PUBLICATION

Loss of glutamate transporter eaat2a leads to aberrant neuronal excitability, recurrent epileptic seizures, and basal hypoactivity

Authors

Hotz, A.L., Jamali, A., Rieser, N.N., Niklaus, S., Aydin, E., Myren-Svelstad, S., Lalla, L., Jurisch-Yaksi, N., Yaksi, E., Neuhauss, S.C.F.

ID

ZDB-PUB-211101-7

Date

2021

Source

Glia 70(1): 196-214 (Journal)

Registered Authors

Hotz, Adriana, Jurisch-Yaksi, Nathalie, Neuhauss, Stephan

Keywords

astroglia, brain excitability, calcium imaging, eaat2, epilepsy, glutamate, zebrafish

MeSH Terms

Excitatory Amino Acid Transporter 2/genetics
Excitatory Amino Acid Transporter 2/metabolism
Glutamic Acid/metabolism
Epilepsy*/metabolism
Neurons/metabolism
Animals
Astrocytes/metabolism
Seizures/genetics
Seizures/metabolism
Zebrafish*/metabolism

(all 10)

PubMed

34716961 Full text @ Glia

Abstract

Astroglial excitatory amino acid transporter 2 (EAAT2, GLT-1, and SLC1A2) regulates the duration and extent of neuronal excitation by removing glutamate from the synaptic cleft. Hence, an impairment in EAAT2 function could lead to an imbalanced brain network excitability. Here, we investigated the functional alterations of neuronal and astroglial networks associated with the loss of function in the astroglia predominant eaat2a gene in zebrafish. We observed that eaat2a^-/- mutant zebrafish larvae display recurrent spontaneous and light-induced seizures in neurons and astroglia, which coincide with an abrupt increase in extracellular glutamate levels. In stark contrast to this hyperexcitability, basal neuronal and astroglial activity was surprisingly reduced in eaat2a^-/- mutant animals, which manifested in decreased overall locomotion. Our results reveal an essential and mechanistic contribution of EAAT2a in balancing brain excitability, and its direct link to epileptic seizures.

Genes / Markers

Figures

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Expression

Gene	Fish	Conditions	Stage	Anatomy	Assay	Figure
cpEGFP	cu3313Tg	chemical treatment by environment: pentetrazol	Day 5	telencephalon extracellular space	IFL	Fig. 3
cpEGFP	slc1a2b^zh7/zh7; cu3313Tg	standard conditions	Day 5	telencephalon extracellular space	IFL	Fig. 3
gabra1	slc1a2b^zh7/zh7	standard conditions	Day 5	brain	RTPCR	Fig. 5
gad1b	slc1a2b^zh7/zh7	standard conditions	Day 5	brain	RTPCR	Fig. 5
GCaMP	jf4Tg	standard conditions	Day 5	brain	IFL	Fig. 2
GCaMP	jf4Tg	visible light	Day 5	brain	IFL	Fig. 2
GCaMP	nkUAShspzGCaMP6s13aTg; nw7Tg	standard conditions	Day 5	forebrain astrocyte	IFL	Fig. 5
GCaMP	nkUAShspzGCaMP6s13aTg; nw7Tg	standard conditions	Day 5	midbrain astrocyte	IFL	Fig. 5
GCaMP	slc1a2b^zh7/+; jf4Tg	standard conditions	Day 5	brain	IFL	Fig. 2
GCaMP	slc1a2b^zh7/+; jf4Tg	visible light	Day 5	brain	IFL	Fig. 2

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Phenotype

Fish	Conditions	Stage	Phenotype	Figure
cu3313Tg	chemical treatment by environment: pentetrazol	Day 5	telencephalon extracellular space cpEGFP expression increased amount, abnormal	Fig. 3
cu3313Tg	chemical treatment by environment: pentetrazol	Day 5	telencephalon glutamate(1-) increased amount, abnormal	Fig. 3
cu3313Tg	chemical treatment by environment: pentetrazol	Day 5	telencephalon neuronal action potential increased process quality, abnormal	Fig. 3
jf4Tg	visible light	Day 5	brain neuronal action potential increased process quality, abnormal	Fig. 2
slc1a2b^zh7/+	standard conditions	Day 5	heart morphology, normal	Fig. 2
slc1a2b^zh7/+	standard conditions	Day 5	swim bladder inflated, normal	Fig. 2
slc1a2b^zh7/+	standard conditions	Day 5	swimming normal process quality, normal	Fig. 3
slc1a2b^zh7/+	standard conditions	Day 5	whole organism normal length, normal	Fig. 2
slc1a2b^zh7/+; jf4Tg	visible light	Day 5	brain neuronal action potential increased process quality, abnormal	Fig. 2
slc1a2b^zh7/+; nkUAShspzGCaMP6s13aTg; nw7Tg	standard conditions	Day 5	astrocyte regulation of glutamate uptake involved in transmission of nerve impulse normal process quality, normal	Fig. 5

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Mutations / Transgenics

Allele	Construct	Type	Affected Genomic Region
cu3313Tg	Tg(gfap:Eco.GltL-cpEGFP)	Transgenic Insertion
jf4Tg	Tg(elavl3:GCaMP6s)	Transgenic Insertion
nkUAShspzGCaMP6s13aTg	Tg(5xUAS-hsp70l:GCaMP6s)	Transgenic Insertion
nw7Tg	Tg2(gfap:GAL4)	Transgenic Insertion
w2		Point Mutation	mitfa
zf498Tg	Tg(elavl3:GCaMP5G)	Transgenic Insertion
zh7		Small Deletion	slc1a2b

1 - 7 of 7

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Human Disease / Model

Human Disease	Fish	Conditions	Evidence
developmental and epileptic encephalopathy 41	slc1a2b^zh7/zh7	standard conditions	TAS

Sequence Targeting Reagents

Target	Reagent	Reagent Type
slc1a2b	CRISPR1-slc1a2b	CRISPR

Fish

Fish
cu3313Tg
jf4Tg
nkUAShspzGCaMP6s13aTg; nw7Tg
slc1a2b^zh7/+
slc1a2b^zh7/+; cu3313Tg
slc1a2b^zh7/+; jf4Tg
slc1a2b^zh7/+; nkUAShspzGCaMP6s13aTg; nw7Tg
slc1a2b^zh7/+; zf498Tg
slc1a2b^zh7/zh7
slc1a2b^zh7/zh7; cu3313Tg

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Antibodies

Orthology

Engineered Foreign Genes

Marker	Marker Type	Name
cpEGFP	EFG	cpEGFP
GAL4	EFG	GAL4
GCaMP	EFG	GCaMP

Mapping

Hotz et al., 2021 ZDB-PUB-211101-7 PMID:34716961

Loss of glutamate transporter eaat2a leads to aberrant neuronal excitability, recurrent epileptic seizures, and basal hypoactivity

Hotz et al., 2021

ZDB-PUB-211101-7
PMID:34716961