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Qi L, Zhang H, Guo Y, Zhang C, Xu Y. A novel calcium-binding peptide from bovine bone collagen hydrolysate and chelation mechanism and calcium absorption activity of peptide-calcium chelate. Food Chem 2023; 410:135387. [PMID: 36621334 DOI: 10.1016/j.foodchem.2023.135387] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 12/11/2022] [Accepted: 01/02/2023] [Indexed: 01/05/2023]
Abstract
A novel calcium-binding peptide from bovine bone collagen hydrolysate was screened based on a new target-the calcium-sensing receptor (CaSR), and its chelation mechanism and calcium absorption activity were investigated. Glu-Tyr-Gly exhibited superior binding affinities to CaSR because of its interaction with the active sites of the CaSR Venus Flytrap (VFT) domain. Glu-Tyr-Gly-Ca may exist in five potential chelation modes and its potential chelation mechanism was that calcium ions were located in the center and surrounded by ionic bonds (carboxyl group) and coordination bonds (carbonyl, amino, and carboxyl group). Glu-Tyr-Gly-Ca was slightly damaged in the intestinal fluid and at different temperatures, whereas it was severely damaged in the gastric fluid and acidic conditions. The results of the calcium dialysis percentage and Caco-2 cells experiments showed that Glu-Tyr-Gly-Ca possessed good calcium transport activity and bioavailability. The findings provided theoretical basis for Glu-Tyr-Gly-Ca as potential calcium supplement to improve intestinal calcium absorption.
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Affiliation(s)
- Liwei Qi
- Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Hongru Zhang
- Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China; Laboratory of Biomass and Green Technologies, University of Liege-Gembloux Agro-Bio Tech, Passage des déportés 2, B-5030 Gembloux, Belgium
| | - Yujie Guo
- Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Chunhui Zhang
- Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Yang Xu
- Inner Mongolia Mengtai Biological Engineering Co., Ltd, Shengle Economic Park, Helinger County, Hohhot, Inner Mongolia 010000, China
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Nikolovska K, Cao L, Hensel I, Di Stefano G, Seidler A, Zhou K, Qian J, Singh AK, Riederer B, Seidler U. Sodium/hydrogen-exchanger-2 modulates colonocyte lineage differentiation. Acta Physiol (Oxf) 2022; 234:e13774. [PMID: 34985202 DOI: 10.1111/apha.13774] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/12/2021] [Accepted: 01/01/2022] [Indexed: 12/11/2022]
Abstract
AIM The sodium/hydrogen exchanger 2 (NHE2) is an intestinal acid extruder with crypt-predominant localization and unresolved physiological significance. Our aim was to decipher its role in colonic epithelial cell proliferation, differentiation and electrolyte transport. METHODS Alterations induced by NHE2-deficiency were addressed in murine nhe2-/- and nhe2+/+ colonic crypts and colonoids, and NHE2-knockdown and control Caco2Bbe cells using pH-fluorometry, gene expression analysis and immunofluorescence. RESULTS pHi -measurements along the colonic cryptal axis revealed significantly decreased intracellular pH (pHi ) in the middle segment of nhe2-/- compared to nhe2+/+ crypts. Increased Nhe2 mRNA expression was detected in murine colonoids in the transiently amplifying/progenitor cell stage (TA/PE). Lack of Nhe2 altered the differentiation programme of colonic epithelial cells with reduced expression of absorptive lineage markers alkaline phosphatase (iAlp), Slc26a3 and transcription factor hairy and enhancer-of-split 1 (Hes1), but increased expression of secretory lineage markers Mucin 2, trefoil factor 3 (Tff3), enteroendocrine marker chromogranin A and murine atonal homolog 1 (Math1). Enterocyte differentiation was found to be pHi dependent with acidic pHi reducing, and alkaline pHi stimulating the expression of enterocyte differentiation markers in Caco2Bbe cells. A thicker mucus layer, longer crypts and an expanded brush border membrane zone of sodium/hydrogen exchanger 3 (NHE3) abundance may explain the lack of inflammation and the normal fluid absorptive rate in nhe2-/- colon. CONCLUSIONS The results suggest that NHE2 expression is activated when colonocytes emerge from the stem cell niche. Its activity increases progenitor cell pHi and thereby supports absorptive enterocyte differentiation.
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Affiliation(s)
- Katerina Nikolovska
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
| | - Li Cao
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
- Department of Gastroenterology Tongji Hospital Huazhong University Wuhan China
| | - Inga Hensel
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
| | - Gabriella Di Stefano
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
| | - Anna Elisabeth Seidler
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
| | - Kunyan Zhou
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
| | - Jiajie Qian
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
- Department of Transplantation and Hepatobiliary Surgery First Affiliated Hospital of Zheijang University Hangzhou China
| | - Anurag Kumar Singh
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
- Department of Physiological Chemistry University of Halle Halle (Saale) Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and Endocrinology Hannover Medical School Hannover Germany
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Li X, Chen S, Feng D, Fu Y, Wu H, Lu J, Bao J. Calcium-sensing receptor promotes calcium oxalate crystal adhesion and renal injury in Wistar rats by promoting ROS production and subsequent regulation of PS ectropion, OPN, KIM-1, and ERK expression. Ren Fail 2021; 43:465-476. [PMID: 33678127 PMCID: PMC7946014 DOI: 10.1080/0886022x.2021.1881554] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES To explore the mechanism of calcium-sensing receptors (CaSRs) during the development of nephrolithiasis. MATERIALS AND METHODS Wistar rats were treated with ethylene glycol to induce calcium oxalate crystallization, and gadolinium chloride (GdCl3, an agonist of CaSR) and NPS 2390 (an antagonist of CaSR) were added. Oxidative stress (OS) and calcium oxalate crystals in the kidney were observed. CaSR expression and the expression of extracellular signal-regulated protein kinase (ERK), OPN, and KIM-1 were determined by western blotting. In addition, renal tubular epithelial cells were isolated from the kidney to observe phosphatidylserine (PS) ectropion using flow cytometric analysis. Various biochemical parameters were assessed in serum and urine at the end of the experiment. RESULTS Calcium oxalate increased OS, crystal adhesion, PS ectropion, and the expression of CaSR and ERK, OPN, and KIM-1 in vivo. In addition, lower levels of urine citrate as well as increased serum creatinine and urea levels were observed after treatment with calcium oxalate (p < .05). Compared with calcium oxalate treatment alone, the above deleterious changes were further significantly confirmed by GdCl3 but were reversed by NPS-2390. However, urine calcium excretion was decreased after ethylene glycol treatment but was significantly reduced by NPS 2390 and increased by GdCl3 (p < .05). CONCLUSIONS The results suggest that CaSR might play significant roles in the induction of nephrolithiasis in rats by regulating reactive oxygen species (ROS) and PS ectropion and the composition of urine, OPN, KIM-1, and ERK expression.
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Affiliation(s)
- Xiaoran Li
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
| | - Siyu Chen
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
| | - Demei Feng
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
| | - Yuqiang Fu
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
| | - Huang Wu
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
| | - Jianzhong Lu
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
| | - Junsheng Bao
- Department of Urology, Institute of Urology, Gansu Nephro-Urological Clinical Center, Key Laboratory of Urological Diseases in Gansu Province, Lanzhou University Second Hospital, Lanzhou, People's Republic of China
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Michiels M, Daleo G, López Mañanes A. Differential modulation after feeding in different salinities and response to abscisic acid (ABA) and extracellular Ca 2+ of aminopeptidase N (APN) activity in the hepatopancreas of the intertidal euryhaline crab Neohelice granulata. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Modulation of aminopeptidase N (APN) activity in the digestive tract by various factors would be important to adjust digestive and absorptive processes under different physiological and (or) environmental conditions. We studied the postprandial responses at different salinities and the effect of abscisic acid (ABA) and extracellular Ca2+ on APN activity in the hepatopancreas (the main site for nutrient digestion and absorption) of the model species Neohelice granulata (Dana, 1851). Enzyme activity was determined at different times (0, 24, 48, and 72 h) after feeding in crabs acclimated either to 35 psu (osmoconformation) or 10 psu (hyper-regulation). APN activity increased around 50% at 24 h after feeding at 35 psu, whereas no changes occurred at 10 psu. Enzyme activity was also assayed in the presence of ABA (1 × 10–4 mol·L–1) or extracellular Ca2+ (1 × 10–4 mol·L–1), showing increments of 60% and 56%, respectively. The results suggest a role of APN in postprandial adjustments and its modulation by different chemical messengers by direct effect on the hepatopancreas. Moreover, to our knowledge, this work is the first to show the effect of ABA on a digestive enzyme in the digestive tract of an animal.
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Affiliation(s)
- M.S. Michiels
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Funes 3250, Mar del Plata, Argentina
| | - G.R. Daleo
- Instituto de Investigaciones Biológicas (IIB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del, Plata, Argentina
| | - A.A. López Mañanes
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Funes 3250, Mar del Plata, Argentina
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Xu J, Zeug A, Riederer B, Yeruva S, Griesbeck O, Daniel H, Tuo B, Ponimaskin E, Dong H, Seidler U. Calcium-sensing receptor regulates intestinal dipeptide absorption via Ca 2+ signaling and IK Ca activation. Physiol Rep 2020; 8:e14337. [PMID: 31960592 PMCID: PMC6971415 DOI: 10.14814/phy2.14337] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although absorption of di- and tripeptides into intestinal epithelial cells occurs via the peptide transporter 1 (PEPT1, also called solute carrier family 15 member 1 (SLC15A1)), the detailed regulatory mechanisms are not fully understood. We examined: (a) whether dipeptide absorption in villous enterocytes is associated with a rise in cytosolic Ca2+ ([Ca2+ ]cyt ), (b) whether the calcium sensing receptor (CaSR) is involved in dipeptide-elicited [Ca2+ ]cyt signaling, and (c) what potential consequences of [Ca2+ ]cyt signaling may enhance enterocyte dipeptide absorption. Dipeptide Gly-Sar and CaSR agonist spermine markedly raised [Ca2+ ]cyt in villous enterocytes, which was abolished by NPS-2143, a selective CaSR antagonist and U73122, an phospholipase C (PLC) inhibitor. Apical application of Gly-Sar induced a jejunal short-circuit current (Isc), which was reduced by NPS-2143. CaSR expression was identified in the lamina propria and on the basal enterocyte membrane of mouse jejunal mucosa in both WT and Slc15a1-/- animals, but Gly-Sar-induced [Ca2+ ]cyt signaling was significantly decreased in Slc15a1-/- villi. Clotrimazole and TRM-34, two selective blockers of the intermediate conductance Ca2+ -activated K+ channel (IKCa ), but not iberiotoxin, a selective blocker of the large-conductance K+ channel (BKCa ) and apamin, a selective blocker of the small-conductance K+ channel (SKCa ), significantly inhibited Gly-Sar-induced Isc in native tissues. We reveal a novel CaSR-PLC-Ca2+ -IKCa pathway in the regulation of small intestinal dipeptide absorption, which may be exploited as a target for future drug development in human nutritional disorders.
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Affiliation(s)
- Jingyu Xu
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Andre Zeug
- Cellular NeurophysiologyHannover Medical SchoolHannoverGermany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | - Sunil Yeruva
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | | | - Hannelore Daniel
- Nutritional PhysiologyTechnical University of MunichFreisingGermany
| | - Biguang Tuo
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | | | - Hui Dong
- Department of MedicineUniversity of California, San DiegoLa JollaCAUSA
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
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6
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Glutaminase-catalyzed γ-glutamylation to produce CCK secretion-stimulatory γ-[Glu]n-Trp peptides superior to tryptophan. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.103418] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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7
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Gamma glutamyl peptides: The food source, enzymatic synthesis, kokumi-active and the potential functional properties – A review. Trends Food Sci Technol 2019. [DOI: 10.1016/j.tifs.2019.07.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Barahona MJ, Maina RM, Lysyy T, Finotti M, Caturegli G, Baratta V, D'Amico F, Mulligan D, Geibel JP. Activation of the Calcium Sensing Receptor Decreases Secretagogue-Induced Fluid Secretion in the Rat Small Intestine. Front Physiol 2019; 10:439. [PMID: 31130866 PMCID: PMC6509940 DOI: 10.3389/fphys.2019.00439] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 04/01/2019] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The calcium-sensing receptor (CaSR) has been localized and characterized in numerous tissues throughout the body. In the mammalian gastrointestinal tract, the CaSR is known to act as a nutrient sensor and has recently been found to play a role in intestinal fluid and electrolyte balance. This study aims to demonstrate the functionality of the CaSR as a modulator of fluid secretion and absorption along the small intestine. METHODS Small intestine regions (proximal, middle, and distal) were isolated from Sprague Dawley rats and loaded into an ex vivo intestinal perfusion device that provides independent intraluminal and extraluminal (serosa/basolateral) perfusion. The regions were perfused with 5 and 7 mM of Ca2+, both in the presence and absence of forskolin (FSK), a potent secretagogue. Control experiments were conducted with intraluminal perfusate containing standard Ringer-HEPES buffer with a physiological concentration of Ca2+ (1 mM). A second set of comparison experiments was performed with intraluminal perfusates containing AC-265347, a CaSR activator and agonist, in the presence of FSK. In all experimental conditions, the intraluminal perfusate contained fluorescein isothiocyanate (FITC)-inulin, a nonabsorbable fluorescent marker of secretion and/or absorption. Intraluminal fluorescence signal was utilized as a measure of water movement at the start of the experiment and every 15 min for 90 min. RESULTS Under physiological conditions, increasing the concentration of Ca2+ in the luminal perfusate reduced intestinal fluid secretion in all regions. At a Ca2+ concentration of 7 mM, net fluid absorption was observed in all regions. In the presence of FSK, 5 mM Ca2+ significantly decreased fluid secretion and 7 mM Ca2+ abolished FSK-induced fluid secretion. Intraluminal perfusion with 5 mM Ca2+ was as effective as AC-265347, in reducing secretagogue-induced fluid hypersecretion in the proximal and middle regions. CONCLUSION This study concludes that apical CaSR is active along the small intestine. Its activation by Ca2+ and/or calcimimetics reduces fluid secretion in a dose-dependent manner, with higher Ca2+ concentrations, or application of a calcimimetic, leading to fluid absorption. We furthermore show that, in the presence of FSK, receptor activation abates FSK secretagogue-induced fluid secretion. This presents a new therapeutic target to address secretory diarrheal illnesses.
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Affiliation(s)
- Maria J Barahona
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
| | - Renee M Maina
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
| | - Taras Lysyy
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
| | - Michele Finotti
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States.,Transplantation and Hepatobiliary Surgery, University of Padua, Padua, Italy
| | - Giorgio Caturegli
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
| | - Vanessa Baratta
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
| | - Francesco D'Amico
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States.,Transplantation and Hepatobiliary Surgery, University of Padua, Padua, Italy
| | - David Mulligan
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
| | - John P Geibel
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States
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Yang J, Bai W, Zeng X, Cui C. γ-[Glu](n=1,2)-Phe/-Met/-Val stimulates gastrointestinal hormone (CCK and GLP-1) secretion by activating the calcium-sensing receptor. Food Funct 2019; 10:4071-4080. [DOI: 10.1039/c9fo00313d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This study was conducted to discover the effectiveness of dietary peptides (γ-[Glu](n=1,2)-Phe/-Met/-Val) as stimulators of cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) secretion.
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Affiliation(s)
- Juan Yang
- College of Food Science and Technology
- Zhongkai University of Agriculture and Engineering
- Guangzhou
- China
| | - Weidong Bai
- College of Food Science and Technology
- Zhongkai University of Agriculture and Engineering
- Guangzhou
- China
| | - Xiaofang Zeng
- College of Food Science and Technology
- Zhongkai University of Agriculture and Engineering
- Guangzhou
- China
| | - Chun Cui
- School of Food Science and Engineering
- South China University of Technology
- Guangzhou 510640
- China
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10
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Hannan FM, Kallay E, Chang W, Brandi ML, Thakker RV. The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases. Nat Rev Endocrinol 2018; 15:33-51. [PMID: 30443043 PMCID: PMC6535143 DOI: 10.1038/s41574-018-0115-0] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Ca2+-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca2+ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca2+ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.
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Affiliation(s)
- Fadil M Hannan
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Enikö Kallay
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Wenhan Chang
- Endocrine Research Unit, Veterans Affairs Medical Center, University of California, San Francisco, San Francisco, CA, USA
| | - Maria Luisa Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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11
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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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12
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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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Calcium-sensing receptor in nutrient sensing: an insight into the modulation of intestinal homoeostasis. Br J Nutr 2018; 120:881-890. [DOI: 10.1017/s0007114518002088] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AbstractThe animal gut effectively prevents the entry of hazardous substances and microbes while permitting the transfer of nutrients, such as water, electrolytes, vitamins, proteins, lipids, carbohydrates, minerals and microbial metabolites, which are intimately associated with intestinal homoeostasis. The gut maintains biological functions through its nutrient-sensing receptors, including the Ca-sensing receptor (CaSR), which activates a variety of signalling pathways, depending on cellular context. CaSR coordinates food digestion and nutrient absorption, promotes cell proliferation and differentiation, regulates energy metabolism and immune response, stimulates hormone secretion, mitigates secretory diarrhoea and enhances intestinal barrier function. Thus, CaSR is crucial to the maintenance of gut homoeostasis and protection of intestinal health. In this review, we focused on the emerging roles of CaSR in the modulation of intestinal homoeostasis including related underlying mechanisms. By elucidating the relationship between CaSR and animal gut homoeostasis, effective and inexpensive methods for treating intestinal health imbalance through nutritional manipulation can be developed. This article is expected to provide experimental data of the effects of CaSR on animal or human health.
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Functions and Signaling Pathways of Amino Acids in Intestinal Inflammation. BIOMED RESEARCH INTERNATIONAL 2018; 2018:9171905. [PMID: 29682569 PMCID: PMC5846438 DOI: 10.1155/2018/9171905] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/30/2017] [Accepted: 12/13/2017] [Indexed: 12/11/2022]
Abstract
Intestine is always exposed to external environment and intestinal microorganism; thus it is more sensitive to dysfunction and dysbiosis, leading to intestinal inflammation, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and diarrhea. An increasing number of studies indicate that dietary amino acids play significant roles in preventing and treating intestinal inflammation. The review aims to summarize the functions and signaling mechanisms of amino acids in intestinal inflammation. Amino acids, including essential amino acids (EAAs), conditionally essential amino acids (CEAAs), and nonessential amino acids (NEAAs), improve the functions of intestinal barrier and expressions of anti-inflammatory cytokines and tight junction proteins but decrease oxidative stress and the apoptosis of enterocytes as well as the expressions of proinflammatory cytokines in the intestinal inflammation. The functions of amino acids are associated with various signaling pathways, including mechanistic target of rapamycin (mTOR), inducible nitric oxide synthase (iNOS), calcium-sensing receptor (CaSR), nuclear factor-kappa-B (NF-κB), mitogen-activated protein kinase (MAPK), nuclear erythroid-related factor 2 (Nrf2), general controlled nonrepressed kinase 2 (GCN2), and angiotensin-converting enzyme 2 (ACE2).
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15
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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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Pfanzagl B, Mechtcheriakova D, Meshcheryakova A, Aberle SW, Pfragner R, Jensen-Jarolim E. Activation of the ileal neuroendocrine tumor cell line P-STS by acetylcholine is amplified by histamine: role of H3R and H4R. Sci Rep 2017; 7:1313. [PMID: 28465562 PMCID: PMC5430954 DOI: 10.1038/s41598-017-01453-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 03/30/2017] [Indexed: 12/13/2022] Open
Abstract
Neuroendocrine tumors may present with pseudoallergic reactions like diarrhea and idiopathic anaphylaxis. Here we present the P-STS human ileal neuroendocrine cell line as a model cell line for these tumors. Neuroendocrine markers and changes in cytoplasmic calcium concentration ([Ca2+]i) in response to several possible activators of 5-hydroxytryptamine (5-HT) release were analyzed. P-STS cells still expressed chromogranin A and synaptophysin after 2 years of culture. Tryptophan hydroxylase 1 mRNA and a low amount of 5-HT were also detected. Acetylcholine (ACh) caused a rise in [Ca2+]i. Somatostatin inhibited, whereas histamine (HA) but not the HA receptor ligand betahistine enhanced activation by ACh. The [Ca2+]i response to ACh/HA was inhibited by the HA receptor H3 (H3R) agonist methimepip and by the antidepressant imipramine. Further [Ca2+]i response studies indicated the presence of H4Rs and of a functional calcium sensing receptor. High or low affinity IgE receptor protein or mRNA were not detected. Taken together, neuroendocrine markers and response to intestinal neurotransmitters approve the P-STS cell line as a valuable model for enterochromaffin cells. Enhancement of their ACh-induced pro-secretory response by HA, with a role for H3R and H4R, suggests an amplifying role of neuroendocrine cells in allergen-induced diarrhea or anaphylaxis.
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Affiliation(s)
- Beatrix Pfanzagl
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, 1090, Austria.
| | - Diana Mechtcheriakova
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, 1090, Austria
| | - Anastasia Meshcheryakova
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, 1090, Austria
| | - Stephan W Aberle
- Department of Virology, Medical University of Vienna, Vienna, 1090, Austria
| | - Roswitha Pfragner
- Department of Pathophysiology and Immunology, Center of Molecular Medicine, Medical University of Graz, Graz, 8010, Austria
| | - Erika Jensen-Jarolim
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, 1090, Austria.
- The interuniversity Messerli Research Institute, University of Veterinary Medicine Vienna, Medical University Vienna, University Vienna, Vienna, 1210, Austria.
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17
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Hernández-Bedolla MA, González-Domínguez E, Zavala-Barrera C, Gutiérrez-López TY, Hidalgo-Moyle JJ, Vázquez-Prado J, Sánchez-Torres C, Reyes-Cruz G. Calcium-sensing-receptor (CaSR) controls IL-6 secretion in metastatic breast cancer MDA-MB-231 cells by a dual mechanism revealed by agonist and inverse-agonist modulators. Mol Cell Endocrinol 2016; 436:159-68. [PMID: 27477783 DOI: 10.1016/j.mce.2016.07.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/27/2016] [Accepted: 07/27/2016] [Indexed: 01/25/2023]
Abstract
IL-6 is a tightly controlled pleiotropic cytokine with hormone-like properties whose levels are frequently altered in cancer and inflammatory diseases. In highly invasive MDA-MB-231 breast cancer cells, basal activity of endogenously expressed calcium sensing receptor (CaSR) promotes IL-6 secretion. Interestingly, upon agonist stimulation, CaSR reduces IL-6 levels whereas it promotes secretion of various other cytokines and growth factors, raising intriguing questions about how CaSR signaling modulates IL-6 secretion. Here, using NPS-2143, which acted as an inverse agonist, we show that IL-6 secretion promoted by constitutive activity of CaSR is mechanistically linked to Gαs/PKC, MEK1/2 and mTORC1 signaling pathways, integrated by transactivated EGFR. On the other hand, agonist-stimulated CaSR engages in a Rab11a-dependent trafficking pathway critical to inhibit constitutive IL-6 secretion via the PI3K/AKT and PKC signaling pathways. These results support the emerging potential of CaSR as a therapeutic target in metastatic breast cancer whose pharmacological modulation would reduce IL-6.
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Affiliation(s)
- Marco Antonio Hernández-Bedolla
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Erika González-Domínguez
- Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Cesar Zavala-Barrera
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Tania Yareli Gutiérrez-López
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Joseline Janai Hidalgo-Moyle
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - José Vázquez-Prado
- Department of Pharmacology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Carmen Sánchez-Torres
- Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Guadalupe Reyes-Cruz
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico.
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18
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Aggarwal A, Kállay E. Cross Talk between the Calcium-Sensing Receptor and the Vitamin D System in Prevention of Cancer. Front Physiol 2016; 7:451. [PMID: 27803671 PMCID: PMC5067519 DOI: 10.3389/fphys.2016.00451] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/21/2016] [Indexed: 12/25/2022] Open
Abstract
There is epidemiological evidence for the cancer preventive effect of dietary calcium (Ca2+) and vitamin D. This effect is strongest in colorectal cancer (CRC). The active vitamin D metabolite, 1,25-dihydroxyvitamin D3 (1,25D3), bound to its receptor, the vitamin D receptor (VDR) regulates the expression of hundreds of different genes in a cell- and tissue-specific manner. While Ca2+ acts through multiple mechanisms and pathways, some of its effects are mediated by the calcium-sensing receptor (CaSR). The joint action of Ca2+ and 1,25D3 is due to the fact that both regulate some of the main processes involved in the development of various cancers, such as proliferation, differentiation, apoptosis, migration, and inflammation. Moreover, 1,25D3, bound to VDR can induce translation of the CaSR, while the amount and activity of the CaSR affects 1,25D3 signaling. However, the complexity of the cross-talk between the CaSR and the vitamin D system goes beyond regulating similar pathways and affecting each other's expression. Our aim was to review some of the mechanisms that drive the cross-talk between the vitamin D system and the CaSR with a special focus on the interaction in CRC cells. We evaluated the molecular evidence that supports the epidemiological observation that both vitamin D and calcium are needed for protection against malignant transformation of the colon and that their effect is modulated by the presence of a functional CaSR.
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Affiliation(s)
- Abhishek Aggarwal
- Department of Pathophysiology and Allergy Research, Center of Pathophysiology, Infectiology and Immunology, Medical University of ViennaVienna, Austria; Department of Pediatrics/Endocrinology, School of Medicine, Stanford UniversityStanford, CA, USA
| | - Enikö Kállay
- Department of Pathophysiology and Allergy Research, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna Vienna, Austria
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19
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Mayr B, Glaudo M, Schöfl C. Activating Calcium-Sensing Receptor Mutations: Prospects for Future Treatment with Calcilytics. Trends Endocrinol Metab 2016; 27:643-652. [PMID: 27339034 DOI: 10.1016/j.tem.2016.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/17/2016] [Accepted: 05/20/2016] [Indexed: 12/20/2022]
Abstract
Activating mutations of the G protein-coupled receptor, calcium-sensing receptor (CaSR), cause autosomal dominant hypocalcemia and Bartter syndrome type 5. These mutations lower the set-point for extracellular calcium sensing, thereby causing decreased parathyroid hormone secretion and disturbed renal calcium handling with hypercalciuria. Available therapies increase serum calcium levels but raise the risk of complications in affected patients. Symptom relief and the prevention of adverse outcome is currently very difficult to achieve. Calcilytics act as CaSR antagonists that attenuate its activity, thereby correcting the molecular defect of activating CaSR proteins in vitro and elevating serum calcium in mice and humans in vivo, and have emerged as the most promising therapeutics for the treatment of these rare and difficult to treat diseases.
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Affiliation(s)
- Bernhard Mayr
- Division of Endocrinology and Diabetes, Department of Medicine I, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Germany.
| | - Markus Glaudo
- Division of Endocrinology and Diabetes, Department of Medicine I, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Germany
| | - Christof Schöfl
- Division of Endocrinology and Diabetes, Department of Medicine I, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Germany
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20
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Ellinger I. The Calcium-Sensing Receptor and the Reproductive System. Front Physiol 2016; 7:371. [PMID: 27625611 PMCID: PMC5003915 DOI: 10.3389/fphys.2016.00371] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/11/2016] [Indexed: 12/14/2022] Open
Abstract
Active placental transport of maternal serum calcium (Ca2+) to the offspring is pivotal for proper development of the fetal skeleton as well as various organ systems. Moreover, extracellular Ca2+ levels impact on distinct processes in mammalian reproduction. The calcium-sensing receptor (CaSR) translates changes in extracellular Ca2+-concentrations into cellular reactions. This review summarizes current knowledge on the expression of CaSR and its putative functions in reproductive organs. CaSR was detected in placental cells mediating materno-fetal Ca2+-transport such as the murine intraplacental yolk sac (IPYS) and the human syncytiotrophoblast. As shown in casr knock-out mice, ablation of CaSR downregulates transplacental Ca2+-transport. Receptor expression was reported in human and rat ovarian surface epithelial (ROSE) cells, where CaSR activation stimulates cell proliferation. In follicles of various species a role of CaSR activation in oocyte maturation was suggested. Based on studies in avian follicles, the activation of CaSR expressed in granulosa cells may support the survival of follicles after their selection. CaSR in rat and equine sperms was functionally linked to sperm motility and sperm capacitation. Implantation involves complex interactions between the blastocyst and the uterine epithelium. During early pregnancy, CaSR expression at the implantation site as well as in decidual cells indicates that CaSR is important for blastocyst implantation and decidualization in the rat uterus. Localization of CaSR in human extravillous cytotrophoblasts suggests a role of CaSR in placentation. Overall, evidence for functional involvement of CaSR in physiologic mammalian reproductive processes exists. Moreover, several studies reported altered expression of CaSR in cells of reproductive tissues under pathologic conditions. However, in many tissues we still lack knowledge on physiological ligands activating CaSR, CaSR-linked G-proteins, activated intracellular signaling pathway, and functional relevance of CaSR activation. Clearly, more work is required in the future to decode the complex physiologic and pathophysiologic relationship of CaSR and the mammalian reproductive system.
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Affiliation(s)
- Isabella Ellinger
- Pathophysiology of the Placenta, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University Vienna Vienna, Austria
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21
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Nakajima S, Hira T, Iwaya H, Hara H. Zinc directly stimulates cholecystokinin secretion from enteroendocrine cells and reduces gastric emptying in rats. Mol Cell Endocrinol 2016; 430:108-14. [PMID: 27107934 DOI: 10.1016/j.mce.2016.04.010] [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: 01/07/2016] [Revised: 04/06/2016] [Accepted: 04/19/2016] [Indexed: 12/27/2022]
Abstract
Zinc, an essential mineral element, regulates various physiological functions such as immune responses and hormone secretion. Cholecystokinin (CCK), a gut hormone, has a role in protective immunity through the regulation of gastrointestinal motility, appetite, and inflammatory response. Here, we examined the effect of zinc on CCK secretion in STC-1 cells, an enteroendocrine cell line derived from murine duodenum, and in rats. Extracellular zinc triggered CCK secretion accompanied with increased intracellular Ca(2+) and Zn(2+) mobilization in STC-1 cells. Zinc-induced CCK secretion was abolished in the absence of intracellular Zn(2+) or extracellular calcium. Upon inhibition of transient receptor potential ankyrin 1 (TRPA1), extracellular zinc failed to increase intracellular Ca(2+) and subsequent CCK secretion. In rats, oral zinc administration decreased gastric emptying through the activation of CCK signaling. These results suggest that zinc is a novel stimulant for CCK secretion through the activation of TRPA1 related to intracellular Zn(2+) and Ca(2+) mobilization.
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Affiliation(s)
- Shingo Nakajima
- Research Faculty of Health Science, Hokkaido University, Japan; Research Faculty of Agriculture, Hokkaido University, Japan
| | - Tohru Hira
- Research Faculty of Agriculture, Hokkaido University, Japan.
| | - Hitoshi Iwaya
- Research Faculty of Agriculture, Hokkaido University, Japan; La Jolla Institute for Allergy & Immunology, USA
| | - Hiroshi Hara
- Research Faculty of Agriculture, Hokkaido University, Japan
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22
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Tang L, Cheng CY, Sun X, Pedicone AJ, Mohamadzadeh M, Cheng SX. The Extracellular Calcium-Sensing Receptor in the Intestine: Evidence for Regulation of Colonic Absorption, Secretion, Motility, and Immunity. Front Physiol 2016; 7:245. [PMID: 27458380 PMCID: PMC4914593 DOI: 10.3389/fphys.2016.00245] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 06/03/2016] [Indexed: 12/14/2022] Open
Abstract
Different from other epithelia, the intestinal epithelium has the complex task of providing a barrier impeding the entry of toxins, food antigens, and microbes, while at the same time allowing for the transfer of nutrients, electrolytes, water, and microbial metabolites. These molecules/organisms are transported either transcellularly, crossing the apical and basolateral membranes of enterocytes, or paracellularly, passing through the space between enterocytes. Accordingly, the intestinal epithelium can affect energy metabolism, fluid balance, as well as immune response and tolerance. To help accomplish these complex tasks, the intestinal epithelium has evolved many sensing receptor mechanisms. Yet, their roles and functions are only now beginning to be elucidated. This article explores one such sensing receptor mechanism, carried out by the extracellular calcium-sensing receptor (CaSR). In addition to its established function as a nutrient sensor, coordinating food digestion, nutrient absorption, and regulating energy metabolism, we present evidence for the emerging role of CaSR in the control of intestinal fluid homeostasis and immune balance. An additional role in the modulation of the enteric nerve activity and motility is also discussed. Clearly, CaSR has profound effects on many aspects of intestinal function. Nevertheless, more work is needed to fully understand all functions of CaSR in the intestine, including detailed mechanisms of action and specific pathways involved. Considering the essential roles CaSR plays in gastrointestinal physiology and immunology, research may lead to a translational opportunity for the development of novel therapies that are based on CaSR's unique property of using simple nutrients such as calcium, polyamines, and certain amino acids/oligopeptides as activators. It is possible that, through targeting of intestinal CaSR with a combination of specific nutrients, oral solutions that are both inexpensive and practical may be developed to help in conditioning the gut microenvironment and in maintaining digestive health.
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Affiliation(s)
- Lieqi Tang
- Department of Pediatrics, Gastroenterology, Hepatology, and Nutrition, University of Florida Gainesville, FL, USA
| | - Catherine Y Cheng
- Department of Pediatrics, Gastroenterology, Hepatology, and Nutrition, University of Florida Gainesville, FL, USA
| | - Xiangrong Sun
- Department of Pediatrics, Gastroenterology, Hepatology, and Nutrition, University of Florida Gainesville, FL, USA
| | - Alexandra J Pedicone
- Department of Pediatrics, Gastroenterology, Hepatology, and Nutrition, University of Florida Gainesville, FL, USA
| | - Mansour Mohamadzadeh
- Department of Medicine, Center for Inflammation and Mucosal Immunology, University of Florida Gainesville, FL, USA
| | - Sam X Cheng
- Department of Pediatrics, Gastroenterology, Hepatology, and Nutrition, University of Florida Gainesville, FL, USA
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Latorre R, Sternini C, De Giorgio R, Greenwood-Van Meerveld B. Enteroendocrine cells: a review of their role in brain-gut communication. Neurogastroenterol Motil 2016; 28:620-30. [PMID: 26691223 PMCID: PMC4842178 DOI: 10.1111/nmo.12754] [Citation(s) in RCA: 200] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 11/17/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND Specialized endoderm-derived epithelial cells, that is, enteroendocrine cells (EECs), are widely distributed throughout the gastrointestinal (GI) tract. Enteroendocrine cells form the largest endocrine organ in the body and play a key role in the control of GI secretion and motility, the regulation of food intake, postprandial glucose levels and metabolism. EECs sense luminal content and release signaling molecules that can enter the circulation to act as classic hormones on distant targets, act locally on neighboring cells and on distinct neuronal pathways including enteric and extrinsic neurons. Recent studies have shed light on EEC sensory transmission by showing direct connections between EECs and the nervous system via axon-like processes that form a well-defined neuroepithelial circuits through which EECs can directly communicate with the neurons innervating the GI tract to initiate appropriate functional responses. PURPOSE This review will highlight the role played by the EECs in the complex and integrated sensory information responses, and discuss the new findings regarding EECs in the brain-gut axis bidirectional communication.
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Affiliation(s)
- R Latorre
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - C Sternini
- CURE Digestive Diseases Research Center, Division of Digestive Diseases and Departments of Medicine and Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - R De Giorgio
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - B Greenwood-Van Meerveld
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Physiology, Veterans Affairs Medical Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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24
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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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25
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Abdulnour-Nakhoul S, Brown KL, Rabon EC, Al-Tawil Y, Islam MT, Schmieg JJ, Nakhoul NL. Cytoskeletal changes induced by allosteric modulators of calcium-sensing receptor in esophageal epithelial cells. Physiol Rep 2015; 3:3/11/e12616. [PMID: 26603452 PMCID: PMC4673644 DOI: 10.14814/phy2.12616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The calcium-sensing receptor (CaSR), a G-protein-coupled receptor, plays a role in glandular and fluid secretion in the gastrointestinal tract, and regulates differentiation and proliferation of epithelial cells. We examined the expression of CaSR in normal and pathological conditions of human esophagus and investigated the effect of a CaSR agonist, cinacalcet (CCT), and antagonist, calhex (CHX), on cell growth and cell-cell junctional proteins in primary cultures of porcine stratified squamous esophageal epithelium. We used immunohistochemistry and Western analysis to monitor expression of CaSR and cell-cell adhesion molecules, and MTT assay to monitor cell proliferation in cultured esophageal cells. CCT treatment significantly reduced proliferation, changed the cell shape from polygonal to spindle-like, and caused redistribution of E-cadherin and β-catenin from the cell membrane to the cytoplasm. Furthermore, it reduced expression of β-catenin by 35% (P < 0.02) and increased expression of a proteolysis cleavage fragment of E-cadherin, Ecad/CFT2, by 2.3 folds (P < 0.01). On the other hand, CHX treatment enhanced cell proliferation by 27% (P < 0.01), increased the expression of p120-catenin by 24% (P < 0.04), and of Rho, a GTPase involved in cytoskeleton remodeling, by 18% (P < 0.03). In conclusion, CaSR is expressed in normal esophagus as well as in Barrett's, esophageal adenocarcinoma, squamous cell carcinoma, and eosinophilic esophagitis. Long-term activation of CaSR with CCT disrupted the cadherin-catenin complex, induced cytoskeletal remodeling, actin fiber formation, and redistribution of CaSR to the nuclear area. These changes indicate a significant and complex role of CaSR in epithelial remodeling and barrier function of esophageal cells.
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Affiliation(s)
- Solange Abdulnour-Nakhoul
- Medicine/Gastroenterology, Tulane Medical School, New Orleans, Louisiana South Louisiana Veterans Health Care System (SLVHCS), New Orleans, Louisiana
| | - Karen L Brown
- South Louisiana Veterans Health Care System (SLVHCS), New Orleans, Louisiana Medicine/Nephrology, Tulane Medical School, New Orleans, Louisiana
| | - Edd C Rabon
- South Louisiana Veterans Health Care System (SLVHCS), New Orleans, Louisiana
| | - Youhanna Al-Tawil
- Pediatric Gastroenterology and Nutrition-GI for Kids, East Tennessee Children's Hospital, Knoxville, Tennessee
| | - Mohammed T Islam
- South Louisiana Veterans Health Care System (SLVHCS), New Orleans, Louisiana Medicine/Nephrology, Tulane Medical School, New Orleans, Louisiana
| | - John J Schmieg
- Pathology, Tulane Medical School, New Orleans, Louisiana
| | - Nazih L Nakhoul
- South Louisiana Veterans Health Care System (SLVHCS), New Orleans, Louisiana Medicine/Nephrology, Tulane Medical School, New Orleans, Louisiana
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Mine Y, Zhang H. Calcium-sensing receptor (CaSR)-mediated anti-inflammatory effects of L-amino acids in intestinal epithelial cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:9987-9995. [PMID: 26551350 DOI: 10.1021/acs.jafc.5b03749] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Calcium-sensing receptor (CaSR) plays an essential role in sensing nutrients and monitoring ion balance in the human gut. However, no discovery of CaSR-mediated anti-inflammatory effect of l-amino acids (l-AAs) on the gut system has been reported. The aim of this study is to screen and identify the anti-inflammatory activity of various l-AAs in intestinal epithelial cells (IECs) and stepwise illustrate a possible molecular mechanism for anti-inflammation. We used Caco-2 and HT-29 cell lines to evaluate the anti-inflammatory activity of l-AAs and revealed that l-tryptophan (l-Trp) and l-valine (l-Val) have strong anti-inflammatory activity consistent in both cell lines. l-Trp treatment (5 mM) reduced TNF-α-induced IL-8 secretion from HT-29 or Caco-2 cells to about 50 or 40%, respectively. l-Trp also significantly inhibited the expression of phosphorylation of JNK or IκBα to around 50% in HT-29 cells. However, the above inhibitory effects of l-Trp on inflammatory responses in TNF-α-induced HT-29 cells were abrogated by NPS-2143. The result of CaSR antagonist NPS-2143 pretreatment study suggests l-Trp exerts anti-inflammatory effects on IECs through CaSR activation. The involvement of β-arrestin2 was then found to block tumor necrosis factor (TNF)-α-induced signaling pathways after CaSR activated by l-Trp. These results validate a novel mechanism underlying CaSR agonistic l-AAs exerting anti-inflammatory effects on human intestinal epithelia.
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Affiliation(s)
- Yoshinori Mine
- Department of Food Science, University of Guelph , Guelph, Ontario N1G 2W1, Canada
| | - Hua Zhang
- Department of Food Science, University of Guelph , Guelph, Ontario N1G 2W1, Canada
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Massy ZA, Hénaut L, Larsson TE, Vervloet MG. Calcium-sensing receptor activation in chronic kidney disease: effects beyond parathyroid hormone control. Semin Nephrol 2015; 34:648-59. [PMID: 25498383 DOI: 10.1016/j.semnephrol.2014.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Secondary hyperparathyroidism (SHPT) is an important complication of advanced chronic kidney disease (CKD). Cinacalcet, an allosteric modulator of the calcium-sensing receptor (CaSR) expressed in parathyroid glands, is the only calcimimetic approved to treat SHPT in patients on dialysis. By enhancing CaSR sensitivity for plasma extracellular calcium (Ca(2+)0), cinacalcet reduces serum parathyroid hormone, Ca(2+)0, and serum inorganic phosphorous concentrations, allowing better control of SHPT and CKD-mineral and bone disorders. Of interest, the CaSR also is expressed in a variety of tissues where its activation regulates diverse cellular processes, including secretion, apoptosis, and proliferation. Thus, the existence of potential off-target effects of cinacalcet cannot be neglected. This review summarizes our current knowledge concerning the potential role(s) of the CaSR expressed in various tissues in CKD-related disorders, independently of parathyroid hormone control.
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Affiliation(s)
- Ziad A Massy
- Inserm U-1088, University of Picardie Jules Verne, Amiens, France; Division of Nephrology, Ambroise Paré Hospital, Paris-Ile-de-France-Ouest University (University of Versailles Saint-Quentin-En-Yvelines), Paris-Boulogne Billancourt, France.
| | - Lucie Hénaut
- Inserm U-1088, University of Picardie Jules Verne, Amiens, France
| | - Tobias E Larsson
- Department of Clinical Science, Intervention and Technology, Renal Unit, Karolinska Institutet, Stockholm, Sweden; Department of Nephrology, Karolinska University Hospital, Stockholm, Sweden
| | - Marc G Vervloet
- Department of Nephrology and Institute of Cardiovascular Research VU (Institute for Cardiovascular Research of the Vrije Universiteit of Amsterdam), VU University Medical Center, Amsterdam, The Netherlands
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Cook AE, Mistry SN, Gregory KJ, Furness SGB, Sexton PM, Scammells PJ, Conigrave AD, Christopoulos A, Leach K. Biased allosteric modulation at the CaS receptor engendered by structurally diverse calcimimetics. Br J Pharmacol 2015; 172:185-200. [PMID: 25220431 PMCID: PMC4280977 DOI: 10.1111/bph.12937] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 09/02/2014] [Accepted: 09/07/2014] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Clinical use of cinacalcet in hyperparathyroidism is complicated by its tendency to induce hypocalcaemia, arising partly from activation of calcium-sensing receptors (CaS receptors) in the thyroid and stimulation of calcitonin release. CaS receptor allosteric modulators that selectively bias signalling towards pathways that mediate desired effects [e.g. parathyroid hormone (PTH) suppression] rather than those mediating undesirable effects (e.g. elevated serum calcitonin), may offer better therapies. EXPERIMENTAL APPROACH We characterized the ligand-biased profile of novel calcimimetics in HEK293 cells stably expressing human CaS receptors, by monitoring intracellular calcium (Ca(2+) i ) mobilization, inositol phosphate (IP)1 accumulation, ERK1/2 phosphorylation (pERK1/2) and receptor expression. KEY RESULTS Phenylalkylamine calcimimetics were biased towards allosteric modulation of Ca(2+) i mobilization and IP1 accumulation. S,R-calcimimetic B was biased only towards IP1 accumulation. R,R-calcimimetic B and AC-265347 were biased towards IP1 accumulation and pERK1/2. Nor-calcimimetic B was unbiased. In contrast to phenylalkylamines and calcimimetic B analogues, AC-265347 did not promote trafficking of a loss-of-expression, naturally occurring, CaS receptor mutation (G(670) E). CONCLUSIONS AND IMPLICATIONS The ability of R,R-calcimimetic B and AC-265347 to bias signalling towards pERK1/2 and IP1 accumulation may explain their suppression of PTH levels in vivo at concentrations that have no effect on serum calcitonin levels. The demonstration that AC-265347 promotes CaS receptor receptor signalling, but not trafficking reveals a novel profile of ligand-biased modulation at CaS receptors The identification of allosteric modulators that bias CaS receptor signalling towards distinct intracellular pathways provides an opportunity to develop desirable biased signalling profiles in vivo for mediating selective physiological responses.
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Affiliation(s)
- A E Cook
- Drug Discovery Biology and Department of Pharmacology, Monash University, Parkville, Vic., Australia
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Letz S, Haag C, Schulze E, Frank-Raue K, Raue F, Hofner B, Mayr B, Schöfl C. Amino alcohol- (NPS-2143) and quinazolinone-derived calcilytics (ATF936 and AXT914) differentially mitigate excessive signalling of calcium-sensing receptor mutants causing Bartter syndrome Type 5 and autosomal dominant hypocalcemia. PLoS One 2014; 9:e115178. [PMID: 25506941 PMCID: PMC4266668 DOI: 10.1371/journal.pone.0115178] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 11/19/2014] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION Activating calcium sensing receptor (CaSR) mutations cause autosomal dominant hypocalcemia (ADH) characterized by low serum calcium, inappropriately low PTH and relative hypercalciuria. Four activating CaSR mutations cause additional renal wasting of sodium, chloride and other salts, a condition called Bartter syndrome (BS) type 5. Until today there is no specific medical treatment for BS type 5 and ADH. We investigated the effects of different allosteric CaSR antagonists (calcilytics) on activating CaSR mutants. METHODS All 4 known mutations causing BS type 5 and five ADH mutations were expressed in HEK 293T cells and receptor signalling was studied by measurement of intracellular free calcium in response to extracellular calcium ([Ca2+]o). To investigate the effect of calcilytics, cells were stimulated with 3 mM [Ca2+]o in the presence or absence of NPS-2143, ATF936 or AXT914. RESULTS All BS type 5 and ADH mutants showed enhanced signalling activity to [Ca2+]o with left shifted dose response curves. In contrast to the amino alcohol NPS-2143, which was only partially effective, the quinazolinone calcilytics ATF936 and AXT914 significantly mitigated excessive cytosolic calcium signalling of all BS type 5 and ADH mutants studied. When these mutants were co-expressed with wild-type CaSR to approximate heterozygosity in patients, ATF936 and AXT914 were also effective on all mutants. CONCLUSION The calcilytics ATF936 and AXT914 are capable of attenuating enhanced cytosolic calcium signalling activity of CaSR mutations causing BS type 5 and ADH. Quinazolinone calcilytics might therefore offer a novel treatment option for patients with activating CaSR mutations.
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Affiliation(s)
- Saskia Letz
- Division of Endocrinology and Diabetes, Department of Medicine I, Universitätsklinikum Erlangen, Erlangen, Germany
| | | | | | | | | | - Benjamin Hofner
- Department of Medical Informatics, Biometry and Epidemiology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Bernhard Mayr
- Division of Endocrinology and Diabetes, Department of Medicine I, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Christof Schöfl
- Division of Endocrinology and Diabetes, Department of Medicine I, Universitätsklinikum Erlangen, Erlangen, Germany
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Goolam MA, Ward JH, Avlani VA, Leach K, Christopoulos A, Conigrave AD. Roles of intraloops-2 and -3 and the proximal C-terminus in signalling pathway selection from the human calcium-sensing receptor. FEBS Lett 2014; 588:3340-6. [PMID: 25080008 DOI: 10.1016/j.febslet.2014.07.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 07/03/2014] [Accepted: 07/16/2014] [Indexed: 12/24/2022]
Abstract
The calcium-sensing receptor (CaSR) couples to signalling pathways via intracellular loops 2 and 3, and the C-terminus. However, the requirements for signalling are largely undefined. We investigated the impacts of selected point mutations in iL-2 (F706A) and iL-3 (L797A and E803A), and a truncation of the C-terminus (R866X) on extracellular Ca(2+) (Ca(2+)o)-stimulated phosphatidylinositol-specific phospholipase-C (PI-PLC) and various other signalling responses. CaSR-mediated activation of PI-PLC was markedly attenuated in all four mutants and similar suppressions were observed for Ca(2+)o-stimulated ERK1/2 phosphorylation. Ca(2+)o-stimulated intracellular Ca(2+) (Ca(2+)i) mobilization, however, was relatively preserved for the iL-2 and iL-3 mutants and suppression of adenylyl cyclase was unaffected by either E803A or R866X. The CaSR selects for specific signalling pathways via the proximal C-terminus and key residues in iL-2, iL-3.
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Affiliation(s)
- Mahvash A Goolam
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - James H Ward
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Vimesh A Avlani
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Katie Leach
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur D Conigrave
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
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