Regulation of Na-K-ATPase gene expression by aldosterone in vascular smooth muscle cells.
Na-K-adenosinetriphosphatase (ATPase) activity profoundly influences vascular cell excitability, contractility, and volume regulation. The recent finding of mineralocorticoid hormone receptors in vascular tissue suggests the possibility that Na-K-ATPase gene expression in vascular tissue is regulated by the mineralocorticoid aldosterone. In this study, we investigated Na-K-ATPase gene expression by aldosterone in cultured rat vascular smooth muscle cells (VSMC). Na-K-ATPase alpha 1- and beta 1-isoform mRNAs, but not alpha 2- and alpha 3-isoform mRNAs, were expressed in cultured rat VSMC. Aldosterone caused a 2.3-fold increase in the alpha 1 mRNA and a 4.7-fold increase in the beta 1 mRNA accumulation with peak elevations at 24 and 6 h, respectively. Aldosterone induced the alpha 1 mRNA expression at physiological concentrations (half-maximum effective concentration = 2-3 nM), consistent with the binding of aldosterone to mineralocorticoid hormone receptors. The augmented alpha 1 mRNA expression by aldosterone was associated with a twofold increase in the alpha 1-subunit protein accumulation. Pretreatment of VSMC with cycloheximide caused a 10-fold increase in the alpha 1 mRNA expression, and the aldosterone-mediated alpha 1 mRNA accumulation was not observed in the presence of cycloheximide. Transfection experiments with the luciferase reporter gene revealed that aldosterone response sequences are located within the 5'-flanking regions of the alpha 1-isoform gene. These data demonstrate that the mineralocorticoid aldosterone directly stimulates Na-K-ATPase gene expression and protein accumulation in VSMC.
Oguchi
A
A
Department of Cardiology, Jichi Medical School, Tochigi, Japan.
Ikeda
U
U
Kanbe
T
T
Tsuruya
Y
Y
Yamamoto
K
K
Kawakami
K
K
Medford
R M
RM
Shimada
K
K
D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D007527:Isoenzymes / Q000235:genetics; D008156:Luciferases / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics*; D014162:Transfection
D007527:Isoenzymes; D012333:RNA, Messenger; D000450:Aldosterone; D003513:Cycloheximide; D008156:Luciferases; D000254:Sodium-Potassium-Exchanging ATPase