Regulation of cell survival by lipid phosphate phosphatases involves the modulation of intracellular phosphatidic acid and sphingosine 1-phosphate pools.
We have shown previously that LPPs (lipid phosphate phosphatases) reduce the stimulation of the p42/p44 MAPK (p42/p44 mitogen-activated protein kinase) pathway by the GPCR (G-protein-coupled receptor) agonists S1P (sphingosine 1-phosphate) and LPA (lysophosphatidic acid) in serum-deprived HEK-293 cells [Alderton, Darroch, Sambi, McKie, Ahmed, N. J. Pyne and S. Pyne (2001) J. Biol. Chem. 276, 13452-13460]. In the present study, we now show that this can be blocked by pretreating HEK-293 cells with the caspase 3/7 inhibitor, Ac-DEVD-CHO [N-acetyl-Asp-Glu-Val-Asp-CHO (aldehyde)]. Therefore LPP2 and LPP3 appear to regulate the apoptotic status of serum-deprived HEK-293 cells. This was supported further by: (i) caspase 3/7-catalysed cleavage of PARP [poly(ADP-ribose) polymerase] was increased in serum-deprived LPP2-overexpressing compared with vector-transfected HEK-293 cells; and (ii) serum-deprived LPP2- and LPP3-overexpressing cells exhibited limited intranucleosomal DNA laddering, which was absent in vector-transfected cells. Moreover, LPP2 reduced basal intracellular phosphatidic acid levels, whereas LPP3 decreased intracellular S1P in serum-deprived HEK-293 cells. LPP2 and LPP3 are constitutively co-localized with SK1 (sphingosine kinase 1) in cytoplasmic vesicles in HEK-293 cells. Moreover, LPP2 but not LPP3 prevents SK1 from being recruited to a perinuclear compartment upon induction of PLD1 (phospholipase D1) in CHO (Chinese-hamster ovary) cells. Taken together, these data are consistent with an important role for LPP2 and LPP3 in regulating an intracellular pool of PA and S1P respectively, that may govern the apoptotic status of the cell upon serum deprivation.
Long
Jaclyn
J
Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, UK.
Darroch
Peter
P
Wan
Kah Fei
KF
Kong
Kok Choi
KC
Ktistakis
Nicholas
N
Pyne
Nigel J
NJ
Pyne
Susan
S
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016466:CHO Cells; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism
D008246:Lysophospholipids; D010712:Phosphatidic Acids; C060506:sphingosine 1-phosphate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C112948:lipid phosphate phosphatase; D010711:Phosphatidate Phosphatase; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases; D013110:Sphingosine; C032881:lysophosphatidic acid