scholarly journals Sphingosine kinase 1 (Sphk1) negatively regulates platelet activation and thrombus formation

2014 ◽  
Vol 307 (10) ◽  
pp. C920-C927 ◽  
Author(s):  
Patrick Münzer ◽  
Evi Schmid ◽  
Britta Walker ◽  
Anna Fotinos ◽  
Madhumita Chatterjee ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Sphingosine Kinase ◽  
Flow Chamber ◽  
Negative Regulator ◽  
Sphingosine Kinase 1 ◽  
Shear Rates ◽  
Dense Granules ◽  
Platelet Formation

Sphingosine 1-phosphate (S1P) is a powerful regulator of platelet formation. Enzymes generating S1P include sphingosine kinase 1. The present study thus explored the role of sphingosine kinase 1 in platelet formation and function. Activation-dependent platelet integrin αIIbβ3activation and secretion of platelets lacking functional sphingosine kinase 1 ( sphk1−/−) and of wild-type platelets ( sphk1+/+) were determined utilizing flow cytometry and chronolume luciferin assay. Cytosolic Ca2+activity ([Ca2+]i) and aggregation were measured using fura-2 fluorescence and aggregometry, respectively. In vitro platelet adhesion and thrombus formation were evaluated using a flow chamber with shear rates of 1,700 s−1. Activation-dependent increase of [Ca2+]i, degranulation (release of alpha and dense granules), integrin αIIbβ3activation, and aggregation were all significantly increased in sphk1−/−platelets compared with sphk1+/+platelets. Moreover, while platelet adhesion and thrombus formation under arterial shear rates were significantly augmented in Sphk1-deficient platelets, bleeding time and blood count were unaffected in sphk1−/−mice. In conclusion, sphingosine kinase 1 is a powerful negative regulator of platelet function counteracting degranulation, aggregation, and thrombus formation.

CRGT Peptide In Cytoplasm Regulates Thrombus Formation Via Dissociating c-Src-β3 Interaction

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3501-3501
Author(s):  
Jiansong Huang ◽  
Xiaofeng Shi ◽  
Wenda Xi ◽  
Ping Liu ◽  
Xiaodong Xi
Keyword(s):  
Molecular Mechanisms ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Human Platelets ◽  
Flow Conditions ◽  
Cho Cell ◽  
Integrin Αiibβ3 ◽  
Shear Rates ◽  
Platelet Adhesion And Aggregation

Abstract The RGT sequences of the integrin β3 tail directly and constitutively bind the inactive c-Src, regulating integrin αIIbβ3 signaling and platelet function. Previous work has shown that disrupting the interaction of c-Src with β3 via myristoylated RGT peptide or deletion of the RGT sequences in β3 selectively inhibits integrin αIIbβ3 outside-in signaling in platelets. However, the precise molecular mechanisms by which the Src-β3 association regulates integrin αIIbβ3 signaling need to be clarified. We found that active c-Src phosphoylated the Y747 and Y759 residues of β3 directly at the in vitro protein/protein level or in CHO cell models bearing Tac-β3 chimeras, which were devoid of the intact β3 signal transduction. Furthermore, data from mass spectrometry, [γ-32P] ATP incorporation assays and CHO cell/Tac-β3 chimeras demonstrated that the direct phosphorylation of Y747 and Y759 by active c-Src did not depend on the binding of c-Src to the RGT sequences of the β3 tail. To further investigate the biological functions of Src-β3 association in signal transduction we employed a cell-permeable and reduction-sensitive peptide (myr-AC∼CRGT), which disrupted the Src-β3 association in platelets independent of membrane-anchorage, and found that when platelets were stimulated by thrombin the c-Src activation and the phosphorylation of the tyrosine residues of the β3 tail were substantially inhibited by the presence of the peptide. These results suggest that one of the crucial biological functions of Src-β3 association is to serve as a “bridge” linking integrin signaling with the c-Src full activation and phosphorylation of the tyrosines of the β3 tail. To answer whether the RGT peptide binding to Src is able to alter the enzymatic activity of c-Src, we examined the Src-Csk association, the phosphorylation status of Y416 and Y527 of c-Src and the c-Src kinase catalytic activity. Results showed that myr-AC∼CRGT did not dissociate Csk from c-Src in resting platelets and the phosphorylation level of Y416 and Y527 of c-Src remained unaltered. Consistent data were also obtained from in vitro analysis of the c-Src kinase catalytic activity in the presence of CRGT peptide. These results suggest that myr-AC∼CRGT peptide per se does not fully activate c-Src. Myr-AC∼CRGT was also found to inhibit integrin αIIbβ3 outside-in signaling in human platelets. To examine the effect of the myr-AC∼CRGT on platelet adhesion and aggregation under flow conditions, we measured the platelet thrombus formation under different shear rates. Myr-AC∼CRGT did not affect the platelet adhesion at a wall shear rate of 125 s-1. The inability of myr-AC∼CRGT to affect platelet adhesion and aggregation remained at 500 s-1 shear rates. At 1,500 s-1, or 5,000 s-1 rates, myr-AC∼CRGT partially inhibited platelet adhesion and aggregation. These observations indicate that the Src-regulated outside-in signaling plays a pivotal role in the stable thrombus formation and the thrombus growth under flow conditions. The present study reveals novel insights into the molecular mechanisms by which c-Src regulates integrin αIIbβ3 signaling, particularly the phorsphorylation of the β3 cytoplasmic tyrosines, and provides first evidence in human platelets that the RGT peptide or derivatives regulate thrombus formation through dissociating the Src-β3 interaction. The data of this work allow us to anticipate that intracellular delivery of the RGT peptide or its analogues may have potential in the development of a new antithrombotic strategy where only the Src-β3 interaction is specifically interrupted so as to provide an effective inhibition on thrombosis together with a decent hemostasis. Disclosures: No relevant conflicts of interest to declare.

Ethanol Inhibition of Thrombus Formation on Collagen-Coated Glass

1990 ◽  
Vol 63 (03) ◽  
pp. 510-516 ◽  
Author(s):  
Charlene K Owens ◽  
Larry V Mclntire ◽  
Andrew Lasslo
Keyword(s):  
Parallel Plate ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
Mural Thrombus ◽  
Parallel Plate Flow Chamber ◽  
Shear Rates ◽  
Coated Glass ◽  
Normal Platelet ◽  
Platelet Accumulation

SummaryEpi-fluorescent video microscopy was used to evaluate the effect of ethanol on platelet mural thrombus formation. Whole blood, treated with ethanol, was perfused over collagen coated glass in a parallel-plate flow chamber at a shear rate of 1,000/s. Digital image processing and photodiode measurements were used to analyze the dynamics of thrombus growth on this surface. Ethanol concentrations as low as 0.02% v/v were found to inhibit 45 + 33% (± S.D.) of normal platelet accumulation on the slide while 0.2% v/v ethanol effected an 82 ± 15% inhibition of mural thrombus formation. While platelet adhesion to the collagen surface appeared unaffected by ethanol concentrations up to 0.1% v/v, 0.2% v/v ethanol had an effect on adhesion as well as aggregation. These results imply that low ethanol concentrations inhibit the formation of mural thrombi in a model of a damaged blood vessel at physiological shear rates. This inhibition would not be detected in systems which measure bulk aggregation, e.g. in aggregometric determinations.

Modulation of Platelet Adhesion by Antithrombin.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3954-3954
Author(s):  
Robert Loncar ◽  
Volker Stoldt ◽  
Volker Thomas ◽  
Reiner B. Zotz ◽  
Rudiger E. Scharf
Keyword(s):  
Whole Blood ◽  
Platelet Adhesion ◽  
Inverse Correlation ◽  
Flow Chamber ◽  
Low Flow ◽  
Shear Rates ◽  
Antithrombin Activity ◽  
Arterial Thrombus ◽  
Adhesion Of Platelets

Abstract In this study, we evaluated the influence of antithrombin on platelet adhesion onto immobilized fibrinogen using an in vitro system simulating venous and arterial flow. Platelets in anticoagulated whole blood (PPACK, 40μM) were labeled with mepacrine (10μM). Adhesion of platelets onto fibrinogen-coated glass cover slips was assessed in a rectangular flow chamber (shear rates of 13 s−1 to 1500 s−1). Platelets were visualized at 15 sec, 1 and 5 min following perfusion using a fluorescence laser-scan microscope. In parallel, the effects of supraphysiological supplementation of blood with antithrombin (2.8 IU/ml of blood) on platelet adhesion rates was evaluated. During perfusion, platelet adhesion onto fibrinogen linearly increased with exposure time and shear rates. Within the first min of perfusion, an inverse correlation between platelet adhesion and plasma antithrombin activity was observed at shear rates of 13 s−1 and 50 s−1 (r=−0.48 and r=−0.7, p each <0.05). Significant differences in platelet adhesion (1786±516 U vs. 823±331 U, p<0.05) related to low (92±3.3%) and high (117±4.1%) antithrombin activity was observed at a flow rate of 13s−1 within first minute. Further supplementation of anticoagulated whole blood with antithrombin (activity up to 280 %) decreased the rate of platelets adhesion (ratio of adhesion at 1 and 5 min) about 35% when compared to nonsupplemented blood (1.25 ± 0.17 vs. 1.95 ± 0.4, p=0.008). Application of heparine as anticoagulant did not enhance the antiadhesion properties of antithrombin. Our findings are in accordance with the “low shear phenomenon” of arterial thrombus progression, i.e. thrombus enlargement at distal areas with reduced flow or even stasis. Moreover, the observation that antithrombin significantly suppressed platelet adhesion onto immobilized fibrinogen under low flow conditions is of therapeutic interest and needs further evaluation.

scholarly journals Doxepin inhibits GPVI-dependent platelet Ca2+ signaling and collagen-dependent thrombus formation

2017 ◽  
Vol 312 (6) ◽  
pp. C765-C774 ◽  
Author(s):  
Sascha Geue ◽  
Britta Walker-Allgaier ◽  
Daniela Eißler ◽  
Roland Tegtmeyer ◽  
Malte Schaub ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Tricyclic Antidepressant ◽  
Thrombotic Occlusion ◽  
Shear Rates ◽  
Glycoprotein Vi ◽  
Primary Hemostasis ◽  
Intracellular Ca

Platelet adhesion, activation, and aggregation are essential for primary hemostasis, but are also critically involved in the development of acute arterial thrombotic occlusion. Stimulation of the collagen receptor glycoprotein VI (GPVI) leads to phospholipase Cγ2-dependent inositol triphosphate (IP3) production with subsequent platelet activation, due to increased intracellular Ca2+ concentration ([Ca2+]i). Although tricyclic antidepressants have been shown to potentially impair platelet activation, nothing is hitherto known about potential effects of the tricyclic antidepressant doxepin on platelet Ca2+ signaling and thrombus formation. As shown in the present study, doxepin significantly diminished the stimulatory effect of GPVI agonist collagen-related peptide (CRP) on intracellular Ca2+ release as well as subsequent extracellular Ca2+ influx. Doxepin was partially effective by impairment of CRP-dependent IP3 production. Moreover, doxepin abrogated CRP-induced platelet degranulation and integrin αIIbβ3 activation and aggregation. Finally, doxepin markedly blunted in vitro platelet adhesion to collagen and thrombus formation under high arterial shear rates (1,700−s). In conclusion, doxepin is a powerful inhibitor of GPVI-dependent platelet Ca2+ signaling, platelet activation, and thrombus formation.

scholarly journals Platelet adhesion and thrombus formation on subendothelium in platelets deficient in glycoproteins IIb-IIIa, Ib, and storage granules

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 322-330 ◽  
Author(s):  
HJ Weiss ◽  
VT Turitto ◽  
HR Baumgartner
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Dense Granule ◽  
Similar Degree ◽  
Shear Rates ◽  
Dense Granules ◽  
Absolute Requirement ◽  
Storage Granules ◽  
Platelet Thrombus ◽  
Controlled Flow

Patients whose platelets are deficient in glycoprotein (GP) Ib, IIb- IIIa (thrombasthenia), or granule substances (storage pool deficiency, SPD) were studied to define further the properties of platelets that mediate platelet adhesion and thrombus formation on subendothelium. Both nonanticoagulated and citrated blood were exposed to everted, de- endothelialized rabbit vessel segments under controlled flow conditions and shear rates varying from 650 to 3,300 sec-1. Morphometry was used to measure platelet thrombus dimensions and the percentage of the subendothelial surface covered with contact (C) or spread (S) platelets. Adhesion was defined as C + S. The results in SPD demonstrated (1) reduced thrombus dimensions in delta-SPD (pure dense granule deficiency) in proportion to the magnitude of the dense granule defect; (2) an even greater reduction in thrombus dimensions in patients with combined deficiencies of alpha and dense granules (alpha delta-SPD); and (3) impaired platelet adhesion at several conditions in alpha delta-SPD and, in delta-SPD, a hematocrit-dependent impairment of adhesion in citrated blood at 2,600 sec-1. In thrombasthenia, platelets were present as a monolayer on the subendothelial surface in both nonanticoagulated and citrated blood, indicating an absolute requirement for GPIIb-IIIa in promoting platelet-platelet interaction at all shear rates and perfusion times. Two types of abnormalities in platelet-vessel wall interactions were observed. In nonanticoagulated blood, the percentage of platelets in the C phase was consistently increased at all shear rates, but C + S values were normal. These observations indicate that platelets deficient in GPIIb-IIIa do not spread normally on the subendothelial surface exposed to nonanticoagulated blood. With citrated blood, the C + S value in thrombasthenia was reduced at both 800 and 2,600 sec-1, as in von Willebrand's disease, and a similar degree of reduction (about 50%) was observed in normal blood treated with a monoclonal antibody to GPIIb- IIIa. The findings, together with theoretical considerations, are consistent with an hypothesis that GPIIb-IIIa mediates the spreading of platelets on subendothelium following the initial attachment through GPIb and that GPIIb-IIIa may be considered an adhesion site on the platelet membrane. Abnormalities of GPIIb-IIIa may, depending on the conditions of study, result in either increased values of C platelets or decreased values of C + S. The results of the study further suggest that a complex interaction of platelet granule factors and membrane GP mediate platelet adhesion and thrombus formation.

scholarly journals Platelet adhesion and thrombus formation on subendothelium in platelets deficient in glycoproteins IIb-IIIa, Ib, and storage granules

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 322-330 ◽  
Author(s):  
HJ Weiss ◽  
VT Turitto ◽  
HR Baumgartner
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Dense Granule ◽  
Similar Degree ◽  
Shear Rates ◽  
Dense Granules ◽  
Absolute Requirement ◽  
Storage Granules ◽  
Platelet Thrombus ◽  
Controlled Flow

Abstract Patients whose platelets are deficient in glycoprotein (GP) Ib, IIb- IIIa (thrombasthenia), or granule substances (storage pool deficiency, SPD) were studied to define further the properties of platelets that mediate platelet adhesion and thrombus formation on subendothelium. Both nonanticoagulated and citrated blood were exposed to everted, de- endothelialized rabbit vessel segments under controlled flow conditions and shear rates varying from 650 to 3,300 sec-1. Morphometry was used to measure platelet thrombus dimensions and the percentage of the subendothelial surface covered with contact (C) or spread (S) platelets. Adhesion was defined as C + S. The results in SPD demonstrated (1) reduced thrombus dimensions in delta-SPD (pure dense granule deficiency) in proportion to the magnitude of the dense granule defect; (2) an even greater reduction in thrombus dimensions in patients with combined deficiencies of alpha and dense granules (alpha delta-SPD); and (3) impaired platelet adhesion at several conditions in alpha delta-SPD and, in delta-SPD, a hematocrit-dependent impairment of adhesion in citrated blood at 2,600 sec-1. In thrombasthenia, platelets were present as a monolayer on the subendothelial surface in both nonanticoagulated and citrated blood, indicating an absolute requirement for GPIIb-IIIa in promoting platelet-platelet interaction at all shear rates and perfusion times. Two types of abnormalities in platelet-vessel wall interactions were observed. In nonanticoagulated blood, the percentage of platelets in the C phase was consistently increased at all shear rates, but C + S values were normal. These observations indicate that platelets deficient in GPIIb-IIIa do not spread normally on the subendothelial surface exposed to nonanticoagulated blood. With citrated blood, the C + S value in thrombasthenia was reduced at both 800 and 2,600 sec-1, as in von Willebrand's disease, and a similar degree of reduction (about 50%) was observed in normal blood treated with a monoclonal antibody to GPIIb- IIIa. The findings, together with theoretical considerations, are consistent with an hypothesis that GPIIb-IIIa mediates the spreading of platelets on subendothelium following the initial attachment through GPIb and that GPIIb-IIIa may be considered an adhesion site on the platelet membrane. Abnormalities of GPIIb-IIIa may, depending on the conditions of study, result in either increased values of C platelets or decreased values of C + S. The results of the study further suggest that a complex interaction of platelet granule factors and membrane GP mediate platelet adhesion and thrombus formation.

scholarly journals Silencing of Sphingosine kinase 1 Affects Maturation Pathways in Mouse Neonatal Cardiomyocytes

2021 ◽  
Vol 22 (7) ◽  
pp. 3616
Author(s):  
Ewelina Jozefczuk ◽  
Piotr Szczepaniak ◽  
Tomasz Jan Guzik ◽  
Mateusz Siedlinski
Keyword(s):  
Cardiac Development ◽  
Glycogen Synthase ◽  
Sphingosine Kinase ◽  
Negative Control ◽  
Neonatal Mouse ◽  
Sphingosine Kinase 1 ◽  
Postnatal Maturation ◽  
Neonatal Cardiomyocytes ◽  
Pathological Cardiac Hypertrophy

Sphingosine kinase-1 (Sphk1) and its product, sphingosine-1-phosphate (S1P) are important regulators of cardiac growth and function. Numerous studies have reported that Sphk1/S1P signaling is essential for embryonic cardiac development and promotes pathological cardiac hypertrophy in adulthood. However, no studies have addressed the role of Sphk1 in postnatal cardiomyocyte (CM) development so far. The present study aimed to assess the molecular mechanism(s) by which Sphk1 silencing might influence CMs development and hypertrophy in vitro. Neonatal mouse CMs were transfected with siRNA against Sphk1 or negative control, and subsequently treated with 1 µM angiotensin II (AngII) or a control buffer for 24 h. The results of RNASeq analysis revealed that diminished expression of Sphk1 significantly accelerated neonatal CM maturation by inhibiting cell proliferation and inducing developmental pathways in the stress (AngII-induced) conditions. Importantly, similar effects were observed in the control conditions. Enhanced maturation of Sphk1-lacking CMs was further confirmed by the upregulation of the physiological hypertrophy-related signaling pathway involving Akt and downstream glycogen synthase kinase 3 beta (Gsk3β) downregulation. In summary, we demonstrated that the Sphk1 silencing in neonatal mouse CMs facilitated their postnatal maturation in both physiological and stress conditions.

scholarly journals Sphingosine Kinase 1 Is a Negative Regulator of CD4+ Th1 Cells

2005 ◽  
Vol 175 (10) ◽  
pp. 6580-6588 ◽  
Author(s):  
Jianfei Yang ◽  
Brian E. Castle ◽  
Adedayo Hanidu ◽  
Lisa Stevens ◽  
Yang Yu ◽  
...  
Keyword(s):  
Sphingosine Kinase ◽  
Negative Regulator ◽  
Th1 Cells ◽  
Sphingosine Kinase 1

Sphingosine kinase 1 regulates lysyl oxidase through STAT3 in hyperoxia-mediated neonatal lung injury

Thorax ◽  
2021 ◽  
pp. thoraxjnl-2020-216469
Author(s):  
Alison W Ha ◽  
Tao Bai ◽  
David L Ebenezer ◽  
Tanvi Sethi ◽  
Tara Sudhadevi ◽  
...  
Keyword(s):  
Lung Injury ◽  
Lysyl Oxidase ◽  
Critical Role ◽  
Sphingosine Kinase ◽  
In Vivo Studies ◽  
Sphingosine Kinase 1 ◽  
Neonatal Lung ◽  
Neonatal Lung Injury

IntroductionNeonatal lung injury as a consequence of hyperoxia (HO) therapy and ventilator care contribute to the development of bronchopulmonary dysplasia (BPD). Increased expression and activity of lysyl oxidase (LOX), a key enzyme that cross-links collagen, was associated with increased sphingosine kinase 1 (SPHK1) in human BPD. We, therefore, examined closely the link between LOX and SPHK1 in BPD.MethodThe enzyme expression of SPHK1 and LOX were assessed in lung tissues of human BPD using immunohistochemistry and quantified (Halo). In vivo studies were based on Sphk1−/− and matched wild type (WT) neonatal mice exposed to HO while treated with PF543, an inhibitor of SPHK1. In vitro mechanistic studies used human lung microvascular endothelial cells (HLMVECs).ResultsBoth SPHK1 and LOX expressions were increased in lungs of patients with BPD. Tracheal aspirates from patients with BPD had increased LOX, correlating with sphingosine-1-phosphate (S1P) levels. HO-induced increase of LOX in lungs were attenuated in both Sphk1−/− and PF543-treated WT mice, accompanied by reduced collagen staining (sirius red). PF543 reduced LOX activity in both bronchoalveolar lavage fluid and supernatant of HLMVECs following HO. In silico analysis revealed STAT3 as a potential transcriptional regulator of LOX. In HLMVECs, following HO, ChIP assay confirmed increased STAT3 binding to LOX promoter. SPHK1 inhibition reduced phosphorylation of STAT3. Antibody to S1P and siRNA against SPNS2, S1P receptor 1 (S1P1) and STAT3 reduced LOX expression.ConclusionHO-induced SPHK1/S1P signalling axis plays a critical role in transcriptional regulation of LOX expression via SPNS2, S1P1 and STAT3 in lung endothelium.

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