Glucocorticoid receptor translational isoforms in asthma

哮喘中的糖皮质激素受体翻译亚型

• 批准号: 7838659
• 负责人: NICK LU
• 金额: $ 25.29万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7838659
• 关键词: Adrenal Glands; Adverse effects; Animals; Anti-Inflammatory Agents; Anti-inflammatory; Antigens; Apoptosis; Asthma; Biological Models; Bone Marrow; CD4 Positive T Lymphocytes; Cell Line; Cell model; Cells; Complement component C1s; Data; Dendritic Cells; Development; Disease; Drug Delivery Systems; Drug or chemical Tissue Distribution; Eukaryotic Initiation Factors; Gene Expression; Gene Expression Regulation; Glucocorticoid Receptor; Glucocorticoid-induced apoptosis; Glucocorticoids; Goals; Helper-Inducer T-Lymphocyte; Immune; Immunity; Immunosuppressive Agents; Individual; Inflammation; Inflammatory; Inflammatory Response; Informatics; Ligands; Lipopolysaccharides; Lung; Mediastinal lymph node group; Mediating; Messenger RNA; Metabolic syndrome; Modeling; Mus; Odds Ratio; Osteoblasts; Osteoporosis; Pattern; Pharmaceutical Preparations; Pituitary Gland; Play; Production; Protein Isoforms; Regulation; Resistance; Role; Scanning; Sentinel; Staging; Stimulus; T-Lymphocyte; T-Lymphocyte Subsets; Testing; Toll-like receptors; Translations; Work; airborne allergen; base; cell type; cytokine; design; improved; killings; pathogen; public health relevance; respiratory; risk benefit ratio; selective expression; stable cell line; therapy development; translation factor; uptake

DESCRIPTION (provided by applicant): Glucocorticoids are indispensable in the treatment of asthma and other inflammatory diseases although side effects such as hypothalamo-pituitary-adrenal suppression, metabolic syndrome, and osteoporosis limit their use. Our goal is to understand the mechanisms by which the glucocorticoid receptor (GR) mediates cell-specific functions, as this information may be useful in the development of treatments for asthma with improved efficacy/risk ratios. We have recently discovered that the GR has eight distinct translational isoforms expressed variably in a wide range of cell types. These GR isoforms have profoundly different effects on gene expression. We hypothesize that selective GR translational isoforms mediate distinct sensitivities to glucocorticoid-induced apoptosis and regulate cell-specific inflammatory responses in T cell and dendritic cell subsets that are crucial in asthma. We propose that inflammatory stimuli selectively regulate GR isoforms via translational mechanisms. To test these hypotheses, we will examine primary T cells and dendritic cells obtained from a murine asthma model, cell lines expressing individual GR isoforms, and bone marrow-derived dendritic cells. Studies in Aim 1 will determine in a murine asthma model the identity and function of GR translational isoforms in helper T cells that are sensitive and regulatory T cells (Tregs) that are resistant to glucocorticoid-induced apoptosis. Our preliminary data indicate that helper T cells express predominantly the proapoptotic GR-A isoform whereas Tregs have predominantly the GR-D isoforms that are incapable of inducing apoptosis in osteoblast and T cell model systems. We will determine the role of selective GR isoforms in T cell subset-specific functions and glucocorticoid sensitivities. Studies in Aim 2 will determine the identity and function of GR translational isoforms in immature and mature dendritic cells that also have distinct sensitivities to glucocorticoid-induced apoptosis. Our preliminary data indicate that immature dendritic cells switch from the GR-D isoforms to expressing the GR-A isoform after maturation. The role of GR isoforms in distinct glucocorticoid sensitivities of immature (insensitive) and mature (sensitive) dendritic cells and in maturational-stage specific functions will be determined. Studies in Aim 3 will determine the role of translation machinery in regulating the expression of selective GR isoforms. Our previous studies indicate that the GR translational isoforms are produced from a single species of mRNA via ribosomal leaky scanning and ribosomal shunting. Based on our preliminary results, we will focus on the role of eukaryotic initiation factors in selective expression of GR isoforms. These studies will improve our understanding of the cell-specific actions of GR translational isoforms in asthma. Selective GR isoforms are anticipated to mediate cell-specific sensitivities to glucocorticoids and regulate cell- specific functions. In addition, these studies may provide a basis for the development of anti- inflammatory drugs targeting or altering the expression of selective GR isoforms. PUBLIC HEALTH RELEVANCE: Our long-term goal is to understand the mechanisms underlying the cell-specific action of glucocorticoids and to develop new glucocorticoid drugs with improved benefit/risk ratios for the treatment of asthma. The studies in this proposal will elucidate the cell-specific expression pattern, function, and regulation of glucocorticoid receptor translational isoforms in T cells and dendritic cells that are pivotal in asthma. The findings from this proposal may improve our understanding of the mechanisms of action of glucocorticoids and open new avenues for designing safer glucocorticoids for the treatment of asthma and other inflammatory diseases.

描述（由申请人提供）：糖皮质激素在治疗哮喘和其他炎症性疾病中是必不可少的，尽管副作用，例如下丘脑 - 垂体 - 辅助 - 肾上腺抑制，代谢综合征和骨质疏松症限制了其使用。我们的目标是了解糖皮质激素受体（GR）介导细胞特异性功能的机制，因为此信息可能在开发哮喘治疗疗法的疗效/风险比的治疗方法中很有用。我们最近发现，GR具有八种不同的转化同工型，在各种细胞类型中都具有可变的表达。这些GR的同工型对基因表达具有明显不同的影响。我们假设选择性GR转化同工型介导了对糖皮质激素诱导的凋亡的不同敏感性，并调节T细胞和树突状细胞亚群中至关重要的细胞特异性炎症反应，这在哮喘中至关重要。我们建议炎症刺激通过翻译机制有选择地调节GR同工型。为了检验这些假设，我们将检查从鼠哮喘模型获得的原代T细胞和树突状细胞，表达单个GR亚型的细胞系以及骨髓来源的树突状细胞。 AIM 1中的研究将在鼠哮喘模型中确定辅助和调节性T细胞（Tregs）在辅助性T细胞中的GR转化同工型的身份和功能，对糖皮质激素诱导的细胞凋亡具有抗性。我们的初步数据表明，辅助T细胞主要表达促凋亡的GR-A同工型，而Tregs主要具有无法在成骨细胞和T细胞模型系统中诱导凋亡的GR-D同工型。我们将确定选择性GR同工型在T细胞亚群特异性功能和糖皮质激素敏感性中的作用。 AIM 2中的研究将确定在未成熟和成熟的树突状细胞中GR转化同工型的同一性和功能，这些树突状细胞对糖皮质激素诱导的凋亡也具有不同的敏感性。我们的初步数据表明，未成熟的树突状细胞从GR-D同工型转换为成熟后表达GR-A同工型。 GR同工型在未成熟（不敏感）和成熟（敏感的）树突状细胞以及成熟阶段特定功能中的不同糖皮质激素敏感性中的作用将得到确定。 AIM 3中的研究将确定翻译机制在调节选择性GR同工型表达中的作用。我们先前的研究表明，通过核糖体漏扫描和核糖体分流，从单个mRNA产生了GR转化同工型。根据我们的初步结果，我们将重点关注真核起始因子在GR同工型选择性表达中的作用。这些研究将提高我们对哮喘中GR转化同工型的细胞特异性作用的理解。选择性GR同工型预计会介导细胞特异性对糖皮质激素的敏感性并调节细胞特异性功能。此外，这些研究可能为开发靶向或改变选择性GR同工型表达的抗炎性药物的发展提供基础。公共卫生相关性：我们的长期目标是了解糖皮质激素的细胞特异性作用的基础机制，并开发新的糖皮质激素药物，并改善了治疗哮喘的益处/风险比率。该提案中的研究将阐明细胞特异性的表达模式，功能和调节T细胞和树突状细胞中糖皮质激素受体翻译同工型的细胞表达模式，和调节，这些细胞和树突状细胞在哮喘中是关键的。该提案的发现可能会提高我们对糖皮质激素作用机理的理解，并开放新的途径，以设计更安全的糖皮质激素治疗哮喘和其他炎症性疾病。