Acceptor proteins for poly(ADP-ribose) in irradiated normal human and ataxia telangiectasia (AT) fibroblasts

Poly(ADP-ribose) polymerase activity is stimulated by DNA strand breaks and may participate in DNA repair. Since treatment of cells with DNA damaging agents stimulated the poly(ADP-ribosylation) of a specific set of proteins, the authors have analyzed the acceptors in irradiated human fibroblasts from normal individuals and from patients with AT, a disease associated with a hypersensitivity to ionizing radiation. Cells were permeabilized and incubated with /sup 32/P-NAD, proteins were separated by polyacrylamide gel electrophoresis, and the poly (ADP-ribose) acceptors were detected by autoradiography. In all four strains, the major acceptor was the 116 kd auto-modified polymerase, while other prominent radioactive bands were at 2, 45, and 60 kd. Labeling of these bands was increased following irradiation of the cells with 3-30 Gy. Of interest was the detection of a poly (ADP-ribosylated) protein at 19 kd in the two normal strains but not in either AT strain. The results suggest that a defect in the ADP-ribosylation of the 19 kd protein is associated with AT and possible with the hypersensitivity of AT cells to ionizing radiation