C.F. and K.A. contributed equally to this work.
GABAA receptors can initiate the formation of functional inhibitory GABAergic synapses
Article first published online: 5 AUG 2013
© 2013 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
European Journal of Neuroscience
Volume 38, Issue 8, pages 3146–3158, October 2013
How to Cite
Fuchs, C., Abitbol, K., Burden, J. J., Mercer, A., Brown, L., Iball, J., Anne Stephenson, F., Thomson, A. M. and Jovanovic, J. N. (2013), GABAA receptors can initiate the formation of functional inhibitory GABAergic synapses. European Journal of Neuroscience, 38: 3146–3158. doi: 10.1111/ejn.12331
- Issue published online: 20 OCT 2013
- Article first published online: 5 AUG 2013
- Manuscript Accepted: 8 JUL 2013
- Manuscript Revised: 3 JUL 2013
- Manuscript Received: 30 APR 2013
- MRC. Grant Number: G0800498
- synaptic adhesion;
The mechanisms that underlie the selection of an inhibitory GABAergic axon's postsynaptic targets and the formation of the first contacts are currently unknown. To determine whether expression of GABAA receptors (GABAARs) themselves – the essential functional postsynaptic components of GABAergic synapses – can be sufficient to initiate formation of synaptic contacts, a novel co-culture system was devised. In this system, the presynaptic GABAergic axons originated from embryonic rat basal ganglia medium spiny neurones, whereas their most prevalent postsynaptic targets, i.e. α1/β2/γ2-GABAARs, were expressed constitutively in a stably transfected human embryonic kidney 293 (HEK293) cell line. The first synapse-like contacts in these co-cultures were detected by colocalization of presynaptic and postsynaptic markers within 2 h. The number of contacts reached a plateau at 24 h. These contacts were stable, as assessed by live cell imaging; they were active, as determined by uptake of a fluorescently labelled synaptotagmin vesicle-luminal domain-specific antibody; and they supported spontaneous and action potential-driven postsynaptic GABAergic currents. Ultrastructural analysis confirmed the presence of characteristics typical of active synapses. Synapse formation was not observed with control or N-methyl-d-aspartate receptor-expressing HEK293 cells. A prominent increase in synapse formation and strength was observed when neuroligin-2 was co-expressed with GABAARs, suggesting a cooperative relationship between these proteins. Thus, in addition to fulfilling an essential functional role, postsynaptic GABAARs can promote the adhesion of inhibitory axons and the development of functional synapses.