增殖抑制基因诱导血管平滑肌细胞凋亡

目的:研究增殖抑制基因(hyperplasia suppressor gene,HSG)诱导血管平滑肌细胞凋亡的作用,探讨其可能的机制.方法:采用重组复制缺陷型腺病毒载体携带大鼠HSG基因,转染培养的大鼠主动脉平滑肌细胞后,通过荧光染色检测细胞核的完整性,用流式细胞术检测细胞DNA含量的变化,用测定caspase-3活性等方法评价过表达HSG对细胞凋亡的作用;进行Western印迹检测过表达HSG对凋亡信号通路相关蛋白表达的影响.结果:用流式细胞术和细胞核染色结果显示过表达HSG能诱导血管平滑肌细胞凋亡,与对照组相比,流式细胞术检测到过表达HSG 72 h显著增加亚二倍体细胞百分率(39.6%±3.2% vs. 2.6%±0.9%,P＜ 0.01).测定细胞内caspase-3活性发现,与对照组相比,过表达HSG能增高caspase-3活性(0.354±0.104 vs. 0.064±0.022,P＜0.01).Western印迹显示HSG能增加细胞色素c的释放和下调Bcl-2的表达(0.26 ± 0.03 vs. 1.06±0.07,P＜0.01).结论:HSG通过影响Bcl-2/Bax的表达,促进细胞色素c的释放继而激活caspase-3诱导血管平滑肌细胞凋亡,活化线粒体途径可能是其诱导凋亡的机制之一.

Hyperplasia suppressor gene induces vascular smooth muscle cell apoptosis

OBJECTIVE: To study the effect of hyperplasia suppressor gene (HSG) in inducing vascular smooth muscle cell apoptosis and the underlying mechanisms. METHODS: The cultured VSMCs were transfected with an adenoviral vector containing rat HSG gene. Effects of HSG on VSMC apoptosis were investigated by fluorescent dye staining to detect the tact of nuclei, and by flow cytometry to define the content of DNA and to detect the levels of caspase-3. The expressions of Bcl-2 and Bax were also performed by Western blot analysis. RESULTS: The increased expression of HSG in VSMCs infected with AdHSG induced apoptotic cell death detected by flow cytometry assay and nucleic staining. Compared with control groups, HSG induced vascular smooth muscle cell apoptosis 72 h after infected with adenoviral vector (39.6%+/-3.2% vs. 2.6%+/-0.9%, P< 0.01). Overexpression of HSG also increased the activity of caspase-3 (0.354+/-0.104 vs. 0.064+/-0.022,P<0.01)and the release of cytochrome c. The Bcl-2 protein level was decreased ( 0.26+/-0.03 vs. 1.06+/-0.07,P<0.01)in AdHSG infected cells.CONCLUSION: Hyperplasia induced vascular smooth muscle cell apoptosis. HSG downregulated the expression of Bcl-2/Bax and activated caspase-3, and therefore promoted the release of cytochrome c and induced cell apoptosis.