title: Differentiation of pluripotent C3H10T1/2 cells rapidly elevates CYP1B1 through a novel process that overcomes a loss of Ah Receptor.
abstract: Stimulation of C3H10T1/2 cells by an adipogenic hormonal mixture (IDM) consisting of insulin (I), dexamethasone (D), and methylisobutylxanthine (M) substantially induces cytochrome P450 (CYP) 1B1 expression. This stimulation represents up to 40% of the level produced by maximum activation of the arylhydrocarbon receptor (AhR) with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Dexamethasone and methylisobutylxanthine in combination produced near maximum elevation of CYP1B1 along with a subsequent decline in AhR that paralleled the rise in peroxisome proliferator-activated receptorgamma1 (PPARgamma1). Inhibitors of AhR activity, which block TCDD induction, did not affect this increase of CYP1B1 expression, which was, therefore, independent of AhR activity. These responses were unaffected by inhibition of DNA synthesis, which was required for PPARgamma1 induction and terminal differentiation. Induction of CYP1B1 mRNA was paralleled by increased CYP1B1 promoter-luciferase reporter activity. The initial 0.8kb of promoter region, which was sufficient for 24h near maximum stimulation, did not contain either the key AhR-responsive elements that mediate the TCDD response or CREB and SF1 elements that mediate cAMP stimulation of rat CYP1B1 in steroidogenic cells. This reporter response to IDM stimulation, but not to TCDD, was maintained in AhR-null fibroblasts. CYP1B1 expression, unlike TCDD induction, was stimulated by IDM in only about half the cells. CYP1B1 expression partially overlapped with PPARgamma expression, which was also inversely related in clonal sub-lines. CYP1B1 expression may, therefore, represent an early stage of differentiation that requires factors associated with DNA synthesis to subsequently generate PPARgamma1.
authors.affiliation: Department of Pharmacology and Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, 53706, USA.
authors.forename: Young C
authors.initials: YC
authors.lastname: Cho
authors.forename: Wenchao
authors.initials: W
authors.lastname: Zheng
authors.forename: Megumi
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Xiequing
authors.initials: X
authors.lastname: Liu
authors.forename: Paul R
authors.initials: PR
authors.lastname: Hanlon
authors.forename: Colin R
authors.initials: CR
authors.lastname: Jefcoate
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000187:drug effects / Q000378:metabolism*; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000187:drug effects / Q000378:metabolism; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000187:drug effects / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000187:drug effects / Q000378:metabolism; D065633:Cytochrome P-450 CYP1B1; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D004357:Drug Synergism; D005347:Fibroblasts / Q000187:drug effects; D051379:Mice; D047495:PPAR gamma / Q000187:drug effects / Q000378:metabolism; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D018336:Receptors, Aryl Hydrocarbon / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D020218:Response Elements / Q000187:drug effects; D014157:Transcription Factors / Q000187:drug effects / Q000378:metabolism
chemical_list: C497397:Arnt protein, mouse; D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D047495:PPAR gamma; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D003907:Dexamethasone; D004247:DNA; D001189:Aryl Hydrocarbon Hydroxylases; C585498:Cyp1b1 protein, mouse; C585499:Cyp1b1 protein, rat; D065633:Cytochrome P-450 CYP1B1; D015056:1-Methyl-3-isobutylxanthine