Laboratory of WNT Signaling, Institute of Experimental Biology, Faculty of Science, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic; Laboratory of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz väg 2, 17177, Stockholm, Sweden.
Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, SE-75124 Uppsala, Sweden.
Cell Signal. 2017 Oct;38:85-96. doi: 10.1016/j.cellsig.2017.06.018. Epub 2017 Jun 29.
Frizzleds (FZDs) are unconventional G protein-coupled receptors, which activate diverse intracellular signaling pathways via the phosphoprotein Disheveled (DVL) and heterotrimeric G proteins. The interaction interplay of FZDs with DVL and G proteins is complex, involves different regions of FZD and the potential dynamics are poorly understood. In the present study, we aimed to characterize the function of a highly conserved tyrosine (Y250) in the intracellular loop 1 (IL1) of human FZD. We have found Y250 to be crucial for DVL2 interaction and DVL2 translocation to the plasma membrane. Mutant FZD-Y250F, impaired in DVL2 binding, was defective in both β-catenin-dependent and β-catenin-independent WNT signaling induced in Xenopus laevis embryos. The same mutant maintained interaction with the heterotrimeric G proteins Gα and Gα and was able to mediate WNT-induced G protein dissociation and G protein-dependent YAP/TAZ signaling. We conclude from modeling and dynamics simulation efforts that Y250 is important for the structural integrity of the FZD-DVL, but not for the FZD-G protein interface and hypothesize that the interaction network of Y250 and H348 plays a role in specifying downstream signaling pathways induced by the receptor.
卷曲蛋白（FZDs）是非常规的 G 蛋白偶联受体，通过磷酸化蛋白 Disheveled（DVL）和异三聚体 G 蛋白激活多种细胞内信号通路。FZD 与 DVL 和 G 蛋白的相互作用复杂，涉及 FZD 的不同区域，其潜在动力学尚不清楚。在本研究中，我们旨在表征人类 FZD 细胞内环 1（IL1）中高度保守的酪氨酸（Y250）的功能。我们发现 Y250 对于 DVL2 相互作用和 DVL2 向质膜的易位至关重要。在 DVL2 结合中受损的突变 FZD-Y250F 在非洲爪蟾胚胎中β-连环蛋白依赖性和β-连环蛋白非依赖性 WNT 信号诱导中均存在缺陷。相同的突变与异三聚体 G 蛋白 Gα和 Gα保持相互作用，并能够介导 WNT 诱导的 G 蛋白解离和 G 蛋白依赖性 YAP/TAZ 信号。我们从建模和动力学模拟工作中得出结论，Y250 对于 FZD-DVL 的结构完整性很重要，但对于 FZD-G 蛋白界面不重要，并且假设 Y250 和 H348 的相互作用网络在受体诱导的下游信号通路特异性中起作用。
