Genetic and Molecular Dissection of Wnt Pathway Activation

项目摘要 进化上保守的Wnt信号转导通路指导细胞增殖和分化 在动物的发育和组织的体内平衡过程中。尽管Wnt信号的失调 是许多发育障碍和癌症的基础，包括几乎所有的结直肠癌，许多 对这些机制仍然知之甚少。因此，更深入地了解激活 该途径将指导新的治疗策略的开发以对抗Wnt驱动的疾病。的 PI研究计划的长期目标是阐明在细胞凋亡过程中激活Wnt信号的机制。 动物的发展，并利用这些知识来确定控制点的途径， Wnt驱动疾病的治疗靶向。为了支持这一努力，PI和她的实验室小组已经 在果蝇中建立了创新的体内模型，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;和ADP-核糖聚合酶， 端锚聚合酶在这些发现的基础上，通过全基因组筛选来发现新的Wnt， 信号调节器，目前的项目将解决三个主要的未解决的问题：1）如何膜- 相关受体激活复合物组装和激活; 2）负调节细胞溶质 β-连环蛋白破坏复合物在Wnt刺激后被抑制;以及3）核β-连环蛋白-TCF如何 转录复合物被激活。为了阐明以前未知的Wnt通路激活剂的作用， 该项目将把遗传学、细胞生物学和生物化学方法与以前的体内试验结合起来 由PI开发，用于监测Wnt信号梯度内的通路激活。它将采用创新的 重点集中在三个组成部分：一个去泛素化的复杂性至关重要的Wnt受体的稳定性，一个泛素 信号传导激活所必需的连接酶和激活β-连环蛋白-TCF转录的激酶 复杂.这项工作得到了与具有这方面专门知识的调查人员进行富有成效的合作的补充。 Wnt信号转导的生化重建，脊椎动物模型中的Wnt通路分析，以及 使用质谱分析鉴定Wnt依赖性翻译后蛋白质修饰。的 这项工作的成功完成将提供以下理解：1）Wnt受体活性的控制; 2） β-连环蛋白破坏复合物的控制; 3）Wnt转录复合物的激活;以及4） 针对Wnt驱动疾病的新治疗策略。

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.