Correlating Structural and Energetic Changes in Glycine Receptor Activation

Scott, Suzanne; Lynch, Joseph W.; Keramidas, Angelo

doi:10.1074/jbc.m114.616573

Cited by 26 publications

(47 citation statements)

References 51 publications

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“…The I43F mutation resulted in prolonged bursts of spontaneous channel activity (Fig. 3E) similar to that previously demonstrated for the Q226E mutation (24).…”

Section: Summary Of Results -We Have Identified Two New Glra1 Gain-ofsupporting

confidence: 64%

“…The mean single channel amplitude measured at -70 mV was 3.31 ± 0.06 pA (n = 4), yielding a conductance of 41.6 ± 0.7 pS. This is similar to that of 45.9 ± 1.4 pS for wild type receptors (24) and suggests that the a1 W170S mutation has no appreciable effect on conductance.…”

Section: W170ssupporting

confidence: 59%

“…This yielded an open frequency of 0.2 Hz per channel. Wild-type a1b GlyRs under the similar recording conditions exhibit negligible spontaneous activity (10,(24)(25)(26).…”

Section: W170smentioning

confidence: 99%

“…The V280M mutation significantly reduced both the glycine EC 50 and the I max values, although the W170S, Q226E and R414H mutations had little effect of these parameters (16,19). The Q226E, V280M and R414H mutations have previously been shown to induce spontaneous single channel activity (16,24). In this study we filled in the gaps by quantifying the glycine EC 50 and I max values of a1…”

Section: Properties Of Glyrs Measured By Whole Cell Recording -mentioning

confidence: 99%

“…We have previously demonstrated that channel activation is facilitated by an energetic interaction between these residues (10,24). This interaction is strengthened by the Q226E mutation, resulting in the longer active periods that underlie the gain-of-function startle phenotype (10,24). V280 is located in the M2-M3 loop (Fig.…”

Section: Molecular Mechanisms Of the Mutations -Q226mentioning

confidence: 99%

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Physiological properties of Glycinergic synapses with defined subunit compositions

Zhang¹

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Glycine receptors (GlyRs) mediate fast inhibitory neurotransmission in the spinal cord and brainstem. Four GlyR subunits (α1 -3, β) have been identified in humans, and their differential anatomical distributions result in a diversity of synaptic isoforms with unique physiological and pharmacological properties. However, despite their importance in controlling neuronal function, little is known about these properties. To address this, we developed an 'artificial' synapse system which allows to control over the synaptic GlyR subunit composition. We induced the formation of recombinant synapses between cultured spinal neurons and HEK293 cells expressing GlyR subunits of interest plus the synapse-promoting molecule, neuroligin-2A. In the heterosynapses thus formed, recombinant α1β and α3β GlyRs mediated fast decaying inhibitory postsynaptic currents (IPSCs) whereas α2β GlyRs mediated slow decaying IPSCs. These results are consistent with the fragmentary information available from native synapses and single channel kinetic studies. As β subunit incorporation is considered essential for localizing GlyRs at the synapse, we were surprised that α1 -3 homomers supported robust IPSCs with β subunit incorporation accelerating IPSC rise and decay times in α2β and α3β heteromers only. Finally, heterosynapses incorporating α1 D80A β and α1 A52S β GlyRs exhibited accelerated IPSC decay rates closely resembling those recorded in native synapses from mutant mice homozygous for these mutations, providing an additional validation of our technique. As our model system successfully recapitulates the effects of known GlyR disease mutations, we employed it to investigate the effects of new GlyR disease mutations.Hyperekplexia is a human neuromotor disorder caused by mutations that impair glycinergic neurotransmission. We investigated the mechanism by which gain-of-function GlyR mutations cause hyperekplexia. We identified two new gain-of-function mutations (I43F, W170S) and characterised these along with the known gain-of-function mutations (Q226E, V280M, R414H) to identify how they cause hyperekplexia. Using 'artificial' synapses, we show that all mutations prolong the decay of IPSCs and induce spontaneous activation. As these effects may deplete the chloride electrochemical gradient, hyperekplexia could potentially result from reduced glycinergic inhibitory efficacy. However, we consider this unlikely as it should also lead to pain sensitization and a hyperekplexia phenotype that correlates with mutation severity, neither of which is observed in patients. We also rule out small increases in IPSC decay times (as caused by W170S and R414H)as a possible mechanism given that the clinically-important drug, tropisetron, increases glycinergic IPSC decay times without causing motor side effects. A recent study concluded that an elevated intracellular chloride concentration late during development ablates α1β glycinergic synapses but iii spares GABAergic synapses. As this mechanism satisfies all our considerations, we propose it is pr...

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“…The I43F mutation resulted in prolonged bursts of spontaneous channel activity (Fig. 3E) similar to that previously demonstrated for the Q226E mutation (24).…”

Section: Summary Of Results -We Have Identified Two New Glra1 Gain-ofsupporting

confidence: 64%

Section: W170ssupporting

confidence: 59%

“…This yielded an open frequency of 0.2 Hz per channel. Wild-type a1b GlyRs under the similar recording conditions exhibit negligible spontaneous activity (10,(24)(25)(26).…”

Section: W170smentioning

confidence: 99%

Section: Properties Of Glyrs Measured By Whole Cell Recording -mentioning

confidence: 99%

Section: Molecular Mechanisms Of the Mutations -Q226mentioning

confidence: 99%

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Physiological properties of Glycinergic synapses with defined subunit compositions

Zhang¹

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The general anesthetic etomidate and fenamate mefenamic acid oppositely affect GABAAR and GlyR: a structural explanation

Rossokhin

2020

Eur Biophys J

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GABA and glycine act as inhibitory neurotransmitters in the CNS. Inhibitory neurotransmission is mediated via activation of ionotropic GABA A and glycine receptors. We used a modeling approach to explain the opposite effects of the general anesthetic etomidate (ETM) and fenamate mefenamic acid (MFA) on GABA-and glycine-activated currents recorded in isolated cerebellar Purkinje cells and hippocampal pyramidal neurons, respectively. These drugs potentiated GABA A Rs but blocked GlyRs. We built a homology model of α1β GlyR based on the cryo-EM structure of open α1 GlyR, used the α1β3γ2 GABA A R structure from the PDB, and applied Monte-Carlo energy minimization to optimize models of receptors and ligand-receptor complexes. In silico docking suggests that ETM/MFA bind at the transmembrane β(+)/α(−) intersubunit interface in GABA A R. Our models predict that the bulky side chain of the highly conserved Arg 19′ residue at the plus interface side wedges the interface and maintains the conducting receptor state. We hypothesized that MFA/ETM binding at the β(+)/α(−) interface leads to prolongation of receptor lifetime in the open state. Having analyzed different GABA A R and GlyR structures available in the PDB, we found that mutual arrangement of the Arg 19′ and Gln −26′ side chains at the plus and minus interface sides, respectively, plays an important role when the receptor switches from the open to closed state. We show that this process is accompanied by narrowing of the intersubunit interfaces, leading to extrusion of the Arg 19′ side chain from the interface. Our models allow us to explain the lack of GlyR potentiation in our electrophysiological experiments.

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The Role of Autoantibodies to the Extracellular Regions of Ionotropic Receptors in the Etiology and Pathogenesis of Autoimmune Diseases

Zharova

Шпаков

2017

Neurosci Behav Physi

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Correlating Structural and Energetic Changes in Glycine Receptor Activation

Cited by 26 publications

References 51 publications

Physiological properties of Glycinergic synapses with defined subunit compositions

Physiological properties of Glycinergic synapses with defined subunit compositions

The general anesthetic etomidate and fenamate mefenamic acid oppositely affect GABAAR and GlyR: a structural explanation

The Role of Autoantibodies to the Extracellular Regions of Ionotropic Receptors in the Etiology and Pathogenesis of Autoimmune Diseases

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