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: 288/1/C141    most recent 00343.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science 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 Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Zhang, Y.-H. Articles by Hayslett, J. P. Search for Related Content PubMed PubMed Citation Articles by Zhang, Y.-H. Articles by Hayslett, J. P.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Insulin-induced phosphorylation of ENaC correlates with increased sodium channel function in A6 cells

¹Department of Medicine (Nephrology) and ²Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut

Submitted 15 January 2004 ; accepted in final form 30 August 2004

The purpose of this study was to determine whether there is a correlation between phosphorylation and activity of the epithelial sodium channel (ENaC). The three subunits that form the channel were immunoprecipitated from A6 cells by using specific polyclonal antibodies after labeling cells with ³⁵S or ³²P. When immune complexes were resolved on SDS-PAGE, the -subunit migrated at 85 and 65 kDa, the -subunit at 115 and 100 kDa, and the -subunit at 90 kDa. In the resting state all three subunits were phosphorylated. The -subunit was phosphorylated only in the 65-kDa band, suggesting that the posttranslational modification that gives rise to the rapidly migrating form of is a requirement for phosphorylation. Stimulation with 100 nM insulin for 30 min increased phosphorylation of -, -, and -subunits approximately twofold. Exposure to 1 µM aldosterone for 16 h increased protein abundance and phosphorylation proportionately in the three subunits. When insulin was applied to cells pretreated with aldosterone, phosphorylation was also increased approximately twofold, but the total amount of phosphorylated substrate was larger than in control conditions because of the action of aldosterone. This result might explain the synergistic increase in sodium transport under the same conditions. The protein kinase C inhibitor chelerythrine abolished insulin effects and decreased sodium transport and subunit phosphorylation. Together, our findings suggest that ENaC activity is controlled by subunit phosphorylation in cells that endogenously express the channel and the machinery for hormonal stimulation of sodium transport.

epithelial sodium channel; aldosterone; sodium transport

This article has been cited by other articles:

				H. O'Neill, J. Lebeck, P. B. Collins, T.-H. Kwon, J. Frokiaer, and S. Nielsen Aldosterone-mediated apical targeting of ENaC subunits is blunted in rats with streptozotocin-induced diabetes mellitus Nephrol. Dial. Transplant., May 1, 2008; 23(5): 1546 - 1555. [Abstract] [Full Text] [PDF]

				S. Tiwari, S. Riazi, and C. A. Ecelbarger Insulin's impact on renal sodium transport and blood pressure in health, obesity, and diabetes Am J Physiol Renal Physiol, October 1, 2007; 293(4): F974 - F984. [Abstract] [Full Text] [PDF]

				R. A. Falin and C. U. Cotton Acute Downregulation of ENaC by EGF Involves the PY Motif and Putative ERK Phosphorylation Site J. Gen. Physiol., August 27, 2007; 130(3): 313 - 328. [Abstract] [Full Text] [PDF]

				S. Tiwari, L. Nordquist, V. K. M. Halagappa, and C. A. Ecelbarger Trafficking of ENaC subunits in response to acute insulin in mouse kidney Am J Physiol Renal Physiol, July 1, 2007; 293(1): F178 - F185. [Abstract] [Full Text] [PDF]

				D. Y. Huang, K. M. Boini, B. Friedrich, M. Metzger, L. Just, H. Osswald, P. Wulff, D. Kuhl, V. Vallon, and F. Lang Blunted hypertensive effect of combined fructose and high-salt diet in gene-targeted mice lacking functional serum- and glucocorticoid-inducible kinase SGK1 Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2006; 290(4): R935 - R944. [Abstract] [Full Text] [PDF]