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

基本信息

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
项目类别：
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&apos s Disease Alzheimer&apos 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

项目摘要

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.

项目概要长时程增强（LTP）和其他形式的突触可塑性是学习和能力的细胞相关性。 Ca2+/CaM 依赖性蛋白激酶 II (CaMKII) 通过易位到刺激来促进 LTP。突触和磷酸化局部靶标在全脑缺血 (GCI) 和阿尔茨海默病中受损。疾病（AD），两种需要有效治疗的神经系统疾病，具有急性和慢性影响：最初，它会引发兴奋性神经细胞死亡；从长远来看，它会损害存活神经元内的 LTP。总之，神经元损失和突触可塑性受损是观察到的认知能力下降的原因我提出的研究旨在确定 GCI 是否会引起缺血。 LTP 损伤利用了先前与 AD 相关的信号通路。淀粉样蛋白-β 前体蛋白 (APP) 通过蛋白水解裂解形成淀粉样蛋白-β 肽 1-42 (Aβ)。外源性应用 Aβ 会损害海马神经元中的 LTP 和 CaMKII 突触富集。 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（作为 Aβ）前体）而且下游（作为 Aβ 受体）：Aβ 与 APP 的关联被发现是 LTP 所必需的和记忆障碍，因为 APP 敲除 (KO) 可以防止外源性 Aβ 诱导的缺陷，同时增加。 APP 和 Aβ 在 AD 病理学中已得到充分研究，但 Aβ/APP 信号传导在缺血中的潜在功能尚未被研究。我们实验室的研究表明，GCI 和 Aβ 诱导的 LTP 减少利用了一个共同点。验证 APP 通过 CaMKII 介导 GCI 诱导的 LTP 损伤的假设。破坏 CaMKII 信号传导，我将测试三个具体目标：i) APP 是否介导 Aβ 诱导的损伤 LTP 和 CaMKII 突触易位，ii) APP 介导 GCI 诱导的 LTP 损伤，以及 iii) 是否 GCI 后保护突触可塑性的治疗窗显示出延长的范围（天），即使保护神经细胞死亡的窗口要短得多（数小时），该项目将利用急性海马。对海马神经元进行切片和培养，用于生物化学、切片电生理学和实时共聚焦显微镜。成像将采用 FingR 胞内抗体，旨在标记内源蛋白，包括 CaMKIIα 和小鼠全脑缺血（GCI）体内模型与突触后标记最接近。这些优化的方法将使我能够调查是否存在普遍的人类状况（心脏骤停）。 APP/Aβ 和 CaMKII 之间的潜在串扰是缺血性脑损伤后 LTP 受损的基础。该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。