title: GABA(A) receptors can initiate the formation of functional inhibitory GABAergic synapses.
abstract: 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 (GABAA Rs) 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-GABAA Rs, 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 GABAA Rs, suggesting a cooperative relationship between these proteins. Thus, in addition to fulfilling an essential functional role, postsynaptic GABAA Rs can promote the adhesion of inhibitory axons and the development of functional synapses.
authors.affiliation: UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London, WC1N 1AX, UK.
authors.forename: Celine
authors.initials: C
authors.lastname: Fuchs
authors.forename: Karine
authors.initials: K
authors.lastname: Abitbol
authors.forename: Jemima J
authors.initials: JJ
authors.lastname: Burden
authors.forename: Audrey
authors.initials: A
authors.lastname: Mercer
authors.forename: Laura
authors.initials: L
authors.lastname: Brown
authors.forename: Jonathan
authors.initials: J
authors.lastname: Iball
authors.forename: F
authors.initials: F
authors.lastname: Anne Stephenson
authors.forename: Alex M
authors.initials: AM
authors.lastname: Thomson
authors.forename: Jasmina N
authors.initials: JN
authors.lastname: Jovanovic
mesh_terms: D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000378:metabolism / Q000502:physiology*; D001479:Basal Ganglia / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D048708:Cell Growth Processes; D059330:GABAergic Neurons / Q000378:metabolism / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D009419:Nerve Tissue Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D055366:Synaptic Potentials
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D009419:Nerve Tissue Proteins; D011963:Receptors, GABA-A; C098003:neuroligin 2
keywords: inhibition; neuroligin-2; postsynaptic; presynaptic; synaptic adhesion; synaptogenesis
references.citation: Proc Natl Acad Sci U S A. 1996 Oct 15;93(21):11939-44
references.pmid: 8876241
references.citation: Neuron. 2009 Sep 10;63(5):628-42
references.pmid: 19755106
references.citation: Cell. 2004 Dec 29;119(7):1013-26
references.pmid: 15620359
references.citation: Neuron. 2010 May 13;66(3):403-16
references.pmid: 20471353
references.citation: Neuron. 2006 Sep 21;51(6):741-54
references.pmid: 16982420
references.citation: J Biol Chem. 2012 Aug 10;287(33):27417-30
references.pmid: 22711532
references.citation: Prog Brain Res. 2007;160:59-87
references.pmid: 17499109
references.citation: Adv Pharmacol. 2006;54:231-63
references.pmid: 17175817
references.citation: Science. 2005 Feb 25;307(5713):1324-8
references.pmid: 15681343
references.citation: Mol Cell Neurosci. 2009 Sep;42(1):45-55
references.pmid: 19463950
references.citation: Mol Cell Neurosci. 2007 May;35(1):14-23
references.pmid: 17336090
references.citation: Nat Protoc. 2007;2(12):3090-101
references.pmid: 18079708
references.citation: Curr Opin Neurobiol. 2011 Feb;21(1):132-43
references.pmid: 20832286
references.citation: Nat Neurosci. 2006 May;9(5):642-9
references.pmid: 16582905
references.citation: Annu Rev Neurosci. 2010;33:473-507
references.pmid: 20367446
references.citation: J Biol Chem. 2011 Jun 24;286(25):22456-68
references.pmid: 21540179
references.citation: Neuron. 2007 Jun 21;54(6):919-31
references.pmid: 17582332
references.citation: Eur J Neurosci. 2000 Feb;12(2):425-36
references.pmid: 10712623
references.citation: Eur J Neurosci. 2011 Mar;33(5):868-78
references.pmid: 21219474
references.citation: J Microsc. 2005 Apr;218(Pt 1):52-61
references.pmid: 15817063
references.citation: Cell Mol Life Sci. 2012 Aug;69(15):2485-99
references.pmid: 22314501
references.citation: J Comp Neurol. 1995 Aug 14;359(1):154-94
references.pmid: 8557845
references.citation: J Neurosci. 2010 Feb 24;30(8):2935-50
references.pmid: 20181591
references.citation: J Comp Neurol. 2000 Jan 10;416(2):158-72
references.pmid: 10581463
references.citation: Neuron. 2006 Jul 20;51(2):179-86
references.pmid: 16846853
references.citation: J Neurosci. 2005 Apr 27;25(17):4330-42
references.pmid: 15858059
references.citation: J Neurosci. 2009 Nov 4;29(44):13883-97
references.pmid: 19889999
references.citation: Nat Neurosci. 2000 Jan;3(1):22-9
references.pmid: 10607391
references.citation: J Biol Chem. 1994 Sep 30;269(39):24403-9
references.pmid: 7929101
references.citation: J Neurosci. 2013 Feb 20;33(8):3612-23
references.pmid: 23426688
references.citation: Nature. 2003 Jun 26;423(6943):939-48
references.pmid: 12827191
references.citation: Nature. 1987 Jul 16-22;328(6127):221-7
references.pmid: 3037384
references.citation: Genes Brain Behav. 2009 Feb;8(1):114-26
references.pmid: 19016888
references.citation: Nature. 2008 Oct 16;455(7215):903-11
references.pmid: 18923512
references.citation: Cell. 2000 Jun 9;101(6):657-69
references.pmid: 10892652
references.citation: Nat Neurosci. 2003 Jul;6(7):708-16
references.pmid: 12796785
references.citation: Eur J Neurosci. 2001 Feb;13(3):428-42
references.pmid: 11168550
references.citation: J Physiol. 2011 Oct 15;589(Pt 20):4959-80
references.pmid: 21825022
references.citation: J Biol Chem. 2008 Jan 25;283(4):2323-34
references.pmid: 18006501