The molecular control of glial progenitor proliferation in Drosophila and mammals

毁灭性的神经系统损伤(如脊髓损伤、脑损伤)、老化大脑的神经退行性疾病(如阿尔茨海默病)和脱髓鞘疾病(如多发性硬化症)是无法治愈的，未来的治疗需要了解潜在的生物学。修复中枢神经系统(CNS)损伤和疾病的关键治疗方法是将干细胞或神经胶质前体细胞移植到损伤部位。例如，将干细胞或神经胶质前体细胞移植到截瘫小鼠身上，可以修复断裂的轴突，恢复正常的运动。然而，目前对移植细胞行为的缺乏了解阻碍了修复的保证，并阻止了对癌症(即胶质瘤)等不良结果的控制。因此，迫切需要从分子水平上了解神经干细胞和神经胶质前体细胞的增殖。在成年人的中枢神经系统中有神经胶质前体细胞，一旦受伤或疾病，就会分裂为神经胶质修复反应(GRR)，导致自发的短暂恢复。尽管GRR不会导致功能修复，但它揭示了神经系统自我修复的内在趋势。如果我们知道潜在的基因是什么，以及它们是如何工作的，我们就可以操纵它们来诱导修复。GRR为发现控制神经胶质前体细胞分裂和中枢神经系统修复的基因网络提供了黄金机会。研究出对人类发育和疾病很重要的基因网络通常是用果蝇完成的，因为大多数基因网络在进化上是保守的。果蝇的研究为研究基因功能提供了强大的遗传学方法，它具有高细胞分辨率，技术复杂，廉价，快速，可以在整体和活动物身上完成，而且不会引起伦理问题。我们已经在果蝇中发现了GRR，并对其潜在的分子遗传机制有了一个详细的工作模型：一个基因网络，涉及Notch、Propero/Prox1、Eiger/TNF和dorsal/NFkB基因之间的紧密关系。本研究的目的是研究果蝇和哺乳动物中枢神经系统中神经胶质前体细胞分裂和GRR调控的分子遗传学机制。为了实现这一目标，将致力于以下实验目标：(1)测试我们的工作模型，即候选基因参与控制果蝇静止的神经胶质前体细胞的增殖。(2)通过在神经胶质祖细胞和小鼠脊髓GRR的背景下测试哺乳动物同源物的功能，将我们的发现转化到哺乳动物的中枢神经系统。(3)利用果蝇进一步检测和鉴定与GRR和胶质细胞增殖相关的基因，从而推测哺乳动物神经胶质细胞的增殖和GRR。这个项目是一名果蝇和一名哺乳动物专家的合作，目的是利用果蝇强大的遗传学来推进哺乳动物神经胶质前体的研究。对受损或患病中枢神经系统修复的研究通常依赖于哺乳动物动物模型，需要对动物造成从不同发育阶段的牺牲到造成物理损害(例如脊髓断裂)的严重损害。虽然果蝇研究不会引起伦理问题，但使用果蝇的基础研究需要果蝇学者的积极参与，以促进有效地转化为哺乳动物的基因发现。在这里，我们将用果蝇来推动哺乳动物的研究，同时以这种方式取代和减少老鼠的使用。我们的果蝇范例很简单，将提供给更广泛的研究社区，用于进一步研究GRR和使用果蝇进行治疗药物测试。这项提议响应了“3R：用无脊椎动物模型取代受保护动物”的号召，以及“老龄化和终身健康”研究的战略重点。

Devastating nervous system injury (e.g. spinal cord injury, brain damage), neurodegenerative diseases of the ageing brain (e.g. Alzheimer's disease) and demyelinating diseases (e.g. multiple sclerosis) cannot be cured and future therapy requires understanding of the underlying biology. The key therapeutic approach to repair central nervous system (CNS) damage and disease is the transplantation of stem cells or glial progenitors to the site of injury. For instance, transplantation of stem cells or glial progenitor cells in paraplegic mice repairs the broken axons and restores normal movement. However, the current lack of knowledge of how the transplanted cells behave prevents a guarantee of repair, and prevents control over undesirable outcomes such as cancer (i.e. gliomas). Thus a molecular understanding of neural stem cell and glial progenitor proliferation is urgently required. There are glial progenitors in the adult human CNS, which upon injury or disease divide in what is known as the glial-repair response (GRR), leading to a spontaneous brief recovery. Although the GRR does not result in functional repair, it reveals an intrinsic tendency of the nervous system to repair itself. If we knew what the underlying genes are and how they work, we could manipulate them to induce repair. A golden opportunity to discovering the gene network controlling glial progenitor cell division and CNS repair is provided by the GRR. Working out gene networks important for human development and disease is frequently done using the fruit-fly Drosophila because most gene networks are evolutionarily conserved. Drosophila research enables powerful genetic approaches to investigating gene function, it has high cellular resolution, it is technically sophisticated, cheap, quick, it can be done in whole and in living animals, and it does not raise ethical concerns. We have discovered a GRR in Drosophila and we have a detailed working model of the underlying molecular genetic mechanism: a gene network involving a tight relationship between the genes Notch, Prospero/Prox1, Eiger/ TNF and Dorsal/NFkB. The aim of this proposal is to work out the molecular genetic mechanism underlying the control of glial progenitor division and the GRR in the Drosophila and mammalian CNSs. To meet this aim, the following experimental objectives will be addressed: (1) To test our working model on the involvement of the candidate genes in the control of proliferation of quiescent glial precursors in Drosophila. (2) To translate our findings to the mammalian CNS, by testing the functions of the mammalian homologues in the context of glial progenitors and the GRR of the mouse spinal cord. (3) To use Drosophila to test and identify further genes involved in the GRR and glial proliferation, which can then be extrapolated to mammalian glial proliferation and GRR. This project is a collaboration between a Drosophila and a mammalian expert to use the powerful genetics of Drosophila to advance mammalian glial progenitor research. Research into repair of the damaged or diseased CNS typically relies on mammalian animal models, requiring a severity of damage to animals ranging from sacrifice at different stages of development to inflicting physical damage (e.g. breaking the spinal cord). While Drosophila research does not raise ethical concerns, basic research using fruit-flies requires an active involvement of Drosophilists to promote the effective translation to mammalian gene discovery. Here, we will use Drosophila to propel mammalian research while in this way replacing and reducing the use of mice. Our Drosophila paradigm is simple and will become available to the wider research community for further research into the GRR and drug testing for therapeutic purposes using fruit-flies. This proposal responds to the call for the '3Rs: replacing protected animals with invertebrate models' and the strategic priority of 'Ageing and lifelong wellbeing' research.