Competitive regulation of human intestinal β-Carotene 15,15’-monooxygenase 1 (BCMO1) gene expression by hepatocyte nuclear factor (HNF)-1α and HNF-4α

Publication date: Available online 30 October 2014 Source:Life Sciences Author(s): Noriaki Yamaguchi , Akiko Sunto , Toshinao Goda , Kazuhito Suruga Aim Among the pro-vitamin A carotenoids, β-carotene is an excellent source of vitamin A. β-Carotene 15,15’-monooxygenase 1 (BCMO1) is a critical enzyme involved in the conversion of β-carotene into vitamin A (retinal) in the small intestine of many vertebrates. In the present study, we investigated the regulation of human BCMO1 gene expression using human intestinal Caco-2 BBe cells. Main methods We performed electrophoretic mobility shift assays and chromatin immunoprecipitation assays to investigate the binding properties of hepatocyte nuclear factor (HNF)-1α and HNF-4α to the proximal promoter of the human BCMO1 gene. Caco-2 BBe cells were also transfected with HNF-1α and HNF-4α siRNAs, and BCMO1 gene expression levels and promoter activity were analyzed by real-time reverse transcription-polymerase chain reaction and luciferase reporter assays, respectively. Key findings We identified overlapping binding sites for HNF-1α and HNF-4α in the human BCMO1 gene proximal promoter. Endogenous nuclear HNF-1α and HNF-4α proteins competitively bound these sites in Caco-2 BBe cells. BCMO1 gene expression levels and promoter activity were significantly decreased in HNF-1α siRNA-transfected Caco-2 BBe cells. In contrast, HNF-4α siRNA-transfected cells exhibited a significant increase in BCMO1 gene expression and ...

Source: Life Sciences - November 4, 2014 Category: Biology Source Type: research