Role of SGK in hormonal regulation of epithelial sodium channel in A6 cells.
The purpose of this study was to examine the role of the serum- and glucocorticoid-induced kinase (SGK) in the activation of the epithelial sodium channel (ENaC) by aldosterone, arginine vasopressin (AVP), and insulin. We used a tetracycline-inducible system to control the expression of wild-type (SGK(wt)(T)), constitutively active (S425D mutation; SGK(S425D)(T)), or inactive (K130M mutation; SGK(K130M)(T)) SGK in A6 cells independently of hormonal stimulation. The effect of SGK expression on ENaC activity was monitored by measuring transepithelial amiloride-sensitive short-circuit current (I(sc)) of transfected A6 cell lines. Expression of SGK(wt)(T) or SGK(S425D)(T) and aldosterone stimulation have additive effects on I(sc). Although SGK could play some role in the aldosterone response, our results suggest that other mechanisms take place. SGK(S425D)(T) abrogates the responses to AVP and insulin; hence, in the signaling pathways of these hormones there is a shared step that is stimulated by SGK. Because AVP and insulin induce fusion of vesicles to the apical membrane, our results support the notion that SGK promotes incorporation of channels in the apical membrane.
Alvarez de la Rosa
Diego
D
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520-8026, USA.
Canessa
Cecilia M
CM
D000450:Aldosterone / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism* / Q000494:pharmacology; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002999:Clone Cells / Q000187:drug effects / Q000378:metabolism; D018076:DNA, Complementary / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D017874:Immediate-Early Proteins; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D009154:Mutation / Q000187:drug effects / Q000502:physiology; D009399:Nephrons / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013752:Tetracycline / Q000494:pharmacology; D014982:Xenopus laevis; D000099184:Serum-Glucocorticoid Regulated Kinases
D000450:Aldosterone; D001127:Arginine Vasopressin; D002352:Carrier Proteins; D018076:DNA, Complementary; D053503:Epithelial Sodium Channels; D017874:Immediate-Early Proteins; D007328:Insulin; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D012097:Repressor Proteins; D012964:Sodium; D015222:Sodium Channels; D013752:Tetracycline; D000099184:Serum-Glucocorticoid Regulated Kinases