Program of Host-Pathogen Interactions, University of California, San Francisco, CA, USA.
Blood. 2011 Oct 20;118(16):4377-83. doi: 10.1182/blood-2011-02-338053. Epub 2011 Aug 24.
A key event and potential therapeutic target in allergic and asthmatic diseases is signaling by the IgE receptor FcεRI, which depends on its interactions with Src family kinases (SFK). Here we tested the hypothesis that glycosylphosphatidylinositiol-anchored proteins (GPI-AP) are involved in FcεRI signaling, based on previous observations that GPI-AP colocalize with and mediate activation of SFK. We generated mice with a hematopoietic cell-specific GPI-AP deficiency by targeted disruption of the GPI biosynthesis gene PigA. In these mice, IgE-mediated passive cutaneous anaphylaxis was largely abolished. PigA-deficient mast cells cultured from these mice showed impaired degranulation in response to stimulation with IgE and antigen in vitro, despite normal IgE binding and antigen-induced FcεRI aggregation. On stimulation of these cells with IgE and antigen, coprecipitation of the FcεRI α-chain with the γ-chain and β-chain was markedly reduced. As a result, IgE/antigen-induced FcεRI-Lyn association and γ-chain tyrosine phosphorylation were both impaired in PigA-deficient cells. These data provide genetic evidence for an unanticipated key role of GPI-AP in FcεRI interchain interactions and early FcεRI signaling events, necessary for antigen-induced mast cell degranulation.
在过敏和哮喘疾病中，IgE 受体 FcεRI 的信号转导是一个关键事件和潜在的治疗靶点，它依赖于其与Src 家族激酶 (SFK) 的相互作用。基于先前观察到的糖基磷脂酰肌醇锚定蛋白 (GPI-AP) 与 SFK 的共定位和激活有关的假设，我们在此测试了 GPI-AP 是否参与 FcεRI 信号转导。我们通过靶向破坏 GPI 生物合成基因 PigA ，生成了造血细胞特异性 GPI-AP 缺陷小鼠。在这些小鼠中，IgE 介导的被动皮肤过敏反应被大大消除。从这些小鼠中培养的 PigA 缺陷肥大细胞在体外对 IgE 和抗原的刺激显示出脱颗粒受损，尽管 IgE 结合和抗原诱导的 FcεRI 聚集正常。在这些细胞受到 IgE 和抗原的刺激时，FcεRI α 链与 γ 链和 β 链的共沉淀明显减少。结果，IgE/抗原诱导的 FcεRI-Lyn 关联和 γ 链酪氨酸磷酸化在 PigA 缺陷细胞中均受损。这些数据为 GPI-AP 在 FcεRI 链间相互作用和早期 FcεRI 信号事件中的预期关键作用提供了遗传证据，这些相互作用和事件对于抗原诱导的肥大细胞脱颗粒是必需的。
