Cleavage of endogenous γENaC and elevated abundance of αENaC are associated with increased Na transport in response to apical fluid volume expansion in human H441 airway epithelial cellsReportar como inadecuado




Cleavage of endogenous γENaC and elevated abundance of αENaC are associated with increased Na transport in response to apical fluid volume expansion in human H441 airway epithelial cells - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Pflügers Archiv - European Journal of Physiology

, Volume 462, Issue 3, pp 431–441

First Online: 12 June 2011Received: 08 April 2011Revised: 20 May 2011Accepted: 23 May 2011

Abstract

Using human H441 airway epithelial cells cultured at air–liquid interface ALI, we have uniquely correlated the functional response to apical fluid volume expansion with the abundance and cleavage of endogenous α- and γENaC proteins in the apical membrane. Monolayers cultured at ALI rapidly elevated Isc when inserted into fluid-filled Ussing chambers. The increase in Isc was not significantly augmented by the apical addition of trypsin, and elevation was abolished by the protease inhibitor aprotinin and an inhibitor of the proprotein convertase, furin. These treatments also increased the IC50 amiloride indicating that the effect was via inhibition of highly Na-selective ENaC channels. Apical fluid, 5–500 μl for 1 h in culture, increased the spontaneous starting Isc in a dose-dependent manner, whilst maximal fluid-induced Isc in the Ussing chamber was unchanged. Apical fluid expansion increased the abundance of 63–65-kDa αENaC proteins in the apical membrane. However, this could not be attributed to increased cleavage as protease inhibitors had no effect on the ratio of cleaved to non-cleaved 90 kDa αENaC proteins. Instead, fluid expansion increased αENaC abundance in the membrane. In contrast, function correlated well with γENaC cleavage at known sites by furin and extracellular proteases. Interestingly, cleavage of γENaC was associated with increased retrieval from the membrane via the proteosomal pathway. Thus, the response to apical fluid volume expansion in H441 airway epithelial cells involves cleavage of γENaC, and changes in α- and γENaC protein abundance at the apical membrane.

KeywordsENaC Protease Na transport Airway Electronic supplementary materialThe online version of this article doi:10.1007-s00424-011-0982-x contains supplementary material, which is available to authorized users.

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Autor: Chong D. Tan - Indusha A. Selvanathar - Deborah L. Baines

Fuente: https://link.springer.com/







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