Abstract
Binding of von Willebrand factor (VWF) to the platelet membrane glycoprotein (GP) Ib-IX-V complex initiates a signaling cascade that causes alphaIIbbeta3 activation and platelet aggregation. Previous work demonstrated that botrocetin (bt)/VWF-mediated agglutination activates alphaIIbbeta3 and elicits adenosine triphosphate (ATP) secretion in a thromboxane A2 (TxA2)- and Ca2+-dependent manner. This agglutination-elicited TxA2 production occurs in the absence of ATP secretion. However, the signaling components and signaling network or pathway activated by GPIb-mediated agglutination to cause TxA2 production have not been identified. Therefore, the focus of this study was to elucidate at least part of the signal transduction network or pathway activated by GPIb-mediated agglutination to cause TxA2 production. The phosphatidylinositol 3-kinase (PI3K) selective inhibitor wortmannin, and mouse platelets deficient in Lyn, Src, Syk, Src homology 2 (SH2) domain-containing leukocyte protein 76 (SLP-76), phospholipase Cgamma2 (PLCgamma2), linker for activation of T cells (LAT), or Fc receptor gamma-chain (FcRgamma-chain) were used for these studies. LAT and FcRgamma-chain were found not to be required for agglutination-driven TxA2 production or activation of alphaIIbbeta3, but were required for granule secretion and aggregation. The results also clearly demonstrate that bt/VWF-mediated agglutination-induced TxA2 production is dependent on signaling apparently initiated by Lyn, enhanced by Src, and propagated through Syk, SLP-76, PI3K, PLCgamma2, and protein kinase C (PKC).
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenosine Triphosphate / metabolism
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Animals
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Blood Platelets / drug effects
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Blood Platelets / metabolism
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CD36 Antigens / metabolism*
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Crotalid Venoms / pharmacology*
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Enzyme Precursors / deficiency
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Enzyme Precursors / genetics
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Enzyme Precursors / metabolism
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Intracellular Signaling Peptides and Proteins
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Mice
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Mice, Knockout
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Phosphatidylinositol 3-Kinases / metabolism
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Phospholipase C gamma
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Platelet Aggregation / drug effects
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Platelet Aggregation / physiology
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Platelet Glycoprotein GPIIb-IIIa Complex / metabolism*
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Platelet Glycoprotein GPIb-IX Complex / metabolism*
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Protein Kinase C / metabolism
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Protein Kinase Inhibitors / pharmacology
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Protein-Tyrosine Kinases / deficiency
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Protein-Tyrosine Kinases / genetics
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Protein-Tyrosine Kinases / metabolism
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Proto-Oncogene Proteins pp60(c-src) / antagonists & inhibitors
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Proto-Oncogene Proteins pp60(c-src) / deficiency
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Proto-Oncogene Proteins pp60(c-src) / genetics
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Proto-Oncogene Proteins pp60(c-src) / metabolism
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Receptors, Fc / metabolism
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Signal Transduction* / drug effects
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Syk Kinase
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Thromboxane A2 / metabolism*
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Type C Phospholipases / deficiency
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Type C Phospholipases / genetics
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Type C Phospholipases / metabolism
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src-Family Kinases / metabolism
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von Willebrand Factor / pharmacology*
Substances
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CD36 Antigens
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Crotalid Venoms
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Enzyme Precursors
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Intracellular Signaling Peptides and Proteins
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Platelet Glycoprotein GPIIb-IIIa Complex
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Platelet Glycoprotein GPIb-IX Complex
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Protein Kinase Inhibitors
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Receptors, Fc
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von Willebrand Factor
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Thromboxane A2
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botrocetin
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Adenosine Triphosphate
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Phosphatidylinositol 3-Kinases
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Protein-Tyrosine Kinases
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Proto-Oncogene Proteins pp60(c-src)
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Syk Kinase
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Syk protein, mouse
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lyn protein-tyrosine kinase
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src-Family Kinases
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Protein Kinase C
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Type C Phospholipases
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Phospholipase C gamma