Modulation of phosphoinositide 3-kinase activation by cholesterol level suggests a novel positive role for lipid rafts in lysophosphatidic acid signalling.
Methyl-beta-cyclodextrin (MbetaCD) was used to explore a role for cholesterol-enriched plasma membrane microdomains in coupling lysophosphatidic acid (LPA) stimulation to phosphoinositide 3-kinase (PI3K) activation. Cholesterol depletion strongly inhibited the production of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate in Vero cells stimulated with LPA. In agreement, the phosphorylation of Akt/protein kinase B, but not of Erk kinases, was suppressed by MbetaCD. MbetaCD did not interfere with the overall phospholipid metabolism, and its effects were reversed in cholesterol add-back experiments. Finally, PI3K was detected in lipid rafts prepared from control but not MbetaCD-treated cells, suggesting that these microdomains contribute to LPA signalling by compartmentalising component(s) of the PI3K pathway.
Peres
Christine
C
INSERM U563, Department of Lipoproteins and Lipid Mediators, IFR 30, Hôpital Purpan, 31059 Toulouse, France.
Yart
Armelle
A
Perret
Bertrand
B
Salles
Jean Pierre
JP
Raynal
Patrick
P
D000818:Animals; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000378:metabolism* / Q000494:pharmacology; D003505:Cyclodextrins / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism; D050356:Lipid Metabolism; D008246:Lysophospholipids / Q000378:metabolism* / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D014709:Vero Cells / Q000187:drug effects; D047392:beta-Cyclodextrins
D002784:Cholesterol; D003505:Cyclodextrins; D066246:ErbB Receptors; D008246:Lysophospholipids; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D010743:Phospholipids; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C060974:phosphatidylinositol 3,4,5-triphosphate; C060980:phosphatidylinositol 3,4-diphosphate