FIG 9.

Schematic of β-catenin-dependent transcription. (A) In the absence of Wnt, β-catenin is degraded in the cytoplasm. Consequently, TCF family members are bound to transcriptional repressors (denoted X) and β-catenin-dependent transcription is silenced. (B) Following Wnt binding to its receptor(s), β-catenin (β-cat) enters the nucleus, binds to TCF family members, displaces transcriptional repressors, and recruits transcriptional coactivators, for example, HMGA1 (denoted Y), which culminates in the stimulation of β-catenin-dependent transcription. (C) ORF2, by virtue of its ability to interact with HMGA1 and β-catenin, stabilizes β-catenin in the nucleus. These interactions lead to enhancement of the coactivator (denoted Y); HMGA1 and CBP, for example, mediated stimulation of β-catenin-dependent transcription. The ability of ORF2 to preferentially interact with single-stranded DNA may be important for these activities.