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首页> 外文期刊>The Journal of Experomental Medicine >Transfection of Syk protein tyrosine kinase reconstitutes high affinity IgE receptor-mediated degranulation in a Syk-negative variant of rat basophilic leukemia RBL-2H3 cells.
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Transfection of Syk protein tyrosine kinase reconstitutes high affinity IgE receptor-mediated degranulation in a Syk-negative variant of rat basophilic leukemia RBL-2H3 cells.

机译：Syk蛋白酪氨酸激酶的转染在大鼠嗜碱性白血病RBL-2H3细胞的Syk阴性变体中重建了高亲和力IgE受体介导的脱粒。

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摘要

Aggregation of the high affinity receptor for immunoglobulin E (Fc epsilon RI) on mast cells results in rapid tyrosine phosphorylation and activation of Syk, a cytoplasmic protein tyrosine kinase. To examine the role of Syk in the Fc epsilon RI signaling pathway, we identified a variant of RBL-2H3 cells that has no detectable Syk by immunoblotting and by in vitro kinase reactions. In these Syk-deficient TB1A2 cells, aggregation of Fc epsilon RI induced no histamine release and no detectable increase in total cellular protein tyrosine phosphorylation. However, stimulation of these cells with the calcium ionophore did induce degranulation. Fc epsilon RI aggregation induced tyrosine phosphorylation of the beta and gamma subunits of the receptor, but no increase in the tyrosine phosphorylation of phospholipase C-gamma 1 and phospholipase C-gamma 2 and no detectable increase in intracellular free Ca2+ concentration. By transfection, cloned lines were established with stable expression of Syk. In these reconstituted cells, Fc epsilon RI aggregation induced tyrosine phosphorylation of phospholipase C-gamma 1 and phospholipase C-gamma 2, an increase in intracellular free Ca2+ and histamine release. These results demonstrate that Syk plays a critical role in the early Fc epsilon RI-mediated signaling events. It further demonstrates that Syk activation occurs downstream of receptor phosphorylation, but upstream of most of the Fc epsilon RI-mediated protein tyrosine phosphorylations.
机译：肥大细胞上免疫球蛋白E（Fc epsilon RI）的高亲和力受体的聚集导致酪氨酸快速磷酸化和Syk（一种细胞质蛋白酪氨酸激酶）的活化。若要检查Syk在FcεRI信号传导途径中的作用，我们鉴定了一种RBL-2H3细胞变体，该变体通过免疫印迹和体外激酶反应检测不到Syk。在这些Syk缺陷的TB1A2细胞中，FcεRI的聚集不诱导组胺释放，总细胞蛋白酪氨酸磷酸化也没有可检测的增加。然而，用钙离子载体刺激这些细胞确实引起脱粒。 Fc epsilon RI聚集诱导受体的β和γ亚基的酪氨酸磷酸化，但磷脂酶C-γ1和磷脂酶C-γ2的酪氨酸磷酸化没有增加，并且细胞内游离Ca2 +浓度没有可检测到的增加。通过转染，建立了具有稳定表达Syk的克隆系。在这些重组细胞中，FcεRI聚集体诱导磷脂酶C-γ1和磷脂酶C-γ2的酪氨酸磷酸化，增加细胞内游离Ca2 +和组胺的释放。这些结果表明Syk在早期FcεRI介导的信号转导事件中起关键作用。它进一步证明，Syk激活发生在受体磷酸化的下游，但在大多数FcεRI介导的蛋白酪氨酸磷酸化的上游。

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