Hernández-Núñez Ismael, Robledo Diego, Mayeur Hélène, Mazan Sylvie, Sánchez Laura, Adrio Fátima, Barreiro-Iglesias Antón, Candal Eva
Departamento de Bioloxía Funcional, Facultade de Bioloxía, CIBUS, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.
Front Cell Dev Biol. 2021 Feb 11;9:628721. doi: 10.3389/fcell.2021.628721. eCollection 2021.
Neurogenesis is the process by which progenitor cells generate new neurons. As development progresses neurogenesis becomes restricted to discrete neurogenic niches, where it persists during postnatal life. The retina of teleost fishes is thought to proliferate and produce new cells throughout life. Whether this capacity may be an ancestral characteristic of gnathostome vertebrates is completely unknown. Cartilaginous fishes occupy a key phylogenetic position to infer ancestral states fixed prior to the gnathostome radiation. Previous work from our group revealed that the juvenile retina of the catshark , a cartilaginous fish, shows active proliferation and neurogenesis. Here, we compared the morphology and proliferative status of the retina in catshark juveniles and adults. Histological and immunohistochemical analyses revealed an important reduction in the size of the peripheral retina (where progenitor cells are mainly located), a decrease in the thickness of the inner nuclear layer (INL), an increase in the thickness of the inner plexiform layer and a decrease in the cell density in the INL and in the ganglion cell layer in adults. Contrary to what has been reported in teleost fish, mitotic activity in the catshark retina was virtually absent after sexual maturation. Based on these results, we carried out RNA-Sequencing (RNA-Seq) analyses comparing the retinal transcriptome of juveniles and adults, which revealed a statistically significant decrease in the expression of many genes involved in cell proliferation and neurogenesis in adult catsharks. Our RNA-Seq data provides an excellent resource to identify new signaling pathways controlling neurogenesis in the vertebrate retina.
神经发生是祖细胞产生新神经元的过程。随着发育的进行，神经发生局限于离散的神经源性微环境，在出生后的生命过程中持续存在。硬骨鱼类的视网膜被认为在整个生命过程中都会增殖并产生新细胞。这种能力是否可能是有颌脊椎动物的祖先特征，目前完全未知。软骨鱼类在推断有颌类辐射之前固定的祖先状态方面占据关键的系统发育位置。我们小组之前的研究表明，软骨鱼猫鲨的幼体视网膜显示出活跃的增殖和神经发生。在这里，我们比较了猫鲨幼体和成体视网膜的形态和增殖状态。组织学和免疫组织化学分析显示，成年猫鲨外周视网膜（祖细胞主要位于此处）的大小显著减小，内核层（INL）厚度降低，内网状层厚度增加，INL和神经节细胞层的细胞密度降低。与硬骨鱼类的报道相反，猫鲨视网膜在性成熟后几乎没有有丝分裂活性。基于这些结果，我们进行了RNA测序（RNA-Seq）分析，比较了幼体和成体的视网膜转录组，结果显示成年猫鲨中许多参与细胞增殖和神经发生的基因表达在统计学上显著下降。我们的RNA-Seq数据为鉴定控制脊椎动物视网膜神经发生的新信号通路提供了极好的资源。
