Enhanced Membrane Fluidization and Cholesterol Displacement by 1-Heptanol Inhibit Mast Cell Effector Functions

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• High-affinity IgE receptor (FcεRI) signaling relies on membrane compartmentalization.
• 1-heptanol is a known cell membrane fluidizer, altering membrane properties.

Purpose of the Study:

• To investigate the functional consequences of 1-heptanol-induced membrane changes on mast cell signaling.
• To determine how membrane fluidization affects FcεRI signaling pathways and mast cell effector functions.

Main Methods:

• Mast cells were treated with 1-heptanol.
• FcεRI lateral mobility, internalization, and phosphorylation were assessed.
• Signaling pathway components (SYK/LAT1/PLCγ1, SAPK/JNK) were analyzed.
• Effector functions (calcium response, degranulation, cytokine production, ROS production) were measured.
• Heat shock protein 70 expression and STIM1-ORAI1 coupling were evaluated using flow-FRET.

Main Results:

• 1-heptanol reduced membrane thermal stability and increased FcεRI lateral mobility.
• Initial FcεRI-β and SYK/LAT1/PLCγ1 pathway phosphorylation remained unaffected.
• 1-heptanol inhibited SAPK/JNK phosphorylation, calcium response, degranulation, and cytokine production.
• Membrane hyperfluidization induced a heat shock-like response and impaired STIM1-ORAI1 coupling.
• Antigen-induced reactive oxygen species production was inhibited, and plasma membrane permeability was potentiated.

Conclusions:

• 1-heptanol-induced membrane fluidization dysregulates mast cell signaling at multiple levels.
• It inhibits FcεRI internalization and downstream effector functions without affecting initial FcεRI phosphorylation.
• The findings highlight the critical role of membrane properties in FcεRI-mediated mast cell activation.