HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 555/2/355    most recent jphysiol.2003.054270v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Summa, V. Articles by Verrey, F. Search for Related Content PubMed PubMed Citation Articles by Summa, V. Articles by Verrey, F.

Institute of Physiology, University of Zurich, CH-8057 Zurich, Switzerland

Short-term aldosterone coordinately regulates the cell-surface expression of luminal epithelial sodium channels (ENaC) and of basolateral Na⁺ pumps (Na⁺,K⁺-ATPase 1–ß1) in aldosterone-sensitive distal nephron (ASDN) cells. To address the question of whether the subcellular localization of the Na⁺,K⁺-ATPase and its regulation by aldosterone depend on subunit isoform-specific structures, we expressed the cardiotonic steroid-sensitive human isoforms 1–3 by retroviral transduction in mouse collecting duct mpkCCD_c14 cells. Each of the three exogenous human isoforms could be detected by Western blotting. Immunofluorescence indicated that the exogenous 1 subunit to a large extent localizes to the basolateral membrane or close to it, whereas much of the 2 subunit remains intracellular. An ouabain-sensitive current carried by exogenous pumps could be detected in apically amphotericin B-permeabilized epithelia expressing human 1 and 2 subunits, but not the 3 subunit. This current displayed a higher apparent Na⁺ affinity in pumps containing human 2 subunits (10 mM) than in pumps containing human 1 (33.2 mM) or endogenous (cardiotonic steroid-resistant) mouse 1 subunits (mean: 16.3 mM). A very low mRNA level of the Na⁺,K⁺-ATPase subunit (FXYD2) in mpkCCD_c14 cells suggested that this ancillary gene product is not responsible for the relatively low apparent Na⁺ affinity measured for a1 subunit-containing pumps. Aldosterone increased the pump current carried by endogenous pumps and by pumps containing the human 1 subunit. In contrast, the current carried by pumps with a human 2 subunit was not stimulated by the same treatment. In summary, quantitative basolateral localization of the Na⁺,K⁺-ATPase and its responsiveness to aldosterone require 1 subunit-specific sequences that differentiate this isoform from the 2 and 3 subunit isoforms.

(Received 31 August 2003; accepted after revision 19 December 2003; first published online 23 December 2003)
Corresponding author F. Verrey: Institute of Physiology, University of Zurich, CH-8057 Zurich, Switzerland. Email: verrey{at}access.unizh.ch

This article has been cited by other articles:

				M. L. Onozato, A. Tojo, N. Kobayashi, A. Goto, H. Matsuoka, and T. Fujita Dual blockade of aldosterone and angiotensin II additively suppresses TGF-{beta} and NADPH oxidase in the hypertensive kidney Nephrol. Dial. Transplant., May 1, 2007; 22(5): 1314 - 1322. [Abstract] [Full Text] [PDF]

				A. Naray-Fejes-Toth, P. M. Snyder, and G. Fejes-Toth The kidney-specific WNK1 isoform is induced by aldosterone and stimulates epithelial sodium channel-mediated Na+ transport PNAS, December 14, 2004; 101(50): 17434 - 17439. [Abstract] [Full Text] [PDF]