Disease relevance of Nat2

• The Nat2 promoter consists of an atypical TATA box and a Sp1 [SV40 (simian virus 40) protein 1] box identical with that found in many housekeeping gene promoters [1].
• The cytomegalovirus (CMV)-promoted NAT1 transgene increased endogenous Nat1 mRNA levels in liver and had little effect on endogenous Nat2 mRNA levels [2].
• Two genes (NAT1, NAT2) have been identified and allelic variation in NAT2 has been associated with arylamine toxicity in adults [3].
• To investigate the role of prostate-specific expression of human N-acetyltransferase 2 (NAT2) on PhIP-induced prostate cancer, we constructed a transgenic mouse model that targeted expression of human NAT2 to the prostate [4].

High impact information on Nat2

• NAT1 and NAT2 transcripts were completely undetectable in the Nat1/2(-/-) mice [5].
• The in vitro N-acetylation of p-aminosalicylate was detected at significant levels in liver and kidney cytosols from either wild-type inbred 'rapid acetylator' C57BL/6 mice or from outbred CD-1 mice possessing homozygous rapid, heterozygous, or homozygous 'slow acetylator' Nat2 genotypes [5].
• To facilitate the study of these processes, we have generated a Nat1/Nat2 double-knockout mouse model by gene targeting in embryonic stem cells [5].
• The genomic clone encoding NAT-1 is identical in rapid and slow acetylator mouse strains, whereas the clone encoding NAT-2 differs between rapid and slow strains by a single base pair, which changes the encoded amino acid from Asn99 in the rapid acetylator strain to Ile99 in the slow acetylator strain [6].
• Only Nat2 has been shown previously to be polymorphic, a single nucleotide substitution causing the slow acetylator phenotype in the A/J strain [7].

Biological context of Nat2

• Different alleles at the Nat2 locus are responsible for the acetylation polymorphism identified in different mouse strains [8].
• Chromosome mapping of the genes for murine arylamine N-acetyltransferases (NATs), enzymes involved in the metabolism of carcinogens: identification of a novel upstream noncoding exon for murine Nat2 [8].
• Examination of the 13 kb sequence flanking the coding and non-coding exons of Nat2 revealed a single promoter, located close to the transcription-initiation site, and indicated regions likely to harbour control elements [1].
• Database searches and analyses of cDNA by PCR suggested alternative splicing of the single 6.2 kb intron of Nat2, and determined the position of the polyadenylation signal at 0.44 kb downstream of the coding region of the gene [1].
• The human NAT loci (NAT1, NAT2, and a pseudogene, NATP) have been mapped to human chromosome 8p22, a region frequently deleted in tumours [8].

Anatomical context of Nat2

• Whereas Nat2 expression is not detected in ventricular myocardial cells, Nat2 is strongly expressed in scattered cells in the region of the sinus node, the epicardium of the right atrial appendage, and in the pulmonary artery [9].
• NAT2 was also detected in epithelial cells in the lung, kidney, bladder, small intestine and skin as well as in erythrocytes and lymphocytes in the spleen and hair follicles and sebaceous glands in the skin [10].
• Immunohistochemical staining of C57BL/6J liver with anti-NAT2 antiserum showed that NAT2 was expressed in hepatocytes throughout the liver although the intensity of staining in the perivenous (centrilobular) region was higher than that in the periportal region [10].
• Immunohistochemical staining of the adult mouse cerebellum revealed NAT2 (the mouse homologue of human NAT1) expression in the cell bodies and dendrites of Purkinje cells and in the neuroglia of the molecular layer [11].
• We show here that functional NAT1 and NAT2 isoforms are expressed in mouse myotubes and that peroxynitrite may impair their activity in these cells [12].

Associations of Nat2 with chemical compounds

• N-acetyltransferase activity toward the aromatic amine carcinogen 4-aminobiphenyl and O-acetyltransferase activity toward its proximate metabolite N-hydroxy-4-aminobiphenyl were both present in tissue cytosols of WT mice but were undetectable in Nat2 KO mice [13].
• For the substrates tested in this study, mouse Nat3 exhibited activity only toward 5-aminosalicylic acid and only at 1/20 the activity shown by Nat2 [14].
• Together with recent discoveries regarding the effects of testosterone on the expression of Nat2* in mouse kidney during development, the findings reported in this article suggest that the HRE found in the promoter region of Nat2* is a potential candidate for the mediation of androgenic regulation of Nat2* in mouse kidney [15].
• The kidney p-aminobenzoic acid/Nat2-acetylating activity of CD-1 female mice showed a 2.5-fold increase at 80 days of age compared with day 1, whereas males showed a 4.3-fold increase at 25 days and a 5.8-fold increase at 80 days [16].
• We propose that the observed increase in Nat2 transcript expression in male mice may be a result of androgen regulation during development [16].

Other interactions of Nat2

• In wild-type mice, NAT1 and NAT2 transcripts were detectable by RT-PCR in all tissues assayed including liver, kidney, colon, brain, bladder, and spleen [5].
• Recombinant NAT1, NAT2, and NAT3 proteins catalyzed N-, O-, and N,O-acetyltransferase activities [17].

Analytical, diagnostic and therapeutic context of Nat2

• Nat1- and Nat2-specific mRNA, determined by quantitative real-time polymerase chain reaction, was detected in all tissues examined and did not differ significantly (p > 0.05) between Nat2 KO and WT mice [13].
• Western blot analysis indicated that hepatic NAT2 protein is less abundant in M. spretus than M. m. castaneus [7].
• Enzyme-linked immunosorbent assays (ELISAs) demonstrated that the anti-NAT2 antiserum bound in a concentration-dependent fashion to recombinant NAT2 [10].
• Northern blotting and immunoblotting revealed hepatic NAT2 mRNA and protein bands of equal size and intensity, regardless of the NAT2* genotype or phenotype of the animals [18].

References