Molecular Pathogenesis Studies of Rett Syndrome

描述(由申请人提供)：Rett综合征[RTT，MiM 312750]是一种X连锁的出生后发育障碍，特征是后天获得的技能丧失、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(MeCP2)的X连锁MECP2基因突变引起的。MeCP2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MeCP2与RNA结合蛋白相互作用，并可以影响RNA剪接。我们和其他人已经证明，MECP2的突变会导致一系列表现RTT部分特征的疾病，如自闭症、轻度精神发育迟滞、运动异常或癫痫。在这些患者中的一些患者和建立RTT模型的部分有症状的雌性小鼠中，有利的X染色体失活模式使我们提出，经典RTT的不同表型是由于特定神经元亚群中的MeCP2功能障碍造成的。此外，我们认为MeCP2在特定神经元中的功能丧失会导致介导神经元特异性表型的基因表达和RNA剪接变化。最后，我们认为，针对与不同表型相关的某些神经元特异性变化的药物疗法可能会调节其中一些RTT表型。该项目的具体目标是：(1)通过删除不同神经元群体中的MeCP2--使用Cre/loxP技术--确定RTT几个关键特征的神经解剖学基础，并表征条件突变小鼠的表型。(2)在复制RTT表型的Mecp 308/y小鼠中，通过评估神经元特异性基因表达和剪接模式的变化来识别MeCP2靶点；我们将使用一种新的方法，使用神经元特异性BACarray系和新的剪接/表达阵列。(3)进行针对临床相关分子变化的临床前药理学试验(基于AIMS 1和2的数据)，以确定这种疗法是否会改变RTT的病程。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MeCP2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，这些神经亚型和神经递质系统介导了RTT的某些关键特征以及相关的障碍，如自闭症和X-连锁智力低下。他们还将为社区提供丰富的神经元特异性基因表达/剪接模式资源，以及其中一些模式在RTT中的不同之处。最后但并非最不重要的一点是，这项研究产生的数据有可能确定有效的药物干预措施，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.