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

Bradley A. Maron, Ying Yi Zhang, Diane E. Handy, Annie Beuve, Shiow Shih Tang, Joseph Loscalzo, Jane A. Leopold

Research output: Contribution to journalArticlepeer-review

79 Scopus citations

Abstract

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 β1-subunit cysteinyl residue demonstrated previously to modulate NO sensing by GC. In VSMC treated with aldosterone, Western immunoblotting detected evidence of GC β1-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 (H2O2) significantly decreased cGMP levels in cells expressing wild-type GC. In contrast, aldosterone or H2O2 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.

Original languageEnglish (US)
Pages (from-to)7665-7672
Number of pages8
JournalJournal of Biological Chemistry
Volume284
Issue number12
DOIs
StatePublished - Mar 20 2009

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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