The Pathogenic Mechanism of C19orf12 in Mitochondrial Membrane Protein Associated Neurodegeneration

摘要 脑神经变性伴铁蓄积（NBIA）定义了一组罕见的遗传性疾病， 铁沉积和神经系统中相关神经元损失的突出特征。虽然显著 遗传学研究的进展揭示了线粒体功能障碍在发病机制中的重要作用 NBIA的线粒体异常和金属失调的潜在机制仍然存在， 难以捉摸在这方面，我们重点研究了线粒体膜蛋白与铁积累的关系 （MPAN）是由C19orf12基因突变引起的，C19orf12是一种功能未知的蛋白质。试点 在这项研究中，我们分析了MPAN病例的人类活检、小鼠脑组织和人类神经母细胞瘤M17细胞 用C19orf12基因敲除（KO）的细胞系来研究C19orf12在MPAN线粒体中的作用， 正常的线粒体的确，我们对MPAN脑活检影像学研究的初步数据 条件表明，线粒体在存活的神经元中受损，这强调了 线粒体功能障碍。C19orf12在体内的探索表明， C19orf12在小鼠脑组织中的定位和蛋白表达。重要的是，我们发现C19orf12是 与线粒体复合物IV的电子传递链在体内。C19orf12的体外研究， C19orf12 KO M17细胞的线粒体呼吸分析显示线粒体氧受损 体外消耗。此外，微量金属分析表明，铁和铜的失调， C19orf12 KO细胞的线粒体。总之，这些令人兴奋的数据表明， C19orf12在线粒体中的功能与金属调节在生理条件下的作用及可能相关 C19orf12在MPAN发病过程中的紊乱。因此，进一步研究探讨 MPAN中的金属调节机制以及C19orf12突变体如何损害线粒体功能， 有正当理由目前的应用将阐明C19orf12的新机制，即连接 线粒体功能障碍和金属失调的MPAN病理。

Abstract Neurodegeneration in brain with iron accumulation (NBIA) defines a group of rare hereditary diseases with prominent features of iron deposition and related neuronal loss in the nervous system. Although significant progress in the genetic studies uncovered the essential role of mitochondrial dysfunction in the pathogenesis of NBIA, the underlying mechanism of mitochondrial abnormality and metal dysregulation in NBIA remains elusive. In this regard, we focused on the mitochondrial membrane proteins associated iron accumulation (MPAN) that was caused by genetic mutations in C19orf12, a protein with unknown function. In the pilot study, we analyzed human biopsy of an MPAN case, mouse brain tissue and human neuroblastoma M17 cell lines with C19orf12 knock-out (KO) to explore the role of C19orf12 in the mitochondria of MPAN and also in the normal mitochondria. Indeed, our preliminary data of imaging investigation on brain biopsy of MPAN conditions suggested mitochondria are impaired in the surviving neurons, which underscored the mitochondrial dysfunction in MPAN. The exploration of C19orf12 in vivo showed the mitochondrial localization and protein expression of C19orf12 in mouse brain tissues. Importantly, we found that C19orf12 is associated with mitochondrial complex IV of the electron transfer chain in vivo. In vitro study of C19orf12, mitochondrial respiration analysis of C19orf12 KO M17 cells showed impaired mitochondrial oxygen consumption in vitro. Furthermore, trace metal analysis showed both iron and copper dysregulation in the mitochondria of C19orf12 KO cells. Taken together, this exciting data demonstrated that the critical role of C19orf12 in mitochondrial function and metal regulation in the physiological condition and the likely related disturbance of C19orf12 during the pathogenesis of MPAN. Therefore, the further study to explore the mechanism of metal regulation in MPAN and how C19orf12 mutants impair mitochondrial function is warranted. The current application will shed light on the novel mechanism of C19orf12 that is linking mitochondrial dysfunction and metal dysregulation in the MPAN pathology.