scholarly journals Indirect evidence for a strict negative control of S-adenosyl-l-methionine decarboxylase by spermidine in rat hepatoma cells

1981 ◽  
Vol 196 (2) ◽  
pp. 411-422 ◽  
Author(s):  
Pierre S. Mamont ◽  
Anne-Marie Joder-Ohlenbusch ◽  
Marlyse Nussli ◽  
Jeffrey Grove
Keyword(s):  
Actinomycin D ◽  
Catalytic Properties ◽  
Indirect Evidence ◽  
Negative Control ◽  
Regulatory Control ◽  
Decarboxylase Activity ◽  
Enzyme Protein ◽  
Site Of Action ◽  
Htc Cells ◽  
Rat Hepatoma

1. Direct or indirect inhibitors of l-ornithine decarboxylase (EC 4.1.1.17), structurally related or unrelated to l-ornithine, including dl-α-difluoromethylornithine, α-methylornithine and 1,3-diaminopropane, used alone or in combination, decreased polyamine concentrations in rat hepatoma tissue culture (HTC) cells and increased S-adenosyl-l-methionine decarboxylase activity (EC 4.1.1.50). 2. Comparison of the catalytic properties of S-adenosyl-l-methionine from cells with elevated and normal activities revealed no apparent modification of the catalytic site as judged by affinity for the substrate, stimulation by di- and tri-amines and inhibition by methylglyoxal bis-(guanylhydrazone). 3. Actinomycin D and cycloheximide, and RNA and a proteinsynthesis inhibitor respectively, blocked the increase of S-adenosyl-l-methionine decarboxylase activity elicited by α-difluoromethylornithine. In polyamine-depleted cells the apparent half-life of elevated S-adenosyl-l-methionine decarboxylase activity, determined by inhibition of protein synthesis, was 2.5-fold longer than in control cells. The present results suggest that elevation of S-adenosyl-l-methionine decarboxylase activity by α-difluoromethylornithine is due to stabilization of the enzyme. 4. Restoration of the normal intracellular putrescine content, by addition of putrescine to the medium of polyamine-deficient cells, transiently increased S-adenosyl-l-methionine decarboxylase activity. Thereafter, intracellular conversion of putrescine into spermidine was accompanied by inactivation of the enzyme at a rate that was similar to that found on addition of spermidine itself. No relationship between total intracellular spermine content and S-adenosyl-l-methionine decarboxylase activity could be established. 5. Addition of 1mm-1,3-diaminopropane to polyamine-deficient cells did not cause a decrease in the activity of S-adenosyl-l-methionine decarboxylase, whereas addition of 1,5-diaminopentane (cadaverine) did. 1,3-Diamino-N-(3-aminopropyl)propane did not accumulate in cells treated with α-difluoromethylornithine and 1,3-diaminopropane, whereas addition of 1,5-diaminopentane led to the accumulation of 1,5-diamino-N-(3-aminopropyl)pentane. 1,3-Diamino-N-(3-aminopropyl)propane (10μm) was as effective as spermidine in decreasing S-adenosyl-l-methionine decarboxylase activity. Thus effectiveness of a diamine in decreasing enzyme activity is related to its capability of being converted into a closely structurally related homologue of spermidine by spermidine synthase. 6. The spermidine site of action appears to be post-translational since (a) the spermidine-induced decrease of S-adenosyl-l-methionine activity was not prevented by actinomycin D and (b) spermidine in the presence of cycloheximide led to a synergistic inactivation of the enzyme with a decay rate that progressively approached control values. Altogether these results are indirect evidence for a strict negative control of S-adenosyl-l-methionine decarboxylase by spermidine and substantiate previous findings [Mamont, Duchesne, Grove & Tardif (1978) Exp. Cell Res.115, 387–393]. Spermidine appears to act on some processes involved in denaturation and/or degradation of the enzyme protein. Putrescine appears to decrease the rate of these processes. The physiological significance of the regulatory control of S-adenosyl-l-methionine decarboxylase is discussed.

Ornithine decarboxylase in rat small intestine: stimulation with food or insulin

1976 ◽  
Vol 231 (5) ◽  
pp. 1557-1561 ◽  
Author(s):  
DV Maudsley ◽  
J Leif ◽  
Y Kobayashi
Keyword(s):  
Enzyme Activity ◽  
Small Intestine ◽  
Ornithine Decarboxylase ◽  
Diamine Oxidase ◽  
Actinomycin D ◽  
Histidine Decarboxylase ◽  
Decarboxylase Activity ◽  
Adenosylmethionine Decarboxylase ◽  
Diamine Oxidase Activity ◽  
Similarities And Differences

Ornithine decarboxylase in the small intestine of starved rats was stimulated 3- to 10-fold by refeeding or administration of insulin. A peak is observed 3-5 h following treatment after which the enzyme activity rapidly declines. The rise in ornithine decarboxylase is reduced by actinomycin D or cycloheximide. The increase in enzyme activity occurs mainly in the duodenum and jejunum with less than a twofold change being observed in the ileum. A small (twofold) increase in S-adenosylmethionine decarboxylase activity in the small intestine was observed after food, but there was no change in diamine oxidase activity. Whereas pentagastrin and metiamide administration markedly stimulated histidine decarbosylase in the gastric mucosa, no consistent effect of these agents on ornithine decarboxylase in the small intestine was observed. The similarities and differences between histidine decarboxylase and ornithine decarboxylase are discussed.

Polyamine metabolism during cardiac hypertrophy

1980 ◽  
Vol 239 (5) ◽  
pp. E372-E378 ◽  
Author(s):  
A. E. Pegg ◽  
H. Hibasami
Keyword(s):  
Cardiac Hypertrophy ◽  
Polyamine Metabolism ◽  
Decarboxylase Activity ◽  
Elevated Concentration ◽  
Enzyme Protein ◽  
Carboxylase Activity ◽  
Rapid Reduction ◽  
Spermine Synthase

Treatment with thyroxine for 7 days to produce myocardial hypertrophy led to an increase in the content of putrescine, spermidine, and spermine in the rat heart. The content of decarboxylated S-adenosylmethionine, the source of the aminopropyl groups needed for polyamine synthesis, was increased by the thyroxine treatment as were the activities of ornithine and S-adenosylmethionine decarboxylases. The enhanced S-adenosylmethionine decarboxylase activity measured in vitro was due to an increase in the amount of enzyme protein as measured by immunotitration with a specific antiserum. In vivo, decarboxylation of S-adenosylmethionine was, therefore, increased both by the increased amount of enzyme protein and by the elevated concentration of putrescine (which activates the enzyme) brought about by the enhanced ornithine carboxylase activity. Spermine synthase did not change significantly during the treatment and spermidine synthase increased only slightly. Therefore, the accumulation of polyamines was mediated predominantly via the increased availability of both putrescine and decarboxylated S-adenosylmethionine. Administration of 1,3-diamino-2-propanol led to a rapid reduction in the activity of ornithine decarboxylase in the heart, and continued exposure to this substance by its inclusion in the drinking water completely prevented the increase in concentration of putrescine and polyamines in response to thyroxine. However, cardiac hypertrophy as measured by the increase in cardiac mass was not prevented by such treatment with 1,3-diaminopropanol, showing that the increased content of polyamines was not essential for the hypertrophic response.

Pharmacology of descending control systems

1985 ◽  
Vol 308 (1136) ◽  
pp. 375-391 ◽  
Keyword(s):  
Opioid Peptides ◽  
Indirect Evidence ◽  
Good Evidence ◽  
Convincing Evidence ◽  
Nociceptive Transmission ◽  
Supraspinal Control ◽  
Site Of Action ◽  
Nociceptive Information ◽  
Nociceptive Input ◽  
Spinal Inhibition

In the cat there is no convincing evidence that a particular compound mediates a supraspinal control of spinal transmission of nociceptive information. There is good evidence that opioid peptides are released segmentally in response to nociceptive input to the spinal cord and that this acts to inhibit motoneurons and to reduce transmission of nociceptive information to supraspinal areas. In the cat there is no evidence that stimulation at supraspinal sites producing analgesia results in a spinal release of opioid peptides. In the rat evidence for the latter has been obtained but there are no data from other species. Tonically present supraspinal inhibition of spinal transmission of nociceptive information in the cat does not involve opioid peptides. Indirect evidence favours a role for 5-hydroxytryptamine and noradrenaline in supraspinal control of spinal processing of nociceptive transmission. Peripheral antagonists of 5-HT have reduced spinal inhibition from stimulation at supraspinal sites but the site of action is unknown. Progress with noradrenaline involvement has been hindered by lack of a suitable antagonist. Although the amino acids, glycine and GABA are involved in segmental inhibition of transmission of nociceptive information, no convincing evidence has indicated their involvement in supraspinal controls.

TEMPORAL CHANGES IN OVARIAN ORNITHINE DECARBOXYLASE AND CYCLIC AMP IN IMMATURE RATS STIMULATED BY EXOGENOUS OR ENDOGENOUS GONADOTROPHINS

1977 ◽  
Vol 73 (3) ◽  
pp. 463-471 ◽  
Author(s):  
D. C. JOHNSON ◽  
TATSURO SASHIDA
Keyword(s):  
Enzyme Activity ◽  
Cyclic Amp ◽  
Ornithine Decarboxylase ◽  
Actinomycin D ◽  
Control Level ◽  
Decarboxylase Activity ◽  
Immature Rats ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Pregnant Mare Serum Gonadotrophin

SUMMARY Pregnant mare serum gonadotrophin given intravenously to immature rats caused a maximal (×70) increase in ornithine decarboxylase activity (ODC) at 3 h; enzyme activity declined to about ten times the control level by 9 h and a second rise began after about 20 h. Anti-PMSG given 30 min after PMSG reduced the peak response by 70%. Actinomycin D, or cycloheximide, completely prevented an increase in ODC when given with PMSG, but only cycloheximide lowered the enzyme activity when given 18 h later. Ovine FSH plus LH also produced a peak in ODC at 3 h but the activity decreased quickly and by 9 h it was at the control level. Secretion of endogenous FSH and LH, induced by hourly injections of LH releasing hormone (LH-RH) increased ODC to the same extent as did the exogenous hormones; ODC was still higher than in the controls 4 h after the last dose of LH-RH. Increased endogenous levels of FSH and LH did not consistently raise ovarian cyclic AMP content and the increases found were much less than those obtained after injection of PMSG or FSH + LH. The results indicate that increased ODC is induced and maintained by the continual presence of gonadotrophin. The dependence of increased ODC upon increased cyclic AMP cannot be unequivocally determined because of important differences in the timing of the responses and the difficulty in determining biologically significant changes in cyclic AMP.

scholarly journals Diamine-induced inhibition of liver ornithine decarboxylase

1979 ◽  
Vol 177 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Arja Kallio ◽  
Monica Löfman ◽  
Hannu Pösö ◽  
Juhani Jänne
Keyword(s):  
Enzyme Activity ◽  
Ornithine Decarboxylase ◽  
Enzyme Inhibitor ◽  
Decarboxylase Activity ◽  
Enzyme Protein ◽  
Intracellular Degradation ◽  
Ornithine Decarboxylase Activity ◽  
Normal Rat

Re!peated injections of 1,3-diaminopropane, a potent inhibitor of mammalian ornithine decarboxylase, induced protein-synthesis-dependent formation of macromolecular inhibitors or ‘antienzymes’ [Heller, Fong & Canellakis (1976) Proc. Natl. Acad. Sci. U.S.A.73, 1858–1862] to ornithine decarboxylase in normal rat liver. Addition of the macromolecular inhibitors, produced in response to repeated injections of diaminopropane, to active ornithine decarboxylase in vitro resulted in a profound loss of the enzyme activity, which, however, could be partly recovered after passage of the enzyme–inhibitor mixture through a Sephadex G-75 columin in the presence of 0.4m-NaCl. This treatment also resulted in the appearance of free inhibitor. In contrast with the separation of the enzyme and inhibitory activity after combination in vitro, it was not possible to re-activate, by using identical conditions of molecular sieving, any inhibited ornithine decarboxylase from cytosol fractions obtained from animals injected with diaminopropane. However, the idea that injection of various diamines, also in vivo, induces acute formation of macromolecular inhibitors, which reversibly combine with the enzyme, was supported by the finding that the ornithine decarboxylase activity remaining after diaminopropane injection appeared to be more stable to increased ionic strength than the enzyme activity obtained from somatotropin-treated rats. Incubation of the inhibitory cytosol fractions with antiserum to ornithine decarboxylase did not completely abolish the inhibitory action of either the cytosolic inhibitor or the antibody. A single injection of diaminopropane produced an extremely rapid decay of liver ornithine decarboxylase activity (half-life about 12min), which was comparable with, or swifter than, that induced by cycloheximide. However, although after cycloheximide treatment the amount of immunotitrable ornithine decarboxylase decreased only slightly more slowly than the enzyme activity, diaminopropane injection did not decrease the amount of the immunoreactive protein, but, on the contrary, invariably caused a marked increase in the apparent amount of antigen, after some lag period. The diamine-induced increase in the amount of the immunoreactive enzyme protein could be totally prevented by a simultaneous injection of cycloheximide. These results are in accord with the hypothesis that various diamines may result in rapid formation of macromolecular inhibitors to ornithine decarboxylase in vivo, which, after combination with the enzyme, abolish the catalytic activity but at the same time prevent the intracellular degradation of the enzyme protein.

Dopamine causes inhibition of Na+-K+-ATPase activity in rat proximal convoluted tubule segments

1987 ◽  
Vol 252 (1) ◽  
pp. F39-F45 ◽  
Author(s):  
A. Aperia ◽  
A. Bertorello ◽  
I. Seri
Keyword(s):  
Atpase Activity ◽  
Sodium Pump ◽  
Maximal Activity ◽  
Proximal Convoluted Tubule ◽  
Decarboxylase Activity ◽  
Dependent Manner ◽  
Site Of Action ◽  
Apparent Reduction ◽  
Ly 171555 ◽  
Dose Dependent

We studied the effect of dopamine (DA) on Na+-K+-ATPase activity in proximal convoluted tubule (PCT) segments dissected from perfused rat kidneys. DA inhibited Na+-K+-ATPase activity in a dose-dependent manner. Inhibition was significant with 10(-7) M DA and maximal with 10(-4) M DA. The inhibition was reversible. Enzyme inhibition occurred in the presence of DA and a DA antagonist, metoclopramide, but not when 10(5) M of the DA1 and DA2 agonists fenoldopam mesylate and LY 171555 were added in the absence of DA. In PCT segments incubated with the DA precursor dopa, Na+-K+-ATPase activity was also inhibited. However, dopa did not inhibit the sodium pump if dopa decarboxylase activity was blocked with benserazide. These findings suggest an intracellular site of action of DA. In tubules incubated in different K concentrations, 10(-5) DA decreased the maximal activity (Vmax) and increased the Km. DA 10(-5) M caused an almost immediate swelling of PCT segments. Swelling did not occur in the presence of both DA and 10(-5) M amiloride. The DA-induced tubular swelling was probably due to inhibition of Na+-K+-ATPase-mediated Na+-transport. We conclude that in rat PCT segments, DA causes a rapid and reversible inhibition of apparent Na+-K+-ATPase activity and an apparent reduction in the affinity for K. The site of action appears to be intracellular.

Growth hormone inhibition of lipogenesis in sheep adipose tissue: requirement for gene transcription and polyamines

1994 ◽  
Vol 142 (2) ◽  
pp. 235-243 ◽  
Author(s):  
C A Borland ◽  
M C Barber ◽  
M T Travers ◽  
R G Vernon
Keyword(s):  
Growth Hormone ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Ornithine Decarboxylase ◽  
Gene Transcription ◽  
Actinomycin D ◽  
Total Activity ◽  
Decarboxylase Activity ◽  
Polyamine Biosynthesis

Abstract The chronic inhibitory effect of growth hormone (GH) on lipogenesis in sheep adipose tissue explants was investigated in an in vitro tissue culture system. In the absence of other hormones, GH caused a decrease in the rate of lipogenesis after 6 h of culture. In contrast, when lipogenesis was stimulated by the presence of insulin plus dexamethasone, GH again decreased lipogenesis but after a lag of at least 12 h. Actinomycin D, an inhibitor of gene transcription, prevented the effect of GH on lipogenesis in both the absence and presence of insulin plus dexamethasone. Actinomycin D added to tissue previously incubated for 6 h in the presence of GH alone prevented further decline in lipogenesis over the next 5 h, suggesting that transcription of a short-lived mediator protein is required for the GH effect to occur. An increase in ornithine decarboxylase activity was detected in explants exposed to GH, reaching a peak after 12 h incubation; this was prevented by actinomycin D. Methylglyoxal bis-(guanylhydrazone), an inhibitor of polyamine biosynthesis, partially alleviated the effect of GH on lipogenesis; this was reversed by addition of spermidine. However, spermidine did not reverse the effects of actinomycin D, implicating a short-lived protein in addition to ornithine decarboxylase in the action of GH. In the absence of other hormones GH had no effect on either the expressed (initial) or total activity of acetyl-CoA carboxylase, but GH prevented the increase in both expressed and total activities of the enzyme induced by insulin plus dexamethasone. Varying lipolysis and fatty acid accumulation in adipose tissue by addition of adenosine deaminase plus indomethacin or bovine serum albumin to the culture medium had no effect on lipogenesis and these agents partly alleviated GH inhibition of lipogenesis. No effect of GH was found on the amount of glycerol released by cultured tissue. GH also had no effect on fatty acid esterification. Thus the chronic inhibitory effects of GH on lipogenesis involve a protein with a very short half-life. The effect also requires polyamines but does not appear to involve changes in fatty acid concentrations in the cell. In addition GH appears to inhibit lipogenesis and to antagonise insulin-stimulation of lipogenesis by different mechanisms. Journal of Endocrinology (1994) 142, 235–243

Hormonal regulation of phosphoenolpyruvate carboxykinase gene expression is mediated through modulation of an already disrupted chromatin structure

1989 ◽  
Vol 9 (3) ◽  
pp. 1289-1297
Author(s):  
Y T Ip ◽  
D K Granner ◽  
R Chalkley
Keyword(s):  
Hormonal Regulation ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Fold Increase ◽  
Coding Region ◽  
Insulin Stimulation ◽  
Base Pairs ◽  
H4iie Cells ◽  
Broad Domain ◽  
Htc Cells ◽  
Rat Hepatoma

We used indirect end labeling to identify a series of five hypersensitive (HS) sites in the phosphoenolpyruvate carboxykinase (PEPCK) gene in H4IIE rat hepatoma cells. These sites were found at -4800 base pairs (bp) (site A), at -1300 bp (site B), over a broad domain between -400 and -30 bp (site C), at +4650 bp (site D), and at +6200 bp (site E). Sites A to D were detected only in cells capable of expressing the PEPCK gene, whereas site E was present in all of the cells examined thus far. The HS sites were present in H4IIE cells even when transcriptional activity was reduced to a minimum by treatment with insulin. Stimulation of transcription by a cyclic AMP analog to a 40-fold increase over the insulin-repressed level did not affect the main features of the HS sites. Furthermore, increased transcription did not disrupt the nucleosomal arrangement of the coding region of the gene, nor did it affect the immediate 5' region (site C), which is always nucleosome-free. In HTC cells, a rat hepatoma line that is hormonally responsive but unable to synthesize PEPCK mRNA, the four expression-specific HS sites were totally absent. Our experimental results also showed that, although there is a general correlation between lack of DNA methylation and transcriptional competence of the PEPCK gene, the role, if any, of methylation in the regulation of PEPCK gene activity is likely to be exerted at very specific sites.

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