Megakaryocytes package contents into separate α-granules that are differentially distributed in platelets
Megakaryocytes package contents into separate α-granules that are differentially distributed in platelets
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DOI：
10.1182/bloodadvances.2018020834
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发表时间：
2019-10-22
期刊：
影响因子：
7.5
通讯作者：
Italiano, Joseph E., Jr.
中科院分区：
文献类型：
--
作者：
Battinelli, Elisabeth M.;Thon, Jonathan N.;Italiano, Joseph E., Jr.
除了它们在止血和血栓形成中的主要作用之外，血小板还参与许多其他生理和病理过程，包括但不限于炎症、伤口愈合、肿瘤转移和血管生成。它们最有趣的特性之一是大量的生物活性蛋白质储存在它们的α颗粒中，α颗粒是血小板的主要储存颗粒。我们以前表明，血小板差异包装亲和抗血管生成蛋白在不同的α-颗粒，血小板活化后进行差异释放。然而，巨核细胞如何实现差异包装还没有完全了解。在这项研究中，我们使用小鼠巨核细胞培养系统和内吞试验，以建立在血小板生产过程中何时何地发生差异包装。原代小鼠巨核细胞与荧光结合的纤维蛋白原和内皮抑制素孵育的活细胞显微镜显示不同的内吞和包装的标记蛋白质成不同的α-颗粒亚群。小鼠前血小板和人全血血小板α颗粒的超分辨率显微镜同时探测2种不同的膜蛋白（VAMP-3和VAMP-8）和多种颗粒内容物蛋白（bFGF、ENDO、TSP、VEGF），证实了蛋白内容物差异包装成α颗粒。这些数据表明，巨核细胞差异排序和包装α-颗粒内容物，这是保存在前血小板的延伸和血小板生产的α-颗粒亚群。
In addition to their primary roles in hemostasis and thrombosis, platelets participate in many other physiological and pathological processes, including, but not limited to inflammation, wound healing, tumor metastasis, and angiogenesis. Among their most interesting properties is the large number of bioactive proteins stored in their alpha-granules, the major storage granule of platelets. We previously showed that platelets differentially package pro- and antiangiogenic proteins in distinct alpha-granules that undergo differential release upon platelet activation. Nevertheless, how megakaryocytes achieve differential packaging is not fully understood. In this study, we use a mouse megakaryocyte culture system and endocytosis assay to establish when and where differential packaging occurs during platelet production. Live cell microscopy of primary mouse megakaryocytes incubated with fluorescently conjugated fibrinogen and endostatin showed differential endocytosis and packaging of the labeled proteins into distinct alpha-granule subpopulations. Super-resolution microscopy of mouse proplatelets and human whole-blood platelet alpha-granules simultaneously probed for 2 different membrane proteins (VAMP-3 and VAMP-8), and multiple granular content proteins (bFGF, ENDO, TSP, VEGF) confirmed differential packaging of protein contents into alpha-granules. These data suggest that megakaryocytes differentially sort and package alpha-granule contents, which are preserved as alpha-granule subpopulations during proplatelet extension and platelet production.