Poly(ADP-ribose) polymerase activity is not affected in ataxia telangiectasia cells and knockout mice

Poly(ADP-ribose) polymerase (PARP) is a constitutive factor of the DNA dama ge surveillance network in dividing cells, Based on its capacity to bind to DNA strand breaks, PARP plays a regulatory role in their resolution in viv o. ATM belongs to a large family of proteins involved in cell cycle progres sion and checkpoints in response to DNA damage. Both proteins may act as se nsors of DNA damage to induce multiple signalling pathways leading to activ ation of cell cycle checkpoints and DNA repair. To determine a possible rel ationship between PARP and ATM, we examined the PARP response in an ATM-nul l background. We demonstrated that ATM deficiency does not affect PARP acti vity in human cell lines or Atm-deficient mouse tissues, nor does it alter PARP activity induced by oxidative damage or gamma-irradiation, Our results support a model in which PARP and ATM could be involved in distinct pathwa ys, both effecters transducing the damage signal to cell cycle regulators.