Phospholipase C-gamma, a substrate for PDGF receptor kinase, is not phosphorylated on tyrosine during the mitogenic response to CSF-1.
Quiescent mouse NIH3T3 cells expressing a transduced human c-fms gene encoding the receptor for colony stimulating factor-1 (CSF-1) were stimulated with mitogenic concentrations of platelet-derived growth factor (PDGF) or CSF-1. Immunoprecipitated phospholipase C-gamma (PLC-gamma) was phosphorylated on tyrosine and calcium was mobilized following treatment of intact cells with PDGF. In contrast, only trace amounts of phosphotyrosine were incorporated into PLC-gamma and no intracellular calcium signal was detected after CSF-1 stimulation. Similarly, CSF-1 treatment did not stimulate phosphorylation of PLC-gamma on tyrosine in a CSF-1-dependent. SV40-immortalized mouse macrophage cell line that expresses high levels of the CSF-1 receptor. In fibroblasts, antiserum to PLC-gamma co-precipitated a fraction of the tyrosine phosphorylated form of the PDGF receptor (PDGF-R) after ligand stimulation, implying that phosphorylated PDGF-R and PLC-gamma were associated in a stable complex. Pre-treatment of cells with orthovanadate also led to tyrosine phosphorylation of PLC-gamma which was significantly enhanced by PDGF, but not by CSF-1. Thus, although the PDGF and CSF-1 receptors are structurally related and appear to be derived from a single ancestor gene, only PDGF-induced mitogenesis in fibroblasts correlated with tyrosine phosphorylation of PLC-gamma.
Downing
J R
JR
Department of Tumor Cell Biology, St Jude Children's Research Hospital, Memphis, TN 38105.
Margolis
B L
BL
Zilberstein
A
A
Ashmun
R A
RA
Ullrich
A
A
Sherr
C J
CJ
Schlessinger
J
J
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003115:Colony-Stimulating Factors / Q000494:pharmacology*; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008934:Mitogens / Q000494:pharmacology; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism / Q000494:pharmacology; D011519:Proto-Oncogenes; D011956:Receptors, Cell Surface / Q000378:metabolism; D016184:Receptors, Colony-Stimulating Factor; D017479:Receptors, Platelet-Derived Growth Factor; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D003115:Colony-Stimulating Factors; D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D016184:Receptors, Colony-Stimulating Factor; D014443:Tyrosine; D016173:Macrophage Colony-Stimulating Factor; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D010738:Type C Phospholipases; D002118:Calcium