Beclin-1 exerts protective effects against cerebral ischemia-reperfusion injury by promoting DNA damage repair through a non-autophagy-dependent regulatory mechanism

Cerebral ischemia-reperfusion (I/R) can result in severe brain injury, for which there are no optimal treatment options. I/R is often accompanied by increased autophagy. Beclin-1, a central player in autophagy, has been extensively studied in I/R; however, to date, at least to the best of our knowledge, there are no definitive descriptions of its specific role. Thus, the aim of the present study was to explore the regulatory role played by Beclin-1 in I/R. In vivo experiments were performed using an animal model of brain I/R with male Sprague-Dawley rats. Brain tissue damage was observed using 2,3,5-triphenyltetrazolium chloride, and hematoxylin and eosin staining. Tissue apoptosis levels were evaluated using a TUNEL assay, as well as western blot analysis. Immunofluorescence together with western blot analysis was used to detect autophagy in the tissues. Immunohistochemistry and western blot analysis were used to analyze DNA double-stranded breaks (DSBs). Moreover, HT22 cells overexpressing Beclin-1 were subjected to oxygen glucose deprivation/reoxygenation injury to simulate I/R pathological damage in vitro. Apoptosis was assessed using TUNEL and flow cytometric assays in this in vitro model, and autophagy was assessed using immunofluorescence and western blot analysis. The DSBs of the cells were analyzed using western blot analysis. I/R activated autophagy and induced DSBs. Autophagy inhibitors decreased brain tissue damage and reduced cell apoptosis; however, the degree of decrease in damage and apoptosis was not highly associated with the change in autophagy, and the frequency of DSBs slightly increased. The overexpression of Beclin-1 in neurons significantly attenuated I/R-induced damage and promoted DSB repair. On the whole, the present study demonstrates that Beclin-1 protects neurons from ischemic damage through the non-autophagy-dependent regulation of DNA repair processes.