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Laitakari A, Liu L, Frimurer TM, Holst B. The Zinc-Sensing Receptor GPR39 in Physiology and as a Pharmacological Target. Int J Mol Sci 2021; 22:ijms22083872. [PMID: 33918078 PMCID: PMC8070507 DOI: 10.3390/ijms22083872] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/31/2021] [Accepted: 04/06/2021] [Indexed: 12/16/2022] Open
Abstract
The G-protein coupled receptor GPR39 is abundantly expressed in various tissues and can be activated by changes in extracellular Zn2+ in physiological concentrations. Previously, genetically modified rodent models have been able to shed some light on the physiological functions of GPR39, and more recently the utilization of novel synthetic agonists has led to the unraveling of several new functions in the variety of tissues GPR39 is expressed. Indeed, GPR39 seems to be involved in many important metabolic and endocrine functions, but also to play a part in inflammation, cardiovascular diseases, saliva secretion, bone formation, male fertility, addictive and depression disorders and cancer. These new discoveries offer opportunities for the development of novel therapeutic approaches against many diseases where efficient therapeutics are still lacking. This review focuses on Zn2+ as an endogenous ligand as well as on the novel synthetic agonists of GPR39, placing special emphasis on the recently discovered physiological functions and discusses their pharmacological potential.
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Affiliation(s)
- Anna Laitakari
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
| | - Lingzhi Liu
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Thomas M. Frimurer
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
| | - Birgitte Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
- Correspondence:
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Zhang L, Song J, Zang Z, Tang H, Li W, Lai S, Deng C. Adaptive evolution of GPR39 in diverse directions in vertebrates. Gen Comp Endocrinol 2020; 299:113610. [PMID: 32916170 DOI: 10.1016/j.ygcen.2020.113610] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/27/2020] [Accepted: 08/30/2020] [Indexed: 02/08/2023]
Abstract
G protein-coupled receptors (GPCRs) play an important role in physiology and disease and represent productive drug targets. Orphan GPCRs, which have unknown endogenous ligands, are considered drug targets and consequently have attracted great interest in identifying their endogenous cognate ligands for deorphanization. However, additional studies have shown that GPCRs, including many orphan GPCRs, can constitutively activate G protein signaling in a ligand-independent manner. GPR39 is such an orphan GPCR with constitutive activity. Here, we performed a phylogenetic and selection analysis of GPR39 in vertebrates, and we found that GPR39 underwent positive selection in different branches of vertebrates. Using luciferase reporter assays, we demonstrated that human, frog and chicken GPR39 can constitutively activate Gq and G12 signaling pathways in a ligand-independent manner. Zebrafish GPR39 can constitutively activate Gs, Gq and G12 signaling pathways in a ligand-independent manner. We further found that the zebrafish-H2967.35 site is crucial for the activity of the Gs signaling pathway. In addition, our mutagenesis studies indicated that the positive selection sites of GPR39 from different species had important effects on the constitutive activity of the receptor. Our results revealed the adaptive evolution of GPR39 in diverse directions, which led to differences in constitutive activity.
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Affiliation(s)
- Lina Zhang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Jingjing Song
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Zhuqing Zang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Huihao Tang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Wei Li
- Department of Dermatovenereology, Rare Disease Center, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang Street, Chengdu, Sichuan 610041, China
| | - Shanshan Lai
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| | - Cheng Deng
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
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GI functions of GPR39: novel biology. Curr Opin Pharmacol 2012; 12:647-52. [PMID: 22884904 DOI: 10.1016/j.coph.2012.07.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/24/2012] [Accepted: 07/27/2012] [Indexed: 01/20/2023]
Abstract
GPR39 is an orphan GPCR receptor belonging to the ghrelin/motilin receptor subfamily. The receptor is constitutively active and Zn(2+) is a physiological agonist of GPR39. The receptor is emerging as an important regulator of gastrointestinal motility and secretion. Although GPR39 does not seem to be involved in the regulation of food intake, contradictory results are available on the role of GPR39 in the regulation of body weight. A well-established stimulatory role for GPR39 has been defined in insulin secretion which makes the receptor an attractive target for the treatment of type 1 or 2 diabetes. GPR39 signaling also inhibits apoptosis and mediates neural synaptic signaling. Novel ligands of GPR39 are warranted to reveal the main physiological role of this receptor.
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Yamamoto I, Nakao N, Kaiya H, Miyazato M, Tsushima N, Arai T, Tanaka M. Two chicken neuromedin U receptors: characterization of primary structure, biological activity and tissue distribution. Gen Comp Endocrinol 2011; 174:116-23. [PMID: 21878335 DOI: 10.1016/j.ygcen.2011.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 08/06/2011] [Accepted: 08/08/2011] [Indexed: 11/29/2022]
Abstract
Neuromedin U (NMU) is a bioactive peptide that is involved in a variety of physiological functions. Two of its receptors, NMUR1 and NMUR2, have been identified and characterized in mammals. In this study, we performed cDNA cloning of chicken NMUR1 and NMUR2, and characterized their primary structure, biological activity, and expression patterns in chicken tissues. The chicken NMUR1 and NMUR2 cDNAs encoded 438 and 395 amino acid sequences, respectively. Chicken NMUR1 showed 54.8%-56.5% sequence identity with human, rat, and mouse NMUR1, and NMUR2 shared 67.3%-70.1% sequence identity with mammalian orthologs. Both chicken receptors have typical characteristics of G-protein-coupled receptors with seven transmembrane domains and the D/ERY motif. An increase in intracellular Ca(2+) mobilization was observed in HEK293 cells transfected with chicken NMUR1 or NMUR2 cDNA and treated with chicken or rat NMU. Real-time PCR analysis revealed that NMUR1 mRNA was preferentially expressed in the intestinal tissues such as the duodenum, jejunum, ileum, cecum, and colon/rectum, and brain regions such as the midbrain and optic lobe, and the ovary in adult hens. NMUR2 mRNA was exclusively expressed in the brain regions such as the cerebrum and midbrain. These results indicate that NMUR1 and NMUR2 mRNAs, which encode functional receptor proteins, are expressed in chicken tissues with different distribution patterns.
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Affiliation(s)
- Ichiro Yamamoto
- Department of Veterinary Science, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-8602, Japan
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Popovics P, Stewart AJ. GPR39: a Zn(2+)-activated G protein-coupled receptor that regulates pancreatic, gastrointestinal and neuronal functions. Cell Mol Life Sci 2011; 68:85-95. [PMID: 20812023 PMCID: PMC11114682 DOI: 10.1007/s00018-010-0517-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/16/2010] [Accepted: 08/17/2010] [Indexed: 10/19/2022]
Abstract
GPR39 is a vertebrate G protein-coupled receptor related to the ghrelin/neurotensin receptor subfamily. The receptor is expressed in a range of tissues including the pancreas, gut/gastrointestinal tract, liver, kidney and in some regions of the brain. GPR39 was initially thought to be the cognitive receptor for the peptide hormone, obestatin. However, subsequent in vitro studies have failed to demonstrate binding of this peptide to the receptor. Zn(2+) has been shown to be a potent stimulator of GPR39 activity via the Gα(q), Gα(12/13) and Gα(s) pathways. The potency and specificity of Zn(2+) in activating GPR39 suggest it to be a physiologically important agonist. GPR39 is now emerging as an important transducer of autocrine and paracrine Zn(2+) signals, impacting upon cellular processes such as insulin secretion, gastric emptying, neurotransmission and epithelial repair. This review focuses on the molecular, structural and biological properties of GPR39 and its various physiological functions.
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Affiliation(s)
- Petra Popovics
- School of Medicine, University of St Andrews, Medical and Biological Sciences Building, St Andrews, Fife KY16 9TF UK
| | - Alan J. Stewart
- School of Medicine, University of St Andrews, Medical and Biological Sciences Building, St Andrews, Fife KY16 9TF UK
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The avian proghrelin system. INTERNATIONAL JOURNAL OF PEPTIDES 2010; 2010. [PMID: 20798876 PMCID: PMC2925213 DOI: 10.1155/2010/749401] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 11/06/2009] [Indexed: 11/17/2022]
Abstract
To understand how the proghrelin system functions in regulating growth hormone release and food intake as well as defining its pleiotropic roles in such diverse physiological processes as energy homeostasis, gastrointestinal tract function and reproduction require detailed knowledge of the structure and function of the components that comprise this system. These include the preproghrelin gene that encodes the proghrelin precursor protein from which two peptide hormones, ghrelin and obestatin, are derived and the cognate receptors that bind proghrelin-derived peptides to mediate their physiological actions in different tissues. Also key to the functioning of this system is the posttranslational processing of the proghrelin precursor protein and the individual peptides derived from it. While this system has been intensively studied in a variety of animal species and humans over the last decade, there has been considerably less investigation of the avian proghrelin system which exhibits some unique differences compared to mammals. This review summarizes what is currently known about the proghrelin system in birds and offers new insights into the nature and function of this important endocrine system. Such information facilitates cross-species comparisons and contributes to our understanding of the evolution of the proghrelin system.
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Dong XY, He JM, Tang SQ, Li HY, Jiang QY, Zou XT. Is GPR39 the natural receptor of obestatin? Peptides 2009; 30:431-8. [PMID: 18977259 DOI: 10.1016/j.peptides.2008.09.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 08/25/2008] [Accepted: 09/25/2008] [Indexed: 12/15/2022]
Abstract
GPR39, an orphan receptor belonging to the family of G protein-coupled receptors, was originally reported to be the receptor of obestatin. However recently, numerous reports have questioned this conclusion. In mammals, GPR39 was reported to be involved in the regulation of gastrointestinal and the metabolic functions. In this article, a latest and brief review on the receptor family, structure, distribution and physiological functions of GPR39 has been reported.
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Affiliation(s)
- Xiao-Ying Dong
- College of Yingdong Bioengineering, Shaoguan University, Daxue Avenue, Zhenjiang District, Shaoguan 512005, China
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