Small Molecule Ogg1 Activators Ameliorate mtDNA Oxidation and Promote Cell Health

• Published in: The FASEB journal Vol. 30; no. S1
• Main Authors: Katchur, Steven R, Davis, Alicia M, Ellis, Elizabeth, Pickard, Benjamin, Pyne, Susan, Rumsey, William
• Format: Journal Article
• Language: English
• Published: 01-04-2016
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.30.1_supplement.791.3

Abstract only Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow limitation, loss of the alveolar unit, and increased levels of oxidative damage to macromolecules, including DNA. 8‐oxoguanine (8‐OG) is the most common oxidative DNA lesion and its removal and repair is executed through the base excision repair pathway (BER). The purpose of this study was to determine whether enhancing the activity of the DNA glycosylase, Ogg1, would benefit epithelial cell health during an oxidative challenge. Paraquat, an herbicide that intercalates within the inner mitochondrial membrane was used in combination with A549 cells to produce excessive amounts of reactive oxygen species. Levels of 8‐OG were measured using immunofluorescence and single cell phenotypic analysis was undertaken using a high content imaging platform. Transduction of A549 cells with full length‐Ogg1 baculovirus lowered the maximal levels of 8‐OG in mtDNA by 200% as compared to null virus control cells. Conversely, administration of Ogg1 siRNA rendered the cells more vulnerable to paraquat, increasing 8‐OG content by almost 500%. Exemplars of small molecule Ogg1 activators identified through a high‐throughput‐screen, were shown to reduce paraquat‐induced 8‐OG formation by approximately 50%. Moreover, Ogg1 activators improved paraquat‐induced loss of mitochondrial membrane potential, while paraquat‐induced cytochrome c translocation to the nucleus was blocked. The paraquat‐stimulated decline in the cellular energy state, i.e., the ATP/ADP ratio, was prevented in the presence of the Ogg1 activators. Associated with the beneficial effects of the Ogg1 activators described above was the preservation of nuclear area. These data provide evidence of cytoprotection from oxidation of mtDNA when Ogg1 protein is increased or through allosteric activation of the protein, suggesting that the BER pathway may be a target for potential small molecule intervention in COPD.
Support or Funding Information
GlaxoSmithKline