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（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不可或缺的，尽管其副作用如下丘脑-垂体-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，因为这些信息可能有助于开发提高疗效/风险比的哮喘治疗方法。我们最近发现 GR 有八种不同的翻译亚型，在多种细胞类型中表达不同。这些 GR 亚型对基因表达具有截然不同的影响。我们假设选择性 GR 翻译异构体介导对糖皮质激素诱导的细胞凋亡的不同敏感性，并调节 T 细胞和树突状细胞亚群中的细胞特异性炎症反应，这对哮喘至关重要。我们提出炎症刺激通过翻译机制选择性地调节 GR 亚型。为了检验这些假设，我们将检查从小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。目标 1 的研究将在小鼠哮喘模型中确定敏感辅助 T 细胞和对糖皮质激素诱导的细胞凋亡具有抵抗力的调节性 T 细胞 (Treg) 中 GR 翻译亚型的身份和功能。我们的初步数据表明，辅助性 T 细胞主要表达促凋亡 GR-A 亚型，而 Tregs 主要表达 GR-D 亚型，这些亚型无法在成骨细胞和 T 细胞模型系统中诱导细胞凋亡。我们将确定选择性 GR 亚型在 T 细胞亚群特异性功能和糖皮质激素敏感性中的作用。目标 2 中的研究将确定未成熟和成熟树突细胞中 GR 翻译亚型的身份和功能，这些细胞对糖皮质激素诱导的细胞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在成熟后从 GR-D 亚型转变为表达 GR-A 亚型。 GR亚型在未成熟（不敏感）和成熟（敏感）树突细胞的不同糖皮质激素敏感性以及成熟阶段特定功能中的作用将被确定。目标 3 的研究将确定翻译机制在调节选择性 GR 亚型表达中的作用。我们之前的研究表明，GR 翻译异构体是通过核糖体渗漏扫描和核糖体分流从单一种类的 mRNA 产生的。根据我们的初步结果，我们将重点关注真核起始因子在 GR 亚型选择性表达中的作用。这些研究将增进我们对 GR 翻译异构体在哮喘中的细胞特异性作用的理解。选择性 GR 亚型预计可介导细胞对糖皮质激素的特异性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亚型表达的抗炎药物提供基础。公共健康相关性：我们的长期目标是了解糖皮质激素细胞特异性作用的机制，并开发具有改善的哮喘治疗获益/风险比的新糖皮质激素药物。该提案中的研究将阐明 T 细胞和树突状细胞中糖皮质激素受体翻译亚型的细胞特异性表达模式、功能和调节，这些细胞在哮喘中至关重要。该提案的研究结果可能会增进我们对糖皮质激素作用机制的理解，并为设计更安全的糖皮质激素来治疗哮喘和其他炎症性疾病开辟新途径。