| First Author | Xia Z | Year | 2011 |
| Journal | Proteomics | Volume | 11 |
| Issue | 17 | Pages | 3444-51 |
| PubMed ID | 21751375 | Mgi Jnum | J:177210 |
| Mgi Id | MGI:5294497 | Doi | 10.1002/pmic.201100121 |
| Citation | Xia Z, et al. (2011) Functional analysis of novel phosphorylation sites of CREB-binding protein using mass spectrometry and mammalian two-hybrid assays. Proteomics 11(17):3444-51 |
| abstractText | In the Wnt/beta-catenin pathway, p300/CBP (CREB-binding protein) is recruited by nuclear beta-catenin to regulate a wide array of T-cell factor (TCF)-dependent gene expression. Previous studies have indicated that CBP/beta-catenin complex-mediated transcription is critical for cell proliferation. Both CBP and beta-catenin are phosphoproteins. The interaction domain has been mapped to the N-terminal region of CBP (amino acids 1-111) and the C-terminal region of beta-catenin, but it is unclear whether phosphorylation on specific residues of these regions is required for the interaction. To address this unmet challenge, phosphoproteomic profile of the critical N-terminus of CBP was determined by utilizing TiO(2) affinity chromatography followed by LC-MS/MS analysis. Two unique and novel phosphorylation sites Ser77 and Ser92 were identified. Further studies aided by site-directed mutagenesis, immunoprecipitation and mammalian two-hybrid assay have concluded that the phosphorylation of a Proline-directed Ser92 residue modulates the selective binding ability of CBP with beta-catenin. The specific Mitogen-activated protein kinase inhibitor PD98059, which promotes cell cycle G1 arrest, concomitantly inhibits the interaction, and the evidences suggest that the MEK/ERK (extracellular signal-regulated kinase) cascade activation is the upstream signal required for Ser92 phosphorylation, leading to enhancement of the interaction of CBP with beta-catenin. |
