scholarly journals News about non-secretory exocytosis: mechanisms, properties, and functions

2019 ◽  
Vol 11 (9) ◽  
pp. 736-746 ◽  
Author(s):  
Rosalba D’Alessandro ◽  
Jacopo Meldolesi
Keyword(s):  
Plasma Membrane ◽  
Extracellular Space ◽  
The Other ◽  
Membrane Repair ◽  
Attachment Protein ◽  
Receptor Complexes ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Golgi Network ◽  
Factor Attachment Protein Receptor

AbstractThe fusion by exocytosis of many vesicles to the plasma membrane induces the discharge to the extracellular space of their abundant luminal cargoes. Other exocytic vesicles, however, do not contain cargoes, and thus, their fusion is not followed by secretion. Therefore, two distinct processes of exocytosis exist, one secretory and the other non-secretory. The present review deals with the knowledge of non-secretory exocytosis developed during recent years. Among such developments are the dual generation of the exocytic vesicles, initially released either from the trans-Golgi network or by endocytosis; their traffic with activation of receptors, channels, pumps, and transporters; the identification of their tethering and soluble N-ethylmaleimide-sensitive factor attachment protein receptor complexes that govern membrane fusions; the growth of axons and the membrane repair. Examples of potential relevance of these processes for pathology and medicine are also reported. The developments presented here offer interesting chances for future progress in the field.

scholarly journals Localization, Dynamics, and Protein Interactions Reveal Distinct Roles for ER and Golgi SNAREs

1998 ◽  
Vol 141 (7) ◽  
pp. 1489-1502 ◽  
Author(s):  
Jesse C. Hay ◽  
Judith Klumperman ◽  
Viola Oorschot ◽  
Martin Steegmaier ◽  
Christin S. Kuo ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Protein Interactions ◽  
The Other ◽  
Snare Proteins ◽  
Attachment Protein ◽  
Golgi Transport ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Coated Membranes ◽  
Factor Attachment Protein Receptor

ER-to-Golgi transport, and perhaps intraGolgi transport involves a set of interacting soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) proteins including syntaxin 5, GOS-28, membrin, rsec22b, and rbet1. By immunoelectron microscopy we find that rsec22b and rbet1 are enriched in COPII-coated vesicles that bud from the ER and presumably fuse with nearby vesicular tubular clusters (VTCs). However, all of the SNAREs were found on both COPII- and COPI-coated membranes, indicating that similar SNARE machinery directs both vesicle pathways. rsec22b and rbet1 do not appear beyond the first Golgi cisterna, whereas syntaxin 5 and membrin penetrate deeply into the Golgi stacks. Temperature shifts reveal that membrin, rsec22b, rbet1, and syntaxin 5 are present together on membranes that rapidly recycle between peripheral and Golgi-centric locations. GOS-28, on the other hand, maintains a fixed localization in the Golgi. By immunoprecipitation analysis, syntaxin 5 exists in at least two major subcomplexes: one containing syntaxin 5 (34-kD isoform) and GOS-28, and another containing syntaxin 5 (41- and 34-kD isoforms), membrin, rsec22b, and rbet1. Both subcomplexes appear to involve direct interactions of each SNARE with syntaxin 5. Our results indicate a central role for complexes among rbet1, rsec22b, membrin, and syntaxin 5 (34 and 41 kD) at two membrane fusion interfaces: the fusion of ER-derived vesicles with VTCs, and the assembly of VTCs to form cis-Golgi elements. The 34-kD syntaxin 5 isoform, membrin, and GOS-28 may function in intraGolgi transport.

scholarly journals Characterization of VAMP isoforms in 3T3-L1 adipocytes: implications for GLUT4 trafficking

2015 ◽  
Vol 26 (3) ◽  
pp. 530-536 ◽  
Author(s):  
Jessica B. A. Sadler ◽  
Nia J. Bryant ◽  
Gwyn W. Gould
Keyword(s):  
Plasma Membrane ◽  
Snare Complex ◽  
Cell Type ◽  
Attachment Protein ◽  
Systematic Analysis ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Factor Attachment Protein Receptor

The fusion of GLUT4-containing vesicles with the plasma membrane of adipocytes is a key facet of insulin action. This process is mediated by the formation of functional soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) complexes between the plasma membrane t-SNARE complex and the vesicle v-SNARE or VAMP. The t-SNARE complex consists of Syntaxin4 and SNAP23, and whereas many studies identify VAMP2 as the v-SNARE, others suggest that either VAMP3 or VAMP8 may also fulfil this role. Here we characterized the levels of expression, distribution, and association of all the VAMPs expressed in 3T3-L1 adipocytes to provide the first systematic analysis of all members of this protein family for any cell type. Despite our finding that all VAMP isoforms form SDS-resistant SNARE complexes with Syntaxin4/SNAP23 in vitro, a combination of levels of expression (which vary by >30-fold), subcellular distribution, and coimmunoprecipitation analyses lead us to propose that VAMP2 is the major v-SNARE involved in GLUT4 trafficking to the surface of 3T3-L1 adipocytes.

scholarly journals Rab5 regulates macropinocytosis by recruiting the inositol 5-phosphatases OCRL and Inpp5b that hydrolyse PtdIns(4,5)P2

2021 ◽  
Vol 134 (7) ◽  
Author(s):  
Michelle E. Maxson ◽  
Helen Sarantis ◽  
Allen Volchuk ◽  
John H. Brumell ◽  
Sergio Grinstein
Keyword(s):  
Plasma Membrane ◽  
Mode Of Action ◽  
Dominant Negative ◽  
Circular Membrane ◽  
Fusion Event ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Phosphatidylinositol 4 ◽  
Factor Attachment Protein Receptor

ABSTRACT Rab5 is required for macropinosome formation, but its site and mode of action remain unknown. We report that Rab5 acts at the plasma membrane, downstream of ruffling, to promote macropinosome sealing and scission. Dominant-negative Rab5, which obliterates macropinocytosis, had no effect on the development of membrane ruffles. However, Rab5-containing vesicles were recruited to circular membrane ruffles, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-dependent endomembrane fusion was necessary for the completion of macropinocytosis. This fusion event coincided with the disappearance of PtdIns(4,5)P2 that accompanies macropinosome closure. Counteracting the depletion of PtdIns(4,5)P2 by expression of phosphatidylinositol-4-phosphate 5-kinase impaired macropinosome formation. Importantly, we found that the removal of PtdIns(4,5)P2 is dependent on Rab5, through the Rab5-mediated recruitment of the inositol 5-phosphatases OCRL and Inpp5b, via APPL1. Knockdown of OCRL and Inpp5b, or APPL1, prevented macropinosome closure without affecting ruffling. We therefore propose that Rab5 is essential for the clearance of PtdIns(4,5)P2 needed to complete the scission of macropinosomes or to prevent their back-fusion with the plasmalemma.

scholarly journals Syntaxin 16 is a master recruitment factor for cytokinesis

2013 ◽  
Vol 24 (23) ◽  
pp. 3663-3674 ◽  
Author(s):  
Hélia Neto ◽  
Alexandra Kaupisch ◽  
Louise L. Collins ◽  
Gwyn W. Gould
Keyword(s):  
Membrane Vesicles ◽  
Attachment Protein ◽  
Recycling Endosome ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Late Telophase ◽  
Intracellular Organelles ◽  
Factor Attachment Protein Receptor

Recently it was shown that both recycling endosome and endosomal sorting complex required for transport (ESCRT) components are required for cytokinesis, in which they are believed to act in a sequential manner to bring about secondary ingression and abscission, respectively. However, it is not clear how either of these complexes is targeted to the midbody and whether their delivery is coordinated. The trafficking of membrane vesicles between different intracellular organelles involves the formation of soluble N-ethylmalei­mide–sensitive factor attachment protein receptor (SNARE) complexes. Although membrane traffic is known to play an important role in cytokinesis, the contribution and identity of intracellular SNAREs to cytokinesis remain unclear. Here we demonstrate that syntaxin 16 is a key regulator of cytokinesis, as it is required for recruitment of both recycling endosome–associated Exocyst and ESCRT machinery during late telophase, and therefore that these two distinct facets of cytokinesis are inextricably linked.

scholarly journals Munc18-1 domain-1 controls vesicle docking and secretion by interacting with syntaxin-1 and chaperoning it to the plasma membrane

2011 ◽  
Vol 22 (21) ◽  
pp. 4134-4149 ◽  
Author(s):  
Gayoung A. Han ◽  
Nancy T. Malintan ◽  
Ner Mu Nar Saw ◽  
Lijun Li ◽  
Liping Han ◽  
...  
Keyword(s):  
Molecular Chaperone ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Attachment Protein ◽  
Vesicle Docking ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Intracellular Expression ◽  
Factor Attachment Protein Receptor

Munc18-1 plays pleiotropic roles in neurosecretion by acting as 1) a molecular chaperone of syntaxin-1, 2) a mediator of dense-core vesicle docking, and 3) a priming factor for soluble N-ethylmaleimide–sensitive factor attachment protein receptor–mediated membrane fusion. However, how these functions are executed and whether they are correlated remains unclear. Here we analyzed the role of the domain-1 cleft of Munc18-1 by measuring the abilities of various mutants (D34N, D34N/M38V, K46E, E59K, K46E/E59K, K63E, and E66A) to bind and chaperone syntaxin-1 and to restore the docking and secretion of dense-core vesicles in Munc18-1/-2 double-knockdown cells. We identified striking correlations between the abilities of these mutants to bind and chaperone syntaxin-1 with their ability to restore vesicle docking and secretion. These results suggest that the domain-1 cleft of Munc18-1 is essential for binding to syntaxin-1 and thereby critical for its chaperoning, docking, and secretory functions. Our results demonstrate that the effect of the alleged priming mutants (E59K, D34N/M38V) on exocytosis can largely be explained by their reduced syntaxin-1–chaperoning functions. Finally, our data suggest that the intracellular expression and distribution of syntaxin-1 determines the level of dense-core vesicle docking.

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