Poly ADP-ribosylation in two L5178Y murine lymphoma sublines differentially sensitive to DNA-damaging agents.
OBJECTIVE
To characterize the response to X-irradiation of the poly ADP-ribosylation system in two closely related murine lymphoma sublines, L5178Y-R (LY-R) and L5178Y-S (LY-S), with differential sensitivity to various DNA damaging agents (UV-C and ionizing radiation, hydrogen peroxide).


METHODS
LY cells were X-irradiated (2 Gy). NAD+ was determined in cell extracts by high-pressure liquid chromatography. ADP-ribose polymers were purified and analysed by densitometry after polyacrylamide gel electrophoresis. Nuclear matrix proteins were separated by SDS-polyacrylamide gel electrophoresis and processed for ADP-ribose polymer blots to estimate their ability to bind poly(ADP-ribose).


RESULTS
In the radiosensitive LY-S cells, the constitutive levels of ADP-ribose polymers were twofold higher than in radioresistant LY-R cells, but unresponsive to a challenge with 2 Gy X-rays. The concentrations of NAD+ - the substrate for poly(ADP-ribose) synthesis - were identical in the two cell lines. X-rays (2 Gy) depleted NAD+ only in LY-S cells. These cells also produced shorter poly(ADP-ribose) molecules as compared with LY-R cells. Nuclear matrix preparations of LY-S cells exhibited lower poly(ADP-ribose)-binding capacity than those of LY-R cells.


CONCLUSIONS
The results demonstrate disturbances in the poly ADP-ribosylation response of the radiosensitive LY-S cells and reduced poly(ADP-ribose)-binding affinity of the nuclear matrix of these cells.
Kleczkowska
H E
HE
Institute of Pharmacology and Toxicology, University of Zürich-Tierspital, Zurich, Switzerland.
Malanga
M
M
Szumiel
I
I
Althaus
F R
FR
D000818:Animals; D004249:DNA Damage; D004260:DNA Repair; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007940:Leukemia L5178 / Q000378:metabolism* / Q000532:radiotherapy*; D051379:Mice; D009243:NAD / Q000378:metabolism / Q000528:radiation effects; D015530:Nuclear Matrix / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism* / Q000528:radiation effects*; D011836:Radiation Tolerance; D015398:Signal Transduction / Q000528:radiation effects; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
D009243:NAD; D011064:Poly Adenosine Diphosphate Ribose; D006861:Hydrogen Peroxide