叶黄素抑制叔丁基过氧化氢诱导的视网膜神经节细胞凋亡

目的:观察叶黄素(lutein)对叔丁基过氧化氢(t-BHP)处理的视网膜神经节细胞(RGC-5细胞系)的保护效应并探讨其作用机制。方法:用免疫荧光染色检测视网膜神经节特异性蛋白Brn-3和神经微管结合蛋白MAP-2的表达来鉴定RGC-5细胞;将RGC-5细胞随机分为对照组、t-BHP处理组、t-BHP和lutein共同处理组、lutein处理组,培养24 h,MTT实验检测细胞活力;Annexin V-FITC/PI双染流式细胞术检测细胞凋亡;免疫细胞化学技术检测caspase-3蛋白的活化情况;Western blot检测Bcl-2/Bax、cleaved caspase-3、JNK和c-Jun蛋白的变化。结果:MTT实验和流式细胞检测结果显示,lutein能提高t-BHP处理的RGC-5细胞的活力,并降低t-BHP诱导的RGC-5细胞凋亡;免疫荧光结果显示lutein能抑制t-BHP诱导的caspase-3的活化;与对照组比较,t-BHP处理后RGC-5细胞抗凋亡蛋白Bcl-2表达下调(P0.05),Bax/Bcl-2比率升高,cleaved caspase-3表达上调(P0.05),JNK和c-Jun蛋白的磷酸化水平增加(P0.05),t-BHP的上述作用可被lutein部分逆转。结论:Lutein能够降低t-BHP诱导的RGC-5细胞凋亡,其机制与其上调Bcl-2的表达、抑制caspase-3的活化并降低JNK和c-Jun蛋白的磷酸化有关。

Lutein suppresses t-BHP-induced apoptosis in retinal ganglion cells

AIM: To investigate the protective effects of lutein on retinal ganglion cells in vitro. METHODS: The effect of lutein on tert-butyl hydroperoxide (t-BHP)-treated retinal ganglion cells (RGC-5 cell line) was determined. The protein expression of Brn-3 and MAP-2 was examined by the method of immunocytochemistry to identify the RGC-5 cells. The RGC-5 cells were induced by a 24 h exposure of t-BHP, and the cell viability was examined by MTT assay. The apoptotic ratio of the RGC-5 cells after exposed to t-BHP or/ and lutein treatment was analyzed by flow cytometry assay with Annexin V-FITC /PI staining. The activation of caspase-3 was detected by immunocytochemistry and the protein levels of Bcl-2, Bax, cleaved caspase-3, JNK and c-Jun were determined by Western blot. RESULTS: The RGC-5 cells expressed Brn-3 and MAP-2 proteins. Lutein treatment prevented t-BHP-induced RGC-5 cell apoptosis and increased the cell activity. Compared with control group, exposure of the RGC-5 cells to t-BHP decreased the expression of anti-apoptotic protein Bcl-2, increased the Bax/Bcl-2 ratio, up-regulated the level of cleaved caspase-3, also promoted the phosphorylation of JNK and c-Jun. Lutein partly reversed the effects of t-BHP on the RGC-5 cells mentioned above. CONCLUSION: Lutein protects RGC-5 cells against t-BHP-induced apoptosis by up-regulating Bcl-2 expression and inhibiting caspase-3 activation through modulating the JNK signaling pathway.