The mechanism of Rett Syndrome rescue by astrocytes

 描述（由申请人提供）：尽管在识别神经病理学基础的缺陷基因方面取得了进展，但这些缺陷如何导致症状尚不清楚，并且这种差距是治疗的一个可怕的绊脚石。一个恰当的例子是Rett综合征（RTT），这是一种严重的女孩神经系统疾病。这种疾病是由于转录因子MeCP 2的零星突变引起的，但为什么MeCP 2的缺失会导致神经病理学是个谜。此外，RTT在神经系统疾病中占有独特的地位，因为通过在整个大脑或仅在星形胶质细胞（大脑中突出的神经胶质细胞类型）中表达MeCP 2，小鼠的关键症状是可逆的。拯救打开了治疗方法的大门，但需要更好地了解RTT的缺陷，以及MeCP 2恢复后拯救的确切内容。传统的方法，如微阵列分析，几乎只关注单个基因转录本的变化，主要是在神经元中。这种方法尚未导致关于MeCP 2的功能或疾病的细胞基础的明确答案，部分原因是细胞异质性。它也忽略了星形胶质细胞在症状中的作用。在任何情况下都没有拯救程度的分子基准。我们的目标是通过特别关注星形胶质细胞对RTT症状的拯救来解决这些问题。在这里，我们使用RNA测序结合膜蛋白质组学对脑和从小鼠脑中分选的纯细胞群体进行共表达网络分析（目的1）。着眼于人类特异性治疗，我们确定了RTT患者IPSC神经细胞中MeCP 2损失和获得的分子和细胞后果，并在人/小鼠异种移植物中测试了这些研究的预测（目的2）。最后，我们测试了一个新的假设（目标3），根据最近的初步结果，减少星形胶质细胞和神经元之间的兴奋性信号可能是这些细胞的分子和膜特性的改变的功能结果（目标1和2）。

 DESCRIPTION (provided by applicant): Despite advances in identifying defective genes underlying neuropathologies, how these defects underlie symptoms is not known, and this gap is a formidable stumbling block for therapeutics. A case in point is Rett Syndrome (RTT), a severe neurological disease in girls. The disease is due to sporadic mutations in the transcription factor, MeCP2, but why loss of MeCP2 causes neuropathology is enigmatic. Further, RTT holds a unique place in neurological disease because key symptoms are reversible in mice by expressing MeCP2 throughout the brain or just in astrocytes, the prominent glial cell type in brain. The rescue opens the door to therapeutic approaches, but requires a better understanding of what is deficient in RTT and precisely what is rescued upon MeCP2 restoration. Traditional approaches, such as microarray analysis, have focused almost exclusively on individual gene transcript changes, primarily in neurons. This approach has not led to clear answers about the functions of MeCP2 or the cellular basis of the disease, in part due to cellular heterogeneity. It also ignores work indicating a role for astrocytes in contributin to symptoms. In no case is there a molecular benchmark for extent of rescue. Our goal is to attack these issues head on by focusing specifically on rescue of RTT symptoms by astrocytes. Here, we perform a co-expression network analysis, using RNA seq combined with membrane proteomics, on brain and on pure populations of cells sorted from murine brain (aim 1). With an eye towards human-specific therapies, we identify the molecular and cellular consequences of loss and gain of MeCP2 in neural cells from RTT patient IPSCs, and test predictions from these studies in human/mouse xenografts (aim 2). Finally, we test a new hypothesis (aim 3), based on recent preliminary results, that reduced excitatory signaling between astrocytes and neurons may be a functional outcome of the alterations in molecular and membrane properties of these cells (aims 1 and 2).