Neuroaxonal Dystrophy in Purkinje Cell Death in NPC Disease

描述（由申请人提供）：neemann - pick型C （NPC）病是一种胆固醇-糖鞘脂（GSL）溶酶体储存障碍，由NPC1或NPC2蛋白缺陷引起，这两种蛋白都与胆固醇和其他化合物从溶酶体中转运有关。大多数受影响的人在出生时表现正常，在生命的前十年出现行为改变和运动和智力功能的进行性损害，并在第二个十年死于疾病。目前很少有有效的治疗方法被批准，导致脑功能障碍的致病机制也知之甚少。在人类和动物模型中，鼻咽癌的一个被充分记录的特征是浦肯野细胞（PCs）的早期死亡，这被认为是导致进行性共济失调的原因。但是为什么这些细胞如此早地死亡却从未得到解释。我们提出，PC易损性是沿这些神经元轴突形成的肿胀或球体的结果。这种现象也被称为神经轴突营养不良（NAD），在各种溶酶体疾病以及其他常见的神经退行性疾病（如阿尔茨海默氏症）中都有报道。它被认为是临床神经功能障碍的主要原因，但很少被研究。重要的是，在所有已被描述为NAD的溶酶体疾病中，它是NPC疾病，其发生的规模和频率最过度，pc轴突特别易感。鼻咽癌的轴突球体含有线粒体、致密体、管泡和内体/后体样轮廓的局部积聚，可能还有自噬体，所有这些都提示轴浆运输受损。本研究的目的是利用Npc1-/-小鼠和具有固有荧光浦肯野细胞的Npc1-/-小鼠（L7-GFP Npc1-/-小鼠）进行一系列体内和体外实验，表征轴突球体的成分，并确定球体在整个疾病过程中的动态特征。我们将测试NAD和PC死亡之间关系的假设，并测试几种药物（米卢司他、环糊精和选定的抗氧化剂）在NPC小鼠模型中显示出改变球体形成的功效。了解NAD发生的原因，它与pc中溶酶体缺陷的关系，以及如何预防或逆转其发展，是治疗NPC疾病的关键问题。此外，了解将轴突病理和轴突运输缺陷与NPC致病级联的其余部分联系起来的机制可能会为更常见的神经系统疾病（如阿尔茨海默氏症）提供见解，其中轴突病理日益得到认识。

DESCRIPTION (provided by applicant): Niemann-Pick type C (NPC) disease is a cholesterol-glycosphingolipid (GSL) lysosomal storage disorder caused by defects in the NPC1 or NPC2 proteins, both of which are implicated in the trafficking of cholesterol and other compounds out of lysosomes. Most affected individuals appear normal at birth, develop behavioral changes and progressive impairment of motor and intellectual function in the first decade of life, and succumb to the disease in their second decade. Few effective treatments are currently approved and pathogenic mechanisms leading to brain dysfunction are poorly understood. One well documented feature of NPC disease that is believed to contribute to the progressive ataxia in humans and animal models is early death of Purkinje cells (PCs). But why these cells die so early has never been explained. We have proposed that PC vulnerability is a result of the formation of swellings or spheroids along the axons of these neurons. Also known as neuroaxonal dystrophy (NAD), this phenomenon has been reported in a wide variety of lysosomal diseases as well as in other commoner neurodegenerative diseases like Alzheimer's. It has been proposed to be a major contributor to clinical neurological dysfunction, yet it is rarely studied. Importantly, of all lysosomal diseases in which NAD has been described, it is NPC disease in which the scale and frequency of its occurrence is most excessive with axons of PCs being particularly susceptible. Axonal spheroids in NPC disease contain localized accumulations of mitochondria, dense bodies, tubulovesicular and endosomal/retrosomal-like profiles and possible autophagosomes, all of which are suggestive of compromise in axoplasmic transport. The goal of the current study is to use Npc1-/- mice and Npc1-/- mice with inherently fluorescent Purkinje cells (L7-GFP Npc1-/- mice) in a series of in vivo and in vitro experiments to characterize the constituents of axonal spheroids and determine the dynamic features of spheroid development throughout the course of the disease. We will test hypotheses focused on the relationship between NAD and PC death, and test the ability of several drugs (miglustat, cyclodextrins and selected antioxidants) that have shown efficacy in the NPC mouse model to modify the formation of spheroids. Understanding why NAD occurs, what its relationship is to the lysosomal defect in PCs, and what it takes to prevent or reverse its development, are critical issues for treatment of NPC disease. Moreover, understanding mechanisms that connect axonal pathology and defective axonal transport to the rest of the NPC pathogenic cascade may provide insights into more common neurological diseases like Alzheimer's where axonal pathology is increasingly recognized.