Mechanism of Activation of Innate Immunity by ISS-DNA

ISS-DNA 激活先天免疫的机制

• 批准号: 6640821
• 负责人: Wen-Ming Chu
• 金额: $ 27.48万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-15 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6640821
• 关键词: bacterial DNA; biological signal transduction; immunoregulation; laboratory mouse; leukocyte activation /transformation; macrophage; microorganism immunology; protein kinase; toll like receptor

DESCRIPTION (provided by applicant): Innate immunity enables an organism to respond rapidly to invading microorganisms. To do this, innate immune system uses a variety of receptors or intracellular proteins that can recognize a microbial pathogen by the motifs pathogen-associated molecular patterns (PAMPs). Pathogen-associated motifs include mannans in the yeast cell wall, formylated peptides and various bacterial cell-wall components such as lipopolysaccharide (LPS), lipopeptides, peptidoglycans and teichoic acids. Bacterial DNA is also a potent inducer of innate immunity. Bacterial DNA contains increased frequency of CpG dinucleotide motifs in particular sequence contexts (PuPuCpGPyPy), which are greatly reduced in frequency in the mammalian genome, and where it occurs, the cytosine commonly is methylated. DNA containing unmethylated CpG motifs is immunostimulatory and able to activate cellular component of innate immunity, including macrophages and dendritic cells (DC) as well as B cells. Thus, DNA containing unmethylated CpG motif in sequences of PuPuCpGPyPy is also called ISS-DNA. Activation of immune cells by ISS-DNA appears to require uptake into the cells by receptor- or pinocytosis-mediated endocytosis and endosome acidification, suggesting that the recognition structure is either endosome-associated or cytoplasmic. Recent studies suggested that Toll-like receptor (TLR) 9 and adapter protein MyD88 are required for ISS-DNA to induce immune cells to produce interlukin-12, and for activation of NF-kB by ISS-ODN. The studies from our group suggested that catalytic subunit of DNA-dependent protein kinase (DNAPKcs) and IkB kinase (IKK) are required for the activation of innate immunity by ISS-DNA. ISS-DNA activates DNA-PKcs, which in turn activates IKK, leading to NF-kB activation. Null mutations in either the DNA-PKcs- or IKKb gene were found to selectively impair the ability of mice or their macrophages, to respond to ISS-DNA with inducible cytokine gene expression. TLR9 is on cell membrane while DNA-PKcs is in cytoplasm and nucleus. The connection between TLR9 and DNA-PKcs is not apparent. To further understand the molecular mechanisms of activation of innate immunity by ISS-DNA, we will investigate the relationship between TLR9-signaling pathway and DNA-PK by using biochemical and genetic means. Moreover, we will investigate if the regulatory subunits of DNA-PK, Ku70 and Ku80, and their associated factors are required for the innate response to ISS-DNA. Furthermore, we will identify new molecules that are required for activation of innate immunity by ISS-DNA.

描述(申请人提供)：先天免疫使生物体能够 对入侵的微生物做出快速反应。为此，先天免疫系统 使用多种受体或细胞内蛋白识别 病原菌相关分子模式的研究进展 (Pamps)。病原体相关的模体包括酵母细胞壁中的甘露糖， 甲酰化肽和各种细菌细胞壁成分，如 脂多糖(LPS)、脂肽、肽聚糖和磷壁酸。 细菌DNA也是天然免疫的有效诱导者。 细菌DNA中CpG二核苷酸基序的频率增加 特定的序列上下文(PuPuCpGPyPy)，在 在哺乳动物基因组中的频率，以及在它发生的地方，胞嘧啶通常 是甲基化的。含有未甲基化CpG基序的DNA具有免疫刺激作用 能够激活天然免疫的细胞成分，包括巨噬细胞 树突状细胞(DC)和B细胞。因此，含有未甲基化的DNA PuPuCpGPyPy序列中的CpG基序也称为ISS-DNA。激活 免疫细胞通过ISS-DNA似乎需要通过受体摄取到细胞- 或胞饮作用介导的内吞作用和内小体酸化，提示 识别结构要么是内体相关的，要么是细胞质的。近期 研究表明，Toll样受体(TLR)9和接头蛋白MyD88是 ISS-DNA诱导免疫细胞产生白细胞介素12所需的，以及 ISS-ODN对核因子-kB的激活作用我们小组的研究表明 DNA依赖蛋白激酶催化亚单位(DNAPKcs)和IKB激酶 (Ikk)是ISS-DNA激活天然免疫所必需的。ISS-DNA 激活DNA-PKcs，进而激活IKK，导致核因子-kB激活。 DNA-PKcs-或IKKB基因的零突变被发现选择性地 损害小鼠或其巨噬细胞对ISS-DNA的反应能力 可诱导的细胞因子基因表达。 TLR9位于细胞膜上，DNA-PKcs位于细胞质和胞核。这个 TLR9和DNA-PKcs之间的联系不明显。为了进一步了解 ISS-DNA激活天然免疫的分子机制，我们将 TLR9信号通路与DNA-PK关系的研究 生化和遗传手段。此外，我们将调查监管机构是否 DNA-PK、Ku70和Ku80亚基及其相关因子是必需的 对ISS-DNA的先天反应。此外，我们将识别新的分子 这是ISS-DNA激活先天免疫所必需的。