Objective: A previous study reported that glucose-regulated protein 94 (GRP94) is involved in mechanical stress-induced chondrocyte apoptosis; however, the underlying molecular mechanisms remain unknown. The present study aimed to investigate the post-transcriptional regulatory mechanism of microRNAs (miRs) in mechanical stress-induced chondrocyte apoptosis by targeting GRP94.
Materials and methods: Annexin V-fluorescein isothiocyanate/propidium iodide (PI) staining was conducted to evaluate the apoptosis of chondrocytes. The mRNA and protein expression levels were measured by reverse transcription-quantitative polymerase chain reaction and Western blotting, respectively. The targeted genes were predicted using a bioinformatics tool and further investigated via a luciferase reporter assay.
Results: The results demonstrated that cyclic loading led to significant increases in GRP94 expression in chondrocytes; however, the expression levels of miR-150 were downregulated. Bioinformatics analysis and a luciferase reporter assay indicated that GRP94 was a direct target of miR-150, as the expression of GRP94 was dysregulated following transfection with miR-150 mimics or inhibitors. In addition, mechanical stress-induced chondrocyte apoptosis was suppressed by transfection with miR-150 mimics, while the protective effects of miR-150 mimics in this process were inhibited by GRP94 overexpression.
Conclusions: MiR-150 upregulation suppressed mechanical stress-induced chondrocyte apoptosis; the underlying molecular mechanism may be mediated, at least partially, via the inhibition of GRP94 expression.