Nur77: Novel Mechanistic Insights and Activation in COPD

通常由吸烟引起的慢性阻塞性肺疾病（COPD）的患病率正在上升 预计到本世纪中叶，它将成为全球死亡的主要原因。可用的治疗方法提供 只有短期的好处，并不能阻止COPD的无情发展。即使是戒烟后， 早期阶段，提供有限的益处。因此，迫切需要新的机械疗法来阻止进展。 needed. COPD的病理生理学包括支气管炎症和重塑，结合间隔病变， 炎症相关的氧化应激和蛋白酶分泌导致的破坏/肺气肿。 炎症驱动的气道上皮细胞（AEC）凋亡也被认为有助于气道炎症。 重塑基于有希望的初步发现，拟议的研究将测试新的假设， 孤儿核激素受体Nur 77的激动剂活化可能在COPD中具有有益作用。 初步研究结果显示，COPD患者的AEC和肺以及吸烟小鼠的肺 吸烟（CS）诱导COPD显示Nur 77表达显著下调。我们还发现Nur 77 敲除（KO）可加重小鼠CS诱导的炎症和肺损伤，提示 内源性Nur 77。我们测试了用经典的Nur 77激动剂胞菌素B和 发现它改善了CS诱导的小鼠肺损伤和炎症，这使我们假设Nur 77 激动剂可用于COPD治疗。我们的计算机研究结果表明，Nur 77表现出双重（经典和 交替的）配体结合位点。尚未确定替代位点配体，但为了评估任何潜在的 激活它的有益效果，我们使用计算机建模来鉴定一种新的化合物， 证明与Nur 77替代位点结合，并发现它是激活Nur 77的激动剂 转录活性比胞孢素B更有效。CS提取物在体外引起AEC和II型 肺EC变得凋亡，这是一种可能导致COPD的途径。Nur 77本地化到 线粒体是已知的触发细胞凋亡，导致我们假设，CS提取物是诱导运动的线粒体， Nur 77从细胞核进入细胞质，再进入线粒体。我们的初步数据显示， 替代位点Nur 77激动剂通过将Nur 77锚定到 其靶向细胞核中的反应元件，从而改善肺EC的炎症和凋亡。基于 在这些新的发现，目的是：1：确定是否内源性抑制核和总的 Nur 77在COPD中的活性促进了疾病的进展和严重程度。2：测试是否激活Nur 77 改善COPD的严重程度和进展及其促成的肺EC凋亡。我们将实现这些目标 目的是用我们的新型有效的Nur 77体外治疗健康对照和COPD患者的人AEC 激动剂，并测试其在小鼠±转基因整体或AEC特异性Nur 77缺失中的作用，在标准CS- 诱导的小鼠COPD模型。结果将阐明受体Nur 77在COPD中的保护作用， 可能将其确定为一种有前途的新的治疗靶点，用于治疗广泛的致命疾病。

Chronic obstructive pulmonary disease (COPD), usually caused by cigarette smoking, is rising in prevalence and is predicted to become the leading cause of death worldwide by mid-century. Available treatments provide only short-term benefit, and fail to stop COPD’s inexorable progression. Even smoking cessation, after the earliest stages, provides limited benefit. New mechanistic therapies to halt progression are thus urgently needed. COPD pathophysiology includes bronchial inflammation and remodeling, combined with septal destruction/emphysema driven by inflammation-associated oxidative stress and protease secretion. Inflammation-driven apoptosis of airway epithelial cells (AECs) is also thought to contribute to airway remodeling. Based on promising preliminary findings, the proposed research will test the novel hypothesis that agonist activation of the orphan nuclear hormone receptor Nur77 may have beneficial effects in COPD. Preliminary findings revealed that AECs and lungs of COPD patients and also lungs of mice with cigarette smoke (CS)-induced COPD exhibit marked downregulation of Nur77 expression. We also found that Nur77 knockout (KO) exacerbates CS-induced inflammation and lung damage in mice, suggesting a protective role of endogenous Nur77. We tested the effects of treatment with the classical Nur77 agonist cytosporone B and found it ameliorated CS-induced lung damage and inflammation in mice, leading us to hypothesize that Nur77 agonists may be useful in COPD therapy. Our in silico findings show that Nur77 exhibits dual (classical and alternate) ligand binding sites. No alternate site ligand had been identified, but to assess any potential beneficial effects of activating it we used in silico modeling to identify a novel compound that in vitro studies demonstrated binds to the Nur77 alternate site, and found that it is an agonist that activates Nur77 transcriptional activity more effectively than cytosporone B. CS extract in vitro causes AECs and type ll pulmonary ECs to become apoptotic, a pathway that potentially contributes to COPD. Nur77 localization to mitochondria is known to trigger apoptosis, leading us to hypothesize that CS extract is inducing movement of Nur77 from the nucleus to cytoplasm and thence to the mitochondria. Our preliminary data show that our novel alternate site Nur77 agonist reverses such COPD-associated cytoplasmic localization by anchoring Nur77 to its target response elements in the nucleus, thus ameliorating inflammation and apoptosis of lung ECs. Based on these novel findings, the aims are to: 1: Determine whether endogenous suppression of nuclear and total Nur77 activity that occurs in COPD promotes disease progression and severity. 2: Test if activating Nur77 ameliorates COPD severity and progression and its contributing lung EC apoptosis. We will achieve these aims by treating human AECs of healthy controls and COPD patients in vitro with our novel, effective Nur77 agonist, and testing its effects in mice ± transgenic global or AEC-specific Nur77 deletion, in a standard CS- induced murine COPD model. The results will elucidate a protective role in COPD of the receptor Nur77, and may identify it as a promising new therapeutic target for specific agonists to treat a widespread fatal disease.