Protein disulfide-isomerase mediates delivery of nitric oxide redox derivatives into platelets

• Published in: Biochemical journal 2007-04, Vol.403 (2), p.283-288
• Main Authors: Bell, Susannah E, Shah, Chirag M, Gordge, Michael P
• Format: Article
• Language: English
• Subjects: Amino Acid Transport System L - metabolism; Arsenicals - pharmacology; Bacitracin - pharmacology; Biological Transport; Blood Platelets - drug effects; Blood Platelets - metabolism; Cyclic GMP - metabolism; Enzyme Inhibitors - pharmacology; Glutathione Peroxidase - metabolism; Guanylate Cyclase - metabolism; Humans; Nitric Oxide - analogs & derivatives; Nitric Oxide - metabolism; Oxidation-Reduction; Protein Disulfide-Isomerases - antagonists & inhibitors; Protein Disulfide-Isomerases - metabolism; Receptors, Cytoplasmic and Nuclear - metabolism; Soluble Guanylyl Cyclase
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/BJ20061146

S-nitrosothiol compounds are important mediators of NO signalling and can give rise to various redox derivatives of NO: nitrosonium cation (NO+), nitroxyl anion (NO-) and NO* radical. Several enzymes and transporters have been implicated in the intracellular delivery of NO from S-nitrosothiols. In the present study we have investigated the role of GPx (glutathione peroxidase), the L-AT (L-amino acid transporter) system and PDI (protein disulfide-isomerase) in the delivery of NO redox derivatives into human platelets. Washed human platelets were treated with inhibitors of GPx, L-AT and PDI prior to exposure to donors of NO redox derivatives (S-nitrosoglutathione, Angeli's salt and diethylamine NONOate). Rapid delivery of NO-related signalling into platelets was monitored by cGMP accumulation and DAF-FM (4-amino-5-methylamino-2'7'-difluorofluorescein) fluorescence. All NO redox donors produced both a cGMP response and DAF-FM fluorescence in target platelets. NO delivery was blocked by inhibition of PDI in a dose-dependent manner. In contrast, inhibition of GPx and L-AT had only a minimal effect on NO-related signalling.PDI activity is therefore required for the rapid delivery into platelets of NO-related signals from donors of all NO redox derivatives. GPx and the L-AT system appeared to be unimportant in rapid NO signalling by the compounds used in the present study. This does not, however, exclude a possible role during exposure of cells to other S-nitrosothiol compounds, such as S-nitrosocysteine. These results further highlight the importance of PDI in mediating the action of a wide range of NO-related signals.