Role of MLCK1 Trafficking in Epithelial Barrier Regulation

MLCK1 贩运在上皮屏障调节中的作用

• 批准号: 8060273
• 负责人: Emily Mariel Bradford
• 金额: $ 4.84万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8060273
• 关键词: Actomyosin; Adoptive Transfer; Adrenal Cortex Hormones; Adverse effects; Affect; Alternative Therapies; American; Anti-Tumor Necrosis Factor Therapy; Binding; Binding Proteins; Cell Adhesion Molecules; Characteristics; Crohn' s disease; Data; Development; Diarrhea; Disease Progression; Disease remission; Dominant-Negative Mutation; Epithelial; Epithelial Cells; Exons; FK506; Figs - dietary; First Degree Relative; Functional disorder; Gastrointestinal Diseases; Goals; Health; Immune response; Immunoglobulins; Immunosuppressive Agents; In Vitro; Incidence; Individual; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Intestines; Lead; Mediating; Molecular Chaperones; Myosin Light Chain Kinase; Neoplasms; Pathogenesis; Pathway interactions; Patients; Permeability; Pharmaceutical Preparations; Phosphotransferases; Process; Public Health; RNA Splicing; Regulation; Relapse; Research; Risk; Role; Severities; Signal Pathway; Signal Transduction Pathway; Site; Testing; Tight Junctions; Toxic effect; Training; Transgenic Mice; Tumor Necrosis Factor-alpha; Ulcerative Colitis; Variant; career development; clinical remission; clinically significant; cytokine; design; in vivo; inhibitor/antagonist; innovation; new therapeutic target; novel; prevent; small molecule; therapeutic target; trafficking

DESCRIPTION (provided by applicant): Inflammatory bowel disease (IBD) currently affects 1.4 million Americans. Reduced barrier function has been associated with active IBD and, interestingly, is also present in a subset of healthy, first-degree relatives of Crohn's disease patients. In patients with IBD, reduced barrier function during clinical remission is also associated with increased risk of relapse. Tumor necrosis factor (TNF), a central inflammatory cytokine in IBD, causes barrier dysfunction via myosin light chain kinase (MLCK) activation and subsequent tight junction dysregulation. Moreover, MLCK expression and activity are also increased in IBD patients. These data suggest that TNF- and MLCK-dependent barrier dysfunction contribute to IBD pathogenesis. One MLCK splice variant, MLCK1, contains a unique immunoglobulin-cell adhesion molecule (IgCAM) domain, IgCAM3, that is not present in the other variants of MLCK1. Consistent with a unique role for IgCAM3 in trafficking, MLCK1, but not MLCK2, is concentrated at the perijunctional actomyosin ring and our preliminary data show that MLCK1 trafficking is required for TNF-induced barrier loss in vitro and in vivo. These preliminary data suggest that MLCK1 trafficking is essential to TNF-induced barrier loss in IBD. The aims of this proposal are to i) identify the domains of MLCK1 that are required for MLCK1 trafficking to the perijunctional actomyosin ring, ii) define the role of the chaperone FKBP8 in MLCK1 localization and iii) characterize small molecules that specifically disrupt MLCK1 trafficking to the perijunctional actomyosin ring and reduce increased intestinal permeability in vivo. Although most current therapies directed at IBD are centered on suppressing the immune response (e.g. corticosteroids and anti-TNF therapies), long-term use of these therapies carries significant risk of other complications. Thus, alternative therapies that can be used to maintain remission are needed. We have hypothesized that inhibition of MLCK1 trafficking, which should have very few side effects, will blunt barrier dysregulation induced by TNF and related cytokines and thus help to maintain remission in patients and perhaps prevent IBD development in at-risk individuals. These studies are significant because they will be the first step toward understanding the mechanisms by which MLCK1 trafficking is in involved in TNF-induced barrier dysregulation, and they will define a signaling pathway that can be targeted therapeutically. PUBLIC HEALTH RELEVANCE: Inflammatory bowel disease (IBD), characterized by increased intestinal permeability and reduced barrier function, currently affects 1.4 million Americans. The proposed studies will delineate a novel signaling pathway involved in barrier regulation and will define the characteristics of small molecule drugs that can be used to target that pathway therapeutically. The data generated from these studies will have a significant public health impact, as the development of novel drugs with low toxicity is critical for reducing both the incidence of relapse in IBD and the health risks associated with long-term use of the current immunosuppressive drugs that are currently used to treat IBD.

描述（由申请人提供）：炎症性肠病（IBD）目前影响140万美国人。障碍功能的降低与主动IBD有关，有趣的是，在克罗恩病患者的健康，一级亲属的一部分中也存在。在IBD患者中，临床缓解期间的屏障功能降低也与复发风险增加有关。肿瘤坏死因子（TNF）是IBD中的一种中枢炎症细胞因子，通过肌球蛋白轻链激酶（MLCK）激活引起屏障功能障碍，然后随后的紧密连接失调。此外，IBD患者的MLCK表达和活性也增加。这些数据表明TNF和MLCK依赖性屏障功能障碍有助于IBD发病机理。一个MLCK剪接变体MLCK1包含一个独特的免疫球蛋白细胞粘附分子（IGCAM）域IGCAM3，它在MLCK1的其他变体中不存在。与IgCAM3在运输中的独特作用一致，MLCK1（而不是MLCK2）集中在骨周围的肌动蛋白环上，我们的初步数据表明，MLCK1运输是TNF诱导的障碍物在体外和体内所诱导的屏障损失所必需的。 这些初步数据表明，MLCK1运输对于TNF引起的IBD屏障损失至关重要。 The aims of this proposal are to i) identify the domains of MLCK1 that are required for MLCK1 trafficking to the perijunctional actomyosin ring, ii) define the role of the chaperone FKBP8 in MLCK1 localization and iii) characterize small molecules that specifically disrupt MLCK1 trafficking to the perijunctional actomyosin ring and reduce increased intestinal permeability in体内。尽管目前针对IBD的大多数疗法都以抑制免疫反应（例如皮质类固醇和抗TNF疗法）为中心，但这些疗法的长期使用带来了其他并发症的重大风险。因此，需要用于维持缓解的替代疗法。我们假设抑制MLCK1贩运的副作用应该很少，它将钝化TNF和相关细胞因子诱导的障碍失调，从而有助于维持患者的缓解，甚至可以预防高危人群的IBD发育。这些研究之所以重要，是因为它们将是了解MLCK1运输与TNF诱导的屏障失调有关的机制的第一步，并且它们将定义可以针对治疗的信号传导途径。 公共卫生相关性：炎症性肠病（IBD），其特征是肠道通透性增加和屏障功能降低，目前影响140万美国人。拟议的研究将描绘出涉及屏障调节的新型信号通路，并将定义小分子药物的特征，该药物可用于治疗途径。这些研究产生的数据将产生重大的公共卫生影响，因为毒性低的新药物的开发对于降低IBD复发的发生率和与当前用于治疗IBD的当前免疫抑制药物相关的健康风险至关重要。