Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
Department of Biochemistry and Biophysics, University of California San Francisco, USA.
Brain. 2020 Dec 5;143(11):3352-3373. doi: 10.1093/brain/awaa279.
Parkinson's disease is a neurodegenerative disorder with a multifactorial aetiology. Nevertheless, the genetic predisposition in many families with multi-incidence disease remains unknown. This study aimed to identify novel genes that cause familial Parkinson's disease. Whole exome sequencing was performed in three affected members of the index family with a late-onset autosomal-dominant parkinsonism and polyneuropathy. We identified a novel heterozygous substitution c.941A>C (p.Tyr314Ser) in the mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) gene, which co-segregates with disease within the family. Additional analysis of 699 unrelated Parkinson's disease probands with autosomal-dominant Parkinson's disease and 1934 patients with sporadic Parkinson's disease revealed another two variants in UQCRC1 in the probands with familial Parkinson's disease, c.931A>C (p.Ile311Leu) and an allele with concomitant splicing mutation (c.70-1G>A) and a frameshift insertion (c.73_74insG, p.Ala25Glyfs*27). All substitutions were absent in 1077 controls and the Taiwan Biobank exome database from healthy participants (n = 1517 exomes). We then assayed the pathogenicity of the identified rare variants using CRISPR/Cas9-based knock-in human dopaminergic SH-SY5Y cell lines, Drosophila and mouse models. Mutant UQCRC1 expression leads to neurite degeneration and mitochondrial respiratory chain dysfunction in SH-SY5Y cells. UQCRC1 p.Tyr314Ser knock-in Drosophila and mouse models exhibit age-dependent locomotor defects, dopaminergic neuronal loss, peripheral neuropathy, impaired respiratory chain complex III activity and aberrant mitochondrial ultrastructures in nigral neurons. Furthermore, intraperitoneal injection of levodopa could significantly improve the motor dysfunction in UQCRC1 p.Tyr314Ser mutant knock-in mice. Taken together, our in vitro and in vivo studies support the functional pathogenicity of rare UQCRC1 variants in familial parkinsonism. Our findings expand an additional link of mitochondrial complex III dysfunction in Parkinson's disease.
帕金森病是一种具有多因素病因的神经退行性疾病。然而,许多具有多发病例的家族的遗传易感性仍然未知。本研究旨在鉴定导致家族性帕金森病的新基因。对一个具有迟发性常染色体显性帕金森病和多发性神经病的索引家族的 3 名受影响成员进行了全外显子组测序。我们在核呼吸因子 1 基因(NRF1)中发现了一个新的杂合替代 c.941A>C(p.Tyr314Ser),该替代与家族内的疾病共分离。对 699 名具有常染色体显性帕金森病的无关帕金森病患者和 1934 名散发性帕金森病患者的进一步分析显示,在家族性帕金森病患者中,UQCRC1 中还存在另外两种变体,c.931A>C(p.Ile311Leu)和一个伴有剪接突变的等位基因(c.70-1G>A)和一个框移插入(c.73_74insG,p.Ala25Glyfs*27)。所有替代均不存在于 1077 名对照和来自健康参与者的台湾生物库外显子组数据库(n=1517 个外显子)中。然后,我们使用基于 CRISPR/Cas9 的敲入人多巴胺能 SH-SY5Y 细胞系、果蝇和小鼠模型来检测鉴定的罕见变体的致病性。突变 UQCRC1 表达导致 SH-SY5Y 细胞中的轴突退化和线粒体呼吸链功能障碍。UQCRC1 p.Tyr314Ser 敲入果蝇和小鼠模型表现出年龄依赖性运动缺陷、多巴胺能神经元丢失、周围神经病、呼吸链复合物 III 活性受损和黑质神经元中线粒体超微结构异常。此外,UQCRC1 p.Tyr314Ser 突变敲入小鼠的腹腔内注射左旋多巴可显著改善运动功能障碍。总之,我们的体外和体内研究支持家族性帕金森病中罕见 UQCRC1 变体的功能致病性。我们的发现扩展了帕金森病中线粒体复合物 III 功能障碍的另一个联系。