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)

To study the role of protein phosphorylation in erythropoietin (EPO)-mediated signal transduction, we examined the effects of tyrosine phosphatase and tyrosine and serine-threonine kinase inhibitors as well as activators of serine kinases on DNA synthesis and cell proliferation in the murine EPO-dependent cell line HCD-57. HCD-57 cells were obtained synchronized in G0 by centrifugal elutriation, and DNA synthesis was measured by incorporation of labeled thymidine into DNA. Half-maximal DNA synthesis was stimulated by 0.001 U/ml of EPO. Sodium orthovanadate (Na3VO4), a tyrosine phosphatase inhibitor, at 5 microM potentiated a subsaturating concentration of EPO. Na3VO4 alone stimulated HCD-57 DNA synthesis at concentrations of 0.1-20 microM. Zinc chloride, another tyrosine phosphatase inhibitor, also stimulated HCD-57 DNA synthesis at concentrations of 50-100 microM. Genistein, a tyrosine kinase inhibitor, blocked the effect of EPO at a concentration of 5 micrograms/ml. Bryostatin, a protein kinase C (PKC) activator, stimulated DNA synthesis in HCD-57 cells at concentrations of 10(-9)-10(-10) M, whereas the phorbol ester, phorbol 12,13-dibutyrate (PDBu), was stimulatory only at a concentration of 10(-11) M. Staurosporine, a PKC inhibitor, blocked the effect of EPO at a concentration of 10(-7) M, and H-7, a nonspecific protein kinase inhibitor, was not inhibitory. These agents also had similar effects on the in vitro proliferation of HCD-57 cells. Taken together, the data indicate that the EPO-mediated transition from G0 to S phase in HCD-57 cells involves the activation of both tyrosine and serine-threonine kinases and is modulated by tyrosine phosphatase activity.
 ...
PMID:Protein kinases and phosphatases are involved in erythropoietin-mediated signal transduction. 131 37

Nerve growth factor-stimulated mitogen-activated protein kinase (pp42/44MAP) kinase was characterized by sequential column chromatography on DEAE-Sephacel, phenyl-Sepharose CL4B, and S-200. The kinase displayed an apparent molecular mass of 42 kDa and reacted with an antiphosphotyrosine antibody. Peptide mapping of myelin basic protein revealed the presence of one phosphopeptide that was phosphorylated on Thr-97. pp42/44MAP kinase activity was dependent on Mg2+ and inhibited by K252a both in vitro and in vivo. Nerve growth factor-stimulated kinase activation was diminished by down-regulation of protein kinase C with 200 nM 12-phorbol 13-myristate acetate or with staurosporine (1 nM), a protein kinase C inhibitor. Genistein, a protein tyrosine kinase inhibitor, blocked nerve growth factor-mediated neurite extension as well as diminished activation of pp42/44MAP kinase. Our data demonstrate that activation of this kinase system by nerve growth factor displays a requirement for both protein kinase C as well as protein tyrosine kinase. In addition, other agents that are capable of promoting neurite outgrowth in PC12 cells, such as fibroblast growth factor or dibutyryl cyclic AMP, do so independently of activating this kinase system.
 ...
PMID:pp42/44MAP kinase is a component of the neurogenic pathway utilized by nerve growth factor in PC12 cells. 132 67

CSV3 clones of simian virus 40 large T antigen-transformed murine 3T3 T cells can be made quiescent as part of a differentiation process. In these quiescent cells, insulin- and vanadate-induced mitogenesis are both associated with the induction of the c-jun proto-oncogene (Wang and Scott 1991 J. Cell. Physiol. 147, 102-110; Wang et al. 1991 Cell Growth Differ. 2, 645-652). The current studies were therefore designed to compare the early signal transduction pathways employed by insulin and vanadate to regulate c-jun expression. In quiescent CSV3-1 cells, down-regulation of protein kinase C by prolonged exposure to 12-O-tetra-decanoylphorbol-13-acetate or inhibition of protein kinase C activity by treatment with the protein kinase C antagonist staurosporine is shown not to affect c-jun induction by insulin or vanadate. This suggests that both insulin and vanadate act in a protein kinase C-independent manner. Insulin's effect on c-jun induction does, however, involve a G protein because insulin's effect can be inhibited by pertussis toxin. In contrast, vanadate induction of c-jun is not affected by pertussis toxin. Genistein, a general tyrosine kinase inhibitor, can inhibit the ability of vanadate to induce c-jun but it does not inhibit insulin's effect. Finally, the depletion of polyamines, particularly spermidine, by DL-alpha-difluoromethylornithine treatment also prevents c-jun induction by insulin but DL-alpha-difluoromethylornithine treatment has no effect on c-jun induction by vanadate. These observations indicate that the c-jun induction by insulin and vanadate in CSV3-1 cells is mediated by different signal transduction mechanisms. Together with our previously published data, these results suggest that c-jun can be induced independent of protein kinase C activation, without involvement of pertussis toxin-sensitive G protein, independent of induction of c-fos, and without expression of high levels of intracellular polyamines.
 ...
PMID:Induction of c-jun independent of PKC, pertussis toxin-sensitive G protein, and polyamines in quiescent SV40-transformed 3T3 T cells. 133 Jun 58

Human interleukin-9 (IL-9) was originally identified and cloned based on its stimulatory effect on proliferation of human myeloid cell line, M07e. IL-9 synergized with Steel factor, the ligand for the c-kit product, to stimulate M07e cell proliferation. To investigate potential mechanisms for this, IL-9 was assessed for effects on protein tyrosine kinase activities in M07e cells by immunoblotting with anti-phosphotyrosine monoclonal antibody; results were compared with those of Steel factor alone and in combination with IL-9, and those of 12-0-tetradecanoyl phorbol-13-acetate (TPA). Recombinant human IL-9 (10 ng/mL) rapidly and transiently induced or enhanced at least four tyrosine phosphorylated protein bands with molecular weights of 105, 97, 85, and 81 Kd. This tyrosine phosphorylation pattern was different from that generated by recombinant murine Steel factor or TPA stimulation and the combination of IL-9 and Steel factor did not change the IL-9-induced pattern. IL-9-induced tyrosine phosphorylated bands were completely blocked by treatment of IL-9 with anti-IL-9 antibody under conditions that also neutralized the synergistic effect of IL-9 with Steel factor on M07e cell proliferation. Genistein, a tyrosine kinase inhibitor, blocked phosphorylation of IL-9 and Steel factor-induced bands. Unlike Steel factor or TPA, IL-9 did not appear to stimulate phosphorylation of 42-Kd mitogen-activated protein (MAP) kinase or Raf-1, or enhance MAP kinase activity. MAP kinase and Raf-1 are serine/threonine kinases that are phosphorylated and activated by many growth factors and by agonists for protein kinase C. While the combination of IL-9 plus SLF did not appear to induce phosphorylation of new bands not already seen with either IL-9 or SLF alone, or enhance the phosphorylation of those bands seen with either cytokine alone, the results suggest that IL-9 activates specific and unique signal transduction pathways.
 ...
PMID:Recombinant human interleukin-9 induces protein tyrosine phosphorylation and synergizes with steel factor to stimulate proliferation of the human factor-dependent cell line, M07e. 138 99

Staurosporine, a microbial-derived protein kinase inhibitor, reversibly blocked non-synchronized, replicating cultures of the human lung epithelial cell line EKVX in the G1 phase of cell cycle and inhibited DNA synthesis and cell replication. The mechanism of this cell-cycle arrest in EKVX cells by staurosporine was likely due to inhibition of protein kinase C (PKC) because: 1) dose-dependent inhibition of DNA synthesis occurred at levels of staurosporine that inhibit phosphorylation of PKC substrate, 2) inhibition of DNA synthesis was also seen after treatment with another PKC inhibitor H7, but not by the chemically similar HA1004, which has a relative inhibitory specificity for cAMP-dependent protein kinase, and 3) the DNA synthesis was not inhibited by specific tyrosine kinase inhibitors Genistein and Lavendustin A at concentrations that inhibit tyrosine kinase activity. Removal of staurosporine from cell culture media resulted in a rebound in PKC activity and synchronized DNA synthesis in EKVX cultures. The reversibility of the inhibition was noted even after 5 days of treatment with staurosporine, and DNA synthesis remained synchronized for at least two rounds of cell replication after removal of staurosporine. Flow cytometric analysis confirmed that more than 90% of the cell population was blocked in the G1 phase after cells were treated with staurosporine for 24 h. Agents such as staurosporine may be useful for synchronizing cell populations to study cell-cycle specific biochemical events important for the regulation of cell replication in the EKVX cell line.
 ...
PMID:Reversible G1 arrest of a human lung epithelial cell line by staurosporine. 150 20

To evaluate the role of protein phosphorylation reactions in signal transduction of human hepatocyte growth factor (hHGF), now known to be the same protein as the scatter factor and tumor cytotoxic factor, we examined the effects of various inhibitors of protein kinases on the mitogenic activity of hHGF on rat hepatocytes in primary culture. Genistein, a specific inhibitor of tyrosine kinase, dose-dependently inhibited the effect of hHGF in stimulating DNA synthesis of hepatocytes. By contrast, 1-(5-isoquinolinesulfonyl)-2- methylpiperazine (H7), a specific inhibitor of protein kinase C, potentiated the stimulatory effect of hHGF on DNA synthesis of hepatocytes. H7 was effective at over 2 micrograms/ml and potentiated the effect of hHGF over 2-fold at 20 micrograms/ml. On the other hand, an inhibitor of Ca++/calmodulin-dependent protein kinase inhibited both the basal and hHGF-stimulated DNA synthesis in the cells, whereas an inhibitor of cyclic nucleotide-dependent protein kinases had little effect on the action of hHGF. These results suggest that tyrosine phosphorylation is required for stimulation of hepatocyte DNA synthesis by hHGF and that the action of hHGF is negatively regulated by protein kinase C activation.
 ...
PMID:Effects of protein kinase inhibitors on the mitogenic activity of human hepatocyte growth factor on rat hepatocytes in primary culture. 153 55

Addition of ionophore A23187 to washed human platelets caused a time- and dose-dependent increase in the phosphotyrosyl content of 135, 124 and 76 kDa proteins. Platelets loaded with intracellular Ca2+ chelator 5,5'-demethyl-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid before addition of A23187 exhibited no protein-tyrosine phosphorylation. Replenishment of such platelets with extracellular CaCl2 restored A23187-induced protein-tyrosine phosphorylation. Upon stimulation with A23187, both aspirin and ADP scavengers-treated platelets exhibited protein-tyrosine phosphorylation without phosphoinositide hydrolysis or protein kinase C activation. Its protein-tyrosine phosphorylation was not inhibited by ML-9, a selective inhibitor of myosin light chain kinase. Genistein, a selective inhibitor of protein-tyrosine kinase, inhibited A23187-induced platelet aggregation but not secretion. These data show (a) that A23187 stimulates protein-tyrosine phosphorylation by elevation of intracellular Ca2+, (b) that A23187-induced protein-tyrosine phosphorylation is independent of formation of endoperoxides/thromboxane A2, released ADP, phosphoinositide hydrolysis, protein kinase C activation, fibrinogen binding and myosin light chain kinase, and (c) that A23187-induced protein-tyrosine phosphorylation may be involved in platelet aggregation but not in secretion. Furthermore, a synergistic effect of A23187 and protein kinase C activators in stimulating protein-tyrosine phosphorylation is suggested.
 ...
PMID:[Protein-tyrosine phosphorylation of human platelets and its function]. 161 80

Platelet-activating factor (PAF) is a proinflammatory lipid that has platelet-stimulating property. PAF receptor-coupled activation of phosphoinositide-specific phospholipase C (PLC) and phosphorylation of several proteins has already been established in our laboratory. To investigate further the molecular mechanism and relationship between activation of PLC and protein phosphorylation, we have used Genistein (a putative inhibitor of tyrosine-specific protein kinases), phosphotyrosine antibody, and phosphoamino acid analysis to probe the involvement of tyrosine kinase in this process. Washed rabbit platelets were loaded with myo-[2-3H]inositol and challenged with PAF (100 nM) after pretreatment with Genistein. PLC-mediated production of radioactive inositol monophosphate, inositol diphosphate, and inositol triphosphate was monitored. PAF alone caused stimulation of PLC activity [( 3H]inositol triphosphate production), whereas pretreatment with Genistein (0.5 mM) diminished PAF-stimulated PLC activity to basal level. Genistein also blocked PAF-stimulated platelet aggregation at this dose. In contrast to Genistein, staurosporine which inhibits protein kinase C, potentiated PAF-stimulated [3H]inositol triphosphate production. Genistein substantially inhibited the combined effects of staurosporine and PAF on inositol triphosphate production. Genistein also reduced PAF-induced phosphorylation of Mr 20,000 and 50,000 proteins. Phorbol 12-myristate 13-acetate-induced Mr 40,000 protein phosphorylation was also affected by Genistein. The above results suggested that Genistein inhibited tyrosine kinase at an early stage of signal transduction by inhibiting PLC. This, in turn, decreased the activation of protein kinase C and, therefore, caused a reduction in Mr 40,000 protein phosphorylation. The inhibition of PLC by Genistein raised the possibility of involvement of tyrosine kinase in PAF receptor-coupled PLC activation. Western blot analysis using monoclonal antibody to phosphotyrosine demonstrated that PAF stimulated the tyrosine phosphorylation of two major proteins of 50,000 and 60,000 molecular weight. When platelets were challenged with PAF after treatment with either Genistein or CV-6209 (a PAF receptor antagonist), the reactivity of these proteins to monoclonal antibody was inhibited. Phosphoamino acid analysis of Mr 50,000 and 60,000 proteins confirmed that PAF increased the phosphorylation of tyrosine residues in both Mr 50,000 and 60,000 proteins and that this was inhibited by Genistein. Thus, PAF caused a receptor-dependent phosphorylation of tyrosine residues on Mr 50,000 and 60,000 proteins. Based on these observations, it is concluded that tyrosine kinase is involved in the PAF receptor-coupled PLC activation and signal transduction mechanism.
 ...
PMID:Platelet-activating factor stimulation of tyrosine kinase and its relationship to phospholipase C in rabbit platelets: studies with genistein and monoclonal antibody to phosphotyrosine. 169 37

Stimulation of T cell antigen receptor (TCR/CD3) following the recognition of peptide-major histocompatibility antigen complex induces phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis. However, the phospholipase C (PLC) enzyme mediating this process has not been identified. We report that PLC gamma 1 protein is expressed in human T cells. It is a phosphoprotein, and the activation of cyclic AMP-dependent protein kinase (PKA) or of protein kinase C (PKC) with forskolin or phorbol ester, respectively, increases the level of phosphorylation. CD3 stimulation of T cells induces tyrosine phosphorylation of PLC gamma 1 and causes 8-10-fold higher yield of PLC activity with anti-phosphotyrosine antibody (APTyr Ab) from activated cells than from non-activated cells. Genistein, an inhibitor of protein tyrosine kinase, decreases this yield of AP-Tyr Ab-bound PLC activity from activated cells and lowers the level of Ca2+ mobilization. Furthermore, phorbol ester and forskolin treatment of cells before CD3 stimulation reduces the level of tyrosine phosphorylation of PLC gamma 1 and the PLC activity associated with APTyr Ab. These results suggest that CD3 stimulation activates PIP2 hydrolysis by inducing tyrosine phosphorylation of PLC gamma 1, which is regulated negatively by PKC and PKA.
 ...
PMID:PLC gamma 1, a possible mediator of T cell receptor function. 183 54

We have examined the effect of bradykinin (BK) and other peptide mediators with related cellular actions on tyrosine phosphorylation in confluent Swiss 3T3 fibroblast cells using an anti-phosphotyrosine antibody. Immunoblots of extracts from cells stimulated with BK showed a major heterogeneous band centered at Mr 120,000. Three phosphorylated protein species were present within this band. The lower of these three phosphoproteins was occasionally present under basal conditions. The detection of this group of phosphoproteins by the antibody was prevented by coincubation with an excess of phosphotyrosine but not with an excess of phosphoserine or phosphothreonine. The BK-promoted increase in phosphorylation was rapid and transient with the peak response apparent following BK exposure for 1 min. The response was dose-dependent with half-maximal effect occurring at 10-30 nM BK. The antagonist Arg0, Hyp3, Thi5,8, D-Phe7-BK completely inhibited the response indicating that BK was acting via a B2 kinin receptor. Bombesin, at 0.1 microM, stimulated an increase in phosphorylation of the 120-kDa group of proteins with the same efficacy as 0.1 microM BK. On the other hand, 1 microM vasopressin was considerably less efficaceous than either of the former agonists. Short-term preexposure to 0.1 microM 12-O-tetradecanoyl-phorbol-13-acetate (1 min), a protein kinase C stimulator, or 30 microM H7 (15 min), a protein kinase C inhibitor, had no significant effect either on the basal or BK-promoted increase in tyrosine phosphorylation of these proteins. BK also stimulated inositol phosphate formation in these cells. Genistein, a tyrosine kinase inhibitor, inhibited BK stimulation of tyrosine phosphorylation. In addition, genistein partially inhibited BK stimulation of inositol phosphate formation. These results show that an increase in tyrosine phosphorylation of a 120-kDa group of proteins is an early protein kinase C-independent cellular signal elicited by both bradykinin and bombesin.
 ...
PMID:Bradykinin and bombesin rapidly stimulate tyrosine phosphorylation of a 120-kDa group of proteins in Swiss 3T3 cells. 201 98


1 2 3 4 5 6 7 8 9 10 Next >>