同型半胱氨酸诱导内皮细胞凋亡及叶酸的拮抗机制———Caspase3及其抑制蛋白c-IAP1和c-IAP2的作用

Homocysteine-induced apoptosis of endothelial cells and its antagonism by folic acid——the roles of caspase3, c-IAP1 and c-IAP2

目的 本研究探讨同型半胱氨酸 (Hcy)致内皮细胞凋亡的途径以及叶酸拮抗Hcy的机制。方法 Hcy、叶酸或二者联合处理人脐静脉内皮细胞 (HUVEC) 2 4小时后 ,用AnnxinV染色加流式细胞术及基因组DNA电泳检测DNAladder了解细胞凋亡状态 ;RT PCR和蛋白质印迹技术检测caspase3、c IAP1和c IAP2的mRNA和蛋白质水平。结果 0 3mmol L和 3 0mmol L的Hcy均导致HUVEC凋亡 ,Hcy浓度高时凋亡细胞数较高 ,并伴有caspase3表达和活化增强 ,以及c IAP2的mRNA和蛋白质水平降低 ;叶酸可上调c IAP2的表达。结论 Hcy诱导HUVEC凋亡 ,此种作用可能涉及caspase3相关途径。叶酸可促进c IAP 2表达 ,从而部分拮抗Hcy的作用。

Objective The present study addresses the question how Hcy induces endothelial apoptosis and how folic acid antagonizes the proapoptotic effects of Hcy. Methods Human umbilical vein endothelial cells (HUVEC) were treated with Hcy, with or without folic acid, for 24 hours. Cell apoptosis was evaluated by Annexin V staining and flow cytometery, as well as agarose gel analysis for genomic DNA ladder. The mRNA and protein levels of caspase3, c-IAP1, and c-IAP2 were analyzed by RT-PCR and Western blot, respectively. Results Treatment with both low (0.3mmol/L) and high (3.0mmol/L) concentrations of Hcy induced HUVEC apoptosis, with higher apoptotic rate at the latter case. Hcy-induced HUVEC apoptosis was accompanied by an increased level of caspase3 expression and activation, together with decreased c-IAP2 level. Folic acid upregulated c-IAP2 expression while attenuating Hcy-induced apoptosis and caspase3 activation. Conclusion Hcy may induce HUVEC apoptosis via a pathway involving caspase3, which can be partially antagonized by folic acid, possibly through upregulated c-IAP2 expression.