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New clearance system of abnormal protein in Polyglutammine disease

多聚谷氨酰胺病异常蛋白的新清除系统

基本信息

批准号：
13480258
负责人：
NAKAYAMA Keiichi
金额：
$ 9.66万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13480258/
关键词：
MJD UFD2 VPC polyglutamine Disease Ubiquitylation MJD1 ノックアウトマウス

项目摘要

Machado-Joseph disease (MJD)/Spinocerebellar ataxia type 3 (SCA3) is neurodegenerative disease which is caused by polyglutamine expansion in a responsible gene product, MJD1/Ataxin3. MJD1 has now been shown to undergo ubiquitylation and degradation by proteasome-dependent pathway. MJD1 with expanded polygiutamine tract was more resistant to degradation than normal MJD1. We established an in vitro system of ubiquitylation of MJD1, thereby biochemically purified activity to mediate polyubiquitylation of MJD1 from rabbit reticulocyte lysate. An AAA-family ATPase VCP was isolated from the active fraction, and found to binds to MJD1. Furthermore, UFD2a, a mammalian ubiquitin-chain assembly factor (E4), associated with VCP and induced polyubiquitylation of MJD1. UFD2a markedly promoted ubiquitylation and degradation of MJD1 with expanded polyglutamine tract, resulting in the clearance of MJD1 protein. In contrast, dominant-negative mutant UFD2a reduced the degradation rate of MJD1, leading to the formation of intracellular aggregation. In Drosophila model, overexpression of UFD2a significantly suppressed the neurodegeneration induced by expression of MJD1 with expanded polyglutamine tract. These findings suggest that E4 is a ratelimiting factor of degradation of pathologic polyglutamine-containing proteins, and may give a potential tool for gene therapy to control the clinical conditions of MJD

马查多-约瑟夫病(MJD)/脊髓小脑性共济失调3型(SCA3)是一种神经退行性疾病，由相关基因产物MJD1/Aaxin3的多谷氨酰胺扩张引起。目前研究表明，MJD1通过蛋白酶体依赖的途径发生泛素化和降解。扩增后的MJD1较正常MJD1具有更强的耐降解性。我们建立了MJD1泛素化的体外体系，从而生化纯化了介导兔网织红细胞裂解液中MJD1泛素化的活性。从活性部位中分离到一个AAA家族的ATPase VCP，并发现它与MJD1结合。此外，UFD2a是一种哺乳动物泛素链组装因子(E4)，与VCP相关并诱导MJD1的多泛素化。UFD2a能显著促进MJD1的泛素化和降解，使MJD1蛋白被清除。相反，显性-负性突变体UFD2a降低了MJD1的降解速度，导致细胞内聚集的形成。在果蝇模型中，UFD2a的过表达显著抑制了扩张的聚谷氨酰胺束表达MJD1所致的神经变性。这些发现表明，E4是病理性多谷氨酰胺蛋白降解的限速因子，可能为控制MJD临床状况的基因治疗提供一种潜在的工具。