Aldosterone regulates a 5ʹ variant sgk1 transcript via a shared hormone response element in the sgk1 5ʹ regulatory region. Issue 7 (13th April 2017)

• Record Type: Journal Article
• Authors: Raikwar, Nandita S.; Thomas, Christie P.
• Is Part Of: Physiological reports. Volume 5:Issue 7(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-04-13
• Subjects: Aldosterone -- epithelial Na+ channel -- Na+ transport; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.13221
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: We previously identified a 5ʹ variant alternate transcript of Sgk1 (Sgk1_v3) encoding an NH2 ‐terminal variant Sgk1 isoform, Sgk1_i3 that, like Sgk1, is expressed in the distal convoluted tubule, connecting tubule and collecting duct and can stimulate epithelial Na + transport (Am J Physiol Renal Physiol 303: F1527–F1533, 2012). We now demonstrate that, similar to Sgk1, aldosterone and glucocorticoids stimulate Sgk1_v3 expression in cell lines from the collecting duct and airway epithelia. In mice, short term aldosterone infusion and maneuvers that increase endogenous aldosterone secretion including dietary Na + deprivation and K + loading increases distal nephron Sgk1_v3 expression in vivo. Although Sgk1_v3 has a different 5ʹ proximal regulatory region from Sgk1, the transcription start sites are less than 1000 bp apart. We cloned the 5ʹ regulatory region for Sgk1 and Sgk_v3 upstream of a luciferase gene and by deletion and reporter gene analysis we localized the corticosteroid regulatory region for Sgk1_v3 to a glucocorticoid response element (GRE) that had previously been identified for Sgk1 (Am J Physiol Endo Metab 283: E971–E979, 2002). We tested this element with MR in an MR‐null cell line and demonstrate that aldosterone stimulates Sgk1 and Sgk1_v3 via this GRE. We conclude that corticosteroids stimulate Sgk1 and Sgk1_v3 expression in epithelial cells via activation of a common conserved GRE in the 5ʹ flanking region of Sgk1. Abstract : We demonstrate that aldosterone and glucocorticoids stimulate Sgk1_v3, an alternate transcript of Sgk1, in the collecting duct and airway epithelia. In mice, short term aldosterone infusion, dietary Na+ deprivation and K+ loading increases distal nephron Sgk1_v3 expression in vivo. By deletion and reporter gene analysis we localized the corticosteroid regulatory region for Sgk1_v3 to a glucocorticoid response element (GRE) that had previously been identified for Sgk1. We conclude that corticosteroids stimulate Sgk1 and Sgk1_v3 expression in epithelial cells via activation of a common conserved GRE in the 5ʹ flanking region of Sgk1.