Changes in mitochondrial calcium metabolism after treating mastocytoma cells with N6,O2′-dibutyryladenosine 3′,5′ cyclic monophosphate

Comparison of Ca2+ uptake by isolated mouse liver mitochondria, and mitochondria prepared from mastocytoma cells grown with and without N6,O2'-dibutyryladenosine 3',5' cyclic monophosphate (DB cyclic AMP) and theophylline showed several differences in their capacity to take up and retain calcium. In particular mitochondria from DB cyclic AMP-treated mastocytoma cells took up more Ca2+ than mitochondria from untreated mastocytoma cells. Ca2+ uptake by mitochondria from DB cyclic AMP-treated cells was also increased in the presence of oxalate whereas oxalate did not affect Ca2+ uptake by mitochondria from untreated mastocytoma cells and it reduced Ca2+ uptake by mouse liver mitochrondria. The results suggest that inhibiting the growth of mastocytoma cells with DB cyclic AMP alters their mitochondrial Ca2+ metabolism.     

Studies on the inhibition of hepatic lipogenesis by N6,O2′-dibutyryl adenosine 3′,5′-monophosphate

Fatty acid synthesis by isolated liver cells is dependent upon the availability of lactate and pyruvate. A lag in fatty acid synthesis is explained by time being required for lactate and pyruvate to accumulate to maximum concentrations in the incubation medium. The initial rate of fatty acid synthesis is not linear with cell concentration, being disproportionately greater at higher cell concentrations because optimal lactate and pyruvate concentrations are established in the medium more rapidly. The accumulation of lactate and pyruvate is inhibited markedly by N⁶,O^2′-dibutyryl adenosine 3′,5′-monophosphate. This accounts in part for the inhibition of fatty acid synthesis caused by this cyclic nucleotide. Other sites of action are apparent, however, because exogenous lactate plus pyruvate only partially relieves the inhibition. The profile of metabolic intermediates suggests that N⁶,O^2′-dibutyryl adenosine 3′,5′-monophosphate inhibits the conversion of glycogen to pyruvate and lactate by decreasing the effectiveness of phosphofructokinase and pyruvate kinase.     

Induction of blastocladiella emersonii germination by cyclic adenosine-3′, 5′-monophosphate

The role of adenosine 3′,5′-monophosphate (cyclic AMP) in the control of Blastocladiella emersonii germination was studied. This differentiative transition may be induced by replacing K⁺, a classical inducer, by cyclic AMP or by competitive inhibitors of cyclic AMP phosphodiesterase activity. When zoospores are treated simultaneously with two inducers at non-effective concentrations, a synergistic effect is observed between cyclic AMP and either KCl or adenine. The calcium ionophore A23187 per se is not able to elicit germination, but the association of A23187 and sub-optimal concentrations of cyclic AMP is effective. These results suggest that germination may depend on a correlation between the intracellular mobilization of calcium and cyclic AMP levels.     

Role of cyclic adenosine-3′,5′-monophosphate in olfactory reception

The action of cyclic adenosine-3,5-monophosphate (3,5-AMP) and of substances modifying the rate of its breakdown (inhibitors and activators of phosphodiesterase) on the olfactory epithelium was investigated in frogs. The slow electrical response of the olfactory epithelium to stimulation by solutions of various substances was recorded. Cyclic 3,5-AMP and its dibutyryl derivative were found to excite the olfactory receptors effectively. Responses to these substances developed after an appreciably longer delay than responses to stimulation by solutions of odiferous substances. It is postulated that the depolarizing action of 3,5-AMP and dibutyryl 3,5-AMP is manifested only after they have penetrated inside the receptor cell through its membrane. Both 5-AMP and cyclic 2,3-AMP were ineffective. In the next series of experiments the integral receptor potential was recorded in response to short stimulation by the vapor of an odiferous substance. The duration of this potential was increased after treatment of the olfactory epithelium with phosphodiesterase inhibitors: methylxanthines or papaverine. Conversely, the negative wave of the integral receptor potential was shortened under the influence of the phosphodiesterase activator imidazole. Cyclic 3,5-AMP is considered to play the role of mediator in the mechanism of excitation of the olfactory receptor; during interaction between an odiferous substance and the receptor, adenyl cyclase is activated and the concentration of 3,5-AMP increases; this, in turn, causes depolarization of the receptor cell membrane.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 5, No. 4, pp. 415–422, July–August, 1973.     

Calcium,cyclic adenosine 3′, 5′-monophosphate,and the control of cell proliferation: A review

Conclusion By manipulating the rat's calcium balance, we have discovered that the calcium homeostatic system is a main regulator of cell proliferation in the bone marrow and thymus gland. Although the limits of the system's sphere of influence have yet to be completely defined, it is already known to include such diverse elements as chicken fibroblasts, liver parenchymal cells, and circulating small lymphocytes. Of even greater significance is the possibility that the ubiquitous cyclic AMP is calcium's partner and may even be the ion's intracellular agent for the control of cell proliferation. Thus, we now have a wide variety of possible explanations for diseases involving uncontrolled cell proliferation. Issued as NRCC No. 12996. Supported by a grant from the American Cancer Society.     

A Convenient Synthesis of N4,O3′, O5′-Triacetyl-2′-Ketocytidine

Abstract

A convenient synthesis of the title compound in four steps from cytidine is reported. Key transformations include differentiation of the 2′ position as N⁴,O^3′,O^5′-triacetyl-2,2′-anhydrocytidine, opening to the arabino derivative, and oxidation of the 2′ position with the Dess-Martin reagent.     

Naturally produced isocoumarins: inhibitors of calmodulinsensitive cyclic guanosine 3′,5′-monophosphate phosphodiesterase

Summary Three isocoumarins have been isolated from a strain ofStreptoverticillium sp. and all inhibit the calmodulin-sensitive cyclic guanosine 3,5-monophosphate phosphodiesterase (EC 3.1.4.17, Boehringer Mannheim). Two of the compounds, 6,8-dihydroxy-7-methoxy-3-methyl isocoumarin and 6,7,8-trihydroxy-3-methyl isocoumarin have previously been isolated fromStreptomyces. The third fermentation product, 6,8-dihydroxy-3-methyl isocoumarin, was also found as a metabolite ofCeratocystis minor, a fungal species associated with the blue stain disease of pine [2,3].     

Facile synthesis of 2′,5′-dideoxy-, 2′,3′-dideoxy- and 3′-deoxy-1,N 6-ethenoadenosine nucleosides

Facile synthetic methods of 2′,5′-dideoxy-, 2′,3′-dideoxy- and 3′-deoxy-1,N ⁶-ethenoadenosine nucleosides by either an enzymatic dideoxyribosyl transfer reaction or a simple chemical reaction were proposed. The synthetic products were isolated and purified by preparative HPLC and their structures were confirmed by¹H NMR (500 MHz) and FAB-MS including high resolution mass measurement. These modified nucleoside analogs have not been reported yet. Therefore, these modified nucleoside analogs are of potential value to be studied further for biological activity such as anticancer or antiviral.     

An Improved Preparation of Rp and Sp N6, N6, O2′ - Tri-Benzoyl-Adenosine-3′, 5′-Cyclic Phosphoranilidates

Abstract

The conversion of the benzoylated cAMP (2) to the diastereomeric mixture of the anilidates (3) was improved. Replacing the triphenylphosphine/carbon tetrachloride mixture by oxalyl chloride in the presence of a catalytic amount of DMF followed by the addition of aniline not only increased the yield from 27 to 96% but rendered much easier the separation of the diastereoisomers (3), which were formed in approximately equal amounts. This greatly improved the accessability of Rp and Sp-cAMPS (1).     

Studies of effects of cyclic adenosine 3′,5′-monophosphate in regulation of human hemopoiesis in vitro

Summary Prostaglandin E₁ (PGE₁), high concentrations of dibutyryl cyclic AMP (dbcAMP), and theophylline were strikingly inhibitory both to tritiated thymidine ([³H]TdR) incorporation into bone marrow deoxyribonucleic acid (DNA) in vitro and to granulocytic colony growth. Autoradiography revealed that lower concentrations of dbcAMP were stimulatory to red blood cell precursors. This study was supported in part by United States Public Health Service Grant AM15163, by Health Research Council of the City of New York Career Scientist Award I-683, and by a Veterans Administration Medical Investigatorship to V. H.     

Bromine-Induced Selective N-Monodemethylation of N6, N6-Dimethyl-2′,3′-O-isopropylideneadenosine

Abstract

Bromination of the title compound 1 with bromine in phosphate buffer has led to 8-bromo-N⁶, N⁶-dimethyl-2′,3′-0-isopropylidene-adenosine (2) and 2′,3′-0-isopropylidene-N⁶-methyladenosine (3). Under similar conditions, compound 2 gave 8-bromo-2′,3′-0-isopropylidene-N⁶-methyladenosine (4). The transformations 1 → 3 and 2 → 4 represent biomimetic models of in vivo N⁶-demethylation of antibiotic puromycin.     

Comparison of cytokinin activities of the base,ribonucleoside and 5′- and cyclic-3′,5′-monophosphate ribonucleotides of N6-isopentenyl-, N6-benzyl or 8-bromo-adenine

The cytokinin activities of adenosine 3′,5′-monophosphate, N⁶,O^2″-dibutyryladenosine 3′,5−'monophosphate, 8-bromoadenosine 3′,5′-monophosphate, N⁶-(Δ²-isopentenyl)adenosine 3′,5′-monophosphate, and N⁶-benzyladenosine 3′,5′-monophosphate were determined in the tobacco bioassay and compared with the activities of the corresponding non-cyclic nucleotides, nucleosides and bases of the N⁶-isopentenyl-substituted, N⁶-benzyl-substituted, 8-bromo-substituted, and unsubstituted adenine series. In each of these series the cytokinin activities in decreasing order were: bases ⪢ nucleosides ⪖ nucleotides > cyclic nucleotides. All members of the N⁶-isopentenyl- substituted and N⁶-benzyl-substituted series were highly active cytokinins, reaching maximum activity at concentrations of 1 μM or less, whereas, as expected, all members of the unmodified adenine series were inactive in the tested concentration ranges of up to 180 and 200 μM for adenosine and adenine, and 40 μM for the adenine nucleotides. Members of the 8-bromo-substituted adenine series were much weaker cytokinins than the N⁶-substituted adenine derivatives but showed activity in the same sequence starting at a concentration of about 5 μM. Thus, in the cases of 8-bromoadenosine 3′,5′-monophosphate and N⁶,O^2′-dibutyryl-adenosine 3′,5′-monophosphate, both of which have been reported to promote cell division and growth of plant tissues, the cytokinin activity is related to the 8-bromo substituent and to the N⁶-butyryl substituent, respectively, rather than to the 3′,5′-cyclic monophosphate moiety.     

Involvement of cyclic adenosine 3′,5′-monophosphate in methylation during 1-methyladenine production by starfish ovarian follicle cells

Summary

Resumption of meiosis in starfish oocytes is induced by 1-methyladenine (1-MeAde) produced by ovarian follicle cells under the influence of a gonad-stimulating substance (GSS). With respect to 1-MeAde production by follicle cells of the starfish, Asterina pectinifera, (1) the action of GSS is initiated by a receptor mediated activation of G-proteins, resulting in the activation of adenylate cyclase and cyclic AMP (cAMP) formation; (2) 1-MeAde produced under the influence of GSS is not prestored within the follicle cells but is newly synthesized from a 1-MeAde precursor; (3) AMP plays an important role in the process of methylation during 1-MeAde biosynthesis induced by GSS.     

Influence of theophylline on concentrations of cyclic 3′,5′-adenosine monophosphate and cyclic 3′,5′-guanosine monophosphate of rat brain

The influence of theophylline (2.5–100 mg/kg p.o.) on cyclic 3,5-adenosine monophosphate (cAMP) and cyclic 3,5-guanosine monophosphate (cGMP) in brain of Sprague-Dawley rats (0.5–3.0 hr after administration of theophylline) was investigated. It was found that theophylline increases cAMP and cGMP levels when administered in a dose of 25 mg/kg or higher. A significant decrease of cGMP level was observed after administration of 10 mg/kg. The results of this study suggest that the influence of theophylline on cyclic nucleotide levels of rat brain is the result of two factors: (a) inhibitory properties of theophylline on cAMP and cGMP phosphodiesterases and (b) competition of theophylline with adenosine.     

Involvement of cyclic adenosine-3′, 5′-monophosphate in chloronema differentiation in protonema cultures of Funaria hygrometrica

The role of purine and pyrimidine ribosides, nucleotides and substituted xanthines in the differentiation of chloronema filaments in suspension cultures of protonema of the moss Funaria hygrometrica Hedw. has been examined. Cyclic adenosine-3,5-monophosphate (cAMP) and mono-and dibutyryl cAMP evoked the maximum response in wild-type protonema. ADP and ATP also enhanced chloronema differentiation but were less active than cAMP; pyrimidine derivatives were completely inactive. Inhibitors of cyclic-nucleotide phosphodiesterase aminophylline, theophylline and ICI 58, 301 (3-acetamido-6-methyl-8-n-propyl-s-triazolo-(4,3a)-pyrazine)-mimicked the effect of cAMP. A leaky, chloronema-repressed mutant was isolated and in this mutant cAMP was much more active than cyclic guanosine monophosphate and ADP in enhancing chloronema differentiation. These results strongly indicate that cAMP is involved in chloronema differentiation in Funaria, and a hypothesis on growth regulation in protonema cell cultures is proposed.Abbreviations cAMP, cyclic AMP cyclic adenosine-3, 5-monophosphate - cCMP, cGMP, cIMP cyclic cytosine-, guanosine-and inosine-3, 5-monophosphates, respectively - IAA indole-3-acetic acid - ICI 58,301 3-acetamido-6-methyl-8-n-propyl-s-triazolo-(4,3a)-pyrazine     

Cellular Phosphorylation of 2′, 3′-Dideoxyadenosine-5′-monophosphate,a Key Intermediate in The Activation of the Antiviral Agent DDI,in Human Peripheral Blood Mononuclear Cells

Abstract

2′,3′-dideoxyadenosine 5-monophosphate (ddAMP), is a key intermediate in the metabolism of the antiviral agent 2′,3′-dideoxyinosine (ddI) to its active triphosphate derivative, 2′,3′-dideoxyadenosine-5′-triphosphate (ddATP). The potential role of adenylate kinase in the phosphorylation of ddAMP was studied in human peripheral blood mononuclear cells (PBMC) and a human T cell line, CEMss. Subcellular distribution, sulfhydryl inhibitor, and substrate specificity studies support the hypothesis that the mitochondrial adenylate kinase (AK2) is a major route of cellular activation of these compounds in human lymphocytes.     

Synthesis of 2′,5′-Dideoxy-adenosine-3′-monophosphate Derivatives as Allosteric Inhibitors of Adenylyl Cyclase

Abstract

The synthesis of a fluorescent and a lipophilic conjugate of 2′,5′-dideoxy-3′-AMP, an allosteric inhibitor of adenylyl cyclase, has been devised.     

The effect of glucose and manganese on adenosine-3′, 5′-monophosphate levels during growth and differentiation of Aspergillus nidulans

The role of cyclic adenosine monophosphate (cAMP) during growth and development of Aspergillus nidulans was investigated. In normal cultures the highest amount of cAMP, expressed on a dry weight basis, was found after 24 h of growth when still more than 5% glucose was present in the medium. After depletion of the medium even a slight fall in cAMP was noted. Glucose concentrations ranging from 0.5–12% resulted in a slight decrease in the amount of cAMP as measured after 24 h of growth.Cultures with manganese deficiency resulted in a low cAMP level after 24 h of growth. However, the exhaustion of glucose in the absence of manganese was connected with a sharp increase in cAMP. This indicates that manganese shortage was not a direct cause of the low cAMP level after 24 h. The amount of cAMP rose with increasing concentration of manganese in the medium until a maximum at 0.25 M. It is tempting to speculate that this rise in cAMP in the manganese deficient culture is explained by the absence of glucose, that in the control culture is derived from the breakdown of the reserve material -1,3-glucan.Addition of manganese after glucose exhaustion to a manganese deficient culture induced cleistothecium formation. However, they contained only a few ascospores indicating the importance of -1,3 glucan as a carbon and energy source for ascospore formation. The regulation of the level of cAMP by the transport of glucose into the cell or its intracellular concentration is discussed.     

Synthesis and anti-HIV-1 evaluation of phosphonates which mimic the 5′-monophosphate of 4′-branched 2′,3′-didehydro-2′,3′-dideoxy nucleosides

Synthesis of the 4′-ethynyl and 4′-cyano phosphonates 8–11, which mimic the 5′-monophosphate of 4′-branched 2′,3′-didehydro-2′,3′-dideoxy nucleosides, was investigated by employing the 3′,4′-unsaturated nucleosides (13 and 28) as the starting material. The synthesis was initiated by the electrophilic addition of NIS/(EtO)₂P(O)CH₂OH to these unsaturated nucleosides. After introduction of the 2′,3′-double bond, the 4′-hydroxylmethyl group of the resulting adducts was transformed into the ethynyl or cyano group. While the 4′-cyano phosphonates 9 and 11 were not sufficiently stable to be isolated, the 4′-ethynyl counterparts (8 and 10) were obtained as their mono-ammonium salts. The adenine derivative 8 showed almost comparable anti-HIV-1 activity to that of d4T.     

Calcium-dependent accumulation induced by carbamylcholine of guanosine 3′,5′-monophosphate in rabbit choroid plexus

An active guanylate cyclase system was detected in isolated choroid plexus of rabbits by sodium azide (6 × 10^?5 mol/l) which increased cGMP levels tenfold within 15 min. Inhibition of cGMP phosphodiesterase by sodium azide was excluded. cGMP accumulation was also raised dose-dependently by carbamylcholine, a cholinergic agonist. Pretreatment of chroid plexus with atropine (10^?7 mol/l) reduced the effect of carbamylcholine (5 × 10^?5 mol/l) by 80%. Both carbamylcholine and sodium azide induced accumulation of cGMP also in the incubation medium, indicating rapid extrusion of the nucleotide from choroid plexus cells. The effect of carbamylcholine could be mimicked by the calcium ionophore A 23187. Incubation in calcium-free medium abolished cGMP accumulation by carbamylcholine and A 23187 but not by sodium azide, indicating a different mechanism of action. Sodium azide, carbamylcholine and A 23187 had no effect on cyclic AMP levels. Withdrawal of calcium led to an enhanced efflux of both cAMP and cGMP. Since a cholinergic innervation of stroma and epithelial cells has been described, we hypothesize that cGMP and calcium may be involved in cholinergic transmission regulating blood flow or transport processes of the choroid plexus.