Role of Ectodermal Signals in Limb Bud Outgrowth and Development

外胚层信号在肢芽生长和发育中的作用

• 批准号: 7894876
• 负责人: TREVOR J WILLIAMS
• 金额: $ 36.93万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-17 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7894876
• 关键词: Abdomen; Address; Affect; Alleles; Animal Model; Apical Ectodermal Ridge; Appearance; Child; Clinic; Complex; Congenital Abnormality; Data; Defect; Development; Diagnosis; Ectoderm; Elements; Embryo; Embryonic Development; Event; Exhibits; FGF10 gene; FGF8 gene; Face; Family; Feedback; Felis catus; Fibroblast Growth Factor; Forelimb; Future; Genes; Genetic; Goals; Growth; Heart; Hindlimb; Human; Infant; Knockout Mice; Knowledge; Lateral; Lead; Light; Limb Bud; Limb Development; Limb structure; Mammals; Mechanics; Medicine; Mesenchyme; Modeling; Molecular; Molecular Genetics; Morphogenesis; Mus; Natural regeneration; Newborn Infant; Organ; Organogenesis; Outcome; Parents; Pathology; Pathway interactions; Pattern; Pharmacologic Substance; Phase; Phenotype; Pregnancy loss; Prevention; Process; Quality of life; Reagent; Regulation; Role; Secondary to; Shapes; Signal Pathway; Signal Transduction; Signaling Molecule; Specific qualifier value; Structure; System; Testing; Time; Tissues; Up-Regulation; Vertebrates; Wnt proteins; appendage; computerized data processing; dosage; gain of function; gene interaction; insight; limb regeneration; loss of function; malformation; mouse Cre recombinase; mutant; organ regeneration; prevent; receptor; skeletal; spine bone structure

The development and patterning of an embryo requires coordinate interactions between different tissue layers at appropriate times for successful outcome. Mechanistically, this is driven by a group of conserved signaling molecules, their receptors, and their downstream transcriptional effectors. Disruptions of these molecules and their signaling processes can lead to birth defects and/or pregnancy loss. Although many birth defects have clear environmental and genetic causes, insufficient information exists concerning the mechanisms of development to enable the majority of these defects to be detected or prevented pre-natally. An important goal is to develop animal models of congenital malformations that will lead to mechanistic insight into the diagnosis and treatment of related human birth defects. The process of mammalian limb induction, outgrowth and patterning is a pertinent model that can be used to investigate multiple aspects of development and signaling. The development of the limb relies on reciprocal signaling between cells expressing factors belonging to the Fgf family of secreted molecules, especially Fgf8 and Fgf10. Further evidence has implicated another signaling pathway, involving Wnt proteins and -catenin, in two crucial events during limb development. First, the canonical Wnt signaling pathway is needed for establishment of the initial domain of Fgf10 expression. Second, this pathway is required for formation of the apical ectodermal ridge (AER), which is a major organizing center for limb outgrowth and patterning. Recent evidence indicates that the upregulation of canonical Wnt signaling in the early mouse embryonic ectoderm via the stabilization of -catenin greatly upregulates Fgf8 expression. The consequences of these molecular changes are that limb formation is induced along the entire lateral axis between the forelimb and hindlimb buds. This leads to the appearance of a “unilimb” structure that generates a mechanical constraint on normal axis elongation in the mouse trunk. Two hypotheses were generated by these observations: (1) the up-regulation of Fgf8 is responsible for the majority the limb patterning defects observed in the -catenin gain of function experiment; (2) -catenin gain of function can dispense with the requirement of Fgf10 in limb induction. This application will directly test these two hypotheses using available mouse knockout and transgenic strains and will generate a new Fgf8 gain of function allele that can be used to extend these analyses in future. Ultimately the results of this study will provide new insight into limb induction and patterning as well as provide information into the underlying causes of related human birth defects.

胚胎的发育和图案形成需要不同组织之间的协调相互作用 在适当的时间分层，才能取得成功的结果。从机制上讲，这是由一群保守的 信号分子、它们的受体和它们下游的转录效应器。对这些的破坏 分子及其信号传递过程可能导致出生缺陷和/或妊娠丢失。尽管许多人出生了 缺陷有明显的环境和遗传原因，关于缺陷的信息不足 发展机制，使这些缺陷中的大多数能够在出生前被发现或预防。 一个重要的目标是开发先天畸形的动物模型，这将导致机械洞察力 有关人类出生缺陷的诊断和治疗。 哺乳动物肢体的诱导、生长和构图的过程是一个相关的模型，可以 用于研究发育和信号的多个方面。肢体的发育依赖于 表达属于成纤维细胞生长因子家族分泌分子的因子的细胞之间的相互信号， 尤其是Fgf8和Fgf10。进一步的证据表明还有另一条信号通路，涉及Wnt蛋白 和-连环蛋白，在肢体发育的两个关键事件中。首先，规范的Wnt信号通路是 为建立Fgf10表达的起始域所需。其次，这条途径是 顶端外胚层脊(AER)的形成，它是肢体伸出的主要组织中心和 图案化。最近的证据表明，在早期小鼠中规范的Wnt信号上调 胚胎外胚层通过-连环蛋白的稳定，极大地上调FGF8的表达。后果是什么？ 这些分子变化的一个方面是，肢体的形成是沿着前肢之间的整个侧轴诱导的 还有后肢的花蕾。这导致了“uniimb”结构的出现，该结构产生机械的 约束鼠标躯干中的法线轴伸长。由这些假设产生了两个假设 观察结果：(1)fgf8的上调是导致观察到的肢体花纹缺陷的主要原因。 在功能实验中-连环蛋白的增益；(2)-连环蛋白的功能增益可以省去 FGF10在肢体诱导中的作用。这个应用程序将使用可用的鼠标敲击器直接测试这两个假设 和转基因菌株，并将产生一种新的Fgf8功能等位基因，可用于扩展这些 未来的分析。最终，这项研究的结果将为肢体诱导和构图提供新的见解 以及提供有关人类出生缺陷的潜在原因的信息。