Platelet Activation Receptor CLEC-2 Regulates Blood/Lymphatic Vessel Separation by Inhibiting Proliferation, Migration, and Tube Formation of Lymphatic Endothelial Cells
Platelet Activation Receptor CLEC-2 Regulates Blood/Lymphatic Vessel Separation by Inhibiting Proliferation, Migration, and Tube Formation of Lymphatic Endothelial Cells
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DOI：
10.1074/jbc.m111.329987
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发表时间：
2012-06-22
影响因子：
4.8
通讯作者：
Ozaki, Yukio
中科院分区：
文献类型：
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作者：
Osada, Makoto;Inoue, Osamu;Ozaki, Yukio
血小板活化受体CLEC-2在血栓形成/止血、肿瘤转移和淋巴管生成中起关键作用，尽管其在血栓形成/止血中的作用仍存在争议。CLEC-2的内源性配体podoplanin在淋巴管内皮细胞（LEC）中表达。我们和其他人已经报道了CLEC-2缺陷在与充满血液的血管相关的小鼠胚胎/新生儿阶段是致命的，表明CLEC-2对于血液/淋巴管分离是必需的。然而，其机制，以及血小板中的CLEC-2是否是这种分离所必需的，仍然未知。我们发现，从血小板中特异性缺失CLEC-2导致血液/淋巴管的错误连接。CLEC-2（+/+）血小板可抑制LEC的迁移、增殖和管腔形成，但对人脐静脉内皮细胞无影响。此外，从活化血小板的上清液显着抑制这三个功能的LEC，这表明释放的颗粒内容物调节血液/淋巴管分离。骨形态蛋白-9（BMP-9），我们发现它存在于血小板中并在激活时释放，似乎在调节LEC功能中起关键作用。只有BMP-9抑制管形成，虽然其他释放包括转化生长因子-β和血小板因子4抑制增殖和/或迁移。我们提出血小板通过抑制LEC的增殖、迁移和管形成来调节血液/淋巴管分离，这主要是因为CLEC-2/podoplanin相互作用激活后BMP-9的释放。
The platelet activation receptor CLEC-2 plays crucial roles in thrombosis/hemostasis, tumor metastasis, and lymphangiogenesis, although its role in thrombosis/hemostasis remains controversial. An endogenous ligand for CLEC-2, podoplanin, is expressed in lymphatic endothelial cells (LECs). We and others have reported that CLEC-2-deficiency is lethal at mouse embryonic/neonatal stages associated with blood-filled lymphatics, indicating that CLEC-2 is essential for blood/lymphatic vessel separation. However, its mechanism, and whether CLEC-2 in platelets is necessary for this separation, remains unknown. We found that specific deletion of CLEC-2 from platelets leads to the misconnection of blood/lymphatic vessels. CLEC-2(+/+) platelets platelets, but not by CLEC-2(-/-) platelets, inhibited LEC migration, proliferation, and tube formation but had no effect on human umbilical vein endothelial cells. Additionally, supernatants from activated platelets significantly inhibited these three functions in LECs, suggesting that released granule contents regulate blood/lymphatic vessel separation. Bone morphologic protein-9 (BMP-9), which we found to be present in platelets and released upon activation, appears to play a key role in regulating LEC functions. Only BMP-9 inhibited tube formation, although other releasates including transforming growth factor-beta and platelet factor 4 inhibited proliferation and/or migration. We propose that platelets regulate blood/lymphatic vessel separation by inhibiting the proliferation, migration, and tube formation of LECs, mainly because of the release of BMP-9 upon activation by CLEC-2/podoplanin interaction.