Inhibition of platelet function by an aspirin-insensitive endothelial cell ADPase. Thromboregulation by endothelial cells.

Marcus, Aaron J.; Safier, Lenore B.; Hajjar, Katherine A.; Ullman, H L; Islam, Naziba; Broekman, M. Johan; Eiroa, A M

doi:10.1172/jci115485

Cited by 167 publications

(105 citation statements)

References 21 publications

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“…Accordingly, RPAI-1 inhibits platelet aggregation induced by low doses of ADP; it also attenuates platelet aggregation triggered by low concentrations of collagen, arachidonic acid, and thromboxane mimetic U46619. It is well known that platelet aggregation by low concentrations of these three agonists is highly dependent on ADP released from platelets; in fact, platelets treated with apyrase (64,65), ADP receptor antagonists (20,66,67), indomethacin (that attenuates platelet secretion) (68 -70), respond poorly to low concentrations of collagen, U46619, and arachidonic acid. In these cases, as described here for RPAI-1, platelet aggregation is characterized by a slow aggregation rate (slope) and a right-shifted dose-response curve.…”

Section: Discussionmentioning

confidence: 99%

Purification, Cloning, Expression, and Mechanism of Action of a Novel Platelet Aggregation Inhibitor from the Salivary Gland of the Blood-sucking Bug, Rhodnius prolixus

Francischetti

Ribeiro

Champagne

et al. 2000

Journal of Biological Chemistry

109

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Rhodnius prolixus aggregation inhibitor 1 (RPAI-1), a 19-kDa protein isolated from the salivary gland of R. prolixus, was purified by strong cation exchange and reverse-phase high performance liquid chromatographies. Based on 49 amino-terminal amino acid sequences of RPAI-1, primers were produced to generate probes to screen an R. prolixus salivary gland cDNA library. A phage containing the full-length clone of RPAI-1 codes for a mature protein of 155 amino acids. RPAI-1 shows sequence homology to triabin and pallidipin, lipocalins from Triatoma pallidipennis. The cDNA sequence was cloned in Pet17B Escherichia coli expression vector, producing an active peptide. RPAI-1 inhibits human platelet-rich plasma aggregation triggered by low concentrations of ADP, collagen, arachidonic acid, thromboxane A 2 mimetics (U46619), and very low doses of thrombin and convulxin. Here we show that ADP is the target of RPAI-1 since (i) RPAI-1 inhibits ADP-dependent large aggregation formation and secretion triggered by U46619, without affecting Ca 2؉ increase and shape change; (ii) ADP restored the inhibition of U46619-induced platelet aggregation by RPAI-1, (iii) PGE 1 -induced increase of cAMP (which is antagonized by U46619 in an ADP-dependent manner) was restored by RPAI-1, (iv) RPAI-1 inhibits low concentrations of ADP-mediated responses of indomethacintreated platelets, and (v) RPAI-1 binds to ADP, as assessed by large zone chromatography. RPAI-1 affects neither integrin ␣ 2 ␤ 1 -nor glycoprotein VI-mediated platelet responses. We conclude that RPAI-1 is the first lipocalin described that inhibits platelet aggregation by a novel mechanism, binding to ADP.Normal hemostasis is initiated when platelets are exposed to subendothelial matrix, where they adhere to collagen via specific cell-surface receptors. This adhesion step is followed by platelet activation that is accompanied by synthesis and release of pro-aggregatory molecules such as TXA 2 1 and ADP, which amplify platelet responses to collagen and recruit additional platelets to the site of injury, respectively (1). The concerted action of collagen, ADP, and TXA 2 activates specific signaling pathways, generating a number of second messengers and leading to the functional expression of integrin ␣ IIb ␤ 3 , the fibrinogen receptor on platelets (1). Binding of fibrinogen to platelets mediates platelet aggregation, the final common response of activated platelets to most agonists. In addition to platelet aggregation, normal hemostasis involves activation of the blood coagulation cascade and vasoconstriction, making it a very redundant system (2). Redundancy is also observed in terms of the receptors involved in platelet responses for each specific agonist. It has now become clear that physiologic platelet agonists stimulate platelets by more than one receptor, and specific platelet responses involve distinct receptors. Accordingly, it has been shown that integrin ␣ 2 ␤ 1 receptor mediates platelet adhesion to collagen, whereas GPVI induces most of the signal involved in plat...

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Section: Discussionmentioning

confidence: 99%

Purification, Cloning, Expression, and Mechanism of Action of a Novel Platelet Aggregation Inhibitor from the Salivary Gland of the Blood-sucking Bug, Rhodnius prolixus

Francischetti

Ribeiro

Champagne

et al. 2000

Journal of Biological Chemistry

109

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“…Endothelial cells also synthesise tissue factor pathway inhibitor, which plays an important role in the down-regulation of the initial phase of coagulation [61], and protein S, which is a co-factor to APC and thereby promotes the anticoagulant activity of APC [62]. In addition to these anticoagulant and profibrinolytic effects, EC can also control the reactivity of platelets via synthesis of ecto-adenosine diphosphatase [63], prostaglandin I 2 [64] and nitric oxide (NO), also known as endothelium-derived relaxing factor [65].…”

Section: Endothelial Cellsmentioning

confidence: 99%

Inhibition of carboxypeptidase U (TAFIa) activity improves rt-PA induced thrombolysis in a dog model of coronary artery thrombosis

Björkman

Abrahamsson

Nerme

et al. 2005

Thrombosis Research

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The physiologically most important activator of intravascular fibrinolysis is tissue-type plasminogen activator (t-PA) released from endothelial cells. In man, sympathomimetic drugs increase the systemic concentration of t-PA. It is therefore of interest to investigate whether cardiac sympathetic activation can induce a local t-PA release, which could counteract intra-coronary clot formation.Thrombolytic therapy with recombinant t-PA (rt-PA) is effective in acute myocardial infarction, but the treatment is limited by a fairly slow reperfusion rate and frequent early reocclusions. A potential mechanism behind early reocclusions might be that active thrombin is released from the thrombus during thrombolytic therapy. Thrombin has recently been shown to activate procarboxypeptidase U, which in its active form (CPU) down-regulates endogenous fibrinolysis. Therefore, one way of improving thrombolytic efficacy may be to combine rt-PA with a lowmolecular weight direct thrombin inhibitor, which theoretically could have a pro-fibrinolytic effect, either by inhibition of fibrin-bound thrombin and/or by inhibition of CPU activation. An alternative way may be direct inhibition of CPU.In a porcine model, experimental activation of cardiac sympathetic nerves by electrical stimulation at 1 and 8 Hz induced 5-and 20-fold increase in the release of both total and active t-PA together with frequency-dependent increases in heart rate, blood pressure, and coronary blood flow. The t-PA release was independent of the heart rate and coronary flow response, but local infusion of isoprenaline suggested that part of the t-PA response was mediated by stimulation of β-adrenergic receptors. Next, we studied the combined effect of rt-PA and thrombin inhibitors (melagatran, hirudin and heparin) in a canine model of copper coil-induced coronary thrombosis. The profibrinolytic effect of rt-PA, either measured as patency rate or time-to-patency, was significantly enhanced with the low-molecular weight direct thrombin inhibitor melagatran, but to a lesser degree by hirudin and heparin. In the same model it was shown that active CPU is produced locally in the coronary vascular bed during both thrombus formation and clot lysis. Inhibition of thrombin attenuated CPU formation and improved patency. A similar effect was obtained with a direct inhibitor of CPU.In conclusion, the coronary t-PA response to sympathetic stimulation may constitute a thromboprotective defence mechanism to counteract its prothrombotic effects on the systemic level. Furthermore, direct thrombin and/or CPU inhibition may be potential targets for prevention of thrombus formation via facilitation of the endogenous fibrinolytic system.

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“…Two of these produce the autacoids nitric oxide (NO) and prostacyclin upon interaction with agonists, while the third is based on CD39, an integral component of the endothelial cell surface. CD39 exerts Ca 2+ /Mg 2+ -dependent diphosphohydrolase (ATPDase, apyrase) activity [2,3]. ATPDase regulates the concentrations of extracellular tri-and diphosphate nucleosides, which appear in the blood as a consequence of blood cell lysis, tissue damage, and the secretory response of blood platelets.…”

Section: Introductionmentioning

confidence: 99%

CD39/NTPDase-1 expression and activity in human umbilical vein endothelial cells are differentially regulated by leaf extracts from Rubus caesius and Rubus idaeus

Dudzińska

Luzak

Boncler

et al. 2014

Cellular and Molecular Biology Letters

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Many experimental studies have demonstrated the favorable biological activities of plants belonging to the genus Rubus, but little is known of the role of Rubus leaf extracts in the modulation of the surface membrane expression and activity of endothelial apyrase. The aim of this study was to assess the influence of 1–15 μg/ml Rubus extracts on CD39 expression and enzymatic activity, and on the activation (ICAM-1 expression) and viability of human umbilical vein endothelial cells (HUVEC). The polyphenolic contents and antioxidative capacities of extracts from dewberry (R. caesius L.) and raspberry (R. idaeus L.) leaves were also investigated. The techniques applied were flow cytometry (endothelial surface membrane expression of ICAM-1 and CD39), malachite green assay (CD39 activity), HPLC-DAD (quantitative analysis of polyphenolic extract), ABTS, DPPH and FRAP spectrometric assays (antioxidant capacity), and the MTT test (cell viability). Significantly increased CD39 expressions and significantly decreased ATPDase activities were found in the cells treated with 15 μg/ml of either extract compared to the results for the controls. Neither of the extracts affected cell proliferation, but both significantly augmented endothelial cell ICAM-1 expression. The overall antioxidant capacities of the examined extracts remained relatively high and corresponded well to the determined total polyphenol contents. Overall, the results indicate that under in vitro conditions dewberry and raspberry leaf extracts have unfavorable impact on endothelial cells.

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Inhibition of platelet function by an aspirin-insensitive endothelial cell ADPase. Thromboregulation by endothelial cells.

Cited by 167 publications

References 21 publications

Purification, Cloning, Expression, and Mechanism of Action of a Novel Platelet Aggregation Inhibitor from the Salivary Gland of the Blood-sucking Bug, Rhodnius prolixus

Purification, Cloning, Expression, and Mechanism of Action of a Novel Platelet Aggregation Inhibitor from the Salivary Gland of the Blood-sucking Bug, Rhodnius prolixus

Inhibition of carboxypeptidase U (TAFIa) activity improves rt-PA induced thrombolysis in a dog model of coronary artery thrombosis

CD39/NTPDase-1 expression and activity in human umbilical vein endothelial cells are differentially regulated by leaf extracts from Rubus caesius and Rubus idaeus

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