Excitatory amino acid transporter 2

Excitatory amino acid transporter 2 (EAAT2) also known as solute carrier family 1 member 2 (SLC1A2) and glutamate transporter 1 (GLT-1) is a protein that in humans is encoded by the SLC1A2 gene.^[5][6] Alternatively spliced transcript variants of this gene have been described, but their full-length nature is not known.^[6]

SLC1A2
Identifiers
Aliases	SLC1A2, EAAT2, GLT-1, HBGT, solute carrier family 1 member 2, EIEE41, DEE41
External IDs	OMIM: 600300 MGI: 101931 HomoloGene: 3075 GeneCards: SLC1A2
Gene location (Human) Chr. Chromosome 11 (human)^[1] Band 11p13 Start 35,251,205 bp^[1] End 35,420,063 bp^[1]
Gene location (Mouse) Chr. Chromosome 2 (mouse)^[2] Band 2 E2|2 54.13 cM Start 102,489,004 bp^[2] End 102,621,129 bp^[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in endothelial cell Brodmann area 23 entorhinal cortex external globus pallidus middle temporal gyrus parietal lobe postcentral gyrus internal globus pallidus nucleus accumbens caudate nucleus Top expressed in olfactory tubercle subiculum globus pallidus mammillary body medial dorsal nucleus medial geniculate nucleus ventral tegmental area medial vestibular nucleus dorsal tegmental nucleus ventromedial nucleus More reference expression data BioGPS More reference expression data
Gene ontology Molecular function anion transmembrane transporter activity protein binding symporter activity L-glutamate transmembrane transporter activity amino acid transmembrane transporter activity glutamate:sodium symporter activity high-affinity glutamate transmembrane transporter activity metal ion binding Cellular component integral component of membrane membrane plasma membrane cell surface axon axolemma integral component of plasma membrane glutamatergic synapse integral component of presynaptic membrane Biological process cellular response to extracellular stimulus chemical synaptic transmission positive regulation of glucose import response to amino acid response to light stimulus multicellular organism growth D-aspartate import across plasma membrane ion transport nervous system development glutamate secretion telencephalon development anion transmembrane transport adult behavior response to wounding multicellular organism aging visual behavior protein homotrimerization L-glutamate import across plasma membrane amino acid transport L-glutamate transmembrane transport neurotransmitter reuptake Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 6506 20511 Ensembl ENSG00000110436 ENSMUSG00000005089 UniProt P43004 P43006 RefSeq (mRNA) NM_001195728 NM_001252652 NM_004171 NM_001077514 NM_001077515 NM_011393 NM_001361018 RefSeq (protein) NP_001182657 NP_001239581 NP_004162 NP_001070982 NP_001070983 NP_035523 NP_001347947 Location (UCSC) Chr 11: 35.25 – 35.42 Mb Chr 2: 102.49 – 102.62 Mb PubMed search ^[3] ^[4]
Wikidata
View/Edit Human View/Edit Mouse

Function

SLC1A2 / EAAT2 is a member of a family of the solute carrier family of proteins. The membrane-bound protein is the principal transporter that clears the excitatory neurotransmitter glutamate from the extracellular space at synapses in the central nervous system. Glutamate clearance is necessary for proper synaptic activation and to prevent neuronal damage from excessive activation of glutamate receptors.^[6] EAAT2 is responsible for over 90% of glutamate reuptake within the brain.^[7][8]

 

This diagram shows the tissue distribution of glutamate transporter 1 (EAAT2) in the brain.^[7]

Clinical significance

Mutations in and decreased expression of this protein are associated with amyotrophic lateral sclerosis (ALS).^[6] The drug riluzole approved for the treatment of ALS upregulates EAAT2.^[9]

Ceftriaxone, an antibiotic, has been shown to induce/enhance the expression of EAAT2, resulting in reduced glutamate activity.^[10] Ceftriaxone has been shown to reduce the development and expression of tolerance to opiates and other drugs of abuse. EAAT2 may possess an important role in drug addiction and tolerance to addictive drugs.^[11]

Upregulation of EAAT2 (GLT-1) causes impairment of prepulse inhibition, a sensory gating deficit present in schizophrenics and schizophrenia animal models.^[12][13] Some antipsychotics have been shown to reduce the expression of EAAT2.^[14][15]

Interactions

SLC1A2 has been shown to interact with JUB.^[16]

As a drug target

EAAT2/GLT-1, being the most abundant subtype of glutamate transporter in the CNS, plays a key role in regulation of glutamate neurotransmission. Dysfunction of EAAT2 has been correlated with various pathologies such as traumatic brain injury, stroke, Amyotrophic lateral sclerosis (ALS), Alzheimer's disease, among others. Therefore, activators of the function or enhancers of the expression of EAAT2/GLT-1 could serve as a potential therapy for these conditions. Translational activators of EAAT2/GLT-1, such as ceftriaxone and LDN/OSU-0212320, have been described to have significant protective effects in animal models of ALS and epilepsy. In addition, pharmacological activators of the activity of EAAT2/GLT-1 have been explored for decades and are currently emerging as promising tools for neuroprotection, having potential advantages over expression activators.^[17]

DL-TBOA, WAY-213,613, and dihydrokainic acid are known inhibitors of the protein, and function as excitotoxins. They can be considered a novel class of nerve agent toxins, inducing toxic levels of glutamate through transport inhibition in a manner analogous to the effect of sarin on cholinesterase. Antidotes for such a poisoning have never been formally tested for efficacy and are not readily available for medical use.^[18]

Addiction to certain drugs (e.g., cocaine, heroin, alcohol, and nicotine) is correlated with a persistent reduction in the expression of EAAT2 in the nucleus accumbens (NAcc);^[19] the reduced expression of EAAT2 in this region is implicated in addictive drug-seeking behavior.^[19] In particular, the long-term dysregulation of glutamate neurotransmission in the NAcc of addicts is associated with an increase in vulnerability to relapse after re-exposure to the addictive drug or its associated drug cues.^[19] Drugs which help to normalize the expression of EAAT2 in this region, such as N-acetylcysteine, have been proposed as an adjunct therapy for the treatment of addiction to cocaine, nicotine, alcohol, and other drugs.^[19]

See also

• Glutamate transporter
• Solute carrier family

References

1. GRCh38: Ensembl release 89: ENSG00000110436 – Ensembl, May 2017
2. GRCm38: Ensembl release 89: ENSMUSG00000005089 – Ensembl, May 2017
3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
5. Pines G, Danbolt NC, Bjørås M, Zhang Y, Bendahan A, Eide L, Koepsell H, Storm-Mathisen J, Seeberg E, Kanner BI (Dec 1992). "Cloning and expression of a rat brain L-glutamate transporter". Nature. 360 (6403): 464–7. Bibcode:1992Natur.360..464P. doi:10.1038/360464a0. PMID 1448170. S2CID 4243369.
6. "Entrez Gene: SLC1A2 solute carrier family 1 (glial high affinity glutamate transporter), member 2".
7. Rao P, Yallapu MM, Sari Y, Fisher PB, Kumar S (July 2015). "Designing Novel Nanoformulations Targeting Glutamate Transporter Excitatory Amino Acid Transporter 2: Implications in Treating Drug Addiction". J. Pers. Nanomed. 1 (1): 3–9. PMC 4666545. PMID 26635971. The glutamate transporter 1 (GLT1)/ excitatory amino acid transporter 2 (EAAT2) is responsible for the reuptake of more than 90% glutamate in the CNS [12–14].
8. Holmseth S; Scott HA; Real K; Lehre KP; Leergaard TB; Bjaalie JG; Danbolt NC (2009). "The concentrations and distributions of three C-terminal variants of the GLT1 (EAAT2; slc1a2) glutamate transporter protein in rat brain tissue suggest differential regulation". Neuroscience. 162 (4): 1055–71. doi:10.1016/j.neuroscience.2009.03.048. PMID 19328838. S2CID 41615013. Since then, a family of five high-affinity glutamate transporters has been characterized that is responsible for the precise regulation of glutamate levels at both synaptic and extrasynaptic sites, although the glutamate transporter 1 (GLT1) is responsible for more than 90% of glutamate uptake in the brain.3 The importance of GLT1 is further highlighted by the large number of neuropsychiatric disorders associated with glutamate-induced neurotoxicity.
   
   Clarification of nomenclature
   The major glial glutamate transporter is referred to as GLT1 in the rodent literature and excitatory amino acid transporter 2 (EAAT2) in the human literature.
9. Carbone M, Duty S, Rattray M (2012). "Riluzole elevates GLT-1 activity and levels in striatal astrocytes". Neurochem. Int. 60 (1): 31–8. doi:10.1016/j.neuint.2011.10.017. PMC 3430367. PMID 22080156.
10. Lee SG, Su ZZ, Emdad L, Gupta P, Sarkar D, Borjabad A, Volsky DJ, Fisher PB (May 2008). "Mechanism of ceftriaxone induction of excitatory amino acid transporter-2 expression and glutamate uptake in primary human astrocytes". J. Biol. Chem. 283 (19): 13116–23. doi:10.1074/jbc.M707697200. PMC 2442320. PMID 18326497.
11. Reissner KJ, Kalivas PW (2010). "Using glutamate homeostasis as a target for treating addictive disorders". Behav Pharmacol. 21 (5–6): 514–22. doi:10.1097/FBP.0b013e32833d41b2. PMC 2932669. PMID 20634691.
12. Bellesi M, Melone M, Gubbini A, Battistacci S, Conti F (2009). "GLT-1 upregulation impairs prepulse inhibition of the startle reflex in adult rats". Glia. 57 (7): 703–13. doi:10.1002/glia.20798. PMID 18985735. S2CID 3222131.
13. Bellesi M, Conti F (2010). "The mGluR2/3 agonist LY379268 blocks the effects of GLT-1 upregulation on prepulse inhibition of the startle reflex in adult rats". Neuropsychopharmacology. 35 (6): 1253–60. doi:10.1038/npp.2009.225. PMC 3055342. PMID 20072121.
14. Schmitt A, Zink M, Petroianu G, May B, Braus DF, Henn FA (2003). "Decreased gene expression of glial and neuronal glutamate transporters after chronic antipsychotic treatment in rat brain". Neurosci. Lett. 347 (2): 81–4. doi:10.1016/S0304-3940(03)00653-0. PMID 12873733. S2CID 43706291.
15. Vallejo-Illarramendi A, Torres-Ramos M, Melone M, Conti F, Matute C (2005). "Clozapine reduces GLT-1 expression and glutamate uptake in astrocyte cultures". Glia. 50 (3): 276–9. doi:10.1002/glia.20172. PMID 15739191. S2CID 18972974.
16. Marie H, Billups D, Bedford FK, Dumoulin A, Goyal RK, Longmore GD, Moss SJ, Attwell D (February 2002). "The amino terminus of the glial glutamate transporter GLT-1 interacts with the LIM protein Ajuba". Mol. Cell. Neurosci. 19 (2): 152–64. doi:10.1006/mcne.2001.1066. PMID 11860269. S2CID 45768895.
17. Fontana AC (June 20, 2015). "Current approaches to enhance glutamate transporter function and expression". Journal of Neurochemistry. 134 (6): 982–1007. doi:10.1111/jnc.13200. PMID 26096891.
18. KEIKO SHIMAMOTO, BRUNO LEBRUN, YOSHIMI YASUDA-KAMATANI, MASAHIRO SAKAITANI, YASUSHI SHIGERI, NOBORU YUMOTO, and TERUMI NAKAJIMA (February 1998). "DL-threo-b-Benzyloxyaspartate, A Potent Blocker of Excitatory Amino Acid Transporters" (PDF). Molecular Pharmacology. 53 (2): 195–201. doi:10.1124/mol.53.2.195. PMID 9463476.{{cite journal}}: CS1 maint: multiple names: authors list (link)
19. McClure EA, Gipson CD, Malcolm RJ, Kalivas PW, Gray KM (2014). "Potential role of N-acetylcysteine in the management of substance use disorders". CNS Drugs. 28 (2): 95–106. doi:10.1007/s40263-014-0142-x. PMC 4009342. PMID 24442756.

Further reading

• Wang Z, Trillo-Pazos G, Kim SY, Canki M, Morgello S, Sharer LR, Gelbard HA, Su ZZ, Kang DC, Brooks AI, Fisher PB, Volsky DJ (2004). "Effects of human immunodeficiency virus type 1 on astrocyte gene expression and function: potential role in neuropathogenesis". J. Neurovirol. 10. 10 (Suppl 1): 25–32. doi:10.1080/jnv.10.s1.25.32. PMID 14982736.
• Arriza JL, Fairman WA, Wadiche JI, Murdoch GH, Kavanaugh MP, Amara SG (1994). "Functional comparisons of three glutamate transporter subtypes cloned from human motor cortex". J. Neurosci. 14 (9): 5559–69. doi:10.1523/jneurosci.14-09-05559.1994. PMC 6577102. PMID 7521911.
• Manfras BJ, Rudert WA, Trucco M, Boehm BO (1994). "Cloning and characterization of a glutamate transporter cDNA from human brain and pancreas". Biochim. Biophys. Acta. 1195 (1): 185–8. doi:10.1016/0005-2736(94)90026-4. PMID 7522567.
• Li X, Francke U (1995). "Assignment of the gene SLC1A2 coding for the human glutamate transporter EAAT2 to human chromosome 11 bands p13-p12". Cytogenet. Cell Genet. 71 (3): 212–3. doi:10.1159/000134111. PMID 7587378.
• Shashidharan P, Wittenberg I, Plaitakis A (1994). "Molecular cloning of human brain glutamate/aspartate transporter II". Biochim. Biophys. Acta. 1191 (2): 393–6. doi:10.1016/0005-2736(94)90192-9. PMID 8172925.
• Andersson B, Wentland MA, Ricafrente JY, Liu W, Gibbs RA (1996). "A "double adaptor" method for improved shotgun library construction". Anal. Biochem. 236 (1): 107–13. doi:10.1006/abio.1996.0138. PMID 8619474.
• Yu W, Andersson B, Worley KC, Muzny DM, Ding Y, Liu W, Ricafrente JY, Wentland MA, Lennon G, Gibbs RA (1997). "Large-scale concatenation cDNA sequencing". Genome Res. 7 (4): 353–8. doi:10.1101/gr.7.4.353. PMC 139146. PMID 9110174.
• Milton ID, Banner SJ, Ince PG, Piggott NH, Fray AE, Thatcher N, Horne CH, Shaw PJ (1997). "Expression of the glial glutamate transporter EAAT2 in the human CNS: an immunohistochemical study". Brain Res. Mol. Brain Res. 52 (1): 17–31. doi:10.1016/S0169-328X(97)00233-7. PMID 9450673.
• Shimamoto K, Lebrun B, Yasuda-Kamatani Y, Sakaitani M, Shigeri Y, Yumoto N, Nakajima T (1998). "DL-threo-beta-benzyloxyaspartate, a potent blocker of excitatory amino acid transporters". Mol. Pharmacol. 53 (2): 195–201. doi:10.1124/mol.53.2.195. PMID 9463476.
• Lin CL, Bristol LA, Jin L, Dykes-Hoberg M, Crawford T, Clawson L, Rothstein JD (1998). "Aberrant RNA processing in a neurodegenerative disease: the cause for absent EAAT2, a glutamate transporter, in amyotrophic lateral sclerosis". Neuron. 20 (3): 589–602. doi:10.1016/S0896-6273(00)80997-6. PMID 9539131.
• Aoki M, Lin CL, Rothstein JD, Geller BA, Hosler BA, Munsat TL, Horvitz HR, Brown RH (1998). "Mutations in the glutamate transporter EAAT2 gene do not cause abnormal EAAT2 transcripts in amyotrophic lateral sclerosis". Ann. Neurol. 43 (5): 645–53. doi:10.1002/ana.410430514. PMID 9585360. S2CID 10885891.
• Trotti D, Aoki M, Pasinelli P, Berger UV, Danbolt NC, Brown RH, Hediger MA (2001). "Amyotrophic lateral sclerosis-linked glutamate transporter mutant has impaired glutamate clearance capacity". J. Biol. Chem. 276 (1): 576–82. doi:10.1074/jbc.M003779200. PMID 11031254.
• Münch C, Schwalenstöcker B, Hermann C, Cirovic S, Stamm S, Ludolph A, Meyer T (2000). "Differential RNA cleavage and polyadenylation of the glutamate transporter EAAT2 in the human brain". Brain Res. Mol. Brain Res. 80 (2): 244–51. doi:10.1016/S0169-328X(00)00139-X. PMID 11038258.
• Honig LS, Chambliss DD, Bigio EH, Carroll SL, Elliott JL (2000). "Glutamate transporter EAAT2 splice variants occur not only in ALS, but also in AD and controls". Neurology. 55 (8): 1082–8. doi:10.1212/wnl.55.8.1082. PMID 11071482. S2CID 26759254.
• Flowers JM, Powell JF, Leigh PN, Andersen P, Shaw CE (2001). "Intron 7 retention and exon 9 skipping EAAT2 mRNA variants are not associated with amyotrophic lateral sclerosis". Ann. Neurol. 49 (5): 643–9. doi:10.1002/ana.1029. PMID 11357955. S2CID 25451450.
• Rimaniol AC, Mialocq P, Clayette P, Dormont D, Gras G (2001). "Role of glutamate transporters in the regulation of glutathione levels in human macrophages". Am. J. Physiol., Cell Physiol. 281 (6): C1964-70. doi:10.1152/ajpcell.2001.281.6.C1964. PMID 11698255. S2CID 3173417.
• Tozaki H, Kanno T, Nomura T, Kondoh T, Kodama N, Saito N, Aihara H, Nagata T, Matsumoto S, Ohta K, Nagai K, Yajima Y, Nishizaki T (2001). "Role of glial glutamate transporters in the facilitatory action of FK960 on hippocampal neurotransmission". Brain Res. Mol. Brain Res. 97 (1): 7–12. doi:10.1016/S0169-328X(01)00304-7. PMID 11744157.
• Palmada M, Kinne-Saffran E, Centelles JJ, Kinne RK (2002). "Benzodiazepines differently modulate EAAT1/GLAST and EAAT2/GLT1 glutamate transporters expressed in CHO cells". Neurochem. Int. 40 (4): 321–6. doi:10.1016/S0197-0186(01)00087-0. PMID 11792462. S2CID 23624873.
• Marie H, Billups D, Bedford FK, Dumoulin A, Goyal RK, Longmore GD, Moss SJ, Attwell D (2002). "The amino terminus of the glial glutamate transporter GLT-1 interacts with the LIM protein Ajuba". Mol. Cell. Neurosci. 19 (2): 152–64. doi:10.1006/mcne.2001.1066. PMID 11860269. S2CID 45768895.
• Reye P, Sullivan R, Fletcher EL, Pow DV (2002). "Distribution of two splice variants of the glutamate transporter GLT1 in the retinas of humans, monkeys, rabbits, rats, cats, and chickens". J. Comp. Neurol. 445 (1): 1–12. doi:10.1002/cne.10095. PMID 11891650. S2CID 23382118.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.