Phenotyping Corticospinal Axon Degeneration in Preclinical ALS Models.

目前超过30,000美国人患有肌萎缩侧索硬化症(ALS)，其特征是 由于控制大脑和脊髓的神经细胞退化而导致进行性瘫痪 有动静。几乎所有的肌萎缩侧索硬化症病例最终都是致命的，这种疾病的快速发展使其 尤其具有破坏性，大多数死亡发生在确诊后2-5年内。对于肌萎缩侧索硬化和 只有可用的治疗方法才能使疾病进展仅延缓几个月。因此，迫切需要 更有效和更具体的治疗方法，可以阻止甚至逆转神经退化。这类产品的创新 治疗只会产生于更好地理解潜在的分子和细胞机制。 病理过程。大脑皮层“上”运动神经元的变性 脊髓是肌萎缩侧索硬化症的重要标志，诊断需要皮质指征。问题的严重性 皮质病理学也与疾病进展和预后相关。因为UMN很难 区别于其他皮质细胞类型，它们在临床前研究中常常被忽视。因此，属性 这使得它们容易受到致病突变和导致它们退化的机制的影响 一直是个谜。 拟议的研究旨在通过利用尖端的分子、细胞和解剖学来克服这一点 在疾病进展过程中询问UMNS神经退化机制的技术。具体地说，这 该项目将专注于脊髓UMNS轴突的局部病理。这些纤维的丧失是一种早期的 ALS现象，以皮质脊髓束(CST)变薄和疤痕为特征，可能是 疾病发病的触发因素。在早期也观察到CST轴突的异常。 在临床前动物模型中，通常在UMN丢失之前。这笔赠款将利用ALS的一种常见小鼠模型 它利用SOD1基因(SOD1G93A)中与疾病相关的突变，并重述神经退化 在人类病人身上见过。在目标1中，将使用先进的病毒跟踪技术来标记 接受来自UMNS的直接突触输入并映射疾病期间连接性变化的小鼠脊髓 进步。同时，目标2将使用翻译核糖体亲和纯化(TRAP)方法 监测轴突中局部表达的基因的变化。目标3将检查生物能量 通过采用一种新的方法分离轴突线粒体来研究轴突的特性 疾病进展过程中的生化和代谢分析。这项探索性研究将是第一个直接 因此，解剖学、基因表达和生物能量学的变化，特别是在退化的轴突中，是相互关联的。 为进一步研究CST的病理机制奠定了基础。

Over 30,000 Americans currently suffer from amyotrophic lateral sclerosis (ALS) which is characterized by progressive paralysis due to the degeneration of nerve cells in the brain and spinal cord that control movement. Almost all cases of ALS are eventually fatal, and the rapid progression of the disease makes it particularly devastating, with most deaths occurring 2-5 years from diagnosis. No cure exists for ALS and the only available treatments slow disease progression by merely a few months Therefore, a great need exists for more effective and specific therapies that can stop or even reverse neurodegeneration. Innovation for such therapies will only arise from a better understanding of the molecular and cellular mechanisms underlying the pathological process. Degeneration of the “upper” motor neurons (UMNs) in the cerebral cortex that project to the spinal cord is an important hallmark of ALS and a cortical indication is required for diagnosis. The severity of cortical pathology also correlates with disease progression and prognosis. Because UMNs are difficult to distinguish from other cortical cell types they are often overlooked in preclinical studies. Therefore, properties that make them vulnerable to disease-causing mutations and the mechanisms that underlie their degeneration have remained a mystery. The proposed study aims to overcome this by utilizing cutting edge molecular, cellular, and anatomical techniques to interrogate neurodegenerative mechanisms in UMNs during disease progression. Specifically, this project will focus on the local pathology of the axons of UMNs in the spinal cord. Loss of these fibers is an early phenomenon of ALS and is characterized by a thinning and scarring of the corticospinal tract (CST) and may be a triggering factor for disease onset. Abnormalities in CST axons have also been observed at early time points in preclinical animal models, often preceding UMN loss. This grant will utilize a common mouse model of ALS that utilizes disease-linked mutations in the SOD1 gene (SOD1G93A) and recapitulates the neurodegeneration seen in human patients. In Aim 1, advanced viral tracing techniques will be used to label the neurons in the mouse spinal cord that receive direct synaptic input from UMNs and map changes in connectivity during disease progression. In parallel, the translating ribosome affinity purification (TRAP) method will be used in Aim 2 to monitor changes in the genes that are locally expressed in the axons. Aim 3 will examine the bioenergetic properties of the axons by employing a novel approach to isolate axonal mitochondria in order to perform biochemical and metabolic analyses during disease progression. This exploratory study will be the first to directly correlate changes in anatomy, gene expression, and bioenergetics specifically in degenerating axons, therefore laying a foundation for future work investigating mechanisms of CST pathology.