Elucidating early stage ALS pathomecanisms that drive mitochondrial dysfunction

运动神经元是从脊髓向我们的肌肉发送信号的神经。肌萎缩侧索硬化症(ALS)是人体内最大的神经细胞之一，高度专业化，因为它们的细胞体位于脊髓内，其纤维(称为轴突)投射到肌肉外；这些细胞具有巨大的能量需求，因为它们如此巨大和活跃。肌萎缩侧索硬化症(ALS)是一种无情的不可治愈的疾病，会杀死运动神经元，导致进行性瘫痪和死亡，通常在确诊后5年内。在英国人口中，肌萎缩侧索硬化症的终生风险为每250人中就有一人患有肌萎缩侧索硬化症，尽管它主要被认为是一种中年疾病，但年仅11岁的儿童都被诊断出患有肌萎缩侧索硬化症。我们迫切需要为这种疾病找到某种治疗方法--然而，我们还不知道肌萎缩侧索硬化症中运动神经元死亡的根本原因，甚至还不知道疾病过程何时开始，所以我们无法通过有针对性的治疗来解决这些过程。我们体内的每个细胞都含有DNA、RNA和蛋白质。DNA位于细胞的细胞核中，携带着如何构建蛋白质的信息。蛋白质是我们细胞的基石，它们也可以为细胞的正常运作执行重要的任务。RNA是中间体，将从DNA制造单个蛋白质的指令携带到细胞内制造这些蛋白质的不同位置，这些蛋白质是特定工作所需的。90%的肌萎缩侧索硬化症是零星的--发生在没有家族病史的人身上。然而，约10%发生在家庭中，通常如果父母中的一人受到影响，孩子患ALS的可能性为50%。在这些家族性病例中，有许多突变基因可以导致ALS。其中一些基因发出指令，制造与RNA结合的蛋白质，使RNA在细胞中正常工作。虽然我们知道几个这样的‘RNA结合蛋白’可以在肌萎缩侧索硬化症中突变，并导致运动神经元死亡，但我们不知道这种情况是如何发生的，或者它什么时候开始发生。在这里，我们创建了一个独特的系统，用于开始了解为什么运动神经元在一种形式的家族性肌萎缩侧索硬化症中死亡，这是由一种名为‘FUS’的RNA结合蛋白的突变引起的。这个系统是基于一种新的抗体，它只与突变的FUS蛋白结合。我们有一个FUS小鼠模型-它有一种被抗体识别的人类突变-导致动物进行性运动神经元丢失。我们现在将用同样的突变制造一个互补的人类细胞系。拥有这种抗体意味着我们现在可以看到突变的FUS与正常的FUS蛋白的行为是如何不同的。我们可以开始了解突变蛋白参与了什么异常过程，以及这些异常过程在运动神经元和其他细胞中发生的地方。这个抗体系统已经告诉我们，蛋白质和能量平衡以及脂肪的变化发生得很早，在我们的小鼠模型中看到运动神经元死亡之前。因此，与我们的系统合作，并将我们的发现与我们的人类FUS-ALS细胞进行比较，将有助于我们对ALS的理解，特别是在运动神经元死亡之前的早期阶段。这项研究将帮助我们针对这种形式的肌萎缩侧索硬化症的治疗，我们相信，也有助于阐明由异常的RNA结合蛋白引起的其他形式的肌萎缩侧索硬化症。

Motor neurons are the nerves that send signals from the spinal cord to our muscles. They are amongst the largest nerve cells in the body and are highly specialized, in that their cell body is located in the spinal cord and its fibre (called the 'axon') projects outside to the muscles; these cells have huge energy demands because they are so big and active.Amyotrophic Lateral Sclerosis (ALS) is a relentless and incurable disease that kills the motor neurons, resulting in progressive paralysis and death typically within 5 years of diagnosis. ALS has a lifetime risk of 1 in 250 in the UK population, and although it is mainly considered a disorder of mid-life, children as young as 11 years of age have been diagnosed with ALS. We have a desperate need to find some kind of treatment for this disease - however, we do not yet know the fundamental reasons why motor neurons die in ALS, or even when the disease processes start, so we cannot tackle these processes with targeted therapies.Every cell in our body contains DNA, RNA and proteins. DNA is in the nucleus of cells and carries the information on how to build the proteins. Proteins are the building block of our cells and they can also perform important tasks for the normal functioning of cells. RNA is the intermediate and carries the instructions for making individual proteins from the DNA, to the various locations inside a cell where these proteins are made and needed for specific jobs.90% of ALS is 'sporadic' -- it occurs in people who have no family history of the disease. However, ~10% occurs in families and usually if a parent is affected there is a 50% chance a child will have ALS. There are many mutant genes that can cause ALS in these familial cases. Some of these genes give the instructions to make proteins that bind to RNA and enable RNA to work properly in the cell. While we know that several of these 'RNA binding proteins', can be mutated in ALS, and cause motor neurons to die, we do not know how this happens, or when it begins.Here, we have created a unique system, for starting to understand why motor neurons die in one form of familial ALS, caused by mutations in an RNA binding protein called 'FUS'. This system is based on a new antibody that just binds to the mutant FUS protein. We have a FUS mouse model - which has a human mutation recognised by the antibody - that causes progressive motor neuron loss in the animal. We will now make a complementary human cell line with the same mutation. Having this antibody means we can now look at how mutant FUS behaves differently from the normal FUS protein. We can start to see what aberrant processes the mutant protein is involved in, and where these happen in the motor neuron and other cells.This antibody system has already told us that changes in proteins and energy balance, and in fats, occur early, before we see motor neuron death in our mouse model. Thus, working with our system, and comparing our findings with our human FUS-ALS cells, will make an important contribution to our understanding of ALS, particularly in the early stages before motor neurons have died. This this research will help us to target therapies in this form of ALS, and, we believe, shed light on other forms of ALS that arise from aberrant RNA binding proteins.