Metal-ion-based neurodegeneration: enabling techniques for understanding, detection, and treatment

随着时间的推移，人类大脑的许多疾病会导致组织退化和功能丧失。当一个人因为功能丧失（无论是认知还是身体）而被检测到这种疾病时，在许多情况下已经发生了广泛的退化。扭转这种退化是一项巨大的挑战；该项目的目标是专注于了解导致变性的因素，并找到在早期阶段识别变性的方法，以便i)提高检测，ii)为有效治疗提供新的目标。许多神经退行性疾病，如阿尔茨海默氏症、帕金森氏症、亨廷顿氏症、运动神经元疾病和多系统萎缩，都有一个共同的主题，即某些微量金属的调节和/或负责结合和利用这些金属元素的蛋白质的变化是明显的。这可能包括某些元素的积累，如铁，在大脑的特定区域。我们的假设是，这些变化是疾病特异性的，如果更好地理解，可能会为改进检测和治疗提供机会。影响这一领域目前工作的限制因素包括：i)从实验室简单实验的发现推断大脑生化环境的复杂性的挑战；Ii)对大脑中痕量金属元素进行准确灵敏检测的挑战——无论是使用临床技术对活体大脑进行测量，还是对脑组织进行实验室分析。在拟议的研究中，将进行实验和基于计算机的建模相结合，以描述、预测和测试预计在某些神经退行性疾病中受到影响的微量金属调节机制。这些模型将使用从实验工作中已经知道的东西来构建，包括其他研究小组发表的数据。反过来，随着本项目中开发的模型做出预测，将设计和执行实验来测试预测并相应地更新模型。观察金属结合蛋白与影响其聚集的微量金属之间相互作用的实验，将通过在专门设计的“微流体”系统中研究它们而变得更具生理学相关性：实验系统设计用于处理极小体积（微升或纳升）的样品。在这种情况下，微流体系统有三个特别的优势：1)它们允许比通常情况下研究的样本量少得多，2)它们允许对单个批次蛋白质的许多实验条件进行高通量测试，从而提高了效率并减少了结果的模糊性，3)可以实现的非常小的体积和对界面的控制使得比以前更准确地模拟生理条件成为可能。非常敏感的分析微量金属在组织将实现在实验中使用英国同步加速器设施。这些提供了极其明亮的x射线束，可以聚焦到微米或亚微米的直径进行测绘。光束激发来自特定元素（如铁、铜和锌）的自然荧光信号，使沉积模式能够被映射到每种元素，即使微量浓度仅为百万分之几。预计本项目中解决的具体问题将有助于我们进一步了解铁如何影响帕金森病路易体病理中发现的特定蛋白质的聚集，并将有助于了解某些神经退行性疾病如何（以及在何处）影响脑铁储存，以评估是否有足够的差异来检测这些疾病，并区分彼此。使用磁共振成像。

Many diseases of the human brain lead, over time, to degeneration of tissue and loss of function. By the time the disease is detected in an individual because of loss of function (whether cognitive or physical), extensive degeneration has in many instances already taken place. Reversing this degeneration presents an enormous challenge; the goal of this project is instead to focus on understanding factors that contribute to causing the degeneration, and to find ways of identifying the degeneration at an early stage in order to i) improve detection, and ii) offer new targets for effective treatment. A common theme linking many neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, Motor Neurone Disease, and Multiple System Atrophy, is that changes in the regulation of certain trace metals, and/or the proteins responsible for binding and utilizing these metal elements, are apparent. This can include accumulation of certain elements, such as iron, in specific regions of the brain. Our hypothesis is that these changes are disease-specific, and if better understood, may provide windows of opportunity for improved detection and treatment.Limiting factors affecting present work in this area include:i) the challenge of extrapolating findings from simple experiments in the laboratory to the complexity of the biochemical environment in the brain;ii) the challenge of accurate sensitive detection of trace metal elements in the brain - both for measurement in the living brain using clinical techniques, and for laboratory analysis of brain tissue. In the proposed research, a combination of experiments and computer-based modelling will be undertaken, in order to describe, predict, and test mechanisms of trace metal regulation that are anticipated to be affected in some of these neurodegenerative disorders. The models will be constructed using what is already known from experimental work, including published data from other research groups. In turn, as predictions are made by the models developed in this project, experiments will be designed and performed to test the predictions and update the models accordingly.Experiments to look at the interactions between metal-binding proteins and the trace metals that affect their aggregation, will be made more physiologically relevant by studying them in purpose-designed 'microfluidic' systems: experimental systems engineered to enable work with extremely small volumes (micro- or nanolitres) of sample. Microfluidic systems have three particular advantages in this context: i) they allow much smaller amounts of sample to be studied than would normally be the case, ii) they permit high-throughput testing of many experimental conditions for a single batch of protein which improves efficiency and reduces ambiguity in the results, and iii) the very small volumes and control of interfaces that can be achieved make it possible to mimic physiological conditions more accurately than has previously been possible.Very sensitive analysis of trace metals in tissues will be achieved in experiments using UK synchrotron facilities. These provide extremely bright beams of X-rays that can be focussed to micron or sub-micron diameters for mapping. The beams excite natural fluorescence signal from specific elements such as iron, copper, and zinc, enabling patterns of deposition to be mapped for each element even for trace concentrations of just a few parts per million. It is anticipated that the specific questions addressed in this project will help further our understanding of how iron affects the aggregation of a particular protein found in Lewy body pathology in Parkinson's disease, and will also enable progress in understanding how (and where) brain iron storage is affected in certain neurodegenerative disorders, to assess if there are sufficient differences for these diseases to be detected, and distinguished from each other, using Magnetic Resonance Imaging.