Xenobiotic receptors are traditionally defined as xenobiotic chemical-sensing receptors,the activation of which transcriptionally regulates the expression of enzymes and transporters involved in the metabolism and dis...Xenobiotic receptors are traditionally defined as xenobiotic chemical-sensing receptors,the activation of which transcriptionally regulates the expression of enzymes and transporters involved in the metabolism and disposition of xenobiotics.Emerging evidence suggests that“xenobiotic receptors”also have diverse endobiotic functions,including their effects on lipid metabolism and energy metabolism.Dyslipidemia is a major risk factor for cardiovascular disease,diabetes,obesity,metabolic syndrome,stroke,nonalcoholic fatty liver disease(NAFLD),and nonalcoholic steatohepatitis(NASH).Understanding the molecular mechanism by which transcriptional factors,including the xenobiotic receptors,regulate lipid homeostasis will help to develop preventive and therapeutic approaches.This review describes recent advances in our understanding the atypical roles of three xenobiotic receptors:aryl hydrocarbon receptor(AhR),pregnane X receptor(PXR),and constitutive androstane receptor(CAR),in metabolic disorders,with a particular focus on their effects on lipid and glucose metabolism.Collectively,the literatures suggest the potential values of AhR,PXR and CAR as therapeutic targets for the treatment of NAFLD,NASH,obesity and diabetes,and cardiovascular diseases.展开更多
Pregnane and Xenobiotic Receptor (PXR; or Steroid and Xenobiotic Receptor, SXR), a new member of the nuclear receptor superfamily, is thought to modulate a network of genes that are involved in xenobiotic metabolism a...Pregnane and Xenobiotic Receptor (PXR; or Steroid and Xenobiotic Receptor, SXR), a new member of the nuclear receptor superfamily, is thought to modulate a network of genes that are involved in xenobiotic metabolism and elimination. To further explore the role of PXR in body’s homeostatic mechanisms, we for the first time, report successful prokary- otic expression and purification of full-length PXR and preparation of polyclonal antibody against the whole protein. The full-length cDNA encoding a 434 amino acids protein was sub-cloned into prokaryotic expression vector, pET-30b and transformed into E. coli BL21(DE3) cells for efficient over expression. The inclusion body fraction, containing the expressed recombinant protein, was purified first by solubilizing in sarcosine extraction buffer and then by affinity column chromatography using Ni-NTA His-Bind matrix. The efficacy of anti-PXR antibody was confirmed by immunocytology, Western blot analysis, EMSA and immunohistochemistry. The antibody obtained was capable of detecting human and mouse PXR with high specificity and sensitivity. Immunofluorescence staining of COS-1 cells transfected with human or mouse PXR showed a clear nuclear localization. Results from immunohistochemistry showed that level of PXR in liver sections is immunologically detectable in the nuclei. Similar to exogenously transfected PXR, Western blot analysis of cell extract from HepG2 and COLO320DM cells revealed a major protein band for endogenous PXR having the expected molecular weight of 50 kDa. Relevance of other immunodetectable bands with reference to PXR isoforms and current testimony are evaluated. Advantages of antibody raised against full-length PXR protein for functional characterization of receptor is discussed and its application for clinical purposes is envisaged.展开更多
基金supported in part by National Institutes of Health grants DK083952,HD073070,DK099232,ES023438,,ES030429(to W.X.)WX is also supported in part by the Joseph Endowed Professorship from the University of Pittsburgh School of Pharmacy.
文摘Xenobiotic receptors are traditionally defined as xenobiotic chemical-sensing receptors,the activation of which transcriptionally regulates the expression of enzymes and transporters involved in the metabolism and disposition of xenobiotics.Emerging evidence suggests that“xenobiotic receptors”also have diverse endobiotic functions,including their effects on lipid metabolism and energy metabolism.Dyslipidemia is a major risk factor for cardiovascular disease,diabetes,obesity,metabolic syndrome,stroke,nonalcoholic fatty liver disease(NAFLD),and nonalcoholic steatohepatitis(NASH).Understanding the molecular mechanism by which transcriptional factors,including the xenobiotic receptors,regulate lipid homeostasis will help to develop preventive and therapeutic approaches.This review describes recent advances in our understanding the atypical roles of three xenobiotic receptors:aryl hydrocarbon receptor(AhR),pregnane X receptor(PXR),and constitutive androstane receptor(CAR),in metabolic disorders,with a particular focus on their effects on lipid and glucose metabolism.Collectively,the literatures suggest the potential values of AhR,PXR and CAR as therapeutic targets for the treatment of NAFLD,NASH,obesity and diabetes,and cardiovascular diseases.
文摘Pregnane and Xenobiotic Receptor (PXR; or Steroid and Xenobiotic Receptor, SXR), a new member of the nuclear receptor superfamily, is thought to modulate a network of genes that are involved in xenobiotic metabolism and elimination. To further explore the role of PXR in body’s homeostatic mechanisms, we for the first time, report successful prokary- otic expression and purification of full-length PXR and preparation of polyclonal antibody against the whole protein. The full-length cDNA encoding a 434 amino acids protein was sub-cloned into prokaryotic expression vector, pET-30b and transformed into E. coli BL21(DE3) cells for efficient over expression. The inclusion body fraction, containing the expressed recombinant protein, was purified first by solubilizing in sarcosine extraction buffer and then by affinity column chromatography using Ni-NTA His-Bind matrix. The efficacy of anti-PXR antibody was confirmed by immunocytology, Western blot analysis, EMSA and immunohistochemistry. The antibody obtained was capable of detecting human and mouse PXR with high specificity and sensitivity. Immunofluorescence staining of COS-1 cells transfected with human or mouse PXR showed a clear nuclear localization. Results from immunohistochemistry showed that level of PXR in liver sections is immunologically detectable in the nuclei. Similar to exogenously transfected PXR, Western blot analysis of cell extract from HepG2 and COLO320DM cells revealed a major protein band for endogenous PXR having the expected molecular weight of 50 kDa. Relevance of other immunodetectable bands with reference to PXR isoforms and current testimony are evaluated. Advantages of antibody raised against full-length PXR protein for functional characterization of receptor is discussed and its application for clinical purposes is envisaged.