Mitochondrial biogenesis is a cell response to external stimuli which is generally believed to suppress apoptosis. However, during the process of apoptosis, whether mitochondrial biogenesis occurs in the early stage of the apoptotic cells remains unclear. To address this question, we constructed the COX8-EGFP-ACTIN-mCherry HeLa cells with recombinant fluorescent proteins respectively tagged on the nucleus and mitochondria, and monitored the mitochondrial changes in living cells exposed to gamma-ray radiation. Besides in situ detection of mitochondrial fluorescence changes, we also examined the cell viability, nuclear DNA damage, reactive oxygen species (ROS), Mitochondrial superoxide, citrate synthase activity, ATP, cytoplasmic and mitochondrial calcium, mitochondrial DNA copy number and expression of transcription genes related to mitochondrial biogenesis as well as the apoptosis biomarkers. As a result, we confirmed that significant mitochondrial biogenesis took place preceding the radiation-induced apoptosis, and the change of mitochondrial biogenesis at early time was closely correlated with the apoptotic cells at late stage. The involved mechanism was also discussed.

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线粒体生物发生的原位观察作为细胞凋亡的早期事件

线粒体的生物发生是细胞对外部刺激的反应，通常认为它可以抑制细胞凋亡。然而，在凋亡过程中，线粒体的生物发生是否发生在凋亡细胞的早期尚不清楚。为了解决这个问题，我们构建了带有分别标记在细胞核和线粒体上的重组荧光蛋白的COX8-EGFP-ACTIN-mCherry HeLa细胞，并监测了暴露于伽马射线辐射的活细胞的线粒体变化。除了原位检测线粒体荧光变化外，我们还检查了细胞活力，核DNA损伤，活性氧（ROS），线粒体超氧化物，柠檬酸合酶活性，ATP，细胞质和线粒体钙，线粒体DNA的拷贝数和与线粒体生物发生以及凋亡生物标志物有关的转录基因的表达。结果，我们确认在辐射诱导的细胞凋亡之前发生了明显的线粒体生物发生，并且早期线粒体生物发生的变化与晚期的凋亡细胞密切相关。还讨论了涉及的机制。