N-乙酰半胱氨酸对人脐静脉内皮细胞eNOS的保护作用

摘要

Objective To investigate the protective effects of N-Acetyl-cysteine(NAC) pretreatment on endothelial nitric oxide syn-thase(eNOS) activity in human umbilical vein endothelial cells(HUVECs), as well as its possible molecular mechanisms.Methods HU-VECs were randomly divided into control,AngⅡ,NAC pretreatment and NAC pretreatment+AngⅡgroups. The levels of eNOS,PP2A-Cα, I2PP2A protein expression and p-eNOS Ser1177,p-PP2A-c Y307 were measured by Western blot. The activity of constitutive NOS(cNOS) and the content of nitric oxide(NO) in cell culture medium were determined via chemical colorimetric methods.Results Compared with those of control group,the levels of p-eNOS Ser1177,p-PP2A-c Y307 and I2PP2A protein expression in AngⅡgroup were decreased significantly(p<0.05),the activity of cNOS and the content of NO in cell culture medium were decreased significantly (P<0.05). After NAC pretreat-ment,the changes were reversed.Conclusions NAC pretreatment decreases the activation of PP2A through the upregulating PP2A-c Y307 and I2PP2A,thus increasing the activity of eNOS in HUVECs.%目的 探讨N-乙酰半胱氨酸(NAC)预处理对人脐静脉内皮细胞(HUVECs)中内皮型一氧化氮合酶(eNOS)的保护作用及可能的分子机制.方法 HUVECs随机分为正常对照组、血管紧张素(Ang)Ⅱ组、单纯NAC组和NAC预处理+AngⅡ组.用Western印迹法检测eNOS蛋白、eNOS Ser1177磷酸化水平、蛋白磷酸酶(PP)2A-Cα、PP2A-c Y307磷酸化水平和I2PP2A表达水平,化学比色法检测细胞组成型一氧化氮合酶(cNOS)活性及培养基中一氧化氮(NO)含量.结果 AngⅡ刺激后eNOS Ser1177、PP2A-c Y307水平和I2PP2A表达水平降低(P<0.05),cNOS活性、NO含量均降低(P<0.05);NAC预处理后上述变化均被逆转.结论 NAC预处理可上调PP2A-c Y307和I2PP2A水平,从而降低PP2A活性,最终保护eNOS活性.