Influence of organic cations on basic amino-acid uptake by human placental villi

Human placental chorionic villi were incubated for 30 min with [3H]lysine or [3H]arginine and the distribution ratios (intracellular:extracellular concentrations) were determined. The ratios remained unchanged when Na+ in Earle's buffered salt solution was replaced with Li+. When Na+ was replaced with choline there was a significant increase is distribution ratios (lysine 1.34 +/- 0.33 v. 3.99 +/- 0.15, arginine 1.95 +/- 0.37 v. 5.05 +/- 1.16). Leucine, a neutral amino acid with a Na(+)-independent transport system, was unaffected by choline substitution. The distribution ratio for alanine, which is Na(+)-dependent, was reduced (2.50 +/- 0.41 v. 1.45 +/- 0.20). Two other quarternary amines, acetyl-beta-methylcholine and tetraethylammonium chloride (TEA) caused similar increases in the distribution ratios of the basic amino acids. Hordenine, a tertiary amine, was less effective and there was little or no effect with ephedrine, a secondary amine. The choline effect was first observable at concentrations of 105 mM. With TEA, there was a progressive increase in distribution ratios beginning at 29 mM. Lysine efflux was measured after incubation of villi with lysine in Earle's buffer or choline buffer. Lysine was rapidly released to the fresh medium with 25% more retained in choline-exposed villi. The amines may cause alterations in the kinetics of basic amino-acid transporters or may modify other aspects of placental physiology permitting an increase retention of the basic amino acids.

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Dicarboxylic Amino Acid Uptake in Normal, Friedreich's Ataxia, and Dicarboxylic Aminoaciduria Fibroblasts

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100119766 ◽

1979 ◽

Vol 6 (2) ◽

pp. 263-273 ◽

Cited By ~ 5

Author(s):

S.B. Melancon ◽

B. Grenier ◽

L. Dallaire ◽

M. Potier ◽

G. Fontaine ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Amino Acid Uptake ◽

Friedreich’S Ataxia ◽

Friedreich's Ataxia ◽

Acid Uptake ◽

Normal Cells ◽

Dicarboxylic Amino Acid ◽

Normal Individuals ◽

Kinetics Of

SummaryGlutamic and aspartic acid uptake was measured in skin fibroblasts from patients with Friedreich's Ataxia, dicarboxylic aminoaciduria, and normal individuals. The results showed no difference in uptake kinetics of either dicarboxylic amino acids between Friedreich's Ataxia and normal cells, but reduced uptake velocities in dicarboxylic aminoaciduria fibroblasts. Friedreich's Ataxia fibroblasts were, however, less calcium-dependant and more magnesium and phosphate-dependent than controls in glucose-free incubation mixture. This difference might be related to some degree of glucose intolerance by Friedreich's Ataxia fibroblasts in culture.

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The role of amino acid transporters in inherited and acquired diseases

Biochemical Journal ◽

10.1042/bj20101912 ◽

2011 ◽

Vol 436 (2) ◽

pp. 193-211 ◽

Cited By ~ 109

Author(s):

Stefan Bröer ◽

Manuel Palacín

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Mammalian Cells ◽

Neuronal Excitability ◽

Tumour Progression ◽

Building Blocks ◽

Amino Acid Uptake ◽

Whole Body ◽

Amino Acid Transporters ◽

Acid Uptake

Amino acids are essential building blocks of all mammalian cells. In addition to their role in protein synthesis, amino acids play an important role as energy fuels, precursors for a variety of metabolites and as signalling molecules. Disorders associated with the malfunction of amino acid transporters reflect the variety of roles that they fulfil in human physiology. Mutations of brain amino acid transporters affect neuronal excitability. Mutations of renal and intestinal amino acid transporters affect whole-body homoeostasis, resulting in malabsorption and renal problems. Amino acid transporters that are integral parts of metabolic pathways reduce the function of these pathways. Finally, amino acid uptake is essential for cell growth, thereby explaining their role in tumour progression. The present review summarizes the involvement of amino acid transporters in these roles as illustrated by diseases resulting from transporter malfunction.

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The tea plant CsLHT1 and CsLHT6 transporters take up amino acids, as a nitrogen source, from the soil of organic tea plantations

Horticulture Research ◽

10.1038/s41438-021-00615-x ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Fang Li ◽

Chunxia Dong ◽

Tianyuan Yang ◽

Shilai Bao ◽

Wanping Fang ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Amino Acid Content ◽

Amino Acid Uptake ◽

Amino Acid Transporters ◽

Acid Uptake ◽

Tea Plantation ◽

Tea Plantations ◽

Organic Tea ◽

Tea Plants

AbstractOrganic tea is more popular than conventional tea that originates from fertilized plants. Amino acids inorganic soils constitute a substantial pool nitrogen (N) available for plants. However, the amino-acid contents in soils of tea plantations and how tea plants take up these amino acids remain largely unknown. In this study, we show that the amino-acid content in the soil of an organic tea plantation is significantly higher than that of a conventional tea plantation. Glutamate, alanine, valine, and leucine were the most abundant amino acids in the soil of this tea plantation. When 15N-glutamate was fed to tea plants, it was efficiently absorbed and significantly increased the contents of other amino acids in the roots. We cloned seven CsLHT genes encoding amino-acid transporters and found that the expression of CsLHT1, CsLHT2, and CsLHT6 in the roots significantly increased upon glutamate feeding. Moreover, the expression of CsLHT1 or CsLHT6 in a yeast amino-acid uptake-defective mutant, 22∆10α, enabled growth on media with amino acids constituting the sole N source. Amino-acid uptake assays indicated that CsLHT1 and CsLHT6 are H+-dependent high- and low-affinity amino-acid transporters, respectively. We further demonstrated that CsLHT1 and CsLHT6 are highly expressed in the roots and are localized to the plasma membrane. Moreover, overexpression of CsLHT1 and CsLHT6 in Arabidopsis significantly improved the uptake of exogenously supplied 15N-glutamate and 15N-glutamine. Taken together, our findings are consistent with the involvement of CsLHT1 and CsLHT6 in amino-acid uptake from the soil, which is particularly important for tea plants grown inorganic tea plantations.

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Kinetics of Uptake of An Amino Acid and a Dipeptide into Hamster Jejunum and Ileum: The Effect of Semistarvation and Starvation

Clinical Science ◽

10.1042/cs0560487 ◽

1979 ◽

Vol 56 (5) ◽

pp. 487-492 ◽

Cited By ~ 9

Author(s):

H. P. Schedl ◽

D. Burston ◽

Elizabeth Taylor ◽

D. M. Matthews

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Unit Length ◽

Amino Acid Uptake ◽

Acid Uptake ◽

Intestinal Uptake ◽

Main Effect ◽

Kinetics Of Uptake ◽

Kinetics Of

1. This paper reports an investigation of the effects of semistarvation and starvation on the kinetics of uptake of an amino acid, l-leucine, and a hydrolysis-resistant dipeptide, Gly-Sar, by rings of everted hamster jejunum and ileum in vitro. The concentration range used was 0·1–100 mmol/l. Total uptake, non-mediated uptake and Kt and Vmax. for mediated influx were estimated. 2. At many concentrations, both semistarvation and starvation caused a decrease in uptake of the peptide and the amino acid. Uptake of the peptide was more severely depressed than that of the amino acid. In control animals, the jejunum was the site of maximal uptake of Gly-Sar, and the ileum the site of maximal uptake of leucine. In semistarved and starved animals, the ileum became the site of maximal uptake of Gly-Sar, as it was for leucine. The effects of semistarvation and starvation on uptake were similar whether this was expressed per unit wt. or per unit length, though they were accentuated when expressed per unit length, since the intestine lost weight per unit length. 3. The main effect of semistarvation and starvation on the kinetics of mediated influx of the amino acid and the peptide was to reduce Vmax. in both jejunum and ileum. This effect was compatible with a reduction in the number of mediated transport sites for both the amino acid and the peptide. The observation that mediated influx of the peptide was more severely affected than that of the amino acid supports the hypothesis of the independence of the mechanisms for intestinal uptake of peptides and amino acids.

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Sequential amino acid measurements during experimental diabetic ketoacidosis

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.228.1.205 ◽

1975 ◽

Vol 228 (1) ◽

pp. 205-211 ◽

Cited By ~ 15

Author(s):

PJ Blackshear ◽

KGMM Alberti

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Whole Blood ◽

Insulin Injection ◽

Amino Acid Uptake ◽

Progressive Increase ◽

Second Phase ◽

Acid Uptake ◽

Male Wistar Rats ◽

Branched Chain

This study was designed to investigate the sequential amino acid response to acute insulin deprivation. Male Wistar rats were made severly diabetic by the intravenous injection of streptozotocin, 150 mg/kg, and maintained on insulin for 7 days. Insulin was then withheld, and measurememts of whole blood and plasma amino acid concentrations were made at 24-h intervals until 120 h, by which time animal mortality was 80%. Alanine and the other gluogenic amino acids displayed a biphasic response to insulin deprivation, decreasing in plasma and whole blood until 72 h after the last insulin injection then increasing in concentration until 120 h. The branched-chain amino acids valine, leucine, and isoleucine remained constant until 72 h after insulin, after which time their concentrations increased dramatically. It was concluded that the first phase represented enhanced gluconeogenesis and in the second phase amino acid uptake for gluconeogenesis was exceeded by net peripheral amino acid release. Enzymatic measurements showed a progressive increase in erythrocyte;plasma distribution ratios for glutamate in ketoacidosis.

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The Regulation and Function of the L-Type Amino Acid Transporter 1 (LAT1) in Cancer

International Journal of Molecular Sciences ◽

10.3390/ijms19082373 ◽

2018 ◽

Vol 19 (8) ◽

pp. 2373 ◽

Cited By ~ 24

Author(s):

Travis Salisbury ◽

Subha Arthur

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Cancer Cells ◽

Amino Acid Uptake ◽

Essential Amino Acids ◽

Amino Acid Transporter ◽

Amino Acid Transporters ◽

Acid Uptake ◽

Cancer Pathways ◽

Acid Transporter

The progression of cancer is associated with increases in amino acid uptake by cancer cells. Upon their entry into cells through specific transporters, exogenous amino acids are used to synthesize proteins, nucleic acids and lipids and to generate ATP. The essential amino acid leucine is also important for maintaining cancer-associated signaling pathways. By upregulating amino acid transporters, cancer cells gain greater access to exogenous amino acids to support chronic proliferation, maintain metabolic pathways, and to enhance certain signal transduction pathways. Suppressing cancer growth by targeting amino acid transporters will require an in-depth understanding of how cancer cells acquire amino acids, in particular, the transporters involved and which cancer pathways are most sensitive to amino acid deprivation. L-Type Amino Acid Transporter 1 (LAT1) mediates the uptake of essential amino acids and its expression is upregulated during the progression of several cancers. We will review the upstream regulators of LAT1 and the downstream effects caused by the overexpression of LAT1 in cancer cells.

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Stimulation of basic amino acid uptake by certain neutral amino acids in isolated intestinal epithelial cells

Biochimica et Biophysica Acta (BBA) - Biomembranes ◽

10.1016/0005-2736(71)90308-7 ◽

1971 ◽

Vol 241 (1) ◽

pp. 102-113 ◽

Cited By ~ 26

Author(s):

Sheldon Reiser ◽

Philip A. Christiansen

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Basic Amino Acid ◽

Amino Acid Uptake ◽

Acid Uptake ◽

Intestinal Epithelial ◽

Neutral Amino Acids ◽

Stimulation Of

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Amino Acid Transporters on the Guard of Cell Genome and Epigenome

Cancers ◽

10.3390/cancers13010125 ◽

2021 ◽

Vol 13 (1) ◽

pp. 125

Author(s):

Uğur Kahya ◽

Ayşe Sedef Köseer ◽

Anna Dubrovska

Keyword(s):

Amino Acid ◽

Cancer Metabolism ◽

Tumor Imaging ◽

Redox Homeostasis ◽

Amino Acid Uptake ◽

Metabolic Reprogramming ◽

Tumor Evolution ◽

Amino Acid Transporters ◽

Acid Uptake ◽

Growth And Survival

Tumorigenesis is driven by metabolic reprogramming. Oncogenic mutations and epigenetic alterations that cause metabolic rewiring may also upregulate the reactive oxygen species (ROS). Precise regulation of the intracellular ROS levels is critical for tumor cell growth and survival. High ROS production leads to the damage of vital macromolecules, such as DNA, proteins, and lipids, causing genomic instability and further tumor evolution. One of the hallmarks of cancer metabolism is deregulated amino acid uptake. In fast-growing tumors, amino acids are not only the source of energy and building intermediates but also critical regulators of redox homeostasis. Amino acid uptake regulates the intracellular glutathione (GSH) levels, endoplasmic reticulum stress, unfolded protein response signaling, mTOR-mediated antioxidant defense, and epigenetic adaptations of tumor cells to oxidative stress. This review summarizes the role of amino acid transporters as the defender of tumor antioxidant system and genome integrity and discusses them as promising therapeutic targets and tumor imaging tools.

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