Casein kinase I epsilon enhances the binding of Dvl-1 to Frat-1 and is essential for Wnt-3a-induced accumulation of beta-catenin.
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.
Hino
Shin-ichiro
S
Department of Biochemistry, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Japan.
Michiue
Tatsuo
T
Asashima
Makoto
M
Kikuchi
Akira
A
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins; D047388:Casein Kinases; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D000072261:Dishevelled Proteins; D017353:Gene Deletion; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000378:metabolism; D009154:Mutation; D009363:Neoplasm Proteins; D010641:Phenotype; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism* / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D034622:RNA Interference; D012330:RNA, Double-Stranded; D015398:Signal Transduction; D051820:TCF Transcription Factors; D015534:Trans-Activators / Q000378:metabolism*; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D014981:Xenopus; D029867:Xenopus Proteins; D051176:beta Catenin
D048868:Adaptor Proteins, Signal Transducing; C495266:CTNNB1 protein, Xenopus; C495270:CTNNB1 protein, human; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; C000606586:DVL1 protein, Xenopus; C000606578:DVL1 protein, human; D000072261:Dishevelled Proteins; C491819:FRAT1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; C112892:PIAS1 protein, Xenopus; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012330:RNA, Double-Stranded; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D015534:Trans-Activators; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors; C555506:WNT3A protein, Xenopus; C555510:WNT3A protein, human; D051153:Wnt Proteins; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D029867:Xenopus Proteins; D051176:beta Catenin; C544896:tcf7l2 protein, Xenopus; D008156:Luciferases; D011494:Protein Kinases; D047388:Casein Kinases