Genomic structure, chromosome mapping and expression analysis of the human AXIN2 gene.

Conductin is a Wnt signalling protein and serves as a negative regulator of beta-catenin stability. We have previously isolated the human homolog (AXIN2) of the murine conductin gene and shown that it is mutated in colorectal cancer (CRC) with defective mismatch repair (MMR). Here we report the detailed genomic structure of this gene by analysis of cDNA and genomic clones. The gene spans > or =25 kb containing ten exons ranging from 96 bp to 904 bp. All splice donor and acceptor sites conform to the GT/AG rule. FISH (Fluorescence in situ Hybridization) analysis localized this gene to human chromosome band 17q24 and showed that it exists as a single copy in the human genome. Northern blot analysis from different human organs demonstrated that the AXIN2 gene is highly expressed in human thymus, prostate, testis, small intestine and ovarian tissues but expressed at a lower level in colon. The data reported here provides a framework for further analysis of this important Wnt signalling protein in vertebrate development and tumorigenesis.