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Original

The contribution of DNA repair and antioxidants in determining cell type-specific resistance to oxidative stress

, &
Pages 1155-1165 | Received 25 Feb 2006, Published online: 07 Jul 2009
 

Abstract

The aims of this study were; (i) to elucidate the mechanisms involved in determining cell type-specific responses to oxidative stress and (ii) to test the hypothesis that cell types which are subjected to high oxidative burdens in vivo, have greater oxidative stress resistance. Cultures of the retinal pigment epithelium (RPE), corneal fibroblasts, alveolar type II epithelium and skin epidermal cells were studied. Cellular sensitivity to H2O2 was determined by the MTT assay. Cellular antioxidant status (CuZnSOD, MnSOD, GPX, CAT) was analyzed with enzymatic assays and the susceptibility and repair capacities of nuclear and mitochondrial genomes were assessed by QPCR. Cell type-specific responses to H2O2 were observed. The RPE had the greatest resistance to oxidative stress (P>0.05; compared to all other cell types) followed by the corneal fibroblasts (P < 0.05; compared to skin and lung cells). The oxidative tolerance of the RPE coincided with greater CuZnSOD, GPX and CAT enzymatic activity (P < 0.05; compared to other cells). The RPE and corneal fibroblasts both had up-regulated nDNA repair post-treatment (P < 0.05; compared to all other cells). In summary, variations in the synergistic interplay between enzymatic antioxidants and nDNA repair have important roles in influencing cell type-specific vulnerability to oxidative stress. Furthermore, cells located in highly oxidizing microenvironments appear to have more efficient oxidative defence and repair mechanisms.

Abbreviations
AMD=

age-related macular degeneration

CAT=

catalase

CuZnSOD=

copper zinc superoxide dismutase

GPX=

glutathione peroxidase

MnSOD=

manganese superoxide dismutase

MTT=

3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide

ROS=

reactive oxygen species

RPE=

retinal pigment epithelium

mtDNA=

mitochondrial DNA

nDNA=

nuclear DNA

QPCR=

quantitative polymerase chain reaction

Abbreviations
AMD=

age-related macular degeneration

CAT=

catalase

CuZnSOD=

copper zinc superoxide dismutase

GPX=

glutathione peroxidase

MnSOD=

manganese superoxide dismutase

MTT=

3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide

ROS=

reactive oxygen species

RPE=

retinal pigment epithelium

mtDNA=

mitochondrial DNA

nDNA=

nuclear DNA

QPCR=

quantitative polymerase chain reaction

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