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Sato H, Murakami S, Horii Y, Nishimura G, Iwai R, Goto M, Takahashi N. Upacicalcet is a novel secondary hyperparathyroidism drug that targets the amino acid binding site of calcium-sensing receptor. Mol Pharmacol 2022; 102:183-195. [DOI: 10.1124/molpharm.122.000522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 07/14/2022] [Indexed: 11/22/2022] Open
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2
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Duanmu Q, Tan B, Wang J, Huang B, Li J, Kang M, Huang K, Deng Q, Yin Y. The Amino Acids Sensing and Utilization in Response to Dietary Aromatic Amino Acid Supplementation in LPS-Induced Inflammation Piglet Model. Front Nutr 2022; 8:819835. [PMID: 35111801 PMCID: PMC8801454 DOI: 10.3389/fnut.2021.819835] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 12/16/2021] [Indexed: 12/19/2022] Open
Abstract
Dietary supplementation with aromatic amino acids (AAAs) has been demonstrated to alleviate intestinal inflammation induced by lipopolysaccharide (LPS) in the piglets. But the mechanism of AAA sensing and utilization under inflammatory conditions is not well-understood. The study was conducted with 32 weanling piglets using a 2 × 2 factorial arrangement (diet and LPS challenge) in a randomized complete block design. Piglets were fed as basal diet or the basal diet supplemented with 0.16% tryptophan (Trp), 0.41% phenylalanine (Phe), and 0.22% tyrosine (Tyr) for 21 days. The results showed that LPS treatment significantly reduced the concentrations of cholecystokinin (CCK) and total protein but increased leptin concentration, the activities of alanine transaminase, and aspartate aminotransferase in serum. Dietary supplementation with AAAs significantly increased the serum concentrations of CCK, peptide YY (PYY), and total protein but decreased the blood urea nitrogen. LPS challenge reduced the ileal threonine (Thr) digestibility, as well as serum isoleucine (Ile) and Trp concentrations, but increased the serum concentrations of Phe, Thr, histidine (His), alanine (Ala), cysteine (Cys), and serine (Ser) (P < 0.05). The serum-free amino acid concentrations of His, lysine (Lys), arginine (Arg), Trp, Tyr, Cys, and the digestibilities of His, Lys, Arg, and Cys were significantly increased by feeding AAA diets (P < 0.05). Dietary AAA supplementation significantly increased the serum concentrations of Trp in LPS-challenged piglets (P < 0.05). In the jejunal mucosa, LPS increased the contents of Ala and Cys, and the mRNA expressions of solute carrier (SLC) transporters (i.e., SLC7A11, SLC16A10, SLC38A2, and SLC3A2), but decreased Lys and glutamine (Gln) contents, and SLC1A1 mRNA expression (P < 0.05). In the ileal mucosa, LPS challenge induced increasing in SLC7A11 and SLC38A2 and decreasing in SLC38A9 and SLC36A1 mRNA expressions, AAAs supplementation significantly decreased mucosal amino acid (AA) concentrations of methionine (Met), Arg, Ala, and Tyr, etc. (P < 0.05). And the interaction between AAAs supplementation and LPS challenge significantly altered the expressions of SLC36A1 and SLC38A9 mRNA (P < 0.05). Together, these findings indicated that AAAs supplementation promoted the AAs absorption and utilization in the small intestine of piglets and increased the mRNA expressions of SLC transports to meet the high demands for specific AAs in response to inflammation and immune response.
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Affiliation(s)
- Qing Duanmu
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Bie Tan
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Jing Wang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Bo Huang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Jianjun Li
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Meng Kang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Ke Huang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Qiuchun Deng
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Yulong Yin
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
- Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
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3
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The Association between Branched-Chain Amino Acids (BCAAs) and Cardiometabolic Risk Factors in Middle-Aged Caucasian Women Stratified According to Glycemic Status. Nutrients 2021; 13:nu13103307. [PMID: 34684308 PMCID: PMC8538048 DOI: 10.3390/nu13103307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/17/2021] [Accepted: 09/19/2021] [Indexed: 02/07/2023] Open
Abstract
We examined the glycemic status-stratified relationships between total serum branched-chain amino acid (BCAA) concentrations and cardiometabolic risk factors in middle-aged Caucasian women. The study included 349 women divided into 2 subgroups: a normoglycemic group (NG, n = 184) and a dysglycemic group (DG, n = 165). Blood samples, anthropometric parameters, and blood pressure were measured. HOMA-IR, albumin-corrected calcium (CCa), and fatty liver index (FLI) were calculated. BCAA concentrations were higher in the women with dysglycemia. BCAAs moderately correlated with BMI and FLI in the NG group and with BMI, FLI, total calcium (TCa), CCa, HbA1c, TG/HDL-C, and HDL-C in the DG group. After adjusting for age and BMI, correlations for TCa, CCa, HbA1c, HDL-C, and TG/HDL-C remained significant. The coexistence of increased BCAAs with dysglycemic status was associated with markedly higher concentrations of TCa, CCa, HbA1c, and TG, which were not observed in the DG women with low level of BCAAs. Multiple regression showed that TCa or CCa, age and BCAAs were significantly associated with HbA1c independently of BMI only in the DG group. We conclude that dysglycemia in particular predisposes women to a significant relationship between total BCAAs and circulating calcium and HbA1c, and that these relationships are independent of BMI and may reflect the pathophysiological calcium-dependent mechanisms connecting BCAAs with metabolic disturbances.
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Tang PK, Geddes RF, Jepson RE, Elliott J. A feline-focused review of chronic kidney disease-mineral and bone disorders - Part 1: Physiology of calcium handling. Vet J 2021; 275:105719. [PMID: 34311095 DOI: 10.1016/j.tvjl.2021.105719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 06/03/2021] [Accepted: 07/21/2021] [Indexed: 01/01/2023]
Abstract
Mineral derangements are a common consequence of chronic kidney disease (CKD). Despite the well-established role of phosphorus in the pathophysiology of CKD, the implications of calcium disturbances associated with CKD remain equivocal. Calcium plays an essential role in numerous physiological functions in the body and is a fundamental structural component of bone. An understanding of calcium metabolism is required to understand the potential adverse clinical implications and outcomes secondary to the (mal)adaptation of calcium-regulating hormones in CKD. The first part of this two-part review covers the physiology of calcium homeostasis (kidneys, intestines and bones) and details the intimate relationships between calcium-regulating hormones (parathyroid hormone, calcitriol, fibroblast growth factor 23, α-Klotho and calcitonin) and the role of the calcium-sensing receptor.
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Affiliation(s)
- Pak-Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK.
| | - Rebecca F Geddes
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, UK
| | - Rosanne E Jepson
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, UK
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK
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5
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Watkins JD, Koumanov F, Gonzalez JT. Protein- and Calcium-Mediated GLP-1 Secretion: A Narrative Review. Adv Nutr 2021; 12:2540-2552. [PMID: 34192748 PMCID: PMC8634310 DOI: 10.1093/advances/nmab078] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/31/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023] Open
Abstract
Glucagon-like peptide 1 (GLP-1) is an incretin hormone produced in the intestine that is secreted in response to nutrient exposure. GLP-1 potentiates glucose-dependent insulin secretion from the pancreatic β cells and promotes satiety. These important actions on glucose metabolism and appetite have led to widespread interest in GLP-1 receptor agonism. Typically, this involves pharmacological GLP-1 mimetics or targeted inhibition of dipeptidyl peptidase-IV, the enzyme responsible for GLP-1 degradation. However, nutritional strategies provide a widely available, cost-effective alternative to pharmacological strategies for enhancing hormone release. Recent advances in nutritional research have implicated the combined ingestion of protein and calcium with enhanced endogenous GLP-1 release, which is likely due to activation of receptors with high affinity and/or sensitivity for amino acids and calcium. Specifically targeting these receptors could enhance gut hormone secretion, thus providing a new therapeutic option. This narrative review provides an overview of the latest research on protein- and calcium-mediated GLP-1 release with an emphasis on human data, and a perspective on potential mechanisms that link potent GLP-1 release to the co-ingestion of protein and calcium. In light of these recent findings, potential future research directions are also presented.
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Affiliation(s)
- Jonathan D Watkins
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
| | - Françoise Koumanov
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
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Zakaria NF, Hamid M, Khayat ME. Amino Acid-Induced Impairment of Insulin Signaling and Involvement of G-Protein Coupling Receptor. Nutrients 2021; 13:nu13072229. [PMID: 34209599 PMCID: PMC8308393 DOI: 10.3390/nu13072229] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/18/2021] [Accepted: 06/24/2021] [Indexed: 12/12/2022] Open
Abstract
Amino acids are needed for general bodily function and well-being. Despite their importance, augmentation in their serum concentration is closely related to metabolic disorder, insulin resistance (IR), or worse, diabetes mellitus. Essential amino acids such as the branched-chain amino acids (BCAAs) have been heavily studied as a plausible biomarker or even a cause of IR. Although there is a long list of benefits, in subjects with abnormal amino acids profiles, some amino acids are correlated with a higher risk of IR. Metabolic dysfunction, upregulation of the mammalian target of the rapamycin (mTOR) pathway, the gut microbiome, 3-hydroxyisobutyrate, inflammation, and the collusion of G-protein coupled receptors (GPCRs) are among the indicators and causes of metabolic disorders generating from amino acids that contribute to IR and the onset of type 2 diabetes mellitus (T2DM). This review summarizes the current understanding of the true involvement of amino acids with IR. Additionally, the involvement of GPCRs in IR will be further discussed in this review.
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Affiliation(s)
- Nur Fatini Zakaria
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
| | - Muhajir Hamid
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
| | - Mohd Ezuan Khayat
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
- Correspondence:
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Wang W, Wu H, Xiao Q, Zhou H, Li M, Xu Q, Wang Q, Yu F, He J. Crystal structure details of Vibrio fischeri DarR and mutant DarR-M202I from LTTR family reveals their activation mechanism. Int J Biol Macromol 2021; 183:2354-2363. [PMID: 34081954 DOI: 10.1016/j.ijbiomac.2021.05.186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/05/2021] [Accepted: 05/26/2021] [Indexed: 02/02/2023]
Abstract
DarR, a novel member of the LTTR family derived from Vibrio fischeri, activates transcription in response to d-Asp and regulates the overexpression of the racD genes encoding a putative aspartate racemase, RacD. Here, the crystal structure of full-length DarR and its mutant DarR-M202I were obtained by X-ray crystallography. According to the electron density map analysis of full-length DarR, the effector binding site of DarR is occupied by 2-Morpholinoethanesulfonic acid monohydrate (MES), which could interact with amino acids in the effector binding site and stabilize the effector binding site. Furthermore, we elaborated the structure of DarR-M202I, where methionine is replaced by isoleucine resulting in overexpression of the downstream operon. By comparing DarR-MES and DarR-M202I, we found similar behavior of DarR-MES in terms of the stability of the RD active pocket and the deflection angle of the DBD. The Isothermal titration calorimetry and Gel-filtration chromatography experiments showed that only when the target DNA sequence of a particular quasi-palindromic sequence exceeds 19 bp, DarR can effectively bind to racD promoter. This study will help enhance our understanding of the mechanism in the transcriptional regulation of LTTR family transcription factors.
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Affiliation(s)
- Weiwei Wang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hai Wu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qingjie Xiao
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Huan Zhou
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Minjun Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Qin Xu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Qisheng Wang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Feng Yu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Jianhua He
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China.
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8
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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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Amin A, Frampton J, Liu Z, Franco-Becker G, Norton M, Alaa A, Li JV, Murphy KG. Differential effects of L- and D-phenylalanine on pancreatic and gastrointestinal hormone release in humans: A randomized crossover study. Diabetes Obes Metab 2021; 23:147-157. [PMID: 32991046 DOI: 10.1111/dom.14204] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/11/2020] [Accepted: 09/25/2020] [Indexed: 12/16/2022]
Abstract
AIM To investigate the effects of L-phenylalanine on gastroenteropancreatic hormone release, glucose levels, subjective appetite and energy intake in humans, and to determine whether these effects were stereoisomer-specific by comparing them with D-phenylalanine. MATERIALS AND METHODS A dose-finding, non-randomized, unblinded, crossover study was conducted during October-December 2017 at the NIHR Imperial Clinical Research Facility in five participants, in which the tolerability of escalating doses of oral L-phenylalanine was assessed (0, 3, 6 and 10 g). Also, an acute, randomized, double-blind, placebo-controlled crossover study was conducted during January-May 2018 at the NIHR Imperial Clinical Research Facility in 11 participants, in which the effects of oral 10 g L-phenylalanine relative to D-phenylalanine and placebo on gastroenteropancreatic hormone (insulin, glucagon, glucose-dependent insulinotropic polypeptide [GIP], peptide tyrosine tyrosine [PYY], glucagon-like peptide-1) and glucose concentrations, visual analogue scales for subjective appetite and energy intake at an ad libitum meal served 70 minutes postingestion, were investigated. RESULTS L-phenylalanine was well-tolerated and increased insulin and glucagon concentrations prior to meal ingestion at several time points relative to placebo and D-phenylalanine (P < .05). L-phenylalanine also increased GIP concentrations relative to D-phenylalanine (P = .0420) and placebo (P = .0249) 70 minutes following ingestion. L-phenylalanine reduced postprandial glucose area under the curve (AUC)70-150mins relative to placebo (P = .0317) but did not affect subjective appetite or energy intake (P > .05). D-phenylalanine increased postprandial PYY AUC70-150mins concentrations relative to placebo (P = .0002). CONCLUSIONS Ingestion of L-phenylalanine, but not D-phenylalanine, increases insulin, glucagon and GIP concentrations without appearing to have a marked effect on appetite.
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Affiliation(s)
- Anjali Amin
- Section of Endocrinology and Investigative Medicine, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - James Frampton
- Section for Nutrition Research, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Zhigang Liu
- Section for Nutrition Research, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Georgia Franco-Becker
- Section for Nutrition Research, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Mariana Norton
- Section of Endocrinology and Investigative Medicine, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Aos Alaa
- Section for Nutrition Research, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Jia V Li
- Section for Nutrition Research, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Kevin G Murphy
- Section of Endocrinology and Investigative Medicine, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
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10
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Comesaña S, Conde-Sieira M, Velasco C, Soengas JL, Morais S. Oral and pre-absorptive sensing of amino acids relates to hypothalamic control of food intake in rainbow trout. J Exp Biol 2020; 223:jeb221721. [PMID: 32680900 DOI: 10.1242/jeb.221721] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 07/14/2020] [Indexed: 12/28/2022]
Abstract
To assess the putative role of taste and pre-absorptive sensing of amino acids in food intake control in fish, we carried out an oral administration with l-leucine, l-valine, l-proline or l-glutamic acid in rainbow trout (Oncorhynchus mykiss). Treatment with proline significantly reduced voluntary food intake at 2 h and 3 h after oral administration, while glutamic acid showed a less pronounced satiating effect at 3 h. The mRNA expression of taste receptor subunits tas1r1, tas1r2a, tas1r2b and tas1r3 was measured in the epithelium overlying the bony basihyal of the fish (analogous to the tetrapod tongue) at 10, 20 or 30 min following treatment. No significant changes were observed, except for a tas1r down-regulation by valine at 30 min. Of the downstream taste signalling genes that were analysed in parallel, plcb2 and possibly trpm5 (non-significant trend) were down-regulated 20 min after proline and glutamic acid treatment. The signal originated in the oropharyngeal and/or gastric cavity presumably relays to the brain as changes in genes involved in the regulation of food intake occurred in hypothalamus 10-30 min after oral treatment with amino acids. In particular, proline induced changes consistent with an increased anorexigenic potential in the hypothalamus. We have therefore demonstrated, for the first time in fish, that the peripheral (pre-absorptive) detection of an amino acid (l-proline), presumably by taste-related mechanisms, elicits a satiety signal that in hypothalamus is translated into changes in cellular signalling and neuropeptides regulating food intake, ultimately resulting in decreased food intake.
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Affiliation(s)
- Sara Comesaña
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Marta Conde-Sieira
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Cristina Velasco
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, 36310 Vigo, Spain
| | - Sofia Morais
- Lucta S.A., Innovation Division, UAB Research Park, 08193 Bellaterra, Spain
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11
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Leach K, Hannan FM, Josephs TM, Keller AN, Møller TC, Ward DT, Kallay E, Mason RS, Thakker RV, Riccardi D, Conigrave AD, Bräuner-Osborne H. International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function. Pharmacol Rev 2020; 72:558-604. [PMID: 32467152 PMCID: PMC7116503 DOI: 10.1124/pr.119.018531] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Fadil M Hannan
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Thor C Møller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Donald T Ward
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Enikö Kallay
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rebecca S Mason
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rajesh V Thakker
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Daniela Riccardi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Arthur D Conigrave
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Hans Bräuner-Osborne
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
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L-phenylalanine Increased Gut Hormone Secretion through Calcium-Sensing Receptor in the Porcine Duodenum. Animals (Basel) 2019; 9:ani9080476. [PMID: 31344840 PMCID: PMC6719913 DOI: 10.3390/ani9080476] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/13/2019] [Accepted: 07/20/2019] [Indexed: 12/11/2022] Open
Abstract
Simple Summary The proper modulation of feed intake not only meets the nutrient requirement for the maximum growth rate in pigs, but also avoids feed waste. A complete understanding of how dietary factors affect the appetite in pigs will provide a strategy to modulate the feed intake of pigs. L-phenylalanine (L-Phe) has been demonstrated to induce satiety through stimulating anorectic hormone secretion in rodents. However, whether L-Phe has similar effects in pigs is unknown. Here, we aimed to investigate how L-Phe affects gut hormone secretion, along with insight into the underlying mechanism in porcine duodenum by using an in vitro perfusion system. Results showed that 80 mM L-Phe triggered glucose-dependent insulinotropic peptide (GIP) and cholecystokinin (CCK) release, and also upregulated calcium-sensing receptor (CaSR) and its downstream molecules, such as protein kinase C (PKC) and inositol 1,4,5-triphosphate receptor (IP3R) expression. However, these effects were attenuated by treatment with a CaSR antagonist. Our findings show that CaSR participates in Phe-induced hormone secretion in pig duodenum, indicating that CaSR may be a potential target in the food intake regulation of pigs. Abstract Luminal amino acids have a pivotal role in gut hormone secretion, and thereby modulate food intake and energy metabolism. However, the mechanisms by which amino acids exert this effect remains unknown. The purpose of this research was to investigate the response of L-phenylalanine (L-Phe) to gut hormone secretion and its underlying mechanisms by perfusing the pig duodenum. Eighty mM L-Phe and extracellular Ca2+ stimulated cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP) release, and upregulated the mRNA expression of the calcium-sensing receptor (CaSR), CCK, and GIP. Western blotting results showed that L-Phe also elevated the protein levels of CaSR, the inositol 1,4,5-triphosphate receptor (IP3R), and protein kinase C (PKC). However, the CaSR inhibitor NPS 2143 reduced the mRNA expression of CaSR, CCK, and GIP, and the secretion of CCK and GIP, as well as the protein level of CaSR, IP3R, and PKC. These results indicated that Phe stimulated gut secretion through a CaSR-mediated pathway and its downstream signaling molecules, PKC and IP3R.
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Mun HC, Leach KM, Conigrave AD. L-Amino Acids Promote Calcitonin Release via a Calcium-Sensing Receptor: Gq/11-Mediated Pathway in Human C-Cells. Endocrinology 2019; 160:1590-1599. [PMID: 31127815 DOI: 10.1210/en.2018-00860] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/19/2019] [Indexed: 11/19/2022]
Abstract
Human calcitonin release is promoted by elevated extracellular Ca2+ (Ca2+o) concentration acting, at least in part, via the calcium-sensing receptor (CaSR). The CaSR is positively modulated by L-amino acids, including the aromatic amino acids L-phenylalanine (Phe) and L-tryptophan (Trp). To investigate the effect of L-amino acids on human calcitonin secretion, we selected thyroid TT cells and exposed them to various Ca2+o concentrations in the absence or presence of L-Phe, plasma-like mixtures of L-amino acids, or the clinically effective positive modulator (calcimimetic) cinacalcet. In the presence of L-Phe or plasma-like mixtures of amino acids, TT cells exhibited enhanced Ca2+o sensitivity in assays of calcitonin release and intracellular Ca2+ mobilization. Furthermore, the effect of elevated Ca2+o and L-Phe on calcitonin release was markedly suppressed by the calcilytic NPS-2143. These effects were dependent on CaSR-mediated activation of Gq/11 as revealed by the specific inhibitor YM-254890. The findings support the hypothesis that calcitonin release is stimulated by increases in plasma L-amino acid levels as well as elevated Ca2+o concentration. They also demonstrate that stimulated calcitonin release as well as basal levels of calcitonin secretion are mediated by a CaSR:Gq/11 signaling mechanism.
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Affiliation(s)
- Hee-Chang Mun
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, Sydney, New South Wales, Australia
| | - Katie M Leach
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Arthur D Conigrave
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, Sydney, New South Wales, Australia
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14
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Involvement of calcium-sensing receptor activation in the alleviation of intestinal inflammation in a piglet model by dietary aromatic amino acid supplementation. Br J Nutr 2018; 120:1321-1331. [PMID: 30375295 DOI: 10.1017/s0007114518002891] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ca2+-sensing receptor (CaSR) represents a potential therapeutic target for inflammatory bowel diseases and strongly prefers aromatic amino acid ligands. We investigated the regulatory effects of dietary supplementation with aromatic amino acids - tryptophan, phenylalanine and tyrosine (TPT) - on the CaSR signalling pathway and intestinal inflammatory response. The in vivo study was conducted with weanling piglets using a 2 × 2 factorial arrangement in a randomised complete block design. Piglets were fed a basal diet or a basal diet supplemented with TPT and with or without inflammatory challenge. The in vitro study was performed in porcine intestinal epithelial cell line to investigate the effects of TPT on inflammatory response using NPS-2143 to inhibit CaSR. Dietary supplementation of TPT alleviated histopathological injury and decreased myeloperoxidase activity in intestine challenged with lipopolysaccharide. Dietary supplementation of TPT decreased serum concentration of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12, granulocyte-macrophage colony-stimulating factor, TNF-α), as well as the mRNA abundances of pro-inflammatory cytokines in intestine but enhanced anti-inflammatory cytokines IL-4 and transforming growth factor-β mRNA levels compared with pigs fed control diet and infected by lipopolysaccharide. Supplementation of TPT increased CaSR and phospholipase Cβ2 protein levels, but decreased inhibitor of NF-κB kinase α/β and inhibitor of NF-κB (IκB) protein levels in the lipopolysaccharide-challenged piglets. When the CaSR signalling pathway was blocked by NPS-2143, supplementation of TPT decreased the CaSR protein level, but enhanced phosphorylated NF-κB and IκB levels in IPEC-J2 cells. To conclude, supplementation of aromatic amino acids alleviated intestinal inflammation as mediated through the CaSR signalling pathway.
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15
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Ding KH, Cain M, Davis M, Bergson C, McGee-Lawrence M, Perkins C, Hardigan T, Shi X, Zhong Q, Xu J, Bollag WB, Hill W, Elsalanty M, Hunter M, Isales MC, Lopez P, Hamrick M, Isales CM. Amino acids as signaling molecules modulating bone turnover. Bone 2018; 115:15-24. [PMID: 29499416 PMCID: PMC6110952 DOI: 10.1016/j.bone.2018.02.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/25/2018] [Accepted: 02/26/2018] [Indexed: 10/17/2022]
Abstract
Except for the essential amino acids (AAs), much of the focus on adequate dietary protein intake has been on total nitrogen and caloric intake rather than AA composition. Recent data, however, demonstrate that "amino-acid sensing" can occur through either intracellular or extracellular nutrient-sensing mechanisms. In particular, members of the class 3 G-protein coupled receptor family, like the calcium-sensing receptor are known to preferentially bind specific AAs, which then modulate receptor activation by calcium ions and thus potentially impact bone turnover. In pursuing the possibility of direct nutrient effects on bone cells, we examined individual AA effects on osteoprogenitor/bone marrow stromal cells (BMSCs), a key target for bone anabolism. We demonstrate that BMSCs express both intracellular and extracellular nutrient sensing pathways and that AAs are required for BMSC survival. In addition, certain AA types, like members of the aromatic AAs, can potently stimulate increases in intracellular calcium and ERK phosphorylation/activation. Further, based on the in vitro data, we examined the effect of specific AAs on bone mass. To better evaluate the impact of specific AAs, we added these to a low-protein diet. Our data demonstrate that a low-protein diet itself is associated with a significant drop in bone mineral density (BMD) in the older mice, related, at least in part, to an increase in osteoclastic activity. This drop in BMD in mice on the low-protein diet is prevented by addition of AAs from the aromatic group. Taken together our data show that AAs function as specific and selective signaling molecules in bone cells.
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Affiliation(s)
- Ke-Hong Ding
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, USA
| | - Michael Cain
- Department of Orthopaedic Surgery, Medical College of Georgia, Augusta University, USA
| | - Michael Davis
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA
| | - Clare Bergson
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, USA
| | - Meghan McGee-Lawrence
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Orthopaedic Surgery, Medical College of Georgia, Augusta University, USA; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, USA
| | - Crystal Perkins
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA
| | - Trevor Hardigan
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA
| | - Xingming Shi
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, USA
| | - Qing Zhong
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, USA
| | - Jianrui Xu
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, USA
| | - Wendy B Bollag
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Medicine, Medical College of Georgia, Augusta University, USA; Department of Physiology, Medical College of Georgia, Augusta University, USA; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, USA; Charlie Norwood VA Medical Center, School of Dental Medicine, Augusta, GA 30912, USA
| | - William Hill
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Orthopaedic Surgery, Medical College of Georgia, Augusta University, USA; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, USA; Charlie Norwood VA Medical Center, School of Dental Medicine, Augusta, GA 30912, USA
| | - Mohammed Elsalanty
- Department of Oral Biology, School of Dental Medicine, Augusta, GA 30912, USA
| | - Monte Hunter
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Orthopaedic Surgery, Medical College of Georgia, Augusta University, USA
| | - Maria C Isales
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA
| | - Patricia Lopez
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA
| | - Mark Hamrick
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Orthopaedic Surgery, Medical College of Georgia, Augusta University, USA; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, USA
| | - Carlos M Isales
- Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Augusta University, USA; Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, USA; Department of Orthopaedic Surgery, Medical College of Georgia, Augusta University, USA; Department of Medicine, Medical College of Georgia, Augusta University, USA; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, USA.
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Zhao X, Xian Y, Wang C, Ding L, Meng X, Zhu W, Hang S. Calcium-sensing receptor-mediated L-tryptophan-induced secretion of cholecystokinin and glucose-dependent insulinotropic peptide in swine duodenum. J Vet Sci 2018; 19:179-187. [PMID: 29284209 PMCID: PMC5879066 DOI: 10.4142/jvs.2018.19.2.179] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/17/2017] [Accepted: 12/26/2017] [Indexed: 12/31/2022] Open
Abstract
This study aimed to elucidate the effect of tryptophan (Trp) on gut hormone secretion as well as the roles of the calcium-sensing receptor (CaSR) and its downstream signaling pathway in gut hormone secretion by assessing swine duodenal perfusion in vitro. Swine duodenum was perfused with Krebs-Henseleit buffer as a basal solution. Various concentrations (0, 10, and 20 mM) of Trp were applied to investigate its effect on gut hormone secretion. A CaSR antagonist was used to detect the involvement of CaSR and its signal molecules. The 20 mM Trp concentration promoted the secretion of cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP), elevated the mRNA level of CaSR, and upregulated the protein levels of CaSR, protein kinase C (PKC), and inositol trisphosphate receptor (IP3R). However, NPS 2143, an inhibitor of CaSR, attenuated the CCK and GIP release, reduced the mRNA level of CaSR, and decreased the protein levels of CaSR, PKC, and IP3R with 20 mM Trp perfusion. The results indicate that CCK and GIP secretion can be induced by Trp in swine duodenum in vitro, and the effect is mediated by CaSR and its downstream signal molecules PKC and IP3R.
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Affiliation(s)
- Xiuying Zhao
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yihan Xian
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Chao Wang
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Liren Ding
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Xianglong Meng
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Weiyun Zhu
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Suqin Hang
- Laboratory of Gastrointestinal Microbiology, Nanjing Agricultural University, Nanjing 210095, China
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Ferraretto A, Bottani M, Villa I, Giusto L, Signo M, Senesi P, Montesano A, Vacante F, Luzi L, Rubinacci A, Terruzzi I. L-Carnitine activates calcium signaling in human osteoblasts. J Funct Foods 2018. [DOI: 10.1016/j.jff.2018.05.068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Im YN, Lee YD, Park JS, Kim HK, Im SY, Song HR, Lee HK, Han MK. GPCR Kinase (GRK)-2 Is a Key Negative Regulator of Itch: l-Glutamine Attenuates Itch via a Rapid Induction of GRK2 in an ERK-Dependent Way. J Invest Dermatol 2018. [PMID: 29530536 DOI: 10.1016/j.jid.2018.02.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many itch mediators activate GPCR and trigger itch via activation of GPCR-mediated signaling pathways. GPCRs are desensitized by GPCR kinases (GRKs). The aim of this study is to explore the role of GRKs in itch response and the link between GRKs and glutamine, an amino acid previously shown to be an itch reliever. Itch responses were evoked by histamine, chloroquine, and dinitrochlorobenzene-induced contact dermatitis (CD). Phosphorylation and protein expression were detected by immunofluorescent staining and Western blotting. GRK2 knockdown using small interfering RNA enhanced itch responses evoked by histamine, chloroquine, and dinitrochlorobenzene-induced CD, whereas GRK2 overexpression using GRK2-expressing adenovirus reduced the itch responses. Glutamine reduced all itch evoked by histamine, chloroquine, and dinitrochlorobenzene-induced CD. Glutamine-mediated inhibition of itch was abolished by GRK2 knockdown. Glutamine application resulted in a rapid and strong expression of GRK2 in not only dinitrochlorobenzene-induced CD (within 10 minutes) but also cultured rat dorsal root ganglion cells, F11 (within 1 minute). ERK inhibitor abrogates glutamine-mediated GRK2 expression and inhibition of itch in dinitrochlorobenzene-induced CD. Our data indicate that GRK2 is a key negative regulator of itch and that glutamine attenuates itch via a rapid induction of GRK2 in an ERK-dependent way.
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Affiliation(s)
- Yu-Na Im
- Department of Immunology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Yu-Dong Lee
- Department of Immunology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Jeong-Soo Park
- Department of Immunology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Hae-Kyoung Kim
- Department of Immunology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Suhn-Young Im
- Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju, Republic of Korea
| | - Hwa-Ryung Song
- Department of Microbiology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Hern-Ku Lee
- Department of Microbiology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea.
| | - Myung-Kwan Han
- Department of Microbiology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea.
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19
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Xie X, Zhu T, Chen L, Ding S, Chu H, Wang J, Yao H, Chao J. MCPIP1-induced autophagy mediates ischemia/reperfusion injury in endothelial cells via HMGB1 and CaSR. Sci Rep 2018; 8:1735. [PMID: 29379093 PMCID: PMC5788920 DOI: 10.1038/s41598-018-20195-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 01/16/2018] [Indexed: 11/25/2022] Open
Abstract
Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) plays a important role in ischemia/reperfusion (I/R) injury. Autophagy is involved in activating endothelial cells in response to I/R. However, researchers have not clearly determined whether MCPIP1 mediates I/R injury in endothelial cells via autophagy, and its downstream mechanism remains unclear. Western blotting analyses and immunocytochemistry were applied to detect protein levels were detected in HUVECs. An in vitro scratch assay was used to detect cell migration. Cells were transfected with siRNAs to knockdown MCPIP1 and high mobility group box 1 (HMGB1) expression. The pharmacological activator of autophagy rapamycin and the specific calcium-sensing receptor (CaSR) inhibitor NPS-2143 were used to confirm the roles of autophagy and CaSR in I/R injury. I/R induced HMGB1 and CaSR expression, which subsequently upreguated the migration and apoptosis of HUVECs and coincided with the increase of autophagy. HMGB1 was involved in cell migration, whereas CaSR specifically participated in I/R-induced HUVEC apoptosis. Based on these findings, I/R-induced MCPIP1 expression regulates the migration and apoptosis of HUVECs via HMGB1 and CaSR, respectively, suggesting a new therapeutic targetof I/R injury.
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Affiliation(s)
- Xiaolong Xie
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China
| | - Tiebing Zhu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China. .,Department of Physiology, Medical School of Southeast University, Nanjing, Jiangsu, 210009, China.
| | - Lulu Chen
- Department of Physiology, Medical School of Southeast University, Nanjing, Jiangsu, 210009, China
| | - Shuang Ding
- Department of Physiology, Medical School of Southeast University, Nanjing, Jiangsu, 210009, China
| | - Han Chu
- Department of Physiology, Medical School of Southeast University, Nanjing, Jiangsu, 210009, China
| | - Jing Wang
- Department of Physiology, Medical School of Southeast University, Nanjing, Jiangsu, 210009, China
| | - Honghong Yao
- Department of Pharmacology, School of Medicine, Southeast University, Nanjing, Jiangsu, 210009, China.,Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu, 210096, China
| | - Jie Chao
- Department of Physiology, Medical School of Southeast University, Nanjing, Jiangsu, 210009, China. .,Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu, 210096, China. .,Department of Respiration, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, 210009, China.
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Abstract
Obesity is a major global health issue. High-protein diets have been shown to be associated with weight loss and satiety. The precise mechanism by which protein-rich diets promote weight loss remains unclear. Evidence suggests amino acids, formed as a consequence of protein digestion, are sensed by specific receptors on L-cells in the gastrointestinal (GI) tract. These L-cells respond by secreting gut hormones that subsequently induce satiety. In recent years, the calcium-sensing receptor has been identified in several cells of the GI tract, including L-cells, and suggested to sense specific amino acids. This review evaluates the evidence for protein-rich diets in inducing weight loss and how the calcium-sensing receptor may be implicated in this phenomenon. Commandeering the mechanisms by which elements of a protein-rich diet suppress appetite may provide another successful avenue for developing anti-obesity drugs.
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Affiliation(s)
- Utkarsh Ojha
- Faculty of Medicine, Imperial College School of Medicine, Imperial College London, London, UK
- Correspondence: Utkarsh Ojha, Faculty of Medicine, Imperial College School of Medicine, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London SW7 2AZ, UK, Tel +44 775 966 7685, Email
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21
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Petersen KU. Pepsin and Its Importance for Functional Dyspepsia: Relic, Regulator or Remedy? Dig Dis 2017; 36:98-105. [PMID: 28982106 DOI: 10.1159/000481399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/06/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND Functional dyspepsia is a heterogeneous disorder lacking an established therapeutic strategy. Historical treatment attempts with pepsin products were shrugged off, as a simple calculation shows that quantitative substitution is pointless. However, such attempts might have been right for the wrong reason. SUMMARY Today, the role of pepsins is primarily seen in the provision of signalling amino acids (especially phenylalanine and tryptophan) and peptides, which initiate processes promoting digestion. Proteolysis benefits from pepsin variants showing, contrary to common belief, activities of up to a pH value of 5.0. Non-clinical and clinical studies support the view that liberated amino acids produce a variety of direct and indirect effects. Signal chains stimulated by (mostly aromatic) amino acids lead to secretion of gastrin and cholecystokinin (CCK), mediated, respectively, by CCK2 (gastrin) and Ca2+-sensing receptors in the parietal cell, and Ca2+-sensing receptors in the antral and duodenal mucosa. Thus, CCK effects such as secretion of pancreatic enzymes and promotion of gastric accommodation are (also) consequential to peptic liberation of amino acids. Key Message: As functional dyspepsia represents a heterogeneous disorder, it may be intriguing to view pepsin as a potential (although still to be proven) treatment modality, distinguished by a diversity of pro-digestive effects.
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22
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Alamshah A, Spreckley E, Norton M, Kinsey-Jones JS, Amin A, Ramgulam A, Cao Y, Johnson R, Saleh K, Akalestou E, Malik Z, Gonzalez-Abuin N, Jomard A, Amarsi R, Moolla A, Sargent PR, Gray GW, Bloom SR, Murphy KG. l-phenylalanine modulates gut hormone release and glucose tolerance, and suppresses food intake through the calcium-sensing receptor in rodents. Int J Obes (Lond) 2017; 41:1693-1701. [PMID: 28792489 PMCID: PMC5678004 DOI: 10.1038/ijo.2017.164] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 05/26/2017] [Accepted: 06/21/2017] [Indexed: 12/11/2022]
Abstract
OBJECTIVE High-protein diets (HPDs) are associated with greater satiety and weight loss than diets rich in other macronutrients. The exact mechanisms by which HPDs exert their effects are unclear. However, evidence suggests that the sensing of amino acids produced as a result of protein digestion may have a role in appetite regulation and satiety. We investigated the effects of l-phenylalanine (L-Phe) on food intake and glucose homeostasis in rodents. METHODS We investigated the effects of the aromatic amino-acid and calcium-sensing receptor (CaSR) agonist l-phenylalanine (L-Phe) on food intake and the release of the gastrointestinal (GI) hormones peptide YY (PYY), glucagon-like peptide-1 (GLP-1) and ghrelin in rodents, and the role of the CaSR in mediating these effects in vitro and in vivo. We also examined the effect of oral l-Phe administration on glucose tolerance in rats. RESULTS Oral administration of l-Phe acutely reduced food intake in rats and mice, and chronically reduced food intake and body weight in diet-induced obese mice. Ileal l-Phe also reduced food intake in rats. l-Phe stimulated GLP-1 and PYY release, and reduced plasma ghrelin, and also stimulated insulin release and improved glucose tolerance in rats. Pharmacological blockade of the CaSR attenuated the anorectic effect of intra-ileal l-Phe in rats, and l-Phe-induced GLP-1 release from STC-1 and primary L cells was attenuated by CaSR blockade. CONCLUSIONS l-Phe reduced food intake, stimulated GLP-1 and PYY release, and reduced plasma ghrelin in rodents. Our data provide evidence that the anorectic effects of l-Phe are mediated via the CaSR, and suggest that l-Phe and the CaSR system in the GI tract may have therapeutic utility in the treatment of obesity and diabetes. Further work is required to determine the physiological role of the CaSR in protein sensing in the gut, and the role of this system in humans.
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Affiliation(s)
- A Alamshah
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - E Spreckley
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - M Norton
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - J S Kinsey-Jones
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - A Amin
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - A Ramgulam
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - Y Cao
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - R Johnson
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - K Saleh
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - E Akalestou
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - Z Malik
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - N Gonzalez-Abuin
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - A Jomard
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - R Amarsi
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - A Moolla
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK.,Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | | | | | - S R Bloom
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - K G Murphy
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Hammersmith Hospital, Imperial College London, London, UK
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23
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Julliard AK, Al Koborssy D, Fadool DA, Palouzier-Paulignan B. Nutrient Sensing: Another Chemosensitivity of the Olfactory System. Front Physiol 2017; 8:468. [PMID: 28747887 PMCID: PMC5506222 DOI: 10.3389/fphys.2017.00468] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/19/2017] [Indexed: 12/31/2022] Open
Abstract
Olfaction is a major sensory modality involved in real time perception of the chemical composition of the external environment. Olfaction favors anticipation and rapid adaptation of behavioral responses necessary for animal survival. Furthermore, recent studies have demonstrated that there is a direct action of metabolic peptides on the olfactory network. Orexigenic peptides such as ghrelin and orexin increase olfactory sensitivity, which in turn, is decreased by anorexigenic hormones such as insulin and leptin. In addition to peptides, nutrients can play a key role on neuronal activity. Very little is known about nutrient sensing in olfactory areas. Nutrients, such as carbohydrates, amino acids, and lipids, could play a key role in modulating olfactory sensitivity to adjust feeding behavior according to metabolic need. Here we summarize recent findings on nutrient-sensing neurons in olfactory areas and delineate the limits of our knowledge on this topic. The present review opens new lines of investigations on the relationship between olfaction and food intake, which could contribute to determining the etiology of metabolic disorders.
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Affiliation(s)
- A-Karyn Julliard
- Univ Lyon, Université Claude Bernard Lyon1, Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM U1028/Centre National de la Recherche Scientifique UMR5292 Team Olfaction: From Coding to MemoryLyon, France
| | - Dolly Al Koborssy
- Department of Biological Science, Florida State UniversityTallahassee, FL, United States.,Program in Neuroscience, Florida State UniversityTallahassee, FL, United States
| | - Debra A Fadool
- Department of Biological Science, Florida State UniversityTallahassee, FL, United States.,Program in Neuroscience, Florida State UniversityTallahassee, FL, United States.,Institute of Molecular Biophysics, Florida State UniversityTallahassee, FL, United States
| | - Brigitte Palouzier-Paulignan
- Univ Lyon, Université Claude Bernard Lyon1, Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM U1028/Centre National de la Recherche Scientifique UMR5292 Team Olfaction: From Coding to MemoryLyon, France
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24
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Conigrave AD. The Calcium-Sensing Receptor and the Parathyroid: Past, Present, Future. Front Physiol 2016; 7:563. [PMID: 28018229 PMCID: PMC5156698 DOI: 10.3389/fphys.2016.00563] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 11/07/2016] [Indexed: 12/13/2022] Open
Abstract
Parathyroid hormone (PTH) defends the extracellular fluid from hypocalcemia and has powerful and well-documented actions on the skeleton and renal tubular system. To achieve a satisfactory stable plasma calcium level, the secretion of PTH, and the resulting serum PTH level, is titrated carefully to the prevailing plasma ionized Ca2+ concentration via a Ca2+ sensing mechanism that mediates feedback inhibition of PTH secretion. Herein, I consider the properties of the parathyroid Ca2+ sensing mechanism, the identity of the Ca2+ sensor, the intracellular biochemical mechanisms that it controls, the manner of its integration with other components of the PTH secretion control mechanism, and its modulation by other nutrients. Together the well-established, recently elucidated, and yet-to-be discovered elements of the story constitute the past, present, and future of the parathyroid and its calcium-sensing receptor (CaSR).
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Affiliation(s)
- Arthur D Conigrave
- Faculties of Science and Medicine, School of Life and Environmental Sciences, Charles Perkins Centre, University of Sydney Sydney, NSW, Australia
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25
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Wang YJ, Yan J, Yin F, Li L, Qin YG, Meng CY, Lu RF, Guo L. Role of autophagy in cadmium-induced testicular injury. Hum Exp Toxicol 2016; 36:1039-1048. [PMID: 27872163 DOI: 10.1177/0960327116678300] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The testis is sensitive to cadmium, but studies investigating cadmium-induced testicular injury have not yet clearly revealed the underlying mechanisms. This study aimed to investigate the injurious effects of cadmium on rat testes and the role that autophagy plays in this process. Wistar rats were randomly divided into four groups and intraperitoneally injected with 0.2 (low), 0.4 (middle), and 0.8 mg/kg·body weight (high) cadmium chloride for 5 weeks, while the control rats were injected with equal volume of saline. Rats exposed to cadmium appeared inactive and had reduced body weights and increased testicular organ coefficients at the end of treatment compared with control rats. Atomic absorption results showed that cadmium levels increased with increased cadmium exposure. Hematoxylin and eosin staining of testicular sections showed seminiferous tubular atrophy, decreased pipe diameter, spermatogonial stem cells falling off the inner lining, and reduced germ cell layers of disorderly arrangements in cadmium-treated rats. Immunohistochemical and western blot results both showed that levels of the autophagy-related proteins Beclin1 and microtubule-associated protein 1 light chain 3B (LC3B) increased with increased cadmium exposure. We also found that LC3B-II and calcium-sensing receptor (CSR) levels in cadmium-exposed rats significantly increased. By immunofluorescence, we found that the percentage of cells that expressed the CSR was significantly higher in LC3B-positive than LC3B-negative cells. Together, our results showed that cadmium accumulates in the testes causing testicular injury, which may be related to increased autophagy levels. Furthermore, calcium disorders associated with the CSR may reveal a potential way to activate autophagy.
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Affiliation(s)
- Y-J Wang
- 1 Department of Toxicology, School of Public Health, Jilin University, Changchun, China
| | - J Yan
- 1 Department of Toxicology, School of Public Health, Jilin University, Changchun, China
| | - F Yin
- 2 Department of Orthopaedics, China-Japan Union Hospital, Jilin University, Changchun, China
| | - L Li
- 1 Department of Toxicology, School of Public Health, Jilin University, Changchun, China
| | - Y-G Qin
- 1 Department of Toxicology, School of Public Health, Jilin University, Changchun, China
| | - C-Y Meng
- 2 Department of Orthopaedics, China-Japan Union Hospital, Jilin University, Changchun, China
| | - R-F Lu
- 1 Department of Toxicology, School of Public Health, Jilin University, Changchun, China
| | - L Guo
- 1 Department of Toxicology, School of Public Health, Jilin University, Changchun, China
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26
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Zhang C, Miller CL, Gorkhali R, Zou J, Huang K, Brown EM, Yang JJ. Molecular Basis of the Extracellular Ligands Mediated Signaling by the Calcium Sensing Receptor. Front Physiol 2016; 7:441. [PMID: 27746744 PMCID: PMC5043022 DOI: 10.3389/fphys.2016.00441] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 09/16/2016] [Indexed: 12/20/2022] Open
Abstract
Ca2+-sensing receptors (CaSRs) play a central role in regulating extracellular calcium concentration ([Ca2+]o) homeostasis and many (patho)physiological processes in multiple organs. This regulation is orchestrated by a cooperative response to extracellular stimuli such as small changes in Ca2+, Mg2+, amino acids, and other ligands. In addition, CaSR is a pleiotropic receptor regulating several intracellular signaling pathways, including calcium mobilization and intracellular calcium oscillation. Nearly 200 mutations and polymorphisms have been found in CaSR in relation to a variety of human disorders associated with abnormal Ca2+ homeostasis. In this review, we summarize efforts directed at identifying binding sites for calcium and amino acids. Both homotropic cooperativity among multiple calcium binding sites and heterotropic cooperativity between calcium and amino acid were revealed using computational modeling, predictions, and site-directed mutagenesis coupled with functional assays. The hinge region of the bilobed Venus flytrap (VFT) domain of CaSR plays a pivotal role in coordinating multiple extracellular stimuli, leading to cooperative responses from the receptor. We further highlight the extensive number of disease-associated mutations that have also been shown to affect CaSR's cooperative action via several types of mechanisms. These results provide insights into the molecular bases of the structure and functional cooperativity of this receptor and other members of family C of the G protein-coupled receptors (cGPCRs) in health and disease states, and may assist in the prospective development of novel receptor-based therapeutics.
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Affiliation(s)
- Chen Zhang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | | | - Rakshya Gorkhali
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Juan Zou
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Kenneth Huang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Edward M Brown
- Center for Diagnostics and Therapeutics, Georgia State UniversityAtlanta, GA, USA; Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's HospitalBoston, MA, USA
| | - Jenny J Yang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
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27
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Stubenrauch JA, Mevissen C, Schulte MF, Bochenek S, Albrecht M, Subramanian PS. Highly specific “sensing” of tryptophan by a luminescent europium(III) complex. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2016. [DOI: 10.1515/znb-2016-0096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The europium(III) complex 1-Cl3 (S,S-2,2′-(((1,10-phenanthroline-2,9-diyl)bis(methanylylidene))bis(azanylylidene))bis(3-methylbutanamide)europiumtrichloride) undergoes, only in the presence of the amino acid tryptophan, a change of emission at 615 nm. In the presence of few equivalents of tryptophan, emission of the europium complex is enhanced while it disappears upon addition of large amounts. This behavior can be assigned to displacement of the sensitizing phenanthroline ligand of 1-Cl2•Trp in the latter case.
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Affiliation(s)
- Jan A. Stubenrauch
- Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany
| | - Christian Mevissen
- Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany
| | - Marie F. Schulte
- Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany
| | - Steffen Bochenek
- Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany
| | - Markus Albrecht
- Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany
| | - Palani S. Subramanian
- Central Salt and Marine Chemicals, Research Institute (CSRI), Bhavnagar, 364 002, Gujarat, India
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28
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Medina J, Nakagawa Y, Nagasawa M, Fernandez A, Sakaguchi K, Kitaguchi T, Kojima I. Positive Allosteric Modulation of the Calcium-sensing Receptor by Physiological Concentrations of Glucose. J Biol Chem 2016; 291:23126-23135. [PMID: 27613866 DOI: 10.1074/jbc.m116.729863] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 01/08/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is activated by various cations, cationic compounds, and amino acids. In the present study we investigated the effect of glucose on CaSR in HEK293 cells stably expressing human CaSR (HEK-CaSR cells). When glucose concentration in the buffer was raised from 3 to 25 mm, a rapid elevation of cytoplasmic Ca2+ concentration ([Ca2+]c) was observed. This elevation was immediate and transient and was followed by a sustained decrease in [Ca2+]c The effect of glucose was detected at a concentration of 4 mm and reached its maximum at 5 mm 3-O-Methylglucose, a non-metabolizable analogue of glucose, reproduced the effect of glucose. Sucrose also induced an elevation of [Ca2+]c in HEK-CaSR cells. Similarly, sucralose was nearly as effective as glucose in inducing elevation of [Ca2+]c Glucose was not able to increase [Ca2+]c in the absence of extracellular Ca2+ The effect of glucose on [Ca2+]c was inhibited by NPS-2143, an allosteric inhibitor of CaSR. In addition, NPS-2143 also inhibited the [Ca2+]c responses to sucralose and sucrose. Glucose as well as sucralose decreased cytoplasmic cAMP concentration in HEK-CaSR cells. The reduction of cAMP induced by glucose was blocked by pertussis toxin. Likewise, sucralose reduced [cAMP]c Finally, glucose increased [Ca2+]c in PT-r parathyroid cells and in Madin-Darby canine kidney cells, both of which express endogenous CaSR. These results indicate that glucose acts as a positive allosteric modulator of CaSR.
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Affiliation(s)
- Johan Medina
- From the Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Yuko Nakagawa
- From the Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Masahiro Nagasawa
- From the Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Anny Fernandez
- From the Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Kazushige Sakaguchi
- Institute of Advanced Medicine, Wakayama Medical University, Wakayama 641-8509, Japan
| | - Tetsuya Kitaguchi
- Waseda Bioscience Research Institute in Singapore Singapore 138667, and.,Organization for University Research Initiatives, Waseda University, Tokyo 162-0041, Japan
| | - Itaru Kojima
- From the Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan,
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29
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Protein/amino-acid modulation of bone cell function. BONEKEY REPORTS 2016; 5:827. [PMID: 28149508 PMCID: PMC5238414 DOI: 10.1038/bonekey.2016.58] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 06/24/2016] [Indexed: 01/07/2023]
Abstract
Nutrients (protein, carbohydrates and fats) have traditionally been thought of as fuels simply providing the energy for cellular metabolic activity. According to the classic view, if nutrients are available, then anabolic pathways are activated, and if nutrients are not available, catabolic pathways are activated. However, it is becoming increasingly clear that nutrient effects on bone cells (stem cells, osteoblasts and osteoclasts) are complex, some nutrients promote bone formation, whereas others interfere with bone formation or actually promote bone break down. At an organ level, nutrient intake can suppress bone breakdown and modulate the activity of the calcium/vitamin D/parathyroid hormone axis. At a cellular level, nutrient intake can impact cellular energetics either through a direct mechanism (binding or uptake of the nutrient into the cell) or indirect (by elevating nutrient-related hormones such as insulin, insulin-like growth factor 1 or incretin hormones). It is also becoming clear that within a nutrient class (for example, protein), individual components (that is, amino acids) can have markedly different effects on cell function and impact bone formation. The focus of this review will be on one nutrient class in particular, dietary protein. As the prevalence of inadequate dietary protein intake increases with age, these findings may have translational implications as to the optimal dietary protein content in the setting of age-associated bone loss.
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Ayush O, Jin ZW, Kim HK, Shin YR, Im SY, Lee HK. Glutamine up-regulates MAPK phosphatase-1 induction via activation of Ca 2+→ ERK cascade pathway. Biochem Biophys Rep 2016; 7:10-19. [PMID: 28955885 PMCID: PMC5613282 DOI: 10.1016/j.bbrep.2016.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 05/09/2016] [Accepted: 05/11/2016] [Indexed: 11/25/2022] Open
Abstract
The non-essential amino acid L-glutamine (Gln) displays potent anti-inflammatory activity by deactivating p38 mitogen activating protein kinase and cytosolic phospholipase A2 via induction of MAPK phosphatase-1 (MKP-1) in an extracellular signal-regulated kinase (ERK)-dependent way. In this study, the mechanism of Gln-mediated ERK-dependency in MKP-1 induction was investigated. Gln increased ERK phosphorylation and activity, and phosphorylations of Ras, c-Raf, and MEK, located in the upstream pathway of ERK, in response to lipopolysaccharidein vitro and in vivo. Gln-induced dose-dependent transient increases in intracellular calcium ([Ca2+]i) in MHS macrophage cells. Ionomycin increased [Ca2+]i and activation of Ras → ERK pathway, and MKP-1 induction, in the presence, but not in the absence, of LPS. The Gln-induced pathways involving Ca2+→ MKP-1 induction were abrogated by a calcium blocker. Besides Gln, other amino acids including L-phenylalanine and l-cysteine (Cys) also induced Ca2+ response, activation of Ras → ERK, and MKP-1 induction, albeit to a lesser degree. Gln and Cys were comparable in suppression against 2, 4-dinitrofluorobenzene-induced contact dermatitis. Gln-mediated, but not Cys-mediated, suppression was abolished by MKP-1 small interfering RNA. These data indicate that Gln induces MKP-1 by activating Ca2+→ ERK pathway, which plays a key role in suppression of inflammatory reactions.
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Key Words
- AP-1, activating protein 1
- Ala, alanine
- Asp, aspartate
- BAPTA, 1,2-bis(o-aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid tetraacetoxymethylester
- CD, contact dermatitis
- CaM, calmodulin
- CaR, Ca2+-sensing receptor
- DMSO, dimethyl sulfoxide
- DNFB, 1-fluoro-2,4-dinitrobenzene
- ERK, extracellular signal-regulated kinase
- ESR, ear swelling response
- Gln, L-glutamine
- Glu, glutamate
- Gly, glycine
- H&E, hematoxylin and eosin
- JNK, c-Jun N-terminal kinase
- L-Glutamine
- LPS, lipopolysaccharides
- MAPK Phosphatase-1
- MAPK, mitogen activated protein kinase
- MKP-1, MAPK phosphatase-1
- Mitogen-activated protein kinase
- PEI, polyethyleneimine
- Ras/c-Raf/MEK/ERK, extracellular-signal-regulated kinase
- [Ca2+]i, intracellular calcium concentration
- cPLA2, cytoplasmic phospholipase A2
- siRNA, small interfering RNA
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Affiliation(s)
- Otgonzaya Ayush
- Department of Dermatology, Medical University, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
| | - Zhe Wu Jin
- Department of Anatomy and Histology and Embryology, Yanbian University Medical College, YanJi City, Jilin Province, China
| | - Hae-Kyoung Kim
- Departments of Immunology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Yu-Rim Shin
- Biofoods Story, Inc, 477 Jeonjucheon-seoro, Wansan-gu, Jeonju, Jeonbuk 560-821, Republic of Korea
| | - Suhn-Young Im
- Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju, Republic of Korea
| | - Hern-Ku Lee
- Departments of Immunology and Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Republic of Korea
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Owen JL, Cheng SX, Ge Y, Sahay B, Mohamadzadeh M. The role of the calcium-sensing receptor in gastrointestinal inflammation. Semin Cell Dev Biol 2015; 49:44-51. [PMID: 26709005 DOI: 10.1016/j.semcdb.2015.10.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 12/13/2022]
Abstract
The gastrointestinal (GI) tract must balance the extraction of energy and metabolic end-products from ingested nutrition and resident gut microbes and the maintenance of a symbiotic relationship with this microbiota, with the ability to mount functional immune responses to pathogenic organisms to maintain GI health. The gut epithelium is equipped with bacteria-sensing mechanisms that discriminate between pathogenic and commensal microorganisms and regulate host responses between immunity and tolerance. The epithelium also expresses numerous nutrient-sensing receptors, but their importance in the preservation of the gut microbiota and immune homeostasis remains largely unexplored. Observations that a deficiency in the extracellular calcium-sensing receptor (CaSR) using intestinal epithelium-specific receptor knockout mice resulted in diminished intestinal barrier integrity, altered composition of the gut microbiota, modified expression of intestinal pattern recognition receptors, and a skewing of local and systemic innate responses from regulatory to stimulatory, may change the way that this receptor is considered as a potential immunotherapeutic target in gut homeostasis. These findings suggest that pharmacologic CaSR activators and CaSR-based nutrients such as calcium, polyamines, phenylalanine, tryptophan, and oligo-peptides might be useful in conditioning the gut microenvironment, and thus, in the prevention and treatment of disorders such as inflammatory bowel disease (IBD), infectious enterocolitis, and other inflammatory and secretory diarrheal diseases. Here, we review the emerging roles of the CaSR in intestinal homeostasis and its therapeutic potential for gut pathology.
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Affiliation(s)
- Jennifer L Owen
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Sam X Cheng
- Division of Gastroenterology, Department of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Yong Ge
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL, USA; Division of Hepatology, Gastroenterology, and Nutrition, University of Florida, Gainesville, FL, USA
| | - Bikash Sahay
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL, USA; Division of Hepatology, Gastroenterology, and Nutrition, University of Florida, Gainesville, FL, USA
| | - Mansour Mohamadzadeh
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL, USA; Division of Hepatology, Gastroenterology, and Nutrition, University of Florida, Gainesville, FL, USA.
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Procházková D, Jarkovský J, Haňková Z, Konečná P, Benáková H, Vinohradská H, Mikušková A. Long-term treatment for hyperphenylalaninemia and phenylketonuria: a risk for nutritional vitamin B12 deficiency? J Pediatr Endocrinol Metab 2015. [PMID: 26226119 DOI: 10.1515/jpem-2014-0489] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE The objective of the study was to determine the incidence of vitamin B12 deficiency in patients under long-term treatment for phenylketonuria (PKU) and hyperphenylalaninemia (HPA), as well as its associations with B12 vitamin parameters (holotranscobalamin - active vitamin B12, serum folate, total plasma homocysteine, and plasma methylmalonic acid concentration). PATIENTS AND METHODS The group consisted of 51 PKU (n=29) and HPA (n=22) patients aged 3-48 years (28 children, 23 adults). RESULTS A significant difference in serum folate levels was discovered between adult HPA patients and PKU patients (p=0.004, Mann-Whitney U-test). A significant difference in plasma homocysteine concentrations within the normal levels (p=0.032, χ2-test) was detected between adult HPA and PKU patients. In the group of adults, we also found significant differences in serum holotranscobalamin concentrations regarding both concentration levels and the proportion of patients with concentrations within the normal levels (p=0.031, Mann-Whitney U-test; p=0.006, χ2-test). CONCLUSION We have proven that adult patients with PKU and HPA are at risk of vitamin B12 nutritional deficiency. The most effective parameter for these adults is the monitoring of holotranscobalamin in the serum.
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Pekarova M, Lojek A. The crucial role of l-arginine in macrophage activation: What you need to know about it. Life Sci 2015; 137:44-8. [PMID: 26188591 DOI: 10.1016/j.lfs.2015.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 07/07/2015] [Accepted: 07/11/2015] [Indexed: 11/19/2022]
Abstract
Nowadays, it is well recognized that amino acids are powerful molecules responsible for regulatory control over fundamental cellular processes. However, our understanding of the signaling cascades involved in amino acid sensing in organisms, as well as signal initiation, is largely limited. This is also the case of semi-essential amino acid l-arginine, which has multiple metabolic fates, and it is considered as one of the most versatile amino acids. Recently, some new and important facts have been published considering the role of l-arginine in the regulation of inflammatory processes in several human and mouse models, mediated also via the regulation of macrophage activation. Therefore, this mini review focuses on the actual summarization of information about (i) l-arginine bioavailability in organism, (ii) l-arginine-dependent regulation of nitric oxide synthase expression and nitric oxide production, and importantly (iii) its role in the activation of intracellular signaling pathways and G-protein-coupled receptors in macrophages.
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Affiliation(s)
- Michaela Pekarova
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno, Czech Republic.
| | - Antonin Lojek
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno, Czech Republic
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Zhang C, Miller CL, Brown EM, Yang JJ. The calcium sensing receptor: from calcium sensing to signaling. SCIENCE CHINA-LIFE SCIENCES 2015; 58:14-27. [DOI: 10.1007/s11427-014-4779-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 10/21/2014] [Indexed: 12/14/2022]
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Photon atomic parameters of nonessential amino acids for radiotherapy and diagnostics. JOURNAL OF AMINO ACIDS 2014; 2014:434519. [PMID: 25548658 PMCID: PMC4273595 DOI: 10.1155/2014/434519] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 11/12/2014] [Indexed: 11/21/2022]
Abstract
The total mass attenuation coefficients (μt) (cm2/g) and atomic, molecular, and electronic effective cross sections have been calculated for nonessential amino acids that contain H, C, N, and O such as tyrosine, aspartate, glutamine, alanine, asparagine, aspartic acid, cysteine, and glycine in the wide energy region 0.015–15 MeV. The variations with energy of total mass attenuation coefficients and atomic, molecular, and electronic cross sections are shown for all photon interactions.
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Role of Ca2+ and L-Phe in regulating functional cooperativity of disease-associated "toggle" calcium-sensing receptor mutations. PLoS One 2014; 9:e113622. [PMID: 25420019 PMCID: PMC4242666 DOI: 10.1371/journal.pone.0113622] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 10/27/2014] [Indexed: 01/15/2023] Open
Abstract
The Ca2+-sensing receptor (CaSR) regulates Ca2+ homeostasis in the body by monitoring extracellular levels of Ca2+ ([Ca2+]o) and amino acids. Mutations at the hinge region of the N-terminal Venus flytrap domain (VFTD) produce either receptor inactivation (L173P, P221Q) or activation (L173F, P221L) related to hypercalcemic or hypocalcemic disorders. In this paper, we report that both L173P and P221Q markedly impair the functional positive cooperativity of the CaSR as reflected by [Ca2+]o–induced [Ca2+]i oscillations, inositol-1-phosphate (IP1) accumulation and extracellular signal-regulated kinases (ERK1/2) activity. In contrast, L173F and P221L show enhanced responsiveness of these three functional readouts to [Ca2+]o. Further analysis of the dynamics of the VFTD mutants using computational simulation studies supports disruption in the correlated motions in the loss-of-function CaSR mutants, while these motions are enhanced in the gain-of-function mutants. Wild type (WT) CaSR was modulated by L-Phe in a heterotropic positive cooperative way, achieving an EC50 similar to those of the two activating mutations. The response of the inactivating P221Q mutant to [Ca2+]o was partially rescued by L-Phe, illustrating the capacity of the L-Phe binding site to enhance the positive homotropic cooperativity of CaSR. L-Phe had no effect on the other inactivating mutant. Moreover, our results carried out both in silico and in intact cells indicate that residue Leu173, which is close to residues that are part of the L-Phe-binding pocket, exhibited impaired heterotropic cooperativity in the presence of L-Phe. Thus, Pro221 and Leu173 are important for the positive homo- and heterotropic cooperative regulation elicited by agonist binding.
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Zhang C, Zhuo Y, Moniz HA, Wang S, Moremen KW, Prestegard JH, Brown EM, Yang JJ. Direct determination of multiple ligand interactions with the extracellular domain of the calcium-sensing receptor. J Biol Chem 2014; 289:33529-42. [PMID: 25305020 DOI: 10.1074/jbc.m114.604652] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Numerous in vivo functional studies have indicated that the dimeric extracellular domain (ECD) of the CaSR plays a crucial role in regulating Ca(2+) homeostasis by sensing Ca(2+) and l-Phe. However, direct interaction of Ca(2+) and Phe with the ECD of the receptor and the resultant impact on its structure and associated conformational changes have been hampered by the large size of the ECD, its high degree of glycosylation, and the lack of biophysical methods to monitor weak interactions in solution. In the present study, we purified the glycosylated extracellular domain of calcium-sensing receptor (CaSR) (ECD) (residues 20-612), containing either complex or high mannose N-glycan structures depending on the host cell line employed for recombinant expression. Both glycosylated forms of the CaSR ECD were purified as dimers and exhibit similar secondary structures with ∼ 50% α-helix, ∼ 20% β-sheet content, and a well buried Trp environment. Using various spectroscopic methods, we have shown that both protein variants bind Ca(2+) with a Kd of 3.0-5.0 mm. The local conformational changes of the proteins induced by their interactions with Ca(2+) were visualized by NMR with specific (15)N Phe-labeled forms of the ECD. Saturation transfer difference NMR approaches demonstrated for the first time a direct interaction between the CaSR ECD and l-Phe. We further demonstrated that l-Phe increases the binding affinity of the CaSR ECD for Ca(2+). Our findings provide new insights into the mechanisms by which Ca(2+) and amino acids regulate the CaSR and may pave the way for exploration of the structural properties of CaSR and other members of family C of the GPCR superfamily.
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Affiliation(s)
- Chen Zhang
- From the Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30303
| | - You Zhuo
- From the Department of Chemistry
| | - Heather A Moniz
- the Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Shuo Wang
- the Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Kelley W Moremen
- the Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - James H Prestegard
- the Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Edward M Brown
- the Department of Medicine, Division of Endocrinology, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Jenny J Yang
- From the Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30303,
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38
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Forde BG, Roberts MR. Glutamate receptor-like channels in plants: a role as amino acid sensors in plant defence? F1000PRIME REPORTS 2014; 6:37. [PMID: 24991414 PMCID: PMC4075314 DOI: 10.12703/p6-37] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Plant glutamate receptor-like genes (GLRs) are homologous to the genes for mammalian ionotropic glutamate receptors (iGluRs), after which they were named, but in the 16 years since their existence was first revealed, progress in elucidating their biological role has been disappointingly slow. Recently, however, studies from a number of laboratories focusing on the model plant species Arabidopsis thaliana (L.) have thrown new light on the functional properties of some members of the GLR gene family. One important finding has been that plant GLR receptors have a much broader ligand specificity than their mammalian iGluR counterparts, with evidence that some individual GLR receptors can be gated by as many as seven amino acids. These results, together with the ubiquity of their expression throughout the plant, open up the possibility that GLR receptors could have a pervasive role in plants as non-specific amino acid sensors in diverse biological processes. Addressing what one of these roles could be, recent studies examining the wound response and disease susceptibility in GLR knockout mutants have provided evidence that some members of clade 3 of the GLR gene family encode important components of the plant's defence response. Ways in which this family of amino acid receptors might contribute to the plant's ability to respond to an attack from pests and pathogens are discussed.
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El Refaey M, Zhong Q, Hill WD, Shi XM, Hamrick MW, Bailey L, Johnson M, Xu J, Bollag WB, Chutkan N, Isales CM. Aromatic amino acid activation of signaling pathways in bone marrow mesenchymal stem cells depends on oxygen tension. PLoS One 2014; 9:e91108. [PMID: 24727733 PMCID: PMC3984069 DOI: 10.1371/journal.pone.0091108] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/07/2014] [Indexed: 01/22/2023] Open
Abstract
The physiologic oxygen pressures inside the bone marrow environment are much lower than what is present in the peripheral circulation, ranging from 1-7%, compared to values as high as 10-13% in the arteries, lungs and liver. Thus, experiments done with bone marrow mesenchymal stem cells (BMMSCs) using standard culture conditions may not accurately reflect the true hypoxic bone marrow microenvironment. However, since aging is associated with an increased generation of reactive oxygen species, experiments done under 21%O2 conditions may actually more closely resemble that of the aging bone marrow environment. Aromatic amino acids are known to be natural anti-oxidants. We have previously reported that aromatic amino acids are potent agonists for stimulating increases in intracellular calcium and phospho-c-Raf and in promoting BMMSC differentiation down the osteogenic pathway. Our previous experiments were performed under normoxic conditions. Thus, we next decided to compare a normoxic (21% O2) vs. a hypoxic environment (3% O2) alone or after treatment with aromatic amino acids. Reverse-phase protein arrays showed that 3% O2 itself up-regulated proliferative pathways. Aromatic amino acids had no additional effect on signaling pathways under these conditions. However, under 21%O2 conditions, aromatic amino acids could now significantly increase these proliferative pathways over this "normoxic" baseline. Pharmacologic studies are consistent with the aromatic amino acids activating the extracellular calcium-sensing receptor. The effects of aromatic amino acids on BMMSC function in the 21% O2 environment is consistent with a potential role for these amino acids in an aging environment as functional anti oxidants.
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Affiliation(s)
- Mona El Refaey
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
| | - Qing Zhong
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - William D. Hill
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Orthopaedic Surgery, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Xing-Ming Shi
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Orthopaedic Surgery, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Pathology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Mark W. Hamrick
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Orthopaedic Surgery, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Lakiea Bailey
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
| | - Maribeth Johnson
- Department of Biostatistics, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Jianrui Xu
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Orthopaedic Surgery, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Wendy B. Bollag
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Norman Chutkan
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Orthopaedic Surgery, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
| | - Carlos M. Isales
- Institute for Regenerative and Reparative Medicine, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Orthopaedic Surgery, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- * E-mail:
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Energy absorption and exposure buildup factors of essential amino acids. BIOMED RESEARCH INTERNATIONAL 2014; 2014:359754. [PMID: 24605325 PMCID: PMC3925512 DOI: 10.1155/2014/359754] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 12/08/2013] [Indexed: 11/30/2022]
Abstract
The effective atomic number and effective electron density in amino acids are of significant interest due to their use in various applications. The energy absorption buildup factors, exposure buildup factors, effective atomic numbers, and electron densities of essential amino acids such as Leucine (C6H13NO2), Lysine (C6H14N2O2), Methionine (C5H11NO2S), Phenylalanine (C9H11NO2), Threonine (C4H9NO3), Tryptophan (C11H12N2O2), Valine (C5H11NO2), Arginine (C6H14N4O2), and Histidine (C6H9N3O2) were determined theoretically in the energy range 0.015–15 MeV.
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Bihuniak JD, Sullivan RR, Simpson CA, Caseria DM, Huedo-Medina TB, O’Brien KO, Kerstetter JE, Insogna KL. Supplementing a low-protein diet with dibasic amino acids increases urinary calcium excretion in young women. J Nutr 2014; 144:282-8. [PMID: 24431325 PMCID: PMC3927545 DOI: 10.3945/jn.113.185009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/10/2013] [Accepted: 12/23/2013] [Indexed: 11/14/2022] Open
Abstract
Increasing dietary protein within a physiologic range stimulates intestinal calcium absorption, but it is not known if specific amino acids or dietary protein as a whole are responsible for this effect. Therefore, we selectively supplemented a low-protein (0.7 g/kg) diet with either the calcium-sensing receptor-activating amino acids (CaSR-AAAs) L-tryptophan, L-phenylalanine, and L-histidine, or the dibasic amino acids (DAAs) L-arginine and L-lysine, to achieve intakes comparable to the content of a high-protein diet (2.1 g/kg) and measured intestinal calcium absorption. Fourteen young women took part in a placebo-controlled, double-blind, crossover feeding trial in which each participant ingested a 6-d low-protein diet supplemented with CaSR-AAAs, DAAs, or methylcellulose capsules (control) after an 11-d adjustment period. All participants ingested all 3 diets in random order. Intestinal calcium absorption was measured between days 5 and 6 using dual-stable calcium isotopes ((42)Ca, (43)Ca, and (44)Ca). There was no difference in calcium absorption between the diet supplemented with CaSR-AAAs (22.9 ± 2.0%) and the control diet (22.3 ± 1.4%) (P = 0.64). However, calcium absorption tended to be greater during the DAA supplementation period (25.2 ± 1.4%) compared with the control diet period (22.3 ± 1.4%) (P < 0.10). Larger and longer clinical trials are needed to clarify the possible benefit of arginine and lysine on calcium absorption.
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Affiliation(s)
| | | | | | | | | | | | - Jane E. Kerstetter
- Department of Allied Health Sciences, University of Connecticut, Storrs, CT
| | - Karl L. Insogna
- Department of Internal Medicine, Section of Endocrinology and
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42
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Abstract
As a signalling molecule, glutamate is best known for its role as a fast excitatory neurotransmitter in the mammalian nervous system, a role that requires the activity of a family of ionotropic glutamate receptors (iGluRs). The unexpected discovery in 1998 that Arabidopsis thaliana L. possesses a family of iGluR-related (GLR) genes laid the foundations for an assessment of glutamate's potential role as a signalling molecule in plants that is still in progress. Recent advances in elucidating the function of Arabidopsis GLR receptors has revealed similarities with iGluRs in their channel properties, but marked differences in their ligand specificities. The ability of plant GLR receptors to act as amino-acid-gated Ca(2+) channels with a broad agonist profile, combined with their expression throughout the plant, makes them strong candidates for a multiplicity of amino acid signalling roles. Although root growth is inhibited in the presence of a number of amino acids, only glutamate elicits a specific sequence of changes in growth, root tip morphology, and root branching. The recent finding that the MEKK1 gene is a positive regulator of glutamate sensitivity at the root tip has provided genetic evidence for the existence in plants of a glutamate signalling pathway analogous to those found in animals. This short review will discuss the most recent advances in understanding glutamate signalling in roots, considering them in the context of previous work in plants and animals.
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Affiliation(s)
- Brian G Forde
- Centre for Sustainable Agriculture, Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
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Rouy E, Vico L, Laroche N, Benoit V, Rousseau B, Blachier F, Tomé D, Blais A. Protein quality affects bone status during moderate protein restriction in growing mice. Bone 2014; 59:7-13. [PMID: 24495359 DOI: 10.1016/j.bone.2013.10.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/16/2013] [Accepted: 10/16/2013] [Indexed: 01/16/2023]
Abstract
Adequate protein intake during development is critical to ensure optimal bone gain and to attain a higher peak bone mass later on. We hypothesized that the quality of the dietary protein is of prime importance for bone physiology during moderate protein restriction. The target population was growing Balb/C mice. We compared two protein restricted diets (6% of total energy as protein), one based on soy (LP-SOY) and one based on casein (LP-CAS). For comparison, a normal protein soy-based control group (NP-SOY) and a low protein group receiving an anabolic daily parathyroid hormone (PTH) 1-34 injection (LP-SOY+PTH) were included in the protocol. After 8weeks, LP-SOY mice had reduced body weights related to a lower lean mass whereas LP-CAS mice were not different from the NP-SOY group. LP-SOY mice were characterized by lower femoral cortical thickness, bone volume, trabecular number and thickness and increased medullar adiposity when compared to both the LP-CAS and NP-SOY groups. However, the dietary intervention had no effect on the vertebral parameters. The negative effect of the LP-SOY diet was correlated to an impaired bone formation as shown by the reduced P1NP serum level as well as the reduced osteoid surfaces and bone formation rate in the femur. PTH injection in LP-SOY mice had no effect on total weight or lean mass, but improved all bone parameters at both femoral and vertebral sites, suggesting that amino acid deficiency was not the primary reason for degraded bone status in mice consuming soy protein. In conclusion, our study showed that under the same protein restriction (6% of energy), a soy diet leads to impaired bone health whereas a casein diet has little effect when compared to a normal protein control.
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Affiliation(s)
- Emilien Rouy
- UMR 914 INRA-AgroParisTech, Nutrition Physiology and Ingestive Behavior, 75005 Paris, France; Yoplait France, 92641 Boulogne-Billancourt, France.
| | - Laurence Vico
- INSERM U1059/LBTO, Université Jean Monnet, Université de Lyon, 42023 Saint-Étienne, France
| | - Norbert Laroche
- INSERM U1059/LBTO, Université Jean Monnet, Université de Lyon, 42023 Saint-Étienne, France
| | | | | | - François Blachier
- UMR 914 INRA-AgroParisTech, Nutrition Physiology and Ingestive Behavior, 75005 Paris, France
| | - Daniel Tomé
- UMR 914 INRA-AgroParisTech, Nutrition Physiology and Ingestive Behavior, 75005 Paris, France
| | - Anne Blais
- UMR 914 INRA-AgroParisTech, Nutrition Physiology and Ingestive Behavior, 75005 Paris, France
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Zhang C, Huang Y, Jiang Y, Mulpuri N, Wei L, Hamelberg D, Brown EM, Yang JJ. Identification of an L-phenylalanine binding site enhancing the cooperative responses of the calcium-sensing receptor to calcium. J Biol Chem 2014; 289:5296-309. [PMID: 24394414 DOI: 10.1074/jbc.m113.537357] [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: 12/29/2022] Open
Abstract
Functional positive cooperative activation of the extracellular calcium ([Ca(2+)]o)-sensing receptor (CaSR), a member of the family C G protein-coupled receptors, by [Ca(2+)]o or amino acids elicits intracellular Ca(2+) ([Ca(2+)]i) oscillations. Here, we report the central role of predicted Ca(2+)-binding site 1 within the hinge region of the extracellular domain (ECD) of CaSR and its interaction with other Ca(2+)-binding sites within the ECD in tuning functional positive homotropic cooperativity caused by changes in [Ca(2+)]o. Next, we identify an adjacent L-Phe-binding pocket that is responsible for positive heterotropic cooperativity between [Ca(2+)]o and L-Phe in eliciting CaSR-mediated [Ca(2+)]i oscillations. The heterocommunication between Ca(2+) and an amino acid globally enhances functional positive homotropic cooperative activation of CaSR in response to [Ca(2+)]o signaling by positively impacting multiple [Ca(2+)]o-binding sites within the ECD. Elucidation of the underlying mechanism provides important insights into the longstanding question of how the receptor transduces signals initiated by [Ca(2+)]o and amino acids into intracellular signaling events.
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Affiliation(s)
- Chen Zhang
- From the Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30303 and
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He Y, Perry B, Bi M, Sun H, Zhao T, Li Y, Sun C. Allosteric regulation of the calcium-sensing receptor in obese individuals. Int J Mol Med 2013; 32:511-8. [PMID: 23740560 DOI: 10.3892/ijmm.2013.1408] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 05/24/2013] [Indexed: 11/06/2022] Open
Abstract
We have previously reported that the calcium-sensing receptor (CaSR) plays an important role in modulating lipid metabolism under low calcium conditions. The aim of this study was to identify possible regulators of CaSR and the mechanisms of action of CaSR in obese individuals. Subcutaneous fat samples were obtained from 10 obese and 10 non-obese males undergoing elective abdominal surgery. Visceral fat pads were obtained from 12 obese and 12 non-obese male rats. Serum lipid, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) concentrations, as well as the gene and protein expression of CaSR in the white adipose tissue of obese subjects and rats were determined. Serum total calcium, vitamin D, parathyroid hormone (PTH) and amino acid levels in human subjects were measured. Intracellular calcium and cyclic adenosine monophosphate (cAMP) levels in rat adipocytes were measured by laser scanning confocal microscopy and ELISA, respectively. The results revealed that serum triglyceride (TG), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), TNF-α, IL-6 and PTH levels were significantly higher in the obese individuals versus the controls. By contrast, serum vitamin D and amino acid concentrations were lower in the obese individuals versus the controls. In addition, intracellular calcium levels were higher, while cAMP levels were lower in the obese rat adipocytes compared with the control group. However, the gene and protein expression of CaSR in white adipose tissue did not differ between the obese groups and the controls. Thus, these results suggest that CaSR functions not through its expression, but rather through allosteric regulation in obese individuals.
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Affiliation(s)
- Yonghan He
- National Key Discipline of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
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Invernizzi M, Carda S, Righini V, Baricich A, Cisari C, Bevilacqua M. Different PTH response to oral peptone load and oral calcium load in patients with normocalcemic primary hyperparathyroidism, primary hyperparathyroidism, and healthy subjects. Eur J Endocrinol 2012; 167:491-7. [PMID: 22872468 DOI: 10.1530/eje-12-0362] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Normocalcemic primary hyperparathyroidism (PHPT-N) is a condition that may have similar long-term implications to primary hyperparathyroidism (PHPT); however, differential diagnosis and treatment for parathyroid disorders are not clearly defined. We investigated the effect of an oral peptone and an oral calcium load on calcium-regulating hormones in PHPT-N compared with PHPT and healthy controls to provide a new potential diagnostic tool. DESIGN Case-control study. METHODS We evaluated serum gastrin, PTH, ionized calcium, and phosphate responses to oral calcium (1 g) and peptone (10 g) load in 22 PHPT and 20 PHPT-N patients matched for PTH serum values. Moreover, 30 healthy subjects were enrolled as controls. In 12 patients for each group, we also performed the oral peptone test adding aluminum hydroxide (AH) to suppress phosphate absorption. RESULTS In PHPT patients, PTH increased significantly 30 min after the oral peptone load, while no significant increase was found in PHPT-N and controls. After oral calcium load, PTH remained stable in PHPT while it decreased dramatically in PHPT-N patients, and ionized calcium increased significantly in each of the three groups. Peptones plus AH induced a blunted PTH increase in the three groups. CONCLUSIONS Considering the marked difference in PTH response elicited by peptones in PHPT compared with PHPT-N, we suggest that the oral peptone test could be added to the diagnostic evaluation of PHPT patients. In case of absent response to peptones, patients should have their serum calcium levels assessed twice a year in accordance with recent guidelines.
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Affiliation(s)
- Marco Invernizzi
- Physical and Rehabilitation Medicine, Department of Health Sciences, University of Eastern Piedmont A. Avogadro, AOU Maggiore della Carità, Viale Piazza D'armi 1, 28100 Novara, Italy.
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Vugteveen I, Hoeksma M, Monsen ALB, Fokkema MR, Reijngoud DJ, van Rijn M, van Spronsen FJ. Serum vitamin B12 concentrations within reference values do not exclude functional vitamin B12 deficiency in PKU patients of various ages. Mol Genet Metab 2011; 102:13-7. [PMID: 21030277 DOI: 10.1016/j.ymgme.2010.07.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 07/02/2010] [Accepted: 07/03/2010] [Indexed: 11/28/2022]
Abstract
UNLABELLED Homocysteine (Hcy) and in particular methylmalonic acid (MMA) are considered reliable parameters for vitamin B(12) status in healthy individuals. Phenylketonuria (PKU) patients are at risk for functional vitamin B(12) deficiency based on their diet. OBJECTIVE The aim of this study was to investigate the prevalence of functional vitamin B(12) deficiency in continuously treated PKU patients and the association of parameters of vitamin B(12) and metabolic control. METHODS In 75 continuously treated PKU patients of 1-37 years of age, serum vitamin B(12) concentrations, plasma Hcy, MMA, and phenylalanine concentrations were studied. RESULTS Eight patients had vitamin B(12) concentrations below normal. Out of these eight patients, two had elevated MMA and/or Hcy concentrations. Ten other patients with normal vitamin B(12) concentrations had elevated concentrations of MMA and/or Hcy. CONCLUSIONS A vitamin B(12) concentration within the reference range does not automatically imply a sufficient vitamin B(12) status. We recommend measuring serum MMA, or alternatively plasma Hcy, yearly in all PKU patients to diagnose functional vitamin B(12) deficiency.
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Affiliation(s)
- Inge Vugteveen
- Section of Metabolic Diseases, Beatrix Children's Hospital, University Medical Centre of Groningen, University of Groningen, Groningen, The Netherlands
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Saidak Z, Brazier M, Kamel S, Mentaverri R. Agonists and allosteric modulators of the calcium-sensing receptor and their therapeutic applications. Mol Pharmacol 2009; 76:1131-44. [PMID: 19779033 DOI: 10.1124/mol.109.058784] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The calcium-sensing receptor (CaR) belongs to the G protein-coupled receptor superfamily, with a characteristic structure consisting of seven transmembrane helices, an intracellular C-terminal and an extracellular N terminal domain. The primary physiological function of the CaR is the maintenance of constant blood Ca2+ levels, as a result of its ability to sense very small changes in extracellular Ca2+ (Ca2+(o)). Nevertheless, in addition to being expressed in tissues involved in Ca2+(o) homeostasis, the CaR is also expressed in tissues not involved in mineral homeostasis, suggestive of additional physiological functions. Numerous agonists and modulators of the CaR are now known in addition to Ca2+(o), including various divalent and trivalent cations, aromatic l-amino acids, polyamines, and aminoglycoside antibiotics. The signaling of the CaR is also regulated by extracellular pH and ionic strength. The activated CaR couples mainly to the phospholipase Cbeta and extracellular signal-regulated kinase 1/2 signaling pathways, and it decreases intracellular cAMP levels, leading to various physiological effects. The recent identification of synthetic allosteric modulators of the CaR has opened up a new field of research possibilities. Calcimimetics and calcilytics, which increase and decrease agonist signaling via the CaR, respectively, may facilitate the manipulation of the CaR and thus aid in further investigations of its precise signaling. These allosteric modulators, as well as strontium, have been demonstrated to have therapeutic potential for the treatment of disorders involving the CaR. This review discusses the various agonists and modulators of the CaR, differences in their binding and signaling, and their roles as therapeutics in various diseases.
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Affiliation(s)
- Zuzana Saidak
- INSERM ERI-12, 1, rue des Louvels, Amiens 80037, France.
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Mun HC, Brennan SC, Delbridge L, Wilkinson M, Brown EM, Conigrave AD. Adenomatous human parathyroid cells exhibit impaired sensitivity to L-amino acids. J Clin Endocrinol Metab 2009; 94:3567-74. [PMID: 19567535 PMCID: PMC2741716 DOI: 10.1210/jc.2008-2714] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Primary hyperparathyroidism, which occurs most commonly in patients with adenomatous disease of a single parathyroid gland, arises as a result of impaired extracellular Ca(2+) (Ca(2+)(o))-dependent feedback on PTH secretion, a process mediated by the calcium-sensing receptor (CaR). OBJECTIVE Because the Ca(2+)(o) sensitivity of the CaR is positively modulated by L-amino acids, we decided to investigate whether the impaired feedback of PTH secretion in adenomatous parathyroid cells might arise from decreased sensitivity to L-amino acids. DESIGN Samples of normal and adenomatous human parathyroid cells were prepared by collagenase treatment and then exposed in vitro to various concentrations of Ca(2+)(o) or the CaR-active amino acid, L-phenylalanine (L-Phe). SETTING AND PATIENTS Excess normal parathyroid tissue was obtained from parathyroid autotransplants at the time of thyroid surgery. Samples of adenomatous tissue were obtained from histologically confirmed parathyroid adenomas. MAIN OUTCOME MEASURES The primary measure was sensitivity of Ca(2+)(o)-dependent PTH secretion to the amino acid L-Phe. The secondary measure was sensitivity of Ca(2+)(o)-dependent intracellular Ca(2+) mobilization to L-Phe. RESULTS Parathyroid adenomas exhibited reduced sensitivity to the CaR-active amino acid L-Phe, which affected both Ca(2+)(o)-dependent PTH secretion and Ca(2+)(o)-dependent intracellular Ca(2+) mobilization as a measure of CaR-dependent signaling in parathyroid cells. CONCLUSIONS Impaired L-amino acid sensing by calcium-sensing receptors in adenomatous parathyroid cells contributes to the loss of feedback control of PTH secretion in primary hyperparathyroidism. The CaR's amino acid binding site may be exploited as a target in the medical treatment of primary and perhaps other forms of hyperparathyroidism.
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Affiliation(s)
- H-C Mun
- School of Molecular and Microbial Biosciences, University of Sydney, New South Wales 2006, Australia
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Geibel JP, Hebert SC. The Functions and Roles of the Extracellular Ca2+–Sensing Receptor along the Gastrointestinal Tract. Annu Rev Physiol 2009; 71:205-17. [DOI: 10.1146/annurev.physiol.010908.163128] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- John P. Geibel
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06520;
| | - Steven C. Hebert
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520
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