title: NATb/NAT1*4 promotes greater arylamine N-acetyltransferase 1 mediated DNA adducts and mutations than NATa/NAT1*4 following exposure to 4-aminobiphenyl.
abstract: N-acetyltransferase 1 (NAT1) is a phase II metabolic enzyme responsible for the biotransformation of aromatic and heterocyclic amine carcinogens such as 4-aminobiphenyl (ABP). NAT1 catalyzes N-acetylation of arylamines as well as the O-acetylation of N-hydroxylated arylamines. O-acetylation leads to the formation of electrophilic intermediates that result in DNA adducts and mutations. NAT1 is transcribed from a major promoter, NATb, and an alternative promoter, NATa, resulting in mRNAs with distinct 5'-untranslated regions (UTR). NATa mRNA is expressed primarily in the kidney, liver, trachea, and lung while NATb mRNA has been detected in all tissues studied. To determine if differences in 5'-UTR have functional effect upon NAT1 activity and DNA adducts or mutations following exposure to ABP, pcDNA5/FRT plasmid constructs were prepared for transfection of full-length human mRNAs including the 5'-UTR derived from NATa or NATb, the open reading frame, and 888 nucleotides of the 3'-UTR. Following stable transfection of NATb/NAT1*4 or NATa/NAT1*4 into nucleotide excision repair (NER) deficient Chinese hamster ovary cells, N-acetyltransferase activity (in vitro and in situ), mRNA, and protein expression were higher in NATb/NAT1*4 than NATa/NAT1*4 transfected cells (P < 0.05). Consistent with NAT1 expression and activity, ABP-induced DNA adducts and hypoxanthine phosphoribosyl transferase mutants were significantly higher (P < 0.05) in NATb/NAT1*4 than in NATa/NAT1*4 transfected cells following exposure to ABP. These differences observed between NATa and NATb suggest that the 5'-UTRs are differentially regulated.
authors.affiliation: Department of Pharmacology and Toxicology, James Graham Brown Cancer Center and Center for Environmental Genomics and Integrative Biology, University of Louisville, Louisville, Kentucky 40202-1617, USA.
authors.forename: Lori M
authors.initials: LM
authors.lastname: Millner
authors.forename: Mark A
authors.initials: MA
authors.lastname: Doll
authors.forename: Jian
authors.initials: J
authors.lastname: Cai
authors.forename: J Christopher
authors.initials: JC
authors.lastname: States
authors.forename: David W
authors.initials: DW
authors.lastname: Hein
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000107:Acetylation; D017398:Alternative Splicing; D000611:Aminobiphenyl Compounds / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000235:genetics* / Q000378:metabolism; D001711:Biotransformation; D015153:Blotting, Western; D016466:CHO Cells; D019556:COS Cells; D002273:Carcinogens / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D018736:DNA Adducts / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000187:drug effects*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020121:5' Untranslated Regions; D000611:Aminobiphenyl Compounds; D002273:Carcinogens; D018736:DNA Adducts; D007527:Isoenzymes; C006757:4-biphenylamine; D001191:Arylamine N-Acetyltransferase; D007041:Hypoxanthine Phosphoribosyltransferase