MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
University of Sheffield, School of Biosciences, Firth Court , Western Bank, Sheffield, S10 2TN, UK.
J Cell Sci. 2022 Jun 1;135(11). doi: 10.1242/jcs.259547. Epub 2022 May 31.
Dishevelled is a cytoplasmic hub that transduces Wnt signals to cytoplasmic effectors, which can be broadly characterised as canonical (β-catenin dependent) and noncanonical, to specify cell fates and behaviours during development. To transduce canonical Wnt signals, Dishevelled binds to the intracellular face of Frizzled through its DEP domain and polymerises through its DIX domain to assemble dynamic signalosomes. Dishevelled also contains a PDZ domain, whose function remains controversial. Here, we use genome editing to delete the PDZ domain-encoding region from Drosophila dishevelled. Canonical Wingless signalling is entirely normal in these deletion mutants; however, they show defects in multiple contexts controlled by noncanonical Wnt signalling, such as planar polarity. We use nuclear magnetic resonance spectroscopy to identify bona fide PDZ-binding motifs at the C termini of different polarity proteins. Although deletions of these motifs proved aphenotypic in adults, we detected changes in the proximodistal distribution of the polarity protein Flamingo (also known as Starry night) in pupal wings that suggest a modulatory role of these motifs in polarity signalling. We also provide new genetic evidence that planar polarity relies on the DEP-dependent recruitment of Dishevelled to the plasma membrane by Frizzled.
Dvl 是一个细胞质枢纽，将 Wnt 信号转导至细胞质效应物，这些效应物可以广义地分为经典（β-catenin 依赖性）和非经典，以在发育过程中指定细胞命运和行为。为了转导经典的 Wnt 信号，Dvl 通过其 DEP 结构域与 Frizzled 的细胞内表面结合，并通过其 DIX 结构域聚合以组装动态信号体。Dvl 还含有一个 PDZ 结构域，其功能仍存在争议。在这里，我们使用基因组编辑从果蝇 Dvl 中删除 PDZ 结构域编码区域。这些缺失突变体中的经典 Wingless 信号完全正常；然而，它们在多个由非经典 Wnt 信号控制的情况下表现出缺陷，例如平面极性。我们使用核磁共振波谱学来鉴定不同极性蛋白 C 末端的真正 PDZ 结合基序。尽管这些基序的缺失在成年个体中表现为表型，但我们在蛹翅中检测到极性蛋白 Flamingo（也称为 Starry night）的近-远分布发生了变化，这表明这些基序在极性信号中具有调节作用。我们还提供了新的遗传证据，表明平面极性依赖于 Frizzled 通过 DEP 依赖性招募 Dvl 到质膜。
