Astrocyte-synapse interactions in a rat model of Alexander disease

项目摘要 亚历山大病(AxD)是一种由神经胶质细胞基因突变引起的致死性神经退行性疾病 纤维酸性蛋白(GFAP)，星形胶质细胞的主要中间丝，导致蛋白质聚集 以及星形胶质细胞的反应性反应。AxD分为两个亚型，I型患者病情较重 起病早，认知和运动迟缓，癫痫发作，不能茁壮成长。现有的鼠标型号有 在阐明AxD星形胶质细胞病理的途径和机制方面是不可或缺的，但临床表现很少 与人类疾病相比。我们已经开发出一种新的GFAP突变大鼠模型， 出生后第三周就急剧下降，初步数据显示显著的认知能力 以及成年动物的运动障碍和神经元的潜在损失。这种新型号提供了独一无二的 研究异常星形胶质细胞-神经元相互作用在AxD中的作用的机会，特别是在 与突触和神经元数量有关。在特定的目标1中，我们将确定星形胶质细胞何时开始对 突变型GFAP及其是否与蛋白质在分子和超微结构上的聚集一致 分析。GFAP病理对星形胶质细胞成熟和存活的影响将通过量化来评估 幼年和成年大鼠出生后发育过程中神经细胞的渗透和星形胶质细胞的数量。具体而言 目的2，我们将研究星形胶质细胞病理对出生后突触发生和神经元存活的影响。 通过量化突触的形成、成熟和消除，以及幼年和 成年动物。为了进一步确定星形胶质细胞功能障碍对AxD神经元的影响，我们将进行 急性分离的星形胶质细胞(Aim 1)和神经元(Aim 2)在不同阶段的转录图谱 疾病的发展。这些数据将被用来评估突触产生的线索和炎症反应的平衡 和保护途径，并与突触支持中正常星形胶质细胞功能的潜在丧失相关 在疾病的发展过程中。在具体目标3中，将对幼年动物进行测试，以确定是否 认知和运动障碍在严重的临床表型出现之前就很明显了。最后，我们会 使用反义技术检测神经元和认知表型在早期和晚期的挽救 通过抑制GFAP引起的疾病。这项工作将发现发病机制的新特征，改善我们的 了解神经元的继发性变化，并测试这些表型在不同时间的可逆性 疾病的各个阶段。

Project Summary Alexander disease (AxD) is a fatal neurodegenerative disease caused by mutations in the gene for glial fibrillary acidic protein (GFAP), the major intermediate filament of astrocytes, which lead to protein aggregation and a reactive astrocyte response. AxD is classified into two subtypes, with the more severe Type I patients having early onset with cognitive and motor delays, seizures, and failure to thrive. Existing mouse models have been integral in elucidating pathways and mechanisms in AxD astrocyte pathology, but display minimal clinical deficits compared to the human disease. We have developed a new GFAP mutant rat model that exhibits precipitous decline just after the third postnatal week, and preliminary data demonstrate significant cognitive and motor impairment and the potential loss of neurons in adult animals. This new model offers unique opportunities to investigate the contribution of abnormal astrocyte-neuron interaction in AxD, particularly with respect to synapses and neuron number. In Specific Aim 1, we will determine when astrocytes begin to react to mutant GFAP and whether this coincides with protein aggregation through both molecular and ultrastructural analysis. The effects of GFAP pathology on astrocyte maturation and survival will be assessed by quantifying neuropil infiltration during postnatal development, and astrocyte numbers in juvenile and adult rats. In Specific Aim 2, we will examine the effects of astrocyte pathology on postnatal synaptogenesis and neuronal survival by quantifying synapse formation, maturation, and elimination, as well as numbers of neurons in juvenile and adult animals. To further define the effects of astrocyte dysfunction on neurons in AxD, we will perform transcription profiling with acutely isolated astrocytes (Aim 1) and neurons (Aim 2) at different stages of disease development. These data will be used to assess synaptogenic cues and the balance of inflammatory and protective pathways, and to correlate the potential loss of normal astrocyte functions in synaptic support throughout disease progression. In Specific Aim 3, juvenile animals will be tested to determine whether cognitive and motor impairment are apparent before the onset of severe clinical phenotypes. Finally, we will use antisense technology to test rescue of neuronal and cognitive phenotypes at early and late stages of disease by GFAP suppression. This work will identify new features of pathogenesis, improve our understanding of the secondary changes in neurons, and test the reversibility of these phenotypes at different stages of disease.