Genomic structure of the mouse trefoil factor (Tff) gene cluster in 17q

Introduction In vertebrates, trefoil factor (TFF) domain peptides constitute a class of peptides secreted by the mucous epithelia of the gastrointestinal tract. These peptides promote healing and protection in the gastrointestinal tract. Since the three known human genes are clustered in 21q22.3, a similar arrangement in a paralogous region was possible in mice. The murine intestinal trefoil factor is encoded by the gene Tff3 and was mapped to murine chromosome 17.

Materials and methods Three bacterial and one yeast artificial chromosome recombinants (BAC and YAC) were identified and used for characterisation by PCR, restriction mapping, hybridisation, and fluorescence in situ hybridisation (FISH).

Results and discussion Here we have characterised the genomic structure of all three mouse Tff genes starting with a contig formed by one YAC and three BACs. In a similar fashion to the TFF gene cluster in humans, the Tff genes cover a region of approx. 40 kb in the transcriptional order Tff1–Tff2–Tff3 and localised on mouse chromosome 17. Based on this conserved genomic structure, we propose a model of how mammalian TFF genes may have evolved by exon duplication and unequal crossing over.