title: Interaction and functional cooperation between the LIM protein FHL2, CBP/p300, and beta-catenin.
abstract: Transcriptional activation of gene expression by Wnt signaling is driven by the association of beta-catenin with TCF/LEF factors and the recruitment of transcriptional coactivators. It has been shown that the LIM protein FHL2 and the acetyltransferase CBP/p300 individually stimulate beta-catenin transactivating activity and that beta-catenin is acetylated by p300. Here, we report that FHL2 and CBP/p300 synergistically enhanced beta-catenin/TCF-mediated transcription from Wnt-responsive promoters and that the acetyltransferase activity of CBP/p300 was involved in the cooperation. CBP/p300 interacted directly with FHL2, predominantly through the CH3 domain but not the histone acetyltransferase domain, and different regions of CBP/p300 were involved in FHL2 and beta-catenin binding. We provided evidence for the formation of a ternary complex by FHL2, CBP/p300, and beta-catenin and for colocalization of the three proteins in the nucleus. In murine FHL2(-/-) embryo fibroblasts, the transactivation activity of beta-catenin/TCF was markedly reduced, and this defect could be restored by exogenous expression of FHL2. However, CBP/p300 were still able to coactivate the beta-catenin/TCF complex in FHL2(-/-) cells, suggesting that FHL2 is dispensable for the coactivator function of CBP/p300 on beta-catenin. Furthermore, we found that FHL2 significantly increased acetylation of beta-catenin by p300 in vivo. Finally, we showed that FHL2, CBP/p300, and beta-catenin could synergistically activate androgen receptor-mediated transcription, indicating that the synergistic coactivator function is not restricted to TCF/LEF.
authors.affiliation: Unité d'Oncogenèse et Virologie Moléculaire, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Labalette
authors.forename: Claire-Angélique
authors.initials: CA
authors.lastname: Renard
authors.forename: Christine
authors.initials: C
authors.lastname: Neuveut
authors.forename: Marie-Annick
authors.initials: MA
authors.lastname: Buendia
authors.forename: Yu
authors.initials: Y
authors.lastname: Wei
mesh_terms: D000107:Acetylation; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D019556:COS Cells; D015820:Cadherins / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology; D004625:Embryo, Nonmammalian; D005347:Fibroblasts / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D018398:Homeodomain Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D060850:LIM-Homeodomain Proteins; D008156:Luciferases / Q000378:metabolism; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D012313:RNA / Q000032:analysis; D011944:Receptors, Androgen / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D018411:Spodoptera / Q000166:cytology; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation; D016335:Zinc Fingers; D051176:beta Catenin
chemical_list: C451405:CITED4 protein, human; C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; C105987:FHL2 protein, human; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D009124:Muscle Proteins; D009363:Neoplasm Proteins; D011944:Receptors, Androgen; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051176:beta Catenin; D012313:RNA; D008156:Luciferases; D005982:Glutathione Transferase