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)

Ornithine decarboxylase activity increases 2-fold above control after 1 day and 25-fold after 3 days of exposure to 0.85 atm oxygen. Putrescine content nearly doubled by 72 hours which may reflect increased activity or ornithine decarboxylase. Spermidine and spermine content did not increase until after 3 days of exposure which was consistent with the delayed increase of S-adenosylmethionine decarboxylase activity. The results suggest that antimetabolites of polyamine metabolism may be useful to suppress excessive cellular proliferation in the lung after acute lung injury.
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PMID:Polyamine metabolism in rat lungs with oxygen toxicity. 687 Aug 72

We have selected a mutant of Chinese hamster ovary cells that is severely deficient in ornithine decarboxylase activity and is auxotrophic for putrescine. The mutant we obtained (C54) has only 3% of the maximum inducible ornithine decarboxylase activity of the parental Chinese hamster ovary cells and the rate of incorporation of [3H]ornithine into acid-soluble material is correspondingly reduced. The defect in the mutant was recessive in somatic cell hybrids. The mutant requires at least 10(-5) M putrescine in the medium to maintain a normal growth rate. Spermidine and spermine can also serve as a polyamine source, and very high (millimolar) concentrations of ornithine can support a normal growth rate. In the absence of polyamine supplementation the cells stop growing after about 3 population doublings and begin to die after 5 or 6 days. The intracellular concentrations of putrescine and spermidine are depleted after 24 and 48 h, respectively. Spermine levels remain essentially constant for 4 days. Unexpectedly, the Km for ornithine of the enzyme from mutant cells was consistently somewhat lower than the Km for the enzyme from wild type cells. It is possible but not yet certain that the mutant is the result of a mutation in the structural gene coding for ornithine decarboxylase.
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PMID:An ornithine decarboxylase-deficient mutant of Chinese hamster ovary cells. 706 54

Some characteristics of L-ornithine decarboxylase of tomato ovaries and tobacco cells are described. The enzyme has a pH optimum of 8.0. It requires pyridoxal phosphate and thiol reagent (dithiothreitol) for activity. It is specific for L-ornithine and has an apparent Km of 1.4 X 10-4 M. It has an apparent molecular weight of 107000. Putrescine inhibited the activity in vitro. Spermidine and spermine also inhibit the enzyme, but less effectively. It is concluded that the enzyme is similar to that of mammalian origin and likewise fulfils a function related to cell proliferation.
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PMID:Characterization of ornithine decarboxylase of tobacco cells and tomato ovaries. 708 96

The polyamines putrescine, spermidine and spermine are intimately associated with cellular growth and division. Previous studies of the polyamines and their rate limiting biosynthetic enzyme, ornithine decarboxylase, in psoriasis have shown significant changes compared with non-psoriatic skin. We have further studied cutaneous polyamines in patients with psoriasis and in normal subjects, epidermal shave biopsies were taken and assayed for ornithine decarboxylase activity and polyamine levels. Psoriasis lesions showed increased ornithine decarboxylase activity compared with uninvolved skin. The levels of ornithine decarboxylase activity in uninvolved psoriasis skin were also higher than in normals. There was increased putrescine in involved psoriasis compared with uninvolved and normal skin. Spermidine and spermine were increased in psoriasis skin and in uninvolved skin and compared with normals. The spermidine/spermine ratio was greatest in involved skin compared with uninvolved and normal. These results confirm abnormal polyamine metabolism in both the involved and uninvolved skin of psoriatics.
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PMID:Cutaneous polyamines in psoriasis. 710 6

The enzyme catalysing the polyamine-stimulated modification of Physarum ornithine decarboxylase in vivo was partially purified and its activity on purified ornithine decarboxylase was examined with respect to its specificity for various amines. Spermidine, spermine and several polyamine analogues strongly promoted this reaction in vitro (apparent Km in the 0.1--0.5 mM range), whereas putrescine (apparent Km 5.33 mM) and several related diamines were not nearly as effective. In agreement with this, sensitivity studies performed in vivo also suggested that cellular spermidine, and not putrescine, is critical in modulating ornithine decarboxylase activity by this post-translational control. Unlike putrescine, or other diamines, 1,3-diaminopropane demonstrated a functional similarity to the polyamines in stimulating this reaction. This study has demonstrated a method whereby non-physiological amines capable of depressing ornithine decarboxylase activity by this natural feedback mechanism can be readily identified for further evaluation of their potential use in the experimental and medical control of polyamine biosynthesis.
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PMID:Amine-specificity of the inactivating ornithine decarboxylase modification in Physarum polycephalum. 715 Feb 32

Prostatic binding protein (PBP), polyamine, and DNA synthesis were examined in primary cultures of rat ventral prostate cells. Soon after aggregates of prostate cells were placed in culture, PBP synthesis fell dramatically and DNA synthetic activity in the epithelial cells increased. The amount of polyamines that were labeled with [3H] from [3H] ornithine fell transiently, but rose again at or before the peak of DNA synthesis. Individual 3H-labeled polyamines in cells and medium were dansylated and separated by thin-layer chromatography. The ratio of [3H] Spermidine plus [3H] Spermine to [3H] Putrescine in the culture medium declined as DNA synthesis increased. Ornithine decarboxylase (ODC) activity fell dramatically along with PBP synthesis even as DNA synthesis and 3H-labeled polyamines increased in the prostate-cell cultures. These results support others that suggest that high ODC activity in prostate epithelial cells is a correlate of prostate epithelial cell function rather than proliferation. However, prostate epithelial cells retain the capacity to synthesize significant levels of polyamines from ornithine (especially Putrescine) during proliferation even when ODC activity is low.
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PMID:Prostatic binding protein, polyamine, and DNA synthesis in rat ventral prostate cells. 720 37

Measurements of ornithine decarboxylase (ODC) activity and of the amounts of putrescine, spermidine and spermine in the placenta and uterus of the pregnant rat and in decidual tissue of the pseudo-pregnant rat showed that these wax and wane with the growth rate of the tissues. Human term placenta has essentially no ODC activity, but placentae from 15-week human gestations have substantial amounts of enzyme. The ODC activity of the rat placenta increases 40-fold from day 10 to day 17 of pregnancy, then gradually decreases. The content of the polyamines in the placenta also reaches a peak on day 17. The ODC activity of the endometrium between implantation sites remains low until the end of pregnancy and then increases eight-fold on days 21 and 22. This may represent increased uterine activity in preparation for parturition. The ODC activity and the polyamine content of decidual tissue responds to administered oestradiol with increases that reach a peak within four hours. The ODC activity and polyamine content of decidual tissue decrease after the fifth day of decidualization. Nuclei isolated from decidual tissue respond to the addition of spermine or spermidine with an increase in the rate of RNA synthesis. Spermidine increases the elongation of RNA chains, but does not initiate the synthesis of new RNA chains in decidual nuclei.
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PMID:Ornithine decarboxylase activity and polyamine content of the placenta and decidual tissue in the rat. 723 33

Rat liver cytosol extracts catalyzed the formation of monoacetylspermidine when incubated with acetyl-CoA and spermidine. This activity was enhanced 15-fold by administration of thioacetamide (150 mg/kg). The peak of activity occurred 18-24 h after treatment with the drug and then declined reaching control levels by 76 h. Previous studies have shown that ornithine decarboxylase activity was also greatly increased over this time period. Putrescine content in the liver was increased 80-90-fold at 18-24 h and then declined. Spermidine levels were decreased significantly over the period 12-24 h after thioacetamide treatment and then increased substantially at later times. These results are consistent with the hypothesis that, at early times after administration of thioacetamide, the increase in putrescine content is brought about both by decarboxylation of ornithine and by degradation of monoacetylspermidine. Spermidine acetylase activity was also measured in liver extracts prepared after two other physiological stimuli known to enhance ornithine decarboxylase activity were used. Both growth hormone treatment and partial hepatectomy produced an early 2-3-fold increase in the cytosolic spermidine acetylase activity.
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PMID:Effect of thioacetamide, growth hormone or partial hepatectomy on spermidine acetylase activity of rat liver cytosol. 744 8

Ornithine decarboxylase (ODC), the first and rate-limiting enzyme of polyamine metabolism, has been shown to be required for entry into and progression through the cell cycle. However, the role of ODC and polyamines in apoptosis remains to be determined. We have examined ODC expression and polyamine levels in thymocytes activated to undergo apoptosis by dexamethasone treatment. We have demonstrated a rapid and reversible induction of ODC (mRNA and activity), as previously reported for the mRNA expression of other "early" genes, c-fos, c-jun, and c-myc, in the same experimental model. Surprisingly, polyamine levels diminished progressively starting at 2-4 h after dexamethasone treatment, and spermine was depleted at 8-12 h. This seemed to be relevant since increasing the intracellular polyamine levels by exogenous spermine administration prevented the DNA "laddering" (2-4 h) and the DNA loss from the nucleus (8-18 h) due to dexamethasone treatment. Moreover, the activities of spermidine/spermine N1-acetyltransferase, which controls the cytosolic polyamine interconversion pathway, and of spermidine N8-acetyltransferase, which regulates the nuclear pool and functions of polyamines, were measured in apoptotic cells. Spermidine/spermine N1-acetyltransferase activity progressively increased and might be responsible for spermidine and spermine excretion as acetyl derivatives. In contrast, spermidine N8-acetyltransferase activity remained unchanged. A completely different scenario was observed in proliferating concanavalin A-treated thymocytes, studied for comparison. In this case, polyamine levels increased, remaining at high values until 12 h. This is likely a consequence of the rapid and prolonged induction of ODC (mRNA and activity), accompanied by that of spermidine/spermine N1-acetyltransferase (mRNA and activity).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Involvement of ornithine decarboxylase and polyamines in glucocorticoid-induced apoptosis of rat thymocytes. 764 33

Nutritional repletion of tumor-bearing (TB) organisms by means of total parenteral nutrition (TPN) has been associated with gut atrophy, immunosuppression, and increased infection rate. To assess possible molecular mechanisms of intestinal atrophy during TPN, jejunal mucosal polyamine concentrations and biosynthetic activity were assessed in non-TB (NTB) and TB rats maintained on rat chow or TPN for eight days. As expected, jejunal mucosal protein content was decreased in both groups of rats maintained on TPN. Although mucosal concentration of putrescine was decreased in TB groups and in the NTB group maintained on TPN, levels of spermidine and spermine were decreased only in the NTB-TPN group. Spermidine levels were elevated significantly in both TB groups. The concentration of spermine was also elevated in the TB-TPN group but was not changed in the TB group maintained on chow. Activity of ornithine decarboxylase was increased in the NTB-TPN group but was not altered significantly in either TB group. S-adenosylmethionine decarboxylase activity was decreased significantly in TB rats maintained on chow and was increased back to control level in the TB-TPN group. These results suggest that jejunal mucosal polyamines are decreased in NTB rats maintained on TPN. Additionally, it appears that enzyme activity is induced in NTB-TPN rats, perhaps in response to the reduction in polyamines and gut atrophy. The absence of similar changes in TB rats maintained on TPN suggests that regulatory mechanisms of polyamine biosynthesis, such as product inhibition, may be refractory. In addition, polyamine biosynthesis from other sources, such as tumor tissue, may be affecting the control of intestinal polyamine biosynthesis.
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PMID:Differential effects of tumor and parenteral nutrition on jejunal mucosal polyamines. 773 12


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