OGG1-DNA interactions facilitate NF-κB binding to DNA targets

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Oxidative stress generates DNA lesions like 8-oxoG.
• 8-oxoguanine DNA glycosylase1 (OGG1) repairs these lesions via base excision repair (BER).
• The interplay between DNA repair and gene expression, particularly transcription factor binding, remains incompletely understood.

Purpose of the Study:

• To investigate whether OGG1-mediated DNA repair is compatible with transcription factor binding and gene expression.
• To determine the influence of oxidative DNA lesions and OGG1 on NF-κB binding to the Cxcl2 gene promoter.
• To elucidate the role of OGG1 in NF-κB dependent gene expression.

Main Methods:

• Electrophoretic mobility shift assay (EMSA) was used to assess transcription factor binding.
• Synthetic 8-oxoG lesions were introduced into the Cxcl2 gene promoter sequence.
• Nuclear extracts from TNFα-exposed cells and purified NF-κB were utilized.

Main Results:

• NF-κB DNA occupancy was dependent on OGG1 and the position of 8-oxoG lesions.
• OGG1's interaction with 8-oxoG outside the consensus motif significantly affected NF-κB binding.
• OGG1 was crucial for NF-κB dependent gene expression even before excising 8-oxoG.

Conclusions:

• Pre-excision steps in OGG1-initiated BER facilitate NF-κB DNA binding and subsequent gene expression.
• OGG1 plays a regulatory role in gene expression beyond simple DNA repair.
• These findings highlight a novel mechanism linking oxidative DNA damage repair to transcriptional regulation.