Polarity and laminar formation of the optic tectum in relation to retinal projection
Polarity and laminar formation of the optic tectum in relation to retinal projection
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DOI：
10.1002/neu.10339
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发表时间：
2004-04-01
期刊：
影响因子：
--
通讯作者：
Sugiyama, S
中科院分区：
文献类型：
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作者：
Nakamura, H;Sugiyama, S
大脑中脑边界(峡部)作为顶盖的组织者，其组织分子可能是Fgf8。OTX2、EN1和Pax2重叠表达的区域可能分化为中脑。Pax6和En1/Pax2以及OTX2和Gbx2的相互抑制作用分别决定了中脑和中脑的边界。视顶盖是低等脊椎动物的视觉中心。顶盖和视网膜应该被区域化，并在适当的位置上进行专门化以获得正确的视网膜定位投影。EN2的梯度在顶盖肩尾极性的形成中起着至关重要的作用。EN2通过诱导视网膜颞叶神经节细胞生长锥体的排斥性分子eaffinA2和A5，赋予视网膜的尾部特征。Grg4拮抗峡部相关基因，参与发育早期双中脑边界的形成和顶盖极性的形成。然后，Grg4通过控制迁移途径在顶盖板层的形成中发挥作用。顶盖有丝分裂后细胞的迁移途径在E5后发生了变化。晚迁移细胞将早迁移神经元分裂成h-j板层。Grg4在E5后的脑室层表达，迫使有丝分裂后细胞沿着晚期迁移途径进行，尽管视网膜纤维终止于SGFS的a-f板层。Grg4的错误表达破坏了g层，在这样的顶盖中，视网膜树枝深入到顶盖层，表明g层是视网膜树枝的不允许层。(C)2004年威利期刊公司。
The mes-metencephalic boundary (isthmus) works as an organizer for the tectum, and the organizing molecule may be Fgf8. The region where Otx2, En1, and Pax2 are expressed overlappingly may differentiate into the mesencephalon. The di-mesencephalic and mes-metencephalic boundaries are determined by repressive interaction of Pax6 and En1/Pax2 and of Otx2 and Gbx2, respectively. The optic tectum is a visual center in lower vertebrates. The tectum and the retina should be regionalized and be positionally specialized for the proper retinotopic projection. Gradient of En2 plays a crucial role in rostrocaudal polarity formation of the tectum. En2 confers caudal characteristics of the retina by inducing ephrinA2 and A5, which are the repellant molecules for the growth cones of temporal retinal ganglion cells. Grg4 antagonizes the isthmus-related genes, and is involved in the formation of di-mesencephalic boundary and tectal polarity formation at an early phase of development. Then, Grg4 plays a role in tectal laminar formation by controlling the migration pathway. Migration pathway of tectal postmitotic cells changes after E5. The late migratory cells split the early migratory neurons to form laminae h-j of SGFS. Grg4 is expressed in the ventricular layer after E5, and forces postmitotic cells to follow the late migratory pathway, though retinal fibers terminate at laminae a-f of SGFS. Misexpression of Grg4 disrupts the lamina g, and in such tecta retinal arbors invade deep into the tectal layer, indicating that lamina g is a nonpermissive lamina for the retinal arbors. (C) 2004 Wiley Periodicals, Inc.