Abstract 12312: UBC9 Protects Against Cardiac Hypertrophy and Heart Failure via Regulating FOXO3-LMCD1 Pathway

Abstract

Introduction: Pathological cardiac hypertrophy is a major risk factor for heart failure (HF) and a leading cause of morbidity and mortality worldwide. However, the molecular mechanisms underlying pathological cardiac hypertrophy remain unclear. Hypothesis: In the present study, we investigated the possible underlying effects of UBC9 on cardiac hypertrophy and heart failure. Methods: UBC9 was upregulated in samples of human hypertrophic hearts compared to normal controls using RNA sequencing analysis from the Gene Expression Omnibus (GEO, https://www.ncbi.nlm.nih.gov/geo). Real-time polymerase chain reaction (RT-PCR) and western blotting were used to analyze the expression of UBC9 in samples of human hypertrophic hearts and normal controls. Mice with cardiac-specific over-expression and low-expression of UBC9 by intravenous injection of adeno-associated virus 9 (AAV9)-encoding UBC9 under the control of cardiac troponin T (cTnT) promoter were subjected to transverse aortic construction (TAC). Co-immunoprecipitation assays were performed to determine the mechanism by which UBC9 regulates the expression of forkhead box O3 (FOXO3). Results: UBC9 expression increased in the hearts of patients with hypertrophic cardiomyopathy (HCM) and pressure overload-induced mice, as well as in the Neonatal Mouse Cardiomyocytes (NMCMs) treated with phenylephrine (PE). Cardiac cell-specific UBC9 over-expression alleviates cardiac hypertrophy and dysfunction. Cardiac cell-specific UBC9 knockout aggravates cardiac hypertrophy and heart failure. Mechanistically, UBC9 inhibits LIM and cysteine-rich domain 1 (LMCD1) expression by directly binding to forkhead box O3 (FOXO3), a transcription factor of LMCD1, and promoting FOXO3 dephosphorylation and nuclear translocation, independent of SUMOylation. Conclusions: This study provides a new insight that UBC9, as a potential intervention target in cardiac hypertrophy and HF, may contribute to exploring effective therapeutic strategies for pathological cardiac hypertrophy treatment.