Genetic and Molecular Dissection of Wnt Pathway Activation

项目总结 进化保守的Wnt信号转导通路指导细胞的增殖和分化 在动物发育和组织动态平衡期间。尽管放松对WNT信号的管制 导致许多发育障碍和癌症，包括几乎所有的结直肠癌，许多 这些机制仍然知之甚少。因此，对激活的机制有了更深的理解 这一途径将指导新的治疗策略的发展，以对抗WNT驱动的疾病。这个 PI研究计划的长期目标是阐明激活Wnt信号的机制 动物的发育，并利用这一知识来确定易感途径中的控制点 WNT驱动疾病的治疗靶向。为了支持这一努力，PI和她的实验室小组 在果蝇体内建立的创新模型揭示了三个核心蛋白的意想不到的功能 WNT途径效应物：肿瘤抑制因子APC；支架蛋白Axin；以及ADP-核糖聚合酶， Tankyrase。建立在这些发现的基础上，并由旨在发现新WNT的全基因组屏幕实现 目前的项目将解决三个尚未解决的主要问题：1)膜如何- 相关受体激活复合体的组装和激活；2)胞浆负性调节如何 β-连环蛋白破坏复合体在Wnt刺激下被抑制；以及3)核β-连环蛋白-TCF如何 转录复合体被激活。为了阐明以前未知的Wnt途径激活物的作用，这 该项目将把遗传、细胞生物学和生化方法与先前的体内分析相结合 由PI开发，用于监测Wnt信号梯度内的通路激活。它将应用一种创新的 焦点集中在三个成分上：Wnt受体稳定所必需的去泛素复合体，泛素 信号激活所必需的连接酶，以及激活β-连环蛋白-TCF转录的激酶 很复杂。这项工作得到了与具有专业知识的调查人员富有成效的合作的补充 脊椎动物模型中Wnt信号的生化重建、Wnt途径分析 利用质谱学分析鉴定依赖Wnt的翻译后蛋白质修饰。这个 这项工作的成功完成将提供对以下方面的理解：1)控制Wnt受体活性；2) β-连环蛋白破坏复合体的控制；3)Wnt转录复合体的激活；以及4) 针对WNT驱动的疾病的新治疗策略。

PROJECT SUMMARY The evolutionarily-conserved Wnt signal transduction pathway directs cell proliferation and differentiation during animal development and tissue homeostasis. Despite the fact that deregulation of Wnt signaling underlies numerous developmental disorders and cancers, including nearly all colorectal cancers, many of these mechanisms remain poorly understood. Thus, a deeper understanding of the mechanisms that activate this pathway will guide the development of new therapeutic strategies to combat Wnt-driven diseases. The long-term goal of the PI’s research program is to elucidate the mechanisms that activate Wnt signaling during animal development and to use this knowledge to identify control points in the pathway susceptible to therapeutic targeting in Wnt-driven diseases. In support of this effort, the PI and her laboratory group have established innovative in vivo models in Drosophila that have revealed unanticipated functions of three core Wnt pathway effectors: the tumor suppressor, APC; the scaffold protein, Axin; and the ADP-ribose polymerase, Tankyrase. Building on these findings and enabled by genome-wide screens designed to uncover new Wnt signaling regulators, the current project will address three major unsolved questions: 1) how the membrane- associated receptor activation complex is assembled and activated; 2) how the negative regulatory cytosolic beta-catenin destruction complex is inhibited upon Wnt stimulation; and 3) how the nuclear beta-catenin-TCF transcription complex is activated. To elucidate the role of previously unknown Wnt pathway activators, this project will couple genetic, cell biological and biochemical approaches with in vivo assays previously developed by the PI to monitor pathway activation within Wnt signaling gradients. It will apply an innovative focus centered on three components: a deubiquitinating complex essential for Wnt receptor stability, a ubiquitin ligase essential for signaling activation, and a kinase that activates the beta-catenin-TCF transcription complex. This work is complemented by productive collaborations with investigators who have expertise in the biochemical reconstitution of Wnt signaling, Wnt pathway analysis in vertebrate models, and in the identification of Wnt-dependent post-translational protein modifications using mass spectrometry analysis. The successful completion of this work will provide an understanding of: 1) the control of Wnt receptor activity; 2) the control of the beta-catenin destruction complex; 3) the activation of the Wnt transcription complex; and 4) novel therapeutic strategies to target Wnt-driven diseases.