We have used a non-replicating recombinant adenovirus, Ad5MCMVlacZ, which expresses the beta-galactosidase reporter gene, to examine both constitutive and inducible repair of UV-damaged DNA in repair proficient CHO-AA8 Chinese hamster ovary cells and in mutant CHO-UV61 cells which are deficient in the transcription-coupled repair (TCR) pathway of nucleotide excision repair. Host cell reactivation (HCR) of beta-galactosidase activity for UV-irradiated Ad5MCMVlacZ was significantly reduced in non-irradiated CHO-UV61 cells compared to that in non-irradiated CHO-AA8 cells suggesting that repair in the transcribed strand of the UV-damaged reporter gene in untreated cells utilizes TCR. Prior UV-irradiation of cells with low UV fluences resulted in a transient enhancement of HCR for expression of the UV-damaged reporter gene in CHO-AA8 cells but not in TCR deficient CHO-UV61 cells. These results suggest the presence of an inducible DNA pathway in CHO cells that results from an enhancement of TCR or a mechanism that involves the TCR pathway.
We have used a non - replicating recombinant adenovirus , Ad5MCMVlacZ , which expresses the beta - galactosidase reporter gene , to examine both constitutive and inducible repair of UV - damaged DNA in repair proficient CHO - AA8 Chinese hamster ovary cells and in mutant CHO - UV61 cells which are deficient in the transcription - coupled repair ( TCR ) pathway of nucleotide excision repair . Host cell reactivation ( HCR ) of beta - galactosidase activity for UV - irradiated Ad5MCMVlacZ was significantly reduced in non - irradiated CHO - UV61 cells compared to that in non - irradiated CHO - AA8 cells suggesting that repair in the transcribed strand of the UV - damaged reporter gene in untreated cells utilizes TCR . Prior UV - irradiation of cells with low UV fluences resulted in a transient enhancement of HCR for expression of the UV - damaged reporter gene in CHO - AA8 cells but not in TCR deficient CHO - UV61 cells . These results suggest the presence of an inducible DNA pathway in CHO cells that results from an enhancement of TCR or a mechanism that involves the TCR pathway .
Which gene strand is targeted by transcription-coupled repair (TCR)?
Which gene strand is targeted by transcription - coupled repair ( TCR ) ?
the transcribed strand
the transcribed strand