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Channuwong P, Speight V, Yuan Y, Yao S, Yoshimura M, Bauermann FV, Ranjan A, Adisakwattana S, Cheng H. Hyperglycemia from Diabetes Potentiates Uncarboxylated Osteocalcin-Stimulated Insulin Secretion in Rat INS-1 Pancreatic β-Cells. Nutrients 2024; 16:2384. [PMID: 39125265 PMCID: PMC11313777 DOI: 10.3390/nu16152384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 07/16/2024] [Accepted: 07/20/2024] [Indexed: 08/12/2024] Open
Abstract
Uncarboxylated osteocalcin (ucOC) is a hormone secreted by osteoblasts that strengthens bone during mineralization and is a biomarker for ongoing bone formation. It also regulates glucose homeostasis by stimulating insulin secretion from pancreatic β-cells. However, its effect on β-cells under hyperglycemic diabetic conditions is unclear. The objective of this study was to investigate ucOC's effect on insulin secretion in β-cells maintained under high glucose conditions. We hypothesized that hyperglycemia potentiates insulin secretion in response to ucOC stimulation. Using INS-1 cells, we performed insulin secretion experiments, intracellular calcium recordings, and RT-qPCR to determine ucOC's effect on glucose-stimulated insulin secretion (GSIS)-related genes. The results reveal that ucOC significantly increased insulin secretion under hyperglycemic conditions compared to lower glucose levels. High glucose conditions also potentiated the effect of ucOC on calcium signals, which enhanced insulin secretion. The increase in intracellular calcium was due to an influx from the extracellular space via voltage-dependent calcium channels (VDCCs). Interestingly, the treatment of cells with NPS-2143, a GPRC6A blocker, failed to abolish the calcium signals. Uncarboxylated osteocalcin upregulated the expression of GSIS-related genes under high glucose conditions (450 mg/dL) compared to cells under standard culture conditions (200 mg/dL). In conclusion, hyperglycemia potentiates ucOC-induced insulin secretion in β-cells by opening VDCCs and upregulating GSIS genes. These findings provide a better understanding of ucOC's mechanism in the diabetic state and could lead to alternative treatments to stimulate insulin secretion.
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Affiliation(s)
- Pilailak Channuwong
- Center of Excellence in Phytochemical and Functional Food for Clinical Nutrition, Department of Nutrition and Dietetics, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Victoria Speight
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Yuanying Yuan
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Shaomian Yao
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Masami Yoshimura
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Fernando V. Bauermann
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Ashish Ranjan
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sirichai Adisakwattana
- Center of Excellence in Phytochemical and Functional Food for Clinical Nutrition, Department of Nutrition and Dietetics, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Henrique Cheng
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
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2
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Extracellular Ca2+ aggravates IgE-induced allergic reaction in mast cells through GPRC6A, a novel family C G-protein-coupled receptor. Life Sci 2022; 311:121013. [DOI: 10.1016/j.lfs.2022.121013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/17/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022]
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3
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Development of a red fluorescent protein-based cGMP indicator applicable for live-cell imaging. Commun Biol 2022; 5:833. [PMID: 36064581 PMCID: PMC9445041 DOI: 10.1038/s42003-022-03790-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 08/02/2022] [Indexed: 11/08/2022] Open
Abstract
Cyclic guanosine 3', 5'-monophosphate (cGMP) is a second messenger that regulates a variety of physiological processes. Here, we develop a red fluorescent protein-based cGMP indicator, "Red cGull". The fluorescence intensity of Red cGull increase more than sixfold in response to cGMP. The features of this indicator include an EC50 of 0.33 μM for cGMP, an excitation and emission peak at 567 nm and 591 nm, respectively. Live-cell imaging analysis reveal the utility of Red cGull for dual-colour imaging and its ability to be used in conjunction with optogenetics tools. Using enteroendocrine cell lines, Red cGull detects an increase in cGMP following the application of L-arginine. An increase in intracellular cGMP is found to be inhibited by Ca2+, and L-arginine-mediated hormone secretion is not potentiated. We propose that Red cGull will facilitate future research in cell signalling in relation to cGMP and its interplay with other signalling molecules.
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4
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Mizuta H, Kumamoto N, Ugawa S, Yamamoto T. Additive Effects of L-Ornithine on Preferences to Basic Taste Solutions in Mice. Nutrients 2021; 13:3749. [PMID: 34836006 PMCID: PMC8623908 DOI: 10.3390/nu13113749] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/15/2021] [Accepted: 10/22/2021] [Indexed: 11/16/2022] Open
Abstract
In addition to the taste receptors corresponding to the six basic taste qualities-sweet, salty, sour, bitter, umami, and fatty-another type of taste receptor, calcium-sensing receptor (CaSR), is found in taste-bud cells. CaSR is called the 'kokumi' receptor because its agonists increase sweet, salty and umami tastes to induce 'koku', a Japanese word meaning the enhancement of flavor characters such as thickness, mouthfulness, and continuity. Koku is an important factor for enhancing food palatability. However, it is not well known whether other kokumi-receptors and substances exist. Here, we show that ornithine (L-ornithine but not D-ornithine) at low concentrations that do not elicit a taste of its own, enhances preferences to sweet, salty, umami, and fat taste solutions in mice. Increased preference to monosodium glutamate (MSG) was the most dominant effect. Antagonists of G-protein-coupled receptor family C group 6 subtype A (GPRC6A) abolished the additive effect of ornithine on MSG solutions. The additive effects of ornithine on taste stimuli are thought to occur in the oral cavity, and are not considered post-oral events because ornithine's effects were confirmed in a brief-exposure test. Moreover, the additive effects of ornithine and the action of the antagonist were verified in electrophysiological taste nerve responses. Immunohistochemical analysis implied that GPRC6A was expressed in subsets of type II and type III taste cells of mouse circumvallate papillae. These results are in good agreement with those reported for taste modulation involving CaSR and its agonists. The present study suggests that ornithine is a kokumi substance and GPRC6A is a newly identified kokumi receptor.
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Affiliation(s)
- Haruno Mizuta
- Department of Nutrition, Faculty of Health Sciences, Kio University, 4-2-4 Umami-naka, Koryo, Kitakatsuragi, Nara 635-0832, Japan;
| | - Natsuko Kumamoto
- Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan; (N.K.); (S.U.)
| | - Shinya Ugawa
- Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan; (N.K.); (S.U.)
| | - Takashi Yamamoto
- Department of Nutrition, Faculty of Health Sciences, Kio University, 4-2-4 Umami-naka, Koryo, Kitakatsuragi, Nara 635-0832, Japan;
- Health Science Research Center, Kio University, 4-2-4 Umami-naka, Koryo, Kitakatsuragi, Nara 635-0832, Japan
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5
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Romagnoli C, Sharma P, Zonefrati R, Palmini G, Lucattelli E, Ward DT, Ellinger I, Innocenti M, Brandi ML. Study of the Expression and Function of Calcium-Sensing Receptor in Human Skeletal Muscle. Int J Mol Sci 2021; 22:ijms22147282. [PMID: 34298895 PMCID: PMC8304165 DOI: 10.3390/ijms22147282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 01/20/2023] Open
Abstract
Skeletal muscle has an outstanding capacity for regeneration in response to injuries, but there are disorders in which this process is seriously impaired, such as sarcopenia. Pharmacological treatments to restore muscle trophism are not available, therefore, the identification of suitable therapeutic targets that could be useful for the treatment of skeletal reduced myogenesis is highly desirable. In this in vitro study, we explored the expression and function of the calcium-sensing receptor (CaSR) in human skeletal muscle tissues and their derived satellite cells. The results obtained from analyses with various techniques of gene and protein CaSR expression and of its secondary messengers in response to calcium (Ca2+) and CaSR drugs have demonstrated that this receptor is not present in human skeletal muscle tissues, neither in the established satellite cells, nor during in vitro myogenic differentiation. Taken together, our data suggest that, although CaSR is a very important drug target in physiology and pathology, this receptor probably does not have any physiological role in skeletal muscle in normal conditions.
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Affiliation(s)
- Cecilia Romagnoli
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (C.R.); (P.S.); (R.Z.); (G.P.)
| | - Preeti Sharma
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (C.R.); (P.S.); (R.Z.); (G.P.)
| | - Roberto Zonefrati
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (C.R.); (P.S.); (R.Z.); (G.P.)
- Fondazione Italiana Ricerca sulla Malattie dell’Osso (FIRMO Onlus), 50141 Florence, Italy
| | - Gaia Palmini
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (C.R.); (P.S.); (R.Z.); (G.P.)
| | - Elena Lucattelli
- Plastic and Reconstructive Microsurgery, Careggi University Hospital, 50139 Florence, Italy; (E.L.); (M.I.)
| | - Donald T. Ward
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, UK;
| | - Isabella Ellinger
- Institute for Pathophysiology and Allergy Research, Medical University of Vienna, 1090 Vienna, Austria;
| | - Marco Innocenti
- Plastic and Reconstructive Microsurgery, Careggi University Hospital, 50139 Florence, Italy; (E.L.); (M.I.)
| | - Maria Luisa Brandi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (C.R.); (P.S.); (R.Z.); (G.P.)
- Fondazione Italiana Ricerca sulla Malattie dell’Osso (FIRMO Onlus), 50141 Florence, Italy
- Correspondence:
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Modvig IM, Kuhre RE, Jepsen SL, Xu SFS, Engelstoft MS, Egerod KL, Schwartz TW, Ørskov C, Rosenkilde MM, Holst JJ. Amino acids differ in their capacity to stimulate GLP-1 release from the perfused rat small intestine and stimulate secretion by different sensing mechanisms. Am J Physiol Endocrinol Metab 2021; 320:E874-E885. [PMID: 33645250 DOI: 10.1152/ajpendo.00026.2021] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The aim of this study was to explore individual amino acid-stimulated GLP-1 responses and the underlying stimulatory mechanisms, as well as to identify the amino acid-sensing receptors involved in amino acid-stimulated GLP-1 release. Experiments were primarily based on isolated perfused rat small intestines, which have intact epithelial polarization allowing discrimination between luminal and basolateral mechanisms as well as quantitative studies of intestinal absorption and hormone secretion. Expression analysis of amino acid sensors on isolated murine GLP-1 secreting L-cells was assessed by qPCR. We found that l-valine powerfully stimulated GLP-1 secretion but only from the luminal side (2.9-fold increase). When administered from the vascular side, l-arginine and the aromatic amino acids stimulated GLP-1 secretion equally (2.6- to 2.9-fold increases). Expression analysis revealed that Casr expression was enriched in murine GLP-1 secreting L-cells, whereas Gpr35, Gprc6a, Gpr142, Gpr93 (Lpar5), and the umami taste receptor subunits Tas1r3 and Tas1r1 were not. Consistently, activation of GPR35, GPR93, GPR142, and the umami taste receptor with specific agonists or allosteric modulators did not increase GLP-1 secretion (P > 0.05 for all experiments), whereas vascular inhibition of CaSR reduced GLP-1 secretion in response to luminal infusion of mixed amino acids. In conclusion, amino acids differ in their capacity to stimulate GLP-1 secretion. Some amino acids stimulated secretion only from the intestinal lumen, whereas other amino acids exclusively stimulated secretion from the vascular side, indicating that amino acid-stimulated GLP-1 secretion involves both apical and basolateral (postabsorptive) sensing mechanisms. Sensing of absorbed amino acids involves CaSR activation as vascular inhibition of CaSR markedly diminished amino acid stimulated GLP-1 release.NEW & NOTEWORTHY Using isolated perfused rat small intestines, we show that amino acids differ in their mechanisms and capacity of stimulating GLP-1 release. Furthermore, we demonstrate that sensing by GPR142, GPR35, GPR93, and the umami taste receptor (Tas1R1/Tas1R3) are not involved in amino acid stimulated GLP-1 release. In contrast to previous studies, this experimental model allows discrimination between the luminal and the vascular side of the intestine, which is essential when studying mechanisms of amino acid-stimulated GLP-1 secretion.
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MESH Headings
- Amino Acids/pharmacology
- Animals
- Glucagon-Like Peptide 1/metabolism
- Intestine, Small/drug effects
- Intestine, Small/metabolism
- Intestine, Small/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Perfusion
- Rats
- Rats, Wistar
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Lysophosphatidic Acid/agonists
- Receptors, Lysophosphatidic Acid/metabolism
- Secretory Pathway/drug effects
- Signal Transduction/drug effects
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Affiliation(s)
- Ida Marie Modvig
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rune Ehrenreich Kuhre
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sara Lind Jepsen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stella Feng Sheng Xu
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maja Storm Engelstoft
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristoffer Lihme Egerod
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thue Walther Schwartz
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette Marie Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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7
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Wang H, Li J, Xu Z, Wu F, Zhang H, Yang C, Chen J, Ding B, Sui X, Guo Z, Li Y, Dai Z. Undercarboxylated osteocalcin inhibits the early differentiation of osteoclast mediated by Gprc6a. PeerJ 2021; 9:e10898. [PMID: 33717684 PMCID: PMC7934677 DOI: 10.7717/peerj.10898] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 01/13/2021] [Indexed: 11/20/2022] Open
Abstract
Osteocalcin (OCN) was the most abundant noncollagen protein and considered as an endocrine factor. However, the functions of Undercarboxylated osteocalcin (ucOCN) on osteoclast and bone resorption are not well understood. In the present study, preosteoclast RAW264.7 cells and bone marrow mononuclear cells (BMMs) were treated with ucOCN purified from prokaryotic bacteria. Our results showed that ucOCN attenuated the proliferation of RAW264.7 cells with a concentration dependant manner by MTS assay. Scrape wounding assay revealed the decreased motility of RAW264.7 cells after ucOCN treatment. RT-qPCR results manifested the inhibitory effects of ucOCN on the expression of osteoclastic marker genes in RAW264.7 cells during inducing differentiation of RANKL. It was also observed that ucOCN inhibited the formation of multinucleated cells from RAW264.7 cells and BMMs detected by TRAP staining. The number and area of bone resorb pits were also decreased after treatment with ucOCN during their osteoclast induction by toluidine blue staining. The formation and integrity of the osteoclast actin ring were impaired by ucOCN by immunofluorescent staining. Time dependant treatment of ucOCN during osteoclastic induction demonstrated the inhibitory effects mainly occurred at the early stage of osteoclastogenesis. Signaling analysis of luciferase activity of the CRE or SRE reporter and ERK1/2 phosphorylation showed the selective inhibitor or siRNA of Gprc6a (a presumptive ucOCN receptor) could attenuate the promotion of ucOCN on CRE-luciferase activity. Taken together, we provided the first evidence that ucOCN had negative effects on the early differentiation and bone resorption of osteoclasts via Gprc6a.
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Affiliation(s)
- Hailong Wang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Jinqiao Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China.,Space Engineering University, Beijing, China
| | - Zihan Xu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Feng Wu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Hongyu Zhang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Chao Yang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Jian Chen
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China.,Department of Orthopaedics, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Bai Ding
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Xiukun Sui
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Zhifeng Guo
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Yinghui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Zhongquan Dai
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
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8
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Jørgensen CV, Bräuner‐Osborne H. Pharmacology and physiological function of the orphan GPRC6A receptor. Basic Clin Pharmacol Toxicol 2020; 126 Suppl 6:77-87. [DOI: 10.1111/bcpt.13397] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Christinna V. Jørgensen
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Hans Bräuner‐Osborne
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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9
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Qaradakhi T, Gadanec LK, Tacey AB, Hare DL, Buxton BF, Apostolopoulos V, Levinger I, Zulli A. The Effect of Recombinant Undercarboxylated Osteocalcin on Endothelial Dysfunction. Calcif Tissue Int 2019; 105:546-556. [PMID: 31485687 DOI: 10.1007/s00223-019-00600-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 08/19/2019] [Indexed: 01/05/2023]
Abstract
Low circulating levels of undercarboxylated osteocalcin (ucOC) is associated with a higher risk of cardiovascular disease, yet whether ucOC has a direct effect on endothelium-dependent vasorelaxation, or in proximity to its postulated receptor, the class CG protein-coupled receptor (GPCR6A), in blood vessels remains unclear. Immunohistochemistry and proximity ligation assays were used to localize the presence of ucOC and GPRC6A and to determine the physical proximity (< 40 nm) in radial artery segments collected from patients undergoing coronary artery bypass surgery (n = 6) which exhibited calcification (determined by Von Kossa) and aorta from New Zealand white rabbits exhibiting atherosclerotic plaques. Endothelium-dependent vasorelaxation was assessed using cumulative doses of acetylcholine in vitro on abdominal aorta of rabbits fed a normal chow diet (n = 10) and a 4-week atherogenic diet (n = 9) pre-incubated with ucOC (10 ng/mL) or vehicle. Both ucOC and GPRC6A were localized in human and rabbit diseased-blood vessels. Proximity ligation assay staining demonstrated physical proximity of ucOC with GPRC6A only within plaques in rabbit arteries and the endothelium layer of rabbit arterioles. Endothelium-dependent vasorelaxation was impaired in atherogenic abdominal aorta compared to healthy aorta and ucOC attenuated this impairment. ucOC attenuated impaired endothelium-dependent vasorelaxation in rabbit abdominal aorta following an atherogenic diet, however, this effect may be independent of GPRC6A. It is important that future studies determine the underlying cellular mechanisms by which ucOC effects blood vessels as well as whether it can be used as a therapeutic agent against the progression of atherosclerosis.
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Affiliation(s)
- Tawar Qaradakhi
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia.
| | - Laura K Gadanec
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
| | - Alexander B Tacey
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, St Albans, VIC, 3021, Australia
| | - David L Hare
- Department of Cardiology, Austin Health, University of Melbourne, Heidelberg, VIC, 3084, Australia
| | - Brian F Buxton
- University of Melbourne, Consultant in Cardiac Surgery, Melbourne, VIC, Australia
| | - Vasso Apostolopoulos
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
| | - Itamar Levinger
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, St Albans, VIC, 3021, Australia
| | - Anthony Zulli
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
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10
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Gerbino A, Colella M. The Different Facets of Extracellular Calcium Sensors: Old and New Concepts in Calcium-Sensing Receptor Signalling and Pharmacology. Int J Mol Sci 2018; 19:E999. [PMID: 29584660 PMCID: PMC5979557 DOI: 10.3390/ijms19040999] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 03/23/2018] [Accepted: 03/25/2018] [Indexed: 12/14/2022] Open
Abstract
The current interest of the scientific community for research in the field of calcium sensing in general and on the calcium-sensing Receptor (CaR) in particular is demonstrated by the still increasing number of papers published on this topic. The extracellular calcium-sensing receptor is the best-known G-protein-coupled receptor (GPCR) able to sense external Ca2+ changes. Widely recognized as a fundamental player in systemic Ca2+ homeostasis, the CaR is ubiquitously expressed in the human body where it activates multiple signalling pathways. In this review, old and new notions regarding the mechanisms by which extracellular Ca2+ microdomains are created and the tools available to measure them are analyzed. After a survey of the main signalling pathways triggered by the CaR, a special attention is reserved for the emerging concepts regarding CaR function in the heart, CaR trafficking and pharmacology. Finally, an overview on other Ca2+ sensors is provided.
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Affiliation(s)
- Andrea Gerbino
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
| | - Matilde Colella
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
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11
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Li Z, Zeppa JJ, Hancock MA, McCormick JK, Doherty TM, Hendy GN, Madrenas J. Staphylococcal Superantigens Use LAMA2 as a Coreceptor To Activate T Cells. THE JOURNAL OF IMMUNOLOGY 2018; 200:1471-1479. [PMID: 29335257 DOI: 10.4049/jimmunol.1701212] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/15/2017] [Indexed: 01/26/2023]
Abstract
Canonical Ag-dependent TCR signaling relies on activation of the src-family tyrosine kinase LCK. However, staphylococcal superantigens can trigger TCR signaling by activating an alternative pathway that is independent of LCK and utilizes a Gα11-containing G protein-coupled receptor (GPCR) leading to PLCβ activation. The molecules linking the superantigen to GPCR signaling are unknown. Using the ligand-receptor capture technology LRC-TriCEPS, we identified LAMA2, the α2 subunit of the extracellular matrix protein laminin, as the coreceptor for staphylococcal superantigens. Complementary binding assays (ELISA, pull-downs, and surface plasmon resonance) provided direct evidence of the interaction between staphylococcal enterotoxin E and LAMA2. Through its G4 domain, LAMA2 mediated the LCK-independent T cell activation by these toxins. Such a coreceptor role of LAMA2 involved a GPCR of the calcium-sensing receptor type because the selective antagonist NPS 2143 inhibited superantigen-induced T cell activation in vitro and delayed the effects of toxic shock syndrome in vivo. Collectively, our data identify LAMA2 as a target of antagonists of staphylococcal superantigens to treat toxic shock syndrome.
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Affiliation(s)
- Zhigang Li
- Microbiome and Disease Tolerance Centre, Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Joseph J Zeppa
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 5C1, Canada
| | - Mark A Hancock
- Surface Plasmon Resonance-Mass Spectrometry Facility, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - John K McCormick
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 5C1, Canada.,Lawson Health Research Institute, London, Ontario N6A 5C1, Canada
| | - Terence M Doherty
- Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles Medical Center, Torrance, CA 90277; and
| | - Geoffrey N Hendy
- Metabolic Disorders and Complications, Research Institute of the McGill University Health Centre, and Departments of Medicine, Physiology, and Human Genetics, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Joaquín Madrenas
- Microbiome and Disease Tolerance Centre, Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada; .,Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles Medical Center, Torrance, CA 90277; and
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12
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Vass M, Kooistra AJ, Verhoeven S, Gloriam D, de Esch IJP, de Graaf C. A Structural Framework for GPCR Chemogenomics: What's In a Residue Number? Methods Mol Biol 2018; 1705:73-113. [PMID: 29188559 DOI: 10.1007/978-1-4939-7465-8_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The recent surge of crystal structures of G protein-coupled receptors (GPCRs), as well as comprehensive collections of sequence, structural, ligand bioactivity, and mutation data, has enabled the development of integrated chemogenomics workflows for this important target family. This chapter will focus on cross-family and cross-class studies of GPCRs that have pinpointed the need for, and the implementation of, a generic numbering scheme for referring to specific structural elements of GPCRs. Sequence- and structure-based numbering schemes for different receptor classes will be introduced and the remaining caveats will be discussed. The use of these numbering schemes has facilitated many chemogenomics studies such as consensus binding site definition, binding site comparison, ligand repurposing (e.g. for orphan receptors), sequence-based pharmacophore generation for homology modeling or virtual screening, and class-wide chemogenomics studies of GPCRs.
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Affiliation(s)
- Márton Vass
- Department of Medicinal Chemistry, Amsterdam Institute for Molecules Medicines and Systems, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HV, Amsterdam, The Netherlands
| | - Albert J Kooistra
- Department of Medicinal Chemistry, Amsterdam Institute for Molecules Medicines and Systems, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HV, Amsterdam, The Netherlands
- Centre for Molecular and Biomolecular Informatics (CMBI), Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Stefan Verhoeven
- Netherlands eScience Center, 1098 XG, Amsterdam, The Netherlands
| | - David Gloriam
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Iwan J P de Esch
- Department of Medicinal Chemistry, Amsterdam Institute for Molecules Medicines and Systems, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HV, Amsterdam, The Netherlands
| | - Chris de Graaf
- Department of Medicinal Chemistry, Amsterdam Institute for Molecules Medicines and Systems, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HV, Amsterdam, The Netherlands.
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13
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Ho YY, Nakato J, Mizushige T, Kanamoto R, Tanida M, Akiduki S, Ohinata K. l-Ornithine stimulates growth hormone release in a manner dependent on the ghrelin system. Food Funct 2017; 8:2110-2114. [PMID: 28513740 DOI: 10.1039/c7fo00309a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We found that intraduodenal administration of l-ornithine (l-Orn) stimulates growth hormone (GH) secretion in Wistar rats, and then investigated its mechanism. GH-releasing activity after intraduodenal administration of l-Orn was blocked by [d-Lys3]-GHRP-6, an antagonist of the ghrelin receptor; however, l-Orn (100 μM) has no affinity for the ghrelin receptor, suggesting that the GH-releasing activity of l-Orn is mediated via ghrelin release and activation of the ghrelin receptor. Intraduodenally administered l-Orn increased ghrelin mRNA expression in the duodenum but not in the stomach or hypothalamus. In addition, l-Orn-induced GH-releasing activity was inhibited by propranolol, an antagonist of β-adrenergic receptor, which is known to be coupled to ghrelin release. In conclusion, intraduodenally administered l-Orn stimulates GH secretion through the sympathetic nervous and ghrelin systems.
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Affiliation(s)
- Yee Yin Ho
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
| | - Junya Nakato
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
| | - Takafumi Mizushige
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan. and Research Unit for Physiological Chemistry, C-PIER, Kyoto University, Kyoto 606-8501, Japan
| | - Ryuhei Kanamoto
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
| | - Mamoru Tanida
- Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-kita, Kusatsu, Shiga 525-8577, Japan and Department of Physiology II Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
| | - Saori Akiduki
- Healthcare Products Development Center, Kyowa Hakko Bio Co., Ltd, Tsukuba, Ibaraki 305-0841, Japan
| | - Kousaku Ohinata
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
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14
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Leach K, Gregory KJ. Molecular insights into allosteric modulation of Class C G protein-coupled receptors. Pharmacol Res 2017; 116:105-118. [DOI: 10.1016/j.phrs.2016.12.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 11/18/2016] [Accepted: 12/07/2016] [Indexed: 12/23/2022]
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15
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Jørgensen S, Have CT, Underwood CR, Johansen LD, Wellendorph P, Gjesing AP, Jørgensen CV, Quan S, Rui G, Inoue A, Linneberg A, Grarup N, Jun W, Pedersen O, Hansen T, Bräuner-Osborne H. Genetic Variations in the Human G Protein-coupled Receptor Class C, Group 6, Member A (GPRC6A) Control Cell Surface Expression and Function. J Biol Chem 2016; 292:1524-1534. [PMID: 27986810 DOI: 10.1074/jbc.m116.756577] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/14/2016] [Indexed: 12/30/2022] Open
Abstract
GPRC6A is a G protein-coupled receptor activated by l-amino acids, which, based on analyses of knock-out mice, has been suggested to have physiological functions in metabolism and testicular function. The human ortholog is, however, mostly retained intracellularly in contrast to the cell surface-expressed murine and goldfish orthologs. The latter orthologs are Gq-coupled and lead to intracellular accumulation of inositol phosphates and calcium release. In the present study we cloned the bonobo chimpanzee GPRC6A receptor, which is 99% identical to the human receptor, and show that it is cell surface-expressed and functional. By analyses of chimeric human/mouse and human/bonobo receptors, bonobo receptor mutants, and the single nucleotide polymorphism database at NCBI, we identify an insertion/deletion variation in the third intracellular loop responsible for the intracellular retention and lack of function of the human ortholog. Genetic analyses of the 1000 genome database and the Inter99 cohort of 6,000 Danes establish the distribution of genotypes among ethnic groups, showing that the cell surface-expressed and functional variant is much more prevalent in the African population than in European and Asian populations and that this variant is partly linked with a stop codon early in the receptor sequence (rs6907580, amino acid position 57). In conclusion, our data solve a more than decade-old question of why the cloned human GPRC6A receptor is not cell surface-expressed and functional and provide a genetic framework to study human phenotypic traits in large genome sequencing projects linked with physiological measurement and biomarkers.
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Affiliation(s)
- Stine Jørgensen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Christian Theil Have
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christina Rye Underwood
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Lars Dan Johansen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Petrine Wellendorph
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Anette Prior Gjesing
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christinna V Jørgensen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Shi Quan
- BGI-Shenzhen, Shenzhen 518083, China
| | - Gao Rui
- BGI-Shenzhen, Shenzhen 518083, China
| | - Asuka Inoue
- the Laboratory of Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.,the Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology, Kawaguchi, Saitama 332-0012, Japan
| | - Allan Linneberg
- the Research Centre for Prevention and Health, Capital Region of Denmark, DK-2600 Glostrup, Denmark.,the Department of Clinical Experimental Research, Rigshospitalet, DK-2100 Copenhagen, Denmark, and.,the Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Niels Grarup
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Wang Jun
- BGI-Shenzhen, Shenzhen 518083, China
| | - Oluf Pedersen
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Torben Hansen
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark,
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16
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Greenberg HZE, Jahan KS, Shi J, Vanessa Ho WS, Albert AP. The calcilytics Calhex-231 and NPS 2143 and the calcimimetic Calindol reduce vascular reactivity via inhibition of voltage-gated Ca 2+ channels. Eur J Pharmacol 2016; 791:659-668. [PMID: 27725162 PMCID: PMC5127511 DOI: 10.1016/j.ejphar.2016.10.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 12/11/2022]
Abstract
The present study investigates the effect of commonly used negative and positive allosteric modulators of the calcium-sensing receptor (CaSR) on vascular reactivity. In wire myography studies, increasing [Ca2+]o from 1mM to 6mM induced concentration-dependent relaxations of methoxamine-induced pre-contracted rabbit mesenteric arteries, with 6mM [Ca2+]o producing almost complete relaxation. [Ca2+]o-induced relaxations were attenuated in the presence of the calcilytics Calhex-231 and NPS 2143, and abolished by the removal of the endothelium. In addition to their calcilytic effects, Calhex-231 and NPS 2143 also produced concentration-dependent inhibitions of methoxamine- or KCl-induced precontracted tone, which were unaffected by removal of the endothelium and unopposed in the presence of the calcimimetic Calindol. In vessels with depleted Ca2+ stores, contractions mediated by Ca2+ influx via voltage-gated Ca2+ channels (VGCCs) were inhibited by Calhex231. In freshly isolated single rabbit mesenteric artery smooth muscle cells, Calhex-231 and NPS 2143 inhibited whole-cell VGCC currents. Application of Calindol also inhibited methoxamine- and KCl-induced pre-contracted tone, and inhibited whole-cell VGCC currents. In conclusion, in addition to their CaSR-mediated actions in the vasculature, Calhex-231, NPS 2143 and Calindol reduce vascular contractility via direct inhibition of VGCCs.
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Affiliation(s)
- Harry Z E Greenberg
- Vascular Biology Research Centre, Institute of Cardiovascu lar & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
| | - Kazi S Jahan
- Vascular Biology Research Centre, Institute of Cardiovascu lar & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Jian Shi
- Vascular Biology Research Centre, Institute of Cardiovascu lar & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - W-S Vanessa Ho
- Vascular Biology Research Centre, Institute of Cardiovascu lar & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Anthony P Albert
- Vascular Biology Research Centre, Institute of Cardiovascu lar & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
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17
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Pi M, Kapoor K, Ye R, Nishimoto SK, Smith JC, Baudry J, Quarles LD. Evidence for Osteocalcin Binding and Activation of GPRC6A in β-Cells. Endocrinology 2016; 157:1866-80. [PMID: 27007074 PMCID: PMC4870875 DOI: 10.1210/en.2015-2010] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The possibility that G protein-coupled receptor family C member A (GPRC6A) is the osteocalcin (Ocn)-sensing G protein-coupled receptor that directly regulates pancreatic β-cell functions is controversial. In the current study, we found that Ocn and an Ocn-derived C-terminal hexapeptide directly activate GPRC6A-dependent ERK signaling in vitro. Computational models probe the structural basis of Ocn binding to GPRC6A and predict that the C-terminal hexapeptide docks to the extracellular side of the transmembrane domain of GPRC6A. Consistent with the modeling, mutations in the computationally identified binding pocket of GPRC6A reduced Ocn and C-terminal hexapeptide activation of this receptor. In addition, selective deletion of Gprc6a in β-cells (Gprc6a(β)(-cell-cko)) by crossing Gprc6a(flox/flox) mice with Ins2-Cre mice resulted in reduced pancreatic weight, islet number, insulin protein content, and insulin message expression. Both islet size and β-cell proliferation were reduced in Gprc6a(β)(-cell-cko) compared with control mice. Gprc6a(β)(-cell-cko) exhibited abnormal glucose tolerance, but normal insulin sensitivity. Islets isolated from Gprc6a(β)(-cell-cko) mice showed reduced insulin simulation index in response to Ocn. These data establish the structural basis for Ocn direct activation of GPRC6A and confirm a role for GPRC6A in regulating β-cell proliferation and insulin secretion.
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Affiliation(s)
- Min Pi
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Karan Kapoor
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Ruisong Ye
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Satoru Kenneth Nishimoto
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Jeremy C Smith
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Jerome Baudry
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Leigh Darryl Quarles
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
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18
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Design and synthesis of calindol derivatives as potent and selective calcium sensing receptor agonists. Bioorg Med Chem 2016; 24:554-69. [DOI: 10.1016/j.bmc.2015.12.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 11/13/2015] [Accepted: 12/10/2015] [Indexed: 01/04/2023]
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19
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Rueda P, Harley E, Lu Y, Stewart GD, Fabb S, Diepenhorst N, Cremers B, Rouillon MH, Wehrle I, Geant A, Lamarche G, Leach K, Charman WN, Christopoulos A, Summers RJ, Sexton PM, Langmead CJ. Murine GPRC6A Mediates Cellular Responses to L-Amino Acids, but Not Osteocalcin Variants. PLoS One 2016; 11:e0146846. [PMID: 26785252 PMCID: PMC4718634 DOI: 10.1371/journal.pone.0146846] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/21/2015] [Indexed: 12/13/2022] Open
Abstract
Phenotyping of Gprc6a KO mice has shown that this promiscuous class C G protein coupled receptor is variously involved in regulation of metabolism, inflammation and endocrine function. Such effects are described as mediated by extracellular calcium, L-amino acids, the bone-derived peptide osteocalcin (OCN) and the male hormone testosterone, introducing the concept of a bone-energy-metabolism-reproduction functional crosstalk mediated by GPRC6A. However, whilst the calcium and L-amino acid-sensing properties of GPRC6A are well established, verification of activity of osteocalcin at both human and mouse GPRC6A in vitro has proven somewhat elusive. This study characterises the in vitro pharmacology of mouse GPRC6A in response to its putative ligands in both recombinant and endogenous GPRC6A-expressing cells. Using cell signalling, and glucagon-like peptide (GLP)-1 and insulin release assays, our results confirm that basic L-amino acids act as agonists of the murine GPRC6A receptor in both recombinant cells and immortalised entero-endocrine and pancreatic β-cells. In contrast, our studies do not support a role for OCN as a direct ligand for mouse GPRC6A, suggesting that the reported in vivo effects of OCN that require GPRC6A may be indirect, rather than via direct activation of the receptor.
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Affiliation(s)
- Patricia Rueda
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | | | - Yao Lu
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Gregory D. Stewart
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Stewart Fabb
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Natalie Diepenhorst
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | | | | | | | - Anne Geant
- Institut de Recherches Servier, Suresnes, France
| | | | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - William N. Charman
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Roger J. Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Patrick M. Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Christopher J. Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- * E-mail:
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20
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GPRC6A mediates Alum-induced Nlrp3 inflammasome activation but limits Th2 type antibody responses. Sci Rep 2015; 5:16719. [PMID: 26602597 PMCID: PMC4658484 DOI: 10.1038/srep16719] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/19/2015] [Indexed: 12/22/2022] Open
Abstract
Alum adjuvanticity is still an unknown mechanism despite the frequent use as vaccine
adjuvant in humans. Here we show that Alum-induced inflammasome activation in
vitro and in vivo is mediated by the G protein-coupled receptor
GPRC6A. The Alum-induced humoral response in vivo was independent of the
inflammasome because Nlrp3−/− and
ASC−/− mice responded normally to Alum and blockade of IL-1
had no effect on antibody production. In contrast, Alum adjuvanticity was increased
in GPRC6A−/− mice resulting in increased antibody responses
and increased Th2 cytokine concentrations compared to wildtype mice. In vitro
activation of GPRC6A−/− splenic B cells also induced
increased IgG1 concentrations compared to wildtype B cells. For the first time, we
show GPRC6A expression in B cells, contributing to the direct effects of Alum on
those cells. B cell produced immunostimulatory IL-10 is elevated in
GPRC6A−/− B cells in vitro and in vivo. Our
results demonstrate a dual role of GPRC6A in Alum adjuvanticity. GPCR6A activation
by Alum leads to the initiation of innate inflammatory responses whereas it is an
important signal for the limitation of adaptive immune responses induced by Alum,
partially explained by B cell IL-10.
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21
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Chemosensory signalling pathways involved in sensing of amino acids by the ghrelin cell. Sci Rep 2015; 5:15725. [PMID: 26510380 PMCID: PMC4625164 DOI: 10.1038/srep15725] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 10/01/2015] [Indexed: 01/06/2023] Open
Abstract
Taste receptors on enteroendocrine cells sense nutrients and transmit signals that control gut hormone release. This study aimed to investigate the amino acid (AA) sensing mechanisms of the ghrelin cell in a gastric ghrelinoma cell line, tissue segments and mice. Peptone and specific classes of amino acids stimulate ghrelin secretion in the ghrelinoma cell line. Sensing of L-Phe occurs via the CaSR, monosodium glutamate via the TAS1R1-TAS1R3 while L-Ala and peptone act via 2 different amino acid taste receptors: CaSR &TAS1R1-TAS1R3 and CaSR &GPRC6A, respectively. The stimulatory effect of peptone on ghrelin release was mimicked ex vivo in gastric but not in jejunal tissue segments, where peptone inhibited ghrelin release. The latter effect could not be blocked by receptor antagonists for CCK, GLP-1 or somatostatin. In vivo, plasma ghrelin levels were reduced both upon intragastric (peptone or L-Phe) or intravenous (L-Phe) administration, indicating that AA- sensing is not polarized and is due to inhibition of ghrelin release from the stomach or duodenum respectively. In conclusion, functional AA taste receptors regulate AA-induced ghrelin release in vitro. The effects differ between stomach and jejunum but these local nutrient sensing mechanisms are overruled in vivo by indirect mechanisms inhibiting ghrelin release.
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22
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Pi M, Kapoor K, Wu Y, Ye R, Senogles SE, Nishimoto SK, Hwang DJ, Miller DD, Narayanan R, Smith JC, Baudry J, Quarles LD. Structural and Functional Evidence for Testosterone Activation of GPRC6A in Peripheral Tissues. Mol Endocrinol 2015; 29:1759-73. [PMID: 26440882 DOI: 10.1210/me.2015-1161] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
G protein-coupled receptor (GPCR) family C group 6 member A (GPRC6A) is a multiligand GPCR that is activated by cations, L-amino acids, and osteocalcin. GPRC6A plays an important role in the regulation of testosterone (T) production and energy metabolism in mice. T has rapid, transcription-independent (nongenomic) effects that are mediated by a putative GPCR. We previously found that T can activate GPRC6A in vitro, but the possibility that T is a ligand for GPRC6A remains controversial. Here, we demonstrate direct T binding to GPRC6A and construct computational structural models of GPRC6A that are used to identify potential binding poses of T. Mutations of the predicted binding site residues were experimentally found to block T activation of GPRC6A, in agreement with the modeling. Using Gpr6ca(-/-) mice, we confirmed that loss of GPRC6A resulted in loss of T rapid signaling responses and elucidated several biological functions regulated by GPRC6A-dependent T rapid signaling, including T stimulation of insulin secretion in pancreatic islets and enzyme expression involved in the biosynthesis of T in Leydig cells. Finally, we identified a stereo-specific effect of an R-isomer of a selective androgen receptor modulator that is predicted to bind to and shown to activate GPRC6A but not androgen receptor. Together, our data show that GPRC6A directly mediates the rapid signaling response to T and uncovers previously unrecognized endocrine networks.
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Affiliation(s)
- Min Pi
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Karan Kapoor
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Yunpeng Wu
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Ruisong Ye
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Susan E Senogles
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Satoru K Nishimoto
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Dong-Jin Hwang
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Duane D Miller
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Ramesh Narayanan
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Jeremy C Smith
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - Jerome Baudry
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
| | - L Darryl Quarles
- Departments of Medicine (M.P., Y.W., R.Y., R.N., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.E.S., S.K.N.), and Pharmaceutical Sciences (D.-J.H., D.D.M.), College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S., J.B.), University of Tennessee, Knoxville, Tennessee 37996
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Arginine-induced insulin secretion in endoplasmic reticulum. Biochem Biophys Res Commun 2015; 466:717-22. [PMID: 26348775 DOI: 10.1016/j.bbrc.2015.09.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 09/03/2015] [Indexed: 01/31/2023]
Abstract
Arginine, a semi-essential amino acid, is known as one of the most strongest insulin secretagogues in a glucose-dependent manner, but major mechanism is unknown. Arginine induced insulin secretion in mice as well as β cell line, NIT-1, in which more than 90% of intracellular insulin is prionsulin without arginine cultivation. Arginine administration reduced prionsulin amount in 30 s, then insulin is secreted from NIT1 cells. These data indicated that the target factor(s) for arginine-induced insulin secretion located in endoplasmic reticulum (ER). We established the screening system for identifying the arginine mimetics. Brazilian propolis, not Chinese propolis, induced insulin secretion. To identify target factor(s) of arginine induced insulin secretion, our previous study was that nanobeads technology facilitated us to purify chemical-target factors. This time we chose the other way, proinsulin associating factor purification and arginine-immobilized agarose. Three proinsulin associating factors and 5 arginine interacting factors were identified. Among theses factors, Calnexin (CNX) was the only one factor, which belonged to both groups, suggesting that CNX might play a key role in arginine-induced insulin secretion in ER.
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Mace OJ, Tehan B, Marshall F. Pharmacology and physiology of gastrointestinal enteroendocrine cells. Pharmacol Res Perspect 2015. [PMID: 26213627 PMCID: PMC4506687 DOI: 10.1002/prp2.155] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gastrointestinal (GI) polypeptides are secreted from enteroendocrine cells (EECs). Recent technical advances and the identification of endogenous and synthetic ligands have enabled exploration of the pharmacology and physiology of EECs. Enteroendocrine signaling pathways stimulating hormone secretion involve multiple nutrient transporters and G protein-coupled receptors (GPCRs), which are activated simultaneously under prevailing nutrient conditions in the intestine following a meal. The majority of studies investigate hormone secretion from EECs in response to single ligands and although the mechanisms behind how individual signaling pathways generate a hormonal output have been well characterized, our understanding of how these signaling pathways converge to generate a single hormone secretory response is still in its infancy. However, a picture is beginning to emerge of how nutrients and full, partial, or allosteric GPCR ligands differentially regulate the enteroendocrine system and its interaction with the enteric and central nervous system. So far, activation of multiple pathways underlies drug discovery efforts to harness the therapeutic potential of the enteroendocrine system to mimic the phenotypic changes observed in patients who have undergone Roux-en-Y gastric surgery. Typically obese patients exhibit ∼30% weight loss and greater than 80% of obese diabetics show remission of diabetes. Targeting combinations of enteroendocrine signaling pathways that work synergistically may manifest with significant, differentiated EEC secretory efficacy. Furthermore, allosteric modulators with their increased selectivity, self-limiting activity, and structural novelty may translate into more promising enteroendocrine drugs. Together with the potential to bias enteroendocrine GPCR signaling and/or to activate multiple divergent signaling pathways highlights the considerable range of therapeutic possibilities available. Here, we review the pharmacology and physiology of the EEC system.
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Affiliation(s)
- O J Mace
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - B Tehan
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - F Marshall
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
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25
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The role of the calcium-sensing receptor in disorders of abnormal calcium handling and cardiovascular disease. Curr Opin Nephrol Hypertens 2015; 23:494-501. [PMID: 24992569 DOI: 10.1097/mnh.0000000000000042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW The calcium-sensing receptor (CaSR) has a central role in parathyroid gland function. Genetic alterations in CaSR are well known to cause inherited forms of abnormal calcium homeostasis. This review focuses on studies investigating the role of CaSR in common disorders of abnormal calcium handling and in cardiovascular calcification. RECENT FINDINGS Genetic population studies tested the association of common allelic CASR variants with serum and urine calcium levels, kidney stone disease, primary hyperparathyroidism and bone mineral density. The results of these association studies suggested either minor or no effects of CASR variants in these phenotypes. Decreased expression of CaSR was associated with the etiology of cardiovascular calcification in individuals with advanced chronic kidney disease. SUMMARY Ionized calcium plays a central role in the physiology of many organ systems and disease states, but the roles of CaSR other than as illustrated by Mendelian forms of CaSR dysfunction remain unclear. The contributions of CaSR to bone mineral homeostasis, vascular calcification and other forms of cardiovascular disease need further investigation.
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Abstract
PURPOSE OF REVIEW Variations in extracellular calcium level have a large impact on kidney function. Most of the effects seen are attributed to the calcium-sensing receptor (CaSR), a widely expressed G-protein-coupled cell surface protein with an important function in bone mineral homeostasis. The purpose of this review is to recapitulate the novel functional aspects of CaSR. RECENT FINDINGS Results from mouse models demonstrate important functions for CaSR in various tissues. In the kidney, the main role of CaSR is the regulation of calcium reabsorption in the thick ascending limb, independently of its role on parathyroid hormone secretion. CaSR modulates claudin 14, the gatekeeper of paracellular ion transport in the thick ascending limb that is associated with urinary calcium excretion. One intracellular signaling pathway by which CaSR alters tight junction permeability is the calcineurin-NFAT1c-microRNA-claudin14 axis. SUMMARY The main function of CaSR in the kidney is the regulation of calcium excretion in the thick ascending limb, independently of parathyroid hormone. CaSR modulates paracellular cation transport by altering expression of the tight junction protein claudin 14. Still more work is needed to fully understand all functions of CaSR in the kidney. Alternative pathways of calcium 'sensing' in the kidney need to be investigated.
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Affiliation(s)
- Hakan R Toka
- aDivision of Nephrology, Beth Israel Deaconess Medical Center bDivision of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Clemmensen C, Smajilovic S, Wellendorph P, Bräuner-Osborne H. The GPCR, class C, group 6, subtype A (GPRC6A) receptor: from cloning to physiological function. Br J Pharmacol 2014; 171:1129-41. [PMID: 24032653 DOI: 10.1111/bph.12365] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/25/2013] [Accepted: 08/26/2013] [Indexed: 12/16/2022] Open
Abstract
GPRC6A (GPCR, class C, group 6, subtype A) is a class C GPCR that has been cloned from human, mouse and rat. Several groups have shown that the receptor is activated by a range of basic and small aliphatic L-α-amino acids of which L-arginine, L-lysine and L-ornithine are the most potent compounds with EC50 values in the mid-micromolar range. In addition, several groups have shown that the receptor is either directly activated or positively modulated by divalent cations such as Ca(2+) albeit in concentrations above 5 mM, which is above the physiological concentration in most tissues. More recently, the peptide osteocalcin and the steroid testosterone have also been suggested to be endogenous GPRC6A agonists. The receptor is widely expressed in all three species which, along with the omnipresence of the amino acids and divalent cation ligands, suggest that the receptor could be involved in a broad range of physiological functions. So far, this has mainly been addressed by analyses of genetically modified mice where the GPRC6A receptor has been ablated. Although there has been some discrepancies among results reported from different groups, there is increasing evidence that the receptor is involved in regulation of inflammation, metabolism and endocrine functions. GPRC6A could thus be an interesting target for new drugs in these therapeutic areas.
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Affiliation(s)
- C Clemmensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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28
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Ko E, Choi H, Kim B, Kim M, Park KN, Bae IH, Sung YK, Lee TR, Shin DW, Bae YS. Testosterone stimulates Duox1 activity through GPRC6A in skin keratinocytes. J Biol Chem 2014; 289:28835-45. [PMID: 25164816 DOI: 10.1074/jbc.m114.583450] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Testosterone is an endocrine hormone with functions in reproductive organs, anabolic events, and skin homeostasis. We report here that GPRC6A serves as a sensor and mediator of the rapid action of testosterone in epidermal keratinocytes. The silencing of GPRC6A inhibited testosterone-induced intracellular calcium ([Ca(2+)]i) mobilization and H2O2 generation. These results indicated that a testosterone-GPRC6A complex is required for activation of Gq protein, IP3 generation, and [Ca(2+)]i mobilization, leading to Duox1 activation. H2O2 generation by testosterone stimulated the apoptosis of keratinocytes through the activation of caspase-3. The application of testosterone into three-dimensional skin equivalents increased the apoptosis of keratinocytes between the granular and stratified corneum layers. These results support an understanding of the molecular mechanism of testosterone-dependent apoptosis in which testosterone stimulates H2O2 generation through the activation of Duox1.
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Affiliation(s)
- Eunbi Ko
- From the Department of Life Science and GT5 program, Ewha Womans University
| | - Hyun Choi
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, 446-729 and
| | - Borim Kim
- From the Department of Life Science and GT5 program, Ewha Womans University
| | - Minsun Kim
- From the Department of Life Science and GT5 program, Ewha Womans University
| | - Kkot-Nara Park
- From the Department of Life Science and GT5 program, Ewha Womans University
| | - Il-Hong Bae
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, 446-729 and
| | - Young Kwan Sung
- the Department of Immunology, School of Medicine, Kyungpook National University, Daegu 700-422, Republic of Korea
| | - Tae Ryong Lee
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, 446-729 and
| | - Dong Wook Shin
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, 446-729 and
| | - Yun Soo Bae
- From the Department of Life Science and GT5 program, Ewha Womans University,
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Deregulation of bone forming cells in bone diseases and anabolic effects of strontium-containing agents and biomaterials. BIOMED RESEARCH INTERNATIONAL 2014; 2014:814057. [PMID: 24800251 PMCID: PMC3988913 DOI: 10.1155/2014/814057] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 02/20/2014] [Accepted: 03/03/2014] [Indexed: 11/30/2022]
Abstract
Age-related bone loss and osteoporosis are associated with bone remodeling changes that are featured with decreased trabecular and periosteal bone formation relative to bone resorption. Current anticatabolic therapies focusing on the inhibition of bone resorption may not be sufficient in the prevention or reversal of age-related bone deterioration and there is a big need in promoting osteoblastogenesis and bone formation. Enhanced understanding of the network formed by key signaling pathways and molecules regulating bone forming cells in health and diseases has therefore become highly significant. The successful development of agonist/antagonist of the PTH and Wnt signaling pathways are profits of the understanding of these key pathways. As the core component of an approved antiosteoporosis agent, strontium takes its effect on osteoblasts at multilevel through multiple pathways, representing a good example in revealing and exploring anabolic mechanisms. The recognition of strontium effects on bone has led to its expected application in a variety of biomaterial scaffolds used in tissue engineering strategies aiming at bone repairing and regeneration. While summarizing the recent progress in these respects, this review also proposes the new approaches such as systems biology in order to reveal new insights in the pathology of osteoporosis as well as possible discovery of new therapies.
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Diakogiannaki E, Pais R, Tolhurst G, Parker HE, Horscroft J, Rauscher B, Zietek T, Daniel H, Gribble FM, Reimann F. Oligopeptides stimulate glucagon-like peptide-1 secretion in mice through proton-coupled uptake and the calcium-sensing receptor. Diabetologia 2013; 56:2688-96. [PMID: 24045836 PMCID: PMC3825574 DOI: 10.1007/s00125-013-3037-3] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/01/2013] [Indexed: 01/25/2023]
Abstract
AIMS/HYPOTHESIS Ingested protein is a well-recognised stimulus for glucagon-like peptide-1 (GLP-1) release from intestinal L cells. This study aimed to characterise the molecular mechanisms employed by L cells to detect oligopeptides. METHODS GLP-1 secretion from murine primary colonic cultures and Ca(2+) dynamics in L cells were monitored in response to peptones and dipeptides. L cells were identified and purified based on their cell-specific expression of the fluorescent protein Venus, using GLU-Venus transgenic mice. Pharmacological tools and knockout mice were used to characterise candidate sensory pathways identified by expression analysis. RESULTS GLP-1 secretion was triggered by peptones and di-/tripeptides, including the non-metabolisable glycine-sarcosine (Gly-Sar). Two sensory mechanisms involving peptide transporter-1 (PEPT1) and the calcium-sensing receptor (CaSR) were distinguishable. Responses to Gly-Sar (10 mmol/l) were abolished in the absence of extracellular Ca(2+) or by the L-type calcium-channel blocker nifedipine (10 μmol/l) and were PEPT1-dependent, as demonstrated by their sensitivity to pH and 4-aminomethylbenzoic acid and the finding of impaired responses in tissue from Pept1 (also known as Slc15a1) knockout mice. Peptone (5 mg/ml)-stimulated Ca(2+) responses were insensitive to nifedipine but were blocked by antagonists of CaSR. Peptone-stimulated GLP-1 secretion was not impaired in mice lacking the putative peptide-responsive receptor lysophosphatidic acid receptor 5 (LPAR5; also known as GPR92/93). CONCLUSIONS/INTERPRETATION Oligopeptides stimulate GLP-1 secretion through PEPT1-dependent electrogenic uptake and activation of CaSR. Both pathways are highly expressed in native L cells, and likely contribute to the ability of ingested protein to elevate plasma GLP-1 levels. Targeting nutrient-sensing pathways in L cells could be used to mobilise endogenous GLP-1 stores in humans, and could mimic some of the metabolic benefits of bariatric surgery.
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Affiliation(s)
- Eleftheria Diakogiannaki
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
| | - Ramona Pais
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
| | - Gwen Tolhurst
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
| | - Helen E. Parker
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
| | - James Horscroft
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
| | - Beate Rauscher
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, München, Germany
| | - Tamara Zietek
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, München, Germany
| | - Hannelore Daniel
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, München, Germany
| | - Fiona M. Gribble
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
| | - Frank Reimann
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke’s Hospital, Box 139, Hills Road, Cambridge, CB2 0XY UK
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31
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Fann DYW, Lee SY, Manzanero S, Chunduri P, Sobey CG, Arumugam TV. Pathogenesis of acute stroke and the role of inflammasomes. Ageing Res Rev 2013; 12:941-66. [PMID: 24103368 DOI: 10.1016/j.arr.2013.09.004] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 09/12/2013] [Accepted: 09/19/2013] [Indexed: 12/20/2022]
Abstract
Inflammation is an innate immune response to infection or tissue damage that is designed to limit harm to the host, but contributes significantly to ischemic brain injury following stroke. The inflammatory response is initiated by the detection of acute damage via extracellular and intracellular pattern recognition receptors, which respond to conserved microbial structures, termed pathogen-associated molecular patterns or host-derived danger signals termed damage-associated molecular patterns. Multi-protein complexes known as inflammasomes (e.g. containing NLRP1, NLRP2, NLRP3, NLRP6, NLRP7, NLRP12, NLRC4, AIM2 and/or Pyrin), then process these signals to trigger an effector response. Briefly, signaling through NLRP1 and NLRP3 inflammasomes produces cleaved caspase-1, which cleaves both pro-IL-1β and pro-IL-18 into their biologically active mature pro-inflammatory cytokines that are released into the extracellular environment. This review will describe the molecular structure, cellular signaling pathways and current evidence for inflammasome activation following cerebral ischemia, and the potential for future treatments for stroke that may involve targeting inflammasome formation or its products in the ischemic brain.
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32
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Johansson H, Cailly T, Rojas Bie Thomsen A, Bräuner-Osborne H, Sejer Pedersen D. Synthesis of the calcilytic ligand NPS 2143. Beilstein J Org Chem 2013; 9:1383-7. [PMID: 23946832 PMCID: PMC3740522 DOI: 10.3762/bjoc.9.154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/11/2013] [Indexed: 01/15/2023] Open
Abstract
(R)-3 (NPS 2143) is a negative allosteric modulator of the human calcium-sensing receptor (CaSR) and as such represents an important pharmacological tool compound for studying the CaSR. Herein, we disclose for the first time a complete experimental description, detailed characterisation and assessment of enantiomeric purity for (R)-3. An efficient, reproducible and scalable synthesis of (R)-3 that requires a minimum of chromatographic purification steps is presented. (R)-3 was obtained in excellent optical purity (er > 99:1) as demonstrated by chiral HPLC and the pharmacological profile for (R)-3 is in full accordance with that reported in the literature.
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Affiliation(s)
- Henrik Johansson
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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33
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Wauson EM, Lorente-Rodríguez A, Cobb MH. Minireview: Nutrient sensing by G protein-coupled receptors. Mol Endocrinol 2013; 27:1188-97. [PMID: 23820899 DOI: 10.1210/me.2013-1100] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are membrane proteins that recognize molecules in the extracellular milieu and transmit signals inside cells to regulate their behaviors. Ligands for many GPCRs are hormones or neurotransmitters that direct coordinated, stereotyped adaptive responses. Ligands for other GPCRs provide information to cells about the extracellular environment. Such information facilitates context-specific decision making that may be cell autonomous. Among ligands that are important for cellular decisions are amino acids, required for continued protein synthesis, as metabolic starting materials and energy sources. Amino acids are detected by a number of class C GPCRs. One cluster of amino acid-sensing class C GPCRs includes umami and sweet taste receptors, GPRC6A, and the calcium-sensing receptor. We have recently found that the umami taste receptor heterodimer T1R1/T1R3 is a sensor of amino acid availability that regulates the activity of the mammalian target of rapamycin. This review focuses on an array of findings on sensing amino acids and sweet molecules outside of neurons by this cluster of class C GPCRs and some of the physiologic processes regulated by them.
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Affiliation(s)
- Eric M Wauson
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9041, USA
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34
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Extracellular Ca2+ is a danger signal activating the NLRP3 inflammasome through G protein-coupled calcium sensing receptors. Nat Commun 2013; 3:1329. [PMID: 23271661 PMCID: PMC3535422 DOI: 10.1038/ncomms2339] [Citation(s) in RCA: 343] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 11/27/2012] [Indexed: 12/21/2022] Open
Abstract
Activation of the NLRP3 inflammasome enables monocytes and macrophages to release high levels of interleukin-1β during inflammatory responses. Concentrations of extracellular calcium can increase at sites of infection, inflammation or cell activation. Here we show that increased extracellular calcium activates the NLRP3 inflammasome via stimulation of G protein-coupled calcium sensing receptors. Activation is mediated by signalling through the calcium-sensing receptor and GPRC6A via the phosphatidyl inositol/Ca2+ pathway. The resulting increase in the intracellular calcium concentration triggers inflammasome assembly and Caspase-1 activation. We identified necrotic cells as one source for excess extracellular calcium triggering this activation. In vivo, increased calcium concentrations can amplify the inflammatory response in the mouse model of carrageenan-induced footpad swelling, and this effect was inhibited in GPRC6A−/− mice. Our results demonstrate that G-protein-coupled receptors can activate the inflammasome, and indicate that increased extracellular calcium has a role as a danger signal and amplifier of inflammation. Levels of extracellular calcium can increase at sites of infection and inflammation; however, the physiological significance of this has been unclear. This work shows that extracellular calcium acts as a danger signal, triggering the NLRP3 inflammasome via two G protein-coupled receptors.
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Abstract
The calcium sensing receptor (CaSR) is expressed by subpopulations of neuronal and glial cells throughout the brain and is activated by extracellular calcium [Formula: see text] . During development, the CaSR regulates neuronal cell growth and migration as well as oligodendroglial maturation and function. Emerging evidence suggests that in nerve terminals, CaSR is implicated in synaptic plasticity and neurotransmission. In this review, we analyze the roles attributed to CaSR in regulating diverse brain functions, including central regulation of body fluid composition and blood pressure. We also discuss the potential relevance of Ca(2+)-sensing in brain by other family C G protein-coupled receptors. Finally, evidence that the CaSR contributes to the pathogenesis of various brain disorders raises the possibility that pharmacological modulators of the CaSR may have therapeutic benefit.
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Affiliation(s)
- Martial Ruat
- CNRS-UPR-3294, Laboratory of Neurobiology and Development, Institute of Neurobiology, Alfred Fessard IFR2118, Signal Transduction and Developmental Neuropharmacology Team, 1 Avenue de la Terrasse, F-91198, Gif-sur-Yvette, France.
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Kooistra AJ, Roumen L, Leurs R, de Esch IJ, de Graaf C. From Heptahelical Bundle to Hits from the Haystack. Methods Enzymol 2013; 522:279-336. [DOI: 10.1016/b978-0-12-407865-9.00015-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Oya M, Kitaguchi T, Pais R, Reimann F, Gribble F, Tsuboi T. The G protein-coupled receptor family C group 6 subtype A (GPRC6A) receptor is involved in amino acid-induced glucagon-like peptide-1 secretion from GLUTag cells. J Biol Chem 2012; 288:4513-21. [PMID: 23269670 DOI: 10.1074/jbc.m112.402677] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Although amino acids are dietary nutrients that evoke the secretion of glucagon-like peptide 1 (GLP-1) from intestinal L cells, the precise molecular mechanism(s) by which amino acids regulate GLP-1 secretion from intestinal L cells remains unknown. Here, we show that the G protein-coupled receptor (GPCR), family C group 6 subtype A (GPRC6A), is involved in amino acid-induced GLP-1 secretion from the intestinal L cell line GLUTag. Application of l-ornithine caused an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in GLUTag cells. Application of a GPRC6A receptor antagonist, a phospholipase C inhibitor, or an IP(3) receptor antagonist significantly suppressed the l-ornithine-induced [Ca(2+)](i) increase. We found that the increase in [Ca(2+)](i) stimulated by l-ornithine correlated with GLP-1 secretion and that l-ornithine stimulation increased exocytosis in a dose-dependent manner. Furthermore, depletion of endogenous GPRC6A by a specific small interfering RNA (siRNA) inhibited the l-ornithine-induced [Ca(2+)](i) increase and GLP-1 secretion. Taken together, these findings suggest that the GPRC6A receptor functions as an amino acid sensor in GLUTag cells that promotes GLP-1 secretion.
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Affiliation(s)
- Manami Oya
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
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Tonack S, Tang C, Offermanns S. Endogenous metabolites as ligands for G protein-coupled receptors modulating risk factors for metabolic and cardiovascular disease. Am J Physiol Heart Circ Physiol 2012; 304:H501-13. [PMID: 23241321 DOI: 10.1152/ajpheart.00641.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
During the last decade, several G protein-coupled receptors activated by endogenous metabolites have been described. These receptors respond to fatty acids, mono- and disaccharides, amino acids, or various intermediates and products of metabolism, including ketone bodies, lactate, succinate, or bile acids. Receptors of endogenous metabolites are expressed in taste cells, the gastrointestinal tract, adipose tissue, endocrine glands, immune cells, or the kidney and are therefore in a position to sense food intake in the gastrointestinal tract or to link metabolite levels to the appropriate responses of metabolic organs. Some of the receptors appear to provide a link between metabolic and neuronal or immune functions. Given that many of these metabolic processes are dysregulated under pathological conditions, including diabetes, dyslipidemia, and obesity, receptors of endogenous metabolites have also been recognized as potential drug targets to prevent and/or treat metabolic and cardiovascular diseases. This review describes G protein-coupled receptors activated by endogenous metabolites and summarizes their physiological, pathophysiological, and potential pharmacological roles.
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Affiliation(s)
- Sarah Tonack
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
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Pi M, Quarles LD. Multiligand specificity and wide tissue expression of GPRC6A reveals new endocrine networks. Endocrinology 2012; 153:2062-9. [PMID: 22374969 PMCID: PMC3339644 DOI: 10.1210/en.2011-2117] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 01/30/2012] [Indexed: 01/29/2023]
Abstract
Emerging evidence supports the hypothesis that the skeleton is an endocrine organ that regulates energy metabolism through the release of the osteoblast-derived hormone, osteocalcin (Ocn). This bone-pancreas endocrine network is controversial because important gaps remain to be filled in our knowledge of the physiological effects of Ocn in multiple organs and the complex alterations in other hormonal networks induced by Ocn administration. A key step toward understanding the integrative regulation of energy metabolism by bone is the identification of GPCR family C group 6 member A (GPRC6A) as the Ocn receptor. GPRC6A is an amino acid-sensing G protein-coupled receptor highly expressed in β-cells and is activated by recombinant Ocn in vitro and in vivo but that is widely expressed in tissues other than the pancreas and is capable of sensing multiple structurally unrelated ligands, including l-amino acids, cations, and anabolic steroids in addition to Ocn. The broad expression and multiligand specificity of GPRC6A is identifying both systemic and paracrine regulation of seemingly disparate biological processes, ranging from energy metabolism, sexual reproduction, hypothalamic-pituitary function, bone formation, and prostate cancer. Consistent with the existence of more complex endocrine networks, ablation of GPRC6A in Gprc6a(-/-) mice results in complex metabolic abnormalities, including obesity, glucose intolerance, hepatic steatosis, insulin resistance, hyperphosphatemia, osteopenia, plus several hormonal abnormalities, including decreased circulating testosterone, IGF-I, and insulin and increased estradiol, LH, GH, and leptin. Recombinant Ocn also regulates testosterone production by the testes and male fertility through a GPRC6A-dependent mechanism, and testosterone regulation of LH secretion is abnormal in Gprc6a(-/-) mice. Thus, GPRC6A, as the biologically relevant receptor for Ocn, defines not only a molecular mechanism for linking bone metabolism with metabolic regulation of β-cells and sexual reproduction but also as a receptor shared by testosterone and dietary factors, and it is also involved in multiple endocrine networks integrating the functions of pancreas, muscle, liver, fat, testes, bone, and the hypothalamic-pituitary axis with alterations in both environmental and endogenous ligands.
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Affiliation(s)
- Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Gloriam DE, Wellendorph P, Johansen LD, Thomsen ARB, Phonekeo K, Pedersen DS, Bräuner-Osborne H. Chemogenomic discovery of allosteric antagonists at the GPRC6A receptor. CHEMISTRY & BIOLOGY 2011; 18:1489-98. [PMID: 22118683 DOI: 10.1016/j.chembiol.2011.09.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 08/17/2011] [Accepted: 09/13/2011] [Indexed: 12/13/2022]
Abstract
GPRC6A is a Family C G protein-coupled receptor recently discovered and deorphanized by our group. This study integrates chemogenomic ligand inference, homology modeling, compound synthesis, and pharmacological mechanism-of-action studies to disclose two noticeable results of methodological and pharmacological character: (1) chemogenomic lead identification through the first, to our knowledge, ligand inference between two different GPCR families, Families A and C; and (2) the discovery of the most selective GPRC6A allosteric antagonists discovered to date. The unprecedented inference of pharmacological activity across GPCR families provides proof-of-concept for in silico approaches against Family C targets based on Family A templates, greatly expanding the prospects of successful drug design and discovery. The antagonists were tested against a panel of seven Family A and C G protein-coupled receptors containing the chemogenomic binding sequence motif where some of the identified GPRC6A antagonists showed some activity. However, three compounds with at least ∼3-fold selectivity for GPRC6A were discovered, which present a significant step forward compared with the previously published GPRC6A antagonists, calindol and NPS 2143, which both display ∼30-fold selectivity for the calcium-sensing receptor compared to GPRC6A. The antagonists constitute novel research tools toward investigating the signaling mechanism of the GPRC6A receptor at the cellular level and serve as initial ligands for further optimization of potency and selectivity enabling future ex vivo/in vivo pharmacological studies.
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Affiliation(s)
- David E Gloriam
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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Xiong W, Liu T, Wang Y, Chen X, Sun L, Guo N, Zheng H, Zheng L, Ruat M, Han W, Zhang CX, Zhou Z. An inhibitory effect of extracellular Ca2+ on Ca2+-dependent exocytosis. PLoS One 2011; 6:e24573. [PMID: 22028769 PMCID: PMC3196490 DOI: 10.1371/journal.pone.0024573] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 08/14/2011] [Indexed: 11/21/2022] Open
Abstract
Aim Neurotransmitter release is elicited by an elevation of intracellular Ca2+ concentration ([Ca2+]i). The action potential triggers Ca2+ influx through Ca2+ channels which causes local changes of [Ca2+]i for vesicle release. However, any direct role of extracellular Ca2+ (besides Ca2+ influx) on Ca2+-dependent exocytosis remains elusive. Here we set out to investigate this possibility on rat dorsal root ganglion (DRG) neurons and chromaffin cells, widely used models for studying vesicle exocytosis. Results Using photolysis of caged Ca2+ and caffeine-induced release of stored Ca2+, we found that extracellular Ca2+ inhibited exocytosis following moderate [Ca2+]i rises (2–3 µM). The IC50 for extracellular Ca2+ inhibition of exocytosis (ECIE) was 1.38 mM and a physiological reduction (∼30%) of extracellular Ca2+ concentration ([Ca2+]o) significantly increased the evoked exocytosis. At the single vesicle level, quantal size and release frequency were also altered by physiological [Ca2+]o. The calcimimetics Mg2+, Cd2+, G418, and neomycin all inhibited exocytosis. The extracellular Ca2+-sensing receptor (CaSR) was not involved because specific drugs and knockdown of CaSR in DRG neurons did not affect ECIE. Conclusion/Significance As an extension of the classic Ca2+ hypothesis of synaptic release, physiological levels of extracellular Ca2+ play dual roles in evoked exocytosis by providing a source of Ca2+ influx, and by directly regulating quantal size and release probability in neuronal cells.
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Affiliation(s)
- Wei Xiong
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Tao Liu
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Yeshi Wang
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Xiaowei Chen
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Lei Sun
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Ning Guo
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Hui Zheng
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Lianghong Zheng
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Martial Ruat
- CNRS, UPR9040, Institut de Neurobiologie Alfred Fessard-IFR 2118, Gif sur Yvette, France
| | - Weiping Han
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Claire Xi Zhang
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
- * E-mail: (ZZ); (CXZ)
| | - Zhuan Zhou
- State Key Laboratory of Biomembrane Engineering and Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, China
- * E-mail: (ZZ); (CXZ)
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Thakore P, Ho WSV. Vascular actions of calcimimetics: role of Ca²(+) -sensing receptors versus Ca²(+) influx through L-type Ca²(+) channels. Br J Pharmacol 2011; 162:749-62. [PMID: 20958288 DOI: 10.1111/j.1476-5381.2010.01079.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND AND PURPOSE The calcimimetic, (R)-N-(3-(3-(trifluoromethyl)phenyl)propyl)-1-(1-napthyl)ethylamine hydrochloride (cinacalcet), which activates Ca²(+) -sensing receptors (CaR) in parathyroid glands, is used to treat hyperparathyroidism. Interestingly, CaR in perivascular nerves or endothelial cells is also thought to modulate vascular tone. This study aims to characterize the vascular actions of calcimimetics. EXPERIMENTAL APPROACH In rat isolated small mesenteric arteries, the relaxant responses to the calcimimetics, cinacalcet and (R)-2-[[[1-(1-naphthyl)ethyl]amino]methyl]-1H-indole hydrochloride (calindol) were characterized, with particular emphasis on the role of CaR, endothelium, perivascular nerves, K(+) channels and Ca²(+) channels. Effects of L-ornithine, which activates a Ca(2+) -sensitive receptor related to CaR (GPRC6A), were also tested. KEY RESULTS Cinacalcet induced endothelium-independent relaxation (pEC₅₀ 5.58 ± 0.07, E(max) 97 ± 6%) that was insensitive to sensory nerve desensitization by capsaicin or blockade of large-conductance Ca²(+) -activated K(+) channels by iberiotoxin. Calindol, another calcimimetic, caused more potent relaxation (pEC₅₀ 6.10 ± 0.10, E(max) 101 ± 6%), which was attenuated by endothelial removal or capsaicin, but not iberiotoxin. The negative modulator of CaR, calhex 231 or changes in [Ca²(+) ](o) had negligible effect on relaxation to both calcimimetics. The calcimimetics relaxed vessels precontracted with high [K(+) ](o) and inhibited Ca²(+) influx in endothelium-denuded vessels stimulated by methoxamine, but not ionomycin. They also inhibited contractions to the L-type Ca²(+) channel activator, BayK8644. L-ornithine induced small relaxation alone and had no effect on the responses to calcimimetics. CONCLUSION AND IMPLICATIONS Cinacalcet and calindol are potent arterial relaxants. Under the experimental conditions used, they predominantly act by inhibiting Ca²(+) influx through L-type Ca²(+) channels into vascular smooth muscle, whereas Ca²(+) -sensitive receptors (CaR or GPRC6A) play a minor role.
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Affiliation(s)
- Pratish Thakore
- Division of Basic Medical Sciences, St George's University of London, Cranmer Terrace, London, UK
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Kiefer L, Leiris S, Dodd RH. Novel calcium sensing receptor ligands: a patent survey. Expert Opin Ther Pat 2011; 21:681-98. [PMID: 21406038 DOI: 10.1517/13543776.2011.568479] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION In the parathyroid gland, the calcium sensing receptor responds to small changes in circulating levels of Ca(2+), and consequently stimulates or inhibits the secretion of parathyroid hormone (PTH). Thus, ligands potentiating the action of calcium (calcimimetics) lead to decreased PTH secretion and can thus be useful for the treatment of hyperparathyroidism. On the other hand, ligands which antagonize the action of calcium (calcilytics) stimulate PTH secretion, favoring bone tissue regeneration. AREAS COVERED This review first discusses the rapid development of calcimimetics (only one of which has been approved for the treatment of hyperparathyroidism) followed by that of calcilytics (none of which has as yet been approved for the treatment of osteoporosis). Peer-reviewed articles generated by these patents are also surveyed. EXPERT OPINION The rapid progress in developing a clinically approved calcimimetic has not been matched by an identical success in finding an orally available calcilytic useful for the treatment of osteoporosis. However, the growing importance of osteoporosis as a debilitating disease is a stimulating factor in discovering such compounds.
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Affiliation(s)
- Lionel Kiefer
- Institut de Chimie des Substances Naturelles, UPR 2301, CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
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Roudaut H, Traiffort E, Gorojankina T, Vincent L, Faure H, Schoenfelder A, Mann A, Manetti F, Solinas A, Taddei M, Ruat M. Identification and Mechanism of Action of the Acylguanidine MRT-83, a Novel Potent Smoothened Antagonist. Mol Pharmacol 2010; 79:453-60. [DOI: 10.1124/mol.110.069708] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Kiefer L, Gorojankina T, Dauban P, Faure H, Ruat M, Dodd RH. Design and synthesis of cyclic sulfonamides and sulfamates as new calcium sensing receptor agonists. Bioorg Med Chem Lett 2010; 20:7483-7. [PMID: 21041081 DOI: 10.1016/j.bmcl.2010.10.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 10/01/2010] [Accepted: 10/02/2010] [Indexed: 11/27/2022]
Abstract
The design, synthesis and calcimimetic properties of various cyclic sulfonamides and sulfamates are described. The latter were prepared from the corresponding o-alkenylarenesulfonamides via copper- or rhodium-catalyzed intramolecular aziridination. The size of the cyclic sulfonamide rings as well as the position of the crucial (R)-naphthylethylamine substituent significantly affected calcimimetic activity. The most active compounds were the six- and seven-membered sulfonamides 30a and 31a and sulfamate 34a.
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Affiliation(s)
- Lionel Kiefer
- Institut de Chimie des Substances Naturelles, UPR 2301, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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Wellendorph P, Johansen LD, Bräuner-Osborne H. The Emerging Role of Promiscuous 7TM Receptors as Chemosensors for Food Intake. INCRETINS AND INSULIN SECRETION 2010; 84:151-84. [DOI: 10.1016/b978-0-12-381517-0.00005-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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