Project III - Modeling meningomyelocele alleles and response to folic acid diet in mouse

摘要-项目III模拟小鼠脑膜脊髓膨出等位基因和对叶酸饮食的反应 该项目资助的总体假设是新生突变导致脊髓脊膜膨出 (MM)叶酸（FA）通过染色质可及性和基因调控影响基因组 #21453;，改变这种风险。小鼠被认为是人类神经管缺陷的金标准模型 （NTD），因为发育在哺乳动物中高度保守，导致类似类型的颅和尾 NTDs，利用相似的基因，并响应相似的环境因素。这只老鼠是无价的 在定义神经管闭合所需的基因，现在超过250个基因，并强调需要 细胞增殖、肌动蛋白调节、平面细胞极性/WNT信号传导、纤毛/Hedgehog的精密度 信号传导和FA代谢。许多小鼠NTD模型显示等位基因特异性效应，例如， 纯合无效小鼠是胚胎致死的，杂合无效小鼠是健康的，但是特定的点突变， 一些杂合子，一些纯合子，显示NTD。在许多这些小鼠模型中，NTD通常发生在更少的 超过100%的后代，即使在一个完全纯的遗传背景，反映背景独立的部分 外显率与人类一样，FA可影响NTD表型的表达率和表达度 暴露，迄今为止测试的基因中约有一半显示出FA反应性。FA已在 自1998年以来，美国饮食中的谷物，调节核苷酸和S-腺苷甲硫氨酸的生物合成， DNA甲基化的甲基供体。为了解释这些观察结果，我们假设NTD风险是 由核心基因组的突变建立，风险由FA依赖性变化改变， 表观基因组项目三已经收集了以下初步数据：1]隐性ENU- 诱变筛选神经管闭合所必需的基因。2]组装了越来越多的基因 和来自30多个NTD突变体的等位基因。3]已证实的初级纤毛基因突变 几种小鼠NTD突变体。4]证明了FA对小鼠NTD的表达率和表达率的影响。 5]开发了活细胞成像平台，用于实时观察哺乳动物神经管闭合。6]建模 人MM基因WLS在小鼠脑膜脊髓膨出中的表达。这项建议的重点是评估基因和 作为MM风险因素的项目I和II中出现的等位基因，以及 甲基化组和转录组可能会影响这种风险。总而言之，项目三的目标是确定 哺乳动物MM突变和FA对突变的影响之间的关系和相互作用， 表现力 目标1.模拟人类脑膜脊髓膨出（MM）变异和遗传相互作用，以评估表达能力。 目标2.评估叶酸对NTD基因表达的影响。 目标3。在单细胞转录组、甲基化组水平上评估叶酸对神经管的影响 和染色质可及性景观。

Abstract – Project III Modeling meningomyelocele alleles and response to folic acid diet in mouse The overall hypothesis of the Program Project grant is that de novo mutations contribute to meningomyelocele (MM) risk and that folic acid (FA) influences the genome through chromatin accessibility and modulation of gene expression, to alter this risk. The mouse is considered the gold standard model for human neural tube defects (NTDs), because development is highly conserved in mammals, leading to similar types of cranial and caudal NTDs, utilizing similar genes, and responding to similar environmental factors. The mouse has been invaluable in defining genes required for neural tube closure, now numbering over 250 genes, and highlighting the need for exquisite precision of cell proliferation, actin regulation, planar cell polarity/WNT signaling, cilia/Hedgehog signaling, and FA metabolism. Many mouse NTD models show allele-specific effects, where for example, homozygous null mice are embryonic lethal, heterozygous null mice are healthy, but specific point mutations, some heterozygous, some homozygous, show NTD. In many of these mouse models, NTDs often occur in less than 100% of offspring, even in an entirely pure genetic background, reflecting background-independent partial penetrance. Like in human, the penetrance and expressivity of NTD phenotypes can be influenced by FA exposure, with about half of genes tested to date showing FA responsiveness. FA has been supplemented in grains in the US diet since 1998, regulating biosynthesis of nucleotides and S-adenosylmethionine, the universal methyl donor for DNA methylation. To account for these observations, we hypothesize that NTD risk is established by mutations in a core set of genes, with risk modified by FA-dependent changes in the epigenome. Project III has already assembled the following preliminary data: 1] Performed recessive ENU- mutagenesis screens for genes essential for neural tube closure. 2] Assembled a growing collection of genes and alleles from more than 30 NTD mutants. 3] Demonstrated mutations in primary ciliary genes underlying several mouse NTD mutants. 4] Demonstrated an impact of FA on penetrance and expressivity of murine NTDs. 5] Developed live-cell imaging platform to observe mammalian neural tube closure in real-time. 6] Modeled meningomyelocele in mouse for the human MM gene WLS. This proposal focuses on evaluating genes and alleles emerging from Project I and II as risk factors for MM, as well as the FA-dependent changes in the methylome and transcriptome that can influence this risk. Altogether, the goal of Project III is to define the relationships and interplay between mammalian MM mutations and FA influences on penetrance and expressivity. Aim 1. Model human meningomyelocele (MM) variants and genetic interactions to assess expressivity. Aim 2. Assess impact of folic acid on NTD expressivity on a gene-by-gene basis. Aim 3. Assess impact of folic acid on the neural tube at the level of single cell transcriptome, methylome and chromatin accessibility landscape.