In vitro modulation of porcine Leydig cell steroidogenesis by phorbol-12-myristate-13-acetate and 1,2-dioctanoylglycerol

Abstract Serum-free primary cultures of neonatal (1-day-old) porcine Leydig cells were used to study the effects of phorbol-12-myristate-13-acetate and 1,2-dioctanoylglycerol on testosterone and pregnenolone production. Phorbol-12-myristate-13-acetate alone from 0.001-10 μmol/l stimulated testosterone and pregnenolone production, whereas 1,2-dioctanoylglycerol alone had no effect on steroid production, relative to control. Phorbol12-myristate-13-acetate and 1,2-dioctanoylglycerol each inhibited pLH-stimulated testosterone and pregnenolone production. To further clarify the influence of these protein kinase C activators on steroidogenesis, cultured Leydig cells were treated with either phorbol-12-myristate-13-acetate or 1,2-dioctanoylglycerol plus forskolin (an adenylate cyclase activator). Both phorbol-12-myristate-13-acetate and 1,2-dioctanoylglycerol inhibited forskolin-stimulated testosterone production. Phorbol-12-myristate-13-acetate had no effect on forskolin-stimulated pregnenolone production and only the highest concentration of 1,2-dioctanoylglycerol (100 μmol/l) inhibited forskolin-stimulated production of pregnenolone. These data demonstrate that porcine Leydig cell steroidogenesis can be modulated by interactions of the protein kinase C and protein kinase A second messenger systems.

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Effects of protein kinase C activation on cyclic AMP and testosterone production of rat Leydig cells in vitro

Acta Endocrinologica ◽

10.1530/acta.0.1210327 ◽

1989 ◽

Vol 121 (3) ◽

pp. 327-333 ◽

Cited By ~ 16

Author(s):

Hannu Nikula ◽

Ilpo Huhtaniemi

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Pertussis Toxin ◽

Leydig Cells ◽

Endocrine Function ◽

Camp Production ◽

Testosterone Production ◽

Kinase C ◽

Protein Kinase C Activation

Abstract. The role of protein kinase C in modulation of the endocrine function of rat Leydig cells was studied. Percoll-purified rat Leydig cells were stimulated with hCG, forskolin, cholera toxin, pertussis toxin and 8-bromo-cAMP in the presence and absence of two activators of protein kinase C, 12-0-tetradecanoylphorbol 13-acetate (TPA) or 1-oleoyl-2-acetyl-sn-glycerol (OAG). The two activators had no effect on basal cAMP, but decreased hCG-stimulated, and increased cholera toxinand forskolin-stimulated cAMP production. Cells pre-incubated with pertussis toxin showed enhanced rate of cAMP production in response to forskolin, but were no more responsive to TPA and OAG stimulation. These findings suggest that protein kinase C activation may on one hand inhibit the LH-receptor and Gs-protein coupling and on the other hand inhibit the Gi-protein mediated suppression of adenylyl cyclase activity. TPA and OAG effects on testosterone production were measured in the absence and presence of 8-bromo-cAMP stimulation. TPA enhanced basal testosterone production, but this effect was shifted to inhibition when steroidogenesis was stimulated by 8-bromo-cAMP. The OAG effect on testosterone production was inhibitory throughout the dose-response curve of 8-bromo-cAMP. The basal stimulation of testosterone production by TPA was probably due to a marginal increase of cAMP caused by inhibition of the Gi-protein, since a similar effect was observed by pertussis toxin, and therafter TPA was without effect on testosterone. The inhibition of stimulated testosterone production by TPA and OAG indicates that protein kinase C activity also affects steroidogenesis at a step(s) beyound cAMP formation.

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The protein kinase C activators cis-9,10-methyleneoctadecanoic acid and TPA inhibit Helicobacter pylori induced apoptosis in gastric epithelial cells in vitro

Gastroenterology ◽

10.1016/s0016-5085(00)85185-9 ◽

2000 ◽

Vol 118 (4) ◽

pp. A762

Author(s):

Barbara Obst ◽

Siegfried Wagner ◽

Winfried Beil

Keyword(s):

Helicobacter Pylori ◽

Protein Kinase C ◽

Protein Kinase ◽

Epithelial Cells ◽

Gastric Epithelial Cells ◽

Kinase C ◽

Protein Kinase C Activators ◽

Induced Apoptosis

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Protein Kinase C: A Putative New Target for the Control of Human Medullary Thyroid Carcinoma Cell Proliferation in Vitro

Endocrinology ◽

10.1210/en.2011-1988 ◽

2012 ◽

Vol 153 (5) ◽

pp. 2088-2098 ◽

Cited By ~ 12

Author(s):

Daniela Molè ◽

Erica Gentilin ◽

Teresa Gagliano ◽

Federico Tagliati ◽

Marta Bondanelli ◽

...

Keyword(s):

Cell Proliferation ◽

Protein Kinase C ◽

Protein Kinase ◽

Thyroid Carcinoma ◽

Medullary Thyroid Carcinoma ◽

Glycogen Synthase ◽

Primary Cultures ◽

Medullary Thyroid ◽

Kinase C

We investigate the role of protein kinase C (PKC) in the control of medullary thyroid carcinoma (MTC) cell proliferation by a PKC inhibitor, Enzastaurin, in human MTC primary cultures and in the TT cell line. We found that PKC inhibition reduces cell proliferation by inducing caspase-mediated apoptosis and blocks the stimulatory effect of IGF-I on calcitonin secretion. Enzastaurin reduces PKCβII (Thr500) phosphorylation, indicating a direct involvement of this isoform as well as the phosphorylated levels of Akt (Ser 473) and glycogen synthase kinase (Ser9), PKC pathway downstream targets and pharmacodynamic markers for PKC inhibition. PKCβII and PKCδ enzyme isoforms expression and localization were investigated. These data indicate that in vitro PKC is involved in the control of human MTC proliferation and survival by modulating apoptosis, with a mechanism that implicates PKCβII inhibition and translocation in different subcellular compartments. Targeting PKC may represent a useful therapeutic approach for controlling MTC proliferation.

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