Extracellular regulation of Xenopus development

项目摘要 脊椎动物胚胎的身体计划是通过细胞间的相互作用建立的， 信号通路的数量。这些胚胎衍生分子的知识， 在体外分化小鼠和人类的多能分化细胞中， 干细胞并作为组织工程的基础。在两栖动物中，Wnt信号， BMP、FGF和Nodal相关配体导致Spemann组织者的形成， 随后的组织图案化。许多其他细胞外因子调节时间，位置 和这些信号事件的水平，他们的发现和分析仍然是一个重要的 基础发育生物学的目标。此应用程序的重点是分析针头 （pnhd），我们在Wnt靶基因的筛选中鉴定的保守基因。 过表达和缺失实验表明pnhd在轴向模式中的作用，但其 作用机制目前尚不清楚。其他初步研究表明，Pnhd是一种 一种分泌蛋白，可在区域特异性 方式基于这一证据，Pnhd被假设为一个新的上下文- 胚胎通路的特异性调节剂。拟议中的实验将验证这一点 通过描述Pnhd的发育作用和功能效应物， 与脊椎动物轴的规格和前后图案有关。其他研究 将解决Pnhd对Wnt信号传导的背景依赖性影响的分子基础。 将使用非洲爪蟾胚胎研究Pnhd作用的机制，其中 生物化学和细胞生物学方法可以与快速功能分析相结合 在一个完整的动物的背景下。这些研究将有助于进一步了解 信令网络导致身体计划规范和模式在早期 发展由于Wnt和BMP通路已经涉及许多人类肿瘤， 癌症，拟议的实验将揭示新的分子机制， 在正常的胚胎发育过程中，并且在疾病中经常被破坏。

Project Summary Vertebrate embryo body plan is established through cell-cell interactions driven by a small number of signaling pathways. The knowledge of these embryo-derived molecules and pathways has been instrumental for in vitro differentiation of mouse and human pluripotent stem cells and serves as a basis for tissue engineering. In amphibians, signaling from Wnt, BMP, FGF and Nodal-related ligands results in the formation of the Spemann organizer and subsequent tissue patterning. Many other extracellular factors regulate the time, location and level of these signaling events, and their discovery and analysis remain an important goal of basic developmental biology. This application focuses on the analysis of pinhead (pnhd), a conserved gene that we identified in a screen for Wnt target genes. Overexpression and depletion experiments suggest roles of pnhd in axial patterning, but its mechanism of action is currently unknown. Other preliminary studies show that Pnhd is a secreted protein that modulates Wnt- and BMP-dependent signaling in a region-specific manner. Based on this evidence, Pnhd is hypothesized to function as a new context- specific modulator of embryonic pathways. The proposed experiments will test this hypothesis by characterizing the developmental roles and functional effectors of Pnhd that are relevant to vertebrate axis specification and anteroposterior patterning. Other studies will address the molecular basis of the context-dependent effects of Pnhd on Wnt signaling. The mechanism of Pnhd action will be investigated using Xenopus embryos, in which biochemical and cell biological approaches can be combined with rapid functional analysis in the context of an intact animal. These studies will contribute to further understanding of signaling networks leading to body plan specification and patterning during early development. Since Wnt and BMP pathways have been implicated in many human cancers, the proposed experiments will unravel novel molecular mechanisms that operate during normal embryonic development and become frequently disrupted in disease.