Role of phospholipase D2 in anti‐apoptotic signaling through increased expressions of Bcl‐2 and Bcl‐xL

Abstract

We have previously reported that Fas-resistant A20 cells (FasR) have phospholipase D (PLD) activity upregulated by endogenous PLD2 overexpression. In the present study, we investigated how overexpressed PLD2 in FasR could generate survival signals by regulating the protein levels of anti-apoptotic Bcl-2 and Bcl-xL. To confirm the effect of PLD2 on Bcl-2 protein levels, we transfected PLD2 into wild-type murine B lymphoma A20 cells. The transfected cells showed markedly the increases in Bcl-2 and Bcl-xL protein levels, and became resistant to Fas-induced apoptosis, similar to FasR. Treatment of wild-type A20 cells with phosphatidic acid (PA), the metabolic end product of PLD2 derived from phosphatidylcholin, markedly increased levels of anti-apoptotic Bcl-2 and Bcl-xL proteins. Moreover, PA-induced expressions of Bcl-2 and Bcl-xL were enhanced by propranolol, an inhibitor of PA phospholydrolase (PAP), whereas completely blocked by mepacrine, an inhibitor of phospholipase A(2) (PLA(2)), suggesting that PLA(2) metabolite of PA is responsible for the increases in Bcl-2 and Bcl-xL protein levels. We further confirmed the involvement of arachidonic acid (AA) in PA-induced survival signals by showing that 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA), PA without AA, was unable to increase Bcl-2 and Bcl-xL proteins. Moreover, PA notably increased cyclooxygenase (COX)-2 protein expression, and PA-induced expression of both Bcl-2 and Bcl-xL was inhibited by NS-398, a specific inhibitor of COX-2. Taken together, these findings demonstrate that PA generated by PLD2 plays an important role in cell survival during Fas-mediated apoptosis through the increased Bcl-2 and Bcl-xL protein levels which resulted from PLA(2) and AA-COX2 pathway.

Dipalmitoylphosphatidic acid inhibits breast cancer growth by suppressing angiogenesis via inhibition of the CUX1/FGF1/HGF signalling pathway

“…Recently, the function of DPPA in the regulation of pathological changes has begun to be clarified. Recently reports indicated that DPPA plays a critical role in regulating Bcl‐2 expression in a cell type‐dependent manner 8, 9. In addition, DPPA reportedly inhibits renal interstitial fibrosis in a rat diabetic nephropathy model 10.…”

Molecular Mechanisms of N-Formyl-Methionyl-Leucyl-Phenylalanine-Induced Superoxide Generation and Degranulation in Mouse Neutrophils: Phospholipase D Is Dispensable

“…In contrast, PLD2 has a constitutively high activity in the presence of PI4,5P 2 and is insensitive to PLD1 activators (28,32). PLD2 has been implicated in various cellular events, such as antiapoptosis (38), endocytic recycling (39), endocytosis (40), differentiation of PC12 cells (41), actin-based membrane dynamics (42), and L1-dependent neurite outgrowth (43). Conclusions about some of these PLD functions are based on observations from experiments using primary alcohols, such as ethanol (EtOH) and 1-butanol.…”

Cleavage of phospholipase D1 by caspase promotes apoptosis via modulation of the p53-dependent cell death pathway

“…In response to Fas, PLD has been reported to prevent apoptosis by generating PA and increasing Bcl-2 and Bcl-xL expression. 31 In response to the mitochondrial apoptotic signal, PLD is known to prevent apoptosis due to the elevation of PA levels and the subsequent decrease in the expression of tumor suppressor genes such as Egr-1 and PTEN.…”