Institute of Anatomy and Molecular Embryology, Faculty of Medicine, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany.
Histochem Cell Biol. 2013 Mar;139(3):431-45. doi: 10.1007/s00418-012-1036-y. Epub 2012 Oct 4.
The neuronal growth cone plays a crucial role in the development of the nervous system. This highly motile structure leads the axon to its final destination by translating guidance cues into cytoskeletal rearrangements. Recently, vascular endothelial growth factor (VEGF), which is essential for angiogenesis and vascular sprouting, has been found to exert a trophic activity also on neurons, leading to an increased axonal outgrowth, similar to the well-known nerve growth factor (NGF). The neurotrophic properties of VEGF are likely to be promoted via the VEGF receptor 2 (VEGFR-2) and neuropilin-1 (NRP-1). In the long term, VEGF attracts and influences the growth cone velocity and leads to growth cone enlargement. The present study focuses on immediate VEGF effects using RFP-actin and GFP-NF-M microinjected chicken dorsal root ganglia for live cell imaging of the neuronal growth cone. We analyzed actin and neurofilament dynamics following VEGF and NGF treatment and compared the effects. Furthermore, key signaling pathways of VEGF were investigated by specific blocking of VEGFR-2 or NRP-1. With the aid of confocal laser scanning microscopy and stimulated emission depletion microscopy, we show for the first time that VEGF has a quick effect on the actin-cytoskeleton, since actin rearrangements were identifiable within a few minutes, leading to a dramatically increased motion. Moreover, these effects were strongly enhanced by adding both VEGF and NGF. Most notably, the effects were inhibited by blocking VEGFR-2, therefore we propose that the immediate effects of VEGF on the actin-cytoskeleton are mediated through VEGFR-2.
神经元生长锥在神经系统的发育中起着至关重要的作用。这个高度活跃的结构通过将导向线索转化为细胞骨架重排，引导轴突到达最终目的地。最近，血管内皮生长因子（VEGF），对于血管生成和血管发芽是必不可少的，也被发现对神经元具有营养活性，导致轴突生长增加，类似于众所周知的神经生长因子（NGF）。VEGF 的神经营养特性可能是通过 VEGF 受体 2（VEGFR-2）和神经纤毛蛋白-1（NRP-1）促进的。从长远来看，VEGF 吸引并影响生长锥的速度，并导致生长锥扩大。本研究使用红色荧光蛋白-肌动蛋白（RFP-actin）和 GFP-NF-M 微注射鸡背根神经节，对神经元生长锥进行活细胞成像，重点研究 VEGF 的即时效应。我们分析了 VEGF 和 NGF 处理后肌动蛋白和神经丝的动力学，并比较了它们的影响。此外，还通过特异性阻断 VEGFR-2 或 NRP-1 来研究 VEGF 的关键信号通路。借助共聚焦激光扫描显微镜和受激发射损耗显微镜，我们首次表明 VEGF 对肌动蛋白细胞骨架有快速作用，因为在几分钟内就可以识别出肌动蛋白重排，从而导致运动显著增加。此外，添加 VEGF 和 NGF 会大大增强这些效果。值得注意的是，阻断 VEGFR-2 可抑制这些效果，因此我们提出 VEGF 对肌动蛋白细胞骨架的即时作用是通过 VEGFR-2 介导的。
