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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）：骨骼肌具有非凡的生长和修复能力。骨骼肌再生中的缺陷有助于正常的人类衰老和肌营养不良。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人类生物学至关重要。我们认为，我们已经确定了一个新的连接炎症反应和骨骼肌重塑介导的肌源性调节家族（MRF）。炎症反应在启动骨骼肌再生中起重要作用。参与炎症反应的细胞因子之一是抗纤维化药物干扰素γ（IFN-？）。IFN-？对肌生成具有复杂的作用，但对于体内有效的肌肉再生是必需的。我们已经确定了II类反式激活因子，CIITA，作为一个因素，与肌细胞生成素，MRF介导的终端分化。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既作为共激活因子又作为共抑制因子。CIITA被IFN-？通过JAK/STAT途径，导致STAT 1直接激活CIITA。CIITA有组成和IFN-？在细胞中的作用。我们已经证实CIITA在C2 C12成肌细胞系中表达，并显示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-？刺激，IFN-？CIITA的过表达下调肌肉特异性基因的表达，抑制分化。因此，我们假设CIITA是IFN-？骨骼肌细胞中的信号。在这个提议中，我们试图了解CIITA如何有助于肌肉发生和肌肉修复。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度表达和敲除研究证实CIITA的抗分化作用，来扩展我们目前关于CIITA在成肌细胞中作用的工作。我们还计划启动研究的作用，干扰素？在正常的肌生成的特点水平的干扰素-？产生的成肌细胞和阻断干扰素-？受体，以测定IFN-？信号接下来，我们通过对CIITA等位基因被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-？和成肌细胞中的STAT 1信号。我们的初步数据表明，CIITA和它的抑制肌细胞生成素是负责许多IFN-？和STAT 1对肌细胞的作用。我们将试图支持我们的假设，证实STAT 1激活CIITA成肌细胞和使用STAT 1抑制剂，以确认损失的抗分化作用后IFN-？刺激.然后，我们将尝试通过过度表达CIITA来挽救这种效果。我们还将检测IFN-？在肌细胞-/-成肌细胞的影响，以确定是否需要肌细胞生成素介导的IFN-？介导的肌肉特异性靶点下调。公共卫生相关性：骨骼肌能够在一生中生长和修复。当肌肉由于年龄或肌肉萎缩症而无法修复时，这会导致失去移动能力并最终导致死亡。该提案旨在描述肌肉损伤炎症反应诱导的信号传导与修复肌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，它既能响应炎症释放的信号，又能抑制重建肌肉的最后步骤所需的特定因子的活性。我们建议，这个系统给肌肉的时间，它需要启动修复之前，致力于修复的最后步骤。该提案旨在进一步表征肌细胞中的该因子，并确定其在骨骼肌分化和修复中的细胞作用。这项工作对理解骨骼肌在受伤后如何自我修复具有重要意义，并可能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。