251
|
Abstract
This review summarizes recent developments in our understanding of the molecular basis of platelet activation by two distinct types of surface receptor, the immunoglobulin GPVI, and the integrin alphaIIb beta3 (also known as GPIIbIIIa). These two classes of receptor signal through similar yet distinct tyrosine kinase-based signaling cascades leading to activation of phospholipase C gamma2. The significance of these signaling cascades in platelet adhesion and platelet aggregation at arterial rates of shear is discussed.
Collapse
Affiliation(s)
- S P Watson
- Division of Medical Sciences, Centre for Cardiovascular Sciences, Institute of Biomedical Research, The Medical School, University of Birmingham, Birmingham, UK.
| | | | | | | |
Collapse
|
252
|
Kaneko M, Takafuta T, Cuyun-Lira O, Satoh K, Arai M, Yatomi Y, Ozaki Y. Evaluation of platelet function under high shear condition in the small-sized collagen bead column. ACTA ACUST UNITED AC 2005; 146:64-75. [PMID: 16099236 DOI: 10.1016/j.lab.2005.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Revised: 03/14/2005] [Accepted: 04/04/2005] [Indexed: 11/26/2022]
Abstract
We previously reported that platelet retention rates as measured with collagen-coated bead columns (the conventional column) reflect the processes of platelet adhesion and aggregation under low shear stress, and that this system could serve as an easy-to-use platelet aggregometry. With this column, platelet glycoprotein (GP) VI and GPIIb/IIIa, but not the GPIb-von Willebrand factor (VWF) interaction, play major roles in platelet activation. To develop a system that can better reflect the GPIb-VWF interaction under high shear stress, we designed a column containing small-sized beads (125-212 microm) coated with porcine collagen type I. As expected, the GPIb-VWF interaction played a crucial role in platelet retention rates at higher flow rates. Adenosine 5'-diphosphate, but not thromboxane A2, appears to support platelet activation in this system. The platelet retention rates among healthy individuals with the new columns are in the range wider than the conventional columns, and this diversity could be attributed to the broad range of the VWF antigen and/or its activity. It is suggested that this new column can serve as an easy-to-use method for evaluating the VWF antigen levels and its activity and for monitoring patients with thrombotic or bleeding disorders related to the VWF-GPIb interaction.
Collapse
Affiliation(s)
- Makoto Kaneko
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Shimokato, Tamaho, Nakakoma, Yamanashi, Japan
| | | | | | | | | | | | | |
Collapse
|
253
|
Garcia A, Quinton TM, Dorsam RT, Kunapuli SP. Src family kinase-mediated and Erk-mediated thromboxane A2 generation are essential for VWF/GPIb-induced fibrinogen receptor activation in human platelets. Blood 2005; 106:3410-4. [PMID: 16020504 PMCID: PMC1895051 DOI: 10.1182/blood-2005-05-1933] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The binding of von Willebrand factor (VWF) to the platelet membrane glycoprotein Ib-IX (GPIb-IX) results in platelet activation. In this study, we sought to clarify previous conflicting reports and to elucidate the mechanism of activation and the precise role of extracellular signal-regulated kinase (Erk) in VWF-induced platelet activation. Erk2 is activated in platelets on stimulation with VWF/ristocetin in a time-dependent manner. VWF-induced Erk2 phosphorylation and thromboxane A2 (TXA2) release were completely blocked by PP2, an Src family kinase inhibitor, suggesting that Erk is downstream of Src family kinases. U73122, a phospholipase C inhibitor, also abolished TXA2 generation and Erk phosphorylation. Although VWF fostered the agglutination of platelets regardless of any additional treatment, the inhibition of mitogen-activated protein kinase kinase (MEK) with U0126 abolished VWF-induced platelet aggregation and thromboxane production in non-aspirin-treated washed platelets. However, in platelets treated with aspirin, VWF failed to cause any aggregation. Thus, we conclude that VWF stimulation of platelets results in phospholipase A2 activation through Erk stimulation and that Src family kinases and phospholipase C play essential roles in this event. We further conclude that VWF-induced platelet aggregation does not directly depend on Erk activation but has an absolute requirement for Src/Erk-mediated TXA2 generation.
Collapse
Affiliation(s)
- Analia Garcia
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | | | | | | |
Collapse
|
254
|
Prévost N, Woulfe DS, Jiang H, Stalker TJ, Marchese P, Ruggeri ZM, Brass LF. Eph kinases and ephrins support thrombus growth and stability by regulating integrin outside-in signaling in platelets. Proc Natl Acad Sci U S A 2005; 102:9820-5. [PMID: 15994237 PMCID: PMC1174973 DOI: 10.1073/pnas.0404065102] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of activated platelets to adhere to each other at sites of vascular injury depends on the integrin alpha(IIb)beta(3). However, as aggregation continues, other signaling and adhesion molecules can contribute as well. We have previously shown that human platelets express on their surface the Eph receptor kinases EphA4 and EphB1 and the Eph kinase ligand ephrinB1. We now show that EphA4 is physically associated with alpha(IIb)beta(3) in resting platelets, increases its surface expression when platelets are activated, and colocalizes with alpha(IIb)beta(3) at sites of contact between platelets. We also show that Eph/ephrin interactions can support the stable accumulation of platelets on collagen under flow and contribute to postengagement "outside-in" signaling through alpha(IIb)beta(3) by stabilizing platelet aggregates and facilitating tyrosine phosphorylation of the beta(3) cytoplasmic domain. beta(3) phosphorylation allows myosin to bind to alpha(IIb)beta(3) and clot retraction to occur. The data support a model in which the onset of aggregation permits Eph/ephrin interactions to occur, after which signaling downstream from ephrinB1 and its receptors favors continued growth and stability of the thrombus by several mechanisms, including positive effects on outside-in signaling through alpha(IIb)beta(3).
Collapse
Affiliation(s)
- Nicolas Prévost
- Department of Medicine, and Center for Experimental Therapeutics, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | |
Collapse
|
255
|
Abstract
Platelets perform a central role in haemostasis and thrombosis. They adhere to subendothelial collagens exposed at sites of blood vessel injury via the glycoprotein (GP) Ib-V-IX receptor complex, GPVI and integrin alpha(2)beta(1). These receptors perform distinct functions in the regulation of cell signalling involving non-receptor tyrosine kinases (e.g. Src, Fyn, Lyn, Syk and Btk), adaptor proteins, phospholipase C and lipid kinases such as phosphoinositide 3-kinase. They are also coupled to an increase in cytosolic calcium levels and protein kinase C activation, leading to the secretion of paracrine/autocrine platelet factors and an increase in integrin receptor affinities. Through the binding of plasma fibrinogen and von Willebrand Factor to integrin alpha(IIb)beta(3), a platelet thrombus is formed. Although increasing evidence indicates that each of the adhesion receptors GPIb-V-IX and GPVI and integrins alpha(2)beta(1) and alpha(IIb)beta(3) contribute to the signalling that regulates this process, the individual roles of each are only beginning to be dissected. By contrast, adhesion receptor signalling through platelet endothelial cell adhesion molecule 1 (PECAM-1) is implicated in the inhibition of platelet function and thrombus formation in the healthy circulation. Recent studies indicate that understanding of platelet adhesion signalling mechanisms might enable the development of new strategies to treat and prevent thrombosis.
Collapse
Affiliation(s)
- Jonathan M Gibbins
- School of Animal and Microbial Sciences, The University of Reading, Whiteknights, PO Box 228, Reading, Berkshire RG6 6AJ, UK.
| |
Collapse
|
256
|
Andrews RK, Berndt MC. Platelet physiology and thrombosis. Thromb Res 2005; 114:447-53. [PMID: 15507277 DOI: 10.1016/j.thromres.2004.07.020] [Citation(s) in RCA: 275] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Revised: 07/16/2004] [Accepted: 07/16/2004] [Indexed: 11/24/2022]
Abstract
Glycoprotein (GP) Ibalpha of the GPIb-IX-V complex and GPVI bind von Willebrand factor (vWF) and collagen, respectively, and are critical for the initial interaction of circulating platelets with the injured vessel wall under high shear conditions. These interactions act together to facilitate stable thrombus formation in vivo. Ligand binding to GPIb-IX-V of the leucine-rich repeat family or GPVI of the immunoglobulin superfamily initiates platelet activation, and inside-out activation of the platelet integrin, alphaIIbbeta3, that binds vWF or fibrinogen and mediates platelet aggregation. The binding site for GPIbalpha on vWF resides in the conserved A1 domain, encompassing the disulfide bond at Cys509-Cys695. This domain may be activated to bind platelet GPIbalpha under shear stress by anchoring of the downstream A3 domain to collagen and conformational distortion of the intervening A2 domain. The N-terminal, 282 residues, of GPIbalpha contains the binding site for vWF-A1, as well as the conserved A-type domain of the leukocyte integrin alphaMbeta2 (alphaM I domain) and P-selectin expressed on activated platelets or endothelial cells. Endothelial P-selectin also supports surface expression of vWF multimers, enabling platelet vessel wall interaction by at least two mechanisms. Recent evidence suggests GPVI that binds collagen, and GPIb-IX-V that binds collagen-bound vWF are physically associated on the platelet surface. This review will focus on the structure-function of primary platelet adhesion receptors, GPIb-IX-V and GPVI, and how they act together to regulate platelet thrombus formation in pathophysiology.
Collapse
Affiliation(s)
- Robert K Andrews
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168, Australia.
| | | |
Collapse
|
257
|
|
258
|
Heger M, Beek J, Stenback K, Faber D, van Gemert M, Ince C. Darkfield orthogonal polarized spectral imaging for studying endovascular laser-tissue interactions in vivo - a preliminary study. OPTICS EXPRESS 2005; 13:702-15. [PMID: 19494931 DOI: 10.1364/opex.13.000702] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Due to the limited number of suitable intravital microscopy techniques, relatively little is known about the opto-thermal (endo)vascular responses to selective photothermolysis, used as a default treatment modality for superficial vascular anomalies such as port wine stains, telangiectasias, and hemangiomas. In this preliminary study we present a novel microscopy technique for studying (endo)vascular laser-tissue interactions in vivo, in which conventional orthogonal polarized spectral (OPS) imaging is combined with darkfield (DF) illumination. DFOPS imaging of rat mesenteric vasculature irradiated at increasing powers revealed the following (tissular) responses: formation of translucent aggregates, retrograde flow, gradual and immediate hemostasis, reinstatement of flow, vessel disappearance, and perivascular collagen damage. DFOPS imaging therefore constitutes a useful tool for examining (endo)vascular events following selective photothermolysis.
Collapse
|
259
|
Abstract
Thrombotic diseases such as heart attack and stroke remain a major health concern in the Western world despite existing anti-thrombotic drugs. Current studies are revealing structure-function relationships of primary platelet adhesion receptors mediating adhesion, activation and aggregation, and the molecular mechanisms underlying platelet thrombus formation. Platelet adhesion is relevant not only to thrombotic disease, but there is increasing evidence of a specific role for platelets in vascular processes such as inflammation and atherogenesis. This review focuses on recent advances in understanding the molecular basis for platelet thrombus formation, in particular the receptors, glycoprotein (GP)Ib-IX-V and GPVI, that initiate platelet adhesion and activation at high shear stress.
Collapse
Affiliation(s)
- Jana Yip
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | | | | | | |
Collapse
|
260
|
Jagadeeswaran P, Gregory M, Day K, Cykowski M, Thattaliyath B. Zebrafish: a genetic model for hemostasis and thrombosis. J Thromb Haemost 2005; 3:46-53. [PMID: 15634265 DOI: 10.1111/j.1538-7836.2004.00999.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Here we review the zebrafish hemostatic system, its relevance to mammalian hemostasis, and its efficacy as a vertebrate genetic model to further the understanding of hemostasis and thrombosis.
Collapse
Affiliation(s)
- P Jagadeeswaran
- Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
| | | | | | | | | |
Collapse
|
261
|
Guglielmone HA, Agnese AM, Núñez Montoya SC, Cabrera JL. Inhibitory effects of sulphated flavonoids isolated from Flaveria bidentis on platelet aggregation. Thromb Res 2005; 115:495-502. [PMID: 15792681 DOI: 10.1016/j.thromres.2004.11.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 11/15/2004] [Accepted: 11/16/2004] [Indexed: 10/26/2022]
Abstract
Flaveria bidentis is a plant species that has as major constituents sulphated flavonoids in the highest degree of sulphatation. Among them, quercetin 3,7,3',4'-tetrasulphate (QTS) and quercetin 3-acetyl-7,3',4'-trisulphate (ATS) are the most important constituents. Both showed anticoagulant properties. The objective of the present study was to evaluate the effects of these flavonoids on human platelet aggregation in comparison with the well-known inhibitor quercetin (Qc) by using several agonists. Platelet-rich plasma (PRP) or washed human platelets (WP) were incubated with different concentrations of the flavonoids to be tested (1 to 1000 microM, final concentration), and the platelet aggregation was induced by using adenosine 5'-diphosphate (ADP), epinephrine (EP), collagen, arachidonic acid (AA) and ristocetin as agonists. QTS (500 microM) and Qc (250 microM) markedly inhibited platelet aggregation with all the aggregant agents, except ristocetin, whereas ATS (1000 microM) showed only slight antiplatelet effects. In addition, QTS and Qc antagonized the aggregation of PRP or WP induced by U-46619, a mimetic thromboxane A2 (TxA2) receptor agonist. Challenged with collagen or arachidonic acid, the thromboxane B2 (TxB2) formation was also inhibited by the flavonoids, mainly by QTS and Qc, in WP. These results demonstrate that QTS and in minor extension ATS induce a deleterious effect on the production of TxA2, as judged by TxB2 formation, in stimulated WP and a marked interference on the TxA2 receptor according to the profile of inhibition of the agonist-induced platelet aggregation when using ADP, EP, AA and collagen and confirmed with U-46619.
Collapse
Affiliation(s)
- Hugo A Guglielmone
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | | | | | | |
Collapse
|
262
|
Functional expression of human and mouse P2Y12 receptors in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2004; 324:171-7. [PMID: 15464998 DOI: 10.1016/j.bbrc.2004.09.034] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Indexed: 11/18/2022]
Abstract
DNA sequences encoding the murine ortholog of the human P2Y12 receptor were cloned. The human and mouse P2Y12 receptors were expressed in a yeast cell-based GPCR expression technology containing chimeric yeast Galpha protein (Gpa1) constructs in which the 5 C-terminal amino acids were identical to corresponding sequences from mammalian Galphai/o proteins. LacZ reporter gene assays of agonist-induced activation of the G protein-coupled mating signal transduction pathway revealed murine P2Y12 functional pharmacological properties that closely resembled those exhibited by the human P2Y12 receptor. In NIH3T3 cells, the mouse P2Y12 stimulated calcium uptake monitored in FLIPR via coupling to a Galphaq/i3 chimeric protein. Murine P2Y12 mRNA was expressed at high levels in the brain and at lower levels in a variety of peripheral tissues. In situ hybridization analysis indicated glia-specific expression within the brain.
Collapse
|
263
|
Lu D, Mahmood A, Goussev A, Qu C, Zhang ZG, Chopp M. Delayed Thrombosis after Traumatic Brain Injury in Rats. J Neurotrauma 2004; 21:1756-66. [PMID: 15684767 DOI: 10.1089/neu.2004.21.1756] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Secondary thrombosis may contribute to cerebral ischemia caused by traumatic brain injury (TBI). In this study, we sought to investigate the temporal and spatial profiles of intravascular thrombosis and to evaluate the effect of atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitor, on thrombosis after TBI. Young male Wistar rats weighing 350-400 g were subjected to controlled cortical impact injury, and were sacrificed at 1 and 4 h, and 1, 3, 8, and 15 days after TBI (5 rats/time point), respectively. For the evaluation of the effects of atorvastatin on intravascular thrombosis, rats were subjected to TBI, and subsequently atorvastatin (1 mg/kg) was orally administered starting 1 day after TBI and then daily until sacrifice at 3, 8, and 15 days after TBI (5 rats/time point). Before sacrifice of animals, blood was withdrawn and employed for the measurement of von Willibrand factor and platelet activity using enzyme-linked immunoabsorbant assay (ELISA). Brain tissues were prepared for histological analysis. The data show that (1) delayed thrombosis is present in the lesion boundary zone and in the hippocampal CA3 region, starting at 1-4 h, peaking at 1-3 days, and then declining at 8 and 15 days after TBI; (2) intravascular thrombosis also occurs in the other areas of cortex, striatum, and corpus callosum, but with a scattered distribution; (3) delayed thrombi are composed of platelets, fibrin, and vWF; and (4) reduction of the plasma vWF level and platelet activity by atorvastatin decreases delayed thrombosis after TBI. These data suggest that atorvastatin reduces intravascular thrombosis attributed to hemostatic disturbances caused by TBI.
Collapse
Affiliation(s)
- Dunyue Lu
- Department of Neurosurgery, Henry Ford Health Sciences Center, Detroit, Michigan 48202, USA
| | | | | | | | | | | |
Collapse
|
264
|
Canobbio I, Balduini C, Torti M. Signalling through the platelet glycoprotein Ib-V–IX complex. Cell Signal 2004; 16:1329-44. [PMID: 15381249 DOI: 10.1016/j.cellsig.2004.05.008] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Accepted: 05/12/2004] [Indexed: 11/16/2022]
Abstract
The glycoprotein Ib-V-IX is one of the major adhesive receptors expressed on the surface of circulating platelets. It is composed of four different polypeptides-GPIbalpha, GPIbbeta, GPIX, and GPV-and represents a multifunctional receptor able to interact with a number of ligands, including the adhesive protein von Willebrand factor, the coagulation factors thrombin, factors XI and XII, and the membrane glycoproteins P-selectin and Mac-1. Interaction of GPIb-V-IX with the subendothelial von Willebrand factor is essential for primary haemostasis, as it initiates platelet adhesion to the subendothelial matrix at the sites of vascular injury even under high flow conditions. Upon interaction with von Willebrand factor, GPIb-V-IX initiates transmembrane signalling events for platelet activation, which eventually result in integrin alpha(IIb)beta(3) stimulation and platelet aggregation. The investigation of the biochemical mechanisms for platelet activation by GPIb-V-IX has attracted increasing attention during the last years. This review will describe and discuss recent findings that have provided new insights into the events underlying GPIb-V-IX transmembrane signalling. In particular, it will summarise basic concepts on the structure of this receptor, extracellular ligands, and intracellular interactors potentially involved in transmembrane signalling. The recently suggested role of membrane Fc receptors in GPIb-V-IX-initiated platelet activation will also be discussed, along with the involvement of lipid metabolising enzymes, tyrosine kinases, and the cytoskeleton in the crosstalk between GPIb-V-IX and integrin alpha(IIb)beta(3).
Collapse
Affiliation(s)
- Ilaria Canobbio
- Center of Excellence for Applied Biology, Department of Biochemistry, University of Pavia, via Bassi 21, Pavia 27100, Italy
| | | | | |
Collapse
|
265
|
Williams RH, Nollert MU. Platelet-derived NO slows thrombus growth on a collagen type III surface. Thromb J 2004; 2:11. [PMID: 15544706 PMCID: PMC535342 DOI: 10.1186/1477-9560-2-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Accepted: 11/15/2004] [Indexed: 11/10/2022] Open
Abstract
Nitric oxide (NO) is a free radical that plays an important role in modulating platelet adhesion and aggregation. Platelets are a source of vascular NO, but since erythrocytes avidly scavenge NO, the functional significance of platelet-derived NO is not clear. Our purpose was to determine if NO from platelets affects platelet thrombus formation in the presence of anticoagulated whole blood in an in vitro parallel plate flow system. We studied platelet adhesion and aggregation on a collagen type III surface in the presence of physiologically relevant fluid mechanical shear stress. We found that certain receptor mediated agonists (insulin and isoproterenol) caused a concentration dependent reduction in thrombus formation at a shear rate of 1000 s-1. This effect was mediated by NO since it was abolished in the presence of the NO inhibitor L-nitro-arginine-methyl-ester (L-NAME). As expected, at venous levels of shear rate (100 s-1) neither of the agonists had any effect on thrombus formation since platelet adhesion does not depend on activation at these low levels of shear. Interestingly, at a shear rate of 2000 s-1 the addition of L-NAME caused an increase in platelet coverage suggesting that shear, by itself, induces NO production by platelets. This is the first demonstration of shear stress causing platelets to produce an inhibitor of platelet activation. These results demonstrate that the development of a platelet thrombus is regulated in a complex way and that platelets produce functionally significant amounts of NO even in the presence of whole blood.
Collapse
Affiliation(s)
- Robert H Williams
- University of Oklahoma, School of Chemical Engineering and Material Science, 100 East Boyd, Norman, OK 73019, USA
| | - Matthias U Nollert
- University of Oklahoma, School of Chemical Engineering and Material Science, 100 East Boyd, Norman, OK 73019, USA
| |
Collapse
|
266
|
Moers A, Wettschureck N, Grüner S, Nieswandt B, Offermanns S. Unresponsiveness of Platelets Lacking Both Gαq and Gα13. J Biol Chem 2004; 279:45354-9. [PMID: 15326177 DOI: 10.1074/jbc.m408962200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The diffusible platelet stimuli ADP and thromboxane A(2) activate multiple G protein-mediated signaling pathways and function as important secondary mediators of platelet activation as they are released from activated platelets. Because they can also increase their own formation and release, their effects are amplified; eventually, all major G protein-mediated signaling pathways are activated. The multiple positive feedback mechanisms operating during platelet activation have obscured the exact analysis of the roles individual G protein-mediated signaling pathways play during the platelet activation process. In this report, we show that platelets lacking G(q) and G(13) are completely unresponsive to diffusible stimuli such as ADP, thromboxane A(2), or thrombin, even when applied at very high concentrations in combination, whereas all stimuli are able to induce platelet aggregation, shape change, and RhoA activation in platelets lacking only one Galpha subunit. This shows that G(q) or G(13) is required to induce some platelet activation, whereas the activation of G(i)-mediated signaling alone is not sufficient to induceactivation of mouse platelets. In addition, platelets lacking Galpha(q) and Galpha(13) adhered normally to collagen under high shearbut did not aggregate any more in response to collagen, indicating that collagen-induced platelet activation but not platelet adhesion requires intact G protein-mediated signaling pathways.
Collapse
Affiliation(s)
- Alexandra Moers
- Pharmakologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | | | | | | | | |
Collapse
|
267
|
McCarty OJT, Zhao Y, Andrew N, Machesky LM, Staunton D, Frampton J, Watson SP. Evaluation of the role of platelet integrins in fibronectin-dependent spreading and adhesion. J Thromb Haemost 2004; 2:1823-33. [PMID: 15456495 DOI: 10.1111/j.1538-7836.2004.00925.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recent studies have shown that platelet adhesion and subsequent aggregation can occur in vivo in the absence of the two principal platelets adhesive ligands, von Willebrand factor and fibrinogen. These results highlight a possible role for fibronectin in supporting thrombus formation. OBJECTIVE AND METHODS To evaluate the platelet integrins and subsequent activation pathways associated with fibronectin-dependent platelet adhesion utilizing both human and murine platelets. RESULTS Platelets can adhere to fibronectin via the integrin alpha(IIb)beta(3), leading to formation of lamellipodia. This is mediated through an interaction with the tenth type III domain in fibronectin. Spreading on fibronectin promotes alpha(IIb)beta(3)-mediated Ca(2+) mobilization and tyrosine phosphorylation of focal adhesion kinase and phospholipase C gamma2. In contrast, studies with blocking antibodies and mice demonstrate that alpha(5)beta(1) and alpha(v)beta(3) support adhesion and promote formation of filopodia but not lamellipodia or tyrosine phosphorylation of these proteins. Further, neither alpha(5)beta(1) nor alpha(v)beta(3) is able to induce formation of lamellipodia in the presence of platelets agonists, such as collagen-related-peptide (CRP). CONCLUSIONS These observations demonstrate that integrins alpha(5)beta(1) and alpha(v)beta(3) support platelet adhesion and the generation of filopodia but that, in contrast to the integrin alpha(IIb)beta(3), are unable to promote formation of lamellipodia.
Collapse
Affiliation(s)
- O J T McCarty
- Centre for Cardiovascular Sciences, The Institute of Biomedical Research, Division of Medical Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | | | | | | | | | | | | |
Collapse
|
268
|
Fleser PS, Nuthakki VK, Malinzak LE, Callahan RE, Seymour ML, Reynolds MM, Merz SI, Meyerhoff ME, Bendick PJ, Zelenock GB, Shanley CJ. Nitric oxide–releasing biopolymers inhibit thrombus formation in a sheep model of arteriovenous bridge grafts. J Vasc Surg 2004; 40:803-11. [PMID: 15472611 DOI: 10.1016/j.jvs.2004.07.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVES Nitric oxide (NO), produced by normal vascular endothelial cells, reduces platelet aggregation and thrombus formation. NO-releasing biopolymers have the potential to prolong vascular graft and stent patency without adverse systemic vasodilation. METHODS 5-mm polyurethane vascular grafts coated with a polymer containing the NO-donor dialkylhexanediamine diazeniumdiolate were implanted for 21 days in a sheep arteriovenous bridge-graft model. RESULTS Eighty percent (4/5) of grafts coated with the NO-releasing polymer remained patent through the 21 day implantation period, compared to fifty percent (2/4) of sham-coated grafts and no (0/3) uncoated grafts. Thrombus-free surface area (+/-SEM) of explanted grafts was significantly increased in NO-donor coated grafts (98.2% +/- 0.9%) compared with sham-coated (79.2% +/- 8.6%) and uncoated (47.2% +/- 5.4%) grafts ( P = .00046). Examination of the graft surface showed no adherent thrombus or platelets and no inflammatory cell infiltration in NO-donor coated grafts, while control grafts showed adherent complex surface thrombus consisting of red blood cells in an amorphous fibrin matrix, as well as significant red blood cell and inflammatory cell infiltration into the graft wall. CONCLUSION In this study we determined that local NO release from the luminal surface of prosthetic vascular grafts can reduce thrombus formation and prolong patency in a model of prosthetic arteriovenous bridge grafts in adult sheep. These findings may translate into improved function and improved primary patency rates in small-diameter prosthetic vascular grafts.
Collapse
Affiliation(s)
- Paul S Fleser
- William Beaumont Hospital, Department of Surgery and Research Institute, Royal Oak, MI 48073, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
269
|
Shim MH, Hoover A, Blake N, Drachman JG, Reems JA. Gene expression profile of primary human CD34+CD38lo cells differentiating along the megakaryocyte lineage. Exp Hematol 2004; 32:638-48. [PMID: 15246160 DOI: 10.1016/j.exphem.2004.04.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2003] [Revised: 04/08/2004] [Accepted: 04/12/2004] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To identify genes involved in megakaryopoiesis, high-density oligonucleotide microarrays were used to compare transcript profiles from undifferentiated CD34+CD38lo cells and culture-derived megakaryocytes (MKs). MATERIALS AND METHODS Megakaryocyte differentiation was achieved in vitro by inducing primary human CD34+CD38lo cells in serum-deprived media supplemented with the cytokine combination of interleukin-3, interleukin-6, stem cell factor, and thrombopoietin for 10 days. Three replicate microarray experiments were performed using hematopoietic cells isolated from three different organ donors and high-density oligonucleotide microarrays. RESULTS Analysis of gene array data resulted in 304 differentially expressed genes (p < or = 0.001, fold change > or = 3). A third of the 25 most highly up-regulated genes were known to participate in hemostasis (z = 6.75), and no genes known to be associated with MKs were among the down-regulated genes. We also found a large proportion of up-regulated transcripts in gene ontology categories of adhesion and receptor activity (85%) and signal transduction activity (68%). At the same time, 70% of genes within transcription factor functions were down-regulated. Confirmatory studies indicated that the array results correlated with mRNA and protein expression levels in primary MKs. CONCLUSION This study provides a global expression profile of human MKs and a list of novel and previously uncharacterized candidate genes that are important components of megakaryopoiesis.
Collapse
Affiliation(s)
- Mi-Hyun Shim
- Puget Sound Blood Center, Seattle, WA 98104, USA.
| | | | | | | | | |
Collapse
|
270
|
Zwartz GJ, Chigaev A, Dwyer DC, Foutz TD, Edwards BS, Sklar LA. Real-time Analysis of Very Late Antigen-4 Affinity Modulation by Shear. J Biol Chem 2004; 279:38277-86. [PMID: 15226304 DOI: 10.1074/jbc.m402944200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Shear promotes endothelial recruitment of leukocytes, cell activation, and transmigration. Mechanical stress on cells caused by shear can induce a rapid integrin conformational change and activation, followed by an increase in binding to the extracellular matrix. The molecular mechanism of increased avidity is unknown. We have shown previously that the affinity of the alpha(4)beta(1) integrin, very late antigen-4 (VLA-4), measured with an LDV-containing small molecule, varies with cellular avidity, measured from cell disaggregation rates. In this study, we measured in real time affinity changes of VLA-4 in response to shear. The resulting affinity was comparable with the state mediated by receptor signaling and corresponded in time with intracellular Ca(2+) responses. Ca(2+) ionophores and N,N'-[1,2-ethanediyl-bis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]]-, bis[(acetyloxy)methyl]ester demonstrate that the affinity regulation of VLA-4 in the presence of shear was related to Ca(2+) signaling. Pertussis toxin treatment implicates G(i) in an unknown pathway that connects shear, Ca(2+) elevation, VLA-4 affinity, and cell avidity.
Collapse
Affiliation(s)
- Gordon J Zwartz
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | | | | | | | | | | |
Collapse
|
271
|
Jin YR, Cho MR, Ryu CK, Chung JH, Yuk DY, Hong JT, Lee KS, Lee JJ, Lee MY, Lim Y, Yun YP. Antiplatelet Activity of J78 (2-Chloro-3-[2′-bromo, 4′-fluoro-phenyl]-amino-8-hydroxy-1,4-naphthoquinone), an Antithrombotic Agent, Is Mediated by Thromboxane (TX) A2 Receptor Blockade with TXA2 Synthase Inhibition and Suppression of Cytosolic Ca2+ Mobilization. J Pharmacol Exp Ther 2004; 312:214-9. [PMID: 15328379 DOI: 10.1124/jpet.104.073718] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously reported that J78 (2-chloro-3-[2'-bromo, 4'-fluoro-phenyl]-amino-8-hydroxy-1,4-naphthoquinone), a newly synthesized 1,4-naphthoquinone derivative, exhibited a potent antithrombotic effect, which might be due to antiplatelet rather than anticoagulation activity. In the present study, possible anti-platelet mechanism of J78 was investigated. J78 concentration-dependently inhibited rabbit platelet aggregation induced by collagen (10 microg/ml), thrombin (0.05 U/ml), arachidonic acid (100 microM), and U46619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin F(2); 1 microM), a thromboxane (TX) A(2) mimic, with IC(50) values of 0.32 +/- 0.01, 0.44 +/- 0.02, 0.50 +/- 0.04, and 0.36 +/- 0.02 microM, respectively. J78 also produced a shift to the right of the concentration-response curve of U46619, indicating an antagonistic effect on the TXA(2) receptor. J78 concentration-dependently inhibited collagen-induced arachidonic acid liberation. In addition, J78 potently suppressed TXA(2) formation by platelets that were exposed to arachidonic acid in a concentration-dependent manner but had no effect on the production of PGD(2), indicating an inhibitory effect on TXA(2) synthase. This was supported by a TXA(2) synthase activity assay that J78 concentration-dependently inhibited TXB(2) formation converted from PGH(2). Furthermore, J78 was also able to inhibit the [Ca(2+)](i) mobilization induced by collagen or thrombin at such a concentration that completely inhibited platelet aggregation. Taken together, these results suggest that the antiplatelet activity of J78 may be mediated by TXA(2) receptor blockade with TXA(2) synthase inhibition and suppression of cytosolic Ca(2+) mobilization.
Collapse
Affiliation(s)
- Yong-Ri Jin
- College of Pharmacy, Chungbuk National University, 48 Gaesin-Dong, Heungduk-Gu, Cheongju, Chungbuk, 361-763, Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
272
|
Kulkarni S, Jackson SP. Platelet Factor XIII and Calpain Negatively Regulate Integrin αIIbβ3 Adhesive Function and Thrombus Growth. J Biol Chem 2004; 279:30697-706. [PMID: 15131115 DOI: 10.1074/jbc.m403559200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Excessive accumulation of platelets at sites of athero-sclerotic plaque rupture leads to the development of arterial thrombi, precipitating clinical events such as the acute coronary syndromes and ischemic stroke. The major platelet adhesion receptor glycoprotein (GP) IIb-IIIa (integrin alpha(IIb)beta3) plays a central role in this process by promoting platelet aggregation and thrombus formation. We demonstrate here a novel mechanism down-regulating integrin alpha(IIb)beta3 adhesive function, involving platelet factor XIII (FXIII) and calpain, which serves to limit platelet aggregate formation and thrombus growth. This mechanism principally occurs in collagen-adherent platelets and is induced by prolonged elevations in cytosolic calcium, leading to dramatic changes in platelet morphology (membrane contraction, fragmentation, and microvesiculation) and a specific reduction in integrin alpha(IIb)beta3 adhesive function. Adhesion receptor signal transduction plays a major role in the process by sustaining cytosolic calcium flux necessary for calpain and FXIII activation. Analysis of thrombus formation on a type I fibrillar collagen substrate revealed an important role for FXIII and calpain in limiting platelet recruitment into developing aggregates, thereby leading to reduced thrombus formation. These studies define a previously unidentified role for platelet FXIII and calpain in regulating integrin alpha(IIb)beta3 adhesive function. Moreover, they demonstrate the existence of an autoregulatory feedback mechanism that serves to limit excessive platelet accumulation on highly reactive thrombogenic surfaces.
Collapse
Affiliation(s)
- Suhasini Kulkarni
- Australian Centre for Blood Diseases, Department of Medicine, Monash Medical School, Box Hill Hospital, Box Hill, Victoria 3128, Australia
| | | |
Collapse
|
273
|
Shattil SJ, Newman PJ. Integrins: dynamic scaffolds for adhesion and signaling in platelets. Blood 2004; 104:1606-15. [PMID: 15205259 DOI: 10.1182/blood-2004-04-1257] [Citation(s) in RCA: 406] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The major platelet integrin, alphaIIbbeta3, is required for platelet interactions with proteins in plasma and the extracellular matrices (ECMs) that are essential for platelet adhesion and aggregation during hemo stasis and arterial thrombosis. Lig and binding to alphaIIbbeta3 is controlled by inside-out signals that modulate receptor conformation and clustering. In turn, ligand binding triggers outside-in signals through alphaIIbbeta3 that, when disrupted, can cause a bleeding diathesis. In the past 5 years there has been an explosion of knowledge about the structure and function ofalphaIIbbeta3 and the related integrin, alphaVbeta3. These developments are discussed here, and current models of bidirectional alphaIIbbeta3 signaling are presented as frameworks for future investigations. An understanding that alphaIIbbeta3 functions as a dynamic molecular scaffold for extracellular and intracellular proteins has translated into diagnostic and therapeutic insights relevant to hematology and cardiovascular medicine, and further advances can be anticipated.
Collapse
Affiliation(s)
- Sanford J Shattil
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA, USA.
| | | |
Collapse
|
274
|
Boylan B, Chen H, Rathore V, Paddock C, Salacz M, Friedman KD, Curtis BR, Stapleton M, Newman DK, Kahn ML, Newman PJ. Anti-GPVI-associated ITP: an acquired platelet disorder caused by autoantibody-mediated clearance of the GPVI/FcRgamma-chain complex from the human platelet surface. Blood 2004; 104:1350-5. [PMID: 15150079 DOI: 10.1182/blood-2004-03-0896] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelet glycoprotein (GP) VI is a 62-kDa membrane glycoprotein that exists on both human and murine platelets in a noncovalent complex with the Fc receptor (FcR) gamma chain. The GPVI/FcRgamma-chain complex serves as the major activating receptor for collagen, as evidenced by observations that platelets genetically deficient in GPVI or the FcRgamma chain are highly refractory to collagen-induced platelet activation. Recently, several different rat anti-murine GPVI monoclonal antibodies, termed JAQs 1, 2, and 3, were produced that had the unique property of "immunodepleting" GPVI from the murine platelet surface and rendering it unresponsive to collagen or GPVI-specific agonists like convulxin or collagen-related peptide (CRP). Herein, we describe a patient with a mild bleeding disorder and a moderately reduced platelet count whose platelets fail to become activated in response to collagen or CRP and inefficiently adhere to and form thrombi on immobilized collagen under conditions of arterial shear. Although the amount of GPVI platelet mRNA and the nucleotide sequence of the GPVI gene were found to be normal, both GPVI and the FcRgamma chain were nearly absent from the platelet surface and were markedly reduced in wholeplatelet detergent lysates. Patient plasma contained an autoantibody that bound specifically to GPVI-positive, normal platelets, and cleared soluble GPVI from the plasma, suggesting that the patient suffers from a rare form of idiopathic thrombocytopenic purpura caused by a GPVI-specific autoantibody that mediates clearance of the GPVI/FcRgamma-chain complex from the platelet surface. Since antibody-induced GPVI shedding now has been demonstrated in both humans and mice, these studies may provide a rationale for developing therapeutic reagents that induce temporary depletion of GPVI for the treatment of clinical thrombosis.
Collapse
Affiliation(s)
- Brian Boylan
- Blood Research Institute, The Blood Center of Southeastern Wisconsin, PO Box 2178, 638 N 18th St, Milwaukee, WI 53201, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
275
|
Platelet GP Ib-IX-V: not just a binding protein. Blood 2004. [DOI: 10.1182/blood-2004-02-0668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
276
|
Dorsam RT, Kunapuli SP. Central role of the P2Y12 receptor in platelet activation. J Clin Invest 2004. [PMID: 14755328 DOI: 10.1172/jci200420986] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Platelet activation occurs in response to vessel injury and is important for the arrest of bleeding. Platelet activation during disease states leads to vascular occlusion and ischemic damage. The P2Y(12) receptor, activated by ADP, plays a central role in platelet activation and is the target of P2Y(12) receptor antagonists that have proven therapeutic value.
Collapse
Affiliation(s)
- Robert T Dorsam
- Department of Pharmacology, Temple University Medical School, Philadelphia, Pennsylvania 19140, USA
| | | |
Collapse
|
277
|
Abstract
Platelet activation occurs in response to vessel injury and is important for the arrest of bleeding. Platelet activation during disease states leads to vascular occlusion and ischemic damage. The P2Y(12) receptor, activated by ADP, plays a central role in platelet activation and is the target of P2Y(12) receptor antagonists that have proven therapeutic value.
Collapse
Affiliation(s)
- Robert T Dorsam
- Department of Pharmacology, Temple University Medical School, Philadelphia, Pennsylvania 19140, USA
| | | |
Collapse
|
278
|
Walther DJ, Peter JU, Winter S, Höltje M, Paulmann N, Grohmann M, Vowinckel J, Alamo-Bethencourt V, Wilhelm CS, Ahnert-Hilger G, Bader M. Serotonylation of small GTPases is a signal transduction pathway that triggers platelet alpha-granule release. Cell 2004; 115:851-62. [PMID: 14697203 DOI: 10.1016/s0092-8674(03)01014-6] [Citation(s) in RCA: 348] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Serotonin is a neurotransmitter in the central nervous system. In the periphery, serotonin functions as a ubiquitous hormone involved in vasoconstriction and platelet function. Serotonin is synthesized independently in peripheral tissues and neurons by two different rate-limiting tryptophan hydroxylase (TPH) isoenzymes. Here, we show that mice selectively deficient in peripheral TPH and serotonin exhibit impaired hemostasis, resulting in a reduced risk of thrombosis and thromboembolism, although the ultrastructure of the platelets is not affected. While the aggregation of serotonin-deficient platelets in vitro is apparently normal, their adhesion in vivo is reduced due to a blunted secretion of adhesive alpha-granular proteins. In elucidating the mechanism further, we demonstrate that serotonin is transamidated to small GTPases by transglutaminases during activation and aggregation of platelets, rendering these GTPases constitutively active. Our data provides evidence for a receptor-independent signaling mechanism, termed herein as "serotonylation," which leads to alpha-granule exocytosis from platelets.
Collapse
Affiliation(s)
- Diego J Walther
- Max-Planck-Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
279
|
Kasirer-Friede A, Cozzi MR, Mazzucato M, De Marco L, Ruggeri ZM, Shattil SJ. Signaling through GP Ib-IX-V activates alpha IIb beta 3 independently of other receptors. Blood 2004; 103:3403-11. [PMID: 14726383 DOI: 10.1182/blood-2003-10-3664] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Platelet adhesion to von Willebrand factor (VWF) activates alpha IIb beta 3, a prerequisite for thrombus formation. However, it is unclear whether the primary VWF receptor, glycoprotein (GP) Ib-IX-V, mediates alpha IIb beta 3 activation directly or through other signaling proteins physically associated with it (eg, FcR gamma-chain), possibly with the contribution of other agonist receptors and of VWF signaling through alpha IIb beta 3. To resolve this question, human and GP Ibalpha transgenic mouse platelets were plated on dimeric VWF A1 domain (dA1VWF), which engages only GP Ib-IX-V, in the presence of inhibitors of other agonist receptors. Platelet adhesion to dA1VWF induced Src kinase-dependent tyrosine phosphorylation of the FcR gamma-chain and the adapter molecule, ADAP, and triggered intracellular Ca(2+) oscillations and alpha IIb beta 3 activation. Inhibition of Ca(2+) oscillations with BAPTA-AM prevented alpha IIb beta 3 activation but not tyrosine phosphorylation. Pharmacologic inhibition of protein kinase C (PKC) or phosphatidylinositol 3-kinase (PI 3-kinase) prevented alpha IIb beta 3 activation but not Ca(2+) oscillations. Inhibition of Src with 2 distinct compounds blocked all responses downstream of GP Ib-IX-V under static or flow conditions. However, dA1VWF-induced responses were reduced only slightly in GP Ibalpha transgenic platelets lacking FcR gamma-chain. These data establish that GP Ib-IX-V itself can signal to activate alpha IIb beta 3, through sequential actions of Src kinases, Ca(2+) oscillations, and PI 3-kinase/PKC.
Collapse
Affiliation(s)
- Ana Kasirer-Friede
- Department of Cell Biology, The Scripps Research Institute, 10550 N Torrey Pines Rd, La Jolla, CA 92037, USA
| | | | | | | | | | | |
Collapse
|
280
|
Jagadeeswaran P, Cykowski M, Thattaliyath B. Vascular Occlusion and Thrombosis in Zebrafish. Methods Cell Biol 2004; 76:489-500. [PMID: 15602889 DOI: 10.1016/s0091-679x(04)76022-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Pudur Jagadeeswaran
- Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
| | | | | |
Collapse
|
281
|
Abstract
At the injured vessel wall, blood platelets become activated and adhere to the subendothelial surface as well as to each other. These cellular adhesion processes are required for primary hemostasis, but can also lead to thrombosis. Considerable progress has been made during recent years in understanding the molecular mechanisms underlying platelet activation and adhesion. This knowledge will drive future efforts towards the development of new antiplatelet drugs for the prevention and treatment of cardiovascular diseases.
Collapse
Affiliation(s)
- B Nieswandt
- Rudolf Virchow Center for Experimental Biomedicine, Vascular Biology, University of Würzburg, 97078, Würzburg, Germany
| | | |
Collapse
|
282
|
Marshall SJ, Senis YA, Auger JM, Feil R, Hofmann F, Salmon G, Peterson JT, Burslem F, Watson SP. GPIb-dependent platelet activation is dependent on Src kinases but not MAP kinase or cGMP-dependent kinase. Blood 2003; 103:2601-9. [PMID: 14684423 DOI: 10.1182/blood-2003-09-3319] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycoprotein Ib-IX-V (GPIb-IX-V) mediates platelet tethering to von Willebrand factor (VWF), recruiting platelets into the thrombus, and activates integrin alphaIIbbeta3 through a pathway that is dependent on Src kinases. In addition, recent reports indicate that activation of alphaIIbbeta3 by VWF is dependent on protein kinase G (PKG) and mitogen-activated protein (MAP) kinases. The present study compares the importance of these signaling pathways in the activation of alphaIIbbeta3 by GPIb-IX-V. In contrast to a recent report, VWF did not promote an increase in cyclic guanosine monophosphate (cGMP), while agents that elevate cGMP, such as the nitrous oxide (NO) donor glyco-SNAP-1 (N-(beta-D-glucopyranosyl)-N2-acetyl-S-nitroso-D,L-penicillaminamide) or the type 5 phosphosdiesterase inhibitor, sildenafil, inhibited rather than promoted activation of alphaIIbbeta3 by GPIb-IX-V and blocked aggregate formation on collagen at an intermediate rate of shear (800 s(-1)). Additionally, sildenafil increased blood flow in a rabbit model of thrombus formation in vivo. A novel inhibitor of the MAP kinase pathway, which is active in plasma, PD184161, had no effect on aggregate formation on collagen under flow conditions, whereas a novel inhibitor of Src kinases, which is also active in plasma, PD173952, blocked this response. These results demonstrate a critical role for Src kinases but not MAP kinases in VWF-dependent platelet activation and demonstrate an inhibitory role for cGMP-elevating agents in regulating this process.
Collapse
|
283
|
Jackson SP, Schoenwaelder SM. Antiplatelet therapy: in search of the 'magic bullet'. Nat Rev Drug Discov 2003; 2:775-89. [PMID: 14526381 DOI: 10.1038/nrd1198] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The central importance of platelets in the development of arterial thrombosis and cardiovascular disease is well established. No other single cell type is responsible for as much morbidity and mortality as the platelet and, as a consequence, it represents a major target for therapeutic intervention. The growing awareness of the importance of platelets is reflected in the increasing number of patients receiving antiplatelet therapy, a trend that is likely to continue in the future. There are, however, significant drawbacks with existing therapies, including issues related to limited efficacy and safety. The discovery of a 'magic bullet' that selectively targets pathological thrombus formation without undermining haemostasis remains elusive, although recent progress in unravelling the molecular events regulating thrombosis has provided promising new avenues to solve this long-standing problem.
Collapse
Affiliation(s)
- Shaun P Jackson
- The Australian Centre for Blood Diseases, Department of Medicine, Monash University, Arnold Street, Box Hill Hospital, Box Hill, Victoria 3128, Australia.
| | | |
Collapse
|