Conformational switches of AXIN in Wnt/catenin signalling

Wnt/连环蛋白信号传导中 AXIN 的构象转换

• 批准号: 2440877
• 金额: --
• 依托单位: Institute of Cancer Research
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2440877
• 关键词: Conformational; switches; AXIN; Wnt; catenin

The Wnt/beta-catenin signalling network is highly conserved and controls important events in embryonic development as well as tissue homeostasis throughout life. The magnitude of Wnt/beta-catenin signalling is determined by the levels and activity of the transcriptional coactivator beta-catenin which also, in its second prominent role, mediates cell-cell adhesion, in this case acting at the plasma membrane. The levels of transcriptionally active beta-catenin are constantly being limited through the action of the beta-catenin destruction complex, a multi-protein complex that captures beta-catenin and then sequentially phosphorylates and ubiquitinates it to target it for proteasomal degradation.AXIN is the central scaffolding protein of the destruction complex. It contains two domains, an N-terminal RGS (regulator of G-protein signalling) domain and a C-terminal DIX (Dishevelled and AXIN) domain with an extended linker connecting the two domains. The conformational states of AXIN, their regulated transition and the impact the conformations have on interactions of AXIN with other signalling components are poorly understood. Moreover, it remains unknown whether conformational switching affects the ability of AXIN to polymerise. Using the insect cell/baculovirus system, we have successfully expressed and purified all full-length components of the beta-catenin destruction complex, including AXIN1. This opens up the possibility to study the mutual interactions of destruction complex components and the regulation of these binding events in mechanistic detail. The aim of this project is to understand how post-translational modification of AXIN controls AXIN conformation and oligomerisation status and thereby its ability to assemble protein complexes by binding to components of the beta-catenin destruction complex and Wnt signalosome.The project aims to assess how AXIN conformation is determined by phosphorylation and PARylation, and how in turn these post-translational modifications determine interactions of AXIN with other Wnt/beta-catenin pathway components to control beta-catenin-dependent transcription.

Wnt/beta-catenin信号网络是高度保守的，并控制胚胎发育以及整个生命中组织稳态中的重要事件。 Wnt/beta-catenin信号的大小由转录共激活β-catenin的水平和活性确定，在这种情况下，在这种情况下，在这种情况下，在这种情况下，在这种情况下，在质膜上起作用。通过β-catenin销毁复合物的作用，传递活性β-catenin的水平不断受到限制，β-catenin销毁复合物是一种多蛋白质络合物，可捕获β-catenin，然后依次磷酸化并将其泛素化以靶向它以靶向蛋白酶体降解。它包含两个域，一个N末端RGS（G蛋白信号传导的调节剂）域和一个C末端DIX（DISHEVELED和AXIN）域，其中具有连接两个域的扩展接头。对AXIN的构象状态，它们的调节过渡以及构象对Axin与其他信号传导组件相互作用的影响知之甚少。此外，构象切换是否影响轴敏化的能力仍然尚不清楚。使用昆虫细胞/杆状病毒系统，我们成功地表达并纯化了β-catenin破坏复合物的所有全长成分，包括Axin1。这打开了研究破坏复合成分的相互作用的可能性，并通过机械细节调节了这些结合事件的可能性。该项目的目的是了解Axin的翻译后修饰如何控制Axin的构象和寡聚状态，从而通过与β-Catenin销毁复合物和WNT信号体的组件结合来组装蛋白质复合物来组装蛋白质复合物。具有其他Wnt/beta-catenin途径成分的AXIN来控制β-catenin依赖性转录。