A-beta/APP signaling impairs CaMKII-dependent synaptic plasticity after ischemic brain injury

A-beta/APP 信号传导损害缺血性脑损伤后 CaMKII 依赖性突触可塑性

• 批准号: 10312704
• 负责人: Olivia Ruth Asfaha
• 金额: $ 4.02万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2021-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10312704
• 关键词: Acute; Alzheimer' s Disease; Alzheimer' s disease pathology; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Binding; Biochemistry; Brain Diseases; Ca(2+)-Calmodulin Dependent Protein Kinase; Cardiopulmonary Resuscitation; Cause of Death; Cell Death; Cells; Cerebral Ischemia; Chemicals; Chronic; Cleaved cell; Clinical Research; Cognitive deficits; Confocal Microscopy; DLG4 gene; Drug Targeting; Electrophysiology (science); Excitatory Synapse; Heart Arrest; Hippocampus (Brain); Hour; Human; Image; Impaired cognition; Impairment; Inhibitory Synapse; Intrabody; Ischemia; Ischemic Brain Injury; Knock-out; Knockout Mice; Label; Lead; Learning; Long-Term Potentiation; Measures; Mediating; Mediator of activation protein; Memory; Memory impairment; Modeling; Monitor; Mus; N-Methylaspartate; Neurons; Pathologic; Pathology; Pathway interactions; Physiological; Protein Precursors; Proteins; Proteolysis; Publishing; Research; Resistance; Resuscitation; Risk Factors; Role; Signal Pathway; Signal Transduction; Signaling Protein; Slice; Synapses; Synaptic plasticity; Techniques; Testing; Therapeutic; Time; Wild Type Mouse; Work; calmodulin-dependent protein kinase II; design; effective therapy; excitotoxicity; experimental study; gephyrin; improved; in vivo Model; inhibitor/antagonist; insight; long term memory; nervous system disorder; neuron loss; oAβ; prevent; protein expression; receptor; recruit

Project Summary Long-term potentiation (LTP) and other forms of synaptic plasticity are cellular correlates of learning and memory. The Ca2+/CaM-dependent protein kinase II (CaMKII) facilitates LTP by translocating to stimulated synapses and phosphorylating local targets. LTP is impaired in global cerebral ischemia (GCI) and Alzheimer’s disease (AD), two neurological disorders that demand effective treatment. GCI has acute and chronic effects: initially, it triggers excitotoxic neuronal cell death; long-term, it impairs LTP within the surviving neurons. Together, the neuronal loss and compromised synaptic plasticity underlie cognitive decline observed after ischemia, and an ideal therapy would target both. My proposed research aims to determine whether GCI-induced LTP impairments utilize signaling pathways previously implicated in AD. The amyloid-β precursor protein (APP) is proteolytically cleaved to form amyloid-β peptide1-42 (Aβ). Exogenous application of Aβ impairs LTP and CaMKII synaptic enrichment in hippocampal neurons. How does Aβ signal to disrupt CaMKII? Recent published work suggests that APP acts not only upstream of Aβ (as the Aβ precursor) but also downstream (as the Aβ receptor): Aβ association with APP was found to be required for LTP and memory impairments, as APP knockout (KO) prevented exogenous Aβ-induced deficits. While increased APP and Aβ are well-studied in AD pathology, a potential function for Aβ/APP signaling in ischemia has not been fully elucidated. Studies from our lab indicate that GCI- and Aβ-induced reductions in LTP utilize a common mechanism through CaMKII. To test the hypothesis that APP mediates the GCI-induced LTP impairment by disrupting CaMKII signaling, I will test three specific aims: i) whether APP mediates Aβ-induced impairments in LTP and CaMKII synaptic translocation, ii) APP mediates GCI-induced LTP impairments, and iii) whether the therapeutic window for protecting synaptic plasticity after GCI shows an extended range (days), even if the window for protecting neuronal cell death is much shorter (hours). This project will utilize acute hippocampal slices and cultures hippocampal neurons for biochemistry, slice electrophysiology, and live confocal microscopy. Imaging will employ FingR intrabodies that are designed to label endogenous proteins, including CaMKIIα and post-synaptic markers. The mouse in vivo model of global cerebral ischemia (GCI) closely mimics the most prevalent human condition (cardiac arrest). These optimized approaches will allow me to investigate whether potential cross-talk between APP/Aβ and CaMKII underlies impaired LTP following ischemic brain injury. Results from this project will improve our understanding of neurological disorders that utilize Aβ/APP-dependent mechanisms to impair synaptic plasticity.

项目摘要 长时程增强（LTP）和其他形式的突触可塑性是学习和记忆的细胞相关物 记忆Ca 2 +/CaM依赖性蛋白激酶II（CaMKII）通过转运到刺激的LTP来促进LTP。 突触和磷酸化局部目标。LTP在全脑缺血（GCI）和阿尔茨海默病中受损 AD是两种需要有效治疗的神经系统疾病。GCI具有急性和慢性影响： 最初，它触发兴奋毒性神经元细胞死亡;长期，它损害存活神经元内的LTP。 总之，神经元损失和受损的突触可塑性是在注射后观察到的认知下降的基础。 理想的治疗方法是针对这两种疾病。我提出的研究旨在确定GCI诱导的 LTP损伤利用先前与AD有关的信号通路。 淀粉样β前体蛋白（APP）被蛋白水解裂解形成淀粉样β肽1 -42（Aβ）。 外源性Aβ损伤海马神经元LTP和CaMK Ⅱ突触富集如何 Aβ信号破坏CaMKII？最近发表的研究表明，APP不仅作用于Aβ的上游（如Aβ 前体）以及下游（作为Aβ受体）：发现Aβ与APP的结合是LTP所需的 和记忆障碍，因为APP敲除（KO）阻止了外源性Aβ诱导的缺陷。虽然增加了 APP和Aβ在AD病理学中得到了充分的研究，但Aβ/APP信号在缺血中的潜在功能还没有得到充分的研究。 充分阐明。我们实验室的研究表明，GCI和Aβ诱导的LTP降低利用了一个共同的机制， 通过CaMKII机制。为了验证APP介导GCI诱导的LTP损伤的假设， 干扰CaMKII信号传导，我将测试三个特定的目标：i）APP是否介导Aβ诱导的损伤， LTP和CaMK II突触易位，ii）APP介导GCI诱导的LTP损伤，以及iii） GCI后保护突触可塑性的治疗窗口显示出延长的范围（天），即使 保护神经元细胞死亡的时间窗短得多（小时）。本项目将利用急性海马 切片和培养海马神经元用于生物化学、切片电生理学和活体共聚焦显微镜。 成像将采用FingR胞内抗体，其设计用于标记内源性蛋白质，包括CaMKIIα和 突触后标记小鼠全脑缺血（GCI）的体内模型非常接近于模拟大多数 普遍的人类状况（心脏骤停）。这些优化的方法将使我能够调查是否 APP/Aβ和CaMK Ⅱ之间的潜在相互作用是缺血性脑损伤后LTP受损的基础。结果 从这个项目将提高我们对利用Aβ/APP依赖的神经系统疾病的理解， 损害突触可塑性的机制。