Activation of GSK3β participates hypoxia-induced cardiomyocyte apoptosis

Objective To explore the effect of hypoxia on activation of GSK3β coupled signal transduction pathway in cardiomyocytes. Methods After exposed to hypoxia for 0, 3, 6, 12, 24 h, the cell apoptosis and viability were determined with Hoechst 33342 staining and MTT respectively. The expressions of GSK3β, caspases-9, -3 mRNA and phosphorylation of GSK3β protein in primary culture of cardiomyocytes were determined by RT-PCR and Western blotting respectively. The changes of caspase-9 enzyme activity were assessed via a colorimetric assay. Results Typical cell apoptosis was induced in cardiomyocytes and cell viability significantly decreased after 24-hour hypoxia. Hypoxia for 3 to 24 h induced the increase of GSK3β mRNA expression. The levels of phosphorylated form of GSK3β obviously decreased after hypoxia for 6 to 24 h. Caspase-9 mRNA expression increased after hypoxia for 3 to 24 h and caspase-3 mRNA expression increased after hypoxia for 12 or 24 h. In consistent with the expression of caspase-9 mRNA, caspase-9 activity was markedly elevated after hypoxia for 3 to 24 h. Conclusion Hypoxia could induce cardiomyocyte apoptosis. Hypoxia can activate GSK3β and caspase-9, -3. These results demonstrate the activation of GSK3β signal transduction pathway participates hypoxia-induced cardiomyocyte apoptosis.