Crohn's disease-associated NOD2 Mutants

核苷酸结合寡聚域2(NOD2)是蛋白质家族中单核细胞限制性的成员 在应对某些细胞内微生物感染时，关键参与了核因子-kB的激活。 NOD2基因的功能异常突变强调了炎症性肠病(IBD)的发生 大量克罗恩病(CD)患者。CD的特点是一个夸张的T助手I (Thl)型免疫反应。与CD相关的NOD2基因有三种最常见的突变： 在核苷酸位置3020插入C，命名为3020insC，这导致移码突变和 该蛋白富含亮氨酸末端重复序列(LRR)的缺失，以及两个氨基酸替代突变体 同样在LRR区域：R702W和G908R。 最近的人类临床研究发现CD患者单个核细胞产生的IL-IO存在缺陷 3020insC纯合子。IL-LO是一种由抗原提呈细胞产生的重要免疫调节细胞因子 激活T、B淋巴细胞。这些CD患者的IL-LO产生的慢性损害可能 导致肠粘膜持续发炎。我们自己的数据表明，与 流行观点认为，3020insC不是一个简单的功能缺失突变体。相反，它可以作为IL-LO的抑制剂 制作。此外，我们还检测到3020insC与p38丝裂原激活的直接相互作用 蛋白激酶(MAPK)和异质性核糖核蛋白A1(HnRNP AI)，我们鉴定为一种 IL-10的新的组成型转录因子。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 3020insC-CD患者hnRNP Al的磷酸化和DNA结合活性确实受损。在……里面 此外，我们首次鉴定了R702W和G908R突变体的一种新活性：它们可以 刺激和增强IL-12/IL-23基因表达。 我们推测，3020insC作为IL-LO抑制剂的获得性可能导致慢性 IL-IO水平受损，而R702W和G908R突变可能使个体更容易产生 髓鞘内IL-12和IL-23水平升高。总而言之，这三个突变会导致 调节机制受损或不适当的促炎细胞因子产生，两者结合在一起 与其他因素一起，导致体内平衡失衡和持续炎症 肠黏膜随着时间的推移导致CD的发生发展和发病机制。 我们建议研究R702W和G908R调节IL-12/IL-23基因的机制 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.