1
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Gleixner J, Gattor AO, Humphrys LJ, Brunner T, Keller M. [ 3H]UR-JG102-A Radiolabeled Cyclic Peptide with High Affinity and Excellent Selectivity for the Neuropeptide Y Y 4 Receptor. J Med Chem 2023; 66:13788-13808. [PMID: 37773891 DOI: 10.1021/acs.jmedchem.3c01224] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
The family of human neuropeptide Y receptors (YRs) comprises four subtypes (Y1R, Y2R, Y4R, and Y5R) that are involved in the regulation of numerous physiological processes. Until now, Y4R binding studies have been predominantly performed in hypotonic sodium-free buffers using 125I-labeled derivatives of the endogenous YR agonists pancreatic polypeptide or peptide YY. A few tritium-labeled Y4R ligands have been reported; however, when used in buffers containing sodium at a physiological concentration, their Y4R affinities are insufficient. Based on the cyclic hexapeptide UR-AK86C, we developed a new tritium-labeled Y4R radioligand ([3H]UR-JG102, [3H]20). In sodium-free buffer, [3H]20 exhibits a very low Y4R dissociation constant (Kd 0.012 nM). In sodium-containing buffer (137 mM Na+), the Y4R affinity is lower (Kd 0.11 nM) but still considerably higher compared to previously reported tritiated Y4R ligands. Therefore, [3H]20 represents a useful tool compound for the determination of Y4R binding affinities under physiological-like conditions.
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Affiliation(s)
- Jakob Gleixner
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Albert O Gattor
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Laura J Humphrys
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Thomas Brunner
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Max Keller
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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2
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Müller C, Gleixner J, Tahk MJ, Kopanchuk S, Laasfeld T, Weinhart M, Schollmeyer D, Betschart MU, Lüdeke S, Koch P, Rinken A, Keller M. Structure-Based Design of High-Affinity Fluorescent Probes for the Neuropeptide Y Y 1 Receptor. J Med Chem 2022; 65:4832-4853. [PMID: 35263541 DOI: 10.1021/acs.jmedchem.1c02033] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The recent crystallization of the neuropeptide Y Y1 receptor (Y1R) in complex with the argininamide-type Y1R selective antagonist UR-MK299 (2) opened up a new approach toward structure-based design of nonpeptidic Y1R ligands. We designed novel fluorescent probes showing excellent Y1R selectivity and, in contrast to previously described fluorescent Y1R ligands, considerably higher (∼100-fold) binding affinity. This was achieved through the attachment of different fluorescent dyes to the diphenylacetyl moiety in 2 via an amine-functionalized linker. The fluorescent ligands exhibited picomolar Y1R binding affinities (pKi values of 9.36-9.95) and proved to be Y1R antagonists, as validated in a Fura-2 calcium assay. The versatile applicability of the probes as tool compounds was demonstrated by flow cytometry- and fluorescence anisotropy-based Y1R binding studies (saturation and competition binding and association and dissociation kinetics) as well as by widefield and total internal reflection fluorescence (TIRF) microscopy of live tumor cells, revealing that fluorescence was mainly localized at the plasma membrane.
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Affiliation(s)
- Christoph Müller
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jakob Gleixner
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Maris-Johanna Tahk
- Institute of Chemistry, Faculty of Bioorganic Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Sergei Kopanchuk
- Institute of Chemistry, Faculty of Bioorganic Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Tõnis Laasfeld
- Institute of Chemistry, Faculty of Bioorganic Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Michael Weinhart
- Institute of Inorganic Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Dieter Schollmeyer
- Department of Chemistry, Johannes-Gutenberg-University Mainz, Düsbergweg 10-14, 55099 Mainz, Germany
| | - Martin U Betschart
- Institute of Pharmaceutical Sciences, University of Freiburg, Albertstrasse 25, 79104 Freiburg, Germany
| | - Steffen Lüdeke
- Institute of Pharmaceutical Sciences, University of Freiburg, Albertstrasse 25, 79104 Freiburg, Germany
| | - Pierre Koch
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Ago Rinken
- Institute of Chemistry, Faculty of Bioorganic Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Max Keller
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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3
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Gruber CG, Pegoli A, Müller C, Grätz L, She X, Keller M. Differently fluorescence-labelled dibenzodiazepinone-type muscarinic acetylcholine receptor ligands with high M 2R affinity. RSC Med Chem 2020; 11:823-832. [PMID: 33479678 PMCID: PMC7650007 DOI: 10.1039/d0md00137f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 05/20/2020] [Indexed: 11/21/2022] Open
Abstract
A series of fluorescent dibenzodiazepinone-type muscarinic acetylcholine M2 receptor (M2R) ligands was synthesized using various fluorescent dyes (5-TAMRA, λ ex/λ em ≈ 547/576 nm; BODIPY 630/650, λ ex/λ em ≈ 625/640 nm; pyridinium dye Py-1, λ ex/λ em ≈ 611/665 nm and pyridinium dye Py-5, λ ex/λ em ≈ 465/732 nm). All fluorescent probes exhibited high M2R affinity (pK i (radioligand competition binding): 8.75-9.62, pK d (flow cytometry): 8.36-9.19), a very low preference for the M2R over the M1 and M4 receptors and moderate to pronounced M2R selectivity compared to the M3 and M5 receptors. The presented fluorescent ligands are considered useful molecular tools for future studies using methods such as fluorescence anisotropy and BRET based MR binding assays.
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Affiliation(s)
- Corinna G Gruber
- Institute of Pharmacy , Faculty of Chemistry and Pharmacy , University of Regensburg , Universitätsstrasse 31 , D-93053 Regensburg , Germany .
| | - Andrea Pegoli
- Institute of Pharmacy , Faculty of Chemistry and Pharmacy , University of Regensburg , Universitätsstrasse 31 , D-93053 Regensburg , Germany .
| | - Christoph Müller
- Institute of Pharmacy , Faculty of Chemistry and Pharmacy , University of Regensburg , Universitätsstrasse 31 , D-93053 Regensburg , Germany .
| | - Lukas Grätz
- Institute of Pharmacy , Faculty of Chemistry and Pharmacy , University of Regensburg , Universitätsstrasse 31 , D-93053 Regensburg , Germany .
| | - Xueke She
- Institute of Pharmacy , Faculty of Chemistry and Pharmacy , University of Regensburg , Universitätsstrasse 31 , D-93053 Regensburg , Germany .
| | - Max Keller
- Institute of Pharmacy , Faculty of Chemistry and Pharmacy , University of Regensburg , Universitätsstrasse 31 , D-93053 Regensburg , Germany .
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4
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She X, Pegoli A, Gruber CG, Wifling D, Carpenter J, Hübner H, Chen M, Wan J, Bernhardt G, Gmeiner P, Holliday ND, Keller M. Red-Emitting Dibenzodiazepinone Derivatives as Fluorescent Dualsteric Probes for the Muscarinic Acetylcholine M2 Receptor. J Med Chem 2020; 63:4133-4154. [PMID: 32233403 DOI: 10.1021/acs.jmedchem.9b02172] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Xueke She
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Andrea Pegoli
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Corinna G. Gruber
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - David Wifling
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Jessica Carpenter
- School of Life Sciences, University of Nottingham, Queen’s Medical Centre, Derby Road, Nottingham NG7 2UH, U.K
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich Alexander University, Nikolaus-Fiebiger-Straße 10, D-91058 Erlangen, Germany
| | - Mengya Chen
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Jianfei Wan
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Günther Bernhardt
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich Alexander University, Nikolaus-Fiebiger-Straße 10, D-91058 Erlangen, Germany
| | - Nicholas D. Holliday
- School of Life Sciences, University of Nottingham, Queen’s Medical Centre, Derby Road, Nottingham NG7 2UH, U.K
| | - Max Keller
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
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5
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Zhao N, Williams TM, Zhou Z, Fronczek FR, Sibrian-Vazquez M, Jois SD, Vicente MGH. Synthesis of BODIPY-Peptide Conjugates for Fluorescence Labeling of EGFR Overexpressing Cells. Bioconjug Chem 2017; 28:1566-1579. [PMID: 28414435 DOI: 10.1021/acs.bioconjchem.7b00211] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Regioselective functionalization of 2,3,5,6,8-pentachloro-BODIPY 1 produced unsymmetric BODIPY 5, bearing an isothiocyanate group suitable for conjugation, in only four steps. The X-ray structure of 5 reveals a nearly planar BODIPY core with aryl dihedral angles in the range 47.4-62.9°. Conjugation of 5 to two EGFR-targeting pegylated peptides, 3PEG-LARLLT (6) and 3PEG-GYHWYGYTPQNVI (7), under mild conditions (30 min at room temperature), afforded BODIPY conjugates 8 and 9 in 50-80% isolated yields. These conjugates showed red-shifted absorption and emission spectra compared with 5, in the near-IR region, and were evaluated as potential fluorescence imaging agents for EGFR overexpressing cells. SPR and docking investigations suggested that conjugate 8 bearing the LARLLT sequence binds to EGFR more effectively than 9 bearing the GYHWYGYTPQNVI peptide, in part due to the lower solubility of 9, and its tendency for aggregation at concentrations above 10 μM. Studies in human carcinoma HEp2 cells overexpressing EGFR demonstrated low dark and photo cytotoxicities for BODIPY 5 and the two peptide conjugates, and remarkably high cellular uptake for both conjugates 8 and 9, up to 90-fold compared with BODIPY 5 after 1 h. Fluorescence imaging studies in HEp2 cells revealed subcellular localization of the BODIPY-peptide conjugates mainly in the Golgi apparatus and the cell lysosomes. The low cytotoxicity of the new conjugates and their remarkably high uptake into EGFR overexpressing cells renders them promising imaging agents for cancers overexpressing EGFR.
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Affiliation(s)
- Ning Zhao
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Tyrslai M Williams
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Zehua Zhou
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Frank R Fronczek
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
| | - Martha Sibrian-Vazquez
- Department of Chemistry, Portland State University , Portland, Oregon 97201, United States
| | - Seetharama D Jois
- Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe , Monroe, Louisiana 71201, United States
| | - M Graça H Vicente
- Department of Chemistry, Louisiana State University , Baton Rouge, Louisiana 70803, United States
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6
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McCall JR, Goodman AJ, Jacocks HM, Thompson A, Baden DG, Bourdelais AJ. Development of a fluorescence assay for the characterization of brevenal binding to rat brain synaptosomes. JOURNAL OF NATURAL PRODUCTS 2014; 77:2014-20. [PMID: 25226846 PMCID: PMC4176390 DOI: 10.1021/np500118p] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Indexed: 06/03/2023]
Abstract
The marine dinoflagellate Karenia brevis produces a family of neurotoxins known as brevetoxins. Brevetoxins elicit their effects by binding to and activating voltage-sensitive sodium channels (VSSCs) in cell membranes. K. brevis also produces brevenal, a brevetoxin antagonist, which is able to inhibit and/or negate many of the detrimental effects of brevetoxins. Brevenal binding to VSSCs has yet to be fully characterized, in part due to the difficulty and expense of current techniques. In this study, we have developed a novel fluorescence binding assay for the brevenal binding site. Several fluorescent compounds were conjugated to brevenal to assess their effects on brevenal binding. The assay was validated against the radioligand assay for the brevenal binding site and yielded comparable equilibrium inhibition constants. The fluorescence-based assay was shown to be quicker and far less expensive and did not generate radioactive waste or need facilities for handling radioactive materials. In-depth studies using the brevenal conjugates showed that, while brevenal conjugates do bind to a binding site in the VSSC protein complex, they are not displaced by known VSSC site specific ligands. As such, brevenal elicits its action through a novel mechanism and/or currently unknown receptor site on VSSCs.
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Affiliation(s)
- Jennifer R. McCall
- Center
for Marine Science, University of North
Carolina at Wilmington, Wilmington, North Carolina 28409, United States
| | - Allan J. Goodman
- Center
for Marine Science, University of North
Carolina at Wilmington, Wilmington, North Carolina 28409, United States
| | - Henry M. Jacocks
- Center
for Marine Science, University of North
Carolina at Wilmington, Wilmington, North Carolina 28409, United States
| | - Alysha
M. Thompson
- Center
for Marine Science, University of North
Carolina at Wilmington, Wilmington, North Carolina 28409, United States
| | - Daniel G. Baden
- Center
for Marine Science, University of North
Carolina at Wilmington, Wilmington, North Carolina 28409, United States
| | - Andrea J. Bourdelais
- Center
for Marine Science, University of North
Carolina at Wilmington, Wilmington, North Carolina 28409, United States
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7
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Mountford SJ, Liu M, Zhang L, Groenen M, Herzog H, Holliday ND, Thompson PE. Synthetic routes to the Neuropeptide Y Y1 receptor antagonist 1229U91 and related analogues for SAR studies and cell-based imaging. Org Biomol Chem 2014; 12:3271-81. [PMID: 24733083 DOI: 10.1039/c4ob00176a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The potent Y1 receptor antagonist, 1229U91 has an unusual cyclic dimer structure that makes syntheses of analogue series quite challenging. We have examined three new routes to the synthesis of such peptides that has given access to novel structural variants including heterodimeric compounds, ring size variants and labelled conjugates. These compounds, including a fluorescently labelled analogue VIII show potent antagonism that can be utilised in studying Y1 receptor pharmacology.
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Affiliation(s)
- Simon J Mountford
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, VIC 3052, Australia.
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8
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Sridharan R, Zuber J, Connelly SM, Mathew E, Dumont ME. Fluorescent approaches for understanding interactions of ligands with G protein coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:15-33. [PMID: 24055822 PMCID: PMC3926105 DOI: 10.1016/j.bbamem.2013.09.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 11/18/2022]
Abstract
G protein coupled receptors are responsible for a wide variety of signaling responses in diverse cell types. Despite major advances in the determination of structures of this class of receptors, the underlying mechanisms by which binding of different types of ligands specifically elicits particular signaling responses remain unclear. The use of fluorescence spectroscopy can provide important information about the process of ligand binding and ligand dependent conformational changes in receptors, especially kinetic aspects of these processes that can be difficult to extract from X-ray structures. We present an overview of the extensive array of fluorescent ligands that have been used in studies of G protein coupled receptors and describe spectroscopic approaches for assaying binding and probing the environment of receptor-bound ligands with particular attention to examples involving yeast pheromone receptors. In addition, we discuss the use of fluorescence spectroscopy for detecting and characterizing conformational changes in receptors induced by the binding of ligands. Such studies have provided strong evidence for diversity of receptor conformations elicited by different ligands, consistent with the idea that GPCRs are not simple on and off switches. This diversity of states constitutes an underlying mechanistic basis for biased agonism, the observation that different stimuli can produce different responses from a single receptor. It is likely that continued technical advances will allow fluorescence spectroscopy to play an important role in continued probing of structural transitions in G protein coupled receptors. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.
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Affiliation(s)
- Rajashri Sridharan
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Jeffrey Zuber
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Sara M. Connelly
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Elizabeth Mathew
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Mark E. Dumont
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
- Department of Pediatrics, P.O. Box 777, University of Rochester Medical Center, Rochester, NY 14642
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9
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Tomasch M, Schwed JS, Paulke A, Stark H. Bodilisant-a novel fluorescent, highly affine histamine h3 receptor ligand. ACS Med Chem Lett 2013; 4:269-73. [PMID: 24900647 DOI: 10.1021/ml300383n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/12/2012] [Indexed: 01/17/2023] Open
Abstract
A piperidine-based lead structure for the human histamine H3 receptor (hH3R) was coupled with the BODIPY fluorophore and resulted in a strong green fluorescent (quantum yield, 0.92) hH3R ligand with affinity in the nanomolar concentration range (K i hH3R = 6.51 ± 3.31 nM), named Bodilisant. Screening for affinities at histamine and dopamine receptor subtypes showed high hH3R preference. Bodilisant was used for visualization of hH3R in hH3R overexpressing HEK-293 cells with fluorescence confocal laser scanning microscopy. In addition, in native human brain tissues, Bodilisant showed clear and displaceable images of labeled hH3R.
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Affiliation(s)
- Miriam Tomasch
- Goethe University, Max-von-Laue-Strasse 9, 60438 Frankfurt am Main, Germany
| | - J. Stephan Schwed
- Goethe University, Max-von-Laue-Strasse 9, 60438 Frankfurt am Main, Germany
| | - Alexander Paulke
- Goethe University, Kennedyallee 104, 60596 Frankfurt am Main, Germany
| | - Holger Stark
- Goethe University, Max-von-Laue-Strasse 9, 60438 Frankfurt am Main, Germany
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10
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Roa J. Role of GnRH Neurons and Their Neuronal Afferents as Key Integrators between Food Intake Regulatory Signals and the Control of Reproduction. Int J Endocrinol 2013; 2013:518046. [PMID: 24101924 PMCID: PMC3786537 DOI: 10.1155/2013/518046] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/07/2013] [Indexed: 11/17/2022] Open
Abstract
Reproductive function is regulated by a plethora of signals that integrate physiological and environmental information. Among others, metabolic factors are key components of this circuit since they inform about the propitious timing for reproduction depending on energy availability. This information is processed mainly at the hypothalamus that, in turn, modulates gonadotropin release from the pituitary and, thereby, gonadal activity. Metabolic hormones, such as leptin, insulin, and ghrelin, act as indicators of the energy status and convey this information to the reproductive axis regulating its activity. In this review, we will analyse the central mechanisms involved in the integration of this metabolic information and their contribution to the control of the reproductive function. Particular attention will be paid to summarize the participation of GnRH, Kiss1, NPY, and POMC neurons in this process and their possible interactions to contribute to the metabolic control of reproduction.
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Affiliation(s)
- Juan Roa
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Avenida Menéndez Pidal s/n, 14004 Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Spain
- Instituto Maimónides de Investigaciones Biomédicas (IMIBIC)/Hospital Universitario Reina Sofia, Córdoba, Spain
- *Juan Roa:
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11
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Roa J, Herbison AE. Direct regulation of GnRH neuron excitability by arcuate nucleus POMC and NPY neuron neuropeptides in female mice. Endocrinology 2012; 153:5587-99. [PMID: 22948210 DOI: 10.1210/en.2012-1470] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons act to sense and coordinate the brain's responses to metabolic cues. One neuronal network that is very sensitive to metabolic status is that controlling fertility. In this study, we investigated the impact of neuropeptides released by NPY and POMC neurons on the cellular excitability of GnRH neurons, the final output cells of the brain controlling fertility. The majority (∼70%) of GnRH neurons were activated by α-melanocyte-stimulating hormone, and this resulted from the direct postsynaptic activation of melanocortin receptor 3 and melanocortin receptor 4. A small population of GnRH neurons (∼15%) was excited by cocaine and amphetamine-regulated transcript or inhibited by β-endorphin. Agouti-related peptide, released by NPY neurons, was found to have variable inhibitory (∼10%) and stimulatory (∼25%) effects upon subpopulations of GnRH neurons. A variety of NPY and pancreatic polypeptide analogs was used to examine potential NPY interactions with GnRH neurons. Although porcine NPY (Y1/Y2/Y5 agonist) directly inhibited the firing of approximately 45% of GnRH neurons, [Leu(31),Pro(34)]-NPY (Y1/Y4/Y5 agonist) could excite (56%) or inhibit (19%). Experiments with further agonists indicated that Y1 receptors were responsible for suppressing GnRH neuron activity, whereas postsynaptic Y4 receptors were stimulatory. These results show that the activity of GnRH neurons is regulated in a complex manner by neuropeptides released by POMC and NPY neurons. This provides a direct route through which different metabolic cues can regulate fertility.
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Affiliation(s)
- Juan Roa
- Centre for Neuroendocrinology, Department of Physiology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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12
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McCall JR, Jacocks HM, Baden DG, Bourdelais AJ. Development of a competitive fluorescence-based synaptosome binding assay for brevetoxins. HARMFUL ALGAE 2012; 19:85-91. [PMID: 22984362 PMCID: PMC3440185 DOI: 10.1016/j.hal.2012.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Brevetoxins are a family of ladder-frame polyether toxins produced during blooms of the marine dinoflagellate Karenia brevis. Inhalation of brevetoxins aerosolized by wind and wave action can lead to asthma-like symptoms in beach goers. Consumption of either shellfish or finfish exposed to K. brevis blooms can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are due to activation of voltage-sensitive sodium channels (VSSCs) in cell membranes. Binding of brevetoxin analogs and competitors to site 5 on these channels has historically been measured using a radioligand competition assay that is fraught with difficulty, including slow analysis time, production of radioactive waste, and cumbersome and expensive methods associated with the generation of radioactive labeled ligands. In this study, we describe the development of a novel fluorescent synaptosome binding assay for the brevetoxin receptor. BODIPY(®)-conjugated to PbTx-2 was used as the labeled ligand. The BODIPY(®)-PbTx-2 conjugate was found to displace [(3)H]-PbTx-3 from its binding site on VSSCs on rat brain synaptosomes with an equilibrium inhibition constant of 0.11 nM. We have shown that brevetoxin A and B analogs are all able to compete for binding with the fluorescent ligand. Most importantly, this assay was validated against the current site 5 receptor binding assay standard, the radioligand receptor assay for the brevetoxin receptor using [(3)H]-PbTx-3 as the labeled ligand. The fluorescence based assay yielded equilibrium inhibition constants comparable to the radioligand assay for all brevetoxin analogs. The fluorescence based assay was quicker, far less expensive, and did not generate radioactive waste or need radioactive facilities. As such, this fluorescence-based assay can be used to replace the current radioligand assay for site 5 on voltage-sensitive sodium channels and will be a vital tool for future experiments examining the binding affinity of various ligands for site 5 on sodium channels.
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Affiliation(s)
- Jennifer R. McCall
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
- Corresponding Author, Tel: 910-962-2081, FAX: 910-962-2410,
| | - Henry M. Jacocks
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
| | - Daniel G. Baden
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
| | - Andrea J. Bourdelais
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
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13
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Red-fluorescent argininamide-type NPY Y1 receptor antagonists as pharmacological tools. Bioorg Med Chem 2011; 19:2859-78. [DOI: 10.1016/j.bmc.2011.03.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 03/09/2011] [Accepted: 03/18/2011] [Indexed: 11/21/2022]
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Lee JS, Kim HK, Feng S, Vendrell M, Chang YT. Accelerating fluorescent sensor discovery: unbiased screening of a diversity-oriented BODIPY library. Chem Commun (Camb) 2011; 47:2339-41. [DOI: 10.1039/c0cc04495d] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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[Lys(DOTA)4]BVD15, a novel and potent neuropeptide Y analog designed for Y1 receptor-targeted breast tumor imaging. Bioorg Med Chem Lett 2010; 20:950-3. [DOI: 10.1016/j.bmcl.2009.12.068] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 12/15/2009] [Accepted: 12/15/2009] [Indexed: 11/18/2022]
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16
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Böhme I, Beck-Sickinger AG. Illuminating the life of GPCRs. Cell Commun Signal 2009; 7:16. [PMID: 19602276 PMCID: PMC2726148 DOI: 10.1186/1478-811x-7-16] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 07/14/2009] [Indexed: 01/19/2023] Open
Abstract
The investigation of biological systems highly depends on the possibilities that allow scientists to visualize and quantify biomolecules and their related activities in real-time and non-invasively. G-protein coupled receptors represent a family of very dynamic and highly regulated transmembrane proteins that are involved in various important physiological processes. Since their localization is not confined to the cell surface they have been a very attractive "moving target" and the understanding of their intracellular pathways as well as the identified protein-protein-interactions has had implications for therapeutic interventions. Recent and ongoing advances in both the establishment of a variety of labeling methods and the improvement of measuring and analyzing instrumentation, have made fluorescence techniques to an indispensable tool for GPCR imaging. The illumination of their complex life cycle, which includes receptor biosynthesis, membrane targeting, ligand binding, signaling, internalization, recycling and degradation, will provide new insights into the relationship between spatial receptor distribution and function. This review covers the existing technologies to track GPCRs in living cells. Fluorescent ligands, antibodies, auto-fluorescent proteins as well as the evolving technologies for chemical labeling with peptide- and protein-tags are described and their major applications concerning the GPCR life cycle are presented.
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Affiliation(s)
- Ilka Böhme
- Institute of Biochemistry, Faculty of Biosciences, Pharmacy and Psychology, Leipzig University, Brüderstr, 34, 04103 Leipzig, Germany.
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Developments in fluorescent probes for receptor research. Drug Discov Today 2009; 14:706-12. [PMID: 19573791 DOI: 10.1016/j.drudis.2009.03.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 03/27/2009] [Accepted: 03/30/2009] [Indexed: 11/21/2022]
Abstract
Early reports on the identification of fluorescent probes for receptors date back to mid-1970s. Fluorescent probes were initially used to visualize molecular targets in an analogous way to the use of fluorescent antibodies but with the same resolution as isotopically labelled ligands. In parallel to the rapid development of techniques, such as fluorescence correlation spectroscopy, multi-photon excitation fluorescence microscopy, fluorescence polarization and in vivo fluorescence imaging, fluorescent probes are becoming multifaceted tools in life science. The present review will focus on how the design of fluorescent ligands for receptors has evolved to meet the needs of most recent fluorescence applications.
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Böhme I, Stichel J, Walther C, Mörl K, Beck-Sickinger AG. Agonist induced receptor internalization of neuropeptide Y receptor subtypes depends on third intracellular loop and C-terminus. Cell Signal 2008; 20:1740-9. [DOI: 10.1016/j.cellsig.2008.05.017] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 05/26/2008] [Indexed: 10/22/2022]
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Schneider E, Keller M, Brennauer A, Hoefelschweiger BK, Gross D, Wolfbeis OS, Bernhardt G, Buschauer A. Synthesis and characterization of the first fluorescent nonpeptide NPY Y1 receptor antagonist. Chembiochem 2008; 8:1981-8. [PMID: 17876753 DOI: 10.1002/cbic.200700302] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cyanine-5-labelled neuropeptide Y (NPY) was demonstrated to be an ideal universal fluorescent ligand for the combined investigation of NPY Y(1), Y(2) and Y(5) receptors. With respect to improved stability, detection of receptor subtypes in cells and tissues, and prevention of receptor internalization, small nonpeptidic fluorescent antagonists should be superior. Here we present a set of four fluorescent nonpeptide NPY Y(1) receptor (Y(1)R) antagonists. The highest affinity was obtained by labelling an N(G)-(6-aminohexanoyl)argininamide derived from the Y(1)R antagonist BIBP 3226, with Py-1, a small pyrylium dye. The fluorescent pyridinium-type Y(1)R antagonist, compound 4 had K(i) values of 29 nM and 2.7 nM, which were determined by radioligand binding and flow cytometry under equilibrium conditions, respectively; 4 had a K(b) value of 0.6 nM (Ca(2+) assay). The large Stoke's shift (541 vs. 615 nm) in buffer (PBS, pH 7.4) in the presence of 1% BSA and the red emission (quantum yield 56%) are advantageous with respect to the signal-to-noise ratio. The new probe was successfully used in fluorescence-based binding experiments evaluated by flow cytometry and confocal microscopy; this demonstrates the potential of pyrylium dyes for the preparation of fluorescent ligands that are applicable for the study of G protein-coupled receptors on living cells.
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Affiliation(s)
- Erich Schneider
- Institut für Pharmazie, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
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Ziemek R, Brennauer A, Schneider E, Cabrele C, Beck-Sickinger AG, Bernhardt G, Buschauer A. Fluorescence- and luminescence-based methods for the determination of affinity and activity of neuropeptide Y2 receptor ligands. Eur J Pharmacol 2006; 551:10-8. [PMID: 17027743 DOI: 10.1016/j.ejphar.2006.08.075] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 07/24/2006] [Accepted: 08/21/2006] [Indexed: 01/01/2023]
Abstract
With respect to the discovery and characterization of neuropeptide Y(2) receptor ligands as pharmacological tools or potential drugs, fluorescence- and luminescence-based assays were developed to determine both the affinity and the activity of receptor agonists and antagonists. A flow cytometric binding assay is described for the hY(2) receptor stably expressed in CHO cells using cy5-labeled porcine neuropeptide Y and compared with a radioligand binding assay. Binding of the fluorescent ligand was visualized by confocal microscopy. Stable co-transfection with the chimeric G protein Gq(i5) enabled the establishment of a spectrofluorimetric fura-2 and a flow cytometric fluo-4 calcium assay. Further stable expression of apoaequorin targeted to the mitochondria allowed the establishment of an aequorin assay which could be performed in the 96-well format. The shape of the concentration-response curves of porcine neuropeptide Y in the presence of the Y(2)-selective receptor antagonist BIIE0246, characteristic of either competitive or insurmountable antagonism, depended on the period of incubation with the cells. Functional data of Y(2) receptor agonists and antagonists determined in the fluorescence- and luminescence-based assays were in good agreement.
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Affiliation(s)
- Ralf Ziemek
- University of Regensburg, Institute of Pharmacy, Universitätsstr. 31, D-93040 Regensburg, Germany
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