CaMKII and Neuronal Excitability Changes in Learning

CaMKII 和学习中神经元兴奋性的变化

• 批准号: 6570148
• 负责人: MASUO OHNO
• 金额: $ 30.04万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-12-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6570148
• 关键词: association learning; biological signal transduction; brain electrical activity; calmodulin dependent protein kinase; electromyography; enzyme activity; enzyme mechanism; genetically modified animals; hippocampus; laboratory mouse; learning; memory; muscarinic receptor; neural plasticity; neural transmission; pharmacogenetics; phosphorylation; point mutation; polymerase chain reaction; potassium channel; pyramidal cells; voltage /patch clamp; western blottings

DESCRIPTION (provided by applicant): The goal of the proposed experiments is to understand the functional role of calcium/calmodulin-dependent protein kinase II (CaMKII) in regulating learning-associated changes in excitability of hippocampal neurons. It is well established that CaMKII is a key molecule required for learning and memory. Previous genetic and pharmacological studies have provided evidence for CaMKII-dependent modifications of synaptic strength during learning, although little is known about its role in the modulation of neuronal excitability, another important cellular mechanism of learning and memory. Neuronal excitability is primarily determined by the properties of ion channels: K+-channels, in particular, are key components in tuning of the membrane excitability of neurons. The working hypothesis to be tested is that CaMKII not only controls hippocampal synaptic plasticity but also modulates K+-channel properties accounting for an increase in hippocampal neuronal excitability during learning and memory consolidation. Analysis of alphaCaMKII mutant mice will determine the role of CaMKII as a molecular constituent responsible for learning-related excitability changes. The mutant mouse we will use is one that carries a point mutation at an autophosphorylation site in the alphaCaMKII gene (T286A) and consequently loses the function of this kinase. This study will clarify the role of alphaCaMKII in the increase in excitability of CA1 pyramidal neurons as evidenced by reduced afterhyperpolarization (AHP) during the acquisition of hippocampus-dependent associative learning (trace eyeblink conditioning) and spatial learning (water maze) tasks. Whole cell voltage-clamp recording will determine which components of outward potassium currents (SlAHP,IAHP, IM, IC, IA or IH) play a critical role in alphaCaMKII -mediated regulation of CA1 neuron excitability during hippocampal learning. Our integrated analyses of alphaCaMKII T2sBA mutants with behavioral, biophysical, biochemical and pharmacogenetic approaches will evaluate a molecular mechanism by which alphaCaMKII -mediated phosphorylation of K-channel subunits following muscarinic neurotransmission could contribute to hippocampal learning processes by regulating neuronal excitability. Further understanding of how CaMKII functions to establish learning and memory in brain will have relevance to the better understanding of mechanisms underlying learning deficits or dementia, and to developing novel strategies to treat learning disorders.

描述（由申请人提供）：拟定实验的目的是了解钙/钙调蛋白依赖性蛋白激酶II（CaMKII）在调节海马神经元兴奋性的学习相关变化中的功能作用。众所周知，CaMKII是学习和记忆所需的关键分子。以前的遗传和药理学研究提供了证据，在学习过程中的突触强度的CaMKII依赖性的修改，虽然很少有人知道它在神经元兴奋性的调制，学习和记忆的另一个重要的细胞机制的作用。神经元兴奋性主要由离子通道的性质决定：特别是K+通道，是调节神经元膜兴奋性的关键组分。待检验的工作假设是，CaMKII不仅控制海马突触可塑性，而且还调节K+通道特性，从而在学习和记忆巩固过程中增加海马神经元的兴奋性。对alphaCaMKII突变小鼠的分析将确定CaMKII作为负责学习相关兴奋性变化的分子成分的作用。我们将使用的突变小鼠是在alphaCaMKII基因（T286 A）中的自磷酸化位点携带点突变并因此失去该激酶功能的小鼠。本研究将阐明α CaMKII在CA 1锥体神经元兴奋性增加中的作用，这一点可以通过在获得视皮层依赖性联想学习（跟踪眨眼条件反射）和空间学习（水迷宫）任务期间降低后超极化（AHP）来证明。全细胞电压钳记录将确定外向钾电流的哪些组分（SlAHP、IAHP、IM、IC、IA或IH）在海马学习期间α CaMK II介导的CA 1神经元兴奋性调节中起关键作用。我们的综合分析的alphaCaMKII T2 sBA突变体的行为，生物物理，生物化学和药物遗传学的方法将评估的分子机制，alphaCaMKII介导的磷酸化的K-通道亚基的毒蕈碱神经传递后，可以有助于海马学习过程中通过调节神经元的兴奋性。进一步了解CaMKII如何在大脑中建立学习和记忆功能，将有助于更好地理解学习障碍或痴呆的潜在机制，并开发治疗学习障碍的新策略。