CaMKⅡγ和CaMKⅡδ通过PI3K/Akt/Erk信号通路减轻小鼠神经元缺血再灌注损伤

PI3K/Akt/Erk signaling pathway mediates neuroprotection of CaMKⅡγ and CaMKⅡδ against ischemic reperfusion injury in mice

目的观察钙/钙调蛋白依赖性激酶Ⅱ(CaMKⅡ)的同工型CaMKⅡγ和CaMKⅡδ对鼠神经元细胞缺血缺氧再灌注损伤的影响,并探究其作用机制。方法分离胚胎期第18天胎鼠大脑用于提取原代神经元,在5%CO_(2)、37℃条件下培养,分为常规培养的对照组、空白对照组(si-NT)、CaMKⅡγ敲除组(si-CAMK2G)和CaMKⅡδ敲除组(si-CAMK2D)。研究组神经元转染处理后,更换为无糖培养基,并将其置于缺氧环境中模拟氧糖剥夺(OGD/R)条件,持续1 h,随后复原标准培养环境。通过对神经元裂解物行免疫蛋白印迹检测磷脂酰肌醇-3-激酶/细胞外信号调节激酶(PI3K/Akt/Erk)信号通路构件的表达量,并建立小鼠大脑中动脉闭塞(MCAO)模型,通过对比假手术组(Sham)(n=25)和MCAO组(n=25)PI3K/Akt/Erk信号通路表达来进行验证。结果si-CAMK2G组的胎鼠神经元细胞在OGD/R 12、24、48、72 h的生存率明显低于si-NT组(P<0.01或0.001),并可逆转OGD/R介导的胎鼠神经元细胞CaMKⅡγ表达上调。si-CAMK2G组和si-CAMK2D组与si-NT组相比,PI3K/Akt/Erk信号通路表达受到明显抑制(P<0.01)。在MCAO模型中,MCAO组小鼠脑CaMKⅡδ和CaMKⅡγ的表达显著增加并激活了PI3K/Akt/Erk信号通路,CaMKⅡδ和CaMKⅡγ,Erk、磷酸化Erk、Akt和磷酸化Akt在MCAO造模成功再灌注后24、48、72和96 h的表达显著高于Sham组再灌注24 h(P<0.05,0.01或0.0001)。结论CaMKⅡγ和CaMKⅡδ在神经元细胞发生缺血缺氧损伤时的神经保护作用可能是通过PI3K/Akt/Erk信号通路介导的。

Objective To observe neuroprotective effects of Ca2+/calmodulin-dependent kinaseⅡ(CaMKⅡ)γand CaMkIIδagainst acute neuronal ischemic reperfusion injury in mice and explore the underlying mechanism.Methods Primary cultures of brain neurons isolated from fetal mice(gestational age of 18 days)were transfected with two specific siRNAs(si-CAMK2G and si-CAMK2D)or a control sequence(si-NT).After the transfection,the cells were exposed to oxygen-glucose deprivation/reperfusion(OGD/R)conditions for 1 h followed by routine culture.The expressions of phosphatidylinositol-3-kinase/extracellular signal-regulated kinase(PI3K/Akt/Erk)signaling pathway components in the neurons were detected using immunoblotting.The expressions of the PI3K/Akt/Erk signaling pathway proteins were also detected in the brain tissues of mice receiving middle cerebral artery occlusion(MCAO)or sham operation.Results The neuronal cells transfected with siCAMK2G showed significantly lower survival rates than those with si-NT transfection at 12,24,48,and 72 h after OGD/R(P<0.01),and si-CAMK2G transfection inhibited OGD/R-induced upregulation of CaMKIIγexpression.Compared to si-NT,transfection with si-CAMK2G and si-CAMK2D both significantly inhibited the expressions of PI3K/Akt/Erk signaling pathway components(P<0.01).In the mouse models of MCAO,the expressions of CaMKIIδand CaMKIIγwere significantly increased in the brain,where activation of the PI3K/Akt/Erk signaling pathway was detected.The expression levels of CaMKIIδ,CaMKIIγ,Erk,phosphorylated Erk,Akt,and phosphorylated Akt were all significantly higher in MCAO mice than in the sham-operated mice at 24,48,72,and 96 h after reperfusion(P<0.05).Conclusion The neuroprotective effects of CaMKIIδand CaMKIIγagainst acute neuronal ischemic reperfusion injury are mediated probably by the PI3K/Akt/Erk pathway.