USP36 mediates Doxorubicin-induced cardiomyopathy through inhibiting ubiquitination and degradation of PARP1

Doxorubicin (Dox) is a powerful antineoplastic agent, but its usage is limited by the severe cardiotoxicity referred to as Dox-induced cardiomyopathy (DIC). However, the molecular mechanism underlying this cardiotoxicity is yet to be fully elucidated. Here, our current study sought to determine the role of ubiquitin-specific protease 36 (USP36), a nucleolar deubiquitinating enzyme (DUB), in the progress of DIC and its mechanism. We identified an increased expression of USP36 both in neonatal rat cardiomyocytes and H9C2 cells exposed to Dox, and USP36 silencing significantly ameliorated Dox-induced oxidative stress injury and apoptosis in vitro. Mechanistically, USP36 upregulation was observed to positively correlate with PARP1 expression, and its knockdown resulted in reduction of PARP1 levels. Further investigation showed that USP36 could bind to and mediate the deubiquitination of PARP1 and increase its protein stability in cardiomyocytes upon Dox exposure. Moreover, overexpression of wild-type (WT) USP36 plasmid, but not its catalytic-inactive mutant (C131A), stabilizes PARP1 in HEK293T cells. Herein, we also established DIC model in mice and observed a significant upregulation of USP36 in the heart. Cardiac knockdown of USP36 in mice by a type 9 recombinant adeno-associated virus (rAAV9)-shUSP36 significantly preserved cardiac function after Dox treatment and protected against Dox-induced in terms of structural changes within the myocardium. Collectively, these findings indicate that Dox promotes DIC progression by activating USP36-mediated PARP1 deubiquitination. This novel USP36/PARP1 axis may play an important regulatory mechanism in the pathogenesis of DIC.