Poster Presentation 2014 International Biophysics Congress

Physiological properties of glycinergic synapses with defined subunit compositions (#592)

Yan Zhang 1 , Christine L. Dixon 1 , Joe W. Lynch 1
  1. Queensland Brain Institute, University of Queensland, St Lucia, QLD, Australia

Glycine receptors (GlyRs) mediate inhibitory neurotransmission in the spinal cord and disruptions to their function underlies a range of neurological disorders. A total of 4 subunits (α1, α2, α3 and β) are known to exist. To understand the physiological and pathological roles of GlyRs, it is important to understand the differences in the physiological and pharmacological properties of different GlyR isoforms. Furthermore, by understanding how hyperekplexia mutations affect the glycinergic synaptic function, it may be possible to select drugs that modify mutant GlyRs in appropriate ways. We developed a new preparation whereby a synapse of defined GlyR subunit composition can be formed between a spinal neuron and a HEK cell expressing the GlyR subunits of interest. This cannot be achieved in native neural tissue as the synaptic GlyR subunit composition cannot be controlled. We characterized the kinetic properties of wild-type GlyR α1-3 homomers and αβ heteromers and, also of the α1 subunit hyperekplexia mutations D80A and A52S. The α2β GlyR exhibited slow decay kinetics whereas α1β and α3β GlyRs exhibited identical fast synaptic kinetics. The β subunit has no significant effect on α1 GlyR postsynaptic localization but is indispensable for α2 and α3 GlyR postsynaptic clustering. Our recordings from α1A52Sβ and α1D80Aβ cells indicate impaired glycinergic transmission consistent with previous recordings from GlyR α1 mutant mice with hyperekplexia and spasmodic phenotypes, which validates artificial synapse as a model system to study receptor targeting and understand how glycinergic transmission is disrupted in different hyperekplexia phenotypes.