Members of the interferon regulatory transcription factor (IRF) family are involved in antiviral defense, cell growth regulation, and immune activation.  Initially identified as regulators of type I interferon (IFN) gene induction, IRF family of transcription factors transduce signals for multiple classes of the pattern-recognition receptors (PRRs), such as Toll-like receptors, retinoic acid–inducible gene-I (RIG-I)-like receptors (RLRs), NOD-like receptors (NLRs), C-type lectin receptors (CLRs), and other nucleic acid–sensing receptors.  When activated, each IRF protein translocates to the nucleus and binds to DNA sequence similar to IFN-stimulated response element (ISRE).  IRF activation can enhance the IFN-mediated antiviral immune response.  Oppositely, abnormal activation of type I IFNs contributes to the development of autoimmune diseases, such as SLE.  Signosis has established an IRF luciferase reporter stable cell line that can be used as a reporter system for monitoring the activation of IRF triggered by stimuli treatment, enforced gene expression and gene knockdown.

​

The cell line is established by transfection using a pTA-GAS/ISRE-luciferase reporter vector, which contains IRF binding sites, a minimal promoter upstream of the firefly luciferase coding region, along with hygromycin expression vector followed by hygromycin selection.  The hygromycin resistant clones were subsequently screened for IFNgamma-induced luciferase activity.