scholarly journals MODULATION IN NUCLEOSIDE DIPHOSPHATASE ACTIVITY OF MAMMOTROPHIC CELLS OF THE RAT ADENOHYPOPHYSIS DURING SECRETION

1970 ◽  
Vol 18 (4) ◽  
pp. 237-250 ◽  
Author(s):  
ROBERT E. SMITH ◽  
MARILYN G. FARQUHAR
Keyword(s):  
Golgi Apparatus ◽  
Protein Secretion ◽  
Outer Surface ◽  
Secretory Granules ◽  
Hormone Secretion ◽  
Staining Intensity ◽  
Female Rat ◽  
Intercellular Spaces ◽  
Secretion Granules ◽  
Nucleoside Diphosphatase

The modulations in nucleoside diphosphatase (NDPase) activity which occur during protein secretion have been investigated in mammotrophic hormone-producing cells (MT) of the female rat adenohypophysis. Pituitaries were fixed by perfusion or immersion in glutaraldehyde, and nonfrozen sections were incubated for NDPase. Tissue was examined from lactating and estrogen-treated animals in which mammotrophic hormone secretion (MTH) is high and from postlactating rats in which secretion of MTH is suppressed. In all experimental groups, NDPase reaction product was found: ( a) in Golgi cisternae, ( b) around forming and mature secretion granules, ( c) in pericapillary and intercellular spaces and ( d) along the outer surface of endothelial and MT cell membranes. The staining intensity of both the intracellular and extracellular sites paralleled the level of MTH secretion; it was greatest after estrogen treatment, moderate during lactation and minimal in the postlactating animal. In animals given estrogen, the Golgi apparatus was increased in size and up to six successive cisternae along the concave Golgi face were filled with reaction product in virtually every cell. In postlactating animals, the Golgi apparatus was small, and there was only patchy staining of a few cisternae in some cells. From its location and fluctuations with secretion, it seems likely that NDPase activity may be associated with the condensation and/or discharge of secretory granules.

Three dimensional configuration of the secretory pathway and segregation of secretion granules in the yeast Saccharomyces cerevisiae

2001 ◽  
Vol 114 (12) ◽  
pp. 2231-2239 ◽  
Author(s):  
Alain Rambourg ◽  
Catherine L. Jackson ◽  
Yves Clermont
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Golgi Apparatus ◽  
Mammalian Cells ◽  
Secretory Pathway ◽  
Secretory Granules ◽  
Staining Intensity ◽  
Permissive Temperature ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Secretion Granules

The structural elements of the secretory pathway in the budding yeast Saccharomyces cerevisiae were analyzed by 3D stereo-electron microscopy using relatively thick sections in which membranes were selectively impregnated. In a wild-type strain, tubular networks of various sizes and staining properties were distributed throughout the cytoplasm. As a rule, wide-meshed, lightly stained polygonal networks were connected to more or less fenestrated sheets of endoplasmic reticulum (ER). Some of these networks were continuous with more intensely stained networks and narrower meshes that displayed at their intersections nodular dilations that progressively increased in size and staining properties to reach those of secretion granules. Such networks presumably corresponded to Golgi elements. Indeed, stacked cisternae typical of the mammalian Golgi apparatus are rarely found in wild-type cells. However, if it is assumed that the Golgi apparatus plays a key role in the segregation and maturation of secretion granules, then tubular networks with nodular dilations should be equivalent to parts of this organelle. In correlation with the increase in size and density of the nodules there was a decrease in diameter and staining intensity of the interconnecting tubules. These results parallel observations on the formation of secretory granules in mammalian cells and suggest that the segregation of secretory material is concomitant with the progressive perforation and tubulization of previously unperforated sheets. When the sec21-3 thermosensitive mutant was examined at the nonpermissive temperature (37°C), the secretory pathway was blocked at exit from the ER, which started to accumulate as clusters of narrow, anastomosed, unperforated ribbon-like elements. When the block was released by shifting down to permissive temperature (24°C), tubular networks of various sizes and caliber, presumably Golgi in nature, formed as soon as 5 minutes after release of the block. At later time intervals, granules of various sizes and densities appeared to be released by rupture of these tubular networks or even to form at the edges of ER fenestrae. These observations support a dynamic maturation process in which the formation of secretion granules occurs by means of an oriented series of membrane transformations starting at the ER and culminating with the liberation of secretion granules from Golgi networks.

scholarly journals THE ELABORATION OF PROTEIN AND CARBOHYDRATE BY RAT PARATHYROID CELLS AS REVEALED BY ELECTRON MICROSCOPE RADIOAUTOGRAPHY

1971 ◽  
Vol 51 (3) ◽  
pp. 596-610 ◽  
Author(s):  
K. Nakagami ◽  
H. Warshawsky ◽  
C. P. Leblond
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Intravenous Injection ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Glycoprotein Precursor ◽  
Secretion Granules ◽  
And Migration ◽  
The One ◽  
Membrane Cell

The parathyroid glands of young rats were radioautographed after a single injection of the protein precursor tyrosine-3H in the hope of identifying the sites of synthesis and migration of newly formed protein in the gland cells. The same procedure was used after injection of the glycoprotein precursor galactose-3H. As early as 2 min after intravenous injection of tyrosine-3H, the label was mainly found in the rough endoplasmic reticulum suggesting that cisternal ribosomes are sites of protein synthesis. By 5 and 10 min, much of the label had migrated from the rough endoplasmic reticulum into the Golgi apparatus. By 20 and 30 min, some label had migrated from there into secretory granules. By 45 min and 1 hr, the label content of the cell had decreased, indicating release of labeled material outside the cell. At 2 min after intravenous injection of galactose-3H, the label was mainly present in the Golgi apparatus, where presumably galactose is taken up into glycoprotein. By 10 min, some label appeared in secretion granules and by 30 min release of the material to the outside of the cell was under way. In conclusion, it is likely that the tyrosine-labeled protein material consists mainly of the parathyroid hormone. The galactose-labeled carbohydrate material would be either associated with the hormone in the cell or be part of a distinct glycoprotein which may be the one present on the outer surface of the plasma membrane (cell coat).

scholarly journals The intracellular pathway of vitellogenin secretion in the frog hepatocyte as revealed by protein A-gold immunocytochemistry.

1984 ◽  
Vol 32 (7) ◽  
pp. 697-704 ◽  
Author(s):  
G H Herbener ◽  
M Bendayan ◽  
R C Feldhoff
Keyword(s):  
Golgi Apparatus ◽  
Protein Secretion ◽  
Secretory Pathway ◽  
Rana Catesbeiana ◽  
Secretory Granules ◽  
Plasma Concentrations ◽  
Protein A ◽  
Secretory Cells ◽  
Vitellogenin Synthesis ◽  
Cellular Compartments

The protein A-gold immunocytochemical technique was applied to the localization of vitellogenin in the hepatocyte of the bullfrog, Rana catesbeiana, eight days after treatment with estradiol-17 beta. Specific labeling was present in cellular compartments involved in protein secretion and was shown to progress in sequence through RER, Golgi apparatus, immature secretory granules, and mature secretory granules. Labeling intensities were quantitated and the values ranged from 34.6 to 172 gold particles/micron 2. In contrast, low background labeling was observed over mitochondria, nuclei, lipid droplets, and bile canaliculi. These observations support the hypothesis that vitellogenin synthesis and secretion in the frog hepatocyte lies exclusively along the RER-Golgi-granule secretory pathway. In addition to the cellular compartments involved in protein secretion, labeling was found over the majority of the lysosomes. The intensity of lysosomal labeling was intermediate between that of RER and Golgi apparatus. This labeling of lysosomes may be a consequence of the high blood plasma concentrations of vitellogenin that occur in the frog model, or to the well-known crinophagy phenomenon present in secretory cells.

POSSIBLE ROLE OF 5α-ANDROSTANE-3α,17β-DIOL IN THE CONTROL OF FOLLICLE-STIMULATING HORMONE SECRETION IN THE IMMATURE FEMALE RAT

1982 ◽  
Vol 92 (1) ◽  
pp. 37-42 ◽  
Author(s):  
H. M. A. MEIJS-ROELOFS ◽  
P. KRAMER ◽  
L. GRIBLING-HEGGE
Keyword(s):  
Inhibitory Action ◽  
Combined Treatment ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Immature Rat ◽  
Rat Strain ◽  
Intact Rats

A possible role of 5α-androstane-3α,17β-diol (3α-androstanediol) in the control of FSH secretion was studied at various ages in ovariectomized rats. In the rat strain used, vaginal opening, coincident with first ovulation, generally occurs between 37 and 42 days of age. If 3α-androstanediol alone was given as an ovarian substitute, an inhibitory effect on FSH release was evident with all three doses tested (50, 100, 300 μg/100 g body wt) between 13 and 30 days of age; at 33–35 days of age only the 300 μg dose caused some inhibition of FSH release. Results were more complex if 3α-androstanediol was given in combined treatment with oestradiol and progesterone. Given with progesterone, 3α-androstanediol showed a synergistic inhibitory action on FSH release between 20 and 30 days of age. However, when 3α-androstanediol was combined with oestradiol a clear decrease in effect, as compared to the effect of oestradiol alone, was found between 20 and 30 days of age. Also the effect of combined oestradiol and progesterone treatment was greater than the effect of combined treatment with oestradiol, progesterone and 3α-androstanediol. At all ages after day 20 none of the steroid combinations tested was capable of maintaining FSH levels in ovariectomized rats similar to those in intact rats. It is concluded that 3α-androstanediol might play a role in the control of FSH secretion in the immature rat, but after day 20 the potentially inhibitory action of 3α-androstanediol on FSH secretion is limited in the presence of oestradiol.

scholarly journals SYNTHESIS, MIGRATION, AND RELEASE OF PRECURSOR COLLAGEN BY ODONTOBLASTS AS VISUALIZED BY RADIOAUTOGRAPHY AFTER [3H]PROLINE ADMINISTRATION

1974 ◽  
Vol 60 (1) ◽  
pp. 92-127 ◽  
Author(s):  
Melvyn Weinstock ◽  
C. P. Leblond
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Phosphotungstic Acid ◽  
Secretory Granules ◽  
Low Ph ◽  
Collagen Fibrils ◽  
Dentin Collagen ◽  
Odontoblast Process ◽  
High Radioactivity

The elaboration of dentin collagen precursors by the odontoblasts in the incisor teeth of 30–40-g rats was investigated by electron microscopy, histochemistry, and radioautography after intravenous injection of tritium-labeled proline. At 2 min after injection, when the labeling of blood proline was high, radioactivity was restricted to the rough endoplasmic reticulum, indicating that it is the site of synthesis of the polypeptide precursors of collagen, the pro-alpha chains. At 10 min, when the labeling of blood proline had already declined, radioactivity was observed in spherical portions of Golgi saccules containing entangled threads, and, at 20 min, radioactivity appeared in cylindrical portions containing aggregates of parallel threads. The parallel threads measured 280–350 nm in length and stained with the low pH-phosphotungstic acid technique for carbohydrate and with the silver methenamine technique for aldehydes (as did extracellular collagen fibrils). The passage of label from spherical to cylindrical Golgi portions is associated with the reorganization of entangled into parallel threads, which is interpreted as the packing of procollagen molecules. Between 20 and 30 min, prosecretory and secretory granules respectively became labeled. These results indicate that the cylindrical portions of Golgi saccules transform into prosecretory and subsequently into secretory granules. Within these granules, the parallel threads, believed to be procollagen molecules, are transported to the odontoblast process. At 90 min and 4 h after injection, label was present in predentin, indicating that the labeled content of secretory granules had been released into predentin. This occurred by exocytosis as evidenced by the presence of secretory granules in fusion with the plasmalemma of the odontoblast process. It is proposed that pro-alpha chains give rise to procollagen molecules which assemble into parallel aggregates in the Golgi apparatus. Procollagen molecules are then transported within secretory granules to the odontoblast process and released by exocytosis. In predentin procollagen molecules would give rise to tropocollagen molecules, which would then polymerize into collagen fibrils.

scholarly journals INDUCTION OF ENDOMETRIAL PEROXIDASE SYNTHESIS AND SECRETION BY ESTROGEN AND ESTROGEN ANTAGONIST

1974 ◽  
Vol 62 (2) ◽  
pp. 449-459 ◽  
Author(s):  
Andrew Churg ◽  
Winston A. Anderson
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Peroxidase Activity ◽  
Secretory Granules ◽  
Combined Treatment ◽  
Initial Injection ◽  
Immature Rats ◽  
Glandular Cells ◽  
Endogenous Peroxidase ◽  
Estrogen Antagonist

Synthesis of peroxidase was induced in the uterine epithelium of immature rats by multiple doses over a 24–96-h period of either 17 ß-estradiol, the estrogen-antagonist Parke-Davis CI-628, or a combination of estradiol plus antagonist. Endogenous peroxidase activity first appeared in the cisternae of the rough endoplasmic reticulum of surface epithelial and glandular cells within 24–48 after the initial injection. Uterine peroxidase activity was also visible in the cisternae of the Golgi apparatus, in Golgi-derived secretory granules, and within the uterine and glandular lumen. Some cells of the epithelium produced little or no peroxidase, even after 96 h. Whereas the antagonist appeared to induce synthesis and secretion of peroxidase, neither the antagonist alone nor the combined treatment (estradiol plus antagonist) reproduced the estradiol-mediated growth in organ size and increased lumen diameter.

scholarly journals MyRIP interaction with MyoVa on secretory granules is controlled by the cAMP-PKA pathway

2012 ◽  
Vol 23 (22) ◽  
pp. 4444-4455 ◽  
Author(s):  
Flora Brozzi ◽  
Sophie Lajus ◽  
Frederique Diraison ◽  
Shavanthi Rajatileka ◽  
Katy Hayward ◽  
...  
Keyword(s):  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Secretory Granules ◽  
Hormone Secretion ◽  
Motor Protein ◽  
Functional Protein ◽  
Interacting Protein ◽  
Myosin Va ◽  
Glucose Stimulated Insulin Secretion

Myosin- and Rab-interacting protein (MyRIP), which belongs to the protein kinase A (PKA)–anchoring family, is implicated in hormone secretion. However, its mechanism of action is not fully elucidated. Here we investigate the role of MyRIP in myosin Va (MyoVa)-dependent secretory granule (SG) transport and secretion in pancreatic beta cells. These cells solely express the brain isoform of MyoVa (BR-MyoVa), which is a key motor protein in SG transport. In vitro pull-down, coimmunoprecipitation, and colocalization studies revealed that MyRIP does not interact with BR-MyoVa in glucose-stimulated pancreatic beta cells, suggesting that, contrary to previous notions, MyRIP does not link this motor protein to SGs. Glucose-stimulated insulin secretion is augmented by incretin hormones, which increase cAMP levels and leads to MyRIP phosphorylation, its interaction with BR-MyoVa, and phosphorylation of the BR-MyoVa receptor rabphilin-3A (Rph-3A). Rph-3A phosphorylation on Ser-234 was inhibited by small interfering RNA knockdown of MyRIP, which also reduced cAMP-mediated hormone secretion. Demonstrating the importance of this phosphorylation, nonphosphorylatable and phosphomimic Rph-3A mutants significantly altered hormone release when PKA was activated. These data suggest that MyRIP only forms a functional protein complex with BR-MyoVa on SGs when cAMP is elevated and under this condition facilitates phosphorylation of SG-associated proteins, which in turn can enhance secretion.

scholarly journals ELECTRON MICROSCOPIC STUDY OF THE ADRENOCORTICOTROPIN-PRODUCING CELL WITH THE USE OF UNLABELED ANTIBODY AND THE SOLUBLE PEROXIDASE-ANTIPEROXIDASE COMPLEX

1972 ◽  
Vol 20 (8) ◽  
pp. 590-603 ◽  
Author(s):  
G. C. MORIARTY ◽  
N. S. HALMI
Keyword(s):  
Secretory Granules ◽  
Staining Intensity ◽  
Electron Microscopic ◽  
Early Effect ◽  
Acth Cell ◽  
Maximal Diameter ◽  
Soluble Peroxidase ◽  
Ultrathin Sections ◽  
Acth Secreting ◽  
Unlabeled Antibody

The technique involving use of unlabeled antibody and the peroxidase-antiperoxidase complex was used to identify the adrenocorticotropin (ACTH)-secreting cell in the anterior pituitary lobe of the rat and to localize ACTH in it electron microscopically in ultrathin sections. The ACTH cell is star-shaped, with processes extending around other cells, and contains secretory granules of a maximal diameter of 300 mµ arranged peripherally along the plasma membrane. Stain was observed on secretory granules, around them, in the Golgi complex and in rough endoplasmic reticulum. One day after adrenalectomy, the ACTH cell is degranulated and the staining intensity of its remaining granules and cytoplasm is decreased, suggesting release of ACTH stores. If cortisol is given 6 hr after adrenalectomy, 18 hr later the ACTH cells are well granulated and the granules stain more intensely than normal. In addition, staining around the granules and throughout the cytoplasm is more intense, suggesting that an early effect of cortisol is to block release of ACTH. Twenty-one days after adrenalectomy, the ACTH cells are greatly increased in numbers and have complex, tortuous processes filled with intensely stained secretory granules.

scholarly journals Brefeldin A inhibits transport of the glycophorin-binding protein from Plasmodium falciparum into the host erythrocyte

1994 ◽  
Vol 300 (3) ◽  
pp. 821-826 ◽  
Author(s):  
J Benting ◽  
D Mattei ◽  
K Lingelbach
Keyword(s):  
Plasmodium Falciparum ◽  
Golgi Apparatus ◽  
Host Cell ◽  
Protein Secretion ◽  
Secretory Pathway ◽  
Binding Protein ◽  
Brefeldin A ◽  
Cell Cytoplasm ◽  
Parasite Cell ◽  
Host Cell Cytoplasm

Plasmodium falciparum, a protozoan parasite of the human erythrocyte, causes the most severe form of malaria. During its intraerythrocytic development, the parasite synthesizes proteins which are exported into the host cell. The compartments involved in the secretory pathway of P. falciparum are still poorly characterized. A Golgi apparatus has not been identified, owing to the lack of specific protein markers and Golgi-specific post-translational modifications in the parasite. The fungal metabolite brefeldin A (BFA) is known to inhibit protein secretion in higher eukaryotes by disrupting the integrity of the Golgi apparatus. We have used the parasite-encoded glycophorin-binding protein (GBP), a soluble protein found in the host cell cytoplasm, as a marker to investigate the effects of BFA on protein secretion in the intracellular parasite. In the presence of BFA, GBP was not transported into the erythrocyte, but remained inside the parasite cell. The effect caused by BFA was reversible, and the protein could be chased into the host cell cytoplasm within 30 min. Transport of GBP from the BFA-sensitive site into the host cell did not require protein synthesis. Similar observations were made when infected erythrocytes were incubated at 15 degrees C. Incubation at 20 degrees C resulted in a reduction rather than a complete block of protein export. The relevance of our findings to the identification of compartments involved in protein secretion from the parasite cell is discussed.

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