Keynote Conference - Interevent

Symp#17 Glia
Chair Flávia Carvalho Alcântara Gomes
GLAST/EAAT1 induces Glutamine release through SNAT3 in cultured chick cerebellar Bergmann glial cells
Angelina Rodriguez 1 and Arturo Ortega 2
1 Facultad de Química, Universidad Autónoma de Querétaro, Querétaro, Mexico., 2 Departamento de Genética y
Biología Molecular, Cinvestav-IPN, México DF, Mexico.
Glutamate is the main excitatory neurotransmitter in the vertebrate brain. Once released, its extracellular levels are
tightly regulated through the action of a family of sodium-dependent glutamate/aspartate transporters profusely
expressed in glial cells. Once internalized into the glial compartment, it is metabolized by glutamine synthetase to
glutamine and released to the synaptic space through sodium-dependent neutral amino acid carriers of the N System.
Glutamine is then taken up by neurons via System A transporters completing the so-called glutamate/glutamine
shuttle.
Although this neuronal/glial coupling was described decades ago, it has only been recently that the biochemical
framework that supports this shuttle has begun to be elucidated. Using the established model of cultured cerebellar
Bergmann glia cells from chick cerebellum, we characterized the functional and physical coupling of glutamate uptake
and glutamine release. A time-dependent glutamate transporter-induced glutamine release could be demonstrated.
Furthermore, D-aspartate, a specific glutamate transporter ligand, was capable to enhance the coimmunoprecipitation
of the glutamate and glutamine transporters, whereas glutamine tended to reduce this
association. Our results clearly pointout that glial cells that enwrap glutamatergic synapses act as sensors of neuronal
activity and through their contribution to the neurotransmitter recycling, could well the rate-limiting step of
glutamatergic synaptic function.
Understanding Neuron-Glia Interactions: Models Matter
Frank W. Pfrieger
Institute of Cellular and Integrative Neurosciences, CNRS UPR 3212, University of Strasbourg, Strasbourg, France
Brain development and function depend on interactions of neurons and different type of glial cells. Within the last
years, we have developed new experimental approaches that allow to study these interactions in vitro and in vivo,
with a focus on the retina. In my presentation, I will summarize our results, which indicate contributions of astroglial
cells to synapse development, neuronal volume regulation and cholesterol homeostasis in the brain.
Adan Aguirre
Department of Pharmacological Sciences, 442 Center for Molecular Medicine, Stony Brook University, , Stony Brook,
NY 11794-5140
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