Structural and Catalytic Functions of CaMKII in Neurons

Ca 2 +/钙调蛋白依赖性蛋白激酶II（CaMKII）是学习和记忆形式所必需的。在 在脑中，CaMKII的表达水平与结构蛋白相似（占总蛋白的1-2%），其12聚体 全酶结构允许多个同时的蛋白质相互作用。然而，CaMKII的结构作用 或者它与其他蛋白质相互作用的功能，充其量也就是知之甚少。主要的兴奋性神经元- 哺乳动物脑中的递质谷氨酸诱导海马中两种类型的CaMK II易位 神经元：短暂刺激（0.5-2分钟）后到达突触后部位， 延长暴露时间（3-5分钟）。两种类型的易位都需要多价CaMKII全酶 结构（未发表的意见）。短暂的谷氨酸处理可以诱导突触可塑性的形式 被认为是学习和记忆的基础，而长期接触会导致兴奋性毒性，这是一种细胞模型， 缺血性细胞死亡这个提议的目的是检验我们的假设，即突触易位 需要与NMDA型谷氨酸受体亚单位NR 2B结合并参与突触可塑性， 而突触外簇的形成是由CaMKII自缔合介导的，并参与缺血性脑损伤。 细胞死亡阐明CaMKII靶向的机制和功能将有助于我们理解 突触原则的基础更高的大脑功能和行为，并提供新的治疗途径， 缺血性损伤我们将在以下目标中实现我们的目标（使用大鼠海马和皮层 培养作为神经元研究的主要模型系统）：（1）确定蛋白质相互作用所需的 神经元中的亚细胞CaMK II定位。我们将确定CaMKII突变和抑制剂， NR 2B结合或自缔合，并确定它们对神经元中GFP-CaMK II定位的影响。 (2)确定CaMKII活性、突触靶向和神经保护作用与神经毒性作用， 突触外群集我们将利用CaMKII活性的抑制剂和聚集，敲低 通过RNAi的表达，以及CaMKII野生型和突变体的过表达， 活动、监管和目标。 (3)确定CaMKII在调节突触数量和强度中的功能。我们将利用 与（2）中相同的工具，并在已建立的测定中确定对突触数量和强度的影响。

The Ca2+/calmodulin-dependent protein kinase II (CaMKII) is required for forms of learning and memory. In brain, CaMKII is expressed at levels reminiscent of structural proteins (1-2% of total protein), and its 12meric holoenzyme structure allows multiple simultaneous protein interactions. However, structural roles of CaMKII or functions of its interactions with other protein are understood poorly at best. The major excitatory neuro- transmitter in mammalian brain, glutamate, induces two types of CaMKII translocation in hippocampal neurons: To postsynaptic sites upon brief stimulation (0.5-2 min) and to extra-synaptic clusters after extended exposure (3-5 min). Both types of translocation require the multivalent CaMKII holoenzyme structure (unpublished observations). Brief glutamate treatment can induce forms of synaptic plasticity thought to underlie learning and memory, while extended exposure leads to excitotoxicity, a cellular model for ischemic cell death. The goal of this proposal is to test our hypotheses that synaptic translocation requires binding to the NMDA-type glutamate receptor subunit NR2B and is involved in synaptic plasticity, while formation of extrasynaptic clusters is mediated by CaMKII self-association and is involved in ischemic cell death. Elucidating the mechanisms and functions of CaMKII targeting will aid our understanding of synaptic principles underlying higher brain functions and behavior, and provide new therapeutic avenues for ischemic damage. We will accomplish our goal in the following aims (using rat hippocampal and cortical cultures as main model systems for studies in neurons): (1) Determine protein interactions required for subcellular CaMKII localization in neurons. We will identify CaMKII mutations and inhibitors that prevent NR2B-binding or self-association in vitro and determine their effect on GFP-CaMKII localization in neurons. (2) Determine neuroprotective versus neurotoxic effects of CaMKII activity, synaptic targeting, and extrasynaptic clustering. We will make use of an inhibitor of CaMKII activity and clustering, knockdown of expression by RNAi, and overexpressionof CaMKII wildtype and mutants with specific impairments in activity, regulation and targeting. (3) Determine functions of CaMKII in regulation of synapse number and strength. We will make use of the same tools as in (2) and determine effects on synapse number and strength in established assays.