Noncanonical IRF3 function mediates STING-dependent pro-inflammatory cytokine production in macrophages

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• STING (STimulator of INterferon Genes) is crucial for innate immunity, mediating host defense via interferon and cytokine production.
• While STING's role in interferon production is well-understood, its mechanisms for inducing pro-inflammatory cytokines are less clear.

Purpose of the Study:

• To elucidate the mechanisms underlying STING-mediated pro-inflammatory cytokine production.
• To investigate the role of IRF3 in STING signaling pathways.

Main Methods:

• Macrophage-based assays to assess inflammatory cytokine production.
• Genetic manipulation to study the function of IRF3.
• Analysis of transcription factor activation (NF-κB, AP-1).

Main Results:

• IRF3 is essential for STING-induced inflammatory cytokine production in macrophages.
• IRF3 deficiency impairs STING responses without affecting NF-κB activation, but impacts the AP-1 complex.
• IRF3's function in this context is independent of its phosphorylation and its canonical role in Type I interferon induction.

Conclusions:

• IRF3 possesses a noncanonical function critical for STING-mediated pro-inflammatory cytokine production.
• This function relies on IRF3 recruitment to a specific motif on STING.
• Findings uncover a new layer of regulation in innate immune responses mediated by STING and IRF3.