FTY720 attenuates hypoxia-reoxygenation-induced apoptosis in cardiomyocytes

FTY720, sphingosine 1 phosphate (S1P) receptor agonist, is a potent immunosuppressive agent. Numerous studies have documented a relationship between S1P and cardioprotection. We therefore hypothesized that a S1P analogue FTY720 would attenuate hypoxia/reoxygenation (H/R) induced cadiomyocyte apoptosis. H9C2 cardiomyocytes were employed to establish an in vitro model of H/R. Cells were treated or not with different doses of FTY720. Cell viability was measured by flow cytometry and TUNEL staining. Western blot was used to analyze downstream signaling pathway. We observed that FTY720 inhibits the expression of cleaved caspase-3 and activates both AKT and ERK1/2 pathways. AKT pathway can be blocked by MEK kinase inhibitor PD98059. ERK1/2 pathway can be blocked by the phosphoinositide-3 kinase inhibitor wortmannin. AKT and ERK1/2 activation can also be inhibited by S1P1/3 receptor antagonist VPC23019, Gi antagonist PTX. The protein levels of TNF-α and IL1ß were upregulated during hypoxia/reoxygenation and were attenuated by FTY720. We conclude that FTY720, via its cargo of S1P, can protect cardiomyocytes against hypoxia/reoxygenation injury. This effect is achieved by inhibiting caspase-3 expression, inflammatory cytokine levels and activating AKT and ERK1/2 signaling pathways. The prosurvival signal activation is dependent on S1P1, 3 subtype receptors and Gi protein.