The mechanism of Rett Syndrome rescue by astrocytes

 描述(申请人提供)：尽管在识别神经病理学基础上的缺陷基因方面取得了进展，但这些缺陷是如何导致症状的尚不清楚，这一差距是治疗学的一个巨大绊脚石。雷特综合症(RTT)就是一个很好的例子，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MeCP2的零星突变造成的，但为什么MeCP2的缺失会导致神经病理是一个谜。此外，RTT在神经系统疾病中具有独特的地位，因为关键症状在小鼠身上是可逆的，通过在整个大脑中表达MeCP2或仅在星形胶质细胞中表达MeCP2，星形胶质细胞是大脑中主要的胶质细胞类型。抢救为治疗方法打开了大门，但需要更好地了解RTT的不足之处，以及MeCP2修复后到底挽救了什么。传统的方法，如微阵列分析，几乎只关注单个基因转录的变化，主要是在神经元中。这种方法没有导致关于MeCP2的功能或疾病的细胞基础的明确答案，部分原因是细胞的异质性。它还忽略了星形胶质细胞在导致症状中所起作用的研究。在任何情况下，都不存在救援程度的分子基准。我们的目标是通过专门关注星形胶质细胞抢救RTT症状来正面解决这些问题。在这里，我们使用RNA序列和膜蛋白质组学相结合的方法，在脑和从小鼠脑中分离的纯细胞群上进行共表达网络分析(目标1)。着眼于人类特有的治疗，我们确定了RTT患者iPSCs神经细胞中MeCP2丢失和获得的分子和细胞后果，并在人/鼠异种移植中测试了这些研究的预测(目标2)。最后，基于最近的初步结果，我们测试了一个新的假说(目标3)，即星形胶质细胞和神经元之间兴奋性信号的减少可能是这些细胞的分子和膜属性改变的功能结果(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).