Type I IFNs downregulate myeloid cell IFN-γ receptor by inducing recruitment of an early growth response 3/NGFI-A binding protein 1 complex that silences ifngr1 transcription

J Immunol. 2013 Sep 15;191(6):3384-92. doi: 10.4049/jimmunol.1203510. Epub 2013 Aug 9.

Abstract

The ability of type I IFNs to increase susceptibility to certain bacterial infections correlates with downregulation of myeloid cell surface IFNGR, the receptor for the type II IFN (IFN-γ), and reduced myeloid cell responsiveness to IFN-γ. In this study, we show that the rapid reductions in mouse and human myeloid cell surface IFNGR1 expression that occur in response to type I IFN treatment reflect a rapid silencing of new ifngr1 transcription by repressive transcriptional regulators. Treatment of macrophages with IFN-β reduced cellular abundance of ifngr1 transcripts as rapidly and effectively as actinomycin D treatment. IFN-β treatment also significantly reduced the amounts of activated RNA polymerase II (pol II) and acetylated histones H3 and H4 at the ifngr1 promoter and the activity of an IFNGR1-luc reporter construct in macrophages. The suppression of IFNGR1-luc activity required an intact early growth response factor (Egr) binding site in the proximal ifngr1 promoter. Three Egr proteins and two Egr/NGFI-A binding (Nab) proteins were found to be expressed in bone macrophages, but only Egr3 and Nab1 were recruited to the ifngr1 promoter upon IFN-β stimulation. Knockdown of Nab1 in a macrophage cell line prevented downregulation of IFNGR1 and prevented the loss of acetylated histones from the ifngr1 promoter. These data suggest that type I IFN stimulation induces a rapid recruitment of a repressive Egr3/Nab1 complex that silences transcription from the ifngr1 promoter. This mechanism of gene silencing may contribute to the anti-inflammatory effects of type I IFNs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Chromatin Immunoprecipitation
  • Down-Regulation
  • Early Growth Response Protein 3 / immunology
  • Early Growth Response Protein 3 / metabolism*
  • Flow Cytometry
  • Gene Silencing / physiology*
  • Humans
  • Interferon Type I / immunology
  • Interferon Type I / metabolism*
  • Interferon gamma Receptor
  • Macrophages / immunology
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Myeloid Cells / immunology
  • Myeloid Cells / metabolism
  • Real-Time Polymerase Chain Reaction
  • Receptors, Interferon / immunology
  • Receptors, Interferon / metabolism*
  • Repressor Proteins / immunology
  • Repressor Proteins / metabolism*
  • Transcription, Genetic

Substances

  • Interferon Type I
  • NAB1 protein, human
  • Nab1 protein, mouse
  • Receptors, Interferon
  • Repressor Proteins
  • Early Growth Response Protein 3