Growth and maturation of megakaryocytes is regulated by Lnk/Sh2b3 adaptor protein through crosstalk between cytokine- and integrin-mediated signals
Growth and maturation of megakaryocytes is regulated by Lnk/Sh2b3 adaptor protein through crosstalk between cytokine- and integrin-mediated signals
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DOI：
10.1016/j.exphem.2008.02.004
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发表时间：
2008-07-01
影响因子：
2.6
通讯作者：
Takaki, Satoshi
中科院分区：
文献类型：
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作者：
Takizawa, Hitoshi;Eto, Koji;Takaki, Satoshi
Objective.巨核细胞的分化和成熟受多种细胞因子和生长因子的调控。然而，调节血小板从MK释放的机制还不清楚。在这里，我们研究了Lnk/Sh 2b 3，一种细胞内衔接蛋白，在巨核细胞生成中的作用。采用集落形成单位法测定野生型和Lnk（-/-）小鼠骨髓中MK祖细胞数量及其对血小板生成素（TPO）的敏感性。用TPO刺激BM衍生的野生型或Lnk（-/-）MK，生化分析信号分子的活化，并通过加入血管细胞粘附分子（VCAM-1）研究整合素刺激对TPO信号的影响。流式细胞术检测VCAM-1对MKs血小板生成的影响，延时显微镜观察血小板形态学变化。由于祖细胞对TPO的敏感性增强，Lnk（-/-）小鼠显示血小板和成熟MK升高。在Lnk（-/-）MK中，LPO诱导的Erk 1/2磷酸化增强并延长，而信号转导子和转录激活子（Stat）3、Stat 5和Akt的激活正常。野生型MK，而不是在VCAM-1上的Lnk（-/-）MK中，在TPO刺激后显示出减少的Stat 5磷酸化和丝裂原活化蛋白激酶活化。此外，培养物中VCAM的存在加速了成熟野生型MK的自发性血小板释放，但对Lnk（-/-）MK无影响。结果表明，通过整合素与粘附分子的MK接触可能有助于血小板释放，这是在Lnk介导的调节下的Stat-5激活，并显示Lnk在由细胞粘附控制的反应中起作用，以及在整合素和丝氨酸介导的信号传导之间的串扰中起作用。(c)2008 ISEH -血液学和干细胞学会。爱思唯尔公司出版
Objective. Various cytokines and growth factors control the differentiation and maturation of megakaryocytes (MKs). However, the mechanism regulating platelet release from MKs is not well understood. Here, we investigated a role of Lnk/Sh2b3, an intracellular adaptor protein, in megakaryopoiesis.Materials and Methods. Number of MK progenitor in bone marrow (BM) of wild-type or Lnk(-/-) mice and their sensitivity to thrombopoietin (TPO) were determined in colony-forming unit assay. Using BM-derived wild-type or Lnk(-/-) MKs stimulated with TPO, activation of the signaling molecules was biochemically analyzed and effect of integrin stimulation on TPO signals was studied by addition of vascular cell adhesion molecule (VCAM-1). Platelet production from MKs in the presence of VCAM-1 was counted by flow cytometry and their morphological change was observed by time-lapse microscopy.Results. Lnk(-/-) mice showed elevated platelets and mature MKs due to enhanced sensitivity of progenitors to TPO. Erk1/2 phosphorylation induced by TPO was augmented and prolonged in Lnk(-/-) MKs while activation of signal transducers and activators of transcription (Stat)3, Stat5, and Akt was normal. Wild-type MKs, but not in Lnk(-/-) MKs on VCAM-1 showed reduced Stat5 phosphorylation and mitogen-activated protein kinases activation upon stimulation with TPO. Additionally, the presence of VCAM in culture accelerated spontaneous platelet release from mature wild-type MKs, but not from Lnk(-/-) MKs.Conclusions. Results suggest that contact of MKs with adhesion molecules via integrins might contribute to platelet release, which is under Lnk-mediated regulation of Stat-5 activation and show that Lnk functions in responses controlled by cell adhesion and in crosstalk between integrin- and cytokine-mediated signaling. (c) 2008 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc.