Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Hypoosmotic stress is a potent inducer of ornithine decarboxylase (ODC) activity in a variety of mammalian cells, but the physiological relevance of this response has not been determined. To test whether an increased putrescine content confers a growth advantage at lower osmolarities, we compared the ability of L1210 mouse leukemia cells and of ODC-overproducing variants obtained from this cell line (D-R cells) to proliferate after a hypotonic shock (325----130 mosmol/kg). The growth rate of D-R cells at 130 mosmol/kg was greater than or equal to 5-fold higher than in L1210 cells; and unlike the ODC-overproducing strain, L1210 cells underwent up to a 90% loss of viability over time as seen after restoration of normosmotic growth conditions and by trypan blue exclusion tests. The addition of putrescine or L-ornithine stimulated the proliferation of both cell sublines up to 5-fold in a concentration-dependent manner, with a maximal effect observed at about 10 and 100 microM, respectively. Putrescine restored virtually normal growth rates in both sublines at osmolarities as low as 190 mosmol/kg. No other alpha,omega-diamine was active in that respect whereas spermidine was markedly inhibitory. Furthermore, D-R cells incubated at 130 mosmol/kg showed a marked growth inhibition by 1-aminooxy-3-aminopropane (potent ODC inhibitor to which they are resistant in isotonic media) as a result of putrescine but not spermidine depletion. Whereas ODC was strongly and rapidly induced by hypotonic shock there was a precipitous decline in S-adenosylmethionine decarboxylase activity. Putrescine synthesis and accumulation were nevertheless reduced in D-R cells incubated at 130 mosmol/kg because of a decreased availability of L-ornithine. When either putrescine or L-ornithine was added to hypotonic media, D-R cells accumulated putrescine massively for extended periods together with a reduction in spermidine and spermine contents. Putrescine transport patterns were altered by hypotonic shock, net excretion of the diamine being reduced by about 80%, with a concurrent enlargement of the intracellular pool. Finally, parental L1210 cells incubated with an irreversible inhibitor of S-adenosylmethionine decarboxylase for 24 h until hypotonic shock and supplemented with putrescine in the presence of the drug thereafter exhibited a greatly exaggerated growth stimulation by the diamine. These results demonstrate an essential role for an early increase in putrescine content in the growth adaptation of a mammalian cell line to a lower osmolarity.
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PMID:An early enlargement of the putrescine pool is required for growth in L1210 mouse leukemia cells under hypoosmotic stress. 200 73

Ornithine decarboxylase (ODC) activity is known to be strongly enhanced in mammalian cells by a sudden reduction in ambient osmolality. The effect of hypoosmotic shock on the regulation of ODC protein and mRNA levels was studied in a variant L1210 mouse leukemia cell line (D-R cells) which expresses ODC at greater than or equal to 100-fold higher levels than the parental cells. Hypoosmotic stress increased ODC activity in proportion with the osmotic gradient imposed to both D-R cells and their normal counterparts. A 60% decrease in medium osmolality increased ODC activity and the amount of immunoreactive ODC protein from 20- to 30-fold after 4 h without any detectable change in ODC mRNA contents in D-R cells. ODC induction was sustained up to 48 h after hypoosmotic shock, with maximal activity levels being observed at 24 h. Hypotonic shock dramatically increased (up to 36-fold) the rate of ODC synthesis as measured by 10-min pulses with 35S-labeled methionine, in agreement with kinetic constants predicted from the changes observed for the enzyme activity. Moreover, hypoosmotic stress extended the half-life of ODC activity from 35 +/- 10 to 212 +/- 67 min and blocked any degradation of the radiolabeled immunoreactive protein, which had a half-life of 28 +/- 6 min under isotonic conditions, for at least 120 min after addition of cycloheximide. The induction of ODC by hypoosmotic stress was quickly reversed by a sudden upshift of osmolality through a very rapid inhibition of ODC biosynthesis and an increase in the rate of enzyme degradation. Thus, hypoosmotic stress activates the expression of ODC exclusively through post-transcriptional mechanisms in D-R cells. The osmotically induced accumulation of ODC molecules is quite unique as shown by the fact that ODC is the major protein (approximately 25% of total) synthesized during the first 4 h following a 60% hypotonic shock, despite a 30-50% reduction of the rate of labeled precursor incorporation into soluble proteins.
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PMID:Regulation of ornithine decarboxylase expression by anisosmotic shock in alpha-difluoromethylornithine-resistant L1210 cells. 210 57

The expression of the myeloperoxidase (MPO) gene was studied, by means of Northern blot analysis in 14 cases of acute myeloid leukemia (AML), 11 cases of chronic myeloid leukemia (CML), and 6 cases of CML blast crisis, and in HL60 cells before and after induction of terminal differentiation with retinoic acid (RA), phorbol esters (TPA), or vitamin D. The expression of a panel of cell cycle-related genes, namely C-MYC, histone H3, ornithine decarboxylase, P53, vimentin, and calcyclin, was also studied in the same cell populations. Our results indicate that: (a) MPO gene expression (steady state mRNA levels) is strictly confined to the first stages of myeloid differentiation, reaching its peak at the promyelocyte stage and becoming undetectable in mature granulocytes and monocytes; (b) cells devoid of any detectable MPO enzymatic activity such as leukemic basophils have a high content of MPO mRNA; and (c) MPO gene expression is not related to the growth activity of the cell population. Finally, our results show that the pattern of expression of growth-regulated genes in the neoplastic myeloid disorders AML, CML, and CML blast crisis is remarkably different.
Leukemia 1989 Jun
PMID:Expression of the myeloperoxidase gene in acute and chronic myeloid leukemias: relationship to the expression of cell cycle-related genes. 254

The authors have assayed the level of expression of several cell-cycle related genes in several populations of circulating myeloid leukemic blast cells. The genes explored included oncogenes such as c-myc, c-myb, p53, and cell-cycle-related genes such as vimentin, calcyclin, ornithine decarboxylase (ODC) and histone H3. Particular attention was given to analysis of the relationship existing between the mRNA levels of the histone H3 gene, which is expressed specifically in the S phase of the cell cycle, and the levels of other genes that are expressed in different stages of the G1 phase. Remarkable differences were observed among the different cases indicating that a differential expression of cell-cycle-related genes characterizes many acute leukemias. This differential expression is reflected in an altered ratio among G1-related genes and the H3 histone gene. The large fraction of leukemic cells which does not express histone H3 and therefore is functionally noncycling, shows a heterogeneous pattern of G1-related gene expression. This reflects the inability of most leukemic cells to progress through the G1 phase into the S phase of the cell cycle. This inability represents an abnormality of the cell cycle. It is concluded that the study of the expression of cell-cycle genes and protooncogenes in in understanding how leukemic cells enter a state of proliferation arrest, which appears to occur in a large fraction of leukemic cells.
Leukemia 1988 Dec
PMID:Expression of oncogenes and cell cycle related genes in acute and chronic leukemias. 319 78

Three out of four different mycoplasma strains analysed for the polyamine contents contained relatively high concentrations of putrescine, cadaverine, spermidine and spermine. In addition to ornithine decarboxylase (EC 4.1.1.17) activity, the mycoplasmas also exhibited comparable or higher lysine decarboxylase (EC 4.1.1.18) activity fully resistant to the action of 2-difluoromethylornithine, an irreversible inhibitor of eukaryotic ornithine decarboxylase. 2-Difluoromethylornithine did not modify the polyamine pattern of actively growing mycoplasmas. Ehrlich ascites carcinoma cells and L1210 mouse leukemia cells infected with any of the four mycoplasma strains contained, in addition to putrescine, spermidine and spermine, and also easily measurable concentrations of cadaverine; the latter diamine was absent in uninfected cultures. When the infected cells were exposed to difluoromethylornithine, the accumulation of cadaverine was markedly enhanced. The modification of cellular polyamine pattern by mycoplasmas, especially in the presence of inhibitors of eukaryotic ornithine decarboxylase, could conceivably be used as an indicator of mycoplasma infection in cultured animal cells.
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PMID:Polyamines in mycoplasmas and in mycoplasma-infected tumour cells. 680 70

The D-R cell subline, an ornithine decarboxylase-overproducing variant of L1210 mouse leukemia cells, shows a growth advantage at low osmolality due to its high putrescine content. We tested the ability of spermidine to fulfill the role of putrescine under hyposmotic conditions. Although spermidine (1-30 microM) had no effect on growth under normosmotic conditions (325 mosm/kg), it was strongly inhibitory to D-R cell proliferation at 150 mosm/kg in a concentration-dependent manner. Hypotonic shock greatly increased the rate of spermidine uptake in D-R cells. The increased spermidine content enhanced total putrescine synthesis through a large induction of cytosolic spermidine/spermine N1-acetyltransferase activity but also promoted the excretion of most of the putrescine synthesized by the cells. Delaying the addition of spermidine until 24 h after hypotonic shock resulted in a much sharper decrease in D-R cell viability and strongly depressed polyamine contents. These lethal effects occurred between 8 and 24 h after spermidine addition and followed a dramatic increase in the rate and extent of spermidine accumulation which overrode the metabolic capacity of the N1-acetyltransferase/polyamine oxidase (PAO) pathway. Inhibition of PAO partly reversed the effect of spermidine on growth when the polyamine was added at the time of hypotonic shock, but not 24 h later. Similar experiments performed with alpha-methylspermidine, a metabolically resistant analog, which can completely fulfill cellular requirements for spermidine in normosmotic media, suggested that the lethal effect of a delayed spermidine addition is caused predominantly by excessive accumulation with a minor contribution resulting from stress due to polyamine oxidase activity. In contrast, in hypotonically shocked L1210 cells, spermidine stimulated cell proliferation (albeit less effectively than putrescine), there was no lethal effect of a delayed addition of alpha-methylspermidine, and there was no time-dependent increase in the rate of alpha-methylspermidine uptake. Thus, the spermidine transport system is strongly enhanced by hyposmotic shock in D-R cells, which can result in extensive cell death from overaccumulation of the polyamine and, to a lesser extent, from stress related to the PAO-catalyzed degradation of N1-acetylspermidine. The absence of these effects in parental L1210 cells indicates that the acquisition of an ornithine decarboxylase-overproducing phenotype also involves major modifications in the expression and/or regulation of polyamine transport.
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PMID:Enhancement of the spermidine uptake system and lethal effects of spermidine overaccumulation in ornithine decarboxylase-overproducing L1210 cells under hyposmotic stress. 844 43

Oxidation by copper/quinone-containing serum amine oxidases (SAO) is a well-known cause of polyamine cytotoxicity. Spermine oxidation exerts potent immunosuppressive effects in animal cells, but the cell death mechanism involved remains unclear. We compared biochemical and morphological parameters of SAO-mediated cell death in L1210 mouse leukemia cells with normal or amplified ornithine decarboxylase gene expression with those observed during apoptosis induced by deregulated polyamine uptake or by okadaic acid. None of the characteristic features of apoptotic cell death (e.g., chromatin condensation, nuclear fragmentation, internucleosomal DNA cleavage, poly(ADP-ribose) polymerase cleavage) were observed during spermine oxidation-mediated cell death, which was clearly necrotic by morphological criteria. Inhibition of a wide spectrum of caspases did not prevent SAO-dependent cell death, whereas N-acetylcysteine completely abolished the cytotoxic effects of spermine oxidation. Catalase only delayed spermine oxidation-induced cell death without affecting its modality or preventing depletion of intracellular glutathione, suggesting that both H(2)O(2) and aminoaldehydes generated by SAO-mediated spermine oxidation contribute to SAO-induced necrosis. Interestingly, redistribution of phosphatidylserine to the outer leaflet of the plasma membrane, usually a diagnostic feature of apoptosis, preceded necrotic cytolysis triggered by spermine oxidation. Thus, L1210 cell death caused by SAO-mediated spermine oxidation has all the attributes of primary necrosis, but is also accompanied by loss of phospholipid asymmetry, indicating that the latter phenomenon may not be unique to apoptosis. Phosphatidylserine exposure, a potent engulfment signal for phagocytes, might contribute to the immunosuppressive effects of plasma polyamines through a controlled and rapid necrotic process involving SAO.
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PMID:Spermine oxidation leads to necrosis with plasma membrane phosphatidylserine redistribution in mouse leukemia cells. 1094 76

The balance between hematopoietic cell viability and apoptosis is regulated by exogenous growth factors, however, the molecular mechanisms by which these trophic factors exert their effects remain obscure. A functional retroviral cDNA library-based screen was employed to identify genes that prevent growth factor withdrawal-mediated apoptosis in the myeloid progenitor cell 32Dcl3. This approach identified three classes of genes: those with known roles in apoptosis (bcl-X(L) and ornithine decarboxylase); genes previously identified but not linked directly to apoptotic signaling (O-linked N-acetylglucosamine transferase); and a previously uncharacterized gene we termed SPIN-2. In 32Dcl3 cells, expression of exogenous SPIN-2 provides 25% protection from apoptosis following growth factor withdrawal compared to controls which show approximately 1-2% survival. SPIN-2 overexpression slows cell growth rates and increases the percentage of cells in G(2)/M (32% vs control cells at 12%). Immunolocalization studies indicate that myc-epitope tagged SPIN-2 proteins, which retain their anti-apoptotic function, reside in the nucleus, whereas a C-terminal deletion mutant that loses its anti-apoptotic activity is located in the cytoplasm. These studies suggest that SPIN-2 is a novel nuclear protein that functions to regulate cell cycle progression and this activity is related to the inhibition of apoptosis following the removal of essential growth factors.
Leukemia 2002 Aug
PMID:Functional cloning of SPIN-2, a nuclear anti-apoptotic protein with roles in cell cycle progression. 1214 92

Evading apoptosis is a cancer hallmark that remains a serious obstacle in current treatment approaches. Although proteasome inhibitors (PIs) have transformed management of multiple myeloma (MM), drug resistance emerges through induction of the aggresome+autophagy pathway as a compensatory protein clearance mechanism. Genome-wide profiling identified microRNAs (miRs) differentially expressed in bortezomib-resistant myeloma cells compared with drug-naive cells. The effect of individual miRs on proteasomal degradation of short-lived fluorescent reporter proteins was then determined in live cells. MiR-29b was significantly reduced in bortezomib-resistant cells as well as in cells resistant to second-generation PIs carfilzomib and ixazomib. Luciferase reporter assays demonstrated that miR-29b targeted PSME4 that encodes the proteasome activator PA200. Synthetically engineered miR-29b replacements impaired the growth of myeloma cells, patient tumor cells and xenotransplants. MiR-29b replacements also decreased PA200 association with proteasomes, reduced the proteasome's peptidase activity and inhibited ornithine decarboxylase turnover, a proteasome substrate degraded through ubiquitin-independent mechanisms. Immunofluorescence studies revealed that miR-29b replacements enhanced the bortezomib-induced accumulation of ubiquitinated proteins but did not reveal aggresome or autophagosome formation. Taken together, our study identifies miR-29b replacements as the first-in-class miR-based PIs that also disrupt the autophagy pathway and highlight their potential to synergistically enhance the antimyeloma effect of bortezomib.
Leukemia 2015 Mar
PMID:MiR-29b replacement inhibits proteasomes and disrupts aggresome+autophagosome formation to enhance the antimyeloma benefit of bortezomib. 2523 65

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