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Fontana IC, Kumar A, Okamura N, Nordberg A. Multitracer Approach to Understanding the Complexity of Reactive Astrogliosis in Alzheimer's Brains. ACS Chem Neurosci 2024; 15:328-336. [PMID: 38133820 PMCID: PMC10797624 DOI: 10.1021/acschemneuro.3c00646] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
A monoamine oxidase B (MAO-B) selective positron emission tomography (PET) tracer [11C]-deuterium-l-deprenyl holds promise for imaging reactive astrogliosis in neurodegenerative diseases, such as Alzheimer's disease (AD). Two novel PET tracers ([11C]-BU99008 and [18F]-SMBT-1) have recently been developed to assess the complexity of reactive astrogliosis in the AD continuum. We have investigated the binding properties of SMBT-1, l-deprenyl, and BU99008 in AD and cognitively normal control (CN) brains. Competition binding assays with [3H]-l-deprenyl and [3H]-BU99008 versus unlabeled SMBT-1 in postmortem AD and CN temporal and frontal cortex brains demonstrated that SMBT-1 interacted with [3H]-deprenyl at a single binding site (nM range) and with [3H]-BU99008 at multiple binding sites (from nM to μM). Autoradiography studies on large frozen postmortem AD and CN hemisphere brain sections demonstrated that 1 μM SMBT-1 almost completely displaced the [3H]-l-deprenyl binding (>90%), while SMBT-1 only partly displaced the [3H]-BU99008 binding (50-60% displacement) in cortical regions. In conclusion, SMBT-1, l-deprenyl, and BU99008 interact at the same MAO-B binding site, while BU99008 shows an additional independent binding site in AD and CN brains. The high translational power of our studies in human AD and CN brains suggests that the multitracer approach with SMBT-1, l-deprenyl, and BU99008 could be useful for imaging reactive astrogliosis.
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Affiliation(s)
- Igor C. Fontana
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
| | - Amit Kumar
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
| | - Nobuyuki Okamura
- Department
of Pharmacology, Tohoku Medical and Pharmaceutical
University, Sendai 983-8536, Japan
| | - Agneta Nordberg
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
- Theme
Inflammation and Aging, Karolinska University
Hospital, S-141 57 Stockholm, Sweden
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2
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Fontana IC, Scarpa M, Malarte ML, Rocha FM, Ausellé-Bosch S, Bluma M, Bucci M, Chiotis K, Kumar A, Nordberg A. Astrocyte Signature in Alzheimer's Disease Continuum through a Multi-PET Tracer Imaging Perspective. Cells 2023; 12:1469. [PMID: 37296589 PMCID: PMC10253101 DOI: 10.3390/cells12111469] [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: 02/01/2023] [Revised: 05/02/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023] Open
Abstract
Reactive astrogliosis is an early event in the continuum of Alzheimer's disease (AD). Current advances in positron emission tomography (PET) imaging provide ways of assessing reactive astrogliosis in the living brain. In this review, we revisit clinical PET imaging and in vitro findings using the multi-tracer approach, and point out that reactive astrogliosis precedes the deposition of Aβ plaques, tau pathology, and neurodegeneration in AD. Furthermore, considering the current view of reactive astrogliosis heterogeneity-more than one subtype of astrocyte involved-in AD, we discuss how astrocytic body fluid biomarkers might fit into trajectories different from that of astrocytic PET imaging. Future research focusing on the development of innovative astrocytic PET radiotracers and fluid biomarkers may provide further insights into the heterogeneity of reactive astrogliosis and improve the detection of AD in its early stages.
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Affiliation(s)
- Igor C. Fontana
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Miriam Scarpa
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Mona-Lisa Malarte
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Filipa M. Rocha
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Instituto de Ciência Biomédicas Abel Salazar da Universidade do Porto, 4050-313 Porto, Portugal
- Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal
| | - Sira Ausellé-Bosch
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Faculty of Health and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain
| | - Marina Bluma
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Marco Bucci
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Konstantinos Chiotis
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Amit Kumar
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Theme Inflammation and Aging, Karolinska University Hospital, 141 57 Stockholm, Sweden
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3
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Holt A. Conventional Receptor Radioligand Binding Techniques Applied to the Study of Monoamine Oxidase. Methods Mol Biol 2023; 2558:75-96. [PMID: 36169857 DOI: 10.1007/978-1-0716-2643-6_7] [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] [Indexed: 06/16/2023]
Abstract
Designed to measure binding interactions between small molecules and receptor proteins, radioligand binding approaches may also be applied to interactions between monoamine oxidase (MAO) and its ligands. The technique may be used with tissue homogenates or with mitochondrial membranes and can provide information about binding site density, ligand affinity, binding rate constants, and binding events at sites that do not impact absorbance characteristics of the flavin cofactor and that may not be amenable to spectrophotometric studies. This overview describes the use of a cell harvester in a common filtration approach to measure binding to MAO of radiolabeled substrates, inhibitors, or allosteric ligands in saturation analyses and to take advantage of the principles of competition to obtain quantitative binding data for unlabeled ligands that may bind with much lower affinity. The quality and reproducibility of data are impacted by factors such as choice of ligand concentrations, pipetting technique, graphing and regression approaches, and scintillation counting parameters, and consideration is given to these and other factors that may influence the results.
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Affiliation(s)
- Andrew Holt
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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4
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Behl T, Kaur D, Sehgal A, Singh S, Sharma N, Zengin G, Andronie-Cioara FL, Toma MM, Bungau S, Bumbu AG. Role of Monoamine Oxidase Activity in Alzheimer's Disease: An Insight into the Therapeutic Potential of Inhibitors. Molecules 2021; 26:molecules26123724. [PMID: 34207264 PMCID: PMC8234097 DOI: 10.3390/molecules26123724] [Citation(s) in RCA: 105] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 02/03/2023] Open
Abstract
Despite not being utilized as considerably as other antidepressants in the therapy of depression, the monoamine oxidase inhibitors (MAOIs) proceed to hold a place in neurodegeneration and to have a somewhat broad spectrum in respect of the treatment of neurological and psychiatric conditions. Preclinical and clinical studies on MAOIs have been developing in recent times, especially on account of rousing discoveries manifesting that these drugs possess neuroprotective activities. The altered brain levels of monoamine neurotransmitters due to monoamine oxidase (MAO) are directly associated with various neuropsychiatric conditions like Alzheimer’s disease (AD). Activated MAO induces the amyloid-beta (Aβ) deposition via abnormal cleavage of the amyloid precursor protein (APP). Additionally, activated MAO contributes to the generation of neurofibrillary tangles and cognitive impairment due to neuronal loss. No matter the attention of researchers on the participation of MAOIs in neuroprotection has been on monoamine oxidase-B (MAO-B) inhibitors, there is a developing frame of proof indicating that monoamine oxidase-A (MAO-A) inhibitors may also play a role in neuroprotection. The therapeutic potential of MAOIs alongside the complete understanding of the enzyme’s physiology may lead to the future advancement of these drugs.
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Affiliation(s)
- Tapan Behl
- Department of Pharmacology, Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India; (D.K.); (A.S.); (S.S.); (N.S.)
- Correspondence: (T.B.); (S.B.)
| | - Dapinder Kaur
- Department of Pharmacology, Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India; (D.K.); (A.S.); (S.S.); (N.S.)
| | - Aayush Sehgal
- Department of Pharmacology, Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India; (D.K.); (A.S.); (S.S.); (N.S.)
| | - Sukhbir Singh
- Department of Pharmacology, Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India; (D.K.); (A.S.); (S.S.); (N.S.)
| | - Neelam Sharma
- Department of Pharmacology, Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India; (D.K.); (A.S.); (S.S.); (N.S.)
| | - Gokhan Zengin
- Department of Biology, Faculty of Science, Selcuk University Campus, 42130 Konya, Turkey;
| | - Felicia Liana Andronie-Cioara
- Department of Psycho-Neuroscience and Recovery, Faculty of Medicine and Pharmacy, University of Oradea, 410073 Oradea, Romania;
| | - Mirela Marioara Toma
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, 410028 Oradea, Romania;
- Doctoral School of Biomedical Sciences, University of Oradea, 410073 Oradea, Romania
| | - Simona Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, 410028 Oradea, Romania;
- Doctoral School of Biomedical Sciences, University of Oradea, 410073 Oradea, Romania
- Correspondence: (T.B.); (S.B.)
| | - Adrian Gheorghe Bumbu
- Department of Surgical Disciplines, Faculty of Medicine and Pharmacy, University of Oradea, 410073 Oradea, Romania;
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5
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Tararina MA, Dam KK, Dhingra M, Janda KD, Palfey BA, Allen KN. Fast Kinetics Reveals Rate-Limiting Oxidation and the Role of the Aromatic Cage in the Mechanism of the Nicotine-Degrading Enzyme NicA2. Biochemistry 2021; 60:259-273. [PMID: 33464876 DOI: 10.1021/acs.biochem.0c00855] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In Pseudomonas putida, the flavoprotein nicotine oxidoreductase (NicA2) catalyzes the oxidation of (S)-nicotine to N-methyl-myosmine, which is nonenzymatically hydrolyzed to pseudooxynicotine. Structural analysis reveals a monoamine oxidase (MAO)-like fold with a conserved FAD-binding domain and variable substrate-binding domain. The flavoenzyme has a unique variation of the classic aromatic cage with flanking residue pair W427/N462. Previous mechanistic studies using O2 as the oxidizing substrate show that NicA2 has a low apparent Km of 114 nM for (S)-nicotine with a very low apparent turnover number (kcat of 0.006 s-1). Herein, the mechanism of NicA2 was analyzed by transient kinetics. Single-site variants of W427 and N462 were used to probe the roles of these residues. Although several variants had moderately higher oxidase activity (7-12-fold), their reductive half-reactions using (S)-nicotine were generally significantly slower than that of wild-type NicA2. Notably, the reductive half-reaction of wild-type NicA2 is 5 orders of magnitude faster than the oxidative half-reaction with an apparent pseudo-first-order rate constant for the reaction of oxygen similar to kcat. X-ray crystal structures of the N462V and N462Y/W427Y variants complexed with (S)-nicotine (at 2.7 and 2.3 Å resolution, respectively) revealed no significant active-site rearrangements. A second substrate-binding site was identified in N462Y/W427Y, consistent with observed substrate inhibition. Together, these findings elucidate the mechanism of a flavoenzyme that preferentially oxidizes tertiary amines with an efficient reductive half-reaction and a very slow oxidative half-reaction when O2 is the oxidizing substrate, suggesting that the true oxidizing agent is unknown.
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Affiliation(s)
- Margarita A Tararina
- Program in Biomolecular Pharmacology, Boston University School of Medicine, 72 East Concord Street, Boston, Massachusetts 02118, United States
| | - Katie K Dam
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Manaswni Dhingra
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | | | - Bruce A Palfey
- Department of Biological Chemistry, University of Michigan, 5220E MSRB III 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, United States
| | - Karen N Allen
- Program in Biomolecular Pharmacology, Boston University School of Medicine, 72 East Concord Street, Boston, Massachusetts 02118, United States.,Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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Astroglial tracer BU99008 detects multiple binding sites in Alzheimer's disease brain. Mol Psychiatry 2021; 26:5833-5847. [PMID: 33888872 PMCID: PMC8758481 DOI: 10.1038/s41380-021-01101-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/17/2021] [Accepted: 04/01/2021] [Indexed: 12/15/2022]
Abstract
With reactive astrogliosis being established as one of the hallmarks of Alzheimer's disease (AD), there is high interest in developing novel positron emission tomography (PET) tracers to detect early astrocyte reactivity. BU99008, a novel astrocytic PET ligand targeting imidazoline-2 binding sites (I2BS) on astrocytes, might be a suitable candidate. Here we demonstrate for the first time that BU99008 could visualise reactive astrogliosis in postmortem AD brains and propose a multiple binding site [Super-high-affinity (SH), High-affinity (HA) and Low-affinity (LA)] model for BU99008, I2BS specific ligands (2-BFI and BU224) and deprenyl in AD and control (CN) brains. The proportion (%) and affinities of these sites varied significantly between the BU99008, 2-BFI, BU224 and deprenyl in AD and CN brains. Regional binding studies demonstrated significantly higher 3H-BU99008 binding in AD brain regions compared to CN. Comparative autoradiography studies reinforced these findings, showing higher specific binding for 3H-BU99008 than 3H-Deprenyl in sporadic AD brain compared to CN, implying that they might have different targets. The data clearly shows that BU99008 could detect I2BS expressing reactive astrocytes with good selectivity and specificity and hence be a potential attractive clinical astrocytic PET tracer for gaining further insight into the role of reactive astrogliosis in AD.
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7
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Vasilopoulou F, Griñán-Ferré C, Rodríguez-Arévalo S, Bagán A, Abás S, Escolano C, Pallàs M. I 2 imidazoline receptor modulation protects aged SAMP8 mice against cognitive decline by suppressing the calcineurin pathway. GeroScience 2020; 43:965-983. [PMID: 33128688 PMCID: PMC8110656 DOI: 10.1007/s11357-020-00281-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 09/28/2020] [Indexed: 12/26/2022] Open
Abstract
Brain aging and dementia are current problems that must be solved. The levels of imidazoline 2 receptors (I2-IRs) are increased in the brain in Alzheimer's disease (AD) and other neurodegenerative diseases. We tested the action of the specific and selective I2-IR ligand B06 in a mouse model of accelerated aging and AD, the senescence-accelerated mouse prone 8 (SAMP8) model. Oral administration of B06 for 4 weeks improved SAMP8 mouse behavior and cognition and reduced AD hallmarks, oxidative stress, and apoptotic and neuroinflammation markers. Likewise, B06 regulated glial excitatory amino acid transporter 2 and N-methyl-D aspartate 2A and 2B receptor subunit protein levels. Calcineurin (CaN) is a phosphatase that controls the phosphorylation levels of cAMP response element-binding (CREB), apoptotic mediator BCL-2-associated agonist of cell death (BAD) and GSK3β, among other molecules. Interestingly, B06 was able to reduce the levels of the CaN active form (CaN A). Likewise, CREB phosphorylation, BAD gene expression, and other factors were modified after B06 treatment. Moreover, phosphorylation of a target of CaN, nuclear factor of activated T-cells, cytoplasmic 1 (NFATC1), was increased in B06-treated mice, impeding the transcription of genes related to neuroinflammation and neural plasticity. In summary, this I2 imidazoline ligand can exert its beneficial effects on age-related conditions by modulating CaN pathway action and affecting several molecular pathways, playing a neuroprotective role in SAMP8 mice.
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Affiliation(s)
- Foteini Vasilopoulou
- Pharmacology Section, Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Neurociencies, University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain
| | - Christian Griñán-Ferré
- Pharmacology Section, Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Neurociencies, University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain
| | - Sergio Rodríguez-Arévalo
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain
| | - Andrea Bagán
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain
| | - Sònia Abás
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain
| | - Carmen Escolano
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain
| | - Mercè Pallàs
- Pharmacology Section, Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Neurociencies, University of Barcelona, Av. Joan XXIII, 27-31, E-08028, Barcelona, Spain.
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Manzoor S, Hoda N. A comprehensive review of monoamine oxidase inhibitors as Anti-Alzheimer's disease agents: A review. Eur J Med Chem 2020; 206:112787. [PMID: 32942081 DOI: 10.1016/j.ejmech.2020.112787] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 07/22/2020] [Accepted: 08/25/2020] [Indexed: 02/07/2023]
Abstract
Monoamine oxidases (MAO-A and MAO-B) are mammalian flavoenzyme, which catalyze the oxidative deamination of several neurotransmitters like norepinephrine, dopamine, tyramine, serotonin, and some other amines. The oxidative deamination produces several harmful side products like ammonia, peroxides, and aldehydes during the biochemical reaction. The concentration of biochemical neurotransmitter alteration in the brain by MAO is directly related with several neurological disorders like Alzheimer's disease and Parkinson's disease (PD). Activated MAO also contributes to the amyloid beta (Aβ) aggregation by two successive cleft β-secretase and γ-secretase of amyloid precursor protein (APP). Additionally, activated MAO is also involved in aggregation of neurofibrillary tangles and cognitive destruction through the cholinergic neuronal damage and disorder of the cholinergic system. MAO inhibition has general anti-Alzheimer's disease effect as a consequence of oxidative stress reduction prompted by MAO enzymes. In this review, we outlined and addressed recent understanding on MAO enzymes such as their structure, physiological function, catalytic mechanism, and possible therapeutic goals in AD. In addition, it also highlights the current development and discovery of potential MAO inhibitors (MAOIs) from various chemical scaffolds.
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Affiliation(s)
- Shoaib Manzoor
- Drug Design and Synthesis Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025, India
| | - Nasimul Hoda
- Drug Design and Synthesis Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025, India.
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9
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Dasgupta S, Mukherjee S, Sekar K, Mukhopadhyay BP. The conformational dynamics of wing gates Ile199 and Phe103 on the binding of dopamine and benzylamine substrates in human monoamine Oxidase B. J Biomol Struct Dyn 2020; 39:1879-1886. [PMID: 32093545 DOI: 10.1080/07391102.2020.1734483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Subrata Dasgupta
- Department of Chemistry, National Institute of Technology-Durgapur, West Bengal, Durgapur, India
| | - Soumita Mukherjee
- Department of Chemistry, National Institute of Technology-Durgapur, West Bengal, Durgapur, India
| | - Kanakaraj Sekar
- Laboratory for Structural Biology and Bio-Computing, Department of Computational and Data Sciences, Indian Institute of Science Bangalore, India
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10
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Vellani V, Sabatini C, Milia C, Caselli G, Lanza M, Letari O, Rovati LC, Giacomoni C. CR4056, a powerful analgesic imidazoline-2 receptor ligand, inhibits the inflammation-induced PKCε phosphorylation and membrane translocation in sensory neurons. Br J Pharmacol 2019; 177:48-64. [PMID: 31454418 DOI: 10.1111/bph.14845] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE CR4056 is a first-in-class imidazoline-2 (I2 ) receptor ligand characterized by potent analgesic activity in different experimental animal models of pain. In a recent phase II clinical trial, CR4056 effectively reduced pain in patients with knee osteoarthritis. In the present study, we investigated the effects of CR4056 on PKCε translocation in vitro and on PKCε activation in vivo in dorsal root ganglia (DRG) neurons. EXPERIMENTAL APPROACH Effects of CR4056 on bradykinin-induced PKCε translocation were studied in rat sensory neurons by immunocytochemistry. PKCε activation was investigated by immunohistochemistry analysis of DRG from complete Freund's adjuvant-treated animals developing local hyperalgesia. The analgesic activity of CR4056 was tested on the same animals. KEY RESULTS CR4056 inhibited PKCε translocation with very rapid and long-lasting activity. CR4056 decreased hyperalgesia and phospho-PKCε immunoreactivity in the DRG neurons innervating the inflamed paw. The effect of CR4056 on PKCε translocation was blocked by pertussis toxin, implying that the intracellular pathways involved Gi proteins. The inhibition of PKCε translocation by CR4056 was independent of the α2 -adrenoeceptor and, surprisingly, was also independent of idazoxan-sensitive I2 binding sites. The I2 agonist 2BFI had no effect alone but potentiated the activity of low concentrations of CR4056. CONCLUSIONS AND IMPLICATIONS Our results demonstrate that CR4056 shares the ability to inhibit PKCε translocation with other analgesics. Whether the inhibition of PKCε involves binding to specific subtype(s) of I2 receptors should be further investigated. If so, this would be a new mode of action of a highly specific I2 receptor ligand.
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Affiliation(s)
- Vittorio Vellani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Università di Modena e Reggio Emilia, Modena, Italy
| | - Chiara Sabatini
- Rottapharm Biotech, Monza, Italy.,PhD Program in Neuroscience, Dipartimento di Medicina e chirurgia, Università degli Studi di Milano-Bicocca, Monza, Italy
| | - Chiara Milia
- PhD Program in Neuroscience, Dipartimento di Medicina e chirurgia, Università degli Studi di Milano-Bicocca, Monza, Italy
| | | | | | | | | | - Chiara Giacomoni
- Dipartimento di Economia, Scienze e Diritto, Università degli Studi della Repubblica di San Marino, San Marino
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11
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Wilson H, Dervenoulas G, Pagano G, Tyacke RJ, Polychronis S, Myers J, Gunn RN, Rabiner EA, Nutt D, Politis M. Imidazoline 2 binding sites reflecting astroglia pathology in Parkinson's disease: an in vivo11C-BU99008 PET study. Brain 2019; 142:3116-3128. [PMID: 31504212 DOI: 10.1093/brain/awz260] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/06/2019] [Accepted: 07/04/2019] [Indexed: 12/11/2022] Open
Abstract
Astroglia are multifunctional cells that regulate neuroinflammation and maintain homeostasis within the brain. Astroglial α-synuclein-positive cytoplasmic accumulations have been shown post-mortem in patients with Parkinson's disease and therefore astroglia may play an important role in the initiation and progression of Parkinson's disease. Imidazoline 2 binding sites are expressed on activated astroglia in the cortex, hippocampus, basal ganglia and brainstem; therefore, by measuring imidazoline 2 binding site levels we can indirectly evaluate astrogliosis in patients with Parkinson's disease. Here, we aimed to evaluate the role of astroglia activation in vivo in patients with Parkinson's disease using 11C-BU99008 PET, a novel radioligand with high specificity and selectivity for imidazoline 2 binding sites. Twenty-two patients with Parkinson's disease and 14 healthy control subjects underwent 3 T MRI and a 120-min 11C-BU99008 PET scan with volume of distribution (VT) estimated using a two-tissue compartmental model with a metabolite corrected arterial plasma input function. Parkinson's disease patients were stratified into early (n = 8) and moderate/advanced (n = 14) groups according to disease stage. In early Parkinson's disease, increased 11C-BU99008 VT uptake was observed in frontal (P = 0.022), temporal (P = 0.02), parietal (P = 0.026) and occipital (P = 0.047) cortical regions compared with healthy controls. The greatest 11C-BU99008 VT increase in patients with early Parkinson's disease was observed in the brainstem (52%; P = 0.018). In patients with moderate/advanced Parkinson's disease, loss of 11C-BU99008 VT was observed across frontal (P = 0.002), temporal (P < 0.001), parietal (P = 0.039), occipital (P = 0.024), and insula (P < 0.001) cortices; and in the subcortical regions of caudate (P < 0.001), putamen (P < 0.001) and thalamus (P < 0.001); and in the brainstem (P = 0.018) compared with healthy controls. In patients with Parkinson's disease, loss of 11C-BU99008 VT in cortical regions, striatum, thalamus and brainstem correlated with longer disease duration (P < 0.05) and higher disease burden scores, measured with Movement Disorder Society Unified Parkinson's Disease Rating Scale (P < 0.05). In the subgroup of patients with moderate/advanced Parkinson's disease, loss of 11C-BU99008 VT in the frontal (r = 0.79; P = 0.001), temporal (r = 0.74; P = 0.002) and parietal (r = 0.89; P < 0.001) cortex correlated with global cognitive impairment. This study demonstrates in vivo the role of astroglia in the initiation and progression of Parkinson's disease. Reactive astroglia observed early in Parkinson's disease could reflect a neuroprotective compensatory mechanisms and pro-inflammatory upregulation in response to α-synuclein accumulation. However, as the disease progresses and significant neurodegeneration occurs, astroglia lose their reactive function and such loss in the cortex has clinical relevance in the development of cognitive impairment.
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Affiliation(s)
- Heather Wilson
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - George Dervenoulas
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Gennaro Pagano
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Robin J Tyacke
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, UK
| | - Sotirios Polychronis
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Jim Myers
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, UK
| | - Roger N Gunn
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
- Invicro LLC, Centre for Imaging Sciences, Hammersmith Hospital, London, UK
| | - Eugenii A Rabiner
- Invicro LLC, Centre for Imaging Sciences, Hammersmith Hospital, London, UK
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - David Nutt
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, UK
| | - Marios Politis
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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12
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Siemian JN, Shang L, Seaman RW, Zhu Q, Zhang Y, Li JX. Effects of imidazoline I2 receptor agonists on reserpine-induced hyperalgesia and depressive-like behavior in rats. Behav Pharmacol 2019; 30:429-434. [PMID: 30383551 PMCID: PMC6494737 DOI: 10.1097/fbp.0000000000000454] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pharmacotherapies for fibromyalgia treatment are lacking. This study examined the antinociceptive and antidepressant-like effects of imidazoline I2 receptor (I2R) agonists in a reserpine-induced model of fibromyalgia in rats. Rats were treated for 3 days with vehicle or reserpine. The von Frey filament test was used to assess the antinociceptive effects of I2 receptor agonists, and the forced swim test was used to assess the antidepressant-like effects of these drugs. 2-BFI (3.2-10 mg/kg, intraperitoneally), phenyzoline (17.8-56 mg/kg, intraperitoneally), and CR4056 (3.2-10 mg/kg, intraperitoneally) all dose-dependently produced significant antinociceptive effects, which were attenuated by the I2R antagonist idazoxan. Only CR4056 significantly reduced the immobility time in the forced swim test in both vehicle-treated and reserpine-treated rats. These data suggest that I2R agonists may be useful to treat fibromyalgia-related pain and comorbid depression.
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Affiliation(s)
- Justin N. Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Li Shang
- Department of Nursing, Affiliated Yantai Hospital of Binzhou Medical University, Yantai, Shandong, China
| | - Robert W. Seaman
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Qing Zhu
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
- School of Pharmacy, Nantong University, Nantong, Jiangsu, China
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, North Carolina, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
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13
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Griñán-Ferré C, Vasilopoulou F, Abás S, Rodríguez-Arévalo S, Bagán A, Sureda FX, Pérez B, Callado LF, García-Sevilla JA, García-Fuster MJ, Escolano C, Pallàs M. Behavioral and Cognitive Improvement Induced by Novel Imidazoline I 2 Receptor Ligands in Female SAMP8 Mice. Neurotherapeutics 2019; 16:416-431. [PMID: 30460457 PMCID: PMC6554384 DOI: 10.1007/s13311-018-00681-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
As populations increase their life expectancy, age-related neurodegenerative disorders such as Alzheimer's disease have become more common. I2-Imidazoline receptors (I2-IR) are widely distributed in the central nervous system, and dysregulation of I2-IR in patients with neurodegenerative diseases has been reported, suggesting their implication in cognitive impairment. This evidence indicates that high-affinity selective I2-IR ligands potentially contribute to the delay of neurodegeneration. In vivo studies in the female senescence accelerated mouse-prone 8 mice have shown that treatment with I2-IR ligands, MCR5 and MCR9, produce beneficial effects in behavior and cognition. Changes in molecular pathways implicated in oxidative stress, inflammation, synaptic plasticity, and apoptotic cell death were also studied. Furthermore, treatments with these I2-IR ligands diminished the amyloid precursor protein processing pathway and increased Aβ degrading enzymes in the hippocampus of SAMP8 mice. These results collectively demonstrate the neuroprotective role of these new I2-IR ligands in a mouse model of brain aging through specific pathways and suggest their potential as therapeutic agents in brain disorders and age-related neurodegenerative diseases.
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Affiliation(s)
- Christian Griñán-Ferré
- Pharmacology Section, Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institut de Neurociències, University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
| | - Foteini Vasilopoulou
- Pharmacology Section, Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institut de Neurociències, University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
| | - Sònia Abás
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
| | - Sergio Rodríguez-Arévalo
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
| | - Andrea Bagán
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
| | - Francesc X Sureda
- Pharmacology Unit, Faculty of Medicine and Health Sciences, University of Rovira and Virgili, C./St. Llorenç 21, 43201, Reus, Tarragona, Spain
| | - Belén Pérez
- Departament of Pharmacology, Therapeutic and Toxicology, Autonomous University of Barcelona, 08193, Barcelona, Spain
| | - Luis F Callado
- Department of Pharmacology, University of the Basque Country, UPV/EHU, 48940, Leioa, Bizkaia, Spain
- Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Leioa, Spain
| | - Jesús A García-Sevilla
- Laboratory of Neuropharmacology, IUNICS and IdISBa, University of the Balearic Islands (UIB), Cra. Valldemossa km 7.5, 07122, Palma de Mallorca, Spain
| | - M Julia García-Fuster
- Laboratory of Neuropharmacology, IUNICS and IdISBa, University of the Balearic Islands (UIB), Cra. Valldemossa km 7.5, 07122, Palma de Mallorca, Spain
| | - Carmen Escolano
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
| | - Mercè Pallàs
- Pharmacology Section, Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institut de Neurociències, University of Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain.
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14
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Tripathi RKP, Ayyannan SR. Monoamine oxidase-B inhibitors as potential neurotherapeutic agents: An overview and update. Med Res Rev 2019; 39:1603-1706. [PMID: 30604512 DOI: 10.1002/med.21561] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 12/13/2018] [Accepted: 12/15/2018] [Indexed: 12/23/2022]
Abstract
Monoamine oxidase (MAO) inhibitors have made significant contributions and remain an indispensable approach of molecular and mechanistic diversity for the discovery of antineurodegenerative drugs. However, their usage has been hampered by nonselective and/or irreversible action which resulted in drawbacks like liver toxicity, cheese effect, and so forth. Hence, the search for selective MAO inhibitors (MAOIs) has become a substantial focus in current drug discovery. This review summarizes our current understanding on MAO-A/MAO-B including their structure, catalytic mechanism, and biological functions with emphases on the role of MAO-B as a potential therapeutic target for the development of medications treating neurodegenerative disorders. It also highlights the recent developments in the discovery of potential MAO-B inhibitors (MAO-BIs) belonging to diverse chemical scaffolds, arising from intensive chemical-mechanistic and computational studies documented during past 3 years (2015-2018), with emphases on their potency and selectivity. Importantly, readers will gain knowledge of various newly established MAO-BI scaffolds and their development potentials. The comprehensive information provided herein will hopefully accelerate ideas for designing novel selective MAO-BIs with superior activity profiles and critical discussions will inflict more caution in the decision-making process in the MAOIs discovery.
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Affiliation(s)
- Rati Kailash Prasad Tripathi
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi, India.,Department of Pharmaceutical Chemistry, Parul Institute of Pharmacy, Parul University, Vadodara, India
| | - Senthil Raja Ayyannan
- Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi, India
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15
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On the practical aspects of characterising monoamine oxidase inhibition in vitro. J Neural Transm (Vienna) 2018; 125:1685-1705. [PMID: 30374594 DOI: 10.1007/s00702-018-1943-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 10/13/2018] [Indexed: 10/28/2022]
Abstract
The development of novel inhibitors of human monoamine oxidase enzymes with improved pharmacodynamic and pharmacokinetic profiles has, in the past, been hampered by limited access to enzyme, by assay protocols offering limited throughput, and by inappropriate analyses of kinetic data. More recently, high-level expression of human enzymes in yeast has facilitated thorough examinations of steady-state enzyme behaviour that have led to improvements in our understanding of the mathematical underpinnings of kinetic analyses of monoamine oxidases. However, with these improvements have come a realisation that to be useful, more data points across wider concentration ranges are required. In turn, many discontinuous assay approaches, such as those involving radiolabelled substrates or chromatographic separation of product from substrate, have been rendered somewhat obsolete. Justification for the use of a platereader-based approach to assess the effects of novel inhibitors on monamine oxidases is provided, along with details of experimental design optimised to address the unexpectedly complex kinetics followed by these enzymes. Potential sources of error are discussed, and comments provided on techniques that may enhance the quality of experimental data.
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16
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Núñez-Vivanco G, Fierro A, Moya P, Iturriaga-Vásquez P, Reyes-Parada M. 3D similarities between the binding sites of monoaminergic target proteins. PLoS One 2018; 13:e0200637. [PMID: 30028869 PMCID: PMC6054423 DOI: 10.1371/journal.pone.0200637] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 06/30/2018] [Indexed: 02/06/2023] Open
Abstract
The study of binding site similarities can be relevant to understand the interaction of different drugs at several molecular targets. The increasing availability of protein crystal structures and the development of novel algorithms designed to evaluate three-dimensional similarities, represent a great opportunity to explore the existence of electronic and shape features shared by clinically relevant proteins, which could assist drug design and discovery. Proteins involved in the recognition of monoaminergic neurotransmitters, such as monoamine transporters or monoamine oxidases (MAO) have been related to several psychiatric and neurological disorders such as depression or Parkinson’s disease. In this work, we evaluated the possible existence of similarities among the binding sites of the serotonin transporter (SERT), the dopamine transporter (DAT), MAO-A and MAO-B. This study was carried out using molecular simulation methodologies linked to the statistical algorithm PocketMatch, which was modified in order to obtain similarities profiles. Our results show that DAT and SERT exhibit a high degree of 3-D similarities all along the pathway that is presumably involved in the substrate transport process. Distinct differences, on the other hand, were found both at the extracellular and the intracellular ends of the transporters, which might be involved in the selective initial recognition of the corresponding substrate. Similarities were also found between the active (catalytic) site of MAO-A and the extracellular vestibule of SERT (the S2 binding site). These results suggest some degree of structural convergence for these proteins, which have different functions, tissue distribution and genetic origin, but which share the same endogenous ligand (serotonin). Beyond the functional implications, these findings are valuable for the design of both selective and non-selective ligands.
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Affiliation(s)
- Gabriel Núñez-Vivanco
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile.,Escuela de Ingeniería Civil en Bioinformática, Universidad de Talca, Talca, Chile
| | | | - Pablo Moya
- Instituto de Fisiología, Universidad de Valparaíso, Valparaíso, Chile.,Centro Interdisciplinario de Neurociencia de Valparaíso CINV, Universidad de Valparaíso, Valparaíso, Chile
| | | | - Miguel Reyes-Parada
- School of Medicine, Faculty of Medical Sciences, University of Santiago de Chile, Santiago, Chile.,Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
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17
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Siemian JN, Wang K, Zhang Y, Li JX. Mechanisms of imidazoline I 2 receptor agonist-induced antinociception in rats: involvement of monoaminergic neurotransmission. Br J Pharmacol 2018; 175:1519-1534. [PMID: 29451703 DOI: 10.1111/bph.14161] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 12/17/2017] [Accepted: 02/04/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Although the antinociceptive efficacies of imidazoline I2 receptor agonists have been established, the exact post-receptor mechanisms remain unknown. This study tested the hypothesis that monoaminergic transmission is critical for I2 receptor agonist-induced antinociception. EXPERIMENTAL APPROACH von Frey filaments were used to assess antinociceptive effects of two I2 receptor agonists, 2-BFI and CR4056 on chronic constriction injury (CCI)-induced neuropathic pain or complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. Rectal temperature was measured to assess hypothermic effects of 2-BFI. A two-lever drug discrimination paradigm in which rats were trained to discriminate 5.6 mg·kg-1 2-BFI (i.p.) from its vehicle was used to examine the discriminative stimulus effects of 2-BFI. In each experiment, pharmacological mechanisms were investigated by combining 2-BFI or CR4056 with various pharmacological manipulations of the monoaminergic system including selective reuptake inhibition, monoamine depletion and monoamine receptor antagonism. KEY RESULTS In the CCI model, selective reuptake inhibitors of 5-HT (fluoxetine) or noradrenaline (desipramine), but not dopamine (GBR12909), enhanced 2-BFI-induced antinociception. Selective depletion of 5-HT or noradrenaline almost abolished 2-BFI-induced antinociception. 5-HT1A , 5-HT2A and α1 -adrenoceptor antagonists, but not other monoaminergic antagonists, attenuated 2-BFI and CR4056-induced antinociception in CCI and/or CFA models. However, none of these monoamine receptor antagonists significantly altered 2-BFI-induced hypothermia or discriminative stimulus effects. CONCLUSIONS AND IMPLICATIONS Antinociception induced by I2 receptor agonists was mediated by serotonergic and noradrenergic mechanisms with 5-HT1A , 5-HT2A and α1 -adrenoceptor being particularly important. In contrast, the hypothermic and discriminative stimulus effects of I2 receptor agonists were mediated by distinct, independent mechanisms.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
| | - Kaixuan Wang
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA.,School of Pharmacy, Yantai University, Yantai, Shandong Province, China
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18
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Siemian JN, Jia S, Liu JF, Zhang Y, Li JX. Neuroanatomical characterization of imidazoline I 2 receptor agonist-induced antinociception. Eur J Neurosci 2018. [PMID: 29514408 DOI: 10.1111/ejn.13899] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chronic pain is a significant public health problem with a lack of safe and effective analgesics. The imidazoline I2 receptor (I2 R) is a promising analgesic target, but the neuroanatomical structures involved in mediating I2 R-associated behaviors are unknown. I2 Rs are enriched in the arcuate nucleus, dorsal raphe (DR), interpeduncular nucleus, lateral mammillary body, medial habenula, nucleus accumbens (NAc) and paraventricular nucleus; thus, this study investigated the antinociceptive and hypothermic effects of microinjections of the I2 R agonist 2-(2-benzofuranyl)-2-imidazoline hydrochloride (2-BFI). In rats, intra-DR microinjections produced antinociception in complete Freund's adjuvant- and chronic constriction injury-induced pain models. Intra-NAc microinjections produced antinociception and increased noxious stimulus-associated side time in a place escape/avoidance paradigm. Intra-NAc pretreatment with the I2 R antagonist idazoxan but not the D1 receptor antagonist SCH23390 or the D2 receptor antagonist raclopride attenuated intra-NAc 2-BFI-induced antinociception. Intra-NAc idazoxan did not attenuate systemically administered 2-BFI-induced antinociception. Microinjections into the other regions did not produce antinociception, and in none of the regions produced hypothermia. These data suggest that I2 R activation in some but not all I2 R-enriched brain regions is sufficient to produce antinociception and supports the theory that different I2 R-associated effects are mediated via distinct receptor populations, which may in turn be distributed differentially throughout the CNS.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, 102 Farber Hall, 3435 Main St., Buffalo, NY, 14214, USA
| | - Shushan Jia
- Department of Anesthesiology, Yantai Affiliated Hospital, Binzhou Medical University, Yantai, China
| | - Jian-Feng Liu
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, 102 Farber Hall, 3435 Main St., Buffalo, NY, 14214, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, 102 Farber Hall, 3435 Main St., Buffalo, NY, 14214, USA
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19
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20
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Siemian JN, LaMacchia ZM, Spreuer V, Tian J, Ignatowski TA, Paez PM, Zhang Y, Li JX. The imidazoline I 2 receptor agonist 2-BFI attenuates hypersensitivity and spinal neuroinflammation in a rat model of neuropathic pain. Biochem Pharmacol 2018; 153:260-268. [PMID: 29366977 DOI: 10.1016/j.bcp.2018.01.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 01/18/2018] [Indexed: 11/25/2022]
Abstract
Chronic pain is a large, unmet public health problem. Recent studies have demonstrated the importance of neuroinflammation in the establishment and maintenance of chronic pain. However, pharmacotherapies that reduce neuroinflammation have not been successfully developed to treat chronic pain thus far. Several preclinical studies have established imidazoline I2 receptor (I2R) agonists as novel candidates for chronic pain therapies, and while some I2R ligands appear to modulate neuroinflammation in certain scenarios, whether they exert anti-neuroinflammatory effects in models of chronic pain is unknown. This study examined the effects of the prototypical I2R agonist 2-(2-benzofuranyl)-2-imidazoline hydrochloride (2-BFI) on hypersensitivity and neuroinflammation induced by chronic constriction injury (CCI), a neuropathic pain model in rats. In CCI rats, twice-daily treatment with 10 mg/kg 2-BFI for seven days consistently increased mechanical and thermal nociception thresholds, reduced GFAP and Iba-1 levels in the dorsal horn of the spinal cord, and reduced levels of TNF-α relative to saline treatment. These results were recapitulated in primary mouse cortical astrocyte cultures. Incubation with 2-BFI attenuated GFAP expression and supernatant TNF-α levels in LPS-stimulated cultures. These results suggest that I2R agonists such as 2-BFI may reduce neuroinflammation which may partially account for their antinociceptive effects.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA
| | - Zach M LaMacchia
- Department of Pathology and Anatomical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA
| | - Vilma Spreuer
- Hunter James Kelly Research Institute, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA
| | - Jingwei Tian
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA; School of Pharmacy, Yantai University, Yantai, Shandong, China
| | - Tracey A Ignatowski
- Department of Pathology and Anatomical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA
| | - Pablo M Paez
- Hunter James Kelly Research Institute, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, USA.
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21
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Oanca G, Stare J, Mavri J. How fast monoamine oxidases decompose adrenaline? Kinetics of isoenzymes A and B evaluated by empirical valence bond simulation. Proteins 2017; 85:2170-2178. [PMID: 28836294 DOI: 10.1002/prot.25374] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/18/2017] [Accepted: 08/21/2017] [Indexed: 12/22/2022]
Abstract
This work scrutinizes kinetics of decomposition of adrenaline catalyzed by monoamine oxidase (MAO) A and B enzymes, a process controlling the levels of adrenaline in the central nervous system and other tissues. Experimental kinetic data for MAO A and B catalyzed decomposition of adrenaline are reported only in the form of the maximum reaction rate. Therefore, we estimated the experimental free energy barriers form the kinetic data of closely related systems using regression method, as was done in our previous study. By using multiscale simulation on the Empirical Valence Bond (EVB) level, we studied the chemical reactivity of the MAO A catalyzed decomposition of adrenaline and we obtained a value of activation free energy of 17.3 ± 0.4 kcal/mol. The corresponding value for MAO B is 15.7 ± 0.7 kcal/mol. Both values are in good agreement with the estimated experimental barriers of 16.6 and 16.0 kcal/mol for MAO A and MAO B, respectively. The fact that we reproduced the kinetic data and preferential catalytic effect of MAO B over MAO A gives additional support to the validity of the proposed hydride transfer mechanism. Furthermore, we demonstrate that adrenaline is preferably involved in the reaction in a neutral rather than in a protonated form due to considerably higher barriers computed for the protonated adrenaline substrate. The results are discussed in the context of chemical mechanism of MAO enzymes and possible applications of multiscale simulation to rationalize the effects of MAO activity on adrenaline level.
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Affiliation(s)
- Gabriel Oanca
- Department of Computational Biochemistry and Drug Design, National Institute of Chemistry, Ljubljana, Slovenia.,Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi, Romania
| | - Jernej Stare
- Department of Computational Biochemistry and Drug Design, National Institute of Chemistry, Ljubljana, Slovenia
| | - Janez Mavri
- Department of Computational Biochemistry and Drug Design, National Institute of Chemistry, Ljubljana, Slovenia
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Ramsay RR, Tipton KF. Assessment of Enzyme Inhibition: A Review with Examples from the Development of Monoamine Oxidase and Cholinesterase Inhibitory Drugs. Molecules 2017; 22:E1192. [PMID: 28714881 PMCID: PMC6152246 DOI: 10.3390/molecules22071192] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 07/10/2017] [Accepted: 07/11/2017] [Indexed: 11/16/2022] Open
Abstract
The actions of many drugs involve enzyme inhibition. This is exemplified by the inhibitors of monoamine oxidases (MAO) and the cholinsterases (ChE) that have been used for several pharmacological purposes. This review describes key principles and approaches for the reliable determination of enzyme activities and inhibition as well as some of the methods that are in current use for such studies with these two enzymes. Their applicability and potential pitfalls arising from their inappropriate use are discussed. Since inhibitor potency is frequently assessed in terms of the quantity necessary to give 50% inhibition (the IC50 value), the relationships between this and the mode of inhibition is also considered, in terms of the misleading information that it may provide. Incorporation of more than one functionality into the same molecule to give a multi-target-directed ligands (MTDLs) requires careful assessment to ensure that the specific target effects are not significantly altered and that the kinetic behavior remains as favourable with the MTDL as it does with the individual components. Such factors will be considered in terms of recently developed MTDLs that combine MAO and ChE inhibitory functions.
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Affiliation(s)
- Rona R Ramsay
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 8QP, UK.
| | - Keith F Tipton
- School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland.
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23
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Multiscale simulation of monoamine oxidase catalyzed decomposition of phenylethylamine analogs. Eur J Pharmacol 2017; 817:46-50. [PMID: 28583428 DOI: 10.1016/j.ejphar.2017.05.061] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/31/2017] [Accepted: 05/31/2017] [Indexed: 01/01/2023]
Abstract
Phenylethylamine (PEA) is an endogenous amphetamine and its levels are increased by physical activity. As other biogenic monoamines, it is decomposed by monoamine oxidase (MAO) enzymes. The chemical mechanism of MAO, and flavoenzymes in general, is a subject of heated debate. We have previously shown that the rate-limiting step of MAO catalysis involves a hydride transfer from the substrate methylene group vicinal to the amino group to the N5 atom of the lumiflavin co-factor moiety. By using multiscale simulation on the Empirical Valence Bond (EVB) level, we studied the chemical reactivity of the monoamine oxidase B catalyzed decomposition of PEA and its two derivatives: p-chloro-β-methylphenylamine (p-CMP) and p-methoxy-β-methylphenethylamine (p-MMP). We calculated activation free energies of 17.1kcal/mol (PEA), 18.4kcal/mol (p-MMP) and 20.0kcal/mol (p-CMP), which are in excellent agreement with the experimental values of 16.7kcal/mol for PEA and 18.3kcal/mol for p-MMP, while the experimental value for p-CMP is not available. This gives strong support to the validity of our hydride transfer mechanism for both MAO A and B isoforms. The results are discussed in the context of the interplay between MAO point mutations and neuropsychiatric disorders.
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24
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Tolerance and cross-tolerance to the antinociceptive effects of oxycodone and the imidazoline I 2 receptor agonist phenyzoline in adult male rats. Psychopharmacology (Berl) 2017; 234:1871-1880. [PMID: 28314949 PMCID: PMC5451304 DOI: 10.1007/s00213-017-4599-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 03/08/2017] [Indexed: 10/19/2022]
Abstract
RATIONALE Emerging evidence suggests the potential utility of combining opioids with imidazoline I2 receptor agonists for chronic pain. However, chronic pain management requires prolonged pharmacotherapy, and the consequence of such combination therapy remains unclear. OBJECTIVE This study examined the anti-hyperalgesic effect of the opioid oxycodone, the selective I2 receptor agonist phenyzoline, alone and in combination, during prolonged treatment. METHODS Von Frey filament test was used to examine the anti-hyperalgesic effect of drugs in complete Freund's adjuvant (CFA)-induced inflammatory pain or chronic constriction injury (CCI)-induced neuropathic pain in rats. Twice-daily treatment with oxycodone and phenyzoline, alone or in combination, was continued until the development of significant tolerance (oxycodone) or as long as 19 days passed (phenyzoline). RESULTS In rats receiving CFA or CCI manipulation, mechanical hyperalgesia was dose-dependently reversed by oxycodone and phenyzoline. Twice-daily treatment with 2 × ED50 dose of oxycodone for 7 days led to significant antinociceptive tolerance to oxycodone but not cross-tolerance to phenyzoline. Similarly, twice-daily treatment with 2 × ED50 dose of phenyzoline for 19 days led to significant antinociceptive tolerance to phenyzoline but not cross-tolerance to oxycodone. Twice-daily treatment with the combined oxycodone and phenyzoline using different ratios (1:3, 1:1 and 3: 1) at the doses that were functionally equivalent to the treatment doses of oxycodone and phenyzoline for 13-19 days generally led to delayed antinociceptive tolerance. CONCLUSIONS Combination therapy with oxycodone and I2 receptor agonists maintains prolonged antinociceptive effectiveness with reduced propensity to develop tolerance.
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25
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Abás S, Erdozain AM, Keller B, Rodríguez-Arévalo S, Callado LF, García-Sevilla JA, Escolano C. Neuroprotective Effects of a Structurally New Family of High Affinity Imidazoline I 2 Receptor Ligands. ACS Chem Neurosci 2017; 8:737-742. [PMID: 28029766 DOI: 10.1021/acschemneuro.6b00426] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The imidazoline I2 receptors (I2-IRs) are widely distributed in the brain, and I2-IR ligands may have therapeutic potential as neuroprotective agents. Since structural data for I2-IR remains unknown, the discovery of selective I2-IR ligands devoid of α2-adrenoceptor (α2-AR) affinity is likely to provide valuable tools in defining the pharmacological characterization of these receptors. We report the pharmacological characterization of a new family of (2-imidazolin-4-yl)phosphonates. Radioligand binding studies showed that they displayed a higher affinity for I2-IRs than idazoxan, and high I2/α2 selectivity. In vivo studies in mice showed that acute treatments with 1b and 2c significantly increased p-FADD/FADD ratio (an index of cell survival) in the hippocampus when compared with vehicle-treated controls. Additionally, acute and repeated treatments with 2c, but not with 1b, markedly reduced hippocampal p35 cleavage into neurotoxic p25. The present results indicate a neuroprotective potential of (2-imidazolin-4-yl)phosphonates acting at I2-IRs.
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Affiliation(s)
- Sònia Abás
- Laboratory
of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology,
Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences,
and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain
| | - Amaia M. Erdozain
- Department
of Pharmacology, University of the Basque Country, UPV/EHU, E-48940 Leioa, Bizkaia, Spain
- Centro
de Investigación Biomédica en Red de Salud Mental, CIBERSAM
| | - Benjamin Keller
- Laboratory
of Neuropharmacology, IUNICS/IdISPa, University of the Balearic Islands (UIB), Cra. Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Sergio Rodríguez-Arévalo
- Laboratory
of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology,
Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences,
and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain
| | - Luis F. Callado
- Department
of Pharmacology, University of the Basque Country, UPV/EHU, E-48940 Leioa, Bizkaia, Spain
- Centro
de Investigación Biomédica en Red de Salud Mental, CIBERSAM
| | - Jesús A. García-Sevilla
- Laboratory
of Neuropharmacology, IUNICS/IdISPa, University of the Balearic Islands (UIB), Cra. Valldemossa km 7.5, E-07122 Palma de Mallorca, Spain
| | - Carmen Escolano
- Laboratory
of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology,
Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences,
and Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII 27-31, E-08028 Barcelona, Spain
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26
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Marques SM, Daniel L, Buryska T, Prokop Z, Brezovsky J, Damborsky J. Enzyme Tunnels and Gates As Relevant Targets in Drug Design. Med Res Rev 2016; 37:1095-1139. [PMID: 27957758 DOI: 10.1002/med.21430] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/11/2016] [Accepted: 11/07/2016] [Indexed: 12/28/2022]
Abstract
Many enzymes contain tunnels and gates that are essential to their function. Gates reversibly switch between open and closed conformations and thereby control the traffic of small molecules-substrates, products, ions, and solvent molecules-into and out of the enzyme's structure via molecular tunnels. Many transient tunnels and gates undoubtedly remain to be identified, and their functional roles and utility as potential drug targets have received comparatively little attention. Here, we describe a set of general concepts relating to the structural properties, function, and classification of these interesting structural features. In addition, we highlight the potential of enzyme tunnels and gates as targets for the binding of small molecules. The different types of binding that are possible and the potential pharmacological benefits of such targeting are discussed. Twelve examples of ligands bound to the tunnels and/or gates of clinically relevant enzymes are used to illustrate the different binding modes and to explain some new strategies for drug design. Such strategies could potentially help to overcome some of the problems facing medicinal chemists and lead to the discovery of more effective drugs.
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Affiliation(s)
- Sergio M Marques
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Lukas Daniel
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Tomas Buryska
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Zbynek Prokop
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Jan Brezovsky
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
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27
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Poberžnik M, Purg M, Repič M, Mavri J, Vianello R. Empirical Valence Bond Simulations of the Hydride-Transfer Step in the Monoamine Oxidase A Catalyzed Metabolism of Noradrenaline. J Phys Chem B 2016; 120:11419-11427. [PMID: 27734680 DOI: 10.1021/acs.jpcb.6b09011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Monoamine oxidases (MAOs) A and B are flavoenzymes responsible for the metabolism of biogenic amines, such as dopamine, serotonin, and noradrenaline (NA), which is why they have been extensively implicated in the etiology and course of various neurodegenerative disorders and, accordingly, used as primary pharmacological targets to treat these debilitating cognitive diseases. The precise chemical mechanism through which MAOs regulate the amine concentration, which is vital for the development of novel inhibitors, is still not unambiguously determined in the literature. In this work, we present atomistic empirical valence bond simulations of the rate-limiting step of the MAO-A-catalyzed NA (norepinephrine) degradation, involving hydride transfer from the substrate α-methylene group to the flavin moiety of the flavin adenine dinucleotide prosthetic group, employing the full dimensionality and thermal fluctuations of the hydrated enzyme, with extensive configurational sampling. We show that MAO-A lowers the free energy of activation by 14.3 kcal mol-1 relative to that of the same reaction in aqueous solution, whereas the calculated activation free energy of ΔG‡ = 20.3 ± 1.6 kcal mol-1 is found to be in reasonable agreement with the correlated experimental value of 16.5 kcal mol-1. The results presented here strongly support the fact that both MAO-A and MAO-B isoforms function by the same hydride-transfer mechanism. We also considered a few point mutations of the "aromatic cage" tyrosine residue (Tyr444Phe, Tyr444Leu, Tyr444Trp, Tyr444His, and Tyr444Glu), and the calculated changes in the reaction barriers are in agreement with the experimental values, thus providing further support to the proposed mechanism.
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Affiliation(s)
- Matic Poberžnik
- Department of Physical and Organic Chemistry, Jožef Stefan Institute , Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Miha Purg
- Department of Cell and Molecular Biology, Uppsala Biomedical Centre , Husargatan 3, S-75124 Uppsala, Sweden
| | - Matej Repič
- Laboratory for Biocomputing and Bioinformatics, National Institute of Chemistry , Hajdrihova ulica 19, SI-1000 Ljubljana, Slovenia
| | - Janez Mavri
- Laboratory for Biocomputing and Bioinformatics, National Institute of Chemistry , Hajdrihova ulica 19, SI-1000 Ljubljana, Slovenia
| | - Robert Vianello
- Computational Organic Chemistry and Biochemistry Group, Ruđer Bošković Institute , Bijenička cesta 54, HR-10000 Zagreb, Croatia
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28
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Ramsay RR, Majekova M, Medina M, Valoti M. Key Targets for Multi-Target Ligands Designed to Combat Neurodegeneration. Front Neurosci 2016; 10:375. [PMID: 27597816 PMCID: PMC4992697 DOI: 10.3389/fnins.2016.00375] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 08/02/2016] [Indexed: 12/13/2022] Open
Abstract
HIGHLIGHTS Compounds that interact with multiple targets but minimally with the cytochrome P450 system (CYP) address the many factors leading to neurodegeneration.Acetyl- and Butyryl-cholineEsterases (AChE, BChE) and Monoamine Oxidases A/B (MAO A, MAO B) are targets for Multi-Target Designed Ligands (MTDL).ASS234 is an irreversible inhibitor of MAO A >MAO B and has micromolar potency against the cholinesterases.ASS234 is a poor CYP substrate in human liver, yielding the depropargylated metabolite.SMe1EC2, a stobadine derivative, showed high radical scavenging property, in vitro and in vivo giving protection in head trauma and diabetic damage of endothelium.Control of mitochondrial function and morphology by manipulating fission and fusion is emerging as a target area for therapeutic strategies to decrease the pathological outcome of neurodegenerative diseases. Growing evidence supports the view that neurodegenerative diseases have multiple and common mechanisms in their aetiologies. These multifactorial aspects have changed the broadly common assumption that selective drugs are superior to "dirty drugs" for use in therapy. This drives the research in studies of novel compounds that might have multiple action mechanisms. In neurodegeneration, loss of neuronal signaling is a major cause of the symptoms, so preservation of neurotransmitters by inhibiting the breakdown enzymes is a first approach. Acetylcholinesterase (AChE) inhibitors are the drugs preferentially used in AD and that one of these, rivastigmine, is licensed also for PD. Several studies have shown that monoamine oxidase (MAO) B, located mainly in glial cells, increases with age and is elevated in Alzheimer (AD) and Parkinson's Disease's (PD). Deprenyl, a MAO B inhibitor, significantly delays the initiation of levodopa treatment in PD patients. These indications underline that AChE and MAO are considered a necessary part of multi-target designed ligands (MTDL). However, both of these targets are simply symptomatic treatment so if new drugs are to prevent degeneration rather than compensate for loss of neurotransmitters, then oxidative stress and mitochondrial events must also be targeted. MAO inhibitors can protect neurons from apoptosis by mechanisms unrelated to enzyme inhibition. Understanding the involvement of MAO and other proteins in the induction and regulation of the apoptosis in mitochondria will aid progress toward strategies to prevent the loss of neurons. In general, the oxidative stress observed both in PD and AD indicate that antioxidant properties are a desirable part of MTDL molecules. After two or more properties are incorporated into one molecule, the passage from a lead compound to a therapeutic tool is strictly linked to its pharmacokinetic and toxicity. In this context the interaction of any new molecules with cytochrome P450 and other xenobiotic metabolic processes is a crucial point. The present review covers the biochemistry of enzymes targeted in the design of drugs against neurodegeneration and the cytochrome P450-dependent metabolism of MTDLs.
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Affiliation(s)
- Rona R. Ramsay
- Biomedical Sciences Research Complex, University of St. AndrewsSt. Andrews, UK
| | - Magdalena Majekova
- Department of Biochemical Pharmacology, Institute of Experimental Pharmacology and Toxicology, Slovak Academy of SciencesBratislava, Slovakia
| | - Milagros Medina
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias and BIFI, Universidad de ZaragozaZaragoza, Spain
| | - Massimo Valoti
- Dipartimento di Scienze della Vita, Università degli Studi di SienaSiena, Italy
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29
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Ramsay RR. Molecular aspects of monoamine oxidase B. Prog Neuropsychopharmacol Biol Psychiatry 2016; 69:81-9. [PMID: 26891670 DOI: 10.1016/j.pnpbp.2016.02.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/06/2016] [Accepted: 02/11/2016] [Indexed: 02/07/2023]
Abstract
Monoamine oxidases (MAO) influence the monoamine levels in brain by virtue of their role in neurotransmitter breakdown. MAO B is the predominant form in glial cells and in platelets. MAO B structure, function and kinetics are described as a background for the effect of alterations in its activity on behavior. The need to inhibit MAO B to combat decreased brain amines continues to drive the search for new drugs. Reversible and irreversible inhibitors are now designed using data-mining, computational screening, docking and molecular dynamics. Multi-target ligands designed to combat the elevated activity of MAO B in Alzheimer's and Parkinson's Diseases incorporate MAO inhibition (usually irreversible) as well as iron chelation, antioxidant or neuroprotective properties. The main focus of drug design is the catalytic activity of MAO, but the imidazoline I2 site in the entrance cavity of MAO B is also a pharmacological target. Endogenous regulation of MAO B expression is discussed briefly in light of new studies measuring mRNA, protein, or activity in healthy and degenerative samples, including the effect of DNA methylation on the expression. Overall, this review focuses on examples of recent research on the molecular aspects of the expression, activity, and inhibition of MAO B.
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Affiliation(s)
- Rona R Ramsay
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, United Kingdom.
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30
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Zaitseva II, Zaitsev SV, Berggren PO. The imidazoline compound RX871024 promotes insulinoma cell death independent of AMP-activated protein kinase inhibition. Invest New Drugs 2016; 34:522-9. [DOI: 10.1007/s10637-016-0362-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/18/2016] [Indexed: 11/29/2022]
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31
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Abstract
Accumulating evidence shows a relationship between the human MAO-B (hMAO-B) enzyme and neuropsychiatric/degenerative disorder, personality traits, type II alcoholism, borderline personality disorders, aggressiveness and violence in crime, obsessive-compulsive disorder, depression, suicide, schizophrenia, anorexia nervosa, migraine, dementia, and PD. Thus, MAO-B represents an attractive target for the treatment of a number of human diseases. The discovery, development, and therapeutic use of drugs that inhibit MAO-B are major challenges for future therapy. Various compounds and drugs that selectively target this isoform have been discovered recently. These agents are synthetic compounds or natural products and their analogues, including chalcones, pyrazoles, chromones, coumarins, xanthines, isatin derivatives, thiazolidindiones, (thiazol-2-yl)hydrazones, and analogues of marketed drugs. Despite considerable efforts in understanding the binding interaction with specific substrates or inhibitors, structural information available for the rational design of new hMAO-B inhibitors remains unsatisfactory. Therefore, the quest for novel, potent, and selective hMAO-B inhibitors remains of high interest.
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Affiliation(s)
- Simone Carradori
- Dipartimento Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma , Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Romano Silvestri
- Dipartimento Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma , Piazzale Aldo Moro 5, I-00185 Roma, Italy
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32
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Malcomson T, Yelekci K, Borrello MT, Ganesan A, Semina E, De Kimpe N, Mangelinckx S, Ramsay RR. cis-cyclopropylamines as mechanism-based inhibitors of monoamine oxidases. FEBS J 2015; 282:3190-8. [DOI: 10.1111/febs.13260] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/27/2015] [Accepted: 03/06/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas Malcomson
- Biomedical Sciences Research Complex; University of St Andrews; UK
| | - Kemal Yelekci
- Department of Bioinformatics and Genetics; Kadir Has University; Istanbul Turkey
| | | | - A. Ganesan
- School of Pharmacy; University of East Anglia; Norwich UK
| | - Elena Semina
- Department of Sustainable Organic Chemistry and Technology; Ghent University; Belgium
| | - Norbert De Kimpe
- Department of Sustainable Organic Chemistry and Technology; Ghent University; Belgium
| | - Sven Mangelinckx
- Department of Sustainable Organic Chemistry and Technology; Ghent University; Belgium
| | - Rona R. Ramsay
- Biomedical Sciences Research Complex; University of St Andrews; UK
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33
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Basile L, Pappalardo M, Guccione S, Milardi D, Ramsay RR. Computational Comparison of Imidazoline Association with the I2 Binding Site in Human Monoamine Oxidases. J Chem Inf Model 2014; 54:1200-7. [DOI: 10.1021/ci400346k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Livia Basile
- Etnalead
s.r.l., c/o EtnaBuilding, Scuola Superiore di Catania, Università degli Studi di Catania, via S. Nullo 5/i, I-95123 Catania, Italy
| | - Matteo Pappalardo
- Dipartimento
di Scienze Chimiche, Università degli Studi di Catania, Viale
A.Doria 6 Ed.3, Città Universitaria, I- 95125 Catania, Italy
| | - Salvatore Guccione
- Etnalead
s.r.l., c/o EtnaBuilding, Scuola Superiore di Catania, Università degli Studi di Catania, via S. Nullo 5/i, I-95123 Catania, Italy
- Dipartimento
di Scienze del Farmaco, Università degli Studi di Catania, Viale A.Doria 6 Ed. 2, Città Universitaria, I-95125 Catania, Italy
| | - Danilo Milardi
- IBB-CNR,
Istituto di Biostrutture e Bioimmagini, UOS di Catania c/o Dipartimento
di Scienze Chimiche, Università degli Studi di Catania, Viale
A.Doria 6 Ed.3, Città Universitaria, I- 95125 Catania, Italy
| | - Rona R. Ramsay
- Biomedical
Sciences Research Complex, University of St. Andrews, North Haugh, St. Andrews KY16 8QP, U.K
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34
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Monoamine oxidase A and B substrates: probing the pathway for drug development. Future Med Chem 2014; 6:697-717. [DOI: 10.4155/fmc.14.23] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Drug-discovery and -development efforts focused on the MAOs have increased at an accelerated rate over the past decade. Since the first crystal structure of human MAO-B was solved in 2002, over 40 additional structures have been reported and have helped define new, or confirm speculative, binding modes of inhibitors. The detailed mechanism of the MAO-catalyzed oxidation of amine substrates has not been fully elucidated, but its significance is central in the development of new mechanism-based inactivators. Novel fungal MAO-N variants derived from directed evolution strategies are enabling the production of new chiral amine products. Robust assays have been established for measuring MAO status in tissue and cells, while improved MAO radioligands are being deployed for PET imaging studies. This review will attempt to highlight the more recent and salient aspects of MAO research in drug discovery and development, with emphasis on substrates 'probing the pathway'.
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35
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Esteban G, Allan J, Samadi A, Mattevi A, Unzeta M, Marco-Contelles J, Binda C, Ramsay RR. Kinetic and structural analysis of the irreversible inhibition of human monoamine oxidases by ASS234, a multi-target compound designed for use in Alzheimer's disease. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1104-10. [PMID: 24642166 DOI: 10.1016/j.bbapap.2014.03.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/04/2014] [Accepted: 03/10/2014] [Indexed: 12/29/2022]
Abstract
Monoamine oxidases (MAO) and cholinesterases are validated targets in the design of drugs for the treatment of Alzheimer's disease. The multi-target compound N-((5-(3-(1-benzylpiperidin-4-yl)propoxy)-1-methyl-1H-indol-2-yl)methyl)-N-methylprop-2-yn-1-amine (ASS234), bearing the MAO-inhibiting propargyl group attached to a donepezil moiety that inhibits cholinesterases, retained activity against human acetyl- and butyryl-cholinesterases. The inhibition of MAO A and MAO B by ASS234 was characterized and compared to other known MAO inhibitors. ASS234 was almost as effective as clorgyline (kinact/KI=3×10(6) min(-1)M(-1)) and was shown by structural studies to form the same N5 covalent adduct with the FAD cofactor.
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Affiliation(s)
- Gerard Esteban
- Departamento de Bioquímica i Biología Molecular, Institute of Neuroscience, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Jennifer Allan
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 8QP, UK
| | - Abdelouahid Samadi
- Laboratorio de Química Medica (IQOG, CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain
| | - Andrea Mattevi
- Department of Biology and Biotechnology, University of Pavia, Pavia 27100, Italy
| | - Mercedes Unzeta
- Departamento de Bioquímica i Biología Molecular, Institute of Neuroscience, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - José Marco-Contelles
- Laboratorio de Química Medica (IQOG, CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain
| | - Claudia Binda
- Department of Biology and Biotechnology, University of Pavia, Pavia 27100, Italy.
| | - Rona R Ramsay
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 8QP, UK.
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Juárez-Jiménez J, Mendes E, Galdeano C, Martins C, Silva DB, Marco-Contelles J, do Carmo Carreiras M, Luque FJ, Ramsay RR. Exploring the structural basis of the selective inhibition of monoamine oxidase A by dicarbonitrile aminoheterocycles: role of Asn181 and Ile335 validated by spectroscopic and computational studies. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1844:389-97. [PMID: 24247011 DOI: 10.1016/j.bbapap.2013.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 11/07/2013] [Accepted: 11/09/2013] [Indexed: 10/26/2022]
Abstract
Since cyanide potentiates the inhibitory activity of several monoamine oxidase (MAO) inhibitors, a series of carbonitrile-containing aminoheterocycles was examined to explore the role of nitriles in determining the inhibitory activity against MAO. Dicarbonitrile aminofurans were found to be potent, selective inhibitors against MAO A. The origin of the MAO A selectivity was identified by combining spectroscopic and computational methods. Spectroscopic changes induced in MAO A by mono- and dicarbonitrile inhibitors were different, providing experimental evidence for distinct binding modes to the enzyme. Similar differences were also found between the binding of dicarbonitrile compounds to MAO A and to MAO B. Stabilization of the flavin anionic semiquinone by monocarbonitrile compounds, but destabilization by dicarbonitriles, provided further support to the distinct binding modes of these compounds and their interaction with the flavin ring. Molecular modeling studies supported the role played by the nitrile and amino groups in anchoring the inhibitor to the binding cavity. In particular, the results highlight the role of Asn181 and Ile335 in assisting the interaction of the nitrile-containing aminofuran ring. The network of interactions afforded by the specific attachment of these functional groups provides useful guidelines for the design of selective, reversible MAO A inhibitors.
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Affiliation(s)
- Jordi Juárez-Jiménez
- Department of Physical Chemistry, Faculty of Pharmacy and Institute of Biomedicine (IBUB), University of Barcelona, Avda. Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain
| | - Eduarda Mendes
- iMed.UL - Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Avda. Prof. Gama Pinto, 1649-003 Lisbon, Portugal
| | - Carles Galdeano
- Department of Physical Chemistry, Faculty of Pharmacy and Institute of Biomedicine (IBUB), University of Barcelona, Avda. Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain
| | - Carla Martins
- iMed.UL - Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Avda. Prof. Gama Pinto, 1649-003 Lisbon, Portugal
| | - Daniel B Silva
- iMed.UL - Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Avda. Prof. Gama Pinto, 1649-003 Lisbon, Portugal
| | - José Marco-Contelles
- Laboratorio de Radicales Libres y Química Computacional, Instituto de Química Orgánica General, Consejo Superior de Investigaciones Científicas, c/. Juan de la Cierva 3, 28006 Madrid, Spain
| | - Maria do Carmo Carreiras
- iMed.UL - Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Avda. Prof. Gama Pinto, 1649-003 Lisbon, Portugal
| | - F Javier Luque
- Department of Physical Chemistry, Faculty of Pharmacy and Institute of Biomedicine (IBUB), University of Barcelona, Avda. Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain
| | - Rona R Ramsay
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews KY16 9ST, UK.
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Montolio M, Gregori-Puigjané E, Pineda D, Mestres J, Navarro P. Identification of small molecule inhibitors of amyloid β-induced neuronal apoptosis acting through the imidazoline I(2) receptor. J Med Chem 2012; 55:9838-46. [PMID: 23098038 DOI: 10.1021/jm301055g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aberrant activation of signaling pathways plays a pivotal role in central nervous system disorders, such as Alzheimer's disease (AD). Using a combination of virtual screening and experimental testing, novel small molecule inhibitors of tPA-mediated extracellular signal-regulated kinase (Erk)1/2 activation were identified that provide higher levels of neuroprotection from Aβ-induced apoptosis than Memantine, the most recently FDA-approved drug for AD treatment. Subsequent target deconvolution efforts revealed that they all share low micromolar affinity for the imidazoline I(2) receptor, while being devoid of any significant affinity to a list of AD-relevant targets, including the N-methyl-d-aspartate receptor (NMDAR), acetylcholinesterase (AChE), and monoamine oxidase B (MAO-B). Targeting the imidazoline I(2) receptor emerges as a new mechanism of action to inhibit tPA-induced signaling in neurons for the treatment of AD and other neurodegenerative diseases.
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Affiliation(s)
- Marisol Montolio
- Cancer Research Program, IMIM-Hospital del Mar Research Institute and University Pompeu Fabra, Parc de Recerca Biomèdica (PRBB), Doctor Aiguader 88, 08003 Barcelona, Catalonia, Spain
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Wichitnithad W, O’Callaghan JP, Miller DB, Train BC, Callery PS. Time-dependent slowly-reversible inhibition of monoamine oxidase A by N-substituted 1,2,3,6-tetrahydropyridines. Bioorg Med Chem 2011; 19:7482-92. [DOI: 10.1016/j.bmc.2011.10.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/06/2011] [Accepted: 10/14/2011] [Indexed: 10/16/2022]
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39
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Ramsay RR, Olivieri A, Holt A. An improved approach to steady-state analysis of monoamine oxidases. J Neural Transm (Vienna) 2011; 118:1003-19. [DOI: 10.1007/s00702-011-0657-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 05/05/2011] [Indexed: 11/30/2022]
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40
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Ferrari F, Fiorentino S, Mennuni L, Garofalo P, Letari O, Mandelli S, Giordani A, Lanza M, Caselli G. Analgesic efficacy of CR4056, a novel imidazoline-2 receptor ligand, in rat models of inflammatory and neuropathic pain. J Pain Res 2011; 4:111-25. [PMID: 21647215 PMCID: PMC3100226 DOI: 10.2147/jpr.s18353] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Indexed: 12/02/2022] Open
Abstract
Two decades of investigations have failed to unequivocally clarify the functions and the molecular nature of imidazoline-2 receptors (I2R). However, there is robust pharmacological evidence for the functional modulation of monoamino oxidase (MAO) and other important enzyme activities by I2 site ligands. Some compounds of this class proved to be active experimental tools in preventing both experimental pain and opioid tolerance and dependence. Unfortunately, even though these compounds bind with high potency to central I2 sites, they fail to represent a valid clinical opportunity due to their pharmacokinetic, selectivity or side-effects profile. This paper presents the preclinical profile of a novel I2 ligand (2-phenyl-6-(1H-imidazol-1yl) quinazoline; [CR4056]) that selectively inhibits the activity of human recombinant MAO-A in a concentration-dependent manner. A sub-chronic four day oral treatment of CR4056 increased norepinephrine (NE) tissue levels both in the rat cerebral cortex (63.1% ±4.2%; P < 0.05) and lumbar spinal cord (51.3% ± 6.7%; P < 0.05). In the complete Freund’s adjuvant (CFA) rat model of inflammatory pain, CR4056 was found to be orally active (ED50 = 5.8 mg/kg, by mouth [p.o.]). In the acute capsaicin model, CR4056 completely blocked mechanical hyperalgesia in the injured hind paw (ED50 = 4.1 mg/kg, p.o.; ED100 = 17.9 mg/kg, p.o.). This effect was dose-dependently antagonized by the non-selective imidazoline I2/α2 antagonist idazoxan. In rat models of neuropathic pain, oral administration of CR4056 significantly attenuated mechanical hyperalgesia and allodynia. In summary, the present study suggests a novel pharmacological opportunity for inflammatory and/or neuropathic pain treatment based on selective interaction with central imidazoline-2 receptors.
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Affiliation(s)
- Flora Ferrari
- Department of Pharmacology and Toxicology, S.p.A., Monza (MB), Italy
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41
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Crystallographic snapshots of the complete reaction cycle of nicotine degradation by an amine oxidase of the monoamine oxidase (MAO) family. Proc Natl Acad Sci U S A 2011; 108:4800-5. [PMID: 21383134 DOI: 10.1073/pnas.1016684108] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
FAD-linked oxidases constitute a class of enzymes which catalyze dehydrogenation as a fundamental biochemical reaction, followed by reoxidation of reduced flavin. Here, we present high-resolution crystal structures showing the flavoenzyme 6-hydroxy-l-nicotine oxidase in action. This enzyme was trapped during catalytic degradation of the native substrate in a sequence of discrete reaction states corresponding to the substrate-reduced enzyme, a complex of the enzyme with the intermediate enamine product and formation of the final aminoketone product. The inactive d-stereoisomer binds in mirror symmetry with respect to the catalytic axis, revealing absolute stereospecificity of hydrogen transfer to the flavin. The structural data suggest deprotonation of the substrate when bound at the active site, an overall binary complex mechanism and oxidation by direct hydride transfer. The amine nitrogen has a critical role in the dehydrogenation step and may activate carbocation formation at the α-carbon via delocalization from the lone pair to σ* C(α)-H. Enzymatically assisted hydrolysis of the intermediate product occurs at a remote (P site) cavity. Substrate entry and product exit follow different paths. Structural and kinetic data suggest that substrate can also bind to the reduced enzyme, associated with slower reoxidation as compared to the rate of reoxidation of free enzyme. The results are of general relevance for the mechanisms of flavin amine oxidases.
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42
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Tipton KF, Davey GP, McDonald AG. Kinetic behavior and reversible inhibition of monoamine oxidases--enzymes that many want dead. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 100:43-64. [PMID: 21971002 DOI: 10.1016/b978-0-12-386467-3.00003-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Monoamine oxidase (MAO) inhibitors have proven to be valuable tools in pharmacology and therapeutics. This account concerns the behavior of the different types of reversible inhibitor and how an understanding of the kinetic mechanisms of MAO may help in their design.
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Affiliation(s)
- Keith F Tipton
- Department of Biochemistry, Trinity College, Dublin, Ireland
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