Activated, procoagulant platelets shed phosphatidylserine (PS)-exposing extracellular vesicles (EVs) from their surface in a Ca²⁺- and calpain-dependent manner. These PS-exposing EVs are prothrombotic and proinflammatory and are found at elevated levels in many cardiovascular and metabolic diseases. How PS-exposing EVs are shed is not fully understood. A clearer understanding of this process may aid the development of drugs to selectively block their release. In this study we report that 2-aminoethoxydiphenylborate (2-APB) significantly inhibits the release of PS-exposing EVs from platelets stimulated with the Ca²⁺ ionophore, A23187, or the pore-forming toxin, streptolysin-O. Two analogues of 2-APB, diphenylboronic anhydride (DPBA) and 3-(diphenylphosphino)-1-propylamine (DP3A), inhibited PS-exposing EV release with similar potency. Although 2-APB and DPBA weakly inhibited platelet PS exposure and calpain activity, this was not seen with DP3A despite inhibiting PS-exposing EV release. These data suggest that there is a further target of 2-APB, independent of cytosolic Ca²⁺ signalling, PS exposure and calpain activity, that is required for PS-exposing EV release. DP3A is likely to inhibit the same target, without these other effects. Identifying the target of 2-APB, DPBA and DP3A may provide a new way to inhibit PS-exposing EV release from activated platelets and inhibit their contribution to thrombosis and inflammation.

活化的促凝血血小板以 Ca ²⁺和钙蛋白酶依赖性方式从其表面脱落暴露于磷脂酰丝氨酸 (PS) 的细胞外囊泡 (EV)。这些暴露于 PS 的 EV 具有促血栓形成和促炎作用，并且在许多心血管和代谢疾病中的水平升高。暴露于 PS 的电动汽车如何脱落尚不完全清楚。更清楚地了解这一过程可能有助于开发选择性阻止其释放的药物。在这项研究中，我们报告说，2-氨基乙氧基二苯硼酸盐 (2-APB) 显着抑制经 Ca ²⁺离子载体 A23187 或成孔毒素链球菌溶血素-O 刺激的血小板中暴露 PS 的 EV 的释放。 2-APB 的两种类似物，二苯基硼酸酐 (DPBA) 和 3-(二苯基膦)-1-丙胺 (DP3A)，以相似的效力抑制暴露 PS 的 EV 释放。尽管 2-APB 和 DPBA 微弱地抑制血小板 PS 暴露和钙蛋白酶活性，但 DP3A 并未观察到这种情况，尽管抑制了暴露 PS 的 EV 释放。这些数据表明，2-APB 存在另一个目标，独立于胞质 Ca ²⁺信号传导、PS 暴露和钙蛋白酶活性，这是暴露 PS 的 EV 释放所必需的。 DP3A 可能会抑制相同的靶标，而没有这些其他作用。确定 2-APB、DPBA 和 DP3A 的靶点可能提供一种新方法来抑制活化血小板中暴露 PS 的 EV 释放，并抑制其对血栓形成和炎症的影响。