Liu Yan, Berndt Jason, Su Fengyun, Tawarayama Hiroshi, Shoji Wataru, Kuwada John Y, Halloran Mary C
Department of Zoology and Anatomy, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Neurosci. 2004 Jan 14;24(2):310-8. doi: 10.1523/JNEUROSCI.4287-03.2004.
We examined the role of Sema3D, a semaphorin of previously unknown function, in guiding retinal ganglion cell (RGC) axons to the optic tectum in the developing zebrafish. Sema3D is expressed more strongly in the ventral versus dorsal tectum, suggesting that it may participate in guiding RGC axons along the dorsoventral axis of the tectum. Ubiquitous misexpression of Sema3D in transgenic zebrafish inhibits ventral but not dorsal RGC axon growth. In addition, ventral RGC axons avoid or stop at individual cells misexpressing Sema3D along their pathway. Sema3D ubiquitous misexpression at later stages also causes ventral RGC axon arbors to spread more widely along the dorsoventral axis of the tectum. Knock-down of Sema3D with morpholino antisense causes ventral RGC axons to extend aberrantly into the ventral tectum. These results suggest that Sema3D in the ventral tectum normally acts to inhibit ventral RGCs from extending into ventral tectum, ensuring their correct innervation of dorsal tectum.
我们研究了信号素3D（Sema3D）在引导发育中的斑马鱼视网膜神经节细胞（RGC）轴突至视顶盖过程中的作用，Sema3D是一种功能此前未知的信号素。Sema3D在视顶盖腹侧的表达强于背侧，这表明它可能参与引导RGC轴突沿视顶盖的背腹轴生长。在转基因斑马鱼中普遍过表达Sema3D会抑制腹侧而非背侧RGC轴突的生长。此外，腹侧RGC轴突会避开沿其路径过表达Sema3D的单个细胞或在这些细胞处停止生长。在后期普遍过表达Sema3D还会导致腹侧RGC轴突分支沿视顶盖的背腹轴更广泛地扩散。用吗啉代反义寡核苷酸敲低Sema3D会导致腹侧RGC轴突异常延伸至腹侧视顶盖。这些结果表明，腹侧视顶盖中的Sema3D通常起到抑制腹侧RGC轴突延伸至腹侧视顶盖的作用，确保它们正确地支配背侧视顶盖。
