Muzio Luca, Mallamaci Antonello
Department of Biological and Technological Research (DIBIT), Istituto Scientifico H. San Raffaele, via Olgettina 58, 20132 Milano, Italy.
Cereb Cortex. 2003 Jun;13(6):641-7. doi: 10.1093/cercor/13.6.641.
Three basic aspects of cerebral cortex development - specification of cortical versus ganglionic identity, regionalization of the early cortical primordium and arealization of the developing cortex - were the main subject of our recent investigations. We previously demonstrated that the two homeobox genes Emx2 and Pax6 promote development of caudal-medial and rostral-lateral cortex, respectively, by properly shaping the early cortical protomap and possibly modulating the tangential growth ratio between medial and lateral cortical anlagen. More recently, by analyzing the brains of embryos bearing mutations for Emx2 and Pax6 in different combinations, we found that both genes are necessary and sufficient for a more basic developmental choice, i.e. the specification of neuroblasts in the dorsal telencephalon as cortical versus ganglionic neuroblasts. Finally, we explored the possible roles of the Emx2 paralog, Emx1, in these processes. By looking at embryos mutant for Emx1, Emx2 and Pax6 in various combinations, we did not get any evidence of Emx1 involvement in the process of cortical specification; conversely, this gene appeared to be involved to some extent in the process of regionalization of the cortical primordium along the medial-lateral axis, as a promoter of medial fates.
大脑皮层发育的三个基本方面——皮层与神经节身份的特化、早期皮层原基的区域化以及发育中皮层的分区化——是我们近期研究的主要主题。我们之前证明，两个同源框基因Emx2和Pax6分别通过恰当地塑造早期皮层原图谱并可能调节内侧和外侧皮层原基之间的切向生长比例，促进尾内侧和嘴外侧皮层的发育。最近，通过分析不同组合携带Emx2和Pax6突变的胚胎大脑，我们发现这两个基因对于一个更基本的发育选择是必要且充分的，即端脑背侧神经母细胞作为皮层神经母细胞与神经节神经母细胞的特化。最后，我们探究了Emx2旁系同源基因Emx1在这些过程中的可能作用。通过观察不同组合中Emx1、Emx2和Pax6突变的胚胎，我们没有得到Emx1参与皮层特化过程的任何证据；相反，作为内侧命运的促进因子，该基因似乎在一定程度上参与了皮层原基沿内侧-外侧轴的区域化过程。
