miR-519d-3p promotes TGFβ/smad mediated postoperative epidural scar formation via suppression of BAMBI

Abstract

To investigate the role of microRNA (miR)-519d-3p in postoperative epidural scar formation and its regulation of the bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI), miR- 519d-3p and BAMBI expression levels in the lumbar disc of patients who had undergone laminectomy were detected with reverse transcription-quantitative polymerase chain reaction and western blotting. The results demonstrated that miR-519d-3p expression was significantly increased, whereas BAMBI expression was sharply reduced in the lumbar discs of patients suffering from epidural scars. Subsequently, the miR- 519d-3p mimic was transfected into primary fibroblasts isolated from epidural scar tissues. Flow cytometric and Cell Countin Kit-8 analyses indicated that overexpression of miR- 519d-3p promoted the proliferation of fibroblasts, the production of tumor necrosis factor-α and interleukin (IL)-1α, and the expression of type I collagen (col I), α-smooth muscle actin (α-SMA) and fibronectin (FN). Downregulation of miR- 519d-3p by the miR- 519d-3p antagomir transfection had the opposite effect. Bioinformatics and luciferase reporter gene analyses demonstrated that BAMBI is a target gene of miR- 519d-3p: miR- 519d-3p directly binds to the 3'-untranslated region of BAMBI mRNA and suppressed BAMBI protein expression. Finally, the pcDNA-BAMBI vector and BAMBI small interfering RNA were respectively transfected into primary fibroblasts to overexpress and knockdown the BAMBI gene. It was demonstrated that BAMBI overexpression suppressed fibroblast proliferation, TNF-α and IL- 1α production, and the expression of col I, α-SMA and FN proteins, whereas, BAMBI knockdown had the opposite effect. In conclusion, it was noted that BAMBI is a target of miR- 519d-3p and miR- 519d-3p promotes transforming growth factor β/mothers against decapentaplegic homolog 9-mediated postoperative epidural scar formation via suppression of BAMBI.