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Satarker S, Bojja SL, Gurram PC, Mudgal J, Arora D, Nampoothiri M. Astrocytic Glutamatergic Transmission and Its Implications in Neurodegenerative Disorders. Cells 2022; 11:cells11071139. [PMID: 35406702 PMCID: PMC8997779 DOI: 10.3390/cells11071139] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/12/2022] [Accepted: 03/13/2022] [Indexed: 12/11/2022] Open
Abstract
Several neurodegenerative disorders involve impaired neurotransmission, and glutamatergic neurotransmission sets a prototypical example. Glutamate is a predominant excitatory neurotransmitter where the astrocytes play a pivotal role in maintaining the extracellular levels through release and uptake mechanisms. Astrocytes modulate calcium-mediated excitability and release several neurotransmitters and neuromodulators, including glutamate, and significantly modulate neurotransmission. Accumulating evidence supports the concept of excitotoxicity caused by astrocytic glutamatergic release in pathological conditions. Thus, the current review highlights different vesicular and non-vesicular mechanisms of astrocytic glutamate release and their implication in neurodegenerative diseases. As in presynaptic neurons, the vesicular release of astrocytic glutamate is also primarily meditated by calcium-mediated exocytosis. V-ATPase is crucial in the acidification and maintenance of the gradient that facilitates the vesicular storage of glutamate. Along with these, several other components, such as cystine/glutamate antiporter, hemichannels, BEST-1, TREK-1, purinergic receptors and so forth, also contribute to glutamate release under physiological and pathological conditions. Events of hampered glutamate uptake could promote inflamed astrocytes to trigger repetitive release of glutamate. This could be favorable towards the development and worsening of neurodegenerative diseases. Therefore, across neurodegenerative diseases, we review the relations between defective glutamatergic signaling and astrocytic vesicular and non-vesicular events in glutamate homeostasis. The optimum regulation of astrocytic glutamatergic transmission could pave the way for the management of these diseases and add to their therapeutic value.
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Affiliation(s)
- Sairaj Satarker
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Sree Lalitha Bojja
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Prasada Chowdari Gurram
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Jayesh Mudgal
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Devinder Arora
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Madhavan Nampoothiri
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- Correspondence:
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Knockdown of Vacuolar ATPase Subunit G Gene Affects Larval Survival and Impaired Pupation and Adult Emergence in Henosepilachna vigintioctopunctata. INSECTS 2021; 12:insects12100935. [PMID: 34680704 PMCID: PMC8538789 DOI: 10.3390/insects12100935] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 09/30/2021] [Accepted: 10/03/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary Vacuolar ATPase (vATPase), a proton pump driven by ATP hydrolysis, acts as a membrane energizer to motivate the movement of ions and nutrients across the cellular membrane in insect guts and Malpighian tubules, among others. The vATPase holoenzyme contains 16 subunits. Out of these subunits, mammalian G subunit includes three isoforms (G1-G3) which are encoded by three distinctive genes. The physiological role of a specific G isoform can be compensated by others. Thus, current experimental evidence on the in vivo function of G is rather limited among eight V1 subunits. In the present paper, particular attention was paid to an insect model, Henosepilachna vigintioctopunctata ladybird, a serious defoliator of Solanaceae and Cucurbitaceae plants in many Asian countries. Given that the beetle is sensitive to RNA interference (RNAi), HvvATPaseG gene was knocked down by ingestion of its corresponding dsRNA at the fourth-instar larval stage. Silence of HvvATPaseG affected larval growth and survival, impaired pupation and adult emergence. Our results provide a basis for further functional research on the vATPase G subunit in insects and suggest new ideas for the management of H. vigintioctopunctata. Abstract The vATPase holoenzyme consists of two functional subcomplexes, the cytoplasmic (peripheral) V1 and the membrane-embedded V0. Both V1 and V0 sectors contain eight subunits, with stoichiometry of A3B3CDE3FG3H in V1 and ac8c’c”def(Voa1p) in V0 respectively. However, the function of G subunit has not been characterized in any non-Drosophilid insect species. In the present paper, we uncovered that HvvATPaseG was actively transcribed from embryo to adult in a Coleopteran pest Henosepilachna vigintioctopunctata. Its mRNA levels peaked in larval hindgut and Malpighian tubules. RNA interference (RNAi)-mediated knockdown of HvvATPaseG significantly reduced larval feeding, affected chitin biosynthesis, destroyed midgut integrity, damaged midgut peritrophic membrane, and retarded larval growth. The function of Malpighian tubules was damaged, the contents of glucose, trehalose, lipid, total soluble amino acids and protein were lowered and the fat bodies were lessened in the HvvATPaseG RNAi larvae, compared with those in the PBS- and dsegfp-fed beetles. In contrast, the amount of glycogen was dramatically increased in the HvvATPaseG depletion ladybirds. As a result, the development was arrested, pupation was inhibited and adult emergence was impaired in the HvvATPaseG hypomorphs. Our results demonstrated that G subunit plays a critical role during larval development in H. vigintioctopunctata.
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Jiang LH, Mu LL, Jin L, Anjum AA, Li GQ. RNAi for chitin synthase 1 rather than 2 causes growth delay and molting defect in Henosepilachna vigintioctopunctata. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 178:104934. [PMID: 34446203 DOI: 10.1016/j.pestbp.2021.104934] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/16/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Chitin synthase (CHS) plays a critical role in chitin synthesis and excretion. In most insects, CHSs have been segregated into 1 and 2 classes. CHS1 is responsible for chitin production in the ectodermally-derived epidermal cells. CHS2 is dedicated to chitin biosynthesis in the midgut peritrophic matrix (PM). Henosepilachna vigintioctopunctata is a serious pest of Solanaceae and Cucurbitaceae plants. In this study, we identified HvCHS1 and HvCHS2. We found that HvCHS1 was abundantly transcribed in the larval tracheae and epidermis, whereas HvCHS2 was mainly expressed in the guts. Escherichia coli HT115 expressed double stranded RNAs targeting HvCHS1 and HvCHS2 (dsCHS1 and dsCHS2) were used to immerse potato foliage and the treated leaves were provided to the newly-molted fourth- and third-instar larvae. Ingestion of dsCHS1 by the fourth-instar larvae significantly diminished the target mRNA level and had slight influence on the expression of HvCHS2. In contrast, consumption of dsCHS2 significantly lowered the target mRNA level but triggered the transcription of HvCHS1. Knockdown of HvCHS1, rather than HvCHS2, arrested larval development and impaired larva-pupa-adult transition. A large proportion of HvCHS1 hypomorphs became stunting prepupae, deformed pupae or misshapen adults. Moreover, knockdown of HvCHS1 damaged gut integrity, decreased cuticle thickness, and delayed the formation of newly-generated cuticle layer during ecdysis. Furthermore, depletion of HvCHS1 inhibited the development of trachea system and thinned tracheal taenidia. Ingestion of dsCHS1 at the third-instar stage caused similar but severe negative effects. Our results demonstrated that HvCHS1 is responsible for chitin biosynthesis during ecdysis. Moreover, HvCHS1 is a potential amenable target gene and young larvae are more susceptible to dsRNA.
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Affiliation(s)
- Lin-Hong Jiang
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Li-Li Mu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Lin Jin
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Ahmad Ali Anjum
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Guo-Qing Li
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
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Genetic architecture and phenotypic landscape of deafness and onychodystrophy syndromes. Hum Genet 2021; 141:821-838. [PMID: 34232384 DOI: 10.1007/s00439-021-02310-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Deafness and onychodystrophy syndromes are a group of phenotypically overlapping syndromes, which include DDOD syndrome (dominant deafness-onychodystrophy), DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation and seizures) and Zimmermann-Laband syndrome (gingival hypertrophy, coarse facial features, hypoplasia or aplasia of nails and terminal phalanges, intellectual disability, and hypertrichosis). Pathogenic variants in four genes, ATP6V1B2, TBC1D24, KCNH1 and KCNN3, have been shown to be associated with deafness and onychodystrophy syndromes. ATP6V1B2 encodes a component of the vacuolar H+-ATPase (V-ATPase) and TBC1D24 belongs to GTPase-activating protein, which are all involved in the regulation of membrane trafficking. The overlapping clinical phenotype of TBC1D24- and ATP6V1B2- related diseases and their function with GTPases or ATPases activity indicate that they may have some physiological link. Variants in genes encoding potassium channels KCNH1 or KCNN3, underlying human Zimmermann-Laband syndrome, have only recently been recognized. Although further analysis will be needed, these findings will help to elucidate an understanding of the pathogenesis of these disorders better and will aid in the development of potential therapeutic approaches. In this review, we summarize the latest developments of clinical features and molecular basis that have been reported to be associated with deafness and onychodystrophy disorders and highlight the challenges that may arise in the differential diagnosis.
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Santos-Pereira C, Rodrigues LR, Côrte-Real M. Emerging insights on the role of V-ATPase in human diseases: Therapeutic challenges and opportunities. Med Res Rev 2021; 41:1927-1964. [PMID: 33483985 DOI: 10.1002/med.21782] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/05/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022]
Abstract
The control of the intracellular pH is vital for the survival of all organisms. Membrane transporters, both at the plasma and intracellular membranes, are key players in maintaining a finely tuned pH balance between intra- and extracellular spaces, and therefore in cellular homeostasis. V-ATPase is a housekeeping ATP-driven proton pump highly conserved among prokaryotes and eukaryotes. This proton pump, which exhibits a complex multisubunit structure based on cell type-specific isoforms, is essential for pH regulation and for a multitude of ubiquitous and specialized functions. Thus, it is not surprising that V-ATPase aberrant overexpression, mislocalization, and mutations in V-ATPase subunit-encoding genes have been associated with several human diseases. However, the ubiquitous expression of this transporter and the high toxicity driven by its off-target inhibition, renders V-ATPase-directed therapies very challenging and increases the need for selective strategies. Here we review emerging evidence linking V-ATPase and both inherited and acquired human diseases, explore the therapeutic challenges and opportunities envisaged from recent data, and advance future research avenues. We highlight the importance of V-ATPases with unique subunit isoform molecular signatures and disease-associated isoforms to design selective V-ATPase-directed therapies. We also discuss the rational design of drug development pipelines and cutting-edge methodological approaches toward V-ATPase-centered drug discovery. Diseases like cancer, osteoporosis, and even fungal infections can benefit from V-ATPase-directed therapies.
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Affiliation(s)
- Cátia Santos-Pereira
- Department of Biology, Centre of Molecular and Environmental Biology (CBMA), University of Minho, Braga, Portugal.,Department of Biological Engineering, Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
| | - Lígia R Rodrigues
- Department of Biological Engineering, Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
| | - Manuela Côrte-Real
- Department of Biology, Centre of Molecular and Environmental Biology (CBMA), University of Minho, Braga, Portugal
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Song Q, Meng B, Xu H, Mao Z. The emerging roles of vacuolar-type ATPase-dependent Lysosomal acidification in neurodegenerative diseases. Transl Neurodegener 2020; 9:17. [PMID: 32393395 PMCID: PMC7212675 DOI: 10.1186/s40035-020-00196-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 04/23/2020] [Indexed: 12/15/2022] Open
Abstract
Background Lysosomes digest extracellular material from the endocytic pathway and intracellular material from the autophagic pathway. This process is performed by the resident hydrolytic enzymes activated by the highly acidic pH within the lysosomal lumen. Lysosome pH gradients are mainly maintained by the vacuolar (H+) ATPase (or V-ATPase), which pumps protons into lysosomal lumen by consuming ATP. Dysfunction of V-ATPase affects lysosomal acidification, which disrupts the clearance of substrates and leads to many disorders, including neurodegenerative diseases. Main body As a large multi-subunit complex, the V-ATPase is composed of an integral membrane V0 domain involved in proton translocation and a peripheral V1 domain catalyzing ATP hydrolysis. The canonical functions of V-ATPase rely on its H+-pumping ability in multiple vesicle organelles to regulate endocytic traffic, protein processing and degradation, synaptic vesicle loading, and coupled transport. The other non-canonical effects of the V-ATPase that are not readily attributable to its proton-pumping activity include membrane fusion, pH sensing, amino-acid-induced activation of mTORC1, and scaffolding for protein-protein interaction. In response to various stimuli, V-ATPase complex can reversibly dissociate into V1 and V0 domains and thus close ATP-dependent proton transport. Dysregulation of pH and lysosomal dysfunction have been linked to many human diseases, including neurodegenerative disorders such as Alzheimer disease, Parkinson’s disease, amyotrophic lateral sclerosis as well as neurodegenerative lysosomal storage disorders. Conclusion V-ATPase complex is a universal proton pump and plays an important role in lysosome acidification in all types of cells. Since V-ATPase dysfunction contributes to the pathogenesis of multiple neurodegenerative diseases, further understanding the mechanisms that regulate the canonical and non-canonical functions of V-ATPase will reveal molecular details of disease process and help assess V-ATPase or molecules related to its regulation as therapeutic targets.
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Affiliation(s)
- Qiaoyun Song
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Reproductive Genetics, Hebei General Hospital, Shijiazhuang, Hebei Province, 050051, People's Republic of China.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Bo Meng
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Haidong Xu
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Zixu Mao
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA. .,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
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Abbas YM, Wu D, Bueler SA, Robinson CV, Rubinstein JL. Structure of V-ATPase from the mammalian brain. Science 2020; 367:1240-1246. [PMID: 32165585 DOI: 10.1126/science.aaz2924] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/12/2020] [Indexed: 12/16/2022]
Abstract
In neurons, the loading of neurotransmitters into synaptic vesicles uses energy from proton-pumping vesicular- or vacuolar-type adenosine triphosphatases (V-ATPases). These membrane protein complexes possess numerous subunit isoforms, which complicates their analysis. We isolated homogeneous rat brain V-ATPase through its interaction with SidK, a Legionella pneumophila effector protein. Cryo-electron microscopy allowed the construction of an atomic model, defining the enzyme's ATP:proton ratio as 3:10 and revealing a homolog of yeast subunit f in the membrane region, which we tentatively identify as RNAseK. The c ring encloses the transmembrane anchors for cleaved ATP6AP1/Ac45 and ATP6AP2/PRR, the latter of which is the (pro)renin receptor that, in other contexts, is involved in both Wnt signaling and the renin-angiotensin system that regulates blood pressure. This structure shows how ATP6AP1/Ac45 and ATP6AP2/PRR enable assembly of the enzyme's catalytic and membrane regions.
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Affiliation(s)
- Yazan M Abbas
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Di Wu
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada. .,Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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Zhao W, Gao X, Qiu S, Gao B, Gao S, Zhang X, Kang D, Han W, Dai P, Yuan Y. A subunit of V-ATPases, ATP6V1B2, underlies the pathology of intellectual disability. EBioMedicine 2019; 45:408-421. [PMID: 31257146 PMCID: PMC6642280 DOI: 10.1016/j.ebiom.2019.06.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/06/2019] [Accepted: 06/18/2019] [Indexed: 01/21/2023] Open
Abstract
Background Dominant deafness-onychodystrophy (DDOD) syndrome is a rare disorder mainly characterized by severe deafness, onychodystrophy and brachydactyly. We previously identified c.1516C > T (p.Arg506X) in ATP6V1B2 as cause of DDOD syndrome, accounting for all cases of this genetic disorder. Clinical follow-up of DDOD syndrome patients with cochlear implantation revealed the language rehabilitation was unsatisfactory although the implanted cochlea worked well, which indicates there might be learning and memory problems in DDOD syndrome patients. However, the underlying mechanisms were unknown. Methods atp6v1b2 knockdown zebrafish and Atp6v1b2 c.1516C > T knockin mice were constructed to explore the phenotypes and related mechanism. In mutant mice, auditory brainstem response test and cochlear morphology analysis were performed to evaluate the auditory function. Behavioral tests were used to investigate various behavioral and cognitive domains. Resting-state functional magnetic resonance imaging was used to evaluate functional connectivity in the mouse brain. Immunofluorescence, Western blot, and co-immunoprecipitation were performed to examine the expression and interactions between the subunits of V-ATPases. Findings atp6v1b2 knockdown zebrafish showed developmental defects in multiple organs and systems. However, Atp6v1b2 c.1516C > T knockin mice displayed obvious cognitive defects but normal hearing and cochlear morphology. Impaired hippocampal CA1 region and weaker interaction between the V1E and B2 subunits in Atp6v1b2Arg506X//Arg506X mice were observed. Interpretation Our study extends the phenotypic range of DDOD syndrome. The impaired hippocampal CA1 region may be the pathological basis of the behavioral defects in mutant mice. The molecular mechanism underlying V-ATPases dysfunction involves a weak interaction between subunits, although the assembly of V-ATPases can still take place.
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Affiliation(s)
- Weihao Zhao
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China; Department of Otolaryngology General Hospital of Tibet Military Region, Lhasa 850007, China
| | - Xue Gao
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China; Department of Otolaryngology, PLA Rocket Force Characteristic Medical Center, 16# XinWai Da Jie, Beijing 100088, China
| | - Shiwei Qiu
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China
| | - Bo Gao
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China
| | - Song Gao
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China
| | - Xin Zhang
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China
| | - Dongyang Kang
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China
| | - Weiju Han
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China.
| | - Pu Dai
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China.
| | - Yongyi Yuan
- Department of Otolaryngology, Head and Neck Surgery, Chinese PLA General Hospital, 28# Fuxing Road, Beijing 100853, China.
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Bodzęta A, Kahms M, Klingauf J. The Presynaptic v-ATPase Reversibly Disassembles and Thereby Modulates Exocytosis but Is Not Part of the Fusion Machinery. Cell Rep 2017; 20:1348-1359. [DOI: 10.1016/j.celrep.2017.07.040] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/23/2017] [Accepted: 07/14/2017] [Indexed: 11/15/2022] Open
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Kang HT, Park JT, Choi K, Kim Y, Choi HJC, Jung CW, Lee YS, Park SC. Chemical screening identifies ATM as a target for alleviating senescence. Nat Chem Biol 2017; 13:616-623. [DOI: 10.1038/nchembio.2342] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 12/21/2016] [Indexed: 12/19/2022]
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Xu Z, Zhao Y, Ge Y, Peng J, Dong M, Yang G. Characterization of a vacuolar H +-ATPase G subunit gene from Juglans regia (JrVHAG1) involved in mannitol-induced osmotic stress tolerance. PLANT CELL REPORTS 2017; 36:407-418. [PMID: 27986993 DOI: 10.1007/s00299-016-2090-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 11/30/2016] [Indexed: 05/11/2023]
Abstract
JrVHAG1 is an important candidate gene for plant osmotic tolerance regulation. Vacuolar H+-ATPase (V-ATPase) is important for plant responses to abiotic stress; the G subunit is a vital part of V-ATPase. In this study, a G subunit of V-ATPase was cloned from Juglans regia (JrVHAG1) and functionally characterized. JrVHAG1 transcription was induced by mannitol that increasing 17.88-fold in the root at 12 h and 19.16-fold in the leaf at 96 h compared to that under control conditions. JrVHAG1 was overexpressed in Arabidopsis and three lines (G2, G6, and G9) with highest expression levels were selected for analysis. The results showed that under normal conditions, the transgenic and wild-type (WT) plants displayed similar germination, biomass accumulation, reactive oxygen species (ROS) level, and physiological index. However, when treated with mannitol, the fresh weight, root length, water-holding ability, and V-ATPase, superoxide dismutase, and peroxidase activity of G2, G6, and G9 were significantly higher than those of WT. In contrast, the ROS and cell damage levels of the transgenic seedlings were lower than those of WT. Furthermore, the transcription levels of V-ATPase subunits, ABF, DREB, and NAC transcription factors (TFs), all of which are factors of ABA signaling pathway, were much higher in JrVHAG1 transgenic plants than those in WT. The positive induction of JrVHAG1 gene under abscisic acid (ABA) treatments in root and leaf tissues indicates that overexpression of JrVHAG1 improves plant tolerance to osmotic stress relating to the ABA signaling pathway, which is transcriptionally activated by ABF, DREB, and NAC TFs, and correlated to ROS scavenging and V-ATPase activity.
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Affiliation(s)
- Zhenggang Xu
- College of Life Science and Technology, Central South University of Forestry and Technology, 498 Shaoshan South Road, Changsha, 410004, Hunan, China
- College of Chemistry and Environment Engineering, Hunan City University, 518 Yingbin Road, Yiyang, 413000, Hunan, China
| | - Yunlin Zhao
- College of Life Science and Technology, Central South University of Forestry and Technology, 498 Shaoshan South Road, Changsha, 410004, Hunan, China
| | - Yu Ge
- College of Forestry, Hubei University for Nationalities, 39 Xueyuan Road, Enshi, 445000, Hubei, China
| | - Jiao Peng
- College of Life Science and Technology, Central South University of Forestry and Technology, 498 Shaoshan South Road, Changsha, 410004, Hunan, China
| | - Meng Dong
- College of Chemistry and Environment Engineering, Hunan City University, 518 Yingbin Road, Yiyang, 413000, Hunan, China
| | - Guiyan Yang
- Laboratory of Walnut Research Center, College of Forestry, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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Salameh AI, Hübner CA, Boron WF. Role of Cl - -HCO 3- exchanger AE3 in intracellular pH homeostasis in cultured murine hippocampal neurons, and in crosstalk to adjacent astrocytes. J Physiol 2016; 595:93-124. [PMID: 27353306 DOI: 10.1113/jp272470] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 06/20/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS A polymorphism of human AE3 is associated with idiopathic generalized epilepsy. Knockout of AE3 in mice lowers the threshold for triggering epileptic seizures. The explanations for these effects are elusive. Comparisons of cells from wild-type vs. AE3-/- mice show that AE3 (present in hippocampal neurons, not astrocytes; mediates HCO3- efflux) enhances intracellular pH (pHi ) recovery (decrease) from alkali loads in neurons and, surprisingly, adjacent astrocytes. During metabolic acidosis (MAc), AE3 speeds initial acidification, but limits the extent of pHi decrease in neurons and astrocytes. AE3 speeds re-alkalization after removal of MAc in neurons and astrocytes, and speeds neuronal pHi recovery from an ammonium prepulse-induced acid load. We propose that neuronal AE3 indirectly increases acid extrusion in (a) neurons via Cl- loading, and (b) astrocytes by somehow enhancing NBCe1 (major acid extruder). The latter would enhance depolarization-induced alkalinization of astrocytes, and extracellular acidification, and thereby reduce susceptibility to epileptic seizures. ABSTRACT The anion exchanger AE3, expressed in hippocampal (HC) neurons but not astrocytes, contributes to intracellular pH (pHi ) regulation by facilitating the exchange of extracellular Cl- for intracellular HCO3- . The human AE3 polymorphism A867D is associated with idiopathic generalized epilepsy. Moreover, AE3 knockout (AE3-/- ) mice are more susceptible to epileptic seizure. The mechanism of these effects has been unclear because the starting pHi in AE3-/- and wild-type neurons is indistinguishable. The purpose of the present study was to use AE3-/- mice to investigate the role of AE3 in pHi homeostasis in HC neurons, co-cultured with astrocytes. We find that the presence of AE3 increases the acidification rate constant during pHi recovery from intracellular alkaline loads imposed by reducing [CO2 ]. The presence of AE3 also speeds intracellular acidification during the early phase of metabolic acidosis (MAc), not just in neurons but, surprisingly, in adjacent astrocytes. Additionally, AE3 contributes to braking the decrease in pHi later during MAc in both neurons and astrocytes. Paradoxically, AE3 enhances intracellular re-alkalization after MAc removal in neurons and astrocytes, and pHi recovery from an ammonium prepulse-induced acid load in neurons. The effects of AE3 knockout on astrocytic pHi homeostasis in MAc-related assays require the presence of neurons, and are consistent with the hypothesis that the AE3 knockout reduces functional expression of astrocytic NBCe1. These findings suggest a new type of neuron-astrocyte communication, based on the expression of AE3 in neurons, which could explain how AE3 reduces seizure susceptibility.
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Affiliation(s)
- Ahlam I Salameh
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | | | - Walter F Boron
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
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Di Cristofori A, Ferrero S, Bertolini I, Gaudioso G, Russo MV, Berno V, Vanini M, Locatelli M, Zavanone M, Rampini P, Vaccari T, Caroli M, Vaira V. The vacuolar H+ ATPase is a novel therapeutic target for glioblastoma. Oncotarget 2016; 6:17514-31. [PMID: 26020805 PMCID: PMC4627325 DOI: 10.18632/oncotarget.4239] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/02/2015] [Indexed: 01/01/2023] Open
Abstract
The vacuolar H+ ATPase (V-ATPase) is a proton pump responsible for acidification of cellular microenvironments, an activity exploited by tumors to survive, proliferate and resist to therapy. Despite few observations, the role of V-ATPase in human tumorigenesis remains unclear. We investigated the expression of ATP6V0C, ATP6V0A2, encoding two subunits belonging to the V-ATPase V0 sector and ATP6V1C, ATP6V1G1, ATPT6V1G2, ATP6V1G3, which are part of the V1 sector, in series of adult gliomas and in cancer stem cell-enriched neurospheres isolated from glioblastoma (GBM) patients. ATP6V1G1 expression resulted significantly upregulated in tissues of patients with GBM and correlated with shorter patients' overall survival independent of clinical variables. ATP6V1G1 knockdown in GBM neurospheres hampered sphere-forming ability, induced cell death, and decreased matrix invasion, a phenotype not observed in GBM monolayer cultures. Treating GBM organotypic cultures or neurospheres with the selective V-ATPase inhibitor bafilomycin A1 reproduced the effects of ATP6V1G1 siRNA and strongly suppressed expression of the stem cell markers Nestin, CD133 and transcription factors SALL2 and POU3F2 in neurospheres. These data point to ATP6V1G1 as a novel marker of poor prognosis in GBM patients and identify V-ATPase inhibition as an innovative therapeutic strategy for GBM.
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Affiliation(s)
- Andrea Di Cristofori
- Department of Pathophysiology and Organ Transplantation, University of Milan, Milan, Italy.,Division of Neurosurgery, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefano Ferrero
- Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.,Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy
| | - Irene Bertolini
- Department of Pathophysiology and Organ Transplantation, University of Milan, Milan, Italy.,Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Gabriella Gaudioso
- Department of Pathophysiology and Organ Transplantation, University of Milan, Milan, Italy.,Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Maria Veronica Russo
- Department of Pathophysiology and Organ Transplantation, University of Milan, Milan, Italy.,Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Valeria Berno
- Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Marco Vanini
- Surgical Pathology Unit, St. Anna Hospital, Como, Italy
| | - Marco Locatelli
- Division of Neurosurgery, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Mario Zavanone
- Department of Pathophysiology and Organ Transplantation, University of Milan, Milan, Italy.,Division of Neurosurgery, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Paolo Rampini
- Division of Neurosurgery, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Thomas Vaccari
- IFOM - The FIRC Institute of Molecular Oncology, Milan, Italy
| | - Manuela Caroli
- Division of Neurosurgery, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Valentina Vaira
- Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.,Istituto Nazionale Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
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14
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Rahman S, Yamato I, Saijo S, Mizutani K, Takamuku Y, Ishizuka-Katsura Y, Ohsawa N, Terada T, Shirouzu M, Yokoyama S, Murata T. Binding interactions of the peripheral stalk subunit isoforms from human V-ATPase. Biosci Biotechnol Biochem 2016; 80:878-90. [PMID: 26865189 DOI: 10.1080/09168451.2015.1135043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The mammalian peripheral stalk subunits of the vacuolar-type H(+)-ATPases (V-ATPases) possess several isoforms (C1, C2, E1, E2, G1, G2, G3, a1, a2, a3, and a4), which may play significant role in regulating ATPase assembly and disassembly in different tissues. To better understand the structure and function of V-ATPase, we expressed and purified several isoforms of the human V-ATPase peripheral stalk: E1G1, E1G2, E1G3, E2G1, E2G2, E2G3, C1, C2, H, a1NT, and a2NT. Here, we investigated and characterized the isoforms of the peripheral stalk region of human V-ATPase with respect to their affinity and kinetics in different combination. We found that different isoforms interacted in a similar manner with the isoforms of other subunits. The differences in binding affinities among isoforms were minor from our in vitro studies. However, such minor differences from the binding interaction among isoforms might provide valuable information for the future structural-functional studies of this holoenzyme.
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Affiliation(s)
- Suhaila Rahman
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan
| | - Ichiro Yamato
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan
| | - Shinya Saijo
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan
| | - Kenji Mizutani
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan.,b Department of Chemistry , Graduate School of Science, Chiba University , Chiba , Japan
| | - Yuuki Takamuku
- b Department of Chemistry , Graduate School of Science, Chiba University , Chiba , Japan
| | | | - Noboru Ohsawa
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan
| | - Takaho Terada
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan
| | - Mikako Shirouzu
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan
| | - Shigeyuki Yokoyama
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan.,d Department of Biophysics and Biochemistry , Graduate School of Science, The University of Tokyo , Tokyo , Japan
| | - Takeshi Murata
- b Department of Chemistry , Graduate School of Science, Chiba University , Chiba , Japan.,c RIKEN Systems and Structural Biology Center , Yokohama , Japan.,e Molecular Chirality Research Center, Chiba University , Chiba , Japan.,f JST, PRESTO , Chiba , Japan
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15
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Kawamura N, Sun-Wada GH, Wada Y. Loss of G2 subunit of vacuolar-type proton transporting ATPase leads to G1 subunit upregulation in the brain. Sci Rep 2015; 5:14027. [PMID: 26353914 PMCID: PMC4564858 DOI: 10.1038/srep14027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 08/13/2015] [Indexed: 12/21/2022] Open
Abstract
Vacuolar-type ATPase (V-ATPase) is a primary proton pump with versatile functions in various tissues. In nerve cells, V-ATPase is required for accumulation of neurotransmitters into secretory vesicles and subsequent release at the synapse. Neurons express a specific isoform (G2) of the G subunit of V-ATPase constituting the catalytic sector of the enzyme complex. Using gene targeting, we generated a mouse lacking functional G2 (G2 null), which showed no apparent disorders in architecture and behavior. In the G2-null mouse brain, a G1 subunit isoform, which is ubiquitously expressed in neuronal and non-neuronal tissues, accumulated more abundantly than in wild-type animals. This G1 upregulation was not accompanied by an increase in mRNA. These results indicate that loss of function of neuron-specific G2 isoform was compensated by an increase in levels of the G1 isoform without apparent upregulation of the G1 mRNA.
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Affiliation(s)
- Nobuyuki Kawamura
- Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kohdo, Kyotanabe, Kyoto 610-0395, Japan
| | - Ge-Hong Sun-Wada
- Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kohdo, Kyotanabe, Kyoto 610-0395, Japan
| | - Yoh Wada
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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16
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Rodrigues AM, Santos LEC, Covolan L, Hamani C, de Almeida ACG. pH during non-synaptic epileptiform activity—computational simulations. Phys Biol 2015; 12:056007. [DOI: 10.1088/1478-3975/12/5/056007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Hayashi A, Asanuma D, Kamiya M, Urano Y, Okabe S. High affinity receptor labeling based on basic leucine zipper domain peptides conjugated with pH-sensitive fluorescent dye: Visualization of AMPA-type glutamate receptor endocytosis in living neurons. Neuropharmacology 2015. [PMID: 26220312 DOI: 10.1016/j.neuropharm.2015.07.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Techniques to visualize receptor trafficking in living neurons are important, but currently available methods are limited in their labeling efficiency, specificity and reliability. Here we report a method for receptor labeling with a basic leucine zipper domain peptide (ZIP) and a binding cassette specific to ZIP. Receptors are tagged with a ZIP-binding cassette at their extracellular domain. Tagged receptors expressed in cultured cells were labeled with exogenously applied fluorescently labeled ZIP with low background and high affinity. To test if ZIP labeling is useful in monitoring endocytosis and intracellular trafficking, we next conjugated ZIP with a pH-sensitive dye RhP-M (ZIP-RhP-M). ZIP binding to its binding cassette was pH-resistant and RhP-M fluorescence dramatically increased in acidic environment. Thus AMPA-type glutamate receptors (AMPARs) labeled by ZIP-RhP-M can report receptor endocytosis and subsequent intracellular trafficking. Application of ZIP-RhP-M to cultured hippocampal neurons expressing AMPARs tagged with a ZIP-binding cassette resulted in appearance of fluorescent puncta in PSD-95-positive large spines, suggesting local endocytosis and acidification of AMPARs in individual mature spines. This spine pool of AMPARs in acidic environment was distinct from the early endosomes labeled by transferrin uptake. These results suggest that receptor labeling by ZIP-RhP-M is a useful technique for monitoring endocytosis and intracellular trafficking. This article is part of the Special Issue entitled 'Synaptopathy--from Biology to Therapy'.
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Affiliation(s)
- Ayako Hayashi
- Department of Cellular Neurobiology, Graduate School of Medicine, The University of Tokyo, Japan; CREST, JST, Japan
| | - Daisuke Asanuma
- Department of Neurobiology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Mako Kamiya
- Laboratory of Chemical Biology and Molecular Imaging, Graduate School of Medicine, The University of Tokyo, Japan
| | - Yasuteru Urano
- Laboratory of Chemical Biology and Molecular Imaging, Graduate School of Medicine, The University of Tokyo, Japan
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine, The University of Tokyo, Japan; CREST, JST, Japan.
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18
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Winden KD, Bragin A, Engel J, Geschwind DH. Molecular alterations in areas generating fast ripples in an animal model of temporal lobe epilepsy. Neurobiol Dis 2015; 78:35-44. [PMID: 25818007 DOI: 10.1016/j.nbd.2015.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 01/26/2015] [Accepted: 02/13/2015] [Indexed: 01/05/2023] Open
Abstract
The molecular basis of epileptogenesis is poorly characterized. Studies in humans and animal models have identified an electrophysiological signature that precedes the onset of epilepsy, which has been termed fast ripples (FRs) based on its frequency. Multiple lines of evidence implicate regions generating FRs in epileptogenesis, and FRs appear to demarcate the seizure onset zone, suggesting a role in ictogenesis as well. We performed gene expression analysis comparing areas of the dentate gyrus that generate FRs to those that do not generate FRs in a well-characterized rat model of epilepsy. We identified a small cohort of genes that are differentially expressed in FR versus non-FR brain tissue and used quantitative PCR to validate some of those that modulate neuronal excitability. Gene expression network analysis demonstrated conservation of gene co-expression between non-FR and FR samples, but examination of gene connectivity revealed changes that were most pronounced in the cm-40 module, which contains several genes associated with synaptic function and the differentially expressed genes Kcna4, Kcnv1, and Npy1r that are down-regulated in FRs. We then demonstrate that the genes within the cm-40 module are regulated by seizure activity and enriched for the targets of the RNA binding protein Elavl4. Our data suggest that seizure activity induces co-expression of genes associated with synaptic transmission and that this pattern is attenuated in areas displaying FRs, implicating the failure of this mechanism in the generation of FRs.
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Affiliation(s)
- Kellen D Winden
- Interdepartmental Program for Neuroscience, University of California, Los Angeles, Los Angeles, CA, USA; Program in Neurogenetics, University of California, Los Angeles, Los Angeles, CA, USA; Department of Neurology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Anatol Bragin
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA, USA; The Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jerome Engel
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA, USA; Department of Neurobiology, University of California, Los Angeles, Los Angeles, CA, USA; The Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Dan H Geschwind
- Interdepartmental Program for Neuroscience, University of California, Los Angeles, Los Angeles, CA, USA; Program in Neurogenetics, University of California, Los Angeles, Los Angeles, CA, USA; Department of Neurology, University of California, Los Angeles, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA; Department of Human Genetics, University of California, Los Angeles, Los Angeles, CA, USA.
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19
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De Luca M, Bucci C. A new V-ATPase regulatory mechanism mediated by the Rab interacting lysosomal protein (RILP). Commun Integr Biol 2014; 7:971572. [PMID: 26843904 PMCID: PMC4594554 DOI: 10.4161/cib.29616] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Progressive luminal acidification of intracellular compartments is important for their
functions. Proton transport into the organelle's lumen is mediated by vacuolar
ATPases (V-ATPases) large multi-subunit proton pumps organized into 2 domains, V0 and V1,
working together as a rotary machine. The interaction of each subunit with specific
partners plays a crucial role in controlling V-ATPase activity. Recently, we have shown
that RILP, a Rab7 effector regulating late endocytic traffic and biogenesis of
multivesicular bodies (MVBs), is a specific interactor of the V-ATPase subunit V1G1, a
fundamental component of the peripheral stalk for correct V-ATPase assembly. RILP controls
V1G1 stability and localization affecting V-ATPase assembly and function at the level of
endosomes and lysosomes. The discovery of this new regulatory mechanism for V-ATPase opens
new scenario to the comprehension of organelle's pH regulation and reveals a key role
of RILP in controlling different aspects of endosome to lysosome transport.
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Affiliation(s)
- Maria De Luca
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA); University of Salento ; Lecce, Italy
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA); University of Salento ; Lecce, Italy
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20
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De Luca M, Cogli L, Progida C, Nisi V, Pascolutti R, Sigismund S, Di Fiore PP, Bucci C. The Rab-interacting lysosomal protein (RILP) regulates vacuolar ATPase acting on the V1G1 subunit. J Cell Sci 2014; 127:2697-708. [DOI: 10.1242/jcs.142604] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
RILP is a downstream effector of the Rab7 GTPase. GTP-bound Rab7 recruits RILP on endosomal membranes and, together, they control late endocytic traffic, phagosome and autophagosome maturation and are responsible for signaling receptor degradation. We have identified, using different approaches, the V1G1 subunit of the vacuolar ATPase (V-ATPase) as a RILP interacting protein. V1G1 is a component of the peripheral stalk and it is fundamental for correct V-ATPase assembly. We established that RILP regulates the recruitment of V1G1 subunit to late endosomal/lysosomal membranes but also controls V1G1 stability. Indeed, we demonstrated that V1G1 is ubiquitinated and that RILP is responsible for proteasomal degradation of V1G1. Furthermore, we demonstrated that alterations of V1G1 expression levels impair V-ATPase activity. Thus, our data demonstrate for the first time that RILP regulates the activity of the V-ATPase through the interaction with V1G1. Given the importance of V-ATPase in several cellular processes and human diseases, these data suggest that modulation of RILP activity could be used to control V-ATPase function.
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Slc26a11 is prominently expressed in the brain and functions as a chloride channel: expression in Purkinje cells and stimulation of V H⁺-ATPase. Pflugers Arch 2013; 465:1583-97. [PMID: 23733100 DOI: 10.1007/s00424-013-1300-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/13/2013] [Accepted: 05/14/2013] [Indexed: 02/07/2023]
Abstract
SLC26A11 (human)/Slc26a11 (mouse), also known as kidney brain anion transporter (KBAT), is a member of the SLC26 anion transporter family and shows abundant mRNA expression in the brain. However, its exact cellular distribution and subcellular localization in the brain and its functional identity and possible physiological roles remain unknown. Expression and immunostaining studies demonstrated that Slc26a11 is abundantly expressed in the cerebellum, with a predominant expression in Purkinje cells. Lower expression levels were detected in hippocampus, olfactory bulb, cerebral cortex, and subcortical structures. Patch clamp studies in HEK293 cells transfected with mouse cDNA demonstrated that Slc26a11 can function as a chloride channel that is active under basal conditions and is not regulated by calcium, forskolin, or co-expression with cystic fibrosis transmembrane regulator. Single and double immunofluorescent labeling studies demonstrated the localization of vacuolar (V) H⁺-ATPase and Slc26a11 (KBAT) in the plasma membrane in Purkinje cells. Functional studies in HEK293 cells indicated that transfection with Slc26a11 stimulated acid transport via endogenous V H⁺-ATPase. We conclude that Slc26a11 (KBAT) is prominently distributed in output neurons of various subcortical and cortical structures in the central nervous system, with specific expression in Purkinje cells and that it may operate as a chloride channel regulating acid translocation by H⁺-ATPase across the plasma membrane and in intracellular compartments.
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22
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Gene expression profiles analyzed by DNA sequencing of cDNA clones constructed from porcine preadipocytes and adipocytes. Genes Genomics 2012. [DOI: 10.1007/s13258-011-0075-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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23
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Rahman S, Ishizuka-Katsura Y, Arai S, Saijo S, Yamato I, Toyama M, Ohsawa N, Inoue M, Honda K, Terada T, Shirouzu M, Yokoyama S, Iwata S, Murata T. Expression, purification and characterization of isoforms of peripheral stalk subunits of human V-ATPase. Protein Expr Purif 2011; 78:181-8. [PMID: 21356312 DOI: 10.1016/j.pep.2011.02.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 02/20/2011] [Accepted: 02/23/2011] [Indexed: 12/29/2022]
Abstract
The vacuolar-type H+-ATPase (V-ATPase) is a multi-subunit proton pump that is involved in both intra- and extracellular acidification processes throughout human body. Subunits constituting the peripheral stalk of the V-ATPase are known to have several isoforms responsible for tissue/cell specific different physiological roles. To study the different interaction of these isoforms, we expressed and purified the isoforms of human V-ATPase peripheral stalk subunits using Escherichia coli cell-free protein synthesis system: E1, E2, G1, G2, G3, C1, C2, H and N-terminal soluble part of a1 and a2 isoforms. The purification conditions were different depending on the isoforms, maybe reflecting the isoform specific biochemical characteristics. The purified proteins are expected to facilitate further experiments to study about the cell specific interaction and regulation and thus provide insight into physiological meaning of the existence of several isoforms of each subunit in V-ATPase.
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Affiliation(s)
- Suhaila Rahman
- Department of Biological Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan
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Toei M, Saum R, Forgac M. Regulation and isoform function of the V-ATPases. Biochemistry 2010; 49:4715-23. [PMID: 20450191 DOI: 10.1021/bi100397s] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The vacuolar (H(+))-ATPases are ATP-dependent proton pumps that acidify intracellular compartments and, in some cases, transport protons across the plasma membrane of eukaryotic cells. Intracellular V-ATPases play an important role in normal physiological processes such as receptor-mediated endocytosis, intracellular membrane trafficking, pro-hormone processing, protein degradation, and the coupled uptake of small molecules, such as neurotransmitters. They also function in the entry of various pathogenic agents, including many envelope viruses, like influenza virus, and toxins, like anthrax toxin. Plasma membrane V-ATPases function in renal pH homeostasis, bone resorption and sperm maturation, and various disease processes, including renal tubular acidosis, osteopetrosis, and tumor metastasis. V-ATPases are composed of a peripheral V(1) domain containing eight different subunits that is responsible for ATP hydrolysis and an integral V(0) domain containing six different subunits that translocates protons. In mammalian cells, most of the V-ATPase subunits exist in multiple isoforms which are often expressed in a tissue specific manner. Isoforms of one of the V(0) subunits (subunit a) have been shown to possess information that targets the V-ATPase to distinct cellular destinations. Mutations in isoforms of subunit a lead to the human diseases osteopetrosis and renal tubular acidosis. A number of mechanisms are employed to regulate V-ATPase activity in vivo, including reversible dissociation of the V(1) and V(0) domains, control of the tightness of coupling of proton transport and ATP hydrolysis, and selective targeting of V-ATPases to distinct cellular membranes. Isoforms of subunit a are involved in regulation both via the control of coupling and via selective targeting. This review will begin with a brief introduction to the function, structure, and mechanism of the V-ATPases followed by a discussion of the role of V-ATPase subunit isoforms and the mechanisms involved in regulation of V-ATPase activity.
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Affiliation(s)
- Masashi Toei
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Atp6v1c1 is an essential component of the osteoclast proton pump and in F-actin ring formation in osteoclasts. Biochem J 2009; 417:195-203. [PMID: 18657050 DOI: 10.1042/bj20081073] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bone resorption relies on the extracellular acidification function of V-ATPase (vacuolar-type proton-translocating ATPase) proton pump(s) present in the plasma membrane of osteoclasts. The exact configuration of the osteoclast-specific ruffled border V-ATPases remains largely unknown. In the present study, we found that the V-ATPase subunit Atp6v1c1 (C1) is highly expressed in osteoclasts, whereas subunits Atp6v1c2a (C2a) and Atp6v1c2b (C2b) are not. The expression level of C1 is highly induced by RANKL [receptor activator for NF-kappaB (nuclear factor kappaB) ligand] during osteoclast differentiation; C1 interacts with Atp6v0a3 (a3) and is mainly localized on the ruffled border of activated osteoclasts. The results of the present study show for the first time that C1-silencing by lentivirus-mediated RNA interference severely impaired osteoclast acidification activity and bone resorption, whereas cell differentiation did not appear to be affected, which is similar to a3 silencing. The F-actin (filamentous actin) ring formation was severely defected in C1-depleted osteoclasts but not in a3-depleted and a3(-/-) osteoclasts. C1 co-localized with microtubules in the plasma membrane and its vicinity in mature osteoclasts. In addition, C1 co-localized with F-actin in the cytoplasm; however, the co-localization chiefly shifted to the cell periphery of mature osteoclasts. The present study demonstrates that Atp6v1c1 is an essential component of the osteoclast proton pump at the osteoclast ruffled border and that it may regulate F-actin ring formation in osteoclast activation.
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26
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Guillard M, Dimopoulou A, Fischer B, Morava E, Lefeber DJ, Kornak U, Wevers RA. Vacuolar H+-ATPase meets glycosylation in patients with cutis laxa. Biochim Biophys Acta Mol Basis Dis 2009; 1792:903-14. [PMID: 19171192 DOI: 10.1016/j.bbadis.2008.12.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 12/22/2008] [Accepted: 12/29/2008] [Indexed: 02/08/2023]
Abstract
Glycosylation of proteins is one of the most important post-translational modifications. Defects in the glycan biosynthesis result in congenital malformation syndromes, also known as congenital disorders of glycosylation (CDG). Based on the iso-electric focusing patterns of plasma transferrin and apolipoprotein C-III a combined defect in N- and O-glycosylation was identified in patients with autosomal recessive cutis laxa type II (ARCL II). Disease-causing mutations were identified in the ATP6V0A2 gene, encoding the a2 subunit of the vacuolar H(+)-ATPase (V-ATPase). The V-ATPases are multi-subunit, ATP-dependent proton pumps located in membranes of cells and organels. In this article, we describe the structure, function and regulation of the V-ATPase and the phenotypes currently known to result from V-ATPase mutations. A clinical overview of cutis laxa syndromes is presented with a focus on ARCL II. Finally, the relationship between ATP6V0A2 mutations, the glycosylation defect and the ARCLII phenotype is discussed.
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Affiliation(s)
- Mailys Guillard
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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Jefferies KC, Cipriano DJ, Forgac M. Function, structure and regulation of the vacuolar (H+)-ATPases. Arch Biochem Biophys 2008; 476:33-42. [PMID: 18406336 PMCID: PMC2543942 DOI: 10.1016/j.abb.2008.03.025] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 03/05/2008] [Accepted: 03/07/2008] [Indexed: 02/07/2023]
Abstract
The vacuolar ATPases (or V-ATPases) are ATP-driven proton pumps that function to both acidify intracellular compartments and to transport protons across the plasma membrane. Intracellular V-ATPases function in such normal cellular processes as receptor-mediated endocytosis, intracellular membrane traffic, prohormone processing, protein degradation and neurotransmitter uptake, as well as in disease processes, including infection by influenza and other viruses and killing of cells by anthrax and diphtheria toxin. Plasma membrane V-ATPases are important in such physiological processes as urinary acidification, bone resorption and sperm maturation as well as in human diseases, including osteopetrosis, renal tubular acidosis and tumor metastasis. V-ATPases are large multi-subunit complexes composed of a peripheral domain (V(1)) responsible for hydrolysis of ATP and an integral domain (V(0)) that carries out proton transport. Proton transport is coupled to ATP hydrolysis by a rotary mechanism. V-ATPase activity is regulated in vivo using a number of mechanisms, including reversible dissociation of the V(1) and V(0) domains, changes in coupling efficiency of proton transport and ATP hydrolysis and changes in pump density through reversible fusion of V-ATPase containing vesicles. V-ATPases are emerging as potential drug targets in treating a number of human diseases including osteoporosis and cancer.
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Affiliation(s)
| | | | - Michael Forgac
- Department of Physiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111
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28
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Hayashi K, Sun-Wada GH, Wada Y, Nakanishi-Matsui M, Futai M. Defective assembly of a hybrid vacuolar H(+)-ATPase containing the mouse testis-specific E1 isoform and yeast subunits. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1370-7. [PMID: 18662668 DOI: 10.1016/j.bbabio.2008.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 06/26/2008] [Accepted: 06/30/2008] [Indexed: 01/10/2023]
Abstract
Mammalian vacuolar-type proton pumping ATPases (V-ATPases) are diverse multi-subunit proton pumps. They are formed from membrane V(o) and catalytic V(1) sectors, whose subunits have cell-specific or ubiquitous isoforms. Biochemical study of a unique V-ATPase is difficult because ones with different isoforms are present in the same cell. However, the properties of mouse isoforms can be studied using hybrid V-ATPases formed from the isoforms and other yeast subunits. As shown previously, mouse subunit E isoform E1 (testis-specific) or E2 (ubiquitous) can form active V-ATPases with other subunits of yeast, but E1/yeast hybrid V-ATPase is defective in proton transport at 37 degrees C (Sun-Wada, G.-H., Imai-Senga, Y., Yamamoto, A., Murata, Y., Hirata, T., Wada, Y., and Futai, M., 2002, J. Biol. Chem. 277, 18098-18105). In this study, we have analyzed the properties of E1/yeast hybrid V-ATPase to understand the role of the E subunit. The proton transport by the defective hybrid ATPase was reversibly recovered when incubation temperature of vacuoles or cells was shifted to 30 degrees C. Corresponding to the reversible defect of the hybrid V-ATPase, the V(o) subunit a epitope was exposed to the corresponding antibody at 37 degrees C, but became inaccessible at 30 degrees C. However, the V(1) sector was still associated with V(o) at 37 degrees C, as shown immunochemically. The control yeast V-ATPase was active at 37 degrees C, and its epitope was not accessible to the antibody. Glucose depletion, known to dissociate V(1) from V(o) in yeast, had only a slight effect on the hybrid at acidic pH. The domain between Lys26 and Val83 of E1, which contains eight residues not conserved between E1 and E2, was responsible for the unique properties of the hybrid. These results suggest that subunit E, especially its amino-terminal domain, plays a pertinent role in the assembly of V-ATPase subunits in vacuolar membranes.
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Affiliation(s)
- Kazuhiro Hayashi
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Iwate, Japan
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29
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Marshansky V, Futai M. The V-type H+-ATPase in vesicular trafficking: targeting, regulation and function. Curr Opin Cell Biol 2008; 20:415-26. [PMID: 18511251 PMCID: PMC7111286 DOI: 10.1016/j.ceb.2008.03.015] [Citation(s) in RCA: 374] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 03/27/2008] [Accepted: 03/31/2008] [Indexed: 12/31/2022]
Abstract
Vacuolar-type H+-ATPase (V-ATPase)-driven proton pumping and organellar acidification is essential for vesicular trafficking along both the exocytotic and endocytotic pathways of eukaryotic cells. Deficient function of V-ATPase and defects of vesicular acidification have been recently recognized as important mechanisms in a variety of human diseases and are emerging as potential therapeutic targets. In the past few years, significant progress has been made in our understanding of function, regulation, and the cell biological role of V-ATPase. Here, we will review these studies with emphasis on novel direct roles of V-ATPase in the regulation of vesicular trafficking events.
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Affiliation(s)
- Vladimir Marshansky
- Program in Membrane Biology, Center for Systems Biology, Simches Research Center, CPZN No. 8212, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA.
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30
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Vacuolar-type H(+)-ATPase with the a3 isoform is the proton pump on premature melanosomes. Cell Tissue Res 2008; 332:447-60. [PMID: 18408955 DOI: 10.1007/s00441-008-0597-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 01/30/2008] [Indexed: 10/22/2022]
Abstract
The melanosome, an organelle specialized for melanin synthesis, is one of the lysosome-related organelles. Its lumen is reported to be acidified by vacuolar-type H(+)-ATPase (V-ATPase). Mammalian V-ATPase exhibits structural diversity in its subunit isoforms; with regard to membrane intrinsic subunit a, four isoforms (a1-a4) have been found to be localized to distinct subcellular compartments. In this study, we have shown that the a3 isoform is co-localized with a melanosome marker protein, Pmel17, in mouse melanocytes. Acidotropic probes (LysoSensor and DAMP) accumulate in non-pigmented Pmel17-positive melanosomes, and DAMP accumulation is sensitive to bafilomycin A1, a specific inhibitor of V-ATPase. However, none of the subunit a isoforms is associated with highly pigmented mature melanosomes, in which the acidotropic probes are also not accumulated. oc/oc mice, which have a null mutation at the a3 locus, show no obvious defects in melanogenesis. In the mutant melanocytes, the expression of the a2 isoform is modestly elevated, and a considerable fraction of this isoform is localized to premature melanosomes. These observations suggest that the V-ATPase keeps the lumen of premature melanosomes acidic, whereas melanosomal acidification is less significant in mature melanosomes.
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31
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Shuba YM, Dietrich CJ, Oermann E, Cleemann L, Morad M. Local extracellular acidification caused by Ca2+-dependent exocytosis in PC12 cells. Cell Calcium 2008; 44:220-9. [PMID: 18346783 DOI: 10.1016/j.ceca.2007.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 11/06/2007] [Accepted: 12/01/2007] [Indexed: 11/26/2022]
Abstract
Exocytosis of acidic synaptic vesicles may produce local extracellular acidification, but this effect has not been measured directly and its magnitude may depend on the geometry and pH-buffering capacity of both the vesicles and the extracellular space. Here we have used SNARF dye immobilized by conjugation to dextran to measure the release of protons from PC12 cells. The PC12 cells were stimulated by exposure to depolarizing K(+)-rich solution and activation was verified by fluorescence measurement of intracellular Ca(2+) and the release kinetics of GFP-labeled vesicles. Confocal imaging of the pH-dependent fluorescence from the immobile extracellular SNARF dye showed transient acidification around the cell bodies and neurites of activated PC12 cells. The local acidification was abolished when extracellular solution was devoid of Ca(2+) or strong pH-buffering was imposed with 10mM of HEPES. We conclude that the release of secretory vesicles induces local rises in proton concentrations that are co-released from synaptic vesicles with the primary neurotransmitter, and propose that the co-released protons may modulate the signaling in confined micro-domains of synapses.
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Affiliation(s)
- Yaroslav M Shuba
- Department of Pharmacology, Georgetown University, Washington, DC 20057, USA
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32
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Abstract
The acidity of intracellular compartments and the extracellular environment is crucial to various cellular processes, including membrane trafficking, protein degradation, bone resorption and sperm maturation. At the heart of regulating acidity are the vacuolar (V-)ATPases--large, multisubunit complexes that function as ATP-driven proton pumps. Their activity is controlled by regulating the assembly of the V-ATPase complex or by the dynamic regulation of V-ATPase expression on membrane surfaces. The V-ATPases have been implicated in a number of diseases and, coupled with their complex isoform composition, represent attractive and potentially highly specific drug targets.
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Affiliation(s)
- Michael Forgac
- Department of Physiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, Massachusetts 02111, USA.
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Breton S, Brown D. New insights into the regulation of V-ATPase-dependent proton secretion. Am J Physiol Renal Physiol 2006; 292:F1-10. [PMID: 17032935 DOI: 10.1152/ajprenal.00340.2006] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The vacuolar H(+)-ATPase (V-ATPase) is a key player in several aspects of cellular function, including acidification of intracellular organelles and regulation of extracellular pH. In specialized cells of the kidney, male reproductive tract and osteoclasts, proton secretion via the V-ATPase represents a major process for the regulation of systemic acid/base status, sperm maturation and bone resorption, respectively. These processes are regulated via modulation of the plasma membrane expression and activity of the V-ATPase. The present review describes selected aspects of V-ATPase regulation, including recycling of V-ATPase-containing vesicles to and from the plasma membrane, assembly/disassembly of the two domains (V(0) and V(1)) of the holoenzyme, and the coupling ratio between ATP hydrolysis and proton pumping. Modulation of the V-ATPase-rich cell phenotype and the pathophysiology of the V-ATPase in humans and experimental animals are also discussed.
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Affiliation(s)
- Sylvie Breton
- Program in Membrane Biology, Nephrology Division, Massachusetts General Hospital, and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114-2790, USA.
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Nakanishi-Matsui M, Futai M. Stochastic proton pumping ATPases: from single molecules to diverse physiological roles. IUBMB Life 2006; 58:318-22. [PMID: 16754325 DOI: 10.1080/15216540600702255] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We discuss the most recent reports on two proton pumps, F-ATPase (ATP synthase) and V-ATPase (endomembrane proton pump). They are formed from similar extrinsic (F1 or V1) and intrinsic (Fo or Vo) membrane sectors, and couple chemistry and proton transport through subunit rotation for apparently different physiological roles. Emphasis is placed on the stochastic rotational catalysis of F-ATPase and isoforms of V-ATPase.
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Affiliation(s)
- Mayumi Nakanishi-Matsui
- Futai Special Laboratory, Microbial Chemistry Research Center, Microbial Chemistry Research Foundation, CREST, Japan Science, and Technology Agency, Kamiosaki, Shinagawa-ku, Tokyo, Japan
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35
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Sun-Wada GH, Tabata H, Kawamura N. Selective assembly of V-ATPase subunit isoforms in mouse kidney. J Bioenerg Biomembr 2006; 37:415-8. [PMID: 16691475 DOI: 10.1007/s10863-005-9482-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The kidney plays vital roles in acid-base homeostasis, and the reabsorption of water, ions, and proteins. These processes are achieved through acidification of urine and endosomes of proximal tubule epithelial cells. Multisubunit vacuolar-type proton ATPase (V-ATPase) is one of the major acidification-machinery proteins that localizes to the apical or basolateral plasma membranes of intercalated cells in collecting ducts and the endosomal region at the base of brush border microvilli in proximal tubules. Multiple subunit isoforms of V-ATPase, which are expressed in kidney, have been identified. One obvious question is whether the pumps at different locations in the kidney have their own unique subunit identities. We have used a combination of methods to study this enzyme in kidney including immunocytochemical staining and immunoprecipitation analyses. The subunit isoforms of V-ATPase exhibited selective association/assembly in kidney: kidney-specific isoforms predominantly formed the intercalated cell proton pump, whereas the pump located in the brush border comprised ubiquitously expressed counterparts.
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Affiliation(s)
- Ge-Hong Sun-Wada
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College, Kyoto, Japan.
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36
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Beyenbach KW, Wieczorek H. The V-type H+ ATPase: molecular structure and function, physiological roles and regulation. ACTA ACUST UNITED AC 2006; 209:577-89. [PMID: 16449553 DOI: 10.1242/jeb.02014] [Citation(s) in RCA: 437] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It was nearly 30 years before the V-type H+ ATPase was admitted to the small circle of bona fide transport ATPases alongside F-type and P-type ATPases. The V-type H+ ATPase is an ATP-driven enzyme that transforms the energy of ATP hydrolysis to electrochemical potential differences of protons across diverse biological membranes via the primary active transport of H+. In turn, the transmembrane electrochemical potential of H+ is used to drive a variety of (i) secondary active transport systems via H+-dependent symporters and antiporters and (ii) channel-mediated transport systems. For example, expression of Cl- channels or transporters next to the V-type H+ ATPase in vacuoles of plants and fungi and in lysosomes of animals brings about the acidification of the endosomal compartment, and the expression of the H+/neurotransmitter antiporter next to the V-type H+ ATPase concentrates neurotransmitters in synaptic vesicles. First found in association with endosomal membranes, the V-type H+ ATPase is now also found in increasing examples of plasma membranes where the proton pump energizes transport across cell membranes and entire epithelia. The molecular details reveal up to 14 protein subunits arranged in (i) a cytoplasmic V1 complex, which mediates the hydrolysis of ATP, and (ii) a membrane-embedded V0 complex, which translocates H+ across the membrane. Clever experiments have revealed the V-type H+ ATPase as a molecular motor akin to F-type ATPases. The hydrolysis of ATP turns a rotor consisting largely of one copy of subunits D and F of the V1 complex and a ring of six or more copies of subunit c of the V0 complex. The rotation of the ring is thought to deliver H+ from the cytoplasmic to the endosomal or extracellular side of the membrane, probably via channels formed by subunit a. The reversible dissociation of V1 and V0 complexes is one mechanism of physiological regulation that appears to be widely conserved from yeast to animal cells. Other mechanisms, such as subunit-subunit interactions or interactions of the V-type H+ ATPase with other proteins that serve physiological regulation, remain to be explored. Some diseases can now be attributed to genetic alterations of specific subunits of the V-type H+ ATPase.
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Affiliation(s)
- Klaus W Beyenbach
- Department of Biomedical Sciences, VRT 8004, Cornell University, Ithaca, NY 14853, USA.
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37
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Chen F, Vitry S, Hocquemiller M, Desmaris N, Ausseil J, Heard JM. alpha-L-Iduronidase transport in neurites. Mol Genet Metab 2006; 87:349-58. [PMID: 16439176 DOI: 10.1016/j.ymgme.2005.11.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 11/16/2005] [Accepted: 11/17/2005] [Indexed: 11/17/2022]
Abstract
Effective therapeutic strategies for mucopolysaccharidosis type I (MPSI) rely on mannose-6-phosphate receptor-mediated uptake of extracellular alpha-l-iduronidase (IDUA), the missing lysosomal enzyme in this disease, by deficient cells. Intravenously infused recombinant human IDUA does not reach the central nervous system, whereas neuropathology and neurological manifestations are prominent in Hurler syndrome, the most severe and most frequent form of MPSI. The creation of a single intracerebral source of IDUA by gene therapy was proved efficient to deliver enzyme throughout the brain of MPSI mice. IDUA spreading far beyond areas where the enzyme was synthesized suggested transport along neuronal processes. To examine the mechanisms of IDUA spreading in the brain, we constructed a chimeric protein in which GFP is fused at the C-terminus of IDUA. The fusion protein was expressed in rat primary neurons using lentivirus vectors. Fluorescent IDUA retained full catalytic activity including on natural substrates, interacted with mannose-6-phosphate receptors and was appropriately addressed to lysosomes. Fluorescent vesicles were broadly distributed over neuronal soma and processes. Time-lapse fluorescent video-microscopy showed that 54% of fluorescent vesicles exhibited either retrograde or anterograde displacements along neurites. Most moving organelles showed complex movements with frequent direction changes and arrests. Motility depended on microtubule integrity. Efficient axono-dendritic transport of IDUA provides a rationale for gene therapy based on the release of therapeutic enzyme at discrete locations within the central nervous system of patients with severe form of MPSI.
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Affiliation(s)
- Fengtian Chen
- Unité Rétrovirus et Transfert Génétique, INSERM U622, Institut Pasteur, Paris, France
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38
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Pietrement C, Sun-Wada GH, Silva ND, McKee M, Marshansky V, Brown D, Futai M, Breton S. Distinct expression patterns of different subunit isoforms of the V-ATPase in the rat epididymis. Biol Reprod 2005; 74:185-94. [PMID: 16192400 DOI: 10.1095/biolreprod.105.043752] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In the epididymis and vas deferens, the vacuolar H(+)ATPase (V-ATPase), located in the apical pole of narrow and clear cells, is required to establish an acidic luminal pH. Low pH is important for the maturation of sperm and their storage in a quiescent state. The V-ATPase also participates in the acidification of intracellular organelles. The V-ATPase contains many subunits, and several of these subunits have multiple isoforms. So far, only subunits ATP6V1B1, ATP6V1B2, and ATP6V1E2, previously identified as B1, B2, and E subunits, have been described in the rat epididymis. Here, we report the localization of V-ATPase subunit isoforms ATP6V1A, ATP6V1C1, ATP6V1C2, ATP6V1G1, ATP6V1G3, ATP6V0A1, ATP6V0A2, ATP6V0A4, ATP6V0D1, and ATP6V0D2, previously labeled A, C1, C2, G1, G3, a1, a2, a4, d1, and d2, in epithelial cells of the rat epididymis and vas deferens. Narrow and clear cells showed a strong apical staining for all subunits, except the ATP6V0A2 isoform. Subunits ATP6V0A2 and ATP6V1A were detected in intracellular structures closely associated but not identical to the TGN of principal cells and narrow/clear cells, and subunit ATP6V0D1 was strongly expressed in the apical membrane of principal cells in the apparent absence of other V-ATPase subunits. In conclusion, more than one isoform of subunits ATP6V1C, ATP6V1G, ATP6V0A, and ATP6V0D of the V-ATPase are present in the epididymal and vas deferens epithelium. Our results confirm that narrow and clear cells are well fit for active proton secretion. In addition, the diverse functions of the V-ATPase may be established through the utilization of specific subunit isoforms. In principal cells, the ATP6V0D1 isoform may have a physiological function that is distinct from its role in proton transport via the V-ATPase complex.
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Affiliation(s)
- C Pietrement
- Program in Membrane Biology, Massachusetts General Hospital, Boston, MA 02114, USA
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39
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Abe T, Matsumura S, Katano T, Mabuchi T, Takagi K, Xu L, Yamamoto A, Hattori K, Yagi T, Watanabe M, Nakazawa T, Yamamoto T, Mishina M, Nakai Y, Ito S. Fyn kinase-mediated phosphorylation of NMDA receptor NR2B subunit at Tyr1472 is essential for maintenance of neuropathic pain. Eur J Neurosci 2005; 22:1445-54. [PMID: 16190898 DOI: 10.1111/j.1460-9568.2005.04340.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite abundant evidence implicating the importance of N-methyl-D-aspartate (NMDA) receptors in the spinal cord for pain transmission, the signal transduction coupled to NMDA receptor activation is largely unknown for the neuropathic pain state that lasts over periods of weeks. To address this, we prepared mice with neuropathic pain by transection of spinal nerve L5. Wild-type, NR2A-deficient, and NR2D-deficient mice developed neuropathic pain; in addition, phosphorylation of NR2B subunits of NMDA receptors at Tyr1472 was observed in the superficial dorsal horn of the spinal cord 1 week after nerve injury. Neuropathic pain and NR2B phosphorylation at Tyr1472 were attenuated by the NR2B-selective antagonist CP-101,606 and disappeared in mice lacking Fyn kinase, a Src-family tyrosine kinase. Concomitant with the NR2B phosphorylation, an increase in neuronal nitric oxide synthase activity was visualized in the superficial dorsal horn of neuropathic pain mice by NADPH diaphorase histochemistry. Electron microscopy showed that the phosphorylated NR2B was localized at the postsynaptic density in the spinal cord of mice with neuropathic pain. Indomethacin, an inhibitor of prostaglandin (PG) synthesis, and PGE receptor subtype EP1-selective antagonist reduced the NR2B phosphorylation in these mice. Conversely, EP1-selective agonist stimulated Fyn kinase-dependent nitric oxide formation in the spinal cord. The present study demonstrates that Tyr1472 phosphorylation of NR2B subunits by Fyn kinase may have dual roles in the retention of NMDA receptors in the postsynaptic density and in activation of nitric oxide synthase, and suggests that PGE2 is involved in the maintenance of neuropathic pain via the EP1 subtype.
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MESH Headings
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Blotting, Western
- Dinoprostone/physiology
- Dose-Response Relationship, Drug
- Histocytochemistry
- Mice
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Knockout
- Microscopy, Immunoelectron
- Neoplasm Proteins
- Nitric Oxide/metabolism
- Pain/etiology
- Pain/physiopathology
- Pain/psychology
- Peripheral Nervous System Diseases/complications
- Phosphorylation
- Piperidines/pharmacology
- Protein-Tyrosine Kinases
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/physiology
- Signal Transduction/physiology
- Tyrosine/metabolism
- src-Family Kinases/physiology
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Affiliation(s)
- Tetsuya Abe
- Department of Medical Chemistry, Kansai Medical University, Moriguchi 570-8506, Japan
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Allan AK, Du J, Davies SA, Dow JAT. Genome-wide survey of V-ATPase genes inDrosophilareveals a conserved renal phenotype for lethal alleles. Physiol Genomics 2005; 22:128-38. [PMID: 15855386 DOI: 10.1152/physiolgenomics.00233.2004] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
V-ATPases are ubiquitous, vital proton pumps that play a multiplicity of roles in higher organisms. In many epithelia, they are the major energizer of cotransport processes and have been implicated in functions as diverse as fluid secretion and longevity. The first animal knockout of a V-ATPase was identified in Drosophila, and its recessive lethality demonstrated the essential nature of V-ATPases. This article surveys the entire V-ATPase gene family in Drosophila, both experimentally and in silico. Adult expression patterns of most of the genes are shown experimentally for the first time, using in situ hybridization or reporter gene expression, and these results are reconciled with published expression and microarray data. For each subunit, the single gene identified previously by microarray, as upregulated and abundant in tubules, is shown to be similarly abundant in other epithelia in which V-ATPases are known to be important; there thus appears to be a single dominant “plasma membrane” V-ATPase holoenzyme in Drosophila. This provides the most comprehensive view of V-ATPase expression yet in a multicellular organism. The transparent Malpighian tubule phenotype first identified in lethal alleles of vha55, the gene encoding the B-subunit, is shown to be general to those plasma membrane V-ATPase subunits for which lethal alleles are available, and to be caused by failure to accumulate uric acid crystals. These results coincide with the expression view of the gene family, in which 13 of the genes are specialized for epithelial roles, whereas others have spatially or temporally restricted patterns of expression.
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Affiliation(s)
- Adrian K Allan
- Institute of Biomedical and Life Sciences Division of Molecular Genetics, University of Glasgow, Glasgow, United Kingdom
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Owegi MA, Carenbauer AL, Wick NM, Brown JF, Terhune KL, Bilbo SA, Weaver RS, Shircliff R, Newcomb N, Parra-Belky KJ. Mutational analysis of the stator subunit E of the yeast V-ATPase. J Biol Chem 2005; 280:18393-402. [PMID: 15718227 DOI: 10.1074/jbc.m412567200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit E is a component of the peripheral stalk(s) that couples membrane and peripheral subunits of the V-ATPase complex. In order to elucidate the function of subunit E, site-directed mutations were performed at the amino terminus and carboxyl terminus. Except for S78A and D233A/T202A, which exhibited V(1)V(o) assembly defects, the function of subunit E was resistant to mutations. Most mutations complemented the growth phenotype of vma4Delta mutants, including T6A and D233A, which only had 25% of the wild-type ATPase activity. Residues Ser-78 and Thr-202 were essential for V(1)V(o) assembly and function. The mutation S78A destabilized subunit E and prevented assembly of V(1) subunits at the membranes. Mutant T202A membranes exhibited 2-fold increased V(max) and about 2-fold less of V(1)V(o) assembly; the mutation increased the specific activity of V(1)V(o) by enhancing the k(cat) of the enzyme 4-fold. Reduced levels of V(1)V(o) and V(o) complexes at T202A membranes suggest that the balance between V(1)V(o) and V(o) was not perturbed; instead, cells adjusted the amount of assembled V-ATPase complexes in order to compensate for the enhanced activity. These results indicated communication between subunit E and the catalytic sites at the A(3)B(3) hexamer and suggest potential regulatory roles for the carboxyl end of subunit E. At the carboxyl end, alanine substitution of Asp-233 significantly reduced ATP hydrolysis, although the truncation 229-233Delta and the point mutation K230A did not affect assembly and activity. The implication of these results for the topology and functions of subunit E within the V-ATPase complex are discussed.
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Affiliation(s)
- Margaret A Owegi
- Department of Chemistry, Ball State University, Muncie, Indiana 47306, USA
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Schredelseker J, Pelster B. Isoforms vatB1 and vatB2 of the vacuolar type ATPase subunit B are differentially expressed in embryos of the zebrafish (Danio rerio). Dev Dyn 2004; 230:569-75. [PMID: 15188441 DOI: 10.1002/dvdy.20074] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The v-type ATPase is a membrane anchored, multi-subunit proton pump, which in freshwater fish appears to play a major role in ionoregulative processes in the apical membrane of specialized gill cells. Very little is known about free-living fish embryos and larvae that are exposed to hypo-osmotic conditions with spawning but do not have their gills fully developed. By using reverse transcriptase-polymerase chain reaction and immunological methods, we could demonstrate the presence of two isoforms of the subunit B of this v-type ATPase in the early development of the zebrafish. Immunohistochemical analysis revealed the presence of one isoform (vatB1) in the apical membrane of embryonic skin cells, while vatB2 has been found ubiquitously. This differential localization of the two isoforms supports the hypothesis that vatB1 is preferentially involved in ionoregulative functions, while vatB2 may be preferentially responsible for acidification of intracellular vesicles.
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Sun-Wada GH, Wada Y, Futai M. Vacuolar H+ pumping ATPases in luminal acidic organelles and extracellular compartments: common rotational mechanism and diverse physiological roles. J Bioenerg Biomembr 2004; 35:347-58. [PMID: 14635780 DOI: 10.1023/a:1025780932403] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cytoplasmic organelles with an acidic luminal pH include vacuoles, coated vesicles, lysosomes, the Golgi apparatus, and synaptic vesicles. Acidic compartments are also known outside specialized cells such as osteoclasts. The unique acidic pH is formed by V-ATPase (Vacuolar type ATPase), other ion transporters, and the buffering action of proteins inside the organelles. V-ATPase hydrolyzes ATP and transports protons inside an organelle or extracellular compartment. We have summarized recent progress on mouse V-ATPases and their varying localizations together with their mechanism emphasizing similarities with F-type ATPases.
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Affiliation(s)
- Ge-Hong Sun-Wada
- Division of Biological Sciences and Nanoscience, and Nanotechnology Center, Japan Science and Technology Cooperation, Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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Futai M, Sun-Wada GH, Wada Y. Proton pumping ATPases and diverse inside-acidic compartments. YAKUGAKU ZASSHI 2004; 124:243-60. [PMID: 15118237 DOI: 10.1248/yakushi.124.243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proton-translocating ATPases are essential cellular energy converters that transduce the chemical energy of ATP hydrolysis into transmembrane proton electrochemical potential differences. The structures, catalytic mechanism, and cellular functions of three major classes of ATPases including the F-type, V-type, and P-type ATPase are discussed in this review. Physiological roles of the acidic organelles and compartments contained are also discussed.
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Affiliation(s)
- Masamitsu Futai
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki City, Osaka 567-0047, Japan.
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Nishi T, Kawasaki-Nishi S, Forgac M. Expression and function of the mouse V-ATPase d subunit isoforms. J Biol Chem 2003; 278:46396-402. [PMID: 12963731 DOI: 10.1074/jbc.m303924200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified a cDNA encoding a novel isoform of the mouse V-ATPase d subunit (d2). The protein encoded is 350 amino acids in length and shows 42 and 67% identity to the yeast d subunit (Vma6p) and the mouse d1 isoform, respectively. Reverse transcriptase-PCR analysis using isoform-specific primers demonstrate that d2 is expressed mainly in kidney and at lower levels in heart, spleen, skeletal muscle, and testis. Although d1 and d2 show similar levels of sequence homology to Vma6p, only the d1 isoform can complement the phenotype of a yeast strain in which VMA6 has been disrupted when cells are grown at 30 degrees C. The d2 isoform, however, can complement the vma6Delta phenotype when cells are grown at 25 degrees C. Moreover, partial assembly of the V-ATPase complex on the vacuolar membrane can be detected under these conditions, although assembly is significantly lower than that observed for the strain expressing Vma6p. This reduced assembly is also reflected in a reduced level of concanamycin-sensitive ATPase activity and proton transport in isolated vacuoles. Comparison of the kinetic properties of V-ATPase complexes containing Vma6p and d1 demonstrate that although the Km for ATP hydrolysis is similar (0.26 and 0.31 mm, respectively), the coupling ratio (proton transport/ATP hydrolysis) is approximately 3-6-fold higher for d1-containing complexes than for Vma6p-containing complexes. These results suggest that subunit d may play a role in coupling of proton transport and ATP hydrolysis.
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Affiliation(s)
- Tsuyoshi Nishi
- Department of Physiology, Tufts University School of Medicine, Boston, MA 02111, USA
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Sun-Wada GH, Murata Y, Namba M, Yamamoto A, Wada Y, Futai M. Mouse proton pump ATPase C subunit isoforms (C2-a and C2-b) specifically expressed in kidney and lung. J Biol Chem 2003; 278:44843-51. [PMID: 12947086 DOI: 10.1074/jbc.m307197200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vacuolar-type H+-ATPases (V-ATPases) are multimeric proton pumps involved in a wide variety of physiological processes. We have identified two alternative splicing variants of C2 subunit isoforms: C2-a, a lung-specific isoform containing a 46-amino acid insertion, and C2-b, a kidney-specific isoform without the insert. Immunohistochemistry with isoform-specific antibodies revealed that V-ATPase with C2-a is localized specifically in lamellar bodies of type II alveolar cells, whereas the C2-b isoform is found in the plasma membranes of renal alpha and beta intercalated cells. Immunoprecipitation combined with immunohistological analysis revealed that C2-b together with other kidney-specific isoforms was selectively assembled to form a unique proton pump in intercalated cells. Furthermore, a chimeric yeast V-ATPase with mouse the C2-a or C2-b isoform showed a lower Km(ATP) and lower proton transport activity than that with C1 or Vma5p (yeast C subunit). These results suggest that V-ATPases with the C2-a and C2-b isoform are involved in luminal acidification of lamellar bodies and regulation of the renal acid-base balance, respectively.
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Affiliation(s)
- Ge-Hong Sun-Wada
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
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Hirata T, Iwamoto-Kihara A, Sun-Wada GH, Okajima T, Wada Y, Futai M. Subunit rotation of vacuolar-type proton pumping ATPase: relative rotation of the G and C subunits. J Biol Chem 2003; 278:23714-9. [PMID: 12670943 DOI: 10.1074/jbc.m302756200] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vacuolar-type ATPases V1V0 (V-ATPases) are found ubiquitously in the endomembrane organelles of eukaryotic cells. In this study, we genetically introduced a His tag and a biotin tag onto the c and G subunits, respectively, of Saccharomyces cerevisiae V-ATPase. Using this engineered enzyme, we observed directly the continuous counter-clockwise rotation of an actin filament attached to the G subunit when the enzyme was immobilized on a glass surface through the c subunit. V-ATPase generated essentially the same torque as the F-ATPase (ATP synthase). The rotation was inhibited by concanamycin and nitrate but not by azide. These results demonstrated that the V- and F-ATPase carry out a common rotational catalysis.
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Affiliation(s)
- Tomoyuki Hirata
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
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Toyomura T, Murata Y, Yamamoto A, Oka T, Sun-Wada GH, Wada Y, Futai M. From lysosomes to the plasma membrane: localization of vacuolar-type H+ -ATPase with the a3 isoform during osteoclast differentiation. J Biol Chem 2003; 278:22023-30. [PMID: 12672822 DOI: 10.1074/jbc.m302436200] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Osteoclasts generate a massive acid flux to mobilize bone calcium. Local extracellular acidification is carried out by vacuolar type H+-ATPase (V-ATPase) localized in the plasma membrane. We have shown that a3, one of the four subunit a isoforms (a1, a2, a3, and a4), is a component of the plasma membrane V-ATPase (Toyomura, T., Oka, T., Yamaguchi, C., Wada, Y., and Futai, M. (2000) J. Biol. Chem. 275, 8760-8765). To establish the unique localization of V-ATPase, we have used a murine macrophage cell line, RAW 264.7, that can differentiate into multinuclear osteoclast-like cells on stimulation with RANKL (receptor activator of nuclear factor kappaB ligand). The V-ATPase with the a3 isoform was localized to late endosomes and lysosomes, whereas those with the a1 and a2 isoforms were localized to organelles other than lysosomes. After stimulation, the V-ATPase with the a3 isoform was immunochemically colocalized with lysosome marker lamp2 and was detected in acidic organelles. These organelles were also colocalized with microtubules, and the signals of lamp2 and a3 were dispersed by nocodazole, a microtubule depolymerizer. In RAW-derived osteoclasts cultured on mouse skull pieces, the a3 isoform was transported to the plasma membrane facing the bone and accumulated inside podosome rings. These findings indicate that V-ATPases with the a3 isoform localized in late endosomes/lysosomes are transported to the cell periphery during differentiation and finally assembled into the plasma membrane of mature osteoclasts.
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Affiliation(s)
- Takao Toyomura
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
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Boesch ST, Eller B, Pelster B. Expression of two isoforms of the vacuolar-type ATPase subunit B in the zebrafish Danio rerio. J Exp Biol 2003; 206:1907-15. [PMID: 12728012 DOI: 10.1242/jeb.00378] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the present study we tested the hypothesis that two isoforms of the regulatory subunit B of vacuolar-type ATPase (V-ATPase) are expressed in the zebrafish Danio rerio. The complete coding sequences for both isoforms, vatB1 and vatB2, were cloned and sequenced. BLASTX analysis revealed the greatest similarity to amino acid sequences of B subunits from the European eel Anguilla anguilla and rainbow trout Oncorhynchus mykiss. The isoforms were expressed in a bacterial system and the recombinant proteins verified using isoform-specific antibodies directed against vatB isoforms of the eel. The distribution of both isoforms in zebrafish tissues was investigated using reverse transcriptase-polymerase chain reaction and western blot analysis. The results revealed that at the RNA level both isoforms were expressed in all tested organs, i.e. the gills, swimbladder, heart, kidney, liver, spleen, intestine and skeletal muscle. At the protein level, however, there were tissue-specific variations in the levels of the two vatB isoforms expressed. The highest amounts of V-ATPase were detected in total protein preparations from gill, heart and liver tissue. In liver tissue, however, the western blot analysis indicated that vatB1 was not as prominent as vatB2, and immunohistochemistry revealed that antibodies directed against vatB1 yielded a very weak staining in a number of cells, while an antibody directed against vatB1 and vatB2 yielded a strong staining in virtually every cell. Similarly, neurosecretory cells of the small intestine were stained with an antibody directed against vatB1 and vatB2, but not with an antibody specific for vatB1. Therefore we conclude that the differential expression of two isoforms of the V-ATPase subunits, which may serve different functions as in several mammalian species, may also be a common phenomenon in teleost fish.
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Affiliation(s)
- S T Boesch
- Institut für Zoologie und Limnologie, Universität Innsbruck, Austria
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Sun-Wada GH, Yoshimizu T, Imai-Senga Y, Wada Y, Futai M. Diversity of mouse proton-translocating ATPase: presence of multiple isoforms of the C, d and G subunits. Gene 2003; 302:147-53. [PMID: 12527205 DOI: 10.1016/s0378-1119(02)01099-5] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vacuolar-type proton-translocating ATPases (V-ATPases), multimeric proton pumps, are involved in a wide variety of physiological processes. For their diverse functions, V-ATPases utilize a specific subunit isoform(s). Here, we reported the molecular cloning and characterization of three novel subunit isoforms, C2, d2 and G3, of mouse V-ATPase. These isoforms were expressed in a tissue-specific manner, in contrast to the ubiquitously expressed C1, d1 and G1 isoforms. C2 was expressed predominantly in lung and kidney, and d2 and G3 specifically in kidney. We introduced these isoforms into yeasts lacking the corresponding genes. Although the G3 and d2 did not rescue the vmaDelta phenotype, d1 and the two C isoforms functionally complemented the Deltavma6 and Deltavma5, respectively, indicating that they are bona fide subunits of V-ATPase.
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Affiliation(s)
- Ge-Hong Sun-Wada
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, and CREST (Core Research for Evolutional Science and Technology), Japan Science and Technology Corp., Mihogaoka 8-1, Ibaraki-shi, Osaka 567-0047, Japan
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