Deletion of Neuronal GLT-1 in Mice Reveals Its Role in Synaptic Glutamate Homeostasis and Mitochondrial Function.

Autor:	McNair LF; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark., Andersen JV; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark., Aldana BI; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark., Hohnholt MC; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark., Nissen JD; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark., Sun Y; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Fischer KD; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Sonnewald U; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark.; Department of Neuroscience, Norwegian University of Science and Technology, N-7489 Trondheim, Norway., Nyberg N; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark., Webster SC; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Kapur K; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Rimmele TS; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Barone I; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Hawks-Mayer H; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Lipton JO; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115.; Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts 02115., Hodgson NW; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Hensch TK; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115., Aoki CJ; Center of Neural Science, New York University, New York, New York 10003.; Neuroscience Institute, New York University Langone Medical Center, New York, New York 10016, and., Rosenberg PA; Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115, helle.waagepetersen@sund.ku.dk paul.rosenberg@childrens.harvard.edu.; Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, 02115., Waagepetersen HS; Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark, helle.waagepetersen@sund.ku.dk paul.rosenberg@childrens.harvard.edu.
Jazyk:	angličtina
Zdroj:	The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 2019 Jun 19; Vol. 39 (25), pp. 4847-4863. Date of Electronic Publication: 2019 Mar 29.
DOI:	10.1523/JNEUROSCI.0894-18.2019
Abstrakt:	The glutamate transporter GLT-1 is highly expressed in astrocytes but also in neurons, primarily in axon terminals. We generated a conditional neuronal GLT-1 KO using synapsin 1-Cre (synGLT-1 KO) to elucidate the metabolic functions of GLT-1 expressed in neurons, here focusing on the cerebral cortex. Both synaptosomal uptake studies and electron microscopic immunocytochemistry demonstrated knockdown of GLT-1 in the cerebral cortex in the synGLT-1 KO mice. Aspartate content was significantly reduced in cerebral cortical extracts as well as synaptosomes from cerebral cortex of synGLT-1 KO compared with control littermates. 13 C-Labeling of tricarboxylic acid cycle intermediates originating from metabolism of [U- 13 C]-glutamate was significantly reduced in synGLT-1 KO synaptosomes. The decreased aspartate content was due to diminished entry of glutamate into the tricarboxylic acid cycle. Pyruvate recycling, a pathway necessary for full glutamate oxidation, was also decreased. ATP production was significantly increased, despite unaltered oxygen consumption, in isolated mitochondria from the synGLT-1 KO. The density of mitochondria in axon terminals and perisynaptic astrocytes was increased in the synGLT-1 KO. Intramitochondrial cristae density of synGLT-1 KO mice was increased, suggesting increased mitochondrial efficiency, perhaps in compensation for reduced access to glutamate. SynGLT-1 KO synaptosomes exhibited an elevated oxygen consumption rate when stimulated with veratridine, despite a lower baseline oxygen consumption rate in the presence of glucose. GLT-1 expressed in neurons appears to be required to provide glutamate to synaptic mitochondria and is linked to neuronal energy metabolism and mitochondrial function. SIGNIFICANCE STATEMENT All synaptic transmitters need to be cleared from the extracellular space after release, and transporters are used to clear glutamate released from excitatory synapses. GLT-1 is the major glutamate transporter, and most GLT-1 is expressed in astrocytes. Only 5%-10% is expressed in neurons, primarily in axon terminals. The function of GLT-1 in axon terminals remains unknown. Here, we used a conditional KO approach to investigate the significance of the expression of GLT-1 in neurons. We found multiple abnormalities of mitochondrial function, suggesting impairment of glutamate utilization by synaptic mitochondria in the neuronal GLT-1 KO. These data suggest that GLT-1 expressed in axon terminals may be important in maintaining energy metabolism and biosynthetic activities mediated by presynaptic mitochondria. (Copyright © 2019 the authors.)
Databáze:	MEDLINE
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