Agonist-dependent endocytosis of γ-aminobutyric acid type A (GABAA) receptors revealed by a γ2(R43Q) epilepsy mutation.
GABA-gated chloride channels (GABAARs) trafficking is involved in the regulation of fast inhibitory transmission. Here, we took advantage of a γ2(R43Q) subunit mutation linked to epilepsy in humans that considerably reduces the number of GABAARs on the cell surface to better understand the trafficking of GABAARs. Using recombinant expression in cultured rat hippocampal neurons and COS-7 cells, we showed that receptors containing γ2(R43Q) were addressed to the cell membrane but underwent clathrin-mediated dynamin-dependent endocytosis. The γ2(R43Q)-dependent endocytosis was reduced by GABAAR antagonists. These data, in addition to a new homology model, suggested that a conformational change in the extracellular domain of γ2(R43Q)-containing GABAARs increased their internalization. This led us to show that endogenous and recombinant wild-type GABAAR endocytosis in both cultured neurons and COS-7 cells can be amplified by their agonists. These findings revealed not only a direct relationship between endocytosis of GABAARs and a genetic neurological disorder but also that trafficking of these receptors can be modulated by their agonist.
From the Université Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), UMR 5287, F-33000 Bordeaux, France.
Severine
S
Chaumont
Caroline
C
André
David
D
Perrais
Eric
E
Boué-Grabot
Antoine
A
Taly
Maurice
M
Garret
D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D004705:Endocytosis; D004827:Epilepsy / Q000235:genetics*; D058785:GABA-A Receptor Agonists / Q000494:pharmacology*; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology / Q000196:embryology; D006801:Humans; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D009422:Nervous System Diseases / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*; D009435:Synaptic Transmission
D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A
GABA Receptors; Neurobiology; Neurological Diseases; Receptor Endocytosis; Trafficking