GABAA受体(γ-氨基丁酸门控受体A型;GABAAR),哺乳动物大脑中抑制性突触的主要结构和功能突触后成分,属于GABA门控Cl-/HCO3-离子通道家族。它们被组装为来自一个亚基家族的异源四聚体,包括:α(1-6),β(1-3),γ(1-3),δ,ε,π,θ和ρ(1-3)。GABAAR与突触后粘附蛋白Neuroligin2(NL2)和许多其他突触前和突触后蛋白一起指导抑制性GABA能突触的启动和功能成熟。这项研究检查了GABAAR和NL2如何相互作用以启动突触的形成。两种功能不同的GABAAR亚型,突触型α2β2γ2-GABAAR与突触外型α4β3δ-GABAAR在HEK293细胞中单独表达或与NL2一起表达,并与纹状体GABA能培养基多刺神经元共培养,以使GABAergic轴突能神经支配HEK293细胞。当单独表达时,只有突触α2β2γ2-GABAAR诱导HEK293细胞的神经支配。然而,当GABAAR与NL2共表达时,对突触形成的影响超过了这些蛋白质的个体作用,表明协同相互作用,α2β2γ2-GABAAR/NL2显示出比α4β3δ-GABAAR/NL2或单独的NL2显著更大的突触形成活性。为了研究这种相互作用的分子基础,GABAAR亚基和NL2的不同组合共表达,神经支配和突触活动的程度评估,揭示了γ2亚基的关键作用。在生化分析中,建立了NL2与α2β2γ2-GABAAR之间的相互作用,并将其定位到γ2亚基的大细胞内结构域。
GABAA receptors (γ-aminobutyric acid-gated receptors type A; GABAARs), the major structural and functional postsynaptic components of inhibitory synapses in the mammalian brain, belong to a family of GABA-gated Cl-/HCO3 - ion channels. They are assembled as heteropentamers from a family of subunits including: α (1-6), β(1-3), γ(1-3), δ, ε, π, θ and ρ(1-3). GABAARs together with the postsynaptic adhesion protein Neuroligin 2 (NL2) and many other pre- and post-synaptic proteins guide the initiation and functional maturation of inhibitory GABAergic synapses. This study examined how GABAARs and NL2 interact with each other to initiate the formation of synapses. Two functionally distinct GABAAR subtypes, the synaptic type α2β2γ2-GABAARs versus extrasynaptic type α4β3δ-GABAARs were expressed in HEK293 cells alone or together with NL2 and co-cultured with striatal GABAergic medium spiny neurons to enable innervation of HEK293 cells by GABAergic axons. When expressed alone, only the synaptic α2β2γ2-GABAARs induced innervation of HEK293 cells. However, when GABAARs were co-expressed with NL2, the effect on synapse formation exceeded the individual effects of these proteins indicating a synergistic interaction, with α2β2γ2-GABAAR/NL2 showing a significantly greater synaptogenic activity than α4β3δ-GABAAR/NL2 or NL2 alone. To investigate the molecular basis of this interaction, different combinations of GABAAR subunits and NL2 were co-expressed, and the degree of innervation and synaptic activity assessed, revealing a key role of the γ2 subunit. In biochemical assays, the interaction between NL2 and α2β2γ2-GABAAR was established and mapped to the large intracellular domain of the γ2 subunit.