| First Author | Brown LE | Year | 2016 |
| Journal | J Biol Chem | Volume | 291 |
| Issue | 27 | Pages | 13926-42 |
| PubMed ID | 27129275 | Mgi Jnum | J:281261 |
| Mgi Id | MGI:6208009 | Doi | 10.1074/jbc.M116.714790 |
| Citation | Brown LE, et al. (2016) gamma-Aminobutyric Acid Type A (GABAA) Receptor Subunits Play a Direct Structural Role in Synaptic Contact Formation via Their N-terminal Extracellular Domains. J Biol Chem 291(27):13926-42 |
| abstractText | 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 and the HEK293 cells, stably expressing different combinations of receptor subunits, was developed. Analyses of HEK293 cell innervation by medium spiny neuron axons using immunocytochemistry, activity-dependent labeling, and electrophysiology have indicated that the gamma2 subunit is required for the formation of active synapses and that its effects are influenced by the type of alpha/beta subunits incorporated into the functional receptor. To further characterize this process, the large N-terminal extracellular domains (ECDs) of alpha1, alpha2, beta2, and gamma2 subunits were purified using the baculovirus/Sf9 cell system. When these proteins were applied to the co-cultures of MSNs and alpha1/beta2/gamma2-expressing HEK293 cells, the alpha1, beta2, or gamma2 ECD each caused a significant reduction in contact formation, in contrast to the alpha2 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. |
