Expression and nucleotide excision repair of a UV-irradiated reporter genein unirradiated human cells

It has been suggested that reactivation of damaged reporter genes introduce d into cultured mammalian cells reflects transcription-coupled nucleotide e xcision repair. To evaluate this possibility directly, we introduced a UV-i rradiated shuttle vector, pCMV beta, into unirradiated human cells and comp ared expression of the reporter gene (lacZ) with repair of cyclobutane pyri midine dimers (CPDs). Expression of the irradiated reporter gene was more U V resistant in XPC cells, which are deficient in global genome repair, than in CSB cells, which are deficient in transcription-coupled repair. These r esults are consistent with the idea that repair of the reporter gene is pri marily dependent upon transcription-coupled repair. However, when the plasm id DNA was analyzed for removal of CPDs, no clear evidence was obtained for transcription-coupled repair either in XPC cells or in cells with normal r epair capacity. (C) 1999 Elsevier Science B.V. All rights reserved.