Circulating miRNAs have been proposed as the effective diagnostic biomarkers for muscular fibrosis-associated diseases. However, circulating biomarkers for early diagnosis of contracture muscles are limited in gluteal muscle contracture (GMC) patients. Here we sought to explore the abnormally expressed miRNAs in plasma and contraction bands of GMC patients. The results showed miR-29a-3p expression in plasma and contraction bands tissue was significantly reduced in GMC patients compared with normal control. Cell viability and levels of proliferation-associated protein cyclin D1 and cyclindependent-kinase 2 (CDK2) were powerfully inhibited by miR-29a mimics and enhanced by miR-29a inhibitor compared with negative control. Furthermore, miR-29a mimics effectively impeded, while miR-29a inhibitor enhanced the expression of collagen I and collagen III, followed by the secretion of transforming growth factor β1 (TGF-β1), TGF-β3 and connective tissue growth factor (CTGF) in primary human contraction bands (CB) fibroblasts. The miR-29a-3p negatively regulated the expression of TGF-β1 through binding to the 3′ UTR region of SERPINH1 (encoding heat shock protein HSP47), but had no effect on Smad2 activity. The miR-29a-3p was inversely correlated with HSP47 in contraction bands tissue from GMC patients. Collectively, miR-29a was notably depressed and regulated cell viability and fibrosis by directly targeting HSP47 in GMC, which suggest that circulating miR-29a might be a potential biomarker for early diagnosis and provides a novel therapeutic target for GMC.
Gluteal muscle contracture (GMC) is a chronic fibrotic disease of gluteal muscles due to multiple etiologies. Emilin 1 plays a determinant role in fibers formation, but its role in the progression of GMC remains unclear. The present study was aimed to search for the predictive role and regulatory mechanism of Emilin 1 on GMC. Here, Protein and mRNA expression of Emilin 1 were decreased in GMC tissues compared to normal muscle tissues. Using the analysis of target prediction, Emilin 1 was observed to be a potential downstream sponge of miR-491-5p. In comparison to Emilin 1, miR-491-5p showed an aberrant elevation in GMC tissues, which was further proven to have a negative correlation with Emilin 1. The direct binding of miR-491-5p to Emilin 1 mRNA was confirmed by luciferase reporter gene assay, and miR-491-5p mimics inhibited, while miR-491-5p inhibitor promoted the protein expression and secretion of Emilin 1 in contraction bands (CB) fibroblasts. Additionally, miR-491-5p mimics promoted the expression of cyclin-dependent kinase 2 and cyclin D1 and the proliferation of CB fibroblasts, which could be reversed by Emilin 1 overexpression. Mechanistically, miR-491-5p mimics possibly activated transforming growth factor β1 (TGF-β1)/Smad3 signal cascade via binding to 3’-untranslated region of Emilin 1 mRNA, thereby promoting the progression of fibrosis of CB fibroblasts. Collectively, miR-491-5p inhibited Emilin 1 expression, and subsequently promoted CB fibroblasts proliferation and fibrosis via activating TGF-β1/Smad3 signal axis. MiR-491-5p might be a potentially effective biomarker for predicting GMC, providing a novel therapeutic strategy for GMC.