MOLECULAR REGULATION OF TRANSFERRIN RECEPTOR AND FERRITIN EXPRESSION IN THE RAT GASTROINTESTINAL-TRACT

Background & Aims: The role of the transferrin receptor and ferritin i n the regulation of intestinal dietary iron uptake and excretion is un known. This study aimed to determine the regulation of transferrin rec eptor and ferritin messenger RNA (mRNA) in the rat gastrointestinal tr act in response to dietary iron changes. Methods: In situ hybridizatio n studies for transferrin receptor and L-ferritin mRNAs were performed using tissues from normal, iron-deficient, and iron-loaded rats. Resu lts: L-Ferritin mRNA was localized to small intestinal crypt and villu s epithelial cells and colonic crypt and surface epithelial cells with mRNA levels up-regulated in iron-loaded rats. Transferrin receptor mR NA was detected in crypt epithelial cells of the small and large intes tine in iron-deficient and normal vats. In contrast, in iron-loaded ra ts, transferrin receptor mRNA was also detected in the superficial epi thelial cells of the small intestine and colon, which contained increa sed stores of iron. Transferrin receptor mRNA levels were increased in the colon. Conclusions: In the iron-deficient and normal rat intestin e, transferrin receptor mRNA was expressed only by proliferating crypt epithelial cells. In iron-loaded rats, however, surface enterocytes o f the intestine expressed both transferrin receptor mRNA and increased ferritin mRNA levels.