Silencing Of LncRNA XIST Impairs Angiogenesis And Exacerbates Cerebral Vascular Injury After Ischemic Stroke

Objective The aim of this study was to investigate the function and regulatory mechanism of long non-coding RNA(lncRNA)X-inactive-specific transcript(XIST)in cerebral ischemic stroke(CIS).Methods The changes of lncRNA XIST in serum of patients with acute ischemic stroke,ischemic brain tissue of mice and cerebrovascular endothelial cells after OGD/R were detected by q RT-PCR.Small hairpin RNA(sh RNA)-lncRNA XIST(si-XIST)was injected into the lateral ventricle to reduce the expression of lncRNA XIST in the brain of mice,and then MCAO(middle cerebral artery occlusion)was performed on one side to establish the model of ischemia reperfusion injury.Modified Neurological Severity Score(m NSS),infarct volume and TTC(triphenyl tetrazolium chloride)staining were used to evaluate brain injury.Immunofluorescence or dual immunofluorescence staining was used to evaluate the expression of relevant indicators in the ischemic hemisphere of sham mice(sham)or si-Ctl and si-XIST treated mice after 7 days of ischemia reperfusion.At the same time,Western blot was used to detect the expression of related indicators in the cerebrovascular endothelial cells(b End3)transfected with si-XIST after OGD(Oxygen–glucose deprivation and restoration)recovery for 24 h and in the si-Ctl treatment group.The effect of lncRNA XIST on the migration and tube formation of b End3 cells after OGD/R was detected by migration assay and tube formation assay.To study the effects of lncRNA XIST on brain endothelial cell migration,tube formation and the expression of related indicators after cerebral ischemia by overexpression of Itgα5 or KLF4.After the OGD of b End3 cells co-transfected with si-Ctl or si-XIST and/or mir-92a-I was recovered for 24 h,the role of mi R-92 a in cerebrovascular injury after lncRNA XIST regulation of CIS was analyzed by Western blot,migration assay and tube formation assay.Results Our results demonstrated that the expression of lncRNA XIST decreased during the early stages of CIS but then increased in the later stages in CIS patients and ischemic models in vivo and in vitro.In addition,the serum levels of lncRNA XIST negatively correlated with severity of neurological impairment of CIS patients.Further studies exhibited that lncRNA XIST regulated the expression of proangiogenic factor-integrin α5(Itgα5)and anti-inflammation factor-Kruppel-like transcription factor 4(KLF4)by targeting micro RNA-92a(mi R-92a).Silencing of lncRNA XIST impaired angiogenesis and exacerbated cerebral vascular injury following CIS,leading to larger infarcts and worse neurological deficits in transient MCAO mice.Mechanistic analysis revealed that lncRNA XIST modulated angiogenesis and alleviated cerebral vascular injury following CIS through mediating the mi R-92a/Itgα5 or KLF4 axis,respectively.Conclusion These data indicate that lncRNA XIST can induce angiogenesis and reduce cerebrovascular injury after CIS by mediating mi R-92a/Itgα5 or KLF4 axis,providing a new approach for the treatment of CIS.