Hamawy M M, Mergenhagen S E, Siraganian R P
Laboratory of Immunology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
J Biol Chem. 1993 Apr 5;268(10):6851-4.
The aggregation of the high affinity IgE receptor (Fc epsilon RI) in adherent rat basophilic leukemia (RBL-2H3) cells induces the tyrosine phosphorylation of several proteins. We examined whether focal adhesion-associated tyrosine kinase, pp125FAK, is one of these proteins. Anti-pp125FAK monoclonal antibody immunoblotted and precipitated a 115-kDa tyrosine-phosphorylated protein. In the absence of Fc epsilon RI aggregation, pp125FAK was tyrosine-phosphorylated only in adherent cells. Aggregating Fc epsilon RI in adherent cells markedly enhanced tyrosine phosphorylation of pp125FAK. This increase was detectable within 1 min of Fc epsilon RI aggregation and was maximal by 15 min. In contrast, in nonadherent cells Fc epsilon RI aggregation did not induce tyrosine phosphorylation of pp125FAK. The enhanced influx of calcium by calcium ionophore or the activation of protein kinase C by phorbol myristate acetate induced tyrosine phosphorylation of pp125FAK only in adherent cells. Thus, Fc epsilon RI-induced tyrosine phosphorylation of pp125FAK could be mediated by the activation of protein kinase C and/or the induction of calcium influx. The data indicate that cell adherence is essential for Fc epsilon RI-induced tyrosine phosphorylation of pp125FAK.
高亲和力IgE受体（FcεRI）在贴壁大鼠嗜碱性粒细胞白血病（RBL-2H3）细胞中的聚集可诱导多种蛋白质的酪氨酸磷酸化。我们研究了粘着斑相关酪氨酸激酶pp125FAK是否是这些蛋白质之一。抗pp125FAK单克隆抗体通过免疫印迹法沉淀出一种115 kDa的酪氨酸磷酸化蛋白。在不存在FcεRI聚集的情况下，pp125FAK仅在贴壁细胞中发生酪氨酸磷酸化。在贴壁细胞中聚集FcεRI可显著增强pp125FAK的酪氨酸磷酸化。这种增加在FcεRI聚集后1分钟内即可检测到，15分钟时达到最大值。相反，在非贴壁细胞中，FcεRI聚集不会诱导pp125FAK的酪氨酸磷酸化。钙离子载体增强钙离子内流或佛波酯肉豆蔻酸酯激活蛋白激酶C仅在贴壁细胞中诱导pp125FAK的酪氨酸磷酸化。因此，FcεRI诱导的pp125FAK酪氨酸磷酸化可能是由蛋白激酶C的激活和/或钙离子内流的诱导介导的。数据表明，细胞贴壁对于FcεRI诱导的pp125FAK酪氨酸磷酸化至关重要。
