The Key Laboratory of Molecular Medicine, Ministry of Education, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China.
PLoS One. 2012;7(7):e40566. doi: 10.1371/journal.pone.0040566. Epub 2012 Jul 10.
The protein-tyrosine phosphatase (PTP) Shp2 has been implicated in many immunoreceptor signaling pathways, but its role in immunoreceptor FcεRI signaling, which leads to the activation of mast cells and blood basophils, is still largely undefined. Using Shp2 knockdown RBL-2H3 (RBL) mast cells, we here reported that Shp2 is required for the activation of RBL cells induced by FcεRI. FcεRΙ-evoked degranulation, calcium mobilization, and synthesis of cytokine transcripts (IL-1β, IL-10, and monocyte chemoattractant protein 1 (MCP-1)) were reduced in Shp2 knockdown RBL cells. Signaling regulatory mechanism investigation using immunoblotting, immunoprecipitation, and GST pull-down assay reveals that the down-regulation of Shp2 expression in RBL cells leads to decreased activities of Fyn, PLCγ, JNK, p38MAPK, and Ras/Erk1/2 after FcεRΙ aggregation. Further studies suggest that Paxillin phosphoryaltion was also impaired, but PAG phosphorylation was normal after FcεRΙ stimulation as a consequence of the inhibition of Shp2 expression in RBL cells. Collectively, our data strongly indicate that Shp2 is essential for the activation of RBL cells in response to FcεRΙ aggregation. Shp2 regulates this process through Fyn and Ras with no involvement of PAG. In addition, we identify Paxillin as an indirect substrate of Shp2 in FcεRΙ-initiated signaling of RBL cells.
蛋白酪氨酸磷酸酶（PTP）Shp2 已被牵涉到许多免疫受体信号通路中，但它在免疫受体 FcεRI 信号中的作用，该信号导致肥大细胞和血液嗜碱性粒细胞的激活，在很大程度上仍未定义。使用 Shp2 敲低 RBL-2H3（RBL）肥大细胞，我们在此报告 Shp2 是 FcεRI 诱导的 RBL 细胞激活所必需的。FcεRΙ 引发的脱颗粒、钙动员和细胞因子转录物（IL-1β、IL-10 和单核细胞趋化蛋白 1（MCP-1））的合成在 Shp2 敲低的 RBL 细胞中减少。使用免疫印迹、免疫沉淀和 GST 下拉测定进行的信号调节机制研究表明，RBL 细胞中 Shp2 表达的下调导致 FcεRΙ 聚集后 Fyn、PLCγ、JNK、p38MAPK 和 Ras/Erk1/2 的活性降低。进一步的研究表明，Paxillin 的磷酸化也受损，但作为 RBL 细胞中 Shp2 表达抑制的结果，FcεRΙ 刺激后 PAG 磷酸化正常。总之，我们的数据强烈表明 Shp2 对于 FcεRI 聚集后 RBL 细胞的激活是必需的。Shp2 通过 Fyn 和 Ras 调节此过程，而不涉及 PAG。此外，我们确定 Paxillin 是 RBL 细胞中 FcεRI 起始信号中的 Shp2 的间接底物。
