Roles of PU.1 in monocyte- and mast cell-specific gene regulation: PU.1 transactivates CIITA pIV in cooperation with IFN-gamma

Int Immunol. 2009 Jul;21(7):803-16. doi: 10.1093/intimm/dxp048. Epub 2009 Jun 5.

Abstract

Over-expression of PU.1, a myeloid- and lymphoid-specific transcription factor belonging to the Ets family, induces monocyte-specific gene expression in mast cells. However, the effects of PU.1 on each target gene and the involvement of cytokine signaling in PU.1-mediated gene expression are largely unknown. In the present study, PU.1 was over-expressed in two different types of bone marrow-derived cultured mast cells (BMMCs): BMMCs cultured with IL-3 plus stem cell factor (SCF) and BMMCs cultured with pokeweed mitogen-stimulated spleen-conditioned medium (PWM-SCM). PU.1 over-expression induced expression of MHC class II, CD11b, CD11c and F4/80 on PWM-SCM-cultured BMMCs, whereas IL-3/SCF-cultured BMMCs expressed CD11b and F4/80, but not MHC class II or CD11c. When IFN-gamma was added to the IL-3/SCF-based medium, PU.1 transfectant acquired MHC class II expression, which was abolished by antibody neutralization or in Ifngr(-/-) BMMCs, through the induction of expression of the MHC class II transactivator, CIITA. Real-time PCR detected CIITA mRNA driven by the fourth promoter, pIV, and chromatin immunoprecipitation indicated direct binding of PU.1 to pIV in PU.1-over-expressing BMMCs. PU.1-over-expressing cells showed a marked increase in IL-6 production in response to LPS stimulation in both IL-3/SCF and PWM-SCM cultures. These results suggest that PU.1 overproduction alone is sufficient for both expression of CD11b and F4/80 and for amplification of LPS-induced IL-6 production. However, IFN-gamma stimulation is essential for PU.1-mediated transactivation of CIITA pIV. Reduced expression of mast cell-related molecules and transcription factors GATA-1/2 and up-regulation of C/EBPalpha in PU.1 transfectants indicate that enforced PU.1 suppresses mast cell-specific gene expression through these transcription factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Differentiation / immunology
  • Antigens, Differentiation / metabolism
  • CD11b Antigen / immunology
  • CD11b Antigen / metabolism
  • CD11c Antigen / immunology
  • CD11c Antigen / metabolism
  • Culture Media, Conditioned / pharmacology
  • Genes, MHC Class II
  • Humans
  • Interferon-gamma / immunology*
  • Interferon-gamma / pharmacology
  • Interleukin-3 / pharmacology
  • Interleukin-4 / pharmacology
  • Interleukin-6 / biosynthesis
  • Interleukin-6 / immunology
  • Lipopolysaccharides / pharmacology
  • Mast Cells / drug effects
  • Mast Cells / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Nuclear Proteins / genetics
  • Proteins / pharmacology
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Receptors, Interferon / genetics
  • Receptors, Interferon / immunology
  • Receptors, Interferon / metabolism
  • Stem Cell Factor / pharmacology
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcriptional Activation*
  • Tumor Necrosis Factor-alpha / pharmacology
  • fms-Like Tyrosine Kinase 3 / pharmacology

Substances

  • Antigens, Differentiation
  • CD11b Antigen
  • CD11c Antigen
  • Culture Media, Conditioned
  • Interleukin-3
  • Interleukin-6
  • Lipopolysaccharides
  • MHC class II transactivator protein
  • Nuclear Proteins
  • Proteins
  • Proto-Oncogene Proteins
  • Receptors, Interferon
  • Stem Cell Factor
  • Trans-Activators
  • Tumor Necrosis Factor-alpha
  • monocyte-macrophage differentiation antigen
  • proto-oncogene protein Spi-1
  • serum cancer-suppressive peptide, mouse
  • interferon gamma receptor
  • Interleukin-4
  • Interferon-gamma
  • Flt3 protein, mouse
  • fms-Like Tyrosine Kinase 3