scholarly journals Disruption of endoplasmic reticulum to Golgi transport leads to the accumulation of large aggregates containing beta-COP in pancreatic acinar cells.

1993 ◽  
Vol 4 (4) ◽  
pp. 413-424 ◽  
Author(s):  
L C Hendricks ◽  
M McCaffery ◽  
G E Palade ◽  
M G Farquhar
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Brefeldin A ◽  
Acinar Cells ◽  
Atp Depletion ◽  
Pancreatic Acinar Cells ◽  
Coat Proteins ◽  
Golgi Membranes ◽  
Golgi Transport ◽  
Transport Vesicles

When transport between the rough endoplasmic reticulum (ER) and Golgi complex is blocked by Brefeldin A (BFA) treatment or ATP depletion, the Golgi apparatus and associated transport vesicles undergo a dramatic reorganization. Because recent studies suggest that coat proteins such as beta-COP play an important role in the maintenance of the Golgi complex, we have used immunocytochemistry to determine the distribution of beta-COP in pancreatic acinar cells (PAC) in which ER to Golgi transport was blocked by BFA treatment or ATP depletion. In controls, beta-COP was associated with Golgi cisternae and transport vesicles as expected. Upon BFA treatment, PAC Golgi cisternae are dismantled and replaced by clusters of remnant vesicles surrounded by typical ER transitional elements that are generally assumed to represent the exit site of vesicular carriers for ER to Golgi transport. In BFA-treated PAC, beta-COP was concentrated in large (0.5-1.0 micron) aggregates closely associated with remnant Golgi membranes. In addition to typical ER transitional elements, we detected a new type of transitional element that consists of specialized regions of rough ER (RER) with ribosome-free ends that touched or extended into the beta-COP containing aggregates. In ATP-depleted PAC, beta-COP was not detected on Golgi membranes but was concentrated in similar large aggregates found on the cis side of the Golgi stacks. The data indicate that upon arrest of ER to Golgi transport by either BFA treatment or energy depletion, beta-COP dissociates from PAC Golgi membranes and accumulates as large aggregates closely associated with specialized ER elements. The latter may correspond to either the site of entry or exit for vesicles recycling between the Golgi and the RER.

scholarly journals ADP-ribosylation factor and coatomer couple fusion to vesicle budding

1994 ◽  
Vol 124 (4) ◽  
pp. 415-424 ◽  
Author(s):  
Z Elazar ◽  
L Orci ◽  
J Ostermann ◽  
M Amherdt ◽  
G Tanigawa ◽  
...  
Keyword(s):  
Brefeldin A ◽  
Retrograde Transport ◽  
Coated Vesicles ◽  
Coat Proteins ◽  
Vesicle Budding ◽  
Adp Ribosylation ◽  
Golgi Membranes ◽  
Transport Vesicles ◽  
Donor And Acceptor ◽  
Adp Ribosylation Factor

The coat proteins required for budding COP-coated vesicles from Golgi membranes, coatomer and ADP-ribosylation factor (ARF) protein, are shown to be required to reconstitute the orderly process of transport between Golgi cisternae in which fusion of transport vesicles begins only after budding ends. When either coat protein is omitted, fusion is uncoupled from budding-donor and acceptor compartments pair directly without an intervening vesicle. Coupling may therefore results from the sequestration of fusogenic membrane proteins into assembling coated vesicles that are only exposed when the coat is removed after budding is complete. This mechanism of coupling explains the phenomenon of "retrograde transport" triggered by uncouplers such as the drug brefeldin A.

scholarly journals Role of NAD+ and ADP-Ribosylation in the Maintenance of the Golgi Structure

1997 ◽  
Vol 139 (5) ◽  
pp. 1109-1118 ◽  
Author(s):  
Alexander Mironov ◽  
Antonino Colanzi ◽  
Maria Giuseppina Silletta ◽  
Giusy Fiucci ◽  
Silvio Flati ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Golgi Complex ◽  
Brefeldin A ◽  
Coat Proteins ◽  
Cytosolic Proteins ◽  
Permeabilized Cells ◽  
Adp Ribosylation ◽  
Golgi Membranes ◽  
Golgi Structure

We have investigated the role of the ADP- ribosylation induced by brefeldin A (BFA) in the mechanisms controlling the architecture of the Golgi complex. BFA causes the rapid disassembly of this organelle into a network of tubules, prevents the association of coatomer and other proteins to Golgi membranes, and stimulates the ADP-ribosylation of two cytosolic proteins of 38 and 50 kD (GAPDH and BARS-50; De Matteis, M.A., M. DiGirolamo, A. Colanzi, M. Pallas, G. Di Tullio, L.J. McDonald, J. Moss, G. Santini, S. Bannykh, D. Corda, and A. Luini. 1994. Proc. Natl. Acad. Sci. USA. 91:1114–1118; Di Girolamo, M., M.G. Silletta, M.A. De Matteis, A. Braca, A. Colanzi, D. Pawlak, M.M. Rasenick, A. Luini, and D. Corda. 1995. Proc. Natl. Acad. Sci. USA. 92:7065–7069). To study the role of ADP-ribosylation, this reaction was inhibited by depletion of NAD+ (the ADP-ribose donor) or by using selective pharmacological blockers in permeabilized cells. In NAD+-depleted cells and in the presence of dialized cytosol, BFA detached coat proteins from Golgi membranes with normal potency but failed to alter the organelle's structure. Readdition of NAD+ triggered Golgi disassembly by BFA. This effect of NAD+ was mimicked by the use of pre–ADP- ribosylated cytosol. The further addition of extracts enriched in native BARS-50 abolished the ability of ADP-ribosylated cytosol to support the effect of BFA. Pharmacological blockers of the BFA-dependent ADP-ribosylation (Weigert, R., A. Colanzi, A. Mironov, R. Buccione, C. Cericola, M.G. Sciulli, G. Santini, S. Flati, A. Fusella, J. Donaldson, M. DiGirolamo, D. Corda, M.A. De Matteis, and A. Luini. 1997. J. Biol. Chem. 272:14200–14207) prevented Golgi disassembly by BFA in permeabilized cells. These inhibitors became inactive in the presence of pre–ADP-ribosylated cytosol, and their activity was rescued by supplementing the cytosol with a native BARS-50–enriched fraction. These results indicate that ADP-ribosylation plays a role in the Golgi disassembling activity of BFA, and suggest that the ADP-ribosylated substrates are components of the machinery controlling the structure of the Golgi apparatus.

scholarly journals Effect of colchicine on the Golgi complex of rat pancreatic acinar cells.

1983 ◽  
Vol 97 (3) ◽  
pp. 737-748 ◽  
Author(s):  
M Pavelka ◽  
A Ellinger
Keyword(s):  
Golgi Complex ◽  
Acinar Cells ◽  
Colchicine Treatment ◽  
Pancreatic Acinar Cells ◽  
Zymogen Granules ◽  
Reaction Products ◽  
Transport Vesicles ◽  
Secretion Granules ◽  
Thiamine Pyrophosphatase ◽  
Inosine Diphosphatase

Colchicine administered to adult rats at a dosage of 0.5 mg/100 g of body weight effected a disorganization of the Golgi apparatus in pancreatic acinar cells. The results obtained after various periods of treatment (10 min to 6 h) showed (a) changes in all components of the Golgi complex, and (b) occurrence of large vacuoles that predominated in cytoplasmic areas outside the Golgi region. The alterations in Golgi stacks concerned elements of the proximal and distal side: (a) accumulation of transport vesicles, (b) formation of small, polymorphic secretion granules, and (c) alterations in the cytochemical localization of enzymes and reaction product after osmification. Transport vesicles accumulated and accompanied short, dilated cisternae, which lack mostly the reaction products of thiamine pyrophosphatase, inosine diphosphatase, and acid phosphatase, and osmium deposits after prolonged osmification. After 4 to 6 h of treatment, accumulated transport vesicles occupied extensive cellular areas; stacked cisternae were not demonstrable in these regions. The changes on the distal Golgi side included GERL elements: condensing vacuoles were diminished; they were substituted by small, polymorphic zymogen granules, which appeared to be formed by distal Golgi cisternae and by rigid lamellae. Unusually extended coated regions covered condensing vacuoles, rigid lamellae, and polymorphic secretion granules. A cytochemical distinction between Golgi components and GERL was possible neither in controls nor after colchicine treatment. The cytochemical alterations in Golgi components were demonstrable 20-30 min following administration of colchicine; at 45 min, initial morphological changes--augmentation of transport vesicles and formation of polymorphic zymogen granules--became apparent. 20 min after administration of colchicine, conspicuous groups of large vacuoles occurred. They were located mostly in distinct fields between cisternae of the endoplasmic reticulum, and were accompanied by small osmium--reactive vesicles. Stacked cisternae were not demonstrable in these fields. Vacuoles and vesicles were devoid of reaction products of thiamine pyrophosphatase, inosine diphosphatase, and acid phosphatase. The results provide evidence that formation of stacked Golgi cisternae is impaired after colchicine treatment. The colchicine--induced disintegration of the Golgi complex suggests a regulatory function of microtubules in the organization of the Golgi apparatus.

scholarly journals Redistribution of a rab3-like GTP-binding protein from secretory granules to the Golgi complex in pancreatic acinar cells during regulated exocytosis

1994 ◽  
Vol 124 (1) ◽  
pp. 43-53 ◽  
Author(s):  
BP Jena ◽  
FD Gumkowski ◽  
EM Konieczko ◽  
GF von Mollard ◽  
R Jahn ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Golgi Complex ◽  
Binding Protein ◽  
Secretory Granules ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Apical Plasma Membrane ◽  
Gtp Binding Protein ◽  
Regulated Exocytosis ◽  
Gtp Binding

Regulated secretion from pancreatic acinar cells occurs by exocytosis of zymogen granules (ZG) at the apical plasmalemma. ZGs originate from the TGN and undergo prolonged maturation and condensation. After exocytosis, the zymogen granule membrane (ZGM) is retrieved from the plasma membrane and ultimately reaches the TGN. In this study, we analyzed the fate of a low M(r) GTP-binding protein during induced exocytosis and membrane retrieval using immunoblots as well as light and electron microscopic immunocytochemistry. This 27-kD protein, identified by a monoclonal antibody that recognizes rab3A and B, may be a novel rab3 isoform. In resting acinar cells, the rab3-like protein was detected primarily on the cytoplasmic face of ZGs, with little labeling of the Golgi complex and no significant labeling of the apical plasmalemma or any other intracellular membranes. Stimulation of pancreatic lobules in vitro by carbamylcholine for 15 min, resulted in massive exocytosis that led to a near doubling of the area of the apical plasma membrane. However, no relocation of the rab3-like protein to the apical plasmalemma was seen. After 3 h of induced exocytosis, during which time approximately 90% of the ZGs is released, the rab3-like protein appeared to translocate to small vesicles and newly forming secretory granules in the TGN. No significant increase of the rab3-like protein was found in the cytosolic fraction at any time during stimulation. Since the protein is not detected on the apical plasmalemma after stimulation, we conclude that recycling may involve a membrane dissociation-association cycle that accompanies regulated exocytosis.

scholarly journals Vesicular and uncoated Rab1-dependent cargo carriers facilitate ER to Golgi transport

2020 ◽  
Vol 133 (14) ◽  
pp. jcs239814 ◽  
Author(s):  
Laura M. Westrate ◽  
Melissa J. Hoyer ◽  
Michael J. Nash ◽  
Gia K. Voeltz
Keyword(s):  
Endoplasmic Reticulum ◽  
De Novo ◽  
Coated Vesicle ◽  
First Person ◽  
Coat Proteins ◽  
Animal Cells ◽  
Golgi Transport ◽  
Er Exit Sites ◽  
Copii Vesicles ◽  
Export System

ABSTRACTSecretory cargo is recognized, concentrated and trafficked from endoplasmic reticulum (ER) exit sites (ERES) to the Golgi. Cargo export from the ER begins when a series of highly conserved COPII coat proteins accumulate at the ER and regulate the formation of cargo-loaded COPII vesicles. In animal cells, capturing live de novo cargo trafficking past this point is challenging; it has been difficult to discriminate whether cargo is trafficked to the Golgi in a COPII-coated vesicle. Here, we describe a recently developed live-cell cargo export system that can be synchronously released from ERES to illustrate de novo trafficking in animal cells. We found that components of the COPII coat remain associated with the ERES while cargo is extruded into COPII-uncoated, non-ER associated, Rab1 (herein referring to Rab1a or Rab1b)-dependent carriers. Our data suggest that, in animal cells, COPII coat components remain stably associated with the ER at exit sites to generate a specialized compartment, but once cargo is sorted and organized, Rab1 labels these export carriers and facilitates efficient forward trafficking.This article has an associated First Person interview with the first author of the paper.

scholarly journals Influenza virus hemagglutinin trimers and monomers maintain distinct biochemical modifications and intracellular distribution in brefeldin A-treated cells.

1991 ◽  
Vol 2 (7) ◽  
pp. 549-563 ◽  
Author(s):  
G Russ ◽  
J R Bennink ◽  
T Bächi ◽  
J W Yewdell
Keyword(s):  
Endoplasmic Reticulum ◽  
Influenza Virus ◽  
Monoclonal Antibodies ◽  
Golgi Complex ◽  
Brefeldin A ◽  
Retrograde Transport ◽  
Cell Fractionation ◽  
Influenza Virus Hemagglutinin ◽  
Infected Cells ◽  
Vesicular Compartment

Brefeldin A (BFA) induces the retrograde transport of proteins from the Golgi complex (GC) to the endoplasmic reticulum (ER). It is uncertain, however, whether the drug completely merges the ER with post-ER compartments, or whether some of their elements remain physically and functionally distinct. We investigated this question by the use of monoclonal antibodies specific for monomers and trimers of the influenza virus hemagglutinin (HA). In untreated influenza virus-infected cells, monomers and trimers almost exclusively partition into the ER and GC, respectively. In BFA-treated cells, both monomers and trimers are detected in the ER by immunofluorescence. Cell fractionation experiments indicate, however, that whereas HA monomers synthesized in the presence of BFA reside predominantly in vesicles with a characteristic density of the ER, HA trimers are primarily located in lighter vesicles characteristic of post-ER compartments. Biochemical experiments confirm that in BFA-treated cells, trimers are more extensively modified than monomers by GC-associated enzymes. Additional immunofluorescence experiments reveal that in BFA-treated cells, HA monomers can exist in an ER subcompartment less accessible to trimers and, conversely, that trimers are present in a vesicular compartment less accessible to monomers. These findings favor the existence of a post-ER compartment for which communication with the ER is maintained in the presence of BFA and suggest that trimers cycle between this compartment and the ER, but have access to only a portion of the ER.

scholarly journals KDEL and KKXX Retrieval Signals Appended to the Same Reporter Protein Determine Different Trafficking between Endoplasmic Reticulum, Intermediate Compartment, and Golgi Complex

2003 ◽  
Vol 14 (3) ◽  
pp. 889-902 ◽  
Author(s):  
Mariano Stornaiuolo ◽  
Lavinia V. Lotti ◽  
Nica Borgese ◽  
Maria-Rosaria Torrisi ◽  
Giovanna Mottola ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Steady State ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Molecular Mechanisms ◽  
Reporter Protein ◽  
Transport Vesicles ◽  
Efficient Retrieval ◽  
Intermediate Compartment ◽  
Almost All

Many endoplasmic reticulum (ER) proteins maintain their residence by dynamic retrieval from downstream compartments of the secretory pathway. In previous work we compared the retrieval process mediated by the two signals, KKMP and KDEL, by appending them to the same neutral reporter protein, CD8, and found that the two signals determine a different steady-state localization of the reporter. CD8-K (the KDEL-bearing form) was restricted mainly to the ER, whereas CD8-E19 (the KKMP-bearing form) was distributed also to the intermediate compartment and Golgi complex. To investigate whether this different steady-state distribution reflects a difference in exit rates from the ER and/or in retrieval, we have now followed the first steps of export of the two constructs from the ER and their trafficking between ER and Golgi complex. Contrary to expectation, we find that CD8-K is efficiently recruited into transport vesicles, whereas CD8-E19 is not. Thus, the more restricted ER localization of CD8-K must be explained by a more efficient retrieval to the ER. Moreover, because most of ER resident CD8-K is not O-glycosylated but almost all CD8-E19 is, the results suggest that CD8-K is retrieved from the intermediate compartment, before reaching the Golgi, whereO-glycosylation begins. These results illustrate how different retrieval signals determine different trafficking patterns and pose novel questions on the underlying molecular mechanisms.

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