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Pineux F, Federico S, Klotz KN, Kachler S, Michiels C, Sturlese M, Prato M, Spalluto G, Moro S, Bonifazi D. Targeting G Protein-Coupled Receptors with Magnetic Carbon Nanotubes: The Case of the A 3 Adenosine Receptor. ChemMedChem 2020; 15:1909-1920. [PMID: 32706529 DOI: 10.1002/cmdc.202000466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Indexed: 12/14/2022]
Abstract
The A3 adenosine receptor (AR) is a G protein-coupled receptor (GPCR) overexpressed in the membrane of specific cancer cells. Thus, the development of nanosystems targeting this receptor could be a strategy to both treat and diagnose cancer. Iron-filled carbon nanotubes (CNTs) are an optimal platform for theranostic purposes, and the use of a magnetic field can be exploited for cancer magnetic cell sorting and thermal therapy. In this work, we have conjugated an A3 AR ligand on the surface of iron-filled CNTs with the aim of targeting cells overexpressing A3 ARs. In particular, two conjugates bearing PEG linkers of different length were designed. A docking analysis of A3 AR showed that neither CNT nor linker interferes with ligand binding to the receptor; this was confirmed by in vitro preliminary radioligand competition assays on A3 AR. Encouraged by this result, magnetic cell sorting was applied to a mixture of cells overexpressing or not the A3 AR in which our compound displayed indiscriminate binding to all cells. Despite this, it is the first time that a GPCR ligand has been anchored to a magnetic nanosystem, thus it opens the door to new applications for cancer treatment.
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Affiliation(s)
- Florent Pineux
- Department of Chemistry and Namur Research College (NARC), University of Namur, Rue de Bruxelles 61, 5000, Namur, Belgium
| | - Stephanie Federico
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L.Giorgeri 1, 34127, Trieste, Italy
| | - Karl-Norbert Klotz
- Institut für Pharmakologie und Toxikologie, Universität Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany
| | - Sonja Kachler
- Institut für Pharmakologie und Toxikologie, Universität Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany
| | - Carine Michiels
- Namur Research Institute for Life Science (NARILIS), Unité de Recherche en Biologie Cellulaire (URBC), University of Namur, 5000, Namur, Belgium
| | - Mattia Sturlese
- Dipartimento di Scienze del Farmaco Molecular Modeling Section (MMS), Università degli Studi di Padova, Via F. Marzolo 5, 35131, Padova, Italy
| | - Maurizio Prato
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L.Giorgeri 1, 34127, Trieste, Italy.,Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo de Miramón 182, 20014, Donostia-San Sebastián, Spain.,Basque Foundation for Science, Ikerbasque, 48013, Bilbao, Spain
| | - Giampiero Spalluto
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L.Giorgeri 1, 34127, Trieste, Italy
| | - Stefano Moro
- Dipartimento di Scienze del Farmaco Molecular Modeling Section (MMS), Università degli Studi di Padova, Via F. Marzolo 5, 35131, Padova, Italy
| | - Davide Bonifazi
- Institut für Organische Chemie, Universität Wien, Währinger Str. 38, 1090, Wien, Austria
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Fatemi SM, Fatemi SJ, Abbasi Z. PAMAM dendrimer-based macromolecules and their potential applications: recent advances in theoretical studies. Polym Bull (Berl) 2020. [DOI: 10.1007/s00289-019-03076-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Tambe P, Kumar P, Paknikar KM, Gajbhiye V. Smart triblock dendritic unimolecular micelles as pioneering nanomaterials: Advancement pertaining to architecture and biomedical applications. J Control Release 2019; 299:64-89. [DOI: 10.1016/j.jconrel.2019.02.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/19/2019] [Accepted: 02/19/2019] [Indexed: 11/08/2022]
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Badalkhani-Khamseh F, Ebrahim-Habibi A, Hadipour NL. Atomistic computer simulations on multi-loaded PAMAM dendrimers: a comparison of amine- and hydroxyl-terminated dendrimers. J Comput Aided Mol Des 2017; 31:1097-1111. [DOI: 10.1007/s10822-017-0091-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/05/2017] [Indexed: 12/14/2022]
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Jain V, Maiti PK, Bharatam PV. Atomic level insights into realistic molecular models of dendrimer-drug complexes through MD simulations. J Chem Phys 2016; 145:124902. [DOI: 10.1063/1.4962582] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Vaibhav Jain
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, Mohali, Punjab 160 062, India
| | - Prabal K. Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560 012, India
| | - Prasad V. Bharatam
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, Mohali, Punjab 160 062, India
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Jones DE, Lund AM, Ghandehari H, Facelli JC. Molecular dynamics simulations in drug delivery research: Calcium chelation of G3.5 PAMAM dendrimers. COGENT CHEMISTRY 2016; 2:1229830. [PMID: 29177183 PMCID: PMC5699217 DOI: 10.1080/23312009.2016.1229830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/24/2016] [Indexed: 11/18/2022]
Abstract
Poly(amido amine) (PAMAM) dendrimers have been considered as possible delivery systems for anticancer drugs. One potential advantage of these carriers would be their use in oral formulations, which will require absorption in the intestinal lumen. This may require the opening of tight junctions which may be enabled by reducing the Ca2+ concentration in the intestinal lumen, which has been shown as an absorption mechanism for EDTA (ethylenediaminetetraacetic acid). Using molecular dynamics simulations, we show that the G3.5 PAMAM dendrimers are able to chelate Ca2+ at similar proportions to EDTA, providing support to the hypothesis that oral formulations of PAMAM dendrimers could use this high chelating efficiency as a potential mechanism for permeating the tight junctions of the intestines if other formulation barriers could be overcome.
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Affiliation(s)
- David E. Jones
- Department of Biomedical Informatics, University of Utah, 421 Wakara, Salt Lake City, UT 84108, USA
| | - Albert M. Lund
- Department of Biomedical Informatics, University of Utah, 421 Wakara, Salt Lake City, UT 84108, USA
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Hamidreza Ghandehari
- Departments of Bioengineering and Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA
- Utah Center for Nanomedicine, Nano Institute of Utah, University of Utah, Salt Lake City, UT 84112, USA
| | - Julio C. Facelli
- Department of Biomedical Informatics, University of Utah, 421 Wakara, Salt Lake City, UT 84108, USA
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Ahmed S, Vepuri SB, Kalhapure RS, Govender T. Interactions of dendrimers with biological drug targets: reality or mystery - a gap in drug delivery and development research. Biomater Sci 2016; 4:1032-50. [PMID: 27100841 DOI: 10.1039/c6bm00090h] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Dendrimers have emerged as novel and efficient materials that can be used as therapeutic agents/drugs or as drug delivery carriers to enhance therapeutic outcomes. Molecular dendrimer interactions are central to their applications and realising their potential. The molecular interactions of dendrimers with drugs or other materials in drug delivery systems or drug conjugates have been extensively reported in the literature. However, despite the growing application of dendrimers as biologically active materials, research focusing on the mechanistic analysis of dendrimer interactions with therapeutic biological targets is currently lacking in the literature. This comprehensive review on dendrimers over the last 15 years therefore attempts to identify the reasons behind the apparent lack of dendrimer-receptor research and proposes approaches to address this issue. The structure, hierarchy and applications of dendrimers are briefly highlighted, followed by a review of their various applications, specifically as biologically active materials, with a focus on their interactions at the target site. It concludes with a technical guide to assist researchers on how to employ various molecular modelling and computational approaches for research on dendrimer interactions with biological targets at a molecular level. This review highlights the impact of a mechanistic analysis of dendrimer interactions on a molecular level, serves to guide and optimise their discovery as medicinal agents, and hopes to stimulate multidisciplinary research between scientific, experimental and molecular modelling research teams.
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Affiliation(s)
- Shaimaa Ahmed
- Discipline of Pharmaceutical Sciences, School of Health Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
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Chen JF, Lee CF, Chern Y. Adenosine receptor neurobiology: overview. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 119:1-49. [PMID: 25175959 DOI: 10.1016/b978-0-12-801022-8.00001-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Adenosine is a naturally occurring nucleoside that is distributed ubiquitously throughout the body as a metabolic intermediary. In the brain, adenosine functions as an important upstream neuromodulator of a broad spectrum of neurotransmitters, receptors, and signaling pathways. By acting through four G-protein-coupled receptors, adenosine contributes critically to homeostasis and neuromodulatory control of a variety of normal and abnormal brain functions, ranging from synaptic plasticity, to cognition, to sleep, to motor activity to neuroinflammation, and cell death. This review begun with an overview of the gene and genome structure and the expression pattern of adenosine receptors (ARs). We feature several new developments over the past decade in our understanding of AR functions in the brain, with special focus on the identification and characterization of canonical and noncanonical signaling pathways of ARs. We provide an update on functional insights from complementary genetic-knockout and pharmacological studies on the AR control of various brain functions. We also highlight several novel and recent developments of AR neurobiology, including (i) recent breakthrough in high resolution of three-dimension structure of adenosine A2A receptors (A2ARs) in several functional status, (ii) receptor-receptor heterodimerization, (iii) AR function in glial cells, and (iv) the druggability of AR. We concluded the review with the contention that these new developments extend and strengthen the support for A1 and A2ARs in brain as therapeutic targets for neurologic and psychiatric diseases.
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Affiliation(s)
- Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Chien-fei Lee
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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Martinho N, Florindo H, Silva L, Brocchini S, Zloh M, Barata T. Molecular Modeling to Study Dendrimers for Biomedical Applications. Molecules 2014; 19:20424-20467. [PMID: 25493631 PMCID: PMC6270869 DOI: 10.3390/molecules191220424] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/12/2014] [Accepted: 11/17/2014] [Indexed: 02/06/2023] Open
Abstract
Molecular modeling techniques provide a powerful tool to study the properties of molecules and their interactions at the molecular level. The use of computational techniques to predict interaction patterns and molecular properties can inform the design of drug delivery systems and therapeutic agents. Dendrimers are hyperbranched macromolecular structures that comprise repetitive building blocks and have defined architecture and functionality. Their unique structural features can be exploited to design novel carriers for both therapeutic and diagnostic agents. Many studies have been performed to iteratively optimise the properties of dendrimers in solution as well as their interaction with drugs, nucleic acids, proteins and lipid membranes. Key features including dendrimer size and surface have been revealed that can be modified to increase their performance as drug carriers. Computational studies have supported experimental work by providing valuable insights about dendrimer structure and possible molecular interactions at the molecular level. The progress in computational simulation techniques and models provides a basis to improve our ability to better predict and understand the biological activities and interactions of dendrimers. This review will focus on the use of molecular modeling tools for the study and design of dendrimers, with particular emphasis on the efforts that have been made to improve the efficacy of this class of molecules in biomedical applications.
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Affiliation(s)
- Nuno Martinho
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, Lisbon 1649-003, Portugal
| | - Helena Florindo
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, Lisbon 1649-003, Portugal
| | - Liana Silva
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, Lisbon 1649-003, Portugal
| | - Steve Brocchini
- Department of Pharmaceutics, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, UK
| | - Mire Zloh
- Department of Pharmacy, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK.
| | - Teresa Barata
- Department of Pharmaceutics, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, UK.
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Jain V, Bharatam PV. Pharmacoinformatic approaches to understand complexation of dendrimeric nanoparticles with drugs. NANOSCALE 2014; 6:2476-2501. [PMID: 24441940 DOI: 10.1039/c3nr05400d] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Nanoparticle based drug delivery systems are gaining popularity due to their wide spectrum advantages over traditional drug delivery systems; among them, dendrimeric nano-vectors are the most widely explored carriers for pharmaceutical and biomedical applications. The precise mechanism of encapsulation of drug molecules inside the dendritic matrix, delivery of drugs into specific cells, interactions of nano-formulation with biological targets and proteins, etc. present a substantial challenge to the scientific understanding of the subject. Computational methods complement experimental techniques in the design and optimization of drug delivery systems, thus minimizing the investment in drug design and development. Significant progress in computer simulations could facilitate an understanding of the precise mechanism of encapsulation of bioactive molecules and their delivery. This review summarizes the pharmacoinformatic studies spanning from quantum chemical calculations to coarse-grained simulations, aimed at providing better insight into dendrimer-drug interactions and the physicochemical parameters influencing the binding and release mechanism of drugs.
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Affiliation(s)
- Vaibhav Jain
- Department of Medicinal Chemistry, Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, Punjab 160 062, India.
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Jacobson KA. Structure-based approaches to ligands for G-protein-coupled adenosine and P2Y receptors, from small molecules to nanoconjugates. J Med Chem 2013; 56:3749-67. [PMID: 23597047 PMCID: PMC3701956 DOI: 10.1021/jm400422s] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Adenosine receptor (ARs) and P2Y receptors (P2YRs) that respond to extracellular nucleosides/nucleotides are associated with new directions for therapeutics. The X-ray structures of the A2AAR complexes with agonists and antagonists are examined in relationship to the G-protein-coupled receptor (GPCR) superfamily and applied to drug discovery. Much of the data on AR ligand structure from early SAR studies now are explainable from the A2AAR X-ray crystallography. The ligand-receptor interactions in related GPCR complexes can be identified by means of modeling approaches, e.g., molecular docking. Thus, molecular recognition in binding and activation processes has been studied effectively using homology modeling and applied to ligand design. Virtual screening has yielded new nonnucleoside AR antagonists, and existing ligands have been improved with knowledge of the receptor interactions. New agonists are being explored for central nervous system and peripheral therapeutics based on in vivo activity, such as chronic neuropathic pain. Ligands for receptors more distantly related to the X-ray template, i.e., P2YRs, have been introduced and are mainly used as pharmacological tools for elucidating the physiological role of extracellular nucleotides. Other ligand tools for drug discovery include fluorescent probes, radioactive probes, multivalent probes, and functionalized nanoparticles.
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892, USA.
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Tian WD, Ma YQ. Theoretical and computational studies of dendrimers as delivery vectors. Chem Soc Rev 2013; 42:705-27. [PMID: 23114420 DOI: 10.1039/c2cs35306g] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
It is a great challenge for nanomedicine to develop novel dendrimers with maximum therapeutic potential and minimum side-effects for drug and gene delivery. As delivery vectors, dendrimers must overcome lots of barriers before delivering the bio-agents to the target in the cell. Extensive experimental investigations have been carried out to elucidate the physical and chemical properties of dendrimers and explore their behaviors when interacting with biomolecules, such as gene materials, proteins, and lipid membranes. As a supplement of the experimental techniques, it has been proved that computer simulations could facilitate the progress in understanding the delivery process of bioactive molecules. The structures of dendrimers in dilute solutions have been intensively investigated by monomer-resolved simulations, coarse-grained simulations, and atom-resolved simulations. Atomistic simulations have manifested that the hydrophobic interactions, hydrogen-bond interactions, and electrostatic attraction play critical roles in the formation of dendrimer-drug complexes. Multiscale simulations and statistical field theories have uncovered some physical mechanisms involved in the dendrimer-based gene delivery systems. This review will focus on the current status and perspective of theoretical and computational contributions in this field in recent years. (275 references).
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Affiliation(s)
- Wen-de Tian
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
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Lewis T, Ganesan V. Mean-Field Modeling of the Encapsulation of Weakly Acidic Molecules in Polyelectrolyte Dendrimers. J Phys Chem B 2012; 116:8269-81. [DOI: 10.1021/jp3033066] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Thomas Lewis
- Department of Chemical Engineering, University of Texas at Austin, Austin,
Texas 78712, United States
| | - Venkat Ganesan
- Department of Chemical Engineering, University of Texas at Austin, Austin,
Texas 78712, United States
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Maingi V, Kumar MVS, Maiti PK. PAMAM Dendrimer–Drug Interactions: Effect of pH on the Binding and Release Pattern. J Phys Chem B 2012; 116:4370-6. [DOI: 10.1021/jp211515g] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Vishal Maingi
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560 012, India
| | | | - Prabal K. Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560 012, India
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Tosh DK, Phan K, Deflorian F, Wei Q, Yoo LS, Gao ZG, Jacobson KA. Click modification in the N6 region of A3 adenosine receptor-selective carbocyclic nucleosides for dendrimeric tethering that preserves pharmacophore recognition. Bioconjug Chem 2012; 23:232-47. [PMID: 22175234 PMCID: PMC3291892 DOI: 10.1021/bc200526c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Adenosine derivatives were modified with alkynyl groups on N(6) substituents for linkage to carriers using Cu(I)-catalyzed click chemistry. Two parallel series, both containing a rigid North-methanocarba (bicyclo[3.1.0]hexane) ring system in place of ribose, behaved as A(3) adenosine receptor (AR) agonists: (5'-methyluronamides) or partial agonists (4'-truncated). Terminal alkynyl groups on a chain at the 3 position of a N(6)-benzyl group or simply through a N(6)-propargyl group were coupled to azido derivatives, which included both small molecules and G4 (fourth-generation) multivalent poly(amidoamine) (PAMAM) dendrimers, to form 1,2,3-triazolyl linkers. The small molecular triazoles probed the tolerance in A(3)AR binding of distal, sterically bulky groups such as 1-adamantyl. Terminal 4-fluoro-3-nitrophenyl groups anticipated nucleophilic substitution for chain extension and (18)F radiolabeling. N(6)-(4-Fluoro-3-nitrophenyl)-triazolylmethyl derivative 32 displayed a K(i) of 9.1 nM at A(3)AR with ∼1000-fold subtype selectivity. Multivalent conjugates additionally containing click-linked water-solubilizing polyethylene glycol groups potently activated A(3)AR in the 5'-methyluronamide, but not 4' truncated series. N(6)-Benzyl nucleoside conjugate 43 (apparent K(i) 24 nM) maintained binding affinity of the monomer better than a N(6)-triazolylmethyl derivative. Thus, the N(6) region of 5'-methyluronamide derivatives, as modeled in receptor docking, is suitable for functionalization and tethering by click chemistry to achieve high A(3)AR agonist affinity and enhanced selectivity.
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Affiliation(s)
- Dilip K. Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Khai Phan
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Francesca Deflorian
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Qiang Wei
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Lena S. Yoo
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Barata TS, Teo I, Brocchini S, Zloh M, Shaunak S. Partially glycosylated dendrimers block MD-2 and prevent TLR4-MD-2-LPS complex mediated cytokine responses. PLoS Comput Biol 2011; 7:e1002095. [PMID: 21738462 PMCID: PMC3127813 DOI: 10.1371/journal.pcbi.1002095] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 05/04/2011] [Indexed: 01/04/2023] Open
Abstract
The crystal structure of the TLR4-MD-2-LPS complex responsible for triggering powerful pro-inflammatory cytokine responses has recently become available. Central to cell surface complex formation is binding of lipopolysaccharide (LPS) to soluble MD-2. We have previously shown, in biologically based experiments, that a generation 3.5 PAMAM dendrimer with 64 peripheral carboxylic acid groups acts as an antagonist of pro-inflammatory cytokine production after surface modification with 8 glucosamine molecules. We have also shown using molecular modelling approaches that this partially glycosylated dendrimer has the flexibility, cluster density, surface electrostatic charge, and hydrophilicity to make it a therapeutically useful antagonist of complex formation. These studies enabled the computational study of the interactions of the unmodified dendrimer, glucosamine, and of the partially glycosylated dendrimer with TLR4 and MD-2 using molecular docking and molecular dynamics techniques. They demonstrate that dendrimer glucosamine forms co-operative electrostatic interactions with residues lining the entrance to MD-2's hydrophobic pocket. Crucially, dendrimer glucosamine interferes with the electrostatic binding of: (i) the 4'phosphate on the di-glucosamine of LPS to Ser118 on MD-2; (ii) LPS to Lys91 on MD-2; (iii) the subsequent binding of TLR4 to Tyr102 on MD-2. This is followed by additional co-operative interactions between several of the dendrimer glucosamine's carboxylic acid branches and MD-2. Collectively, these interactions block the entry of the lipid chains of LPS into MD-2's hydrophobic pocket, and also prevent TLR4-MD-2-LPS complex formation. Our studies have therefore defined the first nonlipid-based synthetic MD-2 antagonist using both animal model-based studies of pro-inflammatory cytokine responses and molecular modelling studies of a whole dendrimer with its target protein. Using this approach, it should now be possible to computationally design additional macromolecular dendrimer based antagonists for other Toll Like Receptors. They could be useful for treating a spectrum of infectious, inflammatory and malignant diseases.
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Affiliation(s)
- Teresa S. Barata
- Center for Structural Chemistry, School of Pharmacy, University of London, London, United Kingdom
- Departments of Medicine, Infection & Immunity, Imperial College London, London, United Kingdom
| | - Ian Teo
- Departments of Medicine, Infection & Immunity, Imperial College London, London, United Kingdom
| | - Steve Brocchini
- Center for Structural Chemistry, School of Pharmacy, University of London, London, United Kingdom
| | - Mire Zloh
- Center for Structural Chemistry, School of Pharmacy, University of London, London, United Kingdom
| | - Sunil Shaunak
- Departments of Medicine, Infection & Immunity, Imperial College London, London, United Kingdom
- * E-mail:
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Nyitrai G, Kékesi O, Pál I, Keglevich P, Csíki Z, Fügedi P, Simon Á, Fitos I, Németh K, Visy J, Tárkányi G, Kardos J. Assessing toxicity of polyamidoamine dendrimers by neuronal signaling functions. Nanotoxicology 2011; 6:576-86. [DOI: 10.3109/17435390.2011.591511] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Kecskés A, Tosh DK, Wei Q, Gao ZG, Jacobson KA. GPCR ligand dendrimer (GLiDe) conjugates: adenosine receptor interactions of a series of multivalent xanthine antagonists. Bioconjug Chem 2011; 22:1115-27. [PMID: 21539392 DOI: 10.1021/bc1005812] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Previously, G protein-coupled receptor (GPCR) agonists were tethered from polyamidoamine (PAMAM) dendrimers to provide high receptor affinity and selectivity. Here, we prepared GPCR ligand--dendrimer (GLiDe) conjugates from a potent adenosine receptor (AR) antagonist; such agents are of interest for treating Parkinson's disease, asthma, and other conditions. Xanthine amine congener (XAC) was appended with an alkyne group on an extended C8 substituent for coupling by Cu(I)-catalyzed click chemistry to azide-derivatized G4 (fourth-generation) PAMAM dendrimers to form triazoles. These conjugates also contained triazole-linked PEG groups (8 or 22 moieties per 64 terminal positions) for increasing water-solubility and optionally prosthetic groups for spectroscopic characterization and affinity labeling. Human AR binding affinity increased progressively with the degree of xanthine substitution to reach K(i) values in the nanomolar range. The order of affinity of each conjugate was hA(2A)AR > hA(3)AR > hA(1)AR, while the corresponding monomer was ranked hA(2A)AR > hA(1)AR ≥ hA(3)AR. The antagonist activity of the most potent conjugate 14 (34 xanthines per dendrimer) was examined at the G(i)-coupled A(1)AR. Conjugate 14 at 100 nM right-shifted the AR agonist concentration--response curve in a cyclic AMP functional assay in a parallel manner, but at 10 nM (lower than its K(i) value), it significantly suppressed the maximal agonist effect in calcium mobilization. This is the first systematic probing of a potent AR antagonist tethered on a dendrimer and its activity as a function of variable loading.
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Affiliation(s)
- Angela Kecskés
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
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Chen JF, Chern Y. Impacts of methylxanthines and adenosine receptors on neurodegeneration: human and experimental studies. Handb Exp Pharmacol 2011:267-310. [PMID: 20859800 DOI: 10.1007/978-3-642-13443-2_10] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Neurodegenerative disorders are some of the most feared illnesses in modern society, with no effective treatments to slow or halt this neurodegeneration. Several decades after the earliest attempt to treat Parkinson's disease using caffeine, tremendous amounts of information regarding the potential beneficial effect of caffeine as well as adenosine drugs on major neurodegenerative disorders have accumulated. In the first part of this review, we provide general background on the adenosine receptor signaling systems by which caffeine and methylxanthine modulate brain activity and their role in relationship to the development and treatment of neurodegenerative disorders. The demonstration of close interaction between adenosine receptor and other G protein coupled receptors and accessory proteins might offer distinct pharmacological properties from adenosine receptor monomers. This is followed by an outline of the major mechanism underlying neuroprotection against neurodegeneration offered by caffeine and adenosine receptor agents. In the second part, we discuss the current understanding of caffeine/methylxantheine and its major target adenosine receptors in development of individual neurodegenerative disorders, including stroke, traumatic brain injury Alzheimer's disease, Parkinson's disease, Huntington's disease and multiple sclerosis. The exciting findings to date include the specific in vivo functions of adenosine receptors revealed by genetic mouse models, the demonstration of a broad spectrum of neuroprotection by chronic treatment of caffeine and adenosine receptor ligands in animal models of neurodegenerative disorders, the encouraging development of several A(2A) receptor selective antagonists which are now in advanced clinical phase III trials for Parkinson's disease. Importantly, increasing body of the human and experimental studies reveals encouraging evidence that regular human consumption of caffeine in fact may have several beneficial effects on neurodegenerative disorders, from motor stimulation to cognitive enhancement to potential neuroprotection. Thus, with regard to neurodegenerative disorders, these potential benefits of methylxanthines, caffeine in particular, strongly argue against the common practice by clinicians to discourage regular human consumption of caffeine in aging populations.
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Affiliation(s)
- Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
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Jacobson KA. GPCR ligand-dendrimer (GLiDe) conjugates: future smart drugs? Trends Pharmacol Sci 2010; 31:575-9. [PMID: 20961625 DOI: 10.1016/j.tips.2010.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 09/15/2010] [Accepted: 09/16/2010] [Indexed: 10/18/2022]
Abstract
Unlike nanocarriers that are intended to release their drug cargo at the site of action, biocompatibile polyamidoamine (PAMAM) conjugates are designed to act at cell surface G protein-coupled receptors (GPCRs) without drug release. These multivalent GPCR ligand-dendrimer (GLiDe) conjugates display qualitatively different pharmacological properties in comparison with monomeric drugs. They might be useful as novel tools to study GPCR homodimers and heterodimers as well as higher aggregates. The structure of the conjugate determines the profile of biological activity, receptor selectivity, and physical properties such as water solubility. Prosthetic groups for characterization and imaging of receptors can be introduced without loss of affinity. The feasibility of targeting multiple adenosine and P2Y receptors for synergistic effects has been shown. Testing in vivo will be needed to explore the effects on pharmacokinetics and tissue targeting.
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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Keene AM, Balasubramanian R, Lloyd J, Shainberg A, Jacobson KA. Multivalent dendrimeric and monomeric adenosine agonists attenuate cell death in HL-1 mouse cardiomyocytes expressing the A(3) receptor. Biochem Pharmacol 2010; 80:188-96. [PMID: 20346920 PMCID: PMC2880883 DOI: 10.1016/j.bcp.2010.03.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 03/15/2010] [Accepted: 03/16/2010] [Indexed: 11/15/2022]
Abstract
Multivalent dendrimeric conjugates of GPCR ligands may have increased potency or selectivity in comparison to monomeric ligands, a phenomenon that was tested in a model of cytoprotection in mouse HL-1 cardiomyocytes. Quantitative RT-PCR indicated high expression levels of endogenous A(1) and A(2A) adenosine receptors (ARs), but not of A(2B) and A(3)ARs. Activation of the heterologously expressed human A(3)AR in HL-1 cells by AR agonists significantly attenuated cell damage following 4h exposure to H(2)O(2) (750 microM) but not in untransfected cells. The A(3) agonist IB-MECA (EC(50) 3.8 microM) and the non-selective agonist NECA (EC(50) 3.9 microM) protected A(3) AR-transfected cells against H(2)O(2) in a concentration-dependent manner, as determined by lactate dehydrogenase release. A generation 5.5 PAMAM (polyamidoamine) dendrimeric conjugate of a N(6)-chain-functionalized adenosine agonist was synthesized and its mass indicated an average of 60 amide-linked nucleoside moieties out of 256 theoretical attachment sites. It non-selectively activated the A(3)AR to inhibit forskolin-stimulated cAMP formation (IC(50) 66nM) and, similarly, protected A(3)-transfected HL-1 cells from apoptosis-inducing H(2)O(2) with greater potency (IC(50) 35nM) than monomeric nucleosides. Thus, a PAMAM conjugate retained AR binding affinity and displayed greatly enhanced cardioprotective potency.
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Affiliation(s)
- Athena M. Keene
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - Ramachandran Balasubramanian
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - John Lloyd
- Mass Spectrometry Facility, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - Asher Shainberg
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
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Tosh DK, Yoo LS, Chinn M, Hong K, Kilbey SM, Barrett MO, Fricks IP, Harden TK, Gao ZG, Jacobson KA. Polyamidoamine (PAMAM) dendrimer conjugates of "clickable" agonists of the A3 adenosine receptor and coactivation of the P2Y14 receptor by a tethered nucleotide. Bioconjug Chem 2010; 21:372-84. [PMID: 20121074 PMCID: PMC2845915 DOI: 10.1021/bc900473v] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We previously synthesized a series of potent and selective A(3) adenosine receptor (AR) agonists (North-methanocarba nucleoside 5'-uronamides) containing dialkyne groups on extended adenine C2 substituents. We coupled the distal alkyne of a 2-octadiynyl nucleoside by Cu(I)-catalyzed "click" chemistry to azide-derivatized G4 (fourth-generation) PAMAM dendrimers to form triazoles. A(3)AR activation was preserved in these multivalent conjugates, which bound with apparent K(i) of 0.1-0.3 nM. They were substituted with nucleoside moieties, solely or in combination with water-solubilizing carboxylic acid groups derived from hexynoic acid. A comparison with various amide-linked dendrimers showed that triazole-linked conjugates displayed selectivity and enhanced A(3)AR affinity. We prepared a PAMAM dendrimer containing equiproportioned peripheral azido and amino groups for conjugation of multiple ligands. A bifunctional conjugate activated both A(3) and P2Y(14) receptors (via amide-linked uridine-5'-diphosphoglucuronic acid), with selectivity in comparison to other ARs and P2Y receptors. This is the first example of targeting two different GPCRs with the same dendrimer conjugate, which is intended for activation of heteromeric GPCR aggregates. Synergistic effects of activating multiple GPCRs with a single dendrimer conjugate might be useful in disease treatment.
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Affiliation(s)
- Dilip K. Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Lena S. Yoo
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Moshe Chinn
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Kunlun Hong
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - S. Michael Kilbey
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Matthew O. Barrett
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - Ingrid P. Fricks
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - T. Kendall Harden
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Giarolla J, Rando DG, Pasqualoto KF, Zaim MH, Ferreira EI. Molecular modeling as a promising tool to study dendrimer prodrugs delivery. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.theochem.2009.09.050] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kim Y, Hechler B, Gao ZG, Gachet C, Jacobson KA. PEGylated dendritic unimolecular micelles as versatile carriers for ligands of G protein-coupled receptors. Bioconjug Chem 2009; 20:1888-98. [PMID: 19785401 DOI: 10.1021/bc9001689] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Despite its widespread application in nanomedicine, poly(ethylene glycol) (PEG) is seldom used for covalent modification of ligands for G protein-coupled receptors (GPCRs) due to potential steric complications. In order to study the influence of PEG chains on the biological activity of GPCR ligands bound to a common macromolecular carrier, we prepared a series of G3 polyamidoamine (PAMAM) dendrimers derivatized with Alexa Fluor 488, varying numbers of PEG(550)/PEG(750)/PEG(2000), and nucleoside moieties derived from the A(2A) adenosine receptor (AR) agonist CGS21680 (2-[4-(2-carboxylethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenosine). These dendrimer conjugates were purified by size exclusion chromatography and characterized by (1)H NMR and MALDI MS. In radioligand binding assays, some PAMAM-PEG conjugates showed enhanced subtype-selectivity at the human A(2A) AR compared to monomeric ligands of comparable affinity. The functional potency was measured in the A(2A) AR-mediated activation of adenylate cyclase and inhibition of ADP-induced platelet aggregation. Interestingly, the dendrimer conjugate 10c bearing 11 PEG(750) chains (out of theoretical 32 amino end groups) and 14 nucleoside moieties was 5-fold more potent in A(2A) AR-mediated stimulation of cyclic AMP formation than 10d with 4 PEG(2000) chains and 21 nucleosides, although the binding affinities of these 2 compounds were similar. Thus, a relatively small (≤10 nm) multivalent ligand 10c modified for water solubility maintained high potency and displayed increased A(2A) AR binding selectivity over the monomeric nucleosides. The current study demonstrates the feasibility of using short PEG chains in the design of carriers that target ligand-receptor interactions.
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Affiliation(s)
- Yoonkyung Kim
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Das A, Zhou Y, Ivanov AA, Carter RL, Harden TK, Jacobson KA. Enhanced potency of nucleotide-dendrimer conjugates as agonists of the P2Y14 receptor: multivalent effect in G protein-coupled receptor recognition. Bioconjug Chem 2009; 20:1650-9. [PMID: 19572637 DOI: 10.1021/bc900206g] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The P2Y(14) receptor is a G protein-coupled receptor activated by uridine-5'-diphosphoglucose and other nucleotide sugars that modulates immune function. Covalent conjugation of P2Y(14) receptor agonists to PAMAM (polyamidoamine) dendrimers enhanced pharmacological activity. Uridine-5'-diphosphoglucuronic acid (UDPGA) and its ethylenediamine adduct were suitable functionalized congeners for coupling to several generations (G2.5-6) of dendrimers (both terminal carboxy and amino). Prosthetic groups, including biotin for avidin complexation, a chelating group for metal complexation (and eventual magnetic resonance imaging), and a fluorescent moiety, also were attached with the eventual goals of molecular detection and characterization of the P2Y(14) receptor. The activities of conjugates were assayed in HEK293 cells stably expressing the human P2Y(14) receptor. A G3 PAMAM conjugate containing 20 bound nucleotide moieties (UDPGA) was 100-fold more potent (EC(50) 2.4 nM) than the native agonist uridine-5'-diphosphoglucose. A molecular model of this conjugate docked in the human P2Y(14) receptor showed that the nucleotide-substituted branches could extend far beyond the dimensions of the receptor and be available for multivalent docking to receptor aggregates. Larger dendrimer carriers and greater loading favored higher potency. A similar conjugate of G6 with 147 out of 256 amino groups substituted with UDPGA displayed an EC(50) value of 0.8 nM. Thus, biological activity was either retained or dramatically enhanced in the multivalent dendrimer conjugates in comparison with monomeric P2Y(14) receptor agonists, depending on size, degree of substitution, terminal functionality, and attached prosthetic groups.
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Affiliation(s)
- Arijit Das
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Jacobson KA. Functionalized congener approach to the design of ligands for G protein-coupled receptors (GPCRs). Bioconjug Chem 2009; 20:1816-35. [PMID: 19405524 DOI: 10.1021/bc9000596] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Functionalized congeners, in which a chemically functionalized chain is incorporated at an insensitive site on a pharmacophore, have been designed from the agonist and antagonist ligands of various G protein-coupled receptors (GPCRs). These chain extensions enable a conjugation strategy for detecting and characterizing GPCR structure and function and pharmacological modulation. The focus in many studies of functionalized congeners has been on two families of GPCRs: those responding to extracellular purines and pyrimidines-i.e., adenosine receptors (ARs) and P2Y nucleotide receptors. Functionalized congeners of small molecule as ligands for other GPCRs and non-G protein coupled receptors have also been designed. For example, among biogenic amine neurotransmitter receptors, muscarinic acetylcholine receptor antagonists and adrenergic receptor ligands have been studied with a functionalized congener approach. Adenosine A(1), A(2A), and A(3) receptor functionalized congeners have yielded macromolecular conjugates, irreversibly binding AR ligands for receptor inactivation and cross-linking, radioactive probes that use prosthetic groups, immobilized ligands for affinity chromatography, and dual-acting ligands that function as binary drugs. Poly(amidoamine) dendrimers have served as nanocarriers for covalently conjugated AR functionalized congeners. Rational methods of ligand design derived from molecular modeling and templates have been included in these studies. Thus, the design of novel ligands, both small molecules and macromolecular conjugates, for studying the chemical and biological properties of GPCRs have been developed with this approach, has provided researchers with a strategy that is more versatile than the classical medicinal chemical approaches.
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Adenosine acts as a cytoprotective modulator in response to stress to an organ or tissue. Although short-lived in the circulation, it can activate four subtypes of G protein-coupled adenosine receptors (ARs): A(1), A(2A), A(2B), and A(3). The alkylxanthines caffeine and theophylline are the prototypical antagonists of ARs, and their stimulant actions occur primarily through this mechanism. For each of the four AR subtypes, selective agonists and antagonists have been introduced and used to develop new therapeutic drug concepts. ARs are notable among the GPCR family in the number and variety of agonist therapeutic candidates that have been proposed. The selective and potent synthetic AR agonists, which are typically much longer lasting in the body than adenosine, have potential therapeutic applications based on their anti-inflammatory (A(2A) and A(3)), cardioprotective (preconditioning by A(1) and A(3) and postconditioning by A(2B)), cerebroprotective (A(1) and A(3)), and antinociceptive (A(1)) properties. Potent and selective AR antagonists display therapeutic potential as kidney protective (A(1)), antifibrotic (A(2A)), neuroprotective (A(2A)), and antiglaucoma (A(3)) agents. AR agonists for cardiac imaging and positron-emitting AR antagonists are in development for diagnostic applications. Allosteric modulators of A(1) and A(3) ARs have been described. In addition to the use of selective agonists/antagonists as pharmacological tools, mouse strains in which an AR has been genetically deleted have aided in developing novel drug concepts based on the modulation of ARs.
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Biooorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810, USA.
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Klutz AM, Gao ZG, Lloyd J, Shainberg A, Jacobson KA. Enhanced A3 adenosine receptor selectivity of multivalent nucleoside-dendrimer conjugates. J Nanobiotechnology 2008; 6:12. [PMID: 18947419 PMCID: PMC2582240 DOI: 10.1186/1477-3155-6-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Accepted: 10/23/2008] [Indexed: 11/18/2022] Open
Abstract
Background An approach to use multivalent dendrimer carriers for delivery of nucleoside signaling molecules to their cell surface G protein-coupled receptors (GPCRs) was recently introduced. Results A known adenosine receptor (AR) agonist was conjugated to polyamidoamine (PAMAM) dendrimer carriers for delivery of the intact covalent conjugate to on the cell surface. Depending on the linking moiety, multivalent conjugates of the N6-chain elongated functionalized congener ADAC (N6-[4-[[[4-[[[(2-aminoethyl)amino]carbonyl]methyl]anilino]carbonyl]methyl]phenyl]-adenosine) achieved unanticipated high selectivity in binding to the cytoprotective human A3 AR, a class A GPCR. The key to this selectivity of > 100-fold in both radioreceptor binding (Ki app = 2.4 nM) and functional assays (EC50 = 1.6 nM in inhibition of adenylate cyclase) was maintaining a free amino group (secondary) in an amide-linked chain. Attachment of neutral amide-linked chains or thiourea-containing chains preserved the moderate affinity and efficacy at the A1 AR subtype, but there was no selectivity for the A3 AR. Since residual amino groups on dendrimers are associated with cytotoxicity, the unreacted terminal positions of this A3 AR-selective G2.5 dendrimer were present as carboxylate groups, which had the further benefit of increasing water-solubility. The A3 AR selective G2.5 dendrimer was also visualized binding the membrane of cells expressing the A3 receptor but did not bind cells that did not express the receptor. Conclusion This is the first example showing that it is feasible to modulate and even enhance the pharmacological profile of a ligand of a GPCR based on conjugation to a nanocarrier and the precise structure of the linking group, which was designed to interact with distal extracellular regions of the 7 transmembrane-spanning receptor. This ligand tool can now be used in pharmacological models of tissue rescue from ischemia and to probe the existence of A3 AR dimers.
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Affiliation(s)
- Athena M Klutz
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.
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