Ornithine decarboxylase induction in cells stimulated to proliferate differs from that in continuously dividing cells

Ornithine decarboxylase activity increases at least 4–5-fold before DNA synthesis both in synchronous cycling cells and in quiescent cells stimulated to proliferate. The purpose of our experiments was to test whether the transient peaks of ornithine decarboxylase activity in both growth situations were biochemically regulated in a similar manner. We found that the regulation of this particular enzyme activity is distinct in two ways. Firstly, the addition of 2mm-hydroxyurea will block the induction of ornithine decarboxylase in continuously dividing Chinese-hamster ovary cells, while having no effect on ornithine decarboxylase induction in stimulated quiescent cells. Hydroxyurea added after the induction occurs has no effect on the enzyme activity. The apparent half-life of the enzyme is not altered in cells treated with hydroxyurea. Hydroxyurea does not affect the enzyme directly, since incubation of cell homogenates with this drug results in no loss of measurable ornithine decarboxylase activity and hydroxyurea does not markedly alter general RNA- or protein-synthesis rates. The inactivation of ornithine decarboxylase activity by hydroxyurea does not resemble the loss of activity observed with a 90min treatment with spermidine. Thiourea, a less potent inhibitor of ribonucleoside diphosphate reductase, will also inhibit ornithine decarboxylase activity, but to a lesser extent. Secondly, the expression of ornithine decarboxylase in quiescent cells stimulated to proliferate is biphasic as these cells traverse G₁ and enter S phase, whereas only one peak of activity is apparent in synchronous cycling G₁-phase cells. The time interval between the first peak of ornithine decarboxylase activity and the onset of DNA synthesis is approx. 5h longer in non-dividing cells stimulated to proliferate than in continuously dividing cells. The results suggest that the regulation of ornithine decarboxylase activity is different in the two growth systems in that the induction of ornithine decarboxylase in continuously dividing cells occurs closer in time to DNA synthesis and is dependent on deoxyribonucleoside triphosphates.     

Regulation of the activity of ornithine decarboxylase and S-adenosylmethionine decarboxylase in mammary gland and liver of lactating rats. Effects of starvation, prolactin and insulin deficiency.

1. Starvation caused a marked decrease in the activity of ornithine decarboxylase in mammary gland, together with a lesser decrease in the activity of S-adenosylmethionine decarboxylase and a marked fall in milk production. Liver ornithine decarboxylase and S-adenosylmethionine decarboxylase activities were unaffected. 2. Refeeding for 2.5 h was without effect on ornithine decarboxylase in mammary gland, but it returned the S-adenosylmethionine decarboxylase activity in mammary gland to control values and elevated both ornithine decarboxylase and S-adenosylmethionine decarboxylase in liver. 3. Refeeding for 5 h returned the activity of ornithine decarboxylase in mammary gland to fed-state values and resulted in further increases in S-adenosylmethionine decarboxylase in mammary gland and liver and in ornithine decarboxylase in liver. 4. Prolactin deficiency in fed rats resulted in decreased milk production and decreased activity of ornithine decarboxylase in mammary gland. The increase in ornithine decarboxylase activity normally seen after refeeding starved rats for 5 h was completely blocked by prolactin deficiency. 5. In fed rats, injection of streptozotocin 2.5 h before death caused a decrease in the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase in mammary gland, which could be reversed by simultaneous injection of insulin. Insulin deficiency also prevented the increase in S-adenosylmethionine decarboxylase in liver and mammary gland normally observed after refeeding starved rats for 2.5 h.     

"Active" one-carbon generation in Saccharomyces cerevisiae.

A new mutation introducing a one-carbon requirement (e.g., formate) for the glycine-supplemented growth of a serine-glycine auxotroph (ser1) was correlated with a lack of glycine decarboxylase activity. The presence of oxalate decarboxylase activity or glyoxylate decarboxylase activity did not overcome the one-carbon requirement. Another mutation characterized by the absence of oxalate decarboxylase activity did not introduce a one-carbon requirement. The presence and physiological significance of glycine decarboxylase activity in Saccharomyces are thus inferred.     

Effects of Ca2+ ionophore A23187, 1,2-dioctanoylglycerol, and dibutyryl cAMP on the activity and expression of ornithine decarboxylase in guinea pig lymphocytes

The Ca2+ ionophore A23187 induced small increases in ornithine decarboxylase activity and ornithine decarboxylase mRNA in guinea pig lymphocytes. 1,2-Dioctanoylglycerol potentiated the A23187-induced ornithine decarboxylase activity and the accumulation of mRNA for this enzyme. Dibutyryl cAMP also potentiated the enzyme activity, but had little effect on the accumulation of mRNA. 1,2-Dioctanoylglycerol and 12-O-tetradecanoylphorbol-13-acetate potentiated ornithine decarboxylase activity that had been increased by treatment with both A23187 and dibutyryl cAMP with a consistent increase in the ornithine decarboxylase mRNA. However, dibutyryl cAMP augmented ornithine decarboxylase activity that had been increased by the combination of A23187 and 1,2-dioctanoylglycerol without affecting the ornithine decarboxylase mRNA level. These results suggest that the protein kinase C and cyclic AMP pathways are involved in the enhancement of ornithine decarboxylase activity in guinea pig lymphocytes, but that the mechanisms of the enhancement differ for each pathway, the former increasing the ornithine decarboxylase mRNA level, but not the latter.     

Stimulation of Ornithine Decarboxylase Activity in Neural Cell Culture: Potential Role of Insulin

Abstract: Age-dependent decreases in the levels of ornithine decarboxylase activity were observed in the optic lobes, cerebral hemispheres, and midbrain-diencephalon of 6–17-day-old chick embryos. In dissociated cell cultures from chick embryonic brains a similar pattern of declining ornithine decarboxylase activity with time in culture was observed. Ornithine decarboxylase activity in the dissociated brain cell cultures was stimulated by changing the culture medium. The peak stimulatory effect was shown to occur 12 h after changing the medium. Although serum-free medium stimulated ornithine decarboxylase activity slightly, the presence of serum in the medium was the primary stimulatory factor. Both fetal calf serum and heat-inactivated fetal calf serum produced dose-dependent stimulation of ornithine decarboxylase activity. Dialyzed fetal calf sera stimulated ornithine decarboxylase, but to a lower level than that produced by nondialyzed sera. Insulin (0.5–10 μg/ml) stimulated ornithine decarboxylase activity in a dose-dependent manner in serum free medium. In addition, 10² M-L-asparagine stimulated ornithine decarboxylase activity in serum-free medium.     

Modulation of ornithine decarboxylase activity and ornithine decarboxylase-antizyme complex in rat heart by hormone and putrescine treatment

Ornithine decarboxylase was present in a cryptic, complexed form in an amount approximately equivalent to that of free ornithine decarboxylase activity in adult rat heart. Addition of isoproterenol (10 mg/kg) caused a notable rise in ornithine decarboxylase activity and a simultaneous decrease in the amount of the complexed enzyme. During the period of ornithine decarboxylase decay, when cardiac putrescine content had reached high values, the level of the complex increased above that of the control. Administration of putrescine (1.5 mmol/kg, twice) or dexamethasone (4 mg/kg) produced a decrease of heart ornithine decarboxylase activity, while it did not remarkably affect the level of complexed ornithine decarboxylase, therefore raising significantly the ratio of bound to total ornithine decarboxylase. Putrescine also elicited the appearance of free antizyme, concomitantly with the disappearance of free ornithine decarboxylase activity after 3-4 h of treatment. These results indicate that a significant amount of ornithine decarboxylase occurs in an inactive form in the heart under physiological conditions and that its absolute and relative levels may vary following stimuli which affect heart ornithine decarboxylase activity.     

Hydrazine stress in the diabetic: ornithine decarboxylase activity

Streptozotocin-induced diabetes of 7 weeks duration increased male Sprague-Dawley rat kidney ornithine decarboxylase activity by 4.8-fold but did not affect the liver enzyme. Hydrazine treatment of 4 hr duration stimulated equally kidney ornithine decarboxylase activities of nondiabetic and diabetic rats. Hydrazine treatment increased liver ornithine decarboxylase activity in the nondiabetic rat but did not increase it in the diabetic rat. Since hydrazine stimulates ornithine decarboxylase activity prior to polyamine and protein syntheses, we speculate that the lack of hydrazine stimulation of ornithine decarboxylase in the diabetic liver may be related in part to the unrestrained gluconeogenesis and depressed Kreb's cycle activity: the latter being required for protein synthesis.     

Decarboxylation of arginine and ornithine by arginine decarboxylase purified from cucumber (Cucumis sativus) seedlings

A purified preparation of arginine decarboxylase fromCucumis sativus seedlings displayed ornithine decarboxylase activity as well. The two decarboxylase activities associated with the single protein responded differentially to agmatine, putrescine andPi. While agmatine was inhibitory (50 %) to arginine decarboxylase activity, ornithine decarboxylase activity was stimulated by about 3-fold by the guanido arnine. Agmatine-stimulation of ornithine decarboxylase activity was only observed at higher concentrations of the amine. Inorganic phosphate enhanced arginine decarboxylase activity (2-fold) but ornithine decarboxylase activity was largely uninfluenced. Although both arginine and ornithine decarboxylase activities were inhibited by putrescine, ornithine decarboxylase activity was profoundly curtailed even at 1 mM concentration of the diamine. The enzyme-activated irreversible inhibitor for mammalian ornithine decarboxylase,viz. α-difluoromethyl ornithine, dramatically enhanced arginine decarboxylase activity (3–4 fold), whereas ornithine decarboxylase activity was partially (50%) inhibited by this inhibitor. At substrate level concentrations, the decarboxylation of arginine was not influenced by ornithine andvice-versa. Preliminary evidence for the existence of a specific inhibitor of ornithine decarboxylase activity in the crude extracts of the plant is presented. The above results suggest that these two amino acids could be decarboxylated at two different catalytic sites on a single protein.     

Ornithine decarboxylase activity in relation to DNA synthesis in mouse interfollicular epidermis and hair follicles.

The relationship between ornithine decarboxylase (L-ornithine carboxylyase, EC 4.1.1.17) activity and DNA synthetic activity was studied in mouse epidermis. Interfollicular epidermis and hair follicles were investigated separately. It was found that, in hair follicles, the variations of DNA replicative activity, which are reflected in the cyclic growth of hair, are paralleled by corresponding changes in ornithine decarboxylase activity. In both interfollicular epidermis and hair follicles, stimulation of DNA synthetic activity by plucking of hair induced a rapid and marked increase in ornithine decarboxylase activity. The relationship of steady-state and induced ornithine decarboxylase activity to DNA synthetic activity was compared in hair follicles and interfollicular epidermis. A correlation between the activity of this enzyme and DNA replication was found thereby in each of these tissues.     

Decarboxylation of p-Tyrosine: A Potential Source of p-Tyramine in Mammalian Tissues

The question of the existence of a p-tyrosine decarboxylase pathway for the formation of p-tyramine in mammalian tissues remains unresolved. Development of a sensitive and specific assay for p-tyrosine decarboxylase has permitted demonstration of this activity in rat tissues and human kidney. Tyrosine decarboxylase was purified to electrophoretic homogeneity by pH 5.0 precipitation, ammonium sulfate precipitation, gel filtration, phenyl-Sepharose chromatography, DEAE-Sephacel chromatography, and preparative isoelectric focusing. A specific rabbit antiserum to tyrosine decarboxylase was also obtained. Purified tyrosine decarboxylase possessed a narrow pH dependency with an optimum at 8.0. Benzene and certain other organic solvents dramatically stimulated tyrosine decarboxylase activity of purified enzyme. Purified tyrosine decarboxylase activity also decarboxylated L-DOPA, 5-hydroxytryptophan, 3,4-dihydroxyphenylserine, o-tyrosine, m-tyrosine, phenylalanine, histidine, and tryptophan, which suggested that the purified enzyme was aromatic L-amino acid decarboxylase. This conclusion was supported by a constant ratio of 5-hydroxytryptophan decarboxylase to tyrosine decarboxylase throughout the purification scheme and by parallel immunoprecipitation of decarboxylase activities by the specific antityrosine decarboxylase antisera. Thus, we report that p-tyrosine is decarboxylated by aromatic L-amino acid decarboxylase and that this metabolic transformation may be an important source of p-tyramine in mammalian tissues. In conclusion, neuronal tissues that synthesize catecholamines or serotonin should now be considered capable of synthesizing p-tyramine and other biogenic amines.     

Participation of amino acid decarboxylases in biochemical interactions between triticale (Triticosecale; Poaceae) and bird cherry-oat aphid (Rhopalosiphum padi; Aphididae)

The roles of ornithine decarboxylase, lysine decarboxylase and tyrosine decarboxylase in biochemical interactions of two cultivars of winter triticale (Triticosecale), Tornado and Witon, and bird cherry-oat aphid (Rhopalosiphum padi L.) were determined. Results showed the resistant Witon had higher lysine decarboxylase activity than the susceptible Tornado. There was a significant negative correlation between the density of R. padi populations and lysine decarboxylase activity. Such correlations did not occur for the other decarboxylases. Aphid feeding induced a decrease of lysine decarboxylase activity within both cultivars after one week of infestation and increased its activity after two weeks in the moderately resistant Witon. Ornithine decarboxylase activity was induced in tissues of the susceptible Tornado and inhibited in Witon after two weeks of infestation. Aphid infestations did not change tyrosine decarboxylase activity in Witon, whereas in Tornado it decreased in activity after one day of aphid feeding and then increased after two weeks. It was concluded that of the three enzymes studied, lysine decarboxylase was the most important in the response of winter triticale to infestation by R. padi.     

Changes in antizyme-ornithine decarboxylase complexes in tissues of hormone-treated rats

The presence of antizyme-ornithine decarboxylase complex in thymus and kidney of rats was demonstrated using the method of Y Murakami et al. [(1985) Biochem. J. 225, 689-697]. A very small amount of complex was found in kidney of control rats, accounting for only 1-3% of total enzyme in the tissue, while in thymus, approximately one-third of the total ornithine decarboxylase in thymus occurred as an antizyme-enzyme complex. After treatment with dexamethasone, both free ornithine decarboxylase and antizyme-ornithine decarboxylase decreased in thymus, the free enzyme activity decreasing more rapidly. In kidney, the concentration of the antizyme-ornithine decarboxylase complex increased after dexamethasone treatment, but only after the induction of free enzyme activity had reached its peak and begun to decrease. The pattern of the changes in amount of antizyme-ornithine decarboxylase complex after prolactin treatment differed from those observed in the dexamethasone-treated animals. In both kidney and thymus, the concentration of antizyme-ornithine decarboxylase complex increased concurrently with the induction of free enzyme activity. Both free and complexed ornithine decarboxylase had increased at 2.5 h after prolactin treatment and continued to increase to maximum specific activities at similar rates. In thymus, the amount of ornithine decarboxylase present as a complex reached 70% of the total in the tissue. In both thymus and kidney, the concentration of antizyme-ornithine decarboxylase complex decreased more slowly than did free enzyme activity. Free antizyme was observed only in thymus of dexamethasone-treated animals. The amount of measurable inhibitor was decreased if cycloheximide was given with dexamethasone.     

A rat monoclonal antibody which interacts with mammalian ornithine decarboxylase at an epitope involved in phosphorylation

Ornithine decarboxylase was purified from androgen-treated mouse kidney to homogeneity and high specific activity. The purified enzyme was utilized for production and screening of rat monoclonal and polyclonal antibodies. A rat monoclonal antibody was isolated which was capable of immunoprecipitation of native mouse kidney ornithine decarboxylase activity or the [3H]difluoromethylornithine-inactivated enzyme. Phosphorylation of mouse ornithine decarboxylase by casein kinase-II prior to immunoprecipitation led to complete loss of the epitope recognized by the monoclonal antibody but did not alter recognition by polyclonal antibody. Mammalian ornithine decarboxylase activity obtained from several species, in crude or partially purified extracts, was subjected to quantitative immunoprecipitation with monoclonal and polyclonal antibody. Polyclonal antibody immunoprecipitated all of the ornithine decarboxylase activity from every extract tested, while monoclonal antibody was capable of only limited immunoprecipitation (60-80%). Due to the inability of the monoclonal antibody to recognize ornithine decarboxylase phosphorylated in vitro by casein kinase-II and the partial immunoprecipitation of ornithine decarboxylase activity from cell extracts, a portion of the ornithine decarboxylase molecule population must exist in a phosphorylated state. This immunological evidence further confirms existing data that the enzyme exists in at least two distinct forms.     

Increased activity of ornithine decarboxylase in tomato ovaries induced by auxin

Auxin, which mimics natural pollination in tomato flowers, induces fruit setting as well as a 3-fold increase in ornithine decarboxylase activity. In pollinated ovaries ornithine decarboxylase activity increased 4.7 fold. The possible connection between pollination, auxin treatment, fruit set, cell division and ornithine decarboxylase activity are discussed.     

Ornithine decarboxylase activity in insulin-deficient states

The activity of ornithine decarboxylase, the rate-controlling enzyme in polyamine biosynthesis, was determined in tissues of normal control rats and rats made diabetic with streptozotocin. In untreated diabetic rats fed ad libitum, ornithine decarboxylase activity was markedly diminished in liver, skeletal muscle, heart and thymus. Ornithine decarboxylase was not diminished in a comparable group of diabetic rats maintained on insulin. Starvation for 48h decreased ornithine decarboxylase activity to very low values in tissues of both normal and diabetic rats. In the normal group, refeeding caused a biphasic increase in liver ornithine decarboxylase; there was a 20-fold increase in activity at 3h followed by a decrease in activity, and a second peak between 9 and 24h. Increases in ornithine decarboxylase in skeletal muscle, heart and thymus were not evident until after 24–48h of refeeding, and only a single increase occurred. The increase in liver ornithine decarboxylase in diabetic rats was greater than in normal rats after 3h of refeeding, but there was no second peak. In peripheral tissues, the increase in ornithine decarboxylase with refeeding was diminished. Skeletal-muscle ornithine decarboxylase is induced more rapidly when meal-fed rats are refed after a period without food. Refeeding these rats after a 48h period without food caused a 5-fold increase in ornithine decarboxylase in skeletal muscle at 3h in control rats but failed to increase activity in diabetic rats. When insulin was administered alone or together with food to the diabetic rats, muscle ornithine decarboxylase increased to activities even higher than in the refed controls. In conclusion, these findings indicate that the regulation of ornithine decarboxylase in many tissues is grossly impaired in diabetes and starvation. They also suggest that polyamine formation in vivo is an integral component of the growth-promoting effect of insulin or some factor dependent on insulin.     

Regulation of ornithine decarboxylase activity by putrescine and spermidine in rat liver

The marked enhancement of the activity of ornithine decarboxylase (EC 4.1.1.17) in rat liver at 4 h following partial hepatectomy or the treatment with growth hormone could be almost completely prevented by intraperitoneal administration of putrescine. A single injection of putrescine to partially hepatectomized rats caused a remarkably rapid decline in the activity of liver ornithine decarboxylase with an apparent half-life of only 30 min, which is almost as rapid as the decay of the enzyme activity after the administration of inhibitors of protein synthesis. Under similar conditions putrescine did not have any inhibitory effect on the activity of adenosylmethionine decarboxylase (EC 4.1.1.50) or tyrosine aminotransferase (EC 2.6.1.5). Spermidine given at the time of partial hepatectomy or 2 h later also markedly inhibited ornithine decarboxylase activity at 4 h after the operation and, in addition, also caused a slight inhibition of the activity of adenosylmethionine decarboxylase.     

Amino acid decarboxylases in some fungi

The authors describe a method for the determination of decarboxylase activity in fungi. Some of the strains of test fungi (Stachybotrys alternans, Fusarium andAspergillus) displayed arginine, lysine, phenylalanine, asparaginic and glutamic decarboxylase activity. No tyrosine, tryptophane, histidine or ornithine decarboxylase activity was found. Some of the factors influencing the activity of these enzymes are discussed.     

The effects of nerve growth factor on polyamine metabolism in PC12 cells

Nerve growth factor treatment produces a large increase in the activity of ornithine decarboxylase and a moderate decrease in the activity of S-adenosylmethionine decarboxylase in PC12 cells. These changes are reflected weakly, if at all, in the levels of putrescine, spermidine, and spermine in the cells. The rates of polyamine synthesis are increased somewhat more than the overall levels, but still are not comparable in extent to the increase in the ornithine decarboxylase activity. Inhibitors of ornithine decarboxylase and S-adenosylmethionine decarboxylase have their expected effects on the induction of ornithine decarboxylase and on the activities of both enzymes. Neither inhibitor alone, nor a combination of inhibitors, altered the rate or extent of nerve growth factor-induced neurite outgrowth in the cells.