Localization of aflatoxin B1--nucleic acid adducts in mitochondria and nuclei.
The reaction of chemical carcinogens with cellular macromolecules, particularly DNA, is considered to be an important event during chemical carcinogenesis. Until recently, most studies have dealt primarily with nuclear DNA (nDNA). Mitochondrial DNA (mtDNA) is increasingly being investigated for its possible role during chemical carcinogenesis. Using monoclonal antibodies against aflatoxin B1 (AFB1)-modified guanosine and ultrastructural immunocytochemistry, we have localized the AFB1-guanosine adducts predominantly in mitochondria and nuclei. Morphometric analysis of the electron micrographs demonstrates that localization of the AFB1-guanosine adducts is several-fold greater in mitochondria than in the nuclei. However, biochemical analysis demonstrates that 77% of the covalent binding was detected in nucleic acids of the mitochondria relative to the nuclear fractions. In RNA-free preparations, the extent of covalent modification of mt circular DNA was less than 50% of that of nuclear DNA. Our results indicate that 67% of AFB1 binding to mitochondrial nucleic acids is associated primarily with mtRNA.
D016604:Aflatoxin B1; D000348:Aflatoxins / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal; D001345:Autoradiography; D002467:Cell Nucleus / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004270:DNA, Circular / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism; D006651:Histocytochemistry; D008297:Male; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344
D000348:Aflatoxins; D000911:Antibodies, Monoclonal; D004270:DNA, Circular; D004272:DNA, Mitochondrial; D004247:DNA; D016604:Aflatoxin B1