Description of a novel polymorphic gene encoding for arylamine N-acetyltransferase in the rhesus macaque (Macaca mulatta), a model animal for endometriosis

OBJECTIVES: Case-control studies have previously associated polymorphisms in the gene encoding the xenobiotic metabolizing enzyme arylamine N-acetyltransferase 2 (NAT2) with endometriosis, a common multifactorial disease in women. These studies, however, have been problematic on methodological grounds and their results are inconclusive. To better understand the possible relationship between the NAT2 gene and endometriosis, we characterized its homologue in the rhesus macaque, an animal model for the disease. METHODS: Human NAT2-specific primers were used to isolate orthologous gene sequences from four unrelated rhesus macaques of the same colony. Recombinant proteins were expressed in mammalian cells and analysed for their ability to acetylate NAT substrates and bind anti-NAT antibodies. RESULTS: A polymorphic gene, showing 94% identity to human NAT2, was identified in the rhesus macaque. Its two characterized alleles, designated (MACMU)NAT2*1 and (MACMU)NAT2*2, were differentiated by one synonymous (C(624)T) and one nonsynonymous (G(691)A) polymorphism, the latter causing a Val(231)Ile substitution. The recombinant (MACMU)NAT2 protein was not recognized by anti-(HUMAN)NAT1 antibody, but reacted with antibodies against (HUMAN)NAT2 or the active site of NAT. Rhesus NAT2 provided relatively high acetylation activity with p-anisidine, lower activity with procainamide, sulphamethazine or 5-aminosalicylate and poor activity with p-aminobenzoic acid. Differences in the activities of the two allozymes were evident with most substrates. CONCLUSIONS: A polymorphic homologue of human NAT2 was characterized in the rhesus macaque, to facilitate investigations of the postulated involvement of this isoenzyme in the toxicogenetics of endometriosis.