Transcriptional inhibition of miR-486-3p by BCL6 upregulates Snail and induces epithelial–mesenchymal transition during radiation-induced pulmonary fibrosis

Abstract

Background Ionizing radiation (IR) can induce pulmonary fibrosis by causing epithelial mesenchymal transition (EMT), but the exact mechanism has not been elucidated. To investigate the molecular mechanism of how radiation induces pulmonary fibrosis by altering miR-486-3p content and thus inducing EMT. Methods The changes of miR-486-3p in cells after irradiation were detected by RT-qPCR. Western blot was used to detect the changes of cellular epithelial marker protein E-cadherin, mesenchymal marker N-cadherin, Vimentin and other proteins. The target gene of miR-486-3p was predicted by bioinformatics method and the binding site was verified by dual luciferase reporter system. In vivo experiments, adeno-associated virus (AAV) was used to carry miR-486-3p mimic to lung. Radiation-induced pulmonary fibrosis (RIPF) model was constructed by 25Gy60Co γ-rays. The structural changes of mouse lung were observed by HE and Masson staining. The expression of relevant proteins in mice was detected by immunohistochemistry. Results IR could decrease the miR-486-3p levels in vitro and in vivo, and that effect was closely correlated to the occurrence of RIPF. The expression of Snail, which induces EMT, was shown to be restrained by miR-486-3p. Therefore, knockdown of Snail blocked the EMT process induced by radiation or knockdown of miR-486-3p. In addition, the molecular mechanism underlying the IR-induced miRNA level reduction was explored. The increased in BCL6 could inhibit the formation of pri-miR-486-3p, thereby reducing the levels of miR-486-3p in the alveolar epithelial cells, which would otherwise promote EMT and contribute to RIPF by targeting Snail. Conclusion IR can exacerbate RIPF in mice by activating the transcription factor BCL6, which inhibits the transcription of miR-486-3p and decreases its content, which in turn increases the content of the target gene slug and triggers EMT.

DNA‐PKcs/AKT1 inhibits epithelial–mesenchymal transition during radiation‐induced pulmonary fibrosis by inducing ubiquitination and degradation of Twist1

“…31,32 Additionally, epigenetic processes such as noncoding RNA and DNA methylation also play a critical role in IR-induced EMT. [33][34][35][36][37][38] Although the mechanism through which radiation induces EMT has been widely discussed, the role of DNA-PKcs in EMT remains controversial. 39,40 Our present study showed that DNA-PKcs deletion can promote EMT in lung epithelial cells in vitro and has a synergistic effect with IR.…”

“…According to previous studies, IR can induce EMT by activating the TGF‐β, extracellular signal‐regulated kinase (ERK) and nuclear factor‐kappa B (NF‐κB) signalling pathways or by directly promoting the expression of profibrotic transcription factors such as Snail, Twist and ZEB1 31,32 . Additionally, epigenetic processes such as noncoding RNA and DNA methylation also play a critical role in IR‐induced EMT 33–38 . Although the mechanism through which radiation induces EMT has been widely discussed, the role of DNA‐PKcs in EMT remains controversial 39,40 .…”

Identification of circRNA-miRNA-mRNA network as biomarkers for interstitial cystitis/bladder pain syndrome

“…Our qPCR results indicated a statistically significant increase in hsa-miR-486-3P and hsa-miR-20b-5P, which is consistent with the sequencing results, and their stability and tissue specificity suggest their potential as biomarkers for IC/BPS [ 20 ]. Interestingly, hsa-miR-486-3p has also been implicated in epithelial-mesenchymal transformation in pulmonary fibrosis, which could be a contributing factor in the pathogenesis of IC/BPS [ 22 ]. Their findings highlight the importance of miRNAs in the development of IC/BPS and suggest new avenues for research.…”

Tissue fibrosis induced by radiotherapy: current understanding of the molecular mechanisms, diagnosis and therapeutic advances

“…This also leads to the expression of Slug (Snail2), a key gene in EMT, which allows the exacerbation of pulmonary fibrosis after radiation exposure [ 194 ]. Moreover, ionizing radiation stimulation activates B-cell lymphoma 6 protein (BCL6) from the BTB/POZ zinc finger protein family, which inhibits the expression of downstream miR-486-3p and increases the expression of Snail, thus promoting EMT [ 195 ]. According to research, radiation exposure leads to a reduction in miR-155-5p levels in alveolar epithelial cells.…”