SIRT1 Limits Microglial Toxicity in Alzheimer's Disease

SIRT1 限制阿尔茨海默病中的小胶质细胞毒性

• 批准号: 8661661
• 负责人: Li Gan
• 金额: $ 40.78万
• 依托单位: J. DAVID GLADSTONE INSTITUTES
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8661661
• 关键词: Abbreviations; Acetylation; Affect; Age; Alzheimer' s Disease; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Behavioral; Brain; CSF1 gene; Commit; Dependovirus; Disease; Event; Excision; Family; Foundations; Genes; Goals; Granulocyte-Macrophage Colony-Stimulating Factor; Histone Deacetylation; Histones; Human; Immune; Inflammatory; Inflammatory Response; Injection of therapeutic agent; Interleukins; Lipopolysaccharides; Long-Term Potentiation; Longevity; Macrophage Colony-Stimulating Factor; Mediating; Mediator of activation protein; Microglia; Modeling; Molecular; Muramidase; Mus; Myelogenous; Myeloid Cells; NF-kappa B; Nerve Degeneration; Neurons; Pathogenesis; Pathway interactions; Phenotype; Phosphorylation; Phosphotransferases; Play; Role; Signal Transduction; Stimulus; Subfamily lentivirinae; Synaptophysin; Terminator Codon; Testing; Toxic effect; Tumor Cell Line; Viral Vector; abeta accumulation; astrogliosis; base; bone; calbindin; cell type; chromatin immunoprecipitation; cytokine; dentate gyrus; enhanced green fluorescent protein; feeding; immunoreactivity; inhibitor/antagonist; injured; insight; macrophage; member; memory retention; morris water maze; mutant; neuroprotection; novel therapeutic intervention; novel therapeutics; overexpression; progenitor; promoter; research study; response; synaptic function; tau Proteins

DESCRIPTION (provided by applicant): Microglial activation has long been proposed to contribute to the pathogenesis of Alzheimer's disease (AD). Besides causing direct toxic effects on neuronal and synaptic functions, accumulation of amyloid beta (A¿) and/or tau stimulates microglial activation and expression of inflammatory cytokines, which can induce further neuronal damage. Blocking the toxic pathway in microglial activation could effectively protect against neurodegeneration. However, the molecular mechanisms modulating the microglial loop remain elusive. Our previous studies in primary cortical cultures suggest that NF-?B activation in microglia plays a critical role in microglial-mediated A¿ toxicity. Inhibition of NF-?B by SIRT1, a member of the sirtuin family of histone deacetylases, protected against microglia toxicity in A¿-treated primary cultures. In AD brains, SIRT1 levels were markedly reduced. SIRT1 expression in cultured microglia was significantly diminished by A¿ treatment. Based on these findings, we hypothesize that SIRT1 reduction is a key event leading to microglial toxicity in AD and that microglial SIRT1 limits A¿-mediated neuronal deficits by suppressing NF-?B activation. To test this hypothesis, we propose three Specific Aims. In Aim 1, we will inactivate SIRT1 in microglia of mice expressing human amyloid precursor protein (hAPP) and systematically examine how microglial SIRT1 inactivation affects inflammatory responses and A¿-related neuronal/behavioral deficits. In Aim 2, to determine if microglial SIRT1 exerts neuroprotection by suppressing NF-?B activation, we will determine if constitutive activation of canonical NF-?B signaling in microglia of hAPP mice exacerbates the deficits in a manner similar to SIRT1 deletion. In complementary experiments, we will determine if inhibiting NF-?B signaling will ameliorate A¿-associated neuronal deficits by infusing a potent NF-?B inhibitor in the brain or injection of a viral vector that inhibits NF-?B in microglia. In Aim 3, to determine the mechanism by which microglial SIRT1 inhibits NF-?B, we will systematically examine if SIRT1 inhibits NF-?B by deacetylating RelA and/or by reducing RelA phosphorylation in myeloid cells. Using chromatin immunoprecipitation (ChIP) analyses, we will then determine if SIRT1- induced suppression of NF-?B activation involves deacetylation of histones (H3K56Ac) in myeloid cells. Completion of the proposed studies will provide new insight into the molecular mechanisms modulating the microglial loop in neurodegeneration. These studies will also lay the foundation for our long-term goal of developing SIRT1-enhancing strategies as a new therapeutic approach for AD.

描述（由申请人提供）：长期以来，小胶质细胞激活一直被认为有助于阿尔茨海默氏病（AD）的发病机制，除了对神经元和突触功能产生直接毒性作用外，淀粉样蛋白β（A¿）和/或tau蛋白的积累还会刺激小胶质细胞。炎症细胞因子的激活和表达，可以诱导进一步的神经元损伤，阻断小胶质细胞激活的毒性途径可以有效防止神经退行性变。我们之前对原代皮质培养物的研究表明，小胶质细胞中的 NF-κB 激活在小胶质细胞介导的 A¿ SIRT1（组蛋白脱乙酰酶的 Sirtuin 家族成员）对 NF-κB 的抑制作用可防止 A¿ 中的小胶质细胞毒性。在 AD 大脑中，经 A 处理后，培养的小胶质细胞中 SIRT1 的表达显着降低。基于这些发现，我们发现 SIRT1 减少是导致 AD 中小胶质细胞毒性的关键事件，并且小胶质细胞 SIRT1 限制了 A¿为了检验这一假设，我们提出了三个具体目标：在目标 1 中，我们将灭活表达人类淀粉样前体蛋白 (hAPP) 的小鼠小胶质细胞中的 SIRT1，并系统地研究小胶质细胞 SIRT1 灭活的机制。影响炎症反应和 A¿在目标 2 中，为了确定小胶质细胞 SIRT1 是否通过抑制 NF-κB 激活发挥神经保护作用，我们将确定 hAPP 小鼠小胶质细胞中典型 NF-κB 信号传导的组成性激活是否会以某种方式加剧缺陷。与 SIRT1 缺失类似，在补充实验中，我们将确定抑制 NF-κB 信号传导是否会改善 A¿通过在大脑中注入有效的 NF-κB 抑制剂或在小胶质细胞中注射抑制 NF-κB 的病毒载体来抑制相关的神经元缺陷。在目标 3 中，为了确定小胶质细胞 SIRT1 抑制 NF-κB 的机制。将使用染色质免疫沉淀系统地检查 SIRT1 是否通过脱乙酰化 RelA 和/或减少骨髓细胞中的 RelA 磷酸化来抑制 NF-κB。 (ChIP) 分析，然后我们将确定 SIRT1 诱导的 NF-κB 激活抑制是否涉及骨髓细胞中组蛋白 (H3K56Ac) 的脱乙酰化。完成拟议的研究将为调节神经变性中小胶质细胞环的分子机制提供新的见解。这些研究也将为我们开发 SIRT1 增强策略作为 AD 新治疗方法的长期目标奠定基础。