AbstractsBiology & Animal Science

Background: Inflammatory bowel disease (IBD) is known to reduce expression of the gene caudal type homeobox transcription factor 2 (CDX2). CDX2 has a critical role in differentiation of intestinal epithelial cells (IEC), as well as in regulating several intestinal specific genes, including meprin 1A (MEP1A). Recent studies have indicated the existence of a previously unidentified isoform of CDX2, expressed from an alternative, CUG start codon, termed variant-CDX2 (vCDX2). Furthermore vCDX2 mRNA has been shown to be highly expressed in IECs of IBD patients. Aim: This study investigates whether vCDX2 give rise to a protein and the nature vCDX2 as a transcriptional factor, in relation to CDX2’s effect on the MEP1A-promotor. Methods: Translation of vCDX2 was enhanced by changing the start codon from CUG to AUG using site directed mutagenesis. A western blot was used to determine the translation of vCDX2. A dual luminescence reporter gene assay was used to quantify the effect of vCDX2 and CDX2 on the activity of the MEP1A-promoter. Results: The western blot confirmed that vCDX2 is translated into a protein. The reporter assay showed that the effect of CDX2 on the expression of MEP1A was significantly reduced when vCDX2 was present. Conclusions: vCDX2 is translated into a protein. vCDX2 has a dominant negative effect on CDX2 as a transcriptional factor on the MEP1A-promotor.