RECRUITMENT OF DAMAGED DNA TO THE NUCLEAR MATRIX IN HAMSTER-CELLS FOLLOWING ULTRAVIOLET-IRRADIATION

We examined the relationship between the nuclear matrix and DNA in the dihydrofolate reductase domain following irradiation of Chinese hamst er cells with UV light. The fraction of matrix-bound DNA increased in transcribed and non-transcribed regions during a 3 h period after irra diation. However, no increase was observed with excision repair-defici ent cells mutant for the ERCC1 gene. The major UV-induced lesion, the cyclobutane pyrimidine dimer, increased in frequency in the matrix-bou nd DNA 1 h after irradiation, in both transcribed and nan-transcribed regions, but decreased subsequently. This phenomenon was also lacking in excision repair-deficient cells. These data demonstrate that recrui tment of lesion-containing DNA to the nuclear matrix occurs following UV irradiation and suggest that this recruitment is dependent upon nuc leotide excision repair. This is consistent with the concept of a 'rep air factory' residing on the nuclear matrix at which excision repair o ccurs.