EC:2.7.11.13 - FACTA Search

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)

Glutamate-induced neurotoxicity was examined in cultured rat cortical cells. Primary cultures were obtained from the cerebral cortex of fetal rats (17-19 days of gestation). Single cells dissociated from the cerebral cortex were plated on plastic coverslips placed in 35- or 60-mm culture dishes. Cultures were incubated in Eagle's minimal essential medium supplemented with 10% fetal calf serum or 10% horse serum at 37 degrees C in a humidified 5% CO2 atmosphere for 10-14 days. The neurotoxicity induced by glutamate was quantified by trypan blue exclusion. The viability of cultures was markedly reduced by a 10-min exposure to glutamate followed by incubation with glutamate-free medium for 1-24 hr. Glutamate neurotoxicity was prevented by the N-methyl-D-aspartate (NMDA) receptor antagonists, MK-801, 3-[(+/-)-2-carboxypiperazin-4-yl] propyl-1-phosphoric acid (CPP), ifenprodil and 7-Cl-kinurenate. Glutamate neurotoxicity was augmented by phorbol dibutyrate, that activates protein kinase C (PKC), but reduced by H-7, that inhibits PKC. These results suggest that PKC plays an important role in NMDA receptor-mediated glutamate neurotoxicity in the cerebral cortex.
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PMID:[Experimental techniques for developing new drugs acting on dementia (11)--Experimental methods on glutamate neurotoxicity]. 890 96

The signal transduction pathway of hypoxic pulmonary arterial contraction has not been elucidated. Phosphorylation of the 20-kDa myosin light chain (MLC20) is thought to be essential for vascular muscle contraction. However, there are reports that smooth muscle will contract in response to nonphysiological stimuli such as phorbol esters without the involvement of MLC20 phosphorylation. The purpose of this study was to determine if hypoxia-induced pulmonary arterial contraction is dependent on MLC20 phosphorylation. Isolated rat pulmonary and carotid (for comparative purposes) arterial strips were contracted with 80 mM KCl to establish maximum active tension in response to membrane depolarization. The strips were then stimulated with one of the following: 30 mM KCl, 1 microM phenylephrine, 0.01 microM angiotensin II, 1 microM phorbol 12-myristate 13-acetate (PMA), or hypoxia (95% N2-5% CO2). In some experiments ML-9, a myosin light chain kinase inhibitor, or calphostin C, a protein kinase C (PKC) inhibitor, was introduced into the bath before hypoxia. Isometric tension was recorded as a function of time. Muscle strips were freeze-clamped (liquid N2) at various time points during the course of responses to the various stimuli. MLC20 phosphorylation levels were measured by ureaglycerol gel electrophoresis followed by Western blot procedure. Results show that increased MLC20 phosphorylation correlates with initiation of pulmonary arterial smooth muscle contraction in response to all agonists with the exception of PMA, a known activator of PKC. The MLC20 phosphorylation levels correlate with tension development in response to hypoxia, and ML-9 abolished the hypoxic contractions. In contrast, hypoxia relaxed carotid arterial muscle, and there was a corresponding decrease in the MLC20 phosphorylation level. In conclusion, hypoxia appears to result in MLC20 phosphorylation-mediated contraction in conduit pulmonary arterial muscle and in MLC20 dephosphorylation-mediated relaxation in systemic arterial muscle.
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PMID:Hypoxia-induced pulmonary arterial contraction appears to be dependent on myosin light chain phosphorylation. 894 20

Roles of Ca2+ and protein kinase C (PKC) in the regulation of acid/base transport in isolated rabbit proximal tubules were investigated by measuring cytosolic Ca2+ concentrations ([Ca2+]i) and cell pH (pHi) with fluorescent probes. Ionomycin (0.2 microM) increased [Ca2+]i by approximately 200 nM but did not affect the basolateral Na(+)-HCO3- cotransporter. However, the apical Na+/H+ exchanger was inhibited by 50% by ionomycin, and this inhibition was abolished either by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, an intracellular Ca2+ chelator, or by KN-62, an inhibitor of calcium-calmodulin-dependent protein kinase II (CaM kinase II). On the other hand, phorbol 12-myristate 13-acetate (PMA, 0.5 microM) did not affect the apical Na+/H+ exchanger but did stimulate the basolateral Na(+)-HCO3- cotransporter by 60-80%, and this stimulation was prevented by calphostin C, an inhibitor of PKC. Consistent with the cotransporter stimulation, PMA decreased steady-state pHi in the presence of CO2/ HCO3-. These results indicate that 1) the acute increase in [Ca2+]i within physiological ranges inhibits the apical Na+/H+ exchanger, probably through mediation of CaM kinase II; and 2) the short-term PKC activation stimulates the basolateral Na(+)-HCO3- cotransporter.
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PMID:Roles of Ca2+ and PKC in regulation of acid/base transport in isolated proximal tubules. 894 2

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

The present study was designed in order to investigate more precisely the role of calcium homeostasis maintenance in protein kinase C (PKC) mediated preconditioning. We used a 15 min pre-incubation period, with 1 mumol/l exogenous norepinephrine (NE) to pharmacologically precondition isolated, superfused rat trabeculae against contractile dysfunctioning following 120 min of metabolic inhibition (MI, in 2 mmol/l CN- containing Tyrode without glucose at 1 Hz stimulation frequency). Contractile recovery was studied during a subsequent 60 min recovery period (RP, in glucose containing Tyrode at 0.2 Hz). Tyrode was gassed with 95%, O2/ 5% CO2 and kept at a constant temperature of 24 degrees C. Force and intracellular free calcium ([Ca2+]i) were monitored throughout the experimental protocol; [Ca2+]i was measured using fura-2. Pretreatment with NE (group NE-I) significantly increased the fraction of trabeculae that resumed to contract during RP, from 36 +/- 13% (mean +/- S.E.M.) in controls to 82 +/- 10% (P < 0.05). In correspondence with this, NE-pretreatment increased the proportion of trabeculae in which the Ca2+ rise from the onset of rigor development during MI was attenuated. After 40 min of MI [Ca2+]i in the failing control, as well as failing group NE-I, trabeculae (1.08 +/- 0.20 and 1.51 +/- 0.26 mumol/l, respectively) was increased significantly compared to the mean value registered in the recovering preparations of these groups (0.34 +/- 0.04 mumol/l: P < 0.05). Specific inhibition of PKC with 2 mumol/l chelerythrine (group NE-IV) almost completely blocked the protection induced by NE-pretreatment, including its protective action against Ca2+ overload, i.e. the fraction of trabeculae that resumed to contract during RP returned to untreated control level (46 +/- 11%: P < 0.05 v group NE-I). Also in this case [Ca2+]i in the failing group NE-IV trabeculae after 40 min of MI was increased substantially, compared to the value measured in the recovering preparations (4.75 +/- 1.00 and 0.60 +/- 0.08 mumol/ l, respectively). The relative importance of both alpha-adrenergic and beta-adrenergic receptor pathways in this preconditioning-like effect of NE-pretreatment, was investigated using specific blockers. The results point to an alpha 1-adrenergic receptor mediated signaling mechanism, which enhances PKC-dependent control of [Ca2+]i from the onset of rigor development during MI.
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PMID:Norepinephrine pretreatment attenuates Ca2+ overloading in rat trabeculae during subsequent metabolic inhibition: improved contractile recovery via an alpha 1-adrenergic, PKC-dependent signaling mechanism. 920 20

Although protein kinase C (PKC) is an essential component of multiple neurally mediated events, its role in respiratory control remains undefined. The ventilatory effects of a systemically active PKC inhibitor (Ro-32-0432; 100 mg/kg i.p.) were assessed by whole body plethysmography during normoxia, hypoxia (10% O2), and hyperoxia (100% O2) in unrestrained Sprague-Dawley rats. A sustained expiratory time increase occurred within 8-10 min of injection in room air[mean 44.8 +/- 5.2 (SE) % ], was similar to expiratory time prolongations after Ro-32-0432 administration during 100% O2 (45.5 +/- 8.1%; not significant), and was associated with mild minute ventilation (VE) decreases. Hypercapnic ventilatory responses (5% CO2) remained unchanged after Ro-32-0432. During 10% O2, VE increased from 122.6 +/- 15.6 to 195.7 +/- 10.1 ml/min in vehicle-treated rats (P < 0.001). In contrast, marked attenuation of VE hypoxic responses occurred after Ro-32-0432 [86.2 +/- 6.2 ml/min in room air to 104.1 +/- 7.1 ml/min in 10% O2; pre- vs. post-Ro32-0432, P < 0.001 (analysis of variance)]. Overall, PKC activity was reduced and increases with hypoxia were abolished in the particulate subcellular fraction of brain tissue after Ro-32-0432 treatment, indicating that this compound readily crosses the blood-brain barrier. We conclude that systemic PKC inhibition elicits significant centrally mediated expiratory prolongations and ventilatory reductions as well as blunted ventilatory responses to hypoxia but not to hypercapnia. We postulate that PKC plays an important role in signal transduction pathways within brain regions underlying respiratory control.
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PMID:Cardiorespiratory responses to systemic administration of a protein kinase C inhibitor in conscious rats. 947 76

The effect of angiotensin II (Ang II) on the activity of the cardiac Na+-independent Cl--HCO3- exchanger (anionic exchanger [AE]) was explored in cat papillary muscles. pHi was measured by epifluorescence with BCECF-AM. Ang II (500 nmol/L) induced a 5-(N-ethyl-N-isopropyl)amiloride-sensitive increase in pHi in the absence of external HCO3- (HEPES buffer), consistent with its stimulatory action on Na+-H+ exchange (NHE). This alkalinizing effect was not detected in the presence of a CO2-HCO3- buffer (pHi 7.07+/-0.02 and 7.08+/-0.02 before and after Ang II, respectively; n=17). Moreover, in Na+-free HCO3--buffered medium, in which neither NHE nor Na+-HCO3- cotransport are acting, Ang II decreased pHi, and this effect was canceled by previous treatment with SITS. These findings suggested that the Ang II-induced activation of NHE was masked, in the presence of the physiological buffer, by a HCO3--dependent acidifying mechanism, probably the AE. This hypothesis was confirmed on papillary muscles bathed with HCO3- buffer that were first exposed to 1 micromol/L S20787, a specific inhibitor of AE activity in cardiac tissue, and then to 500 nmol/L Ang II (n=4). Under this condition, Ang II increased pHi from 7.05+/-0.05 to 7.22+/-0.05 (P<.05). The effect of Ang II on AE activity was further explored by measuring the velocity of myocardial pHi recovery after the imposition of an intracellular alkali load in a HCO3--containing solution either with or without Ang II. The rate of myocardial pHi recovery was doubled in the presence of Ang II, suggesting a stimulatory effect on AE. The enhancement of the activity of this exchanger by Ang II was also detected when the AE activity was reversed by the removal of extracellular Cl- in a Na+-free solution. Under this condition, the rate of intracellular alkalinization increased from 0.053+/-0.016 to 0.108+/-0.026 pH unit/min (n=6, P<.05) in the presence of Ang II. This effect was canceled either by the presence of the AT1 receptor antagonist, losartan, or by the previous inhibition of protein kinase C with chelerythrine or calphostin C. The above results allow us to conclude that Ang II, in addition to its stimulatory effect on alkaline loading mechanisms, activates the AE in ventricular myocardium and that the latter effect is mediated by a protein kinase C-dependent regulatory pathway linked to the AT1 receptors.
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PMID:Angiotensin II activates Na+-independent Cl--HCO3- exchange in ventricular myocardium. 950 8

Intracellular pH is under strict control in myocardium; H+ are extruded from the cells by sodium-dependent mechanisms, mainly Na+/H+ exchanger and Na+/HCO3- symport, whereas Na+-independent Cl-/HCO3- exchanger extrudes bases on intracellular alkalinization. Hypertrophic myocardium from spontaneously hypertensive rats (SHR) exhibits increased Na+/H+ exchange activity that is accompanied by enhanced extrusion of bases through Na+-independent Cl-/HCO3- exchange. The present experiments were designed to investigate the effect of enalapril-induced regression of cardiac hypertrophy on the activity of these exchangers. Male SHR and normotensive Wistar-Kyoto rats (WKY) received enalapril maleate (20 mg/kg per day) in the drinking water for 5 weeks. Gender- and age-matched SHR and WKY were used as untreated controls. Enalapril treatment significantly reduced systolic blood pressure in SHR and completely regressed cardiac hypertrophy. Na+/H+ activity was estimated in terms of both steady pHi value in HEPES buffer and the rate of pHi recovery from CO2-induced acid load. Na+-independent Cl-/HCO3- activity was assessed by measuring the rate of pHi recovery from intracellular alkalinization produced by trimethylamine exposure. Regression of cardiac hypertrophy was accompanied by normalization of Na+/H+ and Na+-independent Cl-/HCO3- exchange activities. Inhibition of protein kinase C (PKC) activity with chelerythrine (10 mmol/L) or calphostin C (50 nmol/L) returned both exchange activities to normal values. These results show that angiotensin-converting enzyme inhibition normalizes the enhanced activity of both exchangers while regressing cardiac hypertrophy. Because normalization of exchange activities could be also achieved by PKC inhibition, the data would suggest that PKC-dependent mechanisms play a significant role in the increased ion exchange activities of hypertrophic myocardium and in their normalization by angiotensin-converting enzyme inhibition.
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PMID:Enalapril induces regression of cardiac hypertrophy and normalization of pHi regulatory mechanisms. 953 21

We examined the effect of respiratory acidosis on the Na-HCO3 cotransporter activity in primary cultures of the proximal tubule of the rabbit exposed to 10% CO2 for 5 min, 2, 4, 24 and 48 hr. Cells exposed to 10% CO2 showed a significant increase in Na-HCO3 cotransporter activity (expressed as % of control levels, 5 min: 142 +/- 6, 2 hr: 144 +/- 13, 4 hr: 145 +/- 11, 24 hr: 150 +/- 15, 48 hr: 162 +/- 24). The increase in activity was reversible after 48 hr. The role of protein kinase C (PKC) on the stimulatory effect of respiratory acidosis on the cotransporter was examined in presence of PKC inhibitor calphostin C or in presence of PKC depletion. Both calphostin C and PKC depletion prevented the effect of 10% CO2 for 5 min or 4 hr to increase the activity of the cotransporter. 10% CO2 for 5 min or 4 hr increased total and particulate fraction PKC activity. To examine the role of phosphotyrosine kinase (PTK) on the increase in cotransporter activity we studied the effect of two different inhibitors, 2-hydroxy-5-(2,5-dihydroxylbenzyl) aminobenzoic acid (HAC) and methyl 2,5-dihydroxycinnamate (DHC) which inhibit phosphotyrosine kinase in basolateral membranes. Cells were pretreated either with vehicle or HAC or DHC and then exposed to 10% CO2 for 5 min or 4 hr. In cells treated with vehicle, 10% CO2 significantly increased cotransporter activity as compared to control cells exposed to 5% CO2. This stimulation by 10% CO2 was completely prevented by HAC or DHC at 5 min (5% CO2: 1.8 +/- 0.2, 10% CO2: 2.6 +/- 0.2, 10% CO2 + HAC: 1.6 +/- 0.2, 10% CO2: +DHC: 2.0 +/- 0.3 pH unit/min) and also at 4 hr. The protein synthesis inhibitors actinomycin D and cycloheximide appear to prevent the effect of 10% CO2 for 4 hr on the cotransporter. Our results show that early respiratory acidosis stimulates the Na-HCO3 cotransporter through PKC and PTK-dependent mechanisms and the late effect appears to be mediated through protein synthesis.
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PMID:Regulation of renal Na-HCO3 cotransporter: VIII. Mechanism Of stimulatory effect of respiratory acidosis. 954 92

Recently we have found that hypercapnia induces nuclear protein (FOS) expression in the brainstem chemosensitive neurons, including catecholamine-containing cells. In the present studies we examined the role of protein kinase C (PKC) pathway in CO2-induced c-fos expression. Because of the complexity of the CNS system, experiments were performed in pheochromocytoma cells (PC12 cells). These cells originate from neuronal crest and express catecholaminergic traits. We depleted PKC from PC12 cells by prolonged (48 h) exposure to high concentration of phorbol 12-myristate, 13-acetate (PMA, 100 nM), and then determined the expression of: (1) c-fos mRNA by Northern blot (2) PKC isoforms, tyrosine phosphorylated and unphosphorylated MAP (mitogen activated protein) kinases by Western blot. Depletion of PKC abolished the effect of CO2 on c-fos mRNA expression, inhibited MAP kinases tyrosine phosphorylation and suppressed the expression of PKC(alpha) and PKC(zeta). These results suggest that MAP kinases, PKC(alpha) and/or PKC(beta) might be involved in CO2-induced c-fos mRNA expression.
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PMID:A possible role for protein kinase C in CO2/H+-induced c-fos mRNA expression in PC12 cells. 957 65

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