Granule exocytosis is required for platelet spreading: differential sorting of α-granules expressing VAMP-7.
Granule exocytosis is required for platelet spreading: differential sorting of α-granules expressing VAMP-7.
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DOI：
10.1182/blood-2011-10-389247
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发表时间：
2012-07
期刊：
影响因子：
20.3
通讯作者：
Christian G Peters;A. Michelson;R. Flaumenhaft
中科院分区：
文献类型：
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作者：
Christian G Peters;A. Michelson;R. Flaumenhaft
最近关于血小板 α 颗粒是否代表单一颗粒群或由具有离散功能的不同亚群组成存在争议。为了解决这个问题，我们评估了囊泡相关膜蛋白（VAMP）在扩散血小板中的定位，以确定血小板在扩散过程中是否主动将特定的α颗粒亚群分类到外围。免疫荧光显微镜表明，表达 VAMP-3 和 VAMP-8 的颗粒与血管性血友病因子和血清素一起定位于扩散血小板的中央颗粒。相反，表达 VAMP-7 的 α 颗粒与颗粒货物 TIMP2 和 VEFG 一起易位到扩散血小板的外围。延时显微镜显示表达 VAMP-7 的 α 颗粒在扩散过程中主动从颗粒体移动到外围。灰血小板综合征患者的血小板缺乏 α 颗粒，并且仅表现出极小的扩散。同样，从 Unc13d(Jinx) 小鼠获得的血小板的扩散受到损害，这些小鼠缺乏 Munc13-4 并具有胞吐作用缺陷。这些研究鉴定了一种表达 VAMP-7 的新 α 颗粒亚型，该亚型在扩散过程中移动到外围，支持 α 颗粒是异质的前提，并证明血小板扩散需要颗粒胞吐作用。
There has been recent controversy as to whether platelet α-granules represent a single granule population or are composed of different subpopulations that serve discrete functions. To address this question, we evaluated the localization of vesicle-associated membrane proteins (VAMPs) in spread platelets to determine whether platelets actively sort a specific subpopulation of α-granules to the periphery during spreading. Immunofluorescence microscopy demonstrated that granules expressing VAMP-3 and VAMP-8 localized to the central granulomere of spread platelets along with the granule cargos von Willebrand factor and serotonin. In contrast, α-granules expressing VAMP-7 translocated to the periphery of spread platelets along with the granule cargos TIMP2 and VEFG. Time-lapse microscopy demonstrated that α-granules expressing VAMP-7 actively moved from the granulomere to the periphery during spreading. Platelets from a patient with gray platelet syndrome lacked α-granules and demonstrated only minimal spreading. Similarly, spreading was impaired in platelets obtained from Unc13d(Jinx) mice, which are deficient in Munc13-4 and have an exocytosis defect. These studies identify a new α-granule subtype expressing VAMP-7 that moves to the periphery during spreading, supporting the premise that α-granules are heterogeneous and demonstrating that granule exocytosis is required for platelet spreading.