CLEC-2 expression is maintained on activated platelets and on platelet microparticles
CLEC-2 expression is maintained on activated platelets and on platelet microparticles
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DOI：
10.1182/blood-2014-05-572818
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发表时间：
2014-10-02
期刊：
影响因子：
20.3
通讯作者：
Watson, Steve P.
中科院分区：
文献类型：
--
作者：
Gitz, Eelo;Pollitt, Alice Y.;Watson, Steve P.
c型凝集素样受体clc -2通过基于血细胞免疫受体酪氨酸的激活基序（hemITAM）介导血小板活化。clc -2启动Src-和syk依赖性信号级联，与2种血小板ITAM受体：糖蛋白（GP） VI和Fc γ RIIa密切相关。ITAM受体的激活可诱导Fc γ RIIa中GPVI的脱落和ITAM结构域的蛋白水解。在本研究中，我们制备了针对人CLEC-2的单克隆抗体，并使用这些抗体来测量静止血小板和刺激血小板以及其他造血细胞上CLEC-2的表达。我们发现，CLEC-2局限于平均拷贝数为每个细胞2000的血小板，并且CLEC-2的激活诱导GPVI和Fc γ RIIa的蛋白水解裂解，而不是自身的裂解。我们进一步表明，巨核细胞培养物和富血小板血浆中的CD41（+）微颗粒（主要来自健康供体的巨核细胞）表达CLEC-2和GPVI，而来自活化血小板的微颗粒仅表达CLEC-2。类风湿关节炎是一种与微颗粒产生增加相关的炎症性疾病，其患者血浆中表达CLEC-2但不表达GPVI的微颗粒水平升高。因此，与血小板ITAM受体不同，CLEC-2不受蛋白水解的调节，可用于监测血小板衍生的微粒。
The C-type lectin-like receptor CLEC-2 mediates platelet activation through a hemimmunoreceptor tyrosine-based activation motif (hemITAM). CLEC-2 initiates a Src- and Syk-dependent signaling cascade that is closely related to that of the 2 platelet ITAM receptors: glycoprotein (GP) VI and Fc gamma RIIa. Activation of either of the ITAMreceptors induces shedding of GPVI and proteolysis of the ITAM domain in Fc gamma RIIa. In the present study, we generated monoclonal antibodies against human CLEC-2 and used these to measure CLEC-2 expression on resting and stimulated platelets and on other hematopoietic cells. We show that CLEC-2 is restricted to platelets with an average copy number of similar to 2000 per cell and that activation of CLEC-2 induces proteolytic cleavage of GPVI and Fc gamma RIIa but not of itself. We further show that CLEC-2 and GPVI are expressed on CD41(+) microparticles in megakaryocyte cultures and in platelet-rich plasma, which are predominantly derived from megakaryocytes in healthy donors, whereas microparticles derived from activated platelets only express CLEC-2. Patients with rheumatoid arthritis, an inflammatory disease associated with increased microparticle production, had raised plasma levels of microparticles that expressed CLEC-2 but not GPVI. Thus, CLEC-2, unlike platelet ITAM receptors, is not regulated by proteolysis and can be used to monitor platelet-derived microparticles.