Abstract
We demonstrate that Dvl-1, casein kinase I epsilon (CKI epsilon), and Frat-1 activate the Wnt signaling pathway cooperatively. The amino acid region 228-250 of Dvl-1 was necessary for its binding to Frat-1, and the interaction of Dvl-1 with Frat-1 was enhanced by CKI epsilon. Coexpression of Dvl-1 and Frat-1 caused accumulation of beta-catenin synergistically in L cells. Both proteins also activated the transcriptional activity of T-cell factor-4 (Tcf-4) synergistically in human embryonic kidney 293 cells, but coexpression of Dvl-1-(Delta 228-250), which lacks the amino acid region 228-250 from Dvl-1, and Frat-1 did not. Dvl-1, but not Dvl-1-(Delta 228-250), acted synergistically with CKI epsilon to activate Tcf-4. Depletion of CKI epsilon by double-stranded RNA interference in HeLa S3 cells led to the inhibition of Wnt-3a-induced phosphorylation of Dvl and the binding of Dvl-1 to Frat-1. Furthermore, depletion of CKI epsilon reduced the Wnt-3a-induced accumulation of beta-catenin, although it did not affect the basal level of beta-catenin. These results indicate that CKI epsilon-dependent phosphorylation of Dvl enhances the formation of a complex of Dvl-1 with Frat-1 and that this complex leads to the activation of the Wnt signaling pathway.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Animals
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COS Cells
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Carrier Proteins*
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Casein Kinases
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Cell Line
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Cytoskeletal Proteins / metabolism*
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DNA, Complementary / metabolism
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Dishevelled Proteins
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Gene Deletion
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Genes, Dominant
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HeLa Cells
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Humans
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Immunohistochemistry
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Intracellular Signaling Peptides and Proteins
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Luciferases / metabolism
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Mutation
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Neoplasm Proteins*
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Phenotype
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Phosphoproteins / metabolism*
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Phosphorylation
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Plasmids / metabolism
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Protein Binding
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Protein Kinases / metabolism*
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Protein Kinases / physiology*
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Protein Structure, Tertiary
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Proteins / metabolism*
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Proto-Oncogene Proteins / metabolism*
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RNA Interference
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RNA, Double-Stranded
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Signal Transduction
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TCF Transcription Factors
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Trans-Activators / metabolism*
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Transcription Factor 7-Like 2 Protein
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Transcription Factors / metabolism
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Transcription, Genetic
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Wnt Proteins
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Wnt3 Protein
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Wnt3A Protein
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Xenopus
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Xenopus Proteins*
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beta Catenin
Substances
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Adaptor Proteins, Signal Transducing
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CTNNB1 protein, Xenopus
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CTNNB1 protein, human
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Carrier Proteins
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Cytoskeletal Proteins
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DNA, Complementary
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DVL1 protein, Xenopus
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DVL1 protein, human
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Dishevelled Proteins
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FRAT1 protein, human
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Intracellular Signaling Peptides and Proteins
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Neoplasm Proteins
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PIAS1 protein, Xenopus
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Phosphoproteins
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Proteins
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Proto-Oncogene Proteins
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RNA, Double-Stranded
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TCF Transcription Factors
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TCF7L2 protein, human
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Trans-Activators
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Transcription Factor 7-Like 2 Protein
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Transcription Factors
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WNT3A protein, Xenopus
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WNT3A protein, human
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Wnt Proteins
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Wnt3 Protein
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Wnt3A Protein
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Xenopus Proteins
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beta Catenin
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tcf7l2 protein, Xenopus
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Luciferases
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Protein Kinases
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Casein Kinases