L-aspartate signalling in the brain

项目概述：这个mrc资助的博士培训伙伴关系（DTP）将尖端的分子和分析科学与创新的数据分析计算方法结合在一起，使学生能够与工业界合作进行重要的应用生物医学研究。这是一个为期4年的课程，第一年包括一系列教学模块和两个基于实验室的研究项目，最终获得跨学科生物医学研究硕士学位。前两个学期包括一系列教学模块，让学生在多学科科学方面打下坚实的基础。学生还将参加一系列由分子、细胞和组织动力学、微生物学和感染、应用生物医学技术、人工智能和数据科学等领域的学术和行业专家主持的大师班。在第三学期和夏季学期，学生在他们选择的实验室进行两个为期11周的研究项目。项目：l -天冬氨酸被认为是一种兴奋性神经递质，但它作为兴奋性神经递质的作用在很大程度上被谷氨酸所忽视，谷氨酸是一种公认的兴奋性氨基酸神经递质。通过使用一种新的l -天冬氨酸生物传感器，我们发现将l -天冬氨酸转化为l -天冬氨酸的细胞内酶——天冬氨酸合成酶（ASNS）是细胞外天冬氨酸的关键决定因素。阻断ASNS通过nmda受体依赖过程导致海马脑切片细胞外l -天冬氨酸的积累和癫痫样活动的发展。人类ASNS突变与小头畸形、认知障碍和慢性癫痫有关。我们的数据表明，这种表型的一些可能是由于l -天冬氨酸的过度积累。本项目将继续研究l -天冬氨酸在海马和皮质脑片中的释放机制和环境，ASNS阻断的影响，以及介导l -天冬氨酸从细胞外空间移除的转运体的身份。由于ASNS功能缺陷与癫痫有关，我们将在对照小鼠和癫痫小鼠的组织中检测l -天冬氨酸的释放。细胞外l -天冬氨酸的积累通过NMDA受体激活导致癫痫发作活动的发展。通过使用有效的和特定的药理学工具，NMDA受体亚型将被确定。由于某些NMDA受体亚型仅在海马体中非常特定的细胞类型上表达，这一重要步骤将有助于阐明与l -天冬氨酸诱导的癫痫活动有关的细胞回路。通过了解控制细胞外l -天冬氨酸的分子机制，该项目将为其生理作用以及天冬氨酸信号紊乱如何导致癫痫提供新的见解。

Programme overview:This MRC-funded doctoral training partnership (DTP) brings together cutting-edge molecular and analytical sciences with innovative computational approaches in data analysis to enable students to undertake important applied biomedical research in partnership with industry. This is a 4-year programme whose first year involves a series of taught modules and two laboratory-based research projects that lead to an MSc in Interdisciplinary Biomedical Research. The first two terms consist of a selection of taught modules that allow students to gain a solid grounding in multidisciplinary science. Students also attend a series of masterclasses led by academic and industry experts in areas of molecular, cellular and tissue dynamics, microbiology and infection, applied biomedical technologies and artificial intelligence and data science. During the third and summer terms students conduct two eleven-week research projects in labs of their choice. Project:L-aspartate has been suggested as an excitatory neurotransmitter but, its contribution as an excitatory neurotransmitter has largely been discounted on favour of glutamate, the universally recognised excitatory amino acid neurotransmitter. By using a new biosensor for L-aspartate, we have discovered that the intracellular enzyme, asparagine synthetase (ASNS), which converts L-aspartate to L-asparagine, is a key determinant of extracellular aspartate. Blockade of ASNS leads to accumulation of extracellular L-aspartate and development of seizure-like activity in hippocampal brain slices via an NMDA-receptor dependent process. Human mutations of ASNS are linked to microcephaly, cognitive impairment and chronic epilepsy. Our data suggests that some of this phenotype could be due to excessive accumulation of L-aspartate.This project will continue our study of the mechanisms and circumstances of L-aspartate release in hippocampal and cortical brain slices, the effects of blockade of ASNS, and the identity of the transporters that mediate the removal of L-aspartate from the extracellular space. As defective function of ASNS is linked to epilepsy, L-aspartate release will be examined in tissue from both control and epileptic mice. Accumulation of extracellular L-aspartate results in the development of seizure activity via the NMDA receptor activation. By using potent and specific pharmacological tools, the NMDA receptor subtypes involved will be established. As certain NMDA receptor subtypes are expressed only on very specific cell types in the hippocampus, this important step will help to elucidate the cellular circuitry involved in L-aspartate induced seizure activity. By understanding the molecular mechanisms that control extracellular L-aspartate this project will provide new insight into its physiological actions and how disorders of asparate signalling can lead to epilepsy.