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Hao Y, Xing L, Wang Z, Cai J, Toldrá F, Zhang W. Study on the anti-inflammatory activity of the porcine bone collagen peptides prepared by ultrasound-assisted enzymatic hydrolysis. ULTRASONICS SONOCHEMISTRY 2023; 101:106697. [PMID: 37984208 PMCID: PMC10696096 DOI: 10.1016/j.ultsonch.2023.106697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/18/2023] [Accepted: 11/13/2023] [Indexed: 11/22/2023]
Abstract
In this study, the effects of ultrasound-assisted enzymatic hydrolysis on the extraction of anti-inflammatory peptides from porcine bone collagen were investigated. The results showed that ultrasound treatment increased the content of α-helix while decreased β-chain and random coil, promoted generation of small molecular peptides. Ultrasound-assisted enzymatic hydrolysis improved the peptide content, enhanced ABTS+ radical scavenging and ferrous ion chelating ability than non-ultrasound group. At the ultrasonic power of 450 W (20 min), peptides possessed significant anti-inflammatory activity, where the releasing of interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) was all suppressed in lipopolysaccharide (LPS) induced RAW264.7 cells. After the analysis with LC-MS/MS, eight peptides with potential anti-inflammatory activities were selected by the PeptideRanker and molecular docking. In general, the ultrasound-assisted enzymatic hydrolysis was an effective strategy to extract the bioactive peptides from porcine bone, and the inflammatory regulation capacity of bone collagen sourced peptides was firstly demonstrated.
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Affiliation(s)
- Yuejing Hao
- State Key Laboratory of Meat Quality Control and Cultured Meat Development, MOE, Jiangsu Synergetic Innovation Center of Meat Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Lujuan Xing
- State Key Laboratory of Meat Quality Control and Cultured Meat Development, MOE, Jiangsu Synergetic Innovation Center of Meat Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zixu Wang
- State Key Laboratory of Meat Quality Control and Cultured Meat Development, MOE, Jiangsu Synergetic Innovation Center of Meat Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiaming Cai
- State Key Laboratory of Meat Quality Control and Cultured Meat Development, MOE, Jiangsu Synergetic Innovation Center of Meat Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Fidel Toldrá
- Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Avenue Agustín Escardino 7, Paterna, Valencia 46980, Spain
| | - Wangang Zhang
- State Key Laboratory of Meat Quality Control and Cultured Meat Development, MOE, Jiangsu Synergetic Innovation Center of Meat Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
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2
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Guha S, Paul C, Alvarez S, Mine Y, Majumder K. Dietary γ-Glutamyl Valine Ameliorates TNF-α-Induced Vascular Inflammation via Endothelial Calcium-Sensing Receptors. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:9139-9149. [PMID: 32786865 PMCID: PMC8012099 DOI: 10.1021/acs.jafc.0c04526] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
γ-Glutamyl valine (γ-EV), commonly found in edible beans, was shown to reduce gastrointestinal inflammation via activation of calcium-sensing receptors (CaSRs). The present study aimed to evaluate the efficacy of γ-EV in modulating the tumor necrosis factor-α-induced inflammatory responses in endothelial cells (ECs) via CaSR-mediated pathways. Human aortic ECs (HAoECs) were pretreated (2 h) with γ-EV (0.01, 0.1, and 1 mM). 1 mM pretreatment of γ-EV significantly reduced the upregulation of inflammatory adhesion molecules, VCAM-1 and E-selectin, by 44.56 and 57.41%, respectively. The production of cytokines IL-8 and IL-6 was significantly reduced by 40 and 51%, respectively, with 1 mM pretreatment of γ-EV. Similarly, there was a significant reduction in chemokine MCP-1 from a positive control of 9.70 ± 0.52 to 6.6 ± 0.43 ng/mL, after γ-EV treatment. The anti-inflammatory effect of γ-EV was attenuated by the treatment of the CaSR-specific inhibitor, NPS-2143, suggesting the involvement of CaSR-mediated pathways. Further studies identified the critical role of key modulators, such as β-arrestin2 and cyclic adenosine monophosphate response element-binding protein, in mediating the CaSR-dependent anti-inflammatory effect of γ-EV. Finally, the transport efficiency of γ-EV was evaluated through a monolayer of intestinal epithelial cells (Caco-2), and the apparent permeability (Papp) of the peptide was found to be 1.56 × 10-6 cm/s.
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Affiliation(s)
- Snigdha Guha
- Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln 68588, Nebraska, United States
| | - Catherine Paul
- Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln 68588, Nebraska, United States
| | - Sophie Alvarez
- Proteomics and Metabolomics Facility, Nebraska Center for Biotechnology, University of Nebraska-Lincoln, Lincoln 68588, Nebraska, United States
| | - Yoshinori Mine
- Department of Food Science, University of Guelph, Guelph N1G2W1, Ontario, Canada
| | - Kaustav Majumder
- Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln 68588, Nebraska, United States
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3
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Llinas Del Torrent C, Pérez-Benito L, Tresadern G. Computational Drug Design Applied to the Study of Metabotropic Glutamate Receptors. Molecules 2019; 24:molecules24061098. [PMID: 30897742 PMCID: PMC6470756 DOI: 10.3390/molecules24061098] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/15/2019] [Accepted: 03/18/2019] [Indexed: 11/16/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors are a family of eight GPCRs that are attractive drug discovery targets to modulate glutamate action and response. Here we review the application of computational methods to the study of this family of receptors. X-ray structures of the extracellular and 7-transmembrane domains have played an important role to enable structure-based modeling approaches, whilst we also discuss the successful application of ligand-based methods. We summarize the literature and highlight the areas where modeling and experiment have delivered important understanding for mGlu receptor drug discovery. Finally, we offer suggestions of future areas of opportunity for computational work.
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Affiliation(s)
- Claudia Llinas Del Torrent
- Laboratori de Medicina Computacional Unitat de Bioestadistica, Facultat de Medicina, Universitat Autónoma de Barcelona, 08193 Bellaterra, Spain.
| | - Laura Pérez-Benito
- Computational Chemistry, Janssen Research & Development, Janssen Pharmaceutica N. V., Turnhoutseweg 30, B-2340 Beerse, Belgium.
| | - Gary Tresadern
- Computational Chemistry, Janssen Research & Development, Janssen Pharmaceutica N. V., Turnhoutseweg 30, B-2340 Beerse, Belgium.
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4
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Johnson EC. N-Acetylaspartylglutamate is not demonstrated to be a selective mGlu3 receptor agonist. J Neurochem 2011; 119:896-8. [DOI: 10.1111/j.1471-4159.2011.07480.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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5
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Broadhead GK, Mun HC, Avlani VA, Jourdon O, Church WB, Christopoulos A, Delbridge L, Conigrave AD. Allosteric modulation of the calcium-sensing receptor by gamma-glutamyl peptides: inhibition of PTH secretion, suppression of intracellular cAMP levels, and a common mechanism of action with L-amino acids. J Biol Chem 2010; 286:8786-97. [PMID: 21187282 DOI: 10.1074/jbc.m110.149724] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
γ-Glutamyl peptides were identified previously as novel positive allosteric modulators of Ca(2+)(o)-dependent intracellular Ca(2+) mobilization in HEK-293 cells that bind in the calcium-sensing receptor VFT domain. In the current study, we investigated whether γ-glutamyl-tripeptides including γ-Glu-Cys-Gly (glutathione) and its analogs S-methylglutathione and S-propylglutathione, or dipeptides including γ-Glu-Ala and γ-Glu-Cys are positive allosteric modulators of Ca(2+)(o)-dependent Ca(2+)(i) mobilization and PTH secretion from normal human parathyroid cells as well as Ca(2+)(o)-dependent suppression of intracellular cAMP levels in calcium-sensing receptor (CaR)-expressing HEK-293 cells. In addition, we compared the effects of the potent γ-glutamyl peptide S-methylglutathione, and the amino acid L-Phe on HEK-293 cells that stably expressed either the wild-type CaR or the double mutant T145A/S170T, which exhibits selectively impaired responses to L-amino acids. We find that γ-glutamyl peptides are potent positive allosteric modulators of the CaR that promote Ca(2+)(o)-dependent Ca(2+)(i) mobilization, suppress intracellular cAMP levels and inhibit PTH secretion from normal human parathyroid cells. Furthermore, we find that the double mutant T145A/S170T exhibits markedly impaired Ca(2+)(i) mobilization and cAMP suppression responses to S-methylglutathione as well as L-Phe indicating that γ-glutamyl peptides and L-amino acids activate the CaR via a common mechanism.
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Affiliation(s)
- Geoffrey K Broadhead
- School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
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6
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Chopra M, Yao Y, Blake TJ, Hampson DR, Johnson EC. The Neuroactive Peptide N-Acetylaspartylglutamate Is Not an Agonist at the Metabotropic Glutamate Receptor Subtype 3 of Metabotropic Glutamate Receptor. J Pharmacol Exp Ther 2009; 330:212-9. [DOI: 10.1124/jpet.109.152553] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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7
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Borrelli KW, Cossins B, Guallar V. Exploring hierarchical refinement techniques for induced fit docking with protein and ligand flexibility. J Comput Chem 2009; 31:1224-35. [DOI: 10.1002/jcc.21409] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Extracellular calcium-sensing receptors in fishes. Comp Biochem Physiol A Mol Integr Physiol 2008; 149:225-45. [DOI: 10.1016/j.cbpa.2008.01.037] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 01/23/2008] [Accepted: 01/23/2008] [Indexed: 11/19/2022]
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9
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Evidence for the presence of GPRC6A receptors in rat mesenteric arteries. Cell Calcium 2008; 44:210-9. [PMID: 18221783 DOI: 10.1016/j.ceca.2007.11.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 10/10/2007] [Accepted: 11/24/2007] [Indexed: 11/21/2022]
Abstract
In this study, the presence of GPRC6A receptors in rat mesenteric artery was investigated. In artery homogenates, GPRC6A mRNA was detected and Western blotting showed the presence of GPRC6A protein. Immunohistochemical studies revealed GPRC6A in both endothelial cells and myocytes. In whole vessel segments, the GPRC6A activators, 300 microM l-ornithine and 100 microM Al(3+), induced endothelium-dependent myocyte hyperpolarizations sensitive to 10 microM TRAM-34, a blocker of intermediate conductance, Ca(2+)-sensitive K(+) channels (IK(Ca)). Activation of IK(Ca) with calindol (300 nM; a positive allosteric Ca(2+)-sensing receptor - CaR - modulator) was inhibited by 500 nM ouabain (inhibition of rat type 2 and type 3 Na(+)/K(+)-ATPases) but unaffected by 30 microM Ba(2+) (blockade of inwardly rectifying K(+) channels). Neither l-ornithine nor Al(3+) activated CaRs heterologously expressed in CHO or HEK293 cells. In the presence of 300 microM l-ornithine or 100 microM Al(3+), myocyte hyperpolarizations to calindol were potentiated whereas this potentiation and hyperpolarizations to l-ornithine were lost following incubation with an anti-GPRC6A antibody. It is concluded that GPRC6A receptors are present on mesenteric artery endothelial cells and myocytes and that their activation selectively opens IK(Ca) channels. This triggers a ouabain-sensitive myocyte hyperpolarization suggesting a close functional relationship between GPRC6A, the IK(Ca) channel and type 2 and/or type 3 Na(+)/K(+)-ATPases.
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10
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Oike H, Nagai T, Furuyama A, Okada S, Aihara Y, Ishimaru Y, Marui T, Matsumoto I, Misaka T, Abe K. Characterization of ligands for fish taste receptors. J Neurosci 2007; 27:5584-92. [PMID: 17522303 PMCID: PMC6672760 DOI: 10.1523/jneurosci.0651-07.2007] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent progress in the molecular biology of taste reception has revealed that in mammals, the heteromeric receptors T1R1/3 and T1R2/3 respond to amino acids and sweeteners, respectively, whereas T2Rs are receptors for bitter tastants. Similar taste receptors have also been characterized in fish, but their ligands have not been identified yet. In the present study, we conducted a series of experiments to identify the fish taste receptor ligands. Facial nerve recordings in zebrafish (Danio rerio) demonstrated that the fish perceived amino acids and even denatonium, which is a representative of aversive bitter compounds for mammals and Drosophila. Calcium imaging analysis of T1Rs in zebrafish and medaka fish (Oryzias latipes) using an HEK293T heterologous expression system revealed that both T1R1/3 and a series of T1R2/3 responded to amino acids but not to sugars. A triple-labeling, in situ hybridization analysis demonstrated that cells expressing T1R1/3 and T1R2/3s exist in PLCbeta2-expressing taste bud cells of medaka fish. Functional analysis using T2Rs showed that zfT2R5 and mfT2R1 responded to denatonium. Behavior observations confirmed that zebrafish prefer amino acids and avoid denatonium. These results suggest that, although there may be some fish-specific way of discriminating ligands, vertebrates could have a conserved gustatory mechanism by which T1Rs and T2Rs respond to attractive and aversive tastants, respectively.
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Affiliation(s)
- Hideaki Oike
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Toshitada Nagai
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Akira Furuyama
- Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Tomita-machi, Koriyama, Fukushima 963-8611, Japan
| | - Shinji Okada
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Yoshiko Aihara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Yoshiro Ishimaru
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Takayuki Marui
- Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Tomita-machi, Koriyama, Fukushima 963-8611, Japan
| | - Ichiro Matsumoto
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Takumi Misaka
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
| | - Keiko Abe
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan, and
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11
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Conigrave AD, Hampson DR. Broad-spectrum L-amino acid sensing by class 3 G-protein-coupled receptors. Trends Endocrinol Metab 2006; 17:398-407. [PMID: 17085057 DOI: 10.1016/j.tem.2006.10.012] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 10/04/2006] [Accepted: 10/24/2006] [Indexed: 01/24/2023]
Abstract
The sensing of nutrients is essential to the control of growth and metabolism. Although the sensing mechanisms responsible for the detection and coordination of metabolic responses to some nutrients, most notably glucose, are well understood, the molecular basis of amino acid sensing by cells and tissues is only now emerging. In this article, we consider evidence that some members of G-protein-coupled receptor class 3 are broad-spectrum amino acid sensors that couple changes in extracellular amino acid levels to the activation of intracellular signaling pathways. In particular, we consider both the molecular basis of specific and broad-spectrum amino acid sensing by different members of class 3 and the physiological significance of broad spectrum amino acid sensing by the extracellular calcium-sensing receptor, heterodimeric taste receptors and the recently "deorphanized" receptor GPRC6A and its goldfish homolog, the 5.24 chemoreceptor.
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Affiliation(s)
- Arthur D Conigrave
- School of Molecular and Microbial Biosciences, University of Sydney, NSW 2006, Australia.
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12
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Kuang D, Yao Y, MacLean D, Wang M, Hampson DR, Chang BSW. Ancestral reconstruction of the ligand-binding pocket of Family C G protein-coupled receptors. Proc Natl Acad Sci U S A 2006; 103:14050-5. [PMID: 16966606 PMCID: PMC1563994 DOI: 10.1073/pnas.0604717103] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The metabotropic glutamate receptors (mGluRs) within the Family C subclass of G protein-coupled receptors are crucial modulators of synaptic transmission. However, their closest relatives include a diverse group of sensory receptors whose biological functions are not associated with neurotransmission, raising the question of the evolutionary origin of amino acid-binding Family C receptors. A common feature of most, if not all, functional Family C receptors is the presence of an amino acid-binding site localized within the large extracellular Venus flytrap domain. Here, we used maximum likelihood methods to infer the ancestral state of key residues in the amino acid-binding pocket of a primordial Family C receptor. These residues were reconstructed in the background of the fish 5.24 chemosensory receptor, a broad-spectrum amino acid-activated receptor. Unlike the WT 5.24 receptor, which was not activated by mGluR agonists and displayed low sensitivity toward l-glutamate, the reconstructed ancestral receptor possessed a pharmacological profile characterized by high affinity for both l-glutamate and selective Group I mGluR agonists. This pharmacological phenotype could be largely recapitulated by mutating only two residues in the 5.24 receptor-binding pocket. Our results suggest that this primordial Family C receptor may have arisen early in metazoan evolution and that it already was preadapted as a glutamate receptor for its later use at excitatory synapses in glutamate-mediated neurotransmission.
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Affiliation(s)
| | - Yi Yao
- Departments of Pharmaceutical Sciences
| | | | | | - David R. Hampson
- Departments of Pharmaceutical Sciences
- Pharmacology
- To whom correspondence should be addressed. E-mail:
| | - Belinda S. W. Chang
- Ecology and Evolutionary Biology, and
- Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3M2
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13
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Christiansen B, Wellendorph P, Bräuner-Osborne H. Activity of L-alpha-amino acids at the promiscuous goldfish odorant receptor 5.24. Eur J Pharmacol 2006; 536:98-101. [PMID: 16546162 DOI: 10.1016/j.ejphar.2006.02.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2006] [Accepted: 02/10/2006] [Indexed: 10/24/2022]
Abstract
The goldfish odorant receptor 5.24 is a member of family C of G protein-coupled receptors and is closely related to the human receptor GPRC6A. Receptor 5.24 has previously been shown to have binding affinity for L-alpha-amino acids, especially the basic amino acids arginine and lysine. Here we report the agonist activities of the 20 proteinogenic L-alpha-amino acids, and L-ornithine and L-citrulline, measured in an intracellular calcium release assay in mammalian tsA cells. The results show that receptor 5.24 is broadly activated by 19 of the tested L-alpha-amino acids and displays a preference for basic amino acids.
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Affiliation(s)
- Bolette Christiansen
- Department of Medicinal Chemistry, Danish University of Pharmaceutical Sciences, 2 Universitetsparken, DK-2100 Copenhagen, Denmark
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14
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Wang M, Yao Y, Kuang D, Hampson DR. Activation of family C G-protein-coupled receptors by the tripeptide glutathione. J Biol Chem 2006; 281:8864-70. [PMID: 16455645 DOI: 10.1074/jbc.m512865200] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Family C G-protein-coupled receptors include the metabotropic glutamate receptors, the gamma-aminobutyric acid, type B (GABAB) receptor, the calcium-sensing receptor (CaSR), which participates in the regulation of calcium homeostasis in the body, and a diverse group of sensory receptors that encompass the amino acid-activated fish 5.24 chemosensory receptor, the mammalian T1R taste receptors, and the V2R pheromone receptors. A common feature of Family C receptors is the presence of an amino acid binding site. In this study, a preliminary in silico analysis of the size and shape of the amino acid binding pocket in selected Family C receptors suggested that some members of this family could accommodate larger ligands such as peptides. Subsequent screening and docking experiments identified GSH as a potential ligand or co-ligand at the fish 5.24 receptor and the rat CaSR. These in silico predictions were confirmed using an [3H]GSH radioligand binding assay and a fluorescence-based functional assay performed on wild-type and chimeric receptors. Glutathione was shown to act as an orthosteric agonist at the 5.24 receptor and as a potent enhancer of calcium-induced activation of the CaSR. Within the mammalian receptors, this effect was specific to the CaSR because GSH neither directly activated nor potentiated other Family C receptors including GPRC6A (the putative mammalian homolog of the fish 5.24 receptor), the metabotropic glutamate receptors, or the GABAB receptor. Our findings reveal a potential new role for GSH and suggest that this peptide may act as an endogenous modulator of the CaSR in the parathyroid gland where this receptor is known to control the release of parathyroid hormone, and in other tissues such as the brain and gastrointestinal tract where the role of the calcium receptor appears to subserve other, as yet unknown, physiological functions.
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Affiliation(s)
- Minghua Wang
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario M5S 2S2, Canada
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