Eukaryotic Initiation Factor 2a Signaling in Dystonia Pathogenesis and Treatment

摘要 肌张力障碍是一种以持续和痛苦的不自主姿势为特征的衰弱性运动障碍，是第三大最常见的运动障碍，但对其生物学原因知之甚少。目前，只有对症治疗，疗效有限，副作用明显，而且往往是侵入性的或需要进入专门设施。早发性扭转性肌张力障碍（DYT 1）是最常见的遗传性肌张力障碍，是一种严重的儿童期发病形式。最近，我们的实验室使用一种新的DYT 1细胞病理学检测方法进行了全基因组RNAi筛选，该方法确定了真核启动因子2α（eIF 2 α）信号通路是最高度富集的通路。在随后的实验中，我们的实验室表明，增强eIF 2 α信号传导的化合物改善了DYT 1细胞病理学，抑制eIF 2 α信号传导的化合物以剂量依赖性方式恶化了病理学，表明增强eIF 2 α信号传导对DYT 1具有保护作用，反之亦然。DYT 1-同基因模型小鼠在已知需要eIF 2 α信号传导的突触过程中存在缺陷，并且来自DYT 1患者的成纤维细胞在响应于应激刺激时显示出减少的eIF 2 α信号传导，这表明eIF 2 α信号传导在体内DYT 1中存在缺陷。此外，在患有其他形式的肌张力障碍的患者中发现eIF 2 α信号传导的上游激活物和下游效应物的突变，这表明缺陷的eIF 2 α信号传导在非DYT 1肌张力障碍发病机制中也是关键的。因此，我假设缺乏eIF 2 α信号传导是肌张力障碍发病机制的关键介质，并且增强eIF 2 α信号传导将在肌张力障碍的动物模型中具有治疗作用。在此我提议：1）通过a）测量野生型和DYT 1模型小鼠中的神经元eIF 2 α信号传导和B）确定DYT 1致病突变如何导致eIF 2 α信号传导缺陷，确定eIF 2 α信号传导在DYT 1中如何被破坏。2)使用切片电生理学确定增强eIF 2 α信号传导是否逆转DYT 1模型小鼠中的突触可塑性缺陷。3)确定抑制elF 2 α信号传导是否足以在野生型小鼠中引起张力障碍表型，无论是单独还是与环境应激联合。

ABSTRACT Dystonia, a debilitating movement disorder characterized by sustained and painful involuntary postures, is the 3rd most common movement disorder yet very little is known about its biological cause. Currently, only symptomatic treatments are available, which have limited efficacy, significant side effects, and are often invasive or require access to specialized facilities. Early-onset torsion dystonia (DYT1), the most common inherited form of dystonia, is a severe, childhood-onset form of the disease. Recently, our lab conducted a whole-genome RNAi screen using a novel assay of DYT1 cellular pathology, which identified Eukaryotic lnitiation Factor 2α (elF2α) signaling as the most highly enriched pathway. ln subsequent experiments, our lab showed that a compound which enhances elF2α signaling improved the DYT1 cellular pathology and a compound which inhibits elF2α signaling worsened the pathology in a dose-dependent manner, indicating that enhancing elF2α signaling is protective against DYT1 and vice versa. DYT1-isogenic model mice are deficient in a synaptic process known to require elF2α signaling and fibroblast cells derived from DYT1 patients display decreased elF2α signaling in response to stress stimulation, suggesting that elF2α signaling is deficient in DYT1 in vivo. Furthermore, mutations in both an upstream activator and a downstream effector of elF2α signaling are found in patients with other forms of dystonia, suggesting that defective elF2α signaling is critical in non-DYT1 dystonia pathogenesis as well. Therefore, l hypothesize that deficient elF2α signaling is a critical mediator of dystonia pathogenesis and that pharmacologically enhancing elF2α signaling will have therapeutic effects in animal models of dystonia. Here l propose to: 1) Determine how elF2α signaling is disrupted in DYT1 by a) measuring neuronal elF2α signaling in wild type and DYT1 model mice and b) determining how the DYT1-causative mutation leads to deficient elF2α signaling. 2) Determine if enhancing elF2α signaling reverses a synaptic plasticity deficit in DYT1 model mice using slice electrophysiology. 3) Determine if inhibiting elF2α signaling is sufficient to cause dystonic phenotypes in wild-type mice, either alone or in conjunction with environmental stress.