LOCALIZATION OF POLYMORPHIC N-ACETYLTRANSFERASE (NAT2) IN TISSUES OF INBRED MICE

Like humans, mice exhibit polymorphism in the N-acetylation of aromati c amines, many of which are toxic and/or carcinogenic. Mice have three N-acetyltransferase (Nat) genes, Nat1, Nat2 and Nat3 and Nat2 is know n to be polymorphic. There is a dramatic difference in the acetylation of NAT2 substrates by blood from fast (C57BL/6J) compared with slow a cetylator (A/J) mice. However, the acetylation of these substrates by liver cytosols from the two strains is very similar. In order to deter mine whether the expression of the NAT2 protein corresponded with the activities measured, a polyclonal antipeptide antisera was raised agai nst the C-terminal decapeptide of NAT2 and characterized using recombi nant murine NAT2 antigen. Enzyme-linked immunosorbent assays (ELISAs) demonstrated that the anti-NAT2 antiserum bound in a concentration-dep endent fashion to recombinant NAT2. Immunochemical analysis of mouse l iver cytosols from C57BL/6J or A/J livers indicated that the level of NAT2 protein expressed in the two strains was similar. Immunohistochem ical staining of C57BL/6J liver with anti-NAT2 antiserum showed that N AT2 was expressed in hepatocytes throughout the liver although the int ensity of staining in the perivenous (centrilobular) region was higher than that in the periportal region. NAT2 was also detected in epithel ial cells in the lung, kidney, bladder, small intestine and skin as we ll as in erythrocytes and lymphocytes in the spleen and hair follicles and sebaceous glands in the skin. Characterization of the distributio n of NAT2 will be of value in elucidating the role of polymorphic N-ac etylation in protecting the organism from environmental insults as wel l as in endogenous metabolism.