Mitochondrial OGG1 protects against PM2.5-induced oxidative DNA damage in BEAS-2B cells

The enzyme 8-oxoguanine glycosylase 1 (OGG1) has been shown to be involved in the repair of oxidative DNA damage. However, the effect of OGG1 on oxidative DNA damage caused by particulate matter 2.5 (PM2.5) is unknown. Herein, we demonstrated that OGG1 could inhibit the generation of ROS and alleviate mitochondrial dysfunction and increased the expression of IL-1 beta caused by PM2.5. The dichlorodihydrofluorescein diacetate (DCFH-DA) staining and 5,5',6,6'-tetrachloro-1,1',3,3'-. tetraethylbenzi-midazolylcarbocyanine iodide (JC-1) staining using flow cytometry showed that PM2.5 induces the generation of ROS and leads to a reduction in mitochondrial membrane potential (MMP) in BEAS-2B cells. Overexpression of OGG1 inhibited the generation of ROS and the decline in MMP. Knockdown of OGG1 by RNA interference (RNAi) increased the generation of ROS and reduced the MMP. Real-time quantitative PCR (RT-qPCR) for the mitochondrial DNA copy number (mtDNAcn) and flow cytometry for apoptosis revealed that OGG1 inhibits the apoptosis and decreases mtDNAcn induced by PM2.5. Additionally, the results of the comet assay showed that OGG1 had a significant repair effect on DNA strand breaks caused by PM2.5. Overexpression of OGG1 also significantly suppressed the expression of IL-1 beta caused by PM2.5. Together, these data suggest that PM2.5 leads to mitochondrial dysfunction and the up-regulation of IL-1 beta could be reversed by overexpression of OGG1. The mitochondrial dysfunction caused by PM2.5 could be relieved by OGG1. Thus, the base excision repair enzyme OGG1 may alleviate mitochondrial dysfunction caused by PM2.5 involved in the expression of IL-1 beta. (C) 2015 Elsevier Inc. All rights reserved.