CaMKII Holoenzyme Mechanisms in Opposing Forms of Synaptic Plasticity

项目摘要/摘要 刺激海马NMDA型谷氨酸受体(NMDAR)可诱导长时程增强 (LTP)或抑郁症(LTD)，两种截然相反的突触可塑性形式，被认为是更高 大脑功能，如学习、记忆和认知。本提案将重点放在分子计算上。 这就调停了这两种形式的可塑性之间的决定。LTP长期以来一直被认为需要 钙/钙调蛋白依赖的蛋白激酶II(CaMKII)及其在T286的自动磷酸化(PT286)， 产生不依赖于钙离子的“自主”CaMKII活性(约为最大钙/钙调素刺激的20% 活动)。在本提案的第一个资助期，我们已经证明了CaMKII和pT286是额外的 有限公司需要。但是pT286CaMKII如何可能同时调节这两种截然相反的可塑性呢？ 我们已经在第二个资助期开始解决这个问题：LTP还需要CaMKII 与NMDA型谷氨酸受体(NMDAR)亚单位GluN2B的结合和两种机制被抑制 此绑定在LTD期间。相比之下，LTD需要明显的额外自动磷酸化，即 抑制pT305/306，阻断钙/CaM结合，进一步限制pT286，也直接抑制GluN2B 有约束力的。三种调节CaMKII的机制(pT286、pT305/306和GluN2B结合)都被认为是 需要CaMKII的全酶结构和所有的相互交叉调节。为了阐明这种交叉是如何- 监管工作使LTP对有限公司的决定由CaMKII，我们将在这里确定特定的全酶 每种机制背后的规则。在三个相关但独立的目标中，该项目将确定 CaMKII在T286处的磷酸化、T305/306处的磷酸化以及GluN2B相互作用的全酶规则。 第四个目标将测试对神经元功能的影响，预计LTP和LTD的效果会有所不同。

Project Summary/Abstract Stimulation of hippocampal NMDA-type glutamate receptors (NMDARs) can induce long-term potentiation (LTP) or depression (LTD), two opposing forms of synaptic plasticity that are thought to be required for higher brain functions such as learning, memory and cognition. This proposal will focus on the molecular computation that mediates the decision between these two forms of plasticity. LTP has long been known to require the Ca2+/calmodulin(CaM)-dependent protein kinase II (CaMKII) and its autophosphorylation at T286 (pT286), which generates Ca2+-independent “autonomous” CaMKII activity (~20% of the maximal Ca2+/CaM-stimulated activity). In the first funding period of this proposal, we have shown that CaMKII and pT286 are additionally required for LTD. But how can pT286 CaMKII possibly mediate both of these two opposing forms of plasticity? We have started to address this question in the second funding period: LTP additionally requires CaMKII binding to the NMDA-type glutamate receptor (NMDAR) subunit GluN2B, and two mechanisms suppressed this binding during LTD. By contrast, LTD instead requires a distinct additional autophosphorylation, the inhibitory pT305/306, which blocks Ca2+/CaM binding, limits further pT286, and also directly inhibits GluN2B binding. The three regulatory CaMKII mechanisms (pT286, pT305/306, and GluN2B binding) are all thought to require the CaMKII holoenzyme structure and all cross-regulate each other. In order to elucidate how this cross- regulation works to enable the LTP vs LTD decision by CaMKII, we will here determine the specific holoenzyme rules underlying each mechanism. In three related but independent aims, the project will determine the holoenzyme rules for CaMKII phosphorylation at T286, phosphorylation at T305/306, and GluN2B interaction. A fourth aim will test effects on neuronal functions, which are expected to differ for LTP versus LTD.