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Modvig IM, Smits MM, Galsgaard KD, Hjørne AP, Drzazga AK, Rosenkilde MM, Holst JJ. L-valine is a powerful stimulator of GLP-1 secretion in rodents and stimulates secretion through ATP-sensitive potassium channels and voltage-gated calcium channels. Nutr Diabetes 2024; 14:43. [PMID: 38862477 PMCID: PMC11166632 DOI: 10.1038/s41387-024-00303-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 05/30/2024] [Accepted: 06/04/2024] [Indexed: 06/13/2024] Open
Abstract
BACKGROUND We previously reported that, among all the naturally occurring amino acids, L-valine is the most powerful luminal stimulator of glucagon-like peptide 1 (GLP-1) release from the upper part of the rat small intestine. This makes L-valine an interesting target for nutritional-based modulation of GLP-1 secretion. However, the molecular mechanism of L-valine-induced secretion remains unknown. METHODS We aimed to investigate the effect of orally given L-valine in mice and to identify the molecular details of L-valine stimulated GLP-1 release using the isolated perfused rat small intestine and GLUTag cells. In addition, the effect of L-valine on hormone secretion from the distal intestine was investigated using a perfused rat colon. RESULTS Orally given L-valine (1 g/kg) increased plasma levels of active GLP-1 comparably to orally given glucose (2 g/kg) in male mice, supporting that L-valine is a powerful stimulator of GLP-1 release in vivo (P > 0.05). Luminal L-valine (50 mM) strongly stimulated GLP-1 release from the perfused rat small intestine (P < 0.0001), and inhibition of voltage-gated Ca2+-channels with nifedipine (10 μM) inhibited the GLP-1 response (P < 0.01). Depletion of luminal Na+ did not affect L-valine-induced GLP-1 secretion (P > 0.05), suggesting that co-transport of L-valine and Na+ is not important for the depolarization necessary to activate the voltage-gated Ca2+-channels. Administration of the KATP-channel opener diazoxide (250 μM) completely blocked the L-valine induced GLP-1 response (P < 0.05), suggesting that L-valine induced depolarization arises from metabolism and opening of KATP-channels. Similar to the perfused rat small intestine, L-valine tended to stimulate peptide tyrosine-tyrosine (PYY) and GLP-1 release from the perfused rat colon. CONCLUSIONS L-valine is a powerful stimulator of GLP-1 release in rodents. We propose that intracellular metabolism of L-valine leading to closure of KATP-channels and opening of voltage-gated Ca2+-channels are involved in L-valine induced GLP-1 secretion.
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Affiliation(s)
- Ida Marie Modvig
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mark M Smits
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Katrine Douglas Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anna Pii Hjørne
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anna Katarzyna Drzazga
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Łódź, Poland
| | - Mette Marie Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.
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2
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Barton JR, Londregan AK, Alexander TD, Entezari AA, Covarrubias M, Waldman SA. Enteroendocrine cell regulation of the gut-brain axis. Front Neurosci 2023; 17:1272955. [PMID: 38027512 PMCID: PMC10662325 DOI: 10.3389/fnins.2023.1272955] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Enteroendocrine cells (EECs) are an essential interface between the gut and brain that communicate signals about nutrients, pain, and even information from our microbiome. EECs are hormone-producing cells expressed throughout the gastrointestinal epithelium and have been leveraged by pharmaceuticals like semaglutide (Ozempic, Wegovy), terzepatide (Mounjaro), and retatrutide (Phase 2) for diabetes and weight control, and linaclotide (Linzess) to treat irritable bowel syndrome (IBS) and visceral pain. This review focuses on role of intestinal EECs to communicate signals from the gut lumen to the brain. Canonically, EECs communicate information about the intestinal environment through a variety of hormones, dividing EECs into separate classes based on the hormone each cell type secretes. Recent studies have revealed more diverse hormone profiles and communication modalities for EECs including direct synaptic communication with peripheral neurons. EECs known as neuropod cells rapidly relay signals from gut to brain via a direct communication with vagal and primary sensory neurons. Further, this review discusses the complex information processing machinery within EECs, including receptors that transduce intraluminal signals and the ion channel complement that govern initiation and propagation of these signals. Deeper understanding of EEC physiology is necessary to safely treat devastating and pervasive conditions like irritable bowel syndrome and obesity.
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Affiliation(s)
- Joshua R. Barton
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Annie K. Londregan
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Tyler D. Alexander
- Department of Neurosciences, Thomas Jefferson University, Philadelphia, PA, United States
| | - Ariana A. Entezari
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Manuel Covarrubias
- Department of Neurosciences, Thomas Jefferson University, Philadelphia, PA, United States
| | - Scott A. Waldman
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States
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3
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Zhang M, Zhu L, Wu G, Zhang H, Wang X, Qi X. The impacts and mechanisms of dietary proteins on glucose homeostasis and food intake: a pivotal role of gut hormones. Crit Rev Food Sci Nutr 2023:1-15. [PMID: 37800337 DOI: 10.1080/10408398.2023.2256400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Glucose and energy metabolism disorders are the main reasons induced type 2 diabetes (T2D) and obesity. Besides providing energy, dietary nutrients could regulate glucose homeostasis and food intake via intestinal nutrient sensing induced gut hormone secretion. However, reviews regarding intestinal protein sensing are very limited, and no accurate information is available on their underlying mechanisms. Through intestinal protein sensing, dietary proteins regulate glucose homeostasis and food intake by secreting gut hormones, such as glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY) and glucose-dependent insulinotropic polypeptide (GIP). After activating the sensory receptors, such as calcium-sensing receptor (CaSR), peptide transporter-1 (PepT1), and taste 1 receptors (T1Rs), protein digests induced Ca2+ influx and thus triggered gut hormone release. Additionally, research models used to study intestinal protein sensing have been emphasized, especially several innovative models with excellent physiological relevance, such as co-culture cell models, intestinal organoids, and gut-on-a-chips. Lastly, protein-based dietary strategies that stimulate gut hormone secretion and inhibit gut hormone degradation are proposed for regulating glucose homeostasis and food intake.
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Affiliation(s)
- Mingkai Zhang
- National Engineering Research Center for Functional Food, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Ling Zhu
- National Engineering Research Center for Functional Food, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Gangcheng Wu
- National Engineering Research Center for Functional Food, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Hui Zhang
- National Engineering Research Center for Functional Food, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Xingguo Wang
- National Engineering Research Center for Functional Food, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Xiguang Qi
- National Engineering Research Center for Functional Food, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, School of Food Science and Technology, Jiangnan University, Wuxi, China
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4
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Yanagisawa Y. How dietary amino acids and high protein diets influence insulin secretion. Physiol Rep 2023; 11:e15577. [PMID: 36695783 PMCID: PMC9875820 DOI: 10.14814/phy2.15577] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/26/2022] [Accepted: 12/31/2022] [Indexed: 01/26/2023] Open
Abstract
Glucose homeostasis is the maintenance and regulation of blood glucose concentration within a tight physiological range, essential for the functioning of most tissues and organs. This is primarily achieved by pancreatic secretion of insulin and glucagon. Deficient pancreatic endocrine function, coupled with or without peripheral insulin resistance leads to prolonged hyperglycemia with chronic impairment of glucose homeostasis, most commonly seen in diabetes mellitus. High protein diets (HPDs) are thought to modulate glucose homeostasis through various metabolic pathways. Insulin secretion can be directly modulated by the amino acid products of protein digestion, which activate nutrient receptors and nutrient transporters expressed by the endocrine pancreas. Insulin secretion can also be modulated indirectly, through incretin release from enteroendocrine cells, and via vagal neuronal pathways. Additionally, glucose homeostasis can be promoted by the satiating effects of anorectic hormones released following HPD consumption. This review summarizes the insulinotropic mechanisms by which amino acids and HPDs may influence glucose homeostasis, with a particular focus on their applicability in the management of Type 2 diabetes mellitus.
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Affiliation(s)
- Yuuki Yanagisawa
- Department of Metabolism, Digestion and ReproductionImperial College LondonLondonUK
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5
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Development of a red fluorescent protein-based cGMP indicator applicable for live-cell imaging. Commun Biol 2022; 5:833. [PMID: 36064581 PMCID: PMC9445041 DOI: 10.1038/s42003-022-03790-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 08/02/2022] [Indexed: 11/08/2022] Open
Abstract
Cyclic guanosine 3', 5'-monophosphate (cGMP) is a second messenger that regulates a variety of physiological processes. Here, we develop a red fluorescent protein-based cGMP indicator, "Red cGull". The fluorescence intensity of Red cGull increase more than sixfold in response to cGMP. The features of this indicator include an EC50 of 0.33 μM for cGMP, an excitation and emission peak at 567 nm and 591 nm, respectively. Live-cell imaging analysis reveal the utility of Red cGull for dual-colour imaging and its ability to be used in conjunction with optogenetics tools. Using enteroendocrine cell lines, Red cGull detects an increase in cGMP following the application of L-arginine. An increase in intracellular cGMP is found to be inhibited by Ca2+, and L-arginine-mediated hormone secretion is not potentiated. We propose that Red cGull will facilitate future research in cell signalling in relation to cGMP and its interplay with other signalling molecules.
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6
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GPRC6A Mediates Glucose and Amino Acid Homeostasis in Mice. Metabolites 2022; 12:metabo12080740. [PMID: 36005612 PMCID: PMC9415337 DOI: 10.3390/metabo12080740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/03/2022] [Accepted: 08/08/2022] [Indexed: 11/29/2022] Open
Abstract
GPRC6A, an important member of the G-protein-coupled receptor superfamily, has been widely studied in body health maintenance and related diseases. However, it is still controversial whether GPRC6A plays a vital role in glucose homeostasis, and the role of GPRC6A on amino acid homeostasis has not been reported. In this study, GPRC6A was knocked out in C57BL6 mice, and we found that GPRC6A plays an important role in the glucose metabolism, mainly affecting the glucose clearance capacity and gluconeogenesis in mice. GPRC6A plays an important role in maintaining amino acid homeostasis under dietary restrictions, and this may be realized by participating in the regulation of autophagy. Since a large amount of amino acid is lost from urine in aged GPRC6A−/− mice, it is possible that GPRC6A regulates amino acid homeostasis by affecting the integrity of tissue structure. GPRC6A is involved in the regulation of mTORC1 activation but is not necessary for mTORC1 activation under sufficient nutritional supply. In the absence of exogenous amino acids, the loss of GPRC6A induces the GCN2 pathway activation and excessive autophagy of cells, leading to the overactivation of mTORC1, which may be detrimental to body health and cell survival. In summary, this study provides a theoretical and experimental basis for the metabolic process of GPRC6A in body growth and health.
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7
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Taniguchi E, Hattori A, Kurogi K, Hishida Y, Watanabe F, Furuse M, Yasuo S. Temporal patterns of increased growth hormone secretion in mice after oral administration of L-ornithine: possible involvement of ghrelin receptors. J Vet Med Sci 2022; 84:1283-1287. [PMID: 35896372 PMCID: PMC9523286 DOI: 10.1292/jvms.22-0125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
l-Ornithine is known to stimulate growth hormone (GH) release in mammals. Here, we demonstrated that increases in plasma GH levels after oral administration of l-ornithine
were first observed 150 min after administration, and the elevated levels were sustained for more than 90 min in mice. The increase was significantly delayed compared with the reported
timing of plasma and tissue levels of l-ornithine after administration. The l-ornithine-induced increase in GH release was completely blocked by [D-Lys3]-GHRP-6,
a ghrelin receptor antagonist, but not by cyclosomatostatin or JV-1-38, antagonists of somatostatin and GH-releasing hormone, respectively. These results suggest the involvement of ghrelin
receptor-mediated pathways in l-ornithine-induced increases in GH release.
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Affiliation(s)
- Emi Taniguchi
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University
| | - Ayumi Hattori
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University
| | - Kaito Kurogi
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University
| | | | | | - Mitsuhiro Furuse
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University
| | - Shinobu Yasuo
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University
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8
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The Sensory Mechanisms of Nutrient-Induced GLP-1 Secretion. Metabolites 2022; 12:metabo12050420. [PMID: 35629924 PMCID: PMC9147592 DOI: 10.3390/metabo12050420] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/03/2022] [Accepted: 05/05/2022] [Indexed: 02/05/2023] Open
Abstract
The enteroendocrine system of the gut regulates energy homeostasis through the release of hormones. Of the gut-derived hormones, GLP-1 is particularly interesting, as analogs of the hormone have proven to be highly effective for the treatment of type 2 diabetes mellitus and obesity. Observations on increased levels of GLP-1 following gastric bypass surgery have enhanced the interest in endogenous hormone secretion and highlighted the potential of endogenous secretion in therapy. The macronutrients and their digestive products stimulate the secretion of GLP-1 through various mechanisms that we have only begun to understand. From findings obtained from different experimental models, we now have strong indications for a role for both Sodium-Glucose Transporter 1 (SGLT1) and the K+ATP channel in carbohydrate-induced GLP-1 secretion. For fat, the free fatty acid receptor FFA1 and the G-protein-coupled receptor GPR119 have been linked to GLP-1 secretion. For proteins, Peptide Transporter 1 (Pept1) and the Calcium-Sensing Receptor (CaSR) are thought to mediate the secretion. However, attempts at clinical application of these mechanisms have been unsuccessful, and more work is needed before we fully understand the mechanisms of nutrient-induced GLP-1 secretion.
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9
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Qin W, Ying W, Hamaker B, Zhang G. Slow digestion-oriented dietary strategy to sustain the secretion of GLP-1 for improved glucose homeostasis. Compr Rev Food Sci Food Saf 2021; 20:5173-5196. [PMID: 34350681 DOI: 10.1111/1541-4337.12808] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/08/2021] [Accepted: 06/24/2021] [Indexed: 12/18/2022]
Abstract
Dysregulated glucose metabolism is associated with many chronic diseases such as obesity and type 2 diabetes mellitus (T2DM), and strategies to restore and maintain glucose homeostasis are essential to health. The incretin hormone of glucagon-like peptide-1 (GLP-1) is known to play a critical role in regulating glucose homeostasis and dietary nutrients are the primary stimuli to the release of intestinal GLP-1. However, the GLP-1 producing enteroendocrine L-cells are mainly distributed in the distal region of the gastrointestinal tract where there are almost no nutrients to stimulate the secretion of GLP-1 under normal situations. Thus, a dietary strategy to sustain the release of GLP-1 was proposed, and the slow digestion property and dipeptidyl peptidase IV (DPP-IV) inhibitory activity of food components, approaches to reduce the rate of food digestion, and mechanisms to sustain the release of GLP-1 were reviewed. A slow digestion-oriented dietary approach through encapsulation of nutrients, incorporation of viscous dietary fibers, and enzyme inhibitors of phytochemicals in a designed whole food matrix will be implemented to efficiently reduce the digestion rate of food nutrients, potentiate their distal deposition and a sustained secretion of GLP-1, which will be beneficial to improved glucose homeostasis and health.
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Affiliation(s)
- Wangyan Qin
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Wang Ying
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Bruce Hamaker
- Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, Indiana, USA
| | - Genyi Zhang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China
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10
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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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11
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Hira T, Trakooncharoenvit A, Taguchi H, Hara H. Improvement of Glucose Tolerance by Food Factors Having Glucagon-Like Peptide-1 Releasing Activity. Int J Mol Sci 2021; 22:6623. [PMID: 34205659 PMCID: PMC8235588 DOI: 10.3390/ijms22126623] [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: 05/25/2021] [Revised: 06/17/2021] [Accepted: 06/17/2021] [Indexed: 12/14/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone released from enteroendocrine L cells in response to meal ingestion. GLP-1 receptor agonists and GLP-1 enhancers have been clinically employed to treat diabetes owing to their glucose-dependent insulin-releasing activity. The release of GLP-1 is primarily stimulated by macronutrients such as glucose and fatty acids, which are nutritionally indispensable; however, excessive intake of sugar and fat is responsible for the development of obesity and diabetes. Therefore, GLP-1 releasing food factors, such as dietary peptides and non-nutrients, are deemed desirable for improving glucose tolerance. Human and animal studies have revealed that dietary proteins/peptides have a potent effect on stimulating GLP-1 secretion. Studies in enteroendocrine cell models have shown that dietary peptides, amino acids, and phytochemicals, such as quercetin, can directly stimulate GLP-1 secretion. In our animal experiments, these food factors improved glucose metabolism and increased GLP-1 secretion. Furthermore, some dietary peptides not only stimulated GLP-1 secretion but also reduced plasma peptidase activity, which is responsible for GLP-1 inactivation. Herein, we review the relationship between GLP-1 and food factors, especially dietary peptides and flavonoids. Accordingly, utilization of food factors with GLP-1-releasing/enhancing activity is a promising strategy for preventing and treating obesity and diabetes.
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Affiliation(s)
- Tohru Hira
- Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
- Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan;
- School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan;
| | | | - Hayate Taguchi
- School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan;
| | - Hiroshi Hara
- Department of Food Science and Human Nutrition, Fuji Women’s University, Ishikari-shi 061-320, Japan;
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12
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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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Pi M, Nishimoto SK, Darryl Quarles L. Explaining Divergent Observations Regarding Osteocalcin/GPRC6A Endocrine Signaling. Endocrinology 2021; 162:6104945. [PMID: 33474566 PMCID: PMC7880225 DOI: 10.1210/endocr/bqab011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Indexed: 12/13/2022]
Abstract
A new schema proposes that the bone-derived osteocalcin (Ocn) peptide hormone activates the G-protein-coupled receptor GPRC6A to directly regulate glucose and fat metabolism in liver, muscle, and fat, and to stimulate the release of metabolism-regulating hormones, including insulin, fibroblast growth factor 21, glucagon-like peptide 1, testosterone, and interleukin 6. Ocn/GPRC6A activation has also been implicated in cancer progression. GPRC6A is activated by cations, amino acids, and testosterone. The multiligand specificity, the regulation of energy metabolism in diverse tissues, and the coordinated release of metabolically active hormones make the GPRC6A endocrine networks unique. Recently, the significance of Ocn/GPRCA has been questioned. There is a lack of metabolic abnormalities in newly created genetically engineered Ocn- and Gprc6a-deficient mouse models. There are also paradoxical observations that GPRC6A may function as a tumor suppressor. In addition, discordant published studies have cast doubt on the function of the most prevalent uniquely human GPRC6A-KGKY polymorphism. Explanations for these divergent findings are elusive. We provide evidence that the metabolic susceptibility of genetically engineered Ocn- and Gprc6a-deficient mice is influenced by environmental challenges and genetic differences in mouse strains. In addition, the GPRC6A-KGKY polymorphism appears to be a gain-of-function variant. Finally, alternatively spliced isoforms of GPRC6A may alter ligand specificity and signaling that modulate oncogenic effects. Thus, genetic, post-translational and environmental factors likely account for the variable results regarding the functions of GPRC6A in animal models. Pending additional information, GPRC6A should remain a potential therapeutic target for regulating energy and fat metabolism, hormone production, and cancer progression.
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Affiliation(s)
- Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Satoru Kenneth Nishimoto
- Department of Microbiology, Immunology & Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - L Darryl Quarles
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
- Correspondence: L. Darryl Quarles, MD, University of Tennessee Health Sciences Center, Memphis, TN, USA. . Current Affiliation: 965 Court Ave, Suite B226, Memphis, TN 38163, USA
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Kang C, Wang L, Feng J, Zhu W, Hang S. l-Glutamate stimulates cholecystokinin secretion via the T1R1/T1R3 mediated PLC/TRPM5 transduction pathway. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2020; 100:4818-4825. [PMID: 32478409 DOI: 10.1002/jsfa.10541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/17/2020] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND It is known that cholecystokinin (CCK) plays an essential role in reducing food intake and driving weight loss. Previous studies demonstrated that amino acids were capable of triggering CCK release through G protein-coupled receptors, but the sensing mechanism remains obscure, especially the intracellular signaling pathway. RESULTS l-Glu, rather than its d-isomer, robustly stimulated CCK secretion in a porcine duodenal model, and the secretory response was augmented by incubation with the allosteric ligand of T1R1, while T1R3 antagonist attenuated it. Upon inhibiting phospholipase C (PLC) or transient receptor potential M5 (TRPM5) activity, l-Glu failed to increase CCK release. Oral administration of monosodium glutamate in rats also suppressed food intake and increased plasma CCK levels, accompanied by elevated expression of T1R1, PLCβ2 and TRPM5 in the duodenum. CONCLUSION These data demonstrated that l-Glu stimulated CCK secretion through the activation of T1R1/T1R3 in a PLC/TRPM5-dependent manner. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Cuicui Kang
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Lvyang Wang
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Jiangyin Feng
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Weiyun Zhu
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Suqin Hang
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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15
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Enteroendocrine Hormone Secretion and Metabolic Control: Importance of the Region of the Gut Stimulation. Pharmaceutics 2020; 12:pharmaceutics12090790. [PMID: 32825608 PMCID: PMC7559385 DOI: 10.3390/pharmaceutics12090790] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/19/2020] [Accepted: 08/19/2020] [Indexed: 12/11/2022] Open
Abstract
It is now widely appreciated that gastrointestinal function is central to the regulation of metabolic homeostasis. Following meal ingestion, the delivery of nutrients from the stomach into the small intestine (i.e., gastric emptying) is tightly controlled to optimise their subsequent digestion and absorption. The complex interaction of intraluminal nutrients (and other bioactive compounds, such as bile acids) with the small and large intestine induces the release of an array of gastrointestinal hormones from specialised enteroendocrine cells (EECs) distributed in various regions of the gut, which in turn to regulate gastric emptying, appetite and postprandial glucose metabolism. Stimulation of gastrointestinal hormone secretion, therefore, represents a promising strategy for the management of metabolic disorders, particularly obesity and type 2 diabetes mellitus (T2DM). That EECs are distributed distinctively between the proximal and distal gut suggests that the region of the gut exposed to intraluminal stimuli is of major relevance to the secretion profile of gastrointestinal hormones and associated metabolic responses. This review discusses the process of intestinal digestion and absorption and their impacts on the release of gastrointestinal hormones and the regulation of postprandial metabolism, with an emphasis on the differences between the proximal and distal gut, and implications for the management of obesity and T2DM.
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16
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Fowlkes JL, Clay Bunn R, Kalaitzoglou E, Ray P, Popescu I, Thrailkill KM. Postnatal loss of the insulin receptor in osteoprogenitor cells does not impart a metabolic phenotype. Sci Rep 2020; 10:8842. [PMID: 32483283 PMCID: PMC7264347 DOI: 10.1038/s41598-020-65717-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/07/2020] [Indexed: 11/09/2022] Open
Abstract
The relationship between osteoblast-specific insulin signaling, osteocalcin activation and gluco-metabolic homeostasis has proven to be complex and potentially inconsistent across animal-model systems and in humans. Moreover, the impact of postnatally acquired, osteoblast-specific insulin deficiency on the pancreas-to-skeleton-to-pancreas circuit has not been studied. To explore this relationship, we created a model of postnatal elimination of insulin signaling in osteoprogenitors. Osteoprogenitor-selective ablation of the insulin receptor was induced after ~10 weeks of age in IRl°x/lox/Osx-Cre+/- genotypic male and female mice (designated postnatal-OIRKO). At ~21 weeks of age, mice were then phenotypically and metabolically characterized. Postnatal-OIRKO mice demonstrated a significant reduction in circulating concentrations of undercarboxylated osteocalcin (ucOC), in both males and females compared with control littermates. However, no differences were observed between postnatal-OIRKO and control mice in: body composition (lean or fat mass); fasting serum insulin; HbA1c; glucose dynamics during glucose tolerance testing; or in pancreatic islet area or islet morphology, demonstrating that while ucOC is impacted by insulin signaling in osteoprogenitors, there appears to be little to no relationship between osteocalcin, or its derivative (ucOC), and glucose homeostasis in this model.
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Affiliation(s)
- John L Fowlkes
- University of Kentucky, Barnstable Brown Diabetes Center, Lexington, KY, USA. .,Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
| | - R Clay Bunn
- University of Kentucky, Barnstable Brown Diabetes Center, Lexington, KY, USA.,Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Evangelia Kalaitzoglou
- University of Kentucky, Barnstable Brown Diabetes Center, Lexington, KY, USA.,Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Phil Ray
- University of Kentucky, Barnstable Brown Diabetes Center, Lexington, KY, USA
| | - Iuliana Popescu
- University of Kentucky, Barnstable Brown Diabetes Center, Lexington, KY, USA
| | - Kathryn M Thrailkill
- University of Kentucky, Barnstable Brown Diabetes Center, Lexington, KY, USA.,Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
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17
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Jørgensen CV, Bräuner‐Osborne H. Pharmacology and physiological function of the orphan GPRC6A receptor. Basic Clin Pharmacol Toxicol 2020; 126 Suppl 6:77-87. [DOI: 10.1111/bcpt.13397] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Christinna V. Jørgensen
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Hans Bräuner‐Osborne
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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18
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Tian M, Heng J, Song H, Zhang Y, Chen F, Guan W, Zhang S. Branched chain amino acids stimulate gut satiety hormone cholecystokinin secretion through activation of the umami taste receptor T1R1/T1R3 using an in vitro porcine jejunum model. Food Funct 2019; 10:3356-3367. [PMID: 31098606 DOI: 10.1039/c9fo00228f] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Branched chain amino acids (BCAAs) are essential amino acids involved in regulation of feed intake. The function of BCAAs on the central nervous system has been extensively studied, but effects of BCAAs on secretion of gut satiety hormones and their underlying mechanisms are largely unknown. In this study, we evaluated the distribution of gut hormones and amino acid receptors in the porcine GI tract and found cholecystokinin (CCK) and taste dimeric receptor type 1 member 1/3 (T1R1/T1R3) were predominantly expressed in the jejunum and functionally interrelated. We further evaluated the effects of l-leucine, l-isoleucine, l-valine, and BCAAs on CCK and T1R1/T1R3 expression in porcine jejunum tissue. Our data demonstrated that stimulation of porcine jejunum tissue with 10 mM l-leucine, l-isoleucine or BCAAs mix (l-leucine : l-isoleucine : l-valine = 1 : 0.51 : 0.63) for 2 hours significantly increased mRNA expression and protein abundance of T1R1/T1R3 and secretion of CCK (P < 0.05). However, the l-valine treatment only increased the mRNA and protein abundance of T1R1 and T1R3 (P < 0.05), but not CCK secretion (P > 0.10). l-Leucine-, l-isoleucine- or BCAAs mix-induced CCK secretion was significantly decreased after tissues were pretreated with lactisole, a T1R1/T1R3 inhibitor (P < 0.05). Furthermore, the increased mRNA and protein abundance of T1R1/T1R3 were also largely attenuated by blocking T1R1/T1R3 with lactisole (P < 0.05). l-Leucine, l-isoleucine and BCAAs mix appeared to induce the gut satiety hormone CCK secretion through jejunal T1R1/T1R3. These results indicate over-supplementation with BCAAs in the diet might decrease food intake in swine and humans through gastrointestinal feedback.
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Affiliation(s)
- Min Tian
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou 510642, People's Republic of China.
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Metabolic and skeletal homeostasis are maintained in full locus GPRC6A knockout mice. Sci Rep 2019; 9:5995. [PMID: 30979912 PMCID: PMC6461682 DOI: 10.1038/s41598-019-41921-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 03/20/2019] [Indexed: 11/08/2022] Open
Abstract
The G protein-coupled receptor class C, group 6, subtype A (GPRC6A) is suggested to have a physiological function in glucose and bone metabolism, although the precise role lacks consensus due to varying findings in different knockout (KO) mouse models and inconsistent findings on the role of osteocalcin, a proposed GPRC6A agonist. We have further characterized a full locus GPRC6A KO model with respect to energy metabolism, including a long-term high-dose glucocorticoid metabolic challenge. Additionally, we analyzed the microarchitecture of tibiae from young, middle-aged and aged GPRC6A KO mice and wildtype (WT) littermates. Compared to WT, vehicle-treated KO mice presented with normal body composition, unaltered insulin sensitivity and basal serum insulin and glucose levels. Corticosterone (CS) treatment resulted in insulin resistance, abnormal fat accrual, loss of lean mass and suppression of serum osteocalcin levels in both genotypes. Interestingly, serum osteocalcin and skeletal osteocalcin mRNA levels were significantly lower in vehicle-treated GPRC6A KO mice compared to WT animals. However, WT and KO age groups did not differ in long bone mass and structure assessed by micro-computed tomography. We conclude that GPRC6A is not involved in glucose metabolism under normal physiological conditions, nor does it mediate glucocorticoid-induced dysmetabolism in mice. Moreover, GPRC6A does not appear to possess a direct, non-compensable role in long bone microarchitecture under standard conditions.
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20
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Modvig IM, Kuhre RE, Holst JJ. Peptone-mediated glucagon-like peptide-1 secretion depends on intestinal absorption and activation of basolaterally located Calcium-Sensing Receptors. Physiol Rep 2019; 7:e14056. [PMID: 31020803 PMCID: PMC6482282 DOI: 10.14814/phy2.14056] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/15/2019] [Accepted: 03/16/2019] [Indexed: 01/13/2023] Open
Abstract
Protein intake robustly stimulates the secretion of the incretin hormone, glucagon-like peptide-1 (GLP-1) but the molecular mechanisms involved are not well understood. In particular, it is unknown whether proteins stimulate secretion by activation of luminal or basolateral sensors. We characterized the mechanisms using a physiologically relevant model - the isolated perfused proximal rat small intestine. Intraluminal protein hydrolysates derived from meat (peptone; 50 mg/mL) increased GLP-1 secretion 2.3-fold (from a basal secretion of 110 ± 28 fmol/min). The sensory mechanisms underlying the response depended on di/tripeptide uptake through Peptide Transporter 1 (PepT1) and subsequent basolateral activation of the amino acid sensing receptor, Calcium-Sensing Receptor (CaSR), since inhibition of PepT1 as well as CaSR both attenuated the peptone-induced GLP-1 response. Supporting this, intraluminal peptones were absorbed efficiently by the perfused intestine (resulting in increased amino acid concentrations in the venous effluent) and infusion of amino acids robustly stimulated GLP-1 secretion. Inhibitors of voltage-gated L-type Ca2+ channels had no effect on secretion suggesting that peptone-mediated GLP-1 secretion is not mediated by L-cell depolarization with subsequent opening of these channels. Specific targeting of CaSR could serve as a target to stimulate the endogenous secretion of GLP-1.
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Affiliation(s)
- Ida M. Modvig
- Department of Biomedical SciencesNNF Center for Basic Metabolic ResearchFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Rune E. Kuhre
- Department of Biomedical SciencesNNF Center for Basic Metabolic ResearchFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Jens Juul Holst
- Department of Biomedical SciencesNNF Center for Basic Metabolic ResearchFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
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21
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Santos-Hernández M, Miralles B, Amigo L, Recio I. Intestinal Signaling of Proteins and Digestion-Derived Products Relevant to Satiety. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:10123-10131. [PMID: 30056702 DOI: 10.1021/acs.jafc.8b02355] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Luminal nutrients stimulate enteroendocrine cells through the activation of specific receptors to release hormones that inhibit appetite and promote glucose homeostasis. While food protein is the macronutrient with the highest effect on satiety, the signaling on the protein digestion products at the gut is poorly understood. This perspective aims to highlight the existing gaps in the study of protein digestion products as signaling molecules in gastrointestinal enteroendocrine cells. Because dietary protein digestion can be modulated by the technological processes applied to food, it is possible to target gut receptors to control food intake by formulating specific food ingredients or protein preloads.
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Affiliation(s)
- Marta Santos-Hernández
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) , Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM) , Campus de Excelencia Internacional (CEI) UAM + CSIC, Nicolás Cabrera, 9 , 28049 Madrid , Spain
| | - Beatriz Miralles
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) , Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM) , Campus de Excelencia Internacional (CEI) UAM + CSIC, Nicolás Cabrera, 9 , 28049 Madrid , Spain
| | - Lourdes Amigo
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) , Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM) , Campus de Excelencia Internacional (CEI) UAM + CSIC, Nicolás Cabrera, 9 , 28049 Madrid , Spain
| | - Isidra Recio
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) , Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM) , Campus de Excelencia Internacional (CEI) UAM + CSIC, Nicolás Cabrera, 9 , 28049 Madrid , Spain
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22
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Brubaker PL. Glucagon‐like Peptide‐2 and the Regulation of Intestinal Growth and Function. Compr Physiol 2018; 8:1185-1210. [DOI: 10.1002/cphy.c170055] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
The gastrointestinal tract represents the largest interface between the human body and the external environment. It must continuously monitor and discriminate between nutrients that need to be assimilated and harmful substances that need to be expelled. The different cells of the gut epithelium are therefore equipped with a subtle chemosensory system that communicates the sensory information to several effector systems involved in the regulation of appetite, immune responses, and gastrointestinal motility. Disturbances or adaptations in the communication of this sensory information may contribute to the development or maintenance of disease. This is a new emerging research field in which perception of taste can be considered as a novel key player participating in the regulation of gut function. Specific diets or agonists that target these chemosensory signaling pathways may be considered as new therapeutic targets to tune adequate physiological processes in the gut in health and disease.
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Affiliation(s)
- S Steensels
- Translational Research Center for Gastrointestinal Disorders, KU Leuven, 3000 Leuven, Belgium;
| | - I Depoortere
- Translational Research Center for Gastrointestinal Disorders, KU Leuven, 3000 Leuven, Belgium;
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Paternoster S, Falasca M. Dissecting the Physiology and Pathophysiology of Glucagon-Like Peptide-1. Front Endocrinol (Lausanne) 2018; 9:584. [PMID: 30364192 PMCID: PMC6193070 DOI: 10.3389/fendo.2018.00584] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/14/2018] [Indexed: 12/11/2022] Open
Abstract
An aging world population exposed to a sedentary life style is currently plagued by chronic metabolic diseases, such as type-2 diabetes, that are spreading worldwide at an unprecedented rate. One of the most promising pharmacological approaches for the management of type 2 diabetes takes advantage of the peptide hormone glucagon-like peptide-1 (GLP-1) under the form of protease resistant mimetics, and DPP-IV inhibitors. Despite the improved quality of life, long-term treatments with these new classes of drugs are riddled with serious and life-threatening side-effects, with no overall cure of the disease. New evidence is shedding more light over the complex physiology of GLP-1 in health and metabolic diseases. Herein, we discuss the most recent advancements in the biology of gut receptors known to induce the secretion of GLP-1, to bridge the multiple gaps into our understanding of its physiology and pathology.
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25
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Targeting gastrointestinal nutrient sensing mechanisms to treat obesity. Curr Opin Pharmacol 2017; 37:16-23. [DOI: 10.1016/j.coph.2017.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 07/20/2017] [Indexed: 12/15/2022]
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26
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Lee J, Koehler J, Yusta B, Bahrami J, Matthews D, Rafii M, Pencharz PB, Drucker DJ. Enteroendocrine-derived glucagon-like peptide-2 controls intestinal amino acid transport. Mol Metab 2017; 6:245-255. [PMID: 28271031 PMCID: PMC5324020 DOI: 10.1016/j.molmet.2017.01.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 01/11/2017] [Indexed: 12/28/2022] Open
Abstract
Objective Glucagon-like peptide-2 (GLP-2) is co-secreted with GLP-1 from gut endocrine cells, and both peptides act as growth factors to expand the surface area of the mucosal epithelium. Notably, GLP-2 also enhances glucose and lipid transport in enterocytes; however, its actions on control of amino acid (AA) transport remain unclear. Here we examined the mechanisms linking gain and loss of GLP-2 receptor (GLP-2R) signaling to control of intestinal amino acid absorption in mice. Methods Absorption, transport, and clearance of essential AAs, specifically lysine, were measured in vivo by Liquid Chromatography triple quadrupole Mass Spectrometry (LC-MS/MS) and ex vivo with Ussing chambers using intestinal preparations from Glp2r+/+ and Glp2r−/− mice. Immunoblotting determined jejunal levels of protein components of signaling pathways (PI3K-AKT, and mTORC1-pS6-p4E-BP1) following administration of GLP-2, protein gavage, and rapamycin to fasted Glp2r+/+ and Glp2r−/− mice. Expression of AA transporters from full thickness jejunum and 4F2hc from brush border membrane vesicles (BBMVs) was measured by real-time PCR and immunoblotting, respectively. Results Acute administration of GLP-2 increased basal AA absorption in vivo and augmented basal lysine transport ex vivo. GLP-2-stimulated lysine transport was attenuated by co-incubation with wortmannin, rapamycin, or tetrodotoxin ex vivo. Phosphorylation of mTORC1 effector proteins S6 and 4E-BP1 was significantly increased in wild-type mice in response to GLP-2 alone, or when co-administered with protein gavage, and abolished following oral gavage of rapamycin. In contrast, activation of GLP-1R signaling did not enhance S6 phosphorylation. Disruption of GLP-2 action in Glp2r−/− mice reduced lysine transport ex vivo and attenuated the phosphorylation of S6 and 4E-BP1 in response to oral protein. Moreover, the expression of cationic AA transporter slc7a9 in response to refeeding, and the abundance of 4F2hc in BBMVs following protein gavage, was significantly attenuated in Glp2r−/− mice. Conclusions These findings reveal an important role for GLP-2R signaling in the physiological and pharmacological control of enteral amino acid sensing and assimilation, defining an enteroendocrine cell-enterocyte axis for optimal energy absorption. GLP-2 promotes intestinal amino acid absorption in vivo. Intestinal amino acid absorption is reduced in Glp2r−/− mice. GLP-2 stimulates amino acid transport independently of blood flow. GLP-2, but not GLP-1, activates the mTORC1 signaling pathway. Amino acid transport by GLP-2 requires the enteric nervous system and mTORC1.
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Key Words
- 4E-BP1, eukaryotic translation initiation factor 4E (eIF4e)-binding protein 1
- AA, amino acid
- Amino acid absorption
- BBMV, brush border membrane vesicles
- EAA, essential amino acid
- EECs, enteroendocrine cells
- ENS, enteric nervous system
- GLP-1
- GLP-1, Glucagon-like peptide-1
- GLP-2
- GLP-2, glucagon-like peptide-2
- GLP-2R, GLP-2 receptor
- Gut peptides
- LC-MS/MS, liquid chromatography triple quadrupole mass spectrometry
- PGDP, proglucagon-derived peptides
- Rapamycin
- S6K1, 70 kDa ribosomal protein S6 kinase 1
- mTORC1, mechanistic target of rapamycin complex 1
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Affiliation(s)
- Jennifer Lee
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Jacqueline Koehler
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Bernardo Yusta
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Jasmine Bahrami
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Dianne Matthews
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Mahroukh Rafii
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Paul B Pencharz
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Daniel J Drucker
- Department of Medicine, University of Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, ON M5G 1X5, Canada.
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Jørgensen S, Have CT, Underwood CR, Johansen LD, Wellendorph P, Gjesing AP, Jørgensen CV, Quan S, Rui G, Inoue A, Linneberg A, Grarup N, Jun W, Pedersen O, Hansen T, Bräuner-Osborne H. Genetic Variations in the Human G Protein-coupled Receptor Class C, Group 6, Member A (GPRC6A) Control Cell Surface Expression and Function. J Biol Chem 2016; 292:1524-1534. [PMID: 27986810 DOI: 10.1074/jbc.m116.756577] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/14/2016] [Indexed: 12/30/2022] Open
Abstract
GPRC6A is a G protein-coupled receptor activated by l-amino acids, which, based on analyses of knock-out mice, has been suggested to have physiological functions in metabolism and testicular function. The human ortholog is, however, mostly retained intracellularly in contrast to the cell surface-expressed murine and goldfish orthologs. The latter orthologs are Gq-coupled and lead to intracellular accumulation of inositol phosphates and calcium release. In the present study we cloned the bonobo chimpanzee GPRC6A receptor, which is 99% identical to the human receptor, and show that it is cell surface-expressed and functional. By analyses of chimeric human/mouse and human/bonobo receptors, bonobo receptor mutants, and the single nucleotide polymorphism database at NCBI, we identify an insertion/deletion variation in the third intracellular loop responsible for the intracellular retention and lack of function of the human ortholog. Genetic analyses of the 1000 genome database and the Inter99 cohort of 6,000 Danes establish the distribution of genotypes among ethnic groups, showing that the cell surface-expressed and functional variant is much more prevalent in the African population than in European and Asian populations and that this variant is partly linked with a stop codon early in the receptor sequence (rs6907580, amino acid position 57). In conclusion, our data solve a more than decade-old question of why the cloned human GPRC6A receptor is not cell surface-expressed and functional and provide a genetic framework to study human phenotypic traits in large genome sequencing projects linked with physiological measurement and biomarkers.
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Affiliation(s)
- Stine Jørgensen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Christian Theil Have
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christina Rye Underwood
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Lars Dan Johansen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Petrine Wellendorph
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Anette Prior Gjesing
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christinna V Jørgensen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Shi Quan
- BGI-Shenzhen, Shenzhen 518083, China
| | - Gao Rui
- BGI-Shenzhen, Shenzhen 518083, China
| | - Asuka Inoue
- the Laboratory of Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.,the Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology, Kawaguchi, Saitama 332-0012, Japan
| | - Allan Linneberg
- the Research Centre for Prevention and Health, Capital Region of Denmark, DK-2600 Glostrup, Denmark.,the Department of Clinical Experimental Research, Rigshospitalet, DK-2100 Copenhagen, Denmark, and.,the Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Niels Grarup
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Wang Jun
- BGI-Shenzhen, Shenzhen 518083, China
| | - Oluf Pedersen
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Torben Hansen
- the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark,
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