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Platelet secretion requires Soluble N-ethylmaleimide Sensitive Attachment Protein Receptors (SNAREs). Vesicle SNAREs/Vesicle-Associated Membrane Proteins (v-SNAREs/VAMPs) on granules and t-SNAREs in plasma membranes mediate granule release. Platelet VAMP heterogeneity has complicated the assessment of how/if each is used and affects hemostasis. To address the importance of VAMP-7 (V7), we analyzed mice with global deletions of V3 and V7 together or platelet-specific deletions of V2, V3, and global deletion of V7. We measured the kinetics of cargo release, and its effects on three injury models to define the context-specific roles of these VAMPs. Loss of V7 minimally affected dense and a granule release but did affect lysosomal release. V3-/-7-/- and V2Δ3Δ7-/- platelets showed partial defects in a and lysosomal release; dense granule secretion was unaffected. In vivo assays showed that loss of V2, V3, and V7 caused no bleeding or occlusive thrombosis. These data indicate a role for V7 in lysosome release that is partially compensated by V3. V7 and V3, together, contribute to a granule release, however none of these deletions affected hemostasis/thrombosis. Our results confirm the dominance of V8. When it is present, deletion of V2, V3, or V7 alone or in combination minimally affects platelet secretion and hemostasis. [ABSTRACT FROM AUTHOR]

Platelets play many roles in the vasculature ensuring proper hemostasis and maintaining integrity. These roles are facilitated, in part, by cargo molecules released from platelet granules via Soluble NSF Attachment Protein Receptor (SNARE) mediated membrane fusion, which is controlled by several protein-protein interactions. Chaperones have been characterized for t-SNAREs (i.e. Munc18b for Syntaxin-11), but none have been clearly identified for v-SNAREs. a-Synuclein has been proposed as a v-SNARE chaperone which may affect SNARE-complex assembly, fusion pore opening, and thus secretion. Despite its abundance and that it is the only isoform present, a-synuclein's role in platelet secretion is uncharacterized. In this study, immunofluorescence showed that a-synuclein was present on punctate structures that costained with markers for a-granules and lysosomes and in a cytoplasmic pool. We analyzed the phenotype of a-synuclein-/- mice and their platelets. Platelets from knockout mice had a mild, agonist-dependent secretion defect but aggregation and spreading in vitro were unaffected. Consistently, thrombosis/hemostasis were unaffected in the tail-bleeding, FeCl3 carotid injury and jugular vein puncture models. None of the platelet secretory machinery examined, e.g. the v-SNAREs, were affected by a-synuclein's loss. The results indicate that, despite its abundance, a-synuclein has only a limited role in platelet function and thrombosis. [ABSTRACT FROM AUTHOR]

Platelet secretion requires Soluble N-ethylmaleimide Sensitive Attachment Protein Receptors (SNAREs). Vesicle SNAREs/Vesicle-Associated Membrane Proteins (v-SNAREs/VAMPs) on granules and t-SNAREs in plasma membranes mediate granule release. Platelet VAMP heterogeneity has complicated the assessment of how/if each is used and affects hemostasis. To address the importance of VAMP-7 (V7), we analyzed mice with global deletions of V3 and V7 together or platelet-specific deletions of V2, V3, and global deletion of V7. We measured the kinetics of cargo release, and its effects on three injury models to define the context-specific roles of these VAMPs. Loss of V7 minimally affected dense and α granule release but did affect lysosomal release. V3−/−7−/− and V2Δ3Δ7−/− platelets showed partial defects in α and lysosomal release; dense granule secretion was unaffected. In vivo assays showed that loss of V2, V3, and V7 caused no bleeding or occlusive thrombosis. These data indicate a role for V7 in lysosome release that is partially compensated by V3. V7 and V3, together, contribute to α granule release, however none of these deletions affected hemostasis/thrombosis. Our results confirm the dominance of V8. When it is present, deletion of V2, V3, or V7 alone or in combination minimally affects platelet secretion and hemostasis. What did we know? V8 is the primary VAMP isoform for platelet granule secretion, but V2 and V3 play compensatory roles. V3 is important for platelet endocytosis. V7 plays a minimal role in secretion and does not affect hemostasis. What did we discover? The loss of both V3 and V7 increases α and lysosomal secretion defects. Platelet-specific deletion of V2 and V3 with global V7-deletion causes defective α and lysosomal release. Secretion deficiencies in V3−/−7−/− and V2Δ3Δ7−/− have no effect on hemostasis or thrombosis. What is the impact? We show that endosomal v-SNAREs (V3 and V7) play minor roles in secretion. V3−/−7−/− and platelet-specific V2Δ3Δ7−/− mice are viable and will be valuable in in vivo studies of membrane trafficking. [ABSTRACT FROM AUTHOR]

Platelets play many roles in the vasculature ensuring proper hemostasis and maintaining integrity. These roles are facilitated, in part, by cargo molecules released from platelet granules via Soluble NSF Attachment Protein Receptor (SNARE) mediated membrane fusion, which is controlled by several protein-protein interactions. Chaperones have been characterized for t-SNAREs (i.e. Munc18b for Syntaxin-11), but none have been clearly identified for v-SNAREs. α-Synuclein has been proposed as a v-SNARE chaperone which may affect SNARE-complex assembly, fusion pore opening, and thus secretion. Despite its abundance and that it is the only isoform present, α-synuclein's role in platelet secretion is uncharacterized. In this study, immunofluorescence showed that α-synuclein was present on punctate structures that co-stained with markers for α-granules and lysosomes and in a cytoplasmic pool. We analyzed the phenotype of α-synuclein−/− mice and their platelets. Platelets from knockout mice had a mild, agonist-dependent secretion defect but aggregation and spreading in vitro were unaffected. Consistently, thrombosis/hemostasis were unaffected in the tail-bleeding, FeCl3 carotid injury and jugular vein puncture models. None of the platelet secretory machinery examined, e.g. the v-SNAREs, were affected by α-synuclein's loss. The results indicate that, despite its abundance, α-synuclein has only a limited role in platelet function and thrombosis. What did we know? The N-terminus of α-Synuclein affects SNARE-complex assembly, fusion pore opening, and granule docking. Microvascular bleeding is seen in Parkinson Disease patients where α-synuclein has a pathological role. What did we discover? α-Synuclein colocalizes with P-selectin (α-granules) and LAMP-1 (lysosomes) in platelets. The loss of α-synuclein has only a mild, agonist-dependent effect on platelet secretion. The loss of α-synuclein had no effect on thrombosis/hemostasis in 3 injury models. What is the impact? Despite its abundance, α-synuclein is not required for platelet secretion. α-Synuclein is not required for hemostasis or thrombosis. [ABSTRACT FROM AUTHOR]

Batch experiments were conducted to study the biosorption of Malachite Green (MG) onto polylactide (PLA)/spent brewery grains (SBGs) films. Films were prepared by solvent-casting method using dichloromethane. Effects of contact time, pH, salt concentration, and optimal experimental condition was evaluated. At pH 6.89 and low salt concentration, Malachite Green was removed effectively. The isotherm data fitted the Freundlich model with 0.969 R value and 0.738 slope implying chemisorptions process. The biosorption process followed pseudo-second order kinetics with calculated adsorption capacity at equilibrium (qe) of 0.572 mg/g at 23 °C. The investigation showed that PLA/SBGs films are effective in dye removal from textile, paper and leather industries effluents. [ABSTRACT FROM AUTHOR]