Glucocorticoids regulate NHE-3 transcription in OKP cells
M Baum, M Amemiya, V Dwarakanath… - American Journal …, 1996 - journals.physiology.org
M Baum, M Amemiya, V Dwarakanath, RJ Alpern, OW Moe
American Journal of Physiology-Renal Physiology, 1996•journals.physiology.orgOKP cells express NHE-3, an amiloride-resistant Na+/H+ antiporter, which is likely an
isoform responsible for apical proton secretion by the proximal tubule. We have previously
shown that an amiloride-resistant Na+/H+ antiporter in OKP cells is regulated by
dexamethasone, a synthetic glucocorticoid. The purpose of the present study was to
examine the mechanism for the glucocorticoid-mediated increase in Na+/H+ antiporter
activity. Incubation of OKP cells with 10 (-6) M dexamethasone resulted in a two-to threefold …
isoform responsible for apical proton secretion by the proximal tubule. We have previously
shown that an amiloride-resistant Na+/H+ antiporter in OKP cells is regulated by
dexamethasone, a synthetic glucocorticoid. The purpose of the present study was to
examine the mechanism for the glucocorticoid-mediated increase in Na+/H+ antiporter
activity. Incubation of OKP cells with 10 (-6) M dexamethasone resulted in a two-to threefold …
OKP cells express NHE-3, an amiloride-resistant Na+/H+ antiporter, which is likely an isoform responsible for apical proton secretion by the proximal tubule. We have previously shown that an amiloride-resistant Na+/H+ antiporter in OKP cells is regulated by dexamethasone, a synthetic glucocorticoid. The purpose of the present study was to examine the mechanism for the glucocorticoid-mediated increase in Na+/H+ antiporter activity. Incubation of OKP cells with 10(-6) M dexamethasone resulted in a two- to threefold increase in NHE-3 mRNA abundance. This increase was seen after 4 h of incubation with dexamethasone, a time course similar to that found for Na+/H+ antiporter activity. To examine the mechanism for the increase in NHE-3 mRNA abundance, mRNA half-life and in vitro transcription experiments were performed. NHE-3 mRNA had a half-life of 8 h in control and dexamethasone-treated cells. The rate of in vitro transcription was 1.8-fold greater when OKP cells were treated with dexamethasone. These data suggest that the glucocorticoid-mediated increase in Na+/H+ antiporter activity is due to an increase in NHE-3 gene transcription.
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