NF-κB signaling dynamics is controlled by a dose-sensing autoregulatory loop

Area of Science:

• Immunology
• Cell Signaling
• Molecular Biology

Background:

• Signaling protein dynamics (oscillatory, transient, sustained) influence gene expression and cell fate.
• Molecular mechanisms for stimulus- and dose-dependent signaling dynamics are poorly understood.
• Innate immune signaling networks encode crucial information through dynamic patterns.

Purpose of the Study:

• To dissect mechanisms of stimulus- and dose-encoding in innate immune signaling.
• To identify molecular players responsible for dynamic signal regulation.
• To understand how signaling dynamics shape cellular responses.

Main Methods:

• Single-cell analysis of innate immune signaling pathways.
• Perturbation of signaling networks using inducible gene expression and optogenetics.
• Investigation of Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) signaling dynamics.

Main Results:

• Identified a dose-dependent, autoinhibitory loop in TLR and IL-1R signaling.
• Discovered that IL-1R-associated kinase 1 (IRAK1) acts as the dose-sensing node.
• IRAK1 regulates signal flow and inhibits NF-κB nucleocytoplasmic oscillations, independent of its kinase activity.

Conclusions:

• IRAK1 is essential for dose-dependent innate immune signaling, controlling signal refractoriness.
• Protein functions not obvious from network topology (like IRAK1's non-kinase role) are critical for dynamic responses.
• Understanding these mechanisms is key to deciphering how cells interpret external stimuli.