The role of microRNA-3085 in chondrocyte function

Sci Rep. 2020 Dec 14;10(1):21923. doi: 10.1038/s41598-020-78606-6.

Abstract

MicroRNAs have been shown to play a role in cartilage development, homeostasis and breakdown during osteoarthritis. We previously identified miR-3085 in humans as a chondrocyte-selective microRNA, however it could not be detected by Northern blot. The aim of the current study was to prove that miR-3085 is a microRNA and to investigate the function of miR-3085 in signaling pathways relevant to cartilage homeostasis and osteoarthritis. Here, we confirm that miR-3085 is a microRNA and not another class of small RNA using (1) a pre-miR hairpin maturation assay, (2) expression levels in a Dicer null cell line, and (3) Ago2 pulldown. MicroRNA-3085-3p is expressed more highly in micromass than monolayer cultured chondrocytes. Transfection of miR-3085-3p into chondrocytes decreases expression of COL2A1 and ACAN, both of which are validated as direct targets of miR-3085-3p. Interleukin-1 induces the expression of miR-3085-3p, at least in part via NFκB. In a feed-forward mechanism, miR-3085-3p then potentiates NFκB signaling. However, at early time points after transfection, its action appears to be inhibitory. MyD88 has been shown to be a direct target of miR-3085-3p and may be responsible for the early inhibition of NFκB signaling. However, at later time points, MyD88 knockdown remains inhibitory and so other functions of miR-3085-3p are clearly dominant. TGFβ1 also induces the expression of miR-3085-3p, but in this instance, it exerts a feedback inhibition on signaling with SMAD3 and SMAD4 shown to be direct targets. This in vitro analysis shows that miR-3085-3p functions in chondrocytes to induce IL-1-signaling, reduce TGFβ1 signaling, and inhibit expression of matrix genes. These data suggest that miR-3085-3p has a role in chondrocyte function and could contribute to the process of osteoarthritis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aggrecans / biosynthesis
  • Aggrecans / genetics
  • Cell Line, Tumor
  • Chondrocytes / metabolism*
  • Collagen Type II / biosynthesis
  • Collagen Type II / genetics
  • Gene Expression Regulation*
  • Humans
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / metabolism
  • Signal Transduction*

Substances

  • ACAN protein, human
  • Aggrecans
  • COL2A1 protein, human
  • Collagen Type II
  • MIRN-3085 microRNA, human
  • MYD88 protein, human
  • MicroRNAs
  • Myeloid Differentiation Factor 88