BMAL1 involved in autophagy and injury of thoracic aortic endothelial cells of rats induced by intermittent heat stress through AMPK/mTOR/ULK1 pathway

Background The physiological activities of the body have obvious biological rhythm. As the core of circadian rhythm, BMAL1 is the only clock gene whose deletion can lead to abnormal physiological function. However, it has not been reported whether heat exposure at different time can affect cardiovascular function changes by changing the circadian rhythm of clock genes. This study aimed to investigate whether autophagy is mediated by AMPK/mTOR/ULK1 pathway under intermittent heat exposure, and the effect of BMAL1 expression on thoracic aortic autophagy and apoptosis. Methods Intermittent heat stress model was established in vitro and vivo, western blot and immunofluorescence were used to detect the expressions of autophagy, apoptosis, AMPK/mTOR/ULK1 pathway and BMAL1. And then Autophagy was inhibited and activated, western blot and immunofluorescence detected the changes of autophagy and apoptosis. Finally, BMAL1 was silenced, RT-qPCR detected the expression of autophagy and apoptosis. Results Our study suggested heat stress induced autophagy and apoptosis were in RTAECs. In addition, intermittent heat stress raised AMPK and ULK1 but reduced the phosphorylation of mTOR in RTAECs, and autophagy inhibition by compound C reversed the expression of phosphorylation AMPK, mTOR and ULK1, the expression of Beclin1 and LC3-II/LC3-I decreased compared to the group of intermittent heat stress in vitro. Furthermore, Rapamycin mediated autophagy promoted apoptotic effects, and autophagy inhibitor 3-Methyladenine (3-MA) depressed the expression of apoptosis in vitro. After administration of Rapamycin, LC3-II/LC3-I, Beclin1 and Bax were further upregulated, whereas 3-MA alleviated the cells death. Finally, BMAL1 was elevated in vitro and vivo, and shBMAL1 reduced the expression of autophagy and apoptosis. Conclusion We revealed that intermittent heat stress induced apoptosis and autophagy. BMAL1 may involve in the occurrence of autophagy and apoptosis by AMPK/mTOR/ULK1 pathway.