miR-29b inhibits TGF-β1-induced cell proliferation in articular chondrocytes

Transforming growth factor beta 1 (TGF-beta 1) is a known regulator of chondrocyte proliferation and promotes cartilage repair in osteoarthritis (OA). microRNA-29b-3p (miR-29b-3p) is downregulated by TGF-beta 1 and overexpressed in OA cartilage. However, the ability of miR-29b-3p to mediate the chondrocyte pro-proliferative effects of TGF-beta 1 is not yet understood. This current study aimed to investigate the effect of miR-29b-3p on TGF-beta 1-induced cell proliferation in murine articular chondrocytes. The stimulation of chondrocytes by TGF-beta 1 for 24 h resulted in the downregulation of miR-29b-3p expression. The ratio of G0/G1 phase cells decreased in response to TGF-beta 1 whereas the ratio of S phase cells was increased. Consistent with this observation, miR-29b-3p overexpression inhibited TGF-beta 1's ability to promote the ratio of S phase cells and downregulate the ratio of G0/G1 phase cells. These findings suggest that the downregulation of miR-29b-3p is a likely requirement for TGF-beta 1-mediated proliferation of murine articular chondrocytes. Furthermore, implying that miR-29b-3p expression may be involved in reduced chondrocyte proliferation in OA.