Wei Hao, Davies Jessica E, Harper Matthew T
Department of Pharmacology, University of Cambridge, Cambridge, UK.
Cell Death Discov. 2020 Mar 2;6:10. doi: 10.1038/s41420-020-0244-9. eCollection 2020.
Activated, procoagulant platelets shed phosphatidylserine (PS)-exposing extracellular vesicles (EVs) from their surface in a Ca- 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 Ca 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 Ca 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钙和钙蛋白酶依赖性方式从其表面释放暴露磷脂酰丝氨酸（PS）的细胞外囊泡（EVs）。这些暴露PS的EVs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水平升高。暴露PS的EVs如何释放尚不完全清楚。更清楚地了解这一过程可能有助于开发选择性阻断其释放的药物。在本研究中，我们报告2-氨基乙氧基二苯硼酸盐（2-APB）显著抑制用钙离子载体A23187或成孔毒素链球菌溶血素-O刺激的血小板释放暴露PS的EVs。2-APB的两种类似物，二苯硼酸酐（DPBA）和3-（二苯基膦基）-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，但尽管DP3A抑制暴露PS的EV释放，但未观察到这种情况。这些数据表明，存在2-APB的另一个靶点，其独立于胞质钙信号传导、PS暴露和钙蛋白酶活性，是暴露PS的EV释放所必需的。DP3A可能抑制相同的靶点，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释放暴露PS的EV，并抑制它们对血栓形成和炎症的作用。
