scholarly journals The effect of calcium ions on testosterone production in Leydig cells from rat testis

1976 ◽  
Vol 160 (3) ◽  
pp. 433-437 ◽  
Author(s):  
F H A Janszen ◽  
B A Cooke ◽  
M J A Van Driel ◽  
H J Van Der Molen
Keyword(s):  
Protein Kinase ◽  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Calcium Ions ◽  
Incubation Medium ◽  
Leydig Cells ◽  
Luteinizing Hormone Receptor ◽  
Dependent Protein Kinase ◽  
Testosterone Production ◽  
Dependent Protein

Leydig-cell suspensions, prepared from rat testes, were incubated with different amounts of Ca2+ with and without added luteinizing hormone. The basal testosterone production in the absence of luteinizing hormone was unaffected by the Ca2+ concentration in the incubation medium. The luteinizing hormone-stimulated testosterone production, however, was progressively decreased in the absence of Ca2+ to one-third of that with 2.50 mM-Ca2+. This decrease in luteinizing hormone-stimulated testosterone production was independent of the different concentrations of luteinizing hormone (0-10μg/ml) used and could be restored by the addition of Ca2+ to the incubation medium. The restoration of the stimulation was achieved within 30 min after the addition of Ca2+ to the medium. Activation of cyclic AMP-dependent protein kinase by luteinizing hormone was not decreased by omission of Ca2+ from the incubation medium, suggesting that Ca2+ may be involved in steroidogenesis at a stage beyond the luteinizing hormone receptor-adenylate cyclase-protein kinase system.

ACTIVATION INDUCED BY LUTEINIZING HORMONE OF TYPE II PROTEIN KINASE DEPENDENT ON CYCLIC ADENOSINE MONOPHOSPHATE AND PHOSPHORYLATION OF SOLUBLE PROTEINS IN PORCINE GRANULOSA CELLS

1980 ◽  
Vol 84 (1) ◽  
pp. 49-63 ◽  
Author(s):  
D. H. HALPREN-RUDER ◽  
R. A. JUNGMANN ◽  
W. J. GEORGE ◽  
J. R. JETER
Keyword(s):  
Protein Kinase ◽  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Granulosa Cell ◽  
Granulosa Cells ◽  
Type Ii ◽  
Dependent Protein Kinase ◽  
Porcine Granulosa Cells ◽  
Dependent Protein ◽  
Dose Dependent

The present experiments were designed to study whether exogenous LH could elicit acute cyclic AMP-mediated activation of cyclic AMP-dependent protein kinase and phosphorylation of cellular protein in intact porcine granulosa cells. Incubation of porcine granulosa cells (from 3 to 5 mm diameter follicles) with 2 μg luteinizing hormone/ml (LH) caused a significant rise of cellular cyclic AMP content within 2 min of the addition of LH. The increase was dose-dependent and occurred between doses of 0·2 and 2·0 μg LH/ml. Luteinizing hormone also caused a time- and dose-dependent dissociation of the type II cyclic AMP-dependent protein kinase isozyme in porcine granulosa cells. Luteinizing hormone (0·05–2 μg/ml) significantly dissociated the cyclic AMP-dependent protein kinase between 2 and 30 min after stimulation. The protein kinase dissociation was a specific effect of LH and was not elicited by either adrenocorticotrophic hormone or prolactin. During the period of LH-induced protein kinase activation, several soluble granulosa cell proteins, ranging in molecular weights from about 43 000 to 99 000, became phosphorylated in a time-dependent and hormone-specific manner. The results suggest that cyclic AMP-mediated activation of granulosa cell type II cyclic AMP-dependent protein kinase may be a prerequisite in the short-term molecular action of LH leading to LH-specific phosphorylation of several soluble granulosa cell proteins of an as yet unidentified function.

scholarly journals Correlation of protein kinase activation and testosterone production after stimulation of Leydig cells with luteinizing hormone

1976 ◽  
Vol 160 (3) ◽  
pp. 439-446 ◽  
Author(s):  
B A Cooke ◽  
M L Lindh ◽  
F H A Janszen
Keyword(s):  
Protein Kinase ◽  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Leydig Cell ◽  
Leydig Cells ◽  
Kinase Activation ◽  
Testosterone Production ◽  
Protein Kinase Activation ◽  
Stimulation Of

The effect of different doses of luteinizing hormone on activation of protein kinases, cyclic AMP and testosterone production was studied in purified rat testis Leydig-cell preparations in the presence of 3-isobutyl-1-methylxanthine (a phosphodiesterase inhibitor). In addition, the nature of the protein kinases present in these cells and other tissues was investigated. The following results were obtained. 1. With all the amounts of luteinizing hormone used (0.1-1000 ng/ml), both activation of protein kinase and stimulation of testosterone production were demonstrated. With the lowest amount of luteinizing hormone (0.1 ng/ml), an 8.4±0.9% (S.E.M.,n=6) stimulation of protein kinase activation occurred, increasing to 100% with 1000 ng/ml, compared with 3.2±1.0%(S.E.M.,n=7) and 100% stimulation of testosterone production with 0.1 and 100 ng/ml respectively. 2. With amounts of luteinizing hormone up to 1 ng/ml (which gave half-maximal stimulation of testosterone production) no detectable increases in net cyclic AMP production were obtained. With higher amounts of luteinizing hormone, cyclic AMP production increased, but maximal production was not reached with 1000 ng/ml. 3. Two isoenzymic forms of protein kinase were present in Leydig cells and seminiferous tubules; type I was eluted with 0.075 M-and type II with 0.22-0.25 M-NaCl from DEAE-cellulose columns. 4. The protein kinase activity was not affected by the presence of erythrocytes in the Leydig-cell preparation, but varied depending on the type of histone used as substrate (histone F2b > mixed > histone F1).

scholarly journals A cytosolic cyclic AMP-dependent protein kinase in Dictyostelium discoideum. I. Properties.

1984 ◽  
Vol 259 (1) ◽  
pp. 654-661 ◽  
Author(s):  
I H Majerfeld ◽  
B H Leichtling ◽  
J A Meligeni ◽  
E Spitz ◽  
H V Rickenberg
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Dependent Protein Kinase ◽  
Dependent Protein
Sign in / Sign up

Export Citation Format

Share Document