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 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.

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

scholarly journals Loss of the Zymogen Granule Protein Syncollin Affects Pancreatic Protein Synthesis and Transport but Not Secretion

2002 ◽  
Vol 22 (5) ◽  
pp. 1545-1554 ◽  
Author(s):  
Wolfram Antonin ◽  
Martin Wagner ◽  
Dietmar Riedel ◽  
Nils Brose ◽  
Reinhard Jahn
Keyword(s):  
Protein Synthesis ◽  
Intracellular Transport ◽  
Release Kinetics ◽  
Pancreatic Acinar Cells ◽  
Secretory Proteins ◽  
Zymogen Granule ◽  
Zymogen Granules ◽  
Granule Membrane ◽  
Deficient Mice ◽  
Shed Light

ABSTRACT Syncollin is a small protein that is abundantly expressed in pancreatic acinar cells and that is tightly associated with the lumenal side of the zymogen granule membrane. To shed light on the hitherto unknown function of syncollin, we have generated syncollin-deficient mice. The mice are viable and show a normal pancreatic morphology as well as normal release kinetics in response to secretagogue stimulation. Although syncollin is highly enriched in zymogen granules, no change was found in the overall protein content and in the levels of chymotrypsin, trypsin, and amylase. However, syncollin-deficient mice reacted to caerulein hyperstimulation with a more severe pancreatitis. Furthermore, the rates of both protein synthesis and intracellular transport of secretory proteins were reduced. We conclude that syncollin plays a role in maturation and/or concentration of zymogens in zymogen granules.

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 INTRACELLULAR TRANSPORT OF SECRETORY PROTEINS IN THE PANCREATIC EXOCRINE CELL

1967 ◽  
Vol 34 (2) ◽  
pp. 577-596 ◽  
Author(s):  
James D. Jamieson ◽  
George E. Palade
Keyword(s):  
Guinea Pig ◽  
Golgi Complex ◽  
Structural Damage ◽  
Intracellular Transport ◽  
Secretory Proteins ◽  
Zymogen Granule ◽  
Cell Fractionation ◽  
Secretory Cycle ◽  
Pancreatic Exocrine ◽  
Rough Er

It has been established by electron microscopic radioautography of guinea pig pancreatic exocrine cells (Caro and Palade, 1964) that secretory proteins are transported from the elements of the rough-surfaced endoplasmic reticulum (ER) to condensing vacuoles of the Golgi complex possibly via small vesicles located in the periphery of the complex. To define more clearly the role of these vesicles in the intracellular transport of secretory proteins, we have investigated the secretory cycle of the guinea pig pancreas by cell fractionation procedures applied to pancreatic slices incubated in vitro. Such slices remain viable for 3 hr and incur minimal structural damage in this time. Their secretory proteins can be labeled with radioactive amino acids in short, well defined pulses which, followed by cell fractionation, makes possible a kinetic analysis of transport. To determine the kinetics of transport, we pulse-labeled sets of slices for 3 min with leucine-14C and incubated them for further +7, +17, and +57 min in chase medium. At each time, smooth microsomes ( = peripheral elements of the Golgi complex) and rough microsomes ( = elements of the rough ER) were isolated from the slices by density gradient centrifugation of the total microsomal fraction. Labeled proteins appeared initially (end of pulse) in the rough microsomes and were subsequently transferred during incubation in chase medium to the smooth microsomes, reaching a maximal concentration in this fraction after +7 min chase incubation. Later, labeled proteins left the smooth microsomes to appear in the zymogen granule fraction. These data provide direct evidence that secretory proteins are transported from the cisternae of the rough ER to condensing vacuoles via the small vesicles of the Golgi complex.

scholarly journals Intracellular transport and storage of secretory proteins in relation to cytodifferentiation in neoplastic pancreatic acinar cells.

1983 ◽  
Vol 96 (4) ◽  
pp. 949-960 ◽  
Author(s):  
M J Becich ◽  
M Bendayan ◽  
J K Reddy
Keyword(s):  
Golgi Apparatus ◽  
Secretory Granule ◽  
Intracellular Transport ◽  
Secretory Granules ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Process ◽  
Secretory Proteins ◽  
Neoplastic Cells ◽  
Golgi Vesicles

The pancreatic acinar carcinoma established in rat by Reddy and Rao (1977, Science 198:78-80) demonstrates heterogeneity of cytodifferentiation ranging from cells containing abundant well-developed secretory granules to those with virtually none. We examined the synthesis intracellular transport and storage of secretory proteins in secretory granule-enriched (GEF) and secretory granule-deficient (GDF) subpopulations of neoplastic acinar cells separable by Percoll gradient centrifugation, to determine the secretory process in cells with distinctly different cytodifferentiation. The cells pulse-labeled with [3H]leucine for 3 min and chase incubated for up to 4 h were analyzed by quantitative electron microscope autoradiography. In GEF neoplastic cells, the results of grain counts and relative grain density estimates establish that the label moves successively from rough endoplasmic reticulum (RER) leads to the Golgi apparatus leads to post-Golgi vesicles (vacuoles or immature granules) leads to mature secretory granules, in a manner reminiscent of the secretory process in normal pancreatic acinar cells. The presence of approximately 40% of the label in association with secretory granules at 4 h postpulse indicates that GEF neoplastic cells retain (acquire) the essential regulatory controls of the secretory process. In GDF neoplastic acinar cells the drainage of label from RER is slower, but the peak label of approximately 20% in the Golgi apparatus is reached relatively rapidly (10 min postpulse). The movement of label from the Golgi to the post-Golgi vesicles is evident; further delineation of the secretory process in GDF neoplastic cells, however, was not possible due to lack of secretory granule differentiation. The movement of label from RER leads to the Golgi apparatus leads to the post-Golgi vesicles suggests that GDF neoplastic cells also synthesize secretory proteins, but to a lesser extent than the GEF cells. The reason(s) for the inability of GDF cells to concentrate and store exportable proteins remain to be elucidated.

Membranes and membrane surfaces: Dynamics of cytoplasmic membranes in pancreatic acinar cells

1974 ◽  
Vol 268 (891) ◽  
pp. 39-53 ◽  
Keyword(s):  
Intracellular Transport ◽  
Polyacrylamide Gel Electrophoresis ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Secretory Proteins ◽  
Turnover Rates ◽  
Membrane Surfaces ◽  
Random Fashion ◽  
In Series

In pancreatic acinar cells the intracellular transport of secretory proteins occurs through the inter-connexion of distinct membrane-bounded compartments: in series, the rough surfaced endoplasmic reticulum (r.e.r.), the Golgi complex (g.c.) and the secretory (zymogen) granules (z.g.). The latter organelles are able to fuse their membrane with the plasmalemma (pm.) and discharge their content by exocytosis. In order to investigate the mechanisms by which the intracellular transport occurs we have investigated the composition as well as the rate of synthesis and turnover of the various membranes involved in the process. We found that these membranes have distinct differences in chemical composition and in the distribution of enzyme activities and that their rate of turnover is much slower than that of secretory proteins. Furthermore, SDS polyacrylamide gel electrophoresis of doubly labelled membrane proteins revealed that in each of these membranes there is a marked heterogeneity of turnover rates. These data indicate ( a ) that the membranes participating in the intracellular transport interact with one another in a non-random fashion, ( b ) that they are not synthesized concomitantly with the secretion products, ( c ) that membranes are synthesized independently from one another, and ( d ) that they are re-utilized in several secretory cycles. Consistent with these results, a model explaining the role of cellular membranes in protein secretion is described. It is proposed that the intracellular transport is effected through the specific non-random interaction (fusion-fission) and recycling of the various participating membranes. The possible relevance of these findings to other secretory systems is discussed.

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.

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