Wnt signaling pathway interactions in early anterior-posterior neuroectoderm patterning

项目总结/摘要 胚胎形成早期神经外胚层沿着前神经外胚层的分子机制， 后（AP）体轴和Wnt信号网络控制多个方面的机制， 发育和成人体内平衡是基本的生物学问题。然而， 发现了这些问题，特别是在后口动物的早期发育过程中， Wnt信号传导对于前-后神经外胚层模式化至关重要的胚胎。我们有 最近发现，3种不同但相互关联的Wnt信号通路形成了一个Wnt网络， 在早期海胆胚胎中，神经外胚层沿着前后轴形成图案是必不可少的。 多个后口类物种之间的功能和表达研究的比较（即，棘皮动物， 半索动物，脊索动物），包括脊椎动物，强烈表明这个Wnt网络的各个方面是 保守的我们实验室研究的长期目标是系统地表征细胞外， 细胞内和转录参与Wnt网络管理早期AP神经外胚层 在海胆中形成图案。这个R15的目的是建立转录基因调控 在Wnt网络下游激活的GRN网络，并进行初步的功能研究， 揭示细胞外和细胞内Wnt调节剂如何影响网络的活性。的 中心假设是在细胞外的信号通路之间存在关键的相互作用， 细胞内和转录水平。基本原理是，通过首先生成转录GRNs， 我们可以更好地了解细胞外和细胞内Wnt网络是如何整合在AP中的， 神经外胚层图案化GRN。Aim 1将揭示由Wnt/JNK激活的转录因子， Wnt/PKC信号通路在AP神经外胚层模式化过程中的作用 筛选比较野生型胚胎与Wnt/JNK和Wnt/PKC敲低胚胎。功能基因 微扰研究将建立转录GRN支架，并确定关键的 在转录水平上的Wnt途径之间的相互作用。目标2将使用基因扰动 分析推定的细胞外和细胞内Wnt调节剂，以便更好地表征 在Wnt/JNK和Wnt/PKC转导通路中使用的通路成员，以鉴定可能的 这些调节剂之间的相互作用的途径，并了解这些调节剂如何影响 在Aim 1中创建的新兴GRN。这项拟议中的研究意义重大，因为它将是为数不多的 进行了系统的研究，以确定这些Wnt网络如何影响体内发育， 模型系统它还将提供基线的比较功能研究的GRN在其他 后口动物模式物种，包括脊椎动物，从而填补了我们的知识的巨大空白， 早期AP模式化机制的演变。

Project Summary/Abstract The molecular mechanisms by which embryos pattern the early neuroectoderm along the anterior- posterior (AP) body axis and the mechanisms by which Wnt signaling networks govern multiple aspects of development and adult homeostasis are fundamental biological questions. However, much remains to be discovered about each of these questions, especially during the early development of deuterostome embryos where Wnt signaling is essential for anterior-posterior neuroectoderm patterning. We have recently discovered that 3 different, but interconnected, Wnt signaling pathways form a Wnt network that is essential for patterning the neuroectoderm along the anterior-posterior axis in early sea urchin embryos. Comparison of functional and expression studies among multiple deuterostome species (i.e., echinoderms, hemichordates, chordates), including vertebrates, strongly suggests that aspects of this Wnt network are conserved. The long-term goal of the studies in our lab is to systematically characterize the extracellular, intracellular and transcriptional players involved in the Wnt network governing early AP neuroectoderm patterning in the sea urchin. The objective of this R15 is to establish the transcriptional gene regulatory network (GRN) activated downstream of the Wnt network and perform initial functional studies to uncover how extracellular and intracellular Wnt modulators influence the activity of the network. The central hypothesis is that there are key interactions among the signaling pathways at the extracellular, intracellular, and transcriptional level. The rationale is that by first generating the transcriptional GRNs we can better understand how the extracellular and intracellular Wnt network are integrated in the AP neuroectoderm patterning GRN. Aim1 will uncover the transcription factors activated by the Wnt/JNK and Wnt/PKC signaling pathways during AP neuroectoderm patterning using information from differential screens comparing wild type embryos with Wnt/JNK and Wnt/PKC knockdown embryos. Functional gene perturbation studies will be performed to establish the transcriptional GRN scaffold and to define key interactions between the Wnt pathways at the transcriptional level. Aim 2 will use gene perturbation analyses on putative extracellular and intracellular Wnt modulators in order to better characterize the pathway members used in the Wnt/JNK and Wnt/PKC transduction pathways, to identify possible interactions among these modulators between the pathways, and to learn how these modulators affect the emerging GRN created in Aim1. The proposed research is significant because it will be one of the few systematic studies conducted to determine how these Wnt networks influence development in an in vivo model system. It will also provide the baseline for comparative functional studies of the GRN in other deuterostome model species, including vertebrates, thereby filling in large gaps in our knowledge of the evolution of early AP patterning mechanisms.