Establishing the axial-specific regulatory role of Hoxa2 in mouse cranial neural crest cell development

项目摘要 颅面缺陷和疾病，如唇腭裂和Treacher柯林斯综合征， 降低受影响个体的生活质量。这种缺陷通常是由制造过程中的问题引起的。 颅神经嵴细胞（cNCC）的发育，cNCC是胚胎的、多能的、迁移的细胞， 上升到骨头、结缔组织和头部的神经。为颅面疾病开发微创治疗方法 缺陷，必须首先确定造成这些缺陷的发育过程中的中断。无犯罪 起源于胚胎发育中的大脑附近，然后迁移到面部神经， 鳃弓（BAs）。cNCC的每个亚群产生不同的颅面结构。CNCC， 迁移到BAI（最前面的BA）产生颌骨和一些中耳结构， 那些迁移到BAII的形成其他耳结构和颈部的舌骨。许多基因 已经确定了对cNCC发育重要的基因，但负责模式化的轴向特异性基因 具体的衍生物尚未被广泛研究。 某些颅面缺陷，包括耳畸形、腭裂和伊格尔综合征（茎突舌骨 当迁移到BAII中的cNCC形成通常来源于BAI的结构时，观察到 cNCC导致颅面发育不正常尽管已知Hoxa 2表达转换为 BAI“基态”与BAII cNCC同一性，经常导致缺陷或死亡， 该过程的机制尚未阐明，并且很少有基因与Hoxa 2相互作用以产生 这种表型已经被表征。 这项研究旨在确定基因之间的调控关系，赋予轴特异性 与BAI和BAII中的cNCC的同一性，并建立Hoxa 2塑造BAI和BAII中的cNCC的分子机制。 使用小鼠作为哺乳动物模型系统的BAII cNCC的衍生物。目的1将比较转录 BAI和BAII中cNCC的谱和全基因组染色质状态，以鉴定基因及其增强子 似乎以轴向特定的方式起作用。目的2将比较来自野生型和Hoxa 2-的BAII cNCC。 无效胚胎，并测定这些细胞中的Hoxa 2结合，以确定Hoxa 2负责 将BAII身份赋予cNCC。总之，这些数据将扩展我们对潜在的 发展过程和人类颅面缺陷的病因学，使该领域更接近发展 微创治疗这些疾病。

Project Summary Craniofacial defects and disorders such as cleft lip/palate and Treacher Collins Syndrome frequently decrease the quality of life for affected individuals. Such defects are often caused by problems in the development of cranial neural crest cells (cNCCs), which are embryonic, multipotent, migratory cells that gives rise to bones, connective tissues, and nerves of the head. To develop less invasive treatments for craniofacial defects, it is essential to first identify the disruptions in developmental processes that cause them. cNCCs originate adjacent to the developing brain of the embryo, and then migrate into the facial prominences and branchial arches (BAs). Each subpopulation of cNCCs gives rise to distinct craniofacial structures. cNCCs that migrate into BAI (the anterior-most BA) give rise to the bones of the jaw and some middle ear structures, while those migrating into BAII form other ear structures and the hyoid bone of the neck. A number of genes important for cNCC development have been identified, but axial-specific genes responsible for patterning specific derivatives have not yet been extensively studied. Certain craniofacial defects, including ear malformation, cleft palate, and Eagle’s syndrome (stylohyoid syndrome) are observed when cNCCs that migrate into BAII form structures that are typically derived from BAI cNCCs, leading to improper craniofacial development. Although it is known that Hoxa2 expression transforms the BAI “ground state” to a BAII cNCC identity, frequently resulting in defects or death, the molecular mechanism of this process has not been elucidated, and very few genes that interact with Hoxa2 to produce this phenotype have been characterized. This study seeks to identify the regulatory relationships between genes that are confer axial-specific identity to cNCCs in BAI and BAII, and to establish the molecular mechanism(s) by which Hoxa2 shapes the derivatives of BAII cNCCs using the mouse as a mammalian model system. Aim 1 will compare transcriptional profiles and genome-wide chromatin states of cNCCs in BAI and BAII to identify genes and their enhancers that appear to be acting in an axial-specific manner. Aim 2 will compare BAII cNCCs from wildtype and Hoxa2- null embryos and assay Hoxa2 binding in these cells to determine the extent to which Hoxa2 is responsible for conferring BAII identity to cNCCs. Together, these data will extend our understanding of the underlying developmental processes and etiology of human craniofacial defects and bring the field closer to developing minimally invasive treatments for these conditions.