IRF8 and IRF3 cooperatively regulate rapid interferon-β induction in human blood monocytes

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• Robust and rapid induction of interferon-beta (IFN-β) in monocytes is crucial for innate immunity.
• This rapid IFN-β production is a unique characteristic of human blood monocytes.

Purpose of the Study:

• To elucidate the molecular mechanism behind rapid IFN-β induction in human monocytes.
• To identify the key transcription factors and their interactions involved in this process.

Main Methods:

• Investigated the role of transcription factors IRF8 and IRF3 in IFN-β production using knockdown and reintroduction experiments.
• Analyzed the binding of IRF8 and PU.1 to the IFN-β promoter in vivo.
• Mapped protein-protein interaction regions between IRF8 and IRF3.

Main Results:

• IRF8 is essential for rapid IFN-β transcription in monocytes; its knockdown abrogated production.
• IRF8 binds constitutively to the IFN-β promoter with PU.1.
• IRF3 was identified as a novel interaction partner of IRF8, crucial for IFN-β induction.

Conclusions:

• A model is proposed where IRF8 and PU.1 form a scaffold on the IFN-β promoter.
• This scaffold facilitates IRF3 recruitment, enabling rapid IFN-β transcription.
• This mechanism explains the monocyte-specific rapid IFN-β response.