IMPAIRED REPAIR OF UVC‐INDUCED DNA DAMAGE IN L5178Y‐R CELLS: DNA UNWINDING STUDIES WITH THE USE OF 1‐β‐D‐ARABINOFURANOSYL CYTOSINE

We examined the response of chromatin to increasing NaCl and MgCl2 concentrations in UVC-irradiated L5178Y (LY) R and S cells, using the spectral index method (Dixon and Burkholder 1985). We have found an alteration in chromatin properties 1 h after UVC-irradiation of repair proficient LY-S cells, but no change in repair deficient LY-R cells. The change was shown as lowered spectral index, indicating that at given Na+ and Mg++ concentrations (1 or 200 mM NaCl, 0 or 0.5 mM MgCl2) chromatin from UVC-irradiated LY-S cells was more compact than that from unirradiated ones. Benzamide treatment reversed the effect of UVC-irradiation in LY-S cells and did not change the response pattern of chromatin from LY-R cells or unirradiated LY-S cells.

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Adaptive changes in NAD+ metabolism in ultraviolet light-irradiated murine lymphoma cells

Kleczkowska

Szumiel

Althaus

1990

Cell Biol Toxicol

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We have determined the ability of UV254nm-irradiated murine lymphoma cells to adapt their NAD+ metabolism to the increased NAD+ consumption for the poly ADP-ribosylation of chromatin proteins. Two murine lymphoma sublines with differential UV-sensitivity and poly(ADP-ribose) turnover were used as a model system. The first subline, designated LY-R is UV254nm-sensitive and tumorigenic in DBA/2 mice. The second subline, LY-S is UV254nm-resistant and nontumorigenic. Following treatment of these cells with 2 mM benzamide, an inhibitor of the NAD(+)-utilizing enzyme poly(ADP-ribose) polymerase, NAD+ levels slowly increased up to about 160% of control levels after 3 hours. When benzamide was added to these cultures 20 min after UV254nm irradiation, a dramatic transient increase of NAD+ levels was observed within 4 min in LY-R cells and more moderately in LY-S cells. At later times after UV254nm irradiation, the NAD+ levels increased in both sublines reaching up to 200% of the concentrations prior to benzamide treatment. These results demonstrate an adaptative response of NAD+ metabolism to UV254nm irradiation. In parallel, we observed a differential repartitioning of ADP-ribosyl residues between the NAD+ and poly(ADP-ribose) pools of LY-R and LY-S cells that correlates with the differential UV sensitivity of these cells.

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IMPAIRED REPAIR OF UVC‐INDUCED DNA DAMAGE IN L5178Y‐R CELLS: DNA UNWINDING STUDIES WITH THE USE OF 1‐β‐D‐ARABINOFURANOSYL CYTOSINE

Cited by 23 publications

References 21 publications

Differential Effect of Benzamide on Repair-Deficient and Proficient Strains of L5178Y Lymphoblasts Exposed to UVC or X-Radiations

Differential Effect of Benzamide on Repair-Deficient and Proficient Strains of L5178Y Lymphoblasts Exposed to UVC or X-Radiations

Benzamide-inhibitable alterations in spectral properties of chromatin accompany DNA repair in UVC-exposed L5178Y cells

Adaptive changes in NAD+ metabolism in ultraviolet light-irradiated murine lymphoma cells

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