ZINC-DEPENDENT APPARENT DESENSITIZATION NMDA RECEPTORS

锌依赖性表观脱敏 NMDA 受体

• 批准号: 6639611
• 负责人: FANG ZHENG
• 金额: $ 21.3万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-09 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6639611
• 关键词: NMDA receptors; Xenopus; binding sites; chimeric proteins; glutamates; laboratory rat; neurons; point mutation; receptor binding; zinc

Glutamate is the most widely used neurotransmitter in the vertebrate central nervous system. NMDA receptors, a subclass of receptors for glutamate, play a critical role in multiple forms of synaptic plasticity that lay the foundation for learning and memory. NMDA receptors are also implicated in a variety of pathological processes of the brain, including stroke-induced cell death, epilepsy, and degenerative neurological diseases. Thus, detailed knowledge about regulation of NMDA receptor function not only is important for our understanding of synaptic plasticity, but also has broad clinical implications. In the continuous presence of glutamate, NMDA receptors (in particular NR1/NR2A receptors) undergo a process called desensitization that is thought to be an important regulatory mechanism for their function. Preliminary data from this laboratory suggest that ambient zinc, in addition to acting at extracellular high-affinity site to cause voltage-independent inhibition, contributes to apparent desensitization of NR1/NR2A receptors. The goal of this study is to investigate the zinc- dependent desensitization systematically in artificial expression systems and neurons, so we could better understand the underlying mechanism and physiological implication of this phenomenon. One possible mechanism for zinc-dependent desensitization is a positive allosteric interaction between the glutamate-binding site and the extracellular zinc site. This hypothesis will be tested with several biophysical experiments, using recombinant NR1/NR2A receptors expressed in HEK 293 cells. It has also been postulated by us that the zinc-dependent desensitization and glycine-independent desensitization are mediated by distinct molecular determinants. A series of chimeric receptors and point mutants will be used to test this hypothesis. Finally, the effects of zinc on desensitization of native NMDA receptors in cultured neurons will also be investigated. The proposed study may delineate a new mechanism in the regulation of NMDA receptor function, and provide new insight on the functional roles of zinc in the brain. Furthermore, it may provide useful information for the development of new therapeutic agents for stroke, epilepsy and other neurological diseases.

谷氨酸是脊椎动物中枢神经系统中使用最广泛的神经递质。 NMDA 受体是谷氨酸受体的一个子类，在多种形式的突触可塑性中发挥着关键作用，为学习和记忆奠定了基础。 NMDA 受体还与大脑的多种病理过程有关，包括中风引起的细胞死亡、癫痫和退行性神经系统疾病。因此，关于 NMDA 受体功能调节的详细知识不仅对于我们理解突触可塑性很重要，而且具有广泛的临床意义。在谷氨酸持续存在的情况下，NMDA 受体（特别是 NR1/NR2A 受体）会经历一种称为脱敏的过程，这被认为是其功能的重要调节机制。 该实验室的初步数据表明，环境锌除了作用于细胞外高亲和力位点引起电压非依赖性抑制外，还有助于 NR1/NR2A 受体的明显脱敏。 本研究的目的是系统地研究人工表达系统和神经元中的锌依赖性脱敏，以便我们更好地理解这种现象的潜在机制和生理意义。 锌依赖性脱敏的一种可能机制是谷氨酸结合位点和细胞外锌位点之间的正变构相互作用。 该假设将通过多个生物物理实验进行检验，使用 HEK 293 细胞中表达的重组 NR1/NR2A 受体。 我们还假设锌依赖性脱敏和甘氨酸非依赖性脱敏是由不同的分子决定因素介导的。 一系列嵌合受体和点突变体将用于检验这一假设。 最后，还将研究锌对培养神经元中天然 NMDA 受体脱敏的影响。这项研究可能描绘出 NMDA 受体功能调节的新机制，并为锌在大脑中的功能作用提供新的见解。 此外，它还可以为开发中风、癫痫和其他神经系统疾病的新治疗药物提供有用的信息。