Acute myocardial infarction (AMI) represents the acute manifestation of coronary artery disease. In recent years, microRNAs (miRNAs) have been extensively studied in AMI. This study focused on the role of miR-431-5p in AMI and its effect on cardiomyocyte apoptosis after AMI. The expression of miR-431-5p was analyzed by quantitative real-time PCR (qRT-PCR). By interfering with miR-431-5p in hypoxiareoxygenation (H/R)-induced HL-1 cardiomyocytes, the effect of miR-431-5p on cardiomyocyte apoptosis after AMI was examined. The interaction between miR-431-5p and selenoprotein T (SELT) mRNA was verified by dual-luciferase reporter assay. Cell apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and flow cytometry. Cell viability was examined by 3-(4,5)- dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay. The results of qRT-PCR showed that the expression of miR-431-5p in AMI myocardial tissues and H/R-induced HL-1 cardiomyocytes was significantly increased. After interfering with miR-431-5p, the expression of SELT in HL-1 cells was up-regulated, cell apoptosis was decreased, cell viability was increased, and lactate dehydrogenase (LDH) activity was decreased. The dual-luciferase reporter assay confirmed the targeting relationship between miR-431-5p and SELT1 3’ untranslated region (UTR). In H/R-induced HL-1 cells, the simultaneous silencing of SELT and miR-431-5p resulted in a decrease of Bcl-2 expression, an increase of Bax expression, and an increase of cleaved-caspase 3 expression compared with silencing miR-431-5p alone. Also, cell viability was decreased, while LDH activity was increased by the simultaneous silencing of SELT and miR-431-5p. Interfering miR-431-5p protected cardiomyocytes from AMI injury via restoring the expression of SELT, providing new ideas for the treatment of AMI.
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.
Abnormal accumulation of lymphoblasts in the blood and bone marrow is the main characteristic of acute lymphoblastic leukaemia (ALL). Glucocorticoids are effective drugs for ALL, while glucocorticoid resistance is an obstacle to ALL therapy. MicroRNAs (miRNAs) are implicated in the drug resistance and modulate the response of ALL to glucocorticoids. The role of miR-503 in glucocorticoid sensitivity of ALL was investigated in this study. Firstly, T-leukaemic cells were isolated from patients with ALL. The human ALL cell line (CCRF/CEM) was incubated with dexamethasone to establish a glucocorticoid- resistant ALL cell line (CCRF/CEM-R). Data from MTT showed that IC50 (50% inhibitory concentration) of dexamethasone in T-leukaemic cells isolated from glucocorticoid-resistant ALL patients or CCRF/CEM-R was increased compared with IC50 in T-leukaemic cells isolated from glucocorticoid- sensitive ALL patients or CCRF/CEM. MiR- 503 was down-regulated in glucocorticoid-resistant leukaemic cells and CCRF/CEM-R. Secondly, overexpression of miR-503 sensitized CCRF/CEM-R to dexamethasone. Moreover, over-expression of miR- 503 also promoted the sensitivity of ALL cells to dexamethasone. Thirdly, miR-503 bound to WNT3A mRNA and negatively regulated the expression of WNT3A. Over-expression of miR-503 reduced protein expression of nuclear β-catenin, and over-expression of WNT3A attenuated the miR-503 overexpression- induced decrease in nuclear β-catenin. Lastly, the over-expression of miR-503-induced increased sensitivity of ALL-resistant cells and CCRF/ CEM-R to dexamethasone was attenuated by overexpression of WNT3A. In conclusion, miR-503 targeted WNT3A mRNA to sensitize ALL cells to glucocorticoids through inactivation of the Wnt/β-catenin pathway.