p53-dependent mitochondrial compensation in heart failure with preserved ejection fraction

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) accounts for 50% of heart failure patients. Clinically, HFpEF prevalence show age and gender biases. Although the majority of HFpEF patients are elderly, there is an emergence of young HFpEF patients. A better understanding of the underlying pathogenic mechanism is urgently needed. Here, we aimed to determine the role of aging in the pathogenesis of HFpEF. METHODS AND RESULTS: HFpEF dietary regimen (HFD + L-NAME) was used to induce HFpEF in wildtype and telomerase RNA knockout mice (mTRG2 and mTRG3), an aging murine model. First, both male and female animals develop HFpEF equally. Second, cardiac wall thickening preceded diastolic dysfunction in all HFpEF animals. Third, accelerated HFpEF onset was observed in mTRG2 (at 6-weeks) and mTRG3 (at 4-weeks) compared to wildtype (8-weeks). Fourth, we demonstrate that mitochondrial respiration transitioned from compensatory state (normal basal yet loss of maximal respiratory capacity) to dysfunction (loss of both basal and maximal respiratory capacity) in a p53 dosage dependent manner. Last, using myocardial-specific p53 knockout animals, we demonstrate that p53 is necessary for the development of HFpEF. CONCLUSIONS: Here we demonstrate that p53 activation is critical for the pathogenesis of HFpEF. We show that short telomere animals exhibit a basal level of p53 activation, mitochondria upregulate mtDNA encoded genes as a mean to compensate for blocked mitochondrial biogenesis, and loss of myocardial p53 prevents HFpEF upon HFD + L-NAME challenge. Overall design: Cardiomyocyte mRNA profiles of 16weeks old wild type (WT) and second generation TERC-/- (mTRG2) mice,which had fed 8 weeks L-NAME and high fat diet.