Glucocorticoids and glucocorticoid receptor translational isoforms

描述（由申请人提供）：糖皮质激素在炎症治疗中是不可或缺的，尽管它们不能有效治疗部分患者的中性粒细胞炎症。我们的长期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改善功效/风险比的抗炎治疗方法。该提案的目标是确定 GR 翻译异构体在中性粒细胞存活和功能中的作用。我们最近发现 GR 有八种翻译亚型，它们对基因表达和细胞功能具有截然不同的影响。我们假设选择性 GR 翻译异构体介导中性粒细胞对糖皮质激素诱导的细胞凋亡的抵抗。我们建议通过改变 GR 亚型来提高糖皮质激素在规避中性粒细胞炎症方面的功效。为了检验我们的假设，我们将检查慢病毒转导的人 CD34 细胞来源的中性粒细胞、小鼠骨髓来源的中性粒细胞和小鼠哮喘模型中的中性粒细胞。目标 1 的研究将确定 GR-A 亚型是否会增加中性粒细胞对糖皮质激素诱导的细胞凋亡的敏感性。我们发现初级中性粒细胞主要具有 GR-D 亚型。在多种白细胞中，GR-A 同种型（而非 GR-D）具有促凋亡作用。我们的初步数据还表明，视黄酸 (RA) 将中性粒细胞中的 GR-D 转变为 -A 亚型。如果表达 GR-A 的中性粒细胞对糖皮质激素敏感，则糖皮质激素可能有效抑制中性粒细胞气道炎症。目标 2 将确定异源核核糖核蛋白 L (hnRNP-L) 等翻译因子是否调节 GR 亚型的选择性表达和中性粒细胞的糖皮质激素敏感性。我们已经确定 hnRNP-L 是 GR-D 相关的翻译因子。早幼粒细胞 HL-60 细胞中 hnRNP-L 的敲低将 GR-D 转变为 -A 亚型。我们将测试中性粒细胞中 hnRNP-L 的敲低是否会改变中性粒细胞体外和体内糖皮质激素反应。这些研究将提高我们对 GR 翻译异构体在中性粒细胞炎症中作用的理解。 GR-A 亚型预计会增加糖皮质激素诱导中性粒细胞凋亡和抑制中性粒细胞炎症成分的能力。

DESCRIPTION (provided by applicant): Glucocorticoids are indispensable in the treatment of inflammation although they are not effective in treating neutrophilic inflammation in subsets of patients. Our long-term 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 anti-inflammatory treatments with improved efficacy/risk ratios. The goal of this proposal is to determine the role of GR translational isoforms in neutrophil survival and functions. We have recently discovered that the GR has eight translational isoforms that have profoundly different effects on gene expression and cell functions. We hypothesize that selective GR translational isoforms mediate neutrophil resistance to glucocorticoid-induced apoptosis. We propose to increase the efficacy of glucocorticoids in circumventing neutrophilic inflammation by altering GR isoforms. To test our hypotheses, we will examine lenti virus-transduced human CD34+ cell-derived neutrophils, mouse bone marrow-derived neutrophils, and neutrophils in a murine asthma model. Studies in Aim 1 will determine whether the GR-A isoform will increase the sensitivity of neutrophils to glucocorticoid induced-apoptosis. We have found that primary neutrophils have predominantly the GR-D isoforms. In multiple leukocytes, the GR-A, but not the GR-D, isoform is proapoptotic. Our preliminary data also show that retinoic acid (RA) switches the GR-D to the -A isoform in neutrophils. If GR-A expressing neutrophils are sensitive to glucocorticoids, glucocorticoids may be effective in inhibiting neutrophilic airway inflammation. Aim 2 will determine whether translation factors such as heterogenous nuclear ribonucleoprotein L (hnRNP-L) regulate the selective expression of GR isoforms and glucocorticoid sensitivity of neutrophils. We have identified hnRNP-L as a GR-D associated translation factor. Knockdown of hnRNP-L in promyelocytic HL-60 cells switched the GR-D to -A isoform. We will test whether knockdown of hnRNP-L in neutrophils alter neutrophil glucocorticoid responses in vitro and in vivo. These studies will improve our understanding of the role of GR translational isoforms in neutrophilc inflammation. The GR-A isoform is anticipated to increase the ability of glucocorticoids to induce neutrophil apoptosis and to inhibi components of neutrophilic inflammation.