DOK3 negatively regulates LPS responses and endotoxin tolerance

Area of Science:

• Immunology
• Molecular Biology

Background:

• Innate immune activation via Toll-like receptors (TLRs) is essential for host defense but requires strict regulation to prevent detrimental sustained cell activation.
• Repeated exposure to lipopolysaccharide (LPS) induces endotoxin tolerance, rendering cells hypo-responsive to further TLR stimulation.

Purpose of the Study:

• To investigate the role of DOK3 as a negative regulator of Toll-like receptor (TLR) signaling.
• To elucidate the mechanisms by which DOK3 influences lipopolysaccharide (LPS)-induced responses and endotoxin tolerance.

Main Methods:

• Macrophage stimulation with LPS.
• Analysis of ERK activation and cytokine production.
• Investigation of DOK3 ubiquitination and degradation pathways.
• Assessment of DOK3 expression in endotoxin tolerance.
• Phenotyping of DOK3-deficient mice.

Main Results:

• DOK3 limits LPS-induced ERK activation and cytokine responses in macrophages.
• LPS triggers ubiquitin-mediated degradation of DOK3, leading to SOS1 degradation and inhibited ERK activation.
• DOK3-deficient mice exhibit hypersensitivity to LPS and altered in vivo cytokine profiles.
• During endotoxin tolerance, stable DOK3 expression negatively regulates SHIP1, IRAK-M, SOCS1, and SOS1.
• DOK3-deficient macrophages display heightened sensitivity to LPS-induced tolerance.

Conclusions:

• DOK3 acts as a crucial negative regulator of TLR signaling, impacting both naive and endotoxin-tolerant states.
• The absence of DOK3 potentiates LPS signaling and contributes to the development of endotoxin tolerance.
• DOK3 plays a significant role in modulating immune responses to LPS.