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:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although it has been demonstrated that NO inhibits the proliferation of different cell types, the mechanisms of its anti-mitotic action are not well understood. In this work we have studied the possible interaction of NO with the epidermal growth factor receptor (EGFR), using transfected fibroblasts which overexpress the human EGFR. The NO donors S-nitroso-N-acetylpenicillamine (SNAP), 1,1-diethyl-2-hydroxy-2-nitrosohydrazine (DEA-NO) and N-{4-[1-(3-aminopropyl)-2-hydroxy-2-nitrosohydrazino]butyl}propane -1, 3-diamine (DETA-NO) inhibited DNA synthesis of fibroblasts growing in the presence of fetal calf serum, epidermal growth factor (EGF) or EGF plus insulin, as assessed by [methyl-3H]thymidine incorporation. Neither 8-bromo-cGMP nor the cGMP-phosphodiesterase inhibitor zaprinast mimicked this effect, suggesting that NO is unlikely to inhibit cell proliferation via a cGMP-dependent pathway. SNAP, DEA-NO and DETA-NO also inhibited the transphosphorylation of the EGFR and its tyrosine kinase activity toward the exogenous substrate poly-l-(Glu-Tyr), as measured in permeabilized cells using [gamma-32P]ATP as phosphate donor. In contrast, 3-[morpholinosydnonimine hydrochloride] (SIN-1), a peroxynitrite-forming compound, did not significantly inhibit either DNA synthesis or the EGFR tyrosine kinase activity. The inhibitory action of DEA-NO on the EGFR tyrosine kinase was prevented by haemoglobin, an NO scavenger, but not by superoxide dismutase, and was reversed by dithiothreitol. The binding of EGF to its receptor was unaffected by DEA-NO. The inhibitory action of DEA-NO on the EGF-dependent transphosphorylation of the receptor was also demonstrated in intact cells by immunoblot analysis using an anti-phosphotyrosine antibody. Taken together, these results suggest that NO, but not peroxynitrite, inhibits in a reversible manner the EGFR tyrosine kinase activity by S-nitrosylation of the receptor.
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PMID:Nitric oxide reversibly inhibits the epidermal growth factor receptor tyrosine kinase. 929 Nov 7

We have studied the modulation of cyclic AMP (cAMP) accumulation by the human immunodeficiency virus type 1 (HIV 1) protein Tat in microglia and astrocyte cultures obtained from neonatal rat brain. Pretreatment of microglia with recombinant Tat resulted in a dose- and time-dependent decrease of cAMP accumulation induced by subsequent exposure to isoproterenol (1 microM). The inhibitory action of 100 ng/mL Tat approached 50% after 4 h of preincubation and reached a maximum of 70% after 24 h. The Tat-induced time- and dose-dependent decrease of cAMP accumulation was observed also when microglial cultures were stimulated with the adenylyl cyclase activator forskolin (100 microM). In both cases, Tat inhibitory action was 70% reverted by a specific monoclonal anti-Tat antibody, but was not prevented either by the phosphodiesterase inhibitor 3-isobutyl-1-methyl-xantine (100 microM) or by a 16-h pretreatment of microglial cultures with the Gi protein inhibitor pertussis toxin (10 ng/mL). All these results suggested that the viral protein acts at a step of the cAMP transduction pathway other than receptors, G proteins and phosphodiesterases. The target of Tat appeared to be adenylyl cyclase, whose activity was markedly reduced (up to 60%) in membranes prepared from Tat-treated microglial cells, both in basal conditions and after stimulation with isoproterenol and forskolin. The inability of the competitive inhibitor of nitric oxide synthase N(G)-monometyl- L-arginine (20 and 200 microM) to revert Tat action on forskolin-induced cAMP accumulation, and of two potent nitric oxide donors, PAPA and DETA (0.1-2 m M), to alter forskolin-induced cAMP accumulation, excluded an involvement of nitric oxide in Tat-induced adenylyl cyclase inhibition. On the contrary, two inhibitors of nuclear factor kappaB activation, N-tosyl-( L)-phenylalanine chloromethyl ketone (10 microM) and SN50 (25 microM), markedly prevented the reduction of forskolin-evoked cAMP accumulation by Tat, suggesting a possible role for this nuclear transcriptional factor in the regulation of adenylyl cyclase by Tat in microglia. This assumption was strengthened by the ability of lipopolysaccharide (100 ng/mL, 4 h) to mimic the inhibitory effect of the viral protein. Conversely, astrocyte cAMP accumulation was unaffected by the viral protein, as tested at various concentrations and time points. Finally, Tat inhibition of microglial adenylyl cyclase was not due to non-specific cytotoxicity. As cAMP has been reported to exert a neuroprotective role in several in vivo and in vitro models of brain pathologies, and microglia is believed to mediate Tat-induced neurotoxicity, these results suggest that the ability of Tat to inhibit cAMP synthesis in microglia may contribute to neuronal degeneration and cell death associated with HIV infection.
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PMID:Human immunodeficiency virus type 1 Tat protein decreases cyclic AMP synthesis in rat microglia cultures. 1129 2

Controlled release of nitric oxide (NO*) may be useful in the treatment of a variety of vascular disorders. NO* donors of the diazeniumdiolate family with different rates of spontaneous NO* release have been synthesized. In the current study responses to seven diazeniumdiolate NO* donors (DEA/NO*, DETA/NO*, OXI/NO*, PIPERAZI/NO*, PROLI/NO*, SPER/NO*, and SULFI/NO*) were investigated in the hindquarters vascular bed of the cat. Intravenous injections of all NO* donors caused dose-dependent decreases in systemic arterial pressure and the rank order of potency was SNP > DEA/NO* > PIPERAZI/NO* > SPER/NO* > PROLI/NO* > OXI/NO*. Injections of all NO* donors into the hindlimb perfusion circuit caused dose-related decreases in hindquarters perfusion pressure that were similar to the order of potency in decreasing systemic arterial pressure. The rank order of the time required for the response to return to 50% of the maximal decrease in pressure (T(1/2)) and total duration of action of the NO* donors was SPER/NO* > PIPERAZI/NO* > DEA/NO* > OXI/NO* > DETA/NO* > PROLI/NO* > SULFI/NO*. After treatment with the NO* synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (100 mg/kg, i.v.), hindlimb vasodilator responses to the NO* donors were not significantly different, but vasodilator responses to acetylcholine were significantly reduced. After treatment with zaprinast (2 mg/kg, i.v.), a type V cyclic 3',5'-guanosine monophosphate-specific phosphodiesterase inhibitor, the duration of vasodilator responses to the NO* donors, as measured by T(1/2), was increased significantly, whereas the duration of the response to the beta2-adrenergic receptor agonist albuterol was unchanged. These data suggest that diazeniumdiolate NO* donors are endothelium-independent, directly stimulate soluble guanylate cyclase, and decrease vascular resistance by increasing cyclic 3',5'-guanosine monophosphate levels in the hindquarters vascular bed of the cat.
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PMID:Analysis of vasodilator responses to novel nitric oxide donors in the hindquarters vascular bed of the cat. 1144 95

Acute respiratory distress syndrome (ARDS) is associated with increased superoxide (O(2)(*-)) formation in the pulmonary vasculature and negation of the bioavailability of nitric oxide (NO). Since NO inhibits NADPH oxidase expression through a cyclic GMP-mediated mechanism, sildenafil, a type V phosphodiesterase inhibitor, may be therapeutically effective in ARDS through an augmentation of NO-mediated inhibition of NADPH oxidase. Therefore, the effect of sildenafil citrate and NO-donating sildenafil (NCX 911) on O(2)(*-) formation and gp91(phox) (active catalytic subunit of NADPH oxidase) expression was investigated in cultured porcine pulmonary artery endothelial cells (PAECs). PAECs were incubated with 10 nM TXA(2) analogue, 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prostaglandin F(2alpha) (U46619) (+/-sildenafil or NCX 911), for 16 h and O(2)(*-) formation measured spectrophometrically and gp91(phox) using Western blotting. The role of the NO-cGMP axis was studied using morpholinosydnonimine hydrochloride (SIN-1), the diethylamine/NO complex (DETA-NONOate), the guanylyl cyclase inhibitor, 1H-{1,2,4}oxadiazolo{4,3-a}quinoxalin-1-one (ODQ), and the protein kinase G inhibitor, 8-bromoguanosine-3',5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-Br-cGMPS). NO release was studied using a fluorescence assay and O(2)(*-)-NO interactions by measuring nitrites. After a 16-h incubation with 10 nM U46619, both NCX 911 and sildenafil elicited a concentration-dependent inhibition of O(2)(*-) formation and gp91(phox) expression, NCX 911 being more potent (IC(50); 0.26 nM) than sildenafil citrate (IC(50); 1.85 nM). These inhibitory effects were reversed by 1 microM ODQ and 10 microM Rp-8-Br-cGMPS. NCX 911 stimulated the formation of cGMP in PAECs and generated NO in a cell-free system to a greater degree than sildenafil citrate. The inhibitory effect of sildenafil was augmented by 1 muM SIN-1 and blocked partially by the eNOS inhibitor 10 microM N(5)-(1-iminoethyl)-ornithine (L-NIO). Acutely, sildenafil and NCX 911 also inhibited O(2)(*-) formation, again blocked by 1 microM ODQ. NCX 911 reacted with O(2)(*-) generated by xanthine oxidase, an effect that was inhibited by superoxide dismutase (500 U ml(-1)). Since O(2)(*-) formation plays contributory role in ARDS, both sildenafil citrate and NCX 911 may be indicated for treating ARDS through suppression of NADPH oxidase expression and therefore of O(2)(*-) formation and preservation of NO bioavailability.
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PMID:Sildenafil citrate and sildenafil nitrate (NCX 911) are potent inhibitors of superoxide formation and gp91phox expression in porcine pulmonary artery endothelial cells. 1598 Aug 72

Keloids arise from the aberrant wound healing process and nitric oxide (NO) plays an important role in the inflammation stage of wound healing. In order to better define the potential effect of NO/cGMP signal pathway in the keloid pathogenesis, the enhancing effect of exogenous NO (released from NO donor) on collagen expression in the keloid fibroblast (KF) as well as on the induction of collagen type I protein and TGF-beta1 expression in the KF were studied in this investigation. The DETA NONOate, an NO donor, was added to the KF, as the exogenous NO, to release NO in the culture medium. The expression of collagens was then determined by assaying the total soluble collagens and collagen type I in the KF. The cellular concentration of cGMP was measured by EIA in the KF. Exogenous NO was found to enhance the expression of collagens and elevate the cellular levels of cGMP. Moreover, to evaluate the effect of the elevated cellular cGMP levels on the expression of collagen and TGF-beta1, both cGMP and TGF-beta1 were measured by ELISA. The inhibitors for phosphodiesterase (PDE), such as IBMX (3-isobutyl-1-methylxanthine), Vinpocetine, EHNA, Milrinone and Zapriast, which have been reported to reduce the ability of PDE and subsequently produce an increase of cellular cGMP, induce the production of autocrine TGF-beta1 as well as the synthesis of collagen in the KF. In this investigation, the inhibition of the PDE enzyme activity was observed to enhance the effect on the collagen synthesis, and was induced by exogenous NO. Taken together, these results have suggested that the NO/cGMP pathway could positively influence the progression of keloid formation, via the TGF-beta1 expression in the KF.
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PMID:Exogenous nitric oxide stimulated collagen type I expression and TGF-beta1 production in keloid fibroblasts by a cGMP-dependent manner. 1705 28

Cyclic-3',5'-guanosine monophosphate (cGMP) mediates the intracellular signaling cascade responsible for the nitric oxide (NO) initiated relaxation of vascular smooth muscle (VSM). However, the temporal dynamics, including the regulation of cGMP turnover, are largely unknown. Here we report new mechanistic insights into the kinetics of cGMP synthesis and hydrolysis in primary VSM cells by utilizing FRET-based cGMP-indicators [A. Honda, S.R. Adams, C.L. Sawyer, V. Lev-Ram, R.Y. Tsien, W.R. Dostmann, Proc. Natl. Acad. Sci. U S A 98 (5) (2001) 2437.]. First, 2-(N,N-Diethylamino)-diazenolate 2-oxide (DEA/NO) and 2,2'-(Hydroxynitrosohydrazono)-bis-ethanimine (DETA/NO) induced NO-concentration dependent, transient cGMP responses ("peaks") irrespective of their rates of NO release. The kinetic characteristics of these cGMP peaks were governed by the concerted action of the NO-sensitive guanylyl cyclase (GC) and phosphodiesterase type V (PDE5) as shown by their respective inhibition using 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and Sildenafil. These responses occurred in the presence of moderately elevated cGMP (5-15% FRET ratio), and thus activated PKG and phosphorylated PDE5, suggesting a prominent role for GC in the maintenance and termination of cGMP peaks. Furthermore, cGMP transients could be elicited repeatedly without apparent desensitization of GC or by suppression of cGMP via long-term PDE5 activity. These results demonstrate a continuous sensitivity of the NO/cGMP signaling system, inherent to the phasic nature of smooth muscle physiology.
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PMID:Nitric oxide-evoked transient kinetics of cyclic GMP in vascular smooth muscle cells. 1720 6

In a newly characterized cultured porcine pulmonary artery (PA) preparation, 24-h treatment with the nitric oxide (NO) donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO) decreased the response to acutely applied DETA-NO compared with 24-h control (-log EC(50) 6.55 +/- 0.12 and 5.02 +/- 0.21, respectively). Treatment of PA with the cell-permeable superoxide dismutase mimetic, Mn(III) tetra(4-benzoic acid) porphyrin chloride, did not change NO responsiveness in either freshly prepared or 24-h DETA-NO-treated PA. cGMP and cAMP phosphodiesterase activities were approximately equal in PA. Twenty-four-hour DETA-NO treatment did not change either cGMP or cAMP phosphodiesterase activities. Twenty-four hours in culture had no significant effect on soluble guanylyl cyclase (sGC) subunit mRNA expression, but 24-h DETA-NO treatment significantly decreased the expression of both sGCalpha(1) and sGCbeta(1). sGCbeta(1) protein expression was 42 +/- 4 ng/mg soluble protein. Twenty-four hours in culture without and with DETA-NO reduced sGCbeta(1) protein expression (36 +/- 3 and 31 +/- 3 ng/mg soluble protein, respectively, P < 0.025). Basal tissue cGMP [(cGMP)(i)] was significantly increased, and NO-induced (cGMP)(i) was significantly decreased by 24-h DETA-NO treatment. (cGMP)(i) normalized to the amount of sGC protein expressed in PA was significantly lower in PA treated for 24 h with DETA-NO compared with both freshly isolated and 24-h cultured PA. We conclude that prolonged NO treatment induces decreased acute NO responsiveness in part by decreasing both sGC expression and sGC-specific activity.
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PMID:Reduction in soluble guanylyl cyclase-specific activity following prolonged treatment of porcine pulmonary artery with nitric oxide. 1738 83

Pulmonary fibroblast to myofibroblast conversion is a pathophysiological feature of idiopathic pulmonary fibrosis and COPD. This conversion is induced by transforming growth factor (TGF)-beta derived from epithelial cells as well as activated macrophages that have infiltrated the lung. Preventing this conversion might be a favourable therapeutic approach. Within this study we examined the activity of different members of the phosphodiesterase (PDE) family in primary human lung fibroblasts and various lung fibroblast cell lines both before and after TGF-beta induced differentiation to myofibroblasts as reflected by the expression of alpha-smooth muscle actin. We showed that the predominant PDE activities in lung fibroblasts are attributed to PDE5, PDE1 and to a smaller extent to PDE4. cyclic GMP (cGMP)-hydrolyzing activity declines by about half after differentiation to myofibroblasts in all pulmonary fibroblasts investigated, which is accompanied by a down-regulation of PDE5 protein. Lung fibroblast to myofibroblast differentiation is blocked by treatment with the PDE4 inhibitor piclamilast alone, depending on the TGF-beta concentration applied, and in combination with prostaglandin E(2) (PGE(2)) in a synergistic manner. Despite the high PDE5 activity the PDE5 inhibitor sildenafil by itself as well as in combination with brain natriuretic peptide or the nitric oxide-donor DETA-NONOate shows no inhibiting effects. However, combining sildenafil with the guanylyl cyclase (GC) activator BAY58-2667 and ODQ (which sensitizes GC for activation by BAY58-2667) suppressed TGF-beta induced differentiation. In summary, our data indicate that drugs interfering with the cyclic AMP (cAMP)-as well as with the NO-cGMP-pathway offer the therapeutic opportunity to prevent the differentiation of pulmonary fibroblasts to myofibroblasts in lung fibrosis.
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PMID:Inhibition of TGF-beta induced lung fibroblast to myofibroblast conversion by phosphodiesterase inhibiting drugs and activators of soluble guanylyl cyclase. 1765 76

Functional evidence suggests that nitric oxide (NO) signalling in the rostral ventrolateral medulla (RVLM) is cGMP-dependent and that this pathway is impaired in hypertension. We examined cGMP expression as a marker of active NO signalling in the C1 region of the RVLM, comparing adult (>18 weeks) Wistar-Kyoto (WKY, n = 4) and spontaneously hypertensive rats (SHR, n = 4). Double label immunohistochemistry for cGMP-immunoreactivity (IR) and C1 neurons [as identified by phenylethanolamine N-methyltransferase (PNMT-IR) or tyrosine hydroxylase TH-IR)], or neuronal NO synthase (nNOS) neurones, failed to reveal cGMP-IR neurons in the RVLM of either strain, despite consistent detection of cGMP-IR in the nucleus ambiguus (NA). This was unchanged in the presence of isobutylmethylxanthine (IBMX; 0.5 mM, WKY, n = 4, SHR n = 2) and in young animals (WKY, 10-weeks, n = 3). Incubation of RVLM-slices (WKY, 10-weeks, n = 9) in DETA-NO (100 mum; 10 min) or NMDA (10 muM; 2 min) did not uncover cGMP-IR. In all studies, cGMP was prominent within the vasculature. Soluble guanylate cyclase (sGC)-IR was found throughout neurones of the RVLM, but did not co-localise with PNMT, TH or nNOS-IR neurons (WKY, 10-weeks, n = 6). Results indicate that within the RVLM, cGMP is not detectable using immunohistochemistry in the basal state and cannot be elicited by phosphodiesterase inhibition, NMDA receptor stimulation or NO donor application.
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PMID:Immunohistochemical assessment of cyclic guanosine monophosphate (cGMP) and soluble guanylate cyclase (sGC) within the rostral ventrolateral medulla. 1860 39

Our previous studies demonstrate a differential expression of nitric oxide (NO) signaling components in ES cells and our recent study demonstrated an enhanced differentiation of ES cells into myocardial cells with NO donors and soluble guanylyl cyclase (sGC) activators. Since NO-cGMP pathway exhibits a diverse role in cancer, we were interested in evaluating the role of the NO-receptor sGC and other components of the pathway in regulation of the tumor cell proliferation. Our results demonstrate a differential expression of the sGC subunits, NOS-1 and PKG mRNA and protein levels in various human cancer models. In contrast to sGC alpha(1), robust levels of sGC beta(1) were observed in OVCAR-3 (ovarian) and MDA-MB-468 (breast) cancer cells which correlated well with the sGC activity and a marked increase in cGMP levels upon exposure to the combination of a NO donor and a sGC activator. NOC-18 (DETA NONOate; NO donor), BAY41-2272 (3-(4-amino-5-cyclopropylpyrimidin-2-yl)-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine); sGC activator), NOC-18+BAY41-2272, IBMX (3-isobutyl-1-methylxanthine; phosphodiesterase inhibitor) and 8-bromo-cGMP (cGMP analog) caused growth inhibition and apoptosis in various cancer cell lines. To elucidate the molecular mechanisms involved in growth inhibition, we evaluated the effect of activators/inhibitors on ERK phosphorylation. Our studies indicate that BAY41-2272 or the combination NOC-18+BAY41-2272 caused inhibition of the basal ERK1/2 phosphorylation in OVCAR-3 (high sGC activity), SK-OV-3 and SK-Br-3 (low sGC activity) cell lines and in some cases the inhibition was rescued by the sGC inhibitor ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). These studies suggest that the effects of activators/inhibitors of NO-sGC-cGMP in tumor cell proliferation is mediated by both cGMP-dependent and independent mechanisms.
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PMID:Role of soluble guanylyl cyclase-cyclic GMP signaling in tumor cell proliferation. 1994 39


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