Interferon regulatory factor 9 (IRF9)

Interferon regulatory factor 9 (IRF9) is a member of the IRF transcription factor family that regulates immune responses, particularly antiviral signaling. IRF9, also known as ISGF3γ or p48, acts as an essential component of the interferon-stimulated gene factor 3 (ISGF3) complex, partnering with STAT1 and STAT2 to bind promoter elements on interferon-stimulated genes (ISGs). Upon type I interferon stimulation, IRF9 forms a complex with STAT1 and STAT2, translocates to the nucleus, and initiates transcription of ISGs, mediating the cellular antiviral state. Beyond viral defense, IRF9 has roles in cell proliferation, inflammation, tumorigenesis, cardiovascular disease, and autoimmune regulation. Its function is regulated at the protein level mostly through interactions (especially with STAT2) and post-translational modifications (e.g., acetylation, phosphorylation). IRF9 also interacts with key metabolic regulators such as PPARα and SIRT1, influencing disease outcomes. Aberrant IRF9 activity is implicated in several disease states, including cancer and cardiovascular injury[1][3]. No drugs currently target IRF9 directly, but its activity is modulated within the broader interferon/JAK-STAT pathway.

Other names

ISGF3GIRF-9ISGF-3 gammaISGF3 p48 subunitInterferon-stimulated gene factor 3 gammaTranscriptional regulator ISGF3 subunit gammaIFN-alpha-responsive transcription factor subunitp48ISGF3interferon-stimulated transcription factor 3, gamma (48kD)

Drugs do not directly target IRF9, but activation and repression of the IRF9/ISGF3 complex is regulated by JAK/STAT pathway modulators, including interferons[1][2].