Site-specific effects of neurosteroids on GABAA receptor activation and desensitization
- Washington University in St Louis, United States
Abstract
This study examines how site-specific binding to three identified neurosteroid binding sites in the α1β3 GABAA receptor (GABAAR) contributes to neurosteroid allosteric modulation. We found that the potentiating neurosteroid, allopregnanolone, but not its inhibitory 3β-epimer epi-allopregnanolone, binds to the canonical β3(+)–α1(-) intersubunit site that mediates receptor activation by neurosteroids. In contrast, both allopregnanolone and epi-allopregnanolone bind to intrasubunit sites in the β3 subunit, promoting receptor desensitization and the α1 subunit promoting effects that vary between neurosteroids. Two neurosteroid analogues with diazirine moieties replacing the 3-hydroxyl (KK148 and KK150) bind to all three sites, but do not potentiate GABAAR currents. KK148 is a desensitizing agent, whereas KK150 is devoid of allosteric activity. These compounds provide potential chemical scaffolds for neurosteroid antagonists. Collectively, these data show that differential occupancy and efficacy at three discrete neurosteroid binding sites determine whether a neurosteroid has potentiating, inhibitory, or competitive antagonist activity on GABAARs.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Funding
National Institutes of Health (2R01GM108799-05)
- Alex S Evers
National Institutes of Health (2R01GM108799-05)
- Douglas F Covey
National Institutes of Health (5K08GM126336-03)
- Wayland WL Cheng
National Institutes of Health (5R01GM108580-06)
- Gustav Akk
Taylor Family Institute for Innovative Psychiatric Research
- Alex S Evers
Taylor Family Institute for Innovative Psychiatric Research
- Gustav Akk
Taylor Family Institute for Innovative Psychiatric Research
- Douglas F Covey
Taylor Family Institute for Innovative Psychiatric Research
- David E Reichert
Taylor Family Institute for Innovative Psychiatric Research
- Zi-Wei Chen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Sugasawa et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Site-specific effects of neurosteroids on GABAA receptor activation and desensitization
eLife 9:e55331.
https://doi.org/10.7554/eLife.55331
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