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Sridhar A, Khan D, Babu G, Irwin N, Gault VA, Flatt PR, Moffett CR. Chronic exposure to incretin metabolites GLP-1(9-36) and GIP(3-42) affect islet morphology and beta cell health in high fat fed mice. Peptides 2024; 178:171254. [PMID: 38815655 DOI: 10.1016/j.peptides.2024.171254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/24/2024] [Accepted: 05/27/2024] [Indexed: 06/01/2024]
Abstract
The incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are rapidly degraded by dipeptidyl peptidase-4 (DPP-4) to their major circulating metabolites GLP-1(9-36) and GIP(3-42). This study investigates the possible effects of these metabolites, and the equivalent exendin molecule Ex(9-39), on pancreatic islet morphology and constituent alpha and beta cells in high-fat diet (HFD) fed mice. Male Swiss TO-mice (6-8 weeks-old) were maintained on a HFD or normal diet (ND) for 4 months and then received twice-daily subcutaneous injections of GLP-1(9-36), GIP(3-42), Ex(9-39) (25 nmol/kg bw) or saline vehicle (0.9% (w/v) NaCl) over a 60-day period. Metabolic parameters were monitored and excised pancreatic tissues were used for immunohistochemical analysis. Body weight and assessed metabolic indices were not changed by peptide administration. GLP-1(9-36) significantly (p<0.001) increased islet density per mm2 tissue, that was decreased (p<0.05) by HFD. Islet, beta and alpha cell areas were increased (p<0.01) following HFD and subsequently reduced (p<0.01-p<0.001) by GIP(3-42) and Ex(9-39) treatment. While GLP-1(9-36) did not affect islet and beta cell areas in HFD mice, it significantly (p<0.01) decreased alpha cell area. Compared to ND and HFD mice, GIP(3-42) treatment significantly (p<0.05) increased beta cell proliferation. Whilst HFD increased (p<0.001) beta cell apoptosis, this was reduced (p<0.01-p<0.001) by both GLP-1(9-36) and GIP(3-42). These data indicate that the major circulating forms of GLP-1 and GIP, namely GLP-1(9-36) and GIP(3-42) previously considered largely inactive, may directly impact pancreatic morphology, with an important protective effect on beta cell health under conditions of beta cell stress.
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Affiliation(s)
- Ananyaa Sridhar
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK.
| | - Dawood Khan
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Gayathri Babu
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Victor A Gault
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Charlotte R Moffett
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
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2
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Gasbjerg LS, Rasmussen RS, Dragan A, Lindquist P, Melchiorsen JU, Stepniewski TM, Schiellerup S, Tordrup EK, Gadgaard S, Kizilkaya HS, Willems S, Zhong Y, Wang Y, Wright SC, Lauschke VM, Hartmann B, Holst JJ, Selent J, Rosenkilde MM. Altered desensitization and internalization patterns of rodent versus human glucose-dependent insulinotropic polypeptide (GIP) receptors. An important drug discovery challenge. Br J Pharmacol 2024. [PMID: 38952084 DOI: 10.1111/bph.16478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 04/10/2024] [Accepted: 05/06/2024] [Indexed: 07/03/2024] Open
Abstract
BACKGROUND AND PURPOSE The gut hormone glucose-dependent insulinotropic polypeptide (GIP) signals via the GIP receptor (GIPR), resulting in postprandial potentiation of glucose-stimulated insulin secretion. The translation of results from rodent studies to human studies has been challenged by the unexpected effects of GIPR-targeting compounds. We, therefore, investigated the variation between species, focusing on GIPR desensitization and the role of the receptor C-terminus. EXPERIMENTAL APPROACH The GIPR from humans, mice, rats, pigs, dogs and cats was studied in vitro for cognate ligand affinity, G protein activation (cAMP accumulation), recruitment of beta-arrestin and internalization. Variants of the mouse, rat and human GIPRs with swapped C-terminal tails were studied in parallel. KEY RESULTS The human GIPR is more prone to internalization than rodent GIPRs. Despite similar agonist affinities and potencies for Gαs activation, especially, the mouse GIPR shows reduced receptor desensitization, internalization and beta-arrestin recruitment. Using an enzyme-stabilized, long-acting GIP analogue, the species differences were even more pronounced. 'Tail-swapped' human, rat and mouse GIPRs were all fully functional in their Gαs coupling, and the mouse GIPR regained internalization and beta-arrestin 2 recruitment properties with the human tail. The human GIPR lost the ability to recruit beta-arrestin 2 when its own C-terminus was replaced by the rat or mouse tail. CONCLUSIONS AND IMPLICATIONS Desensitization of the human GIPR is dependent on the C-terminal tail. The species-dependent functionality of the C-terminal tail and the different species-dependent internalization patterns, especially between human and mouse GIPRs, are important factors influencing the preclinical evaluation of GIPR-targeting therapeutic compounds.
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Affiliation(s)
- Lærke Smidt Gasbjerg
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Syberg Rasmussen
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Adrian Dragan
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Lindquist
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Josefine Ulrikke Melchiorsen
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tomasz Maciej Stepniewski
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Research Institute and Pompeu Fabra University, Barcelona, Spain
- InterAx Biotech AG, Villigen, Switzerland
- Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Warsaw, Poland
| | - Sine Schiellerup
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Esther Karen Tordrup
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sarina Gadgaard
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Bainan Biotech, Copenhagen, Denmark
| | - Hüsün Sheyma Kizilkaya
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sabine Willems
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Yi Zhong
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yi Wang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Hangzhou, China
- National Key Laboratory of Chinese Medicine Modernization, Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing, China
| | - Shane C Wright
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Volker M Lauschke
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
- University of Tübingen, Tübingen, Germany
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Center for Basic Metabolic Research, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Research Institute and Pompeu Fabra University, Barcelona, Spain
| | - Mette Marie Rosenkilde
- Department of Biomedical Sciences, Faculty of Healthy and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Rosenkilde MM, Lindquist P, Kizilkaya HS, Gasbjerg LS. GIP-derived GIP receptor antagonists - a review of their role in GIP receptor pharmacology. Peptides 2024; 177:171212. [PMID: 38608836 DOI: 10.1016/j.peptides.2024.171212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 04/01/2024] [Accepted: 04/08/2024] [Indexed: 04/14/2024]
Abstract
Surprisingly, agonists, as well as antagonists of the glucose-dependent insulinotropic polypeptide receptor (GIPR), are currently being used or investigated as treatment options for type 2 diabetes and obesity - and both, when combined with glucagon-like peptide 1 receptor (GLP-1R) agonism, enhance GLP-1-induced glycemia and weight loss further. This paradox raises several questions regarding not only the mechanisms of actions of GIP but also the processes engaged during the activation of both the GIP and GLP-1 receptors. Here, we provide an overview of studies of the properties and actions of peptide-derived GIPR antagonists, focusing on GIP(3-30)NH2, a naturally occurring N- and C-terminal truncation of GIP(1-42). GIP(3-30)NH2 was the first GIPR antagonist administered to humans. GIP(3-30)NH2 and a few additional antagonists, like Pro3-GIP, have been used in both in vitro and in vivo studies to elucidate the molecular and cellular consequences of GIPR inhibition, desensitization, and internalization and, at a larger scale, the role of the GIP system in health and disease. We provide an overview of these studies combined with recent knowledge regarding the effects of naturally occurring variants of the GIPR system and species differences within the GIP system to enhance our understanding of the GIPR as a drug target.
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Affiliation(s)
- Mette Marie Rosenkilde
- Molecular and Translational Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Peter Lindquist
- Molecular and Translational Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hüsün Sheyma Kizilkaya
- Molecular and Translational Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lærke Smidt Gasbjerg
- Molecular and Translational Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Lafferty RA, Flatt PR, Irwin N. GLP-1/GIP analogues: potential impact in the landscape of obesity pharmacotherapy. Expert Opin Pharmacother 2023; 24:587-597. [PMID: 36927378 DOI: 10.1080/14656566.2023.2192865] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
INTRODUCTION : Obesity is recognised as a major healthcare challenge. Following years of slow progress in discovery of safe, effective therapies for weight management, recent approval of the glucagon-like peptide 1 receptor (GLP-1R) mimetics, liraglutide and semaglutide, for obesity has generated considerable excitement. It is anticipated these agents will pave the way for application of tirzepatide, a highly effective glucose-dependent insulinotropic polypeptide receptor (GIPR), GLP-1R co-agonist recently approved for management of type 2 diabetes mellitus. AREAS COVERED : Following promising weight loss in obese individuals in Phase III clinical trials, liraglutide and semaglutide were approved for weight management without diabetes. Tirzepatide has attained Fast Track designation for obesity management by the US Food and Drug Association. This narrative review summarises experimental, preclinical and clinical data for these agents and related GLP-1R/GIPR co-agonists, prioritising clinical research published within the last 10 years where possible. EXPERT OPINION : GLP-1R mimetics are often discontinued within 24-months, owing to gastrointestinal side-effects, meaning long-term application of these agents in obesity is questioned. Combined GIPR/GLP-1R agonism appears to induce fewer side-effects, indicating GLP-1R/GIPR co-agonists may be more suitable for enduring obesity management. After years of debate, this GIPR-biased GLP-1R/GIPR co-agonist highlights the therapeutic promise of including GIPR modulation for diabetes and obesity therapy.
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Affiliation(s)
- Ryan A Lafferty
- Diabetes Research Centre, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Peter R Flatt
- Diabetes Research Centre, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Nigel Irwin
- Diabetes Research Centre, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
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5
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Discovery of a potent GIPR peptide antagonist that is effective in rodent and human systems. Mol Metab 2022; 66:101638. [PMID: 36400403 PMCID: PMC9719863 DOI: 10.1016/j.molmet.2022.101638] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE Glucose-dependent insulinotropic polypeptide (GIP) is one of the two major incretin factors that regulate metabolic homeostasis. Genetic ablation of its receptor (GIPR) in mice confers protection against diet-induced obesity (DIO), while GIPR neutralizing antibodies produce additive weight reduction when combined with GLP-1R agonists in preclinical models and clinical trials. Conversely, GIPR agonists have been shown to promote weight loss in rodents, while dual GLP-1R/GIPR agonists have proven superior to GLP-1R monoagonists for weight reduction in clinical trials. We sought to develop a long-acting, specific GIPR peptide antagonist as a tool compound suitable for investigating GIPR pharmacology in both rodent and human systems. METHODS We report a structure-activity relationship of GIPR peptide antagonists based on the human and mouse GIP sequences with fatty acid-based protraction. We assessed these compounds in vitro, in vivo in DIO mice, and ex vivo in islets from human donors. RESULTS We report the discovery of a GIP(5-31) palmitoylated analogue, [Nα-Ac, L14, R18, E21] hGIP(5-31)-K11 (γE-C16), which potently inhibits in vitro GIP-mediated cAMP generation at both the hGIPR and mGIPR. In vivo, this peptide effectively blocks GIP-mediated reductions in glycemia in response to exogenous and endogenous GIP and displays a circulating pharmacokinetic profile amenable for once-daily dosing in rodents. Co-administration with the GLP-1R agonist semaglutide and this GIPR peptide antagonist potentiates weight loss compared to semaglutide alone. Finally, this antagonist inhibits GIP- but not GLP-1-stimulated insulin secretion in intact human islets. CONCLUSIONS Our work demonstrates the discovery of a potent, specific, and long-acting GIPR peptide antagonist that effectively blocks GIP action in vitro, ex vivo in human islets, and in vivo in mice while producing additive weight-loss when combined with a GLP-1R agonist in DIO mice.
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6
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Lindquist P, Gasbjerg LS, Mokrosinski J, Holst JJ, Hauser AS, Rosenkilde MM. The Location of Missense Variants in the Human GIP Gene Is Indicative for Natural Selection. Front Endocrinol (Lausanne) 2022; 13:891586. [PMID: 35846282 PMCID: PMC9277503 DOI: 10.3389/fendo.2022.891586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/04/2022] [Indexed: 11/16/2022] Open
Abstract
The intestinal hormone, glucose-dependent insulinotropic polypeptide (GIP), is involved in important physiological functions, including postprandial blood glucose homeostasis, bone remodeling, and lipid metabolism. While mutations leading to physiological changes can be identified in large-scale sequencing, no systematic investigation of GIP missense variants has been performed. Here, we identified 168 naturally occurring missense variants in the human GIP genes from three independent cohorts comprising ~720,000 individuals. We examined amino acid changing variants scattered across the pre-pro-GIP peptide using in silico effect predictions, which revealed that the sequence of the fully processed GIP hormone is more protected against mutations than the rest of the precursor protein. Thus, we observed a highly species-orthologous and population-specific conservation of the GIP peptide sequence, suggestive of evolutionary constraints to preserve the GIP peptide sequence. Elucidating the mutational landscape of GIP variants and how they affect the structural and functional architecture of GIP can aid future biological characterization and clinical translation.
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Affiliation(s)
- Peter Lindquist
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lærke Smidt Gasbjerg
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacek Mokrosinski
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, United States
| | - 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, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Sebastian Hauser
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Alexander Sebastian Hauser, ; Mette Marie Rosenkilde,
| | - Mette Marie Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Alexander Sebastian Hauser, ; Mette Marie Rosenkilde,
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7
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Associations between Postprandial Gut Hormones and Markers of Bone Remodeling. Nutrients 2021; 13:nu13093197. [PMID: 34579074 PMCID: PMC8467604 DOI: 10.3390/nu13093197] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/06/2021] [Accepted: 09/10/2021] [Indexed: 01/31/2023] Open
Abstract
Gut-derived hormones have been suggested to play a role in bone homeostasis following food intake, although the associations are highly complex and not fully understood. In a randomized, two-day cross-over study on 14 healthy individuals, we performed postprandial time-course studies to examine the associations of the bone remodeling markers carboxyl-terminal collagen type I crosslinks (CTX) and procollagen type 1 N-terminal propeptide (P1NP) with the gut hormones glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) using two different meal types-a standardized mixed meal (498 kcal) or a granola bar (260 kcal). Plasma concentrations of total GIP, total GLP-1, total PYY, CTX, and P1NP were measured up to 240 min after meal intake, and the incremental area under the curve (iAUC) for each marker was calculated. The iAUC of CTX and P1NP were used to assess associations with the iAUC of GIP, GLP-1, and PYY in linear mixed effect models adjusted for meal type. CTX was positively associated with GIP and GLP-1, and it was inversely associated with PYY (all p < 0.001). No associations of P1NP with GIP or GLP-1 and PYY were found. In conclusion, the postprandial responses of the gut hormones GIP, GLP-1, and PYY are associated with the bone resorption marker CTX, supporting a link between gut hormones and bone homeostasis following food intake.
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8
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Smit FX, van der Velden WJC, Kizilkaya HS, Nørskov A, Lückmann M, Hansen TN, Sparre-Ulrich AH, Qvotrup K, Frimurer TM, Rosenkilde MM. Investigating GIPR (ant)agonism: A structural analysis of GIP and its receptor. Structure 2021; 29:679-693.e6. [PMID: 33891864 DOI: 10.1016/j.str.2021.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 02/01/2021] [Accepted: 04/02/2021] [Indexed: 12/21/2022]
Abstract
The glucose-dependent insulinotropic polypeptide (GIP) is a 42-residue metabolic hormone that is actively being targeted for its regulatory role of glycemia and energy balance. Limited structural data of its receptor has made ligand design tedious. This study investigates the structure and function of the GIP receptor (GIPR), using a homology model based on the GLP-1 receptor. Molecular dynamics combined with in vitro mutational data were used to pinpoint residues involved in ligand binding and/or receptor activation. Significant differences in binding mode were identified for the naturally occurring agonists GIP(1-30)NH2 and GIP(1-42) compared with high potency antagonists GIP(3-30)NH2 and GIP(5-30)NH2. Residues R1832.60, R1902.67, and R3005.40 are shown to be key for activation of the GIPR, and evidence suggests that a disruption of the K293ECL2-E362ECL3 salt bridge by GIPR antagonists strongly reduces GIPR activation. Combinatorial use of these findings can benefit rational design of ligands targeting the GIPR.
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Affiliation(s)
- Florent X Smit
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200, Denmark; Section for Metabolic Receptology, Novo Nordisk Center for Basic Metabolic Research, University of Copenhagen, Copenhagen 2200, Denmark
| | - Wijnand J C van der Velden
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200, Denmark
| | - Hüsün S Kizilkaya
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200, Denmark
| | - Amalie Nørskov
- Department of Chemistry, Technical University of Denmark, Lyngby 2800, Denmark
| | - Michael Lückmann
- Section for Metabolic Receptology, Novo Nordisk Center for Basic Metabolic Research, University of Copenhagen, Copenhagen 2200, Denmark
| | - Tobias N Hansen
- Department of Chemistry, Technical University of Denmark, Lyngby 2800, Denmark
| | - Alexander H Sparre-Ulrich
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200, Denmark
| | - Katrine Qvotrup
- Department of Chemistry, Technical University of Denmark, Lyngby 2800, Denmark
| | - Thomas M Frimurer
- Section for Metabolic Receptology, Novo Nordisk Center for Basic Metabolic Research, University of Copenhagen, Copenhagen 2200, Denmark
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200, Denmark.
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9
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Boer GA, Hartmann B, Holst JJ. Pharmacokinetics of exogenous GIP(1-42) in C57Bl/6 mice; Extremely rapid degradation but marked variation between available assays. Peptides 2021; 136:170457. [PMID: 33245951 PMCID: PMC7883216 DOI: 10.1016/j.peptides.2020.170457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022]
Abstract
Like other peptide hormones, glucose-dependent insulinotropic polypeptide (GIP) is rapidly cleared from the circulation. Dipeptidyl peptidase-4 (DPP-4) is known to be involved. Information on the overall pharmacokinetics of GIP in rodents is, however, lacking. We investigated the pharmacokinetics of exogenous GIP after intravenous, subcutaneous and intraperitoneal injection with and without DPP-4 inhibition in conscious female C57Bl/6 mice. Secondly, we compared total and intact GIP levels measured by an in-house RIA and commercially available ELISA kits to determine the suitability of these methods for in vivo and in vitro measurements. GIP half-life following intravenous injection amounted to 93 ± 2 s, which was extended to 5 ± 0.6 min by inhibition of DPP-4. Intact GIP levels following subcutaneous and intraperitoneal GIP administration were approximately 15 % of total GIP. The area under the curve of intact GIP (GIP exposure) following GIP injection was significantly increased by DPP-4 inhibition, whereas total GIP levels remained unchanged. We found significant variation between measurements of total, but not intact GIP performed with our in-house RIA and ELISAs in samples obtained after in vivo administration of GIP. Different preanalytical sample preparation (EDTA plasma, heparin plasma, assay buffer and PBS) significantly influenced results for all ELISA kits used. Thus, in experiments involving exogenous GIP(1-42) administration in mice, it is important to consider that this will result in a very low ratio of intact:total peptide but co-administration of a DPP-4 inhibitor greatly elevates this ratio. Furthermore, for comparison of GIP levels, it is essential to maintain uniformity concerning assay methodology and sample preparation.
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Affiliation(s)
- Geke Aline Boer
- NNF 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.
| | - Bolette Hartmann
- NNF 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.
| | - Jens Juul Holst
- NNF 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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10
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van der Velden WJC, Heitman LH, Rosenkilde MM. Perspective: Implications of Ligand-Receptor Binding Kinetics for Therapeutic Targeting of G Protein-Coupled Receptors. ACS Pharmacol Transl Sci 2020; 3:179-189. [PMID: 32296761 DOI: 10.1021/acsptsci.0c00012] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Indexed: 12/16/2022]
Abstract
The concept of ligand-receptor binding kinetics has been broadly applied in drug development pipelines focusing on G protein-coupled receptors (GPCRs). The ligand residence time (RT) for a receptor describes how long a ligand-receptor complex exists, and is defined as the reciprocal of the dissociation rate constant (k off). RT has turned out to be a valuable parameter for GPCR researchers focusing on drug development as a good predictor of in vivo efficacy. The positive correlation between RT and in vivo efficacy has been established for several drugs targeting class A GPCRs (e.g., the neurokinin-1 receptor (NK1R), the β2 adrenergic receptor (β2AR), and the muscarinic 3 receptor (M3R)) and for drugs targeting class B1 (e.g., the glucagon-like peptide 1 receptor (GLP-1R)). Recently, the association rate constant (k on) has gained similar attention as another parameter affecting in vivo efficacy. In the current perspective, we address the importance of studying ligand-receptor binding kinetics for therapeutic targeting of GPCRs, with an emphasis on how binding kinetics can be altered by subtle molecular changes in the ligands and/or the receptors and how such changes affect treatment outcome. Moreover, we speculate on the impact of binding kinetic parameters for functional selectivity and sustained receptor signaling from endosomal compartments; phenomena that have gained increasing interest in attempts to improve therapeutic targeting of GPCRs.
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Affiliation(s)
- Wijnand J C van der Velden
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK 2200, Denmark
| | - Laura H Heitman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Leiden 2333 CC, The Netherlands
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK 2200, Denmark
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11
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Nauck MA, Holle H, Kahle M, Tytko A, Deacon CF, Holst JJ, Meier JJ. No evidence of tachyphylaxis for insulinotropic actions of glucose-dependent insulinotropic polypeptide (GIP) in subjects with type 2 diabetes, their first-degree relatives, or in healthy subjects. Peptides 2020; 125:170176. [PMID: 31669136 DOI: 10.1016/j.peptides.2019.170176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/12/2019] [Accepted: 10/14/2019] [Indexed: 01/10/2023]
Abstract
BACKGROUND, AIMS In patients with type 2 diabetes, the lost insulinotropic effect of the incretin hormone glucose-dependent insulinotropic polypeptide (GIP) is more apparent after continuous versus bolus administration. To test whether the difference might be explained by rapid tachyphylaxis in response to elevated concentrations of GIP, and whether patients with type 2 diabetes and their relatives are more susceptible to tachyphylaxis than healthy subjects. PATIENTS AND METHODS In a two-way crossover design, insulinotropic responses to repeated bolus injection (50 pmol/kg body weight at 30 and 120 min) and continuous infusion of GIP (2 pmol.kg-1.min-1 from 30 to 180 min) under hyperglycaemic clamp conditions (8.5 mmol/l) was compared in age- gender- and weight-matched patients with type 2 diabetes, first degree relatives of such patients, and healthy subjects. RESULTS Insulin secretory responses to the first and second GIP bolus were not significantly different in any of the subject groups. Subjects with type 2 diabetes had a significant relative impairment versus healthy subjects with continuous (C-peptide, -13.2 %, p < 0.05), but not with repeated bolus administration of GIP (+11.1 %, n.s.). First-degree relatives tended to hyper-secrete insulin with bolus or continuous administrations of GIP. CONCLUSIONS Rapid tachyphylaxis in response to continuous exposure to slightly supraphysiological concentrations of GIP does not explain the reduced insulinotropic response to GIP infusions in patients with type 2 diabetes or their first-degree relatives.
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Affiliation(s)
- M A Nauck
- Diabeteszentrum Bad Lauterberg, Bad Lauterberg im Harz, Germany; Diabetes Center Bochum-Hattingen, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.
| | - H Holle
- Diabeteszentrum Bad Lauterberg, Bad Lauterberg im Harz, Germany
| | - M Kahle
- Diabeteszentrum Bad Lauterberg, Bad Lauterberg im Harz, Germany; Diabetes Center Bochum-Hattingen, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
| | - A Tytko
- Diabeteszentrum Bad Lauterberg, Bad Lauterberg im Harz, Germany
| | - C F Deacon
- Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - J J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - J J Meier
- Diabetes Center Bochum-Hattingen, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
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12
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Christensen MB, Gasbjerg LS, Heimbürger SM, Stensen S, Vilsbøll T, Knop FK. GIP's involvement in the pathophysiology of type 2 diabetes. Peptides 2020; 125:170178. [PMID: 31682875 DOI: 10.1016/j.peptides.2019.170178] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 10/17/2019] [Accepted: 10/17/2019] [Indexed: 02/06/2023]
Abstract
During the past four decades derangements in glucose-dependent insulinotropic polypeptide (GIP) biology has been viewed upon as contributing factors to various parts of the pathophysiology type 2 diabetes. This overview outlines and discusses the impaired insulin responses to GIP as well as the effect of GIP on glucagon secretion and the potential involvement of GIP in the obesity and bone disease associated with type 2 diabetes. As outlined in this review, it is unlikely that the impaired insulinotropic effect of GIP occurs as a primary event in the development of type 2 diabetes, but rather develops once the diabetic state is present and beta cells are unable to maintain normoglycemia. In various models, GIP has effects on glucagon secretion, bone and lipid homeostasis, but whether these effects contribute substantially to the pathophysiology of type 2 diabetes is at present controversial. The review also discusses the substantial uncertainty surrounding the translation of preclinical data relating to the GIP system and outline future research directions.
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Affiliation(s)
- Mikkel B Christensen
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Lærke S Gasbjerg
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Biomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sebastian M Heimbürger
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Signe Stensen
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Biomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tina Vilsbøll
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Steno Diabetes Center Copenhagen, Gentofte Hospital, Copenhagen, Denmark
| | - Filip K Knop
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Steno Diabetes Center Copenhagen, Gentofte Hospital, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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Heimbürger SM, Bergmann NC, Augustin R, Gasbjerg LS, Christensen MB, Knop FK. Glucose-dependent insulinotropic polypeptide (GIP) and cardiovascular disease. Peptides 2020; 125:170174. [PMID: 31689454 DOI: 10.1016/j.peptides.2019.170174] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/09/2019] [Accepted: 10/10/2019] [Indexed: 12/20/2022]
Abstract
Accumulating evidence suggests that glucose-dependent insulinotropic polypeptide (GIP) in addition to its involvement in type 2 diabetic pathophysiology may be involved in the development of obesity and the pathogenesis of cardiovascular disease. In this review, we outline recent preclinical and clinical cardiovascular-related discoveries about GIP. These include chronotropic and blood pressure-lowering effects of GIP. Furthermore, GIP has been suggested to control vasodilation via secretion of nitric oxide, and vascular leukocyte adhesion and inflammation via expression and secretion of endothelin 1. Also, GIP seems to regulate circulating lipids via effects on adipose tissue uptake and metabolism of lipids. Lastly, we discuss how dysmetabolic conditions such as obesity and type 2 diabetes may shift the actions of GIP in an atherogenic direction, and we provide a perspective on the therapeutic potential of GIP receptor agonism and antagonism in cardiovascular diseases. We conclude that GIP actions may have implications for the development of cardiovascular disease, but also that the potential of GIP-based drugs for the treatment of cardiovascular disease currently is uncertain.
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Affiliation(s)
- Sebastian M Heimbürger
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Steno Diabetes Center Copenhagen, Gentofte, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Natasha C Bergmann
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | - Robert Augustin
- Department of Cardiometabolic Diseases Research, Boehringer Ingelheim GmbH & CoKG, Biberach, Germany
| | - Lærke S Gasbjerg
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Biomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel B Christensen
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip K Knop
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Steno Diabetes Center Copenhagen, Gentofte, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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14
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Irwin N, Gault VA, O'Harte FPM, Flatt PR. Blockade of gastric inhibitory polypeptide (GIP) action as a novel means of countering insulin resistance in the treatment of obesity-diabetes. Peptides 2020; 125:170203. [PMID: 31733230 DOI: 10.1016/j.peptides.2019.170203] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/21/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022]
Abstract
Gastric inhibitory polypeptide (GIP) is a 42 amino acid hormone secreted from intestinal K-cells in response to nutrient ingestion. Despite a recognised physiological role for GIP as an insulin secretagogue to control postprandial blood glucose levels, growing evidence reveals important actions of GIP on adipocytes and promotion of fat deposition in tissues. As such, blockade of GIP receptor (GIPR) action has been proposed as a means to counter insulin resistance, and improve metabolic status in obesity and related diabetes. In agreement with this, numerous independent observations in animal models support important therapeutic applications of GIPR antagonists in obesity-diabetes. Sustained administration of peptide-based GIPR inhibitors, low molecular weight GIPR antagonists, GIPR neutralising antibodies as well as genetic knockout of GIPR's or vaccination against GIP all demonstrate amelioration of insulin resistance and reduced body weight gain in response to high fat feeding. These observations were consistently associated with decreased accumulation of lipids in peripheral tissues, thereby alleviating insulin resistance. Although the impact of prolonged GIPR inhibition on bone turnover still needs to be determined, evidence to date indicates that GIPR antagonists represent an exciting novel treatment option for obesity-diabetes.
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Affiliation(s)
- Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK.
| | - Victor A Gault
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
| | - Finbarr P M O'Harte
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK
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15
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Gabe MBN, van der Velden WJC, Smit FX, Gasbjerg LS, Rosenkilde MM. Molecular interactions of full-length and truncated GIP peptides with the GIP receptor - A comprehensive review. Peptides 2020; 125:170224. [PMID: 31809770 DOI: 10.1016/j.peptides.2019.170224] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/25/2019] [Accepted: 11/27/2019] [Indexed: 12/17/2022]
Abstract
Enzymatic cleavage of endogenous peptides is a commonly used principle to initiate, modulate and terminate action for instance among cytokines and peptide hormones. The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), and the related hormone glucagon-like peptide-2 (GLP-2) are all rapidly N-terminally truncated with severe loss of intrinsic activity. The most abundant circulating form of full length GIP(1-42) is GIP(3-42) (a dipeptidyl peptidase-4 (DPP-4) product). GIP(1-30)NH2 is another active form resulting from prohormone convertase 2 (PC2) cleavage of proGIP. Like GIP(1-42), GIP(1-30)NH2 is a substrate for DPP-4 generating GIP(3-30)NH2 which, compared to GIP(3-42), binds with higher affinity and very efficiently inhibits GIP receptor (GIPR) activity with no intrinsic activity. Here, we review the action of these four and multiple other N- and C-terminally truncated forms of GIP with an emphasis on molecular pharmacology, i.e. ligand binding, subsequent receptor activation and desensitization. Our overall conclusion is that the N-terminus is essential for receptor activation as GIP N-terminal truncation leads to decreased/lost intrinsic activity and antagonism (similar to GLP-1 and GLP-2), whereas the C-terminal extension of GIP(1-42), as compared to GLP-1, GLP-2 and glucagon (29-33 amino acids), has no apparent impact on the GIPR in vitro, but may play a role for other properties such as stability and tissue distribution. A deeper understanding of the molecular interaction of naturally occurring and designed GIP-based peptides, and their impact in vivo, may contribute to a future therapeutic targeting of the GIP system - either with agonists or with antagonists, or both.
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Affiliation(s)
- Maria Buur Nordskov Gabe
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Wijnand J C van der Velden
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Florent Xavier Smit
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Lærke Smidt Gasbjerg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | - Mette Marie Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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16
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Holst JJ, Albrechtsen NJW, Rosenkilde MM, Deacon CF. Physiology of the Incretin Hormones,
GIP
and
GLP
‐1—Regulation of Release and Posttranslational Modifications. Compr Physiol 2019; 9:1339-1381. [DOI: 10.1002/cphy.c180013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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17
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Perry RA, Craig SL, Ng MT, Gault VA, Flatt PR, Irwin N. Characterisation of Glucose-Dependent Insulinotropic Polypeptide Receptor Antagonists in Rodent Pancreatic Beta Cells and Mice. CLINICAL MEDICINE INSIGHTS-ENDOCRINOLOGY AND DIABETES 2019; 12:1179551419875453. [PMID: 31548798 PMCID: PMC6743192 DOI: 10.1177/1179551419875453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 08/21/2019] [Indexed: 12/18/2022]
Abstract
Hypersecretion and alterations in the biological activity of the incretin
hormone, glucose-dependent insulinotropic polypeptide (GIP), have been
postulated as contributing factors in the development of obesity-related
diabetes. However, recent studies also point to weight-reducing effects of GIP
receptor activation. Therefore, generating precise experimental tools, such as
specific and effective GIP receptor (GIPR) antagonists, is of key significance
to better understand GIP physiology. Thus, the primary aim of the current study
was to uncover improved GIPR antagonists for use in rodent studies, using human
and mouse GIP sequences with N- and C-terminal deletions. Initial in
vitro studies revealed that the GIPR agonists, human (h) GIP(1-42),
hGIP(1-30) and mouse (m) GIP(1-30), stimulated (P < 0.01 to
P < 0.001) insulin secretion from rat BRIN-BD11 cells.
Analysis of insulin secretory effects of the N- and C-terminally cleaved GIP
peptides, including hGIP(3-30), mGIP(3-30), h(Pro3)GIP(3-30),
hGIP(5-30), hGIP(3-42) and hGIP(5-42), revealed that these peptides did not
modulate insulin secretion. More pertinently, only hGIP(3-30), mGIP(3-30) and
h(Pro3)GIP(3-30) were able to significantly (P
< 0.01 to P < 0.001) inhibit hGIP(1-42)-stimulated
insulin secretion. The human-derived GIPR agonist sequences, hGIP(1-42) and
hGIP(1-30), reduced (P < 0.05) glucose levels in mice
following conjoint injection with glucose, but mGIP(1-30) was ineffective. None
of the N- and C-terminally cleaved GIP peptides affected glucose homeostasis
when injected alone with glucose. However, hGIP(5-30) and mGIP(3-30)
significantly (P < 0.05 to P < 0.01)
impaired the glucose-lowering action of hGIP(1-42). Further evaluation of these
most effective sequences demonstrated that mGIP(3-30), but not hGIP(5-30),
effectively prevented GIP-induced elevations of plasma insulin concentrations.
These data highlight, for the first time, that mGIP(3-30) represents an
effective molecule to inhibit GIPR activity in mice.
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Affiliation(s)
- R A Perry
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, UK
| | - S L Craig
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, UK
| | - M T Ng
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, UK
| | - V A Gault
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, UK
| | - P R Flatt
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, UK
| | - N Irwin
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, UK
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18
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Human GIP(3-30)NH 2 inhibits G protein-dependent as well as G protein-independent signaling and is selective for the GIP receptor with high-affinity binding to primate but not rodent GIP receptors. Biochem Pharmacol 2018; 150:97-107. [PMID: 29378179 DOI: 10.1016/j.bcp.2018.01.040] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 01/22/2018] [Indexed: 12/21/2022]
Abstract
GIP(3-30)NH2 is a high affinity antagonist of the GIP receptor (GIPR) in humans inhibiting insulin secretion via G protein-dependent pathways. However, its ability to inhibit G protein-independent signaling is unknown. Here we determine its action on arrestin-recruitment and receptor internalization in recombinant cells. As GIP is adipogenic, we evaluate the inhibitory actions of GIP(3-30)NH2 in human adipocytes. Finally, we determine the receptor selectivity of GIP(3-30)NH2 among other human and animal GPCRs. cAMP accumulation and β-arrestin 1 and 2 recruitment were studied in transiently transfected HEK293 cells and real-time internalization in transiently transfected HEK293A and in HEK293A β-arrestin 1 and 2 knockout cells. Furthermore, human subcutaneous adipocytes were assessed for cAMP accumulation following ligand stimulation. Competition binding was examined in transiently transfected COS-7 cells using human 125I-GIP(3-30)NH2. The selectivity of human GIP(3-30)NH2 was examined by testing for agonistic and antagonistic properties on 62 human GPCRs. Human GIP(3-30)NH2 inhibited GIP(1-42)-induced cAMP and β-arrestin 1 and 2 recruitment on the human GIPR and Schild plot analysis showed competitive antagonism with a pA2 and Hill slope of 16.8 nM and 1.11 ± 0.02 in cAMP, 10.6 nM and 1.15 ± 0.05 in β-arrestin 1 recruitment, and 10.2 nM and 1.06 ± 0.05 in β-arrestin 2 recruitment. Efficient internalization of the GIPR was dependent on the presence of either β-arrestin 1 or 2. Moreover, GIP(3-30)NH2 inhibited GIP(1-42)-induced internalization in a concentration-dependent manner and notably also inhibited GIP-mediated signaling in human subcutaneous adipocytes. Finally, the antagonist was established as GIPR selective among 62 human GPCRs being species-specific with high affinity binding to the human and non-human primate (Macaca fascicularis) GIPRs, and low affinity binding to the rat and mouse GIPRs (Kd values of 2.0, 2.5, 31.6 and 100 nM, respectively). In conclusion, human GIP(3-30)NH2 is a selective and species-specific GIPR antagonist with broad inhibition of signaling and internalization in transfected cells as well as in human adipocytes.
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19
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Gasbjerg LS, Gabe MBN, Hartmann B, Christensen MB, Knop FK, Holst JJ, Rosenkilde MM. Glucose-dependent insulinotropic polypeptide (GIP) receptor antagonists as anti-diabetic agents. Peptides 2018; 100:173-181. [PMID: 29412817 DOI: 10.1016/j.peptides.2017.11.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 11/27/2017] [Accepted: 11/28/2017] [Indexed: 01/07/2023]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) is an intestinal hormone with a broad range of physiological actions. In the postprandial state, the hormone stimulates insulin secretion and during eu- and hypoglycemia, it stimulates glucagon secretion. In addition, GIP increases triacylglycerol (TAG) uptake in adipose tissue and decreases bone resorption. However, the importance of these actions in humans are not clearly understood as a specific GIP receptor (GIPR) antagonist - an essential tool to study GIP physiology - has been missing. Several different GIPR antagonists have been identified comprising both peptides, vaccines against GIP, GIP antibodies or antibodies against the GIPR. However, most of these have only been tested in rodents. In vitro, N- and C-terminally truncated GIP variants are potent and efficacious GIPR antagonists. Recently, GIP(3-30)NH2, a naturally occurring peptide, was shown to block the GIPR in humans and decrease GIP-induced insulin secretion as well as adipose tissue blood flow and TAG uptake. So far, there are no studies with a GIPR antagonist in patients with type 2 diabetes (T2D), but because the elevations in fasting plasma glucagon and paradoxical postprandial glucagon excursions, seen in patients with T2D, are aggravated by GIP, a GIPR antagonist could partly alleviate this and possibly improve the fasting and postprandial glycemia. Since the majority of patients with T2D are overweight, inhibition of GIP-induced fat deposition may be beneficial as well. Here we summarize the studies of GIPR antagonists and discuss the therapeutic potential of the GIP system in humans.
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Affiliation(s)
- Lærke Smidt Gasbjerg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark.
| | - Maria Buur Nordskov Gabe
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel Bring Christensen
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Filip Krag Knop
- NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Clinical Medicine, 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; NNF Center for Basic Metabolic Research, 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; NNF Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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20
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Gasbjerg LS, Christensen MB, Hartmann B, Lanng AR, Sparre-Ulrich AH, Gabe MBN, Dela F, Vilsbøll T, Holst JJ, Rosenkilde MM, Knop FK. GIP(3-30)NH 2 is an efficacious GIP receptor antagonist in humans: a randomised, double-blinded, placebo-controlled, crossover study. Diabetologia 2018; 61:413-423. [PMID: 28948296 DOI: 10.1007/s00125-017-4447-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 08/09/2017] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone secreted postprandially from enteroendocrine K cells, but despite therapeutically interesting effects, GIP physiology in humans remains incompletely understood. Progress in this field could be facilitated by a suitable GIP receptor antagonist. For the first time in humans, we investigated the antagonistic properties of the naturally occurring GIP(3-30)NH2 in in vivo and in in vitro receptor studies. METHODS In transiently transfected COS-7 cells, GIP(3-30)NH2 was evaluated with homologous receptor binding and receptor activation (cAMP accumulation) studies at the glucagon-like peptide 1 (GLP-1), glucagon-like peptide-2 (GLP-2), glucagon, secretin and growth hormone-releasing hormone (GHRH) receptors. Ten healthy men (eligibility criteria: age 20-30 years, HbA1c less than 6.5% [48 mmol/mol] and fasting plasma glucose [FPG] less than 7 mmol/l) were included in the clinical study. Data were collected as plasma and serum samples from a cubital vein cannula. As primary outcome, insulin secretion and glucose requirements were evaluated together with in a randomised, four-period, crossover design by infusing GIP(3-30)NH2 (800 pmol kg-1 min-1), GIP (1.5 pmol kg-1 min-1), a combination of these or placebo during hyperglycaemic clamp experiments. The content of the infusions were blinded to the study participants and experimental personnel. No study participants dropped out. RESULTS GIP(3-30)NH2 neither bound, stimulated nor antagonised a series of related receptors in vitro. The elimination plasma half-life of GIP(3-30)NH2 in humans was 7.6 ± 1.4 min. Markedly larger amounts of glucose were required to maintain the clamp during GIP infusion compared with the other days. GIP-induced insulin secretion was reduced by 82% (p < 0.0001) during co-infusion with GIP(3-30)NH2, and the need for glucose was reduced to placebo levels. There were no effects of GIP(3-30)NH2 alone or of GIP with or without GIP(3-30)NH2 on plasma glucagon, GLP-1, somatostatin, triacylglycerols, cholesterol, glycerol or NEFA. GIP(3-30)NH2 administration was well tolerated and without side effects. CONCLUSIONS/INTERPRETATION We conclude that GIP(3-30)NH2 is an efficacious and specific GIP receptor antagonist in humans suitable for studies of GIP physiology and pathophysiology. TRIAL REGISTRATION ClinicalTrials.gov registration no. NCT02747472. FUNDING The study was funded by Gangstedfonden, the European Foundation for the Study of Diabetes, and Aase og Ejnar Danielsens fond.
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Affiliation(s)
- Lærke S Gasbjerg
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Kildegårdsvej 28, 2900, Hellerup, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel B Christensen
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Kildegårdsvej 28, 2900, Hellerup, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Amalie R Lanng
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Kildegårdsvej 28, 2900, Hellerup, Denmark
| | - Alexander H Sparre-Ulrich
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maria B N Gabe
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Flemming Dela
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Geriatrics, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Tina Vilsbøll
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Kildegårdsvej 28, 2900, Hellerup, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Steno Diabetes Center Copenhagen, University of Copenhagen, Gentofte, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette M Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip K Knop
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Kildegårdsvej 28, 2900, Hellerup, Denmark.
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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21
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Hosoda Y, Okahara F, Mori T, Deguchi J, Ota N, Osaki N, Shimotoyodome A. Dietary steamed wheat bran increases postprandial fat oxidation in association with a reduced blood glucose-dependent insulinotropic polypeptide response in mice. Food Nutr Res 2017; 61:1361778. [PMID: 28970776 PMCID: PMC5614337 DOI: 10.1080/16546628.2017.1361778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 07/19/2017] [Indexed: 10/25/2022] Open
Abstract
Obesity is a global epidemic associated with a higher risk of cardiovascular disease and metabolic disorders, such as type 2 diabetes. Previous studies demonstrated that chronic feeding of steamed wheat bran (WB) decreases obesity. To clarify the underlying mechanism and the responsible component for the anti-obesity effects of steamed WB, we investigated the effects of dietary steamed WB and arabinoxylan on postprandial energy metabolism and blood variables. Overnight-fasted male C57BL/6J mice were fed an isocaloric diet with or without steamed WB (30%). Energy metabolism was evaluated using an indirect calorimeter, and plasma glucose, insulin, and glucose-dependent insulinotropic polypeptide (GIP) levels were measured for 120 min after feeding. We similarly investigated the effect of arabinoxylan, a major component of steamed WB. Mice fed the WB diet had higher postprandial fat oxidation and a lower blood GIP response compared with mice fed the control diet. Mice fed the arabinoxylan diet exhibited a dose-dependent postprandial blood GIP response; increasing the arabinoxylan content in the diet led to a lower postprandial blood GIP response. The arabinoxylan-fed mice also had higher fat oxidation and energy expenditure compared with the control mice. In conclusion, the findings of the present study revealed that dietary steamed WB increases fat oxidation in mice. Increased fat oxidation may have a significant role in the anti-obesity effects of steamed WB. The postprandial effects of steamed WB are due to arabinoxylan, a major component of WB. The reduction of the postprandial blood GIP response may be responsible for the increase in postprandial fat utilization after feeding on a diet containing steamed WB and arabinoxylan.
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Affiliation(s)
- Yayoi Hosoda
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan
| | - Fumiaki Okahara
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan
| | - Takuya Mori
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan
| | - Jun Deguchi
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan
| | - Noriyasu Ota
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan
| | - Noriko Osaki
- Biological Science Laboratories, Kao Corporation, Tochigi, Japan
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22
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Sparre-Ulrich A, Gabe M, Gasbjerg L, Christiansen C, Svendsen B, Hartmann B, Holst J, Rosenkilde M. GIP(3–30)NH2 is a potent competitive antagonist of the GIP receptor and effectively inhibits GIP-mediated insulin, glucagon, and somatostatin release. Biochem Pharmacol 2017; 131:78-88. [DOI: 10.1016/j.bcp.2017.02.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 02/14/2017] [Indexed: 12/31/2022]
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23
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Sekar R, Singh K, Arokiaraj AWR, Chow BKC. Pharmacological Actions of Glucagon-Like Peptide-1, Gastric Inhibitory Polypeptide, and Glucagon. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 326:279-341. [PMID: 27572131 DOI: 10.1016/bs.ircmb.2016.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Glucagon family of peptide hormones is a group of structurally related brain-gut peptides that exert their pleiotropic actions through interactions with unique members of class B1 G protein-coupled receptors (GPCRs). They are key regulators of hormonal homeostasis and are important drug targets for metabolic disorders such as type-2 diabetes mellitus (T2DM), obesity, and dysregulations of the nervous systems such as migraine, anxiety, depression, neurodegeneration, psychiatric disorders, and cardiovascular diseases. The current review aims to provide a detailed overview of the current understanding of the pharmacological actions and therapeutic advances of three members within this family including glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), and glucagon.
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Affiliation(s)
- R Sekar
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - K Singh
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - A W R Arokiaraj
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - B K C Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong, China.
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24
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Finan B, Müller TD, Clemmensen C, Perez-Tilve D, DiMarchi RD, Tschöp MH. Reappraisal of GIP Pharmacology for Metabolic Diseases. Trends Mol Med 2016; 22:359-376. [DOI: 10.1016/j.molmed.2016.03.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 12/31/2022]
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25
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Hansen LS, Sparre-Ulrich AH, Christensen M, Knop FK, Hartmann B, Holst JJ, Rosenkilde MM. N-terminally and C-terminally truncated forms of glucose-dependent insulinotropic polypeptide are high-affinity competitive antagonists of the human GIP receptor. Br J Pharmacol 2016; 173:826-38. [PMID: 26572091 PMCID: PMC4761099 DOI: 10.1111/bph.13384] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 10/13/2015] [Accepted: 10/16/2015] [Indexed: 12/25/2022] Open
Abstract
Background and Purpose Glucose‐dependent insulinotropic polypeptide (GIP) affects lipid, bone and glucose homeostasis. High‐affinity ligands for the GIP receptor are needed to elucidate the physiological functions and pharmacological potential of GIP in vivo. GIP(1–30)NH2 is a naturally occurring truncation of GIP(1–42). Here, we have characterized eight N‐terminal truncations of human GIP(1–30)NH2. Experimental Approach COS‐7 cells were transiently transfected with human GIP receptors and assessed for cAMP accumulation upon ligand stimulation or competition binding with 125I‐labelled GIP(1–42), GIP(1–30)NH2, GIP(2–30)NH2 or GIP(3–30)NH2. Key Results GIP(1–30)NH2 displaced 125I‐GIP(1–42) as effectively as GIP(1–42) (Ki 0.75 nM), whereas the eight truncations displayed lower affinities (Ki 2.3–347 nM) with highest affinities for GIP(3–30)NH2 and GIP(5–30)NH2 (5–30)NH2. Only GIP(1–30)NH2 (Emax 100% of GIP(1–42)) and GIP(2–30)NH2 (Emax 20%) were agonists. GIP(2‐ to 9–30)NH2 displayed antagonism (IC50 12–450 nM) and Schild plot analyses identified GIP(3–30)NH2 and GIP(5–30)NH2 as competitive antagonists (Ki 15 nM). GIP(3–30) NH2 was a 26‐fold more potent antagonist than GIP(3–42). Binding studies with agonist (125I‐GIP(1–30)NH2), partial agonist (125I‐GIP(2–30)NH2) and competitive antagonist (125I‐GIP(3–30)NH2) revealed distinct receptor conformations for these three ligand classes. Conclusions and Implications The N‐terminus is crucial for GIP agonist activity. Removal of the C‐terminus of the endogenous GIP(3–42) creates another naturally occurring, more potent, antagonist GIP(3–30)NH2, which like GIP(5–30)NH2, was a high‐affinity competitive antagonist. These peptides may be suitable tools for basic GIP research and future pharmacological interventions.
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Affiliation(s)
- L S Hansen
- Department of Neuroscience and Pharmacology, 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.,Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - A H Sparre-Ulrich
- Department of Neuroscience and Pharmacology, 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
| | - M Christensen
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - F K Knop
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - B Hartmann
- NNF Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - J J Holst
- NNF Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - M M Rosenkilde
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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26
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Sparre-Ulrich AH, Hansen LS, Svendsen B, Christensen M, Knop FK, Hartmann B, Holst JJ, Rosenkilde MM. Species-specific action of (Pro3)GIP - a full agonist at human GIP receptors, but a partial agonist and competitive antagonist at rat and mouse GIP receptors. Br J Pharmacol 2015; 173:27-38. [PMID: 26359804 PMCID: PMC4737396 DOI: 10.1111/bph.13323] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/23/2015] [Accepted: 09/02/2015] [Indexed: 12/14/2022] Open
Abstract
Background and Purpose Specific, high potency receptor antagonists are valuable tools when evaluating animal and human physiology. Within the glucose‐dependent, insulinotropic polypeptide (GIP) system, considerable attention has been given to the presumed GIP receptor antagonist, (Pro3)GIP, and its effect in murine studies. We conducted a pharmacological analysis of this ligand including interspecies differences between the rodent and human GIP system. Experimental Approach Transiently transfected COS‐7 cells were assessed for cAMP accumulation upon ligand stimulation and assayed in competition binding using 125I‐human GIP. Using isolated perfused pancreata both from wild type and GIP receptor‐deficient rodents, insulin‐releasing, glucagon‐releasing and somatostatin‐releasing properties in response to species‐specific GIP and (Pro3)GIP analogues were evaluated. Key Results Human (Pro3)GIP is a full agonist at human GIP receptors with similar efficacy (Emax) for cAMP production as human GIP, while both rat and mouse(Pro3)GIP were partial agonists on their corresponding receptors. Rodent GIPs are more potent and efficacious at their receptors than human GIP. In perfused pancreata in the presence of 7 mM glucose, both rodent (Pro3)GIP analogues induced modest insulin, glucagon and somatostatin secretion, corresponding to the partial agonist activities observed in cAMP production. Conclusions and Implications When evaluating new compounds, it is important to consider interspecies differences both at the receptor and ligand level. Thus, in rodent models, human GIP is a comparatively weak partial agonist. Human (Pro3)GIP was not an antagonist at human GIP receptors, so there is still a need for a potent antagonist in order to elucidate the physiology of human GIP.
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Affiliation(s)
- A H Sparre-Ulrich
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Copenhagen, Denmark
| | - L S Hansen
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.,NNF Center for Basic Metabolic Research, Copenhagen, Denmark.,Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - B Svendsen
- NNF Center for Basic Metabolic Research, Copenhagen, Denmark
| | - M Christensen
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - F K Knop
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - B Hartmann
- NNF Center for Basic Metabolic Research, Copenhagen, Denmark.,Department of Biomedical Sciences Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - J J Holst
- NNF Center for Basic Metabolic Research, Copenhagen, Denmark.,Department of Biomedical Sciences Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - M M Rosenkilde
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
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27
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Abstract
Dipeptidyl peptidase-4 (DPP4) is a widely expressed enzyme transducing actions through an anchored transmembrane molecule and a soluble circulating protein. Both membrane-associated and soluble DPP4 exert catalytic activity, cleaving proteins containing a position 2 alanine or proline. DPP4-mediated enzymatic cleavage alternatively inactivates peptides or generates new bioactive moieties that may exert competing or novel activities. The widespread use of selective DPP4 inhibitors for the treatment of type 2 diabetes has heightened interest in the molecular mechanisms through which DPP4 inhibitors exert their pleiotropic actions. Here we review the biology of DPP4 with a focus on: 1) identification of pharmacological vs physiological DPP4 substrates; and 2) elucidation of mechanisms of actions of DPP4 in studies employing genetic elimination or chemical reduction of DPP4 activity. We review data identifying the roles of key DPP4 substrates in transducing the glucoregulatory, anti-inflammatory, and cardiometabolic actions of DPP4 inhibitors in both preclinical and clinical studies. Finally, we highlight experimental pitfalls and technical challenges encountered in studies designed to understand the mechanisms of action and downstream targets activated by inhibition of DPP4.
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Affiliation(s)
- Erin E Mulvihill
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada
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28
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Miyoshi T, Nakamura K, Yoshida M, Miura D, Oe H, Akagi S, Sugiyama H, Akazawa K, Yonezawa T, Wada J, Ito H. Effect of vildagliptin, a dipeptidyl peptidase 4 inhibitor, on cardiac hypertrophy induced by chronic beta-adrenergic stimulation in rats. Cardiovasc Diabetol 2014; 13:43. [PMID: 24521405 PMCID: PMC3926272 DOI: 10.1186/1475-2840-13-43] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 02/06/2014] [Indexed: 01/09/2023] Open
Abstract
Background Heart failure with left ventricular (LV) hypertrophy is often associated with insulin resistance and inflammation. Recent studies have shown that dipeptidyl peptidase 4 (DPP4) inhibitors improve glucose metabolism and inflammatory status. We therefore evaluated whether vildagliptin, a DPP4 inhibitor, prevents LV hypertrophy and improves diastolic function in isoproterenol-treated rats. Methods Male Wistar rats received vehicle (n = 20), subcutaneous isoproterenol (2.4 mg/kg/day, n = 20) (ISO), subcutaneous isoproterenol (2.4 mg/kg/day + oral vildagliptin (30 mg/kg/day, n = 20) (ISO-VL), or vehicle + oral vildagliptin (30 mg/kg/day, n = 20) (vehicle-VL) for 7 days. Results Blood pressure was similar among the four groups, whereas LV hypertrophy was significantly decreased in the ISO-VL group compared with the ISO group (heart weight/body weight, vehicle: 3.2 ± 0.40, ISO: 4.43 ± 0.39, ISO-VL: 4.14 ± 0.29, vehicle-VL: 3.16 ± 0.16, p < 0.05). Cardiac catheterization revealed that vildagliptin lowered the elevated LV end-diastolic pressure observed in the ISO group, but other parameters regarding LV diastolic function such as the decreased minimum dp/dt were not ameliorated in the ISO-VL group. Histological analysis showed that vildagliptin attenuated the increased cardiomyocyte hypertrophy and perivascular fibrosis, but it did not affect angiogenesis in cardiac tissue. In the ISO-VL group, quantitative PCR showed attenuation of increased mRNA expression of tumor necrosis factor-α, interleukin-6, insulin-like growth factor-l, and restoration of decreased mRNA expression of glucose transporter type 4. Conclusions Vildagliptin may prevent LV hypertrophy caused by continuous exposure to isoproterenol in rats.
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Affiliation(s)
- Toru Miyoshi
- Department of Cardiovascular Therapeutics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
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29
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Calanna S, Christensen M, Holst JJ, Laferrère B, Gluud LL, Vilsbøll T, Knop FK. Secretion of glucose-dependent insulinotropic polypeptide in patients with type 2 diabetes: systematic review and meta-analysis of clinical studies. Diabetes Care 2013; 36:3346-52. [PMID: 24065842 PMCID: PMC3781498 DOI: 10.2337/dc13-0465] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To investigate glucose-dependent insulinotropic polypeptide (GIP) secretion in patients with type 2 diabetes and nondiabetic control subjects during oral glucose or meal tests. RESEARCH DESIGN AND METHODS Eligible trials were identified by The Cochrane Library, MEDLINE, Embase, and Web of Science. Data were retrieved and random-effects models for the primary meta-analysis, random-effects meta-regression, and subgroup and regression analyses were applied. RESULTS Random-effects meta-analysis of GIP responses in 23 trials during 28 different stimulation tests showed that patients with type 2 diabetes (n=363) exhibited no significant differences (P=not significant) in peak plasma GIP, total area under the curve (tAUC), time-corrected tAUC (tAUC×min(-1)), and time-corrected incremental area under the curve (iAUC×min(-1)) in comparison with nondiabetic control subjects (n=325) but had lower GIP responses as evaluated from iAUC (weighted mean difference, -648 pmol/L×min; 95% CI, -1,276 to -21). Fixed-effects models meta-analyses confirmed most of the results of the primary meta-analysis but showed iAUC×min(-1) to be reduced and showed tAUC and tAUC×min(-1) to be higher in diabetic patients. Random-effects meta-regression of the primary meta-analysis showed that age (peak GIP, tAUC, iAUC, and iAUC×min(-1)), BMI (tAUC, iAUC, and iAUC×min(-1)), and HbA1c (iAUC and iAUC×min(-1)) predicted some of the GIP outcomes. Post hoc subgroup analysis showed a negative influence of age and of HbA1c on GIP responses and showed a positive influence of BMI on GIP responses. CONCLUSIONS Our results suggest that patients with type 2 diabetes are characterized by preserved GIP secretion in response to oral glucose and meal tests. They also suggest that high BMI is associated with increased GIP responses but increasing age and HbA1c are associated with reduced GIP secretion.
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30
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Idorn T, Knop FK, Jørgensen M, Holst JJ, Hornum M, Feldt-Rasmussen B. Postprandial responses of incretin and pancreatic hormones in non-diabetic patients with end-stage renal disease. Nephrol Dial Transplant 2013; 29:119-27. [PMID: 24078334 DOI: 10.1093/ndt/gft353] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Patients with end-stage renal disease (ESRD) have glucometabolic disturbances resulting in a high prevalence of prediabetes. The underlying pathophysiology remains unclear, but may prove important for the strategies employed to prevent progression to overt diabetes. Meal-induced release of the insulinotropic gut-derived incretin hormones and pancreatic hormones play a critical role in the maintenance of a normal postprandial glucose tolerance. METHODS We studied patients with ESRD and either normal (n = 10) or impaired (n = 10) glucose tolerance, and control subjects (n = 11). Plasma concentrations of glucose, insulin, glucagon, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and paracetamol were measured repeatedly during a standardized 4-h liquid meal including 1.5 g paracetamol (added for evaluation of gastric emptying). RESULTS Fasting glucose and postprandial glucose responses were comparable between groups (P > 0.082). Patients with ESRD exhibited higher fasting levels of GIP and glucagon compared with controls (P < 0.001). Baseline-corrected GLP-1 and glucagon responses were enhanced (P < 0.002), baseline-corrected insulin responses and insulin excursions were reduced (P < 0.035), and paracetamol excursions were delayed (P < 0.024) in patients with ESRD compared with controls. None of the variables differed between the two ESRD subgroups. CONCLUSIONS Non-diabetic patients with ESRD were characterized by reduced postprandial insulin responses despite increased secretion of the insulinotropic incretin hormone GLP-1. Fasting levels and baseline-corrected responses of glucagon were elevated and gastric emptying was delayed in the ESRD patients. These perturbations seem to be caused by uraemia per se and may contribute to the disturbed glucose metabolism in ESRD patients.
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Affiliation(s)
- Thomas Idorn
- Department of Nephrology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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31
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Zhong J, Rao X, Rajagopalan S. An emerging role of dipeptidyl peptidase 4 (DPP4) beyond glucose control: potential implications in cardiovascular disease. Atherosclerosis 2012; 226:305-14. [PMID: 23083681 DOI: 10.1016/j.atherosclerosis.2012.09.012] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/22/2012] [Accepted: 09/14/2012] [Indexed: 02/09/2023]
Abstract
The introduction of dipeptidyl peptidase 4 (DPP4) inhibitors for the treatment of Type 2 diabetes acknowledges the fundamental importance of incretin hormones in the regulation of glycemia. Small molecule inhibitors of DPP4 exert their effects via inhibition of enzymatic degradation of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). The widespread expression of DPP4 in tissues such as the vasculature and immune cells suggests that this protein may play a role in cardiovascular function. DPP4 is known to exert its effects via both enzymatic and non-enzymatic mechanisms. A soluble form of DPP4 lacking the cytoplasmic and transmembrane domain has also been recently recognized. Besides enzymatic inactivation of incretins, DPP4 also mediates degradation of many chemokines and neuropeptides. The non-enzymatic function of DPP4 plays a critical role in providing co-stimulatory signals to T cells via adenosine deaminase (ADA). DPP4 may also regulate inflammatory responses in innate immune cells such as monocytes and dendritic cells. The multiplicity of functions and targets suggests that DPP4 may play a distinct role aside from its effects on the incretin axis. Indeed recent studies in experimental models of atherosclerosis provide evidence for a robust effect for these drugs in attenuating inflammation and plaque development. Several prospective randomized controlled clinical trials in humans with established atherosclerosis are testing the effects of DPP4 inhibition on hard cardiovascular events.
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Affiliation(s)
- Jixin Zhong
- Davis Heart and Lung Research Institute and Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH, USA
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32
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Porter D, Faivre E, Flatt PR, Hölscher C, Gault VA. Actions of incretin metabolites on locomotor activity, cognitive function and in vivo hippocampal synaptic plasticity in high fat fed mice. Peptides 2012; 35:1-8. [PMID: 22465882 DOI: 10.1016/j.peptides.2012.03.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 03/16/2012] [Accepted: 03/16/2012] [Indexed: 02/05/2023]
Abstract
The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) improve markers of cognitive function in obesity-diabetes, however, both are rapidly degraded to their major metabolites, GLP-1(9-36)amide and GIP(3-42), respectively. Therefore, the present study investigated effects of GLP-1(9-36)amide and GIP(3-42) on locomotor activity, cognitive function and hippocampal synaptic plasticity in mice with diet-induced obesity and insulin resistance. High-fat fed Swiss TO mice treated with GLP-1(9-36)amide, GIP(3-42) or exendin(9-39)amide (twice-daily for 60 days) did not exhibit any changes in bodyweight, non-fasting plasma glucose and plasma insulin concentrations or glucose tolerance compared with high-fat saline controls. Similarly, locomotor and feeding activity, O(2) consumption, CO(2) production, respiratory exchange ratio and energy expenditure were not altered by chronic treatment with incretin metabolites. Administration of the truncated metabolites did not alter general behavior in an open field test or learning and memory ability as recorded during an object recognition test. High-fat mice exhibited a significant impairment in hippocampal long-term potentiation (LTP) which was not affected by treatment with incretin metabolites. These data indicate that incretin metabolites do not influence locomotor activity, cognitive function and hippocampal synaptic plasticity when administered at pharmacological doses to mice fed a high-fat diet.
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Affiliation(s)
- David Porter
- The SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, United Kingdom
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Troutt JS, Siegel RW, Chen J, Sloan JH, Deeg MA, Cao G, Konrad RJ. Dual-Monoclonal, Sandwich Immunoassay Specific for Glucose-Dependent Insulinotropic Peptide1-42, the Active Form of the Incretin Hormone. Clin Chem 2011; 57:849-55. [DOI: 10.1373/clinchem.2010.159954] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND
Glucose-dependent insulinotropic peptide (GIP) is an incretin peptide secreted by intestinal K cells that stimulates insulin secretion in a glucose-dependent manner. It is secreted as an active, intact 42–amino acid peptide GIP1-42, which is rapidly degraded by dipeptidyl peptidase 4 to GIP3-42, which is inactive. There is currently no described monoclonal antibody–based sandwich immunoassay to quantify concentrations of GIP1-42, the active form of the peptide.
METHODS
To create a sandwich ELISA for GIP1-42, we generated a monoclonal antibody specific for the intact N-terminus of the peptide, which was further optimized to increase its affinity. We used this antibody as a conjugate antibody in a sandwich ELISA and paired it with an anti–total GIP capture monoclonal antibody to create a dual monoclonal sandwich ELISA for GIP1-42.
RESULTS
The sandwich ELISA was highly specific for GIP1-42 and did not recognize GIP3-42. The ELISA demonstrated a broad dynamic range and a lower limit of quantification of 5 ng/L. Using the ELISA, we were able to show that GIP1-42 concentrations in healthy volunteers increased dramatically in the postprandial state compared to the fasting state. GIP1-42 values were correlated with total GIP values overall; however, there was substantial interindividual variation.
CONCLUSIONS
The use of an N-terminal–specific monoclonal antibody in a sandwich ELISA format provides a robust and convenient method for measuring concentrations of GIP1-42, the active form of the incretin hormone. This ELISA should help to improve our understanding of the role of GIP1-42 in regulating glucose-dependent insulin secretion.
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Affiliation(s)
- Jason S Troutt
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Robert W Siegel
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Jinbiao Chen
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - John H Sloan
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Mark A Deeg
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Guoqing Cao
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Robert J Konrad
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
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Freyse EJ, Berg S, Kohnert KD, Heinke P, Salzsieder E. DPP-4 inhibition increases GIP and decreases GLP-1 incretin effects during intravenous glucose tolerance test in Wistar rats. Biol Chem 2011; 392:209-15. [PMID: 21281062 DOI: 10.1515/bc.2011.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
GIP metabolite [GIP (3-42)] and GLP-1 metabolite [GLP-1 (9-36) amide] have been reported to differ with regard to biological actions. Systemic DPP-4 inhibition can therefore reveal different actions of GIP and GLP-1. In catheter wearing Wistar rats, insulinotropic effects of equipotent doses of GIP (2.0 nmol/kg) and GLP-1 (7-36) amide (4.0 nmol/kg) and vehicle were tested in the absence/presence of DPP-4 inhibition. Blood glucose and insulin were frequently sampled. DPP-4 inhibitor was given at -20 min, the incretin at -5 min and the intravenous glucose tolerance test (0.4 g glucose/kg) commenced at 0 min. G-AUC and I-AUC, insulinogenic index and glucose efflux, were calculated from glucose and insulin curves. Systemic DPP-4 inhibition potentiated the acute GIP incretin effects: I-AUC (115±34 vs. 153±39 ng·min/ml), increased the insulinogenic index (0.74±0.24 vs. 0.99±0.26 ng/mmol), and improved glucose efflux (19.8±3.1 vs. 20.5±5.0 min⁻¹). The GLP-1 incretin effects were diminished: I-AUC (124±18 vs. 106±38 ng·min/ml), the insulinogenic index was decreased (0.70±0.18 vs. 0.50±0.19 ng/mmol), and glucose efflux declined (14.9±3.1 vs. 11.1±3.7 min⁻¹). GLP-1 and GIP differ remarkably in their glucoregulatory actions in healthy rats when DPP-4 is inhibited. These previously unrecognized actions of DPP-4 inhibitors could have implications for future use in humans.
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Kerr BD, Flatt AJS, Flatt PR, Gault VA. Characterization and biological actions of N-terminal truncated forms of glucose-dependent insulinotropic polypeptide. Biochem Biophys Res Commun 2010; 404:870-6. [PMID: 21184739 DOI: 10.1016/j.bbrc.2010.12.077] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 12/15/2010] [Indexed: 12/25/2022]
Abstract
The N-terminal domain of glucose-dependent insulinotropic polypeptide (GIP) plays an important role in regulating biological activity. This study examined biological properties of several N-terminal truncated forms of GIP and two novel forms with substitutions at Phe position-6 with Arg or Val. GIP(6-42), GIP(R6-42), GIP(V6-42), GIP(7-42) and GIP(9-42) stimulated cAMP production in BRIN-BD11 cells similar to native GIP, whereas responses to GIP(3-42), GIP(4-42), GIP(5-42) and GIP(8-42) were reduced (P<0.01 to P<0.001). GIP-induced cyclic AMP production was significantly inhibited by GIP(3-42), GIP(4-42), GIP(5-42), GIP(6-42), GIP(R6-42), GIP(7-42) and GIP(8-42) (P<0.001). Compared with native GIP, in vitro insulinotropic activity of GIP(3-42), GIP(4-42), GIP(5-42), GIP(7-42) and GIP(8-42) was reduced (P<0.05 to P<0.001), with GIP(4-42), GIP(5-42), GIP(7-42) and GIP(8-42) also potently inhibiting GIP-stimulated insulin secretion (P<0.001). In ob/ob mice, GIP(4-42) and GIP(8-42) increased (P<0.05 to P<0.01) plasma glucose concentrations compared to the glucose-lowering action of native GIP. When GIP(8-42) was co-administered with native GIP it countered the ability of the native peptide to lower plasma glucose and increase circulating insulin concentrations. These data confirm the importance of the N-terminal region of GIP in regulating bioactivity and reveal that sequential truncation of the peptide yields novel GIP receptor antagonists which may have functional significance.
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Affiliation(s)
- Barry D Kerr
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
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Abstract
The measurement of the incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), using immunologically based assays is made difficult by the fact that the processing of the precursor molecules gives rise to a number of different peptides which cross-react with antisera raised against the two hormones. For GLP-1, the picture is further complicated because of the necessity to differentiate between the intestinal and pancreatic proglucagon products. Finally, once secreted, both incretins are rapidly degraded by the enzyme dipeptidyl peptidase-4 (DPP-4) to generate metabolites which have lost their insulinotropic activities. These metabolites are the major circulating forms of the incretins, accounting for 60-80% of total immunoreactive GLP-1 and GIP in the peripheral plasma, while concentrations of the intact forms can be very low and, in some cases, barely detectable. The use of highly specific assays using well-characterised antisera and careful sample handling is therefore required for a reliable determination of incretin hormone concentrations.
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Affiliation(s)
- Carolyn F Deacon
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark.
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Abstract
Glucose-dependent insulinotropic polypeptide (GIP or gastric inhibitory polypeptide) is a 42-amino-acid hormone, secreted from the enteroendocrine K cells, which has insulin-releasing and extrapancreatic glucoregulatory actions. However, the unfavourable pharmacokinetic profile and the weak biological effects of native GIP limit its effectiveness for the treatment of type 2 diabetes. To overcome this, longer-acting GIP agonists exhibiting enzymatic stability and enhanced bioactivity have been generated and successfully tested in animal models of diabetes. Thus, GIP receptor agonists offer one of the newest classes of potential antidiabetic drug. GIP is also known to play a role in lipid metabolism and fat deposition. Accordingly, both genetic and chemical ablation of GIP signalling in mice with obesity-diabetes can protect against, or even reverse many of the obesity-associated metabolic disturbances. Strong parallels exist with the beneficial metabolic effects of Roux-en-Y gastric bypass in obese, insulin-resistant humans that surgically ablates GIP-secreting K cells. The purpose of this article is to highlight the therapeutic potential of GIP-based therapeutics in the treatment of type 2 diabetes and obesity.
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Affiliation(s)
- Nigel Irwin
- School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, Co. Londonderry, BT52 1SA, Northern Ireland, UK.
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Mentlein R. Mechanisms underlying the rapid degradation and elimination of the incretin hormones GLP-1 and GIP. Best Pract Res Clin Endocrinol Metab 2009; 23:443-52. [PMID: 19748062 DOI: 10.1016/j.beem.2009.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP, gastric inhibitory peptide) are secreted from intestinal L and K cells and stimulate insulin secretion from pancreatic beta cells. However, they are immediately inactivated mainly via N-terminal degradation by dipeptidyl peptidase IV (DPP IV, CD26), a specialised enzyme located on the cell surface enzyme of endothelial, epithelial and some other cell types. Cleavage by neprilysin (neutral endopeptidase) is a minor degradation route, and renal clearance eliminates incretin/fragments, but appears of less importance for regulating incretin bioactivities. Based on these observations two novel types of drugs for the treatment of type 2 diabetes have been developed: DPP IV inhibitors and DPP IV-resistant incretin analogues. Both have distinct advantages and disadvantages. Potential side effects of DPP IV inhibitors may result from affecting the bioactivity of other hormones, neuropeptides or chemokines and also by their cross-reactivity with DPP IV-related enzymes.
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Affiliation(s)
- Rolf Mentlein
- Department of Anatomy, University of Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
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Chapter 15 Glucose‐Dependent Insulinotropic Polypeptide (Gastric Inhibitory Polypeptide; GIP). VITAMINS AND HORMONES 2009; 80:409-71. [DOI: 10.1016/s0083-6729(08)00615-8] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Abstract
The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are physiological gut peptides with insulin-releasing and extrapancreatic glucoregulatory actions. Incretin analogues/mimetics activate GLP-1 or GIP receptors whilst avoiding physiological inactivation by dipeptidyl peptidase 4 (DPP-4), and they represent one of the newest classes of antidiabetic drug. The first clinically approved GLP-1 mimetic for the treatment of type-2 diabetes is exenatide (Byetta/exendin) which is administered subcutaneously twice daily. Clinical trials of liraglutide, a GLP-1 analogue suitable for once-daily administration, are ongoing. A number of other incretin molecules are at earlier stages of development. This review discusses the various attributes of GLP-1 and GIP for diabetes treatment and summarises current clinical data. Additionally, it explores the therapeutic possibilities offered by preclinical agents, such as non-peptide GLP-1 mimetics, GLP-1/glucagon hybrid peptides, and specific GIP receptor antagonists.
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Affiliation(s)
- Brian D Green
- School of Biological Sciences, Queens University Belfast, David Keir Building, Stranmillis Road, Belfast BT6 0NJ, Northern Ireland, UK.
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Gault VA, McClean PL, Irwin N, Power GJ, McCluskey JT, Flatt PR. Effects of subchronic treatment with the long-acting glucose-dependent insulinotropic polypeptide receptor agonist, N-AcGIP, on glucose homeostasis in streptozotocin-induced diabetes. Pancreas 2007; 35:73-9. [PMID: 17575548 DOI: 10.1097/mpa.0b013e31804fa19a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES N-AcGIP is a potent and dipeptidylpeptidase IV-resistant analogue of glucose-dependent insulinotropic polypeptide with significantly improved antidiabetic actions in type 2 diabetes. The present study investigated the effects of subchronic treatment with N-AcGIP on glucose homeostasis in a type 1 model, namely, streptozotocin (STZ)-induced diabetic mice. METHODS Swiss TO mice given a single intraperitoneal injection of STZ (150 mg/kg body weight) received once-daily injection of N-AcGIP (25 nmol/kg body weight) or saline for 20 days and effects on metabolic parameters and islet architecture assessed. RESULTS Daily injection of N-AcGIP for 20 days did not significantly alter the characteristic STZ-induced changes of pancreatic insulin content, body weight, food intake, glucose, and glycated hemoglobin levels. Glucose tolerance and insulin sensitivity were also unchanged by N-AcGIP treatment. Circulating insulin was undetectable, and the number of intact islets and insulin expression was greatly reduced in both groups. Some proliferative activity was identified by 5-bromo-2-deoxyuridine staining in the pancreas, but this and expression of glucagon and somatostatin were similar in the 2 groups. CONCLUSIONS These data indicate that subchronic treatment with the long-acting glucose-dependent insulinotropic polypeptide receptor agonist, N-AcGIP, does not have beneficial effects in insulin-deficient STZ-diabetic mice. This supports the primary antidiabetic action of this analogue in type 2 diabetes as stimulation of beta-cell function and insulin secretion.
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Affiliation(s)
- Victor A Gault
- Diabetes Research Group, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
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Drucker DJ. Dipeptidyl peptidase-4 inhibition and the treatment of type 2 diabetes: preclinical biology and mechanisms of action. Diabetes Care 2007; 30:1335-43. [PMID: 17337495 DOI: 10.2337/dc07-0228] [Citation(s) in RCA: 290] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Daniel J Drucker
- Department of Medicine, Banting and Best Diabetes Centre, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Ontario, Canada.
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O'Harte FPM, Hunter K, Gault VA, Irwin N, Green BD, Greer B, Harriott P, Bailey CJ, Flatt PR. Antagonistic effects of two novel GIP analogs, (Hyp3)GIP and (Hyp3)GIPLys16PAL, on the biological actions of GIP and longer-term effects in diabetic ob/ob mice. Am J Physiol Endocrinol Metab 2007; 292:E1674-82. [PMID: 17299087 DOI: 10.1152/ajpendo.00391.2006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examines the actions of the novel enzyme-resistant, NH2-terminally modified GIP analog (Hyp(3))GIP and its fatty acid-derivatized analog (Hyp(3))GIPLys(16)PAL. Acute effects are compared with the established GIP receptor antagonist (Pro(3))GIP. All three peptides exhibited DPP IV resistance, and significantly inhibited GIP stimulated cAMP formation and insulin secretion in GIP receptor-transfected fibroblasts and in clonal pancreatic BRIN-BD11 cells, respectively. Likewise, in obese diabetic ob/ob mice, intraperitoneal administration of GIP analogs significantly inhibited the acute antihyperglycemic and insulin-releasing effects of native GIP. Administration of once daily injections of (Hyp(3))GIP or (Hyp(3))GIPLys(16)PAL for 14 days resulted in significantly lower plasma glucose levels (P < 0.05) after (Hyp(3))GIP on days 12 and 14 and enhanced glucose tolerance (P < 0.05) and insulin sensitivity (P < 0.05 to P < 0.001) in both groups by day 14. Both (Hyp(3))GIP and (Hyp(3))GIPLys(16)PAL treatment also reduced pancreatic insulin (P < 0.05 to P < 0.01) without affecting islet number. These data indicate that (Hyp(3))GIP and (Hyp(3))GIPLys(16)PAL function as GIP receptor antagonists with potential for ameliorating obesity-related diabetes. Acylation of (Hyp(3))GIP to extend bioactivity does not appear to be of any additional benefit.
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Affiliation(s)
- Finbarr P M O'Harte
- School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland.
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Bibliography. Current world literature. Growth and development. Curr Opin Endocrinol Diabetes Obes 2007; 14:74-89. [PMID: 17940424 DOI: 10.1097/med.0b013e32802e6d87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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