Suppression of CaMKII synaptic targeting and beta-amyloid pathology

项目总结： 海马突触可塑性的机制，特别是长时程增强(LTP)和 突触强度的抑制被认为是学习、记忆和认知的基础。这些函数 在阿尔茨海默病(AD)患者、AD小鼠模型和急性海马片中被破坏 用β-淀粉样蛋白(Aβ，AD的主要神经病理因子)治疗后，显示出严重的长时程增强损伤。LTP 需要钙/钙调蛋白依赖的蛋白激酶IIα(CaMKIIα)及其与突触的调节结合 NMDA型谷氨酸受体(NMDAR)，导致兴奋性突触快速积聚CaMKIIα。 我的初步发现表明，这种CaMKIIα突触靶向被急性应用Aβ抑制 需要CaMKIIα活性的剂量和时间依赖方式。这种对CaMKIIα靶向的抑制 暗示了CaMKIIα/NMDAR相互作用的潜在中断。我们实验室的研究表明 CaMKIIα/NMDAR结合可以通过两种不同的机制来抑制：CaMKIIαT305/306自动- 磷酸化(pT305/306)和死亡相关蛋白激酶1(DAPK1)的激活。我的初选 我们实验室的结果和最近发表的研究结果表明，CaMKIIαpT305/306和DAPK1激活 抑制LTD期间兴奋性突触中CaMKIIα的积聚，使其成为潜在的 介导Aβ在长时程增强过程中对CaMKIIα靶向的干扰随着CaMKII运动到兴奋性 突触是正常长时程增强所必需的，它的抑制为Aβ诱导的突触提供了一种机制 LTP受损。因此，我的建议将调查Aβ导致长时程增强损伤的假设 是通过抑制针对兴奋性突触的CaMKIIα，即CaMKIIα介导的 PT305/306和/或DAPK1激活。具体地说，我将利用药物抑制和突变小鼠品系 确定这些机制是否介导了Aβ诱导的针对兴奋性的CaMKIIα的抑制 突触和/或Aβ引起的长时程增强损伤。值得注意的是，该项目使用内部机构来监控 可塑性过程中针对兴奋性和抑制性突触的内源性CaMKIIα。这一创新战略 允许同时对活细胞中的多种内源性蛋白质进行成像，而不会影响基底 定位或细胞功能。这个提议的结果将提供对细胞和分子的洞察 β诱导的突触可塑性障碍的潜在机制，并可能有助于我们的 了解阿尔茨海默病相关的记忆和认知障碍。

PROJECT SUMMARY: Mechanisms underlying hippocampal synaptic plasticity, specifically long-term potentiation (LTP) and depression (LTD) of synaptic strength, are thought to underlie learning, memory, and cognition. These functions are disrupted in patients with Alzheimer’s disease (AD), and AD mouse models and acute hippocampal slices treated with β-amyloid (Aβ, a major neuropathological agent in AD) exhibit severe LTP impairments. LTP requires the Ca2+/calmodulin(CaM)-dependent protein kinase II α (CaMKIIα) and its regulated binding to synaptic NMDA-type glutamate receptors (NMDAR), which results in rapid CaMKIIα accumulation at excitatory synapses. My preliminary findings indicate that this CaMKIIα synaptic targeting is suppressed by acute Aβ application in a dose- and time-dependent manner that requires CaMKIIα activity. This suppression of CaMKIIα targeting suggests a potential disruption in the CaMKIIα/NMDAR interaction. Studies from our lab demonstrate that CaMKIIα/NMDAR binding can be suppressed by two distinct mechanisms: CaMKIIα T305/306 auto- phosphorylation (pT305/306) and activation of death associated protein kinase 1 (DAPK1). My preliminary results and recent published findings from our lab indicate that CaMKIIα pT305/306 and DAPK1 activation suppress CaMKIIα accumulation at excitatory synapses during LTD, making them potential candidates for mediating the Aβ-induced disruption in CaMKIIα targeting during LTP. As CaMKII movement to excitatory synapses is required for normal LTP, its suppression provides a mechanism for the well-described Aβ-induced impairment of LTP. Therefore, my proposal will investigate the hypothesis that the Aβ-induced LTP impairment is mediated by mechanisms that suppress CaMKIIα targeting to excitatory synapses, namely CaMKIIα pT305/306 and/or DAPK1 activation. Specifically, I will utilize pharmacological inhibition and mutant mouse lines to determine whether these mechanisms mediate the Aβ-induced suppression of CaMKIIα targeting to excitatory synapses and/or the Aβ-induced LTP impairment. Notably, this project employs the use of intrabodies to monitor endogenous CaMKIIα targeting to excitatory and inhibitory synapses during plasticity. This innovative strategy allows for the simultaneous imaging of multiple endogenous proteins in living cells, without impacting basal localization or cellular function. The results of this proposal will provide insight into the cellular and molecular mechanisms underlying Aβ-induced malfunctions in synaptic plasticity, and potentially contribute to our understanding of AD-related memory and cognitive impairments.