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，尽管诸如下丘脑-垂体-肾上腺抑制、代谢综合征和骨质疏松症等副作用限制了其使用。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具有更高疗效/风险比的哮喘治疗方法。我们最近发现，GR有八种不同的翻译异构体，在广泛的细胞类型中表达变化。这些GR亚型对基因表达有截然不同的影响。我们假设选择性GR翻译异构体介导糖皮质激素诱导的细胞凋亡的不同敏感性，并调节在哮喘中至关重要的T细胞和树突状细胞亚群中的细胞特异性炎症反应。我们提出炎症刺激通过翻译机制选择性调节GR亚型。为了验证这些假设，我们将检查从小鼠哮喘模型中获得的原代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的研究将在小鼠哮喘模型中确定GR翻译异构体在辅助性T细胞中的身份和功能，辅助性T细胞是对糖皮质激素诱导的细胞凋亡具有抗性的敏感和调节性T细胞（Tregs）。我们的初步数据表明，在成骨细胞和T细胞模型系统中，辅助性T细胞主要表达促凋亡的GR-A亚型，而Tregs主要表达不能诱导凋亡的GR-D亚型。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。Aim 2的研究将确定未成熟和成熟树突状细胞中GR翻译异构体的身份和功能，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在成熟后从GR-D亚型转换为表达GR-A亚型。GR异构体在未成熟（不敏感）和成熟（敏感）树突状细胞不同的糖皮质激素敏感性中的作用以及在成熟阶段的特定功能将被确定。Aim 3的研究将确定翻译机制在调控选择性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mRNA产生的。基于我们的初步结果，我们将重点研究真核起始因子在GR亚型选择性表达中的作用。这些研究将提高我们对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异构体有望介导细胞对糖皮质激素的特异性敏感性和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。公共卫生相关性：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，并开发新的糖皮质激素药物，提高哮喘治疗的获益/风险比。本研究将阐明T细胞和树突状细胞中糖皮质激素受体翻译异构体的细胞特异性表达模式、功能和调控，这是哮喘的关键。这一发现可能会提高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治疗哮喘和其他炎症性疾病开辟新的途径。