1
|
Wang R, Qin Y, Xie XS, Li X. Molecular basis of mEAK7-mediated human V-ATPase regulation. Nat Commun 2022; 13:3272. [PMID: 35672408 PMCID: PMC9174246 DOI: 10.1038/s41467-022-30899-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 05/24/2022] [Indexed: 11/09/2022] Open
Abstract
The activity of V-ATPase is well-known to be regulated by reversible dissociation of its V1 and Vo domains in response to growth factor stimulation, nutrient sensing, and cellular differentiation. The molecular basis of its regulation by an endogenous modulator without affecting V-ATPase assembly remains unclear. Here, we discover that a lysosome-anchored protein termed (mammalian Enhancer-of-Akt-1-7 (mEAK7)) binds to intact V-ATPase. We determine cryo-EM structure of human mEAK7 in complex with human V-ATPase in native lipid-containing nanodiscs. The structure reveals that the TLDc domain of mEAK7 engages with subunits A, B, and E, while its C-terminal domain binds to subunit D, presumably blocking V1-Vo torque transmission. Our functional studies suggest that mEAK7, which may act as a V-ATPase inhibitor, does not affect the activity of V-ATPase in vitro. However, overexpression of mEAK7 in HCT116 cells that stably express subunit a4 of V-ATPase represses the phosphorylation of ribosomal protein S6. Thus, this finding suggests that mEAK7 potentially links mTOR signaling with V-ATPase activity.
Collapse
Affiliation(s)
- Rong Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Yu Qin
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Xiao-Song Xie
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Xiaochun Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
2
|
Wang R, Long T, Hassan A, Wang J, Sun Y, Xie XS, Li X. Cryo-EM structures of intact V-ATPase from bovine brain. Nat Commun 2020; 11:3921. [PMID: 32764564 PMCID: PMC7414150 DOI: 10.1038/s41467-020-17762-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 07/17/2020] [Indexed: 12/12/2022] Open
Abstract
The vacuolar-type H+-ATPases (V-ATPase) hydrolyze ATP to pump protons across the plasma or intracellular membrane, secreting acids to the lumen or acidifying intracellular compartments. It has been implicated in tumor metastasis, renal tubular acidosis, and osteoporosis. Here, we report two cryo-EM structures of the intact V-ATPase from bovine brain with all the subunits including the subunit H, which is essential for ATPase activity. Two type-I transmembrane proteins, Ac45 and (pro)renin receptor, along with subunit c", constitute the core of the c-ring. Three different conformations of A/B heterodimers suggest a mechanism for ATP hydrolysis that triggers a rotation of subunits DF, inducing spinning of subunit d with respect to the entire c-ring. Moreover, many lipid molecules have been observed in the Vo domain to mediate the interactions between subunit c, c", (pro)renin receptor, and Ac45. These two structures reveal unique features of mammalian V-ATPase and suggest a mechanism of V1-Vo torque transmission.
Collapse
Affiliation(s)
- Rong Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Tao Long
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Abdirahman Hassan
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jin Wang
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Yingyuan Sun
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Xiao-Song Xie
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Xiaochun Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA. .,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
3
|
Jeong YD, Park YJ, Ko YG, Lee SS, Lee SH, Lee J, Kim KW, Kim SW, Kim B. Development and Differentiation of Epididymal Epithelial Cells in Korean Native Black Goat. Animals (Basel) 2020; 10:ani10081273. [PMID: 32722459 PMCID: PMC7459902 DOI: 10.3390/ani10081273] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/14/2020] [Accepted: 07/23/2020] [Indexed: 01/08/2023] Open
Abstract
Simple Summary Studies have revealed that the communication networks among epididymal epithelial cells play an essential role in sperm maturation and storage. Therefore, the localization and expression of V-ATPase and cytokeratin 5 in the clear cells and basal cells, respectively, of immature and mature goat epididymis was investigated. To the best of our knowledge, the present study is the first to use immunofluorescence labeling and confocal imaging to characterize the differentiation of clear cells and basal cells in the goat epididymis. The findings could help the understanding of the regulatory mechanism that creates an optimal luminal environment for sperm maturation and storage in the epididymis. Abstract The acidic luminal environment of the epididymis is regulated by the communication networks among epididymal epithelial cells; it is necessary for sperm maturation and storage. To characterize epididymal epithelial cell differentiation, the localization and expression of hydrogen-pumping vacuolar ATPase (V-ATPase) and cytokeratin 5 (KRT5) in the clear and basal cells, respectively, of immature and mature goat epididymis and vas deferens was examined. The epididymides and vas deferens were obtained from goats aged 1, 2, and 12–14 months. To assess the localization and expression patterns of V-ATPase and KRT5 in the caput, corpus, and cauda of the epididymis and proximal vas deferens, the tissue sections were subjected to immunofluorescence labeling and observed by confocal microscopy. Both clear and basal cells progressively started to differentiate in a retrograde manner. Clear cells disappeared from the cauda region after puberty, and they were maintained only in the caput and corpus regions of the adult goat epididymis. V-ATPase and KRT5 were co-expressed in the differentiated cells located at the base of the epithelium (i.e., basal cells). This cell type-specific differentiation and distribution of the epithelial cells plays a critical role in establishing a unique luminal environment for sperm maturation and storage in the goat epididymis.
Collapse
Affiliation(s)
- Yu-Da Jeong
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea; (Y.-D.J.); (Y.-J.P.)
| | - Yun-Jae Park
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea; (Y.-D.J.); (Y.-J.P.)
| | - Yeoung-Gyu Ko
- Animal Genetic Resource Research Center, National Institute of Animal Science, RDA, Hamyang 50000, Korea; (Y.-G.K.); (S.-S.L.); (S.-H.L.); (J.L.); (K.-W.K.)
| | - Sung-Soo Lee
- Animal Genetic Resource Research Center, National Institute of Animal Science, RDA, Hamyang 50000, Korea; (Y.-G.K.); (S.-S.L.); (S.-H.L.); (J.L.); (K.-W.K.)
| | - Sang-Hoon Lee
- Animal Genetic Resource Research Center, National Institute of Animal Science, RDA, Hamyang 50000, Korea; (Y.-G.K.); (S.-S.L.); (S.-H.L.); (J.L.); (K.-W.K.)
| | - Jinwook Lee
- Animal Genetic Resource Research Center, National Institute of Animal Science, RDA, Hamyang 50000, Korea; (Y.-G.K.); (S.-S.L.); (S.-H.L.); (J.L.); (K.-W.K.)
| | - Kwan-Woo Kim
- Animal Genetic Resource Research Center, National Institute of Animal Science, RDA, Hamyang 50000, Korea; (Y.-G.K.); (S.-S.L.); (S.-H.L.); (J.L.); (K.-W.K.)
| | - Sung Woo Kim
- Animal Genetic Resource Research Center, National Institute of Animal Science, RDA, Hamyang 50000, Korea; (Y.-G.K.); (S.-S.L.); (S.-H.L.); (J.L.); (K.-W.K.)
- Correspondence: (S.W.K.); (B.K.); Tel.: +82-41-330-1246 (S.W.K. & B.K.); Fax: +82-41-330-1249 (S.W.K. & B.K.)
| | - Bongki Kim
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea; (Y.-D.J.); (Y.-J.P.)
- Correspondence: (S.W.K.); (B.K.); Tel.: +82-41-330-1246 (S.W.K. & B.K.); Fax: +82-41-330-1249 (S.W.K. & B.K.)
| |
Collapse
|
4
|
Park YJ, Kim JH, Kim HY, Park HB, Choe J, Kim GW, Baek SY, Chung HJ, Park YJ, Kim B. The expression and localization of V-ATPase and cytokeratin 5 during postnatal development of the pig epididymis. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2019; 33:1077-1086. [PMID: 32054197 PMCID: PMC7322665 DOI: 10.5713/ajas.19.0587] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 10/30/2019] [Indexed: 01/06/2023]
Abstract
Objective We examined the localization and expression of H+ pumping vacuolar ATPase (V-ATPase) and cytokeratin 5 (KRT5) in the epididymis of pigs, expressed in clear and basal cells, respectively, during postnatal development. Methods Epididymides were obtained from pigs at 1, 7, 21, 60, 120, and 180 days of age; we observed the localization and expression patterns of V-ATPase and KRT5 in the different regions of these organs, namely, the caput, corpus, and cauda. The differentiation of epididymal epithelial cells was determined by immunofluorescence labeling using cell-type-specific markers and observed using confocal microscopy. Results At postnatal day 5 (PND5), the localization of clear cells commenced migration from the cauda toward the caput. Although at PND120, goblet-shaped clear cells were detected along the entire length of the epididymis, those labeled for V-ATPase had disappeared from the corpus to cauda and were maintained only in the caput epididymis in adult pigs. In contrast, whereas basal cells labeled for KRT5 were only present in the vas deferens at birth, they were detected in all regions of the epididymis at PND60. These cells were localized at the base of the epithelium; however, no basal cells characterized by luminally extending cell projections were observed in any of the adult epididymides examined. Conclusion The differentiation of clear and basal cells progressively initiates in a retrograde manner from the cauda to the caput epididymis. The cell-type-specific distribution and localization of the epithelial cells play important roles in establishing a unique luminal environment for sperm maturation and storage in the pig epididymis.
Collapse
Affiliation(s)
- Yun-Jae Park
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| | - Ji-Hyuk Kim
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| | - Hack-Youn Kim
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| | - Hee-Bok Park
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| | - Juhui Choe
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| | - Gye-Woong Kim
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| | - Sun-Young Baek
- Division of Swine Science, National Institute of Animal Science, Rural Development Administration, Cheonan 31172, Korea
| | - Hak-Jae Chung
- Division of Swine Science, National Institute of Animal Science, Rural Development Administration, Cheonan 31172, Korea
| | - Yoo-Jin Park
- Department of Animal Science and Technology, Chung-Ang University, Anseong 17546, Korea
| | - Bongki Kim
- Department of Animal Resources Science, Kongju National University, Yesan 32439, Korea
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Park YJ, Battistone MA, Kim B, Breton S. Relative contribution of clear cells and principal cells to luminal pH in the mouse epididymis. Biol Reprod 2018; 96:366-375. [PMID: 28203710 DOI: 10.1095/biolreprod.116.144857] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/06/2016] [Accepted: 01/04/2017] [Indexed: 12/27/2022] Open
Abstract
While spermatozoa undergo epididymal maturation, they remain quiescent thanks to the establishment of a low luminal pH. This study is aimed at determining how epithelial cells lining the epididymal lumen work together to maintain and regulate this acidic milieu. In particular, we examined the relative contribution of clear cells (CCs) and principal cells (PCs) to this process. Functional analysis in the mouse cauda epididymidis (Cd) perfused in vivo showed that the pH of a control solution remained constant at pH 6.6 after perfusion through the Cd lumen. In contrast, the pH of both an acidic (pH 5.8) and alkaline (pH 7.8) perfusate was progressively restored toward the control acidic pH. Pharmacological studies indicated the contribution of cystic fibrosis transmembrane regulator, previously shown to be present in the apical membrane of PCs, to the recovery from an acidic pH of 5.8. In addition, we found that CCs and PCs equally contribute to the recovery from an alkaline of 7.8, via the H+ pumping vacuolar ATPase (V-ATPase) located in CCs, and the Na+/H+ exchanger type 3 (NHE3) located in PCs. Immunofluorescence labeling showed apical membrane accumulation of the V-ATPase in CCs at pH 7.8, and its internalization at pH 5.8 compared to pH 6.6. Immunofluorescence showed expression of NHE3, but absence of NHE2, in PCs located in the Cd. RT-PCR and western blotting showed expression of NHE3 in all epididymal regions. Luminal 8-(4-chlorophenylthio)adenosine 3΄,5΄-cyclic monophosphate (cpt-cAMP) partially inhibited luminal pH recovery from pH 7.8. However, cpt-cAMP induced an increase in V-ATPase apical membrane accumulation at this pH. Cell fractionation studies showed the apical accumulation of NHE3 from intracellular vesicles at pH 7.8 versus 6.6, and prevention of this effect by cpt-cAMP. These results indicate the participation of both CCs and PCs in the regulation of luminal pH in the epididymis. Our study also shows the dual role of PCs in HCO3− and H+ secretion, and that this switch from base to acid secretion depends on the luminal environment. Characterization of the respective roles of CCs and PCs in the regulation of the optimal luminal condition for epididymal sperm maturation should provide new frameworks for the evaluation and treatment of male infertility.
Collapse
Affiliation(s)
- Yoo-Jin Park
- Department of Laboratory Medicine,College of Medicine,The Catholic University of Korea,Seoul,Republic of Korea
| | - Maria Agustina Battistone
- Instituto de Biología y Medicina Experimental (IByME-CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Bongki Kim
- Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.,Division of Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Korea
| | - Sylvie Breton
- Lesieur, R&D Center ESPCI ParisTech - CNRS, Coudekerque-Branche, France
| |
Collapse
|
7
|
Pamarthy S, Kulshrestha A, Katara GK, Beaman KD. The curious case of vacuolar ATPase: regulation of signaling pathways. Mol Cancer 2018; 17:41. [PMID: 29448933 PMCID: PMC5815226 DOI: 10.1186/s12943-018-0811-3] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 02/07/2018] [Indexed: 02/06/2023] Open
Abstract
The Vacuolar ATPase (V-ATPase) is a proton pump responsible for controlling the intracellular and extracellular pH of cells. The structure of V-ATPase has been highly conserved among all eukaryotic cells and is involved in diverse functions across species. V-ATPase is best known for its acidification of endosomes and lysosomes and is also important for luminal acidification of specialized cells. Several reports have suggested the involvement of V-ATPase in maintaining an alkaline intracellular and acidic extracellular pH thereby aiding in proliferation and metastasis of cancer cells respectively. Increased expression of V-ATPase and relocation to the plasma membrane aids in cancer modulates key tumorigenic cell processes like autophagy, Warburg effect, immunomoduation, drug resistance and most importantly cancer cell signaling. In this review, we discuss the direct role of V-ATPase in acidification and indirect regulation of signaling pathways, particularly Notch Signaling.
Collapse
Affiliation(s)
- Sahithi Pamarthy
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, 60611, USA
| | - Arpita Kulshrestha
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA
| | - Gajendra K Katara
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA
| | - Kenneth D Beaman
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
| |
Collapse
|
8
|
Zhang J, Fuster DG, Cameron MA, Quiñones H, Griffith C, Xie XS, Moe OW. Incomplete distal renal tubular acidosis from a heterozygous mutation of the V-ATPase B1 subunit. Am J Physiol Renal Physiol 2014; 307:F1063-71. [PMID: 25164082 DOI: 10.1152/ajprenal.00408.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Congenital distal renal tubular acidosis (RTA) from mutations of the B1 subunit of V-ATPase is considered an autosomal recessive disease. We analyzed a distal RTA kindred with a truncation mutation of B1 (p.Phe468fsX487) previously shown to have failure of assembly into the V1 domain of V-ATPase. All heterozygous carriers in this kindred have normal plasma HCO3- concentrations and thus evaded the diagnosis of RTA. However, inappropriately high urine pH, hypocitraturia, and hypercalciuria were present either individually or in combination in the heterozygotes at baseline. Two of the heterozygotes studied also had inappropriate urinary acidification with acute ammonium chloride loading and an impaired urine-blood Pco2 gradient during bicarbonaturia, indicating the presence of a H+ gradient and flux defects. In normal human renal papillae, wild-type B1 is located primarily on the plasma membrane, but papilla from one of the heterozygote who had kidney stones but not nephrocalcinosis showed B1 in both the plasma membrane as well as diffuse intracellular staining. Titration of increasing amounts of the mutant B1 subunit did not exhibit negative dominance over the expression, cellular distribution, or H+ pump activity of wild-type B1 in mammalian human embryonic kidney-293 cells and in V-ATPase-deficient Saccharomyces cerevisiae. This is the first demonstration of renal acidification defects and nephrolithiasis in heterozygous carriers of a mutant B1 subunit that cannot be attributable to negative dominance. We propose that heterozygosity may lead to mild real acidification defects due to haploinsufficiency. B1 heterozygosity should be considered in patients with calcium nephrolithiasis and urinary abnormalities such as alkalinuria or hypocitraturia.
Collapse
Affiliation(s)
- Jianning Zhang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Daniel G Fuster
- Department of Nephrology and Hypertension and Institute of Biochemistry and Molecular Medicine, Inselspital, University of Bern, Bern, Switzerland
| | - Mary Ann Cameron
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Henry Quiñones
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Carolyn Griffith
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Xiao-Song Xie
- McDermott Center of Human Development, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Orson W Moe
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas;
| |
Collapse
|
9
|
Abstract
Specialized cells in the body express high levels of V-ATPase in their plasma membrane and respond to hormonal and nonhormonal cues to regulate extracellular acidification. Mutations in or loss of some V-ATPase subunits cause several disorders, including renal distal tubular acidosis and male infertility. This review focuses on the regulation of V-ATPase-dependent luminal acidification in renal intercalated cells and epididymal clear cells, which are key players in these physiological processes.
Collapse
Affiliation(s)
- Sylvie Breton
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, Massachusetts General Hospital, Boston, MA, USA
| | | |
Collapse
|
10
|
|
11
|
Johnson RM, Allen C, Melman SD, Waller A, Young SM, Sklar LA, Parra KJ. Identification of inhibitors of vacuolar proton-translocating ATPase pumps in yeast by high-throughput screening flow cytometry. Anal Biochem 2009; 398:203-11. [PMID: 20018164 DOI: 10.1016/j.ab.2009.12.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 09/22/2009] [Accepted: 12/10/2009] [Indexed: 11/28/2022]
Abstract
Fluorescence intensity of the pH-sensitive carboxyfluorescein derivative 2,7-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) was monitored by high-throughput flow cytometry in living yeast cells. We measured fluorescence intensity of BCECF trapped in yeast vacuoles, acidic compartments equivalent to lysosomes where vacuolar proton-translocating ATPases (V-ATPases) are abundant. Because V-ATPases maintain a low pH in the vacuolar lumen, V-ATPase inhibition by concanamycin A alkalinized the vacuole and increased BCECF fluorescence. Likewise, V-ATPase-deficient mutant cells had greater fluorescence intensity than wild-type cells. Thus, we detected an increase of fluorescence intensity after short- and long-term inhibition of V-ATPase function. We used yeast cells loaded with BCECF to screen a small chemical library of structurally diverse compounds to identify V-ATPase inhibitors. One compound, disulfiram, enhanced BCECF fluorescence intensity (although to a degree beyond that anticipated for pH changes alone in the mutant cells). Once confirmed by dose-response assays (EC(50)=26 microM), we verified V-ATPase inhibition by disulfiram in secondary assays that measured ATP hydrolysis in vacuolar membranes. The inhibitory action of disulfiram against V-ATPase pumps revealed a novel effect previously unknown for this compound. Because V-ATPases are highly conserved, new inhibitors identified could be used as research and therapeutic tools in cancer, viral infections, and other diseases where V-ATPases are involved.
Collapse
Affiliation(s)
- Rebecca M Johnson
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | | | | | | | | | | | | |
Collapse
|
12
|
Ediger B, Melman SD, Pappas DL, Finch M, Applen J, Parra KJ. The tether connecting cytosolic (N terminus) and membrane (C terminus) domains of yeast V-ATPase subunit a (Vph1) is required for assembly of V0 subunit d. J Biol Chem 2009; 284:19522-32. [PMID: 19473972 DOI: 10.1074/jbc.m109.013375] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
V-ATPases are molecular motors that reversibly disassemble in vivo. Anchored in the membrane is subunit a. Subunit a has a movable N terminus that switches positions during disassembly and reassembly. Deletions were made at residues securing the N terminus of subunit a (yeast isoform Vph1) to its membrane-bound C-terminal domain in order to understand the role of this conserved region for V-ATPase function. Shrinking of the tether made cells pH-sensitive (vma phenotype) because assembly of V(0) subunit d was harmed. Subunit d did not co-immunoprecipitate with subunit a and the c-ring. Cells contained pools of V(1) and V(0)(-d) that failed to form V(1)V(0), and very low levels of V-ATPase subunits were found at the membrane. Although subunit d expression was stable and at wild-type levels, growth defects were rescued by exogenous VMA6 (subunit d). Stable V(1)V(0) assembled after yeast cells were co-transformed with VMA6 and mutant VPH1. Tether-less V(1)V(0) was delivered to the vacuole and active. It retained 63-71% of the wild-type activity and was responsive to glucose. Tether-less V(1)V(0) disassembled and reassembled after brief glucose depletion and readdition. The N terminus retained binding to V(1) subunits and the C terminus to phosphofructokinase. Thus, no major structural change was generated at the N and C termini of subunit a. We concluded that early steps of V(0) assembly and trafficking were likely impaired by shorter tethers and rescued by VMA6.
Collapse
Affiliation(s)
- Benjamin Ediger
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA
| | | | | | | | | | | |
Collapse
|
13
|
Holliday LS, Ostrov DA, Wronski TJ, Dolce C. Osteoclast polarization and orthodontic tooth movement. Orthod Craniofac Res 2009; 12:105-12. [DOI: 10.1111/j.1601-6343.2009.01443.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
14
|
The yeast lysosome-like vacuole: endpoint and crossroads. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:650-63. [PMID: 18786576 DOI: 10.1016/j.bbamcr.2008.08.003] [Citation(s) in RCA: 292] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 08/01/2008] [Accepted: 08/06/2008] [Indexed: 12/21/2022]
Abstract
Fungal vacuoles are acidic organelles with degradative and storage capabilities that have many similarities to mammalian lysosomes and plant vacuoles. In the past several years, well-developed genetic, genomic, biochemical and cell biological tools in S. cerevisiae have provided fresh insights into vacuolar protein sorting, organelle acidification, ion homeostasis, autophagy, and stress-related functions of the vacuole, and these insights have often found parallels in mammalian lysosomes. This review provides a broad overview of the defining features and functions of S. cerevisiae vacuoles and compares these features to mammalian lysosomes. Recent research challenges the traditional view of vacuoles and lysosomes as simply the terminal compartment of biosynthetic and endocytic pathways (i.e. the "garbage dump" of the cell), and suggests instead that these compartments are unexpectedly dynamic and highly regulated.
Collapse
|
15
|
Blake-Palmer KG, Su Y, Smith AN, Karet FE. Molecular cloning and characterization of a novel form of the human vacuolar H+-ATPase e-subunit: An essential proton pump component. Gene 2007; 393:94-100. [PMID: 17350184 DOI: 10.1016/j.gene.2007.01.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 01/25/2007] [Accepted: 01/26/2007] [Indexed: 11/17/2022]
Abstract
Several of the 13 subunits comprising mammalian H(+)-ATPases have multiple alternative forms, encoded by separate genes and with differing tissue expression patterns. These may play an important role in the intracellular localization and activity of H(+)-ATPases. Here we report the cloning of a previously uncharacterized human gene, ATP6V0E2, encoding a novel H(+)-ATPase e-subunit designated e2. We demonstrate that in contrast to the ubiquitously expressed gene encoding the e1 subunit (previously called e), this novel gene is expressed in a more restricted tissue distribution, particularly kidney and brain. We show by complementation studies in a yeast strain deficient for the ortholog of this subunit, that either form of the e-subunit is essential for proper proton pump function. The identification of this novel form of the e-subunit lends further support to the hypothesis that subunit differences may play a key role in the structure, site and function of H(+)-ATPases within the cell.
Collapse
Affiliation(s)
- Katherine G Blake-Palmer
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, UK
| | | | | | | |
Collapse
|
16
|
Wisløff H, Gharehnia B, Flåøyen A, Andersen KJ. Effects of 3-methoxy-2(5H)-furanone-containing extracts from Narthecium ossifragum (L.) Huds. on renal tubular cells in vitro. Toxicon 2007; 49:368-77. [PMID: 17141820 DOI: 10.1016/j.toxicon.2006.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Revised: 10/18/2006] [Accepted: 10/23/2006] [Indexed: 11/19/2022]
Abstract
Narthecium ossifragum, a perennial herb of the lily family, causes toxic renal tubular necrosis in several ruminant species. 3-Methoxy-2(5H)-furanone (3M2F) has been identified as a nephrotoxin present in N. ossifragum extracts. We studied effects of three different 3M2F-containing fractions isolated from N. ossifragum and synthetic 3M2F on the porcine kidney cell line LLC-PK1. In some of the experiments, we included the glioma cell lines U251 and BT4Cn to compare the effects of the toxin on LLC-PK1 cells to the effect on these cell lines. The synthetic 3M2F was shown to be only mildly toxic, and the most purified fraction from N. ossifragum showed the highest degree of toxicity in our studies. When monolayer cultures were exposed to increasing amounts of 3M2F-containing extract, a dose-dependent increase in cell death was observed. Similarly, reduced neutral red uptake and 3H-thymidine uptake (DNA synthesis) was observed. There was increased apoptotic activity in the LLC-PK1 cells with increasing concentration of 3M2F-containing extract. Multicellular three-dimensional spheroids from LLC-PK1 cells stopped fluid transport, showed degenerative changes and collapsed totally 6 h after extract exposure. Our findings indicate junctional damage, reduced cellular endocytosis and DNA-synthesis as well as induction of apoptosis as possible mechanisms for the acute tubular necrosis observed in ruminant species.
Collapse
Affiliation(s)
- Helene Wisløff
- Department of Pathology, National Veterinary Institute, P.O. Box 8156 Dep, 0033 Oslo, Norway.
| | | | | | | |
Collapse
|