title: H2O2 signals via iron induction of VL30 retrotransposition correlated with cytotoxicity.
abstract: The impact of oxidative stress on mobilization of endogenous retroviruses and their effects on cell fate is unknown. We investigated the action of H2O2 on retrotransposition of an EGFP-tagged mouse LTR-retrotransposon, VL30, in an NIH3T3 cell-retrotransposition assay. H2O2 treatment of assay cells caused specific retrotranspositions documented by UV microscopy and PCR analysis. Flow cytometric analysis revealed an unusually high dose- and time-dependent retrotransposition frequency induced, ∼420,000-fold at 40 μM H2O2 compared to the natural frequency, which was reduced by ectopic expression of catalase. Remarkably, H2O2 moderately induced the RNA expression of retrotransposon B2 without affecting the basal expression of VL30s and L1 and significantly induced the expression of various endogenous reverse transcriptase genes. Further, whereas treatment with 50 μM FeCl2 alone was ineffective, cotreatment with 10 μM H2O2 and 50 μM FeCl2 caused a 6-fold higher retrotransposition induction than H2O2 alone, which was associated with cytotoxicity. H2O2- or H2O2/FeCl2-induced retrotransposition was significantly reduced by the iron chelator DFO or the antioxidant NAC, respectively. Furthermore, both H2O2-induced retrotransposition and associated cytotoxicity were inhibited after pretreatment of cells with DFO or the reverse transcriptase inhibitors efavirenz and etravirine. Our data show for the first time that H2O2, acting via iron, is a potent stimulus of retrotransposition contributing to oxidative stress-induced cell damage.
authors.affiliation: Laboratory of General Biology, University of Ioannina, and Hematology Laboratory, Unit of Molecular Biology, University Hospital of Ioannina, 45 110 Ioannina, Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Konisti
authors.forename: Stefania
authors.initials: S
authors.lastname: Mantziou
authors.forename: Georgios
authors.initials: G
authors.lastname: Markopoulos
authors.forename: Soteroula
authors.initials: S
authors.lastname: Thrasyvoulou
authors.forename: Georgios
authors.initials: G
authors.lastname: Vartholomatos
authors.forename: Ioannis
authors.initials: I
authors.lastname: Sainis
authors.forename: Evangelos
authors.initials: E
authors.lastname: Kolettas
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Noutsopoulos
authors.forename: Theodore
authors.initials: T
authors.lastname: Tzavaras
mesh_terms: D016475:3T3 Cells; D000480:Alkynes; D000818:Animals; D000975:Antioxidants; D048588:Benzoxazines / Q000494:pharmacology; D002374:Catalase / Q000096:biosynthesis / Q000378:metabolism; D002460:Cell Line; D003521:Cyclopropanes; D049452:Green Fluorescent Proteins / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D051379:Mice; D009570:Nitriles; D018384:Oxidative Stress; D011724:Pyridazines / Q000494:pharmacology; D011743:Pyrimidines; D012367:RNA, Viral / Q000096:biosynthesis; D012194:RNA-Directed DNA Polymerase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D018626:Retroelements / Q000235:genetics*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction
chemical_list: D000480:Alkynes; D000975:Antioxidants; D048588:Benzoxazines; D003521:Cyclopropanes; D009570:Nitriles; D011724:Pyridazines; D011743:Pyrimidines; D012367:RNA, Viral; D018626:Retroelements; D018894:Reverse Transcriptase Inhibitors; C451734:etravirine; D049452:Green Fluorescent Proteins; D006861:Hydrogen Peroxide; D007501:Iron; D002374:Catalase; D012194:RNA-Directed DNA Polymerase; C098320:efavirenz