Bagnard D, Thomasset N, Lohrum M, Püschel A W, Bolz J
Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 371, Cerveau et Vision, 69500 Bron, France.
J Neurosci. 2000 Feb 1;20(3):1030-5. doi: 10.1523/JNEUROSCI.20-03-01030.2000.
It is generally assumed that gradients of chemotropic molecules are instrumental to the wiring of the nervous system. Recently, two members of the secreted class III semaphorin protein family have been implicated as repulsive (Sema3A) and attractive (Sema3C) guidance molecules for cortical axons (). Here, we show that stabilized gradients of increasing semaphorin concentrations elicit stereotyped responses from cortical growth cones, independent of the absolute concentration and the slope of these gradients. In contrast, neither repulsive effects of Sema3A nor attractive effects of Sema3C were observed when axons were growing toward decreasing semaphorin concentrations. Thus, growth cone guidance by gradients of chemotropic molecules is robust and reproducible, because it is primarily independent of the exact dimensions of the gradients.
一般认为，趋化分子梯度对神经系统的布线至关重要。最近，分泌型III类信号素蛋白家族的两个成员被认为是皮质轴突的排斥性（Sema3A）和吸引性（Sema3C）导向分子（）。在这里，我们表明，信号素浓度增加的稳定梯度会引发皮质生长锥的刻板反应，而与这些梯度的绝对浓度和斜率无关。相反，当轴突朝着信号素浓度降低的方向生长时，未观察到Sema3A的排斥作用或Sema3C的吸引作用。因此，趋化分子梯度对生长锥的导向作用是强大且可重复的，因为它主要独立于梯度的确切维度。
