CaMKII and Neuronal Excitability Changes in Learning

描述（由申请人提供）：拟议实验的目的是了解钙/钙调素依赖性蛋白激酶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。先前的遗传和药理学研究已经为学习过程中突触强度的camkii依赖性改变提供了证据，尽管人们对其在神经元兴奋性调节中的作用知之甚少，神经元兴奋性是学习和记忆的另一个重要细胞机制。神经元的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成分。待测试的工作假设是，CaMKII不仅控制海马突触可塑性，还调节K+通道特性，导致学习和记忆巩固过程中海马神经元兴奋性的增加。对α CaMKII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alacamkii基因（T286A）的自磷酸化位点上携带点突变的小鼠，因此失去了该激酶的功能。本研究将阐明alphaCaMKII在CA1锥体神经元兴奋性增加中的作用，其证据是在海马体依赖性联想学习（瞬迹条件反射）和空间学习（水迷宫）任务的习得过程中，后超极化（AHP）减少。全细胞电压钳记录将确定向外钾电流的哪些组成部分（SlAHP，IAHP， IM， IC， IA或IH）在海马学习过程中由alphaCaMKII介导的CA1神经元兴奋性调节中发挥关键作用。我们通过行为学、生物物理学、生物化学和药物遗传学的方法对alphaCaMKII T2sBA突变体进行综合分析，以评估一种分子机制，通过这种机制，alphaCaMKII介导的k通道亚基在毒菌神经传递后的磷酸化可以通过调节神经元兴奋性来促进海马学习过程。进一步了解CaMKII如何在大脑中建立学习和记忆，将有助于更好地理解学习缺陷或痴呆的机制，并开发治疗学习障碍的新策略。

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.