FUNCTIONAL ANALYSIS OF TORSIN A

描述（由申请人提供）：早发性（DYT 1）扭转性肌张力障碍是一种破坏性非退行性神经运动障碍，由蛋白质torsinA（TOR 1A）中谷氨酸缺失的常染色体显性遗传引起，通常称为？是不是？E突变，因为密码子或氨基酸缺失。中枢神经系统异常的肌张力障碍是知之甚少，与功能成像和临床电生理学研究表明，在整个运动电路的一系列结构的异常。更具体的洞察力应该来自于对负责任的遗传变化的理解。TorsinA是在内质网和核膜的内腔中发现的ATP酶AAA+家族的成员。它是无处不在的表达，和已知的失败？E-突变酶拯救torsinA基因敲除动物围产期死亡表明，这种突变缺乏任何基本活动torsinA通常提供。然而，归属于torsinA的特定功能变化很大，并且没有很好地定义，尽管事实上，自从该蛋白质首次被描述并与肌张力障碍相关以来已经超过十年。这种缺乏洞察力的情况正在努力开发针对肌张力障碍的有效治疗方法。我们提出了一套实验，旨在澄清细胞功能和疾病相关的功能障碍torsinA在培养的人类细胞。我们将建立在初步的数据表明，分布torsinA内膜系统内的调节，并可能发挥重要作用，在定义酶的活性。该项目的具体目标是（1）确定torsinA与内质网膜的关联及其在该细胞器中的分布和保留的基础，（2）描述相互作用蛋白LULL 1（TOR 1 IP 2）控制torsinA在内质网和核膜之间分布的机制，（3）使用细胞和生物化学测定探索torsinA对已知底物的影响，以及（4）确定疾病相关突变如何影响torsinA的结构和功能。这些研究具有广泛的相关性，因为它们解决了调节细胞内蛋白质定位的潜在新方法，同时还提供了对DYT 1肌张力障碍病因学的深入了解。

DESCRIPTION (provided by applicant): Early-onset (DYT1) torsion dystonia is a devastating non-degenerative neurological movement disorder caused by autosomal dominant inheritance of a glutamic acid deletion in the protein torsinA (TOR1A), frequently referred to as the ?GAG or ?E mutation because of the deleted codon or amino acid. The CNS abnormalities underlying dystonia are poorly understood, with functional imaging and clinical electrophysiology studies suggesting abnormalities in a range of structures throughout the motor circuit. More specific insight should come from understanding the responsible genetic change. TorsinA is a member of the AAA+ family of ATPases found in the lumen of the endoplasmic reticulum and nuclear envelope. It is expressed ubiquitously, and the known failure of ?E-mutant enzyme to rescue torsinA knock-out animals from perinatal lethality suggests that this mutant lacks whatever essential activity torsinA normally provides. However, the specific functions ascribed to torsinA vary widely and are not well defined despite the fact that it has been more than a decade since the protein was first described and linked to dystonia. This lack of insight is creating a major roadblock in efforts to develop targeted and effective treatments for dystonia. We propose a set of experiments aimed at clarifying the cellular function and disease-linked dysfunction of torsinA in cultured human cells. We will build on preliminary data showing that the distribution of torsinA within the endomembrane system is regulated and likely to play an important role in defining the enzyme's activity. The specific aims of the project are (1) to define the basis for association of torsinA with the endoplasmic reticulum membrane and its distribution and retention in this organelle, (2) to delineate the mechanism by which an interacting protein LULL1 (TOR1IP2) controls the distribution of torsinA between the endoplasmic reticulum and nuclear envelope, (3) to explore the effects of torsinA on known substrates using cellular and biochemical assays, and (4) to determine how disease-associated mutations affect torsinA structure and function. These studies are broadly relevant because they address potentially novel means of regulating the localization of proteins within cells, while also providing insight into the etiology of DYT1 dystonia.