Absence of superoxide dismutase activity causes nuclear DNA fragmentation during the aging process.
Superoxide dismutases (SOD) serve as an important antioxidant defense mechanism in aerobic organisms, and deletion of these genes shortens the replicative life span in the budding yeast Saccharomyces cerevisiae. Even though involvement of superoxide dismutase enzymes in ROS scavenging and the aging process has been studied extensively in different organisms, analyses of DNA damages has not been performed for replicatively old superoxide dismutase deficient cells. In this study, we investigated the roles of SOD1, SOD2 and CCS1 genes in preserving genomic integrity in replicatively old yeast cells using the single cell comet assay. We observed that extend of DNA damage was not significantly different among the young cells of wild type, sod1Δ and sod2Δ strains. However, ccs1Δ mutants showed a 60% higher amount of DNA damage in the young stage compared to that of the wild type cells. The aging process increased the DNA damage rates 3-fold in the wild type and more than 5-fold in sod1Δ, sod2Δ, and ccs1Δ mutant cells. Furthermore, ROS levels of these strains showed a similar pattern to their DNA damage contents. Thus, our results confirm that cells accumulate DNA damages during the aging process and reveal that superoxide dismutase enzymes play a substantial role in preserving the genomic integrity in this process.
Izmir Institute of Technology, Department of Molecular Biology & Genetics, 35430 Urla, Izmir, Turkey.
Khandaker Ashfaqul
KA
Muid
Izmir Institute of Technology, Department of Molecular Biology & Genetics, 35430 Urla, Izmir, Turkey.
Hüseyin Çaglar
HÇ
Karakaya
Izmir Institute of Technology, Department of Molecular Biology & Genetics, 35430 Urla, Izmir, Turkey. Electronic address: ahmetkoc@iyte.edu.tr.
Ahmet
A
Koc
D002467:Cell Nucleus / Q000235:genetics; D020552:Comet Assay; D004249:DNA Damage; D053938:DNA Fragmentation; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D050296:Microbial Viability / Q000235:genetics; D018613:Microscopy, Confocal; D018832:Molecular Chaperones / Q000235:genetics; D009154:Mutation; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D013482:Superoxide Dismutase / Q000235:genetics*; D000072105:Superoxide Dismutase-1; D013997:Time Factors; D000099156:Superoxide Dismutase 2
D004271:DNA, Fungal; D018832:Molecular Chaperones; D017382:Reactive Oxygen Species; D029701:Saccharomyces cerevisiae Proteins; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2; C491960:CCS1 protein, S cerevisiae
Aging; Antioxidant; Comet assay; DNA damage; Longevity; Oxidative stress; ROS; Reactive oxygen species; SOD; Superoxide dismutase