TY - JOUR

T1 - A Novel Glycine Receptor Variant with Startle Disease Affects Syndapin I and Glycinergic Inhibition

AU - Langlhofer, Georg

AU - Schaefer, Natascha

AU - Maric, Hans M.

AU - Keramidas, Angelo

AU - Zhang, Yan

AU - Baumann, Peter

AU - Blum, Robert

AU - Breitinger, Ulrike

AU - Strømgaard, Kristian

AU - Schlosser, Andreas

AU - Kessels, Michael M.

AU - Koch, Dennis

AU - Qualmann, Britta

AU - Breitinger, Hans Georg

AU - Lynch, Joseph W.

AU - Villmann, Carmen

N1 - Publisher Copyright: Copyright © 2020 the authors

PY - 2020

Y1 - 2020

N2 - Glycine receptors (GlyRs) are the major mediators of fast synaptic inhibition in the adult human spinal cord and brainstem. Hereditary mutations to GlyRs can lead to the rare, but potentially fatal, neuromotor disorder hyperekplexia. Most mutations located in the large intracellular domain (TM3-4 loop) of the GlyRa1 impair surface expression levels of the receptors. The novel GLRA1 mutation P366L, located in the TM3-4 loop, showed normal surface expression but reduced chloride currents, and accelerated whole-cell desensitization observed in whole-cell recordings. At the single-channel level, we observed reduced unitary conductance accompanied by spontaneous opening events in the absence of extracellular glycine. Using peptide microarrays and tandem MS-based analysis methods, we show that the proline-rich stretch surrounding P366 mediates binding to syndapin I, an F-BAR domain protein involved in membrane remodeling. The disruption of the noncanonical Src homology 3 recognition motif by P366L reduces syndapin I binding. These data suggest that the GlyRa1 subunit interacts with intracellular binding partners and may therefore play a role in receptor trafficking or synaptic anchoring, a function thus far only ascribed to the GlyRb subunit. Hence, the P366L GlyRa1 variant exhibits a unique set of properties that cumulatively affect GlyR functionality and thus might explain the neuropathological mechanism underlying hyperekplexia in the mutant carriers. P366L is the first dominant GLRA1 mutation identified within the GlyRa1 TM3-4 loop that affects GlyR physiology without altering protein expression at the whole-cell and surface levels.

AB - Glycine receptors (GlyRs) are the major mediators of fast synaptic inhibition in the adult human spinal cord and brainstem. Hereditary mutations to GlyRs can lead to the rare, but potentially fatal, neuromotor disorder hyperekplexia. Most mutations located in the large intracellular domain (TM3-4 loop) of the GlyRa1 impair surface expression levels of the receptors. The novel GLRA1 mutation P366L, located in the TM3-4 loop, showed normal surface expression but reduced chloride currents, and accelerated whole-cell desensitization observed in whole-cell recordings. At the single-channel level, we observed reduced unitary conductance accompanied by spontaneous opening events in the absence of extracellular glycine. Using peptide microarrays and tandem MS-based analysis methods, we show that the proline-rich stretch surrounding P366 mediates binding to syndapin I, an F-BAR domain protein involved in membrane remodeling. The disruption of the noncanonical Src homology 3 recognition motif by P366L reduces syndapin I binding. These data suggest that the GlyRa1 subunit interacts with intracellular binding partners and may therefore play a role in receptor trafficking or synaptic anchoring, a function thus far only ascribed to the GlyRb subunit. Hence, the P366L GlyRa1 variant exhibits a unique set of properties that cumulatively affect GlyR functionality and thus might explain the neuropathological mechanism underlying hyperekplexia in the mutant carriers. P366L is the first dominant GLRA1 mutation identified within the GlyRa1 TM3-4 loop that affects GlyR physiology without altering protein expression at the whole-cell and surface levels.

KW - Glycine receptor

KW - Hyperekplexia

KW - PPII helix

KW - Syndapin I

KW - TM3-4 loop

U2 - 10.1523/JNEUROSCI.2490-19.2020

DO - 10.1523/JNEUROSCI.2490-19.2020

M3 - Journal article

C2 - 32354853

AN - SCOPUS:85086747495

VL - 40

SP - 4954

EP - 4969

JO - The Journal of neuroscience : the official journal of the Society for Neuroscience

JF - The Journal of neuroscience : the official journal of the Society for Neuroscience

SN - 0270-6474

IS - 25

ER -