POLY(ADP-RIBOSE) MOLECULES FORMED DURING DNA-REPAIR IN-VIVO

We have found that human cells respond to treatment with an alkylating carcinogen by producing a specific, highly conserved array of poly(AD P-ribose) molecules. Using in situ radiolabeling and boronate affinity chromatography, we have been able to isolate ADP-ribose polymers from living cells and to quantify individual molecular size classes on hig h resolution polyacrylamide gels. Despite carcinogen-induced changes i n poly(ADP-ribose) turnover, the relative frequency of linear polymers was strictly conserved. However, the abundance of branched polymers w ith high affinity for histones increased 2.6-fold. These polymers mere degraded more slowly than linear polymers. Our results indicate that the poly(ADP-ribose) molecules involved in the shuttling of histones o n DNA in vitro also play a role in the repair of DNA damage in vivo.