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Compound versus multigranular exocytosis in peritoneal mast cells
G Alvarez de Toledo1, J M Fernandez
1Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104-6085.
The Journal of General Physiology
|March 1, 1990
Summary
Large fusion events during mast cell degranulation are caused by pre-existing peripheral granule aggregates, not single granule fusions. This finding reveals a novel mechanism for potentiating secretory responses.
Area of Science:
- Cell Biology
- Membrane Biology
- Immunology
Background:
- Mast cells release secretory granules via exocytosis.
- Membrane capacitance measurements reflect membrane area changes during degranulation.
Purpose of the Study:
- To investigate the origin of large membrane fusion events during mast cell degranulation.
- To determine if granule-to-granule fusion precedes exocytosis.
Main Methods:
- Whole-cell patch-pipette technique to measure membrane capacitance.
- Mathematical modeling of mast cell degranulation.
Main Results:
- Large fusion events contribute up to 30% of membrane expansion.
- These events occur primarily during the initial degranulation phase.
- Results support exocytosis of pre-formed peripheral granule aggregates.
Conclusions:
- Large fusion events result from the exocytosis of pre-existing peripheral granule aggregates.
- A novel mechanism involving sequential fusion of 'flickering' granules forms these aggregates.
- Peripheral granule aggregation may enhance subsequent secretory responses.