title: Association between phosphatidylinositol-3 kinase, Cbl and other tyrosine phosphorylated proteins in colony-stimulating factor-1-stimulated macrophages.
abstract: Colony stimulating factor-1 (CSF-1) stimulation of the macrophage cell line BAC1.2F5 and murine bone marrow-derived macrophages resulted in tyrosine phosphorylation of phosphatidylinositol-3 kinase (PI-3 kinase) p85 alpha and its stable association with several tyrosine phosphorylated proteins, including CSF-1 receptor (p165), p120, p95 and p55-p60. p120 co-migrated with the product of the protooncogene c-cb1 in anti-p85 alpha immunoprecipitates, and associated with p85 alpha in a rapid and transient manner. Reciprocal experiments confirmed the presence of p85 alpha in anti-Cb1 immunoprecipitates on CSF-1 stimulation of macrophages. PI-3 kinase immunoprecipitates from the myeloid FDC-P1 cell line expressing mutant CSF-1 receptor (Y721F), which does not associate with PI-3 kinase, still contained Cbl. The identity of the tyrosine phosphorylated protein p95 remains unknown. The interaction between p85 alpha and the tyrosine phosphorylated proteins survived anion-exchange chromatography, suggesting perhaps the presence of a stable complex; furthermore, in CSF-1-treated BAC1.2F5 cell extracts, only one of the two pools of PI-3 kinase separated by chromatography was present in this putative complex. The association did not appear to correlate with proliferation, since a similar interaction between p85 alpha and tyrosine phosphorylated proteins was also observed in poorly proliferating resident peritoneal macrophages stimulated with CSF-1. The possible significance of these findings for CSF-1-regulated macrophage functions is discussed.
authors.affiliation: University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: V
authors.initials: V
authors.lastname: Kanagasundaram
authors.forename: A
authors.initials: A
authors.lastname: Jaworowski
authors.forename: J A
authors.initials: JA
authors.lastname: Hamilton
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002852:Chromatography, Ion Exchange; D008262:Macrophage Activation; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011233:Precipitin Tests; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D013462:Sulfur Radioisotopes; D014443:Tyrosine / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D011518:Proto-Oncogene Proteins; D013462:Sulfur Radioisotopes; D014443:Tyrosine; D016173:Macrophage Colony-Stimulating Factor; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); C493849:Cbl protein, mouse