The molecular control of glial progenitor proliferation in Drosophila and mammals

破坏性神经系统损伤（例如脊髓损伤、脑损伤）、老化脑的神经变性疾病（例如阿尔茨海默病）和脱髓鞘疾病（例如多发性硬化症）无法治愈，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胶质祖细胞移植到损伤部位。例如，将干细胞或神经胶质祖细胞移植到截瘫小鼠体内，可以修复断裂的轴突，恢复正常的运动。然而，目前缺乏对移植细胞如何表现的知识，这阻止了修复的保证，并阻止了对不期望的结果如癌症（即神经胶质瘤）的控制。因此，神经干细胞和神经胶质祖细胞增殖的分子理解是迫切需要的。在成年人CNS中存在神经胶质祖细胞，其在损伤或疾病时以所谓的神经胶质修复反应（GRR）分裂，导致自发的短暂恢复。虽然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为发现控制胶质祖细胞分裂和CNS修复的基因网络提供了一个千载难逢的机会。研究人类发育和疾病的重要基因网络经常使用果蝇，因为大多数基因网络在进化上是保守的。果蝇研究使强大的遗传学方法能够研究基因功能，它具有高细胞分辨率，技术复杂，廉价，快速，可以在整个和活动物中进行，并且不会引起伦理问题。我们已经在果蝇中发现了GRR，并且我们有一个详细的潜在分子遗传机制的工作模型：一个涉及Notch，Prospero/Prox 1，Eiger/ TNF和Dorsal/NFkB基因之间紧密关系的基因网络。本研究的目的是阐明果蝇和哺乳动物中枢神经系统中神经胶质祖细胞分裂和GRR调控的分子遗传机制。为了实现这一目标，我们的实验目标如下：（1）验证我们的工作模型，即候选基因参与果蝇静止神经胶质前体细胞增殖的控制。(2)将我们的发现转化为哺乳动物中枢神经系统，通过测试的神经胶质祖细胞和小鼠脊髓的GRR的背景下的哺乳动物同源物的功能。(3)使用果蝇测试和鉴定参与GRR和胶质细胞增殖的进一步基因，然后可以外推到哺乳动物胶质细胞增殖和GRR。该项目是果蝇和哺乳动物专家之间的合作，利用果蝇强大的遗传学来推进哺乳动物神经胶质祖细胞的研究。对受损或患病CNS的修复的研究通常依赖于哺乳动物模型，需要对动物造成严重的损伤，从在不同发育阶段的牺牲到造成物理损伤（例如，破坏脊髓）。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家的积极参与，以促进有效地转化为哺乳动物基因发现。在这里，我们将使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使用小鼠。我们的果蝇范例是简单的，并将成为更广泛的研究社区进一步研究GRR和药物测试的治疗目的，使用果蝇。这一建议响应了“3R：用无脊椎动物模型取代受保护动物”和“老龄化和终身福祉”研究的战略优先事项的呼吁。

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.