title: Age-related changes in the induction of DNA polymerases in rat liver by gamma-ray irradiation.
abstract: DNA polymerase activities related to DNA repair were examined in the livers of young (6-month-old) and aged (27-month-old) rats irradiated with gamma-rays. The activity of DNA polymerase alpha was little changed in the livers of gamma-ray-irradiated rats, while DNA polymerases beta and gamma were induced in the livers of young and aged rats exposed by gamma-ray irradiation. These enzymes were induced from 2 to 6 h after irradiation of young and aged rats, respectively, although the induction in aged rats was weak. DNA polymerase beta activity in the livers of young rats irradiated with gamma-rays was 2-fold that in aged rats. Similarly, DNA polymerase gamma activity in the livers of young rats subjected to gamma-ray irradiation was 3-fold that in aged rats. The induction of proliferating cell nuclear antigen (PCNA) in the livers of aged rats irradiated with gamma-rays was also delayed compared with young rats. These results indicate that the decline in repair activity in aged rats leads to the accumulation of oxidative damage and DNA mutations in aged tissues.
authors.affiliation: Redox Regulation Research Group, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan. kaneko@tmig.or.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Kaneko
authors.forename: Shoichi
authors.initials: S
authors.lastname: Tahara
authors.forename: Munehiko
authors.initials: M
authors.lastname: Tanno
authors.forename: Takahiko
authors.initials: T
authors.lastname: Taguchi
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000375:Aging / Q000502:physiology*; D000818:Animals; D004249:DNA Damage; D004256:DNA Polymerase I / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism*; D000074002:DNA Polymerase gamma; D004260:DNA Repair; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D004790:Enzyme Induction / Q000528:radiation effects; D005720:Gamma Rays; D008099:Liver / Q000201:enzymology* / Q000528:radiation effects*; D008297:Male; D018384:Oxidative Stress; D011089:Polydeoxyribonucleotides / Q000378:metabolism / Q000528:radiation effects; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D011089:Polydeoxyribonucleotides; D018809:Proliferating Cell Nuclear Antigen; C019530:poly(dC-dG); D000080242:8-Hydroxy-2'-Deoxyguanosine; D004256:DNA Polymerase I; D019951:DNA Polymerase beta; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase; D003849:Deoxyguanosine