Cellular prion protein protects against reactive-oxygen-species-induced DNA damage.
Although the cellular form of the prion protein (PrPC) is critical for the development of prion disease through its conformational conversion into the infectious form (PrPSc), the physiological role of PrPC is less clear. Using alkaline single-cell gel electrophoresis (the Comet assay), we show that expression of PrPC protects human neuroblastoma SH-SY5Y cells against DNA damage under basal conditions and following exposure to reactive oxygen species, either hydroxyl radicals following exposure to Cu2+ or Fe2+ or singlet oxygen following exposure to the photosensitizer methylene blue and white light. Cells expressing either PrPDeltaoct which lacks the octapeptide repeats or the prion-disease-associated mutants A116V or PG14 had increased levels of DNA damage compared to cells expressing PrPC. In PrPSc-infected mouse ScN2a cells there was a significant increase in DNA damage over noninfected N2a cells (median tail DNA 2.87 and 7.33%, respectively). Together, these data indicate that PrPC has a critical role to play in protecting cells against reactive-oxygen-species-mediated DNA damage; a function which requires the octapeptide repeats in the protein, is lost in disease-associated mutants of the protein or upon conversion to PrPSc, and thus provide further support for the neuroprotective role for PrPC.
Watt
Nicole T
NT
Proteolysis Research Group, Institute of Molecular and Cellular Biology, Faculty of Biological Sciences and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT, UK.
Routledge
Michael N
MN
Wild
Christopher P
CP
Hooper
Nigel M
NM
D000818:Animals; D045744:Cell Line, Tumor; D020552:Comet Assay; D004249:DNA Damage; D043382:DNA-Formamidopyrimidine Glycosylase / Q000378:metabolism; D006801:Humans; D051379:Mice; D018384:Oxidative Stress; D018621:PrPC Proteins / Q000235:genetics / Q000378:metabolism*; D017096:Prion Diseases / Q000235:genetics; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors* / Q000633:toxicity; D026082:Singlet Oxygen / Q000633:toxicity
D018621:PrPC Proteins; D017382:Reactive Oxygen Species; D026082:Singlet Oxygen; D043382:DNA-Formamidopyrimidine Glycosylase