Protective role of the deSUMOylating enzyme SENP3 in myocardial ischemia-reperfusion injury

Interruption of blood supply to the heart is a leading cause of death and disability. However, the molecular events that occur during heart ischemia, and how these changes prime consequent cell death upon reperfusion, are poorly understood. Protein SUMOylation is a post-translational modification that has been strongly implicated in the protection of cells against a variety of stressors, including ischemia-reperfusion. In particular, the SUMO2/3-specific protease SENP3 has emerged as an important determinant of cell survival after ischemic infarct. Here, we used the Langendorff perfusion model to examine changes in the levels and localisation of SUMOylated target proteins and SENP3 in whole heart. We observed a 50% loss of SENP3 from the cytosolic fraction of hearts after preconditioning, a 90% loss after ischemia and an 80% loss after ischemia-reperfusion. To examine these effects further, we performed ischemia and ischemia-reperfusion experiments in the cardiomyocyte H9C2 cell line. Similar to whole hearts, ischemia induced a decrease in cytosolic SENP3. Furthermore, shRNA-mediated knockdown of SENP3 led to an increase in the rate of cell death upon reperfusion. Together, our results indicate that cardiac ischemia dramatically alter levels of SENP3 and suggest that this may a mechanism to promote cell survival after ischemia-reperfusion in heart.