Histological localization of acetyltransferases in human tissue.

The localization of human arylamine acetyltransferases (NAT) transcripts was performed by non-isotopic in situ hybridization, utilizing a combination of six NAT1 or NAT2 specific antisense oligonucleotide probes, in order to identify those tissues and organs that might be susceptible to the carcinogenic effects of aromatic amines. The intratissue differences in the level of NAT mRNA were observed: the most abundant NAT2 transcripts were found in hepatocytes, while NAT1 ones dominated in the urothelium and in the colon epithelial cells. The specific NAT1 and NAT2 mRNAs were present also in the epithelial lining of the lung bronchi, the mammary gland and the small intestine epithelial cells, the outer layer of placenta syncytiotrophoblast cells, the kidney tubules, and the pineal gland. Qualitative differences in the sites of mRNA of these two enzymes were seen only in the kidney specimens, in which NAT2 was expressed in both proximal and distal tubules, and the NAT1 was detected only in the former ones.