Regulation of WNK1 Expression by miR-192 and Aldosterone

Abstract

WNK1 and WNK4 encode two members of the WNK serine-threonine kinase subfamily. Greater WNK1 expression associates with higher BP. A combination of promoters, enhancers, repressors, and insulators regulate WNK1 expression, but whether microRNAs also modulate WNK1 expression is unknown. Here, computational analysis revealed the presence of a target sequence for miR-192 and miR-215 at the same site in the 3Ј untranslated region of the ubiquitous L-and the kidney-specific KS-WNK1. We functionally validated this target sequence by transient transfection and reporter assays. Although we observed expression of both miRs along the distal nephron, only miR-192 regulated endogenous WNK1 ex vivo. Furthermore, a potassium load, sodium depletion, and aldosterone infusion each significantly reduced miR-192 expression in the kidney. Taken together, these results suggest a miR-driven mechanism of gene regulation by aldosterone and a role for miR-192 in the regulation of sodium and potassium balance in the kidney.

Activated mineralocorticoid receptor regulates micro‐RNA‐29b in vascular smooth muscle cells

“…We could identify miR-29b as an aldosterone-dependent miR and subsequently investigated the regulatory mechanism and the potential relevance for vascular pathology per se and for aldosterone-mediated effects in particular. Recently, the MR has been described to regulate miRs involved in physiologic renal MR functions such as salt and water homeostasis (43,44). We were able to identify miR29b as an aldosterone-sensitive "target" that is reduced in abundance in the presences of the hormone in vivo in aorta, primary VSMCs and VSMC lines, but not in endothelial cells.…”

SGK1 regulation by miR-466g in cortical collecting duct cells

“…Recent studies have begun to address the emerging role of miRNAs in regulating ion transport in the distal nephron. Elvira-Matelot et al (13) have demonstrated that low Na ϩ feeding, high K ϩ feeding, or chronic aldosterone infusion of mice decreases renal miR-192 expression. The authors have suggested that aldosterone inhibits miR-192 expression as mechanism for increasing WNK1 (with-no-lysine kinase-1) expression in the CCD; since WNK1 regulates a number of ion transporters and channels in the distal nephron (19,26,35,38), the authors propose that miR-192 partly mediates the regulatory effects of aldosterone and WNK1 on ion transport in the CCD (13).…”

“…Expression of miR-466g was normalized to expression of the control miRNA sno-202. The small nucleolar RNA sno-202 was used as a loading control because expression of this miRNA is unchanged with aldosterone stimulation in mouse kidney (13).…”

“…Human embryonic kidney-293 cells (passages [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] were transfected in 24-well cell culture plates with 37.5 ng of luciferase reporter plasmid, 25 ng ␤-galactosidase control plasmid, and 5-100 ϫ 10 Ϫ9 M of scrambled or precursor miR-466g (Applied Biosystems). Lipofectamine 2000 (Invitrogen, Carlsbad, CA) was used as a transfection reagent in all experiments.…”

“…Aldosterone, by activating mineralocorticoid receptors, may similarly signal through miRNAs to control expression of genes whose products regulate ENaC activity in the CCD. Recent studies have examined aldosterone-induced changes in miRNA expression in the collecting duct; however, these studies focused on changes in miRNA expression during the late phase of aldosterone induction (12,13,20). To date, no studies have identified early-phase, aldosterone-regulated miRNAs in the CCD; nor have any studies manipulated expression of specific miRNAs in CCD cells to examine functional effects of early-phase, aldosterone-regulated miRNAs on Na ϩ transport.…”