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Vidović A, Dolinar K, Chibalin AV, Pirkmajer S. AMPK and glucose deprivation exert an isoform-specific effect on the expression of Na +,K +-ATPase subunits in cultured myotubes. J Muscle Res Cell Motil 2024; 45:139-154. [PMID: 38709429 DOI: 10.1007/s10974-024-09673-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/24/2024] [Indexed: 05/07/2024]
Abstract
In skeletal muscle, Na+,K+-ATPase (NKA), a heterodimeric (α/β) P-type ATPase, has an essential role in maintenance of Na+ and K+ homeostasis, excitability, and contractility. AMP-activated protein kinase (AMPK), an energy sensor, increases the membrane abundance and activity of NKA in L6 myotubes, but its potential role in regulation of NKA content in skeletal muscle, which determines maximum capacity for Na+ and K+ transport, has not been clearly delineated. We examined whether energy stress and/or AMPK affect expression of NKA subunits in rat L6 and primary human myotubes. Energy stress, induced by glucose deprivation, increased protein content of NKAα1 and NKAα2 in L6 myotubes, while decreasing the content of NKAα1 in human myotubes. Pharmacological AMPK activators (AICAR, A-769662, and diflunisal) modulated expression of NKA subunits, but their effects only partially mimicked those that occurred in response to glucose deprivation, indicating that AMPK does not mediate all effects of energy stress on NKA expression. Gene silencing of AMPKα1/α2 increased protein levels of NKAα1 in L6 myotubes and NKAα1 mRNA levels in human myotubes, while decreasing NKAα2 protein levels in L6 myotubes. Collectively, our results suggest a role for energy stress and AMPK in modulation of NKA expression in skeletal muscle. However, their modulatory effects were not conserved between L6 myotubes and primary human myotubes, which suggests that coupling between energy stress, AMPK, and regulation of NKA expression in vitro depends on skeletal muscle cell model.
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Affiliation(s)
- Anja Vidović
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
- National Research Tomsk State University, Tomsk, Russia
| | - Sergej Pirkmajer
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.
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2
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Arystarkhova E, Sweadner KJ. Na,K-ATPase Expression Can Be Limited Post-Transcriptionally: A Test of the Role of the Beta Subunit, and a Review of Evidence. Int J Mol Sci 2024; 25:7414. [PMID: 39000521 PMCID: PMC11242325 DOI: 10.3390/ijms25137414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/16/2024] Open
Abstract
The Na,K-ATPase is an α-β heterodimer. It is well known that the Na,K-ATPase β subunit is required for the biosynthesis and trafficking of the α subunit to the plasma membrane. During investigation of properties of human ATP1A3 mutations in 293 cells, we observed a reciprocal loss of endogenous ATP1A1 when expressing ATP1A3. Scattered reports going back as far as 1991 have shown that experimental expression of one subunit can result in reduction in another, suggesting that the total amount is strictly limited. It seems logical that either α or β subunit should be rate-limiting for assembly and functional expression. Here, we present evidence that neither α nor β may be limiting and that there is another level of control that limits the amount of Na,K-ATPase to physiological levels. We propose that α subunits compete for something specific, like a private chaperone, required to finalize their biosynthesis or to prevent their degradation in the endoplasmic reticulum.
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Affiliation(s)
- Elena Arystarkhova
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Kathleen J. Sweadner
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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3
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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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4
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Chkadua G, Nozadze E, Tsakadze L, Shioshvili L, Arutinova N, Leladze M, Dzneladze S, Javakhishvili M, Jariashvili T, Petriashvili E. The effect of cytochrome c on Na,K-ATPase. J Bioenerg Biomembr 2024; 56:221-234. [PMID: 38517564 DOI: 10.1007/s10863-024-10012-3] [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: 09/05/2023] [Accepted: 03/09/2024] [Indexed: 03/24/2024]
Abstract
Na,K-ATPase is a crucial enzyme responsible for maintaining Na+, K+-gradients across the cell membrane, which is essential for numerous physiological processes within various organs and tissues. Due to its significance in cellular physiology, inhibiting Na,K-ATPase can have profound physiological consequences. This characteristic makes it a target for various pharmacological applications, and drugs that modulate the pump's activity are thus used in the treatment of several medical conditions. Cytochrome c (Cytc) is a protein with dual functions in the cell. In the mitochondria, it is essential for ATP synthesis and energy production. However, in response to apoptotic stimuli, it is released into the cytosol, where it triggers programmed cell death through the intrinsic apoptosis pathway. Aside from its role in canonical intrinsic apoptosis, Cytc also plays additional roles. For instance, Cytc participates in certain non-apoptotic functions -those which are less well-understood in comparison to its role in apoptosis. Within this in vitro study, we have shown the impact of Cytc on Na,K-ATPase for the first time. Cytc has a biphasic action on Na,K-ATPase, with activation at low concentrations (0.06 ng/ml; 6 ng/ml) and inhibition at high concentration (120 ng/ml). Cytc moreover displays isoform/subunit specificity and regulates the Na+ form of the enzyme, while having no effect on the activity or kinetic parameters of the K+-dependent form of the enzyme. Changing the affinity of p-chloromercuribenzoic acid (PCMB) by Cytc is therefore both a required and sufficient condition for confirming that PCMB and Cytc share the same target, namely the thiol groups of cysteine in Na,K-ATPase.
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Affiliation(s)
- Gvantsa Chkadua
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia.
| | - Eka Nozadze
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
| | - Leila Tsakadze
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
| | - Lia Shioshvili
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
| | - Nana Arutinova
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
| | - Marine Leladze
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
| | - Sopio Dzneladze
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
| | - Maia Javakhishvili
- Ivane Beritashvili Center of Experimental Biomedicine, 14 Gotua Str, 0160, Tbilisi, Georgia
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Khan N, Kurnik-Łucka M, Latacz G, Gil K. Systematic-Narrative Hybrid Literature Review: Crosstalk between Gastrointestinal Renin-Angiotensin and Dopaminergic Systems in the Regulation of Intestinal Permeability by Tight Junctions. Int J Mol Sci 2024; 25:5566. [PMID: 38791603 PMCID: PMC11122119 DOI: 10.3390/ijms25105566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/12/2024] [Accepted: 05/18/2024] [Indexed: 05/26/2024] Open
Abstract
In the first part of this article, the role of intestinal epithelial tight junctions (TJs), together with gastrointestinal dopaminergic and renin-angiotensin systems, are narratively reviewed to provide sufficient background. In the second part, the current experimental data on the interplay between gastrointestinal (GI) dopaminergic and renin-angiotensin systems in the regulation of intestinal epithelial permeability are reviewed in a systematic manner using the PRISMA methodology. Experimental data confirmed the copresence of DOPA decarboxylase (DDC) and angiotensin converting enzyme 2 (ACE2) in human and rodent enterocytes. The intestinal barrier structure and integrity can be altered by angiotensin (1-7) and dopamine (DA). Both renin-angiotensin and dopaminergic systems influence intestinal Na+/K+-ATPase activity, thus maintaining electrolyte and nutritional homeostasis. The colocalization of B0AT1 and ACE2 indicates the direct role of the renin-angiotensin system in amino acid absorption. Yet, more studies are needed to thoroughly define the structural and functional interaction between TJ-associated proteins and GI renin-angiotensin and dopaminergic systems.
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Affiliation(s)
- Nadia Khan
- Faculty of Medicine, Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow, Poland
- Faculty of Pharmacy, Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, 31-008 Krakow, Poland
| | - Magdalena Kurnik-Łucka
- Faculty of Medicine, Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow, Poland
| | - Gniewomir Latacz
- Faculty of Pharmacy, Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, 31-008 Krakow, Poland
| | - Krzysztof Gil
- Faculty of Medicine, Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow, Poland
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6
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Zhang X, Lee W, Bian JS. Recent Advances in the Study of Na +/K +-ATPase in Neurodegenerative Diseases. Cells 2022; 11:cells11244075. [PMID: 36552839 PMCID: PMC9777075 DOI: 10.3390/cells11244075] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Na+/K+-ATPase (NKA), a large transmembrane protein, is expressed in the plasma membrane of most eukaryotic cells. It maintains resting membrane potential, cell volume and secondary transcellular transport of other ions and neurotransmitters. NKA consumes about half of the ATP molecules in the brain, which makes NKA highly sensitive to energy deficiency. Neurodegenerative diseases (NDDs) are a group of diseases characterized by chronic, progressive and irreversible neuronal loss in specific brain areas. The pathogenesis of NDDs is sophisticated, involving protein misfolding and aggregation, mitochondrial dysfunction and oxidative stress. The protective effect of NKA against NDDs has been emerging gradually in the past few decades. Hence, understanding the role of NKA in NDDs is critical for elucidating the underlying pathophysiology of NDDs and identifying new therapeutic targets. The present review focuses on the recent progress involving different aspects of NKA in cellular homeostasis to present in-depth understanding of this unique protein. Moreover, the essential roles of NKA in NDDs are discussed to provide a platform and bright future for the improvement of clinical research in NDDs.
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Affiliation(s)
- Xiaoyan Zhang
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Weithye Lee
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117600, Singapore
| | - Jin-Song Bian
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
- Correspondence:
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The role of AMPK in regulation of Na +,K +-ATPase in skeletal muscle: does the gauge always plug the sink? J Muscle Res Cell Motil 2021; 42:77-97. [PMID: 33398789 DOI: 10.1007/s10974-020-09594-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/14/2020] [Indexed: 12/14/2022]
Abstract
AMP-activated protein kinase (AMPK) is a cellular energy gauge and a major regulator of cellular energy homeostasis. Once activated, AMPK stimulates nutrient uptake and the ATP-producing catabolic pathways, while it suppresses the ATP-consuming anabolic pathways, thus helping to maintain the cellular energy balance under energy-deprived conditions. As much as ~ 20-25% of the whole-body ATP consumption occurs due to a reaction catalysed by Na+,K+-ATPase (NKA). Being the single most important sink of energy, NKA might seem to be an essential target of the AMPK-mediated energy saving measures, yet NKA is vital for maintenance of transmembrane Na+ and K+ gradients, water homeostasis, cellular excitability, and the Na+-coupled transport of nutrients and ions. Consistent with the model that AMPK regulates ATP consumption by NKA, activation of AMPK in the lung alveolar cells stimulates endocytosis of NKA, thus suppressing the transepithelial ion transport and the absorption of the alveolar fluid. In skeletal muscles, contractions activate NKA, which opposes a rundown of transmembrane ion gradients, as well as AMPK, which plays an important role in adaptations to exercise. Inhibition of NKA in contracting skeletal muscle accentuates perturbations in ion concentrations and accelerates development of fatigue. However, different models suggest that AMPK does not inhibit or even stimulates NKA in skeletal muscle, which appears to contradict the idea that AMPK maintains the cellular energy balance by always suppressing ATP-consuming processes. In this short review, we examine the role of AMPK in regulation of NKA in skeletal muscle and discuss the apparent paradox of AMPK-stimulated ATP consumption.
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8
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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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Engevik AC, Kaji I, Goldenring JR. The Physiology of the Gastric Parietal Cell. Physiol Rev 2020; 100:573-602. [PMID: 31670611 PMCID: PMC7327232 DOI: 10.1152/physrev.00016.2019] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 10/10/2019] [Accepted: 10/13/2019] [Indexed: 12/11/2022] Open
Abstract
Parietal cells are responsible for gastric acid secretion, which aids in the digestion of food, absorption of minerals, and control of harmful bacteria. However, a fine balance of activators and inhibitors of parietal cell-mediated acid secretion is required to ensure proper digestion of food, while preventing damage to the gastric and duodenal mucosa. As a result, parietal cell secretion is highly regulated through numerous mechanisms including the vagus nerve, gastrin, histamine, ghrelin, somatostatin, glucagon-like peptide 1, and other agonists and antagonists. The tight regulation of parietal cells ensures the proper secretion of HCl. The H+-K+-ATPase enzyme expressed in parietal cells regulates the exchange of cytoplasmic H+ for extracellular K+. The H+ secreted into the gastric lumen by the H+-K+-ATPase combines with luminal Cl- to form gastric acid, HCl. Inhibition of the H+-K+-ATPase is the most efficacious method of preventing harmful gastric acid secretion. Proton pump inhibitors and potassium competitive acid blockers are widely used therapeutically to inhibit acid secretion. Stimulated delivery of the H+-K+-ATPase to the parietal cell apical surface requires the fusion of intracellular tubulovesicles with the overlying secretory canaliculus, a process that represents the most prominent example of apical membrane recycling. In addition to their unique ability to secrete gastric acid, parietal cells also play an important role in gastric mucosal homeostasis through the secretion of multiple growth factor molecules. The gastric parietal cell therefore plays multiple roles in gastric secretion and protection as well as coordination of physiological repair.
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Affiliation(s)
- Amy C Engevik
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
| | - Izumi Kaji
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
| | - James R Goldenring
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
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10
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Nepal N, Arthur S, Sundaram U. Unique Regulation of Na-K-ATPase during Growth and Maturation of Intestinal Epithelial Cells. Cells 2019; 8:cells8060593. [PMID: 31208048 PMCID: PMC6628168 DOI: 10.3390/cells8060593] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 06/09/2019] [Accepted: 06/13/2019] [Indexed: 12/25/2022] Open
Abstract
Na-K-ATPase on the basolateral membrane provides the favorable transcellular Na gradient for the proper functioning of Na-dependent nutrient co-transporters on the brush border membrane (BBM) of enterocytes. As cells mature from crypts to villus, Na-K-ATPase activity doubles, to accommodate for the increased BBM Na-dependent nutrient absorption. However, the mechanism of increased Na-K-ATPase activity during the maturation of enterocytes is not known. Therefore, this study aimed to determine the mechanisms involved in the functional transition of Na-K-ATPase during the maturation of crypts to villus cells. Na-K-ATPase activity gradually increased as IEC-18 cells matured in vitro from day 0 (crypts) through day 4 (villus) of post-confluence. mRNA abundance and Western blot studies showed no change in the levels of Na-K-ATPase subunits α1 and β1 from 0 to 4 days post-confluent cells. However, Na-K-ATPase α1 phosphorylation levels on serine and tyrosine, but not threonine, residues gradually increased. These data indicate that as enterocytes mature from crypt-like to villus-like in culture, the functional activity of Na-K-ATPase increases secondary to altered affinity of the α1 subunit to extracellular K+, in order to accommodate the functional preference of the intestinal cell type. This altered affinity is likely due to increased phosphorylation of the α1 subunit, specifically at serine and tyrosine residues.
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Affiliation(s)
- Niraj Nepal
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA.
| | - Subha Arthur
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA.
| | - Uma Sundaram
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA.
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11
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Differential expression patterns of sodium potassium ATPase alpha and beta subunit isoforms in mouse brain during postnatal development. Neurochem Int 2019; 128:163-174. [PMID: 31009649 DOI: 10.1016/j.neuint.2019.04.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 04/05/2019] [Accepted: 04/15/2019] [Indexed: 11/21/2022]
Abstract
The sodium potassium ATPase (Na+/K+ ATPase) is essential for the maintenance of a low intracellular Na+ and a high intracellular K+ concentration. Loss of function of the Na+/K+ ATPase due to mutations in Na+/K+ ATPase genes, anoxic conditions, depletion of ATP or inhibition of the Na+/K+ ATPase function using cardiac glycosides such as digitalis, causes a depolarization of the resting membrane potential. While in non-excitable cells, the uptake of glucose and amino acids is decreased if the function of the Na+/K+ ATPase is compromised, in excitable cells the symptoms range from local hyper-excitability to inactivating depolarization. Although several studies have demonstrated the differential expression of the various Na+/K+ ATPase alpha and beta isoforms in the brain tissue of rodents, their expression profile during development has yet to be thoroughly investigated. An immunohistochemical analysis of postnatal day 19 mouse brain showed ubiquitous expression of Na+/K+ ATPase isoforms α1, β1 and β2 in both neurons and glial cells, whereas α2 was expressed mostly in glial cells and the α3 and β3 isoforms were expressed in neurons. Furthermore, we examined potential changes in the relative expression of the different Na+/K+ ATPase isoforms in different brain areas of postnatal day 6 and in adult 9 months old animals using immunoblot analysis. Our results show a significant up-regulation of the α1 isoform in cortex, hippocampus and cerebellum, whereas, the α2 isoform was significantly up-regulated in midbrain. The β3 isoform showed a significant up-regulation in all brain areas investigated. The up-regulation of the α3 isoform matched that of the β2 isoform which were both significantly up-regulated in cortex, hippocampus and midbrain, suggesting that the increased maturation of the neuronal network is accompanied by an increase in expression of α3/β2 complexes in these brain structures.
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12
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Hormonal regulation of Na +-K +-ATPase from the evolutionary perspective. CURRENT TOPICS IN MEMBRANES 2019; 83:315-351. [PMID: 31196608 DOI: 10.1016/bs.ctm.2019.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Na+-K+-ATPase, an α/β heterodimer, is an ancient enzyme that maintains Na+ and K+ gradients, thus preserving cellular ion homeostasis. In multicellular organisms, this basic housekeeping function is integrated to fulfill the needs of specialized organs and preserve whole-body homeostasis. In vertebrates, Na+-K+-ATPase is essential for many fundamental physiological processes, such as nerve conduction, muscle contraction, nutrient absorption, and urine excretion. During vertebrate evolution, three key developments contributed to diversification and integration of Na+-K+-ATPase functions. Generation of novel α- and β-subunits led to formation of multiple Na+-K+-ATPase isoenyzmes with distinct functional characteristics. Development of a complex endocrine system enabled efficient coordination of diverse Na+-K+-ATPase functions. Emergence of FXYDs, small transmembrane proteins that regulate Na+-K+-ATPase, opened new ways to modulate its function. FXYDs are a vertebrate innovation and an important site of hormonal action, suggesting they played an especially prominent role in evolving interaction between Na+-K+-ATPase and the endocrine system in vertebrates.
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Bernhem K, Blom H, Brismar H. Quantification of endogenous and exogenous protein expressions of Na,K-ATPase with super-resolution PALM/STORM imaging. PLoS One 2018; 13:e0195825. [PMID: 29694368 PMCID: PMC5918999 DOI: 10.1371/journal.pone.0195825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 03/30/2018] [Indexed: 01/19/2023] Open
Abstract
Transient transfection of fluorescent fusion proteins is a key enabling technology in fluorescent microscopy to spatio-temporally map cellular protein distributions. Transient transfection of proteins may however bypass normal regulation of expression, leading to overexpression artefacts like misallocations and excess amounts. In this study we investigate the use of STORM and PALM microscopy to quantitatively monitor endogenous and exogenous protein expression. Through incorporation of an N-terminal hemagglutinin epitope to a mMaple3 fused Na,K-ATPase (α1 isoform), we analyze the spatial and quantitative changes of plasma membrane Na,K-ATPase localization during competitive transient expression. Quantification of plasma membrane protein density revealed a time dependent increase of Na,K-ATPase, but no increase in size of protein clusters. Results show that after 41h transfection, the total plasma membrane density of Na,K-ATPase increased by 63% while the endogenous contribution was reduced by 16%.
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Affiliation(s)
- Kristoffer Bernhem
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Hans Blom
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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14
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Khajah MA, Mathew PM, Luqmani YA. Na+/K+ ATPase activity promotes invasion of endocrine resistant breast cancer cells. PLoS One 2018; 13:e0193779. [PMID: 29590154 PMCID: PMC5874017 DOI: 10.1371/journal.pone.0193779] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/17/2018] [Indexed: 01/27/2023] Open
Abstract
Background The Na+/K+-ATPase (NKP) is an important ion transporter also involved in signal transduction. Its expression profile is altered in various tumours including that of the breast. We studied the effect of inhibiting NKP activity in non-tumorigenic breast cell line and in estrogen receptor positive and negative breast cancer cells. Methods Expression and localization of NKP and downstream signaling molecules were determined by RT-PCR, western blotting and immunofluorescence. Cell proliferation, apoptosis and cell cycle stage were determined using MTT, annexin V and flow cytometry. Cell motility and invasion were determined using wound healing and matrigel assays. Total matrix metalloproteinase (MMP) was determined by a fluorescence-based assay. Results NKP was mainly localized on the cell membrane. Its baseline expression and activity were enhanced in breast cancer compared to the non-tumorigenic breast cell line. Ouabain and 3,4,5,6-tetrahydroxyxanthone (TTX) treatment significantly inhibited NKP activity, which significantly reduced cell proliferation, motility, invasion and pH-induced membrane blebbing. EGF stimulation induced internalization of NKP from the cell membrane to the cytoplasm. Ouabain inhibited EGF-induced phosphorylation of Rac/cdc42, profillin, ERK1/2 and P70S6K. Conclusions The NKP may offer a novel therapeutic target in breast cancer patients who have developed metastasis, aiming to improve therapeutic outcomes and enhance survival rate.
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15
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Colquhoun RJ, Magrini MA, Haun CT, Muddle TWD, Tomko PM, Luera MJ, Mackey CS, Vann CG, Martin JS, Young KC, DeFreitas JM, Roberts MD, Jenkins NDM. Muscle phenotype is related to motor unit behavior of the vastus lateralis during maximal isometric contractions. Physiol Rep 2018. [PMID: 29527830 PMCID: PMC5845862 DOI: 10.14814/phy2.13636] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous investigations have reported a relationship between skeletal muscle phenotype and motor unit (MU) firing parameters during submaximal contractions. The purpose of the current investigation, however, was to examine the relationships between motor unit firing behavior during a maximal voluntary contraction, Myosin Heavy Chain (MHC) isoform content, and various molecular neuromuscular targets of the vastus lateralis (VL) muscle in resistance-trained men. Ten resistance-trained males completed a trapezoidal ramp contraction up to 100% of their maximal voluntary isometric strength (MVIC). Surface electromyography was recorded from the VL using a multichannel electrode array and decomposed to examine the firing characteristics of individual MUs. A skeletal muscle biopsy of the VL was also collected from each subject. Regression analyses were performed to identify relationships between type II fiber area and the slopes and/or intercepts of the mean firing rate (FRMEAN ) versus recruitment threshold (RT), max firing rate (FRMAX ) versus RT, and RT versus MU action potential amplitude (MUAPPP ) relationships. There were significant inverse relationships between type II fiber area and the y-intercept of the FR versus RT relationship (P < 0.05). Additionally, strong relationships (r > 0.5) were found between type II fiber area and FRMEAN versus RT slope and RT versus MUAPPP slope and intercept. These data further support the hypothesis that skeletal muscle phenotype is related to MU behavior during isometric contraction. However, our data, in concert with previous investigations, may suggest that these relationships are influenced by the intensity of the contraction.
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Affiliation(s)
- Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Mitchel A Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Cody T Haun
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Tyler W D Muddle
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Patrick M Tomko
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Micheal J Luera
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Cameron S Mackey
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Christopher G Vann
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Jeffrey S Martin
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Kaelin C Young
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Michael D Roberts
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Nathaniel D M Jenkins
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
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16
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Repositioning of Somatic Golgi Apparatus Is Essential for the Dendritic Establishment of Adult-Born Hippocampal Neurons. J Neurosci 2017; 38:631-647. [PMID: 29217690 DOI: 10.1523/jneurosci.1217-17.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 10/02/2017] [Accepted: 10/29/2017] [Indexed: 01/22/2023] Open
Abstract
New dentate granule cells (DGCs) are continuously generated, and integrate into the preexisting hippocampal network in the adult brain. How an adult-born neuron with initially simple spindle-like morphology develops into a DGC, consisting of a single apical dendrite with further branches, remains largely unknown. Here, using retroviruses to birth date and manipulate newborn neurons, we examined initial dendritic formation and possible underlying mechanisms. We found that GFP-expressing newborn cells began to establish a DGC-like morphology at ∼7 d after birth, with a primary dendrite pointing to the molecular layer, but at this stage, with several neurites in the neurogenic zone. Interestingly, the Golgi apparatus, an essential organelle for neurite growth and maintenance, was dynamically repositioning in the soma of newborn cells during this initial integration stage. Two weeks after birth, by which time most neurites in the neurogenic zone were eliminated, a compact Golgi apparatus was positioned exclusively at the base of the primary dendrite. We analyzed the presence of Golgi-associated genes using single-cell transcriptomes of newborn DGCs, and among Golgi-related genes, found the presence of STK25 and STRAD, regulators of embryonic neuronal development. When we knocked down either of these two proteins, we found Golgi mislocalization and extensive aberrant dendrite formation. Furthermore, overexpression of a mutated form of STRAD, underlying the disorder polyhydramnios, megalencephaly, and symptomatic epilepsy, characterized by abnormal brain development and intractable epilepsy, caused similar defects in Golgi localization and dendrite formation in adult-born neurons. Together, our findings reveal a role for Golgi repositioning in regulating the initial integration of adult-born DGCs.SIGNIFICANCE STATEMENT Since the discovery of the continuous generation of new neurons in the adult hippocampus, extensive effort was directed toward understanding the functional contribution of these newborn neurons to the existing hippocampal circuit and associated behaviors, while the molecular mechanisms controlling their early morphological integration are less well understood. Dentate granule cells (DGCs) have a single, complex, apical dendrite. The events leading adult-born DGCs' to transition from simple spindle-like morphology to mature dendrite morphology are largely unknown. We studied establishment of newborn DGCs dendritic pattern and found it was mediated by a signaling pathway regulating precise localization of the Golgi apparatus. Furthermore, this Golgi-associated mechanism for dendrite establishment might be impaired in a human genetic epilepsy syndrome, polyhydramnios, megalencephaly, and symptomatic epilepsy.
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Li L, Feng R, Xu Q, Zhang F, Liu T, Cao J, Fei S. Expression of the β3 subunit of Na +/K +-ATPase is increased in gastric cancer and regulates gastric cancer cell progression and prognosis via the PI3/AKT pathway. Oncotarget 2017; 8:84285-84299. [PMID: 29137423 PMCID: PMC5663595 DOI: 10.18632/oncotarget.20894] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 08/26/2017] [Indexed: 12/13/2022] Open
Abstract
ATP1B3 encodes the β3 subunit of Na+/K+-ATPase and is located in the q22-23 region of chromosome 3. Na+/K+-ATPase participates in normal cellular activities but also plays a crucial role in carcinogenesis. In the present study, we found that expression of the β3 subunit of Na+/K+-ATPase was increased in human gastric cancer tissues compared with that in normal matched tissues and that this increased expression predicted a poor outcome. ATP1B3 expression was elevated at both the mRNA and protein levels in gastric cancer cell lines relative to those in a normal gastric epithelial cell line. Interestingly, ATP1B3 knockdown significantly inhibited cell proliferation, colony-formation ability, migration, and invasion and increased apoptosis in human gastric carcinoma cell lines. Additionally, knockdown induced cell cycle arrest at the G2/M phase. Furthermore, we demonstrated that ATP1B3 silencing decreased the expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and phosphorylated AKT (p-AKT), indicating that ATP1B3 regulates gastric cancer cell progression via the PI3K/AKT signalling pathway. Hence, the β3 subunit of Na+/K+-ATPase plays an essential role in the tumourigenesis of gastric cancer and may be a potential prognostic and therapeutic target for the treatment of gastric cancer.
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Affiliation(s)
- Li Li
- Department of Gastroenterology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
| | - Ru Feng
- Department of Gastroenterology, Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
| | - Qian Xu
- Department of Gastroenterology, Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
| | - Feiyue Zhang
- Department of Gastroenterology, Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
| | - Tong Liu
- Department of Gastroenterology, Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
| | - Jiang Cao
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
| | - Sujuan Fei
- Department of Gastroenterology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, P.R. China
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On the Many Actions of Ouabain: Pro-Cystogenic Effects in Autosomal Dominant Polycystic Kidney Disease. Molecules 2017; 22:molecules22050729. [PMID: 28467389 PMCID: PMC5688955 DOI: 10.3390/molecules22050729] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 04/19/2017] [Accepted: 04/30/2017] [Indexed: 02/07/2023] Open
Abstract
Ouabain and other cardenolides are steroidal compounds originally discovered in plants. Cardenolides were first used as poisons, but after finding their beneficial cardiotonic effects, they were rapidly included in the medical pharmacopeia. The use of cardenolides to treat congestive heart failure remained empirical for centuries and only relatively recently, their mechanisms of action became better understood. A breakthrough came with the discovery that ouabain and other cardenolides exist as endogenous compounds that circulate in the bloodstream of mammals. This elevated these compounds to the category of hormones and opened new lines of investigation directed to further study their biological role. Another important discovery was the finding that the effect of ouabain was mediated not only by inhibition of the activity of the Na,K-ATPase (NKA), but by the unexpected role of NKA as a receptor and a signal transducer, which activates a complex cascade of intracellular second messengers in the cell. This broadened the interest for ouabain and showed that it exerts actions that go beyond its cardiotonic effect. It is now clear that ouabain regulates multiple cell functions, including cell proliferation and hypertrophy, apoptosis, cell adhesion, cell migration, and cell metabolism in a cell and tissue type specific manner. This review article focuses on the cardenolide ouabain and discusses its various in vitro and in vivo effects, its role as an endogenous compound, its mechanisms of action, and its potential use as a therapeutic agent; placing especial emphasis on our findings of ouabain as a pro-cystogenic agent in autosomal dominant polycystic kidney disease (ADPKD).
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La J, Reed E, Chan L, Smolyaninova LV, Akomova OA, Mutlu GM, Orlov SN, Dulin NO. Downregulation of TGF-β Receptor-2 Expression and Signaling through Inhibition of Na/K-ATPase. PLoS One 2016; 11:e0168363. [PMID: 28006004 PMCID: PMC5179089 DOI: 10.1371/journal.pone.0168363] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 11/30/2016] [Indexed: 01/06/2023] Open
Abstract
Transforming growth factor-beta (TGF-β) is a multi-functional cytokine implicated in the control of cell growth and differentiation. TGF-β signals through a complex of TGF-β receptors 1 and 2 (TGFβR1 and TGFβR2) that phosphorylate and activate Smad2/3 transcription factors driving transcription of the Smad-target genes. The Na+/K+-ATPase is an integral plasma membrane protein critical for maintaining the electro-chemical gradient of Na+ and K+ in the cell. We found that inhibition of the Na+/K+ ATPase by ouabain results in a dramatic decrease in the expression of TGFβR2 in human lung fibrobalsts (HLF) at the mRNA and protein levels. This was accompanied by inhibition of TGF-β-induced Smad phosphorylation and the expression of TGF-β target genes, such as fibronectin and smooth muscle alpha-actin. Inhibition of Na+/K+ ATPase by an alternative approach (removal of extracellular potassium) had a similar effect in HLF. Finally, treatment of lung alveolar epithelial cells (A549) with ouabain also resulted in the downregulation of TGFβR2, the inhibition of TGF-β-induced Smad phosphorylation and of the expression of mesenchymal markers, vimentin and fibronectin. Together, these data demonstrate a critical role of Na+/K+-ATPase in the control of TGFβR2 expression, TGF-β signaling and cell responses to TGF-β.
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Affiliation(s)
- Jennifer La
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, the University of Chicago, Chicago, IL, United States of America
| | - Eleanor Reed
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, the University of Chicago, Chicago, IL, United States of America
| | - Lan Chan
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, the University of Chicago, Chicago, IL, United States of America
| | - Larisa V. Smolyaninova
- Laboratory of Biomembranes, Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Olga A. Akomova
- Laboratory of Biomembranes, Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Gökhan M. Mutlu
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, the University of Chicago, Chicago, IL, United States of America
| | - Sergei N. Orlov
- Laboratory of Biomembranes, Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
- Siberian Medical State University, Tomsk, Russia
| | - Nickolai O. Dulin
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, the University of Chicago, Chicago, IL, United States of America
- Siberian Medical State University, Tomsk, Russia
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20
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Lobato-Álvarez JA, Roldán ML, López-Murillo TDC, González-Ramírez R, Bonilla-Delgado J, Shoshani L. The Apical Localization of Na +, K +-ATPase in Cultured Human Retinal Pigment Epithelial Cells Depends on Expression of the β 2 Subunit. Front Physiol 2016; 7:450. [PMID: 27774068 PMCID: PMC5054689 DOI: 10.3389/fphys.2016.00450] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 09/20/2016] [Indexed: 11/28/2022] Open
Abstract
Na+, K+-ATPase, or the Na+ pump, is a key component in the maintenance of the epithelial phenotype. In most epithelia, the pump is located in the basolateral domain. Studies from our laboratory have shown that the β1 subunit of Na+, K+-ATPase plays an important role in this mechanism because homotypic β1-β1 interactions between neighboring cells stabilize the pump in the lateral membrane. However, in the retinal pigment epithelium (RPE), the Na+ pump is located in the apical domain. The mechanism of polarization in this epithelium is unclear. We hypothesized that the apical polarization of the pump in RPE cells depends on the expression of its β2 subunit. ARPE-19 cells cultured for up to 8 weeks on inserts did not polarize, and Na+, K+-ATPase was expressed in the basolateral membrane. In the presence of insulin, transferrin and selenic acid (ITS), ARPE-19 cells cultured for 4 weeks acquired an RPE phenotype, and the Na+ pump was visible in the apical domain. Under these conditions, Western blot analysis was employed to detect the β2 isoform and immunofluorescence analysis revealed an apparent apical distribution of the β2 subunit. qPCR results showed a time-dependent increase in the level of β2 isoform mRNA, suggesting regulation at the transcriptional level. Moreover, silencing the expression of the β2 isoform in ARPE-19 cells resulted in a decrease in the apical localization of the pump, as assessed by the mislocalization of the α2 subunit in that domain. Our results demonstrate that the apical polarization of Na+, K+-ATPase in RPE cells depends on the expression of the β2 subunit.
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Affiliation(s)
- Jorge A Lobato-Álvarez
- Laboratory of Epithelial Research, Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN México City, Mexico
| | - María L Roldán
- Laboratory of Epithelial Research, Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN México City, Mexico
| | - Teresa Del Carmen López-Murillo
- Laboratory of Epithelial Research, Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN México City, Mexico
| | - Ricardo González-Ramírez
- Department of Molecular Biology and Histocompatibility, Hospital General Dr. Manuel Gea González México City, Mexico
| | - José Bonilla-Delgado
- Research Unit, Laboratory of Genetics and Molecular Diagnosis, Hospital Juárez de México México City, Mexico
| | - Liora Shoshani
- Laboratory of Epithelial Research, Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN México City, Mexico
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Pirkmajer S, Chibalin AV. Na,K-ATPase regulation in skeletal muscle. Am J Physiol Endocrinol Metab 2016; 311:E1-E31. [PMID: 27166285 DOI: 10.1152/ajpendo.00539.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
Skeletal muscle contains one of the largest and the most dynamic pools of Na,K-ATPase (NKA) in the body. Under resting conditions, NKA in skeletal muscle operates at only a fraction of maximal pumping capacity, but it can be markedly activated when demands for ion transport increase, such as during exercise or following food intake. Given the size, capacity, and dynamic range of the NKA pool in skeletal muscle, its tight regulation is essential to maintain whole body homeostasis as well as muscle function. To reconcile functional needs of systemic homeostasis with those of skeletal muscle, NKA is regulated in a coordinated manner by extrinsic stimuli, such as hormones and nerve-derived factors, as well as by local stimuli arising in skeletal muscle fibers, such as contractions and muscle energy status. These stimuli regulate NKA acutely by controlling its enzymatic activity and/or its distribution between the plasma membrane and the intracellular storage compartment. They also regulate NKA chronically by controlling NKA gene expression, thus determining total NKA content in skeletal muscle and its maximal pumping capacity. This review focuses on molecular mechanisms that underlie regulation of NKA in skeletal muscle by major extrinsic and local stimuli. Special emphasis is given to stimuli and mechanisms linking regulation of NKA and energy metabolism in skeletal muscle, such as insulin and the energy-sensing AMP-activated protein kinase. Finally, the recently uncovered roles for glutathionylation, nitric oxide, and extracellular K(+) in the regulation of NKA in skeletal muscle are highlighted.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; and
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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22
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Laird JG, Pan Y, Modestou M, Yamaguchi DM, Song H, Sokolov M, Baker SA. Identification of a VxP Targeting Signal in the Flagellar Na+ /K+ -ATPase. Traffic 2015; 16:1239-53. [PMID: 26373354 DOI: 10.1111/tra.12332] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 09/11/2015] [Accepted: 09/11/2015] [Indexed: 12/15/2022]
Abstract
Na(+) /K(+) -ATPase (NKA) participates in setting electrochemical gradients, cardiotonic steroid signaling and cellular adhesion. Distinct isoforms of NKA are found in different tissues and subcellular localization patterns. For example, NKA α1 is widely expressed, NKA α3 is enriched in neurons and NKA α4 is a testes-specific isoform found in sperm flagella. In some tissues, ankyrin, a key component of the membrane cytoskeleton, can regulate the trafficking of NKA. In the retina, NKA and ankyrin-B are expressed in multiple cell types and immunostaining for each is striking in the synaptic layers. Labeling for NKA is also prominent along the inner segment plasma membrane (ISPM) of photoreceptors. NKA co-immunoprecipitates with ankyrin-B, but on a subcellular level colocalization of these two proteins varies dependent on the cell type. We used transgenic Xenopus laevis tadpoles to evaluate the subcellular trafficking of NKA in photoreceptors. GFP-NKA α3 and α1 are localized to the ISPM, but α4 is localized to outer segments (OSs). We identified a VxP motif responsible for the OS targeting by using a series of chimeric and mutant NKA constructs. This motif is similar to previously identified ciliary targeting motifs. Given the structural similarities between OSs and flagella, our findings shed light on the subcellular targeting of this testes-specific NKA isoform.
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Affiliation(s)
- Joseph G Laird
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Yuan Pan
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.,Current address: Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Modestos Modestou
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - David M Yamaguchi
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Hongman Song
- Department of Ophthalmology, West Virginia University School of Medicine and West Virginia University Eye Institute, Morgantown, WV, 26506, USA.,Current address: Section for Translational Research in Retina & Macular Degeneration, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, 20892, USA
| | - Maxim Sokolov
- Department of Ophthalmology, West Virginia University School of Medicine and West Virginia University Eye Institute, Morgantown, WV, 26506, USA
| | - Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
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Abstract
Pulmonary edema clearance is necessary for patients with lung injury to recover and survive. The mechanisms regulating edema clearance from the lungs are distinct from the factors contributing edema formation during injury. Edema clearance is effected via vectorial transport of Na(+) out of the airspaces which generates an osmotic gradient causing water to follow the gradient out of the cells. This Na(+) transport across the alveolar epithelium is mostly effected via apical Na(+) and chloride channels and basolateral Na,K-ATPase. The Na,K-ATPase pumps Na(+) out of the cell and K(+) into the cell against their respective gradients in an ATP-consuming reaction. Two mechanisms contribute to the regulation of the Na,K-ATPase activity:recruitment of its subunits from intracellular compartments into the basolateral membrane, and transcriptional/translational regulation. Na,K-ATPase activity and edema clearance are increased by catecholamines, aldosterone, vasopressin, overexpression of the pump genes, and others. During lung injury, mechanisms regulating edema clearance are inhibited by yet unclear pathways. Better understanding of the mechanisms that regulate pulmonary edema clearance may lead to therapeutic interventions that counterbalance the inhibition of edema clearance during lung injury and improve the lungs' ability to clear fluid, which is crucial for patient survival.
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Affiliation(s)
- Zaher S. Azzam
- Internal Medicine “B”, Rambam Health Care Campus, Department of Physiology and Biophysics, The Rappaport Family Faculty of Medicine and Research Institute, Technion, Israel Institute of Technology, Haifa, Israel
| | - Jacob I. Sznajder
- Division of Pulmonary and Critical Care Medicine, Northwestern University, Chicago, IL, USA
- To whom correspondence should be addressed. E-mail:
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Balasubramaniam SL, Gopalakrishnapillai A, Barwe SP. Ion dependence of Na-K-ATPase-mediated epithelial cell adhesion and migration. Am J Physiol Cell Physiol 2015; 309:C437-41. [PMID: 26157008 DOI: 10.1152/ajpcell.00140.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Sona Lakshme Balasubramaniam
- Nemours Center for Childhood Cancer Research, Alfred I. duPont Hospital for Children, Wilmington, Delaware; and Department of Biological Sciences, University of Delaware, Newark, Delaware
| | | | - Sonali P Barwe
- Nemours Center for Childhood Cancer Research, Alfred I. duPont Hospital for Children, Wilmington, Delaware; and Department of Biological Sciences, University of Delaware, Newark, Delaware
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25
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Scherzer P, Gal-Moscovici A, Sheikh-Hamad D, Popovtzer MM. Sodium-pump gene-expression, protein abundance and enzyme activity in isolated nephron segments of the aging rat kidney. Physiol Rep 2015; 3:3/6/e12369. [PMID: 26056060 PMCID: PMC4510615 DOI: 10.14814/phy2.12369] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Aging is associated with alteration in renal tubular functions, including sodium handling and concentrating ability. Na-K-ATPase plays a key role in driving tubular transport, and we hypothesized that decreased concentrating ability of the aging kidney is due in part to downregulation of Na-K-ATPase. In this study, we evaluated Na and K balance, aldosterone levels, and Na-K-ATPase gene expression, protein abundance, and activity in aging rat kidney. Na-K-ATPase activity (assayed microfluorometrically), mRNA (RT-PCR), and protein abundance (immunoblotting) were quantitated in the following isolated nephron segments: PCT, PST, MTAL, DCT, and CCD from 2, 8, 15, and 24 month-old-rats. In the course of aging, creatinine clearance decreased from 0.48 ± 0.02 mL/min/100 g BW to 0.28 ± 0.06 (P < 0.001) and aldosterone decreased from 23.6 ± 0.8 ng/dL to 13.2 ± 0.6 (P < 0.001). Serum Na+ and K+ increased by 4.0% and 22.5%, respectively. Na-K-ATPase activity, mRNA, and protein abundance of the α1 subunit displayed similar trends in all assayed segments; increasing in PCT and PST; decreasing in MTAL and DCT; increasing in CCD: in PCT they increased by 40%, 75%, and 250%, respectively; while in PST they increased by 80%, 50%, and 100%, respectively (P < 0.001). In MTAL they declined by 36%, 24%, and 34%, respectively, and in DCT by 38%, 59%, and 60%, respectively (P < 0.001). They were higher in CCD by 110%, 115%, and 246%, respectively (P < 0.001). Rats maintained Na/K balance; however with a steady state elevated serum K+. These results reveal quantitative changes in axial distribution of Na-K-ATPase at the level of gene expression, protein abundance, and activity in the nephrons of aging animals and may explain, in part, the pathophysiology of the senescent kidney.
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Affiliation(s)
- Pnina Scherzer
- Nephrology and Hypertension Services, Hadassah University Hospital, Jerusalem, Israel
| | - Anca Gal-Moscovici
- Nephrology and Hypertension Services, Hadassah University Hospital, Jerusalem, Israel
| | - David Sheikh-Hamad
- Nephrology and Hypertension Services, Hadassah University Hospital, Jerusalem, Israel Nephrology Division, Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Mordecai M Popovtzer
- Nephrology and Hypertension Services, Hadassah University Hospital, Jerusalem, Israel South Arizona VA Health Care System and University of Arizona, Tucson, Arizona
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Doğanli C, Oxvig C, Lykke-Hartmann K. Zebrafish as a novel model to assess Na+/K(+)-ATPase-related neurological disorders. Neurosci Biobehav Rev 2013; 37:2774-87. [PMID: 24091024 DOI: 10.1016/j.neubiorev.2013.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/08/2013] [Accepted: 09/23/2013] [Indexed: 11/26/2022]
Abstract
Modeling neurological disorders using zebrafish increases rapidly as this model system allows easy access to all developmental stages and imaging of pathological processes. A surprising degree of functional conservation has been demonstrated between human genes implicated in neurodegenerative diseases and their zebrafish orthologues. Zebrafish offers rapid high throughput screening of therapeutic compounds and live imaging of pathogenic mechanisms in vivo. Several recent zebrafish studies functionally assessed the role of the sodium-potassium pump (Na(+)/K(+)-ATPase). The Na(+)/K(+)-ATPase maintains the electrochemical gradients across the plasma membrane, essential for e.g. signaling, secondary active transport, glutamate re-uptake and neuron excitability in animal cells. Na(+)/K(+)-ATPase mutations are associated with neurological disorders, where mutations in the Na(+)/K(+)-ATPase α2 and α3 isoforms cause Familial hemiplegic migraine type 2 (FHM2) and Rapid-onset dystonia-parkinsonism (RDP)/Alternating hemiplegic childhood (AHC), respectively. In zebrafish, knock-down of Na(+)/K(+)-ATPase isoforms included skeletal and heart muscle defects, impaired embryonic motility, depolarized Rohon-beard neurons and abrupt brain ventricle development. In this review, we discuss zebrafish as a model to assess Na(+)/K(+)-ATPase isoform functions. Furthermore, studies investigating proteomic changes in both α2- and α3-isoform deficient embryos and their potential connections to the Na(+)/K(+)-ATPase functions will be discussed.
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Affiliation(s)
- Canan Doğanli
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Copenhagen, Denmark; Aarhus University, Department of Biomedicine, Ole Worms Allé 3, Building 1171, DK-8000 Aarhus, Denmark; Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10, Building 3135, DK-8000 Aarhus, Denmark
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27
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Mony S, Lee SJ, Harper JF, Barwe SP, Langhans SA. Regulation of Na,K-ATPase β1-subunit in TGF-β2-mediated epithelial-to-mesenchymal transition in human retinal pigmented epithelial cells. Exp Eye Res 2013; 115:113-22. [PMID: 23810808 DOI: 10.1016/j.exer.2013.06.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 04/15/2013] [Accepted: 06/07/2013] [Indexed: 12/14/2022]
Abstract
Proliferative vitreo retinopathy (PVR) is associated with extracellular matrix membrane (ECM) formation on the neural retina and disruption of the multilayered retinal architecture leading to distorted vision and blindness. During disease progression in PVR, retinal pigmented epithelial cells (RPE) lose cell-cell adhesion, undergo epithelial-to-mesenchymal transition (EMT), and deposit ECM leading to tissue fibrosis. The EMT process is mediated via exposure to vitreous cytokines and growth factors such as TGF-β2. Previous studies have shown that Na,K-ATPase is required for maintaining a normal polarized epithelial phenotype and that decreased Na,K-ATPase function and subunit levels are associated with TGF-β1-mediated EMT in kidney cells. In contrast to the basolateral localization of Na,K-ATPase in most epithelia, including kidney, Na,K-ATPase is found on the apical membrane in RPE cells. We now show that EMT is also associated with altered Na,K-ATPase expression in RPE cells. TGF-β2 treatment of ARPE-19 cells resulted in a time-dependent decrease in Na,K-ATPase β1 mRNA and protein levels while Na,K-ATPase α1 levels, Na,K-ATPase activity, and intracellular sodium levels remained largely unchanged. In TGF-β2-treated cells reduced Na,K-ATPase β1 mRNA inversely correlated with HIF-1α levels and analysis of the Na,K-ATPase β1 promoter revealed a putative hypoxia response element (HRE). HIF-1α bound to the Na,K-ATPase β1 promoter and inhibiting the activity of HIF-1α blocked the TGF-β2 mediated Na,K-ATPase β1 decrease suggesting that HIF-1α plays a potential role in Na,K-ATPase β1 regulation during EMT in RPE cells. Furthermore, knockdown of Na,K-ATPase β1 in ARPE-19 cells was associated with a change in cell morphology from epithelial to mesenchymal and induction of EMT markers such as α-smooth muscle actin and fibronectin, suggesting that loss of Na,K-ATPase β1 is a potential contributor to TGF-β2-mediated EMT in RPE cells.
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Affiliation(s)
- Sridevi Mony
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Rockland Center I, 1701 Rockland Road, Wilmington, DE 19803, USA.
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Irles P, Silva-Torres FA, Piulachs MD. RNAi reveals the key role of Nervana 1 in cockroach oogenesis and embryo development. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:178-188. [PMID: 23262289 DOI: 10.1016/j.ibmb.2012.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/07/2012] [Accepted: 12/11/2012] [Indexed: 06/01/2023]
Abstract
Na(+), K(+)-ATPases is a heterodimer protein consisting of α- and β-subunits that control the ion transport through cell membranes. In insects the β-subunit of the Na(+), K(+)-ATPase, known as Nervana, was characterized as a nervous system-specific glycoprotein antigen from adult Drosophila melanogaster heads. Nervana is expressed ubiquitously in all insect tissues, and in epithelial cells appeared located in a basolateral position as part of the septate junctions. Herein we study two Nervana isoforms from Blattella germanica, a cockroach species with panoistic ovaries. The sequencing and the phylogenetic analysis results suggest that these two isoforms are orthologs of D. melanogaster Nervana 1 and Nervana 2, respectively. Nervana 1 is highly expressed in the ovary of B. germanica, and depleting its expression results in changes in oocyte shape that do not impair oviposition. However, the resulting embryos show different defects and never hatch. These findings highlight the importance of this type of membrane pump in insect oogenesis as well as in embryo development, and its possible regulation by juvenile hormone.
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Affiliation(s)
- Paula Irles
- Institut de Biologia Evolutiva (Universitat Pompeu Fabra-CSIC), Passeig Marítim de la Barceloneta, 37, 08003 Barcelona, Spain.
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Caldwell KA, Shu Y, Roberts NB, Caldwell GA, O’Donnell JM. Invertebrate models of dystonia. Curr Neuropharmacol 2013; 11:16-29. [PMID: 23814534 PMCID: PMC3580786 DOI: 10.2174/157015913804999504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 06/02/2012] [Accepted: 07/03/2012] [Indexed: 01/15/2023] Open
Abstract
The neurological movement disorder dystonia is an umbrella term for a heterogeneous group of related conditions where at least 20 monogenic forms have been identified. Despite the substantial advances resulting from the identification of these loci, the function of many DYT gene products remains unclear. Comparative genomics using simple animal models to examine the evolutionarily conserved functional relationships with monogenic dystonias represents a rapid route toward a comprehensive understanding of these movement disorders. Current studies using the invertebrate animal models Caenorhabditis elegans and Drosophila melanogaster are uncovering cellular functions and mechanisms associated with mutant forms of the well-conserved gene products corresponding to DYT1, DYT5a, DYT5b, and DYT12 dystonias. Here we review recent findings from the invertebrate literature pertaining to molecular mechanisms of these gene products, torsinA, GTP cyclohydrolase I, tyrosine hydroxylase, and the alpha subunit of Na+/K ATPase, respectively. In each study, the application of powerful genetic tools developed over decades of intensive work with both of these invertebrate systems has led to mechanistic insights into these human disorders. These models are particularly amenable to large-scale genetic screens for modifiers or additional alleles, which are bolstering our understanding of the molecular functions associated with these gene products. Moreover, the use of invertebrate models for the evaluation of DYT genetic loci and their genetic interaction networks has predictive value and can provide a path forward for therapeutic intervention.
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Affiliation(s)
- Kim A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
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Reinhard L, Tidow H, Clausen MJ, Nissen P. Na(+),K (+)-ATPase as a docking station: protein-protein complexes of the Na(+),K (+)-ATPase. Cell Mol Life Sci 2013; 70:205-22. [PMID: 22695678 PMCID: PMC11113973 DOI: 10.1007/s00018-012-1039-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Revised: 05/13/2012] [Accepted: 05/23/2012] [Indexed: 12/13/2022]
Abstract
The Na(+),K(+)-ATPase, or sodium pump, is well known for its role in ion transport across the plasma membrane of animal cells. It carries out the transport of Na(+) ions out of the cell and of K(+) ions into the cell and thus maintains electrolyte and fluid balance. In addition to the fundamental ion-pumping function of the Na(+),K(+)-ATPase, recent work has suggested additional roles for Na(+),K(+)-ATPase in signal transduction and biomembrane structure. Several signaling pathways have been found to involve Na(+),K(+)-ATPase, which serves as a docking station for a fast-growing number of protein interaction partners. In this review, we focus on Na(+),K(+)-ATPase as a signal transducer, but also briefly discuss other Na(+),K(+)-ATPase protein-protein interactions, providing a comprehensive overview of the diverse signaling functions ascribed to this well-known enzyme.
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Affiliation(s)
- Linda Reinhard
- Danish National Research Foundation, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Department of Molecular Biology and Genetics, 8000 Aarhus C, Denmark
| | - Henning Tidow
- Danish National Research Foundation, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Department of Molecular Biology and Genetics, 8000 Aarhus C, Denmark
| | - Michael J. Clausen
- Danish National Research Foundation, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Department of Molecular Biology and Genetics, 8000 Aarhus C, Denmark
| | - Poul Nissen
- Danish National Research Foundation, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Department of Molecular Biology and Genetics, 8000 Aarhus C, Denmark
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Johar K, Priya A, Wong-Riley MTT. Regulation of Na(+)/K(+)-ATPase by nuclear respiratory factor 1: implication in the tight coupling of neuronal activity, energy generation, and energy consumption. J Biol Chem 2012; 287:40381-90. [PMID: 23048038 DOI: 10.1074/jbc.m112.414573] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND NRF-1 regulates mediators of neuronal activity and energy generation. RESULTS NRF-1 transcriptionally regulates Na(+)/K(+)-ATPase subunits α1 and β1. CONCLUSION NRF-1 functionally regulates mediators of energy consumption in neurons. SIGNIFICANCE NRF-1 mediates the tight coupling of neuronal activity, energy generation, and energy consumption at the molecular level. Energy generation and energy consumption are tightly coupled to neuronal activity at the cellular level. Na(+)/K(+)-ATPase, a major energy-consuming enzyme, is well expressed in neurons rich in cytochrome c oxidase, an important enzyme of the energy-generating machinery, and glutamatergic receptors that are mediators of neuronal activity. The present study sought to test our hypothesis that the coupling extends to the molecular level, whereby Na(+)/K(+)-ATPase subunits are regulated by the same transcription factor, nuclear respiratory factor 1 (NRF-1), found recently by our laboratory to regulate all cytochrome c oxidase subunit genes and some NMDA and AMPA receptor subunit genes. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation, promoter mutational analysis, and real-time quantitative PCR, NRF-1 was found to functionally bind to the promoters of Atp1a1 and Atp1b1 genes but not of the Atp1a3 gene in neurons. The transcripts of Atp1a1 and Atp1b1 subunit genes were up-regulated by KCl and down-regulated by tetrodotoxin. Atp1b1 is positively regulated by NRF-1, and silencing of NRF-1 with small interference RNA blocked the up-regulation of Atp1b1 induced by KCl, whereas overexpression of NRF-1 rescued these transcripts from being suppressed by tetrodotoxin. On the other hand, Atp1a1 is negatively regulated by NRF-1. The binding sites of NRF-1 on Atp1a1 and Atp1b1 are conserved among mice, rats, and humans. Thus, NRF-1 regulates key Na(+)/K(+)-ATPase subunits and plays an important role in mediating the tight coupling between energy consumption, energy generation, and neuronal activity at the molecular level.
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Affiliation(s)
- Kaid Johar
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Yu HM, Wang TC. Mechanism of cisplatin resistance in human urothelial carcinoma cells. Food Chem Toxicol 2012; 50:1226-37. [PMID: 22326969 DOI: 10.1016/j.fct.2012.01.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 10/31/2011] [Accepted: 01/27/2012] [Indexed: 12/31/2022]
Abstract
An isogenic pair of cisplatin-susceptible (NTUB1) and -resistant (NTUB1/P) human urothelial carcinoma cell lines was used to elucidate the mechanism of cisplatin resistance. The significantly lower intracellular platinum (IP) concentration, which resulted from the decreased cisplatin uptake, was found in NTUB1/P cells. The enhancement of IP concentration did not increase the susceptibility of NTUB1/P cells to cisplatin treatment. The reduction of IP concentration as well was unable to enhance the cisplatin-resistance in susceptible NTUB1 cells. This indicated that reduction of IP concentration was not the account for the development of cisplatin resistance here. Instead, the over expression of anti-apoptotic Bcl-2, anti-oxidative heme oxygenase-1 (HO-1) and cell cycle regulator p16INK4 seemed to be more important for the gaining of cisplatin in these human urothelial carcinoma cell.
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Affiliation(s)
- Hui-Min Yu
- Graduate Institute of Life Sciences, National Defense Medical Center, 161Minquan E. Road, Section 6, Neihu Dist., Taipei City 114, Taiwan, ROC.
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Bøttger P, Doğanlı C, Lykke-Hartmann K. Migraine- and dystonia-related disease-mutations of Na+/K+-ATPases: relevance of behavioral studies in mice to disease symptoms and neurological manifestations in humans. Neurosci Biobehav Rev 2011; 36:855-71. [PMID: 22067897 DOI: 10.1016/j.neubiorev.2011.10.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 10/20/2011] [Accepted: 10/26/2011] [Indexed: 10/15/2022]
Abstract
The two autosomal dominantly inherited neurological diseases: familial hemiplegic migraine type 2 (FHM2) and familial rapid-onset of dystonia-parkinsonism (Familial RDP) are caused by in vivo mutations of specific alpha subunits of the sodium-potassium pump (Na(+)/K(+)-ATPase). Intriguingly, patients with classical FHM2 and RDP symptoms additionally suffer from other manifestations, such as epilepsy/seizures and developmental disabilities. Recent studies of FHM2 and RDP mouse models provide valuable tools for dissecting the vital roles of the Na(+)/K(+)-ATPases, and we discuss their relevance to the complex patient symptoms and manifestations. Thus, it is interesting that mouse models targeting a specific α-isoform cause different, although still comparable, phenotypes consistent with classical symptoms and other manifestations observed in FHM2 and RDP patients. This review highlights that use of mouse models have broad potentials for future research concerning migraine and dystonia-related diseases, which will contribute towards understanding the, yet unknown, pathophysiologies.
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Affiliation(s)
- Pernille Bøttger
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Denmark; Department of Biomedicine, Aarhus University, Ole Worms Allé 3, Aarhus C, Denmark
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Xie XY, Zhang B, Li JH, Fan QX, Zhang Y, Mu DG, Li WP, Xu M, Zhao PT, Jin FG, Li ZC. Sodium tanshinone iia sulfonate attenuates seawater aspiration-induced acute pulmonary edema by up-regulating Na(+),K(+)-ATPase activity. Exp Lung Res 2011; 37:482-91. [PMID: 21797801 DOI: 10.3109/01902148.2011.594144] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Relieving pulmonary edema is the key of a successful treatment to seawater drowning. Sodium tanshinone IIA sulfonate (STS) has been observed to reduce lung edema from lipopolysaccharide (LPS)-induced lung injury. In this study the authors investigated whether STS attenuates seawater aspiration-induced acute pulmonary edema, and examined the effects of sodium-potassium adensosine triphosphatase (Na(+),K(+)-ATPase) on it. Seawater was instilled through an endotracheal tube. The anesthetized and spontaneously breathing rats received STS intraperitoneally after seawater aspiration. Pao(2), lung wet-to-dry weight ratio, and pulmonary microvascular permeability were tested. The authors explored the effects of STS on the expression and activity of Na(+),K(+)-ATPase in vivo and in vitro. Additionally, the authors investigated the role of the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway in the stimulation of Na(+),K(+)-ATPase by STS. The results showed that STS significantly improved hypoxemia, attenuated lung edema, and alleviated seawater-induced lung injury in vivo. Both in vivo and in vitro, it was observed that STS up-regulated the expression and activity of Na(+),K(+)-ATPase. ERK1/2 inhibitor partially blocked the effects of STS on Na(+),K(+)-ATPase activity in alveolar type II cells following seawater incubation. These results indicated that STS could improve seawater aspiration-induced acute pulmonary edema by up-regulating Na(+),K(+)-ATPase activity, and the ERK1/2 signaling pathway may be involved in it.
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Affiliation(s)
- Xiao-Yan Xie
- Department of Respiratory Medicine, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, PR China
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Tokhtaeva E, Sachs G, Vagin O. Diverse pathways for maturation of the Na,K-ATPase β1 and β2 subunits in the endoplasmic reticulum of Madin-Darby canine kidney cells. J Biol Chem 2010; 285:39289-302. [PMID: 20937802 PMCID: PMC2998159 DOI: 10.1074/jbc.m110.172858] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 10/05/2010] [Indexed: 01/05/2023] Open
Abstract
Proper folding of the Na,K-ATPase β subunits followed by assembly with the α subunits is necessary for their export from the endoplasmic reticulum (ER). Here we examine roles of the ER lectin chaperone, calnexin, and non-lectin chaperone, BiP, in folding and quality control of the β(1) and β(2) subunits in Madin-Darby canine kidney cells. Short term prevention of glycan-calnexin interactions by castanospermine slightly increases ER retention of β(1), suggesting minor involvement of calnexin in subunit folding. However, both prolonged incubation with castanospermine and removal of N-glycosylation sites do not affect the α(1)-assembly or trafficking of β(1) but increase the amount of the β(1)-bound BiP, showing that BiP can compensate for calnexin in assisting β(1) folding. In contrast to β(1), prevention of either N-glycosylation or glycan-calnexin interactions abolishes the α(1)-assembly and export of β(2) from the ER despite increased β(2)-BiP binding. Mutations in the α(1)-interacting regions of β(1) and β(2) subunits impair α(1) assembly but do not affect folding of the β subunits tested by their sensitivity to trypsin. At the same time, these mutations increase the amount of β-bound BiP but not of β-bound calnexin and increase ER retention of both β-isoforms. BiP, therefore, prevents the ER export of folded but α(1)-unassembled β subunits. These α(1)-unassembled β subunits are degraded faster than α(1)-bound β subunits, preventing ER overload. In conclusion, folding of the β(1) and β(2) subunits is assisted predominantly by BiP and calnexin, respectively. Folded β(1) and β(2) either assemble with α(1) or bind BiP. The α(1)-bound β subunits traffic to the Golgi, whereas BiP-bound β subunits are retained and degraded in the ER.
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Affiliation(s)
- Elmira Tokhtaeva
- From the Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California 90073
| | - George Sachs
- From the Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California 90073
| | - Olga Vagin
- From the Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California 90073
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van der Velden LM, Wichers CGK, van Breevoort AED, Coleman JA, Molday RS, Berger R, Klomp LWJ, van de Graaf SFJ. Heteromeric interactions required for abundance and subcellular localization of human CDC50 proteins and class 1 P4-ATPases. J Biol Chem 2010; 285:40088-96. [PMID: 20947505 DOI: 10.1074/jbc.m110.139006] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Members of the P(4) family of P-type ATPases (P(4)-ATPases) are believed to function as phospholipid flippases in complex with CDC50 proteins. Mutations in the human class 1 P(4)-ATPase gene ATP8B1 cause a severe syndrome characterized by impaired bile flow (intrahepatic cholestasis), often leading to end-stage liver failure in childhood. In this study, we determined the specificity of human class 1 P(4)-ATPase interactions with CDC50 proteins and the functional consequences of these interactions on protein abundance and localization of both protein classes. ATP8B1 and ATP8B2 co-immunoprecipitated with CDC50A and CDC50B, whereas ATP8B4, ATP8A1, and ATP8A2 associated only with CDC50A. ATP8B1 shifted from the endoplasmic reticulum (ER) to the plasma membrane upon coexpression of CDC50A or CDC50B. ATP8A1 and ATP8A2 translocated from the ER to the Golgi complex and plasma membrane upon coexpression of CDC50A, but not CDC50B. ATP8B2 and ATP8B4 already displayed partial plasma membrane localization in the absence of CDC50 coexpression but displayed a large increase in plasma membrane abundance upon coexpression of CDC50A. ATP8B3 did not bind CDC50A and CDC50B and was invariably present in the ER. Our data show that interactions between CDC50 proteins and class 1 P(4)-ATPases are essential for ER exit and stability of both subunits. Furthermore, the subcellular localization of the complex is determined by the P(4)-ATPase, not the CDC50 protein. The interactions of CDC50A and CDC50B with multiple members of the human P(4)-ATPase family suggest that these proteins perform broader functions in human physiology than thus far assumed.
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Affiliation(s)
- Lieke M van der Velden
- Department of Metabolic and Endocrine Diseases, Universitair Medisch Centrum Utrecht, AB Utrecht, The Netherlands.
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37
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Tokhtaeva E, Sachs G, Vagin O. Assembly with the Na,K-ATPase alpha(1) subunit is required for export of beta(1) and beta(2) subunits from the endoplasmic reticulum. Biochemistry 2009; 48:11421-31. [PMID: 19764716 DOI: 10.1021/bi901438z] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The level of the heterodimeric Na,K-ATPase is tightly controlled in epithelia to maintain appropriate transport function. The catalytic Na,K-ATPase alpha subunit is not able to exit the ER or catalyze ion transport unless assembled with the beta subunit. However, requirements for the ER exit of the Na,K-ATPase beta subunit that plays an additional, ion-transport-independent, role in intercellular adhesion are not clear. Exogenous beta(1) or beta(2) subunits expressed in renal MDCK cells replace endogenous beta(1) subunits in the alpha-beta complexes in the ER, resulting in a decrease in the amount of the alpha(1)-bound endogenous beta(1) subunits by 47-61% with no change in the amount of alpha(1) subunits. Disruption of the alpha(1)-beta association by mutations in defined alpha(1)-interacting regions of either beta(1) or beta(2) subunits results in the ER retention and rapid degradation of unassembled mutants. Hence, the ER quality control system allows export only of assembled alpha-beta complexes to the Golgi, thereby maintaining an equimolar ratio of alpha and beta subunits in the plasma membrane, whereas the number of alpha(1) subunits in the ER determines the amount of the alpha-beta complexes.
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Affiliation(s)
- Elmira Tokhtaeva
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, USA
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Valente RC, Capella LS, Oliveira MMM, Nunes-Lima LT, Cruz FCM, Palmieri RR, Lopes AG, Capella MAM. Diverse actions of ouabain and its aglycone ouabagenin in renal cells. Cell Biol Toxicol 2009; 26:201-13. [PMID: 19757104 DOI: 10.1007/s10565-009-9136-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 08/20/2009] [Indexed: 12/15/2022]
Abstract
The cellular actions of ouabain are complex and involve different pathways, depending on the cell type and experimental conditions. Several studies have reported that Madin-Darby canine kidney (MDCK) cellular sensitivity to ouabain is not related to Na-K-ATPase inhibition, and others showed that some cell types, such as Ma104, are resistant to ouabain toxicity albeit their Na-K-ATPase isoforms possess high affinity for this glycoside. We describe here that the effects of ouabain and ouabagenin also diverge in MDCK and Ma104 cells, being MDCK cells more resistant to ouabagenin, while Ma104 cells are resistant to both molecules. This feature seems to correlate with induction of cell signaling, since ouabain, but not ouabagenin, induced an intense and sustained increase in tyrosine phosphorylation levels in MDCK cells. Moreover, ouabain-induced phosphorylation in Ma104 cells was approximately half than that observed in MDCK cells. The proportion between alpha and beta subunits of Na-K-ATPase was similar in MDCK cells, though Ma104 cells presented more alpha subunits, located mainly at the cytoplasm. Furthermore, a fluorescent ouabain-analog labeled mainly the cytoplasm of Ma104 cells, the opposite of that seen in MDCK cells, corroborating the results using anti-Na-K-ATPase antibodies. Hence, the results suggest that ouabain and ouabagenin differ in terms of Na-K-ATPase inhibition and cell signaling activation in MDCK cells. Additionally, MDCK and Ma104 cell lines respond differently to ouabain, perhaps due to an intrinsic ability of this glycoside to selectively reach the cytoplasm of Ma104 cells.
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Affiliation(s)
- Raphael C Valente
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
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Madsen SS, Kiilerich P, Tipsmark CK. Multiplicity of expression of Na+,K+-ATPase {alpha}-subunit isoforms in the gill of Atlantic salmon (Salmo salar): cellular localisation and absolute quantification in response to salinity change. ACTA ACUST UNITED AC 2009; 212:78-88. [PMID: 19088213 DOI: 10.1242/jeb.024612] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ability to reverse the net direction of gill ion transport in response to a salinity change is critical for euryhaline teleosts and involves a complex cellular and molecular remodelling of the gill epithelium. The present study aimed to clarify the cellular localisation and exact quantitative inter-relationship of Na(+),K(+)-ATPase alpha- and beta-subunit transcripts in Atlantic salmon gill during salinity change. The combined expression level of all alpha-isoforms in the gill increased by 100% after freshwater (FW) to seawater (SW) transfer. The alpha(1a) and alpha(1b) isoforms were both in the range 1-6 amol 20 ng(-1) total RNA; alpha(1a) decreased and alpha(1b) increased after SW-transfer, their ratio changing from 5:1 in FW to 0.26:1 in SW. The alpha(1c) and alpha(3) levels were 10- and 100-fold lower, respectively. The beta(1)-subunit mRNA level was 0.1-0.3 amol 20 ng(-1) total RNA, thus much lower than the sum of alpha-subunits. Even though increasing 3-fold after SW-transfer, beta-subunit availability may still limit functional pump synthesis. The mRNAs of the predominant alpha(1a) and alpha(1b) isoforms were localised by in situ hybridisation in specific gill cells of both FW and SW salmon. Labelling occurred mainly in presumed chloride cells and cells deep in the filament but occasionally also on lamellae. Overall, the salinity-induced variation in labelling pattern and intensity matched the quantification data. In conclusion, the predominant switching of Na(+),K(+)-ATPase alpha-subunit isoform mRNA during salinity acclimation reflects a marked remodelling of mitochondrion-rich cells (MRCs) in the gill and probably tuning of the pump performance to accomplish a net reversal of gill ion transport in hypo- and hypertonic environments.
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Affiliation(s)
- Steffen S Madsen
- Institute of Biology, University of Southern Denmark, 5230 Odense M, Denmark.
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Pihakaski-Maunsbach K, Nonaka S, Maunsbach AB. Expression and trafficking of the gamma subunit of Na,K-ATPase in hypertonically challenged IMCD3 cells. Acta Histochem Cytochem 2008; 41:105-14. [PMID: 18787637 PMCID: PMC2532601 DOI: 10.1267/ahc.08018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Accepted: 06/20/2008] [Indexed: 11/22/2022] Open
Abstract
The gamma subunit (FXYD2) of Na,K-ATPase is an important regulator of the sodium pump. In this investigation we have analysed the trafficking of gamma to the plasma membrane in cultures of inner medullary collecting duct cells (IMCD3) following acute hypertonic challenge and brefeldin A (BFA) treatment. Following hypertonic challenging for 24 hr immunofluorescence labeling revealed initial co-localization of the gamma subunit and 58K Golgi protein in the cytoplasm, but no co-localization of alpha1 and Golgi protein. Exposure of the challenged cells to BFA prevented the subsequent incorporation of gamma into the basolateral plasma membrane. The gamma subunit instead remained in cytoplasmic vesicles while cell proliferation and cell viability decreased simultaneously. Following removal of BFA from the hypertonic medium the IMCD3 cells recovered with distinct expression of gamma in the basolateral membrane. The alpha1 subunit was only marginally influenced by BFA. The results demonstrate that the gamma subunit trafficks to the plasma membrane via the Golgi apparatus, despite the absence of a signal sequence. The results also suggest that the gamma and alpha subunits do not traffic together to the plasma membrane, and that the gamma and alpha subunit have different turnover rates during these experimental conditions.
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Affiliation(s)
| | - Shoichi Nonaka
- The Water and Salt Research Center, Department of Cell Biology, Institute of Anatomy, University of Aarhus
- Department of Urology, Saitama Medical University
| | - Arvid B. Maunsbach
- The Water and Salt Research Center, Department of Cell Biology, Institute of Anatomy, University of Aarhus
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41
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Inge LJ, Rajasekaran SA, Yoshimoto K, Mischel PS, McBride W, Landaw E, Rajasekaran AK. Evidence for a potential tumor suppressor role for the Na,K-ATPase beta1-subunit. Histol Histopathol 2008; 23:459-67. [PMID: 18228203 PMCID: PMC2779022 DOI: 10.14670/hh-23.459] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Na,K-ATPase, consisting of two essential subunits (alpha, beta), plays a critical role in the regulation of ion homeostasis in mammalian cells. Recent studies indicate that reduced expression of the beta1 isoform (NaK-beta1) is commonly observed in carcinoma and is associated with events involved in cancer progression. In this study, we present evidence that repletion of NaK-beta1 in Moloney sarcoma virus-transformed Madin-Darby canine kidney cells (MSV-MDCK), a highly tumorigenic cell line, inhibits anchorage independent growth and suppresses tumor formation in immunocompromised mice. Additionally, using an in vitro cell-cell aggregation assay, we showed that cell aggregates of NaK-beta1 subunit expressing MSV-MDCK cells have reduced extracellular regulated kinase (ERK) 1/2 activity compared with parental MSV-MDCK cells. Finally, using immunohistochemistry and fully quantitative image analysis approaches, we showed that the levels of phosphorylated ERK 1/2 are inversely correlated to the NaK-beta1 levels in the tumors. These findings reveal for the first time that NaK-beta1 has a potential tumor-suppressor function in epithelial cells.
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Affiliation(s)
- L J Inge
- Department of Pathology and Laboratory Medicine, Molecular Biology Institute, Jonsson Comprehensive Cancer Center-David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Dürr KL, Tavraz NN, Zimmermann D, Bamberg E, Friedrich T. Characterization of Na,K-ATPase and H,K-ATPase Enzymes with Glycosylation-Deficient β-Subunit Variants by Voltage-Clamp Fluorometry in Xenopus Oocytes. Biochemistry 2008; 47:4288-97. [DOI: 10.1021/bi800092k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katharina L. Dürr
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Neslihan N. Tavraz
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Dirk Zimmermann
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Ernst Bamberg
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Thomas Friedrich
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
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Aturaliya RN, Fink JL, Davis MJ, Teasdale MS, Hanson KA, Miranda KC, Forrest ARR, Grimmond SM, Suzuki H, Kanamori M, Kai C, Kawai J, Carninci P, Hayashizaki Y, Teasdale RD. Subcellular localization of mammalian type II membrane proteins. Traffic 2007; 7:613-25. [PMID: 16643283 DOI: 10.1111/j.1600-0854.2006.00407.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Application of a computational membrane organization prediction pipeline, MemO, identified putative type II membrane proteins as proteins predicted to encode a single alpha-helical transmembrane domain (TMD) and no signal peptides. MemO was applied to RIKEN's mouse isoform protein set to identify 1436 non-overlapping genomic regions or transcriptional units (TUs), which encode exclusively type II membrane proteins. Proteins with overlapping predicted InterPro and TMDs were reviewed to discard false positive predictions resulting in a dataset comprised of 1831 transcripts in 1408 TUs. This dataset was used to develop a systematic protocol to document subcellular localization of type II membrane proteins. This approach combines mining of published literature to identify subcellular localization data and a high-throughput, polymerase chain reaction (PCR)-based approach to experimentally characterize subcellular localization. These approaches have provided localization data for 244 and 169 proteins. Type II membrane proteins are localized to all major organelle compartments; however, some biases were observed towards the early secretory pathway and punctate structures. Collectively, this study reports the subcellular localization of 26% of the defined dataset. All reported localization data are presented in the LOCATE database (http://www.locate.imb.uq.edu.au).
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Affiliation(s)
- Rajith N Aturaliya
- Institute for Molecular Bioscience and ARC Centre in Bioinformatics, University of Queensland, St. Lucia, Queensland 4072, Australia
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44
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Murphy KT, Aughey RJ, Petersen AC, Clark SA, Goodman C, Hawley JA, Cameron-Smith D, Snow RJ, McKenna MJ. Effects of endurance training status and sex differences on Na+,K+-pump mRNA expression, content and maximal activity in human skeletal muscle. Acta Physiol (Oxf) 2007; 189:259-69. [PMID: 17305706 DOI: 10.1111/j.1748-1716.2006.01635.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM This study investigated the effects of endurance training status and sex differences on skeletal muscle Na+,K+-pump mRNA expression, content and activity. METHODS Forty-five endurance-trained males (ETM), 11 recreationally active males (RAM), and nine recreationally active females (RAF) underwent a vastus lateralis muscle biopsy. Muscle was analysed for Na+,K+-pump alpha1, alpha2, alpha3, beta1, beta2 and beta3 isoform mRNA expression (real-time reverse transcription-polymerase chain reaction), content ([3H]-ouabain-binding site) and maximal activity (3-O-methylfluorescein phosphatase, 3-O-MFPase). RESULTS ETM demonstrated lower alpha1, alpha3, beta2 and beta3 mRNA expression by 74%, 62%, 70% and 82%, respectively, than RAM (P<0.04). In contrast, [3H]-ouabain binding and 3-O-MFPase activity were each higher in ETM than in RAM, by 16% (P<0.03). RAM demonstrated a 230% and 364% higher alpha3 and beta3 mRNA expression than RAF, respectively (P<0.05), but no significant sex differences were found for alpha1, alpha2, beta1 or beta2 mRNA, [3H]-ouabain binding or 3-O-MFPase activity. No significant correlation was found between years of endurance training and either [3H]-ouabain binding or 3-O-MFPase activity. Significant but weak correlations were found between the number of training hours per week and 3-O-MFPase activity (r=0.31, P<0.02) and between incremental exercise VO2(peak)) and both [3H]-ouabain binding (r=0.33, P<0.01) and 3-O-MFPase activity (r=0.28, P<0.03). CONCLUSIONS Isoform-specific differences in Na+,K+-pump mRNA expression were found with both training status and sex differences, but only training status influenced Na+,K+-pump content and maximal activity in human skeletal muscle.
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Affiliation(s)
- K T Murphy
- Muscle, Ions and Exercise Group, School of Human Movement, Recreation and Performance, Centre for Ageing, Rehabilitation, Exercise and Sport Science (CARES), Victoria University, Melbourne, Vic., Australia
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45
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Abstract
The Na,K-adenosine triphosphatase (ATPase), or sodium pump, has been well studied for its role in the regulation of ion homeostasis in mammalian cells. Recent studies suggest that Na,K-ATPase might have multiple functions such as a role in the regulation of tight junction structure and function, induction of polarity, regulation of actin dynamics, control of cell movement, and cell signaling. These functions appear to be modulated by Na,K-ATPase enzyme activity as well as protein-protein interactions of the alpha and beta subunits. In this review we attempt to differentiate functions associated with enzyme activity and subunit interactions. In addition, the consequence of impaired Na,K-ATPase function or reduced subunit expression levels in kidney diseases such as cancer, tubulointerstitial fibrosis, and ischemic nephropathy are discussed.
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Affiliation(s)
- Sigrid A Rajasekaran
- Department of Pathology and Laboratory Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA
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46
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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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47
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Lian WN, Wu TW, Dao RL, Chen YJ, Lin CH. Deglycosylation of Na+/K+-ATPase causes the basolateral protein to undergo apical targeting in polarized hepatic cells. J Cell Sci 2005; 119:11-22. [PMID: 16339171 DOI: 10.1242/jcs.02706] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Polarized epithelia, such as hepatocytes, target their integral membrane proteins to specific apical or basolateral membrane domains during or after biogenesis. The roles played by protein glycosylation in this sorting process remain controversial. We report here that deglycosylation treatments in well-polarized hepatic cells by deglycosylation drugs, or by site-directed mutagenesis of the N-linked-glycosylation residues, all cause the Na+/K+-ATPase beta-subunit to traffic from the native basolateral to the apical/canalicular domain. Deglycosylated beta-subunits are still able to bind and therefore transport the catalytic alpha-subunits to the aberrant apical location. Such apical targeting is mediated via the indirect transcytosis pathway. Cells containing apical Na+/K+-ATPase appear to be defective in maintaining the ionic gradient across the plasma membrane and in executing hepatic activities that are dependent upon the ionic homeostasis such as canalicular excretion.
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Affiliation(s)
- Wei-Nan Lian
- Institute of Microbiology and Immunology, National Yang-Ming University, 155 Sec. 2 Linong Street, Taipei 112, Taiwan
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48
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Chen JQ, Contreras RG, Wang R, Fernandez SV, Shoshani L, Russo IH, Cereijido M, Russo J. Sodium/potasium ATPase (Na+, K+-ATPase) and ouabain/related cardiac glycosides: a new paradigm for development of anti- breast cancer drugs? Breast Cancer Res Treat 2005; 96:1-15. [PMID: 16322895 DOI: 10.1007/s10549-005-9053-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 08/11/2005] [Indexed: 11/30/2022]
Abstract
Prolonged exposure to 17beta-estradiol (E2) is a key etiological factor for human breast cancer. The biological effects and carcinogenic effects of E2 are mediated via estrogen receptors (ERs), ERalpha and ERbeta. Anti-estrogens, e.g. tamoxifen, and aromatase inhibitors have been used to treat ER-positive breast cancer. While anti-estrogen therapy is initially successful, a major problem is that most tumors develop resistance and the disease ultimately progresses, pointing to the need of developing alternative drugs targeting to other critical targets in breast cancer cells. We have identified that Na+, K+-ATPase, a plasma membrane ion pump, has unique/valuable properties that could be used as a potentially important target for breast cancer treatment: (a) it is a key player of cell adhesion and is involved in cancer progression; (b) it serves as a versatile signal transducer and is a target for a number of hormones including estrogens and (d) its aberrant expression and activity are implicated in the development and progression of breast cancer. There are several lines of evidence indicating that ouabain and related digitalis (the potent inhibitors of Na+, K+-ATPase) possess potent anti-breast cancer activity. While it is not clear how the suggested anti-cancer activity of these drugs work, several observations point to ouabain and digitalis as being potential ER antagonists. We critically reviewed many lines of evidence and postulated a novel concept that Na+, K+-ATPase in combination with ERs could be important targets of anti-breast cancer drugs. Modulators, e.g. ouabain and related digitalis could be useful to develop valuable anti-breast cancer drugs as both Na+, K+-ATPase inhibitors and ER antagonists.
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Affiliation(s)
- Jin-Qiang Chen
- Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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49
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Petersen AC, Murphy KT, Snow RJ, Leppik JA, Aughey RJ, Garnham AP, Cameron-Smith D, McKenna MJ. Depressed Na+-K+-ATPase activity in skeletal muscle at fatigue is correlated with increased Na+-K+-ATPase mRNA expression following intense exercise. Am J Physiol Regul Integr Comp Physiol 2005; 289:R266-74. [PMID: 15790751 DOI: 10.1152/ajpregu.00378.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether depressed muscle Na+-K+-ATPase activity with exercise reflected a loss of Na+-K+-ATPase units, the time course of its recovery postexercise, and whether this depressed activity was related to increased Na+-K+-ATPase isoform gene expression. Fifteen subjects performed fatiguing, knee extensor exercise at ∼40% maximal work output per contraction. A vastus lateralis muscle biopsy was taken at rest, fatigue, 3 h, and 24 h postexercise and analyzed for maximal Na+-K+-ATPase activity via 3- O-methylfluorescein phosphatase (3- O-MFPase) activity, Na+-K+-ATPase content via [3H]ouabain binding sites, and Na+-K+-ATPase α1-, α2-, α3-, β1-, β2- and β3-isoform mRNA expression by real-time RT-PCR. Exercise [352 (SD 267) s] did not affect [3H]ouabain binding sites but decreased 3- O-MFPase activity by 10.7 (SD 8)% ( P < 0.05), which had recovered by 3 h postexercise, without further change at 24 h. Exercise elevated α1-isoform mRNA by 1.5-fold at fatigue ( P < 0.05). This increase was inversely correlated with the percent change in 3- O-MFPase activity from rest to fatigue (%Δ3- O-MFPaserest-fatigue) ( r = −0.60, P < 0.05). The average postexercise (fatigue, 3 h, 24 h) α1-isoform mRNA was increased 1.4-fold ( P < 0.05) and approached a significant inverse correlation with %Δ3- O-MFPaserest-fatigue( r = −0.56, P = 0.08). Exercise elevated α2-isoform mRNA at fatigue 2.5-fold ( P < 0.05), which was inversely correlated with %Δ3- O-MFPaserest-fatigue( r = −0.60, P = 0.05). The average postexercise α2-isoform mRNA was increased 2.2-fold ( P < 0.05) and was inversely correlated with the %Δ3- O-MFPaserest-fatigue( r = −0.68, P < 0.05). Nonsignificant correlations were found between %Δ3- O-MFPaserest-fatigueand other isoforms. Thus acute exercise transiently decreased Na+-K+-ATPase activity, which was correlated with increased Na+-K+-ATPase gene expression. This suggests a possible signal-transduction role for depressed muscle Na+-K+-ATPase activity with exercise.
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Affiliation(s)
- A C Petersen
- Muscle, Ions and Exercise Group, School of Human Movement, Recreation and Performance, Centre for Ageing, Rehabilitation, Exercise, and Sport, Victoria University of Technology, PO Box 14428, MCMC, Melbourne, Victoria, Australia 8001
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50
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Brauer PR, Sanmann JN, Petzel DH. Effects of warm acclimation on Na+,K+-ATPase α-subunit expression in chloride cells of Antarctic fish. ACTA ACUST UNITED AC 2005; 285:600-9. [PMID: 15912523 DOI: 10.1002/ar.a.20203] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The teleosts Trematomus bernacchii thrive in southern oceanic waters with temperatures below 0 degrees C. These fish have serum osmolalities almost double those found in fish of temperate waters, thereby lowering their serum's freezing point and the energy needed for ionic homeostasis. Upon warm acclimation to 4 degrees C, T. bernacchii decrease their serum osmolality and increase the Na+,K+-ATPase activity in their gills. Na+,K+-ATPase alpha1-, alpha2-, and alpha3-subunit isoforms are expressed in the gills of T. bernacchii and it is thought that Na+,K+-ATPase subunit composition in chloride cells changes with warm acclimation. Using immunohistochemistry, we compared the number of chloride cells expressing various alpha-isoforms of the Na+,K+-ATPase in the gills of cold- and warm-acclimated T. bernacchii. We found no change in the number of alpha2- or alpha3-immunopositive cells in warm-acclimated fish gills or in the number of cells immunopositive for the Na+,K+,2Cl- cotransporter. However, the number of pan-alpha-immunopositive (recognizing all three alpha-isoforms) and alpha1-immunopositive cells both increased in warm-acclimated fish. This suggests that changes in the number of alpha1-isoform-expressing chloride cells could contribute to the increased Na+,K+-ATPase activity that occurs with warm-acclimation.
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Affiliation(s)
- Philip R Brauer
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178, USA.
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