线粒体外膜电压依赖阴离子通道在携带mtDNA A4263G突变的细胞株凋亡中的作用

Effect of voltage-dependent anion channel on apoptosis of cell lines carrying mitochondrial DNA A4263G mutation

目的:研究线粒体外膜电压依赖的阴离子通道(voltage-dependent anion channel,VDAC)在携带线粒体DNA(mitochondrial DNA,mtDNA)A4263G突变的细胞株凋亡中的作用。方法:对该家系的4名母系成员(3名血压异常者,1名血压正常者)和3名遗传背景相同的对照者建立了传代淋巴细胞系。采用流式细胞仪检测线粒体膜电势;用激光共聚焦显微镜观测VDAC与Bax蛋白结合的情况。结果:VDAC及凋亡相关蛋白Bax在携带mtDNAA4263G的细胞株中重表达增高,而淋巴细胞sKCa通道的表达没有明显差异;mtDNA A4263G突变携带者的线粒体膜电势与正常者比较平均降低32%(P<0.05);而加入环孢霉素A(CsA为VDAC拮抗剂)后,线粒体膜电势升高,与正常者之间的差异消失。携带突变者线粒体外膜的VDAC可与Bax蛋白结合,而正常对照者二者没有结合,在加入CsA后,可抑制突变者线粒体外膜VDAC与Bax蛋白的结合。结论:线粒体VDAC表达异常可导致mtDNAA4263G携带突变的细胞株凋亡增加。

AIM： To study the effect of voltage-dependent anion channel （VDAC） on apoptosis of cell lines carrying mitochondrial DNA A4263G mutation. METHODS： We established lymphoblastoid cell lines from three symptomatic and one asymptomatic individual in a family carrying A4263G mutation and we compared this with three control cell lines. Mitochondrial potential was detected by flow cytometry, and the combination of VDAC and Bax was evaluated by confocal images. RESULTS： Expression of VDAC and Bax in individuals carrying mtDNA A4263G mutation increased compared with those in the control group, whereas no changes were found in the expression of small conductance calcium-dependant potassium （sKCa）. Flow cytometry showed that mitochondrial potential （ΔΨm） of individuals carrying mtDNA A4263G mutation decreased 32% compared with the control group （P〈0.05） and this difference was attenuated by cyclosporin A （CsA）, a blocker of VDAC. Confocal images showed that VDAC was associated with Bax in individuals carrying mtDNA A4263G mutation, whereas the combination was not seen in the control group. CONCLUSION： Abnormality of mitochondrial VDAC leads to the significant increase of apoptosis of cell lines carrying mtDNA A4263G mutations.