Acetylation of spermidine and methylglyoxal bis(guanylhydrazone) in baby-hamster kidney cells (BHK-21/C13).
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ABSTRACT:
SUBMITTER: Wallace HM
PROVIDER: S-EPMC1149278 | biostudies-other | 1988 Jul
REPOSITORIES: biostudies-other
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Project description:Methylglyoxal bis(guanylhydrazone) (1,1'-[methylethanediylidine)dinitrilo]diguanidine) inhibited the growth of BHK-21/C13 cells in monolayer cultures. Accumulation of spermidine and spermine was inhibited, whereas the accumulation of putrescine was increased. The intracellular spermidine/spermine molar ratio decreased conly slightly after exposure of the cells to 20 micrometer-methylglyoxal bis(guanylhydrazone) for 1 day. Cells incubated in the presence of the drug released less polyamine into the culture medium that did control cells, the polyamine released consisting almost exclusively of spermidine, both free and as a conjugated form.
| S-EPMC1185917 | biostudies-other
Project description:Some properties of ADP-ribose transferase, and its reaction product, from BHK-21/C13 cells are described. Enzyme activity was found almost exclusively in nuclei (90%), with the remaining 10% located in the cytosolic fraction. The nuclear enzyme is chromatin-bound and requires bivalent cations, preferably Mg2+, a pH of 8.0 and a temperature of 25 degrees C for optimal activity. Chromatin preparations incorporated radioactivity from [14C]NAD+ into acid-insoluble material for about 60 min. Kinetics for substrate NAD+ utilization were not of Michaelis--Menten type; biphasic kinetics were shown from a double-reciprocal plot (1/reaction velocity against 1/[NAD+]) and from a 'Hofstee' plot (reaction velocity/[NAD+] against reaction velocity). The transferase is unstable in the absence of Mg2+ ions. It is inhibited by thymidine, nicotinamide and nicotinamide analogues, but not by ATP, which stimulates it at concentrations of 5 mM and above. The enzyme requires thiol groups for activity; it is readily inhibited by N-ethylmaleimide at 0.5 mM. The product of the reaction is stable under acid conditions at temperatures up to 25 degrees C, but it is hydrolysed by HClO4 at 70 degrees C. It is resistant to NaOH, but is cleaved from its attachment to protein with alkali into trichloroacetic acid-insoluble and -soluble components. On the basis of Cs2SO4- density-gradient analysis under denaturing conditions (gradients included urea and guanidinium hydrochloride), and analysis of the reaction product directly on hydroxyapatite, we conclude that most of the radioactive ADP-ribose residues are firmly bound to protein, presumably in covalent linkage. Hydroxyapatite-chromatographic analysis of ADP-ribose residues released from protein by alkaline digestion showed a spectrum of molecular sizes including mono-, oligo- and poly-(ADP-ribose), when chromatin was incubated initially with [14C]NAD+ for 10 min and then for a further 30 min after addition of excess non-radioactive NAD+, only about 10% of the radioactive mono-(ADP-ribose) could be 'chased' into longer-chain molecules. Hydroxyapatite analysis was also used to show that, whereas all ADP-ribose residues were released from protein with NaOH, only 50% of them were susceptible to hydroxylamine. These hydroxylamine-sensitive residues included all size classes, although mono-(ADP-ribose) predominated. Finally, there was an approximately equal distribution of ADP-ribose incorporated into HCl-soluble proteins (including the histones) and HCl-insoluble proteins (including the non-histone proteins) when chromatin was incubated with NAD+ up to 0.5 mM, but at higher NAD+ concentrations more ADP-ribose was incorporated into the HCl-soluble fraction (82% at 4.0 mM-NAD+).
| S-EPMC1162496 | biostudies-other
Project description:A comparative study of some commonly employed laboratory procedures for studying DNA synthesis in isolated nuclei was carried out. Nuclei isolated from baby-hamster kidney (BHK-21/C13) cells synthesize DNA for 30-60min at 37 degrees C in a reaction requiring uni- and bi-valent cations, ATP and all four deoxyribonucleoside 5'-triphosphates. The addition of either ribonucleotides or cytosol from S-phase cells had no effect, but DNA synthesis was stimulated by some dextrans (mol.wt. 5x10(6)). The extent of synthesis was influenced by apparently minor variations in experimental conditions. For example, DNA synthesis by nuclei in Tris/HCl, pH7.5, was only 50% of that observed in Hepes/NaOH, pH7.5; the presence of detergents Triton X-100, Triton N-101, Nonidet P-40, Brij 58 and Tween 80 in the incubation medium altered the amount of synthesis to different extents. Although most detergents inhibited synthesis, a stimulation occurred with Tween 80 (150% of controls). These effects were reversed on washing the nuclei, except that of Brij 58, which inhibited DNA synthesis by 90-95% irreversibly. Anomalous sucrose-density-gradient sedimentation behaviour of the DNA, and of precursor [(3)H]-dTTP, was observed when nuclei were lysed with solutions of sodium dodecyl sulphate/Mg(2+) or with Sarkosyl/Mg(2+), but consistent results, showing that the DNA synthesized in vitro sedimented exclusively at about 4S, were obtained when nuclei were lysed with sodium dodecyl sulphate (without Mg(2+))/EDTA, digested with proteinase K and heated at 100 degrees C with 11% (v/v) formaldehyde to prevent macromolecular association. These results, coupled with density-labelling studies with bromodeoxyuridine and CsCl-density-gradient analysis, showed that DNA synthesis in these nuclei was replicative and was restricted to a covalent extension of Okazaki pieces previously initiated in vivo. No new initiations were observed, and the DNA was not ligated into larger molecules. The cessation of DNA synthesis after about 60 min was due to the complete utilization of available primer/template DNA.
| S-EPMC1186561 | biostudies-other
Project description:The effect of methylglyoxal bis(guanylhydrazone), a substance known to inhibit putrescine-dependent S-adenosyl-l-methionine decarboxylase, on polyamine metabolism in liver and kidney was investigated. Almost complete inhibition of the incorporation of putrescine into spermidine was obtained up to 8h after administration of 80mg of methylglyoxal bis(guanylhydrazone)/kg body wt. by intraperitoneal injection. However, by 20h after administration of the inhibitor spermidine synthesis was resumed. Considerable accumulation of putrescine occurred during this period (up to 3 times control concentrations in both tissues), but there was only a slight fall in the spermidine content. These results suggest that the putrescine-activated S-adenosyl-l-methionine decarboxylase plays an essential role in spermidine biosynthesis in rat liver and kidney, and the possibility of using methylglyoxal bis(guanylhydrazone) to study the role of polyamine synthesis in growth is discussed.
| S-EPMC1177618 | biostudies-other
Project description:UnlabelledMacrophages are a target for infection with HIV and represent one of the viral reservoirs that are relatively resistant to current antiretroviral drugs. Here we demonstrate that methylglyoxal-bis-guanylhydrazone (MGBG), a polyamine analog and potent S-adenosylmethionine decarboxylase inhibitor, decreases HIV expression in monocytes and macrophages. MGBG is selectively concentrated by these cells through a mechanism consistent with active transport by the polyamine transporter. Using a macrophage-tropic reporter virus tagged with the enhanced green fluorescent protein, we demonstrate that MGBG decreases the frequency of HIV-infected cells. The effect is dose dependent and correlates with the production of HIV p24 in culture supernatants. This anti-HIV effect was further confirmed using three macrophage-tropic primary HIV isolates. Viral life cycle mapping studies show that MGBG inhibits HIV DNA integration into the cellular DNA in both monocytes and macrophages.ImportanceOur work demonstrates for the first time the selective concentration of MGBG by monocytes/macrophages, leading to the inhibition of HIV-1 expression and a reduction in proviral load within macrophage cultures. These results suggest that MGBG may be useful in adjunctive macrophage-targeted therapy for HIV infection.
| S-EPMC4645666 | biostudies-literature
Project description:Monocyte activation and polarization play essential roles in many chronic inflammatory diseases. An imbalance of M1 and M2 macrophage activation (pro-inflammatory and alternatively activated, respectively) is believed to be a key aspect in the etiology of these diseases, thus a therapeutic approach that regulates macrophage activation could be of broad clinical relevance. Methylglyoxal-bis-guanylhydrazone (MGBG), a regulator of polyamine metabolism, has recently been shown to be concentrated in monocytes and macrophages, and interfere with HIV integration into the DNA of these cells in vitro. RNA expression analysis of monocytes from HIV+ and control donors with or without MGBG treatment revealed the only gene to be consistently down regulated by MGBG to be osteopontin (OPN). The elevated expression of this pro-inflammatory cytokine and monocyte chemoattractant is associated with various chronic inflammatory diseases. We demonstrate that MGBG is a potent inhibitor of secreted OPN (sOPN) in cultured monocytes with 50% inhibition achieved at 0.1 μM of the drug. Furthermore, inhibition of OPN RNA transcription in monocyte cultures occurs at similar concentrations of the drug. During differentiation of monocytes into macrophages in vitro, monocytes express cell surface CD16 and the cells undergo limited DNA synthesis as measured by uptake of BrdU. MGBG inhibited both activities at similar doses to those regulating OPN expression. In addition, monocyte treatment with MGBG inhibited differentiation into both M1 and M2 classes of macrophages at non-toxic doses. The inhibition of differentiation and anti-OPN effects of MGBG were specific for monocytes in that differentiated macrophages were nearly resistant to MGBG activities. Thus MGBG may have potential therapeutic utility in reducing or normalizing OPN levels and regulating monocyte activation in diseases that involve chronic inflammation.
| S-EPMC5851547 | biostudies-literature
Project description:Inhibition of polyamine synthesis by alpha-difluoromethylornithine in cultured Ehrlich ascites-carcinoma cells rapidly enhanced the uptake of exogenous putrescine, spermidine and spermine from the culture medium. In tumour cells exposed to the drug for 2 days, the intracellular concentration of spermidine was decreased to less than 10% of that found in untreated cells. However, the strikingly stimulated transport system brought the concentration of spermidine to the control values in less than 2h after supplementation of the cells with micromolar concentrations of the polyamine. In the absence of polyamine deprivation, tumour cells did not accumulate extracellular polyamines to any appreciable extent. Ascites-tumour cells deprived of putrescine and spermidine likewise concentrated methylglyoxal bis(guanylhydrazone) [1,1'-[methylethanedylidine)dinitrilo]diguanidine] at a greatly enhanced rate. A previous "priming of tumour cells with difluoromethylornithine followed by an exposure of the cells to methylglyoxal bis(guanylhydrazone) resulted in a marked and rapid anti-proliferative effect.
| S-EPMC1162421 | biostudies-other
Project description:Newly synthesized (3)H-labelled DNA was extracted from baby hamster kidney cells (BHK-21/C13 cells) and was shown to possess single-stranded properties when examined by column chromatography on benzoylated naphthoylated DEAE-cellulose, hydroxyapatite and methylated albumin on kieselguhr, and by its affinity for nitrocellulose filters. Some of the newly synthesized DNA was shown to be of lower molecular weight than the bulk of the DNA when examined by alkaline sucrose-density-gradient centrifugation. The properties observed were not affected by treatment of the DNA with ribonuclease, Pronase or amylase. The effect of the size of the DNA on its observed properties was examined and is discussed. It is concluded that DNA synthesis in BHK-21/C13 cells proceeds according to the discontinuous-mechanism model in at least one of the strands.
| S-EPMC1177497 | biostudies-other
Project description:Cultures of BHK-21/C13 cells, whose growth was inhibited by deprivation of serum, were stimulated to grow by addition of serum to the culture medium. Addition of MgCl(2) to the medium, to increase the concentration of Mg(2+) ions by 15mm, 30min before addition of serum, had no effect on the stimulation of cell growth, but inhibited the accumulation of cellular spermidine, so that the spermidine/spermine molar ratio was lower in these cultures than in cultures that had received no additional cations. The increase in the activity of ornithine decarboxylase that occurs 4-5h after serum ;step-up' was substantially diminished by increasing the concentration of Mg(2+) ions, but not of Na(+) or K(+) ions, in the medium by 30mm, 30min before addition of serum, and this inhibition was maintained for at least 24h. Methylglyoxal bis(guanylhydrazone), added to serum-deprived cultures to a concentration of 20mum, 30min before addition of serum, severely inhibited the increase in cell growth. The inhibitory effects of the drug were prevented by simultaneous addition of spermidine to the medium (to 100mum), and were partly prevented by the simultaneous addition of Mg(2+) ions (to 30mm). Mg(2+) ions were particularly effective in overcoming the inhibitory effect of methylglyoxal bis(guanylhydrazone) on the synthesis of DNA. Thus although a certain lack of specificity for cations exists in BHK-21/C13 cells, in that Mg(2+) ions can be substituted for polyamines, particularly spermidine, to some extent, there are cellular processes for which the requirement for polyamines as cations is specific.
| S-EPMC1186527 | biostudies-other
Project description:BackgroundDespite effective combination antiretroviral therapy, HIV-infected individuals develop comorbidities, including cardiovascular disease, where activated macrophages play a key role. To date, few therapies target activated monocytes and macrophages.MethodsWe evaluated a novel oral form of the polyamine biosynthesis inhibitor methylglyoxal-bis-guanylhydrazone (MGBG) on cardiovascular inflammation, carotid artery intima-media thickness (cIMT), and fibrosis in a simian immunodeficiency virus infection model of AIDS. Eleven simian immunodeficiency virus-infected animals received MGBG (30 mg/kg) once daily and 8 received a placebo control both beginning at 21 days postinfection (dpi). Animals were time sacrificed at 49 days post infection (dpi), when their matched placebo controls developed AIDS (63, 70, 77, 80), or at the study end-point (84 dpi). Aorta, carotid artery, and cardiac tissues were analyzed. Quantitative analyses of macrophage populations and T lymphocytes were done and correlated with cIMT and fibrosis.ResultsMGBG treatment resulted in 2.19-fold (CD163), 1.86-fold (CD68), 2.31-fold (CD206), and 2.12-fold (MAC387) decreases in macrophages in carotid arteries and significant 2.07-fold (CD163), 1.61-fold (CD68), 1.95-fold (MAC387), and 1.62-fold (CD206) decreases in macrophages in cardiac tissues. cIMT (1.49-fold) and fibrosis (2.05-fold) also were significantly decreased with MGBG treatment. Numbers of macrophage and the degree of fibrosis in treated animals were similar to uninfected animals. A positive correlation between decreased macrophage in the carotid artery and cIMT, and cardiac macrophages and fibrosis was found.ConclusionsThese data demonstrate that directly targeting macrophages with MGBG can reduce cardiovascular inflammation, cIMT, and fibrosis. They suggest that therapies targeting macrophages with HIV could be used in conjunction with combination antiretroviral therapy.
| S-EPMC5370195 | biostudies-literature