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Development June 1, 1999; 126 (14): 3159-70.

XCtBP is a XTcf-3 co-repressor with roles throughout Xenopus development.

Brannon M , Brown JD , Bates R , Kimelman D , Moon RT .

XTcf-3 is an HMG box transcription factor that mediates Xenopus dorsal-ventral axis formation. As a Wnt pathway effector, XTcf-3 interacts with beta-catenin and activates the expression of the dorsal organizing gene siamois, while in the absence of beta-catenin, XTcf-3 functions as a transcriptional repressor. We show that XTcf-3 contains amino- and carboxy-terminal repressor domains and have identified a Xenopus member of the C-terminal Binding Protein family of transcriptional co-repressors (XCtBP) as the C-terminal co-repressor. We show that two XCtBP binding sites near the XTcf-3 carboxy-terminus are required for the interaction of XTcf-3 and XCtBP and for the transcriptional repression mediated by the XTcf-3 carboxy-terminal domain. By fusing the GAL4 activation domain to XCtBP we have generated an antimorphic protein, XCtBP/G4A, that activates siamois transcription through an interaction with endogenous XTcf-3. Ectopic expression of XCtBP/G4A demonstrates that XCtBP functions in the regulation of head and notochord development. Our data support a role for XCtBP as a co-repressor throughout Xenopus development and indicate that XCtBP/G4A will be a useful tool in determining how XCtBP functions in various developmental processes.

PubMed ID: 10375506
Article link: Development
Grant support: [+]

Species referenced: Xenopus
Genes referenced: ctbp1 ctbp2 ctnnb1 gdf1 h4c4 lef1 lgals4.2 mmut nodal3.1 nodal3.2 not sia1 tcf4 tcf7l1 wnt8a

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