Abstract
Diabetic cardiomyopathy (DCM) is one of the complications triggered by type II diabetes (T2D) (1). When free fatty acids (FFA) are abundant in insulin resistant pre-diabetic patients because of adipose lipolysis, FFA tends to move toward heart (2). Lipid accumulation can cause cardiac lipotoxicity and exacerbate DCM (3). In previous study, Pgrmc1 has been identified to associate with fatty acid synthesis (4). Therefore, we assumed that Pgrmc1 will associate with DCM. By feeding high-fat diet for 8 weeks and injecting streptozotocin (30mg/kg), T2D and DCM were induced. The lipid accumulation was exacerbated in T2D-induced Pgrmc1 KO heart, and FFA level was also high. Levels of lipid metabolic genes showed the tendency for lipid accumulation and lipotoxicity, and glycolysis was induced in T2D-induced Pgrmc1 KO heart. Though glycolysis presents higher efficiency for energy production in cardiomyopathy (5), it did not compensate the impairment of mitochondrial respiration in Pgrmc1 KO heart. High-fat diet and streptozotocin could not be the interfering factors, because suppression of fatty acid oxidation, induction of glycolysis, and impairment of mitochondrial respiration were observed similarly in post-prandial mice which were fed with normal chow. Insulin was excluded for interfering factor as cell line with serum starvation showed mitochondrial suppression and glycolytic induction in flux analyzer analysis in Pgrmc1 knockdown. Conversely, induction of fatty acid oxidation and suppression of glycolysis were observed in 72 h fasting of Pgrmc1 KO heart, suggesting the nutrition is closely associated with the metabolic modulation of Pgrmc1 on heart. This metabolic phenotype of Pgrmc1 KO heart consequently exacerbated DCM by showing high levels of fibrosis, inflammation, endoplasmic reticulum stress, and oxidative stress. References: (1) Jia G, Hill MA, Sowers JR. Diabetic Cardiomyopathy: An Update of Mechanisms Contributing to This Clinical Entity. Circulation research. 2018;122:624-38. (2) Noll C, Carpentier AC. Dietary fatty acid metabolism in prediabetes. Current opinion in lipidology. 2017;28:1-10. (3) Goldberg IJ, Trent CM, Schulze PC. Lipid metabolism and toxicity in the heart. Cell metabolism. 2012;15:805-12. (4) Lee SR, Kwon SW, Kaya P, Lee YH, Lee JG, Kim G, et al. Loss of progesterone receptor membrane component 1 promotes hepatic steatosis via the induced de novo lipogenesis. Scientific reports. 2018;8:15711. (5) Nagoshi T, Yoshimura M, Rosano GM, Lopaschuk GD, Mochizuki S. Optimization of cardiac metabolism in heart failure. Current pharmaceutical design. 2011;17:3846-53.