Mitochondrial deregulation has gained increasing support as a pathological mechanism in Huntington’s disease (HD), a genetic-based neurodegenerative disorder caused by CAG expansion in the HTT gene. In this study, we thoroughly investigated mitochondrial-based mechanisms in HD patient-derived iPSC (HD-iPSC) and differentiated neural stem cells (NSC) versus control cells, as well as in cells subjected to CRISPR/Cas9-CAG repeat deletion. We analyzed mitochondrial morphology, function and biogenesis, linked to exosomal release of mitochondrial components, glycolytic flux, ATP generation and cellular redox status. Mitochondria in HD cells exhibited round shape and fragmented morphology. Functionally, HD-iPSC and HD-NSC displayed lower mitochondrial respiration, exosomal release of cytochrome c, decreased ATP/ADP, reduced PGC-1α and complex III subunit expression and activity, and were highly dependent on glycolysis, supported by pyruvate dehydrogenase (PDH) inactivation. HD-iPSC and HD-NSC mitochondria showed ATP synthase reversal and increased calcium retention. Enhanced mitochondrial reactive oxygen species (ROS) were also observed in HD-iPSC and HD-NSC, along with decreased UCP2 mRNA levels. CRISPR/Cas9-CAG repeat deletion in HD-iPSC and derived HD-NSC ameliorated mitochondrial phenotypes. Data attests for intricate metabolic and mitochondrial dysfunction linked to transcriptional deregulation as early events in HD pathogenesis, which are alleviated following CAG deletion.

作为亨廷顿氏病（HD）的病理机制，线粒体失调已获得越来越多的支持，亨廷顿氏病（HD）是一种遗传性神经退行性疾病，由CAG扩展引起 HTT基因。在这项研究中，我们彻底研究了HD患者衍生的iPSC（HD-iPSC）和分化的神经干细胞（NSC）中基于线粒体的机制与对照细胞，以及经历CRISPR / Cas9-CAG重复缺失的细胞。我们分析了线粒体的形态，功能和生物发生，与线粒体成分的外泌体释放，糖酵解通量，ATP生成和细胞氧化还原状态有关。HD细胞中的线粒体表现出圆形和破碎的形态。在功能上，HD-iPSC和HD-NSC表现出较低的线粒体呼吸作用，细胞色素c的外泌体释放，ATP / ADP降低，PGC-1α和复合物III亚基的表达和活性降低，并且高度依赖于糖酵解，并由丙酮酸脱氢酶（PDH）支持）灭活。HD-iPSC和HD-NSC线粒体显示ATP合酶逆转并增加了钙保留。在HD-iPSC和HD-NSC中还观察到增强的线粒体活性氧（ROS），同时UCP2 mRNA水平降低。HD-iPSC中的CRISPR / Cas9-CAG重复缺失和衍生的HD-NSC改善了线粒体表型。数据证明与转录失调有关的复杂代谢和线粒体功能障碍是HD发病机制中的早期事件，在CAG缺失后可以缓解。