VAMP2 associated SNAREopathies: from mechanism to therapeutic approaches

VAMP2 相关的 SNAREopathies：从机制到治疗方法

• 批准号: MR/Y004345/1
• 负责人: Kirill Volynski
• 金额: $ 130.91万
• 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: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FY004345%2F1
• 关键词: VAMP2; associated; SNAREopathies; mechanism; therapeutic

Recent years have seen the discovery of genetic mutations underlying many neurodevelopmental diseases, which, although individually rare, collectively account for a substantial burden to individuals, their families and society. How these mutations result in learning disability, autism, speech problems, and epilepsy is gradually emerging, prompting the search for new treatments to mitigate the symptoms. However, there is an important group of disorders for which the consequences of the mutations at the microscopic level remain very poorly understood: these disorders are caused by mutations that affect how neurons signal to other neurons or muscle cells. Such signalling takes place at synapses and is fundamental for all brain functions, as well as the control of movements and the function of many other organs. At the core of synaptic communication is the precise discharge of packets of chemical messengers (neurotransmitters). We now have a highly detailed understanding of how the so-called SNARE proteins assemble to bring these packets, known as synaptic vesicles, to the membrane and then discharge the neurotransmitter into the synaptic cleft upon arrival of an electrical signal. We refer to the neurodevelopmental disorders caused by defects of SNAREs and functionally associated proteins collectively as 'SNAREopathies'.The goal of our proposal is to understand how these defects alter the discharge of neurotransmitters from synaptic vesicles and the consequences for brain circuit function and also investigate whether these effects could potentially be reversed by harnessing powerful new tools for genetic therapy.An especially difficult challenge for many SNAREopathies is that they are suspected of acting in a genetically dominant manner. That is, if only one of the two copies of the gene encoding a SNARE protein carries a mutation, it may suppress the function of the entire SNARE protein complex, including the normal, unaffected copy of the gene. We have chosen to focus exclusively on mutations of a gene that encodes the essential SNARE protein known as vesicle-associated membrane protein 2, or VAMP2.Our proposal brings together complementary expertise. We are able to characterise the molecular machinery of SNARE proteins by stripping neurotransmitter vesicle trafficking down to the essential steps of assembly of VAMP2 with its partners and the detailed rearrangements that occur upon the arrival of a signal to discharge the vesicle contents. We will combine this approach with highly sensitive measurements of how precisely neurotransmitter is released at individual synapses and how this process is affected by different VAMP2 mutations. We will also address the consequences for the function of small neuronal circuits in a mouse model carrying a human mutation. Finally, guided by a quantitative understanding of how many copies of each of the key molecules interact to support normal vesicle trafficking, we will design a therapy aimed at rescuing the effects of the mutation, and ask which aspects of the disease are potentially amenable to rescue in the mouse model: if the therapy is delivered once symptoms have manifested, can we only suppress seizures, or can we also improve learning and other defects which might have arisen during early development before symptom onset?The proposed research will provide much-needed clarity on the mechanisms of VAMP2 mutations, build towards a viable treatment option which can be translated to the clinic in due course, and define a research pipeline that can be applied to other SNAREopathies.

近年来，人们发现了许多神经发育疾病背后的基因突变，这些疾病虽然个别罕见，但总体上对个人、家庭和社会构成了沉重的负担。这些突变是如何导致学习障碍、自闭症、语言问题和癫痫的，人们正在逐渐发现，这促使人们寻找新的治疗方法来减轻这些症状。然而，有一组重要的疾病，其突变的后果在微观水平上仍然知之甚少：这些疾病是由影响神经元如何向其他神经元或肌肉细胞发送信号的突变引起的。这种信号发生在突触上，是所有大脑功能的基础，也是运动控制和许多其他器官功能的基础。突触通讯的核心是化学信使（神经递质）的精确放电。我们现在已经非常详细地了解了所谓的SNARE蛋白质是如何聚集起来，将这些被称为突触囊泡的包带到膜上，然后在电信号到达时将神经递质释放到突触间隙中。我们将由SNAREs缺陷和功能相关蛋白引起的神经发育障碍统称为“SNAREopathies”。我们建议的目标是了解这些缺陷如何改变突触囊泡的神经递质放电和对脑回路功能的影响，并研究这些影响是否可以通过利用强大的基因治疗新工具来逆转。对于许多SNAREopathies来说，一个特别困难的挑战是，它们被怀疑以基因显性方式起作用。也就是说，如果编码SNARE蛋白的基因的两个拷贝中只有一个携带突变，它可能会抑制整个SNARE蛋白复合物的功能，包括正常的、未受影响的基因拷贝。我们选择专注于一个基因的突变，该基因编码重要的SNARE蛋白，称为囊泡相关膜蛋白2，或VAMP2。我们的提案汇集了互补的专业知识。我们能够通过将神经递质囊泡运输分解为VAMP2与其伙伴组装的基本步骤，以及在信号到达时释放囊泡内容物时发生的详细重排，来表征SNARE蛋白的分子机制。我们将把这种方法与高度敏感的测量方法结合起来，测量神经递质在单个突触上的释放精度，以及这一过程如何受到不同VAMP2突变的影响。我们还将讨论携带人类突变的小鼠模型中小神经元回路功能的后果。最后，在定量了解每个关键分子的多少拷贝相互作用以支持正常囊泡运输的指导下，我们将设计一种旨在挽救突变影响的治疗方法，并询问在小鼠模型中疾病的哪些方面可能可以挽救：如果在症状出现后才进行治疗，我们是否只能抑制癫痫发作，或者我们是否还能改善在症状出现前可能在早期发育中出现的学习和其他缺陷？拟议的研究将为VAMP2突变的机制提供急需的澄清，建立一个可行的治疗方案，可以在适当的时候转化为临床，并定义一个可以应用于其他SNAREopathies的研究管道。