Normal human keratinocytes pretreated with damaged mRNA are resistant to UVB damage and exhibit increased DNA repair.
Treatment of normal human keratinocytes with UVC-irradiated rabbit globin mRNA 24 h before and after UVB exposure increased the survival of the human keratinocytes. We also observed that UVC-damaged mRNA reduced the formation of sunburn cells in skin models. We next tested the effects of UVC-damaged mRNA on cellular repair of DNA. DNA repair was evaluated using 2 assay methods. The first method used a damaged plasmid that is transfected back into the cell where it is repaired by the host cell repair mechanism. In these experiments, we observed that externally added UVC-damaged rabbit globin mRNA enhanced the repair of a plasmid transfected into the host keratinocyte cells. The second method used to determine the effects on DNA repair was direct immunostaining for thymidine-thymidine dimers (TT dimers) in histological sections of the skin models. Skin models were irradiated with UVB and then fixed immediately or after 24 h and stained for TT dimers. UVB irradiation immediately caused an increase in the number of stained keratinocytes in the skin. The number of stained cells decreased in skin fixed 24 h after UVB. This is due to repair of the TT dimers and their removal. Sections of skin models pretreated with UV-damaged mRNA exhibit greater removal of these TT dimers after 24 h. The above evidence suggests that damaged mRNA can trigger a host cell DNA repair pathway.
Mammone
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Estee Lauder Research Laboratories, Melville, NY 11747, USA. tmammone@estee.com
Goyarts
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Ingrassia
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Marenus
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D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D019610:Cytoprotection; D004260:DNA Repair; D005914:Globins / Q000235:genetics / Q000528:radiation effects; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000528:radiation effects*; D010957:Plasmids; D011740:Pyrimidine Dimers / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000494:pharmacology* / Q000528:radiation effects; D011817:Rabbits; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D012867:Skin / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D046509:Tissue Culture Techniques; D014466:Ultraviolet Rays / Q000009:adverse effects*
D011740:Pyrimidine Dimers; D012333:RNA, Messenger; D011837:Radiation-Protective Agents; D005914:Globins