Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Conditions were established for the primary culture of guinea-pig tracheal smooth muscle cells, the identity of which was confirmed by the presence of smooth muscle alpha-actin by western blotting. Cells were preincubated with [3H]palmitate which was incorporated, almost exclusively, into phosphatidylcholine. When these cells were stimulated by either bradykinin or phorbol 12-myristate 13-acetate (PMA), in the presence of butan-1-ol, the non-metabolizable product [3H]phosphatidylbutanol ([3H]PtdBut) accumulated by virtue of the phosphatidyltransferase activity of phospholipase D. The activation of phospholipase D by bradykinin was inhibited by 86 +/- 11% (N = 3 experiments) in the presence of the protein kinase C inhibitor, staurosporine (1 microM) and by 88 +/- 11% (N = 3 experiments) in cells that had been chronically treated with PMA to down-regulate their protein kinase C. PMA-stimulated phospholipase D was similarly affected (92 +/- 2% inhibited by staurosporine, 87 +/- 6% inhibited by protein kinase C down-regulation). Removal of extracellular Ca2+ markedly reduced the bradykinin-stimulated phospholipase D response (by 73 +/- 10%, N = 3 experiments) but had only a limited effect upon PMA-stimulated phospholipase D activity (by 23 +/- 6%, N = 3 experiments). [AIF4](-)-stimulation of the cells also resulted in the activation of phospholipase D, indicating the involvement of a G-protein. However, this was not Gi since pertussis-toxin pretreatment of the cells failed to abolish either bradykinin-stimulated inositol (1,4,5)trisphosphate formation or [3H]PtdBut accumulation. Western blotting revealed the presence of Gq/G11 which couples to the inositol lipid-directed phospholipase C. Indomethacin (10 microM) was without effect upon bradykinin-stimulated phospholipase D activity, suggesting that the bradykinin effects were not mediated indirectly by cyclooxygenase products. The role of phospholipase D activation in tracheal smooth muscle may be to, indirectly, produce diacylglycerol for the activation of protein kinase C which has been implicated in sustained contraction. However, the immediate product of phospholipase D, phosphatidate, has been proposed to have a number of second messenger roles and may itself, by an undefined mechanism, be involved in the sustained contraction of airway smooth muscle.
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PMID:Bradykinin stimulates phospholipase D in primary cultures of guinea-pig tracheal smooth muscle. 844 59

Interleukin-1 beta (IL-1) stimulates by about fivefold NGF secretion from rat neonatal cortical astrocytes in primary culture. We investigated the possible intracellular second messenger mechanisms involved in the IL-1 induced NGF secretion. Basal NGF secretion did not require extracellular Ca2+, whereas Ca2+ was necessary for the maximal NGF secretion stimulated by IL-1 (10 units/ml). The protein kinase C activator TPA stimulated by sixfold NGF secretion, but in this case, TPA acted synergistically with IL-1 to increase NGF secretion. Treatment of cells with the phospholipase A2 inhibitor mepacrine (30 microM) inhibited basal (by 50%) and IL-1 stimulated (by 80%) NGF secretion. Indomethacin, a cyclooxygenase inhibitor, produced a slight increase in basal NGF secretion at low concentrations, while PGE2 (10 microM) inhibited basal and IL-1 stimulated NGF secretion. In contrast, treatment of cells with nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, blocked in a concentration-dependent manner (IC50 = 10 microM) IL-1 stimulation of NGF secretion. The leukotriene LTB4 increased basal NGF secretion and this effect was not additive with IL-1 when both agents were added at saturating concentrations, indicating a common mechanism of action for these two agents. Thus, one possible mechanism by which IL-1 stimulates NGF secretion from astrocytes is by activation of the phospholipase A2-lipoxygenase pathway.
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PMID:Arachidonic acid lipoxygenation may mediate interleukin-1 stimulation of nerve growth factor secretion in astroglial cultures. 845 May 66

Arachidonic acid (AA) is a precursor of metabolites known to affect the corpus luteum (CL) in many species, including primates. We have shown that some of these products (prostaglandins F2 alpha and E2) inhibit pro-gesterone (P4) production and activate the phosphatidylinositol (PI) pathway in CL of rhesus monkeys. A direct role of AA in luteal function has also been suggested. The current experiments were designed to investigate the effect of AA on P4 synthesis and to examine the ability of AA to activate the PI pathway in CL of rhesus monkeys. Basal and hCG-stimulated P4 production by luteal cells collected during the midluteal phase was measured after treatment with AA (1, 5, and 10 microM) or linoleic acid (1, 5, and 10 microM). Dispersed cells (50,000/tube) were incubated at 37 degrees C for 2 h. AA elicited a dose-dependent decrease in hCG-stimulated, but not in basal, P4 production. hCG-stimulated P4 production was reduced (P < 0.01) at AA doses of 5 microM (12.1 +/- 1.5 ng/mL) and 10 microM (8.6 +/- 1.8 mg/mL) to hCG alone (18 +/- 1.6 ng/mL). There was no significant effect of 1 microM AA (15.2 +/- 1.6). Response to linoleic acid was dissimilar and was not dose-dependent. Viability of cells was not affected by any treatment. Indomethacin, a prostaglandin synthesis inhibitor, and nordihydroguaiaretic acid, an inhibitor of lipoxygenase, did not interfere with the inhibitory effect of AA. Activation of the PI pathway was assessed by monitoring the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2) to inositol phosphates and by monitoring increases in intracellular free calcium concentrations ([Ca2+]i) in individual cells. Moreover, the ability of AA to activate protein kinase C (PKC) in luteal cells was measured using a [3H]phorbol dibutyrate (PDBu) binding assay. AA did not alter PIP2 hydrolysis or [Ca2+]i, however, AA (10 microM) increased specific binding of [3H]PDBu to luteal cells (P < 0.05). We conclude that AA inhibits hCG-stimulated P4 production by primate luteal cells. AA exerts this action without being converted to prostaglandins or leukotrienes. This inhibition may be mediated through the activation of PKC. These results suggest a possible role for AA in the regulation of luteal function in primates, and that PKC-activation by AA may promote its effects.
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PMID:Arachidonic acid inhibits hCG-stimulated progesterone production by corpora lutea of primates: potential mechanism of action. 858 72

Experiments were carried out at different times of hibernation to ascertain whether prostaglandin is produced by Rana ovarian follicles during gonadotropin- or 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced in vitro ovulation. Ovarian fragments were cultured in amphibian Ringer in the presence or absence of frog pituitary homogenate (FPH, 0.05 gland/ml) or TPA (1 or 10 microM). After various periods of culture, incidence of ovulation was determined and prostaglandin F2 alpha (PGF2 alpha) accumulated in culture medium was measured by radioimmunoassay. FPH and TPA increased PGF2 alpha levels in medium in a dose-dependent manner. The time course of PGF2 alpha secretion and ovulation by FPH or TPA treatment varied during the hibernation period. In early-hibernation, FPH stimulated neither PGF2 alpha secretion nor ovulation while TPA stimulated PGF2 alpha secretion, although it failed to induce ovulation. In mid-hibernation, FPH and TPA effectively stimulated PGF2 alpha secretion and ovulation, but both events took place several hours later than those observed in late-hibernation. Some fragments obtained in mid-hibernation and most obtained in late-hibernation spontaneously produced PGF2 alpha in vitro without FPH or TPA treatment and in some instances spontaneously ovulated. Furthermore, FPH or TPA increased PGF2 alpha levels further or accelerated the time course of secretion by such fragments. In late-hibernation, PGF2 alpha secretion induced with FPH or TPA increased simultaneously with or later than onset of ovulation. Exogenous cAMP (2.5 mM) or 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7, 100 microM), a PKC inactivator, markedly suppressed FPH- or TPA-stimulated PGF2 alpha secretion and ovulation in mid-hibernation. Indomethacin (IM, 5 micrograms/ml) strongly suppressed TPA- or FPH-stimulated PGF2 alpha production by fragments but its effect on ovulation varied among animals and at different times. IM suppressed ovulation of some ovarian fragments obtained in mid-hibernation, but failed to suppress hormone-induced ovulation in late-hibernation. Cycloheximide (5 micrograms/ml) and actinomycin D (1 microgram/ml) effectively suppressed FPH-stimulated PGF2 alpha production and ovulation, whereas actinomycin D reduced but failed to significantly suppress TPA-induced PGF2 alpha production in mid-hibernation. In general, effects of ovulation inhibitors exhibited strong seasonal variations and were less efficient as the breeding season approached. Taken together, the data suggest that elevated levels of PGF2 alpha are associated with spontaneous and hormone-induced ovulation, and PKC mediates gonadotropin induction of PGF2 alpha but not steroid synthesis in Rana ovaries.
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PMID:Prostaglandin production and ovulation during exposure of amphibian ovarian follicles to gonadotropin or phorbol ester in vitro. 877 52

Prostaglandin E2 (PGE2) levels are elevated in malignant human breast tissue. However, the cellular mechanisms regulating this arachidonate metabolism and the autocrine influence PGE2 production may have on breast cancer cell growth and function are unclear. In the present study, we have investigated the effects of 2 putative cyclo-oxygenase inducers, interleukin-1beta (IL-1beta) and the protein kinase C agonist 12-O-tetradecanoyl-phorbol-13-acetate (TPA), on PGE2 production, growth and aromatase activity in the MDA MB 231 breast cancer cell line. TPA stimulated a dose-dependent increase in PGE2 production, inhibited cell growth and stimulated aromatase activity. Although IL-1beta alone had no effect on any of these breast cancer cell functions, the cytokine greatly potentiated PGE2 production in the presence of TPA. Similarly, growth inhibition and aromatase stimulation in response to TPA were both further enhanced by IL-1beta treatment. Indomethacin and dexamethasone both prevented PGE2 production in response to IL-Ibeta and TPA but had no effect on the anti-proliferative action of the cytokine and phorbol ester. While indomethacin had no effect on induction of aromatase activity by IL-1beta and TPA, dexamethasone exhibited a temporally biphasic action. Dexamethasone alone stimulated aromatase activity and demonstrated a permissive action on aromatase stimulation by IL-1beta and TPA. However, pre-treatment of cells with dexamethasone prevented subsequent induction of aromatase activity by IL-1beta and TPA. Our study describes a novel synergistic interaction in response to protein kinase C activation and IL-1beta during the regulation of arachidonate metabolism, cell growth and aromatase activity in human breast cancer cells. We conclude that the cyclooxygenase pathway does not play a mediatory role during the inhibition of cell growth and the induction of aromatase activity by IL-1beta and TPA.
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PMID:Regulation of arachidonic acid metabolism, aromatase activity and growth in human breast cancer cells by interleukin-1beta and phorbol ester: dissociation of a mediatory role for prostaglandin E2 in the autocrine control of cell function. 878 59

We have previously identified expression of multiple protein kinase C (PKC) isoforms in insulinoma-derived beta-cells and whole islets. Both PKC delta and PKC alpha appear to be the more abundantly expressed isoforms. In this report we studied the effects of arachidonic acid (AA) on the subcellular distribution of PKC alpha and PKC delta. AA has been reported to activate both PKC alpha and PKC delta and it is thought to be an important second messenger in beta-cells. Here we report that AA interacted with and altered beta-cell pools of PKC delta preferentially over PKC alpha. AA (100 microM) over the course of 45 min reduced cytosolic levels of PKC delta (to 40 +/- 15%, compared to time zero control) leaving membrane- and cytoskeleton-associated levels near control levels. Analysis of whole cell homogenates showed a slight down-regulation of PKC delta indicating proteolysis. The down-regulation of cytosolic PKC delta appeared to be isoform specific since cytosolic PKC alpha remained at control levels over the time course. The response was dose-dependent and negligible at concentrations below 30 microM and occurred, at least partially, in the cytosolic compartment of the cell. Indomethacin also down-regulated cytosolic PKC delta preferentially over PKC alpha possibly through accumulation of AA. These findings suggest that cytosolic PKC delta may be a downstream target of this beta-cell second messenger.
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PMID:Arachidonic acid-induced down-regulation of protein kinase C delta in beta-cells. 889 99

The involvement of protein kinase C (PKC) and protein tyrosine kinase (PTK) in hypercapnia-induced cerebral vasodilation in newborn pigs was investigated with closed cranial windows using the PKC stimulator phorbol 12-myristate 13-acetate (PMA), and the PTK inhibitors, genistein and herbimycin A. The influence of prostaglandin I2 was eliminated using the prostaglandin cyclooxygenase inhibitor, indomethacin. Changes in pial arteriolar diameters in response to hypercapnia [partial pressure of arterial CO2 approximately 9.3 kPa (70 torr)] were analyzed. Genistein (40 micrograms/mL), herbimycin A (10 microM), or PMA (1 microM) did not affect cerebral vasodilation to hypercapnia when applied topically. Indomethacin (5 mg/kg i.v.) treatment blocked the dilation to hypercapnia and attenuated hypercapnia-induced increase in cortical cAMP. Genistein and herbimycin A restored the response to hypercapnia to indomethacin-treated piglets. PMA also restored the pial arteriolar dilation and the cAMP response to hypercapnia to indomethacin-treated piglets. One-hour exposure to 10 microM PMA, to down-regulate PKC, blocked vasodilation to hypercapnia but did not inhibit vasodilation to sodium nitroprusside. After prolonged (2 h) topical exposure of indomethacin-treated piglets to 10 microM PMA, neither genistein nor iloprost could restore dilation to hypercapnia. These results indicate that PKC stimulation and/or PTK inhibition may permit hypercapnia-induced vasodilation. These data further suggest that PKC is downstream from PTK in the regulatory pathway. Because previous data showed prostaglandin I2 at subdilator concentrations can also return dilation to hypercapnia to piglets treated with indomethacin, prostaglandin I2 could provide its permissive input by activating PKC and/or inhibiting PTK.
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PMID:Protein kinase Cs and tyrosine kinases in permissive action of prostacyclin on cerebrovascular regulation in newborn pigs. 897 94

Developmental changes in the effects of arachidonic acid (AA) on N-methyl-D-aspartate (NMDA) receptor-mediated currents were investigated in acutely dissociated rat cortical neurones using a whole-cell patch-clamp method. AA potentiated peak NMDA currents (INMDA) in a concentration-dependent manner. Potentiation by AA was greater at 2-4 postnatal days (P2-4) than at P7-8 and P15-18. Indomethacin reduced the potentiating effect of AA only at P2-4, while caffeic acid and baicalein showed no apparent effect, indicating that metabolites of the cyclooxygenase pathway contribute to INMDA potentiation at P2-4. Staurosporine diminished the potentiation of INMDA at P2-4, suggesting that protein kinase C might participate in the effect of AA. These findings suggest that the greater potentiation of INMDA by AA at P2-4 has a different underlying mechanism from effects seen at P7-8 or older.
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PMID:Developmental changes in arachidonic acid potentiation of NMDA currents in cortical neurones. 898 4

The present study aimed to investigate the possible role of endothelium in contractile response to phorbol 12,13-diacetate (PDA) by measuring the contractile force in rat isolated aortic rings. PDA at low concentrations induced small and sustained tension in arteries with intact endothelium. N(G)-Nitro-L-arginine (100 microM), a nitric oxide synthase inhibitor and methylene blue (10 microM), an O2-generator induced a large increase in tension in the presence of PDA. The magnitude of contractions in response to N(G)-Nitro-L-arginine was related to concentrations of PDA. Staurosporine (10 nM), an inhibitor of protein kinase C completely inhibited contractile response to PDA as well as potentiating effects of N(G)-Nitro-L-arginine and methylene blue. Removal of the endothelium abolished contractile responses to both N(G)-Nitro-L-arginine and methylene blue in the presence of PDA. Removal of extracellular Ca2+ suppressed contractile responses to both PDA and N(G)-Nitro-L-arginine. On the other hand, N(G)-Nitro-L-arginine (100 microM) did not induce contractions of the rat aorta pre-treated with 4-alpha-phorbol 12-myristate 13-acetate, an inactive form of phorbol ester. Acetylcholine concentration-dependently induced reduction of tension induced by PDA (0.3 microM) in rat aorta. N(G)-Nitro-L-arginine or removal of endothelium prevented the effect of the acetylcholine-induced relaxation. Indomethacin (1 microM), glibenclamide (3 microM) and charybdotoxin (100 nM) did not affect the PDA response in rat aorta. These results indicate that in rat aorta, the basal release of nitric oxide could modulate the PDA-induced contraction, which is likely to accounts for the smaller contractile response induced by PDA in arteries with intact endothelium compared to much larger contractions seen in arteries without endothelium.
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PMID:Influence of endothelium in contraction induced by phorbol ester in isolated rat aortic rings. 915 Apr 14

We have previously shown that angiotensin II (AII) potentiates responses evoked by endothelin-1 (Et-1). In the present study, the additional ability of hypoxia or phorbol 12, 13-dibutyrate (PDBu) to evoke hyperreactivity was examined. In addition, the role of cyclooxygenase and 5-lipoxygenase metabolites of arachidonic acid in the potentiation evoked by AII, hypoxia or PDBu was studied, using indomethacin and nordihydroguaiaretic acid (NDGA). The involvement of protein kinase C in the enhanced response was examined using staurosporine. Contractions were measured isometrically from rings of bovine bronchi. Contractions evoked by Et-1 alone were unaltered by indomethacin (10(-6)M), NDGA (10(-5)M) or staurosporine (3 x 10(-8)M). AII (3 x 10(-7)M), hypoxia (4% O2) or PDBu (10(-8)M) each significantly potentiated the contractions evoked by Et-1. Indomethacin (10(-6)M) virtually abolished the effect of AII, hypoxia or PDBu. NDGA (10(-5)M) reversed the potentiating effect of both AII and hypoxia and partially reversed PDBu-evoked enhancement of Et-1-mediated responses. Staurosporine (3 x 10(-8)M) abolished the ability of AII or PDBu, but not hypoxia, to enhance Et-1-mediated contractions. In conclusion, AII, hypoxia and PDBu evoke hyperresponsiveness which is mediated by prostanoids and/or leukotrienes, the precise nature of which remains to be elucidated. Differences in the ability of staurosporine to reverse AII- and hypoxia-induced hyperreactivity suggests, however, that these conditions may generate different eicosanoids.
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PMID:The role of cyclooxygenase and 5-lipoxygenase metabolites in potentiated endothelin-1-evoked contractions in bovine bronchi. 916 Apr 8


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