Arachidonoyl-phosphatidylcholine oscillates during the cell cycle and counteracts proliferation by suppressing Akt membrane binding.
The activity of protein kinase B (Akt)--a major kinase promoting cell proliferation and survival--oscillates during the cell cycle. To investigate whether membrane phospholipids may regulate Akt phosphorylation and thus activity, we monitored the lipid profile of nocodazole-synchronized mouse NIH 3T3 fibroblasts during the cell cycle by liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS). The proportion of sn-2-arachidonoyl-phosphatidylcholine (20:4-PC) inversely correlated with Akt activity. Increasing the cellular ratio of 20:4-PC by supplementation of 20:4-PC to the cell culture medium diminished Akt [serine (Ser)473] phosphorylation. Saturated and monounsaturated phosphatidylcholines, used as control had no effect; 20:4-PC reduced cell proliferation relative to controls, interfered with S-phase transition, and suppressed Akt downstream signaling and cyclin expression like LY294002, which is a specific inhibitor of the phosphatidylinositol-3-kinase/Akt pathway. Additive effects of 20:4-PC and LY294002 were not observed, underlining the critical role of Akt for 20:4-PC signaling; 20:4-PC suppressed Akt membrane translocation as shown by immunofluorescence microscopy but left the concentration of the anchor lipid phosphatidylinositol-3,4,5-trisphosphate unchanged. An in vitro binding assay suggests that 20:4-PC attenuates the interaction of Akt with its membrane binding site. We conclude that 20:4-PC oscillates during the cell cycle and delays cell cycle progression by inhibiting Akt membrane binding.
Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University, 07743 Jena, Germany. andreas.koeberle@uni-jena.de
Andreas
A
Koeberle
Hideo
H
Shindou
Solveigh C
SC
Koeberle
Stefan A
SA
Laufer
Takao
T
Shimizu
Oliver
O
Werz
D000818:Animals; D002453:Cell Cycle / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects*; D002853:Chromatography, Liquid; D002867:Chromones / Q000378:metabolism / Q000494:pharmacology; D008244:Lysophosphatidylcholines / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D008856:Microscopy, Fluorescence; D009025:Morpholines / Q000378:metabolism / Q000494:pharmacology; D041681:NIH 3T3 Cells; D015739:Nocodazole; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
C503491:2-arachidonoyllysophosphatidylcholine; D002867:Chromones; D008244:Lysophosphatidylcholines; D009025:Morpholines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D051057:Proto-Oncogene Proteins c-akt; D015739:Nocodazole