目的：观察MicroRNA-34a对人晶状体上皮细胞系SRA01/04衰老和凋亡的影响及作用机制。

方法：qRT-PCR检测年龄相关性白内障(ARC)晶状体和透明晶状体上皮细胞中MicroRNA-34a表达水平，采用脂质体转染试剂盒将MicroRNA-34a mimics(过表达组)、MicroRNA-34a inhibitors(抑制组)和空脂质体(对照组)转染至SRA01/04细胞，qRT-PCR检测MicroRNA-34a的表达量； 采用β-半乳糖苷酸(SA-β-gal)染色检测转染后细胞的衰老情况。Annexin V-FITC/PI双染色流式细胞仪检测MicroRNA-34a对人晶状体细胞系SRA01/04细胞凋亡的影响； 蛋白免疫印迹检测Cdc42、Rac1蛋白的表达。

结果：透明晶状体前囊膜组织中MicroRNA-34a的表达量显著低于ARC晶状体前囊膜组织(P<0.05)； MicroRNA-34a过表达组、对照组、MicroRNA-34a抑制组SA-β-gal阳性率分别为(87.56±2.34)%、(12.22±2.74)%、(3.45±0.45)%。MicroRNA-34a过表达组明显高于对照组，而MicroRNA-34a抑制组SA-β-gal阳性率明显低于对照组(P<0.05)； MicroRNA-34a抑制组、对照组和MicroRNA-34a过表达组的细胞凋亡率分别为(5.87±1.22)%、(12.26±2.14)%、(29.45±3.12)%，MicroRNA-34a抑制组细胞凋亡率明显低于对照组，而MicroRNA-34a过表达组细胞凋亡率明显高于对照组(P<0.05)； MicroRNA-34a过表达组中Cdc42和Rac1的表达明显高于对照组(P<0.05)，MicroRNA-34a抑制组中Cdc42和Rac1的表达明显低于对照组(P<0.05)。

结论：MicroRNA-34a可能通过上调Cdc42和Rac1促进人晶状体上皮细胞衰老和凋亡。

METHODS: MicroRNA-34a expression levels in ARC lens and transparent lens epithelial cells were detected by qRT-PCR. MicroRNA-34a mimics, MicroRNA-34a inhibitors and empty liposome(control group)were transfected into SRA01/04 cells by liposome transfection kit. Annexin V-FITC/PI double staining was used to detect the effect of MicroRNA-34a on the apoptosis of human lens cell line SRA01/04. The expression of Cdc42 and Rac1 protein was detected by western blot.

RESULTS: The expression level of MicroRNA-34a in anterior capsular tissue of transparent lens was significantly lower than that in ARC anterior capsular tissue(P<0.05). The positive rates of SA-β-gal in the MicroRNA-34a mimics group, the control group and the MicroRNA-34a inhibitors group were(87.56±2.34)%,(12.22±2.74)% and(3.45±0.45)%, respectively. The positive rates of SA-β-gal in the MicroRNA-34a mimics group was significantly higher than the control group, while the SA-β-gal positive rate in the MicroRNA-34a inhibitors group was significantly lower than that in the control group(P<0.05). The apoptosis rate of the MicroRNA-34a inhibitors group, control group and MicroRNA-34a mimics group were(5.87±1.22)%,(12.26±2.14)% and(29.45±3.12)%, respectively. The apoptosis rate of the MicroRNA-34a mimics group was significantly higher than that of the control group, while that of the MicroRNA-34a inhibitors group was significantly lower than that of the control group(P<0.05). The expressions of Cdc42 and Rac1 in the MicroRNA-34a mimics group were significantly higher than those in the control group(P<0.05), while the expressions of Cdc42 and Rac1 in the MicroRNA-34a inhibitors group were significantly lower than those in the control group(P<0.05).

CONCLUSION: MicroRNA-34a may promote the senescence and apoptosis of human lens epithelial cells by up-regulating Cdc42 and Rac1.