The cleaved peptide of the thrombin receptor is a strong platelet agonist
Authors
Furman, Mark I.Liu, Longbin
Benoit, Stephen E.
Becker, Richard C.
Barnard, Marc R.
Michelson, Alan D.
Document Type
Journal ArticlePublication Date
1998-04-18Keywords
Amino Acid SequenceAndrostadienes
Blood Platelets
Dose-Response Relationship, Drug
Drug Synergism
Enzyme Inhibitors
Genistein
Humans
Molecular Sequence Data
Peptide Fragments
Platelet Activation
Platelet Glycoprotein GPIIb-IIIa Complex
Platelet Glycoprotein GPIb-IX Complex
Signal Transduction
Staurosporine
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
Thrombin cleaves its G-protein-linked seven-transmembrane domain receptor, thereby releasing a 41-aa peptide and generating a new amino terminus that acts as a tethered ligand for the receptor. Peptides corresponding to the new amino terminal end of the proteolyzed seven-transmembrane domain thrombin receptor [TR42-55, SFLLRNPNDKYEPF, also known as TRAP (thrombin receptor-activating peptide)], previously have been demonstrated to activate the receptor. In this study, we demonstrate that the 41-aa cleaved peptide, TR1-41 (MGPRRLLLVAACFSLCGPLLSARTRARRPESKATNATLDPR) is a strong platelet agonist. TR1-41 induces platelet aggregation. In whole-blood flow cytometric studies, TR1-41 was shown to be more potent than TR42-55 and almost as potent as thrombin, as determined by the degree of increase in: (i) platelet surface expression of P-selectin (reflecting alpha granule secretion); (ii) exposure of the fibrinogen binding site on the glycoprotein (GP) IIb-IIIa complex; and (iii) fibrinogen binding to the activated GPIIb-IIIa complex. As determined by experiments with inhibitors [prostaglandin I2, staurosporine, wortmannin, the endothelium-derived relaxing factor congener S-nitroso-N-acetylcysteine (SNAC), EDTA, EGTA, and genestein], and with Bernard-Soulier or Glanzmann's platelets, we demonstrated that TR1-41-induced platelet activation is: (i) inhibited by cyclic AMP; (ii) mediated by protein kinase C, phosphatidyl inositol-3-kinase, myosin light chain kinase, and intracellular protein tyrosine kinases; (iii) dependent on extracellular calcium; and (iv) independent of the GPIb-IX and GPIIb-IIIa complexes. TR1-41-induced platelet activation was synergistic with TR42-55. In summary, the cleaved peptide of the seven-transmembrane domain TR (TR1-41) is a strong platelet agonist.Source
Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3082-7.
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http://hdl.handle.net/20.500.14038/38962PubMed ID
9501219Related Resources
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In vitro testing of fresh and lyophilized reconstituted human and baboon plateletsValeri, C. Robert; Macgregor, Hollace; Barnard, Marc R.; Summaria, L.; Michelson, Alan D.; Ragno, G. (2004-10-01)BACKGROUND: Studies have been performed on human fresh, liquid-preserved, and cryopreserved platelets (PLTs) to assess PLT-adhesive surface receptors, PLT membrane procoagulant activity, PLT aggregation, and thromboxane production. Lyophilization has been developed as a method to preserve PLTs. This study was performed to evaluate these measurements on human and baboon fresh and lyophilized reconstituted PLTs. STUDY DESIGN AND METHODS: In both human and baboon fresh and lyophilized PLTs, aggregation response and PLT production of thromboxane A2 were measured after stimulation, and PLT surface markers P-selectin, glycoprotein (GP) Ib, GPIIb-IIIa, and factor (F) V were measured before and after stimulation. RESULTS: Fresh PLTs responded to the dual agonists arachidonic acid and adenosine diphosphate (ADP) to aggregate and produce thromboxane A2, and in both the PLT surface markers P-selectin and GPIIb-IIIa increased and GPIb decreased after stimulation. Neither human nor baboon lyophilized reconstituted PLTs aggregated to dual agonists, and neither produced thromboxane A2, increased PLT surface markers P-selectin or GPIIb-IIIa, or decreased PLT GPIb after stimulation. Nevertheless, after recalcification the lyophilized reconstituted PLTs accumulated FV to a significantly greater degree than fresh PLTs. CONCLUSIONS: Lyophilized reconstituted PLTs exhibited modification of the PLT membrane that interfered with aggregation and thromboxane production, prevented increases in PLT P-selectin and GPIIb-IIIa and decreases in GPIb after stimulation, and increased FV accumulation after recalcification. The in vitro data suggest that lyophilized PLTs may have reduced in vivo survival. In vivo studies are needed to determine the survival and function of lyophilized PLTs.