Targeting Kir4.1 To Control Brain Excitability And Seizures

以 Kir4.1 为目标来控制大脑兴奋性和癫痫发作

基本信息

批准号：
MR/W019752/1
负责人：
Dmitri Rusakov
金额：
$ 99.03万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2022
资助国家：
英国
起止时间：
2022 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=MR%2FW019752%2F1
关键词：
Targeting Kir4.1 Control Brain Excitability

项目摘要

Neuronal activity can rapidly elevate extracellular potassium in the brain. Potassium elevations are mechanistically related to increases in nerve cell excitability, potentially leading to abnormal network behaviours such as in epilepsy. Astroglia are essential for maintaining potassium balance, through a buffering mechanism engaging their sodium-potassium pumps. However, new evidence attributes the dynamic regulation of extracellular potassium mainly to astroglial channels of the Kir4.1 type whereas downregulation of these channels has been associated with enhanced seizure susceptibility and, in the long term, sclerotic abnormalities of brain tissue. Despite the importance of Kir4.1 for brain excitability control, the causal relationships between Kir4.1 expression, potassium dynamics, local neuronal excitability and synaptic function remain poorly understood. The lack of progress stems from the poorly understood and often counteracting consequences of extracellular potassium rises, from the lack of tools to monitor potassium dynamics in brain tissue, and from the poor access to the sponge-like, nanoscopic morphology of astroglia. The main goal of the present proposal is therefore to understand how the Kir4.1-dependent potassium buffering by astrocytes regulates neural excitability and synaptic circuit function, and whether targeting these mechanisms, pharmacologically or genetically, can alter susceptibility to runaway excitation and seizures. Thus, the central hypothesis is that the varied expression of astroglial Kir4.1 regulates, in a mechanistically predictable manner, cell excitability and synaptic signal transfer. The key translational aspect of the proposal is that the controlled manipulation of Kir4.1 expression should ameliorate pathological changes in neural excitability, such as those during epilepsy or cortical spreading depression. To achieve our goal, we will take advantage of our novel and cutting-edge experimental and theoretical approaches. We have established gene-targeting protocols to enable single-cell studies in Kir4.1-overexpressing astrocytes while simultaneously monitoring neurotransmitter release at local synaptic connections. We have embarked on a novel nanoengineering technology to monitor potassium, which involves encapsulation of the ratiometric optical sensor into ion-permeable, biologically compatible microcapsules. We have established a novel biophysical modelling platform that enables theoretical probing of the intra- and extracellular potassium dynamics in realistic astrocyte models. We have developed a novel multi-electrode electrocorticography technique based on flexible graphene transistor arrays enabling full-band current recordings in awake animals. These and related methodological breakthroughs, backed by a large body of pilot and proof-of-principle data, helped us to formulate a feasible research strategy for achieving our main goal. The plan includes five specific objectives addressed in five work packages. The results will provide new knowledge about the mechanisms by which astroglia regulate neuronal excitability through the Kir4.1-dependent control of extracellular potassium dynamics. Based on such knowledge, a therapeutic strategy could be developed that helps reduce brain susceptibility to runaway excitation, such as seen in epilepsy and related disorders.

神经元活动可以迅速升高大脑中的细胞外钾。钾升高在机制上与神经细胞兴奋性的增加有关，可能导致异常的网络行为，例如癫痫。星形胶质细胞通过钠钾泵的缓冲机制维持钾平衡至关重要。然而，新的证据将细胞外钾的动态调节主要归因于 Kir4.1 类型的星形胶质细胞通道，而这些通道的下调与癫痫易感性增强以及从长远来看与脑组织硬化异常有关。尽管 Kir4.1 对于大脑兴奋性控制很重要，但 Kir4.1 表达、钾动力学、局部神经元兴奋性和突触功能之间的因果关系仍然知之甚少。缺乏进展的原因在于人们对细胞外钾升高的认识知之甚少，而且常常会产生抵消作用，缺乏监测脑组织中钾动态的工具，以及难以获得海绵状、纳米级的星形胶质细胞形态。因此，本提案的主要目标是了解星形胶质细胞的 Kir4.1 依赖性钾缓冲如何调节神经兴奋性和突触回路功能，以及是否从药理学或遗传上针对这些机制，可以改变对失控兴奋和癫痫发作的易感性。因此，中心假设是星形胶质细胞 Kir4.1 的不同表达以机械可预测的方式调节细胞兴奋性和突触信号传递。该提案的关键转化方面是，Kir4.1 表达的受控操作应该改善神经兴奋性的病理变化，例如癫痫或皮质扩散性抑郁期间的病理变化。为了实现我们的目标，我们将利用我们新颖且前沿的实验和理论方法。我们已经建立了基因靶向方案，以便能够在 Kir4.1 过表达的星形胶质细胞中进行单细胞研究，同时监测局部突触连接处的神经递质释放。我们已经开始采用一种新颖的纳米工程技术来监测钾，该技术涉及将比率光学传感器封装到离子可渗透的、生物相容的微胶囊中。我们建立了一个新颖的生物物理建模平台，可以对现实星形胶质细胞模型中的细胞内和细胞外钾动力学进行理论探索。我们开发了一种基于柔性石墨烯晶体管阵列的新型多电极皮层电描记技术，可在清醒动物中进行全频带电流记录。这些和相关的方法论突破，在大量试点和原理验证数据的支持下，帮助我们制定了可行的研究策略来实现我们的主要目标。该计划包括五个工作包中涉及的五个具体目标。这些结果将提供关于星形胶质细胞通过 Kir4.1 依赖的细胞外钾动力学控制来调节神经元兴奋性的机制的新知识。基于这些知识，可以开发出一种治疗策略，帮助降低大脑对失控兴奋的敏感性，例如癫痫和相关疾病。