Abstract 13245: Senp8 Regulates Deneddylation and Protects Cardiomyocytes against Simulated Ischemia/reperfusion Injury
Posttranslational modification with small ubiquitin-like protein NEDD8 (neddylation) regulates numerous cellular and developmental processes. Neddylation is dynamic and counteracted by NEDD8-specific protease-mediated deconjugation (deneddylation). The pathophysiological role of neddylation/deneddylation in the heart remains unclear. We have previously revealed that cardiac-specific inactivation of NEDD8 protease COP9 signalosome (CSN) impaired both proteasomal and autophagic proteolysis, leading to lethal dilated cardiomyopathy in mice. Here we report that the cysteine protease SENP8 is essential to deneddylation and the survival of cardiomyocytes. SENP8 depletion by siRNA accumulates neddylated proteins in cardiomyocytes and reduces cell viability. Overexpression (o/e) of SENP8 does not alter the abundance of neddylated proteins at basal condition, however, diminishes proteasome inhibition (PI)-induced neddylation. The deneddylation activity of SENP8 requires its cysteine163, whose mutation to alanine fails to abolish PI-induced neddylation. Moreover, depletion of CSN subunit 8 (CSN8) accumulates neddylated proteins, which is attenuated by SENP8 o/e, indicating the coordination of SENP8 and CSN in deneddylation. Furthermore, we show simulated ischemia reduces low-molecular-weight neddylated protein but increases the high-molecular-weight ones in cultured cardiomyocytes. The altered neddylation profile is reversed at the reperfusion stage. SENP8 o/e attenuates simulated ischemia/reperfusion (sI/R)-induced neddylation and apoptosis, whereas SENP8 depletion does the opposite. Inhibition of neddylation with a specific NEDD8 activating enzyme (NAE) inhibitor MLN4924 also abrogates sI/R-induced apoptosis. In mouse hearts, neddylated proteins are accumulated in the infarcted area but not in border zone or remote area. Together, our findings suggest that (1) SENP8 is indispensible to deneddylation, (2) sI/R disrupts the dynamic neddylation and deneddylation, and (3) SENP8 protects cardiomyocyte against sI/R injury, likely by fine-tuning neddylation. Therefore, targeting neddylation/deneddylation may be a novel therapeutic avenue to the prevention and treatment of ischemic cardiomyopathy.
- © 2013 by American Heart Association, Inc.