Study On The Role And Mechanism Of SIRT2 In Cerebral Ischemia-Reperfusion Injury

Acute ischemic stroke(AIS)has a high morbidity,disability and lethal rate,which seriously affects human health.At present,there are still great challenges in the treatment of AIS.Silent information regulator factor 2 related enzyme 2(SIRT2)has a very important role in a variety of neurological diseases,but its role in acute cerebral ischemia-reperfusion injury has not been determined.In order to clarify the effect of SIRT2 on ischemic brain injury and the underlying mechanism,this topic has been studied in clinical,animal and cellular aspects,with a view to providing new ideas for the treatment of AIS.Part 1: Clinical study on the expression of serum exosomal SIRT2 in acute ischemic stroke.Objective: To understand the relationship between SIRT2 level and the occurrence,severity and prognosis of AIS.Methods: ELISA was used to detect the SIRT2 level in serum exosomes of the AIS patient group(n = 120)and AIS high-risk control group(n = 60).The severity of AIS neurological deficit was assessed by the National Institutes of Health Stroke Scale(NIHSS).And modified Rankin score scale(m RS)was to evaluate the prognosis of AIS.Results: The serum exosomal SIRT2 level of AIS patients was significantly higher than that of AIS high-risk group(P <0.001).Multivariate analysis showed that SIRT2 level was positively correlated with the severity of neurological deficits(P <0.001)while the SIRT2 level was not independently related to the 90-day poor prognosis(P> 0.05)in AIS patients.Conclusion: Serum exosome SIRT2 level is positively correlated with the occurrence and severity of AIS.Part 2: The effect of inhibiting SIRT2 activity on brain injury of ischemiareperfusion animalsObjective: To explore the protective effect of inhibiting SIRT2 activity on cerebral ischemia-reperfusion injury.Methods: The middle cerebral artery occlusion(MCAO)model mice and SIRT2 activity inhibitor AK-7 were used in the research.The suspended tail test,corner test,wooden stick test,balance beam test,and Longa method neuroethology scores were used to assess the severity of neurological deficits in mice,and TTC staining was used to calculate the volume of cerebral infarction.Results: After inhibiting the activity of SIRT2,the neurological deficit of MCAO mice was significantly reduced(P <0.001),and the volume of cerebral infarction was significantly reduced(P <0.001).Conclusion: Inhibiting SIRT2 activity can significantly ameliorate cerebral ischemia-reperfusion injury.Part 3: The mechanism underlying protective effects of SIRT2 inhibition on cerebral ischemia-reperfusion injury.Objective: To explore the mechanism of inhibiting SIRT2 activity to improve cerebral ischemia-reperfusion injury.Methods:(1)The knockdown SIRT2 plasmid and the cell model of oxygen deprivation / reoxygenation(OGD / R)was constructed to analyze the levels of ?-tubulin and acetylated ?-tubulin,P38 and p P38,and SIRT2 by Western blot.Co IP was performed to determine the interaction between SIRT2 and P38.(2)Constructing MCAO model mice,the suspended tail test,corner test,wooden stick test,balance beam test,and Longa method neuroethology scores were performed to evaluate the severity of neurological deficits.Western blot analysis was used to determine the above proteins,and TTC staining was used to detect cerebral infarction volume.Results:(1)Both SIRT2 and P38 were activated in OGD / R cells,and P38 activity was further enhanced after inhibiting SIRT2 activity.Co-immunoprecipitation test revealed that P38 could bind to SIRT2.(2)P38 is activated in the brain of MCAO mice,and SIRT2 inhibition could not only further increase the activity of P38,but also reduce the neurological deficit and infarct volume caused by ischemia-reperfusion.Simultaneously inhibiting the activity of SIRT2 and P38,this protective effect was weakened obviously.Conclusion: The protective effect of SIRT2 activity inhibition in cerebral ischemia-reperfusion injury was achieved by activating P38.In summary,this study shows that the level of serum exosomal SIRT2 is positively correlated with the severity of neurological deficits in AIS patients.Inhibition of SIRT2 activity can significantly reduce the ischemia-reperfusion injury in MCAO mice.Cell experiments and animals studies have verified that inhibition of SIRT2 activity could improve cerebral ischemia-reperfusion injury by activating P38.The results of this study not only help to deeply understand the pathophysiological mechanism of cerebral ischemia-reperfusion injury,but also provide a valuable scientific basis for the clinical search for new AIS treatment strategies.