Hypoxia-inducible factor-2alpha in focal cerebral ischemia

Stroke is one of the major reasons for death and disability. Insufficient blood flow in stroke interferes the brain from proper oxygenation, leading to the stabilization of hypoxia-inducible factors (HIFs). To determine the role of HIFs in stroke, particularly HIF-2α, an in vivo model called tMCAO (transient middle cerebral artery occlusion) and an in vitromodel with human SH-SY5Y cells was used. On both, Hif-2α deficient and wild type mice, tMCAO was conducted for two hours. In addition to RNA and protein samples, tissue for immunofluorescence microscopy was collected of ischemic and control brains. To simulate stroke in SY5Y cell culture, oxygen-glucose-deprivation (OGD) experiments were performed under 0.2% oxygen and without glucose. RNA and Protein samples were taken hourly for up to 4 hours, following 1 or 24 hours of reperfusion. Prior to reperfusion, either Roxadustat or a selective HIF-2α inhibitor (PT-2358) were administered. First results show a significant increased expression of HIF-2α regulated neurotrophic factors, already after one hour of OGD, while the inhibition of HIF-2α during reperfusion leads to significantly less cell death.Preliminary results lead to the conclusion that HIF-2α might influence the outcome after ischemia and reperfusion in a time-dependent manner. Future experiments should elucidate the effects of HIF-2α during stroke and after reperfusion by analyzing more HIF-2α target genes via qPCR, getting more insights of the HIF-2α regulation by Western Blot analysis and immunofluorescence microscopy, to better understand the cellular response to ischemia and reperfusion, which may pave the way for new therapeutically approaches.