Role of miR-589-3p in human lumbar disc degeneration and its potential mechanism

Mechanobiology of MicroRNAs in Intervertebral Disk Degeneration

Intervertebral disk degeneration (IDD) is an intricate pathological process contributing to one of the major causes of low back pain. The degradation of the extracellular matrix (ECM), inflammation, and apoptosis have all been investigated as critical factors involved in the pathology of degenerative disk disease. Additionally, the presence of aberrant microRNAs (miRNAs), conserved molecules that regulate the amount protein post-transcriptionally, may play a crucial role in the pathogenesis of IDD. Research regarding the dysfunction of miRNAs in IDD has been well researched over the past five years. Here, we provide a critical overview of the current knowledge of miRNAs, emphasizing the processes involved in the degenerative disk pathology.

miR-589-3p promoted osteogenic differentiation of periodontal ligament stem cells through targeting ATF1

Background

An increasing number of studies have shown that dysregulated miR-589-3p is associated with multiple diseases. However, the role of miR-589-3p in osteogenic differentiation of periodontal ligament stem cells (PDLSCs) remains unknown. This study aimed to explore the biological function and potential molecular mechanism of miR-589-3p in osteogenic differentiation of PDLSCs.

Methods

GSE159508 was downloaded from Gene Expression Omibus (GEO, http://www.ncbi.nlm.nih.gov/geo/). Differentially expressed miRNAs between osteogenic induction PDLSCs versus non-induction PDLSCs were obtained by R software. miR-589-3p mimic and miR-589-3p inhibitor and corresponding negative control were obtained and to identify the role of miR-589-3p in osteogenic differentiation of PDLSCs. ALP staining and ARS were used to evaluate ALP activity and mineralization, respectively. The targeted binding relationship between miR-589-3p and ATF1 was predicted and verified by target prediction analysis and dual-luciferase assay. Furthermore, the functional mechanism based on miR-589-3p and ATF1 in osteogenic differentiation of PDLSCs was further investigated through rescue experiments.

Results

According to the cut-off criteria with log 2 FC > 1.0 and P < 0.05, 514 differentially expressed miRNAs were identified between osteogenic induction and non-induction PDLSCs, including 309 upregulated miRNAs and 205 downregulated miRNAs. Compared with control PDLSCs, miR-589-3p expression level was notably increased in PDLSCs that underwent osteogenic induction. The overexpression of miR-589-3p promoted the cell viability of PDLSCs, while the low expression of miR-589-3p had the opposite effect. The dual luciferase reporter assay verified that ATF1 was proved to be a direct target of miR-589-3p in PDLSCs. And overexpressed miR-589-3p reduced the expression of ATF1. Overexpression of miR-589-3p enhanced the osteogenic capacity of PDLSCs, as demonstrated by increases in ALP activity, matrix mineralization, and RUNX2, OCN and OSX expression. In addition, the rescue experiments confirmed that overexpressed ATF1 restored the effects of overexpressed miR-589-3p on cell proliferation and osteogenic differentiation of PDLSCs.

Conclusion

miR-589-3p could down-regulate the expression of ATF1, thereby promote the proliferation and osteogenic differentiation of PDLSCs. This finding may provide a new therapeutic target for molecular therapy of periodontitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03000-z.

Role of microRNAs in intervertebral disc degeneration (Review)

The incidence of lower back pain caused by intervertebral disc degeneration (IDD) is gradually increasing. IDD not only affects the quality of life of the patients, but also poses a major socioeconomic burden. There is currently no optimal method for delaying or reversing IDD, mainly due to its unknown pathogenesis. MicroRNAs (miRNAs/miRs) participate in the development of a number of diseases, including IDD. Abnormal expression of miRNAs in the intervertebral disc is implicated in various pathological processes underlying the development of IDD, including nucleus pulposus (NP) cell (NPC) proliferation, NPC apoptosis, extracellular matrix remodeling, inflammation and cartilaginous endplate changes, among others. The focus of the present review was the advances in research on the involvement of miRNAs in the mechanism underlying IDD. Further research is expected to identify markers for early diagnosis of IDD and new targets for delaying or reversing IDD.

TLR4/NF-κB axis signaling pathway-dependent up-regulation of miR-625-5p contributes to human intervertebral disc degeneration by targeting COL1A1

The activation of the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway has been found to play a critical role in many inflammatory diseases by controlling the expression of many cytokines. However, this pathway's role in the pathological process of intervertebral disc degeneration (IDD) has not been reported to date. In the present study, we found universal activation of the TLR4/NF-κB signaling pathway and elevated levels of pro-inflammatory cytokines in IDD patients. The in vitro analyses in human nucleus pulposus cells (hNPC) and annulus fibrosus cells (hAFC) also indicated that Lipopolysaccharide (LPS) treatment could activate TLR4/NF-κB signaling and induce pro-inflammatory cytokine levels. By comparing the results of two microRNA (miRNA)-based microarrays, we identified 15 miRNAs that were dysregulated in both IDD tissues and LPS-treated cells. Of these miRNAs, the most prominently up-regulated was miR-625-5p, which was predicted to bind to the three prime untranslated region (3'-UTR) of collagen type I alpha 1 (COL1A1). In vitro overexpression or down-regulation of miR-625-5p was able to repress or induce the expression of COL1A1, respectively. The in vitro analyses showed that treatment with LPS, recombinant IL-6 or TNF-α could induce miR-625-5p levels but decrease COL1A1 expression. In contrast, the treatments with their corresponding inhibitors, CLI095, siltuximab and D2E7, respectively, resulted in the exact opposite effects. Taken together, our results suggest that activation of the TLR4/NF-κB signaling pathway induces pro-inflammatory cytokines, which further up-regulates the expression of miR-625-5p, resulting in the down-regulation of COL1A1 and eventually contributing to the pathological process of IDD.