Department of Otolaryngology Head and Neck Surgery, Shaanxi Provincial People's Hospital, Xi'an 710068, Shaanxi, PR China.
Department of Medical Imaging, Chang'an Hospital, Xi'an 710016, Shaanxi, PR China.
Life Sci. 2021 Jun 15;275:119356. doi: 10.1016/j.lfs.2021.119356. Epub 2021 Mar 15.
Growth and differentiation factor 15 (GDF15) is a stress-related factor, which implicated in various diseases. This study aimed to investigate the role of GDF15 in LPS-mediated inflammation and to explore the potential underlying molecular mechanisms in human nasal epithelial cells (HNEpCs).
HNEpCs were treated with LPS. GDF15 loss-of-function and gain-of-function experiments were performed. The expression of GDF15 by quantitative real-time PCR (RT-qPCR). The mRNA levels and secretion of inflammatory cytokines and MUC5AC were assessed by RT-qPCR and ELISA kits. LY294002 (PI3K inhibitor) and 740Y-P (PI3K agonist) were utilized to interfere with PI3k/Akt pathway. The relationship between GDF15 and ATF4 was identified by chromatin immunoprecipitation (ChIP) and luciferase reporter assay.
We observed that LPS triggered GDF15 expression. GDF15 ablation reduced the mRNA levels and secretion of inflammatory cytokines. GDF15 silencing led to the reduction of the MUC5AC mRNA level, protein level and secretion in response to LPS. Enhanced expression of GDF15 showed the opposite results. Furthermore, we found that GDF15 deficiency inhibited activation of the PI3K/Akt pathway, LY294002 treatment further enhanced the role of GDF15 suppression in inflammation and MUC5AC expression, while 740Y-P administration partly reversed the biological activities of GDF15 silencing. ATF4 could bind to the promoter of GDF15 and positively regulate GDF15 expression. Depression of ATF4 diminished the secretion of inflammatory cytokines and MUC5AC via regulation of GDF15.
Our data suggest that GDF15 is regulated by ATF4 and suppresses LPS-induced inflammation and MUC5AC in human nasal epithelial cells through the PI3K/Akt pathway.
生长分化因子 15（GDF15）是一种与应激相关的因子，与多种疾病有关。本研究旨在探讨 GDF15 在 LPS 介导的炎症中的作用，并探索其在人鼻腔上皮细胞（HNEpCs）中的潜在分子机制。
用 LPS 处理 HNEpCs。进行 GDF15 功能丧失和功能获得实验。用定量实时 PCR（RT-qPCR）检测 GDF15 的表达。用 RT-qPCR 和 ELISA 试剂盒检测炎症细胞因子和 MUC5AC 的 mRNA 水平和分泌。用 LY294002（PI3K 抑制剂）和 740Y-P（PI3K 激动剂）干扰 PI3k/Akt 通路。用染色质免疫沉淀（ChIP）和荧光素酶报告基因检测鉴定 GDF15 与 ATF4 的关系。
我们观察到 LPS 触发了 GDF15 的表达。GDF15 缺失减少了炎症细胞因子的 mRNA 水平和分泌。GDF15 沉默导致 LPS 反应中 MUC5AC 的 mRNA 水平、蛋白水平和分泌减少。增强 GDF15 的表达则显示出相反的结果。此外，我们发现 GDF15 缺乏抑制了 PI3K/Akt 通路的激活，LY294002 处理进一步增强了 GDF15 抑制炎症和 MUC5AC 表达的作用，而 740Y-P 给药部分逆转了 GDF15 沉默的生物学活性。ATF4 可以结合 GDF15 的启动子并正向调节 GDF15 的表达。下调 ATF4 通过调节 GDF15 减少了炎症细胞因子和 MUC5AC 的分泌。
我们的数据表明，GDF15 受 ATF4 调节，通过 PI3K/Akt 通路抑制 LPS 诱导的人鼻腔上皮细胞炎症和 MUC5AC。
