Fibroblast growth factor receptor 1 (FGFR1) tyrosine phosphorylation regulates binding of FGFR substrate 2alpha (FRS2alpha) but not FRS2 to the receptor.
Fibroblast growth factor receptor 1 (FGFR1) tyrosine phosphorylation regulates binding of FGFR substrate 2alpha (FRS2alpha) but not FRS2 to the receptor.
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DOI：
10.1210/me.2007-0140
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发表时间：
2008
影响因子：
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通讯作者：
Yongyou Zhang;K. Mckeehan;Yongshun Lin;Jue Zhang;Fen Wang
中科院分区：
文献类型：
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作者：
Yongyou Zhang;K. Mckeehan;Yongshun Lin;Jue Zhang;Fen Wang
成纤维细胞生长因子（FGF）与FGF受体（FGFR）酪氨酸激酶的结合导致受体酪氨酸自磷酸化以及通过直接结合或通过衔接蛋白募集到受体的多个下游信号分子的磷酸化。FGFR底物2（FRS 2）家族由FRS 2 α和FRS 2 β两个成员组成，并且已显示将多种信号传导分子（包括Grb 2和Shp 2）募集至FGFR 1。为了更好地理解FRS 2如何与FGFR 1相互作用，在哺乳动物细胞中共表达FGFR 1和FRS 2重组蛋白进行体内结合测定。结果表明，全长FRS 2 α而非FRS 2 β与FGFR 1的相互作用通过受体激酶的活化而增强。仅由磷酸酪氨酸结合结构域（PTB）组成的截短的FRS 2 α突变体与FGFR 1组成性结合，表明PTB结构域下游的C末端序列抑制PTB-FGFR 1结合。FGFR 1激酶的失活和FGFR 1酪氨酸磷酸化位点的取代，而不是FRS 2 α，减少了FGFR 1与FRS 2 α的结合。结果表明，尽管FGFR 1的酪氨酸自磷酸化位点不构成FRS 2 α的结合位点，但这些残基的磷酸化对于与FRS 2 α的最佳相互作用是必不可少的。此外，已经证明FRS 2 α的Grb 2结合位点对于介导FGFR 1的信号以激活小鼠多配体蛋白聚糖1基因的FiRE增强子是必需的。结果，第一次，证明了特定的信号介导的Grb 2结合位点，并进一步了解FGF信号传输的衔接子水平。
Binding of the fibroblast growth factor (FGF) to the FGF receptor (FGFR) tyrosine kinase leads to receptor tyrosine autophosphorylation as well as phosphorylation of multiple downstream signaling molecules that are recruited to the receptor either by direct binding or through adaptor proteins. The FGFR substrate 2 (FRS2) family consists of two members, FRS2alpha and FRS2beta, and has been shown to recruit multiple signaling molecules, including Grb2 and Shp2, to FGFR1. To better understand how FRS2 interacted with FGFR1, in vivo binding assays with coexpressed FGFR1 and FRS2 recombinant proteins in mammalian cells were carried out. The results showed that the interaction of full-length FRS2alpha, but not FRS2beta, with FGFR1 was enhanced by activation of the receptor kinase. The truncated FRS2alpha mutant that was comprised only of the phosphotyrosine-binding domain (PTB) bound FGFR1 constitutively, suggesting that the C-terminal sequence downstream the PTB domain inhibited the PTB-FGFR1 binding. Inactivation of the FGFR1 kinase and substitutions of tyrosine phosphorylation sites of FGFR1, but not FRS2alpha, reduced binding of FGFR1 with FRS2alpha. The results suggest that although the tyrosine autophosphorylation sites of FGFR1 did not constitute the binding sites for FRS2alpha, phosphorylation of these residues was essential for optimal interaction with FRS2alpha. In addition, it was demonstrated that the Grb2-binding sites of FRS2alpha are essential for mediating signals of FGFR1 to activate the FiRE enhancer of the mouse syndecan 1 gene. The results, for the first time, demonstrate the specific signals mediated by the Grb2-binding sites and further our understanding of FGF signal transmission at the adaptor level.