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Chung YK, Chan HY, Lee TY, Wong YH. Inhibition of adenylyl cyclase by GTPase-deficient Gα i is mechanistically different from that mediated by receptor-activated Gα i. Cell Commun Signal 2024; 22:218. [PMID: 38581012 PMCID: PMC10996109 DOI: 10.1186/s12964-024-01572-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Accepted: 03/16/2024] [Indexed: 04/07/2024] Open
Abstract
Signal transduction through G protein-coupled receptors (GPCRs) has been a major focus in cell biology for decades. Numerous disorders are associated with GPCRs that utilize Gi proteins to inhibit adenylyl cyclase (AC) as well as regulate other effectors. Several early studies have successfully defined the AC-interacting domains of several members of Gαi by measuring the loss of activity upon homologous replacements of putative regions of constitutive active Gαi mutants. However, whether such findings can indeed be translated into the context of a receptor-activated Gαi have not been rigorously verified. To address this issue, an array of known and new chimeric mutations was introduced into GTPase-deficient Q204L (QL) and R178C (RC) mutants of Gαi1, followed by examinations on their ability to inhibit AC. Surprisingly, most chimeras failed to abolish the constitutive activity brought on by the QL mutation, while some were able to eliminate the inhibitory activity of RC mutants. Receptor-mediated inhibition of AC was similarly observed in the same chimeric constructs harbouring the pertussis toxin (PTX)-resistant C351I mutation. Moreover, RC-bearing loss-of-function chimeras appeared to be hyper-deactivated by endogenous RGS protein. Molecular docking revealed a potential interaction between AC and the α3/β5 loop of Gαi1. Subsequent cAMP assays support a cooperative action of the α3/β5 loop, the α4 helix, and the α4/β6 loop in mediating AC inhibition by Gαi1-i3. Our results unveiled a notable functional divergence between constitutively active mutants and receptor-activated Gαi1 to inhibit AC, and identified a previously unknown AC-interacting domain of Gαi subunits. These results collectively provide valuable insights on the mechanism of AC inhibition in the cellular environment.
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Affiliation(s)
- Yin Kwan Chung
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, 04103, Leipzig, Germany
| | - Ho Yung Chan
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China
| | - Tung Yeung Lee
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yung Hou Wong
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China.
- State Key Laboratory of Molecular Neuroscience, and the Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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Liu Z, Hou S, He P. Detection of Ligand-Induced Receptor Kinase and Signaling Component Phosphorylation with Mn 2+-Phos-Tag SDS-PAGE. Methods Mol Biol 2024; 2731:205-214. [PMID: 38019436 DOI: 10.1007/978-1-0716-3511-7_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Plasma membrane-resident receptor kinases (RKs) are crucial for plants to sense endogenous and exogenous signals in regulating growth, development, and stress response. Upon perception of ligands by the extracellular domain, RKs are usually activated by auto- and/or trans-phosphorylation of the cytoplasmic kinase domain, which in turn phosphorylates downstream substrates to relay the signaling. Therefore, monitoring ligand-induced in vivo phosphorylation dynamics of RKs and their associated proteins provides mechanistic insight into RK activation and downstream signal transduction. Phos-tag specifically binds phosphomonoester dianions of phosphorylated serine, threonine, and tyrosine residues, which enables Phos-tag-containing SDS-PAGE gels to separate phosphorylated proteins from non-phosphorylated form. Here, we describe a detailed method of Mn2+-Phos-tag SDS-PAGE analysis to detect the ligand-induced in vivo phosphorylation of RKs and associated proteins.
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Affiliation(s)
- Zunyong Liu
- Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Shuguo Hou
- Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, China
| | - Ping He
- Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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Abstract
The light sensor of vertebrate scotopic (low-light) vision, rhodopsin, is a G-protein-coupled receptor comprising a polypeptide chain with bound chromophore, 11-cis-retinal, that exhibits remarkable physicochemical properties. This photopigment is extremely stable in the dark, yet its chromophore isomerises upon photon absorption with 70% efficiency, enabling the activation of its G-protein, transducin, with high efficiency. Rhodopsin's photochemical and biochemical activities occur over very different time-scales: the energy of retinaldehyde's excited state is stored in <1 ps in retinal-protein interactions, but it takes milliseconds for the catalytically active state to form, and many tens of minutes for the resting state to be restored. In this review, we describe the properties of rhodopsin and its role in rod phototransduction. We first introduce rhodopsin's gross structural features, its evolution, and the basic mechanisms of its activation. We then discuss light absorption and spectral sensitivity, photoreceptor electrical responses that result from the activity of individual rhodopsin molecules, and recovery of rhodopsin and the visual system from intense bleaching exposures. We then provide a detailed examination of rhodopsin's molecular structure and function, first in its dark state, and then in the active Meta states that govern its interactions with transducin, rhodopsin kinase and arrestin. While it is clear that rhodopsin's molecular properties are exquisitely honed for phototransduction, from starlight to dawn/dusk intensity levels, our understanding of how its molecular interactions determine the properties of scotopic vision remains incomplete. We describe potential future directions of research, and outline several major problems that remain to be solved.
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Affiliation(s)
- Klaus Peter Hofmann
- Institut für Medizinische Physik und Biophysik (CC2), Charité, and, Zentrum für Biophysik und Bioinformatik, Humboldt-Unversität zu Berlin, Berlin, 10117, Germany.
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia.
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Zhang X, Yin J, Pan W, Li Y, Li N, Tang B. Imaging strategies for receptor tyrosine kinase dimers in living cells. Anal Bioanal Chem 2023; 415:67-82. [PMID: 36190534 DOI: 10.1007/s00216-022-04334-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/04/2022] [Accepted: 09/07/2022] [Indexed: 01/10/2023]
Abstract
Receptor tyrosine kinases (RTKs) are the essential regulators of cell signal transduction pathways and play important roles in biological processes. RTK dimerization is generally considered the first step in receptor activation and cell communication. And the abnormal expression of RTK dimers is closely related to the occurrence and development of many diseases. Therefore, the visualization of RTK dimerization is of great significance for monitoring physiological processes. The genetic and nongenetic imaging strategies have attracted widespread attention due to their high efficiency and high sensitivity. In this review, the RTKs and their dimers as well as the advances in strategies for imaging RTK dimers are introduced. Furthermore, we analyze the limitations of existing imaging strategies and put forward suggestions for the future development of imaging probes. We expect that this review will inspire more in-depth investigation of RTK dimers, which will also broaden the application of strategies of RTK dimers in biomedical areas.
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Abstract
The health problems associated with the aging process are becoming increasingly widespread due to the increase in mean life expectancy taking place globally. While decline of many organ functions is an unavoidable concomitant of senescence, these can be delayed or moderated by a range of factors. Among these are dietary changes and weight control, taking sufficient exercise, and the utilization of various micronutrients. The utility of incurring appropriate changes in lifestyle is generally not confined to a single organ system but has a broadly positive systemic effect.Among one of the most potent means of slowing down age-related changes is the use of melatonin, a widely distributed biological indole. While melatonin is well known as a treatment for insomnia, it has a wide range of beneficial qualities many of which are relevant. This overview describes how several of the properties of melatonin are especially relevant to many of the changes associated with senescence. Changes in functioning of the immune system are particularly marked in the aged, combining diminishing effectiveness with increasing ineffective and harmful activity. Melatonin treatment appears able to moderate and partially reverse this detrimental drift toward immune incompetence.
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Affiliation(s)
- Stephen C Bondy
- Center for Occupational and Environmental Health, University of California, Irvine, CA, USA.
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6
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Dragan P, Atzei A, Sanmukh SG, Latek D. Computational and experimental approaches to probe GPCR activation and signaling. Prog Mol Biol Transl Sci 2022; 193:1-36. [PMID: 36357073 DOI: 10.1016/bs.pmbts.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
G protein-coupled receptors (GPCRs) regulate different physiological functions, e.g., sensation, growth, digestion, reproductivity, nervous and immune systems response, and many others. In eukaryotes, they are also responsible for intercellular communication in response to pathogens. The major primary messengers binding to these cell-surface receptors constitute small-molecule or peptide hormones and neurotransmitters, nucleotides, lipids as well as small proteins. The simplicity of the way how GPCR signaling can be regulated by their endogenous agonists prompted the usage of GPCRs as major drug targets in modern pharmacology. Drugs targeting GPCRs inhibit pathological processes at the very beginning. This enables to significantly reduce the occurrence of morphological changes caused by diseases. Until recently, X-ray crystallography was the method of the first choice to obtain high-resolution structural information about GPCRs. Following X-ray crystallography, cryo-EM gained attention in GPCR studies as a quick and low-cost alternative. FRET microscopy is also widely used for GPCRs in the analysis of protein-protein interactions (PPIs) in intact cells as well as for screening purposes. Regarding computational methods, molecular dynamics (MD) for many years has proven its usefulness in studying the GPCR activation. MODELLER and Rosetta were widely used to generate preliminary homology models of GPCRs for MD simulation systems. Apart from the conventional all-atom approach with explicitly defined solvent, also other techniques have been applied to GPCRs, e.g., MARTINI or hybrid methods involving the coarse-grained representation, less demanding regarding computational resources, and thus offering much larger simulation timescales.
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Affiliation(s)
- Paulina Dragan
- Faculty of Chemistry, University of Warsaw, Warsaw, Poland
| | | | | | - Dorota Latek
- Faculty of Chemistry, University of Warsaw, Warsaw, Poland.
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7
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Kan WL, Cheung Tung Shing KS, Nero TL, Hercus TR, Tvorogov D, Parker MW, Lopez AF. Messing with βc: A unique receptor with many goals. Semin Immunol 2021; 54:101513. [PMID: 34836771 DOI: 10.1016/j.smim.2021.101513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/23/2021] [Indexed: 11/16/2022]
Abstract
Our understanding of the biological role of the βc family of cytokines has evolved enormously since their initial identification as bone marrow colony stimulating factors in the 1960's. It has become abundantly clear over the intervening decades that this family of cytokines has truly astonishing pleiotropic capacity, capable of regulating not only hematopoiesis but also many other normal and pathological processes such as development, inflammation, allergy and cancer. As noted in the current pandemic, βc cytokines contribute to the cytokine storm seen in acutely ill COVID-19 patients. Ongoing studies to discover how these cytokines activate their receptor are revealing insights into the fundamental mechanisms that give rise to cytokine pleiotropy and are providing tantalizing glimpses of how discrete signaling pathways may be dissected for activation with novel ligands for therapeutic benefit.
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Affiliation(s)
- Winnie L Kan
- The Centre for Cancer Biology, SA Pathology and the University of South Australia, Adelaide, South Australia 5000, Australia.
| | - Karen S Cheung Tung Shing
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Tracy L Nero
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Timothy R Hercus
- The Centre for Cancer Biology, SA Pathology and the University of South Australia, Adelaide, South Australia 5000, Australia.
| | - Denis Tvorogov
- The Centre for Cancer Biology, SA Pathology and the University of South Australia, Adelaide, South Australia 5000, Australia.
| | - Michael W Parker
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia; Australian Cancer Research Foundation Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia.
| | - Angel F Lopez
- The Centre for Cancer Biology, SA Pathology and the University of South Australia, Adelaide, South Australia 5000, Australia; Department of Medicine, University of Adelaide, Adelaide, South Australia 5000, Australia; Australian Cancer Research Foundation Cancer Genomics Facility, SA Pathology, Adelaide, South Australia 5000, Australia.
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8
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Herholt A, Sahoo VK, Popovic L, Wehr MC, Rossner MJ. Dissecting intercellular and intracellular signaling networks with barcoded genetic tools. Curr Opin Chem Biol 2021; 66:102091. [PMID: 34644670 DOI: 10.1016/j.cbpa.2021.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/25/2021] [Accepted: 09/03/2021] [Indexed: 11/19/2022]
Abstract
The power of next-generation sequencing has stimulated the development of many analysis techniques for transcriptomics and genomics. More recently, the concept of 'molecular barcoding' has broadened the spectrum of sequencing-based applications to dissect different aspects of intracellular and intercellular signaling. In these assay formats, barcode reporters replace standard reporter genes. The virtually infinitive number of expressed barcode sequences allows high levels of multiplexing, hence accelerating experimental progress. Furthermore, reporter barcodes are used to quantitatively monitor a variety of biological events in living cells which has already provided much insight into complex cellular signaling and will further increase our knowledge in the future.
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Affiliation(s)
- Alexander Herholt
- Department of Psychiatry and Psychotherapy, University Hospital, LMU Munich, Nussbaumstr. 7, 80336 Munich, Germany; Systasy Bioscience GmbH, Balanstr. 6, 81669 Munich, Germany
| | - Vivek K Sahoo
- Systasy Bioscience GmbH, Balanstr. 6, 81669 Munich, Germany
| | - Luksa Popovic
- Department of Psychiatry and Psychotherapy, University Hospital, LMU Munich, Nussbaumstr. 7, 80336 Munich, Germany; Systasy Bioscience GmbH, Balanstr. 6, 81669 Munich, Germany
| | - Michael C Wehr
- Department of Psychiatry and Psychotherapy, University Hospital, LMU Munich, Nussbaumstr. 7, 80336 Munich, Germany; Systasy Bioscience GmbH, Balanstr. 6, 81669 Munich, Germany
| | - Moritz J Rossner
- Department of Psychiatry and Psychotherapy, University Hospital, LMU Munich, Nussbaumstr. 7, 80336 Munich, Germany.
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9
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Wang W, Bian J, Sun Y, Li Z. The new fate of internalized membrane receptors: Internalized activation. Pharmacol Ther 2021; 233:108018. [PMID: 34626676 DOI: 10.1016/j.pharmthera.2021.108018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 12/23/2022]
Abstract
Classically, the fate of internalized membrane receptors includes receptor degradation and receptor recycling. However, recent findings have begun to challenge these views. Much research demonstrated that many internalized membrane receptors can trigger distinct signal activation rather than being desensitized inside the cell. Here, we introduce the concept of "internalized activation" which not only represents a new mode of receptor activation, but also endows the new fate for receptor internalization (from death to life). The new activation mode and fate of membrane receptor are ubiquitous and have unique theoretical significance. We systematically put forward the features, process, and regulation of "internalized activation" and its significance in signal transduction and diseases. "Internalized activation" will provide a completely new understanding for the theory of receptor activation, internalization and novel drug targets for precision medicine.
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Affiliation(s)
- Wenjing Wang
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
| | - Jingwei Bian
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
| | - Yang Sun
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
| | - Zijian Li
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China; Department of Pharmacy, Peking University Third Hospital, Beijing 100191, China.
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10
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Jiang LH, Caseley EA, Muench SP, Roger S. Structural basis for the functional properties of the P2X7 receptor for extracellular ATP. Purinergic Signal 2021; 17:331-344. [PMID: 33987781 PMCID: PMC8410900 DOI: 10.1007/s11302-021-09790-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/19/2021] [Indexed: 02/06/2023] Open
Abstract
The P2X7 receptor, originally known as the P2Z receptor due to its distinctive functional properties, has a structure characteristic of the ATP-gated ion channel P2X receptor family. The P2X7 receptor is an important mediator of ATP-induced purinergic signalling and is involved the pathogenesis of numerous conditions as well as in the regulation of diverse physiological functions. Functional characterisations, in conjunction with site-directed mutagenesis, molecular modelling, and, recently, structural determination, have provided significant insights into the structure–function relationships of the P2X7 receptor. This review discusses the current understanding of the structural basis for the functional properties of the P2X7 receptor.
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Affiliation(s)
- Lin-Hua Jiang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
| | - Emily A Caseley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- Faculty of Medicine and Health, Leeds Institute of Rheumatic and Musculoskeletal Medicine, St James's University Hospital, Leeds, UK
| | - Steve P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Sébastien Roger
- EA4245, Transplantation, Immunology and Inflammation, Faculty of Medicine, University of Tours, Tours, France
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11
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Shen XM, Di L, Shen S, Zhao Y, Neumeyer AM, Selcen D, Sine SM, Engel AG. A novel fast-channel myasthenia caused by mutation in β subunit of AChR reveals subunit-specific contribution of the intracellular M1-M2 linker to channel gating. Exp Neurol 2020; 331:113375. [PMID: 32504635 DOI: 10.1016/j.expneurol.2020.113375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/27/2020] [Accepted: 06/01/2020] [Indexed: 10/24/2022]
Abstract
Genetic variants causing the fast-channel congenital myasthenic syndrome (CMS) have been identified in the α, δ, and ε but not the β subunit of acetylcholine receptor (AChR). A 16-year-old girl with severe myasthenia had low-amplitude and fast-decaying miniature endplate potentials. Mutation analysis revealed two heteroallelic variants in CHRNB1 encoding the AChR β subunit: a novel c.812C>T (p.P248L) variant in M1-M2 linker (p.P271L in HGVS nomenclature), and a ~430 bp deletion causing loss of exon 8 leading to frame-shift and a premature stop codon (p.G251Dfs*21). P248 is conserved in all β subunits of different species, but not in other AChR subunits. Measurements of radio-labeled α-bungarotoxin binding show that βP248L reduces AChR expression to 60% of wild-type. Patch clamp recordings of ACh-elicited single channel currents demonstrate that βP248L shortens channel opening bursts from 3.3 ms to 1.2 ms, and kinetic analyses predict that the decay of the synaptic response is accelerated 2.4-fold due to reduced probability of channel reopening. Substituting βP248 with threonine, alanine or glycine reduces the burst duration to 2.3, 1.7, and 1.5 ms, respectively. In non-β subunits, substituting leucine for residues corresponding to βP248 prolongs the burst duration to 4.5 ms in the α subunit, shortens it to 2.2 ms in the δ subunit, and has no effect in the ε subunit. Conversely, substituting proline for residues corresponding to βP248 prolongs the burst duration to 8.7 ms in the α subunit, to 4.6 ms in the δ subunit, but has no effect in the ε subunit. Thus, this fast channel CMS is caused by the dual defects of βP248L in reducing expression of the mutant receptor and accelerating the decay of the synaptic response. The results also reveal subunit-specific contributions of the M1-M2 linker to the durations of channel opening bursts.
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Affiliation(s)
- Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA.
| | - Li Di
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Shelley Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Yuying Zhao
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Ann M Neumeyer
- Department of Child Neurology, Massachusetts General Hospital for Children, Lexington, MA, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering and Receptor Biology Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA; Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Andrew G Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA.
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Sniecikowska J, Newman-Tancredi A, Kolaczkowski M. From Receptor Selectivity to Functional Selectivity: The Rise of Biased Agonism in 5-HT1A Receptor Drug Discovery. Curr Top Med Chem 2019; 19:2393-2420. [PMID: 31544717 DOI: 10.2174/1568026619666190911122040] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 02/08/2023]
Abstract
Despite extensive efforts to design serotonin 5-HT1A receptor compounds, there are currently no clinically available selective agonists to explore the therapeutic potential of activating this receptor. Commonly used drugs targeting 5-HT1A receptors, such as buspirone or other azapirone compounds, possess only limited selectivity over cross-reacting sites, act as partial agonists for 5-HT1A receptor activation, and are metabolically labile, generating active metabolites. In addition, drug discovery has been hampered by the multiplicity of 5-HT1A receptor subpopulations, expressed in different brain regions, that are coupled to distinct molecular signaling mechanisms and mediate a wide variety of physiological responses, both desired and undesired. In this context, advances in 5-HT1A receptor drug discovery have attracted attention of novel 'biased agonists' that are selective, efficacious and preferentially target the brain regions that mediate therapeutic activity without triggering side effects. The prototypical first-in-class compound NLX-101 (a.k.a. F15599; 3-chloro-4-fluorophenyl-[4-fluoro-4-[[(5-methylpyrimidin-2-ylmethyl)amino]methyl]piperidin- 1-yl]methanone), preferentially activates 5-HT1A receptors in cortical regions and exhibits potent, rapidacting and sustained antidepressant-like and procognitive properties in animal models. Here the background has been reviewed that led to the discovery of the class of 1-(1-benzoylpiperidin-4- yl)methanamine derivatives, including NLX-101, as well as recent advances in discovery of novel 5-HT1A receptor biased agonists, notably aryloxyethyl derivatives of 1‑(1-benzoylpiperidin-4yl)methanamine which show promising pharmacological activity both in vitro and in vivo. Overall, the results suggest that opportunities exist for innovative drug discovery of selective 5-HT1A receptor biased agonists that may open new avenues for the treatment of CNS disorders involving dysfunction of serotonergic neurotransmission.
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Affiliation(s)
- Joanna Sniecikowska
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Chair of Pharmaceutical Chemistry, 9 Medyczna Street, 30-688 Krakow, Poland
| | | | - Marcin Kolaczkowski
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Chair of Pharmaceutical Chemistry, 9 Medyczna Street, 30-688 Krakow, Poland
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Hao J, Chen Q. Insights into the Structural Aspects of the mGlu Receptor Orthosteric Binding Site. Curr Top Med Chem 2019; 19:2421-2446. [PMID: 31660833 DOI: 10.2174/1568026619666191011094935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/28/2019] [Accepted: 09/04/2019] [Indexed: 02/06/2023]
Abstract
The amino terminal domain (ATD) of the metabotropic glutamate (mGlu) receptors contains the orthosteric glutamate recognition site, which is highly conserved across the eight mGlu receptor subtypes. In total, 29 X-ray crystal structures of the mGlu ATD proteins have been reported to date. These structures span across 3 subgroups and 6 subtypes, and include apo, agonist- and antagonist-bound structures. We will discuss the insights gained from the analysis of these structures with the focus on the interactions contributing to the observed group and subtype selectivity for select agonists. Furthermore, we will define the full expanded orthosteric ligand binding pocket (LBP) of the mGlu receptors, and discuss the macroscopic features of the mGlu ATD proteins.
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Affiliation(s)
- Junliang Hao
- Discovery Chemistry Research and Technologies, Lilly Research Laboratory, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, United States
| | - Qi Chen
- Discovery Chemistry Research and Technologies, Lilly Research Laboratory, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, United States
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Shalaeva DN, Cherepanov DA, Galperin MY, Vriend G, Mulkidjanian AY. G protein-coupled receptors of class A harness the energy of membrane potential to increase their sensitivity and selectivity. Biochim Biophys Acta Biomembr 2019; 1861:183051. [PMID: 31449800 DOI: 10.1016/j.bbamem.2019.183051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/28/2019] [Accepted: 08/21/2019] [Indexed: 12/31/2022]
Abstract
The human genome contains about 700 genes of G protein-coupled receptors (GPCRs) of class A; these seven-helical membrane proteins are the targets of almost half of all known drugs. In the middle of the helix bundle, crystal structures reveal a highly conserved sodium-binding site, which is connected with the extracellular side by a water-filled tunnel. This binding site contains a sodium ion in those GPCRs that are crystallized in their inactive conformations but does not in those GPCRs that are trapped in agonist-bound active conformations. The escape route of the sodium ion upon the inactive-to-active transition and its very direction have until now remained obscure. Here, by modeling the available experimental data, we show that the sodium gradient over the cell membrane increases the sensitivity of GPCRs if their activation is thermodynamically coupled to the sodium ion translocation into the cytoplasm but decreases it if the sodium ion retreats into the extracellular space upon receptor activation. The model quantitatively describes the available data on both activation and suppression of distinct GPCRs by membrane voltage. The model also predicts selective amplification of the signal from (endogenous) agonists if only they, but not their (partial) analogs, induce sodium translocation. Comparative structure and sequence analyses of sodium-binding GPCRs indicate a key role for the conserved leucine residue in the second transmembrane helix (Leu2.46) in coupling sodium translocation to receptor activation. Hence, class A GPCRs appear to harness the energy of the transmembrane sodium potential to increase their sensitivity and selectivity.
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Affiliation(s)
- Daria N Shalaeva
- School of Physics, Osnabrueck University, 49069 Osnabrück, Germany; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Dmitry A Cherepanov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia; N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Russia.
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| | - Gert Vriend
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, 6525 HP Nijmegen, the Netherlands.
| | - Armen Y Mulkidjanian
- School of Physics, Osnabrueck University, 49069 Osnabrück, Germany; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia; School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia.
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15
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Randáková A, Dolejší E, Rudajev V, Zimčík P, Doležal V, El-Fakahany EE, Jakubík J. Role of membrane cholesterol in differential sensitivity of muscarinic receptor subtypes to persistently bound xanomeline. Neuropharmacology 2018; 133:129-144. [PMID: 29407765 DOI: 10.1016/j.neuropharm.2018.01.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 01/03/2018] [Accepted: 01/21/2018] [Indexed: 01/24/2023]
Abstract
Xanomeline (3-(Hexyloxy)-4-(1-methyl-1,2,5,6-tetrahydropyridin-3-yl)-1,2,5-thiadiazole) is a muscarinic agonist that is considered to be functionally selective for the M1/M4 receptor subtypes. Part of xanomeline binding is resistant to washing. Wash-resistant xanomeline activates muscarinic receptors persistently, except for the M5 subtype. Mutation of leucine 6.46 to isoleucine at M1 or M4 receptors abolished persistent activation by wash-resistant xanomeline. Reciprocal mutation of isoleucine 6.46 to leucine at the M5 receptor made it sensitive to activation by wash-resistant xanomeline. Lowering of membrane cholesterol made M1 and M4 mutants and M5 wild type receptors sensitive to activation by wash-resistant xanomeline. Molecular docking revealed a cholesterol binding site in the groove between transmembrane helices 6 and 7. Molecular dynamics showed that interaction of cholesterol with this binding site attenuates receptor activation. We hypothesize that differences in cholesterol binding to this site between muscarinic receptor subtypes may constitute the basis for xanomeline apparent functional selectivity and may have notable therapeutic implications. Differences in receptor-membrane interactions, rather than in agonist-receptor interactions, represent a novel possibility to achieve pharmacological selectivity. Our findings may be applicable to other G protein coupled receptors.
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Affiliation(s)
- Alena Randáková
- Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Eva Dolejší
- Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Vladimír Rudajev
- Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Pavel Zimčík
- Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Vladimír Doležal
- Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Esam E El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN 55455, USA
| | - Jan Jakubík
- Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic.
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16
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Liu Y, Chen LY, Zeng H, Ward R, Wu N, Ma L, Mu X, Li QL, Yang Y, An S, Guo XX, Hao Q, Xu TR. Assessing the real-time activation of the cannabinoid CB1 receptor and the associated structural changes using a FRET biosensor. Int J Biochem Cell Biol 2018; 99:114-124. [PMID: 29626639 DOI: 10.1016/j.biocel.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/25/2018] [Accepted: 04/04/2018] [Indexed: 11/18/2022]
Abstract
The cannabinoid receptor 1 (CB1) is mainly expressed in the nervous system and regulates learning, memory processes, pain and energy metabolism. However, there is no way to directly measure its activation. In this study, we constructed a CB1 intramolecular fluorescence resonance energy transfer (FRET) sensor, which could measure CB1 activation by monitoring structural changes between the third intracellular loop and the C-terminal tail. CB1 agonists induced a time- and concentration-dependent increase in the FRET signal, corresponding to a reduction in the distance between the third intracellular loop and the C-terminal tail. This, in turn, mobilized intracellular Ca2+, inhibited cAMP accumulation, and increased phosphorylation of the ERK1/2 MAP kinases. The activation kinetics detected using this method were consistent with those from previous reports. Moreover, the increased FRET signal was markedly inhibited by the CB1 antagonist rimonabant, which also reduced phosphorylation of the ERK1/2 MAP kinases. We mutated a single cysteine residue in the sensor (at position 257 or 264) to alanine. Both mutation reduced the agonist-induced increase in FRET signal and structural changes in the CB1 receptor, which attenuated phosphorylation of the ERK1/2 MAP kinases. In summary, our sensor directly assesses the kinetics of CB1 activation in real-time and can be used to monitor CB1 structure and function.
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Affiliation(s)
- Ying Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Lu-Yao Chen
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Hong Zeng
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Richard Ward
- Center for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Nan Wu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Li Ma
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Xi Mu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Qiu-Lan Li
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Yang Yang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Xiao-Xi Guo
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Qian Hao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Tian-Rui Xu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
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Karageorgos V, Venihaki M, Sakellaris S, Pardalos M, Kontakis G, Matsoukas MT, Gravanis A, Margioris A, Liapakis G. Current understanding of the structure and function of family B GPCRs to design novel drugs. Hormones (Athens) 2018; 17:45-59. [PMID: 29858864 DOI: 10.1007/s42000-018-0009-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/25/2018] [Indexed: 01/10/2023]
Abstract
Family B of G-protein-coupled receptors (GPCRs) and their ligands play a central role in a number of homeostatic mechanisms in the endocrine, gastrointestinal, skeletal, immune, cardiovascular and central nervous systems. Alterations in family B GPCR-regulated homeostatic mechanisms may cause a variety of potentially life-threatening conditions, signifying the necessity to develop novel ligands targeting these receptors. Obtaining structural and functional information on family B GPCRs will accelerate the development of novel drugs to target these receptors. Family B GPCRs are proteins that span the plasma membrane seven times, thus forming seven transmembrane domains (TM1-TM7) which are connected to each other by three extracellular (EL) and three intracellular (IL) loops. In addition, these receptors have a long extracellular N-domain and an intracellular C-tail. The upper parts of the TMs and ELs form the J-domain of receptors. The C-terminal region of peptides first binds to the N-domain of receptors. This 'first-step' interaction orients the N-terminal region of peptides towards the J-domain of receptors, thus resulting in a 'second-step' of ligand-receptor interaction that activates the receptor. Activation-associated structural changes of receptors are transmitted through TMs to their intracellular regions and are responsible for their interaction with the G proteins and activation of the latter, thus resulting in a biological effect. This review summarizes the current information regarding the structure and function of family B GPCRs and their physiological and pathophysiological roles.
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Affiliation(s)
- Vlasios Karageorgos
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - Maria Venihaki
- Department of Clinical Chemistry, School of Medicine, University of Crete, Heraklion, Crete, Greece
| | - Stelios Sakellaris
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - Michail Pardalos
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - George Kontakis
- Department of Orthopedics, University Hospital of Heraklion, Crete, Greece
| | | | - Achille Gravanis
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - Andreas Margioris
- Department of Clinical Chemistry, School of Medicine, University of Crete, Heraklion, Crete, Greece
| | - George Liapakis
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece.
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18
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Abstract
Also expressed in various peripheral tissues, the type-1 cannabinoid receptor (CB1R) is the predominant G protein-coupled receptor (GPCR) in brain, where it is responsible for retrograde control of neurotransmitter release. Cellular signaling mediated by CB1R is involved in numerous physiological processes, and pharmacological CB1R modulation is considered a tenable therapeutic approach for diseases ranging from substance-use disorders and glaucoma to metabolic syndrome. Despite the design and synthesis of a variety of bioactive small molecules targeted to the CB1R orthosteric ligand-binding site, the potential of CB1R as a therapeutic GPCR has been largely unrealized due to adverse events associated with typical orthosteric CB1R agonists and antagonists/inverse agonists. Modulation of CB1R-mediated signal transmission by targeting alternative allosteric ligand-binding site(s) on the receptor has garnered interest as a potentially safer and more effective therapeutic modality. This chapter highlights the design and synthesis of novel, pharmacologically active CB1R allosteric modulators and emphasizes how their molecular properties and the positive and negative allosteric control they exert can lead to improved CB1R-targeted pharmacotherapeutics, as well as designer covalent probes that can be used to map CB1R allosteric binding domains and inform structure-based drug design.
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Affiliation(s)
- Abhijit R Kulkarni
- School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, United States
| | - Sumanta Garai
- School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, United States
| | - David R Janero
- School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, United States; Center for Drug Discovery, Northeastern University, Boston, MA, United States; College of Science, Northeastern University, Boston, MA, United States; Health Sciences Entrepreneurs, Northeastern University, Boston, MA, United States
| | - Ganesh A Thakur
- School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, United States.
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19
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Woolley MJ, Conner AC. Understanding the common themes and diverse roles of the second extracellular loop (ECL2) of the GPCR super-family. Mol Cell Endocrinol 2017; 449:3-11. [PMID: 27899324 DOI: 10.1016/j.mce.2016.11.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/02/2016] [Accepted: 11/24/2016] [Indexed: 11/16/2022]
Abstract
The extracellular loops (ECLs) of G protein-coupled receptors (GPCRs) can bind directly to docked orthosteric or allosteric ligands, they can contain transient contact points for ligand entry into the transmembrane (TM) bundle and they can regulate the activation of the receptor signalling pathways. Of the three ECLs, ECL2 is the largest and most structurally diverse reflecting its functional importance. This has been shown through biochemical techniques and has been supported by the many subsequent crystal structures of GPCRs bound to both agonists and antagonists. ECL2 shares common structural features between (and sometimes across) receptor sub-families and can facilitate ligand entry to the TM core or act directly as a surface of the ligand-binding pocket. Structural similarities seem to underpin common binding mechanisms; however, where these exist, variations in primary sequence ensure ligand-binding specificity. This review will compare current understanding of the structural themes and main functional roles of ECL2 in ligand binding, activation and regulation of the major families of GPCRs.
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Affiliation(s)
- Michael J Woolley
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Alex C Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
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20
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Ehlert FJ, Stein RSL. Estimation of the receptor-state affinity constants of ligands in functional studies using wild type and constitutively active mutant receptors: Implications for estimation of agonist bias. J Pharmacol Toxicol Methods 2016; 83:94-106. [PMID: 27725245 DOI: 10.1016/j.vascn.2016.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 09/17/2016] [Accepted: 09/27/2016] [Indexed: 10/20/2022]
Abstract
We describe a method for estimating the affinities of ligands for active and inactive states of a G protein-coupled receptor (GPCR). Our protocol involves measuring agonist-induced signaling responses of a wild type GPCR and a constitutively active mutant of it under control conditions and after partial receptor inactivation or reduced receptor expression. Our subsequent analysis is based on the assumption that the activating mutation increases receptor isomerization into the active state without affecting the affinities of ligands for receptor states. A means of confirming this assumption is provided. Global nonlinear regression analysis yields estimates of 1) the active (Kact) and inactive (Kinact) receptor-state affinity constants, 2) the isomerization constant of the unoccupied receptor (Kq-obs), and 3) the sensitivity constant of the signaling pathway (KE-obs). The latter two parameters define the output response of the receptor, and hence, their ratio (Kq-obs/KE) is a useful measure of system bias. If the cellular system is reasonably stable and the Kq-obs and KE-obs values of the signaling pathway are known, the Kact and Kinact values of additional agonists can be estimated in subsequent experiments on cells expressing the wild type receptor. We validated our method through computer simulation, an analytical proof, and analysis of previously published data. Our approach provides 1) a more meaningful analysis of structure-activity relationships, 2) a means of validating in silico docking experiments on active and inactive receptor structures and 3) an absolute, in contrast to relative, measure of agonist bias.
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Affiliation(s)
- Frederick J Ehlert
- Department of Pharmacology, School of Medicine, University of California, Irvine, Irvine, CA 92697-4625, United States; Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA 92697-4625, United States.
| | - Richard S L Stein
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA 92697-4625, United States
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21
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Liu Y, Zhang L, Shao XX, Hu MJ, Liu YL, Xu ZG, Guo ZY. A negatively charged transmembrane aspartate residue controls activation of the relaxin-3 receptor RXFP3. Arch Biochem Biophys 2016; 604:113-20. [PMID: 27353281 DOI: 10.1016/j.abb.2016.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 06/16/2016] [Accepted: 06/21/2016] [Indexed: 01/18/2023]
Abstract
Relaxin-3 is an insulin/relaxin superfamily neuropeptide involved in the regulation of food intake and stress response via activation of its cognate receptor RXFP3, an A-class G protein-coupled receptor (GPCR). In recent studies, a highly conserved ExxxD motif essential for binding of relaxin-3 has been identified at extracellular end of the second transmembrane domain (TMD2) of RXFP3. For most of the A-class GPCRs, a highly conserved negatively charged Asp residue (Asp(2.50) using Ballesteros-Weinstein numbering and Asp128 in human RXFP3) is present at the middle of TMD2. To elucidate function of the conserved transmembrane Asp128, in the present work we replaced it with other residues and the resultant RXFP3 mutants all retained quite high ligand-binding potency, but their activation and agonist-induced internalization were abolished or drastically decreased. Thus, the negatively charged transmembrane Asp128 controlled transduction of agonist-binding information from the extracellular region to the intracellular region through maintaining RXFP3 in a metastable state for efficient conformational change induced by binding of an agonist.
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22
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Abstract
Adrenergic signaling, in particular signaling in the sympathetic nervous system, is a prime example of the control of an essential physiological system. It has served as a model system both for the control of mediator release and for receptor signaling and regulation. This review covers the historical development of the field and then addresses issues that represent key fields of ongoing research: the mechanisms and kinetics of receptor activation, temporal patterns of downstream signaling and signal bias, receptor mobility and aggregation, and signal compartmentation and specificity. The available evidence suggests that adrenergic signaling may involve complex spatiotemporal patterns, which give texture to the signaling process and may contain additional biological information.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
- Rudolf Virchow Center, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
- Comprehensive Heart Failure Center, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
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23
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Abstract
The discoidin domain receptors, DDR1 and DDR2, are nonintegrin collagen receptors that are members of the receptor tyrosine kinase family. Both DDRs bind a number of different collagen types and play important roles in embryo development. Dysregulated DDR function is associated with progression of various human diseases, including fibrosis, arthritis, and cancer. By interacting with key components of the extracellular matrix and displaying distinct activation kinetics, the DDRs form a unique subfamily of receptor tyrosine kinases. DDR-facilitated cellular functions include cell migration, cell survival, proliferation, and differentiation, as well as remodeling of extracellular matrices. This review summarizes the current knowledge of DDR-ligand interactions, DDR-initiated signal pathways and the molecular mechanisms that regulate receptor function. Also discussed are the roles of DDRs in development and disease progression.
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Affiliation(s)
- Birgit Leitinger
- National Heart and Lung Institute, Imperial College London, London, United Kingdom.
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24
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Balasuriya D, Takahashi H, Srivats S, Edwardson JM. Activation-induced structural change in the GluN1/GluN3A excitatory glycine receptor. Biochem Biophys Res Commun 2014; 450:1452-7. [PMID: 25017909 DOI: 10.1016/j.bbrc.2014.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 07/02/2014] [Indexed: 11/26/2022]
Abstract
Unlike GluN2-containing N-methyl-d-aspartate (NMDA) receptors, which require both glycine and glutamate for activation, receptors composed of GluN1 and GluN3 subunits are activated by glycine alone. Here, we used atomic force microscopy (AFM) imaging to examine the response to activation of the GluN1/GluN3A excitatory glycine receptor. GluN1 and GluN3A subunits were shown to interact intimately within transfected tsA 201 cells. Isolated GluN1/GluN3A receptors integrated into lipid bilayers responded to addition of either glycine or d-serine, but not glutamate, with a ∼1 nm reduction in height of the extracellular domain. The height reduction in response to glycine was abolished by the glycine antagonist 5,7-dichlorokynurenic acid. Our results represent the first demonstration of the effect of activation on the conformation of this receptor.
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Affiliation(s)
- Dilshan Balasuriya
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Hirohide Takahashi
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Shyam Srivats
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - J Michael Edwardson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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25
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Campbell AP, MacDougall IJA, Griffith R, Finch AM. An aspartate in the second extracellular loop of the α(1B) adrenoceptor regulates agonist binding. Eur J Pharmacol 2014; 733:90-6. [PMID: 24690260 DOI: 10.1016/j.ejphar.2014.03.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/20/2014] [Accepted: 03/24/2014] [Indexed: 11/30/2022]
Abstract
The extracellular loops of the adrenoceptors present a potential therapeutic target in the design of highly selective adrenergic drugs. These regions are less conserved than the orthosteric binding site but have to date not been implicated in activation of adrenoceptors. A previously generated homology model identified an extracellular residue, D191, as a potential regulator of agonist binding. We have generated mutants of the α1B adrenoceptor replacing the charged aspartate, D191, as well as a potential interaction partner, K331, with uncharged alanines to observe effects on ligand binding and receptor activation. Significant 4-6 fold reductions in affinity for the endogenous agonists, epinephrine and norepinephrine were observed for receptors with the D191A mutation in the second extracellular loop. While changes in EC50 were observed, operational analysis yielded no apparent change in receptor activation. Based on these findings, we suggest that D191, in the second extracellular loop of the α1B adrenoceptor, acts as a 'point of first contact' for the receptor's endogenous agonists. Implication of the non-conserved extracellular regions of the receptor in agonist binding makes it a potential target for the design of highly selective drugs.
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Affiliation(s)
- Adrian P Campbell
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Iain J A MacDougall
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Renate Griffith
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Angela M Finch
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Kensington, NSW 2052, Australia.
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26
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Abstract
Constitutively active mutants (CAMs) of gonadotropin receptors are, in general, rare conditions. Luteinizing hormone-choriogonadotropin receptor (LHCGR) CAMs provoke the dramatic phenotype of familial gonadotropin-independent isosexual male-limited precocious puberty, whereas in females, there is not yet any identified phenotype. Only one isolated follicle-stimulating hormone receptor (FSHR) CAM (Asp567Gly) has so far been detected in a single male patient, besides other FSHR weak CAMs linked to pregnancy-associated ovarian hyperstimulation syndrome or to impaired desensitization and internalization. Several animal models have been developed for studying enhanced gonadotropin action; in addition to unraveling valuable new information about the possible phenotypes of isolated FSHR and LHCGR CAMs in women, the information obtained from these mouse models has served multiple translational goals, including the development of new diagnostic and therapeutic targets as well as the prediction of phenotypes for mutations not yet identified in humans. Mutagenesis and computational studies have shed important information on the physiopathogenic mechanisms leading to constitutive activity of gonadotropin receptors; a common feature in these receptor CAMs is the release of stabilizing interhelical interactions between transmembrane domains (TMDs) 3 and 6 leading to an increase, with respect to the wild-type receptor, in the solvent accessibility at the cytosolic extension of TMDs 3, 5, and 6, which involves the highly conserved Glu/Asp-Arg-Tyr/Trp sequence. In this chapter, we summarize the structural features, functional consequences, and mechanisms that lead to constitutive activation of gonadotropin receptor CAMs and provide information on pharmacological approaches that might potentially modulate gonadotropin receptor CAM function.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Research Support Network, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" and Universidad Nacional Autónoma de México, México D.F., Mexico.
| | - Eric Reiter
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; BIOS Group, INRA, UMR85, Unité Physiologie de la Reproduction et des Comportements, Nouzilly, France; CNRS, UMR7247, Nouzilly, France; Université François Rabelais, Tours, France
| | - George Bousfield
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Department of Biological Sciences, Wichita State University, Wichita, Kansas, USA
| | - James A Dias
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, USA
| | - Ilpo Huhtaniemi
- Studium Consortium for Research and Training in Reproductive Sciences (sCORTS), Tours, France; Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
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27
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Abstract
Rhodopsin is the light receptor in rod photoreceptor cells of the retina that initiates scotopic vision. In the dark, rhodopsin is bound to the chromophore 11-cis retinal, which locks the receptor in an inactive state. The maintenance of an inactive rhodopsin in the dark is critical for rod photoreceptor cells to remain highly sensitive. Perturbations by mutation or the absence of 11-cis retinal can cause rhodopsin to become constitutively active, which leads to the desensitization of photoreceptor cells and, in some instances, retinal degeneration. Constitutive activity can arise in rhodopsin by various mechanisms and can cause a variety of inherited retinal diseases including Leber congenital amaurosis, congenital night blindness, and retinitis pigmentosa. In this review, the molecular and structural properties of different constitutively active forms of rhodopsin are overviewed, and the possibility that constitutive activity can arise from different active-state conformations is discussed.
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Affiliation(s)
- Paul Shin-Hyun Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, USA.
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28
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Nieminen T, Toivanen PI, Rintanen N, Heikura T, Jauhiainen S, Airenne KJ, Alitalo K, Marjomäki V, Ylä-Herttuala S. The impact of the receptor binding profiles of the vascular endothelial growth factors on their angiogenic features. Biochim Biophys Acta Gen Subj 2013; 1840:454-63. [PMID: 24112971 DOI: 10.1016/j.bbagen.2013.10.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/12/2013] [Accepted: 10/01/2013] [Indexed: 01/13/2023]
Abstract
BACKGROUND Vascular endothelial growth factors (VEGFs) are potential therapeutic agents for treatment of ischemic diseases. Their angiogenic effects are mainly mediated through VEGF receptor 2 (VEGFR2). METHODS Receptor binding, signaling, and biological efficacy of several VEGFR2 ligands were compared to determine their characteristics regarding angiogenic activity and vascular permeability. RESULTS Tested VEGFR2 ligands induced receptor tyrosine phosphorylation with different efficacy depending on their binding affinities. However, the tyrosine phosphorylation pattern and the activation of the major downstream signaling pathways were comparable. The maximal angiogenic effect stimulated by different VEGFR2 ligands was dependent on their ability to bind to co-receptor Neuropilin (Nrp), which was shown to form complexes with VEGFR2. The ability of these VEGFR2 ligands to induce vascular permeability was dependent on their concentration and VEGFR2 affinity, but not on Nrp binding. CONCLUSIONS VEGFR2 activation alone is sufficient for inducing endothelial cell proliferation, formation of tube-like structures and vascular permeability. The level of VEGFR2 activation is dependent on the binding properties of the ligand used. However, closely similar activation pattern of the receptor kinase domain is seen with all VEGFR2 ligands. Nrp binding strengthens the angiogenic potency without increasing vascular permeability. GENERAL SIGNIFICANCE This study sheds light on how different structurally closely related VEGFR2 ligands bind to and signal via VEGFR2/Nrp complex to induce angiogenesis and vascular permeability. The knowledge of this study could be used for designing VEGFR2/Nrp ligands with improved therapeutic properties.
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Affiliation(s)
- Tiina Nieminen
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, FI-70211 Kuopio, Finland.
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29
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Michaelson SD, Paulsen IM, Kozuska JL, Martin IL, Dunn SMJ. Importance of recognition loops B and D in the activation of human 5-HT₃ receptors by 5-HT and meta-chlorophenylbiguanide. Neuropharmacology 2013; 73:398-403. [PMID: 23810831 DOI: 10.1016/j.neuropharm.2013.06.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/14/2013] [Accepted: 06/12/2013] [Indexed: 10/26/2022]
Abstract
The 5-HT₃ receptor is a cation selective member of the pentameric Cys-loop ligand-gated ion channels. While five subunits are known to exist, only two receptor subtypes have been significantly characterized: the homomeric receptor consisting of five A subunits and the heteromeric receptor containing both A and B subunits. The agonist recognition and activation of these receptors is orchestrated by six recognition loops three, A-C, on the principal subunit, and three, D-F, on the complementary subunit. In this study we have focused on the B loop of the principal subunit and loop D of the complementary subunit where aligned amino acids differ between the two subunits. A mutational analysis has been carried out using both 5-HT and m-chlorophenylbiguanide (mCPBG) to characterize receptor activation in the mutant receptors using two-electrode voltage clamp in Xenopus oocytes. The results show that the B loop W178I mutation of the 5-HT3A subunit markedly reduces the efficacy of mCPBG in both the homomeric and heteromeric receptors, while activation by 5-HT remains intact. Replacement of the D loop amino acid triplet RQY of the 5-HT3A subunit, with the aligned residues from the 5-HT3B subunit, QEV, converts 5-HT to a weak partial agonist in both the homomer and heteromer, but does not compromise activation by mCPBG. Exchange of the RQY triplet for the 5-HT3B subunit homologue, QEV, increases the Hill coefficient and decreases the EC₅₀ of this mutant when expressed with the wild type 5-HT3A subunit.
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Affiliation(s)
- S D Michaelson
- Department of Pharmacology, University of Alberta, 9-70 Medical Sciences Building, Edmonton, AB, Canada T6H 2H7
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30
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Patterson JT, Li P, Day JW, Gelfanov VM, Dimarchi RD. A hydrophobic site on the GLP-1 receptor extracellular domain orients the peptide ligand for signal transduction. Mol Metab 2013; 2:86-91. [PMID: 24199154 DOI: 10.1016/j.molmet.2013.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 12/26/2012] [Accepted: 01/03/2013] [Indexed: 11/24/2022] Open
Abstract
Structure-function studies have analyzed substitutions within the glucagon-like peptide-1 (GLP-1) sequence that increase resistance to proteolysis, however, the investigation into how such substitutions alter interactions at the GLP-1 receptor (GLP-1R) has captured less attention. This work describes our efforts at identifying relevant interactions between peptide ligands and the GLP-1R extracellular domain that contribute to the positioning of the peptide N-terminus for receptor activation. Alanine substitutions at hydrophilic (Glu127⁎ and Glu128⁎) and hydrophobic (Leu32⁎) GLP-1R residues were previously shown to differentially interact with GLP-1 and exendin-4. We examined if these receptor residues influence the activity of GLP-1- and exendin-4-based peptides containing either alanine or glycine at position 2. Additionally, a series of glucagon-based peptides were studied to determine how the central to C-terminal region affects activity. Our results suggest that peptide binding to the GLP-1R is largely driven by hydrophobic interactions with the extracellular domain that orient the N-terminus for activation.
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31
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Chen PH, Chen X, He X. Platelet-derived growth factors and their receptors: structural and functional perspectives. Biochim Biophys Acta 2012; 1834:2176-86. [PMID: 23137658 DOI: 10.1016/j.bbapap.2012.10.015] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/24/2012] [Accepted: 10/26/2012] [Indexed: 12/13/2022]
Abstract
The four types of platelet-derived growth factors (PDGFs) and the two types of PDGF receptors (PDGFRs, which belong to class III receptor tyrosine kinases) have important functions in the development of connective tissue cells. Recent structural studies have revealed novel mechanisms of PDGFs in propeptide loading and receptor recognition/activation. The detailed structural understanding of PDGF-PDGFR signaling has provided a template that can aid therapeutic intervention to counteract the aberrant signaling of this normally silent pathway, especially in proliferative diseases such as cancer. This review summarizes the advances in the PDGF system with a focus on relating the structural and functional understandings, and discusses the basic aspects of PDGFs and PDGFRs, the mechanisms of activation, and the insights into the therapeutic antagonism of PDGFRs. This article is part of a Special Issue entitled: Emerging recognition and activation mechanisms of receptor tyrosine kinases.
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Affiliation(s)
- Po-Han Chen
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Searle 8-417, 303 East Chicago Avenue, Chicago, IL 60611, USA
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32
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Wang X. Structural studies of GDNF family ligands with their receptors-Insights into ligand recognition and activation of receptor tyrosine kinase RET. Biochim Biophys Acta 2012; 1834:2205-12. [PMID: 23085183 DOI: 10.1016/j.bbapap.2012.10.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 10/05/2012] [Indexed: 12/21/2022]
Abstract
RET is the receptor for glial cell line-derived neurotrophic factor family of ligands (GFLs). It is different from most other members in the receptor tyrosine kinase (RTK) family with the requirement of a co-receptor, GFRα, for ligand recognition and activation. Through the common signal transducer RET, GFLs are crucial for the development and maintenance of distinct sets of central and peripheral neurons, which has led to a series of studies towards understanding the structure, function and signaling mechanisms of GFLs with GFRα and RET receptors. Here I summarize our current understanding of the molecular basis underlying ligand recognition and activation of RET, focusing on the interactions of GFLs with their respective GFRα receptors, the recently determined crystal structure of RET extracellular region and a proposed GFL-GFRα-RET ternary complex model based on extensive structural, biochemical and functional data. This article is part of a Special Issue entitled: Emerging recognition and activation mechanisms of receptor tyrosine kinases.
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Affiliation(s)
- Xinquan Wang
- Center for Structural Biology, School of Life Sciences, Ministry of Education Key Laboratory of Protein Science, Medical Science Building C226, Tsinghua University, Beijing 100084, PR China.
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