Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myocardial ornithine decarboxylase appears to have characteristics similar to those of enzymes isolated from other tissues. Ornithine decarboxylase activity decreased very rapidly after the death of the animal. Storage of the cell sap fraction at 0 degrees C or -15 degrees C, however, led to only a small decrease in the enzyme activity up to 3 days after preparation. Pyridoxal phosphate at an optimum of 50 muM was essential for full enzyme activity. Thiol compounds did not increase the myocardial ornithine decarboxylase enzyme activity. The subcellular distribution of the enzyme in the myocardium was found to be different from that reported in other tissues. A partial purification of the enzyme was possible using the proteins precipitated at pH 5 from a cell-soluble fraction or by passing a soluble fraction through a Sephadex G 100 gel column. ATP, ADP, and AMP inhibited ornithine decarboxylase at high concentrations (5 mM), but GTP, CTP, and ITP inhibited at a 1 mM concentration and above.
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PMID:Some properties of rat myocardial ornithine decarboxylase and the in vitro effects of nucleotides. 0 62

A transient rise in cyclic guanosine 3' : 5' monophosphate (c-GMP) in the liver was observed in rats in vivo 10--20 min after partial hepatectomy. A similar increase in c-GMP in the liver was also found in rats in vivo 15 min after infusion of TGH solution (a mixture of triiodothyronine, glucagon, and heparin). In both cases, inductions of ornithine decarboxylase [EC 4.1.1.17] and tyrosine aminotransferase [EC 2.6.1.5] were found 4 hr after the beginning of the experiments. Later, 22 hr after the surgical intervention or hormone infusion, thymidine kinase [EC 2.7.1.21] was activated and liver slices were able to incorporate [3H]thymidine into DNA. These biochemical phenomena were observed commonly in regenerating liver as well as in the liver of rats infused with TGH solution. c-GMP, but not c-AMP, could induce ornithine decarboxylase and tyrosine aminotransferase in isolated, perfused liver.
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PMID:Involvement of cyclic GMP in the initial stage of hepatocytes proliferation. 1 43

Both exposure to cold and administration of aminophylline result in rapid increases in cyclic adenosine monophosphate (cyclic AMP) in the adrenal medulla and adrenal cortex. These increases are followed by dramatic increases in ornithine decarboxylase activity is due to new enzyme systhesis. The data suggest that the decarboxylase activity is regulated by an increase in cyclic AMP.
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PMID:Ornithine decarboxylase activity: control by cyclic nucleotides. 16 86

We studied the effects of TSH on rat thyroid ornithine decarboxylase (ODC) activity. After 1 day of goitrogen treatment, there was an abrupt fall in serum triiodothyronine (T3) a rise in circulating TSH, and a dramatic increase in thyroid ODC activity. Despite the continued rise in TSH and progressive increase in thyroid gland size with further treatment, thyroid ODC activity declined on the third day and remained at submaximal levels. Thyroid ODC activity was also stimulated in a dose-related manner by administration of exogenous TSH. Little TSH effect was noted before 3 h. Maximal ODC activity occurred between 4 and 5 h. The TSH stimulation of ODC could be inhibited by pretreatment with actinomycin D or cycloheximide, suggesting that the increase in ODC activity requires new RNA and protein synthesis. Although pretreatment with agents that alter microtubule structure (e.g., colchicine and vinblastine) prevent stimulation of ODC activity by TSH, additional data suggest, but do not confirm, that hrmone secretion and ODC activation may be dissociable. Further studies were undertaken to determine whether cyclic AMP (cAMP) or prostaglandins played any role in the regulation of thyroidal ODC activity. Dibutyryl cAMP, alone, or together with aminophylline, did not stimulate thyroidal ODC activity in dosages which concomitantly stimulated adrenal enzyme activity. Likewise, prostaglandin E2 (PGE2) did not stimulate thyroidal ODC activity, but did stimulate adrenal enzyme activity in a dose-related manner. However, pre-treatment of rats with inhibitors of prostaglandin synthesis prevented the activation of thyroidal ODC BY TSH. One inhibitor, indomethacin, attenuated the TSH stimulation of enzyme activity in a dose-related manner. Indomethacin pretreatment also resulted in approximately a 10-fold decrease in thyroidal prostaglandin levels. Exogenous PGE9, in dosages as high as 500 pg, did not overcome the inhibitory effect of indomethacin on ODC activation. Although the precise role for endogenous prostaglandins remains to be defined, it does appear that a reduction in thyroidal prostaglandins prevents activation of the enzyme by TSH.
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PMID:Regulation of thyroid ornithine ornithine decarboxylase (ODC) by thyrotropin. I. The rat. 16 59

Chinese hamster V79 cells were synchronized by mitotic selection, which resulted in approximately 95% synchrony. The adenosine 3':5'-cyclic monophosphate level was elevated within 3 hr (G1 phase) and reached a level 2-fold higher than in early G1 within 6 hr (early S phase). An increase in ornithine decarboxylase activity (6-ornithine carboxy-lyase, EC 4.1.1.17), the initial enzyme in the polyamine biosynthetic pathway, was detected within 4 hr and was maximal at 8 hr. Since about 20% of the cells were labeled with [3-H]thymidine at 4 hr, ornithine decarboxylase exhibits cell-cycle specific activity starting in late G1 and continuing through middle S phase. The activity of S-adenosylmethionine decarboxylase (S-adenosyl-L-methionine carboxylase, EC 4.1.1.50) increased within 5 hr, i.e., early S phase. It is suggested on the basis of these data and other studies discussed herein that the increase in ornithine decarboxylase activity, which parallels closely the elevation in cyclic AMP, is an example of adenosine 3':5'-cyclic monophosphate-mediated protein synthesis.
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PMID:Cell cycle specific fluctuations in adenosine 3':5'-cyclic monophosphate and polyamines of Chinese hamster cells. 16 12

The mechanism of action of adrenocorticotrophin (ACTH) stimulation of rat adrenal orticotrophin (ACTH) stimulation of rat adrenal ornithine decarboxylase activity was investigated. ACTH induction or ornithine decarboxylase activity was not prevented by administration of drugs that inhibit adrenal steroid biosynthesis. A dose of ACTH that produced maximal levels of adrenal cyclic AMP did not induce ornthine decarboxylase activity. Ovine growth hormone, which caused no increase in adrenal cyclic AMP, stimulated adrenal ornithine decarboxyase activity. These observations suggest that the increase in adrenal ornithine decarboxylase activity stimulated by ACTH is not dependent upon steroidogenesis, nor is it dependent on the early peak of cyclic AMP, although it may be influenced by the sustained levels of tissue cyclic AMP that follow the administration of large doses of ACTH. Furthermore, it appears there may be a pathway of ornithine decarboxylase activation in the adrenal which is entirely independent of cyclic AMP mediation. The effects of hypophysectomy on adrenal ornithine decarboxylase response to ACTH were examined. In rats given ACTH 16 h after hypophysectomy, the increase in ornithine decarboxylase activity was delayed when compared with the response in animals given ACTH 1 h after hypophysectomy. Actinomycin D given during the first 3 h after ACTH in the 16 h hypophysectomized rat abolished the expected increase in ornithine decarboxylase activity. Thereafter, a progressive increase in ornithine decarboxylase activity was observed as the interval between ACTH and Actinomycin D administration was further increased. In contrast, Actinomycin D administered 15 min before ACTH in the 1 h hypophysectomized rat had no effect on the subsequent increase in ornithine decarboxylase activity, and actually progressively enhanced the response the longer its administration after ACTH was delayed. Cycloheximide abolished the response to ACTH in both the 1 h and the 16 h hypophysectomized rat. Thus, it appears that ACTH stimulates a post-transcriptional mechanism regulating ornithine decarboxylase activity in the acutely hypophysectomized animal, whereas, in the chronically hypophysectomized rat, ACTH must first stimulate transcription of new messenger RNA which is involved in regulation of adrenal ornithine decarboxylase synthesis.
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PMID:The mechanism of ACTH stimulation of adrenal ornithine decarboxylase activity. 16 25

After partial hepatectomy in rats, the following changes in enzymic activities were observed in the remnant liver during the prereplicative period. In the initial period of the prereplicative process, soon after removal of part of the liver, ornithine decarboxylase [EC 4.1.1.17] and IMP dehydrogenase [EC 1.2.1.14] increase. Subsequently, for entry into the S period, thymidine kinase [EC 2.7.1.75] increases simultaneously with increase in the intracellular cyclic AMP level and decrease in its phosphodiesterase [EC 3.1.4.17].
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PMID:Prereplicative enzymic changes in regenerating rat liver. 16 85

TSH (1.0 U im) caused a 22-fold increase in thyroidal ornithine decarboxylase activity (ODC) 6 hours after administration in intact rats. Hypophysectomized rats treated with 1 U TSH showed a 5-fold increase in thyroid ODC activity. This stimulation appeared to be specific for TSH since hormones known to induce ODC activity in other target tissues, such as ACTH or LH, showed no significant stimulation. DIBUTYRYL CYCLIC AMP and aminopylline caused a 12-fold increase in ODC activity 5 hours after administration. Prostaglandins have also been implicated in the TSH-induced stimulation of cyclic AMP. Indomethacin (1.0 mg/100 g body wt, ip), an inhibitor of prostaglandin synthesis, was administered 3 hours before TSH with a resulting 30% diminution (P less than .001) in ODC activity compared with the administration of TSH alone. To rule out the possibility that the increase in ODC activity with TSH might be due to increased thyroid hormone secretion, ODC activity was evaluated 6 hours after triiodothyronine administration (60 mug/100 g body wt), and no significant increase in thyroid ODC activity was found. Stimulation of ODC activity was 90% inhibited by the intraperitoneal administration of actinomycin D (80 mug/100 g body wt) or cycloheximide (400 mug/100 g body wt) given simultaneously with TSH. These results indicated that TSH specifically stimulated thyroid ODC activity, which may be important for the growth-promoting action of the hormone on the thyroid gland. This action may be mediated by cAMP and prostaglandins and may require new protein synthesis.
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PMID:Thyroid-stimulating hormone regulation of ornithine decarboxylase activity in the thyroid. 17 Nov 42

The activity of ornithine decarboxylase increases markedly in a biphasic manner during the hormone-dependent development of mouse mammary epithelium in vitro. The first peak of activity occurring at 3 to 4 hours of culture was elicited by incubating mammary explants in a culture medium without any added hormones, although addition of insulin or prolactin, or both, caused a greater increase. The emergence of the second peak of activity at about 12 hours depended on the actions of both insulin and prolactin. A second increase in activity could also be effected postmitotically by the delayed addition of prolactin. Studies with actinomycin D and cycloheximide suggest that the first increase in enzyme activity may be effected at a post-transcriptional level, whereas a second increase may be at both transcriptional and translational levels. During the first 3 hours of incubation, there was a rapid, transient increase in cyclic AMP concentration in mammary epithelium. The presence of insulin or prolactin in culture did not affect the change in epithelial cyclic AMP concentration. Addition of several derivatives of cyclic AMP, 0.1 to 0.5 mM, as well as prostaglandin E1, a stimulator of adenylate cyclase, resulted in enhancement of the first increase in enzyme activity. The effect of cyclic nucleotide was additive to that of insulin and prolactin and appears to be mediated at a post-transcriptional level. The stimulatory effect of a lower concentration of both the cyclic nucleotide and prostaglandin E1 was augmented by theophylline, an inhibitor of phosphodiesterase. These results may suggest possible involvement of cyclic AMP in the first increase in enzyme activity that occurs in the absence of any added hormones.
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PMID:Studies on regulatory factors of ornithine decarboxylase activity during development of mouse mammary epithelium in vitro. 17 59

Ornithine decarboxylase has been induced in log phase hepatoma cells grown in suspension culture. Induction with N6, O2'-dibutyryl cyclic adenosine 3':5'-monophosphate produced a 4-fold increase in enzyme activity by 3 hours which was followed by a return to base levels by 6 hours. Induction with dexamethasone, a potent synthetic glucocorticoid, exhibited a slow steady rate of increase in enzyme activity, reaching a plateau level of approximately 5- to 6-fold stimulation by about 12 hours. Induced cell and regenerating rat liver ornithine decarboxylase were shown to be indistinguishable by titration with antibody monospecific to the latter and by heat stability. L-[14C]Leucine incorporation into immunoprecipitable enzyme protein after induction in vitro or partial hepatectomy showed an increase which, when coupled with the increase in enzymatic activity, indicated de novo synthesis of enzyme protein. Physiological concentrations of the naturally occurring polyamines, spermidine and spermine, abolish cyclic AMP induction whereas they have no effect on dexamethasone induction. Both inductions were abolished by cycloheximide; in contrast, inhibition by actinomycin D was complete for dexamethasone induction and only partial with respect to cyclic AMP induction. The different time pattern of induction seen with cyclic AMP and dexamethasone, the partial inhibition of the cyclic AMP induction seen with actinomycin D, as well as the absence of inhibition of the dexamethasone induction by polyamines, indicate that these inducers might affect different aspects of the control of the same enzyme.
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PMID:Stimulation of ornithine decarboxylase synthesis and its control by polyamines in regenerating rat liver and cultured rat hepatoma cells. 18 26


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