In:
Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 34, No. suppl_1 ( 2014-05)
Abstract:
Introduction: PDI and ERp57 are members of the thiol isomerase family of enzymes that are released to the platelet surface where they contribute to a range of platelet responses. PDI has been reported to be present in subcellular structures in resting platelets, although it is excluded from α - and δ -granules, and lysosomes. It was, however, recently shown to co-localise with TLR9 in T-granules, intracellular bodies underlying the plasma membrane. The subcellular localisation of other platelet thiol isomerases or their mechanisms of translocation to the cell surface have not been established. Hypothesis and Methods: Using spinning disk confocal microscopy we sought to explore whether platelet thiol isomerases ERp57 and PDI are co-localised in resting and activated platelets and to test the hypothesis that translocation of thiol isomerases to the platelet surface is dependent on actin polymerization. Results and Conclusions: In resting platelets, PDI and ERp57 were organized in punctate structures both on the platelet surface and in the cytoplasm. They did not colocalise with P-selectin consistent with them residing outside α -granules. In contrast to expectations, TLR9 did not colocalize with PDI and ERp57, suggesting their exclusion from T-granules. Partial colocalization was observed in resting platelets between PDI and ERp57 in granule-like structures. Upon platelet activation, this degree of co-distribution persisted with PDI and ERp57 migrating to the platelet surface. Latrunculin A, an inhibitor of actin polymerization, decreased P-selectin exposure on the platelet surface, as measured by flow cytometry, and agonist-stimulated platelets treated with this agent retained a rounded shape, as shown by tubulin staining. Importantly, latrunculin A also blocked the translocation of PDI and ERp57 from internal granule-like structures to the platelet surface. We conclude that in resting platelets PDI and ERp57 are organized, and partially co-localised, in punctuate structures unlikely to represent α- or T-granules. The polymerization of actin during platelet activation exerts a fundamental role in the relocalization of PDI and ERp57 from these cytoplasmic structures to the platelet surface.
Type of Medium:
Online Resource
ISSN:
1079-5642
,
1524-4636
DOI:
10.1161/atvb.34.suppl_1.380
Language:
English
Publisher:
Ovid Technologies (Wolters Kluwer Health)
Publication Date:
2014
detail.hit.zdb_id:
1494427-3
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