Prdm16 deficiency leads to age-dependent cardiac hypertrophy, adverse remodeling, mitochondrial dysfunction, and heart failure

Hypertrophic cardiomyopathy (HCM) is one of the most frequent inherited heart condition and a well-established risk factor for cardiovascular mortality worldwide. Although hypertrophy is traditionally regarded as an adaptive response to increased workload caused by physiological or pathological stress, prolonged hypertrophy can lead to heart failure characterized by impaired systolic function, increased apoptosis, fibrosis, ventricular dilation, and impaired metabolic substrate flexibility. While the key regulators for cardiac hypertrophy are well studied, the role of Prdm16 in this process remains poorly understood. In the present study, we demonstrate that Prdm16 is dispensable for cardiac development. However, it is required in the adult heart to preserve mitochondrial function and inhibit hypertrophy with advanced age. Cardiac-specific deletion of Prdm16 results in cardiac hypertrophy, excessive ventricular fibrosis, mitochondrial dysfunction, and impaired metabolic flexibility, leading to heart failure. We demonstrate that Prdm16 and euchromatic histone-lysine N- methyltransferase factors (Ehmts) act together to reduce the expression of fetal genes reactivated in pathological hypertrophy by inhibiting the functions of pro- hypertrophic transcription factor Myc. Although young Prdm16 knockout mice show normal cardiac function, they are predisposed to develop heart failure in response to metabolic stress. Collectively, our results demonstrate that Prdm16 protects the heart against age-dependent cardiac hypertrophy, fibrosis, mitochondrial dysfunction, adverse metabolic remodeling, and heart failure.