Date Published: April 11, 2019
Publisher: Public Library of Science
Author(s): Nadiia Rawlings, Laura Lee, Yasuko Nakamura, Kevin A. Wilkinson, Jeremy M. Henley, Guo-Chang Fan.
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.
Standard clinical treatment after a heart attack is to restore blood supply as soon as possible in order to limit infarct size and reduce mortality. Paradoxically, however, this can cause oxidative damage, referred to as reperfusion injury, which leads to cardiomyocyte cell death and contributes to reduced cardiac output . An important goal in the field is to identify the cellular changes that occur during ischemia and subsequent reperfusion, with a view to determining how intervening in these pathways may promote cell viability after ischemic insult.
Increased understanding of the molecular mechanisms underpinning the pathology of cardiac ischemia and reperfusion is important for the identification of novel drug targets. Here we investigated the molecular changes that occur following a short period of ischemia which can prime cells for reperfusion damage or initiate protection during the subsequent reperfusion phase. In particular, we focused on protein SUMOylation, which has been previously reported to be protective against ischemia/reperfusion damage. Using total homogenate and subcellular fractions from whole hearts subjected to Langendorff perfusion, we observed changes in levels of protein SUMO1-ylation and SUMO2/3-ylation in different subcellular fractions. Furthermore, we detected changes in SUMOylation of individual mitochondrial substrate proteins.