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Rohbeck E, Hasse B, Koopmans G, Romero A, Belgardt BF, Roden M, Eckel J, Romacho T. Positive allosteric γ-aminobutyric acid type A receptor modulation prevents lipotoxicity-induced injury in hepatocytes in vitro. Diabetes Obes Metab 2022; 24:1498-1508. [PMID: 35434888 DOI: 10.1111/dom.14719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/29/2022]
Abstract
AIM To determine if a novel positive allosteric modulator of the γ-aminobutyric acid type A (GABAA ) receptor, the thioacrylamide-derivative HK4, which does not penetrate the blood-brain barrier, protects human hepatocytes against lipotoxicity-induced injury. MATERIALS AND METHODS Allosteric modulation of the GABAA receptor by HK4 was determined by patch clamp in HEK-293 cells, calcium influx in INS-1E cells and by using the specific GABAA channel blockers picrotoxin and tert-butylbicyclophosphorothionate (TBPS) in HepG2 cells. Apoptosis was analysed using caspase 3/7, terminal deoxynucleotidyl transferase-dUTP nick end labelling (TUNEL) and array assays in HepG2 cells and/or human primary hepatocytes. Phosphorylation of STAT3 and the NF-κB subunit p65, protein disulphide isomerase (PDI) and poly-ADP-ribose polymerase-1 (PARP-1) was detected by Western blotting. RESULTS Patch clamping, calcium influx measurements and apoptosis assays with the non-competitive GABAA channel blockers picrotoxin and TBPS proved HK4 as a selective positive allosteric modulator of the GABAA receptor. In HepG2 cells, which expressed the main GABAA receptor subunits, HK4 prevented palmitate-induced apoptosis. This protective effect was mediated by downregulation of caspase 3/7 activity and was additionally verified by TUNEL assay. HK4 effectively prevented palmitate-induced apoptosis in human primary hepatocytes. HK4 reduced STAT3 and NF-κB phosphorylation, reduced cleaved PARP-1 expression and upregulated the endoplasmic reticulum (ER) chaperone PDI. CONCLUSIONS HK4 reduced lipotoxic-induced apoptosis by preventing inflammation, DNA damage and ER stress. We propose that the effect of HK4 is mediated by STAT3 and NF-κB. It is suggested that thioacrylamide compounds represent an innovative pharmacological tool to treat or prevent non-alcoholic steatohepatitis as first-in-class drugs.
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Affiliation(s)
- Elisabeth Rohbeck
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | | | | | - Alejandra Romero
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Bengt-Frederik Belgardt
- Institute for Vascular and Islet Cell Biology, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Partner Düsseldorf, München-Neuherberg, Germany
| | - Michael Roden
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Partner Düsseldorf, München-Neuherberg, Germany
- Department of Endocrinology and Diabetology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Jürgen Eckel
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Tania Romacho
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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Nieman AN, Li G, Zahn NM, Mian MY, Mikulsky BN, Hoffman DA, Wilcox TM, Kehoe AS, Luecke IW, Poe MM, Alvarez-Carbonell D, Cook JM, Stafford DC, Arnold LA. Targeting Nitric Oxide Production in Microglia with Novel Imidazodiazepines for Nonsedative Pain Treatment. ACS Chem Neurosci 2020; 11:2019-2030. [PMID: 32511908 PMCID: PMC7380323 DOI: 10.1021/acschemneuro.0c00324] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The goal of this research is the identification of new treatments for neuropathic pain. We characterized the GABAergic system of immortalized mouse and human microglia using electrophysiology and qRT-PCR. Cells from both species exhibited membrane current changes in response to γ-aminobutyric acid, with an EC50 of 260 and 1940 nM, respectively. Human microglia expressed high levels of the γ-aminobutyric acid type A receptor (GABAAR) α3 subunit, which can assemble with β1 and γ2/δ subunits to form functional GABAARs. Mouse microglia contained α2, α3, and α5, in addition to β1-3, γ1-2, and δ, mRNA, enabling a more diverse array of GABAARs than human microglia. Benzodiazepines are well-established modulators of GABAAR activity, prompting a screen of a library of diverse benzodiazepines in microglia for cellular effects. Several active compounds were identified by reduction of nitric oxide (NO) in interferon gamma and lipopolysaccharide activated microglia. However, further investigation with GABAAR antagonists flumazenil, picrotoxin, and bicuculline demonstrated that GABAARs were not linked to the NO response. A screen of 48 receptors identified the κ-opioid receptor and to a lesser extent the μ-opioid receptor as molecular targets, with opioid receptor antagonist norbinaltorphimine reversing benzodiazepine induced reduction of microglial NO. Functional assays identified the downregulation of inducible NO synthase as the mode of action of imidazodiazepines MP-IV-010 and GL-IV-03. Like other κ-opioid receptor agonists, GL-IV-03 reduced the agitation response in both phases of the formalin nociception test. However, unlike other κ-opioid receptor agonists, MP-IV-010 and GL-IV-03 did not impair sensorimotor coordination in mice. Thus, MP-IV-010 and GL-IV-03 represent a new class of nonsedative drug candidates for inflammatory pain.
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Affiliation(s)
- Amanda N. Nieman
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Guanguan Li
- Shenzhen Grubbs Institute and Department of Chemistry, Shenzhen Key Laboratory of Small Molecule Drug Discovery and Synthesis, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Nicolas M. Zahn
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Md Yeunus Mian
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | | | - Dylan A. Hoffman
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Taylor M. Wilcox
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Alexander S. Kehoe
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Ian W. Luecke
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Michael M. Poe
- Department of Chemistry, Western Michigan University, Kalamazoo MI 49008, United States
| | - David Alvarez-Carbonell
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - James M. Cook
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Douglas C. Stafford
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
- Pantherics Incorporated, La Jolla, California 92037, United States
| | - Leggy A. Arnold
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
- Pantherics Incorporated, La Jolla, California 92037, United States
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Yuan NY, Poe MM, Witzigmann C, Cook JM, Stafford D, Arnold LA. Characterization of GABA A receptor ligands with automated patch-clamp using human neurons derived from pluripotent stem cells. J Pharmacol Toxicol Methods 2016; 82:109-114. [PMID: 27544543 DOI: 10.1016/j.vascn.2016.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 05/31/2016] [Accepted: 08/14/2016] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Automated patch clamp is a recent but widely used technology to assess pre-clinical drug safety. With the availability of human neurons derived from pluripotent stem cells, this technology can be extended to determine CNS effects of drug candidates, especially those acting on the GABAA receptor. METHODS iCell Neurons (Cellular Dynamics International, A Fujifilm Company) were cultured for ten days and analyzed by patch clamp in the presence of agonist GABA or in combination with positive allosteric GABAA receptor modulators. Both efficacy and affinity were determined. In addition, mRNA of GABAA receptor subunits were quantified by qRT-PCR. RESULTS We have shown that iCell Neurons are compatible with the IonFlux microfluidic system of the automated patch clamp instrument. Resistance ranging from 15 to 25MΩ was achieved for each trap channel of patch clamped cells in a 96-well plate format. GABA induced a robust change of current with an EC50 of 0.43μM. Positive GABAA receptor modulators diazepam, HZ-166, and CW-04-020 exhibited EC50 values of 0.42μM, 1.56μM, and 0.23μM, respectively. The α2/α3/α5 selective compound HZ-166-induced the highest potentiation (efficacy) of 810% of the current induced by 100nM GABA. Quantification of GABAA receptor mRNA in iCell Neurons revealed high levels of α5 and β3 subunits and low levels of α1, which is similar to the configuration in human neonatal brain. DISCUSSION iCell Neurons represent a new cellular model to characterize GABAergic compounds using automated patch clamp. These cells have excellent representation of cellular GABAA receptor distribution that enable determination of total small molecule efficacy and affinity as measured by cell membrane current change.
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Affiliation(s)
- Nina Y Yuan
- Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin - Milwaukee, 3210 N. Cramer Street, Milwaukee, WI 53211, United States.
| | - Michael M Poe
- Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin - Milwaukee, 3210 N. Cramer Street, Milwaukee, WI 53211, United States.
| | - Christopher Witzigmann
- Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin - Milwaukee, 3210 N. Cramer Street, Milwaukee, WI 53211, United States.
| | - James M Cook
- Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin - Milwaukee, 3210 N. Cramer Street, Milwaukee, WI 53211, United States.
| | - Douglas Stafford
- Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin - Milwaukee, 3210 N. Cramer Street, Milwaukee, WI 53211, United States.
| | - Leggy A Arnold
- Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin - Milwaukee, 3210 N. Cramer Street, Milwaukee, WI 53211, United States.
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Picones A, Loza-Huerta A, Segura-Chama P, Lara-Figueroa CO. Contribution of Automated Technologies to Ion Channel Drug Discovery. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2016; 104:357-378. [DOI: 10.1016/bs.apcsb.2016.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Wong LW, Tae HS, Cromer BA. Assembly, trafficking and function of α1β2γ2 GABAA receptors are regulated by N-terminal regions, in a subunit-specific manner. J Neurochem 2015; 134:819-32. [PMID: 26016529 DOI: 10.1111/jnc.13175] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Revised: 04/16/2015] [Accepted: 05/09/2015] [Indexed: 02/01/2023]
Abstract
GABAA receptors are pentameric ligand-gated ion channels that mediate inhibitory fast synaptic transmission in the central nervous system. Consistent with recent pentameric ligand-gated ion channels structures, sequence analysis predicts an α-helix near the N-terminus of each GABAA receptor subunit. Preceding each α-helix are 8-36 additional residues, which we term the N-terminal extension. In homomeric GABAC receptors and nicotinic acetylcholine receptors, the N-terminal α-helix is functionally essential. Here, we determined the role of the N-terminal extension and putative α-helix in heteromeric α1β2γ2 GABAA receptors. This role was most prominent in the α1 subunit, with deletion of the N-terminal extension or further deletion of the putative α-helix both dramatically reduced the number of functional receptors at the cell surface. Conversely, deletion of the β2 or γ2 N-terminal extension had little effect on the number of functional cell surface receptors. Additional deletion of the putative α-helix in the β2 or γ2 subunits did, however, decrease both functional cell surface receptors and incorporation of the γ2 subunit into mature receptors. In the β2 subunit only, α-helix deletions affected GABA sensitivity and desensitization. Our findings demonstrate that N-terminal extensions and α-helices make key subunit-specific contributions to assembly, consistent with both regions being involved in inter-subunit interactions. N-terminal α-helices and preceding sequences of eukaryotic pentameric ligand-gated ion channels are absent in prokaryotic homologues, suggesting they may not be functionally essential. Here, we show that in heteropentameric α1β2γ2 GABAA receptors, the role of these segments is highly subunit dependent. The extension preceding the α-helix in the α subunit is crucial for assembly and trafficking, but is of little importance in β and γ subunits. Indeed, robust receptor levels remain when the extension and α-helix are removed in β or γ subunits.
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Affiliation(s)
- Lik-Wei Wong
- Health Innovation Research Institute, School of Medical Sciences, RMIT University, Melbourne, Vic., Australia.,Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Vic., Australia
| | - Han-Shen Tae
- Health Innovation Research Institute, School of Medical Sciences, RMIT University, Melbourne, Vic., Australia
| | - Brett A Cromer
- Health Innovation Research Institute, School of Medical Sciences, RMIT University, Melbourne, Vic., Australia
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Wong LW, Tae HS, Cromer BA. Role of the ρ1 GABA(C) receptor N-terminus in assembly, trafficking and function. ACS Chem Neurosci 2014; 5:1266-77. [PMID: 25347026 DOI: 10.1021/cn500220t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The GABAC receptor and closely related GABAA receptor are members of the pentameric ligand-gated ion channels (pLGICs) superfamily and mediate inhibitory fast synaptic transmission in the nervous system. Each pLGIC subunit comprises an N-terminal extracellular agonist-binding domain followed by a channel domain and a variable intracellular domain. Available structural information shows that the core of the agonist-binding domain is a β sandwich of ten β-strands, which form the agonist-binding pocket at the subunit interface. This β-sandwich is preceded by an N-terminal α-helix in eukaryotic structures but not in prokaryotic structures. The N-terminal α-helix has been shown to be functionally essential in α7 nicotinic acetylcholine receptors. Sequence analysis of GABAC and GABAA receptors predicts an α-helix in a similar position but preceded by 8 to 46 additional residues, of unknown function, which we term the N-terminal extension. To test the functional role of both the N-terminal extension and the putative N-terminal α-helix in the ρ1 GABAC receptor, we created a series of deletions from the N-terminus. The N-terminal extension was not functionally essential, but its removal did reduce both cell surface expression and cooperativity of agonist-gated channel function. Further deletion of the putative N-terminal α-helix abolished receptor function by preventing cell-surface expression. Our results further demonstrate the essential role of the N-terminal α-helix in the assembly and trafficking of eukaryotic pLGICs. They also provide evidence that the N-terminal extension, although not essential, contributes to receptor assembly, trafficking and conformational changes associated with ligand gating.
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Affiliation(s)
- Lik-Wei Wong
- Health
Innovation Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia
- Department
of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Han-Shen Tae
- Health
Innovation Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia
| | - Brett A. Cromer
- Health
Innovation Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia
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