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)

The regulation of phosphatidylcholine (PtdCho) hydrolysis by Ca2+ and protein kinase C (PKC) was measured in [3H]palmitate-labelled cultured guinea-pig airway smooth-muscle cells as phosphatidylbutanol ([3H]PtdBut) and phosphatidate ([3H]PtdOH) formation in the presence of butanol. The former is a direct measure of phospholipase D (PLD) activity, whereas the latter, in airway smooth muscle, is indicative of net PtdCho-specific phospholipase C (PLC)-like/diacylglycerol (DG) kinase activity. Bradykinin-stimulated responses exhibited a requirement for extracellular Ca2+ influx, since they were inhibited in the presence of EGTA. This influx was independent of voltage-operated channels, since the L-type channel blocker nifedipine (up to 10 microM) was without effect on bradykinin-stimulated responses. In support of this, membrane depolarization with KCl (30 mM) failed to elicit either response. However, bradykinin-stimulated formation of both [3H]PtdBut and [3H]PtdOH was partially inhibited by 100 microM SKF96365. Ionomycin, a Ca2+ ionophore, induced PtdCho hydrolysis to a greater extent than bradykinin, also in an extracellular-Ca(2+)-dependent manner. Thapsigargin-induced emptying of intracellular Ca2+ pools elicited the formation of both [3H]PtdBut and [3H]PtdOH and displayed a requirement for extracellular Ca2+. Bradykinin-stimulated PtdCho-specific PLC-like/DG kinase pathway and PLD responses were unaffected by thapsigargin pretreatment, thereby questioning the role of Ins(1,4,5)P3/Ins(1,3,4,5)P4-dependent Ca2+ stores in the receptor stimulation of these activities in airway smooth-muscle cells. In this regard, we have previously demonstrated that the bradykinin-stimulated PtdCho-specific PLD and PLC-like activities can occur under conditions of apparent complete blockade of bradykinin-stimulated Ins(1,4,5)P3 formation by receptor antagonist in guinea-pig airway smooth muscle. The PKC inhibitor, Ro31-8220, selectively blocked both bradykinin- and ionomycin-stimulated PLD activity in a concentration-dependent manner (IC50 approx. 1 microM), but was without effect on bradykinin-stimulated PtdCho-PLC-like/DG kinase-derived PtdOH formation. In contrast, an inhibitor of PtdCho-PLC, D609, selectively blocked the formation of [3H]PtdOH in the presence of butanol (PtdCho-PLC-like/DG kinase activity), but not [3H]PtdBut formation. In conclusion, PtdCho hydrolysis appears to occur via two distinguishable routes which both require extracellular Ca2+, whereas only the PLD route is regulated by PKC.
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PMID:Bradykinin-stimulated phosphatidylcholine hydrolysis in airway smooth muscle: the role of Ca2+ and protein kinase C. 748 7

This study examined the mechanistic basis of the synergistic interaction between the cyclic AMP (cAMP) and phosphoinositide pathways in salivary amylase secretion. cAMP produced a concentration-dependent increase in Ca++ mobilization from saponin-permeabilized rat parotid acinar cells. A threshold concentration of cAMP (50 microM) significantly increased the peak Ca(++)-releasing activity of submaximal concentrations of inositol 1,4,5-trisphosphate (IP3) but did not augment the Ca++ mobilization induced by a maximal stimulating concentration of IP3 (30 microM). A maximal stimulating concentration of cAMP (500 microM) failed to modify the Ca++ releasing action of IP3. IP3-induced Ca++ release was also augmented by catalytic subunit of cAMP-dependent protein kinase. A specific protein kinase inhibitor reversed this effect. The cAMP-induced Ca++ release was blocked by ryanodine but not by heparin, by contrast with the IP3-induced Ca++ release. Thapsigargin only partially depressed the cAMP response but completely abolished the IP3 response. The amylase release elicited by fixed concentrations of Ca++ was not further enhanced by either cAMP or forskolin. Thus, unlike diacylglycerol, which decreases the Ca++ requirement for secretion by inducing activation of protein kinase C, cAMP appears to mediate salivary amylase secretion by regulating the sensitivity of parotid cells to the Ca++ mobilizing action of IP3. In addition, cAMP possesses a second action, i.e., directly eliciting Ca++ mobilization from an IP3-insensitive pool.
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PMID:Cyclic AMP regulation of calcium mobilization and amylase release from isolated permeabilized rat parotid cells. 750 90

The control of inositol phosphate (IP) turnover was investigated in intact human airway smooth muscle cells (SMC) during a brief exposure to a bronchoconstrictor agonist. The pool of membrane phosphatidylinositol 4,5-biphosphate was labelled by incubating SMC with myo-[3H]inositol and the [3H]IPs synthetized ([3H]1,4-IP2, [3H]1,3,4,-IP3, [3H]1,4,5,-IP3 and [3H]1,3,4,5-IP4) were separated by HPLC. We examined the role of protein kinase C (PKC) and of Ca2+ on IP turnover during a 5 sec application of histamine. Activation of PKC with the phorbol ester PMA (0.2 microM) decreased, whereas inhibition of PKC with 1 microM staurosporine increased the production of the 4 IPs examined in unstimulated and in histamine-stimulated SMC. Decreasing [Ca2+]i with 5 microM ionomycin in the absence of external Ca2+ diminished the IP production whereas in the presence of Ca2+, ionomycin exalted it and potentiated the response to histamine. Thapsigargin, 5 microM, which depletes the 1,4,5-IP3-sensitive Ca2+ stores, reduced the IP production due to histamine. The effects of PMA, staurosporine and thapsigargin were also tested on [Ca2+]i in fura-2-loaded single SMC. These results reveal that PKC exerts a negative and Ca2+ a positive feedback control on phospholipase C, that operate within 5 sec of agonist stimulation.
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PMID:Control of inositol phosphate turnover in human airways during histamine stimulation. 753 40

Primary astrocytic cultures derived from day-15 chick embryo (E15) cerebral hemispheres (CH) or cerebellum (CB) express a calcium/phospholipid-dependent isoform as the major protein kinase C (PKC-alpha/beta). PKC was activated (translocation of activity from cytosol to membrane) following stimulation with carbachol, so we tested for activation of phospholipase C (PLC) as the source of diacylglycerol released from polyphosphoinositide (PIP2) hydrolysis. Carbachol activated PLC (inositol phosphate release) 4-fold in a time- and dose-dependent manner in cortical (CH) astrocytes, but there was no activation of PLC in astrocytes from cerebellum (CB). Pirenzepine, but not gallamine, attenuated both carbachol-induced PKC translocation and PIP2 hydrolysis in E15CH astrocytes, arguing for contribution of M1 subtype. The phorbol ester TPA completely inhibited PIP2 hydrolysis, both basal and carbachol-stimulated, and elicited a stronger, but shorter (10 min) activation of PKC than that observed with carbachol. We investigated phospholipase D (PLD) activation as an alternate source of diacylglycerol in astrocytes, since the ratio of PLC to PKC activation by carbachol was lower in astrocytes than observed in neurons. We observed a dramatic (10-fold) time- and dose-dependent activation of PLD by TPA in CH and a 3-fold increase in CB. The duration of TPA-dependent PLD activation correlated well with increased cell proliferation and changes in astrocytic phenotype markers. Carbachol-stimulated PLD activation was observed in CH but not in CB astrocytes, being mostly dependent on the M3 receptor subtype in the former. In contrast, glutamate elicited a greater PLD activation in CB astrocytes, than in CH astrocytes. TPA activation of PLD was totally blocked by staurosporine (PKC inhibitor) and genistein (a tyrosine kinase inhibitor) in cerebellar (CB) astrocytes; however, total inhibition of TPA-dependent PLD activation was only achieved in cortical (CH) astrocytes after addition of EGTA. Thapsigargin activated PLD in both populations, further emphasizing the PLD activation dependency on [Ca2+]i. Taken together with our previous observations that TPA induces proliferation, cytoskeleton changes, and decreases of glutamine synthetase activity, these data suggest that phospholipase D is a differential but important participant in the regulation of the signalling of mitosis and differentiation in astrocytes during their development.
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PMID:Differential regulation of phospholipases C and D by phorbol esters and the physiological activators carbachol and glutamate in astrocytes from chicken embryo cerebrum and cerebellum. 755 28

Thapsigargin (TG), an inhibitor of Ca(2+)-ATPase, depletes intracellular Ca2+ stores and induces a sustained Ca2+ influx without altering phosphatidyl inositol levels. TG plus phorbol myristate acetate (PMA) but not TG alone induced IL-2 in Jurkat T cells, suggesting that TG had no effect on protein kinase C (PKC). However, TG induced increases in IL-2R alpha protein as well as IL-2R alpha mRNA in Jurkat T cells in a dose-dependent manner. A similar increase in IL-2R alpha by TG was also observed in human peripheral T cells. Further, like PMA, TG markedly induced NF kappa B in Jurkat T cells. However, TG and PMA exhibited a synergistic action on IL-2R alpha expression, suggesting that TG and PMA induce IL-2R alpha through distinct pathways. PMA- but not TG-induced IL-2R alpha is inhibited by the PKC inhibitor H7, whereas TG- but not PMA-induced IL-2R alpha was inhibited by cholera toxin, forskolin and 1,9-dideoxy forskolin. In toto, these results suggest that TG induces IL-2R alpha in human T cells through a PKC-independent pathway.
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PMID:Thapsigargin induces IL-2 receptor alpha-chain in human peripheral and Jurkat T cells via a protein kinase C-independent mechanism. 762 91

Histamine is a known chromaffin cell secretagogue that induces Ca(2+) -dependent release of catecholamines. However, conflicting evidence exists as to the source of Ca2+ utilized in histamine-evoked secretion. Here we report that histamine-H1 receptor activation induces redistribution of scinderin, a Ca(2+)-dependent F-actin severing protein, cortical F-actin disassembly, and catecholamine release. Histamine evoked similar patterns of distribution of scinderin and filamentous actin. The rapid responses to histamine occurred in the absence of extracellular Ca2+ and were triggered by release of Ca2+ from intracellular stores. The trigger for the release of Ca2+ was inositol 1,4,5-trisphosphate because U-73122, a phospholipase C inhibitor, but not its inactive isomer (U-73343), inhibited the increases in IP3 and intracellular Ca2+ levels, scinderin redistribution, cortical F-actin disassembly, and catecholamine release in response to histamine. Thapsigargin, an agent known to mobilize intracellular Ca2+, blocked the rise in intracellular Ca2+ concentration, scinderin redistribution, F-actin disassembly, and catecholamine secretion in response to histamine. Calphostin C and chelerythrine, two inhibitors of protein kinase C, blocked all responses to histamine with the exception of the release of Ca2+ from intracellular stores. This suggests that protein kinase C is involved in histamine-induced responses. The results also show that in the absence of F-actin disassembly, rises in intracellular Ca2+ concentration are not by themselves capable of triggering catecholamine release.
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PMID:Histamine-evoked chromaffin cell scinderin redistribution, F-actin disassembly, and secretion: in the absence of cortical F-actin disassembly, an increase in intracellular Ca2+ fails to trigger exocytosis. 764 7

Extracellular application of ATP and ADP evoked the oscillatory K+ currents (IKCa) resulting from the periodic rise in cytoplasmic Ca2+ concentration ([Ca2+]i) of megakaryocyte isolated from rat bone marrow (Uneyama, H., Uneyama, C., and Akaike, N. (1992) Jpn. J. Pharmacol. 58, 231). The intracellular mechanism of ATP-induced cytoplasmic Ca2+ oscillation was investigated by the use of nystatin-perforated patch-clamp technique. Caffeine and ryanodine, which release Ca2+ from the Ca(2+)-induced Ca2+ release pool (CICR), and procaine, a blocker of Ca2+ release from CICR, had no effect on the IKCa oscillation in megakaryocyte. Thapsigargin and A23187 activated IKCa irreversibly by mobilizing Ca2+, but under Ca(2+)-free conditions they activated IKCa transiently. Intracellular application of inositol 1,4,5-triphosphate (IP3) also induced IKCa oscillation. Phorbol myristate acetate (PMA), a strong activator of protein kinase C (PKC), inhibited the oscillation completely. The inhibitory action of PMA was reversed by an inhibitor of PKC, staurosporin. The oscillation of ATP-induced IKCa was disrupted by staurosporin or calmodulin (CaM) antagonists such as W-7 and trifluoperazine, resulting in a transient and successive plateau-like IKCa. These results suggest that Ca2+ oscillation in megakaryocyte is caused by the interaction of both the Ca2+ release from IP3-sensitive Ca2+ pool and the Ca2+ uptake stimulated by PKC and Ca2+/CaM complex. Furthermore, forskolin, an activator of adenylate cyclase, and isobutylmethylxanthin, an inhibitor of phosphodiesterase, inhibited the frequency, latency, and current amplitude of the oscillation in a concentration-dependent manner. These reagents inhibited IP3-induced oscillation as well as an ATP-induced oscillation. Thus, the ATP-induced [Ca2+]i oscillation of rat megakaryocyte is also modulated by cAMP.
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PMID:Intracellular mechanisms of cytoplasmic Ca2+ oscillation in rat megakaryocyte. 767 93

The specific inhibitors of the endoplasmic reticulum Ca2+ pump, thapsigargin and 2,5-di-tert-butylhydroquinone (DBHQ), stimulated reinitiation of DNA synthesis in synergy with either phorbol 12,13-dibutyrate or bombesin in Swiss 3T3 cells. Maximum stimulation was achieved at 0.5 nM thapsigargin and 7.5 microM DBHQ. Kinetics of [3H]thymidine incorporation were consistent with exit from G0 and entry into S phase. Autoradiography of labeled nuclei showed that the increase in [3H]thymidine incorporation was due to an increase in the proportion of cells entering into DNA synthesis. Down-regulation or selective inhibition of protein kinase C abolished this synergistic stimulation of DNA synthesis. Thapsigargin and DBHQ did not potentiate protein kinase C-mediated signals such as direct phosphorylation of myristoylated alanine-rich C-kinase substrate, activation of mitogen-activated protein kinase, and tyrosine phosphorylation of bands 110,000-130,000 and 70,000-80,000. Thapsigargin and DBHQ caused a marked reduction in the ability of bombesin to induce a rapid and transient increase in intracellular Ca2+ via depletion of total cellular Ca2+, measured by 45Ca2+ content. The synergistic stimulation of DNA synthesis by DBHQ and phorbol 12,13-dibutyrate was dependent on a high concentration of extracellular Ca2+ (ED50 = 410 microM) and was preferentially inhibited by the inhibitor of Ca2+ influx econozole. This suggests a role for Ca2+ entry in growth control. This is the first time that either thapsigargin or DBHQ has been shown to stimulate the reinitiation of DNA synthesis in any target cell.
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PMID:Thapsigargin and di-tert-butylhydroquinone induce synergistic stimulation of DNA synthesis with phorbol ester and bombesin in Swiss 3T3 cells. 779 54

The effects of pharmacological agents that interfere with the 1,4,5-inositol trisphosphate (IP3)/diacylglycerol (DAG) pathway on juvenile hormone (JH) biosynthesis by corpora allata (CA) of the cockroach Diploptera punctata have been investigated. These effects were assessed in the presence of the inhibitory neuropeptides, allatostatins, with a view to elucidating the pathway for signal transduction in the inhibition of JH biosynthesis. Treatment of CA with inhibitors of DAG kinase to elevate the concentration of DAG within the CA cells, resulted in a significant, dose-dependent decrease in JH biosynthesis. Simultaneous treatment of glands with both DAG kinase inhibitors and allatostatins further enhanced this effect, suggesting that DAG is an intermediate in the allatostatin-induced inhibition of JH production. The inhibitory actions of the phorbol ester activator of PKC, PDBu, or of allatostatin on JH biosynthesis were partially blocked by pre-incubating the CA with PKC inhibitors. Treatment of CA with the calcium-mobilizing drug thapsigargin resulted in a significant stimulation in JH biosynthesis in glands from mated females producing JH at high rates. Thapsigargin was also able to reverse the effect of allatostatins in high-activity mated CA. This suggests an involvement of the other product of phosphoinositide hydrolysis, IP3, in the modulation of JH biosynthesis at specific developmental times and in glands showing specific levels of activity.
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PMID:Signal transduction in the inhibition of juvenile hormone biosynthesis by allatostatins: roles of diacylglycerol and calcium. 782 22

Peptide hormones control salt reabsorption in cortical thick ascending limb (cTAL) cells of the loop of Henle. These agonists act, in part, through alterations on intracellular Ca2+ ([Ca2+]i). Primary cell cultures were prepared from porcine kidneys using a double antibody technique (goat antihuman Tamm-Horsfall and rabbit antigoat IgG antibodies). [Ca2+]i was determined in single cells with fluorescent techniques using fura-2. Parathyroid hormone (PTH) and arginine vasopressin (AVP) transiently increased [Ca2+]i in a dose-dependent manner. [Ca2+]i maximally increased from 85 +/- 5 nmol/l to 608 +/- 99 nmol/l with PTH, 10(-6) M, and to 766 +/- 162 nmol/l with AVP, 10(-7) M. The increment in [Ca2+]i by both hormones was by intracellular Ca2+ release and entry through plasma membrane Ca2+ channels. 8-Bromo-adenosine-3',5'-cyclic monophosphate (8-BrcAMP), 10(-4) M, increased [Ca2+]i (basal 83 +/- 3 to 427 +/- 121 nmol/l) but only from internal sources as nifedipine (10 mumol), ([Ca2+]i changes: 86 +/- 4 to 390 +/- 29 nmol/l) and removal of bath Ca/+o, ([Ca2+]i changes: 84 +/- 6 to 517 +/- 142 nmol/l), were without effect on agonist-induced [Ca2+]i. Thapsigargin, 1.5 mumol, completely abolished the AVP- and cyclic adenosine monophosphate-(cAMP)-induced Ca2+ transients, and partially inhibited PTH-mediated Ca2+ transients by about 50%. Pretreatment with 8-BrcAMP inhibited the PTH and AVP responses likely through depletion of cAMP-sensitive Ca2+ stores. Activation of protein kinase C (PKC) with phorbol esters inhibited PTH and AVP responses and 8-BrcAMP-induced [Ca2+]i transients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hormone-mediated Ca2+ transients in isolated renal cortical thick ascending limb cells. 805 57


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