CRCNS: Neural signals that maintain/refresh LTP and memory

CRCNS：维持/刷新 LTP 和记忆的神经信号

• 批准号: 9242345
• 负责人: Leslie C Griffith
• 金额: $ 36.4万
• 依托单位: BRANDEIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9242345
• 关键词: Achievement; Action Potentials; Acute; Addictive Behavior; Affect; Basal Ganglia; Behavioral; Biochemical; Catalytic Domain; Cells; Closure by clamp; Computer Simulation; DNA; Dendritic Spines; Dependence; Dominant-Negative Mutation; Drosophila genus; Ensure; Enzymes; Event; Fluorescence; Fluorescence Resonance Energy Transfer; Fractionation; Health; Hippocampus (Brain); Holoenzymes; In Vitro; Information Storage; Instruction; Label; Maintenance; Measures; Mediating; Memory; Memory Disorders; Methods; Modeling; Modification; Molecular; Molecular Weight; Mushroom Bodies; Neurons; Nobel Prize; Phosphorylation; Physiologic pulse; Potassium Channel; Preparation; Process; Property; Protein Subunits; Proteins; Rattus; Reaction; Rest; Role; SNAP receptor; Signal Transduction; Site; Slice; Stimulus; Stroke; Synapses; Testing; Theoretical model; Time; Transgenes; Ursidae Family; Work; addiction; dentate gyrus; experimental study; in vivo; interest; neurotransmission; overexpression; protein degradation; reaction rate; reconstitution; relating to nervous system

Experiments show that interference with CaMKI I after LTP can erase LTP, a strong indication of the importance of CaMKll in the LTP maintenance process. CaMKll holoenzymes contain 12 catalytic subunits. In the ON state, each subunit is phosphorylated and therefore active. When a site becomes dephosphorylated, it can be refreshed (rephosphorylated) by a neighboring active subunit. Aim 1. Is refresh dependent on activity? The CaMKll refresh process requires low levels of Ca, but whether achievement of this level is dependent on spontaneous neural activity is not known. Therefore, a fundamental question of interest is whether the maintenance of LTP or memory requires neural activity. In Aim 1A, we will test this in acute hippocampal slices. In Aim 1B, we will explore whether activity is necessary for maintaining memory at the behavioral level using Drosophila. Although it is known that CaMKll is important for Drosophila memory, experiments have not yet tested whether CaMKll is important in memory maintenance. Given the importance of this issue for interpreting the effects of activity on memory, we will conduct the critical erasure test for determining whether CaMKll mediates memory storage in Drosophila. Aim 2. Does CaMKll subunit exchange occur in vivo: a potential mechanism for molecular refresh? According to theoretical models, switch stability could long outlive the lifetime of any subunit if CaMKll underwent protein turnover by subunit exchange: a newly inserted unphosphorylated subunit could be phosphorylated by a neighboring phosphorylated subunit, thereby providing a molecular refresh. We will make the first attempts to test whether subunit exchange occurs in living cells (Drosophila and hippocampus) and characterize its activity-dependence. Aim 3. Computational modelling: what kinds of neural activity are required to refresh CaMKll phosphorylation? The level of resting Ca2+, and that during spontaneous action potentials or mEPSPs can be estimate, as well as the rate of these reactions. We will use a verified computational model of CaMKll to determine whether these brief Ca2+ events are sufficient to refresh the phosphorylated state of CaMKll and thus ensure the stability of stored information. The results will bear importantly on the fundamental question of whether refresh reactions are mediated by spontaneous activity, or alternatively, are dependent on a network process that replays memories. RELEVANCE (See instructions): Understanding the processes that store memory at synapses will have major implications for several health problems. In particular, addiction has been demonstrated to involve persistent changes in CaMKll at synapses in the basal ganglia networks that are critical for addictive behaviors. The proposed work may provide ways to turn off CaMKll and thus reduce addictive behaviors. CaMKll has also been strongly implicated in memory disorders and stroke.

实验表明，在LTP后干扰CaMKI I可以消除LTP，这是LTP的一个强有力的指示。 CaMKII在LTP维持过程中的重要性。CaMKII全酶含有12个催化亚基。 在ON状态下，每个亚基都被磷酸化，因此具有活性。当一个网站成为 在去磷酸化后，它可以被邻近的活性亚基更新（再磷酸化）。 目标1。刷新是否依赖于活动？CaMKll刷新过程需要低水平的Ca，但是 这个水平的达到是否依赖于自发神经活动尚不清楚。因此 最基本的问题是LTP或记忆的维持是否需要神经活动。在 目标1A，我们将在急性海马切片中测试这一点。在目标1B中，我们将探讨活动是否必要 使用果蝇在行为层面维持记忆。尽管已知CaMKll是 虽然CaMKII对果蝇的记忆很重要，但实验还没有测试CaMKII是否在记忆中很重要 上维护考虑到这个问题对于解释活动对记忆的影响的重要性，我们将 进行临界擦除测试以确定CaMKII是否介导果蝇中的记忆储存。 目标二。CaMKll亚基交换是否发生在体内：分子更新的潜在机制？ 根据理论模型，如果CaMKll 1与CaMKll 1结合，则开关稳定性可以比任何亚基的寿命更长。 通过亚基交换进行蛋白质周转：一个新插入的未磷酸化的亚基可以被 在一些实施方案中，所述蛋白质被邻近的磷酸化亚基磷酸化，从而提供分子更新。我们将 首次尝试测试亚基交换是否发生在活细胞（果蝇和海马）中 并描述其活性依赖性。 目标3.计算建模：刷新CaMKll需要什么样的神经活动 磷酸化？静息Ca2+水平和自发动作电位或mEPSP期间的Ca2+水平可以 以及这些反应的速率。我们将使用经验证的CaMKll计算模型来 确定这些短暂的Ca2+事件是否足以刷新CaMKII的磷酸化状态，以及 从而保证存储信息的稳定性。结果将对根本问题产生重要影响 刷新反应是否由自发活动介导，或者取决于 一种网络进程，可以重放记忆。 相关性（参见说明）： 了解突触存储记忆的过程将对几个健康问题产生重大影响。 问题特别地，已经证明成瘾涉及CaMK11的持续变化， 基底神经节网络中的突触对成瘾行为至关重要。拟议的工作可能 提供关闭CaMKII的方法，从而减少成瘾行为。CaMKll也强烈地 与记忆障碍和中风有关