An in vivo approach to understanding mutant PFN1 toxicity on motor neurons

项目总结 ALS也被称为Lou Gehrig病，是一种无法治愈的神经退行性疾病，由 运动神经元的丧失会导致瘫痪并最终死亡。为了了解这种疾病 表型人类疾病的机制和开发治疗学、哺乳动物模型 缺一不可。二十多年来，表达突变的sod1基因的转基因动物 唯一可以用来忠实地代表人类疾病并发挥重要作用的模型 促进我们对肌萎缩侧索硬化症的理解，并使治疗发展成为可能。然而，由于 缺乏其他ALS致病基因的动物模型，一直难以验证和推广 突变型SOD1模型的机制和治疗结果。因此，我们不会 了解SOD1模型中的机制发现是否适用于不同的突变体 基因，或者它是SOD1突变的专一性基因。这阻碍了我们对ALS和 治疗方面的发展。因此，模拟ALS的额外哺乳动物模型的构建 人类的疾病过程在我们对抗ALS的斗争中至关重要。然而，开发新的 进行性ALS表型导致运动神经元丢失的哺乳动物模型，临床 事实证明，瘫痪和死亡都很困难。为了解决这个问题，我们构建了一个转基因 通过表达新近发现的ALS基因突变型profilin1基因(PFN1C71G)建立小鼠模型。我们 表明表达突变体，而不是野生型(PFN1WT)基因，导致了迟发性运动 功能障碍表型，随后发展为瘫痪和死亡。此外， 突变小鼠的运动神经元不断退化，并失去了大多数 它们的运动神经元在终末阶段。这些结果表明，突变的pfn1会导致ALS。 通过获得毒性并建立进展性ALS疾病模型，该模型与 人类疾病。这些小鼠提供了一种新的体内系统，用于研究疾病机制和 治疗肌萎缩侧索硬化症这项提议利用了这一新模式，力求机械化。 对运动神经元退化的见解。目标1将区分突变的两种机制 PFN1毒性，突变蛋白获得新的毒性特性，而不是显性负抑制 正常的PFN1等位基因。Aim 2将探索这种疾病的潜在细胞决定因素 疾病的发病和进展速度。目标3将研究内质网损伤在突变中的作用 PFN1诱导运动神经元变性。我们将把这些目标的结果与 来自突变SOD1模型的发现，以确定共同的或基因特异性的机制。通过这些 了解后，可能会取得更好的治疗方法。

PROJECT SUMMARY ALS, also known as Lou Gehrig’s disease, is an incurable neurodegenerative disease caused by the loss of motor neurons leading to paralysis and eventually death. To understand the disease mechanism and develop therapeutics, mammalian models that phenocopy human disease are indispensable. For more than two decades, transgenic animals expressing mutant SOD1 gene were the only model available that faithfully represented the human disease and played an essential role in advancing our understandings of ALS and enabling therapeutic development. However, due to the lack of animal models from other ALS-causal genes, it has been difficult to verify and generalize the mechanistic and therapeutic findings from the mutant SOD1 models. Consequently, we do not know whether the mechanistic findings from the SOD1 models are common to different mutant genes or it is specific for SOD1 mutations alone. This has hampered our understanding of ALS and therapeutic development. Thus, construction of additional mammalian models that mimic ALS disease process in human is crucial in our fight against ALS. However, efforts in developing new mammalian models with progressive ALS phenotypes leading to motor neuron loss, clinical paralysis and death has proven difficult. To solve this problem, we have constructed a transgenic mouse model by expressing mutant profilin1 gene (PFN1C71G), a recently discovered ALS gene. We show that expression of the mutant, but not the wild type (PFN1WT) gene, caused a late onset motor dysfunction phenotype that subsequently progressed to paralysis and death. Furthermore, the mutant mice developed a relentless progression of motor neuron degeneration and lose a majority of their motor neurons at the end stage. These results demonstrate that mutant PFN1 causes ALS by a gain of toxicity and establish a progressive ALS disease model that closely phenocopy the human disease. These mice provide a new in vivo system for study of disease mechanisms and therapeutics for ALS. This proposal take advantage of this new model and seeks mechanistic insights on motor neuron degeneration. Aim 1 will differentiate between two mechanisms of mutant PFN1 toxicity, a gain of novel toxic property by the mutant protein vs. a dominant-negative inhibition of the normal PFN1 allele. Aim 2 will explore the underlying cellular determinants for the disease onset and the rate of disease progression. Aim 3 will investigate the role of ER damage in mutant PFN1-induced motor neuron degeneration. We will compare the findings from these aims with the findings from mutant SOD1 models to determine common or gene-specific mechanisms. By these understanding, better therapeutic approaches may be achieved.