title: Platelet protein disulfide isomerase is required for thrombus formation but not for hemostasis in mice.
abstract: Protein disulfide isomerase (PDI) derived from intravascular cells is required for thrombus formation. However, it remains unclear whether platelet PDI contributes to the process. Using platelet-specific PDI-deficient mice, we demonstrate that PDI-null platelets have defects in aggregation and adenosine triphosphate secretion induced by thrombin, collagen, and adenosine diphosphate. Such defects were rescued by wild-type but not mutant PDI, indicating that the isomerase activity of platelet surface PDI is critical for the regulatory effect. PDI-deficient platelets expressed increased levels of intracellular ER protein 57 (ERp57) and ERp72. Platelet PDI regulated αIIbβ3 integrin activation but not P-selectin exposure, Ca(2+) mobilization, β3-talin1 interaction, or platelet spreading on immobilized fibrinogen. Inhibition of ERp57 further diminished αIIbβ3 integrin activation and aggregation of activated PDI-deficient platelets, suggesting distinct roles of PDI and ERp57 in platelet functions. We found that platelet PDI is important for thrombus formation on collagen-coated surfaces under shear. Intravital microscopy demonstrates that platelet PDI is important for platelet accumulation but not initial adhesion and fibrin generation following laser-induced arteriolar injury. Tail bleeding time in platelet-specific PDI-deficient mice were not significantly increased. Our results provide important evidence that platelet PDI is essential for thrombus formation but not for hemostasis in mice.
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612, USA.
authors.forename: Kyungho
authors.initials: K
authors.lastname: Kim
authors.forename: Eunsil
authors.initials: E
authors.lastname: Hahm
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Lisa-Marie
authors.initials: LM
authors.lastname: Holbrook
authors.forename: Parvathy
authors.initials: P
authors.lastname: Sasikumar
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Stanley
authors.forename: Masuko
authors.initials: M
authors.lastname: Ushio-Fukai
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Gibbins
authors.forename: Jaehyung
authors.initials: J
authors.lastname: Cho
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D005337:Fibrin / Q000378:metabolism; D006487:Hemostasis; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009504:Neutrophils / Q000378:metabolism; D010766:Phosphorylation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000097:blood* / Q000378:metabolism / Q000502:physiology*; D033081:Shear Strength; D013314:Stress, Mechanical; D013927:Thrombosis / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C062477:endoplasmic reticulum glycoprotein p72; D000255:Adenosine Triphosphate; D005337:Fibrin; C513195:Pdia3 protein, mouse; D019704:Protein Disulfide-Isomerases; D002118:Calcium