Induction of a beta-catenin-LEF-1 complex by wnt-1 and transforming mutants of beta-catenin.

Signal transduction by beta-catenin involves its posttranslational stabilization and import to the nucleus where it interacts with transcription factors. Recent implications for beta-catenin signaling in cancer prompted us to examine colon cancer cell lines for the expression of LEF-1, a transcription factor that binds to beta-catenin. The analysis of several ...
cell lines revealed the expression of LEF1 mRNA and a constitutive association of the LEF-1 protein with beta-catenin. In contrast to the colon cells, PC12 and 293 cells did not contain a beta-catenin-LEF-1 complex, even though both proteins were detected in cell lysates. In these cells, the association of endogenous LEF1 and beta-catenin was induced by stimulation with the wnt-1 proto-oncogene. The complex formed following transient stimulation with wnt-1 and also persisted in cells stably expressing wnt-1. Ectopic overexpression of beta-catenin in 293 cells also induced the assembly of the beta-catenin-LEF-1 complex and activated gene transcription from a LEF-1-dependent promotor. Expression of mutant oncogenic forms of beta-catenin identified in cancer cells resulted in higher levels of transcriptional activity. The results suggest that a cancer pathway driven by wnt-1, or mutant forms of beta-catenin, may involve the formation of a persistent transcriptionally active complex of beta-catenin and LEF1.
Mesh Terms:
Animals, Cadherins, Cell Transformation, Neoplastic, Colonic Neoplasms, Cytoskeletal Proteins, DNA-Binding Proteins, Humans, Immunoblotting, Lymphoid Enhancer-Binding Factor 1, Melanoma, Mice, Mutation, PC12 Cells, Precipitin Tests, Proto-Oncogene Proteins, Rats, Signal Transduction, Trans-Activators, Transcription Factors, Tumor Cells, Cultured, Wnt Proteins, Wnt1 Protein, Zebrafish Proteins, beta Catenin
Oncogene
Date: Dec. 04, 1997
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