College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Japan.
Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Chiba 263-8555, Japan.
Int J Mol Sci. 2023 Jan 17;24(3):1833. doi: 10.3390/ijms24031833.
Irreversible cell-cycle-arrested cells not undergoing cell divisions have been thought to be metabolically less active because of the unnecessary consumption of energy for cell division. On the other hand, they might be actively involved in the tissue microenvironment through an inflammatory response. In this study, we examined the mitochondria-dependent metabolism in human cells irreversibly arrested in response to ionizing radiation to confirm this possibility. Human primary WI-38 fibroblast cells and the BJ-5ta fibroblast-like cell line were exposed to 20 Gy X-rays and cultured for up to 9 days after irradiation. The mitochondrial morphology and membrane potential were evaluated in the cells using the mitochondrial-specific fluorescent reagents MitoTracker Green (MTG) and 5,5',6,6'-tetraethyl-benzimidazolylcarbocyanine iodide (JC-1), respectively. The ratio of the mean MTG-stained total mitochondrial area per unit cell area decreased for up to 9 days after X-irradiation. The fraction of the high mitochondrial membrane potential area visualized by JC-1 staining reached its minimum 2 days after irradiation and then increased (particularly, WI-38 cells increased 1.8-fold the value of the control). Their chronological changes indicate that the mitochondrial volume in the irreversible cell-cycle-arrested cells showed significant increase concurrently with cellular volume expansion, indicating that the mitochondria-dependent energy metabolism was still active. These results indicate that the energy metabolism in X-ray-induced senescent-like cells is active compared to nonirradiated normal cells, even though they do not undergo cell divisions.
不可逆细胞周期停滞的细胞由于不需要进行细胞分裂，因此被认为代谢活动较低。另一方面，它们可能通过炎症反应积极参与组织微环境。在这项研究中，我们检测了人类细胞在受到电离辐射后不可逆细胞周期停滞时，线粒体依赖性代谢的变化，以证实这一可能性。我们用 20Gy 的 X 射线照射人原代 WI-38 成纤维细胞和 BJ-5ta 成纤维样细胞系，然后在照射后继续培养最多 9 天。我们使用线粒体特异性荧光试剂 MitoTracker Green（MTG）和 5,5',6,6'-四乙基苯并咪唑羰花青碘化物（JC-1）分别评估细胞中的线粒体形态和膜电位。X 射线照射后，MTG 染色的总线粒体面积与单位细胞面积的比值最多在 9 天内持续下降。JC-1 染色显示的高线粒体膜电位区域的分数在照射后 2 天达到最小值，然后增加（特别是 WI-38 细胞增加了对照值的 1.8 倍）。它们的时间变化表明，不可逆细胞周期停滞的细胞中的线粒体体积随着细胞体积的扩大而显著增加，这表明线粒体依赖的能量代谢仍然活跃。这些结果表明，与未照射的正常细胞相比，X 射线诱导的衰老样细胞中的能量代谢是活跃的，即使它们不进行细胞分裂。
