Row Paula E, Clague Michael J, Urbé Sylvie
Physiological Laboratory, University of Liverpool, Crown St., Liverpool L69 3BX, UK.
Biochem J. 2005 Aug 1;389(Pt 3):629-36. doi: 10.1042/BJ20050067.
Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate) and STAM (signal-transducing adaptor molecule) form a heterodimeric complex that associates with endosomal membranes and is tyrosine-phosphorylated in response to a variety of growth factors including EGF (epidermal growth factor), HGF (hepatocyte growth factor) and PDGF (platelet-derived growth factor). Phosphorylation of the Hrs-STAM complex requires receptor endocytosis. We show that an intact UIM (ubiquitin interaction motif) within Hrs is a conserved requirement for Hrs phosphorylation downstream of both EGF and HGF stimulations. Consistent with this, expression of a dominant-negative form of the E3 ubiquitin ligase, c-Cbl, inhibits EGF- and HGF-dependent Hrs phosphorylation. Despite this conservation, kinase inhibitor profiles using PP1 (4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine) and SU6656 indicate that distinct non-receptor tyrosine kinases couple EGF, HGF and PDGF stimulation with the tyrosine phosphorylation of the Hrs-STAM complex. Crucially, analysis with phospho-specific antibodies indicates that these kinases generate a signal-specific, combinatorial phosphorylation profile of the Hrs-STAM complex, with the potential of diversifying tyrosine kinase receptor signalling through a common element.
肝细胞生长因子调节的酪氨酸激酶底物（Hrs）和信号转导衔接分子（STAM）形成一种异源二聚体复合物，该复合物与内体膜结合，并在响应包括表皮生长因子（EGF）、肝细胞生长因子（HGF）和血小板衍生生长因子（PDGF）在内的多种生长因子时发生酪氨酸磷酸化。Hrs-STAM复合物的磷酸化需要受体的内吞作用。我们发现，Hrs内完整的泛素相互作用基序（UIM）是EGF和HGF刺激下游Hrs磷酸化的保守必需条件。与此一致的是，E3泛素连接酶c-Cbl的显性负性形式的表达抑制了EGF和HGF依赖性的Hrs磷酸化。尽管存在这种保守性，但使用PP1（4-氨基-5-（4-甲基苯基）-7-（叔丁基）吡唑并[3,4-d]嘧啶）和SU6656的激酶抑制剂谱表明，不同的非受体酪氨酸激酶将EGF、HGF和PDGF刺激与Hrs-STAM复合物的酪氨酸磷酸化偶联起来。至关重要的是，使用磷酸特异性抗体的分析表明，这些激酶产生了Hrs-STAM复合物的信号特异性组合磷酸化谱，具有通过一个共同元件使酪氨酸激酶受体信号多样化的潜力。
