Overexpression of miR-148a-3p inhibits extracellular matrix degradation and alleviates IL-1β-induced intervertebral disc degeneration

Objective(s): Recently, studies on microRNAs (miRNAs) and their targets and related genes have provided new therapeutic opportunities for controlling intervertebral disc degeneration (IDD). We aimed to investigate the effects of miR-148a-3p overexpression on IDD progression.Materials and Methods: This study used microRNA microarrays to analyze key regulators of IDD. Q-PCR was used to verify the IL-1 beta-induced down-regulation of miR-148a-3p expression both in nucleus pulposus (NP) tissues of IDD patients and in degenerated NP cells (NPCs) of rats. Rat NPC micromass cultures and ex vivo intervertebral disc (IVD) culture models were established, and histological staining was performed to verify the effect of miR-148a-3p on the general morphology and proteoglycan and collagen contents of IVDs. In addition, q-PCR and western blotting analyses were performed to examine the expression of ECM molecules and matrix-degrading enzymes. A luciferase reporter assay was used to confirm the target genes of miR-148a-3p.Results: Our data revealed that miR-148a-3p was down-regulated in IDD. Overexpression of miR-148a-3p had no effect on ACAN or COL2A1 gene expression but decreased MMP3, MMP13, and ADAMTS5 gene expression. The matrix deposited by miR-148a-3p-overexpressing rat NPCs contained high levels of proteoglycans and collagen. The ex vivo experiments verified that agomiR-148a-3p alleviated the NPC matrix degradation induced by IL-1 beta. A luciferase reporter assay confirmed that miR-148a-3p directly targeted ADAMTS5 and MMP13.Conclusion: We proved that miR-148a-3p can attenuate ECM loss and protect NP function by inhibiting matrix-degrading enzymes.