scholarly journals Cryo-EM structure of the benzodiazepine-sensitive α1β1γ2S tri-heteromeric GABAA receptor in complex with GABA

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Swastik Phulera ◽  
Hongtao Zhu ◽  
Jie Yu ◽  
Derek P Claxton ◽  
Nate Yoder ◽  
...  
Keyword(s):  
Ion Channel ◽  
Gabaa Receptor ◽  
Gabaa Receptors ◽  
Rational Design ◽  
Neurological Diseases ◽  
Therapeutic Agents ◽  
Structural Studies ◽  
Mutant Forms ◽  
Receptor Assembly ◽  
Α1 Subunit

Fast inhibitory neurotransmission in the mammalian nervous system is largely mediated by GABAA receptors, chloride-selective members of the superfamily of pentameric Cys-loop receptors. Native GABAA receptors are heteromeric assemblies sensitive to many important drugs, from sedatives to anesthetics and anticonvulsant agents, with mutant forms of GABAA receptors implicated in multiple neurological diseases. Despite the profound importance of heteromeric GABAA receptors in neuroscience and medicine, they have proven recalcitrant to structure determination. Here we present the structure of a tri-heteromeric α1β1γ2SEM GABAA receptor in complex with GABA, determined by single particle cryo-EM at 3.1–3.8 Å resolution, elucidating molecular principles of receptor assembly and agonist binding. Remarkable N-linked glycosylation on the α1 subunit occludes the extracellular vestibule of the ion channel and is poised to modulate receptor assembly and perhaps ion channel gating. Our work provides a pathway to structural studies of heteromeric GABAA receptors and a framework for rational design of novel therapeutic agents.

scholarly journals Cryo-EM structure of the benzodiazepine-sensitive α1β1γ2 heterotrimeric GABAA receptor in complex with GABA illuminates mechanism of receptor assembly and agonist binding

2018 ◽  
Author(s):  
Swastik Phulera ◽  
Hongtao Zhu ◽  
Jie Yu ◽  
Derek P. Claxton ◽  
Nate Yoder ◽  
...  
Keyword(s):  
Ion Channel ◽  
Rational Design ◽  
Neurological Diseases ◽  
Therapeutic Agents ◽  
Structural Studies ◽  
Agonist Binding ◽  
Mutant Forms ◽  
Receptor Assembly ◽  
Anticonvulsive Agents ◽  
Α1 Subunit

ABSTRACTFast inhibitory neurotransmission in the mammalian nervous system is largely mediated by GABAA receptors, chloride-selective members of the superfamily of pentameric Cys-loop receptors. Native GABAA receptors are heteromeric assemblies sensitive to many important drugs, from sedatives to anesthetics and anticonvulsive agents, with mutant forms of GABAA receptors implicated in multiple neurological diseases, including epilepsy. Despite the profound importance of heteromeric GABAA receptors in neuroscience and medicine, they have proven recalcitrant to structure determination. Here we present the structure of the triheteromeric α1β1γ2EM GABAA receptor in complex with GABA, determined by single particle cryo-EM at 3.1-3.8 Å resolution, elucidating the molecular principles of receptor assembly and agonist binding. Remarkable N-linked glycosylation on the α1 subunit occludes the extracellular vestibule of the ion channel and is poised to modulate receptor assembly and perhaps ion channel gating. Our work provides a pathway to structural studies of heteromeric GABAA receptors and a framework for the rational design of novel therapeutic agents.

Multiple assembly signals in γ-aminobutyric acid (type A) receptor subunits combine to drive receptor construction and composition

2003 ◽  
Vol 31 (4) ◽  
pp. 875-879 ◽  
Author(s):  
K. Bollan ◽  
L.A. Robertson ◽  
H. Tang ◽  
C.N. Connolly
Keyword(s):  
Gabaa Receptor ◽  
Gabaa Receptors ◽  
Type A ◽  
Aminobutyric Acid ◽  
Single Amino Acid ◽  
Functional Surface ◽  
Surface Receptors ◽  
Acid Type ◽  
Absolute Requirement ◽  
Receptor Assembly

Mammalian γ-aminobutyric acid type A (GABAA) receptors are constructed from a large repertoire of subunits (α1–α6, β1–β3, γ1–γ3, δ, ∊, θ and π) into a pentameric ion channel. GABAA receptor assembly occurs within the endoplasmic reticulum (ER) and involves interactions with chaperone molecules. Only specific subunit combinations can produce functional surface receptors (with a fixed stoichiometry); other subunit combinations are retained within the ER and degraded. Thus, receptor assembly occurs by defined pathways to limit the diversity of GABAA receptors. The key to understanding how receptor diversity is achieved and controlled is the identification of assembly signals capable of distinguishing between other subunit partners. Analysis of an assembly box in α1 (residues 57–68) has revealed an absolute requirement for this region in the assembly of αβ receptors. Furthermore, a selective requirement for a single amino acid (R66) is observed for the assembly of α1β2, but not α1β1 or α1β3, receptors. In addition, we have characterized an assembly signal in the β3 subunit that is capable of driving the assembly of β3, γ2β3 and α1β3 receptors. Interestingly, this signal does not appear to utilize the α1 assembly box, suggesting the presence of alternative assembly signals within the α1 subunit. Although this β3 signal is sufficient to permit the formation of βγ receptors it is not necessary, suggesting that alternative assembly signals also exist within the β3 subunit. These findings support the belief that GABAA receptor assembly occurs via multiple defined pathways that may be determined by subunit availability.

scholarly journals Symptomatic and Disease-Modifying Effects of GABAA Receptor Positive Allosteric Modulation in a Mouse Model of Chronic Stress

2021 ◽  
Author(s):  
Ashley Bernardo ◽  
Philippe Lee ◽  
Michael Marcotte ◽  
Yeunus Mian ◽  
Zubair A. Khan ◽  
...  
Keyword(s):  
Side Effects ◽  
Gabaa Receptor ◽  
Chronic Stress ◽  
Gabaa Receptors ◽  
Brain Regions ◽  
Allosteric Modulation ◽  
Neuronal Morphology ◽  
Racemic Mixture ◽  
Spine Density ◽  
Α1 Subunit

AbstractChronic stress is a major risk factor for developing depressive disorders and animal models of stress recapitulate behavioral, cellular and molecular changes that are observed in human depression. Individuals exposed to chronic stress, or patients with MDD experience mood and cognitive dysfunctions. This is in part due to neuronal shrinkage in brain regions involved in several cognitive functions such as the prefrontal cortex (PFC) and the hippocampus (HPC). Also in the context of depression and chronic stress, expression levels and function of the main inhibitory neurotransmitter GABA are reduced. Thus far, drugs targeting this GABA deficit have failed to produce beneficial effects due to broad activity at various GABA receptor subunits, including the α1-subunit, resulting in broad side effects. However, refined and selective activity at the α2/3/5-subunit is hypothesized to exert beneficial effect, devoid of side effects.Here, we show that GL-II-73 and GL-I-54 exert positive allosteric modulation at the α5, and α2/3/5-contianing GABAA receptors respectively, and that they are effective both independently and in combination. Using unpredictable chronic mild stress (UCMS) experiments in male and female C57BL/6 mice (n=12 per group), we showed that acute and chronic administration of a GL-II-73/GL-I-54 racemic mixture (termed “GL-RM”) reduced anxiety-like phenotypes and reversed a working memory deficit in UCMS exposed mice. Brains from animals receiving chronic treatment were collected and stained using a Golgi staining technique. Using stereological approaches, neuronal morphology was reconstructed and dendritic length, spine count and spine density were assessed in pyramidal neurons of the PFC and hippocampus. Chronic GL-RM rescued spine density depletions caused by UCMS at apical and basal dendrites (PFC and CA1). Interestingly, spine densities in both brain regions were correlated to cognitive performance, confirming ameliorative benefits of GL-RM.Together, results support the value of selectively targeting GABAA receptors, excluding the α1-subunit, to overcome chronic stress-induced mood symptoms and cognitive deficits, as well as detriments in neuronal morphology. This study confirm results that were observed in old mice, using a α5-selective positive allosteric modulator, and reinforce the concept that the α2/3/5-containing GABAA receptor are suitable targets for the treatment of stress-induced disorders.

scholarly journals Monoclonal Antibodies as Neurological Therapeutics

2021 ◽  
Vol 14 (2) ◽  
pp. 92
Author(s):  
Panagiotis Gklinos ◽  
Miranta Papadopoulou ◽  
Vid Stanulovic ◽  
Dimos D. Mitsikostas ◽  
Dimitrios Papadopoulos
Keyword(s):  
Monoclonal Antibodies ◽  
Molecular Mechanisms ◽  
Neurological Diseases ◽  
Therapeutic Agents ◽  
Medical Specialties ◽  
Specific Effects ◽  
Different Types ◽  
Neurological Conditions ◽  
Disease Pathways

Over the last 30 years the role of monoclonal antibodies in therapeutics has increased enormously, revolutionizing treatment in most medical specialties, including neurology. Monoclonal antibodies are key therapeutic agents for several neurological conditions with diverse pathophysiological mechanisms, including multiple sclerosis, migraines and neuromuscular disease. In addition, a great number of monoclonal antibodies against several targets are being investigated for many more neurological diseases, which reflects our advances in understanding the pathogenesis of these diseases. Untangling the molecular mechanisms of disease allows monoclonal antibodies to block disease pathways accurately and efficiently with exceptional target specificity, minimizing non-specific effects. On the other hand, accumulating experience shows that monoclonal antibodies may carry class-specific and target-associated risks. This article provides an overview of different types of monoclonal antibodies and their characteristics and reviews monoclonal antibodies currently in use or under development for neurological disease.

scholarly journals A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

2016 ◽  
Vol 12 ◽  
pp. 125-138 ◽  
Author(s):  
Steven C Zimmerman
Keyword(s):  
Small Molecules ◽  
Supramolecular Chemistry ◽  
Myotonic Dystrophy ◽  
Small Molecule ◽  
Early Life ◽  
Rational Design ◽  
Early Experience ◽  
Therapeutic Agents ◽  
Early Career ◽  
Molecular Tweezers

This review summarizes part of the author’s research in the area of supramolecular chemistry, beginning with his early life influences and early career efforts in molecular recognition, especially molecular tweezers. Although designed to complex DNA, these hosts proved more applicable to the field of host–guest chemistry. This early experience and interest in intercalation ultimately led to the current efforts to develop small molecule therapeutic agents for myotonic dystrophy using a rational design approach that heavily relies on principles of supramolecular chemistry. How this work was influenced by that of others in the field and the evolution of each area of research is highlighted with selected examples.

GABAA Receptor β3 Subunit Deletion Decreases α2/3 Subunits and IPSC Duration

2003 ◽  
Vol 89 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Epolia Ramadan ◽  
Zhanyan Fu ◽  
Gabriele Losi ◽  
Gregg E. Homanics ◽  
Joseph H. Neale ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Cortical Neurons ◽  
Behavioral Deficits ◽  
Inhibitory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Surface Staining ◽  
Α1 Subunit

Deletion of the β3 subunit of the GABAA receptor produces severe behavioral deficits and epilepsy. GABAA receptor-mediated miniature inhibitory postsynaptic currents (mIPSCs) in cortical neurons in cultures from β3 −/− mice were significantly faster than those in β3 +/+ mice and were more prolonged by zolpidem. Surface staining revealed that the number of β2/3, α2, and α3 (but not of α1) subunit-expressing neurons and the intensity of subunit clusters were significantly reduced in β3 −/− mice. Transfection of β3 −/− neurons with β3 cDNA restored β2/3, α2, and α3 subunits immunostaining and slowed mIPSCs decay. We show that the deletion of the β3 subunit causes the loss of a subset of GABAA receptors with α2 and α3 subunits while leaving a receptor population containing predominantly α1 subunit with fast spontaneous IPSC decay and increased zolpidem sensitivity.

In vitro and in vivo GABAA Receptor Interaction of the Propanidid Metabolite 4-(2-[Diethylamino]-2-Oxoethoxy)-3-Methoxy-Benzeneacetic Acid

Pharmacology ◽  
2018 ◽  
Vol 103 (1-2) ◽  
pp. 10-16 ◽  
Author(s):  
Alessia Cenani ◽  
Robert J. Brosnan ◽  
Heather K. Knych
Keyword(s):  
Gabaa Receptor ◽  
Gabaa Receptors ◽  
Water Solubility ◽  
Plasma Concentrations ◽  
Receptor Activation ◽  
Receptor Interaction ◽  
Dependent Manner ◽  
Benzeneacetic Acid

Background: Propanidid is a γ-aminobutyric acid type A (GABAA) receptor agonist general anesthetic and its primary metabolite is 4-(2-[diethylamino]-2-oxoethoxy)-3-methoxy-benzeneacetic acid (DOMBA). Despite having a high water solubility at physiologic pH that might predict low-affinity GABAA receptor interactions, DOMBA is reported to have no effect on GABAA receptor currents, possibly because the DOMBA concentrations studied were simply insufficient to modulate GABAA receptors. Our objectives were to measure the propanidid and DOMBA concentration responses on ­GABAA receptors and to measure the behavioral responses of DOMBA in mice at concentrations that affect GABAA receptor currents in vitro. Methods: GABAA receptors were expressed in oocytes using clones for the human GABAA α1, β2 and γ2s subunits. The effects of DOMBA (0.2–10 mmol/L) and propanidid (0.001–1 mmol/L) on oocyte GABAA currents were studied using standard 2-electrode voltage clamp techniques. Based on in vitro results, 6 mice received ­DOMBA 32 mg intraperitoneal and were observed for occurrence of neurologic effects and DOMBA plasma concentration was measured by liquid chromatography tandem mass spectrometry. Results: DOMBA both directly activates GABAA receptors and antagonizes its GABA-mediated opening in a concentration-dependent manner at concentrations between 5–10 and 0.5–10 mmol/L respectively. In vivo, DOMBA produced rapid onset sedation at plasma concentrations that correlate with direct GABAA receptor activation. Conclusion: DOMBA modulation of GABAA receptors is associated with sedation in mice. Metabolites of propanidid analogues currently in development may similarly modulate GABAA, and impaired elimination of these metabolites could produce clinically relevant neurophysiologic effects.

scholarly journals Tonic Extrasynaptic GABAA Receptor Currents Control Gonadotropin-Releasing Hormone Neuron Excitability in the Mouse

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1551-1561 ◽  
Author(s):  
Janardhan P. Bhattarai ◽  
Seon Ah Park ◽  
Jin Bong Park ◽  
So Yeong Lee ◽  
Allan E. Herbison ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Gabaa Receptors ◽  
Brain Slice ◽  
Resting Membrane Potential ◽  
Receptor Signaling ◽  
Gaba Transporter ◽  
Gnrh Neurons ◽  
Inward Currents ◽  
Synaptic Receptors ◽  
Tonic Current

Abstract It is well established that the GABAA receptor plays an important role in regulating the electrical excitability of GnRH neurons. Two different modes of GABAA receptor signaling exist: one mediated by synaptic receptors generating fast (phasic) postsynaptic currents and the other mediated by extrasynaptic receptors generating a persistent (tonic) current. Using GABAA receptor antagonists picrotoxin, bicuculline methiodide, and gabazine, which differentiate between phasic and tonic signaling, we found that ∼50% of GnRH neurons exhibit an approximately 15-pA tonic GABAA receptor current in the acute brain slice preparation. The blockade of either neuronal (NO711) or glial (SNAP-5114) GABA transporter activity within the brain slice revealed the presence of tonic GABA signaling in ∼90% of GnRH neurons. The GABAA receptor δ subunit is only found in extrasynaptic GABAA receptors. Using single-cell RT-PCR, GABAA receptor δ subunit mRNA was identified in GnRH neurons and the δ subunit–specific agonist 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol was found to activate inward currents in GnRH neurons. Perforated-patch clamp studies showed that 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol exerted the same depolarizing or hyperpolarizing effects as GABA on juvenile and adult GnRH neurons and that tonic GABAA receptor signaling regulates resting membrane potential. Together, these studies reveal the presence of a tonic GABAA receptor current in GnRH neurons that controls their excitability. The level of tonic current is dependent, in part, on neuronal and glial GABA transporter activity and mediated by extrasynaptic δ subunit–containing GABAA receptors.

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