Expression of three glutamate transporter subtype mRNAs in human brain regions and peripheral tissues

doi:10.1016/0169-328X(95)00297-6

Molecular Brain Research

Volume 36, Issue 1, February 1996, Pages 189-192

https://doi.org/10.1016/0169-328X(95)00297-6 Get rights and content

Abstract

We compared the expression of mRNAs for three human glutamate transporter subtypes in human central nervous system (CNS) and other organs by Northern blot analysis. hGLT-1 and hGluT-1 mRNAs were most abundantly expressed in the brain, while hEAAC1 mRNA expression (3.8 kb and 2.4 kb) was strongest in peripheral organs. All subtype mRNAs were expressed throughout the CNS with hGLT-1 predominant in frontal lobe, striatum and limbic areas, and hGluT-1 predominant in cerebellum.

References (18)

D.W. Choi
Glutamate neurotoxicity and disease of the nervous system
Neuron
(1988)
A.P. Feinberg et al.
A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity
Anal. Biochem.
(1983)
H. Ihara et al.
Induction of thromboxane synthase and prostaglandin endoperoxide synthase mRNAs in human erythroleukemia cells by phorbol ester
FEBS
(1992)
H. Kawakami et al.
Cloning and expression of human glutamate transporter
Biochem. Biophys. Res. Commun.
(1994)
A.M. Palmer et al.
Excitatory amino acid-releasing and cholinergic neurons in Alzheimer's disease
Neurosci. Lett.
(1986)
J.D. Rothstein et al.
Localization of neuronal and glial glutamate transporter
Neuron
(1994)
P. Shashidharan et al.
Neuron specific human glutamate transporter: molecular cloning, characterization and expression in human brain
Brain Res.
(1994)
P. Shashidharan et al.
Molecular cloning of human brain glutamate/aspartate transporter II
Biochem. Biophys. Acta
(1994)
K. Tanaka
Expression cloning of a rat glutamate transporter
Neurosci. Res. N.Y.
(1993)

There are more references available in the full text version of this article.

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Glutamate in GABAergic neurons has two origins. First, glutamate transporters (excitatory amino acid carrier 1) in the presynaptic terminals of GABAergic neurons allow glutamate entry into these interneurons (Kanai and Hediger, 1992; Nakayama et al., 1996). Second, glutamate enters astrocytes via astrocyte-specific glutamate transporter-1 and is converted to glutamine by glutamine synthases and then released from astrocytes (Arriza et al., 1994; Pines et al., 1992).
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GLT-1 is expressed in pancreas and liver, but the levels are 100-fold or more higher in brain (Berger & Hediger, 2006). EAAC1 is expressed in intestine, kidney, heart, lung, placenta, and liver (Nakayama, Kawakami, Tanaka, & Nakamura, 1996). Low levels of EAAT4 mRNA are found in placenta, and EAAT5 is expressed in liver, kidney, intestine, heart, lung, and skeletal muscle (Gegelashvili & Schousboe, 1998; Lee et al., 2013).
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Localization and function of the brain excitatory amino acid transporter type 1 in cardiac mitochondria
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Glutamate metabolism is known to be important for growth and development of the human fetus. The glutamate transporters EAAT1, EAAT2 and EAAT3 are key components of the glutamate–glutamine cycle and responsible for active transport of glutamate over the cell membrane. The placenta is thought to regulate glutamate transport during fetal development. Glutamate transporters have been found in placentae of rats, but their distribution in the human placenta is unknown. Therefore, the distribution of glutamate transporters EAAT1, EAAT2 and EAAT3 were analysed in the human placenta during normal pregnancies ending between 8 and 40 weeks of gestation and in placentae of intrauterine growth restricted infants with gestational ages between 28 and 35 weeks of pregnancy. Using immunohistochemistry, EAAT1 expression was found in the syncytiotrophoblast layer, while EAAT2 was detected in the syncytiotrophoblast layer and in endothelial cells of about 5 per cent of all fetal blood vessels. EAAT3 was observed in the endothelium of the fetal blood vessels in all placentae examined. However, expression was also found in the syncytio- and the cytotrophoblast layer of the fetal villi at 8 weeks of gestational age. The expression patterns of EAAT1, EAAT2 and EAAT3 suggest involvement in active transport of glutamate between the fetal and maternal blood circulation. No differences were found in the distribution of the glutamate transporters between control and IUGR placentae. Our data show specific localization of EAAT1, EAAT2 and EAAT3 in the human placenta during development.
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Short communicationExpression of three glutamate transporter subtype mRNAs in human brain regions and peripheral tissues

Abstract

Neuron

Anal. Biochem.

FEBS

Biochem. Biophys. Res. Commun.

Neurosci. Lett.

Neuron

Brain Res.

Biochem. Biophys. Acta

Neurosci. Res. N.Y.

Short communication
Expression of three glutamate transporter subtype mRNAs in human brain regions and peripheral tissues