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)

Bryostatin-1 is a natural activator of protein kinase C and currently examined in phase I trials as anticancer agent. We found that Bryostatin-1 induced tumor necrosis factor alpha (TNF alpha) expression in the human cell line MONO-MAC-6. Using Northern blot analysis and a bioassay for the detection of the cytokine we observed that Bryo alone was sufficient to transiently induce mRNA synthesis and the rapid release of TNF alpha into the culture medium. However, the combination of Bryo with lipopolysaccharide resulted in a strong synergistic increase of TNF alpha secretion. The biologic activity of the secreted TNF alpha was amenable to inhibition by anti-TNF alpha antibodies. Blockade of the lipopolysaccharide receptor CD14 or inhibition of protein kinase C implied that both, CD14 and protein kinase C, are involved individually in signal transduction pathways leading to TNF alpha secretion from MONO-MAC-6 cells. The results demonstrate that Bryostatin-1 is able to induce TNF alpha secretion in human monocytes via a protein kinase C-dependent and CD14-independent pathway and by a mechanism which is most likely based on a strong increase of the TNF alpha mRNA level.
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PMID:The protein kinase C activator Bryostatin-1 induces the rapid release of TNF alpha from MONO-MAC-6 cells. 757 30

The myristoylated alanine-rich C-kinase substrate (MARCKS) is the major protein kinase C (PKC) substrate in many cell types including fibroblasts and brain cells. Here we describe the phosphorylation of MARCKS and the site specificity for different PKC isotypes. Conventional (c)PKC beta 1, novel (n)PKC delta and nPKC epsilon efficiently phosphorylated the MARCKS protein in vitro. The Km values were extremely low, reflecting a high affinity between kinases and substrate. The apparent affinity of nPKC delta (Km = 0.06 microM) was higher than that of nPKC epsilon and cPKC beta 1 (Km = 0.32 microM). The rate of substrate phosphorylation was inversely correlated with affinity and decreased in the order nPKC epsilon > cPKC beta 1 > nPKC delta. Atypical (a)PKC zeta did not phosphorylate the intact MARCKS protein. However, a 25-amino-acid peptide deduced from the MARCKS phosphorylation domain, was efficiently phosphorylated by aPKC zeta as well as by the other three PKC. Site analysis revealed that only serine residues S152, S156 and S163 were phosphorylated, with S163 phosphorylated highest, followed by S156 and S152; in contrast, S160 and S167 were not phosphorylated. No further PKC phosphorylation sites could be detected in MARCKS. The phosphorylation pattern was independent of the type of PKC isotype used. Kinetic analysis showed, that MARCKS is sequentially phosphorylated in the order S156 > S163 > S152 by cPKC, nPKC and aPKC. There was no dramatic difference in the sequential phosphorylation of MARCKS detectable when comparing the four PKC isotypes. The results are discussed in the context of the functional significance of MARCKS phosphorylation.
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PMID:The myristoylated alanine-rich C-kinase substrate (MARCKS) is sequentially phosphorylated by conventional, novel and atypical isotypes of protein kinase C. 758 87

We have investigated coupling between the epidermal growth factor (EGF) receptor and the phospholipase C (PLC)/protein kinase C (PKC) signal-transduction system in normal skin fibroblasts and keratinocytes, for which EGF and transforming growth factor alpha (TGF-alpha) are mitogenic. EGF and TGF-alpha induced a rapid increase in tyrosine phosphorylation of the EGF receptor, in both fibroblasts and keratinocytes, but failed to induce tyrosine phosphorylation of PLC-gamma 1 or detectable phosphoinositide hydrolysis, as measured by two sensitive assays. In fibroblasts, EGF induced phosphatidylcholine (PC) hydrolysis, resulting in increased diacylglycerol (DAG). In contrast, in keratinocytes, there was no detectable PC hydrolysis or elevation of DAG in response to EGF or TGF-alpha. EGF and TGF-alpha activated PKC in fibroblasts, as evidenced by increased phosphorylation of a specific cellular PKC substrate (myristoylated alanine-rich C-kinase substrate, 'MARCKS'). In keratinocytes, TGF-alpha and EGF induced only a modest increase in MARCKS protein phosphorylation. This apparent modest activation of PKC, in the absence of detectable DAG formation, may have been mediated by arachidonic acid, which was released from keratinocytes in response to TGF-alpha, and has been shown to stimulate PKC activity in vitro. These data demonstrate that (1) in dermal fibroblasts and keratinocytes, which express normal levels of EGF receptors, EGF receptor activation is not coupled to tyrosine phosphorylation of PLC-gamma 1 or PtdIns hydrolysis, suggesting that these events are not required for the mitogenic activity of EGF or TGF-alpha in these cells, (2) coupling of EGF receptor to PC hydrolysis is cell-type specific, and (3) in skin fibroblasts, DAG, formed through EGF-induced PC hydrolysis, is capable of activating PKC.
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PMID:Differential induction of phosphatidylcholine hydrolysis, diacylglycerol formation and protein kinase C activation by epidermal growth factor and transforming growth factor-alpha in normal human skin fibroblasts and keratinocytes. 769 May 46

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

Like RIE-1 cells, two of the IEC series of rat intestinal epithelial cell lines were found to express functional angiotensin receptors. As in RIE-1 cells, treatment of IEC-6 or IEC-18 cells with angiotensin II (AII) activated phosphatidylinositol-4,5-bisphosphate (PIP2) hydrolysis although (in contrast to RIE-1 cells) the magnitude of AII-induced PIP2 hydrolysis was small and not associated with a mitogenic response in either IEC cell line. In terms of their other functional responses to AII (activation of protein kinase C (PKC) and a small elevation of cyclic AMP), IEC-6 cells are otherwise similar to RIE-1 cells whereas IEC-18 cells exhibit some phenotypic differences to the other two cell types. Thus, whereas IEC-6 and RIE-1 cells each express the AT1 subtype of angiotensin receptor, the higher affinity receptors on IEC-18 cells are 'atypical', being insensitive to both AT1- and AT2-specific angiotensin receptor antagonists. Furthermore, in contrast to its effects in IEC-6 and RIE-1 cells, AII neither activates PKC nor modulates cyclic AMP levels in IEC-18 cells. Whereas IEC-18 cells express the myristoylated alanine-rich C-kinase substrate (MARCKS), immunoreactive MARCKS was not detected in IEC-6 or RIE-1 cells.
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PMID:Comparison of the responses of three rat intestinal epithelial cell lines to angiotensin II. 792 Mar 81

We analyzed the effect of growth factors on the localization of the 80-kDa acidic myristoylated alanine-rich C-kinase substrate (80-kDa MARCKS), the major protein kinase C (PKC) substrate, in Swiss 3T3 fibroblasts. Virtually all 80-kDa MARCKS of quiescent cultures of these cells was membrane bound. However, within 40 min after addition of bombesin (10 nM) to these cells, the content of 80-kDa MARCKS in the cytoplasmic fraction increased 25-fold. Phosphorylated 80-kDa MARCKS was detectable in the cytoplasmic fraction as early as 30 s after addition of bombesin and the translocation was sustained for 6 h i.e. until 80-kDa MARCKS became down-regulated. The ability of bombesin to stimulate translocation of 80-kDa MARCKS was dose-dependent (concentration required to produce 50% of the effect was 0.6 nM bombesin) and was abolished by the specific antagonist [Leu14,13 psi 14CH2NH]bombesin. Furthermore, platelet-derived growth factor (PDGF) stimulated a dose-dependent (concentration required to produce 50% of the effect was 3 ng/ml) translocation which was comparable to that induced by bombesin in terms of kinetics and magnitude. Translocation was independent of continuous protein synthesis, but dependent on active PKC. Depletion or inhibition of PKC activity abolished the 80-kDa MARCKS translocation induced by either bombesin or PDGF. Furthermore, the neuropeptides beta-endothelin, bradykinin, and vasopressin, which are known to stimulate PKC activity, also promoted translocation. In contrast, epidermal growth factor, insulin and forskolin, which do not activate PKC, failed to cause such an effect. Translocation of 80-kDa MARCKS was also observed in Rat1 cells treated with phorbol ester, PDGF and beta-endothelin. We conclude that the translocation of 80-kDa MARCKS from the membrane to the cytosol is an early response to a variety of growth-promoting factors that stimulate PKC through different signal-transduction pathways.
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PMID:Bombesin, endothelin and platelet-derived growth factor induce rapid translocation of the myristoylated alanine-rich C-kinase substrate in Swiss 3T3 cells. 795 68

To evaluate the question of whether or not insulin activates protein kinase C (PKC), we compared the effects of insulin and phorbol esters on the phosphorylation of the PKC substrate, i.e. myristoylated alanine-rich C-kinase substrate (MARCKS). In rat adipocytes, rat soleus muscle and BC3H-1 myocytes, maximally effective concentrations of insulin and phorbol esters provoked comparable, rapid, 2-fold (on average), non-additive increases in the phosphorylation of immunoprecipitable MARCKS. These effects of insulin and phorbol esters on MARCKS phosphorylation in intact adipocytes and soleus muscles were paralleled by similar increases in the phosphorylation of an exogenous, soluble, 85 kDa PKC substrate (apparently a MARCKS protein) during incubation of post-nuclear membrane fractions in vitro. Increases in the phosphorylation of this 85 kDa PKC substrate in vitro were also observed in assays of both plasma membranes and microsomes obtained from rat adipocytes that had been treated with insulin or phorbol esters. These insulin-induced increases in PKC-dependent phosphorylating activities of adipocyte plasma membrane and microsomes were associated with increases in membrane contents of diacylglycerol, PKC-beta 1 and PKC-beta 2. Our findings suggest that insulin both translocates and activates PKC in rat adipocytes, rat soleus muscles and BC3H-1 myocytes.
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PMID:Effects of insulin and phorbol esters on MARCKS (myristoylated alanine-rich C-kinase substrate) phosphorylation (and other parameters of protein kinase C activation) in rat adipocytes, rat soleus muscle and BC3H-1 myocytes. 821 11

We used the freshwater protozoan Paramecium tetraurelia to investigate the potential regulation by protein kinase C of calmodulin interactions with binding peptides in intact cells. In these organisms, an action potential results in membrane depolarization and a period of backward swimming; repolarization and a return to forward swimming requires the presence of normal calmodulin. We postulated that injection of high-affinity calmodulin binding peptides might interfere with repolarization and thus prolong the period of membrane depolarization. Synthetic peptides spanning the protein kinase C phosphorylation site/calmodulin-binding domains of the myristoylated alanine-rich C-kinase substrate (MARCKS) and the MARCKS-related protein (also known as F52 or MacMARCKS) were injected into cells; these caused a 2- to 3-fold increase in the duration of backward swimming. Similar changes were seen with two other calmodulin-binding peptides. This behavioral response could be prevented by coinjecting calmodulin. Activation of Paramecium protein kinase C with an active phorbol ester completely reversed (within 3 min) the behavioral effects of the normal MARCKS and MARCKS-related protein peptides. Injection of a nonphosphorylatable peptide, in which alanines were substituted for serines, resulted in the usual behavioral response; however, this was not reversed by phorbol ester treatment. The corresponding aspartate-substituted peptide, which has a 10-fold lower affinity for calmodulin, did not prolong backward swimming. These data suggest that these peptides can form complexes with calmodulin at the calcium concentrations that prevail in intact Paramecium cells and that such complexes can be disrupted by protein kinase C phosphorylation of the peptides.
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PMID:Regulation of peptide-calmodulin complexes by protein kinase C in vivo. 843 22

The effect of imprinting, an early form of exposure learning, on the phosphorylation state of the protein kinase C substrates myristoylated alanine-rich C-kinase substrate (MARCKS) and protein F1/43-kDa growth-associated protein (F1/GAP-43) was studied in two regions of the chick forebrain. One region, the intermediate and medial part of the hyperstriatum ventrale (IMHV), is probably a site of long-term memory; the other, the wulst, contains somatic sensory and visual projection areas. After imprinting, a significant increase in MARCKS protein phosphorylation was observed in the left IMHV but not the right IMHV. No significant alteration in F1/GAP-43 was observed in IMHV. MARCKS was resolved into two acidic components of pI approximately 5.0 and approximately 4.0. Phosphorylation of the pI approximately 5.0 MARCKS but not the pI approximately 4.0 MARCKS was significantly altered by imprinting. The partial correlation between preference score (an index of learning) and phosphorylation, holding constant the effect of approach activity during training, was significant only for the pI approximately 5.0 MARCKS in the left IMHV. A significant negative partial correlation between preference score and F1/GAP-43 phosphorylation in the right wulst was observed. Because the imprinting-induced alteration in MARCKS is selective with respect to phosphoprotein moiety, hemispheric location, and brain region, we propose that these alterations may be central to the learning process.
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PMID:Learning selectively increases protein kinase C substrate phosphorylation in specific regions of the chick brain. 846 79

Myristoylated alanine-rich C-kinase substrate (MARCKS), a major substrate of activated protein kinase C (PKC), is thought to be involved in PKC-mediated signal transduction events. In the present study, we have examined the expression of MARCKS in primary cultures of rat glial cells. Western blot analysis of different glial cell types (i.e., astrocytes, oligodendrocytes and microglia) revealed a relatively high level of MARCKS protein in oligodendrocytes. MARCKS protein and MARCKS mRNA levels in oligodendrocytes increased with time in culture, indicating a developmental regulation in MARCKS gene expression in differentiating oligodendrocytes. Immunocytochemical examination of developing oligodendrocytes indicated a strong labeling of MARCKS distributed both in the cell body and in the lacy network of processes. These findings, in concert with our previous observations on the role of PKC in oligodendrogenesis, strongly implicate a PKC-signaling system in oligodendrocyte development.
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PMID:The expression of myristoylated alanine-rich C-kinase substrate in oligodendrocytes is developmentally regulated. 857 45


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