Open Access

Role of miR-146a in human chondrocyte apoptosis in response to mechanical pressure injury in vitro

  • Authors:
    • Lei Jin
    • Jian Zhao
    • Wensen Jing
    • Shiju Yan
    • Xin Wang
    • Chun Xiao
    • Baoan Ma
  • View Affiliations

  • Published online on: June 16, 2014     https://doi.org/10.3892/ijmm.2014.1808
  • Pages: 451-463
  • Copyright: © Jin et al. This is an open access article distributed under the terms of Creative Commons Attribution License [CC BY_NC 3.0].

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Abstract

MicroRNA (miR)-146a is known to be overexpressed in osteoarthritis (OA). However, the role of miR-146a in OA has not yet been fully elucidated. In the present study, we applied mechanical pressure of 10 MPa to human chondrocytes for 60 min in order to investigate the expression of miR-146a and apoptosis following the mechanical pressure injury. Normal human chondrocytes were transfected with an miR-146a mimic or an inhibitor to regulate miR-146a expression. Potential target genes of miR-146a were predicted using bioinformatics. Moreover, luciferase reporter assay confirmed that Smad4 was a direct target of miR-146a. The expression levels of miR-146a, Smad4 and vascular endothelial growth factor (VEGF) were quantified by quantitative reverse transcription PCR and/or western blot analysis. The effects of miR-146a on apoptosis were detected by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) flow cytometry. The results indicated that mechanical pressure affected chondrocyte viability and induced the early apoptosis of chondrocytes. Mechanical pressure injury increased the expression levels of miR-146a and VEGF and decreased the levels of Smad4 in the chondrocytes. In the human chondrocytes, the upregulation of miR-146a induced apoptosis, upregulated VEGF expression and downregulated Smad4 expression. In addition, the knockdown of miR-146a reduced cell apoptosis, upregulated Smad4 expression and downregulated VEGF expression. Smad4 was identified as a direct target of miR-146a by harboring a miR‑146a binding sequence in the 3'-untranslated region (3'-UTR) of its mRNA. Furthermore, the upregulation of VEGF induced by miR‑146a was mediated by Smad4 in the chondrocytes subjected to mechanical pressure injury. These results demonstrated that miR-146a was overexpressed in our chondrocyte model of experimentally induced human mechanical injury, accompanied by the upregulation of VEGF and the downregulation of Smad4 in vitro. Moreover, our data suggest that miR-146a is involved in human chondrocyte apoptosis in response to mechanical injury, and may contribute to the mechanical injury of chondrocytes, as well as to the pathogenesis of OA by increasing the levels of VEGF and damaging the transforming growth factor (TGF)-β signaling pathway through the targeted inhibition of Smad4 in cartilage.
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August-2014
Volume 34 Issue 2

Print ISSN: 1107-3756
Online ISSN:1791-244X

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APA
Jin, L., Zhao, J., Jing, W., Yan, S., Wang, X., Xiao, C., & Ma, B. (2014). Role of miR-146a in human chondrocyte apoptosis in response to mechanical pressure injury in vitro. International Journal of Molecular Medicine, 34, 451-463. https://doi.org/10.3892/ijmm.2014.1808
MLA
Jin, L., Zhao, J., Jing, W., Yan, S., Wang, X., Xiao, C., Ma, B."Role of miR-146a in human chondrocyte apoptosis in response to mechanical pressure injury in vitro". International Journal of Molecular Medicine 34.2 (2014): 451-463.
Chicago
Jin, L., Zhao, J., Jing, W., Yan, S., Wang, X., Xiao, C., Ma, B."Role of miR-146a in human chondrocyte apoptosis in response to mechanical pressure injury in vitro". International Journal of Molecular Medicine 34, no. 2 (2014): 451-463. https://doi.org/10.3892/ijmm.2014.1808