Planar cell polarity (PCP) organizes the orientation of cellular protrusions and migratory activity within the tissue plane. PCP establishment involves the subcellular polarization of core PCP components. It has been suggested Wnt gradients could provide a global cue that coordinates local PCP with tissue axes. Here we dissect the role of Wnt ligands in the orientation of hairs of Drosophila wings, an established system for study of PCP. We found that PCP was normal in quintuple mutant wings that rely solely on membrane-tethered Wingless for Wnt signaling, suggesting that a Wnt gradient is not required. We then used a nanobody-based approach to trap Wntless in the endoplasmic reticulum, and hence prevent all Wnt secretion, specifically during the period of PCP establishment. PCP was still established. We conclude that, even though Wnt ligands could contribute to PCP, they are not essential, and another global cue must exist for tissue-wide polarization.

中文翻译：

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没有Wnt配体的卷曲依赖性平面细胞极性

平面细胞极性（PCP）在组织平面内组织细胞突起的定向和迁移活动。PCP建立涉及核心PCP组件的亚细胞极化。已经提出Wnt梯度可以提供协调局部PCP与组织轴的整体提示。在这里，我们剖析了Wnt配体在果蝇翅膀的毛发定向中的作用，果蝇翅膀是PCP研究的成熟系统。我们发现五联突变体翅膀中的PCP是正常的，该突变体翅膀仅依赖于系膜的Wingless进行Wnt信号传导，这表明不需要Wnt梯度。然后，我们使用基于纳米抗体的方法将Wntless捕获在内质网中，从而防止所有Wnt分泌，特别是在PCP建立期间。PCP仍然成立。我们得出结论，