CCAAT/enhancer-binding protein activates the CD14 promoter and mediates transforming growth factor beta signaling in monocyte development.
Transcription factors from the CCAAT/enhancer-binding protein (C/EBP) family play important roles in myeloid cell differentiation. CD14 is a monocyte/macrophage differentiation marker and is strongly up-regulated during monocytic cell differentiation. Here, we report the direct binding of C/EBP to the monocyte-specific promoter of CD14. Transactivation analyses demonstrate that C/EBP family members significantly activate the CD14 promoter. These data indicate that C/EBP is directly involved in the regulation of CD14 gene expression. When myelomonoblastic U937 cells are treated with vitamin D(3) and TGF-beta, they differentiate toward monocytic cells. Using specific antibodies against different C/EBP family members in electrophoretic mobility shift assays and Western blot assays, we have identified a specific increase in the DNA binding and the expression of C/EBPalpha and C/EBPbeta during U937 monocytic cell differentiation, and we found C/EBPalpha and C/EBPbeta bind to the promoter in heterodimer. Furthermore, with stably transfected cell lines, we demonstrate that the C/EBP binding site in the CD14 promoter plays a critical role for mediating TGF-beta signaling in the synergistic activation of CD14 expression by vitamin D(3) and TGF-beta during U937 differentiation. This may indicate that C/EBPs have important functions in the process of TGF-beta signal transduction during monocyte differentiation.
Pan
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Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
Hetherington
C J
CJ
Zhang
D E
DE
D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002454:Cell Differentiation; D002762:Cholecalciferol / Q000378:metabolism; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000235:genetics*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015398:Signal Transduction; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D020298:U937 Cells
D022762:CCAAT-Enhancer-Binding Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D018950:Lipopolysaccharide Receptors; D009687:Nuclear Proteins; D016212:Transforming Growth Factor beta; D002762:Cholecalciferol