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)

1 The present study has investigated the alpha1-adrenoceptor subtype mediating contraction of the rat isolated prostatic vas deferens and the possible effector mechanisms involved in this response by use of functional experiments. 2 Contractions to noradrenaline in the rat isolated prostatic vas deferens were antagonized by prazosin (9.4, 1.04+/-0.19, pA2 and Schild plot slope), 5-methyl urapidil (8.9, 1.10+/-0.13), BMY 7378 (6.4, 1.53+/-0.07) and RS 17053 (8.3, 1.13+/-0.18). These affinities are consistent with the response being mediated by the alpha1A-adrenoceptor subtype. 3 The contraction to noradrenaline at 37 degrees C consisted of an initial phasic response, composed of many rhythmic contractile spikes and a more slowly developing tonic contraction. When the temperature was lowered to 25 degrees C the phasic contraction became a smooth single response which was increased in magnitude. 4 In Ca2+-free Krebs solution the tonic contraction to noradrenaline (10(-4) M) was abolished, suggesting that this response was dependent on influx of extracellular Ca2+. After 2 min in Ca2+-free Krebs solution at 37 degrees C and 25 degrees C the phasic response to noradrenaline (10(-4) M) was 38+/-2% and 91+/-4%, respectively, compared with the phasic contraction to noradrenaline (10(-4) M in normal Krebs solution) and after 30 min it was abolished at 37 degrees C and was 7+/-1% at 25 degrees C. Ryanodine abolished the noradrenaline response in Ca2+-free Krebs solution for 2 min at 25 degrees C, while cyclopiazonic acid reduced it to 36+/-2%. 5 In normal Krebs solution at 25 degrees C the protein kinase C inhibitor calphostin C reduced the tonic contraction to noradrenaline (10(-5) M) from 36+/-8% to 14+/-3% compared with the phasic contraction to noradrenaline (10(-4) M). The DAG kinase inhibitor R 59022 increased the contraction following the initial phasic response to a maximum of 107+/-17% after 35 s, before dropping down to a well maintained contraction which was still greater in magnitude compared with the control. Nifedipine (3x10(-7) M) reduced the tonic contraction from 49+/-6% to 7+/-1% but did not reduce the phasic response. Ryanodine (10(-4) M) reduced the phasic contraction from 50+/-2% to 7+/-1% and the tonic response from 47+/-5% to 27+/-5%. 6 The phorbol ester phorbol-12,13-dibutyrate at 25 degrees C produced a transient contraction of the rat prostatic vas deferens, maximum response (10(-5) M) 48+/-4%, compared with the maximum tonic response to noradrenaline. The contraction to PDBu (10(-5) M) was reduced to 23+/-2% by calphostin C (10(-6) M) and to 15+/-1% by nifedipine (3x10(-7) M) and was abolished after 2 min in Ca2+-free Krebs solution. 7 In conclusion, the alpha1A-adrenoceptor mediated contraction to noradrenaline of the rat prostatic vas deferens appears to consist of an initial phasic component due to the release of intracellular Ca2+ from ryanodine-sensitive stores. These stores are depleted in the absence of extracellular Ca2+ and this depletion is slower at 25 degrees C than at 37 degrees C. The phasic contraction is followed by a tonic contraction involving activation of protein kinase C by diacylglycerol and influx of Ca2+ through nifedipine-sensitive channels.
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PMID:Alpha1A-adrenoceptor mediated contraction of rat prostatic vas deferens and the involvement of ryanodine stores and Ca2+ influx stimulated by diacylglycerol and PKC. 948 21

The second cysteine-rich (Cys-2) domain of rat brain PKC-gamma regulatory region C1 (92-173) was expressed in Escherichia coli cells and purified. NMR studies of Cys-2 protein identified the phorbol and other phospholipid binding sites within this molecule (Xu, R.X., Pawelczyk, T., Xia, T-H. and Brown, S.T. (1997) Biochemistry 37, 10709-10717). Here, we tested the ability of this domain to bind other proteins. Using an overlay assay we show that the Cys-2 domain binds other proteins in Xenopus oocyte soluble fraction. Unlike the kinase activity, binding of Cys-2 to other proteins was detected in the absence of added phospholipids. Microinjection of Cys-2 protein into Xenopus leavis oocytes inhibited insulin-induced but not progesterone-induced maturation. The smallest dose that enhanced insulin-induced maturation was 0.45 x 10(-12) mol injected Cys-2. These results demonstrate that the PKC-gamma Cys-2 domain beside being the binding site for phorbol ester/DAG and phosphatidylserine binds also other proteins. The proteins that interact with Cys-2 domain of PKC are essential for insulin-induced maturation program in oocytes.
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PMID:Recombinant protein kinase C-gamma phorbol binding domain upon microinjection blocked insulin-induced maturation of Xenopus laevis oocytes. 950 36

The protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) stimulates both the synthesis and phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PtdCho). Here, attached and suspended NIH 3T3 fibroblasts as well as variants of the MCF-7 human breast carcinoma cell line expressing PKC-alpha and a PtdCho-specific PLD activity at widely different levels were used to determine the possible role of PKC-alpha, PtdCho hydrolysis, and choline uptake in the mediation of PMA effect on PtdCho synthesis. In wild-type MCF-7 cells, which express both PKC-alpha and PLD activities at very low levels, PMA had little effects on the uptake or incorporation [14C]choline into PtdCho. In multidrug resistant MCF-7/MDR1 cells, which highly express PKC-alpha but lack the PtdCho-specific PLD activity, 100-nM PMA had relatively small stimulatory effects on the uptake of [14C]choline (approximately 1.5-fold) and [14C]PtdCho synthesis (1.5- to 2-fold). In NIH 3T3 fibroblasts and MCF-7/PKC-alpha cells, both expressing PKC-alpha and PLD activities at high levels, 10-100-nM PMA enhanced [14C]choline uptake only slightly (1.7- to 2.2-fold), while it had much greater (approximately 4-9-fold) stimulatory effects on PtdCho synthesis. PMA significantly enhanced the formation of phosphatidic acid (PtdOH) in MCF-7/PKC-alpha cells (2.8-fold increase), but not in MCF-7/MDR1 cells (1.4-fold increase), while in both cell lines it had only small (1.3-1.5-fold) stimulatory effects on 1,2-diacylglycerol (1, 2-DAG) formation. In suspended NIH 3T3 cells, 200-300-mM ethanol blocked the stimulatory effect of PMA on PtdOH formation without affecting PtdCho synthesis indicating that neither PtdOH nor 1,2-DAG derived from it is a mediator of PMA effect on PtdCho synthesis. In attached NIH 3T3 cells, dimethylbenz[a]anthracene enhanced phosphocholine formation and, thus, choline uptake without increasing PtdCho synthesis or modifying the effect of PMA. While the results indicate that the stimulatory effect of PMA on PtdCho synthesis requires the expression of both PKC-alpha and a PtdCho-specific PLD, they do not support a role for 1,2-DAG, PtdOH or choline in the mediation of PMA effect.
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PMID:Phorbol ester stimulation of phosphatidylcholine synthesis requires expression of both protein kinase C-alpha and phospholipase D. 959 49

Visual excitation in rhabdomeric photoreceptors is thought to be mediated by activation of a light-regulated phospholipase C (PLC) and the consequent hydrolysis of phosphatidylinositol bisphosphate. Whereas much attention has been devoted to inositol trisphosphate (IP3) production and intracellular Ca2+ release, little is known about the possible role of the DAG branch in the generation of the light response. We have tested the effect of chemically distinct surrogates of DAG on isolated Lima photoreceptors. Application of the phorbol ester PMA (0.5-10 microM) or the alkaloid (-)-indolactam (20-100 microM) from a holding potential of -50 mV elicited an inward current, several hundred picoamperes in amplitude, accompanied by a pronounced increase in membrane conductance. The stereoisomers 4alpha-PMA and (+)-indolactam were both inactive, arguing for the specificity of the effects. Elevation of cytosolic Ca2+ by intracellular dialysis accelerated this current, whereas chelerythrine antagonized it, suggesting the involvement of PKC. The reversal potential of the membrane current induced by PKC activators was approximately +10 mV; replacement of extracellular Na with impermeant N-methyl-D-glucamine decreased its amplitude and shifted the reversal potential in the negative direction. Stimulation by PMA and (-)-indolactam was accompanied by a pronounced depression of light responsiveness; conversely, steady illumination reduced the size of the current elicited by these PKC activators. Taken together, these results support the notion that the DAG branch of the PLC cascade, in addition to its suggested participation in visual adaptation, may play a role in the activation of the photoresponse or a component thereof, probably in synergy with IP3-mediated Ca2+ release.
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PMID:Membrane current induced by protein kinase C activators in rhabdomeric photoreceptors: implications for visual excitation. 965 Dec 8

The cell surface glycoprotein CD44 is proposed as a main participant in cell adhesion and migration. We studied the function, expression, and distribution of CD44 in the invasive and metastatic F3II murine carcinoma cell line during adhesion, spreading, migration, and invasion. A mAb anti-CD44 (KM 201) dramatically blocked F3II cell adhesion on both plastic and hyaluronic acid coatings, as well as spreading on uncoated plastic surfaces (P < 0.01). KM201 mAb significantly inhibited F3II cell migration and invasion in Transwell chambers. Immunocytochemistry of spreading cells revealed that CD44 distributed in bands on the cell surface, particularly in the tip of leading edges and in the perinuclear zones of the cell membrane. CD44 antigen was never detected in filopodia or lamellipodia nor in focal adhesion-like structures, but was also detectable as strong interlamellar bands. Fully spread cells showed a decreased CD44 signal compared to cells in early stages of spreading. This decrease correlated with a reduced expression of CD44 as detected by Western blot. We also investigated the signals that may regulate CD44 expression in F3II cells. Treatment of F3II cells, with phorbol myristate acetate (PMA) or phosphatidic acid (PA, the product of PLD-dependent hydrolysis of phosphatidylcholine), significantly enhanced CD44 expression. Conversely, the treatment of F3II cells with H7, a specific PKC inhibitor, or propranolol, which blocks PA conversion to DAG, significantly decreased CD44 expression levels. These results suggest the involvement of PKC and PLD pathways in CD44 expression. These results demonstrate that CD44 plays an important role during F3II cells adhesion, spreading, migration, and invasion. In addition we provide information linking the PLD- and PKC-dependent pathways with the regulation of CD44 expression.
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PMID:Function and expression of CD44 during spreading, migration, and invasion of murine carcinoma cells. 968 38

Prior studies by our laboratory have shown that 1, 25-dihydroxyvitamin D3 activated PKC-alpha, but not PKC-delta, -epsilon, or -zeta, in normal rat colonocytes. In the present studies we demonstrate for the first time that this secosteroid also activated PKC-betaII, another DAG- and Ca2+-dependent PKC isoform recently shown to be present in these cells. Moreover, this activation of PKC-betaII by 1,25-dihydroxyvitamin D3 treatment of isolated colonocytes was shown to be lost in cells from vitamin D-deficient rats and, at least partially, restored by repleting these animals with this secosteroid for 7 days. Under basal conditions, the expression of PKC-alpha and -betaII in brush-border membranes was comparable to their respective expression in basolateral plasma membranes of rat colonocytes. In contrast, the expression of PKC-delta was significantly greater in brush-border membranes, whereas PKC-epsilon and -zeta were enriched in the basolateral plasma membranes. Furthermore, 1,25-dihydroxyvitamin D3 specifically induced the translocation of PKC-betaII, but not PKC-alpha, to the basolateral, but not brush-border plasma membranes of rat colonocytes, via a pp60(c-src)-dependent mechanism.
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PMID:1,25-Dihydroxyvitamin D3 targets PKC-betaII but not PKC-alpha to the basolateral plasma membranes of rat colonocytes. 973 29

The replacement of the sn-1 and sn-2 carbonyl esters in DAG-surrogate lactones by sulfonate esters showed that their isosteric properties in protein kinase C binding are controlled by the location of the hydrophobic alkyl chain on the molecule. The CO and SO2 groups appear to be true isosteres only when they are adjacent to the alkyl chain, which is presumed to insert normal to the lipid bilayer.
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PMID:Conformationally constrained analogues of diacylglycerol (DAG). 14. Dissection of the roles of the sn-1 and sn-2 carbonyls in DAG mimetics by isopharmacophore replacement. 987 29

Since there have been very few studies on nucleolar signaling, an attempt was made to establish nucleolar signal pathways which link the cell membrane to the nucleolus for the transfer of extracellular signals. Two pathways were studied. One was the G alpha s mediated cAMP pathway where two signal molecules were yielded, including RII and protein kinase A. The other was the G alpha q mediated DAG/IP3 pathway which yields two signals including protein kinase C and IP3/Ca2+. By the studying isolated nucleoli from resting liver, regenerating liver or weak carcinogen thioacetamide treated liver, it was possible to detect protein kinase A (PKA), protein kinase C (PKC) and RII subunits. In addition, CK2 was detected. It was found that external signals transmitted through G protein coupled receptors could reach into the nucleolus and that physical translocation of signal molecules was an integral step involved in membrane-nucleolus linked pathways. When an in vitro assay of the above signal molecules was carried out using [gamma-32P]-ATP, most kinase dependent phosphorylation was via the major CK2 (more than 95%). Therefore, it is suggested that the major CK2 dependent pathway is involved in 'house keeping' for nucleolar integrity and the minor pathways, dependent on PKA, PKC and others, are involved in subtle regulatory mechanisms such as 'extra-house-keeping' activities by nucleolar chromosomal remodeling.
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PMID:Nucleolus contains signal molecules that constitute membrane-nucleolus linked pathway. 989 50

The mechanism of arginine vasopressin (AVP)-induced arachidonic acid (AA) release was examined in the cardiac myoblast cell line, H9c2. Stimulation of cells with AVP induced dose-dependent AA release, and this effect was completely inhibited by the V1 receptor antagonist, d(CH)5[Tyr(Me)2]AVP. AVP also produced dose-dependent stimulation of inositol phosphate formation; this was not affected by pertussis toxin, indicating the presence of the V1 receptor/Gq protein/PLCbeta pathway in H9c2 cells. The concentration-response curves for these two effects of AVP overlapped. AVP induced a rapid increase in [Ca2+]i, followed by a sustained increase. The Ca2+ ionophore, A23187 or ionomycin, mimicked the effect of AVP, whereas the protein kinase C (PKC) activator, TPA, only induced a slight increase in AA release. Both the AVP- or A23187-stimulated AA release and the AVP-induced sustained [Ca2+]i increase were completely blocked in the absence of external Ca2+. The receptor-operated Ca2+ channel blocker, SKF 96365, and the inorganic Ca2+ channel blockers, Ca2+ and Ni2+, also inhibited the AVP-induced AA release. Western blots demonstrated expression of PKCalpha, betaI, epsilon, delta, and zeta in H9c2 cells; PKC inhibitors (staurosporine or Ro 31-8220) or down-regulation of PKCalpha, betaI, epsilon, and delta by long-term (24 h) TPA treatment caused a partial blockade of the AVP-induced response, whereas the A23187-induced AA release was unaffected by down-regulation of these isoforms. AVP-induced, but not A23187-induced, AA release was partially blocked by the p42 MAPK cascade inhibitor, PD 98059. AVP and TPA, but not A23187, induced an increase in activity and tyrosine phosphorylation of p42 MAPK, together with a molecular weight shift, consistent with phosphorylation, of cytosolic PLA2. AVP- or TPA-induced activation and tyrosine phosphorylation of p42 MAPK were completely blocked by down-regulation of PKCalpha, betaI, epsilon, and delta, but still occurred, together with the cytosolic PLA2 mobility shift, in the absence of external Ca2+. These results show that AVP-induced AA release in H9c2 cells is secondary to activation of the V1 receptor/Gq protein/PLCP pathway, leading to an influx of extracellular Ca2+ and activation of PKCalpha, betaI, epsilon, and delta. The influx of extracellular Ca2- and DAG act, respectively, through PKC-/MAPK-independent or PKC-dependent MAPK pathways to mediate AA release.
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PMID:Signal transduction of arginine vasopressin-induced arachidonic acid release in H9c2 cardiac myoblasts: role of Ca2+ and the protein kinase C-dependent activation of p42 mitogen-activated protein kinase. 1009 98

A serious insulin resistance characterizes pancreatic cancer-associated diabetes mellitus. Elsewhere, we demonstrated that MIA PaCa2 cultured cells secrete a soluble factor responsible for reduced glucose tolerance induced in SCID mice. The intracellular mechanism of insulin resistance was investigated in isolated and perfused rat hepatocytes incubated with MIA PaCa2 conditioned medium. Lactate production was reduced compared to hepatocytes incubated with control medium while 1,2-DAG was increased and PKC was activated in the hepatocytes incubated with MIA PaCa2 conditioned medium. This behavior was not reproduced treating the hepatocytes with the growth factors EGF, interleukin Ibeta, interleukin-6, and TGF-beta1. In an attempt to make a biochemical identification of the hypothesized tumor associated-diabetogenic factors we observed a low molecular weight protein in the conditioned medium, absent in the nonconditioned one, that may be responsible for the described behaviors.
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PMID:Glucose metabolic alterations in isolated and perfused rat hepatocytes induced by pancreatic cancer conditioned medium: a low molecular weight factor possibly involved. 1019 61


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