SGK1 is a Central Regulator of P. gingivalis-Induced Inflammation

SGK1 是牙龈卟啉单胞菌引起的炎症的中央调节器

• 批准号: 8570618
• 负责人: Huizhi Wang
• 金额: $ 22.5万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8570618
• 关键词: Affect; Atherosclerosis; Back; Binding; Boxing; CCAAT-Enhancer-Binding Protein-beta; CCAAT-Enhancer-Binding Proteins; Cells; Chronic; Computer software; Cyclic AMP-Dependent Protein Kinases; Data; Development; Diabetes Mellitus; Disease; Exploratory/Developmental Grant for Diagnostic Cancer Imaging; Family; Figs - dietary; Genes; Glucocorticoids; Gram-Negative Anaerobic Bacteria; Immune; Immune response; Immune system; Inflammation; Inflammation Mediators; Inflammatory; Inflammatory Response; Low Birth Weight Infant; Mediating; Microbe; Modification; Molecular; Nature; Nuclear; Oral cavity; Outcome; Pathway interactions; Pattern; Periodontitis; Periodontium; Phosphatidylinositols; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Porphyromonas gingivalis; Predisposition; Process; Production; Protein-Serine-Threonine Kinases; Proteins; Publications; Receptor Signaling; Regulation; Role; Septic Shock; Serine; Serum; Signal Pathway; Signal Transduction; Small Interfering RNA; System; Systemic disease; TLR2 gene; TLR4 gene; Therapeutic; Time; Toll-Like Receptor 2; Toll-like receptors; Tretinoin; Work; base; cytokine; high reward; in vivo; inhibitor/antagonist; innovation; microbial; novel; nucleotide receptor; promoter; public health relevance; receptor; research study; response; success; therapeutic target

DESCRIPTION (provided by applicant): Porphyromonas gingivalis (P. gingivalis) is a Gram-negative anaerobic bacterium and a causative agent of periodontitis. Studies assessing the host inflammatory response to P. gingivalis have demonstrated that Toll-like receptor (TLR)-2 is the predominant TLR involved in the recognition of LPS and various other microbe-associated molecular patterns of P. gingivalis. However, the underlying cell-signaling pathways, especially the intracellular regulatory molecules, regulating the P. gingivalis (TLR2)-mediated inflammatory response are not fully understood. Using siRNA and Cre/loxP system, we have, for the first time, identified that serum- and glucocorticoid-inducible kinase 1 (SGK1) suppresses P. gingivalis-mediated inflammatory responses in innate immune cells. SGK1 is a ubiquitous serine/theronine kinase belonging to AGC kinase family (Protein kinase A, -G and -C family) and can be activated by PI3 kinase. Whereas the PI3K-Akt-GSK3-¿ pathway has been demonstrated to play a critical regulatory role in TLR-mediated inflammatory responses, the functional role of SGK1 in TLR-mediated immune responses is entirely unknown. Therefore, the studies proposed here are intend to identify and characterize how SGK1 regulates P. gingvalis induced inflammatory mediators, as well as to delineate how the TLRs are involved in the phosphorylation and activation of SGK1. We hypothesize SGK1 is a critical kinase that controls inflammation of innate immune cells upon stimulation with P. gingivalis by regulating activation of Forkhead box protein O1 (FoxO1) and its downstream CCAAT/enhancer-binding protein beta (C/EBP-¿). This hypothesis is further substantiated by (i) the prediction of phosphorylation sites (by the software NetworKIN) identified FoxO1 as the optimum substrate of SGK1; (ii) our preliminary data showing that P. gingivalis stimulation phospho-activates SGK1 and abolishes the binding of FoxO1 to the promoter of C/EBP-¿ in BMDC; and (iii) our recent publication demonstrating that PDK2 inhibition mediates FoxO1 nuclear sequestration and enhances TLR4 mediated inflammatory responses in innate immune cells (15). These observations provide a strong rationale for SGK1 in modulating P. gingivalis mediated inflammatory response via the TLR2-SGK1-FoxO1-C/EBP-¿ axis. The specific aims will establish the role for SGK1 as an endogenous inhibitor of the P. gingivalis-mediated inflammatory response and delineate how SGK1 is activated in response to P. gingivalis stimulation, as well as determine if SGK1 negatively regulates P. gingivalis induced pro-inflammatory cytokines production via modification of the activity of FoxO1 and its downstream C/EBP-¿ . Successful completion of this project will result in the isolation a novel and potentiall critical signaling pathway (TLR2-PI3K-SGK1-FoxO1-C/EBP-¿ ) and greatly aid in the understanding of how the host inflammatory response is being regulated, which will pave the way for the development of immunoregulatory therapeutics that should have relevance well beyond the oral cavity.

描述（由申请人提供）：牙龈卟啉单胞菌（P.gingivalis）是一种革兰氏阴性厌氧细菌，也是牙周炎的致病菌。评估宿主对牙龈卟啉单胞菌炎症反应的研究表明，Toll 样受体（TLR）-2。是参与识别 LPS 和牙龈卟啉单胞菌的各种其他微生物相关分子模式的主要 TLR。调节牙龈卟啉单胞菌 (TLR2) 介导的炎症反应的潜在细胞信号传导途径，特别是细胞内调节分子尚未完全了解。使用 siRNA 和 Cre/loxP 系统，我们首次确定了血清和糖皮质激素诱导激酶 1 (SGK1) 可抑制先天免疫细胞中牙龈卟啉单胞菌介导的炎症反应。SGK1 是一种普遍存在的丝氨酸/苏氨酸激酶。属于AGC激酶家族（蛋白激酶A、-G和-C家族），可以被PI3激酶激活。已证明 SGK1 通路在 TLR 介导的炎症反应中发挥关键的调节作用，但 SGK1 在 TLR 介导的免疫反应中的功能作用完全未知，因此，本文提出的研究旨在鉴定和表征 SGK1 如何调节牙龈卟啉单胞菌。诱导炎症介质，以及描述 TLR 如何参与 SGK1 的磷酸化和激活，我们发现 SGK1 是一种关键激酶，可在刺激后控制先天免疫细胞的炎症。通过调节 Forkhead box 蛋白 O1 (FoxO1) 及其下游 CCAAT/增强子结合蛋白 β (C/EBP-¿) 的激活，这一假设得到了 (i) 磷酸化位点的预测（通过(ii) 我们的初步数据显示牙龈卟啉单胞菌刺激磷酸激活 SGK1 并消除FoxO1 与 C/EBP-¿ 启动子的结合在 BMDC 中；以及 (iii) 我们最近发表的文章证明 PDK2 抑制介导 FoxO1 核隔离并增强先天免疫细胞中 TLR4 介导的炎症反应 (15)。这些观察结果为 SGK1 通过调节牙龈卟啉单胞菌介导的炎症反应提供了强有力的理论依据。 TLR2-SGK1-FoxO1-C/EBP-¿具体目标将确定 SGK1 作为牙龈卟啉单胞菌介导的炎症反应的内源性抑制剂的作用，并描述 SGK1 如何响应牙龈卟啉单胞菌刺激而被激活，以及确定 SGK1 是否负调节牙龈卟啉单胞菌诱导的炎症反应。通过修改 FoxO1 及其下游 C/EBP-¿ 的活性产生促炎细胞因子该项目的成功完成将导致分离出一种新颖且潜在的关键信号通路（TLR2-PI3K-SGK1-FoxO1-C/EBP-¿），并极大地有助于了解宿主炎症反应是如何被调节的，这将为免疫调节疗法的发展铺平道路，这种疗法应该远远超出口腔范围。