RESTORATION OF X-RAY RESISTANCE AND V(D)J RECOMBINATION IN MUTANT-CELLS BY KU CDNA

Three genetic complementation groups of rodent cells are defective for both repair of x-ray-induced double-strand breaks and V(D)J recombina tion. Cells from one group lack a DNA end-binding activity that is bio chemically and antigenically similar to the Ku autoantigen. Transfecti on of complementary DNA (cDNA) that encoded the 86-kilodalton subunit of Ku rescued these mutant cells for DNA end-binding activity, x-ray r esistance, and V(D)J recombination activity. These results establish a role for Ku in DNA repair and recombination. Furthermore, as a compon ent of a DNA-dependent protein kinase, Ku may initiate a signaling pat hway induced by DNA damage.