Ogg1

8-hydroxyguanine, a form of oxidative DNA damage induced by free radicals, causes G:C to T:A transversion. In E. coli, three DNA repair enzymes exist to prevent the mutagenic effects of 8-hydroxyguanine. One of these enzymes, MutM, was found to have a functional yeast (yOgg1) and human (hOgg1) homologue. hOgg1 proteins efficiently release the 8-hydroxyguanine opposite the pyrimidine from DNA and cleave the AP site in a manner similar to bacterial and yeast enzymes. Genetic backgrounds in control of the repair of damaged DNA are involved in the susceptibility to cancer development. The hOgg1 gene has been mapped to region 3p26.2, a region showing loss of heterozygosity (LOH) in a variety of cancers. In particular, 3p25-p26 is a common LOH region in lung cancer. Recent work has demonstrated that Ogg plays an important role in CAG expansion, a characteristic of several neurodegenerative diseases. Ogg appears to be responsible for progressive expansion of poly-Q tracts in response to oxidative damage. Thus, Ogg provides a direct link between DNA damage and toxicity in neurons. 

Image: Ogg1 satining of formaldehyde fixed frozen sections of the substantia nigra from a Rhesus macaque (Macaca mulatta). Photo courtesy of Glen Kisby, Oregon Health Sciences University. 

1, 5, 10 ng titration of human recombinant Ogg1 protein, detected by Ogg1 antibody.