scholarly journals Localization and Functional Relevance of System A Neutral Amino Acid Transporters in Cultured Hippocampal Neurons

2002 ◽  
Vol 277 (12) ◽  
pp. 10467-10473 ◽  
Author(s):  
Simona Armano ◽  
Silvia Coco ◽  
Alberto Bacci ◽  
Elena Pravettoni ◽  
Ursula Schenk ◽  
...  
Keyword(s):  
Amino Acid ◽  
Hippocampal Neurons ◽  
Neutral Amino Acid ◽  
Amino Acid Transporters ◽  
System A ◽  
Functional Relevance ◽  
Cultured Hippocampal Neurons

Na+-dependent neutral amino acid transporters A, ASC, and N of the blood-brain barrier: mechanisms for neutral amino acid removal

2004 ◽  
Vol 287 (4) ◽  
pp. E622-E629 ◽  
Author(s):  
Robyn L. O'Kane ◽  
Juan R. Viña ◽  
Ian Simpson ◽  
Richard A. Hawkins
Keyword(s):  
Amino Acid ◽  
Blood Brain Barrier ◽  
Functional Organization ◽  
Extracellular Fluid ◽  
Neutral Amino Acid ◽  
Brain Barrier ◽  
Amino Acid Transporters ◽  
System A ◽  
Blood Brain ◽  
Voltage Dependent

Four Na+-dependent transporters of neutral amino acids (NAA) are known to exist in the abluminal membranes (brain side) of the blood-brain barrier (BBB). This article describes the kinetic characteristics of systems A, ASC, and N that, together with the recently described Na+-dependent system for large NAA (Na+-LNAA), provide a basis for understanding the functional organization of the BBB. The data demonstrate that system A is voltage dependent (3 positive charges accompany each molecule of substrate). Systems ASC and N are not voltage dependent. Each NAA is a putative substrate for at least one system, and several NAA are transported by as many as three. System A transports Pro, Ala, His, Asn, Ser, and Gln; system ASC transports Ser, Gly, Met, Val, Leu, Ile, Cys, and Thr; system N transports Gln, His, Ser, and Asn; Na+-LNAA transports Leu, Ile, Val, Trp, Tyr, Phe, Met, Ala, His, Thr, and Gly. Together, these four systems have the capability to actively transfer every naturally occurring NAA from the extracellular fluid (ECF) to endothelial cells and thence to the circulation. The existence of facilitative transport for NAA (L1) on both membranes provides the brain access to essential NAA. The presence of Na+-dependent carriers on the abluminal membrane provides a mechanism by which NAA concentrations in the ECF of brain are maintained at ∼10% of those of the plasma.

Involvement of sodium-coupled neutral amino acid transporters (system A) in l-proline transport in the rat retinal pericytes

2020 ◽  
Vol 35 (5) ◽  
pp. 410-416
Author(s):  
Nobuyuki Zakoji ◽  
Kosuke Tajima ◽  
Daisuke Yoneyama ◽  
Shin-ichi Akanuma ◽  
Yoshiyuki Kubo ◽  
...  
Keyword(s):  
Amino Acid ◽  
Neutral Amino Acid ◽  
Amino Acid Transporters ◽  
Proline Transport ◽  
System A ◽  
Retinal Pericytes

scholarly journals Inhibitors of the Neutral Amino Acid Transporters ASCT1 and ASCT2 Are Effective in In Vivo Models of Schizophrenia and Visual Dysfunction

2018 ◽  
Vol 367 (2) ◽  
pp. 292-301 ◽  
Author(s):  
Yong-Xin Li ◽  
Jia-Ying Yang ◽  
Miguel Alcantara ◽  
Grigor Abelian ◽  
Ashutosh Kulkarni ◽  
...  
Keyword(s):  
Amino Acid ◽  
Neutral Amino Acid ◽  
Amino Acid Transporters ◽  
Visual Dysfunction ◽  
In Vivo Models

scholarly journals Electrogenic Na+-dependentl-alanine transport in the lizard duodenum. Involvement of systems A and ASC

2001 ◽  
Vol 280 (3) ◽  
pp. R612-R622
Author(s):  
Virtudes Medina ◽  
Antonio Lorenzo ◽  
Mario Dı́az
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Short Circuit ◽  
Duodenal Mucosa ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
Transport Activity ◽  
System A ◽  
Alanine Transport ◽  
Gallotia Galloti

l-Alanine transport across the isolated duodenal mucosa of the lizard Gallotia galloti has been studied in Ussing chambers under short-circuit conditions. Net l-alanine fluxes, transepithelial potential difference (PD), and short-circuit current ( Isc) showed concentration-dependent relationships. Na+-dependent l-alanine transport was substantially inhibited by the analog α-methyl aminoisobutyric acid (MeAIB). Likewise, MeAIB fluxes were completely inhibited byl-alanine, indicating the presence of system A for neutral amino acid transport. System A transport activity was electrogenic and exhibited hyperbolic relationships for net MeAIB fluxes, PD, and Isc, which displayed similar apparent K m values. Na+-dependentl-alanine transport, but not MeAIB transport, was partially inhibited by l-serine and l-cysteine, indicating the participation of system ASC. This transport activity represents the major pathway for l-alanine absorption and seemed to operate in an electroneutral mode with a negligible contribution to the l-alanine-induced electrogenicity. It is concluded from the present study that the active Na+-dependent l-alanine transport across the isolated duodenal mucosa of Gallotia galloti results from the independent activity of systems A and ASC for neutral amino acid transport.

scholarly journals Characterization of the amino acid response element within the human sodium-coupled neutral amino acid transporter 2 (SNAT2) System A transporter gene

2006 ◽  
Vol 395 (3) ◽  
pp. 517-527 ◽  
Author(s):  
Stela S. Palii ◽  
Michelle M. Thiaville ◽  
Yuan-Xiang Pan ◽  
Can Zhong ◽  
Michael S. Kilberg
Keyword(s):  
Amino Acid ◽  
Rna Polymerase Ii ◽  
Mammalian Cells ◽  
Amino Acid Transporter ◽  
Neutral Amino Acid ◽  
System A ◽  
Neutral Amino Acid Transporter ◽  
Acid Transporter ◽  
Amino Acid Response

The neutral amino acid transport activity, System A, is enhanced by amino acid limitation of mammalian cells. Of the three gene products that encode System A activity, the one that exhibits this regulation is SNAT2 (sodium-coupled neutral amino acid transporter 2). Fibroblasts that are deficient in the amino acid response pathway exhibited little or no induction of SNAT2 mRNA. Synthesis of SNAT2 mRNA increased within 1–2 h after amino acid removal from HepG2 human hepatoma cells. The amino acid responsive SNAT2 genomic element that mediates the regulation has been localized to the first intron. Increased binding of selected members of the ATF (activating transcription factor) and C/EBP (CCAAT/enhancer-binding protein) families to the intronic enhancer was established both in vitro and in vivo. In contrast, there was no significant association of these factors with the SNAT2 promoter. Expression of exogenous individual ATF and C/EBP proteins documented that specific family members are associated with either activation or repression of SNAT2 transcription. Chromatin immunoprecipitation analysis established in vivo that amino acid deprivation led to increased RNA polymerase II recruitment to the SNAT2 promoter.

scholarly journals Deletion of P2X7 Receptor Decreases Basal Glutathione Level by Changing Glutamate-Glutamine Cycle and Neutral Amino Acid Transporters

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 995 ◽  
Author(s):  
Hana Park ◽  
Ji-Eun Kim
Keyword(s):  
Amino Acid ◽  
P2x7 Receptor ◽  
Neuronal Excitability ◽  
Defense Mechanism ◽  
Glutamate Uptake ◽  
Neutral Amino Acid ◽  
Amino Acid Transporters ◽  
Glutamine Synthase ◽  
Expression Activity ◽  
P2x7r Activation

Glutathione (GSH) is an endogenous tripeptide antioxidant that consists of glutamate-cysteine-glycine. GSH content is limited by the availability of glutamate and cysteine. Furthermore, glutamine is involved in the regulation of GSH synthesis via the glutamate–glutamine cycle. P2X7 receptor (P2X7R) is one of the cation-permeable ATP ligand-gated ion channels, which is involved in neuronal excitability, neuroinflammation and astroglial functions. In addition, P2X7R activation decreases glutamate uptake and glutamine synthase (GS) expression/activity. In the present study, we found that P2X7R deletion decreased the basal GSH level without altering GSH synthetic enzyme expressions in the mouse hippocampus. P2X7R deletion also increased expressions of GS and ASCT2 (a glutamine:cysteine exchanger), but diminished the efficacy of N-acetylcysteine (NAC, a GSH precursor) in the GSH level. SIN-1 (500 μM, a generator nitric oxide, superoxide and peroxynitrite), which facilitates the cystine–cysteine shuttle mediated by xCT (a glutamate/cystein:cystine/NAC antiporter), did not affect basal GSH concentration in WT and P2X7R knockout (KO) mice. However, SIN-1 effectively reduced the efficacy of NAC in GSH synthesis in WT mice, but not in P2X7R KO mice. Therefore, our findings indicate that P2X7R may be involved in the maintenance of basal GSH levels by regulating the glutamate–glutamine cycle and neutral amino acid transports under physiological conditions, which may be the defense mechanism against oxidative stress during P2X7R activation.

scholarly journals The role of system A for neutral amino acid transport in the regulation of cell volume

2001 ◽  
Vol 18 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Ovidio Bussolati ◽  
Valeria Dall'Asta ◽  
Renata Franchi-Gazzola ◽  
Roberto Sala ◽  
Bianca Maria Rotoli ◽  
...  
Keyword(s):  
Amino Acid ◽  
Cell Volume ◽  
Amino Acid Transport ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
System A
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