Novel ALS models: FUS conditional knockout in motor neurons and oligodendrocytes

 描述(由申请人提供)： 肌萎缩侧索硬化症(ALS)是一种由上下运动神经元变性引起的致命性疾病。目前，还没有有效的治疗方法。许多有希望的干预措施在临床试验中都失败了。需要新的治疗方法，它们的发展将取决于我们对运动神经元退化机制和周围神经胶质细胞提供的支持的了解的进展。融合在肉瘤(FUS)是最新发现的导致家族性和散发性ALS的基因之一。它是与家族性和散发性ALS相关的越来越多的RNA/DNA处理基因之一。这一发现进一步强调了RNA/DNA功能和加工缺陷在神经退化中的关键作用。一个主要悬而未决的问题是，FUS功能的丧失是否会导致神经元退化。我们和其他研究人员的研究支持核功能丧失(S)在运动神经元变性中起作用的观点，然而，体内功能丧失机制的重要性仍有待确定。另一个关键问题是，FUS缺陷导致的神经退化是否是细胞自主的。我们对果蝇的研究表明，神经毒性是基于神经胶质细胞的机制。本研究假设FUS功能丧失是导致运动神经元变性的重要机制，少突胶质细胞介导的非细胞自主FUS神经毒性在ALS中起重要作用。小鼠的结构性FUS基因敲除会导致新生儿死亡和雄性不育，因此这些小鼠不能用于研究体内FUS缺失在成人神经系统中的作用。为了填补这一知识空白，我们将制作FUS条件性基因敲除小鼠，在这些小鼠中，FUS在运动神经元或少突胶质细胞中耗尽，并表征年龄相关的运动神经元丢失和相关表型。我们已经建立了FUSfl/fl小鼠系，并准备将其与神经元和少突胶质细胞Cre表达系杂交。我们将进行运动学、病理学和分子研究，以确定FUS缺乏的运动神经元是否经历年龄依赖性的退化，以及FUS缺乏的少突胶质细胞是否导致运动神经元的丢失。未来的研究将在这两个模型中探讨疾病的分子机制。最终目标是生成模型，在该模型中可以识别、表征和使用分子靶点来测试ALS的新治疗干预措施。总的来说，这些研究将填补知识的一个重要空白，并将产生有价值的小鼠模型，这些模型将被用于研究疾病机制，并作为体内平台来测试旨在减缓运动神经元丢失进展的化合物。这些研究有很大的潜力产生结果和试剂，这些结果和试剂将推进ALS研究领域，并将有利于患有运动神经元障碍的退伍军人的健康。

 DESCRIPTION (provided by applicant): Amyotrophic Lateral Sclerosis (ALS) is an invariably fatal disorder caused by degeneration of the upper and lower motor neuron. Presently, there are no effective therapies. Many promising interventions have failed in clinical trials. New therapies are needed and their development will depend on advances in our knowledge of mechanisms of motor neuron degeneration and of the support provided by the surrounding glia. Fused in sarcoma (FUS) is one of the latest genes discovered to cause familial and sporadic ALS. It is one of a growing number of RNA/DNA processing genes associated with familial and sporadic ALS. This discovery has further highlighted the pivotal role that defects in RNA/DNA function and processing have in neurodegeneration. A major unanswered question is whether loss of FUS function contributes to neuronal degeneration. Ours and other investigators studies support the notion that loss of nuclear function(s) plays a role in motor neuron degeneration, however, the importance of loss of function mechanism in vivo remains to be determined. Another critical question is whether neurodegeneration caused by FUS defects is cell-autonomous. Our studies in Drosophila suggest a glia-based mechanism of neurotoxicity. The hypothesis to be tested in this project is that loss of FUS function is a critical mechanism to cause motor neuron degeneration and non cell-autonomous FUS neurotoxicity mediated by oligodendrocytes plays an important role in ALS. Constitutive FUS knockout in mice resulted in neonatal lethality and male sterility, hence these mice cannot be used to investigate the role of loss of FUS in vivo in the adult nervous system. To fill this gap in knowledge, we will make FUS conditional knockout mice in which FUS is depleted in either motor neurons or oligodendrocytes and characterize age-dependent motor neuron loss and associated phenotypes. We have made a FUSfl/fl mouse line and we are ready to cross it with neuronal and oligodendrocyte Cre expressing lines. We will perform motor, pathological and molecular studies to determine whether FUS deficient motor neurons undergo age-dependent degeneration and whether FUS deficient oligodendrocytes contribute to motor neuron loss. Future studies will investigate the molecular mechanisms of disease in these two models. The ultimate goal is to generate models in which molecular targets can be identified, characterized and used to test novel therapeutic interventions for ALS. Collectively, these studies will fill an important gap in knowledge and will generate valuable mouse models that will be used to investigate disease mechanisms and serve as in vivo platforms to test compounds aimed at slowing progression of motor neuron loss. These studies have a great potential to generate results and reagents that will advance the field of ALS research and will benefit the health of Veterans with motor neuron disorders.