Decoding regulatory nodes controlling growth and proportion of the skull

项目总结 头骨由不同胚胎起源的骨骼组成，这些骨骼连接起来包裹大脑，保护 感觉器官，并使咀嚼。精心编排的信号和形态事件生成 颅面复合体的无缝形态。最重要的是颅神经脊细胞。 (CNCC)从前神经皱褶迁移到口咽弓。中核集团收购 来自中脑和后脑分割的轴向同一性。对CNCC基因表达的修饰，其 前体、它们的衍生物、甚至相互作用的组织可能是正常变异和共同变异的基础。 头面部畸形。尽管控制CNCC早期规范的基因调控网络 都是众所周知的，我们仍然缺乏关于涉及CNCC衍生品和 这与疾病的基本机制有何关系。这项提案中概述的实验将取笑 撇开基因型的形态后果不谈。我们预计，基因座改变了 头骨和面部在有颌骨的脊椎动物中具有共性，因为头部是祖先的特征。我们的 先前的系统基因组学比较发现，固定的基因座与不同的发育突起相关。 其中一个确定的区域包含一个包含一个大的顺式调控区域的基因座，该区域高度保守 都是有颌骨的脊椎动物。该基因座位于agap1的一个内含子中，并与Aagap1基因保持定向同源性。 最近的邻居，同源异型盒基因gbx2，覆盖了所有脊椎动物的进化。这个343个碱基对(Bp)区域是 定义为在脊椎动物中有90%以上的同源性。超过190个碱基的核心部分保持100%的同源性 在灵长类动物中，表明通过强大的选择压力保存的深层保护，以及在 人的发展。初步分析表明，该地区可能会参与一个更广泛的监管中心 调节gbx2的表达。因为gbx2对于构图CNCC是必不可少的，并且在 口咽弓，我的假设是我们确定的保守的非编码区作为一个 Gbx2的特定增强剂，调节形成拱形的图案并导致成比例 颌骨突起的变化。我将通过确定组件的功能来验证这一假设 监管中心及其对颌骨的正常生长和形成的贡献。我将分析必要性和 斑马鱼、黑猩猩和人类的同源序列的功能，以及确定gbx2在 头面部形态。成果措施包括对CNCC移民的长期评估和 体内分化，并评价gbx2及其相关同源框DLX时空表达的变化 CNCC及其衍生物中的基因。这些实验的发现将导致改进的临床策略 解决与颌骨生长和形态中断有关的疾病，以及阐明 编码和非编码元素对颅面发育和畸形的影响。

PROJECT SUMMARY The skull is comprised of bones of different embryonic origins that articulate to encase the brain, to protect the sense organs, and to enable mastication. Well-orchestrated signaling and morphological events generate the seamless morphology of the craniofacial complex. Of central importance are the cranial neural crest cells (CNCCs) that migrate from the anterior neural folds to populate the oropharyngeal arches. CNCCs acquire axial identity from midbrain and hindbrain segmentation. Modifications to gene expression of CNCCs, their precursors, their derivatives, or even interacting tissues may underlie both normal variation and common craniofacial malformations. Although the gene regulatory networks that govern early specification of CNCCs are well known, we still lack detailed knowledge of later developmental events involving CNCC derivatives and how this relates to fundamental mechanisms of disease. The experiments outlined in this proposal will tease apart the morphological consequences of genotype. We expect that loci modifying the relative proportions of the skull and face will have commonalities amongst jawed vertebrates, as the head is an ancestral trait. Our prior phylogenomic comparisons identified fixed loci correlated with differential developmental prognathism. One of the regions identified encompasses a locus containing a large, cis-regulatory region highly conserved in all jawed vertebrates. This locus rests in an intron of agap1, and has retained directional synteny with the nearest neighbor, homeobox gene gbx2, over all of vertebrate evolution. This 343 base pair (bp) region is defined as having over 90% identity among vertebrates. A core of over 190bp is retained with 100% identity among primates, suggesting deep conservation preserved by strong selective pressure and a potential role in human development. Preliminary analyses suggest the region may participate in a broader regulatory hub that modulates expression of gbx2. As gbx2 is essential for patterning CNCCs, and is expressed in the oropharyngeal arches, my hypothesis is that the conserved non-coding region we identified acts as a specific enhancer for gbx2, mediating patterning of the forming arches and leading to proportional changes in outgrowth of the jaws. I will test this hypothesis by determining the function of components of the regulatory hub and their contributions to proper growth and form of the jaws. I will analyze necessity and function of orthologous sequences from zebrafish, chimp, and human, as well as determine the role of gbx2 in craniofacial morphology. Outcome measures include long-term assessment of CNCC migration and differentiation in vivo, and evaluating changes to spatiotemporal expression of gbx2 and related homeobox dlx genes in CNCCs and their derivatives. Findings from these experiments will lead to improved clinical strategies addressing disorders with disruptions to growth and form of the jaws as well as shed light on the contribution of coding and non-coding elements to craniofacial development and malformations.