Date of Award
Master of Science
Food Science and Human Nutrition
Wendy S. White
Iron is an essential cofactor of beta-carotene 15, 15'-monooxygenase (BCMO) which catalyzes the formation of vitamin A from beta-carotene. In addition to being a cofactor, iron may play a role in the regulation of BCMO. In the present study, we investigated the effects of iron on the gene expression and enzyme activity of BCMO in the cultured TC7 clone of Caco-2 human intestinal cells, a human in vitro model. Cells on day 15 post-confluency were treated with ferrous sulfate (FeSO4) at 0, 0.01 or 0.5 mM for 2, 4, 6 or 12 h for analysis of mRNA expression, or 2, 3, 4, 6, 24, or 48 h for determination of enzymatic activity. The results showed that compared with the 0 mM FeSO4 controls, higher dose iron (0.5 mM) significantly increased BCMO mRNA expression in a time-dependent manner during 12 h of treatment with peak mRNA expression at 2 h (2.3-fold increase). The 0.01 mM FeSO4 treatment enhanced BCMO mRNA expression at 2 h and 4 h incubation with iron. However, this lower concentration of FeSO4 had a lesser effect in stimulating BCMO mRNA expression than 0.5 mM FeSO4, suggesting a dose-dependent enhancing effect of iron. Despite the increased mRNA expression, BCMO enzyme activities were not increased by 0.5 mM FeSO4 treatment at any of the observed time points (2-48 h). These data suggest that iron up-regulates BCMO mRNA levels but not its catalytic activity under our cell culture conditions.
Wang, Zhenguo, "Iron dependency of beta-carotene 15, 15'-monooxygenase in Caco-2 TC7 cells" (2008). Graduate Theses and Dissertations. 11800.