亚砷酸钠对人正常肝细胞线粒体功能及SIRT1/PGC-1α通路相关蛋白表达的影响

Effects of sodium arsenite on mitochondrial function and expression of SIRT1/PGC-1αpathwayrelated proteins in human normal liver cell

[背景]长期砷暴露可引起不同程度的肝损伤,线粒体损伤可能是砷致肝损伤的早期关键事件,沉默信息调节因子2(sir2)相关酶1(SIRT1)/过氧化物酶体增殖物受体辅助激活因子-1α(PGC-1α)是调控线粒体质量和功能的重要通路,而砷所致肝损伤是否与SIRT1/PGC-1α通路介导的线粒体功能障碍有关目前尚不清楚。[目的]探讨亚砷酸钠(NaAsO2)对人正常肝细胞线粒体功能及SIRT1/PGC-1α通路相关蛋白表达的影响及机制。[方法]以人正常肝细胞(MIHA细胞)为研究对象,分别以不同浓度的NaAsO2(0、5、10、20μmoI·L^(-1))处理MIHA细胞24 h后收集细胞进行研究。采用透射电镜观察线粒体超微结构,荧光法检测三磷酸腺苷(ATP)浓度,流式细胞术检测线粒体膜电位(MMP)水平,免疫印迹法检测SIRT1、PGC-1α及其下游核呼吸因子1(NRF1)抗体、线粒体转录因子A(TFAM)蛋白表达水平。采用单因素方差分析及趋势性检验进行数据统计分析。[结果]MIHA细胞活力随NaAsO2浓度的升高逐渐降低(F=6495.47,P<0.001)。透射电镜结果显示10μmol·L^(-1)NaAsO2处理组线粒体大小不一、肿胀或伸长呈棒状,20μmol·L^(-1)NaAsO2处理组线粒体肿胀呈气球状或空泡状。MIHA细胞ATP浓度及MMP水平均随NaAsO2浓度的升高逐渐降低(FATP趋势=172.28,FMMP趋势=59.91;均P<0.001)。与对照组相比,5μmoI·L^(-1)NaAsO2处理组SIRT1、PGC-1α、NRF1及TFAM蛋白表达水平均无明显变化,但10μmol·L^(-1)NaAsO2处理组SIRT1、PGC-1α及TFAM蛋白表达水平降低(P<0.05),20μmol·L^(-1)NaAsO2处理组SIRT1、PGC-1α及NRF1蛋白表达水平降低(P<0.05);趋势性检验结果显示,SIRT1、PGC-1α、NRF1及TFAM蛋白表达水平均随NaAsO2浓度的升高逐渐降低(FSIRT1趋势=47.07,P<0.001;FPGC-1α趋势=15.17,P<0.01;FNRF1趋势=13.54,P<0.01;FTFAM趋势=4.20,P<0.05)。[结论]SIRT1/PGC-1α及其下游NRF1和TFAM的表达下调可能参与了NaAsO2诱导肝细胞线粒体功能障碍。

[Background]Long-term exposure to arsenic can cause liver injury of varying degrees.Mitochondrial damage may be an early key event of arsenic-induced liver injury.Silent mating type information regulation 2 homolog 1(SIRT1)/recombinant peroxisome proliferators-activated receptor gamma coactivator 1 alpha(PGC-1α)is an important pathway regulating mitochondrial mass and function.However,whether arsenic-induced liver injury is related to mitochondrial dysfunction mediated by SIRT1/PGC-1αpathway remains unclear.[Objective]To investigate potential effects of sodium arsenite(NaAsO2)on mitochondrial function and expressions of SIRT1/PGC-1αpathway-related proteins in human normal liver cell.[Methods]Human normal liver cells(MIHA cells)were used as the research object.MIHA cells were treated with different concentrations of NaAsO2(0,5,10 and 20μmol·L^(-1))for 24 h,and the cells were collected for study.The ultrastructure of mitochondria was observed by transmission electron microscopy,adenosine triphosphate(ATP)concentration by fluorescence method,mitochondrial membrane potential(MMP)level by flow cytometry,and SIRT1,PGC-1αand their downstream nuclear respiratory factor 1(NRF1)and mitochondrial transcription factor A(TFAM)protein expression levels by Western blotting.One-way analysis of variance and trend test were used for data statistical analysis.[Results]The viability of MIHA cells decreased gradually with the increase of NaAsO2concentration(F=6495.47,P<0.001).The transmission electron microscope observation showed that the size of mitochondria in the 10μmol·L^(-1) NaAsO2treatment group was different,and the mitochondria we re swollen or elongated in a rod-like shape.The mitochondria in the 20μmol·-1NaAsO2treatment group swelled like air spheres or vacuoles.The ATP concentration and MMP level of MIHA cells gradually decreased with the increase of NaAsO2concentration(Ftrend of ATP=172.28,Ftrend of MMP=59.91,both Ps<0.001).Compared with the control group,the protein expression levels of SIRT1,PGC-1α,NRF1,and TFAM were not significantly changed in the 5μmol·L^(-1)NaAsO2treatment group,while the protein expression levels of SIRT1,PGC-1α,and TFAM were decreased in the 10μmol·L^(-1)NaAsO2treatment group,and the protein expression levels of SIRT1,PGC-1α,and NRF1 were decreased in the 20μmol·L^(-1)NaAsO2treatment group.The results of trend test showed that the protein expression levels of SIRT1,PGC-1α,NRF1,and TFAM decreased gradually with the increase of NaAsO2concentration(Ftrend of SIRT1=47.07,P<0.001;Ftrend of PGC-1α=15.17,P<0.01;Ftrend of NRF1=13.54,P<0.01;Ftrend of TFAM=4.20,P<0.05).[Conclusion]The down-regulation of SIRT1/PGC-1αand its downstream NRF1 and TFAM may be involved in NaAsO2-induced mitochondrial dysfunction in liver cells.