Clusterin is a secretory glycoprotein, which is highly up-regulated in a variety of normal and injury tissues undergoing apoptosis including infarct region of the myocardium. Here, we report that clusterin protects H9c2 cardiomyocytes from H2O2-induced apoptosis by triggering the activation of Akt and GSK-3beta. Treatment with H2O2 induces apoptosis of H9c2 cells by promoting caspase cleavage and cytochrome c release from mitochondria. However, co-treatment with clusterin reverses the induction of apoptotic signaling by H2O2, thereby recovers cell viability. The protective effect of clusterin on H2O2-induced apoptosis is impaired by PI3K inhibitor LY294002, which effectively suppresses clusterin-induced activation of Akt and GSK-3beta. In addition, the protective effect of clusterin is independednt on its receptor megalin, because inhibition of megalin has no effect on clusturin-mediated Akt/GSK-3beta phosphoylation and H9c2 cell viability. Collectively, these results suggest that clusterin has a role protecting cardiomyocytes from oxidative stress and the Akt/GSK-3beta signaling mediates anti-apoptotic effect of clusterin.
Animals ; *Apoptosis ; Blotting, Western ; Caspase 3/metabolism ; Caspase 9/metabolism ; Cell Line ; Chromones/pharmacology ; Clusterin/metabolism/*pharmacology ; Glycogen Synthase Kinase 3/metabolism ; Humans ; Hydrogen Peroxide/pharmacology ; LDL-Receptor Related Protein 2/metabolism ; Morpholines/pharmacology ; Myocytes, Cardiac/*metabolism ; *Oxidative Stress ; Phosphatidylinositol 3-Kinases/metabolism ; Proto-Oncogene Proteins c-akt/metabolism ; RNA, Small Interfering ; Rats ; Reactive Oxygen Species/pharmacology ; Reverse Transcriptase Polymerase Chain Reaction ; *Signal Transduction/drug effects