Silencing ATF4 inhibits JMJD3‐dependent JUNB/ETS1 axis and mitigates cerebral ischemic injury

Activating transcription factor 4 (ATF4) is known to play an important role in cerebral ischemia through apoptosis and neuron regulation. Histone demethylase JMJD3, specifically removing the methylation of H3K27me3, is highlighted to attenuate cerebral ischemic injury. However, few studies have explored the interaction between ATF4 and JMJD3 in this disease. Thus, we intended to explore the effect of ATF4 on cerebral ischemia. We first constructed a mouse model of middle cerebral artery occlusion (MCAO) and cultured PC12 cells. Specifically, the regulatory function of ATF4 and demethylase JMJD3 on the ischemic injury was explored via using ectopic expression and depletion by determination of modified neurologic severity score, blood-brain barrier, brain water content, apoptosis, infarct size, oxidative stress, and inflammation. Moreover, the interaction among ATF4, JUNB, JMJD3, and ETS1 was assessed by western blot analysis, immunofluorescence, immunoprecipitation, and dual-luciferase reporter gene assay. These data showed that ATF4 and JMJD3 were upregulated in the MCAO model and PC12 cells. In addition, ectopic expression of ATF4 aggravated the ischemic injury through demethylation of JMJD3. Meanwhile, JMJD3 upregulated JUNB expression by inhibiting H3K21me2/3 enrichment and promoted ETS1 expression as well. Altogether, ATF4 could exacerbate cerebral ischemic injury through JMJD3-dependent upregulation of JUNB/ETS1 expression, suggesting a potential theoretical basis of treatment for cerebral ischemic injury.