Mechanism and therapy in DNM1 epileptic encephalopathy

DNM1癫痫性脑病的机制和治疗

• 批准号: MR/Y014340/1
• 负责人: Michael Cousin
• 金额: $ 111.83万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FY014340%2F1
• 关键词: Mechanism; therapy; DNM1; epileptic; encephalopathy

Brain cells (neurons) communicate by releasing chemical neurotransmitters. Neurotransmitters are stored in small spherical compartments within neurones called synaptic vesicles (SVs). When neurones communicate, SVs fuse with the outer surface of the neuron causing neurotransmitter release. After neurotransmitter release, these SVs are reformed by a process called endocytosis. The correct formation of SVs during endocytosis is essential for the maintenance of neurotransmitter release, since SVs are highly limited in neurons. It was originally thought that dysfunction in such an essential process would result in death of the affected individual, however over the past 10 years it is now becoming apparent that defective endocytosis underpins a series of severe forms of epilepsy called epileptic encephalopathies (EEs). As things currently stand, there are no available therapies for many individuals with EE, making understanding disease mechanisms an essential first step in generating new drugs. Mutations in the gene DNM1, are causal in a form of EE. The DNM1 gene makes a protein called dynamin-1, which is essential for SV endocytosis. As a first step in unravelling how a mutation in a gene essential for endocytosis results in EE, we generated a mouse that carries the most common human DNM1 mutation. Neurons from this mouse displayed dysfunctional SV endocytosis, and in addition had over-excitable brain activity and seizure-like behaviour. Therefore we now have an experimental tool through which to determine how epilepsy develops and in which to test new drugs. In previous work we identified a drug approved for human use that accelerates SV endocytosis. We discovered that this drug also corrected all of the defects in our mouse model of DNM1 EE (SV endocytosis, brain excitability and seizure-like events). Because it is likely that this drug affects SV endocytosis rather than dynamin-1 function itself, it has potential to be widely used in other disorders of SV endocytosis. In this programme of work we will determine how this drug works, and test its wider therapeutic potential in different models of dysfunctional SV endocytosis. People have two copies of every gene, called alleles. Individuals that have DNM1 EE only have 1 mutant allele, the other is unaffected. Interestingly, people can tolerate the complete loss of one DNM1 allele providing the other one is functional, suggesting that 1) the mutant form usually overrides the function of the unaffected version and 2) removal of the mutant allele may be a promising approach to treat the disorder. We will test this hypothesis by using gene therapy to remove the mutant DNM1 allele from the mouse model to determine whether this corrects the defects seen. A determination of how mutant DNM1 causes EE is essential to obtain, since it will provide key data on how to treat this, and other related conditions. The gene therapy approach detailed above will be critical to address this question, since we can remove the mutant DNM1 allele from specific types of neurons to determine how it is causing EE. This will be critical in determining epilepsy mechanisms. Many different mutations in the DNM1 gene have been discovered, therefore it is essential to determine whether there are similarities in how they affect dynamin-1 function and importantly how they change the function of neurons. We will also determine whether these mutations have similarities in terms of their effect, which will be highly informative in terms of future therapies.

脑细胞（神经元）通过释放化学神经递质进行交流。神经递质储存在神经元内称为突触囊泡（SV）的小球形隔室中。当神经元交流时，SV与神经元的外表面融合，引起神经递质释放。在神经递质释放后，这些SV通过称为内吞作用的过程重新形成。内吞过程中SV的正确形成对于维持神经递质释放至关重要，因为SV在神经元中高度受限。最初认为在这样一个重要过程中的功能障碍会导致受影响个体的死亡，然而在过去的10年中，现在变得明显的是，有缺陷的内吞作用是一系列严重形式的癫痫的基础，称为癫痫性脑病（EE）。就目前情况而言，许多EE患者没有可用的治疗方法，这使得了解疾病机制成为产生新药的重要第一步。 DNM 1基因的突变是EE的一种形式。DNM 1基因产生一种称为发动蛋白-1的蛋白质，该蛋白质对SV内吞作用至关重要。作为解开内吞作用所必需的基因突变如何导致EE的第一步，我们产生了一只携带最常见的人类DNM 1突变的小鼠。这只小鼠的神经元显示出功能失调的SV内吞作用，此外还具有过度兴奋的脑活动和神经元样行为。因此，我们现在有一个实验工具，通过它来确定癫痫如何发展，并在其中测试新药。在以前的工作中，我们确定了一种批准用于人类使用的药物，可以加速SV内吞作用。我们发现，这种药物还纠正了我们的DNM 1 EE小鼠模型中的所有缺陷（SV内吞作用，脑兴奋性和神经元样事件）。由于这种药物可能影响SV内吞作用而不是发动蛋白-1本身的功能，因此它有可能广泛用于SV内吞作用的其他疾病。在这项工作计划中，我们将确定这种药物是如何工作的，并在不同的功能失调的SV内吞模型中测试其更广泛的治疗潜力。 每个人的基因都有两个副本，称为等位基因。具有DNM 1 EE的个体仅具有1个突变等位基因，其他不受影响。有趣的是，人们可以容忍一个DNM 1等位基因的完全丢失，只要另一个是功能性的，这表明1）突变形式通常覆盖未受影响版本的功能，2）去除突变等位基因可能是治疗这种疾病的一种有希望的方法。我们将通过使用基因疗法从小鼠模型中去除突变的DNM 1等位基因来测试这一假设，以确定这是否纠正了所观察到的缺陷。确定突变体DNM 1如何导致EE是至关重要的，因为它将提供如何治疗这种疾病和其他相关疾病的关键数据。上述基因治疗方法对于解决这个问题至关重要，因为我们可以从特定类型的神经元中去除突变的DNM 1等位基因，以确定它是如何引起EE的。已经发现了DNM 1基因中的许多不同突变，因此确定它们如何影响dynamin-1功能以及重要的是它们如何改变神经元功能方面是否存在相似性是至关重要的。我们还将确定这些突变在其作用方面是否具有相似性，这将在未来的治疗方面提供大量信息。