Downregulation of miR-27b is Involved in Loss of Type II Collagen by Directly Targeting Matrix Metalloproteinase 13 (MMP13) in Human Intervertebral Disc Degeneration.
Spine (Phila Pa 1976). 2015 Nov 16;
Authors: Li HR, Cui Q, Dong ZY, Zhang JH, Li HQ, Zhao L
STUDY DESIGN: A miRNA study.
OBJECTIVE: The purpose of this study was to identify IDD-specific miRNAs, followed by functional validation of results.
SUMMARY OF BACKGROUND DATA: Intervertebral disc degeneration (IDD) is the major contributor to back radicular pain and the molecular mechanisms underlying this disease are not completely understood. Accumulating evidence suggests that microRNAs (miRNAs) play an important role in IDD, but the role of specific miRNAs involved in this disease remains elusive.
METHODS: An initial screening of nucleus pulposus (NP) tissues miRNA expression by miRNA microarray was performed using samples from 10 patients with degenerative disc disease and 10 patients with lumbar fracture (as controls), respectively. Subsequently, differential expression was validated using qRT-PCR. The level of differentially expressed miRNAs in degenerative NP tissues was investigated. Then, functional analysis of the miRNAs in regulating collagen II expression was carried out. Western blotting and luciferase reporter assay were also used to detect the target gene.
RESULTS: We identified 23 miRNAs that were differentially expressed (16 upregulated and 7 downregulated) in patients compared with controls. Following qRT-PCR confirmation, miR-27b was significantly down-regulated in degenerative NP tissues when compared with controls. Moreover, its level was correlated with grade of disc degeneration. Overexpression of miR- miR-27b promoted type II collagen expression in NP cells. Bioinformatics target prediction identified MMP13 as a putative target of miR-27b. Futhermore, luciferase reporter assays demonstrated that miR-27b directly targets MMP13 and affects the protein expression of MMP13 in NP cells. Expression of MMP13 negatively correlated with miR-27b expression in degenerative NP tissues.
CONCLUSIONS: The downregulation of miR-27b induces type II collagen loss by directly targeting MMP13, leading to the development of IDD. Our study also underscores the potential of miR-27b as a novel therapeutic target in human IDD.
LEVEL OF EVIDENCE: 3.
PMID: 26583473 [PubMed – as supplied by publisher]