Abstract
Human N-acetyltransferase 2 (NAT2) genetic polymorphism is associated with drug toxicity and/or carcinogenesis in various tissues. Knowledge of NAT2 gene structure and expression is critical for understanding these associations. Previous findings suggest that human NAT2 expression is highest in liver and gut but expressed at functional levels in other tissues. A sensitive and specific TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR) assay with intron-spanning primers was developed and used, together with a second TaqMan RT-PCR assay based on amplification of a NAT2 open reading frame (ORF) exon segment, to measure NAT2 mRNA in 29 different human tissues. Cap-dependent amplification of mRNA 5′ termini and review of public database information were done to more precisely define the NAT2 promoter(s) and to validate the quantitative RT-PCR assay design. The great majority (40/41) of NAT2 liver cDNAs had 5′ termini between 8682 and 8752 nucleotides upstream of the NAT2 ORF exon, and 34 of 40 5′ termini were at the –8711 and –8716 adenines. All 59 NAT2 cDNAs with 5′ termini in this vicinity, including 40 of the liver isolates and 19 cDNAs in public databases from liver and other sources, showed direct splicing to the ORF exon, with no other noncoding exon detected. NAT2 mRNA was highest in liver, small intestine, and colon and was readily detected in most other tissues, albeit at much lower levels. NAT2 expression in diverse human tissues provides further mechanistic support underlying associations between NAT2 genetic polymorphism, drug toxicity, and/or chemical carcinogenesis.
Footnotes
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This work was partially supported by National Institutes of Health Grants CA34627 and ES12557. Portions of this work constituted partial fulfillment for the Ph.D. in pharmacology and toxicology awarded to A.H. from the University of Louisville.
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.106.014621.
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ABBREVIATIONS: NAT2, N-acetyltransferase 2; NAT1, N-acetyltransferase 1; kb, kilobase; ORF, open reading frame; 5′-RLM-RACE, 5′-RNA ligase-mediated rapid amplification of cDNA ends; q-RT-PCR, quantitative reverse transcriptase-polymerase chain reaction; TSS, transcription start site(s); UCSC, University of California, Santa Cruz; HEK, human embryonic kidney; DBTSS, Database of Transcriptional Start Sites; BD, BD Biosciences Clontech; bp, base pair(s).
- Received December 29, 2006.
- Accepted February 6, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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