Nitric oxide inhibits platelet adhesion to collagen through cGMP-dependent and independent mechanisms: the potential role for S-nitrosylation.
Nitric oxide (NO)-mediated inhibition of platelet function occurs primarily through elevations in cGMP, although cGMP-independent mechanisms such as S-nitrosylation have been suggested as alternative NO-signaling pathways. In the present study we investigated the potential for S-nitrosylation to act as a NO-mediated cGMP-independent signaling mechanism in platelets. The NO-donor, S-nitrosoglutathione (GSNO), induced a concentration-dependent inhibition of platelet adhesion to immobilized collagen. In the presence of the soluble guanylyl cyclase inhibitor, ODQ, NO-mediated activation of the cGMP/protein kinase G signaling pathway was ablated. However, ODQ failed to completely abolish the inhibitory effect of NO on collagen-mediated adhesion, confirming that cGMP-independent signaling events contribute to the regulation of platelet adhesion by NO. Biotin-switch analysis of platelets demonstrated the presence of several S-nitrosylated proteins under basal conditions. Treatment of platelets with exogenous NO-donors, at concentrations that inhibited platelet adhesion, increased the number of S-nitrosylated bands and led to hyper-nitrosylation of basally S-nitrosylated proteins. The extent of S-nitrosylation in response to exogenous NO was unaffected by platelet activation. Importantly, platelet activation in the absence of exogenous NO failed to increase S-nitrosylation beyond basal levels, indicating that platelet-derived NO was unable to induce this type of protein modification. Our data demonstrate that S-nitrosylation of platelet proteins in response to exogenous NO may act as a potentially important cGMP-independent signaling mechanism for controlling platelet adhesion.
Centre for Atherothrombosis Research, University of Bradford, Bradford, UK.
Catherine
C
Irwin
Wayne
W
Roberts
Khalid M
KM
Naseem
D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D003094:Collagen / Q000097:blood*; D006152:Cyclic GMP / Q000097:blood*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000097:blood; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006801:Humans; D015151:Immunoblotting; D009569:Nitric Oxide / Q000097:blood / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000097:blood / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D015539:Platelet Activation / Q000187:drug effects; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests; D011810:Quinoxalines / Q000494:pharmacology; D026422:S-Nitrosoglutathione / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D001798:Blood Proteins; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D011810:Quinoxalines; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D003094:Collagen; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP