House dust mite allergen Der f 2-induced phospholipase D1 activation is critical for the production of interleukin-13 through activating transcription factor-2 activation in human bronchial epithelial cells

Abstract

The purpose of this study was to identify the role of phospholipase D1 (PLD1) inDer f2-induced interleukin (IL)-13 production. The major house dust mite allergen, Der f2, increased PLD activity in human bronchial epithelial cells (BEAS-2B), and dominant negative PLD1 or PLD1 siRNA decreased Der f2-induced IL-13 expression and production. Treatment of Der f2 activated the phospholipase Cγ (PLCγ)/protein kinase Cα (PKCα)/p38 MAPK pathway. Der f2-induced PLD activation was attenuated by PLCγ inhibitors (U73122 and PAO), PKCα inhibitors (RO320432 and GO6976), and p38 MAPK inhibitors (SB203580 and SB202190). These results indicate that PLCγ, PKCα, and p38 MAPK act as upstream activators of PLD in Der f2-treated BEAS-2B cells. Furthermore, expression and production of IL-13 increased by Der f2 were also blocked by inhibition of PLCγ, PKCα, or p38 MAPK, indicating that IL-13 expression and production are related to a PLCγ/PKCα/p38 MAPK pathway. We found that activating transcription factor-2 (ATF-2) was activated by Der f2 in BEAS-2B cells and activation of ATF-2 was controlled by PLD1. When ATF-2 activity was blocked with ATF-2 siRNA, Der f2-induced IL-13 expression and production were decreased. Thus, ATF-2 might be one of the transcriptional factors for the expression of IL-13 in Der f2-treated BEAS-2B cells. Taken together, PLD1 acts as an important regulator in Der f2-induced expression and production of IL-13 through activation of ATF-2 in BEAS-2B cells. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.