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核因子-κB、p38 MAPK 和糖皮质激素受体信号通路的相互作用协同诱导肺上皮细胞中功能性 TLR2 的表达。

Interplay between nuclear factor-κB, p38 MAPK, and glucocorticoid receptor signaling synergistically induces functional TLR2 in lung epithelial cells.

机构信息

Department of Physiology & Pharmacology and Airways Inflammation Research Group, Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.

Department of Medicine and Airways Inflammation Research Group, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada.

出版信息

J Biol Chem. 2022 Apr;298(4):101747. doi: 10.1016/j.jbc.2022.101747. Epub 2022 Feb 19.

Abstract

While glucocorticoids act via the glucocorticoid receptor (GR; NR3C1) to reduce the expression of many inflammatory genes, repression is not an invariable outcome. Here, we explore synergy occurring between synthetic glucocorticoids (dexamethasone and budesonide) and proinflammatory cytokines (IL1B and TNF) on the expression of the toll-like receptor 2 (TLR2). This effect is observed in epithelial cell lines and both undifferentiated and differentiated primary human bronchial epithelial cells (pHBECs). In A549 cells, IL1B-plus-glucocorticoid-induced TLR2 expression required nuclear factor (NF)-κB and GR. Likewise, in A549 cells, BEAS-2B cells, and pHBECs, chromatin immunoprecipitation identified GR- and NF-κB/p65-binding regions ∼32 kb (R1) and ∼7.3 kb (R2) upstream of the TLR2 gene. Treatment of BEAS-2B cells with TNF or/and dexamethasone followed by global run-on sequencing confirmed transcriptional activity at these regions. Furthermore, cloning R1 or R2 into luciferase reporters revealed transcriptional activation by budesonide or IL1B, respectively, while R1+R2 juxtaposition enabled synergistic activation by IL1B and budesonide. In addition, small-molecule inhibitors and siRNA knockdown showed p38α MAPK to negatively regulate both IL1B-induced TLR2 expression and R1+R2 reporter activity. Finally, agonism of IL1B-plus-dexamethasone-induced TLR2 in A549 cells and pHBECs stimulated NF-κB- and interferon regulatory factor-dependent reporter activity and chemokine release. We conclude that glucocorticoid-plus-cytokine-driven synergy at TLR2 involves GR and NF-κB acting via specific enhancer regions, which combined with the inhibition of p38α MAPK promotes TLR2 expression. Subsequent inflammatory effects that occur following TLR2 agonism may be pertinent in severe neutrophilic asthma or chronic obstructive pulmonary disease, where glucocorticoid-based therapies are less efficacious.

摘要

虽然糖皮质激素通过糖皮质激素受体(GR;NR3C1)来减少许多炎症基因的表达,但抑制并不是不变的结果。在这里,我们探讨了合成糖皮质激素(地塞米松和布地奈德)和促炎细胞因子(IL1B 和 TNF)在 Toll 样受体 2(TLR2)表达上的协同作用。这种效应在上皮细胞系以及未分化和分化的原代人支气管上皮细胞(pHBECs)中都观察到。在 A549 细胞中,IL1B 加糖皮质激素诱导的 TLR2 表达需要核因子(NF)-κB 和 GR。同样,在 A549 细胞、BEAS-2B 细胞和 pHBECs 中,染色质免疫沉淀鉴定了 TLR2 基因上游约 32 kb(R1)和 7.3 kb(R2)处的 GR 和 NF-κB/p65 结合区域。用 TNF 或/和地塞米松处理 BEAS-2B 细胞,然后进行全局运行测序,证实了这些区域的转录活性。此外,将 R1 或 R2 克隆到荧光素酶报告基因中,分别显示出布地奈德或 IL1B 的转录激活,而 R1+R2 并列使 IL1B 和布地奈德能够协同激活。此外,小分子抑制剂和 siRNA 敲低表明 p38α MAPK 负调节 IL1B 诱导的 TLR2 表达和 R1+R2 报告基因活性。最后,A549 细胞和 pHBECs 中 IL1B 加地塞米松诱导的 TLR2 的激动作用刺激了 NF-κB 和干扰素调节因子依赖性报告基因活性和趋化因子释放。我们得出结论,TLR2 上的糖皮质激素加细胞因子驱动的协同作用涉及 GR 和 NF-κB 通过特定的增强子区域发挥作用,与 p38α MAPK 的抑制相结合,促进 TLR2 的表达。随后 TLR2 激动引起的炎症效应可能与严重嗜中性哮喘或慢性阻塞性肺疾病有关,在这些疾病中,基于糖皮质激素的治疗效果较差。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a2fe/8942839/54e594ec9273/gr1.jpg

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