Phospholipase D1 as a key enzyme for decidualization in human endometrial stromal cells

Abstract

We investigated the role of Phospholipase D1 (PLD1) in 8-Br-cAMP-induced decidualization in human endometrial stromal cells (ES cells), which is morphological and biological differentiation process. In ES cells, PLD activity was increased by the treatment with 0.5 mM 8-Br-cAMP, maximally at 5 min. Using pharmacological inhibitor and dominant negative form of Src, our present study suggested that PKA/Src/ERK may represent an upstream pathway for PLD in 8-Br-cAMP-induced signalling of ES cells. Moreover, prolonged exposure to 8-Br-cAMP increased the activity and expression level of PLD1 and decidualized cells, while no discernible change was observed in the untreated cells. We confirmed the changes of PLD1 with decidualization of ES cells by transfecting ES cells with dominant negative rPLD1, hPLD1 and hPLD2, respectively. We also found that ERK was activated time dependently, when we treated the cells with 8-Br-cAMP for 12 days. On the other hand, PLD activity and ERK activation were decreased by cotreatment of the cells with PP2 (Src inhibitor, 10uM/ml) and 8-Br-cAMP or PD98059 (MEK inhibitor, 50uM/ml) and 8-Br-cAMP, leading to suppress decidualization. However, these inhibitors did not change the expression level of PLD1, suggesting that the expression level and the activation pathway of PLD1 were essential for decidualization of ES cells. Taken together, we propose that upregulation of PLD may regulate cellular function coupled with decidualization in ES cells.