A critical role for extracellular protein disulfide isomerase during thrombus formation in mice

Abstract

Thiol isomerases, including protein disulfide isomerase (PDI), catalyze disulfide oxidation, reduction, and isomerization, thereby playing an important role in protein synthesis. To determine whether extracellular PDI mediates thrombus formation in an animal model, PDI expression, platelet accumulation, and fibrin generation were monitored in the blood vessels of mice by intravital fluorescence microscopy following laser-induced arteriolar injury. A time-dependent increase in PDI was observed in murine thrombi following injury. Infusion of the PDI inhibitor bacitracin or a blocking monoclonal antibody against PDI inhibited platelet thrombus formation and fibrin generation. Fibrin deposition is normal in mice lacking the G protein-coupled platelet receptor Par4, although there is no stable accumulation of platelets. Infusion of monoclonal antibodies against PDI into the circulation of Par4 -/-mice prior to vessel wall injury inhibited fibrin generation. These results indicate that PDI is required in vivo in mice for both fibrin generation and platelet thrombus formation.

The protein disulfide isomerase AGR2 is essential for production of intestinal mucus

“…The molecular mechanisms of these effects have not been clearly identified, but in light of the work presented here may involve alterations in the processing of cysteine-containing secreted or cell surface proteins expressed by those cells. Other recent studies suggest roles for the archetypical mammalian PDI (P4HB) in neurodegenerative diseases (37) and in thrombus formation (38,39). Improved understanding of the specific roles of individual mammalian PDIs may therefore provide important new clues about disease pathogenesis and susceptibility.…”

Inhibition of thiol isomerase activity diminishes endothelial activation of plasminogen, but not of protein C

“…More recently it has become clear that a range of thiol isomerase enzymes (including PDI, ERp57 and ERp5) become available at the platelet surface following activation [6]. Experiments using mouse models of thrombus formation have highlighted a critical role for PDI [7][8][9], or its close homologue ERp57 (10), in platelet accumulation and fibrin deposition [11] . PDI associates with tissue factor and targets the allosteric cys186-cys209 disulphide bond [12].…”

“…Endothelial cells in culture also express PDI on their exofacial surface, and this PDI regulates the adhesive properties of both thrombospondin [17] and of its binding partner integrin αV β3 [18]. In contrast, experiments performed using mouse models of thrombus formation indicate that, in vivo, PDI is not expressed on the surface of unperturbed vessel wall, but that it accumulates rapidly following vascular injury by binding to β3 integrins [7,8,19].…”

Rutin- potent natural thrombolytic agent

“…Platelets are a rich source of extracellular PDI, expressing this protein on their surface and also secreting PDI in response to thrombin stimulation (Burgess et al, 2000;Cho et al, 2008). Endothelial cells also express PDI upon agonist stimulation or …”

“… Agents like Juniferdin or Bacitracin which also inhibit PDI function and thus inhibit thrombus formation in vivo (Khan et al, 2011;Dickerhof et al, 2011;Cho et al, 2008) and are either cytotoxic or non-selective (Karala and Ruddock, 2010;Khan et al, 2011). When compared with these agents, rutin demonstrated selectivity towards extra-cellular PDI and is relatively non-toxic.…”