Papachristodoulou, M: Study of ligand-binding properties of

Hepatocyte nuclear factor 4a (HNF4a) is a liver enriched transcription factor that belongs to the nuclear receptor family, and controls the expression of genes involved in various different functions, such as nutrient transport, metabolism, growth and differentiation. Recently, fatty acids and/or fatty acyl CoAs as well as some xenobiotics (e.g. hypolipidemic drugs) have been suggested as HNF4a ligands. The aim of this study was to identify potential ligands for HNF4a, using a DAUDA fluorescence displacement assay. LFABP was expressed and purified as a positive control, and used successfully to validate the DAUDA assay. Rat HNF4aLBD was successfully expressed and purified, therefore further work for ligand identification was performed using the rat HNF4a. Suitability of the DAUDA fluorescence displacement assay for screening of ligands for rat HNF4a was confirmed by a characteristic blue shift in fluorescence emission upon protein binding, as previously reported. Ligands screened in this study included five different fatty acids, palmitoyl CoA, and hypolipidemic xenobiotics of the fibrate family (fenofibrate, bezafibrate, clofibrate), as well as pioglitazone (a thionolidinedione).