Granulocyte colony-stimulating factor regulates myeloid differentiation through CCAAT/enhancer-binding protein epsilon.
Granulocyte colony-stimulating factor (G-CSF) is a major cytokine that regulates proliferation and differentiation of myeloid cells, although the underlying mechanisms by which G-CSF controls myeloid differentiation are largely unknown. Differentiation of hematopoietic cells is regulated by lineage-specific transcription factors, and gene-targeting studies previously revealed the critical roles of CCAAT/enhancer-binding protein (C/EBP) alpha and C/EBP epsilon, respectively, in the early and mid-late stages of granulocyte differentiation. The expression of C/EBP epsilon in 32Dcl3 cells and FDCP1 cells expressing mutant G-CSF receptors was examined and it was found that G-CSF up-regulates C/EBP epsilon. The signal for this expression required the region containing the first tyrosine residue of G-CSF receptor. Dominant-negative signal transducers and activators of transcription 3 blocked G-CSF--induced granulocytic differentiation in 32D cells but did not block induction of C/EBP epsilon, indicating that these proteins work in different pathways. It was also found that overexpression of C/EBP epsilon greatly facilitated granulocytic differentiation by G-CSF and, surprisingly, that expression of C/EBP epsilon alone was sufficient to make cells differentiate into morphologically and functionally mature granulocytes. Overexpression of c-myc inhibits differentiation of hematopoietic cells, but the molecular mechanisms of this inhibition are not fully understood. In 32Dcl3 cells overexpressing c-myc that do not differentiate by means of G-CSF, induction of C/EBP epsilon is completely abrogated. Ectopic expression of C/EBP epsilon in these cells induced features of differentiation, including changes in nuclear morphologic characteristics and the appearance of granules. These data show that C/EBP epsilon constitutes a rate-limiting step in G-CSF-regulated granulocyte differentiation and that c-myc antagonizes G-CSF-induced myeloid differentiation, at least partly by suppressing induction of C/EBP epsilon. (Blood. 2001;98:897-905)
Nakajima
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Howard Hughes Medical Institute, Department of Biochemistry, St Jude Children's Research Hospital, Memphis, TN, USA. hnakajim@med.keio.ac.jp
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D000818:Animals; D023081:CCAAT-Binding Factor / Q000494:pharmacology*; D022762:CCAAT-Enhancer-Binding Proteins / Q000187:drug effects / Q000494:pharmacology* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000494:pharmacology; D004347:Drug Interactions; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006098:Granulocytes / Q000166:cytology / Q000187:drug effects; D051379:Mice; D022423:Myeloid Cells / Q000166:cytology* / Q000187:drug effects; D016271:Proto-Oncogene Proteins c-myc / Q000494:pharmacology; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
D023081:CCAAT-Binding Factor; D022762:CCAAT-Enhancer-Binding Proteins; C489468:Cebpe protein, mouse; D004268:DNA-Binding Proteins; D016271:Proto-Oncogene Proteins c-myc; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D016179:Granulocyte Colony-Stimulating Factor