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Positive allosteric modulator

Gaia Pasqualetto, Andrea Brancale, Mark T Young
P2X receptors are trimeric eukaryotic ATP-gated cation channels. Extracellular ATP-their physiological ligand-is released as a neurotransmitter and in conditions of cell damage such as inflammation, and substantial evidence implicates P2X receptors in diseases including neuropathic pain, cancer, and arthritis. In 2009, the first P2X crystal structure, Danio rerio P2X4 in the apo - state, was published, and this was followed in 2012 by the ATP-bound structure. These structures transformed our understanding of the conformational changes induced by ATP binding and the mechanism of ligand specificity, and enabled homology modeling of mammalian P2X receptors for ligand docking and rational design of receptor modulators...
2018: Frontiers in Pharmacology
Emma Rie Olander, Nawid Madjroh, Lennart Bunch, Pella Cecilia Söderhielm, Anders A Jensen
The retigabine analog 2-amino-4-(2,4,6-trimethylbenzylamino)-phenyl]-carbamic acid ethyl ester (AA29504) is a positive allosteric modulator (PAM) of γ-aminobutyric acidA receptors (GABAA Rs), and the modulator has been used in ex vivo/in vivo studies to probe the physiological roles of native δ-containing GABAA Rs. In this study, the functional properties and mode of action of AA29504 were investigated at human GABAA Rs expressed in Xenopus oocytes by two-electrode voltage clamp electrophysiology. AA29504 was found to be an allosteric GABAA R agonist displaying low intrinsic activities at 3-30 μM...
February 15, 2018: Biochemical Pharmacology
Ioana Neagoe, Chang Liu, Alexander Stumpf, Yanmei Lu, Dongping He, Ross Francis, Jun Chen, Paul Reynen, Moulay Hicham Alaoui-Ismaili, Hirokazu Fukui
Abnormal signaling pathways mediated by N-methyl-d-aspartate receptors (NMDARs) have been implicated in the pathogenesis of various CNS disorders and have been long considered as promising points of therapeutic intervention. However, few efforts have been previously described concerning evaluation of therapeutic modulators of NMDARs and their downstream pathways in human neurons with endogenous expression of NMDARs. In the present study, we assessed expression, functionality, and subunit composition of endogenous NMDARs in human induced pluripotent stem cell (hiPSC)-derived cortical neurons (iCell Neurons and iCell GlutaNeurons)...
February 8, 2018: Stem Cell Research
Dorota Zolkowska, Chun-Yi Wu, Michael A Rogawski
Allopregnanolone (5α-pregnan-3α-ol-20-one) and its synthetic 3β-methyl analog, ganaxolone, are positive allosteric modulators of synaptic and extrasynaptic γ-aminobutyric acid (GABA) A receptors that exhibit antiseizure activity in diverse animal seizure models, including models of status epilepticus (SE). The 2 neuroactive steroids are being investigated as treatments for SE, including as a treatment for SE induced by chemical threat agents. Intramuscular injection is the preferred route of administration in the prehospital treatment of SE...
February 17, 2018: Epilepsia
Magdalena Korczynska, Mary J Clark, Celine Valant, Jun Xu, Ee Von Moo, Sabine Albold, Dahlia R Weiss, Hayarpi Torosyan, Weijiao Huang, Andrew C Kruse, Brent R Lyda, Lauren T May, Jo-Anne Baltos, Patrick M Sexton, Brian K Kobilka, Arthur Christopoulos, Brian K Shoichet, Roger K Sunahara
Subtype-selective antagonists for muscarinic acetylcholine receptors (mAChRs) have long been elusive, owing to the highly conserved orthosteric binding site. However, allosteric sites of these receptors are less conserved, motivating the search for allosteric ligands that modulate agonists or antagonists to confer subtype selectivity. Accordingly, a 4.6 million-molecule library was docked against the structure of the prototypical M 2 mAChR, seeking molecules that specifically stabilized antagonist binding. This led us to identify a positive allosteric modulator (PAM) that potentiated the antagonist N -methyl scopolamine (NMS)...
February 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
Dina Manetti, Cristina Bellucci, Niccolò Chiaramonte, Silvia Dei, Elisabetta Teodori, Maria Novella Romanelli
Nicotinic receptors are membrane proteins involved in several physiological processes. They are considered suitable drug targets for various CNS disorders or conditions, as shown by the large number of compounds which have entered clinical trials. In recent years, nonconventional agonists have been discovered: positive allosteric modulators, allosteric agonists, site-specific agonists and silent desensitizers are compounds able to modulate the receptor interacting at sites different from the orthodox one, or to desensitize the receptor without prior opening...
February 16, 2018: Future Medicinal Chemistry
Francesco Di Virgilio, Anna L Giuliani, Valentina Vultaggio-Poma, Simonetta Falzoni, Alba C Sarti
The P2X7 receptor (P2X7R) is a ligand-gated plasma membrane ion channel belonging to the P2X receptor subfamily activated by extracellular nucleotides. General consensus holds that the physiological (and maybe the only) agonist is ATP. However, scattered evidence generated over the last several years suggests that ATP might not be the only agonist, especially at inflammatory sites. Solid data show that NAD + covalently modifies the P2X7R of mouse T lymphocytes, thus lowering the ATP threshold for activation...
2018: Frontiers in Pharmacology
Erica S Burnell, Mark W Irvine, Guangyu Fang, Kiran Sapkota, David E Jane, Daniel T Monaghan
Excitatory activity in the CNS is predominately mediated by L-glutamate through several families of L-glutamate neurotransmitter receptors. Of these, the N-methyl-D-aspartate receptor (NMDAR) family has many critical roles in CNS function and in various neuropathological and psychiatric conditions. Until recently, the types of compounds available to regulate NMDAR function have been quite limited in terms of mechanism of action, subtype selectivity, and biological effect. However, several new classes of NMDAR agents have now been identified that are positive or negative allosteric modulators (PAMs and NAMs, respectively) with various patterns of NMDAR subtype selectivity...
February 15, 2018: Journal of Medicinal Chemistry
Xiao Yu, Nicholas P Franks, William Wisden
Sedatives target just a handful of receptors and ion channels. But we have no satisfying explanation for how activating these receptors produces sedation. In particular, do sedatives act at restricted brain locations and circuitries or more widely? Two prominent sedative drugs in clinical use are zolpidem, a GABA A receptor positive allosteric modulator, and dexmedetomidine (DEX), a selective α2 adrenergic receptor agonist. By targeting hypothalamic neuromodulatory systems both drugs induce a sleep-like state, but in different ways: zolpidem primarily reduces the latency to NREM sleep, and is a controlled substance taken by many people to help them sleep; DEX produces prominent slow wave activity in the electroencephalogram (EEG) resembling stage 2 NREM sleep, but with complications of hypothermia and lowered blood pressure-it is used for long term sedation in hospital intensive care units-under DEX-induced sedation patients are arousable and responsive, and this drug reduces the risk of delirium...
2018: Frontiers in Neural Circuits
Daniel F Legler, Marcus Thelen
Chemokine signaling is essential for coordinated cell migration in health and disease to specifically govern cell positioning in space and time. Typically, chemokines signal through heptahelical, G protein-coupled receptors to orchestrate cell migration. Notably, chemokine receptors are highly dynamic structures and signaling efficiency largely depends on the discrete contact with the ligand. Promiscuity of both chemokines and chemokine receptors, combined with biased signaling and allosteric modulation of receptor activation, guarantees a tightly controlled recruitment and positioning of individual cells within the local environment at a given time...
2018: F1000Research
Sinem Milanos, Katharina Kuenzel, Daniel F Gilbert, Dieter Janzen, Manju Sasi, Andrea Buettner, Thomas M Frimurer, Carmen Villmann
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...
November 27, 2017: Biological Chemistry
Richard W Olsen
gamma-Aminobutyric acid (GABA)-mediated inhibitory neurotransmission and the gene products involved were discovered during the mid-twentieth century. Historically, myriad existing nervous system drugs act as positive and negative allosteric modulators of these proteins, making GABA a major component of modern neuropharmacology, and suggesting that many potential drugs will be found that share these targets. Although some of these drugs act on proteins involved in synthesis, degradation, and membrane transport of GABA, the GABA receptors Type A (GABAAR) and Type B (GABABR) are the targets of the great majority of GABAergic drugs...
January 30, 2018: Neuropharmacology
Klaus Deckmann, Amir Rafiq, Christian Erdmann, Christian Illig, Melanie Durschnabel, Jürgen Wess, Wolfgang Weidner, Thomas Bschleipfer, Wolfgang Kummer
We have recently identified a cholinergic chemosensory cell in the urethral epithelium, urethral brush cell (UBC), that, upon stimulation with bitter or bacterial substances, initiates a reflex detrusor activation. Here, we elucidated cholinergic mechanisms that modulate UBC responsiveness. We analyzed muscarinic acetylcholine receptor (M1-5 mAChR) expression by using RT-PCR in UBCs, recorded [Ca2+]i responses to a bitter stimulus in isolated UBCs of wild-type and mAChR-deficient mice, and performed cystometry in all involved strains...
January 17, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Christian C Felder, Paul J Goldsmith, Kimberley Jackson, Helen E Sanger, David A Evans, Adrian J Mogg, Lisa M Broad
The cholinergic signalling system has been an attractive pathway to seek targets for modulation of arousal, cognition, and attention which are compromised in neurodegenerative and neuropsychiatric diseases. The acetylcholine muscarinic receptor M1 and M4 subtypes which are highly expressed in the central nervous system, in cortex, hippocampus and striatum, key areas of cognitive and neuropsychiatric control, have received particular attention. Historical muscarinic drug development yielded first generation agonists with modest selectivity for these two receptor targets over M2 and M3 receptors, the major peripheral sub-types hypothesised to underlie the dose-limiting clinical side effects...
January 25, 2018: Neuropharmacology
Melanie Abongwa, Djordje S Marjanovic, James G Tipton, Fudan Zheng, Richard J Martin, Sasa M Trailovic, Alan P Robertson
Zolvix® is a recently introduced anthelmintic drench containing monepantel as the active ingredient. Monepantel is a positive allosteric modulator of DEG-3/DES-2 type nicotinic acetylcholine receptors (nAChRs) in several nematode species. The drug has been reported to produce hypercontraction of Caenorhabditis elegans and Haemonchus contortus somatic muscle. We investigated the effects of monepantel on nAChRs from Ascaris suum and Oesophagostomum dentatum heterologously expressed in Xenopus laevis oocytes...
December 16, 2017: International Journal for Parasitology, Drugs and Drug Resistance
Katarzyna M Targowska-Duda, Agnieszka A Kaczor, Krzysztof Jozwiak, Hugo R Arias
The binding site locations and structural components for type I and type II positive allosteric modulators (PAMs) of the α7 nicotinic acetylcholine receptor (nAChR) have not been fully characterized yet. In this regard, homology models of the human α7 nAChR and hα7/m5-HT3A chimera, built using the crystal structure of the serotonin type 3A receptor (5-ΗΤ3ΑR), were used for molecular docking and molecular dynamics simulations to study the molecular interactions of selected type I (5-hydroxyindol, NS-1738, and LY-2087101) and type II (PNU-120596, PAM-2, and TBS-516) PAMs...
January 24, 2018: Journal of Biomolecular Structure & Dynamics
Paul Campitelli, Jingjing Guo, Huan-Xiang Zhou, Sefika Banu Ozkan
Allostery, which is regulation from distant sites, plays a major role in biology. While traditional allostery is described in terms of conformational change upon ligand binding as an underlying principle, it is possible to have allosteric regulations without significant conformational change through modulating the conformational dynamics by altering the local effective elastic modulus of the protein upon ligand binding. Pin1 utilizes this dynamic allostery to regulate its function. It is a modular protein containing a WW domain and a larger peptidyl prolyl isomerase domain (PPIase) that isomerizes phospho-serine/threonine-proline (pS/TP) motifs, The WW domain serves as a docking module, whereas catalysis solely takes place within the PPIase...
January 23, 2018: Journal of Physical Chemistry. B
Cameron S Metcalf, Brian D Klein, Misty D Smith, Marc Ceusters, Hilde Lavreysen, Stefan Pype, Nancy Van Osselaer, Roy Twyman, H Steve White
OBJECTIVE: We previously demonstrated that positive allosteric modulators (PAMs) of metabotropic glutamate subtype 2 (mGlu2 ) receptors have potential synergistic interactions with the antiseizure drug levetiracetam (LEV). The present study utilizes isobolographic analysis to evaluate the combined administration of JNJ-46356479, a selective and potent mGlu2 PAM, with LEV as well as sodium valproate (VPA) and lamotrigine (LTG). METHODS: The anticonvulsant efficacy of JNJ-46356479 was evaluated in the 6-Hz model of psychomotor seizures in mice...
January 23, 2018: Epilepsia
Nicholas A Ferraro, Michael Cascio
The glycine receptor (GlyR) belongs to a superfamily of pentameric ligand-gated ion channels (pLGICs) that mediate fast neurotransmission. GlyR typically modulates inhibitory transmission by antagonizing membrane depolarization through anion influx. Allosteric interactions between the receptor and its lipid surroundings affect receptor function, and cholesterol is essential for pLGIC activity. Cholesterol at compositions below ~33 mol percent has been shown to have negligible chemical activity, suggesting that specific interactions between membrane proteins and cholesterol become significant only at concentrations above this stoichiometric threshold...
January 22, 2018: Analytical Chemistry
Mariam Alaverdashvili, Robert B Laprairie
Allosteric modulation of the type 1 cannabinoid receptor (CB1R) holds great therapeutic potential. This is because allosteric modulators do not possess intrinsic efficacy, but instead augment (positive allosteric modulation) or diminish (negative allosteric modulation) the receptor's response to endogenous ligand. Consequently, CB1R allosteric modulators have an effect ceiling which allows for the tempering of CB1R signaling without the desensitization, tolerance, dependence, and psychoactivity associated with orthosteric compounds...
January 21, 2018: Drug Metabolism Reviews
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