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Nikolaev G, Robeva R, Konakchieva R. Membrane Melatonin Receptors Activated Cell Signaling in Physiology and Disease. Int J Mol Sci 2021; 23:ijms23010471. [PMID: 35008896 PMCID: PMC8745360 DOI: 10.3390/ijms23010471] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 02/07/2023] Open
Abstract
The pineal hormone melatonin has attracted great scientific interest since its discovery in 1958. Despite the enormous number of basic and clinical studies the exact role of melatonin in respect to human physiology remains elusive. In humans, two high-affinity receptors for melatonin, MT1 and MT2, belonging to the family of G protein-coupled receptors (GPCRs) have been cloned and identified. The two receptor types activate Gi proteins and MT2 couples additionally to Gq proteins to modulate intracellular events. The individual effects of MT1 and MT2 receptor activation in a variety of cells are complemented by their ability to form homo- and heterodimers, the functional relevance of which is yet to be confirmed. Recently, several melatonin receptor genetic polymorphisms were discovered and implicated in pathology-for instance in type 2 diabetes, autoimmune disease, and cancer. The circadian patterns of melatonin secretion, its pleiotropic effects depending on cell type and condition, and the already demonstrated cross-talks of melatonin receptors with other signal transduction pathways further contribute to the perplexity of research on the role of the pineal hormone in humans. In this review we try to summarize the current knowledge on the membrane melatonin receptor activated cell signaling in physiology and pathology and their relevance to certain disease conditions including cancer.
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Affiliation(s)
- Georgi Nikolaev
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 1504 Sofia, Bulgaria;
- Correspondence:
| | - Ralitsa Robeva
- Department of Endocrinology, Faculty of Medicine, Medical University, 1431 Sofia, Bulgaria;
| | - Rossitza Konakchieva
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 1504 Sofia, Bulgaria;
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2
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Tse LH, Wong YH. Modeling the Heterodimer Interfaces of Melatonin Receptors. Front Cell Neurosci 2021; 15:725296. [PMID: 34690701 PMCID: PMC8529217 DOI: 10.3389/fncel.2021.725296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/16/2021] [Indexed: 11/16/2022] Open
Abstract
Melatonin receptors are Class A G protein-coupled receptors (GPCRs) that regulate a plethora of physiological activities in response to the rhythmic secretion of melatonin from the pineal gland. Melatonin is a key regulator in the control of circadian rhythm and has multiple functional roles in retinal physiology, memory, immunomodulation and tumorigenesis. The two subtypes of human melatonin receptors, termed MT1 and MT2, utilize overlapping signaling pathways although biased signaling properties have been reported in some cellular systems. With the emerging concept of GPCR dimerization, melatonin receptor heterodimers have been proposed to participate in system-biased signaling. Here, we used computational approaches to map the dimerization interfaces of known heterodimers of melatonin receptors, including MT1/MT2, MT1/GPR50, MT2/GPR50, and MT2/5-HT2C. By homology modeling and membrane protein docking analyses, we have identified putative preferred interface interactions within the different pairs of melatonin receptor dimers and provided plausible structural explanations for some of the unique pharmacological features of specific heterodimers previously reported. A thorough understanding of the molecular basis of melatonin receptor heterodimers may enable the development of new therapeutic approaches against aliments involving these heterodimeric receptors.
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Affiliation(s)
- Lap Hang Tse
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, SAR China
| | - Yung Hou Wong
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, SAR China.,State Key Laboratory of Molecular Neuroscience, Molecular Neuroscience Center, Hong Kong University of Science and Technology, Hong Kong, SAR China.,Hong Kong Center for Neurodegenerative Diseases, Hong Kong Science Park, Hong Kong, SAR China
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3
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Nakamura Y, Asama R, Tabata T, Morita K, Maruyama T, Kondo A, Ishii J. Comparative analyses of site-directed mutagenesis of human melatonin MTNR1A and MTNR1B receptors using a yeast fluorescent biosensor. Biotechnol Bioeng 2020; 118:863-876. [PMID: 33095446 DOI: 10.1002/bit.27609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/22/2020] [Accepted: 10/22/2020] [Indexed: 11/08/2022]
Abstract
Melatonin is an indoleamine neurohormone made by the pineal gland. Its receptors, MTNR1A and MTNR1B, are members of the G-protein-coupled receptor (GPCR) family and are involved in sleep, circadian rhythm, and mood disorders, and in the inhibition of cancer growth. These receptors, therefore, represent significant molecular targets for insomnia, circadian sleep disorders, and cancer. The yeast Saccharomyces cerevisiae is an attractive host for assaying agonistic activity for human GPCR. We previously constructed a GPCR-based biosensor employing a high-sensitivity yeast strain that incorporated both a chimeric yeast-human Gα protein and a bright fluorescent reporter gene (ZsGreen). Similar approaches have been used for simple and convenient measurements of various GPCR activities. In the current study, we constructed a fluorescence-based yeast biosensor for monitoring the signaling activation of human melatonin receptors. We used this system to analyze point mutations, including previously unreported mutations of the consensus sequences of MTNR1A and MTNR1B melatonin receptors and compared their effects. Most mutations in the consensus sequences significantly affected the signaling capacities of both receptors, but several mutations showed differences between these subtype receptors. Thus, this yeast biosensor holds promise for revealing the functions of melatonin receptors.
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Affiliation(s)
- Yasuyuki Nakamura
- Engineering Biology Research Center, Kobe University, Kobe, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Ririka Asama
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Takuya Tabata
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Kenta Morita
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Tatsuo Maruyama
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Akihiko Kondo
- Engineering Biology Research Center, Kobe University, Kobe, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan.,Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan.,Center for Sustainable Resource Science, RIKEN, Yokohama, Japan
| | - Jun Ishii
- Engineering Biology Research Center, Kobe University, Kobe, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
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4
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The regulation of skin pigmentation in response to environmental light by pineal Type II opsins and skin melanophore melatonin receptors. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2020; 212:112024. [DOI: 10.1016/j.jphotobiol.2020.112024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/19/2020] [Accepted: 09/05/2020] [Indexed: 11/21/2022]
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5
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Abstract
The pineal gland has a romantic history, from pharaonic Egypt, where it was equated with the eye of Horus, through various religious traditions, where it was considered the seat of the soul, the third eye, etc. Recent incarnations of these notions have suggested that N,N-dimethyltryptamine is secreted by the pineal gland at birth, during dreaming, and at near death to produce out of body experiences. Scientific evidence, however, is not consistent with these ideas. The adult pineal gland weighs less than 0.2 g, and its principal function is to produce about 30 µg per day of melatonin, a hormone that regulates circadian rhythm through very high affinity interactions with melatonin receptors. It is clear that very minute concentrations of N,N-dimethyltryptamine have been detected in the brain, but they are not sufficient to produce psychoactive effects. Alternative explanations are presented to explain how stress and near death can produce altered states of consciousness without invoking the intermediacy of N,N-dimethyltryptamine.
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6
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Suofu Y, Li W, Jean-Alphonse FG, Jia J, Khattar NK, Li J, Baranov SV, Leronni D, Mihalik AC, He Y, Cecon E, Wehbi VL, Kim J, Heath BE, Baranova OV, Wang X, Gable MJ, Kretz ES, Di Benedetto G, Lezon TR, Ferrando LM, Larkin TM, Sullivan M, Yablonska S, Wang J, Minnigh MB, Guillaumet G, Suzenet F, Richardson RM, Poloyac SM, Stolz DB, Jockers R, Witt-Enderby PA, Carlisle DL, Vilardaga JP, Friedlander RM. Dual role of mitochondria in producing melatonin and driving GPCR signaling to block cytochrome c release. Proc Natl Acad Sci U S A 2017; 114:E7997-E8006. [PMID: 28874589 PMCID: PMC5617277 DOI: 10.1073/pnas.1705768114] [Citation(s) in RCA: 278] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are classically characterized as cell-surface receptors transmitting extracellular signals into cells. Here we show that central components of a GPCR signaling system comprised of the melatonin type 1 receptor (MT1), its associated G protein, and β-arrestins are on and within neuronal mitochondria. We discovered that the ligand melatonin is exclusively synthesized in the mitochondrial matrix and released by the organelle activating the mitochondrial MT1 signal-transduction pathway inhibiting stress-mediated cytochrome c release and caspase activation. These findings coupled with our observation that mitochondrial MT1 overexpression reduces ischemic brain injury in mice delineate a mitochondrial GPCR mechanism contributing to the neuroprotective action of melatonin. We propose a new term, "automitocrine," analogous to "autocrine" when a similar phenomenon occurs at the cellular level, to describe this unexpected intracellular organelle ligand-receptor pathway that opens a new research avenue investigating mitochondrial GPCR biology.
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Affiliation(s)
- Yalikun Suofu
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Wei Li
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
- School of Medicine, University of Tsinghua, Beijing, China 100084
| | - Frédéric G Jean-Alphonse
- Laboratory for G-Protein Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Jiaoying Jia
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
- Xiangya Second Hospital, Central South University, Hunan Province, China 410008
| | - Nicolas K Khattar
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Jiatong Li
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
- School of Medicine, University of Tsinghua, Beijing, China 100084
| | - Sergei V Baranov
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Daniela Leronni
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Amanda C Mihalik
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Yanqing He
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
- Xiangya Second Hospital, Central South University, Hunan Province, China 410008
| | - Erika Cecon
- Inserm, U1016, Institut Cochin, 75014 Paris, France
- CNRS UMR 8104, Paris, France
- University of Paris Descartes, 75006 Paris, France
| | - Vanessa L Wehbi
- Laboratory for G-Protein Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - JinHo Kim
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Brianna E Heath
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Oxana V Baranova
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Xiaomin Wang
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Matthew J Gable
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Eric S Kretz
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | | | - Timothy R Lezon
- Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Lisa M Ferrando
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Timothy M Larkin
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Mara Sullivan
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA 15213
| | - Svitlana Yablonska
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Jingjing Wang
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
- School of Medicine, University of Tsinghua, Beijing, China 100084
| | - M Beth Minnigh
- Small Molecule Biomarker Core, University of Pittsburgh, Pittsburgh, PA 15213
| | - Gérald Guillaumet
- Institut de Chimie Organique et Analytique, Universite d'Orleans, UMR CNRS 7311, 45067 Orleans, France
| | - Franck Suzenet
- Institut de Chimie Organique et Analytique, Universite d'Orleans, UMR CNRS 7311, 45067 Orleans, France
| | - R Mark Richardson
- Brain Modulation Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Samuel M Poloyac
- Small Molecule Biomarker Core, University of Pittsburgh, Pittsburgh, PA 15213
| | - Donna B Stolz
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA 15213
| | - Ralf Jockers
- Inserm, U1016, Institut Cochin, 75014 Paris, France
- CNRS UMR 8104, Paris, France
- University of Paris Descartes, 75006 Paris, France
| | | | - Diane L Carlisle
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Jean-Pierre Vilardaga
- Laboratory for G-Protein Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261;
| | - Robert M Friedlander
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213;
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Dubocovich ML, Delagrange P, Krause DN, Sugden D, Cardinali DP, Olcese J. International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, classification, and pharmacology of G protein-coupled melatonin receptors. Pharmacol Rev 2010; 62:343-80. [PMID: 20605968 PMCID: PMC2964901 DOI: 10.1124/pr.110.002832] [Citation(s) in RCA: 400] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The hormone melatonin (5-methoxy-N-acetyltryptamine) is synthesized primarily in the pineal gland and retina, and in several peripheral tissues and organs. In the circulation, the concentration of melatonin follows a circadian rhythm, with high levels at night providing timing cues to target tissues endowed with melatonin receptors. Melatonin receptors receive and translate melatonin's message to influence daily and seasonal rhythms of physiology and behavior. The melatonin message is translated through activation of two G protein-coupled receptors, MT(1) and MT(2), that are potential therapeutic targets in disorders ranging from insomnia and circadian sleep disorders to depression, cardiovascular diseases, and cancer. This review summarizes the steps taken since melatonin's discovery by Aaron Lerner in 1958 to functionally characterize, clone, and localize receptors in mammalian tissues. The pharmacological and molecular properties of the receptors are described as well as current efforts to discover and develop ligands for treatment of a number of illnesses, including sleep disorders, depression, and cancer.
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Affiliation(s)
- Margarita L Dubocovich
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo State University of New York, 3435 Main Street, Buffalo, NY 14214, USA.
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Cogé F, Guenin SP, Fery I, Migaud M, Devavry S, Slugocki C, Legros C, Ouvry C, Cohen W, Renault N, Nosjean O, Malpaux B, Delagrange P, Boutin JA. The end of a myth: cloning and characterization of the ovine melatonin MT(2) receptor. Br J Pharmacol 2009; 158:1248-62. [PMID: 19814723 DOI: 10.1111/j.1476-5381.2009.00453.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND PURPOSE For many years, it was suspected that sheep expressed only one melatonin receptor (closely resembling MT(1) from other mammal species). Here we report the cloning of another melatonin receptor, MT(2), from sheep. EXPERIMENTAL APPROACH Using a thermo-resistant reverse transcriptase and polymerase chain reaction primer set homologous to the bovine MT(2) mRNA sequence, we have cloned and characterized MT(2) receptors from sheep retina. KEY RESULTS The ovine MT(2) receptor presents 96%, 72% and 67% identity with cattle, human and rat respectively. This MT(2) receptor stably expressed in CHO-K1 cells showed high-affinity 2[(125)I]-iodomelatonin binding (K(D)= 0.04 nM). The rank order of inhibition of 2[(125)I]-iodomelatonin binding by melatonin, 4-phenyl-2-propionamidotetralin and luzindole was similar to that exhibited by MT(2) receptors of other species (melatonin > 4-phenyl-2-propionamidotetralin > luzindole). However, its pharmacological profile was closer to that of rat, rather than human MT(2) receptors. Functionally, the ovine MT(2) receptors were coupled to G(i) proteins leading to inhibition of adenylyl cyclase, as the other melatonin receptors. In sheep brain, MT(2) mRNA was expressed in pars tuberalis, choroid plexus and retina, and moderately in mammillary bodies. Real-time polymerase chain reaction showed that in sheep pars tuberalis, premammillary hypothalamus and mammillary bodies, the temporal pattern of expression of MT(1) and MT(2) mRNA was not parallel in the three tissues. CONCLUSION AND IMPLICATIONS Co-expression of MT(1) and MT(2) receptors in all analysed sheep brain tissues suggests that MT(2) receptors may participate in melatonin regulation of seasonal anovulatory activity in ewes by modulating MT(1) receptor action.
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Affiliation(s)
- F Cogé
- Pharmacologie Moléculaire et Cellulaire, Institut de Recherches SERVIER, Suresnes, France
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Chugunov AO, Farce A, Chavatte P, Efremov RG. Differences in Binding Sites of Two Melatonin Receptors Help to Explain Their Selectivity to Some Melatonin Analogs: A Molecular Modeling Study. J Biomol Struct Dyn 2006; 24:91-107. [PMID: 16928133 DOI: 10.1080/07391102.2006.10507103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Numerous diseases have been linked to the malfunction of G-protein coupled receptors (GPCRs). Their adequate treatment requires rational design of new high-affinity and high-selectivity drugs targeting these receptors. In this work, we report three-dimensional models of the human MT(1) and MT(2) melatonin receptors, members of the GPCR family. The models are based on the X-ray structure of bovine rhodopsin. The computational approach employs an original procedure for optimization of receptor-ligand structures. It includes rotation of one of the transmembrane alpha-helices around its axis with simultaneous assessment of quality of the resulting complexes according to a number of criteria we have developed for this purpose. The optimal geometry of the receptor-ligand binding is selected based on the analysis of complementarity of hydrophobic/hydrophilic properties between the ligand and its protein environment in the binding site. The elaborated "optimized" models are employed to explore the details of protein-ligand interactions for melatonin and a number of its analogs with known affinity to MT(1) and MT(2) receptors. The models permit rationalization of experimental data, including those that were not used in model building. The perspectives opened by the constructed models and by the optimization procedure in the design of new drugs are discussed.
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Affiliation(s)
- Anton O Chugunov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, GSP Moscow, 117997, Russia.
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Levoye A, Dam J, Ayoub MA, Guillaume JL, Couturier C, Delagrange P, Jockers R. The orphan GPR50 receptor specifically inhibits MT1 melatonin receptor function through heterodimerization. EMBO J 2006; 25:3012-23. [PMID: 16778767 PMCID: PMC1500982 DOI: 10.1038/sj.emboj.7601193] [Citation(s) in RCA: 235] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 05/18/2006] [Indexed: 12/21/2022] Open
Abstract
One-third of the approximately 400 nonodorant G protein-coupled receptors (GPCRs) are still orphans. Although a considerable number of these receptors are likely to transduce cellular signals in response to ligands that remain to be identified, they may also have ligand-independent functions. Several members of the GPCR family have been shown to modulate the function of other receptors through heterodimerization. We show that GPR50, an orphan GPCR, heterodimerizes constitutively and specifically with MT(1) and MT(2) melatonin receptors, using biochemical and biophysical approaches in intact cells. Whereas the association between GPR50 and MT(2) did not modify MT(2) function, GPR50 abolished high-affinity agonist binding and G protein coupling to the MT(1) protomer engaged in the heterodimer. Deletion of the large C-terminal tail of GPR50 suppressed the inhibitory effect of GPR50 on MT(1) without affecting heterodimerization, indicating that this domain regulates the interaction of regulatory proteins to MT(1). Pairing orphan GPCRs to potential heterodimerization partners might be of clinical importance and may become a general strategy to better understand the function of orphan GPCRs.
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MESH Headings
- Arrestins/metabolism
- Cell Line
- Dimerization
- Down-Regulation
- Humans
- Ligands
- Melatonin/metabolism
- Mutation
- Nerve Tissue Proteins/biosynthesis
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/physiology
- Protein Binding
- Receptor, Melatonin, MT1/antagonists & inhibitors
- Receptor, Melatonin, MT1/physiology
- Receptor, Melatonin, MT2/antagonists & inhibitors
- Receptor, Melatonin, MT2/physiology
- Receptors, G-Protein-Coupled/biosynthesis
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/physiology
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/physiology
- Signal Transduction
- beta-Arrestins
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Affiliation(s)
- Angélique Levoye
- Department of Cell Biology, Institut Cochin, Paris, France
- Inserm U567, Paris, France
- CNRS, UMR 8104, Paris, France
- Université Paris 5, Faculté de Médecine René Descartes, UM 3, Paris, France
| | - Julie Dam
- Department of Cell Biology, Institut Cochin, Paris, France
- Inserm U567, Paris, France
- CNRS, UMR 8104, Paris, France
- Université Paris 5, Faculté de Médecine René Descartes, UM 3, Paris, France
| | - Mohammed A Ayoub
- Department of Cell Biology, Institut Cochin, Paris, France
- Inserm U567, Paris, France
- CNRS, UMR 8104, Paris, France
- Université Paris 5, Faculté de Médecine René Descartes, UM 3, Paris, France
| | - Jean-Luc Guillaume
- Department of Cell Biology, Institut Cochin, Paris, France
- Inserm U567, Paris, France
- CNRS, UMR 8104, Paris, France
- Université Paris 5, Faculté de Médecine René Descartes, UM 3, Paris, France
| | - Cyril Couturier
- Department of Cell Biology, Institut Cochin, Paris, France
- Inserm U567, Paris, France
- CNRS, UMR 8104, Paris, France
- Université Paris 5, Faculté de Médecine René Descartes, UM 3, Paris, France
| | | | - Ralf Jockers
- Department of Cell Biology, Institut Cochin, Paris, France
- Inserm U567, Paris, France
- CNRS, UMR 8104, Paris, France
- Université Paris 5, Faculté de Médecine René Descartes, UM 3, Paris, France
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11
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Zhang Y, DeVries ME, Skolnick J. Structure modeling of all identified G protein-coupled receptors in the human genome. PLoS Comput Biol 2006; 2:e13. [PMID: 16485037 PMCID: PMC1364505 DOI: 10.1371/journal.pcbi.0020013] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Accepted: 01/11/2005] [Indexed: 12/22/2022] Open
Abstract
G protein–coupled receptors (GPCRs), encoded by about 5% of human genes, comprise the largest family of integral membrane proteins and act as cell surface receptors responsible for the transduction of endogenous signal into a cellular response. Although tertiary structural information is crucial for function annotation and drug design, there are few experimentally determined GPCR structures. To address this issue, we employ the recently developed threading assembly refinement (TASSER) method to generate structure predictions for all 907 putative GPCRs in the human genome. Unlike traditional homology modeling approaches, TASSER modeling does not require solved homologous template structures; moreover, it often refines the structures closer to native. These features are essential for the comprehensive modeling of all human GPCRs when close homologous templates are absent. Based on a benchmarked confidence score, approximately 820 predicted models should have the correct folds. The majority of GPCR models share the characteristic seven-transmembrane helix topology, but 45 ORFs are predicted to have different structures. This is due to GPCR fragments that are predominantly from extracellular or intracellular domains as well as database annotation errors. Our preliminary validation includes the automated modeling of bovine rhodopsin, the only solved GPCR in the Protein Data Bank. With homologous templates excluded, the final model built by TASSER has a global Cα root-mean-squared deviation from native of 4.6 Å, with a root-mean-squared deviation in the transmembrane helix region of 2.1 Å. Models of several representative GPCRs are compared with mutagenesis and affinity labeling data, and consistent agreement is demonstrated. Structure clustering of the predicted models shows that GPCRs with similar structures tend to belong to a similar functional class even when their sequences are diverse. These results demonstrate the usefulness and robustness of the in silico models for GPCR functional analysis. All predicted GPCR models are freely available for noncommercial users on our Web site (http://www.bioinformatics.buffalo.edu/GPCR). G protein–coupled receptors (GPCRs) are a large superfamily of integral membrane proteins that transduce signals across the cell membrane. Because of the breadth and importance of the physiological roles undertaken by the GPCR family, many of its members are important pharmacological targets. Although the knowledge of a protein's native structure can provide important insight into understanding its function and for the design of new drugs, the experimental determination of the three-dimensional structure of GPCR membrane proteins has proved to be very difficult. This is demonstrated by the fact that there is only one solved GPCR structure (from bovine rhodopsin) deposited in the Protein Data Bank library. In contrast, there are no human GPCR structures in the Protein Data Bank. To address the need for the tertiary structures of human GPCRs, using just sequence information, the authors use a newly developed threading-assembly-refinement method to generate models for all 907 registered GPCRs in the human genome. About 820 GPCRs are anticipated to have correct topology and transmembrane helix arrangement. A subset of the resulting models is validated by comparison with mutagenesis experimental data, and consistent agreement is demonstrated.
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Affiliation(s)
- Yang Zhang
- Center of Excellence in Bioinformatics, University at Buffalo, Buffalo, New York, United States of America
| | - Mark E DeVries
- Center of Excellence in Bioinformatics, University at Buffalo, Buffalo, New York, United States of America
| | - Jeffrey Skolnick
- Center of Excellence in Bioinformatics, University at Buffalo, Buffalo, New York, United States of America
- * To whom correspondence should be addressed. E-mail:
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12
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Abstract
Melatonin, dubbed the hormone of darkness, is known to regulate a wide variety of physiological processes in mammals. This review describes well-defined functional responses mediated through activation of high-affinity MT1 and MT2 G protein-coupled receptors viewed as potential targets for drug discovery. MT1 melatonin receptors modulate neuronal firing, arterial vasocon-striction, cell proliferation in cancer cells, and reproductive and metabolic functions. Activation of MT2 melatonin receptors phase shift circadian rhythms of neuronal firing in the suprachiasmatic nucleus, inhibit dopamine release in retina, induce vasodilation and inhibition of leukocyte rolling in arterial beds, and enhance immune responses. The melatonin-mediated responses elicited by activation of MT1 and MT2 native melatonin receptors are dependent on circadian time, duration and mode of exposure to endogenous or exogenous melatonin, and functional receptor sensitivity. Together, these studies underscore the importance of carefully linking each melatonin receptor type to specific functional responses in target tissues to facilitate the design and development of novel therapeutic agent.
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Affiliation(s)
- Margarita L Dubocovich
- Department of Molecular Pharmacology & Biological Chemistry, Northwestern University Feinberg School of Medicine Center for Drug Discovery and Chemical Biology, Chicago, IL 60611, USA.
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13
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Kokkola T, Salo OMH, Poso A, Laitinen JT. The functional role of cysteines adjacent to the NRY motif of the human MT1 melatonin receptor. J Pineal Res 2005; 39:1-11. [PMID: 15978051 DOI: 10.1111/j.1600-079x.2004.00204.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
All G protein-coupled melatonin receptors have two conserved cysteines in the interphase between transmembrane helix III and the second intracellular loop, in the region assumed important in receptor/G protein coupling. The cysteines are also potential targets of receptor S-nitrosylation. The effects of site-directed mutagenesis of these cysteines in the human MT1 melatonin receptor were investigated. The cysteines were mutated into serines either individually or as a pair and stable Chinese hamster ovary cell lines expressing the wild-type and mutant MT1 receptors were created. Receptor expression level, subcellular localization, ligand binding and G protein activation of the cell lines were analyzed. Serine substitution of C127 (Cys(3.52)) did not affect the ligand binding affinity and agonist potency but had an influence on receptor trafficking and G protein activation capacity. Serine substitution of C130 (Cys(3.55)) resulted in a decrease in the potency of melatonin to activate G proteins. When both cysteines were mutated into serines, normal MT1 receptor binding and activation were abolished. Computer modeling revealed that the mutations did not change the structure of the ligand binding pocket. Cysteine S-nitrosylation had no influence on G protein activation through MT1 receptors. Taken together, these data show that the two conserved cysteines in the end of transmembrane domain III of the MT1 melatonin receptor, especially C130 (Cys(3.55)), are needed for normal G protein activation and receptor trafficking.
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Affiliation(s)
- Tarja Kokkola
- Department of Physiology, University of Kuopio, Kuopio, Finland.
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Bowes TJ, Gupta RS. Induction of mitochondrial fusion by cysteine-alkylators ethacrynic acid and N-ethylmaleimide. J Cell Physiol 2005; 202:796-804. [PMID: 15389563 DOI: 10.1002/jcp.20178] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mitochondrial fusion and fission are important aspects of eukaryotic cell function that permit the adoption of varied mitochondrial morphologies depending upon cellular physiology. We previously observed that ethacrynic acid (EA) induced mitochondrial fusion in cultured BSC-1 and CHO/wt cells. However, the mechanism responsible for it was not clear since EA has a number of known cellular effects including glutathione (GSH) depletion and alkylation of cysteine residues. To gain insight, we have tested the effects of a variety of compounds on EA induced cellular toxicity and mitochondrial fusion. N-acetyl cysteine (NAC), a GSH precursor, was found to abrogate both the toxic and fusion-inductive effects, whereas diethylmaleate (dEM), a GSH depletor, potentiated both these effects in a dose-dependent manner. However, treatment with dEM alone, which depleted GSH to the same degree as EA, did not induce mitochondrial fusion. These results indicate that although detoxification of EA via formation of GSH conjugates is dependant upon GSH levels, the depletion of GSH by EA is not responsible for its effect on mitochondrial fusion. Dihydro-EA (DH-EA), a saturated EA analogue, lacked EA's toxicity and effect on fusion, indicating that the alpha,beta-unsaturated ketone is central to its observed effects. N-ethylmaleimide (NEM), another well-known cysteine-alkylator, also induced mitochondrial fusion at near toxic concentrations. These data suggests that cysteine-alkylation is the causative factor for fusion and toxicity. In live BSC-1 cells, EA induced fusion of mitochondria occurred very rapidly (<20 min), which suggests that it is inducing fusion by modifying certain critical cysteine residue(s) in proteins involved in the process.
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Affiliation(s)
- Timothy J Bowes
- Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada
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15
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Abstract
The melatonin receptor family is a small group of receptors within the G protein-coupled receptor (GPCR) superfamily. The group comprises of three subtypes which bind melatonin and one member, the melatonin related receptor (MRR), that shares >40% sequence identity with the other melatonin receptors but does not bind melatonin. Identification of two subtypes expressed in the mouse suprachiasmatic nucleus, one of which (MT1) inhibits neuronal firing and the other (MT2) mediating the phase advancing properties of melatonin has given renewed interest to the development of subtype specific compounds for each of the mammalian melatonin receptors. Towards this goal site-directed and chimaeric receptor mutagenesis studies have been performed which have provided some insight into the structure-function relationships of the melatonin receptors. Furthermore, these studies may lead to the identification of the ligand for the orphan MRR.
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Affiliation(s)
- Perry Barrett
- Molecular Endocrinology Group, Division of Energy balance and Obesity, Rowett Research Institute, Aberdeen, UK.
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16
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Abstract
Melatonin mediates its physiological effects through activation of high affinity G protein-coupled receptors. The vertebrate MT(1), MT(2) and Mel(1c) melatonin receptors are molecularly and pharmacologically distinct. Three molecular models of melatonin recognition for the MT(1) and/or Mel(1c) melatonin receptors have been proposed. To determine if these models applied to the MT(2) melatonin receptor, we mutated seven conserved residues to alanine in the hMT(2) melatonin receptor and expressed the receptors in HEK-293 cells. Competition of melatonin for 2-[125I]-iodomelatonin binding revealed that mutation of Asn 16 in TM4 or His 7 in TM5 of the hMT(2) melatonin receptor significantly decreased the binding affinity for melatonin when compared with wild-type. In addition, competition of 4P-ADOT, N-acetyltryptamine, luzindole, and 5-methoxytryptophol for 2-[125I]-iodomelatonin binding suggested Asn 16 in TM4 may facilitate binding of the 5-methoxy group of the melatonin molecule to the hMT(2) melatonin receptor. Trp 13 or Phe 6 in TM6 while not critical for melatonin binding, may interact with aromatic regions of luzindole and 4P-ADOT. Mutation of Ser 8 or Ser 12 in TM3, or Ser 6 in TM7 did not affect the affinity of melatonin for competition with 2-[125I]-iodomelatonin to the hMT(2) melatonin receptor, although equivalent serines (Ser 8 and Ser 12 in TM3) were reported to be critical for melatonin binding to the hMT(1) melatonin receptor. Thus these results are the first to identify residues within the transmembrane regions of the hMT(2) melatonin receptor critical for melatonin binding, highlighting potential structural differences between the MT(1) and MT(2) melatonin receptor binding pockets.
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MESH Headings
- Amino Acid Sequence
- Cells, Cultured
- Humans
- Melatonin/metabolism
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Melatonin
- Sequence Homology, Amino Acid
- Transfection
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Affiliation(s)
- Matthew J Gerdin
- Department of Molecular Pharmacology and Biological Chemistry (S215), The Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611-3008, USA
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Witt-Enderby PA, Bennett J, Jarzynka MJ, Firestine S, Melan MA. Melatonin receptors and their regulation: biochemical and structural mechanisms. Life Sci 2003; 72:2183-98. [PMID: 12628439 DOI: 10.1016/s0024-3205(03)00098-5] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is growing evidence demonstrating the complexity of melatonin's role in modulating a diverse number of physiological processes. This complexity could be attributed to the fact that melatonin receptors belong to two distinct classes of proteins, that is, the G-protein coupled receptor superfamily (MT(1), MT(2)) and the quinone reductase enzyme family (MT(3)) which makes them unique at the molecular level. Also, within the G-protein coupled receptor family of proteins, the MT(1) and MT(2) receptors can couple to multiple and distinct signal transduction cascades whose activation can lead to unique cellular responses. Also, throughout the 24-hour cycle, the receptors' sensitivity to specific cues fluctuates and this sensitivity can be modulated in a homologous fashion, that is, by melatonin itself, and in a heterologous manner, that is, by other cues including the photoperiod or estrogen. This sensitivity of response may reflect changes in melatonin receptor density that also occurs throughout the 24-hour light/dark cycle but out of phase with circulating melatonin levels. The mechanisms that underlie the changes in melatonin receptor density and function are still not well-understood, but data is beginning to show that transcriptional events and G-protein uncoupling may be involved. Even though this area of research is still in its infancy, great strides are being made everyday in elucidating the mechanisms that underlie melatonin receptor function and regulation. The focus of this review is to highlight some of these discoveries in an attempt to reveal the uniqueness of the melatonin receptor family while at the same time provide thought-provoking ideas to further advance this area of research. Thus, a brief overview of each of the mammalian melatonin receptor subtypes and the signal transduction cascades to which they couple will be discussed with a greater emphasis placed on the mechanisms underlying their regulation and the domains within the receptors essential for proper signaling.
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Affiliation(s)
- Paula A Witt-Enderby
- Division of Pharmaceutical Sciences, Duquesne University School of Pharmacy, 421 Mellon Hall, Pittsburgh, PA 15282, USA.
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