| Interferon regulatory factors (IRFs) comprise a family of transcription factors that function within the Jak/Stat pathway to regulate interferon (IFN) and IFN-inducible gene expression in response to viral infection (1). IRFs play an important role in pathogen defense, autoimmunity, lymphocyte development, cell growth, and susceptibility to transformation. The IRF family includes nine members: IRF-1, IRF-2, ISGF3γ/p48, IRF-3, IRF-4 (Pip/LSIRF/ICSAT), IRF-5, IRF-6, IRF-7, and IRF-8/ICSBP. All IRF proteins share homology in their amino-terminal DNA-binding domains. IRF family members regulate transcription through interactions with proteins that share similar DNA-binding motifs, such as IFN-stimulated response elements (ISRE), IFN consensus sequences (ICS), and IFN regulatory elements (IRF-E) (2).IRF-5 is expressed in lymphoid tissues and peripheral blood lymphocytes and participates in the induction of type I interferon genes following viral infection (3). Activation of IRF-5 signaling is triggered by components of the toll-like receptor (TLR) pathway, including TLR7 and MyD88 (4,5). Genetic variants of IRF-5 have been associated with disorders where the IFN pathway is abnormally activated, such as systemic lupus erythematosus (6,7). |
