Title: Transient expression of CYP1A1 in rat epithelial cells cultured in suspension.

Authors: Monk, S A; Denison, M S; Rice, R H

Published In Arch Biochem Biophys, (2001 Sep 1)

Abstract: Suspension of human epidermal cells in methylcellulose-containing medium induces CYP1A1 by a mechanism requiring functional Ah receptor (AhR). In present work CYP1A1 mRNA was induced in a variety of cultured rat epithelial cells by suspension, but the induction was transient, with CYP1A1 mRNA reaching maximal levels by 5 h and disappearing by 12 h. Though the methylcellulose itself contained no detectable ligand, (a) suspension activated the AhR, as judged by mobility shift assays, (b) the AhR competitive inhibitor alpha-naphthoflavone inhibited suspension-mediated induction, and (c) induction was dependent upon dioxin responsive transcriptional elements in the CYP1A1 promoter. The rapid disappearance of CYP1A1 mRNA after 5 h of suspension was unaffected by the addition of TCDD but was prevented by the inclusion of the protein synthesis inhibitor cycloheximide. Thus the downregulation appears to be mediated by a novel short-lived protein induced or activated by suspension.

PubMed ID: 11516172

MeSH Terms: Animals; Base Sequence; Cells, Cultured; Culture Media; Cycloheximide/pharmacology; Cytochrome P-450 CYP1A1/genetics*; DNA Primers/genetics; Gene Expression/drug effects; Genes, Reporter; Keratinocytes/drug effects; Keratinocytes/metabolism; Methylcellulose; Promoter Regions, Genetic; Protein Synthesis Inhibitors/pharmacology; RNA, Messenger/genetics; RNA, Messenger/metabolism; Rats; Receptors, Aryl Hydrocarbon/antagonists & inhibitors; Receptors, Aryl Hydrocarbon/metabolism; Tetrachlorodibenzodioxin/pharmacology