Papers by Ewelina Golebiewska
The Journal of Biological Chemistry, Nov 17, 2014
Platelet secretion not only drives thrombosis and hemostasis, but also mediates a variety of othe... more Platelet secretion not only drives thrombosis and hemostasis, but also mediates a variety of other physiological and pathological processes. The ubiquitous SNARE machinery and a number of accessory proteins have been implicated in regulating secretion in platelets. Although several platelets SNAREs have been identified, further members of the SNARE family may be needed to fine-tune platelet secretion. In this study we identified expression of the t-SNARE syntaxin 8 (STX8) (Qc SNARE) in mouse and human platelets. In mouse studies, whereas STX8 was not essential for α-granule or lysosome secretion, Stx8-/- platelets showed a significant defect in dense granule secretion in response to thrombin and CRP. This was most pronounced at intermediate concentrations of agonists. They also showed an aggregation defect that could be rescued with exogenous ADP and increased embolization in Stx8-/- mice in vivo consistent with an important autocrine and paracrine role for ADP in aggregation and thrombus stabilization. STX8 therefore specifically contributes to dense granule secretion and represents another member of a growing family of genes that play distinct roles in regulating granule release from platelets and thus platelet function in thrombosis and hemostasis.
Blood Reviews, Oct 31, 2014
Upon activation, platelets secrete more than 300 active substances from their intracellular granu... more Upon activation, platelets secrete more than 300 active substances from their intracellular granules. Platelet dense granule components, such as ADP and polyphosphates, contribute to haemostasis and coagulation, but also play a role in cancer metastasis. α-Granules contain multiple cytokines, mitogens, pro- and anti-inflammatory factors and other bioactive molecules that are essential regulators in the complex microenvironment of the growing thrombus but also contribute to a number of disease processes. Our understanding of the molecular mechanisms of secretion and the genetic regulation of granule biogenesis still remains incomplete. In this review we summarise our current understanding of the roles of platelet secretion in health and disease, and discuss some of the hypotheses that may explain how platelets may control the release of its many secreted components in a context-specific manner, to allow platelets to play multiple roles in health and disease.
Blood Reviews, Nov 30, 2013
Upon activation by extracellular matrix components or soluble agonists, platelets release in exce... more Upon activation by extracellular matrix components or soluble agonists, platelets release in excess of 300 active molecules from intracellular granules. Those factors can both activate further platelets and mediate a range of responses in other cells. The complex microenvironment of a growing thrombus, as well as platelets' roles in both physiological and pathological processes, require platelet secretion to be highly spatially and temporally regulated to ensure appropriate responses to a range of stimuli. However, how this regulation is achieved remains incompletely understood. In this review we outline the importance of regulated secretion in thrombosis as well as in ‘novel’ scenarios beyond haemostasis and give a detailed summary of what is known about the molecular mechanisms of platelet exocytosis. We also discuss a number of theories of how different cargoes could be released in a tightly orchestrated manner, allowing complex interactions between platelets and their environment.
Thesis by Ewelina Golebiewska
University of Bristol Theses, May 25, 2014
Platelet secretion not only drives thrombosis and haemostasis, but also mediates a variety of oth... more Platelet secretion not only drives thrombosis and haemostasis, but also mediates a variety of other physiological and pathological processes. The ubiquitous SNARE machinery and a number of accessory proteins have been implicated in regulating secretion in platelets. Although several platelet SNAREs have been identified, further members of the SNARE family may help fine-tune platelet secretion. In this study I identified expression of t-SNAREs VTI1A, VTI1B (Qb SNAREs) and STX8 (Qc SNARE) in human and mouse platelets. Those ‘novel’ SNAREs were able to interact with each other and previously reported SNAREs VAMP8 (R-SNARE) and STX11 (Qa SNARE), thus suggesting existence of a secondary SNARE complex in addition to the widely accepted SNAP23-VAMP8-STX11 complex. In following mouse studies, whereas neither gene was found to
be essential for α-granule or lysosome secretion, Stx8-/- platelets showed a significant defect in dense granule secretion and aggregation, that was most pronounced at intermediate concentrations of agonists. Addition of exogenous ADP could rescue the aggregation defect but failed to restore dense granule secretion, suggesting the defect lies in the ‘primary’ secretory pathway. Pretreatment with P2Y receptors antagonists reduced secretion and aggregation to the same extent in WT and Stx8-/- platelets, suggesting that the ADP-driven positive feedback mechanism was not defective in Stx8-/- platelets. In addition, STX8 was found to play a role in regulating pro-coagulant activity suggesting novel roles for SNAREs in platelets. Neither Vti1a-/- nor Vti1b-/- showed any
significant defects, suggesting complementarity between those homologues in
platelets. STX8 therefore specifically contributes to dense granule secretion and
represents another member of a growing family of genes that play distinct roles
in differentially regulating granule release from platelets. Taken together, data
presented in this Thesis not only provides first evidence of an additional SNARE complex present in platelets but also suggests novel roles for SNAREs in regulation of thrombosis and haemostasis
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Papers by Ewelina Golebiewska
Thesis by Ewelina Golebiewska
be essential for α-granule or lysosome secretion, Stx8-/- platelets showed a significant defect in dense granule secretion and aggregation, that was most pronounced at intermediate concentrations of agonists. Addition of exogenous ADP could rescue the aggregation defect but failed to restore dense granule secretion, suggesting the defect lies in the ‘primary’ secretory pathway. Pretreatment with P2Y receptors antagonists reduced secretion and aggregation to the same extent in WT and Stx8-/- platelets, suggesting that the ADP-driven positive feedback mechanism was not defective in Stx8-/- platelets. In addition, STX8 was found to play a role in regulating pro-coagulant activity suggesting novel roles for SNAREs in platelets. Neither Vti1a-/- nor Vti1b-/- showed any
significant defects, suggesting complementarity between those homologues in
platelets. STX8 therefore specifically contributes to dense granule secretion and
represents another member of a growing family of genes that play distinct roles
in differentially regulating granule release from platelets. Taken together, data
presented in this Thesis not only provides first evidence of an additional SNARE complex present in platelets but also suggests novel roles for SNAREs in regulation of thrombosis and haemostasis
be essential for α-granule or lysosome secretion, Stx8-/- platelets showed a significant defect in dense granule secretion and aggregation, that was most pronounced at intermediate concentrations of agonists. Addition of exogenous ADP could rescue the aggregation defect but failed to restore dense granule secretion, suggesting the defect lies in the ‘primary’ secretory pathway. Pretreatment with P2Y receptors antagonists reduced secretion and aggregation to the same extent in WT and Stx8-/- platelets, suggesting that the ADP-driven positive feedback mechanism was not defective in Stx8-/- platelets. In addition, STX8 was found to play a role in regulating pro-coagulant activity suggesting novel roles for SNAREs in platelets. Neither Vti1a-/- nor Vti1b-/- showed any
significant defects, suggesting complementarity between those homologues in
platelets. STX8 therefore specifically contributes to dense granule secretion and
represents another member of a growing family of genes that play distinct roles
in differentially regulating granule release from platelets. Taken together, data
presented in this Thesis not only provides first evidence of an additional SNARE complex present in platelets but also suggests novel roles for SNAREs in regulation of thrombosis and haemostasis