BRCA1 regulates IFN-gamma signaling through a mechanism involving the type I IFNs

Mol Cancer Res. 2007 Mar;5(3):261-70. doi: 10.1158/1541-7786.MCR-06-0250.

Abstract

BRCA1 encodes a tumor suppressor gene that is mutated in the germ line of women with a genetic predisposition to breast and ovarian cancer. BRCA1 has been implicated in a number of important cellular functions including DNA damage repair, transcriptional regulation, cell cycle control, and ubiquitination. Using an Affymetrix U95A microarray, IRF-7 was identified as a BRCA1 transcriptional target and was also shown to be synergistically up-regulated by BRCA1 specifically in the presence of IFN-gamma, coincident with the synergistic induction of apoptosis. We show that BRCA1, signal transducer and activator of transcription (STAT)-1, and STAT2 are all required for the induction of IRF-7 following stimulation with IFN-gamma. We also show that the induction of IRF-7 by BRCA1 and IFN-gamma is dependent on the type I IFNs, IFN-alpha and IFN-beta. We show that BRCA1 is required for the up-regulation of STAT1, STAT2, and the type I IFNs in response to IFN-gamma. We show that BRCA1 is localized at the promoters of the molecules involved in type I IFN signaling leading to their up-regulation. Blocking this intermediary type I IFN step using specific antisera shows the requirement for IFN-alpha and IFN-beta in the induction of IRF-7 and apoptosis. Finally, we outline a mechanism for the BRCA1/IFN-gamma regulation of target genes involved in the innate immune response, which is dependent on type I IFN signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • BRCA1 Protein / analysis
  • BRCA1 Protein / metabolism*
  • Cell Line, Tumor
  • Cell Proliferation
  • Humans
  • Immunity, Innate / genetics*
  • Interferon Regulatory Factor-7 / genetics*
  • Interferon Type I / antagonists & inhibitors
  • Interferon Type I / metabolism*
  • Interferon Type I / pharmacology
  • Interferon-gamma / pharmacology*
  • Promoter Regions, Genetic
  • STAT1 Transcription Factor / genetics
  • STAT1 Transcription Factor / metabolism
  • STAT2 Transcription Factor / genetics
  • STAT2 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / immunology
  • Up-Regulation

Substances

  • BRCA1 Protein
  • IRF7 protein, human
  • Interferon Regulatory Factor-7
  • Interferon Type I
  • STAT1 Transcription Factor
  • STAT2 Transcription Factor
  • Interferon-gamma