Kit- and FcεRI-induced differential phosphorylation of the transmembrane adaptor molecule NTAL/LAB/LAT2 allows flexibility in its scaffolding function in mast cells
Kit- and FcεRI-induced differential phosphorylation of the transmembrane adaptor molecule NTAL/LAB/LAT2 allows flexibility in its scaffolding function in mast cells
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DOI：
10.1016/j.cellsig.2007.10.013
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发表时间：
2008-01-01
影响因子：
4.8
通讯作者：
Gilfillan, Alasdair M.
中科院分区：
文献类型：
--
作者：
Iwaki, Shoko;Spicka, Jiri;Gilfillan, Alasdair M.
跨膜适配器蛋白(TRAP)NTAL在Fc epsilon RI聚集后在肥大细胞中被磷酸化，从而与LAT合作诱导脱颗粒。Kit配体，干细胞因子(SCF)，加强了抗原诱导的脱颗粒，这似乎也是NTAL依赖的。然而，Kit和Fc epsilon RI似乎使用不同的机制来诱导ntal磷酸化。因此，我们研究了负责的激酶是否选择性地磷酸化NTAL中不同的酪氨酸，并探索其对下游信号转导的影响。而Fc epsilon RI需要Lyn和Syk进行ntal的磷酸化，而Kit似乎直接使ntal磷酸化。此外，与NTAL构建物共转染的研究表明，Lyn、Syk和Kit在NTAL中磷酸化不同的酪氨酸。主要被Syk磷酸化的酪氨酸被认为是Grb2结合位点，而Lyn和Kit则磷酸化了这些基序内外的其他酪氨酸。下拉研究表明，PLC Gamma(1)I与两个末端Syk磷酸化的Grb2结合位点有关，这有助于解释观察到的抗原诱导的钙信号减弱和NAL击倒的人肥大细胞脱颗粒的原因。本文报道的观察结果支持这样的结论，即特定受体可能以不同的方式利用NTAL来传递替代信号，这表明Trap的功能具有以前未被认识到的灵活性。(C)2007 Elsevier Inc.保留所有权利。
The transmembrane adaptor protein (TRAP), NTAL, is phosphorylated in mast cells following Fc epsilon RI aggregation whereby it cooperates with LAT to induce degranulation. The Kit ligand, stem cell factor (SCF), enhances antigen-induced degranutation and this also appears to be NTAL-dependent. However, Kit and Fc epsilon RI appear to utilize different mechanisms to induce NTAL phosphorylation. Thus, we examined whether the responsible kinases selectively phosphorylated distinct tyrosines in NTAL and explored the implications for downstream signaling. Whereas Fc epsilon RI required Lyn and Syk for NTAL phosphorylation, Kit appeared to directly phosphorylate NTAL. Furthermore, co-transfection studies with NTAL constructs revealed that Lyn, Syk, and Kit phosphorylate different tyrosines in NTAL. The tyrosines principally phosphorylated by Syk were recognized as Grb2-binding sites, whereas Lyn and Kit phosphorylated other tyrosines, both inside and outside of these motifs. Pull down studies revealed that PLC gamma(1) I associated with the two terminal Syk-phosphorylated Grb2-binding sites, which would help to explain the observed decrease in antigen-induced calcium signal and degranulation in NTAL-knock down-human mast cells. The observations reported herein support the conclusion that NTAL may be differentially utilized by specific receptors for relaying alternative signals and this suggests a flexibility in the function of TRAPs not previously appreciated. (C) 2007 Elsevier Inc. All rights reserved.