Peroxisome proliferator-activated receptor gamma is induced during differentiation of colon epithelium cells

Peroxisome proliferator-activated receptor gamma (PPAR gamma), a fatty acid-activated nuclear receptor, is implicated in adipocyte differentiation and insulin sensitisation. In view of the association of dietary fat intake and bowel disease, the expression of PPAR gamma in rodent and human intestine was studied. Expression of PPAR gamma mRNA was examined by Northern blot hybridisation, RNase protection, and/or competitive RT-PCR assays, whereas PPAR gamma protein levels were evaluated by immunoblotting and immunohistochemistry. PPAR gamma mRNA and protein were abundantly expressed in colon relative to the small intestine both in rodents and in man. Interestingly, expression of PPAR gamma was primarily localised in the more differentiated epithelial cells in the colon. The level of expression of PPAR gamma in colon was similar to the levels seen in adipose tissue. Expression of PPAR gamma increased from proximal to distal segments of the colon in man. In Caco-2 and HT-29 human adenocarcinoma cells, PPAR gamma expression increased upon differentiation, consistent with PPAR gamma being associated with a differentiated epithelial phenotype. High-level expression of PPAR gamma was observed in the colon, but not in the small intestine, suggesting a potential role of this nuclear receptor in the colon.