LH upregulates connexin 43 expression in granulosa cells by activating the Wnt/ß-catenin signalling pathway.

Connexin (Cx) 43 is the most widely expressed gap junction protein in follicle granulosa cells and plays an important role in follicle development and growth. The aims of this study were to investigate the effects of LH on the expression of Cx43 and key proteins in the downstream Wnt-ß/catenin signalling pathway and to explore the mechanism underlying the regulation of Cx43 expression in granulosa cells. Primary culture granulosa cells were obtained from 21-day-old Sprague-Dawley rats, and were treated with different concentrations of LH (150, 300 and 600 IU L-1). Cx43 expression in granulosa cells was detected using immunofluorescence. Western blotting was used to detect the expression of Cx43, ß-catenin and Axin2 proteins (Axin2 is a protein that in humans is encoded by the AXIN2 gene, which presumably plays an important role in the regulation of the stability of ß-catenin in the Wnt signaling pathway) in granulosa cells with and without FH535 treatment (a Wnt/ß-catenin signalling pathway inhibitor). Cx43 expression was detected in the cytoplasm and cell membrane of granulosa cells. Treatment with a high concentration of LH (300 IU L-1) increased the expression of ß-catenin and Axin2, as well as that of Cx43. FH535 treatment reduced the LH-induced increases in Cx43, ß-catenin and Axin2. These results indicate that LH upregulates Cx43 expression in granular cells by activating the Wnt/ß-catenin signalling pathway.