Abstract
BackgroundSeveral studies have reported that hypoxia plays a pathological role in severe asthma and tissue fibrosis. Our previous study showed that hypoxia induces A disintegrin and metalloproteinase 17 (ADAM17) expression in human lung fibroblasts. Moreover, preadipocyte factor 1 (Pref-1) is cleaved by ADAM17, which participates in adipocyte differentiation. Furthermore, Pref1 overexpression is involved in tissue fibrosis including liver and heart. Extracellular signal-regulated kinase (ERK) could active downstram gene expression through polyoma enhancer activator 3 (PEA3) phosphorylation. Studies have demonstrated that PEA3 and activator protein 1 (AP-1) play crucial roles in lung fibrosis, and the Pref-1 promoter region contains PEA3 and AP-1 binding sites as predicted. However, the roles of ERK, PEA3, and AP-1 in hypoxia-stimulated Pref-1 expression in human lung fibroblasts remain unknown.MethodsThe protein expression in ovalbumin (OVA)-induced asthmatic mice was performed by immunohistochemistry and immunofluorescence. The protein expression or the mRNA level in human lung fibroblasts (WI-38) was detected by western blot or quantitative PCR. Small interfering (si) RNA was used to knockdown gene expression. The collaboration with PEA3 and c-Jun were determined by coimmunoprecipitation. Translocation of PEA3 from the cytosol to the nucleus was observed by immunocytochemistry. The binding ability of PEA3 and AP-1 to Pref-1 promoter was assessed by chromatin immunoprecipitation.ResultsPref-1 and hypoxia-inducible factor 1α (HIF-1α) were expressed in the lung sections of OVA-treated mice. Colocalization of PEA3 and Fibronectin was detected in lung sections from OVA-treated mice. Futhermore, Hypoxia induced Pref1 protein upregulation and mRNA expression in human lung fibroblasts (WI38 cells). In 60 confluent WI-38 cells, hypoxia up-regulated HIF-1α and Pref-1 protein expression. Moreover, PEA3 small interfering (si) RNA decreased the expression of hypoxia-induced Pref1 in WI38 cells. Hypoxia induced PEA3 phosphorylation, translocation of PEA3 from the cytosol to the nucleus, PEA3 recruitment and AP-1 binding to the Pref1 promoter region, and PEA3-luciferase activity. Additionally, hypoxia induced c-Jun-PEA3 complex formation. U0126 (an ERK inhibitor), curcumin (an AP1 inhibitor) or c-Jun siRNA downregulated hypoxia-induced Pref-1 expression.ConclusionsThese results implied that ERK, PEA3, and AP1 participate in hypoxiainduced Pref1 expression in human lung fibroblasts.
Highlights
Asthma is an allergic airway disease characterized by airway inflammation, epithelial apoptosis, and airway remodeling (Ahmad 2012; Hough 2020)
Pref‐1 and Hypoxia-inducible factor (HIF)‐1α expression were increased, and colocalization of polyoma enhancer activator 3 (PEA3) and fibronectin in lung sections from OVA‐treated mice To evaluate preadipocyte factor 1 (Pref-1) expression in severe asthma, we used a mouse model sensitized with the allergen OVA
In the OVAsensitized mouse model, hypoxia-inducible factor 1α (HIF-1α) was increased in the nuclear, and Pref-1 expression was detected in airway tissue by dual-label immunofluorescent staining (Fig. 1B, D, E)
Summary
Asthma is an allergic airway disease characterized by airway inflammation, epithelial apoptosis, and airway remodeling (Ahmad 2012; Hough 2020). Hypoxia could damage airway epithelium and promote lung inflammation through hypoxia-inducible factors (HIFs) (Ahmad 2012; Page et al 2021). Several studies have reported that hypoxia plays a pathological role in severe asthma and tissue fibro‐ sis. Our previous study showed that hypoxia induces A disintegrin and metalloproteinase 17 (ADAM17) expression in human lung fibroblasts. Studies have demonstrated that PEA3 and activator protein 1 (AP-1) play crucial roles in lung fibrosis, and the Pref-1 promoter region contains PEA3 and AP-1 binding sites as predicted. The roles of ERK, PEA3, and AP-1 in hypoxia-stimulated Pref-1 expression in human lung fibroblasts remain unknown
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.