Release of secretory products during transient vesicle fusion

Toledo, G. Álvarez de; Fernández‐Chacón, Rafael; Fernández, Julio M.

doi:10.1038/363554a0

Cited by 554 publications

(151 citation statements)

References 17 publications

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“…The simultaneous capacitance measurement shows that the foot developed immediately after fusion began. These results are similar to those reported in mast cells, where the foot was shown to be due to (i) the fusion pore that forms between secretory vesicles and the plasma membrane and (ii) the manner in which the vesicle's contents are released from a polymer gel matrix that fills the inside of the secretory vesicle (23)(24)(25). Similar vesicular association has been inferred in release studies from chromaffin cells (26,27).…”

Section: Resultssupporting

confidence: 80%

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Colocalization of calcium entry and exocytotic release sites in adrenal chromaffin cells.

Robinson

Finnegan

Monck

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

130

106

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ABSTRACT"Snapshot" images of localized Ca2+ influx into patch-clamped chromaffin cells were captured by using a recently developed pulsed-laser imaging system. Transient opening of voltage-sensitive Ca2+ channels gave rise to localized elevations of Ca2+ that had the appearance of either "hotspots" or 8 ,uM 5-fluoro-2'-deoxyuridine, gentamicin at 50 ,ug/ml, 10 ,uM cytosine arabinofuranoside, Fungizone at 2.5 ,ug/ml, penicillin at 25 units/ml, and streptomycin at 25 jig/ml and plated at a density of 100,000 cells per ml on glass coverslips in 35-mm-diameter Petri dishes. Cells were cultured in a humidified atmosphere at 37°C in the presence of 5% CO2 for 1-5 days prior to use. For experiments, cells were washed in an extracellular medium comprising 120 mM NaCl, 20 mM Hepes, 4 mM MgCl2, 2 mM CaCl2, 0.4% glucose, and 1 ,M tetrodotoxin at pH 7.2 (adjusted with NaOH). The patch-pipette solution contained 120 mM cesium D-glutamate, 30 mM Hepes, 8 mM NaCl, 1 mM MgCl2, 2 mM ATP, and 0.3 mM GTP at pH 7.2, with either 100 ,tM EGTA or, for imaging studies, 0.4 mM rhod-2 (triammonium salt). Experiments were carried out at room temperature.

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Section: Resultssupporting

confidence: 80%

“…In Fig. lb, a foot can be seen that precedes the main spike (22,23); in contrast, there is no observable foot in the event seen in Fig. lc.…”

Section: Resultsmentioning

confidence: 94%

Colocalization of calcium entry and exocytotic release sites in adrenal chromaffin cells.

Robinson

Finnegan

Monck

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

130

106

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“…3B). In previous studies, this method has been used to detect exocytosis from adrenal chromaffin cells, PC-12 cells, mast cells, and individual pancreatic ␤ cells (23,(30)(31)(32)(33)(34). The anodic current resulting from a secreted substance appears as a series of spikes that indicate concentration pulses occurring at the electrode surface.…”

Section: Resultsmentioning

confidence: 99%

Insulin-like growth factor II signaling through the insulin-like growth factor II/mannose-6-phosphate receptor promotes exocytosis in insulin-secreting cells

Zhang

Tally

Larsson

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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The insulin-like growth factor II (IGF-II)͞ mannose-6-phosphate (M-6-P) receptor is known to participate in endocytosis as well as sorting of lysosomal enzymes and is involved in membrane trafficking through rapid cycling between cytosolic membrane compartments and the plasma membrane. Here we demonstrate that IGF-II, acting through the IGF-II͞M-6-P receptor, promotes exocytosis of insulin in the pancreatic ␤ cell. The effect of IGF-II was evoked at nonstimulatory concentrations of glucose, was mediated by a pertussis toxin sensitive GTP-binding protein, was dependent on protein kinase C-induced phosphorylation, and was independent of changes in cytoplasmic free Ca 2؉ concentration. Since the applied concentration of IGF-II is within the range normally found free in circulation in humans, this novel signaling pathway for the IGF-II͞M-6-P receptor is likely to be involved in modulation of insulin exocytosis under physiological conditions.

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“…Interestingly, patch clamp experiments suggest that serotonin is preferentially released from the vesicular halo in mast cell vesicles in modes of release where only part of the vesicle cargo has been released. 44 Examining the concentrations of catecholamine across these compartments in our system and comparing to the spatial distribution, when treated for hours with L-DOPA, suggest that the thermodynamics to translocate these amines across the nanometer dense core is extremely large. …”

mentioning

confidence: 93%

Nano Secondary Ion Mass Spectrometry Imaging of Dopamine Distribution Across Nanometer Vesicles

et al. 2016

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We report an approach to spatially resolve the content across nanometer neuroendocrine vesicles in nerve-like cells by correlating super high-resolution mass spectrometry imaging, NanoSIMS, with transmission electron microscopy (TEM). Furthermore, intracellular electrochemical cytometry at nanotip electrodes is used to count the number of molecules in individual vesicles to compare to imaged amounts in vesicles. Correlation between the NanoSIMS and TEM provides nanometer resolution of the inner structure of these organelles. Moreover, correlation with electrochemical methods provides a means to quantify and relate vesicle neurotransmitter content and release, which is used to explain the slow transfer of dopamine between vesicular compartments. These nanoanalytical tools reveal that dopamine loading/unloading between vesicular compartments, dense core and halo solution, is a kinetically limited process. The combination of NanoSIMS and TEM has been used to show the distribution profile of newly synthesized dopamine across individual vesicles. Our findings suggest that the vesicle inner morphology might regulate the neurotransmitter release event during open and closed exocytosis from dense core vesicles with hours of equilibrium needed to move significant amounts of catecholamine from the protein dense core despite its nanometer size. KEYWORDS: nanoimaging, NanoSIMS, vesicle content, electrochemistry, nanocompartments C hemical communication in eukaryotic cells relies heavily on loading and trafficking of secretory vesicles to the plasma membrane. Upon stimulation, the loaded, docked secretory vesicles fuse with the plasma membrane and discharge their neurotransmitter cargo into the extracellular space. This process, called exocytosis, is fundamental and highly regulated. 1,2 Regulation of exocytosis has been widely studied, and the understanding of its mechanism is still under debate. Several mechanisms have been reported such as all-or-nothing release during which vesicles completely fuse with the plasma membrane and release their total content. 3 Contrary to the all-or-nothing mode, partial release mechanisms have been proposed, suggesting the transient opening of the fusion pore between the cell membrane and secretory vesicle followed by closing again. 4 In addition to the release event, exocytosis is also regulated through vesicle loading. In general, this process involves a neurotransmitter transporter, an integral vesicle membrane protein that uses the pH gradient across the vesicle membrane, to drive uptake of neurotransmitters into the vesicle. 5−8 Defining the vesicle storage mechanisms would be an important piece of the exocytosis regulation puzzle. 5,9,10 Several cell types have been employed for loading studies among which neuroendocrine cells have had an important role as a model system. They possess two types of secretory vesicles, synaptic-like microvesicles (SLMVs) and so-called large densecore vesicles (LDCVs). The larger LDCVs typically have diameters around 150−300 nm and an inner ...

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Release of secretory products during transient vesicle fusion

Cited by 554 publications

References 17 publications

Colocalization of calcium entry and exocytotic release sites in adrenal chromaffin cells.

Colocalization of calcium entry and exocytotic release sites in adrenal chromaffin cells.

Insulin-like growth factor II signaling through the insulin-like growth factor II/mannose-6-phosphate receptor promotes exocytosis in insulin-secreting cells

Nano Secondary Ion Mass Spectrometry Imaging of Dopamine Distribution Across Nanometer Vesicles

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