Vanderbilt University, Cell and Developmental Biology, Nashville, TN 37232, USA.
Vanderbilt University, Molecular Physiology and Biophysics, Nashville, TN 37232, USA.
J Cell Sci. 2023 Feb 1;136(3). doi: 10.1242/jcs.260370. Epub 2023 Feb 10.
Mitochondria and peroxisomes are dynamic signaling organelles that constantly undergo fission, driven by the large GTPase dynamin-related protein 1 (DRP1; encoded by DNM1L). Patients with de novo heterozygous missense mutations in DNM1L present with encephalopathy due to defective mitochondrial and peroxisomal fission (EMPF1) - a devastating neurodevelopmental disease with no effective treatment. To interrogate the mechanisms by which DRP1 mutations cause cellular dysfunction, we used human-derived fibroblasts from patients who present with EMPF1. In addition to elongated mitochondrial morphology and lack of fission, patient cells display lower coupling efficiency, increased proton leak and upregulation of glycolysis. Mitochondrial hyperfusion also results in aberrant cristae structure and hyperpolarized mitochondrial membrane potential. Peroxisomes show a severely elongated morphology in patient cells, which is associated with reduced respiration when cells are reliant on fatty acid oxidation. Metabolomic analyses revealed impaired methionine cycle and synthesis of pyrimidine nucleotides. Our study provides insight into the role of mitochondrial dynamics in cristae maintenance and the metabolic capacity of the cell, as well as the disease mechanism underlying EMPF1.
线粒体和过氧化物酶体是动态的信号细胞器，它们不断经历分裂，这是由大型 GTPase 相关蛋白 dynamin-1（DRP1；由 DNM1L 编码）驱动的。具有 DNM1L 从头杂合错义突变的患者由于线粒体和过氧化物酶体分裂缺陷（EMPF1）而出现脑病 - 这是一种具有破坏性的神经发育疾病，目前尚无有效治疗方法。为了研究 DRP1 突变导致细胞功能障碍的机制，我们使用来自表现出 EMPF1 的患者的人源性成纤维细胞进行研究。除了线粒体形态拉长和分裂缺乏外，患者细胞还显示出较低的偶联效率、质子泄漏增加和糖酵解上调。线粒体过度融合也导致嵴结构异常和线粒体膜电位超极化。过氧化物酶体在患者细胞中呈现严重拉长的形态，这与细胞依赖脂肪酸氧化时呼吸减少有关。代谢组学分析显示蛋氨酸循环和嘧啶核苷酸合成受损。我们的研究提供了对线粒体动力学在嵴维持和细胞代谢能力中的作用的深入了解，以及 EMPF1 背后的疾病机制。
