常染色体隐性遗传小脑性共济失调新的致病基因CAX的功能研究

项目名称： 常染色体隐性遗传小脑性共济失调新的致病基因CAX的功能研究

项目编号： No.81471295

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 医药、卫生

项目作者： 沈璐

作者单位： 中南大学

项目金额： 70万元

中文摘要： CAX基因是本课题组在前期工作中发现并克隆的常染色体隐性遗传小脑性共济失调新的候选致病基因，属于KLHL基因家族，功能尚不清楚，但该家族中多种基因均发现与神经系统遗传病相关，且参与形成Cul3-RING泛素连接酶复合体，调节重要底物蛋白降解的功能。前期工作中我们已证实该蛋白在小脑中高表达；功能预测提示在家系内发现的错义突变PNNX具有致病性；CAX与Cullin3存在相互作用，过表达CAX可抑制小脑颗粒细胞的轴突生长；提示CAX基因具有重要的生理功能并参与了遗传性共济失调的致病过程。本课题拟在此基础上，在细胞水平研究突变对CAX蛋白亚细胞定位、泛素蛋白酶体通路功能、神经元生长、蛋白相互作用等的影响；同时筛选和鉴定CAX蛋白的互作蛋白，进一步了解其生理功能；建立CAX基因敲除/敲入小鼠模型，从行为学、组织化学和病理生理学等多角度探讨CAX基因与ARCA致病性的关系，为揭示其发病机制研究提供新的线索。

中文关键词： 神经退行性疾病；发病机制；小脑性共济失调；致病基因；常染色体隐性遗传

英文摘要： Autosomal recessive cerebellar ataxias (ARCAs) are a group of neurodegenerative disorders that are characterized by complex clinical and genetic heterogeneity. We previously identified a novel ARCAs candidate gene, CAX, through exome sequencing and copy number variation (CNV) analysis in a two-generation ARCA family. CAX encodeing protein belongs to Kelch-like (KLHL) subfamily, which is implicated in ubiquitination by forming Cullin-RING E3 ligases complex and involved in the pathogenesis of several hereditary neurologic disorders. However, the function of this newly identified protein remaines unknown. In our previous work, we identified that CAX was highly expressed in cerebellum and interacted with Cullin3. The mutant residue PNNL was predicted to have a functional impact by SIFT and PolyPhen-2. Moreover, the over-expression of CAX caused abnormal axon morphology in cerebellum granule cell. Taken together, these results demonstrate that CAX may be a putative substrate adaptor for Cul3-RL that functions as a neurological specific ubiquitin ligase, and play an important role in the pathogenesis of CAX-associated ARCA. In this research, we intend to clarify whether the mutatants impact its subcellular localization, protein interaction, abnormal neuronal growth and dysfuncrion of ubiquitin-proteasome system. In addition, mass spectrum screening assay will used to seek its interacting proteins, CAX knockout mouse model will set-up to detect its behavior, histochemistry and pathophysiology alterations. All these might help us to understand the physiological function of CAX and reveal the association of CAX mutation and ARCA, and provide new clues of pathologenesis of ARCAs.

英文关键词： neurodegenerative disorders;pathogenesis;cerebellar ataxia;disease-causing gene;autosomal recessive