Glues that can STING: Lipids in innate immunity

Area of Science:

• Cellular Biology
• Immunology
• Lipid Biochemistry

Background:

• Phosphoinositides are critical regulators of cellular signaling pathways.
• The STING (STimulator of INterferon Genes) pathway is a key component of the innate immune system.
• Understanding the molecular mechanisms that control STING activation is essential for developing new immunotherapies.

Purpose of the Study:

• To identify the specific lipids that regulate STING oligomerization and immune signaling.
• To elucidate the role of phosphoinositides and cholesterol in STING activation.
• To explain the necessity of STING trafficking for initiating immune responses.

Main Methods:

• Lipidomics analysis
• Protein-lipid interaction assays
• Cellular imaging techniques
• Biochemical assays to measure TBK1 activation

Main Results:

• Phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P₂) and cholesterol were identified as key lipids.
• These lipids stabilize STING oligomers, promoting the formation of active signaling complexes.
• STING trafficking from the endoplasmic reticulum (ER) to the Golgi is required for PtdIns(3,5)P₂ and cholesterol-dependent TBK1 activation.

Conclusions:

• PtdIns(3,5)P₂ and cholesterol are essential co-factors for STING-mediated immune signaling.
• The localization of STING to the Golgi is critical for its interaction with these lipids and subsequent activation.
• This work provides a molecular explanation for the trafficking requirements of STING activation.