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

TY - JOUR

T1 - Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation

AU - Milanos, Sinem

AU - Kuenzel, Katharina

AU - Gilbert, Daniel F

AU - Janzen, Dieter

AU - Sasi, Manju

AU - Buettner, Andrea

AU - Frimurer, Thomas M.

AU - Villmann, Carmen

PY - 2018

Y1 - 2018

N2 - GABAA receptors are ligand-gated anion channels that form pentameric arrangements of various subunits. Positive allosteric modulators of GABAA receptors have been reported either isolated from plants or synthesized analogs of known GABAA receptor targeting drugs. Recently, we identified monoterpenes, e.g. myrtenol as positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in 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 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.

AB - GABAA receptors are ligand-gated anion channels that form pentameric arrangements of various subunits. Positive allosteric modulators of GABAA receptors have been reported either isolated from plants or synthesized analogs of known GABAA receptor targeting drugs. Recently, we identified monoterpenes, e.g. myrtenol as positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in 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 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.

KW - Journal Article

KW - virtual screening

KW - patch clamp recording

KW - myrtenol

KW - YFPI152L

KW - GABA receptor

KW - allosteric modulation

KW - GABA(A) receptor

U2 - 10.1515/hsz-2017-0262

DO - 10.1515/hsz-2017-0262

M3 - Journal article

C2 - 29408795

SN - 1431-6730

VL - 399

SP - 549

EP - 563

JO - Biological Chemistry

JF - Biological Chemistry

IS - 6

ER -