| Summary: | <p>Arylamine N-acetyltransferases are xenobiotic metabolising enzymes, involved in metabolic pathways leading to either detoxification or bio-activation of drugs and carcinogens. In humans, polymorphisms of the two functional NAT genes (<em>NAT1</em> and <em>NAT2</em>} have been implicated to cancer susceptibility. The genomic region of the <em>NAT1</em> loci, 8p22, is often deleted in tumours and is believed to contain tumour suppressor genes. Two previously developed cosmid probes, carrying either <em>NAT1</em> or <em>NAT2</em>, were tested as probes for FISH analysis using nuclei from healthy lymphocytes and the RT112 urothelial carcinoma cell line (Chapter 3). FISH analysis of cells obtained from barbotage samples of bladder cancer patients was performed and deletion of the <em>NAT</em> genomic region was a common observation (Chapter 6). To allow refined mapping of the <em>NAT</em> region on 8p22, a series of PAC clones carrying the <em>NAT</em> loci were isolated by PCR screening of a genomic library (Chapter 3). Furthermore, the NAT1 and NAT2 isoenzymes were studied in healthy intestinal and mammary tissue, as a first step towards understanding their potential involvement in these two types of cancer (Chapter 6).</p> <p>The mouse has been extensively used as a model for studying NAT. Three functional <em>Nat</em> genes are present in the mouse genome. A fine restriction map was generated for the <em>Nat1</em> and <em>Nat2</em> genomic region in mice, using <em>Nat</em>-positive genomic DNA plasmid clones previously isolated from the fast acetylator Balb/c and 129/Ola strains. The <em>Nat1</em> and <em>Nat2</em> genes were mapped 9.4kb apart and no polymorphisms were detected between the two strains for the restriction enzymes used for mapping (Chapter 4). The 129/Ola restriction map has since been the basis for the production of a construct for <em>Nat2</em> knockout and transgenic mouse strains. PAC clones positive for <em>Nat</em> were isolated from a mouse genomic library and used as FISH probes to map the three murine <em>Nat</em> genes on chromosome 8, band B3.1-3.3. One PAC clone contained all three <em>Nat</em> loci, establishing co-localisation of <em>Nat3</em> with the other two <em>Nat</em> genes in mice. The minimum distance of <em>Nat3</em> from <em>Nat1</em> and <em>Nat2</em> was estimated to be 22kb, while the three loci are within 130kb. YAC clones carrying the <em>Nat</em> genes were also isolated to facilitate physical mapping of the <em>Nat</em> cluster in mice (Chapter 5). This will allow integration of cytogenetic, physical and previous genetic data for comparative studies.</p>
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