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γ-aminobutyric acid type A (GABAA) receptor subunits play a direct structural role in synaptic contact formation via their N-terminal extracellular domains

Brown, LE; Nicholson, MW; Arama, JE; Mercer, A; Thomson, AM; Jovanovic, JN; (2016) γ-aminobutyric acid type A (GABAA) receptor subunits play a direct structural role in synaptic contact formation via their N-terminal extracellular domains. The Journal of Biological Chemistry , 291 (27) pp. 13926-13942. 10.1074/jbc.M116.714790. Green open access

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Abstract

The establishment of cell-cell contacts between presynaptic GABAergic neurons and their postsynaptic targets initiates the process of GABAergic synapse formation. GABAA receptors (GABAARs), the main postsynaptic receptors for GABA, have been recently demonstrated to act as synaptogenic proteins that can single-handedly induce the formation and functional maturation of inhibitory synapses. To establish how the subunit composition of GABAARs influences their ability to induce synaptogenesis, a co-culture model system incorporating GABAergic medium spiny neurons (MSNs) and the HEK293 cells, stably expressing different combinations of receptor subunits, was developed. Analyses of HEK293 cells innervation by MSN axons using immunocytochemistry, activity-dependent labeling and electrophysiology have indicated that γ2 subunit is required for the formation of active synapses and that its effects are influenced by the type of α/β subunits incorporated into the functional receptor. To further characterize this process, the large N-terminal extracellular domains (ECDs) of α1, α2, β2 and γ2 subunits were purified using baculovirus/Sf9 cell system. When these proteins were applied to the co-cultures of MSNs and α1/β2/γ2-expressing HEK293 cells, the α1, β2 or γ2 ECD each caused a significant reduction in contact formation, in contrast to the α2 ECD which had no effect. Together, our experiments indicate that the structural role of GABAARs in synaptic contact formation is determined by their subunit composition, with the N-terminal ECDs of each of the subunits directly participating in interactions between the presynaptic and postsynaptic elements, suggesting the these interactions are multivalent and specific.

Type: Article
Title: γ-aminobutyric acid type A (GABAA) receptor subunits play a direct structural role in synaptic contact formation via their N-terminal extracellular domains
Open access status: An open access version is available from UCL Discovery
DOI: 10.1074/jbc.M116.714790
Publisher version: http://dx.doi.org/10.1074/jbc.M116.714790
Language: English
Additional information: This research was originally published in The Journal of Biological Chemistry. Brown, LE; Nicholson, MW; Arama, JE; Mercer, A; Thomson, AM; Jovanovic, JN; γ-Aminobutyric Acid Type A (GABAA) Receptor Subunits Play a Direct Structural Role in Synaptic Contact Formation via Their N-terminal Extracellular Domains. The Journal of Biological Chemistry. 2016; Vol: 291(27) pp 13926-pp. 13942 © the American Society for Biochemistry and Molecular Biology. Final version free via Creative Commons CC-BY license.
Keywords: Cell culture, gamma-aminobutyric acid (GABA), inhibition mechanism, protein domain, synapse
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy > Pharmacology
URI: http://discovery.ucl.ac.uk/id/eprint/1488566
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