The role of the Foxi3 transcription factor in craniofacial microsomia

项目总结 颅面畸形是最常见的出生缺陷之一。虽然唇裂和/或腭裂和 颅面融合是最常见的颅面畸形，颅面巨大症(CFM)估计为 第三个最常见的颅骨畸形，发生在3000-1/6000活产儿之间。尽管 CFM的症状可以在严重程度上有很大的不同，它们具有与异常一致的各种特征 第一和第二咽弓的发育，包括下颌缩短，小耳， 耳前标记和球上皮样。这些缺陷是典型的，但不完全是单方面的， 尽管一些表现为CFM的家系已被确认，但大多数被认为是散发性的，没有 基因诊断。理解CFM起源的困难包括它的异质性，缺乏明确的 这些疾病的潜在分子机制和良好的动物模型的匮乏。 我们已经鉴定出一种转录因子foxI3，它在咽外胚层中早期和广泛表达。 和内胚层，后来仅限于咽囊和裂隙。FoxI3突变小鼠表现出严重的 大多数咽弓衍生品的缺陷-例如，突变体缺乏大部分下巴，并有一个 中耳听小骨和外耳完全丧失。最近，我们的同事发现了20多个人类 FoxI3基因变异与包括CFM和小耳畸形在内的头面部缺陷相关，以及我们的初步数据 这表明这些缺陷可以在携带其中一些变体的小鼠身上建模。此外，GATA3 转录因子在全基因组关联研究中与cfm相关，共表达。 在几个发育中的脑组织中含有foxI3，最近也被证明能引起CFM表型 当在老鼠身上发生突变时。这增加了foxI3和GATA3在颅面部发生遗传相互作用的可能性 发展。 在这个提案中，我们将首先尝试使用在我们的 我们的合作者描述了Lab和GATA3突变的等位基因。第二，我们将执行一项生物信息学 通过基因表达分析分析foxI3和GATA3控制的基因调控网络 来自foxI3纯合子突变、杂合突变和野生型小鼠的咽部组织，并通过 对咽部组织进行切割和扫描，以确定foxI3和GATA3的直接靶点。最后，我们会 通过对foxI3进行有条件的缺失，阐明foxI3在颅面部早期发育中的作用 咽外胚层和内胚层在正常颅面发育中的作用 每一种组织。

PROJECT SUMMARY Craniofacial abnormalities are some of the most common birth defects. Although cleft lip and/or palate and craniosynostosis are the most common craniofacial defects, craniofacial microsomia (CFM) is estimated to be the third most prevalent cranial anomaly, occurring at between 1 in 3000 – 1 in 6000 live births. Although the symptoms of CFM can vary widely in severity, they share a variety of features consistent with abnormal development of first and second pharyngeal arches, including a shortening of the mandible, microtia, preauricular tags and epibulbar dermoids. These defects are typically, but not exclusively unilateral, and although some families presenting with CFM have been identified, most are considered sporadic and have no genetic diagnosis. Difficulties in understanding the origins of CFM include its heterogeneity, the lack of clear underlying molecular mechanisms and the paucity of good animal models for these disorders. We have identified a transcription factor, Foxi3, that is expressed early and broadly in pharyngeal ectoderm and endoderm, and is later restricted to the pharyngeal pouches and clefts. Foxi3 mutant mice show severe defects in most pharyngeal arch derivatives – for example, the mutants lack much of the lower jaw, and have a complete loss of the middle ear ossicles and the external ear. Recently, our colleagues found over 20 human variants in Foxi3 associated with craniofacial defects including CFM and microtia, and our preliminary data suggests these defects can be modeled in mice carrying some of these variants. Moreover, the Gata3 transcription factor, which has been associated with CFM in genome-wide association studies, is co-expressed with Foxi3 in several developing cranial tissues and has also recently been shown to cause CFM phenotypes when mutated in mice. This raises the possibility that Foxi3 and Gata3 interact genetically during craniofacial development. In this proposal, we will first attempt to create a mouse model of CFM using Foxi3 mutant alleles created in our lab and Gata3 mutant alleles characterized by our collaborators. Second, we will perform a bioinformatic analysis of the gene regulatory networks controlled by Foxi3 and Gata3, by analyzing gene expression in pharyngeal tissue from Foxi3 homozygous mutants, heterozygous mutant and wild type mice, and by performing CUT&RUN on pharyngeal tissue to identify direct targets of Foxi3 and Gata3. Finally, we will address the role of Foxi3 during early craniofacial development by performing conditional deletions of Foxi3 in pharyngeal ectoderm and endoderm and determining its contribution to normal craniofacial development in each tissue.