SLC25A46 mutations cause optic atrophy, axonal neuropathy, and cerebellar neurodegeneration

 描述(申请人提供)：线粒体是动态细胞器，经历不断的融合和分裂。两个线粒体融合基因Mfn2和OPA1的突变分别导致重叠的神经退行性表型：轴索周围神经病和显性视神经萎缩。这一发现强调了线粒体动力学在防止神经退化方面的重要性。然而，我们对潜在的遗传和病理机制缺乏了解。我们提出的证据表明，SLC25A46突变会导致隐性遗传突变患者的视神经萎缩、轴突神经病变和其他临床特征。利用全外显子测序方法，我们在四个家系中发现了SLC25A46的突变。我们的结果表明，SLC25A46突变与线粒体的分裂和融合有关(《自然遗传学》，出版)。在这个项目中，我们建议使用小鼠模型和诱导的携带SLC25A46突变的多能干细胞(IPSC)系来研究其发病机制，并研究SLC25A46与OPA1的关系。首先，我们将对使用CRISPR技术创建的SLC25A46小鼠模型进行表征。具体地说，我们将通过视力准确性、视觉诱发电位、形态和眼底图像分析来评估视神经萎缩。我们还将通过组织学分析、运动功能、反射和感觉功能障碍来测试周围神经病。神经传导测量将用于确认周围神经病。此外，我们还将对目标组织进行线粒体功能测试。其次，使用我们创建的IPSC模型，我们将用我们最近建立的方案将IPSC系区分为视网膜神经节细胞 并研究SLC25A46突变如何影响视网膜神经节细胞分化过程。最后，我们的初步工作揭示了OPA1的复合杂合突变导致的表型与SLC25A46突变非常相似。我们将研究这两种蛋白质在线粒体融合和分裂中的作用。虽然基于该结构，SLC25A46被认为是线粒体载体，但其底物尚不清楚。我们未来的工作将包括使用动物和IPSC模型来鉴定底物和阐明SLC25A46的功能，从而开发治疗方法。这项研究将使我们了解与SLC25A46突变相关的发病机制，从而有助于开发潜在的治疗方法。

 DESCRIPTION (provided by applicant): Mitochondria are dynamic organelles that undergo constant fusion and fission. Mutations in two mitochondrial fusion genes, MFN2 and OPA1, cause overlapping neurodegenerative phenotypes: axonal peripheral neuropathy and dominant optic atrophy, respectively. This finding underscores the importance of mitochondrial dynamics in preventing nerve degeneration. However, our understanding of the underlying genetic and pathological mechanisms is lacking. We present evidence that SLC25A46 mutations cause optic atrophy, axonal neuropathy, and other clinical features in patients with recessively inherited mutations. Using whole-exome sequencing approaches, we identified mutations in SLC25A46 in four families. Our results showed that SLC25A46 mutations are associated with mitochondrial fission and fusion (Nature Genetics, in press). In this project, we propose to study pathogenesis using a mouse model and induced pluripotent stem cell (iPSC) lines carrying SLC25A46 mutations and examine the relationship between SLC25A46 and OPA1. Firstly, we will characterize the SLC25A46 mouse model, which was created with CRISPR technology. Specifically, we will evaluate optic atrophy with vision accuracy, visually evoked potentials, morphological and fundus images analysis. We will also test peripheral neuropathies by histological analysis, motor functions, reflexes, and sensory dysfunction. Nerve conduction measures will be used to confirm peripheral neuropathy. Furthermore, we will perform mitochondrial functional tests with the target tissues. Secondly, using our created iPSC model, we will differentiate iPSC lines into retinal ganglion cells with our recently established protocol and study how SLC25A46 mutations affect the process of retinal ganglion cell differentiation. Finally, our preliminary work revealed that compound heterozygous mutations of OPA1 cause very similar phenotypes to SLC25A46 mutations. We will investigate the relationship between these two proteins both functioning in mitochondrial fusion and fission. Although based on the structure, SLC25A46 is thought to be a mitochondrial carrier, its substrate is unknown. Our future work will involve using the animal and iPSC model to identify the substrate and to elucidate the functions of SLC25A46, therefore, to develop treatment. This study will allow us to understand the pathogenesis associated with SLC25A46 mutations, thereby aiding in the development of a potential treatment.