Understanding the Role of the Class II Activator, CIITA, in Skeletal Muscle

了解 II 类激活剂 CIITA 在骨骼肌中的作用

基本信息

批准号：
8103601
负责人：
Judith Kimberly Davie
金额：
$ 39.29万
依托单位：
SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-04-05 至 2015-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8103601
关键词：
Affinity Age Aging Alleles Antibodies Binding Biological Assay Bromodeoxyuridine Cell Line Cells Cessation of life Clinical Commit Complex Data Differentiation Antigens Direct Lytic Factors Disease Down-Regulation Embryo Family Fiber Freezing Gene Expression Genes Harvest Hematoxylin and Eosin Staining Method Human Human Biology Immune Immunohistochemistry Inflammation Inflammatory Response Injury Interferon Type II Interferons Life Link MHC class II transactivator protein Mediating Mediator of activation protein Molecular Morphology Mus Muscle Muscle Cells Muscle Fibers Muscular Dystrophies Myoblasts Myogenic Regulatory Factors Myogenin Myopathy Myosin Heavy Chains Natural regeneration Normal Cell Pathway interactions Play Process Proteins RNA Repression Research Design Role STAT1 gene Signal Transduction Skeletal Muscle Staging Staining method Stains System Testing Time Transcription Coactivator Western Blotting Work chromatin immunoprecipitation cytokine in vivo inhibitor/antagonist insight interferon gamma receptor interferon gamma receptors knock-down muscle regeneration myogenesis normal aging novel promoter receptor repaired research study response satellite cell skeletal muscle differentiation small hairpin RNA

项目摘要

DESCRIPTION (provided by applicant): Skeletal muscle has a remarkable ability to grow and repair throughout life. Deficiencies in skeletal muscle regeneration contribute to normal human aging and muscular dystrophies. Understanding both the process of how muscle senses damage and the molecular details of how muscle is repaired are of central importance in human biology. We believe that we have identified a novel connection between the inflammatory response and skeletal muscle remodeling mediated by the myogenic regulatory family (MRF). The inflammatory response plays an important role in initiating skeletal muscle regeneration. One of the cytokines involved in the inflammation response is the anti-fibrotic agent interferon gamma (IFN-?). IFN-? has complex effects on myogenesis, but is required for efficient muscle regeneration in vivo. We have identified the class II transactivator, CIITA, as a factor that interacts with myogenin, the MRF that mediates terminal differentiation. In immune cells, IFN-? stimulates both the activation and repression of a large set of genes through the action of CIITA, which serves as both a co-activator and co-repressor. CIITA is activated by IFN-? through the JAK/STAT pathway which leads to the direct activation of CIITA by STAT1. CIITA has both constitutive and IFN-? stimulated roles in the cell. We have confirmed that CIITA is expressed in the C2C12 myoblast line and shown that CIITA acts as a specific inhibitor of myogenin's activity as a transcriptional activator of muscle specific genes. CIITA expression is stimulated by IFN-?, and both stimulation with IFN-? and over expression of CIITA down regulate muscle specific gene expression and inhibit differentiation. Thus, we hypothesize that CIITA is the mediator of the IFN-? signal in skeletal muscle cells. In this proposal, we seek to understand how CIITA contributes to myogenesis and muscle repair. First, we propose to extend our current work on the role of CIITA in myoblasts by confirming our preliminary findings in primary myoblasts and confirming the anti-differentiation effect of CIITA with over expression and knock down studies. We also plan to initiate studies on the role of IFN-? in normal myogenesis by characterizing the level of IFN-? produced by myoblasts and by blocking the IFN-? receptor to assay the effects of loss of IFN-? signaling. Next, we seek to understand the contribution of CIITA to muscle repair by conducting muscle damage studies on mice with a disruption of the CIITA allele. Finally, we seek to determine if CIITA is the mediator of IFN-? and STAT1 signaling in myoblasts. Our preliminary data suggests that CIITA and its inhibition of myogenin are responsible for many of the effects of IFN-? and STAT1 on myogenic cells. We will attempt to support our hypothesis by confirming that STAT1 activates CIITA in myoblasts and by using STAT1 inhibitors to confirm a loss of anti differentiation effects following IFN-? stimulation. We will then attempt to rescue this effect by over expressing CIITA. We will also assay for IFN-? effects in Myog-/- myoblasts to determine if myogenin is required to mediate the IFN-? mediated down regulation of muscle specific targets. PUBLIC HEALTH RELEVANCE: Skeletal muscle is able to grow and repair throughout life. When muscle cannot be repaired due to age or muscular dystrophies, this leads to a loss of the ability to move and eventually leads to death. This proposal seeks to characterize a novel link between the signaling induced by the inflammatory response to muscle damage and the factors that can repair muscle fibers. We have discovered a factor in skeletal muscle cells that both responds to the signals released from inflammation and represses the activity of a specific factor required for the final steps in rebuilding muscle. We propose that this system gives muscle the time it needs to initiate repair before committing to the final steps of repair. This proposal seeks to further characterize this factor in muscle cells and determine its cellular role in skeletal muscle differentiation and repair. This work has important implications in understanding how skeletal muscle repairs itself after injury and may be able to offer novel insight into how to stimulate muscle regeneration in the case of aging or disease.

描述（由申请人提供）：骨骼肌在一生中具有非凡的生长和修复能力。骨骼肌再生缺陷会导致人类正常衰老和肌肉营养不良。了解肌肉如何感知损伤的过程以及肌肉如何修复的分子细节对于人类生物学至关重要。我们相信，我们已经确定了由肌源性调节家族（MRF）介导的炎症反应和骨骼肌重塑之间的新联系。炎症反应在启动骨骼肌再生中起着重要作用。参与炎症反应的细胞因子之一是抗纤维化剂γ干扰素（IFN-α）。干扰素-?对肌生成具有复杂的影响，但却是体内有效肌肉再生所必需的。我们已经鉴定出 II 类反式激活因子 CIITA 是与肌生成素（介导终末分化的 MRF）相互作用的因子。在免疫细胞中，IFN-?通过 CIITA 的作用刺激大量基因的激活和抑制，CIITA 既充当共激活子又充当共阻遏子。 CIITA 被 IFN-α 激活。通过 JAK/STAT 途径导致 STAT1 直接激活 CIITA。 CIITA同时具有本构型和IFN-？刺激细胞中的作用。我们已经证实 CIITA 在 C2C12 成肌细胞系中表达，并表明 CIITA 作为肌细胞生成素活性的特异性抑制剂，作为肌肉特异性基因的转录激活剂。 CIITA表达受IFN-α刺激，并且均受IFN-α刺激。 CIITA 的过度表达下调肌肉特异性基因表达并抑制分化。因此，我们假设 CIITA 是 IFN-α 的介体。骨骼肌细胞中的信号。在本提案中，我们试图了解 CIITA 如何促进肌生成和肌肉修复。首先，我们建议通过证实我们在原代成肌细胞中的初步发现并通过过表达和敲低研究证实 CIITA 的抗分化作用，来扩展我们目前关于 CIITA 在成肌细胞中的作用的工作。我们还计划启动关于 IFN-α 作用的研究。通过表征 IFN-α 的水平来影响正常的肌生成。由成肌细胞产生并通过阻断 IFN-α 产生受体来测定 IFN-α 丢失的影响发信号。接下来，我们通过对 CIITA 等位基因破坏的小鼠进行肌肉损伤研究，试图了解 CIITA 对肌肉修复的贡献。最后，我们试图确定 CIITA 是否是 IFN-α 的介体？和成肌细胞中的 STAT1 信号传导。我们的初步数据表明 CIITA 及其对肌生成素的抑制是 IFN-α 的许多作用的原因。和肌原细胞上的 STAT1。我们将尝试通过确认 STAT1 激活成肌细胞中的 CIITA 并使用 STAT1 抑制剂来确认 IFN-α 后抗分化作用的丧失来支持我们的假设。刺激。然后我们将尝试通过过度表达 CIITA 来挽救这种效应。我们还将检测 IFN-？ Myog-/- 成肌细胞中的影响以确定是否需要肌细胞生成素来介导 IFN-？介导肌肉特定目标的下调。公众健康相关性：骨骼肌能够在一生中生长和修复。当肌肉因年龄或肌营养不良而无法修复时，就会导致运动能力丧失，最终导致死亡。该提案旨在描述肌肉损伤炎症反应诱导的信号传导与可修复肌肉纤维的因子之间的新联系。我们在骨骼肌细胞中发现了一种因子，它既能对炎症释放的信号做出反应，又能抑制重建肌肉最后步骤所需的特定因子的活性。我们建议该系统在进行最终修复步骤之前为肌肉提供启动修复所需的时间。该提案旨在进一步表征肌肉细胞中的这一因子，并确定其在骨骼肌分化和修复中的细胞作用。这项工作对于理解骨骼肌在受伤后如何自我修复具有重要意义，并且可能能够为如何在衰老或疾病的情况下刺激肌肉再生提供新的见解。