Enlargeosome, an Exocytic Vesicle Resistant to Nonionic Detergents, Undergoes Endocytosis via a Nonacidic Route

Ions 0301 basic medicine Photolysis Ionomycin Detergents Membrane Proteins Endosomes Intracellular Membranes Hydrogen-Ion Concentration Electric Capacitance Endocytosis Exocytosis Cell Line Neoplasm Proteins Rats Kinetics Microscopy, Electron 03 medical and health sciences Cholesterol Animals Humans Calcium
DOI: 10.1091/mbc.e04-07-0577 Publication Date: 2004-10-07T00:14:05Z
ABSTRACT
Enlargeosomes, a new type of widely expressed cytoplasmic vesicles, undergo tetanus toxin-insensitive exocytosis in response to cytosolic Ca2+concentration ([Ca2+]i) rises. Cell biology of enlargeosomes is still largely unknown. By combining immunocytochemistry (marker desmoyokin-Ahnak, d/A) to capacitance electrophysiology in the enlargeosome-rich, neurosecretion-defective clone PC12-27, we show that 1) the two responses, cell surface enlargement and d/A surface appearance, occur with similar kinetics and in the same low micromolar [Ca2+]irange, no matter whether induced by photolysis of the caged Ca2+compound o-nitrophenyl EGTA or by the Ca2+ionophore ionomycin. Thus, enlargeosomes seem to account, at least in large part, for the exocytic processes triggered by the two stimulations. 2. The enlargeosome membranes are resistant to nonionic detergents but distinct from other resistant membranes, rich in caveolin, Thy1, and/or flotillin1. 3. Cell cholesterol depletion, which affects many membrane fusions, neither disrupts enlargeosomes nor affects their regulated exocytosis. 4. The postexocytic cell surface decline is [Ca2+]idependent. 5. Exocytized d/A-rich membranes are endocytized and trafficked along an intracellular pathway by nonacidic organelles, distinct from classical endosomes and lysosomes. Our data define specific aspects of enlargeosomes and suggest their participation, in addition to cell differentiation and repair, for which evidence already exists, to other physiological and pathological processes.
SUPPLEMENTAL MATERIAL
Coming soon ....
REFERENCES (50)
CITATIONS (44)
EXTERNAL LINKS
PlumX Metrics
RECOMMENDATIONS
FAIR ASSESSMENT
Coming soon ....
JUPYTER LAB
Coming soon ....