H3K27ac-Activated lncRNA-DAPK1-IT1 Aggravated Oxidative Stress Damage Induced by Focal Cerebral Ischemia/Reperfusion via the miR-25-3p/HMGB1 Molecular Axis

Ischemic stroke is a prevalent neurological disorder, characterized by elevated mortality and significant long-term disability. Oxidative stress damage is an important pathological process that occurs after brain ischemia/reperfusion (I/R), in which the long non-coding RNA death-associated protein kinase 1 intronic transcript 1 (DAPK1-IT1) is aberrantly expressed and participates in oxidative stress damage; however, its specific mechanisms of action remain unclear. DAPK1-IT1 and miR-25-3p expression was detected using qRT-PCR in the mouse neuroblastoma N2a cells that received middle cerebral artery occlusion/reperfusion and oxygen-glucose deprivation/reperfusion. Functional gain and loss experiments were performed to manipulate DAPK1-IT1, miR-25-3p, and HMGB1 expression. The role of DAPK1-IT1 was assessed both in vivo and in vitro using CCK-8, flow cytometry, and western blotting. The results showed that the levels of DAPK1-IT1, HMGB1, and oxidative stress damage markers were significantly increased, whereas miR-25-3p expression was significantly downregulated. The expression levels of DAPK1-IT1 were positively correlated with ROS production. DAPK1-IT1 and HMGB1 were identified as potential targets of miR-25-3p. Knockdown of DAPK1-IT1 and HMGB1, as well as overexpression of miR-25-3p, is indeed protective and contribute to reducing oxidative stress damage by activating the Nrf2/HO-1 signaling pathway. DAPK1-IT1 overexpression caused oxidative stress damage in N2a cells by downregulating miR-25-3p expression and upregulating HMGB1 expression. Mechanistically, DAPK1-IT1 upregulated HMGB1 expression by sponging miR-25-3p and mediating histone H3 lysine 27 acetylation in the promoter region through the cAMP response element-binding protein-binding protein (CBP). In summary, we found that H3K27 acetylation-induced lncRNA-DAPK1-IT1 promotes oxidative stress damage caused by I/R through the miR-25-3p/HMGB1 axis. These findings help to improve our understanding of ischemic stroke and provide new therapeutic avenues.