Drp1 knockdown aggravates obesity-induced cardiac dysfunction and remodeling.

Obesity is an independent risk factor for heart failure with preserved ejection fraction (HFpEF). Dynamin related protein 1 (Drp1) is a key regulator of mitochondrial morphology, bioenergetics and quality control. The role of endogenous Drp1 in obesity induced HFpEF remains largely unknown. Here, adult heterozygous Drp1 floxed (Drp1(fl/+)) mice were bred with αMHC-MerCreMer mice and injected with tamoxifen to induce heterogenous Drp1 knockout (hetCKO) in the heart. Control and hetCKO mice exhibited similar increases in body weight and blood glucose and developed insulin resistance after 18-week high-fat diet (HFD)-fed. HFD had no effect on cardiac contractility but induced diastolic dysfunction, fibrosis, cell death and inflammation in Control and hetCKO mice hearts. Importantly, all these adverse effects were exacerbated in the hearts of hetCKO mice, suggesting aggravated cardiac remodeling and diastolic dysfunction. HFD induced mitochondrial fission was blocked, whereas energy deficiency was exaggerated in hetCKO hearts. These effects were associated with suppressed mitochondrial quality control via mitophagy, and increased apoptosis and oxidative stress. These findings suggest that endogenous Drp1 may play an important role in limiting metabolic stress induced heart dysfunction through regulating mitophagy, oxidative stress, mitochondrial function, apoptosis, and inflammation. Our study provides critical insights into how endogenous Drp1 plays a beneficial role in metabolic stress-induced HFpEF.