Expression and induction by rifampicin of CAR- and PXR-regulated CYP2B and CYP3A in liver, kidney and airways of pig

Toxicology. 2008 Oct 30;252(1-3):105-12. doi: 10.1016/j.tox.2008.08.004. Epub 2008 Aug 22.

Abstract

The transcript levels of CYP2B22, 3A22, 3A29, 3A46, CAR, PXR and HNF4alpha were investigated in liver, kidney and airways from control and rifampicin-treated male pigs. The presence and induction of CYP genes transcription were studied by RT-PCR, real-time PCR, Western blotting and enzymatic activity whereas the expression of receptors was studied by RT-PCR or real-time PCR. Pretreatment with rifampicin resulted in a transcriptional activation, although to different extents, of all the CYP3A genes in liver but not in kidney, lung, bronchi or trachea. In the hepatic microsomes, the induction of CYP3A genes was accompanied by an increase of CYP3As marker activities and of two protein bands immunoreactive with anti-human CYP3A4. The CYP2B22 transcript was found to be markedly induced only in liver and kidney. In parallel, a protein band immunoreactive with anti-rat CYP2B1 was elevated while enhanced CYP2B marker activities were observed in hepatic and renal microsomes. As expected, based on human data, the basal expression of CAR, PXR and HNF4alpha was found to be high in liver and low in airways and not susceptible to induction by rifampicin. A significant expression of these transcriptional factors was also demonstrated in kidney. Thus, it is likely that rifampicin induced CYP2B22 both in liver and kidney of pig, not via activation of CAR, but via PXR, through a cross-talk mechanism, as previously observed in human liver. Taken together, our results demonstrated a differential expression and regulation of three individual CYP3As, CYP2B22, CAR, PXR and HNF4alpha genes in liver, kidney and airways of pig.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibiotics, Antitubercular / pharmacology*
  • Blotting, Western
  • Cytochrome P-450 CYP2B1 / biosynthesis*
  • Cytochrome P-450 CYP3A / biosynthesis*
  • DNA / biosynthesis
  • DNA / isolation & purification
  • DNA Primers
  • Enzyme Induction / drug effects
  • Hepatocyte Nuclear Factor 4 / biosynthesis
  • Hepatocyte Nuclear Factor 4 / genetics
  • Kidney / drug effects
  • Kidney / enzymology*
  • Liver / drug effects
  • Liver / enzymology*
  • Microsomes / drug effects
  • Microsomes / enzymology
  • Microsomes, Liver / drug effects
  • Microsomes, Liver / enzymology
  • Pregnane X Receptor
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / isolation & purification
  • Receptors, Cytoplasmic and Nuclear / drug effects*
  • Receptors, Steroid / drug effects*
  • Respiratory System / drug effects
  • Respiratory System / enzymology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Rifampin / pharmacology*
  • Swine
  • Transcription Factors / drug effects*

Substances

  • Antibiotics, Antitubercular
  • DNA Primers
  • Hepatocyte Nuclear Factor 4
  • Pregnane X Receptor
  • RNA, Messenger
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Steroid
  • Transcription Factors
  • constitutive androstane receptor
  • DNA
  • Cytochrome P-450 CYP2B1
  • Cytochrome P-450 CYP3A
  • Rifampin