Abstract
The human N-acetyltransferase (Nat2) genetic polymorphisms have been modeled in mouse strains. We determined the phenotype and genotype of the N-acetyltransferase 2 (Nat2*) gene among outbred CD-1 mice and found a mixed population of heterozygous and rapid and slow homozygous genotypes. Phenotypes determined with p-aminobenzoic acid demonstrated complete concordance of slow and rapid genotype and phenotype. 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. Immunoblot analysis revealed a 2-fold increase in male kidney Nat immunoreactive protein at 80 days of age, whereas no significant differences were detected in female mice. Likewise, the Nat2 mRNA levels determined by ribonuclease protection assay showed an increase in transcript levels in kidney of male mice during postnatal development, whereas they remained unchanged in females. Gender-associated differences of Nat2 activity, protein, and transcript levels were absent in liver. These observations suggest that the increase in Nat2 enzymatic activity in kidney is accomplished by an increase in transcript. We propose that the observed increase in Nat2 transcript expression in male mice may be a result of androgen regulation during development.
Footnotes
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Send reprint requests to: Dr. Lourdes Estrada, 3570 MSRBII, 1150 W. Medical Center Drive, The University of Michigan, Ann Arbor, MI 48109-0688. E-mail: lestrada{at}mailexcite.com
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This work was submitted in partial fulfillment of requirements for a Ph.D. degree in Pharmacology (The University of Michigan, Ann Arbor, MI) and was supported by National Institutes of Health Grants GM44965 and CA39018.
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↵2 The Nat1* nucleotide sequence published by Martell et al. (1991) was initially reported for A/J and C57BL/6J mouse strains with ATC for nucleotide positions 73 to 75 (coding for Ile25). More recently, Kelly and Sim (1994), reported an ACT codon for BALB/c and A/J mouse strains. Reexamination of the Nat1* sequence from C57BL/6J and A/J mouse strains in our laboratory (L. Estrada-Rodgers, unpublished observation) confirmed the nucleotide sequence reported byKelly and Sim (1994). Therefore, deduced mouse Nat1* has a threonine at position 25 instead of isoleucine. The corrected sequence can be found at GenBank accession number U35885.
- Abbreviations used are::
- Nat
- N-acetyltransferase
- PABA
- p-aminobenzoic acid
- HRE
- hormone response element
- PCR
- polymerase chain reaction
- CoA
- coenzyme A
- Received June 16, 1999.
- Accepted October 27, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
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