C/EBPalpha directs monocytic commitment of primary myeloid progenitors.
C/EBPalpha is required for generation of granulocyte-monocyte progenitors, but the subsequent role of C/EBPalpha in myeloid lineage commitment remains uncertain. We transduced murine marrow cells with C/EBPalpha-estradiol receptor (ER) or empty vector and subjected these to lineage depletion just prior to culture in estradiol with myeloid cytokines. This protocol limits biases due to lineage-specific effects on developmental kinetics, proliferation, and apoptosis. Also, lowering the dose of estradiol reduced activated C/EBPalpha-ER to near the physiologic range. C/EBPalpha-ER increased Mac1(+)/Gr1(-)/MPO(-)/low monocytes 1.9-fold while reducing Mac1(+)/Gr1(+)/MPO(hi) granulocytes 2.5-fold at 48 hours, even in 0.01 microM estradiol. This pattern was confirmed morphologically and by quantitative polymerase chain reaction (PCR) assay of lineage markers. To directly assess effects on immature progenitors, transduced cells were cultured for 1 day with and then in methylcellulose without estradiol. A 2-fold increase in monocytic compared with granulocytic colonies was observed in IL-3/IL-6/SCF or GM-CSF, but not G-CSF, even in 0.01 microM estradiol. C/EBPalpha-ER induced PU.1 mRNA, and PU.1-ER stimulated monocytic development, suggesting that transcriptional induction of PU.1 by C/EBPalpha contributes to monopoiesis. A C/EBPalpha variant incapable of zippering with c-Jun did not induce monopoiesis, and a variant unable to bind NF-kappaB p50 stimulated granulopoiesis, suggesting their cooperation with C/EBPalpha during monocytic commitment.
Wang
Dehua
D
Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD 21231, USA.
D'Costa
Jenice
J
Civin
Curt I
CI
Friedman
Alan D
AD
D000818:Animals; D000943:Antigens, Differentiation / Q000096:biosynthesis; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D004958:Estradiol / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D016758:Genes, jun / Q000235:genetics; D042381:Granulocyte Precursor Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D023461:Myeloid Progenitor Cells; D038042:Myelopoiesis / Q000187:drug effects / Q000235:genetics; D052002:NF-kappa B p50 Subunit / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D011959:Receptors, Estradiol / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D015534:Trans-Activators / Q000096:biosynthesis; D014161:Transduction, Genetic; D000099232:Proto-Oncogene Protein Spi-1
D000943:Antigens, Differentiation; D022763:CCAAT-Enhancer-Binding Protein-alpha; D016207:Cytokines; D004958:Estradiol; D052002:NF-kappa B p50 Subunit; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011959:Receptors, Estradiol; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1