Sequential activation of phoshatidylinositol 3-kinase and phospholipase C-gamma2 by the M-CSF receptor is necessary for differentiation signaling.
Binding of macrophage colony stimulating factor (M-CSF) to its receptor (Fms) induces dimerization and activation of the tyrosine kinase domain of the receptor, resulting in autophosphorylation of cytoplasmic tyrosine residues used as docking sites for SH2-containing signaling proteins that relay growth and development signals. To determine whether a distinct signaling pathway is responsible for the Fms differentiation signal versus the growth signal, we sought new molecules involved in Fms signaling by performing a two-hybrid screen in yeast using the autophosphorylated cytoplasmic domain of the wild-type Fms receptor as bait. Clones containing SH2 domains of phospholipase C-gamma2 (PLC-gamma2) were frequently isolated and shown to interact with phosphorylated Tyr721 of the Fms receptor, which is also the binding site of the p85 subunit of phosphatidylinositol 3-kinase (PI3-kinase). At variance with previous reports, M-CSF induced rapid and transient tyrosine phosphorylation of PLC-gamma2 in myeloid FDC-P1 cells and this activation required the activity of the PI3-kinase pathway. The Fms Y721F mutation strongly decreased this activation. Moreover, the Fms Y807F mutation decreased both binding and phosphorylation of PLC-gamma2 but not that of p85. Since the Fms Y807F mutation abrogates the differentiation signal when expressed in FDC-P1 cells and since this phenotype could be reproduced by a specific inhibitor of PLC-gamma, we propose that a balance between the activities of PLC-gamma2 and PI3-kinase in response to M-CSF is required for cell differentiation.
Bourette
R P
RP
Fred Hutchinson Cancer Research Center, Basic Sciences Division, Room B2-152, 1100 Fairview Avenue-N., Seattle, WA 98109-1024, USA.
Myles
G M
GM
Choi
J L
JL
Rohrschneider
L R
LR
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D004789:Enzyme Activation; D004963:Estrenes / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051966:Phospholipase C gamma; D010766:Phosphorylation; D011760:Pyrrolidinones / Q000494:pharmacology; D011817:Rabbits; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains
D004963:Estrenes; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D010726:Phosphodiesterase Inhibitors; D051966:Phospholipase C gamma; D011760:Pyrrolidinones; D016186:Receptor, Macrophage Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D010738:Type C Phospholipases; D014443:Tyrosine; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione