Non-Invasive Markers of Neurodegeneration in Movement Disorders

摘要 肌张力障碍是一种神经运动障碍，其特征是持续或间歇性肌肉收缩， 从而导致异常的动作和姿势。 DYT1 肌张力障碍是一种常染色体显性原发性肌张力障碍。 受影响的人都是残疾人，并且很多时候只能坐在轮椅上。 DYT1 肌张力障碍主要由 DYT1/TOR1A 外显子 5 中的框内 GAG 缺失，导致 C 端区域谷氨酸丢失 torsinA (torsinAΔE)。尽管原发性肌张力障碍通常被认为是基底神经节起源的疾病，但它是 越来越清楚的是，涉及基底神经节和小脑的大脑回路对于 导致肌张力障碍的症状。同时，我们对torsinA如何在其中发挥作用知之甚少。 特定的细胞类型和特定的大脑区域将释放运动缺陷和病理生理特征 肌张力障碍。为了解决这个问题，我们将利用我们实验团队的三项关键创新： 使我们的团队能够实现这一目标。首先，我们开发了一种分子遗传学方法，可以 选择性地针对特定细胞类型的功能，使得一些细胞仍然缺乏torsinA，而另一些细胞 功能正常。我们将使用这种方法来专门针对细胞类型，包括：1）中等多刺神经元， 基底神经节内的胆碱能神经元、多巴胺受体 2 神经元和多巴胺能神经元，2) 皮质内的谷氨酰胺能神经元，以及 3) 小脑内的浦肯野神经元。其次，我们将利用我们的 行为表型和肌电图的经验来表征肌张力障碍相关的缺陷 鼠标模型。我们将使用肌电图、后肢紧握和其他方法来量化肌肉协同收缩 肌张力障碍相关运动缺陷的测试。第三，一项关键创新将是使用先进的高场脑成像 在 11.1 特斯拉时使用体内多壳扩散成像来评估结构退化、静息态功能 磁共振成像（fMRI）评估功能连接性，感觉诱发功能磁共振成像（fMRI）评估功能连接 整个大脑感觉神经元的完整性。在目标 1 中，我们将探索对 Tor1a (Dyt1) ΔGAG 的细胞特异性影响 杂合基因敲入 (KI) 小鼠。在目标 2 中，我们将探索小鼠模型中的细胞特异性效应 通过Cre重组酶表达和torsinA的条件敲除（cKO）。行为表型的使用 非侵入性神经影像标记物将提供对细胞特异性机制的基本了解 与肌张力障碍相关，为未来的小鼠临床前治疗研究提供转化读数，以及 这里使用的神经影像标记将直接翻译给人类。

SUMMARY Dystonia is a neurological movement disorder characterized by sustained or intermittent muscle contractions, which result in abnormal movements and postures. DYT1 dystonia is an autosomal dominant primary dystonia. Affected individuals are disabled and many times confined to a wheelchair. DYT1 dystonia results primarily from an in-frame GAG deletion in exon 5 of DYT1/TOR1A, resulting in a loss of glutamic acid at the C-terminal region of torsinA (torsinAΔE). Although primary dystonia is classically considered a disorder of basal ganglia origin, it is becoming clear that brain circuits that involve both the basal ganglia and cerebellum are fundamental in contributing to the symptoms of dystonia. At the same time, we know very little about how torsinA function in specific cell types and across specific brain regions will unleash motor deficits and pathophysiological signatures of dystonia. To address this question, we will leverage three key innovations from our experimental team that position our group to accomplish this goal. First, we have developed a molecular genetics approach that can selectively target the function of specific cell types, such that some cells remain deficient in torsinA while others function normally. We will use this approach to specifically target cell types including: 1) medium spiny neurons, cholinergic neurons, dopamine receptor 2 neurons, and dopaminergic neurons within basal ganglia, 2) glutaminergic neurons within cortex, and 3) Purkinje neurons within cerebellum. Second, we will leverage our experience in behavioral phenotyping and electromyography to characterize dystonia-related deficits in the mouse models. We will quantify muscle co-contraction using electromyography, hindlimb clasping, and other tests of dystonia-related motor deficits. Third, a key innovation will be to use advanced, high-field brain imaging at 11.1 Tesla using in vivo multi-shell diffusion imaging to assess structural degeneration, resting state functional magnetic resonance imaging (fMRI) to assess functional connectivity, and sensory-evoked fMRI to assess the integrity of sensory neurons across the brain. In Aim 1, we will explore cell-specific effects on Tor1a (Dyt1) ΔGAG heterozygous knock-in (KI) mice. In Aim 2 we will explore cell-specific effects in a mouse model characterized by Cre-recombinase expression and conditional knock-out (cKO) of torsinA. The use of behavioral phenotypes and non-invasive neuroimaging markers will provide fundamental understanding of the cell-specific mechanisms related to dystonia, provide translational read-outs for future preclinical therapeutic studies in mouse, and the neuroimaging markers used here will have direct translation to humans.