Overexpression of phospholipase D1 enhances Bcl-2 expression through STAT3 in HeLa cells

Abstract

Phospholipase D (PLD) catalyzes the hydrolysis of phosphatidylcholine to generate phosphatidic acid (PA) and choline. PLD isozymes are implicated a diverse range of cellular processes, including receptor signaling, membrane transport control, and actin cytoskeleton reorganization. However, the molecular mechanisms how PLD1 enhances Bcl-2 expression are unknown. In this study, we demonstrate that the increased expression of PLD1 is important for inducing the Bcl-2 expression. Overexpression of PLD1 increased Bcl-2 expression and dominant negative PLD1 decreased Bcl-2 expression. PA, the production of PLDs, also resulted in upregulation of Bcl-2 expression. Treatment of PA activated the RhoA-ROCK/p38 MAPK and PLA2/ERK MAPK pathway. PA-induced Bcl-2 expression was attenuated by dominant negative RhoA, a specific Pho-kinase inhibitor (Y-27632), PLA2 inhibitor (mepacrine), p38MAPK inhibitor (SB202190) and ERK MAPK inhibitor (PD98059). These results indicate that Bcl-2 expression is related to the RhoA-ROCK/p38 MAPK and PLA2/ERK MAPK pathway. From these results, we tried to find out transcription factor controlled by PLD using siRNA transfection. When STAT3 activity was blocked by STAT3 siRNA, PA-induced Bcl-2 expression is remarkably decreased. Suggesting that STAT3 (ser727) is essential transcription factor linking PLD to Bcl-2 upregulation. Taken together, these findings indicate that PLD acts as an important regulator in Bcl-2 expression by activation of STAT3 (ser727) through RhoA-ROCK/p38 MAPK and PLA2/ERK MAPK pathway