Disruption of phospholipase Cgamma1 signalling attenuates cardiac tumor necrosis factor-alpha expression and improves myocardial function during endotoxemia

Cardiovasc Res. 2008 Apr 1;78(1):90-7. doi: 10.1093/cvr/cvm100. Epub 2007 Dec 12.

Abstract

Aims: Lipopolysaccharide (LPS) induces tumor necrosis factor-alpha (TNF-alpha) expression in cardiomyocytes, which contributes to myocardial dysfunction during sepsis. The purpose of this study was to investigate the role of phosphatidylinositol (PI) phospholipase Cgamma1 (PLCgamma1) in cardiac TNF-alpha expression, and myocardial dysfunction during endotoxemia.

Methods and results: In cultured mouse neonatal cardiomyocytes, LPS increased PLCgamma1 phosphorylation. Knockdown of PLCgamma1 with specific siRNA or inhibition of PLCgamma1 with U73122 attenuated TNF-alpha expression induced by LPS. This action of PLCgamma1 was mediated through inositol-1,4,5-trisphosphate (IP3)/IP3 receptor (IP3R) pathways since blocking either IP3 or IP3R decreased LPS-induced TNF-alpha expression. In contrast, neither diacylglycerol agonist nor antagonist had any evident effect on LPS-induced TNF-alpha expression in cardiomyocytes. To investigate the role of PLCgamma1 in endotoxemia in vivo, wild-type and heterozygous PLCgamma1 knockout (PLCgamma1(+/-)) mice were pre-treated with either U73122, or its inactive analog U73343, or vehicle for 15 min, followed by LPS for 4 h. Inhibition of PLCgamma1 by U73122 or by heterozygous deletion of the PLCgamma1 gene decreased cardiac TNF-alpha expression. More importantly, LPS-induced myocardial dysfunction was also attenuated in PLCgamma1(+/-) mice or by U73122 treatment.

Conclusion: PLCgamma1 signalling induces cardiac TNF-alpha expression and myocardial dysfunction during LPS stimulation. The action of PLCgamma1 on TNF-alpha expression is mediated through IP3/IP3R pathways. The present results suggest that PLCgamma1 may be a potential therapeutic target for myocardial dysfunction in sepsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Cardiomyopathies / enzymology
  • Cardiomyopathies / etiology*
  • Cardiomyopathies / physiopathology
  • Cells, Cultured
  • Diglycerides / metabolism
  • Disease Models, Animal
  • Endotoxemia / chemically induced
  • Endotoxemia / complications
  • Endotoxemia / enzymology*
  • Endotoxemia / physiopathology
  • Estrenes / pharmacology
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Inositol 1,4,5-Trisphosphate Receptors / metabolism
  • Lipopolysaccharides
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myocardial Contraction* / drug effects
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / enzymology*
  • Phosphodiesterase Inhibitors / pharmacology
  • Phospholipase C gamma / antagonists & inhibitors
  • Phospholipase C gamma / genetics
  • Phospholipase C gamma / metabolism*
  • Phosphorylation
  • Pyrrolidinones / pharmacology
  • RNA Interference
  • Signal Transduction* / drug effects
  • Transfection
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • Diglycerides
  • Estrenes
  • Inositol 1,4,5-Trisphosphate Receptors
  • Lipopolysaccharides
  • Phosphodiesterase Inhibitors
  • Pyrrolidinones
  • Tumor Necrosis Factor-alpha
  • 1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
  • Inositol 1,4,5-Trisphosphate
  • Phospholipase C gamma
  • Plcg1 protein, mouse