OGG1 Inhibitor TH5487 Alters OGG1 Chromatin Dynamics and Prevents Incisions.

Bishoy M F Hanna,Oliver Mortusewicz,Thomas Helleday

doi:10.3390/biom10111483

Abstract

8-oxoguanine DNA glycosylase (OGG1) is the main DNA glycosylase responsible for the excision of 7,8-dihydro-8-oxoguanine (8-oxoG) from duplex DNA to initiate base excision repair. This glycosylase activity is relevant in many pathological conditions including cancer, inflammation, and neurodegenerative diseases. To have a better understanding of the role of OGG1, we previously reported TH5487, a potent active site inhibitor of OGG1. Here, we further investigate the consequences of inhibiting OGG1 with TH5487. TH5487 treatment induces accumulation of genomic 8-oxoG lesions. Furthermore, it impairs the chromatin binding of OGG1 and results in lower recruitment of OGG1 to regions of DNA damage. Inhibiting OGG1 with TH5487 interferes with OGG1′s incision activity, resulting in fewer DNA double-strand breaks in cells exposed to oxidative stress. This study validates TH5487 as a potent OGG1 inhibitor that prevents the repair of 8-oxoG and alters OGG1–chromatin dynamics and OGG1′s recruitment kinetics.

Highlights

Reactive oxygen species (ROS) can be generated from a number of endogenous or exogenous sources
Our results indicate that TH5487 inhibits OGG1, preventing the repair of 8-oxoG, and alters OGG1–chromatin dynamics and OGG1 s recruitment kinetics
U2OS cells were cultured at 37 ◦C in a 5% CO2 atmosphere in Dulbecco’s Modified Eagle Medium (DMEM; Gibco) supplemented with 10% of fetal bovine serum (FBS; Gibco) and 100 U/mL penicillin–streptomycin (Gibco)

Summary

Introduction

Reactive oxygen species (ROS) can be generated from a number of endogenous or exogenous sources. Generated ROS are a by-product of normal oxygen metabolism in different organelles including mitochondria, peroxisomes, and the endoplasmic reticulum. Exposure to ionizing radiation or some chemicals are among the exogenous sources of ROS [1]. When maintained at appropriate cellular concentrations, ROS are involved in several physiological processes such as signaling pathways and immune responses [3,7]. At higher concentrations, ROS can overwhelm the cellular antioxidant capacity, generating oxidative stress and causing oxidative damage to lipids, proteins and DNA [1,3,4]

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