title: Colony-stimulating factor-1 (CSF-1) receptor-mediated macrophage differentiation in myeloid cells: a role for tyrosine 559-dependent protein phosphatase 2A (PP2A) activity.
abstract: M1 myeloid cells transfected with the wild-type (WT) colony-stimulating factor-1 (CSF-1) receptor (CSF-1R; M1/WT cells) undergo CSF-1-dependent macrophage differentiation. By mutation studies, we have provided prior evidence that tyrosine 559 in the CSF-1R cytoplasmic domain governs the Src-dependent differentiation pathway. Further components of this pathway were then sought. We report that the extent of CSF-1-mediated tyrosine phosphorylation of protein phosphatase 2A (PP2A), and the associated loss of its activity were reduced in M1 cells transfected with the CSF-1R with a tyrosine-to-phenylalanine mutation at position 559 (M1/559 cells), compared with the corresponding responses in CSF-1-treated M1/WT cells. This evidence for an involvement of a reduction in PP2A activity in the differentiation process was supported by the restoration of the defect in the CSF-1-mediated differentiation of M1/559 cells by the addition of the PP2A inhibitor, okadaic acid. It was also found that the degree of activation of extracellular-signal-regulated kinase (ERK) activities by CSF-1 was reduced in M1/559 cells, suggesting their involvement in the differentiation process. These data suggest that PP2A and ERK form part of the Src-dependent signal-transduction cascade governing CSF-1-mediated macrophage differentiation in M1 cells.
authors.affiliation: Arthritis and Inflammation Research Centre, University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Parkville, Victoria, Australia. kerrie_ann_mcmahon@hotmail.com
authors.forename: K A
authors.initials: KA
authors.lastname: McMahon
authors.forename: N J
authors.initials: NJ
authors.lastname: Wilson
authors.forename: D C
authors.initials: DC
authors.lastname: Marks
authors.forename: T L
authors.initials: TL
authors.lastname: Beecroft
authors.forename: G A
authors.initials: GA
authors.lastname: Whitty
authors.forename: J A
authors.initials: JA
authors.lastname: Hamilton
authors.forename: X F
authors.initials: XF
authors.lastname: Csar
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000502:physiology*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation; D022423:Myeloid Cells / Q000166:cytology* / Q000187:drug effects; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D054648:Protein Phosphatase 2; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D004791:Enzyme Inhibitors; D019319:Okadaic Acid; D019000:Phosphotyrosine; D016186:Receptor, Macrophage Colony-Stimulating Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2