MiR-184 Regulates Proliferation in Nucleus Pulposus Cells by Targeting GAS1

The precise mechanism of nucleus pulposus proliferation in the degeneration of the intervertebral disk pathogenesis remains to be implicated. MicroRNAs (MiRNAs) are a class of 18-22 nucleotides, which are small, noncoding RNAs that inhibit protein translation by binding to the 3'-UTR of target gene. Recent studies have shown that miRNAs play a crucial role in various cell biologies such as cell proliferation, invasion, migration, and cell cycle. However, the role of miR-184 in nucleus pulposus proliferation is still unknown.

qRT-PCR was performed to measure the expression of miR-184. CCK-8 assay, qRT-PCR, and Western blot were used to measure the functional role of miR-184 in nucleus pulposus (NP) cells. Western blot and Luciferase assays were done to find the miR-184 target gene.

We demonstrated that expression of miR-184 was upregulated in degenerative NP tissues compared with that in the control NP tissues, and the expression of miR-184 was positively correlated with disk degeneration grade. We identified Growth Arrest Specific Gene 1 (GAS1) as a direct target gene of miR-184 in NP cells, and ectopic expression of miR-184 promoted NP cells proliferation. In addition, we found that GAS1 expression was downregulated in degenerative NP tissues compared with that in the control NP tissues and the GAS1 expression was inversely correlated with the grade of disk degeneration. Moreover, we demonstrated that miR-184 overexpression could induce AKT phosphorylation and ectopic expression of GAS1 decreased the miR-184 overexpressing NP cells proliferation.

These results demonstrated that miR-184 and the GAS1/Akt pathway may be a potential therapeutic target for intervertebral disc degeneration.