Eukaryotic Initiation Factor 2a Signaling in Dystonia Pathogenesis and Treatment

摘要 肌张力障碍是一种以持续而痛苦的非自愿姿势为特征的衰弱运动障碍，是第三种最常见的运动障碍，但对其生物学原因知之甚少。目前，只有对症治疗可用，这些治疗效果有限，副作用显著，而且往往是侵入性的或需要使用专门的设施。早发性扭转肌张力障碍(DYT1)是肌张力障碍最常见的遗传形式，是一种严重的儿童期发病形式。最近，我们的实验室利用一种新的DYT1细胞病理学方法进行了全基因组RNA干扰筛选，确定真核启动因子2α(elF2α)信号是最高丰度的信号通路。在随后的实验中，我们的实验室表明，增强elF2α信号的化合物改善了DYT1细胞的病理，而抑制elF2α信号的化合物以剂量依赖的方式恶化了病理，表明增强elF2α信号对DYT1具有保护作用，反之亦然。DYT1-等基因模型小鼠在需要elF2α信号的突触过程中存在缺陷，来自DYT1患者的成纤维细胞对应激刺激的反应显示elF2α信号减少，这表明在体内DYT1缺乏elF2α信号。此外，在其他形式的肌张力障碍患者中也发现了elF2α信号的上游激活因子和下游效应因子的突变，这表明elF2α信号的缺陷在非DYT1肌张力障碍的发病机制中也是至关重要的。因此，L推测，elF2α信号的缺失是肌张力障碍发病的关键介质，药物增强的elF2α信号对肌张力障碍动物模型有治疗作用。在这里，L建议：1)通过a)在野生型和DYT1模型小鼠中检测神经元elF2α信号，以及b)确定导致DYT1的突变如何导致elF2α信号缺陷，来确定elF2α信号在DYT1中是如何被破坏的。2)用切片电生理学方法确定增强elF2α信号是否能逆转DYT1模型小鼠突触可塑性缺陷。3)确定抑制elF2α信号是否足以导致野生型小鼠的肌张力障碍表型，无论是单独还是与环境应激一起。

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.