The Ig-ITIM superfamily member PECAM-1 regulates the “outside-in” signaling properties of integrin αIIbβ3 in platelets

Blood ◽  
2005 ◽  
Vol 106 (12) ◽  
pp. 3816-3823 ◽  
Author(s):  
Janet L. Wee ◽  
Denise E. Jackson
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Calcium Ionophore ◽  
Adenosine Diphosphate ◽  
Free Calcium ◽  
Altered Expression ◽  
Integrin Αiibβ3 ◽  
Glycoprotein Vi ◽  
Normal Platelet

Previous studies have implicated the immunoglobulin (Ig)–immunoreceptor tyrosine–based inhibitory motif (ITIM) superfamily member platelet endothelial cell adhesion molecule-1 (PECAM-1) in the regulation of integrin function. While PECAM-1 has been demonstrated to play a role as an inhibitory coreceptor of immunoreceptor tyrosine–based activation motif (ITAM)–associated Fcγ receptor IIa (FcγRIIa) and glycoprotein VI (GPVI)/FcR γ-chain signaling pathways in platelets, its physiologic role in integrin αIIbβ3–mediated platelet function is unclear. In this study, we investigate the functional importance of PECAM-1 in murine platelets. Using PECAM-1–deficient mice, we show that the platelets have impaired “outside-in” integrin αIIbβ3 signaling with impaired platelet spreading on fibrinogen, failure to retract fibrin clots in vitro, and reduced tyrosine phosphorylation of focal adhesion kinase p125 (125FAK) following integrin αIIbβ3–mediated platelet aggregation. This functional integrin αIIbβ3 defect could not be attributed to altered expression of integrin αIIbβ3. PECAM-1–/– platelets displayed normal platelet alpha granule secretion, normal platelet aggregation to protease-activated receptor-4 (PAR-4), adenosine diphosphate (ADP), and calcium ionophore, and static platelet adhesion. In addition, PECAM-1–/– platelets displayed normal “inside-out” integrin αIIbβ3 signaling properties as demonstrated by normal agonist-induced binding of soluble fluoroscein isothiocyanate (FITC)–fibrinogen, JON/A antibody binding, and increases in cytosolic-free calcium and inositol (1,4,5)P3 triphosphate (IP3) levels. This study provides direct evidence that PECAM-1 is essential for normal integrin αIIbβ3–mediated platelet function and that disruption of PECAM-1 induced a moderate “outsidein” integrin αIIbβ3 signaling defect.

The tetraspanin superfamily member CD151 regulates outside-in integrin αIIbβ3 signaling and platelet function

Blood ◽  
2004 ◽  
Vol 104 (8) ◽  
pp. 2368-2375 ◽  
Author(s):  
Lai-Man Lau ◽  
Janet L. Wee ◽  
Mark D. Wright ◽  
Gregory W. Moseley ◽  
P. Mark Hogarth ◽  
...  
Keyword(s):  
Platelet Function ◽  
Fluorescein Isothiocyanate ◽  
Dense Granule ◽  
Free Calcium ◽  
Clot Retraction ◽  
Altered Expression ◽  
Integrin Αiibβ3 ◽  
Normal Platelet ◽  
Granule Secretion

Abstract The tetraspanin family member CD151 forms complexes with integrins and regulates cell adhesion and migration. While CD151 is highly expressed in megakaryocytes and to a lesser extent in platelets, its physiologic role in platelets is unclear. In this study, we investigate the physical and functional importance of CD151 in murine platelets. Immunoprecipitation/Western blot studies reveal a constitutive physical association of CD151 with integrin αIIbβ3 complex under strong detergent conditions. Using CD151-deficient mice, we show that the platelets have impaired “outside-in” integrin αIIbβ3 signaling with defective platelet aggregation responses to protease-activated receptor 4 (PAR-4) agonist peptide, collagen, and adenosine diphosphate (ADP); impaired platelet spreading on fibrinogen; and delayed kinetics of clot retraction in vitro. This functional integrin αIIbβ3 defect could not be attributed to altered expression of integrin αIIbβ3. CD151–/– platelets displayed normal platelet alpha granule secretion, dense granule secretion, and static platelet adhesion. In addition, CD151–/– platelets displayed normal “inside-out” integrin αIIbβ3 signaling properties as demonstrated by normal agonist-induced binding of soluble fluorescein isothiocyanate (FITC)–fibrinogen, JON/A antibody binding, and increases in cytosolic-free calcium and inositol 1,4,5 triphosphate (IP3) levels. This study provides the first direct evidence that CD151 is essential for normal platelet function and that disruption of CD151 induced a moderate outside-in integrin αIIbβ3 signaling defect.

Inhibition of Platelet Function by Antiarrhythmic Drugs, Verapamil and Disopyramide

1982 ◽  
Vol 47 (02) ◽  
pp. 150-153 ◽  
Author(s):  
P Han ◽  
C Boatwright ◽  
N G Ardlie
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Antiarrhythmic Drugs ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Second Phase ◽  
Ionophore A23187 ◽  
High Concentrations ◽  
Artery Disease

SummaryVarious cardiovascular drugs such as nitrates and propranolol, used in the treatment of coronary artery disease have been shown to have an antiplatelet effect. We have studied the in vitro effects of two antiarrhythmic drugs, verapamil and disopyramide, and have shown their inhibitory effect on platelet function. Verapamil, a calcium channel blocker, inhibited the second phase of platelet aggregation induced by adenosine diphosphate (ADP) and inhibited aggregation induced by collagen. Disopyramide similarly inhibited the second phase of platelet aggregation caused by ADP and aggregation induced by collagen. Either drug in synergism with propranolol inhibited ADP or collagen-induced platelet aggregation. Disopyramide at high concentrations inhibited arachidonic add whereas verapamil was without effect. Verapamil, but not disopyramide, inhibited aggregation induced by the ionophore A23187.

Impaired Platelet Function in Sept8-Deficient Mice In Vitro

2020 ◽  
Author(s):  
Kerstin Jurk ◽  
Katharina Neubauer ◽  
Victoria Petermann ◽  
Elena Kumm ◽  
Barbara Zieger
Keyword(s):  
Platelet Function ◽  
Thrombin Generation ◽  
Human Platelets ◽  
Platelet Surface ◽  
Integrin Αiibβ3 ◽  
Glycoprotein Vi ◽  
Fibrinogen Receptor ◽  
Static Conditions ◽  
The Impact

AbstractSeptins (Septs) are a widely expressed protein family of 13 mammalian members, recognized as a unique component of the cytoskeleton. In human platelets, we previously described that SEPT4 and SEPT8 are localized surrounding α-granules and move to the platelet surface after activation, indicating a possible role in platelet physiology. In this study, we investigated the impact of Sept8 on platelet function in vitro using Sept8-deficient mouse platelets. Deletion of Sept8 in mouse platelets caused a pronounced defect in activation of the fibrinogen receptor integrin αIIbβ3, α-granule exocytosis, and aggregation, especially in response to the glycoprotein VI agonist convulxin. In contrast, δ-granule and lysosome exocytosis of Sept8-deficient platelets was comparable to wild-type platelets. Sept8-deficient platelet binding to immobilized fibrinogen under static conditions was diminished and spreading delayed. The procoagulant activity of Sept8-deficient platelets was reduced in response to convulxin as determined by lactadherin binding. Also thrombin generation was decreased relative to controls. Thus, Sept8 is required for efficient integrin αIIbβ3 activation, α-granule release, platelet aggregation, and contributes to platelet-dependent thrombin generation. These results revealed Sept8 as a modulator of distinct platelet functions involved in primary and secondary hemostatic processes.

scholarly journals "Impotent" Platelets in Albinos With Prolonged Bleeding Times

Blood ◽  
1972 ◽  
Vol 39 (4) ◽  
pp. 490-499 ◽  
Author(s):  
Harold M. Maurer ◽  
James A. Wolff ◽  
Sue Buckingham ◽  
Arthur R. Spielvogel
Keyword(s):  
Platelet Aggregation ◽  
Adenosine Diphosphate ◽  
Bleeding Tendency ◽  
Prolonged Bleeding ◽  
Prolonged Bleeding Time ◽  
Normal Platelet ◽  
Tryptophan Metabolites ◽  
History Of

Abstract Functional, biochemical, and morphologic platelet abnormalities are reported in four children with the syndrome of albinism, mild bleeding tendency, prolonged bleeding time, and normal platelet count. In these children, primary platelet aggregation with adenosine diphosphate occurred normally, but secondary aggregation was impaired. Collagen and norepinephrine produced almost no platelet aggregation. Platelet content of serotonin (5-HT) was markedly reduced, and uptake and retention of 5-HT by the platelets in vivo and in vitro was poor. In one child who was given a tryptophan load, urinary tryptophan metabolites were normal, suggesting that there was no evidence of a block in the 5-HT synthetic pathway in the gastrointestinal tract. Electron microscopy revealed an absence of densely osmophilic granules in 5-HT poor platelets. Platelets from other albinos with no history of bleeding contained normal amounts of 5-HT and densely osmophilic granules.

Effects of Lead Acetate on Platelet Aggregation, Ultrastructure and Serotonin Release

1971 ◽  
Vol 26 (03) ◽  
pp. 455-466 ◽  
Author(s):  
R. B Davis ◽  
G. C Holtz
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Lead Acetate ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Human Platelets ◽  
Serotonin Release ◽  
Aggregation Of Platelets

SummaryThe effects of lead on blood platelet function and ultrastructure have been investigated. Lead acetate was injected intravenously in 27 rats and was added to rat and human platelet rich plasma in vitro. In vitro studies showed that concentrations of 2.5 × 10-3 M lead acetate reduced or blocked aggregation of rat and human platelets by adenosine diphosphate, collagen, and thrombin. Radioactive serotonin release from human platelets was inhibited by 10-4 M lead acetate. One hour after the injection of lead, platelet aggregation by thrombin was reduced, but platelet aggregation by adenosine diphosphate and collagen showed little change. Three days after lead, aggregation of platelets by collagen and thrombin was blocked and aggregation by adenosine diphosphate reduced. Thrombocytopenia was present 4 days after intravenous lead acetate. Electron micrographs of platelets showed that the mean number of mitochondria per platelet was increased, whereas alpha granules were reduced. Dense bodies were not significantly changed. Lead acetate affects platelet function in concentrations reported in human bone marrow in lead poisoning, and may relate to the binding of free sulfhydryl groups by lead.

scholarly journals Effect of propranolol on platelet function

Blood ◽  
1977 ◽  
Vol 49 (2) ◽  
pp. 185-196 ◽  
Author(s):  
BB Weksler ◽  
M Gillick ◽  
J Pink
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Direct Action ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Ionophore A23187 ◽  
Atherosclerotic Vascular Disease ◽  
Clot Retraction

Abstract Excessive reactivity of blood platelets may contribute to atherosclerotic vascular disease. Hence drugs which alter platelet function may be protective. Prompted by findings that propranolol therapy normalized hyperactive platelet aggregation in patients with coronary artery disease, we studied propranolol in vitro to assess its action on platelets. At concentrations similar to those achieved in vivo (0.1–1 muM), propranolol raised the thresholds for aggregation of some normal paltelets by adenosine diphosphate (ADP). At higher concentrations (10-50 muM), propranolol abolished the second wave of platelet aggregation induced by ADP and epinephrine, and inhibited aggregation induced by collagen, thrombin, and the ionophore A23187. Propanolol blocked the release of 14C-serotonin from platelets, inhibited platelet adhesion to collagen, and interfered with clot retraction. Propranolol blocked ionophore-induced uptake of 45Ca by platelets. Inhibition appeared unrelated to beta-adrenergic blockage, as d(+) propranolol (which lacks beta-blocking activity) was equipotent with 1(-) propranolol. Moreover, practolol, a beta-blockading drug which is nonlipophilic, did not inhibit platelet function. These studies suggested that propranolol, like local anesthetics, decreased platelet responsiveness by a direct action on the platelet membrane, possibly by interfering with calcium availability. Modulation of platelet function by propranolol may occur at concentrations achieved at usual clinical doses of the drug.

scholarly journals Coenzyme Q10 Attenuates Platelet Integrin αIIbβ3 Outside-in Signaling through Targeting cAMP/PKA Pathway and Inhibits Atherosclerosis

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2423-2423
Author(s):  
Yan Yang ◽  
Xiaohong Ruby Xu ◽  
Heyu Ni ◽  
Liping Ma ◽  
Wenhua Ling ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Clot Retraction ◽  
Integrin Αiibβ3 ◽  
Granule Secretion ◽  
Platelet Spreading ◽  
Pka Pathway ◽  
Inside Out

Abstract Introduction: Platelet integrin αIIbβ3 outside-in signaling is crucial for platelet adhesion and aggregation, and contributes to atherogenesis. Coenzyme Q10 (CoQ10) has been implicated as a protective factor against cardiovascular diseases (CVDs), particularly atherosclerosis. However, whether CoQ10 attenuates atherosclerosis through inhibiting platelet function and αIIbβ3 outside-in signaling is unknown. The aim of this study was to explore whether CoQ10 affects platelet function and αIIbβ3 outside-in signalling and thus inhibiting the progress of atherosclerosis in vivo and the underlying mechanisms in vitro. Methods: In vitro study, The murine platelet rich plasma (PRP) from C57BL/6J wild-type (WT) mice or human PRP and gel-filtered platelets were incubated with different concentrations (1, 10 or 100 μM) of CoQ10 or the vehicle control for 50 min. Platelet aggregation, spreading on fibrinogen (Fg) and clot retraction were determined. In addition, the effects of CoQ10 on platelet integrin αIIbβ3 inside-out signalling (e.g., talin-1 and kindlin-3 binding to integrin β3) were determined by immunoprecipitation, and outside-in signalling (e.g., phosphorylation of sarcoma tyrosine-protein kinase (c-Src), focal adhesion kinase (FAK), and β3 cytoplasmic tail, myosin light chain (MLC)) were determined by Western blotting. The levels of platelet ATP and cAMP were measured by ELISA assays. In vivo study, male homozygous apolipoprotein E-deficient (apoE-/-) mice (C57BL/6 genetic background) were fed either a standard normal AIN-93G diet (NC group), a Western-type diet (HFD group) or a Western-type diet supplemented with CoQ10 (1800 mg/kg diet) (CoQ10 group) for 12 weeks. Platelet aggregation, granule secretion, platelet spreading, clot retraction, integrin αIIbβ3 outside-in signalling, platelet-leukocyte interactions and carotid artery plaque area were also examined. In our randomized, double-blind, placebo-controlled trial, 101 hypercholesterolemic subjects were randomly administrated to 120 mg CoQ10 or placebo daily for 24 weeks. Platelet intracellular CoQ10 levels, platelet aggregation in PRP, platelet platelet factor 4 (PF-4) and C-C motif ligand 5 (CCL5) release, and platelet integrin αIIbβ3 outside-in signalling were also evaluated before and after 24 weeks of intervention. Results: We found that CoQ10 inhibited human and WT mouse platelet aggregation, platelet spreading, granule secretion, and clot retraction in vitro and apoE-/- mice on a high fat diet. CoQ10 also reduced atherosclerosis and platelet-monocyte aggregation in apoE-/- mice. The inhibitory effects of CoQ10 is mediated by attenuated αIIbβ3 outside-in signalling pathway (e.g., attenuation of phosphorylation of c-Src, FAK, and β3 cytoplasmic tail, and MLC in thrombin-activated platelets or platelets exposed to immobilized Fg), which requires up-regulation of the cAMP/PKA pathway, where CoQ10 inhibited phosphodiesterase 3A activity and activated the A2A adenosine receptor. However, CoQ10 did not affect platelet integrin αIIbβ3 inside-out signalling pathway, platelet cellular ATP, or platelet apoptosis (the mitochondrial membrane potential and phosphatidylserine exposure). Moreover, our clinical trial in dyslipidemic patients demonstrated that CoQ10 supplementation attenuated platelet aggregation, which was positively correlated with the increased platelet CoQ10 concentrations, inhibited αIIbβ3 outside-in signalling and decreased platelet PF-4 and CCL5 secretion. Conclusions: We present new data to suggest that CoQ10 plays a novel role in attenuating platelet function and integrin αIIbβ3 outside-in signalling though targeting cAMP/PKA signalling cascade and thus inhibiting the progress of atherosclerosis. CoQ10 is therefore a promising agent for the prevention and/or treatment for cardiovascular disease. Disclosures No relevant conflicts of interest to declare.

Inhibitory effects of H2-receptor antagonists on platelet function in vitro

1999 ◽  
Vol 18 (8) ◽  
pp. 487-492 ◽  
Author(s):  
K Nakamura ◽  
H Kariyazono ◽  
T Shinkawal ◽  
T Yamaguchi ◽  
T Yamashita ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Chemical Structure ◽  
Adenosine Diphosphate ◽  
Imidazole Ring ◽  
Inhibitory Effects ◽  
Receptor Antagonists ◽  
Induced Aggregation

1 To evaluate in vitro inhibitory effects of four types of histamine H2-receptor antagonist (H2-receptor antagonists), famotidine, roxatidine, cimetidine and ranitidine, on platelet function, we examined aggregating potency and P-selectin levels with agonist-induced aggregation. Ranitidine and cimetidine inhibited, in concentration of 0.35 mM, the secondary aggregation induced by 5 pM adenosine diphosphate (ADP), the aggregation induced by 1,g/mL collagen and 3 gM arachidonic acid. All of H2-receptor antagonists inhibited, in concentration of 1.4 mm, the aggregation induced by ADP, collagen and arachidonic acid. Ranitidine and cimetidine reduced markedly, in same concentration, P-selectin levels after induction of aggregation by 5 gm ADP, 1 ig/xmL collagen and 3 gM arachidonic acid. When classified by the strength of inhibitory action, ranitidine and cimetidine were strong, followed by famotidine and roxatidine. 2 It is considered that inhibitory effects of H.-receptor antagonists on platelet function are weaker than those of acetylsalicylic acid (ASA), since ASA inhibited platelet aggregation in concentration of 100 MM. 3 No relationship was observed between inhibitory effects of H2-receptor antagonists on platelet aggregation induced by above agonists and the presence or absence of imidazole ring in the chemical structure.

In Vitro Effects of Dihomo-γLinolenic Acid (DHLA) on Normal and Diabetic Platelet Function

1979 ◽  
Author(s):  
M. Zuzel ◽  
P.B.A. Kernoff ◽  
A.L. Willis ◽  
R.C. Paton ◽  
G.P. McNicol
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Platelet Rich Plasma ◽  
In Vitro Tests ◽  
Diabetic Patients ◽  
Normal Platelet ◽  
In Vitro Effects ◽  
Kinetics Of ◽  
Primary Platelet

DHLA causes a general inhibition of platelet reactions in standard in vitro tests of platelet function. Significantly more DHLA is required for the 50% inhibition (ID 50) of diabetic when compared to normal platelet reactions (Kernoff et al. Thrombosis & Haemostasis 38, 194, 1977). To investigate the cause of this difference we have studied kinetics of ADP-induced primary platelet aggregation, its inhibition by DHLA, and the formation of malondialdehyde (MDA) in the presence of DHLA in platelet-rich plasma of six healthy subjects and six diabetic patients with advanced microangiopathy. The results showed a significantly lower Km (ADP) for platelet aggregation in the diabetic group compared to normal. The (DHLA) of the competitive component of inhibition of platelet aggregation (prostaglandin production-mediated) was not significantly different In the two groups. Also, amounts of MDA formed in diabetic and normal PRP in the presence of DHLA were not significantly different. We conclude that the apparent low susceptibility of diabetic platelets to inhibition by DHLA might be a result of a primary hyper-reactivity of these platelets due to a cause other than an abnormality of the platelet PG production pathway.

scholarly journals Impairment in Platelet Aggregation in Congenital Heart Disease

Blood ◽  
1972 ◽  
Vol 40 (2) ◽  
pp. 207-216 ◽  
Author(s):  
Harold M. Maurer ◽  
Carolyn M. McCue ◽  
Joyce Caul ◽  
W. J. S. Still
Keyword(s):  
Congenital Heart Disease ◽  
Heart Disease ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Congenital Heart ◽  
Adenosine Diphosphate ◽  
Normal Platelet ◽  
Acquired Heart Disease ◽  
High Concentrations ◽  
Platelet Content

Abstract Platelet function and coagulation studies were performed on 65 children with congenital heart disease (CHD) and five wtih acquired heart disease, varying in age from 2 wk to 17 yr. Approximately 11% of the children with CHD had mild bleeding symptoms, and 9% had prolonged bleeding times, despite normal platelet counts. In 14 of 37 children (37.8%) with cyanotic CHD and four of 28 (14.3%) with the acyanotic variety, platelet aggregation by adenosine diphosphate (ADP), noradrenalin, and connective tissue suspension was impaired. The possibility of a platelet inhibitory factor in plasma was unlikely. Platelet content of ADP was normal, and high concentrations of exogenous ADP produced an improvement in aggregation, suggesting that the disturbance may be due to defective release of intrinsic ADP from the platelets. Impairment in aggregation was correlated with the severity of hypoxemia and polycythemia in cyanotic patients. Coagulation data did not support the concept that disseminated intravascular coagulation is a frequently associated finding in cyanotic CHD. Our findings reveal a disturbance in platelet function, until now, not commonly associated with CHD.

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