The Protective Effect Of WDR26, An Ischemic Preconditioning-Related Gene, Against The Cerebral Ischemia-Reperfusion Injury

Cerebral ischemia-reperfusion injury is a common phenomenon which leads to neuronal death.Cerebral ischemic preconditioning is a powerful protective mechanism.It can prevent neural cells and astrocytes from apoptosis and necrosis induced by cerebral ischemia/reperfusion injury.Therefore,it is important to illustrate the mechanisms of cerebral ischemic preconditioning.WDR26 is identified as a novel gene which is up-regulated during myocardial ischemia/reperfusion.The completed cDNA of WDR26 is 3,729 bp,composed of an ORF of 1,545 bp.The WDR26 protein is 514 amino acids and the relative molecular mass is 58,603 Da(～59 kDa). Structural analysis reveals that the protein contains a conserved WD-40 region consisting six WD-40 repeats.WDR26 is expressed abundantly in most of tissues,including at a high level in brain.WD-40 repeat proteins play important roles in a variety of cellular functions,including cell growth,proliferation,apoptosis,and intracellular signal transduction. However,little is known about the role(s) of WDR26.In the present study,we firstly used meliorated four-vessel occlusion to copy global cerebral ischemic preconditioning and ischemia-reperfusion model of rat and to observe the protective effects of cerebral ischemic preconditioning on the following cerebral ischemia/reperfusion injury.Compared with the sham control group,the brain water content of experimental group which was treated 24 hours after operation with 30 minutes cerebral ischemia followed by 24 hours reperfusion was reduced.The results indicated the global cerebral ischemic preconditioning and ischemia-reperfusion model of rat was copied successfully.And the expression of WDR26 was significantly up-regualted following 3 minutes cerebral ischemic preconditioning.Secondly,hWDR26 plasmids and asODNs against WDR26 were used to reveal the role of WDR26 in response to oxidative stress in human SH-SY5Y neuroblastoma cells.The results showed that H₂O₂ at 0.5mM induced a marked increase of cell death and significant up-regulation of WDR26 expression.In addition,over-expression of WDR26 significantly supressed H₂O₂-induced SH-SY5Y cell death. asODNs markedly inhibited the de novo biosynthesis of WDR26,which contributed to enhanced cell death induced by H₂O₂.Moreover, over-expression of WDR26 down-regulated the transcriptional activity of AP-1 during H₂O₂-induced SH-SY5Y cell death.These data demonstrated that WDR26 was up-regulated by oxidative stress and played important roles in H₂O₂-induced SH-SY5Y cell death,which might be mediated by down-regulation of AP-1 transcriptional activity.Thirdly,the role of WDR26 in response to oxidative stress in human U251-MG glioma cells was detected.The results showed that H₂O₂ at 0.5mM induced a significant increase of cell death and up-regulation of WDR26 expression.In addition,over-expression of WDR26 significantly supressed H₂O₂-induced cell injury,asODNs against WDR26 enhanced cell death induced by H₂O₂.These data demonstrated that WDR26 was up-regulated by oxidative stress and played important roles in H₂O₂-induced U251-MG cell death.In together,for the first time we determined that WDR26 was a cerebral ischemic preconditioning related gene and it played important roles in protection from the cell death induced by oxidative stress in neuronal cells and astrocytes.The exact mechanisms are still under active investigation.