Department of Chemistry, University of Minnesota, Minneapolis, MN, USA.
Arterioscler Thromb Vasc Biol. 2013 Mar;33(3):481-8. doi: 10.1161/ATVBAHA.112.255737. Epub 2013 Jan 3.
Platelet granule exocytosis serves a central role in hemostasis and thrombosis. Recently, single-cell amperometry has shown that platelet membrane fusion during granule exocytosis results in the formation of a fusion pore that subsequently expands to enable the extrusion of granule contents. However, the molecular mechanisms that control platelet fusion pore expansion and collapse are not known.
We identified dynamin-related protein-1 (Drp1) in platelets and found that an inhibitor of Drp1, mdivi-1, blocked exocytosis of both platelet dense and α-granules. We used single-cell amperometry to monitor serotonin release from individual dense granules and, thereby, measured the effect of Drp1 inhibition on fusion pore dynamics. Inhibition of Drp1 increased spike width and decreased prespike foot events, indicating that Drp1 influences fusion pore formation and expansion. Platelet-mediated thrombus formation in vivo after laser-induced injury of mouse cremaster arterioles was impaired after infusion of mdivi-1.
These results demonstrate that inhibition of Drp1 disrupts platelet fusion pore dynamics and indicate that Drp1 can be targeted to control thrombus formation in vivo.
血小板颗粒胞吐作用在止血和血栓形成中起着核心作用。最近，单细胞安培法已经表明，血小板在颗粒胞吐过程中的膜融合导致融合孔的形成，随后融合孔扩张，从而允许颗粒内容物的挤出。然而，控制血小板融合孔扩张和塌陷的分子机制尚不清楚。
我们在血小板中鉴定出与 dynamin 相关蛋白-1（Drp1），并发现 Drp1 的抑制剂 mdivi-1 阻断了血小板致密颗粒和α颗粒的胞吐作用。我们使用单细胞安培法监测单个致密颗粒中 5-羟色胺的释放，从而测量 Drp1 抑制对融合孔动力学的影响。Drp1 的抑制增加了尖峰宽度，减少了尖峰前足事件，表明 Drp1 影响融合孔的形成和扩张。用激光诱导损伤小鼠肠系膜小动脉后，体内血小板介导的血栓形成在 mdivi-1 输注后受损。
这些结果表明，抑制 Drp1 破坏了血小板融合孔动力学，并表明可以靶向 Drp1 以控制体内血栓形成。
