Cellular mechanisms underlying Fgf8-mediated asymmetry of the pharyngeal endoderm

Fgf8介导的咽内胚层不对称性的细胞机制

基本信息

批准号：
10208858
负责人：
Jennifer Leslie Fish
金额：
$ 15.65万
依托单位：
UNIVERSITY OF MASSACHUSETTS LOWELL
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10208858
关键词：
Actins Adherens Junction Affect Alleles Apical Apoptosis Bilateral Birds Branchial arch structure Cell Polarity Cell division Cells Cephalic Chick Cre driver Cytoskeleton Data Defect Development DiGeorge Syndrome Disease susceptibility Distal Ear Ectoderm Elements Embryo Endoderm Epithelial Epithelial Cells Evolution Exhibits Face Facial asymmetry Failure Genetic Genotype Goals Growth Head Heart Abnormalities Jaw Lateral Left Mammals Mediating Mesenchyme Mesoderm Messenger RNA Modeling Morphogenesis Morphology Mus Mutant Strains Mice Outcome Parathyroid gland Pathway interactions Penetrance Pharyngeal pouch Pharyngeal structure Phenotype Positioning Attribute Process Regulation Research Role Series Severities Severity of illness Shapes Side Signal Transduction Skeleton Source Surface Syndrome Testing Thymus Gland Thyroid Gland Tissues Tonsil Tympanic membrane Variant Work Zebrafish cardiogenesis craniofacial craniofacial disorder dosage first pharyngeal pouch migration mutant neonate paracrine skeletal

项目摘要

PROJECT SUMMARY The pharyngeal pouches develop into the thymus, thyroid and parathyroid glands and contribute to formation of the ear and tonsils. They also provide signals that are essential to the morphogenesis of the craniofacial skeleton. In this latter role, the specific morphology and position of the pouches relative to the mesenchyme of the pharyngeal arches is critical to instruct skeletal formation. Despite these essential roles for proper development of the vertebrate head, pharyngeal pouch development in mammals remains poorly understood. Pharyngeal pouch formation consists of two separate morphogenetic processes, lateral out-pocketing and proximal-distal extension. The work outlined in this proposal focuses on understanding the role of Fgf8 in the latter process. Using an allelic series of Fgf8 mutant mice, embryos of different Fgf8 dosages can be generated, including both a mild and severe mutant. In contrast to zebrafish, in both mouse Fgf8 mutant genotypes, the first pharyngeal pouch (pp1) out-pockets to contact the ectoderm but fails to extend along the proximal-distal axis. In mild mutants, pp1 is reduced in size, but does extend. In the severe mutant, pp1 does not extend proximo-distally and the ectodermal cleft is also hypoplastic and disorganized, contributing to failure of the first and second arches to separate distally. Severe mutants have small, round pouches in which cells appear to stack upon each other. Together, these data suggest that Fgf8 has additional roles in pharyngeal pouch formation beyond directing lateral out-pocketing, which may include proximal-distal extension of both the pharyngeal endoderm and ectoderm. Previous research has suggested that Fgf8 regulates cell polarity, and that polarity of the actin cytoskeleton is essential to pharyngeal pouch extension. The specific hypothesis to be tested by the proposed research is that Fgf8 has a paracrine function regulating proliferation and polarity of pharyngeal pouch epithelial cells. This hypothesis will be tested through two specific aims. In Specific Aim 1, proliferation and polarity in pouch epithelial cells will be quantified in embryos in which Fgf8 has been reduced globally. In Specific Aim 2, pouch shape will be evaluated in embryos in which Fgf8 is specifically ablated in the pharyngeal mesoderm or ectoderm. The future research goals of this work are to investigate genetic and developmental interactions underlying variation in craniofacial morphogenesis, particularly variation in the severity and penetrance of craniofacial disorders. The Fgf8 allelic series exhibits a large range of morphological variation, including the bilateral variation present in both mutant genotypes. Both Fgf8 mutant genotypes exhibit directional asymmetry of the jaw, exemplified by Fgf8Neo/Neo mice in which unilateral fusion of the jaw on the left side only is observed in 33% of neonates. Although it has yet to be shown directly, directional asymmetry is likely due bilateral asymmetry in Fgf8 expression in the cranial mesoderm as a consequence of heart development. Facial asymmetry and heart defects are associated in several syndromes, notably CHARGE and DiGeorge (22q11 deletion) syndrome, which have similar phenotypes to Fgf8 mutants.

项目摘要咽袋发育成胸腺，甲状腺和甲状旁腺，并有助于形成耳朵和扁桃体。它们还提供对颅面形态发生必不可少的信号骨骼。在后一种角色中，小袋相对于间质的特定形态和位置咽弓对于指导骨骼形成至关重要。尽管有这些基本角色脊椎动物头的发育，哺乳动物的咽袋发育仍然知之甚少。咽袋形成由两个单独的形态发生过程组成近端扩展。该提案中概述的工作重点是了解FGF8在后一个过程。使用等位基因FGF8突变小鼠，不同FGF8剂量的胚胎可以是产生，包括轻度和重度突变体。与斑马鱼相反，在两个小鼠FGF8突变体中基因型，第一个咽袋（PP1）与外胚层接触但未能沿近端轴。在温和的突变体中，PP1的大小降低，但确实延长了。在严重的突变体中，pp1做不延伸近距离延伸，外胚层裂缝也不塑形且混乱，导致失败第一个和第二个拱门的远端分开。严重的突变体有较小的圆袋，其中细胞似乎彼此堆叠。总之，这些数据表明FGF8在咽中具有额外的作用小袋形成超越指导侧向载运，这可能包括两者的近端扩展咽内胚层和外胚层。先前的研究表明，FGF8调节细胞极性，并且肌动蛋白细胞骨架的极性对于咽袋延伸至关重要。特定的假设可以通过拟议的研究进行测试是，FGF8具有调节增生和极性的旁分泌功能咽袋上皮细胞。该假设将通过两个具体目标进行检验。在特定的目标1中，小袋上皮细胞中的增殖和极性将在FGF8降低的胚胎中进行定量全球。在特定的目标2中，将在胚胎中评估小袋形状，其中FGF8在该胚胎中特别消融咽中胚层或外胚层。这项工作的未来研究目标是研究遗传和颅面形态发生的发展基础变化的发展相互作用，尤其是在颅面疾病的严重程度和外观。 FGF8等位基因系列展示了大量形态变异，包括两个突变基因型中存在的双侧变异。两个FGF8突变体基因型表现出下颌的定向不对称性，以FGF8NEO/NEO小鼠为例，其中单侧融合仅在33％的新生儿中观察到左侧的下颌。尽管尚未直接显示方向性不对称可能是由于颅中胚层中FGF8表达的双侧不对称性作为A 心脏发展的后果。面部不对称和心脏缺陷与多种综合症有关，值得注意的是电荷和Digeorge（22q11缺失）综合征，它们的表型与FGF8突变体相似。