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)

Scatter factor (SF) is a cytokine that causes cohesive epithelial colonies to 'scatter' into isolated cells and stimulates epithelial cell migration. To investigate SF's mechanism(s), we screened agents that modulate various intracellular processes for effects on scattering of Madin-Darby canine kidney (MDCK) cells. Selected agents were studied in quantitative migration assays using microcarrier beads. Agents that activate the adenylate cyclase (AC) pathway caused mild to moderate inhibition of scattering and migration, while modulators of Ca2+/calmodulin pathways had little effect on scattering. In contrast, phorbol esters (PMA, PDD) and protein kinase C (PKC) inhibitors (staurosporine, H-7, 7,8-dihydroxychlorpromazine) markedly enhanced and accelerated scattering; PMA and staurosporine also stimulated migration. Diacylglycerol analogues (e.g. diC8), naphthalenesulfonamide PKC activators (SC-9, SC-10) and inactive phorbol esters (e.g. 4a-PDD) did not potentiate scattering, while PKC depletion by 48 h pre-incubation with PMA markedly stimulated scattering. Thus, PMA-enhanced scattering may be related to down-modulation of PKC. Scattering was blocked by inhibitors of protein and RNA but not DNA synthesis; SF- and agent-stimulated migration were ablated by cycloheximide. Scattering and migration were inhibited by an anti-microfilament (cytochalasin B) but not anti-microtubule (e.g. colcemid) agents. These findings suggest that SF-induced epithelial mobility may be mediated, in part, by protein synthesis, alterations in protein phosphorylation (?inhibition of PKC), and actin filament reorganization. They indicate directions for further studies.
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PMID:Studies on the mechanism of scatter factor. Effects of agents that modulate intracellular signal transduction, macromolecule synthesis and cytoskeleton assembly. 170 77

Transforming growth factor-beta 1 (TGF-beta 1) rapidly increases the expression of junB transcription factor and plasminogen activator inhibitor-1 (PAI-1) and prevents the cell cycle-dependent phosphorylation of the RB retinoblastoma susceptibility gene product during late G1 phase in Mv1Lu lung epithelial cells. These responses are shown in this report to be blocked by the potent serine/threonine protein kinase inhibitor, H7, added with TGF-beta 1. Added alone, H7 does not alter the basal junB or PAI-1 mRNA levels, the deposition of PAI-1 into the extracellular matrix, or the phosphorylation of RB in late G1 phase, suggesting that this inhibitor does not have a general nonspecific effect on the cell. The analogs H8 and H9, which are preferential inhibitors of cyclic nucleotide-dependent protein kinases, are fivefold less potent than H7 as inhibitors of the TGF-beta response. The PAI-1 response to TGF-beta 1 is not affected by the simultaneous addition of staurosporine, which is a protein kinase C inhibitor, or by the prolonged preincubation of cells with phorbol 12-myristate 13-acetate, which down-regulates protein kinase C. The results suggest the possibility that H7 and its analogs block various early TGF-beta responses by inhibiting a protein serine/threonine kinase(s).
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PMID:Evidence for the involvement of protein kinase activity in transforming growth factor-beta signal transduction. 172 3

The expression of mRNA coding for IL-1 alpha and IL-1 beta was examined in human peripheral blood monocytes (PBM) to determine if the two genes are under the same mechanisms of transcriptional control and whether or not they can be regulated independently. In response to E. coli lipopolysaccharide (LPS), PBM express approximately 10-fold more IL-1 beta-specific mRNA than IL-1 alpha. However, treatment of these cells with phorbol myristate acetate (PMA) resulted in the expression of IL-1 beta mRNA. Likewise, treatment of PBM with phorbol dibutyrate (PdBu), phorbol diacetate (PDA), or mezerein, which, similar to PMA, were able to induce the translocation of protein kinase C (PKc) to the monocyte plasma membrane, resulted in predominantly IL-1 beta mRNA expression. The inactive tumor promoter 4 alpha-phorbol didecanoate (4 alpha-PDD) did not cause the translocation of PKc or induce the expression of either form of IL-1 mRNA. Following 18 h pretreatment with PMA to downregulate PKc activity, LPS was capable of inducing the expression of both forms of IL-1 mRNA, demonstrating that at least part of the response of PBM to LPS is PKc independent. These results suggest that the activation of PKc alone is sufficient to induce a high level expression of IL-1 beta but not IL-1 alpha mRNA. Furthermore, the possibility exists that another, as yet unknown, signal transduction mechanism is involved in inducing the expression of both IL-1 alpha and IL-1 beta mRNA in response to LPS.
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PMID:Differential regulation of interleukin-1 alpha and interleukin-1 beta mRNA expression in human monocytes: evidence for protein kinase C-dependent and -independent pathways. 176 43

Scatter factor (SF) is a fibroblast-derived cytokine which stimulates motility of epithelial and vascular endothelial cells. We used a quantitative assay based on migration of cells from microcarrier beads to flat surfaces to study the regulation of motility in bovine brain endothelial cells (BBEC). Peptide growth factors (EGF, ECGF, basic FGF) did not stimulate migration. Tumor promoting phorbol esters (PMA, PDD) markedly stimulated migration, while inactive phorbol esters (4a-PDD, phorbol-13,20-diacetate) did not affect migration. Both SF- and PMA-stimulated migration were inhibited by 1) TGF-beta; 2) protein kinase inhibitors (e.g., staurosporine, K-252a); 3) activators of the adenylate cyclase signaling pathway (e.g., dibutyryl cyclic AMP, theophylline); 4) cycloheximide; and 5) anti-cytoskeleton agents (e.g., cytochalasin B, colcemid). However, PMA and SF pathways were distinguishable: 1) PMA induced additional migration at saturating SF concentrations; 2) the onset of migration-stimulation was immediate for PMA and delayed for SF; and 3) down-modulation of protein kinase C (PKC) ablated PMA but not SF responsiveness. Assessment of PKC by (3H)-phorbol ester (PDBu) binding and by immunoblot showed 1) scatter factor does not cause significant redistribution or down-modulation of PDBu binding or alpha-PKC; and 2) PDBu mediates redistribution and down-modulation of both binding and alpha-PKC. These findings suggest two pathways for BBEC motility: a PKC-dependent pathway and an SF-stimulated/PKC-independent pathway.
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PMID:Regulation of motility in bovine brain endothelial cells. 182 64

We have previously shown that arginine vasopressin (AVP) possesses specific binding sites on rat adrenal glomerulosa cells and stimulates phosphoinositide breakdown and accumulation of inositol phosphates (IP) and diacylglycerol. Kinetic experiments also revealed that the production of IP declines rapidly under hormonal stimulation, even in the presence of Ca2+ in the external medium. In the present investigation, we studied the effects of a protein kinase C (PKC) activator phorbol ester (PDBu) on AVP-sensitive accumulation of IP. Experiments were conducted on glomerulosa cells cultured for 3 days. Results show that short term preincubation (5-10 min) with PDBu inhibits AVP-stimulated IP accumulation by 50% (ED50 = 2.6 +/- 0.9 nM). PKC most likely acts on the coupling between AVP receptor and the G-protein since PDBu reduces AVP-sensitive phospholipase C but does not alter either NaF-sensitive phospholipase C, AVP binding, or inositol lipid pools. However, after a 1- or 2-h preincubation with AVP or PDBu, a decrease in both IP accumulation and AVP binding capacity is observed. With regard to aldosterone secretion, PDBu alone stimulates hormone output, but when added simultaneously with AVP, it inhibits AVP-stimulated aldosterone secretion by 70%. If cells are allowed a resting period of 14 h after AVP or PDBu treatment, the AVP response (IP accumulation, AVP binding, and aldosterone output) is recovered and even enhanced. All these effects are specific since the inactive phorbol ester 4 alpha PDD is inactive, and staurosporine (a PKC inhibitor) reverses the PDBu effect. AVP stimulates transiently the translocation of PKC from the cytosol to the membrane, suggesting that the effect observed with PDBu reflects the effect of endogenous PKC stimulated by AVP. These results outline the complexities involved during hormonal stimulation and, at the same time, homologous desensitization phenomena. On one hand, acute treatment with PDBu--which induces PKC activation--is able to stimulate aldosterone secretion but at the same time initiate desensitization, since phorbol ester uncouples the AVP receptor from the coupling G protein. This suggests that PKC may participate in the first step of homologous desensitization. On the other hand, a 2-h incubation with PDBu induces a loss of AVP binding sites. This may represent the second step of homologous desensitization. Finally, a long term treatment with PDBu completely inactivates PKC, hence enabling AVP to further stimulate aldosterone secretion.
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PMID:Involvement of protein kinase C in the coupling between the V1 vasopressin receptor and phospholipase C in rat glomerulosa cells: effects on aldosterone secretion. 183 Feb 69

Protein phosphorylation and dephosphorylation are involved in regulation of cell growth. We tested the hypothesis that the growth inhibitory effect of transforming growth factor beta 1 (TGF-beta 1) involves activation of protein phosphatases. Exposure of human keratinocytes in culture to 400 pM TGF-beta 1 for 48 h led to 80% inhibition of DNA synthesis as measured by nuclear labeling. Incubation of cultured keratinocytes with 400 pM TGF-beta 1 rapidly activated (within 30 min) protein serine/threonine phosphatase, measured using phosphorylase as a substrate. Based on several criteria, including neutralization of activity with specific antibodies and inhibitor-2, TGF-beta 1-activated phosphorylase phosphatase was identified as protein phosphatase 1. TGF-beta 1 did not have rapid effects on protein serine/threonine phosphatase activity (type 2A) measured with histone phosphorylated by protein kinase C or on protein tyrosine phosphatase activity. However, protein tyrosine phosphatase was activated at 48 h, coincident with growth arrest. Differentiation, induced by the combination of TGF-beta 1 plus calcium or by serum, was not accompanied by further serine/threonine or tyrosine phosphatase activation. We conclude that induction of growth arrest in keratinocytes by TGF-beta 1 involves acute activation of protein phosphatase 1, while activation of protein tyrosine phosphatase may represent an additional mechanism for maintaining cells in a growth-arrested state.
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PMID:Growth arrest induced by transforming growth factor beta 1 is accompanied by protein phosphatase activation in human keratinocytes. 184 73

The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) (10 nM) produce a marked reduction in the growth, measured by thymidine uptake, of MCF-7 cells in full growth medium, but had only a small effect on MDA-MB-231 and T47D cells. Bryostatin alone also inhibited growth but to a lesser extent than seen with TPA. The effect of TPA on MCF-7 cells was partially reversed by bryostatin, added simultaneously or after TPA, suggesting bryostatin does not simply mimic TPA in this system. Even though both are believed to act via effects on protein kinase C, bryostatin appears to act as antagonist to the effect of TPA as well as a partial agonist on its own. When the oestrogen receptor positive MCF-7 and T47D cells were maintained in charcoal stripped serum, the increase in DNA synthesis on stimulation with oestradiol was inhibited with 50 nM TPA in MCF-7 cells but not in T47D cells. The effects of these treatments on the expression of two well characterised oestrogen responsive genes pNR2(pS2) and pNR100 (Cathepsin-D) were examined. Rather than preventing transcription of these oestrogen responsive genes, TPA alone increased pNR2 and pNR100 levels in MCF-7 cells and the combined effect of oestradiol and TPA had a marked synergistic effect in increasing the transcript levels of these genes. In T47D cells pNR2 transcripts were not detected and the increase in pNR100 mRNA levels were not affected by TPA. We conclude that the inhibitory effects of TPA on the growth stimulation of MCF-7 cells by oestradiol was not due to a general inhibition of the expression of oestrogen responsive genes. An alternative possibility examined was that the growth inhibitory effect of TPA on MCF-7 cells might be due to stimulation of TGF-beta 1, acting as an autocrine inhibitory growth factor. Oestradiol treatment of MCF-7 cells reduced the levels of TGF-beta 1 mRNA whereas TPA produced a marked increase. The combined effect of TPA and oestradiol further increased TGF-beta 1 mRNA above the levels seen with TPA alone. Bryostatin had little effect on TGF-beta 1 expression either alone or in combination with oestradiol. These observations are consistent with the hypothesis that the inhibitory effect of TPA on MCF-7 cells may be partly due to autocrine inhibition by TGF-beta 1.
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PMID:Phorbol ester and bryostatin effects on growth and the expression of oestrogen responsive and TGF-beta 1 genes in breast tumour cells. 191 Dec 15

Transformation of secondary Sprague-Dawley rat embryo (RE) cells with type 5 adenovirus (Ad5) results in morphologically transformed cells which can undergo a series of sequential changes resulting in enhanced expression of the transformed phenotype, a process termed progression. Selection for a progressed phenotype often occurs after growth in agar or tumor formation in nude mice, and this process is reversible following treatment of cells with 5-azacytidine. In the present study we have analyzed a series of clonal populations of Ad5-transformed RE cells representing different stages in a defined progression lineage. Progression was not associated with alterations in the steady-state levels of mRNA produced by the viral transforming genes, E1A and E1B, or the cellular gene, c-myc. In addition, the tumor-promoting agent 12-O-tetradecanoyl-phorbol-13-acetate (TPA), which induces expression of a progressed phenotype in Ad5-transformed RE cells, did not significantly alter the RNA transcription rates of the Ad5 E1A or E1B genes, the TPA-inducible gene TPA-S1 or the TPA-responsive genes Pro1 or protein kinase C. TPA did, however, increase by 1 h the steady-state level of c-fos mRNA, but this effect was similar in both progressed and unprogressed cells. Progression also did not involve a change in the RNA transcription rate of a number of cellular and viral genes, including actin, c-Ha-ras, c-myc, v-fos, erbB, TGF-alpha, TGF-beta, Pro-2, transin, TPA-R1, v-myb and c-mos, or other adenovirus genes in addition to E1A and E1B, including E2A and E4. Immunoblotting analysis using E1B polyclonal antiserum further indicated that progression was not associated with changes in the levels of an Mr 21,000 polypeptide encoded by E1B. Similarly, immunoprecipitation analysis with an Ad2 E1A monoclonal antibody indicated similar levels of the Mr 55,000 and 48,000 E1A polypeptides, as well as coprecipitated proteins of Mr 300,000, 107,000 and 105,000 [which is the retinoblastoma (Rb) protein], in E11 and E11-NMT cells. Immunoprecipitation of cell lysates with a monoclonal antibody specific for the Mr 105,000 Rb protein further demonstrated that progression also was not associated with a change in the level or state of phosphorylation of the Rb protein. However, transfection of a human Rb gene (also containing a neomycin resistance gene) into Ad5-transformed RE cells was more inhibitory, with respect to formation of G418-resistant colonies, in unprogressed than in progressed Ad5-transformed RE cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Analysis of viral and cellular gene expression during progression and suppression of the transformed phenotype in type 5 adenovirus-transformed rat embryo cells. 192 6

An extensive investigation of the cardiac actions of phorbol esters and the potential role of the Na(+)-H+ exchanger in those actions was carried out using isolated rat hearts. Sixty minutes of perfusion with 10(-9) M phorbol 12-myristate 13-acetate (PMA) or 10(-8) M phorbol 12,13-dibutyrate (PDBu) produced marked cardiac dysfunction associated with depressed contractility, coronary constriction, and elevated resting tension, the latter being particularly evident with PMA. These effects were also associated with disturbances in tissue levels of energy metabolites manifested primarily by a reduction in ATP and an elevation in lactate. Furthermore, both phorbols produced a sustained stimulation of the release of 6-ketoprostaglandin F1 alpha (6-keto PGF1 alpha), the hydrolysis product of prostacyclin (prostaglandin I2). Amiloride, an inhibitor of the Na(+)-H+ exchanger, significantly attenuated the loss in contractility and elevation in coronary pressure as well as the stimulated release of 6-keto PGF1 alpha but was without effect on elevations in resting tension or on changes in energy metabolites. Increasing concentrations of PMA or PDBu 10-fold resulted in a much more rapid and severe (greater than 80% loss in contractile function after 30 minutes) effect that was nonetheless qualitatively identical to that seen with the lower concentrations of phorbol. However, the effects were not prevented by amiloride. Surprisingly, 4 alpha-phorbol 12,13-didecanoate (alpha-PDD, 10(-6) M), which does not activate protein kinase C, was found to be a potent inhibitor of cardiac function (greater than 80% loss in contractility and 50% increase in resting tension) after 30 minutes of perfusion, although these effects were not associated with changes in levels of energy metabolites or with elevations in coronary pressure. Similarly, none of the actions of this compound were attenuated by amiloride. In contrast to the sustained effects of other phorbols on 6-keto PGF1 alpha release, the effect of alpha-PDD was transient (less than 10 minutes). In all hearts studied, the marked depression in contractile function caused by all phorbol esters occurred in the absence of any ultrastructural changes. 4 alpha-Phorbol (10(-6) M), which does not activate protein kinase C, was without effect on any parameter studied. Our results demonstrate very complex effects of phorbol esters on numerous parameters of cardiac function, including an amiloride-sensitive component that occurs at low concentrations. The latter observation suggests the involvement of Na(+)-H+ exchange activation, possibly occurring as a consequence of protein kinase C stimulation, in mediation of the effects of phorbol esters at low concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Concentration-dependent effects of protein kinase C-activating and -nonactivating phorbol esters on myocardial contractility, coronary resistance, energy metabolism, prostacyclin synthesis, and ultrastructure in isolated rat hearts. Effects of amiloride. 193 40

We determined the effects of phorbol 12,13-dibutyrate (PDB), which activates protein kinase C, on pial arteriolar diameter and cerebrospinal fluid (CSF) prostanoid levels in newborn pigs. A closed cranial window was implanted, and the diameter of one pial arteriole was determined by intravital microscopy. In addition, CSF was sampled from under the window, and prostanoid levels (prostaglandin [PG] E2, 6-keto-PGF1 alpha, PGF2 alpha, and thromboxane B2) were determined by radioimmunoassay. Diameter and CSF prostanoid levels were determined during application of artificial CSF containing no drugs and during application of 10(-8), 10(-7), and 10(-6) M PDB. We also determined effects of 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), a phorbol ester that does not activate protein kinase C, and dimethyl sulfoxide, the vehicle for the phorbol esters, on pial arteriolar diameter and CSF prostanoid levels. Initial diameters were 100-200 microns. At 10(-8)-10(-6) M, PDB progressively constricted pial arterioles and increased CSF levels of prostanoids; the other phorbol ester and dimethyl sulfoxide had no such effects. Baseline arteriolar diameter was 147 +/- 17 microns (mean +/- SEM), and diameter was 140 +/- 17 microns at 10(-8) M PDB, 120 +/- 18 microns at 10(-7) M PDB (p less than 0.05), and 108 +/- 14 microns at 10(-6) M PDB (p less than 0.05) (n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of phorbol esters on pial arteriolar diameter and brain production of prostanoids in piglets. 193 55


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