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Cell Biol Int. 2000;24(3):163-74.

Annexin I is stored within gelatinase granules of human neutrophil and mobilized on the cell surface upon adhesion but not phagocytosis.

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  • 1Department of Biochemical Pharmacology, The William Harvey Research Institute, St. Bartholomew's and The Royal London School of Medicine and Dentistry, Charterhouse Square, London, UK. m.perretti@qmw.ac.uk

Abstract

Annexin I, a member of the calcium- and phospholipid-binding annexin superfamily of proteins, is largely present in human neutrophils. To determine its exact intracellular distribution a combination of flow cytometry, confocal microscopy and electron microscopy analyses were performed on resting human neutrophils as well as on cells which had been activated. In resting neutrophils, annexin I was found to be present in small amounts in the nucleus, in the cytoplasm and partially also associated with the plasma membrane. The cytoplasmic pool of annexin I was predominant, and the protein was co-localized with gelatinase (marker of gelatinase granules), but not with human serum albumin or CD35 (markers of secretory vesicles), or with lysosomes. Electron microscopy showed the presence of annexin I inside the gelatinase granules. Neutrophil adhesion to monolayers of endothelial cells, but not phagocytosis of particles of opsonized zymosan, provoked an intense mobilization of annexin I, with a marked externalization on the outer leaflet of the plasma membrane. Remaining intracellular annexin I was also found in proximity of the plasma membrane. These results provide a novel mechanism for annexin I secretion from human neutrophils, which is via a degranulation event involving gelatinase granules.

Copyright 2000 Academic Press.

PMID:
10772777
[PubMed - indexed for MEDLINE]
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