title: Increased CCAAT enhancer-binding protein epsilon (C/EBPepsilon) expression and premature apoptosis in myeloid cells expressing Gfi-1 N382S mutant associated with severe congenital neutropenia.
abstract: Granulocyte-colony-stimulating factor (G-CSF) stimulates the activation of multiple signaling pathways, leading to alterations in the activities of transcription factors. Gfi-1 is a zinc finger transcriptional repressor that is required for granulopoiesis. How Gfi-1 acts in myeloid cells is poorly understood. We show here that the expression of Gfi-1 was up-regulated during G-CSF-induced granulocytic differentiation in myeloid 32D cells. Truncation of the carboxyl terminus of the G-CSF receptor, as seen in patients with acute myeloid leukemia evolving from severe congenital neutropenia, disrupted Gfi-1 up-regulation by G-CSF. Ectopic expression of a dominant negative Gfi-1 mutant, N382S, which was associated with severe congenital neutropenia, resulted in premature apoptosis and reduced proliferation of cells induced to differentiate with G-CSF. The expression of neutrophil elastase (NE) and CCAAT enhancer-binding protein epsilon (C/EBPepsilon) was significantly increased in 32D cells expressing N382S. In contrast, overexpression of wild type Gfi-1 abolished G-CSF-induced up-regulation of C/EBPepsilon but had no apparent effect on NE up-regulation by G-CSF. Notably, G-CSF-dependent proliferation and survival were inhibited upon overexpression of C/EBPepsilon but not NE. These data indicate that Gfi-1 down-regulates C/EBPepsilon expression and suggest that increased expression of C/EBPepsilon as a consequence of loss of Gfi-1 function may be deleterious to the proliferation and survival of early myeloid cells.
authors.affiliation: Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606, USA.
authors.forename: Dazhong
authors.initials: D
authors.lastname: Zhuang
authors.forename: Yaling
authors.initials: Y
authors.lastname: Qiu
authors.forename: Scott C
authors.initials: SC
authors.lastname: Kogan
authors.forename: Fan
authors.initials: F
authors.lastname: Dong
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D022762:CCAAT-Enhancer-Binding Proteins / Q000096:biosynthesis*; D002453:Cell Cycle; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D004247:DNA / Q000378:metabolism; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D016179:Granulocyte Colony-Stimulating Factor / Q000378:metabolism; D006098:Granulocytes / Q000378:metabolism; D007377:Interleukin-3 / Q000378:metabolism; D051379:Mice; D009154:Mutation; D022423:Myeloid Cells / Q000378:metabolism*; D009503:Neutropenia / Q000151:congenital*; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation; D016335:Zinc Fingers
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C489468:Cebpe protein, mouse; D004268:DNA-Binding Proteins; C079873:Gfi1 protein, mouse; D007377:Interleukin-3; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D014157:Transcription Factors; D016179:Granulocyte Colony-Stimulating Factor; D004247:DNA