Role of phospholipase D2 in anti-apoptotic signaling through increased expressions of Bcl-2 and Bcl-xL.
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.
Oh
Kyoung-Jin
KJ
Institute of Biomedical Science and Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul 133-791, Korea.
Lee
Sung-Chang
SC
Choi
Hye-Jin
HJ
Oh
Doo-Yi
DY
Kim
Sang-Chul
SC
Min
Do Sik
do S
Kim
Jung Mogg
JM
Lee
Ki Sung
KS
Han
Joong-Soo
JS
D000818:Animals; D000959:Antihypertensive Agents / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D051379:Mice; D010168:Palmitates / Q000378:metabolism; D010712:Phosphatidic Acids / Q000378:metabolism; D010739:Phospholipase D / Q000235:genetics / Q000378:metabolism*; D011433:Propranolol / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D011796:Quinacrine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism
D000959:Antihypertensive Agents; C494812:Bcl2l1 protein, mouse; D004791:Enzyme Inhibitors; D010168:Palmitates; D010712:Phosphatidic Acids; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D019014:fas Receptor; C031599:dipalmitoylphosphatidic acid; D011433:Propranolol; D051546:Cyclooxygenase 2; C105606:phospholipase D2; D010739:Phospholipase D; D011796:Quinacrine