1National Heart and Lung Institute, Airway Disease Section, Imperial College London and Royal Brompton Hospital, Dovehouse St., London, SW3 6LY, UK.
FASEB J. 2013 Nov;27(11):4510-9. doi: 10.1096/fj.12-222604. Epub 2013 Aug 9.
Some patients with severe inflammatory disease fail to respond to glucocorticoids, and oxidative stress contributes to this insensitivity. Importin receptors are associated with nuclear translocation of the glucocorticoid receptor (GR), which is essential for glucocorticoid function. We hypothesized that importin-7 is central to GR nuclear translocation and glucocorticoid sensitivity. We investigated the effects of importin-7 siRNA on fluticasone propionate (FP)-induced GR nuclear localization and suppression of IL-1β-induced CXCL8 and the effects of hydrogen peroxide (H2O2) plus IL-1β costimulation on importin-7 expression, function, and glucocorticoid responsiveness in a human macrophagecell line (U937). H2O2 significantly reduced FP-induced GR nuclear localization (3.4±0.51- vs. 5.7±0.85-fold increase, P<0.05) and suppression of IL-1β-induced CXCL8 (62.3±2.3 vs. 85.1±7.0%, P<0.05). Knockdown of importin-7 by 38.4 ± 11.5% (compared with control siRNA) significantly reduced FP-mediated GR nuclear localization (3.5±0.5- vs. 5.7±0.85-fold increase, P<0.05) and suppression of IL-1β-induced CXCL8 expression (40.2±16.1 vs. 68.4±3.0%, P<0.05). H2O2 plus IL-1β had no direct effect on importin-7 but caused a significant loss (61.2±12.6% compared with baseline) of nuclear RanGTP, an essential cofactor for importin-7-mediated nuclear import of cargo proteins. The importin-7 complex is essential for glucocorticoid function, and the expression of its cofactor RanGTP is reduced during oxidative stress-induced glucocorticoid insensitivity.
一些患有严重炎症性疾病的患者对糖皮质激素治疗无反应，而氧化应激是导致这种不敏感性的原因之一。输入蛋白受体与糖皮质激素受体（GR）的核转位有关，这对于糖皮质激素的功能至关重要。我们假设输入蛋白-7 是 GR 核转位和糖皮质激素敏感性的核心。我们研究了输入蛋白-7 siRNA 对丙酸氟替卡松（FP）诱导的 GR 核定位以及抑制白细胞介素-1β（IL-1β）诱导的 CXCL8 的影响，以及过氧化氢（H2O2）和 IL-1β 共刺激对人巨噬细胞系（U937）中输入蛋白-7 表达、功能和糖皮质激素反应性的影响。H2O2 显著降低了 FP 诱导的 GR 核定位（增加 3.4±0.51-倍与 5.7±0.85-倍，P<0.05）和抑制 IL-1β 诱导的 CXCL8（减少 62.3±2.3%与 85.1±7.0%，P<0.05）。输入蛋白-7 的敲低 38.4 ± 11.5%（与对照 siRNA 相比）显著降低了 FP 介导的 GR 核定位（增加 3.5±0.5-倍与 5.7±0.85-倍，P<0.05）和抑制 IL-1β 诱导的 CXCL8 表达（减少 40.2±16.1%与 68.4±3.0%，P<0.05）。H2O2 和 IL-1β 对输入蛋白-7 没有直接作用，但显著降低了核 RanGTP 的表达（与基线相比减少 61.2±12.6%），核 RanGTP 是输入蛋白-7 介导的货物蛋白核输入的必需辅助因子。输入蛋白-7 复合物是糖皮质激素功能所必需的，其辅助因子 RanGTP 的表达在氧化应激诱导的糖皮质激素不敏感期间减少。
