Understanding Spinal Cord Regeneration; the role of dynamic gene expression

胚胎阶段的动物能够在破坏性损伤后重建功能组织。再生医学领域的广泛研究旨在了解胚胎发生和再生计划之间的相似之处，尽管在过去几十年中取得了很大进展，但其生物学和分子机制的许多方面仍不清楚。包括人类在内的哺乳动物不能在脊髓损伤(SCI)后修复丢失的神经元，而斑马鱼可以再生神经元来取代损伤后丢失的神经元。在损伤后，神经干细胞在具有再生能力的物种中启动增殖并产生新的神经元，但在哺乳动物中，只产生有助于疤痕形成的细胞。我自己的研究表明，在新神经元的生成(神经发生)的发育过程中，基因并不是简单地开启或关闭。相反，在特定因素的影响下，某些基因的水平会随着时间的推移而动态波动，并控制细胞是决定保持增殖的神经干细胞还是成为新的神经元。众所周知，同样的基因在脊髓再生(SCR)过程中也很重要，但它们是如何发挥作用的尚不清楚。因此，目前尚不清楚在SCR过程中新神经元的生成是否也受基因活动的脉冲控制。阐明在具有再生能力的动物中导致SCR成功的动态信号和机制将产生重要和有价值的结果，这些结果可以在高等生物体中进行测试。斑马鱼是一种强大、易驯服、健壮的动物模型，能够实现脊髓损伤后的功能性神经再生，其特点是新生神经发生和神经元连接的再生。在这项提案中，我将使用斑马鱼幼体作为实验模型，利用其再生能力和对基因操作的适应性。我将使用最先进的实时成像技术来显示基因活动。我将介绍基因变化，以评估当神经干细胞在SCR期间做出神经元决定时，脉动性基因活性的功能重要性。我将研究脉动基因活性的变化如何影响遗传格局，并在SCR期间随着时间的推移改变细胞命运决定。解决在SCR中决定细胞命运的脉动基因活性的功能重要性，将为没有再生能力的动物(如小鼠和人类)的SCI提供潜在的翻译含义。

Animals at embryonic stages are capable of reconstructing functional tissue after disruptive injuries. Extensive research in the field of regenerative medicine aims to understand the similarities between embryogenesis and regeneration programs and despite great advances in the last few decades, many aspects of the biological and molecular mechanisms remain unknown. Mammals, including humans, cannot replace lost neurons after spinal cord injury (SCI), whereas zebrafish can regenerate neurons to replace those that are lost after injury. Upon injury, neural stem cells initiate proliferation and generate new neurons in species with regenerative capacity, but in mammals, only cells that contribute to scar formation are generated. My own research has shown that during development the generation of new neurons (neurogenesis), genes are not simply on or off. Instead, the levels of some genes pulse dynamically over time, influenced by specific factors, and control whether the cells decide to stay as proliferating neural stem cell or become new neurons. It is known that the same genes are important during spinal cord regeneration (SCR) but how they work isn't known. Therefore, it is not clear whether during SCR and the generation of new neurons are also controlled by the pulses in gene activity. Elucidating the dynamic signals and mechanisms leading to successful SCR in an animal with regenerative capacity will generate important and valuable outcomes that can be tested in higher organisms. Zebrafish is a powerful, tractable and robust animal model able to achieve functional neural regeneration following SCI, characterised by de novo neurogenesis and regrowth of neuronal connections. In this proposal I will be using larvae zebrafish as an experimental model, taking advantage of its regenerative capacity and its amenability to genetic manipulation. I will use state-of-the art live imaging techniques that show gene activity in real time. I will introduce genetic changes to assess the functional importance of pulsatile gene activity when neural stem cells undertake neuronal decisions during SCR. I will investigate how changes on pulsatile gene activity can affect the genetic landscape and alter cell-fate decisions over time during SCR. Addressing the functional importance of pulsatile gene activity during cell-fate decisions in SCR, will provide insights with potential translational implications for SCI in animals with no regenerative capacity, such as mice and humans.