Advanced

Gephyrin Cleavage in In Vitro Brain Ischemia Decreases GABAA Receptor Clustering and Contributes to Neuronal Death

Costa, João T.; Mele, Miranda; Baptista, Márcio S.; Gomes, João R.; Ruscher, Karsten; Nobre, Rui J.; de Almeida, Luís Pereira; Wieloch, Tadeusz LU and Duarte, Carlos B. (2016) In Molecular Neurobiology 53(6). p.3513-3527
Abstract

GABA (γ-aminobutyric acid) is the major inhibitory neurotransmitter in the central nervous system, and changes in GABAergic neurotransmission modulate the activity of neuronal networks. Gephyrin is a scaffold protein responsible for the traffic and synaptic anchoring of GABAA receptors (GABAAR); therefore, changes in gephyrin expression and oligomerization may affect the activity of GABAergic synapses. In this work, we investigated the changes in gephyrin protein levels during brain ischemia and in excitotoxic conditions, which may affect synaptic clustering of GABAAR. We found that gephyrin is cleaved by calpains following excitotoxic stimulation of hippocampal neurons with glutamate, as well as after... (More)

GABA (γ-aminobutyric acid) is the major inhibitory neurotransmitter in the central nervous system, and changes in GABAergic neurotransmission modulate the activity of neuronal networks. Gephyrin is a scaffold protein responsible for the traffic and synaptic anchoring of GABAA receptors (GABAAR); therefore, changes in gephyrin expression and oligomerization may affect the activity of GABAergic synapses. In this work, we investigated the changes in gephyrin protein levels during brain ischemia and in excitotoxic conditions, which may affect synaptic clustering of GABAAR. We found that gephyrin is cleaved by calpains following excitotoxic stimulation of hippocampal neurons with glutamate, as well as after intrahippocampal injection of kainate, giving rise to a stable cleavage product. Gephyrin cleavage was also observed in cultured hippocampal neurons subjected to transient oxygen-glucose deprivation (OGD), an in vitro model of brain ischemia, and after transient middle cerebral artery occlusion (MCAO) in mice, a model of focal brain ischemia. Furthermore, a truncated form of gephyrin decreased the synaptic clustering of the protein, reduced the synaptic pool of GABAAR containing γ2 subunits and upregulated OGD-induced cell death in hippocampal cultures. Our results show that excitotoxicity and brain ischemia downregulate full-length gephyrin with a concomitant generation of truncated products, which affect synaptic clustering of GABAAR and cell death.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Brain ischemia, Calpains, Excitotoxicity, GABAergic synapses, Gephyrin
in
Molecular Neurobiology
volume
53
issue
6
pages
15 pages
publisher
Humana Press
external identifiers
  • scopus:84931863889
  • wos:000379707600001
ISSN
0893-7648
DOI
10.1007/s12035-015-9283-2
language
English
LU publication?
yes
id
65c0ff7b-b204-43ca-aab9-29ca0ddddd04
date added to LUP
2016-10-05 15:01:34
date last changed
2017-03-05 04:36:54
@article{65c0ff7b-b204-43ca-aab9-29ca0ddddd04,
  abstract     = {<p>GABA (γ-aminobutyric acid) is the major inhibitory neurotransmitter in the central nervous system, and changes in GABAergic neurotransmission modulate the activity of neuronal networks. Gephyrin is a scaffold protein responsible for the traffic and synaptic anchoring of GABA<sub>A</sub> receptors (GABA<sub>A</sub>R); therefore, changes in gephyrin expression and oligomerization may affect the activity of GABAergic synapses. In this work, we investigated the changes in gephyrin protein levels during brain ischemia and in excitotoxic conditions, which may affect synaptic clustering of GABA<sub>A</sub>R. We found that gephyrin is cleaved by calpains following excitotoxic stimulation of hippocampal neurons with glutamate, as well as after intrahippocampal injection of kainate, giving rise to a stable cleavage product. Gephyrin cleavage was also observed in cultured hippocampal neurons subjected to transient oxygen-glucose deprivation (OGD), an in vitro model of brain ischemia, and after transient middle cerebral artery occlusion (MCAO) in mice, a model of focal brain ischemia. Furthermore, a truncated form of gephyrin decreased the synaptic clustering of the protein, reduced the synaptic pool of GABA<sub>A</sub>R containing γ2 subunits and upregulated OGD-induced cell death in hippocampal cultures. Our results show that excitotoxicity and brain ischemia downregulate full-length gephyrin with a concomitant generation of truncated products, which affect synaptic clustering of GABA<sub>A</sub>R and cell death.</p>},
  author       = {Costa, João T. and Mele, Miranda and Baptista, Márcio S. and Gomes, João R. and Ruscher, Karsten and Nobre, Rui J. and de Almeida, Luís Pereira and Wieloch, Tadeusz and Duarte, Carlos B.},
  issn         = {0893-7648},
  keyword      = {Brain ischemia,Calpains,Excitotoxicity,GABAergic synapses,Gephyrin},
  language     = {eng},
  month        = {08},
  number       = {6},
  pages        = {3513--3527},
  publisher    = {Humana Press},
  series       = {Molecular Neurobiology},
  title        = {Gephyrin Cleavage in In Vitro Brain Ischemia Decreases GABA<sub>A</sub> Receptor Clustering and Contributes to Neuronal Death},
  url          = {http://dx.doi.org/10.1007/s12035-015-9283-2},
  volume       = {53},
  year         = {2016},
}