| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2146498 | Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis | 2012 | 11 Pages |
The catechol-mediated DNA damage in the presence of Cu(II) ions involves oxidation of guanine to 8-oxoguanine (8-oxoG) and DNA strand scission. It proceeds through the reactive oxygen species (ROS) generation. The mutagenicity of 8-oxoG lesions is due to its miscoding propensity reflected in GC→TA transversion taking place during the DNA repair process. To gain new insights into the nature of catechol-mediated DNA damage and its prevention, we have investigated the changes in DNA melting characteristics and 8-oxoG formation as the indicators of DNA damage in a model calf-thymus DNA system. A novel fluorescence method for DNA melting temperature determination, based on DAPI fluorescent-probe staining, has been proposed. The DNA melting-onset temperature has been found to be more sensitive to DNA damage than the standard melting temperature due to the increased width of the melting transition observed in oxidatively damaged DNA. We have found that the efficiency of Fenton cascade in generating DNA-damaging ROS is higher for catechol than for GSH, two strong antioxidants, mainly due to the much longer distance between ROS-generating radical group in GS to nucleobases than that of semiquinone radical group to nucleobases (2.1 nm vs. 0.27 nm), making the ROS transport from GSH an order of magnitude less likely to damage DNA because of short lifetime of HO radicals. The antioxidant and DNA-protecting behaviors of GSH have been elucidated. We have found that the redox potential of GSH/GSSG couple is lower than that of catechol/semiquinone couple. Hence, GSH keeps catechol in the reduced state, thereby shutting down the initial step of the catechol-mediated Fenton cascade. The catechol-induced DNA damage in the presence of Cu(II) ions has also been confirmed in studies of ON–OFF hairpin-oligonucleotide beacons.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New evidence for catechol-mediated DNA-damage in the presence of Cu(II) is presented. ► Damage assessment using melting-onset analysis with fluorophore DAPI is proposed. ► Glutathione and N-acetylcysteine prevent catechol-mediated DNA damage. ► Mechanisms of DNA base oxidation and strand scission have been elucidated. ► Catechol-mediated DNA damage has been confirmed with fluorescent hairpin beacons.
