Institute for Stem Cell and Regenerative Medicine, University of Washington, School of Medicine, Seattle, WA, 98109, USA.
Department of Bioengineering, University of Washington, Seattle, WA, 98195, USA.
Nat Commun. 2019 Oct 11;10(1):4671. doi: 10.1038/s41467-019-12482-1.
Mitochondrial trifunctional protein deficiency, due to mutations in hydratase subunit A (HADHA), results in sudden infant death syndrome with no cure. To reveal the disease etiology, we generated stem cell-derived cardiomyocytes from HADHA-deficient hiPSCs and accelerated their maturation via an engineered microRNA maturation cocktail that upregulated the epigenetic regulator, HOPX. Here we report, matured HADHA mutant cardiomyocytes treated with an endogenous mixture of fatty acids manifest the disease phenotype: defective calcium dynamics and repolarization kinetics which results in a pro-arrhythmic state. Single cell RNA-seq reveals a cardiomyocyte developmental intermediate, based on metabolic gene expression. This intermediate gives rise to mature-like cardiomyocytes in control cells but, mutant cells transition to a pathological state with reduced fatty acid beta-oxidation, reduced mitochondrial proton gradient, disrupted cristae structure and defective cardiolipin remodeling. This study reveals that HADHA (tri-functional protein alpha), a monolysocardiolipin acyltransferase-like enzyme, is required for fatty acid beta-oxidation and cardiolipin remodeling, essential for functional mitochondria in human cardiomyocytes.
三功能蛋白缺乏症，由于脱水酶亚单位 A (HADHA) 的突变，导致婴儿猝死综合征，目前尚无治愈方法。为了揭示疾病的病因，我们从 HADHA 缺陷的 hiPSC 中生成了干细胞衍生的心肌细胞，并通过一种工程化的 microRNA 成熟鸡尾酒加速其成熟，该鸡尾酒上调了表观遗传调节剂 HOPX。在这里，我们报告说，用内源性脂肪酸混合物处理成熟的 HADHA 突变型心肌细胞会表现出疾病表型：钙动力学和复极化动力学缺陷，导致心律失常状态。单细胞 RNA-seq 揭示了基于代谢基因表达的心肌细胞发育中间状态。这种中间状态在对照细胞中产生成熟样心肌细胞，但突变细胞向病理状态转变，表现为脂肪酸β氧化减少、线粒体质子梯度降低、嵴结构破坏和心磷脂重塑缺陷。这项研究表明，HADHA（三功能蛋白α），一种单脂心磷脂酰基转移酶样酶，是脂肪酸β氧化和心磷脂重塑所必需的，对人类心肌细胞中功能性线粒体也是必需的。
