Molecular and dietary regulation of beta,beta-carotene 15,15'-monooxygenase 1 (BCMO1).

beta,beta-Carotene 15,15'-monooxygenase-1 (BCMO1) is a key enzyme in vitamin A metabolism in mammals. Various dietary components such as non-pro-vitamin A carotenoids, fat, and polyphenols have been shown to influence the intestinal absorption and conversion of pro-vitamin A carotenoids. Furthermore, vitamin A deficiency has been shown to induce BCMO1 expression, whereas supplementation with vitamin A or its active metabolites, all-trans and 9-cis retinoic acid, dose-dependently reverse these effects. A diet-responsive regulatory network involving the intestine specific homeodomain transcription factor ISX has been shown to regulate the intestinal vitamin A uptake and production via a negative feedback control. Furthermore, non-synonymous single nucleotide polymorphisms in the human BCMO1 gene have been discovered causing observably reduced BCMO1 activity. Detailed knowledge about BCMO1 regulation as well as genetic variations causing variable cleavage activities may provide a background, on which individual and/or population based dietary recommendations for beta-carotene and vitamin A intake could be established.