中文摘要：

目的：探讨Aβ25-35介导SH-SY5Y细胞Bcl-2、Bax基因表达改变是否通过基因启动子区甲基化的机制。方法不同浓度Aβ25-35（0、25、50μmol？ L-1）分别作用于体外培养的SH-SY5Y细胞48、72 h，MTT法确定Aβ25-35诱导SH-SY5Y细胞凋亡的最佳浓度和时间。 Western blot 检测不同药物处理组细胞凋亡相关蛋白Bcl-2、Bax表达变化，Real time PCR检测DNA甲基化酶DNMT1、DNMT3a、DNMT3b、MeCP2的mR-NA水平。 Methylation specific PCR （ MSP）法分析Aβ25-35介导的Bcl-2、Bax基因启动子区甲基化水平的变化。结果25μmol·L^-1 Aβ25-35暴露SH-SY5Y细胞72 h后，MTT检测细胞存活率达（68．49±9．83）％，与对照组比较明显降低（ P＜0．05），表明成功建立了AD细胞凋亡模型。 Western blot 结果显示，Aβ25-35药物处理组与空白组比较，Bcl-2表达明显减少，Bax表达明显增加。 Real-time PCR结果显示，不同浓度的Aβ25-35药物组与空白组比较，DNA甲基化酶DNMT1、DN-MT3a、DNMT3b、MeCP2表达无变化（ P＜0．05）；MSP结果显示空白对照组Bcl-2和Bax甲基化扩增阴性，非甲基化扩增阳性；Aβ25-35处理组Bcl-2和Bax甲基化引物扩增阴性，非甲基化引物扩增阳性。结论 MSP结果显示Aβ25-35介导SH-SY5Y细胞凋亡未引起Bcl-2、Bax启动子区甲基化的改变，

英文摘要：

Aim To investigate whether the effect of Aβ25-35 on Bcl-2 and Bax gene transcription through DNA methylation in SH-SY5Y cell.Methods Differ-ent concentrations of Aβ25-35 （0, 25, 50 μmol·L-1 ） were treated with SH-SY5Y cells for 48 h or 72 h in vitro.The optimal concentration and time of Aβ25-35 in-duced SH-SY5 Y apoptosis were determined by MTT method.Protein expression levels of Bcl-2 and Bax of Aβ25-35-treated groups were determined by Western blot.Real time PCR was used to detect the mRNA lev-els of DNA methyltransferase including DNMT 1 , DN-MT3a, DMT3b, MeCP2. Methylation specific PCR （ MSP） was used to analyze the effect of Aβ25-35 media-ted Bcl-2 and Bax gene promoter methylation .Results 25 μmol？ L-1 Aβ25-35 was exposed to SH-SY5Y cells for 72 h, MTT assay showed that cell viability was （68.49 ±9.83 ）%, which was significantly reduced compared with the control group （ P 〈0.05 ） , indica-ting AD cell apoptosis model was successfully estab-lished.Bcl-2 expression of Aβ25-35-treated group was significantly reduced compared with the control group , on the contrary , the expression of Bax was significantly increased .Real-time PCR results showed that com-pared with the control group , DNMT1, DNMT3a, DMT3b, MeCP2 mRNA levels of the Aβ25-35-treated groups had no significant difference （ P〉0.05 ）; MSP results showed that Bcl-2 and Bax unmethylated ampli-fication was positive , methylated amplification was neg-ative in control group , Bcl-2 and Bax unmethylated amplification was positive and methylated amplification was negative in Aβ25-35-treated group.Conclusion DNA methylation of Bcl-2 and Bax gene promoter are not affected during Aβ25-35 induced SH-SY5Y cell ap-optosis .