Abstract

BACKGROUND Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) regulates the expression of clock gene nuclear receptor subfamily 1 group D member 1 (NR1D1) and is closely related to diabetes mellitus and ischemic heart disease. However, the mechanism by which PGC-1α/NR1D1 increases the vulnerability of diabetic myocardium to ischemia/reperfusion (I/R) injury has yet to be elucidated. This study aimed to explore the roles of PGC-1α/NR1D1-mediated regulation of mitochondrial biogenesis in myocardial I/R injury of type 2 diabetic mice. METHODS Type 2 diabetes was induced in C57BL/6 mice by a high-fat diet and streptozotocin. Diabetic and nondiabetic mice underwent I/R injury, with subsets receiving the NR1D1 agonist SR9009 or cardiac-specific Nr1d1 knockout. In parallel, rat cardiomyocyte-derived cell line H9c2 cardiomyocytes were exposed to high glucose and high fat and hypoxia/reoxygenation insult, with or without Pgc-1α overexpression by Pgc-1α lentivirus. Cardiac function in mice was assessed using an animal ultrasound system. Myocardial infarction size was determined by 2% 2,3,5-triphenyltetrazolium chloride (TTC) staining. Serum levels of troponin I (cTn-I) and lactate dehydrogenase (LDH) were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of NR1D1, PGC-1α, nuclear respiratory factor 1 (NRF1), transcription factor A (TFAM), ‌autophagy-related protein 4 homolog B (ATG4B), and microtubule-associated protein 1 light chain 3 (LC3) in mouse myocardial tissue were detected by real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and immunofluorescence. Meanwhile, the cell viability, apoptosis rate, mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and mitochondrial morphology of H9c2 cardiomyocyte were evaluated using assay kits. RESULTS