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Feng X, Wei G, Su Y, Xian Y, Liu Z, Gao Y, Liang J, Lian H, Xu J, Zhao J, Liu Q, Song F. Active fraction of Polyrhachis vicina (Rogers) inhibits osteoclastogenesis by targeting Trim38 mediated proteasomal degradation of TRAF6. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2024; 132:155890. [PMID: 39033726 DOI: 10.1016/j.phymed.2024.155890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/25/2024] [Accepted: 07/15/2024] [Indexed: 07/23/2024]
Abstract
BACKGROUND Reactive Oxygen Species (ROS) is a key factor in the pathogenesis of osteoporosis (OP) primarily characterized by excessive osteoclast activity. Active fraction of Polyrhachis vicina Rogers (AFPR) exerts antioxidant effects and possesses extensive promising therapeutic effects in various conditions, however, its function in osteoclastogenesis and OP is unknown. PURPOSE The aim of this study is to elucidate the cellular and molecular mechanisms of AFPR in OP. STUDY DESIGN AND METHODS CCK8 assay was used to evaluate the cell viability under AFPR treatment. TRAcP staining, podosome belts staining and bone resorption were used to test the effect of AFPR on osteoclastogenesis. Immunofluorescence staining was used to observe the effect of AFPR on ROS production. si-RNA transfection, coimmunoprecipitation and Western-blot were used to clarify the underlying mechanisms. Further, an ovariectomy (OVX) -induced OP mice model was used to identify the effect of AFPR on bone loss using Micro-CT scanning and histological examination. RESULTS In the present study, AFPR inhibited osteoclast differentiation and bone resorption induced by nuclear factor-κB receptor activator (NF-κB) ligand (RANKL) in dose-/ time-dependent with no cytotoxicity. Meanwhile, AFPR decreased RANKL-mediated ROS levels and enhanced ROS scavenging enzymes. Mechanistically, AFPR promoted proteasomal degradation of TRAF6 by significantly upregulating its K48-linked ubiquitination, subsequently inhibiting NFATc1 activity. We further observed that tripartite motif protein 38 (TRIM38) could mediate the ubiquitination of TRAF6 in response to RANKL. Moreover, TRIM38 could negatively regulate the RANKL pathway by binding to TRAF6 and promoting K48-linked polyubiquitination. In addition, TRIM38 deficiency rescued the inhibition of AFPR on ROS and NFATc1 activity and osteoclastogenesis. In line with these results, AFPR reduced OP caused by OVX through ameliorating osteoclastogenesis. CONCLUSION AFPR alleviates ovariectomized-induced bone loss via suppressing ROS and NFATc1 by targeting Trim38 mediated proteasomal degradation of TRAF6. The research offers innovative perspectives on AFPR's suppressive impact in vivo OVX mouse model and in vitro, and clarifies the fundamental mechanism.
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Affiliation(s)
- Xiaoliang Feng
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Guining Wei
- Department of Pharmacology, Guangxi Institute of Chinese Medicine and Pharmaceutical Science, Nanning, 530022, PR China
| | - Yuangang Su
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Yansi Xian
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Zhijuan Liu
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Yijie Gao
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Jiamin Liang
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Haoyu Lian
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Jiake Xu
- School of Biomedical Sciences, the University of Western Australia, Perth, Australia; Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China
| | - Jinmin Zhao
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China
| | - Qian Liu
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China.
| | - Fangming Song
- Guangxi Key Laboratory of Regenerative Medicine, Orthopaedics Trauma and Hand Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, PR China; Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, Guangxi, PR China.
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Jiang J, Ren R, Fang W, Miao J, Wen Z, Wang X, Xu J, Jin H. Lysosomal biogenesis and function in osteoclasts: a comprehensive review. Front Cell Dev Biol 2024; 12:1431566. [PMID: 39170917 PMCID: PMC11335558 DOI: 10.3389/fcell.2024.1431566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Accepted: 07/19/2024] [Indexed: 08/23/2024] Open
Abstract
Lysosomes serve as catabolic centers and signaling hubs in cells, regulating a multitude of cellular processes such as intracellular environment homeostasis, macromolecule degradation, intracellular vesicle trafficking and autophagy. Alterations in lysosomal level and function are crucial for cellular adaptation to external stimuli, with lysosome dysfunction being implicated in the pathogenesis of numerous diseases. Osteoclasts (OCs), as multinucleated cells responsible for bone resorption and maintaining bone homeostasis, have a complex relationship with lysosomes that is not fully understood. Dysregulated function of OCs can disrupt bone homeostasis leading to the development of various bone disorders. The regulation of OC differentiation and bone resorption for the treatment of bone disease have received considerable attention in recent years, yet the role and regulation of lysosomes in OCs, as well as the potential therapeutic implications of intervening in lysosomal biologic behavior for the treatment of bone diseases, remain relatively understudied. This review aims to elucidate the mechanisms involved in lysosomal biogenesis and to discuss the functions of lysosomes in OCs, specifically in relation to differentiation, bone resorption, and autophagy. Finally, we explore the potential therapeutic implication of targeting lysosomes in the treatment of bone metabolic disorders.
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Affiliation(s)
- Junchen Jiang
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Rufeng Ren
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Weiyuan Fang
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Jiansen Miao
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Zijun Wen
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Xiangyang Wang
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Jiake Xu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Haiming Jin
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
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Xiong L, Guo HH, Pan JX, Ren X, Lee D, Chen L, Mei L, Xiong WC. ATP6AP2, a regulator of LRP6/β-catenin protein trafficking, promotes Wnt/β-catenin signaling and bone formation in a cell type dependent manner. Bone Res 2024; 12:33. [PMID: 38811544 PMCID: PMC11137048 DOI: 10.1038/s41413-024-00335-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 03/06/2024] [Accepted: 04/08/2024] [Indexed: 05/31/2024] Open
Abstract
Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types, including osteoblast (OB) differentiation and function. Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive. ATP6AP2, an accessory subunit of V-ATPase, plays important roles in multiple cell types/organs and multiple signaling pathways. However, little is known whether and how ATP6AP2 in OBs regulates Wnt/β-catenin signaling and bone formation. Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions. Conditionally knocking out (CKO) ATP6AP2 in the OB-lineage cells (Atp6ap2Ocn-Cre) reduced trabecular, but not cortical, bone formation and bone mass. Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in ATP6AP2-KO BMSCs and OBs, but not osteocytes. Additional in vitro and in vivo studies revealed impaired β-catenin signaling in ATP6AP2-KO BMSCs and OBs, but not osteocytes, under both basal and Wnt stimulated conditions, although LRP5 was decreased in ATP6AP2-KO osteocytes, but not BMSCs. Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression of β-catenin phosphorylation, but necessary for LRP6/β-catenin and N-cadherin/β-catenin protein complex distribution at the cell membrane, thus preventing their degradation. Expression of active β-catenin diminished the OB differentiation deficit in ATP6AP2-KO BMSCs. Taken together, these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability, and thus regulating β-catenin levels, demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/β-catenin signaling and trabecular bone formation.
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Affiliation(s)
- Lei Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Louis Stoke VA Medical Center, Cleveland, OH, 44106, USA
| | - Hao-Han Guo
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Louis Stoke VA Medical Center, Cleveland, OH, 44106, USA
| | - Jin-Xiu Pan
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Louis Stoke VA Medical Center, Cleveland, OH, 44106, USA
| | - Xiao Ren
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Daehoon Lee
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
- Louis Stoke VA Medical Center, Cleveland, OH, 44106, USA
| | - Li Chen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
- Louis Stoke VA Medical Center, Cleveland, OH, 44106, USA.
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Alharbi H, Daniel EJP, Thies J, Chang I, Goldner DL, Ng BG, Witters P, Aqul A, Velez-Bartolomei F, Enns GM, Hsu E, Kichula E, Lee E, Lourenco C, Poskanzer SA, Rasmussen S, Saarela K, Wang YM, Raymond KM, Schultz MJ, Freeze HH, Lam C, Edmondson AC, He M. Fractionated plasma N-glycan profiling of novel cohort of ATP6AP1-CDG subjects identifies phenotypic association. J Inherit Metab Dis 2023; 46:300-312. [PMID: 36651831 PMCID: PMC10047170 DOI: 10.1002/jimd.12589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023]
Abstract
ATP6AP1-CDG is an X-linked disorder typically characterized by hepatopathy, immunodeficiency, and an abnormal type II transferrin glycosylation pattern. Here, we present 11 new patients and clinical updates with biochemical characterization on one previously reported patient. We also document intrafamilial phenotypic variability and atypical presentations, expanding the symptomatology of ATP6AP1-CDG to include dystonia, hepatocellular carcinoma, and lysosomal abnormalities on hepatic histology. Three of our subjects received successful liver transplantation. We performed N-glycan profiling of total and fractionated plasma proteins for six patients and show associations with varying phenotypes, demonstrating potential diagnostic and prognostic value of fractionated N-glycan profiles. The aberrant N-linked glycosylation in purified transferrin and remaining plasma glycoprotein fractions normalized in one patient post hepatic transplant, while the increases of Man4GlcNAc2 and Man5GlcNAc2 in purified immunoglobulins persisted. Interestingly, in the single patient with isolated immune deficiency phenotype, elevated high-mannose glycans were detected on purified immunoglobulins without glycosylation abnormalities on transferrin or the remaining plasma glycoprotein fractions. Given the diverse and often tissue specific clinical presentations and the need of clinical management post hepatic transplant in ATP6AP1-CDG patients, these results demonstrate that fractionated plasma N-glycan profiling could be a valuable tool in diagnosis and disease monitoring.
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Affiliation(s)
- Hana Alharbi
- Department of Pediatrics, Faculty of Medicine, University of Tabuk, Tabuk, Saudi Arabia
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Earnest James Paul Daniel
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Jenny Thies
- Division of Genetic Medicine, Seattle Children's Hospital, Seattle, Washington, USA
| | - Irene Chang
- Division of Genetic Medicine, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Dana L Goldner
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Columbia University Medical Center, New York, New York, USA
| | - Bobby G Ng
- Human Genetics Program, Sanford Burnham Prebys, La Jolla, California, USA
| | - Peter Witters
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Center for Metabolic Diseases, University Hospital Leuven, Leuven, Belgium
- Department of Development and Regeneration, Faculty of Medicine, KU Leuven, University Hospitals Leuven, Leuven, Belgium
| | - Amal Aqul
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, University of Texas Southwestern/Children's Medical Center, Dallas, Texas, USA
| | - Frances Velez-Bartolomei
- Genetics Section, San Jorge Children and Women's Hospital in San Juan, San Juan, Puerto Rico, USA
- Division of Medical Genetics, Department of Pediatrics, Lucile Packard Children's Hospital and Stanford University, Stanford, California, USA
| | - Gregory M Enns
- Division of Medical Genetics, Department of Pediatrics, Lucile Packard Children's Hospital and Stanford University, Stanford, California, USA
| | - Evelyn Hsu
- Division of Gastroenterology and Hepatology, Department of Pediatrics, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, Washington, USA
| | - Elizabeth Kichula
- Division of Neurology, Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia and the Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Esther Lee
- Genetic Services, Kaiser Permanente of Washington, Seattle, Washington, USA
| | - Charles Lourenco
- Faculdade de Medicina de São José do Rio Preto (FAMERP), São Jose do Rio Preto - São Paulo, Brazil
- Personalized Medicine area, Special Education Sector at DLE/Grupo Pardini, Belo Horizonte - MG, Brazil
| | - Sheri A Poskanzer
- St. Luke's Health System, Boise, Idaho, USA
- Department of Pediatrics, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Sara Rasmussen
- Transplant Center, Department of Surgery, Seattle Children's Hospital University of Washington School of Medicine Seattle, Seattle, Washington, USA
| | - Katelyn Saarela
- Division of Gastroenterology and Hepatology, Department of Pediatrics, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, Washington, USA
| | - YunZu M Wang
- Division of Bone Marrow Transplantation and Immune Deficiency, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio, USA
| | - Kimiyo M Raymond
- Department of Laboratory Medicine and Pathology, Laboratory Genetics and Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Matthew J Schultz
- Department of Laboratory Medicine and Pathology, Laboratory Genetics and Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Hudson H Freeze
- Human Genetics Program, Sanford Burnham Prebys, La Jolla, California, USA
| | - Christina Lam
- Division of Genetic Medicine, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Andrew C Edmondson
- Department of Pediatrics, Division of Human Genetics, Section of Metabolism, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Miao He
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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Zhang Y, Gao X, Bai X, Yao S, Chang YZ, Gao G. The emerging role of furin in neurodegenerative and neuropsychiatric diseases. Transl Neurodegener 2022; 11:39. [PMID: 35996194 PMCID: PMC9395820 DOI: 10.1186/s40035-022-00313-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 08/10/2022] [Indexed: 12/02/2022] Open
Abstract
Furin is an important mammalian proprotein convertase that catalyzes the proteolytic maturation of a variety of prohormones and proproteins in the secretory pathway. In the brain, the substrates of furin include the proproteins of growth factors, receptors and enzymes. Emerging evidence, such as reduced FURIN mRNA expression in the brains of Alzheimer's disease patients or schizophrenia patients, has implicated a crucial role of furin in the pathophysiology of neurodegenerative and neuropsychiatric diseases. Currently, compared to cancer and infectious diseases, the aberrant expression of furin and its pharmaceutical potentials in neurological diseases remain poorly understood. In this article, we provide an overview on the physiological roles of furin and its substrates in the brain, summarize the deregulation of furin expression and its effects in neurodegenerative and neuropsychiatric disorders, and discuss the implications and current approaches that target furin for therapeutic interventions. This review may expedite future studies to clarify the molecular mechanisms of furin deregulation and involvement in the pathogenesis of neurodegenerative and neuropsychiatric diseases, and to develop new diagnosis and treatment strategies for these diseases.
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Affiliation(s)
- Yi Zhang
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Laboratory of Molecular Iron Metabolism, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Xiaoqin Gao
- Shijiazhuang People's Hospital, Hebei Medical University, Shijiazhuang, 050027, China
| | - Xue Bai
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Laboratory of Molecular Iron Metabolism, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Shanshan Yao
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Laboratory of Molecular Iron Metabolism, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yan-Zhong Chang
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Laboratory of Molecular Iron Metabolism, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Guofen Gao
- Ministry of Education Key Laboratory of Molecular and Cellular Biology, Laboratory of Molecular Iron Metabolism, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
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Ponicidin Treatment Improved the Cell Proliferation, Differentiation, and Calcium Mineralization on the Osteoblast-Like MG-63 Cells. Appl Biochem Biotechnol 2022; 194:3860-3870. [PMID: 35556208 DOI: 10.1007/s12010-022-03927-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2022] [Indexed: 11/02/2022]
Abstract
Osteoporosis is a general bone-related ailment characterized by reduced bone density and quality, elevated bone fragility, and fractures. It was reported that both aged men and women has an increased risks of osteoporosis. The current research work focused to unveil the beneficial roles of ponicidin treatment in the proliferation and calcium deposition on the osteoblast-like MG-63 cells. The effect of 5 and 10 µg/ml of ponicidin on the cell proliferation was assessed. The viability of ponicidin-supplemented MG-63 cells was inspected by MTT test. The contents of osteocalcin, collagen, and ALP activity in the ponicidin administered cells were assessed by kits. The level of calcium mineralization was examined by ARS staining technique. The ponicidin treatment remarkably improved the proliferation of MG-63 cells. The ponicidin did not affect the MG-63 cells viability but promoted its viability 24- and 48-h treatment. The contents of osteocalcin, collagen, and ALP activity in the 5 and 10 µg/ml of ponicidin-supplemented MG-63 cells were found increased than the control cells. The ponicidin also increased the level of calcium deposition in MG-63 cells, which is assessed by ARS staining. In conclusion, it was clear that ponicidin improved the proliferation and calcium mineralization in a MG-63 cells. Therefore, it was clear that ponicidin has helpful roles on the new bone development as a hopeful therapeutic candidate to treat the bone-related disease like osteoporosis.
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Novel vertebrate- and brain-specific driver of neuronal outgrowth. Prog Neurobiol 2021; 202:102069. [PMID: 33933532 DOI: 10.1016/j.pneurobio.2021.102069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 03/31/2021] [Accepted: 04/21/2021] [Indexed: 12/30/2022]
Abstract
During the process of neuronal outgrowth, developing neurons produce new projections, neurites, that are essential for brain wiring. Here, we discover a relatively late-evolved protein that we denote Ac45-related protein (Ac45RP) and that, surprisingly, drives neuronal outgrowth. Ac45RP is a paralog of the Ac45 protein that is a component of the vacuolar proton ATPase (V-ATPase), the main pH regulator in eukaryotic cells. Ac45RP mRNA expression is brain specific and coincides with the peak of neurogenesis and the onset of synaptogenesis. Furthermore, Ac45RP physically interacts with the V-ATPase V0-sector and colocalizes with V0 in unconventional, but not synaptic, secretory vesicles of extending neurites. Excess Ac45RP enhances the expression of V0-subunits, causes a more elaborate Golgi, and increases the number of cytoplasmic vesicular structures, plasma membrane formation and outgrowth of actin-containing neurites devoid of synaptic markers. CRISPR-cas9n-mediated Ac45RP knockdown reduces neurite outgrowth. We conclude that the novel vertebrate- and brain-specific Ac45RP is a V0-interacting constituent of unconventional vesicular structures that drives membrane expansion during neurite outgrowth and as such may furnish a tool for future neuroregenerative treatment strategies.
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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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Collins MP, Forgac M. Regulation and function of V-ATPases in physiology and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183341. [PMID: 32422136 DOI: 10.1016/j.bbamem.2020.183341] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 02/07/2023]
Abstract
The vacuolar H+-ATPases (V-ATPases) are essential, ATP-dependent proton pumps present in a variety of eukaryotic cellular membranes. Intracellularly, V-ATPase-dependent acidification functions in such processes as membrane traffic, protein degradation, autophagy and the coupled transport of small molecules. V-ATPases at the plasma membrane of certain specialized cells function in such processes as bone resorption, sperm maturation and urinary acidification. V-ATPases also function in disease processes such as pathogen entry and cancer cell invasiveness, while defects in V-ATPase genes are associated with disorders such as osteopetrosis, renal tubular acidosis and neurodegenerative diseases. This review highlights recent advances in our understanding of V-ATPase structure, mechanism, function and regulation, with an emphasis on the signaling pathways controlling V-ATPase assembly in mammalian cells. The role of V-ATPases in cancer and other human pathologies, and the prospects for therapeutic intervention, are also discussed.
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Affiliation(s)
- Michael P Collins
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America
| | - Michael Forgac
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America; Dept. of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, United States of America.
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10
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Tvina A, Thomsen A, Palatnik A. Prenatal and postnatal phenotype of a pathologic variant in the ATP6AP1 gene. Eur J Med Genet 2020; 63:103881. [PMID: 32058063 DOI: 10.1016/j.ejmg.2020.103881] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 01/19/2020] [Accepted: 02/09/2020] [Indexed: 02/07/2023]
Abstract
INTRODUCTION The ATP6AP1 gene encodes for ATPase H+ transporting protein. ATP6AP1 gene mutations are associated with congenital disorders of glycosylation (CDG) and can affect multiple organ system. Descriptions of postnatal phenotype include immunodeficiency, hepatopathy and cognitive impairment. No prenatal phenotype of these gene mutations has been described to date. CASE This is a description of the prenatal workup of an infant diagnosed with a X-linked ATP6AP1 gene mutation. First trimester ultrasound demonstrated a thickened nuchal translucency measured at 3.27 mm and dysmorphic spinal canal, corresponding to kyphoscoliosis finding postnatally. Findings from amniocentesis at 15 weeks included elevated amniotic fluid alpha-fetoprotein (AF-AFP) and positive acetylcholinesterase (AchE). Dilation of the aortic arch was seen on fetal echocardiogram at 20 weeks. Throughout the second trimester, a rim of fluid collection was seen under the skin covering the thoracic and lumbar fetal spine, consistent with a large Aplasia Cutis below the right scapula present at birth. CONCLUSION To our knowledge, this is the first description of prenatal phenotype of an X-linked ATP6AP1 gene mutation, and the association of this gene mutation with increased NT, elevated AF-AFP and AchE and Aplasia Cutis Congenita. This variant was submitted to ClinVar public database, submission ID: SUB6537411.
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Affiliation(s)
- Alina Tvina
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Allison Thomsen
- Department of Obstetrics and Gynecology, Division of Medical Genetics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Anna Palatnik
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI, USA.
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11
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Modi PK, Prabhu A, Bhandary YP, Shenoy P. S, Hegde A, ES SP, Johnson RP, Das SP, Vazirally S, Rekha PD. Effect of calcium glucoheptonate on proliferation and osteogenesis of osteoblast-like cells in vitro. PLoS One 2019; 14:e0222240. [PMID: 31498830 PMCID: PMC6733474 DOI: 10.1371/journal.pone.0222240] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 08/23/2019] [Indexed: 12/16/2022] Open
Abstract
Calcium is the key macromineral having a role in skeletal structure and function, muscle contraction, and neurotransmission. Bone remodeling is maintained through a constant balance between calcium resorption and deposition. Calcium deficiency is resolved through calcium supplementation, and among the supplements, water-soluble organic molecules attracted great pharmaceutical interest. Calcium glucoheptonate is a highly water-soluble organic calcium salt having clinical use; however, detailed investigations on its biological effects are limited. We assessed the effects of calcium glucoheptonate on cell viability and proliferation of osteoblast-like MG-63 cells. Calcium uptake and mineralization were evaluated using Alizarin red staining of osteoblast-like MG-63 cells treated with calcium glucoheptonate. Expression of osteogenic markers were monitored by western blotting, immunofluorescence, and qRT-PCR assays. Increased proliferation and calcium uptake were observed in the MG-63 cells treated with calcium glucoheptonate. The treatment also increased the expression of osteopontin and osteogenic genes such as collagen-1, secreted protein acidic and cysteine rich (SPARC), and osteocalcin. Calcium glucoheptonate treatment did not exert any cytotoxicity on colorectal and renal epithelial cells, indicating the safety of the treatment. This is the first report with evidence for its beneficial effect for pharmaceutical use in addressing calcium deficiency conditions.
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Affiliation(s)
- Prashant Kumar Modi
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Ashwini Prabhu
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Yashodhar P. Bhandary
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Sudheer Shenoy P.
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Aparna Hegde
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Sindhu Priya ES
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Renjith P. Johnson
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Shankar Prasad Das
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
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12
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Jansen JC, Wolthuis D, Van Scherpenzeel M, Ratziu V, Drenth JPH, Lefeber DJ. NAFLD Phenotype in Patients With V-ATPase Proton Pump Assembly Defects. Cell Mol Gastroenterol Hepatol 2018; 5:415-417.e1. [PMID: 29675453 PMCID: PMC5904036 DOI: 10.1016/j.jcmgh.2017.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
| | | | - Monique Van Scherpenzeel
- Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, HB Nijmegen, The Netherlands.,Institute for Cardiometabolism and Nutrition, Hôpital Pitié Salpêtrière, Service d'Hépatogastroentérologie, Université Pierre et Marie Curie, Paris, France.,Department of Gastroenterology and Hepatology, Radboud University Medical Center, GA Nijmegen, The Netherlands.,Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, HB Nijmegen, The Netherlands
| | - Vlad Ratziu
- Institute for Cardiometabolism and Nutrition, Hôpital Pitié Salpêtrière, Service d'Hépatogastroentérologie, Université Pierre et Marie Curie, Paris, France.,Department of Gastroenterology and Hepatology, Radboud University Medical Center, GA Nijmegen, The Netherlands.,Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, HB Nijmegen, The Netherlands
| | - Joost P H Drenth
- Department of Gastroenterology and Hepatology, Radboud University Medical Center, GA Nijmegen, The Netherlands.,Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, HB Nijmegen, The Netherlands
| | - Dirk J Lefeber
- Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, HB Nijmegen, The Netherlands
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13
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Holliday LS. Vacuolar H +-ATPases (V-ATPases) as therapeutic targets: a brief review and recent developments. ACTA ACUST UNITED AC 2017; 1. [PMID: 30957075 DOI: 10.21037/biotarget.2017.12.01] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Vacuolar H+-ATPases (V-ATPases) are multi-subunit enzymes that play housekeeping roles in eukaryotic cells by acidifying lysosomes, late endosomes, Golgi, and other membrane-bounded compartments. Beyond that, V-ATPases have specialized functions in certain cell types linked to diseases including osteoporosis and cancer. Efforts to identify strategies to develop inhibitors selective for V-ATPases that are involved in disease progression have been ongoing for more than two decades, but so far have not yielded a therapeutic agent that has been translated to the clinic. Recent basic science studies have identified unexpected roles for V-ATPases in nutrient and energy sensing, and renin/angiotensin signaling, which offer additional incentives for considering V-ATPases as therapeutic targets. This article briefly reviews efforts to utilize inhibitors of V-ATPases as drugs. Primary focus is on recent "rational" efforts to identify small molecule inhibitors of the V-ATPases that are selectively expressed in osteoclasts and cancer cells. Enoxacin and bis-enoxacin are two molecules that emerged from these efforts. These molecules block a binding interaction between V-ATPases and microfilaments that occurs in osteoclasts, but not most other cell types, which relates to the specialized function of V-ATPases in bone resorption. Enoxacin and bis-enoxacin have proven useful in the treatment of bone diseases and cancer in animal models and display therapeutic effects that are different, and perhaps better, than current drugs. These results provide evidence that agents targeting subsets of V-ATPases may prove useful in the clinic.
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Affiliation(s)
- L Shannon Holliday
- Departments of Orthodontics and Anatomy & Cell Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
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14
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Yadav KS, Miranda-Astudillo HV, Colina-Tenorio L, Bouillenne F, Degand H, Morsomme P, González-Halphen D, Boekema EJ, Cardol P. Atypical composition and structure of the mitochondrial dimeric ATP synthase from Euglena gracilis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:267-275. [DOI: 10.1016/j.bbabio.2017.01.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/22/2016] [Accepted: 01/10/2017] [Indexed: 11/26/2022]
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15
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Calmodulin interacts with Rab3D and modulates osteoclastic bone resorption. Sci Rep 2016; 6:37963. [PMID: 27897225 PMCID: PMC5126571 DOI: 10.1038/srep37963] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/03/2016] [Indexed: 11/09/2022] Open
Abstract
Calmodulin is a highly versatile protein that regulates intracellular calcium homeostasis and is involved in a variety of cellular functions including cardiac excitability, synaptic plasticity and signaling transduction. During osteoclastic bone resorption, calmodulin has been reported to concentrate at the ruffled border membrane of osteoclasts where it is thought to modulate bone resorption activity in response to calcium. Here we report an interaction between calmodulin and Rab3D, a small exocytic GTPase and established regulator osteoclastic bone resorption. Using yeast two-hybrid screening together with a series of protein-protein interaction studies, we show that calmodulin interacts with Rab3D in a calcium dependent manner. Consistently, expression of a calcium insensitive form of calmodulin (i.e. CaM1234) perturbs calmodulin-Rab3D interaction as monitored by bioluminescence resonance energy transfer (BRET) assays. In osteoclasts, calmodulin and Rab3D are constitutively co-expressed during RANKL-induced osteoclast differentiation, co-occupy plasma membrane fractions by differential gradient sedimentation assay and colocalise in the ruffled border as revealed by confocal microscopy. Further, functional blockade of calmodulin-Rab3D interaction by calmidazolium chloride coincides with an attenuation of osteoclastic bone resorption. Our data imply that calmodulin- Rab3D interaction is required for efficient bone resorption by osteoclasts in vitro.
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16
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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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17
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Smith GA, Howell GJ, Phillips C, Muench SP, Ponnambalam S, Harrison MA. Extracellular and Luminal pH Regulation by Vacuolar H+-ATPase Isoform Expression and Targeting to the Plasma Membrane and Endosomes. J Biol Chem 2016; 291:8500-15. [PMID: 26912656 PMCID: PMC4861423 DOI: 10.1074/jbc.m116.723395] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Indexed: 01/02/2023] Open
Abstract
Plasma membrane vacuolar H+-ATPase (V-ATPase) activity of tumor cells is a major factor in control of cytoplasmic and extracellular pH and metastatic potential, but the isoforms involved and the factors governing plasma membrane recruitment remain uncertain. Here, we examined expression, distribution, and activity of V-ATPase isoforms in invasive prostate adenocarcinoma (PC-3) cells. Isoforms 1 and 3 were the most highly expressed forms of membrane subunit a, with a1 and a3 the dominant plasma membrane isoforms. Correlation between plasma membrane V-ATPase activity and invasiveness was limited, but RNAi knockdown of either a isoform did slow cell proliferation and inhibit invasion in vitro. Isoform a1 was recruited to the cell surface from the early endosome-recycling complex pathway, its knockdown arresting transferrin receptor recycling. Isoform a3 was associated with the late endosomal/lysosomal compartment. Both a isoforms associated with accessory protein Ac45, knockdown of which stalled transit of a1 and transferrin-transferrin receptor, decreased proton efflux, and reduced cell growth and invasiveness; this latter effect was at least partly due to decreased delivery of the membrane-bound matrix metalloproteinase MMP-14 to the plasma membrane. These data indicate that in prostatic carcinoma cells, a1 and a3 isoform populations predominate in different compartments where they maintain different luminal pH. Ac45 plays a central role in navigating the V-ATPase to the plasma membrane, and hence it is an important factor in expression of the invasive phenotype.
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Affiliation(s)
- Gina A Smith
- From the Endothelial Cell Biology Unit, School of Molecular and Cellular Biology and
| | - Gareth J Howell
- From the Endothelial Cell Biology Unit, School of Molecular and Cellular Biology and
| | - Clair Phillips
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Michael A Harrison
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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18
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Zhu S, Rea SL, Cheng T, Feng HT, Walsh JP, Ratajczak T, Tickner J, Pavlos N, Xu HZ, Xu J. Bafilomycin A1 Attenuates Osteoclast Acidification and Formation, Accompanied by Increased Levels of SQSTM1/p62 Protein. J Cell Biochem 2015; 117:1464-70. [PMID: 27043248 DOI: 10.1002/jcb.25442] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/11/2015] [Indexed: 12/14/2022]
Abstract
Vacuolar proton pump H(+)-adenosine triphosphatases (V-ATPases) play an important role in osteoclast function. Further understanding of the cellular and molecular mechanisms of V-ATPase inhibition is vital for the development of anti-resorptive drugs specifically targeting osteoclast V-ATPases. In this study, we observed that bafilomycin A1, a naturally-occurring inhibitor of V-ATPases, increased the protein level of SQSTM1/p62, a known negative regulator of osteoclast formation. Consistently, we found that bafilomycin A1 diminishes the intracellular accumulation of the acidotropic probe lysotracker in osteoclast-like cells; indicative of reduced acidification. Further, bafilomycin A1 inhibits osteoclast formation with attenuation of cell fusion and multi-nucleation of osteoclast-like cells during osteoclast differentiation. Taken together, these data indicate that bafilomycin A1 attenuates osteoclast differentiation in part via increased levels of SQSTM1/p62 protein, providing further mechanistic insight into the effect of V-ATPase inhibition in osteoclasts.
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Affiliation(s)
- Sipin Zhu
- Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.,School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
| | - Sarah L Rea
- Laboratory for Molecular Endocrinology, Harry Perkins Institute of Medical Research and UWA Centre for Medical Research, The University of Western Australia, Crawley, WA, 6009, Australia.,Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Taksum Cheng
- School of Surgery, Centre of Orthopaedic Research, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Hao Tian Feng
- School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
| | - John P Walsh
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia.,School of Medicine and Pharmacology, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Thomas Ratajczak
- Laboratory for Molecular Endocrinology, Harry Perkins Institute of Medical Research and UWA Centre for Medical Research, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Jennifer Tickner
- School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
| | - Nathan Pavlos
- School of Surgery, Centre of Orthopaedic Research, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Hua-Zi Xu
- Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Jiake Xu
- Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.,School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
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19
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Perreira JM, Aker AM, Savidis G, Chin CR, McDougall WM, Portmann JM, Meraner P, Smith MC, Rahman M, Baker RE, Gauthier A, Franti M, Brass AL. RNASEK Is a V-ATPase-Associated Factor Required for Endocytosis and the Replication of Rhinovirus, Influenza A Virus, and Dengue Virus. Cell Rep 2015. [PMID: 26212330 DOI: 10.1016/j.celrep.2015.06.076] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Human rhinovirus (HRV) causes upper respiratory infections and asthma exacerbations. We screened multiple orthologous RNAi reagents and identified host proteins that modulate HRV replication. Here, we show that RNASEK, a transmembrane protein, was needed for the replication of HRV, influenza A virus, and dengue virus. RNASEK localizes to the cell surface and endosomal pathway and closely associates with the vacuolar ATPase (V-ATPase) proton pump. RNASEK is required for endocytosis, and its depletion produces enlarged clathrin-coated pits (CCPs) at the cell surface. These enlarged CCPs contain endocytic cargo and are bound by the scissioning GTPase, DNM2. Loss of RNASEK alters the localization of multiple V-ATPase subunits and lowers the levels of the ATP6AP1 subunit. Together, our results show that RNASEK closely associates with the V-ATPase and is required for its function; its loss prevents the early events of endocytosis and the replication of multiple pathogenic viruses.
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Affiliation(s)
- Jill M Perreira
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Aaron M Aker
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - George Savidis
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Christopher R Chin
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - William M McDougall
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Jocelyn M Portmann
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Paul Meraner
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Miles C Smith
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Motiur Rahman
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Richard E Baker
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA
| | - Annick Gauthier
- Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, Ridgefield, CT 06877, USA
| | - Michael Franti
- Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, Ridgefield, CT 06877, USA
| | - Abraham L Brass
- Microbiology and Physiological Systems Department, University of Massachusetts Medical School, University of Massachusetts, Worcester, MA 01655, USA.
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20
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Vacuolar H+-ATPase: An Essential Multitasking Enzyme in Physiology and Pathophysiology. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/675430] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Vacuolar H+-ATPases (V-ATPases) are large multisubunit proton pumps that are required for housekeeping acidification of membrane-bound compartments in eukaryotic cells. Mammalian V-ATPases are composed of 13 different subunits. Their housekeeping functions include acidifying endosomes, lysosomes, phagosomes, compartments for uncoupling receptors and ligands, autophagosomes, and elements of the Golgi apparatus. Specialized cells, including osteoclasts, intercalated cells in the kidney and pancreatic beta cells, contain both the housekeeping V-ATPases and an additional subset of V-ATPases, which plays a cell type specific role. The specialized V-ATPases are typically marked by the inclusion of cell type specific isoforms of one or more of the subunits. Three human diseases caused by mutations of isoforms of subunits have been identified. Cancer cells utilize V-ATPases in unusual ways; characterization of V-ATPases may lead to new therapeutic modalities for the treatment of cancer. Two accessory proteins to the V-ATPase have been identified that regulate the proton pump. One is the (pro)renin receptor and data is emerging that indicates that V-ATPase may be intimately linked to renin/angiotensin signaling both systemically and locally. In summary, V-ATPases play vital housekeeping roles in eukaryotic cells. Specialized versions of the pump are required by specific organ systems and are involved in diseases.
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21
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Ng PY, Cheng TS, Zhao H, Ye S, Sm Ang E, Khor EC, Feng HT, Xu J, Zheng MH, Pavlos NJ. Disruption of the dynein-dynactin complex unveils motor-specific functions in osteoclast formation and bone resorption. J Bone Miner Res 2013; 28:119-34. [PMID: 22887640 DOI: 10.1002/jbmr.1725] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 07/02/2012] [Accepted: 07/27/2012] [Indexed: 12/22/2022]
Abstract
Osteoclastic bone resorption requires strict interplay between acidified carrier vesicles, motor proteins, and the underlying cytoskeleton in order to sustain the specialized structural and functional polarization of the ruffled border. Cytoplasmic dynein, a large processive mechanochemical motor comprising heavy, intermediate, and light chains coupled to the dynactin cofactor complex, powers unilateral motility of diverse cargos to microtubule minus-ends. We have recently shown that regulators of the dynein motor complex constitute critical components of the osteoclastic bone resorptive machinery. Here, by selectively modulating endogenous dynein activity, we show that the integrity of the dynein-dynactin motor complex is an essential requirement for both osteoclast formation and function. Systematic dissection of the osteoclast dynein-dynactin complex revealed that it is differentially localized throughout RANKL-induced osteoclast formation and activation, undergoing microtubule-coupled reorganization upon the establishment of cellular polarization. In osteoclasts actively resorbing bone, dynein-dynactin intimately co-localizes with the CAP-Gly domain-containing microtubule plus-end protein CLIP-170 at the resorptive front, thus orientating the ruffled border as a microtubule plus-end domain. Unexpectedly, disruption of the dynein-dynactin complex by exogenous p50/dynamitin expression retards osteoclast formation in vitro, owing largely to prolonged mitotic stasis of osteoclast progenitor cells. More importantly, loss of osteoclastic dynein activity results in a drastic redistribution of key intracellular organelles, including the Golgi and lysosomes, an effect that coincides with impaired cathepsin K secretion and diminished bone resorptive function. Collectively, these data unveil a previously unrecognized role for the dynein-dynactin motor complex in osteoclast formation and function, serving not only to regulate their timely maturation but also the delivery of osteolytic cargo that is essential to the bone resorptive process.
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Affiliation(s)
- Pei Ying Ng
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, WA, Australia
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22
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Yang DQ, Feng S, Chen W, Zhao H, Paulson C, Li YP. V-ATPase subunit ATP6AP1 (Ac45) regulates osteoclast differentiation, extracellular acidification, lysosomal trafficking, and protease exocytosis in osteoclast-mediated bone resorption. J Bone Miner Res 2012; 27:1695-707. [PMID: 22467241 PMCID: PMC3951719 DOI: 10.1002/jbmr.1623] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Lysosomal trafficking and protease exocytosis in osteoclasts are essential for ruffled border formation and bone resorption. Yet the mechanism underlying lysosomal trafficking and the related process of exocytosis remains largely unknown. We found ATP6ap1 (Ac45), an accessory subunit of vacuolar-type H(+)-ATPases (V-ATPases), to be highly induced by receptor activator for nuclear factor kappa B ligand (RANKL) in osteoclast differentiation. Ac45 knockdown osteoclasts formed normal actin rings, but had severely impaired extracellular acidification and bone resorption. Ac45 knockdown significantly reduced osteoclast formation. The decrease in the number of osteoclasts does not result from abnormal apoptosis; rather, it results from decreased osteoclast precursor cell proliferation and fusion, which may be partially due to the downregulation of extracellular signal-regulated kinase (ERK) phosphorylation and FBJ osteosarcoma oncogene (c-fos), nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), and "transmembrane 7 superfamily member 4" (Tm7sf4) expression. Notably, Ac45 knockdown osteoclasts exhibited impaired lysosomal trafficking and exocytosis, as indicated by the absence of lysosomal trafficking to the ruffled border and a lack of cathepsin K exocytosis into the resorption lacuna. Our data revealed that the impaired exocytosis is specifically due to Ac45 deficiency, and not the general consequence of a defective V-ATPase. Together, our results demonstrate the essential role of Ac45 in osteoclast-mediated extracellular acidification and protease exocytosis, as well as the ability of Ac45 to guide lysosomal intracellular trafficking to the ruffled border, potentially through its interaction with the small guanosine-5'-triphosphatase (GTPase) Rab7. Our work indicates that Ac45 may be a novel therapeutic target for osteolytic disease.
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Affiliation(s)
- De-Qin Yang
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
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23
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Knight AJ, Johnson NM, Behm CA. VHA-19 is essential in Caenorhabditis elegans oocytes for embryogenesis and is involved in trafficking in oocytes. PLoS One 2012; 7:e40317. [PMID: 22768351 PMCID: PMC3388054 DOI: 10.1371/journal.pone.0040317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 06/04/2012] [Indexed: 11/18/2022] Open
Abstract
There is an urgent need to develop new drugs against parasitic nematodes, which are a significant burden on human health and agriculture. Information about the function of essential nematode-specific genes provides insight to key nematode-specific processes that could be targeted with drugs. We have characterized the function of a novel, nematode-specific Caenorhabditis elegans protein, VHA-19, and show that VHA-19 is essential in the germline and, specifically, the oocytes, for the completion of embryogenesis. VHA-19 is also involved in trafficking the oocyte receptor RME-2 to the oocyte plasma membrane and is essential for osmoregulation in the embryo, probably because VHA-19 is required for proper eggshell formation via exocytosis of cortical granules or other essential components of the eggshell. VHA-19 may also have a role in cytokinesis, either directly or as an indirect effect of its role in osmoregulation. Critically, VHA-19 is expressed in the excretory cell in both larvae and adults, suggesting that it may have a role in osmoregulation in C. elegans more generally, probably in trafficking or secretion pathways. This is the first time a role for VHA-19 has been described.
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Affiliation(s)
- Alison J. Knight
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Nicholas M. Johnson
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Carolyn A. Behm
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail:
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24
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Jansen EJR, van Bakel NHM, Olde Loohuis NFM, Hafmans TGM, Arentsen T, Coenen AJM, Scheenen WJJM, Martens GJM. Identification of domains within the V-ATPase accessory subunit Ac45 involved in V-ATPase transport and Ca2+-dependent exocytosis. J Biol Chem 2012; 287:27537-46. [PMID: 22736765 DOI: 10.1074/jbc.m112.356105] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vacuolar (H(+))-ATPase (V-ATPase) is crucial for maintenance of the acidic microenvironment in intracellular organelles, whereas its membrane-bound V(0)-sector is involved in Ca(2+)-dependent membrane fusion. In the secretory pathway, the V-ATPase is regulated by its type I transmembrane and V(0)-associated accessory subunit Ac45. To execute its function, the intact-Ac45 protein is proteolytically processed to cleaved-Ac45 thereby releasing its N-terminal domain. Here, we searched for the functional domains within Ac45 by analyzing a set of deletion mutants close to the in vivo situation, namely in transgenic Xenopus intermediate pituitary melanotrope cells. Intact-Ac45 was poorly processed and accumulated in the endoplasmic reticulum of the transgenic melanotrope cells. In contrast, cleaved-Ac45 was efficiently transported through the secretory pathway, caused an accumulation of the V-ATPase at the plasma membrane and reduced dopaminergic inhibition of Ca(2+)-dependent peptide secretion. Surprisingly, removal of the C-tail from intact-Ac45 caused cellular phenotypes also found for cleaved-Ac45, whereas C-tail removal from cleaved-Ac45 still allowed its transport to the plasma membrane, but abolished V-ATPase recruitment into the secretory pathway and left dopaminergic inhibition of the cells unaffected. We conclude that domains located in the N- and C-terminal portions of the Ac45 protein direct its trafficking, V-ATPase recruitment and Ca(2+)-dependent-regulated exocytosis.
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Affiliation(s)
- Eric J R Jansen
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition, and Behaviour and Nijmegen Centre for Molecular Life Sciences (NCMLS), Faculty of Science, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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25
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Qin A, Cheng TS, Pavlos NJ, Lin Z, Dai KR, Zheng MH. V-ATPases in osteoclasts: structure, function and potential inhibitors of bone resorption. Int J Biochem Cell Biol 2012; 44:1422-35. [PMID: 22652318 DOI: 10.1016/j.biocel.2012.05.014] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 05/18/2012] [Accepted: 05/18/2012] [Indexed: 01/06/2023]
Abstract
The vacuolar-type H(+)-ATPase (V-ATPase) proton pump is a macromolecular complex composed of at least 14 subunits organized into two functional domains, V(1) and V(0). The complex is located on the ruffled border plasma membrane of bone-resorbing osteoclasts, mediating extracellular acidification for bone demineralization during bone resorption. Genetic studies from mice to man implicate a critical role for V-ATPase subunits in osteoclast-related diseases including osteopetrosis and osteoporosis. Thus, the V-ATPase complex is a potential molecular target for the development of novel anti-resorptive agents useful for the treatment of osteolytic diseases. Here, we review the current structure and function of V-ATPase subunits, emphasizing their exquisite roles in osteoclastic function. In addition, we compare several distinct classes of V-ATPase inhibitors with specific inhibitory effects on osteoclasts. Understanding the structure-function relationship of the osteoclast V-ATPase may lead to the development of osteoclast-specific V-ATPase inhibitors that may serve as alternative therapies for the treatment of osteolytic diseases.
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Affiliation(s)
- A Qin
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Crawley, Australia.
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26
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Prevention of wear particle-induced osteolysis by a novel V-ATPase inhibitor saliphenylhalamide through inhibition of osteoclast bone resorption. PLoS One 2012; 7:e34132. [PMID: 22509274 PMCID: PMC3324493 DOI: 10.1371/journal.pone.0034132] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 02/22/2012] [Indexed: 11/19/2022] Open
Abstract
Wear particle-induced peri-implant loosening (Aseptic prosthetic loosening) is one of the most common causes of total joint arthroplasty. It is well established that extensive bone destruction (osteolysis) by osteoclasts is responsible for wear particle-induced peri-implant loosening. Thus, inhibition of osteoclastic bone resorption should prevent wear particle induced osteolysis and may serve as a potential therapeutic avenue for prosthetic loosening. Here, we demonstrate for the first time that saliphenylhalamide, a new V-ATPase inhibitor attenuates wear particle-induced osteolysis in a mouse calvarial model. In vitro biochemical and morphological assays revealed that the inhibition of osteolysis is partially attributed to a disruption in osteoclast acidification and polarization, both a prerequisite for osteoclast bone resorption. Interestingly, the V-ATPase inhibitor also impaired osteoclast differentiation via the inhibition of RANKL-induced NF-κB and ERK signaling pathways. In conclusion, we showed that saliphenylhalamide affected multiple physiological processes including osteoclast differentiation, acidification and polarization, leading to inhibition of osteoclast bone resorption in vitro and wear particle-induced osteolysis in vivo. The results of the study provide proof that the new generation V-ATPase inhibitors, such as saliphenylhalamide, are potential anti-resorptive agents for treatment of peri-implant osteolysis.
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27
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Qin A, Cheng TS, Lin Z, Pavlos NJ, Jiang Q, Xu J, Dai KR, Zheng MH. Versatile roles of V-ATPases accessory subunit Ac45 in osteoclast formation and function. PLoS One 2011; 6:e27155. [PMID: 22087256 PMCID: PMC3210823 DOI: 10.1371/journal.pone.0027155] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 10/11/2011] [Indexed: 11/25/2022] Open
Abstract
Vacuolar-type H(+)-ATPases (V-ATPases) are macromolecular proton pumps that acidify intracellular cargos and deliver protons across the plasma membrane of a variety of specialized cells, including bone-resorbing osteoclasts. Extracellular acidification is crucial for osteoclastic bone resorption, a process that initiates the dissolution of mineralized bone matrix. While the importance of V-ATPases in osteoclastic resorptive function is well-defined, whether V-ATPases facilitate additional aspects of osteoclast function and/or formation remains largely obscure. Here we report that the V-ATPase accessory subunit Ac45 participates in both osteoclast formation and function. Using a siRNA-based approach, we show that targeted suppression of Ac45 impairs intracellular acidification and endocytosis, both are prerequisite for osteoclastic bone resorptive function in vitro. Interestingly, we find that knockdown of Ac45 also attenuates osteoclastogenesis owing to a reduced fusion capacity of osteoclastic precursor cells. Finally, in an effort to gain more detailed insights into the functional role of Ac45 in osteoclasts, we attempted to generate osteoclast-specific Ac45 conditional knockout mice using a Cathepsin K-Cre-LoxP system. Surprisingly, however, insertion of the neomycin cassette in the Ac45-Flox(Neo) mice resulted in marked disturbances in CNS development and ensuing embryonic lethality thus precluding functional assessment of Ac45 in osteoclasts and peripheral bone tissues. Based on these unexpected findings we propose that, in addition to its canonical function in V-ATPase-mediated acidification, Ac45 plays versatile roles during osteoclast formation and function.
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Affiliation(s)
- An Qin
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedics, Shanghai Jiao Tong University School of Medicine, Ninth People's Hospital, Shanghai, The People's Republic of China
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, Australia
| | - Tak S. Cheng
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, Australia
| | - Zhen Lin
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, Australia
- Division of Orthopaedic, Department of Surgery, Guangdong Academy of Medical Sciences, Guangdong General Hospital, Guangdong, The People's Republic of China
| | - Nathan J. Pavlos
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, Australia
| | - Qing Jiang
- Australian-China Joint Centre for Bone and Joint Research, Model Animal Research Centre of Nanjing University, Nanjing, The People's Republic of China
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital Affiliated to Medical School of Nanjing University, Nanjing, The People's Republic of China
| | - Jiake Xu
- School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, Australia
| | - Ke R. Dai
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedics, Shanghai Jiao Tong University School of Medicine, Ninth People's Hospital, Shanghai, The People's Republic of China
- Orthopaedic Cellular and Molecular Biology Laboratory, Institute of Health Sciences, School of Medicine, Chinese Academy of Sciences, Shanghai Jiao Tong University, Shanghai, The People's Republic of China
| | - Ming H. Zheng
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, Australia
- Australian-China Joint Centre for Bone and Joint Research, Model Animal Research Centre of Nanjing University, Nanjing, The People's Republic of China
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Abstract
AbstractThe rotary ATPase family of membrane protein complexes may have only three members, but each one plays a fundamental role in biological energy conversion. The F1Fo-ATPase (F-ATPase) couples ATP synthesis to the electrochemical membrane potential in bacteria, mitochondria and chloroplasts, while the vacuolar H+-ATPase (V-ATPase) operates as an ATP-driven proton pump in eukaryotic membranes. In different species of archaea and bacteria, the A1Ao-ATPase (A-ATPase) can function as either an ATP synthase or an ion pump. All three of these multi-subunit complexes are rotary molecular motors, sharing a fundamentally similar mechanism in which rotational movement drives the energy conversion process. By analogy to macroscopic systems, individual subunits can be assigned to rotor, axle or stator functions. Recently, three-dimensional reconstructions from electron microscopy and single particle image processing have led to a significant step forward in understanding of the overall architecture of all three forms of these complexes and have allowed the organisation of subunits within the rotor and stator parts of the motors to be more clearly mapped out. This review describes the emerging consensus regarding the organisation of the rotor and stator components of V-, A- and F-ATPases, examining core similarities that point to a common evolutionary origin, and highlighting key differences. In particular, it discusses how newly revealed variation in the complexity of the inter-domain connections may impact on the mechanics and regulation of these molecular machines.
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29
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Tctex-1, a novel interaction partner of Rab3D, is required for osteoclastic bone resorption. Mol Cell Biol 2011; 31:1551-64. [PMID: 21262767 DOI: 10.1128/mcb.00834-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vesicular transport along microtubules must be strictly regulated to sustain the unique structural and functional polarization of bone-resorbing osteoclasts. However, the molecular mechanisms bridging these vesicle-microtubule interactions remain largely obscure. Rab3D, a member of the Rab3 subfamily (Rab3A/B/C/D) of small exocytotic GTPases, represents a core component of the osteoclastic vesicle transport machinery. Here, we identify a new Rab3D-interacting partner, Tctex-1, a light chain of the cytoplasmic dynein microtubule motor complex, by a yeast two-hybrid screen. We demonstrate that Tctex-1 binds specifically to Rab3D in a GTP-dependent manner and co-occupies Rab3D-bearing vesicles in bone-resorbing osteoclasts. Furthermore, we provide evidence that Tctex-1 and Rab3D intimately associate with the dynein motor complex and microtubules in osteoclasts. Finally, targeted disruption of Tctex-1 by RNA interference significantly impairs bone resorption capacity and mislocalizes Rab3D vesicles in osteoclasts, attesting to the notion that components of the Rab3D-trafficking pathway contribute to the maintenance of osteoclastic resorptive function.
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D'Alessandro A, Zolla L, Scaloni A. The bovine milk proteome: cherishing, nourishing and fostering molecular complexity. An interactomics and functional overview. MOLECULAR BIOSYSTEMS 2010; 7:579-97. [PMID: 20877905 DOI: 10.1039/c0mb00027b] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bovine milk represents an essential source of nutrients for lactating calves and a key raw material for human food preparations. A wealth of data are present in the literature dealing with massive proteomic analyses of milk fractions and independent targeted studies on specific groups of proteins, such as caseins, globulins, hormones and cytokines. In this study, we merged data from previous investigations to compile an exhaustive list of 573 non-redundant annotated protein entries. This inventory was exploited for integrated in silico studies, including functional GO term enrichment (FatiGO/Babelomics), multiple pathway and network analyses. As expected, most of the milk proteins were grouped under pathways/networks/ontologies referring to nutrient transport, lipid metabolism and objectification of the immune system response. Notably enough, another functional family was observed as the most statistically significant one, which included proteins involved in the induction of cellular proliferation processes as well as in anatomical and haematological system development. Although the latter function for bovine milk proteins has long been postulated, studies reported so far mainly focused on a handful of molecules and missed the whole overview resulting from an integrated holistic analysis. A preliminary map of the bovine milk proteins interactome was also built up, which will be refined in future as result of the widespread use of quantitative methods in protein interaction studies and consequent reduction of false-positives within associated databases.
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Affiliation(s)
- Angelo D'Alessandro
- Department of Environmental Sciences, University of Tuscia, Largo dell'Università, SNC, 01100 Viterbo, Italy
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31
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Sihn G, Rousselle A, Vilianovitch L, Burckle C, Bader M. Physiology of the (pro)renin receptor: Wnt of change? Kidney Int 2010; 78:246-56. [DOI: 10.1038/ki.2010.151] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Vacuolar (H+)-ATPases in Caenorhabditis elegans: what can we learn about giant H+ pumps from tiny worms? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1687-95. [PMID: 20637717 DOI: 10.1016/j.bbabio.2010.07.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 07/07/2010] [Accepted: 07/09/2010] [Indexed: 02/08/2023]
Abstract
Vacuolar (H(+))-ATPases, also called V-ATPases, are ATP-driven proton pumps that are highly phylogenetically conserved. Early biochemical and cell biological studies have revealed many details of the molecular mechanism of proton pumping and of the structure of the multi-subunit membrane complex, including the stoichiometry of subunit composition. In addition, yeast and mouse genetics have broadened our understanding of the physiological consequences of defective vacuolar acidification and its related disease etiologies. Recently, phenotypic investigation of V-ATPase mutants in Caenorhabditis elegans has revealed unexpected new roles of V-ATPases in both cellular function and early development. In this review, we discuss the functions of the V-ATPases discovered in C. elegans.
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33
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Jansen EJR, van Bakel NHM, Coenen AJM, van Dooren SH, van Lith HAM, Martens GJM. An isoform of the vacuolar (H(+))-ATPase accessory subunit Ac45. Cell Mol Life Sci 2009; 67:629-40. [PMID: 19946730 PMCID: PMC2812417 DOI: 10.1007/s00018-009-0200-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 10/20/2009] [Accepted: 11/02/2009] [Indexed: 12/21/2022]
Abstract
The vacuolar (H+)-ATPase (V-ATPase) is the main regulator of intraorganellar pH and in neuroendocrine cells is controlled by its accessory subunit, Ac45. Here, we report the discovery of the first isoform of a V-ATPase accessory subunit, namely an Ac45-like protein, denoted Ac45LP. Phylogenetic analysis revealed a lineage-dependent evolutionary history: Ac45 is absent in birds, and Ac45LP is absent in placental mammals, whereas all other tetrapod species contain both genes. In contrast to Ac45, Ac45LP is not proteolytically cleaved, a prerequisite for proper Ac45 routing. Intriguingly, Xenopus Ac45LP mRNA was expressed in developing neural tissue and in neural crest cells. In adult Xenopus, Ac45 mRNA is widely expressed mostly in neuroendocrine tissues, while Ac45LP mRNA expression was found to be restricted to the kidney and the lung. This novel Ac45LP may provide additional possibilities for V-ATPase regulation during neurodevelopment as well as in kidney and lung cells.
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Affiliation(s)
- Eric J R Jansen
- Donders Institute for Brain, Cognition and Behaviour, and Nijmegen Centre for Molecular Life Sciences (NCMLS), Department of Molecular Animal Physiology, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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Feng H, Cheng T, Steer JH, Joyce DA, Pavlos NJ, Leong C, Kular J, Liu J, Feng X, Zheng MH, Xu J. Myocyte enhancer factor 2 and microphthalmia-associated transcription factor cooperate with NFATc1 to transactivate the V-ATPase d2 promoter during RANKL-induced osteoclastogenesis. J Biol Chem 2009; 284:14667-76. [PMID: 19321441 DOI: 10.1074/jbc.m901670200] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The V-ATPase d2 protein constitutes an important subunit of the V-ATPase proton pump, which regulates bone homeostasis; however, currently little is known about its transcriptional regulation. Here, in an attempt to understand regulation of the V-ATPase d2 promoter, we identified the presence of NFATc1, microphthalmia-associated transcription factor (MITF)- and myocyte enhancer factor 2 (MEF2)-binding sites within the V-ATPase d2 promoter using complementary bioinformatic analyses, chromatin immunoprecipitation, and electromobility shift assay. Intriguingly, activation of the V-ATPase d2 promoter by NFATc1 was enhanced by either MEF2 or MITF overexpression. By comparison, coexpression of MITF and MEF2 did not further enhance V-ATPase d2 promoter activity above that of expression of MITF alone. Consistent with a role in transcriptional regulation, both NFATc1 and MITF proteins translocated from the cytosol to the nucleus during RANKL-induced osteoclastogenesis, whereas MEF2 persisted in the nucleus of both osteoclasts and their mononuclear precursors. Targeted mutation of the putative NFATc1-, MITF-, or MEF2-binding sites in the V-ATPase d2 promoter impaired its transcriptional activation. Additionally retroviral overexpression of MITF or MEF2 in RAW264.7 cells potentiated RANKL-induced osteoclastogenesis and V-ATPase d2 gene expression. Based on these data, we propose that MEF2 and MITF function cooperatively with NFATc1 to transactivate the V-ATPase d2 promoter during RANKL-induced osteoclastogenesis.
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Affiliation(s)
- HaoTian Feng
- Centre for Orthopaedic Research, School of Surgery, University of Western Australia, Australia
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Navarro RE, Ramos-Balderas JL, Guerrero I, Pelcastre V, Maldonado E. Pigment dilution mutants from fish models with connection to lysosome-related organelles and vesicular traffic genes. Zebrafish 2009; 5:309-18. [PMID: 19133829 DOI: 10.1089/zeb.2008.0549] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An interesting question in developmental biology is why mutations in genes with functions essential for the majority of cells produce diseases affecting only specific tissues. For example, pigment dilution disorders are often the consequence of mutations in conserved vesicular traffic genes. In Hermansky-Pudlak, Griscelli, and Chediak-Higashi pigment dilution syndromes, vesicular traffic mutations affect several organs with one characteristic in common: to carry out their functions they depend to a great extent on lysosome-related organelles (LROs), such as the melanosomes in melanocytes. Conserved multimeric complexes, present in most cell types, target proteins to lysosomes or selected LROs using transport vesicles. By studying these diseases or the model organisms that are defective in these processes, we have learned that every cell type possesses a unique way to regulate its vesicular traffic machinery and to assemble its multimeric complexes. This is accomplished by subunits from these multimeric complexes acting in a cell-specific manner. Here, we review several fish pigment dilution mutants that represent models for human vesicular traffic diseases.
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Affiliation(s)
- Rosa E Navarro
- Departamento de Biología Celular, Instituto de Fisiología Celular , Universidad Nacional Autónoma de México, UNAM, México City, México
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Muench SP, Huss M, Song CF, Phillips C, Wieczorek H, Trinick J, Harrison MA. Cryo-electron Microscopy of the Vacuolar ATPase Motor Reveals its Mechanical and Regulatory Complexity. J Mol Biol 2009; 386:989-99. [DOI: 10.1016/j.jmb.2009.01.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jansen EJR, Scheenen WJJM, Hafmans TGM, Martens GJM. Accessory subunit Ac45 controls the V-ATPase in the regulated secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2301-10. [PMID: 18657579 DOI: 10.1016/j.bbamcr.2008.06.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 06/26/2008] [Accepted: 06/26/2008] [Indexed: 10/21/2022]
Abstract
The vacuolar (H(+))-ATPase (V-ATPase) is crucial for multiple processes within the eukaryotic cell, including membrane transport and neurotransmitter secretion. How the V-ATPase is regulated, e.g. by an accessory subunit, remains elusive. Here we explored the role of the neuroendocrine V-ATPase accessory subunit Ac45 via its transgenic expression specifically in the Xenopus intermediate pituitary melanotrope cell model. The Ac45-transgene product did not affect the levels of the prohormone proopiomelanocortin nor of V-ATPase subunits, but rather caused an accumulation of the V-ATPase at the plasma membrane. Furthermore, a higher abundance of secretory granules, protrusions of the plasma membrane and an increased Ca(2+)-dependent secretion efficiency were observed in the Ac45-transgenic cells. We conclude that in neuroendocrine cells Ac45 guides the V-ATPase through the secretory pathway, thereby regulating the V-ATPase-mediated process of Ca(2+)-dependent peptide secretion.
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Affiliation(s)
- Eric J R Jansen
- Department of Molecular Animal Physiology, Donders Centre for Neuroscience, Faculty of Science, Radboud University, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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