Diamines interfere with the transport of L-ornithine in Ehrlich-cell plasma-membrane vesicles

Pharmacological potential of biogenic amine-polyamine interactions beyond neurotransmission

Histamine, serotonin and dopamine are biogenic amines involved in intercellular communication with multiple effects on human pathophysiology. They are products of two highly homologous enzymes, histidine decarboxylase and l-aromatic amino acid decarboxylase, and transmit their signals through different receptors and signal transduction mechanisms. Polyamines derived from ornithine (putrescine, spermidine and spermine) are mainly involved in intracellular effects related to cell proliferation and death mechanisms. This review summarizes structural and functional evidence for interactions between components of all these amine metabolic and signalling networks (decarboxylases, transporters, oxidases, receptors etc.) at cellular and tissue levels, distinct from nervous and neuroendocrine systems, where the crosstalk among these amine-related components can also have important pathophysiological consequences. The discussion highlights aspects that could help to predict and discuss the effects of intervention strategies.

The polyamine and histamine metabolic interplay in cancer and chronic inflammation

PURPOSE OF REVIEW

To provide an update on the major research contributing to deciphering the metabolic interplay of polyamines/histamine and its impact in cancer and chronic inflammation.

RECENT FINDINGS

The most recent and relevant findings that might reflect a link between the polyamines/histamine metabolic interplay and the development of cancer and chronic inflammation-related diseases include: the observation that histamine catabolism is downregulated in the colonic mucosa of patients with colonic adenoma; the finding that some polyamine and histamine-related metabolites are different between a breast cancer cell line and a reference mammary epithelial cell line; and the demonstration of the critical role that mast cells (a cell type in which the polyamine/histamine metabolic interplay has been confirmed) play in the development of pancreatic tumors. There is still, however, a lack of specific studies elucidating the exact contribution of the polyamine/histamine metabolic interplay in these clinical settings.

SUMMARY

In mammalian cells, a polyamine/histamine metabolic interplay has been extensively proven; however, its ultimate effect on human health largely depends on the cell type and environment. Information on this topic is currently fragmented in the literature. In order to develop efficient intervention strategies, it will be necessary to establish an integrated and holistic view of the role of the polyamine/histamine metabolic interplay in each pathological state.

AMMO-Prot: amine system project 3D-model finder

Background

Amines are biogenic amino acid derivatives, which play pleiotropic and very important yet complex roles in animal physiology. For many other relevant biomolecules, biochemical and molecular data are being accumulated, which need to be integrated in order to be effective in the advance of biological knowledge in the field. For this purpose, a multidisciplinary group has started an ontology-based system named the Amine System Project (ASP) for which amine-related information is the validation bench.

Results

In this paper, we describe the Ontology-Based Mediator developed in the Amine System Project () using the infrastructure of Semantic Directories, and how this system has been used to solve a case related to amine metabolism-related protein structures.

Conclusions

This infrastructure is used to publish and manage not only ontologies and their relationships, but also metadata relating to the resources committed with the ontologies. The system developed is available at .

The usefulness of post-genomics tools for characterization of the amine cross-talk in mammalian cells

Evidence is growing in favour of a relationship between cancer and chronic inflammation, and particularly of the role of a polyamine and histamine metabolic interplay involved in these physiopathological problems, which are indeed highly complex biological systems. Decodification of the complex inter- and intra-cellular signalling mechanisms that control these effects is not an easy task, which must be helped by systems biology technologies, including new tools for location and integration of database-stored information and predictive mathematical models, as well as functional genomics and other experimental molecular approaches necessary for hypothesis validation. We review the state of the art and present our latest efforts in this area, focused on the amine metabolism field.

A comprehensive view of polyamine and histamine metabolism to the light of new technologies

Polyamines and histamine are biogenic amines with multiple biological roles. In spite of the evidence for the involvement of both polyamines and histamine metabolism impairment in several highly prevalent pathological conditions, multiple questions concerning the molecular processes behind these effects remain to be elucidated. More comprehensive and systemic studies integrating molecular biology, biophysical and bioinformatics tools could contribute to accelerate the advances in this research area. This review is designed to underscore the main questions to be answered in polyamine and histamine research and how these new systemic approaches could help to find these answers.

Polyamines are absorbed through a y+ amino acid carrier in rat intestinal epithelial cells

Due to the similarity in transport characteristics of polyamines and the y+ basic amino acid system, we hypothesized that both substrates could be moving through a common carrier site. Competitive and cross inhibition experiments in intestinal epithelial cells revealed the possibility of a common transport site. N-ethylmalemide (NEM) inhibited both lysine and putrescine transport, confirming that both were carried by a y+ transporter. Overexpressing the y+ transporter CAT-1 in a polyamine transport-deficient cell line, CHO-MG, did not reconstitute polyamine-transport. Thus, polyamines are not traveling through CAT-1. To determine if lysine is carried by a polyamine transport site, an antizyme-overexpressing cell line was used. Antizyme overexpression decreased polyamine uptake by 50%; in contrast, lysine transport was unaffected. Therefore, lysine is not traveling through a polyamine transport site. It appears that polyamines and lysine are likely traveling through a common unknown y+ transport site.

Effects of phorbol ester and dexamethasone treatment on histidine decarboxylase and ornithine decarboxylase in basophilic cells

Both histamine and polyamines are important for maintaining basophilic cell function and viability. The synthesis of these biogenic amines is regulated by histidine decarboxylase and ornithine decarboxylase, respectively. In other mammalian tissues, an interplay between histamine and polyamine metabolisms has been suspected. In this report, the interplay between histamine and ornithine-derived polyamines was studied in a non-transformed mouse mast cell line (C57.1) treated with phorbol ester and dexamethasone, a treatment previously used to increase histidine decarboxylase expression in mastocytoma and basophilic leukemia. Treatment with phorbol ester and dexamethasone increased histidine decarboxylase expression and intracellular histamine levels in C57.1 mast cells to a greater extent than those found for other transformed basophilic models. The treatment also induced a reduction in ornithine decarboxylase expression, intracellular polyamine contents, and cell proliferation. These results indicate that the treatment induces a co-ordinate response of polyamine metabolism and proliferation in mast cells and other immune-related cells. The decrease in the proliferative capacity of mast cells caused by phorbol ester and dexamethasone was simultaneous to an increase in histamine production. Our results, together with those reported by other groups working with polyamine-treated mast cells, indicate an antagonism between histamine and polyamines in basophilic cells.

Histamine prevents polyamine accumulation in mouse C57.1 mast cell cultures

The effects of histamine on polyamine uptake and metabolism was studied in a mouse mast cell line (C57.1), as a cell model in which both biogenic amines are important for maintaining cell function and viability. Results obtained after incubations with exogenous histamine indicated that histamine prevents polyamine accumulation by affecting polyamine uptake. A plasma membrane transport system for polyamines has been also studied in mast cells. It seems to be a Na(+)-dependent uptake with high affinity for both spermine and spermidine and lower affinity for putrescine and agmatine. Polyamine uptake was reduced in both cells treated with exogenous histamine and histamine-preloaded cells. However, ornithine decarboxylase activity and cell proliferation were not affected by histamine. Incubation with histamine enhanced the spermidine/spermine acetyl transferase induction caused by N(1)-ethyl-N(11)-[(cyclopropyl)methyl]-4,8-diazaundecane, suggesting that polyamine acetylation could be another mechanism by which histamine prevents polyamine accumulation in C57.1 mast cells.

Agmatine uptake by cultured hamster kidney cells

Agmatine, the product of arginine decarboxylation, has been recently found in a wide variety of animal tissues. In spite of the emergent interest on agmatine in animals, the mechanism of agmatine uptake in mammalian cells has been scarcely studied. An analysis of radiolabeled agmatine uptake was carried out by using a classical, kinetic approach with BHK-21 hamster kidney cells in culture. A high affinity, temperature- and energy-dependent agmatine transport system in BHK-21 kidney cells is here kinetically characterized which seems to be a "general" transporter shared by di- and triamines and different to a highly specific carrier for the tetraamine spermine.

Putrescine and chlorpheniramine inhibit Ehrlich ascites tumor cell plasma membrane ferricyanide reductase activity

The presence of putrescine or chlorpheniramine in the incubation medium of Ehrlich ascites tumor cells starved for 1 h significantly inhibits the rate of ferricyanide reduction by their plasma membrane redox system. Freshly harvested cells, without depletion of their intracellular pools of polyamines, and cells preincubated under conditions arranged to increase ornithine decarboxylase activity also reduced externally added ferricyanide at a lower rate than those cells starved for 1 h. All these data seems to indicate that the presence of putrescine is enough to significantly inhibit Ehrlich cell plasma membrane redox system activity.

Immunonutrition: role of sulfur amino acids, related amino acids, and polyamines

Pro-inflammatory cytokines mediate widespread changes in protein metabolism. Amino acids released from peripheral tissues fulfill a number of functions. They act as substrate for acute phase protein and immunoglobulin synthesis and, together with polyamines, in the replication of immune cells. Demands for specific amino acids may outstrip the supply from endogenous sources. A number of strands of evidence suggest that sulphur amino acids, and amino acids that are metabolically related to them, may be required in increased amounts. Protein deficiency impairs the acute phase response. However, sulfur amino acid insufficiency compromises glutathione synthesis, to a greater extent than hepatic protein synthesis, in the presence and absence of an inflammatory stimulus. The resulting effect may be compromised antioxidant defences. Functioning of T cells is dependent on intracellular glutathione concentrations and may also be affected by sulphur amino acid insufficiency. It has been suggested that the increased N excretion, which occurs during the immune response, is a reflection of a relative imbalance in the profile of amino acids released from peripheral tissues and the requirements imposed by the synthesis of substances involved in the acute phase response. Phenylalanine, tyrosine, tryptophan serine, and cysteine are released in amounts closest to requirements. Polyamine synthesis may be important for the fidelity of the enhanced level DNA transcription and RNA translation that occurs in response to infection and during tissue repair, gut growth after surgery, and in gut barrier functions. Although synthesized de novo from ornithine, arginine and S-adenosyl methionine (SAM), substantial recycling is a key feature of polyamine metabolism. The recycling may be a reflection of the need to maintain adequate tissue SAM during periods of rapid cell growth. During an immune/inflammatory response the combination of enhanced utilization of cysteine for glutathione synthesis and cell replication may lead to depletion of cellular SAM. A relatively small addition of polyamines to the diet may improve gut-associated aspects of the hosts' antibacterial defenses.

Transporters for cationic amino acids in animal cells: discovery, structure, and function

The structure and function of the four cationic amino acid transporters identified in animal cells are discussed. The systems differ in specificity, cation dependence, and physiological role. One of them, system y+, is selective for cationic amino acids, whereas the others (B[0,+], b[0,+], and y+ L) also accept neutral amino acids. In recent years, cDNA clones related to these activities have been isolated. Thus two families of proteins have been identified: 1) CAT or cationic amino acid transporters and 2) BAT or broad-scope transport proteins. In the CAT family, three genes encode for four different isoforms [CAT-1, CAT-2A, CAT-2(B) and CAT-3]; these are approximately 70-kDa proteins with multiple transmembrane segments (12-14), and despite their structural similarity, they differ in tissue distribution, kinetics, and regulatory properties. System y+ is the expression of the activity of CAT transporters. The BAT family includes two isoforms (rBAT and 4F2hc); these are 59- to 78-kDa proteins with one to four membrane-spanning segments, and it has been proposed that these proteins act as transport regulators. The expression of rBAT and 4F2hc induces system b[0,+] and system y+ L activity in Xenopus laevis oocytes, respectively. The roles of these transporters in nutrition, endocrinology, nitric oxide biology, and immunology, as well as in the genetic diseases cystinuria and lysinuric protein intolerance, are reviewed. Experimental strategies, which can be used in the kinetic characterization of coexpressed transporters, are also discussed.

Chlorpheniramine inhibits the synthesis of ornithine decarboxylase and the proliferation of human breast cancer cell lines

Proliferation of both mouse and human breast cancer cells was inhibited by chlorpheniramine (CPA) in a dose-response manner. At the beginning of the exponential phase of growth (two days after seeding), 250 microM CPA was able to reduce cell proliferation by 75% (in Ehrlich cell cultures) and 30% (in MCF-7 cultures). The antiproliferative effect of CPA was also tested on a poorly-differentiated and hormone-insensitive human breast cancer cell line (MDA-MB231) and on a highly proliferative human colon cancer cell line (clone 3). CPA was cytotoxic for MDA-MB231 cells at concentrations higher than 50 microM, and it was also cytotoxic for the colon cancer cell clone 3 at 250 microM CPA. Nevertheless, colon cancer cells were slightly stimulated at CPA concentrations less than 100 microM. CPA reduced (by 50-70%) the ornithine decarboxylase induction occurring early after culture seeding of experimental mammary tumors (Ehrlich carcinoma cells) and human breast cancer cells (MCF-7). The presented data suggest that in addition to ODC inhibition, CPA presents other still unknown cytotoxic effects.

Metabolism of ornithine, alpha-ketoglutarate and arginine in isolated perfused rat liver

Ornithine (Orn; alpha-ketoglutarate (alpha KG) salt) and arginine (Arg) supplementation of enteral diets has been advocated in the treatment of hypercatabolism of trauma patients, but both compounds are subject to extensive hepatic metabolism. To compare the metabolism of these two compounds and to evaluate the possible influence of the alpha KG moiety, livers were perfused with alpha KG, Orn, ornithine alpha-ketoglutarate (OKG) or Arg (n 6 in each group) for 1 h. Arg uptake was nearly fourfold higher than Orn uptake (690 (SD 162) v. 178 (SD 30) nmol/min per g liver), and Orn uptake was not modified by alpha KG. Orn was totally metabolized by the liver, whereas Arg led to Orn release (408 (SD 159) nmol/min per g liver) and a threefold stimulation of urea production (Arg 1.44 (SD 0.22) v. Orn 0.45 (SD 0.09) mumol/min per g liver). alpha KG alone only increased hepatic aspartate uptake but, when associated with Orn as OKG, it led to an increase in glutamate release and in proline content in the liver and to a decrease in proline uptake. From these findings we conclude that (1) Arg load is extensively metabolized by the liver, inducing urea production, (2) in enteral use, Orn supplementation appears preferable to Arg as it is less ureogenic (as also recently demonstrated in vivo in stressed rats receiving isomolar amounts of Arg and Orn), (3) the liver participates in the Orn-alpha KG metabolic interaction, mostly in proline metabolism, which occurs in the splanchnic area.

The induction of ornithine decarboxylase by ornithine takes place at post-transcriptional level in perifused Ehrlich carcinoma cells

The increase in ODC activity during perifusion of Ehrlich carcinoma cells with 0.5 mM ornithine correlates with an increase in 'de novo' synthetized ODC protein. ODC synthesis was followed by immunoprecipitation of equal quantities of 35S-labelled proteins after 10, 20 and 30 min of labelling. In addition, the rate of 'de novo' protein synthesis is very much elevated in cells perifused with saline buffer supplemented with 0.5 mM ornithine than in cells perifused with the saline buffer only. In spite of the higher specific ODC activity observed in cells perifused with saline buffer plus 0.5 mM ornithine respect to cells perifused with only saline buffer for 3.5 h, no elevation in ODC mRNA was observed when the cells were perifused in the presence of 0.5 mM ornithine.