β-oxidation of long and very long chain fatty acyl-CoA derivatives occurs in peroxisomes, which are ubiquitous subcellular organelles of eukaryotic cells. This pathway releases acetyl-CoA as precursor for several key molecules such as cholesterol. Numerous enzymes participating to cholesterol and fatty acids biosynthesis pathways are co-localized in peroxisomes and some of their encoding genes are known as targets of the NFY transcriptional regulator. However, until now no interaction between NFY transcription factor and genes encoding peroxisomal β-oxidation has been reported. This work studied the interactions between NFY factor with the rat gene promoters of two enzymes of the fatty acid β-oxidation, MFP-1 (multifunctional protein type 1) and ThB (thiolase B) and their involvement in the cholesterol dependent-gene regulation. Binding of this nuclear factor to the ATTGG motif of the MFP-1 and of the ThB promoters was demonstrated by EMSA (Electrophoretic Mobility Shift Assay) and super shift assay. In contrast, in spite of the presence of putative Sp1 binding sites in these promoters, competitive EMSA did not reveal any binding. The promoter-dependent luciferase gene expression was downregulated by cholesterol in MFP-1 and ThB promoters harbouring constructs. This work describes for the first time a NFY interaction with promoter sequences of the peroxisomal β-oxidation encoding genes. It suggests that cholesterol would negatively regulate the expression of genes involved in β-oxidation, which generates the initial precursor for its own biosynthesis, via at least the NFY transcription factor.
