TY  - JOUR
A1  - Rühl, Ralph
A1  - Sczech, Ronny
A1  - Landes, Nico
A1  - Pfluger, Paul Thomas
A1  - Kluth, Dirk
A1  - Schweigert, Florian J.
T1  - Carotenoids and their metabolites are naturally occurring activators of gene expression via the pregnane X receptor
N2  - Carotenoids are important micronutrients in the human diet and are present in human serum at micromolar concentrations. In addition to their antioxidant potential, carotenoids obtain physiologically relevant properties such as influencing cellular signal pathways, gene expression or induction of detoxifying enzymes. In this study, we determined the transactivation of PXR by cotransfection with the full-length receptor and a PXR-responsive reporter gene. Carotenoids and retinol revealed a 5-6-fold reporter gene activity in HepG2 cells in comparison to a 7-fold induction by the well known PXR agonist rifampicin whereas apo-carotenals and lycopene exerted less or no activation potential. The inductive efficacy was hereby concentration-dependent. In addition, carotenoid or retinol mediated gene expression of PXR responsive genes like CYP3A4/CYP3A7, CYP3A5, MDR-1 and MRP-2 has been determined in HepG2 cells by RT- PCR with upregulative properties of beta-carotene or retinol being comparable or even higher than that of rifampicin. In conclusion, PXR-mediated upregulation of CYP3A4/CYP3A7 and CYP3A5 as well as MDR1 and MRP2 by carotenoids points to a potential interference on the metabolism of xenobiotic and endogenous relevant compounds
Y1  - 2004
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/15309
ER  -