Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536, USA.
Biochemistry. 2010 May 18;49(19):4068-75. doi: 10.1021/bi100327r.
Neuropilin is an essential cell surface receptor that functions in both semaphorin-dependent axon guidance and vascular endothelial growth factor (VEGF)-dependent angiogenesis. The interplay between these two seemingly distinct pathways is a source of considerable interest. Indeed, several semaphorin family members have been shown to have potent anti-angiogenic activity in vivo. However, reports about whether semaphorin and VEGF competitively bind to neuropilin conflict. Previous work has demonstrated that all known ligands and inhibitors of neuropilin interact with the b1 domain of neuropilin via a C-terminal arginine. No semaphorin family member possesses a C-terminal arginine, leading to uncertainty with regard to the physical mechanism of interaction between the C-terminal domain of semaphorin and the b1 domain of neuropilin. Semaphorin 3F (Sema3F) possesses an RXRR furin recognition site in its C-terminus, and we demonstrate that it is proteolytically processed. This processing is found to be essential for the interaction of the C-terminus of Sema3F with the b1 domain of neuropilin. We further demonstrate that furin activation of the C-terminus of Sema3F produces a species that potently inhibits the binding of VEGF to neuropilin. These studies provide a mechanistic basis for understanding the anti-angiogenic activity of semaphorin as well as the physical interaction and competition between neuropilin ligands.
神经纤毛蛋白是一种重要的细胞表面受体，在信号蛋白依赖性轴突导向和血管内皮生长因子（VEGF）依赖性血管生成中发挥作用。这两个看似截然不同的途径之间的相互作用是一个非常有趣的研究领域。事实上，已经有几种信号蛋白家族成员被证明在体内具有很强的抗血管生成活性。然而，关于信号蛋白和 VEGF 是否竞争性结合神经纤毛蛋白的报告存在争议。以前的工作表明，神经纤毛蛋白的所有已知配体和抑制剂都通过 C 端精氨酸与神经纤毛蛋白的 b1 结构域相互作用。没有信号蛋白家族成员具有 C 端精氨酸，这导致了信号蛋白 C 端结构域与神经纤毛蛋白 b1 结构域之间相互作用的物理机制存在不确定性。信号蛋白 3F（Sema3F）在其 C 末端具有一个 RXRR 弗林识别位点，我们证明它是可被蛋白水解处理的。这种处理对于 Sema3F 的 C 末端与神经纤毛蛋白 b1 结构域的相互作用是必不可少的。我们进一步证明，弗林蛋白酶激活 Sema3F 的 C 末端会产生一种能够强烈抑制 VEGF 与神经纤毛蛋白结合的物质。这些研究为理解信号蛋白的抗血管生成活性以及神经纤毛蛋白配体之间的物理相互作用和竞争提供了机制基础。
