STAT-1α and IFN-γ as Modulators of TNF-α Signaling in Macrophages: Regulation and Functional Implications of the TNF Receptor 1:STAT-1α Complex

Academic Article

Abstract

  • TNF-α and IFN-γ cooperate in the activation of macrophages. TNF-α-dependent activation of NF-κB is stronger in the presence of IFN-γ. STAT-1α associates with TNFR1 in TNF-α-treated cells, and this association attenuates TNF-α-mediated NF-κB activation. We hypothesized that nuclear localization of STAT-1α due to IFN-γ signaling would preclude it from being recruited to the TNFR1 and therefore enhance TNF-α-induced NF-κB activation. In the RAW264.7 macrophage cell line, TNF-α treatment indeed recruits STAT-1α to the TNFR1, and this association is abrogated when cells are exposed to IFN-γ. TNF-α treatment induces a more robust activation of NF-κB in STAT-1α-deficient cells, and restoration of STAT-1α inhibits TNF-α-dependent NF-κB activation. Our results suggest that a receptor-proximal level of cross-talk exists between these two cytokine pathways: IFN-γ limits STAT-1α availability to the TNFR1 by depleting STAT-1α from the cytoplasm, thus allowing for optimal NF-κB activation upon TNF-α ligation.
  • Published In

    Digital Object Identifier (doi)

    Author List

  • Wesemann DR; Benveniste EN
  • Start Page

  • 5313
  • End Page

  • 5319
  • Volume

  • 171
  • Issue

  • 10