Study On The Effect Of OGG1 On The Transcriptional Activation Of NF-κB Under Oxidative Stress Condition

Organisms of aerobic respiration is inevitable subjected to be attacked by reactive oxygen species(ROS),When the production of large amounts of ROS exceeds the capacity of the antioxidant system,the body will be in a state of oxidative stress which will inflict oxidative damage on biological macromolecules such as DNA,RNA,lipid,protein and so on.DNA is especially sensitive to reactive oxygen species,and the guanine(G)on DNA is more easily oxidized than other bases to form the oxidative damage marker 8-hydroxyguanine(8-oxoG)which results in the DNA to generate a pair of G:C to a pair of T:A mutation during replication and thus has a high degree of genotoxicity.In order to maintain genomic fidelity and stability,In mammals there are 8-oxoguanine DNA glycosylasel 1(OGG1)can identify and bound 8-oxoG via the base excision repair(BER)pathway to repair 8-oxoG.The genome of 8-oxoG seems to be promptly corrected,but surprisingly,the repair function of OGG1 will be temporarily inactivated in the highly oxidized cell environment,and only when the intracellular redox equilibrium reconstruct,BER function of OGG1 will recover.In addition,Reported in the literature,the formation of 8-oxoG on DNA is not random under oxidative stress condition,GC rich regions(such as the promoter region)which can be used as an oxidation pond and 5 ’end of DNA which comprises a plurality of adjacent guanine sites usually is the preferred target of oxidation.The transcription factor NF-κB is involved in various gene transcription regulation and highly related to the immune response and expression of inflammatory genes.ROS is an important factor affecting NF-κB.Studies on ROS how to control NF-κB activity are focused on that ROS affect NF-κB post-translational modification,but this does not fully explain that ROS induced changing phenomenon of NF-κB transcriptional activity.Our previous studies have demonstrated that OGG1 and NF-κB appear in the same transcription complexes.NF-κB transcriptional activity change that is caused by ROS cannot be completely explained by NF-κB post-translational modification,whether is due to the participation of OGG1? OGG1 which lose BER activity under oxidative stress conditions recognize and combinate 8-oxoG that formate on NF-κB sites or the adjacent promoter region of NF-κB sites,and then adjust the NF-κB activity?In order to study the above problems,We stimulated the cells with proinflammatory cytokines TNF-a to induce a rapid rise of intracellular ROS levels.Furthermore,A series of experiments such as OGG1 interference and chromatin immunoprecipitation were carried out.The experimental results show that TNF-a can successfully induce oxidative stress model under inflammatory conditions.OGG1 was involved in the upregulation of NF-κB driven inflammatory factors expression.Moreover,OGG1 was the same as NF-κB,and was recruited to the inflammatory gene promoter region under oxidative stress conditions.Further,OGG1 interference showed that OGG1 influenced the transcription activation of NF-κB.This study will lay a foundation for revealing the molecular mechanism of the interaction between OGG1 and NF-κB.The potential significance of this study is to provide a useful way to effectively block the interaction between OGG1 and NF-κB as a target in therapy.