Complementary expression of transmembrane ephrins and their receptors in the mouse spinal cord: a possible role in constraining the orientation of longitudinally projecting axons.
Complementary expression of transmembrane ephrins and their receptors in the mouse spinal cord: a possible role in constraining the orientation of longitudinally projecting axons.
复制标题
小鼠脊髓中跨膜肝配蛋白及其受体的互补表达：在限制纵向突出轴突的方向方面可能发挥作用。
作者：
R. Imondi;Christi Wideman;Z. Kaprielian
在发育中的脊髓中，轴突在垂直于底板的横向平面和平行于底板的纵向平面上突出。对于许多轴突来说，底板是长程和短程引导信号的来源，控制着两个维度的生长。我们在此表明，B 类跨膜肝配蛋白及其受体在小鼠脊髓的底板细胞和纵向突出的轴突上相互表达。在连合轴突寻路期间，B 类肝配蛋白在侧底板边界、底板和腹侧索之间的界面处表达。相反，B类Eph受体在腹侧索内突出的交错连合轴突节段和构成侧索的同侧突出轴突上表达。所有三种 B 类肝配蛋白的可溶形式在体外均与连合生长锥结合并诱导其塌陷。与 B 类肝配蛋白相关的崩溃诱导活性可能是由 EphB1 介导的。总而言之，这些数据支持排斥性 B 类 Eph 受体/配体相互作用在限制腹侧中线纵向轴突投影的方向方面可能发挥的作用。
In the developing spinal cord, axons project in both the transverse plane, perpendicular to the floor plate, and in the longitudinal plane, parallel to the floor plate. For many axons, the floor plate is a source of long- and short-range guidance cues that govern growth along both dimensions. We show here that B-class transmembrane ephrins and their receptors are reciprocally expressed on floor plate cells and longitudinally projecting axons in the mouse spinal cord. During the period of commissural axon pathfinding, B-class ephrin protein is expressed at the lateral floor plate boundaries, at the interface between the floor plate and the ventral funiculus. In contrast, B-class Eph receptors are expressed on decussated commissural axon segments projecting within the ventral funiculus, and on ipsilaterally projecting axons constituting the lateral funiculus. Soluble forms of all three B-class ephrins bind to, and induce the collapse of, commissural growth cones in vitro. The collapse-inducing activity associated with B-class ephrins is likely to be mediated by EphB1. Taken together, these data support a possible role for repulsive B-class Eph receptor/ligand interactions in constraining the orientation of longitudinal axon projections at the ventral midline.