Rho GTPase-mediated pathways in autoimmune arthritis

Rho GTPase 介导的自身免疫性关节炎通路

• 批准号: 8230157
• 负责人: ALESSANDRA B PERNIS
• 金额: $ 43.88万
• 依托单位: HOSPITAL FOR SPECIAL SURGERY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8230157
• 关键词: Adverse effects; Arthritis; Autoantigens; Autoimmune Responses; Autoimmunity; Binding; Binding Proteins; Biological; Biology; CD4 Positive T Lymphocytes; Cardiovascular Diseases; Cell Nucleus; Cells; Clinical Trials; Clone Cells; Development; Disease; Effectiveness; Event; Exhibits; Genes; Genetic; Goals; Guanine Nucleotide Exchange Factors; IRF4 gene; Immune response; Interleukin-17; Kidney Diseases; Knowledge; Mediating; Modeling; Molecular; Mus; Names; Pathway interactions; Phosphorylation; Play; Production; Protein Isoforms; Proteins; Reporting; Rho-associated kinase; Role; Signal Pathway; Signal Transduction; Syndrome; Systemic Lupus Erythematosus; T-Lymphocyte; Testing; Therapeutic; Transgenic Organisms; Translating; Treatment Efficacy; Treatment Protocols; autoimmune arthritis; cytokine; fasudil; inhibitor/antagonist; lupus-like; novel; novel strategies; novel therapeutics; prevent; promoter; response; rho GTP-Binding Proteins; therapeutic target; transcription factor

DESCRIPTION (provided by applicant): Rho GTPases (which include Rac and RhoA) are molecular switches that play a fundamental role in biology due to their ability to regulate both cytoskeletal dynamics and signaling pathways. Rac and RhoA target different effectors and thus regulate distinct signaling events. Rac and RhoA also cross-regulate each other since activated Rac inhibits RhoA activity and vice versa. One of the major effectors of RhoA is the Rho kinases (or ROCKs). Activation of Rho GTPases plays a key role in immune responses. Guanine nucleotide exchange factors (GEFs) are the major proteins regulating the activation of Rho GTPases. In the course of isolating proteins interacting with IRF4, a transcription factor required for the differentiation of TH-17 cells, we cloned a novel GEF that we termed IBP (IRF-4 Binding Protein), also known as Def6. Since Def6 is the official name of the gene, IBP will be hereafter referred to as Def6. Def6 is highly expressed in T cells, and, upon TCR engagement, activates Rac but not RhoA. Def6 can also be found in the nucleus where it interacts with IRF4. We previously reported that Def6-deficient mice spontaneously develop a lupus-like syndrome. We have recently found that TCR transgenic (DO11.10) Def6-deficient mice spontaneously develop RA-like arthritis. The autoimmune responses in these mice are due to an aberrant ability of CD4+ T cells to produce IL-17 and IL-21 in response to self-antigens. At a molecular level, Def6-deficient T cells exhibit defective Rac activation and an enhanced ability of IRF4 to bind to the IL-17 and IL-21 promoters. Consistent with the notion that Rac activation inhibits RhoA- induced pathways, we have recently observed that the absence of Def6 also leads to increased ROCK2 activity. Importantly, we have found that ROCK2 phosphorylates IRF4 and regulates its ability to control the production of IL-17 and IL-21. In line with these findings, Fasudil, a ROCK inhibitor, blocked the aberrant IL-17 and IL-21 production detected in the absence of Def6 and prevented development of arthritis in Def6-deficient DO11.10 mice. We now propose that the Def6-ROCK2-IRF4 axis regulates the production of IL-17 and IL-21 and that ROCK inhibitors represent a novel approach for the treatment of autoimmune arthritis. The specific goals of this proposal are: 1) To investigate the interplay between Def6 and ROCK2, 2) to delineate the role of T-cell ROCK2 in autoimmune arthritis and 3) to broadly assess the effectiveness of ROCK inhibitors in autoimmune arthritis. PUBLIC HEALTH RELEVANCE: These studies will provide crucial information into the mechanisms controlling the production of potentially pathogenic cytokines like IL-17 and IL-21. Given that ROCK inhibitors have already been used for the treatment of cardiovascular disorders and are well tolerated, the knowledge derived from these studies could also be rapidly translated into novel therapeutic regimens for the treatment of SLE and RA.

描述（由申请人提供）：Rho GTPases（包括RAC和RHOA）是分子开关，由于它们能够调节细胞骨架动力学和信号通路，因此在生物学中起着基本作用。 RAC和RHOA靶向不同的效应子，因此调节不同的信号事件。 RAC和Rhoa也相互调节，因为激活的RAC抑制了RhoA活性，反之亦然。 RhoA的主要效应因子之一是Rho激酶（或岩石）。 Rho GTPases的激活在免疫反应中起关键作用。鸟嘌呤核苷酸交换因子（GEFS）是调节Rho GTPases激活的主要蛋白质。在分离蛋白与IRF4相互作用的过程中，IRF4是分化Th-17细胞所需的转录因子的过程，我们克隆了一种新型GEF，我们称为IBP（IRF-4结合蛋白），也称为DEF6。由于DEF6是该基因的官方名称，因此IBP将被称为DEF6。 DEF6在T细胞中高度表达，并且在TCR参与后激活RAC，但没有激活RhoA。 DEF6也可以在与IRF4相互作用的核中找到。我们先前曾报道过DEF6缺陷小鼠自发发展狼疮样综合征。我们最近发现，TCR转基因（DO11.10）缺陷型小鼠会自发发展RA样关节炎。这些小鼠的自身免疫反应是由于CD4+ T细胞对自我抗原的反应产生IL-17和IL-21的异常能力。在分子水平上，DEF6缺陷的T细胞表现出有缺陷的RAC激活以及IRF4与IL-17和IL-21启动子结合的能力增强。与RAC激活抑制RhoA诱导的途径的观点一致，我们最近观察到，缺乏DEF6也会导致Rock2活性增加。重要的是，我们发现Rock2磷酸化IRF4并调节其控制IL-17和IL-21产生的能力。根据这些发现，岩石抑制剂Fasudil在没有DEF6的情况下阻止了异常的IL-17和IL-21产生，并阻止了DEF6缺陷DO11.10小鼠的关节炎。现在，我们建议DEF6-ROCK2-IRF4轴调节IL-17和IL-21的产生，并且岩石抑制剂代表了一种治疗自身免疫性关节炎的新方法。该提案的具体目标是：1）研究DEF6和ROCK2之间的相互作用2），2）描绘T-Cell Rock2在自身免疫性关节炎中的作用和3）3）广泛评估岩石抑制剂在自身免疫性关节炎中的有效性。 公共卫生相关性：这些研究将为控制潜在的致病细胞因子（如IL-17和IL-21）产生的机制提供关键信息。鉴于岩石抑制剂已经被用于治疗心血管疾病并具有良好的耐受性，因此从这些研究中得出的知识也可以迅速转化为新型治疗方案，以治疗SLE和RA。