New Models For Astrocyte Function in Genetic Mouse Models of Autism Spectrum Diso

描述（由申请人提供）：自闭症谱系障碍（ASD）是以社交和沟通功能障碍为突出表现的精神疾病。这些复杂的行为变化是由特定大脑区域的突触功能改变引起的。以前的研究主要集中在改变神经元的发育和成熟。除了这些神经元的变化，最近的研究表明，星形胶质细胞，大脑中的主要神经胶质细胞，作为ASD发病机制的主要贡献者。星形胶质细胞是三联突触的组成部分。在该模型中，星形胶质细胞过程围绕和/或与突触前和突触后组分相关联，并调节神经递质稳态和再循环，为神经元代谢提供基本底物，螯合Ca 2+离子并促进突触发生和突触重塑。星形胶质细胞也参与了遗传性人类ASD动物模型的发病机制;这些模型包括缺乏甲基CpG结合蛋白2（MeCP2）或脆性X智力低下1（FMR 1）基因的小鼠。虽然星形胶质细胞的多样性已被公认为超过世纪，分子和细胞机制的基础上，这种多样性在体内和精神疾病的后果仍然知之甚少。本建议的目的是表征星形胶质细胞的多样性在两个小鼠模型的自闭症谱系障碍的灰质星形胶质细胞亚群。我们的实验是由两个技术进步，允许识别和分子表征的星形胶质细胞在动物模型的ASD促进。首先，我们已经产生了一种新的转基因小鼠品系（BT4-mEGFP），其中星形胶质细胞表面膜从胚胎发育开始就被荧光标记。将这些荧光标记的星形胶质细胞培育成ASD的遗传模型将允许通过荧光激活细胞分选和随后的基因分析来分离星形胶质细胞。我们将确定这些基因缺陷如何改变星形胶质细胞的发育，星形胶质细胞与突触的关联以及基因谱研究中鉴定的星形胶质细胞蛋白的表达。这些数据将通过使用自动连续电子显微镜确定星形胶质细胞和突触之间的三维关联来扩展。我们的研究是基于总体假设，即星形胶质细胞在ASD中起两个关键作用。首先，它们与突触有异常关联，这导致神经递质稳态改变和神经元电活动异常。其次，它们改变了线粒体功能，缺乏ATP生产和Ca2+缓冲，这降低了它们为神经元提供基本营养的能力。这些研究将阐明星形胶质细胞在ASD中先前未识别的作用，并将为未来治疗策略的发展提供关键的遗传和超微结构框架，这些治疗策略靶向星形胶质细胞在治疗或预防ASD中的功能。

DESCRIPTION (provided by applicant): Autism spectrum disorders (ASDs) are psychiatric disorders highlighted by social and communicative dysfunction. These complex behavioral changes are caused by altered synaptic functioning in select brain regions. Studies have previously focused on altered neuronal development and maturation. In addition to these neuronal changes, more recent studies have implicated astrocytes, the major glial cell in the brain, as major contributors to the pathogenesis of ASDs. Astrocytes are integral components of the tripartite synapse. In this model astrocyte processes surround and/or associate with pre- and post-synaptic components and regulate neurotransmitter homeostasis and recycling, provide basic substrates for neuronal metabolism, sequester Ca2+ ions and promote synaptogenesis and synaptic remodeling. Astrocytes have also been implicated in the pathogenesis of animal models of inherited human ASDs; these include mice lacking methyl-CpG-binding protein 2 (MeCP2) or the fragile X mental retardation 1 (FMR1) gene. While astrocyte diversity has been recognized for over a century, the molecular and cellular mechanisms underpinning this diversity in vivo and the consequences for psychiatric disorders remain poorly understood. The purpose of this proposal is to characterize astrocyte diversity in subpopulations of gray matter astrocytes in two mouse models of ASDs. Our experiments are facilitated by two technical advances that permit the identification and molecular characterization of astrocytes in animal models of ASDs. First, we have produced a novel transgenic mouse line (BT4-mEGFP) in which astrocyte surface membranes are fluorescently tagged from embryonic development onward. Breeding of these fluorescently tagged astrocytes into genetic models of ASDs will permit astrocyte isolation by fluorescent activated cell sorting and subsequent gene profiling. We will establish how these gene defects alter the development of astrocytes, the association of astrocytes with synapses and the expression of astrocyte proteins identified in the gene profiling studies. These data will be extended by determining the three dimensional associations between astrocytes and synapses using automated serial electron microscopy. Our studies are based upon the overall hypotheses that astrocytes play two key roles in ASDs. First, they have abnormal associations with synapses, which results in altered neurotransmitter homeostasis and abnormal neuronal electrical activity. Second they have altered mitochondrial functions, deficient ATP production and Ca2+ buffering, which reduces their ability to provide basic nutrition to neurons. These studies will elucidate previousl unidentified roles of astrocytes in ASDs and will provide a critical genetic and ultrastructural framework for the development of future therapeutic strategies that target astrocyte function in treating or preventing ASDs.