Regulator of G-protein signaling 5 protects cardiomyocytes against apoptosis during in vitro cardiac ischemia-reperfusion in mice by inhibiting both JNK1/2 and P38 signaling pathways

Ischemic heart disease is one of the most common diseases in modern society. Ischemic myocardium can be salvaged by vascular recanalization therapy, but its benefit is attenuated by injury that can occur during reperfusion. And apoptotic cell death plays an important part in myocardial ischemia-reperfusion (IR) injury. Regulator of G-protein signaling 5 (RGS5), highly expressed in different cell types of the human adult heart, is a guanosine triphosphatase-activating protein to inhibit many signaling pathways such as c-Jun NH2-terminal kinase 1/2 (JNK1/2) and p38 which promote cardiac IR-induced apoptosis. However the role of RGS5 in cardiac IR-induced apoptosis remains unclear. An in vitro IR model was applied to the isolated hearts of wild type mice (WT), RGS5-transgenic mice (TG), and RGS5-knockout mice (KO). Our results revealed that compared with either WT or KO mice, TG mice showed inhibition of cardiomyocyte apoptosis as indicated by a greater increase of B cell lymphoma/lewkmia-2 (Bcl-2), and an obvious reduction in the positive expression of the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), Bcl-2 Associated X protein (Bax), and active caspase-3. Moreover, the inhibition of both JNK1/2 and p38 signaling markedly reversed IR-induced cardiomyocyte apoptosis in RGS5-KO mice. These studies show that RGS5 protects cardiomyocytes against apoptosis during IR through inhibiting both JNK1/2 and p38 signaling pathways.