COLON CARBONIC-ANHYDRASE-1 - TRANSACTIVATION OF GENE-EXPRESSION BY THE HOMEODOMAIN PROTEIN CDX2

The homeodomain protein, Cdx2, has been implicated in the transcriptio nal regulation of genes expressed in the small intestine. In vitro stu dies of the carbonic anhydrase 1 (CA1) colon promoter implied that Cdx 2 may also play a role in the regulation of colon-specific gene expres sion. The current work follows up this proposal by examining the abili ty of Cdx2 to transactivate gene expression in cultured cells mediated by CA1 promoter sequences. The results show that Cdx2 exerts a positi ve regulatory effect by binding to a motif 87 bp upstream of the CA1 T ATA box; this motif appears to act as an enhancer since gene activatio n is independent of its orientation. (C) 1998 Federation of European B iochemical Societies.