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Glucocorticoid-related signaling effects in vascular smooth muscle cells

Authors

  • G.A. Molnar
  • C. Lindschau
  • G. Dubrovska
  • P.R. Mertens
  • T. Kirsch
  • M. Quinkler
  • M. Gollasch
  • S. Wresche
  • F.C. Luft
  • D.N. Mueller
  • A. Fiebeler

Journal

  • Hypertension

Citation

  • Hypertension 51 (5): 1372-1378

Abstract

  • Mineralocorticoid receptor blockade protects from angiotensin II-induced target-organ damage. 11beta-Hydroxysteroid dehydrogenase type 2 protects the mineralocorticoid receptor from activation by glucocorticoids; however, high glucocorticoid concentrations and absent 11beta-hydroxysteroid dehydrogenase type 2 in some tissues make glucocorticoids highly relevant mineralocorticoid receptor ligands. We investigated the effects of corticosterone (10(-6) to 10(-12) mol/L) on early vascular mineralocorticoid receptor signaling by Western blotting, confocal microscopy, and myography. Corticosterone initiated extracellular signal-regulated kinase 1/2 phosphorylation in rat vascular smooth muscle cells at >/=10(-11) mol/L doses. Protein synthesis inhibitors had no effect, indicating a nongenomic action. Corticosterone also stimulated c-Jun N-terminal kinase, p38, Src, and Akt phosphorylation at 15 minutes and enhanced angiotensin II-induced signaling at 5 minutes. A specific epidermal growth factor receptor blocker, AG1478, as well as the Src inhibitor PP2, markedly reduced corticosterone-induced extracellular signal-regulated kinase 1/2 phosphorylation, as did preincubation of cells with the mineralocorticoid receptor antagonist spironolactone. Silencing mineralocorticoid receptor with small interfering RNA abolished corticosterone-induced effects. Corticosterone (10(-9) mol/L) enhanced phenylephrine-induced contraction of intact aortic rings. These effects were dependent on the intact endothelium, mineralocorticoid receptor, and mitogen-activated protein kinase kinase 1/extracellular signal-regulated kinase signaling. We conclude that corticosterone induces rapid mineralocorticoid receptor signaling in vascular smooth muscle cells that involves mitogen-activated protein kinase kinase/extracellular signal-regulated kinase-dependent pathways. These new mineralocorticoid receptor-dependent signaling pathways suggest that glucocorticoids may contribute to vascular disease via mineralocorticoid receptor signaling, independent of circulating aldosterone.


DOI

doi:10.1161/HYPERTENSIONAHA.107.105718