CYP3A Inhibition By NAFLD Is Independent Of PXR Pathway

The first part Changes of CYP3A expression and PXR nuclear translocation in NAFLDAims:Non-alcoholic fatty liver disease affects many kinds of drug metabolizing enzymes in the liver,and CYP3A is the principal one of them.Pregnane X receptor(PXR)participates in the regulation of CYP3A transcription.In this experiment,we describe the changes of the expression level of them,which will lay the foundation for further exploration of the possible interconnections between them.Methods and Materials:To estabilish an animal model of hepatic steatosis,seven-to eight-week-old male mice were randomly divided into two groups,feeding standard chow,high fat diet(HFD)for 8 weeks,respectively.The triglyceride content of them was measured.To estabilish an cellular model of hepatic steatosis,HepG2 cells were exposed to a mixture of palmitic acid(PA)for 24 hours.The triglyceride content of them was also measured.The mRNA expression of CYP3A11 in HFD-induced model and the mRNA expression of CYP3A4 in PA-induced model were detected by qRT-PCR and WB,and the nuclear translocation levels of PXR were also detected.Results:The expression of CYP3A11 mRNA and protein are decreased in HFD-induced model of NAFLD,and the expression of CYP3A4 mRNA is also decreased in PA-induced model of NAFLD.The level of PXR nuclear translocation is increased both in cellular and mouse models of NAFLD.Conclusions:The expression of CYP3A is decreased both in cellular and mouse models of NAFLD,but the level of PXR nuclear translocation is increased.The second part The effect of knockdown and over-expressing PXRon transcriptional activity and expression of PXR-CYP3A4 inNAFLD celluar modelAims:It has been reported that the down-regulation of CYP3A in NALFD is exerted by the PXR-FGF21 pathway.This experiment further analyzed the effect of knockdown and over-expression of PXR on the transcriptional activity and expression of PXR-CYP3A4 in cellular model,then to investigate whether the decline in CYP3A expression of NAFLD is related to the PXR pathway or not.Methods and Materials:We used small interfering RNA technology to inhibit the expression of PXR in vitro.The expression of PXR was enhanced by plasmid transfection technique.The expression of PXR and CYP3A4 mRNA were detected by qRT-PCR and WB.The activity of CYP3 A4 promoter transcriptional was detected by luciferase.Results:Whatever knockdown or over-expressing PXR,PA-induced model of NAFLD still inhibited CYP3A4 promoter transcriptional activity and CYP3A4 expression.Conclusions:CYP3A inhibition by NAFLD is independent of PXR pathway.