Regulation of the Erk2-Elk1 signaling pathway and megakaryocytic differentiation of Bcr-Abl+ K562 leukemic cells by Gab2
Regulation of the Erk2-Elk1 signaling pathway and megakaryocytic differentiation of Bcr-Abl+ K562 leukemic cells by Gab2
复制标题
DOI：
10.1182/blood.v99.4.1388
复制
发表时间：
2002-02-15
期刊：
影响因子：
20.3
通讯作者：
Wu, J
中科院分区：
文献类型：
--
作者：
Dorsey, JF;Cunnick, JM;Wu, J
在慢性粒细胞白血病（CML）的急变期，Bcr-Abl（+）成粒细胞未能经历终末成熟。细胞外信号调节激酶（Erk）丝裂原活化蛋白（MAP）激酶已被证明介导骨髓细胞的终末分化。有趣的是，Bcr-Abl（+）CML细胞系建立从急变被发现有低Erk MAP激酶活性。在这项研究中，我们分析了Gab 2对接蛋白在Bcr-Abl（+）K562人CML细胞中Erk MAP激酶的调节作用。K562细胞中Gab 2的过表达导致c-fos、血清反应元件（SRE）启动子的转录激活，而SHP 2、Grb 2和CrkL的过表达没有影响。c-fos SRE转录活性被Gab 2激活需要酪氨酸604和SHP 2酪氨酸磷酸酶活性，酪氨酸604是Gab 2上的SHP 2对接位点。Elk 1、c-Jun和CHOP转录检测表明，Gab 2的过表达选择性地激活了Erk 2-Elk 1信号通路。为了确定在K562细胞中升高Gab 2水平的细胞后果，建立了野生型Gab 2（Gab 2 WT）和SHP 2结合缺陷型Gab 2（Gab 2 Tyr 604 Phe）的多西环素诱导表达的稳定细胞系。对这些细胞系的分析表明，诱导Gab 2 WT表达，而不是Gab 2 Tyr 604 Phe表达，导致Erk活化、生长停滞、细胞扩散和增大;巨核细胞/血小板谱系特异性整合素β 1b/β 3（CD 41/CD 61）的表达;以及巨核细胞/血小板蛋白的RNA上调。所有这些变化都是巨核细胞分化的特征。总之，这些结果揭示了Gab 2作为Erk MAP激酶激活和K562 CML细胞终末分化的限制性信号传导组分。(C)2002年，美国血液学会。
In the blast crisis phase of chronic myelogenous leukemia (CML), Bcr-Abl(+) myeloblasts fail to undergo terminal maturation. The extracellular signal-regulated kinase (Erk) mitogen-activated protein (MAP) kinase has been shown to mediate terminal differentiation of myeloid cells. Interestingly, Bcr-Abl(+) CML cell lines established from blast crisis were found to have low Erk MAP kinase activity. In this study, we analyzed the role of the Gab2 docking protein in regulation of the Erk MAP kinase in Bcr-Abl(+) K562 human CML cells. Overexpression of Gab2 in K562 cells resulted in transcriptional activation of the c-fos, serum response element (SRE) promoter, whereas overexpression of SHP2, Grb2, and CrkL had no effect. Activation of the c-fos SRE transcriptional activity by Gab2 required tyrosine 604, which is a SHP2 docking site on Gab2, and the SHP2 tyrosine phosphatase activity. Elk1, c-Jun, and CHOP transreporting assays indicated that overexpression of Gab2 selectively activated the Erk2-Elk1 signaling pathway. To determine cellular consequences of elevating the Gab2 level In K562 cells, stable cell lines for doxycycline-inducible expression of the wild-type Gab2 (Gab2WT) and an SHP2-binding defective Gab2 (Gab2Tyr604Phe) were established. Analysis of these cell lines indicated that Induction of Gab2WT expression, but not Gab2Tyr604Phe expression, led to Erk activation, growth arrest, cell spreading, and enlargement; expression of megakaryocyte/platelet lineage-specific Integrins alphallb/beta3 (CD41/CD61); and upregulation of RNA for megakaryocyte/platelet proteins. All of these changes are characteristics of megakaryocytic differentiation. Together, these results reveal Gab2 as a limiting signaling component for Erk MAP kinase activation and terminal differentiation of K562 CML cells. (C) 2002 by The American Society of Hematology.