Abstract
DNA strand breaks induced by alkylating agents, oxidants, or ionizing radiation trigger the covalent modification of nuclear proteins with poly(ADP-ribose), which is catalyzed for the most part by poly(ADP-ribose) polymerase-1 and plays a role in DNA base-excision repair. Poly(ADP-ribosyl)ation capacity of mononuclear blood cells correlates positively with life span of mammalian species. Here, we show that l-selegiline, an anti-Parkinson drug with neuroprotective activity and life span-extending effect in laboratory animals, can potentiate γ-radiation-induced poly(ADP-ribose) formation in intact cells. COR4 hamster cells were incubated with l-selegiline (50 nM) for various time periods, followed by γ-irradiation (45 Gy). Quantification of cellular poly(ADP-ribose) levels at 10 min after starting the irradiation revealed significant increases (up to 1.8-fold) in cells preincubated with the drug for 8 h to 7 days compared with drug-free irradiated controls. There was no selegiline-induced change in poly(ADP-ribose) levels of unirradiated cells nor in basal or radiation-induced DNA strand breaks, respectively. Surprisingly, poly(ADP-ribose) polymerase-1 protein was down-regulated by l-selegiline treatment. Addition of l-selegiline to purified poly(ADP-ribose) polymerase-1 did not alter enzymatic activity. In conclusion, the results of the present study identify a novel intervention to potentiate the cellular poly(ADP-ribosyl)ation response. We hypothesize that the effect of l-selegiline is due to modulation of accessory proteins regulating poly(ADP-ribose) polymerase-1 activity and that increased cellular poly- (ADP-ribosyl)ation capacity may contribute to the neuroprotective potential and/or life span extension afforded by l-selegiline.
Footnotes
-
This article is dedicated to Prof. Harald zur Hausen on the occasion of his retirement as Head of the German Cancer Research Center (Deutsches Krebsforschungszentrum), Heidelberg, with gratitude and appreciation for 20 years of leadership.
-
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
-
DOI: 10.1124/jpet.103.051342.
-
ABBREVIATIONS: PARP, poly(ADP-ribose) polymerase; pADPr, poly(ADP-ribose); MAO-B, monoaminooxidase B; TCA, trichloroacetic acid; HPLC, high-performance liquid chromatography; PBS, phosphate-buffered saline; MOPS, 4-morpholinepropanesulfonic acid; FADU, fluorescence-detected alkaline DNA unwinding; TRI, total radioactivity input.
- Received March 6, 2003.
- Accepted May 13, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|