MicroRNA-744 Inhibits Proliferation of Bronchial Epithelial Cells by Regulating Smad3 Pathway via Targeting Transforming Growth Factor-β1 (TGF-β1) in Severe Asthma

Abstract

Background Bronchial epithelial cells proliferation plays a pivotal role in airway remodeling in children with severe asthma. MicroRNAs (miRNAs) have gained great attention for many diseases, including asthma. The purpose of this study was to explore the mechanisms that underlie miR-744 modulating bronchial epithelial cells proliferation in severe asthma in children. Material/Methods Bronchial epithelial cells were isolated from bronchial biopsies of normal controls and asthmatic subjects. miR-744 and transforming growth factor-β1 (TGF-β1) expressions were measured by quantitative reverse transcription PCR (qRT-PCR). Proliferating cell nuclear antigen (PCNA), phosphorylation or total of mothers against decapentaplegic homolog3 (Smad3) and production of Smad anchor for receptor activation (SARA) were measured via Western blot analysis. A link between miR-744 and TGF-β1 was probed by luciferase activity and RNA immunoprecipitation. Cell proliferation was evaluated using the Cell Proliferation Assay Kit. Results Severe asthma showed a significantly elevated cell proliferation rate and reduced abundance of miR-744, which in turn inhibited cell proliferation of bronchial epithelial cells. In particular, TGF-β1 might be a candidate target of miR-744, and enrichment of miR-744 lowered the expression of TGF-β1 at mRNA and protein levels. Indeed, overexpression of miR-744 lowered the proliferation rate of bronchial epithelial cells via driving TGF-β1. Moreover, addition of miR-744 limited phosphorylation of Smad3 but reversed SARA protein abundance by regulating TGF-β1. Conclusions The presence of miR-744 repressed bronchial epithelial cells proliferation through mediating the Smad3 pathway by modulating TGF-β1, providing a promising therapeutic approach for epithelial function in severe asthma.

miRNAs in Lung Development and Diseases

“…Nonetheless, the following are studies that emerged in recent months. In severe asthmatic bronchial epithelial cells obtained from patients, the level of miR-744 was decreased compared to its expression in normal control cells [61]. miR-744 downregulated the mRNA and protein levels of TGFB1, and in TGF-β1-stimulated normal and severe asthmatic bronchial epithelial cells, miR-744 mimic decreased p-SMAD3 and also increased the protein level of SARA.…”

“…miR-744 downregulated the mRNA and protein levels of TGFB1, and in TGF-β1-stimulated normal and severe asthmatic bronchial epithelial cells, miR-744 mimic decreased p-SMAD3 and also increased the protein level of SARA. miR-744 decreased the proliferation of bronchial epithelial cells, suggesting the importance of the miRNA in epithelial functions in asthma [61]. miR-943-3p was shown to regulate the level of SFRP4 [62].…”

MiR-203a-3p regulates TGF-β1-induced epithelial–mesenchymal transition (EMT) in asthma by regulating Smad3 pathway through SIX1

“…Although asthma is commonly diagnosed in childhood, it occurs in all age groups [3]. Ra et al reported that there was no significant difference between the prevalence rate of the elderly (>65) and that of the young people (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) [4]. A lot of stimuli, including cold air and exercise, and other risk factors such as smoking, obesity and rhinitis contribute to asthma incidence [5][6][7].…”

“…It has been reported that dysregulation of the TGF-β1/Smad pathway is necessary for bronchial epithelial cell proliferation in asthma patients. TGF-β1 can initiate cellular response, inducing phosphorylation of Smad2/Smad3 [21]. In addition, miRNAs have been found to implicate in the regulation of TGF-β1/Smad pathway.…”

“…For instance, miR-485 overexpression suppressed cell proliferation and induced apoptosis of airway smooth muscle cells (ASMCs) through the Smurf2-mediated TGF-β/Smads signaling pathway in mice with chronic asthma [22]. MiR-744 repressed bronchial epithelial cell proliferation by regulating Smad3 via targeting TGF-β1 in severe asthma [21].…”