Chibby (CBY1) is a conserved 126 amino acid protein that acts as an antagonist to the canonical WNT signaling pathway. CBY1 binds to the C-terminal region of beta-catenin and inhibits beta-catenin-dependent signaling by competing for the TCF/LEF binding sites and by promoting beta-catenin nuclear export (Takemaru et al, 2003; Li et al, 2008; Li et al, 2010). Endogenous CBY1 and beta-catenin co-immunoprecipitate from HEK293 cells and overexpression of CBY1 reduces expression of a beta-catenin dependent reporter gene, supporting a functional role for the CBY1-beta-catenin interaction in vivo (Takemaru et al, 2003). Studies with CBY1 knockout mice show only a slight effect on expression of WNT-dependent target genes, however; more work will be required to fully elucidate the role of CBY1 in regulating endogenous WNT signaling (Veronina et al, 2009).
Yamaguchi, S, Zhang, Y, Moon, RT, Takemaru, K, Lee, YS, Carthew, RW
Adams, A, Hajjar, AM, Voronina, VA, Takemaru, K, Li, FQ, Treuting, P, Moon, RT, Grubb, BR, Love, D
Mofunanya, A, Harris, K, Takemaru, K, Li, FQ
Hall, J, Mofunanya, A, Fischer, V, Takemaru, K, Li, FQ
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