title: Structure-function dissection of the frizzled receptor in Drosophila melanogaster suggests different mechanisms of action in planar polarity and canonical Wnt signaling.
abstract: Members of the Frizzled family of sevenpass transmembrane receptors signal via the canonical Wnt pathway and also via noncanonical pathways of which the best characterized is the planar polarity pathway. Activation of both canonical and planar polarity signaling requires interaction between Frizzled receptors and cytoplasmic proteins of the Dishevelled family; however, there has been some dispute regarding whether the Frizzled-Dishevelled interactions are the same in both cases. Studies looking at mutated forms of Dishevelled suggested that stable recruitment of Dishevelled to membranes by Frizzled was required only for planar polarity activity, implying that qualitatively different Frizzled-Dishevelled interactions underlie canonical signaling. Conversely, studies looking at the sequence requirements of Frizzled receptors in the fruit fly Drosophila melanogaster for canonical and planar polarity signaling have concluded that there is most likely a common mechanism of action. To understand better Frizzled receptor function, we have carried out a large-scale mutagenesis in Drosophila to isolate novel mutations in frizzled that affect planar polarity activity and have identified a group of missense mutations in cytosolic-facing regions of the Frizzled receptor that block Dishevelled recruitment. Interestingly, although some of these affect both planar polarity and canonical activity, as previously reported for similar lesions, we find a subset that affect only planar polarity activity. These results support the view that qualitatively different Frizzled-Dishevelled interactions underlie planar polarity and canonical Wnt signaling.
authors.affiliation: MRC Centre for Developmental and Biomedical Genetics, and Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, United Kingdom. d.strutt@sheffield.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Strutt
authors.forename: Daisy
authors.initials: D
authors.lastname: Madder
authors.forename: Varun
authors.initials: V
authors.lastname: Chaudhary
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Artymiuk
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D000072261:Dishevelled Proteins; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D051157:Frizzled Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D016296:Mutagenesis; D009154:Mutation; D020125:Mutation, Missense; D010641:Phenotype; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D011679:Pupa; D013329:Structure-Activity Relationship; D014921:Wings, Animal / Q000254:growth & development; D060449:Wnt Signaling Pathway
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000072261:Dishevelled Proteins; D029721:Drosophila Proteins; D051157:Frizzled Receptors; D010750:Phosphoproteins; C000606588:dsh protein, Drosophila; C058784:fz protein, Drosophila; C101703:fz2 protein, Drosophila