Poly(ADP-ribose) polymerase, a major determinant of early cell response to ionizing radiation.
OBJECTIVE
To determine whether DNA-dependent protein kinase (DNA-PK) and poly(ADP-ribose) polymerase (PARP-1) are involved in eliciting the rapid fluctuations of radiosensitivity that have been observed when cells are exposed to short pulses of ionizing radiation.


METHODS
The effect of DNA-PK and PARP-1 inhibitors on the survival of cells to split-dose irradiation was investigated using Chinese hamster V79 fibroblasts and human carcinoma SQ-20B cells. The responses of PARP-1 proficient and PARP-1 knockout mouse 3T3 fibroblasts were compared in a similar split-dose assay.


RESULTS
Inactivation of DNA-PK by wortmannin potentiated radiation-induced cell kill but it did not alter the oscillatory, W-shaped pattern of early radiation response. In contrast, oscillatory radiation response was abolished by 3-aminobenzamide, a reversible inhibitor of enzymes containing a PARP catalytic domain. The oscillatory response was also lacking in PARP-1 knockout mouse 3T3 fibroblasts.


CONCLUSIONS
The results show that PARP-1 plays a key role in the earliest steps of cell response to ionizing radiation with clonogenic ability or growth as endpoint. It is hypothesized that rapid poly(ADP-ribosylation) of target proteins, or recruitment of repair proteins by activated PARP-1 at the sites of DNA damage, bring about rapid chromatin remodelling that may affect the incidence of chromosomal damage upon re-irradiation.
Fernet
M
M
Unité 350 INSERM, Institut Curie-Recherche, Orsay, France.
Ponette
V
V
Deniaud-Alexandre
E
E
Ménissier-De Murcia
J
J
De Murcia
G
G
Giocanti
N
N
Megnin-Chanet
F
F
Favaudon
V
V
D016475:3T3 Cells; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D020134:Catalytic Domain / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D002843:Chromatin / Q000528:radiation effects; D006224:Cricetinae; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004307:Dose-Response Relationship, Radiation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000528:radiation effects; D005720:Gamma Rays / Q000009:adverse effects; D006801:Humans; D051379:Mice; D009687:Nuclear Proteins; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011839:Radiation, Ionizing; D013997:Time Factors; D014407:Tumor Cells, Cultured; D000077191:Wortmannin
D000730:Androstadienes; D001549:Benzamides; D002843:Chromatin; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; C025160:3-aminobenzamide; D011065:Poly(ADP-ribose) Polymerases; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D000077191:Wortmannin