Pancreatic islets are very poor in rectifying oxidative DNA damage.
OBJECTIVE
Free radicals that escape scavenging by antioxidant defense damage lipids, proteins, and DNA. Damage to DNA can be repaired. Therefore, both cells' antioxidant defense and their ability to repair oxidatively damaged DNA decide its fate to survive oxidative stress. Pancreatic islets cells with poor antioxidant defense were checked for their ability to remove oxidative damage form DNA.


METHODS
For ex vivo DNA repair, assay-cultured pancreatic islets and liver slices were treated with 1 and 10 mM H2O2, respectively, for 30 minutes. After incubation for different time intervals, 8-hydroxy-2'-deoxyguanosine (8-OHdG) in DNA of these cells was estimated using monoclonal antibody raised against 8-OHdG by competitive enzyme-linked immunosorbent assay. For in vitro DNA repair assay, oxidatively damaged pBR322 was incubated with nuclear extracts of islet and liver cells, and 8-OHdG retained in the plasmid was quantitated.


RESULTS
Oxidative damage induced by H2O2 was removed quickly and efficiently from DNA by liver cells compared with islet cells. The repair of oxidatively damaged plasmid DNA in vitro was also performed more efficiently (P < 0.05) by nuclear extracts from liver cells compared with islet cell.


CONCLUSIONS
We clearly demonstrate that in addition to their low antioxidant defense, islets are very poor in rectifying the oxidative DNA damage.
Modak
Manisha A
MA
Department of Zoology, University of Pune, Ganeshkhind, Pune, India.
Parab
Pradeep Bhaskar
PB
Ghaskadbi
Saroj S
SS
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D000911:Antibodies, Monoclonal; D000975:Antioxidants / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D004249:DNA Damage; D004260:DNA Repair; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000276:immunology / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006861:Hydrogen Peroxide / Q000633:toxicity; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D016877:Oxidants / Q000633:toxicity; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D046509:Tissue Culture Techniques
D000911:Antibodies, Monoclonal; D000975:Antioxidants; D015415:Biomarkers; D016877:Oxidants; D017382:Reactive Oxygen Species; D000080242:8-Hydroxy-2'-Deoxyguanosine; D006861:Hydrogen Peroxide; D003849:Deoxyguanosine