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Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation

  • Sinem Milanos , Katharina Kuenzel , Daniel F. Gilbert , Dieter Janzen , Manju Sasi , Andrea Buettner , Thomas M. Frimurer and Carmen Villmann EMAIL logo
Published/Copyright: February 6, 2018
Biological Chemistry
From the journal Biological Chemistry Volume 399 Issue 6

Abstract

GABAA receptors are ligand-gated anion channels that form pentameric arrangements of various subunits. Positive allosteric modulators of GABAA receptors have been reported as being isolated either from plants or synthesized analogs of known GABAA receptor targeting drugs. Recently, we identified monoterpenes, e.g. myrtenol as a positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in the loss of modulatory activity. Two independent approaches, fluorescence-based compound analysis and electrophysiological recordings in whole-cell configurations were used for analysis of transfected cells. C-atoms 1 and 2 of the myrtenol backbone were identified as crucial to preserve positive allosteric potential. A modification at C-atom 2 and lack of the hydroxyl group at C-atom 1 exhibited significantly reduced GABAergic currents at α1β2, α1β2γ, α2β3, α2β3γ and α4β3δ receptors. This effect was independent of the γ2 subunit. A sub-screen with side chain length and volume differences at the C-atom 1 identified two compounds that inhibited GABAergic responses but without receptor subtype specificity. Our combined approach of pharmacophore-based virtual screening and functional readouts reveals that side chain modifications of the bridged six-membered ring structure of myrtenol are crucial for its modulatory potential at GABAA receptors.

Keywords: allosteric modulation; GABAA receptor; myrtenol; patch clamp recording; virtual screening; YFPI152L

Acknowledgments

We would like to thank Dr. Lampros Milanos for critical reading of the manuscript and his helpful comments. Gudrun Schell and Nadine Vornberger are highly acknowledged for their excellent technical assistance. This work was supported by DFG VI586 (C.V.), (Funder Id: 10.13039/501100001659) and the Staedtler Stiftung (D.F.G.). The Novo Nordisk Foundation Center for Basic Metabolic Research and the Novo Nordisk Foundation Center for Protein Research (NNF14CC0001) are supported by an unconditional grant from the Novo Nordisk Foundation to the University of Copenhagen.

  1. Conflict of interest statement: The authors state that there is no conflict of interest.

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Supplemental Material:

The online version of this article offers supplementary material (https://doi.org/10.1515/hsz-2017-0262).

Received: 2017-10-4
Accepted: 2018-1-24
Published Online: 2018-2-6
Published in Print: 2018-5-24

©2018 Walter de Gruyter GmbH, Berlin/Boston

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https://doi.org/10.1515/hsz-2017-0262
Keywords for this article
allosteric modulation; GABAA receptor; myrtenol; patch clamp recording; virtual screening; YFPI152L

Articles in the same Issue

  1. Frontmatter
  2. Reviews
  3. Hodgkin lymphoma cell lines: to separate the wheat from the chaff
  4. The AGO proteins: an overview
  5. Research Articles/Short Communications
  6. Protein Structure and Function
  7. Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation
  8. The two major glucokinase isoforms show conserved functionality in β-cells despite different subcellular distribution
  9. Functional characterization of the mouse Serpina1 paralog DOM-7
  10. Cell Biology and Signaling
  11. CD45RO regulates the HIV-1 gp120-mediated apoptosis of T cells by activating Lck
  12. Silencing of MED27 inhibits adrenal cortical carcinogenesis by targeting the Wnt/β-catenin signaling pathway and the epithelial-mesenchymal transition process
  13. HDAC1 knockdown inhibits invasion and induces apoptosis in non-small cell lung cancer cells
  14. Hepatitis B virus X protein promotes proliferation of hepatocellular carcinoma cells by upregulating miR-181b by targeting ING5
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