Aldosterone increases oxidant stress to impair guanylyl cyclase activity by cysteinyl thiol oxidation in vascular smooth muscle cells.

Published

Journal Article

Hyperaldosteronism is associated with impaired endothelium-dependent vascular reactivity owing to increased reactive oxygen species and decreased bioavailable nitric oxide (NO(.)); however, the effects of aldosterone on vasodilatory signaling pathways in vascular smooth muscle cells (VSMC) remain unknown. Soluble guanylyl cyclase (GC) is a heterodimer that is activated by NO(.) to convert cytosolic GTP to cGMP, a second messenger required for normal VSMC relaxation. Here, we show that aldosterone (10(-9)-10(-7) mol/liter) diminishes GC activity by activating NADPH oxidase in bovine aortic VSMC to increase reactive oxygen species levels and induce oxidative posttranslational modification(s) of Cys-122, a beta(1)-subunit cysteinyl residue demonstrated previously to modulate NO(.) sensing by GC. In VSMC treated with aldosterone, Western immunoblotting detected evidence of GC beta(1)-subunit disulfide bonding, whereas mass spectrometry analysis of a homologous peptide containing the Cys-122-bearing sequence exposed to conditions of increased oxidant stress confirmed cysteinyl sulfinic acid (m/z 435), sulfonic acid (m/z 443), and disulfide (m/z 836) bond formation. The functional effect of these modifications was examined by transfecting COS-7 cells with wild-type GC or mutant GC containing an alanine substitution at Cys-122 (C122A). Exposure to aldosterone or hydrogen peroxide (H(2)O(2)) significantly decreased cGMP levels in cells expressing wild-type GC. In contrast, aldosterone or H(2)O(2) did not influence cGMP levels in cells expressing the mutant C122A GC, confirming that oxidative modification of Cys-122 specifically impairs GC activity. These findings demonstrate that pathophysiologically relevant concentrations of aldosterone increase oxidant stress to convert GC to an NO(.)-insensitive state, resulting in disruption of normal vasodilatory signaling pathways in VSMC.

Full Text

Duke Authors

Cited Authors

  • Maron, BA; Zhang, Y-Y; Handy, DE; Beuve, A; Tang, S-S; Loscalzo, J; Leopold, JA

Published Date

  • March 20, 2009

Published In

Volume / Issue

  • 284 / 12

Start / End Page

  • 7665 - 7672

PubMed ID

  • 19141618

Pubmed Central ID

  • 19141618

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M809460200

Language

  • eng

Conference Location

  • United States