Molecular Pathogenesis Studies of Rett Syndrome

描述（由申请方提供）：Rett综合征[RTT，MIM 312750]是一种X连锁的出生后发育障碍，其特征为获得性技能丧失、认知和运动功能受损、自主神经功能障碍、共济失调、震颤、癫痫发作、自闭症特征和刻板的手部运动。RTT是由编码甲基CpG结合蛋白2（MeCP 2）的X连锁MECP 2基因突变引起的。MeCP 2被认为是一种转录抑制因子，将DNA甲基化与染色质修饰联系起来。最近，我们还发现MeCP 2与RNA结合蛋白相互作用，可以影响RNA剪接。我们和其他人已经表明，MECP 2突变会导致广泛的疾病，这些疾病显示出RTT的部分特征，如自闭症，轻度精神发育迟滞，运动异常或癫痫发作。有利的X染色体失活模式，在这些患者中的一些和部分症状的雌性小鼠模型RTT导致我们提出，经典RTT的不同表型的结果从MeCP 2功能障碍在一个特定的子集的神经元。此外，我们提出，MeCP 2在特定神经元中的功能丧失会导致基因表达和RNA剪接的变化，从而介导神经元特异性表型。最后，我们提出，针对与不同表型相关的一些神经元特异性变化的药物治疗可能会调节其中一些RTT表型。本项目的具体目标是：（1）通过使用Cre/LoxP技术删除不同神经元群体中的Mecp 2，并表征条件突变小鼠的表型，来确定RTT的几个关键特征的神经解剖学基础。(2)为了通过评价再现RTT表型的Mecp 308/y小鼠中的神经元特异性基因表达和剪接模式变化来鉴定MeCP 2靶标;我们将使用一种采用神经元特异性BAC阵列线和新的剪接/表达阵列的新方法。(3)针对临床相关分子变化（基于目标1和2的数据）进行临床前药理学试验，以确定此类治疗是否会改变RTT病程。作为概念证明，我们将使用调节CRH和AVP活性的药物，因为我们发现了这两个MeCP 2靶标在RTT表型中的潜在作用。这些研究将提供有关神经元亚型和神经递质系统的见解，这些神经元亚型和神经递质系统介导RTT和相关疾病（如自闭症和X连锁精神发育迟滞）的某些关键特征。他们还将为社区提供神经元特异性基因表达/剪接模式的丰富资源，以及其中一些模式在RTT中的差异。最后但并非最不重要的是，本研究产生的数据有可能确定有效的药理学干预措施，可以使RTT患者受益。

DESCRIPTION (provided by applicant): Rett syndrome [RTT, MIM 312750] is an X-linked postnatal developmental disorder characterized by loss of acquired skills, impairment of cognitive and motor functions, autonomic dysfunction, ataxia, tremors, seizures, autistic features, and stereotypic hand movements. RTT is caused by mutations in the X-linked MECP2 gene which encodes methyl-CpG-binding protein 2 (MeCP2). MeCP2 is thought to be a transcriptional repressor that links DNA methylation to chromatin modifications. Recently, we also found that MeCP2 interacts with an RNA-binding protein and can affect RNA splicing. We and others have shown that mutations in MECP2 cause a broad spectrum of disorders that display partial features of RTT such as autism, mild mental retardation, movement abnormalities, or seizures. Favorable X-chromosome-inactivation patterns in some of these patients and in partially symptomatic female mice that model RTT led us to propose that the diverse phenotypes of classic RTT result from MeCP2 dysfunction in a particular subset of neurons. Furthermore, we propose that loss of function of MeCP2 in specific neurons causes gene expression and RNA splicing changes that mediate the neuron-specific phenotypes. Lastly, we propose that pharmacologic therapies that target some of the neuron-specific changes linked to distinct phenotypes are likely to modulate some of these RTT phenotypes. The Specific Aims of this project are: (1) To identify the neuroanatomical bases of several key features of RTT by deleting Mecp2 in distinct neuronal populations -- using Cre/LoxP technology-- and characterizing the phenotypes of the conditional mutant mice. (2) To identify MeCP2 targets by evaluating neuron-specific gene expression and splicing pattern changes in Mecp 308/y mice which reproduce RTT phenotypes; we will use a novel approach that employs neuron- specific BACarray lines and new splicing/expression arrays. (3) To conduct preclinical pharmacologic trials targeted at clinically relevant molecular changes (based on Data from Aims 1 and 2) to determine if such therapies will alter the RTT disease course. As a proof of concept, we will use drugs that modulate CRH and AVP activities given our discovery of the potential roles of these two MeCP2 targets in RTT phenotypes. These studies will provide insight about the neuronal subtypes and neurotransmitter systems that mediate certain key features of RTT and related disorders such as autism and X-linked mental retardation. They will also provide the community with a rich resource of neuron-specific gene expression/splicing patterns and how some of these patterns differ in RTT. Last but not least, the data generated under this study have the potential to identify effective pharmacologic interventions that could benefit RTT patients.