IRF family of transcription factors as regulators of host defense

Interferon regulatory factors (IRFs) constitute a family of transcription f actors that commonly possess a novel helix-turn-helix DNA-binding motif. Fo llowing the initial identification of two structurally related members, IRF -1 and IRF-2, seven additional members have now been reported. In addition, virally encoded IRFs, which may interfere with cellular IRFs, have also be en identified. Thus far, intensive functional analyses have been done on IR F-1, revealing a remarkable functional diversity of this transcription fact or in the regulation of cellular response in host defense. Indeed, IRF-1 se lectively modulates different sets of genes, depending on the cell type and /or the nature of cellular stimuli, in order to evoke appropriate responses in each. More recently, much attention has also been focused on other IRF family members. Their functional roles, through interactions with their own or other members of the family of transcription factors, are becoming clea rer in the regulation of host defense, such as innate and adaptive immune r esponses and oncogenesis.