G alpha(i) and G alpha(o) are target proteins of reactive oxygen species.
Reactive oxygen species (ROS) have been identified as central mediators in certain signalling events. In the heart, ROS have important functions in ischaemia/reperfusion-induced cardiac injury and in cytokine-stimulated hypertrophy. Extracellular signal-regulated kinase (ERK) is one of the ROS-responsive serine/threonine kinases. Previous studies showed that tyrosine kinases and small G proteins are involved in the activation of ERK by ROS; however, the initial target protein of ROS that leads to ERK activation remains unknown. Here we show that inhibition of the betagamma-subunit of G protein (G betagamma) attenuates hydrogen peroxide (H2O2)-induced ERK activation in rat neonatal cardiomyocytes. The G betagamma-responsive ERK activation induced by H2O2 is independent of ligands binding to Gi-coupled receptors, but requires phosphatidylinositol-3-kinase and Src activation. In in vitro studies, however, treatment with H2O2 increases [35S]GTP-gammaS binding to cardiac membranes and directly activates purified heterotrimeric Gi and Go but not Gs. Analysis using heterotrimeric Go and its individual subunits indicates that H2O2 modifies G alpha(o) but not G betagamma, which leads to subunit dissociation. We conclude that G alpha(i) and G alpha(o) are critical targets of oxidative stress for activation of ERK.
Nishida
M
M
Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Science, University of Tokyo, Japan.
Maruyama
Y
Y
Tanaka
R
R
Kontani
K
K
Nagao
T
T
Kurose
H
H
D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D018384:Oxidative Stress; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D051552:beta-Adrenergic Receptor Kinases
D017382:Reactive Oxygen Species; D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006861:Hydrogen Peroxide; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins