Up-regulation of estrogen receptor-beta expression during osteogenic differentiation of human periodontal ligament cells.

BACKGROUND AND OBJECTIVE

Estrogen has been shown to up-regulate the expression of osteoblastic phenotypes of human periodontal ligament cells via binding to estrogen receptors and may also help periodontal tissue regeneration. However, which subtype of estrogen receptor (alpha or beta) is predominately expressed in human periodontal ligament cells, and how estrogen receptor expression is regulated during the osteogenic differentiation of human periodontal ligament cells, is still unclear. This study aimed to explore the expression and regulation of estrogen receptor subtypes in human periodontal ligament cells and during their osteogenic differentiation.

MATERIAL AND METHODS

Human periodontal ligament cells derived from 10 individual age-matched donors (five male and five female donors) were cultured. Human periodontal ligament cells under osteogenic induction (group M) and the corresponding controls (group C) were harvested on days 7, 14 and 21 for estrogen receptor detection.

RESULTS

Both estrogen receptor-alpha and estrogen receptor-beta mRNAs were expressed in human periodontal ligament cells from all of the 10 donors. Protein only of estrogen receptor-beta (not of estrogen receptor-alpha) was detected and was shown to be located in the nuclei of human periodontal ligament cells. The expression levels of estrogen receptor-beta mRNA and protein from both male and female donors in group M were significantly higher compared with group C during the 21-d study period. In comparison, the expression level of estrogen receptor-alpha mRNA of the donors was not significantly different from that of the controls during osteogenic differentiation and no estrogen receptor-alpha protein was detected.

CONCLUSION

The results suggest that estrogen receptor-beta may be the predominant subtype expressed in human periodontal ligament cells and may actively participate in the osteogenic differentiation process of human periodontal ligament cells, both in male and in female subjects.