Genetic and Pharmacological Analyses of Syk Function in IIbβ3 Signaling in Platelets

Blood ◽  
1999 ◽  
Vol 93 (8) ◽  
pp. 2645-2652 ◽  
Author(s):  
Debbie A. Law ◽  
Lisa Nannizzi-Alaimo ◽  
Kathleen Ministri ◽  
Paul E. Hughes ◽  
Jane Forsyth ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Platelet Adhesion ◽  
Kinase Inhibitor ◽  
Human Platelet ◽  
Human Platelets ◽  
Protein Tyrosine Kinases ◽  
Fibrinogen Binding ◽  
Multiple Protein ◽  
Inside Out

Agonists induce inside-out IIbβ3signaling resulting in fibrinogen binding and platelet aggregation. These in turn trigger outside-in signaling resulting in further platelet stimulation. Because the Syk tyrosine kinase is activated during both phases of integrin signaling, we evaluated its role in IIbβ3 function in murine platelets rendered null for Syk by gene targeting and in human platelets incubated with piceatannol, a tyrosine kinase inhibitor reportedly selective for Syk. Both Syk null murine platelets and piceatannol-treated human platelets exhibited a partial, but statistically significant defect in activation of IIbβ3 by adenine diphosphate (ADP) ± epinephrine as assessed by fibrinogen binding. Syk null platelets adhered normally to immobilized fibrinogen, and mice with these platelets exhibited normal tail bleeding times. In contrast, piceatannol treatment of human platelets completely inhibited platelet adhesion to immobilized fibrinogen. The discrepancy in extent of integrin dysfunction between murine and human platelet models may be due to lack of specificity of piceatannol, because this compound inhibited the activity of Src and FAK as well as Syk and also reduced tyrosine phosphorylation of multiple platelet proteins. These results provide genetic evidence that Syk plays a role in IIbβ3 signaling in platelets and pharmacological evidence that, although piceatannol also inhibits IIbβ3 signaling, it does so by inhibtion of multiple protein tyrosine kinases.

Genetic and Pharmacological Analyses of Syk Function in IIbβ3 Signaling in Platelets

Blood ◽  
1999 ◽  
Vol 93 (8) ◽  
pp. 2645-2652 ◽  
Author(s):  
Debbie A. Law ◽  
Lisa Nannizzi-Alaimo ◽  
Kathleen Ministri ◽  
Paul E. Hughes ◽  
Jane Forsyth ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Platelet Adhesion ◽  
Kinase Inhibitor ◽  
Human Platelet ◽  
Human Platelets ◽  
Protein Tyrosine Kinases ◽  
Fibrinogen Binding ◽  
Multiple Protein ◽  
Inside Out

Abstract Agonists induce inside-out IIbβ3signaling resulting in fibrinogen binding and platelet aggregation. These in turn trigger outside-in signaling resulting in further platelet stimulation. Because the Syk tyrosine kinase is activated during both phases of integrin signaling, we evaluated its role in IIbβ3 function in murine platelets rendered null for Syk by gene targeting and in human platelets incubated with piceatannol, a tyrosine kinase inhibitor reportedly selective for Syk. Both Syk null murine platelets and piceatannol-treated human platelets exhibited a partial, but statistically significant defect in activation of IIbβ3 by adenine diphosphate (ADP) ± epinephrine as assessed by fibrinogen binding. Syk null platelets adhered normally to immobilized fibrinogen, and mice with these platelets exhibited normal tail bleeding times. In contrast, piceatannol treatment of human platelets completely inhibited platelet adhesion to immobilized fibrinogen. The discrepancy in extent of integrin dysfunction between murine and human platelet models may be due to lack of specificity of piceatannol, because this compound inhibited the activity of Src and FAK as well as Syk and also reduced tyrosine phosphorylation of multiple platelet proteins. These results provide genetic evidence that Syk plays a role in IIbβ3 signaling in platelets and pharmacological evidence that, although piceatannol also inhibits IIbβ3 signaling, it does so by inhibtion of multiple protein tyrosine kinases.

scholarly journals Tyrosine kinases and phosphoinositide metabolism in thrombin-stimulated human platelets

1993 ◽  
Vol 292 (3) ◽  
pp. 851-856 ◽  
Author(s):  
C Guinebault ◽  
B Payrastre ◽  
C Sultan ◽  
G Mauco ◽  
M Breton ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Inhibitor ◽  
Human Platelet ◽  
Inositol Phosphate ◽  
Human Platelets ◽  
Significant Inhibition ◽  
Regulatory Subunit ◽  
Phosphoinositide Metabolism ◽  
Inositol Phosphate Production

In this study we have examined the implication of tyrosine kinase activities in aggregation, 5-hydroxytryptamine secretion and mainly phosphoinositide metabolism in response to human platelet stimulation by thrombin. Using the potent tyrosine kinase inhibitor tyrphostin AG-213, we have observed a significant inhibition of aggregation and 5-hydroxytryptamine release; however, this percentage inhibition was lower at high thrombin concentrations. On the other hand, tyrphostin treatment of metabolically 32P-labelled platelets significantly inhibited the thrombin-dependent accumulation of PtdIns(3,4)P2, which involves at least a PtdIns 3-kinase and/or a PtdIns3P 4-kinase, whereas the synthesis of phosphatidic acid (PtdOH), a good reflection of the phospholipase C (PLC) activation in platelets, was partially blocked. Inositol phosphate production was also inhibited by about 40% when tyrphostin-treated platelets were stimulated with thrombin. In addition, we show by Western-blot analysis that PLC gamma 1, as well as the regulatory subunit (p85) of the PtdIns 3-kinase, were present in the anti-phosphotyrosine immunoprecipitate isolated from thrombin-stimulated platelets. Furthermore, tyrphostin treatment clearly decreased the PLC gamma 1 and p85 contents in such an anti-phosphotyrosine immunoprecipitate. Our results provide the first evidence for a direct or indirect regulation of PtdIns(3,4)P2 accumulation and PLC gamma 1 activity by tyrosine phosphorylation during thrombin stimulation of human platelets.

scholarly journals CGP 57148, a Tyrosine Kinase Inhibitor, Inhibits the Growth of Cells Expressing BCR-ABL, TEL-ABL, and TEL-PDGFR Fusion Proteins

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4947-4952 ◽  
Author(s):  
Martin Carroll ◽  
Sayuri Ohno-Jones ◽  
Shu Tamura ◽  
Elisabeth Buchdunger ◽  
Jürg Zimmermann ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Philadelphia Chromosome ◽  
Lymphocytic Leukemia ◽  
Protein Tyrosine Kinases ◽  
Protein Tyrosine

Abstract CGP 57148 is a compound of the 2-phenylaminopyrimidine class that selectively inhibits the tyrosine kinase activity of the ABL and the platelet-derived growth factor receptor (PDGFR) protein tyrosine kinases. We previously showed that CGP 57148 selectively kills p210BCR-ABL–expressing cells. To extend these observations, we evaluated the ability of CGP 57148 to inhibit other activated ABL tyrosine kinases, including p185BCR-ABL and TEL-ABL. In cell-based assays of ABL tyrosine phosphorylation, inhibition of ABL kinase activity was observed at concentrations similar to that reported for p210BCR-ABL. Consistent with the in vitro profile of this compound, the growth of cells expressing activated ABL protein tyrosine kinases was inhibited in the absence of exogenous growth factor. Growth inhibition was also observed with a p185BCR-ABL–positive acute lymphocytic leukemia (ALL) cell line generated from a Philadelphia chromosome–positive ALL patient. As CGP 57148 inhibits the PDGFR kinase, we also showed that cells expressing an activated PDGFR tyrosine kinase, TEL-PDGFR, are sensitive to this compound. Thus, this compound may be useful for the treatment of a variety of BCR-ABL–positive leukemias and for treatment of the subset of chronic myelomonocytic leukemia patients with a TEL-PDGFR fusion protein.

scholarly journals Tyrosine kinases activate store-mediated Ca2+ entry in human platelets through the reorganization of the actin cytoskeleton

2000 ◽  
Vol 351 (2) ◽  
pp. 429-437 ◽  
Author(s):  
Juan A. ROSADO ◽  
Darren GRAVES ◽  
Stewart O. SAGE
Keyword(s):  
Tyrosine Kinase ◽  
Actin Cytoskeleton ◽  
Tyrosine Kinases ◽  
Actin Polymerization ◽  
Kinase Inhibitor ◽  
Coupling Model ◽  
Human Platelets ◽  
Ras Proteins ◽  
Model Treatment ◽  
Independent Effects

We have recently reported that store-mediated Ca2+ entry in platelets is likely to be mediated by a reversible trafficking and coupling of the endoplasmic reticulum with the plasma membrane, a model termed ‘secretion-like coupling’. In this model the actin cytoskeleton plays a key regulatory role. Since tyrosine kinases have been shown to be important for Ca2+ entry in platelets and other cells, we have now investigated the possible involvement of tyrosine kinases in the secretion-like-coupling model. Treatment of platelets with thrombin or thapsigargin induced actin polymerization by a calcium-independent pathway. Methyl 2,5-dihydroxycinnamate, a tyrosine kinase inhibitor, prevented thrombin- or thapsigargin-induced actin polymerization. The effects of tyrosine kinases in store-mediated Ca2+ entry were found to be entirely dependent on the actin cytoskeleton. PP1, an inhibitor of the Src family of proteins, partially inhibited store-mediated Ca2+ entry. In addition, depletion of intracellular Ca2+ stores stimulated cytoskeletal association of the cytoplasmic tyrosine kinase pp60src, a process that was sensitive to treatment with cytochalasin D and PP1, but not to inhibition of Ras proteins using prenylcysteine analogues. Finally, combined inhibition of both Ras proteins and tyrosine kinases resulted in complete inhibition of Ca2+ entry, suggesting that these two families of proteins have independent effects in the activation of store-mediated Ca2+ entry in human platelets.

scholarly journals Platelet adhesion to collagen via the α2β1 integrin under arterial flow conditions causes rapid tyrosine phosphorylation of pp125FAK

1993 ◽  
Vol 296 (3) ◽  
pp. 543-547 ◽  
Author(s):  
R Polanowska-Grabowska ◽  
M Geanacopoulos ◽  
A R L Gear
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Platelet Adhesion ◽  
Kinase Inhibitor ◽  
Human Platelets ◽  
Arterial Flow ◽  
Flow Conditions ◽  
Beta 1 Integrin ◽  
Platelet Spreading ◽  
Α2β1 Integrin

Adhesion of human platelets to collagen under arterial flow conditions mediated by the alpha 2 beta 1 integrin increased tyrosine phosphorylation of several proteins, one of which was the focal adhesion tyrosine kinase, pp125FAK. Tyrosine phosphorylation of pp125FAK did not occur in non-adherent flowing platelets or in platelets attached to poly(L-lysine). Neither adhesion nor tyrosine phosphorylation was affected by pretreatment of platelets with GRGDSP peptide or by anti-alpha IIb beta 3 monoclonal antibody P2. Adherent platelets retained their discoid shape, suggesting that induction of pp125FAK precedes platelet spreading. The tyrosine kinase inhibitor erbstatin decreased tyrosine phosphorylation in non-stimulated platelets and blocked platelet adhesion. These results suggest that pp125FAK plays an important role in platelet adhesion to collagen via the alpha 2 beta 1 integrin.

scholarly journals CGP 57148, a Tyrosine Kinase Inhibitor, Inhibits the Growth of Cells Expressing BCR-ABL, TEL-ABL, and TEL-PDGFR Fusion Proteins

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4947-4952 ◽  
Author(s):  
Martin Carroll ◽  
Sayuri Ohno-Jones ◽  
Shu Tamura ◽  
Elisabeth Buchdunger ◽  
Jürg Zimmermann ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Philadelphia Chromosome ◽  
Lymphocytic Leukemia ◽  
Protein Tyrosine Kinases ◽  
Protein Tyrosine

CGP 57148 is a compound of the 2-phenylaminopyrimidine class that selectively inhibits the tyrosine kinase activity of the ABL and the platelet-derived growth factor receptor (PDGFR) protein tyrosine kinases. We previously showed that CGP 57148 selectively kills p210BCR-ABL–expressing cells. To extend these observations, we evaluated the ability of CGP 57148 to inhibit other activated ABL tyrosine kinases, including p185BCR-ABL and TEL-ABL. In cell-based assays of ABL tyrosine phosphorylation, inhibition of ABL kinase activity was observed at concentrations similar to that reported for p210BCR-ABL. Consistent with the in vitro profile of this compound, the growth of cells expressing activated ABL protein tyrosine kinases was inhibited in the absence of exogenous growth factor. Growth inhibition was also observed with a p185BCR-ABL–positive acute lymphocytic leukemia (ALL) cell line generated from a Philadelphia chromosome–positive ALL patient. As CGP 57148 inhibits the PDGFR kinase, we also showed that cells expressing an activated PDGFR tyrosine kinase, TEL-PDGFR, are sensitive to this compound. Thus, this compound may be useful for the treatment of a variety of BCR-ABL–positive leukemias and for treatment of the subset of chronic myelomonocytic leukemia patients with a TEL-PDGFR fusion protein.

scholarly journals Role of Protein Tyrosine Kinase p53/56lyn in Diminished Lipopolysaccharide Priming of Formylmethionylleucyl- phenylalanine-Induced Superoxide Production in Human Newborn Neutrophils

2004 ◽  
Vol 72 (11) ◽  
pp. 6455-6462 ◽  
Author(s):  
Sen Rong Yan ◽  
David M. Byers ◽  
Robert Bortolussi
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Critical Role ◽  
Polymorphonuclear Neutrophils ◽  
Protein Tyrosine Kinases ◽  
Protein Tyrosine ◽  
Adult Cells

ABSTRACT Human newborns are more susceptible than adults to bacterial infection. With gram-negative bacteria, this may be due to a diminished response of newborn leukocytes to lipopolysaccharide (LPS). Since protein tyrosine kinase inhibition abolishes LPS priming in adult cells, we hypothesized that protein tyrosine kinases may have a critical role in LPS priming of polymorphonuclear neutrophils (PMNs) and that newborn PMNs may have altered protein tyrosine kinase activities. In the present study, we investigated the role of src family protein tyrosine kinases in the LPS response of newborn PMNs compared to adult cells. In a respiratory assay, the LPS-primed increase in formylmethionylleucylphenylalanine (fMLP)-triggered O2 − release by adult PMNs was greatly decreased by PP1 [4-amino-5-(4-methyphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine], a src kinase inhibitor, to the level of untreated newborn PMNs, in which LPS failed to prime. LPS activated the src-like kinases p59hck (HCK) and p58fgr (FGR) in both adult and newborn PMNs but increased the activation of p53/56 lyn (LYN) only in adult cells. In newborn PMNs, LYN was highly phosphorylated independent of LPS. We evaluated subcellular fractions of PMNs and found that the phosphorylated form of LYN was mainly in the Triton-extractable, cytosolic fraction in adult PMNs, while in newborn cells it was located mainly in Triton-insoluble, granule- and membrane-associated fractions. In contrast, the phosphorylated mitogen-activated protein kinases ERK1/2 and p38 were mainly detected in the cytosol in both adult and newborn PMNs. These data indicate a role for LYN in the regulation of LPS priming. The trapping of phosphorylated LYN in the membrane-granule fraction in newborn PMNs may contribute to the deficiency of newborn cells in responding to LPS stimulation.

Effects of a Monoclonal Antibody to Glycoprotein IIb/IIIa (P256) and of Enzymically Derived Fragments of P256 on Human Platelets

1991 ◽  
Vol 65 (04) ◽  
pp. 432-437 ◽  
Author(s):  
A W J Stuttle ◽  
M J Powling ◽  
J M Ritter ◽  
R M Hardisty
Keyword(s):  
Monoclonal Antibody ◽  
Flow Cytometry ◽  
Platelet Aggregation ◽  
Calcium Ions ◽  
Human Platelet ◽  
Human Platelets ◽  
In Vivo Detection ◽  
Fibrinogen Binding ◽  
Specific Antagonist

SummaryThe anti-platelet monoclonal antibody P256 is currently undergoing development for in vivo detection of thrombus. We have examined the actions of P256 and two fragments on human platelet function. P256, and its divalent fragment, caused aggregation at concentrations of 10−9−3 × 10−8 M. A monovalent fragment of P256 did not cause aggregation at concentrations up to 10−7 M. P256–induced platelet aggregation was dependent upon extracellular calcium ions as assessed by quin2 fluorescence. Indomethacin partially inhibited platelet aggregation and completely inhibited intracellular calcium mobilisation. Apyrase caused partial inhibition of aggregation. Aggregation induced by the divalent fragment was dependent upon fibrinogen and was inhibited by prostacyclin. Aggregation induced by the whole antibody was only partially dependent upon fibrinogen, but was also inhibited by prostacyclin. P256 whole antibody was shown, by flow cytometry, to induce fibrinogen binding to indomethacin treated platelets. Monovalent P256 was shown to be a specific antagonist for aggregation induced by the divalent forms. In–111–labelled monovalent fragment bound to gel-filtered platelets in a saturable and displaceable manner. Monovalent P256 represents a safer form for in vivo applications

scholarly journals The role of Akt in the signaling pathway of the glycoprotein Ib-IX–induced platelet activation

Blood ◽  
2008 ◽  
Vol 111 (2) ◽  
pp. 658-665 ◽  
Author(s):  
Hong Yin ◽  
Aleksandra Stojanovic ◽  
Nissim Hay ◽  
Xiaoping Du
Keyword(s):  
Signaling Pathway ◽  
Platelet Adhesion ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Integrin Activation ◽  
Akt Inhibitor ◽  
Glycoprotein Ib ◽  
Platelet Spreading ◽  
Von Willebrand ◽  
Inside Out

The platelet von Willebrand factor (vWF) receptor, glycoprotein Ib-IX (GPIb-IX), mediates platelet adhesion and induces signaling leading to integrin activation. Phosphoinositol 3-kinase (PI3K) is important in GPIb-IX–mediated signaling. PI3K–dependent signaling mechanisms, however, are unclear. We show that GPIb-IX–induced platelet aggregation and stable adhesion under flow were impaired in mouse platelets deficient in PI3K effectors, Akt1 and Akt2, and in human platelets treated with an Akt inhibitor, SH-6. Akt1 and Akt2 play important roles in early GPIb-IX signaling independent of Syk, adenosine diphosphate (ADP), or thromboxane A2 (TXA2), in addition to their recognized roles in ADP- and TXA2–dependent secondary amplification pathways. Knockout of Akt1 or Akt2 diminished platelet spreading on vWF but not on immobilized fibrinogen. Thus, Akt1 and Akt2 are both required only in the GPIb-IX–mediated integrin activation (inside-out signaling). In contrast, PI3K inhibitors abolished platelet spreading on both vWF and fibrinogen, indicating a role for PI3K in integrin outside-in signaling distinct from that in GPIb-IX–mediated inside-out signaling. Furthermore, Akt1- or Akt2-deficiency diminished vWF–induced cGMP elevation, and their inhibitory effects on GPIb-IX–dependent platelet adhesion were reversed by exogenous cGMP. Thus, Akt1 and Akt2 mediate GPIb-IX signaling via the cGMP–dependent signaling pathway.

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