Epigenetic modification of miR-217 promotes intervertebral disc degeneration by targeting the FBXO21-ERK signalling pathway

Numerous potential therapeutic alternatives for intervertebral disc degeneration (IDD) have been investigated, the most promising of which are based on biological variables such as microRNAs (miRNAs). Therefore, we verified the hypothesis that miRNAs modulate IDD by affecting the FBXO21-ERK signalling pathway.Microarray and quantitative real-time polymerase chain reaction (RT-qPCR) tests were used to examine the expression profiles of miRNAs in nucleus pulposus (NP) cells between patients with IDD and controls. Western blotting and luciferase reporter assays were used to identify the miRNA targets.Microarray and RT-qPCR assays confirmed that the expression level of miR-217 was significantly decreased in degenerative NP cells. CpG islands were predicted in the miR-217 promoter region. The IDD group had considerably higher methylation than the control group. Gain- and loss-of-function experiments revealed that miR-217 mimics inhibited apoptosis and extracellular matrix (ECM) breakdown in NP cells. Bioinformatic analyses and luciferase assays were used to determine the connection between miR-217 and FBXO21. In vitro tests revealed that miR-217 mimics inhibited the expression of FBXO21, pERK, MMP13, and ADAMTS5 proteins, successfully protecting the ECM from degradation. Additionally, in vivo investigation using the IDD mouse model demonstrated that the miR-217 agonist may sufficiently promote NP cell proliferation, decrease apoptosis, promote ECM synthesis, and suppress the expression of matrix-degrading enzymes in NP cells.Overexpression of miR-217 inhibits IDD via FBXO21/ERK regulation.This study was performed in strict accordance with the NIH guidelines for the care and use of laboratory animals (NIH Publication No. 85-23 Rev. 1985) and was approved by the human research ethics committee of Wuhan University Renmin Hospital (Approval No. RMHREC-D-2020-391), and written informed consent was obtained from each participant.