title: Presence of the 4 S polycyclic hydrocarbon-binding protein in H4-II-E cells.
abstract: The 4 S polycyclic aromatic hydrocarbon (PAH)-binding protein had been implicated in regulating the expression of rat cytochrome P450IA1 which is most closely associated with aryl hydrocarbon hydroxylase (AHH). We have now investigated the presence of both the 4 S PAH-binding protein and the 8 S Ah receptor in rat hepatoma H4-II-E cells as well as the induction of P450IA1 upon their exposure to PAH's such as benzo[a]pyrene (BP) and 3-methylcholanthrene (3MC), and halogenated dioxins such as 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD) and 2,3,7,8-tetrachlorodibenzofuran (TCDBF). Sucrose density gradient analyses and hydroxylapatite assays indicate that, in addition to the 8 S protein, the 4 S PAH binding protein is present in these cells. This protein interacts in a saturable and high affinity manner with BP and 3MC, but not with TCDD or TCDBF. Using a P450IA1 probe, the induction of gene expression was observed by Northern blot analysis of total cellular RNA after exposure of the H4-II-E cells to BP, 3MC, or TCDBF. Since the 4 S protein was observed to interact only with BP and 3MC, these results suggest that this protein may also play a role in the PAH-induced expression of cytochrome P450IA1 gene expression in H4-II-E.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68105.
authors.forename: A
authors.initials: A
authors.lastname: Raha
authors.forename: V
authors.initials: V
authors.lastname: Reddy
authors.forename: L C
authors.initials: LC
authors.lastname: Xu
authors.forename: W H
authors.initials: WH
authors.lastname: Houser
authors.forename: E
authors.initials: E
authors.lastname: Bresnick
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002352:Carrier Proteins / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D050938:Glycine N-Methyltransferase; D008114:Liver Neoplasms, Experimental / Q000201:enzymology / Q000378:metabolism*; D008748:Methylcholanthrene / Q000633:toxicity*; D008780:Methyltransferases; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug / Q000187:drug effects* / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D002352:Carrier Proteins; D000072317:Polychlorinated Dibenzodioxins; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug; D001564:Benzo(a)pyrene; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D008780:Methyltransferases; D050938:Glycine N-Methyltransferase