Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, USA.
Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA.
Sci Rep. 2021 Mar 23;11(1):6671. doi: 10.1038/s41598-021-85795-1.
The mitochondrion is one of the key organelles for maintaining cellular homeostasis. External environmental stimuli and internal regulatory processes may alter the metabolism and functions of mitochondria. To understand these activities of mitochondria, it is critical to probe the key metabolic molecules inside these organelles. In this study, we used label-free chemical imaging modalities including coherent anti-Stokes Raman scattering and multiphoton-excited fluorescence to investigate the mitochondrial activities in living cancer cells. We found that hypothermia exposure tends to induce fatty-acid (FA) accumulation in some mitochondria of MIAPaCa-2 cells. Autofluorescence images show that the FA-accumulated mitochondria also have abnormal metabolism of nicotinamide adenine dinucleotide hydrogen, likely induced by the dysfunction of the electron transport chain. We also found that when the cells were re-warmed to physiological temperature after a period of hypothermia, the FA-accumulated mitochondria changed their structural features. To the best of our knowledge, this is the first time that FA accumulation in mitochondria was observed in live cells. Our research also demonstrates that multimodal label-free chemical imaging is an attractive tool to discover abnormal functions of mitochondria at the single-organelle level and can be used to quantify the dynamic changes of these organelles under perturbative conditions.
线粒体是维持细胞内环境稳定的关键细胞器之一。外部环境刺激和内部调节过程可能会改变线粒体的代谢和功能。为了了解线粒体的这些活动，探究这些细胞器内的关键代谢分子是至关重要的。在这项研究中，我们使用了无标记化学成像技术，包括相干反斯托克斯拉曼散射和多光子激发荧光，来研究活癌细胞中线粒体的活性。我们发现，低温暴露往往会导致 MIAPaCa-2 细胞中的一些线粒体中脂肪酸（FA）的积累。自发荧光图像显示，FA 积累的线粒体也存在烟酰胺腺嘌呤二核苷酸氢的异常代谢，可能是由电子传递链功能障碍引起的。我们还发现，当细胞在一段时间的低温后被重新加热到生理温度时，FA 积累的线粒体改变了它们的结构特征。据我们所知，这是首次在活细胞中观察到线粒体中的 FA 积累。我们的研究还表明，多模态无标记化学成像技术是一种有吸引力的工具，可以在单细胞水平上发现线粒体的异常功能，并可用于量化这些细胞器在扰动条件下的动态变化。
