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

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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; Duarte, Carlos B.

In: Molecular Neurobiology, Vol. 53, No. 6, 01.08.2016, p. 3513-3527.

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Costa, João T. ; Mele, Miranda ; Baptista, Márcio S. ; Gomes, João R. ; Ruscher, Karsten ; Nobre, Rui J. ; de Almeida, Luís Pereira ; Wieloch, Tadeusz ; Duarte, Carlos B. / Gephyrin Cleavage in In Vitro Brain Ischemia Decreases GABAA Receptor Clustering and Contributes to Neuronal Death. In: Molecular Neurobiology. 2016 ; Vol. 53, No. 6. pp. 3513-3527.

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TY - JOUR

T1 - Gephyrin Cleavage in In Vitro Brain Ischemia Decreases GABAA Receptor Clustering and Contributes to Neuronal Death

AU - Costa, João T.

AU - Mele, Miranda

AU - Baptista, Márcio S.

AU - Gomes, João R.

AU - Ruscher, Karsten

AU - Nobre, Rui J.

AU - de Almeida, Luís Pereira

AU - Wieloch, Tadeusz

AU - Duarte, Carlos B.

PY - 2016/8/1

Y1 - 2016/8/1

N2 - 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.

AB - 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.

KW - Brain ischemia

KW - Calpains

KW - Excitotoxicity

KW - GABAergic synapses

KW - Gephyrin

UR - http://www.scopus.com/inward/record.url?scp=84931863889&partnerID=8YFLogxK

U2 - 10.1007/s12035-015-9283-2

DO - 10.1007/s12035-015-9283-2

M3 - Article

C2 - 26093381

AN - SCOPUS:84931863889

VL - 53

SP - 3513

EP - 3527

JO - Molecular Neurobiology

JF - Molecular Neurobiology

SN - 1559-1182

IS - 6

ER -