Pretranslational regulation of Na-K-ATPase in cultured canine kidney cells by low K+

Bowen, Jesse W.; McDonough, Alicia A.

doi:10.1152/ajpcell.1987.252.2.c179

Cited by 82 publications

(40 citation statements)

References 44 publications

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“…Taken together, these experiments provide no evidence for a role of increased cell Na ϩ as the mediator of the ␥-subunit response. These results could be considered unexpected because maneuvers that increase cell Na ϩ , such as depletion of extracellular K ϩ or the use of Na ϩ ionophores, have been described to increase Na͞K-ATPase activity (13). It is, thus, very possible that the mechanisms that control the synthesis of the ␣ 1 and ␤ subunits of Na͞K-ATPase are distinct from those mechanisms involved in the regulation of the ␥-subunit synthesis.…”

Section: Discussionmentioning

confidence: 98%

Chloride, not sodium, stimulates expression of the γ subunit of Na/K-ATPase and activates JNK in response to hypertonicity in mouse IMCD3 cells

Capasso

Rivard

Enomoto

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Hypertonicity induced by NaCl, but not by urea or mannitol, up-regulates expression of the ␥ subunit of Na͞K-ATPase in cells of the murine inner medullary collecting duct line (IMCD3) by activation of the Jun kinase 2 (JNK2) pathways. We examined the ionic mediators of the osmosensitive response. An increase in osmolality to 550 milliosmoles per kg of water (mosmol͞kgH 2O) for 48 h by replacement of NaCl with choline chloride did not prevent the up-regulation of the ␥ subunit. Neither Na ؉ ionophores nor inhibitors of cellular Na ؉ uptake altered the up-regulation of the ␥ subunit or JNK activation. Changes in cell cation concentrations driven by incubation in low-K ؉ medium were effective in upregulating the ␣1 subunit of Na͞K-ATPase but did not have any effect on the ␥ subunit. The replacement of NaCl with choline chloride did not down-regulate ␥-subunit expression in cells adapted to hypertonicity. In contrast, the replacement of NaCl with sodium acetate, or pretreatment of cells with the Cl ؊ channel inhibitor 5-nitro-2-(3-phenylpropyl-amino)benzoic acid (NPPB) completely blocked ␥-subunit up-regulation, inhibited JNK activation, and caused a significant decrement in cell survival in hypertonic but not isotonic conditions. In adapted cells, replacement of 300 mosmol͞kgH 2O NaCl with sodium acetate resulted in downregulation of the ␥ subunit. In conclusion, we describe a Na ؉ -independent, Cl ؊ -dependent mechanism for hypertonicity-mediated activation of the JNK and the subsequent synthesis of the ␥ subunit of Na͞K-ATPase, which are necessary for cellular survival in these anisotonic conditions.

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Section: Discussionmentioning

confidence: 98%

Chloride, not sodium, stimulates expression of the γ subunit of Na/K-ATPase and activates JNK in response to hypertonicity in mouse IMCD3 cells

Capasso

Rivard

Enomoto

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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“…For instance, the effect of low K ϩ on the Na,K-ATPase had been repeatedly demonstrated in various cell models. Up-regulation of the Na,K-ATPase was observed in MDCK cells (48), , and LLC-PK1 (50) cells grown in serum-supplied medium. However, as demonstrated recently by Yin et al (51), withdrawal of serum (for a period longer than 16 h) from MDCK cultures abolished the effect of low K ϩ , and up-regulation of Na,K-ATPase was partially mimicked by addition of transferrin to the cell culture medium.…”

Section: Discussionmentioning

confidence: 99%

Stress-induced Expression of the γ Subunit (FXYD2) Modulates Na,K-ATPase Activity and Cell Growth

Wetzel

Pascoa

Arystarkhova

2004

Journal of Biological Chemistry

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In kidney, the Na,K-ATPase is associated with a single span protein, the ␥ subunit (FXYD2). Two splice variants are differentially expressed along the nephron and have a differential influence on Na,K-ATPase when stably expressed in mammalian cells in culture. Here we used a combination of gene induction and gene silencing techniques to test the functional impact of ␥ by means other than transfection. NRK-52E cells (of proximal tubule origin) do not express ␥ as a protein under regular tissue culture conditions. However, when they were exposed to hyperosmotic medium, induction of only the ␥a splice variant was observed, which was accompanied by a reduction in the rate of cell division. Kinetic analysis of stable enzyme properties from control (␣1␤1) and hypertonicity-treated cultures (␣1␤1␥a) revealed a significant reduction (up to 60%) of Na,K-ATPase activity measured under V max conditions with little or no change in the amounts of ␣1␤1. This effect as well as the reduction in cell growth rate was practically abolished when ␥ expression was knocked down using specific small interfering RNA duplexes. Surprisingly, a similar induction of endogenous ␥a because of hypertonicity was seen in rat cell lines of other than renal origin: C6 (glioma), PC12 (pheochromocytoma), and L6 (myoblasts). Furthermore, exposure of NRK-52E cells to other stress inducers such as heat shock, exogenous oxidation, and chemical stress also resulted in a selective induction of ␥a. Taken together, the data imply that induction of ␥a may have adaptive value by being a part of a general cellular response to genotoxic stress.

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“…In brief, after cRNA injection, the oocytes were kept in ND10 solution (in mM): NaCl 10, KCl 2, CaCl 2 1.8, MgCl 2 5, tetraethylammonium (TEA-Cl) 10, HEPES-NMDG 10, pH 7.4; elicits an outwards current (I P ) that can be recorded. The (50 µM) strophantidin-sensitive portion of this current is carried by the pumps containing the endogenous Xenopus α-subunit and the current blocked by the subsequent addition of 3 mM ouabain corresponds to that carried by the hybrid pumps containing the ouabain-resistant rat α1-subunit.…”

Section: Methodsmentioning

confidence: 99%

SGK1 increases Na,K-ATP cell-surface expression and function in Xenopus laevis oocytes

Zecevic

Heitzmann

Camargo

et al. 2004

Pfl�gers Archiv European Journal of Physiology

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The Na + -retaining hormone aldosterone increases the cell-surface expression of the luminal epithelial sodium channel (ENaC) and the basolateral Na + pump (Na,K-ATPase) in aldosterone-sensitive distal nephron cells in a coordinated fashion. To address the question of whether aldosterone-induced serum and glucocorticoidregulated kinase-1 (SGK1) might be involved in mediating this regulation of Na,K-ATPase subcellular localization, similar to that of the epithelial Na + channel (ENaC), we co-expressed the Na,K-ATPase (rat α1-and Xenopus laevis β1-subunits) and Xenopus SGK1 in Xenopus oocytes. Measurements of the Na + pump current showed that wild-type SGK1 increases the function of exogenous Na,K-ATPase at the surface of Xenopus oocytes. This appeared to be secondary to an increase in Na,K-ATPase cell-surface expression as visualized by Western blotting of surface-biotinylated proteins. In contrast, the functional surface expression of two other exogenous transporters, the heterodimeric amino acid transporter LAT1-4F2hc and the Na + /phosphate cotransporter NaPi-IIa, was not increased by SGK1 co-expression. The total pool of exogenous Na,K-ATPase was increased by the co-expression of SGK1, and similarly also by ENaC co-expression. This latter effect depended on the [Na + ] of the buffer and was not additive to that of SGK1. When the total Na,KATPase was increased by ENaC co-expression, SGK1 still increased Na,K-ATPase cell-surface expression. These observations in Xenopus oocytes suggest the possibility that SGK1 induction and/or activation could participate in the coordinated regulation of Na,K-ATPase and ENaC cell-surface expression in the aldosterone-sensitive distal nephron.

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Pretranslational regulation of Na-K-ATPase in cultured canine kidney cells by low K+

Cited by 82 publications

References 44 publications

Chloride, not sodium, stimulates expression of the γ subunit of Na/K-ATPase and activates JNK in response to hypertonicity in mouse IMCD3 cells

Chloride, not sodium, stimulates expression of the γ subunit of Na/K-ATPase and activates JNK in response to hypertonicity in mouse IMCD3 cells

Stress-induced Expression of the γ Subunit (FXYD2) Modulates Na,K-ATPase Activity and Cell Growth

SGK1 increases Na,K-ATP cell-surface expression and function in Xenopus laevis oocytes

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