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 that 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 the study of PCP. We found that PCP was normal in quintuple mutant wings that rely solely on the 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.

平面细胞极性 (PCP) 组织细胞突起的方向和组织平面内的迁移活动。PCP 的建立涉及核心 PCP 成分的亚细胞极化。有人提出，Wnt 梯度可以提供一个全局线索，将局部 PCP 与组织轴协调。在这里，我们剖析了 Wnt 配体在果蝇毛发定向中的作用翅膀，用于研究 PCP 的既定系统。我们发现 PCP 在五重突变翼中是正常的，这些翼仅依赖于膜系无翼来进行 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。我们得出的结论是，尽管 Wnt 配体可能有助于 PCP，但它们并不是必需的，而且对于组织范围的极化，必须存在另一个全局线索。