VPS13D调控溶酶体动态和功能在遗传性共济失调中的作用机制研究

The hereditary ataxia (HA) is a clinically and genetically heterogeneous group of inherited neurodegenerative disorders, account for 10-15% all neurologic genetic disease. Until now, molecular mechanisms of HA pathology are largely unclear. We previously identified, for the first time, VPS13D as a key regulator of mitochondrial functions, and its suppression led to severe mitochondrial defects in mammalian cells. Consistently, two recent clinical studies independently showed that VPS13D was a novel causative gene of HA, affected patients showed ataxia with spasticity, white matter atrophy and demyelination at brain MRI along with mitochondria defects in morphologies and distributions. By CRISPR-Cas9 mediated GFP knock-in and high-resolution live cell microscopy, we revealed that VPS13D localized to lysosomes and its suppression by specific siRNAs perturbed lysosomal dynamics, including lysosome number, size, distributions and transport. We further identified lysosomal proteins Rab7 and Lamp1 as interacting partners of VPS13D. Therefore, we hypothesized that VPS13D not only regulated mitochondrial functions but directly regulate lysosomal dynamics and functions. To prove our hypothesis, we are going to explore the roles of VPS13D in regulation of lysosomal dynamics and functions and illustrated the underlying mechanisms in both cellular and in vivo level, eventually shed light on how VPS13D loss of function contributes to HA pathogenesis.

遗传性共济失调（HA）是一类多基因致病的遗传性神经退行性疾病，其发病机理仍然未知。最新临床研究证实，VPS13D是HA的致病基因之一，患者细胞出现线粒体形态和分布异常，肌肉活检提示脂质沉积。本课题组近期首次在哺乳动物细胞中发现VPS13D是调控线粒体动态和功能的关键蛋白，其定位于溶酶体，并直接调控溶酶体的形态、大小和分布。此外，我们还发现VPS13D与溶酶体蛋白Rab7相结合。因此，我们提出假说认为VPS13D不仅调控线粒体功能，还直接调控溶酶体动态和功能，VPS13D基因突变导致溶酶体动力学及功能异常，可能是导致HA发病的分子基础。本研究将利用CRISRP-Cas9结合活细胞高分辨率成像技术，在细胞和转基因小鼠模型中，探索VPS13D调控溶酶体动态与功能的作用及机制，阐明VPS13D在HA发生发展中的重要作用。本研究将加深对VPS13D生理功能的理解，并为HA的诊疗提供新的理论依据。

遗传性共济失调（HA）是一类多基因致病的遗传性神经退行性疾病，其发病机理仍然未知。临床研究证实，VPS13D是HA的致病基因之一，患者细胞出现线粒体形态和分布异常，肌肉活检提示脂质沉积。本课题组近期首次在哺乳动物细胞中发现VPS13D是调控线粒体动态和功能的关键蛋白，主要聚集于线粒体和脂滴之间的膜接触位点，并直接调控线粒体和脂滴这两种重要细胞器的接触和相互作用。此外，我们还发现VPS13D与部分线粒体蛋白、内质网蛋白相互作用。VPS13D直接调控VAPB和PTPIP51在线粒体中的表达，这可能是VPS13D调控线粒体功能的机制之一。VPS13D还能够结合ESCRT蛋白TSG101，调控TSG101被招募至脂滴表面从而影响脂肪酸转运。因此，我们的研究成果显示VPS13D直接调控线粒体功能，并且参与线粒体和脂滴之间膜接触位点的形成和维持，VPS13D功能异常可能是导致HA发病的分子基础。本研究利用CRISRP-Cas9结合活细胞高分辨率成像技术，探索了VPS13D调控线粒体和溶酶体动态与功能的作用及机制，阐明了VPS13D在HA发生发展中的重要作用，并为HA诊疗提供新的理论依据。