title: Oxidative DNA damage is epigenetic by regulating gene transcription via base excision repair.
abstract: Reactive oxygen species (ROS) have emerged as important cellular-signaling agents for cellular survival. Herein, we demonstrate that ROS-mediated oxidation of DNA to yield 8-oxo-7,8-dihydroguanine (OG) in gene promoters is a signaling agent for gene activation. Enhanced gene expression occurs when OG is formed in guanine-rich, potential G-quadruplex-forming sequences (PQS) in promoter-coding strands, initiating base excision repair (BER) by 8-oxoguanine DNA glycosylase (OGG1), yielding an abasic site (AP). The AP enables melting of the duplex to unmask the PQS, adopting a G-quadruplex fold in which apurinic/apyrimidinic endonuclease 1 (APE1) binds, but inefficiently cleaves, the AP for activation of vascular endothelial growth factor (VEGF) or endonuclease III-like protein 1 (NTHL1) genes. These details were mapped via synthesis of OG and AP analogs at single-nucleotide precision within the promoter of a luciferase reporter system. The reporters were analyzed in human and mouse cells while selectively knocking out or down critical BER proteins to identify the impact on luciferase expression. Identification of the oxidatively modified DNA base OG to guide BER activity in a gene promoter and impact cellular phenotype ascribes an epigenetic role to OG.
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112-0850 burrows@chem.utah.edu afleming@chem.utah.edu.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Fleming
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112-0850.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112-0850 burrows@chem.utah.edu afleming@chem.utah.edu.
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Burrows
mesh_terms: D000818:Animals; D004249:DNA Damage / Q000235:genetics*; D045647:DNA Glycosylases / Q000737:chemistry / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000737:chemistry / Q000235:genetics; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000737:chemistry / Q000235:genetics; D044127:Epigenesis, Genetic / Q000235:genetics; D054856:G-Quadruplexes; D005786:Gene Expression Regulation / Q000235:genetics; D006147:Guanine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D051379:Mice; D018384:Oxidative Stress / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry / Q000235:genetics
chemical_list: D017382:Reactive Oxygen Species; D042461:Vascular Endothelial Growth Factor A; C024829:8-hydroxyguanine; D006147:Guanine; D043224:Deoxyribonuclease (Pyrimidine Dimer); C468347:NTHL1 protein, human; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase
keywords: G-quadruplex; base excision repair; epigenetics; gene regulation; oxidative damage