マイクロRNA-544a-3p：関節軟骨および変形性関節症におけるWntシグナル伝達ネットワークの新たな調節因子

Determining the effect of microRNA-544a-3p (miR-544a-3p) in articular chondrocytes isolated from patients affected by osteoarthritis (OA) and its role in the modulation of the Wnt signalling.

Articular chondrocytes were isolated from patients undergoing joint replacement because of OA. Expression levels of miR-544a-3p were measured by PCR and in situ hybridization. Putative targets of miR-544a-3p were confirmed by reporter assay and qPCR in cells stimulated with a miR-544a-3p mimic. The effect of miR-544a-3p on chondrocyte metabolism was monitored by qPCR for phenotypic markers, protein expression levels of aggrecan neoepitopes/MMP-13 and modulation of proteoglycan content in micromass cultures, upon stimulation with a miR-544a-3p mimic. The expression levels of MMP-13 and Aggrecan neoepitopes in response to miR-544a-3p stimulation was also measured in co-stimulation with XAV-939 and KN93, respectively β-catenin and CaMKII inhibitors.

Our results suggest that miR-544a-3p enhances the activation of the Wnt-signalling in articular chondrocytes. The expression of miR-544a-3p is higher in chondrocytes isolated from damaged (median difference Hodges-Lehman, damaged vs preserved, 1.480, 95%CI, 0.1794 to 2.784, p=0.0097) areas of the articular cartilage removed from OA patients, and can be upregulated by pro-inflammatory cytokines. miR-544a-3p exerts a pro-catabolic effect on articular chondrocytes, which is rescued both by the inhibition of the Wnt/β-catenin and Wnt/CaMKII signalling pathways.

Our results point to miR-544a-3p as a new, important modulator of the Wnt signalling network within the articular cartilage suggesting a key role for microRNAs in regulating how the multiple branches of the network and their interaction modulate cartilage homeostasis.