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

---

Query: EC:4.6.1.2 (guanylate cyclase)
8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We assessed the role of cyclic nucleotides in modulating lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-alpha) generation in human peripheral blood monocytes. Exposure of monocytes to LPS (3 ng/ml) evoked a delayed, time-dependent generation of TNF-alpha that reached a maximum level 5-6 hr after LPS challenge and remained constant for up to 24 hr. This effect was concentration dependent and resulted in a 20-40-fold increase in the release of TNF-alpha that was sensitive to actinomycin D and cycloheximide. Treatment of monocytes with agents reputed to activate the cAMP/cAMP-dependent protein kinase (PKA) cascade in general inhibited LPS-induced TNF-alpha generation. Thus, the beta 2-adrenoceptor agonists albuterol and procaterol partially (approximately 40%) suppressed TNF-alpha generation in a propranolol-sensitive manner. Furthermore, 8-bromo-cAMP, cholera toxin, prostaglandin E2, and a number of drugs (i.e., rolipram (ZK 62711), denbufylline (BRL 30892), Ro 20-1724, benafentrine (AH 21-132), that inhibit the phosphodiesterase (PDE) 4 isoenzyme family abolished cytokine generation. In contrast, forskolin, inhibitors of PDE3 and PDE5, and activators of soluble and particulate guanylyl cyclase were essentially inactive. Interestingly, rolipram failed to potentiate the inhibitory effect of albuterol on LPS-induced TNF-alpha biosynthesis but, paradoxically, synergized with albuterol in the generation of cAMP and in the activation of PKA. When PGE2 was used to activate adenylyl cyclase, however, rolipram potentiated cAMP accumulation, PKA activation, and inhibition of TNF-alpha generation. In contrast, forskolin did not increase the cAMP content of monocytes in the absence or presence of rolipram. Collectively, these data suggest that LPS-induced TNF-alpha generation by human peripheral blood monocytes is due to increased transcription and subsequent translation of the TNF-alpha gene and that these effects are suppressed by a range of agents that activate the cAMP/PKA cascade. However, the failure of rolipram to potentiate the inhibitory effect of albuterol and procaterol on TNF-alpha generation suggests that beta 2-adrenoceptor agonists may affect gene expression and/or post-transcriptional regulatory processes by, at least in part, a cAMP-independent mechanism(s).
...
PMID:Suppression of lipopolysaccharide-induced tumor necrosis factor-alpha generation from human peripheral blood monocytes by inhibitors of phosphodiesterase 4: interaction with stimulants of adenylyl cyclase. 747 3

Increased nitric oxide (NO) production plays a critical role in the mammalian pulmonary vascular adaptation to extrauterine life. NO activates soluble guanylate cyclase, increasing intracellular cGMP concentrations, thereby inducing relaxation of vascular smooth muscle. cGMP is inactivated by cyclic nucleotide phosphodiesterases (PDEs). One PDE isozyme, PDE5, specifically hydrolyzes cGMP, is abundant in lung tissues, and modifies the pulmonary vasodilatory response to exogenous NO. To investigate the regulation of PDE5 gene expression during pulmonary development, PDE5 mRNA levels, as well as cGMP-metabolizing PDE enzyme activity, were measured in the lungs of perinatal and adult rats. RNA blot hybridization revealed that PDE5 mRNA was detectable in fetal lung tissue as early as 18.5 d of the 22-d term gestation and reached maximal levels in neonatal lungs. mRNA levels in adult rat lungs were 3-4-fold less than the levels measured in lungs of 1- and 8-d-old rats. Pulmonary cGMP hydrolytic activity in 1-d-old animals was 30-fold greater than the cGMP hydrolytic activity of adult rat lungs. Zaprinast, a specific PDE5 antagonist, inhibited 52 and 56% of cGMP hydrolytic activity in lungs of 1- and 8-d-old rats, respectively, but only 18% of the activity in adult lungs. In situ hybridization revealed that PDE5 mRNA transcripts were present in the vascular smooth muscle cells of neonatal and adult lungs. PDE5 mRNA was also detected in the alveolar walls of neonatal rat lungs. These results demonstrate that the gene encoding PDE5 is abundantly expressed in the lungs of perinatal rats, and is available to participate in the mammalian pulmonary vascular transition to extrauterine life. Extravascular PDE5 gene expression in neonatal lungs suggests a potentially important nonvascular role for this enzyme during pulmonary development.
...
PMID:Cyclic-GMP-binding, cyclic-GMP-specific phosphodiesterase (PDE5) gene expression is regulated during rat pulmonary development. 947 79

This study addressed the role of guanylyl cyclase (GC) and phosphodiesterase (PDE) in interleukin (IL)-1 activation of human articular chondrocytes. The GC inhibitors LY83583 and methylene blue dose-dependently inhibited IL-1-induced nitric oxide (NO) production, inducible NO synthase (iNOS) protein, and mRNA expression. These effects of GC inhibition were consistent with the rapid induction of cGMP by IL-1, which reached maximal levels after 5 min. The effects of GC inhibitors were selective as they did not reduce IL-1-induced cyclooxygenase II protein and mRNA. An inhibitor specific for soluble GC did not affect IL-1-induced NO production, and activators of soluble GC did not induce NO. However, the expression of iNOS mRNA was induced by atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP), activators of particulate GC, indicating that particulate rather than soluble guanylyl cyclases were involved in iNOS induction. The expression of iNOS mRNA and the production of NO were induced by a slowly hydrolyzable analog of cGMP, 8-bromo-cGMP, but not by nonhydrolyzable analog, dibutyryl cGMP, suggesting that PDE rather than cGMP-dependent protein kinase mediates the cGMP effects. Chondrocytes contained extensive cGMP PDE activity. This had PDE5 biochemical features and an inhibitor profile consistent with PDE5. Furthermore, the nonisoformspecific PDE inhibitor IBMX and PDE5-specific inhibitors suppressed IL-1-induced NO release and iNOS mRNA expression. PDE5 mRNA was constitutively expressed in chondrocytes. In addition to increasing PDE5 activities, IL-1 treatment reduced the sensitivity of PDE5 to several pharmacological inhibitors by up to 50-fold. In summary, inhibitors of either GC or PDE5 prevented IL-1 induction of iNOS; IL-1 increased the rates of both cGMP generation and hydrolysis; and exogenous PDE hydrolyzable cGMP analog induced iNOS and NO. These results suggest that increased cGMP metabolic flux is sufficient to induce iNOS, and GC and PDE5 activities are required for IL-1 induction of iNOS expression via increases in coupled cGMP synthesis and hydrolysis.
...
PMID:Cyclic GMP and cGMP-binding phosphodiesterase are required for interleukin-1-induced nitric oxide synthesis in human articular chondrocytes. 976 78

1. The objective of the present paper was to evaluate the relevance of neuronal balance of cyclic AMP and cyclic GMP concentration for functional regulation of nociceptor sensitivity during inflammation. 2. Injection of PGE2 (10-100 ng paw-1) evoked a dose-dependent hyperalgesic effect which was mediated via a cyclic AMP-activated protein kinase (PKA) inasmuch as hyperalgesia was blocked by the PKA inhibitor H89. 3. The PDE4 inhibitor rolipram and RP73401, but not PDE3 and PDE5 inhibitors potentiated the hyperalgesic effects of PGE2. The hyperalgesic effect of dopamine was also enhanced by rolipram. Moreover, rolipram significantly potentiated hyperalgesia induced by carrageenan, bradykinin, TNF alpha, IL-1 beta, IL-6 and IL-8. This suggests that neuronal cyclic AMP mediates the prostanoid and sympathetic components of mechanical hyperalgesia. Moreover, in the neuron cyclic AMP is mainly metabolized by PDE4. 4. To examine the role of the NO/cyclic GMP pathway in modulating mechanical hyperalgesia, we tested the effects of the soluble guanylate cyclase inhibitor, ODQ. This substance counteracts the inhibitory effects of the NO donor, SNAP, on the hyperalgesia induced by PGE2. 5. The ODQ potentiated hyperalgesia induced by carrageenan, bradykinin, TNF alpha, IL-1 beta, IL-6 and IL-8. In contrast, ODQ had no significant effect on the hyperalgesia induced by PGE2 and dopamine. This indicates that the hyperalgesic cytokines may activate soluble guanylate cyclase, which down-regulate the ability of these substances to cause hyperalgesia. This event appears not to be mediated by prostaglandin or dopamine. 6. In conclusion, the results presented in this paper confirm an association between (i) hyperalgesia and elevated levels of cyclic AMP as well as (ii) antinociception and elevated levels of cyclic GMP. The intracellular levels of cyclic AMP that enhance hyperalgesia are controlled by the PDE4 isoform and appear to result in activation of protein kinase A whereas the intracellular levels of cyclic GMP results from activation of a soluble guanylate cyclase.
...
PMID:Pharmacological modulation of secondary mediator systems--cyclic AMP and cyclic GMP--on inflammatory hyperalgesia. 1040 57

Involvement of phosphodiesterase isoenzymes (PDEs) in guanosine-3',5'-cyclic monophosphate (cGMP) hydrolysis was analyzed in aortic smooth muscle cells. Four families of PDEs were separated from pig aorta: PDE1 (calcium-calmodulin-activated), PDE3 (cGMP-inhibited), PDE4 (adenosine 3',5'-cyclic monophosphate [cAMP]-specific), and PDE5 (cGMP-specific). Within this PDE complement, PDE1 and PDE5 mostly contributed to the hydrolysis of cGMP both in the presence and absence of calcium-calmodulin. The role of these isoenzymes in cGMP degradation was analyzed in primary cultures of porcine aortic smooth muscle cells after stimulation with sodium nitroprusside (SNP) or atrial natriuretic factor (ANF). Pretreatment with 10 microM zaprinast, a concentration that selectively inhibits PDE5, did not potentiate the SNP- or ANF-induced rise of cGMP, questioning the widespread opinion that only PDE5 accounts for cGMP hydrolysis in this tissue. Further evidence came from experiments assessing the effect of zaprinast or 3-isobutyl-1-methylxanthine at concentrations inhibiting both type 1 and type 5 isoenzymes, in which this potentiation was clearly seen. Contribution of cGMP egression to the control of intracellular cGMP levels after SNP or ANF stimulation was also investigated. Shortly after guanylate cyclase activation, extracellular cGMP levels surpassed intracellular levels. However, comparison of the amounts of cGMP extruded to the extracellular medium with those degraded by PDEs leads to the conclusion that efflux is of relatively minor importance in regulating intracellular cGMP levels. In cells made tolerant to SNP, selective PDE5 inhibition synergistically increased intra- and extracellular cGMP amounts after SNP stimulation. These results indicate a previously undescribed greater relevance of PDE5 after tolerance development in aortic smooth muscle cells.
...
PMID:Contribution of phosphodiesterase isoenzymes and cyclic nucleotide efflux to the regulation of cyclic GMP levels in aortic smooth muscle cells. 1053 60

Guanosine 3',5'-cyclic monophosphate (cGMP) has been recently reported to be involved in bone formation. ATDC5 cells were used to investigate cGMP metabolism during chondrogenic differentiation. Natriuretic peptide receptor (NPR)-A and NPR-B coupled with guanylate cyclase (GC) mediate biological functions of NPs, whereas NPR-C uncoupled with GC is thought to be the clearance receptor for NPs. The amounts of NPR-A, NPR-B, and CNP transcripts were increased but the amount of NPR-C transcripts was decreased in association with the chondrogenic differentiation of ATDC5 cells. CNP, a specific ligand for NPR-B lets ATDC5 cells accumulate great amounts of cGMP, revealing NPR-B as a dominant biological receptor through differentiation. cGMP hydrolytic activities of PDE1 and PDE5 existed in ATDC5 cells, and the activity of PDE1, which is stimulated by Ca(2+) and calmodulin (CaM) was major of them. Total cGMP hydrolytic activities as well as the amounts of PDE1 and PDE5 transcripts were enhanced during chondrogenic differentiation. Therefore, cGMP production and hydrolysis, cGMP metabolism was considered to be activated in association with chondrogenic differentiation of ATDC5 cells. These observations may lead to a better understanding of cGMP in the chondrocytes where bone formation occurs.
...
PMID:Alteration of cGMP metabolism during chondrogenic differentiation of chondroprogenitor-like EC cells, ATDC5. 1059 Mar 11

Stable toxin (ST) peptides are the causative agents for a severe form of watery diarrhea. These peptides bind to a membrane-associated form of guanylyl cyclase, guanylyl cyclase C. The result is an accumulation of cyclic guanosine monophosphate (cGMP) in the intestinal cell, regulating protein kinase activity and the phosphorylation of a number of proteins involved in ion transport across the intestine. Using the human T84 colonic cell line as a model system, we show that cGMP accumulation in these cells after ST application is regulated by the activity of the cGMP-binding, cGMP-specific phosphodiesterase (PDE5). The presence of human PDE5 in this cell line was confirmed by Western blot analysis, using an antibody raised to the bovine enzyme, and by the observation that cGMP hydrolytic activity detected in T84 cell lysates was almost completely inhibited by low concentrations of zaprinast, a specific inhibitor of PDE5. An increase in activity of PDE5 was observed in T84 cell lysates on exposure to the ST peptide and prolonged exposure of T84 cells to the ST peptide led to the induction of cellular refractoriness in these cells, which was largely contributed in terms of an increased rate of degradation of cGMP in desensitized cells as a result of PDE5 activation. This activation was correlated with an increase in the affinity of the enzyme for the substrate cGMP, as well as an increased affinity for zaprinast. We provide evidence for the first time that cGMP levels in the human colonocyte are regulated by the cGMP-hydrolytic activity of PDE5 and suggest that the expression and regulation of PDE5 in the intestine could therefore be important in controlling cGMP-mediated signaling in this tissue.
...
PMID:Expression and regulation of the cGMP-binding, cGMP-specific phosphodiesterase (PDE5) in human colonic epithelial cells: role in the induction of cellular refractoriness to the heat-stable enterotoxin peptide. 1067 26

The phosphodiesterases (PDE) activity in human trabecular meshwork cells (HTM-3) was investigated in this study in order to better understand the signal transduction pathways in the conventional outflow tract of the eye. Agonists (isoproterenol or nitroprusside) were used to stimulate adenylyl cyclase and guanylyl cyclase, respectively, in the absence and presence of nonselective IBMX or PDE5 specific inhibitors E4021 (1). The subcellular distribution of cAMP and cGMP PDEs was determined directly by PDE enzyme assays using HTM-3 cells. Levels of cyclic nucleotides were measured in the same cells by radioimmunoassay (RIA). Isoproterenol alone elevated cAMP levels, and this response was enhanced by IBMX. Nitroprusside alone caused no increase in basal cGMP levels but, in the presence of E4021, nitroprusside produced significant, dose-related elevation of cGMP levels. Subcellular distribution experiments indicated that the greatest activity for PDEs resided in the supernatant fraction. In conclusion, HTM-3 cells contain PDEs that degrade both cyclic nucleotides. The PDE activities reside predominantly in the supernatant, but the PDE activity for degrading cGMP is more pronounced. Moreover, results with E4021 suggest that PDE5 activity could play a critical role in modulating cGMP-related activity in the trabecular meshwork.
...
PMID:Functional identification of phosphodiesterase activity in human trabecular meshwork cells. 1097 27

An isoquinolone derivative, methyl-2-(4-aminophenyl)-1, 2-dihydro-1-oxo-7-(2-pyridinylmethoxy)-4-(3,4, 5-trimethoxyphenyl)-3-isoquinoline carboxylate sulfate (T-1032), was found to be a novel potent inhibitor of cyclic GMP (cGMP)-binding cGMP-specific phosphodiesterase (PDE5). We investigated the inhibitory effects of T-1032 on six PDE isozymes isolated from canine tissues. T-1032 specifically inhibited the hydrolysis of cGMP by PDE5 partially purified from canine lung, at a low concentration (IC(50) = 1.0 nM, K(i) = 1.2 nM), in a competitive manner. In contrast, the IC(50) values of T-1032 for PDE1, PDE2, PDE3, and PDE4 were more than 1 microM. T-1032 also inhibited PDE6 from canine retina with an IC(50) of 28 nM, which is of the same order of magnitude as the IC(50) of sildenafil. cGMP hydrolytic activities of two alternative splice variants of canine PDE5 expressed in COS-7 cells were inhibited by this compound to a similar extent. T-1032 increased the intracellular concentration of cGMP in cultured rat vascular smooth muscle cells in the presence and absence of C-type natriuretic peptide, an activator of membrane-bound guanylate cyclase, whereas the compound did not change cyclic AMP levels. These data indicated that T-1032, which belongs to a new structural class of PDE5 inhibitors, is a potent and selective PDE5 inhibitor. This compound may be useful in pharmacological studies to examine the role of a cGMP/PDE5 pathway in tissues.
...
PMID:Characterization and effects of methyl-2- (4-aminophenyl)-1, 2-dihydro-1-oxo-7- (2-pyridinylmethoxy)-4-(3,4, 5-trimethoxyphenyl)-3-isoquinoline carboxylate sulfate (T-1032), a novel potent inhibitor of cGMP-binding cGMP-specific phosphodiesterase (PDE5). 1100 27

Although several lines of evidence have shown a role of the nitric oxide/cyclic guanosine monophosphate signaling pathway in the nociceptive mechanism, the exact role of the phosphodiesterase (PDE) 5 enzyme via the NO-cGMP pathway is not fully understood in pain response. The present study was aimed at exploring the role of the NO-cGMP pathway in nociceptive conditions in experimental animals. Peripheral nociception was assessed by acetic acid-induced chemonociception or carrageenan-induced hyperalgesia and central nociception was assessed by tail-flick and hot-plate methods. Sildenafil exhibited dose-dependent (1, 2, 5 and 10 mg/kg, i.p.) antinociception in both male and female mice against acetic acid-induced writhing. However, it did not alter the pain threshold in central nociception (5 and 10 mg/kg, i.p.). Local administration of sildenafil (50-200 microg/paw, i.pl) also attenuated carrageenan-induced hyperalgesia. In the peripheral nociceptive reaction (acetic acid-induced chemonociception), the antinociceptive effect of sildenafil (2 mg/kg, i.p.) was enhanced by co-administration of sodium nitroprusside (0.25 mg/kg), and L-arginine (50 mg/kg). Sildenafil-induced analgesia was significantly blocked by methylene blue (1 mg/kg), a guanylate cyclase inhibitor, but was not reversed by L-NAME (10 mg/kg), a nitric oxide synthase inhibitor. But a higher dose of L-NAME (20 mg/kg) significantly reversed sildenafil analgesia. Both of these agents also reversed the facilitatory effect of L-arginine (50 mg/kg) and sodium nitroprusside (0.25 mg/kg) on sildenafil analgesia. These results suggest that sildenafil-induced analgesia is mediated via the inhibition of PDE5. The results also indicate that the guanylate cyclase system is stimulated in the peripheral nociceptive reaction. In conclusion, sildenafil produces antinociception and its effect can be potentiated by sodium nitroprusside and L-arginine, probably through the activation of the NO-cyclic GMP pathway.
...
PMID:Sildenafil-induced peripheral analgesia and activation of the nitric oxide-cyclic GMP pathway. 1147 33


1 2 3 4 5 6 7 8 Next >>

---