Synthesis and secretion of von Willebrand factor and fibronectin in megakaryocytes at different phases of maturation.
Synthesis and secretion of von Willebrand factor and fibronectin in megakaryocytes at different phases of maturation.
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不同成熟阶段巨核细胞中冯维勒布兰德因子和纤连蛋白的合成和分泌。
DOI：
10.1161/01.atv.17.4.797
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Bennett,V
中科院分区：
文献类型：
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作者：
Schick,PK;Walker,J;Profeta,B;Denisova,L;Bennett,V
我们的目标是确定巨核细胞成熟过程中的生化特征，这些特征对血小板组装和释放到循环中至关重要，并引入巨核细胞的生化标志物。为了实现这些目标，我们研究了纤连蛋白（FN）和血管性血友病因子（vWF），它们是由巨核细胞合成的大型粘附蛋白，储存在α颗粒中，并被认为在止血中具有基本作用。研究表明，vWF主要在成熟的巨核细胞中合成，其合成的vWF是未成熟巨核细胞的7.5倍。布雷菲德菌素A，阻止蛋白质从粗面内质网（RER）的出口，抑制vWF多聚体的形成，但不影响成熟巨核细胞中单体和二聚体的合成。这些数据与RER中vWF二聚体的形成以及反式和后高尔基体中vWF多聚体的组装一致。检测到260-kD和275-kD pro-vWF的合成。然而，275-kD pro-vWF和220-kD成熟vWF的合成仅在2小时后明显，表明新生vWF通过RER的转运时间约为2小时。在巨核细胞中证实了vWF的组成性分泌。成熟和未成熟巨核细胞分别分泌约14.5%和4.6%的合成vWF。与此相反，FN单体和二聚体的合成建立在未成熟的巨核细胞，它们的合成在成熟的巨核细胞是非常相似的。巨核细胞未见FN组成性分泌。布雷菲德菌素A不抑制FN二聚体的合成;因此，FN二聚体的形成发生在RER中。vWF和FN在巨核细胞成熟的不同阶段合成，并且只有vWF由巨核细胞组成性分泌的证明提供了与α颗粒形成和可能的骨髓基质组装相关的新信息。
Our goals have been to define the biochemical characteristics of megakaryocytes during maturation that are critical for platelet assembly and release into the circulation and to introduce biochemical markers for megakaryocytes. To achieve these goals, we have studied fibronectin (FN) and von Willebrand factor (vWF), which are large adhesive proteins that are synthesized by megakaryocytes, stored in alpha granules, and thought to have a fundamental role in hemostasis. The study demonstrated that vWF is primarily synthesized in mature megakaryocytes, which synthesized 7.5 times more vWF than immature megakaryocytes. Brefeldin A, which blocks the exit of proteins from the rough endoplasmic reticulum (RER), inhibited the formation of vWF multimers but did not affect the synthesis of monomers and dimers in mature megakaryocytes. These data are consistent with the formation of vWF dimers in the RER and the assembly of vWF multimers in the trans- and post-golgi. The synthesis of both the 260-kD and 275-kD pro-vWF was detected. However, the synthesis of 275-kD pro-vWF and 220-kD mature vWF was only evident after 2 hours, suggesting that the transit time of nascent vWF through the RER is about 2 hours. Constitutive secretion of vWF was demonstrated in megakaryocytes. About 14.5% and 4.6% of synthesized vWF was secreted by mature and immature megakaryocytes, respectively. In contrast, the synthesis of FN monomers and dimers was established in immature megakaryocytes, and their synthesis in mature megakaryocytes was very similar. Constitutive secretion of FN was not seen in megakaryocytes. Brefeldin A did not inhibit the synthesis of FN dimers; thus, formation of FN dimers occurs in the RER. The demonstration that vWF and FN are synthesized at different phases of megakaryocyte maturation and that only vWF is constitutively secreted by megakaryocytes provides new information relevant to alpha granule formation and possibly bone marrow matrix assembly.