USP11 alleviates pathological cardiac hypertrophy via stabilizing SIRT6

Pathological cardiac hypertrophy is a key precursor to heart failure. Protein ubiquitination and deubiquitination are crucial mechanisms controlling cardiomyocyte signaling homeostasis. USP11, a ubiquitin-specific protease, has been implicated in multiple cellular regulatory processes, but its cardiac function remains unknown. Here, we investigated whether USP11 modulates cardiac hypertrophy and explored its downstream molecular mechanisms. USP11 expression was detected in hearts from mice subjected to transverse aortic constriction (TAC) and in phenylephrine (PE)-stimulated cardiomyocytes. Cardiomyocyte-specific overexpression of USP11 was achieved using AAV9-cTnT-USP11. The effects of USP11 on cardiac remodeling and function were evaluated by echocardiography, histology, and molecular analyses. Neonatal rat ventricular cardiomyocytes (NRVMs) were used for in vitro assays. Co-immunoprecipitation (co-IP), mass spectrometry, and ubiquitination assays were performed to explore the interaction between USP11 and SIRT6 and its mechanistic consequences. USP11 expression was markedly decreased in hypertrophic mouse hearts and PE-treated NRVMs. Cardiomyocyte-specific overexpression of USP11 significantly alleviated TAC-induced cardiac hypertrophy and fibrosis, improving left ventricular function. In NRVMs, USP11 overexpression mitigated PE-induced cardiomyocyte hypertrophy, whereas USP11 silencing aggravated hypertrophy. Mechanistically, USP11 directly bound to and stabilized SIRT6 by removing its K48-linked ubiquitin chains, thereby preventing its proteasomal degradation. USP11 attenuated the activation of the IGF2-AKT signaling pathway by stabilizing SIRT6, while the absence of USP11 had the opposite effect. Mutation of the catalytic site of USP11 abolished both its effect on SIRT6 stabilization and its ability to attenuate cardiac hypertrophy. Furthermore, reintroduction of SIRT6 rescued the pro-hypertrophic effects of USP11 deficiency. USP11 acts as a protective deubiquitinase in pathological cardiac hypertrophy by stabilizing SIRT6 and inhibiting the SIRT6-regulated IGF2-AKT signaling axis. Targeting the USP11-SIRT6 pathway may represents a potential therapeutic target for preventing maladaptive cardiac remodeling and heart failure.