The Study On The Mechanism Of The Interaction Between DNA Damage Repair Enyme OGG1 And Transcription Factors NF-κB

Organisms are constantly challenged from the external environment and the aerobic respiration.Those conditions induced the form of a series of compound include the hydrogen peroxide（H₂O₂）,and hydroxyl radicals（OH）,superoxide anion（O2-）in the aerobic respiration of organism.All the products are called reactive oxygen species（ROS）.Low levels of ROS maintain a healthy immune system.However,high levels of ROS induce damage to cellular molecules,including DNA,protein and lipids.Since the nucleic acid is the carrier of genetic information,the study on DNA oxidative damage has an important significance.When DNA were damaged by ROS,8-oxoG-7,8-dihydroguanine（8-oxoG）is one of the most abundant because of guanine’s lowest redox potential among DNA bases.8-oxoG can caused base mismatch.In mammalian evolve a set of mechanisms that can identify aberrant base.8-oxoG is repaired by the 8-oxoguanine DNA glycosybase-1（OGG1）.Under the oxidative stress state,nuclear transcription factors NF-κB can regulate the expression of diverse oxygen reduction reaction gene,mostly it can bind the conservative region contain three continuous G.We guess OGG1can interact with NF-κB by adjust its dimer to conservative sequence.The previous date show,in the circumstances of oxidative stress,increased the8-oxoG level in DNA,recruited OGG1 to promoter sequences sand transiently inhibited BER of 8-oxoG.Then recruits Specific Protein 1（Sp1）,transcription Initiation Factor II-D（TFIID）,and phosphor-RNA polymerase II,resulting in the rapid expression of cytokines and inflammatory cell.To study the structure mechanism of OGG1 bind to NF-κB.We establish the model of oxidative stress under the condition of TNF-a induced inflammatory responses.Initially,through Western Blot we detect the expression of NF-κB in different cell.To exploring which structural domain of OGG1 can interact with Rel-A（p65）and p50,We construct different section of OGG1,through GST-pull-down to explore which domain of OGG1 can bind to the dimer of Rel-A（p65）and p50.Our studies show:Large amount of NF-κB protein expression in HEK293、A549 and Raw cell.Under the exposure of TNF-a stimulated 30 min,the subunit of Rel-A（p65）and p50 can obviously entrance nuclear,and bind OGG1combine compound.Through GST-pull-down,our results show the amino acid from 180 to262 and 167 to 345 can bind to Rel-A（p65）and p50.Our experiment illuminate the mechanism of OGG1 and NF-κB,Laying foundations for the next structural domain of OGG1.Provide the basis for the small-molecule inhibitor,in order to intentionally block proinflammatory gene transcription activation,improve the innate immune disorders by chronic inflammation and acute inflammation.It has the important significance of translational medicine.