Modeling the progression of SOD1-linked motor neuron disease

描述（由申请人提供）：铜锌超氧化物歧化酶1（SOD 1）相关家族性肌萎缩性侧索硬化症（fALS）是一种表型极其异质性的疾病，具有多种临床症状，可起源于上或下运动神经元，疾病持续时间范围广泛，从短至1年到长达20年。疾病的持续时间很大程度上取决于症状沿着神经轴传播的速度，直到参与呼吸的运动神经元受到影响。这种疾病如何传播的问题是ALS研究中尚未回答的主要问题之一。在过去的几年里，越来越多的证据表明，疾病传播的一种机制可能涉及一种有毒的错误折叠蛋白质沿着沿着解剖学上连接的CNS通路从一个细胞到另一个细胞的朊病毒样传播。可以在细胞之间传递有毒构象的蛋白质通常也可以在实验中在个体生物体之间传播疾病。为了调查运动神经元疾病（MND）传播的难易程度，我们将表达突变型超氧化物歧化酶1（SOD 1-G93 A和G37 R）的瘫痪小鼠制备的脊髓匀浆注射到遗传脆弱的SOD 1转基因小鼠的脊髓中。从我们测试的各种模型中，有一个显示出高度脆弱性。来自瘫痪的G93 A小鼠的组织匀浆在3-11个月时在10只表达低水平的与黄色荧光蛋白融合的G85 R-SOD 1的小鼠（G85 R-YFP小鼠）中的6只中诱导MND，并产生广泛的脊柱包涵体病理学。重要的是，来自G93 A → G85 R-YFP小鼠的匀浆第二次传代回到新生G85 R-YFP小鼠中，在3月龄时在4只小鼠中诱导疾病。来自表达G37 R变体的瘫痪小鼠的匀浆是传播差的那些匀浆之一，无论注射的受体转基因动物的品系如何，这一发现提示了表现为不同的传播MND能力的品系样特性。虽然这些初步发现非常令人兴奋，但我们认识到，我们迄今为止的研究动力不足，我们无法完全评估SOD 1相关运动神经元疾病（MND）在动物之间传播的难易程度。目的1和2提出这样的努力，以更好地了解基因型/表型相互作用，在这些模型中传播MND。我们也有非常令人兴奋的证据表明，我们可能能够创造一种模型，在这种模型中，我们可以通过将瘫痪小鼠的“感染性”组织匀浆注射到脆弱的转基因模型的坐骨神经中来局部引发疾病。然而，我们的初步数据仍然有限，需要付出更大的努力。目标3提出了这样的努力。总的来说，我们的研究旨在更好地建立SOD 1-MND传播的生物学相关性，并建立模型系统，使研究疾病进展的机制成为可能。

DESCRIPTION (provided by applicant): Cu-Zn superoxide dismutase 1 (SOD1)-linked familial amyotrophic lateral sclerosis (fALS) is an extremely heterogeneous disease phenotypically with diverse clinical symptoms that can originate in upper or lower motor neurons and with a wide range of disease durations, from as short as a year to as long as 20 years. The duration of disease is largely a function of the speed with which symptoms spread along the neuraxis until motor neurons involved in respiration become affected. The question of how the disease seems to spread is one of the major unanswered questions in the study of ALS. Over the past few years, there has been increasing evidence that one mechanism by which the disease spreads may involve a prion-like propagation of a toxic misfolded protein from cell to cell along anatomically connected pathways of the CNS. Proteins that can transmit toxic conformations between cells often can also experimentally transmit disease between individual organisms. To survey the ease with which motor neuron disease (MND) can be transmitted, we injected spinal cord homogenates prepared from paralyzed mice expressing mutant superoxide dismutase 1 (SOD1-G93A and G37R) into the spinal cords of genetically vulnerable SOD1 transgenic mice. From the various models we tested, one emerged as showing high vulnerability. Tissue homogenates from paralyzed G93A mice induced MND in 6 of 10 mice expressing low levels of G85R-SOD1 fused to yellow fluorescent protein (G85R-YFP mice) by 3-11 months, and produced widespread spinal inclusion pathology. Importantly, second passage of homogenates from G93A→G85R-YFP mice back into newborn G85R-YFP mice, induced disease in 4 of 4 mice by 3 months of age. Homogenates from paralyzed mice expressing the G37R variant were among those that transmitted poorly, regardless of the strain of recipient transgenic animal injected, a finding suggestive of strain-like properties that manifest as differing abilities to transmit MND. Although these preliminary findings are very exciting, we recognize that our studies to date are underpowered and we cannot fully assess the ease with which SOD1-linked motor neuron disease (MND) can be transmitted between animals without a much larger effort. Aims 1 and 2 propose such an effort to better understand genotype/phenotype interactions in transmitting MND in these models. We also have very exciting evidence that we might be able to create a model in which we could initiate disease focally, by injecting the "infectious" tissue homogenates from paralyzed mice in to the sciatic nerves of vulnerable transgenic models. However, again, our preliminary data is limited and much larger effort is required. Aim 3 proposes such an effort. Collectively, our studies are designed to better establish the biological relevance of SOD1-MND transmissibility and to build model systems that would enable investigations into the mechanisms of disease progression.