1
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Hodeify R, Kreydiyyeh S, Zaid LMJ. Identified and potential internalization signals involved in trafficking and regulation of Na +/K + ATPase activity. Mol Cell Biochem 2024; 479:1583-1598. [PMID: 37634170 PMCID: PMC11254989 DOI: 10.1007/s11010-023-04831-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/14/2023] [Indexed: 08/29/2023]
Abstract
The sodium-potassium pump (NKA) or Na+/K+ ATPase consumes around 30-40% of the total energy expenditure of the animal cell on the generation of the sodium and potassium electrochemical gradients that regulate various electrolyte and nutrient transport processes. The vital role of this protein entails proper spatial and temporal regulation of its activity through modulatory mechanisms involving its expression, localization, enzymatic activity, and protein-protein interactions. The residence of the NKA at the plasma membrane is compulsory for its action as an antiporter. Despite the huge body of literature reporting on its trafficking between the cell membrane and intracellular compartments, the mechanisms controlling the trafficking process are by far the least understood. Among the molecular determinants of the plasma membrane proteins trafficking are intrinsic sequence-based endocytic motifs. In this review, we (i) summarize previous reports linking the regulation of Na+/K+ ATPase trafficking and/or plasma membrane residence to its activity, with particular emphasis on the endocytic signals in the Na+/K+ ATPase alpha-subunit, (ii) map additional potential internalization signals within Na+/K+ ATPase catalytic alpha-subunit, based on canonical and noncanonical endocytic motifs reported in the literature, (iii) pinpoint known and potential phosphorylation sites associated with NKA trafficking, (iv) highlight our recent studies on Na+/K+ ATPase trafficking and PGE2-mediated Na+/K+ ATPase modulation in intestine, liver, and kidney cells.
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Affiliation(s)
- Rawad Hodeify
- Department of Biotechnology, School of Arts and Sciences, American University of Ras Al Khaimah, Ras Al Khaimah, United Arab Emirates.
| | - Sawsan Kreydiyyeh
- Department of Biology, Faculty of Arts & Sciences, American University of Beirut, Beirut, Lebanon
| | - Leen Mohammad Jamal Zaid
- Department of Biotechnology, School of Arts and Sciences, American University of Ras Al Khaimah, Ras Al Khaimah, United Arab Emirates
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2
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Kryvenko V, Vadász I. Alveolar-capillary endocytosis and trafficking in acute lung injury and acute respiratory distress syndrome. Front Immunol 2024; 15:1360370. [PMID: 38533500 PMCID: PMC10963603 DOI: 10.3389/fimmu.2024.1360370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/29/2024] [Indexed: 03/28/2024] Open
Abstract
Acute respiratory distress syndrome (ARDS) is associated with high morbidity and mortality but lacks specific therapeutic options. Diverse endocytic processes play a key role in all phases of acute lung injury (ALI), including the initial insult, development of respiratory failure due to alveolar flooding, as a consequence of altered alveolar-capillary barrier function, as well as in the resolution or deleterious remodeling after injury. In particular, clathrin-, caveolae-, endophilin- and glycosylphosphatidyl inositol-anchored protein-mediated endocytosis, as well as, macropinocytosis and phagocytosis have been implicated in the setting of acute lung damage. This manuscript reviews our current understanding of these endocytic pathways and subsequent intracellular trafficking in various phases of ALI, and also aims to identify potential therapeutic targets for patients with ARDS.
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Affiliation(s)
- Vitalii Kryvenko
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
| | - István Vadász
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
- The Cardio-Pulmonary Institute (CPI), Giessen, Germany
- Institute for Lung Health (ILH), Giessen, Germany
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3
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Banerjee M, Li Z, Gao Y, Lai F, Huang M, Zhang Z, Cai L, Sanabria J, Gao T, Xie Z, Pierre SV. Inverse agonism at the Na/K-ATPase receptor reverses EMT in prostate cancer cells. Prostate 2021; 81:667-682. [PMID: 33956349 PMCID: PMC10071553 DOI: 10.1002/pros.24144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/22/2020] [Accepted: 02/19/2021] [Indexed: 12/14/2022]
Abstract
The surface expression of Na/K-ATPase α1 (NKA) is significantly reduced in primary prostate tumors and further decreased in bone metastatic lesions. Here, we show that the loss of cell surface expression of NKA induces epithelial-mesenchymal transition (EMT) and promotes metastatic potential and tumor growth of prostate cancer (PCa) by decreasing the expression of E-cadherin and increasing c-Myc expression via the activation of Src/FAK pathways. Mechanistically, reduced surface expression of NKA in PCa is due to increased endocytosis through the activation of NKA/Src receptor complex. Using a high-throughput NKA ligand-screening platform, we have discovered MB5 as an inverse agonist of the NKA/Src receptor complex, capable of blocking the endocytosis of NKA. MB5 treatment increased NKA expression and E-cadherin in PCa cells, which reversed EMT and consequently decreased the invasion and growth of spheroid models and tumor xenografts. Thus, we have identified a hitherto unrecognized mechanism that regulates EMT and invasiveness of PCa and demonstrated for the first time the feasibility of identifying inverse agonists of receptor NKA/Src complex and their potential utility as anticancer drugs. We, therefore, conclude that cell surface expression of α1 NKA can be targeted for the development of new therapeutics against aggressive PCa and that MB5 may serve as a prototype for drug development against EMT in metastatic PCa.
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Affiliation(s)
- Moumita Banerjee
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
| | - Zhichuan Li
- Department of Physiology, Pharmacology, and Medicine, University of Toledo Health Science Campus, Toledo, Ohio, USA
| | - Yingnyu Gao
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
- Institute of Edible Fungi, Shanghai Academy of Agriculture Science, Shanghai, China
| | - Fangfang Lai
- Department of Physiology, Pharmacology, and Medicine, University of Toledo Health Science Campus, Toledo, Ohio, USA
- Institute of Materia Medica, Peking Union Medical College, Beijing, China
| | - Minqi Huang
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
| | - Zhongbing Zhang
- Department of Physiology, Pharmacology, and Medicine, University of Toledo Health Science Campus, Toledo, Ohio, USA
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Liquan Cai
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
| | - Juan Sanabria
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
- Department of Surgery, Joan Edwards School of Medicine Marshall University, Huntington, West Virginia, USA
| | - Tianyan Gao
- Department of Molecular and Cellular Biochemistry, Markey Cancer Research Center, University of Kentucky, Lexington, Kentucky, USA
| | - Zijian Xie
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
| | - Sandrine V Pierre
- Marshall Institute for Interdisciplinary Research (MIIR), Marshall University, Huntington, West Virginia, USA
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López-Hernández T, Haucke V, Maritzen T. Endocytosis in the adaptation to cellular stress. Cell Stress 2020; 4:230-247. [PMID: 33024932 PMCID: PMC7520666 DOI: 10.15698/cst2020.10.232] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/24/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022] Open
Abstract
Cellular life is challenged by a multitude of stress conditions, triggered for example by alterations in osmolarity, oxygen or nutrient supply. Hence, cells have developed sophisticated stress responses to cope with these challenges. Some of these stress programs such as the heat shock response are understood in great detail, while other aspects remain largely elusive including potential stress-dependent adaptations of the plasma membrane proteome. The plasma membrane is not only the first point of encounter for many types of environmental stress, but given the diversity of receptor proteins and their associated molecules also represents the site at which many cellular signal cascades originate. Since these signaling pathways affect virtually all aspects of cellular life, changes in the plasma membrane proteome appear ideally suited to contribute to the cellular adaptation to stress. The most rapid means to alter the cell surface proteome in response to stress is by alterations in endocytosis. Changes in the overall endocytic flux or in the endocytic regulation of select proteins conceivably can help to counteract adverse environmental conditions. In this review we summarize recent data regarding stress-induced changes in endocytosis and discuss how these changes might contribute to the cellular adaptation to stress in different systems. Future studies will be needed to uncover the underlying mechanisms in detail and to arrive at a coherent picture.
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Affiliation(s)
- Tania López-Hernández
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
- Freie Universität Berlin, Faculty of Biology, Chemistry, Pharmacy, 14195 Berlin, Germany
| | - Tanja Maritzen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
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5
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Ju M, Ioannidou S, Munro P, Rämö O, Vihinen H, Jokitalo E, Shima DT. A Na,K-ATPase-Fodrin-Actin Membrane Cytoskeleton Complex is Required for Endothelial Fenestra Biogenesis. Cells 2020; 9:cells9061387. [PMID: 32503129 PMCID: PMC7349347 DOI: 10.3390/cells9061387] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 05/30/2020] [Accepted: 05/30/2020] [Indexed: 01/07/2023] Open
Abstract
Fenestrae are transcellular plasma membrane pores that mediate blood–tissue exchange in specialised vascular endothelia. The composition and biogenesis of the fenestra remain enigmatic. We isolated and characterised the protein composition of large patches of fenestrated plasma membrane, termed sieve plates. Loss-of-function experiments demonstrated that two components of the sieve plate, moesin and annexin II, were positive and negative regulators of fenestra formation, respectively. Biochemical analyses showed that moesin is involved in the formation of an actin–fodrin submembrane cytoskeleton that was essential for fenestra formation. The link between the fodrin cytoskeleton and the plasma membrane involved the fenestral pore protein PV-1 and Na,K-ATPase, which is a key regulator of signalling during fenestra formation both in vitro and in vivo. These findings provide a conceptual framework for fenestra biogenesis, linking the dynamic changes in plasma membrane remodelling to the formation of a submembrane cytoskeletal signalling complex.
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Affiliation(s)
- Meihua Ju
- Translational Vision Research, UCL Institute of Ophthalmology, London EC1v 9EL, UK;
| | | | - Peter Munro
- Electron Microscopy Unit, UCL Institute of Ophthalmology, London EC1v 9EL, UK;
| | - Olli Rämö
- Cell and Molecular Biology Program, University of Helsinki, 00014 Helsinki, Finland; (O.R.); (E.J.)
| | - Helena Vihinen
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland;
| | - Eija Jokitalo
- Cell and Molecular Biology Program, University of Helsinki, 00014 Helsinki, Finland; (O.R.); (E.J.)
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland;
| | - David T. Shima
- Translational Vision Research, UCL Institute of Ophthalmology, London EC1v 9EL, UK;
- Correspondence: ; Tel.: +44-(0)7-932-042-570
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6
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Marcus EA, Tokhtaeva E, Jimenez JL, Wen Y, Naini BV, Heard AN, Kim S, Capri J, Cohn W, Whitelegge JP, Vagin O. Helicobacter pylori infection impairs chaperone-assisted maturation of Na-K-ATPase in gastric epithelium. Am J Physiol Gastrointest Liver Physiol 2020; 318:G931-G945. [PMID: 32174134 PMCID: PMC7272721 DOI: 10.1152/ajpgi.00266.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 01/31/2023]
Abstract
Helicobacter pylori infection always induces gastritis, which may progress to ulcer disease or cancer. The mechanisms underlying mucosal injury by the bacteria are incompletely understood. Here, we identify a novel pathway for H. pylori-induced gastric injury, the impairment of maturation of the essential transport enzyme and cell adhesion molecule, Na-K-ATPase. Na-K-ATPase comprises α- and β-subunits that assemble in the endoplasmic reticulum (ER) before trafficking to the plasma membrane. Attachment of H. pylori to gastric epithelial cells increased Na-K-ATPase ubiquitylation, decreased its surface and total levels, and impaired ion balance. H. pylori did not alter degradation of plasmalemma-resident Na-K-ATPase subunits or their mRNA levels. Infection decreased association of α- and β-subunits with ER chaperone BiP and impaired assembly of α/β-heterodimers, as was revealed by quantitative mass spectrometry and immunoblotting of immunoprecipitated complexes. The total level of BiP was not altered, and the decrease in interaction with BiP was not observed for other BiP client proteins. The H. pylori-induced decrease in Na-K-ATPase was prevented by BiP overexpression, stopping protein synthesis, or inhibiting proteasomal, but not lysosomal, protein degradation. The results indicate that H. pylori impairs chaperone-assisted maturation of newly made Na-K-ATPase subunits in the ER independently of a generalized ER stress and induces their ubiquitylation and proteasomal degradation. The decrease in Na-K-ATPase levels is also seen in vivo in the stomachs of gerbils and chronically infected children. Further understanding of H. pylori-induced Na-K-ATPase degradation will provide insights for protection against advanced disease.NEW & NOTEWORTHY This work provides evidence that Helicobacter pylori decreases levels of Na-K-ATPase, a vital transport enzyme, in gastric epithelia, both in acutely infected cultured cells and in chronically infected patients and animals. The bacteria interfere with BiP-assisted folding of newly-made Na-K-ATPase subunits in the endoplasmic reticulum, accelerating their ubiquitylation and proteasomal degradation and decreasing efficiency of the assembly of native enzyme. Decreased Na-K-ATPase expression contributes to H. pylori-induced gastric injury.
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Affiliation(s)
- Elizabeth A Marcus
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
| | - Elmira Tokhtaeva
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
| | - Jossue L Jimenez
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
| | - Yi Wen
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
| | - Bita V Naini
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ashley N Heard
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
| | - Samuel Kim
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
| | - Joseph Capri
- Pasarow Mass Spectrometry Laboratory, The Neuropsychiatric Insititute-Semel Institute, University of California, Los Angeles, California
| | - Whitaker Cohn
- Pasarow Mass Spectrometry Laboratory, The Neuropsychiatric Insititute-Semel Institute, University of California, Los Angeles, California
| | - Julian P Whitelegge
- Pasarow Mass Spectrometry Laboratory, The Neuropsychiatric Insititute-Semel Institute, University of California, Los Angeles, California
| | - Olga Vagin
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California
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7
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Wang X, Liu J, Drummond CA, Shapiro JI. Sodium potassium adenosine triphosphatase (Na/K-ATPase) as a therapeutic target for uremic cardiomyopathy. Expert Opin Ther Targets 2017; 21:531-541. [PMID: 28338377 PMCID: PMC5590225 DOI: 10.1080/14728222.2017.1311864] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 03/23/2017] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Clinically, patients with significant reductions in renal function present with cardiovascular dysfunction typically termed, uremic cardiomyopathy. It is a progressive series of cardiac pathophysiological changes, including left ventricular diastolic dysfunction and hypertrophy (LVH) which sometimes progress to left ventricular dilation (LVD) and systolic dysfunction in the setting of chronic kidney disease (CKD). Uremic cardiomyopathy is almost ubiquitous in patients afflicted with end stage renal disease (ESRD). Areas covered: This article reviews recent epidemiology, pathophysiology of uremic cardiomyopathy and provide a board overview of Na/K-ATPase research with detailed discussion on the mechanisms of Na/K-ATPase/Src/ROS amplification loop. We also present clinical and preclinical evidences as well as molecular mechanism of this amplification loop in the development of uremic cardiomyopathy. A potential therapeutic peptide that targets on this loop is discussed. Expert opinion: Current clinical treatment for uremic cardiomyopathy remains disappointing. Targeting the ROS amplification loop mediated by the Na/K-ATPase signaling function may provide a novel therapeutic target for uremic cardiomyopathy and related diseases. Additional studies of Na/K-ATPase and other strategies that regulate this loop will lead to new therapeutics.
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Affiliation(s)
- Xiaoliang Wang
- a Joan C Edwards School of Medicine at Marshall University , Huntington , WV , United States
- b University of Toledo College of Medicine and Life Sciences , Toledo , OH , United States
| | - Jiang Liu
- a Joan C Edwards School of Medicine at Marshall University , Huntington , WV , United States
| | - Christopher A Drummond
- b University of Toledo College of Medicine and Life Sciences , Toledo , OH , United States
| | - Joseph I Shapiro
- a Joan C Edwards School of Medicine at Marshall University , Huntington , WV , United States
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Banday AA. Chronic insulin treatment phosphorylates the renal Na-K-ATPase α1-subunit at serine 16/23 and reduces its activity involving PI3-kinase-dependent PKC activation. Am J Physiol Renal Physiol 2016; 311:F958-F966. [PMID: 27605582 DOI: 10.1152/ajprenal.00355.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 08/31/2016] [Indexed: 11/22/2022] Open
Abstract
The regulation of Na-K-ATPase in various tissues is under the control of a number of hormones and peptides that exert both short- and long-term control over its activity. The present study was performed to investigate the effect of chronic insulin treatment on Na-K-ATPase in renal proximal tubular cells. Incubation of opossum kidney (OK) cells, transfected with the rat Na-K-ATPase α1-subunit, with 1 nmol/l insulin for 48 h decreased Na-K-ATPase activity. Insulin decreased α1-protein content and increased α1-serine phosphorylation and α1-adaptor protein 2 (AP2) interaction. Removal of the 26 NH2-terminal (-NT) amino acid from the α1-subunit containing serine/threonine sites abolished the insulin-mediated serine phosphorylation and inhibition of Na-K-ATPase. Substitution of serine 16 and 23 with alanine showed a comparable effect on -NT. Insulin increased the activity of protein kinase C (PKC), which was blocked by the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin. Both PI3K and PKC inhibitors abolished the insulin-mediated inhibition of Na-K-ATPase. Insulin increased the expression of PKC-β1, -δ, -ξ, and-λ; however, only PKC-ξ/λ-specific inhibitors blocked insulin-induced phosphorylation and inhibition of Na-K-ATPase. Our data demonstrate that insulin activates the atypical PKC isoforms-ξ/λ via the PI3K pathway. PKC-ξ/λ-induced phosphorylation of the α1-subunit at serine 16 and 23 leads to AP2 recruitment, degradation, and a decrease in Na-K-ATPase activity.
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Tokhtaeva E, Capri J, Marcus EA, Whitelegge JP, Khuzakhmetova V, Bukharaeva E, Deiss-Yehiely N, Dada LA, Sachs G, Fernandez-Salas E, Vagin O. Septin dynamics are essential for exocytosis. J Biol Chem 2015; 290:5280-97. [PMID: 25575596 DOI: 10.1074/jbc.m114.616201] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Septins are a family of 14 cytoskeletal proteins that dynamically form hetero-oligomers and organize membrane microdomains for protein complexes. The previously reported interactions with SNARE proteins suggested the involvement of septins in exocytosis. However, the contradictory results of up- or down-regulation of septin-5 in various cells and mouse models or septin-4 in mice suggested either an inhibitory or a stimulatory role for these septins in exocytosis. The involvement of the ubiquitously expressed septin-2 or general septin polymerization in exocytosis has not been explored to date. Here, by nano-LC with tandem MS and immunoblot analyses of the septin-2 interactome in mouse brain, we identified not only SNARE proteins but also Munc-18-1 (stabilizes assembled SNARE complexes), N-ethylmaleimide-sensitive factor (NSF) (disassembles SNARE complexes after each membrane fusion event), and the chaperones Hsc70 and synucleins (maintain functional conformation of SNARE proteins after complex disassembly). Importantly, α-soluble NSF attachment protein (SNAP), the adaptor protein that mediates NSF binding to the SNARE complex, did not interact with septin-2, indicating that septins undergo reorganization during each exocytosis cycle. Partial depletion of septin-2 by siRNA or impairment of septin dynamics by forchlorfenuron inhibited constitutive and stimulated exocytosis of secreted and transmembrane proteins in various cell types. Forchlorfenuron impaired the interaction between SNAP-25 and its chaperone Hsc70, decreasing SNAP-25 levels in cultured neuroendocrine cells, and inhibited both spontaneous and stimulated acetylcholine secretion in mouse motor neurons. The results demonstrate a stimulatory role of septin-2 and the dynamic reorganization of septin oligomers in exocytosis.
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Affiliation(s)
- Elmira Tokhtaeva
- From the Departments of Physiology and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073
| | - Joe Capri
- The Neuropsychiatric Institute-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California 90024
| | - Elizabeth A Marcus
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073, Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California 90095
| | - Julian P Whitelegge
- The Neuropsychiatric Institute-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California 90024
| | - Venera Khuzakhmetova
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences, Kazan 420111, Russia, Kazan Federal University, Kazan 420008, Russia
| | - Ellya Bukharaeva
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences, Kazan 420111, Russia, Kazan Federal University, Kazan 420008, Russia
| | - Nimrod Deiss-Yehiely
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and
| | - Laura A Dada
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and
| | - George Sachs
- From the Departments of Physiology and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073
| | - Ester Fernandez-Salas
- Department of Pathology, School of Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Olga Vagin
- From the Departments of Physiology and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073,
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10
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Booth AEG, Tarafder AK, Hume AN, Recchi C, Seabra MC. A role for Na+,K+-ATPase α1 in regulating Rab27a localisation on melanosomes. PLoS One 2014; 9:e102851. [PMID: 25051489 PMCID: PMC4106853 DOI: 10.1371/journal.pone.0102851] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/23/2014] [Indexed: 12/23/2022] Open
Abstract
The mechanism(s) by which Rab GTPases are specifically recruited to distinct intracellular membranes remains elusive. Here we used Rab27a localisation onto melanosomes as a model to investigate Rab targeting. We identified the α1 subunit of Na+,K+-ATPase (ATP1a1) as a novel Rab27a interacting protein in melanocytes and showed that this interaction is direct with the intracellular M4M5 loop of ATP1a1 and independent of nucleotide bound status of the Rab. Knockdown studies in melanocytes revealed that ATP1a1 plays an essential role in Rab27a-dependent melanosome transport. Specifically, expression of ATP1a1, like the Rab27a GDP/GTP exchange factor (Rab3GEP), is essential for targeting and activation of Rab27a to melanosomes. Finally, we showed that the ability of Rab27a mutants to target to melanosomes correlates with the efficiency of their interaction with ATP1a1. Altogether these studies point to a new role for ATP1a1 as a regulator of Rab27a targeting and activation.
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Affiliation(s)
- Antonia E. G. Booth
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
| | - Abul K. Tarafder
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
| | - Alistair N. Hume
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
- School of Biomedical Sciences, University of Nottingham, Medical School, Queens Medical Centre, Nottingham, United Kingdom
| | - Chiara Recchi
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
| | - Miguel C. Seabra
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
- CEDOC, Faculdade de Ciencias Medicas, FCM, Universidade Nova de Lisboa, Lisboa, Portugal
- * E-mail:
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11
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Antonescu CN, McGraw TE, Klip A. Reciprocal regulation of endocytosis and metabolism. Cold Spring Harb Perspect Biol 2014; 6:a016964. [PMID: 24984778 DOI: 10.1101/cshperspect.a016964] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cellular uptake of many nutrients and micronutrients governs both their cellular availability and their systemic homeostasis. The cellular rate of nutrient or ion uptake (e.g., glucose, Fe(3+), K(+)) or efflux (e.g., Na(+)) is governed by a complement of membrane transporters and receptors that show dynamic localization at both the plasma membrane and defined intracellular membrane compartments. Regulation of the rate and mechanism of endocytosis controls the amounts of these proteins on the cell surface, which in many cases determines nutrient uptake or secretion. Moreover, the metabolic action of diverse hormones is initiated upon binding to surface receptors that then undergo regulated endocytosis and show distinct signaling patterns once internalized. Here, we examine how the endocytosis of nutrient transporters and carriers as well as signaling receptors governs cellular metabolism and thereby systemic (whole-body) metabolite homeostasis.
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Affiliation(s)
- Costin N Antonescu
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
| | - Timothy E McGraw
- Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10065
| | - Amira Klip
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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12
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Zhang LN, Li JX, Hao L, Sun YJ, Xie YH, Wu SM, Liu L, Chen XL, Gao ZB. Crosstalk between dopamine receptors and the Na⁺/K⁺-ATPase (review). Mol Med Rep 2013; 8:1291-9. [PMID: 24065247 DOI: 10.3892/mmr.2013.1697] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 09/05/2013] [Indexed: 11/06/2022] Open
Abstract
Dopamine (DA) receptors, which belong to the G protein-coupled receptor family, are the target of ~50% of all modern medicinal drugs and constitute a large and diverse class of proteins whose primary function is to transduce extracellular stimuli into intracellular signals. Na+/K+-ATPase (NKA) is ubiquitous and crucial for the maintenance of intracellular ion homeostasis and excitability. Furthermore, it plays a critical role in diverse effects, including clinical cardiotonic and cardioprotective effects, ischemic preconditioning in the brain, natriuresis, lung edema clearance and other processes. NKA regulation is of physiological and pharmacological importance and has species- and tissue-specific variations. The activation of DA receptors regulates NKA expression/activity and trafficking in various tissues and cells, for example in the kidney, lung, intestine, brain, non-pigmented ciliary epithelium and the vascular bed. DA receptor-mediated regulation of NKA mediates a diverse range of cellular responses and includes endocytosis/exocytosis, phosphorylation/dephosphorylation of the α subunit of NKA and multiple signaling pathways, including phosphatidylinositol (PI)-phospholipase C/protein kinase (PK) C, cAMP/PKA, PI3K, adaptor protein 2, tyrosine phosphatase and mitogen-activated protein kinase/extracellular signal-regulated protein kinase. Furthermore, in brain and HEK293T cells, D1 and D2 receptors exist in a complex with NKA. Among D1 and D2 receptors and NKA, regulations are reciprocal, which leads to crosstalk between DA receptors and NKA. In the present study, the current understanding of signaling mechanisms responsible for the crosstalk between DA receptors and NKA, as well as with specific consequent functions, is reviewed.
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Affiliation(s)
- Li-Nan Zhang
- Department of Pharmacy, College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, P.R. China
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13
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Benziane B, Björnholm M, Pirkmajer S, Austin RL, Kotova O, Viollet B, Zierath JR, Chibalin AV. Activation of AMP-activated protein kinase stimulates Na+,K+-ATPase activity in skeletal muscle cells. J Biol Chem 2012; 287:23451-63. [PMID: 22610379 DOI: 10.1074/jbc.m111.331926] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Contraction stimulates Na(+),K(+)-ATPase and AMP-activated protein kinase (AMPK) activity in skeletal muscle. Whether AMPK activation affects Na(+),K(+)-ATPase activity in skeletal muscle remains to be determined. Short term stimulation of rat L6 myotubes with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), activates AMPK and promotes translocation of the Na(+),K(+)-ATPase α(1)-subunit to the plasma membrane and increases Na(+),K(+)-ATPase activity as assessed by ouabain-sensitive (86)Rb(+) uptake. Cyanide-induced artificial anoxia, as well as a direct AMPK activator (A-769662) also increase AMPK phosphorylation and Na(+),K(+)-ATPase activity. Thus, different stimuli that target AMPK concomitantly increase Na(+),K(+)-ATPase activity. The effect of AICAR on Na(+),K(+)-ATPase in L6 myotubes was attenuated by Compound C, an AMPK inhibitor, as well as siRNA-mediated AMPK silencing. The effects of AICAR on Na(+),K(+)-ATPase were completely abolished in cultured primary mouse muscle cells lacking AMPK α-subunits. AMPK stimulation leads to Na(+),K(+)-ATPase α(1)-subunit dephosphorylation at Ser(18), which may prevent endocytosis of the sodium pump. AICAR stimulation leads to methylation and dephosphorylation of the catalytic subunit of the protein phosphatase (PP) 2A in L6 myotubes. Moreover, AICAR-triggered dephosphorylation of the Na(+),K(+)-ATPase was prevented in L6 myotubes deficient in PP2A-specific protein phosphatase methylesterase-1 (PME-1), indicating a role for the PP2A·PME-1 complex in AMPK-mediated regulation of Na(+),K(+)-ATPase. Thus contrary to the common paradigm, we report AMPK-dependent activation of an energy-consuming ion pumping process. This activation may be a potential mechanism by which exercise and metabolic stress activate the sodium pump in skeletal muscle.
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Affiliation(s)
- Boubacar Benziane
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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14
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Hayashi H, Naoi S, Nakagawa T, Nishikawa T, Fukuda H, Imajoh-Ohmi S, Kondo A, Kubo K, Yabuki T, Hattori A, Hirouchi M, Sugiyama Y. Sorting nexin 27 interacts with multidrug resistance-associated protein 4 (MRP4) and mediates internalization of MRP4. J Biol Chem 2012; 287:15054-65. [PMID: 22411990 DOI: 10.1074/jbc.m111.337931] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Multidrug resistance-associated protein 4 (MRP4/ABCC4) makes a vital contribution to the bodily distribution of drugs and endogenous compounds because of its cellular efflux abilities. However, little is known about the mechanism regulating its cell surface expression. MRP4 has a PDZ-binding motif, which is a potential sequence that modulates the membrane expression of MRP4 via interaction with PDZ adaptor proteins. To investigate this possible relationship, we performed GST pull-down assays and subsequent analysis with matrix-assisted laser desorption/ionization-time of flight mass spectrometry. This method identified sorting nexin 27 (SNX27) as the interacting PDZ adaptor protein with a PDZ-binding motif of MRP4. Its interaction was confirmed by a coimmunoprecipitation study using HEK293 cells. Knockdown of SNX27 by siRNA in HEK293 cells raised MRP4 expression on the plasma membrane, increased the extrusion of 6-[(14)C]mercaptopurine, an MRP4 substrate, and conferred resistance against 6-[(14)C]mercaptopurine. Cell surface biotinylation studies indicated that the inhibition of MRP4 internalization was responsible for these results. Immunocytochemistry and cell surface biotinylation studies using COS-1 cells showed that SNX27 localized to both the early endosome and the plasma membrane. These data suggest that SNX27 interacts with MRP4 near the plasma membrane and promotes endocytosis of MRP4 and thereby negatively regulates its cell surface expression and transport function.
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Affiliation(s)
- Hisamitsu Hayashi
- Laboratory of Molecular Pharmacokinetics, Department of Medical Pharmaceutics, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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15
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Abstract
Dopamine is an important regulator of systemic blood pressure via multiple mechanisms. It affects fluid and electrolyte balance by its actions on renal hemodynamics and epithelial ion and water transport and by regulation of hormones and humoral agents. The kidney synthesizes dopamine from circulating or filtered L-DOPA independently from innervation. The major determinants of the renal tubular synthesis/release of dopamine are probably sodium intake and intracellular sodium. Dopamine exerts its actions via two families of cell surface receptors, D1-like receptors comprising D1R and D5R, and D2-like receptors comprising D2R, D3R, and D4R, and by interactions with other G protein-coupled receptors. D1-like receptors are linked to vasodilation, while the effect of D2-like receptors on the vasculature is variable and probably dependent upon the state of nerve activity. Dopamine secreted into the tubular lumen acts mainly via D1-like receptors in an autocrine/paracrine manner to regulate ion transport in the proximal and distal nephron. These effects are mediated mainly by tubular mechanisms and augmented by hemodynamic mechanisms. The natriuretic effect of D1-like receptors is caused by inhibition of ion transport in the apical and basolateral membranes. D2-like receptors participate in the inhibition of ion transport during conditions of euvolemia and moderate volume expansion. Dopamine also controls ion transport and blood pressure by regulating the production of reactive oxygen species and the inflammatory response. Essential hypertension is associated with abnormalities in dopamine production, receptor number, and/or posttranslational modification.
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Affiliation(s)
- Ines Armando
- Children’s National Medical Center—Center for Molecular Physiology Research, Washington, District of Columbia
| | - Van Anthony M. Villar
- Children’s National Medical Center—Center for Molecular Physiology Research, Washington, District of Columbia
| | - Pedro A. Jose
- Children’s National Medical Center—Center for Molecular Physiology Research, Washington, District of Columbia
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16
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Zhang L, Guo F, Guo H, Wang H, Zhang Z, Liu X, Shi X, Gou X, Su Q, Yin J, Wang Y. The paradox of dopamine and angiotensin II-mediated Na(+), K(+)-ATPase regulation in renal proximal tubules. Clin Exp Hypertens 2011; 32:464-8. [PMID: 21029011 DOI: 10.3109/10641963.2010.496516] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Accumulated studies reported that the natruretic dopamine (DA) and the anti-natruretic angiotensin II (Ang II) represent an important mechanism to regulate renal Na(+) and water excretion through intracellular secondary messengers to inhibit or activate renal proximal tubule (PT) Na(+), K(+)-ATPase (NKA). The antagonistic actions were mediated by the phosphorylation of different position of NKA α₁-subunit and different Pals-associated tight junction protein (PATJ) PDZ domains, the different protein kinase C (PKC) isoforms (PKC-β, PKC-ζ), the common adenylyl cyclase (AC) pathway, and the crosstalk and balance between DA and Ang II to NKA regulation. Besides, Ang II-mediated NKA modulation has bi-phasic effects.
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Affiliation(s)
- Linan Zhang
- Pharmacy Department, Hebei University of Science and Technology, Hebei, China.
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17
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Pierre SV, Belliard A, Sottejeau Y. Modulation of Na(+)-K(+)-ATPase cell surface abundance through structural determinants on the α1-subunit. Am J Physiol Cell Physiol 2010; 300:C42-8. [PMID: 21048163 DOI: 10.1152/ajpcell.00386.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Through their ion-pumping and non-ion-pumping functions, Na(+)-K(+)-ATPase protein complexes at the plasma membrane are critical to intracellular homeostasis and to the physiological and pharmacological actions of cardiotonic steroids. Alteration of the abundance of Na(+)-K(+)-ATPase units at the cell surface is one of the mechanisms for Na(+)-K(+)-ATPase regulation in health and diseases that has been closely examined over the past few decades. We here summarize these findings, with emphasis on studies that explicitly tested the involvement of defined regions or residues on the Na(+)-K(+)-ATPase α1 polypeptide. We also report new findings on the effect of manipulating Na(+)-K(+)-ATPase membrane abundance by targeting one of these defined regions: a dileucine motif of the form [D/E]XXXL[L/I]. In this study, opossum kidney cells stably expressing rat α1 Na(+)-K(+)-ATPase or a mutant where the motif was disrupted (α1-L499V) were exposed to 30 min of substrate/coverslip-induced-ischemia followed by reperfusion (I-R). Biotinylation studies suggested that I-R itself acted as an inducer of Na(+)-K(+)-ATPase internalization and that surface expression of the mutant was higher than the native Na(+)-K(+)-ATPase before and after ischemia. Annexin V/propidium iodide staining and lactate dehydrogenase release suggested that I-R injury was reduced in α1-L499V-expressing cells compared with α1-expressing cells. Hence, modulation of Na(+)-K(+)-ATPase cell surface abundance through structural determinants on the α-subunit is an important mechanism of regulation of cellular Na(+)-K(+)-ATPase in various physiological and pathophysiological conditions, with a significant impact on cell survival in face of an ischemic stress.
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Affiliation(s)
- Sandrine V Pierre
- Department of Physiology and Pharmacology, University of Toledo College of Medicine, Ohio 43614-2598, USA.
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18
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Sottejeau Y, Belliard A, Duran MJ, Pressley TA, Pierre SV. Critical role of the isoform-specific region in alpha1-Na,K-ATPase trafficking and protein Kinase C-dependent regulation. Biochemistry 2010; 49:3602-10. [PMID: 20302352 DOI: 10.1021/bi9021999] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The isoform-specific region (ISR) is a region of structural heterogeneity among the four isoforms of the catalytic alpha-subunit of the Na,K-ATPase and an important structural determinant for isoform-specific functions. In the present study, we examined the role of a potential dileucine clathrin adaptor recognition motif [DE]XXXL[LI] embedded within the alpha1-ISR. To this end, a rat alpha1 construct where leucine 499 was replaced by a valine (as found in the alpha2 isoform sequence) was compared to wild-type rat alpha1 after stable expression in opossum kidney cells. Total Na,K-ATPase expression, activity, or in situ (86)Rb(+) transport was not affected by the L499V mutation. However, surface Na,K-ATPase expression was nearly doubled. This increase was associated with a reduced rate of internalization from the cell surface of about 50% after a 4 h chase and became undetectable if clathrin-coated pit-mediated trafficking was blocked with chlorpromazine. Further, PKC-induced stimulation of Na,K-ATPase-mediated (86)Rb(+) uptake was doubled in mutant-expressing cells, comparable to the chimera containing the intact alpha2-ISR. Similar results were observed when the potential motif was disrupted by means of an E495S mutation. These findings suggest that a dileucine motif embedded within the Na,K-ATPase alpha1-ISR plays a critical role in the surface expression of Na,K-ATPase alpha1 polypeptides at steady state and in the response to PKC activation.
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Affiliation(s)
- Yoann Sottejeau
- Department of Physiology and Pharmacology, University of Toledo College of Medicine, Toledo, Ohio 43614, USA
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19
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Jaitovich A, Bertorello AM. Intracellular sodium sensing: SIK1 network, hormone action and high blood pressure. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1140-9. [PMID: 20347966 DOI: 10.1016/j.bbadis.2010.03.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 03/12/2010] [Accepted: 03/20/2010] [Indexed: 01/11/2023]
Abstract
Sodium is the main determinant of body fluid distribution. Sodium accumulation causes water retention and, often, high blood pressure. At the cellular level, the concentration and active transport of sodium is handled by the enzyme Na(+),K(+)-ATPase, whose appearance enabled evolving primitive cells to cope with osmotic stress and contributed to the complexity of mammalian organisms. Na(+),K(+)-ATPase is a platform at the hub of many cellular signaling pathways related to sensing intracellular sodium and dealing with its detrimental excess. One of these pathways relies on an intracellular sodium-sensor network with the salt-inducible kinase 1 (SIK1) at its core. When intracellular sodium levels rise, and after the activation of calcium-related signals, this network activates the Na(+),K(+)-ATPase and expel the excess of sodium from the cytosol. The SIK1 network also mediates sodium-independent signals that modulate the activity of the Na(+),K(+)-ATPase, like dopamine and angiotensin, which are relevant per se in the development of high blood pressure. Animal models of high blood pressure, with identified mutations in components of multiple pathways, also have alterations in the SIK1 network. The introduction of some of these mutants into normal cells causes changes in SIK1 activity as well. Some cellular processes related to the metabolic syndrome, such as insulin effects on the kidney and other tissues, also appear to involve the SIK1. Therefore, it is likely that this protein, by modulating active sodium transport and numerous hormonal responses, represents a "crossroad" in the development and adaptation to high blood pressure and associated diseases.
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Affiliation(s)
- Ariel Jaitovich
- Department of Medicine, Karolinska Institutet, Karolinska University Hospital-Solna, 171 76 Stockholm, Sweden.
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20
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Chen Z, Leibiger I, Katz AI, Bertorello AM. Pals-associated tight junction protein functionally links dopamine and angiotensin II to the regulation of sodium transport in renal epithelial cells. Br J Pharmacol 2009; 158:486-93. [PMID: 19563532 DOI: 10.1111/j.1476-5381.2009.00299.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Dopamine inhibits renal cell Na(+),K(+)-ATPase activity and cell sodium transport by promoting the internalization of active molecules from the plasma membrane, whereas angiotensin II (ATII) stimulates its activity by recruiting new molecules to the plasma membrane. They achieve such effects by activating multiple and distinct signalling molecules in a hierarchical manner. The purpose of this study was to investigate whether dopamine and ATII utilize scaffold organizer proteins as components of their signalling networks, in order to avoid deleterious cross talk. EXPERIMENTAL APPROACH Attention was focused on a multiple PDZ domain protein, Pals-associated tight junction protein (PATJ). Ectopic expression of PATJ in renal epithelial cells in culture was used to study its interaction with components of the dopamine signalling cascade. Similarly, expression of PATJ deletion mutants was employed to analyse its functional relevance during dopamine-, ATII- and insulin-dependent regulation of Na(+),K(+)-ATPase. KEY RESULTS Dopamine receptors and components of its signalling cascade mediating inhibition of Na(+),K(+)-ATPase interact with PATJ. Inhibition of Na(+),K(+)-ATPase by dopamine was prevented by expression of mutants of PATJ lacking PDZ domains 2, 4 or 5; whereas the stimulatory effect of ATII and insulin on Na(+),K(+)-ATPase was blocked by expression of PATJ lacking PDZ domains 1, 4 or 5. CONCLUSIONS AND IMPLICATIONS A multiple PDZ domain protein may add functionality to G protein-coupled and tyrosine kinase receptors signalling during regulation of Na(+),K(+)-ATPase. Signalling molecules and effectors can be integrated into a functional network by the scaffold organizer protein PATJ via its multiple PDZ domains.
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Affiliation(s)
- Z Chen
- Department of Medicine, Karolinska Institutet, Karolinska University Hospital-Solna, Stockholm, Sweden
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21
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Cinelli AR, Efendiev R, Pedemonte CH. Trafficking of Na-K-ATPase and dopamine receptor molecules induced by changes in intracellular sodium concentration of renal epithelial cells. Am J Physiol Renal Physiol 2008; 295:F1117-25. [PMID: 18701625 DOI: 10.1152/ajprenal.90317.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Most of the transepithelial transport of sodium in proximal tubules occurs through the coordinated action of the apical sodium/proton exchanger and the basolateral Na-K-ATPase. Hormones that regulate proximal tubule sodium excretion regulate the activities of these proteins. We have previously demonstrated that the level of intracellular sodium concentration modulates the regulation of Na-K-ATPase activity by angiotensin II and dopamine. An increase of a few millimolars in intracellular sodium concentration leads to increased Na-K-ATPase activity without a statistically significant increase in the number of plasma membrane Na-K-ATPase molecules, as determined by cell surface protein biotinylation. Using total internal reflection fluorescence, we detected an increased number of Na-K-ATPase molecules in cytosolic compartments adjacent to the plasma membrane, suggesting that the increased intracellular sodium concentration induces a movement of Na-K-ATPase molecules toward the plasma membrane. While intracellular compartments containing Na-K-ATPase molecules are very close to the plasma membrane, compartments containing type 1 dopamine receptors (D1Rs) are distributed in different parts of the cell cytosol. Fluorescence determinations indicate that an increased intracellular sodium concentration induces the increased colocalization of dopamine receptors with Na-K-ATPase molecules in the region of the plasma membrane. We propose that under in vivo conditions, in response to a sodium load in the lumen of proximal tubules, an increased level of intracellular sodium in epithelial cells is an early event that triggers the cellular response that leads to dopamine inhibition of proximal tubule sodium reabsorption.
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Affiliation(s)
- Angel R Cinelli
- Department of Anatomy and Cell Biology, State University of New York at Brooklyn, Brooklyn, NY, USA
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22
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Efendiev R, Budu CE, Bertorello AM, Pedemonte CH. G-protein-coupled receptor-mediated traffic of Na,K-ATPase to the plasma membrane requires the binding of adaptor protein 1 to a Tyr-255-based sequence in the alpha-subunit. J Biol Chem 2008; 283:17561-7. [PMID: 18420589 PMCID: PMC2427321 DOI: 10.1074/jbc.m709260200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 04/15/2008] [Indexed: 11/06/2022] Open
Abstract
Motion of integral membrane proteins to the plasma membrane in response to G-protein-coupled receptor signals requires selective cargo recognition motifs that bind adaptor protein 1 and clathrin. Angiotensin II, through the activation of AT1 receptors, promotes the recruitment to the plasma membrane of Na,K-ATPase molecules from intracellular compartments. We present evidence to demonstrate that a tyrosine-based sequence (IVVY-255) present within the Na,K-ATPase alpha1-subunit is involved in the binding of adaptor protein 1. Mutation of Tyr-255 to a phenylalanine residue in the Na,K-ATPase alpha1-subunit greatly reduces the angiotensin II-dependent activation of Na,K-ATPase, recruitment of Na,K-ATPase molecules to the plasma membrane, and association of adaptor protein 1 with Na,K-ATPase alpha1-subunit molecules. To determine protein-protein interaction, we used fluorescence resonance energy transfer between fluorophores attached to the Na,K-ATPase alpha1-subunit and adaptor protein 1. Although angiotensin II activation of AT1 receptors induces a significant increase in the level of fluorescence resonance energy transfer between the two molecules, this effect was blunted in cells expressing the Tyr-255 mutant. Thus, results from different methods and techniques suggest that the Tyr-255-based sequence within the NKA alpha1-subunit is the site of adaptor protein 1 binding in response to the G-protein-coupled receptor signals produced by angiotensin II binding to AT1 receptors.
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Affiliation(s)
- Riad Efendiev
- College of Pharmacy, University of Houston, Houston, Texas 77204, USA.
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23
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Lecuona E, Trejo HE, Sznajder JI. Regulation of Na,K-ATPase during acute lung injury. J Bioenerg Biomembr 2008; 39:391-5. [PMID: 17972021 DOI: 10.1007/s10863-007-9102-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A hallmark of acute lung injury is the accumulation of a protein rich edema which impairs gas exchange and leads to hypoxemia. The resolution of lung edema is effected by active sodium transport, mostly contributed by apical Na(+) channels and the basolateral located Na,K-ATPase. It has been reported that the decrease of Na,K-ATPase function seen during lung injury is due to its endocytosis from the cell plasma membrane into intracellular pools. In alveolar epithelial cells exposed to severe hypoxia, we have reported that increased production of mitochondrial reactive oxygen species leads to Na,K-ATPase endocytosis and degradation. We found that this regulated process follows what is referred as the Phosphorylation-Ubiquitination-Recognition-Endocytosis-Degradation (PURED) pathway. Cells exposed to hypoxia generate reactive oxygen species which activate PKC zeta which in turn phosphorylates the Na,K-ATPase at the Ser18 residue in the N-terminus of the alpha1-subunit leading the ubiquitination of any of the four lysines (K16, K17, K19, K20) adjacent to the Ser18 residue. This process promotes the alpha1-subunit recognition by the mu2 subunit of the adaptor protein-2 and its endocytosis trough a clathrin dependent mechanism. Finally, the ubiquitinated Na,K-ATPase undergoes degradation via a lysosome/proteasome dependent mechanism.
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Affiliation(s)
- Emilia Lecuona
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Zeng C, Armando I, Luo Y, Eisner GM, Felder RA, Jose PA. Dysregulation of dopamine-dependent mechanisms as a determinant of hypertension: studies in dopamine receptor knockout mice. Am J Physiol Heart Circ Physiol 2008; 294:H551-69. [PMID: 18083900 PMCID: PMC4029502 DOI: 10.1152/ajpheart.01036.2007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Dopamine plays an important role in the pathogenesis of hypertension by regulating epithelial sodium transport and by interacting with vasoactive hormones/humoral factors, such as aldosterone, angiotensin, catecholamines, endothelin, oxytocin, prolactin pro-opiomelancortin, reactive oxygen species, renin, and vasopressin. Dopamine receptors are classified into D(1)-like (D(1) and D(5)) and D(2)-like (D(2), D(3), and D(4)) subtypes based on their structure and pharmacology. In recent years, mice deficient in one or more of the five dopamine receptor subtypes have been generated, leading to a better understanding of the physiological role of each of the dopamine receptor subtypes. This review summarizes the results from studies of various dopamine receptor mutant mice on the role of individual dopamine receptor subtypes and their interactions with other G protein-coupled receptors in the regulation of blood pressure.
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MESH Headings
- Animals
- Blood Pressure/genetics
- Blood Pressure/physiology
- Dopamine/physiology
- Hypertension/genetics
- Hypertension/physiopathology
- Mice
- Mice, Knockout
- Receptors, Dopamine/genetics
- Receptors, Dopamine/physiology
- Receptors, Dopamine D1/genetics
- Receptors, Dopamine D1/physiology
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/physiology
- Receptors, Dopamine D3/genetics
- Receptors, Dopamine D3/physiology
- Receptors, Dopamine D4/genetics
- Receptors, Dopamine D4/physiology
- Receptors, Dopamine D5/genetics
- Receptors, Dopamine D5/physiology
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Affiliation(s)
- Chunyu Zeng
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing City 400042, People's Republic of China.
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25
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Regulation of sodium pump endocytosis by cardiotonic steroids: Molecular mechanisms and physiological implications. ACTA ACUST UNITED AC 2007; 14:171-81. [PMID: 17961998 DOI: 10.1016/j.pathophys.2007.09.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We have previously shown that ouabain and other cardiotonic steroids interact with the plasmalemmal Na/K-ATPase and cause a time and dose dependent endocytosis of the Na/K-ATPase. This endocytosis is demonstrable using fluorescence imaging as well as conventional biochemical and biophysical cell separation methods. In proximal tubule cells, this process appears to regulate the density of basolateral Na/K-ATPase expression directly as well as indirectly modulate transepithelial sodium transport. Work with genetic manipulations, as well as pharmacological agents with cell culture models, have demonstrated that the cardiotonic steroid stimulated endocytosis of the plasmalemmal Na/K-ATPase requires caveolin and clathrin as well as the activation of c-Src, transactivation of the EGFR and activation of PI3K. Interestingly c-Src, EGFR and ERK1/2 all appear to be endocytosed along with the plasmalemmal Na/K-ATPase. These observations suggest a close analogy between a subset of plasmalemmal Na/K-ATPase and signaling companions with conventional receptor tyrosine kinases. While further studies are necessary to delineate the role of this endocytosis in the generation as well as the limit of signal transduction through the Na/K-ATPase signal cascade, we propose that it has an important role in the regulation of renal sodium handling as well as other important processes.
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26
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SIK1 is part of a cell sodium-sensing network that regulates active sodium transport through a calcium-dependent process. Proc Natl Acad Sci U S A 2007; 104:16922-7. [PMID: 17939993 DOI: 10.1073/pnas.0706838104] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In mammalian cells, active sodium transport and its derived functions (e.g., plasma membrane potential) are dictated by the activity of the Na(+),K(+)-ATPase (NK), whose regulation is essential for maintaining cell volume and composition, as well as other vital cell functions. Here we report the existence of a salt-inducible kinase-1 (SIK1) that associates constitutively with the NK regulatory complex and is responsible for increases in its catalytic activity following small elevations in intracellular sodium concentrations. Increases in intracellular sodium are paralleled by elevations in intracellular calcium through the reversible Na(+)/Ca(2+) exchanger, leading to the activation of SIK1 (Thr-322 phosphorylation) by a calcium calmodulin-dependent kinase. Activation of SIK1 results in the dephosphorylation of the NK alpha-subunit and an increase in its catalytic activity. A protein phosphatase 2A/phosphatase methylesterase-1 (PME-1) complex, which constitutively associates with the NK alpha-subunit, is activated by SIK1 through phosphorylation of PME-1 and its dissociation from the complex. These observations illustrate the existence of a distinct intracellular signaling network, with SIK1 at its core, which is triggered by a monovalent cation (Na(+)) and links sodium permeability to its active transport.
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Efendiev R, Das-Panja K, Cinelli AR, Bertorello AM, Pedemonte CH. Localization of intracellular compartments that exchange Na,K-ATPase molecules with the plasma membrane in a hormone-dependent manner. Br J Pharmacol 2007; 151:1006-13. [PMID: 17533417 PMCID: PMC2042937 DOI: 10.1038/sj.bjp.0707304] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Dopamine is a major regulator of sodium reabsorption in proximal tubule epithelia. By binding to D1-receptors, dopamine induces endocytosis of plasma membrane Na,K-ATPase, resulting in a reduced capacity of the cells to transport sodium, thus contributing to natriuresis. We have previously demonstrated several aspects of the molecular mechanism by which dopamine induces Na,K-ATPase endocytosis; however, the location of intracellular compartments containing Na,K-ATPase molecules has not been identified. EXPERIMENTAL APPROACH In this study, we used different approaches to determine the localization of Na,K-ATPase-containing intracellular compartments. By expression of fluorescent-tagged Na,K-ATPase molecules in opossum kidney cells, a cell culture model of proximal tubule epithelia, we used fluorescence microscopy to determine cellular distribution of the fluorescent molecules and the effects of dopamine on this distribution. By labelling cell surface Na,K-ATPase molecules from the cell exterior with either biotin or an epitope-tagged antibody, we determined the localization of the tagged Na,K-ATPase molecules after endocytosis induced by dopamine. KEY RESULTS In cells expressing fluorescent-tagged Na,K-ATPase molecules, there were intracellular compartments containing Na,K-ATPase molecules. These compartments were in very close proximity to the plasma membrane. Upon treatment of the cells with dopamine, the fluorescence labelling of these compartments was increased. The labelling of these compartments was also observed when the endocytosis of biotin- or antibody-tagged plasma membrane Na,K-ATPase molecules was induced by dopamine. CONCLUSIONS AND IMPLICATIONS The intracellular compartments containing Na,K-ATPase molecules are located just underneath the plasma membrane.
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Affiliation(s)
- R Efendiev
- College of Pharmacy, University of Houston, 4800 Calhoun Road, Houston, TX 77204, USA.
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Nesher M, Shpolansky U, Rosen H, Lichtstein D. The digitalis-like steroid hormones: new mechanisms of action and biological significance. Life Sci 2007; 80:2093-2107. [PMID: 17499813 DOI: 10.1016/j.lfs.2007.03.013] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 03/08/2007] [Accepted: 03/14/2007] [Indexed: 12/25/2022]
Abstract
Digitalis-like compounds (DLC) are a family of steroid hormones synthesized in and released from the adrenal gland. DLC, the structure of which resembles that of plant cardiac glycosides, bind to and inhibit the activity of the ubiquitous cell surface enzyme Na(+), K(+)-ATPase. However, there is a large body of evidence suggesting that the regulation of ion transport by Na(+), K(+)-ATPase is not the only physiological role of DLC. The binding of DLC to Na(+), K(+)-ATPase induces the activation of various signal transduction cascades that activate changes in intracellular Ca(++) homeostasis, and in specific gene expression. These, in turn, stimulate endocytosis and affect cell growth and proliferation. At the systemic level, DLC were shown to be involved in the regulation of major physiological parameters including water and salt homeostasis, cardiac contractility and rhythm, systemic blood pressure and behavior. Furthermore, the DLC system has been implicated in several pathological conditions, including cardiac arrhythmias, hypertension, cancer and depressive disorders. This review evaluates the evidence for the different aspects of DLC action and delineates open questions in the field.
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Affiliation(s)
- Maoz Nesher
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Uri Shpolansky
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Haim Rosen
- The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - David Lichtstein
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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Rosskopf D, Schürks M, Rimmbach C, Schäfers R. Genetics of arterial hypertension and hypotension. Naunyn Schmiedebergs Arch Pharmacol 2007; 374:429-69. [PMID: 17262198 DOI: 10.1007/s00210-007-0133-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 12/22/2006] [Indexed: 01/13/2023]
Abstract
Human hypertension affects affects more than 20% of the adult population in industrialized countries, and it is implicated in millions of deaths worldwide each year from stroke, heart failure and ischemic heart disease. Available evidence suggests a major genetic impact on blood pressure regulation. Studies in monogenic hypertension revealed that renal salt and volume regulation systems are predominantly involved in the genesis of these disorders. Mutations here affect the synthesis of mineralocorticoids, the function of the mineralocorticoid receptor, epithelial sodium channels and their regulation by a new class of kinases, termed WNK kinases. It has been learned from monogenic hypotension that almost all ion transporters involved in the renal uptake of Na(+) have a major impact on blood pressure regulation. For essential hypertension as a complex disease, many candidate genes have been analysed. These include components of the renin-angiotensin-aldosterone system, adducin, beta-adrenoceptors, G protein subunits, regulators of G protein signalling (RGS) proteins, Rho kinases and G protein receptor kinases. At present, the individual impact of common polymorphisms in these genes on the observed blood pressure variation, on risk for stroke and as predictors of antihypertensive responses remains small and clinically irrelevant. Nevertheless, these studies have greatly augmented our knowledge on the regulation of renal functions, cellular signal transduction and the integration of both. Together, this provides the basis for the identification of novel drug targets and, hopefully, innovative antihypertensive drugs.
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Affiliation(s)
- Dieter Rosskopf
- Department Pharmacology, Research Center for Pharmacology and Experimental Therapeutics, Ernst-Moritz-Arndt-University Greifswald, Friedrich Loeffler Str. 23d, 17487 Greifswald, Germany.
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Dada LA, Sznajder JI. Hypoxic Inhibition of Alveolar Fluid Reabsorption. HYPOXIA AND THE CIRCULATION 2007; 618:159-68. [DOI: 10.1007/978-0-387-75434-5_12] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Comellas AP, Dada LA, Lecuona E, Pesce LM, Chandel NS, Quesada N, Budinger GRS, Strous GJ, Ciechanover A, Sznajder JI. Hypoxia-mediated degradation of Na,K-ATPase via mitochondrial reactive oxygen species and the ubiquitin-conjugating system. Circ Res 2006; 98:1314-22. [PMID: 16614303 DOI: 10.1161/01.res.0000222418.99976.1d] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We set out to determine whether cellular hypoxia, via mitochondrial reactive oxygen species, promotes Na,K-ATPase degradation via the ubiquitin-conjugating system. Cells exposed to 1.5% O2 had a decrease in Na,K-ATPase activity and oxygen consumption. The total cell pool of alpha1 Na,K-ATPase protein decreased on exposure to 1.5% O2 for 30 hours, whereas the plasma membrane Na,K-ATPase was 50% degraded after 2 hours of hypoxia, which was prevented by lysosome and proteasome inhibitors. When Chinese hamster ovary cells that exhibit a temperature-sensitive defect in E1 ubiquitin conjugation enzyme were incubated at 40 degrees C and 1.5% O2, the degradation of the alpha1 Na,K-ATPase was prevented. Exogenous reactive oxygen species increased the plasma membrane Na,K-ATPase degradation, whereas, in mitochondrial DNA deficient rho(0) cells and in cells transfected with small interfering RNA against Rieske iron sulfur protein, the hypoxia-mediated Na,K-ATPase degradation was prevented. The catalase/superoxide dismutase (SOD) mimetic (EUK-134) and glutathione peroxidase overexpression prevented the hypoxia-mediated Na,K-ATPase degradation and overexpression of SOD1, but not SOD2, partially inhibited the Na+ pump degradation. Accordingly, we provide evidence that during hypoxia, mitochondrial reactive oxygen species are necessary to degrade the plasma membrane Na,K-ATPase via the ubiquitin-conjugating system.
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Affiliation(s)
- Alejandro P Comellas
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Chen Z, Krmar RT, Dada L, Efendiev R, Leibiger IB, Pedemonte CH, Katz AI, Sznajder JI, Bertorello AM. Phosphorylation of adaptor protein-2 mu2 is essential for Na+,K+-ATPase endocytosis in response to either G protein-coupled receptor or reactive oxygen species. Am J Respir Cell Mol Biol 2006; 35:127-32. [PMID: 16498080 PMCID: PMC2658693 DOI: 10.1165/rcmb.2006-0044oc] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Activation of G protein-coupled receptor by dopamine and hypoxia-generated reactive oxygen species promote Na+,K+-ATPase endocytosis. This effect is clathrin dependent and involves the activation of protein kinase C (PKC)-zeta and phosphorylation of the Na+,K+-ATPase alpha-subunit. Because the incorporation of cargo into clathrin vesicles requires association with adaptor proteins, we studied whether phosphorylation of adaptor protein (AP)-2 plays a role in its binding to the Na+,K+-ATPase alpha-subunit and thereby in its endocytosis. Dopamine induces a time-dependent phosphorylation of the AP-2 mu2 subunit. Using specific inhibitors and dominant-negative mutants, we establish that this effect was mediated by activation of the adaptor associated kinase 1/PKC-zeta isoform. Expression of the AP-2 mu2 bearing a mutation in its phosphorylation site (T156A) prevented Na+,K+-ATPase endocytosis and changes in activity induced by dopamine. Similarly, in lung alveolar epithelial cells, hypoxia-induced endocytosis of Na+,K+-ATPase requires the binding of AP-2 to the tyrosine-based motif (Tyr-537) located in the Na+,K+-ATPase alpha-subunit, and this effect requires phosphorylation of the AP-2 mu2 subunit. We conclude that phosphorylation of AP-2 mu2 subunit is essential for Na+,K+-ATPase endocytosis in response to a variety of signals, such as dopamine or reactive oxygen species.
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Affiliation(s)
- Zongpei Chen
- Department of Medicine, Membrane Signaling Networks, Karolinska Institutet, Karolinska Hospital, Stockholm, Sweden
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Abstract
The Na,K-pump was discovered about 50 years ago. Since then there has been a methodic investigation of its structure and functional characteristics. The development of the Albers-Post model for the transport cycle was a milestone that provided the framework for detailed understanding of the transport process. The pump is composed of 2 subunits that exist in the membrane as an alphabeta heterodimer. All known enzymatic functions of the pump occur through the alpha subunit. Although necessary for activity, the complete role of the beta subunit is not understood fully. Numerous studies have established that the alphabeta protomer is the minimal functional unit needed to perform the Albers-Post reaction cycle. However, higher orders of aggregation [(alphabeta)n] are commonly detected. There is little evidence that oligomerization has functional consequence for ion transport. The Na+,K+-adenosine triphosphatase (ATPase) is a member of the P-type ATPase family of transporters. Proteins within this family have common amino acid sequence motifs that share functional characteristics and structure. Low-resolution 3-dimensional reconstruction of 2-dimensional crystal diffractions provide evidence for the similarity in tertiary structure of the alpha subunit and the Ca2+ATPase (a closely related P-type ATPase). The spatial location of the beta subunit also is obvious in these reconstructions. Recent high-resolution reconstructions from 3-dimensional crystals of the Ca2+ATPase provide structural details at the atomic level. It now is possible to interpret structurally some of the key steps in the Albers-Post reaction. Some of these high-resolution interpretations are translatable to the Na+,K+-ATPase, but a high-resolution structure of the Na,K-pump is needed for the necessary details of those aspects that are unique to this transporter.
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Affiliation(s)
- Dwight W Martin
- Division of Hematology, Stony Brook University, Stony Brook, NY 11794-8151, USA.
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Bertorello AM, Sznajder JI. The dopamine paradox in lung and kidney epithelia: sharing the same target but operating different signaling networks. Am J Respir Cell Mol Biol 2005; 33:432-7. [PMID: 16234332 PMCID: PMC2715350 DOI: 10.1165/rcmb.2005-0297tr] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Stimulation of dopamine receptors in the lung or kidney epithelia has distinct and opposite effects on the function of Na,K-ATPase, which results in increased Na(+) absorption across the alveolar epithelium and increased sodium excretion via the kidney epithelium. In the lung, dopamine increases Na,K-ATPase by increasing cell basolateral surface expression of Na(+),K(+)-ATPase molecules, whereas in the kidney epithelia it decreases Na(+),K(+)-ATPase activity by removing active units from the plasma membrane by endocytosis. The opposite effects of dopamine over the same target (the Na(+),K(+)-ATPase) involve the activation of a distinct signaling network that it is target specific, and has a different spatial resolution. Understanding the specific signaling pathways involved in these actions of dopamine and their hierarchical organization may facilitate the drug discovery process that could lead to the design of new therapeutic approaches to clear lung edema in patients with acute lung injury and to decrease fluid overload during congestive heart failure and hypertension.
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Affiliation(s)
- Alejandro M Bertorello
- Department of Medicine, Atherosclerosis Research Unit, Membrane Signaling Networks, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
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Pedemonte CH, Efendiev R, Bertorello AM. Inhibition of Na,K-ATPase by Dopamine in Proximal Tubule Epithelial Cells. Semin Nephrol 2005; 25:322-7. [PMID: 16139687 DOI: 10.1016/j.semnephrol.2005.03.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the current report we review the results that lay grounds for the model of intracellular sodium-mediated dopamine-induced endocytosis of Na,K-ATPase. Under conditions of a high salt diet, dopamine activates PKCzeta, which phosphorylates NKA alpha1 Ser-18. The phosphorylation produces a conformational change of alpha1 NH2-terminus, which through interaction with other domains of alpha1 exposes PI3K- and AP-2-binding domains. PI3K bound to the NKA alpha1 induces the recruitment and activation of other proteins involved in endocytosis, and PI3K-generated 3-phosphoinositides affect the local cytoskeleton and modify the biophysical conditions of the membrane for development of clathrin-coated pits. Plasma membrane phosphorylated NKA is internalized to specialized intracellular compartments where the NKA will be dephosphorylated. The NKA internalization results in a reduced Na+ transport by proximal tubule epithelial cells.
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Periyasamy SM, Liu J, Tanta F, Kabak B, Wakefield B, Malhotra D, Kennedy DJ, Nadoor A, Fedorova OV, Gunning W, Xie Z, Bagrov AY, Shapiro JI. Salt loading induces redistribution of the plasmalemmal Na/K-ATPase in proximal tubule cells. Kidney Int 2005; 67:1868-77. [PMID: 15840034 DOI: 10.1111/j.1523-1755.2005.00285.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND We have reported that digitalis-like substances (cardiotonic steroids), including marinobufagenin (MBG), induce endocytosis of the plasmalemmal Na/K-ATPase in LLC-PK1 cells. The current report addresses the potential relevance of plasmalemmal Na/K-ATPase redistribution to in vivo salt handling. METHODS Male Sprague-Dawley rats were given 1 week of a high salt (4.0% NaCl) or normal salt (0.4% NaCl) diet. Urinary sodium excretion, as well as MBG excretion, was monitored, and proximal tubules were isolated using a Percoll gradient method. Tubular (86)Rb uptake, Na/K-ATPase enzymatic activity, and Na/K-ATPase alpha1 subunit density were determined. RESULTS The high salt diet increased urinary sodium (17.8 +/- 1.8 vs. 2.5 +/- 0.3 mEq/day, P < 0.01) and MBG excretion (104 +/- 12 vs. 26 +/- 4 pmol/day), and decreased proximal tubular (86)Rb uptake (0.44 +/- 0.07 vs. 1.00 +/- 0.10, P < 0.01) and Na/K-ATPase enzymatic activity (5.1 +/- 1.1 vs. 9.9 +/- 1.6 micromol/mg pr/hr, P < 0.01) relative to the normal diet. Proximal tubular Na/K-ATPase alpha1 protein density was decreased in the plasmalemma fraction but increased in both early and late endosomes following the high salt diet. In rats fed a high salt diet, anti-MBG antibody caused a 60% reduction in urinary sodium excretion, substantial increases in proximal tubule (86)Rb uptake, and Na/K-ATPase enzymatic activity, as well as significant decreases in the early and late endosomal Na/K-ATPase alpha1 protein content. CONCLUSION These data suggest that redistribution of the proximal tubule Na/K-ATPase in response to endogenous cardiotonic steroids plays an important role in renal adaptation to salt loading.
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Efendiev R, Chen Z, Krmar RT, Uhles S, Katz AI, Pedemonte CH, Bertorello AM. The 14-3-3 protein translates the NA+,K+-ATPase {alpha}1-subunit phosphorylation signal into binding and activation of phosphoinositide 3-kinase during endocytosis. J Biol Chem 2005; 280:16272-7. [PMID: 15722354 DOI: 10.1074/jbc.m500486200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clathrin-dependent endocytosis of Na(+),K(+)-ATPase molecules in response to G protein-coupled receptor signals is triggered by phosphorylation of the alpha-subunit and the binding of phosphoinositide 3-kinase. In this study, we describe a molecular mechanism linking phosphorylation of Na(+),K(+)-ATPase alpha-subunit to binding and activation of phosphoinositide 3-kinase. Co-immunoprecipitation studies, as well as experiments using confocal microscopy, revealed that dopamine favored the association of 14-3-3 protein with the basolateral plasma membrane and its co-localization with the Na(+),K(+)-ATPase alpha-subunit. The functional relevance of this interaction was established in opossum kidney cells expressing a 14-3-3 dominant negative mutant, where dopamine failed to decrease Na(+),K(+)-ATPase activity and to promote its endocytosis. The phosphorylated Ser-18 residue within the alpha-subunit N terminus is critical for 14-3-3 binding. Activation of phosphoinositide 3-kinase by dopamine during Na(+),K(+)-ATPase endocytosis requires the binding of the kinase to a proline-rich domain within the alpha-subunit, and this effect was blocked by the presence of a 14-3-3 dominant negative mutant. Thus, the 14-3-3 protein represents a critical linking mechanism for recruiting phosphoinositide 3-kinase to the site of Na(+),K(+)-ATPase endocytosis.
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Affiliation(s)
- Riad Efendiev
- Department of Medicine, Atherosclerosis Research Unit, Membrane Signaling Networks, Karolinska Institutet, Karolinska University Hospital-Solna, S-171 76 Stockholm, Sweden
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Liu J, Kesiry R, Periyasamy SM, Malhotra D, Xie Z, Shapiro JI. Ouabain induces endocytosis of plasmalemmal Na/K-ATPase in LLC-PK1 cells by a clathrin-dependent mechanism. Kidney Int 2005; 66:227-41. [PMID: 15200429 DOI: 10.1111/j.1523-1755.2004.00723.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND We have demonstrated that ouabain causes dose- and time-dependent decreases in (86)Rb uptake in porcine proximal tubular (LLC-PK1) cells. The present study addresses the molecular mechanisms involved in this process. METHODS Studies were performed with cultured LLC-PK1 and Src family kinase deficient (SYF) cells. RESULTS We found that 50 nmol/L ouabain applied to the basal, but not apical, aspect for 12 hours caused decreases in the plasmalemmal Na/K-ATPase. This loss of plasmalemmal Na/K-ATPase reverses completely within 12 to 24 hours after removal of ouabain. Ouabain also increased the Na/K-ATPase content in both early and late endosomes, activated phosphatidylinositol 3-kinase (PI(3)K), and also caused a translocation of some Na/K-ATPase to the nucleus. Immunofluorescence demonstrated that the Na/K-ATPase colocalized with clathrin both before and after exposure to ouabain, and immunoprecipitation experiments confirmed that ouabain stimulated interactions among the Na/K-ATPase, adaptor protein-2 (AP-2), and clathrin. Potassium (K) depletion, chlorpromazine, or PI(3)K inhibition all significantly attenuated this ouabain-induced endocytosis. Inhibition of the ouabain-activated signaling process through Src by 4-Amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) significantly attenuated ouabain-induced endocytosis. Moreover, experiments performed in SYF cells demonstrated that ouabain induced increases in the endocytosis of the Na/K-ATPase when Src was reconstituted (SYF+), but not in the Src-deficient (SYF-) cells. CONCLUSION These data demonstrate that ouabain stimulates a clathrin-dependent endocytosis pathway that translocates the Na/K-ATPase to intracellular compartments, thus suggesting a potential role of endocytosis in ouabain-induced signal transduction as well as proximal tubule sodium handling.
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Affiliation(s)
- Jiang Liu
- The Department of Medicine, Medical College of Ohio, Toledo, Ohio, USA
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Efendiev R, Krmar RT, Ogimoto G, Zwiller J, Tripodi G, Katz AI, Bianchi G, Pedemonte CH, Bertorello AM. Hypertension-linked mutation in the adducin alpha-subunit leads to higher AP2-mu2 phosphorylation and impaired Na+,K+-ATPase trafficking in response to GPCR signals and intracellular sodium. Circ Res 2004; 95:1100-8. [PMID: 15528469 DOI: 10.1161/01.res.0000149570.20845.89] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Alpha-adducin polymorphism in humans is associated with abnormal renal sodium handling and high blood pressure. The mechanisms by which mutations in adducin affect the renal set point for sodium excretion are not known. Decreases in Na+,K+-ATPase activity attributable to endocytosis of active units in renal tubule cells by dopamine regulates sodium excretion during high-salt diet. Milan rats carrying the hypertensive adducin phenotype have a higher renal tubule Na+,K+-ATPase activity, and their Na+,K+-ATPase molecules do not undergo endocytosis in response to dopamine as do those of the normotensive strain. Dopamine fails to promote the interaction between adaptins and the Na+,K+-ATPase because of adaptin-mu2 subunit hyperphosphorylation. Expression of the hypertensive rat or human variant of adducin into normal renal epithelial cells recreates the hypertensive phenotype with higher Na+,K+-ATPase activity, mu2-subunit hyperphosphorylation, and impaired Na+,K+-ATPase endocytosis. Thus, increased renal Na+,K+-ATPase activity and altered sodium reabsorption in certain forms of hypertension could be attributed to a mutant form of adducin that impairs the dynamic regulation of renal Na+,K+-ATPase endocytosis in response to natriuretic signals.
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Affiliation(s)
- Riad Efendiev
- Department of Medicine, Atherosclerosis Research Unit, Membrane Signaling Networks, Karolinska Institutet, Karolinska University Hospital, S-171 76 Stockholm, Sweden
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Khundmiri SJ, Bertorello AM, Delamere NA, Lederer ED. Clathrin-mediated Endocytosis of Na+,K+-ATPase in Response to Parathyroid Hormone Requires ERK-dependent Phosphorylation of Ser-11 within the α1-Subunit. J Biol Chem 2004; 279:17418-27. [PMID: 14976217 DOI: 10.1074/jbc.m311715200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parathyroid hormone (PTH) inhibits Na(+),K(+)-ATPase activity through protein kinase C- (PKC) and extracellular signal-regulated kinase- (ERK) dependent pathways and increases serine phosphorylation of the alpha(1)-subunit. To determine whether specific serine phosphorylation sites within the Na(+),K(+)-ATPase alpha(1)-subunit are involved in the Na(+),K(+)-ATPase responses to PTH, we examined the effect of PTH in opossum kidney cells stably transfected with wild type rat Na(+),K(+)-ATPase alpha(1)-subunit (WT), serine 11 to alanine mutant alpha(1)-subunit (S11A), or serine 18 to alanine mutant alpha(1)-subunit (S18A). PTH increased phosphorylation and endocytosis of the Na(+),K(+)-ATPase alpha(1)-subunit into clathrin-coated vesicles in cells transfected with WT and S18A rat Na(+),K(+)-ATPase alpha(1)-subunits. PTH did not increase the level of phosphorylation or stimulate translocation of Na(+),K(+)-ATPase alpha(1)-subunits into clathrin-coated vesicles in cells transfected with the S11A mutant. PTH inhibited ouabain-sensitive (86)Rb uptake and Na(+),K(+)-ATPase activity (ouabain-sensitive ATP hydrolysis) in WT- and S18A-transfected opossum kidney cells but not in S11A-transfected cells. Pretreatment of the cells with the PKC inhibitors and ERK inhibitor blocked PTH inhibition of (86)Rb uptake, Na(+),K(+)-ATPase activity, alpha(1)-subunit phosphorylation, and endocytosis in WT and S18A cells. Consistent with the notion that ERK phosphorylates Na(+),K(+)-ATPase alpha(1)-subunit, ERK was shown to be capable of causing phosphorylation of Na(+),K(+)-ATPase alpha(1)-subunit immunoprecipitated from WT and S18A but not from S11A-transfected cells. These results suggest that PTH regulates Na(+),K(+)-ATPase by PKC and ERK-dependent alpha(1)-subunit phosphorylation and that the phosphorylation requires the expression of a serine at the 11 position of the Na(+),K(+)-ATPase alpha(1)-subunit.
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Efendiev R, Budu CE, Cinelli AR, Bertorello AM, Pedemonte CH. Intracellular Na+ regulates dopamine and angiotensin II receptors availability at the plasma membrane and their cellular responses in renal epithelia. J Biol Chem 2003; 278:28719-26. [PMID: 12759348 DOI: 10.1074/jbc.m303741200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The balance and cross-talk between natruretic and antinatruretic hormone receptors plays a critical role in the regulation of renal Na+ homeostasis, which is a major determinant of blood pressure. Dopamine and angiotensin II have antagonistic effects on renal Na+ and water excretion, which involves regulation of the Na+,K+-ATPase activity. Herein we demonstrate that angiotensin II (Ang II) stimulation of AT1 receptors in proximal tubule cells induces the recruitment of Na+,K+-ATPase molecules to the plasmalemma, in a process mediated by protein kinase Cbeta and interaction of the Na+,K+-ATPase with adaptor protein 1. Ang II stimulation led to phosphorylation of the alpha subunit Ser-11 and Ser-18 residues, and substitution of these amino acids with alanine residues completely abolished the Ang II-induced stimulation of Na+,K+-ATPase-mediated Rb+ transport. Thus, for Ang II-dependent stimulation of Na+,K+-ATPase activity, phosphorylation of these serine residues is essential and may constitute a triggering signal for recruitment of Na+,K+-ATPase molecules to the plasma membrane. When cells were treated simultaneously with saturating concentrations of dopamine and Ang II, either activation or inhibition of the Na+,K+-ATPase activity was produced dependent on the intracellular Na+ concentration, which was varied in a very narrow physiological range (9-19 mm). A small increase in intracellular Na+ concentrations induces the recruitment of D1 receptors to the plasma membrane and a reduction in plasma membrane AT1 receptors. Thus, one or more proteins may act as an intracellular Na+ concentration sensor and play a major regulatory role on the effect of hormones that regulate proximal tubule Na+ reabsorption.
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Affiliation(s)
- Riad Efendiev
- College of Pharmacy, University of Houston, Houston, Texas 77204, USA
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42
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Hilge M, Siegal G, Vuister GW, Güntert P, Gloor SM, Abrahams JP. ATP-induced conformational changes of the nucleotide-binding domain of Na,K-ATPase. Nat Struct Mol Biol 2003; 10:468-74. [PMID: 12730684 DOI: 10.1038/nsb924] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2002] [Accepted: 03/31/2003] [Indexed: 11/08/2022]
Abstract
The Na,K-ATPase hydrolyzes ATP to drive the coupled extrusion and uptake of Na+ and K+ ions across the plasma membrane. Here, we report two high-resolution NMR structures of the 213-residue nucleotide-binding domain of rat alpha1 Na,K-ATPase, determined in the absence and the presence of ATP. The nucleotide binds in the anti conformation and shows a relative paucity of interactions with the protein, reflecting the low-affinity ATP-binding state. Binding of ATP induces substantial conformational changes in the binding pocket and in residues located in the hinge region connecting the N- and P-domains. Structural comparison with the Ca-ATPase stabilized by the inhibitor thapsigargin, E2(TG), and the model of the H-ATPase in the E1 form suggests that the observed changes may trigger the series of events necessary for the release of the K+ ions and/or disengagement of the A-domain, leading to the eventual transfer of the gamma-phosphate group to the invariant Asp369.
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Affiliation(s)
- Mark Hilge
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
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43
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Teixeira VL, Katz AI, Pedemonte CH, Bertorello AM. Isoform-specific regulation of Na+,K+-ATPase endocytosis and recruitment to the plasma membrane. Ann N Y Acad Sci 2003; 986:587-94. [PMID: 12763893 DOI: 10.1111/j.1749-6632.2003.tb07257.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Na(+),K(+)-ATPase traffics between the plasma membrane and intracellular compartments in response to acute changes in membrane receptor activation. These effects are accomplished by a time-dependent interaction of the Na(+),K(+)-ATPase alpha-subunit with specific intracellular signaling molecules either at the plasma membrane (endocytosis) or at the endosome's membranes (recruitment). Most of these studies have been performed in rat renal epithelial cells in which only the alpha(1) isoenzyme is present. Studies in neurons from the neostriatum in which all three alpha-subunit isoforms are present indicate that neurotransmitter-dependent regulation of Na(+),K(+)-ATPase activity displays isoform specificity and also suggest a more complex organization of the intracellular signaling networks controlling Na(+),K(+)-ATPase traffic in mammalian cells.
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Affiliation(s)
- Vera Lucas Teixeira
- Department of Medicine, Atherosclerosis Research Unit, Karolinska Institutet, Karolinska Hospital, 171 76 Stockholm, Sweden
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44
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Dada LA, Chandel NS, Ridge KM, Pedemonte C, Bertorello AM, Sznajder JI. Hypoxia-induced endocytosis of Na,K-ATPase in alveolar epithelial cells is mediated by mitochondrial reactive oxygen species and PKC-zeta. J Clin Invest 2003; 111:1057-64. [PMID: 12671055 PMCID: PMC152585 DOI: 10.1172/jci16826] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
During ascent to high altitude and pulmonary edema, the alveolar epithelial cells (AEC) are exposed to hypoxic conditions. Hypoxia inhibits alveolar fluid reabsorption and decreases Na,K-ATPase activity in AEC. We report here that exposure of AEC to hypoxia induced a time-dependent decrease of Na,K-ATPase activity and a parallel decrease in the number of Na,K-ATPase alpha(1) subunits at the basolateral membrane (BLM), without changing its total cell protein abundance. These effects were reversible upon reoxygenation and specific, because the plasma membrane protein GLUT1 did not decrease in response to hypoxia. Hypoxia caused an increase in mitochondrial reactive oxygen species (ROS) levels that was inhibited by antioxidants. Antioxidants prevented the hypoxia-mediated decrease in Na,K-ATPase activity and protein abundance at the BLM. Hypoxia-treated AEC deficient in mitochondrial DNA (rho(0) cells) did not have increased levels of ROS, nor was the Na,K-ATPase activity inhibited. Na,K-ATPase alpha(1) subunit was phosphorylated by PKC in hypoxia-treated AEC. In AEC treated with a PKC-zeta antagonist peptide or with the Na,K-ATPase alpha(1) subunit lacking the PKC phosphorylation site (Ser-18), hypoxia failed to decrease Na,K-ATPase abundance and function. Accordingly, we provide evidence that hypoxia decreases Na,K-ATPase activity in AEC by triggering its endocytosis through mitochondrial ROS and PKC-zeta-mediated phosphorylation of the Na,K-ATPase alpha(1) subunit.
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Affiliation(s)
- Laura A Dada
- Division of Pulmonary and Critical Care Medicine, Northwestern University, Chicago, Illinois 60611, USA
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45
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Al-Khalili L, Krook A, Chibalin AV. Phosphorylation of the Na+,K+-ATPase in skeletal muscle: potential mechanism for changes in pump cell-surface abundance and activity. Ann N Y Acad Sci 2003; 986:449-52. [PMID: 12763864 DOI: 10.1111/j.1749-6632.2003.tb07228.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In skeletal muscle, insulin stimulation leads to phosphorylation of Na(+),K(+)-ATPase alpha-subunits on both serine/threonine and tyrosine residues, translocation of Na(+),K(+)-ATPase molecules to the plasma membrane, and increased Na(+),K(+)-ATPase activity. The molecular nature of the tyrosine kinase that phosphorylates Na(+),K(+)-ATPase is not yet identified. In vitro phosphorylation experiments show that the alpha-subunit of Na(+),K(+)-ATPase from skeletal muscle is a substrate for the tyrosine-specific protein kinase c-src. Tyrosine phosphorylation of the alpha-subunits of Na(+),K(+)-ATPase may be an important mechanism for insulin-mediated regulation of Na(+),K(+)-ATPase translocation and activity.
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Affiliation(s)
- Lubna Al-Khalili
- Department of Clinical Physiology, Karolinska Hospital, 171 76 Stockholm, Sweden
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46
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Bertorello AM, Komarova Y, Smith K, Leibiger IB, Efendiev R, Pedemonte CH, Borisy G, Sznajder JI. Analysis of Na+,K+-ATPase motion and incorporation into the plasma membrane in response to G protein-coupled receptor signals in living cells. Mol Biol Cell 2003; 14:1149-57. [PMID: 12631730 PMCID: PMC151586 DOI: 10.1091/mbc.e02-06-0367] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Dopamine (DA) increases Na(+),K(+)-ATPase activity in lung alveolar epithelial cells. This effect is associated with an increase in Na(+),K(+)-ATPase molecules within the plasma membrane (). Analysis of Na(+),K(+)-ATPase motion was performed in real-time in alveolar cells stably expressing Na(+),K(+)-ATPase molecules carrying a fluorescent tag (green fluorescent protein) in the alpha-subunit. The data demonstrate a distinct (random walk) pattern of basal movement of Na(+),K(+)-ATPase-containing vesicles in nontreated cells. DA increased the directional movement (by 3.5 fold) of the vesicles and an increase in their velocity (by 25%) that consequently promoted the incorporation of vesicles into the plasma membrane. The movement of Na(+),K(+)-ATPase-containing vesicles and incorporation into the plasma membrane were microtubule dependent, and disruption of this network perturbed vesicle motion toward the plasma membrane and prevented the increase in the Na(+),K(+)-ATPase activity induced by DA. Thus, recruitment of new Na(+),K(+)-ATPase molecules into the plasma membrane appears to be a major mechanism by which dopamine increases total cell Na(+),K(+)-ATPase activity.
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Affiliation(s)
- Alejandro M Bertorello
- Department of Medicine, Atherosclerosis Research Unit, Karolinska Institutet, Karolinska Hospital, S-171 76 Stockholm, Sweden.
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Efendiev R, Yudowski GA, Zwiller J, Leibiger B, Katz AI, Berggren PO, Pedemonte CH, Leibiger IB, Bertorello AM. Relevance of dopamine signals anchoring dynamin-2 to the plasma membrane during Na+,K+-ATPase endocytosis. J Biol Chem 2002; 277:44108-14. [PMID: 12205083 DOI: 10.1074/jbc.m205173200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clathrin-dependent endocytosis of Na(+),K(+)-ATPase in response to dopamine regulates its catalytic activity in intact cells. Because fission of clathrin-coated pits requires dynamin, we examined the mechanisms by which dopamine receptor signals promote dynamin-2 recruitment and assembly at the site of Na(+),K(+)-ATPase endocytosis. Western blotting revealed that dopamine increased the association of dynamin-2 with the plasma membrane and with phosphatidylinositol 3-kinase. Dopamine inhibited Na(+),K(+)-ATPase activity in OK cells and in those overexpressing wild type dynamin-2 but not in cells expressing a dominant-negative mutant. Dephosphorylation of dynamin is important for its assembly. Dopamine increased protein phosphatase 2A activity and dephosphorylated dynamin-2. In cells expressing a dominant-negative mutant of protein phosphatase 2A, dopamine failed to dephosphorylate dynamin-2 and to reduce Na(+),K(+)-ATPase activity. Dynamin-2 is phosphorylated at Ser(848), and expression of the S848A mutant significantly blocked the inhibitory effect of dopamine. These results demonstrate a distinct signaling network originating from the dopamine receptor that regulates the state of dynamin-2 phosphorylation and that promotes its location (by interaction with phosphatidylinositol 3-kinase) at the site of Na(+),K(+)-ATPase endocytosis.
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Affiliation(s)
- Riad Efendiev
- Department of Molecular Medicine, The Rolf Luft Center for Diabetes Research, Karolinska Institutet, Karolinska Hospital, S-171 76 Stockholm, Sweden
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48
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Pierre SV, Duran MJ, Carr DL, Pressley TA. Structure/function analysis of Na(+)-K(+)-ATPase central isoform-specific region: involvement in PKC regulation. Am J Physiol Renal Physiol 2002; 283:F1066-74. [PMID: 12372782 DOI: 10.1152/ajprenal.00153.2002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Specific functions served by the various Na(+)-K(+)-ATPase alpha-isoforms are likely to originate in regions of structural divergence within their primary structures. The isoforms are nearly identical, with the exception of the NH(2) terminus and a 10-residue region near the center of each molecule (isoform-specific region; ISR). Although the NH(2) terminus has been clearly identified as a source of isoform functional diversity, other regions seem to be involved. We investigated whether the central ISR could also contribute to isoform variability. We constructed chimeric molecules in which the central ISRs of rat alpha(1)- and alpha(2)-isoforms were exchanged. After stable transfection into opossum kidney cells, the chimeras were characterized for two properties known to differ dramatically among the isoforms: their K(+) deocclusion pattern and their response to PKC activation. Comparisons with rat full-length alpha(1)- and alpha(2)-isoforms expressed under the same conditions suggest an involvement of the central ISR in the response to PKC but not in K(+) deocclusion.
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Affiliation(s)
- Sandrine V Pierre
- Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA.
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