Medori Mara, Spelzini Gonzalo, Scicolone Gabriel
CONICET - Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis" (IBCN); Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina.
Neural Regen Res. 2020 Mar;15(3):382-389. doi: 10.4103/1673-5374.266044.
Investigating the cellular and molecular mechanisms involved in the development of topographically ordered connections in the central nervous system constitutes an important issue in neurobiology because these connections are the base of the central nervous system normal function. The dominant model to study the development of topographic maps is the projection from the retinal ganglion cells to the optic tectum/colliculus. The expression pattern of Eph/ephrin system in opposing gradients both in the retina and the tectum, labels the local addresses on the target and gives specific sensitivities to growth cones according to their topographic origin in the retina. The rigid precision of normal retinotopic mapping has prompted the chemoaffinity hypothesis, positing axonal targeting to be based on fixed biochemical affinities between fibers and targets. However, several lines of evidence have shown that the mapping can adjust to experimentally modified targets with flexibility, demonstrating the robustness of the guidance process. Here we discuss the complex ways the Ephs and ephrins interact allowing to understand how the retinotectal mapping is a precise but also a flexible process.
研究中枢神经系统中拓扑有序连接发育所涉及的细胞和分子机制是神经生物学中的一个重要问题，因为这些连接是中枢神经系统正常功能的基础。研究拓扑图谱发育的主要模型是视网膜神经节细胞向视顶盖/视丘的投射。视网膜和视顶盖中Eph/ephrin系统以相反梯度的表达模式，标记了靶标上的局部位置，并根据生长锥在视网膜中的拓扑起源赋予其特定的敏感性。正常视网膜拓扑映射的严格精确性促使了化学亲和性假说的提出，该假说认为轴突靶向基于纤维与靶标之间固定的生化亲和性。然而，多条证据表明，这种映射能够灵活地适应实验性改变的靶标，证明了导向过程的稳健性。在这里，我们讨论Ephs和ephrins相互作用的复杂方式，以便理解视网膜-视顶盖映射是一个精确但又灵活的过程。
