胱硫醚β-合酶/胱硫醚γ-裂解酶-硫化氢体系小干扰RNA对大鼠正常肝细胞株BRL凋亡的影响

Small Interfering RNA of Cystathionine β-Synthase/ Cystathionine γ-Lyase-Derived Hydrogen Sulfide Synthesis Induces Apoptosis of Rat Hepatic BRL Cell Line

目的：探讨内源性胱硫醚β-合酶（CBS）/胱硫醚γ-裂解酶（CSE）-硫化氢（H2S）体系在生理状态肝细胞凋亡中的作用及其机制。方法培养大鼠正常肝细胞株BRL。小干扰RNA（siRNA）序列筛选：设阴性siRNA序列转染组（对照组）、CBS siRNA序列转染组（CBS 1~3序列组）和CSE siRNA序列转染组（CSE 1~3序列组），转染24、48 h；siRNA转染后检测细胞凋亡：设阴性对照组、溶剂对照组、CBS siRNA组、CSE siRNA组、（CBS＋CSE）siRNA组，作用时间为转染后0、4、8、12、24 h；凋亡机制探讨：设阴性对照组、CBS siRNA组、CSE siRNA组、（CBS＋CSE）siRNA组，作用时间为转染后4、8、12、24 h；每组均4个平行样。RT-PCR、Western blot检测BRL细胞中CBS、CSE mRNA和蛋白的表达，siRNA基因静默CBS、CSE，去蛋白法检测H2S生成，Hoechst荧光染色、流式细胞术检测BRL细胞凋亡，荧光染色检测线粒体膜电位（MMP）变化，Western blot 检测胞浆内细胞色素 C（Cyt C）和激活型 caspase 3（cleaved-caspase 3）蛋白表达变化。结果 BRL细胞株存在CBS、CSE表达。CBS/CSE siRNA转染后，细胞内源性H2S生成降低，凋亡细胞数量和细胞凋亡率随时间延长而逐渐增加，BRL细胞上清乳酸脱氢酶（LDH）活性均未见明显变化，MMP下降，胞浆内Cyt C蛋白表达上调，cleaved-caspase3蛋白表达上调。结论抑制内源性H2S体系可引起生理状态肝细胞凋亡，机制可能部分涉及凋亡线粒体途径。

Objective To explore the inhibitory effects of endogenous hydrogen sulfide, a novel and important gas-eous transmitter generated in mammalian tissues mainly by cystathionine β-synthase （CBS） or cystathionineγ-lyase （CSE） on the apoptosis of the rat hepatic BRL cell line in physiological condition. Methods BRL cells were cultured, and divid-ed randomly into several groups in different phases of the experiment, including negative-siRNA （control） group, CBS siRNA （CBS 1~3） group and CSE siRNA （CSE 1~3） group, which were used to select the most efficient sequences of siRNAs at 48 or 24-hour transfection. Solution group and （CBS＋CSE） siRNA group were added to detect the variation of apoptosis. The BRL cell line was observed and evaluated at 0, 4, 8, 12, and 24 hrs after siRNA transfection. When the mechanisms of the apoptosis were detected, CBS/CSE siRNAs were transfected individually or jointly into BRL cells, and compared with nega-tive-siRNA group to examine the variation. The genic and protein expression of CBS/CSE were detected by RT-PCR and Western blot assay. After transfection of CBS/CSE siRNA, the apoptosis of BRL cells was detected by Hoechst stain and flow cytometry （FCM）. The mitochondrial membrane potential （MMP） changes were observed by fluorescent staining. Western blot assay was used to examine the protein expression of intracytoplasm cytochrome C （Cyt C） and cleaved-caspase 3. Re-sults CBS and CSE were observed in BRL cells. After transfection of CBS/CSE siRNA, endogenous H2S generation de-creased and the apoptosis of BRL cells increased. Accordingly, the expression of intracytoplasm-Cyt C and cleaved-caspase 3 increased. Conclusion The inhibition of endogenous H2S synthesis induced the apoptosis of BRL cells under physiologi-cal condition, which may be involved in mitochondrial pathway of apoptosis.