Identification of a high affinity taurine transporter which is not dependent on chloride

1995 ◽  
Vol 15 (4) ◽  
pp. 231-239 ◽  
Author(s):  
D. B. Shennan
Keyword(s):  
Amino Acids ◽  
Transport System ◽  
Niflumic Acid ◽  
Cell Swelling ◽  
Mammary Tissue ◽  
Taurine Transporter ◽  
Taurine Transport ◽  
High Affinity ◽  
Taurine Uptake

Taurine transport by lactating gerbil mammary tissue has been examined. Taurine uptake is, mediated by a high-affinity system which is specific for β-amino acids. The uptake of taurine is Na+-dependent but appears not to be obligatorly dependent upon Cl−. Thus, replacing Na+ with choline almost abolished taurine uptake. Substituting Cl− with NO3− had no effect whereas SCN− induced a small but significant increase in taurine influx. Taurine uptake was Na+-dependent under conditions where Cl− had been replaced with NO3−. However, it is apparent that the Na+-dependent taurine transport system requires the presence of a permeable anion because replacing Cl− with gluconate markedly reduced taurine uptake. Cell-swelling, induced by a hyposmotic challenge, increased the efflux of taurine from gerbil mammary tissue via a pathway sensitive to niflumic acid.

High affinity (Na+ + Cl-)-dependent taurine transport by lactating mammary tissue

1994 ◽  
Vol 61 (3) ◽  
pp. 335-343 ◽  
Author(s):  
David B. Shennan ◽  
Sandra A. McNeillie
Keyword(s):  
Apical Membrane ◽  
Slow Component ◽  
Mammary Tissue ◽  
Cell Water ◽  
Simple Diffusion ◽  
Taurine Transport ◽  
High Affinity ◽  
Cell Cytosol ◽  
High Level ◽  
Taurine Uptake

SummaryThe transport of taurine by lactating rat mammary tissue has been examined. Taurine uptake was found to be dependent upon the presence of extracellular Na+ and Cl-, which is consistent with (Na+ + Cl- + taurine) cotransport. The Ka and Vmax of taurine influx were respectively 43 μM and 37·5 μmol/kg cell water per 15 min. It is apparent that the mechanism responsible for taurine uptake is highly selective for β-amino acids. Taurine efflux consisted of a fast extracellular component and a slow membrane-limited component. The slow component was relatively insensitive to temperature, suggesting that it may represent simple diffusion. Mammary tissue was found to contain a high level of intracellular taurine: 7·29–7·44 mmol/kg cell water. We suggest that taurine is taken up and concentrated by the mammary gland by a (Na+ + Cl- + taurine) cotransport mechanism situated in the blood-facing aspect of the secretory epithelium and that a low outward permeability to taurine allows a high intra-to-extracellular concentration gradient to be maintained. Milk taurine may be derived from taurine diffusing from the cell cytosol across the apical membrane.

Ionic requirements of peritubular taurine transport in Fundulus kidney

1986 ◽  
Vol 250 (6) ◽  
pp. R984-R990 ◽  
Author(s):  
N. A. Wolff ◽  
D. F. Perlman ◽  
L. Goldstein
Keyword(s):  
Amino Acids ◽  
Transport System ◽  
Fundulus Heteroclitus ◽  
The Other ◽  
Renal Tubules ◽  
Taurine Transport ◽  
System A ◽  
Absolute Requirement ◽  
Relationship Of ◽  
Taurine Uptake

A peritubular mechanism for active taurine uptake, similar to that previously found in the flounder, was demonstrated in killifish (Fundulus heteroclitus) teased renal tubules. Other beta-amino acids and glycine inhibited taurine transport. Uptake exhibited a nearly absolute requirement for external Na+. The stoichiometric relationship between Na+ and taurine was found to be 2:1. Medium Cl- markedly stimulated the Na+-dependent taurine uptake, but none of the other small monovalent anions tested (NO3-, Br-, SCN-) could substitute for Cl- in activating taurine transport. Cl- replacement resulted in a significant decrease in V max, whereas the affinity of the carrier for taurine appeared to be unaffected. In the absence of Cl- the Na+ dependence of taurine influx was reduced to a stoichiometric relationship of 1.4 Na+:1 taurine, indicating an effect of Cl- on the binding of Na+ to the transport system. A model for Na+ -Cl- -taurine cotransport is presented.

scholarly journals Transport of taurine and its regulation by protein kinase C in the JAR human placental choriocarcinoma cell line

1991 ◽  
Vol 277 (1) ◽  
pp. 53-58 ◽  
Author(s):  
P Kulanthaivel ◽  
D R Cool ◽  
S Ramamoorthy ◽  
V B Mahesh ◽  
F H Leibach ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Line ◽  
Transport System ◽  
Taurine Transporter ◽  
Taurine Transport ◽  
Kinase C ◽  
Choriocarcinoma Cells ◽  
Choriocarcinoma Cell Line

The JAR human placental choriocarcinoma cell line transports taurine, concentrating it over 1000-fold inside the cell. The transport system is energized by a Na+ gradient and exhibits an absolute requirement for Cl-. Neutral beta-amino acids such as beta-alanine and hypotaurine effectively compete with the system, whereas neutral alpha-amino acids such as alanine, leucine and alpha-aminoisobutyric acid do not. The transport system interacts with gamma-aminobutyric acid to an appreciable extent. Kinetic analysis reveals that the taurine transport system in this cell line is of a high-affinity and low-capacity type (apparent dissociation constant 2.3 +/- 0.3 microM; maximal velocity 88.5 +/- 5.0 pmol/3 min per mg of protein). Pretreatment of the JAR choriocarcinoma cells with phorbol 12-myristate 13-acetate results in the inhibition of the taurine transport system in a dose-dependent manner. The inhibition is blocked by co-treatment of the cells with staurosporine, an inhibitor of protein kinase C. The inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate, has no effect on the transport system. These data show that the choriocarcinoma cells express a taurine transporter with characteristics similar to those of the taurine transporter described in the normal human placenta, and that the activity of the transporter in these cells is under the regulatory control of protein kinase C.

Production of free glutamate in milk requires the leucine transporter LAT1

2013 ◽  
Vol 305 (6) ◽  
pp. C623-C631 ◽  
Author(s):  
Takuya Matsumoto ◽  
Eiji Nakamura ◽  
Hidehiro Nakamura ◽  
Mariko Hirota ◽  
Ana San Gabriel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Transport System ◽  
Active Role ◽  
Mammary Tissue ◽  
Limiting Factor ◽  
Mammary Cells ◽  
Oral Gavage ◽  
Uptake Inhibition ◽  
Umami Taste

The concentration of free glutamate (Glu) in rat's milk is ∼10 times higher than that in plasma. Previous work has shown that mammary tissue actively transports circulatory leucine (Leu), which is transaminated to synthesize other amino acids such as Glu and aspartate (Asp). To investigate the molecular basis of Leu transport and its conversion into Glu in the mammary gland, we characterized the expression of Leu transporters and [3H]Leu uptake in rat mammary cells. Gene expression analysis indicated that mammary cells express two Leu transporters, LAT1 and LAT2, with LAT1 being more abundant than LAT2. This transport system is sodium independent and transports large neutral amino acids. The Leu transport system in isolated rat mammary cells could be specifically blocked by the LAT1 inhibitors 2-aminobicyclo-[2.2.1]-heptane-2-carboxylic acid (BCH) and triiodothyronine (T3). In organ cultures, Glu secretion was markedly inhibited by these LAT1 inhibitors. Furthermore, the profiles of Leu uptake inhibition by amino acids in mammary cells were similar to those reported for LAT1. In vivo, concentrations of free Glu and Asp increased in milk by oral gavage with Leu at 6, 12, and 18 days of lactation. These results indicate that the main Leu transporter in mammary tissue is LAT1 and the transport of Leu is a limiting factor for the synthesis and release of Glu and Asp into milk. Our studies provide the bases for the molecular mechanism of Leu transport in mammary tissue by LAT1 and its active role on free Glu secretion in milk, which confer umami taste in suckling pups.

scholarly journals Osmoregulated taurine transport in H4IIE hepatoma cells and perfused rat liver

1997 ◽  
Vol 321 (3) ◽  
pp. 683-690 ◽  
Author(s):  
Ulrich WARSKULAT ◽  
Matthias WETTSTEIN ◽  
Dieter HÄUSSINGER
Keyword(s):  
Rat Liver ◽  
Hepatoma Cells ◽  
Cell Swelling ◽  
Mrna Levels ◽  
Taurine Transport ◽  
H4iie Cells ◽  
Taurine Uptake ◽  
Rat Hepatoma ◽  
Taurine Efflux ◽  
Rat Hepatoma Cells

The effects of aniso-osmotic exposure on taurine transport were studied in H4IIE rat hepatoma cells. Hyperosmotic (405 mosmol/l) exposure of H4IIE cells stimulated Na+-dependent taurine uptake and led to an increase in taurine transporter (TAUT) mRNA levels, whereas hypo-osmotic (205 mosmol/l) exposure diminished both taurine uptake and TAUT mRNA levels when compared with normo-osmotic (305 mosmol/l) control incubations. Taurine uptake increased 30Ő40-fold upon raising the ambient osmolarity from 205 to 405 mosmol/l. When H4IIE cells and perfused livers were preloaded with taurine, hypo-osmotic cell swelling led to a rapid release of taurine from the cells. The taurine efflux, but not taurine uptake, was sensitive to 4,4ƀ-di-isothiocyanatostilbene-2,2ƀ-disulphonic acid (DIDS), suggestive of an involvement of DIDS-sensitive channels in mediating volume-regulatory taurine efflux. Whereas in both H4IIE rat hepatoma cells and primary hepatocytes TAUT mRNA levels were strongly dependent upon ambient osmolarity, mRNAs for other osmolyte transporters, i.e. the betaine transporter BGT-1 and the Na+/myo-inositol transporter SMIT, were not detectable. In line with this, myo-inositol uptake by H4IIE hepatoma cells was low and was not stimulated by hyperosmolarity. However, despite the absence of BGT-1 mRNA, a slight osmosensitive uptake of betaine was observed, but the rate was less than 10% of that of taurine transport. This study identifies a constitutively expressed and osmosensitive TAUT in H4IIE cells and the use of taurine as a main osmolyte, whereas betaine and myo-inositol play little or no role in the osmolyte strategy in these cells. This is in contrast with rat liver macrophages, in which betaine has been shown to be a major osmolyte.

scholarly journals Involvement of TauT/SLC6A6 in Taurine Transport at the Blood–Testis Barrier

Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 66
Author(s):  
Yoshiyuki Kubo ◽  
Sakiko Ishizuka ◽  
Takeru Ito ◽  
Daisuke Yoneyama ◽  
Shin-ichi Akanuma ◽  
...  
Keyword(s):  
Aminobutyric Acid ◽  
Seminiferous Tubules ◽  
Taurine Transporter ◽  
Taurine Transport ◽  
Plot Analysis ◽  
Influx Transport ◽  
Dependent Inhibition ◽  
Taurine Uptake ◽  
Sertoli Cell Line ◽  
Blood Testis Barrier

Taurine transport was investigated at the blood–testis barrier (BTB) formed by Sertoli cells. An integration plot analysis of mice showed the apparent influx permeability clearance of [3H]taurine (27.7 μL/(min·g testis)), which was much higher than that of a non-permeable paracellular marker, suggesting blood-to-testis transport of taurine, which may involve a facilitative taurine transport system at the BTB. A mouse Sertoli cell line, TM4 cells, showed temperature- and concentration-dependent [3H]taurine uptake with a Km of 13.5 μM, suggesting that the influx transport of taurine at the BTB involves a carrier-mediated process. [3H]Taurine uptake by TM4 cells was significantly reduced by the substrates of taurine transporter (TauT/SLC6A6), such as β-alanine, hypotaurine, γ-aminobutyric acid (GABA), and guanidinoacetic acid (GAA), with no significant effect shown by L-alanine, probenecid, and L-leucine. In addition, the concentration-dependent inhibition of [3H]taurine uptake revealed an IC50 of 378 μM for GABA. Protein expression of TauT in the testis, seminiferous tubules, and TM4 cells was confirmed by Western blot analysis and immunohistochemistry by means of anti-TauT antibodies, and knockdown of TauT showed significantly decreased [3H]taurine uptake by TM4 cells. These results suggest the involvement of TauT in the transport of taurine at the BTB.

scholarly journals Regulation of taurine transporter activity in LLC-PK1 cells: role of protein synthesis and protein kinase C activation.

1991 ◽  
Vol 2 (5) ◽  
pp. 1021-1029 ◽  
Author(s):  
D P Jones ◽  
L A Miller ◽  
C Dowling ◽  
R W Chesney
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Free Medium ◽  
Taurine Transporter ◽  
Taurine Transport ◽  
Kinase C ◽  
Taurine Uptake ◽  
Protein Kinase C Activation

Taurine transporter activity increases after exposure of cultured renal epithelial cells to taurine-free medium for 24 h and decreases after incubation in high (500 microM) taurine. This adaptive response mimics that observed in rat kidney after manipulation of dietary taurine. In order to elucidate potential mechanisms involved in the regulation of beta-amino acid transporter activity, the role of RNA transcription, protein synthesis, and protein import (trafficking), as well as protein kinase C activation, on the control of taurine transport was examined in the continuous proximally derived LLC-PK1 renal cell line. Inhibition of RNA transcription with actinomycin D did not alter the up-regulatory and down-regulatory adaptive responses. Inhibition of protein synthesis with cycloheximide prevented the increased taurine transport in response to taurine-free medium as well as the decrease in taurine transport after exposure to high taurine. Colchicine prevented the response to taurine-free medium but had no effect on the response to high-taurine medium. Exposure of confluent cell monolayers to the active phorbol esters, phorbol 12-myristate 13-acetate and phorbol 12,13 dibutyrate, resulted in a reduction in taurine uptake. The effect was seen within minutes of exposure but was not observed in the presence of the inactive phorbol 4-alpha. This inhibitory action was blocked by staurosporin, an inhibitor of protein kinase C (PKC). Treatment of cells with the diacylglycerol kinase inhibitor R59022, which results in increased intracellular diacylglycerol, a natural stimulant of PKC, also inhibited taurine uptake, providing further evidence for a specific effect of PKC activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogenesis of intestinal taurine transport: evidence for a beta-carrier in developing rat jejunum

1988 ◽  
Vol 254 (6) ◽  
pp. G870-G877 ◽  
Author(s):  
M. S. Moyer ◽  
A. L. Goodrich ◽  
M. M. Rolfes ◽  
F. J. Suchy
Keyword(s):  
Amino Acids ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Equilibrium Concentration ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Rat Jejunum ◽  
Adult Rats ◽  
Taurine Transport ◽  
Taurine Uptake

Taurine, a sulfur-containing beta-amino acid, may be conditionally essential during development. However, the existence of a carrier system for beta-amino acids has not been demonstrated in brush-border membrane vesicles (BBMV) from adult rat jejunum. We studied the uptake of [3H]taurine in BBMV prepared from the jejunum of developing and adult rats using a cation-precipitation technique. Uptake of 10 microM [3H]taurine by adult BBMV was slightly enhanced in the presence of an inwardly directed 100 mM Na+ gradient compared with a K+ gradient, and there was no intravesicular accumulation of isotope above the equilibrium concentration ("overshoot"). In contrast, taurine transport by BBMV from 10-day-old rat pups was markedly accelerated in the presence of a Na+ gradient compared with a K+ gradient and a twofold overshoot was observed. Na+-dependent taurine uptake was inhibited by the structural analogues hypotaurine and beta-alanine but not by alpha-alanine or glutamine, which are amino acids served by other transport systems. By computer analysis, Na+-dependent taurine uptake (2-1,000 microM) was saturable with an apparent Km of 74.80 +/- 11.87 microM and a Vmax of 53.55 +/- 2.76 pmol.mg protein-1.min-1. With increasing postnatal age, there was a marked decrease in the initial rate and peak intravesicular accumulation of taurine with disappearance of the overshoot by 21 days of age. We conclude 1) a Na+-dependent carrier mechanism for taurine transport is present in the brush-border membrane of suckling rat jejunum and 2) the activity of this carrier decreases after weaning.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for a high affinity, Na+-dependent glutamate transport system in lactating rat mammary tissue

1995 ◽  
Vol 23 (4) ◽  
pp. 567S-567S
Author(s):  
I.D. MILLAR ◽  
D.T. CALVERT ◽  
M.A. LOMAX ◽  
D.B. SHENNAN
Keyword(s):  
Transport System ◽  
Glutamate Transport ◽  
Mammary Tissue ◽  
High Affinity

Epidermal taurine transport in marine mussels

1984 ◽  
Vol 247 (2) ◽  
pp. R346-R355 ◽  
Author(s):  
S. H. Wright ◽  
T. W. Secomb
Keyword(s):  
Amino Acids ◽  
Gill Tissue ◽  
Taurine Transport ◽  
Beta Alanine ◽  
Half Saturation Constant ◽  
Marine Mussels ◽  
Uptake Process ◽  
High Concentrations ◽  
Taurine Uptake ◽  
Convective Movement

We examined the structural specificity and kinetic characteristics of epidermal taurine transport in the marine mussels Mytilus edulis and M. californianus. The gill was the primary site of taurine uptake in both species, responsible for 70% of the accumulation of radioactively labeled substrate. Taurine transport was inhibited by short-chain beta-amino acids, including beta-alanine and beta-aminobutyric acid (beta-ABA), and by gamma-ABA; alpha-neutral, acidic, and basic amino acids had no effect on this transport. The uptake process was clearly a saturable phenomenon and was adequately described by Michaelis-Menten-type kinetics in both intact animals and isolated preparations of gill. The maximal rates of taurine uptake, expressed per gram of gill tissue, were 8.4 and 3.2 mumol X g-1 X h-1 for M. edulis and M. californianus, respectively. In intact mussels the half-saturation constant for both species ranged from 5 to 8 microM. A mathematical model was developed that describes the epidermal transport of taurine in the gill of the actively pumping mussel. The model takes into account the geometry and pattern of water flow in the gill. Calculations based on this model indicate that because of the convective movement of water through the gill, the actual Michaelis constant of the taurine transporter must be much lower (i.e., 0.5-2.5 microM) than the half-saturation constants determined with intact animals and isolated gills. The model also predicts that the presence of the transporter in the gill can result in a significant reaccumulation of taurine lost from the gill by passive diffusion. We suggest that epidermal taurine transport is involved with maintenance of the high concentrations of this compound commonly associated with gill tissue in mussels.

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