Transport of L-tyrosine by B16/F10 melanoma cells: the effect of the intracellular content of other amino acids

1990 ◽  
Vol 97 (3) ◽  
pp. 479-485
Author(s):  
J.R. Jara ◽  
J.H. Martinez-Liarte ◽  
F. Solano ◽  
R. Penafiel
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Initial Rate ◽  
Aromatic Amino Acids ◽  
Melanoma Cells ◽  
Transport Systems ◽  
Specific Amino Acid ◽  
Intracellular Content ◽  
Tyrosine Hydroxylation ◽  
In Cells

The uptake of L-Tyr by B16/F10 malignant melanocytes in culture has been studied. These melanoma cells can either be depleted of amino acids by 1 h preincubation in Hanks' isotonic medium or preloaded with a specific amino acid by 1 h preincubation in the same solution containing 2 mM of the amino acid to be preloaded. By means of these pretreatments, it is shown that the rate of L-Tyr uptake is greatly dependent on the content of other amino acids inside the cells. The L-Tyr uptake is higher in cells preloaded with amino acids transported by the L and ASC systems than in cells depleted of amino acids or preloaded with amino acids transported by the A system. It is concluded that L-Tyr is mainly taken up by an exchange mechanism with other amino acids mediated by the L1 system, although the ASC system can also participate in the process. In agreement with that, the homo-exchange performed by cells preloaded with unlabelled L-Tyr is more efficient than any other hetero-exchange, although L-Dopa, the product of tyrosine hydroxylation in melanin synthesis, is almost as efficient as L-Tyr. Apart from aromatic amino acids, melanoma cells preloaded with L-Met and L-His also yield a high initial rate of L-Tyr uptake. The results herein suggest that melanoma cells do not have transport systems specific for L-Tyr, even if this amino acid is needed to carry out the differential pathway of this type of cells, melanosynthesis.

Fluxes and membrane transport of amino acids in rat liver under different protein diets

1990 ◽  
Vol 259 (5) ◽  
pp. E614-E625 ◽  
Author(s):  
P. Fafournoux ◽  
C. Remesy ◽  
C. Demigne
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acids ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Transport Systems ◽  
Low Concentrations ◽  
Significant Uptake

The aim of the present work was to evaluate in vivo the role of the transport step in hepatic amino acid metabolism. To vary hepatic utilization of amino acids, rats were adapted to diets containing various concentrations of casein (5, 15, and 60%). In rats fed 5 or 15% casein diets, Gln and Glu were released by the liver, and there was a significant uptake of Ala. Hepatic fluxes of amino acids increased considerably after adaptation to high-casein diet (up to 1.55 mumol.min-1.g liver-1 for Ala), because of the rise in afferent concentrations as well as enhanced uptake percentage (peaking at 60–75% for most glucogenic amino acids). Adaptation to a high-protein diet led to induction of not only system A but also of most of the other transport systems (Gly, anionic, T, y+, and to a lesser extent system N); only systems ASC and L were unchanged. The study of amino acid repartition between liver and plasma with different diets indicates that transport could modulate utilization of Ala, Ser, Thr, Gly, Gln, and Asp. For Arg and Asn, present in very low concentrations in liver under any condition, the transport step should be the major locus of control of their metabolism. For amino acids chiefly transported by nonconcentrative systems, such as aromatic amino acids, cellular metabolism could also be limited by the transport process. In conclusion, during adaptation to a high-protein diet, there is apparently a coordinated adaptation of amino acid transport and of their intracellular metabolism. For some amino acids, induction of catabolic enzymes seems greater than that of transport, so that the transport step may play an important role in control of metabolic fluxes. For example, concentration of amino acids such as Thr may be markedly depressed in rats adapted to a high-protein diet.

scholarly journals Ammonium-Dependent Shortening of CLS in Yeast Cells Starved for Essential Amino Acids Is Determined by the Specific Amino Acid Deprived, through Different Signaling Pathways

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Júlia Santos ◽  
Cecília Leão ◽  
Maria João Sousa
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Essential Amino Acid ◽  
Essential Amino Acids ◽  
Amino Acid Starvation ◽  
Yeast Cells ◽  
Environmental Interventions ◽  
Specific Amino Acid ◽  
Chronological Life Span ◽  
In Cells

Ammonium (NH4+) leads to chronological life span (CLS) shortening inSaccharomyces cerevisiaeBY4742 cells, particularly evident in cells starved for auxotrophy-complementing amino acids (leucine, lysine, and histidine) simultaneously. Here, we report that the effect ofNH4+on aging yeast depends on the specific amino acid they are deprived of. Compared with no amino acid starvation, starvation for leucine alone or in combination with histidine resulted in the most pronouncedNH4+-induced CLS shortening, whereas starvation for lysine, alone or in combination with histidine resulted in the least sensitivity toNH4+. We also show thatNH4+-induced CLS shortening is mainly mediated by Tor1p in cells starved for leucine or histidine but by Ras2p in cells starved for lysine, and in nonstarved cells. Sch9p protected cells from the effect ofNH4+under all conditions tested (starved or nonstarved cells), which was associated with Sch9p-dependent Hog1p phosphorylation. Our data show thatNH4+toxicity can be modulated through manipulation of the specific essential amino acid supplied to cells and of the conserved Ras2p, Tor1p, and Sch9p regulators, thus providing new clues to the development of environmental interventions for CLS extension and to the identification of new therapeutic targets for diseases associated with hyperammonemia.

scholarly journals Transport of the aromatic amino acids into isolated rat liver cells. Properties of uptake by two distinct systems

1986 ◽  
Vol 233 (2) ◽  
pp. 499-506 ◽  
Author(s):  
M Salter ◽  
R G Knowles ◽  
C I Pogson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Liver ◽  
Transport System ◽  
Aromatic Amino Acids ◽  
Liver Cells ◽  
Transport Systems ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Isolated Rat

The transport of the aromatic amino acids into isolated rat liver cells was studied. There was a rapid and substantial binding of the aromatic amino acids, L-alanine and L-leucine to the plasma membrane. This has important consequences for the determination of rates of transport and intracellular concentrations of the amino acids. Inhibition studies with a variety of substrates of various transport systems gave results consistent with aromatic amino acid transport being catalysed by two systems: a 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH)-insensitive aromatic D- and L-amino acid-specific system, and the L-type system (BCH-sensitive). The BCH-insensitive component of transport was Na+-independent and facilitated non-concentrative transport of the aromatic amino acids; it was unaffected by culture of liver cells for 24 h, by 48 h starvation, dexamethasone phosphate or glucagon. Kinetic properties of the BCH-inhibitable component were similar to those previously reported for the L2-system in liver cells. The BCH-insensitive component was a comparatively low-Km low-Vmax. transport system that we suggest is similar to the T-transport system previously seen only in human red blood cells. The results are discussed with reference to the importance of the T- and L-systems in the control of aromatic L-amino acid degradation in the liver.

Single Amino Acid Based Self-Assemblies of Cysteine and Methionine

2018 ◽  
Author(s):  
Nidhi Gour ◽  
Bharti Koshti ◽  
Chandra Kanth P. ◽  
Dhruvi Shah ◽  
Vivek Shinh Kshatriya ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Self Assembly ◽  
Aromatic Amino Acids ◽  
Neutral Condition ◽  
Single Amino Acid ◽  
Binding Assays ◽  
Human Neuroblastoma ◽  
Cytotoxicity Assays ◽  
First Time

We report for the very first time self-assembly of Cysteine and Methionine to discrenible strucutres under neutral condition. To get insights into the structure formation, thioflavin T and Congo red binding assays were done which revealed that aggregates may not have amyloid like characteristics. The nature of interactions which lead to such self-assemblies was purported by coincubating assemblies in urea and mercaptoethanol. Further interaction of aggregates with short amyloidogenic dipeptide diphenylalanine (FF) was assessed. While cysteine aggregates completely disrupted FF fibres, methionine albeit triggered fibrillation. The cytotoxicity assays of cysteine and methionine structures were performed on Human Neuroblastoma IMR-32 cells which suggested that aggregates are not cytotoxic in nature and thus, may not have amyloid like etiology. The results presented in the manuscript are striking, since to the best of our knowledge,this is the first report which demonstrates that even non-aromatic amino acids (cysteine and methionine) can undergo spontaneous self-assembly to form ordered aggregates.

Characterization of an isozyme of S-adenosylmethionine synthetase from rat liver

1984 ◽  
Vol 62 (5) ◽  
pp. 276-279 ◽  
Author(s):  
C. H. Lin ◽  
W. Chung ◽  
K. P. Strickland ◽  
A. J. Hudson
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Enzymatic Synthesis ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Aromatic Amino Acids ◽  
Adenosylmethionine Synthetase ◽  
Cellulose Column

An isozyme of S-adenosylmethionine synthetase has been purified to homogeneity by ammonium sulfate fractionation, DEAE-cellulose column chromatography, and gel filtration on a Sephadex G-200 column. The purified enzyme is very unstable and has a molecular weight of 120 000 consisting of two identical subunits. Amino acid analysis on the purified enzyme showed glycine, glutamate, and aspartate to be the most abundant and the aromatic amino acids to be the least abundant. It possesses tripolyphosphatase activity which can be stimulated five to six times by S-adenosylmethionine (20–40 μM). The findings support the conclusion that an enzyme-bound tripolyphosphate is an obligatory intermediate in the enzymatic synthesis of S-adenosylmethionine from ATP and methionine.

Amino Acid Transport in a Water-mould: The Possible Regulatory Roles of Calcium and N6-(Δ2-isopentenyl)adenine

1975 ◽  
Vol 53 (9) ◽  
pp. 975-988 ◽  
Author(s):  
Danny P. Singh ◽  
Hérb. B. LéJohn
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Osmotic Shock ◽  
Inhibitory Effect ◽  
Transport Systems ◽  
Acid Transport ◽  
Isopentenyl Adenine ◽  
Energy Dependent ◽  
Water Mould

Transport of amino acids in the water-mould Achlya is an energy-dependent process. Based on competition kinetics and studies involving the influence of pH and temperature on the initial transport rates, it was concluded that the 20 amino acids (L-isomers) commonly found in proteins were transported by more than one, possibly nine, uptake systems. This is similar to the pattern elucidated for some bacteria but unlike those uncovered for all fungi studied to date. The nine different transport systems elucidated are: (i) methionine, (ii) cysteine, (iii) proline, (iv) serine–threonine, (v) aspartic and glutamic acids, (vi) glutamine and asparagine, (vii) glycine and alanine, (viii) histidine, lysine, and arginine, and (ix) phenylalanine–tyrosine–tryptophan and leucine–isoleucine–valine as two overlapping groups. Transport of all of these amino acids was inhibited by azide, cyanide, and its derivatives and 2,4-dinitrophenol. These agents normally interfere with metabolism at the level of the electron transport chain and oxidative phosphorylation. Osmotic shock treatment of the cells released, into the shock fluid, a glycopeptide that binds calcium as well as tryptophan but no other amino acid. The shocked cells are incapable of concentrating amino acids, but remain viable and reacquire this capacity when the glycopeptide is resynthesized.Calcium played more than a secondary role in the transport of the amino acids. When bound to the membrane-localized glycopeptide, it permits concentrative transport to take place. However, excess calcium can inhibit transport which can be overcome by chelating with citrate. Calculations show that the concentration of free citrate is most important. At low citrate concentrations (less than 1 mM) in the absence of exogenously supplied calcium, enhancement of amino acid transport occurs. At high concentrations (greater than 5 mM), citrate inhibits but this effect can be reversed by titrating with calcium. Evidently, the glycopeptide acts as a calcium sink to regulate the concentration of calcium made available to the cell for its membrane activities.N6-(Δ2-isopentenyl) adenine (a plant growth 'hormone') and analogues mimic the inhibitory effect of citrate and bind to the glycopeptide as well. Replot data for citrate and N6-(Δ2-isopentyl) adenine inhibition indicate that both agents have no more than one binding constant. These results implicate calcium, glycopeptide, and energy-dependent transport of solutes in some, as yet undefinable, way.

Placental amino acid transport

1995 ◽  
Vol 268 (6) ◽  
pp. C1321-C1331 ◽  
Author(s):  
A. J. Moe
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Human Placenta ◽  
Amino Acid Transport ◽  
Single Layer ◽  
Maternal Blood ◽  
Transport Systems ◽  
Amino Acid Transporters ◽  
Acid Transport ◽  
Principal Mechanism

Normal fetal growth and development depend on a continuous supply of amino acids from the mother to the fetus. The placenta is responsible for the transfer of amino acids between the two circulations. The human placenta is hemomonochorial, meaning that the maternal and fetal circulations are separated by a single layer of polarized epithelium called the syncytiotrophoblast, which is in direct contact with maternal blood. Transport proteins located in the microvillous and basal membranes of the syncytiotrophoblast are the principal mechanism for transfer from maternal blood to fetal blood. Knowledge of the function and regulation of syncytiotrophoblast amino acid transporters is of great importance in understanding the mechanism of placental transport and potentially improving fetal and newborn outcomes. The development of methods for the isolation of microvillous and basal membrane vesicles from human placenta over the past two decades has contributed greatly to this understanding. Now a primary cultured trophoblast model is available to study amino acid transport and regulation as the cells differentiate. The types of amino acid transporters and their distribution between the syncytiotrophoblast microvillous and basal membranes are somewhat unique compared with other polarized epithelia. These differences may reflect the unusual circumstance of this epithelium that is exposed to blood on both sides. The current state of knowledge as to the types of transport systems present in syncytiotrophoblast, their regulation, and the effects of maternal consumption of drugs on transport are discussed.

Multiple pathways for cationic amino acid transport in rat thyroid epithelial cell line PC Cl3

2005 ◽  
Vol 288 (2) ◽  
pp. C290-C303 ◽  
Author(s):  
Tiziano Verri ◽  
Cinzia Dimitri ◽  
Sonia Treglia ◽  
Fabio Storelli ◽  
Stefania De Micheli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cell Line ◽  
Amino Acid Transport ◽  
Transport Systems ◽  
Residual Fraction ◽  
Acid Transport ◽  
Thyroid Cells ◽  
Cationic Amino Acid ◽  
Rat Thyroid

Information regarding cationic amino acid transport systems in thyroid is limited to Northern blot detection of y+LAT1 mRNA in the mouse. This study investigated cationic amino acid transport in PC cell line clone 3 (PC Cl3 cells), a thyroid follicular cell line derived from a normal Fisher rat retaining many features of normal differentiated follicular thyroid cells. We provide evidence that in PC Cl3 cells plasmalemmal transport of cationic amino acids is Na+ independent and occurs, besides diffusion, with the contribution of high-affinity, carrier-mediated processes. Carrier-mediated transport is via y+, y+L, and b0,+ systems, as assessed by l-arginine uptake and kinetics, inhibition of l-arginine transport by N-ethylmaleimide and neutral amino acids, and l-cystine transport studies. y+L and y+ systems account for the highest transport rate (with y+L > y+) and b0,+ for a residual fraction of the transport. Uptake data correlate to expression of the genes encoding for CAT-1, CAT-2B, 4F2hc, y+LAT1, y+LAT2, rBAT, and b0,+AT, an expression profile that is also shown by the rat thyroid gland. In PC Cl3 cells cationic amino acid uptake is under TSH and/or cAMP control (with transport increasing with increasing TSH concentration), and upregulation of CAT-1, CAT-2B, 4F2hc/y+LAT1, and rBAT/b0,+AT occurs at the mRNA level under TSH stimulation. Our results provide the first description of an expression pattern of cationic amino acid transport systems in thyroid cells. Furthermore, we provide evidence that extracellular l-arginine is a crucial requirement for normal PC Cl3 cell growth and that long-term l-arginine deprivation negatively influences CAT-2B expression, as it correlates to reduction of CAT-2B mRNA levels.

scholarly journals Involvement of calcium-sensing receptor activation in the alleviation of intestinal inflammation in a piglet model by dietary aromatic amino acid supplementation

2018 ◽  
Vol 120 (12) ◽  
pp. 1321-1331 ◽  
Author(s):  
Hongnan Liu ◽  
Bie Tan ◽  
Bo Huang ◽  
Jianjun Li ◽  
Jing Wang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Inflammatory Cytokines ◽  
Intestinal Inflammation ◽  
Aromatic Amino Acids ◽  
Dietary Supplementation ◽  
Basal Diet ◽  
Signalling Pathway ◽  
Protein Levels ◽  
Pro Inflammatory Cytokines

AbstractCa2+-sensing receptor (CaSR) represents a potential therapeutic target for inflammatory bowel diseases and strongly prefers aromatic amino acid ligands. We investigated the regulatory effects of dietary supplementation with aromatic amino acids – tryptophan, phenylalanine and tyrosine (TPT) – on the CaSR signalling pathway and intestinal inflammatory response. The in vivo study was conducted with weanling piglets using a 2 × 2 factorial arrangement in a randomised complete block design. Piglets were fed a basal diet or a basal diet supplemented with TPT and with or without inflammatory challenge. The in vitro study was performed in porcine intestinal epithelial cell line to investigate the effects of TPT on inflammatory response using NPS-2143 to inhibit CaSR. Dietary supplementation of TPT alleviated histopathological injury and decreased myeloperoxidase activity in intestine challenged with lipopolysaccharide. Dietary supplementation of TPT decreased serum concentration of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12, granulocyte-macrophage colony-stimulating factor, TNF-α), as well as the mRNA abundances of pro-inflammatory cytokines in intestine but enhanced anti-inflammatory cytokines IL-4 and transforming growth factor-β mRNA levels compared with pigs fed control diet and infected by lipopolysaccharide. Supplementation of TPT increased CaSR and phospholipase Cβ2 protein levels, but decreased inhibitor of NF-κB kinase α/β and inhibitor of NF-κB (IκB) protein levels in the lipopolysaccharide-challenged piglets. When the CaSR signalling pathway was blocked by NPS-2143, supplementation of TPT decreased the CaSR protein level, but enhanced phosphorylated NF-κB and IκB levels in IPEC-J2 cells. To conclude, supplementation of aromatic amino acids alleviated intestinal inflammation as mediated through the CaSR signalling pathway.

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