PMID- 34961934
OWN - NLM
STAT- MEDLINE
DCOM- 20220420
LR  - 20220613
IS  - 1528-1167 (Electronic)
IS  - 0013-9580 (Linking)
VI  - 63
IP  - 2
DP  - 2022 Feb
TI  - Mutations associated with epileptic encephalopathy modify EAAT2 anion channel 
      function.
PG  - 388-401
LID - 10.1111/epi.17154 [doi]
AB  - OBJECTIVE: Mutations in the gene solute carrier family member 1A2 (SLC1A2) 
      encoding the excitatory amino acid transporter 2 (EAAT2) are associated with 
      severe forms of epileptic encephalopathy. EAAT2 is expressed in glial cells and 
      presynaptic nerve terminals and represents the main l-glutamate uptake carrier in 
      the mammalian brain. It does not only function as a secondary active glutamate 
      transporter, but also as an anion channel. How naturally occurring mutations 
      affect these two transport functions of EAAT2 and how such alterations cause 
      epilepsy is insufficiently understood. METHODS: Here we studied the functional 
      consequences of three disease-associated mutations, which predict amino acid 
      exchanges p.Gly82Arg (G82R), p.Leu85Pro (L85P), and p.Pro289Arg (P289R), by 
      heterologous expression in mammalian cells, biochemistry, confocal imaging, and 
      whole-cell patch-clamp recordings of EAAT2 l-glutamate transport and anion 
      current. RESULTS: G82R and L85P exchange amino acid residues that contribute to 
      the formation of the EAAT anion pore. They enlarge the pore diameter sufficiently 
      to permit the passage of l-glutamate and thus function as l-glutamate efflux 
      pathways. The mutation P289R decreases l-glutamate uptake, but increases anion 
      currents despite a lower membrane expression. SIGNIFICANCE: l-glutamate 
      permeability of the EAAT anion pore is an unexpected functional consequence of 
      naturally occurring single amino acid substitutions. l-glutamate efflux through 
      mutant EAAT2 anion channels will cause glutamate excitotoxicity and neuronal 
      hyperexcitability in affected patients. Antagonists that selectively suppress the 
      EAAT anion channel function could serve as therapeutic agents in the future.
CI  - (c) 2021 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of 
      International League Against Epilepsy.
FAU - Kovermann, Peter
AU  - Kovermann P
AUID- ORCID: 0000-0001-5296-4918
AD  - Molekular- und Zellphysiologie (IBI-1) Forschungszentrum Julich, Institute of 
      Biological Information Processing, Julich, Germany.
FAU - Kolobkova, Yulia
AU  - Kolobkova Y
AUID- ORCID: 0000-0001-9933-2918
AD  - Molekular- und Zellphysiologie (IBI-1) Forschungszentrum Julich, Institute of 
      Biological Information Processing, Julich, Germany.
FAU - Franzen, Arne
AU  - Franzen A
AD  - Molekular- und Zellphysiologie (IBI-1) Forschungszentrum Julich, Institute of 
      Biological Information Processing, Julich, Germany.
FAU - Fahlke, Christoph
AU  - Fahlke C
AUID- ORCID: 0000-0001-8602-9952
AD  - Molekular- und Zellphysiologie (IBI-1) Forschungszentrum Julich, Institute of 
      Biological Information Processing, Julich, Germany.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20211228
PL  - United States
TA  - Epilepsia
JT  - Epilepsia
JID - 2983306R
RN  - 0 (Amino Acids)
RN  - 0 (Anions)
RN  - 0 (Excitatory Amino Acid Transporter 2)
RN  - 3KX376GY7L (Glutamic Acid)
SB  - IM
MH  - Amino Acids/metabolism
MH  - Animals
MH  - Anions/metabolism
MH  - *Brain Diseases
MH  - *Excitatory Amino Acid Transporter 2/chemistry/genetics/metabolism
MH  - Glutamic Acid/genetics/metabolism
MH  - Humans
MH  - Mammals/metabolism
MH  - Mutation/genetics
OTO - NOTNLM
OT  - SLC1A2
OT  - epilepsy
OT  - gain-of-function
OT  - glutamate transporter
EDAT- 2021/12/29 06:00
MHDA- 2022/04/21 06:00
CRDT- 2021/12/28 06:41
PHST- 2021/12/09 00:00 [revised]
PHST- 2021/10/08 00:00 [received]
PHST- 2021/12/09 00:00 [accepted]
PHST- 2021/12/29 06:00 [pubmed]
PHST- 2022/04/21 06:00 [medline]
PHST- 2021/12/28 06:41 [entrez]
AID - 10.1111/epi.17154 [doi]
PST - ppublish
SO  - Epilepsia. 2022 Feb;63(2):388-401. doi: 10.1111/epi.17154. Epub 2021 Dec 28.