Analysis of Torsin Protein Function in C. elegans

描述(由申请人提供)： 据估计，肌张力障碍的患病率是亨廷顿病、肌萎缩侧索硬化症或肌营养不良症的六倍。然而，在北美估计受影响的350,000多人中，只有5%的人得到了正确的诊断并正在接受治疗(NIH预算办公室)。这种疾病最严重的早发形式与人类基因TOR1A的突变有关，该基因编码TorsinA，这种蛋白质也定位于帕金森患者大脑中的包涵体，称为路易小体。虽然已发现致病基因突变，但肌张力障碍发病的细胞机制仍不清楚。我们正在应用模式生物秀丽线虫的优势，详细分析这种线虫中两个特定的扭蛋白相关基因产物。这些基因的染色体定位表明，它们可能代表着一个功能共表达的单位，我们实验室的初步研究表明，它们的作用是神经元的。Torsin家族的系统发育分析表明，这些蛋白与功能不同的AAA+蛋白家族有很远的序列相似性。我们已经确定，异位过表达线虫Torsin同源物导致多谷氨酰胺重复诱导的蛋白质聚集减少，其方式类似于先前报道的分子伴侣。随着动物年龄的增长，扭蛋白过度表达的抑制作用持续存在。用TOR-2特异性抗血清对转基因动物进行抗体染色，结果表明该蛋白高度定位于蛋白质聚集部位。我们建议通过组合反向遗传方法来扩展这些初步研究，这些方法旨在研究Torsin蛋白在线虫中的细胞作用。该项目的具体目标包括：1)确定哪些表型与线虫扭转蛋白同源物相关；2)确定线虫扭转蛋白的功能位点；以及3)确定扭转酶活性的潜在效应因子。这些研究将进一步加深我们对早发性扭转肌张力障碍的分子机制的理解。此外，与帕金森氏病等多种神经退行性疾病和亨廷顿病等多谷氨酰胺扩张引起的神经退行性疾病相关的异常蛋白质沉积值得进一步研究Torsins的任何假定的神经保护作用。

DESCRIPTION (provided by applicant): Dystonia is estimated to be six times more prevalent than Huntington's Disease, ALS, or Muscular Dystrophy. However, as few as 5% of the over 350,000 persons in North America estimated to be affected have been correctly diagnosed and are under treatment (NIH Budget Office). The most severe early-onset form of this disorder has been linked to a mutation in a human gene named TOR1A that encodes torsinA, a protein that is also localized to inclusions in the brains of Parkinson's patients termed Lewy bodies. While a causative genetic mutation has been identified, the cellular mechanisms of pathogenesis underlying dystonia remain unknown. We are applying the advantages of the model organism, Caenorhabditis elegans, towards a detailed analysis of two specific torsin-related gene products in this nematode. The chromosomal positioning of these genes suggests that they may represent a functionally co-expressed unit and preliminary studies from our laboratory indicate they act neuronally. Phylogenetic analysis of the torsin family indicates these proteins share distant sequence similarity with the functionally diverse AAA+ family of proteins. We have determined that ectopic overexpression of a C. elegans torsin homolog results in a reduction of polyglutamine repeat-induced protein aggregation in a manner similar to that previously reported for molecular chaperones. The suppressive effects of torsin overexpression quantitatively persisted as animals aged. Antibody staining of transgenic animals using antisera specific to TOR-2 indicated this protein was highly localized to sites of protein aggregation. We propose to extend these preliminary studies through a combination of reverse genetic approaches designed to investigate the cellular role of torsin proteins in the nematode. The specific aims of the proposed project include: 1) to determine what phenotypes are associated with C. elegans torsin homologues; 2) to define sites of C. elegans torsin protein function; and 3) to determine potential effectors of torsin activity. These studies will further our understanding of the molecular mechanisms responsible for early-onset torsion dystonia. Moreover, the aberrant protein deposition associated with diverse neurodegenerative disorders like Parkinson's Disease and those caused by polyglutamine expansion such as Huntington's Disease warrants further investigation of any putative neuroprotective effects of torsins.