DNA-REPAIR FINE-STRUCTURE IN WERNERS-SYNDROME CELL-LINES

Werner's syndrome (WS) is a human segmental progerioid disorder with a n autosomal recessive pattern of inheritance. Patients with WS exhibit a number of symptoms resembling a premature aging phenotype. We have examined the fine structure of the DNA repair of UV-induced cyclobutan e pyrimidine dimers in Epstein-Barr virus (EBV)-transformed WS lymphob lastoid cell lines and in a primary WS fibroblast cell line. The repai r was measured at the level of the gene and also in the general genome . Gene-specific and strand-specific DNA repair was measured in the act ively transcribed genes dihydrofolate reductase (DRFR), c-myc, and p53 , and in the transcriptionally inactive regions, delta globin and the X-linked 754 domain. Both gene-specific repair and strand-specific rep air were deficient in the transformed WS lymphoblastoid cell lines com pared to normal controls. In normal cells, repair in the transcribed s trand was 25 (4 h), 43 (8 h), and 72% (24 h); in the WS cells on avera ge, repair in the transcribed strand was 18 (4 h), 27 (8 h), and 44% ( 24 h). However, in the primary WS fibroblast cell line, we found a pat tern of preferential gene repair which was similar to that in normal h uman cells, In contrast to cells from patients with the gene-specific repair deficient disease Cockayne's syndrome, which show greatly delay ed RNA synthesis recovery after UV irradiation, the WS cells had norma l recovery of RNA synthesis. The DNA repair results differ for the dif ferent cell types, and our findings thus do not establish a general DN A repair phenotype for WS cells. The fibroblasts had proficient repair , but in the WS lymphoblasts we find a deficiency in DNA repair which could contribute to the reported hypermutability in these cells. The l ymphoblasts are, however, transformed cells, and it raises the concern that biological findings in transformed cells may not reflect the sit uation in primary cells. (C) 1996 Academic Press, Inc.