The membrane-anchoring domain of epidermal growth factor receptor ligands dictates their ability to operate in juxtacrine mode
The membrane-anchoring domain of epidermal growth factor receptor ligands dictates their ability to operate in juxtacrine mode
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DOI：
10.1091/mbc.e04-11-0994
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发表时间：
2005-06-01
影响因子：
3.3
通讯作者：
Wiley, HS
中科院分区：
文献类型：
--
作者：
Dong, JY;Opresko, LK;Wiley, HS
表皮生长因子受体(EGFR)的所有配体都是作为膜锚定前体合成的。以前的工作表明，一些配体，如EGF，必须通过蛋白水解性释放才能发挥活性，而另一些配体，如肝素结合的EGF样生长因子(HB-EGF)，可以在仍然锚定在膜上的情况下发挥作用(即旁分泌信号)。为了探索配体活性差异的结构基础，我们设计了一系列膜锚定的配体，其中EGF的核心受体结合域与EGF和HB-EGF的不同结构域结合在一起。我们发现，具有EGF N-末端延伸的配体即使从膜上释放，也不能与EGFR结合。缺少N端延伸但具有EGF膜锚定结构域的配体仍然需要蛋白水解性释放才能发挥活性，而具有HB-EGF膜锚定结构域的配体可以在仍然膜锚定的情况下激发出全部的生物学活性。含有HB-EGF膜锚但缺乏N-末端延伸的配体，在它们通过高尔基体的运输过程中激活了EGFR。然而，细胞混合实验和荧光共振能量转移研究表明，旁分泌信号通常以反式方式发生在细胞表面的细胞-细胞接触点。我们的数据表明，配体的膜锚定结构域选择性地控制它们参与旁分泌信号的能力，因此，只有一类EGFR配体可以在旁分泌模式下发挥作用。
All ligands of the epidermal growth factor (EGF) receptor (EGFR) are synthesized as membrane-anchored precursors. Previous work has suggested that some ligands, such as EGF, must be proteolytically released to be active, whereas others, such as heparin-binding EGF-like growth factor (HB-EGF) can function while still anchored to the membrane (i.e., juxtacrine signaling). To explore the structural basis for these differences in ligand activity, we engineered a series of membrane-anchored ligands in which the core, receptor-binding domain of EGF was combined with different domains of both EGF and HB-EGF. We found that ligands having the N-terminal extension of EGF could not bind to the EGFR, even when released from the membrane. Ligands lacking an N-terminal extension, but possessing the membrane-anchoring domain of EGF, still required proteolytic release for activity, whereas ligands with the membrane-anchoring domain of HB-EGF could elicit full biological activity while still membrane anchored. Ligands containing the HB-EGF membrane anchor, but lacking an N-terminal extension, activated EGFR during their transit through the Golgi apparatus. However, cell-mixing experiments and fluorescence resonance energy transfer studies showed that juxtacrine signaling typically occurred in trans at the cell surface, at points of cell-cell contact. Our data suggest that the membrane-anchoring domain of ligands selectively controls their ability to participate in juxtacrine signaling and thus, only a subclass of EGFR ligands can act in a juxtacrine mode.