Regulation of neural stem cells by retinoic acid and Notch signalling in the regenerating axolotl spinal cord

再生有功能的脊髓的能力仅限于少数脊椎动物物种，其中最主要的是尾巴两栖动物，如蝾螈和火蜥蜴，以及一些硬骨鱼。在“有再生能力的”物种中，这种能力背后的复杂过程在很大程度上仍是未知的。我们建议使用墨西哥的Axolotl，一种成熟的具有再生能力的两栖动物，来研究脊髓再生是如何起作用的。在我们先前研究的基础上，我们计划研究在再生过程中协调细胞间相互作用的两条通讯通路：维甲酸(RA)和Notch通路。我们将通过使用转基因的axolotl幼虫来鉴定和可视化脊髓细胞的关键群体-室管膜神经胶质(EG)神经干细胞中RA信号的多个核受体活性的细胞位置。我们将采用新开发的光遗传学方法，使我们能够利用光来调节在正常脊髓再生过程中不同时间发生在EG细胞中的通讯事件。重要的是，我们的工作将是第一次在这个水平上研究一些细胞间通信网络在脊髓再生过程中是如何协调的。所有这些工作都将由硕士和博士生完成，他们将在脊髓研究的尖端方法方面接受宝贵的培训。通过我们的工作，我们将开发新的研究工具，这些工具将与加拿大和国外的脊髓研究社区共享。我们希望做出重要的新发现，开始解开导致这些物种再生能力的复杂信号通路，并可能阐明为什么哺乳动物在进化过程中失去了这种能力。

The ability to regenerate a functional spinal cord is restricted to only a few vertebrate species, foremost among them tailed amphibians such as newts and salamanders, and some bony fish. The complex processes that underlie this ability in “regeneration-competent” species is still largely unknown. We are proposing to use the Mexican axolotl, a well-established regeneration-competent amphibian, to examine how spinal cord regeneration works. Based on our previous research, we plan to examine two communication pathways that coordinate interactions between cells during regeneration: the retinoic acid (RA) and Notch pathways. We will do this by using genetically modified “transgenic” axolotl larvae to identify and visualize the cellular sites of activity of multiple nuclear receptors for RA signaling in a key population of spinal cord cells the ependymoglial (EG) neural stem cells. We will bring to bear newly developed optogenetic' methods that will enable us to use light to regulate the communication events that occur in EG cells at various times during normal spinal cord regeneration. Importantly, our work will be the first to examine, at this level, how some intercellular communication networks are coordinated during spinal cord regeneration. All of this work will be performed by MSc and PhD students, who will receive valuable training in cutting edge methods in spinal cord research. Through the course of our work we will develop new research tools that will be shared with the spinal cord research community in Canada and abroad. We hope to make important new discoveries that can begin to unravel the complex signaling pathways that lead to regeneration competence in these species and which could shed light on why mammals have lost this ability during evolution.