RESUMO
OBJECTIVE: Due to the decrease of estrogen and estrogen receptor (ER) in postmenopausal women, they have a higher risk of intervertebral disc degeneration (IDD) than men. This study aims to explore how ERα and ERb interact with CCN5 and protect IDD. PATIENTS AND METHODS: We used Chromatin immunoprecipitation (ChIP) and Luciferase reporter assay to determine whether the ERα/b protein binds to CCN5 promoter and activates its expression. We used TNF-α to induce nucleus pulposus (NP) cell degeneration to simulate the IDD process. The change of the expression of ERα/ß and CCN5 was measured in the degenerated NP cells. To understand the function of ERα/ß in the NP cells degeneration, we upregulated the ERα/b gene expression by vector transfection or 17b-estradiol (E2) stimulation. Besides, we also used the CCN5 gene-silenced NP cells by siRNA transfection as a comparison to determine the role of CCN5. We tested the cell proliferation and principal components of the extracellular matrix (ECM) to value the degree of NP cell degeneration. RESULTS: ERα and ERß protein can bind to the same promoter regions of CCN5 and activate its expression, respectively. TNF-α degraded NP cells with a reduction of cell proliferation, collagen II, ACAN, ERα, ERß, and CCN5 expression, and increased collagen I/III, and MMP-13 expression. Upregulated ERα or ERß resulted in the maintains of CCN5 and alleviated the NP cell degeneration. Besides, 17ß-E2 supplement increased the ERα, ERß, and CCN5 expression, as well as stable NP cells phenotype. However, it was partly abolished by the silencing of CCN5. CONCLUSIONS: Upregulation of ERα and ERß protects the NP cell degeneration during IDD through the activation of CCN5 by binding to its promoter.
