title: Aldosterone stimulates vascular smooth muscle cell proliferation via big mitogen-activated protein kinase 1 activation.
abstract: The nongenomic effects of aldosterone have been implicated in the pathogenesis of various cardiovascular diseases. Aldosterone-induced nongenomic effects are attributable in part to the activation of extracellular signal-regulated kinase 1/2 (ERK1/2), a classical mitogen-activated protein (MAP) kinase. Big MAP kinase 1 (BMK1), a newly identified MAP kinase, has been shown to be involved in cell proliferation, differentiation, and survival. We examined whether aldosterone stimulates BMK1-mediated proliferation of cultured rat aortic smooth muscle cells (RASMCs). Mineralocorticoid receptor (MR) expression and localization were evaluated by Western blotting analysis and fluorolabeling methods. ERK1/2 and BMK1 activities were measured by Western blotting analysis with the respective phosphospecific antibodies. Cell proliferation was determined by Alamar Blue colorimetric assay. Aldosterone (0.1 to 100 nmol/L) dose-dependently activated BMK1 in RASMCs, with a peak at 30 minutes. To clarify whether aldosterone-induced BMK1 activation is an MR-mediated phenomenon, we examined the effect of eplerenone, a selective MR antagonist, on aldosterone-induced BMK1 activation. Eplerenone (0.1 to 10 micromol/L) dose-dependently inhibited aldosterone-induced BMK1 activation in RASMCs. Aldosterone also stimulated RASMC proliferation, which was inhibited by eplerenone. Aldosterone-mediated phenomena were concluded to be attributable to a nongenomic effect because cycloheximide failed to inhibit aldosterone-induced BMK1 activation. Transfection of dominant-negative MAP kinase/ERK kinase 5 (MEK5), which is an upstream regulator of BMK1, partially inhibited aldosterone-induced RASMC proliferation, which was almost completely inhibited by MEK inhibitor PD98059. In addition to the classical steroid activity, rapid nongenomic effects induced by aldosterone may represent an alternative etiology for vascular diseases such as hypertension.
authors.affiliation: Department of Pharmacology, University of Tokushima Graduate School of Medicine, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ishizawa
authors.forename: Yuki
authors.initials: Y
authors.lastname: Izawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.forename: Chieko
authors.initials: C
authors.lastname: Miki
authors.forename: Kayoko
authors.initials: K
authors.lastname: Miyata
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Fujita
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Kanematsu
authors.forename: Koichiro
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tamaki
authors.forename: Akira
authors.initials: A
authors.lastname: Nishiyama
authors.forename: Masanori
authors.initials: M
authors.lastname: Yoshizumi
mesh_terms: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D000077545:Eplerenone; D005419:Flavonoids / Q000494:pharmacology; D005799:Genes, Dominant; D048671:MAP Kinase Kinase 5 / Q000235:genetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D048054:Mitogen-Activated Protein Kinase 7 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D018161:Receptors, Mineralocorticoid / Q000378:metabolism; D013148:Spironolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D014162:Transfection
chemical_list: D005419:Flavonoids; D011500:Protein Synthesis Inhibitors; D018161:Receptors, Mineralocorticoid; D013148:Spironolactone; D000450:Aldosterone; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D000077545:Eplerenone; D003513:Cycloheximide; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048054:Mitogen-Activated Protein Kinase 7; D048671:MAP Kinase Kinase 5; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one