Expression and regulatory role of miRNA-222 in intervertebral disc degeneration (IDD)

Abstract

The aim of this study was to investigate the expression of miRNA-222 in intervertebral disc degeneration (IDD), and explore its regulatory mechanism. Totally 30 patients with IDD and 36 normal control subjects were included. Quantitative real-time polymerase chain reaction (PCR), Western blot analysis, and enzyme-linked immunosorbent assay (ELISA) were preformed to detect the mRNA and protein expression levels of MMP1, and the miRNA-222 expression levels, in the nucleus pulposus (NP) tissues and blood samples. Bioinformatics analysis was performed, and dual-luciferase reporter assay was conducted for confirmation. HNPC cells were cultured in vitro, and the effects of agomiRNA-222 transfection were analyzed. The results showed that MMP1 expression was significantly up-regulated in the NP tissues and blood samples of patients with IDD, and the miRNA-222 expression was significantly down-regulated in both specimens. Bioinformatics analysis showed that MMP1 was the direct target for miRNA-222, which was confirmed by the dual-luciferase reporter assay. Over-expression of miRNA-222 significantly decreased the expression levels of MMP1 in HNPC cells in vitro, and the expression levels of type II collagen were significantly up-regulated. These results suggest that MMP1 expression is up-regulated in the NP and blood of patients with IDD, which may be related to the down-regulation of miRNA-222. The miRNA-222 may regulate the expression of related proteins in intervertebral disc nucleus cells through MMP1, thus affecting the disease pathogenesis and development.

Keywords:

• Intervertebral disc degeneration (IDD)
• nucleus pulposus
• miRNA-222
• MMP1
• type II collagen

Acknowledgement

We thank Director Peng Cao, Department of Orthopaedics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, for the kind assistance.

Disclosure statement

All authors declare no financial competing interests and no non-financial competing interests.