Mechanisms of folate action during nervous system development

项目摘要 神经管缺陷（NTD）是人类胎儿中最常见的严重出生缺陷， 在美国，新生儿合并发病率约为1/1，000，估计为300，000或更多 全球每年的新生儿神经管畸形是由于胎儿早期神经管闭合不全所致 发展遗传和环境因素的结合似乎调节了神经细胞的形成。 管材.值得注意的是，在怀孕期间补充叶酸可以通过尚不清楚的机制预防NTD。我们最近 已发表的研究表明，叶酸受体1（Folr 1），叶酸摄取系统之一，定位于顶端 非洲爪蟾神经板的表面，是必要的神经板细胞顶端收缩期间， 板块褶皱此外，我们发现Folr 1与粘附连接组分C-钙粘蛋白和β- 提示叶酸信号可能调节神经管形成过程中神经板细胞间的粘附 阵我们的总体研究目标是阐明神经系统疾病的细胞和分子机制， 管形成我们将检验叶酸参与神经细胞形态改变的假设， 通过募集其受体并触发新的动态信号通路，在神经形成期间进行。的 第一个具体目标将在于确定叶酸/Folr 1促进神经细胞凋亡的分子机制。 在神经管形成期间的板细胞顶端缢缩。我们将确定Folr 1的分子机制， 调节神经管形成所必需的细胞粘附重塑。在第二个具体目标中， 发现叶酸/Folr 1募集的信号通路，这是神经板细胞顶端所必需的。 收缩和神经管形成。我们将通过获得和损失的泛素化途径， 函数方法和上位性实验。我们将评估叶酸在细胞粘附分子中的作用， 通过对表达荧光标记蛋白或细胞报告基因的胚胎进行活体成像的细胞骨架动力学 神经管形成过程中的粘附和细胞骨架成分。我们会用最先进的方法 包括免疫沉淀蛋白质组学、超分辨显微镜、细胞骨架和细胞 粘附动力学和光遗传学方法来操纵信号传导途径。虽然叶酸强化 在减少NTD方面一直是一种非常有效的公共卫生措施，缺乏基于机制的理解 NTD的预防导致了对意外后果的普遍关注 补充。最佳叶酸补充，风险人群和叶酸不敏感NTD的治疗是一些 尚未解决的临床问题，等待充分阐明的分子和细胞机制， 叶酸在神经管形成中的潜在作用。

Project summary Neural tube defects (NTDs) are among the most common serious birth defects diagnosed in human fetuses and newborns with a combined incidence of ~1/1,000 in the United States and an estimated of 300,000 or more newborns worldwide each year. NTDs result from the failure of neural tube closure during the early fetal development. A combination of genetic and environmental factors appears to regulate the formation of the neural tube. Notably, folate supplementation during pregnancy prevents NTDs by unclear mechanisms. Our recently published study demonstrates that folate receptor 1 (Folr1), one of folate uptake systems, localizes to the apical surface of Xenopus laevis neural plate and is necessary for neural plate cell apical constriction during neural plate folding. Moreover, we find that Folr1 interacts with adherens junction components, C-cadherin and β- catenin suggesting that folate signaling might regulate neural plate cell-cell adhesion during neural tube formation. Our overall research goal is to elucidate the cellular and molecular mechanisms underlying neural tube formation. We will test the hypothesis that folate participates in the changes in cell shape that neural cells undergo during neurulation by recruiting its receptor and triggering a novel and dynamic signaling pathway. The first specific aim will consist in determining the molecular mechanisms underlying folate/Folr1 promotion of neural plate cell apical constriction during neural tube formation. We will identify the molecular mechanisms of Folr1 regulation of cell adhesion remodeling necessary for neural tube formation. In the second specific aim we will discover the signaling pathways recruited by folate/Folr1 that are necessary for neural plate cell apical constriction and neural tube formation. We will interrogate the ubiquitination pathway through gain and loss of function approaches and epistasis experiments. We will assess the role of folate in cell adhesion molecule and cytoskeletal dynamics by live imaging embryos expressing fluorescently tagged proteins or reporters of cell adhesion and cytoskeletal components during neural tube formation. We will use state-of-the-art methodologies including proteomics of immunoprecipitates, super resolution microscopy, reporters of cytoskeletal and cell adhesion dynamics and optogenetic approaches to manipulate signaling pathways. Although folate fortification has been a highly effective public health measure in reducing NTDs, the lack of mechanism-based understanding of NTD prevention leads to general concerns regarding unintended consequences resulting from supplementation. Optimal folate supplementation, risk groups and treatment of folate-insensitive NTDs are some of the unsolved clinical aspects awaiting for the full elucidation of the molecular and cellular mechanisms underlying folate action in neural tube formation.