Repair of 8-oxoguanine in DNA is deficient in Cockayne syndrome group B cells

The incision of the 8-oxoguanine in DNA by normal and Cockayne Syndrome (CS ) cell extracts has been investigated. The incision in extracts derived fro m CS cells was similar to 50% of the incision level compared with extracts prepared from normal cells. In contrast, the incision rate of uracil and th ymine glycol was not defective in CS cells. The deficiency in 8-oxoguanine incision was also demonstrated in a CS family. Whereas the proband had mark edly less incision compared with the normal siblings, the parents had inter mediate levels. The low level of 8-oxoguanine-DNA glycosyl;ase in CS extrac ts correlates with the reduced expression of the 8-oxoguanine-DNA glycosyla se gene (hOGG1) in CS cells, Both the levels of expression of the hOGG1 gen e and the incision of 8-oxoguanine in DNA increased markedly after transfec tion of CS-B cells with the CSB gene. We suggest that the CSB mutation lead s to deficient transcription of the hOGG1 gene and thus to deficient repair of 8-oxoguanine in DNA.