Functional and spatial segregation of secretory vesicle pools according to vesicle age

Duncan, Rory R.; Greaves, Jennifer; Wiegand, Ulrich K.; Matskevich, Ioulia; Bodammer, G.; Apps, David K.; Shipston, Michael J.; Chow, Robert H.

doi:10.1038/nature01389

Cited by 198 publications

(201 citation statements)

References 25 publications

Supporting

Mentioning

178

Contrasting

Unclassified

Order By: Relevance

“…Under the intense stimulation conditions used here, recruitment for secretion is likely to bypass subtle differences in fusogenicity that may dominate under more physiological conditions; therefore, it is possible that the release of a broad spectrum of vesicles is induced with the intense stimulation used here. An entirely different explanation is that the cells have two separate populations of vesicles, as has been proposed for chromaffin cells (19,33) and PC12 cells (50). It is possible that AP-3 promotes the formation of smaller vesicles because overexpression of AP-3 increases the frequency of small events.…”

Section: Vesicle Size Is Altered In a Manner That Mirrors Quantal Sizmentioning

confidence: 87%

See 1 more Smart Citation

Regulation of large dense-core vesicle volume and neurotransmitter content mediated by adaptor protein 3

Grabner

Price

Lysakowski

et al. 2006

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

View full text Add to dashboard Cite

Adaptor protein 3 (AP-3) is a vesicle-coat protein that forms a heterotetrameric complex. Two types of AP-3 subunits are found in mammalian cells. Ubiquitous AP-3 subunits are expressed in all tissues of the body, including the brain. In addition, there are neuronal AP-3 subunits that are thought to serve neuron-specific functions such as neurotransmitter release. In this study, we show that overexpression of neuronal AP-3 in mouse chromaffin cells results in a striking decrease in the neurotransmitter content of individual vesicles (quantal size), whereas deletion of all AP-3 produces a dramatic increase in quantal size; these changes were correlated with alterations in dense-core vesicle size. AP-3 appears to localize in the trans-Golgi network and possibly immature secretory vesicles, where it may be involved in the formation of neurosecretory vesicles.amperometry ͉ electron microscopy ͉ quantal content ͉ vesicle size ͉ chromaffin cells

show abstract

Section: Vesicle Size Is Altered In a Manner That Mirrors Quantal Sizmentioning

confidence: 87%

“…Maturation of these vesicles, which takes Ϸ30 min, is thought to be complex and to involve changes in vesicle diameter (18). Maturation may impart unique morphological and physiological features to the vesicles (18)(19)(20).…”

mentioning

confidence: 99%

Regulation of large dense-core vesicle volume and neurotransmitter content mediated by adaptor protein 3

Grabner

Price

Lysakowski

et al. 2006

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

View full text Add to dashboard Cite

show abstract

“…Before exocytosis, neurosecretory vesicles are thought to be mobilized from a reserve pool to the plasma membrane, where they can dock and enter the readily releasable pool (Rizzoli and Betz, 2002;Burgoyne and Morgan, 2003;Duncan et al, 2003). To acquire fusion competence, docked vesicles need to be primed, a process requiring ATP (Bittner and Holz, 1992;Osborne et al, 2001;Rettig and Neher, 2002).…”

Section: Resultsmentioning

confidence: 99%

Phosphatidylinositol 3-Kinase C2α Is Essential for ATP-dependent Priming of Neurosecretory Granule Exocytosis

Meunier

Osborne

Hammond

et al. 2005

MBoC

102

108

View full text Add to dashboard Cite

Neurotransmitter release and hormonal secretion are highly regulated processes culminating in the calcium-dependent fusion of secretory vesicles with the plasma membrane. Here, we have identified a role for phosphatidylinositol 3-kinase C2␣ (PI3K-C2␣) and its main catalytic product, PtdIns3P, in regulated exocytosis. In neuroendocrine cells, PI3K-C2␣ is present on a subpopulation of mature secretory granules. Impairment of PI3K-C2␣ function specifically inhibits the ATP-dependent priming phase of exocytosis. Overexpression of wild-type PI3K-C2␣ enhanced secretion, whereas transfection of PC12 cells with a catalytically inactive PI3K-C2␣ mutant or a 2xFYVE domain sequestering PtdIns3P abolished secretion. Based on these results, we propose that production of PtdIns3P by PI3K-C2␣ is required for acquisition of fusion competence in neurosecretion. INTRODUCTIONThe analysis of the molecular mechanism controlling neuroexocytosis has been greatly helped by studies on neurosecretory cells (Dunn and Holz, 1983;Sarafian et al., 1987;Martin and Walent, 1989;Monck and Fernandez, 1994;Rettig and Neher, 2002). Early work has shed light on two major steps consisting of the reversible ATP-dependent priming of docked granules followed by their Ca 2ϩ -driven fusion with the plasma membrane and release of the granule content (Holz et al., 1989;Hay and Martin, 1992). The spatiotemporal control of intracellular Ca 2ϩ concentration together with capacitance measurements has allowed the identification of distinct pools of chromaffin granules involved in these distinct steps (Rettig and Neher, 2002). Further electrophysiological and biochemical approaches, such as the reconstitution of secretion in permeabilized neurosecretory cells (Martin and Walent, 1989), have highlighted the role of key factors involved in these two processes. Cytosolic and membrane proteins have been linked to priming and fusion, including the mammalian orthologues of the Caenorhabditis elegans UNC13 and UNC18 gene products, synaptotagmins, and members of the SNARE family and associated proteins (Jahn and Sudhof, 1999;Burgoyne et al., 2001;Brose and Rosenmund, 2002;Rettig and Neher, 2002).In contrast, less is known about the contribution of lipid dynamics during these processes with the exception of phosphatidic acid and phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P 2 ]. The former is produced by phospholipase D, which is essential for secretion in neurons (Humeau et al., 2001) and in neuroendocrine cells . The inhibition of Ca 2ϩ -dependent catecholamine release after depletion of phosphatidylinositol highlighted the role of phosphoinositides during the secretory events (Eberhard et al., 1990). Moreover, phosphatidylinositol transfer protein and phosphatidylinositol-4-phosphate 5 kinase (PI4P5K) were shown to be required for the ATP-dependent priming of secretory granules in PC12 cells (Hay and Martin, 1993;Hay et al., 1995). In addition, phosphatidylinositol 4-kinase (PI4K), an integral membrane protein of chromaffin granules and synaptic vesicles, is r...

show abstract

“…These pre-docked SGs sit on the PM for a long time until Ca 2+ release is evoked to trigger exocytosis, accounting for firstphase GSIS [1,2,20]. When pre-docked SGs sit on the PM too long, some lose exocytosis competence; this has been blamed on an undefined 'ageing' process [28]. This defect is believed to be accentuated in pancreatic islet beta cells in type 2 diabetes.…”

Section: Discussionmentioning

confidence: 99%

Syntaxin-4 mediates exocytosis of pre-docked and newcomer insulin granules underlying biphasic glucose-stimulated insulin secretion in human pancreatic beta cells

et al. 2015

View full text Add to dashboard Cite

Aims/hypothesis Of the four exocytotic syntaxins (Syns), much is now known about the role of Syn-1A (pre-docked secretory granules [SGs]) and Syn-3 (newcomer SGs) in insulin exocytosis. Some work was reported on Syn-4's role in biphasic glucose-stimulated insulin secretion (GSIS), but its precise role in insulin SG exocytosis remains unclear. In this paper we examine this role in human beta cells. Methods Endogenous function of Syn-4 in human islets was assessed by knocking down its expression with lentiviral single hairpin RNA (lenti-shRNA)-RFP. Biphasic GSIS was determined by islet perifusion assay. Single-cell analysis of exocytosis of red fluorescent protein (RFP)-positive beta cells (exhibiting near-total depletion of Syn-4) was by patch clamp capacitance measurements (Cm) and total internal reflection fluorescence microscopy (TIRFM), the latter to further assess single SG behaviour. Co-immunoprecipitations were conducted on INS-1 cells to assess exocytotic complexes. Results Syn-4 knockdown (KD) of 77% in human islets caused a concomitant reduction in cognate Munc18c expression (46%) without affecting expression of other exocytotic proteins; this resulted in reduction of GSIS in the first phase (by 42%) and the second phase (by 40%). Cm of RFP-tagged Syn-4-KD beta cells showed severe inhibition in the readily releasable pool (by 71%) and mobilisation from reserve pools (by 63%). TIRFM showed that Syn-4-KD-induced inhibition of first-phase GSIS was attributed to reduction in exocytosis of both pre-docked and newcomer SGs (which undergo minimal residence or docking time at the plasma membrane before fusion). Second-phase inhibition was attributed to reduction in newcomer SGs. Stx-4 co-immunoprecipitated Munc18c, VAMP2 and VAMP8, suggesting that these exocytotic complexes may be involved in exocytosis of pre-docked and newcomer SGs. Conclusions/interpretation Syn-4 is involved in distinct molecular machineries that influence exocytosis of both predocked and newcomer SGs in a manner functionally redundant to Syn-1A and Syn-3, respectively; this underlies Syn-4's role in mediating portions of first-phase and second-phase GSIS.

show abstract

Functional and spatial segregation of secretory vesicle pools according to vesicle age

Cited by 198 publications

References 25 publications

Regulation of large dense-core vesicle volume and neurotransmitter content mediated by adaptor protein 3

Regulation of large dense-core vesicle volume and neurotransmitter content mediated by adaptor protein 3

Phosphatidylinositol 3-Kinase C2α Is Essential for ATP-dependent Priming of Neurosecretory Granule Exocytosis

Syntaxin-4 mediates exocytosis of pre-docked and newcomer insulin granules underlying biphasic glucose-stimulated insulin secretion in human pancreatic beta cells

Contact Info

Product

Resources

About