目的 通过靶向线粒体的氧化还原敏感绿色荧光蛋白探针(mt-roGFP2荧光探针)检测人肝癌HepG2细胞(以下称HepG2细胞)线粒体活性氧(ROS)水平动态变化,旨在为以线粒体ROS为靶标的肝癌化疗奠定基础.方法 采用无缝克隆技术构建pLenti-CMV-mt-roGFP2-PGK-puro慢病毒载体并测序鉴定.将慢病毒载体pLenti-CMV-mt-roGFP2-PGK-puro与包装质粒pVSVg、pRev和pGag-Pol共转染人肾上皮293T细胞,获得mt-roGFP2慢病毒颗粒,并检测病毒滴度.将制备好的mt-roGFP2慢病毒颗粒感染HepG2细胞,通过荧光显微镜和Western blotting法鉴定观察HepG2细胞roGFP表达情况.将对数生长期稳定表达mt-roGFP2的HepG2细胞(HepG2-mtroGFP2细胞)与MitoTracker线粒体荧光探针共温育,采用激光共聚焦显微镜观察mt-roGFP2荧光探针的亚细胞定位.取对数生长期HepG2-mt-roGFP2细胞先后经0.5 mmol/L过氧化氢(H2O2)和1 mmol/L二硫苏糖醇(DTT)处理,采用尼康A1R激光扫描共聚焦显微镜拍摄同一细胞,Image J软件分析荧光图片.结果 成功构建pLenti-CMV-mt-roGFP2-PGK-puro慢病毒载体.制备的mt-roGFP2慢病毒平均滴度为4.04×108 IU/mL.mt-roGFP2荧光探针稳定表达在HepG2细胞中,并正确靶向HepG2细胞线粒体,成功构建HepG2-mt-roGFP2细胞.外源性氧化剂H2O2的加入可导致HepG2-mt-roGFP2细胞线粒体ROS水平明显升高,其荧光比值(405 nm/488 nm)从1.19上升到3.98,加入还原剂DTT可使其荧光比值下降至1.25.结论 靶向线粒体的mt-roGFP2荧光探针能够实时动态、可逆地检测HepG2细胞线粒体ROS水平变化并实时成像.%Objective To detect the dynamic changes of mitochondrial ROS in human hepatoblastoma HepG2 cell line(hereafter called HepG2 cells) by mitochondria-targeted mt-roGFP2 biosensor, and to lay the foundation for the chemotherapy of liver cancer targeting mitochondrial ROS. Methods The lentivirus vector pLenti-CMV-mt-roGFP2-PGK-puro was constructed by seamless cloning technology, and was identified by DNA sequencing. The lentivirus mt-roGFP2 was prepared by co-transfecting the human embryonic kideny 293T cells with the lentivirus vector pLenti-CMV-mt-roGFP2-PGKpuro and packaging plasmids pVSVg, pRev, and pGag-Pol, and then its virus titer was tested. The expression of roGFP in the HepG2 cells infected by the prepared mt-roGFP2 lentivirus particles was analyzed through fluorescence microscope and Western blotting. The HepG2 cells expressing mt-roGFP2 (HepG2-mt-roGFP2 cells) in logarithmic growth phase were incubated with MitoTracker probe, and then the subcellular localization of mt-roGFP2 biosensor was investigated by confocal laser scanning microscopy. The HepG2-mt-roGFP2 cells in the logarithmic growth phase treated with 0. 5 mmol/L H2O2 and 1 mmol/L DTT were imaged by using Nikon A1R confocal laser scanning system, and the fluorescence images were exported to Image J software. Results The lentivirus vector pLenti-CMV-mt-roGFP2-PGK-puro was successfully constructed. The mean titer of mt-roGFP2 was 4. 04 × 108 IU/mL. roGFP biosencor was stably expressed in the HepG2 cells and correctly targeted to mitochondria, indicating the successful construction of HepG2-mt-roGFP2 cells. The addition of exogenous oxidant H2O2 led to a significant increase of mitochondrial ROS in the HepG2-mt-roGFP2 cells, with the 405 nm/488 nm fluorescence ratios ranging from 1. 19 to 3. 98, and the injection of reductant DTT declined the fluorescence ratio to 1. 25. Conclusion The mitochondria-targeted mt-roGFP2 biosensor can real-time and reversibly detect the changes of mitochondrial ROS in the HepG2 cells and display the real-time imaging.
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