title: 8-Oxo-7,8-dihydroguanine in DNA does not constitute a barrier to transcription, but is converted into transcription-blocking damage by OGG1.
abstract: The common DNA base modification 8-oxo-7,8-dihydroguanine (8-oxo-G) affects the efficiency and fidelity of transcription. We constructed plasmid substrates carrying single 8-oxo-G residues, specifically positioned in the transcribed or the non-transcribed DNA strands, to investigate their effects on the expression of an EGFP reporter gene and to explore the role of base excision repair in the mechanism of transcription inhibition. We report that 8-oxo-G does not directly block transcription in cells, since a single 8-oxo-G in the transcribed DNA strand did not reduce the EGFP expression levels in repair-deficient (OGG1-null) mouse embryonic fibroblast cell lines. Rather, inhibition of transcription by 8-oxo-G fully depends on 8-oxoguanine DNA glycosylase (OGG1) and, at the same time, does not require the localization of the lesion in the transcribed DNA strand. We propose that the interruption of transcription is induced by base excision repair intermediates and, therefore, could be a common consequence of various DNA base modifications. Concordantly, the non-blocking DNA modification uracil was also found to inhibit transcription, but in an OGG1-independent manner.
authors: Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Staudingerweg 5, 55128 Mainz, Germany.
authors: Nataliya
authors: N
authors: Kitsera
authors: Dimitrios
authors: D
authors: Stathis
authors: Bork
authors: B
authors: Lühnsdorf
authors: Heiko
authors: H
authors: Müller
authors: Thomas
authors: T
authors: Carell
authors: Bernd
authors: B
authors: Epe
authors: Andriy
authors: A
authors: Khobta
mesh_terms: D000818:Animals; D002460:Cell Line; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D045647:DNA Glycosylases / Q000235:genetics / Q000502:physiology*; D004260:DNA Repair; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D051379:Mice; D008957:Models, Genetic; D010957:Plasmids / Q000737:chemistry; D014158:Transcription, Genetic; D014498:Uracil / Q000378:metabolism
chemical_list: C024829:8-hydroxyguanine; D014498:Uracil; D006147:Guanine; D004247:DNA; D045647:DNA Glycosylases; C485990:Ogg1 protein, mouse