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

Many of the new tool drugs useful for the study of molecular mechanisms of ischemic preconditioning (IP) are very valuable in in vitro systems but produce undesired side-effects after systemic injection in intact animals that limit their applicability. Our aim was to develop an experimental in vivo model that allows the use of said drugs in sufficiently high local concentrations, but avoiding at the same time the systemic side-effects. Several techniques were combined to study regional damage or protection as a result of local drug infusion such as nuclear staining, NADH fluorescence, fluorescent microspheres and tetrazolium salts. In open-chest pigs, the intramyocardial infusion (20 microliters/min) of the adenosine A1-receptor agonist N6-cyclohexyladenosine (0.3 mmol) for 10 min prior to a 60-min LAD-occlusion and 120-min reperfusion mimicked IP by exerting a local protection (n = 9, p < 0.001). Krebs-Henseleit buffer (negative control) was without protective effect. IP's cardioprotection was locally prevented by the intramyocardial application of the adenosine A1-receptor antagonist cyclopentyltheophylline (1 mmol, infused during IP; n = 6, p < 0.001) but not by KHB. The protein kinase C (PKC)-inhibitors staurosporine (100 nmol, n = 6) or bisindolylmaleimide (BIS, 25 mumol, n = 9) did not prevent IP locally. The PKC activator phorbol myristate acetate (PMA, 1 mumol, n = 6) was ineffective in preventing ischemic injury and increased the amount of necrosis in IP, whereas BIS exerted a local myocardial protection (n = 9, p < 0.001). In conclusion, the new model of intramyocardial infusion appears to be useful for the investigation of IP's signal transduction. Our data support the role of the adenosine A1-receptor in IP, but suggest that inhibition instead of activation of PKC may protect ischemic myocardium from infarction.
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PMID:Intramyocardial infusion of tool drugs for the study of molecular mechanisms in ischemic preconditioning. 892 57

1. Whole-cell and amphotericin-perforated patch-clamp techniques have been used to study the effects of hydrogen peroxide (H2O2) on action potentials and underlying ionic currents in single myocytes from the ventricles of adult rat hearts. 2. The results obtained differed markedly depending on the recording method utilized. Conventional whole-cell recordings, in which the myoplasm is dialysed with the contents of the pipette, failed to show any significant effects of H2O2 on the action potential or cell shortening. In contrast, when action potentials were recorded with the amphotericin-perforated patch method, H2O2 (50-200 microM) produced a marked prolongation of the action potential and an increase in cell shortening. 3. Voltage-clamp recordings with the amphotericin-perforated patch method showed that H2O2 caused no significant changes in either the Ca(2+)-independent transient outward K+ current (Ito) or the inwardly rectifying K+ current (IK1). 4. Application of tetrodotoxin (TTX; 8 x 10(-6) M), a Na+ channel blocker, largely inhibited the effects of H2O2 on the action potential. Moreover, anthopleurin A (4 x 10 (-7) M), which augments Na+ current (INa) by slowing its inactivation, mimicked the effects of H2O2 on the action potential of ventricular myocytes. These effects on INa were also blocked almost completely by TTX. 5. The hypothesis that H2O2 can augment INa by slowing its kinetics of inactivation was tested directly using ensemble recordings from cell-attached macropatches. These results demonstrated a significant enhancement of late opening events when H2O2 (200 microM) was included in the recording pipette. A corresponding slowing of inactivation of the ensemble INa was observed. 6. The possibility that protein kinase C (PKC) is an intracellular second messenger for the observed effects of H2O2 was examined using the blocker bisindolylmaelimide (BIS; 10(-7) M). Bath application of BIS prior to H2O2 exposure significantly delayed and also attenuated the development of the action potential prolongation. 7. These results demonstrate marked electrophysiological effects of H2O2 in rat ventricle. The dependence of these effects on recording methods suggests involvement of an intracellular second messenger, and the results with the PKC inhibitor, BIS, support this possibility. The most prominent effect of H2O2 on the ionic currents which underlie the action potential is a slowing of inactivation of the TTX-sensitive INa. Recent molecular studies have demonstrated a PKC phosphorylation site on the rat cardiac Na+ channel isoform and have also shown that PKC activation can slow inactivation of INa.
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PMID:Ionic mechanism of the effects of hydrogen peroxide in rat ventricular myocytes. 916 81

Accumulating evidence indicates that prostaglandins play an important role in the pathogenesis of periodontal disease. In this study, the effects and interactions between IL-1beta and TNFalpha on prostaglandin production and its regulation were investigated. The cytokines IL-1beta and TNFalpha stimulated prostaglandin E2 (PGE2) and prostacyclin (PGI2) production in gingival fibroblasts. Simultaneous treatment of the cells with IL-1beta and TNFalpha resulted in a synergistic stimulation of PGE2 and PGI2 formation. IL-1beta and, to a lesser extent, TNFalpha stimulated the release of 3H-arachidonic acid (3H-AA), and simultaneous addition of IL-1beta and TNFalpha further increased the release of 3H-AA from pre-labeled gingival fibroblasts. Furthermore, IL-1beta and, to a lesser extent, TNFalpha induced the expression of cyclooxygenase-2 (COX-2) mRNA. Simultaneous addition of IL-1beta and TNFalpha synergistically enhanced COX-2 mRNA levels, accompanied by a corresponding stimulation of PGE2 synthesis. Neither IL-1beta, TNFalpha, nor the combination of these two cytokines affected COX-1 mRNA levels. PMA, known to activate protein kinase C (PKC), enhanced the stimulatory effect of IL-1beta, TNFalpha, and the combination on COX-2 mRNA levels accompanied by a corresponding increase in PGE2 production. The phospholipase A2 (PLA2) inhibitor, BPB, and the PKC inhibitor, BIS, reduced PGE2 production, whereas dexamethasone, indomethacin, and NS-398 completely abolished PGE2 production induced by IL-1beta, TNFalpha, and the combination. The study indicates that the synergistic stimulation of prostaglandin production by IL-1beta, and TNFalpha is mediated partly at the level of COX-2 and partly at the level of PLA2 and that PKC is involved in the signal transduction of the synergy between the two cytokines. The synergy between IL-1beta and TNFalpha may play an important role in the inflammatory processes in gingival tissue in vivo.
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PMID:Signal transduction pathways involved in the synergistic stimulation of prostaglandin production by interleukin-1beta and tumor necrosis factor alpha in human gingival fibroblasts. 1006 47

1. The regulation of large conductance calcium- and voltage-activated potassium (BK) currents by activation of the protein kinase C (PKC) and glucocorticoid signalling pathways was investigated in AtT20 D16:16 clonal mouse anterior pituitary corticotroph cells. 2. Maximal activation of PKC using the phorbol esters, 4beta-phorbol 12-myristate, 13-acetate (PMA), phorbol 12, 13 dibutyrate (PDBu) and 12-deoxyphorbol 13-phenylacetate (dPPA) elicited a rapid, and sustained, inhibition of the outward steady-state voltage- and calcium- dependent potassium current predominantly carried through BK channels. 3. The effect of PMA was blocked by the PKC inhibitors bisindolylmaleimide I (BIS; 100 nM) and chelerythrine chloride (CHE; 25 microM) and was not mimicked by the inactive phorbol ester analogue 4alpha-PMA. 4. PMA had no significant effect on the 1 mM tetraethylammonium (TEA)-insensitive outward current or pharmacologically isolated, high voltage-activated calcium current. 5. PMA had no significant effect on steady-state outward current in cells pre-treated for 2 h with 1 microM of the glucocorticoid agonist dexamethasone. Dexamethasone had no significant effect on steady-state outward current amplitude or sensitivity to 1 mM TEA and did not block PMA-induced translocation of the phorbol ester-sensitive PKC isoforms, PKCalpha and PKCepsilon, to membrane fractions. 6. Taken together these data suggest that in AtT20 D16:16 corticotroph cells BK channels are important targets for PKC action and that glucocorticoids inhibit PKC signalling downstream of PKC activation.
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PMID:Glucocorticoid block of protein kinase C signalling in mouse pituitary corticotroph AtT20 D16:16 cells. 1020 Apr 23

To investigate the mechanisms by which phorbol esters potentiate transmitter release from mossy fibre terminals we used fura dextran to measure the intraterminal Ca2+ concentration in mouse hippocampal slices. A phorbol ester, phorbol 12,13-diacetate (PDAc), potentiated the field excitatory postsynaptic potential (fEPSP) slope. PDAc also enhanced the stimulation-dependent increase of [Ca2+]i in the mossy fibre terminal (Delta[Ca2+]pre). The magnitude of the PDAc-induced fEPSP potentiation (463+/-57% at 10 microM) was larger than that expected from the enhancement of Delta[Ca2+]pre (153+/-5%). The Delta[Ca2+]pre was suppressed by omega-agatoxin IVA (omega-AgTxIVA, 200 nM), a P/Q-type Ca2+ channel-specific blocker, by 31%. The effect of PDAc did not select between omega-AgTxIVA-sensitive and -resistant components. The PDAc-induced potentiation of the fEPSP slope was partially antagonized by the protein kinase C (PKC) inhibitor bisindolylmaleimide I (BIS-I, 10 microM), whereas the Delta[Ca2+]pre was completely blocked by BIS-I. Although the BIS-I-sensitive fEPSP potentiation was accompanied by a reduction of the paired-pulse ratio (PPR), the BIS-I-resistant component was not. Whole-cell patch clamp recording from a CA3 pyramidal neuron in a BIS-I-treated slice demonstrated that PDAc (10 microM) increased the frequency of miniature excitatory postsynaptic currents (mEPSCs, 259+/-33% of control) without a noticeable change in their amplitude (102+/-5% of control). These results suggest that PKC potentiates transmitter release by at least two distinct mechanisms, one Delta[Ca2+]pre dependent and the other Delta[Ca2+]pre independent. In addition, some phorbol ester-mediated potentiation of synaptic transmission appears to occur without activating PKC.
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PMID:Re-evaluation of phorbol ester-induced potentiation of transmitter release from mossy fibre terminals of the mouse hippocampus. 1111 4

Corticotropin-releasing factor (CRF) exerts a key neuroregulatory control on stress responses in various regions of the mammalian brain, including the hippocampus. Using hippocampal slices, extracts, and whole animals, we investigated the effects of human/rat CRF (h/rCRF) on hippocampal neuronal excitability and hippocampus-dependent learning in two mouse inbred strains, BALB/c and C57BL/6N. Intracellular recordings from slices revealed that application of h/rCRF increased the neuronal activity in both mouse inbred strains. Inhibition of protein kinase C (PKC) by bisindolylmaleimide I (BIS-I) prevented the h/rCRF effect only in hippocampal slices from BALB/c mice but not in slices from C57BL/6N mice. Inhibition of cAMP-dependent protein kinase (PKA) by H-89 abolished the h/rCRF effect in slices from C57BL/6N mice, with no effect in slices from BALB/c mice. Accordingly, h/rCRF elevated PKA activity in hippocampal slices from C57BL/6N mice but increased only PKC activity in the hippocampus of BALB/c mice. These differences in h/rCRF signal transduction were also observed in hippocampal membrane suspensions from both mouse strains. In BALB/c mice, hippocampal CRF receptors coupled to G(q/11) during stimulation by h/rCRF, whereas they coupled to G(s), G(q/11), and G(i) in C57BL/6N mice. As expected on the basis of the slice experiments, h/rCRF improved context-dependent fear conditioning of BALB/c mice in behavioral experiments, and BIS-I prevented this effect. However, although h/rCRF increased neuronal spiking in slices from C57BL/6N mice, it did not enhance conditioned fear. These results indicate that the CRF system activates different intracellular signaling pathways in mouse hippocampus and may have distinct effects on associative learning depending on the mouse strain investigated.
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PMID:Corticotropin-releasing factor receptors couple to multiple G-proteins to activate diverse intracellular signaling pathways in mouse hippocampus: role in neuronal excitability and associative learning. 1253 30

The proinflammatory mediator bradykinin (BK) is suggested to play an important role in the pathogenesis of various inflammatory diseases including periodontitis. In this study, BK per se stimulated interleukin-8 (IL-8) production in human gingival fibroblasts in vitro. Furthermore, BK upregulated the stimulatory effect of the cytokines IL-1beta and TNFalpha on the production of IL-8. The stimulatory effect of BK on the IL-1beta- or TNFalpha-stimulated IL-8 production was reduced in the presence of BK B2 receptor antagonist HOE 140, whereas the B1 receptor antagonist Lys-(des-arg9, Leu8)-BK had no effect. Similar to BK, the calcium ionophore A23187 also upregulated the stimulatory effect of IL-1beta and TNFalpha on IL-8 production. The protein kinase C (PKC) inhibitor bisindolylmaleimide, BIS, significantly reduced the stimulatory effect of BK on IL-1beta and TNFalpha increased IL-8 production but did not affect the production of IL-8 stimulated by cytokines alone. The specific p38 mitogen-activated protein kinase (MAPK) inhibitor SB 203580 reduced IL-8 production stimulated by the combination of BK and IL-1beta as well as the IL-1beta-stimulated IL-8 production. In conclusion, this study shows that BK upregulates IL-1beta- and TNFalpha-stimulated IL-8 production via BK B2 receptor and that PKC signal pathway seems to be involved in the upregulation of the cytokine-induced IL-8 production in gingival fibroblasts. This stimulatory effect of BK on IL-8 production may contribute to the maintenance of the gingival inflammation and enhanced risk for destruction of gingival connective tissue.
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PMID:Bradykinin upregulates IL-8 production in human gingival fibroblasts stimulated by interleukin-1beta and tumor necrosis factor alpha. 1566 65

Hypocretins are crucial for the regulation of wakefulness by the excitatory actions on multiple subcortical arousal systems. To date, there is little information about the direct postsynaptic excitatory effects of hypocretins on the neurons in prefrontal cortex (PFC), which is important for higher cognitive functions and is correlated with level of wakefulness. In this study, we tested the excitatory effects of hypocretin-1 on acutely isolated PFC pyramidal neurons of rats and studied the possible ionic mechanisms by using whole-cell patch-clamp techniques. Puff application of hypocretin-1 caused a dose-dependent excitation. Further observations that perfusion of Ca2+-free artificial cerebrospinal fluid did not influence the depolarizing effects of hypocretin-1, in conjunction with the findings that hypocretin-1 could decrease net whole-cell K+ currents, demonstrate that the excitatory effects of hypocretin-1 on PFC neurons are mediated by the inhibition of K+ currents but not Ca2+ influx. Finally, the decrease in K+ currents induced by hypocretin-1 was abolished by a protein kinase C (PKC) inhibitor (BIS II) or a phospholipase C (PLC) inhibitor (D609), suggesting that PKC and PLC appear to be involved in mediating the inhibitory effects of hypocretin-1 on K+ currents. These results indicate that hypocretin-1 exerts a postsynaptic excitatory action on PFC neurons through the inhibition of K+ currents, which probably results from activation of PKC and PLC signaling pathways.
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PMID:Postsynaptic excitation of prefrontal cortical pyramidal neurons by hypocretin-1/orexin A through the inhibition of potassium currents. 1624 2

In the absence of progesterone (P), the anti-P at the receptor RU486 reduces basal and GnRH-stimulated LH secretion both in vivo and in vitro, demonstrating the existence of a ligand-independent activation of progesterone receptor (LIAPR). The aim of the present study was to determine which component of the intracellular LH secretory pathway activated by GnRH is responsible for LIAPR. To do this, anterior pituitary dispersed cells from female rats in proestrus, cultured in the presence of 17beta-estradiol, were incubated with activators or inhibitors of PKC, cAMP-PKA signalling pathways or intracellular calcium (Ca2+) traffic, in the presence or absence of RU486. Results showed that RU486 reduced both GnRH- and the PKC activator PMA-induced LH secretion. In GnRH-stimulated cells incubated with the PKC inhibitor BIS-I or treated with PMA "overnight", RU486 had no effect on reduced LH secretion, nor on stimulated LH secretion elicited by the Ca2+ ionophore ionomycin. Moreover, when GnRH- or PMA-treated cells were co-incubated with 1 microM of the L-type Ca2+ channel blocker nifedipine or the intracellular Ca2+ chelator BAPTA-AM, RU486 potentiated the expected inhibition of these drugs on LH secretion. Activation (forskolin, 8-Br-cAMP) or inhibition (MDL-12,330A) of the cAMP-PKA signalling cascade affected neither the GnRH- and PMA-induced increase of LH secretion nor the reduction of LH secretion due to RU486. Taken together, the data point to the existence of a Ca2+ -independent PKC-PR cross-talk mechanism as part of the intracellular signalling of GnRH-stimulated LH secretion.
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PMID:Protein kinase C cross-talk with gonadotrope progesterone receptor is involved in GnRH-induced LH secretion. 1690 30

Nerve growth factor (NGF) can regulate nitric oxide synthase (NOS) expression and nitric oxide (NO) can modulate NGF-mediated neurotrophic responses. In this study, the role of NO in NGF-stimulated amyloid precursor protein (APP) levels was studied. PC12 cells were treated with either the non-selective NOS inhibitor N(omega)-nitro-L-arginine methylester (L-NAME) or the inducible NOS selective inhibitor s-methylisothiourea (S-MIU), and the effect on NGF-mediated increases in APP expression was determined. NGF significantly increased total APP protein levels following 96 h of treatment and this increase was prevented in cells pre-treated with S-MIU. Pre-treatment of cells with actinomycin D also blocked this NGF-mediated induction of APP, indicating de novo protein synthesis is necessary. Treatment with NGF increased APP promoter activity; however, this increase was only partially inhibited by pre-treatment with S-MIU and was increased in the presence of L-NAME. This suggests that NO may be modulating other aspects of APP expression in addition to transcription. Inhibition of NGF signaling pathways was also investigated using inhibitors of mitogen-activated protein (MAP) kinase (U0126), Akt (LY294002) and protein kinase C (PKC; U73122 and bisindolylmaleimide 1 (BIS-1)) activation. Inhibition of each of these pathways prevented NGF-mediated increases in APP protein expression; however, only BIS-1 attenuated NGF-mediated increases in promoter activation. This study indicates that NO is involved in the NGF-mediated regulation of APP, in part at the level of APP transcription and could involve the modulation of NGF signal transduction pathways.
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PMID:Nitric oxide synthase inhibitors modulate nerve growth factor-mediated regulation of amyloid precursor protein expression in PC12 cells. 1740 71


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