title: Expression of the System N transporter (SNAT5/SN2) during development indicates its plausible role in glutamatergic neurotransmission.
abstract: Solute neutral amino acid transporter 5 (SNAT5/SN2) is a member of the System N family, expressed in glial cells in the adult brain, able to transport glutamine, histidine or glycine among other substrates. Its tight association with synapses and its electroneutral mode of operation that allows the bidirectional movement of substrates, supports the idea that this transporter participates in the function of the glutamine-glutamate cycle between neurons and glia. Moreover, SNAT5/SN2 might contribute to the regulation of glycine concentration in glutamatergic synapses and, therefore, to the functioning of the N-methyl-d-aspartate (NMDA) subtype of glutamate receptors. Ontogenic maturation of these synapses occurs postnatally through the coordinate expression of a large number of receptors, transporters, structural and regulatory proteins that ensure the correct operation of the excitatory pathways in the central nervous system. Since the temporal pattern of expression of SNAT5/SN2 is unknown, we analyzed it by immunoblot and immunohistochemical techniques. Results indicate that the expression of SNAT5/SN2 is triggered between the second and third postnatal week in the cerebral cortex, in parallel to the expression of the vesicular glutamate transporter vGLUT1 and the glial glutamate transporter GLT1/EAAT2. In the cerebellum, this process occurs about one week later than in the cerebral cortex. Immunohistochemical staining of cortical sections shows that from postnatal day 14 to adulthood the transporter was expressed exclusively in glial cells. Our results are consistent with the idea that SNAT5/SN2 expression is coordinated with that of other proteins necessary for the operation of glutamatergic synapses and reinforce the existence of a regulatory cross-talk between neurons and glia that orchestrates the building up of these synapses.
authors: Facultad de Química, Universidad Autónoma de Querétaro, Centro Universitario, Querétaro, Mexico. Electronic address: angelina@uaq.mx.
authors: Angelina
authors: A
authors: Rodríguez
authors: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, Mexico.
authors: Arturo
authors: A
authors: Ortega
authors: Facultad de Química, Universidad Autónoma de Querétaro, Centro Universitario, Querétaro, Mexico.
authors: Laura C
authors: LC
authors: Berumen
authors: Facultad de Química, Universidad Autónoma de Querétaro, Centro Universitario, Querétaro, Mexico.
authors: María G
authors: MG
authors: García-Alcocer
authors: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Consejo Superior de Investigaciones Científicas, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
authors: Cecilio
authors: C
authors: Giménez
authors: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Consejo Superior de Investigaciones Científicas, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
authors: Francisco
authors: F
authors: Zafra
mesh_terms: D027322:Amino Acid Transport System X-AG / Q000378:metabolism; D026921:Amino Acid Transport Systems, Neutral / Q000235:genetics* / Q000502:physiology*; D000818:Animals; D027342:Excitatory Amino Acid Transporter 2 / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D051272:Glucose Transporter Type 1 / Q000096:biosynthesis / Q000235:genetics; D018698:Glutamic Acid / Q000502:physiology*; D008297:Male; D009457:Neuroglia / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology*
chemical_list: D027322:Amino Acid Transport System X-AG; D026921:Amino Acid Transport Systems, Neutral; D027342:Excitatory Amino Acid Transporter 2; D051272:Glucose Transporter Type 1; C493395:Slc1a2 protein, rat; C495679:Slc2a1 protein, rat; C442247:Slc38a5 protein, rat; D018698:Glutamic Acid
keywords: Cerebellum; Cerebral cortex; Glutamate transporters; Glutamine transporters; Glycine transporter; Ontogeny