Mammalian Diaphanous-related formin 1 (mDia1) inducing diabetic cardiomyopathy by regulating metabolic reprogramming

Abstract Background Mammalian Diaphanous-related formin 1 (mDia1) is one of the formin family proteins and acts as a rho-effector molecule which is involved in actin organization. Previous studies showed that mDia1 aggravated compensatory cardiac hypertrophy in response to pressure overload. However, the role of mDia1 in diabetic cardiomyopathy and its mechanisms remain elusive. Objective To clarify the mechanisms of mDia1 in DCM through mediating metabolic reprogramming. Methods 5-week-old of mDia1 ko mice were used to induce DCM by feeding high-fat diet (HFD) for 16 weeks. The blood glucose and body weight of the mice were measured regularly. Echocardiography was used to evaluate cardiac function. HE and WGA staining were used to evaluate hypertrophy of cardiomyocytes. Transmission electron microscopy and mitotracker staining were used to observe the morphology of mitochondrial in heart. Proteomics and metabolomics were used to explore the metabolites in hearts of mice. Primary neonatal cardiomyocytes were isolated and stimulated with 35 mM glucose and 250 μM palmitate in vitro. Adenovirus expressing shRNA of mDia1 was used to knockdown mDia1 in cardiomyocytes. Mitochondria were isolated from primary cardiomyocytes to verify the translocation of mDia1. Co-Immunoprecipitation was used to confirm the interaction between mDia1 with succinate dehydrogenase subunits A (SDHA). Results mDia1 had no effects to blood glucose and body weight after 16-week HFD feeding. Loss of mDia1 ameliorated diastolic dysfunction in DCM mice with shorter isovolumic relaxation time (IVRT) and increased E/A ratio in left ventricular. In addition, cardiac hypertrophy was significantly improved in mDia1 ko mice. mDia1 deficiency tended to maintain the normal mitochondrial structure. Results of proteomics showed that mDia1 was involved in mitochondrial function, ATP synthesis and metabolic pathways. Metabolomics showed that HFD induced accumulation of α-ketoglutaric acid in wild type mice compared with mDia1 ko mice. However, mDia1 ko significantly increased fumaric acid but did not affect succinyl-CoA and succinic acid compared with wild type mice. Furthermore，we found that mDia1 translocated into mitochondrial with high glucose and palmitate stimuli. Results of CoIP showed mDia1 interacted with SDHA both in cardiomyocytes and HEK293 cells. Conclusions mDia1 deteriorated DCM through translocating into mitochondrial and interacting with SDHA, a process dependent on metabolic pathways.Figure of Mechanism