Expression and function of glutamine transporters SN1 (SNAT3) and SN2 (SNAT5) in retinal Muller cells.

Article Details

Citation

Copy to clipboard

Umapathy NS, Li W, Mysona BA, Smith SB, Ganapathy V

Expression and function of glutamine transporters SN1 (SNAT3) and SN2 (SNAT5) in retinal Muller cells.

Invest Ophthalmol Vis Sci. 2005 Nov;46(11):3980-7.

PubMed ID

16249471 [ View in PubMed

]

Abstract

PURPOSE: The expression and function of the glutamine transporters ATA1 and ATA2 (isoforms of system A), SN1 and SN2 (isoforms of system N), and LAT1 and LAT2 (isoforms of system L) were investigated in Muller cells in a rat Muller cell line (rMC1) and primary cultures of mouse Muller cells. METHODS: Glutamine uptake in rMC1 cells and primary Muller cells was measured. The relative contributions of various transport systems to glutamine uptake were determined based on the differential substrate specificities and Na(+) dependence of individual transport systems. RT-PCR was used to analyze the expression of transporter-specific mRNAs. RESULTS: Three different transport systems participated in glutamine uptake in rMC1 cells: system L (Na(+)-independent), system A (Na(+)-dependent and alpha-(methylamino)isobutyric acid [MeAIB]-sensitive), and system N (Na(+)-dependent and MeAIB-insensitive). System N was the principal contributor (approximately 70%); the contributions of systems A and L were relatively lesser (20% and <10%, respectively). The functional features of Na(+)-dependent and MeAIB-insensitive glutamine uptake were similar to the known characteristics of clones of SN1 and SN2. Glutamine uptake in primary Muller cells behaved in a manner similar to that in rMC1 cells. mRNA transcripts specific for ATA1, ATA2, SN1, SN2, LAT1, and LAT2 were expressed in Muller cells. CONCLUSIONS: System N (SN1 as well as SN2) is responsible for most of the glutamine uptake in Muller cells. Because system N is capable of mediating the release of glutamine from the cells, its abundant expression in Muller cells is of importance in the handling of glutamine in the retina.

DrugBank Data that Cites this Article

Drug Transporters

Drug	Transporter	Kind	Organism	Pharmacological Action	Actions
L-Glutamine	Large neutral amino acids transporter small subunit 2	Protein	Humans	Unknown	Substrate	Details
L-Glutamine	Sodium-coupled neutral amino acid transporter 3	Protein	Humans	Unknown	Substrate	Details