Inhibited microRNA-494-5p promotes proliferation and suppresses senescence of nucleus pulposus cells in mice with intervertebral disc degeneration by elevating TIMP3

It has been unraveled that microRNAs (miRNAs) played crucial roles in processes of human diseases, while the role of miR-494-5p in intervertebral disc degeneration (IDD) remains scarcely studied. We aimed to investigate the mechanisms of miR-494-5p in IDD with the involvement of tissue inhibitor of metalloproteinase 3 (TIMP3). Expression of miR-494-5p and TIMP3 in IDD clinical specimens was assessed. The IDD models were established by needle punching, which were then injected with low expression of miR-494-5p or TIMP3 overexpression lentivirus to observe their effects on pathology and apoptosis in IDD mice. The nucleus pulposus cells were isolated and, respectively, treated with miR-494-5p inhibitor or TIMP3 overexpression plasmid to determine the viability, apoptosis, and senescence in vitro. Furthermore, the expression of Aggrecan, Col-2, Caveolin-1, and SA-β-gal in nucleus pulposus cells in vitro were measured. The target relation between miR-494-5p and TIMP3 was determined. An increased expression of miR-494-5p and a decreased expression of TIMP3 were found in IDD. Downregulation of miR-494-5p or overexpression of TIMP3 could relieve pathology and suppress nucleus pulposus cell apoptosis in IDD mice, as well as promote the viability and attenuate the apoptosis and senescence of nucleus pulposus cells from IDD mice. Moreover, inhibition of miR-494-5p or overexpression of TIMP3 upregulated Aggrecan and Col-2 expression while downregulated Caveolin-1 and SA-β-gal expression, and TIMP3 was the target gene of miR-494-5p. Results of this study indicated that the degradation of miR-494-5p ameliorates the development of IDD by elevating TIPM3, which may provide new targets for IDD treatment.