In vitro Incorporation of Amino-acids into the Contractile Protein of Human Blood Platelets

Booyse, François M.; Rafelson, Max E.

doi:10.1038/215283a0

Cited by 60 publications

(33 citation statements)

References 11 publications

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“…Chambers, Salzman, Neri, and Sivertsen (41) similarly were unable to demonstrate incorporation of radioactive amino acids into platelets suspended in platelet-rich plasma. In vitro incorporation of some labeled amino acids into washed platelets has been demonstrated (42,43). The differences in experimental design may account for the apparent discrepancy, or perhaps a quantitative difference exists between transport mechanisms for different amino acids.…”

Section: Resultsmentioning

confidence: 99%

Measurement of thrombopoiesis in rabbits using 75selenomethionine

Evatt¹,

Levin²

1969

J. Clin. Invest.

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A B S T R A C T Incorporation of 'selenomethionine ('SeM) has been used to study platelet production in rabbits. Radioactivity of platelets was low after the intravenous administration of 'SeM and rose to a maximum approximately 3 days after administration. Platelet radioactivity was independent of concurrent plasma levels. The life span of rabbit platelets, as estimated with this technique, was 4-5 days. In vivo reutilization of '7SeM previously incorporated into plasma proteins was not detected. In vitro incorporation of 'SeM by platelets in platelet-rich plasma was not demonstrated.Acute hemorrhage 24 hr before administration of 'SeM increased the incorporation of 'SeM into platelets. Transfusion-induced thrombocytosis reduced the incorporation of 'SeM to approximately 30% of that observed in control animals. Suppression of bone marrow function with nitrogen mustard resulted in decreased numbers of platelets in the circulation, and a decrease in incorporation of 'SeM. Delayed appearance of '7SeM was observed in circulating platelets during recovery from marrow suppression. Injection of 75-225 ml of plasma from thrombocytopenic donors into normal rabbits increased incorporation of 'SeM into platelets while normal plasma did not have this effect.The rate of appearance of 'SeM in circulating platelets appears to provide a sensitive and specific method for the study of production of platelets by megakaryocytes. The data suggest more rapid entry of platelets into the circulation, and a sustained increase in incorporation of 'SeM into platelet protein after stimulation of platelet production. The results are consistent with the concept of a humoral agent (thrombopoietin) that acts on megakaryocytes to regulate platelet production.

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Section: Resultsmentioning

confidence: 99%

Measurement of thrombopoiesis in rabbits using 75selenomethionine

Evatt¹,

Levin²

1969

J. Clin. Invest.

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“…30 Puromycin, an inhibitor of translation-but not actinomycin D, an inhibitor of transcriptionblocked new protein synthesis by isolated human platelets in these studies. 25,27,31 This is a classic pattern indicative of posttranscriptional control. Essentially, all of the platelets isolated from normal subjects incorporated radiolabeled amino acids into new protein, 28 demonstrating that this function is not a property of a subset of immature cells.…”

Section: Mature Human Platelets Have Essential Components Required Fomentioning

confidence: 99%

“…18 In parallel, these investigators and others reported that intact washed human platelets incorporate labeled amino acids into protein products. [25][26][27][28][29] Rat platelets also incorporate exogenous amino acids into new protein. 30 Puromycin, an inhibitor of translation-but not actinomycin D, an inhibitor of transcriptionblocked new protein synthesis by isolated human platelets in these studies.…”

Section: Mature Human Platelets Have Essential Components Required Fomentioning

confidence: 99%

Signal-Dependent Protein Synthesis by Activated Platelets

Zimmerman

Weyrich

2008

ATVB

180

146

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Abstract-New biologic activities of platelets continue to be discovered, indicating that concepts of platelet function in hemostasis, thrombosis, and inflammation require reconsideration as new paradigms evolve. Studies done over 3 decades ago demonstrated that mature circulating platelets have protein synthetic capacity, but it was thought to be low level and inconsequential. In contrast, recent discoveries demonstrate that platelets synthesize protein products with important biologic activities in a rapid and sustained fashion in response to cellular activation. This process, termed signal-dependent translation, uses a constitutive transcriptome and specialized pathways, and can alter platelet phenotype and functions in a fashion that can have clinical relevance.

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“…The population of circulating platelets is not homogeneous [33], immature platelets comprise the youngest component of the circulating platelet pool, and appear to participate most actively in the thrombotic process [34]. They contain measurable amounts of cytosolic messenger ribonucleic acid (mRNA) that is translationally active [35]. There is concordance between the level of circulating young platelets and the proportion of subjects who are hyporesponsive to aspirin or clopidogrel, indicating that the presence of young platelets may attenuate the inhibitory effects of these agents [28,33,36] (the "platelet quality hypothesis").…”

Section: The "Fiction Of the Perpetually Platelet Inactivation"mentioning

confidence: 99%

“…Although this mRNA was at one time considered inconsequential, a growing body of evidence indicates the presence of spliceosome complexes in these platelets and that activation-dependent splicing and translation of pre-mRNA results in the de novo synthesis of prothrombotic and proinflammatory proteins [28,35]. Ibrahim et al demonstrated that the number of immature platelets could be considered a biomarker for MACE risk stratification in patients with coronary artery disease [37,38].…”

Section: The "Fiction Of the Perpetually Platelet Inactivation"mentioning

confidence: 99%