The Key Involvement of Poly(ADP-Ribosylation) in Defense Against Toxic Agents: Molecular Biology Studies

PolyADP-ribose polymerase PADPRP is a chromatin-bound enzyme which is pivotal in cellular recovery from DNA strand break damage. PADPRP requires DNA for activity it is significant that the catalytic activity of this enzyme is directly coordinated with the number of DNA strand breaks in DNA, both in vitro as well as in vivo. Thus, polyADP-ribosylation is rapidly modulated in response to environmentally significant DNA-damaging agents this probably represents the most initial response of the cell to genotoxic damage to the genome. One of the major aims over the past few years of this project has been to establish and characterize cells stably transfected with PADPRP antisense CDNA under the control of an inducible promoter and to establish conditions under which significant depletion of nuclear PADPRP could be achieved. This approach has been particularly successful in assessing the potential roles of polyADP-ribosylation in a variety of biological processes, all involving DNA strand breaks, without the use of non-specific chemical inhibitors. Thus, we have assigned biochemical roles for PADPRP in the recovery of cells with exposure to mutagenic agents, gene amplification and DNA replication.