Cell
Volume 88, Issue 6, 21 March 1997, Pages 789-799
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Article
Armadillo Coactivates Transcription Driven by the Product of the Drosophila Segment Polarity Gene dTCF

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Abstract

The vertebrate transcription factors TCF (T cell factor) and LEF (lymphocyte enhancer binding factor) interact with β-catenin and are hypothesized to mediate Wingless/Wnt signaling. We have cloned a maternally expressed Drosophila TCF family member, dTCF. dTCF binds a canonical TCF DNA motif and interacts with the β-catenin homolog Armadillo. Previous studies have identified two regions in Armadillo required for Wingless signaling. One of these interacts with dTCF, while the other constitutes a transactivation domain. Mutations in dTCF and expression of a dominant-negative dTCF transgene cause a segment polarity phenotype and affect expression of the Wingless target genes engrailed and Ultrabithorax. Epistasis analysis positions dTCF downstream of armadillo. The Armadillo–dTCF complex mediates Wingless signaling as a bipartite transcription factor.

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