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Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABA_A receptors.

ABSTRACT: ARFGEF1 encodes a guanine exchange factor involved in intracellular vesicle trafficking, and is a candidate gene for childhood genetic epilepsies. To model ARFGEF1 haploinsufficiency observed in a recent Lennox Gastaut Syndrome patient, we studied a frameshift mutation (Arfgef1^fs) in mice. Arfgef1^fs/+ pups exhibit signs of developmental delay, and Arfgef1^fs/+ adults have a significantly decreased threshold to induced seizures but do not experience spontaneous seizures. Histologically, the Arfgef1^fs/+ brain exhibits a disruption in the apical lining of the dentate gyrus and altered spine morphology of deep layer neurons. In primary hippocampal neuron culture, dendritic surface and synaptic but not total GABA_A receptors (GABA_AR) are reduced in Arfgef1^fs/+ neurons with an accompanying decrease in the number of GABA_AR-containing recycling endosomes in cell body. Arfgef1^fs/+ neurons also display differences in the relative ratio of Arf6⁺:Rab11⁺:TrfR⁺ recycling endosomes. Although the GABA_AR-containing early endosomes in Arfgef1^fs/+ neurons are comparable to wildtype, Arfgef1^fs/+ neurons show an increase in the number of GABA_AR-containing lysosomes in dendrite and cell body. Together, the altered endosome composition and decreased neuronal surface GABA_AR results suggests a mechanism whereby impaired neuronal inhibition leads to seizure susceptibility.

SUBMITTER: Teoh J

PROVIDER: S-EPMC6980672 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABAA receptors.

Teoh JiaJie J Subramanian Narayan N Pero Maria Elena ME Bartolini Francesca F Amador Ariadna A Kanber Ayla A Williams Damian D Petri Sabrina S Yang Mu M Allen Andrew S AS Beal Jules J Haut Sheryl R SR Frankel Wayne N WN

Neurobiology of disease 20191031

ARFGEF1 encodes a guanine exchange factor involved in intracellular vesicle trafficking, and is a candidate gene for childhood genetic epilepsies. To model ARFGEF1 haploinsufficiency observed in a recent Lennox Gastaut Syndrome patient, we studied a frameshift mutation (Arfgef1fs) in mice. Arfgef1fs/+ pups exhibit signs of developmental delay, and Arfgef1fs/+ adults have a significantly decreased threshold to induced seizures but do not experience spontaneous sei ...[more]

PMID: 31678406

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Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABA_A receptors.

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Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABA<sub>A</sub> receptors.

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