Platelets synthesize large amounts of active plasminogen activator inhibitor 1.

Previous studies have suggested that plasminogen activator inhibitor 1 (PAI-1) released from platelets convey resistance of platelet-rich blood clots to thrombolysis. However, the majority of PAI-1 in platelets is inactive and therefore its role in clot stabilization is unclear. Because platelets retain mRNA and capacity for synthesis of some proteins, we investigated if platelets can de novo synthesize PAI-1 with an active configuration. PAI-1 mRNA was quantified with real-time polymerase chain reaction and considerable amounts of PAI-1 mRNA were detected in all platelet samples. Over 24 hours, the amount of PAI-1 protein as determined by an enzyme-linked immunosorbent assay increased by 25% (P = .001). Metabolic radiolabeling with (35)S-methionine followed by immunoprecipitation confirmed an ongoing PAI-1 synthesis, which could be further stimulated by thrombin and inhibited by puromycin. The activity of the newly formed PAI-1 was investigated by incubating platelets in the presence of tissue-type plasminogen activator (tPA). This functional assay showed that the majority of the new protein was in an active configuration and could complex-bind tPA. Thus, there is a continuous production of large amounts of active PAI-1 in platelets, which could be a mechanism by which platelets contribute to stabilization of blood clots.

[1]  R. Bohle,et al.  Characterization of platelet-specific mRNA by real-time PCR after laser-assisted microdissection , 2003, Thrombosis and Haemostasis.

[2]  P. Perrotta,et al.  Transcript profiling of human platelets using microarray and serial analysis of gene expression. , 2003, Blood.

[3]  H. Brogren,et al.  Quantification of ADP and ATP receptor expression in human platelets , 2003, Journal of thrombosis and haemostasis : JTH.

[4]  Koichi Sugimoto,et al.  Inhibition of Rho/Rho-kinase signaling downregulates plasminogen activator inhibitor-1 synthesis in cultured human monocytes. , 2002, Biochimica et biophysica acta.

[5]  C. Zeitz,et al.  Failed reperfusion after thrombolytic therapy: recognition and management. , 2002, Heart & lung : the journal of critical care.

[6]  G. Stone,et al.  Normal Flow (TIMI-3) Before Mechanical Reperfusion Therapy Is an Independent Determinant of Survival in Acute Myocardial Infarction: Analysis From the Primary Angioplasty in Myocardial Infarction Trials , 2001, Circulation.

[7]  D. Loskutoff,et al.  Plasminogen Activator Inhibitor-1 and Its Cofactor Vitronectin Stabilize Arterial Thrombi After Vascular Injury in Mice , 2001, Circulation.

[8]  D. Dixon,et al.  Signal-dependent translation of a regulatory protein, Bcl-3, in activated human platelets. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[9]  B. Wiman,et al.  Plasminogen activator inhibitor-1 (PAI-1) content in platelets from healthy individuals genotyped for the 4G/5G polymorphism in the PAI-1 gene. , 1997, Scandinavian journal of clinical and laboratory investigation.

[10]  I. Lang,et al.  Calcium-dependent Stabilization of Type I Plasminogen Activator Inhibitor within Plateletα-Granules (*) , 1996, The Journal of Biological Chemistry.

[11]  B. Bennett,et al.  Proteins of the Fibrinolytic System in Human Thrombi , 1996, Thrombosis and Haemostasis.

[12]  T. Kooistra,et al.  Studies on the acute release of tissue-type plasminogen activator from human endothelial cells in vitro and in rats in vivo: evidence for a dynamic storage pool. , 1995, Blood.

[13]  A. Hamsten,et al.  Allele-specific increase in basal transcription of the plasminogen-activator inhibitor 1 gene is associated with myocardial infarction. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[14]  I. Juhan-vague,et al.  Detection of Plasminogen Activator Inhibitor-1 (PAI-1) mRNA in Human Megakaryocytes by In Situ Hybridization , 1994, Thrombosis and Haemostasis.

[15]  V. Fuster,et al.  Lewis A. Conner Memorial Lecture. Mechanisms leading to myocardial infarction: insights from studies of vascular biology. , 1994, Circulation.

[16]  J. Sixma,et al.  Plasminogen activator inhibitor-1 released from activated platelets plays a key role in thrombolysis resistance. Studies with thrombi generated in the Chandler loop. , 1994, Arteriosclerosis and thrombosis : a journal of vascular biology.

[17]  D. Eitzman,et al.  Platelets inhibit fibrinolysis in vitro by both plasminogen activator inhibitor-1-dependent and -independent mechanisms. , 1994, Blood.

[18]  J. Hamilton,et al.  Macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor stimulate the synthesis of plasminogen-activator inhibitors by human monocytes. , 1993, Blood.

[19]  P. Tipping,et al.  Atheromatous plaque macrophages produce plasminogen activator inhibitor type-1 and stimulate its production by endothelial cells and vascular smooth muscle cells. , 1993, The American journal of pathology.

[20]  A. Henney,et al.  The two allele sequences of a common polymorphism in the promoter of the plasminogen activator inhibitor-1 (PAI-1) gene respond differently to interleukin-1 in HepG2 cells. , 1993, The Journal of biological chemistry.

[21]  B. Bennett,et al.  Lysis of Platelet‐rich Thrombi: The Role of PAI–1 a , 1992, Annals of the New York Academy of Sciences.

[22]  D. Rijken,et al.  The Amount of Plasminogen, Tissue-Type Plasminogen Activator and Plasminogen Activator Inhibitor Type 1 in Human Thrombi and the Relation to IVVO-TNO Lysibility , 1992, Thrombosis and Haemostasis.

[23]  B. Bennett,et al.  Distribution of plasminogen activator inhibitor (PAI-1) in tissues. , 1991, Journal of clinical pathology.

[24]  J. Mimuro.  [Type 1 plasminogen activator inhibitor]. , 1990, Rinsho byori. The Japanese journal of clinical pathology.

[25]  T. Lindahl,et al.  The mechanism of the reaction between human plasminogen-activator inhibitor 1 and tissue plasminogen activator. , 1990, The Biochemical journal.

[26]  B. Bennett,et al.  Plasminogen activator inhibitor (PAI‐1) in plasma and platelets , 1988, British journal of haematology.

[27]  J. Gorski,et al.  Enzymatic amplification of platelet-specific messenger RNA using the polymerase chain reaction. , 1988, The Journal of clinical investigation.

[28]  M. Alessi,et al.  Measurement of plasminogen activator inhibitor 1 in biologic fluids with a murine monoclonal antibody-based enzyme-linked immunosorbent assay. , 1988, Blood.

[29]  W. Vainchenker,et al.  Biosynthesis of major platelet proteins in human blood platelets. , 1987, European journal of biochemistry.

[30]  T. Kooistra,et al.  Rapid inactivation of the plasminogen-activator inhibitor upon secretion from cultured human endothelial cells. , 1986, The Biochemical journal.

[31]  D. Loskutoff,et al.  Immunoradiometric assay to measure the binding of a specific inhibitor to tissue-type plasminogen activator. , 1985, The Journal of laboratory and clinical medicine.

[32]  D. Loskutoff,et al.  Detection and partial characterization of an inhibitor of plasminogen activator in human platelets. , 1984, The Journal of clinical investigation.

[33]  M. Dewood,et al.  Coronary arteriographic findings in acute transmural myocardial infarction. , 1983, Circulation.

[34]  M S Golden,et al.  Prevalence of total coronary occlusion during the early hours of transmural myocardial infarction. , 1980, The New England journal of medicine.

[35]  F. Booyse,et al.  Stable messenger RNA in the synthesis of contractile protein in human platelets. , 1967, Biochimica et biophysica acta.

[36]  F. Booyse,et al.  In vitro Incorporation of Amino-acids into the Contractile Protein of Human Blood Platelets , 1967, Nature.

[37]  L. Laster,et al.  Protein synthesis by human platelets. , 1967, The Journal of biological chemistry.