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Fang Y, Feng H, Zhang B, Zhang S, Zhou Y, Hao P, Zhou Z, Zhou S, Li N, Hui Y, Ma L, Xiong J, Wu J, Liu L, Zhang X. Cytosolic pH is a direct nexus in linking environmental cues with insulin processing and secretion in pancreatic β cells. Cell Metab 2024; 36:1237-1251.e4. [PMID: 38513648 DOI: 10.1016/j.cmet.2024.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 09/01/2023] [Accepted: 02/22/2024] [Indexed: 03/23/2024]
Abstract
Pancreatic β cells actively respond to glucose fluctuations through regulating insulin processing and secretion. However, how this process is elaborately tuned in circumstance of variable microenvironments as well as β cell-intrinsic states and whether its dysfunction links to metabolic diseases remain largely elusive. Here, we show that the cytosolic pH (pHc) in β cells is increased upon glucose challenge, which can be sensed by Smad5 via its nucleocytoplasmic shuttling. Lesion of Smad5 in β cells results in hyperglycemia and glucose intolerance due to insulin processing and secretion deficiency. The role of Smad5 in regulating insulin processing and secretion attributes to its non-canonical function by regulating V-ATPase activity for granule acidification. Genetic mutation of Smad5 or administration of alkaline water to mirror cytosolic alkalization ameliorated glucose intolerance in high-fat diet (HFD)-treated mice. Collectively, our findings suggest that pHc is a direct nexus in linking environmental cues with insulin processing and secretion in β cells.
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Affiliation(s)
- Yujiang Fang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.
| | - Hexi Feng
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Bowen Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Shuwei Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Yanjie Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Pengcheng Hao
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Zhongshu Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Shanshan Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Nan Li
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Yi Hui
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Lin Ma
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Jie Xiong
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Jinjin Wu
- Shanghai Children's Medical Center, Shanghai Jiaotong University, Shanghai, China
| | - Ling Liu
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.
| | - Xiaoqing Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China; Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China; Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China; Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China; Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China; Clinical Center for Brain and Spinal Cord Research, Tongji University, Shanghai, China.
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Prasad H, Mandal S, Mathew JKK, Cherukunnath A, Duddu AS, Banerjee M, Ramani H, Bhat R, Jolly MK, Visweswariah SS. An Endosomal Acid-Regulatory Feedback System Rewires Cytosolic cAMP Metabolism and Drives Tumor Progression. Mol Cancer Res 2024; 22:465-481. [PMID: 38319300 DOI: 10.1158/1541-7786.mcr-23-0606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 01/02/2024] [Accepted: 02/02/2024] [Indexed: 02/07/2024]
Abstract
Although suppressed cAMP levels have been linked to cancer for nearly five decades, the molecular basis remains uncertain. Here, we identify endosomal pH as a novel regulator of cytosolic cAMP homeostasis and a promoter of transformed phenotypic traits in colorectal cancer. Combining experiments and computational analysis, we show that the Na+/H+ exchanger NHE9 contributes to proton leak and causes luminal alkalinization, which induces resting [Ca2+], and in consequence, represses cAMP levels, creating a feedback loop that echoes nutrient deprivation or hypoxia. Higher NHE9 expression in cancer epithelia is associated with a hybrid epithelial-mesenchymal (E/M) state, poor prognosis, tumor budding, and invasive growth in vitro and in vivo. These findings point to NHE9-mediated cAMP suppression as a pseudostarvation-induced invasion state and potential therapeutic vulnerability in colorectal cancer. Our observations lay the groundwork for future research into the complexities of endosome-driven metabolic reprogramming and phenotype switching and the biology of cancer progression. IMPLICATIONS Endosomal pH regulator NHE9 actively controls cytosolic Ca2+ levels to downregulate the adenylate cyclase-cAMP system, enabling colorectal cancer cells to acquire hybrid E/M characteristics and promoting metastatic progression.
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Affiliation(s)
- Hari Prasad
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Susmita Mandal
- Department of Bioengineering, Indian Institute of Science, Bengaluru, Karnataka, India
| | | | - Aparna Cherukunnath
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | | | - Mallar Banerjee
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Harini Ramani
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Ramray Bhat
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
- Department of Bioengineering, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Mohit Kumar Jolly
- Department of Bioengineering, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Sandhya S Visweswariah
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
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Klössel S, Zhu Y, Amado L, Bisinski DD, Ruta J, Liu F, González Montoro A. Yeast TLDc domain proteins regulate assembly state and subcellular localization of the V-ATPase. EMBO J 2024; 43:1870-1897. [PMID: 38589611 PMCID: PMC11066047 DOI: 10.1038/s44318-024-00097-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 04/10/2024] Open
Abstract
Yeast vacuoles perform crucial cellular functions as acidic degradative organelles, storage compartments, and signaling hubs. These functions are mediated by important protein complexes, including the vacuolar-type H+-ATPase (V-ATPase), responsible for organelle acidification. To gain a more detailed understanding of vacuole function, we performed cross-linking mass spectrometry on isolated vacuoles, detecting many known as well as novel protein-protein interactions. Among these, we identified the uncharacterized TLDc-domain-containing protein Rtc5 as a novel interactor of the V-ATPase. We further analyzed the influence of Rtc5 and of Oxr1, the only other yeast TLDc-domain-containing protein, on V-ATPase function. We find that both Rtc5 and Oxr1 promote the disassembly of the vacuolar V-ATPase in vivo, counteracting the role of the RAVE complex, a V-ATPase assembly chaperone. Furthermore, Oxr1 is necessary for the retention of a Golgi-specific subunit of the V-ATPase in this compartment. Collectively, our results shed light on the in vivo roles of yeast TLDc-domain proteins as regulators of the V-ATPase, highlighting the multifaceted regulation of this crucial protein complex.
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Affiliation(s)
- Samira Klössel
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany
| | - Ying Zhu
- Department of Structural Biology, Leibniz - Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, Berlin, 13125, Germany
| | - Lucia Amado
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany
| | - Daniel D Bisinski
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany
| | - Julia Ruta
- Department of Structural Biology, Leibniz - Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, Berlin, 13125, Germany
| | - Fan Liu
- Department of Structural Biology, Leibniz - Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, Berlin, 13125, Germany
- Charité - Universitätsmedizin Berlin, Charitépl. 1, 10117, Berlin, Germany
| | - Ayelén González Montoro
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany.
- Osnabrück University, Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Barbarastrasse 11, 49076, Osnabrück, Germany.
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Direct control of lysosomal catabolic activity by mTORC1 through regulation of V-ATPase assembly. Nat Commun 2022; 13:4848. [PMID: 35977928 PMCID: PMC9385660 DOI: 10.1038/s41467-022-32515-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 08/03/2022] [Indexed: 12/15/2022] Open
Abstract
Mammalian cells can acquire exogenous amino acids through endocytosis and lysosomal catabolism of extracellular proteins. In amino acid-replete environments, nutritional utilization of extracellular proteins is suppressed by the amino acid sensor mechanistic target of rapamycin complex 1 (mTORC1) through an unknown process. Here, we show that mTORC1 blocks lysosomal degradation of extracellular proteins by suppressing V-ATPase-mediated acidification of lysosomes. When mTORC1 is active, peripheral V-ATPase V1 domains reside in the cytosol where they are stabilized by association with the chaperonin TRiC. Consequently, most lysosomes display low catabolic activity. When mTORC1 activity declines, V-ATPase V1 domains move to membrane-integral V-ATPase Vo domains at lysosomes to assemble active proton pumps. The resulting drop in luminal pH increases protease activity and degradation of protein contents throughout the lysosomal population. These results uncover a principle by which cells rapidly respond to changes in their nutrient environment by mobilizing the latent catabolic capacity of lysosomes. mTORC1 blocks lysosomal nutrient generation. Here, the authors show that mTORC1 inactivation triggers V-ATPase assembly, which rapidly initiates lysosomal acidification and degradation of protein contents throughout the lysosomal population.
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Seidel T. The Plant V-ATPase. FRONTIERS IN PLANT SCIENCE 2022; 13:931777. [PMID: 35845650 PMCID: PMC9280200 DOI: 10.3389/fpls.2022.931777] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/03/2022] [Indexed: 05/25/2023]
Abstract
V-ATPase is the dominant proton pump in plant cells. It contributes to cytosolic pH homeostasis and energizes transport processes across endomembranes of the secretory pathway. Its localization in the trans Golgi network/early endosomes is essential for vesicle transport, for instance for the delivery of cell wall components. Furthermore, it is crucial for response to abiotic and biotic stresses. The V-ATPase's rather complex structure and multiple subunit isoforms enable high structural flexibility with respect to requirements for different organs, developmental stages, and organelles. This complexity further demands a sophisticated assembly machinery and transport routes in cells, a process that is still not fully understood. Regulation of V-ATPase is a target of phosphorylation and redox-modifications but also involves interactions with regulatory proteins like 14-3-3 proteins and the lipid environment. Regulation by reversible assembly, as reported for yeast and the mammalian enzyme, has not be proven in plants but seems to be absent in autotrophic cells. Addressing the regulation of V-ATPase is a promising approach to adjust its activity for improved stress resistance or higher crop yield.
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Endosomal v-ATPase as a Sensor Determining Myocardial Substrate Preference. Metabolites 2022; 12:metabo12070579. [PMID: 35888703 PMCID: PMC9316095 DOI: 10.3390/metabo12070579] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/16/2022] [Accepted: 06/20/2022] [Indexed: 11/17/2022] Open
Abstract
The heart is a metabolically flexible omnivore that can utilize a variety of substrates for energy provision. To fulfill cardiac energy requirements, the healthy adult heart mainly uses long-chain fatty acids and glucose in a balanced manner, but when exposed to physiological or pathological stimuli, it can switch its substrate preference to alternative substrates such as amino acids (AAs) and ketone bodies. Using the failing heart as an example, upon stress, the fatty acid/glucose substrate balance is upset, resulting in an over-reliance on either fatty acids or glucose. A chronic fuel shift towards a single type of substrate is linked with cardiac dysfunction. Re-balancing myocardial substrate preference is suggested as an effective strategy to rescue the failing heart. In the last decade, we revealed that vacuolar-type H+-ATPase (v-ATPase) functions as a key regulator of myocardial substrate preference and, therefore, as a novel potential treatment approach for the failing heart. Fatty acids, glucose, and AAs selectively influence the assembly state of v-ATPase resulting in modulation of its proton-pumping activity. In this review, we summarize these novel insights on v-ATPase as an integrator of nutritional information. We also describe its exploitation as a therapeutic target with focus on supplementation of AA as a nutraceutical approach to fight lipid-induced insulin resistance and contractile dysfunction of the heart.
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Zhou X, Li J, Tang N, Xie H, Fan X, Chen H, Tang M, Xie X. Genome-Wide Analysis of Nutrient Signaling Pathways Conserved in Arbuscular Mycorrhizal Fungi. Microorganisms 2021; 9:1557. [PMID: 34442636 PMCID: PMC8401276 DOI: 10.3390/microorganisms9081557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 01/03/2023] Open
Abstract
Arbuscular mycorrhizal (AM) fungi form a mutualistic symbiosis with a majority of terrestrial vascular plants. To achieve an efficient nutrient trade with their hosts, AM fungi sense external and internal nutrients, and integrate different hierarchic regulations to optimize nutrient acquisition and homeostasis during mycorrhization. However, the underlying molecular networks in AM fungi orchestrating the nutrient sensing and signaling remain elusive. Based on homology search, we here found that at least 72 gene components involved in four nutrient sensing and signaling pathways, including cAMP-dependent protein kinase A (cAMP-PKA), sucrose non-fermenting 1 (SNF1) protein kinase, target of rapamycin kinase (TOR) and phosphate (PHO) signaling cascades, are well conserved in AM fungi. Based on the knowledge known in model yeast and filamentous fungi, we outlined the possible gene networks functioning in AM fungi. These pathways may regulate the expression of downstream genes involved in nutrient transport, lipid metabolism, trehalase activity, stress resistance and autophagy. The RNA-seq analysis and qRT-PCR results of some core genes further indicate that these pathways may play important roles in spore germination, appressorium formation, arbuscule longevity and sporulation of AM fungi. We hope to inspire further studies on the roles of these candidate genes involved in these nutrient sensing and signaling pathways in AM fungi and AM symbiosis.
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Affiliation(s)
- Xiaoqin Zhou
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Jiangyong Li
- Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China;
| | - Nianwu Tang
- UMR Interactions Arbres/Microorganismes, Centre INRA-Grand Est-Nancy, 54280 Champenoux, France;
| | - Hongyun Xie
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Xiaoning Fan
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Hui Chen
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Ming Tang
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Xianan Xie
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
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Lee H, Koh JY. Roles for H + /K + -ATPase and zinc transporter 3 in cAMP-mediated lysosomal acidification in bafilomycin A1-treated astrocytes. Glia 2020; 69:1110-1125. [PMID: 33314298 DOI: 10.1002/glia.23952] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 11/07/2022]
Abstract
Vacuolar ATPase (v-ATPase) is the main proton pump that acidifies vesicles such as lysosomes. Disruption in the lysosomal localization of v-ATPase leads to lysosomal dysfunction, thus contributing to the pathogenesis of lysosomal storage disorders and neurodegenerative diseases such as Alzheimer's disease. Recent studies showed that increases in cyclic AMP (cAMP) levels acidify lysosomes and consequently enhance autophagy flux. Although the upregulation of v-ATPase function may be the key mechanism underlying the cAMP-mediated lysosomal acidification, it is unknown whether a mechanism independent of v-ATPase may be contributing to this phenomenon. In the present study, we modeled v-ATPase dysfunction in brain cells by blocking lysosomal acidification in cortical astrocytes through treatment with bafilomycin A1, a selective v-ATPase inhibitor. We observed that cAMP reversed the pH changes via the activation of protein kinase A; interestingly, cAMP also increased autophagy flux even in the presence of bafilomycin A1, suggesting the presence of an alternative route of proton entry. Notably, pharmacological inhibitors and siRNAs of H+ /K+ -ATPase markedly shifted the lysosomal pH toward more alkaline values in bafilomycin A1/cAMP-treated astrocytes, suggesting that H+ /K+ -ATPase may be the alternative route of proton entry for lysosomal acidification. Furthermore, the cAMP-mediated reversal of lysosomal pH was nullified in the absence of ZnT3 that interacts with H+ /K+ -ATPase. Our results suggest that the H+ /K+ -ATPase/ZnT3 complex is recruited to lysosomes in a cAMP-dependent manner and functions as an alternative proton pump for lysosomes when the v-ATPase function is downregulated, thus providing insight into the potential development of a new class of lysosome-targeted therapeutics in neurodegenerative diseases.
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Affiliation(s)
- Huikyong Lee
- Neural Injury Laboratory, Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Jae-Young Koh
- Neural Injury Laboratory, Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.,Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
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Dhakal S, Macreadie I. Protein Homeostasis Networks and the Use of Yeast to Guide Interventions in Alzheimer's Disease. Int J Mol Sci 2020; 21:E8014. [PMID: 33126501 PMCID: PMC7662794 DOI: 10.3390/ijms21218014] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/24/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's Disease (AD) is a progressive multifactorial age-related neurodegenerative disorder that causes the majority of deaths due to dementia in the elderly. Although various risk factors have been found to be associated with AD progression, the cause of the disease is still unresolved. The loss of proteostasis is one of the major causes of AD: it is evident by aggregation of misfolded proteins, lipid homeostasis disruption, accumulation of autophagic vesicles, and oxidative damage during the disease progression. Different models have been developed to study AD, one of which is a yeast model. Yeasts are simple unicellular eukaryotic cells that have provided great insights into human cell biology. Various yeast models, including unmodified and genetically modified yeasts, have been established for studying AD and have provided significant amount of information on AD pathology and potential interventions. The conservation of various human biological processes, including signal transduction, energy metabolism, protein homeostasis, stress responses, oxidative phosphorylation, vesicle trafficking, apoptosis, endocytosis, and ageing, renders yeast a fascinating, powerful model for AD. In addition, the easy manipulation of the yeast genome and availability of methods to evaluate yeast cells rapidly in high throughput technological platforms strengthen the rationale of using yeast as a model. This review focuses on the description of the proteostasis network in yeast and its comparison with the human proteostasis network. It further elaborates on the AD-associated proteostasis failure and applications of the yeast proteostasis network to understand AD pathology and its potential to guide interventions against AD.
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Affiliation(s)
| | - Ian Macreadie
- School of Science, RMIT University, Bundoora, Victoria 3083, Australia;
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10
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Collins MP, Stransky LA, Forgac M. AKT Ser/Thr kinase increases V-ATPase-dependent lysosomal acidification in response to amino acid starvation in mammalian cells. J Biol Chem 2020; 295:9433-9444. [PMID: 32409581 PMCID: PMC7363138 DOI: 10.1074/jbc.ra120.013223] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/13/2020] [Indexed: 12/12/2022] Open
Abstract
The vacuolar H+-ATPase (V-ATPase) is an ATP-dependent proton pump that is essential for cellular homeostasis. V-ATPase activity is controlled by the regulated assembly of the enzyme from its component V1 and V0 domains. We previously reported that amino acid starvation rapidly increases V-ATPase assembly and activity in mammalian lysosomes, but the signaling pathways controlling this effect are unknown. In testing inhibitors of pathways important for controlling cellular metabolism, we found here that the cAMP-dependent protein kinase (PKA) inhibitor H89 increases lysosomal V-ATPase activity and blocks any further change upon starvation. The AMP-activated protein kinase (AMPK) inhibitor dorsomorphin decreased lysosomal V-ATPase activity and also blocked any increase upon starvation. However, CRISPR-mediated gene editing revealed that PKA and AMPK are not required for the starvation-dependent increase in lysosomal V-ATPase activity, indicating that H89 and dorsomorphin modify V-ATPase activity through other cellular targets. We next found that the AKT Ser/Thr kinase (AKT) inhibitor MK2206 blocks the starvation-dependent increase in lysosomal V-ATPase activity without altering basal activity. Expression of AKT1 or AKT3, but not AKT2, was required for increased lysosomal V-ATPase activity in response to amino acid starvation in mouse fibroblasts. Finally, HEK293T cells expressing only AKT1 responded normally to starvation, whereas cells expressing only AKT2 displayed a significantly reduced increase in V-ATPase activity and assembly upon starvation. These results show that AKT is required for controlling the rapid response of lysosomal V-ATPase activity to changes in amino acid availability and that this response depends on specific AKT isoforms.
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Affiliation(s)
- Michael P Collins
- Program in Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
| | - Laura A Stransky
- Program in Cellular and Molecular Physiology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
| | - Michael Forgac
- Program in Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
- Program in Cellular and Molecular Physiology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
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Collins MP, Forgac M. Regulation and function of V-ATPases in physiology and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183341. [PMID: 32422136 DOI: 10.1016/j.bbamem.2020.183341] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 02/07/2023]
Abstract
The vacuolar H+-ATPases (V-ATPases) are essential, ATP-dependent proton pumps present in a variety of eukaryotic cellular membranes. Intracellularly, V-ATPase-dependent acidification functions in such processes as membrane traffic, protein degradation, autophagy and the coupled transport of small molecules. V-ATPases at the plasma membrane of certain specialized cells function in such processes as bone resorption, sperm maturation and urinary acidification. V-ATPases also function in disease processes such as pathogen entry and cancer cell invasiveness, while defects in V-ATPase genes are associated with disorders such as osteopetrosis, renal tubular acidosis and neurodegenerative diseases. This review highlights recent advances in our understanding of V-ATPase structure, mechanism, function and regulation, with an emphasis on the signaling pathways controlling V-ATPase assembly in mammalian cells. The role of V-ATPases in cancer and other human pathologies, and the prospects for therapeutic intervention, are also discussed.
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Affiliation(s)
- Michael P Collins
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America
| | - Michael Forgac
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America; Dept. of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, United States of America.
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12
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Nixon RA. The aging lysosome: An essential catalyst for late-onset neurodegenerative diseases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140443. [PMID: 32416272 DOI: 10.1016/j.bbapap.2020.140443] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 05/04/2020] [Accepted: 05/07/2020] [Indexed: 01/13/2023]
Abstract
Lysosomes figure prominently in theories of aging as the proteolytic system most responsible for eliminating growing burdens of damaged proteins and organelles in aging neurons and other long lived cells. Newer evidence shows that diverse experimental measures known to extend lifespan in invertebrate aging models share the property of boosting lysosomal clearance of substrates through the autophagy pathway. Maintaining an optimal level of lysosome acidification is particularly crucial for these anti-aging effects. The exceptional dependence of neurons on fully functional lysosomes is reflected by the neurological phenotypes that develop in congenital lysosomal storage disorders, which commonly present as severe neurodevelopmental or neurodegenerative conditions even though the lysosomal deficit maybe systemic. Similar connections are now being appreciated between primary lysosomal deficit and the risk for late age-onset neurodegenerative disorders. In diseases such as Alzheimer's and Parkinson's, as in aging alone, primary lysosome dysfunction due to acidification impairment is emerging as a frequent theme, supported by the growing list of familial neurodegenerative disorders that involve primary vATPase dysfunction. The additional cellular roles played by intraluminal pH in sensing nutrient and stress and modulating cellular signaling have further expanded the possible ways that lysosomal pH dysregulation in aging and disease can disrupt neuronal function. Here, we consider the impact of cellular aging on lysosomes and how the changes during aging may create the tipping point for disease emergence in major late-age onset neurodegenerative disorders.
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Affiliation(s)
- Ralph A Nixon
- Center for Dementia Research, Nathan S. Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA; Department of Psychiatry, New York University Langone Medical Center, 550 First Ave, New York, NY 10016, USA; Department of Cell Biology, New York University Langone Medical Center, 550 First Ave, New York, NY 10016, USA; Department of NYU Neuroscience Institute, New York University Langone Medical Center, 550 First Ave, New York, NY 10016, USA.
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13
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Jaskolka MC, Kane PM. Interaction between the yeast RAVE complex and Vph1-containing V o sectors is a central glucose-sensitive interaction required for V-ATPase reassembly. J Biol Chem 2020; 295:2259-2269. [PMID: 31941791 DOI: 10.1074/jbc.ra119.011522] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
The yeast vacuolar H+-ATPase (V-ATPase) of budding yeast (Saccharomyces cerevisiae) is regulated by reversible disassembly. Disassembly inhibits V-ATPase activity under low-glucose conditions by releasing peripheral V1 subcomplexes from membrane-bound Vo subcomplexes. V-ATPase reassembly and reactivation requires intervention of the conserved regulator of H+-ATPase of vacuoles and endosomes (RAVE) complex, which binds to cytosolic V1 subcomplexes and assists reassembly with integral membrane Vo complexes. Consistent with its role, the RAVE complex itself is reversibly recruited to the vacuolar membrane by glucose, but the requirements for its recruitment are not understood. We demonstrate here that RAVE recruitment to the membrane does not require an interaction with V1 Glucose-dependent RAVE localization to the vacuolar membrane required only intact Vo complexes containing the Vph1 subunit, suggesting that the RAVE-Vo interaction is glucose-dependent. We identified a short conserved sequence in the center of the RAVE subunit Rav1 that is essential for the interaction with Vph1 in vivo and in vitro Mutations in this region resulted in the temperature- and pH-dependent growth phenotype characteristic of ravΔ mutants. However, this region did not account for glucose sensitivity of the Rav1-Vph1 interaction. We quantitated glucose-dependent localization of a GFP-tagged RAVE subunit to the vacuolar membrane in several mutants previously implicated in altering V-ATPase assembly state or glucose-induced assembly. RAVE localization did not correlate with V-ATPase assembly levels reported previously in these mutants, highlighting both the catalytic nature of RAVE's role in V-ATPase assembly and the likelihood of glucose signaling to RAVE independently of V1.
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Affiliation(s)
- Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210.
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14
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Glatz JFC, Luiken JJFP, Nabben M. CD36 (SR-B2) as a Target to Treat Lipid Overload-Induced Cardiac Dysfunction. J Lipid Atheroscler 2020; 9:66-78. [PMID: 32821722 PMCID: PMC7379071 DOI: 10.12997/jla.2020.9.1.66] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 01/05/2023] Open
Abstract
The heart faces the challenge of adjusting the rate of fatty acid uptake to match myocardial demand for energy provision at any given moment, avoiding both too low uptake rates, which could elicit an energy deficit, and too high uptake rates, which pose the risk of excess lipid accumulation and lipotoxicity. The transmembrane glycoprotein cluster of differentiation 36 (CD36), a scavenger receptor (B2), serves many functions in lipid metabolism and signaling. In the heart, CD36 is the main sarcolemmal lipid transporter involved in the rate-limiting kinetic step in cardiac lipid utilization. The cellular fatty acid uptake rate is determined by the presence of CD36 at the cell surface, which is regulated by subcellular vesicular recycling from endosomes to the sarcolemma. CD36 has been implicated in dysregulated fatty acid and lipid metabolism in pathophysiological conditions, particularly high-fat diet-induced insulin resistance and diabetic cardiomyopathy. Thus, in conditions of chronic lipid overload, high levels of CD36 are moved to the sarcolemma, setting the heart on a route towards increased lipid uptake, excessive lipid accumulation, insulin resistance, and eventually contractile dysfunction. Insight into the subcellular trafficking machinery of CD36 will provide novel targets to treat the lipid-overloaded heart. A screen for CD36-dedicated trafficking proteins found that vacuolar-type H+-ATPase and specific vesicle-associated membrane proteins, among others, were uniquely involved in CD36 recycling. Preliminary data suggest that these proteins may offer clues on how to manipulate myocardial lipid uptake, and thus could be promising targets for metabolic intervention therapy to treat the failing heart.
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Affiliation(s)
- Jan F C Glatz
- Department of Genetics & Cell Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands
| | - Joost J F P Luiken
- Department of Genetics & Cell Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands
| | - Miranda Nabben
- Department of Genetics & Cell Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands
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15
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Cell organelles and yeast longevity: an intertwined regulation. Curr Genet 2019; 66:15-41. [PMID: 31535186 DOI: 10.1007/s00294-019-01035-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/12/2019] [Accepted: 09/12/2019] [Indexed: 12/16/2022]
Abstract
Organelles are dynamic structures of a eukaryotic cell that compartmentalize various essential functions and regulate optimum functioning. On the other hand, ageing is an inevitable phenomenon that leads to irreversible cellular damage and affects optimum functioning of cells. Recent research shows compelling evidence that connects organelle dysfunction to ageing-related diseases/disorders. Studies in several model systems including yeast have led to seminal contributions to the field of ageing in uncovering novel pathways, proteins and their functions, identification of pro- and anti-ageing factors and so on. In this review, we present a comprehensive overview of findings that highlight the role of organelles in ageing and ageing-associated functions/pathways in yeast.
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16
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Li M, Zhang CS, Zong Y, Feng JW, Ma T, Hu M, Lin Z, Li X, Xie C, Wu Y, Jiang D, Li Y, Zhang C, Tian X, Wang W, Yang Y, Chen J, Cui J, Wu YQ, Chen X, Liu QF, Wu J, Lin SY, Ye Z, Liu Y, Piao HL, Yu L, Zhou Z, Xie XS, Hardie DG, Lin SC. Transient Receptor Potential V Channels Are Essential for Glucose Sensing by Aldolase and AMPK. Cell Metab 2019; 30:508-524.e12. [PMID: 31204282 PMCID: PMC6720459 DOI: 10.1016/j.cmet.2019.05.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/03/2019] [Accepted: 05/21/2019] [Indexed: 02/06/2023]
Abstract
Fructose-1,6-bisphosphate (FBP) aldolase links sensing of declining glucose availability to AMPK activation via the lysosomal pathway. However, how aldolase transmits lack of occupancy by FBP to AMPK activation remains unclear. Here, we show that FBP-unoccupied aldolase interacts with and inhibits endoplasmic reticulum (ER)-localized transient receptor potential channel subfamily V, inhibiting calcium release in low glucose. The decrease of calcium at contact sites between ER and lysosome renders the inhibited TRPV accessible to bind the lysosomal v-ATPase that then recruits AXIN:LKB1 to activate AMPK independently of AMP. Genetic depletion of TRPVs blocks glucose starvation-induced AMPK activation in cells and liver of mice, and in nematodes, indicative of physical requirement of TRPVs. Pharmacological inhibition of TRPVs activates AMPK and elevates NAD+ levels in aged muscles, rejuvenating the animals' running capacity. Our study elucidates that TRPVs relay the FBP-free status of aldolase to the reconfiguration of v-ATPase, leading to AMPK activation in low glucose.
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Affiliation(s)
- Mengqi Li
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Chen-Song Zhang
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Yue Zong
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Jin-Wei Feng
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Teng Ma
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Meiqin Hu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, PKU-IDG/McGovern Institute for Brain Research, Peking University, 100871 Beijing, China
| | - Zhizhong Lin
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Xiaotong Li
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Changchuan Xie
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Yaying Wu
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Dong Jiang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Ying Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Cixiong Zhang
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Xiao Tian
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Wen Wang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Scientific Research Center for Translational Medicine, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
| | - Yanyan Yang
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, 100871 Beijing, China
| | - Jie Chen
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, 100871 Beijing, China
| | - Jiwen Cui
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Yu-Qing Wu
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Xin Chen
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Qing-Feng Liu
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Jianfeng Wu
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Shu-Yong Lin
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Zhiyun Ye
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China
| | - Ying Liu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, 100871 Beijing, China
| | - Hai-Long Piao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Scientific Research Center for Translational Medicine, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
| | - Li Yu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Zhuan Zhou
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, PKU-IDG/McGovern Institute for Brain Research, Peking University, 100871 Beijing, China
| | - Xiao-Song Xie
- McDermott Center of Human Growth and Development MC8591, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - D Grahame Hardie
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Sheng-Cai Lin
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102 Fujian, China.
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17
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Dolz‐Edo L, van der Deen M, Brul S, Smits GJ. Caloric restriction controls stationary phase survival through Protein Kinase A (PKA) and cytosolic pH. Aging Cell 2019; 18:e12921. [PMID: 30790427 PMCID: PMC6516148 DOI: 10.1111/acel.12921] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 12/30/2018] [Accepted: 01/23/2019] [Indexed: 11/28/2022] Open
Abstract
Calorie restriction is the only physiological intervention that extends lifespan throughout all kingdoms of life. In the budding yeast Saccharomyces cerevisiae, cytosolic pH (pHc) controls growth and responds to nutrient availability, decreasing upon glucose depletion. We investigated the interactions between glucose availability, pHc and the central nutrient signalling cAMP‐Protein Kinase A (PKA) pathway. Glucose abundance during the growth phase enhanced acidification upon glucose depletion, via modulation of PKA activity. This actively controlled reduction in starvation pHc correlated with reduced stationary phase survival. Whereas changes in PKA activity affected both acidification and survival, targeted manipulation of starvation pHc showed that cytosolic acidification was downstream of PKA and the causal agent of the reduced chronological lifespan. Thus, caloric restriction controls stationary phase survival through PKA and cytosolic pH.
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Affiliation(s)
- Laura Dolz‐Edo
- Department of Molecular Biology and Microbial Food Safety Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam The Netherlands
| | - Margaretha van der Deen
- Department of Molecular Biology and Microbial Food Safety Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam The Netherlands
| | - Stanley Brul
- Department of Molecular Biology and Microbial Food Safety Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam The Netherlands
| | - Gertien Jacoba Smits
- Department of Molecular Biology and Microbial Food Safety Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam The Netherlands
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18
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Deprez MA, Eskes E, Winderickx J, Wilms T. The TORC1-Sch9 pathway as a crucial mediator of chronological lifespan in the yeast Saccharomyces cerevisiae. FEMS Yeast Res 2019; 18:4980911. [PMID: 29788208 DOI: 10.1093/femsyr/foy048] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/19/2018] [Indexed: 12/18/2022] Open
Abstract
The concept of ageing is one that has intrigued mankind since the beginning of time and is now more important than ever as the incidence of age-related disorders is increasing in our ageing population. Over the past decades, extensive research has been performed using various model organisms. As such, it has become apparent that many fundamental aspects of biological ageing are highly conserved across large evolutionary distances. In this review, we illustrate that the unicellular eukaryotic organism Saccharomyces cerevisiae has proven to be a valuable tool to gain fundamental insights into the molecular mechanisms of cellular ageing in multicellular eukaryotes. In addition, we outline the current knowledge on how downregulation of nutrient signaling through the target of rapamycin (TOR)-Sch9 pathway or reducing calorie intake attenuates many detrimental effects associated with ageing and leads to the extension of yeast chronological lifespan. Given that both TOR Complex 1 (TORC1) and Sch9 have mammalian orthologues that have been implicated in various age-related disorders, unraveling the connections of TORC1 and Sch9 with yeast ageing may provide additional clues on how their mammalian orthologues contribute to the mechanisms underpinning human ageing and health.
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Affiliation(s)
- Marie-Anne Deprez
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Elja Eskes
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Tobias Wilms
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
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19
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Aufschnaiter A, Büttner S. The vacuolar shapes of ageing: From function to morphology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:957-970. [PMID: 30796938 DOI: 10.1016/j.bbamcr.2019.02.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 12/21/2022]
Abstract
Cellular ageing results in accumulating damage to various macromolecules and the progressive decline of organelle function. Yeast vacuoles as well as their counterpart in higher eukaryotes, the lysosomes, emerge as central organelles in lifespan determination. These acidic organelles integrate enzymatic breakdown and recycling of cellular waste with nutrient sensing, storage, signalling and mobilization. Establishing physical contact with virtually all other organelles, vacuoles serve as hubs of cellular homeostasis. Studies in Saccharomyces cerevisiae contributed substantially to our understanding of the ageing process per se and the multifaceted roles of vacuoles/lysosomes in the maintenance of cellular fitness with progressing age. Here, we discuss the multiple roles of the vacuole during ageing, ranging from vacuolar dynamics and acidification as determinants of lifespan to the function of this organelle as waste bin, recycling facility, nutrient reservoir and integrator of nutrient signalling.
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Affiliation(s)
- Andreas Aufschnaiter
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010 Graz, Austria
| | - Sabrina Büttner
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010 Graz, Austria; Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, 106 91 Stockholm, Sweden.
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20
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Hayek SR, Rane HS, Parra KJ. Reciprocal Regulation of V-ATPase and Glycolytic Pathway Elements in Health and Disease. Front Physiol 2019; 10:127. [PMID: 30828305 PMCID: PMC6384264 DOI: 10.3389/fphys.2019.00127] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/31/2019] [Indexed: 12/24/2022] Open
Abstract
The ability of cells to adapt to fluctuations in glucose availability is crucial for their survival and involves the vacuolar proton-translocating ATPase (V-ATPase), a proton pump found in all eukaryotes. V-ATPase hydrolyzes ATP via its V1 domain and uses the energy released to transport protons across membranes via its Vo domain. This activity is critical for pH homeostasis and generation of a membrane potential that drives cellular metabolism. A number of stimuli have been reported to alter V-ATPase assembly in yeast and higher eukaryotes. Glucose flux is one of the strongest and best-characterized regulators of V-ATPase; this review highlights current models explaining how glycolysis and V-ATPase are coordinated in both the Saccharomyces cerevisiae model fungus and in mammalian systems. Glucose-dependent assembly and trafficking of V-ATPase, V-ATPase-dependent modulations in glycolysis, and the recent discovery that glucose signaling through V-ATPase acts as a molecular switch to dictate anabolic versus catabolic metabolism are discussed. Notably, metabolic plasticity and altered glycolytic flux are critical drivers of numerous human pathologies, and the expression and activity of V-ATPase is often altered in disease states or can be pharmacologically manipulated as treatment. This overview will specifically discuss connections between V-ATPase and glycolysis in cancer.
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Affiliation(s)
- Summer R Hayek
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
| | - Hallie S Rane
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
| | - Karlett J Parra
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
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21
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Minematsu A, Miyazaki T, Shimamura S, Nishikawa H, Nakayama H, Takazono T, Saijo T, Yamamoto K, Imamura Y, Yanagihara K, Kohno S, Mukae H, Izumikawa K. Vacuolar proton-translocating ATPase is required for antifungal resistance and virulence of Candida glabrata. PLoS One 2019; 14:e0210883. [PMID: 30673768 PMCID: PMC6343876 DOI: 10.1371/journal.pone.0210883] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 01/03/2019] [Indexed: 12/04/2022] Open
Abstract
Vacuolar proton-translocating ATPase (V-ATPase) is located in fungal vacuolar membranes. It is involved in multiple cellular processes, including the maintenance of intracellular ion homeostasis by maintaining acidic pH within the cell. The importance of V-ATPase in virulence has been demonstrated in several pathogenic fungi, including Candida albicans. However, it remains to be determined in the clinically important fungal pathogen Candida glabrata. Increasing multidrug resistance of C. glabrata is becoming a critical issue in the clinical setting. In the current study, we demonstrated that the plecomacrolide V-ATPase inhibitor bafilomycin B1 exerts a synergistic effect with azole antifungal agents, including fluconazole and voriconazole, against a C. glabrata wild-type strain. Furthermore, the deletion of the VPH2 gene encoding an assembly factor of V-ATPase was sufficient to interfere with V-ATPase function in C. glabrata, resulting in impaired pH homeostasis in the vacuole and increased sensitivity to a variety of environmental stresses, such as alkaline conditions (pH 7.4), ion stress (Na+, Ca2+, Mn2+, and Zn2+ stress), exposure to the calcineurin inhibitor FK506 and antifungal agents (azoles and amphotericin B), and iron limitation. In addition, virulence of C. glabrata Δvph2 mutant in a mouse model of disseminated candidiasis was reduced in comparison with that of the wild-type and VPH2-reconstituted strains. These findings support the notion that V-ATPase is a potential attractive target for the development of effective antifungal strategies.
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Affiliation(s)
- Asuka Minematsu
- Department of Infectious Diseases, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Taiga Miyazaki
- Department of Infectious Diseases, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
- * E-mail:
| | - Shintaro Shimamura
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Hiroshi Nishikawa
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Hironobu Nakayama
- Faculty of Pharmaceutical Sciences, Suzuka University of Medical Sciences, Mie, Japan
| | - Takahiro Takazono
- Department of Infectious Diseases, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Tomomi Saijo
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Kazuko Yamamoto
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Yoshifumi Imamura
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Katsunori Yanagihara
- Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Shigeru Kohno
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Hiroshi Mukae
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Koichi Izumikawa
- Department of Infectious Diseases, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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22
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Sun G, Elowsky C, Li G, Wilson RA. TOR-autophagy branch signaling via Imp1 dictates plant-microbe biotrophic interface longevity. PLoS Genet 2018; 14:e1007814. [PMID: 30462633 PMCID: PMC6281275 DOI: 10.1371/journal.pgen.1007814] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 12/05/2018] [Accepted: 11/06/2018] [Indexed: 01/07/2023] Open
Abstract
Like other intracellular eukaryotic phytopathogens, the devastating rice blast fungus Magnaporthe (Pyricularia) oryzae first infects living host cells by elaborating invasive hyphae (IH) surrounded by a plant-derived membrane. This forms an extended biotrophic interface enclosing an apoplastic compartment into which fungal effectors can be deployed to evade host detection. M. oryzae also forms a focal, plant membrane-rich structure, the biotrophic interfacial complex (BIC), that accumulates cytoplasmic effectors for translocation into host cells. Molecular decision-making processes integrating fungal growth and metabolism in host cells with interface function and dynamics are unknown. Here, we report unanticipated roles for the M. oryzae Target-of-Rapamycin (TOR) nutrient-signaling pathway in mediating plant-fungal biotrophic interface membrane integrity. Through a forward genetics screen for M. oryzae mutant strains resistant to the specific TOR kinase inhibitor rapamycin, we discovered IMP1 encoding a novel vacuolar protein required for membrane trafficking, V-ATPase assembly, organelle acidification and autophagy induction. During infection, Δimp1 deletants developed intracellular IH in the first infected rice cell following cuticle penetration. However, fluorescently labeled effector probes revealed that interface membrane integrity became compromised as biotrophy progressed, abolishing the BIC and releasing apoplastic effectors into host cytoplasm. Growth between rice cells was restricted. TOR-independent autophagy activation in Δimp1 deletants (following infection) remediated interface function and cell-to-cell growth. Autophagy inhibition in wild type (following infection) recapitulated Δimp1. In addition to vacuoles, Imp1GFP localized to IH membranes in an autophagy-dependent manner. Collectively, our results suggest TOR-Imp1-autophagy branch signaling mediates membrane homeostasis to prevent catastrophic erosion of the biotrophic interface, thus facilitating fungal growth in living rice cells. The significance of this work lays in elaborating a novel molecular mechanism of infection stressing the dominance of fungal metabolism and metabolic control in sustaining long-term plant-microbe interactions. This work also has implications for understanding the enigmatic biotrophy to necrotrophy transition. Plant-associated fungi can form intimate connections with living host cells. Clarifying the molecular drivers of these interactions, and which partner is dominant, might be important in understanding how beneficial plant-fungal relationships can be enhanced to improve crop yields while pathogenic interactions that threaten crop health are disrupted. In common with other symbionts and phytopathogens, the devastating rice blast fungus Magnaporthe oryzae elaborates invasive hyphae in living host cells surrounded by plant-derived membranes. Nothing is known at the molecular signaling level about how such plant-microbe biotrophic interfacial zones are maintained as the fungus grows in and between host cells. Here, we report that fungal membrane trafficking processes controlled by nutrient signaling pathways are critical for maintaining biotrophic interface integrity during M. oryzae growth in rice cells. Impairing these processes resulted in erosion of the plant-microbe interface and failure of the fungus to thrive. To our knowledge, this work presents the first evidence indicating that the fungal partner is dominant in propagating the plant-microbe boundary. This suggests that the biotrophic interface is a fungal construct and provides clues on how such interfaces might be modulated to benefit the host plant.
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Affiliation(s)
- Guangchao Sun
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Christian Elowsky
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Gang Li
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Richard A. Wilson
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
- * E-mail:
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23
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Harrison MA, Muench SP. The Vacuolar ATPase - A Nano-scale Motor That Drives Cell Biology. Subcell Biochem 2018; 87:409-459. [PMID: 29464568 DOI: 10.1007/978-981-10-7757-9_14] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The vacuolar H+-ATPase (V-ATPase) is a ~1 MDa membrane protein complex that couples the hydrolysis of cytosolic ATP to the transmembrane movement of protons. In essentially all eukaryotic cells, this acid pumping function plays critical roles in the acidification of endosomal/lysosomal compartments and hence in transport, recycling and degradative pathways. It is also important in acid extrusion across the plasma membrane of some cells, contributing to homeostatic control of cytoplasmic pH and maintenance of appropriate extracellular acidity. The complex, assembled from up to 30 individual polypeptides, operates as a molecular motor with rotary mechanics. Historically, structural inferences about the eukaryotic V-ATPase and its subunits have been made by comparison to the structures of bacterial homologues. However, more recently, we have developed a much better understanding of the complete structure of the eukaryotic complex, in particular through advances in cryo-electron microscopy. This chapter explores these recent developments, and examines what they now reveal about the catalytic mechanism of this essential proton pump and how its activity might be regulated in response to cellular signals.
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Affiliation(s)
- Michael A Harrison
- School of Biomedical Sciences, Faculty of Biological Sciences, The University of Leeds, Leeds, UK.
| | - Steven P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, The University of Leeds, Leeds, UK
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24
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Collins MP, Forgac M. Regulation of V-ATPase Assembly in Nutrient Sensing and Function of V-ATPases in Breast Cancer Metastasis. Front Physiol 2018; 9:902. [PMID: 30057555 PMCID: PMC6053528 DOI: 10.3389/fphys.2018.00902] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 06/21/2018] [Indexed: 12/20/2022] Open
Abstract
V-ATPases are proton pumps that function to acidify intracellular compartments in all eukaryotic cells, and to transport protons across the plasma membrane of certain specialized cells. V-ATPases function in many normal and disease processes, including membrane traffic, protein degradation, pathogen entry, and cancer cell invasion. An important mechanism of regulating V-ATPase activity in vivo is regulated assembly, which is the reversible dissociation of the ATP-hydrolytic V1 domain from the proton-conducting V0 domain. Regulated assembly is highly conserved and occurs in response to various nutrient cues, suggesting that it plays an important role in cellular homeostasis. We have recently found that starvation of mammalian cells for either amino acids or glucose increases V-ATPase assembly on lysosomes, possibly to increase protein degradation (for amino acid homeostasis) or for the utilization of alternative energy sources (during glucose starvation). While regulation of assembly in response to amino acid starvation does not involve PI3K or mTORC1, glucose-regulated assembly involves both PI3K and AMPK. Another important form of V-ATPase regulation is the targeting of the enzyme to different cellular membranes, which is controlled by isoforms of subunit a. We have shown that V-ATPases are localized to the plasma membrane of highly invasive breast cancer cells, where they promote cell migration and invasion. Furthermore, overexpression of the a3 isoform is responsible for plasma membrane targeting of V-ATPases in breast tumor cells leading to their increased invasiveness.
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Affiliation(s)
- Michael P Collins
- Program in Cell, Molecular and Developmental Biology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, United States
| | - Michael Forgac
- Program in Cell, Molecular and Developmental Biology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, United States.,Department of Developmental, Molecular and Chemical Biology, School of Medicine, Tufts University, Boston, MA, United States
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25
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McGuire CM, Forgac M. Glucose starvation increases V-ATPase assembly and activity in mammalian cells through AMP kinase and phosphatidylinositide 3-kinase/Akt signaling. J Biol Chem 2018. [PMID: 29540478 DOI: 10.1074/jbc.ra117.001327] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The vacuolar H+-ATPase (V-ATPase) is an ATP-driven proton pump involved in many cellular processes. An important mechanism by which V-ATPase activity is controlled is the reversible assembly of its two domains, namely the peripheral V1 domain and the integral V0 domain. Although reversible assembly is conserved across all eukaryotic organisms, the signaling pathways controlling it have not been fully characterized. Here, we identify glucose starvation as a novel regulator of V-ATPase assembly in mammalian cells. During acute glucose starvation, the V-ATPase undergoes a rapid and reversible increase in assembly and activity as measured by lysosomal acidification. Because the V-ATPase has recently been implicated in the activation of AMP kinase (AMPK), a critical cellular energy sensor that is also activated upon glucose starvation, we compared the time course of AMPK activation and V-ATPase assembly upon glucose starvation. We observe that AMPK activation precedes increased V-ATPase activity. Moreover, the starvation-induced increase in V-ATPase activity and assembly are prevented by the AMPK inhibitor dorsomorphin. These results suggest that increased assembly and activity of the V-ATPase upon glucose starvation are dependent upon AMPK. We also find that the PI3K/Akt pathway, which has previously been implicated in controlling V-ATPase assembly in mammalian cells, also plays a role in the starvation-induced increase in V-ATPase assembly and activity. These studies thus identify a novel stimulus of V-ATPase assembly and a novel signaling pathway involved in regulating this process. The possible function of starvation-induced increase in lysosomal V-ATPase activity is discussed.
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Affiliation(s)
- Christina M McGuire
- From the Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine and the Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts 02111
| | - Michael Forgac
- From the Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine and the Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts 02111
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26
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Deprez MA, Eskes E, Wilms T, Ludovico P, Winderickx J. pH homeostasis links the nutrient sensing PKA/TORC1/Sch9 ménage-à-trois to stress tolerance and longevity. MICROBIAL CELL 2018; 5:119-136. [PMID: 29487859 PMCID: PMC5826700 DOI: 10.15698/mic2018.03.618] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The plasma membrane H+-ATPase Pma1 and the vacuolar V-ATPase act in close harmony to tightly control pH homeostasis, which is essential for a vast number of physiological processes. As these main two regulators of pH are responsive to the nutritional status of the cell, it seems evident that pH homeostasis acts in conjunction with nutrient-induced signalling pathways. Indeed, both PKA and the TORC1-Sch9 axis influence the proton pumping activity of the V-ATPase and possibly also of Pma1. In addition, it recently became clear that the proton acts as a second messenger to signal glucose availability via the V-ATPase to PKA and TORC1-Sch9. Given the prominent role of nutrient signalling in longevity, it is not surprising that pH homeostasis has been linked to ageing and longevity as well. A first indication is provided by acetic acid, whose uptake by the cell induces toxicity and affects longevity. Secondly, vacuolar acidity has been linked to autophagic processes, including mitophagy. In agreement with this, a decline in vacuolar acidity was shown to induce mitochondrial dysfunction and shorten lifespan. In addition, the asymmetric inheritance of Pma1 has been associated with replicative ageing and this again links to repercussions on vacuolar pH. Taken together, accumulating evidence indicates that pH homeostasis plays a prominent role in the determination of ageing and longevity, thereby providing new perspectives and avenues to explore the underlying molecular mechanisms.
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Affiliation(s)
| | - Elja Eskes
- Functional Biology, KU Leuven, Leuven, Belgium
| | | | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
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27
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Lim JA, Li L, Shirihai OS, Trudeau KM, Puertollano R, Raben N. Modulation of mTOR signaling as a strategy for the treatment of Pompe disease. EMBO Mol Med 2017; 9:353-370. [PMID: 28130275 PMCID: PMC5331267 DOI: 10.15252/emmm.201606547] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mechanistic target of rapamycin (mTOR) coordinates biosynthetic and catabolic processes in response to multiple extracellular and intracellular signals including growth factors and nutrients. This serine/threonine kinase has long been known as a critical regulator of muscle mass. The recent finding that the decision regarding its activation/inactivation takes place at the lysosome undeniably brings mTOR into the field of lysosomal storage diseases. In this study, we have examined the involvement of the mTOR pathway in the pathophysiology of a severe muscle wasting condition, Pompe disease, caused by excessive accumulation of lysosomal glycogen. Here, we report the dysregulation of mTOR signaling in the diseased muscle cells, and we focus on potential sites for therapeutic intervention. Reactivation of mTOR in the whole muscle of Pompe mice by TSC knockdown resulted in the reversal of atrophy and a striking removal of autophagic buildup. Of particular interest, we found that the aberrant mTOR signaling can be reversed by arginine. This finding can be translated into the clinic and may become a paradigm for targeted therapy in lysosomal, metabolic, and neuromuscular diseases.
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Affiliation(s)
- Jeong-A Lim
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA.,Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Lishu Li
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Orian S Shirihai
- Department of Medicine, Obesity and Nutrition Section, Evans Biomedical Research Center, Boston University School of Medicine, Boston, MA, USA
| | - Kyle M Trudeau
- Department of Medicine, Obesity and Nutrition Section, Evans Biomedical Research Center, Boston University School of Medicine, Boston, MA, USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Nina Raben
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
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28
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Eskes E, Deprez MA, Wilms T, Winderickx J. pH homeostasis in yeast; the phosphate perspective. Curr Genet 2017; 64:155-161. [PMID: 28856407 PMCID: PMC5778149 DOI: 10.1007/s00294-017-0743-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 08/21/2017] [Accepted: 08/22/2017] [Indexed: 12/22/2022]
Abstract
Recent research further clarified the molecular mechanisms that link nutrient signaling and pH homeostasis with the regulation of growth and survival of the budding yeast Saccharomyces cerevisiae. The central nutrient signaling kinases PKA, TORC1, and Sch9 are intimately associated to pH homeostasis, presumably allowing them to concert far-reaching phenotypical repercussions of nutritional cues. To exemplify such repercussions, we briefly describe consequences for phosphate uptake and signaling and outline interactions between phosphate homeostasis and the players involved in intra- and extracellular pH control. Inorganic phosphate uptake, its subcellular distribution, and its conversion into polyphosphates are dependent on the proton gradients created over different membranes. Conversely, polyphosphate metabolism appears to contribute in determining the intracellular pH. Additionally, inositol pyrophosphates are emerging as potent determinants of growth potential, in this way providing feedback from phosphate metabolism onto the central nutrient signaling kinases. All these data point towards the importance of phosphate metabolism in the reciprocal regulation of nutrient signaling and pH homeostasis.
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Affiliation(s)
- Elja Eskes
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium
| | - Marie-Anne Deprez
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium
| | - Tobias Wilms
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium
| | - Joris Winderickx
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium.
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29
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The yeast protein kinase Sch9 adjusts V-ATPase assembly/disassembly to control pH homeostasis and longevity in response to glucose availability. PLoS Genet 2017; 13:e1006835. [PMID: 28604780 PMCID: PMC5484544 DOI: 10.1371/journal.pgen.1006835] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 06/26/2017] [Accepted: 05/23/2017] [Indexed: 11/19/2022] Open
Abstract
The conserved protein kinase Sch9 is a central player in the nutrient-induced signaling network in yeast, although only few of its direct substrates are known. We now provide evidence that Sch9 controls the vacuolar proton pump (V-ATPase) to maintain cellular pH homeostasis and ageing. A synthetic sick phenotype arises when deletion of SCH9 is combined with a dysfunctional V-ATPase, and the lack of Sch9 has a significant impact on cytosolic pH (pHc) homeostasis. Sch9 physically interacts with, and influences glucose-dependent assembly/disassembly of the V-ATPase, thereby integrating input from TORC1. Moreover, we show that the role of Sch9 in regulating ageing is tightly connected with V-ATPase activity and vacuolar acidity. As both Sch9 and the V-ATPase are highly conserved in higher eukaryotes, it will be interesting to further clarify their cooperative action on the cellular processes that influence growth and ageing. The evolutionary conserved TOR complex 1 controls growth in response to the quality and quantity of nutrients such as carbon and amino acids. The protein kinase Sch9 is the main TORC1 effector in yeast. However, only few of its direct targets are known. In this study, we performed a genome-wide screening looking for mutants which require Sch9 function for their survival and growth. In this way, we identified multiple components of the highly conserved vacuolar proton pump (V-ATPase) which mediates the luminal acidification of multiple biosynthetic and endocytic organelles. Besides a genetic interaction, we found Sch9 also physically interacts with the V-ATPase to regulate its assembly state in response to glucose availability and TORC1 activity. Moreover, the interaction with the V-ATPase has consequences for ageing as it allowed Sch9 to control vacuolar pH and thereby trigger either lifespan extension or lifespan shortening. Hence, our results provide insights into the signaling mechanism coupling glucose availability, TORC1 signaling, pH homeostasis and longevity. As both Sch9 and the V-ATPase are highly conserved and implicated in various pathologies, these results offer fertile ground for further research in higher eukaryotes.
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30
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Liu Y, Steinbusch LKM, Nabben M, Kapsokalyvas D, van Zandvoort M, Schönleitner P, Antoons G, Simons PJ, Coumans WA, Geomini A, Chanda D, Glatz JFC, Neumann D, Luiken JJFP. Palmitate-Induced Vacuolar-Type H +-ATPase Inhibition Feeds Forward Into Insulin Resistance and Contractile Dysfunction. Diabetes 2017; 66:1521-1534. [PMID: 28302654 DOI: 10.2337/db16-0727] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 03/13/2017] [Indexed: 11/13/2022]
Abstract
Dietary fat overconsumption leads to myocardial lipid accumulation through mechanisms that are incompletely resolved. Previously, we identified increased translocation of the fatty acid transporter CD36 from its endosomal storage compartment to the sarcolemma as the primary mechanism of excessive myocellular lipid import. Here, we show that increased CD36 translocation is caused by alkalinization of endosomes resulting from inhibition of proton pumping activity of vacuolar-type H+-ATPase (v-ATPase). Endosomal alkalinization was observed in hearts from rats fed a lard-based high-fat diet and in rodent and human cardiomyocytes upon palmitate overexposure, and appeared as an early lipid-induced event preceding the onset of insulin resistance. Either genetic or pharmacological inhibition of v-ATPase in cardiomyocytes exposed to low palmitate concentrations reduced insulin sensitivity and cardiomyocyte contractility, which was rescued by CD36 silencing. The mechanism of palmitate-induced v-ATPase inhibition involved its dissociation into two parts: the cytosolic V1 and the integral membrane V0 subcomplex. Interestingly, oleate also inhibits v-ATPase function, yielding triacylglycerol accumulation but not insulin resistance. In conclusion, lipid oversupply increases CD36-mediated lipid uptake that directly impairs v-ATPase function. This feeds forward to enhanced CD36 translocation and further increased lipid uptake. In the case of palmitate, its accelerated uptake ultimately precipitates into cardiac insulin resistance and contractile dysfunction.
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Affiliation(s)
- Yilin Liu
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Laura K M Steinbusch
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Miranda Nabben
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Dimitris Kapsokalyvas
- Department of Molecular Cell Biology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Marc van Zandvoort
- Department of Molecular Cell Biology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Patrick Schönleitner
- Department of Physiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Gudrun Antoons
- Department of Physiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | | | - Will A Coumans
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Amber Geomini
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Dipanjan Chanda
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Jan F C Glatz
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Dietbert Neumann
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Joost J F P Luiken
- Department of Molecular Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
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Elsutohy MM, Chauhan VM, Markus R, Kyyaly MA, Tendler SJB, Aylott JW. Real-time measurement of the intracellular pH of yeast cells during glucose metabolism using ratiometric fluorescent nanosensors. NANOSCALE 2017; 9:5904-5911. [PMID: 28436517 DOI: 10.1039/c7nr00906b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Intracellular pH is a key parameter that influences many biochemical and metabolic pathways that can also be used as an indirect marker to monitor metabolic and intracellular processes. Herein, we utilise ratiometric fluorescent pH-sensitive nanosensors with an extended dynamic pH range to measure the intracellular pH of yeast (Saccharomyces cerevisiae) during glucose metabolism in real-time. Ratiometric fluorescent pH-sensitive nanosensors consisting of a polyacrylamide nanoparticle matrix covalently linked to two pH-sensitive fluorophores, Oregon green (OG) and 5(6)carboxyfluorescein (FAM), and a reference pH-insensitive fluorophore, 5(6)carboxytetramethylrhodamine (TAMRA), were synthesised. Nanosensors were functionalised with acrylamidopropyltrimethyl ammonium hydrochloride (ACTA) to confer a positive charge to the nanoparticle surfaces that facilitated nanosensor delivery to yeast cells, negating the need to use stress inducing techniques. The results showed that under glucose-starved conditions the intracellular pH of yeast population (n ≈ 200) was 4.67 ± 0.15. Upon addition of d-(+)-glucose (10 mM), this pH value decreased to pH 3.86 ± 0.13 over a period of 10 minutes followed by a gradual rise to a maximal pH of 5.21 ± 0.26, 25 minutes after glucose addition. 45 minutes after the addition of glucose, the intracellular pH of yeast cells returned to that of the glucose starved conditions. This study advances our understanding of the interplay between glucose metabolism and pH regulation in yeast cells, and indicates that the intracellular pH homestasis in yeast is highly regulated and demonstrates the utility of nanosensors for real-time intracellular pH measurements.
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Affiliation(s)
- Mohamed M Elsutohy
- School of Pharmacy, Boots Science Building, University of Nottingham, Nottingham, NG7 2RD, UK.
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32
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Oot RA, Couoh-Cardel S, Sharma S, Stam NJ, Wilkens S. Breaking up and making up: The secret life of the vacuolar H + -ATPase. Protein Sci 2017; 26:896-909. [PMID: 28247968 DOI: 10.1002/pro.3147] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 02/21/2017] [Indexed: 01/24/2023]
Abstract
The vacuolar ATPase (V-ATPase; V1 Vo -ATPase) is a large multisubunit proton pump found in the endomembrane system of all eukaryotic cells where it acidifies the lumen of subcellular organelles including lysosomes, endosomes, the Golgi apparatus, and clathrin-coated vesicles. V-ATPase function is essential for pH and ion homeostasis, protein trafficking, endocytosis, mechanistic target of rapamycin (mTOR), and Notch signaling, as well as hormone secretion and neurotransmitter release. V-ATPase can also be found in the plasma membrane of polarized animal cells where its proton pumping function is involved in bone remodeling, urine acidification, and sperm maturation. Aberrant (hypo or hyper) activity has been associated with numerous human diseases and the V-ATPase has therefore been recognized as a potential drug target. Recent progress with moderate to high-resolution structure determination by cryo electron microscopy and X-ray crystallography together with sophisticated single-molecule and biochemical experiments have provided a detailed picture of the structure and unique mode of regulation of the V-ATPase. This review summarizes the recent advances, focusing on the structural and biophysical aspects of the field.
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Affiliation(s)
- Rebecca A Oot
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Sergio Couoh-Cardel
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Stuti Sharma
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Nicholas J Stam
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
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33
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Chen Y, Lu Z, Chen D, Wei Y, Chen X, Huang J, Guan N, Lu Q, Wu R, Huang R. Transcriptomic analysis and driver mutant prioritization for differentially expressed genes from a Saccharomyces cerevisiae strain with high glucose tolerance generated by UV irradiation. RSC Adv 2017. [DOI: 10.1039/c7ra06146c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Driver mutations of a Saccharomyces cerevisiae mutant phenotype strain with high sugar tolerance were sought by the PheNetic network.
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Affiliation(s)
- Ying Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources
- Guangxi University
- Nanning
- P. R. China
- College of Life Science and Technology
| | - Zhilong Lu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources
- Guangxi University
- Nanning
- P. R. China
- College of Life Science and Technology
| | - Dong Chen
- National Engineering Research Center for Non-Food Biorefinery
- Guangxi Academy of Sciences
- Nanning
- P. R. China
| | - Yutuo Wei
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources
- Guangxi University
- Nanning
- P. R. China
- College of Life Science and Technology
| | - Xiaoling Chen
- National Engineering Research Center for Non-Food Biorefinery
- Guangxi Academy of Sciences
- Nanning
- P. R. China
| | - Jun Huang
- National Engineering Research Center for Non-Food Biorefinery
- Guangxi Academy of Sciences
- Nanning
- P. R. China
| | - Ni Guan
- National Engineering Research Center for Non-Food Biorefinery
- Guangxi Academy of Sciences
- Nanning
- P. R. China
| | - Qi Lu
- National Engineering Research Center for Non-Food Biorefinery
- Guangxi Academy of Sciences
- Nanning
- P. R. China
| | - Renzhi Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources
- Guangxi University
- Nanning
- P. R. China
- College of Life Science and Technology
| | - Ribo Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources
- Guangxi University
- Nanning
- P. R. China
- College of Life Science and Technology
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Carmona-Gutierrez D, Hughes AL, Madeo F, Ruckenstuhl C. The crucial impact of lysosomes in aging and longevity. Ageing Res Rev 2016; 32:2-12. [PMID: 27125853 DOI: 10.1016/j.arr.2016.04.009] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 03/26/2016] [Accepted: 04/23/2016] [Indexed: 02/07/2023]
Abstract
Lysosomes are the main catabolic organelles of a cell and play a pivotal role in a plethora of cellular processes, including responses to nutrient availability and composition, stress resistance, programmed cell death, plasma membrane repair, development, and cell differentiation. In line with this pleiotropic importance for cellular and organismal life and death, lysosomal dysfunction is associated with many age-related pathologies like Parkinson's and Alzheimer's disease, as well as with a decline in lifespan. Conversely, targeting lysosomal functional capacity is emerging as a means to promote longevity. Here, we analyze the current knowledge on the prominent influence of lysosomes on aging-related processes, such as their executory and regulatory roles during general and selective macroautophagy, or their storage capacity for amino acids and ions. In addition, we review and discuss the roles of lysosomes as active players in the mechanisms underlying known lifespan-extending interventions like, for example, spermidine or rapamycin administration. In conclusion, this review aims at critically examining the nature and pliability of the different layers, in which lysosomes are involved as a control hub for aging and longevity.
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Global Role of Cyclic AMP Signaling in pH-Dependent Responses in Candida albicans. mSphere 2016; 1:mSphere00283-16. [PMID: 27921082 PMCID: PMC5137381 DOI: 10.1128/msphere.00283-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 10/20/2016] [Indexed: 12/14/2022] Open
Abstract
Candida albicans is a human commensal and the causative agent of candidiasis, a potentially invasive and life-threatening infection. C. albicans experiences wide changes in pH during both benign commensalism (a common condition) and pathogenesis, and its morphology changes in response to this stimulus. Neutral pH is considered an activator of hyphal growth through Rim101, but the effect of low pH on other morphology-related pathways has not been extensively studied. We sought to determine the role of cyclic AMP signaling, a central regulator of morphology, in the sensing of pH. In addition, we asked broadly what cellular processes were altered by pH in both the presence and absence of this important signal integration system. We concluded that cAMP signaling is impacted by pH and that cAMP broadly impacts C. albicans physiology in both pH-dependent and -independent ways. Candida albicans behaviors are affected by pH, an important environmental variable. Filamentous growth is a pH-responsive behavior, where alkaline conditions favor hyphal growth and acid conditions favor growth as yeast. We employed filamentous growth as a tool to study the impact of pH on the hyphal growth regulator Cyr1, and we report that downregulation of cyclic AMP (cAMP) signaling by acidic pH contributes to the inhibition of hyphal growth in minimal medium with GlcNAc. Ras1 and Cyr1 are generally required for efficient hyphal growth, and the effects of low pH on Ras1 proteolysis and GTP binding are consistent with diminished cAMP output. Active alleles of ras1 do not suppress the hyphal growth defect at low pH, while dibutyryl cAMP partially rescues filamentous growth at low pH in a cyr1 mutant. These observations are consistent with Ras1-independent downregulation of Cyr1 by low pH. We also report that extracellular pH leads to rapid and prolonged decreases in intracellular pH, and these changes may contribute to reduced cAMP signaling by reducing intracellular bicarbonate pools. Transcriptomics analyses found that the loss of Cyr1 at either acidic or neutral pH leads to increases in transcripts involved in carbohydrate catabolism and protein translation and glycosylation and decreases in transcripts involved in oxidative metabolism, fluconazole transport, metal transport, and biofilm formation. Other pathways were modulated in pH-dependent ways. Our findings indicate that cAMP has a global role in pH-dependent responses, and this effect is mediated, at least in part, through Cyr1 in a Ras1-independent fashion. IMPORTANCECandida albicans is a human commensal and the causative agent of candidiasis, a potentially invasive and life-threatening infection. C. albicans experiences wide changes in pH during both benign commensalism (a common condition) and pathogenesis, and its morphology changes in response to this stimulus. Neutral pH is considered an activator of hyphal growth through Rim101, but the effect of low pH on other morphology-related pathways has not been extensively studied. We sought to determine the role of cyclic AMP signaling, a central regulator of morphology, in the sensing of pH. In addition, we asked broadly what cellular processes were altered by pH in both the presence and absence of this important signal integration system. We concluded that cAMP signaling is impacted by pH and that cAMP broadly impacts C. albicans physiology in both pH-dependent and -independent ways.
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Chan CY, Dominguez D, Parra KJ. Regulation of Vacuolar H+-ATPase (V-ATPase) Reassembly by Glycolysis Flow in 6-Phosphofructo-1-kinase (PFK-1)-deficient Yeast Cells. J Biol Chem 2016; 291:15820-9. [PMID: 27226568 DOI: 10.1074/jbc.m116.717488] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 01/21/2023] Open
Abstract
Yeast 6-phosphofructo-1-kinase (PFK-1) has two subunits, Pfk1p and Pfk2p. Deletion of Pfk2p alters glucose-dependent V-ATPase reassembly and vacuolar acidification (Chan, C. Y., and Parra, K. J. (2014) Yeast phosphofructokinase-1 subunit Pfk2p is necessary for pH homeostasis and glucose-dependent vacuolar ATPase reassembly. J. Biol. Chem. 289, 19448-19457). This study capitalized on the mechanisms suppressing vacuolar H(+)-ATPase (V-ATPase) in pfk2Δ to gain new knowledge of the mechanisms underlying glucose-dependent V-ATPase regulation. Because V-ATPase is fully assembled in pfk2Δ, and glycolysis partially suppressed at steady state, we manipulated glycolysis and assessed its direct involvement on V-ATPase function. At steady state, the ratio of proton transport to ATP hydrolysis increased 24% after increasing the glucose concentration from 2% to 4% to enhance the glycolysis flow in pfk2Δ. Tighter coupling restored vacuolar pH when glucose was abundant and glycolysis operated below capacity. After readdition of glucose to glucose-deprived cells, glucose-dependent V1Vo reassembly was proportional to the glycolysis flow. Readdition of 2% glucose to pfk2Δ cells, which restored 62% of ethanol concentration, led to equivalent 60% V1Vo reassembly levels. Steady-state level of assembly (100% reassembly) was reached at 4% glucose when glycolysis reached a threshold in pfk2Δ (≥40% the wild-type flow). At 4% glucose, the level of Pfk1p co-immunoprecipitated with V-ATPase decreased 58% in pfk2Δ, suggesting that Pfk1p binding to V-ATPase may be inhibitory in the mutant. We concluded that V-ATPase activity at steady state and V-ATPase reassembly after readdition of glucose to glucose-deprived cells are controlled by the glycolysis flow. We propose a new mechanism by which glucose regulates V-ATPase catalytic activity that occurs at steady state without changing V1Vo assembly.
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Affiliation(s)
- Chun-Yuan Chan
- From the Department of Biochemistry and Molecular Biology, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131
| | - Dennis Dominguez
- From the Department of Biochemistry and Molecular Biology, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131
| | - Karlett J Parra
- From the Department of Biochemistry and Molecular Biology, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131
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Cotter K, Stransky L, McGuire C, Forgac M. Recent Insights into the Structure, Regulation, and Function of the V-ATPases. Trends Biochem Sci 2016; 40:611-622. [PMID: 26410601 DOI: 10.1016/j.tibs.2015.08.005] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 08/06/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
The vacuolar (H(+))-ATPases (V-ATPases) are ATP-dependent proton pumps that acidify intracellular compartments and are also present at the plasma membrane. They function in such processes as membrane traffic, protein degradation, virus and toxin entry, bone resorption, pH homeostasis, and tumor cell invasion. V-ATPases are large multisubunit complexes, composed of an ATP-hydrolytic domain (V1) and a proton translocation domain (V0), and operate by a rotary mechanism. This review focuses on recent insights into their structure and mechanism, the mechanisms that regulate V-ATPase activity (particularly regulated assembly and trafficking), and the role of V-ATPases in processes such as cell signaling and cancer. These developments have highlighted the potential of V-ATPases as a therapeutic target in a variety of human diseases.
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Affiliation(s)
- Kristina Cotter
- Program in Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Laura Stransky
- Program in Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Christina McGuire
- Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Michael Forgac
- Program in Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA; Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA; Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
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McGuire C, Cotter K, Stransky L, Forgac M. Regulation of V-ATPase assembly and function of V-ATPases in tumor cell invasiveness. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1213-1218. [PMID: 26906430 DOI: 10.1016/j.bbabio.2016.02.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 02/04/2023]
Abstract
V-ATPases are ATP-driven proton pumps that function within both intracellular compartments and the plasma membrane in a wide array of normal physiological and pathophysiological processes. V-ATPases are composed of a peripheral V(1) domain that hydrolyzes ATP and an integral V(0) domain that transports protons. Regulated assembly of the V-ATPase represents an important mechanism of regulating V-ATPase activity in response to a number of environmental cues. Our laboratory has demonstrated that glucose-dependent assembly of the V-ATPase complex in yeast is controlled by the Ras/cAMP/PKA pathway. By contrast, increased assembly of the V-ATPase during dendritic cell maturation involves the PI-3 kinase and mTORC1 pathways. Recently, we have shown that amino acids regulate V-ATPase assembly in mammalian cells, possibly as a means to maintain adequate levels of amino acids upon nutrient starvation. V-ATPases have also been implicated in cancer cell survival and invasion. V-ATPases are targeted to different cellular membranes by isoforms of subunit a, with a3 targeting V-ATPases to the plasma membrane of osteoclasts. We have shown that highly invasive human breast cancer cell lines express higher levels of the a3 isoform than poorly invasive lines and that knockdown of a3 reduces both expression of V-ATPases at the plasma membrane and in vitro invasion of breast tumor cells. Moreover, overexpression of a3 in a non-invasive breast epithelial line increases both plasma membrane V-ATPases and in vitro invasion. Finally, specific ablation of plasma membrane V-ATPases in highly invasive human breast cancer cells using either an antibody or small molecule approach inhibits both in vitro invasion and migration. These results suggest that plasma membrane and a3-containing V-ATPases represent a novel and important target in the development of therapeutics to limit breast cancer metastasis. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Christina McGuire
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, United States
| | - Kristina Cotter
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, United States
| | - Laura Stransky
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, United States
| | - Michael Forgac
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, United States
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Akdoğan E, Tardu M, Garipler G, Baytek G, Kavakli İH, Dunn CD. Reduced Glucose Sensation Can Increase the Fitness of Saccharomyces cerevisiae Lacking Mitochondrial DNA. PLoS One 2016; 11:e0146511. [PMID: 26751567 PMCID: PMC4709096 DOI: 10.1371/journal.pone.0146511] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 12/19/2015] [Indexed: 12/12/2022] Open
Abstract
Damage to the mitochondrial genome (mtDNA) can lead to diseases for which there are no clearly effective treatments. Since mitochondrial function and biogenesis are controlled by the nutrient environment of the cell, it is possible that perturbation of conserved, nutrient-sensing pathways may successfully treat mitochondrial disease. We found that restricting glucose or otherwise reducing the activity of the protein kinase A (PKA) pathway can lead to improved proliferation of Saccharomyces cerevisiae cells lacking mtDNA and that the transcriptional response to mtDNA loss is reduced in cells with diminished PKA activity. We have excluded many pathways and proteins from being individually responsible for the benefits provided to cells lacking mtDNA by PKA inhibition, and we found that robust import of mitochondrial polytopic membrane proteins may be required in order for cells without mtDNA to receive the full benefits of PKA reduction. Finally, we have discovered that the transcription of genes involved in arginine biosynthesis and aromatic amino acid catabolism is altered after mtDNA damage. Our results highlight the potential importance of nutrient detection and availability on the outcome of mitochondrial dysfunction.
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Affiliation(s)
- Emel Akdoğan
- Department of Molecular Biology and Genetics, Koç University, Sarıyer, İstanbul, 34450, Turkey
| | - Mehmet Tardu
- Department of Chemical and Biological Engineering, Koç University, Sarıyer, İstanbul, 34450, Turkey
| | - Görkem Garipler
- Department of Molecular Biology and Genetics, Koç University, Sarıyer, İstanbul, 34450, Turkey
| | - Gülkız Baytek
- Department of Molecular Biology and Genetics, Koç University, Sarıyer, İstanbul, 34450, Turkey
| | - İ. Halil Kavakli
- Department of Molecular Biology and Genetics, Koç University, Sarıyer, İstanbul, 34450, Turkey
- Department of Chemical and Biological Engineering, Koç University, Sarıyer, İstanbul, 34450, Turkey
| | - Cory D. Dunn
- Department of Molecular Biology and Genetics, Koç University, Sarıyer, İstanbul, 34450, Turkey
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Abstract
Despite diverse and changing extracellular environments, fungi maintain a relatively constant cytosolic pH and numerous organelles of distinct lumenal pH. Key players in fungal pH control are V-ATPases and the P-type proton pump Pma1. These two proton pumps act in concert with a large array of other transporters and are highly regulated. The activities of Pma1 and the V-ATPase are coordinated under some conditions, suggesting that pH in the cytosol and organelles is not controlled independently. Genomic studies, particularly in the highly tractable S. cerevisiae, are beginning to provide a systems-level view of pH control, including transcriptional responses to acid or alkaline ambient pH and definition of the full set of regulators required to maintain pH homeostasis. Genetically encoded pH sensors have provided new insights into localized mechanisms of pH control, as well as highlighting the dynamic nature of pH responses to the extracellular environment. Recent studies indicate that cellular pH plays a genuine signaling role that connects nutrient availability and growth rate through a number of mechanisms. Many of the pH control mechanisms found in S. cerevisiae are shared with other fungi, with adaptations for their individual physiological contexts. Fungi deploy certain proton transport and pH control mechanisms not shared with other eukaryotes; these regulators of cellular pH are potential antifungal targets. This review describes current and emerging knowledge proton transport and pH control mechanisms in S. cerevisiae and briefly discusses how these mechanisms vary among fungi.
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Jia C, Yu Q, Xu N, Zhang B, Dong Y, Ding X, Chen Y, Zhang B, Xing L, Li M. Role of TFP1 in vacuolar acidification, oxidative stress and filamentous development in Candida albicans. Fungal Genet Biol 2014; 71:58-67. [PMID: 25220074 DOI: 10.1016/j.fgb.2014.08.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/21/2014] [Accepted: 08/25/2014] [Indexed: 10/24/2022]
Abstract
The vacuolar-type H(+)-ATPase (V-ATPase) is a multiprotein complex consisting of the V0 and V1 sectors, and is required for vacuolar acidification and virulence in the opportunistic fungal pathogen Candida albicans. In this study, we identified C. albicans Tfp1 as a putative subunit of V-ATPase, and explored its importance in multiple cellular processes. Our results revealed that Tfp1 played an essential role in vacuolar acidification and endocytic trafficking. In addition, the tfp1Δ/Δ mutant was sensitive to alkaline pH and elevated calcium concentrations, which is characteristic of loss of V-ATPase activity. The mutant also showed hypersensitivity to metal ions which might be attributed to a defect in sequestration of toxic ions to the vacuole through proton gradient produced by V-ATPase. Interestingly, deletion of TFP1 triggered endogenous oxidative stress even without exogenous oxidants. Compared with the wild-type strain, the tfp1Δ/Δ mutant showed significantly higher ROS levels and lower expression levels of redox-related genes with the addition of hydrogen peroxide (H2O2). Western blotting analysis showed that deletion of TFP1 significantly reduced the expression of Cap1 under H2O2 treatment, which contributes to the regulation of genes involved in the oxidative stress response. Furthermore, the tfp1Δ/Δ mutant showed significantly impaired filamentous development in hyphal induction media, and was avirulent in a mouse model of systemic candidiasis. Taken together, our results suggested that the putative V1 subunit Tfp1 is essential for vacuolar function and C. albicans pathogenesis, and provided a promising candidate for antifungal drugs.
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Affiliation(s)
- Chang Jia
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Ning Xu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Yijie Dong
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Xiaohui Ding
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Yulu Chen
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Biao Zhang
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
| | - Laijun Xing
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China.
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Davies SA, Cabrero P, Overend G, Aitchison L, Sebastian S, Terhzaz S, Dow JAT. Cell signalling mechanisms for insect stress tolerance. ACTA ACUST UNITED AC 2014; 217:119-28. [PMID: 24353211 DOI: 10.1242/jeb.090571] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insects successfully occupy most environmental niches and this success depends on surviving a broad range of environmental stressors including temperature, desiccation, xenobiotic, osmotic and infection stress. Epithelial tissues play key roles as barriers between the external and internal environments and therefore maintain homeostasis and organismal tolerance to multiple stressors. As such, the crucial role of epithelia in organismal stress tolerance cannot be underestimated. At a molecular level, multiple cell-specific signalling pathways including cyclic cAMP, cyclic cGMP and calcium modulate tissue, and hence, organismal responses to stress. Thus, epithelial cell-specific signal transduction can be usefully studied to determine the molecular mechanisms of organismal stress tolerance in vivo. This review will explore cell signalling modulation of stress tolerance in insects by focusing on cell signalling in a fluid transporting epithelium--the Malpighian tubule. Manipulation of specific genes and signalling pathways in only defined tubule cell types can influence the survival outcome in response to multiple environmental stressors including desiccation, immune, salt (ionic) and oxidative stress, suggesting that studies in the genetic model Drosophila melanogaster may reveal novel pathways required for stress tolerance.
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Affiliation(s)
- Shireen A Davies
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Chan CY, Parra KJ. Yeast phosphofructokinase-1 subunit Pfk2p is necessary for pH homeostasis and glucose-dependent vacuolar ATPase reassembly. J Biol Chem 2014; 289:19448-57. [PMID: 24860096 DOI: 10.1074/jbc.m114.569855] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
V-ATPases are conserved ATP-driven proton pumps that acidify organelles. Yeast V-ATPase assembly and activity are glucose-dependent. Glucose depletion causes V-ATPase disassembly and its inactivation. Glucose readdition triggers reassembly and resumes proton transport and organelle acidification. We investigated the roles of the yeast phosphofructokinase-1 subunits Pfk1p and Pfk2p for V-ATPase function. The pfk1Δ and pfk2Δ mutants grew on glucose and assembled wild-type levels of V-ATPase pumps at the membrane. Both phosphofructokinase-1 subunits co-immunoprecipitated with V-ATPase in wild-type cells; upon deletion of one subunit, the other subunit retained binding to V-ATPase. The pfk2Δ cells exhibited a partial vma growth phenotype. In vitro ATP hydrolysis and proton transport were reduced by 35% in pfk2Δ membrane fractions; they were normal in pfk1Δ. In vivo, the pfk1Δ and pfk2Δ vacuoles were alkalinized and the cytosol acidified, suggestive of impaired V-ATPase proton transport. Overall the pH alterations were more dramatic in pfk2Δ than pfk1Δ at steady state and after readdition of glucose to glucose-deprived cells. Glucose-dependent reassembly was 50% reduced in pfk2Δ, and the vacuolar lumen was not acidified after reassembly. RAVE-assisted glucose-dependent reassembly and/or glucose signals were disturbed in pfk2Δ. Binding of disassembled V-ATPase (V1 domain) to its assembly factor RAVE (subunit Rav1p) was 5-fold enhanced, indicating that Pfk2p is necessary for V-ATPase regulation by glucose. Because Pfk1p and Pfk2p are necessary for V-ATPase proton transport at the vacuole in vivo, a role for glycolysis at regulating V-ATPase proton transport is discussed.
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Affiliation(s)
- Chun-Yuan Chan
- From the Department of Biochemistry and Molecular Biology of the School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131
| | - Karlett J Parra
- From the Department of Biochemistry and Molecular Biology of the School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131
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Saccharomyces cerevisiae vacuolar H+-ATPase regulation by disassembly and reassembly: one structure and multiple signals. EUKARYOTIC CELL 2014; 13:706-14. [PMID: 24706019 DOI: 10.1128/ec.00050-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Vacuolar H(+)-ATPases (V-ATPases) are highly conserved ATP-driven proton pumps responsible for acidification of intracellular compartments. V-ATPase proton transport energizes secondary transport systems and is essential for lysosomal/vacuolar and endosomal functions. These dynamic molecular motors are composed of multiple subunits regulated in part by reversible disassembly, which reversibly inactivates them. Reversible disassembly is intertwined with glycolysis, the RAS/cyclic AMP (cAMP)/protein kinase A (PKA) pathway, and phosphoinositides, but the mechanisms involved are elusive. The atomic- and pseudo-atomic-resolution structures of the V-ATPases are shedding light on the molecular dynamics that regulate V-ATPase assembly. Although all eukaryotic V-ATPases may be built with an inherent capacity to reversibly disassemble, not all do so. V-ATPase subunit isoforms and their interactions with membrane lipids and a V-ATPase-exclusive chaperone influence V-ATPase assembly. This minireview reports on the mechanisms governing reversible disassembly in the yeast Saccharomyces cerevisiae, keeping in perspective our present understanding of the V-ATPase architecture and its alignment with the cellular processes and signals involved.
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Marshansky V, Rubinstein JL, Grüber G. Eukaryotic V-ATPase: novel structural findings and functional insights. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:857-79. [PMID: 24508215 DOI: 10.1016/j.bbabio.2014.01.018] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 12/25/2013] [Accepted: 01/27/2014] [Indexed: 02/06/2023]
Abstract
The eukaryotic V-type adenosine triphosphatase (V-ATPase) is a multi-subunit membrane protein complex that is evolutionarily related to F-type adenosine triphosphate (ATP) synthases and A-ATP synthases. These ATPases/ATP synthases are functionally conserved and operate as rotary proton-pumping nano-motors, invented by Nature billions of years ago. In the first part of this review we will focus on recent structural findings of eukaryotic V-ATPases and discuss the role of different subunits in the function of the V-ATPase holocomplex. Despite structural and functional similarities between rotary ATPases, the eukaryotic V-ATPases are the most complex enzymes that have acquired some unconventional cellular functions during evolution. In particular, the novel roles of V-ATPases in the regulation of cellular receptors and their trafficking via endocytotic and exocytotic pathways were recently uncovered. In the second part of this review we will discuss these unique roles of V-ATPases in modulation of function of cellular receptors, involved in the development and progression of diseases such as cancer and diabetes as well as neurodegenerative and kidney disorders. Moreover, it was recently revealed that the V-ATPase itself functions as an evolutionarily conserved pH sensor and receptor for cytohesin-2/Arf-family GTP-binding proteins. Thus, in the third part of the review we will evaluate the structural basis for and functional insights into this novel concept, followed by the analysis of the potentially essential role of V-ATPase in the regulation of this signaling pathway in health and disease. Finally, future prospects for structural and functional studies of the eukaryotic V-ATPase will be discussed.
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Affiliation(s)
- Vladimir Marshansky
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Simches Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Medicine, Harvard Medical School, Boston, MA 02114, USA; Kadmon Pharmaceuticals Corporation, Alexandria Center for Life Science, 450 East 29th Street, New York, NY 10016, USA.
| | - John L Rubinstein
- Molecular Structure and Function Program, The Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1X8, Canada
| | - Gerhard Grüber
- Nanyang Technological University, Division of Structural Biology and Biochemistry, School of Biological Sciences, Singapore 637551, Republic of Singapore; Bioinformatics Institute, A(⁎)STAR, 60 Nanyang Drive, Singapore 637551, Republic of Singapore
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Molin M, Demir AB. Linking Peroxiredoxin and Vacuolar-ATPase Functions in Calorie Restriction-Mediated Life Span Extension. Int J Cell Biol 2014; 2014:913071. [PMID: 24639875 PMCID: PMC3930189 DOI: 10.1155/2014/913071] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/11/2013] [Accepted: 12/15/2013] [Indexed: 01/09/2023] Open
Abstract
Calorie restriction (CR) is an intervention extending the life spans of many organisms. The mechanisms underlying CR-dependent retardation of aging are still poorly understood. Despite mechanisms involving conserved nutrient signaling pathways proposed, few target processes that can account for CR-mediated longevity have so far been identified. Recently, both peroxiredoxins and vacuolar-ATPases were reported to control CR-mediated retardation of aging downstream of conserved nutrient signaling pathways. In this review, we focus on peroxiredoxin-mediated stress-defence and vacuolar-ATPase regulated acidification and pinpoint common denominators between the two mechanisms proposed for how CR extends life span. Both the activities of peroxiredoxins and vacuolar-ATPases are stimulated upon CR through reduced activities in conserved nutrient signaling pathways and both seem to stimulate cellular resistance to peroxide-stress. However, whereas vacuolar-ATPases have recently been suggested to control both Ras-cAMP-PKA- and TORC1-mediated nutrient signaling, neither the physiological benefits of a proposed role for peroxiredoxins in H2O2-signaling nor downstream targets regulated are known. Both peroxiredoxins and vacuolar-ATPases do, however, impinge on mitochondrial iron-metabolism and further characterization of their impact on iron homeostasis and peroxide-resistance might therefore increase our understanding of the beneficial effects of CR on aging and age-related diseases.
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Affiliation(s)
- Mikael Molin
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Gothenburg, Sweden
| | - Ayse Banu Demir
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Gothenburg, Sweden
- Department of Molecular Biology and Genetics, Izmir Institute of Technology, 35430 Urla, Izmir, Turkey
- Department of Oncology, Institute of Oncology, Dokuz Eylul University, 35340 Inciralti, Izmir, Turkey
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Flexibility within the rotor and stators of the vacuolar H+-ATPase. PLoS One 2013; 8:e82207. [PMID: 24312643 PMCID: PMC3846802 DOI: 10.1371/journal.pone.0082207] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/21/2013] [Indexed: 11/19/2022] Open
Abstract
The V-ATPase is a membrane-bound protein complex which pumps protons across the membrane to generate a large proton motive force through the coupling of an ATP-driven 3-stroke rotary motor (V1) to a multistroke proton pump (Vo). This is done with near 100% efficiency, which is achieved in part by flexibility within the central rotor axle and stator connections, allowing the system to flex to minimise the free energy loss of conformational changes during catalysis. We have used electron microscopy to reveal distinctive bending along the V-ATPase complex, leading to angular displacement of the V1 domain relative to the Vo domain to a maximum of ~30°. This has been complemented by elastic network normal mode analysis that shows both flexing and twisting with the compliance being located in the rotor axle, stator filaments, or both. This study provides direct evidence of flexibility within the V-ATPase and by implication in related rotary ATPases, a feature predicted to be important for regulation and their high energetic efficiencies.
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Muench SP, Scheres SHW, Huss M, Phillips C, Vitavska O, Wieczorek H, Trinick J, Harrison MA. Subunit positioning and stator filament stiffness in regulation and power transmission in the V1 motor of the Manduca sexta V-ATPase. J Mol Biol 2013; 426:286-300. [PMID: 24075871 PMCID: PMC3899036 DOI: 10.1016/j.jmb.2013.09.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 12/01/2022]
Abstract
The vacuolar H+-ATPase (V-ATPase) is an ATP-driven proton pump essential to the function of eukaryotic cells. Its cytoplasmic V1 domain is an ATPase, normally coupled to membrane-bound proton pump Vo via a rotary mechanism. How these asymmetric motors are coupled remains poorly understood. Low energy status can trigger release of V1 from the membrane and curtail ATP hydrolysis. To investigate the molecular basis for these processes, we have carried out cryo-electron microscopy three-dimensional reconstruction of deactivated V1 from Manduca sexta. In the resulting model, three peripheral stalks that are parts of the mechanical stator of the V-ATPase are clearly resolved as unsupported filaments in the same conformations as in the holoenzyme. They are likely therefore to have inherent stiffness consistent with a role as flexible rods in buffering elastic power transmission between the domains of the V-ATPase. Inactivated V1 adopted a homogeneous resting state with one open active site adjacent to the stator filament normally linked to the H subunit. Although present at 1:1 stoichiometry with V1, both recombinant subunit C reconstituted with V1 and its endogenous subunit H were poorly resolved in three-dimensional reconstructions, suggesting structural heterogeneity in the region at the base of V1 that could indicate positional variability. If the position of H can vary, existing mechanistic models of deactivation in which it binds to and locks the axle of the V-ATPase rotary motor would need to be re-evaluated. Dissociation of vacuolar H+-ATPase domains deactivates its V1 motor. V1 has one “open” catalytic site linked to the stator filament bound by subunit H. Movement of subunit H to prevent rotary catalysis is possible. Three stator filaments project from deactivated V1, indicating inherent stiffness. This work gives new insight into energetic coupling and control in V-ATPases.
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Affiliation(s)
- Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Sjors H W Scheres
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Markus Huss
- Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany
| | - Clair Phillips
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Olga Vitavska
- Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany
| | - Helmut Wieczorek
- Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany
| | - John Trinick
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Michael A Harrison
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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Ribeiro CC, Monteiro RM, Freitas FP, Retamal C, Teixeira LRS, Palma LM, Silva FE, Façanha AR, Okorokova-Façanha AL, Okorokov LA. Extracellular glucose increases the coupling capacity of the yeast V H+-ATPase and the resistance of its H+ transport activity to nitrate inhibition. PLoS One 2012; 7:e49580. [PMID: 23189149 PMCID: PMC3506656 DOI: 10.1371/journal.pone.0049580] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 10/11/2012] [Indexed: 11/18/2022] Open
Abstract
V H(+)-ATPase has an important role in a variety of key physiological processes. This enzyme is reversibly activated/partly inactivated by the addition/exhaustion of extracellular glucose. The current model of its regulation assumes the reversible disassembly/reassembly of ∼60-70% of the V1 and V0 membrane complexes, which are responsible for ATP hydrolysis and H(+) conductance, respectively. The number of assembled complexes determines the pump activity because disassembled complexes are inactive. The model predicts the identical catalytic properties for the activated and semi-active enzymes molecules. To verify the model predictions we have isolated total membranes from yeast spheroplasts that were pre-incubated either with or without glucose. Nitrate treatment of membranes revealed the similar ATPase inhibition for two enzyme states, suggesting that they have identical structures that are essential for ATP hydrolysis. However, H(+) transport was inhibited more than the ATPase activities, indicating a nitrate uncoupling action, which was significantly higher for the nonactivated enzyme. This finding suggests that the structure of the non-activated enzyme, which is essential for H(+) transport, is less stable than that of the activated enzyme. Moreover, the glucose activation of the pump increases i) its coupling capacity; ii) its K(M) for ATP hydrolysis and ATP affinity for H(+) transport; iii) the Vmax for H(+) transport in comparison with the Vmax for ATP hydrolysis and iv) the immune reactivity of catalytic subunit A and regulatory subunit B by 9.3 and 2.4 times, respectively. The protein content of subunits A and B was not changed by extracellular glucose. We propose that instead of the dissociation/reassociation of complexes V1 and V0, changes in the extracellular glucose concentration cause reversible and asymmetrical modulations in the immune reactivity of subunits A and B by their putative biochemical modifications. This response asymmetrically modulates H(+)-transport and ATP hydrolysis, exhibiting distinct properties for the activated versus non-activated enzymes.
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Affiliation(s)
- Camila C. Ribeiro
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
- Laboratório de Biologia Celular e Tecidual, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Renan M. Monteiro
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Flavia P. Freitas
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Claudio Retamal
- Laboratório de Biologia Celular e Tecidual, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Layz R. S. Teixeira
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Livia M. Palma
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Flavia E. Silva
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Arnoldo R. Façanha
- Laboratório de Biologia Celular e Tecidual, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Anna L. Okorokova-Façanha
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
| | - Lev A. Okorokov
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brasil
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50
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Parsons LS, Wilkens S. Probing subunit-subunit interactions in the yeast vacuolar ATPase by peptide arrays. PLoS One 2012; 7:e46960. [PMID: 23071676 PMCID: PMC3470569 DOI: 10.1371/journal.pone.0046960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 09/07/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Vacuolar (H(+))-ATPase (V-ATPase; V(1)V(o)-ATPase) is a large multisubunit enzyme complex found in the endomembrane system of all eukaryotic cells where its proton pumping action serves to acidify subcellular organelles. In the plasma membrane of certain specialized tissues, V-ATPase functions to pump protons from the cytoplasm into the extracellular space. The activity of the V-ATPase is regulated by a reversible dissociation mechanism that involves breaking and re-forming of protein-protein interactions in the V(1)-ATPase - V(o)-proton channel interface. The mechanism responsible for regulated V-ATPase dissociation is poorly understood, largely due to a lack of detailed knowledge of the molecular interactions that are responsible for the structural and functional link between the soluble ATPase and membrane bound proton channel domains. METHODOLOGY/PRINCIPAL FINDINGS To gain insight into where some of the stator subunits of the V-ATPase associate with each other, we have developed peptide arrays from the primary sequences of V-ATPase subunits. By probing the peptide arrays with individually expressed V-ATPase subunits, we have identified several key interactions involving stator subunits E, G, C, H and the N-terminal domain of the membrane bound a subunit. CONCLUSIONS The subunit-peptide interactions identified from the peptide arrays complement low resolution structural models of the eukaryotic vacuolar ATPase obtained from transmission electron microscopy. The subunit-subunit interaction data are discussed in context of our current model of reversible enzyme dissociation.
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Affiliation(s)
- Lee S. Parsons
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States of America
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