Residues in Transmembrane Domains I and II Determine γ-Aminobutyric Acid Type A<sub>A</sub>Receptor Subtype-Selective Antagonism by Furosemide

Thompson, Sally A.; Arden, S A; Marshall, George R.; Wingrove, Peter B.; Whiting, Paul J.; Wafford, Keith A.

doi:10.1124/mol.55.6.993

Cited by 60 publications

(53 citation statements)

References 13 publications

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“…In fact, the use of Xenopus oocytes to characterize recombinant mammalian GABA A Rs dates back to the 1980s (55,56). Since then, numerous studies have used this expression system to characterize particular GABA A R subunit compositions in functional and pharmacological terms (57)(58)(59)(60). Moreover, biochemical regulation of recombinant GABA A R expression has often been studied in oocytes (61,62), and it has been demonstrated that these receptors, either expressed in human embryonic kidney cells or in Xenopus oocytes, are similarly modulated by PKC (63).…”

Section: Discussionmentioning

confidence: 99%

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway

Serantes

Arnalich

Figueroa

et al. 2006

Journal of Biological Chemistry

118

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Sepsis-associated encephalopathy (SAE) is a frequent but poorly understood neurological complication in sepsis that negatively influences survival. Here we present clinical and experimental evidence that this brain dysfunction may be related to altered neurotransmission produced by inflammatory mediators. Compared with septic patients, SAE patients had higher interleukin-1␤ (IL-1␤) plasma levels; interestingly, these levels decreased once the encephalopathy was resolved. A putative IL-1␤ effect on type A ␥-aminobutyric acid receptors (GABA A Rs), which mediate fast synaptic transmission in most cerebral inhibitory synapses in mammals, was investigated in cultured hippocampal neurons and in Xenopus oocytes expressing native or foreign rat brain GABA A Rs, respectively. Confocal images in both cell types revealed that IL-1␤ increases recruitment of GABA A Rs to the cell surface. Moreover, brief applications of IL-1␤ to voltage-clamped oocytes yielded a delayed potentiation of the GABA-elicited chloride currents (I GABA ); this effect was suppressed by IL-1ra, the natural IL-1 receptor (IL-1RI) antagonist. Western blot analysis combined with I GABA recording and confocal images of GABA A Rs in oocytes showed that IL-1␤ stimulates the IL-1RI-dependent phosphatidylinositol 3-kinase activation and the consequent facilitation of phospho-Akt-mediated insertion of GABA A Rs into the cell surface. The interruption of this signaling pathway by specific phosphatidylinositol 3-kinase or Akt inhibitors suppresses the cytokine-mediated effects on GABA A R, whereas activation of the conditionally active form of Akt1 (myr-Akt1.ER*) with 4-hydroxytamoxifen reproduces the effects. These findings point to a previously unrecognized signaling pathway that connects IL-1␤ with increased "GABAergic tone." We propose that through this mechanism IL-1␤ might alter synaptic strength at central GABAergic synapses and so contribute to the cognitive dysfunction observed in SAE.

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Section: Discussionmentioning

confidence: 99%

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway

Serantes

Arnalich

Figueroa

et al. 2006

Journal of Biological Chemistry

118

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“…A number of allosteric modulators demonstrate b-subunit selectivity, for example, loreclezole, etomidate, furosemide Hill-Venning et al, 1997;Thompson et al, 1999). Regardless of whether the compound inhibits (e.g.…”

Section: Interaction With Other Gaba a Receptor Ligandsmentioning

confidence: 99%

“…In recent years, a number of modulators of the GABA A receptor have been reported that demonstrate b2/3 selectivity over b1, for example, loreclezole, etomidate, tracazolate, mefenamic acid, furosemide Hill-Venning et al, 1997;Halliwell et al, 1999;Thompson et al, 1999;. In all cases, the potency of the modulator was reduced or abolished when serine was introduced into b2 or b3 (position 289 in human b2 and 290 in human b3) and increased or conferred when asparagine was introduced into b1 (position 290).…”

Section: Comparison With Other B-selective Compoundsmentioning

confidence: 99%

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Thompson

Wheat

Brown

et al. 2004

British J Pharmacology

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1 A high-throughput assay utilizing the voltage/ion probe reader (VIPR) technology identified salicylidene salicylhydrazide (SCS) as being a potent selective inhibitor of a2b1g1y GABA A receptors with a maximum inhibition of 5675% and an IC 50 of 32 (23, 45) nM. 2 Evaluation of this compound using patch-clamp electrophysiological techniques demonstrated that the compound behaved in a manner selective for receptors containing the b1 subunit (e.g. maximum inhibition of 68.172.7% and IC 50 value of 5.3 (4.4, 6.5) nM on a2b1g1 receptors). The presence of a b1 subunit was paramount for the inhibition with changes between a1 and a2, g1 and g2, and the presence of a y subunit having little effect. 3 On all subtypes, SCS produced incomplete inhibition with the greatest level of inhibition at a1b1g1y receptors (74.371.4%). SCS displayed no use or voltage dependence, suggesting that it does not bind within the channel region. Concentration -response curves to GABA in the presence of SCS revealed a reduction in the maximum response with no change in the EC 50 or Hill coefficient. In addition, SCS inhibited pentobarbitone-induced currents. 4 Threonine 255, located within transmembrane domain (TM) 1, and isoleucine 308, located extracellularly just prior to TM3, were required for inhibition by SCS. 5 SCS did not compete with the known allosteric modulators, picrotoxin, pregnenolone sulphate, dehydroepiandrosterone 3-sulphate, bicuculline, loreclezole or mefenamic acid. Neither was the inhibition by SCS influenced by the benzodiazepine site antagonist flumazenil. 6 In conclusion, SCS is unique in selectively inhibiting GABA A receptors containing the b1 subunit via an allosteric mechanism. The importance of threonine 255 and isoleucine 308 within the b1 subunit and the lack of interaction with a range of GABA A receptor modulators suggests that SCS is interacting at a previously unidentified site.

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“…It has previously been suggested that these processes are coupled together functionally and structurally (Boileau and Czajkowski, 1999;Thompson et al, 1999;Carlson et al, 2000;Kash et al, 2003;Miyazawa et al, 2003). In the nicotinic AChR (nAChR), as in all other members of the cys-loop superfamily of LGICs, the ligand-binding domain is located between two subunit interfaces (␣/␥ and ␣/␦ for nAChRs) in the extracellular N termini, and gating occurs in the pore-lining M2 segment.…”

Section: Discussionmentioning

confidence: 99%

Structural Determinants of Benzodiazepine Allosteric Regulation of GABA_AReceptor Currents

Jones-Davis¹,

Song²,

Gallagher³

et al. 2005

J. Neurosci.

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Benzodiazepine enhancement of GABA A receptor current requires a ␥ subunit, and replacement of the ␥ subunit by the ␦ subunit abolishes benzodiazepine enhancement. Although it has been demonstrated that benzodiazepines bind to GABA A receptors at the junction between ␣ and ␥ subunits, the structural basis for the coupling of benzodiazepine binding to allosteric enhancement of the GABA A receptor current is unclear. To determine the structural basis for this coupling, the present study used a chimera strategy, using ␥2L-␦ GABA A receptor subunit chimeras coexpressed with ␣1 and ␤3 subunits in human embryonic kidney 293T cells. Different domains of the ␥2L subunit were replaced by ␦ subunit sequence, and diazepam sensitivity was determined. Chimeric subunits revealed two areas of interest: domain 1 in transmembrane domain 1 (M1) and domain 2 in the C-terminal portion of transmembrane domain 2 (M2) and the M2-M3 extracellular loop. In those domains, site-directed mutagenesis demonstrated that the following two groups of residues were involved in benzodiazepine transduction of current enhancement: residues Y235, F236, T237 in M1; and S280, T281, I282 in M2 as well as the entire M2-M3 loop. These results suggest that a pocket of residues may transduce benzodiazepine binding to increased gating. Benzodiazepine transduction involves a group of residues that connects the N terminus and M1, and another group of residues that may facilitate an interaction between the N terminus and the M2 and M2-M3 loop domains.

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Residues in Transmembrane Domains I and II Determine γ-Aminobutyric Acid Type A_AReceptor Subtype-Selective Antagonism by Furosemide

Cited by 60 publications

References 13 publications

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Structural Determinants of Benzodiazepine Allosteric Regulation of GABA_AReceptor Currents

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Residues in Transmembrane Domains I and II Determine γ-Aminobutyric Acid Type AAReceptor Subtype-Selective Antagonism by Furosemide

Cited by 60 publications

References 13 publications

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABAAreceptors

Structural Determinants of Benzodiazepine Allosteric Regulation of GABAAReceptor Currents

Contact Info

Product

Resources

About

Residues in Transmembrane Domains I and II Determine γ-Aminobutyric Acid Type A_AReceptor Subtype-Selective Antagonism by Furosemide

Salicylidene salicylhydrazide, a selective inhibitor ofβ1‐containing GABA_Areceptors

Structural Determinants of Benzodiazepine Allosteric Regulation of GABA_AReceptor Currents