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Two independently regulated secretory pathways in mast cells
J Kirillova1, P Thomas, W Almers
1Department of Physiology and Biophysics, University of Washington, Seattle 98195.
Journal of Physiology, Paris
|January 1, 1993
Summary
Mast cells release small vesicles via calcium-triggered exocytosis, similar to hormone secretion in neuroendocrine cells. This suggests a shared secretory pathway is active in both cell types.
Area of Science:
- Cell Biology
- Immunology
- Neuroendocrinology
Background:
- Mast cells are known to secrete various substances.
- The precise mechanisms and pathways for mast cell vesicle secretion are not fully elucidated.
- Evidence suggests mast cells release both large and small vesicles independently.
Purpose of the Study:
- To investigate the mechanism of small vesicle release from mast cells.
- To determine if calcium triggers the exocytosis of small vesicles in mast cells.
- To compare the secretory pathway of mast cells with that of neuroendocrine cells.
Main Methods:
- Utilized patch-clamp capacitance measurements to monitor vesicle fusion events.
- Employed flash photolysis of caged calcium to rapidly increase intracellular calcium concentration.
- Combined electrophysiological recordings with calcium uncaging to study exocytosis kinetics.
Main Results:
- Demonstrated that calcium influx triggers the exocytosis of small vesicles from mast cells.
- Showed that the kinetics of this calcium-triggered exocytosis are identical to those observed for dense-core peptidergic vesicle release in pituitary melanotrophs.
- Identified a shared secretory pathway between mast cells and neuroendocrine cells.
Conclusions:
- The secretory pathway for hormone release in neuroendocrine cells is also active in mast cells and eosinophils.
- Calcium acts as a key trigger for the exocytosis of small vesicles in mast cells.
- The identity of the secreted mediator via this pathway in mast cells remains unknown.