Department of Translational Services, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; Integrated Physiology and Molecular Medicine Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
Integrated Physiology and Molecular Medicine Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.
J Biol Chem. 2021 Oct;297(4):101196. doi: 10.1016/j.jbc.2021.101196. Epub 2021 Sep 13.
Mitochondria undergo continuous cycles of fission and fusion to promote inheritance, regulate quality control, and mitigate organelle stress. More recently, this process of mitochondrial dynamics has been demonstrated to be highly sensitive to nutrient supply, ultimately conferring bioenergetic plasticity to the organelle. However, whether regulators of mitochondrial dynamics play a causative role in nutrient regulation remains unclear. In this study, we generated a cellular loss-of-function model for dynamin-related protein 1 (DRP1), the primary regulator of outer membrane mitochondrial fission. Loss of DRP1 (shDRP1) resulted in extensive ultrastructural and functional remodeling of mitochondria, characterized by pleomorphic enlargement, increased electron density of the matrix, and defective NADH and succinate oxidation. Despite increased mitochondrial size and volume, shDRP1 cells exhibited reduced cellular glucose uptake and mitochondrial fatty acid oxidation. Untargeted transcriptomic profiling revealed severe downregulation of genes required for cellular and mitochondrial calcium homeostasis, which was coupled to loss of ATP-stimulated calcium flux and impaired substrate oxidation stimulated by exogenous calcium. The insights obtained herein suggest that DRP1 regulates substrate oxidation by altering whole-cell and mitochondrial calcium dynamics. These findings are relevant to the targetability of mitochondrial fission and have clinical relevance in the identification of treatments for fission-related pathologies such as hereditary neuropathies, inborn errors in metabolism, cancer, and chronic diseases.
线粒体不断经历分裂和融合的循环，以促进遗传、调节质量控制和减轻细胞器压力。最近，这一线粒体动力学过程被证明对营养供应高度敏感，最终赋予细胞器生物能量的可塑性。然而，线粒体动力学的调节因子是否在营养调节中起因果作用仍不清楚。在这项研究中，我们生成了一种细胞缺失功能的动力相关蛋白 1（DRP1）模型，DRP1 是外膜线粒体分裂的主要调节因子。DRP1 的缺失（shDRP1）导致线粒体的广泛超微结构和功能重塑，表现为多形性增大、基质电子密度增加以及 NADH 和琥珀酸氧化缺陷。尽管线粒体的大小和体积增加，但 shDRP1 细胞的细胞葡萄糖摄取和线粒体脂肪酸氧化减少。非靶向转录组分析显示，细胞和线粒体钙稳态所需的基因严重下调，这与 ATP 刺激的钙流丧失以及外源性钙刺激的底物氧化受损有关。本文的研究结果表明，DRP1 通过改变细胞整体和线粒体钙动力学来调节底物氧化。这些发现与线粒体分裂的靶向性有关，并在鉴定与分裂相关的病理学（如遗传性神经病、先天性代谢错误、癌症和慢性疾病）的治疗方法方面具有临床意义。
