Luque Juan M
Instituto de Neurociencias, UMH-CSIC, San Juan de Alicante, Spain.
Brain Res. 2007 Apr 6;1140:41-50. doi: 10.1016/j.brainres.2006.02.056. Epub 2006 Mar 29.
Much has been learnt about the reeler mutant since its inclusion in the celebrated Catalog of the Neurological Mutants of the Mouse in the mid-sixties. The pace of discovery was most definitively agitated after the identification of reelin, the genuine gene product mutated in reeler (first expressed by a monolayer of cells in the marginal zone of the developing brain), and the subsequent establishment of the so-called reelin signaling pathway (including the reelin receptor machinery expressed by migrating newborn neurons). Yet little is known as to how the reelin signaling events, which are critically involved in neuronal migration, are linked to the in vivo behavior of individual neurons. Lately, the results of the forced ectopic expression of reelin in the neurogenic zone jeopardized all proposed models regarding its mechanism of action. Our studies suggest that earlier than newborn neurons, the radial glia neuronal progenitors may receive a functional reelin signal. Here I show evidence of an enriched localization of the reelin receptor machinery in radial glial cells of the lateral, but not the median, ganglionic eminence. This precise compartmentalization suggests that, unlike radial migration of cortical projection neurons, reelin signaling is not directly related with the tangential migration of the bulk of cortical interneurons. I hereby submit a personal glimpse of reeler morphogenesis which embodies a testable hypothesis; namely, that reelin signals to unique neural lineages to regulate migration.
自六十年代中期“小鼠神经突变体目录”将reeler突变体收录其中以来，人们对它已有了诸多了解。在鉴定出reelin（reeler中发生突变的真正基因产物，最初由发育中大脑边缘区的单层细胞表达）以及随后建立所谓的reelin信号通路（包括迁移的新生神经元表达的reelin受体机制）之后，发现的步伐明显加快。然而，对于在神经元迁移中起关键作用的reelin信号事件如何与单个神经元的体内行为相关联，人们却知之甚少。最近，在神经发生区强制异位表达reelin的结果危及了所有关于其作用机制的模型。我们的研究表明，早于新生神经元，放射状胶质神经元祖细胞可能会接收到功能性的reelin信号。在此，我展示了reelin受体机制在外侧神经节隆起而非内侧神经节隆起的放射状胶质细胞中富集定位的证据。这种精确的分区表明，与皮质投射神经元的放射状迁移不同，reelin信号与大多数皮质中间神经元的切向迁移没有直接关系。在此，我提出了对reeler形态发生的个人见解，其中包含一个可检验的假设，即reelin向独特的神经谱系发出信号以调节迁移。
