NUCLEIC ACIDS, PROTEIN SYNTHESIS, AND MOLECULAR GENETICS
Synergy between Interferon-γ and Tumor Necrosis Factor-α in Transcriptional Activation Is Mediated by Cooperation between Signal Transducer and Activator of Transcription 1 and Nuclear Factor κB*

https://doi.org/10.1074/jbc.272.23.14899Get rights and content
Under a Creative Commons license
open access

Interferon-γ (IFNγ) and tumor necrosis factor-α (TNFα) cooperate to induce the expression of many gene products during inflammation. The present report demonstrates that a portion of this cooperativity is mediated by synergism between two distinct transcription factors: signal transducer and activator of transcription 1 (STAT1) and nuclear factor κB (NF-κB). IFNγ and TNFα synergistically induce expression of mRNAs encoding interferon regulatory factor-1 (IRF-1), intercellular adhesion molecule-1, Mig (monokine induced by γ-interferon), and RANTES (regulated on activation normalTcell expressed andsecreted) in normal but not STAT1-deficient mouse fibroblasts, indicating a requirement for STAT1. Transient transfection assays in fibroblasts using site-directed mutants of a 1.3-kilobase pair sequence of the IRF-1 gene promoter revealed that the synergy was dependent upon two sequence elements; a STAT binding element and a κB motif. Artificial constructs containing a single copy of both a STAT binding element and a κB motif linked to the herpes virus thymidine kinase promoter were able to mediate synergistic response to IFNγ and TNFα; such response varied with both the relative spacing and the specific sequence of the regions between these two sites. Cooperatively responsive sequence constructs bound both STAT1α and NF-κB in nuclear extracts prepared from IFNγ- and/or TNFα-stimulated fibroblasts, although binding of individual factors was not cooperative. Thus, the frequently observed synergy between IFNγ and TNFα in promoting inflammatory response depends in part upon cooperation between STAT1α and NF-κB, which is most likely mediated by their independent interaction with one or more components of the basal transcription complex.

Cited by (0)

*

This work was supported by U. S. Public Health Service Grant CA62220. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1

The abbreviations used are:

    IFN

    interferon

    TNF

    tumor necrosis factor

    STAT

    signal transducer and activator of transcription

    SBE

    STAT binding element

    IRF-1

    interferon regulatory factor-1

    ICAM-1

    intercellular adhesion molecule-1

    PCR

    polymerase chain reaction

    IP-10

    IFN-inducible protein

    10 kDa

    kb, kilobase pair

    NF-κB

    nuclear factor κB

    TK

    thymidine kinase

    CAT

    chloramphenicol acetyltransferase

    EMSA

    electrophoretic mobility shift assay