瘦素抑制冈田酸诱导的SH-SY5Y细胞Cdk5的表达

Leptin inhibits okadaic acid- induced Cdk5 expression in SH-SY5Y cells

目的探讨瘦素(leptin)与阿尔茨海默病的联系。方法将人神经纤维母细胞瘤细胞系(SH-SY5Y)分为3组:对照组、冈田酸(okadaic acid,OA)损伤模型组(40 nmol/L OA诱导12 h)和Leptin处理组。用OA诱导SH-SY5Y,建立阿尔茨海默病细胞模型。Leptin处理组是在模型组基础上,给予外源性leptin(0.4μg/ml)处理6 h,用Western Blot检测细胞周期依赖性蛋白激酶5(Cdk5)和β-actin蛋白表达水平。瘦素受体(ObR)和Cdk5的共定位情况用双重免疫荧光染色检测。结果模型诱导成功后,Western Blot显示Cdk5表达明显升高(P<0.01);给予leptin后,Cdk5蛋白表达显著降低(P<0.01)。双染法免疫荧光实验表明,SH-SY5Y细胞中ObR和Cdk5蛋白均主要在细胞质中表达,并且红色和绿色标记重叠为橙色荧光,可认为两种蛋白共定位,提示ObR和Cdk5之间可能存在相互作用。结论 Leptin能够在体外降低阿尔茨海默病相关的Cdk5表达,为其治疗提供了新靶点。

Abstract： Objective To study the association between leptin and Alzheimer＇s disease （AD）. Methods SH-SY5Y cells were randomly divided into control group, Okadaic acid （OA） injury model group, and leptin treatment group. An AD model was established by inducing SH-SY5Y with 40nmol/L OA. Leptin treatment group was treated with 0.4μg/ml exogenous leptin for 6 h. Expression levels of cell cycle-dependent Cdk5 and β -actin proteins were measured by Western blot. ObR and Cdk5 co- localization was detected by dual immunofluorescent staining assay. Results Western blot showed that the Cdk5 expression level was significantly higher after the model was established （P 〈 0.01） and significantly lower after leptin was given （P 〈 0.01）. Double immunofluorescence staining assay showed that the ObR and Cdk5 proteins were expressed mainly in cytoplasm of SH-SY5Y ceils. The red and green markers were overlapped into orange fluorescence, which could be considered as the co-localization of the two proteins, suggesting that ObR interacts with Cdk5. Conclusion Leptin can down-regulate Alzheimer＇s disease-related Cdk5 exoression in vitro, thus providing a new target for the treatment of Alzheimer＇s disease.