scholarly journals Receptor-mediated gonadotropin action in the ovary. Inhibitory actions of concanavalin A and wheat-germ agglutinin on gonadotropin-stimulated cyclic AMP and progesterone responses in ovarian cells

1981 ◽  
Vol 200 (1) ◽  
pp. 153-159 ◽  
Author(s):  
S Azhar ◽  
K M Menon
Keyword(s):  
Cyclic Amp ◽  
Concanavalin A ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Carbohydrate Chain ◽  
Inhibitory Effect ◽  
Dolichos Biflorus ◽  
Acetylneuraminic Acid ◽  
Ovarian Cells ◽  
Proline Incorporation

Pretreatment of ovarian cells with concanavalin A and wheat-germ agglutinin blocked the gonadotropin-induced cyclic AMP and progesterone responses and this effect was time- and concentration-dependent. Basal production of either cyclic AMP or progesterone, however, was not affected by treatment of cells with lectin. The effect of concanavalin A on gonadotropin-mediated cyclic AMP and progesterone responses was blocked by alpha-methyl D-mannoside and alpha-methyl d-glucoside. Similarly the inhibitory effect of wheat-germ agglutinin was reversed by N-acetyl-D-glucosamine. Pretreatment of ovarian cells with concanavalin A or wheat-germ agglutinin had no effect on protein synthesis in the ovary as monitored by [3H]proline incorporation studies. Concanavalin A and wheat-germ agglutinin did not affect steroid production in response to dibutyryl cyclic AMP and 8-bromo cyclic AMP, indicating that the inhibitory action of lectin was occurring at a step before cyclic AMP formation. Lectins specific for L-fucose, D-galactose and N-acetyl-D-galactosamine, gorse seed agglutinin, peanut agglutinin and Dolichos biflorus agglutinin respectively, did not interfere with gonadotropin-induced cyclic AMP and progesterone responses. The present studies suggest that gonadotropin receptors may be glycoprotein in nature or closely associated with glycoprotein structures with the carbohydrate chain containing N-acetyl-D-glucosamine, mannose and possibly N-acetylneuraminic acid.

scholarly journals Influence of Concanavalin A, wheat germ agglutinin, and soybean agglutinin on the fusion of myoblasts in vitro.

1975 ◽  
Vol 67 (3) ◽  
pp. 826-834 ◽  
Author(s):  
H Den ◽  
D A Malinzak ◽  
H J Keating ◽  
A Rosenberg
Keyword(s):  
Concanavalin A ◽  
Binding Sites ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Inhibitory Effect ◽  
Myoblast Fusion ◽  
Normal Serum ◽  
Specific Cell ◽  
Number Of Binding Sites

Although muscle cell fusion was shown to be an energy-requiring process, release of myoblasts from an EGTA fusion block could be accomplished with Earle's balanced salt solution (containing 1.8 mM Ca++) free of glucose or any other energy-produced metabolite. The effect of concanavalin A, abrin, and the lectins from wheat germ, soybean, and Lens culinaris on myoblast fusion was examined with synchronized myoblast cultures upon release from fusion block. At a concentration of 15 mug/ml, these lectins were found to inhibit the fusion process to the extent of 62%, 41%, 32%, 8%, and 19%, respectively. Concanavalin A inhibition could be prevented by alpha-methyl-D-mannoside. The inhibitory effect of all the lectins except abrin could be reversed by changing to the normal, serum-containing medium. The number of binding sites was 3.4 X 10(7), 6.1 X 10(7), and 1.7 X 10(6), respectively. Although myoblasts were found to have about twice as many binding sites for wheat germ agglutinin as for concanavalin A, concanavalin A was determined to be twice as effective as wheat germ agglutinin as an inhibitor of myoblast fusion. These findngs raise the possibility that specific cell surface glycoproteins may be an important factor in this process.

Phagocytic specificity during sexual development in Dictyostelium discoideum

1986 ◽  
Vol 32 (2) ◽  
pp. 79-82 ◽  
Author(s):  
Keith E. Lewis ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Concanavalin A ◽  
Sexual Development ◽  
Wheat Germ ◽  
Giant Cells ◽  
Inhibitory Effect ◽  
Sexual Cycle ◽  
Type I ◽  
Further Development ◽  
Type Receptor

During the sexual cycle of Dictyostelium discoideum, zygote giant cells develop and serve as foci for further development by chemoattracting and cannibalizing hundreds of local amoebae. Previous work has shown that the phagocytic process bears similarities to and differences from asexual endocytosis. In the present study, sexual phagocytosis in D. discoideum was found to be species and developmental stage specific. It was inhibited selectively by glucose and concanavalin A. Although a partial, inhibitory effect of mannose on phagocytosis was not statistically significant, alpha-methylmannosamine, like alpha-methyl-glucose, significantly restored the phagocytic competence of giant cells treated with concanavalin A. Other sugars (N-acetyl glucosamine, N-acetylgalactosamine, and galactose) and lectins (wheat germ agglutinin, Ulex europus type I, and Ricinis communis agglutinin type I) had no significant effect on sexual phagocytosis. Together these data indicate that a glucose-type receptor is involved in selective uptake of D. discoideum amoebae by giant cells.

scholarly journals Mechanism of neutrophil chemiluminescence induced by wheat germ agglutinin: partial characterization of the antigens recognized by wheat germ agglutinin

Blood ◽  
1984 ◽  
Vol 64 (5) ◽  
pp. 1094-1102 ◽  
Author(s):  
Y Ozaki ◽  
J Iwata ◽  
T Ohashi
Keyword(s):  
Membrane Proteins ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Sodium Dodecyl ◽  
Submaxillary Gland ◽  
Binding Property ◽  
Molecular Weights ◽  
Acetylneuraminic Acid ◽  
Cell Extracts ◽  
High Concentrations

Abstract Wheat germ agglutinin (WGA) stimulated neutrophils to produce significant levels of luminol-dependent chemiluminescence (CL). Since WGA is known to bind N-acetylglucosamine (GlcNAc) oligomers and N- acetylneuraminic acid (NANA), we attempted to determine which binding property of WGA is essential for induction of CL. The succinylated form of WGA (SuWGA), which is no longer able to bind NANA, was still able to induce CL. N-Acetylglucosamine at a concentration of 20 mmol/L almost completely inhibited WGA-induced CL production by neutrophils, whereas bovine submaxillary gland mucin, a potent blocker of NANA binding of WGA, failed to inhibit CL production. Lectins with the GlcNAc-binding property were examined for their ability to induce CL. Those that have higher valences and have a tendency to bind GlcNAc oligomers in the internal portion of glycoconjugates were able to induce CL, whereas those that have low valences and bind terminal GlcNAc of glycoconjugates failed to induce CL even at high concentrations. Attempts were made to characterize the neutrophil membrane proteins recognized by WGA. Glycoproteins with a molecular weight of 25,000 daltons were identified by a 50 mmol/L GlcNAc elution of WGA gels loaded with 125I-labeled neutrophil membrane proteins. Elution with 500 mumol/L GlcNAc trimer produced several glycoproteins of different molecular weights in addition to the glycoproteins of 25,000 daltons. 125I-labeled WGA and SuWGA were used for autoradiographic analysis of cell extracts of the neutrophils separated on sodium dodecyl sulfate polyacrylamide gels. WGA recognized multiple glycoproteins of different molecular weights, whereas SuWGA bound only a few of them. Glycoproteins of 25,000 daltons, probably corresponding to those identified by 50 mmol/L GlcNAc elution, were also recognized.

Inhibition of H+ secretion by lectins in turtle bladder: role of a cell type on acidification

1985 ◽  
Vol 248 (5) ◽  
pp. R584-R594
Author(s):  
D. M. Potter ◽  
J. A. Arruda
Keyword(s):  
Concanavalin A ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Granular Cell ◽  
Cell Fraction ◽  
Dependent Manner ◽  
O2 Consumption ◽  
Cell Type ◽  
Double Labeling ◽  
Morphological Studies

Because certain lectins have been shown to bind to the intercalated cell of the cortical collecting tubule, we investigated the effect of concanavalin A and wheat germ agglutinin on urinary acidification in isolated turtle bladders. After addition to the mucosal but not serosal fluid, concanavalin A and wheat germ agglutinin decreased H+ secretion in a dose-dependent manner, and these effects were specifically inhibited by the competitive antagonists of concanavalin A (alpha-methyl-D-mannoside) and of wheat germ agglutinin (N-acetylglucosamine). Concanavalin A decreased H+ secretion by decreasing both the proton motive force and the active conductance of protons. Although electroneutral HCO3 secretion was not inhibited by either lectin, Na transport was decreased by 18 and 25%, respectively, after concanavalin A and wheat germ agglutinin. Concanavalin A failed to inhibit O2 consumption by the granular cell fraction but significantly inhibited O2 consumption by the carbonic anhydrase rich cell fraction. Morphological studies utilizing peroxidase or fluorescein-labeled concanavalin A showed that concanavalin A stained one cell type and that this staining was specific since it could be blocked by the competitive antagonist alpha-methyl-D-mannoside. Studies utilizing double labeling with fluorescein concanavalin A and acridine orange suggested that both probes stain the same cell type. The data strongly suggest that concanavalin A interacts specifically with the cell responsible for H+ secretion.

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