DNA excision repair and DNA damage-induced apoptosis are linked to Poly(ADP-ribosyl)ation but have different requirements for p53.
Poly(ADP-ribose) polymerase (PARP) is a DNA binding zinc finger protein that catalyzes the transfer of ADP-ribose residues from NAD(+) to itself and different chromatin constituents, forming branched ADP-ribose polymers. The enzymatic activity of PARP is induced upon DNA damage and the PARP protein is cleaved during apoptosis, which suggested a role of PARP in DNA repair and DNA damage-induced cell death. We have generated transgenic mice that lack PARP activity in thymocytes owing to the targeted expression of a dominant negative form of PARP. In the presence of single-strand DNA breaks, the absence of PARP activity correlated with a strongly increased rate of apoptosis compared to cells with intact PARP activity. We found that blockage of PARP activity leads to a drastic increase of p53 expression and activity after DNA damage and correlates with an accelerated onset of Bax expression. DNA repair is almost completely blocked in PARP-deficient thymocytes regardless of p53 status. We found the same increased susceptibility to apoptosis in PARP null mice, a similar inhibition of DNA repair kinetics, and the same upregulation of p53 in response to DNA damage. Thus, based on two different experimental in vivo models, we identify a direct, p53-independent, functional connection between poly(ADP-ribosyl)ation and the DNA excision repair machinery. Furthermore, we propose a p53-dependent link between PARP activity and DNA damage-induced cell death.
Beneke
R
R
Institut für Zellbiologie (Tumorforschung), IFZ, Germany.
Geisen
C
C
Zevnik
B
B
Bauch
T
T
Müller
W U
WU
Küpper
J H
JH
Möröy
T
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D004249:DNA Damage; D004260:DNA Repair; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
D016159:Tumor Suppressor Protein p53; D011064:Poly Adenosine Diphosphate Ribose; D011065:Poly(ADP-ribose) Polymerases