The 1989 Upjohn Award Lecture. Cellular and molecular mechanisms in hormone and neurotransmitter secretion

1990 ◽  
Vol 68 (1) ◽  
pp. 1-16 ◽  
Author(s):  
José-María Trifaró
Keyword(s):  
Adrenal Medulla ◽  
Chromaffin Cells ◽  
Secretory Cell ◽  
Secretory Granules ◽  
Secretory Process ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
Cell Secretion ◽  
Chromaffin Granule ◽  
Calmodulin Binding

Studies on adrenal medulla have had an important influence on the development of a variety of biological concepts, not only within the area of endocrinology, but also in the areas of chemical neurotransmission and secretion in general. The adrenal medulla chromaffin cells are derived embryologically from the neural crest, sharing a common origin with sympathetic neurons and common subcellular features with many endocrine cells. One such feature is the storage of secretory products in membrane-bound organelles, the secretory granules. Secretory cells with these characteristics have been named paraneurons, a term that embraces cells generally and traditionally not considered as neurons, and yet should be regarded as relatives of neurons on the basis of their structure, function, and metabolism. Many of the studies carried out in the past to understand the secretory process have employed perfused adrenal glands. Although this technique has provided very useful information regarding secretion, it did not allow the study of the cellular events involved in the secretory process. To obtain further information on cell secretion, several laboratories including our own have published methods for the isolation and culture of chromaffin cells. The cultured chromaffin cells have shown themselves to be one of the most useful systems developed for the study of the neuroendocrine functions of paraneurons. Studies on cultured chromaffin cells have provided important information on secretory cell cytoskeleton: a group of proteins, some of them previously known from studies on muscle, which form a cytoplasmic network in all non-muscle cells including secretory cells. Immunohistochemical studies have shown at least three types of filament systems: microfilaments, microtubules, and intermediate filaments. In addition, a large variety of cytoskeleton-associated proteins have been characterized. Chromaffin cells are among those non-muscle cells from which cytoskeleton proteins have been isolated and characterized. Owing to similarities between "stimulus–secretion coupling" and "excitation–contraction coupling" in muscle, it has been proposed that the secretory process might be mediated by contractile elements either associated with secretory vesicles or present elsewhere in the secretory cell. Cytoskeletal proteins (actin, myosin, α-actinin, fodrin, tubulin, and neurofilament subunits) and their regulatory proteins (calmodulin, gelsolin) have been isolated from chromaffin cells and characterized. Their physicochemical proteins have been studied and their cellular localizations have been revealed by biochemical, immunocytochemical, and ultrastructural techniques. α-Actinin and fodrin are components of chromaffin granule membranes and some of the cell actin co-purified with secretory granules. Actin forms a network of microfilaments in the subplasmalemma region. This network of filaments is cross-linked and stabilized by several proteins as well as secretory vesicles. Gelsolin, a Ca2+-dependent actin filament severing protein seems to control the length of the actin filaments, thus playing an important role in the regulation of cytoplasm viscosity. Calmodulin also seems to be involved in secretion. Trifluoperazine, a calmodulin antagonist, blocks stimulation-induced hormone release from chromaffin cells at a step distal from calcium entry. High affinity calmodulin binding sites are present in chromaffin granule membranes, and the calmodulin binding proteins of these membranes have been characterized. Furthermore, microinjection of calmodulin antibodies into chromaffin cells blocks hormone output in response to cell stimulation. In view of the above findings, the possible roles of contractile proteins and calmodulin in cell secretion are discussed.Key words: secretion, cytoskeleton, paraneuron, calmodulin, cytosol viscosity.

scholarly journals Secretory cell actin-binding proteins: identification of a gelsolin-like protein in chromaffin cells.

1986 ◽  
Vol 102 (2) ◽  
pp. 636-646 ◽  
Author(s):  
M F Bader ◽  
J M Trifaró ◽  
O K Langley ◽  
D Thiersé ◽  
D Aunis
Keyword(s):  
Adrenal Medulla ◽  
Chromaffin Cells ◽  
Binding Proteins ◽  
Binding Protein ◽  
Actin Binding ◽  
Secretory Process ◽  
Secretory Cells ◽  
Breakdown Product ◽  
Actin Binding Proteins ◽  
Actin Binding Protein

Chromaffin cells, secretory cells of the adrenal medulla, have been shown to contain actin and other contractile proteins, which might be involved in the secretory process. Actin and Ca++-sensitive actin-binding proteins were purified from bovine adrenal medulla on affinity columns using DNase-I as a ligand. Buffers that contained decreasing Ca++ concentrations were used to elute three major proteins of 93, 91, and 85 kD. The bulk of the actin was eluted with guanidine-HCl buffer plus some 93- and 91-kD proteins. These Ca++-sensitive regulatory proteins were shown to inhibit the gelation of actin using the low-shear falling ball viscometer and by electron microscopy. Actin filaments were found to be shortened by fragmentation. Using antibody raised against rabbit lung macrophage gelsolin, proteolytic digestion with Staphylococcus V8 protease and two-dimensional gel electrophoresis, the 91-kD actin-binding protein was shown to be a gelsolin-like protein. The 93-kD actin-binding protein also showed cross-reactivity with anti-gelsolin antibody, similar peptide maps, and a basic-shift in pHi indicating that this 93-kD protein is a brevin-like protein, derived from blood present abundantly in adrenal medulla. Purification from isolated chromaffin cells demonstrated the presence of 91- and 85-kD proteins, whereas the 93-kD protein was hardly detectable. The 85-kD protein is not a breakdown product of brevin-like or gelsolin-like proteins. It did not cross-react with anti-gelsolin antibody and showed a very different peptide map after mild digestion with V8 protease. Antibodies were raised against the 93- and 91-kD actin-binding proteins and the 85-kD actin-binding protein. Antibody against the 85-kD protein did not cross-react with 93- and 91-kD proteins and vice versa. In vivo, the cytoskeleton organization of chromaffin secretory cells is not known, but appears to be under the control of the intracellular concentration of free calcium. The ability of calcium to activate the gelsolin-like protein, and as shown elsewhere to alter fodrin localization, provides a mechanism for gel-sol transition that might be essential for granule movement and membrane-membrane interactions involved in the secretory process.

Chromaffin cell cytoskeleton: its possible role in secretion

1985 ◽  
Vol 63 (6) ◽  
pp. 661-679 ◽  
Author(s):  
J.-M. Trifaró ◽  
M.-F. Bader ◽  
J.-P. Doucet
Keyword(s):  
Chromaffin Cells ◽  
Chromaffin Cell ◽  
Secretory Granules ◽  
Regulatory Proteins ◽  
Hormone Release ◽  
Chromaffin Granule ◽  
Calmodulin Antagonist ◽  
Calmodulin Binding ◽  
Cell Functions ◽  
Adrenal Chromaffin

Cytoskeleton proteins (actin, myosin, α-actinin, spectrin, tubulin, neurofilament subunits) and their regulatory proteins (calmodulin, gelsolin) have been isolated from adrenal chromaffin cells and characterized. Their physicochemical properties have been studied and their cell localizations have been revealed by biochemical, immunocytochemical, and ulstrastructural techniques. α-Actinin and spectrin are components of chromaffin granule membranes and some of the cell actin copurifies with these secretory granules. Myosin is not detected in the granules, but is present mainly in the cytosol and close to the cell surface. Trifluoperazine, a calmodulin antagonist, blocks stimulation-induced hormone release from chromaffin cells at a step distal from Ca2+ entry. High affinity calmodulin-binding sites have also been found in chromaffin granule membranes and their calmodulin-binding proteins have been characterized. Furthermore, microinjection of calmodulin antibodies into chromaffin cells blocks hormone output in response to stimulation. In view of the above findings, the possible roles of contractile proteins and calmodulin in chromaffin cell functions are discussed.

Adrenal paraneurone contractile proteins and stimulus–secretion coupling

1984 ◽  
Vol 62 (5) ◽  
pp. 493-501 ◽  
Author(s):  
J. M. Trifaró ◽  
R. L. Kenigsberg ◽  
A. Côté ◽  
R. W. H. Lee ◽  
T. Hikita
Keyword(s):  
Chromaffin Cells ◽  
Secretory Granules ◽  
Contractile Proteins ◽  
Chromaffin Granule ◽  
Calmodulin Antagonist ◽  
Calmodulin Binding ◽  
Cell Functions ◽  
Cell Localization ◽  
Stimulus Secretion Coupling ◽  
Adrenal Chromaffin

Actin, myosin, and alpha-actinin have been isolated from adrenal chromaffin cells and characterized. Their physicochemical properties have been studied and their cell localization revealed by biochemical, immunocytochemical, and ultrastructural techniques. Alpha-actinin is a component of chromaffin granule membranes and some of the cell actin copurifies with these secretory granules. Myosin is not detected in the granules but is present mainly in the cytosol. Trifluoperazine, a calmodulin antagonist, blocks stimulation-induced hormone release from chromaffin cells at a step distal from Ca2+ entry. High affinity calmodulin binding sites have also been found in chromaffin granule membranes. Furthermore, microinjection of calmodulin antibodies into chromaffin cells blocks hormone output in response to stimulation. In view of the above findings, the possible roles of contractile proteins and calmodulin in chromaffin cell functions is discussed.

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

The cytoskeleton as a barrier to exocytosis in secretory cells

1988 ◽  
Vol 139 (1) ◽  
pp. 253-266 ◽  
Author(s):  
D. Aunis ◽  
M. F. Bader
Keyword(s):  
Chromaffin Cells ◽  
Binding Proteins ◽  
Secretory Granules ◽  
Actin Binding ◽  
Bacterial Toxin ◽  
Secretory Cells ◽  
Free Access ◽  
Actin Binding Proteins ◽  
Permeabilized Cells ◽  
Cytoskeletal Network

Chromaffin cells of the adrenal medulla synthesize, store and secrete catecholamines. These cells contain numerous electron-dense secretory granules which discharge their contents into the extracellular space by exocytosis. The subplasmalemmal area of the chromaffin cell is characterized by the presence of a highly organized cytoskeletal network. F-Actin seems to be exclusively localized in this area and together with specific actin-binding proteins forms a dense viscoelastic gel; fodrin, vinculin and caldesmon, three actin cross-linking proteins, and gelsolin, an actin-severing protein, are found in this subplasmalemmal region. Since fodrin-, caldesmon- and alpha-actinin-binding sites exist on secretory granule membranes, actin filaments can also link secretory granules. Chromaffin granules can be entrapped in this subplasmalemmal lattice and thus the cytoskeleton acts as a barrier preventing exocytosis. When cells are stimulated, molecular rearrangements of the subplasmalemmal cytoskeleton take place: F-actin depolymerizes and fodrin reorganizes into patches. In addition, introduction of monospecific antifodrin immunoglobulins into digitonin-permeabilized cells blocks exocytosis, demonstrating the crucial role of this actin-binding protein. In bacterial toxin-permeabilized chromaffin cells, experiments using actin-perturbing agents such as cytochalasin D and DNAase I suggest that exocytosis is in part controlled by the cytoskeleton. The intracellular signal governing the cytoskeletal reorganization (associated with exocytosis) is calcium. Calcium inhibits some and activates other actin-binding proteins and consequently causes dissolution of the subplasmalemmal cytoskeleton. This dissolution of cytoskeletal filaments should result in granule detachment and permit granules free access to exocytotic sites on the plasma membrane.

scholarly journals LYSOSOME FUNCTION IN THE REGULATION OF THE SECRETORY PROCESS IN CELLS OF THE ANTERIOR PITUITARY GLAND

1966 ◽  
Vol 31 (2) ◽  
pp. 319-347 ◽  
Author(s):  
Robert E. Smith ◽  
Marilyn G. Farquhar
Keyword(s):  
Anterior Pituitary ◽  
Dense Body ◽  
Secretory Granules ◽  
Secretory Process ◽  
Secretory Cells ◽  
Residual Body ◽  
Multivesicular Bodies ◽  
Dense Bodies ◽  
Pituitary Glands ◽  
Secretory Products

The nature and content of lytic bodies and the localization of acid phosphatase (AcPase) activity were investigated in mammotrophic hormone-producing cells (MT) from rat anterior pituitary glands. MT were examined from lactating rats in which secretion of MTH1 was high and from postlactating rats in which MTH secretion was suppressed by removing the suckling young. MT from lactating animals contained abundant stacks of rough-surfaced ER, a large Golgi complex with many forming secretory granules, and a few lytic bodies, primarily multivesicular bodies and dense bodies. MT from postlactating animals, sacrificed at selected intervals up to 96 hr after separation from their suckling young, showed (a) progressive involution of the protein synthetic apparatus with sequestration of ER and ribosomes in autophagic vacuoles, and (b) incorporation of secretory granules into multivesicular and dense bodies. The content of mature granules typically was incorporated into dense bodies whereas that of immature granules found its way preferentially into multivesicular bodies. The secretory granules and cytoplasmic constituents segregated within lytic bodies were progressively degraded over a period of 24 to 72 hr to yield a common residual body, the vacuolated dense body. In MT from lactating animals, AcPase reaction product was found in lytic bodies, and in several other sites not usually considered to be lysosomal in nature, i.e., inner Golgi cisterna and associated vesicles, and around most of the immature, and some of the mature secretory granules. In MT from postlactating animals, AcPase was concentrated in lytic bodies; reaction product and incorporated secretory granules were frequently recognizable within the same multivesicular or dense body which could therefore be identified as "autolysosomes" connected with the digestion of endogenous materials. Several possible explanations for the occurrence of AcPase in nonlysosomal sites are discussed. From the findings it is concluded that, in secretory cells, lysosomes function in the regulation of the secretory process by providing a mechanism which takes care of overproduction of secretory products.

scholarly journals Targeted Ablation of the Chromogranin A (Chga) Gene: Normal Neuroendocrine Dense-Core Secretory Granules and Increased Expression of Other Granins

2006 ◽  
Vol 20 (8) ◽  
pp. 1935-1947 ◽  
Author(s):  
Geoffrey N. Hendy ◽  
Tong Li ◽  
Martine Girard ◽  
Richard C. Feldstein ◽  
Shree Mulay ◽  
...  
Keyword(s):  
Secretory Granule ◽  
Chromogranin A ◽  
Chromaffin Cells ◽  
Secretory Granules ◽  
Hormone Secretion ◽  
Proteolytic Processing ◽  
Dense Core ◽  
Secretory Process ◽  
Chromogranin B ◽  
Developmental Abnormalities

Abstract Chromogranin A (CgA), originally identified in adrenal chromaffin cells, is a member of the granin family of acidic secretory glycoproteins that are expressed in endocrine cells and neurons. CgA has been proposed to play multiple roles in the secretory process. Intracellularly, CgA may control secretory granule biogenesis and target neurotransmitters and peptide hormones to granules of the regulated pathway. Extracellularly, peptides formed as a result of proteolytic processing of CgA may regulate hormone secretion. To investigate the role of CgA in the whole animal, we created a mouse mutant null for the Chga gene. These mice are viable and fertile and have no obvious developmental abnormalities, and their neural and endocrine functions are not grossly impaired. Their adrenal glands were structurally unremarkable, and morphometric analyses of chromaffin cells showed vesicle size and number to be normal. However, the excretion of epinephrine, norepinephrine, and dopamine was significantly elevated in the Chga null mutants. Adrenal medullary mRNA and protein levels of other dense-core secretory granule proteins including chromogranin B, and secretogranins II to VI were up-regulated 2- to 3-fold in the Chga null mutant mice. Hence, the increased expression of the other granin family members is likely to compensate for the Chga deficiency.

Rab3 is present on endosomes from bovine chromaffin cells in primary culture

1999 ◽  
Vol 112 (5) ◽  
pp. 641-649
Author(s):  
D. Slembrouck ◽  
W.G. Annaert ◽  
J.M. Wang ◽  
W.P. Potter
Keyword(s):  
Primary Culture ◽  
Chromaffin Cells ◽  
Secretory Granules ◽  
Regulatory Function ◽  
Secretory Vesicles ◽  
Granule Formation ◽  
Subcellular Compartment ◽  
Starting Point ◽  
Bovine Chromaffin Cells ◽  
Vesicle Cycle

Rab3a, a small GTP-binding protein, is believed to mediate Ca2+-dependent exocytosis. Consistent with such a role was the previously reported specific association of Rab3a with synaptic vesicles in neurons and secretory granules in adrenal chromaffin cells. Secretory vesicles are believed to be the final point of Rab3a membrane association, as it was shown by several groups that Rab3a dissociates from the secretory vesicle membrane during stimulated exocytosis. In chromaffin cells, Rab3a is not exclusively localized on secretory granules since a fraction is present on a previously unidentified subcellular compartment equilibrating at light sucrose density. This ‘light’ membraneous structure could be the starting point for reassociation of Rab3a with membranes involved in granule formation, or it could be a structure unrelated to granules. The present study used several subcellular fractionation techniques and immunomicroscopy to unravel the nature of the ‘light’ Rab3a-containing structures from bovine chromaffin cells in primary culture. After stimulation, amounts of both Rab3a-d and the granule marker dopamine-beta-hydroxylase (DbetaH) increase transiently in sucrose gradient fractions enriched in endosomal markers. A diaminobenzidine-induced density shift of endosomes alters the distribution of DbetaH and Rab3a-d. At the ultrastructural level, subplasmalemmal pleiomorphic organelles were detected by Rab3a-d-immunogold labelling. Taken together our data provide for the first time evidence that internalised secretory granule membranes go through an endosomal stage where Rab3a is present, resembling the neuronal synaptic vesicle cycle. This indicates that the endosome is an important trafficking route in the biogenesis/recycling of secretory vesicles in chromaffin cells, in which Rab3a could have an as yet unknown regulatory function, and could point to the existence of alternative recycling pathways for the chromaffin granule membrane.

Molecular Machinery and Mechanism of Cell Secretion

2005 ◽  
Vol 230 (5) ◽  
pp. 307-319 ◽  
Author(s):  
Bhanu P. Jena
Keyword(s):  
Lipid Membrane ◽  
Secretory Vesicle ◽  
Secretory Process ◽  
Secretory Vesicles ◽  
Cell Secretion ◽  
Vesicle Membrane ◽  
Cellular Processes ◽  
Molecular Machinery ◽  
Secretory Products ◽  
First Time

Secretion occurs in all living cells and involves the delivery of intracellular products to the cell exterior. Secretory products are Packaged and stored in membranous sacs or vesicles within the cell. When the cell needs to secrete these products, the secretory vesicles containing them dock and fuse at plasma membrane-associated supramolecular structures, called poro-somes, to release their contents. Specialized cells for neurotransmission, enzyme secretion, or hormone release use a highly regulated secretory process. Similar to other fundamen-tal cellular processes, cell secretion is precisely regulated. During secretion, swelling of secretory vesicles results in a build-up of intravesicular pressure, allowing expulsion of vesicular contents. The extent of vesicle swelling dictates the amount of vesicular contents expelled. The discovery of the Porosome as the universal secretory machinery, its isolation, its structure and dynamics at nanometer resolution and in real time, and its biochemical composition and functional reconstitution into artificial lipid membrane have been determined. The Molecular mechanism of secretory vesicle swelling and the fusion of opposing bilayers, that is, the fusion of secretory vesicle membrane at the base of the porosome membrane, have also been resolved. These findings reveal, for the first time, the universal molecular machinery and mechanism of secretion in cells.

scholarly journals Glycosylation and transmembrane topography of bovine chromaffin granule p65

1991 ◽  
Vol 279 (3) ◽  
pp. 699-703 ◽  
Author(s):  
H B Tugal ◽  
F van Leeuwen ◽  
D K Apps ◽  
J Haywood ◽  
J H Phillips
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibody ◽  
Synaptic Vesicles ◽  
Secretory Granules ◽  
Chromaffin Granules ◽  
Trypsin Treatment ◽  
Chromaffin Granule ◽  
Calmodulin Binding ◽  
N Terminus ◽  
Adrenal Chromaffin

The bovine homologue of p65, a calmodulin-binding protein located in the membranes of synaptic vesicles and endocrine secretory granules, has been studied by the use of monoclonal antibodies directed against this antigen and against dopamine beta-mono-oxygenase. The protein (apparent molecular mass 67 kDa; pI = 5.5-6.2) is partially degraded by treatment with neuraminidase or endoglycosidase F. Trypsin treatment of intact adrenal chromaffin granules or of granule membranes releases a soluble 39 kDa fragment of p65 which corresponds to the whole of its cytoplasmic domain. This domain contains both the epitope for the monoclonal antibody cgm67 and the calmodulin-binding site. The 20 amino acids at the N-terminus of this fragment are identical to part of the rat p65 sequence.

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