Transgenic models of ALS caused by VAPB mutation

描述（由申请人提供）：肌萎缩性侧索硬化症（ALS）是一种进行性神经退行性疾病，可导致运动神经元变性、骨骼肌萎缩、瘫痪和死亡。我们的长期目标是了解这种疾病的发病机制并找到治疗方法。目前，唯一可靠的典型ALS模型是表达SOD1突变体的小鼠。最近，VAMP相关蛋白B （VAPB）基因突变被发现可导致运动神经元变性和ALS。由于VAPB突变导致的ALS临床症状是可变的，包括典型和非典型病例。然而，所有这些都是成人发病。基于体外实验数据，关于突变型VAPB诱发ALS的机制的主要假设是该突变导致显性负活性。然而，没有体内数据可用。此外，还不排除其他可能性，如显性功能获得和功能丧失。我们建议用转基因方法区分这三种可能性，以过表达突变体VAPB，并使用转基因RNAi使小鼠VAPB沉默。这两种方法的综合数据将明确地确定这三种机制中的哪一种是正确的。由于我们的转基因构建体被设计为可诱导Cre，这些转基因小鼠将来可以通过与在各种特定细胞（神经元、胶质细胞和小胶质细胞）中表达Cre的小鼠杂交，来研究突变型VAPB在运动神经元和非运动神经元细胞中的表达作用。此外，我们建议在培养细胞中进行补充实验，以解剖VAPB的功能和突变型VAPB的功能改变。这些实验将加深我们对运动神经元退行性变机制的认识，并建立成人发病的ALS转基因二线模型，为ALS治疗策略的临床前分析提供依据。相关性：VAPB基因突变导致肌萎缩侧索硬化症（ALS），这是一种无法治愈的致命神经退行性疾病。我们建议建立细胞培养和转基因小鼠模型来研究VAPB突变如何导致神经元变性。一旦建立，这些模型可用于治疗性化合物的临床前测试。

DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that causes motor neuron degeneration, skeletal muscle atrophy, paralysis and death. Our long term objective is to understand the disease mechanism and develop a cure. At present, the only robust model for typical ALS is mice that express mutant SOD1. Recently, a mutation in VAMP associated protein B (VAPB) gene has been identified to cause motor neuron degeneration and ALS. The clinical symptom of ALS as a result of the VAPB mutation is variable and includes both typical and atypical cases. All, however, is adult onset. Based on in vitro data, the predominant hypothesis regarding the mechanism whereby mutant VAPB induces ALS is that the mutation leads to a dominant negative activity. However, no in vivo data is available. In addition, other possibilities, such as dominant gain-of-function and loss-of-function have not been ruled out. We propose to differentiate these three possibilities using transgenic approaches to overexpress the mutant VAPB and to silence the mouse VAPB using transgenic RNAi. The combined data from these two approaches will unequivocally determine which one of these three mechanisms is true. Because our transgenic constructs are designed to be Cre-inducible, these transgenic mice can be used to investigate the roles of mutant VAPB expression in motor neuron and non-motor neuron cells in the future by crossing with mice that express Cre in various specific cells (neurons, glia and microglia). Furthermore, we propose complementary experiments in cultured cells to dissect the function of VAPB and the altered function in mutant VAPB. These experiments will enhance our understanding of mechanisms of motor neuron degeneration and establish a second line of adult onset transgenic model for ALS, which can be used for preclinical analysis of therapeutic strategies for ALS. RELEVANCE: A VAPB gene mutation causes amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease without a cure. We propose to establish cell culture and transgenic mouse models to investigate how the VAPB mutation causes neuronal degeneration. Once established, these models can be used for pre-clinical tests of therapeutic compounds.