Understanding the role of IFN-gamma and CIITA in skeletal muscle

了解 IFN-γ 和 CIITA 在骨骼肌中的作用

基本信息

批准号：
8958379
负责人：
Judith Kimberly Davie
金额：
$ 38.94万
依托单位：
SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-08-01 至 2021-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8958379
关键词：
Address Affect Age Animals Biological Assay Cachexia Catalytic Domain Cessation of life Chronic Clinical Complex Data Development Disease Drug Design EZH2 gene Engineering Epigenetic Process Event Foundations Gene Expression Gene Expression Profile Gene Targeting Genes Goals Healed Health Histone H3 Human Indium Individual Inflammation Inflammatory Inflammatory Infiltrate Inflammatory Response Injury Innovative Therapy Interferon Type II Interferons Interleukin-6 Knowledge Life Locomotion Lysine MHC class II transactivator protein Mediating Methylation Modification Molecular Mus Muscle Muscle function Muscular Dystrophies Myogenic Regulatory Factors Myogenin Myopathy Myositis Natural regeneration Patients Pattern Phase Play Polycomb Process Proteins Recruitment Activity Regulation Repression Role Signal Transduction Skeletal Muscle Staging Therapeutic Intervention Trauma Up-Regulation Withdrawal Work cytokine healing improved in vivo insight mdx mouse mouse model muscle regeneration myogenesis novel programs promoter public health relevance repaired response treatment strategy

项目摘要

DESCRIPTION (provided by applicant): The objective of this study is to identify how the inflammatory cytokine, interferon gamma (IFN-, which is up regulated in response to muscle injury resulting from trauma or disease, modulates muscle function and repair. The repair of skeletal muscle is essential to human health and inefficient repair leads to a loss of locomotion and eventually, to death. The inflammatory response plays an important role in responding to injury and initiating skeletal muscle repair. IFN- plays both positive and negative roles in myogenesis and is required for efficient muscle regeneration in vivo. We have discovered that IFN- acts through the class II transactivator, CIITA, by repressing the expression or activity o myogenin, the Myogenic Regulatory Factor (MRF) required for myofiber formation. In our studies to understand the mechanism of CIITA repression, we have discovered that IFN-, through CIITA, acts to maintain the expression of the polycomb complex, PRC2, which is normally silenced during differentiation. CIITA recruits the PRC2 complex to repressed gene promoters and PRC2 represses gene expression by catalyzing the methylation of histone H3, lysine 27 (H3K27me3). We propose that transient expression of IFN-, through CIITA, modulates myogenesis and promotes muscle repair, but suggest that deregulation of this signaling contributes to muscle disease by altering the gene expression profile in myofibers subject to IFN- stimulation. In this proposal, we will determine how IFN- and CIITA repress myogenin by determining if recruitment of activating factors such as MyoD are blocked in the presence of IFN-, defining the epigenetic modifications used in the repression and determining whether the PRC2 complex is required for repression. Next, we will determine if genes known to be altered in H3K27me3 patterns upon differentiation are methylated in response to IFN- and dependent on myogenin. These data will be correlated with the recruitment of EZH2 and the repression of gene expression. Lastly, we will confirm our findings in vivo and determine if chronic IFN- can inhibit muscle repair. This work will utilize a new mouse model engineered to express low chronic levels of IFN-. Using this mouse model, we will characterize the expression of CIITA and the PRC2 complex, determine if IFN- target genes are deregulated, and characterize repair in the presence of chronic IFN-. To understand the impact of IFN- as part of the inflammatory infiltrate, the methylation profile and gene expression of IFN- regulated gene targets will be assayed in mdx mice, which are known to have enhanced IFN- expression as part of a chronic inflammation response. The proposed work will strengthen our understanding of the molecular events that occur during inflammation in skeletal muscle. This information will not only help elucidate the normal process of repair and regeneration, but also extend our knowledge about the potential deleterious effects of chronic inflammation, enhancing the understanding of diseases such as muscular dystrophy, cachexia and inflammatory myopathies and allowing the development of innovative therapies for these diseases.

描述（由申请人提供）：本研究的目的是确定炎症细胞因子、干扰素 γ (IFN-γ，因创伤或疾病导致的肌肉损伤而上调)如何调节肌肉功能和骨骼修复。肌肉对人类健康至关重要，低效修复会导致运动能力丧失，并最终导致死亡。炎症反应在响应损伤和启动骨骼肌修复方面发挥着重要作用。 IFN-γ 在肌生成中发挥积极和消极作用，并且是体内肌肉再生所必需的。我们发现 IFN-γ 通过 II 类反式激活因子 CIITA 抑制肌生成素（肌生成有效调节因子）的表达或活性发挥作用。在我们了解 CIITA 抑制机制的研究中，我们发现 IFN-γ 通过 CIITA 发挥作用来维持多梳的表达。 CIITA 复合物，PRC2，通常在分化过程中被沉默，它会招募 PRC2 复合物来抑制基因启动子，并且 PRC2 通过催化组蛋白 H3 赖氨酸 27 (H3K27me3) 的甲基化来抑制基因表达。 CIITA 可调节肌生成并促进肌肉修复，但表明这种信号传导的失调会通过改变基因而导致肌肉疾病受 IFN-γ 刺激的肌纤维中的表达谱在本提案中，我们将通过确定在 IFN-γ 存在的情况下是否阻断 MyoD 等激活因子的募集来确定 IFN-γ 和 CIITA 如何抑制肌生成素，从而定义表观遗传修饰。接下来，我们将确定在分化时 H3K27me3 模式中已知改变的基因是否被甲基化。这些数据将与 EZH2 的募集和基因表达的抑制相关。最后，我们将在体内证实我们的发现并确定慢性 IFN-α 是否可以抑制肌肉修复。将利用一种新的小鼠模型来表达低水平的 IFN-γ 使用该小鼠模型，我们将表征 CIITA 和 PRC2 复合物的表达，确定 IFN-γ 靶基因是否失调。并表征慢性 IFN-γ 存在下的修复特征为了了解 IFN-γ 作为炎症浸润的一部分的影响，将在已知的 mdx 小鼠中检测 IFN-γ 调节的基因靶标的甲基化谱和基因表达。增强 IFN-γ 表达作为慢性炎症反应的一部分将加强我们对骨骼肌炎症期间发生的分子事件的理解。阐明修复和再生的正常过程，同时也扩展了我们对慢性炎症潜在有害影响的认识，增强了对肌营养不良、恶病质和炎症性肌病等疾病的了解，并开发了针对这些疾病的创新疗法。