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Bueschbell B, Magalhães PR, Barreto CA, Melo R, Schiedel AC, Machuqueiro M, Moreira IS. The World of GPCR dimers - Mapping dopamine receptor D 2 homodimers in different activation states and configuration arrangements. Comput Struct Biotechnol J 2023; 21:4336-4353. [PMID: 37711187 PMCID: PMC10497915 DOI: 10.1016/j.csbj.2023.08.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/16/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are known to dimerize, but the molecular and structural basis of GPCR dimers is not well understood. In this study, we developed a computational framework to generate models of symmetric and asymmetric GPCR dimers using different monomer activation states and identified their most likely interfaces with molecular details. We chose the dopamine receptor D2 (D2R) homodimer as a case study because of its biological relevance and the availability of structural information. Our results showed that transmembrane domains 4 and 5 (TM4 and TM5) are mostly found at the dimer interface of the D2R dimer and that these interfaces have a subset of key residues that are mostly nonpolar from TM4 and TM5, which was in line with experimental studies. In addition, TM2 and TM3 appear to be relevant for D2R dimers. In some cases, the inactive configuration is unaffected by the partnered protomer, whereas in others, the active protomer adopts the properties of an inactive receptor. Additionally, the β-arrestin configuration displayed the properties of an active receptor in the absence of an agonist, suggesting that a switch to another meta-state during dimerization occurred. Our findings are consistent with the experimental data, and this method can be adapted to study heterodimers and potentially extended to include additional proteins such as G proteins or β-arrestins. In summary, this approach provides insight into the impact of the conformational status of partnered protomers on the overall quaternary GPCR macromolecular structure and dynamics.
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Affiliation(s)
- Beatriz Bueschbell
- CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, 3000-456 Coimbra, Portugal
- IIIs-Institute for Interdisciplinary Research, University of Coimbra, 3000-456 Coimbra, Portugal
| | - Pedro R. Magalhães
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande C8 bdg, 1749-016 Lisboa, Portugal
| | - Carlos A.V. Barreto
- CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, 3000-456 Coimbra, Portugal
- IIIs-Institute for Interdisciplinary Research, University of Coimbra, 3000-456 Coimbra, Portugal
| | - Rita Melo
- CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, 3000-456 Coimbra, Portugal
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, University of Coimbra, Coimbra, Portugal
| | - Anke C. Schiedel
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, D-53121 Bonn, Germany
| | - Miguel Machuqueiro
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande C8 bdg, 1749-016 Lisboa, Portugal
| | - Irina S. Moreira
- Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
- CNC-Center for Neuroscience and Cell Biology, CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-535 Coimbra, Portugal
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2
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Caniceiro AB, Bueschbell B, Schiedel AC, Moreira IS. Class A and C GPCR Dimers in Neurodegenerative Diseases. Curr Neuropharmacol 2022; 20:2081-2141. [PMID: 35339177 PMCID: PMC9886835 DOI: 10.2174/1570159x20666220327221830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/21/2022] [Accepted: 03/23/2022] [Indexed: 11/22/2022] Open
Abstract
Neurodegenerative diseases affect over 30 million people worldwide with an ascending trend. Most individuals suffering from these irreversible brain damages belong to the elderly population, with onset between 50 and 60 years. Although the pathophysiology of such diseases is partially known, it remains unclear upon which point a disease turns degenerative. Moreover, current therapeutics can treat some of the symptoms but often have severe side effects and become less effective in long-term treatment. For many neurodegenerative diseases, the involvement of G proteincoupled receptors (GPCRs), which are key players of neuronal transmission and plasticity, has become clearer and holds great promise in elucidating their biological mechanism. With this review, we introduce and summarize class A and class C GPCRs, known to form heterodimers or oligomers to increase their signalling repertoire. Additionally, the examples discussed here were shown to display relevant alterations in brain signalling and had already been associated with the pathophysiology of certain neurodegenerative diseases. Lastly, we classified the heterodimers into two categories of crosstalk, positive or negative, for which there is known evidence.
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Affiliation(s)
- Ana B. Caniceiro
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; ,These authors contributed equally to this work.
| | - Beatriz Bueschbell
- PhD Programme in Experimental Biology and Biomedicine, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Casa Costa Alemão, 3030-789 Coimbra, Portugal; ,These authors contributed equally to this work.
| | - Anke C. Schiedel
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, D-53121 Bonn, Germany;
| | - Irina S. Moreira
- University of Coimbra, Department of Life Sciences, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal; ,Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, 3004-504 Coimbra, Portugal,Address correspondence to this author at the Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, 3004-504 Coimbra, Portugal; E-mail:
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3
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Gao S, Sylvester K, Song L, Claff T, Jing L, Woodson M, Weiße RH, Cheng Y, Schäkel L, Petry M, Gütschow M, Schiedel AC, Sträter N, Kang D, Xu S, Toth K, Tavis J, Tollefson AE, Müller CE, Liu X, Zhan P. Discovery and Crystallographic Studies of Trisubstituted Piperazine Derivatives as Non-Covalent SARS-CoV-2 Main Protease Inhibitors with High Target Specificity and Low Toxicity. J Med Chem 2022; 65:13343-13364. [PMID: 36107752 PMCID: PMC9491405 DOI: 10.1021/acs.jmedchem.2c01146] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Indexed: 01/08/2023]
Abstract
The continuous spread of SARS-CoV-2 calls for more direct-acting antiviral agents to combat the highly infectious variants. The main protease (Mpro) is an promising target for anti-SARS-CoV-2 drug design. Here, we report the discovery of potent non-covalent non-peptide Mpro inhibitors featuring a 1,2,4-trisubstituted piperazine scaffold. We systematically modified the non-covalent hit MCULE-5948770040 by structure-based rational design combined with multi-site binding and privileged structure assembly strategies. The optimized compound GC-14 inhibits Mpro with high potency (IC50 = 0.40 μM) and displays excellent antiviral activity (EC50 = 1.1 μM), being more potent than Remdesivir. Notably, GC-14 exhibits low cytotoxicity (CC50 > 100 μM) and excellent target selectivity for SARS-CoV-2 Mpro (IC50 > 50 μM for cathepsins B, F, K, L, and caspase 3). X-ray co-crystal structures prove that the inhibitors occupy multiple subpockets by critical non-covalent interactions. These studies may provide a basis for developing a more efficient and safer therapy for COVID-19.
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Affiliation(s)
- Shenghua Gao
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
- Shenzhen Research Institute of Shandong
University, A301 Virtual University Park in South District of Shenzhen,
Guangdong518057, P. R. China
| | - Katharina Sylvester
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Letian Song
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
| | - Tobias Claff
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Lanlan Jing
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
| | - Molly Woodson
- Department of Molecular Microbiology and Immunology,
Saint Louis University School of Medicine, St. Louis,
Missouri63103, United States
- Saint Louis University Institute for Drug
and Biotherapeutic Innovation, St. Louis, Missouri63103, United
States
| | - Renato H. Weiße
- Institute of Bioanalytical Chemistry, Center for
Biotechnology and Biomedicine, Leipzig University, Deutscher
Platz 5, Leipzig04103, Germany
| | - Yusen Cheng
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
| | - Laura Schäkel
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Marvin Petry
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Michael Gütschow
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Anke C. Schiedel
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Norbert Sträter
- Institute of Bioanalytical Chemistry, Center for
Biotechnology and Biomedicine, Leipzig University, Deutscher
Platz 5, Leipzig04103, Germany
| | - Dongwei Kang
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
| | - Shujing Xu
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
| | - Karoly Toth
- Department of Molecular Microbiology and Immunology,
Saint Louis University School of Medicine, St. Louis,
Missouri63103, United States
- Saint Louis University Institute for Drug
and Biotherapeutic Innovation, St. Louis, Missouri63103, United
States
| | - John Tavis
- Department of Molecular Microbiology and Immunology,
Saint Louis University School of Medicine, St. Louis,
Missouri63103, United States
- Saint Louis University Institute for Drug
and Biotherapeutic Innovation, St. Louis, Missouri63103, United
States
| | - Ann E. Tollefson
- Department of Molecular Microbiology and Immunology,
Saint Louis University School of Medicine, St. Louis,
Missouri63103, United States
- Saint Louis University Institute for Drug
and Biotherapeutic Innovation, St. Louis, Missouri63103, United
States
| | - Christa E. Müller
- PharmaCenter Bonn & Pharmaceutical Institute,
Department of Pharmaceutical & Medicinal Chemistry, University of
Bonn, An der Immenburg 4, Bonn53113, Germany
| | - Xinyong Liu
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
| | - Peng Zhan
- Department of Medicinal Chemistry, Key Laboratory of
Chemical Biology, Ministry of Education, School of Pharmaceutical Sciences,
Shandong University, Ji’nan250012,
China
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Bueschbell B, Manga P, Schiedel AC. The Many Faces of G Protein-Coupled Receptor 143, an Atypical Intracellular Receptor. Front Mol Biosci 2022; 9:873777. [PMID: 35495622 PMCID: PMC9039016 DOI: 10.3389/fmolb.2022.873777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/10/2022] [Indexed: 12/24/2022] Open
Abstract
GPCRs transform extracellular stimuli into a physiological response by activating an intracellular signaling cascade initiated via binding to G proteins. Orphan G protein-coupled receptors (GPCRs) hold the potential to pave the way for development of new, innovative therapeutic strategies. In this review we will introduce G protein-coupled receptor 143 (GPR143), an enigmatic receptor in terms of classification within the GPCR superfamily and localization. GPR143 has not been assigned to any of the GPCR families due to the lack of common structural motifs. Hence we will describe the most important motifs of classes A and B and compare them to the protein sequence of GPR143. While a precise function for the receptor has yet to be determined, the protein is expressed abundantly in pigment producing cells. Many GPR143 mutations cause X-linked Ocular Albinism Type 1 (OA1, Nettleship-Falls OA), which results in hypopigmentation of the eyes and loss of visual acuity due to disrupted visual system development and function. In pigment cells of the skin, loss of functional GPR143 results in abnormally large melanosomes (organelles in which pigment is produced). Studies have shown that the receptor is localized internally, including at the melanosomal membrane, where it may function to regulate melanosome size and/or facilitate protein trafficking to the melanosome through the endolysosomal system. Numerous additional roles have been proposed for GPR143 in determining cancer predisposition, regulation of blood pressure, development of macular degeneration and signaling in the brain, which we will briefly describe as well as potential ligands that have been identified. Furthermore, GPR143 is a promiscuous receptor that has been shown to interact with multiple other melanosomal proteins and GPCRs, which strongly suggests that this orphan receptor is likely involved in many different physiological actions.
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Affiliation(s)
- Beatriz Bueschbell
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology, Grossman School of Medicine, New York University, New York City, NY, United States
| | - Anke C. Schiedel
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, Bonn, Germany
- *Correspondence: Anke C. Schiedel,
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5
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Bueschbell B, Manga P, Penner E, Schiedel AC. Evidence for Protein-Protein Interaction between Dopamine Receptors and the G Protein-Coupled Receptor 143. Int J Mol Sci 2021; 22:ijms22158328. [PMID: 34361094 PMCID: PMC8348196 DOI: 10.3390/ijms22158328] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/12/2022] Open
Abstract
Protein-protein interactions between G protein-coupled receptors (GPCRs) can augment their functionality and increase the repertoire of signaling pathways they regulate. New therapeutics designed to modulate such interactions may allow for targeting of a specific GPCR activity, thus reducing potential for side effects. Dopamine receptor (DR) heteromers are promising candidates for targeted therapy of neurological conditions such as Parkinson's disease since current treatments can have severe side effects. To facilitate development of such therapies, it is necessary to identify the various DR binding partners. We report here a new interaction partner for DRD2 and DRD3, the orphan receptor G protein-coupled receptor 143 (GPR143), an atypical GPCR that plays multiple roles in pigment cells and is expressed in several regions of the brain. We previously demonstrated that the DRD2/ DRD3 antagonist pimozide also modulates GPR143 activity. Using confocal microscopy and two FRET methods, we observed that the DRs and GPR143 colocalize and interact at intracellular membranes. Furthermore, co-expression of wildtype GPR143 resulted in a 57% and 67% decrease in DRD2 and DRD3 activity, respectively, as determined by β-Arrestin recruitment assay. GPR143-DR dimerization may negatively modulate DR activity by changing affinity for dopamine or delaying delivery of the DRs to the plasma membrane.
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Affiliation(s)
- Beatriz Bueschbell
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal;
- PhD Programme in Experimental Biology and Biomedicine, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Casa Costa Alemão, 3030-789 Coimbra, Portugal
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology, Grossman School of Medicine, New York University, New York, NY 10016, USA;
| | - Erika Penner
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, D-53121 Bonn, Germany;
| | - Anke C. Schiedel
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, D-53121 Bonn, Germany;
- Correspondence:
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6
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Breidenbach J, Lemke C, Pillaiyar T, Schäkel L, Al Hamwi G, Diett M, Gedschold R, Geiger N, Lopez V, Mirza S, Namasivayam V, Schiedel AC, Sylvester K, Thimm D, Vielmuth C, Phuong Vu L, Zyulina M, Bodem J, Gütschow M, Müller CE. Targeting the Main Protease of SARS-CoV-2: From the Establishment of High Throughput Screening to the Design of Tailored Inhibitors. Angew Chem Int Ed Engl 2021; 60:10423-10429. [PMID: 33655614 PMCID: PMC8014119 DOI: 10.1002/anie.202016961] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/08/2021] [Indexed: 12/11/2022]
Abstract
The main protease of SARS‐CoV‐2 (Mpro), the causative agent of COVID‐19, constitutes a significant drug target. A new fluorogenic substrate was kinetically compared to an internally quenched fluorescent peptide and shown to be ideally suitable for high throughput screening with recombinantly expressed Mpro. Two classes of protease inhibitors, azanitriles and pyridyl esters, were identified, optimized and subjected to in‐depth biochemical characterization. Tailored peptides equipped with the unique azanitrile warhead exhibited concomitant inhibition of Mpro and cathepsin L, a protease relevant for viral cell entry. Pyridyl indole esters were analyzed by a positional scanning. Our focused approach towards Mpro inhibitors proved to be superior to virtual screening. With two irreversible inhibitors, azanitrile 8 (kinac/Ki=37 500 m−1 s−1, Ki=24.0 nm) and pyridyl ester 17 (kinac/Ki=29 100 m−1 s−1, Ki=10.0 nm), promising drug candidates for further development have been discovered.
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Affiliation(s)
- Julian Breidenbach
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Carina Lemke
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Thanigaimalai Pillaiyar
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails.,Present address: Pharmaceutical Institute, Pharmaceutical Chemistry, Eberhard-Karls-University Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany
| | - Laura Schäkel
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Ghazl Al Hamwi
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Miriam Diett
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Robin Gedschold
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Nina Geiger
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Versbacher Strasse 7, 97078, Würzburg, Germany
| | - Vittoria Lopez
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Salahuddin Mirza
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Vigneshwaran Namasivayam
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Anke C Schiedel
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Katharina Sylvester
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Dominik Thimm
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Christin Vielmuth
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Lan Phuong Vu
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Maria Zyulina
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Jochen Bodem
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Versbacher Strasse 7, 97078, Würzburg, Germany
| | - Michael Gütschow
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
| | - Christa E Müller
- Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany), E-mails
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7
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Breidenbach J, Lemke C, Pillaiyar T, Schäkel L, Al Hamwi G, Diett M, Gedschold R, Geiger N, Lopez V, Mirza S, Namasivayam V, Schiedel AC, Sylvester K, Thimm D, Vielmuth C, Phuong Vu L, Zyulina M, Bodem J, Gütschow M, Müller CE. Die Hauptprotease von SARS‐CoV‐2 als Zielstruktur: Von der Etablierung eines Hochdurchsatz‐Screenings zum Design maßgeschneiderter Inhibitoren. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Julian Breidenbach
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Carina Lemke
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Thanigaimalai Pillaiyar
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
- Aktuelle Adresse: Pharmazeutisches Institut Pharmazeutische Chemie Eberhard-Karls-Universität Tübingen Auf der Morgenstelle 8 72076 Tübingen Deutschland
| | - Laura Schäkel
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Ghazl Al Hamwi
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Miriam Diett
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Robin Gedschold
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Nina Geiger
- Institut für Virologie und Immunobiologie Julius-Maximilians-Universität Würzburg Versbacher Straße 7 97078 Würzburg Deutschland
| | - Vittoria Lopez
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Salahuddin Mirza
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Vigneshwaran Namasivayam
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Anke C. Schiedel
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Katharina Sylvester
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Dominik Thimm
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Christin Vielmuth
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Lan Phuong Vu
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Maria Zyulina
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Jochen Bodem
- Institut für Virologie und Immunobiologie Julius-Maximilians-Universität Würzburg Versbacher Straße 7 97078 Würzburg Deutschland
| | - Michael Gütschow
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
| | - Christa E. Müller
- Pharmazeutisches Institut Pharmazeutische & Medizinische Chemie Rheinische Friedrich-Wilhelms-Universität Bonn An der Immenburg 4 53121 Bonn Deutschland
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8
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De Filippo E, Hinz S, Pellizzari V, Deganutti G, El-Tayeb A, Navarro G, Franco R, Moro S, Schiedel AC, Müller CE. A2A and A2B adenosine receptors: The extracellular loop 2 determines high (A2A) or low affinity (A2B) for adenosine. Biochem Pharmacol 2020; 172:113718. [DOI: 10.1016/j.bcp.2019.113718] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 11/13/2019] [Indexed: 12/21/2022]
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9
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Bueschbell B, Barreto CAV, Preto AJ, Schiedel AC, Moreira IS. A Complete Assessment of Dopamine Receptor- Ligand Interactions through Computational Methods. Molecules 2019; 24:E1196. [PMID: 30934701 PMCID: PMC6479630 DOI: 10.3390/molecules24071196] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/21/2019] [Accepted: 03/23/2019] [Indexed: 12/22/2022] Open
Abstract
Background: Selectively targeting dopamine receptors (DRs) has been a persistent challenge in the last years for the development of new treatments to combat the large variety of diseases involving these receptors. Although, several drugs have been successfully brought to market, the subtype-specific binding mode on a molecular basis has not been fully elucidated. Methods: Homology modeling and molecular dynamics were applied to construct robust conformational models of all dopamine receptor subtypes (D₁-like and D₂-like). Fifteen structurally diverse ligands were docked. Contacts at the binding pocket were fully described in order to reveal new structural findings responsible for selective binding to DR subtypes. Results: Residues of the aromatic microdomain were shown to be responsible for the majority of ligand interactions established to all DRs. Hydrophobic contacts involved a huge network of conserved and non-conserved residues between three transmembrane domains (TMs), TM2-TM3-TM7. Hydrogen bonds were mostly mediated by the serine microdomain. TM1 and TM2 residues were main contributors for the coupling of large ligands. Some amino acid groups form electrostatic interactions of particular importance for D₁R-like selective ligands binding. Conclusions: This in silico approach was successful in showing known receptor-ligand interactions as well as in determining unique combinations of interactions, which will support mutagenesis studies to improve the design of subtype-specific ligands.
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Affiliation(s)
- Beatriz Bueschbell
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, D-53121 Bonn, Germany.
| | - Carlos A V Barreto
- Center for Neuroscience and Cell Biology, UC- Biotech Parque Tecnológico de Cantanhede, Núcleo 04, Lote B, 3060-197 Cantanhede, Portugal.
| | - António J Preto
- Center for Neuroscience and Cell Biology, UC- Biotech Parque Tecnológico de Cantanhede, Núcleo 04, Lote B, 3060-197 Cantanhede, Portugal.
| | - Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, D-53121 Bonn, Germany.
| | - Irina S Moreira
- Center for Neuroscience and Cell Biology, UC- Biotech Parque Tecnológico de Cantanhede, Núcleo 04, Lote B, 3060-197 Cantanhede, Portugal.
- Institute for Interdisciplinary Research, University of Coimbra, 3004-531 Coimbra, Portugal.
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10
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Schiedel AC, Kose M, Barreto C, Bueschbell B, Morra G, Sensoy O, Moreira IS. Prediction and Targeting of Interaction Interfaces in G-protein Coupled Receptor Oligomers. Curr Top Med Chem 2018; 18:714-746. [PMID: 29866008 DOI: 10.2174/1568026618666180604082610] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Communication within a protein complex is mediated by physical interactions made among the protomers. Evidence for both the allosteric regulation present among the protomers of the protein oligomer and of the direct effect of membrane composition on this regulation has made it essential to investigate the underlying molecular mechanism that drives oligomerization, the type of interactions present within the complex, and to determine the identity of the interaction interface. This knowledge allows a holistic understanding of dynamics and also modulation of the function of the resulting oligomers/signalling complexes. G-Protein-Coupled Receptors (GPCRs), which are targeted by 40% of currently prescribed drugs in the market, are widely involved in the formation of such physiological oligomers/signalling complexes. SCOPE This review highlights the importance of studying Protein-Protein Interactions (PPI) by using a combination of data obtained from cutting-edge experimental and computational methods that were developed for this purpose. In particular, we focused on interaction interfaces found at GPCR oligomers as well as signalling complexes, since any problem associated with these interactions causes the onset of various crucial diseases. CONCLUSION In order to have a holistic mechanistic understanding of allosteric PPIs that drive the formation of GPCR oligomers and also to determine the composition of interaction interfaces with respect to different membrane compositions, it is essential to combine both relevant experimental and computational data. In this way, efficient and specific targeting of these interaction interfaces in oligomers/ complexes can be achieved. Thus, effective therapeutic molecules with fewer side effects can be designed to modulate the function of these physiologically important receptor family.
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Affiliation(s)
- Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Meryem Kose
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Carlos Barreto
- Data-driven Molecular Design, CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Beatriz Bueschbell
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Giulia Morra
- Weill-Cornell Medical College, Department of Physiology and Biophysics, 1300 York Ave, New York, NY 10065, United States.,ICRM-CNR Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco 9, 20131 Milano, Italy
| | - Ozge Sensoy
- Istanbul Medipol University, The School of Engineering and Natural Sciences, 34810, Istanbul, Turkey
| | - Irina S Moreira
- Data-driven Molecular Design, CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Bijvoet Center for Biomolecular Research, Faculty of Science - Chemistry, Utrecht University, Utrecht, 3584CH, Netherlands
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11
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Hinz S, Navarro G, Borroto-Escuela D, Seibt BF, Ammon YC, de Filippo E, Danish A, Lacher SK, Červinková B, Rafehi M, Fuxe K, Schiedel AC, Franco R, Müller CE. Adenosine A 2A receptor ligand recognition and signaling is blocked by A 2B receptors. Oncotarget 2018; 9:13593-13611. [PMID: 29568380 PMCID: PMC5862601 DOI: 10.18632/oncotarget.24423] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/30/2018] [Indexed: 12/13/2022] Open
Abstract
The adenosine receptor (AR) subtypes A2A and A2B are rhodopsin-like Gs protein-coupled receptors whose expression is highly regulated under pathological, e.g. hypoxic, ischemic and inflammatory conditions. Both receptors play important roles in inflammatory and neurodegenerative diseases, are blocked by caffeine, and have now become major drug targets in immuno-oncology. By Förster resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET), bimolecular fluorescence complementation (BiFC) and proximity ligation assays (PLA) we demonstrated A2A-A2BAR heteromeric complex formation. Moreover we observed a dramatically altered pharmacology of the A2AAR when co-expressed with the A2BAR (A2B ≥ A2A) in recombinant as well as in native cells. In the presence of A2BARs, A2A-selective ligands lost high affinity binding to A2AARs and displayed strongly reduced potency in cAMP accumulation and dynamic mass redistribution (DMR) assays. These results have major implications for the use of A2AAR ligands as drugs as they will fail to modulate the receptor in an A2A-A2B heteromer context. Accordingly, A2A-A2BAR heteromers represent novel pharmacological targets.
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Affiliation(s)
- Sonja Hinz
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Gemma Navarro
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | | | - Benjamin F Seibt
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - York-Christoph Ammon
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Elisabetta de Filippo
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Azeem Danish
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Svenja K Lacher
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Barbora Červinková
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Muhammad Rafehi
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Rafael Franco
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
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12
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De Filippo E, Manga P, Schiedel AC. Author Response: Comment on "Identification of Novel G Protein-Coupled Receptor 143 Ligands as Pharmacologic Tools for Investigating X-Linked Ocular Albinism". Invest Ophthalmol Vis Sci 2017; 58:4735-4736. [PMID: 28910827 PMCID: PMC5600133 DOI: 10.1167/iovs.17-22810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, New York, United States; and the.,Department of Cell Biology, New York University School of Medicine, New York, New York, United States
| | - Anke C Schiedel
- Pharmaceutical Chemistry I, PharmaCenter Bonn, University of Bonn, Bonn, Germany
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13
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De Filippo E, Manga P, Schiedel AC. Identification of Novel G Protein-Coupled Receptor 143 Ligands as Pharmacologic Tools for Investigating X-Linked Ocular Albinism. Invest Ophthalmol Vis Sci 2017. [PMID: 28632878 PMCID: PMC5482243 DOI: 10.1167/iovs.16-21128] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Purpose GPR143 regulates melanosome biogenesis and organelle size in pigment cells. The mechanisms underlying receptor function remain unclear. G protein–coupled receptors (GPCRs) are excellent pharmacologic targets; thus, we developed and applied a screening approach to identify potential GPR143 ligands and chemical modulators. Methods GPR143 interacts with β-arrestin; we therefore established a β-arrestin recruitment assay to screen for compounds that modulate activity. Because GPR143 is localized intracellularly, screening with the wild-type receptor would be restricted to agents absorbed by the cell. For the screen we used a mutant receptor, which shows similar basal activity as the wild type but traffics to the plasma membrane. We tested two compound libraries and investigated validated hits for their effects on melanocyte pigmentation. Results GPR143, which showed high constitutive activity in the β-arrestin assay, was inhibited by several compounds. The three validated inhibitors (pimozide, niclosamide, and ethacridine lactate) were assessed for impact on melanocytes. Pigmentation and expression of tyrosinase, a key melanogenic enzyme, were reduced by all compounds. Because GPR143 appears to be constitutively active, these compounds may turn off its activity. Conclusions X-linked ocular albinism type I, characterized by developmental eye defects, results from GPR143 mutations. Identifying pharmacologic agents that modulate GPR143 activity will contribute significantly to our understanding of its function and provide novel tools with which to study GPCRs in melanocytes and retinal pigment epithelium. Pimozide, one of three GPR143 inhibitors identified in this study, maybe be a good lead structure for development of more potent compounds and provide a platform for design of novel therapeutic agents.
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Affiliation(s)
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology and Department of Cell Biology, New York University School of Medicine, New York, New York, United States
| | - Anke C Schiedel
- Pharmaceutical Chemistry I, PharmaCenter Bonn, University of Bonn, Bonn, Germany
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14
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Danish A, Namasivayam V, Schiedel AC, Müller CE. Interaction of Approved Drugs with Synaptic Vesicle Protein 2A. Arch Pharm (Weinheim) 2017; 350. [PMID: 28220535 DOI: 10.1002/ardp.201700003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/04/2017] [Accepted: 02/05/2017] [Indexed: 11/09/2022]
Abstract
Levetiracetam (LEV) and its recently approved derivative brivaracetam are anti-epileptic drugs with a unique mechanism of action. The synaptic vesicle protein 2A (SV2A) was previously identified as their main target. In the current study, we tested a collection of 500 approved drugs for interaction with the human SV2A protein expressed in Chinese hamster ovary cells. Competition binding studies were performed using cell lysates with high SV2A expression and [3 H]brivaracetam as a radioligand. A hit rate of 3% was obtained, defined as compounds that inhibited radioligand binding by more than 90% at a screening concentration of 20 μM. Subsequent concentration-inhibition curves revealed the antihistaminic prodrug loratadine (Ki = 1.16 μM) and the antimalarial drug quinine (Ki = 2.03 μM) to be the most potent SV2A protein ligands of the investigated drug library. Both compounds were similarly potent as LEV (Ki = 1.74 μM), providing structurally novel scaffolds for SV2A ligands. A pharmacophore model was established, which indicated steric and electronic conformities of brivaracetam with the new SV2A ligands, and preliminary structure-activity relationships were determined. The anti-convulsive effects of the natural product quinine may - at least in part - be explained by interaction with SV2A. Loratadine and quinine represent new lead structures for anti-epileptic drug development.
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Affiliation(s)
- Azeem Danish
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Vigneshwaran Namasivayam
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
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15
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Abdelrahman A, Namasivayam V, Hinz S, Schiedel AC, Köse M, Burton M, El-Tayeb A, Gillard M, Bajorath J, de Ryck M, Müller CE. Characterization of P2X4 receptor agonists and antagonists by calcium influx and radioligand binding studies. Biochem Pharmacol 2017; 125:41-54. [DOI: 10.1016/j.bcp.2016.11.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 11/15/2016] [Indexed: 10/20/2022]
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16
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De Filippo E, Schiedel AC, Manga P. Interaction between G Protein-Coupled Receptor 143 and Tyrosinase: Implications for Understanding Ocular Albinism Type 1. J Invest Dermatol 2016; 137:457-465. [PMID: 27720922 DOI: 10.1016/j.jid.2016.09.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 09/26/2016] [Accepted: 09/27/2016] [Indexed: 12/31/2022]
Abstract
Developmental eye defects in X-linked ocular albinism type 1 are caused by G-protein coupled receptor 143 (GPR143) mutations. Mutations result in dysfunctional melanosome biogenesis and macromelanosome formation in pigment cells, including melanocytes and retinal pigment epithelium. GPR143, primarily expressed in pigment cells, localizes exclusively to endolysosomal and melanosomal membranes unlike most G protein-coupled receptors, which localize to the plasma membrane. There is some debate regarding GPR143 function and elucidating the role of this receptor may be instrumental for understanding neurogenesis during eye development and for devising therapies for ocular albinism type I. Many G protein-coupled receptors require association with other proteins to function. These G protein-coupled receptor-interacting proteins also facilitate fine-tuning of receptor activity and tissue specificity. We therefore investigated potential GPR143 interaction partners, with a focus on the melanogenic enzyme tyrosinase. GPR143 coimmunoprecipitated with tyrosinase, while confocal microscopy demonstrated colocalization of the proteins. Furthermore, tyrosinase localized to the plasma membrane when coexpressed with a GPR143 trafficking mutant. The physical interaction between the proteins was confirmed using fluorescence resonance energy transfer. This interaction may be required in order for GPR143 to function as a monitor of melanosome maturation. Identifying tyrosinase as a potential GPR143 binding protein opens new avenues for investigating the mechanisms that regulate pigmentation and neurogenesis.
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Affiliation(s)
| | - Anke C Schiedel
- Pharmaceutical Chemistry I, PharmaCenter Bonn, University of Bonn, Bonn, Germany.
| | - Prashiela Manga
- Ronald O. Perelman, Department of Dermatology, New York University School of Medicine, New York, New York, USA.
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17
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Köse M, Schiedel AC, Bauer AA, Poschenrieder H, Burbiel JC, Akkinepally RR, Stachel HD, Müller CE. Focused screening to identify new adenosine kinase inhibitors. Bioorg Med Chem 2016; 24:5127-5133. [PMID: 27595538 DOI: 10.1016/j.bmc.2016.08.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/10/2016] [Accepted: 08/18/2016] [Indexed: 01/18/2023]
Abstract
Adenosine kinase (AdK) is a key player in controlling intra- and extracellular concentrations of the signaling molecule adenosine. Extensive evidence points to an important role of AdK in several diseases, and suggests that AdK inhibition might be a promising therapeutic strategy. The development of a new AdK assay and subsequent screening of part of our focused compound library led to the identification of 12 hit compounds (hit rate of 6%) representing six new classes of non-nucleoside human AdK inhibitors. The most potent inhibitor 1 displayed a Ki value of 184nM. Compound screening with a newly developed assay was useful and efficient for discovering novel AdK inhibitors which may serve as lead structures for developing drugs for adenosine augmentation therapy.
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Affiliation(s)
- Meryem Köse
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany.
| | - Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Alexander Andreas Bauer
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Hermann Poschenrieder
- Department Pharmazie, Zentrum für Pharmaforschung, Universität München, Butenandtstr. 7, D-81377 München, Germany
| | - Joachim C Burbiel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Raghuram Rao Akkinepally
- University College of Pharmaceutical Sciences, Kakatiya University, Warangal, A.P. 506009, India
| | - Hans-Dietrich Stachel
- Department Pharmazie, Zentrum für Pharmaforschung, Universität München, Butenandtstr. 7, D-81377 München, Germany
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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18
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De Filippo E, Namasivayam V, Zappe L, El-Tayeb A, Schiedel AC, Müller CE. Role of extracellular cysteine residues in the adenosine A2A receptor. Purinergic Signal 2016; 12:313-29. [PMID: 26969588 DOI: 10.1007/s11302-016-9506-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 02/29/2016] [Indexed: 12/13/2022] Open
Abstract
The G protein-coupled A2A adenosine receptor represents an important drug target. Crystal structures and modeling studies indicated that three disulfide bonds are formed between ECL1 and ECL2 (I, Cys71(2.69)-Cys159(45.43); II, Cys74(3.22)-Cys146(45.30), and III, Cys77(3.25)-Cys166(45.50)). However, the A2BAR subtype appears to require only disulfide bond III for proper function. In this study, each of the three disulfide bonds in the A2AAR was disrupted by mutation of one of the cysteine residues to serine. The mutant receptors were stably expressed in Chinese hamster ovary cells and analyzed in cyclic adenosine monophosphate (cAMP) accumulation and radioligand binding studies using structurally diverse agonists: adenosine, NECA, CGS21680, and PSB-15826. Results were rationalized by molecular modeling. The observed effects were dependent on the investigated agonist. Loss of disulfide bond I led to a widening of the orthosteric binding pocket resulting in a strong reduction in the potency of adenosine, but not of NECA or 2-substituted nucleosides. Disruption of disulfide bond II led to a significant reduction in the agonists' efficacy indicating its importance for receptor activation. Disulfide bond III disruption reduced potency and affinity of the small adenosine agonists and NECA, but not of the larger 2-substituted agonists. While all the three disulfide bonds were essential for high potency or efficacy of adenosine, structural modification of the nucleoside could rescue affinity or efficacy at the mutant receptors. At present, it cannot be excluded that formation of the extracellular disulfide bonds in the A2AAR is dynamic. This might add another level of G protein-coupled receptor (GPCR) modulation, in particular for the cysteine-rich A2A and A2BARs.
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Affiliation(s)
- Elisabetta De Filippo
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Vigneshwaran Namasivayam
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Lukas Zappe
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Ali El-Tayeb
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Anke C Schiedel
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Christa E Müller
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany.
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19
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Alnouri MW, Jepards S, Casari A, Schiedel AC, Hinz S, Müller CE. Selectivity is species-dependent: Characterization of standard agonists and antagonists at human, rat, and mouse adenosine receptors. Purinergic Signal 2015; 11:389-407. [PMID: 26126429 PMCID: PMC4529847 DOI: 10.1007/s11302-015-9460-9] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 06/17/2015] [Indexed: 12/14/2022] Open
Abstract
Adenosine receptors (ARs) have emerged as new drug targets. The majority of data on affinity/potency and selectivity of AR ligands described in the literature has been obtained for the human species. However, preclinical studies are mostly performed in mouse or rat, and standard AR agonists and antagonists are frequently used for studies in rodents without knowing their selectivity in the investigated species. In the present study, we selected a set of frequently used standard AR ligands, 8 agonists and 16 antagonists, and investigated them in radioligand binding studies at all four AR subtypes, A1, A2A, A2B, and A3, of three species, human, rat, and mouse. Recommended, selective agonists include CCPA (for A1AR of rat and mouse), CGS-21680 (for A2A AR of rat), and Cl-IB-MECA (for A3AR of all three species). The functionally selective partial A2B agonist BAY60-6583 was found to additionally bind to A1 and A3AR and act as an antagonist at both receptor subtypes. The antagonists PSB-36 (A1), preladenant (A2A), and PSB-603 (A2B) displayed high selectivity in all three investigated species. MRS-1523 acts as a selective A3AR antagonist in human and rat, but is only moderately selective in mouse. The comprehensive data presented herein provide a solid basis for selecting suitable AR ligands for biological studies.
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MESH Headings
- Adenosine A1 Receptor Agonists/metabolism
- Adenosine A1 Receptor Agonists/pharmacology
- Adenosine A1 Receptor Antagonists/metabolism
- Adenosine A1 Receptor Antagonists/pharmacology
- Adenosine A2 Receptor Agonists/metabolism
- Adenosine A2 Receptor Agonists/pharmacology
- Adenosine A2 Receptor Antagonists/metabolism
- Adenosine A2 Receptor Antagonists/pharmacology
- Adenosine A3 Receptor Agonists/metabolism
- Adenosine A3 Receptor Agonists/pharmacology
- Adenosine A3 Receptor Antagonists/metabolism
- Adenosine A3 Receptor Antagonists/pharmacology
- Animals
- Arrestin/metabolism
- Binding, Competitive/drug effects
- CHO Cells
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cricetinae
- Cricetulus
- Cyclic AMP/metabolism
- DNA, Complementary/drug effects
- DNA, Complementary/genetics
- Humans
- Mice
- Rats
- Receptor, Adenosine A2A/drug effects
- Receptor, Adenosine A2A/genetics
- Receptor, Adenosine A2A/metabolism
- Receptor, Adenosine A2B/drug effects
- Receptor, Adenosine A2B/genetics
- Receptor, Adenosine A2B/metabolism
- Receptors, Purinergic P1/drug effects
- Receptors, Purinergic P1/genetics
- Receptors, Purinergic P1/metabolism
- Species Specificity
- Structure-Activity Relationship
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Affiliation(s)
- Mohamad Wessam Alnouri
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Stephan Jepards
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Alessandro Casari
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Anke C. Schiedel
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Sonja Hinz
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Christa E. Müller
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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Knospe M, Müller CE, Rosa P, Abdelrahman A, von Kügelgen I, Thimm D, Schiedel AC. The rat adenine receptor: pharmacological characterization and mutagenesis studies to investigate its putative ligand binding site. Purinergic Signal 2013; 9:367-81. [PMID: 23413038 PMCID: PMC3757150 DOI: 10.1007/s11302-013-9355-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 01/23/2013] [Indexed: 12/20/2022] Open
Abstract
The rat adenine receptor (rAdeR) was the first member of a family of G protein-coupled receptors (GPCRs) activated by adenine and designated as P0-purine receptors. The present study aimed at gaining insights into structural aspects of ligand binding and function of the rAdeR. We exchanged amino acid residues predicted to be involved in ligand binding (Phe110(3.24), Asn115(3.29), Asn173(4.60), Phe179(45.39), Asn194(5.40), Phe195(5.41), Leu201(5.47), His252(6.54), and Tyr268(7.32)) for alanine and expressed them in Spodoptera frugiperda (Sf9) insect cells. Membrane preparations subjected to [(3)H]adenine binding studies revealed only minor effects indicating that none of the exchanged amino acids is part of the ligand binding pocket, at least in the inactive state of the receptor. Furthermore, we coexpressed the rAdeR and its mutants with mammalian Gi proteins in Sf9 insect cells to probe receptor activation. Two amino acid residues, Asn194(5.40) and Leu201(5.47), were found to be crucial for activation since their alanine mutants did not respond to adenine. Moreover we showed that-in contrast to most other rhodopsin-like GPCRs-the rAdeR does not contain essential disulfide bonds since preincubation with dithiothreitol neither altered adenine binding in Sf9 cell membranes, nor adenine-induced inhibition of adenylate cyclase in 1321N1 astrocytoma cells transfected with the rAdeR. To detect rAdeRs by Western blot analysis, we developed a specific antibody. Finally, we were able to show that the extended N-terminal sequence of the rAdeR constitutes a putative signal peptide of unknown function that is cleaved off in the mature receptor. Our results provide important insights into this new, poorly investigated family of purinergic receptors.
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Affiliation(s)
- Melanie Knospe
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Christa E. Müller
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Patrizia Rosa
- />CNR—Institute of Neuroscience and Department of Medical Biotechnologies and Translational Medicine (BIOMETRA), University of Milan, Milan, Italy
| | - Aliaa Abdelrahman
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Ivar von Kügelgen
- />PharmaCenter Bonn, Department of Pharmacology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany
| | - Dominik Thimm
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Anke C. Schiedel
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
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Thimm D, Knospe M, Abdelrahman A, Moutinho M, Alsdorf BBA, von Kügelgen I, Schiedel AC, Müller CE. Characterization of new G protein-coupled adenine receptors in mouse and hamster. Purinergic Signal 2013; 9:415-26. [PMID: 23608776 PMCID: PMC3757137 DOI: 10.1007/s11302-013-9360-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/26/2013] [Indexed: 10/26/2022] Open
Abstract
The nucleobase adenine has previously been reported to activate G protein-coupled receptors in rat and mouse. Adenine receptors (AdeR) thus constitute a new family of purine receptors, for which the designation "P0-receptors" has been suggested. We now describe the cloning and characterization of two new members of the AdeR family from mouse (MrgA10, termed mAde1R) and hamster (cAdeR). Both receptors were expressed in Sf9 insect cells, and radioligand binding studies were performed using [(3)H]adenine. Specific binding of the radioligand was detected in transfected, but not in untransfected cells, and K D values of 286 nM (mAde1R, B max 1.18 pmol/mg protein) and 301 nM (cAdeR, B max 17.7 pmol/mg protein), respectively, were determined. A series of adenine derivatives was investigated in competition binding assays. Minor structural modifications generally led to a reduction or loss of affinity, with one exception: 2-fluoroadenine was at least as potent as adenine itself at the cAdeR. Structure-activity relationships at all AdeR orthologs and subtypes investigated so far were similar, but not identical. For functional analyses, the cAdeR was homologously expressed in Chinese hamster ovary (CHO) cells, while the mAde1R was heterologously expressed in 1321N1 astrocytoma cells. Like the previously described AdeRs from rat (rAdeR) and mouse (mAde2R), the mAde1R (EC50 9.77 nM) and the cAdeR (EC50 51.6 nM) were coupled to inhibition of adenylate cyclase. In addition, the cAdeR from hamster expressed in CHO cells produced an increase in intracellular calcium concentrations (EC50 6.24 nM) and was found to be additionally coupled to Gq proteins.
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Affiliation(s)
- Dominik Thimm
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Melanie Knospe
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Aliaa Abdelrahman
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Miguel Moutinho
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Bernt B. A. Alsdorf
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Ivar von Kügelgen
- />PharmaCenter Bonn, Department of Pharmacology, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany
| | - Anke C. Schiedel
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Christa E. Müller
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
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Schiedel AC, Lacher SK, Linnemann C, Knolle PA, Müller CE. Antiproliferative effects of selective adenosine receptor agonists and antagonists on human lymphocytes: evidence for receptor-independent mechanisms. Purinergic Signal 2013; 9:351-65. [PMID: 23359122 PMCID: PMC3757146 DOI: 10.1007/s11302-013-9354-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 01/16/2013] [Indexed: 01/05/2023] Open
Abstract
The effects of standard adenosine receptor (AR) agonists and antagonists on the proliferation of human T lymphocytes, unstimulated and phytohemagglutinin-stimulated human peripheral blood lymphocytes (PBL), and Jurkat T cells were investigated. Real-time PCR measurements confirmed the presence of all four AR subtypes on the investigated cells, although at different expression levels. A2A ARs were predominantly expressed in PBL and further upregulated upon stimulation, while malignant Jurkat T cells showed high expression levels of A1, A2A, and A2B ARs. Cell proliferation was measured by [(3)H]-thymidine incorporation assays. Several ligands, including the subtype-selective agonists CPA (A1), BAY60-6583 (A2B), and IB-MECA (A3), and the antagonists PSB-36 (A1), MSX-2 (A2A), and PSB-10 (A3) significantly inhibited cell proliferation at micromolar concentrations, which were about three orders of magnitude higher than their AR affinities. In contrast, further investigated AR ligands, including the agonists NECA (nonselective) and CGS21680 (A2A), and the antagonists preladenant (SCH-420814, A2A), PSB-1115 (A2B), and PSB-603 (A2B) showed no or only minor effects on lymphocyte proliferation. The anti-proliferative effects of the AR agonists could not be blocked by the corresponding antagonists. The non-selective AR antagonist caffeine stimulated phytohemagglutinin-activated PBL with an EC50 value of 104 μM. This is the first study to compare a complete set of commonly used AR ligands for all subtypes on lymphocyte proliferation. Our results strongly suggest that these compounds induce an inhibition of lymphocyte proliferation and cell death through AR-independent mechanisms.
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Affiliation(s)
- Anke C. Schiedel
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Sciences Bonn (PSB), Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Svenja K. Lacher
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Sciences Bonn (PSB), Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Carsten Linnemann
- />Institute of Molecular Medicine and Experimental Immunology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Percy A. Knolle
- />Institute of Molecular Medicine and Experimental Immunology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Christa E. Müller
- />PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Sciences Bonn (PSB), Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
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Kishore BK, Zhang Y, Gevorgyan H, Kohan DE, Schiedel AC, Müller CE, Peti-Peterdi J. Cellular localization of adenine receptors in the rat kidney and their functional significance in the inner medullary collecting duct. Am J Physiol Renal Physiol 2013; 305:F1298-305. [PMID: 23986514 DOI: 10.1152/ajprenal.00254.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Gi-coupled adenine receptor (AdeR) binds adenine with high affinity and potentially reduces cellular cAMP levels. Since cAMP is an important second messenger in the renal transport of water and solutes, we localized AdeR in the rat kidney. Real-time RT-PCR showed higher relative expression of AdeR mRNA in the cortex and outer medulla compared with the inner medulla. Immunoblots using a peptide-derived and affinity-purified rabbit polyclonal antibody specific for an 18-amino acid COOH-terminal sequence of rat AdeR, which we generated, detected two bands between ∼30 and 40 kDa (molecular mass of native protein: 37 kDa) in the cortex, outer medulla, and inner medulla. These bands were ablated by preadsorption of the antibody with the immunizing peptide. Immunofluorescence labeling showed expression of AdeR protein in all regions of the kidney. Immunoperoxidase revealed strong labeling of AdeR protein in the cortical vasculature, including the glomerular arterioles, and less intense labeling in the cells of the collecting duct system. Confocal immunofluorescence imaging colocalized AdeR with aquaporin-2 protein to the apical plasma membrane in the collecting duct. Functionally, adenine (10 μM) significantly decreased (P < 0.01) 1-deamino-8-d-arginine vasopressin (10 nM)-induced cAMP production in ex vivo preparations of inner medullary collecting ducts, which was reversed by PSB-08162 (20 μM, P < 0.01), a selective antagonist of AdeR. Thus, we demonstrated the expression of AdeR in the renal vasculature and collecting ducts and its functional relevance. This study may open a new avenue for the exploration of autocrine/paracrine regulation of renal vascular and tubular functions by the nucleobase adenine in health and disease.
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Affiliation(s)
- Bellamkonda K Kishore
- Nephrology Research (151M Veterans Affairs Salt Lake City Health Care System, 500 Foothill Drive, Salt Lake City, UT 84148.
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Funke M, Thimm D, Schiedel AC, Müller CE. 8-Benzamidochromen-4-one-2-carboxylic acids: potent and selective agonists for the orphan G protein-coupled receptor GPR35. J Med Chem 2013; 56:5182-97. [PMID: 23713606 DOI: 10.1021/jm400587g] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
8-Amido-chromen-4-one-2-carboxylic acid derivatives were identified as novel agonists at the G protein-coupled orphan receptor GPR35. They were characterized by a β-arrestin recruitment assay and optimized to obtain agonists with nanomolar potency for the human GPR35. The compounds were found to exhibit high selectivity versus the related GPR55. The most potent agonists were 6-bromo-8-(4-methoxybenzamido)-4-oxo-4H-chromene-2-carboxylic acid (85, EC50 12.1 nM) and 6-bromo-8-(2-chloro-4-methoxybenzamido)-4-oxo-4H-chromene-2-carboxylic acid (90, EC50 11.1 nM), both of which were >1700-fold selective versus GPR55. Most compounds were considerably less potent at rat and mouse than at human GPR35. 6-Bromo-8-(2-methoxybenzamido)-4-oxo-4H-chromene-2-carboxylic acid (87) was the only derivative that activated GPR35 of all three species at similar, low micromolar concentration. Compounds 85 and 90 are the most potent agonists at the human GPR35 known to date and might thus serve as powerful pharmacological tools to further elucidate the receptor's (patho)physiological role and its potential as a future drug target.
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Affiliation(s)
- Mario Funke
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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Seibt BF, Schiedel AC, Thimm D, Hinz S, Sherbiny FF, Müller CE. The second extracellular loop of GPCRs determines subtype-selectivity and controls efficacy as evidenced by loop exchange study at A2 adenosine receptors. Biochem Pharmacol 2013; 85:1317-29. [PMID: 23500543 DOI: 10.1016/j.bcp.2013.03.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 01/19/2023]
Abstract
The second extracellular loop (EL2) of G protein-coupled receptors (GPCRs), which represent important drug targets, may be involved in ligand recognition and receptor activation. We studied the closely related adenosine receptor (AR) subtypes A2A and A2B by exchanging the complete EL2 of the human A2BAR for the EL2 of the A2AAR. Furthermore, single amino acid residues (Asp148(45.27), Ser149(45.28), Thr151(45.30), Glu164(45.43), Ser165(45.44), and Val169(45.48)) in the EL2 of the A2BAR were exchanged for alanine. The single mutations did not lead to any major effects, except for the T151A mutant, at which NECA showed considerably increased efficacy. The loop exchange entailed significant effects: The A2A-selective agonist CGS21680, while being completely inactive at A2BARs, showed high affinity for the mutant A2B(EL2-A2A)AR, and was able to fully activate the receptor. Most strikingly, all agonists investigated (adenosine, NECA, BAY60-6583, CGS21680) showed strongly increased efficacies at the mutant A2B(EL2-A2A) as compared to the wt AR. Thus, the EL2 of the A2BAR appears to have multiple functions: besides its involvement in ligand binding and subtype selectivity it modulates agonist-bound receptor conformations thereby controlling signalling efficacy. This role of the EL2 is likely to extend to other members of the GPCR family, and the EL2 of GPCRs appears to be an attractive target structure for drugs.
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Affiliation(s)
- Benjamin F Seibt
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, 53121 Bonn, Germany
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Thimm D, Schiedel AC, Sherbiny FF, Hinz S, Hochheiser K, Bertarelli DCG, Maass A, Müller CE. Ligand-specific binding and activation of the human adenosine A(2B) receptor. Biochemistry 2013; 52:726-40. [PMID: 23286920 DOI: 10.1021/bi3012065] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Adenosine A(2B) receptors, which play a role in inflammation and cancer, are of considerable interest as novel drug targets. To gain deeper insights into ligand binding and receptor activation, we exchanged amino acids predicted to be close to the binding pocket. The alanine mutants were stably expressed in CHO cells and characterized by radioligand binding and cAMP assays using three structural classes of ligands: xanthine (antagonist), adenosine, and aminopyridine derivatives (agonists). Asn282(7.45) and His280(7.43) were found to stabilize the binding site by intramolecular hydrogen bond formation as in the related A(2A) receptor subtype. Trp247(6.48), Val250(6.51), and particularly Ser279(7.42) were shown to be important for binding of nucleosidic agonists. Leu81(3.28), Asn186(5.42), and Val250(6.51) were discovered to be crucial for binding of the xanthine-derived antagonist PSB-603. Leu81(3.28), which is not conserved among adenosine receptor subtypes, may be important for the high selectivity of PSB-603. The N186(5.42)A mutant resulted in an increased potency for agonists. The interactions of the non-nucleosidic agonist BAY60-6583 were different from those of the nucleosides: while BAY60-6583 appeared not to interact with Ser279(7.42), its interactions with Trp247(6.48) and Val250(6.51) were significantly weaker compared to those of NECA. Moreover, our results discount the hypothesis of Trp247(6.48) serving as a "toogle switch" because BAY60-6583 was able to activate the corresponding mutant. This study reveals distinct interactions of structurally diverse ligands with the human A(2B) receptor and differences between closely related receptor subtypes (A(2B) and A(2A)). It will contribute to the understanding of G protein-coupled receptor function and advance A(2B) receptor ligand design.
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Affiliation(s)
- Dominik Thimm
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, 53121 Bonn, Germany
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Schiedel AC, Hinz S, Thimm D, Sherbiny F, Borrmann T, Maass A, Müller CE. The four cysteine residues in the second extracellular loop of the human adenosine A2B receptor: role in ligand binding and receptor function. Biochem Pharmacol 2011; 82:389-99. [PMID: 21620804 DOI: 10.1016/j.bcp.2011.05.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/09/2011] [Accepted: 05/11/2011] [Indexed: 11/17/2022]
Abstract
The adenosine A(2B) receptor is of considerable interest as a new drug target for the treatment of asthma, inflammatory diseases, pain, and cancer. In the present study we investigated the role of the cysteine residues in the extracellular loop 2 (ECL2) of the receptor, which is particularly cysteine-rich, by a combination of mutagenesis, molecular modeling, chemical and pharmacological experiments. Pretreatment of CHO cells recombinantly expressing the human A(2B) receptor with dithiothreitol led to a 74-fold increase in the EC(50) value of the agonist NECA in cyclic AMP accumulation. In the C78(3.25)S and the C171(45.50)S mutant high-affinity binding of the A(2B) antagonist radioligand [(3)H]PSB-603 was abolished and agonists were virtually inactive in cAMP assays. This indicates that the C3.25-C45.50 disulfide bond, which is highly conserved in GPCRs, is also important for binding and function of A(2B) receptors. In contrast, the C166(45.45)S and the C167(45.46)S mutant as well as the C166(45.45)S-C167(45.46)S double mutant behaved like the wild-type receptor, while in the C154(45.33)S mutant significant, although more subtle effects on cAMP accumulation were observed - decrease (BAY60-6583) or increase (NECA) - depending on the structure of the investigated agonist. In contrast to the X-ray structure of the closely related A(2A) receptor, which showed four disulfide bonds, the present data indicate that in the A(2B) receptor only the C3.25-C45.50 disulfide bond is essential for ligand binding and receptor activation. Thus, the cysteine residues in the ECL2 of the A(2B) receptor not involved in stabilization of the receptor structure may have other functions.
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Affiliation(s)
- Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany.
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Cadet M, Gomez I, Schiedel AC, Oeljeklaus S, Dyer JH. Investigation of Mutations of Sunflower Cotyledon Acetoacetyl CoA Thiolase. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.896.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Melissa Cadet
- Chemistry and BiochemistryMontclair State UniversityMontclairNJ
| | - Iris Gomez
- Chemistry and BiochemistryMontclair State UniversityMontclairNJ
| | | | - Silke Oeljeklaus
- Medizinisches Proteom‐CenterRuhr‐Universtität BochumBochumGermany
| | - James H. Dyer
- Chemistry and BiochemistryMontclair State UniversityMontclairNJ
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Gomez I, Cadet M, Oeljeklaus S, Schiedel AC, Dyer JH. Expression and Purification of Sunflower Cotyledon Acetoacetyl CoA Thiolase Mutants. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.896.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Iris Gomez
- Chemistry and BiochemistryMontclair State UniversityMontclairNJ
| | - Melissa Cadet
- Chemistry and BiochemistryMontclair State UniversityMontclairNJ
| | - Silke Oeljeklaus
- Medizinisches Proteom‐CenterRuhr‐Universtität BochumBochumGermany
| | | | - James H. Dyer
- Chemistry and BiochemistryMontclair State UniversityMontclairNJ
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Dyer JH, Maina A, Gomez ID, Cadet M, Oeljeklaus S, Schiedel AC. Cloning, expression and purification of an acetoacetyl CoA thiolase from sunflower cotyledon. Int J Biol Sci 2009; 5:736-44. [PMID: 20011134 PMCID: PMC2793306 DOI: 10.7150/ijbs.5.736] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 11/24/2009] [Indexed: 12/14/2022] Open
Abstract
Thiolase I and II coexist as part of the glyoxysomal beta-oxidation system in sunflower (Helianthus annuus L.) cotyledons, the only system shown to have both forms. The importance of thiolases can be underscored not only by their ubiquity, but also by their involvement in a wide variety of processes in plants, animals and bacteria. Here we describe the cloning, expression and purification of acetoacetyl CoA thiolase (AACT) in enzymatically active form. Use of the extensive amount of sequence information from the databases facilitated the efficient generation of the gene-specific primers used in the RACE protocols. The recombinant AACT (1233 bp) shares 75% similarity with other plant AACTs. Comparison of specific activity of this recombinant AACT to a previously reported enzyme purified from primary sunflower cotyledon tissue was very similar (263 nkat/mg protein vs 220 nkat/mg protein, respectively). Combining the most pure fractions from the affinity column, the enzyme was purified 88-fold with a 55% yield of the enzymatically active, 47 kDa AACT.
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Affiliation(s)
- James H Dyer
- Department of Chemistry and Biochemistry, Montclair State University, NJ 07043, USA.
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31
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Borrmann T, Abdelrahman A, Volpini R, Lambertucci C, Alksnis E, Gorzalka S, Knospe M, Schiedel AC, Cristalli G, Müller CE. Structure−Activity Relationships of Adenine and Deazaadenine Derivatives as Ligands for Adenine Receptors, a New Purinergic Receptor Family. J Med Chem 2009; 52:5974-89. [DOI: 10.1021/jm9006356] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas Borrmann
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Aliaa Abdelrahman
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Rosaria Volpini
- Dipartimento di Scienze Chimiche, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Catia Lambertucci
- Dipartimento di Scienze Chimiche, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Edgars Alksnis
- Latvian Institute of Organic Synthesis, Aizkraukles iela 21, Riga LV-1006, Latvia
| | - Simone Gorzalka
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Melanie Knospe
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Anke C. Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Gloria Cristalli
- Dipartimento di Scienze Chimiche, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Christa E. Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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von Kügelgen I, Schiedel AC, Hoffmann K, Alsdorf BBA, Abdelrahman A, Müller CE. Cloning and Functional Expression of a Novel GiProtein-Coupled Receptor for Adenine from Mouse Brain. Mol Pharmacol 2007; 73:469-77. [DOI: 10.1124/mol.107.037069] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Schiedel AC, Meyer H, Alsdorf BBA, Gorzalka S, Brüssel H, Müller CE. [(3)H]Adenine is a suitable radioligand for the labeling of G protein-coupled adenine receptors but shows high affinity to bacterial contaminations in buffer solutions. Purinergic Signal 2007; 3:347-58. [PMID: 18404448 PMCID: PMC2072912 DOI: 10.1007/s11302-007-9060-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2007] [Accepted: 06/25/2007] [Indexed: 12/18/2022] Open
Abstract
[3H]Adenine has previously been used to label the newly discovered G protein-coupled murine adenine receptors. Recent reports have questioned the suitability of [3H]adenine for adenine receptor binding studies because of curious results, e.g. high specific binding even in the absence of mammalian protein. In this study, we showed that specific [3H]adenine binding to various mammalian membrane preparations increased linearly with protein concentration. Furthermore, we found that Tris-buffer solutions typically used for radioligand binding studies (50 mM, pH 7.4) that have not been freshly prepared but stored at 4°C for some time may contain bacterial contaminations that exhibit high affinity binding for [3H]adenine. Specific binding is abolished by heating the contaminated buffer or filtering it through 0.2-μm filters. Three different, aerobic, gram-negative bacteria were isolated from a contaminated buffer solution and identified as Achromobacter xylosoxidans, A. denitrificans, and Acinetobacter lwoffii. A. xylosoxidans, a common bacterium that can cause nosocomial infections, showed a particularly high affinity for [3H]adenine in the low nanomolar range. Structure–activity relationships revealed that hypoxanthine also bound with high affinity to A. xylosoxidans, whereas other nucleobases (uracil, xanthine) and nucleosides (adenosine, uridine) did not. The nature of the labeled site in bacteria is not known, but preliminary results indicate that it may be a high-affinity purine transporter. We conclude that [3H]adenine is a well-suitable radioligand for adenine receptor binding studies but that bacterial contamination of the employed buffer solutions must be avoided.
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Affiliation(s)
- Anke C Schiedel
- University of Bonn, Pharmaceutical Institute, Pharmaceutical Sciences Bonn (PSB), Pharmaceutical Chemistry I, Bonn, Germany
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Schiedel AC, Oeljeklaus S, Minihan P, Dyer JH. Cloning, expression, and purification of glyoxysomal 3-oxoacyl-CoA thiolase from sunflower cotyledons. Protein Expr Purif 2004; 33:25-33. [PMID: 14680958 DOI: 10.1016/j.pep.2003.08.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Indexed: 11/16/2022]
Abstract
The glyoxysomal beta-oxidation system in sunflower (Helianthus annuus L.) cotyledons is distinguished by the coexistence of two different thiolase isoforms, thiolase I and II. So far, this phenomenon has only been described for glyoxysomes from sunflower cotyledons. Thiolase I (acetoacetyl-CoA thiolase, EC 2.3.1.9) recognizes acetoacetyl-CoA only, while thiolase II (3-oxoacyl-CoA thiolase, EC 2.3.1.16) exhibits a more broad substrate specificity towards 3-oxoacyl-CoA esters of different chain length. Here, we report on the cloning of thiolase II from sunflower cotyledons. The known DNA sequence of Cucumis sativus 3-oxoacyl-CoA thiolase was used to generate primers for cloning the corresponding thiolase from sunflower cotyledons. RT-PCR was then used to generate an internal fragment of the sunflower thiolase gene and the termini were isolated using 5'- and 3'-RACE. Full-length cDNA was generated using RT-PCR with sunflower thiolase-specific primers flanking the coding region. The resultant gene encodes a thiolase sharing at least 80% identity with other plant thiolases at the amino acid level. The recombinant sunflower thiolase II was expressed in a bacterial system in an active form and purified to apparent homogeneity in a single step using Ni-NTA agarose chromatography. The enzyme was purified 53.4-fold and had a specific activity of 235 nkat/mg protein. Pooled fractions from the Ni-NTA column resulted in an 83% yield of active enzyme to be used for further characterization.
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Affiliation(s)
- Anke C Schiedel
- Cell Biology, MSB, New York University Medical Center, New York, NY 10016, USA
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Mayer T, Meyer M, Janning A, Schiedel AC, Barnekow A. A mutant form of the rho protein can restore stress fibers and adhesion plaques in v-src transformed fibroblasts. Oncogene 1999; 18:2117-28. [PMID: 10321736 DOI: 10.1038/sj.onc.1202537] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The organization of polymerized actin in the mammalian cell is regulated by several members of the rho family. Three rho proteins, cdc42, rac and rho act in a cascade to organize the intracellular actin cytoskeleton. Rho proteins are involved in the formation of actin stress fibers and adhesion plaques in fibroblasts. During transformation of mammalian cells by oncogenes the cytoskeleton is rearranged and stress fibers and adhesion plaques are disintegrated. In this paper we investigate the function of the rho protein in RR1022 rat fibroblasts transformed by the Rous sarcoma virus. Two activated mutants of the rho protein, rho G14V and rho Q63L, and a dominant negative mutant, rho N1171, were stably transfected into RR1022 cells. The resulting cell lines were analysed for the organization of polymerized actin and adhesion plaques. Cells expressing rho Q63L, but not rho wt, rho G14V or rho N1171, showed an altered morphology. These cells displayed a flat, fibroblast like shape when compared with the RR1022 ancestor cells. Immunofluorescence analyses revealed that actin stress fibers and adhesion plaques were rearranged in these cells. We conclude from these data that an active rho protein can restore elements of the actin cytoskeleton in transformed cells by overriding the tyrosine kinase phosphorylation induced by the pp60(v-src).
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Affiliation(s)
- T Mayer
- Department for Experimental Tumorbiology, Muenster University, Germany
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Schiedel AC, Barnekow A, Mayer T. Nucleotide induced conformation determines posttranslational isoprenylation of the ras related rab6 protein in insect cells. FEBS Lett 1995; 376:113-9. [PMID: 8521955 DOI: 10.1016/0014-5793(95)01258-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Small GTP binding proteins of the rab/YPT family are essential regulators of vectorial transport in the eukaryotic cell. Members of the rab/YPT1 family are found on the cytoplasmic surface of distinct intracellular membrane compartments. Membrane attachment is facilitated by a C-terminal geranylgeranyl moiety. In this report we investigated posttranslational modification and membrane binding of the rab6 protein, a member of the rab/YPT family located on the Golgi apparatus. A set of point mutations, which simulate the GDP or GTP bound conformation, was introduced into the rab6 cDNA. The mutated cDNAs were expressed in insect cells and the ability of the protein products to undergo geranylgeranyl modification and membrane association was assessed by Triton X-114 partition and cell fractionation. We report here that the modification of rab6 in insect cells depends on protein conformation. Only the GDP bound form, but not the GTP bound form is isoprenylated and subsequently membrane bound.
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Affiliation(s)
- A C Schiedel
- Department for Experimental Tumorbiology, Muenster University, Germany
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