Department of Life Science, University of Seoul, Dongdaemun-Gu, Seoul 02504, Korea.
Cells. 2018 Dec 27;8(1):11. doi: 10.3390/cells8010011.
Glucose withdrawal has been used as a model for the study of homeostatic defense mechanisms, especially for how cells cope with a shortage of nutrient supply by enhancing catabolism. However, detailed cellular responses to glucose withdrawal have been poorly studied, and are controversial. In this study, we determined how glucose withdrawal affects mitochondrial activity, and the quantity and the role of SIRT1 in these changes. The results of our study indicate a substantial increase in ATP production from mitochondria, through an elevation of mitochondrial biogenesis, mediated by SIRT1 activation that is driven by increased NAD⁺/NADH ratio. Moreover, mitochondria persisted in the cells as elongated forms, and apparently evaded mitophagic removal. This led to a steady increase in mitochondria content and the reactive oxygen species (ROS) generated from them, indicating failure in ATP and ROS homeostasis, due to a misbalance in SIRT1-mediated mitochondria turnover in conditions of glucose withdrawal. Our results suggest that SIRT1 activation alone cannot properly manage energy homeostasis under certain metabolic crisis conditions.
葡萄糖耗竭已被用作研究体内平衡防御机制的模型,尤其是用于研究细胞如何通过增强分解代谢来应对营养供应短缺的问题。然而,葡萄糖耗竭对细胞的详细影响仍研究不足,并且存在争议。在这项研究中,我们确定了葡萄糖耗竭如何影响线粒体活性,以及 SIRT1 在这些变化中的数量和作用。我们的研究结果表明,通过 SIRT1 激活介导的线粒体生物发生的增加,导致 NAD⁺/NADH 比例的升高,从而从线粒体中产生大量的 ATP。此外,线粒体在细胞中保持为伸长的形式,并且显然逃避了线粒体自噬去除。这导致线粒体含量的稳定增加以及由此产生的活性氧(ROS)增加,表明由于葡萄糖耗竭条件下 SIRT1 介导的线粒体周转率失衡,导致 ATP 和 ROS 稳态的失败。我们的结果表明,在某些代谢危机条件下,仅激活 SIRT1 不能正确管理能量稳态。