Molecular mechanisms regulating cranial sensory development

项目摘要 在世界范围内，超过三分之一的先天性出生缺陷被归类为头面部疾病。这些 疾病的表现形式多种多样，从面部特征的异常形成，如下巴或腭部，到受损。 感官功能。尽管在外科重建方面取得了进展，但人们对 作为不同表型基础的分子病理生理学。四种多能细胞系是前驱细胞 到所有类型的颅面细胞，形成于胚胎的前部区域，称为神经板边缘。这个 中央--大多数血统--胎盘前和神经脊--对颅面发育尤其关键， 胎盘前细胞产生支持细胞和感觉神经细胞类型，而神经脊细胞成为 周围神经系统的神经元和神经胶质细胞以及所有面部结构的骨骼和软骨。还没有 确定导致胎盘前和神经峰谱系最初分离的因素一直是 这很困难，因为这两个群体密切混杂在一起。因此，这项研究的目的是使用一种基因谱系- 追踪方法分离胎盘前和牙冠血统并研究两个候选基因的作用 胎盘前规格的分子。我们的实验室先前发现foxI3转录因子是 FoxI3基因的缺失主要影响胎盘来源 结构，包括内耳的丧失。用Foxi3Creer条件记者进行初步血统追踪 实验室产生的小鼠品系显示，正常的foxI3表达的边缘细胞大多成为胎盘 衍生物，但一些突变细胞呈现出不同的边界血统命运。根据这些数据，我们假设 FoxI3直接指定胎盘前血统。我们将通过进一步分析 FOXI3突变边界细胞，对我们的Foxi3Creer小鼠进行谱系追踪。我们还将使用单细胞 用多组学方法评估foxI3功能缺失的同时转录和表观遗传变化 边界单元格。细胞外信号也影响边界谱系：值得注意的是，BMP信号已知能诱导 神经脊细胞。考虑到CREST和胎盘前细胞暴露于相似的BMP水平，我们 假设BMP也影响胎盘细胞规格。我们将通过体内的一种基因来验证这一假设 针对胎盘前(Foxi3Creer)和牙冠(Zic5Creer)边缘细胞的BMP操作。我们的工作 介绍了第一种分离和研究哺乳动物胎盘前血统的方法，并将对 决定神经板边缘细胞命运的关键因素。我们还将深入了解分子变化， 促进边界上的命运转变，有可能识别其突变可能导致 对头面部发育的特定类型的干扰。

Project Summary Worldwide, more than a third of congenital birth defects are classified as craniofacial disorders. These disorders present diversely, from abnormal formation of facial features such as the jaw or palate, to impaired sensory function. Despite advances in surgical reconstruction, there is still a poor understanding of the molecular pathophysiology that underlies distinct phenotypes. Four multipotent cell lineages are the precursors to all craniofacial cell types, forming in an anterior region of the embryo known as the neural plate border. The central-most lineages— pre-placodal and neural crest— are especially key to craniofacial development, with pre-placodal cells giving rise to supporting and sensorineural cell types, while neural crest cells become the neurons and glia of the peripheral nervous system and the bones and cartilage of all facial structures. Yet identifying the factors responsible for the initial segregation of pre-placodal and neural crest lineages has been difficult, given that the two populations intermingle closely. This study thus aims to use a genetic lineage- tracing approach to isolate the pre-placodal and crest lineages and investigate the roles of two candidate molecules in pre-placodal specification. Our lab previously discovered that the Foxi3 transcription factor is transiently expressed in border cells and that genetic deletion of Foxi3 primarily affects placode-derived structures, including loss of the inner ear. Preliminary lineage tracing with a Foxi3CreER conditional reporter mouse line generated in the lab revealed that normal Foxi3-expressing border cells mostly become placode derivatives, but some mutant cells take on alternative border lineage fates. From this data, we hypothesize that Foxi3 directly specifies the pre-placodal lineage. We will test this hypothesis by further analyzing the fate of Foxi3 mutant border cells, using lineage tracing with our Foxi3CreER mice. We will also use a single-cell multiomic approach to assess concurrent transcriptional and epigenetic changes in Foxi3 functionally null border cells. Extracellular signaling also influences border lineages: notably, BMP signals are known to induce neural crest cells. Given the similar BMP levels to which crest and pre-placodal cells are exposed, we hypothesize that BMP also affects placode cell specification. We will test this hypothesis by an in vivo, genetic manipulation of BMP targeted to pre-placodal (Foxi3CreER) versus crest (Zic5CreER) border cells. Our work introduces the first method to isolate and study the mammalian pre-placodal lineage and will shed light on critical factors that direct neural plate border cell fate. We will also gain insight to molecular changes that facilitate fate transitions at the border, with the potential to identify genes whose mutation could result in specific kinds of disruption to craniofacial development.