Novel candidate mechanisms of fragile X syndrome

描述(由申请人提供)：项目摘要脆性X综合征(FXS)是最常见的遗传性智力低下形式，由破坏FMR1基因的突变引起。很大比例的FXS患者具有自闭症谱系障碍(ASD)的特征。脆性X智力低下蛋白(FMRP)是由FMR1编码的蛋白，与mRNAs结合并调节其翻译。FMRP靶向mRNAs在人类神经发育中的身份和功能及其对FXS的作用尚不清楚。在我的初步数据中，部分数据构成了我目前正在出版的手稿的基础(Kwan等人，Cell，2012)，我表明一氧化氮合酶1(NOS1)mRNA在发育中的人类新皮质中与FMRP结合并受FMRP调控，在FXS胎儿病例中NOS1蛋白丢失。因此，NOS1功能缺失代表了FXS一种新的候选机制。在这份申请中，我建议进一步追求这一令人兴奋的研究方向。在目标1中，我将研究NOS1的缺失如何在FXS和ASD的病理生理学中起作用，FXS经常与ASD并存。具体地说，我将分析：锥体NOS1在发育过程中的神经生物学作用；NOS1的遗传贡献，以及NOS1上游作用于一氧化氮(NO)合成的基因对ASD的作用；以及NOS1信号在锥体神经元中的下游事件。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脑和神经干细胞来测试它们在FXS中的失调。这一多方面的应用预计将在几个领域提供培训，包括人类遗传学、生物化学、人体组织处理、突触分析、神经干细胞培养和高通量测序方面的新技术。这种额外的训练对于我成功地过渡到独立是至关重要的。我在指导阶段的培训进展和寻找独立职位的过程将由我的联合导师和一个由另外四名具有不同专业知识的教职员工组成的委员会监督。建议的研究对目前研究FXS的方法有意义，并有可能不仅发现FXS而且还发现ASD的新的分子途径。 公共卫生相关性：项目叙述脆性X综合征是最常见的精神发育迟滞的遗传形式。我建议研究脆性X综合征的分子基础。这项工作将对脆性X综合征和自闭症谱系障碍的潜在治疗方法产生影响。

DESCRIPTION (provided by applicant): 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 application 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. PUBLIC HEALTH RELEVANCE: Project Narrative Fragile X syndrome is the most common inherited form of mental retardation. I propose to study the molecular underpinnings of fragile X syndrome. This work will have implications for potential therapies for fragile X syndrome, as well as autism spectrum disorder.