CAR expression and inducibility of CYP2B genes in liver of rats treated with PB-like inducers.
The expression of the CAR gene and inducibility of CYP2B protein in the liver of male Wistar rats treated with phenobarbital (PB) and triphenyldioxane (TPD) were investigated. To clarify the role of phosphorylation/dephosphorylation in these processes, rats were treated with inhibitors of Ca(2+)/calmodulin-dependent kinase II (W7) or protein phosphatases PP1 and PP2A (OA) before induction. Constitutive expression of the CAR gene in livers of untreated rats was detected by multiplex RT-PCR. Treatment with W7 resulted in a 2.8-fold induction of CAR gene expression, whereas OA led to a 2.4-fold decrease of the mRNA level. The same results were obtained for CYP2B genes expression, which were increased by W7 treatment (two-fold) and decreased by OA (2.3-fold). PB-induction did not lead to significant alteration in the level of CAR gene expression, although CYP2B genes expression was enhanced two-fold over control values. TPD caused a two-fold increase of both CAR and CYP2B mRNA levels. Both inducers reduced the effects of inhibitors on CAR gene expression. Results of EMSA showed that PB, TPD or W7 alone induced formation of complexes of NR1 with nuclear proteins. Appearance of the complexes correlated with an increase in CYP2B expression, and their intensities were modulated by the protein kinase inhibitors. Thus, our results demonstrate that constitutive expressions of CAR as well as CYP2B during induction are regulated by phosphorylation/dephosphorylation processes.
Pustylnyak
Vladimir O
VO
Institute of Molecular Biology and Biophysics, Timakova str. 2, Novosibirsk 630117, Russia. pustylnyak@ngs.ru
Gulyaeva
Lyudmila F
LF
Lyakhovich
Vyacheslav V
VV
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D000090702:Constitutive Androstane Receptor; D019362:Cytochrome P-450 CYP2B1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics*; D018076:DNA, Complementary / Q000096:biosynthesis; D004146:Dioxanes / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D020536:Enzyme Activators / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013449:Sulfonamides / Q000494:pharmacology; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*
D000090702:Constitutive Androstane Receptor; D065607:Cytochrome P-450 Enzyme Inhibitors; D018076:DNA, Complementary; D004146:Dioxanes; D020536:Enzyme Activators; D009687:Nuclear Proteins; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D013449:Sulfonamides; D014157:Transcription Factors; C054589:2,4,6-triphenyl-1,3-dioxane; C017967:W 7; D003577:Cytochrome P-450 Enzyme System; D019362:Cytochrome P-450 CYP2B1; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010634:Phenobarbital