A dual approach in the study of poly (ADP-ribose) polymerase: In vitro random mutagenesis and generation of deficient mice

A dual approach to the study of poly (ADP-ribose)polymerase (PARP) in terms of its structure and function has been developed in our laboratory. Random mutagenesis of the DNA binding domain and catalytic domain of the human PA RP, has allowed us to identify residues that are crucial for its enzymatic activity. In parallel PARP knock-out mice were generated by inactivation of both alle les by gene targeting. We showed that: (i) they are exquisitely sensitive t o gamma-irradiation, (ii) they died rapidly from acute radiation toxicity t o the small intestine, (iii) they displayed a high genomic instability to g amma-irradiation and MNU injection and, (iv) bone marrow cells rapidly unde rwent apoptosis following MNU treatment, demonstrating that PARP is a survi val factor playing an essential and positive role during DNA damage recover y and survival.