Payne H R, Burden S M, Lemmon V
Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106-4975.
Cell Motil Cytoskeleton. 1992;21(1):65-73. doi: 10.1002/cm.970210108.
The growth cone, a terminal structure on developing and regenerating axons, is specialized for motility and guidance functions. In vivo the growth cone responds to environmental cues to guide the axon to its appropriate target. These cues are thought to be responsible for position-specific morphological changes in the growth cone, but the molecules that control growth cone behavior are poorly characterized. We used scanning electron microscopy to analyze the morphology of retinal ganglion cell growth cones in vitro on different adhesion molecules that axons normally encounter in vivo. L1/8D9, N-cadherin, and laminin each induced distinctive morphological characteristics in growth cones. Growth cones elaborated lamellipodial structures in response to the cell adhesion molecules L1/8D9 and N-cadherin, whereas laminin supported filopodial growth cones with small veils. On L1/8D9, the growth cones were larger and produced more filopodia. Filopodial associations between adjacent growth cones and neurites were frequent on L1/8D9 but were uncommon on laminin or N-cadherin. These results demonstrate that different adhesion molecules have profoundly different effects on growth cone morphology. This is consistent with previous reports suggesting that changes in growth cone morphology in vivo occur in response to changes in substrate composition.
生长锥是发育中和再生轴突上的一种终末结构，专门用于运动和导向功能。在体内，生长锥对环境线索作出反应，引导轴突到达其合适的靶点。这些线索被认为是导致生长锥出现位置特异性形态变化的原因，但控制生长锥行为的分子却鲜为人知。我们利用扫描电子显微镜分析了体外培养的视网膜神经节细胞生长锥在轴突在体内通常会遇到的不同黏附分子上的形态。L1/8D9、N-钙黏蛋白和层粘连蛋白各自在生长锥中诱导出独特的形态特征。生长锥对细胞黏附分子L1/8D9和N-钙黏蛋白作出反应，形成片状伪足结构，而层粘连蛋白则支持带有小膜的丝状伪足生长锥。在L1/8D9上，生长锥更大，产生的丝状伪足更多。相邻生长锥和神经突之间的丝状伪足连接在L1/8D9上很常见，但在层粘连蛋白或N-钙黏蛋白上则不常见。这些结果表明，不同的黏附分子对生长锥形态有截然不同的影响。这与之前的报道一致，即体内生长锥形态的变化是对底物成分变化的反应。
