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:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Retinoic acid (RA) induces HL-60 and THP-1 leukemic cell lines to differentiate into granulocyte-like and monocyte-like cells. Limited data are available concerning the effects of RA on components of the cyclic AMP pathway in human myeloid leukemic cells. We showed previously a decrease in adenylate cyclase activity in the presence of histamine, prostaglandin E1 and forskolin in RA-treated HL-60 cells as compared to untreated cells. We examined the elements of the signal transduction pathway utilized by RA in the human myeloid cell line HL-60 and the human monocytic cell line THP-1. We therefore studied the effect of RA on the activity of the stimulatory G-protein (Gs). We demonstrate that addition of RA to two human myeloid leukemia cell lines, HL-60 and THP-1, does not induce a reduction of the 2 subunit of Gs (Gs alpha) RNA or Gs alpha protein in the plasma membrane but leads to a rapid decrease in the cholera toxin (CTX)-catalysed ADP-ribosylation of Gs alpha. In addition, this effect seems to be specific to RA, since there was no modification in Gs alpha ADP-ribosylation in the membranes of cells treated with dimethyl sulfoxide (DMSO), another inducer of differentiation in HL-60 cells.
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PMID:Gs alpha availability to cholera toxin-catalysed ADP-ribosylation is decreased in membranes of retinoic acid-treated leukemic cell lines HL-60 and THP-1. A posttranslational effect. 165 20

We examined the role of augmented formation of intracellular cyclic AMP (cAMP) in the mediation of stromal cell growth factor production that occurs constitutively or upon cytokine stimulation. Clonal murine marrow adherent cell lines were stimulated under serum-free conditions by interleukin-1 (IL-1) or lipopolysaccharide (LPS) and one (+/+ -1.LDA11) was found to produce low quantities of granulocyte macrophage colony-stimulating factor (GM-CSF). GM-CSF identity was confirmed by the ability of supernatants from stromal cells to promote proliferation of the factor-dependent cell line FDC-P1, neutralization of this activity by antiserum to GM-CSF, and by Northern blot analysis. However, optimal concentrations of IL-1 and tumor necrosis factor-alpha (TNF-alpha), in combination, led to synergistic (greater than 5-fold higher quantity) GM-CSF production compared with either stimulus alone in the +/+ -1. LDA11 cell line, capable of GM-CSF production after only single stimulation with IL-1 or LPS. In addition, synergistic stimulation by IL-1 and TNF-alpha led to equivalent high amounts of GM-CSF in another cell line incapable of GM-CSF production after induction with only IL-1 or LPS. Any of several means to raise intracellular cAMP levels, including addition of 8-bromo-cyclic AMP (8Br cAMP) (0.25-1mM), pertussis toxin (20-100 ng/ml), or addition of prostaglandin E1 (PGE1) (1 microM), failed to stimulate GM-CSF production alone and strongly inhibited GM-CSF production in stromal cells stimulated by IL-1, LPS, or the synergistic combination of IL-1 and TNF-alpha. In addition, PGE1 and pertussis intoxication were agonists of adenylate cyclase in membranes of marrow adherent cells, whereas IL-1 and LPS were not. The role for regulators of intracellular cAMP was specific because any of the cAMP agonists alone, or in the presence of cytokine stimulators of stromal cells, strongly enhanced IL-6 production, an event known to be cAMP-responsive. Thus, acute formation of intracellular cAMP is a negative regulator of stromal cell GM-CSF production mediated by cytokines, but positively regulates IL-6 production and may be an important determinant of cytokine-directed marrow microenvironmental function. These findings on the requirement for augmentation versus inhibition of cytokine-mediated production of hemopoietic growth factors might be applied to an analysis of marrow stromal cell heterogeneity.
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PMID:Role for cyclic AMP in the postreceptor control of cytokine-stimulated stromal cell growth factor production. 216 2

Human lymphocyte and granulocyte membranes contain an enzyme, phosphatidylethanolamine N-methyltransferase (PEMT), which catalyzes the transfer of a methyl group from S-adenosylmethionine to the polar head group of phosphatidylethanolamine to form phosphatidylmonomethylethanolamine. This enzyme, in lymphocyte membranes, has Km for S-adenosylmethionine of 7.01 +/- 2.9 (SD) microM, and specific activity 0.57 +/- 0.31 pmol/mg protein/15 min, is inhibited by S-adenosylhomocysteine, displays optimal activity at pH 8.0-9.0, and is stimulated by isoproterenol in dose-dependent, propranolol-inhibitable fashion, to a lesser extent by epinephrine, but not by norepinephrine, prostaglandin E1, concanavalin A, or adenosine 3':5' cyclic monophosphate, with or without phosphodiesterase inhibitors. Granulocyte membrane PEMT has Km for S-adenosylmethionine of 4.4 microM and specific activity 0.54 +/- 0.51 pmol/mg protein/15 min, is inhibited by S-adenosylhomocysteine, displays optimal activity at pH 8.0-9.5, and is stimulated by isoproterenol greater than epinephrine greater than norepinephrine, but not by prostaglandin E1, serum-treated zymosan, formyl-methionyl-leucyl-phenylalanine, or adenosine 3':5' cyclic monophosphate. Because activation of PEMT reportedly contributes to several processes known to be abnormal in cystic fibrosis, including coupling of the beta-adrenergic receptor to adenylate cyclase, activity of PEMT was compared in lymphocyte and granulocyte membrane preparations from cystic fibrosis patients and healthy controls, in which abnormal coupling of beta-adrenergic receptor to adenylate cyclase had been demonstrated. For both cell types, the Km and specific activity of PEMT were comparable in normal and cystic fibrosis samples. Therefore, the hypothesis that reduced PEMT activity accounts for the impaired coupling of beta-adrenergic receptor to adenylate cyclase in lymphocytes and granulocytes in cystic fibrosis is rejected.
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PMID:Lymphocyte and granulocyte phosphatidylethanolamine N-methyltransferase: properties and activity in cystic fibrosis. 302 2

Prostaglandins E(1) and E(2) (PGE(1) and PGE(2)) stimulate adenyl cyclase activity in broken cell preparations of normal human leukocytes, whereas prostaglandin F(1a) produces no effect. PGE(1) and PGE(2) also cause increased accumulation of cyclic 3',5'-adenosine monophosphate-(3)H ((3)H-labeled AMP) in intact leukocytes which have been preincubated with adenine-(3)H in vitro. Theophylline inhibits leukocyte phosphodiesterase activity and potentiates the stimulatory effect of the prostaglandins on intracellular accumulation of cyclic 3',5'-AMP-(3)H. The ability of human granulocytes in vitro to kill Candida albicans was consistently inhibited by PGE(1) and theophylline. This effect was reproduced by dibutyryl cyclic 3',5'-AMP, a lipid-soluble analogue of the endogenous nucleotide. The inhibition of candidacidal activity could not be accounted for by drug effects on phagocytosis, oxygen consumption, or hexose monophosphate shunt activity. These results are consistent with the hypothesis that increased intracellular concentrations of cyclic 3',5'-AMP impair the granulocyte's ability to kill C. albicans, but the precise mechanism of inhibition has not yet been defined.
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PMID:Cyclic 3',5'-adenosine monophosphate in the human lukocyte: synthesis, degradation, andeffects n neutrophil candidacidal activity. 432 28

Recent studies have suggested that cyclic AMP (cAMP) may be involved in regulation of cell growth and differentiation of cancer cells. Incubating HL-60 cells in the presence of the specific H2 agonist dimaprit resulted in 30-fold increases in cAMP levels (EC50 = 5.7 X 10(-6) M) and morphological changes suggestive of cell maturation along the granulocyte pathway. However, cells cultured with 10(-5) M dimaprit showed more than an 80% decrease in their cAMP response to subsequent addition of H2 agonists, whereas the cAMP response to prostaglandin E2 was unaltered. Desensitization was time-dependent (halftime approximately 2.5 hr with 10(-5) M dimaprit), dose-dependent (dimaprit EC50 = 1.4 X 10(-6) M) and completely prevented by 10(-3) M cimetidine. Desensitization of HL-60 cells for 4 hr with 10(-5) M dimaprit followed by the addition of 10(-3) M cimetidine resulted in total recovery of the cAMP response in less than 24 hr. The pharmacologically inactive analog N-methyldimaprit (SK&F 92054) did not increase cAMP production or cause desensitization to H2 stimulation. Desensitization was observed in the presence or absence of a phosphodiesterase inhibitor, indicating that induction of cAMP-phosphodiesterase was not involved in this process. No difference in the number of [3H]tiotidine binding sites was observed between control and dimaprit-desensitized HL-60 cells. Based on these results, we suggest that H2 receptor agonists caused an agonist-dependent desensitization, presumably due to an uncoupling of receptors from adenylate cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Histamine H2 receptor desensitization in HL-60 human promyelocytic leukemia cells. 620 54

The subcellular localization, kinetics of activation, and substrate specificity of the guinea pig granulocyte superoxide (O2-) generating system was investigated. Membrane-enriched particles (podosomes) were made from granulocytes by mild sonication and differential centrifugation. These podosomes are enriched threefold for known plasma membrane markers, 5'-nucleotidase, and adenylate cyclase. Podosomes made from resting granulocytes have very little NAD(P)H-dependent O2- production. Podosomes made from cells stimulated with digitonin are equally enriched for membrane markers but have a 15- to 20-fold increase in NAD(P)H-dependent O2- production. The KmAPP for NADPH is one-tenth that for NADH, but the Vmax is the same. The kinetics of digitonin-stimulated whole-cell O2- production parallel the changes in enzyme activity in these podosomes. Temperature affects both the rate and extent of activation of this enzyme. The pH optimum for the enzyme, the pH optimum for activation, and the pH optimum for whole-cell O2- production are all 7.5. Enzyme activity is increased if the cells are treated with glucose and cyanide, inhibited in cells treated with 2-deoxyglucose (2-DOG), and requires the presence of calcium for activation. These effects are similar to those found for granulocyte O2- production. Thus, the granulocyte O2- generating enzyme system is located on a fraction enriched for plasma membrane markers, and the kinetics of granulocyte production are directly related to the rate and amount of activation of this enzyme.
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PMID:Activation of the guinea pig granulocyte NAD(P)H-dependent superoxide generating enzyme: localization in a plasma membrane enriched particle and kinetics of activation. 624 12

Lymphocytes from patients with cystic fibrosis produce significantly less cAMP in response to beta-adrenergic stimulation than do cells from healthy persons (p less than 0.0005) or patients with bronchiectasis (p less than 0.005). Adenylate cyclase in the basal state or stimulated by GMPPNP or PGE1 is normal, but isoproterenol-stimulated adenylate cyclase activity is significantly (p less than 0.005) reduced in lymphocyte membrane preparations from patients with cystic fibrosis. Granulocytes from patients with cystic fibrosis also produce significantly less cAMP in response to beta-adrenergic stimulation than do cells from healthy subjects (p less than 0.0005) or subjects with bronchiectasis (p less than 0.05). Adenylate cyclase activity in granulocyte homogenates from patients with cystic fibrosis is normal in the basal state or when stimulated by GMPPNP or PGE1 but is significantly (p less than 0.05) reduced compared to normal when stimulated by isoproterenol. These data suggest that the defect is not related to adenylate cyclase itself or to availability of substrate or cofactor to adenylate cyclase, and they may be indicative of a more generalized membrane defect in cystic fibrosis.
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PMID:Adenylate cyclase in leukocytes from patients with cystic fibrosis. 624 8

A method of reproducibility measuring human leukocyte beta-adrenergic receptor density and affinity has been developed and applied to the study of receptor regulation in man. The method has the advantages of using a membrane preparation which binds highly specifically and employing techniques such as using low concentrations of [3H]dihydroalprenol, analyzing the data by computer modelling techniques, and providing data from both granulocytes and lymphocytes in the same individual to minimize measurement errors. Using this methodology, human beta-adrenergic receptor regulation is examined. Cortisone acetate was found to induce an acute rise in granulocyte beta-adrenergic receptor density and adenylate cyclase activity and an acute fall in lymphocyte beta-adrenergic receptor density. This potentially differential regulation of a single receptor subtype in two lines of leukocytes has important implications for the study of receptor regulation in man using leukocyte models.
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PMID:Corticosteroid-induced differential regulation of beta-adrenergic receptors in circulating human polymorphonuclear leukocytes and mononuclear leukocytes. 625 Nov 6

Intact lymphocytes from patients with cystic fibrosis (CF) produce significantly (P less than 0.001) less adenosine 3':5' cyclic monophosphate (cAMP) than normal lymphocytes in response to isoproterenol (10(-8)-10(-4) M), although the basal cAMP content and the response to prostaglandin E1 are normal. Obligate heterozygotes for CF have significantly (P less than 0.005) reduced cAMP response to isoproterenol as well, suggesting a genetic component in the beta adrenergic deficiency in CF. The number of beta adrenergic receptors, as determined by equilibrium binding of [3H]dihydroalprenolol to lymphocyte particulates, is the same in normal lymphocytes (969 +/- 165 receptors/cell) and lymphocytes from patients with CF (1,333 +/- 263 receptors/cell). Binding properties of the receptor for both antagonist and agonist, as assessed by KD for dihydroalprenolol and Ki for (-)-isoproterenol, are also normal in the CF lymphocytes. Similarly, in granulocytes from patients with CF, the cAMP response to isoproterenol (10(-8)-10(-4) M) is significantly reduced compared with healthy controls (P less than 0.03), as is the response of granulocytes from obligate heterozygotes (P less than 0.05). Again, the basal cAMP levels and the response to prostaglandin E1 are normal. The number of beta adrenergic receptors, as determined by equilibrium binding of [3H]dihydroalprenolol to granulocyte particulates, was the same in normal (1,462 +/- 249 receptors/cell) and CF (1,621 +/- 221 receptors/cell) preparations. Binding properties of the receptor for both agonist and antagonist, as assessed by KD for dihydroalprenolol and Ki for isoproterenol, are normal in CF granulocyte particulates. The lymphocyte and granulocyte beta adrenergic defect in CF cannot be explained by abnormalities of the beta adrenergic receptor or of adenylate cyclase itself. Receptor-cyclase coupling is the most likely site of the heritable beta adrenergic defect in CF.
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PMID:Beta adrenergic receptors in lymphocytes and granulocytes from patients with cystic fibrosis. 630 54

In the present study, the expression of beta-adrenergic receptors, the activity of the enzyme adenylate cyclase (AC), and the intracellular concentration of cyclic adenosine 3',5'-monophosphate (cAMP) were investigated in HL-60 cells before and after their differentiation to monocytic or more mature granulocytic cells. Treatment of the HL-60 promyelocytes with 12-O-tetradecanoylphorbol 13-acetate or human interleukin 2 resulted in the appearance of cells with monocytic characteristics (morphology, non-specific esterase, adherence, reaction with a monocyte-specific monoclonal antibody). Induction with retinoic acid resulted in differentiation to cells with typical features of mature granulocytes (morphology, peroxidase, nitro-blue tetrazolium reduction). During maturation to monocytes, the density of beta-adrenergic receptors decreased, whereas it remained constant during maturation to granulocytes. In comparison with normal circulating monocytes or polymorphonuclear granulocytes, expression of beta-adrenergic receptors on the surface of the differentiated HL-60 cells was low. Activation of AC by the hormones isoproterenol, prostaglandin E1, and histamine generally decreased with HL-60 maturation and enzyme activities were markedly below those measured in normal peripheral leukocytes. In the induced monocytic HL-60 cells, the weak effectiveness of isoproterenol was due to the loss of beta-adrenergic receptors. In the induced granulocytic HL-60 cells, the reduced hormonal AC activation could be explained by the impaired coupling between hormone receptors and catalytic enzyme unit. The concentration of intracellular cAMP after differentiation of HL-60 cells reflected the increase in basal AC activity and the decrease in hormone stimulation of the enzyme. Our data indicate that HL-60 cells induced to differentiate possess some monocyte- and granulocyte-like properties, but do not meet several important functional criteria of their new cell identities.
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PMID:[In vitro differentiation of leukaemic promyelocytes (HL-60): effect on beta-adrenergic receptors and adenylate cyclase activity]. 631 Aug 99


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