TorsinA mediated regulation of Cdc42 signaling and DYT1 dystonia

项目总结/摘要 DYT 1肌张力障碍是一种破坏性的神经运动障碍，其特征是肌肉不受控制 导致不正常的、不自主的姿势的收缩。DYT 1肌张力障碍是由DYT 1基因中的一个缺失（Δgag; ΔE）引起的。 Tor 1A基因编码与各种细胞活性相关的管腔ATP酶（AAA+）蛋白 扭转A.ΔE突变如何导致DYT 1肌张力障碍尚不清楚，因为基本的细胞功能 由torsinA执行的操作未知。这项建议旨在填补这些关键的知识空白， 使急需的靶向治疗的合理设计成为可能。我们最近的工作表明，torsinA是i） 所需的机械信号转导从细胞骨架到核质通过核 核骨架和细胞骨架（LINC）复合物的跨膜接头; ii）信号传导的激活 由Rho GTdR Cdc 42介导; iii）以及适当的轴突生长和生长锥形态。 重要的是，在DYT 1的脑中观察到与临床严重程度相关的轴突束破坏。 在肌张力障碍患者中，LINC复合物和Cdc 42都介导轴突的延伸和引导。因此我们 假设有缺陷扭转蛋白A依赖的机械化学信号转导有助于DYT 1 肌张力障碍发病机制我们将在培养的哺乳动物细胞和非洲爪蛙中检验这一假设 非洲爪蟾使用一系列已建立的和新的生物化学，生物物理，荧光Rho GTdR 生物传感器、定量成像和蛋白质组学以及合成生物学方法。在这一提议中， 我们将定义torsinA及其共激活因子，内核膜蛋白LAP 1，如何调节 在培养的哺乳动物细胞中组装功能性LINC复合物（Aim 1）。我们将确定如何折磨 和它的另一个辅激活因子，外核膜蛋白LULL 1，控制Cdc 42的激活， 培养的哺乳动物细胞（Aim 2）。最后，我们将测试torsinA依赖的机械化学信号的作用， 在培养的X.在胚胎的大脑中，也有类似的现象（Aim 3）。 这些目标的结果将提供宝贵的机械见解的新兴作用， 核被膜作为发育和疾病的信号节点。此外，他们将把 为未来开发治疗其他形式的新治疗策略奠定基础 肌张力障碍，肌张力障碍加上其中肌张力障碍可与另一种神经系统疾病一起发生的综合征 例如亨廷顿氏病和帕金森氏病，以及其他神经和神经精神疾病 由LINC复合物蛋白突变引起的疾病，包括自闭症、共济失调、双相情感障碍、痴呆， 和精神分裂症

PROJECT SUMMARY/ABSTRACT DYT1 dystonia is a devastating neurological movement disorder characterized by uncontrolled muscle contractions that result in abnormal, involuntary postures. DYT1 dystonia is caused by a deletion (Δgag; ΔE) in the Tor1A gene encoding the luminal ATPases associated with various cellular activities (AAA+) protein torsinA. How the ΔE mutation causes DYT1 dystonia remains unclear because the basic cellular function performed by torsinA is unknown. This proposal seeks to close these critical gaps in knowledge, which will enable the rational design of urgently needed targeted therapies. Our recent work suggests that torsinA is i) required for the transduction of mechanical signals from the cytoskeleton into the nucleoplasm via the nuclear envelope spanning linker of nucleoskeleton and cytoskeleton (LINC) complex; ii) the activation of signaling mediated by the Rho GTPase Cdc42; iii) as well as proper axon outgrowth and growth cone morphology. Importantly, axonal tract disruptions that correlate with clinical severity are observed in the brains of DYT1 dystonia patients and the both the LINC complex and Cdc42 mediate axon elongation and guidance. Thus, we hypothesize that defective torsinA-dependent mechano-chemical signal transduction contributes to DYT1 dystonia pathogenesis. We will test this hypothesis in cultured mammalian cells and the African clawed frog Xenopus laevis using an array of established and novel biochemical, biophysical, fluorescent Rho GTPase biosensors, quantitative imaging and proteomics, as well as synthetic biological approaches. In this proposal, we will define how torsinA and its co-activator, the inner nuclear membrane protein LAP1, regulate the assembly of functional LINC complexes in cultured mammalian cells (Aim 1). We will determine how torsinA and its other co-activator, the outer nuclear membrane protein LULL1, control the activation of Cdc42 in cultured mammalian cells (Aim 2). Finally, we will test the role of torsinA-dependent mechano-chemical signal transduction during axon outgrowth in cultured X. laevis neurons and in the brains of living embryos (Aim 3). The results of these Aims will provide invaluable mechanistic insights into the emerging role of the nuclear envelope as a signaling node in development and disease. Furthermore, they will lay the foundation for the future development of novel therapeutic strategies for the treatment of other forms of dystonia, dystonia plus syndromes in which dystonia can occur in conjunction with another neurological disorder such as Huntington's and Parkinson's diseases, as well as other neurologic and neuropsychiatric diseases caused by mutations in LINC complex proteins including autism, ataxia, bipolar disorder, dementia, and schizophrenia.