The influence of common genetic variation on brain overgrowth pathways

项目摘要 许多患有单基因和特发性自闭症谱系障碍（ASD）的个体表现出更大的大脑 体积和过度扩张的新皮层表面积在生命早期。神经祖细胞数量的增加 池，目前几乎完全在胎儿发育，是一个很好的描述机制，可以导致 新皮层表面积扩大。许多ASD连锁突变影响参与Wnt信号传导的基因， 调节神经祖细胞增殖的途径此外，Wnt附近的常见遗传变异- 通路基因与成人皮质表面积的变化有关。常见的变异 ASD风险中的作用。大型和不断增长的全基因组关联财团正在识别常见的变异 与ASD风险相关的基因座。基于这些数据，我们假设常见和罕见的变异 通过改变Wnt信号传导影响胎儿发育中新皮质祖细胞增殖， 皮质表面积过度扩张和ASD风险增加。该项目的主要目标是确定 影响基因表达、Wnt信号传导和对Wnt应答的增殖的常见遗传变异 在来自107个遗传上不同的供体的原代人神经元祖细胞系（phNPC）中，到 为了实现这一目标，我们将首先量化对Wnt转录反应的个体间变异性 调制器。为了调节Wnt信号传导，我们将利用两种临床相关的化合物（丙戊酸、锂 氯化物）以及最有效和选择性的Wnt激活化合物（CT 99021）。接下来我们就 通过高通量荧光素酶测定定量经典Wnt信号传导和通过 流式细胞术测定，在该细胞群中响应于这些Wnt调节剂。最后，我们将执行一个 使用我们在这些细胞系上收集的表型进行遗传关联，以识别共同的变异基因座 与转录、Wnt信号传导和对Wnt调节剂的神经祖细胞增殖反应相关。 我们将确定这些相同的位点是否也通过共同作用影响ASD和皮质表面积的风险。 利用现有的全基因组关联研究的定位技术。这项研究可以让我们了解 ASD相关遗传变异的作用机制，涉及细胞类型和发育 过程，这可能会导致更彻底的了解ASD的发病机制。此外，作为产前 暴露于丙戊酸是ASD的已知环境风险因素，这项研究可能会识别遗传变异 影响对丙戊酸的反应性，可预测不良神经发育影响 根据基因型。

Project Summary Many individuals with monogenic and idiopathic forms of autism spectrum disorder (ASD) exhibit larger brain volumes and a hyper-expansion of neocortical surface area early in life. An increase in the neural progenitor pool, present almost exclusively during fetal development, is a well-described mechanism that can lead to expansion of neocortical surface area. Numerous ASD-linked mutations affect genes involved in Wnt signaling, a pathway that regulates neural progenitor proliferation. In addition, common genetic variants near Wnt- pathway genes are associated with changes in cortical surface area in adults. Common variation plays a large role in ASD risk. Large and ever-growing genome-wide association consortia are identifying common variant loci associated with ASD risk. Based on these data, we hypothesize that both common and rare variants impact neocortical progenitor proliferation in fetal development by altering Wnt signaling, leading to post-natal cortical surface area hyper-expansion and increased ASD risk. The primary goal of this project is to identify common genetic variants influencing gene expression, Wnt signaling, and proliferation in response to Wnt modulators in primary human neuronal progenitor cell lines (phNPCs) from 107 genetically diverse donors. To accomplish this goal, we will first quantify inter-individual variability in transcriptional response to Wnt modulators. To modulate Wnt signaling, we will utilize two clinically relevant compounds (Valproic Acid, Lithium Chloride) as well as the most potent and selective Wnt activating compound available (CT99021). Next, we will quantify both canonical Wnt signaling, through a high-throughput luciferase assay, and proliferation, through a flow cytometry assay, in response to these Wnt modulators in this population of cells. Finally, we will perform a genetic association using the phenotypes we have collected on these cell lines to identify common variant loci associated with transcriptional, Wnt signaling and neural progenitor proliferation responses to Wnt modulators. We will determine if these same loci also influence risk for ASD and cortical surface area through co- localization techniques using existing genome-wide association studies. This study may allow us to understand the mechanism of action of ASD-associated genetic variation, implicating a cell-type and developmental process, which may lead to a more thorough understanding of ASD pathogenesis. In addition, as prenatal exposure to Valproic Acid is a known environmental risk factor for ASD, this study may identify genetic variants that impact responsiveness to Valproic Acid, allowing the prediction of adverse neurodevelopmental effects based on genotype.