Calpain-controlled detachment of major glycoproteins from cytoskeleton regulates adhesive properties of phosphatidylserine-positive activated plateletsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 20 апреля 2016 г.
Аннотация:In resting platelets, adhesive membrane glycoproteins are attached to the cytoskeleton. Upon strong activation, phosphatidylserine(PS)-positive and PS-negative platelet subpopulations are formed. Platelet activation is accompanied by cytoskeletal rearrangement, but glycoprotein attachment status in these two subpopulations is not clear. We developed a new flow cytometry-based single-cell approach to investigate attachment of membrane glycoproteins to cytoskeleton in cell subpopulations. In PS-negative platelets, adhesive glycoproteins integrin αIIbβ3, glycoprotein Ib and, as shown for the first time, P-selectin were associated with cytoskeleton. In contrast, this attachment was disrupted in PS-positive platelets; it was retained to some extent only in the small convex regions, "caps". It correlated with degradation of talin and filamin observed in PS-positive platelets only. Calpain inhibitors essentially prevented the disruption of membrane glycoprotein attachment in PS-positive platelets, as well as talin and filamin degradation. Suggesting that detachment of glycoproteins from cytoskeleton may affect platelet adhesive properties, we investigated the ability of PS-positive platelets to resist shear-induced breakaway from the immobilized fibrinogen. Shear rates of 500 s(-1) caused PS-positive platelet breakaway, but their adhesion stability increased more than 10-fold after the pretreatment of platelets with calpain inhibitor. In contrast, the ability of PS-positive platelets to adhere to immobilized von Willebrand factor at 100 s(-1) was low but this was not affected by preincubation of platelets with calpain inhibitor. Our data suggest that calpain-controlled detachment of membrane glycoproteins is a new mechanism responsible for the loss of procoagulant platelet ability to resist detachment from thrombi by high shear.