title: Unusual levels of (ADP-ribose)n and DNA synthesis in ataxia telangiectasia cells following gamma-ray irradiation.
abstract: Poly (ADP-ribose) polymerase is a eukaryotic chromosomal enzyme which utilizes the ADP-ribose moiety of NAD to synthesize the nucleic acid homopolymer (ADP-ribose)n (ref. 1). The precise function of (ADP-ribose)n has not been fully established although it does covalently modify chromosomal proteins by ADP-ribosylation. Here we demonstrate that gamma-ray irradiation of lymphoblastoid cells from normal subjects results in depressed DNA synthesis and increased (ADP-ribose)n synthesis. Irradiation of lymphoblastoid cells from patients with the autosomal recessive disease ataxia telangiectasia (AT), however, failed to depress DNA synthesis and did not elevate (ADP-ribose)n levels. We have confirmed that (ADP-ribose)n is synthesized in response to DNA damage and we propose that this polymer may function in the recovery from DNA damage by suppressing DNA synthesis.
mesh_terms: D001260:Ataxia Telangiectasia / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis*; D004260:DNA Repair / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism*; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*
chemical_list: D009702:Nucleoside Diphosphate Sugars; D011064:Poly Adenosine Diphosphate Ribose; D004247:DNA