1
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Lu Y, Chen C, Zhuang D, Qian L. Molecular Dynamic Simulation To Reveal the Mechanism Underlying MGL-3196 Resistance to Thyroxine Receptor Beta. ACS OMEGA 2024; 9:20957-20965. [PMID: 38764645 PMCID: PMC11097192 DOI: 10.1021/acsomega.4c00089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/21/2024]
Abstract
Thyroxine receptor beta (TRβ) is a ligand-dependent nuclear receptor that participates in regulating multiple biological processes, particularly playing an important role in lipid metabolism regulation. TRβ is currently a popular therapeutic target for nonalcoholic steatohepatitis (NASH), while no drugs have been approved to treat this disease. MGL-3196 (Resmetirom) is the first TRβ agonist that has succeeded in phase III clinical trials for the treatment of NASH; therefore, studying its molecular mechanism of action is of great significance. In this study, we employed molecular dynamic simulation to investigate the interaction mode between MGL-3196 and TRβ at the all-atom level. More importantly, by comparing the binding patterns of MGL-3196 in several prevalent TRβ mutants, it was identified that the mutations R243Q and H435R located, respectively, around and within the ligand-binding pocket of TRβ cause TRβ to be insensitive to MGL-3196. This indicates that patients with NASH carrying these two mutations may exhibit resistance to the medication of MGL-3196, thereby highlighting the potential impact of TRβ mutations on TRβ-targeted treatment of NASH and beyond.
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Affiliation(s)
- Yi Lu
- Fujian
Key Laboratory of Neonatal Diseases, Xiamen Key Laboratory of Neonatal
Diseases, Xiamen Childreǹs Hospital
(Children’s Hospital of Fudan University at Xiamen), Xiamen 361006, China
- Department
of Pediatrics, Chidren’s Hospital
of Fudan University, Shanghai 201102, China
| | - Chun Chen
- Fujian
Key Laboratory of Neonatal Diseases, Xiamen Key Laboratory of Neonatal
Diseases, Xiamen Childreǹs Hospital
(Children’s Hospital of Fudan University at Xiamen), Xiamen 361006, China
| | - Deyi Zhuang
- Fujian
Key Laboratory of Neonatal Diseases, Xiamen Key Laboratory of Neonatal
Diseases, Xiamen Childreǹs Hospital
(Children’s Hospital of Fudan University at Xiamen), Xiamen 361006, China
| | - Liling Qian
- Fujian
Key Laboratory of Neonatal Diseases, Xiamen Key Laboratory of Neonatal
Diseases, Xiamen Childreǹs Hospital
(Children’s Hospital of Fudan University at Xiamen), Xiamen 361006, China
- Division
of Pulmonary Medicine, Shanghai Children’s Hospital, School
of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
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2
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Pagán OR. The complexities of ligand/receptor interactions: Exploring the role of molecular vibrations and quantum tunnelling. Bioessays 2024; 46:e2300195. [PMID: 38459808 DOI: 10.1002/bies.202300195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 01/19/2024] [Accepted: 02/19/2024] [Indexed: 03/10/2024]
Abstract
Molecular vibrations and quantum tunneling may link ligand binding to the function of pharmacological receptors. The well-established lock-and-key model explains a ligand's binding and recognition by a receptor; however, a general mechanism by which receptors translate binding into activation, inactivation, or modulation remains elusive. The Vibration Theory of Olfaction was proposed in the 1930s to explain this subset of receptor-mediated phenomena by correlating odorant molecular vibrations to smell, but a mechanism was lacking. In the 1990s, inelastic electron tunneling was proposed as a plausible mechanism for translating molecular vibration to odorant physiology. More recently, studies of ligands' vibrational spectra and the use of deuterated ligand analogs have provided helpful information to study this admittedly controversial hypothesis in metabotropic receptors other than olfactory receptors. In the present work, based in part on published experiments from our laboratory using planarians as an experimental organism, I will present a rationale and possible experimental approach for extending this idea to ligand-gated ion channels.
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Affiliation(s)
- Oné R Pagán
- Department of Biology, West Chester University, West Chester, Pennsylvania, USA
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3
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González-Durruthy M, Rial R, Ruso JM. Decoding the conformational binding of drug mixtures on ovalbumin: An integrated multimodal network. Int J Biol Macromol 2024; 261:129866. [PMID: 38302030 DOI: 10.1016/j.ijbiomac.2024.129866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024]
Abstract
This research addresses the crucial necessity for a deeper understanding of the binding interactions between surfactants and proteins, with a specific focus on ovalbumin. Considering ovalbumin's role in diverse biochemical processes, it remains a subject of significant interest for drug discovery and design. To fill existing knowledge gaps, we investigated the binding interaction between dicloxacillin and cetyltrimethylammonium bromide (CTAB) on ovalbumin, employing a comprehensive approach that combines computational modeling with experimental validations. Using the ezPocket tool, the computational phase predicted ten relevant binding sites on ovalbumin's surface. The isobologram combination index (CI) heatmap strongly suggested a complex interplay of antagonistic and synergistic effects. Besides, a conformational drug-drug interaction network was proposed to explore the stability of the surfactant mixture within specific binding sites of ovalbumin, revealing a dynamic landscape of suggested antagonist effects. Experimental validations through UV-vis, Fluorescence, and circular dichroism (CD) spectroscopy further corroborated the computational findings, confirming the formation of stable complexes. Finally, this study not only advances our comprehension of ovalbumin's interactions with surfactants but also offers a multidimensional perspective and an advanced methodological framework for efficient therapeutic strategies, opening new avenues for future applications in drug development and applied biochemistry.
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Affiliation(s)
- Michael González-Durruthy
- Soft Matter and Molecular Biophysics Group, Department of Applied Physics and Institute of Materials (iMATUS), University of Santiago de Compostela, 15782 Santiago de Compostela, Spain; NanoSafety Group, International Iberian Nanotechnology Laboratory, Braga 4715-330, Portugal.
| | - Ramón Rial
- Soft Matter and Molecular Biophysics Group, Department of Applied Physics and Institute of Materials (iMATUS), University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Juan M Ruso
- Soft Matter and Molecular Biophysics Group, Department of Applied Physics and Institute of Materials (iMATUS), University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
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4
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Yekefallah M, van Aalst EJ, van Beekveld RAM, Eason IR, Breukink E, Weingarth M, Wylie BJ. Cooperative Gating of a K + Channel by Unmodified Biological Anionic Lipids Viewed by Solid-State NMR Spectroscopy. J Am Chem Soc 2024; 146:4421-4432. [PMID: 38334076 PMCID: PMC10885140 DOI: 10.1021/jacs.3c09266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Lipids adhere to membrane proteins to stimulate or suppress molecular and ionic transport and signal transduction. Yet, the molecular details of lipid-protein interaction and their functional impact are poorly characterized. Here we combine NMR, coarse-grained molecular dynamics (CGMD), and functional assays to reveal classic cooperativity in the binding and subsequent activation of a bacterial inward rectifier potassium (Kir) channel by phosphatidylglycerol (PG), a common component of many membranes. Past studies of lipid activation of Kir channels focused primarily on phosphatidylinositol bisphosphate, a relatively rare signaling lipid that is tightly regulated in space and time. We use solid-state NMR to quantify the binding of unmodified 13C-PG to the K+ channel KirBac1.1 in liposomes. This specific lipid-protein interaction has a dissociation constant (Kd) of ∼7 mol percentage PG (ΧPG) with positive cooperativity (n = 3.8) and approaches saturation near 20% ΧPG. Liposomal flux assays show that K+ flux also increases with PG in a cooperative manner with an EC50 of ∼20% ΧPG, within the physiological range. Further quantitative fitting of these data reveals that PG acts as a partial (80%) agonist with fivefold K+ flux amplification. Comparisons of NMR chemical shift perturbation and CGMD simulations at different ΧPG confirm the direct interaction of PG with key residues, several of which would not be accessible to lipid headgroups in the closed state of the channel. Allosteric regulation by a common lipid is directly relevant to the activation mechanisms of several human ion channels. This study highlights the role of concentration-dependent lipid-protein interactions and tightly controlled protein allostery in the activation and regulation of ion channels.
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Affiliation(s)
- Maryam Yekefallah
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Roy A M van Beekveld
- Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, Utrecht3584 CH, The Netherlands
| | - Isaac R Eason
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Department of Chemistry, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Markus Weingarth
- Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, Utrecht3584 CH, The Netherlands
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
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5
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Moreau C, Lukačević T, Pallier A, Sobilo J, Aci-Sèche S, Garnier N, Même S, Tóth É, Lacerda S. Peptide-Conjugated MRI Probe Targeted to Netrin-1, a Novel Metastatic Breast Cancer Biomarker. Bioconjug Chem 2024; 35:265-275. [PMID: 38340041 DOI: 10.1021/acs.bioconjchem.3c00558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Despite significant progress in cancer imaging and treatment over the years, early diagnosis and metastasis detection remain a challenge. Molecular magnetic resonance imaging (MRI), with its high resolution, can be well adapted to fulfill this need, requiring the design of contrast agents which target specific tumor biomarkers. Netrin-1 is an extracellular protein overexpressed in metastatic breast cancer and implicated in tumor progression and the appearance of metastasis. This study focuses on the design and preclinical evaluation of a novel Netrin-1-specific peptide-based MRI probe, GdDOTA-KKTHDAVR (Gd-K), to visualize metastatic breast cancer. The targeting peptide sequence was identified based on the X-ray structure of the complex between Netrin-1 and its transmembrane receptor DCC. Molecular docking simulations support the probe design. In vitro studies evidenced submicromolar affinity of Gd-K for Netrin-1 (KD = 0.29 μM) and good MRI efficacy (proton relaxivity, r1 = 4.75 mM-1 s-1 at 9.4 T, 37 °C). In vivo MRI studies in a murine model of triple-negative metastatic breast cancer revealed successful tumor visualization at earlier stages of tumor development (smaller tumor volume). Excellent signal enhancement, 120% at 2 min and 70% up to 35 min post injection, was achieved (0.2 mmol/kg injected dose), representing a reasonable imaging time window and a superior contrast enhancement in the tumor as compared to Dotarem injection.
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Affiliation(s)
- Clémentine Moreau
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Tea Lukačević
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Agnès Pallier
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Julien Sobilo
- TAAM-In vivo Imaging Centre, MO2VING, CNRS UAR44, F-45071 Orléans 2, France
| | - Samia Aci-Sèche
- Institut de Chimie Organique et Analytique, UMR CNRS-Université d'Orléans 7311, Université d'Orléans BP 6759, 45067 Orléans Cedex 2, France
| | - Norbert Garnier
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Sandra Même
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Éva Tóth
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Sara Lacerda
- Centre de Biophysique Moléculaire, CNRS UPR4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France
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6
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Popović L, Wintgens JP, Wu Y, Brankatschk B, Menninger S, Degenhart C, Jensen N, Wichert SP, Klebl B, Rossner MJ, Wehr MC. Profiling of ERBB receptors and downstream pathways reveals selectivity and hidden properties of ERBB4 antagonists. iScience 2024; 27:108839. [PMID: 38303712 PMCID: PMC10831936 DOI: 10.1016/j.isci.2024.108839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/20/2023] [Accepted: 01/03/2024] [Indexed: 02/03/2024] Open
Abstract
ERBB receptor tyrosine kinases are involved in development and diseases like cancer, cardiovascular, neurodevelopmental, and mental disorders. Although existing drugs target ERBB receptors, the next generation of drugs requires enhanced selectivity and understanding of physiological pathway responses to improve efficiency and reduce side effects. To address this, we developed a multilevel barcoded reporter profiling assay, termed 'ERBBprofiler', in living cells to monitor the activity of all ERBB targets and key physiological pathways simultaneously. This assay helps differentiate on-target therapeutic effects from off-target and off-pathway side effects of ERBB antagonists. To challenge the assay, eight established ERBB antagonists were profiled. Known effects were confirmed, and previously uncharacterized properties were discovered, such as pyrotinib's preference for ERBB4 over EGFR. Additionally, two lead compounds selectively targeting ERBB4 were profiled, showing promise for clinical trials. Taken together, this multiparametric profiling approach can guide early-stage drug development and lead to improved future therapeutic interventions.
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Affiliation(s)
- Lukša Popović
- Research Group Cell Signalling, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
- Systasy Bioscience GmbH, Balanstrasse 6, 81669 Munich, Germany
| | - Jan P. Wintgens
- Research Group Cell Signalling, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
- Systasy Bioscience GmbH, Balanstrasse 6, 81669 Munich, Germany
| | - Yuxin Wu
- Research Group Cell Signalling, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
| | - Ben Brankatschk
- Systasy Bioscience GmbH, Balanstrasse 6, 81669 Munich, Germany
| | - Sascha Menninger
- Lead Discovery Center GmbH, Otto-Hahn-Strasse 15, 44227 Dortmund, Germany
| | - Carsten Degenhart
- Lead Discovery Center GmbH, Otto-Hahn-Strasse 15, 44227 Dortmund, Germany
| | - Niels Jensen
- Section of Molecular Neurobiology, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
| | - Sven P. Wichert
- Systasy Bioscience GmbH, Balanstrasse 6, 81669 Munich, Germany
- Section of Molecular Neurobiology, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
| | - Bert Klebl
- Lead Discovery Center GmbH, Otto-Hahn-Strasse 15, 44227 Dortmund, Germany
| | - Moritz J. Rossner
- Systasy Bioscience GmbH, Balanstrasse 6, 81669 Munich, Germany
- Section of Molecular Neurobiology, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
| | - Michael C. Wehr
- Research Group Cell Signalling, Department of Psychiatry and Psychotherapy, LMU University Hospital, LMU Munich, Nussbaumstrasse 7, 80336 Munich, Germany
- Systasy Bioscience GmbH, Balanstrasse 6, 81669 Munich, Germany
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7
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Buchwald P. Quantitative receptor model for responses that are left- or right-shifted versus occupancy (are more or less concentration sensitive): the SABRE approach. Front Pharmacol 2023; 14:1274065. [PMID: 38161688 PMCID: PMC10755021 DOI: 10.3389/fphar.2023.1274065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 12/05/2023] [Indexed: 01/03/2024] Open
Abstract
Simple one-to three-parameter models routinely used to fit typical dose-response curves and calculate EC50 values using the Hill or Clark equation cannot provide the full picture connecting measured response to receptor occupancy, which can be quite complex due to the interplay between partial agonism and (pathway-dependent) signal amplification. The recently introduced SABRE quantitative receptor model is the first one that explicitly includes a parameter for signal amplification (γ) in addition to those for binding affinity (K d), receptor-activation efficacy (ε), constitutive activity (ε R0), and steepness of response (Hill slope, n). It can provide a unified framework to fit complex cases, where fractional response and occupancy do not match, as well as simple ones, where parameters constrained to specific values can be used (e.g., ε R0 = 0, γ = 1, or n = 1). Here, it is shown for the first time that SABRE can fit not only typical cases where response curves are left-shifted compared to occupancy (κ = K d/EC50 > 1) due to signal amplification (γ > 1), but also less common ones where they are right-shifted (i.e., less concentration-sensitive; κ = K d/EC50 < 1) by modeling them as apparent signal attenuation/loss (γ < 1). Illustrations are provided with μ-opioid receptor (MOPr) data from three different experiments with one left- and one right-shifted response (G protein activation and β-arrestin2 recruitment, respectively; EC50,Gprt < K d < EC50,βArr). For such cases of diverging pathways with differently shifted responses, partial agonists can cause very weak responses in the less concentration-sensitive pathway without having to be biased ligands due to the combination of low ligand efficacy and signal attenuation/loss-an illustration with SABRE-fitted oliceridine data is included.
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Affiliation(s)
- Peter Buchwald
- Department of Molecular and Cellular Pharmacology, Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL, United States
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8
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Uchida Y, Kan H, Furukawa G, Onda K, Sakurai K, Takada K, Matsukawa N, Oishi K. Relationship between brain iron dynamics and blood-brain barrier function during childhood: a quantitative magnetic resonance imaging study. Fluids Barriers CNS 2023; 20:60. [PMID: 37592310 PMCID: PMC10433620 DOI: 10.1186/s12987-023-00464-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 08/14/2023] [Indexed: 08/19/2023] Open
Abstract
BACKGROUND Mounting evidence suggests that the blood-brain barrier (BBB) plays an important role in the regulation of brain iron homeostasis in normal brain development, but these imaging profiles remain to be elucidated. We aimed to establish a relationship between brain iron dynamics and BBB function during childhood using a combined quantitative magnetic resonance imaging (MRI) to depict both physiological systems along developmental trajectories. METHODS In this single-center prospective study, consecutive outpatients, 2-180 months of age, who underwent brain MRI (3.0-T scanner; Ingenia; Philips) between January 2020 and January 2021, were included. Children with histories of preterm birth or birth defects, abnormalities on MRI, and diagnoses that included neurological diseases during follow-up examinations through December 2022 were excluded. In addition to clinical MRI, quantitative susceptibility mapping (QSM; iron deposition measure) and diffusion-prepared pseudo-continuous arterial spin labeling (DP-pCASL; BBB function measure) were acquired. Atlas-based analyses for QSM and DP-pCASL were performed to investigate developmental trajectories of regional brain iron deposition and BBB function and their relationships. RESULTS A total of 78 children (mean age, 73.8 months ± 61.5 [SD]; 43 boys) were evaluated. Rapid magnetic susceptibility progression in the brain (Δsusceptibility value) was observed during the first two years (globus pallidus, 1.26 ± 0.18 [× 10- 3 ppm/month]; substantia nigra, 0.68 ± 0.16; thalamus, 0.15 ± 0.04). The scattergram between the Δsusceptibility value and the water exchange rate across the BBB (kw) divided by the cerebral blood flow was well fitted to the sigmoidal curve model, whose inflection point differed among each deep gray-matter nucleus (globus pallidus, 2.96-3.03 [mL/100 g]-1; substantia nigra, 3.12-3.15; thalamus, 3.64-3.67) in accordance with the regional heterogeneity of brain iron accumulation. CONCLUSIONS The combined quantitative MRI study of QSM and DP-pCASL for pediatric brains demonstrated the relationship between brain iron dynamics and BBB function during childhood. TRIAL REGISTRATION UMIN Clinical Trials Registry identifier: UMIN000039047, registered January 6, 2020.
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Affiliation(s)
- Yuto Uchida
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, 208 Traylor Building, 720 Rutland Avenue, Baltimore, MD, 21205, USA.
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, 1, Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Aichi, Japan.
| | - Hirohito Kan
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1- 1-20, Daiko-Minami, Higashi-ku, Nagoya, 461-8673, Aichi, Japan
| | - Gen Furukawa
- Department of Pediatrics, Fujita Health University School of Medicine, 1-98, Kutsukake-cho, Dengakugakubo, Toyoake, 470-1192, Aichi, Japan
| | - Kengo Onda
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, 208 Traylor Building, 720 Rutland Avenue, Baltimore, MD, 21205, USA
| | - Keita Sakurai
- Department of Radiology, National Center for Geriatrics and Gerontology, Morioka-cho, Obu, 474-8511, Aichi, Japan
| | - Koji Takada
- Department of Neurology, Toyokawa City Hospital, 23, Noji, Yawata-cho, Toyokawa, 442-0857, Aichi, Japan
| | - Noriyuki Matsukawa
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, 1, Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Aichi, Japan
| | - Kenichi Oishi
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, 208 Traylor Building, 720 Rutland Avenue, Baltimore, MD, 21205, USA
- The Richman Family Precision Medicine Center of Excellence in Alzheimer's Disease, Baltimore, MD, 21224, USA
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9
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Scott-Dennis M, Rafani FA, Yi Y, Perera T, Harwood CR, Guba W, Rufer AC, Grether U, Veprintsev DB, Sykes DA. Development of a membrane-based Gi-CASE biosensor assay for profiling compounds at cannabinoid receptors. Front Pharmacol 2023; 14:1158091. [PMID: 37637423 PMCID: PMC10450933 DOI: 10.3389/fphar.2023.1158091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 07/05/2023] [Indexed: 08/29/2023] Open
Abstract
Introduction: The cannabinoid receptor (CBR) subtypes 1 (CB1R) and 2 (CB2R) are key components of the endocannabinoid system (ECS), playing a central role in the control of peripheral pain, inflammation and the immune response, with further roles in the endocrine regulation of food intake and energy balance. So far, few medicines targeting these receptors have reached the clinic, suggesting that a better understanding of the receptor signalling properties of existing tool compounds and clinical candidates may open the door to the development of more effective and safer treatments. Both CB1R and CB2R are Gαi protein-coupled receptors but detecting Gαi protein signalling activity reliably and reproducibly is challenging. This is due to the inherent variability in live cell-based assays and restrictions around the use of radioactive [35S]-GTPγS, a favoured technology for developing higher-throughput membrane-based Gαi protein activity assays. Methods: Here, we describe the development of a membrane-based Gαi signalling system, produced from membrane preparations of HEK293TR cells, stably overexpressing CB1R or CB2R, and components of the Gαi-CASE biosensor. This BRET-based system allows direct detection of Gαi signalling in both cells and membranes by monitoring bioluminescence resonance energy transfer (BRET) between the α and the βγ subunits. Cells and membranes were subject to increasing concentrations of reference cannabinoid compounds, with 10 μM furimazine added to generate RET signals, which were detected on a PHERAstar FSX plate reader, then processed using MARS software and analysed in GraphPad PRISM 9.2. Results: In membranes expressing the Gi-CASE biosensor, the cannabinoid ligands profiled were found to show agonist and inverse agonist activity. Agonist activity elicited a decrease in the BRET signal, indicative of receptor activation and G protein dissociation. Inverse agonist activity caused an increase in BRET signal, indicative of receptor inactivation, and the accumulation of inactive G protein. Our membrane-based Gi-CASE NanoBRET system successfully characterised the potency (pEC50) and efficacy (Emax) of CBR agonists and inverse agonists in a 384-well screening format. Values obtained were in-line with whole-cell Gi-CASE assays and consistent with literature values obtained in the GTPγS screening format. Discussion: This novel, membrane-based Gαi protein activation assay is applicable to other Gαi-coupled GPCRs, including orphan receptors, allowing real-time higher-throughput measurements of receptor activation.
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Affiliation(s)
- Morgan Scott-Dennis
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
| | - Fikri A. Rafani
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
| | - Yicheng Yi
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
| | - Themiya Perera
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
| | - Clare R. Harwood
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
| | - Wolfgang Guba
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Arne C. Rufer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Uwe Grether
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Dmitry B. Veprintsev
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
- Z7 Biotech Limited, London, United Kingdom
| | - David A. Sykes
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), University of Nottingham, Midlands, United Kingdom
- Z7 Biotech Limited, London, United Kingdom
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10
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Blaine AT, van Rijn RM. Receptor expression and signaling properties in the brain, and structural ligand motifs that contribute to delta opioid receptor agonist-induced seizures. Neuropharmacology 2023; 232:109526. [PMID: 37004753 PMCID: PMC11078570 DOI: 10.1016/j.neuropharm.2023.109526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 03/10/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
The δ opioid receptor (δOR) is a therapeutic target for the treatment of various neurological disorders, such as migraines, chronic pain, alcohol use, and mood disorders. Relative to μ opioid receptor agonists, δOR agonists show lower abuse liability and may be potentially safer analgesic alternatives. However, currently no δOR agonists are approved for clinical use. A small number of δOR agonists reached Phase II trials, but ultimately failed to progress due to lack of efficacy. One side effect of δOR agonism that remains poorly understood is the ability of δOR agonists to produce seizures. The lack of a clear mechanism of action is partly driven by the fact that δOR agonists range in their propensity to induce seizure behavior, with multiple δOR agonists reportedly not causing seizures. There is a significant gap in our current understanding of why certain δOR agonists are more likely to induce seizures, and what signal-transduction pathway and/or brain area is engaged to produce these seizures. In this review we provide a comprehensive overview of the current state of knowledge of δOR agonist-mediated seizures. The review was structured to highlight which agonists produce seizures, which brain regions have been implicated and which signaling mediators have been examined in this behavior. Our hope is that this review will spur future studies that are carefully designed and aimed to solve the question why certain δOR agonists are seizurogenic. Obtaining such insight may expedite the development of novel δOR clinical candidates without the risk of inducing seizures. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".
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Affiliation(s)
- Arryn T Blaine
- Purdue University, Department of Medicinal Chemistry and Molecular Pharmacology, West Lafayette, IN, 47907, USA; Purdue University Interdisciplinary Life Science graduate program, West Lafayette, IN, 47907, USA
| | - Richard M van Rijn
- Purdue University, Department of Medicinal Chemistry and Molecular Pharmacology, West Lafayette, IN, 47907, USA; Purdue Institute for Integrative Neuroscience, West Lafayette, IN, 47907, USA; Purdue Institute for Drug Discovery, West Lafayette, IN, 47907, USA; Septerna Inc., South San Francisco, CA, 94080, USA.
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11
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Rajanathan R, Riera CVI, Pedersen TM, Staehr C, Bouzinova EV, Nyengaard JR, Thomsen MB, Bøtker HE, Matchkov VV. Hypercontractile Cardiac Phenotype in Mice with Migraine-Associated Mutation in the Na +,K +-ATPase α 2-Isoform. Cells 2023; 12:cells12081108. [PMID: 37190017 DOI: 10.3390/cells12081108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/03/2023] [Accepted: 04/05/2023] [Indexed: 05/17/2023] Open
Abstract
Two α-isoforms of the Na+,K+-ATPase (α1 and α2) are expressed in the cardiovascular system, and it is unclear which isoform is the preferential regulator of contractility. Mice heterozygous for the familial hemiplegic migraine type 2 (FHM2) associated mutation in the α2-isoform (G301R; α2+/G301R mice) have decreased expression of cardiac α2-isoform but elevated expression of the α1-isoform. We aimed to investigate the contribution of the α2-isoform function to the cardiac phenotype of α2+/G301R hearts. We hypothesized that α2+/G301R hearts exhibit greater contractility due to reduced expression of cardiac α2-isoform. Variables for contractility and relaxation of isolated hearts were assessed in the Langendorff system without and in the presence of ouabain (1 µM). Atrial pacing was performed to investigate rate-dependent changes. The α2+/G301R hearts displayed greater contractility than WT hearts during sinus rhythm, which was rate-dependent. The inotropic effect of ouabain was more augmented in α2+/G301R hearts than in WT hearts during sinus rhythm and atrial pacing. In conclusion, cardiac contractility was greater in α2+/G301R hearts than in WT hearts under resting conditions. The inotropic effect of ouabain was rate-independent and enhanced in α2+/G301R hearts, which was associated with increased systolic work.
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Affiliation(s)
| | - Clàudia Vilaseca I Riera
- Department of Basic Science, School of Medicine and Health Sciences, International University of Catalonia, 08195 Barcelona, Spain
| | | | - Christian Staehr
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | | | - Jens Randel Nyengaard
- Department of Clinical Medicine, Core Center for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, 8000 Aarhus, Denmark
- Department of Pathology, Aarhus University Hospital, 8200 Aarhus, Denmark
| | - Morten B Thomsen
- Biomedical Sciences, University of Copenhagen, 1168 Copenhagen, Denmark
| | - Hans Erik Bøtker
- Department of Cardiology, Aarhus University Hospital, 8200 Aarhus, Denmark
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12
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Quantification of receptor binding from response data obtained at different receptor levels: a simple individual sigmoid fitting and a unified SABRE approach. Sci Rep 2022; 12:18833. [PMID: 36336760 PMCID: PMC9637741 DOI: 10.1038/s41598-022-23588-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/02/2022] [Indexed: 11/07/2022] Open
Abstract
Methods that allow quantification of receptor binding (occupancy) by measuring response (effect) data only are of interest as they can be used to allow characterization of binding properties (e.g., dissociation constant, Kd) without having to perform explicit ligand binding experiments that require different setups (e.g., use of labeled ligands). However, since response depends not just on the binding affinity-determined receptor occupancy, but also on receptor activation, which is affected by ligand efficacy (plus constitutive activity, if present), and downstream pathway amplification, this requires the acquisition and fitting of multiple concentration-response data. Here, two alternative methods, which both are straightforward to implement using nonlinear regression software, are described to fit such multiple responses measured at different receptor levels that can be obtained, for example, by partial irreversible receptor inactivation (i.e., Furchgott method) or different expression levels. One is a simple method via straightforward fitting of each response with sigmoid functions and estimation of Kd from the obtained Emax and EC50 values as Kd = (Emax·EC'50 - E'max·EC50)/(Emax - E'max). This is less error-prone than the original Furchgott method of double-reciprocal fit and simpler than alternatives that require concentration interpolations, thus, should allow more widespread use of this so-far underutilized approach to estimate binding properties. Relative efficacies can then be compared using Emax·Kd/EC50 values. The other is a complex method that uses the SABRE receptor model to obtain a unified fit of the multiple concentration-response curves with a single set of parameters that include binding affinity Kd, efficacy ε, amplification γ, and Hill coefficient n. Illustrations with simulated and experimental data are presented including with activity data of three muscarinic agonists measured in rabbit myocardium.
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13
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Jakubík J, Randáková A. Insights into the operational model of agonism of receptor dimers. Expert Opin Drug Discov 2022; 17:1181-1191. [PMID: 36369915 DOI: 10.1080/17460441.2023.2147502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 11/10/2022] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Accurate ranking of efficacies and potencies of agonists is essential in the discovery of new selective agonists. For the purpose of system-independent ranking of agonists, the operational model of agonism (OMA) has become a standard. Many receptors function as oligomers which makes functional responses more complex, requiring an extension of the original OMA. AREAS COVERED Explicit equations of the operational model of agonism of receptor dimers (OMARD) were derived. The OMARD can be applied to any receptor possessing two orthosteric sites. The behavior of OMARD was analyzed to demonstrate its complexity and relation to experimental data. Properties of OMARD and OMA equations were compared to demonstrate their pros and cons. EXPERT OPINION Extension of OMA by slope factors gives simple equations of functional response that are easy to fit experimental data but results may be inaccurate because of exponentiation of operational efficacy. Also, such equations cannot accommodate bell-shaped curves. Explicit equations of OMARD give accurate results but are complex and tedious to fit experimental data. All operational models use inter-dependent parameters that are a hurdle in the fitting. A good understanding of OMARD behavior helps to overcome such obstacles.
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Affiliation(s)
- Jan Jakubík
- Laboratory of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
| | - Alena Randáková
- Laboratory of Neurochemistry, Institute of Physiology CAS, Prague, Czech Republic
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14
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Ding Q, Chorazyczewski J, Gros R, Motulsky HJ, Limbird LE, Feldman RD. Correlation of functional and radioligand binding characteristics of GPER ligands confirming aldosterone as a GPER agonist. Pharmacol Res Perspect 2022; 10:e00995. [PMID: 36065843 PMCID: PMC9446082 DOI: 10.1002/prp2.995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 11/30/2022] Open
Abstract
Aldosterone exerts some of its effects not by binding to mineralocorticoid receptors, but rather by acting via G protein-coupled estrogen receptors (GPER). To determine if aldosterone binds directly to GPER, we studied the ability of aldosterone to compete for the binding of [3 H] 2-methoxyestradiol ([3 H] 2-ME), a high potency GPER-selective agonist. We used GPER gene transfer to engineer Sf9-cultured insect cells to express GPER. We chose insect cells to avoid interactions with any intrinsic mammalian receptors for aldosterone. [3 H] 2-ME binding was saturable and reversible to a high-affinity population of receptors with Kd = 3.7 nM and Bmax = 2.2 pmol/mg. Consistent with agonist binding to G Protein-coupled receptors, [3 H] 2-ME high-affinity state binding was reduced in the presence of the hydrolysis-resistant GTP analog, GppNHp. [3 H] 2-ME binding was competed for by the GPER agonist G1, the GPER antagonist G15, estradiol (E2), as well as aldosterone (Aldo). The order of potency for competing for [3 H] 2-ME binding, namely 2ME > Aldo > E2 ≥ G1, paralleled the orders of potency for inhibition of cell proliferation and inhibition of ERK phosphorylation by ligands acting at GPER. These data confirm the ability of aldosterone to interact with the GPER, consistent with the interpretation that aldosterone likely mediates its GPER-dependent effects by direct binding to the GPER. SIGNIFICANCE STATEMENT: Despite the growing evidence for aldosterone's actions via G protein-coupled estrogen receptors (GPER), there remains significant skepticism that aldosterone can directly interact with GPER. The current studies are the first to demonstrate directly that aldosterone indeed is capable of binding to the GPER and thus likely mediates its GPER-dependent effects by direct binding to the receptor.
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Affiliation(s)
- Qingming Ding
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, Winnipeg, Canada
| | - Jozef Chorazyczewski
- Departments of Medicine, Physiology and Pharmacology, Robarts Research Institute, London, Canada
| | - Robert Gros
- Departments of Medicine, Physiology and Pharmacology, Robarts Research Institute, London, Canada
| | | | - Lee E Limbird
- Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee, USA
| | - Ross D Feldman
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, Winnipeg, Canada
- Departments of Medicine, Physiology and Pharmacology, Robarts Research Institute, London, Canada
- Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, Canada
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15
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Razidlo JA, Fausner SML, Ingebretson AE, Wang LC, Petersen CL, Mirza S, Swank IN, Alvarez VA, Lemos JC. Chronic Loss of Muscarinic M5 Receptor Function Manifests Disparate Impairments in Exploratory Behavior in Male and Female Mice despite Common Dopamine Regulation. J Neurosci 2022; 42:6917-6930. [PMID: 35896424 PMCID: PMC9463982 DOI: 10.1523/jneurosci.1424-21.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 06/09/2022] [Accepted: 07/19/2022] [Indexed: 11/21/2022] Open
Abstract
There are five cloned muscarinic acetylcholine receptors (M1-M5). Of these, the muscarinic type 5 receptor (M5) is the only one localized to dopamine neurons in the ventral tegmental area and substantia nigra. Unlike M1-M4, the M5 receptor has relatively restricted expression in the brain, making it an attractive therapeutic target. Here, we performed an in-depth characterization of M5-dependent potentiation of dopamine transmission in the nucleus accumbens and accompanying exploratory behaviors in male and female mice. We show that M5 receptors potentiate dopamine transmission by acting directly on the terminals within the nucleus accumbens. Using the muscarinic agonist oxotremorine, we revealed a unique concentration-response curve and a sensitivity to repeated forced swim stress or restraint stress exposure. We found that constitutive deletion of M5 receptors reduced exploration of the center of an open field while at the same time impairing normal habituation only in male mice. In addition, M5 deletion reduced exploration of salient stimuli, especially under conditions of high novelty, yet had no effect on hedonia assayed using the sucrose preference test or on stress-coping strategy assayed using the forced swim test. We conclude that M5 receptors are critical for both engaging with the environment and updating behavioral output in response to environment cues, specifically in male mice. A cardinal feature of mood and anxiety disorders is withdrawal from the environment. These data indicate that boosting M5 receptor activity may be a useful therapeutic target for ameliorating these symptoms of depression and anxiety.SIGNIFICANCE STATEMENT The basic physiological and behavioral functions of the muscarinic M5 receptor remain understudied. Furthermore, its presence on dopamine neurons, relatively restricted expression in the brain, and recent crystallization make it an attractive target for therapeutic development. Yet, most preclinical studies of M5 receptor function have primarily focused on substance use disorders in male rodents. Here, we characterized the role of M5 receptors in potentiating dopamine transmission in the nucleus accumbens, finding impaired functioning after stress exposure. Furthermore, we show that M5 receptors can modulate exploratory behavior in a sex-specific manner, without affecting hedonic behavior. These findings further illustrate the therapeutic potential of the M5 receptor, warranting further research in the context of treating mood disorders.
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Affiliation(s)
- John A Razidlo
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Skylar M L Fausner
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Anna E Ingebretson
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Liuchang C Wang
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Christopher L Petersen
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Salahudeen Mirza
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Isabella N Swank
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
| | - Veronica A Alvarez
- Laboratory on Neurobiology of Compulsive Behaviors, Intramural Research Program, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-9411
| | - Julia C Lemos
- Department of Neuroscience, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
- Medical Discovery Team on Addiction, Medical School, University of Minnesota, Minneapolis, Minnesota 55455
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16
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Wang ZJ, Thomson M. Localization of signaling receptors maximizes cellular information acquisition in spatially structured natural environments. Cell Syst 2022; 13:530-546.e12. [PMID: 35679857 DOI: 10.1016/j.cels.2022.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/08/2022] [Accepted: 05/12/2022] [Indexed: 01/25/2023]
Abstract
Cells in natural environments, such as tissue or soil, sense and respond to extracellular ligands with intricately structured and non-monotonic spatial distributions, sculpted by processes such as fluid flow and substrate adhesion. In this work, we show that spatial sensing and navigation can be optimized by adapting the spatial organization of signaling pathways to the spatial structure of the environment. We develop an information-theoretic framework for computing the optimal spatial organization of a sensing system for a given signaling environment. We find that receptor localization previously observed in cells maximizes information acquisition in simulated natural contexts, including tissue and soil. Specifically, information acquisition is maximized when receptors form localized patches at regions of maximal ligand concentration. Receptor localization extends naturally to produce a dynamic protocol for continuously redistributing signaling receptors, which when implemented using simple feedback, boosts cell navigation efficiency by 30-fold.
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Affiliation(s)
- Zitong Jerry Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Matt Thomson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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17
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Dunlap T, Cao Y. Physiological Considerations for Modeling in vivo Antibody-Target Interactions. Front Pharmacol 2022; 13:856961. [PMID: 35281913 PMCID: PMC8912916 DOI: 10.3389/fphar.2022.856961] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/10/2022] [Indexed: 11/25/2022] Open
Abstract
The number of therapeutic antibodies in development pipelines is increasing rapidly. Despite superior success rates relative to small molecules, therapeutic antibodies still face many unique development challenges. There is often a translational gap from their high target affinity and specificity to the therapeutic effects. Tissue microenvironment and physiology critically influence antibody-target interactions contributing to apparent affinity alterations and dynamic target engagement. The full potential of therapeutic antibodies will be further realized by contextualizing antibody-target interactions under physiological conditions. Here we review how local physiology such as physical stress, biological fluid, and membrane characteristics could influence antibody-target association, dissociation, and apparent affinity. These physiological factors in the early development of therapeutic antibodies are valuable toward rational antibody engineering, preclinical candidate selection, and lead optimization.
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Affiliation(s)
- Tyler Dunlap
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Yanguang Cao
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.,Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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18
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Drug Design Targeting the Muscarinic Receptors and the Implications in Central Nervous System Disorders. Biomedicines 2022; 10:biomedicines10020398. [PMID: 35203607 PMCID: PMC8962391 DOI: 10.3390/biomedicines10020398] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 11/16/2022] Open
Abstract
There is substantial evidence that cholinergic system function impairment plays a significant role in many central nervous system (CNS) disorders. During the past three decades, muscarinic receptors (mAChRs) have been implicated in various pathologies and have been prominent targets of drug-design efforts. However, due to the high sequence homology of the orthosteric binding site, many drug candidates resulted in limited clinical success. Although several advances in treating peripheral pathologies have been achieved, targeting CNS pathologies remains challenging for researchers. Nevertheless, significant progress has been made in recent years to develop functionally selective orthosteric and allosteric ligands targeting the mAChRs with limited side effect profiles. This review highlights past efforts and focuses on recent advances in drug design targeting these receptors for Alzheimer’s disease (AD), schizophrenia (SZ), and depression.
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19
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Szalai L, Sziráki A, Erdélyi LS, Kovács KB, Tóth M, Tóth AD, Turu G, Bonnet D, Mouillac B, Hunyady L, Balla A. Functional Rescue of a Nephrogenic Diabetes Insipidus Causing Mutation in the V2 Vasopressin Receptor by Specific Antagonist and Agonist Pharmacochaperones. Front Pharmacol 2022; 13:811836. [PMID: 35153784 PMCID: PMC8829706 DOI: 10.3389/fphar.2022.811836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/12/2022] [Indexed: 11/25/2022] Open
Abstract
The urine concentrating function of the kidney is essential to maintain the water homeostasis of the human body. It is mainly regulated by the arginine-vasopressin (AVP), which targets the type 2 vasopressin receptor (V2R) in the kidney. The inability of V2R to respond to AVP stimulation leads to decreased urine concentration and congenital nephrogenic diabetes insipidus (NDI). NDI is characterized by polyuria, polydipsia, and hyposthenuria. In this study, we identified a point mutation (S127F) in the AVPR2 gene of an NDI patient, and we characterized the impaired function of the V2R mutant in HEK293 cells. Based on our data, the S127F-V2R mutant is almost exclusively located intracellularly in the endoplasmic reticulum (ER), and very few receptors were detected at the cell surface, where the receptor can bind to AVP. The overexpressed S127F-V2R mutant receptor has negligible cAMP generation capability compared to the wild-type receptor in response to AVP stimulation. Since certain misfolded mutant proteins, that are retained in the ER, can be rescued by pharmacological chaperones, we examined the potential rescue effects of two pharmacochaperones on the S127F-V2R. We found that pretreatment with both tolvaptan (an established V2R inverse agonist) and MCF14 compound (a cell-permeable high-affinity agonist for the V2R) were capable of partially restoring the cAMP generating function of the receptor in response to vasopressin stimulation. According to our data, both cell permeant agonists and antagonists can function as pharmacochaperones, and serve as the starting compounds to develop medicines for patients carrying the S127F mutation.
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Affiliation(s)
- Laura Szalai
- Department of Physiology, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network and Semmelweis University, Budapest, Hungary
| | - András Sziráki
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | | | | | - Miklós Tóth
- Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - András Dávid Tóth
- Department of Physiology, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network and Semmelweis University, Budapest, Hungary
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Gábor Turu
- Department of Physiology, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network and Semmelweis University, Budapest, Hungary
| | - Dominique Bonnet
- Laboratoire D'Innovation Thérapeutique, Strasbourg Drug Discovery and Development Institute (IMS), UMR7200 CNRS, Université de Strasbourg, Illkirch-Graffenstaden, France
| | - Bernard Mouillac
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - László Hunyady
- Department of Physiology, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network and Semmelweis University, Budapest, Hungary
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
- *Correspondence: László Hunyady, ; András Balla,
| | - András Balla
- Department of Physiology, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network and Semmelweis University, Budapest, Hungary
- *Correspondence: László Hunyady, ; András Balla,
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Kuwashima Y, Yanagawa M, Abe M, Hiroshima M, Ueda M, Arita M, Sako Y. Comparative Analysis of Single-Molecule Dynamics of TRPV1 and TRPV4 Channels in Living Cells. Int J Mol Sci 2021; 22:ijms22168473. [PMID: 34445178 PMCID: PMC8395219 DOI: 10.3390/ijms22168473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/28/2021] [Accepted: 08/03/2021] [Indexed: 12/27/2022] Open
Abstract
TRPV1 and TRPV4, members of the transient receptor potential vanilloid family, are multimodal ion channels activated by various stimuli, including temperature and chemicals. It has been demonstrated that TRPV channels function as tetramers; however, the dynamics of the diffusion, oligomerization, and endocytosis of these channels in living cells are unclear. Here we undertook single-molecule time-lapse imaging of TRPV1 and TRPV4 in HEK 293 cells. Differences were observed between TRPV1 and TRPV4 before and after agonist stimulation. In the resting state, TRPV4 was more likely to form higher-order oligomers within immobile membrane domains than TRPV1. TRPV1 became immobile after capsaicin stimulation, followed by its gradual endocytosis. In contrast, TRPV4 was rapidly internalized upon stimulation with GSK1016790A. The selective loss of immobile higher-order oligomers from the cell surface through endocytosis increased the proportion of the fast-diffusing state for both subtypes. With the increase in the fast state, the association rate constants of TRPV1 and TRPV4 increased, regenerating the higher-order oligomers. Our results provide a possible mechanism for the different rates of endocytosis of TRPV1 and TRPV4 based on the spatial organization of the higher-order structures of the two TRPV channels.
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Affiliation(s)
- Yutaro Kuwashima
- Cellular Informatics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako 351-0198, Saitama, Japan; (Y.K.); (M.A.); (M.H.)
- Division of Physiological Chemistry and Metabolism, Keio University Faculty of Pharmacy, Tokyo 105-0011, Japan;
| | - Masataka Yanagawa
- Cellular Informatics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako 351-0198, Saitama, Japan; (Y.K.); (M.A.); (M.H.)
- Japan Science and Technology Agency (JST), PRESTO, 4-1-8, Honcho, Kawaguchi 332-0012, Saitama, Japan
- Correspondence: (M.Y.); (Y.S.)
| | - Mitsuhiro Abe
- Cellular Informatics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako 351-0198, Saitama, Japan; (Y.K.); (M.A.); (M.H.)
| | - Michio Hiroshima
- Cellular Informatics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako 351-0198, Saitama, Japan; (Y.K.); (M.A.); (M.H.)
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR), 6-2-3, Furuedai, Suita 565-0874, Osaka, Japan;
| | - Masahiro Ueda
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR), 6-2-3, Furuedai, Suita 565-0874, Osaka, Japan;
- Laboratory of Single Molecule Biology, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Osaka, Japan
| | - Makoto Arita
- Division of Physiological Chemistry and Metabolism, Keio University Faculty of Pharmacy, Tokyo 105-0011, Japan;
- Laboratory for Metabolomics, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama 230-0045, Kanagawa, Japan
- Cellular and Molecular Epigenetics Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama 230-0045, Kanagawa, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako 351-0198, Saitama, Japan; (Y.K.); (M.A.); (M.H.)
- Correspondence: (M.Y.); (Y.S.)
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Guieu R, Brignole M, Deharo JC, Deharo P, Mottola G, Groppelli A, Paganelli F, Ruf J. Adenosine Receptor Reserve and Long-Term Potentiation: Unconventional Adaptive Mechanisms in Cardiovascular Diseases? Int J Mol Sci 2021; 22:ijms22147584. [PMID: 34299203 PMCID: PMC8303608 DOI: 10.3390/ijms22147584] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 12/12/2022] Open
Abstract
While the concept of a receptor reserve (spare receptors) is old, their presence on human cells as an adaptive mechanism in cardiovascular disease is a new suggestion. The presence of spare receptors is suspected when the activation of a weak fraction of receptors leads to maximal biological effects, in other words, when the half-maximal effective concentration (EC50) for a biological effect (cAMP production, for example) is lower than the affinity (KD) of the ligand for a receptor. Adenosine is an ATP derivative that strongly impacts the cardiovascular system via its four membrane receptors, named A1R, A2AR, A2BR, and A3R, with the A1R being more particularly involved in heart rhythm, while the A2AR controls vasodilation. After a general description of the tools necessary to explore the presence of spare receptors, this review focuses on the consequences of the presence of spare adenosine receptors in cardiovascular physiopathology. Finally, the role of the adenosinergic system in the long-term potentiation and its possible consequences on the physiopathology are also mentioned.
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Affiliation(s)
- Régis Guieu
- Center for CardioVascular and Nutrition Research, INSERM, INRAE, Aix-Marseille University, 13005 Marseille, France; (J.C.D.); (P.D.); (G.M.); (F.P.); (J.R.)
- Laboratory of Biochemistry, Assistance Publique des Hopitaux, 13005 Marseille, France
- Correspondence: ; Tel.: +33-491-385-650
| | - Michele Brignole
- IRCCS, Istituto Auxologico Italiano, Ospedale San Luca, 13000 Milan, Italy;
| | - Jean Claude Deharo
- Center for CardioVascular and Nutrition Research, INSERM, INRAE, Aix-Marseille University, 13005 Marseille, France; (J.C.D.); (P.D.); (G.M.); (F.P.); (J.R.)
- Department of Cardiology, CHU Timone, 13005 Marseille, France
| | - Pierre Deharo
- Center for CardioVascular and Nutrition Research, INSERM, INRAE, Aix-Marseille University, 13005 Marseille, France; (J.C.D.); (P.D.); (G.M.); (F.P.); (J.R.)
- Department of Cardiology, CHU Timone, 13005 Marseille, France
| | - Giovanna Mottola
- Center for CardioVascular and Nutrition Research, INSERM, INRAE, Aix-Marseille University, 13005 Marseille, France; (J.C.D.); (P.D.); (G.M.); (F.P.); (J.R.)
- Laboratory of Biochemistry, Assistance Publique des Hopitaux, 13005 Marseille, France
| | | | - Franck Paganelli
- Center for CardioVascular and Nutrition Research, INSERM, INRAE, Aix-Marseille University, 13005 Marseille, France; (J.C.D.); (P.D.); (G.M.); (F.P.); (J.R.)
- Department of Cardiovascular, Neural and Metabolic Sciences, Faint & Fall Programme, IRCCS Istituto Auxologico Italiano, San Luca Hospital, 13000 Milan, Italy
| | - Jean Ruf
- Center for CardioVascular and Nutrition Research, INSERM, INRAE, Aix-Marseille University, 13005 Marseille, France; (J.C.D.); (P.D.); (G.M.); (F.P.); (J.R.)
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22
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Hill R, Canals M. Experimental considerations for the assessment of in vivo and in vitro opioid pharmacology. Pharmacol Ther 2021; 230:107961. [PMID: 34256067 DOI: 10.1016/j.pharmthera.2021.107961] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/21/2021] [Accepted: 07/06/2021] [Indexed: 12/15/2022]
Abstract
Morphine and other mu-opioid receptor (MOR) agonists remain the mainstay treatment of acute and prolonged pain states worldwide. The major limiting factor for continued use of these current opioids is the high incidence of side effects that result in loss of life and loss of quality of life. The development of novel opioids bereft, or much less potent, at inducing these side effects remains an intensive area of research, with multiple pharmacological strategies being explored. However, as with many G protein-coupled receptors (GPCRs), translation of promising candidates from in vitro characterisation to successful clinical candidates still represents a major challenge and attrition point. This review summarises the preclinical animal models used to evaluate the key opioid-induced behaviours of antinociception, respiratory depression, constipation and opioid-induced hyperalgesia and tolerance. We highlight the influence of distinct variables in the experimental protocols, as well as the potential implications for differences in receptor reserve in each system. Finally, we discuss how methods to assess opioid action in vivo and in vitro relate to each other in the context of bridging the translational gap in opioid drug discovery.
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Affiliation(s)
- Rob Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom; Centre of Membrane Protein and Receptors, Universities of Birmingham and Nottingham, Midlands, United Kingdom.
| | - Meritxell Canals
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom; Centre of Membrane Protein and Receptors, Universities of Birmingham and Nottingham, Midlands, United Kingdom.
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23
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Webster L, Gudin J, Raffa RB, Kuchera J, Rauck R, Fudin J, Adler J, Mallick-Searle T. Understanding Buprenorphine for Use in Chronic Pain: Expert Opinion. PAIN MEDICINE 2021; 21:714-723. [PMID: 31917418 PMCID: PMC7139205 DOI: 10.1093/pm/pnz356] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Objective An expert panel convened to reach a consensus on common misconceptions surrounding buprenorphine, a Schedule III partial µ-opioid receptor agonist indicated for chronic pain. The panel also provided clinical recommendations on the appropriate use of buprenorphine and conversion strategies for switching to buprenorphine from a full µ-opioid receptor agonist for chronic pain management. Methods The consensus panel met on March 25, 2019, to discuss relevant literature and provide recommendations on interpreting buprenorphine as a partial µ-opioid receptor agonist, prescribing buprenorphine before some Schedule II, III, or IV options, perioperative/trauma management of patients taking buprenorphine, and converting patients from a full µ-opioid receptor agonist to buprenorphine. Results The panel recommended that buprenorphine’s classification as a partial µ-opioid receptor agonist not be clinically translated to mean partial analgesic efficacy. The panel also recommended that buprenorphine be considered before some Schedule II, III, or IV opioids in patients with a favorable risk/benefit profile on the basis of metabolic factors, abuse potential, and tolerability and that buprenorphine be continued during the perioperative/trauma period. In addition, switching patients from a full µ-opioid receptor agonist to buprenorphine should be considered with no weaning period at starting doses that are based on the previous opioid dose. Conclusions These recommendations provide a framework for clinicians to address most clinical scenarios regarding buprenorphine use. The overall consensus of the panel was that buprenorphine is a unique Schedule III opioid with favorable pharmacologic properties and a safety profile that may be desirable for chronic pain management.
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Affiliation(s)
| | - Jeffrey Gudin
- Department of Anesthesiology and Pain Management, Englewood Hospital and Medical Center, Englewood, New Jersey; Rutgers New Jersey Medical School, Newark, New Jersey
| | - Robert B Raffa
- College of Pharmacy, The University of Arizona Health Sciences, Tucson, Arizona.,Temple University School of Pharmacy, Philadelphia, Pennsylvania; Neumentum Inc, Palo Alto, California
| | - Jay Kuchera
- Resolute Pain Solutions, Okeechobee, Florida
| | - Richard Rauck
- Carolinas Pain Institute, Winston-Salem, North Carolina
| | - Jeffrey Fudin
- Remitigate LLC, Delmar, New York; Western New England University College of Pharmacy, Springfield, Massachusetts.,Albany College of Pharmacy & Health Sciences, Albany, New York
| | - Jeremy Adler
- Pacific Pain Medicine Consultants, Encinitas, California
| | - Theresa Mallick-Searle
- Division of Pain Medicine, Stanford Medicine Outpatient Center, Redwood City, California, USA
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24
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Abstract
Cannabinoid receptors, located throughout the body, are part of the endocannabinoid system. Cannabinoid CB1 and CB2 receptors are G protein-coupled receptors present from the early stages of gestation, which is involved in various physiological processes, including appetite, pain-sensation, mood, and memory. Due to the lipophilic nature of cannabinoids, it was initially thought that these compounds exert several biological effects by disrupting the cell membrane nonspecifically. Recent biochemical and behavioral findings have demonstrated that blockade of CB1 receptors engenders antidepressant-like neurochemical changes (increases in extracellular levels of monoamines in cortical but not subcortical brain regions) and behavioral effects consistent with antidepressant/antistress activity. We aim to define various roles of cannabinoid receptors in modulating signaling pathways and association with several pathophysiological conditions.
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25
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Abstract
Engineered biocircuits designed with biological components have the capacity to expand and augment living functions. Here we demonstrate that proteases can be integrated into digital or analog biocircuits to process biological information. We first construct peptide-caged liposomes that treat protease activity as two-valued (i.e., signal is 0 or 1) operations to construct the biological equivalent of Boolean logic gates, comparators and analog-to-digital converters. We use these modules to assemble a cell-free biocircuit that can combine with bacteria-containing blood, quantify bacteria burden, and then calculate and unlock a selective drug dose. By contrast, we treat protease activity as multi-valued (i.e., signal is between 0 and 1) by controlling the degree to which a pool of enzymes is shared between two target substrates. We perform operations on these analog values by manipulating substrate concentrations and combine these operations to solve the mathematical problem Learning Parity with Noise (LPN). These results show that protease activity can be used to process biological information by binary Boolean logic, or as multi-valued analog signals under conditions where substrate resources are shared.
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Affiliation(s)
- Brandon Alexander Holt
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech College of Engineering and Emory School of Medicine, Atlanta, GA, 30332, USA
| | - Gabriel A Kwong
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech College of Engineering and Emory School of Medicine, Atlanta, GA, 30332, USA.
- Parker H. Petit Institute of Bioengineering and Bioscience, Atlanta, GA, 30332, USA.
- Institute for Electronics and Nanotechnology, Georgia Tech, Atlanta, GA, 30332, USA.
- Integrated Cancer Research Center, Georgia Tech, Atlanta, GA, 30332, USA.
- The Georgia Immunoengineering Consortium, Emory University and Georgia Tech, Atlanta, GA, 30332, USA.
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26
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Buchwald P. A single unified model for fitting simple to complex receptor response data. Sci Rep 2020; 10:13386. [PMID: 32770075 PMCID: PMC7414914 DOI: 10.1038/s41598-020-70220-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022] Open
Abstract
The fitting of complex receptor-response data where fractional response and occupancy do not match is challenging. They encompass important cases including (a) the presence of "receptor reserve" and/or partial agonism, (b) multiple responses assessed at different vantage points along a pathway, (c) responses that are different along diverging downstream pathways (biased agonism), and (d) constitutive activity. For these, simple models such as the well-known Clark or Hill equations cannot be used. Those that can, such as the operational (Black&Leff) model, do not provide a unified approach, have multiple nonintuitive parameters that are challenging to fit in well-defined manner, have difficulties incorporating binding data, and cannot be reduced or connected to simpler forms. We have recently introduced a quantitative receptor model (SABRE) that includes parameters for Signal Amplification (γ), Binding affinity (Kd), Receptor activation Efficacy (ε), and constitutive activity (εR0). It provides a single equation to fit complex cases within a full two-state framework with the possibility of incorporating receptor occupancy data (i.e., experimental Kds). Simpler cases can be fit by using consecutively reduced forms obtained by constraining parameters to specific values, e.g., εR0 = 0: no constitutive activity, γ = 1: no amplification (Emax-type fitting), and ε = 1: no partial agonism (Clark equation). Here, a Hill-type extension is introduced (n ≠ 1), and simulated and experimental receptor-response data from simple to increasingly complex cases are fitted within the unified framework of SABRE with differently constrained parameters.
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Affiliation(s)
- Peter Buchwald
- Department of Molecular and Cellular Pharmacology and Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL, 33136, USA.
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Accuracy and Precision of the Receptorial Responsiveness Method (RRM) in the Quantification of A 1 Adenosine Receptor Agonists. Int J Mol Sci 2019; 20:ijms20246264. [PMID: 31842299 PMCID: PMC6940880 DOI: 10.3390/ijms20246264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/07/2019] [Accepted: 12/09/2019] [Indexed: 12/17/2022] Open
Abstract
The receptorial responsiveness method (RRM) is a procedure that is based on a simple nonlinear regression while using a model with two variables (X, Y) and (at least) one parameter to be determined (cx). The model of RRM describes the co-action of two agonists that consume the same response capacity (due to the use of the same postreceptorial signaling in a biological system). While using RRM, uniquely, an acute increase in the concentration of an agonist (near the receptors) can be quantified (as cx), via evaluating E/c curves that were constructed with the same or another agonist in the same system. As this measurement is sensitive to the implementation of the curve fitting, the goal of the present study was to test RRM by combining different ways and setting options, namely: individual vs. global fitting, ordinary vs. robust fitting, and three weighting options (no weighting vs. weighting by 1/Y2 vs. weighting by 1/SD2). During the testing, RRM was used to estimate the known concentrations of stable synthetic A1 adenosine receptor agonists in isolated, paced guinea pig left atria. The estimates were then compared to the known agonist concentrations (to assess the accuracy of RRM); furthermore, the 95% confidence limits of the best-fit values were also considered (to evaluate the precision of RRM). It was found that, although the global fitting offered the most convenient way to perform RRM, the best estimates were provided by the individual fitting without any weighting, almost irrespective of the fact whether ordinary or robust fitting was chosen.
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Adenosine Receptor Profiling Reveals an Association between the Presence of Spare Receptors and Cardiovascular Disorders. Int J Mol Sci 2019; 20:ijms20235964. [PMID: 31783510 PMCID: PMC6928742 DOI: 10.3390/ijms20235964] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 11/19/2019] [Accepted: 11/21/2019] [Indexed: 02/06/2023] Open
Abstract
Adenosine and its receptors exert a potent control on the cardiovascular system. This review aims to present emerging experimental evidence supporting the existence and implication in cardiovascular disorders of specific adenosinergic pharmacological profiles, conforming to the concept of "receptor reserve", also known as "spare receptors". This kind of receptors allow agonists to achieve their maximal effect without occupying all of the relevant cell receptors. In the cardiovascular system, spare adenosine receptors appear to compensate for a low extracellular adenosine level and/or a low adenosine receptor number, such as in coronary artery disease or some kinds of neurocardiogenic syncopes. In both cases, the presence of spare receptors appears to be an attempt to overcome a weak interaction between adenosine and its receptors. The identification of adenosine spare receptors in cardiovascular disorders may be helpful for diagnostic purposes.
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