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

Using a modified Boyden chamber assay, we have examined the effect of cyclic nucleotides on bovine aortic endothelial cell migration in vitro. Dibutyrl cyclic 3',5'-adenosine monophosphate (5 mM) inhibited endothelial cell random migration by 67% and inhibited fibronectin-induced chemotaxis by 75%. Agents which significantly stimulated adenylate cyclase activity in endothelial cell membranes were also effective inhibitors of endothelial cell migration. Timolol blocked both the isoproterenol-induced stimulation of adenylate cyclase and the ability of isoproterenol to inhibit endothelial cell migration. Caffeine and isoproterenol together had a greater inhibitory effect on endothelial cell motility than either alone. These data suggest that cAMP may modulate vascular endothelial cell migration in an inhibitory fashion.
...
PMID:Cyclic 3',5'-adenosine monophosphate modulates vascular endothelial cell migration in vitro. 303 75

The induction of luteinizing hormone (LH) receptor by follicle-stimulating hormone (FSH) in granulosa cells was compared following culture in serum-free or serum-containing medium. Incubation of primary cultures of granulosa cells in serum-free defined medium with purified FSH resulted in dramatic increases in the level of functional LH receptors. This striking enhancement of LH receptor by FSH was completely abolished by concomitant incubation with serum (rat, horse, porcine, human or calf). The serum inhibition of FSH was not readily reversible and could be evoked throughout the culture period. The synthesis of cAMP by FSH was markedly suppressed by serum, suggesting that serum component(s) are inhibiting FSH action at the level of adenylate cyclase. Such an action, however, cannot be the sole mechanism because serum also blocked LH receptor induction by cyclic AMP analogs. In defined medium, addition of insulin, transferrin, dexamethasone or fibronectin alone had no effect on basal levels of LH receptor. However, following incubation with either insulin or dexamethasone, the FSH-induced increases in LH receptor were markedly suppressed. Insulin was found to markedly inhibit FSH-stimulated cyclic AMP formation; this was not the case with dexamethasone. The present results demonstrated the complete inhibition of FSH action by serum in cultured granulosa cells and suggest that the effect is caused by a combination of direct actions of common metabolic hormones which inhibit FSH action at multiple sites. These experiments clearly indicate the obligatory role of defined medium in the hormone-dependent differentiation of the granulosa cell in culture.
...
PMID:Role of serum-free defined medium in regulation of LH receptor in cultured rat granulosa cells. 630 7

We have investigated the regulatory role of PGI2 and its stable analogs, i.e., iloprost and cicaprost, on 12(S)-HETE- and TPA-enhanced tumor cell integrin expression and adhesion. Walker 256 carcinosarcoma cells express alpha IIb beta 3 integrin receptors, which mediate their adhesion to endothelium, subendothelial matrix and fibronectin. Adhesion is enhanced by treatment with exogenous 12(S)-HETE but not 12(R)-HETE or other lipoxygenase-derived hydroxy fatty acids, as well as by TPA. Both 12(S)-HETE and TPA enhanced alpha IIb beta 3 expression on W256 cells. PGI2 iloprost and cicaprost inhibited both 12(S)-HETE- and TPA-enhanced adhesion to endothelium and subendothelial matrix as well as alpha IIb beta 3 expression on W256 cells. The mechanism responsible for the effect of PGI2 was explored. Prostacyclin treatment of W256 cells resulted in an enhanced production of cAMP in a time- and dose-dependent manner. Pre-treatment of tumor cells with increasing concentrations of adenosine resulted in a dose-dependent decrease in the PGI2 effect on TPA or 12(S)-HETE-enhanced adhesion, suggesting that the PGI2 effect is mediated through PKA. Dibutyryl cAMP also blocked the 12(S)-HETE- or TPA-enhanced adhesion, and adenosine pre-treatment did not result in an inhibition of the dibutyryl cAMP effect. Collectively, our results suggest that the cyclooxygenase metabolite PGI2 can antagonize the lipoxygenase metabolite 12(S)-HETE- and TPA-enhanced alpha IIb beta 3 expression and tumor cell adhesion via activation of adenylate cyclase and elevation of intracellular levels of cAMP.
...
PMID:Inhibition of TPA and 12(S)-HETE-stimulated tumor cell adhesion by prostacyclin and its stable analogs: rationale for their antimetastatic effects. 753 Feb 35

Human neutrophils, plated on fibronectin-precoated wells, were found to release large quantities of superoxide anion (O2-) in response to GM-CSF. O2- production was reduced by prostaglandin E2 (PGE2) and the phosphodiesterase type IV (PDE IV) inhibitor RO 20-1724. Both agents are known to increase intracellular cyclic AMP (cAMP) levels by inducing its production (PGE2) or blocking its catabolism (RO 20-1724). When added in combination, PGE2 and RO 20-1724 had a marked synergistic inhibitory effect, which was reproduced by replacing PGE2 with a direct activator of adenylate cyclase, i.e. forskolin (FK). Moreover, the neutrophil response to GM-CSF was inhibited by a membrane-permeable analogue of cAMP in a dose-dependent manner. As GM-CSF and PGE2 are known to be generated at tissue sites of inflammation, the results suggest the existence of a PGE2-dependent regulatory pathway potentially capable of controlling the neutrophil response to GM-CSF, in turn limiting the risk of local oxidative tissue injury. Moreover, owing to its susceptibility to amplification by RO 20-1724, the PGE2-dependent pathway and in particular PDE-IV may represent a pharmacological target to reduce the generation of histotoxic oxidants by GM-CSF-responding neutrophils.
...
PMID:Cyclic AMP-elevating agents down-regulate the oxidative burst induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) in adherent neutrophils. 766 97

Studies assessing mechanisms of proximal tubular cell (PTC) physiology and pathophysiology increasingly utilize cell culture systems to avoid the complexity of whole organ/whole animal experiments. However, no well-differentiated PTC line derived from adult human kidney currently exists. Therefore, the goal of this research was to establish such a line by transduction with human papilloma virus (HPV 16) E6/E7 genes. A primary PTC culture from normal adult human renal cortex was exposed to a recombinant retrovirus containing the HPV 16 E6/E7 genes, resulting in a cell line designated HK-2 (human kidney-2) which has grown continuously in serum free media for more than one year. HK-2 cell growth is epidermal growth factor dependent and the cells retain a phenotype indicative of well-differentiated PTCs (positive for alkaline phosphatase, gamma glutamyltranspeptidase, leucine aminopeptidase, acid phosphatase, cytokeratin, alpha 3 beta 1 integrin, fibronectin; negative for factor VIII-related antigen, 6.19 antigen and CALLA endopeptidase). Furthermore, HK-2 cells retain functional characteristics of proximal tubular epithelium (Na+ dependent/phlorizin sensitive sugar transport; adenylate cyclase responsiveness to parathyroid, but not to antidiuretic, hormone). The E6/E7 genes are present in the HK-2 genome, as determined by PCR. To assess its potential usefulness as a tool for studying injury and repair, HK-2 cells were exposed to a toxic concentration of H2O2 +/- iron chelation (deferoxamine) or hydroxyl radical scavenger (Na benzoate) therapy. Only the former blocked H2O2 cytotoxicity, reproducing results previously obtained with freshly isolated rat proximal tubular segments. In conclusion, an immortalized adult human PTC line has been established by transduction with HPV 16 E6/E7 genes. It appears to be well-differentiated on the basis of its histochemical, immune cytochemical, and functional characteristics, and it can reproduce experimental results obtained with freshly isolated PTCs. Thus, this new PTC line could have substantial research application.
...
PMID:HK-2: an immortalized proximal tubule epithelial cell line from normal adult human kidney. 812 21

When baby hamster kidney (BHK) cells are allowed to spread on fibronectin-coated substrata in the absence of serum and the presence of agents which elevate intracellular 3':5'-cyclic AMP (cAMP) levels they adopt an abnormal, stellated morphology. To determine whether the invasive adenylate cyclase (AC) toxin of Bordetella pertussis induced the same response, cell extracts were prepared from several B. pertussis strains. They were characterized for AC toxin production by enzymic assay and by immunoblotting with an AC-toxin-specific monoclonal antibody. Extracts of strains producing AC toxin induced elevated levels of intracellular cAMP in BHK cells and promoted a stellation response during cell spreading. Extracts prepared from strains defective in AC toxin production showed no effect. Using image analysis to quantify the morphological change, we have demonstrated that the effect of AC toxin on cell spreading is dose dependent. This technique is a rapid and sensitive assay for the invasive AC toxin.
...
PMID:A new assay for the invasive adenylate cyclase toxin of Bordetella pertussis based on its morphological effects on the fibronectin-stimulated spreading of BHK21 cells. 818 Jun 89

In common with many other animal cells in culture, BHK21, CHO and NIH-3T3 cells adopt bizarre stellate or arborized shapes when exposed, in the absence of serum, to agents which increase cytoplasmic cyclic AMP (cAMP). Dibutyryl cAMP, 3-isobutyl-1-methylxanthine, 5'-deoxy-5'-methylthioadenosine, cholera toxin and the invasive adenylate cyclase from Bordetella pertussis all induce similar shapes. Time lapse video recording of BHK21 cells spreading on fibronectin shows that stellate shapes are generated by outgrowth of neurite-like processes led by small fans of ruffling membrane. These structures stain strongly for F actin, and their outgrowth is completely inhibited by cytochalasin D. Thus if stellation is caused by microfilament depletion, this must be selective for subsets of microfilaments. We have quantified the shape changes of BHK21 cells using the parameter dispersion. They are prevented by low concentrations (1% by volume and below) of bovine sera. The inhibitory component of foetal bovine serum acts humorally, behaves as a macromolecule and is itself inhibited by suramin, but platelet-derived growth factor, insulin, vasopressin and bradykinin are inactive. The inhibitory activity of serum may be due to phospholipids, since it can be replaced by lysophosphatidic acid in the presence of serum albumin.
...
PMID:Shapes of cells spreading on fibronectin: measurement of the stellation of BHK21 cells induced by raising cyclic AMP, and of its reversal by serum and lysophosphatidic acid. 838 76

Human neutrophils, plated on fibronectin-coated polystyrene wells, were found to exhibit a prolonged production of superoxide anion (O2-) in response to tumour necrosis factor-alpha (TNF). The TNF-triggered O2- production was significantly reduced by 10 microM prostaglandin E2 (PGE2), which was ineffective at lower doses. Moreover, the O2- production was slightly reduced by the phosphodiesterase type IV (PDE IV) inhibitor RO 20-1724. When PGE2 and RO 20-1724 were added together to TNF-triggered neutrophils they caused a marked synergistic inhibition of O2- production. The action of PGE2 could be mimicked by forskolin (FK), a well-known direct activator of adenylate cyclase. These results suggest that cyclic AMP (cAMP)-elevating agents (PGE2, FK, RO 20-1724) down-regulate the capacity of adherent neutrophils to mount the respiratory burst in response to TNF. Consistent with this interpretation, PGE2 and RO 20-1724 increased the intracellular levels of cAMP displaying synergistic activity. Moreover, the membrane-permeable analogue of cAMP, dibutyryl cAMP, was found to inhibit the TNF-induced O2- production in a dose-dependent manner. As all the aforementioned cAMP-elevating agents did not affect the O2- production in response to phorbol myristate acetate, they appear to act by interfering with the assembly of the O2(-)-generating NADPH oxidase complex rather than by directly inhibiting the activity of already working oxidase complex. In conclusion, taking into account the TNF capacity to promote PGE2 formation at sites of inflammation, our observations suggest the existence of a negative PGE2-dependent feed-back, potentially capable of controlling the neutrophil response to TNF and susceptible to amplification by PDE IV-inhibiting compounds.
...
PMID:Tumour necrosis factor alpha-induced oxidative burst in neutrophils adherent to fibronectin: effects of cyclic AMP-elevating agents. 855 55

We have shown previously that a soluble factor(s) released by the myenteric plexus promotes neurite outgrowth from postnatal striatal neurons, and that this effect was abolished by tetrodotoxin. We have now investigated the possible involvement of purines in the mediation of this neuritogenic response, by examining their effect on neurite length of striatal neurons both in co-culture with myenteric plexus explants and cultured alone. Both ATP and 2-chloroadenosine partially reversed the inhibitory effect of tetrodotoxin in co-cultures with whole myenteric plexus, while the stable ATP analogue, alpha, beta-methylene ATP, had no effect, suggesting that ATP was being broken down to adenosine before exerting its action. Further support for this view was that the ATP (P2) purinoceptor antagonist suramin did not reverse the effects of ATP, while the adenosine (P1) purinoceptor antagonist 8-(p-sulphophenyl)theophylline did antagonize the effects of ATP in tetrodotoxin-treated co-cultures. Further, both 8-(p-sulphophenyl)theophylline and adenosine deaminase reduced the effect of the myenteric plexus on striatal neurons in the absence of tetrodotoxin, and the adenylate cyclase activator forskolin completely reversed the effect of tetrodotoxin in our co-culture system. The neurite outgrowth-promoting effect of 2-chloroadenosine in tetrodotoxin-treated co-cultures was not further enhanced by a combination of neuropeptides. Serotonin and GTP were without effect on striatal neurons in the presence or absence of myenteric plexus explants. In experiments without myenteric plexus, both 2-chloroadenosine and forskolin caused a slight increase in striatal neurite length; ATP and GTP were ineffective. Basic fibroblast growth factor, nerve growth factor, neurotrophin-3 or neurotrophin-4/5 had no effect on neurite outgrowth in postnatal striatal cultures after two days in vitro. When these growth factors were added in combination with 2-chloroadenosine, the observed increase in mean neurite length did not exceed that induced by 2-chloroadenosine alone. Both 2-chloroadenosine and the ganglioside mix AGF1 increased neurite elongation of striatal neurons after two days in vitro, but an inhibition of enhanced neurite outgrowth was observed when both substances were added together. Both laminin and fibronectin were not neuritogenic for postnatal striatal neurons under our culture conditions. These observations suggest that a factor other than the growth factors tested here is involved in the promotion of striatal neurite outgrowth in co-culture with myenteric plexus explants. In summary, adenosine (probably acting through the A2 subclass of the P1 purinoceptor) leads to increased striatal neurite outgrowth in co-culture with myenteric plexus and we propose that it does so either (1) by triggering the release of a neuritogenic factor, possibly from enteric glial cells, or (2) by acting synergistically with such a growth factor. Adenosine acts via P1 purinoceptors, which leads to changes in cyclic AMP, and the response to forskolin suggests that cyclic AMP is probably involved in the events leading to increased striatal neurite outgrowth.
...
PMID:Neurite outgrowth of striatal neurons in vitro: involvement of purines in the growth-promoting effect of myenteric plexus explants. 888 77

We investigated the effect of neuropeptides, which are vasoactive intestinal polypeptide (VIP), substance P, (SP), neuropeptide Y (NPY), neurokinin A (NKA), somatostatin (SOM), calcitonin gene-related peptide (CGRP), and leucine-enkephalin (L-ENK), on the invasion of murine Colon 26-L5 adenocarcinoma cells through a reconstituted basement membrane (Matrigel) using a Transwell cell culture chamber assay. VIP, SP, NPY, and L-ENK reduced invasive potential of tumor cells in a concentration-dependent manner, whereas SOM, CGRP, and NKA had no effect. Especially, VIP showed the most effective in inhibiting tumor invasion, and achieved 50% reduction at 10(-6) M. A similar effect by VIP was also observed in cell migration to fibronectin. VIP had no effect on the growth of tumor cells at the concentrations ranging from 10(-10) to 10(-6) M. The suppressed ability of the tumor cell motility by VIP (10(-6) M) was practically recovered by co-treatment with 2',5'-dideoxyadenosine, an adenylate cyclase inhibitor. These results indicate that VIP, among the neuropeptides used, could inhibit Matrigel invasion of Colon 26-L5 carcinoma cells through partial suppression of their motility, and the reduction was associated with an intracellular cAMP-mediated pathway.
...
PMID:Differential effect of intestinal neuropeptides on invasion and migration of colon carcinoma cells in vitro. 1837 31


<< Previous 1 2 3 Next >>

---