USP10 protects against pressure overload-induced mitochondrial morphofunctional defects and pathological cardiac hypertrophy through stabilizing cytoplasmic Mfn2

Increasing evidence has implicated the important role of mitochondrial morphofunctional defects in pathological myocardial hypertrophy and heart failure. Deubiquitinating enzymes (DUBs) are involved in protein stability maintenance and regulate multiple cellular processes, while it remains largely unclear whether DUBs participate in the maintenance of mitochondrial morphofunction. The aim of this study was to investigate the possible link between DUBs and abnormal mitochondrial morphofunction in pressure overload-induced pathological cardiac hypertrophy and explore the underlying molecular mechanism. RNA sequencing results showed that ubiquitin-mediated proteolysis was markedly enriched in pressure overload-induced hypertrophied and failing myocardium, and USP10 was identified as the most significantly downregulated gene among them and correlated with heart failure severity in human heart samples. Restoration of USP10 mitigates cardiac hypertrophy and dysfunction as well as abnormal mitochondrial morphofunction in vitro and in vivo. Immunoprecipitation and mass spectrometry analysis mechanistically revealed that USP10 directly interacted with Mfn2 (a mitochondrial outer membrane protein). Interestingly, the interaction between Mfn2 and USP10 occurred in cytoplasm but not on mitochondria. His-679 in the UCH domain of USP10 exerted deubiquitination to maintain the stability of the Mfn2 by removing the K11/K48 ubiquitin chain and preventing proteasomal pathway degradation, thereby maintaining mitochondrial function and homeostasis. Knockdown or knockout of Mfn2 largely eliminated the cardioprotection of USP10. Additionally, reduced USP10 expression in hypertrophied myocardium was induced by impaired translation of Yy1. Together, our findings provide a USP10-modulated mitochondrial homeostasis mechanism that enhances the stability of cytoplasmic Mfn2 before its translocation to mitochondria. USP10 may represent a novel therapeutic target for combating pressure overstress-induced cardiac hypertrophy and heart failure.