Analysis of combinatorial effects of Wnts and Frizzleds on beta-catenin/armadillo stabilization and Dishevelled phosphorylation.
Both Wnt ligands and Frizzled (Fz) receptors each constitute a large family in vertebrates, but the receptor specificity of each Wnt has remained largely unknown. Here, we examined the receptor specificity of two typical Wnts, Wnt-3a and Wnt-5a, in signal transmission. To investigate systematically the combinatorial effects of these Wnts, various Fzs on canonical Wnt/beta-catenin signaling, we analyzed the ability of these Wnt proteins to increase stability of armadillo/beta-catenin proteins in Drosophila S2 cells expressing vertebrate Fzs. Wnt-3a increases the amount of armadillo proteins in cells expressing Fzs 4, 5 and 8, but not Fzs 3 and 6; whereas Wnt-5a does not increase it in any cell line. In contrast, both Wnt-3a and Wnt-5a increase the phosphorylation of Dsh in combination with most of the Fzs. This Dsh phosphorylation is abrogated by decreasing the levels of casein kinase I alpha by double-stranded RNA-mediated translational interference. These observations indicate that both Wnt proteins can interact with the majority of Fz receptors and elicit signaling reactions exemplified by Dsh phosphorylation but that the stabilization of beta-catenin/armadillo proteins in the Wnt/beta-catenin signaling occurs only when specific combinations of Wnt and Fz meet.
Takada
Ritsuko
R
Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.
Hijikata
Hiroko
H
Kondoh
Hisato
H
Takada
Shinji
S
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D051186:Armadillo Domain Proteins / Q000378:metabolism*; D047389:Casein Kinase I / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D000072261:Dishevelled Proteins; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism* / Q000494:pharmacology; D051157:Frizzled Receptors / Q000378:metabolism*; D006801:Humans; D051379:Mice; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D034622:RNA Interference; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D051153:Wnt Proteins / Q000494:pharmacology / Q000502:physiology*; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D051176:beta Catenin / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D051186:Armadillo Domain Proteins; D000072261:Dishevelled Proteins; D029721:Drosophila Proteins; D051157:Frizzled Receptors; D010750:Phosphoproteins; D043562:Receptors, G-Protein-Coupled; C555510:WNT3A protein, human; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D051176:beta Catenin; C000606588:dsh protein, Drosophila; C058784:fz protein, Drosophila; D047389:Casein Kinase I