title: The type I interferon signaling pathway is a target for glucocorticoid inhibition.
abstract: Type I interferon (IFN) is essential for host defenses against viruses; however, dysregulated IFN signaling is causally linked to autoimmunity, particularly systemic lupus erythematosus. Autoimmune disease treatments rely on glucocorticoids (GCs), which act via the GC receptor (GR) to repress proinflammatory cytokine gene transcription. Conversely, cytokine signaling through cognate Jak/STAT pathways is reportedly unaffected or even stimulated by GR. Unexpectedly, we found that GR dramatically inhibited IFN-stimulated gene (ISG) expression in macrophages. The target of inhibition, the heterotrimeric STAT1-STAT2-IRF9 (ISGF3) transcription complex, utilized the GR cofactor GRIP1/TIF2 as a coactivator. Consequently, GRIP1 knockdown, genetic ablation, or depletion by GC-activated GR attenuated ISGF3 promoter occupancy, preinitiation complex assembly, and ISG expression. Furthermore, this regulatory loop was restricted to cell types such as macrophages expressing the GRIP1 protein at extremely low levels, and pharmacological disruption of the GR-GRIP1 interaction or transient introduction of GRIP1 restored RNA polymerase recruitment to target ISGs and the subsequent IFN response. Thus, type I IFN is a cytokine uniquely controlled by GR at the levels of not only production but also signaling through antagonism with the ISGF3 effector function, revealing a novel facet of the immunosuppressive properties of GCs.
authors.affiliation: Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, 1300 York Avenue, New York, New York 10021, USA.
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Flammer
authors.forename: Jana
authors.initials: J
authors.lastname: Dobrovolna
authors.forename: Megan A
authors.initials: MA
authors.lastname: Kennedy
authors.forename: Yurii
authors.initials: Y
authors.lastname: Chinenov
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Glass
authors.forename: Lionel B
authors.initials: LB
authors.lastname: Ivashkiv
authors.forename: Inez
authors.initials: I
authors.lastname: Rogatsky
mesh_terms: D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D007370:Interferon Type I / Q000494:pharmacology*; D050833:Interferon-Stimulated Gene Factor 3, alpha Subunit / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D005938:Glucocorticoids; C491309:Grip1 protein, mouse; D007370:Interferon Type I; D050833:Interferon-Stimulated Gene Factor 3, alpha Subunit; D009419:Nerve Tissue Proteins; D003907:Dexamethasone