Protein kinase A modulation of NMDA receptor gating and permeability

描述（由申请人提供）：NMDA受体与其他谷氨酸受体的独特之处在于它们对钙具有渗透性。这种钙的渗透性对于神经元的长期增强（学习和记忆的细胞基础）是必要的，也可能在中风和癫痫等疾病中引起兴奋性毒性和细胞死亡。因此，了解影响NMDA受体门控和通透性的机制将为控制可塑性和兴奋毒性的过程提供更多的见解。NMDA受体的门控和通透性受到多种细胞外和细胞内信号的影响，包括蛋白激酶a (PKA)，这是本应用的重点。PKA已被证明可以增加NMDA电流的振幅和钙成分，从而影响许多类型的神经元信号传导，包括长期增强。然而，PKA调节NMDA受体的机制是完全未知的。因此，在本应用中，NMDA受体的调节将使用两个目的进行研究。第一个目标是通过使用单个NMDA受体记录、药理学操作、动力学建模和位点定向诱变来确定PKA调节NMDA受体门控和通透性的机制。在第二个目标中，将研究PKA调节对突触传递、钙内流和长期增强的影响。因此，这些实验的结果将确定PKA改变NMDA受体门控的机制，并深入了解这种调节最终如何改变神经元输出。

DESCRIPTION (provided by applicant): NMDA receptors are unique from other glutamate receptors in that they are permeable to calcium. This calcium permeability is necessary for neuronal long-term potentiation, the cellular basis of learning and memory, and can also cause excitotoxicity and cell death in disease conditions like stroke and epilepsy. Therefore understanding mechanisms that influence gating and permeability of NMDA receptors will provide more insight into the processes that control plasticity and excitotoxicity. The gating and permeability of NMDA receptors are influenced by a variety of extracellular and intracellular signals, including protein kinase A (PKA), which is the focus of this application. PKA has been shown to increase both the amplitude and calcium component of NMDA currents, which then influences many types of neuronal signaling, including long-term potentiation. The mechanism by which PKA modulates NMDA receptors, however, is completely unknown. In this application, therefore, modulation of NMDA receptors will be investigated using two aims. The goal of the first aim is to determine the mechanism by which NMDA receptor gating and permeability are modulated by PKA using single NMDA receptor recordings, pharmacological manipulations, kinetic modeling, and site- directed mutagenesis. In the second aim, the effect of PKA modulation on synaptic transmission, calcium influx, and long-term potentiation will be investigated. The results of these experiments will therefore determine the mechanism by which PKA alters NMDA receptor gating and give insight as to how this modulation may ultimately change neuronal output. PUBLIC HEALTH RELEVANCE: Calcium influx into neurons through NMDA receptors causes a variety of effects, including neuronal plasticity, the cellular basis of learning, as well as cel death in conditions like epilepsy and stroke. This application will investigate one mechanism by which NMDA receptor activity, particularly calcium influx, is regulated by a kinase pathway. Understanding the mechanisms by which NMDA gating and calcium influx is modulated will therefore give more insight into the mechanisms of learning and memory, as well as potential methods to prevent cell death in various disease states.