Glutamine uptake and expression of mRNA's of glutamine transporting proteins in mouse cerebellar and cerebral cortical astrocytes and neurons.
The relative roles of the three sodium-dependent transport systems: A, ASC and N in the uptake of [3H]Gln, and the compatibility of the uptake characteristics with the expression of mRNAs coding for the Gln transporting molecules, were examined in primary cultures of astrocytes and neurons derived from mouse cerebellum, a glutaminergic system-enriched structure, and in cerebral cortex. Gln uptake activity (Vmax) was higher in cerebellar astrocytes or neurons than in their cerebral cortical counterparts. The N-methylamino-isobutyric acid (MeAiB)- and pH-sensitive, system A-mediated component of the uptake, and the uptake of [14C]MeAiB itself, was much more active in neurons than in astrocytes derived from either region. Also, the expression of mRNA for GlnT (SAT1), a system A isoform specific for Gln, was only expressed in neurons derived from both structures, while an alanine (Ala)-preferring system A transporter, SAT2, was expressed in neurons and astrocytes from either region. System ASC-mediated Gln uptake and expression of ASCT2 mRNA were in both structures more pronounced in astrocytes than in neurons, consistent with the postulated role of ASCT2 in the efflux of de novo synthesized Gln from astrocytes. System N-mediated (threonine+MeAiB-inhibitable) Gln uptake showed comparable activities in all four types of cells, which is compatible with the ubiquitous expression of NAT2 mRNA-a mouse brain-specific N-system isoform.
Dolińska
Monika
M
Department of Neurotoxicology, Medical Research Centre, Polish Academy of Sciences, Pawiñskiego St. 5, Warsaw 02-106, Poland.
Zabłocka
Barbara
B
Sonnewald
Ursula
U
Albrecht
Jan
J
D026924:Amino Acid Transport System A / Q000378:metabolism; D026962:Amino Acid Transport System ASC / Q000378:metabolism; D026905:Amino Acid Transport Systems; D026923:Amino Acid Transport Systems, Basic / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology* / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005973:Glutamine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D051379:Mice; D015778:Minor Histocompatibility Antigens; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D026924:Amino Acid Transport System A; D026962:Amino Acid Transport System ASC; D026905:Amino Acid Transport Systems; D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D015778:Minor Histocompatibility Antigens; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C498850:Slc1a5 protein, mouse; C432411:Slc38a1 protein, mouse; C498798:Slc38a2 protein, mouse; D005973:Glutamine; D010042:Ouabain