scholarly journals Microtubule assembly in cultivated Greene melanoma cells is stimulated by dibutyryl adenosine 3':5'-cyclic monophosphate or cholera toxin.

1976 ◽  
Vol 71 (3) ◽  
pp. 735-748 ◽  
Author(s):  
A M DiPasquale ◽  
J McGuire ◽  
G Moellmann ◽  
S J Wasserman
Keyword(s):  
Cyclic Amp ◽  
Cholera Toxin ◽  
Gel Electrophoresis ◽  
Unit Area ◽  
Melanoma Cells ◽  
Microtubule Assembly ◽  
Dibutyryl Cyclic Amp ◽  
Cyclic Monophosphate ◽  
Cell Processes ◽  
Hamster Melanoma

Both dibutyryl cyclic AMP (DBcAMP) and cholera toxin promote the formation and elongation of processes of cultivated Greene hamster melanoma cells. The formation and maintenance of these processes, which contain many microtubules, are sensitive to colcemid and vinblastine. Tubulin was measured by [3H]colchicine binding and by acrylamide gel electrophoresis. We found that DBcAMP or cholera toxin increases the ratio of polymerized to unpolymerized tubulin but not the total amount of tubulin per cell. The sum of the lengths of microtubules per unit area was significantly greater in cells treated with DBcAMP than in control cells. Our findings support the hypothesis that cyclic AMP promotes the elongation of cell processes by stimulating the assembly of microtubules from existing tubulin.

scholarly journals The regulation of growth hormone secretion from the isolated rat anterior pituitary in vitro. The role of adenosine 3′:5′-cyclic monophosphate

1971 ◽  
Vol 124 (4) ◽  
pp. 815-826 ◽  
Author(s):  
R. B. Lockhart Ewart ◽  
K. W. Taylor
Keyword(s):  
Growth Hormone ◽  
Cyclic Amp ◽  
Early Phase ◽  
Late Phase ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Hormone Release ◽  
Dibutyryl Cyclic Amp ◽  
Cyclic Monophosphate

1. The release of growth hormone from isolated fragments of rat anterior pituitary tissue incubated in vitro was studied by employing a double-antibody radioimmunoassay. 2. In the absence of added stimuli, two phases of hormone release could be distinguished, an early phase of 2h duration and a subsequent late phase. In the early phase, hormone release was rapid but could be significantly decreased by calcium depletion and by 2,4-dinitrophenol whereas the rate of release in the late phase was uninfluenced by these incubation conditions. These results have been interpreted as indicating the existence of a secretory component in the early phase of release. 3. In subsequent experiments, the effects of various agents on the rate of hormone output during the late phase of incubation were investigated. Hormone release was increased by theophylline and by dibutyryl cyclic AMP (N6-2′-O-dibutyryl-adenosine 3′:5′-cyclic monophosphate), the response to both of these agents being related to the concentration of the stimulant employed. 4. The stimulation of growth hormone output by theophylline was significantly decreased by calcium deprivation and by 2,4-dinitrophenol. The response to dibutyryl cyclic AMP was diminished by 2,4-dinitrophenol, iodoacetate and 2-deoxyglucose but not by malonate or colchicine. 5. Arginine, β-hydroxybutyrate, albumin-bound palmitate and variation in the glucose concentration of the incubation medium over a wide range were without any statistically significant effect on the rate of hormone release from either control pituitary fragments or those subject to secretory stimulation by dibutyryl cyclic AMP. 6. It is suggested that the regulation of growth hormone secretion is mediated by cyclic AMP (adenosine 3′:5′-cyclic monophosphate). The secretion observed in response to cyclic AMP requires the presence of ionized calcium and a source of metabolic energy but is independent of pituitary protein synthesis de novo. The integrity of the glycolytic pathway of glucose metabolism appears to be essential for cyclic AMP-stimulated growth hormone secretion to occur.

scholarly journals Dibutyryladenosine 3′:5′-cyclic monophosphate-mediated changes in rat cells involve macromolecular alterations in vinblastine-precipitable proteins

1978 ◽  
Vol 174 (3) ◽  
pp. 1071-1074
Author(s):  
A T Meza ◽  
M Rieber
Keyword(s):  
Molecular Weight ◽  
Cyclic Amp ◽  
Cell Cultures ◽  
Cyclic Nucleotide ◽  
Dibutyryl Cyclic Amp ◽  
Cyclic Monophosphate ◽  
Three Components

ts-NT3-KR rat cell cultures show the loss of three components in the molecular-weight region 200,000–250,000 when exposed to dibutyryl cyclic AMP, under conditions of both restriction and expression of the transformed phenotype. Vinblastine is able to precipitate preferentially from control cultures the species that are decreased by exposure to the cyclic nucleotide. Serum-starved cultures exposed to dibutyryl cyclic AMP reveal differences in their vinblastine precipitates, depending on whether the expression of the transformation phenotype is restricted or not.

scholarly journals HUMAN T LYMPHOCYTE "E" ROSETTE FUNCTION

1974 ◽  
Vol 140 (4) ◽  
pp. 1122-1126 ◽  
Author(s):  
Francis V. Chisari ◽  
Thomas S. Edgington
Keyword(s):  
T Lymphocytes ◽  
Cyclic Amp ◽  
Cholera Toxin ◽  
T Lymphocyte ◽  
Blood Cells ◽  
Adenyl Cyclase ◽  
Dibutyryl Cyclic Amp ◽  
Substantial Evidence ◽  
Human T Lymphocyte ◽  
Normal Human

The capacity of normal human T lymphocytes to form rosettes with sheep red blood cells can be inhibited by drugs or agents which induce elevations in intracellular levels of cyclic AMP. The effect is early in the presence of agents which elicit rapid elevations in intracellular cyclic AMP (isoproterenol, aminophylline) and occurs later in the presence of cholera toxin which induces a dalayed increase in endogenous cyclic AMP. Dibutyryl cyclic AMP is inhibitory, and the effects of dibutyryl cyclic AMP and the adenyl cyclase stimulators are potentiated by inhibition of phosphodiesterase. These data provide substantial evidence that elevation of intracellular cyclic AMP diminishes E rosette function of lymphocytes.

MSH inhibits growth in a line of amelanotic hamster melanoma cells and induces increases in cyclic AMP levels and tyrosinase activity without inducing melanogenesis

1989 ◽  
Vol 92 (4) ◽  
pp. 551-559
Author(s):  
A. Slominski ◽  
G. Moellmann ◽  
E. Kuklinska
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Melanoma Cells ◽  
Amelanotic Melanoma ◽  
Tyrosinase Activity ◽  
Melanin Synthesis ◽  
Melanocyte Stimulating Hormone ◽  
Inhibit Cell Growth ◽  
Hamster Melanoma ◽  
Peak Increase

In Bomirski Ab amelanotic hamster melanoma cells, L-tyrosine and/or L-dopa induce increases in tyrosinase activity as well as synthesis of melanosomes and melanin. L-tyrosine also modifies melanocyte-stimulating hormone (MSH) binding. In this paper we show that in the Bomirski amelanotic melanoma system MSH and agents that raise intracellular cyclic AMP induce dendrite formation, inhibit cell growth, and cause substantial increases in tyrosinase activity without inducing melanin synthesis. Tyrosinase activity is detected only in broken cell preparations, or cytochemically in fixed cells. In the continued absence of mature melanosomes, the induced enzyme remains in elements of the trans-Golgi reticulum. Comparative measurements of cyclic AMP in amelanotic and tyrosine-induced melanotic cells show similar basal levels. L-tyrosine and L-dopa have little or no effect, whereas MSH may cause a 1000% peak increase in cyclic AMP levels both in amelanotic and melanotic cells. None of these agents influences cyclic GMP or inositol trisphosphate (InsP3) levels. In agreement with the InsP3 assays, phorbol ester (TPA) has no effect on melanization, tyrosinase activity or cell proliferation. In conclusion, in the Bomirski amelanotic melanoma, MSH induces only partial cell differentiation associated with raised levels of cyclic AMP. Induction of melanosome synthesis and melanization by L-tyrosine or L-dopa appear to follow pathways unrelated to cyclic AMP, cyclic GMP or InsP3.

EFFECT OF DIBUTYRYL CYCLIC AMP ON THE RELEASE OF MELANOCYTE-STIMULATING HORMONE FROM RAT NEUROINTERMEDIATE LOBES IN VITRO

1974 ◽  
Vol 63 (3) ◽  
pp. 533-538 ◽  
Author(s):  
BRIDGET I. BAKER
Keyword(s):  
Cyclic Amp ◽  
Gel Electrophoresis ◽  
Incubation Medium ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Dibutyryl Cyclic Amp ◽  
Melanocyte Stimulating Hormone ◽  
Low Concentrations ◽  
Stimulating Hormone

SUMMARY A method for measuring melanocyte-stimulating hormone (MSH) in rat neurointermediate lobe in vitro and in incubation medium, using polyacrylamide gel electrophoresis, is described. Using this technique, it was shown that dibutyryl cyclic AMP increased the release of MSH in vitro, the degree of stimulation depending on the concentration of the nucleotide. The effect of low concentrations of the nucleotide was potentiated by theophylline.

scholarly journals Comparative studies on the carbohydrate-containing membrane components of normal and adenosine 3′:5′-cyclic monophosphate-treated Chinese-hamster ovary cells

1973 ◽  
Vol 134 (1) ◽  
pp. 329-339 ◽  
Author(s):  
M. Mansoor Baig ◽  
R. M. Roberts
Keyword(s):  
Cyclic Amp ◽  
Cell Surface ◽  
Chinese Hamster Ovary ◽  
Chinese Hamster Ovary Cells ◽  
Sodium Dodecyl ◽  
Chinese Hamster ◽  
Double Labelling ◽  
Dibutyryl Cyclic Amp ◽  
Ovary Cells ◽  
Cyclic Monophosphate

1. We investigated some of the changes in plasma-membrane composition that accompany the alteration in cell growth and morphology induced by treating Chinese-hamster ovary cells with dibutyryladenosine 3′:5′-cyclic monophosphate (dibutyryl cyclic AMP). 2. A double-labelling technique was employed in which normal cells were given 14C-labelled precursor, and those treated with dibutyryl cyclic AMP were given 3H label. l-Leucine, d-glucosamine, and l-fucose were used to label the membranes. 3. After 3 days growth, the two populations of cells were harvested by trypsin treatment, the cells were pooled, and plasma membranes isolated. Proteins and glycoproteins of the membranes were separated by electrophoresis on sodium dodecyl sulphate–polyacrylamide gels, and the radioactive profiles for 14C and 3H and the staining patterns with Amido Black were compared. 4. Although certain components of the membrane from treated cells showed marked quantitative changes, there was neither major addition nor major deletions of components. 5. Complete proteolysis of the mixed membranes, of the material released from the cell surface by trypsin, and of the glycoproteins released from the cells into the medium, gave a series of radioactive glycopeptides when either fucose or glucosamine was employed as precursor. 6. After such glycopeptides were fractionated on columns of Sephadex G-50, marked differences in the elution profiles of 3H and 14C were noted. Dibutyryl cyclic AMP evidently causes alterations in the overall composition of the carbohydrate components of the cell surface. It was not possible to decide whether this was solely the result of the same glycoproteins being formed but in different proportions, or the result of modifications of oligosaccharide side chains on some of the glycoproteins. 7. Some of the changes were not unlike the reverse of those that accompany the transformation of fibroblasts by oncogenic viruses, and our results lend credence to the idea that the lowered amount of cyclic AMP noted in transformed cells is responsible for their altered surface properties.

Bromodeoxyuridine- and cyclic AMP-mediated regulation of tyrosinase in Syrian hamster melanoma cells

1990 ◽  
Vol 16 (6) ◽  
pp. 583-592 ◽  
Author(s):  
Sikha Rauth ◽  
George E. Hoganson ◽  
Richard L. Davidson
Keyword(s):  
Cyclic Amp ◽  
Syrian Hamster ◽  
Melanoma Cells ◽  
Hamster Melanoma

Stimulation by thyrotropin, cholera toxin and dibutyryl cyclic AMP of the multiplication of differentiated thyroid cells in vitro

1982 ◽  
Vol 26 (1-2) ◽  
pp. 165-176 ◽  
Author(s):  
Pierre P. Roger ◽  
Anouk Hotimsky ◽  
Colette Moreau ◽  
Jacques E. Dumont
Keyword(s):  
Cyclic Amp ◽  
Cholera Toxin ◽  
Dibutyryl Cyclic Amp ◽  
Thyroid Cells
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