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

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

Angiotensin II, catecholamines, and vasopressin are thought to stimulate hepatic glycogenolysis and gluconeogenesis via a cyclic AMP-independent mechanism that requires calcium ion. The present study explores the possibility that angiotensin II and vasopressin control the activity of regulatory enzymes in carbohydrate metabolism through Ca2+-dependent changes in their state of phosphorylation. Intact hepatocytes labeled with [32P]PO43- were stimulated with angiotensin II, glucagon, or vasopressin and 30 to 33 phosphorylated proteins resolved from the cytoplasmic fraction of the cell by electrophoresis in sodium dodecyl sulfate polyacrylamide slab gels. Treatment of the cells with angiotensin II or vasopressin increased the phosphorylation of 10 to 12 of these cytosolic proteins without causing measurable changes in cyclic AMP-dependent protein kinase activity. Glucagon stimulated the phosphorylation of the same set of 11 to 12 proteins through a marked increase in cyclic AMP-dependent protein kinase activity. The molecular weights of three of the protein bands whose phosphorylation was increased by these hormones correspond to the subunit molecular weights of phosphorylase (Mr = 93,000), glycogen synthase (Mr = 85,000), and pyruvate kinase (Mr = 61,000). Two of these phosphoprotein bands were positively identified as phosphorylase and pyruvate kinase by affinity chromatography and immunoprecipitation, respectively. Incubation of hepatocytes in a Ca2+-free medium completely abolished the effects of angiotensin II and vasopressin on protein phosphorylation but did not alter those of glucagon. Treatment of hepatocytes with angiotensin II, glucagon, or vasopressin stimulated phosphorylase activity by 250 to 260%, inhibited glycogen synthase activity by 50%, and inhibited pyruvate kinase activity by 30 to 35% (peptides) to 70% (glucagon). The effects of angiotensin II and vasopressin on the activity of all three enzymes were completely abolished if the cells were incubated in a Ca2+-free medium while those of glucagon were not altered. The results imply that angiotensin II, catecholamines, and vasopressin control hepatic carbohydrate metabolism through a Ca2+-requiring, cyclic AMP-independent pathway that leads to the phosphorylation of important regulatory enzymes.
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PMID:The role of calcium ion as a mediator of the effects of angiotensin II, catecholamines, and vasopressin on the phosphorylation and activity of enzymes in isolated hepatocytes. 22 57

In cultured vascular smooth muscle cells, angiotensin II (Ang II) stimulated a cytosolic protein kinase activity toward myelin basic protein (MBP) in a time- and dose-dependent manner. Phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate also increased the MBP kinase activity. Downregulation of protein kinase C by prolonged treatment of the cells with phorbol 12,13-dibutyrate markedly attenuated the Ang II- and PMA-induced MBP kinase activation. The Ang II- and PMA-stimulated MBP kinase activities were resolved almost equally into two distinct fractions on Mono-Q HR5/5 column chromatography (kinase 1 and kinase 2). The kinase assay in polyacrylamide gel revealed that apparent molecular masses of kinase 1 and kinase 2 were 40 and 45 kd, respectively. Microtubule-associated protein 2 also served as a substrate for both the kinases. Immunoblot analysis with an antiphosphotyrosine antibody suggested that both the kinases were tyrosine-phosphorylated during the action of Ang II. Phosphoamino acid analysis revealed that Ang II and PMA induced phosphorylation of both the kinases on serine/threonine as well as tyrosine residues. Phosphopeptide mapping patterns of kinase 1 and kinase 2 isolated from Ang II-stimulated cells were almost identical with those from PMA-stimulated cells. These results indicate that in vascular smooth muscle cells Ang II activates two species of MBP/microtubule-associated protein 2 kinases mainly through the protein kinase C-signaling pathway and suggest that tyrosine and serine/threonine phosphorylation may be involved in this process.
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PMID:Angiotensin II stimulates two myelin basic protein/microtubule-associated protein 2 kinases in cultured vascular smooth muscle cells. 132 34

Relatively little is known about the regulation of secretion of hypothalamic beta-endorphin, the potent opioid that is believed to play a variety of physiological roles in brain. Previous work has shown that arginine vasopressin (AVP), which acts in brain primarily via activation of the phosphoinositol (PI) second messenger system, stimulates secretion of hypothalamic beta-endorphin. To test the hypothesis that activators of protein kinase C (PKC), which is activated following PI hydrolysis, stimulates secretion of beta-endorphins from hypothalamus, we studied the separate effects of stimulators of PKC including phorbol ester 12-myristate-13-acetate (PMA) and 1-oleolyl-2-acetyl glycerol (OAG- a diacyl glycerol analogue) on secretion of immunoreactive (IR-) beta-endorphin (measured by RIA) from dissociated fetal rat hypothalamic cell cultures. We also studied AVP and angiotensin II (Ang II), hypothalamic peptides which activate the PI second messenger pathway, and interactions of PMA and forskolin (FSK), an activator of the cyclic AMP/protein kinase A (PKA) pathway. PMA, OAG, AVP, and Ang II stimulated IR-beta-endorphin secretion. The stimulatory effect of both PMA and FSK on IR-beta-endorphin secretion was greater than that of PMA or FSK alone and was essentially additive.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protein kinase C activators stimulate beta-endorphin secretion from hypothalamic cells. 142 53

The effect of enalapril and angiotensin II on junctional conductance (gj) of isolated rat heart cell pairs was investigated. It was found that enalapril (1 micrograms/ml) increases gj by 106 +/- 3.1% (SEM) (n = 20) within 4 min. The effect of enalapril on gj was not suppressed by propranolol (10(-6) M) or by a cAMP-dependent protein kinase inhibitor. Angiotensin II (1 micrograms/ml) reduced gj by 55%. These observations might indicate that an intrinsic renin-angiotensin system in heart is involved in the control of gj in cardiac muscle.
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PMID:Enalapril, an inhibitor of angiotensin converting enzyme, increases the junctional conductance in isolated heart cell pairs. 172 43

Angiotensin II (Ang II) belongs to the family of the calcium-mobilizing hormones which includes other vasoactive hormones such as vasopressin, endothelin, serotonin. Angiotensin can be considered as an archetype for ligands activating the calcium messenger system. Observation of the changes occurring in the two branches of the calcium messenger system--the inositol 1, 4, 5-trisphosphate/calcium branch and the diacylglycerol/protein kinase branch--upon activation by Ang II in various target cells (adrenal zona glomerulosa cells, vascular smooth muscle cells and cardiomyocytes) emphasized common features but also revealed variation in the responses and in the interaction between the two branches (so-called cross-talk). For example, the use of single cell microfluorometry with fura-2 shows that, in adrenal glomerulosa cells, Ang II induces sinusoidal oscillations of cytosolic free calcium concentration which are typical of excitable cells; by contrast in vascular smooth muscle cells, one observes transient oscillations indicative of a mechanism of calcium-induced calcium release. Furthermore, the activation of protein kinase C by angiotensin II leads to negative feed-back mechanisms on the final biological response in adrenal cells and cardiomyocytes, whereas it has a potentiating effect in vascular smooth muscle cells. On-line video microscopy allows one to follow in real time the changes in cytosolic free calcium concentration in vascular smooth muscle cells and spontaneous beating cultured cardiomyocytes thereby revealing the spatial origin of the calcium "tide" spreading throughout the cytosol. The task is now to superimpose these calcium signals, these biochemical triggers and the framework of the cytoskeleton and intracellular organelles forming the stage of this play.
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PMID:[Transmembrane signal. Respective role of free cytosol calcium and of protein kinase C]. 182 87

We have previously shown that recombinant interleukin 1 (IL-1) and recombinant tumour necrosis factor (TNF) synergistically stimulate phospholipase A2 release from mesangial cells. We now report that treatment of mesangial cells with the beta-agonist salbutamol, prostaglandin E2 (PGE2), cholera toxin or forskolin, which all activate adenylate cyclase, increased release of phospholipase A2 activity. Likewise, addition of a membrane-permeant cyclic AMP (cAMP) analogue or the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine enhanced release of phospholipase A2 activity from mesangial cells. There was a lag period of about 8 h before a significantly enhanced secretion could be detected. Furthermore, actinomycin D or cycloheximide completely suppressed cAMP-stimulated secretion of phospholipase A2. Angiotensin II, the phorbol ester phorbol 12-myristate 13-acetate, the Ca2+ ionophore A23187 and a membrane-permeant cGMP analogue did not stimulate phospholipase A2 release from the cells. Treatment with indomethacin completely inhibited IL-1 beta- and TNF-stimulated PGE2 synthesis, without having any effect on phospholipase A2 secretion, thus excluding cytokine-induced PGE2 synthesis as the mediator of phospholipase A2 release. Neither IL-1 beta nor TNF induced any increase in intracellular cAMP in mesangial cells. Furthermore, incubation of the cells with 2',5'-dideoxyadenosine, an inhibitor of adenylate cyclase, did not block cytokine-stimulated phospholipase A2 secretion. In addition, IL-1 beta and TNF synergistically interacted with forskolin to stimulate phospholipase A2 release from the cells. The protein kinase inhibitors H-8, staurosporine, K252a and amiloride inhibited IL-1 beta- and TNF-stimulated phospholipase A2 secretion. However, high concentrations that inhibit other protein kinases were needed. These observations suggest that IL-1 beta and TNF cause secretion of phospholipase A2 by a mechanism independent of cAMP. The signalling pathways used by IL-1 beta and TNF may involve a protein kinase that is probably different from protein kinase A or protein kinase C.
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PMID:Cyclic AMP mimics, but does not mediate, interleukin-1- and tumour-necrosis-factor-stimulated phospholipase A2 secretion from rat renal mesangial cells. 184 28

Angiotensin II acts on adrenal glomerulosa cells to induce the phospholipase C-mediated generation of inositol trisphosphate and sn-1,2-diacylglycerol as the major products of inositol phospholipid breakdown. This last product is known to activate protein kinase C, but its role in the action of angiotensin II on steroidogenesis has not been defined. We report herein that, in bovine adrenal glomerulosa cells, protein kinase C activators, such as phorbol 12,13-dibutyrate, 12-O-tetradecanoylphorbol-13-acetate, mezerein and sn 1,2 oleoyl acetoylglycerol, each failed to increase steroidogenesis. These results contrast with our recent report on the enhancement of aldosterone output by sn-1,2-dioctanoylglycerol (DiC8) [J. Steroid Biochem. 35 (1990) 19-33]. In addition, the difference between DiC8 and the other protein kinase activators was also observed in the pattern of 86Rb efflux from preloaded glomerulosa cells; only DiC8 mimicked the effect of angiotensin II on ion fluxes. Furthermore, staurosporine, a potent inhibitor of protein kinase C, was capable of amplifying the aldosterone output induced by a maximally effective concentration of DiC8 or angiotensin II. These data suggest that the effect of the cell permeant DiC8 on aldosterone biosynthesis either is not mediated by protein kinase C activation, or is mediated by a phorbol ester-insensitive isoenzyme of protein kinase C.
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PMID:Contrasting effects of sn-1,2-dioctanoyl glycerol as compared to other protein kinase C activators in adrenal glomerulosa cells. 191 21

Calmodulin-dependent protein phosphatase from bovine brain and heart was assayed for phosphotyrosine and phosphoserine phosphatase activity using several substrates: 1) smooth muscle myosin light chain (LC20) phosphorylated on tyrosine or serine residues, 2) angiotensin I phosphorylated on tyrosine, and 3) synthetic phosphotyrosine- or phosphoserine-containing peptides with amino acid sequences patterned after the autophosphorylation site in Type II regulatory subunit of the cAMP-dependent protein kinase. The phosphatase was activated by Ni2+ and Mn2+, and stimulated further by calmodulin. In the presence of Ni2+ and calmodulin, it exhibited similar kinetic constants for the dephosphorylation of phosphotyrosyl LC20 (Km = 0.9 microM, and Vmax = 350 nmol/min/mg) and phosphoseryl LC20 (Km = 2.6 microM, Vmax = 690 nmol/min/mg). Dephosphorylation of phosphotyrosyl LC20 was inhibited by phosphoseryl LC20 with an apparent Ki of 2 microM. Compared to the reactions with phosphotyrosyl LC20 as the substrate, reactions with phosphotyrosine-containing oligopeptides exhibited slightly higher Km and lower Vmax values. The reaction with the phosphoseryl peptide based on the Type II regulatory subunit sequence exhibited a slightly higher Km (23 microM), but a much higher Vmax (4400 nmol/min/mg) than that with its phosphotyrosine-containing counterpart. Micromolar concentrations of Zn2+ inhibited the phosphatase activity; vanadate was less potent, and 25 mM NaF was ineffective. The study provides quantitative data to serve as a basis for comparing the ability of the calmodulin-dependent protein phosphatase to act on phosphotyrosine- and phosphoserine-containing substrates.
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PMID:Characterization of the phosphotyrosyl protein phosphatase activity of calmodulin-dependent protein phosphatase. 242 55

Rat pheochromocytoma (PC12) cells contain specific plasma membrane receptors for both epidermal growth factor (EGF) and nerve growth factor (NGF). Whereas EGF addition to PC12 cells causes a persistent enhancement of proliferation. NGF addition induces a transient stimulation of growth, followed by growth arrest and neuronal differentiation. Despite these differences in biological response, EGF and NGF share a number of early receptor-mediated responses, which are likely te be related to their effect on cell proliferation. In this paper we show that EGF, but not NGF, is able to stimulate the phosphorylation of membrane proteins. In addition, EGF was able to stimulate phosphorylation of a synthetic peptide (RR-SRC) by PC12 membranes in a concentration-dependent manner. Kinetic analysis of the phosphorylation reaction indicated that EGF increased the Vmax from 13 to 70 pmoles/min/mg protein, while no change was observed in Km. Furthermore, EGF was able to stimulate tyrosine phosphorylation of angiotensin I and II, to the same extent as RR-SRC. In contrast no effects of NGF on peptide phosphorylation by PC12 membranes were observed. Cross-linking experiments demonstrated the presence of receptors for both NGF and EGF in PC12 membranes. These different effects of NGF and EGF on activation of membrane-associated protein-kinase activity demonstrate that NGF might be able to stimulate growth transiently without stimulating protein kinase activity.
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PMID:Epidermal growth factor, but not nerve growth factor, stimulates tyrosine-specific protein-kinase activity in pheochromocytoma (PC12) plasma membranes. 300 Apr 61

Congestive heart failure is a complex physiopathological state where both myocardial hypo-contraction and excessive peripheral vasoconstriction lead to lower cardiac output. The increase in cytosolic calcium concentration triggers the contractile processus. Digitalis inhibits the Na+/K+ ATPase enzyme and indirectly increases intracellular calcium concentration. beta 1 agonists increase the synthesis of cAMP-dependent protein kinase and hence the recruitment of new receptor-operated calcium channels which increase the calcium influx and the mobilization from its intracellular storage sites. Vascular smooth muscle contraction occurs with calcium influx into the cell resulting from various receptor activation. In congestive heart failure, activation of the sympathetic nervous system and of the renin-angiotensin system leads to neurohumoral-induced peripheral vasoconstriction. Renal effects of angiotensin II and aldosterone are responsible for sodium and water retention. alpha 1-blocking agents are drugs that block competitively the catecholamines effects on vascular receptors. Angiotensin I-converting-enzyme inhibitors block the formation of the key-element of the system: angiotensin II. Both alpha 1-blocking agents and converting-enzyme inhibitors show vasodilatator effects and acutely improve hemodynamic status of patients with congestive heart failure. Converting-enzyme inhibitors exhibit specific improvement of intrarenal hemodynamics and do not induced sodium and water retention in longterm therapy.
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PMID:[Pharmacological bases of the treatment of cardiac insufficiency]. 303 68


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