Overexpression of human OGG1 improves skeletal muscle endurance in mice

Abstract

8‐oxoguanine glycosylase 1 (OGG1) is a DNA glycosylase that catalyzes the excision of oxidized guanines as part of the base excision repair (BER) DNA repair pathway. While OGG1 has been studied extensively for its role in tumor prevention and neurodegeneration, recent studies have indicated a novel role for this enzyme in maintaining metabolic health. In particular, deletion of OGG1 increased propensity to diet‐ and age‐induced obesity, as well as impaired skeletal muscle dysfunction. In contrast, overexpression of human OGG1 (hOGG1) significantly protected mice from diet‐induced obesity and related metabolic sequelae. Unbiased transcriptomics studies using mice constitutively overexpression OGG1 (Ogg1‐transgenic ‐Ogg1Tg) revealed significant transcriptional changes in skeletal muscle of these mice. Among the most highly induced genes, expression of the myokine fibroblast growth factor‐21(FGF21) was elevated by 9.9 fold in RNA‐Seq analyses. qPCR analysis further confirmed these changes in skeletal muscle without any alterations in the hepatic or cardiac expression of Fgf21. Commensurate with gene expression changes, plasma FGF21 was elevated by 11.2 fold in Ogg1Tg mice relative to WT controls. Conversely, Fgf21 gene expression in skeletal muscle and plasma FGF21 levels were decreased by 25 and 29% respectively in Ogg1‐/‐ mice. Consistent with increased FGF21 activity, phosphorylation of AMPK and its target acetyl CoA carboxylase (ACC), and Ser/Thr phosphorylation of Akt were significantly increased in Ogg1Tg muscle. FGF21 is known to increase expression of PGC‐1α protein. Consistently, Ogg1Tg mice had a 1.6 fold increase in PGC‐1α protein. Given these alterations, we asked if markers of muscle health such as endurance would be altered in Ogg1Tg mice. Interestingly, Ogg1Tg mice displayed a 3.4 fold increase in running capacity, consistent with improved skeletal muscle health in these animals. This improvement in exercise capacity was evident in both young and aged mice and have important implications to the management of age‐related declines in muscle health and DNA repair capacity.