Mechanisms of cAMP dependent potentiation of mossy fiber synapses

海马区的突触可塑性对情景记忆的形成、存储和提取至关重要。 海马体的不同区域已经进化成在空间导航、上下文 记忆，社会记忆，以及我们分离模式或完整模式重建部分的能力 回忆。特别是，海马齿状区和CA3区参与了我们的模式分离 这对情节记忆的完整性至关重要。在这个区域的中心是苔藓纤维传入 使条件性雷管突触到达CA3锥体神经元，这些神经元具有一种不同形式的突触前 CAMP依赖的可塑性。尽管cAMP可塑性对记忆的形成和恢复具有重要意义 CA3 MFLTP的确切分子机制尚未被揭示。这样做的前提是 研究基于我们的发现，至少有两个下游的cAMP效应器，PKA(蛋白激酶 A)和Epac2(由cAMP 2直接激活的交换蛋白)，参与cAMP依赖的MF LTP。 尽管有这些发现，但仍然不知道这些效应器的信号如何导致释放增加 MFLTP的重要靶点和底物是什么？ 在这里，我们将使用一种综合的方法，结合前沿的蛋白质组学、生化和 电生理学方法来确定cAMP效应器的信号伙伴，并揭示 它们的作用的生理机制。因此，在目标1中，我们将采用正交方法来找出 PKA和Epac2的相互作用子和底物，并通过执行高分辨率来验证和验证它们 原位标记。在目标2中，我们将确定增长的确切生理机制。 利用光遗传-基因敲除/药理学联合策略在MF突触释放神经递质。 在最终目标中，我们将回答这些不同但趋同的机制是如何运作的问题 在自然主义活动模式中，以及选择性干扰这些效应器是否会损害 小鼠将构成情节记忆形成和恢复的相似模式分开。

Synaptic plasticity in the hippocampus is critical to the formation, storage and retrieval of episodic memories. The separate regions of the hippocampus have evolved to play distinct roles in spatial navigation, contextual memories, social memories, and our ability to separate patterns or complete patterns to reconstruct partial memories. In particular the dentate and CA3 regions of the hippocampus are involved in our pattern separation that is vital to the integrity of episodic memories. At the center of this region are the mossy fiber afferents that make conditional detonator synapses onto CA3 pyramidal neurons, which have a distinct form of presynaptic cAMP dependent plasticity. Despite the importance of cAMP plasticity to memory formation and retrieval in the CA3 the exact molecular mechanisms underlying MF LTP have not been uncovered. The premise of this research builds upon our finding that there are at least two downstream cAMP effectors, PKA (protein kinase A) and Epac2 (exchange protein directly activated by cAMP 2), that contribute to cAMP dependent MF LTP. Despite these findings it is still not known how signaling by each of these effectors results in elevated release from MF synapses and, what are the important targets and substrates that are involved in MF LTP. Here we will use a comprehensive approach with leading edge proteomic, biochemical and electrophysiological approaches to determine the signaling partners of the cAMP effectors, and uncover the physiological mechanism of their actions. Thus, in Aim 1 we will take orthogonal approaches to find the interactors and substrates of PKA and Epac2 and validate and verify these by performing high resolution labeling in situ. In Aim 2 we will determine the exact physiological mechanism that underlie increases in release of neurotransmitter at MF synapses using a combined optogenetic-knockout/pharmacological strategy. In the final Aim we will answer the question of how these different but convergent mechanisms are engaged during naturalistic activity patterns, and whether selective disruption of these effectors impairs the ability of mice to separate similar patterns that underlie the formation and retrieval of episodic memories.