Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, UK; Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield S10 2TN, UK.
Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, UK; Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield S10 2TN, UK.
Curr Biol. 2017 Sep 25;27(18):2784-2797.e3. doi: 10.1016/j.cub.2017.08.016. Epub 2017 Sep 14.
The core planar polarity pathway coordinates epithelial cell polarity during animal development, and loss of its activity gives rise to a range of defects, from aberrant morphogenetic cell movements to failure to correctly orient structures, such as hairs and cilia. The core pathway functions via a mechanism involving segregation of its protein components to opposite cells ends, where they form asymmetric intracellular complexes that couple cell-cell polarity. This segregation is a self-organizing process driven by feedback interactions between the core proteins themselves. Despite intense efforts, the molecular pathways underlying feedback have proven difficult to elucidate using conventional genetic approaches. Here we investigate core protein function during planar polarization of the Drosophila wing by combining quantitative measurements of protein dynamics with loss-of-function genetics, mosaic analysis, and temporal control of gene expression. Focusing on the key core protein Frizzled, we show that its stable junctional localization is promoted by the core proteins Strabismus, Dishevelled, Prickle, and Diego. In particular, we show that the stabilizing function of Prickle on Frizzled requires Prickle activity in neighboring cells. Conversely, Prickle in the same cell has a destabilizing effect on Frizzled. This destabilizing activity is dependent on the presence of Dishevelled and blocked in the absence of Dynamin and Rab5 activity, suggesting an endocytic mechanism. Overall, our approach reveals for the first time essential in vivo stabilizing and destabilizing interactions of the core proteins required for self-organization of planar polarity.
核心平面极性途径在动物发育过程中协调上皮细胞极性，其活性丧失会导致一系列缺陷，从异常形态发生细胞运动到无法正确定向结构，如毛发和纤毛。核心途径通过一种涉及将其蛋白成分分离到相反细胞末端的机制发挥作用，在那里它们形成不对称的细胞内复合物，将细胞极性偶联起来。这种分离是一个自我组织的过程，由核心蛋白本身之间的反馈相互作用驱动。尽管进行了大量努力，但使用传统遗传方法证明难以阐明反馈的分子途径。在这里，我们通过结合定量测量蛋白动力学与功能丧失遗传学、嵌合体分析和基因表达的时间控制，研究了果蝇翅膀平面极化过程中核心蛋白的功能。我们关注关键核心蛋白 Frizzled，表明其稳定的连接定位受核心蛋白 Strabismus、Dishevelled、Prickle 和 Diego 的促进。特别是，我们表明 Prickle 对 Frizzled 的稳定作用需要相邻细胞中的 Prickle 活性。相反，同一细胞中的 Prickle 对 Frizzled 具有去稳定作用。这种去稳定作用依赖于 Dishevelled 的存在，并且在 Dynamin 和 Rab5 活性缺失的情况下被阻断，表明存在一种内吞作用机制。总的来说，我们的方法首次揭示了核心蛋白自我组织平面极性所需的体内稳定和去稳定相互作用。
