目的：观察甜菜碱高半胱氨酸甲基转移酶(BHMT)在同型半胱氨酸(Hcy)环境下对人晶状体上皮细胞(HLEC)的保护作用。

方法：构建BHMT基因过表达慢病毒载体，将体外培养的HLEC随机分为3组：正常组：正常培养的HLEC； 对照组：感染了空载体的HLEC-B3，BHMT过表达组(OE)：感染了过表达BHMT基因载体的HLEC-B3，均培养于10% FBS(胎牛血清)培养基+5mmol/L Hcy培养液中。应用EdU(5-乙炔基-2'脱氧尿嘧啶核苷)试剂盒检测细胞的增殖能力，流式细胞仪检测活性氧(ROS)含量，可见分光光度计测算谷胱甘肽(GSH)活性，Western blotting检测内质网应激相关蛋白(GPR78，Nrf2)及凋亡相关酶Caspase-12的表达。

结果：BHMT过表达组较对照组细胞增殖能力增长约30.0%(P<0.05)。ROS检测显示，正常组、对照组、过表达组荧光强度分别为(89.2043±0.3511)%、(91.4502±0.0606)%、(49.5625±0.4502)%，过表达组与正常组有差异(P<0.05)； GSH活性检测显示：相比于正常组与对照组，BHMT高表达组GSH活性明显上升(P<0.05)； Western blotting结果显示：GRP78的相对表达量在正常组及对照组中明显高于过表达组，Nrf2的相对表达量在正常组与对照组中明显低于过表达组。凋亡相关酶Caspase-12的相对表达量在过表达组中明显低于对照组。

结论：BHMT可以抑制Hcy对HLEC的氧化损伤作用，降低ROS水平，升高GSH活性，减轻内质网应激反应，抑制细胞凋亡。BHMT对Hcy诱导的HLEC氧化损伤有重要的保护作用。

METHODS: HLEC were cultured in vitro and then randomly divided into 3 groups. Normal group:normal cultured HLEC; control group: normal cultured HLEC transfected with empty vector; BHMT gene overexpression group(OE): HLEC transfected with BHMT gene overexpression. All groups were cultured in 10% FCS DMEM +5mmol/L Hcy for 16h. After cultured, BHMT mRNA expression was measured by qRT-PCR and Western blot, the cell proliferation was detected by EdU Assay Kit,The level of ROS and GSH of HLEC were measured by Flow Cytometer and Visible Spectrophotometers. The expression level of of protein(GRP78, Nrf2, Caspase-12)was measured by western blotting.

RESULTS: After cultured 16h, cell proliferation ability in OE group was increased by 30.0% compared with NC group(P<0.05).The expression of ROS in normal group(89.2043±0.3511)% was obviously higher than OE group(49.5625±0.4502)%, P<0.05, GSH activity in OE group was obviously higher than control group and normal group,(P<0.05). The expression level of GRP78 in the normal group and the control group was significantly higher than overexpression group. The expression level of Nrf2 in the normal group and the control group was significantly lower than overexpression group. The expression level of Caspase-12 in the overexpression group was significantly lower than that in the control group.

CONCLUSION: BHMT in vitro can prevent the oxidative damage of HLEC by high homocysteine, clear the ROS and decrease the ER stress reaction. Apoptosis of lens epithelial cells was inhibited. BHMT plays an important protective role in oxidative damaged HLEC induced by Hcy.