NO triggers RGS4 degradation to coordinate angiogenesis and cardiomyocyte growth

J Clin Invest. 2013 Apr;123(4):1718-31. doi: 10.1172/JCI65112.

Abstract

Myocardial hypertrophy is an adaptation to increased hemodynamic demands. An increase in heart tissue must be matched by a corresponding expansion of the coronary vasculature to maintain and adequate supply of oxygen and nutrients for the heart. The physiological mechanisms that underlie the coordination of angiogenesis and cardiomyocyte growth are unknown. We report that induction of myocardial angiogenesis promotes cardiomyocyte growth and cardiac hypertrophy through a novel NO-dependent mechanism. We used transgenic, conditional overexpression of placental growth factor (PlGF) in murine cardiac tissues to stimulate myocardial angiogenesis and increase endothelial-derived NO release. NO production, in turn, induced myocardial hypertrophy by promoting proteasomal degradation of regulator of G protein signaling type 4 (RGS4), thus relieving the repression of the Gβγ/PI3Kγ/AKT/mTORC1 pathway that stimulates cardiomyocyte growth. This hypertrophic response was prevented by concomitant transgenic expression of RGS4 in cardiomyocytes. NOS inhibitor L-NAME also significantly attenuated RGS4 degradation, and reduced activation of AKT/mTORC1 signaling and induction of myocardial hypertrophy in PlGF transgenic mice, while conditional cardiac-specific PlGF expression in eNOS knockout mice did not induce myocardial hypertrophy. These findings describe a novel NO/RGS4/Gβγ/PI3Kγ/AKT mechanism that couples cardiac vessel growth with myocyte growth and heart size.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Biological
  • Animals
  • Cell Enlargement*
  • Cells, Cultured
  • Coronary Vessels / physiology
  • Endothelium, Vascular / metabolism
  • Endothelium, Vascular / physiology
  • Heart Ventricles / cytology
  • Heart Ventricles / metabolism
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Multiprotein Complexes
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / physiology*
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Neovascularization, Physiologic*
  • Nitric Oxide / physiology*
  • Nitric Oxide Synthase / antagonists & inhibitors
  • Nitric Oxide Synthase / metabolism
  • Placenta Growth Factor
  • Pregnancy Proteins / physiology
  • Proteins / metabolism
  • Proteolysis
  • Proto-Oncogene Proteins c-akt / metabolism
  • RGS Proteins / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • TOR Serine-Threonine Kinases

Substances

  • Multiprotein Complexes
  • Pgf protein, mouse
  • Pgf protein, rat
  • Pregnancy Proteins
  • Proteins
  • RGS Proteins
  • Placenta Growth Factor
  • RGS4 protein
  • Nitric Oxide
  • Nitric Oxide Synthase
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 1
  • Proto-Oncogene Proteins c-akt
  • NG-Nitroarginine Methyl Ester