Crohn's disease-associated NOD2 Mutants

核苷酸结合寡聚化结构域2（NOD 2）是蛋白质家族的单核细胞限制性成员 关键地参与响应某些细胞内微生物感染的NF-κ B的活化。 NOD 2基因的功能失调突变强调了炎症性鲍尔病（IBD）的发生， 大量克罗恩病（CD）患者。CD的特征是T辅助细胞I的过度表达， （Thl）型免疫应答。NOD 2基因中有三种最常见的与CD相关的突变： - 在核苷酸位置3020处插入C，命名为3020 insC，其导致移码突变， 蛋白质末端富含亮氨酸重复序列（LRR）的缺失，以及两个氨基酸取代突变体 也在LRR区域：R702 W和G908 R。 最近的人类临床研究显示CD患者单核细胞中IL-10的产生缺陷 3020 insC纯合子。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患者中的慢性受损的IL-10产生可能 导致肠粘膜的持续炎症。我们自己的数据表明，与 普遍的观点认为，3020 insC不仅仅是一个功能丧失的突变体。相反，它可以作为IL-10的抑制剂， 生产此外，我们还检测到3020 insC与p38丝裂原激活的 蛋白激酶（MAPK）和异质性核核糖核蛋白AI（hnRNP AI），我们将其鉴定为 IL-10的新的组成型转录因子。3020 insC靶向hnRNPAl的DNA结合活性 通过抑制其磷酸化和核转位。最重要的是，我们已经证实， hnRNPA 1的磷酸化和DNA结合活性在3020 insC-CD患者中确实受损。在 此外，我们首次鉴定了R702 W和G908 R突变体的新活性：它们可以 刺激并增强IL-12/IL-23基因表达。 我们假设3020 insC作为IL-10抑制剂的获得性特性可能导致慢性炎症。 IL-10水平受损，而R702 W和G908 R突变可能使个体更容易产生IL-10， 髓腔中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， 与其他因素一起，导致体内平衡失衡和持续性炎症， 随着时间的推移，肠粘膜的损伤导致CD的发展和发病。 我们拟探讨R702 W和G908 R对IL-12/IL-23基因的调控机制 表情

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.