Defined concatenated α6α1β3γ2 GABAA receptor constructs reveal dual action of pyrazoloquinolinone allosteric modulators

Simeone, Xenia; Iorio, M.T.; Siebert, David Chan Bodin; Rehman, Sabah; Schnürch, Michael; Mihovilovič, Marko D.; Ernst, Margot

doi:10.1016/j.bmc.2019.06.006

Cited by 13 publications

(13 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have previously demonstrated that β-isoform-selective ligands can in principle be developed for this site (Simeone et al, 2017 ). We also have demonstrated that ligands which modulate via the α+/β− ECD interfaces can differentiate between α6+/β3− and α1+/β3− (Simeone et al, 2019 ). To take advantage of these alternative interfaces for selective targeting it would thus be of interest to identify the β-isoforms, which are between the two α subunits in the receptors described here.…”

Section: Discussionmentioning

confidence: 95%

“…The receptors identified in this study could also be discriminated via their β-subunits, which may potentially differ in those receptor subtypes. Little is known about the alternative modulatory site which is present at the extracellular α+/β- interface (Ramerstorfer et al, 2011 ; Varagic et al, 2013a , b ; Simeone et al, 2019 ). We have previously demonstrated that β-isoform-selective ligands can in principle be developed for this site (Simeone et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum

Scholze

Pökl

Längle

et al. 2020

Front. Synaptic Neurosci.

View full text Add to dashboard Cite

GABAA receptors are pentameric GABA-gated chloride channels. The existence of 19 different subunits (six α, three β, three γ, δ, ε, θ, π, and three ρ) in mammalian systems gives rise to an enormous theoretical diversity of GABAA receptor subtypes with distinct subunit composition and unique pharmacological properties. These receptors are already now the drug targets of several clinically used compounds, such as benzodiazepines, anesthetics, and many more. There is a constant quest to identify novel molecules and possible future drug targets: Currently, α6-containing GABAA receptors are being discussed in the context of treating sensorimotor gating deficits in neuropsychiatric disorders, such as tic disorders and schizophrenia. Therefore, we aim to learn more about α6-containing GABAA receptors. They are mostly expressed in the cerebellar granule cell layer, where they form the following subtypes: α6βxγ2, α1α6βxγ2, α6βxδ, and α1α6βxδ. In former studies, α1α6βxγ2-containing GABAA receptors were considered a single receptor population. In the current study, we investigate the possibility, that this population can consist of two subgroups with alternative arrangements depending if α1 neighbors γ2 (forming a “diazepam-sensitive” receptor), or if α6 neighbors γ2 (forming a “diazepam-insensitive” receptor) and aimed to prove the existence of both subtypes in native tissue. We performed immunoprecipitation experiments on rat cerebellar lysates using α1- or α6 subunit-specific antibodies followed by radioligand binding assays with either 3 H-flunitrazepam or 3 H-Ro 15-4513. Indeed, we were able to prove the existence of two distinct populations of α1α6-containing GABAA-receptors and could quantify the different receptor populations: α1βxγ2 receptors constitute approximately 60% of all γ2-containing receptors in the rat cerebellum, α6βxγ2 about 20%, and both isoforms of α1α6βxγ2 9–15% each. The simple classification of GABAA-receptors into αx-containing subtypes seems not to reflect the complexity of nature; those receptors are more diverse than previously thought.

show abstract

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum

Scholze

Pökl

Längle

et al. 2020

Front. Synaptic Neurosci.

View full text Add to dashboard Cite

show abstract

“…Since pyrazoloquinolinones, such as Compound 6 and DK-I-56-1, modulate α6GABA A Rs by binding at the α6 + βinterface [17], they not only modulate α6βγ2 but also α6βδ receptors, although to a smaller extent [52,68,69]. And probably they will also modulate other α6GABA A Rs containing an α6+β-interface.…”

Section: Tg α6gaba a Rs As A Novel Therapeutic Target For Migrainementioning

confidence: 99%

α6GABAA Receptor Positive Modulators Alleviate Migraine-like Grimaces in Mice via Compensating GABAergic Deficits in Trigeminal Ganglia

et al. 2021

View full text Add to dashboard Cite

Migraine is caused by hyperactivity of the trigeminovascular system, where trigeminal ganglia (TG) play an important role. This hyperactivity might originate from an underfunctional GABAergic system in TG. To investigate this possibility, we adapted a mouse model of migraine by inducing migraine-like grimaces in male mice via repeated injections of nitroglycerin (NTG, 10 mg/kg, i.p.), once every 2 days, for up to 5 sessions. Migraine-like facial pain scores were measured using the mouse grimace scale. Repeated NTG treatments in mice caused significant increases in migraine-like grimaces that were aborted and prevented by two anti-migraine agents sumatriptan and topiramate, respectively. After 5 sessions of NTG injections, the GABAsynthesizing enzyme, 65-kDa glutamate decarboxylase (GAD65), but not the GABA transporter 1 (GAT1) or the α6 subunitcontaining GABA A receptors (α6GABA A Rs), was downregulated in mouse TG tissues. Taking advantage of the unaffected TG α6GABA A R expression in NTG-treated mice, we demonstrated that an α6GABA A R-selective positive allosteric modulator (PAM), DK-I-56-1, exhibited both abortive and prophylactic effects, comparable to those of sumatriptan and topiramate, respectively, in this migraine-mimicking mouse model. The brain-impermeable furosemide significantly prevented the effects of DK-I-56-1, suggesting its peripheral site of action, likely via preventing α6GABA A R modulation in TG. Results suggest that a decreased GABA synthesis caused by the reduced GAD65 expression in TG contributes to the trigeminovascular activation in this repeated NTG-induced migraine-mimicking model and that the unaltered α6GABA A Rs in TG are potential targets for migraine treatment. Thus, α6GABA A R-selective PAMs are potential anti-migraine agents for both abortive and preventive therapies.Key Words Migraine . α6 subunit-containing GABA A receptor . trigeminal ganglia . nitroglycerin . mouse grimacescale . 65-kDa glutamate decarboxylase . GABA transporter 1.Hung-Ruei Tzeng and Ming Tatt Lee contributed equally to this work.

show abstract

“…Irrespectively, the orthosteric binding sites are located at the  (+)  -) interfaces in the extracellular domain (ECD), and a number of allosteric binding sites have also been identified in the subunit interfaces of both the ECD and TMD (Olsen, 2018). These include for example the benzodiazepine site in the ECD  (+)  (-) interface, responsible for mediating the anxiolytic and sleep-inducing effect of the benzodiazepines, including diazepam (Valium  ), widely used in the clinic (Sigel and Steinmann, 2012;Simeone et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Molecular Determinants Underlying Delta Selective Compound 2 Activity at δ-Containing GABA_A Receptors

et al. 2021

View full text Add to dashboard Cite

Delta selective compound 2 (DS2) is one of the most widely used tools to study selective actions mediated by  subunit-containing GABA A receptors. DS2 was discovered over 10 years ago, but despite great efforts, the precise molecular site of action has remained elusive.Using a combination of computational modeling, site-directed mutagenesis and cell-based pharmacological assays, we probed three potential binding sites for DS2 and analogs at  4  1  receptors: an  4 (+)  (-) interface site in the extracellular domain (ECD), equivalent to the This article has not been copyedited and formatted. The final version may differ from this version.

show abstract

Defined concatenated α6α1β3γ2 GABAA receptor constructs reveal dual action of pyrazoloquinolinone allosteric modulators

Cited by 13 publications

References 38 publications

Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum

Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum

α6GABAA Receptor Positive Modulators Alleviate Migraine-like Grimaces in Mice via Compensating GABAergic Deficits in Trigeminal Ganglia

Molecular Determinants Underlying Delta Selective Compound 2 Activity at δ-Containing GABA_A Receptors

Contact Info

Product

Resources

About

Defined concatenated α6α1β3γ2 GABAA receptor constructs reveal dual action of pyrazoloquinolinone allosteric modulators

Cited by 13 publications

References 38 publications

Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum

Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum

α6GABAA Receptor Positive Modulators Alleviate Migraine-like Grimaces in Mice via Compensating GABAergic Deficits in Trigeminal Ganglia

Molecular Determinants Underlying Delta Selective Compound 2 Activity at δ-Containing GABAA Receptors

Contact Info

Product

Resources

About

Molecular Determinants Underlying Delta Selective Compound 2 Activity at δ-Containing GABA_A Receptors