XTcf-3 transcription factor mediates beta-catenin-induced axis formation in Xenopus embryos.
XTcf-3 is a maternally expressed Xenopus homolog of the mammalian HMG box factors Tcf-1 and Lef-1. The N-terminus of XTcf-3 binds to beta-catenin. Microinjection of XTcf-3 mRNA in embryos results in nuclear translocation of beta-catenin. The beta-catenin-XTcf-3 complex activates transcription in a transient reporter gene assay, while XTcf-3 by itself is silent. N-terminal deletion of XTcf-3 (delta N) abrogates the interaction with beta-catenin, as well as the consequent transcription activation. This dominant-negative delta N mutant suppresses the induction of axis duplication by microinjected beta-catenin. It also suppresses endogenous axis specification upon injection into the dorsal blastomeres of a 4-cell-stage embryo. We propose that signaling by beta-catenin involves complex formation with XTcf-3, followed by nuclear translocation and activation of specific XTcf-3 target genes.
Molenaar
M
M
Department of Immunology University Hospital, Utrecht The Netherlands.
van de Wetering
M
M
Oosterwegel
M
M
Peterson-Maduro
J
J
Godsave
S
S
Korinek
V
V
Roose
J
J
Destrée
O
O
Clevers
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003598:Cytoskeletal Proteins / Q000502:physiology*; D018076:DNA, Complementary; D004627:Embryonic Induction; D018507:Gene Expression Regulation, Developmental; D024002:HMGB Proteins; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D015183:Restriction Mapping; D051820:TCF Transcription Factors; D015534:Trans-Activators; D058127:Transcription Factor 3; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014981:Xenopus; D029867:Xenopus Proteins; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D024002:HMGB Proteins; D051820:TCF Transcription Factors; C544917:Tcf3 protein, Xenopus; D015534:Trans-Activators; D058127:Transcription Factor 3; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; D029867:Xenopus Proteins; D051176:beta Catenin