Protein disulfide-isomerase mediates delivery of nitric oxide redox derivatives into platelets.
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.
Bell
Susannah E
SE
Department of Biomedical Science, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
Shah
Chirag M
CM
Gordge
Michael P
MP
D027062:Amino Acid Transport System L / Q000378:metabolism; D001152:Arsenicals / Q000494:pharmacology; D001414:Bacitracin / Q000494:pharmacology; D001692:Biological Transport; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005979:Glutathione Peroxidase / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D009569:Nitric Oxide / Q000031:analogs & derivatives / Q000378:metabolism*; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D000071756:Soluble Guanylyl Cyclase
D027062:Amino Acid Transport System L; D001152:Arsenicals; D004791:Enzyme Inhibitors; D018160:Receptors, Cytoplasmic and Nuclear; C029341:oxophenylarsine; D001414:Bacitracin; D009569:Nitric Oxide; D005979:Glutathione Peroxidase; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D019704:Protein Disulfide-Isomerases; D006152:Cyclic GMP