Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cells of the mouse B cell clone, CH12.LX, receive Ag-dependent differentiative signals through their surface membrane class II molecules. The present study was performed to determine the role of class II cross-linking and cAMP in the successful delivery of these signals. Delivery of differentiative signals by anti-Ek mAb was increased by further cross-linking with a secondary anti-isotype antibody. Intact or (Fab')2, but not Fab forms of anti-Ek successfully delivered the Ag-dependent differentiative signal. Inability of monovalent Fab fragments to deliver the signal could not be attributed to an inability to adequately bind Ek molecules. The requirement for cAMP for class II-mediated signaling was also examined, because previous studies have implicated elevated cAMP levels as necessary for class II signaling. Both Ag-dependent, Ek-mediated differentiation and the Ek-mediated inhibition of Ag-independent LPS-induced differentiation were inhibited by the adenyl cyclase inhibitor 2'5'ddA, although elevation of cAMP was not in itself sufficient to deliver the differentiative signal. Inhibition of LPS-induced differentiation could be mediated by mAb binding to either Ek, Abk, or Abb on CH12.LX or an Ab-bearing transfectant, CH12.ABB1. This inhibition was abrogated by 2'5'ddA in the case of Ek or Abb, both of which deliver Ag-dependent differentiative signals to CH12.LX cells. In the case of Abk, which does not deliver such signals to CH12.LX, 2'5'ddA did not abrogate anti-Abk-mediated inhibition of the LPS response. The effects of 2'5'ddA were reversed by the cAMP analog, dibutyryl cAMP, and Ag-dependent-induced differentiation of CH12.LX or CH12.ABB1 was accompanied by an increase in cAMP levels.
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PMID:Requirements of class II-mediated B cell differentiation for class II cross-linking and cyclic AMP. 165 56

Activated macrophages produce a number of proinflammatory cytokines including IL-6, JE, MIP-1 alpha and MIP-1 beta. The induction requirements for production of either IL-6 or the MIP-1 related inflammatory proteins (MIP-1 alpha, MIP-1 beta, and JE) have been analyzed independently using fibroblasts, monocytes, or endothelial cells. However, little is known about the regulation of these cytokines in macrophages. Since activated macrophages produce prostaglandins (PGE2) which may participate in the autoregulation of cytokine production by stimulation of adenylate cyclase and the induction of cAMP-dependent signal pathways, we determined the effects of PGE on the production of IL-6 and MIP-1-related proteins. Murine macrophage cell lines were incubated with PGE1, PGE2, cholera toxin, or dibutyryl cAMP in the presence of absence suboptimal doses of LPS. Pharmacologic agents alone did not induce IL-6 production but incubation of macrophages with combinations of adenylate cyclase stimulators and LPS or dcAMP and LPS led to the dose-dependent enhancement of IL-6 secretion and mRNA expression. In contrast, PGE1 inhibits LPS-induced JE, MIP-1 alpha, and MIP-1 beta mRNA expression and this inhibition is partially dependent on a cAMP-mediated pathway of signal transduction. In previous work we demonstrated that IFN-gamma and PMA do not stimulate the production of IL-6 by macrophages. Here we show that incubation of macrophages with either IFN-gamma or PMA induces the expression of JE, MIP-1 alpha and MIP-1 beta mRNA expression. JE mRNA expression is much more responsive to the stimulatory effects of IFN-gamma than are the MIP-1 genes. Finally, PGE inhibits PMA and IFN-gamma-induced JE and MIP-1-related mRNA expression.
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PMID:Differential regulation of interleukin-6, macrophage inflammatory protein-1, and JE/MCP-1 cytokine expression in macrophage cell lines. 185 Mar 27

Exposure of cultured bovine pulmonary endothelial cells to endotoxin (lipopolysaccharide, LPS) causes cytotoxicity and increased prostacyclin production. Since cyclic nucleotides have been proposed as modulators of inflammation, we wondered whether they were involved in LPS-induced endothelial damage. Bovine pulmonary endothelial cells were exposed for 24 h to LPS and the effects of 1-methyl-3-isobutylxanthine (MIX), a phosphodiesterase inhibitor, dibutyryl cyclic AMP (db-cAMP), forskolin (an adenylate cyclase activator), and sodium nitroprusside (an agent known to stimulate intracellular cyclic GMP generation) on LPS-induced injury were determined. Injury was assessed by measurement of lactate dehydrogenase (LDH) (activity) and prostacyclin (6-keto-PGF1 alpha) in the bathing medium. Incubation with MIX attenuated LPS-induced endothelial cytotoxicity and prostacyclin production in a dose-dependent manner (ANOVA, p less than 0.001). Dibutyryl cyclic AMP also inhibited LPS-stimulated LDH release from the endothelial cells but did not suppress increased prostacyclin production. The combinations of MIX and dibutyryl cyclic AMP produced protection similar to that of MIX alone. Neither nitroprusside nor forskolin affected LPS-induced endothelial injury. Measurements of intracellular cyclic nucleotide concentrations showed that MIX caused marked increases in both cyclic AMP and cyclic GMP within 30 min of incubation, while forskolin and nitroprusside failed to cause such early elevations. Thus, phosphodiesterase inhibition protects endothelial cells from the effects of LPS. Increased intracellular concentrations of cyclic AMP also protect endothelial cells from LPS-induced cytotoxicity but do not alter the prostanoid response. We conclude that increased intracellular concentrations of cyclic AMP protect against LPS-induced endothelial cytotoxicity if present early in the exposure. We further conclude that LPS-mediated endothelial cytotoxicity can be separated from increased prostacyclin production.
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PMID:Attenuation of endotoxin-induced cytotoxicity and prostacyclin production in cultured bovine pulmonary artery endothelial cells by phosphodiesterase inhibition. 246 43

Cholera toxin (CT) is a powerful oral immunogen and adjuvant that elicits strong IgG and IgA antibody responses. In our study we investigated whether this property of CT was associated with an effect on B cell isotype differentiation. Initially, we determined the effect of CT on normal LPS-induced Peyer's patch B cells and found that whereas CT is strongly inhibitory of IgM production, it increases by approximately three-fold the number and frequency of IgG- and IgA-producing cells. Subsequently, using cell sorting technology, we demonstrated that CT acts on membrane (m)IgM+, mIgG/mIgA- B cells rather than mIgG/mIgA+ B cells. In addition, we showed that CT does not cause selective inhibition of mIgM, or enhancement of mIgG/mIgA B cell proliferation. In parallel studies we determined the effect of CT on the differentiation of a clonal B cell population, CH12.LX cells, i.e., a population comprised mainly of mIgM+ cells (98%) admixed with a small subpopulation of mIgA+ cells (2%). Here we found that CT (in the absence of LPS) causes a rapid decrease (24 h) in the intensity of mIgM expression as well as a marked increase in the size of the subpopulation expressing mIgA. In addition, we found that CT (in the presence of LPS), inhibits CH12.LX IgM production while increasing the absolute number and frequency of IgA-producing cells. In contrast, CT inhibits IgA production by CH12.LX.A2 cells, a subclone of CH12.LX cells that bears only IgA. Finally, we demonstrated that CT is equally inhibitory of the proliferation of CH12.LX cells and CH12.LX.A2 cells. Taken together, these effects of CT on normal B cells and a clonal B cell line indicate that CT induces substantial numbers of mIgM+ cells to undergo isotype differentiation into mIgG+ or mIgA+ B cells. In a final series of studies we showed that the effect of CT on isotype differentiation was mimicked by the B subunit of CT, i.e., the subunit that does not activate intracellular adenylate cyclase; thus the induction of isotype differentiation by CT is not mediated by a perturbation in cAMP level.
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PMID:Cholera toxin promotes B cell isotype differentiation. 278 65

Cell surface-specific radiolabelling techniques, monoclonal antibody analyses, and chemical and physical isolation of cell fractions were used to study the surface of B. pertussis cells. Four surface specific proteins were identified by radioiodination and monoclonal antibody techniques. These included the filamentous hemagglutinin (FHA), and three outer membrane proteins-OMP91, OMP18 and OMP15. Membrane blebs were isolated from culture supernatants and shown to contain LPSII, pertussis toxin (PT), FHA, OMP91, and OMP18, but not OMP15. The level of LPS I in blebs appeared to be reduced from the level in cell envelopes. Bleb fractions contained enzymatically active adenylate cyclase (AC), and biologically active dermonecrotic toxin (DNT) and PT. Blebs were also toxic for mice, even when heated to 80 degrees C for 30 minutes. To explain these data, we propose that membrane blebs comprise an effective toxin delivery system, and that the cell surface of B. pertussis is composed of at least two domains.
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PMID:Cell surface antigens of Bordetella pertussis. 287 98

Anandamide (arachidonylethanolamide), isolated from the porcine brain, and 2-arachidonyl-glycerol (2-Ara-Gl), derived from the canine gut, are two recently identified putative endogenous cannabinoid receptor ligands. Both ligands have been reported to possess binding affinity for cannabinoid receptor subtypes, CB1 and CB2. The objective of the present studies was to investigate the immunomodulatory effects of both of these ligands in B6C3F1 mouse splenocytes. 2-Ara-Gl produced a marked and dose-related inhibition of the mixed lymphocyte response, anti-CD3 mAb-induced T-cell proliferation and LPS-induced B-cell proliferation, whereas having no inhibitory effect on phorbol-12-myristate-13-acetate/ionomycin-induced cell proliferation. Interestingly, the inhibitory effects by 2-Ara-Gl on proliferation were at least dependent in part on cell density. At high cell density, 2-Ara-Gl enhanced lymphoproliferation whereas exhibiting marked inhibitory activity at low cell density. Similarly, in vitro primary immunoglobulin M antibody-forming cell responses which are dependent on high cell density also were found to be enhanced by 2-Ara-Gl. Conversely, anandamide exhibited no inhibitory effects on cell proliferative responses to stimulation by anti-CD3 mAb, lipopolysaccharide or phorbol-12-myristate-13-acetate/ionomycin treatment. Anandamide also showed no effect on the in vitro sheep erythrocyte antibody-forming cell response. Although shown previously to markedly inhibit forskolin-stimulated cyclic AMP accumulation, 2-Ara-Gl exhibited no effect on basal adenylate cyclase activity in splenocytes. Additionally, anandamide showed negligible inhibitory effects at extremely high concentrations on forskolin-stimulated adenylate cyclase activity and no effect on basal adenylate cyclase activity in splenocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of putative cannabinoid receptor ligands, anandamide and 2-arachidonyl-glycerol, on immune function in B6C3F1 mouse splenocytes. 747 35

Increased procoagulant activity of vascular endothelial cells may be an important component in the pathogenesis of intravascular coagulation associated with gram-negative bacterial diseases. Two bovine endothelial cell (BEC) lines isolated from pulmonary arteries (ENS-2 and ENT-18) were used in this study to investigate procoagulant signal transduction pathways of endotoxin (lipopolysaccharide, LPS)--stimulated BECs. The endothelial cell line ENS-2 was sensitive to LPS as demonstrated by tissue factor (TF) expression, but in contrast, the ENT-18 endothelial cell line was unusually resistant to the effects of LPS. No remarkable quantitative difference in binding of radiolabeled LPS was detected between the two endothelial cell lines. A protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate, PMA) failed to induce TF expression in either cell line at concentrations ranging from 0.05 to 1.00 microM when used as a sole stimulus for the endothelial cells. However, when PMA was used in combination with LPS, PMA enhanced the stimulatory effect of LPS on the endothelial cells. In parallel experiments, PKC inhibitors (H-7 and GF 109203X) interfered with the stimulatory effect of LPS on the cells by decreasing tissue factor expression. We also found that an activator of adenylate cyclase, forskolin, similarly inhibited LPS-induced tissue factor activity. In contrast, protein tyrosine kinase inhibitors (genistein, lavendustin A) had no inhibitory effect on LPS-induced endothelial cell tissue factor expression. Our results collectively suggest that activation of PKC is an important step in stimulation of endothelial cells by LPS, and that LPS and phorbol esters may synergize to produce an enhanced stimulatory effect. Our results also suggest participation of cAMP in controlling LPS-mediated stimulation of endothelial cells, but fail to demonstrate a role for protein tyrosine kinase activity.
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PMID:Signal transduction pathways of bacterial lipopolysaccharide-stimulated bovine vascular endothelial cells. 807 Sep 6

The objective of the present studies was to determine whether the existence of functional glucagon receptors could be established on lympoid cells. The glucagon receptor, which positively regulates adenylate cyclase, is a member of the superfamily of seven transmembrane domain G-protein coupled receptors. Previously reported specific binding with [125I]-glucagon to a variety of lymphoid and myeloid cell preparations suggests that glucagon receptors are expressed within the immune system. In the present study, Northern analysis of polyA RNA isolated from primary mouse and rat derived lymphoid tissues and lymphoid cell lines EL-4.IL-2, Jurkat E6-1, CH12LX, and BCL1-3B3 cells were probed with a 32P-labeled human hepatic glucagon receptor. Mouse spleen and thymus, rat spleen, and the B cell line, CH12LX, all possessed a single 1.5 kb fragment (BCL1-3B3, 1.4 kb) which hybridized to the glucagon receptor cDNA probe, as compared to mouse liver which exhibited a 2.8 kb fragment. EL-4.IL-2 and Jurkat E6-1 cells possessed a 3.7 kb fragment with an additional 2.75 kb band present in Jurkat E6-1 cells. Treatment of mouse splenocytes and T- and B-lymphoma cells with glucagon (0 - 100 nM) produced a dose-dependent enhancement in intracellular cAMP which was maximal at 5 min post treatment followed by a gradual decline. Direct addition of glucagon to spleen cell cultures over a broad concentration range produced no effect on either lymphoproliferation following stimulation with anti-CD3 mAb, or LPS nor on the antibody forming cell (AFC) response to sRBC. Conversely, glucagon effectively reversed the suppression of the sRBC AFC response produced by delta9-tetrahydocannabinol (delta9-THC), and partially reversed the suppression produced by 2',3'-dideoxyadenosine, both of which are potent inhibitors of adenylate cyclase. These studies confirm the expression of functional glucagon receptors on lymphoid cells.
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PMID:Expression of functional glucagon receptors on lymphoid cells. 863 21

The enhanced nitric oxide (NO) and prostaglandin (PG) generation of activated macrophages is controlled by glucocorticoid-sensitive inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), respectively. Negative feedback regulation of iNOS expression by the products of both pathways has been suggested, but their effects on COX-2 expression have not been examined. We hae investigated the effect of E- and l-series prostaglandins that activate adenylate cyclase (AC), forskolin (a direct activator of AC), and other agents that influence the cyclicAMP/cyclicGMP systems on the ability of E. coli endotoxin (lipopolysaccharide, LPS) to induce iNOS and COX-2 in the murine macrophage cell line J774. After a 2-hr pretreatment before adding endotoxin, PGE2, PGI2, forskolin, IBMX (isobutylmethylxanthine, a cyclicAMP/cyclicGMP phosphodiesterase inhibitor), 8-bromo cyclicAMP, and arachidonic acid itself all inhibited the expression of both iNOS and COX-2 (as shown by Western blotting) and reduced NO release and COX activity, whereas PGF2 alpha and 8-bromo cyclic GMP were only weakly effective. The effects of PGE2, PGI2, and forskolin were enhanced by cotreatment with IBMX. The suppression of LPS-induced iNOS induction by PGE2 was functionally significant, in that it protected against the mild cytotoxicity of the NO generated in response to endotoxin. These results provide the first direct evidence for the feedback regulatory suppression of COX-2 induction by a PG-driven cAMP-mediated process, and show that the modulation of iNOS and COX-2 induction shares common features. They also suggest that such modulation is normally held in check by high phosphodiesterase activity within these cells.
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PMID:Repression of inducible nitric oxide synthase and cyclooxygenase-2 by prostaglandin E2 and other cyclic AMP stimulants in J774 macrophages. 910

The purpose of this study was to examine whether rCGRP has effects on TNF-alpha produced by mouse resident peritoneal macrophages. Macrophages were obtained from the peritoneal exudate of male Balb/c mouse. The cells were plated on culture dishes at a density of 2.5x10(5) cells per well and allowed to adhere for 2 hr. Pretreatment with rCGRP (10 nM-1 microM) for 24 hr, the macrophages were cultured with LPS 1 microg/ml for another 24 h. The medium was harvested for measuring TNF-alpha by ELISA kits. The results showed that rCGRP had no direct effects on TNF-alpha production, but it inhibited LPS-induced TNF-alpha production in a concentration-dependent manner. When rCGRP was at a concentration of 1 microM, the LPS-induced TNF-alpha production was inhibited by 39%. The effect of rCGRP was reversed by hCGRP(8-37) (10 microM), an antagonist of CGRP1 receptor. The LPS-induced TNF-alpha production from macrophages was also inhibited by forskolin 3 microM, an activator of adenylate cyclase. Furthermore, pretreatment with H-89 1 microM or Rp-cAMPS 100 microM, the inhibitors of cAMP-dependent protein kinase, the effect of rCGRP was abolished. These data suggest that the LPS-induced TNF-alpha production is inhibited by rCGRP via activation of cAMP responses in mouse resident peritoneal macrophages.
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PMID:Inhibition of LPS-induced TNF-alpha production by calcitonin gene-related peptide (CGRP) in cultured mouse peritoneal macrophages. 936 15


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