Crohn's disease-associated NOD2 Mutants

克罗恩病相关的 NOD2 突变体

• 批准号: 7731146
• 负责人: XIAOJING MA
• 金额: $ 42.25万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-26 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7731146
• 关键词: Accounting; Amino Acid Substitution; Antigen-Presenting Cells; B-Lymphocytes; Binding; Caspase; Cells; Clinical Research; Crohn' s disease; DNA Binding; Data; Development; Disease; Equilibrium; Frameshift Mutation; Gene Expression; Gene Targeting; Genes; Goals; Heterogeneous-Nuclear Ribonucleoproteins; Human; Immune; Immune response; Impairment; Individual; Infection; Inflammation; Inflammatory; Inflammatory Response; Interleukin-12; Intestinal Mucosa; Leucine-Rich Repeat; Link; Mitogen-Activated Protein Kinases; Mononuclear; Mutation; Myelogenous; Nuclear Translocation; Nucleotides; Pathogenesis; Pathology; Patients; Peptidoglycan; Phosphorylation; Positioning Attribute; Production; Property; Protein Family; Public Health; Regulatory Pathway; Research; Running; Signal Transduction; T-Cell Activation; Time; Toll-like receptors; base; cytokine; effective therapy; gain of function; human MAPK14 protein; inhibitor/antagonist; interleukin-23; leucine-rich repeat protein; loss of function; member; microbial; monocyte; mutant; novel; response; therapeutic target; transcription factor

Nucleotide-binding oligomerization domain 2 (NOD2) is a monocyte-restricted member of a protein family critically involved in the activation of NF-KB in response to certain intracellular microbial infection. Dysfunctional mutations in the NOD2 gene underline the occurrence of inflammatory bower disease (IBD) in a substantial group of patients with Crohn's disease (CD). CD is characterized by an exaggerated T helper I (Thl)-type immune response. There are three most common mutations in the NOD2 gene associated with CD: an insertion of a C at nucleotide position 3020, designated 3020insC, which results in a frame shift mutation and the deletion of the terminal leucine-rich repeats (LRR) of the protein, and two amino acid substitution mutants also in the LRR region: R702W and G908R. Recent human clinical studies revealed defective IL-IO production in the mononuclear cells of CD patients homozygous for 3020insC. IL-lO is a critical immunoregulatory cytokine produced by antigen-presenting cells and activated T and B lymphocytes. The chronically impaired IL-lO production in these CD patients may contribute to persistent inflammation in the intestinal mucosa. Our own data indicate that, in contrast to the prevalent view, 3020insC is not simply a loss-of-function mutant. Instead, it can act as an inhibitor of IL-lO production. Furthermore, we have detected direct interactions between 3020insC with p38 mitogen-activated protein kinase (MAPK) and heterogeneous nuclear ribonucleoprotein Al (hnRNP AI), which we identified as a novel and constitutive transcription factor for IL-lO. 3020insC targets the DNA-binding activity of hnRNP Al by inhibiting its phosphorylation and nuclear translocation. Most importantly, we have confirmed that the phosphorylation of hnRNP Al and DNA-binding activity are indeed impaired in 3020insC-CD patients. In addition, we have identified for the first time a novel activity of the R702W and G908R mutants: they can stimulate and enhance IL-12/IL-23 gene expression. We hypothesize that the acquired property of 3020insC as an IL-lO inhibitor may result in chronically impaired IL-IO levels, whereas the R702W and G908R mutations may make individuals more prone to produce elevated levels of IL-12 and IL-23 in the myeloid compartment. In all, these three mutations cause either impairment of regulatory mechanisms or inappropriate proinflammatory cytokine production, which, combined with other contributory factors, contribute to homeostatic imbalance and persistent inflammation in the intestinal mucosa over time leading to the development and pathogenesis of CD. We propose to investigate the mechanisms whereby R702W and G908R regulate IL-12/IL-23 gene expression.

核苷酸结合寡聚化结构域 2 (NOD2) 是蛋白质家族的单核细胞限制成员 关键参与 NF-KB 的激活以响应某些细胞内微生物感染。 NOD2 基因的功能失调突变强调了炎症性肠病 (IBD) 的发生 相当一部分患有克罗恩病（CD）的患者。 CD的特点是夸张的T辅助I (Thl)型免疫反应。与 CD 相关的 NOD2 基因存在三种最常见的突变： 在核苷酸位置 3020 处插入一个 C，指定为 3020insC，这会导致移码突变，并且 蛋白质末端富含亮氨酸重复序列 (LRR) 的删除，以及两个氨基酸取代突变体 也在 LRR 区域：R702W 和 G908R。 最近的人类临床研究表明 CD 患者的单核细胞中 IL-IO 的产生存在缺陷 3020insC 纯合。 IL-10是由抗原呈递细胞产生的关键免疫调节细胞因子 以及活化的T和B淋巴细胞。这些 CD 患者中长期受损的 IL-10 产生可能 导致肠粘膜持续炎症。我们自己的数据表明，与 普遍观点认为，3020insC 不仅仅是一个功能丧失突变体。相反，它可以充当IL-10的抑制剂 生产。此外，我们还检测到 3020insC 与 p38 丝裂原激活之间的直接相互作用 蛋白激酶 (MAPK) 和异质核核糖核蛋白 Al (hnRNP AI)，我们将其鉴定为 IL-10的新型组成型转录因子。 3020insC 靶向 hnRNP Al 的 DNA 结合活性 通过抑制其磷酸化和核转位。最重要的是，我们已经确认 hnRNP A1的磷酸化和DNA结合活性在3020insC-CD患者中确实受损。在 此外，我们首次鉴定了 R702W 和 G908R 突变体的新活性：它们可以 刺激和增强 IL-12/IL-23 基因表达。 我们假设 3020insC 作为 IL-10 抑制剂的获得性特性可能导致慢性 IL-IO 水平受损，而 R702W 和 G908R 突变可能使个体更容易产生 骨髓室中 IL-12 和 IL-23 水平升高。总之，这三种突变导致 调节机制受损或促炎细胞因子产生不当， 与其他影响因素一起，导致体内平衡失衡和持续炎症 随着时间的推移，肠粘膜的损伤导致CD的发展和发病。 我们建议研究R702W和G908R调节IL-12/IL-23基因的机制 表达。