Regulation of Cbl phosphorylation by the Abl tyrosine kinase and the Nck SH2/SH3 adaptor
Regulation of Cbl phosphorylation by the Abl tyrosine kinase and the Nck SH2/SH3 adaptor
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DOI：
10.1038/sj.onc.1204528
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发表时间：
2001-07-05
期刊：
影响因子：
8
通讯作者：
Mayer, BJ
中科院分区：
文献类型：
--
作者：
Miyoshi-Akiyama, T;Aleman, LM;Mayer, BJ
Cbl 原癌基因产物因响应多种刺激而被酪氨酸磷酸化。 Cbl 和 Abl 非受体酪氨酸激酶均与 SH2/SH3 接头 Nck 的 SH3 结构域结合，并且是 Nck 功能的候选效应物。 Cbl、Abl 和 Nck 之间也可能存在许多其他 SH2 和 SH3 结构域介导的相互作用。我们发现这三种信号蛋白在哺乳动物细胞中过表达时会关联，并且可以调节彼此的活性。 mt Cbl 与 c-Abl 的 Go 表达（其活性在体内通常受到抑制）导致 Cbl 广泛的 Abl 依赖性磷酸化。c-Abl 的 ifs 磷酸化需要 Cbl 的主要富含脯氨酸的区域，但组成型激活的 Abl 突变体不需要，这表明 Cbl 通过接合其 SH3 结构域来激活 c-Abl。 Cbl 的有效磷酸化及其与 Abl 的稳定结合需要 Abl 的 SH2 结构域，这表明 SH2-磷酸酪氨酸相互作用阻止活性 Abl 从 Cbl 解离。我们还表明，Nck 的过表达可以抑制体内 Abl 对 Cbl 的磷酸化。 Nck 突变体的研究表明，Nck SH2 结构域负责抑制 Abl 对 Cbl 和 Nck 本身的活性，最有可能是通过与 Abl SH2 竞争酪氨酸磷酸化结合位点。
The Cbl proto-oncogene product is tyrosine phosphorylated in response to a wide variety of stimuli. Cbl and the Abl nonreceptor tyrosine kinase both bind to SH3 domains from the SH2/SH3 adaptor Nck, and are candidate effecters for Nck function. Numerous additional SH2- and SH3-domain-mediated interactions are also possible between Cbl, Abl, and Nck, We find that these three signaling proteins associate when overexpressed in mammalian cells and can regulate each other's activity. Go-expression of mt Cbl together with c-Abl, the activity of which is normally repressed in vivo, led to extensive Abl-dependent phosphorylation of Cbl, The major proline-rich region of Cbl was required for ifs phosphorylation by c-Abl, but not by a constitutively activated Abl mutant, suggesting Cbl activates c-Abl by engaging its SH3 domain. Efficient phosphorylation of Cbl and its stable association with Abl required the SH2 domain of Abl, suggesting that SH2-phosphotyrosine interactions prevent dissociation of active Abl from Cbl, We also show that overexpression of Nck could repress the phosphorylation of Cbl by Abl in vivo. Studies with Nck mutants suggested that the Nck SH2 domain is responsible for inhibiting the activity of Abl toward both Cbl and Nck itself, most likely by competing with the Abl SH2 for tyrosine-phosphorylated binding sites.