RACK1调控Dishevelled蛋白和Wnt信号的分子机制与生理意义研究

Wnt signaling plays a crucial role in cell proliferation, organ morphogenesis and tissue homeostasis maintenance. As a key component of Wnt signalling pathway, the stability of Dishevelled(Dvl) protein is stringently regulated. In screening of Dvl2 interaction proteins, receptor for activated C kinase 1 (RACK1), a kind of multifunctional adaptor protein, was identified. Our previous data showed that RACK1 could promote Dvl2 degradation, and this phenomenon was much more obvious upon autophagy induction. In this project, we will investigate the regulation of Dvl2 stability and Wnt signaling by RACK1, and explore the underlying molecular mechanisms as well as physiological significance, with combinational use of multiple biology methods. Firstly, we will confirm that RACK1 interacts with Dvl2 and promotes Dvl2 degradation, and also distinguish the degradation pathway. Then more intrinsic evidance should be provided on how the stability of Dvl2 is regulated by RACK1 under autophagy condition. Finally, with the use of colon cancer cell lines and tumor tissues, we will investigate the physiological significance of regulation on Dvl stability and Wnt signalling by RACK1. The results of this project are expected to enrich our understanding on the regulation networks of Dvl proteins and Wnt signaling, especially to provide new insights into Wnt signalling modulation in autophagy condition or cancer cells.

Wnt信号通路在细胞增殖、器官发生、组织稳态维持中发挥着关键作用。作为Wnt通路的核心蛋白，Dishevelled (Dvl)的稳定性受到严格调控。在筛选与Dvl2相互作用的蛋白时，我们发现了一种多功能支架蛋白RACK1。前期结果显示，RACK1能促进Dvl2蛋白降解，且该现象在自噬条件下尤为显著。在本项目中，我们将综合运用多种生物学方法研究RACK1对Dvl2蛋白稳定性和Wnt信号的调控，并深入探讨分子机制和生理意义。研究内容包括：(1) 证实RACK1与Dvl2互作并促进Dvl2蛋白降解的现象，明确降解途径；(2) 基本阐明细胞自噬在RACK1降解Dvl2蛋白过程中的作用与分子机制；(3) 在结肠癌细胞和组织中探究RACK1调控Dvl2蛋白与Wnt信号的生理意义。我们希望本项目能丰富人们对Dvl蛋白和Wnt信号调控网络的认识，尤其对理解自噬条件下或肿瘤细胞中Wnt信号的调控有所帮助。

Wnt信号通路在多个生物过程中发挥重要作用，如胚胎发育、肿瘤发生、细胞增殖和细胞命运决定等。Dvl是Wnt信号通路的中心组分，其稳定性和活性受到严格调控。研究表明，Dvl能够通过蛋白酶体和自噬-溶酶体途径降解。本项目主要以哺乳动物细胞系为实验材料，综合运用生物化学、分子生物学、细胞生物学的多种方法，发现RACK1（激活的蛋白激酶C受体1）能够负调控Dvl蛋白稳定性和Wnt信号通路。RACK1蛋白能够与Dvl相互作用，并促进其通过溶酶体降解，且该现象在诱导细胞自噬后进一步加强。RACK1还能通过两个LIR序列与LC3互作，并增强LC3与Dvl之间的相互作用，从而导致Dvl蛋白通过自噬途径降解。这些发现揭示了RACK1通过改变Dvl稳定性调控Wnt信号的新功能。