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Microfilament-associated, local degranulation of rat peritoneal mast cells
1Department of Pharmacology, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Abstract:
When compound 48/80 was applied by means of microelectrophoresis to the surface of a rat peritoneal mast cell, localized degranulation was observed in the area close to the microelectrode tip. The extruded granules were connected to the cell surface by filaments. The filaments were elongated radially and, in some occasions, projected to a length of 5 microns. A few minutes later, the length of the protruded filaments became shorter and shorter and, finally, the extruded granules were reincorporated into the cell. When rhodamine-phalloidin, an F-actin-specific dye, was perfused the extruded granules and filaments were stained by this dye. This indicates that actin filaments or fragments of them exist on the granule surface and on the cell surface at the site of degranulation. These actin filaments bound to the mast cell granules may play an important role, not only for the extrusion of the granules, but also for the reuptake of extruded granules into the cytoplasm.
Insights
Compound 48/80 triggers localized degranulation in rat mast cells, extruding granules via actin filaments. These filaments facilitate both granule extrusion and subsequent reuptake into the cell.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Mast cells are key immune cells involved in allergic responses.
- Compound 48/80 is a known mast cell degranulator.
- Understanding mast cell degranulation mechanisms is crucial for allergy and inflammation research.
Purpose of the Study:
- To investigate the role of actin filaments in mast cell degranulation induced by compound 48/80.
- To elucidate the mechanism of granule extrusion and reuptake in rat peritoneal mast cells.
Main Methods:
- Microelectrophoresis of compound 48/80 onto rat peritoneal mast cells.
- Fluorescence microscopy using rhodamine-phalloidin, an F-actin-specific dye.
Main Results:
- Localized degranulation and granule extrusion connected by filaments were observed.
- Filaments extended radially up to 5 microns from the cell surface.
- Extruded granules were eventually reincorporated into the mast cell.
- Rhodamine-phalloidin staining indicated the presence of actin filaments on extruded granules and the cell surface at the degranulation site.
Conclusions:
- Actin filaments are involved in the extrusion of mast cell granules induced by compound 48/80.
- These actin filaments likely play a role in both the release and subsequent reuptake of granules.
- The findings provide new insights into the dynamic process of mast cell degranulation and granule trafficking.