Allosteric control of NMDA receptors

描述（由申请人提供）：NMDA受体（NRs）介导大脑中的快速兴奋传递。它们的激活对于兴奋性突触的正常发育、维持和持续重塑至关重要。过度的NR活性是卒中、慢性疼痛、癫痫和神经退行性疾病的发病机制，而NR信号传导不足则与精神分裂症和认知障碍有关。许多内源性和药理学药物调节NR活性，是治疗干预的潜在候选者。调控NR活性变构控制的机制尚不清楚，迄今为止，控制NR功能的经验尝试产生了令人失望的结果。目的是了解变构调节剂如何从分子机制、整合和对突触生理的影响方面控制NR生理功能。本提案中涉及的目标是：i)表征单个NR变构调制器对NR门控动力学和非平稳宏观行为的影响；Ii)确定如何整合多个变构信号以产生具有不同信号谱的响应；iii)研究NR反应的变构调节如何影响突触生理学。首先，利用单通道电流的动力学分析和统计建模，我们将确定和量化各个调制器在门控过程中对NR基本动力学转变的作用。这些测量的速率常数本质上具有丰富的力学信息；此外，它们还可以预测NR宏观行为和NR介导的突触功能的调节作用。这些预测将通过在切除的膜斑块中测量整体NR对模式刺激的反应和在脑切片中测量诱发的NR突触反应来验证。对于激活反应复杂的NRs，这种方法是全新的，可以确定在彼此分离时调节特定受体功能的有效手段。综上所述，这些结果将有助于对NR活动的变构控制如何影响突触生理形成一个完整的机制观点。这一观点应该提出新的、组合的方法来专门针对有害受体的行为，同时保留NRs发挥的关键功能。

DESCRIPTION (provided by applicant): NMDA receptors (NRs) mediate fast excitatory transmission in the brain. Their activation is critical for the normal development, maintenance and continual remodeling of excitatory synapses. Excessive NR activity is a disease mechanism in stroke, chronic pain, epilepsy, and neurodegenerative disease, whereas insufficient NR signaling has been involved with schizophrenia and cognitive disorders. Numerous endogenous and pharmacologic agents modulate NR activities and are potential candidates for therapeutic intervention. The mechanisms governing the allosteric control of NR activity are poorly understood and empirical attempts to control NR function have so far yielded disappointing results. The OBJECTIVE is to understand how allosteric modulators control NR physiologic functions in terms of molecular mechanisms, integration and consequences on synaptic physiology. The AIMS addressed in this proposal are to: i) characterize individual NR allosteric modulators in terms of their effects on NR gating dynamics and on non-stationary macroscopic behaviors; ii) establish how multiple allosteric signals are integrated to result in responses with distinct signaling profiles; and iii) investigate how allosteric modulation of NR responses impacts on synaptic physiology. First, using kinetic analysis of single-channel currents and statistical modeling we will identify and quantify the actions of individual modulators on NR elementary kinetic transitions during gating. These measured rate constants are intrinsically rich with mechanistic information; in addition they can predict modulator effects on NR macroscopic behaviors and on NR- mediated synaptic function. These predictions will be verified by measuring ensemble NR responses to patterned stimulation in excised membrane patches and by measuring evoked NR synaptic responses in brain slices. For NRs whose activation reaction is complex, this approach is entirely novel and may identify effective means to modulate specific receptor functions in separation of each other. Taken together the results will help to compile an integrated mechanistic view of how allosteric control of NR activity impacts synaptic physiology. This view should suggest new, combinatorial approaches to specifically target harmful receptor behaviors while preserving the critical functions played by NRs .