PMID: 29626214
Hudson WH, Vera IMS, Nwachukwu JC, Weikum ER, Herbst AG, Yang Q, Bain DL, Nettles KW, Kojetin DJ, Ortlund EA
Cryptic glucocorticoid receptor-binding sites pervade genomic NF-kappaB response elements.
Nat Commun. 2018 Apr 6;9(1):1337. doi: 10.1038/s41467-018-03780-1.
Glucocorticoids (GCs) are potent repressors of NF-kappaB activity, making them a preferred choice for treatment of inflammation-driven conditions. Despite the widespread use of GCs in the clinic, current models are inadequate to explain the role of the glucocorticoid receptor (GR) within this critical signaling pathway. GR binding directly to NF-kappaB itself-tethering in a DNA binding-independent manner-represents the standing model of how GCs inhibit NF-kappaB-driven transcription. We demonstrate that direct binding of GR to genomic NF-kappaB response elements (kappaBREs) mediates GR-driven repression of inflammatory gene expression. We report five crystal structures and solution NMR data of GR DBD-kappaBRE complexes, which reveal that GR recognizes a cryptic response element between the binding footprints of NF-kappaB subunits within kappaBREs. These cryptic sequences exhibit high sequence and functional conservation, suggesting that GR binding to kappaBREs is an evolutionarily conserved mechanism of controlling the inflammatory response.