Targeting of phospholamban by peroxynitrite decreases β-adrenergic stimulation in cardiomyocytes

Mark J. Kohr, Honglan Wang, Debra G. Wheeler, Murugesan Velayutham, Jay L. Zweier, Mark T. Ziolo

Research output: Contribution to journalArticle

Abstract

Aims: Peroxynitrite production increases during the pathogenesis of numerous cardiac disorders (e.g. heart failure). However, limited studies have investigated the mechanism through which peroxynitrite exerts anti-adrenergic effects. Thus, the purpose of this study is to investigate the contribution of phospholamban (PLB), a critical excitation-contraction coupling protein, to the peroxynitrite-induced dysfunction. Methods and results: Isolated myocytes from wild-type (WT, CF-1) and PLB knockout (PLB-/-) mice were stimulated at 1 Hz, and myocyte shortening and Ca2+ transients were simultaneously recorded. PLB phosphorylation was measured via western blot. Myocytes were superfused with isoproterenol, a β-adrenergic agonist, and SIN-1, a peroxynitrite donor. SIN-1 superfusion dramatically decreased isoproterenol-stimulated Ca2+ transients and myocyte shortening in WT myocytes. These effects were inhibited upon addition of the peroxynitrite decomposition catalyst, FeTPPS. Surprisingly, SIN-1 had no functional effect on β-adrenergic-stimulated PLB-/- myocytes. Western blot analyses revealed that SIN-1 significantly decreased isoproterenol-stimulated PLB Ser16 phosphorylation. Experiments with the protein phosphatase inhibitor, okadaic acid, alleviated the SIN-1-induced functional effects and the decrease in PLB phosphorylation. Conclusions: The peroxynitrite donor SIN-1 decreases β-adrenergic stimulation by reducing PLBSer16 phosphorylation via protein phosphatase activation. This peroxynitrite-induced decrease in PLB phosphorylation may be a key mechanism in the β-adrenergic dysfunction observed in many cardiomyopathies. Published on behalf of the European Society of Cardiology. All rights reserved.

Original languageEnglish (US)
Pages (from-to)353-361
Number of pages9
JournalCardiovascular research
Volume77
Issue number2
DOIs
StatePublished - Jan 1 2008
Externally publishedYes

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Keywords

  • Calcium (cellular)
  • E-C coupling
  • Protein Phosphatases
  • Protein Phosphorylation
  • SR Function

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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