scholarly journals Possible association of chaperonin 60 with secretory proteins in pancreatic acinar cells.

1996 ◽  
Vol 44 (7) ◽  
pp. 743-749 ◽  
Author(s):  
I M Le Gall ◽  
M Bendayan
Keyword(s):  
Secretory Pathway ◽  
Active Form ◽  
Acinar Cells ◽  
Morphological Data ◽  
Pancreatic Acinar Cells ◽  
Electron Microscopic Level ◽  
Secretory Proteins ◽  
Zymogen Granule ◽  
Electron Microscopic ◽  
Rat Exocrine Pancreas

Assembly and folding of newly synthesized polypeptides, acquisition of their biological active form, and their translocation in different cellular compartments are processes assisted by molecular chaperones. Because particular chaperones have been found to be present along the RER-Golgi-granule secretory pathway in pancreatic acinar cells, we presume that they should play important roles in secretion. In the present study, applying double immunogold labeling at the electron microscopic level on rat exocrine pancreas, we have revealed the existence of a topographical association between Hsp60 and particular pancreatic enzymes along the secretory pathway. The highest association was found for amylase, lipase, and chymotrypsinogen, whereas trypsinogen and carboxypeptidase B showed much lower association values. Immunoprecipitation of isolated zymogen granule content with an anti-Hsp60 antibody appears to confirm the morphological data, since amylase and lipase were found to co-precipitate with Hsp60. These findings support the hypothesis that Hsp60 is associated with certain pancreatic proteins along the secretory pathway. Hsp60 would assist the proper folding and assembly of pancreatic secretory proteins and could also prevent their autoactivation before secretion.

scholarly journals DYNAMICS OF CYTOPLASMIC MEMBRANES IN GUINEA PIG PANCREATIC ACINAR CELLS

1974 ◽  
Vol 61 (1) ◽  
pp. 1-13 ◽  
Author(s):  
J. Meldolesi
Keyword(s):  
Molecular Weight ◽  
Membrane Proteins ◽  
Guinea Pig ◽  
Intracellular Transport ◽  
Sodium Dodecyl ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Proteins ◽  
Zymogen Granule ◽  
Double Labeling

The rate of synthesis and the turnover of cytoplasmic membrane proteins were determined in the acinar cells of guinea pig pancreas with the aim of investigating the mechanisms by which the intracellular transport of secretion products occurs. These cells are highly specialized toward protein secretion. By means of in vitro pulse-chase experiments and in vivo double-labeling experiments, using radioactive L-leucine as the tracer, it was found that the turnover of secretory proteins is much faster than that of all membranes involved in their transport (rough and smooth microsome and zymogen granule membranes). Sodium dodecyl sulfate-polyacrylamide disk gel electrophoresis of membrane proteins revealed that in each of these membranes there is a marked heterogeneity of turnover; generally the high molecular weight polypeptides have a shorter half-life than the low molecular weight polypeptides. These data indicate that the membranes participating in the intracellular transport of secretory proteins are not synthesized concomitantly with the latter. Rather, they are probably reutilized in several successive secretory cycles. The possible relevance of these findings to other secretory systems is discussed.

scholarly journals Targeting of the zymogen-granule protein syncollin in AR42J and AtT-20 cells

2000 ◽  
Vol 350 (3) ◽  
pp. 637-643 ◽  
Author(s):  
Alois HODEL ◽  
J. Michael EDWARDSON
Keyword(s):  
Secretory Pathway ◽  
Fluorescent Protein ◽  
Secretory Granules ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Cells ◽  
Apical Region ◽  
Zymogen Granule ◽  
Ar42j Cells ◽  
Green Fluorescent

Syncollin is a 13-kDa protein associated with the membranes of pancreatic zymogen granules. Here we determine the in situ localization of syncollin in pancreatic acinar cells from adult and neonatal rats, and study the targeting of green fluorescent protein-(GFP-) and His6-tagged syncollin chimaeras in model exocrine and endocrine secretory cells. Immunocytochemical analysis of the distribution of syncollin in fully differentiated and neonatal acinar cells revealed a granular pattern that corresponded with that of the zymogen-granule markers synaptobrevin 2 and amylase. In fully differentiated acinar cells syncollin-positive vesicles were detected in the apical region of the cells, whereas in neonatal acinar cells they were found clustered near the cell nucleus. Both GFP- and His6-tagged syncollin entered the secretory pathway when transiently expressed in AR42J or AtT-20 cells. Syncollin-GFP was found predominantly in amylase-positive granules in AR42J cells and in adrenocorticotrophic hormone- (ACTH-) positive granules in AtT-20 cells. Syncollin-GFP was also present in the Golgi complex in AR42J cells. Syncollin-His6 became localized in ACTH-containing granules in the neuritic processes of AtT-20 cells. In AR42J cells syncollin-His6 did not co-localize with amylase, but was detected in acidic vesicles. These results show that the exocrine protein syncollin contains intrinsic cell-type-independent targeting information that is retained in both exocrine and endocrine cells after fusion to the GFP tag. In contrast, His6-tagged syncollin is efficiently targeted to secretory granules only in AtT-20 cells and not in AR42J cells.

scholarly journals Tumor protein D52 controls trafficking of an apical endolysosomal secretory pathway in pancreatic acinar cells

2013 ◽  
Vol 305 (6) ◽  
pp. G439-G452 ◽  
Author(s):  
Scott W. Messenger ◽  
Diana D. H. Thomas ◽  
Michelle A. Falkowski ◽  
Jennifer A. Byrne ◽  
Fred S. Gorelick ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Secretory Pathway ◽  
Secretory Granules ◽  
Phosphorylation Site ◽  
Brefeldin A ◽  
Acinar Cells ◽  
Pancreatic Acinar Cell ◽  
Pancreatic Acinar Cells ◽  
Zymogen Granule ◽  
Adenoviral Delivery

Zymogen granule (ZG) formation in acinar cells involves zymogen cargo sorting from trans-Golgi into immature secretory granules (ISGs). ISG maturation progresses by removal of lysosomal membrane and select content proteins, which enter endosomal intermediates prior to their apical exocytosis. Constitutive and stimulated secretion through this mechanism is termed the constitutive-like and minor-regulated pathways, respectively. However, the molecular components that control membrane trafficking within these endosomal compartments are largely unknown. We show that tumor protein D52 is highly expressed in endosomal compartments following pancreatic acinar cell stimulation and regulates apical exocytosis of an apically directed endolysosomal compartment. Secretion from the endolysosomal compartment was detected by cell-surface antigen labeling of lysosome-associated membrane protein LAMP1, which is absent from ZGs, and had incomplete overlap with surface labeling of synaptotagmin 1, a marker of ZG exocytosis. Although culturing (16–18 h) of isolated acinar cells is accompanied by a loss of secretory responsiveness, the levels of SNARE proteins necessary for ZG exocytosis were preserved. However, levels of endolysosomal proteins D52, EEA1, Rab5, and LAMP1 markedly decreased with culture. When D52 levels were restored by adenoviral delivery, the levels of these regulatory proteins and secretion of both LAMP1 (endolysosomal) and amylase was strongly enhanced. These secretory effects were absent in alanine and aspartate substitutions of serine 136, the major D52 phosphorylation site, and were inhibited by brefeldin A, which does not directly affect the ZG compartment. Our results indicate that D52 directly regulates apical endolysosomal secretion and are consistent with previous studies, suggesting that this pathway indirectly regulates ZG secretion of digestive enzymes.

scholarly journals SYNTHESIS AND MIGRATION OF PROTEINS IN THE CELLS OF THE EXOCRINE PANCREAS AS REVEALED BY SPECIFIC ACTIVITY DETERMINATION FROM RADIOAUTOGRAPHS

1963 ◽  
Vol 16 (1) ◽  
pp. 1-23 ◽  
Author(s):  
H. Warshawsky ◽  
C. P. Leblond ◽  
B. Droz
Keyword(s):  
Specific Activity ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Zymogen Granule ◽  
Zymogen Granules ◽  
The Mean ◽  
And Migration ◽  
Rats And Mice ◽  
Silver Grains ◽  
Golgi Zone

Radioautographs of pancreatic acinar cells were prepared in rats and mice sacrificed at various times after injection of leucine-, glycine-, or methionine-H3. Measurements of radioactivity concentration (number of silver grains per unit area) and relative protein concentration (by microspectrophotometry of Millon-treated sections) yielded the mean specific activity of proteins in various regions of the acinar cells. The 2 to 5 minute radioautographs as well as the specific activity time curves demonstrate protein synthesis in ergastoplasm. From there, most newly synthesized proteins migrate to and accumulate in the Golgi zone. Then they spread to the whole zymogen region and, finally, enter the excretory ducts. An attempt at estimating turnover times indicated that two classes of proteins are synthesized in the ergastoplasm: "sedentary" with a slow turnover (62.5 hours) and "exportable" with rapid turnover (4.7 minutes). It is estimated that the exportable proteins spend approximately 11.7 minutes in the Golgi zone where they are built up into zymogen granules, and thereafter 36.0 minutes as fully formed zymogen granules, before they are released outside the acinar cell as pancreatic secretion. The mean life span of a zymogen granule in the cell is estimated to be 47.7 minutes.

scholarly journals Double immunocytochemical labeling applying the protein A-gold technique.

1982 ◽  
Vol 30 (1) ◽  
pp. 81-85 ◽  
Author(s):  
M Bendayan
Keyword(s):  
Tissue Section ◽  
Protein A ◽  
Antigenic Site ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Proteins ◽  
Zymogen Granules ◽  
Double Labeling ◽  
Gold Particles ◽  
Antigenic Sites

In the present study we report the modifications and the different steps of the protein A-gold (pAg) technique that allow the simultaneous demonstration of two antigenic sites on the same tissue section. The labeling is carried out in the following manner: face A of the tissue section is incubated with an antiserum followed by a pAg complex prepared with large gold particles; face B of the same tissue section is then incubated with a second antiserum followed by a pAg complex prepared with small gold particles. Each of the pAg complexes reveals a different antigenic site on opposite faces of the tissue section. The transparency of the section in the electron beam allows the visualization of the gold particles present on both faces. The double labeling pAg technique was applied for the simultaneous demonstration of two secretory proteins in the same Golgi, condensing vacuoles, and zymogen granules of the rat pancreatic acinar cells.

Metallothionein is a component of exocrine pancreas secretion: implications for zinc homeostasis

1996 ◽  
Vol 271 (4) ◽  
pp. C1103-C1110 ◽  
Author(s):  
R. C. De Lisle ◽  
M. P. Sarras ◽  
J. Hidalgo ◽  
G. K. Andrews
Keyword(s):  
Transgenic Mice ◽  
Pancreatic Juice ◽  
Secretory Pathway ◽  
Physiological Role ◽  
Acinar Cells ◽  
Transgenic Animals ◽  
Light Level ◽  
Zinc Homeostasis ◽  
Pancreatic Acinar Cells ◽  
Pancreatic Ducts

Using transgenic mice that overexpress metallothionein-I (MT-I) and zinc-induced normal and transgenic animals, we have explored the localization of MT in the pancreas. Light-level immunocytochemistry demonstrated MT in acinar cells but not islet cells. Immunolabeling also revealed the presence of MT in pancreatic ducts, suggesting that it is released from acinar cells. Ultrastructural immunolocalization showed that MT was cytoplasmic, and no MT immunoreactivity was detected in lumens of the vesicular secretory pathway. Secreted pancreatic juice was collected from pilocarpine-stimulated mice and assayed for MT by a 109Cd-labeled hemoglobin-exchange assay and by radioimmunoassay. Both methods revealed high (> 1,000 ng/ml) levels of MT in the stimulated secretion. The level of MT in pancreatic juice from transgenic mice was only slightly (2-fold) increased despite dramatic overexpression of MT-I in the pancreas (> 20-fold). In contrast, zinc induction of MT significantly increased MT by 5- to 10-fold in the pancreatic juice, in normal and transgenic mice. These data indicate that MT is released from pancreatic acinar cells but not by the classical vesicular secretory pathway. In addition, MT levels in pancreatic juice are regulated by zinc, suggesting a physiological role of the pancreas in metal homeostasis.

High- and Small-Molecular-Weight GTP-Binding Proteins in Zymogen Granule Membranes of Rat Pancreatic Acinar Cells

1992 ◽  
Vol 2 (2) ◽  
pp. 77-89 ◽  
Author(s):  
Susanne Schnefel ◽  
Petra Zimmermann ◽  
André Pröfrock ◽  
Reinhard Jahn ◽  
Klaus Aktories ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Binding Proteins ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Zymogen Granule ◽  
Small Molecular Weight ◽  
Gtp Binding Proteins ◽  
Gtp Binding

Cleavage of SNAP-25 and VAMP-2 impairs store-operated Ca2+entry in mouse pancreatic acinar cells

2005 ◽  
Vol 288 (1) ◽  
pp. C214-C221 ◽  
Author(s):  
Juan A. Rosado ◽  
Pedro C. Redondo ◽  
Ginés M. Salido ◽  
Stewart O. Sage ◽  
Jose A. Pariente
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Secretory Cell ◽  
Botulinum Toxin A ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Proteins ◽  
Amylase Secretion ◽  
Cell Type ◽  
Store Depletion

We recently reported that store-operated Ca2+entry (SOCE) in nonexcitable cells is likely to be mediated by a reversible interaction between Ca2+channels in the plasma membrane and the endoplasmic reticulum, a mechanism known as “secretion-like coupling.” As for secretion, in this model the actin cytoskeleton plays a key regulatory role. In the present study we have explored the involvement of the secretory proteins synaptosome-associated protein (SNAP-25) and vesicle-associated membrane protein (VAMP) in SOCE in pancreatic acinar cells. Cleavage of SNAP-25 and VAMPs by treatment with botulinum toxin A (BoNT A) and tetanus toxin (TeTx), respectively, effectively inhibited amylase secretion stimulated by the physiological agonist CCK-8. BoNT A significantly reduced Ca2+entry induced by store depletion using thapsigargin or CCK-8. In addition, treatment with BoNT A once SOCE had been activated reduced Ca2+influx, indicating that SNAP-25 is needed for both the activation and maintenance of SOCE in pancreatic acinar cells. VAMP-2 and VAMP-3 are expressed in mouse pancreatic acinar cells. Both proteins associate with the cytoskeleton upon Ca2+store depletion, although only VAMP-2 seems to be sensitive to TeTx. Treatment of pancreatic acinar cells with TeTx reduced the activation of SOCE without affecting its maintenance. These findings support a role for SNAP-25 and VAMP-2 in the activation of SOCE in pancreatic acinar cells and show parallels between this process and secretion in a specialized secretory cell type.

Sign in / Sign up

Export Citation Format

Share Document