title: Age- and tissue-specific changes in mitochondrial and nuclear DNA base excision repair activity in mice: Susceptibility of skeletal muscles to oxidative injury.
abstract: In this study, we investigated age- and tissue-dependent changes in the DNA base excision repair (BER) of oxidative lesions in mitochondrial and nuclear extracts by measuring single-nucleotide (SN)- and long-patch (LP)-BER activities in five tissues isolated from 4-, 10- and 20-month-old mice. Age-dependent SN-BER and LP-BER activity was increased in the mitochondria of liver, kidney and heart, but generally decreased in skeletal muscles. In contrast, no significant changes in repair activity were observed in nuclear extracts of the same tissues, except for quadriceps, where the SN-BER activity was higher in the old animals. Moreover, the BER activities in both the nucleus and the mitochondria were significantly lower in skeletal muscles compared to liver or kidney of the same mice. The protein level of three antioxidant enzymes, Mn and Cu/Zn superoxide dismutases (SOD) and catalase, was also significantly lower in skeletal muscle compared to liver or kidney. In addition, we found higher levels of protein carbonylation in the mitochondria of skeletal muscle relative to other tissues. Thus, it appears likely that mouse skeletal muscle is highly susceptible to oxidative stress due to deficiency in both repair of oxidative DNA damage and antioxidant enzymes, contributing to age-dependent muscle loss.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1079, USA. baszczes@utmb.edu
authors.forename: Bartosz
authors.initials: B
authors.lastname: Szczesny
authors.forename: Anne W
authors.initials: AW
authors.lastname: Tann
authors.forename: Sankar
authors.initials: S
authors.lastname: Mitra
mesh_terms: D000375:Aging / Q000235:genetics*; D000818:Animals; D002467:Cell Nucleus / Q000235:genetics*; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000235:genetics*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology*; D018384:Oxidative Stress / Q000235:genetics*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D013482:Superoxide Dismutase; D002950:Citrate (si)-Synthase