Studies on human platelets. I. Synthesis of platelet protein in a cell-free system

Booyse, François M.; Rafelson, Max E.

doi:10.1016/0005-2787(68)90376-6

Cited by 61 publications

(46 citation statements)

References 11 publications

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“…Although platelets are anucleate and lack nuclear DNA, they retain megakaryocyte-derived mRNA (5) and retain the ability for protein synthesis from cytoplasmic mRNA (6,30). The purity of fetal platelets isolated and lack of contamination by leucocytes, demonstrated by flow cytometry, was also confirmed by measurement of RNA recovery which was 1,000 times lower than that extracted from a similar volume of T lymphocytes (data not shown).…”

Section: Discussionmentioning

confidence: 87%

Taurine transporter in fetal T lymphocytes and platelets: differential expression and functional activity

Iruloh

D'Souza²,

Speake³

et al. 2007

American Journal of Physiology-Cell Physiology

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Transplacental transfer of taurine, a ␤-amino acid essential for fetal and neonatal development, constitutes the primary source of taurine for the fetus. Placental transport of taurine is compromised in pregnancies complicated by intrauterine growth restriction, resulting in a reduced concentration of taurine in cord plasma. This could impact on fetal cellular metabolism as taurine represents the most abundant intracellular amino acid in many fetal cell types. In the present study, we have used pure isolates of fetal platelets and T lymphocytes from cord blood of placentas, from normal, term pregnancies, as fetal cell types to examine the cellular uptake mechanisms for taurine by the system ␤ transporter and have compared gene and protein expression for the taurine transporter protein (TAUT) in these two cell types. System ␤ activity in fetal platelets was 15-fold higher compared with fetal T lymphocytes (P Ͻ 0.005), mirroring greater TAUT mRNA expression in platelets than T lymphocytes (P Ͻ 0.005). Cell-specific differences in TAUT protein moieties were detected with a doublet of 75 and 80 kDa in fetal platelets compared with 114 and 120 kDa in fetal T lymphocytes, with relatively higher expression in platelets. We conclude that greater system ␤ activity in fetal platelets compared with T lymphocytes is the result of relatively greater TAUT mRNA and protein expression. This study represents the first characterization of amino acid transporters in fetal T lymphocytes. cord blood cells; amino acid; taurine transporter protein; system ␤ TAURINE (2-aminoethanesulfonic acid) is the most abundant free amino acid in several tissues, including the placenta and the cellular components of blood (9,21,38,41,46). It is a ␤-amino acid with the sulfonic acid group attached to the ␤-carbon atom and is not incorporated into proteins (14). The physiological functions of taurine are diverse, including bile and xenobiotic conjugation, regulation of neuronal excitability, membrane protection, antioxidation, detoxification, and osmoregulation (22,24,31). The nutritional requirements for taurine are met both by dietary sources and biosynthesis from cysteine and methionine (53). However, in the human fetus and the neonate, taurine is an essential amino acid, as biosynthetic capacity is almost negligible (51) due to the lack of cysteine sulfonic acid decarboxylase, which catalyses the rate-limiting step in taurine synthesis (4). Transplacental transfer of taurine from maternal blood therefore constitutes the primary source of fetal taurine.Taurine is transported across cell membranes, including those of the syncytiotrophoblast, the transporting epithelium of human placenta, by the system ␤-amino acid transport system which is specific for taurine and other ␤-amino acids such as ␤-alanine and hypotaurine (29,32,36). System ␤ is a highaffinity, low-capacity transport system that is Na ϩ -and Cl Ϫ -dependent (10) with a 2:1:1 Na ϩ :Cl Ϫ :taurine stoichiometry (39, 48). System ␤ activity has been demonstrated in many cell types and its ca...

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Section: Discussionmentioning

confidence: 87%

Taurine transporter in fetal T lymphocytes and platelets: differential expression and functional activity

Iruloh

D'Souza²,

Speake³

et al. 2007

American Journal of Physiology-Cell Physiology

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“…Using a cell-free system consisting of fractions from homogenates of resting human platelets, Booyse and Rafelson showed that platelet ribosomes are functional and that the lysate system mediated incorporation of radiolabeled amino acids into newly synthesized proteins. 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.…”

Section: Mature Human Platelets Have Essential Components Required Fomentioning

confidence: 92%

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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“…However, platelets retain a small but functionally significant amount of megakaryocyte-derived RNA as well as the proteins and molecular machinery necessary for translation. Furthermore, platelets can respond to physiological stimuli using biosynthetic processes that are regulated at the level of protein translation (8,9), demonstrating a functional role for platelet mRNA (10,11).…”

Section: Genomics Without a Genome: The Platelet Transcriptomementioning

confidence: 99%

Platelet genomics and proteomics in human health and disease

Macaulay

Carr²,

Gusnanto³

et al. 2005

Journal of Clinical Investigation

150

100

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Proteomic and genomic technologies provide powerful tools for characterizing the multitude of events that occur in the anucleate platelet. These technologies are beginning to define the complete platelet transcriptome and proteome as well as the protein-protein interactions critical for platelet function. The integration of these results provides the opportunity to identify those proteins involved in discrete facets of platelet function. Here we summarize the findings of platelet proteome and transcriptome studies and their application to diseases of platelet function.

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Studies on human platelets. I. Synthesis of platelet protein in a cell-free system

Cited by 61 publications

References 11 publications

Taurine transporter in fetal T lymphocytes and platelets: differential expression and functional activity

Taurine transporter in fetal T lymphocytes and platelets: differential expression and functional activity

Signal-Dependent Protein Synthesis by Activated Platelets

Platelet genomics and proteomics in human health and disease

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