scholarly journals Changes in cAMP-dependent protein kinase (PKA) and progesterone secretion in luteinizing human granulosa cells

2004 ◽  
Vol 183 (1) ◽  
pp. 39-50 ◽  
Author(s):  
E C Chin ◽  
T E Harris ◽  
D R E Abayasekara
Keyword(s):  
Protein Kinase ◽  
Granulosa Cells ◽  
Gradient Centrifugation ◽  
Dependent Manner ◽  
Dependent Protein Kinase ◽  
Human Granulosa Cells ◽  
Camp Dependent Protein Kinase ◽  
Progesterone Secretion ◽  
Dependent Protein ◽  
Dose Dependent

Luteinization of follicular granulosa cells leads to an increase in progesterone secretion that is regulated by luteinizing hormone (LH). LH acts mainly by elevating intracellular cyclic 3′,5′-adenosine monophosphate (cAMP) and activating cAMP-dependent protein kinase (PKA). In this study, we have examined the role of PKA in relation to progesterone output by luteinizing human granulosa cells. Human granulosa cells were obtained by percoll gradient centrifugation of follicular aspirates of patients undergoing oocyte retrieval for assisted conception. Cells were cultured in serum-supplemented medium for up to 3 days in the presence and/or absence of human (h)LH and other cAMP-elevating agents. Spent medium was assayed for cAMP and progesterone content by specific RIA. Cell lysates were collected and assessed for PKA regulatory (R)IIα/catalytic (C)α expression by Western blotting. Although basal progesterone secretion increased progressively throughout culture, cAMP levels remained unchanged. Under basal conditions, PKA RIIα/Cα expression appeared to increase throughout the 3-day culture period. In the presence of hLH and other cAMP-elevating agents, progesterone secretion increased in a dose-dependent manner coincident with an increase in cAMP. However, despite the increase in both progesterone secretion and cAMP accumulation, there was a dose-dependent decrease in both PKA RIIα and Cα expression. Thus, data presented in this study show that increases in progesterone secretion in luteinizing human granulosa cells can be dissociated from increases in PKA expression. This notion implies that progesterone secretion may be regulated by PKA-dependent as well as PKA-independent mechanisms.

scholarly journals Progesterone secretion by luteinizing human granulosa cells: a possible cAMP-dependent but PKA-independent mechanism involved in its regulation

2004 ◽  
Vol 183 (1) ◽  
pp. 51-60 ◽  
Author(s):  
E C Chin ◽  
D R E Abayasekara
Keyword(s):  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Granulosa Cells ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Nucleotide Exchange ◽  
Independent Manner ◽  
Human Granulosa Cells ◽  
Progesterone Secretion ◽  
Dose Dependent

The corpus luteum formed after luteinization of follicular cells secretes progesterone under the control of luteinizing hormone (LH). Binding of LH to its G-protein-coupled receptor leads to the activation of the adenylate cyclase/ cyclic AMP (cAMP)/cAMP-dependent protein kinase (PKA) signalling pathway. The identification of a new class of cAMP-binding proteins termed ‘guanine nucleotide exchange factors’ (cAMP-GEFs) provides a means by which changes in cAMP could yield actions that are independent of PKA. Hence, in this study, we have explored the hypothesis that steroidogenesis in luteinizing cells is mediated in both a cAMP/PKA-dependent and cAMP-dependent, but PKA-independent, manner. Human granulosa cells were isolated from follicular aspirates of women undergoing assisted conception. Luteinizing human granulosa cells were cultured for up to 3 days in the presence of human (h)LH and the adenylate cyclase activator forskolin in the added presence or absence of increasing doses of the PKA inhibitors H89 (N-[2-(4-bromocinnamylamino)ethyl] 5-isoquinoline) and PKI (myristoylated protein kinase A inhibitor amide 14–22) or the cAMP antagonist, Rp-cAMP. Agonist-stimulated progesterone secretion was inhibited in a dose-dependent manner by the PKA inhibitors and the cAMP antagonist, with decreasing sensitivity as luteinization progressed. Pretreatment of granulosa cells for 4 h with human (h)LH reduced the effectiveness of H89 in inhibiting progester-one secretion. Under basal conditions, cAMP-GEFI expression increased progressively throughout culture, and this could be further enhanced when cells were incubated with increasing doses of LH and forskolin. Furthermore, incubation of cells in the presence of increasing concentrations of the novel cAMP-GEF-specific cAMP analogue, 8 CPT-2 ME-cAMP (8-(4-chloro-phenylthio)-2′-0-methyladenosine-3′,5′-cyclic monophosphate), increased progesterone secretion in a dose-dependent manner. The results show that increases in cAMP generated by LH and forskolin, in addition to activating PKA, also induce increases in cAMP-GEFI protein expression in luteinizing human granulosa cells. In addition, activation of cAMP-GEFI results in increased progesterone secretion. Hence, increases in cAMP lead to the activation of PKA-dependent, as well as PKA-independent but cAMP-dependent (via cAMP-GEFI), signalling mechanisms. Since cAMP-GEFs have the capacity to activate the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-K)/protein kinase B (PKB) signalling pathways, these may provide the potential mechanisms by which cAMP-dependent but PKA-independent progesterone synthesis is regulated.

scholarly journals Ca2+ and phospholipid-dependent protein kinase (protein kinase C) activity is not necessarily required for secretion by human neutrophils

Blood ◽  
1986 ◽  
Vol 68 (4) ◽  
pp. 810-817
Author(s):  
KJ Balazovich ◽  
JE Smolen ◽  
LA Boxer
Keyword(s):  
Protein Kinase ◽  
Phorbol Esters ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Soluble Form ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Dose Dependent

Ca2+-dependent and phospholipid-dependent protein kinase (PKC) is a receptor for and is activated by phorbol esters. This enzyme is reportedly involved in the mechanism of superoxide anion (O2-) production and the release of intracellular granule contents from human neutrophils. As previously reported by others, we found that greater than 75% of the total cellular PKC activity existed in a soluble form in untreated neutrophils and that this activity was enhanced in a dose- dependent manner by phorbol 12-myristate 13-acetate (PMA) and by phorbol 12,13-dibutyrate (PDBu). Furthermore, mezerein, an analogue of PMA that is thought to be a competitive inhibitor, did not activate PKC, and on the contrary, inhibited PMA-stimulated activity in a dose- dependent manner. Pretreatment of intact neutrophils with PMA or PDBu caused the “translocation” of PKC activity to the insoluble cell fraction; PKC translocation was not detected after mezerein stimulation at any of the tested concentrations. Neither did mezerein cause an increase in intracellular Ca2+, as monitored by Quin 2 fluorescence. Both phorbol esters and mezerein stimulated intact neutrophils to generate O2- and release lysosomal enzymes into the extracellular medium. Finally sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis demonstrated key differences in the patterns of endogenous phosphoproteins of neutrophils stimulated with phorbol as compared with mezerein. We therefore suggest that PKC activation may not be the only pathway required to elicit neutrophil responses.

scholarly journals Regulation of prostaglandin synthesis by protein kinase C in mouse peritoneal macrophages

1989 ◽  
Vol 260 (2) ◽  
pp. 471-478 ◽  
Author(s):  
H J Pfannkuche ◽  
V Kaever ◽  
D Gemsa ◽  
K Resch
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Peritoneal Macrophages ◽  
Dependent Manner ◽  
Membrane Phospholipids ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Dependent Protein ◽  
Dose Dependent ◽  
Mouse Peritoneal Macrophages

Resident mouse peritoneal macrophages synthesized and released prostaglandins (PGs) when challenged with 12-O-tetradecanoylphorbol 13-acetate (TPA) or 1,2-dioctanoyl-sn-glycerol (DiC8). Both stimuli were found to activate Ca2+/phospholipid-dependent protein kinase C (PKC). 1-(5-Isoquinolinesulphonyl)-2-methylpiperazine (‘H-7’) and D-sphingosine, known to inhibit PKC by different mechanisms, were able to decrease the PKC activity of macrophages in a dose-dependent manner. Addition of either PKC inhibitor decreased PG synthesis and also the release of arachidonic acid (AA) from phospholipids induced by TPA or DiC8. Simultaneously TPA or DiC8 also decreased incorporation of free AA into membrane phospholipids of macrophages. AA incorporation could be restored, however, by pretreatment with the PKC inhibitors. Our results demonstrate an involvement of PKC in the regulation of PG synthesis in mouse peritoneal macrophages and provide further evidence that reacylation of released fatty acids may be an important regulatory step.

scholarly journals Adrenocorticotrophic hormone stimulates phosphotyrosine phosphatase SHP2 in bovine adrenocortical cells: phosphorylation and activation by cAMP-dependent protein kinase

2000 ◽  
Vol 352 (2) ◽  
pp. 483-490 ◽  
Author(s):  
Stéphane ROCCHI ◽  
Isabelle GAILLARD ◽  
Emmanuel VAN OBBERGHEN ◽  
Edmond M. CHAMBAZ ◽  
Isabelle VILGRAIN
Keyword(s):  
Protein Kinase ◽  
Kinase Assay ◽  
Dependent Manner ◽  
Adrenocorticotrophic Hormone ◽  
Adrenocortical Cells ◽  
Dependent Protein Kinase ◽  
Phosphotyrosine Phosphatase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

During activation of adrenocortical cells by adrenocorticotrophic hormone (ACTH), tyrosine dephosphorylation of paxillin is stimulated and this correlates with protrusion of filopodial structures and a decreased number of focal adhesions. These effects are inhibited by Na3VO4, a phosphotyrosine phosphatase inhibitor [Vilgrain, Chinn, Gaillard, Chambaz and Feige (1998) Biochem. J. 332, 533–540]. However, the tyrosine phosphatases involved in these processes remain to be identified. In this study, we provide evidence that the Src homology domain (SH)2-containing phosphotyrosine phosphatase (SHP)2, but not SHP1, is expressed in adrenocortical cells and is phosphorylated upon ACTH challenge. ACTH (10-8M) treatment of 32P-labelled adrenocortical cells resulted in an increase in phosphorylated SHP2. By probing SHP2-containing immunoprecipitates with an antibody to phosphoserine we found that SHP2 was phosphorylated on serine in ACTH-treated cells in a dose- and time-dependent manner. Furthermore, using an in vitro kinase assay, we showed that SHP2 was a target for cAMP-dependent protein kinase (PKA). Serine was identified as the only target amino acid phosphorylated in SHP2. Phosphorylation of SHP2 by PKA resulted in a dramatic stimulation of phosphatase activity measured either with insulin receptor substrate-1 or with the synthetic peptide [32P]poly(Glu/Tyr) as substrate. In an in-gel assay of SHP2-containing immunoprecipitates, phosphorylated in vitro by PKA or isolated from adrenocortical cells treated with 10nM ACTH, a pronounced activation of SHP2 activity was shown. These observations clearly support the idea that a PKA-mediated signal transduction pathway contributes to SHP2 regulation in adrenocortical cells and point to SHP2 as a possible mediator of the effects of ACTH.

scholarly journals Nerve growth factor action is mediated by cyclic AMP- and Ca+2/phospholipid-dependent protein kinases.

1986 ◽  
Vol 103 (3) ◽  
pp. 887-893 ◽  
Author(s):  
J Cremins ◽  
J A Wagner ◽  
S Halegoua
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Tyrosine Hydroxylase ◽  
Protein Kinase ◽  
Enzyme Activation ◽  
Dependent Protein Kinase ◽  
Nerve Growth ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Dose Dependent

Nerve growth factor (NGF) mediates the phosphorylation of tyrosine hydroxylase in PC12 cells on two distinct peptide fragments, separable by two-dimensional tryptic phosphopeptide mapping (phosphopeptides T1 and T3). Phorbol diester derivatives capable of activating Ca+2/phospholipid-dependent protein kinase (C-kinase) cause a specific phosphorylation of peptide T3 in a dose-dependent, saturable manner. Derivatives of the endogenous C-kinase activator diacylglycerol, also cause the phosphorylation of tyrosine hydroxylase on peptide T3. The C-kinase inhibitors chlorpromazine and trifluoperazine inhibit the phorbol diester stimulated phosphorylation of site T3 in a dose-dependent manner. These agents inhibit the phosphorylation of T3 in response to NGF, but have no effect on NGF's ability to cause T1 phosphorylation. In a PC12 mutant deficient in cAMP-dependent protein kinase activity, NGF mediates the phosphorylation of tyrosine hydroxylase on peptide T3 but not on T1. We conclude that NGF mediates the activation of both the cAMP-dependent protein kinase and the C-kinase to phosphorylate substrate proteins. These kinases can act independently to phosphorylate tyrosine hydroxylase, each at a different site, and each of which results in the enzyme activation. A molecular framework is thus provided for events underlying NGF action.

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 Axokinin phosphorylation by cAMP-dependent protein kinase is sufficient for activation of sperm flagellar motility.

1986 ◽  
Vol 103 (2) ◽  
pp. 649-655 ◽  
Author(s):  
J S Tash ◽  
H Hidaka ◽  
A R Means
Keyword(s):  
Protein Kinase ◽  
De Novo ◽  
Protein Kinase Activity ◽  
Dependent Manner ◽  
Flagellar Motility ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Heat Stable ◽  
Protein Kinase N ◽  
Dependent Protein

Using a selective inhibitor of cAMP-dependent protein kinase, N-[2(methylamino)ethyl]-5-isoquinolinesulfonamide (H-8), the requirement for cAMP-dependent phosphoproteins in the initiation of dog sperm flagellar motility was examined. H-8 inhibited motility of live as well as reactivated sperm in a dose-dependent manner. The half-maximal inhibition of reactivated motility (32 microM) paralleled the inhibition of pure catalytic subunit of cAMP-dependent protein kinase (50 microM) measured under the same conditions. H-8 inhibited protein phosphorylation both in whole models and in isolated Nonidet P-40 (NP-40) extracts of sperm. Axokinin, the heat-stable NP-40-soluble protein whose phosphorylation is required for flagellar reactivation, represented 97% of the de novo phosphate incorporation in the NP-40 extract after stimulation by cAMP. 500 microM H-8 inhibited axokinin phosphorylation by 87%. When sperm were reactivated in the presence of up to 5 mM H-8 with NP-40 extract that had been prephosphorylated with cAMP-dependent protein kinase, then neither cAMP nor cAMP-dependent protein kinase activity was required for full flagellar reactivation. If sperm were rendered completely immotile by pretreatment with H-8, then the resulting model remained immotile in the continued presence of H-8 unless prephosphorylated axokinin was added. These results suggest that phosphorylated axokinin is not only required for flagellar reactivation but is sufficient as well.

Cyclic AMP-Dependent Protein Kinase Mediates Glycoprotein Ibα Shedding from Platelet.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3653-3653
Author(s):  
Kesheng Dai ◽  
Rong Yan ◽  
Hong Cheng ◽  
Richard Bodnar ◽  
Changgeng Ruan
Keyword(s):  
Protein Kinase ◽  
Platelet Activation ◽  
Calcium Ionophore ◽  
Platelet Glycoprotein ◽  
Calpain Inhibitor ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Dose Dependent

Abstract Extracellular domain of platelet glycoprotein (GP) Ibα contains ligand binding sites for von Willebrand factor (VWF) and α-thrombin. GPIbα binding to VWF exposed at the injured vessel initiates thrombus formation, thus it plays key roles in thrombosis and hemostasis. While a lot of research has been performed to elucidate the critical roles for GPIbα in platelet activation, little is known about the negative regulatory mechanisms of this adhesion receptor. Here we show that inhibition of cAMP-dependent protein kinase (PKA) resulted in the shedding of GPIbα from platelet. GPIbα was shed after platelets were incubated with PKA inhibitors (H89, PKI) in a dose-dependent manner. PKA mediated GPIbα shedding was inhibited by calpain inhibitors (MDL 28170, E64d, calpain inhibitor-I, calpain inhibitor-II) in a dose-dependent manor, suggesting that shedding of GPIbα is a result of calpain cleavage. Time course experiment revealed that PKA mediated GPIbα shedding occurred as a late event, 10 minutes after platelet activation. Flow cytometry and western-blot data suggested that the cleavage site was at N-terminal of residues 484 and 485 on GPIbα. These residues are responsible for disulfide bond linkage to GPIbβ. Though the size of GPIbα shed fragments from platelet treated with H89 was the same as platelet treated with calcium ionophore A23187 or thrombin, yet the intensity of platelet activation, the amount of GPIbα shedding, and redistribution of GPIbα were different, suggesting that the mechanism of PKA inhibition-initiated GPIbα shedding is different from the shedding caused by A23187 or thrombin. Platelets treated with the PKA inhibitor, H89, presented significant decrease in ristocetin induced platelet aggregation and platelet adhesion on VWF under shear stress. In conclusion, these data provide new evidence that inhibition of PKA results in calpain mediated GPIbα shedding which may play a role in limiting thrombus infinite formation after platelet activation.

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