miR-200a Modulates the Expression of the DNA Repair Protein OGG1 Playing a Role in Aging of Primary Human Keratinocytes

Figure 3

DNA repair system efficiency in 8-OH-dG removal in aged and senescent primary human keratinocytes. (a) BER enzyme expression was evaluated by quantitative RT-PCR analysis on RNA extracted from young and old donors at 2nd passage. Data were shown as fold change (, , by Student’s test). (b) BER enzyme expression was evaluated by quantitative RT-PCR analysis on RNA extracted from early and late passages of primary human keratinocyte cultures. Data were shown as fold change (, , by Student’s test). (c) MMR enzyme expression was evaluated by quantitative RT-PCR analysis on RNA extracted from young and old donors at 2nd passage. Data were shown as fold change (, , by Student’s test). (d) MMR enzyme expression was evaluated by quantitative RT-PCR analysis on RNA extracted from early and late passages of primary human keratinocyte cultures. Data were shown as fold change (, by Student’s test). (e) The ability of keratinocyte extracts from young and old donors (at 2nd passage) to repair the 8-OH-dG residues was tested in vitro using Rhodamine Green-labelled plasmid substrates containing 8-OH-dG. After incubation, plasmid DNA was submitted to SDS-PAGE to detect the fluorescence intensity of full-length DNAs and cleaved fragments by image analysis. The results were expressed as the cleavage percentage correlated to cell extract amount.

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