A Splicing-Independent Function of RBM10 Controls Specific 3′ UTR Processing to Regulate Cardiac Hypertrophy

RNA binding motif protein 10 (RBM10) is a regulator of alternative splicing in apoptosis and inflammation. We discovered a splicing-independent function of RBM10 critical for the regulation of heart failure (HF). RBM10 is enriched in the heart and associates with Star-PAP (TUT1) to control the expression and 3' zend processing of cardiac mRNAs. The RBM10 RRM2 domain binds the Star-PAP catalytic domain, which directs Star-PAP activity toward polyadenylation. RBM10 binds the pre-mRNA UTR, assembles the Star-PAP complex, and guides this complex specifically to mRNAs encoding anti-hypertrophy regulators. Accordingly, we tested cellular hypertrophy in rat cardiomyoblasts and cardiac hypertrophy (CH) and the subsequent progression to HF in Wistar rat hearts. We demonstrated downregulation of RBM10 during CH and HF. Ectopic re-expression of RBM10 rescued cardiomyocyte hypertrophy. RBM10 depletion evoked a hypertrophic response in H9c2 cells. Our results establish an anti-hypertrophy-mechanism mediated by RBM10 in the heart that is directly linked to HF.