| First Author | Li J | Year | 2019 |
| Journal | Circulation | Volume | 139 |
| Issue | 10 | Pages | 1300-1319 |
| PubMed ID | 30586735 | Mgi Jnum | J:339793 |
| Mgi Id | MGI:6363865 | Doi | 10.1161/CIRCULATIONAHA.118.036323 |
| Citation | Li J, et al. (2019) Platelet Protein Disulfide Isomerase Promotes Glycoprotein Ibalpha-Mediated Platelet-Neutrophil Interactions Under Thromboinflammatory Conditions. Circulation 139(10):1300-1319 |
| abstractText | BACKGROUND: Platelet-neutrophil interactions contribute to vascular occlusion and tissue damage in thromboinflammatory disease. Platelet glycoprotein Ibalpha (GPIbalpha), a key receptor for the cell-cell interaction, is believed to be constitutively active for ligand binding. Here, we established the role of platelet-derived protein disulfide isomerase (PDI) in reducing the allosteric disulfide bonds in GPIbalpha and enhancing the ligand-binding activity under thromboinflammatory conditions. METHODS: Bioinformatic analysis identified 2 potential allosteric disulfide bonds in GPIbalpha. Agglutination assays, flow cytometry, surface plasmon resonance analysis, a protein-protein docking model, proximity ligation assays, and mass spectrometry were used to demonstrate a direct interaction between PDI and GPIbalpha and to determine a role for PDI in regulating GPIbalpha function and platelet-neutrophil interactions. Also, real-time microscopy and animal disease models were used to study the pathophysiological role of PDI-GPIbalpha signaling under thromboinflammatory conditions. RESULTS: Deletion or inhibition of platelet PDI significantly reduced GPIbalpha-mediated platelet agglutination. Studies using PDI-null platelets and recombinant PDI or Anfibatide, a clinical-stage GPIbalpha inhibitor, revealed that the oxidoreductase activity of platelet surface-bound PDI was required for the ligand-binding function of GPIbalpha. PDI directly bound to the extracellular domain of GPIbalpha on the platelet surface and reduced the Cys4-Cys17 and Cys209-Cys248 disulfide bonds. Real-time microscopy with platelet-specific PDI conditional knockout and sickle cell disease mice demonstrated that PDI-regulated GPIbalpha function was essential for platelet-neutrophil interactions and vascular occlusion under thromboinflammatory conditions. Studies using a mouse model of ischemia/reperfusion-induced stroke indicated that PDI-GPIbalpha signaling played a crucial role in tissue damage. CONCLUSIONS: Our results demonstrate that PDI-facilitated cleavage of the allosteric disulfide bonds tightly regulates GPIbalpha function, promoting platelet-neutrophil interactions, vascular occlusion, and tissue damage under thromboinflammatory conditions. |
