Abstract: Objective To observe the effect of interleukin-1β (IL-1β) on expression of Matrix Metalloproteinases 13 (MMP-13) in rat chondrocytes and its regulation of miR-27b. Methods Chondrocytes were extracted from 7 Wistar male rats. Expression of MMP-13 were examined by Western blot at 0 h, 24 h, 48 h after IL-1β stimulation. Differential miRNAs expression profiles were examined by miRNAs microarray. The most obviously down-regulated miRNAs were confirmed by quantitative Real-time PCR. Targeted regulation relationship between miR-27b and MMP-13 was set up by Luciferase re⁃ porter gene experiments. Results Expression of MMP-13 in rat chondrocytes was increased at a timely dependent manner upon IL-1β stimulation(P < 0.05)；Microarray revealed 36 miRNAs whose expression changed, among which 6（miR-27b, miR-31, miR-26a, miR-26b, miR-23, miR-204）were especially obvious. Real-time PCR confirmed that miR-27b was the one whose expression level were most down-regulated. Transient co-transfection of miR-27b mimics with luciferase expres⁃ sion plasmids resulted in significant repression of luciferase activity in rat chondrocytes (P < 0.05). Conclusion IL-1β stimulation result in down-regulation of miR-27b and up-regulation of MMP-13 expression. MiR-27b and MMP-13 show targeted regulation relationship.

Key words: chondrocytes, matrix metalloproteinase 13, microRNAs, interleukin-1beta, microarray analysis, miR-27b