Silencing of peroxisome proliferator‐activated receptor‐alpha alleviates myocardial injury in diabetic cardiomyopathy by downregulating 3‐hydroxy‐3‐methylglutaryl‐coenzyme A synthase 2 expression

Diabetic cardiomyopathy (DCM) is a cardiac disorder, which affects around 12% diabetic patients, resulting in overt heart death. Our initial bioinformatic analysis identified the differentially expressed gene 3-hydroxy-3-methylglutaryl-coenzyme A synthase 2 (HMGCS2) in DCM, which may be activated by peroxisome proliferator-activated receptor-alpha (PPARα) based on previous evidence. Therefore, the present study aims to explore the effect of PPARα on the development of DCM through regulating HMGCS2. The expression of PPARα and HMGCS2 was detected by reverse transcription quantitative polymerase chain reaction in cardiomyocytes and high-glucose-cultured cardiomyocytes. The proliferation and apoptosis of cardiomyocytes were examined by 5-ethynyl-2'-deoxyuridine assay and flow cytometry, separately. Mitoehondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) levels were determined. Then, the protein levels of B-cell lymphoma 2, Bcl-2-associated X protein, and cleaved Caspase-3 were detected by Western blot analysis. The myocardial apoptosis index, heart weight, and serum lipids of rats were examined. At last, the expressions of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), transforming growth factor β1 (TGFβ1), peroxisome proliferator activator receptor gamma coactivator-1 alpha (PGC1α), nuclear respiratory factor (NRF)-1, NRF-2, NAD(P)H oxidase 1, and superoxide dismutase-1 were examined. HMGCS2 was the most differentially expressed gene in DCM. The levels of HMGCS2 and PPARα were upregulated in patients with DCM. HMGCS2 silencing was shown to inhibit HMGCS2 expression to suppress the apoptosis of high-glucose-induced cardiomyocytes and the loss of MMP, reduce the accumulation of ROS, and promote cardiomyocyte proliferation. Silencing of HMGCS2 and PPARα alleviated myocardial injury, decreased blood glucose, and lipid in DCM rats, downregulated the expression of ANP, BNP, and TGFβ1 to reduce myocardial injury, and elevated PGC1α, NRF-1, and NRF-2 levels to enhance oxidative stress levels. Our results demonstrated that silencing of PPARα could alleviate cardiomyocyte injury and oxidative stress via a mechanism related to the downregulation of HMGCS2, which could provide a novel target for DCM treatment.