Cooperation between PU.1 and CAAT/enhancer-binding protein beta is necessary to induce the expression of the MD-2 gene.
Myeloid differentiation factor 2 (MD-2) binds Gram-negative bacterial lipopolysaccharide with high affinity and is essential for Toll-like receptor 4-dependent signal transduction. MD-2 has recently been recognized as a type II acute phase protein. Plasma concentrations of the soluble form of MD-2 increase markedly during the course of severe infections. Its production is regulated in hepatocytes and myeloid cells by interleukin-6 (IL-6) but not IL-1beta. In the present work we show that two transcription factors (TF), PU.1 and CAAT/enhancer-binding protein beta (C/EBPbeta), participate in the activation of the human MD-2 gene in hepatocytic cells after stimulation with IL-6. PU.1 TF and proximal PU.1 binding sites in the MD-2 promoter were shown to be critical for the basal activity of the promoter as well as for IL-6-induced soluble MD-2 production. Deletions of proximal portions of the MD-2 promoter containing PU.1 and/or NF-IL-6 consensus binding sites as well as site-directed mutagenesis of these binding sites abrogated IL-6-dependent MD-2 gene activation. We show that the cooperation between C/EBPbeta and PU.1 is critical for the transcriptional activation of the MD-2 gene by IL-6. PU.1 was essentially known as a TF involved in the differentiation of myeloid precursor cells and the expression of surface receptors of the innate immunity. Herein, we show that it also participates in the regulation of an acute phase protein, MD-2, in nonmyeloid cells cooperatively with C/EBPbeta, a classical IL-6-inducible TF.
Tissières
Pierre
P
Intensive Care, University Hospitals of Geneva, Geneva 14, Switzerland.
Araud
Tanguy
T
Ochoda
Agnieszka
A
Drifte
Geneviève
G
Dunn-Siegrist
Irène
I
Pugin
Jérôme
J
D017398:Alternative Splicing; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D005786:Gene Expression Regulation; D018922:HL-60 Cells; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051218:Lymphocyte Antigen 96 / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009154:Mutation; D022423:Myeloid Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D000099232:Proto-Oncogene Protein Spi-1
D022782:CCAAT-Enhancer-Binding Protein-beta; D015850:Interleukin-6; D008156:Luciferases; D051218:Lymphocyte Antigen 96; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C495377:LY96 protein, human