Protein kinase A modulation of NMDA receptor gating and permeability

说明(申请人提供)：NMDA受体不同于其他谷氨酸受体，因为它们对钙离子具有通透性。这种钙渗透性对于神经元的长期增强是必要的，这是学习和记忆的细胞基础，在中风和癫痫等疾病中也会导致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有助于更深入地了解控制可塑性和兴奋性毒性的过程。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，其中蛋白激酶A(PKA)是这一应用的重点。PKA被证明可以增加NMDA电流的幅度和钙成分，从而影响许多类型的神经元信号，包括长时程增强。然而，PKA调节NMDA受体的机制是完全未知的。因此，在这一应用中，将使用两个AIMS来研究NMDA受体的调节。第一个目标是利用单个NMDA受体记录、药理操作、动力学建模和定点突变来确定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对突触传递、钙内流和长时程增强的影响。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可能如何改变神经元的输出。

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.