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: 8517531
• 负责人: Li Gan
• 金额: $ 38.54万
• 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/8517531
• 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（由适用提供）：长期以来一直提出小胶质细胞激活为阿尔茨海默氏病（AD）的发病机理做出贡献。除了引起对神经元和突触功能的直接毒性作用外，淀粉样蛋白β（a¿）和/或tau的积累还刺激了炎性细胞因子的小胶质细胞激活和表达，这可以诱导进一步的神经元损伤。阻断小胶质细胞激活中的有毒途径可以有效地防止神经变性。但是，调节小胶质环的分子机制仍然难以捉摸。我们先前在原发性皮质培养物中的研究表明，小胶质细胞中的NF-？B激活在小胶质细胞介导的A毒性中起关键作用。 SIRT1的抑制NF-？B，这是组蛋白脱乙酰基酶的一家成员，可保护ATHETACETACE的原代培养物中的小胶质细胞毒性。在AD大脑中，SIRT1水平明显降低。通过A处理，SIRT1在培养的小胶质细胞中的表达显着降低。基于这些发现，我们假设SIRT1还原是导致AD小胶质毒性的关键事件，而小胶质细胞SIRT1限制了介导的神经元来定义NF-？b激活来定义。为了检验这一假设，我们提出了三个具体目标。在AIM 1中，我们将在表达人淀粉样蛋白前体蛋白的小鼠的小胶质细胞中灭活SIRT1，并系统地检查小胶质细胞SIRT1失活如何影响炎症反应并与A e e e nequ相关的神经元/行为缺陷。在AIM 2中，为了确定小胶质细胞SIRT1是否通过抑制NF-？b激活来施加神经保护作用，我们将确定Happ小鼠的小胶质细胞的构型NF-？B信号是否会以类似于SIRT1 DETION的方式加剧缺陷。在完整的实验中，我们将确定抑制NF-？B信号传导是否会通过在大脑中注入潜在的NF-抑制剂或注射病毒载体来改善A a a bess的神经元来定义，或者在小胶质细胞中抑制NF-？b。在AIM 3中，为了确定小胶质细胞SIRT1抑制NF-？B的机制，我们将系统地检查SIRT1是否通过脱乙酰化rela和/或通过减少髓样细胞中的Rela磷酸化来抑制NF-？B。然后，使用染色质免疫沉淀（CHIP）分析，我们将确定SIRT1诱导的NF-？B活化抑制是否涉及髓样细胞中组蛋白（H3K56AC）的脱乙酰基化。拟议研究的完成将为调节神经变性小胶质环的分子机制提供新的见解。这些研究还将为我们的长期目标奠定基础，即开发SIRT1增强策略作为AD的新治疗方法。