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Townsend DM , Findlay VJ , Fazilev F , Ogle M , Fraser J , Saavedra JE , Ji XH , Keefer LK , Tew KD
A glutathione S-transferase pi-activated prodrug causes kinase activation concurrent with S-glutathionylation of proteins
Molecular Pharmacology. 2006 Feb;69(2) :501-508
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Nitric oxide (NO) is an endogenous, diffusible, transcellular messenger shown to affect regulatory and signaling pathways with impact on cell survival. Exposure to NO can impart direct post-translational modifications on target proteins such as nitration and/or nitrosylation. As an alternative, after interaction with oxygen, superoxide, glutathione, or certain metals, NO can lead to S-glutathionylation, a post-translational modification potentially critical to signaling pathways. A novel glutathione S-transferase pi (GST pi)-activated pro-drug, O-2-{2,4-dinitro-5[4-(N-methylamino)benzoyloxy]phenyl} 1-(N,N-dimethylamino)diazen-1-ium-1,2-diolate (PABA/NO), liberates NO and elicits toxicity in vitro and in vivo. We now show that PABA/NO induces nitrosative stress, resulting in undetectable nitrosylation, limited nitration, and high levels of S-glutathionylation. After a single pharmacologically relevant dose of PABA/NO, S-glutathionylation occurs rapidly (< 5 min) and is sustai ned for similar to 7 h, implying a half-life for the deglutathionylation process of approximately 3 h. Two-dimensional SDS-polyacrylamide gel electrophoresis and immunoblotting with a monoclonal antibody to S-glutathionylated residues indicated that numerous proteins were S-glutathionylated. Subsequent matrix-assisted laser desorption ionization/time of flight analysis identified 10 proteins, including beta-lactate dehydrogenase, Rho GDP dissociation inhibitor beta, ATP synthase, elongation factor 2, protein disulfide isomerase, nucleophosmin-1, chaperonin, actin, protein tyrosine phosphatase 1B (PTP1B), and glucosidase II. In addition, we showed that sustained S-glutathionylation was temporally concurrent with drug-induced activation of the stress kinases, known to be linked with cell death pathways. This is consistent with the fact that PABA/NO induces S-glutathionylation and inactivation of PTP1B, one phosphatase that can participate in deactivation of kinases. These eff ects were consistent with the presence of intracellular PABA/NO or met abolites, because cells overexpressing MRP1 were less sensitive to the drug and had reduced levels of S-glutathionylated proteins.
English Article