Cellular and molecular determinants of DDX3X syndrome

项目摘要 我们对DDX 3X综合征的理解存在根本性的差距，DDX 3X综合征是一种遗传疾病， 女性智力残疾（ID）的2%，由X连锁基因DDX 3X突变引起。最 受影响的个体是具有DDX 3X单倍不足的女性。最近的一项研究使用细胞模型和子宫内 在小鼠中的操作表明，Ddx 3x调节皮质神经发生和mRNA翻译， 神经元祖细胞然而，缺乏具有DDX 3X综合征结构效度的小鼠模型阻碍了 忠实地捕捉所观察到的认知、社会和运动缺陷的分子和细胞决定因素， DDX 3X综合征患者中。迫切需要填补这些空白，因为在我们这样做之前， 了解DDX 3X综合征和开发有效的治疗方法仍然遥不可及。为了解决这个 为了满足未满足的需求，在我们的实验室中产生了小鼠模型DDX 3X单倍不足（Ddx 3x +/-）。的 长期目标是揭示ID的病理生理学并确定治疗靶点。整体 目的是捕获DDX 3X综合征的分子和细胞机制。中央 假设是Ddx 3x决定了皮层投射神经元的形成，这些神经元有助于认知、社交和 运动功能，并通过调节发育中的皮质中的mRNA翻译来实现。理由是， 一旦我们在小鼠模型中鉴定了DDX 3X综合征的机制和可靠的表型， 可以开发和测试治疗方法。该假设将通过追求三个具体目标进行测试：1） 评估DDX 3X综合征小鼠模型中的神经发育缺陷; 2）捕获DDX 3X综合征小鼠模型中的分子缺陷。 DDX 3X综合征小鼠模型中的缺陷;以及，3）将细胞功能与DDX 3X综合征中的行为结果相关联。 ddx 3x突变小鼠。在目标1下，发展和成人认知，社会和运动行为， 将使用标准化行为电池测量Ddx 3x +/-小鼠。皮质投射神经元将 在Ddx 3x +/-小鼠中通过结合细胞和体内（例如，子宫内电穿孔）方法。下 目的2：利用翻译核糖体亲和纯化技术定位投射神经元中的Ddx 3x靶点 （TRAP）方法用于发现和其基于病毒的开发（vTRAP）用于独立验证。目标之下 3、在前脑或特定皮质层中具有基因消融的条件性Ddx 3x小鼠将被测试用于 发展和成人行为。这项提议是创新的，因为它解决了神经生物学的主要问题。 未知ID基因，并表征DDX 3X综合征的第一个小鼠模型。它也是创新的，因为它 桥梁遗传学，生物化学，分子和细胞神经科学，发育生物学，和行为 神经科学该应用是重要的，因为它将促进我们对ID病理生理学的理解， 同时为大脑功能的基本过程皮质生成提供了新的线索。这些结果 预计将产生积极的影响，因为它们将为ID的新型治疗干预铺平道路。

PROJECT SUMMARY There are fundamental gaps in our understanding of DDX3X syndrome, a genetic condition accounting for up to 2% of intellectual disability (ID) in females and caused by mutations in the X-linked gene DDX3X. Most affected individuals are females with DDX3X haploinsufficiency. A recent study using cell models and in utero manipulations in mouse has shown that Ddx3x regulates cortical neurogenesis and mRNA translation in neuronal progenitors. Yet, the lack of a mouse model with construct validity for DDX3X syndrome has impeded to faithfully capture the molecular and cellular determinants of the cognitive, social and motor deficits observed in individuals with DDX3X syndrome. There is a critical need to fill these gaps because, until we do so, understanding DDX3X syndrome and developing effective therapeutics remain out of reach. To address this unmet need, a mouse modeling DDX3X haploinsufficiency (Ddx3x+/-) was generated in our laboratory. The long-term goal is to unravel the pathophysiology of ID and identify targets for therapeutics. The overall objective is to capture the molecular and cellular mechanisms underlying DDX3X syndrome. The central hypothesis is that Ddx3x dictates the formation of cortical projection neurons subserving cognitive, social, and motor functions, and does so by regulating mRNA translation in the developing cortex. The rationale is that, once we identify the mechanisms of DDX3X syndrome and reliable phenotypes in the mouse model, therapeutics can be developed and tested. The hypothesis will be tested by pursuing three Specific Aims: 1) Assess the neurodevelopmental defects in a mouse model of DDX3X syndrome; 2) Capture the molecular defects in a mouse model of DDX3X syndrome; and, 3) Correlate cellular function to behavioral outcomes in Ddx3x mutant mice. Under Aim 1, the developmental and adult cognitive, social, and motor behavior of Ddx3x+/- mice will be measured with a standardized behavioral battery. Cortical projection neurons will be studied in Ddx3x+/- mice by combining cellular and in vivo (e.g., in utero electroporation) approaches. Under Aim 2, Ddx3x targets in projection neurons will be mapped using the translating ribosome affinity purification (TRAP) method for discovery and its viral-based development (vTRAP) for independent validation. Under Aim 3, conditional Ddx3x mice with the gene ablated in the forebrain or in specific cortical layers will be tested for development and adult behavior. The proposal is innovative because it addresses the neurobiology of a largely unknown ID gene and characterizes the first mouse model of DDX3X syndrome. It is also innovative because it bridges genetics, biochemistry, molecular and cellular neuroscience, developmental biology, and behavioral neuroscience. The application is significant because it will advance our understanding of ID pathophysiology, while shedding new light on corticogenesis, a fundamental process for brain functioning. These results are expected to have a positive impact because they will pave the way for novel therapeutic interventions for ID.