Coordinated regulation of the tyrosine phosphorylation of Cbl by Fyn and Syk tyrosine kinases
Coordinated regulation of the tyrosine phosphorylation of Cbl by Fyn and Syk tyrosine kinases
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DOI：
10.1074/jbc.273.15.8867
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发表时间：
1998-04-10
影响因子：
4.8
通讯作者：
Liu, YC
中科院分区：
文献类型：
--
作者：
Deckert, M;Elly, C;Liu, YC
T细胞抗原受体(TCR)-CD3复合体的交联会诱导Src(Lck和Fyn)和Syk(Syk和Zap-70)家族蛋白酪氨酸激酶(PTKs)的快速酪氨酸磷酸化，进而使多种细胞内底物磷酸化。CBL是一种重要的PTK底物，提示它在早期信号转导事件中起着关键作用。然而，上游蛋白酪氨酸激酶对T细胞Cbl功能和酪氨酸磷酸化的调节仍然知之甚少。在本研究中，我们使用遗传学和生化方法证明了Cb1分别通过其N-末端和C-末端区域与Syk和Fyn直接相互作用。Syk的Tyr-316是与Cbl相互作用所必需的，也是Cb1最大酪氨酸磷酸化所必需的。然而，野生型Syk和Y316F突变的Syk在体内都能很好地磷酸化Cbl的C端片段，这表明在Syk诱导的Cbl酪氨酸磷酸化过程中存在一种不依赖于N端的替代机制，这种机制似乎涉及Fyn，因为除了与Cbl的C端区域相关外，Fyn还与Syk相关，并增强了Syk诱导的Cbl的酪氨酸磷酸化，这些发现表明Fyn是一种接头蛋白，促进Syk和Cbl之间的相互作用，并提示Src和Syk家族PTKs协调调节Cbl的酪氨酸磷酸化。
Cross-linking of the T cell antigen receptor (TCR)-CD3 complex induces rapid tyrosine phosphorylation and activation of Src (Lck and Fyn) and Syk (Syk and Zap-70) family protein tyrosine kinases (PTKs) which, in turn, phosphorylate multiple intracellular substrates. Cbl is a prominent PTK substrate suggesting a pivotal role for it in early signal transduction events. However, the regulation of Cbl function and tyrosine phosphorylation in T cells by upstream PTKs remains poorly understood. In the present study, we used genetic and biochemical approaches to demonstrate that Cbl directly interacts with Syk and Fyn via its N-terminal and C-terminal regions, respectively. Tyr-316 of Syk was required for the interaction with Cbl as well as for the maximal tyrosine phosphorylation of Cbl. However, both wild-type Syk and Y316F-mutated Syk phosphorylated equally well the C-terminal fragment of Cbl in vivo, suggesting the existence of an alternative, N terminus-independent mechanism for the Syk-induced tyrosine phosphorylation of Cbl, This mechanism appears to involve Fyn, since, in addition to its association with the C-terminal region of Cbl, Fyn also associated with Syk and enhanced the Syk-induced tyrosine phosphorylation of Cbl, These findings implicate Fyn as an adaptor protein that facilitates the interaction between Syk and Cbl, and suggest that Src and Syk family PTKs coordinately regulate the tyrosine phosphorylation of Cbl.