Novel candidate mechanisms of fragile X syndrome

项目摘要 脆性X染色体综合征（FXS）是最常见的遗传性智力低下， 破坏FMR 1基因的病毒很大一部分FXS患者具有自闭症谱系障碍的特征 （ASD）。由FMR 1编码的蛋白质，脆性X智力低下蛋白（FMRP），结合mRNA， 规范他们的翻译。FMRP靶基因在人类神经发育中的功能 以及它们对FXS的贡献还不太清楚。在我的初步数据中，部分数据构成了 基于我目前正在印刷的手稿（Kwan等人，Cell，2012），我表明一氧化氮合酶1 在发育中的人类新皮层中，（NOS 1）mRNA与FMRP结合并受其调节， FXS胎儿病例中丢失。因此，NOS 1功能丧失代表了一个有前途的新候选者 FXS机制在这个应用程序中，我建议进一步追求这一令人兴奋的研究路线。在目标1中， 将研究NOS 1的缺失如何影响FXS和ASD的病理生理学，FXS是 经常合并症具体来说，我将分析：锥体NOS 1的神经生物学作用， NOS 1的遗传贡献，以及在NOS 1合成中作用于NOS 1上游的基因， 一氧化氮（NO），ASD;和锥体神经元中NOS 1信号传导的下游事件。对于目标2， 我建议使用死后人脑组织来确定FXS的其他新的候选机制 并使用FXS大脑和神经干细胞测试它们在FXS中的失调。这一多方面的建议是 预计将提供几个领域的培训，包括人类遗传学，生物化学， 人类组织处理、突触分析、神经干细胞培养和高通量测序。这 额外的培训对我成功过渡到独立至关重要。我的训练进度 在指导阶段，我寻找一个独立的职位将由我的共同导师监督 以及一个由四名具有不同专业知识的教师组成的委员会。拟议的研究有 目前的方法来研究FXS的影响，并有可能发现新的分子 不仅是FXS，还有ASD。

Project Summary Fragile X syndrome (FXS), the most common inherited form of mental retardation, result from mutations that disrupt the FMR1 gene. A large proportion of FXS patients have features of autism spectrum disorder (ASD). The protein encoded by FMR1, fragile X mental retardation protein (FMRP), binds mRNAs and regulates their translation. The identity and function of FMRP target mRNAs in human neurodevelopment and how they contribute to FXS are not well understood. In my preliminary data, parts of which formed the basis of my manuscript currently in press (Kwan et al., Cell, 2012), I show that nitric oxide synthase 1 (NOS1) mRNA is bound to and regulated by FMRP in the developing human neocortex and NOS1 protein is lost in fetal cases of FXS. Therefore, NOS1 loss of function represents a promising novel candidate mechanism of FXS. In this application, I propose to further pursue this exciting line of research. In Aim 1, I will examine how loss of NOS1 may contribute to the pathophysiology of FXS and ASD, with which FXS is often comorbid. Specifically, I will analyze: the neurobiological role of pyramidal NOS1 during development; the genetic contribution of NOS1, and genes that act upstream of NOS1 in the synthesis of nitric oxide (NO), to ASD; and the events downstream of NOS1 signaling in pyramidal neurons. For Aim 2, I propose to identify additional novel candidate mechanisms of FXS using postmortem human brain tissue and to test their dysregulation in FXS using FXS brains and neural stem cells. This multifaceted proposal is expected to provide training in several areas, including novel techniques in human genetics, biochemistry, human tissue processing, synapse analysis, neural stem cell culture, and high-throughput sequencing. This additional training is critical to my successful transition to independence. The progress of my training during the mentored phase and my search for an independent position will be overseen by my co-mentors and a committee of four additional faculty members with diverse expertise. The proposed studies have implications for current approaches to study of FXS and have the potential to uncover novel molecular pathways of not only FXS but also ASD.