Early changes in inositol lipids and their metabolites induced by platelet-derived growth factor in quiescent Swiss mouse 3T3 cells

Inositol lipid turnover was studied in quiescent Swiss mouse 3T3 cells stimulated by platelet-derived growth factor (PDGF). Stimulation of the cells by PDGF for 10 min at 37 degrees C induced the following changes in lipids: in cells prelabelled with [32P]Pi, a 28% decrease in [32P]phosphatidylinositol 4,5-bisphosphate, a 41% decrease in [32P]phosphatidylinositol 4-phosphate and a 1.7-fold increase in the 32P-labelling of phosphatidic acid; in cells prelabelled with [3H8]arachidonic acid, a 17.9-fold increase in [3H]phosphatidic acid, a 20% decrease in [3H]phosphatidylinositol (PtdIns), an 8.6-fold increase in [3H]arachidonic acid released into the medium, a 57-fold increase in [3H]prostaglandin E2 in the medium, and a 5.3-fold increase in [3H]monoacylglycerol released into the medium (the last was identified as the 2-acyl derivative); in cells prelabelled with [2-3H]glycerol, a 1.7-fold increase in [3H]diacylglycerol, a 6.7-fold increase in [3H]phosphatidic acid, a 1.6-fold increase in [3H]lysophosphatidylcholine (lysoPtdCho), a 9% decrease in [3H]PtdIns, and a 1.6-fold increase in [3H]monoacylglycerol released into the medium. PDGF stimulated the formation of inositol tris-, bis- and mono-phosphates in the cells prelabelled with myo-[2-3H]inositol. These results indicate that, in Swiss 3T3 cells stimulated by PDGF, diacylglycerol produced by the hydrolysis of inositol lipids is partly degraded to 2-acylglycerol and partly converted into phosphatidic acid. The increase in lysoPtdCho indicates that a portion of arachidonic acid released from the stimulated cells is formed by the hydrolysis of PtdCho with a phospholipase A2. Different values of half-maximal doses of the partially purified PDGF used in this study were found for the various responses of quiescent Swiss 3T3 cells to PDGF. The values for half-maximal doses suggest that activation of a fraction of the cell-surface receptor for PDGF is sufficient for mitogenesis and for an increase in the cytoplasmic free Ca2+ concentration, and that the PGDF-stimulated lipid metabolism is probably proportional to the number of receptor sites activated by PDGF.

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The LDL receptor pathway delivers arachidonic acid for eicosanoid formation in cells stimulated by platelet-derived growth factor

Nature ◽

10.1038/345634a0 ◽

1990 ◽

Vol 345 (6276) ◽

pp. 634-636 ◽

Cited By ~ 70

Author(s):

Andreas J. R. Habenicht ◽

Peter Salbach ◽

Matthias Goerig ◽

Wolfgang Zeh ◽

Uwe Janssen-Timmen ◽

...

Keyword(s):

Arachidonic Acid ◽

Growth Factor ◽

Ldl Receptor ◽

Platelet Derived Growth Factor ◽

Eicosanoid Formation ◽

In Cells

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Platelet-derived growth factor induces rapid and sustained tyrosine phosphorylation of phospholipase C-gamma in quiescent BALB/c 3T3 cells

Molecular and Cellular Biology ◽

10.1128/mcb.9.7.2934-2943.1989 ◽

1989 ◽

Vol 9 (7) ◽

pp. 2934-2943

Author(s):

M I Wahl ◽

N E Olashaw ◽

S Nishibe ◽

S G Rhee ◽

W J Pledger ◽

...

Keyword(s):

Growth Factor ◽

Phospholipase C ◽

Tyrosine Phosphorylation ◽

Tyrosine Kinases ◽

Hormonal Regulation ◽

Growth Factor Receptor ◽

Fold Increase ◽

Platelet Derived Growth Factor ◽

3T3 Cells ◽

Pdgf Stimulation

Platelet-derived growth factor (PDGF) stimulates the proliferation of quiescent fibroblasts through a series of events initiated by activation of tyrosine kinase activity of the PDGF receptor at the cell surface. Physiologically significant substrates for this or other growth factor receptor or oncogene tyrosine kinases have been difficult to identify. Phospholipase C (PLC), a key enzyme of the phosphoinositide pathway, is believed to be an important site for hormonal regulation of the hydrolysis of phosphatidylinositol 4,5-bisphosphate, which produces the intracellular second-messenger molecules inositol 1,4,5-trisphosphate and 1,2-diacylglycerol. Treatment of BALB/c 3T3 cells with PDGF led to a rapid (within 1 min) and significant (greater than 50-fold) increase in PLC activity, as detected in eluates of proteins from a phosphotyrosine immunoaffinity matrix. This PDGF-stimulated increase in phosphotyrosine-immunopurified PLC activity occurred for up to 12 h after addition of growth factor to quiescent cells. Interestingly, the PDGF stimulation occurred at 3 as well as 37 degrees C and in the absence or presence of extracellular Ca2+. Immunoprecipitation of cellular proteins with monoclonal antibodies specific for three distinct cytosolic PLC isozymes demonstrated the presence of a 145-kilodalton isozyme, PLC-gamma (formerly PLC-II), in BALB/c 3T3 cells. Furthermore, these immunoprecipitation studies showed that PLC-gamma is rapidly phosphorylated on tyrosine residues after PDGF stimulation. The results suggest that mitogenic signaling by PDGF is coincident with tyrosine phosphorylation of PLC-gamma.

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Platelet-derived growth factor stimulates formation of active p21ras.GTP complex in Swiss mouse 3T3 cells.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.87.15.5993 ◽

1990 ◽

Vol 87 (15) ◽

pp. 5993-5997 ◽

Cited By ~ 139

Author(s):

T. Satoh ◽

M. Endo ◽

M. Nakafuku ◽

S. Nakamura ◽

Y. Kaziro

Keyword(s):

Growth Factor ◽

Platelet Derived Growth Factor ◽

Swiss Mouse ◽

3T3 Cells

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v-Src increases diacylglycerol levels via a type D phospholipase-mediated hydrolysis of phosphatidylcholine

Molecular and Cellular Biology ◽

10.1128/mcb.11.10.4903-4908.1991 ◽

1991 ◽

Vol 11 (10) ◽

pp. 4903-4908

Author(s):

J G Song ◽

L M Pfeffer ◽

D A Foster

Keyword(s):

Arachidonic Acid ◽

Tyrosine Kinase ◽

Phosphatidic Acid ◽

Signaling Pathway ◽

Myristic Acid ◽

Protein Tyrosine Kinase ◽

Second Messenger ◽

3T3 Cells ◽

Type D ◽

Hydrolysis Of

Activating the protein-tyrosine kinase of v-Src in BALB/c 3T3 cells results in rapid increases in the intracellular second messenger, diacylglycerol (DAG). v-Src-induced increases in radiolabeled DAG were most readily detected when phospholipids were prelabeled with myristic acid, which is incorporated predominantly into phosphatidylcholine. Consistent with this observation, v-Src increased the level of intracellular choline. No increase in DAG was observed when cells were prelabeled with arachidonic acid, which is incorporated predominantly into phosphatidylinositol. Inhibiting phosphatidic acid (PA) phosphatase, which hydrolyzes PA to DAG, blocked v-Src-induced DAG production and enhanced PA production, implicating a type D phospholipase. Consistent with the involvement of a type D phospholipase, v-Src increased transphosphatidylation activity, which is characteristic of type D phospholipases. Thus, v-Src-induced increases in DAG most likely result from the activation of a type D phospholipase/PA phosphatase-mediated signaling pathway.

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