A composite C/EBP binding site is essential for the activity of the promoter of the IL-3/IL-5/granulocyte-macrophage colony-stimulating factor receptor beta c gene.
The common beta-chain (beta c) is the main signaling component of the heterodimeric receptors for IL-3, IL-5, and GM-CSF and is primarily expressed on myeloid cells. The proximal beta c promoter is regulated by GGAA binding proteins, including PU.1, a hemopoietic specific member of the Ets family. However, it is not likely that PU.1 alone accounts for the myeloid-restricted expression of the beta c subunit. Here we describe the identification of a C/EBP binding enhancer that is located 2 kb upstream of the transcription start site. The enhancer contains two elements that bind C/EBP alpha and -beta in U937 cells, while C/EBP epsilon is also bound in extracts of HL-60 cells. Importantly, deletion of the enhancer or mutation of either of one of the C/EBP sites results in a complete loss of promoter activity in cell lines as well as in primary cells, showing the importance of C/EBP members in beta c gene activation. We further show that PU.1 has to cooperate with C/EBP proteins to induce beta c transcription. Since the beta c is already expressed on CD34+ cells, these results demonstrate that both C/EBP and PU.1 are not only important for the myeloid-specific gene regulation at later stages of myeloid differentiation.
van Dijk
T B
TB
Department of Pulmonary Diseases, University Hospital Utrecht, The Netherlands.
Baltus
B
B
Raaijmakers
J A
JA
Lammers
J W
JW
Koenderman
L
L
de Groot
R P
RP
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins; D019556:COS Cells; D053648:Cytokine Receptor Common beta Subunit; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D004357:Drug Synergism; D004742:Enhancer Elements, Genetic / Q000276:immunology*; D005786:Gene Expression Regulation / Q000276:immunology; D018922:HL-60 Cells; D006801:Humans; D015848:Interleukin-5 / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism* / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000276:immunology*; D011518:Proto-Oncogene Proteins / Q000502:physiology; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics* / Q000378:metabolism; D016185:Receptors, Interleukin-3 / Q000235:genetics* / Q000378:metabolism; D053649:Receptors, Interleukin-5; D015534:Trans-Activators / Q000502:physiology; D015533:Transcriptional Activation; D020298:U937 Cells; D000099232:Proto-Oncogene Protein Spi-1
D022762:CCAAT-Enhancer-Binding Proteins; D053648:Cytokine Receptor Common beta Subunit; D004268:DNA-Binding Proteins; D015848:Interleukin-5; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D018123:Receptors, Interleukin; D016185:Receptors, Interleukin-3; D053649:Receptors, Interleukin-5; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C115876:CSF2RB protein, human