Inter- and Intra-Subunit Butanol/Isoflurane Sites of Action in the Human Glycine Receptor

McCracken, Mandy L.; Gorini, Giorgio; McCracken, Lindsay M.; Mayfield, R. Dayne; Trudell, James R.

doi:10.3389/fnmol.2016.00045

Cited by 7 publications

(10 citation statements)

References 63 publications

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“…Electrophysiological and structural data suggest that the modulation of pLGICs by volatile anesthetics are associated with a binding pocket located in the TMD region. , However, the influence of the ICD in the effects of low isoflurane concentrations is still unknown. To address the possible contribution of the ICD to the volatile anesthetic sensitivity, we tested the sensitivity of both Lily and Lily-ICD to 0.5 mM isoflurane, which is a concentration close to the MAC for isoflurane anesthesia in mammals , (Figure A,B).…”

Section: Resultsmentioning

confidence: 99%

Large Intracellular Domain-Dependent Effects of Positive Allosteric Modulators on Glycine Receptors

Lara

Burgos

Silva-Grecchi

et al. 2019

ACS Chem. Neurosci.

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Glycine receptors (GlyRs) are members of the pentameric ligandgated ionic channel family (pLGICs) and mediate fast inhibitory neurotransmission in the brain stem and spinal cord. The function of GlyRs can be modulated by positive allosteric modulators (PAMs). So far, it is largely accepted that both the extracellular (ECD) and transmembrane (TMD) domains constitute the primary target for many of these PAMs. On the other hand, the contribution of the intracellular domain (ICD) to the PAM effects on GlyRs remains poorly understood.To gain insight about the role of the ICD in the pharmacology of GlyRs, we examined the contribution of each domain using a chimeric receptor. Two chimeras were generated, one consisting of the ECD of the prokaryotic homologue Gloeobacter violaceus ligand-gated ion channel (GLIC) fused to the TMD of the human α 1 GlyR lacking the ICD (Lily) and a second with the ICD (Lily-ICD). The sensitivity to PAMs of both chimeric receptors was studied using electrophysiological techniques. The Lily receptor showed a significant decrease in the sensitivity to four recognized PAMs. Remarkably, the incorporation of the ICD into the Lily background was sufficient to restore the wild-type α 1 GlyR sensitivity to these PAMs. Based on these data, we can suggest that the ICD is necessary to form a pLGIC having full sensitivity to positive allosteric modulators.

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Section: Resultsmentioning

confidence: 99%

Large Intracellular Domain-Dependent Effects of Positive Allosteric Modulators on Glycine Receptors

Lara

Burgos

Silva-Grecchi

et al. 2019

ACS Chem. Neurosci.

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“…Two homology models of the GABA A R were generated using the Modeler module of Discovery Studio 2016 (Biovia, San Diego, CA) as described previously (34). The first model was of the GABA A R in the benzodiazepine-unbound state.…”

Section: Structural Modelingmentioning

confidence: 99%

“…Both of the resulting homology models were assigned the CHARMm force field in Discovery Studio 2016, minimized, and then subjected to molecular dynamics simulations at 300 K as described previously (34). These two models were analyzed for possible electrostatic interactions using Discovery Studio 2016.…”

Section: Structural Modelingmentioning

confidence: 99%

An intersubunit electrostatic interaction in the GABAA receptor facilitates its responses to benzodiazepines

Pflanz

Daszkowski

Cornelison

et al. 2018

Journal of Biological Chemistry

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Benzodiazepines are positive allosteric modulators of the GABA receptor (GABAR), acting at the α-γ subunit interface to enhance GABAR function. GABA or benzodiazepine binding induces distinct conformational changes in the GABAR. The molecular rearrangements in the GABAR following benzodiazepine binding remain to be fully elucidated. Using two molecular models of the GABAR, we identified electrostatic interactions between specific amino acids at the α-γ subunit interface that were broken by, or formed after, benzodiazepine binding. Using two-electrode voltage clamp electrophysiology in oocytes, we investigated these interactions by substituting one or both amino acids of each potential pair. We found that Lys in the α subunit forms an electrostatic bond with Asp of the γ subunit after benzodiazepine binding and that this bond stabilizes the positively modified state of the receptor. Substitution of these two residues to cysteine and subsequent covalent linkage between them increased the receptor's sensitivity to low GABA concentrations and decreased its response to benzodiazepines, producing a GABAR that resembles a benzodiazepine-bound WT GABAR. Breaking this bond restored sensitivity to GABA to WT levels and increased the receptor's response to benzodiazepines. The α Lys and γ Asp interaction did not play a role in ethanol or neurosteroid modulation of GABAR, suggesting that different modulators induce different conformational changes in the receptor. These findings may help explain the additive or synergistic effects of modulators acting at the GABAR.

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“…Isoflurane is a volatile general anesthetic that is used to abolish behavioral responsiveness in animals, in order to attenuate pain and facilitate surgery ( 30 , 31 ). The mechanism underlying isoflurane anesthesia may be associated with the action of the human glycine receptor ( 32 ). In recent years, additional functions of isoflurane have been reported in various types of disease ( 33 – 35 ).…”

Section: Discussionmentioning

confidence: 99%

Isoflurane reduces pain and inhibits apoptosis of myocardial cells through the phosphoinositide 3-kinase/protein kinaseï¿½B signaling pathway in mice during cardiac surgery

Lin

Yang

2018

Mol Med Report

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Heart bypass surgery is the most common treatment for myocardial ischemia. Clinical investigations have revealed that isoflurane anesthesia is efficient to alleviate pain during cardiac surgery, including heart bypass surgery. Previous studies have revealed the protective effects of isoflurane on myocardial cells of patients with myocardial ischemia during the perioperative period. The present study aimed to investigate the mechanism underlying the protective effects of isoflurane on myocardial cells in mice with myocardial ischemia. ELISA, flow cytometry, immunofluorescence and western blotting were used to analyze the effects of isoflurane anesthesia on myocardial cells. Briefly, myocardial cell apoptosis and viability, pain, phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) signaling pathway expression and the pharmacodynamics of isoflurane were studied in mice treated with isoflurane for heart bypass surgery. The results demonstrated that isoflurane anesthesia efficiently attenuated pain in mice during surgery. Viability and apoptosis of myocardial cells was also improved by isoflurane in vitro and in vivo. The PI3K/AKT pathway was upregulated in myocardial cells on day 3 post-operation. Mechanistically, isoflurane promoted PI3K/AKT activation, upregulated B-cell lymphoma 2 (Bcl-2)-associated X protein and Bcl-2 expression levels, and reduced the expression levels of caspase-3 and caspase-8 in myocardial cells. In conclusion, the findings indicated that isoflurane is beneficial for pain attenuation and inhibits apoptosis of myocardial cells via the PI3K/AKT signaling pathway in mice during cardiac surgery.

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Inter- and Intra-Subunit Butanol/Isoflurane Sites of Action in the Human Glycine Receptor

Cited by 7 publications

References 63 publications

Large Intracellular Domain-Dependent Effects of Positive Allosteric Modulators on Glycine Receptors

Large Intracellular Domain-Dependent Effects of Positive Allosteric Modulators on Glycine Receptors

An intersubunit electrostatic interaction in the GABAA receptor facilitates its responses to benzodiazepines

Isoflurane reduces pain and inhibits apoptosis of myocardial cells through the phosphoinositide 3-kinase/protein kinaseï¿½B signaling pathway in mice during cardiac surgery

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