Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effects of A02011-1, a pyrazole derivative, on the proliferation of rat vascular smooth muscle cells (VSMCs) were examined. 2. A02011-1 (1-100 microM) concentration-dependently inhibited [3H]-thymidine incorporation into DNA in rat VSMCs that were synchronized by 48 h serum depletion and then re-stimulated by addition of foetal calf serum (FCS, 10%), platelet-derived growth factor (PDGF, 10 ng ml-1), 5-hydroxytryptamine (10 microM) or ADP (10 microM). The inhibitory effect of A02011-1 was fully reversible. However, FCS-induced [3H]-thymidine incorporation into rat endothelial cells was unaffected by A02011-1. 3. The concentration of A02011-1 necessary for inhibition of the FCS-induced proliferation was similar to that necessary for adenosine 3':5'-cyclic monophosphate (cyclic AMP) formation. Adenylyl cyclase activity was increased in A02011-1-treated VSMCs, whereas cyclic AMP-specific phosphodiesterase activity was unchanged. 4. A02011-1 was equipotent with forskolin but was more potent than 8-bromo-cyclic AMP against FCS (10%)-induced proliferation. 5. The antiproliferative action of A02011-1 was mimicked by 8-bromo-cyclic AMP, a membrane-permeable cyclic AMP analogue and was antagonized by 2',5'-dideoxyadenosine, an adenylyl cyclase inhibitor and by Rp-cyclic AMPS, a competitive inhibitor of cyclic AMP-dependent protein kinase (PKA) type I and II. 3-Isobutyl-1-methylxanthine (IBMX) caused significant potentiation of the antiproliferative activity of A02011-1. However, Rp-8-bromo-cyclic GMPS and staurosporine did not affect the antiproliferative activity of A02011-1. 6. A02011-1 still inhibited the FCS-induced DNA synthesis even when added 10-18h after restimulation of the serum-starved VSMCs with 10% FCS. Flow cytometry in synchronized cells revealed an acute blockade of FCS-inducible cell cycle progression at a point in the G,/S phase in A02011-1-treated cells. The inhibition of proliferation by A0201 1-1 was shown to be independent of cell damage,as documented by several criteria of cell viability.7. These results indicate that A0201 1-1 inhibition of VSMC proliferation was mediated by cyclic AMP and was due to a delay in the progression from the G1 into S phase of the cell cycle. A02011-1 did not cause cell toxicity and may thus hold promising potential for the prevention of atherosclerosis or vascular diseases.
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PMID:Antiproliferative effects of A02011-1, an adenylyl cyclase activator, in cultured vascular smooth muscle cells of rat. 762 Jul 13

1. The aims of this study were to investigate the inhibitory effects of prostaglandin E2 (PGE2) on chemotaxis of N-formyl-methionyl-leucine-phenylalanine (FMLP)-stimulated human neutrophils, and to test the hypothesis that cyclic AMP is the second messenger involved. For this purpose, the inhibitory effect of selective EP agonists, and the modulatory effects of the adenylate cyclase inhibitor, SQ 22536, the protein kinase A (PKA) inhibitors H-89 and Rp-cAMPs, and the type IV phosphodiesterase (PDE) inhibitors, rolipram and Ro20-1724 have been examined. 2. Chemotaxis has been measured using blindwell chambers. When human neutrophils were stimulated with FMLP (100 nM), PGE2 inhibited chemotaxis in a concentration-dependent manner (0.01-10 microM), with an EC50 of 90 +/- 24.5 nM, a maximum effect ranging from 45-75% and a mean inhibition of 64.5 +/- 2.4%. 3. The EP2-receptor agonists, 11-deoxy PGE1, butaprost and AH 13205 also inhibited chemotaxis. The order of potency of these agonists was PGE2 > butaprost (EC50 = 106.4 +/- 63 nM) > 11-deoxy PGE1 (EC50 = 140.9 +/- 64.7 nM) > AH 13205 (EC50 = 1.58 +/- 0.73 microM). Correlation of the ability of EP2 agonists to increase cyclic AMP and to inhibit chemotaxis was poor (r = 0.38). 4. The IP agonist, cicaprost gave similar increases in cyclic AMP to those achieved with PGE2, yet produced 50% of the maximum inhibition of chemotaxis observed with PGE2. 5. Slight potentiation of the inhibitory effects of PGE2 after type IV PDE block was observed with rolipram (EC50 for PGE2 = 57.2 +/- 5.9; 35.2 +/- 6.8 nM) but not Ro20-1724 (EC50 for PGE2 = 216.0 +/- 59.7; 97.8 +/- 50.6 nM). Type IV PDE inhibitors are themselves potent inhibitors of chemotaxis with EC50 values of 23.0 +/- 2.3 and 73.6 +/- 10.3 nM for rolipram and Ro20-1724, respectively. 6. Inhibition of cyclic AMP production with the adenylate cyclase inhibitor SQ 22,536 (0.1 mM) failed to antagonize inhibition of chemotaxis by PGE2 (EC50s for PGE2 of 57.2 +/- 5.9 and 56.8 +/- 27.3 nM, in the absence and presence of SQ 22,536, respectively) despite a reduction in the increase in cyclic AMP induced by PGE2. 7. Inhibition of PKA with either H-89 (10 microM) or Rp cyclic AMPS (10 microM) similarly failed to antagonize inhibition of chemotaxis by PGE2; EC50 for PGE2 of 90 +/- 40 and PGE2 + H-89 60 +/- 17 nM; PGE2 216.0 +/- 58.7 and PGE2 + Rp cyclic AMP 76.9 +/- 14.7 nM. 8. Of the two PKA inhibitors tested, H-89 (10 microM) and Rp cyclic AMPS (10 microM), the more effective inhibitor of PGE2-induced inhibition of neutrophil superoxide anion generation was H-89 (EC50s for PGE2 were 0.36 +/- 0.1 and > 10 microM, respectively). We have previously shown this to be a cyclic AMP-dependent effect of PGE2. 9. Confirmation of block of PKA by H-89 was suggested by the finding that H-89 blocked inhibition of superoxide anion generation observed with the type IV PDE inhibitors rolipram and Ro20-1724; EC50s of 12.9 +/- 8.9 nM for rolipram alone and rolipram+H-89 > 1 microM; Ro20-1724 alone 59.5 +/- 28.1 nM and Ro20-1724 + H-89 > 1 microM. 10. The results suggest that inhibition of chemotaxis by PGE2 and EP2 agonists is not mediated by increased neutrophil cyclic AMP levels.
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PMID:Investigation of the inhibitory effects of PGE2 and selective EP agonists on chemotaxis of human neutrophils. 868 Jul 23

1. The effects of the non-selective phosphodiesterase (PDE) inhibitor theophylline and the selective PDE4 inhibitor rolipram on leukotriene C4 (LTC4) synthesis and chemotaxis of complement 5a (C5a)- and platelet-activating factor (PAF)-stimulated human eosinophils obtained from normal and atopic donors were investigated. 2. Eosinophils were purified from peripheral venous blood of normal and atopic subjects by an immunomagnetic procedure to a purity > 99%. Eosinophils were stimulated with PAF (0.1 microM) or C5a 0.1 microM for 15 min and LTC4 was measured by radioimmunoassay (RIA). Eosinophil chemotaxis in response to PAF and C5a was assessed with 48-well microchambers (Boyden). 3. Under these conditions substantial amounts of LTC4 (about 300-1000 pg per 10(6) cells) were only detectable in the presence of indomethacin (0.1-10 microM). To explain this finding it was hypothesized that indomethacin reversed the inhibition of LTC4 synthesis by endogenously synthesized prostaglandins, in particular prostaglandin E2 (PGE2). In fact, eosinophils release 23 pg PGE2 per 10(6) cells following PAF stimulation; this PGE2 synthesis was completely inhibited by indomethacin and readdition of PGE2 inhibited eosinophil LTC4 synthesis (IC50 = 3 nM). The following experiments were performed in the presence of 10 microM indomethacin. 4. Theophylline (IC50 approximately 50 microM) and rolipram (IC50 approximately 0.03-0.2 microM) suppressed PAF- and C5a-stimulated LTC4 synthesis. This PDE inhibitor-induced suppression of LTC4 generation is mediated by activation of protein kinase A, since it was reversed by the protein kinase A inhibitor Rp-8-Br-cyclic AMPS. In addition, exogenous arachidonic acid concentration-dependently (0.3 microM-3 microM) reversed the inhibition of LTC4 synthesis by the PDE inhibitors, indicating that theophylline and rolipram suppress the mobilization of arachidonic acid. The beta 2-adrenoceptor agonist salbutamol inhibited eosinophil LTC4 synthesis (IC50 = 0.08 microM). The combination of salbutamol with theophylline (10 microM) or rolipram (3 nM) appeared to be additive. 5. Theophylline (IC50 approximately 40 microM), rolipram (IC50 approximately 0.02 microM [C5a], approximately 0.6 microM [PAF]) and PGE2 (IC50 approximately 3 nM) inhibited C5a- and PAF-stimulated eosinophil chemotaxis. The combination of PGE2 with theophylline resulted in an additive effect. 6. Both C5a- and PAF-stimulated eosinophil chemotaxis and LTC4 generation were significantly elevated in eosinophils from atopic individuals compared to normal subjects. However, eosinophils from normal and atopic individuals were not different with respect to their total cyclic AMP-PDE and PDE4 isoenzyme activities as well as the potencies of theophylline and rolipram to suppress LTC4 generation and chemotaxis.
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PMID:Effects of theophylline and rolipram on leukotriene C4 (LTC4) synthesis and chemotaxis of human eosinophils from normal and atopic subjects. 884 38

1. CD19+ B lymphocytes were purified from the peripheral blood of normal and atopic subjects to analyse and compare the phosphodiesterase (PDE) activity profile, PDE mRNA expression and the importance of PDE activity for the regulation of B cell function. 2. The majority of cyclic AMP hydrolyzing activity of human B cells was cytosolic PDE4, followed by cytosolic PDE7-like activity; marginal PDE3 activity was found only in the particulate B cell fraction. PDE1, PDE2 and PDE5 activities were not detected. 3. By cDNA-PCR analysis mRNA of the PDE4 subtypes A, B (splice variant PDE4B2) and D were detected. In addition, a weak signal for PDE3A was found. 4. No differences in PDE activities or mRNA expression of PDE subtypes were found in B cells from either normal or atopic subjects. 5. Stimulation of B lymphocytes with the polyclonal stimulus lipopolysaccharide (LPS) induced a proliferative response in a time- and concentration-dependent manner, which was increased in the presence of interleukin-4 (IL-4). PDE4 inhibitors (rolipram, piclamilast) led to an increase in the cellular cyclic AMP concentration and to an augmentation of proliferation, whereas a PDE3 inhibitor (motapizone) was ineffective, which is in accordance with the PDE profile found. The proliferation enhancing effect of the PDE4 inhibitors was partly mimicked by the cyclic AMP analogues dibutyryl (db) cyclic AMP and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3',5'-cyclic monophosphorothioate, Sp-isomer (dcl-cBIMPS), respectively. However, at concentrations exceeding 100 microM db-cyclic AMP suppressed B lymphocyte proliferation, probably as a result of cytotoxicity. Prostaglandin E2 (PGE2, 1 microM) and forskolin (10 microM) did not affect B cell proliferation, even when given in combination with rolipram. 6. Inhibition of protein kinase A (PKA) by differentially acting selective inhibitors (KT 5720, Rp-8-Br-cyclic AMPS) decreased the proliferative response of control cells and reversed the proliferation enhancing effects of rolipram. 7. Importantly, PDE4 activity in LPS/IL-4-activated B lymphocytes decreased by about 50% compared to unstimulated control values. 8. We conclude that an increase in cyclic AMP, mediated by down-regulation of PDE4 activity, is involved in the stimulation of B cell proliferation in response to LPS/IL-4. B cell proliferation in response to a mitogenic stimulus can be further enhanced by pharmacological elevation of cyclic AMP.
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PMID:Phosphodiesterase profile of human B lymphocytes from normal and atopic donors and the effects of PDE inhibition on B cell proliferation. 955 83

The present study extends our previous finding that the endothelium-independent relaxation in porcine coronary artery rings is enhanced after short-term (20 min) exposure to a physiological concentration (1 nM) of 17beta-estradiol and demonstrates that this effect may be attributable to activation of the cyclic AMP pathway. Isometric tension was recorded in isolated rings of porcine coronary arteries. Relaxation by levcromakalim and sodium nitroprusside, but not bradykinin and calcium ionophore A23187, were significantly potentiated following 20 min treatment with 1 nM 17beta-estradiol. This enhancing effect was insensitive to the transcriptional and translational inhibitors, actinomycin D and cycloheximide respectively and absent following repeated washing of the rings prior to construction of relaxation-response curves. The potentiating actions of 1 nM 17beta-estradiol on endothelium-independent relaxation were mimicked by the cyclic AMP analogue 8-Bromo-cyclic AMP and the protein kinase A activator Sp-cyclic AMPS but not by the cyclic GMP analogue 8-Bromo-cyclic GMP. The modulatory effect of 17beta-estradiol was increased in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. The cyclic AMP-dependent protein kinase A inhibitor Rp-cyclic AMPS, but not the cyclic GMP antagonist Rp-8-Bromo-cyclic GMPS, effectively inhibited the enhancing effects 1 M 17beta-estradiol had on the relaxation responses of levcromakalim and sodium nitroprusside. These data support our earlier findings that physiologically relevant concentrations of 17beta-estradiol can acutely modify vasorelaxation in vitro. Furthermore, we report that this short-term effect of 17beta-estradiol on vasorelaxation appears to be mediated via non-genomic pathways and involves the cyclic AMP cascade.
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PMID:Enhanced relaxation of porcine coronary arteries after acute exposure to a physiological level of 17beta-estradiol involves non-genomic mechanisms and the cyclic AMP cascade. 1078 Sep 81