Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasmin inhibited the biosynthesis of tissue-type plasminogen activator (tPA) antigen by human umbilical vein endothelial cells (HUVEC) in a dose-dependent manner. The amount of tPA antigen found in the 24-h conditioned medium of cells treated with 100 nM plasmin for 1 h was 20-30% of that in the control group. However, in contrast to tPA, such treatment led to a 3-fold increase in plasminogen activator inhibitor (PAI) activity, whereas the amount of PAI type 1 antigen was unchanged. The effects of plasmin on HUVEC were binding- and catalytic activity-dependent and were specifically blocked by epsilon-aminocaproic acid. Microplasmin, which has no kringle domains, was less effective in reducing tPA antigen biosynthesis or enhancing PAI activity in HUVEC. Kringle domains of plasmin affected neither tPA antigen nor PAI activity of the cells. Other proteases including chymotrypsin, trypsin, and collagenase at comparable concentrations did not have a significant effect on the biosynthesis of tPA antigen or PAI activity of HUVEC. Thrombin stimulated the biosynthesis of tPA and PAI-1 antigens by HUVEC. Thrombin also stimulated an increase in the protein kinase activity in HUVEC, whereas plasmin inhibited the protein kinase activity of the cells. It is possible that plasmin regulates the biosynthesis of tPA in HUVEC through the signal transduction pathway involving protein kinase.
...
PMID:Plasmin and the regulation of tissue-type plasminogen activator biosynthesis in human endothelial cells. 138 68

Thrombin, the key regulatory protein of hemostasis, is a potent stimulus for endothelial cell activation, a process implicated in a variety of ischemic, thrombotic, and inflammatory vascular disorders. Activation of the thrombin receptor requires a novel mechanism of receptor proteolysis generating a tethered receptor ligand. Synthetic peptides whose sequences are identical to this newly exposed receptor NH2-terminus reproduce thrombin effects on human and bovine endothelial cell activation. Receptor cleavage by catalytically active alpha-thrombin is tightly coupled to a PI-PLC, with resultant generation of IP3 and DAG, increases in [Ca2+]i, and translocation of PKC (Fig. 3). Both the increase in [Ca2+]i and PKC activation are required for thrombin-stimulated PLA2 and PLD activity, PGI2 synthesis, and barrier dysfunction, the latter occurring as the result of Ca2+ and PKC effects on specific cytoskeletal protein elements and other contractile proteins (Fig. 3). Further investigations are ongoing to identify more clearly not only the precise biochemical intermediates involved in the endothelial cell response to thrombin but also the specific protein kinase systems involved in thrombin-mediated signal transduction in vascular endothelium.
...
PMID:Molecular mechanisms of thrombin-induced human and bovine endothelial cell activation. 140 26

The U937 human monocyte-macrophage cell line was used to examine the effect of thrombin, an ill-defined chemoattractant, on the polymerization of actin, a process essential for cell motility. In differentiated macrophage-like U937 cells, thrombin (0.5-50 units/ml) caused a rapid dose-dependent increase in the formation of filamentous (F-) actin, detected by the staining of F-actin with the fluorescent toxin, 7-nitrobenz-2-oxa-1,3-diazole-phallacidin. In contrast with other chemoattractants such as N-formylmethionyl-leucylphenylalanine or C5a, actin polymerization in response to thrombin occurred via a pertussis-toxin-insensitive G1-(inhibitory G-protein) independent signalling pathway. Further, this response was not affected by the Ca2+ chelator EGTA or by the specific protein kinase C (PKC) inhibitor RO-31-8220. The response to thrombin was not mimicked by the Ca2+ ionophore ionomycin or by the direct PKC activator phorbol 12-myristate 13-acetate. The thrombin response was, however, inhibited by the non-specific protein kinase inhibitor staurosporine. The present results suggest that in U937 cells thrombin stimulates the formation of F-actin via a signalling pathway independent of (i) the activation of PKC, (ii) the mobilization of intracellular Ca2+ and (iii) the activation of Ca(2+)-dependent protein kinases, but dependent on the activation of an undefined staurosporine-sensitive protein kinase.
...
PMID:Thrombin promotes actin polymerization in U937 human monocyte-macrophage cells. Analysis of the signalling mechanisms mediating actin polymerization. 141 54

Secretion of von Willebrand factor (vWf) glycoprotein from storage granules in human umbilical-vein endothelial cells was studied in vitro. Either elevation of intracellular Ca2+ concentration ([Ca2+]i) with a Ca2+ ionophore or activation of protein kinase (PK) C by phorbol 12-myristate 13-acetate caused vWf secretion, and together the agents acted synergistically. However, when vWf release was stimulated by receptor-mediated agonists, selective inhibition of PKC had no effect on histamine-induced secretion and significantly elevated thrombin-induced secretion. Furthermore, ATP, which efficiently elevates [Ca2+]i in these cells, was a very poor effector of vWf release. We conclude that elevation of [Ca2+]i by physiological agonists is necessary for vWf release, but other signalling mechanisms, as yet uncharacterized, but not due to PKC activation, are required for full induction of the secretory pathway.
...
PMID:The roles of protein kinase C and intracellular Ca2+ in the secretion of von Willebrand factor from human vascular endothelial cells. 153 May 95

Thrombin, the key regulatory protein of hemostasis, has been implicated in a variety of important endothelial cell processes closely linked to endothelial signal transduction mechanisms. An initial event, following receptor binding by catalytically active alpha-thrombin, appears to be the activation of a G-protein-coupled, PI-specific PLC, with resultant generation of IP3 and DAG, with increases in [Ca2+]i, and activation and translocation of PKC (Fig. 9). PKC activation results in down-regulation of PLC, as demonstrated by inhibition of agonist-induced increases in [Ca2+]i, whereas PLA2 activity is up-regulated, with a resultant increase in endothelial PGI2 synthesis. Recently, we have demonstrated that activity of membrane-bound, endothelial PLD, is also up-regulated by PKC activation. In addition to its modulatory role in endothelial cell phospholipase activities, PKC activation appears to play a critical role in thrombin-mediated endothelial barrier dysfunction, likely via specific cytoskeletal protein phosphorylation. A temporal relationship between alpha-thrombin-mediated signal transduction and specific cellular responses, such as PGI2 synthesis and barrier dysfunction, can be established (Fig. 2). Further investigations are ongoing to identify more clearly the precise biochemical intermediates involved in the endothelial cell response to thrombin, as well as the role of differential phosphorylation by various protein kinase systems in thrombin-mediated signal transduction in vascular endothelium.
...
PMID:The role of protein kinase C in alpha-thrombin-mediated endothelial cell activation. 157 13

Fibroblasts represent one of the in vivo sites of insulin-like growth factor-I (IGF-I) production. In this study rat dermal fibroblasts in culture were used as a model system to assess the effect of activation of protein kinase-C on the levels of the mRNAs encoding IGF-I and another growth factor, basic fibroblast growth factor (bFGF). IGF-I and bFGF mRNA levels were determined using a solution hybridization/RNase protection assay. Treatment of cells in serum-free medium containing 0.25% BSA (MEM + BSA) with the tumor-promoting phorbol ester phorbol 12-myristate 13-acetate (PMA) decreased IGF-I and increased bFGF mRNA levels in a time- and dose-dependent fashion. The peak effect of 100 nM PMA on IGF-I mRNA levels occurred at 9 h, whereas the peak effect on bFGF mRNA levels occurred after 3 h of incubation. In dose-response studies, half-maximal inhibition of IGF-I mRNA levels was achieved with approximately 0.08 nM PMA, while half-maximal stimulation of bFGF mRNA levels was achieved with approximately 3 nM PMA. Inhibition of protein synthesis with cycloheximide abrogated the effect of PMA on bFGF mRNA levels, but only partially inhibited the effect of PMA on IGF-I mRNA levels. Studies employing sphingosine or staurosporine to inhibit protein kinase-C or preincubation in high doses of PMA to down-regulate protein kinase-C suggested that the effect of PMA on IGF-I and bFGF mRNA levels was mediated by activation of protein kinase-C, although both staurosporine and sphingosine had independent effects on the levels of these mRNAs and down-regulation of protein kinase-C had a sustained effect on IGF-I mRNA levels. Ligands known to activate protein kinase-C were then tested. Treatment of cells with 100 micrograms/ml of the synthetic diacylglycerol 1-oleoyl-2-acetyl-sn-glycerol decreased IGF-I mRNA levels to 25% and increased bFGF mRNA levels to 520% of the level present in cells maintained in MEM + BSA. Treatment of cells with thrombin or bradykinin also decreased IGF-I mRNA levels and increased bFGF mRNA levels, but whereas the effect of thrombin on IGF-I mRNA levels was marked, the effect of bradykinin was minimal, and whereas the effect of thrombin on bFGF mRNA levels was sustained, the effect of bradykinin was transient.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Activation of protein kinase-C differentially regulates insulin-like growth factor-I and basic fibroblast growth factor messenger RNA levels. 160 84

We have examined the phosphorylation and protein kinase activity of p44 mitogen-activated protein kinase (p44mapk) in growth factor-stimulated hamster fibroblasts using a specific antiserum. The activity of p44mapk was stimulated both by receptor tyrosine kinases and G protein-coupled receptors. Detailed kinetics revealed that alpha-thrombin induces a biphasic activation of p44mapk in CCL39 cells: a rapid phase appearing at 5-10 min was followed by a late and sustained phase still elevated after 4 h. Inactivation of alpha-thrombin with hirudin after 30 sec, which prevented DNA synthesis, did not alter the early p44mapk response but completely abolished the late phase. Pretreatment of the cells with pertussis toxin, which inhibits by more than 95% alpha-thrombin-induced mitogenicity, resulted in the complete loss of late phase activity, while the early peak was partially attenuated. Treatment of CCL39 cells with basic fibroblast growth factor also induced a strong activation of p44mapk. Serotonin, which is not a mitogen by its own, had no effect on late phase p44mapk activity, but synergized with basic fibroblast growth factor to induce late kinase response and DNA synthesis. Both early and late phase activation of p44mapk were accompanied by tyrosine phosphorylation of the enzyme. Together, the results indicate that there is a very close correlation between the ability of a growth factor to induce late and sustained p44mapk activation and its mitogenic potential. Therefore, we propose that sustained p44mapk activation is an obligatory event for growth factor-induced cell cycle progression.
...
PMID:Biphasic and synergistic activation of p44mapk (ERK1) by growth factors: correlation between late phase activation and mitogenicity. 160 90

A newly designed cyclic AMP (cAMP) analogue, Sp-5,6-dichloro-1-beta-D- ribofuranosylbenzimidazole-3',5'-monophosphorothioate (Sp-5,6-DCl-cBiMPS), and 8-(p-chlorophenylthio)-cAMP (8-pCPT-cAMP) were compared with respect to their chemical and biological properties in order to assess their potential as activators of the cAMP-dependent protein kinases (cAMP-PK) in intact cells. Sp-5,6-DCl-cBiMPS was shown to be both a potent and specific activator of purified cAMP-PK and of cAMP-PK in platelet membranes, whereas 8-pCPT-cAMP proved to be a potent activator of cAMP-PK and cyclic-GMP-dependent protein kinase (cGMP-PK) both as purified enzymes and in platelet membranes. Sp-5,6-DCl-cBiMPS was not significantly hydrolysed by three types of cyclic nucleotide phosphodiesterases, whereas 8-pCPT-cAMP (and 8-bromo-cAMP) was hydrolysed to a significant extent by the Ca2+/calmodulin-dependent phosphodiesterase and by the cGMP-inhibited phosphodiesterase. The apparent lipophilicity, a measure of potential cell-membrane permeability, of Sp-5,6-DCl-cBiMPS was higher than that of 8-pCPT-cAMP. Extracellular application of Sp-5,6-DCl-cBiMPS to intact human platelets reproduced the pattern of protein phosphorylation induced by prostaglandin E1, a cAMP-increasing inhibitor of platelet activation. In intact platelets, Sp-5,6- DCl-cBiMPS was also more effective than 8-pCPT-cAMP in inducing quantitative phosphorylation of the 46/50 kDa vasodilator-stimulated phosphoprotein (VASP), a major substrate of cAMP-PK in platelets. As observed with prostaglandin E1, pretreatment of human platelets with Sp-5,6-DCl-cBiMPS prevented the aggregation induced by thrombin. The results suggest that Sp-5,6-DCl-cBiMPS is a very potent and specific activator of cAMP-PK in cell extracts and intact cells and, in this respect, is superior to any other cAMP analogue used for intact-cell studies. In contrast with 8-pCPT-cAMP, Sp-5,6-DCl-cBiMPS can be used to distinguish the signal-transduction pathways mediated by cAMP-PK and cGMP-PK.
...
PMID:Characterization of Sp-5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole- 3',5'-monophosphorothioate (Sp-5,6-DCl-cBiMPS) as a potent and specific activator of cyclic-AMP-dependent protein kinase in cell extracts and intact cells. 165 81

The formation of membrane microparticles through vesiculation of the platelet plasma membrane is known to provide catalytic surface for several enzyme complexes of the coagulation system, and to underlie the procoagulant responses elicited with platelet activation. This induced shedding of vesicles from the plasma membrane is most prominent when platelets are activated by the terminal complement proteins, C5b-9, by a Ca2+ ionophore, or by the combination of thrombin plus collagen. Although shown to require elevated [Ca2+], the cellular events that initiate plasma membrane evagination and fusion to form the shed vesicles remain unresolved. To gain additional insight into the cellular events that regulate membrane microparticle formation, we have examined how this process is influenced by the activity of cellular protein kinases. Cytoplasmic [Ca2+] of gel-filtered platelets was increased by membrane assembly of the terminal complement proteins C5b-9 in the presence of selective inhibitors of protein kinase or phosphatase reactions, and resulting microparticle formation was quantitated by fluorescence-gated flow cytometry. Pre-equilibration of the phosphatase inhibitor vanadate into the platelet cytosol increased microparticle formation by as much as 40%, suggesting that vesiculation of the platelet plasma membrane is influenced by the state of phosphorylation of a cellular constituent. By contrast to the stimulatory effects of vanadate, microparticle formation was partially inhibited in platelets treated with the protein kinase inhibitor sphingosine, the myosin light chain kinase inhibitor ML-7, the calmodulin-antagonist W-7, and under conditions of elevated cytosolic concentration of cyclic adenosine monophosphate. These results indicate that complement-induced platelet microparticle formation is influenced by one or more protein kinase(s) as well as by calmodulin, and suggest a role for the platelet myosin light chain kinase or another Ca(2+)-pluscalmodulin-regulated membrane component.
...
PMID:Participation of protein kinases in complement C5b-9-induced shedding of platelet plasma membrane vesicles. 165 68

Thrombomodulin (TM) is an endothelial cell membrane glycoprotein which modulates coagulation via the formation of thrombin-TM complexes. We investigated the human megakaryoblastic cell line (UT-7) for the presence of functional TM on the cell surface and in cell lysates using a specific enzyme-linked immunosorbent assay, a functional assay, and analysis by fluorescent activated cell sorter. We also examined the effect of cyclic nucleotides on TM in UT-7 cells. Quiescent UT-7 cells contained TM protein in cell lysates, but no TM antigen was observed on the cell surface. Dibutyryl cyclic AMP up-regulated TM: UT-7 cells transiently expressed functional TM antigen on the cell surface via de novo synthesis of TM protein resulting from increased TM mRNA levels. In contrast, dibutyryl cyclic GMP did not significantly affect TM antigen levels. The results suggest that megakaryocytes produce TM antigen and protein kinase A are involved in cellular mechanisms of TM expression.
...
PMID:The biosynthesis of thrombomodulin and its enhancement by dibutyryl cAMP in a human megakaryoblastic cell line, UT-7. 166


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

---