Mechanism of CREB dysregulation in Alzheimer brain

阿尔茨海默病大脑 CREB ​​失调的机制

• 批准号: 8544701
• 负责人: SUBBIAH PUGAZHENTHI
• 金额: --
• 依托单位: VA EASTERN COLORADO HEALTH CARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8544701
• 关键词: A Mouse; Adverse effects; Affect; Age-Years; Alzheimer' s Disease; Alzheimer' s disease risk; Anti-Inflammatory Agents; Astrocytes; Astrocytosis; BCL2 gene; Brain; Brain-Derived Neurotrophic Factor; Cells; ChIP-seq; Chronic; Clinical Trials; Coculture Techniques; Cognition; Complex; Conditioned Culture Media; Cyclic AMP-Responsive DNA-Binding Protein; Data; Deterioration; Disease; Distress; Down-Regulation; E1A-associated p300 protein; Elderly; Emetics; Environment; Epidemiologic Studies; Event; Free Radicals; Functional disorder; Gene Chips; Gene Expression; Gene Expression Profile; Gene Expression Profiling; Gene Transfer; Genes; Genetic Transcription; Growth Factor; Healthcare Systems; Hippocampus (Brain); Human; Impaired cognition; In Vitro; Inflammation; Inflammation Mediators; Inflammatory; Inflammatory Response; JUN gene; Link; Mediating; Medical center; Memory; Methodology; Microglia; Minocycline; Modeling; Molecular; Mus; NF-kappa B; Nerve Degeneration; Neurons; Neurotoxins; Non-Steroidal Anti-Inflammatory Agents; Nuclear; Oxidative Stress; Pathology; Pathway interactions; Patients; Pharmaceutical Preparations; Phosphorylation; Play; Population; Protein Family; Proteins; Protocols documentation; Reactive Oxygen Species; Role; Rolipram; Sampling; Signal Pathway; Signal Transduction; Signaling Pathway Gene; Site; Synapses; Testing; Therapeutic; Therapeutic Intervention; Transgenic Mice; Transgenic Organisms; Veterans; analog; base; cell type; cognitive function; cytokine; design; experience; in vivo; injured; laser capture microdissection; macrophage; mouse model; neurofibrillary tangle formation; neuroinflammation; neuronal survival; neurotoxic; novel; pathogen; progressive neurodegeneration; promoter; protein expression; protein function; public health relevance; response; restoration; spatial relationship; synergism; transcription factor

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is characterized by cognitive dysfunction and progressive neurodegeneration. Hallmarks of AD pathology include accumulation of A¿-containing plaques, formation of neurofibrillary tangles and synaptic dysfunction. Microglia, the resident macrophages of the brain, play a protective role by reducing A¿ load. However, cytokines and free radicals released from hyperactivated microglia cause neuronal damage. Injured neurons facilitate their own demise by sending out distress signals to microglia. This proposal takes a close look at the molecular events in neurons exposed to activated microglia by in vitro and in vivo studies. Altered signaling pathways and orchestrated gene expression patterns in neurons are known to play significant roles in causing AD pathology. In this model, transcription factors provide a crucial link between signaling pathways and gene expression. Cyclic AMP response element binding protein (CREB), a nuclear transcription factor, enhances cognition, memory formation and neuronal survival. CREB is known to be downregulated in the AD brain. However, therapeutically targeting CREB is a challenge because of its broad spectrum actions. Transcription factors are directed to appropriate promoters in a context and cell-type dependent manner by upstream signals. We have characterized the growth factor-stimulated signaling pathways that activate CREB and the mechanism through which oxidative stress interferes with CREB function in cultured neurons. In a recent study with AD post-mortem samples and Alzheimer's transgenic mice, we identified the decrease of hippocampal CREB expression by A¿-generated oxidative stress as a late event. But the decrease in CREB content is preceded by persistent downregulation of CREB function. The following two critical findings from our preliminary studies suggest that inflammation, an early event in the progression of AD, interferes with CREB function. (i) CREB-regulated BDNF expression in human neuroprogenitor cell (NPC)- derived neurons was decreased by conditioned medium from A¿-activated human microglia. (ii) Restoration of CREB function protected neurons cocultured with A¿-activated microglia. Protective and neurodegenerative pathways of inflammation can be delineated at the transcriptional level. Inflammation-mediated CREB dysregulation takes place at the following sites: (i) Cytokines and reactive oxygen species decrease CREB phosphorylation/activation. (ii) Inflammation activates c-jun, STAT-1 and NF-?B, the transcriptions factors that compete with CREB for the limited pool of coactivators, CBP and p300. (iii) Inflammation can direct CREB to pathways other than those needed for neuronal function. (iv) Proteins produced in response to inflammation functionally antagonize CREB target proteins that promote neuronal survival. Our hypothesis is that the pathogenic component of chronic neuroinflammation, acting synergistically with oxidative stress, downregulates CREB-mediated transcription of neuroprotective genes in the AD brain. This hypothesis will be tested in human neuroprogenitor cell derived-neurons, cocultured with microglia and in a triple transgenic Alzheimer's mice using novel methodologies including laser capture microdissection, network motif-based analysis and design-based stereology with the following Specific Aims: Aim 1. To determine the mechanism of CREB downregulation in cultured human neuroprogenitor cell-derived neurons exposed to A¿-activated microglia and astrocytes. Aim 2. To identify neuronal CREB downregulation as a pathogenic component of neuroinflammation in triple transgenic Alzheimer's (3XTg-AD) mouse brain: Therapeutic strategies can target transcription factors and their network for profound beneficial effects. Our lab has 15 years of experience and the expertise to examine CREB function in the context of parallel activation of competing transcription factors during inflammation and oxidative stress.

描述（由申请人提供）： 阿尔茨海默病（AD）的特征是认知功能障碍和进行性神经退行性变。AD病理学的标志包括含A？斑块的积累、神经元缠结的形成和突触功能障碍。小胶质细胞，大脑的常驻巨噬细胞，通过减少A？负荷发挥保护作用。然而，从过度活化的小胶质细胞释放的细胞因子和自由基引起神经元损伤。受伤的神经元通过向小胶质细胞发出求救信号来促进自身的死亡。该建议通过体外和体内研究密切关注暴露于活化小胶质细胞的神经元中的分子事件。 已知神经元中改变的信号传导途径和协调的基因表达模式在引起AD病理中起重要作用。在这个模型中，转录因子提供了信号通路和基因表达之间的关键联系。环磷酸腺苷反应元件结合蛋白（CREB）是一种核转录因子，可增强认知、记忆形成和神经元存活。已知CREB在AD脑中下调。然而，治疗靶向CREB是一个挑战，因为它的广谱作用。转录因子通过上游信号以上下文和细胞类型依赖性方式定向到合适的启动子。我们的特点是生长因子刺激的信号通路，激活CREB和机制，通过氧化应激干扰CREB功能在培养的神经元。在最近一项对AD死后样本和阿尔茨海默氏症转基因小鼠的研究中，我们确定了海马CREB表达的减少是由A产生的氧化应激引起的晚期事件。但CREB含量的下降是在CREB功能持续下调之前。我们的初步研究的以下两个关键发现表明，炎症是AD进展的早期事件，干扰CREB功能。(i)CREB调节的BDNF在人神经祖细胞（NPC）衍生的神经元中的表达被A？激活的人小胶质细胞的条件培养基降低。(ii)CREB功能的恢复保护了与A？激活的小胶质细胞共培养的神经元。 炎症的保护性和神经退行性途径可以在转录水平上描绘。炎症介导的CREB失调发生在以下位点：（i）细胞因子和活性氧物质降低CREB磷酸化/活化。(ii)炎症激活c-jun、STAT-1和NF-？B，与CREB竞争有限的共激活因子库CBP和p300的转录因子。(iii)炎症可以将CREB引导到神经元功能所需的通路以外的通路。(iv)炎症反应产生的蛋白质在功能上拮抗促进神经元存活的CREB靶蛋白。我们的假设是慢性神经炎症的致病成分与氧化应激协同作用，下调CREB介导的AD脑神经保护基因的转录。该假设将在与小胶质细胞共培养的人神经祖细胞衍生的神经元中以及在三重转基因阿尔茨海默氏症小鼠中使用新方法进行测试，所述新方法包括激光捕获显微切割、基于网络基序的分析和基于设计的体视学，具体目的如下：目的1。确定A？激活的小胶质细胞和星形胶质细胞对培养的人神经祖细胞源性神经元CREB下调的机制。 目标2.为了确定神经元CREB下调作为三重转基因阿尔茨海默氏症（3XTg-AD）小鼠脑中神经炎症的致病成分：治疗策略可以靶向转录因子及其网络，以产生深远的有益效果。我们的实验室拥有15年的经验和专业知识，可以在炎症和氧化应激期间并行激活竞争性转录因子的背景下检查CREB功能。