Suzuki Takahisa, Oochi Keita, Hakeda-Suzuki Satoko, Suzuki Takashi
School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.
Dev Growth Differ. 2018 Sep;60(7):442-453. doi: 10.1111/dgd.12545. Epub 2018 Jul 10.
Blindness caused by the disconnection between photoreceptor cells and the brain can be cured by restoring this connection through the transplantation of retinal precursor neurons. However, even after transplanting these cells, it is still unclear how to guide the axons over the long distance from the retina to the brain. To establish a method of guiding the axons of transplanted neurons, we used the Drosophila visual system. By testing different conditions, including the dissociation and preincubation length, we have successfully established a method to transplant photoreceptor precursor cells isolated from the developing eye discs of third-instar larvae into the adult retina. Moreover, we overexpressed N-cadherin (CadN) in the transplant, since it is known to be broadly expressed in the optic lobe well after developmental stages, continuing through adult stages. We found that promoting the cell adhesive properties using CadN enhances the axonal length of the grafted photoreceptor neurons and therefore is useful for future transplantation. We tested the overexpression of a CadN::Frazzled chimeric receptor and found that there was no difference in axonal length from our wild-type transplants, suggesting that the intracellular domain of CadN is necessary for axonal elongation. Altogether, using the Drosophila visual system, we have established an excellent platform for exploring the molecules required for proper axon extension of transplanted neuronal cells. Future studies building from this platform will be useful for regenerative therapy of the human nervous system based on transplantation.
由光感受器细胞与大脑之间的连接中断所导致的失明，可通过移植视网膜前体神经元来恢复这种连接从而治愈。然而，即便移植了这些细胞，如何引导轴突从视网膜向大脑进行长距离生长仍不清楚。为了建立一种引导移植神经元轴突的方法，我们利用了果蝇视觉系统。通过测试不同条件，包括解离和预孵育时长，我们成功建立了一种将从三龄幼虫发育中的眼盘中分离出的光感受器前体细胞移植到成年果蝇视网膜中的方法。此外，我们在移植细胞中过表达了N - 钙黏蛋白（CadN），因为已知它在发育阶段之后直至成年阶段都在视叶中广泛表达。我们发现利用CadN增强细胞黏附特性可增加移植的光感受器神经元的轴突长度，因此对未来的移植有用。我们测试了CadN::Frazzled嵌合受体的过表达情况，发现其轴突长度与野生型移植并无差异，这表明CadN的细胞内结构域对轴突延长是必需的。总之，利用果蝇视觉系统，我们建立了一个出色的平台，用于探索移植神经元细胞正确轴突延伸所需的分子。基于这个平台开展的未来研究将有助于基于移植的人类神经系统再生治疗。
