Regional expression of epithelial dipeptidyl peptidase IV in the human intestines

The expression of DPP IV/CD26 was studied in epithelial cells from different regions of the human small intestine and colon. The following data were obtained: 1) DPP IV/CD26 activity was highest in ileum and jejunum, low in duodenum and not detectable in colon; 2) The amount of DPP IV, as analyzed by Western blotting, was very low in duodenum and increased up to the ileum. No DPP IV protein was detected in colon; 3) RT-PCR analysis showed the expected 315-bp product in the small intestine with the highest signal in ileum and jejunum and a low signal in duodenum; a faint PCR signal could be detected in colon. Similar data were obtained by Northern blot analysis which revealed a 3.6-kb transcript only in small intestine. It is concluded that DPP IV/CD26 gene expression in human intestine is highest in the distal small intestine, and that is regulated at the mRNA level.