Investigating the mechanisms of axonal degeneration in amyotrophic lateral sclerosis using Drosophila and mouse transgenics

肌萎缩侧索硬化症是一种毁灭性的、进行性的、使人瘫痪的疾病，每年在英国导致1200多人死亡，通常在发病后3-5年内死亡。它通常影响50多岁及以上的人，但也可能影响任何年龄的成年人。尽管经过了几十年的研究，ALS仍然是无法治愈的，医疗护理基本上是姑息治疗(呼吸机和喂食管)。肌萎缩侧索硬化症的病因尚不完全清楚，但在大约10%的病例中，可能有肌萎缩侧索硬化症的家族病史表明是遗传原因。令人兴奋的是，在过去的五年里，随着许多与肌萎缩侧索硬化症相关的基因的发现，我们对肌萎缩侧索硬化症的理解出现了爆炸性增长。其中最重要的基因之一是TDP-43。最近的突破性研究发现，95%的肌萎缩侧索硬化症患者的大脑和脊髓中有TDP-43的成团。在一些患者中，产生TDP-43的基因也发生了突变，我们现在认为TDP-43在导致几乎所有ALS病例中起着重要作用。因此，研究人员认为，肌萎缩侧索硬化症的TDP-43模型将对找出肌萎缩侧索硬化症的根本原因至关重要，并最终开发出急需的治疗方法。科学家的另一个重要考虑是了解肌萎缩侧索硬化症是如何开始的，因为在早期阶段治疗肌萎缩侧索硬化症可能是最有效的治疗方法。肌萎缩侧索硬化症的特征是被称为运动神经元的神经细胞丢失。这些细胞有细长的突起，称为轴突，将它们与其他神经细胞和肌肉连接起来，使我们能够移动、吞咽和呼吸。在肌萎缩侧索硬化症中，最早的疾病迹象出现在这些轴突上。因此，我们相信，通过保护这些轴突，我们可以防止ALS的最早阶段。令人兴奋的是，已经发现了两种保护因素，当轴突被切断时，它们可以极大地保护轴突。然而，这些因素从未在ALS的TDP-43模型中进行过测试。我计划在转基因TDP-43果蝇和模拟肌萎缩侧索硬化症的小鼠身上测试这些因素。我还计划使用这些模型来寻找保护ALS轴突的新方法，这可能会开辟全新的研究途径。我将在发现这些保护因素的两位世界领先的轴突专家科尔曼博士和弗里曼博士的实验室进行这项研究。对于科学家来说，飞行是一个很好的模型，因为它们的基因与人类非常相似，包括TDP-43，并且有相似类型的运动神经元、肌肉和大脑。我们将使用新的尖端技术来快速测试轴突保护因子的潜力。我们还必须证实我们在老鼠身上发现了苍蝇(作为哺乳动物，老鼠比苍蝇更像人类，当然，我们最终想要为患者开发治疗方法)。然而，通过在苍蝇身上进行实验，我们将把使用的小鼠数量限制在绝对最低限度。我们还将使用来自肌萎缩侧索硬化症患者的神经细胞，这些神经细胞是通过革命性的干细胞技术从皮肤活检中获得的。我们计划中的研究最令人兴奋的方面之一是，它不仅旨在推动我们对ALS潜在机制的理解，还旨在同时确定在动物模型中保护轴突的方法。因此，这项研究为寻找最终使ALS患者受益的治疗靶点带来了巨大的希望。此外，我们的工作可能会很好地惠及患有一系列其他大脑疾病的患者，这些疾病也表现出轴突变性，并伴有或不伴有TDP-43团块，包括阿尔茨海默病和帕金森病。因此，我们提出的研究有可能使成千上万患有无法治愈和毁灭性的退化性疾病的人受益。

ALS is a devastating, progressive, paralysing disease, which kills over 1200 people in the UK each year, usually within 3-5 years of onset. It usually affects people in their 50s and older, but it can affect adults of any age. Despite decades of research, ALS remains incurable and medical care is essentially palliative (ventilator machines and feeding tubes). The causes of ALS are not fully understood, but in about 10% of cases there may be a family history of ALS suggesting a genetic cause. Excitingly, the past five years has seen an explosion in our understanding of ALS with the discovery of many genes linked to ALS. One of the most important genes is TDP-43. Recent breakthrough research has found that 95% of patients with ALS have clumps of TDP-43 in their brains and spinal cords. In some patients the gene that produces TDP-43 is also mutated and we now believe that TDP-43 plays an important role in causing almost all cases of ALS. Thus, researchers believe that TDP-43 models of ALS will be critical to working out the fundamental causes of ALS, and, ultimately, to develop desperately needed treatments for ALS. Another important consideration for scientists is understanding how ALS begins, because tackling ALS in the early stages is likely to be the most effective way of treating it. ALS is characterised by the loss of nerve cells called motoneurones. These cells have long, delicate processes, called axons, which connect them to other nerve cells and also muscles, allowing us to move, swallow and breathe. In ALS the very earliest signs of disease appear in these axons. We therefore believe that by protecting these axons we can prevent the very earliest stages of ALS. Excitingly, two protective factors have been discovered, which dramatically protect axons when they are cut. However, these factors have never been tested in TDP-43 models of ALS. I plan to test these factors in genetically modified TDP-43 fruitflies and mice, which mimic ALS. I also plan to use these models to find new ways of protecting axons in ALS, which could open up whole new avenues of research. I shall be conducting this research in the labs of Dr Coleman and Dr Freeman, the two world-leading axon experts who discovered these protective factors.Flies are an excellent model for scientists as they have very similar genes to humans, including TDP-43, and have similar types of motoneurons, muscles and brains. We will use novel cutting edge techniques to rapidly test the potential of axon protective factors. We still have to confirm our fly discoveries in mice (as mammals, mice are more similar to humans than flies and of course we ultimately want to develop treatments for patients). However, by starting our experiments in flies, we will limit the numbers of mice we use to an absolute minimum. We will also use nerve cells from patients with ALS, which have been created from skin biopsies using revolutionary stem cell technology. One of the most exciting aspects of our planned research is that it aims to not only push forward our understanding of the mechanisms underlying ALS, it also aims to simultaneously identify ways of protecting axons in animal models. This research therefore holds great promise for finding therapeutic targets that can ultimately benefit patients with ALS. Furthermore, our work may well benefit patients with a whole range of other brain diseases, which also display axon degeneration with or without TDP-43 clumps, including Alzheimer's disease and Parkinson's disease. The research we propose therefore has the potential to benefit many thousands of people with incurable and devastating degenerative diseases.