Synaptotagmin-3 Interaction With AMPA Receptor GluA2 Subunit In Cerebral Ischemia/Reperfusion Injury

Background:Synaptotagmin Ⅲ(Syt3)is a Ca2+-dependent membrane-traffic protein that is highly concentrated in synaptic plasma membranes.AMPA receptors(AMAPRs)are tetramers composed of GluA1-GluA4 subunits.GluA2-lacking AMPARs are also known as Ca2+permeable AMPARs(CP-AMPRs).Abnormal Ca2+influx into CP-AMAPRs is believed to be the cause of neuronal death associated with many brain diseases.Existing research shows that Syt3 can bind to and internalize GluA2.Purpose:This study aims to investigate the role and mechanism of the Syt3-GluA2 interaction in cerebral ischemia/reperfusion(I/R)injury.Methods:A middle cerebral artery occlusion/reperfusion(MCAO/R)model in adult male Sprague Dawley(SD)rats(250-300g)was established to imitate cerebral I/R injury.The overexpression and knockdown lentivirus were administered to rats by intra-penumbra injection,and the TAT-GluA2-3Y peptide was delievered to rats by intraperitoneal injection.Results:First,I/R injury enhanced the Syt3-GluA2 interactions.Secondly,knockdown of Syt3 protected against cerebral I/R injury,promoted recovery of motor function,inhibited cognitive decline,reduced Syt3-GluA2 interactions,and increased surface expression of GluA2.Third,overexpression of Syt3 further increases the Syt3-GluA2 interactions,reduced GluA2 surface expression,and aggravated I/R insults.Finally,the dissociating the Syt3GluA2 interactions using TAT-GluA2-3Y peptide resulted in improved recovery from neurological impairments,improved cognitive function,and increased the surface expression of GluA2,suggesting that neuroprotection may involve decreasing the expression of CP-AMPARs induced by Syt3-GluA2 interactions.Conclusion:Restriction of Syt3-GluA2 interactions may alleviate cerebral I/R injury by inhibiting the surface expression of CP-AMPARs;thus,regulation of Syt3-GluA2 interaction and CP-AMPARs formation may be a novel target for the treatment of I/R injury.