Extracellular regulation of Xenopus development

项目摘要 脊椎动物的胚胎体计划是通过细胞间的相互作用建立的，由一个小的 信号通路的数量。这些胚胎衍生分子的知识和 通路在小鼠和人类多能性的体外分化中起到了重要作用 干细胞，并作为组织工程的基础。在两栖动物中，来自WNT的信号， 骨形态发生蛋白、成纤维细胞生长因子和结节相关配体导致Spemann组织者和 随后的组织构图。许多其他细胞外因素调节着时间、位置 这些信号事件的级别，以及它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。本应用主要针对针头的分析。 (Pnhd)，这是我们在Wnt靶基因筛选中发现的一个保守基因。 过度表达和耗竭实验表明，pnhd在轴向图案化中起作用，但其 其作用机制目前尚不清楚。其他初步研究显示，Pnhd是一个 分泌蛋白，调节Wnt和BMP依赖的区域特异性信号传导 举止。根据这一证据，Pnhd被假设为一种新的上下文- 胚胎通路的特殊调节物。拟议中的实验将验证这一点。 通过描述Pnhd的发育角色和功能效应器的假说 与脊椎动物的轴线规格和前后图案有关。其他研究 将解决Pnhd对Wnt信号的上下文相关影响的分子基础。 Pnhd的作用机制将利用非洲爪哇胚胎进行研究，其中 生化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 在早期导致身体计划规范和图案的信令网络 发展。由于WNT和BMP通路在许多人类中都有牵连 癌症，拟议中的实验将揭开新的分子机制的运作 在正常的胚胎发育期间，经常在疾病中被破坏。

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.