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)

We evaluated the histological and ultrastructural localization of the potent anticoagulant protein, annexin V, at the light and electron microscopic levels, using immunohistochemistry and an immunogold method. Annexin V was found to localize to the microvillar surface of the villous syncytiotrophoblasts. Isolated villous-derived trophoblasts were then utilized to evaluate the expression of annexin 1 protein mRNA in response to syncytialization in vitro, as well as to exposure to adenylate cyclase and protein kinase C agonists. Levels of immunoreactive annexin V released into the conditioned media and associated with cell protein were assessed by ELISA while levels of annexin V mRNA were evaluated by Northern analysis. No significant change in either media or cell-associated annexin V concentrations were detected over time in culture or in response to 1.5 mM 8-bromo-cyclic-adenosine-monophosphate (8-b-cAMP) or 0.15 nM phorbol ester myristic acid (PMA). These results indicate that annexin V is ideally positioned to inhibit intervillous thrombosis and maintain the fluidity of the intervillous circulation. Moreover, the absence of trophoblast annexin V regulation by intracellular second messenger regulators suggests that this crucial placental anticoagulant factor is constitutively produced.
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PMID:The expression of the placental anticoagulant protein, annexin V, by villous trophoblasts: immunolocalization and in vitro regulation. 782 46

Thalidomide has significant immunomodulatory properties and has been used successfully in the treatment of oral ulcers and wasting in HIV patients. However, its use is limited by its poor bioavailability due to low solubility and short half life in solution, and teratogenic and neurotoxic side-effects. Recently, water-soluble analogues of thalidomide with significantly greater immunomodulatory activity and reduced side-effects have become available. We examined the effect of thalidomide and one analogue, CC-3052, on neutrophil apoptosis following culture for 20 h in vitro. Apoptosis was assessed by reduced CD16 expression and Annexin V binding using flow cytometry. Thalidomide or CC-3052 alone had no effect on neutrophil apoptosis when used at physiological levels. However, when used together with prostaglandin E2 (10-7 M), a potent adenylate cyclase activator, CC-3052 but not thalidomide (both 10-5 M) reduced apoptosis in neutrophils from normal and HIV+ donors. The reduced apoptosis could not be attributed to the ability of CC-3052 to reduce tumour necrosis factor-alpha (TNF-alpha) production, but may be due to its PDE4 inhibitor properties, as it increased [cAMP]i, and mimicked the effect of increasing [cAMP]i using dibutryl cAMP, a membrane-permeable analogue of cAMP. The results suggest a role for thalidomide analogue CC-3052 in reducing persistent activation of the TNF-alpha system in HIV without markedly impairing neutrophil viability.
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PMID:Thalidomide analogue CC-3052 reduces HIV+ neutrophil apoptosis in vitro. 1097 13

1. The clinical use of doxorubicin is limited by the development of severe cardiomyopathies linked, at least in part, to an abnormal increase in the rate of apoptotic cell death. Because cell shrinkage is considered to be a crucial step at the onset of apoptosis, the aim of the present study was to investigate whether a brief hypo-osmotic stress, which leads to an increase in cell volume, could interfere with the induction of apoptosis by doxorubicin in adult cardiomyocytes. 2. Cell volume expansion results in intracellular accumulation of cAMP, so we secondarily tested whether the protective effect of hypo-osmotic stress could be related to the cAMP pathway. Accordingly, apoptosis was induced by doxorubicin (1 micromol/L) in cardiomyocytes freshly isolated from New Zealand adult rabbit hearts. 3. Exposure to doxorubicin in an iso-osmotic medium (290 mOsmol/kg H2O) induced a rapid decrease in cell volume, as well as increases in annexin V labelling and caspase-3 activity, two biological markers of apoptosis. These effects of doxorubicin were abolished by 15 min pretreatment with hypo-osmotic stress at 220 mOsmol/kgH2O (HS 220). 4. This cytoprotective effect of HS 220 was still observed when doxorubicin was added to the medium 60 min later, but it was abolished when the pretreatment by HS 220 was associated with the protein kinase A inhibitor KT 5720 (200 nmol/L). 5. Conversely, 15 min pretreatment with either the cAMP analogue 8-bromo-cAMP (0.5 mmol/L) or the adenylate cyclase activator forskolin (10 micromol/L) inhibited apoptosis induced by doxorubicin. 6. In conclusion, these results demonstrate that: (i) apoptosis induced by doxorubicin can be counteracted by a hypo-osmotic stress in adult cardiomyocytes; and (ii) activation of the protein kinase A-dependent pathway plays a major role in the mechanism leading to the cytoprotective effect induced by a hypo-osmotic stress.
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PMID:Hypo-osmotic stress inhibits doxorubicin-induced apoptosis via a protein kinase A-dependent mechanism in cardiomyocytes. 1523 31

The cytotoxic effect of adenylate cyclase (AC) toxin from Bordetella pertussis on host cells has been attributed to the production of supraphysiologic levels of cyclic AMP by the toxin. We have tested this hypothesis and show that at least two different mechanisms, cAMP accumulation/ATP depletion and oligomerization/pore formation, contribute, perhaps synergistically, to AC toxin-induced cytotoxicity. Wild-type (WT) AC toxin causes cell death associated with an increase in cAMP, a reduction in ATP, activation of caspases 3/7, and increased annexin V and TUNEL staining. In contrast, a non-acylated, enzymatically active, non-haemolytic form of AC toxin is able to increase cAMP, reduce ATP and elicit annexin V staining, but the decrease in ATP and the annexin staining are transient and there is minimal caspase activation, TUNEL staining and cell death. Mutant AC toxins defective in either enzymatic activity or the ability to deliver their enzymatic domain are able to kill J774 cells, without cAMP production, and with minimal caspase activation and TUNEL staining. Comparison of the potencies of WT toxin and those of mutants that only increase cAMP or only create transmembrane pores establishes that at least two mechanisms are contributory and that simply the production of cAMP is not enough to account for the cytotoxicity produced by AC toxin.
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PMID:Macrophage cytotoxicity produced by adenylate cyclase toxin from Bordetella pertussis: more than just making cyclic AMP! 1639 Apr 41

Extracellular adenosine reduced viability of RCR-1 rat astrocytoma cells in a dose (0.3-10mM)- and treatment time (24-72h)-dependent manner. In the apoptosis assay using propidium iodide (PI) and annexin V, treatment with adenosine (1mM) for 72h increased the population of PI-negative/annexin V-positive cells, that is related to early apoptosis, and that of PI-positive/annexin V-positive cells, that is related to late apoptosis/secondary necrosis. In addition, nuclei of cells treated with adenosine (1mM) for 72h were reactive to an antibody against single-stranded DNA. Adenosine activated caspase-3, -8 and -9, but mitochondrial membrane potentials were not affected. Adenosine-induced RCR-1 cell death was significantly inhibited by 8-CPT, an antagonist of A(1) adenosine receptors, and forskolin, an adenylate cyclase activator. SQ22536, an adenylate cyclase inhibitor, alternatively, exhibited an effect similar to adenosine. CHA, an agonist of A(1) adenosine receptors, activated caspase-3 and -9, but not caspase-8. Adenosine-induced cytotoxicity of RCR-1 cells was also significantly inhibited by dipyridamole, an inhibitor of adenosine transporter, and AMDA, an inhibitor of adenosine kinase. AICAR, an activator of AMP-activated protein kinase (AMPK), reduced RCR-1 cell viability, but synergistic effect was not obtained with co-treatment with adenosine and AICAR. AICAR activated caspase-3 and -9, but not caspase-8. An additive inhibition was found in the co-presence of 8-CPT and dipyridamole. Extracellular adenosine, thus, appears to activate caspase-9 followed by the effector caspase, caspase-3, at least via two independent pathways linked to A(1) adenosine receptor-mediated adenylate cyclase inhibition and adenosine uptake into cells/conversion to AMP/activation of AMPK, possibly regardless of mitochondrial damage, thereby leading to RCR-1 cell death, dominantly by apoptosis. Moreover, caspase-8 activation could again contribute to adenosine-induced cytotoxicity, although the underlying mechanism is currently unknown. Collectively, the results of the present study may represent a new pathway for caspase activation relevant to diverse adenosine signals in cell death.
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PMID:A(1) adenosine receptor signal and AMPK involving caspase-9/-3 activation are responsible for adenosine-induced RCR-1 astrocytoma cell death. 1646 85

The present study examined the possibility to enhance lung cancer cell cytotoxicity and apoptosis of the anticancer drug cisplatin by exposure with adenylate cyclase (AC) toxin from Bordetella pertussis. A malignant mesothelioma cell line (P31) and a small-cell lung cancer cell line (U1690) were exposed to increasing concentrations of cisplatin and AC toxin, alone or in combination. Cytotoxicity was determined by a fluorescein-based assay and apoptosis by flow cytometry quantification of annexin V binding. Caspase-3, -8, and -9 activities were measured by enzyme activity assays. The cytotoxicity of AC toxin was time and dose dependent with an LD50 value at 72 h of 3 and 7 mg/L for P31 cells and U1690 cells, respectively. Cisplatin showed a similar time- and dose-dependent cytotoxicity, which was increased in the presence of a low toxic concentration (1 mg/L) of AC toxin. Furthermore, cisplatin caused a dose-dependent increase of annexin V binding cells of both cell lines after 24-h incubation, which was also enhanced in combination with AC toxin. AC toxin (1 mg/L) increased cisplatin-induced caspase-3, -8, and -9 activities in U1690 cells. Only minor increases of caspase-8 and -9 were noted for P31 cells. The present results, together with the knowledge that bacterial toxins decrease side effects of traditional cancer treatment, suggest a possibility to use them to enhance the therapeutic effect of cancer chemotherapy with reduced clinical adverse effects.
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PMID:Adenylate cyclase toxin from Bordetella pertussis enhances cisplatin-induced apoptosis to lung cancer cells in vitro. 1655 48