Long intergenic non-protein coding RNA 00707 regulates chondrocyte apoptosis and proliferation in osteoarthritis by serving as a sponge for microRNA-199-3p

Abstract

It is known that long intergenic non-protein coding RNA 00707 (LINC00707) promotes lipopolysaccharide (LPS)-injury and microRNA-199-3p (miR-199-3p) regulates chondrocyte proliferation and apoptosis. Both processes participate in osteoarthritis (OA). We predicted that LINC00707 and miR-199-3p may interact with each other. Therefore, LINC00707 and miR-199-3p may interact with each other to participate in OA. In this study, the expression of LINC00707 and miR-199-3p in both OA and normal articular cartilage tissues was analyzed using RT-qPCR. The subcellular location of LINC00707 and its direct interaction with miR-199-3p were explored by nuclear fractionation assay, RNA pull-down assay and Luciferase reporter assay, respectively. The role of LINC00707 and miR-199-3p in regulating the expression of each other was analyzed using an overexpression assay, followed by RT-qPCR. The role of LINC00707 and miR-199-3p in regulating OA chondrocyte proliferation and apoptosis was analyzed by BrdU assay and cell apoptosis assay, respectively. OA tissues exhibited increased expression of LINC00707 and decreased expression of miR-199-3p. LINC00707 directly interacted with miR-199-3p in cytoplasm. However, LINC00707 and miR-199-3p overexpression failed to affect each other's expression. LPS treatment increased LINC00707 expression and decreased miR-199-3p expression in OA chondrocyte. LINC00707 overexpression increased the apoptosis of OA chondrocytes induced by LPS and suppressed the proliferation of OA chondrocytes. Moreover, LINC00707 suppressed the role of miR-199-3p in enhancing cell proliferation and suppressing cell apoptosis. In conclusion, LINC00707 can be detected in cytoplasm and it may sponge miR-199-3p to regulate chondrocyte proliferation and apoptosis in OA.

Keywords: LINC00707; apoptosis; miR-199-3p; osteoarthritis; proliferation.

Graphical abstract

Figure 1.

RT-qPCR analysis of the expression of LINC00707 and miR-199-3p in OA.

Figure 2.

Subcellular location of LINC00707 in chondrocytes and analysis of its interaction with miR-199-3p. To analyze the subcellular location of LINC00707, nuclear fractionation assay was performed on chondrocytes (a). The interaction between LINC00707 and miR-199-3p was predicted by IntaRNA 2.0 (b). The direct interaction between LINC00707 and miR-199-3p was analyzed by RNA pull-down assay (c). Dual-luciferase reporter assay was performed by transfecting LINC00707 and miRNA NC or LINC00707 and miR-199-3p into chondrocytes (d). *p < 0.05; ***p < 0.001.

Figure 3.

Analysis of the regulator roles of LINC00707 and miR-199-3p in the expression of each other. The direct interaction may indicate the regulator roles of LINC00707 and miR-199-3p in the expression of each other. Pearson’s correlation coefficient analysis was done to analyze the correlations between LINC00707 and miR-199-3p across OA (a) and control (b) samples. Chondrocytes were overexpressed with LINC00707 or miR-199-3p, and the overexpression was confirmed by RT-qPCR every 24 h until 72 h (c). The role of LINC00707 in the expression of miR-199-3p (d), and the role of miR-199-3p in the expression of LINC00707 (e) were analyzed by RT-qPCR. *p < 0.05.

Figure 4.

Analysis of the roles of LINC00707 and miR-199-3p in the proliferation and apoptosis of chondrocytes. The roles of LINC00707 and miR-199-3p in the proliferation and apoptosis (induced by 10 μg/ml LPS for 24 h) of chondrocytes were analyzed by BrdU assay (a) and cell apoptosis assay (b), respectively. *p < 0.05.