Activated Fes protein tyrosine kinase induces terminal macrophage differentiation of myeloid progenitors (U937 cells) and activation of the transcription factor PU.1.
The c-fps/fes proto-oncogene encodes a 92-kDa protein tyrosine kinase that is preferentially expressed in myeloid and endothelial cells. Fes is believed to play a role in vascular development and myelopoiesis and in the inflammatory responses of granulocytes and macrophages. To help define the biological role of this kinase and identify its downstream targets, we have developed a gain-of-function allele of Fes that has potent biological activity in myeloid cell progenitors. Introduction of constitutively active Fes into bipotential U937 cells induced the appearance of fully differentiated macrophages within 6 to 12 days. The Fes-expressing differentiated cells became adherent, had distinctive macrophage morphology, and exhibited increased expression of myelomonocytic differentiation markers, including CD11b, CD11c, CD18, CD14, and the macrophage colony-stimulating factor receptor. These cells acquired phagocytic properties and exhibited NADPH oxidase and nonspecific esterase activities, confirming that they were functionally active macrophages. Concomitantly, there was downregulation of the granulocytic marker granulocyte colony-stimulating factor receptor, indicating that the biological activity of Fes was coordinated in a lineage-specific manner. A constitutively active Src did not induce macrophage morphology or upregulation of myelomonocytic markers in U937 cells, suggesting that the biological activity we observed was not a general consequence of expression of an activated nonreceptor tyrosine kinase. Analysis of possible downstream targets of Fes revealed that this kinase activated the ets family transcription factor PU.1, which is essential for macrophage development. Our results strongly implicate Fes as a key regulator of terminal macrophage differentiation and identify PU.1 as a transcription factor that may mediate some of its biological activities in myeloid cells.
Kim
Jynho
J
Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Feldman
Ricardo A
RA
D000483:Alleles; D015703:Antigens, CD / Q000096:biosynthesis; D000943:Antigens, Differentiation / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D015681:Fusion Proteins, gag-onc / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010641:Phenotype; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D013925:Thromboplastin / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection; D020298:U937 Cells; D000099232:Proto-Oncogene Protein Spi-1
D015703:Antigens, CD; D000943:Antigens, Differentiation; D015681:Fusion Proteins, gag-onc; D011505:Protein-Tyrosine Kinases; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D013925:Thromboplastin; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C000715470:MAS1 protein, human; C068415:v-fps oncogene protein, Fujinami sarcoma virus