlands
| | - Linda Hasadsri
- Department of PediatricsRadboudumc Amalia Childrens HospitalRadboud Center for Mitochondrial MedicineNijmegenthe Netherlands
| | - Berge Minassian
- Department of PediatricsUniversity of Texas SouthwesternDallasTXUSA
| | - Alessandra Rugierri
- Department of Neuroimmunology and Neuromuscular DiseasesFondazione IRCCS Neurological Institute Carlo BestaMilanItaly,Department of Molecular and Translation MedicineUnit of Biology and Genetics, University of BresciaBresciaItaly
| | - Hannu Kalimo
- Department of Pathology, Haartman InstituteUniversity of Helsinki, FIN–00014HelsinkiFinland
| | | | | | - Richard Rodenburg
- Department of Human GeneticsDonders Centre for NeuroscienceRadboud University Medical CenterNijmegenthe Netherlands
| | - Johan W. Jonker
- Department of Laboratory Medicine and PathologyMayo College of MedicineRochesterMN
| | - Adriaan G. Holleboom
- Department of Chemistry and BiochemistryInstitute of Molecular BiologyUniversity of OregonEugeneOR
| | - Eva Morava
- Institute of Genetic MedicineInternational Centre for LifeNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Joris A. Veltman
- Department of GastroenterologyFeeding Disorders and PediatricsChildren’s Memorial Health InstituteWarsawPoland,Section of Molecular Metabolism and NutritionDepartment of PediatricsUniversity of GroningenUniversity Medical Center GroningenGroningenthe Netherlands
| | - Piotr Socha
- Department of Experimental Vascular MedicineAmsterdam University Medical CentersLocation AMCAmsterdamthe Netherlands
| | - Tom H. Stevens
- Department of Gastroenterology and HepatologyTranslational Metabolic LaboratoryRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenthe Netherlands
| | - Matias Simons
- Laboratory of Epithelial Biology and DiseaseImagine InstituteUniversité Paris Descartes‐Sorbonne Paris CitéParisFrance,Institute of Human GeneticsUniversity Hospital HeidelbergHeidelbergGermany
| | - Dirk J. Lefeber
- Department of NeurologyDonders Institute for BrainCognition and BehaviourRadboud University Medical CenterNijmegenthe Netherlands,Department of Laboratory MedicineTranslational Metabolic LaboratoryRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenthe Netherlands
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14
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Malik U, Zafar S, Younas N, Zerr I, Javed A. Unveiling the Physical and Functional Niches of FAM26F by Analyzing Its Subcellular Localization and Novel Interacting Partners. ACS OMEGA 2020; 5:22008-22020. [PMID: 32923759 PMCID: PMC7482079 DOI: 10.1021/acsomega.0c01249] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
The knowledge of a protein's subcellular localization and interacting partners are crucial for elucidating its cellular function and associated regulatory networks. Although FAM26F (family with sequence similarity 26, member F) has been recognized as a vital player in various infections, stimulation studies, cancer, and immune pathogenesis, the precise location and function of FAM26F are not well understood. The current study is the first to focus on functional characterization of FAM26F by analyzing its subcellular localization and identifying its novel interacting partners using advanced proteome approaches. The immunofluorescence and confocal microscopy results revealed FAM26F to be largely localized within the Golgi apparatus of the cell. However, its minor presence in endoplasmic reticulum (ER) pointed toward the probable retrograde transfer of FAM26F from Golgi to ER during adverse conditions. Moreover, co-immunoprecipitation and MS/MS results demonstrated a total of 85 proteins, 44 of which significantly copurified with FAM26F. Interestingly, out of these 44 MS/MS identified proteins, almost 52% were involved in innate immunity, 38.6% in neutrophil degranulation, and remaining 10% were either involved in phosphorylation, degradation, or regulation of apoptosis. Further characterization through Ingenuity Pathway Analysis showed that majority of these proteins was involved in maintaining calcium homeostasis of cell. Consequently, the validation of selected proteins uncovered the key interaction of FAM26F with Thioredoxin, which essentially paved the way for depicting its mechanism of action under stress or disease conditions. It is proposed that activation and inhibition of the cellular immune response is essentially dependent on whether FAM26F or Thioredoxin considerably interact with CD30R.
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Affiliation(s)
- Uzma Malik
- Department
of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences
(ASAB), National University of Sciences
and Technology (NUST), H-12 Campus, 44000 Islamabad, Pakistan
- Department
of Neurology, University Medical Centre Göttingen (UMG), Georg-August-Universität Göttingen, 37075 Göttingen, Germany
| | - Saima Zafar
- Department
of Neurology, University Medical Centre Göttingen (UMG), Georg-August-Universität Göttingen, 37075 Göttingen, Germany
- Department
of Biomedical Engineering & Sciences, School of Mechanical &
Manufacturing Engineering (SMME), National
University of Sciences and Technology (NUST), H-12
Campus, 44000 Islamabad, Pakistan
| | - Neelam Younas
- Department
of Neurology, University Medical Centre Göttingen (UMG), Georg-August-Universität Göttingen, 37075 Göttingen, Germany
| | - Inga Zerr
- Department
of Neurology, University Medical Centre Göttingen (UMG), Georg-August-Universität Göttingen, 37075 Göttingen, Germany
| | - Aneela Javed
- Department
of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences
(ASAB), National University of Sciences
and Technology (NUST), H-12 Campus, 44000 Islamabad, Pakistan
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15
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Linders PTA, Peters E, ter Beest M, Lefeber DJ, van den Bogaart G. Sugary Logistics Gone Wrong: Membrane Trafficking and Congenital Disorders of Glycosylation. Int J Mol Sci 2020; 21:E4654. [PMID: 32629928 PMCID: PMC7369703 DOI: 10.3390/ijms21134654] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 02/07/2023] Open
Abstract
Glycosylation is an important post-translational modification for both intracellular and secreted proteins. For glycosylation to occur, cargo must be transported after synthesis through the different compartments of the Golgi apparatus where distinct monosaccharides are sequentially bound and trimmed, resulting in increasingly complex branched glycan structures. Of utmost importance for this process is the intraorganellar environment of the Golgi. Each Golgi compartment has a distinct pH, which is maintained by the vacuolar H+-ATPase (V-ATPase). Moreover, tethering factors such as Golgins and the conserved oligomeric Golgi (COG) complex, in concert with coatomer (COPI) and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion, efficiently deliver glycosylation enzymes to the right Golgi compartment. Together, these factors maintain intra-Golgi trafficking of proteins involved in glycosylation and thereby enable proper glycosylation. However, pathogenic mutations in these factors can cause defective glycosylation and lead to diseases with a wide variety of symptoms such as liver dysfunction and skin and bone disorders. Collectively, this group of disorders is known as congenital disorders of glycosylation (CDG). Recent technological advances have enabled the robust identification of novel CDGs related to membrane trafficking components. In this review, we highlight differences and similarities between membrane trafficking-related CDGs.
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Affiliation(s)
- Peter T. A. Linders
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
| | - Ella Peters
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
| | - Martin ter Beest
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
| | - Dirk J. Lefeber
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands
| | - Geert van den Bogaart
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands; (P.T.A.L.); (E.P.); (M.t.B.)
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
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16
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Peng W, Casey AK, Fernandez J, Carpinone EM, Servage KA, Chen Z, Li Y, Tomchick DR, Starai VJ, Orth K. A distinct inhibitory mechanism of the V-ATPase by Vibrio VopQ revealed by cryo-EM. Nat Struct Mol Biol 2020; 27:589-597. [PMID: 32424347 DOI: 10.1038/s41594-020-0429-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 04/01/2020] [Indexed: 12/18/2022]
Abstract
The Vibrio parahaemolyticus T3SS effector VopQ targets host-cell V-ATPase, resulting in blockage of autophagic flux and neutralization of acidic compartments. Here, we report the cryo-EM structure of VopQ bound to the Vo subcomplex of the V-ATPase. VopQ inserts into membranes and forms an unconventional pore while binding directly to subunit c of the V-ATPase membrane-embedded subcomplex Vo. We show that VopQ arrests yeast growth in vivo by targeting the immature Vo subcomplex in the endoplasmic reticulum (ER), thus providing insight into the observation that VopQ kills cells in the absence of a functional V-ATPase. VopQ is a bacterial effector that has been discovered to inhibit a host-membrane megadalton complex by coincidentally binding its target, inserting into a membrane and disrupting membrane potential. Collectively, our results reveal a mechanism by which bacterial effectors modulate host cell biology and provide an invaluable tool for future studies on V-ATPase-mediated membrane fusion and autophagy.
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Affiliation(s)
- Wei Peng
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Amanda K Casey
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jessie Fernandez
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Kelly A Servage
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Zhe Chen
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yang Li
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Vincent J Starai
- Department of Microbiology, University of Georgia, Athens, GA, USA
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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17
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Rao VK, Zavala G, Deb Roy A, Mains RE, Eipper BA. A pH-sensitive luminal His-cluster promotes interaction of PAM with V-ATPase along the secretory and endocytic pathways of peptidergic cells. J Cell Physiol 2018; 234:8683-8697. [PMID: 30317586 DOI: 10.1002/jcp.27528] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 09/11/2018] [Indexed: 01/18/2023]
Abstract
The biosynthetic and endocytic pathways of secretory cells are characterized by progressive luminal acidification, a process which is crucial for posttranslational modifications and membrane trafficking. This progressive fall in luminal pH is mainly achieved by the vacuolar-type-H+ ATPase (V-ATPase). V-ATPases are large, evolutionarily ancient rotary proton pumps that consist of a peripheral V1 complex, which hydrolyzes ATP, and an integral membrane V0 complex, which transports protons from the cytosol into the lumen. Upon sensing the desired luminal pH, V-ATPase activity is regulated by reversible dissociation of the complex into its V1 and V0 components. Molecular details of how intraluminal pH is sensed and transmitted to the cytosol are not fully understood. Peptidylglycine α-amidating mono-oxygenase (PAM; EC 1.14.17.3), a secretory pathway membrane enzyme which shares similar topology with two V-ATPase accessory proteins (Ac45 and prorenin receptor), has a pH-sensitive luminal linker region. Immunofluorescence and sucrose gradient analysis of peptidergic cells (AtT-20) identified distinct subcellular compartments exhibiting spatial co-occurrence of PAM and V-ATPase. In vitro binding assays demonstrated direct binding of the cytosolic domain of PAM to V1H. Blue native PAGE identified heterogeneous high-molecular weight complexes of PAM and V-ATPase. A PAM-1 mutant (PAM-1/H3A) with altered pH sensitivity had diminished ability to form high-molecular weight complexes. In addition, V-ATPase assembly status was altered in PAM-1/H3A expressing cells. Our analysis of the secretory and endocytic pathways of peptidergic cells supports the hypothesis that PAM serves as a luminal pH-sensor, regulating V-ATPase action by altering its assembly status.
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Affiliation(s)
- Vishwanatha K Rao
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Gerardo Zavala
- Department of Chemistry, University of Texas at El Paso, El Paso, Texas
| | - Abhijit Deb Roy
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Betty A Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut.,Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut
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18
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Guida MC, Hermle T, Graham LA, Hauser V, Ryan M, Stevens TH, Simons M. ATP6AP2 functions as a V-ATPase assembly factor in the endoplasmic reticulum. Mol Biol Cell 2018; 29:2156-2164. [PMID: 29995586 PMCID: PMC6249795 DOI: 10.1091/mbc.e18-04-0234] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
ATP6AP2 (also known as the [pro]renin receptor) is a type I transmembrane protein that can be cleaved into two fragments in the Golgi apparatus. While in Drosophila ATP6AP2 functions in the planar cell polarity (PCP) pathway, recent human genetic studies have suggested that ATP6AP2 could participate in the assembly of the V-ATPase in the endoplasmic reticulum (ER). Using a yeast model, we show here that the V-ATPase assembly factor Voa1 can functionally be replaced by Drosophila ATP6AP2. This rescue is even more efficient when coexpressing its binding partner ATP6AP1, indicating that these two proteins together fulfill Voa1 functions in higher organisms. Structure–function analyses in both yeast and Drosophila show that proteolytic cleavage is dispensable, while C-terminus-dependent ER retrieval is required for ATP6AP2 function. Accordingly, we demonstrate that both overexpression and lack of ATP6AP2 causes ER stress in Drosophila wing cells and that the induction of ER stress is sufficient to cause PCP phenotypes. In summary, our results suggest that full-length ATP6AP2 contributes to the assembly of the V-ATPase proton pore and that impairment of this function affects ER homeostasis and PCP signaling.
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Affiliation(s)
- Maria Clara Guida
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, 75015 Paris, France.,Graduate Program GRK1104, University of Freiburg, 79106 Freiburg, Germany
| | - Tobias Hermle
- Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Laurie A Graham
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Virginie Hauser
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, 75015 Paris, France
| | - Margret Ryan
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Tom H Stevens
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Matias Simons
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, 75015 Paris, France
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19
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Graham LA, Finnigan GC, Kane PM. Some assembly required: Contributions of Tom Stevens' lab to the V-ATPase field. Traffic 2018; 19:385-390. [PMID: 29473670 DOI: 10.1111/tra.12559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/13/2018] [Accepted: 02/20/2018] [Indexed: 11/28/2022]
Abstract
Tom Stevens' lab has explored the subunit composition and assembly of the yeast V-ATPase for more than 30 years. Early studies helped establish yeast as the predominant model system for study of V-ATPase proton pumps and led to the discovery of protein splicing of the V-ATPase catalytic subunit. The Vma- phenotype, characteristic of loss-of-V-ATPase activity in yeast was key in determining the enzyme's subunit composition via yeast genetics. V-ATPase subunit composition proved to be highly conserved among eukaryotes. Genetic screens for new vma mutants led to identification of a set of dedicated V-ATPase assembly factors and helped unravel the complex pathways for V-ATPase assembly. In later years, exploration of the evolutionary history of several V-ATPase subunits provided new information about the enzyme's structure and function. This review highlights V-ATPase work in the Stevens' lab between 1987 and 2017.
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Affiliation(s)
- Laurie A Graham
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon
| | - Gregory C Finnigan
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York
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20
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Dharwada ST, Dalton LE, Bean BDM, Padmanabhan N, Choi C, Schluter C, Davey M, Conibear E. The chaperone Chs7 forms a stable complex with Chs3 and promotes its activity at the cell surface. Traffic 2018; 19:285-295. [DOI: 10.1111/tra.12553] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 01/29/2018] [Accepted: 01/31/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Sai T. Dharwada
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Lauren E. Dalton
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Björn D. M. Bean
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Nirmala Padmanabhan
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Catherine Choi
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Cayetana Schluter
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Michael Davey
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
| | - Elizabeth Conibear
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; University of British Columbia; Vancouver Canada
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21
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Deprez MA, Eskes E, Wilms T, Ludovico P, Winderickx J. pH homeostasis links the nutrient sensing PKA/TORC1/Sch9 ménage-à-trois to stress tolerance and longevity. MICROBIAL CELL 2018; 5:119-136. [PMID: 29487859 PMCID: PMC5826700 DOI: 10.15698/mic2018.03.618] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The plasma membrane H+-ATPase Pma1 and the vacuolar V-ATPase act in close harmony to tightly control pH homeostasis, which is essential for a vast number of physiological processes. As these main two regulators of pH are responsive to the nutritional status of the cell, it seems evident that pH homeostasis acts in conjunction with nutrient-induced signalling pathways. Indeed, both PKA and the TORC1-Sch9 axis influence the proton pumping activity of the V-ATPase and possibly also of Pma1. In addition, it recently became clear that the proton acts as a second messenger to signal glucose availability via the V-ATPase to PKA and TORC1-Sch9. Given the prominent role of nutrient signalling in longevity, it is not surprising that pH homeostasis has been linked to ageing and longevity as well. A first indication is provided by acetic acid, whose uptake by the cell induces toxicity and affects longevity. Secondly, vacuolar acidity has been linked to autophagic processes, including mitophagy. In agreement with this, a decline in vacuolar acidity was shown to induce mitochondrial dysfunction and shorten lifespan. In addition, the asymmetric inheritance of Pma1 has been associated with replicative ageing and this again links to repercussions on vacuolar pH. Taken together, accumulating evidence indicates that pH homeostasis plays a prominent role in the determination of ageing and longevity, thereby providing new perspectives and avenues to explore the underlying molecular mechanisms.
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Affiliation(s)
| | - Elja Eskes
- Functional Biology, KU Leuven, Leuven, Belgium
| | | | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
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22
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Esmail S, Kartner N, Yao Y, Kim JW, Reithmeier RAF, Manolson MF. Molecular mechanisms of cutis laxa- and distal renal tubular acidosis-causing mutations in V-ATPase a subunits, ATP6V0A2 and ATP6V0A4. J Biol Chem 2018; 293:2787-2800. [PMID: 29311258 DOI: 10.1074/jbc.m117.818872] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/20/2017] [Indexed: 12/19/2022] Open
Abstract
The a subunit is the largest of 15 different subunits that make up the vacuolar H+-ATPase (V-ATPase) complex, where it functions in proton translocation. In mammals, this subunit has four paralogous isoforms, a1-a4, which may encode signals for targeting assembled V-ATPases to specific intracellular locations. Despite the functional importance of the a subunit, its structure remains controversial. By studying molecular mechanisms of human disease-causing missense mutations within a subunit isoforms, we may identify domains critical for V-ATPase targeting, activity and/or regulation. cDNA-encoded FLAG-tagged human wildtype ATP6V0A2 (a2) and ATP6V0A4 (a4) subunits and their mutants, a2P405L (causing cutis laxa), and a4R449H and a4G820R (causing renal tubular acidosis, dRTA), were transiently expressed in HEK 293 cells. N-Glycosylation was assessed using endoglycosidases, revealing that a2P405L, a4R449H, and a4G820R were fully N-glycosylated. Cycloheximide (CHX) chase assays revealed that a2P405L and a4R449H were unstable relative to wildtype. a4R449H was degraded predominantly in the proteasomal pathway, whereas a2P405L was degraded in both proteasomal and lysosomal pathways. Immunofluorescence studies disclosed retention in the endoplasmic reticulum and defective cell-surface expression of a4R449H and defective Golgi trafficking of a2P405L Co-immunoprecipitation studies revealed an increase in association of a4R449H with the V0 assembly factor VMA21, and a reduced association with the V1 sector subunit, ATP6V1B1 (B1). For a4G820R, where stability, degradation, and trafficking were relatively unaffected, 3D molecular modeling suggested that the mutation causes dRTA by blocking the proton pathway. This study provides critical information that may assist rational drug design to manage dRTA and cutis laxa.
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Affiliation(s)
- Sally Esmail
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | - Norbert Kartner
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | - Yeqi Yao
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | - Joo Wan Kim
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6
| | | | - Morris F Manolson
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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23
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Rujano MA, Cannata Serio M, Panasyuk G, Péanne R, Reunert J, Rymen D, Hauser V, Park JH, Freisinger P, Souche E, Guida MC, Maier EM, Wada Y, Jäger S, Krogan NJ, Kretz O, Nobre S, Garcia P, Quelhas D, Bird TD, Raskind WH, Schwake M, Duvet S, Foulquier F, Matthijs G, Marquardt T, Simons M. Mutations in the X-linked ATP6AP2 cause a glycosylation disorder with autophagic defects. J Exp Med 2017; 214:3707-3729. [PMID: 29127204 PMCID: PMC5716037 DOI: 10.1084/jem.20170453] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 08/01/2017] [Accepted: 09/22/2017] [Indexed: 12/25/2022] Open
Abstract
Rujano et al. report mutations in ATP6AP2 leading to liver disease, immunodeficiency, and psychomotor impairment. ATP6AP2 deficiency impairs the assembly and function of the V-ATPase proton pump, causing defects in protein glycosylation and autophagy. The biogenesis of the multi-subunit vacuolar-type H+-ATPase (V-ATPase) is initiated in the endoplasmic reticulum with the assembly of the proton pore V0, which is controlled by a group of assembly factors. Here, we identify two hemizygous missense mutations in the extracellular domain of the accessory V-ATPase subunit ATP6AP2 (also known as the [pro]renin receptor) responsible for a glycosylation disorder with liver disease, immunodeficiency, cutis laxa, and psychomotor impairment. We show that ATP6AP2 deficiency in the mouse liver caused hypoglycosylation of serum proteins and autophagy defects. The introduction of one of the missense mutations into Drosophila led to reduced survival and altered lipid metabolism. We further demonstrate that in the liver-like fat body, the autophagic dysregulation was associated with defects in lysosomal acidification and mammalian target of rapamycin (mTOR) signaling. Finally, both ATP6AP2 mutations impaired protein stability and the interaction with ATP6AP1, a member of the V0 assembly complex. Collectively, our data suggest that the missense mutations in ATP6AP2 lead to impaired V-ATPase assembly and subsequent defects in glycosylation and autophagy.
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Affiliation(s)
- Maria A Rujano
- Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Magda Cannata Serio
- Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Ganna Panasyuk
- Institut Necker-Enfants Malades, Paris, France.,Institut National de la Santé et de la Recherche Medicale U1151/Centre National de la Recherche Scientifique UMR 8253, Paris, France
| | - Romain Péanne
- University of Leuven (KU Leuven), Center for Human Genetics, Leuven, Belgium
| | - Janine Reunert
- Universitätsklinikum Münster, Klinik für Kinder- und Jugendmedizin, Münster, Germany
| | - Daisy Rymen
- University of Leuven (KU Leuven), Center for Human Genetics, Leuven, Belgium
| | - Virginie Hauser
- Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris, France.,Institut National de la Santé et de la Recherche Medicale U1151/Centre National de la Recherche Scientifique UMR 8253, Paris, France
| | - Julien H Park
- Universitätsklinikum Münster, Klinik für Kinder- und Jugendmedizin, Münster, Germany
| | - Peter Freisinger
- Kreiskliniken Reutlingen, Klinik für Kinder- und Jugendmedizin, Klinikum am Steinenberg, Reutlingen, Germany
| | - Erika Souche
- University of Leuven (KU Leuven), Center for Human Genetics, Leuven, Belgium
| | - Maria Clara Guida
- Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris, France.,Institut National de la Santé et de la Recherche Medicale U1151/Centre National de la Recherche Scientifique UMR 8253, Paris, France
| | - Esther M Maier
- Dr. von Haunersches Kinderspital der Universität München, München, Germany
| | - Yoshinao Wada
- Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Stefanie Jäger
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA
| | - Oliver Kretz
- Centre for Biological Signaling Studies BIOSS, University of Freiburg, Freiburg, Germany
| | - Susana Nobre
- Metabolic Reference Center, Coimbra University Hospital Center, Coimbra, Portugal
| | - Paula Garcia
- Metabolic Reference Center, Coimbra University Hospital Center, Coimbra, Portugal
| | - Dulce Quelhas
- Biochemical Genetics Unit, Centro de Genética Médica Doutor Jacinto Magalhães, Centro Hospitalar do Porto, Abel Salazar Institute of Biomedical Sciences, University of Porto, Porto, Portugal
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, WA.,Geriatric Research Center, Veterans Administration Medical Center, Seattle, WA
| | - Wendy H Raskind
- Department of Medicine, University of Washington, Seattle, WA
| | - Michael Schwake
- Faculty of Chemistry/Biochemistry III, University Bielefeld, Bielefeld, Germany
| | - Sandrine Duvet
- Université Lille, Centre National de la Recherche Scientifique UMR 8576, Unité de Glycobiologie Structurale et Fonctionnelle, Lille, France
| | - Francois Foulquier
- Université Lille, Centre National de la Recherche Scientifique UMR 8576, Unité de Glycobiologie Structurale et Fonctionnelle, Lille, France
| | - Gert Matthijs
- University of Leuven (KU Leuven), Center for Human Genetics, Leuven, Belgium
| | - Thorsten Marquardt
- Universitätsklinikum Münster, Klinik für Kinder- und Jugendmedizin, Münster, Germany
| | - Matias Simons
- Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris, France .,Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
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24
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Munteanu I, Kalimo H, Saraste A, Nishino I, Minassian BA. Cardiac autophagic vacuolation in severe X-linked myopathy with excessive autophagy. Neuromuscul Disord 2017; 27:185-187. [DOI: 10.1016/j.nmd.2016.10.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 08/19/2016] [Accepted: 10/17/2016] [Indexed: 12/24/2022]
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25
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Colacurcio DJ, Nixon RA. Disorders of lysosomal acidification-The emerging role of v-ATPase in aging and neurodegenerative disease. Ageing Res Rev 2016; 32:75-88. [PMID: 27197071 DOI: 10.1016/j.arr.2016.05.004] [Citation(s) in RCA: 314] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/02/2016] [Accepted: 05/13/2016] [Indexed: 12/21/2022]
Abstract
Autophagy and endocytosis deliver unneeded cellular materials to lysosomes for degradation. Beyond processing cellular waste, lysosomes release metabolites and ions that serve signaling and nutrient sensing roles, linking the functions of the lysosome to various pathways for intracellular metabolism and nutrient homeostasis. Each of these lysosomal behaviors is influenced by the intraluminal pH of the lysosome, which is maintained in the low acidic range by a proton pump, the vacuolar ATPase (v-ATPase). New reports implicate altered v-ATPase activity and lysosomal pH dysregulation in cellular aging, longevity, and adult-onset neurodegenerative diseases, including forms of Parkinson disease and Alzheimer disease. Genetic defects of subunits composing the v-ATPase or v-ATPase-related proteins occur in an increasingly recognized group of familial neurodegenerative diseases. Here, we review the expanding roles of the v-ATPase complex as a platform regulating lysosomal hydrolysis and cellular homeostasis. We discuss the unique vulnerability of neurons to persistent low level lysosomal dysfunction and review recent clinical and experimental studies that link dysfunction of the v-ATPase complex to neurodegenerative diseases across the age spectrum.
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26
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Jansen EJR, Timal S, Ryan M, Ashikov A, van Scherpenzeel M, Graham LA, Mandel H, Hoischen A, Iancu TC, Raymond K, Steenbergen G, Gilissen C, Huijben K, van Bakel NHM, Maeda Y, Rodenburg RJ, Adamowicz M, Crushell E, Koenen H, Adams D, Vodopiutz J, Greber-Platzer S, Müller T, Dueckers G, Morava E, Sykut-Cegielska J, Martens GJM, Wevers RA, Niehues T, Huynen MA, Veltman JA, Stevens TH, Lefeber DJ. ATP6AP1 deficiency causes an immunodeficiency with hepatopathy, cognitive impairment and abnormal protein glycosylation. Nat Commun 2016; 7:11600. [PMID: 27231034 PMCID: PMC4894975 DOI: 10.1038/ncomms11600] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 04/12/2016] [Indexed: 02/07/2023] Open
Abstract
The V-ATPase is the main regulator of intra-organellar acidification. Assembly of this complex has extensively been studied in yeast, while limited knowledge exists for man. We identified 11 male patients with hemizygous missense mutations in ATP6AP1, encoding accessory protein Ac45 of the V-ATPase. Homology detection at the level of sequence profiles indicated Ac45 as the long-sought human homologue of yeast V-ATPase assembly factor Voa1. Processed wild-type Ac45, but not its disease mutants, restored V-ATPase-dependent growth in Voa1 mutant yeast. Patients display an immunodeficiency phenotype associated with hypogammaglobulinemia, hepatopathy and a spectrum of neurocognitive abnormalities. Ac45 in human brain is present as the common, processed ∼40-kDa form, while liver shows a 62-kDa intact protein, and B-cells a 50-kDa isoform. Our work unmasks Ac45 as the functional ortholog of yeast V-ATPase assembly factor Voa1 and reveals a novel link of tissue-specific V-ATPase assembly with immunoglobulin production and cognitive function.
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Affiliation(s)
- Eric J. R. Jansen
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience and Radboud Institute for Molecular Life Sciences, Faculty of Science, Radboud University, 6525 GA Nijmegen, The Netherlands
| | - Sharita Timal
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Margret Ryan
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
| | - Angel Ashikov
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Monique van Scherpenzeel
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Laurie A. Graham
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
| | - Hanna Mandel
- Metabolic Unit, Rambam Health Care Center, Rappaport School of Medicine, Technion, 3109601 Haifa, Israel
| | - Alexander Hoischen
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences and Donders Centre for Neuroscience, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Theodore C. Iancu
- The Milman-David Biomedical Research Unit, 24 Hazevi Avenue, 34355 Haifa, Israel
| | - Kimiyo Raymond
- Department of Laboratory Medicine and Pathology, Mayo College of Medicine, Rochester, Minnesota 55905, USA
| | - Gerry Steenbergen
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences and Donders Centre for Neuroscience, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Karin Huijben
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Nick H. M. van Bakel
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience and Radboud Institute for Molecular Life Sciences, Faculty of Science, Radboud University, 6525 GA Nijmegen, The Netherlands
| | - Yusuke Maeda
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Richard J. Rodenburg
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Pediatrics, Nijmegen Centre for Mitochondrial Disorders (NCMD), Radboud university medical center, 6525 GA Nijmegen, The Netherlands
| | - Maciej Adamowicz
- Protein Laboratory, Children's Memorial Health Institute, 04730 Warsaw, Poland
| | - Ellen Crushell
- Temple Street Children's University Hospital, Temple Street, Dublin 1, DC01 YC67, Ireland
| | - Hans Koenen
- Department of Laboratory Medicine, Medical Immunology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Darius Adams
- Personalized Genomic Medicine Pediatric Genetics and Metabolism Goryeb Children's Hospital, Morristown, New Jersey 07960, USA
| | - Julia Vodopiutz
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Susanne Greber-Platzer
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Thomas Müller
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Gregor Dueckers
- HELIOS Kliniken Krefeld, Children's Hospital, Lutherplatz 40, 47805 Krefeld, Germany
| | - Eva Morava
- Department of Pediatrics, Tulane University Medical School, New Orleans, Los Angeles 70112, USA
- Department of Pediatrics, University Medical School of Leuven, 3000 Leuven, Belgium
- Department of Pediatrics, Radboudumc, 6525GA, Nijmegen, The Netherlands
| | | | - Gerard J. M. Martens
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience and Radboud Institute for Molecular Life Sciences, Faculty of Science, Radboud University, 6525 GA Nijmegen, The Netherlands
| | - Ron A. Wevers
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Tim Niehues
- HELIOS Kliniken Krefeld, Children's Hospital, Lutherplatz 40, 47805 Krefeld, Germany
| | - Martijn A. Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands
| | - Joris A. Veltman
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences and Donders Centre for Neuroscience, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Clinical Genetics, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands
| | - Tom H. Stevens
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
| | - Dirk J. Lefeber
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
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Lee M, Ko YJ, Moon Y, Han M, Kim HW, Lee SH, Kang K, Jun Y. SNAREs support atlastin-mediated homotypic ER fusion in Saccharomyces cerevisiae. J Cell Biol 2015. [PMID: 26216899 PMCID: PMC4523606 DOI: 10.1083/jcb.201501043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dynamin-like GTPases of the atlastin family are thought to mediate homotypic endoplasmic reticulum (ER) membrane fusion; however, the underlying mechanism remains largely unclear. Here, we developed a simple and quantitative in vitro assay using isolated yeast microsomes for measuring yeast atlastin Sey1p-dependent ER fusion. Using this assay, we found that the ER SNAREs Sec22p and Sec20p were required for Sey1p-mediated ER fusion. Consistently, ER fusion was significantly reduced by inhibition of Sec18p and Sec17p, which regulate SNARE-mediated membrane fusion. The involvement of SNAREs in Sey1p-dependent ER fusion was further supported by the physical interaction of Sey1p with Sec22p and Ufe1p, another ER SNARE. Furthermore, our estimation of the concentration of Sey1p on isolated microsomes, together with the lack of fusion between Sey1p proteoliposomes even with a 25-fold excess of the physiological concentration of Sey1p, suggests that Sey1p requires additional factors to support ER fusion in vivo. Collectively, our data strongly suggest that SNARE-mediated membrane fusion is involved in atlastin-initiated homotypic ER fusion.
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Affiliation(s)
- Miriam Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Young-Joon Ko
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Yeojin Moon
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Minsoo Han
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Hyung-Wook Kim
- College of Life Sciences, Sejong University, Seoul 143-747, Korea
| | - Sung Haeng Lee
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju 501-759, Korea
| | - KyeongJin Kang
- Department of Anatomy and Cell Biology, School of Medicine, Sungkyunkwan University, Suwon 440-746, Korea
| | - Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
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28
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Saccharomyces cerevisiae vacuolar H+-ATPase regulation by disassembly and reassembly: one structure and multiple signals. EUKARYOTIC CELL 2014; 13:706-14. [PMID: 24706019 DOI: 10.1128/ec.00050-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Vacuolar H(+)-ATPases (V-ATPases) are highly conserved ATP-driven proton pumps responsible for acidification of intracellular compartments. V-ATPase proton transport energizes secondary transport systems and is essential for lysosomal/vacuolar and endosomal functions. These dynamic molecular motors are composed of multiple subunits regulated in part by reversible disassembly, which reversibly inactivates them. Reversible disassembly is intertwined with glycolysis, the RAS/cyclic AMP (cAMP)/protein kinase A (PKA) pathway, and phosphoinositides, but the mechanisms involved are elusive. The atomic- and pseudo-atomic-resolution structures of the V-ATPases are shedding light on the molecular dynamics that regulate V-ATPase assembly. Although all eukaryotic V-ATPases may be built with an inherent capacity to reversibly disassemble, not all do so. V-ATPase subunit isoforms and their interactions with membrane lipids and a V-ATPase-exclusive chaperone influence V-ATPase assembly. This minireview reports on the mechanisms governing reversible disassembly in the yeast Saccharomyces cerevisiae, keeping in perspective our present understanding of the V-ATPase architecture and its alignment with the cellular processes and signals involved.
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29
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Kinouchi K, Ichihara A, Sano M, Sun-Wada GH, Wada Y, Ochi H, Fukuda T, Bokuda K, Kurosawa H, Yoshida N, Takeda S, Fukuda K, Itoh H. The role of individual domains and the significance of shedding of ATP6AP2/(pro)renin receptor in vacuolar H(+)-ATPase biogenesis. PLoS One 2013; 8:e78603. [PMID: 24223829 PMCID: PMC3817224 DOI: 10.1371/journal.pone.0078603] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 09/13/2013] [Indexed: 12/16/2022] Open
Abstract
The ATPase 6 accessory protein 2 (ATP6AP2)/(pro)renin receptor (PRR) is essential for the biogenesis of active vacuolar H+-ATPase (V-ATPase). Genetic deletion of ATP6AP2/PRR causes V-ATPase dysfunction and compromises vesicular acidification. Here, we characterized the domains of ATP6AP2/PRR involved in active V-ATPase biogenesis. Three forms of ATP6AP2/PRR were found intracellularly: full-length protein and the N- and C-terminal fragments of furin cleavage products, with the N-terminal fragment secreted extracellularly. Genetic deletion of ATP6AP2/PRR did not affect the protein stability of V-ATPase subunits. The extracellular domain (ECD) and transmembrane domain (TM) of ATP6AP2/PRR were indispensable for the biogenesis of active V-ATPase. A deletion mutant of ATP6AP2/PRR, which lacks exon 4-encoded amino acids inside the ECD (Δ4M) and causes X-linked mental retardation Hedera type (MRXSH) and X-linked parkinsonism with spasticity (XPDS) in humans, was defective as a V-ATPase-associated protein. Prorenin had no effect on the biogenesis of active V-ATPase. The cleavage of ATP6AP2/PRR by furin seemed also dispensable for the biogenesis of active V-ATPase. We conclude that the N-terminal ECD of ATP6AP2/PRR, which is also involved in binding to prorenin or renin, is required for the biogenesis of active V-ATPase. The V-ATPase assembly occurs prior to its delivery to the trans-Golgi network and hence shedding of ATP6AP2/PRR would not affect the biogenesis of active V-ATPase.
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Affiliation(s)
- Kenichiro Kinouchi
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Atsuhiro Ichihara
- Department of Endocrinology and Hypertension, Tokyo Women’s Medical University, Tokyo, Japan
- * E-mail:
| | - Motoaki Sano
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Ge-Hong Sun-Wada
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women’s College, Kyoto, Japan
| | - Yoh Wada
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Hiroki Ochi
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Toru Fukuda
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Kanako Bokuda
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Hideaki Kurosawa
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Naohiro Yoshida
- Department of Endocrinology and Hypertension, Tokyo Women’s Medical University, Tokyo, Japan
| | - Shu Takeda
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Keiichi Fukuda
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Hiroshi Itoh
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
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30
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Abstract
All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker's yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na(+) and K(+), the divalent cations, Ca(2+) and Mg(2+), and the trace metal ions, Fe(2+), Zn(2+), Cu(2+), and Mn(2+). Signal transduction pathways that are regulated by pH and Ca(2+) are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment.
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31
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Spang A. Retrograde traffic from the Golgi to the endoplasmic reticulum. Cold Spring Harb Perspect Biol 2013; 5:5/6/a013391. [PMID: 23732476 DOI: 10.1101/cshperspect.a013391] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Proteins to be secreted are transported from the endoplasmic reticulum (ER) to the Golgi apparatus. The transport of these proteins requires the localization and activity of proteins that create ER exit sites, coat proteins to collect cargo and to reshape the membrane into a transport container, and address labels--SNARE proteins--to target the vesicles specifically to the Golgi apparatus. In addition some proteins may need export chaperones or export receptors to enable their exit into transport vesicles. ER export factors, SNAREs, and misfolded Golgi-resident proteins must all be retrieved from the Golgi to the ER again. This retrieval is also part of the organellar homeostasis pathway essential to maintaining the identity of the ER and of the Golgi apparatus. In this review, I will discuss the different processes in retrograde transport from the Golgi to the ER and highlight the mechanistic insights we have obtained in the last couple of years.
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Affiliation(s)
- Anne Spang
- University of Basel, Biozentrum, Growth & Development, Klingelbergstrasse 70, 4056 Basel, Switzerland.
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VMA21 deficiency prevents vacuolar ATPase assembly and causes autophagic vacuolar myopathy. Acta Neuropathol 2013; 125:439-57. [PMID: 23315026 DOI: 10.1007/s00401-012-1073-6] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 11/20/2012] [Accepted: 12/05/2012] [Indexed: 12/23/2022]
Abstract
X-linked Myopathy with Excessive Autophagy (XMEA) is a childhood onset disease characterized by progressive vacuolation and atrophy of skeletal muscle. We show that XMEA is caused by hypomorphic alleles of the VMA21 gene, that VMA21 is the diverged human ortholog of the yeast Vma21p protein, and that like Vma21p, VMA21 is an essential assembly chaperone of the vacuolar ATPase (V-ATPase), the principal mammalian proton pump complex. Decreased VMA21 raises lysosomal pH which reduces lysosomal degradative ability and blocks autophagy. This reduces cellular free amino acids which leads to downregulation of the mTORC1 pathway, and consequent increased macroautophagy resulting in proliferation of large and ineffective autolysosomes that engulf sections of cytoplasm, merge, and vacuolate the cell. Our results uncover a novel mechanism of disease, namely macroautophagic overcompensation leading to cell vacuolation and tissue atrophy.
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Seidel T, Siek M, Marg B, Dietz KJ. Energization of vacuolar transport in plant cells and its significance under stress. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:57-131. [PMID: 23809435 DOI: 10.1016/b978-0-12-407696-9.00002-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plant vacuole is of prime importance in buffering environmental perturbations and in coping with abiotic stress caused by, for example, drought, salinity, cold, or UV. The large volume, the efficient integration in anterograde and retrograde vesicular trafficking, and the dynamic equipment with tonoplast transporters enable the vacuole to fulfill indispensible functions in cell biology, for example, transient and permanent storage, detoxification, recycling, pH and redox homeostasis, cell expansion, biotic defence, and cell death. This review first focuses on endomembrane dynamics and then summarizes the functions, assembly, and regulation of secretory and vacuolar proton pumps: (i) the vacuolar H(+)-ATPase (V-ATPase) which represents a multimeric complex of approximately 800 kDa, (ii) the vacuolar H(+)-pyrophosphatase, and (iii) the plasma membrane H(+)-ATPase. These primary proton pumps regulate the cytosolic pH and provide the driving force for secondary active transport. Carriers and ion channels modulate the proton motif force and catalyze uptake and vacuolar compartmentation of solutes and deposition of xenobiotics or secondary compounds such as flavonoids. ABC-type transporters directly energized by MgATP complement the transport portfolio that realizes the multiple functions in stress tolerance of plants.
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Affiliation(s)
- Thorsten Seidel
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany.
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34
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Finnigan GC, Cronan GE, Park HJ, Srinivasan S, Quiocho FA, Stevens TH. Sorting of the yeast vacuolar-type, proton-translocating ATPase enzyme complex (V-ATPase): identification of a necessary and sufficient Golgi/endosomal retention signal in Stv1p. J Biol Chem 2012; 287:19487-500. [PMID: 22496448 DOI: 10.1074/jbc.m112.343814] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit a of the yeast vacuolar-type, proton-translocating ATPase enzyme complex (V-ATPase) is responsible for both proton translocation and subcellular localization of this highly conserved molecular machine. Inclusion of the Vph1p isoform causes the V-ATPase complex to traffic to the vacuolar membrane, whereas incorporation of Stv1p causes continued cycling between the trans-Golgi and endosome. We previously demonstrated that this targeting information is contained within the cytosolic, N-terminal portion of V-ATPase subunit a (Stv1p). To identify residues responsible for sorting of the Golgi isoform of the V-ATPase, a random mutagenesis was performed on the N terminus of Stv1p. Subsequent characterization of mutant alleles led to the identification of a short peptide sequence, W(83)KY, that is necessary for proper Stv1p localization. Based on three-dimensional homology modeling to the Meiothermus ruber subunit I, we propose a structural model of the intact Stv1p-containing V-ATPase demonstrating the accessibility of the W(83)KY sequence to retrograde sorting machinery. Finally, we characterized the sorting signal within the context of a reconstructed Stv1p ancestor (Anc.Stv1). This evolutionary intermediate includes an endogenous W(83)KY sorting motif and is sufficient to compete with sorting of the native yeast Stv1p V-ATPase isoform. These data define a novel sorting signal that is both necessary and sufficient for trafficking of the V-ATPase within the Golgi/endosomal network.
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Affiliation(s)
- Gregory C Finnigan
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
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35
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Finnigan GC, Hanson-Smith V, Houser BD, Park HJ, Stevens TH. The reconstructed ancestral subunit a functions as both V-ATPase isoforms Vph1p and Stv1p in Saccharomyces cerevisiae. Mol Biol Cell 2011; 22:3176-91. [PMID: 21737673 PMCID: PMC3164464 DOI: 10.1091/mbc.e11-03-0244] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The vacuolar ATPase complex in yeast contains two isoforms of subunit a that dictate the subcellular localization of the V-ATPase enzyme. The most recent common ancestor of subunit a (Anc.a) is reconstructed, and its function and localization in modern Saccharomyces cerevisiae are characterized. Anc.a is able to replace both subunit a isoforms. The vacuolar-type, proton-translocating ATPase (V-ATPase) is a multisubunit enzyme responsible for organelle acidification in eukaryotic cells. Many organisms have evolved V-ATPase subunit isoforms that allow for increased specialization of this critical enzyme. Differential targeting of the V-ATPase to specific subcellular organelles occurs in eukaryotes from humans to budding yeast. In Saccharomyces cerevisiae, the two subunit a isoforms are the only difference between the two V-ATPase populations. Incorporation of Vph1p or Stv1p into the V-ATPase dictates the localization of the V-ATPase to the vacuole or late Golgi/endosome, respectively. A duplication event within fungi gave rise to two subunit a genes. We used ancestral gene reconstruction to generate the most recent common ancestor of Vph1p and Stv1p (Anc.a) and tested its function in yeast. Anc.a localized to both the Golgi/endosomal network and vacuolar membrane and acidified these compartments as part of a hybrid V-ATPase complex. Trafficking of Anc.a did not require retrograde transport from the late endosome to the Golgi that has evolved for retrieval of the Stv1p isoform. Rather, Anc.a localized to both structures through slowed anterograde transport en route to the vacuole. Our results suggest an evolutionary model that describes the differential localization of the two yeast V-ATPase isoforms.
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Affiliation(s)
- Gregory C Finnigan
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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36
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Abstract
Trafficking of newly synthesized cargo through the early secretory pathway defines and maintains the intracellular organization of eukaryotic cells as well as the organization of tissues and organs. The importance of this pathway is underlined by the increasing number of mutations in key components of the ER export machinery that are causative of a diversity of human diseases. Here we discuss the molecular mechanisms that dictate cargo selection during vesicle budding. While, in vitro reconstitution assays, unicellular organisms such as budding yeast, and mammalian cell culture still have much to offer in terms of gaining a full understanding of the molecular basis for secretory cargo export, such assays have to date been limited to analysis of smaller, freely diffusible cargoes. The export of large macromolecular complexes from the ER such as collagens (up to 300 nm) or lipoproteins (~500 nm) presents a clear problem in terms of maintaining both selectivity and efficiency of export. It has also become clear that in order to translate our knowledge of the molecular basis for ER export to a full understanding of the implications for normal development and disease progression, the use of metazoan models is essential. Combined, these approaches are now starting to shed light not only on the mechanisms of macromolecular cargo export from the ER but also reveal the implications of failure of this process to human development and disease.
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Affiliation(s)
- Katy Schmidt
- Cell Biology Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, UK.
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37
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A genome-wide enhancer screen implicates sphingolipid composition in vacuolar ATPase function in Saccharomyces cerevisiae. Genetics 2010; 187:771-83. [PMID: 21196517 DOI: 10.1534/genetics.110.125567] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The function of the vacuolar H(+)-ATPase (V-ATPase) enzyme complex is to acidify organelles; this process is critical for a variety of cellular processes and has implications in human disease. There are five accessory proteins that assist in assembly of the membrane portion of the complex, the V(0) domain. To identify additional elements that affect V-ATPase assembly, trafficking, or enzyme activity, we performed a genome-wide enhancer screen in the budding yeast Saccharomyces cerevisiae with two mutant assembly factor alleles, VMA21 with a dysfunctional ER retrieval motif (vma21QQ) and vma21QQ in combination with voa1Δ, a nonessential assembly factor. These alleles serve as sensitized genetic backgrounds that have reduced V-ATPase enzyme activity. Genes were identified from a variety of cellular pathways including a large number of trafficking-related components; we characterized two redundant gene pairs, HPH1/HPH2 and ORM1/ORM2. Both sets demonstrated synthetic growth defects in combination with the vma21QQ allele. A loss of either the HPH or ORM gene pairs alone did not result in a decrease in vacuolar acidification or defects in V-ATPase assembly. While the Hph proteins are not required for V-ATPase function, Orm1p and Orm2p are required for full V-ATPase enzyme function. Consistent with the documented role of the Orm proteins in sphingolipid regulation, we have found that inhibition of sphingolipid synthesis alleviates Orm-related growth defects.
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38
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Plattner H. How to Design a Highly Organized Cell: An Unexpectedly High Number of Widely Diversified SNARE Proteins Positioned at Strategic Sites in the Ciliate, Paramecium tetraurelia. Protist 2010; 161:497-516. [DOI: 10.1016/j.protis.2010.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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39
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Toei M, Saum R, Forgac M. Regulation and isoform function of the V-ATPases. Biochemistry 2010; 49:4715-23. [PMID: 20450191 DOI: 10.1021/bi100397s] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The vacuolar (H(+))-ATPases are ATP-dependent proton pumps that acidify intracellular compartments and, in some cases, transport protons across the plasma membrane of eukaryotic cells. Intracellular V-ATPases play an important role in normal physiological processes such as receptor-mediated endocytosis, intracellular membrane trafficking, pro-hormone processing, protein degradation, and the coupled uptake of small molecules, such as neurotransmitters. They also function in the entry of various pathogenic agents, including many envelope viruses, like influenza virus, and toxins, like anthrax toxin. Plasma membrane V-ATPases function in renal pH homeostasis, bone resorption and sperm maturation, and various disease processes, including renal tubular acidosis, osteopetrosis, and tumor metastasis. V-ATPases are composed of a peripheral V(1) domain containing eight different subunits that is responsible for ATP hydrolysis and an integral V(0) domain containing six different subunits that translocates protons. In mammalian cells, most of the V-ATPase subunits exist in multiple isoforms which are often expressed in a tissue specific manner. Isoforms of one of the V(0) subunits (subunit a) have been shown to possess information that targets the V-ATPase to distinct cellular destinations. Mutations in isoforms of subunit a lead to the human diseases osteopetrosis and renal tubular acidosis. A number of mechanisms are employed to regulate V-ATPase activity in vivo, including reversible dissociation of the V(1) and V(0) domains, control of the tightness of coupling of proton transport and ATP hydrolysis, and selective targeting of V-ATPases to distinct cellular membranes. Isoforms of subunit a are involved in regulation both via the control of coupling and via selective targeting. This review will begin with a brief introduction to the function, structure, and mechanism of the V-ATPases followed by a discussion of the role of V-ATPase subunit isoforms and the mechanisms involved in regulation of V-ATPase activity.
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Affiliation(s)
- Masashi Toei
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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40
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Plattner H. Membrane Trafficking in Protozoa. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 280:79-184. [DOI: 10.1016/s1937-6448(10)80003-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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41
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Affiliation(s)
- G Mazarei
- Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada.
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42
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In vitro reconstitution of ER-stress induced ATF6 transport in COPII vesicles. Proc Natl Acad Sci U S A 2009; 106:17775-80. [PMID: 19822759 DOI: 10.1073/pnas.0910342106] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transcription factor ATF6 is held as a membrane precursor in the endoplasmic reticulum (ER), and is transported and proteolytically processed in the Golgi apparatus under conditions of unfolded protein response stress. We show that during stress, ATF6 forms an interaction with COPII, the protein complex required for vesicular traffic of cargo proteins from the ER. Using an in vitro budding reaction that recapitulates the ER-stress induced transport of ATF6, we show that no cytoplasmic proteins other than COPII are necessary for transport. ATF6 is retained in the ER by association with the chaperone BiP (GRP78). In the in vitro reaction, the ATF6-BiP complex disassembles when membranes are treated with reducing agent and ATP. A hybrid protein with the ATF6 cytoplasmic domain replaced by a constitutive sorting signal (Sec22b SNARE) retains stress-responsive transport in vivo and in vitro. These results suggest that unfolded proteins or an ER luminal -SH reactive bond controls BiP-ATF6 stability and access of ATF6 to the COPII budding machinery.
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43
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Ediger B, Melman SD, Pappas DL, Finch M, Applen J, Parra KJ. The tether connecting cytosolic (N terminus) and membrane (C terminus) domains of yeast V-ATPase subunit a (Vph1) is required for assembly of V0 subunit d. J Biol Chem 2009; 284:19522-32. [PMID: 19473972 DOI: 10.1074/jbc.m109.013375] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
V-ATPases are molecular motors that reversibly disassemble in vivo. Anchored in the membrane is subunit a. Subunit a has a movable N terminus that switches positions during disassembly and reassembly. Deletions were made at residues securing the N terminus of subunit a (yeast isoform Vph1) to its membrane-bound C-terminal domain in order to understand the role of this conserved region for V-ATPase function. Shrinking of the tether made cells pH-sensitive (vma phenotype) because assembly of V(0) subunit d was harmed. Subunit d did not co-immunoprecipitate with subunit a and the c-ring. Cells contained pools of V(1) and V(0)(-d) that failed to form V(1)V(0), and very low levels of V-ATPase subunits were found at the membrane. Although subunit d expression was stable and at wild-type levels, growth defects were rescued by exogenous VMA6 (subunit d). Stable V(1)V(0) assembled after yeast cells were co-transformed with VMA6 and mutant VPH1. Tether-less V(1)V(0) was delivered to the vacuole and active. It retained 63-71% of the wild-type activity and was responsive to glucose. Tether-less V(1)V(0) disassembled and reassembled after brief glucose depletion and readdition. The N terminus retained binding to V(1) subunits and the C terminus to phosphofructokinase. Thus, no major structural change was generated at the N and C termini of subunit a. We concluded that early steps of V(0) assembly and trafficking were likely impaired by shorter tethers and rescued by VMA6.
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Affiliation(s)
- Benjamin Ediger
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA
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44
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Guillard M, Dimopoulou A, Fischer B, Morava E, Lefeber DJ, Kornak U, Wevers RA. Vacuolar H+-ATPase meets glycosylation in patients with cutis laxa. Biochim Biophys Acta Mol Basis Dis 2009; 1792:903-14. [PMID: 19171192 DOI: 10.1016/j.bbadis.2008.12.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 12/22/2008] [Accepted: 12/29/2008] [Indexed: 02/08/2023]
Abstract
Glycosylation of proteins is one of the most important post-translational modifications. Defects in the glycan biosynthesis result in congenital malformation syndromes, also known as congenital disorders of glycosylation (CDG). Based on the iso-electric focusing patterns of plasma transferrin and apolipoprotein C-III a combined defect in N- and O-glycosylation was identified in patients with autosomal recessive cutis laxa type II (ARCL II). Disease-causing mutations were identified in the ATP6V0A2 gene, encoding the a2 subunit of the vacuolar H(+)-ATPase (V-ATPase). The V-ATPases are multi-subunit, ATP-dependent proton pumps located in membranes of cells and organels. In this article, we describe the structure, function and regulation of the V-ATPase and the phenotypes currently known to result from V-ATPase mutations. A clinical overview of cutis laxa syndromes is presented with a focus on ARCL II. Finally, the relationship between ATP6V0A2 mutations, the glycosylation defect and the ARCLII phenotype is discussed.
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Affiliation(s)
- Mailys Guillard
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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45
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Ryan M, Graham LA, Stevens TH. Voa1p functions in V-ATPase assembly in the yeast endoplasmic reticulum. Mol Biol Cell 2008; 19:5131-42. [PMID: 18799613 DOI: 10.1091/mbc.e08-06-0629] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The yeast Saccharomyces cerevisiae vacuolar ATPase (V-ATPase) is a multisubunit complex divided into two sectors: the V(1) sector catalyzes ATP hydrolysis and the V(0) sector translocates protons, resulting in acidification of its resident organelle. Four protein factors participate in V(0) assembly. We have discovered a fifth V(0) assembly factor, Voa1p (YGR106C); an endoplasmic reticulum (ER)-localized integral membrane glycoprotein. The role of Voa1p in V(0) assembly was revealed in cells expressing an ER retrieval-deficient form of the V-ATPase assembly factor Vma21p (Vma21pQQ). Loss of Voa1p in vma21QQ yeast cells resulted in loss of V-ATPase function; cells were unable to acidify their vacuoles and exhibited growth defects typical of cells lacking V-ATPase. V(0) assembly was severely compromised in voa1 vma21QQ double mutants. Isolation of V(0)-Vma21p complexes indicated that Voa1p associates most strongly with Vma21p and the core proteolipid ring of V(0) subunits c, c', and c''. On assembly of the remaining three V(0) subunits (a, d, and e) into the V(0) complex, Voa1p dissociates from the now fully assembled V(0)-Vma21p complex. Our results suggest Voa1p functions with Vma21p early in V(0) assembly in the ER, but then it dissociates before exit of the V(0)-Vma21p complex from the ER for transport to the Golgi compartment.
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Affiliation(s)
- Margret Ryan
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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46
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Neubert C, Graham LA, Black-Maier EW, Coonrod EM, Liu TY, Stierhof YD, Seidel T, Stevens TH, Schumacher K. Arabidopsis has two functional orthologs of the yeast V-ATPase assembly factor Vma21p. Traffic 2008; 9:1618-28. [PMID: 18694437 DOI: 10.1111/j.1600-0854.2008.00799.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
How individual protein subunits assemble into the higher order structure of a protein complex is not well understood. Four proteins dedicated to the assembly of the V(0) subcomplex of the V-adenosine triphosphatase (V-ATPase) in the endoplasmic reticulum (ER) have been identified in yeast, but their precise mode of molecular action remains to be identified. In contrast to the highly conserved subunits of the V-ATPase, orthologs of the yeast assembly factors are not easily identified based on sequence similarity. We show in this study that two ER-localized Arabidopsis proteins that share only 25% sequence identity with Vma21p can functionally replace this yeast assembly factor. Loss of AtVMA21a function in RNA interference seedlings caused impaired cell expansion and changes in Golgi morphology characteristic for plants with reduced V-ATPase activity, and we therefore conclude that AtVMA21a is the first V-ATPase assembly factor identified in a multicellular eukaryote. Moreover, VMA21p acts as a dedicated ER escort chaperone, a class of substrate-specific accessory proteins so far not identified in higher plants.
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Affiliation(s)
- Christoph Neubert
- Center for Plant Molecular Biology, ZMBP, University of Tübingen, Auf der Morgenstelle 1, 72076 Tübingen, Germany
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47
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Jefferies KC, Cipriano DJ, Forgac M. Function, structure and regulation of the vacuolar (H+)-ATPases. Arch Biochem Biophys 2008; 476:33-42. [PMID: 18406336 PMCID: PMC2543942 DOI: 10.1016/j.abb.2008.03.025] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 03/05/2008] [Accepted: 03/07/2008] [Indexed: 02/07/2023]
Abstract
The vacuolar ATPases (or V-ATPases) are ATP-driven proton pumps that function to both acidify intracellular compartments and to transport protons across the plasma membrane. Intracellular V-ATPases function in such normal cellular processes as receptor-mediated endocytosis, intracellular membrane traffic, prohormone processing, protein degradation and neurotransmitter uptake, as well as in disease processes, including infection by influenza and other viruses and killing of cells by anthrax and diphtheria toxin. Plasma membrane V-ATPases are important in such physiological processes as urinary acidification, bone resorption and sperm maturation as well as in human diseases, including osteopetrosis, renal tubular acidosis and tumor metastasis. V-ATPases are large multi-subunit complexes composed of a peripheral domain (V(1)) responsible for hydrolysis of ATP and an integral domain (V(0)) that carries out proton transport. Proton transport is coupled to ATP hydrolysis by a rotary mechanism. V-ATPase activity is regulated in vivo using a number of mechanisms, including reversible dissociation of the V(1) and V(0) domains, changes in coupling efficiency of proton transport and ATP hydrolysis and changes in pump density through reversible fusion of V-ATPase containing vesicles. V-ATPases are emerging as potential drug targets in treating a number of human diseases including osteoporosis and cancer.
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Affiliation(s)
| | | | - Michael Forgac
- Department of Physiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111
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48
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Rak M, Zeng X, Brière JJ, Tzagoloff A. Assembly of F0 in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:108-16. [PMID: 18672007 DOI: 10.1016/j.bbamcr.2008.07.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 06/26/2008] [Accepted: 07/01/2008] [Indexed: 11/30/2022]
Abstract
Respiratory deficient mutants of Saccharomyces cerevisiae have been instrumental in identifying an increasing number of nuclear gene products that promote pre- and post-translational steps of the pathway responsible for biogenesis of the mitochondrial ATP synthase. In this article we have attempted to marshal current information about the functions of such accessory factors and the roles they play in expression and assembly of the mitochondrially encoded subunits of the ATP synthase. We also discuss evidence that the ATP synthase may be built up from three separate modules corresponding to the F1 ATPase, the stator and F0.
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Affiliation(s)
- Malgorzata Rak
- Department of Biological Sciences, Columbia University New York, NY 10027, USA
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49
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Seidel T, Schnitzer D, Golldack D, Sauer M, Dietz KJ. Organelle-specific isoenzymes of plant V-ATPase as revealed by in vivo-FRET analysis. BMC Cell Biol 2008; 9:28. [PMID: 18507826 PMCID: PMC2424043 DOI: 10.1186/1471-2121-9-28] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 05/28/2008] [Indexed: 11/10/2022] Open
Abstract
Background The V-ATPase (VHA) is a protein complex of 13 different VHA-subunits. It functions as an ATP driven rotary-motor that electrogenically translocates H+ into endomembrane compartments. In Arabidopsis thaliana V-ATPase is encoded by 23 genes posing the question of specific versus redundant function of multigene encoded isoforms. Results The transmembrane topology and stoichiometry of the proteolipid VHA-c" as well as the stoichiometry of the membrane integral subunit VHA-e within the V-ATPase complex were investigated by in vivo fluorescence resonance energy transfer (FRET). VHA-c", VHA-e1 and VHA-e2, VHA-a, VHA-c3, truncated variants of VHA-c3 and a chimeric VHA-c/VHA-c" hybrid were fused to cyan (CFP) and yellow fluorescent protein (YFP), respectively. The constructs were employed for transfection experiments with Arabidopsis thaliana mesophyll protoplasts. Subcellular localization and FRET analysis by confocal laser scanning microscopy (CLSM) demonstrated that (i.) the N- and C-termini of VHA-c" are localised in the vacuolar lumen, (ii.) one copy of VHA-c" is present within the VHA-complex, and (iii.) VHA-c" is localised at the ER and associated Golgi bodies. (iv.) A similar localisation was observed for VHA-e2, whereas (v.) the subcellular localisation of VHA-e1 indicated the trans Golgi network (TGN)-specifity of this subunit. Conclusion The plant proteolipid ring is a highly flexible protein subcomplex, tolerating the incorporation of truncated and hybrid proteolipid subunits, respectively. Whereas the membrane integral subunit VHA-e is present in two copies within the complex, the proteolipid subunit VHA-c" takes part in complex formation with only one copy. However, neither VHA-c" isoform 1 nor any of the two VHA-e isoforms were identified at the tonoplast. This suggest a function in endomembrane specific VHA-assembly or targeting rather than proton transport.
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Affiliation(s)
- Thorsten Seidel
- Department of Biochemistry and Physiology of Plants, W5, University of Bielefeld, 33501 Bielefeld, Germany.
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Nuclear translocation of Gln3 in response to nutrient signals requires Golgi-to-endosome trafficking in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2008; 105:7194-9. [PMID: 18443284 DOI: 10.1073/pnas.0801087105] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The yeast Saccharomyces cerevisiae has developed specialized mechanisms that enable growth on suboptimal nitrogen sources. Exposure of yeast cells to poor nitrogen sources or treatment with the Tor kinase inhibitor rapamycin elicits activation of Gln3 and transcription of nitrogen catabolite-repressed (NCR) genes whose products function in scavenging and metabolizing nitrogen. Here, we show that mutations in class C and D Vps components, which mediate Golgi-to-endosome vesicle transport, impair nuclear translocation of Gln3, NCR gene activation, and growth in poor nitrogen sources. In nutrient-replete conditions, a significant fraction of Gln3 is peripherally associated with light membranes and partially colocalizes with Vps10-containing foci. These results reveal a role for Golgi-to-endosome vesicular trafficking in TORC1-controlled nuclear translocation of Gln3 and support a model in which Tor-mediated signaling in response to nutrient cues occurs in these compartments. These findings have important implications for nutrient sensing and growth control via mTor pathways in metazoans.
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