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Modulation of the phosphatase activity of calcineurin by oxidants and antioxidants in vitro
- Sommer, Debbie, Fakata, Keri L., Swanson, Stanley A., Stemmer, Paul M.
- European journal of biochemistry 2000 v.267 no.8 pp. 2312-2322
- in vivo studies, protein-tyrosine kinases, transcription factors, butylated hydroxytoluene, dose response, glutathione, acetylcysteine, lipoic acid, serine, hydrogen peroxide, threonine, butylated hydroxyanisole, tyrosine, oxidants, phospholipases, fibroblasts
- Previous research has indicated that oxidants, antioxidants and the intracellular redox state regulate the activities of a variety of protein tyrosine kinases, protein tyrosine phosphatases, phospholipases and transcription factors. In order to explore the redox regulation of the serine/threonine phosphatase calcineurin, we have investigated the effects of a variety of oxidants and antioxidants on calcineurin phosphatase activity in vitro. The oxidants hydrogen peroxide, superoxide and glutathione disulfide inhibited the phosphatase activity of calcineurin in a doseâdependent manner. Incubation of purified calcineurin with the antioxidants ascorbate, ascorbate 2âphosphate, Î±âlipoic acid, Nâacetylâlâcysteine and glutathione increased phosphatase activity relative to untreated controls. In contrast, several other commonly used antioxidants, including butylated hydroxytoluene, butylated hydroxyanisole, TEMPOL (4âhydroxyâ2,2,6,6âtetramethylpiperidineâNâoxyl), Trolox (6âhydroxyâ2,5,7,8âtetramethylâchromanâ2âcarboxylic acid) and dihydrolipoic acid decreased the activity of purified calcineurin, possibly through prooxidative mechanisms. Although the antioxidant pyrrolidine dithiocarbamate increased the activity of purified calcineurin, it significantly inhibited the activity of calcineurin present in crude fibroblast lysates. These results support and extend the hypothesis that redox factors modulate the phosphatase activity of calcineurin and suggest that further in vivo studies are warranted.