Abstract P312: The Essential Role Of Prak In Preserving Cardiac Function And Insulin Resistance In High Fat Diet-induced Diabetes

Background: p38 regulated/activated protein kinase (PRAK) plays a crucial role in modulating cell death and survival. However, the role of PRAK in mediating cardiac dysfunction and metabolic disorders remains unclear. We examined the effects of deletion of PRAK on modulating cardiac function and insulin resistance in mice exposed to a high fat diet (HFD). Methods: Wild type and PRAK -/- mice at 8 weeks old were exposed to either chow food or HFD for a consecutive 16 weeks. Glucose tolerance test and insulin tolerance test were employed to assess insulin resistance. Echocardiography was employed to assess myocardial function. Western blot was used to determine the molecular signaling involved in phosphorylation of IRS-1, AMPKα, ERK-44/42, and irisin. Real time-PCR was used to assess the hypertrophic genes of the myocardium. Histological analysis was employed to assess the hypertrophic response, interstitial myocardial fibrosis, and apoptosis in the heart. Results: HFD induced metabolic stress is indicated by glucose intolerance and insulin intolerance. PRAK knockout aggravated insulin resistance, as indicated by glucose intolerance and insulin intolerance testing as compared to wild type littermates. As compared to wild type, hyperglycemia and hypercholesterolemia were manifested in PRAK-knockout mice following high fat diet intervention. High fat diet intervention displayed a decline in fractional shortening (FS) and ejection fraction (EF). However, deletion of PRAK exacerbated the decline in EF and FS as compared to wild type mice following HFD treatment. In addition, PRAK knockout mice enhanced the expression of myocardial hypertrophic genes including ANP, BNP, and βMHC in HFD treatment, which was also associated with an increase in cardiomyocyte size and interstitial fibrosis. Western blot indicated that deletion of PRAK induces decreases in phosphorylation of IRS-1, AMPKα, and ERK44/42 as compared to wild type controls. Conclusion: Our finding indicates that deletion of PRAK promoted myocardial dysfunction, cardiac remodeling, and metabolic disorders in response to HFD.