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Janicot R, Garcia-Marcos M. Get Ready to Sharpen Your Tools: A Short Guide to Heterotrimeric G Protein Activity Biosensors. Mol Pharmacol 2024; 106:129-144. [PMID: 38991745 PMCID: PMC11331509 DOI: 10.1124/molpharm.124.000949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/27/2024] [Accepted: 07/01/2024] [Indexed: 07/13/2024] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest class of transmembrane receptors encoded in the human genome, and they initiate cellular responses triggered by a plethora of extracellular stimuli ranging from neurotransmitters and hormones to photons. Upon stimulation, GPCRs activate heterotrimeric G proteins (Gαβγ) in the cytoplasm, which then convey signals to their effectors to elicit cellular responses. Given the broad biological and biomedical relevance of GPCRs and G proteins in physiology and disease, there is great interest in developing and optimizing approaches to measure their signaling activity with high accuracy and across experimental systems pertinent to their functions in cellular communication. This review provides a historical perspective on approaches to measure GPCR-G protein signaling, from quantification of second messengers and other indirect readouts of activity to biosensors that directly detect the activity of G proteins. The latter is the focus of a more detailed overview of the evolution of design principles for various optical biosensors of G protein activity with different experimental capabilities. We will highlight advantages and limitations of biosensors that detect different G protein activation hallmarks, like dissociation of Gα and Gβγ or nucleotide exchange on Gα, as well as their suitability to detect signaling mediated by endogenous versus exogenous signaling components or in physiologically relevant systems like primary cells. Overall, this review intends to provide an assessment of the state-of-the-art for biosensors that directly measure G protein activity to allow readers to make informed decisions on the selection and implementation of currently available tools. SIGNIFICANCE STATEMENT: G protein activity biosensors have become essential and widespread tools to assess GPCR signaling and pharmacology. Yet, investigators face the challenge of choosing from a growing list of G protein activity biosensors. This review provides an overview of the features and capabilities of different optical biosensor designs for the direct detection of G protein activity in cells, with the aim of facilitating the rational selection of systems that align with the specific scientific questions and needs of investigators.
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Affiliation(s)
- Remi Janicot
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine (R.J., M.G.-M.) and Department of Biology, College of Arts & Sciences (M.G.-M.), Boston University, Boston, Massachusetts
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine (R.J., M.G.-M.) and Department of Biology, College of Arts & Sciences (M.G.-M.), Boston University, Boston, Massachusetts
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2
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Transcriptional adaptation of olfactory sensory neurons to GPCR identity and activity. Nat Commun 2022; 13:2929. [PMID: 35614043 PMCID: PMC9132991 DOI: 10.1038/s41467-022-30511-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 05/04/2022] [Indexed: 01/02/2023] Open
Abstract
In mammals, chemoperception relies on a diverse set of neuronal sensors able to detect chemicals present in the environment, and to adapt to various levels of stimulation. The contribution of endogenous and external factors to these neuronal identities remains to be determined. Taking advantage of the parallel coding lines present in the olfactory system, we explored the potential variations of neuronal identities before and after olfactory experience. We found that at rest, the transcriptomic profiles of mouse olfactory sensory neuron populations are already divergent, specific to the olfactory receptor they express, and are associated with the sequence of these latter. These divergent profiles further evolve in response to the environment, as odorant exposure leads to reprogramming via the modulation of transcription. These findings highlight a broad range of sensory neuron identities that are present at rest and that adapt to the experience of the individual, thus adding to the complexity and flexibility of sensory coding.
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3
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Selective Signal Capture from Multidimensional GPCR Outputs with Biased Agonists: Progress Towards Novel Drug Development. Mol Diagn Ther 2022; 26:383-396. [PMID: 35595932 PMCID: PMC9276727 DOI: 10.1007/s40291-022-00592-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2022] [Indexed: 11/03/2022]
Abstract
G protein coupled receptors (GPCRs) are a superfamily of transmembrane-spanning receptors that are activated by multiple endogenous ligands and are the most common target for agonist or antagonist therapeutics across a broad spectrum of diseases. Initial characterization within the superfamily suggested that a receptor activated a single intracellular pathway, depending on the G protein to which it coupled. However, it has become apparent that a given receptor can activate multiple different pathways, some being therapeutically desirable, while others are neutral or promote deleterious signaling. The activation of pathways that limit effectiveness of a primary pathway or promote unwanted signals has led to abandonment of some GPCRs as drug targets. However, it is now recognized that the conformation of the receptor in its ligand-bound state can be altered by the structure of the agonist or antagonist to achieve pathway selectivity, a property termed biased signaling. Biased ligands could dramatically expand the number of novel drugs acting at GPCRs for new indications. However, the field struggles with the complexity and uncertainty of these structure-functions relationships. In this review we define the theoretical underpinnings of the biased effect, discuss the methods for measuring bias, and the pitfalls that can lead to incorrect assignments of bias. Using the recent elucidation of a β2-adrenergic receptor agonist that is biased in favor of Gs coupling over β-arrestin binding, we provide an example of how large libraries of compounds that are impartial to preconceived notions of agonist binding can be utilized to discover pathway-specific agonists. In this case, an agonist that lacks tachyphylaxis for the treatment of obstructive lung diseases was uncovered, with a structure that was distinctly different from other agonists. We show how biased characteristics were ascertained analytically, and how molecular modeling and simulations provide a structural basis for a restricted signaling repertoire.
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4
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Atomic force microscopy-single-molecule force spectroscopy unveils GPCR cell surface architecture. Commun Biol 2022; 5:221. [PMID: 35273337 PMCID: PMC8913689 DOI: 10.1038/s42003-022-03162-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/14/2022] [Indexed: 01/10/2023] Open
Abstract
G protein-coupled receptors (GPCRs) form the largest family of cell surface receptors. Despite considerable insights into their pharmacology, the GPCR architecture at the cell surface still remains largely unexplored. Herein, we present the specific unfolding of different GPCRs at the surface of living mammalian cells by atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS). Mathematical analysis of the GPCR unfolding distances at resting state revealed the presence of different receptor populations relying on distinct oligomeric states which are receptor-specific and receptor expression-dependent. Moreover, we show that the oligomer size dictates the receptor spatial organization with nanoclusters of high-order oligomers while lower-order complexes spread over the whole cell surface. Finally, the receptor activity reshapes both the oligomeric populations and their spatial arrangement. These results add an additional level of complexity to the GPCR pharmacology until now considered to arise from a single receptor population at the cell surface. Atomic force microscopy-based single molecule force spectroscopy reveals the unfolding of G-protein coupled receptors on the surface of living mammalian cells.
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5
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Viewing rare conformations of the β 2 adrenergic receptor with pressure-resolved DEER spectroscopy. Proc Natl Acad Sci U S A 2020; 117:31824-31831. [PMID: 33257561 DOI: 10.1073/pnas.2013904117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The β2 adrenergic receptor (β2AR) is an archetypal G protein coupled receptor (GPCR). One structural signature of GPCR activation is a large-scale movement (ca. 6 to 14 Å) of transmembrane helix 6 (TM6) to a conformation which binds and activates a cognate G protein. The β2AR exhibits a low level of agonist-independent G protein activation. The structural origin of this basal activity and its suppression by inverse agonists is unknown but could involve a unique receptor conformation that promotes G protein activation. Alternatively, a conformational selection model proposes that a minor population of the canonical active receptor conformation exists in equilibrium with inactive forms, thus giving rise to basal activity of the ligand-free receptor. Previous spin-labeling and fluorescence resonance energy transfer experiments designed to monitor the positional distribution of TM6 did not detect the presence of the active conformation of ligand-free β2AR. Here we employ spin-labeling and pressure-resolved double electron-electron resonance spectroscopy to reveal the presence of a minor population of unliganded receptor, with the signature outward TM6 displacement, in equilibrium with inactive conformations. Binding of inverse agonists suppresses this population. These results provide direct structural evidence in favor of a conformational selection model for basal activity in β2AR and provide a mechanism for inverse agonism. In addition, they emphasize 1) the importance of minor populations in GPCR catalytic function; 2) the use of spin-labeling and variable-pressure electron paramagnetic resonance to reveal them in a membrane protein; and 3) the quantitative evaluation of their thermodynamic properties relative to the inactive forms, including free energy, partial molar volume, and compressibility.
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6
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Kondrashov A, Mohd Yusof NAN, Hasan A, Goulding J, Kodagoda T, Hoang DM, Vo NTN, Melarangi T, Dolatshad N, Gorelik J, Hill SJ, Harding SE, Denning C. CRISPR/Cas9-mediated generation and analysis of N terminus polymorphic models of β 2AR in isogenic hPSC-derived cardiomyocytes. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 20:39-53. [PMID: 33335946 PMCID: PMC7733025 DOI: 10.1016/j.omtm.2020.10.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 10/20/2020] [Indexed: 11/16/2022]
Abstract
During normal- and patho-physiological situations, the behavior of the beta2-adrenoreceptor (β2AR) is influenced by polymorphic variants. The functional impact of such polymorphisms has been suggested from data derived from genetic association studies, in vitro experiments with primary cells, and transgenic overexpression models. However, heterogeneous genetic background and non-physiological transgene expression levels confound interpretation, leading to conflicting mechanistic conclusions. To overcome these limitations, we used CRISPR/Cas9 gene editing technology in human pluripotent stem cells (hPSCs) to create a unique suite of four isogenic homozygous variants at amino acid positions 16(G/R) and 27(G/Q), which reside in the N terminus of the β2AR. By producing cardiomyocytes from these hPSC lines, we determined that at a functional level β2AR signaling dominated over β1AR . Examining changes in beat rates and responses to isoprenaline, Gi coupling, cyclic AMP (cAMP) production, downregulation, and desensitization indicated that responses were often heightened for the GE variant, implying differential dominance of both polymorphic location and amino acid substitution. This finding was corroborated, since GE showed hypersensitivity to doxorubicin-induced cardiotoxicity relative to GQ and RQ variants. Thus, understanding the effect of β2AR polymorphisms on cardiac response to anticancer therapy may provide a route for personalized medicine and facilitate immediate clinical impact.
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Affiliation(s)
- Alexander Kondrashov
- Division of Cancer and Stem Cells, University of Nottingham Biodiscovery Institute, University Park, Nottingham NG7 2RD, UK.,Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Midlands, UK
| | - Nurul A N Mohd Yusof
- Division of Cancer and Stem Cells, University of Nottingham Biodiscovery Institute, University Park, Nottingham NG7 2RD, UK
| | - Alveera Hasan
- National Heart and Lung Institute, Imperial College, London W12 0NN, UK
| | - Joëlle Goulding
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Midlands, UK.,Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK
| | | | - Duc M Hoang
- Division of Cancer and Stem Cells, University of Nottingham Biodiscovery Institute, University Park, Nottingham NG7 2RD, UK
| | - Nguyen T N Vo
- Division of Cancer and Stem Cells, University of Nottingham Biodiscovery Institute, University Park, Nottingham NG7 2RD, UK
| | - Tony Melarangi
- Division of Cancer and Stem Cells, University of Nottingham Biodiscovery Institute, University Park, Nottingham NG7 2RD, UK
| | - Nazanin Dolatshad
- National Heart and Lung Institute, Imperial College, London W12 0NN, UK
| | - Julia Gorelik
- National Heart and Lung Institute, Imperial College, London W12 0NN, UK
| | - Stephen J Hill
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Midlands, UK.,Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Sian E Harding
- National Heart and Lung Institute, Imperial College, London W12 0NN, UK
| | - Chris Denning
- Division of Cancer and Stem Cells, University of Nottingham Biodiscovery Institute, University Park, Nottingham NG7 2RD, UK
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7
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Michel MC, Michel-Reher MB, Hein P. A Systematic Review of Inverse Agonism at Adrenoceptor Subtypes. Cells 2020; 9:E1923. [PMID: 32825009 PMCID: PMC7564766 DOI: 10.3390/cells9091923] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/16/2020] [Accepted: 08/18/2020] [Indexed: 12/18/2022] Open
Abstract
As many, if not most, ligands at G protein-coupled receptor antagonists are inverse agonists, we systematically reviewed inverse agonism at the nine adrenoceptor subtypes. Except for β3-adrenoceptors, inverse agonism has been reported for each of the adrenoceptor subtypes, most often for β2-adrenoceptors, including endogenously expressed receptors in human tissues. As with other receptors, the detection and degree of inverse agonism depend on the cells and tissues under investigation, i.e., they are greatest when the model has a high intrinsic tone/constitutive activity for the response being studied. Accordingly, they may differ between parts of a tissue, for instance, atria vs. ventricles of the heart, and within a cell type, between cellular responses. The basal tone of endogenously expressed receptors is often low, leading to less consistent detection and a lesser extent of observed inverse agonism. Extent inverse agonism depends on specific molecular properties of a compound, but inverse agonism appears to be more common in certain chemical classes. While inverse agonism is a fascinating facet in attempts to mechanistically understand observed drug effects, we are skeptical whether an a priori definition of the extent of inverse agonism in the target product profile of a developmental candidate is a meaningful option in drug discovery and development.
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Affiliation(s)
- Martin C. Michel
- Department of Pharmacology, Johannes Gutenberg University, 55131 Mainz, Germany;
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8
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Luqman A, Muttaqin MZ, Yulaipi S, Ebner P, Matsuo M, Zabel S, Tribelli PM, Nieselt K, Hidayati D, Götz F. Trace amines produced by skin bacteria accelerate wound healing in mice. Commun Biol 2020; 3:277. [PMID: 32483173 PMCID: PMC7264277 DOI: 10.1038/s42003-020-1000-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/08/2020] [Indexed: 12/20/2022] Open
Abstract
Certain skin bacteria are able to convert aromatic amino acids (AAA) into trace amines (TA) that act as neuromodulators. Since the human skin and sweat contain a comparatively high content of AAA one can expect that such bacteria are able to produce TA on our skin. Here we show that TA-producing Staphylococcus epidermidis strains expressing SadA are predominant on human skin and that TA accelerate wound healing. In wounded skin, keratinocytes produce epinephrine (EPI) that leads to cell motility inhibition by β2-adrenergic receptor (β2-AR) activation thus delay wound healing. As β2-AR antagonists, TA and dopamine (DOP) abrogate the effect of EPI thus accelerating wound healing both in vitro and in a mouse model. In the mouse model, the S. epidermidis wild type strain accelerates wound healing compared to its ΔsadA mutant. Our study demonstrates that TA-producing S. epidermidis strains present on our skin might be beneficial for wound healing.
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Affiliation(s)
- Arif Luqman
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, D-72076, Tübingen, Germany
- Biology Department, Institut Teknologi Sepuluh Nopember, 60111, Surabaya, Indonesia
- Generasi Biologi Indonesia (Genbinesia) Foundation, 61171, Gresik, Indonesia
| | - Muhammad Zainul Muttaqin
- Generasi Biologi Indonesia (Genbinesia) Foundation, 61171, Gresik, Indonesia
- Aquaculture Department, Universitas Muhammadiyah Gresik, 61121, Gresik, Indonesia
| | - Sumah Yulaipi
- Biology Department, Institut Teknologi Sepuluh Nopember, 60111, Surabaya, Indonesia
| | - Patrick Ebner
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, D-72076, Tübingen, Germany
| | - Miki Matsuo
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, D-72076, Tübingen, Germany
| | - Susanne Zabel
- Center for Bioinformatics Tübingen, University of Tübingen, Sand 14, D-72076, Tübingen, Germany
| | - Paula Maria Tribelli
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, D-72076, Tübingen, Germany
- Departamento de Química Biológica, FCEyN-UBA, Buenos Aires, Argentina
- IQUIBICEN, CONICET, Buenos Aires, Argentina
| | - Kay Nieselt
- Aquaculture Department, Universitas Muhammadiyah Gresik, 61121, Gresik, Indonesia
| | - Dewi Hidayati
- Biology Department, Institut Teknologi Sepuluh Nopember, 60111, Surabaya, Indonesia.
| | - Friedrich Götz
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, D-72076, Tübingen, Germany.
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9
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Lamichhane R, Liu JJ, White KL, Katritch V, Stevens RC, Wüthrich K, Millar DP. Biased Signaling of the G-Protein-Coupled Receptor β 2AR Is Governed by Conformational Exchange Kinetics. Structure 2020; 28:371-377.e3. [PMID: 31978323 DOI: 10.1016/j.str.2020.01.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/11/2019] [Accepted: 01/03/2020] [Indexed: 01/14/2023]
Abstract
G-protein-coupled receptors (GPCRs) mediate a wide range of human physiological functions by transducing extracellular ligand binding events into intracellular responses. GPCRs can activate parallel, independent signaling pathways mediated by G proteins or β-arrestins. Whereas "balanced" agonists activate both pathways equally, "biased" agonists dominantly activate one pathway, which is of interest for designing GPCR-targeting drugs because it may mitigate undesirable side effects. Previous studies demonstrated that β-arrestin activation is associated with transmembrane helix VII (TM VII) of GPCRs. Here, single-molecule fluorescence spectroscopy with the β2-adrenergic receptor (β2AR) in the ligand-free state showed that TM VII spontaneously fluctuates between one inactive and one active-like conformation. The presence of the β-arrestin-biased agonist isoetharine prolongs the dwell time of TM VII in the active-like conformation compared with the balanced agonist formoterol, suggesting that ligands can induce signaling bias by modulating the kinetics of receptor conformational exchange.
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Affiliation(s)
- Rajan Lamichhane
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jeffrey J Liu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Kate L White
- Departments of Biological Sciences and Chemistry, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Childs Way, MC3502, Los Angeles, CA 90089, USA
| | - Vsevolod Katritch
- Departments of Biological Sciences and Chemistry, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Childs Way, MC3502, Los Angeles, CA 90089, USA
| | - Raymond C Stevens
- Departments of Biological Sciences and Chemistry, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Childs Way, MC3502, Los Angeles, CA 90089, USA
| | - Kurt Wüthrich
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA; Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - David P Millar
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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10
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Islas JF, Abbasgholizadeh R, Dacso C, Potaman VN, Navran S, Bond RA, Iyer D, Birla R, Schwartz RJ. β-Adrenergic stimuli and rotating suspension culture enhance conversion of human adipogenic mesenchymal stem cells into highly conductive cardiac progenitors. J Tissue Eng Regen Med 2020; 14:306-318. [PMID: 31821703 DOI: 10.1002/term.2994] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 11/08/2019] [Accepted: 11/19/2019] [Indexed: 12/26/2022]
Abstract
Clinical trials using human adipogenic mesenchymal stem cells (hAdMSCs) for the treatment of cardiac diseases have shown improvement in cardiac function and were proven safe. However, hAdMSCs do not convert efficiently into cardiomyocytes (CMs) or vasculature. Thus, reprogramming hAdMSCs into myocyte progenitors may fare better in future investigations. To reprogramme hAdMSCs into electrically conductive cardiac progenitor cells, we pioneered a three-step reprogramming strategy that uses proven MESP1/ETS2 transcription factors, β-adrenergic and hypoxic signalling induced in three-dimensional (3D) cardiospheres. In Stage 1, ETS2 and MESP1 activated NNKX2.5, TBX5, MEF2C, dHAND, and GATA4 during the conversion of hAdMSCs into cardiac progenitor cells. Next, in Stage 2, β2AR activation repositioned cardiac progenitors into de novo immature conductive cardiac cells, along with the appearance of RYR2, CAV2.1, CAV3.1, NAV1.5, SERCA2, and CX45 gene transcripts and displayed action potentials. In Stage 3, electrical conduction that was fostered by 3D cardiospheres formed in a Synthecon®, Inc. rotating bioreactor induced the appearance of hypoxic genes: HIF-1α/β, PCG 1α/β, and NOS2, which coincided with the robust activation of adult contractile genes including MLC2v, TNNT2, and TNNI3, ion channel genes, and the appearance of hyperpolarization-activated and cyclic nucleotide-gated channels (HCN1-4). Conduction velocities doubled to ~200 mm/s after hypoxia and doubled yet again after dissociation of the 3D cell clusters to ~400 mm/s. By comparison, normal conduction velocities within working ventricular myocytes in the whole heart range from 0.5 to 1 m/s. Epinephrine stimulation of stage 3 cardiac cells in patches resulted in an increase in amplitude of the electrical wave, indicative of conductive cardiac cells. Our efficient protocol that converted hAdMSCs into highly conductive cardiac progenitors demonstrated the potential utilization of stage 3 cells for tissue engineering applications for cardiac repair.
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Affiliation(s)
- Jose Francisco Islas
- Texas Heart Institute, Texas Medical Center, Houston, TX.,Departamento de Bioquímica y Medicina Molecular, Faculta de Medicina, Universidad Autónoma de Nuevo León, Monterrey, Mexico
| | | | - Clifford Dacso
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Texas Medical Center, Houston, TX
| | | | | | - Richard A Bond
- College of Pharmacy, Science and Engineering Research Center, University of Houston, Houston, TX
| | - Dinakar Iyer
- Department of Biology and Biochemistry, University of Houston, Houston, TX
| | - Ravi Birla
- Department of Biomedical Engineering, University of Houston, Houston, TX
| | - Robert J Schwartz
- Texas Heart Institute, Texas Medical Center, Houston, TX.,Department of Biology and Biochemistry, University of Houston, Houston, TX
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11
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Shiina S, Kanemura A, Suzuki C, Yamaki F, Obara K, Chino D, Tanaka Y. β-Adrenoceptor subtypes and cAMP role in adrenaline- and noradrenaline-induced relaxation in the rat thoracic aorta. J Smooth Muscle Res 2019. [PMID: 29540622 PMCID: PMC5863045 DOI: 10.1540/jsmr.54.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Object We identified the β-adrenoceptor (β-AR) subtypes responsible for the
relaxant responses to adrenaline (AD) and noradrenaline (NA) in the rat thoracic aorta and
examined the role of cAMP which is involved in these relaxant responses.
Methods The effects of β-AR antagonists or the adenylyl cyclase inhibitor
SQ 22,536 on AD- and NA-induced relaxant responses in phenylephrine-induced contraction
and increases in cAMP levels were examined in isolated, endothelium-denuded rat thoracic
aorta segments. Results AD-induced relaxation was completely suppressed by
propranolol (10−7 M) or by ICI-118,551 (10−8 M) plus atenolol
(10−6 M), and was also very strongly inhibited by ICI-118,551
(10−8 M) alone. AD (10−5 M) increased tissue cAMP levels by
approximately 1.9-fold compared with that in non-stimulated aortic tissue, but did not
significantly increase cAMP levels in the presence of ICI-118,551 (10−8 M) or
SQ 22,536 (10−4 M). AD-induced relaxation was strongly suppressed by SQ 22,536
(10−4 M). NA-induced relaxation was almost completely suppressed by atenolol
(10−6 M) plus ICI-118,551 (10−8 M) although it was hardly affected
by ICI-118,551 (10−8 M) alone. NA (10−5 M) increased tissue cAMP
levels by approximately 2.2-fold compared with that in non-stimulated aortic tissue, but
did not significantly increase cAMP levels in the presence of atenolol (10−6 M)
or SQ 22,536 (10−4 M). NA-induced relaxation was strongly suppressed by SQ
22,536 (10−4 M). Conclusion In rat thoracic aorta, AD- and
NA-induced relaxations, which are both strongly dependent on increased tissue cAMP levels,
are mainly mediated through β2- and β1-adrenoceptors
respectively.
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Affiliation(s)
- Shunsuke Shiina
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
| | - Ayaka Kanemura
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
| | - Chihiro Suzuki
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
| | - Fumiko Yamaki
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
| | - Keisuke Obara
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
| | - Daisuke Chino
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan.,Department of Pharmacotherapy, Faculty of Pharmaceutical Sciences, Nihon Pharmaceutical University, 10281 Komuro, Ina-machi, Kita-Adachi-gun, Saitama 362-0806, Japan
| | - Yoshio Tanaka
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan
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12
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Mersfelder TL, Shiltz DL. β-Blockers and the Rate of Chronic Obstructive Pulmonary Disease Exacerbations. Ann Pharmacother 2019; 53:1249-1258. [PMID: 31271049 DOI: 10.1177/1060028019862322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Objective: To review the rate of exacerbations relative to β-blocker use in patients with chronic obstructive pulmonary disease (COPD). Data Sources: A MEDLINE search (1953 to May 2019) was performed using the search terms beta-blockers, chronic obstructive pulmonary disease, and exacerbations. An EMBASE search was also performed using the search terms chronic obstructive lung disease and beta adrenergic receptor blocking agents (1970 to May 2019). References from the review of literature citations were also identified. Study Selection and Data Extraction: English-language studies assessing COPD exacerbations in patients prescribed a β-blocker were included. Any article not addressing exacerbations was excluded. Data Synthesis: A total of 15 articles were included; 7 articles showed no change, 1 provided mixed results, and 7 indicated a significant decrease in COPD exacerbations in a variety of exacerbation severities. Two of the studies differentiated between cardioselective and noncardioselective β-blockers. Relevance to Patient Care and Clinical Practice: This work represents an initial assessment of the use of β-blockers to reduce COPD exacerbations. The findings raise the question if β-blockers should be used more frequently in patients with COPD. Conclusions: Based on the limited number of studies that address β-blocker use in COPD, it appears that exacerbations are not increased and may be decreased. A randomized, placebo-controlled trial is in progress to possibly provide more definitive answers to this question. Until the trial is complete, β-blockers should not be withheld in COPD patients who have concurrent cardiovascular conditions, especially where there is a mortality benefit.
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Affiliation(s)
| | - Dane L Shiltz
- Ferris State University College of Pharmacy, Grand Rapids, MI, USA
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13
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Cleveland KH, Liang S, Chang A, Huang KM, Chen S, Guo L, Huang Y, Andresen BT. Carvedilol inhibits EGF-mediated JB6 P+ colony formation through a mechanism independent of adrenoceptors. PLoS One 2019; 14:e0217038. [PMID: 31107911 PMCID: PMC6527222 DOI: 10.1371/journal.pone.0217038] [Citation(s) in RCA: 11] [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: 03/12/2019] [Accepted: 05/02/2019] [Indexed: 01/13/2023] Open
Abstract
Carvedilol is reported to prevent cancers in humans and animal models. However, a molecular mechanism has yet to be established, and the extent to which other β-blockers are chemopreventive remains relatively unknown. A comparative pharmacological approach was utilized with the expectation that a mechanism of action could be devised. JB6 Cl 41-5a (JB6 P+) murine epidermal cells were used to elucidate the chemopreventative properties of β-blockers, as JB6 P+ cells recapitulate in vivo tumor promotion and chemoprevention. The initial hypothesis was that β-blockers that are GRK/β-arrestin biased agonists, like carvedilol, are chemopreventive. Sixteen β-blockers of different classes, isoproterenol, and HEAT HCl were individually co-administered with epidermal growth factor (EGF) to JB6 P+ cells to examine the chemopreventative properties of each ligand. Cytotoxicity was examined to ensure that the anti-transformation effects of each ligand were not due to cellular growth inhibition. Many of the examined β-blockers suppressed EGF-induced JB6 P+ cell transformation in a non-cytotoxic and concentration-dependent manner. However, the IC50 values are high for the most potent inhibitors (243, 326, and 431 nM for carvedilol, labetalol, and alprenolol, respectively) and there is no correlation between pharmacological properties and inhibition of transformation. Therefore, the role of α1- and β2-adrenergic receptors (AR) was examined by standard competition assays and shRNA targeting β2-ARs, the only β-AR expressed in JB6 P+ cells. The results reveal that pharmacological inhibition of α1- and β2-ARs and genetic knockdown of β2-ARs did not abrogate carvedilol-mediated inhibition of EGF-induced JB6 P+ cell transformation. Furthermore, topical administration of carvedilol protected mice from UV-induced skin damage, while genetic ablation of β2-ARs increased carvedilol-mediated effects. Therefore, the prevailing hypothesis that the chemopreventive property of carvedilol is mediated through β-ARs is not supported by this data.
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Affiliation(s)
- Kristan H. Cleveland
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, California, United States of America
| | - Sherry Liang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, California, United States of America
| | - Andy Chang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, California, United States of America
| | - Kevin M. Huang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, California, United States of America
| | - Si Chen
- Division of Biochemical Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, United States of America
| | - Lei Guo
- Division of Biochemical Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas, United States of America
| | - Ying Huang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, California, United States of America
- * E-mail: (YH); (BTA)
| | - Bradley T. Andresen
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, California, United States of America
- * E-mail: (YH); (BTA)
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14
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Golovko AI, Ivanov MB, Golovko ES, Dolgo-Saburov VB, Zatsepin EP. The Neurochemical Mechanisms of the Pharmacological Activities of Inverse Agonists of the Benzodiazepine Binding Site. NEUROCHEM J+ 2018. [DOI: 10.1134/s1819712418030042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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15
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Abstract
G-protein-coupled receptors (GPCRs) are a large group of membrane-bound receptor proteins that are involved in a plethora of diverse processes (e.g., vision, hormone response). In mammals, and particularly in humans, GPCRs are involved in many signal transduction pathways and, as such, are heavily studied for their immense pharmaceutical potential. Indeed, a large fraction of drugs target various GPCRs, and drug-development is often aimed at GPCRs. Therefore, understanding the activation of GPCRs is a challenge of major importance both from fundamental and practical considerations. And yet, despite the remarkable progress in structural understanding, we still do not have a translation of the structural information to an energy-based picture. Here we use coarse-grained (CG) modeling to chart the free-energy landscape of the activation process of the β-2 adrenergic receptor (β2AR) as a representative GPCR. The landscape provides the needed tool for analyzing the processes that lead to activation of the receptor upon binding of the ligand (adrenaline) while limiting constitutive activation. Our results pave the way to better understand the biological mechanisms of action of the β2AR and GPCRs, from a physical chemistry point of view rather than simply by observing the receptor's behavior physiologically.
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16
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Chen X, Meroueh M, Mazur G, Rouse E, Hundal KS, Stamatkin CW, Obukhov AG. Phenylephrine, a common cold remedy active ingredient, suppresses uterine contractions through cAMP signalling. Sci Rep 2018; 8:11666. [PMID: 30076382 PMCID: PMC6076280 DOI: 10.1038/s41598-018-30094-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 07/24/2018] [Indexed: 12/17/2022] Open
Abstract
Regulation of uterine contractility is an important aspect of women’s health. Phenylephrine, a selective agonist of the α1-adrenoceptor and a potent smooth muscle constrictor, is widely used in women even during pregnancy to relieve cold-related symptoms, to treat postpartum haemorrhoid, and during routine eye exams. We performed isometric tension recordings to investigate the effect of phenylephrine on mouse uterine contractility. Phenylephrine decreased spontaneous and oxytocin-induced contractions in non-pregnant mouse uterine rings and strips with an IC50 of ~1 μM. Prazosin, an inhibitor of α1-adrenoceptor, did not prevent phenylephrine-mediated relaxations. Conversely, ICI118551, an antagonist of β2-adrenoceptors, inhibited phenylephrine relaxation. In the presence of ICI118551, high concentrations (>30 μM) of phenylephrine caused mouse uterine contractions, suggesting that β-adrenoceptor-mediated inhibition interferes with the phenylephrine contractile potential. Phenylephrine-dependent relaxation was reduced in the uterus of pregnant mice. We used primary mouse and human uterine smooth muscle cells (M/HUSMC) to establish the underlying mechanisms. Phenylephrine stimulated large increases in intracellular cAMP in M/HUSMCs. These cAMP transients were decreased when HUSMCs were cultured in the presence of oestrogen and progesterone to mimic the pregnancy milieu. Thus, phenylephrine is a strong relaxant in the non-pregnant mouse uterus, but exhibits diminished effect in the pregnant uterus.
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Affiliation(s)
- Xingjuan Chen
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA
| | - Marya Meroueh
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA
| | - Gabriela Mazur
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA
| | - Evan Rouse
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA.,Advanced Testing Laboratory, Cincinnati, OH, USA
| | - Karmjot Singh Hundal
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA
| | - Christopher W Stamatkin
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA.,Covance Greenfield Laboratories, Greenfield, IN, USA
| | - Alexander G Obukhov
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, USA.
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17
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Insight into partial agonism by observing multiple equilibria for ligand-bound and G s-mimetic nanobody-bound β 1-adrenergic receptor. Nat Commun 2017; 8:1795. [PMID: 29176642 PMCID: PMC5702606 DOI: 10.1038/s41467-017-02008-y] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 11/01/2017] [Indexed: 11/12/2022] Open
Abstract
A complex conformational energy landscape determines G-protein-coupled receptor (GPCR) signalling via intracellular binding partners (IBPs), e.g., Gs and β-arrestin. Using 13C methyl methionine NMR for the β1-adrenergic receptor, we identify ligand efficacy-dependent equilibria between an inactive and pre-active state and, in complex with Gs-mimetic nanobody, between more and less active ternary complexes. Formation of a basal activity complex through ligand-free nanobody–receptor interaction reveals structural differences on the cytoplasmic receptor side compared to the full agonist-bound nanobody-coupled form, suggesting that ligand-induced variations in G-protein interaction underpin partial agonism. Significant differences in receptor dynamics are observed ranging from rigid nanobody-coupled states to extensive μs-to-ms timescale dynamics when bound to a full agonist. We suggest that the mobility of the full agonist-bound form primes the GPCR to couple to IBPs. On formation of the ternary complex, ligand efficacy determines the quality of the interaction between the rigidified receptor and an IBP and consequently the signalling level. β1-adrenergic receptors are expressed in cardiac tissue and stimulated by the sympathetic nervous system. Here, the authors use NMR spectroscopy to unravel the conformational diversity upon β1-adrenergic receptor activation and provide structural insights into partial agonism and basal activity.
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18
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Oxysterol, 5α-cholestan-3-one, modulates a contractile response to β2-adrenoceptor stimulation in the mouse atria: Involvement of NO signaling. Life Sci 2017; 188:131-140. [DOI: 10.1016/j.lfs.2017.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 08/29/2017] [Accepted: 09/04/2017] [Indexed: 11/22/2022]
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19
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Nakashima N, Nakashima K, Nakayama T, Takaku A, Kanamori R. Dual expression of constitutively active Gα s-protein-coupled receptors differentially establishes the resting activity of the cAMP-gated HCN2 channel in a single compartment. Biochem Biophys Res Commun 2017; 494:76-81. [PMID: 29054409 DOI: 10.1016/j.bbrc.2017.10.082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 10/16/2017] [Indexed: 11/24/2022]
Abstract
The hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) channel is a major subtype of the HCN channel family expressed in the nervous system that sets the membrane potential, regulates cell excitability and senses changes in the extracellular environment. Neurons express various Gαs-protein-coupled receptors (GPCRs), many of which show ligand-independent constitutive activity. These membrane-bound proteins are expressed in various subcellular compartments of neurons. Therefore, some proportion of HCN2 channels opens in response to the basal cAMP pool size produced by constitutively active GPCRs. Here, we employed an exogenous HEK293 expression system and voltage-clamp patch-clamp recordings to investigate basal HCN2 channel activity in the presence of two GPCRs with diverse basal activities in a single compartment. We utilized the β2-adrenoceptor (β2AR) together with odorant receptors (ORs), as both GPCR families are known to show strong basal activity. Consequently, β2AR alone strongly enhanced the activity of HCN2 channels, and co-expression of ORs further diversified the HCN2 channel activity, which was totally abolished by an adenylate cyclase inhibitor. Thus, we conclude that the dual expression of constitutively active GPCRs establishes the diverse range of the basal cAMP pool size in resting cells through mutual additive or suppressive interactions, even in the absence of external stimulation.
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Affiliation(s)
- Noriyuki Nakashima
- Division of Integrated Autonomic Function, Department of Physiology, School of Medicine, Kurume University, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan; Department of Physiology and Neurobiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
| | - Kie Nakashima
- Department of Physiology and Neurobiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan; Laboratory of Developmental Neurobiology, Graduate School of Biostudies, Kyoto University, Yoshida Hon-machi, Kyoto 606-8501, Japan
| | - Takeo Nakayama
- Department of Physiology and Neurobiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Akiko Takaku
- Department of Physiology and Neurobiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan; Medical Scientist Training Program, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
| | - Ryosuke Kanamori
- Department of Physiology and Neurobiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan
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20
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Single-molecule analysis of ligand efficacy in β 2AR-G-protein activation. Nature 2017; 547:68-73. [PMID: 28607487 PMCID: PMC5502743 DOI: 10.1038/nature22354] [Citation(s) in RCA: 225] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 04/07/2017] [Indexed: 12/18/2022]
Abstract
G protein-coupled receptor (GPCR)-mediated signal transduction is central to human physiology and disease intervention, yet the molecular mechanisms responsible for ligand-dependent signaling responses remain poorly understood. In Class A GPCRs, receptor activation and G protein coupling entail outward movements of transmembrane segment 6 (TM6). Using single-molecule Fluorescence Resonance Energy Transfer (smFRET) imaging, we examine TM6 motions in the β2 adrenergic receptor (β2AR) upon exposure to orthosteric ligands with different efficacies, in the absence and presence of the Gs heterotrimer. We show that partial and full agonists affect TM6 motions in a manner that differentially regulates the rate at which GDP-bound β2AR-Gs complexes are formed and the efficiency of nucleotide exchange leading to Gs activation. These data also reveal transient nucleotide-bound β2AR-Gs species distinct from known structures and single-molecule perspectives on the allosteric link between ligand and nucleotide binding pockets that shed new light on the G protein activation mechanism.
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21
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Bondar A, Lazar J. The G protein G i1 exhibits basal coupling but not preassembly with G protein-coupled receptors. J Biol Chem 2017; 292:9690-9698. [PMID: 28438833 DOI: 10.1074/jbc.m116.768127] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/21/2017] [Indexed: 11/06/2022] Open
Abstract
The Gi/o protein family transduces signals from a diverse group of G protein-coupled receptors (GPCRs). The observed specificity of Gi/o-GPCR coupling and the high rate of Gi/o signal transduction have been hypothesized to be enabled by the existence of stable associates between Gi/o proteins and their cognate GPCRs in the inactive state (Gi/o-GPCR preassembly). To test this hypothesis, we applied the recently developed technique of two-photon polarization microscopy (2PPM) to Gαi1 subunits labeled with fluorescent proteins and four GPCRs: the α2A-adrenergic receptor, GABAB, cannabinoid receptor type 1 (CB1R), and dopamine receptor type 2. Our experiments with non-dissociating mutants of fluorescently labeled Gαi1 subunits (exhibiting impaired dissociation from activated GPCRs) showed that 2PPM is capable of detecting GPCR-G protein interactions. 2PPM experiments with non-mutated fluorescently labeled Gαi1 subunits and α2A-adrenergic receptor, GABAB, or dopamine receptor type 2 receptors did not reveal any interaction between the Gi1 protein and the non-stimulated GPCRs. In contrast, non-stimulated CB1R exhibited an interaction with the Gi1 protein. Further experiments revealed that this interaction is caused solely by CB1R basal activity; no preassembly between CB1R and the Gi1 protein could be observed. Our results demonstrate that four diverse GPCRs do not preassemble with non-active Gi1 However, we also show that basal GPCR activity allows interactions between non-stimulated GPCRs and Gi1 (basal coupling). These findings suggest that Gi1 interacts only with active GPCRs and that the well known high speed of GPCR signal transduction does not require preassembly between G proteins and GPCRs.
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Affiliation(s)
- Alexey Bondar
- From the Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, 37333 Nove Hrady,
| | - Josef Lazar
- From the Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, 37333 Nove Hrady.,the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 16610 Prague, and.,the Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic
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22
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Rovati GE, Capra V, Shaw VS, Malik RU, Sivaramakrishnan S, Neubig RR. The DRY motif and the four corners of the cubic ternary complex model. Cell Signal 2017; 35:16-23. [PMID: 28347873 DOI: 10.1016/j.cellsig.2017.03.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/24/2017] [Indexed: 12/14/2022]
Abstract
Recent structural data on GPCRs using a variety of spectroscopic approaches suggest that GPCRs adopt a dynamic conformational landscape, with ligands stabilizing subsets of these states to activate one or more downstream signaling effectors. A key outstanding question posed by this emerging dynamic structural model of GPCRs is what states, active, inactive, or intermediate are captured by the numerous crystal structures of GPCRs complexed with a variety of agonists, partial agonists, and antagonists. In the early nineties the discovery of inverse agonists and constitutive activity led to the idea that the active receptor state (R⁎) is an intrinsic property of the receptor itself rather than of the RG complex, eventually leading to the formulation of the cubic ternary complex model (CTC). Here, by a careful analysis of a series of data obtained with a number of mutants of the highly conserved E/DRY motif, we show evidences for the existence of all the receptor states theorized by the CTC, four 'uncoupled (R, R⁎ and HR and HR⁎), and, consequently four 'coupled' (RG, R⁎G, HRG and HR⁎G). The E/DRY motif located at the cytosolic end of transmembrane helix III of Class A GPCRs has been widely studied and analyzed because it forms a network of interactions believed to lock receptors in the inactive conformation (R), and, thus, to play a key role in receptor activation. Our conclusions are supported by recent crystal and NMR spectra, as well as by results obtained with two prototypical GPCRs using a new FRET technology that de-couples G protein binding to the receptor from signal transduction. Thus, despite its complexity and limitations, we propose that the CTC is a useful framework to reconcile pharmacological, biochemical and structural data.
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Affiliation(s)
- G Enrico Rovati
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy.
| | - Valérie Capra
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy; Department of Health Science, University of Milan, Milano, Italy.
| | - Vincent S Shaw
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA.
| | - Rabia U Malik
- Department of Genetics, Cell Biology & Development, College of Biological Sciences, University of Minnesota Twin Cities, Minneapolis, MN, USA.
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology & Development, College of Biological Sciences, University of Minnesota Twin Cities, Minneapolis, MN, USA.
| | - Richard R Neubig
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA.
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23
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Liu G, Xue D, Yang J, Wang J, Liu X, Huang W, Li J, Long YQ, Tan W, Zhang A. Design, Synthesis, and Pharmacological Evaluation of 2-(2,5-Dimethyl-5,6,7,8-tetrahydroquinolin-8-yl)-N-aryl Propanamides as Novel Smoothened (Smo) Antagonists. J Med Chem 2016; 59:11050-11068. [PMID: 27736063 DOI: 10.1021/acs.jmedchem.6b01247] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A series of novel Smo antagonists were developed either by directly incorporating the basic skeleton of the natural product artemisinin or by first breaking artemisinin into structurally simpler and stable intermediates and then reconstructing into diversified heterocyclic derivatives, equipped with a Smo-targeting bullet. 2-(2,5-Dimethyl-5,6,7,8-tetrahydroquinolin-8-yl)-N-arylpropanamide 65 was identified as the most potent, with an IC50 value of 9.53 nM against the Hh signaling pathway. Complementary mechanism studies confirmed that 65 inhibits Hh signaling pathway by targeting Smo and shares the same binding site as that of the tool drug cyclopamine. Meanwhile, 65 has a good plasma exposure and an acceptable oral bioavailability. Dose-dependent antiproliferative effects were observed in ptch+/-;p53-/- medulloblastoma cells, and significant tumor growth inhibitions were achieved for 65 in the ptch+/-;p53-/- medulloblastoma allograft model.
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Affiliation(s)
- Gang Liu
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica (SIMM), University of Chinese Academy of Sciences , 555 Zuchongzhi Lu, Building 3, Room 426, Shanghai 201203, China
| | - Ding Xue
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica (SIMM), University of Chinese Academy of Sciences , 555 Zuchongzhi Lu, Building 3, Room 426, Shanghai 201203, China
| | - Jun Yang
- Department of Pharmacology, School of Pharmacy, Fudan University , Shanghai 201203, China
| | - Juan Wang
- Department of Pharmacology, School of Pharmacy, Fudan University , Shanghai 201203, China
| | - Xiaohua Liu
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica (SIMM), University of Chinese Academy of Sciences , 555 Zuchongzhi Lu, Building 3, Room 426, Shanghai 201203, China
| | - Wenjing Huang
- Department of Pharmacology, School of Pharmacy, Fudan University , Shanghai 201203, China
| | - Jie Li
- School of Life Science and Technology, ShanghaiTech University , Shanghai 201210, China
| | - Ya-Qiu Long
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica (SIMM), University of Chinese Academy of Sciences , 555 Zuchongzhi Lu, Building 3, Room 426, Shanghai 201203, China
| | - Wenfu Tan
- Department of Pharmacology, School of Pharmacy, Fudan University , Shanghai 201203, China
| | - Ao Zhang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica (SIMM), University of Chinese Academy of Sciences , 555 Zuchongzhi Lu, Building 3, Room 426, Shanghai 201203, China.,School of Life Science and Technology, ShanghaiTech University , Shanghai 201210, China
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24
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Single-molecule view of basal activity and activation mechanisms of the G protein-coupled receptor β2AR. Proc Natl Acad Sci U S A 2015; 112:14254-9. [PMID: 26578769 DOI: 10.1073/pnas.1519626112] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Binding of extracellular ligands to G protein-coupled receptors (GPCRs) initiates transmembrane signaling by inducing conformational changes on the cytoplasmic receptor surface. Knowledge of this process provides a platform for the development of GPCR-targeting drugs. Here, using a site-specific Cy3 fluorescence probe in the human β2-adrenergic receptor (β2AR), we observed that individual receptor molecules in the native-like environment of phospholipid nanodiscs undergo spontaneous transitions between two distinct conformational states. These states are assigned to inactive and active-like receptor conformations. Individual receptor molecules in the apo form repeatedly sample both conformations, with a bias toward the inactive conformation. Experiments in the presence of drug ligands show that binding of the full agonist formoterol shifts the conformational distribution in favor of the active-like conformation, whereas binding of the inverse agonist ICI-118,551 favors the inactive conformation. Analysis of single-molecule dwell-time distributions for each state reveals that formoterol increases the frequency of activation transitions, while also reducing the frequency of deactivation events. In contrast, the inverse agonist increases the frequency of deactivation transitions. Our observations account for the high level of basal activity of this receptor and provide insights that help to rationalize, on the molecular level, the widely documented variability of the pharmacological efficacies among GPCR-targeting drugs.
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25
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Sato T, Baker J, Warne T, Brown GA, Leslie AGW, Congreve M, Tate CG. Pharmacological Analysis and Structure Determination of 7-Methylcyanopindolol-Bound β1-Adrenergic Receptor. Mol Pharmacol 2015; 88:1024-34. [PMID: 26385885 DOI: 10.1124/mol.115.101030] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/17/2015] [Indexed: 11/22/2022] Open
Abstract
Comparisons between structures of the β1-adrenergic receptor (AR) bound to either agonists, partial agonists, or weak partial agonists led to the proposal that rotamer changes of Ser(5.46), coupled to a contraction of the binding pocket, are sufficient to increase the probability of receptor activation. (RS)-4-[3-(tert-butylamino)-2-hydroxypropoxy]-1H-indole-2-carbonitrile (cyanopindolol) is a weak partial agonist of β1AR and, based on the hypothesis above, we predicted that the addition of a methyl group to form 4-[(2S)-3-(tert-butylamino)-2-hydroxypropoxy]-7-methyl-1H-indole-2-carbonitrile (7-methylcyanopindolol) would dramatically reduce its efficacy. An eight-step synthesis of 7-methylcyanopindolol was developed and its pharmacology was analyzed. 7-Methylcyanopindolol bound with similar affinity to cyanopindolol to both β1AR and β2AR. As predicted, the efficacy of 7-methylcyanopindolol was reduced significantly compared with cyanopindolol, acting as a very weak partial agonist of turkey β1AR and an inverse agonist of human β2AR. The structure of 7-methylcyanopindolol-bound β1AR was determined to 2.4-Å resolution and found to be virtually identical to the structure of cyanopindolol-bound β1AR. The major differences in the orthosteric binding pocket are that it has expanded by 0.3 Å in 7-methylcyanopindolol-bound β1AR and the hydroxyl group of Ser(5.46) is positioned 0.8 Å further from the ligand, with respect to the position of the Ser(5.46) side chain in cyanopindolol-bound β1AR. Thus, the molecular basis for the reduction in efficacy of 7-methylcyanopindolol compared with cyanopindolol may be regarded as the opposite of the mechanism proposed for the increase in efficacy of agonists compared with antagonists.
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Affiliation(s)
- Tomomi Sato
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Jillian Baker
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Tony Warne
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Giles A Brown
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Andrew G W Leslie
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Miles Congreve
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Christopher G Tate
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
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26
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Al-Sawalha N, Pokkunuri I, Omoluabi O, Kim H, Thanawala VJ, Hernandez A, Bond RA, Knoll BJ. Epinephrine Activation of the β2-Adrenoceptor Is Required for IL-13-Induced Mucin Production in Human Bronchial Epithelial Cells. PLoS One 2015; 10:e0132559. [PMID: 26161982 PMCID: PMC4498766 DOI: 10.1371/journal.pone.0132559] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 06/17/2015] [Indexed: 12/16/2022] Open
Abstract
Mucus hypersecretion by airway epithelium is a hallmark of inflammation in allergic asthma and results in airway narrowing and obstruction. Others have shown that administration a TH2 cytokine, IL-13 is sufficient to cause mucus hypersecretion in vivo and in vitro. Asthma therapy often utilizes β2-adrenoceptor (β2AR) agonists, which are effective acutely as bronchodilators, however chronic use may lead to a worsening of asthma symptoms. In this study, we asked whether β2AR signaling in normal human airway epithelial (NHBE) cells affected mucin production in response to IL-13. This cytokine markedly increased mucin production, but only in the presence of epinephrine. Mucin production was blocked by ICI-118,551, a preferential β2AR antagonist, but not by CGP-20712A, a preferential β1AR antagonist. Constitutive β2AR activity was not sufficient for IL-13 induced mucin production and β-agonist-induced signaling is required. A clinically important long-acting β-agonist, formoterol, was as effective as epinephrine in potentiating IL-13 induced MUC5AC transcription. IL-13 induced mucin production in the presence of epinephrine was significantly reduced by treatment with selective inhibitors of ERK1/2 (FR180204), p38 (SB203580) and JNK (SP600125). Replacement of epinephrine with forskolin + IBMX resulted in a marked increase in mucin production in NHBE cells in response to IL-13, and treatment with the inhibitory cAMP analogue Rp-cAMPS decreased mucin levels induced by epinephrine + IL-13. Our findings suggest that β2AR signaling is required for mucin production in response to IL-13, and that mitogen activated protein kinases and cAMP are necessary for this effect. These data lend support to the notion that β2AR-agonists may contribute to asthma exacerbations by increasing mucin production via activation of β2ARs on epithelial cells.
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Affiliation(s)
- Nour Al-Sawalha
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Indira Pokkunuri
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Ozozoma Omoluabi
- Department of Biology and Biochemistry, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Hosu Kim
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Vaidehi J. Thanawala
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Adrian Hernandez
- Department of Biology and Biochemistry, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Richard A. Bond
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
- Department of Biology and Biochemistry, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
| | - Brian J. Knoll
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
- Department of Biology and Biochemistry, University of Houston, 4800 Calhoun Road, Houston, Texas, 77204, United States of America
- * E-mail:
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27
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Nguyen MN, Kiriazis H, Ruggiero D, Gao XM, Su Y, Jian A, Han LP, McMullen JR, Du XJ. Spontaneous ventricular tachyarrhythmias in β2-adrenoceptor transgenic mice in relation to cardiac interstitial fibrosis. Am J Physiol Heart Circ Physiol 2015; 309:H946-57. [PMID: 26116714 DOI: 10.1152/ajpheart.00405.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 06/26/2015] [Indexed: 12/21/2022]
Abstract
Myocardial fibrosis is regarded as a pivotal proarrhythmic substrate, but there have been no comprehensive studies showing a correlation between the severity of fibrosis and ventricular tachyarrhythmias (VTAs). Our purpose was to document this relationship in a transgenic (TG) strain of mice with fibrotic cardiomyopathy. TG mice with cardiac overexpression of β2-adrenoceptors (β2-AR mice) and non-TG (NTG) littermates were studied at 4-12 mo of age. VTA was quantified by ECG telemetry. The effect of pharmacological blockade of β2-ARs on VTA was examined. Myocardial collagen content was determined by hydroxyproline assay. NTG and TG mice displayed circadian variation in heart rate, which was higher in TG mice than in NTG mice (P <0.05). Frequent spontaneous ventricular ectopic beats (VEBs) and ventricular tachycardia (VT) were prominent in TG mice but not present in NTG mice. The frequency of VEB and VT episodes in TG mice increased with age (P < 0.01). Ventricular collagen content was greater in TG mice than in NTG mice (P <0.001) and correlated with age (r = 0.71, P < 0.01). The number of VEBs or VT episodes correlated with age (r = 0.83 and r = 0.73) and the content of total or cross-linked collagen (r = 0.62∼0.66, all P <0.01). While having no effect in younger β2-TG mice, β2-AR blockade reduced the frequency of VTA in old β2-TG mice with more severe fibrosis. In conclusion, β2-TG mice exhibit interstitial fibrosis and spontaneous onset of VTA, becoming more severe with aging. The extent of cardiac fibrosis is a major determinant for both the frequency of VTA and proarrhythmic action of β2-AR activation.
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Affiliation(s)
- My-Nhan Nguyen
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Helen Kiriazis
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Diego Ruggiero
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; University of Milan, Milan, Italy
| | - Xiao-Ming Gao
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Yidan Su
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Anne Jian
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Li-Ping Han
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; WenZhou Medical University, WenZhou, China; and
| | - Julie R McMullen
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; Central Clinical School, Monash University, Melbourne, Victoria, Australia; Department of Physiology, Monash University, Melbourne, Australia
| | - Xiao-Jun Du
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; Central Clinical School, Monash University, Melbourne, Victoria, Australia;
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28
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Wang J, Peng Y, Liu Y, Yang J, Huang M, Tan W. AT-101 inhibits hedgehog pathway activity and cancer growth. Cancer Chemother Pharmacol 2015; 76:461-9. [PMID: 26113054 DOI: 10.1007/s00280-015-2812-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/15/2015] [Indexed: 02/06/2023]
Abstract
PURPOSE AT-101 is considered as a putative pan-inhibitor of anti-apoptotic Bcl-2 family protein members acting as a BH3 mimetic. It is currently being investigated in phase I/II clinical trial in various types of cancers. In this study, using a series of in vitro and in vivo assays, we evaluated the effect of AT-101 on the hedgehog (Hh) signaling pathway activity and its anticancer ability. RESULTS We found that AT-101 obviously blocked the Hh signaling pathway activity in response to ShhN-conditioned medium (ShhN CM). This inhibitory effect, to some extent, displayed selectivity against Hh signaling pathway. Furthermore, we identified that AT-101 potentially acted on smoothened (Smo) by sharing the same binding site with cyclopamine, a classical Hh signaling pathway inhibitor. Taking advantage of the patch+/-; p53-/- mouse medulloblastoma model, we observed that AT-101 significantly suppressed the Hh-driven medulloblastoma growth in vitro and in vivo. CONCLUSIONS This study demonstrates that AT-101 significantly and selectively inhibits Hh pathway activity by potentially targeting Smo and consequently suppresses the growth of Hh-driven cancer. Therefore, this study reveals a novel molecular mechanism responsible for the anticancer action of AT-101 and contributes to the further development of AT-101 as an anticancer drug.
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Affiliation(s)
- Juan Wang
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai, 201203, People's Republic of China
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29
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Xu Q, Jennings NL, Sim K, Chang L, Gao XM, Kiriazis H, Lee YY, Nguyen MN, Woodcock EA, Zhang YY, El-Osta A, Dart AM, Du XJ. Pathological hypertrophy reverses β2-adrenergic receptor-induced angiogenesis in mouse heart. Physiol Rep 2015; 3:3/3/e12340. [PMID: 25780088 PMCID: PMC4393171 DOI: 10.14814/phy2.12340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
β-adrenergic activation and angiogenesis are pivotal for myocardial function but the link between both events remains unclear. The aim of this study was to explore the cardiac angiogenesis profile in a mouse model with cardiomyocyte-restricted overexpression of β2-adrenoceptors (β2-TG), and the effect of cardiac pressure overload. β2-TG mice had heightened cardiac angiogenesis, which was essential for maintenance of the hypercontractile phenotype seen in this model. Relative to controls, cardiomyocytes of β2-TGs showed upregulated expression of vascular endothelial growth factor (VEGF), heightened phosphorylation of cAMP-responsive-element-binding protein (CREB), and increased recruitment of phospho-CREB, CREB-binding protein (CBP), and p300 to the VEGF promoter. However, when hearts were subjected to pressure overload by transverse aortic constriction (TAC), angiogenic signaling in β2-TGs was inhibited within 1 week after TAC. β2-TG hearts, but not controls, exposed to pressure overload for 1–2 weeks showed significant increases from baseline in phosphorylation of Ca2+/calmodulin-dependent kinase II (CaMKIIδ) and protein expression of p53, reduction in CREB phosphorylation, and reduced abundance of phospho-CREB, p300 and CBP recruited to the CREB-responsive element (CRE) site of VEGF promoter. These changes were associated with reduction in both VEGF expression and capillary density. While non-TG mice with TAC developed compensatory hypertrophy, (2-TGs exhibited exaggerated hypertrophic growth at week-1 post-TAC, followed by LV dilatation and reduced fractional shortening measured by serial echocardiography. In conclusion, angiogenesis was enhanced by the cardiomyocyte (2AR/CREB/VEGF signaling pathway. Pressure overload rapidly inhibited this signaling, likely as a consequence of activated CaMKII and p53, leading to impaired angiogenesis and functional decompensation.
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Affiliation(s)
- Qi Xu
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Nicole L Jennings
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Kenneth Sim
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Lisa Chang
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Xiao-Ming Gao
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Helen Kiriazis
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Ying Ying Lee
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - My-Nhan Nguyen
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | | | - You-Yi Zhang
- Institute of Cardiovascular Sciences, Peking University Health Science Center, Beijing, China
| | - Assam El-Osta
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Anthony M Dart
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Alfred Heart Centre, the Alfred Hospital, Melbourne, Victoria, Australia Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Xiao-Jun Du
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Central Clinical School, Monash University, Melbourne, Victoria, Australia
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30
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Woo AYH, Song Y, Zhu W, Xiao RP. Advances in receptor conformation research: the quest for functionally selective conformations focusing on the β2-adrenoceptor. Br J Pharmacol 2015; 172:5477-88. [PMID: 25537131 DOI: 10.1111/bph.13049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 12/14/2014] [Indexed: 01/14/2023] Open
Abstract
Seven-transmembrane receptors, also called GPCRs, represent the largest class of drug targets. Upon ligand binding, a GPCR undergoes conformational rearrangement and thereby changes its interaction with effector proteins including the cognate G-proteins and the multifunctional adaptor proteins, β-arrestins. These proteins, by initiating distinct signal transduction mechanisms, mediate one or several functional responses. Recently, the concept of ligand-directed GPCR signalling, also called functional selectivity or biased agonism, has been proposed to explain the phenomenon that chemically diverse ligands exhibit different efficacies towards the different signalling pathways of a single GPCR, and thereby act as functionally selective or 'biased' ligands. Current concepts support the notion that ligand-specific GPCR conformations are the basis of ligand-directed signalling. Multiple studies using fluorescence spectroscopy, X-ray crystallography, mass spectroscopy, nuclear magnetic resonance spectroscopy, single-molecule force spectroscopy and other techniques have provided the evidence to support this notion. It is anticipated that these techniques will ultimately help elucidate the structural basis of ligand-directed GPCR signalling at a precision meaningful for structure-based drug design and how a specific ligand molecular structure induces a unique receptor conformation leading to biased signalling. In this review, we will summarize recent advances in experimental techniques applied in the study of functionally selective GPCR conformations and breakthrough data obtained in these studies particularly those of the β2-adrenoceptor.
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Affiliation(s)
- Anthony Yiu-Ho Woo
- Institute of Molecular Medicine, Centre for Life Sciences, Peking University, Beijing, China.,Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Ying Song
- Institute of Molecular Medicine, Centre for Life Sciences, Peking University, Beijing, China
| | - Weizhong Zhu
- Department of Pharmacology, Nantong University School of Pharmacy, Nantong, China
| | - Rui-Ping Xiao
- Institute of Molecular Medicine, Centre for Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing, China
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31
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Roosterman D. Agonist-dependent and -independent dopamine-1-like receptor signalling differentially regulates downstream effectors. FEBS J 2014; 281:4792-804. [PMID: 25154512 DOI: 10.1111/febs.13018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 07/25/2014] [Accepted: 08/21/2014] [Indexed: 12/17/2022]
Abstract
De-regulation of energy metabolism by the dopaminergic system is linked to neurological diseases such as schizophrenia and bipolar disorder. Inverse agonists are thought to be more beneficial in treating neurological diseases than neutral antagonists, but only limited experimental data are available regarding the impact of constitutive signalling on energy metabolism. The aim of the present study was to assess the impact of constitutive dopamine-1 receptor (D1R) and dopamine-5 receptor (D5R) signalling on downstream targets in transiently and stably transfected HEK293T cells. The high constitutive activity of D5R was accompanied by increased Na(+)/H(+) exchanger (NHE) activity and accelerated glucose degradation due to increased transcription and translation of the Na, K-ATPase-α3 and NHE-2. Chronic treatment with an agonist increased the mRNA levels of the α2 Na,K-ATPase, NHE-2 and NHE-3. Constitutive D5R activation of a cAMP response element-based reporter was regulated by G protein-coupled receptor kinase 2, but this did not affect the cell-surface abundance of the receptor. Our data suggest that constitutive and agonist-induced activity of D5R differentially regulates the activity and expression of proteins.
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32
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Tang W, Strachan RT, Lefkowitz RJ, Rockman HA. Allosteric modulation of β-arrestin-biased angiotensin II type 1 receptor signaling by membrane stretch. J Biol Chem 2014; 289:28271-83. [PMID: 25170081 DOI: 10.1074/jbc.m114.585067] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
It has recently been appreciated that the angiotensin II type 1 receptor (AT1R), a prototypic member of the G protein-coupled receptor superfamily, also functions as a mechanosensor. Specifically, mechanical stretch activates the AT1R to promote downstream signaling mediated exclusively by the multifunctional scaffold protein, β-arrestin, in a manner consistent with previously identified β-arrestin-biased ligands. However, the ligand-independent mechanism by which mechanical stretch promotes β-arrestin-biased signaling remains unknown. Implicit in the concept of biased agonism (i.e. the ability of an agonist to activate a subset of receptor-mediated signaling pathways) is the notion that distinct active conformations of the receptor mediate differential activation of signaling pathways. Here we determined whether mechanical stretch stabilizes distinct β-arrestin-activating conformations of the AT1R by using β-arrestin2-biased agonists as conformational probes in pharmacological and biophysical assays. When tested at cells expressing the AT1R fused to β-arrestin (AT1R-β-arrestin2), we found that osmotic stretch increased the binding affinity and potency of the β-arrestin-biased agonist TRV120023, with no effect on the balanced agonist AngII. In addition, the effect of osmotic stretch on ERK activation was markedly augmented in cells expressing the AT1R-β-arrestin2 fusion compared with the wild type AT1R and completely blocked in cells expressing the AT1R-Gq fusion. Biophysical experiments with an intramolecular BRET β-arrestin2 biosensor revealed that osmotic stretch and TRV120023 activate AT1Rs to stabilize β-arrestin2 active conformations that differ from those stabilized by the AT1R activated by angiotensin II. Together, these data support a novel ligand-independent mechanism whereby mechanical stretch allosterically stabilizes specific β-arrestin-biased active conformations of the AT1R and has important implications for understanding pathophysiological AT1R signaling.
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Affiliation(s)
- Wei Tang
- From the Departments of Medicine
| | - Ryan T Strachan
- From the Departments of Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710
| | - Robert J Lefkowitz
- From the Departments of Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710
| | - Howard A Rockman
- From the Departments of Medicine, Cell Biology, and Molecular Genetics and Microbiology, and
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33
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Shonberg J, Lopez L, Scammells PJ, Christopoulos A, Capuano B, Lane JR. Biased Agonism at G Protein-Coupled Receptors: The Promise and the Challenges-A Medicinal Chemistry Perspective. Med Res Rev 2014; 34:1286-330. [DOI: 10.1002/med.21318] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jeremy Shonberg
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University (Parkville Campus); Parkville Victoria Australia
| | - Laura Lopez
- Drug Discovery Biology; Monash Institute of Pharmaceutical Sciences; Monash University (Parkville Campus); Parkville Victoria Australia
| | - Peter J. Scammells
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University (Parkville Campus); Parkville Victoria Australia
| | - Arthur Christopoulos
- Drug Discovery Biology; Monash Institute of Pharmaceutical Sciences; Monash University (Parkville Campus); Parkville Victoria Australia
| | - Ben Capuano
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University (Parkville Campus); Parkville Victoria Australia
| | - J. Robert Lane
- Drug Discovery Biology; Monash Institute of Pharmaceutical Sciences; Monash University (Parkville Campus); Parkville Victoria Australia
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34
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Thanawala VJ, Forkuo GS, Stallaert W, Leff P, Bouvier M, Bond R. Ligand bias prevents class equality among beta-blockers. Curr Opin Pharmacol 2014; 16:50-7. [PMID: 24681351 DOI: 10.1016/j.coph.2014.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/26/2014] [Accepted: 03/03/2014] [Indexed: 01/14/2023]
Abstract
β-Blockers are used for a wide range of diseases from hypertension to glaucoma. In some diseases/conditions all β-blockers are effective, while in others only certain subgroups are therapeutically beneficial. The best-documented example for only a subset of β-blockers showing clinical efficacy is in heart failure, where members of the class have ranged from completely ineffective, to drugs of choice for treating the disease. Similarly, β-blockers were tested in murine asthma models and two pilot clinical studies. A different subset was found to be effective for this clinical indication. These findings call into question the current system of classifying these drugs. To consider 'β-blockers', as a single class is misleading when considering their rigorous pharmacological definition and their appropriate clinical application.
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Affiliation(s)
- Vaidehi J Thanawala
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX, USA
| | - Gloria S Forkuo
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX, USA
| | - Wayne Stallaert
- Department of Biochemistry, Université de Montréal, Montréal, Quebec, Canada; Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada
| | - Paul Leff
- Consultant in Pharmacology, Cheshire, UK
| | - Michel Bouvier
- Department of Biochemistry, Université de Montréal, Montréal, Quebec, Canada; Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada
| | - Richard Bond
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX, USA.
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35
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Grailer JJ, Haggadone MD, Sarma JV, Zetoune FS, Ward PA. Induction of M2 regulatory macrophages through the β2-adrenergic receptor with protection during endotoxemia and acute lung injury. J Innate Immun 2014; 6:607-18. [PMID: 24642449 DOI: 10.1159/000358524] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 01/11/2014] [Indexed: 01/10/2023] Open
Abstract
The main drivers of acute inflammation are macrophages, which are known to have receptors for catecholamines. Based on their function, macrophages are broadly categorized as having either M1 (proinflammatory) or M2 phenotypes (anti-inflammatory). In this study, we investigated catecholamine-induced alterations in the phenotype of activated macrophages. In the presence of lipopolysaccharide (LPS), mouse peritoneal macrophages acquired an M1 phenotype. However, the copresence of LPS and either epinephrine or norepinephrine resulted in a strong M2 phenotype including high levels of arginase-1 and interleukin-10, and a reduced expression of M1 markers. Furthermore, epinephrine enhanced macrophage phagocytosis and promoted type 2 T-cell responses in vitro, which are known features of M2 macrophages. Analysis of M2 subtype-specific markers indicated that LPS and catecholamine-cotreated macrophages were not alternatively activated but were rather of the regulatory macrophage subtype. Interestingly, catecholamines signaled through the β2-adrenergic receptor but not the canonical cAMP/protein kinase A signaling pathway. Instead, the M2 pathway required an intact phosphoinositol 3-kinase pathway. Blockade of the β2-adrenergic receptor reduced survival and enhanced injury in mouse models of endotoxemia and LPS-induced acute lung injury, respectively. These results demonstrate a role for the β2-adrenergic receptor in promoting the M2 macrophage phenotype.
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Affiliation(s)
- Jamison J Grailer
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Mich., USA
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36
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Gomes AC, Falcão-Pires I, Pires AL, Brás-Silva C, Leite-Moreira AF. Rodent models of heart failure: an updated review. Heart Fail Rev 2013; 18:219-49. [PMID: 22446984 DOI: 10.1007/s10741-012-9305-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Heart failure (HF) is one of the major health and economic burdens worldwide, and its prevalence is continuously increasing. The study of HF requires reliable animal models to study the chronic changes and pharmacologic interventions in myocardial structure and function and to follow its progression toward HF. Indeed, during the past 40 years, basic and translational scientists have used small animal models to understand the pathophysiology of HF and find more efficient ways of preventing and managing patients suffering from congestive HF (CHF). Each species and each animal model has advantages and disadvantages, and the choice of one model over another should take them into account for a good experimental design. The aim of this review is to describe and highlight the advantages and drawbacks of some commonly used HF rodents models, including both non-genetically and genetically engineered models, with a specific subchapter concerning diastolic HF models.
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Affiliation(s)
- A C Gomes
- Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal
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Full and partial agonists of thromboxane prostanoid receptor unveil fine tuning of receptor superactive conformation and G protein activation. PLoS One 2013; 8:e60475. [PMID: 23555978 PMCID: PMC3610872 DOI: 10.1371/journal.pone.0060475] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/26/2013] [Indexed: 01/14/2023] Open
Abstract
The intrahelical salt bridge between E/D3.49 and R3.50 within the E/DRY motif on helix 3 (H3) and the interhelical hydrogen bonding between the E/DRY and residues on H6 are thought to be critical in stabilizing the class A G protein-coupled receptors in their inactive state. Removal of these interactions is expected to generate constitutively active receptors. This study examines how neutralization of E3.49/6.30 in the thromboxane prostanoid (TP) receptor alters ligand binding, basal, and agonist-induced activity and investigates the molecular mechanisms of G protein activation. We demonstrate here that a panel of full and partial agonists showed an increase in affinity and potency for E129V and E240V mutants. Yet, even augmenting the sensitivity to detect constitutive activity (CA) with overexpression of the receptor or the G protein revealed resistance to an increase in basal activity, while retaining fully the ability to cause agonist-induced signaling. However, direct G protein activation measured through bioluminescence resonance energy transfer (BRET) indicates that these mutants more efficiently communicate and/or activate their cognate G proteins. These results suggest the existence of additional constrains governing the shift of TP receptor to its active state, together with an increase propensity of these mutants to agonist-induced signaling, corroborating their definition as superactive mutants. The particular nature of the TP receptor as somehow “resistant” to CA should be examined in the context of its pathophysiological role in the cardiovascular system. Evolutionary forces may have favored regulation mechanisms leading to low basal activity and selected against more highly active phenotypes.
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Abstract
Myocardial contraction occurs when calcium (Ca(2+)) is released from the sarcoplasmic reticulum, binding troponin C and allowing actin and myosin to cross link. Ca(2+) release and uptake is closely regulated by G protein-coupled β-adrenergic receptors through the action of the second messenger cAMP. An increase in cAMP level leads to phosphorylation of key regulatory proteins affecting intracellular Ca(2+) homeostasis. The β-adrenergic receptors themselves are regulated by a set of specific kinases, termed the G-protein-coupled receptor kinases (GRKs). The study of this complex system in vivo has recently been advanced by the development of transgenic and gene-targeted (knockout) mouse models. Combining transgenic technology with sophisticated physiological measurements of cardiac hemodynamics is an extremely powerful approach to the study of myocardial contractility and its regulation. This review focuses on several recent transgenic mouse models that have increased our understanding of the regulation of cardiac contractility.
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Affiliation(s)
- O Ben-Yehuda
- Ori Ben-Yehuda and Howard A. Rockman are at the Division of Cardiology, Department of Medicine, University of California at San Diego, School of Medicine, La Jolla, CA 92093-01613, USA
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Zhang Y, Ye J, Hu L, Zhang S, Zhang SH, Li Y, Kunapuli SP, Ding Z. Increased platelet activation and thrombosis in transgenic mice expressing constitutively active P2Y12. J Thromb Haemost 2012; 10:2149-57. [PMID: 22906019 PMCID: PMC3495164 DOI: 10.1111/j.1538-7836.2012.04894.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND In our previous in vitro study, we reported a constitutively active chimeric P2Y(12) (cP2Y(12)) and found that AR-C78511 is a potent inverse agonist at this receptor. The role of cP2Y(12) in platelet activation and thrombosis is not clear. OBJECTIVES To investigate the physiologic implications of cP2Y(12) for platelet activation and thrombus formation, and to evaluate the antiplatelet activity of AR-C78511 as an inverse agonist. METHODS AND RESULTS We generated transgenic mice conditionally and platelet-specifically expressing cP2Y(12). High-level expression of cP2Y(12) in platelets increased platelet reactivity, as shown by increased platelet aggregation in response to multiple platelet agonists. Moreover, transgenic mice showed a shortened bleeding time, and more rapid and stable thrombus formation in mesenteric artery injured with FeCl(3). The constitutive activity of cP2Y(12) in platelets was confirmed by decreased platelet cAMP levels and constitutive Akt phosphorylation in the absence of agonists. AR-C78511 reversed the cAMP decrease in transgenic mouse platelets, and exhibited a superior antiplatelet effect to that of AR-C69931MX in transgenic mice. CONCLUSIONS These findings further emphasize the importance of P2Y(12) in platelet activation, hemostasis, and thrombosis, as well as the prothrombotic role of the constitutive activity of P2Y(12). Our data also validate the in vivo inverse agonist activity of AR-C78511, and confirm its superior antiplatelet activity over neutral antagonists.
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Affiliation(s)
- Y Zhang
- Key Laboratory of Molecular Medicine, Ministry of Education and Department of Biochemistry and Molecular Biology, Fudan University Shanghai, China
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Shi Q, Hou Y, Hou J, Pan P, Liu Z, Jiang M, Gao J, Bai G. Glycyrrhetic acid synergistically enhances β₂-adrenergic receptor-Gs signaling by changing the location of Gαs in lipid rafts. PLoS One 2012; 7:e44921. [PMID: 23028680 PMCID: PMC3459958 DOI: 10.1371/journal.pone.0044921] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/09/2012] [Indexed: 11/26/2022] Open
Abstract
Glycyrrhetic acid (GA) exerts synergistic anti-asthmatic effects via a β2-adrenergic receptor (β2AR)-mediated pathway. Cholesterol is an important component of the structure and function of lipid rafts, which play critical roles in the β2AR-Gs-adenylate cyclase (AC)-mediated signaling pathway. Owing to the structural similarities between GA and cholesterol, we investigated the possibility that GA enhances β2AR signaling by altering cholesterol distribution. Azide-terminal GA (ATGA) was synthesized and applied to human embryonic kidney 293 (HEK293) cells expressing fusion β2AR, and the electron spin resonance (ESR) technique was utilized. GA was determined to be localized predominantly on membrane and decreased their cholesterol contents. Thus, the fluidity of the hydrophobic region increased but not the polar surface of the cell membrane. The conformations of membrane proteins were also changed. GA further changed the localization of Gαs from lipid rafts to non-raft regions, resulting the binding of β2AR and Gαs, as well as in reduced β2AR internalization. Co-localization of β2AR, Gαs, and AC increased isoproterenol-induced cAMP production and cholesterol reloading attenuated this effect. A speculation wherein GA enhances beta-adrenergic activity by increasing the functional linkage between the subcomponents of the membrane β2AR-protein kinase A (PKA) signaling pathway was proposed. The enhanced efficacy of β2AR agonists by this novel mechanism could prevent tachyphylaxis.
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Affiliation(s)
- Qian Shi
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Yuanyuan Hou
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Jie Hou
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Penwei Pan
- College of Life Sciences, Nankai University, Tianjin, China
| | - Ze Liu
- College of Medicine, Nankai University, Tianjin, China
| | - Min Jiang
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Jie Gao
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Gang Bai
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
- * E-mail:
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41
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Abstract
Adrenergic receptors and their ligands are important regulators of synaptic plasticity and metaplasticity, but the exact mechanisms underlying their action are still poorly understood. Octopamine, the invertebrate homolog of mammalian adrenaline or noradrenaline, plays important roles in modulating behavior and synaptic functions. We previously uncovered an octopaminergic positive-feedback mechanism to regulate structural synaptic plasticity during development and in response to starvation. Under this mechanism, activation of Octß2R autoreceptors by octopamine at octopaminergic neurons initiated a cAMP-dependent cascade that stimulated the development of new synaptic boutons at the Drosophila larval neuromuscular junction (NMJ). However, the regulatory mechanisms that served to brake such positive feedback were not known. Here, we report the presence of an alternative octopamine autoreceptor, Octß1R, with antagonistic functions on synaptic growth. Mutations in octß1r result in the overgrowth of both glutamatergic and octopaminergic NMJs, suggesting that Octß1R is a negative regulator of synaptic expansion. As Octß2R, Octß1R functioned in a cell-autonomous manner at presynaptic motorneurons. However, unlike Octß2R, which activated a cAMP pathway, Octß1R likely inhibited cAMP production through inhibitory Goα. Despite its inhibitory role, Octß1R was required for acute changes in synaptic structure in response to octopamine and for starvation-induced increase in locomotor speed. These results demonstrate the dual action of octopamine on synaptic growth and behavioral plasticity, and highlight the important role of inhibitory influences for normal responses to physiological stimuli.
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Jiang X, Xu C, Wang Y, Gao L, Yan C, Li D, Sun H. β2-adrenoceptor transfection enhances contractile reserve of isolated rat ventricular myocytes exposed to chronic isoprenaline stimulation by improving β1-adrenoceptor responsiveness. J Recept Signal Transduct Res 2012; 32:36-41. [PMID: 22216755 DOI: 10.3109/10799893.2011.610107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONTEXT Heart failure (HF) is a progressive deterioration in heart function associated with overactivity of the sympathetic nervous system. Elevated sympathetic nervous system activity down regulates the β-adrenergic signal system, suppressing β-adrenoceptors (β-ARs)-mediated contractile support in the failing heart. OBJECTIVE We investigated the effects of β(2)-AR gene transfer on shortening amplitude of isolated ventricular myocytes under chronic exposure to isoprenaline (ISO), and further determine the contributions of β(1)-AR and β(2)-AR to the contraction. MATERIALS AND METHODS Cardiomyocytes were isolated from adult rat hearts and then transfected with β(2)-AR gene using an adenovirus vector. Four hours after the infection, cardiomyocytes were treated with ISO for another 24 hours to imitate high levels of circulating catecholamines in HF. Western blotting was performed to measure myocardial protein expression of β(2)-AR. Video-based edge-detection system was used to evaluate basal and ISO-stimulated shortening amplitudes of cardiomyocytes. RESULTS β(2)-AR gene transfer increased β(2)-AR protein content. Chronic ISO stimulation produced a negative inotropic response, whereas acute ISO stimulation showed a positive inotropic response. β(2)-AR gene transfer had no significant effects on shortening amplitude of cardiomyocytes under normal conditions, but enhanced the blunted contraction of cardiomyocytes under pathological conditions induced by chronic ISO stimulation, and the effect was inhibited by β(1)-AR antagonist, CGP 20712A, instead of β(2)-AR antagonist, ICI 118,551. DISCUSSION AND CONCLUSIONS We conclude that β(2)-AR gene transfer in isolated ventricular myocytes under chronic ISO stimulation improves cellular contraction, and the beneficial effects might be mediated by improving β(1)-adrenoceptor responsiveness.
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Affiliation(s)
- XinWei Jiang
- Department of Physiology, Xuzhou Medical College, Xuzhou, China
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Gamaleddin I, Guranda M, Goldberg SR, Le Foll B. The selective anandamide transport inhibitor VDM11 attenuates reinstatement of nicotine seeking behaviour, but does not affect nicotine intake. Br J Pharmacol 2012; 164:1652-60. [PMID: 21501143 DOI: 10.1111/j.1476-5381.2011.01440.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE The endocannabinoid system appears to play a pivotal role in mediating the rewarding and reinforcing effects of nicotine. Recent studies have shown that the inhibition of fatty acid amide hydrolase (FAAH) attenuates reinstatement of nicotine-seeking induced by nicotine priming and nicotine-associated cues. FAAH hydrolyses the endogenous endocannabinoid anandamide, as well as other non-cannabinoid ligands such as oleoylethanolamide (OEA) and palmitoylethanolamide (PEA). As OEA and PEA can attenuate both nicotine-taking and nicotine-seeking behaviour, the specific role of anandamide remains unclear. In this study, we have tested the selective anadamide uptake inhibitor, VDM11, which elevates anandamide levels without affecting levels of OEA/PEA, on nicotine-taking and nicotine-seeking behaviour. EXPERIMENTAL APPROACH We used a nicotine intravenous self-administration model in rats to assess the effect of VDM11, given i.p., on nicotine taking using fixed and progressive ratio schedules of reinforcement as well as on reinstatement of nicotine-seeking induced by nicotine priming and nicotine-associated cues. KEY RESULTS VDM11 did not affect levels of responding for nicotine under fixed-ratio and progressive-ratio schedules of reinforcement. In contrast, VDM11 dose-dependently attenuated reinstatement of nicotine-seeking behaviour induced by nicotine-associated cues and nicotine priming. CONCLUSIONS AND IMPLICATIONS These results indicate that ligands elevating anandamide levels could have therapeutic value for preventing relapse into nicotine-seeking behaviour and should be tested in humans trying to quit smoking.
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Affiliation(s)
- Islam Gamaleddin
- Translational Addiction Research Laboratory, Centre for Addiction and Mental Health, Toronto, Canada
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44
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Abstract
β-adrenergic receptor (βAR) stimulation by the sympathetic nervous system or circulating catecholamines is broadly involved in peripheral blood circulation, metabolic regulation, muscle contraction, and central neural activities. In the heart, acute βAR stimulation serves as the most powerful means to regulate cardiac output in response to a fight-or-flight situation, whereas chronic βAR stimulation plays an important role in physiological and pathological cardiac remodeling.There are three βAR subtypes, β(1)AR, β(2)AR and β(3)AR, in cardiac myocytes. Over the past two decades, we systematically investigated the molecular and cellular mechanisms underlying the different even opposite functional roles of β(1)AR and β(2)AR subtypes in regulating cardiac structure and function, with keen interest in the development of novel therapies based on our discoveries. We have made three major discoveries, including (1) dual coupling of β(2)AR to G(s) and G(i) proteins in cardiomyocytes, (2) cardioprotection by β(2)AR signaling in improving cardiac function and myocyte viability, and (3) PKA-independent, CaMKII-mediated β(1)AR apoptotic and maladaptive remodeling signaling in the heart. Based on these discoveries and salutary effects of β(1)AR blockade on patients with heart failure, we envision that activation of β(2)AR in combination with clinically used β(1)AR blockade should provide a safer and more effective therapy for the treatment of heart failure.
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Nguyen LP, Singh B, Okulate AA, Alfaro VY, Tuvim MJ, Dickey BF, Bond RA. Complementary anti-inflammatory effects of a β-blocker and a corticosteroid in an asthma model. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2012; 385:203-10. [PMID: 21964666 DOI: 10.1007/s00210-011-0692-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 09/05/2011] [Indexed: 02/03/2023]
Abstract
Glucocorticosteroids are the mainstay treatment for chronic asthma; however, adverse effects can limit their usefulness. We previously determined in experimental asthma that chronic administration of β₂-adrenoceptor inverse agonists reduced airway hyperresponsiveness and indexes of inflammation. However, the effect of co-administration of glucocorticosteroids with β₂-adrenoceptor inverse agonists is unknown. Therefore, we evaluated the anti-inflammatory effect of co-administration of dexamethasone, a glucocorticosteroid, and nadolol, a β₂-inverse agonist, in a murine asthma model. We measured eosinophils and cytokines in bronchoalveolar lavage fluid and mucin content in epithelial cells after exposure to different concentrations of dexamethasone and nadolol. Dexamethasone was administered for 3 days and nadolol for 24 days prior to ovalbumin challenge. Both drugs were continued during five daily intranasal challenges with ovalbumin. Independent administration of dexamethasone (0.4 mg/kg/day) or nadolol (25 ppm) reduced bronchoalveolar lavage eosinophils by 58% and 36%, respectively (P < 0.05). Co-administration of both drugs yielded an additive reduction in eosinophils (81%, P < 0.05). Co-administration of both drugs (dexamethasone 0.4 mg/kg/day and nadolol 25 ppm) also yielded a greater reduction in mucin volume density (83%) than either drug alone (18% for dexamethasone and 62% for nadolol) and greater than high-dose dexamethasone (71%) alone (P < 0.05). Similarly, co-administration of both drugs (dexamethasone 0.4 mg/kg/day and nadolol 25 ppm) yielded an additive effect on the reduction of type 2 cytokines in bronchoalveolar lavage fluid equivalent to the administration of a 10-fold higher dose of dexamethasone. In Summary, the simultaneous administration of a glucocorticosteroid and a β₂-adrenoceptor inverse agonist was more effective at reducing indexes of airway inflammation than either drug given alone; suggesting nadolol may possess "glucocorticoid-sparing" properties.
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Affiliation(s)
- Long P Nguyen
- Department of Pulmonary Medicine, MD Anderson Cancer Center, University of Texas, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Stallaert W, Christopoulos A, Bouvier M. Ligand functional selectivity and quantitative pharmacology at G protein-coupled receptors. Expert Opin Drug Discov 2011; 6:811-25. [DOI: 10.1517/17460441.2011.586691] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Lamyel F, Warnken-Uhlich M, Seemann WK, Mohr K, Kostenis E, Ahmedat AS, Smit M, Gosens R, Meurs H, Miller-Larsson A, Racké K. The β2-subtype of adrenoceptors mediates inhibition of pro-fibrotic events in human lung fibroblasts. Naunyn Schmiedebergs Arch Pharmacol 2011; 384:133-45. [PMID: 21603974 DOI: 10.1007/s00210-011-0655-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 05/09/2011] [Indexed: 01/10/2023]
Abstract
Fibrosis is part of airway remodelling observed in bronchial asthma and COPD. Pro-fibrotic activity of lung fibroblasts may be suppressed by β-adrenoceptor activation. We aimed, first, to characterise the expression pattern of β-adrenoceptor subtypes in human lung fibroblasts and, second, to probe β-adrenoceptor signalling with an emphasis on anti-fibrotic actions. Using reverse transcription PCR, messenger RNA (mRNA) encoding β(2)-adrenoceptors was detected in MRC-5, HEL-299 and primary human lung fibroblasts, whereas transcripts for β(1)- and β(3)-adrenoceptors were not found. Real-time measurement of dynamic mass redistribution in MRC-5 cells revealed β-agonist-induced G(s)-signalling. Proliferation of MRC-5 cells (determined by [(3)H]-thymidine incorporation) was significantly inhibited by β-agonists including the β(2)-selective agonist formoterol (-logIC(50), 10.2) and olodaterol (-logIC(50), 10.6). Formoterol's effect was insensitive to β(1)-antagonism (GCP 20712, 3 μM), but sensitive to β(2)-antagonism (ICI 118,551; apparent, pA (2), 9.6). Collagen synthesis in MRC-5 cells (determined by [(3)H]-proline incorporation) was inhibited by β-agonists including formoterol (-logIC(50), 10.0) and olodaterol (-logIC(50), 10.3) in a β(2)-blocker-sensitive manner. α-Smooth muscle actin, a marker of myo-fibroblast differentiation, was down-regulated at the mRNA and the protein level by about 50% following 24 and 48 h exposure to 1 nM formoterol, a maximally active concentration. In conclusion, human lung fibroblasts exclusively express β(2)-adrenoceptors and these mediate inhibition of various markers of pro-fibrotic cellular activity. Under clinical conditions, anti-fibrotic actions may accompany the therapeutic effect of long-term β(2)-agonist treatment of bronchial asthma and COPD.
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Affiliation(s)
- F Lamyel
- Institute of Pharmacology & Toxicology, University of Bonn, Bonn, Germany
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Vošahlíková M, Svoboda P. The influence of monovalent cations on trimeric G protein G(i)1α activity in HEK293 cells stably expressing DOR-G(i)1α (Cys(351)-Ile(351)) fusion protein. Physiol Res 2011; 60:541-7. [PMID: 21401297 DOI: 10.33549/physiolres.932096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The effect of monovalent cations on trimeric G protein G(i)1α was measured at equimolar concentration of chloride anion in pertussis-toxin (PTX)-treated HEK293 cells stably expressing PTX-insensitive DOR- G(i)1α (Cys(351)-Ile(351)) fusion protein by high-affinity [(35)S]GTPgammaS binding assay. The high basal level of binding was detected in absence of DOR agonist and monovalent ions and this high level was inhibited with the order of: Na(+) > K(+) > Li(+). The first significant inhibition was detected at 1 mM NaCl. The inhibition by monovalent ions was reversed by increasing concentrations of DOR agonist DADLE. The maximum DADLE response was also highest for sodium and decreased in the order of: Na(+) > K(+) ~ Li(+). Our data indicate i) an inherently high activity of trimeric G protein G(i)1α when expressed within DOR- G(i)1α fusion protein and determined in the absence of monovalent cations, ii) preferential sensitivity of DOR- G(i)1alpha to sodium as far as maximum of agonist response is involved.
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Affiliation(s)
- M Vošahlíková
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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49
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Abstract
Increasing numbers of compounds, previously classified as antagonists, were shown to inhibit this spontaneous or constitutive receptor activity, instead of leave it unaffected as expected for a formal antagonist. In addition, some other antagonists did not have any effect by themselves, but prevented the inhibition of constitutive activity induced by thought-to-be antagonists. These thought-to-be antagonists with negative efficacy are now known as "inverse agonists." Inverse agonism at βAR has been evidenced for both subtypes in wild-type GPCRs systems and in engineered systems with high constitutive activity. It is important to mention that native systems are of particular importance for analyzing the in vivo relevance of constitutive activity because these systems have physiological expression levels of target receptors. Studies of inverse agonism of β blockers in physiological setting have also evidenced that pathophysiological conditions can affect pharmacodynamic properties of these ligands. To date, hundreds of clinically well-known drugs have been tested and classified for this property. Prominent examples include the beta-blockers propranolol, alprenolol, pindolol, and timolol used for treating hypertension, angina pectoris, and arrhythmia that act on the β₂ARs, metoprolol, and bisoprolol used for treating hypertension, coronary heart disease, and arrhythmias by acting on β₁ARs. Inverse agonists seem to be useful in the treatment of chronic disease characterized by harmful effects resulting from β₁AR and β₂AR overactivation, such as heart failure and asthma, respectively.
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Affiliation(s)
- Carlos A Taira
- Cátedra de Farmacología, Instituto de Fisiopatología y Bioquímica Clínica, Universidad de Buenos Aires, CONICET, Junín 956, Buenos Aires, Argentina
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50
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Sanz-Rosa D. Los receptores β adrenérgicos en la enfermedad cardiovascular. HIPERTENSION Y RIESGO VASCULAR 2011. [DOI: 10.1016/j.hipert.2011.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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