Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of activation of calcium- and phospholipid-dependent protein kinase (protein kinase C) on human chorionic gonadotropin (hCG) release by cultured trophoblast cells was studied and a role of protein kinase C in the GnRH-mediated hCG release was also evaluated. Both GnRH and 1-oleoyl-2-acetylglycerol (OAG), a protein kinase C activator, stimulated hCG release after 3 h incubation in a dose-dependent manner with ED50 of 55 nmol/l and 4.0 nmol/l, respectively. A tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) also stimulated hCG release while two non-tumor-promoting compounds, phorbol and 4 alpha-phorbol, failed to stimulate hCG release. hCG release by maximal effective dose of GnRH (10 mumol/l) or OAG (1 mumol/l) was further stimulated when cells were incubated with same concentrations of GnRH and OAG. OAG-stimulated hCG release was completely inhibited by a protein kinase C inhibitor, H-7, with ID50 of 23 nmol/l while H-7 did not affect GnRH-mediated hCG release. These results indicate that GnRH-stimulated hCG release is not mediated by protein kinase C pathway, however, the secretion of hCG is also regulated by the mechanism that involves protein kinase C activation.
Placenta
PMID:Effects of diacylglycerol and gonadotropin-releasing hormone on human chorionic gonadotropin release by cultured trophoblast cells. 163 9

Protein kinase C (Ca2+ and phospholipid-dependent protein kinase) was detected in human placenta and was partially purified using DEAE cellulose chromatography and Ultrogel filtration. Diolein alone did not act on this enzyme but exerted a strong stimulatory action when associated with phosphatidylserine and Ca2+. Similar results were obtained with the phorbol myristate acetate. The kinetic constants for ATP, histone HI or Mg2+ and the apparent Ka for Ca2+ and phosphatidylserine were determined.
Placenta
PMID:Isolation and characterization of protein kinase C from human placenta. 215 87

The 30 000 g precipitate of homogenized rat placenta was incubated with 32P-adenosine triphosphate (ATP); several endogenous proteins were specifically phosphorylated in the presence of 0.5 mM calcium and phosphatidylserine (105K protein at mid pregnancy, and 78K protein at the latter part of pregnancy). The calcium- and phospholipid-dependent protein kinase activity in the 30 000 g precipitate was six times greater than the activity in the supernatant fraction. The total protein kinase C activity in the precipitate was considerably greater at the end of pregnancy than it was at mid pregnancy. Diethylaminoethyl cellulose-purified membrane-bound protein kinase C was slightly inhibited by inhibitors of lipoxygenase, NDGA or ETYA, but not by SHAM or BW755C. Haemin and polylysine strongly inhibited this activity.
Placenta
PMID:Phosphorylation of placental membrane proteins by a calcium- and phospholipid-dependent protein kinase. 370 32

The cAMP-dependent and cAMP-independent histone kinases have been studied in the two subcellular compartments (cytosol and particulate fraction) from placentae of different gestational age. The total protein kinase activity, as well as its distribution between the two compartments, changes during the period of gestation. The total activity is significantly increased in full-term placentae. The increase is much greater for the cAMP-dependent (400 per cent), than for the cAMP-independent (270 per cent) protein kinases. It is much higher (400 per cent) in the cytosol than in the particulate fraction (170 per cent); consequently, the particulate fraction of term placentae shows a relatively lower proportion of protein kinase activity (26 per cent of the total activity) than the corresponding fraction of young placentae (37 per cent). DEAE-cellulose chromatography revealed the presence of two cAMP-dependent protein kinase peaks which correspond to Type I and Type II isoenzymes described in many mammalian tissues (Corbin, Keely and Park, 1975). The Type II isoenzyme is predominant in both first- and third-trimester placentae. The increase in protein kinase activity in term placentae is due to the selective activation of the Type II kinase only. The activity of the Type I isoenzyme remained unchanged throughout the period of gestation. The third peak eluted from the DEAE-cellulose column corresponds to a cAMP-independent sucrose-gradient ultracentrifugation into two distinct peaks similar to those already observed in several rat tissues (Toru-Delbauffe, Ohayon and Pavlovic-Hournac, 1983). The protein kinase patterns of both young and term placentae remain stable during the incubation of the tissues 'in vitro' for three hours.
Placenta
PMID:Modification of protein kinase pattern in human placentae during gestation. 609 91

The presence of endogenous modulators of protein kinase C (PKC) in human placenta has not been reported. The specific activity of PKC in human placental cytosol was 20.52 +/- 1.8 pmol/min x mg protein. Partial purification of placental cytosol on diethylaminoethyl cellulose (DEAE) resulted in recovery of 145 per cent of original enzyme activity. Placental cytosol mixed with a control preparation of PKC significantly inhibited the control enzyme activity (control 42.42 +/- 2.8 pmol/min; control+placental cytosol 27.44 +/- 2.8 pmol/min, P < 0.05). The PKC-inhibitory activity was abolished by the addition of phosphatase inhibitors calyculin A (0.09 nM), microcystin LR (0.8 nM), and okadaic acid (0.4 nM). Protein substrates phosphorylated by PKC were rapidly dephosphorylated upon the addition of placental cytosol; this dephosphorylation was prevented by the presence of calyculin A and was removed by fractionation of placental cytosol on DEAE. Protein but not peptide substrate supported both the PKC-inhibitory activity and the dephosphorylation of PKC-phosphorylated substrates. The placental serine-threonine protein phosphatase was active against phosphorylase a, but not against substrate phosphorylated by cAMP-dependent protein kinase. These data indicate that the human placenta contains an endogenous inhibitor of PKC which interacts with substrate rather than with the PKC and that the inhibitor is a protein phosphatase.
Placenta 1994 Oct
PMID:Protein phosphatase activity against protein kinase C-phosphorylated substrates in human placenta. 783 28

In the present study, we investigated the roles of cyclic adenosine monophosphate (cAMP), intracellular calcium, glucocorticoids, protein kinase-C and gonadotrophin-releasing hormone (GnRH) in regulating human chorionic gonadotrophin (hCG), inhibin and activin production in cultured human term placental trophoblast cells. Inhibin and hCG were measured in conditioned media by radioimmunoassay, while putative forms of inhibin and activin were characterized by western blotting using affinity-purified antisera directed against the inhibin alpha- and beta A-subunits. Inhibin and hCG secretion were stimulated by dexamethasone (0.2 microM), GnRH (5-25 microM), calcium ionophore A23187 (0.2-1 microM), phorbol-12-myristate-13-acetate (22 nM) and epinephrine (1 microM), with increasing response over successive 24-h treatment periods. Two molecules Mr approximately 30 and 32 kDa appeared to be the predominant dimeric forms of inhibin secreted by the cells, while 26 kDa activin was present in excess over inhibin. Large amounts of 40-44 kDa protein were detected by the alpha-directed antisera only, which may be a form of the inhibin alpha-subunit precursor protein. Secretion of activin was responsive to phorbol ester-mediated stimulation but not to the presence of GnRH or elevated cAMP concentrations. The divergence in maternal serum inhibin and hCG concentrations during late pregnancy remains unexplained by these findings.
Placenta 1994 Dec
PMID:Comparative regulation of inhibin, activin and human chorionic gonadotropin production by placental trophoblast cells in culture. 788 22

Transforming growth factor-beta (TGF-beta) and activin-A, two members of a ubiquitous family of regulators of growth, differentiation and hormonogenesis, are produced by the human placenta. Their effects on placental hCG, inhibin, and oestrogen production in vitro, either alone or in combination, were investigated using cultured Percoll-purified placental trophoblasts. Inhibin and hCG were measured by immunoassay, while aromatase activity (i.e. oestrogen production) was measured using the tritiated water method. Aromatase activity and production of hCG, but not inhibin, were inhibited (up to approximately 30 per cent) in a dose-dependent fashion by 48 h treatment with TGF-beta. The effects were significant at all doses tested, from 0.1-10 ng/ml. In contrast, activin stimulated hCG production and aromatase activity over the doses tested (0.25-25 ng/ml). The maximum effect (approximately 50 per cent stimulation above control) was seen at the 2.5 ng/ml dose, with lesser effects seen at the lower and higher doses. This characteristic bell-shaped dose-response curve was maintained in the presence of TGF-beta (10 ng/ml) or a maximally-effective dose of forskolin (6.7 microM). This suggests that the actions of activin were independent of those of TGF-beta, and were not mediated by the protein kinase-A pathway. Activin had a weak stimulatory effect on inhibin production. The results indicate that in the placenta activin and TGF-beta have opposing actions on hormonogenesis. Both factors may play a role in regulating placental function and the timing and progression of labour.
Placenta 1996 Nov
PMID:Activin-A stimulates, while transforming growth factor beta 1 inhibits, chorionic gonadotrophin production and aromatase activity in cultured human placental trophoblasts. 891 9

The env region of the human endogenous retrovirus ERV-3 is expressed during differentiation of trophoblast and the choriocarcinoma BeWo. Stable transfectants with ERV-3 env exhibit most aspects of trophoblast differentiation, including inhibition of cell proliferation, changes in cell morphology, and increased production of beta-hCG mRNA. In this study, the cellular mechanism of induction of BeWo cell differentiation by ERV-3 env was investigated. In BeWo cells stably transfected with ERV-3 env, the production of beta-hCG mRNA and hCG protein was increased. Intracellular cAMP level was markedly increased over that of vector transfected cells. The effect on beta-hCG protein production was inhibited by H89, a protein kinase A (PKA) inhibitor, while protein kinase C (PKC) and protein tyrosine kinase (PTK) inhibitors had no effect. The expression of a major cell cycle promoter, cyclin B, was markedly reduced while expression of p21, a negative regulator of the cell cycle, was up-regulated. Inhibition of ERV-3 env induced hCG production with H89 had no significant effect on cell growth when compared with cells transfected with vector alone.
Placenta 2000 Jan
PMID:The cellular mechanism by which the human endogenous retrovirus ERV-3 env gene affects proliferation and differentiation in a human placental trophoblast model, BeWo. 1069 54

Foetal membrane rupture is thought to follow from gene-controlled tissue remodelling and apoptosis. We reported previously that staurosporine, cycloheximide, actinomycin D, as well as more physiological apoptotic agents (lactosylceramide, 15d-PGJ(2)) increase prostaglandin release in parallel with induction of apoptosis in WISH and amnion epithelial cells. Also, inhibition of prostaglandin release by cyclooxygenase inhibitors or PKA activators is accompanied by a parallel decrease in apoptosis. We hypothesize that amnion prostaglandin metabolism is linked with apoptosis in amnion epithelial cells and thus to membrane rupture. Amnion mesenchymal cells are also critical for membrane integrity. Their susceptibility to apoptotic agents is unknown and is the subject of this report. In amnion epithelial cells, lactosylceramide (125 microM) induced 6.5-fold, 20-fold increases in PGE(2) and NMP production (apoptosis), respectively. Conversely, in mesenchymal cells, lactosylceramide doses up to 200 microM had no effect on PGE(2) or NMP release. In both cell types, incubation with 15d-PGJ(2) (5-100 microM) demonstrated dose and time dependent increases in PGE(2) and NMP. PKA activators inhibited 15d-PGJ(2) induced PGE(2) release and apoptotis in epithelial cells, but not in mesenchymal cells, however. Major amnion cell types have different sensitivities to physiological apoptotic agents. Prostaglandin release occurs coincident with apoptosis in both amnion epithelial and mesenchymal cells.
Placenta
PMID:Physiological apoptotic agents have different effects upon human amnion epithelial and mesenchymal cells. 1256 44

Villous trophoblasts undergo increased apoptosis and experience a wider gradient of oxygen tensions (pO(2)) in pregnancies complicated by intrauterine growth restriction. We hypothesize that pO(2)affects trophoblast apoptosis by altering survival signalling through the phosphatidylinositol-3 (PI-3)-kinase and mitogen activated protein kinase (MAPK) pathways. Cytotrophoblasts were cultured at pO(2)from <10 to approximately 140 mmHg with Epidermal Growth Factor (EGF), Vascular Endothelial Growth Factor (VEGF) and basic Fibroblast Growth Factor (bFGF) at concentrations of 0.1 to 10 ng/ml for 1 to 12 h, then assessed for apoptosis (TUNEL) and specific protein expressions (Western blot analysis). Spontaneous apoptosis was highest at <10 mmHg and lowest approximately 15 mmHg. Only EGF activated either signalling pathway at any pO(2). Inhibition of both pathways was required to inhibit EGF-stimulated survival. Maximal EGF activation of either pathway was insensitive to pO(2). At lower oxygen tensions, MAPK phosphorylation was maximal at 1 ng/ml EGF compared with 10 ng/ml for the PI-3-kinase path. The EGF receptor was spontaneously phosphorylated with increasing culture times at lower oxygen levels, an effect reflected down-stream by PI-3-kinase and Akt phosphorylation. We conclude that strong survival signalling in trophoblasts requires both PI-3- and MAP-kinase pathways, is rather insensitive to pO(2)changes and is spontaneously activated with increasing hypoxic exposure.
Placenta 2003 Jul
PMID:The effect of oxygen tension on intracellular survival signalling in primary villous trophoblasts. 1282 21


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