Involvement of poly(ADP-ribose) polymerase activity in regulating Chk1-dependent apoptotic cell death.
The activity of poly(ADP-ribose) polymerase (PARP) is highly stimulated following DNA damage resulting in formation of DNA nicks and strand breaks. This leads to modification of numerous proteins, including itself, using NAD(+) as substrate and to exhaustion of intracellular ATP. A highly cytotoxic concentration of the DNA methylating agent methyl methanesulfonate (MMS) results in cellular ATP depletion and cell death primarily by necrosis in both wild-type and DNA polymerase beta null mouse fibroblasts. The loss of ATP can be prevented by the PARP inhibitor 4-amino-1,8-naphthalimide (4-AN), and now cells die by an energy-dependent apoptotic pathway. We find that inhibition of PARP activity transforms a sub-lethal exposure to MMS into a highly cytotoxic event. Under this condition, ATP is not depleted and cell death is by apoptosis. The caspase inhibitor, Z-VAD, shifts the mechanism of cell death to necrosis indicating a caspase-dependent component of the apoptotic cell death. Co-exposure to the Chk1 inhibitor UCN-01 also produces a decrease in apoptotic cell death, but now there is an increase in viable cells and an enhancement in long-term survival. Taken together, our results suggest that inhibition of PARP activity, induced as a result of low dose MMS exposure, signals via a Chk1-dependent pathway for cell death by apoptosis.
Horton
Julie K
JK
Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Stefanick
Donna F
DF
Wilson
Samuel H
SH
D000255:Adenosine Triphosphate / Q000378:metabolism; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D000071877:Checkpoint Kinase 1; D004247:DNA / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D008741:Methyl Methanesulfonate / Q000633:toxicity; D051379:Mice; D009154:Mutation; D009336:Necrosis; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000255:Adenosine Triphosphate; D004247:DNA; D008741:Methyl Methanesulfonate; D011065:Poly(ADP-ribose) Polymerases; D011494:Protein Kinases; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse