title: Gender dictates the nuclear receptor-mediated regulation of CYP3A44.
abstract: The CYP3As are broad-spectrum drug-metabolizing enzymes that are collectively responsible for more than 50% of xenobiotic metabolism. Unlike other CYP3As, murine CYP3A44 is expressed predominantly in the female liver, with much lower levels in male livers and no detectable expression in brain or kidney in either gender. In this study, we examined the role of nuclear hormone receptors in the regulation of Cyp3a44 gene expression. Interestingly, we observed differential effects of pregnane X receptor (PXR) and constitutive androstane receptor (CAR) -mediated activation of Cyp3a44 gene expression, which was gender-specific. For example, activation of PXR by pregnenolone-16alpha-carbonitrile (PCN) and dexamethasone (DEX) induced CYP3A44 mRNA levels in a PXR-dependent fashion in male mice, whereas no induction was detected in female mice. In contrast, PCN and DEX down-regulated CYP3A44 expression in female PXR null animals. Similar to PXR, CAR activation also showed a male-specific induction with no effect on CYP3A44 levels in females. When PXR knockout mice were challenged with the CAR activator phenobarbital, a significant up-regulation of male CYP3A44 levels was observed, whereas levels in females remained unchanged. We conclude that gender has a critical impact on PXR- and CAR-mediated effects of CYP3A44 expression.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical School of Houston, P.O. Box 20708, Houston, TX 77225, USA.
authors.forename: Sayeepriyadarshini
authors.initials: S
authors.lastname: Anakk
authors.forename: Wendong
authors.initials: W
authors.lastname: Huang
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Staudinger
authors.forename: Kheng
authors.initials: K
authors.lastname: Tan
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Cole
authors.forename: David D
authors.initials: DD
authors.lastname: Moore
authors.forename: Henry W
authors.initials: HW
authors.lastname: Strobel
mesh_terms: D000818:Animals; D000090702:Constitutive Androstane Receptor; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D005260:Female; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000077297:Pregnane X Receptor; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011987:Receptors, Steroid / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012737:Sex Factors; D013739:Testosterone / Q000378:metabolism; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins
chemical_list: D000090702:Constitutive Androstane Receptor; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System; D000077297:Pregnane X Receptor; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D013739:Testosterone; D014157:Transcription Factors; C464819:Cyp3a44 protein, mouse; C496508:Cyp3a11 protein, mouse; D008565:Membrane Proteins