Function of poly(ADP-ribose) polymerase in response to DNA damage: gene-disruption study in mice.
To elucidate the biological functions of poly(ADP-ribose) polymerase (PARP, [EC 2.4.2.30]) in DNA damage responses, genetic and biochemical approaches were undertaken. By disrupting exon 1 of the mouse PARP gene by a homologous recombination, PARP-deficient mouse embryonic stem (ES) cell lines and mice could be produced without demonstrating lethality. PARP-/- ES cells showed complete loss of PARP activity and increased sensitivity to gamma-irradiation and an alkylating agents, indicating a physiological role for PARP in the response to DNA damage. p53, a key molecule in cellular DNA damage response, was found to stimulate PARP activity and became poly(ADP-ribosyl)ated in the presence of damaged DNA. However, PARP-/- ES cells showed p21 and Mdm-2 mRNA induction following gamma-irradiation, indicating that PARP activity is not indispensable for p21 and Mdm-2 mRNA induction in the established p53-cascade. On the other hand, in a reconstituted reaction system, purified PARP from human placenta suppressed the pRB-phosphorylation activity in the presence of NAD and damaged DNA. Human PARP expressed in E. coli showed a similar effect on pRB-phosphorylation activity of cdk2. These findings suggest a direct involvement of PARP in the regulation of cdk activity for cell-cycle arrest.
Masutani
M
M
Biochemistry Division, National Cancer Center Research Institute, Tokyo, Japan.
Nozaki
T
T
Nishiyama
E
E
Shimokawa
T
T
Tachi
Y
Y
Suzuki
H
H
Nakagama
H
H
Wakabayashi
K
K
Sugimura
T
T
D000818:Animals; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008954:Models, Biological; D016254:Mutagenesis, Insertional; D010920:Placenta / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D016159:Tumor Suppressor Protein p53; D011065:Poly(ADP-ribose) Polymerases; D018844:Cyclin-Dependent Kinases