Differential regulation of polyamine synthesis and transmethylation reactions in methylthioadenosine phosphorylase deficient mammalian cells

SUMMARY Polyamines are small, abundant, aliphatic molecules present in all mammalian cells. Within the context of the cell, they play a myriad of roles, from modulating nucleic acid conformation to promoting cellular proliferation and signaling. In addition, polyamines have emerged as important molecules in virus-host interactions. Many viruses have been shown to require polyamines for one or more aspects of their replication cycle, including DNA and RNA polymerization, nucleic acid packaging, and protein synthesis. Understanding the role of polyamines has become easier with the application of small-molecule inhibitors of polyamine synthesis and the use of interferon-induced regulators of polyamines. Here we review the diverse mechanisms in which viruses require polyamines and investigate blocking polyamine synthesis as a potential broad-spectrum antiviral approach.

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Increased prolyl 4-hydroxylase expression and differential regulation of hypoxia-inducible factors in the aged rat brain

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.90829.2008 ◽

2009 ◽

Vol 297 (1) ◽

pp. R158-R165 ◽

Cited By ~ 30

Author(s):

Obinna I. Ndubuizu ◽

Juan C. Chavez ◽

Joseph C. LaManna

Keyword(s):

Cerebral Cortex ◽

Rat Brain ◽

Mammalian Cells ◽

Target Genes ◽

Differential Regulation ◽

Mrna Levels ◽

Hypoxia Inducible Factors ◽

Aged Rat ◽

Fischer 344 ◽

Fischer 344 Rat

Hypoxia-inducible factors (HIFs) are heterodimeric transcription factors that mediate the adaptive response of mammalian cells and tissues to changes in tissue oxygenation. In the present study, we show an age-dependent decline in cortical HIF-1α accumulation and activation of HIF target genes in response to hypoxia. This inducible response is significantly attenuated in the cerebral cortex of 18-mo-old Fischer 344 rat yet virtually absent in the cerebral cortex of 24-mo-old Fischer 344 rat. This attenuated HIF-1α response had no effect on mRNA upregulation of HIF-independent genes in the aged cortex. We have provided evidence that this absent HIF-1α response is directly correlated with an increase in the expression of the HIF regulatory enzyme, prolyl 4-hydroxylase (PHD). In addition, our study shows that cortical HIF-2α expression in senescent normoxic controls is also significantly greater than that of younger normoxic controls, despite no difference in HIF-2α mRNA levels. The posttranslational regulation of HIF-2α under normoxic conditions seems to be attenuated in the aged rat brain, which is an in vivo demonstration of differential regulation of HIF-1α and HIF-2α.

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Polyamine depletion prevents camptothecin-induced apoptosis by inhibiting the release of cytochromec

AJP Cell Physiology ◽

10.1152/ajpcell.00351.2001 ◽

2002 ◽

Vol 282 (6) ◽

pp. C1290-C1297 ◽

Cited By ~ 46

Author(s):

Qing Yuan ◽

Ramesh M. Ray ◽

Leonard R. Johnson

Keyword(s):

Cytochrome C ◽

Mammalian Cells ◽

Caspase 3 ◽

Intestinal Epithelial ◽

Caspase 9 ◽

Cytochrome C Release ◽

Polyamine Synthesis ◽

Antiapoptotic Proteins ◽

Induced Apoptosis ◽

Rate Limiting

C1297, 2002; 10.1152/ajpcell.00351.2001.We have shown previously that depletion of polyamines delays apoptosis induced by camptothecin in rat intestinal epithelial cells (IEC-6). Mitochondria play an important role in the regulation of apoptosis in mammalian cells because apoptotic signals induce mitochondria to release cytochrome c. The latter interacts with Apaf-1 to activate caspase-9, which in turn activates downstream caspase-3. Bcl-2 family proteins are involved in the regulation of cytochrome c release from mitochondria. In this study, we examined the effects of polyamine depletion on the activation of the caspase cascade, release of cytochrome cfrom mitochondria, and expression and translocation of Bcl-2 family proteins. We inhibited ornithine decarboxylase, the first rate-limiting enzyme in polyamine synthesis, with α-difluoromethylornithine (DFMO) to deplete cells of polyamines. Depletion of polyamines prevented camptothecin-induced release of cytochrome c from mitochondria and decreased the activity of caspase-9 and caspase-3. The mitochondrial membrane potential was not disrupted when cytochrome c was released. Depletion of polyamines decreased translocation of Bax to mitochondria during apoptosis. The expression of antiapoptotic proteins Bcl-xL and Bcl-2 was increased in DFMO-treated cells. Caspase-8 activity and cleavage of Bid were decreased in cells depleted of polyamines. These results suggest that polyamine depletion prevents IEC-6 cells from apoptosis by preventing the translocation of Bax to mitochondria, thus preventing the release of cytochrome c.

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Ornithine decarboxylase activity in embryos depends on temperature of development rather than on the stage of development. Molecular adaptation to temperature changes in poikilothermic animals

Biochemical Journal ◽

10.1042/bj2160597 ◽

1983 ◽

Vol 216 (3) ◽

pp. 597-604 ◽

Cited By ~ 8

Author(s):

A A Neyfakh ◽

K N Yarygin ◽

S I Gorgolyuk

Keyword(s):

Ornithine Decarboxylase ◽

Mammalian Cells ◽

Decarboxylase Activity ◽

Polyamine Synthesis ◽

Temperature Changes ◽

Physiological Limits ◽

Stage Of Development ◽

Key Enzyme ◽

Synthesis And Degradation ◽

Misgurnus Fossilis

The activity of ornithine decarboxylase (ODC) (the key enzyme of polyamine synthesis) in different poikilothermic animals depends on the temperatures at which they were kept just before the enzyme assay. With an increase in temperature (within physiological limits) ODC activity rises 5-25-fold within several hours. With a decrease in temperature it falls at the same rate. This effect, studied on loach (Misgurnus fossilis) embryos in detail, was also shown for embryos, larvae and some adult tissues of many species. It is not, however, observed in homoiothermic animals (chick embryos and mammalian cells), nor in bacteria and plants. Changes in polyamine concentrations follow those in ODC activity, but more slowly and to a lesser extent. It is assumed that modulation of ODC activity changes as a result of its synthesis and degradation. We suggest that the temperature-dependence of ODC activity is a mechanism of adaptation which maintains the optimal cellular concentration of polyamines for each temperature.

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Differential Regulation of Base and Nucleotide Excision Repair in Mammalian Cells

Mechanisms of DNA Damage and Repair ◽

10.1007/978-1-4615-9462-8_17 ◽

1986 ◽

pp. 159-170 ◽

Cited By ~ 4

Author(s):

Klaus Erixon

Keyword(s):

Nucleotide Excision Repair ◽

Mammalian Cells ◽

Excision Repair ◽

Differential Regulation ◽

Nucleotide Excision

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Differential regulation of polo-like kinase 1, 2, 3, and 4 gene expression in mammalian cells and tissues

Oncogene ◽

10.1038/sj.onc.1208219 ◽

2005 ◽

Vol 24 (2) ◽

pp. 260-266 ◽

Cited By ~ 97

Author(s):

Jeffrey A Winkles ◽

Gregory F Alberts

Keyword(s):

Gene Expression ◽

Mammalian Cells ◽

Differential Regulation ◽

Expression In Mammalian Cells

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Methylthioadenosine toxicity and metabolism to methionine in mammalian cells

Biochemical Journal ◽

10.1042/bj2550145 ◽

1988 ◽

Vol 255 (1) ◽

pp. 145-152 ◽

Cited By ~ 9

Author(s):

L Christa ◽

J Kersual ◽

J Augé ◽

J L Pérignon

Keyword(s):

Total Synthesis ◽

Toxic Effect ◽

Mammalian Cells ◽

Resting Cells ◽

Free Medium ◽

Raji Cells ◽

Polyamine Synthesis ◽

Ccl39 Cells ◽

Growth Experiments ◽

Metabolic Cycle

5′-Deoxy-5′-methylthioadenosine, a by-product of polyamine synthesis, can support the growth of Raji cells in a methionine-free medium, but not the growth of CCL39 cells, although these cells are also able to incorporate radiolabelled 5′-deoxy-5′-methylthioadenosine (MeSAdo) into methionine, S-adenosyl-L-methionine (AdoMet) and proteins [Christa, Kersual, Augé & Pérignon (1986) Biochem. Biophys. Res. Commun. 135, 131-138]. We first tested the hypothesis of a toxic effect of MeSAdo in the conditions of growth experiments: we could not demonstrate any toxic effect of MeSAdo on the synthesis of macromolecules, nor any toxicity mediated by polyamines or pyrimidine starvation, and we found that the growth of CCL39 cells was strictly dependent on the supply of exogenous methionine. We then tried to determine whether the ability of CCL39 cells to metabolize MeSAdo to methionine and AdoMet was modulated by the proliferation state of CCL39 cells, which is dependent on the supply of exogenous methionine. Studies of the incorporation of radiolabelled MeSAdo show that: (i) the total synthesis of methionine from MeSAdo is twice as high in subconfluent cells (grown in 100 microM-methionine) as in resting cells (cultured in 0 microM-methionine); (ii) the incorporation into proteins does not parallel the total protein synthesis, and the methionine derived from MeSAdo mostly flows out of the cell; (iii) addition of methionine to resting cells immediately leads to a transient and marked increase in metabolism of MeSAdo to AdoMet, presumably reflecting the rapid replenishment of the AdoMet pool of the cells. Taken together, these results suggest that the methionine derived from MeSAdo is preferentially used to synthesize AdoMet rather than proteins, and that this synthesis of AdoMet depends on the ability of the CCL39 cells to grow, and hence on the supply of exogenous methionine. It is proposed that, in CCL39 cells, the metabolic pathway leading from MeSAdo (a by-product of polyamine synthesis) to methionine and to AdoMet (a precursor of polyamine synthesis) is part of a metabolic cycle the activity of which depends, like polyamine synthesis itself, on cell proliferation.

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Differential regulation of galectin expression/reactivity during wound healing in porcine skin and in cultures of epidermal cells with functional impact on migration

Physiological Research ◽

10.33549/physiolres.931624 ◽

2009 ◽

pp. 873-884

Author(s):

J Klíma ◽

L Lacina ◽

B Dvořánková ◽

D Herrmann ◽

JW Carnwath ◽

...

Keyword(s):

Wound Healing ◽

Mammalian Cells ◽

Human Keratinocytes ◽

Differential Regulation ◽

Epidermal Cells ◽

Porcine Skin ◽

New Information ◽

Galectin 3 ◽

Endogenous Lectins

The glycophenotyping of mammalian cells with plant lectins maps aspects of the glycomic profile and disease-associated alterations. A salient step toward delineating their functional dimension is the detection of endogenous lectins. They can translate sugar-encoded changes into cellular responses. Among them, the members of the lectin family of galectins are emerging regulators of cell adhesion, migration and proliferation. Focusing on galectins-1, -3 and -7, we addressed the issue whether their expression is regulated during wound healing in porcine skin as model. A conspicuous upregulation is detected for galectin-1 in the dermis and a neoexpression in the epidermis, where an increased level of galectin-7 was also found. Applying biotinylated tissue lectins as probes, the signal intensities for accessible binding sites decreased, intimating an interaction of the cell lectin with reactive sites. In contrast, galectin-3 parameters remained rather constant. Of note, epidermal cells in culture also showed an increase in expression/presence of galectin-1, measured on the levels of mRNA and protein, in this case by Western blotting and quantitative immunocytochemistry. Used as matrix, galectin-1 conferred resistance to trypsin treatment to attached human keratinocytes and reduced migration into scratch-wound areas in vitro. This report thus presents new information on endogenous lectins in wound healing and differential regulation among the three tested cases.

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Mammalian cell polyamine homeostasis is altered by the radioprotector WR1065

Biochemical Journal ◽

10.1042/bj3350329 ◽

1998 ◽

Vol 335 (2) ◽

pp. 329-334 ◽

Cited By ~ 14

Author(s):

John L. A. MITCHELL ◽

Jennifer RUPERT ◽

Aviva LEYSER ◽

Gary G. JUDD

Keyword(s):

Ornithine Decarboxylase ◽

Mammalian Cells ◽

Regulatory Protein ◽

Polyamine Metabolism ◽

Intact Cells ◽

Polyamine Synthesis ◽

Radiation Induced ◽

Htc Cells ◽

Low Levels ◽

The Stability

Mammalian cells become more susceptible to radiation-induced death and mutagenesis when restricted in their production of the natural polyamines putrescine, spermidine and spermine. The effects of polyamine deprivation are reversed by N-(2-mercaptoethyl)-1,3-diaminopropane (WR1065), a simple aminothiol that has been extensively studied for its radioprotectant properties. Because this compound and its oxidized derivative WR33278 bear some resemblance to the polyamines, it was hypothesized that radioprotection by WR1065 or its metabolites is derived, at least in part, from their ability to supplement the natural polyamines. To evaluate the ability of these aminothiol compounds to emulate polyamine function in intact cells, rat liver hepatoma (HTC) cells were treated with radioprotective doses of WR1065; the ability of this compound to affect various aspects of normal polyamine metabolism was monitored. Although cellular WR1065 was maintained at levels exceeding those of the polyamines, this aminothiol did not have any polyamine-like effect on the initial polyamine biosynthetic enzyme, ornithine decarboxylase, or on polyamine degradative reactions. On the contrary, treatment with relatively low levels of WR1065 resulted in an unexpected increase in putrescine and spermidine synthesis. WR1065 treatment enhanced the stability, and consequently the activity, of ornithine decarboxylase. This stabilization seems to result from a WR1065-induced delay in the synthesis of antizyme, a critical regulatory protein required in the feedback modulation of polyamine synthesis and transport. The increase in cellular spermidine induced by WR1065 might explain its antimutagenic properties, but is probably not a factor in protection against cell killing by radiation. This is the first evidence that compounds can be designed to control polyamine levels by targeting the activity of the regulatory protein antizyme.

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