Gomez T M, Robles E, Poo M, Spitzer N C
Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093, USA.
Science. 2001 Mar 9;291(5510):1983-7. doi: 10.1126/science.1056490.
Filopodia that extend from neuronal growth cones sample the environment for extracellular guidance cues, but the signals they transmit to growth cones are unknown. Filopodia were observed generating localized transient elevations of intracellular calcium ([Ca2+]i) that propagate back to the growth cone and stimulate global Ca2+ elevations. The frequency of filopodial Ca2+ transients was substrate-dependent and may be due in part to influx of Ca2+ through channels activated by integrin receptors. These transients slowed neurite outgrowth by reducing filopodial motility and promoted turning when stimulated differentially within filopodia on one side of the growth cone. These rapid signals appear to serve both as autonomous regulators of filopodial movement and as frequency-coded signals integrated within the growth cone and could be a common signaling process for many motile cells.
从神经元生长锥伸出的丝状伪足会对细胞外引导信号进行环境采样，但其传递给生长锥的信号尚不清楚。研究人员观察到丝状伪足会产生局部的细胞内钙（[Ca2+]i）瞬时升高，这种升高会传播回生长锥并刺激整体Ca2+升高。丝状伪足Ca2+瞬变的频率取决于底物，部分原因可能是Ca2+通过整合素受体激活的通道流入。这些瞬变通过降低丝状伪足的运动性减缓了神经突的生长，并在生长锥一侧的丝状伪足内受到不同刺激时促进了转向。这些快速信号似乎既作为丝状伪足运动的自主调节因子，又作为整合在生长锥内的频率编码信号，可能是许多运动细胞的常见信号传导过程。
