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Cui Y, Auclair H, He R, Zhang Q. GPCR-mediated regulation of beige adipocyte formation: Implications for obesity and metabolic health. Gene 2024; 915:148421. [PMID: 38561165 DOI: 10.1016/j.gene.2024.148421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/10/2024] [Accepted: 03/29/2024] [Indexed: 04/04/2024]
Abstract
Obesity and its associated complications pose a significant burden on health. The non-shivering thermogenesis (NST) and metabolic capacity properties of brown adipose tissue (BAT), which are distinct from those of white adipose tissue (WAT), in combating obesity and its related metabolic diseases has been well documented. However, beige adipose tissue, the third and relatively novel type of adipose tissue, which emerges in extensive presence of WAT and shares similar favorable metabolic properties with BAT, has garnered considerable attention in recent years. In this review, we focused on the role of G protein-coupled receptors (GPCRs), the largest receptor family and the most successful class of drug targets in humans, in the induction of beige adipocytes. More importantly, we highlight researchers' clinical treatment attempts to ameliorate obesity and other related metabolic diseases through the formation and activation of beige adipose tissue. In summary, this review provides valuable insights into the formation of beige adipose tissue and the involvement of GPCRs, based on the latest advancements in scientific research.
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Affiliation(s)
- Yuanxu Cui
- Animal Zoology Department, Kunming Medical University, Kunming, China; Science and Technology Achievement Incubation Center, Kunming Medical University, Kunming, China
| | - Hugo Auclair
- Faculty of Medicine, François-Rabelais University, Tours, France
| | - Rong He
- Animal Zoology Department, Kunming Medical University, Kunming, China
| | - Qiang Zhang
- Animal Zoology Department, Kunming Medical University, Kunming, China.
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2
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Ali NH, Al-Kuraishy HM, Al-Gareeb AI, Hadi NR, Assiri AA, Alrouji M, Welson NN, Alexiou A, Papadakis M, Batiha GES. Hypoglycemia and Alzheimer Disease Risk: The Possible Role of Dasiglucagon. Cell Mol Neurobiol 2024; 44:55. [PMID: 38977507 PMCID: PMC11230952 DOI: 10.1007/s10571-024-01489-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 06/21/2024] [Indexed: 07/10/2024]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory impairment and cognitive dysfunctions. It has been shown that hypoglycemia can adversely affect AD neuropathology. It is well-known that chronic hyperglycemia in type 2 diabetes (T2D) is regarded as a potential risk factor for the development and progression of AD. However, the effect of recurrent hypoglycemia on the pathogenesis of AD was not deeply discussed, and how recurrent hypoglycemia affects AD at cellular and molecular levels was not intensely interpreted by the previous studies. The underlying mechanisms for hypoglycaemia-induced AD are diverse such as endothelial dysfunction, thrombosis, and neuronal injury that causing tau protein hyperphosphorylation and the accumulation of amyloid beta (Aβ) in the brain neurons. Of note, the glucagon hormone, which controls blood glucose, can also regulate the cognitive functions. Glucagon increases blood glucose by antagonizing the metabolic effect of insulin. Therefore, glucagon, through attenuation of hypoglycemia, may prevent AD neuropathology. Glucagon/GLP-1 has been shown to promote synaptogenesis, hippocampal synaptic plasticity, and learning and memory, while attenuating amyloid and tau pathologies. Therefore, activation of glucagon receptors in the brain may reduce AD neuropathology. A recent glucagon receptor agonist dasiglucagon which used in the management of hypoglycemia may be effective in preventing hypoglycemia and AD neuropathology. This review aims to discuss the potential role of dasiglucagon in treating hypoglycemia in AD, and how this drug reduce AD neuropathology.
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Affiliation(s)
- Naif H Ali
- Assistant Professor of Neurology, Department of Internal Medicine, Medical College, Najran University, Najran, Kingdom of Saudi Arabia
| | - Hayder M Al-Kuraishy
- Department of Clinical Pharmacology and Medicine, College of Medicine, Mustansiriyah University, Baghdad, Iraq
| | - Ali I Al-Gareeb
- Head of Jabir Ibn, Hayyan Medical University, Al-Ameer Qu./Najaf-Iraq, PO.Box13, Kufa, Iraq
| | - Najah R Hadi
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Kufa, Kufa, Iraq
| | - Abdullah A Assiri
- Department of Clinical Pharmacy, College of Pharmacy, King Khalid University, Abha, Kingdom of Saudi Arabia
| | - Mohammed Alrouji
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Shaqra University, Shaqra, 11961, Kingdom of Saudi Arabia
| | - Nermeen N Welson
- Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Beni-Suef University, Beni Suef, 62511, Egypt
| | - Athanasios Alexiou
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham, NSW, 2770, Australia
- AFNP Med, 1030, Vienna, Austria
- University Centre for Research & Development, Chandigarh University, Punjab, India
- Department of Research & Development, Funogen, Athens, Greece
| | - Marios Papadakis
- Department of Surgery II, University Hospital Witten-Herdecke, Heusnerstrasse 40, University of Witten-Herdecke, 42283, Wuppertal, Germany
| | - Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, AlBeheira, 22511, Egypt
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3
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Horie I, Abiru N. Advances in clinical research on glucagon. Diabetol Int 2024; 15:353-361. [PMID: 39101175 PMCID: PMC11291794 DOI: 10.1007/s13340-024-00705-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 02/19/2024] [Indexed: 08/06/2024]
Abstract
We are now celebrating the 100th anniversary of the discovery of an important pancreatic hormone, glucagon. Glucagon is historically described as a diabetogenic hormone elevating glucose levels via increases in insulin resistance and hepatic gluconeogenesis. The more recently identified actions of glucagon include not only its pathophysiologic effects on glucose metabolism but also its significant roles in amino-acid metabolism in the liver. The possibility that abnormalities in α-cells' secretion of glucagon in metabolic disorders are a compensatory adaptation for the maintenance of metabolic homeostasis is another current issue. However, the clinical research concerning glucagon has been considerably behind the advances in basic research due to the lack of suitable methodology for obtaining precise measurements of plasma glucagon levels in humans. The precise physiology of glucagon secretory dynamics in individuals with metabolic dysfunction (including diabetes) has been clarified since the development in 2014 of a quantitative measurement technique for glucagon. In this review, we summarize the advances in the clinical research concerning glucagon, including those of our studies and the relevant literature.
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Affiliation(s)
- Ichiro Horie
- Department of Endocrinology and Metabolism, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, 852-8501 Japan
| | - Norio Abiru
- Department of Endocrinology and Metabolism, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, 852-8501 Japan
- Medical Health Examination Center, Midori Clinic, 32-20 Joei-Machi, Nagasaki, 852-8034 Japan
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4
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Yin X, Ni G, Zhang X, Fu S, Li H, Gao Z. Tyrosine nitration of glucagon impairs its function: Extending the role of heme in T2D pathogenesis. J Inorg Biochem 2024; 255:112519. [PMID: 38507994 DOI: 10.1016/j.jinorgbio.2024.112519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 02/24/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024]
Abstract
New studies raise the possibility that the higher glucagon (GCG) level present in type 2 diabetes (T2D) is a compensatory mechanism to enhance β-cell function, rather than induce dysregulated glucose homeostasis, due to an important role for GCG that acts directly within the pancreas on insulin secretion by intra-islet GCG signaling. However, in states of poorly controlled T2D, pancreatic α cell mass increases (overproduced GCG) in response to insufficient insulin secretion, indicating decreased local GCG activity. The reason for this decrease is not clear. Recent evidence has uncovered a new role of heme in cellular signal transduction, and its mechanism involves reversible binding of heme to proteins. Considering that protein tyrosine nitration in diabetic islets increases and glucose-stimulated insulin secretion (GSIS) decreases, we speculated that heme modulates GSIS by transient interaction with GCG and catalyzing its tyrosine nitration, and the tyrosine nitration may impair GCG activity, leading to loss of intra-islet GCG signaling and markedly impaired insulin secretion. Data presented here elucidate a novel role for heme in disrupting local GCG signaling in diabetes. Heme bound to GCG and induced GCG tyrosine nitration. Two tyrosine residues in GCG were both sensitive to the nitrating species. Further, GCG was also demonstrated to be a preferred target peptide for tyrosine nitration by co-incubation with BSA. Tyrosine nitration impaired GCG stimulated cAMP-dependent signaling in islet β cells and decreased insulin release. Our results provided a new role of heme for impaired GSIS in the pathological process of diabetes.
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Affiliation(s)
- Xiaoying Yin
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China
| | - Guoqi Ni
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China
| | - Xuan Zhang
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China
| | - Shitao Fu
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China
| | - Hailing Li
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China.
| | - Zhonghong Gao
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, Wuhan 430074, PR China; School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China.
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5
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Ashraf A, Hassan MI. Microbial Endocrinology: Host metabolism and appetite hormones interaction with gut microbiome. Mol Cell Endocrinol 2024; 592:112281. [PMID: 38810719 DOI: 10.1016/j.mce.2024.112281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/07/2024] [Accepted: 05/26/2024] [Indexed: 05/31/2024]
Affiliation(s)
- Anam Ashraf
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
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6
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Salehi M. Alpha-Cell Secretion Across the Spectrum of Glucose Tolerance. J Clin Endocrinol Metab 2024; 109:e1456-e1457. [PMID: 37997465 DOI: 10.1210/clinem/dgad686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 11/25/2023]
Affiliation(s)
- Marzieh Salehi
- Division of Diabetes, University of Texas at San Antonio, San Antonio, TX 78229, USA
- South Texas Veteran Health Care System, Audie Murphy Hospital, San Antonio, TX 78229, USA
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7
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Kistkins S, Moser O, Ankudovičs V, Blizņuks D, Mihailovs T, Lobanovs S, Sourij H, Pfeiffer AFH, Pīrāgs V. From classical dualistic antagonism to hormone synergy: potential of overlapping action of glucagon, insulin and GLP-1 for the treatment of diabesity. Endocr Connect 2024; 13:e230529. [PMID: 38579770 PMCID: PMC11046332 DOI: 10.1530/ec-23-0529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 04/03/2024] [Indexed: 04/07/2024]
Abstract
The increasing prevalence of 'diabesity', a combination of type 2 diabetes and obesity, poses a significant global health challenge. Unhealthy lifestyle factors, including poor diet, sedentary behaviour, and high stress levels, combined with genetic and epigenetic factors, contribute to the diabesity epidemic. Diabesity leads to various significant complications such as cardiovascular diseases, stroke, and certain cancers. Incretin-based therapies, such as GLP-1 receptor agonists and dual hormone therapies, have shown promising results in improving glycaemic control and inducing weight loss. However, these therapies also come with certain disadvantages, including potential withdrawal effects. This review aims to provide insights into the cross-interactions of insulin, glucagon, and GLP-1, revealing the complex hormonal dynamics during fasting and postprandial states, impacting glucose homeostasis, energy expenditure, and other metabolic functions. Understanding these hormonal interactions may offer novel hypotheses in the development of 'anti-diabesity' treatment strategies. The article also explores the question of the antagonism of insulin and glucagon, providing insights into the potential synergy and hormonal overlaps between these hormones.
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Affiliation(s)
| | - Othmar Moser
- Division of Exercise Physiology and Metabolism, Institute of Sport Science, University of Bayreuth, Bayreuth, Germany
| | | | - Dmitrijs Blizņuks
- Institute of Smart Computing Technologies, Riga Technical University, Riga, Latvia
| | - Timurs Mihailovs
- Institute of Smart Computing Technologies, Riga Technical University, Riga, Latvia
| | | | - Harald Sourij
- Trials Unit for Interdisciplinary Metabolic Medicine, Division of Endocrinology and Diabetolgoy, Medical University of Graz, Graz, Austria
| | - Andreas F H Pfeiffer
- Department of Endocrinology and Metabolic Medicine, Campus Benjamin Franklin, Charité University Medicine, Hindenburgdamm, Berlin, Germany
| | - Valdis Pīrāgs
- Pauls Stradiņš Clinical University Hospital, Riga, Latvia
- Faculty of Medicine, University of Latvia, Riga, Latvia
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8
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Gray SM, Goonatilleke E, Emrick MA, Becker JO, Hoofnagle AN, Stefanovski D, He W, Zhang G, Tong J, Campbell J, D’Alessio DA. High Doses of Exogenous Glucagon Stimulate Insulin Secretion and Reduce Insulin Clearance in Healthy Humans. Diabetes 2024; 73:412-425. [PMID: 38015721 PMCID: PMC10882148 DOI: 10.2337/db23-0201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 11/20/2023] [Indexed: 11/30/2023]
Abstract
Glucagon is generally defined as a counterregulatory hormone with a primary role to raise blood glucose concentrations by increasing endogenous glucose production (EGP) in response to hypoglycemia. However, glucagon has long been known to stimulate insulin release, and recent preclinical findings have supported a paracrine action of glucagon directly on islet β-cells that augments their secretion. In mice, the insulinotropic effect of glucagon is glucose dependent and not present during basal euglycemia. To test the hypothesis that the relative effects of glucagon on hepatic and islet function also vary with blood glucose, a group of healthy subjects received glucagon (100 ng/kg) during fasting glycemia or experimental hyperglycemia (∼150 mg/dL) on 2 separate days. During fasting euglycemia, administration of glucagon caused blood glucose to rise due to increased EGP, with a delayed increase of insulin secretion. When given during experimental hyperglycemia, glucagon caused a rapid, threefold increase in insulin secretion, as well as a more gradual increase in EGP. Under both conditions, insulin clearance was decreased in response to glucagon infusion. The insulinotropic action of glucagon, which is proportional to the degree of blood glucose elevation, suggests distinct physiologic roles in the fasting and prandial states. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Sarah M. Gray
- Duke Molecular Physiology Institute, Duke University, Durham, NC
| | - Elisha Goonatilleke
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA
| | - Michelle A. Emrick
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA
| | - Jessica O. Becker
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA
| | - Andrew N. Hoofnagle
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA
| | - Darko Stefanovski
- Department of Clinical Studies–New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square
| | - Wentao He
- Duke Molecular Physiology Institute, Duke University, Durham, NC
| | - Guofang Zhang
- Duke Molecular Physiology Institute, Duke University, Durham, NC
| | - Jenny Tong
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA
- Endocrine Section, VA Puget Sound Health Care System, Seattle
| | - Jonathan Campbell
- Duke Molecular Physiology Institute, Duke University, Durham, NC
- Division of Endocrinology, Department of Medicine, Duke University, Durham, NC
| | - David A. D’Alessio
- Duke Molecular Physiology Institute, Duke University, Durham, NC
- Division of Endocrinology, Department of Medicine, Duke University, Durham, NC
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9
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Allard C, Cota D, Quarta C. Poly-Agonist Pharmacotherapies for Metabolic Diseases: Hopes and New Challenges. Drugs 2024; 84:127-148. [PMID: 38127286 DOI: 10.1007/s40265-023-01982-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2023] [Indexed: 12/23/2023]
Abstract
The use of glucagon-like peptide-1 (GLP-1) receptor-based multi-agonists in the treatment of type 2 diabetes and obesity holds great promise for improving glycaemic control and weight management. Unimolecular dual and triple agonists targeting multiple gut hormone-related pathways are currently in clinical trials, with recent evidence supporting their efficacy. However, significant knowledge gaps remain regarding the biological mechanisms and potential adverse effects associated with these multi-target agents. The mechanisms underlying the therapeutic efficacy of GLP-1 receptor-based multi-agonists remain somewhat mysterious, and hidden threats may be associated with the use of gut hormone-based polyagonists. In this review, we provide a critical analysis of the benefits and risks associated with the use of these new drugs in the management of obesity and diabetes, while also exploring new potential applications of GLP-1-based pharmacology beyond the field of metabolic disease.
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Affiliation(s)
- Camille Allard
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, 33000, Bordeaux, France
| | - Daniela Cota
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, 33000, Bordeaux, France
| | - Carmelo Quarta
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, 33000, Bordeaux, France.
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Welch AA, Farahani RA, Egan AM, Laurenti MC, Zeini M, Vella M, Bailey KR, Cobelli C, Dalla Man C, Matveyenko A, Vella A. Glucagon-like peptide-1 receptor blockade impairs islet secretion and glucose metabolism in humans. J Clin Invest 2023; 133:e173495. [PMID: 37751301 PMCID: PMC10645389 DOI: 10.1172/jci173495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 09/12/2023] [Indexed: 09/27/2023] Open
Abstract
BACKGROUNDProglucagon can be processed to glucagon-like peptide1 (GLP-1) within the islet, but its contribution to islet function in humans remains unknown. We sought to understand whether pancreatic GLP-1 alters islet function in humans and whether this is affected by type 2 diabetes.METHODSWe therefore studied individuals with and without type 2 diabetes on two occasions in random order. On one occasion, exendin 9-39, a competitive antagonist of the GLP-1 Receptor (GLP1R), was infused, while on the other, saline was infused. The tracer dilution technique ([3-3H] glucose) was used to measure glucose turnover during fasting and during a hyperglycemic clamp.RESULTSExendin 9-39 increased fasting glucose concentrations; fasting islet hormone concentrations were unchanged, but inappropriate for the higher fasting glucose observed. In people with type 2 diabetes, fasting glucagon concentrations were markedly elevated and persisted despite hyperglycemia. This impaired suppression of endogenous glucose production by hyperglycemia.CONCLUSIONThese data show that GLP1R blockade impairs islet function, implying that intra-islet GLP1R activation alters islet responses to glucose and does so to a greater degree in people with type 2 diabetes.TRIAL REGISTRATIONThis study was registered at ClinicalTrials.gov NCT04466618.FUNDINGThe study was primarily funded by NIH NIDDK DK126206. AV is supported by DK78646, DK116231 and DK126206. CDM was supported by MIUR (Italian Minister for Education) under the initiative "Departments of Excellence" (Law 232/2016).
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Affiliation(s)
- Andrew A. Welch
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Rahele A. Farahani
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Aoife M. Egan
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Marcello C. Laurenti
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Maya Zeini
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Max Vella
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Kent R. Bailey
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Aleksey Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Adrian Vella
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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Folli F, Finzi G, Manfrini R, Galli A, Casiraghi F, Centofanti L, Berra C, Fiorina P, Davalli A, La Rosa S, Perego C, Higgins PB. Mechanisms of action of incretin receptor based dual- and tri-agonists in pancreatic islets. Am J Physiol Endocrinol Metab 2023; 325:E595-E609. [PMID: 37729025 PMCID: PMC10874655 DOI: 10.1152/ajpendo.00236.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/15/2023] [Accepted: 09/16/2023] [Indexed: 09/22/2023]
Abstract
Simultaneous activation of the incretin G-protein-coupled receptors (GPCRs) via unimolecular dual-receptor agonists (UDRA) has emerged as a new therapeutic approach for type 2 diabetes. Recent studies also advocate triple agonism with molecules also capable of binding the glucagon receptor. In this scoping review, we discuss the cellular mechanisms of action (MOA) underlying the actions of these novel and therapeutically important classes of peptide receptor agonists. Clinical efficacy studies of several UDRAs have demonstrated favorable results both as monotherapies and when combined with approved hypoglycemics. Although the additive insulinotropic effects of dual glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic peptide receptor (GIPR) agonism were anticipated based on the known actions of either glucagon-like peptide-1 (GLP-1) or glucose-dependent insulinotropic peptide (GIP) alone, the additional benefits from GCGR were largely unexpected. Whether additional synergistic or antagonistic interactions among these G-protein receptor signaling pathways arise from simultaneous stimulation is not known. The signaling pathways affected by dual- and tri-agonism require more trenchant investigation before a comprehensive understanding of the cellular MOA. This knowledge will be essential for understanding the chronic efficacy and safety of these treatments.
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Affiliation(s)
- Franco Folli
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
- Unit of Diabetes, Endocrinology and Metabolism, San Paolo Hospital, ASST Santi Paolo e Carlo, Milan, Italy
| | - Giovanna Finzi
- Unit of Pathology, Department of Oncology, ASST Sette Laghi, Varese, Italy
| | - Roberto Manfrini
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
- Unit of Diabetes, Endocrinology and Metabolism, San Paolo Hospital, ASST Santi Paolo e Carlo, Milan, Italy
| | - Alessandra Galli
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Francesca Casiraghi
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
| | - Lucia Centofanti
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
| | - Cesare Berra
- IRCCS MultiMedica, Sesto San Giovanni, Milan, Italy
| | - Paolo Fiorina
- International Center for T1D, Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, DIBIC, Università di Milano, Milan, Italy
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States
- Division of Endocrinology, ASST Fatebenefratelli-Sacco, Milan, Italy
| | - Alberto Davalli
- Diabetes and Endocrinology Unit, Department of Internal Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Stefano La Rosa
- Unit of Pathology, Department of Medicine and Technological Innovation, University of Insubria, Varese, Italy
| | - Carla Perego
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Paul B Higgins
- Department of Life & Physical Sciences, Atlantic Technological University, Letterkenny, Ireland
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12
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Lyons SA, Beaudry JL. Synergistic Combinations of Gut- and Pancreas-Hormone-Based Therapies: Advancements in Treatments for Metabolic Diseases. Endocrinology 2023; 164:bqad153. [PMID: 37823483 PMCID: PMC10612476 DOI: 10.1210/endocr/bqad153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/29/2023] [Accepted: 10/10/2023] [Indexed: 10/13/2023]
Abstract
Metabolic diseases, such as obesity, type 2 diabetes mellitus (T2DM), cardiovascular disease, and liver disease, have become increasingly prevalent around the world. As an alternative to bariatric surgery, glucagon-like peptide 1 (GLP-1) receptor agonists have been at the forefront of weight loss medication to combat these metabolic complications. Recently, there has been an exciting rapid emergence of new weight loss medications that combine GLP-1 receptor (GLP-1R) agonists with other gut- and pancreatic-derived hormones, such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon (GCG) receptor agonists. Dual-agonist (GLP-1/GIP and GLP-1/GCG) and tri-agonist (GLP-1/GIP/GCG) administration generally result in greater weight loss, reduction of blood sugar and lipid levels, restoration of tissue function, and improvement in whole-body substrate metabolism compared to when GLP-1R agonists are used alone. The aim of this review is to summarize the recent literature of both preclinical and clinical studies on how these emerging gut-peptide therapies further improve weight loss and metabolic health outcomes for various metabolic diseases.
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Affiliation(s)
- Sulayman Aslan Lyons
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Jacqueline Leah Beaudry
- Temerty Faculty of Medicine, Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada M5S 1A8
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Zhang J, Zheng Y, Martens L, Pfeiffer AFH. The Regulation and Secretion of Glucagon in Response to Nutrient Composition: Unraveling Their Intricate Mechanisms. Nutrients 2023; 15:3913. [PMID: 37764697 PMCID: PMC10536047 DOI: 10.3390/nu15183913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Glucagon was initially regarded as a hyperglycemic substance; however, recent research has revealed its broader role in metabolism, encompassing effects on glucose, amino acids (AAs), and lipid metabolism. Notably, the interplay of glucagon with nutrient intake, particularly of AAs, and non-nutrient components is central to its secretion. Fasting and postprandial hyperglucagonemia have long been linked to the development and progression of type 2 diabetes (T2DM). However, recent studies have brought to light the positive impact of glucagon agonists on lipid metabolism and energy homeostasis. This review explores the multifaceted actions of glucagon, focusing on its regulation, signaling pathways, and effects on glucose, AAs, and lipid metabolism. The interplay between glucagon and other hormones, including insulin and incretins, is examined to provide a mechanistic understanding of its functions. Notably, the liver-α-cell axis, which involves glucagon and amino acids, emerges as a critical aspect of metabolic regulation. The dysregulation of glucagon secretion and its impact on conditions such as T2DM are discussed. The review highlights the potential therapeutic applications of targeting the glucagon pathway in the treatment of metabolic disorders.
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Affiliation(s)
- Jiudan Zhang
- The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310053, China;
- Department of Endocrinology, Diabetes and Nutrition, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (L.M.); (A.F.H.P.)
| | - Yang Zheng
- The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310053, China;
| | - Lisa Martens
- Department of Endocrinology, Diabetes and Nutrition, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (L.M.); (A.F.H.P.)
- Nutritional Science, University of Potsdam, 14469 Potsdam, Germany
| | - Andreas F. H. Pfeiffer
- Department of Endocrinology, Diabetes and Nutrition, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (L.M.); (A.F.H.P.)
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14
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Lubaczeuski C, Bozadjieva-Kramer N, Louzada RA, Gittes GK, Leibowitz G, Bernal-Mizrachi E. Time-dependent effects of endogenous hyperglucagonemia on glucose homeostasis and hepatic glucagon action. JCI Insight 2023; 8:e162255. [PMID: 37140984 PMCID: PMC10393226 DOI: 10.1172/jci.insight.162255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 05/03/2023] [Indexed: 05/05/2023] Open
Abstract
Elevation of glucagon levels and increase in α cell proliferation is associated with states of hyperglycemia in diabetes. A better understanding of the molecular mechanisms governing glucagon secretion could have major implications for understanding abnormal responses to hypoglycemia in patients with diabetes and provide novel avenues for diabetes management. Using mice with inducible induction of Rheb1 in α cells (αRhebTg mice), we showed that short-term activation of mTORC1 signaling is sufficient to induce hyperglucagonemia through increased glucagon secretion. Hyperglucagonemia in αRhebTg mice was also associated with an increase in α cell size and mass expansion. This model allowed us to identify the effects of chronic and short-term hyperglucagonemia on glucose homeostasis by regulating glucagon signaling in the liver. Short-term hyperglucagonemia impaired glucose tolerance, which was reversible over time. Liver glucagon resistance in αRhebTg mice was associated with reduced expression of the glucagon receptor and genes involved in gluconeogenesis, amino acid metabolism, and urea production. However, only genes regulating gluconeogenesis returned to baseline upon improvement of glycemia. Overall, these studies demonstrate that hyperglucagonemia exerts a biphasic response on glucose metabolism: Short-term hyperglucagonemia lead to glucose intolerance, whereas chronic exposure to glucagon reduced hepatic glucagon action and improved glucose tolerance.
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Affiliation(s)
- Camila Lubaczeuski
- Department of Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Nadejda Bozadjieva-Kramer
- Veterans Affairs Ann Arbor Healthcare System, Research Service, Ann Arbor, Michigan, USA
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Ruy A. Louzada
- Department of Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - George K. Gittes
- Childrens Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Gil Leibowitz
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ernesto Bernal-Mizrachi
- Department of Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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15
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Kaur S, Sokrat B, Capozzi ME, El K, Bai Y, Jazic A, Han B, Krishnakumar K, D'Alessio DA, Campbell JE, Bouvier M, Shenoy SK. The Ubiquitination Status of the Glucagon Receptor determines Signal Bias. J Biol Chem 2023; 299:104690. [PMID: 37037304 DOI: 10.1016/j.jbc.2023.104690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/03/2023] [Accepted: 03/31/2023] [Indexed: 04/12/2023] Open
Abstract
The pancreatic hormone glucagon activates the glucagon receptor (GCGR), a class B seven-transmembrane G protein-coupled receptor (GPCR) that couples to the stimulatory heterotrimeric Gs protein and provokes protein kinase A-dependent signaling cascades vital to hepatic glucose metabolism and islet insulin secretion. Glucagon-stimulation also initiates recruitment of the endocytic adaptors, β-arrestin1 and β-arrestin2, which regulate desensitization and internalization of the GCGR. Unlike many other GPCRs, the GCGR expressed at the plasma membrane is constitutively ubiquitinated and upon agonist-activation, internalized GCGRs are deubiquitinated at early endosomes and recycled via Rab4-containing vesicles. Herein we report a novel link between the ubiquitination status and signal transduction mechanism of the GCGR. In the deubiquitinated state, coupling of the GCGR to Gs is diminished, while binding to β-arrestin is enhanced with signaling biased to a β-arrestin1-dependent p38 mitogen activated protein kinase (MAPK) pathway. This ubiquitin-dependent signaling bias arises through the modification of lysine333 (K333) on the cytoplasmic face of transmembrane helix V. Compared with the GCGR-WT, the mutant GCGR-K333R has impaired ubiquitination, diminished G protein coupling and protein kinase A signaling, but unimpaired potentiation of glucose-stimulated-insulin secretion in response to agonist-stimulation, which involves p38 MAPK signaling. Both WT and GCGR-K333R promote the formation of glucagon-induced β-arrestin1-dependent p38 signaling scaffold that requires canonical upstream MAPK-Kinase3, but is independent of Gs, Gi and β-arrestin2. Thus ubiquitination/deubiquitination at K333 in the GCGR defines the activation of distinct transducers with the potential to influence various facets of glucagon signaling in health and disease.
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Affiliation(s)
- Suneet Kaur
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Badr Sokrat
- Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, H3T 1J4 Canada; Institute for Research in Immunology and Cancer, University of Montreal, Montreal, Quebec, H3T 1J4 Canada
| | - Megan E Capozzi
- Division of Endocrinology, Department of Medicine, Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
| | - Kimberley El
- Division of Endocrinology, Department of Medicine, Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
| | - Yushi Bai
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Aeva Jazic
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Bridgette Han
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Kaavya Krishnakumar
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford CA 94305
| | - David A D'Alessio
- Division of Endocrinology, Department of Medicine, Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
| | - Jonathan E Campbell
- Division of Endocrinology, Department of Medicine, Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
| | - Michel Bouvier
- Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, H3T 1J4 Canada; Institute for Research in Immunology and Cancer, University of Montreal, Montreal, Quebec, H3T 1J4 Canada
| | - Sudha K Shenoy
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
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16
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Zhang J, Schäfer SM, Kabisch S, Csanalosi M, Schuppelius B, Kemper M, Markova M, Meyer NMT, Pivovarova-Ramich O, Keyhani-Nejad F, Rohn S, Pfeiffer AFH. Implication of sugar, protein and incretins in excessive glucagon secretion in type 2 diabetes after mixed meals. Clin Nutr 2023; 42:467-476. [PMID: 36857956 DOI: 10.1016/j.clnu.2023.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 01/10/2023] [Accepted: 02/14/2023] [Indexed: 02/25/2023]
Abstract
AIMS Amino acids powerfully release glucagon but their contribution to postprandial hyperglucagonemia in type 2 diabetes remains unclear. Exogenously applied GIP stimulates, while GLP-1 inhibits, glucagon secretion in humans. However, their role in mixed meals is unclear, which we therefore characterized. METHODS In three experiments, participants with type 2 diabetes and obese controls randomly received different loads of sugars and/or proteins. In the first experiment, participants ingested the rapidly cleaved saccharose (SAC) or slowly cleaved isomaltulose (ISO) which is known to elicit opposite profiles of GIP and GLP-1 secretion. In the second one participants received test meals which contained saccharose or isomaltulose in combination with milk protein. The third set of participants underwent randomized oral protein tests with whey protein or casein. Incretins, glucagon, C-peptide, and insulin were profiled by specific immunological assays. RESULTS 50 g of the sugars alone suppressed glucagon in controls but slightly less in type 2 diabetes patients. Participants with type 2 diabetes showed excessive glucagon responses within 15 min and lasting over 3 h, while the obese controls showed small initial and delayed greater glucagon responses to mixed meals. The release of GIP was significantly faster and greater with SAC compared to ISO, while GLP-1 showed an inverse pattern. The glucagon responses to whey or casein were only moderately increased in type 2 diabetes patients without a left shift of the dose response curve. CONCLUSIONS The rapid hypersecretion of glucagon after mixed meals in type 2 diabetes patients compared to controls is unaffected by endogenous incretins. The defective suppression of glucagon by glucose combined with hypersecretion to protein is required for the exaggerated response. CLINICAL TRIALS NUMBERS NCT03806920, NCT02219295, NCT04564391.
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Affiliation(s)
- Jiudan Zhang
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Sylva Mareike Schäfer
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany; Institute of Nutritional Science, Justus-Liebig University of Giessen, Giessen, Germany
| | - Stefan Kabisch
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany; Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany; German Center for Diabetes Research (Deutsches Zentrum Für Diabetesforschung e.V.), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Marta Csanalosi
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Bettina Schuppelius
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Margrit Kemper
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany
| | - Mariya Markova
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany; German Center for Diabetes Research (Deutsches Zentrum Für Diabetesforschung e.V.), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Nina Marie Tosca Meyer
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany; Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany; German Center for Diabetes Research (Deutsches Zentrum Für Diabetesforschung e.V.), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Olga Pivovarova-Ramich
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany; Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany; German Center for Diabetes Research (Deutsches Zentrum Für Diabetesforschung e.V.), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany; Reseach Group Molecular Nutritional Medicine, Dept. of Molecular Toxicology, German Institute of Human Nutrition Potsdam-Rehbrücke, 14558, Nuthetal, Germany
| | - Farnaz Keyhani-Nejad
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany
| | - Sascha Rohn
- Institute of Food Chemistry, Hamburg School of Food Science, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany; Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355, Berlin, Germany
| | - Andreas F H Pfeiffer
- Department of Endocrinology, Diabetes and Nutrition, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany; German Center for Diabetes Research (Deutsches Zentrum Für Diabetesforschung e.V.), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
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17
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Lambré C, Barat Baviera JM, Bolognesi C, Chesson A, Cocconcelli PS, Crebelli R, Gott DM, Grob K, Lampi E, Mengelers M, Mortensen A, Rivière G, Silano (until 21 December 2020†) V, Steffensen I, Tlustos C, Vernis L, Zorn H, Batke M, Bignami M, Corsini E, FitzGerald R, Gundert‐Remy U, Halldorsson T, Hart A, Ntzani E, Scanziani E, Schroeder H, Ulbrich B, Waalkens‐Berendsen D, Woelfle D, Al Harraq Z, Baert K, Carfì M, Castoldi AF, Croera C, Van Loveren H. Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs. EFSA J 2023; 21:e06857. [PMID: 37089179 PMCID: PMC10113887 DOI: 10.2903/j.efsa.2023.6857] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.
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18
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Farahani RA, Egan AM, Welch AA, Laurenti MC, Cobelli C, Dalla Man C, Vella A. The Effect of Glucagon-Like Peptide 1 Receptor Blockade on Glucagon-Induced Stimulation of Insulin Secretion. Diabetes 2023; 72:449-454. [PMID: 36562995 PMCID: PMC10260388 DOI: 10.2337/db22-0709] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022]
Abstract
Data from transgenic rodent models suggest that glucagon acts as an insulin secretagogue by signaling through the glucagon-like peptide 1 receptor (GLP-1R) present on β-cells. However, its net contribution to physiologic insulin secretion in humans is unknown. To address this question, we studied individuals without diabetes in two separate experiments. Each subject was studied on two occasions in random order. In the first experiment, during a hyperglycemic clamp, glucagon was infused at 0.4 ng/kg/min, increasing by 0.2 ng/kg/min every hour for 5 h. On one day, exendin-9,39 (300 pmol/kg/min) was infused to block GLP-1R, while on the other, saline was infused. The insulin secretion rate (ISR) was calculated by nonparametric deconvolution from plasma concentrations of C-peptide. Endogenous glucose production and glucose disappearance were measured using the tracer-dilution technique. Glucagon concentrations, by design, did not differ between study days. Integrated ISR was lower during exendin-9,39 infusion (213 ± 26 vs. 191 ± 22 nmol/5 h, saline vs. exendin-9,39, respectively; P = 0.02). In the separate experiment, exendin-9,39 infusion, compared with saline infusion, also decreased the β-cell secretory response to a 1-mg glucagon bolus. These data show that, in humans without diabetes, glucagon partially stimulates the β-cell through GLP-1R.
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Affiliation(s)
- Rahele A. Farahani
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, MN
| | - Aoife M. Egan
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, MN
| | - Andrew A. Welch
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, MN
| | - Marcello C. Laurenti
- Biomedical Engineering and Physiology Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN
| | - Claudio Cobelli
- Department of Women’s and Children’s Health, University of Padova, Padova, Italy
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Adrian Vella
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, MN
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19
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Novikoff A, Müller TD. The Molecular Pharmacology of Glucagon Agonists in Diabetes and Obesity. Peptides 2023; 165:171003. [PMID: 36997003 DOI: 10.1016/j.peptides.2023.171003] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 03/31/2023]
Abstract
Within the past couple decades glucagon receptor agonism has drawn attention as a therapeutic tool for the treatment of type 2 diabetes and obesity. In both mice and humans glucagon-induced enhancements in energy expenditure and suppression of food intake suggest promising utility, therefore interest has advanced in the synthetic optimization of glucagon-based pharmacology to further resolve the physiological and cellular underpinnings. Modifications within the glucagon peptide sequence have allowed for greater solubility, stability, circulating half-life, and understanding of the structure-function potential behind partial and "super"-agonists. This knowledge gained from such modifications has provided a basis for the development of long-acting therapeutically useful glucagon analogues, chimeric unimolecular dual- and tri-agonists, and novel strategies for the targeting of nuclear hormones into glucagon receptor-expressing tissues. In this review, we summarize the peptide path leading to these glucagon-based developments in the field of anti-diabetes and anti-obesity pharmacology, while highlighting the associated biological and therapeutic effects.
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Affiliation(s)
- Aaron Novikoff
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany.
| | - Timo D Müller
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany.
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20
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Hædersdal S, Andersen A, Knop FK, Vilsbøll T. Revisiting the role of glucagon in health, diabetes mellitus and other metabolic diseases. Nat Rev Endocrinol 2023; 19:321-335. [PMID: 36932176 DOI: 10.1038/s41574-023-00817-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/17/2023] [Indexed: 03/19/2023]
Abstract
Insulin and glucagon exert opposing effects on glucose metabolism and, consequently, pancreatic islet β-cells and α-cells are considered functional antagonists. The intra-islet hypothesis has previously dominated the understanding of glucagon secretion, stating that insulin acts to inhibit the release of glucagon. By contrast, glucagon is a potent stimulator of insulin secretion and has been used to test β-cell function. Over the past decade, α-cells have received increasing attention due to their ability to stimulate insulin secretion from neighbouring β-cells, and α-cell-β-cell crosstalk has proven central for glucose homeostasis in vivo. Glucagon is not only the counter-regulatory hormone to insulin in glucose metabolism but also glucagon secretion is more susceptible to changes in the plasma concentration of certain amino acids than to changes in plasma concentrations of glucose. Thus, the actions of glucagon also include a central role in amino acid turnover and hepatic fat oxidation. This Review provides insights into glucagon secretion, with a focus on the local paracrine actions on glucagon and the importance of α-cell-β-cell crosstalk. We focus on dysregulated glucagon secretion in obesity, non-alcoholic fatty liver disease and type 2 diabetes mellitus. Lastly, the future potential of targeting hyperglucagonaemia and applying dual and triple receptor agonists with glucagon receptor-activating properties in combination with incretin hormone receptor agonism is discussed.
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Affiliation(s)
- Sofie Hædersdal
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark.
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark.
| | - Andreas Andersen
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Filip K Knop
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Tina Vilsbøll
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark.
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark.
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
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21
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Kim H, Westerman KE, Smith K, Chiou J, Cole JB, Majarian T, von Grotthuss M, Kwak SH, Kim J, Mercader JM, Florez JC, Gaulton K, Manning AK, Udler MS. High-throughput genetic clustering of type 2 diabetes loci reveals heterogeneous mechanistic pathways of metabolic disease. Diabetologia 2023; 66:495-507. [PMID: 36538063 PMCID: PMC10108373 DOI: 10.1007/s00125-022-05848-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/28/2022] [Indexed: 12/24/2022]
Abstract
AIMS/HYPOTHESIS Type 2 diabetes is highly polygenic and influenced by multiple biological pathways. Rapid expansion in the number of type 2 diabetes loci can be leveraged to identify such pathways. METHODS We developed a high-throughput pipeline to enable clustering of type 2 diabetes loci based on variant-trait associations. Our pipeline extracted summary statistics from genome-wide association studies (GWAS) for type 2 diabetes and related traits to generate a matrix of 323 variants × 64 trait associations and applied Bayesian non-negative matrix factorisation (bNMF) to identify genetic components of type 2 diabetes. Epigenomic enrichment analysis was performed in 28 cell types and single pancreatic cells. We generated cluster-specific polygenic scores and performed regression analysis in an independent cohort (N=25,419) to assess for clinical relevance. RESULTS We identified ten clusters of genetic loci, recapturing the five from our prior analysis as well as novel clusters related to beta cell dysfunction, pronounced insulin secretion, and levels of alkaline phosphatase, lipoprotein A and sex hormone-binding globulin. Four clusters related to mechanisms of insulin deficiency, five to insulin resistance and one had an unclear mechanism. The clusters displayed tissue-specific epigenomic enrichment, notably with the two beta cell clusters differentially enriched in functional and stressed pancreatic beta cell states. Additionally, cluster-specific polygenic scores were differentially associated with patient clinical characteristics and outcomes. The pipeline was applied to coronary artery disease and chronic kidney disease, identifying multiple overlapping clusters with type 2 diabetes. CONCLUSIONS/INTERPRETATION Our approach stratifies type 2 diabetes loci into physiologically interpretable genetic clusters associated with distinct tissues and clinical outcomes. The pipeline allows for efficient updating as additional GWAS become available and can be readily applied to other conditions, facilitating clinical translation of GWAS findings. Software to perform this clustering pipeline is freely available.
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Affiliation(s)
- Hyunkyung Kim
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Kenneth E Westerman
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Clinical and Translational Epidemiology Unit, Massachusetts General Hospital, Boston, MA, USA
| | - Kirk Smith
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Joshua Chiou
- Department of Pediatrics, University of California San Diego, San Diego, CA, USA
| | - Joanne B Cole
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Division of Endocrinology, Boston Children's Hospital, Boston, MA, USA
- Department of Biomedical Informatics, University of Colorado School of Medicine, Aurora, CO, USA
| | | | - Marcin von Grotthuss
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Takeda Pharmaceuticals, Cambridge, MA, USA
| | - Soo Heon Kwak
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jaegil Kim
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- GlaxoSmithKline, Cambridge, MA, USA
| | - Josep M Mercader
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Jose C Florez
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Kyle Gaulton
- Department of Pediatrics, University of California San Diego, San Diego, CA, USA
| | - Alisa K Manning
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Clinical and Translational Epidemiology Unit, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Miriam S Udler
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Department of Medicine, Harvard Medical School, Boston, MA, USA.
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22
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Scheen AJ, Lefèbvre PJ. Glucagon, from past to present: a century of intensive research and controversies. Lancet Diabetes Endocrinol 2023; 11:129-138. [PMID: 36566754 DOI: 10.1016/s2213-8587(22)00349-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 12/24/2022]
Abstract
2022 corresponds to the 100th anniversary of the discovery of glucagon. This TimeCapsule aims to recall the main steps leading to the discovery, characterisation, and clinical importance of the so-called second pancreatic hormone. We describe the early historical findings in basic research (ie, discovery, purification, structure, α-cell origin, radioimmunoassay, glucagon gene [GCG], and glucagon receptor [GLR]), in which three future Nobel Prize laureates were actively involved. Considered as an anti-insulin hormone, glucagon was rapidly used to treat insulin-induced hypoglycaemic coma episodes in people with type 1 diabetes. A key step in the story of glucagon was the discovery of its role and the role of α cells in the physiology and pathophysiology (ie, paracrinopathy) of type 2 diabetes. This concept led to the design of different strategies targeting glucagon, among which GLP-1 receptor (GLP1R) agonists were a major breakthrough, and combination of inhibition of glucagon secretion with stimulation of insulin secretion (both in a glucose-dependent manner). Taking advantage of the glucagon-induced increase in energy metabolism, biased coagonists were developed. Besides the GLP-1 receptor, these coagonists also target the glucagon receptor to further promote weight loss. Thus, the 100-year story of glucagon has most probably not come to an end.
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Affiliation(s)
- André J Scheen
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of medicine, CHU Liège, Liège University, Liège, Belgium.
| | - Pierre J Lefèbvre
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of medicine, CHU Liège, Liège University, Liège, Belgium
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23
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Feris F, McRae A, Kellogg TA, McKenzie T, Ghanem O, Acosta A. Mucosal and hormonal adaptations after Roux-en-Y gastric bypass. Surg Obes Relat Dis 2023; 19:37-49. [PMID: 36243547 PMCID: PMC9797451 DOI: 10.1016/j.soard.2022.08.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 01/12/2023]
Abstract
The aim of this study was to perform a comprehensive literature review regarding the relevant hormonal and histologic changes observed after Roux-en-Y gastric bypass (RYGB). We aimed to describe the relevant hormonal (glucagon-like peptides 1 and 2 [GLP-1 and GLP-2], peptide YY [PYY], oxyntomodulin [OXM], bile acids [BA], cholecystokinin [CCK], ghrelin, glucagon, gastric inhibitory polypeptide [GIP], and amylin) profiles, as well as the histologic (mucosal cellular) adaptations happening after patients undergo RYGB. Our review compiles the current evidence and furthers the understanding of the rationale behind the food intake regulatory adaptations occurring after RYGB surgery. We identify gaps in the literature where the potential for future investigations and therapeutics may lie. We performed a comprehensive database search without language restrictions looking for RYGB bariatric surgery outcomes in patients with pre- and postoperative blood work hormonal profiling and/or gut mucosal biopsies. We gathered the relevant study results and describe them in this review. Where human findings were lacking, we included animal model studies. The amalgamation of physiologic, metabolic, and cellular adaptations following RYGB is yet to be fully characterized. This constitutes a fundamental aspiration for enhancing and individualizing obesity therapy.
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Affiliation(s)
- Fauzi Feris
- Precision Medicine for Obesity Program, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Alison McRae
- Precision Medicine for Obesity Program, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Todd A Kellogg
- Division of Endocrine and Metabolic Surgery, Department of Surgery, Mayo Clinic, Rochester, Minnesota
| | - Travis McKenzie
- Division of Endocrine and Metabolic Surgery, Department of Surgery, Mayo Clinic, Rochester, Minnesota
| | - Omar Ghanem
- Division of Endocrine and Metabolic Surgery, Department of Surgery, Mayo Clinic, Rochester, Minnesota
| | - Andres Acosta
- Precision Medicine for Obesity Program, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
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24
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Freyberg Z, Gittes GK. Roles of Pancreatic Islet Catecholamine Neurotransmitters in Glycemic Control and in Antipsychotic Drug-Induced Dysglycemia. Diabetes 2023; 72:3-15. [PMID: 36538602 PMCID: PMC9797319 DOI: 10.2337/db22-0522] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/24/2022] [Indexed: 12/24/2022]
Abstract
Catecholamine neurotransmitters dopamine (DA) and norepinephrine (NE) are essential for a myriad of functions throughout the central nervous system, including metabolic regulation. These molecules are also present in the pancreas, and their study may shed light on the effects of peripheral neurotransmission on glycemic control. Though sympathetic innervation to islets provides NE that signals at local α-cell and β-cell adrenergic receptors to modify hormone secretion, α-cells and β-cells also synthesize catecholamines locally. We propose a model where α-cells and β-cells take up catecholamine precursors in response to postprandial availability, preferentially synthesizing DA. The newly synthesized DA signals in an autocrine/paracrine manner to regulate insulin and glucagon secretion and maintain glycemic control. This enables islets to couple local catecholamine signaling to changes in nutritional state. We also contend that the DA receptors expressed by α-cells and β-cells are targeted by antipsychotic drugs (APDs)-some of the most widely prescribed medications today. Blockade of local DA signaling contributes significantly to APD-induced dysglycemia, a major contributor to treatment discontinuation and development of diabetes. Thus, elucidating the peripheral actions of catecholamines will provide new insights into the regulation of metabolic pathways and may lead to novel, more effective strategies to tune metabolism and treat diabetes.
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Affiliation(s)
- Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
| | - George K. Gittes
- Division of Pediatric Surgery, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA
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25
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A randomized trial of oral gamma aminobutyric acid (GABA) or the combination of GABA with glutamic acid decarboxylase (GAD) on pancreatic islet endocrine function in children with newly diagnosed type 1 diabetes. Nat Commun 2022; 13:7928. [PMID: 36566274 PMCID: PMC9790014 DOI: 10.1038/s41467-022-35544-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/06/2022] [Indexed: 12/25/2022] Open
Abstract
Gamma aminobutyric acid(GABA) is synthesized by glutamate decarboxylase(GAD) in β-cells. Regarding Type 1 diabetes(T1D), animal/islet-cell studies found that GABA promotes insulin secretion, inhibits α-cell glucagon and dampens immune inflammation, while GAD immunization may also preserve β-cells. We evaluated the safety and efficacy of oral GABA alone, or combination GABA with GAD, on the preservation of residual insulin secretion in recent-onset T1D. Herein we report a single-center, double-blind, one-year, randomized trial in 97 children conducted March 2015 to June 2019(NCT02002130). Using a 2:1 treatment:placebo ratio, interventions included oral GABA twice-daily(n = 41), or oral GABA plus two-doses GAD-alum(n = 25), versus placebo(n = 31). The primary outcome, preservation of fasting/meal-stimulated c-peptide, was not attained. Of the secondary outcomes, the combination GABA/GAD reduced fasting and meal-stimulated serum glucagon, while the safety/tolerability of GABA was confirmed. There were no clinically significant differences in glycemic control or diabetes antibody titers. Given the low GABA dose for this pediatric trial, future investigations using higher-dose or long-acting GABA formulations, either alone or with GAD-alum, could be considered, although GABA alone or in combination with GAD-alum did nor preserve beta-cell function in this trial.
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26
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Small Hepatitis B Virus Surface Antigen Promotes Hepatic Gluconeogenesis via Enhancing Glucagon/cAMP/Protein Kinase A/CREB Signaling. J Virol 2022; 96:e0102022. [PMID: 36394315 PMCID: PMC9749458 DOI: 10.1128/jvi.01020-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Hepatitis B virus (HBV) is a major risk factor for serious liver diseases. The liver plays a unique role in controlling carbohydrate metabolism to maintain the glucose level within the normal range. Chronic HBV infection has been reported to associate with a high prevalence of diabetes. However, the detailed molecular mechanism underlying the potential association remains largely unknown. Here, we report that liver-targeted delivery of small HBV surface antigen (SHBs), the most abundant viral protein of HBV, could elevate blood glucose levels and impair glucose and insulin tolerance in mice by promoting hepatic gluconeogenesis. Hepatocytes with SHB expression also exhibited increased glucose production and expression of gluconeogenic genes glucose-6-phosphatase (G6pc) and phosphoenolpyruvate carboxykinase (PEPCK) in response to glucagon stimulation. Mechanistically, SHBs increased cellular levels of cyclic AMP (cAMP) and consequently activated protein kinase A (PKA) and its downstream effector cAMP-responsive element binding protein (CREB). SHBs-induced activation of CREB enhanced transcripts of gluconeogenic genes, thus promoting hepatic gluconeogenesis. The elevated cAMP level resulted from increased transcription activity and expression of adenylyl cyclase 1 (AC1) by SHBs through a binary E-box factor binding site (BEF). Taken together, we unveiled a novel pathogenic role and mechanism of SHBs in hepatic gluconeogenesis, and these results might highlight a potential target for preventive and therapeutic intervention in the development and progression of HBV-associated diabetes. IMPORTANCE Chronic HBV infection causes progressive liver damage and is found to be a risk factor for diabetes. However, the mechanism in the regulation of glucose metabolism by HBV remains to be established. In the current study, we demonstrate for the first time that the small hepatitis B virus surface antigen (SHBs) of HBV elevates AC1 transcription and expression to activate cAMP/PKA/CREB signaling and subsequently induces the expression of gluconeogenic genes and promotes hepatic gluconeogenesis both in vivo and in vitro. This study provides a direct link between HBV infection and diabetes and implicates that SHBs may represent a potential target for the treatment of HBV-induced metabolic disorders.
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27
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Capozzi ME, D'Alessio DA, Campbell JE. The past, present, and future physiology and pharmacology of glucagon. Cell Metab 2022; 34:1654-1674. [PMID: 36323234 PMCID: PMC9641554 DOI: 10.1016/j.cmet.2022.10.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/23/2022] [Accepted: 09/30/2022] [Indexed: 11/07/2022]
Abstract
The evolution of glucagon has seen the transition from an impurity in the preparation of insulin to the development of glucagon receptor agonists for use in type 1 diabetes. In type 2 diabetes, glucagon receptor antagonists have been explored to reduce glycemia thought to be induced by hyperglucagonemia. However, the catabolic actions of glucagon are currently being leveraged to target the rise in obesity that paralleled that of diabetes, bringing the pharmacology of glucagon full circle. During this evolution, the physiological importance of glucagon advanced beyond the control of hepatic glucose production, incorporating critical roles for glucagon to regulate both lipid and amino acid metabolism. Thus, it is unsurprising that the study of glucagon has left several paradoxes that make it difficult to distill this hormone down to a simplified action. Here, we describe the history of glucagon from the past to the present and suggest some direction to the future of this field.
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Affiliation(s)
- Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA
| | - David A D'Alessio
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA; Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC 27701, USA
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA; Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27701, USA.
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28
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Hædersdal S, Lund A, Nielsen-Hannerup E, Maagensen H, Forman JL, Holst JJ, Knop FK, Vilsbøll T. The glucagon receptor antagonist LY2409021 does not affect gastrointestinal-mediated glucose disposal or the incretin effect in individuals with and without type 2 diabetes. Eur J Endocrinol 2022; 187:507-518. [PMID: 35977072 DOI: 10.1530/eje-22-0291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 08/17/2022] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Gastrointestinal-mediated glucose disposal (GIGD) during oral glucose tolerance test (OGTT) reflects the percentage of glucose disposal caused by mechanisms elicited by the oral route of glucose administration. GIGD is reduced in patients with type 2 diabetes (T2D) due to a reduced incretin effect and possibly also due to inappropriate suppression of glucagon after oral glucose. We investigated the effect of glucagon receptor antagonism on GIGD, the incretin effect and glucose excursions in patients with T2D and controls without diabetes. DESIGN A double-blind, randomised, placebo-controlled crossover study was conducted. METHODS Ten patients with T2D and 10 gender-, age- and BMI-matched controls underwent two 50 g OGTTs and 2 isoglycaemic i.v. glucose infusions, succeeding (~10 h) single-dose administration of 100 mg of the glucagon receptor antagonist LY2409021 or placebo, respectively. RESULTS Compared to placebo, LY2409021 reduced fasting plasma glucose in patients with T2D and controls. Plasma glucose excursions after oral glucose assessed by baseline-subtracted area under the curve were increased by LY2409021 compared to placebo in both groups, but no effect of LY2409021 on GIGD or the incretin effect was observed. LY2409021 increased fasting glucagon concentrations three-fold compared to placebo concentrations. CONCLUSIONS Glucagon receptor antagonism with LY2409021 had no effect on the impaired GIGD or the impaired incretin effect in patients with T2D and did also not affect these parameters in the controls. Surprisingly, we observed reduced oral glucose tolerance with LY2409021 which may be specific for this glucagon receptor antagonist.
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Affiliation(s)
- Sofie Hædersdal
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
- Danish Diabetes Academy, Odense University Hospital, Odense, Denmark
| | - Asger Lund
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Elisabeth Nielsen-Hannerup
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Henrik Maagensen
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Julie L Forman
- Department of Public Health, Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip K Knop
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, 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
| | - Tina Vilsbøll
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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29
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Novel Therapies for Cardiometabolic Disease: Recent Findings in Studies with Hormone Peptide-Derived G Protein Coupled Receptor Agonists. Nutrients 2022; 14:nu14183775. [PMID: 36145148 PMCID: PMC9503433 DOI: 10.3390/nu14183775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/07/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
The increasing prevalence of obesity and type 2 diabetes (T2DM) is provoking an important socioeconomic burden mainly in the form of cardiovascular disease (CVD). One successful strategy is the so-called metabolic surgery whose beneficial effects are beyond dietary restrictions and weight loss. One key underlying mechanism behind this surgery is the cooperative improved action of the preproglucagon-derived hormones, glucagon, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) which exert their functions through G protein-coupled receptors (GPCR). Great success has been reached with therapies based on the GLP-1 receptor monoagonism; therefore, a logical and rational approach is the use of the dual and triagonism of GCPC to achieve complete metabolic homeostasis. The present review describes novel findings regarding the complex biology of the preproglucagon-derived hormones, their signaling, and the drug development of their analogues, especially those acting as dual and triagonists. Moreover, the main investigations into animal models and ongoing clinical trials using these unimolecular dual and triagonists are included which have demonstrated their safety, efficacy, and beneficial effects on the CV system. These therapeutic strategies could greatly impact the treatment of CVD with unprecedented benefits which will be revealed in the next years.
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30
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Maruszczak K, Rasmussen C, Ceutz FR, Ørgaard A, Elmelund E, Richter MM, Holst JJ, Winther-Sørensen M, Wewer Albrechtsen NJ. Arginine-induced glucagon secretion and glucagon-induced enhancement of amino acid catabolism are not influenced by ambient glucose levels in mice. Am J Physiol Endocrinol Metab 2022; 323:E207-E214. [PMID: 35830690 DOI: 10.1152/ajpendo.00122.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amino acids stimulate the secretion of glucagon, and glucagon receptor signaling regulates amino acid catabolism via ureagenesis, together constituting the liver-α cell axis. Impairment of the liver-α cell axis is observed in metabolic diseases such as diabetes. It is, however, unknown whether glucose affects the liver-α cell axis. We investigated the role of glucose on the liver-α cell axis in vivo and ex vivo. The isolated perfused mouse pancreas was used to evaluate the direct effect of low (3.5 mmol/L) and high (15 mmol/L) glucose levels on amino acid (10 mmol/L arginine)-induced glucagon secretion. High glucose levels alone lowered glucagon secretion, but the amino acid-induced glucagon responses were similar in high and low glucose conditions (P = 0.38). The direct effect of glucose on glucagon and amino acid-induced ureagenesis was assessed using isolated perfused mouse livers stimulated with a mixture of amino acids (VaminR, 10 mmol/L) and glucagon (10 nmol/L) during high and low glucose conditions. Urea production increased robustly but was independent of glucose levels (P = 0.95). To investigate the whole body effects of glucose on the liver-α cell axis, four groups of mice received intraperitoneal injections of glucose-Vamin (2 g/kg, + 3.5 µmol/g, respectively, G/V), saline-Vamin (S/V), glucose-saline (G/S), or saline-saline (S/S). Blood glucose did not differ significantly between G/S and G/V groups. Levels of glucagon and amino acids were similar in the G/V and S/V groups (P = 0.28). Amino acids may overrule the inhibitory effect of glucose on glucagon secretion and the liver-α cell axis may operate independently of glucose in mice.NEW & NOTEWORTHY Glucagon is an essential regulator of our metabolism. Recent evidence suggests that the physiological actions of glucagon reside in amino acid catabolism in the so-called liver-α cell axis, in which amino acids stimulate glucagon secretion and glucagon enhances hepatic amino acid catabolism. Here, it is demonstrated that this feedback system is independent of glycemia possibly explaining why hyperglycemia in diabetes may not suppress α cell secretion.
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Affiliation(s)
- Katharina Maruszczak
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
- Obesity Research Unit, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Christine Rasmussen
- Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Frederik R Ceutz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anne Ørgaard
- 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
| | - Emilie Elmelund
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael M Richter
- Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, 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
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department for Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department for Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
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31
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Habegger KM. Cross Talk Between Insulin and Glucagon Receptor Signaling in the Hepatocyte. Diabetes 2022; 71:1842-1851. [PMID: 35657690 PMCID: PMC9450567 DOI: 10.2337/dbi22-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022]
Abstract
While the consumption of external energy (i.e., feeding) is essential to life, this action induces a temporary disturbance of homeostasis in an animal. A primary example of this effect is found in the regulation of glycemia. In the fasted state, stored energy is released to maintain physiological glycemic levels. Liver glycogen is liberated to glucose, glycerol and (glucogenic) amino acids are used to build new glucose molecules (i.e., gluconeogenesis), and fatty acids are oxidized to fuel long-term energetic demands. This regulation is driven primarily by the counterregulatory hormones epinephrine, growth hormone, cortisol, and glucagon. Conversely, feeding induces a rapid influx of diverse nutrients, including glucose, that disrupt homeostasis. Consistently, a host of hormonal and neural systems under the coordination of insulin are engaged in the transition from fasting to prandial states to reduce this disruption. The ultimate action of these systems is to appropriately store the newly acquired energy and to return to the homeostatic norm. Thus, at first glance it is tempting to assume that glucagon is solely antagonistic regarding the anabolic effects of insulin. We have been intrigued by the role of glucagon in the prandial transition and have attempted to delineate its role as beneficial or inhibitory to glycemic control. The following review highlights this long-known yet poorly understood hormone.
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Affiliation(s)
- Kirk M. Habegger
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
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32
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Richter MM, Galsgaard KD, Elmelund E, Knop FK, Suppli MP, Holst JJ, Winther-Sørensen M, Kjeldsen SA, Wewer Albrechtsen NJ. The Liver-α-Cell Axis in Health and in Disease. Diabetes 2022; 71:1852-1861. [PMID: 35657688 PMCID: PMC9862287 DOI: 10.2337/dbi22-0004] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/19/2022] [Indexed: 02/05/2023]
Abstract
Glucagon and insulin are the main regulators of blood glucose. While the actions of insulin are extensively mapped, less is known about glucagon. Besides glucagon's role in glucose homeostasis, there are additional links between the pancreatic α-cells and the hepatocytes, often collectively referred to as the liver-α-cell axis, that may be of importance for health and disease. Thus, glucagon receptor antagonism (pharmacological or genetic), which disrupts the liver-α-cell axis, results not only in lower fasting glucose but also in reduced amino acid turnover and dyslipidemia. Here, we review the actions of glucagon on glucose homeostasis, amino acid catabolism, and lipid metabolism in the context of the liver-α-cell axis. The concept of glucagon resistance is also discussed, and we argue that the various elements of the liver-α-cell axis may be differentially affected in metabolic diseases such as diabetes, obesity, and nonalcoholic fatty liver disease (NAFLD). This conceptual rethinking of glucagon biology may explain why patients with type 2 diabetes have hyperglucagonemia and how NAFLD disrupts the liver-α-cell axis, compromising the normal glucagon-mediated enhancement of substrate-induced amino acid turnover and possibly fatty acid β-oxidation. In contrast to amino acid catabolism, glucagon-induced glucose production may not be affected by NAFLD, explaining the diabetogenic effect of NAFLD-associated hyperglucagonemia. Consideration of the liver-α-cell axis is essential to understanding the complex pathophysiology underlying diabetes and other metabolic diseases.
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Affiliation(s)
- Michael M. Richter
- Department of Clinical Biochemistry, Diagnostic Center, Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Katrine D. Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emilie Elmelund
- Department of Biomedical Sciences, 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
- 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
- Steno Diabetes Center Copenhagen, Herlev, Denmark
| | - Malte P. Suppli
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, 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
| | - Marie Winther-Sørensen
- Novo Nordisk Foundation Center for Protein 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
| | - Sasha A.S. Kjeldsen
- Novo Nordisk Foundation Center for Protein 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
| | - Nicolai J. Wewer Albrechtsen
- Department of Clinical Biochemistry, Diagnostic Center, Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein 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
- Department of Clinical Biochemistry, Copenhagen University Hospital—Bispebjerg and Frederiksberg Hospital, Bispebjerg, Denmark
- Corresponding author: Nicolai J. Wewer Albrechtsen,
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Laurenti MC, Arora P, Dalla Man C, Andrews JC, Rizza RA, Matveyenko A, Bailey KR, Cobelli C, Vella A. The relationship between insulin and glucagon concentrations in non-diabetic humans. Physiol Rep 2022; 10:e15380. [PMID: 35822422 PMCID: PMC9277417 DOI: 10.14814/phy2.15380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/13/2022] [Accepted: 06/17/2022] [Indexed: 06/02/2023] Open
Abstract
Abnormal postprandial suppression of glucagon in Type 2 diabetes (T2DM) has been attributed to impaired insulin secretion. Prior work suggests that insulin and glucagon show an inverse coordinated relationship. However, dysregulation of α-cell function in prediabetes occurs early and independently of changes in β-cells, which suggests insulin having a less significant role on glucagon control. We therefore, sought to examine whether hepatic vein hormone concentrations provide evidence to further support the modulation of glucagon secretion by insulin. As part of a series of experiments to measure the effect of diabetes-associated genetic variation in TCF7L2 on islet cell function, hepatic vein insulin and glucagon concentrations were measured at 2-minute intervals during fasting and a hyperglycemic clamp. The experiment was performed on 29 nondiabetic subjects (age = 46 ± 2 years, BMI 28 ± 1 Kg/m2 ) and enabled post-hoc analysis, using Cross-Correlation and Cross-Approximate Entropy (Cross-ApEn) to evaluate the interaction of insulin and glucose. Mean insulin concentrations rose from fasting (33 ± 4 vs. 146 ± 12 pmol/L, p < 0.01) while glucagon was suppressed (96 ± 8 vs. 62 ± 5 ng/L, p < 0.01) during the clamp. Cross-ApEn was used to measure pattern reproducibility in the two hormones using glucagon as control mechanism (0.78 ± 0.03 vs. 0.76 ± 0.03, fasting vs. hyperglycemia) and using insulin as a control mechanism (0.78 ± 0.02 vs. 0.76 ± 0.03, fasting vs. hyperglycemia). Values did not differ between the two scenarios. Cross-correlation analysis demonstrated a small in-phase coordination between insulin and glucagon concentrations during fasting, which inverted during hyperglycemia. This data suggests that the interaction between the two hormones is not driven by either. On a minute-to-minute basis, direct control and secretion of glucagon is not mediated (or restrained) by insulin.
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Affiliation(s)
- Marcello C. Laurenti
- Division of Endocrinology, Diabetes & MetabolismEndocrine Research Unit, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
- Biomedical Engineering and Physiology Graduate Program, Mayo Clinic Graduate School of Biomedical SciencesRochesterMinnesotaUSA
| | - Praveer Arora
- Division of Endocrinology, Diabetes & MetabolismEndocrine Research Unit, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
| | - Chiara Dalla Man
- Department of Information EngineeringUniversity of PadovaPadovaItaly
| | - James C. Andrews
- Vascular and Interventional Radiology, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
| | - Robert A. Rizza
- Division of Endocrinology, Diabetes & MetabolismEndocrine Research Unit, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
| | - Aleksey Matveyenko
- Division of Endocrinology, Diabetes & MetabolismEndocrine Research Unit, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
| | - Kent R. Bailey
- Division of Biomedical Statistics and Informatics, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
| | - Claudio Cobelli
- Department of Woman and Child's HealthUniversity of PadovaPadovaItaly
| | - Adrian Vella
- Division of Endocrinology, Diabetes & MetabolismEndocrine Research Unit, Mayo Clinic, College of Medicine and ScienceRochesterMinnesotaUSA
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34
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Zhang J, Pivovarova-Ramich O, Kabisch S, Markova M, Hornemann S, Sucher S, Rohn S, Machann J, Pfeiffer AFH. High Protein Diets Improve Liver Fat and Insulin Sensitivity by Prandial but Not Fasting Glucagon Secretion in Type 2 Diabetes. Front Nutr 2022; 9:808346. [PMID: 35662921 PMCID: PMC9160603 DOI: 10.3389/fnut.2022.808346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Glucagon (GCGN) plays a key role in glucose and amino acid (AA) metabolism by increasing hepatic glucose output. AA strongly stimulate GCGN secretion which regulates hepatic AA degradation by ureagenesis. Although increased fasting GCGN levels cause hyperglycemia GCGN has beneficial actions by stimulating hepatic lipolysis and improving insulin sensitivity through alanine induced activation of AMPK. Indeed, stimulating prandial GCGN secretion by isocaloric high protein diets (HPDs) strongly reduces intrahepatic lipids (IHLs) and improves glucose metabolism in type 2 diabetes mellitus (T2DM). Therefore, the role of GCGN and circulating AAs in metabolic improvements in 31 patients with T2DM consuming HPD was investigated. Six weeks HPD strongly coordinated GCGN and AA levels with IHL and insulin sensitivity as shown by significant correlations compared to baseline. Reduction of IHL during the intervention by 42% significantly improved insulin sensitivity [homeostatic model assessment for insulin resistance (HOMA-IR) or hyperinsulinemic euglycemic clamps] but not fasting GCGN or AA levels. By contrast, GCGN secretion in mixed meal tolerance tests (MMTTs) decreased depending on IHL reduction together with a selective reduction of GCGN-regulated alanine levels indicating greater GCGN sensitivity. HPD aligned glucose metabolism with GCGN actions. Meal stimulated, but not fasting GCGN, was related to reduced liver fat and improved insulin sensitivity. This supports the concept of GCGN-induced hepatic lipolysis and alanine- and ureagenesis-induced activation of AMPK by HPD.
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Affiliation(s)
- Jiudan Zhang
- Department of Endocrinology, Diabetes and Nutrition, Charité – Universitätsmedizin Berlin, Berlin, Germany
- *Correspondence: Jiudan Zhang,
| | - Olga Pivovarova-Ramich
- Department of Endocrinology, Diabetes and Nutrition, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Potsdam, Germany
- Deutsches Zentrum für Diabetesforschung (DZD), Neuherberg, Germany
| | - Stefan Kabisch
- Department of Endocrinology, Diabetes and Nutrition, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Potsdam, Germany
- Deutsches Zentrum für Diabetesforschung (DZD), Neuherberg, Germany
| | - Mariya Markova
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Potsdam, Germany
- Deutsches Zentrum für Diabetesforschung (DZD), Neuherberg, Germany
| | - Silke Hornemann
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Potsdam, Germany
- Deutsches Zentrum für Diabetesforschung (DZD), Neuherberg, Germany
| | - Stephanie Sucher
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Potsdam, Germany
| | - Sascha Rohn
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Hamburg, Germany
- Faculty of Process Sciences, Institute of Food Technology and Food Chemistry, Technical University of Berlin, Berlin, Germany
| | - Jürgen Machann
- Deutsches Zentrum für Diabetesforschung (DZD), Neuherberg, Germany
- Section on Experimental Radiology, Department of Diagnostic and Interventional Radiology, University Hospital, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
| | - Andreas F. H. Pfeiffer
- Department of Endocrinology, Diabetes and Nutrition, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Deutsches Zentrum für Diabetesforschung (DZD), Neuherberg, Germany
- Andreas F. H. Pfeiffer,
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35
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Angelidi AM, Belanger MJ, Kokkinos A, Koliaki CC, Mantzoros CS. Novel Noninvasive Approaches to the Treatment of Obesity: From Pharmacotherapy to Gene Therapy. Endocr Rev 2022; 43:507-557. [PMID: 35552683 PMCID: PMC9113190 DOI: 10.1210/endrev/bnab034] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Indexed: 02/08/2023]
Abstract
Recent insights into the pathophysiologic underlying mechanisms of obesity have led to the discovery of several promising drug targets and novel therapeutic strategies to address the global obesity epidemic and its comorbidities. Current pharmacologic options for obesity management are largely limited in number and of modest efficacy/safety profile. Therefore, the need for safe and more efficacious new agents is urgent. Drugs that are currently under investigation modulate targets across a broad range of systems and tissues, including the central nervous system, gastrointestinal hormones, adipose tissue, kidney, liver, and skeletal muscle. Beyond pharmacotherapeutics, other potential antiobesity strategies are being explored, including novel drug delivery systems, vaccines, modulation of the gut microbiome, and gene therapy. The present review summarizes the pathophysiology of energy homeostasis and highlights pathways being explored in the effort to develop novel antiobesity medications and interventions but does not cover devices and bariatric methods. Emerging pharmacologic agents and alternative approaches targeting these pathways and relevant research in both animals and humans are presented in detail. Special emphasis is given to treatment options at the end of the development pipeline and closer to the clinic (ie, compounds that have a higher chance to be added to our therapeutic armamentarium in the near future). Ultimately, advancements in our understanding of the pathophysiology and interindividual variation of obesity may lead to multimodal and personalized approaches to obesity treatment that will result in safe, effective, and sustainable weight loss until the root causes of the problem are identified and addressed.
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Affiliation(s)
- Angeliki M Angelidi
- Section of Endocrinology, VA Boston Healthcare System, Harvard Medical School, Boston, MA, USA
- Department of Medicine Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Matthew J Belanger
- Department of Medicine Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Alexander Kokkinos
- First Department of Propaedeutic Medicine, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, Athens, Greece
| | - Chrysi C Koliaki
- First Department of Propaedeutic Medicine, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, Athens, Greece
| | - Christos S Mantzoros
- Section of Endocrinology, VA Boston Healthcare System, Harvard Medical School, Boston, MA, USA
- Department of Medicine Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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36
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Intermittent protein restriction protects islet β cells and improves glucose homeostasis in diabetic mice. Sci Bull (Beijing) 2022; 67:733-747. [PMID: 36546138 DOI: 10.1016/j.scib.2021.12.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/15/2021] [Accepted: 12/09/2021] [Indexed: 01/06/2023]
Abstract
Diabetes is caused by the interplay between genetics and environmental factors, tightly linked to lifestyle and dietary patterns. In this study, we explored the effectiveness of intermittent protein restriction (IPR) in diabetes control. IPR drastically reduced hyperglycemia in both streptozotocin-treated and leptin receptor-deficient db/db mouse models. IPR improved the number, proliferation, and function of β cells in pancreatic islets. IPR reduced glucose production in the liver and elevated insulin signaling in the skeletal muscle. IPR elevated serum level of FGF21, and deletion of the Fgf21 gene in the liver abrogated the hypoglycemic effect of IPR without affecting β cells. IPR caused less lipid accumulation and damage in the liver than that caused by continuous protein restriction in streptozotocin-treated mice. Single-cell RNA sequencing using mouse islets revealed that IPR reversed diabetes-associated β cell reduction and immune cell accumulation. As IPR is not based on calorie restriction and is highly effective in glycemic control and β cell protection, it has promising translational potential in the future.
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Higgs JA, Quinn AP, Seely KD, Richards Z, Mortensen SP, Crandall CS, Brooks AE. Pathophysiological Link between Insulin Resistance and Adrenal Incidentalomas. Int J Mol Sci 2022; 23:ijms23084340. [PMID: 35457158 PMCID: PMC9032410 DOI: 10.3390/ijms23084340] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/05/2022] [Accepted: 04/12/2022] [Indexed: 12/22/2022] Open
Abstract
Adrenal incidentalomas are incidentally discovered adrenal masses greater than one centimeter in diameter. An association between insulin resistance and adrenal incidentalomas has been established. However, the pathophysiological link between these two conditions remains incompletely characterized. This review examines the literature on the interrelationship between insulin resistance and adrenal masses, their subtypes, and related pathophysiology. Some studies show that functional and non-functional adrenal masses elicit systemic insulin resistance, whereas others conclude the inverse. Insulin resistance, hyperinsulinemia, and the anabolic effects on adrenal gland tissue, which have insulin and insulin-like growth factor-1 receptors, offer possible pathophysiological links. Conversely, autonomous adrenal cortisol secretion generates visceral fat accumulation and insulin resistance. Further investigation into the mechanisms and timing of these two pathologies as they relate to one another is needed and could be valuable in the prevention, detection, and treatment of both conditions.
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Affiliation(s)
- Jordan A. Higgs
- College of Osteopathic Medicine, Rocky Vista University, Ivins, UT 84738, USA; (J.A.H.); (A.P.Q.); (Z.R.); (S.P.M.); (C.S.C.)
| | - Alyssa P. Quinn
- College of Osteopathic Medicine, Rocky Vista University, Ivins, UT 84738, USA; (J.A.H.); (A.P.Q.); (Z.R.); (S.P.M.); (C.S.C.)
| | - Kevin D. Seely
- College of Osteopathic Medicine, Rocky Vista University, Ivins, UT 84738, USA; (J.A.H.); (A.P.Q.); (Z.R.); (S.P.M.); (C.S.C.)
- Correspondence:
| | - Zeke Richards
- College of Osteopathic Medicine, Rocky Vista University, Ivins, UT 84738, USA; (J.A.H.); (A.P.Q.); (Z.R.); (S.P.M.); (C.S.C.)
| | - Shad P. Mortensen
- College of Osteopathic Medicine, Rocky Vista University, Ivins, UT 84738, USA; (J.A.H.); (A.P.Q.); (Z.R.); (S.P.M.); (C.S.C.)
| | - Cody S. Crandall
- College of Osteopathic Medicine, Rocky Vista University, Ivins, UT 84738, USA; (J.A.H.); (A.P.Q.); (Z.R.); (S.P.M.); (C.S.C.)
| | - Amanda E. Brooks
- Department of Research and Scholarly Activity, Rocky Vista University, Ivins, UT 84738, USA;
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38
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Zmazek J, Grubelnik V, Markovič R, Marhl M. Modeling the Amino Acid Effect on Glucagon Secretion from Pancreatic Alpha Cells. Metabolites 2022; 12:metabo12040348. [PMID: 35448534 PMCID: PMC9028923 DOI: 10.3390/metabo12040348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/29/2022] Open
Abstract
Type 2 Diabetes Mellitus (T2DM) is a burdensome problem in modern society, and intensive research is focused on better understanding the underlying cellular mechanisms of hormone secretion for blood glucose regulation. T2DM is a bi-hormonal disease, and in addition to 100 years of increasing knowledge about the importance of insulin, the second hormone glucagon, secreted by pancreatic alpha cells, is becoming increasingly important. We have developed a mathematical model for glucagon secretion that incorporates all major metabolic processes of glucose, fatty acids, and glutamine as the most abundant postprandial amino acid in blood. In addition, we consider cAMP signaling in alpha cells. The model predictions quantitatively estimate the relative importance of specific metabolic and signaling pathways and particularly emphasize the important role of glutamine in promoting glucagon secretion, which is in good agreement with known experimental data.
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Affiliation(s)
- Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia; (J.Z.); (R.M.)
| | - Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia;
| | - Rene Markovič
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia; (J.Z.); (R.M.)
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia;
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia; (J.Z.); (R.M.)
- Faculty of Education, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
- Correspondence:
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39
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Kettunen JLT, Rantala E, Dwivedi OP, Isomaa B, Sarelin L, Kokko P, Hakaste L, Miettinen PJ, Groop LC, Tuomi T. A multigenerational study on phenotypic consequences of the most common causal variant of HNF1A-MODY. Diabetologia 2022; 65:632-643. [PMID: 34951657 PMCID: PMC8894160 DOI: 10.1007/s00125-021-05631-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/04/2021] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS Systematic studies on the phenotypic consequences of variants causal of HNF1A-MODY are rare. Our aim was to assess the phenotype of carriers of a single HNF1A variant and genetic and clinical factors affecting the clinical spectrum. METHODS We conducted a family-based multigenerational study by comparing heterozygous carriers of the HNF1A p.(Gly292fs) variant with the non-carrier relatives irrespective of diabetes status. During more than two decades, 145 carriers and 131 non-carriers from 12 families participated in the study, and 208 underwent an OGTT at least once. We assessed the polygenic risk score for type 2 diabetes, age at onset of diabetes and measures of body composition, as well as plasma glucose, serum insulin, proinsulin, C-peptide, glucagon and NEFA response during the OGTT. RESULTS Half of the carriers remained free of diabetes at 23 years, one-third at 33 years and 13% even at 50 years. The median age at diagnosis was 21 years (IQR 17-35). We could not identify clinical factors affecting the age at conversion; sex, BMI, insulin sensitivity or parental carrier status had no significant effect. However, for 1 SD unit increase of a polygenic risk score for type 2 diabetes, the predicted age at diagnosis decreased by 3.2 years. During the OGTT, the carriers had higher levels of plasma glucose and lower levels of serum insulin and C-peptide than the non-carriers. The carriers were also leaner than the non-carriers (by 5.0 kg, p=0.012, and by 2.1 kg/m2 units of BMI, p=2.2 × 10-4, using the first adult measurements) and, possibly as a result of insulin deficiency, demonstrated higher lipolytic activity (with medians of NEFA at fasting 621 vs 441 μmol/l, p=0.0039; at 120 min during an OGTT 117 vs 64 μmol/l, p=3.1 × 10-5). CONCLUSIONS/INTERPRETATION The most common causal variant of HNF1A-MODY, p.(Gly292fs), presents not only with hyperglycaemia and insulin deficiency, but also with increased lipolysis and markedly lower adult BMI. Serum insulin was more discriminative than C-peptide between carriers and non-carriers. A considerable proportion of carriers develop diabetes after young adulthood. Even among individuals with a monogenic form of diabetes, polygenic risk of diabetes modifies the age at onset of diabetes.
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Affiliation(s)
- Jarno L T Kettunen
- Folkhälsan Research Center, Helsinki, Finland
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Department of Endocrinology, Abdominal Center, Helsinki University Hospital, Helsinki, Finland
- Research Programs Unit, Clinical and Molecular Metabolism, University of Helsinki, Helsinki, Finland
| | | | - Om P Dwivedi
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Bo Isomaa
- Folkhälsan Research Center, Helsinki, Finland
| | | | - Paula Kokko
- Folkhälsan Research Center, Helsinki, Finland
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Research Programs Unit, Clinical and Molecular Metabolism, University of Helsinki, Helsinki, Finland
| | - Liisa Hakaste
- Folkhälsan Research Center, Helsinki, Finland
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Department of Endocrinology, Abdominal Center, Helsinki University Hospital, Helsinki, Finland
- Research Programs Unit, Clinical and Molecular Metabolism, University of Helsinki, Helsinki, Finland
| | - Päivi J Miettinen
- New Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, and Biomedicum Stem Cell Center, University of Helsinki, Helsinki, Finland
| | - Leif C Groop
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
| | - Tiinamaija Tuomi
- Folkhälsan Research Center, Helsinki, Finland.
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.
- Department of Endocrinology, Abdominal Center, Helsinki University Hospital, Helsinki, Finland.
- Research Programs Unit, Clinical and Molecular Metabolism, University of Helsinki, Helsinki, Finland.
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
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40
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Armour SL, Frueh A, Knudsen JG. Sodium, Glucose and Dysregulated Glucagon Secretion: The Potential of Sodium Glucose Transporters. Front Pharmacol 2022; 13:837664. [PMID: 35237171 PMCID: PMC8882857 DOI: 10.3389/fphar.2022.837664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/26/2022] [Indexed: 01/01/2023] Open
Abstract
Diabetes is defined by hyperglycaemia due to progressive insulin resistance and compromised insulin release. In parallel, alpha cells develop dysregulation of glucagon secretion. Diabetic patients have insufficient glucagon secretion during hypoglycaemia and a lack of inhibition of glucagon secretion at higher blood glucose levels resulting in postprandial hyperglucagonaemia, which contributes to the development of hyperglycaemia. Sodium-glucose co-transporter 2 (SGLT2) inhibitors are an efficient pharmacologic approach for the treatment of hyperglycaemia in type 2 diabetes. While SGLT2 inhibitors aim at increasing glycosuria to decrease blood glucose levels, these inhibitors also increase circulating glucagon concentrations. Here, we review recent advances in our understanding of how SGLTs are involved in the regulation of glucagon secretion. Sodium plays an important role for alpha cell function, and a tight regulation of intracellular sodium levels is important for maintaining plasma membrane potential and intracellular pH. This involves the sodium-potassium pump, sodium-proton exchangers and SGLTs. While the expression of SGLT2 in alpha cells remains controversial, SGLT1 seems to play a central role for alpha cell function. Under hyperglycaemic conditions, SGLT1 mediated accumulation of sodium results in alpha cell dysregulation due to altered cellular acidification and ATP production. Taken together, this suggests that SGLT1 could be a promising, yet highly underappreciated drug target to restore alpha cell function and improve treatment of both type 1 and 2 diabetes.
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Affiliation(s)
| | | | - Jakob G. Knudsen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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41
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Cabrera O, Ficorilli J, Shaw J, Echeverri F, Schwede F, Chepurny OG, Leech CA, Holz GG. Intra-islet glucagon confers β-cell glucose competence for first-phase insulin secretion and favors GLP-1R stimulation by exogenous glucagon. J Biol Chem 2022; 298:101484. [PMID: 34896391 PMCID: PMC8789663 DOI: 10.1016/j.jbc.2021.101484] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 02/07/2023] Open
Abstract
We report that intra-islet glucagon secreted from α-cells signals through β-cell glucagon and GLP-1 receptors (GcgR and GLP-1R), thereby conferring to rat islets their competence to exhibit first-phase glucose-stimulated insulin secretion (GSIS). Thus, in islets not treated with exogenous glucagon or GLP-1, first-phase GSIS is abolished by a GcgR antagonist (LY2786890) or a GLP-1R antagonist (Ex[9-39]). Mechanistically, glucose competence in response to intra-islet glucagon is conditional on β-cell cAMP signaling because it is blocked by the cAMP antagonist prodrug Rp-8-Br-cAMPS-pAB. In its role as a paracrine hormone, intra-islet glucagon binds with high affinity to the GcgR, while also exerting a "spillover" effect to bind with low affinity to the GLP-1R. This produces a right shift of the concentration-response relationship for the potentiation of GSIS by exogenous glucagon. Thus, 0.3 nM glucagon fails to potentiate GSIS, as expected if similar concentrations of intra-islet glucagon already occupy the GcgR. However, 10 to 30 nM glucagon effectively engages the β-cell GLP-1R to potentiate GSIS, an action blocked by Ex[9-39] but not LY2786890. Finally, we report that the action of intra-islet glucagon to support insulin secretion requires a step-wise increase of glucose concentration to trigger first-phase GSIS. It is not measurable when GSIS is stimulated by a gradient of increasing glucose concentrations, as occurs during an oral glucose tolerance test in vivo. Collectively, such findings are understandable if defective intra-islet glucagon action contributes to the characteristic loss of first-phase GSIS in an intravenous glucose tolerance test that is diagnostic of type 2 diabetes in the clinical setting.
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Affiliation(s)
- Over Cabrera
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA.
| | - James Ficorilli
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Janice Shaw
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | | | - Frank Schwede
- Biolog Life Science Institute GmbH & Co KG, Bremen, Germany
| | - Oleg G Chepurny
- Department of Medicine, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA
| | - Colin A Leech
- Department of Medicine, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA
| | - George G Holz
- Department of Medicine, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA; Department of Pharmacology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
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42
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Pan A, Sun XM, Huang FQ, Liu JF, Cai YY, Wu X, Alolga RN, Li P, Liu BL, Liu Q, Qi LW. The mitochondrial β-oxidation enzyme HADHA restrains hepatic glucagon response by promoting β-hydroxybutyrate production. Nat Commun 2022; 13:386. [PMID: 35046401 PMCID: PMC8770464 DOI: 10.1038/s41467-022-28044-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 01/06/2022] [Indexed: 11/09/2022] Open
Abstract
Disordered hepatic glucagon response contributes to hyperglycemia in diabetes. The regulators involved in glucagon response are less understood. This work aims to investigate the roles of mitochondrial β-oxidation enzyme HADHA and its downstream ketone bodies in hepatic glucagon response. Here we show that glucagon challenge impairs expression of HADHA. Liver-specific HADHA overexpression reversed hepatic gluconeogenesis in mice, while HADHA knockdown augmented glucagon response. Stable isotope tracing shows that HADHA promotes ketone body production via β-oxidation. The ketone body β-hydroxybutyrate (BHB) but not acetoacetate suppresses gluconeogenesis by selectively inhibiting HDAC7 activity via interaction with Glu543 site to facilitate FOXO1 nuclear exclusion. In HFD-fed mice, HADHA overexpression improved metabolic disorders, and these effects are abrogated by knockdown of BHB-producing enzyme. In conclusion, BHB is responsible for the inhibitory effect of HADHA on hepatic glucagon response, suggesting that HADHA activation or BHB elevation by pharmacological intervention hold promise in treating diabetes.
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Affiliation(s)
- An Pan
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Xiao-Meng Sun
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Feng-Qing Huang
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Jin-Feng Liu
- Clinical Metabolomics Center, China Pharmaceutical University, Nanjing, 211198, China
| | - Yuan-Yuan Cai
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Xin Wu
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Raphael N Alolga
- Clinical Metabolomics Center, China Pharmaceutical University, Nanjing, 211198, China
| | - Ping Li
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Bao-Lin Liu
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Qun Liu
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
- Clinical Metabolomics Center, China Pharmaceutical University, Nanjing, 211198, China.
| | - Lian-Wen Qi
- State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
- Clinical Metabolomics Center, China Pharmaceutical University, Nanjing, 211198, China.
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Langlois A, Dumond A, Vion J, Pinget M, Bouzakri K. Crosstalk Communications Between Islets Cells and Insulin Target Tissue: The Hidden Face of Iceberg. Front Endocrinol (Lausanne) 2022; 13:836344. [PMID: 35185804 PMCID: PMC8851682 DOI: 10.3389/fendo.2022.836344] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/06/2022] [Indexed: 12/11/2022] Open
Abstract
The regulation of insulin secretion is under control of a complex inter-organ/cells crosstalk involving various metabolites and/or physical connections. In this review, we try to illustrate with current knowledge how β-cells communicate with other cell types and organs in physiological and pathological contexts. Moreover, this review will provide a better understanding of the microenvironment and of the context in which β-cells exist and how this can influence their survival and function. Recent studies showed that β-cell insulin secretion is regulated also by a direct and indirect inter-organ/inter-cellular communication involving various factors, illustrating the idea of "the hidden face of the iceberg". Moreover, any disruption on the physiological communication between β-cells and other cells or organs can participate on diabetes onset. Therefore, for new anti-diabetic treatments' development, it is necessary to consider the entire network of cells and organs involved in the regulation of β-cellular function and no longer just β-cell or pancreatic islet alone. In this context, we discuss here the intra-islet communication, the β-cell/skeletal muscle, β-cell/adipose tissue and β-cell/liver cross talk.
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Jia Y, Liu Y, Feng L, Sun S, Sun G. Role of Glucagon and Its Receptor in the Pathogenesis of Diabetes. Front Endocrinol (Lausanne) 2022; 13:928016. [PMID: 35784565 PMCID: PMC9243425 DOI: 10.3389/fendo.2022.928016] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/13/2022] [Indexed: 11/24/2022] Open
Abstract
Various theories for the hormonal basis of diabetes have been proposed and debated over the past few decades. Insulin insufficiency was previously regarded as the only hormone deficiency directly leading to metabolic disorders associated with diabetes. Although glucagon and its receptor are ignored in this framework, an increasing number of studies have shown that they play essential roles in the development and progression of diabetes. However, the molecular mechanisms underlying the effects of glucagon are still not clear. In this review, recent research on the mechanisms by which glucagon and its receptor contribute to the pathogenesis of diabetes as well as correlations between GCGR mutation rates in populations and the occurrence of diabetes are summarized. Furthermore, we summarize how recent research clearly establishes glucagon as a potential therapeutic target for diabetes.
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Affiliation(s)
- Yunbo Jia
- Innovative Engineering Technology Research Center for Cell Therapy, Shengjing Hospital of China Medical University, Shenyang, China
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yang Liu
- Innovative Engineering Technology Research Center for Cell Therapy, Shengjing Hospital of China Medical University, Shenyang, China
| | - Linlin Feng
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Siyu Sun
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
- *Correspondence: Siyu Sun, ; Guangwei Sun,
| | - Guangwei Sun
- Innovative Engineering Technology Research Center for Cell Therapy, Shengjing Hospital of China Medical University, Shenyang, China
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
- *Correspondence: Siyu Sun, ; Guangwei Sun,
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Wagner R, Eckstein SS, Fritsche L, Prystupa K, Hörber S, Häring HU, Birkenfeld AL, Peter A, Fritsche A, Heni M. Postprandial Dynamics of Proglucagon Cleavage Products and Their Relation to Metabolic Health. Front Endocrinol (Lausanne) 2022; 13:892677. [PMID: 35872982 PMCID: PMC9297683 DOI: 10.3389/fendo.2022.892677] [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: 03/09/2022] [Accepted: 05/24/2022] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION While oral glucose ingestion typically leads to a decrease in circulating glucagon levels, a substantial number of persons display stable or rising glucagon concentrations when assessed by radioimmunoassay (RIA). However, these assays show cross-reactivity to other proglucagon cleavage products. Recently, more specific assays became available, therefore we systematically assessed glucagon and other proglucagon cleavage products and their relation to metabolic health. RESEARCH DESIGN AND METHODS We used samples from 52 oral glucose tolerance tests (OGTT) that were randomly selected from persons with different categories of glucose tolerance in an extensively phenotyped study cohort. RESULTS Glucagon concentrations quantified with RIA were non-suppressed at 2 hours of the OGTT in 36% of the samples. Non-suppressors showed lower fasting glucagon levels compared to suppressors (p=0.011). Similar to RIA measurements, ELISA-derived fasting glucagon was lower in non-suppressors (p<0.001). Glucagon 1-61 as well as glicentin and GLP-1 kinetics were significantly different between suppressors and non-suppressors (p=0.004, p=0.002, p=0.008 respectively) with higher concentrations of all three hormones in non-suppressors. Levels of insulin, C-peptide, and free fatty acids were comparable between groups. Non-suppressors were leaner and had lower plasma glucose concentrations (p=0.03 and p=0.047, respectively). Despite comparable liver fat content and insulin sensitivity (p≥0.3), they had lower 2-hour post-challenge glucose (p=0.01). CONCLUSIONS Glucagon 1-61, glicentin and GLP-1 partially account for RIA-derived glucagon measurements due to cross-reactivity of the assay. However, this contribution is small, since the investigated proglucagon cleavage products contribute less than 10% to the variation in RIA measured glucagon. Altered glucagon levels and higher post-challenge incretins are associated with a healthier metabolic phenotype.
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Affiliation(s)
- Robert Wagner
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
- Department of Endocrinology and Diabetology, Medical Faculty and University Hospital, Heinrich Heine University, Düsseldorf, Germany
- Institute for Clinical Diabetology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich-Heine University, Düsseldorf, Germany
| | - Sabine S. Eckstein
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Louise Fritsche
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Katsiaryna Prystupa
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Sebastian Hörber
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Hans-Ulrich Häring
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Andreas L. Birkenfeld
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Andreas Peter
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Andreas Fritsche
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Martin Heni
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital Tübingen, Tübingen, Germany
- Division of Endocrinology and Diabetology, Department of Internal Medicine 1, University Hospital Ulm, Ulm, Germany
- *Correspondence: Martin Heni,
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Bisgaard Bengtsen M, Møller N. Mini-review: Glucagon responses in type 1 diabetes - a matter of complexity. Physiol Rep 2021; 9:e15009. [PMID: 34405569 PMCID: PMC8371343 DOI: 10.14814/phy2.15009] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 07/29/2021] [Indexed: 12/14/2022] Open
Abstract
In recent years the role of altered alpha cell function and glucagon secretion in type 1 diabetes has attracted scientific attention. It is well established that glucagon responses to hypoglycemia are absent in type 1 diabetes, but more uncertain whether it is intact following other physiological and metabolic stimuli compared with nondiabetic individuals. The aim of this review is to (i) summarize current knowledge on glucagon responses during hypoglycemia in normal physiology and type 1 diabetes, and (ii) review human in vivo studies investigating glucagon responses after other stimuli in individuals with type 1 diabetes and nondiabetic individuals. Available data suggest that in type 1 diabetes the absence of glucagon secretion after hypoglycemia is irreversible. This is a scenario specific to hypoglycemia, since other stimuli, including administration of amino acids, insulin withdrawal, lipopolysaccharide exposure and exercise lead to substantial glucagon responses though attenuated compared to nondiabetic individuals in head-to-head studies. The derailed glucagon secretion is not confined to hypoglycemia as individuals with type 1 diabetes, as opposed to nondiabetic individuals display glucagon hypersecretion after meals, thereby potentially contributing to insulin resistance. The complexity of these phenomena may relate to activation of distinct regulatory pathways controlling glucagon secretion i.e., intra-islet paracrine signaling, direct and autonomic nervous signaling.
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Affiliation(s)
- Mads Bisgaard Bengtsen
- Department of Endocrinology and Internal MedicineAarhus University HospitalAarhusDenmark
- Department of Internal MedicineRegional Hospital HorsensHorsensDenmark
| | - Niels Møller
- Department of Endocrinology and Internal MedicineAarhus University HospitalAarhusDenmark
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Ramzy A, Kieffer TJ. Altered islet prohormone processing: A cause or consequence of diabetes? Physiol Rev 2021; 102:155-208. [PMID: 34280055 DOI: 10.1152/physrev.00008.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peptide hormones are first produced as larger precursor prohormones that require endoproteolytic cleavage to liberate the mature hormones. A structurally conserved but functionally distinct family of nine prohormone convertase enzymes (PCs) are responsible for cleavage of protein precursors of which PC1/3 and PC2 are known to be exclusive to neuroendocrine cells and responsible for prohormone cleavage. Differential expression of PCs within tissues define prohormone processing; whereas glucagon is the major product liberated from proglucagon via PC2 in pancreatic α-cells, proglucagon is preferentially processed by PC1/3 in intestinal L cells to produce glucagon-like peptides 1 and 2 (GLP-1, GLP-2). Beyond our understanding of processing of islet prohormones in healthy islets, there is convincing evidence that proinsulin, proIAPP, and proglucagon processing is altered during prediabetes and diabetes. There is predictive value of elevated circulating proinsulin or proinsulin : C-peptide ratio for progression to type 2 diabetes and elevated proinsulin or proinsulin : C-peptide is predictive for development of type 1 diabetes in at risk groups. After onset of diabetes, patients have elevated circulating proinsulin and proIAPP and proinsulin may be an autoantigen in type 1 diabetes. Further, preclinical studies reveal that α-cells have altered proglucagon processing during diabetes leading to increased GLP-1 production. We conclude that despite strong associative data, current evidence is inconclusive on the potential causal role of impaired prohormone processing in diabetes, and suggest that future work should focus on resolving the question of whether altered prohormone processing is a causal driver or merely a consequence of diabetes pathology.
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Affiliation(s)
- Adam Ramzy
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
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Kraft G, Coate KC, Smith M, Farmer B, Scott M, Cherrington AD, Edgerton DS. The Importance of the Mechanisms by Which Insulin Regulates Meal-Associated Liver Glucose Uptake in the Dog. Diabetes 2021; 70:1292-1302. [PMID: 33757993 PMCID: PMC8275892 DOI: 10.2337/db20-1271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/18/2021] [Indexed: 12/17/2022]
Abstract
Hepatic glucose uptake (HGU) is critical for maintaining normal postprandial glucose metabolism. Insulin is clearly a key regulator of HGU, but the physiologic mechanisms by which it acts have yet to be established. This study sought to determine the mechanisms by which insulin regulates liver glucose uptake under postprandial-like conditions (hyperinsulinemia, hyperglycemia, and a positive portal vein-to-arterial glucose gradient). Portal vein insulin infusion increased hepatic insulin levels fivefold in healthy dogs. In one group (n = 7), the physiologic response was allowed to fully occur, while in another (n = 7), insulin's indirect hepatic effects, occurring secondary to its actions on adipose tissue, pancreas, and brain, were blocked. This was accomplished by infusing triglyceride (intravenous), glucagon (portal vein), and inhibitors of brain insulin action (intracerebroventricular) to prevent decreases in plasma free fatty acids or glucagon, while blocking increased hypothalamic insulin signaling for 4 h. In contrast to the indirect hepatic effects of insulin, which were previously shown capable of independently generating a half-maximal stimulation of HGU, direct hepatic insulin action was by itself able to fully stimulate HGU. This suggests that under hyperinsulinemic/hyperglycemic conditions insulin's indirect effects are redundant to direct engagement of hepatocyte insulin receptors.
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Affiliation(s)
- Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Katie C Coate
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Marta Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Melanie Scott
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
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Mechanism of insulin resistance in obesity: a role of ATP. Front Med 2021; 15:372-382. [PMID: 34047935 DOI: 10.1007/s11684-021-0862-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 04/25/2021] [Indexed: 12/12/2022]
Abstract
Obesity increases the risk of type 2 diabetes through the induction of insulin resistance. The mechanism of insulin resistance has been extensively investigated for more than 60 years, but the essential pathogenic signal remains missing. Existing hypotheses include inflammation, mitochondrial dysfunction, hyperinsulinemia, hyperglucagonemia, glucotoxicity, and lipotoxicity. Drug discoveries based on these hypotheses are unsuccessful in the development of new medicines. In this review, multidisciplinary literature is integrated to evaluate ATP as a primary signal for insulin resistance. The ATP production is elevated in insulin-sensitive cells under obese conditions independent of energy demand, which we have named "mitochondrial overheating." Overheating occurs because of substrate oversupply to mitochondria, leading to extra ATP production. The ATP overproduction contributes to the systemic insulin resistance through several mechanisms, such as inhibition of AMPK, induction of mTOR, hyperinsulinemia, hyperglucagonemia, and mitochondrial dysfunction. Insulin resistance represents a feedback regulation of energy oversupply in cells to control mitochondrial overloading by substrates. Insulin resistance cuts down the substrate uptake to attenuate mitochondrial overloading. The downregulation of the mitochondrial overloading by medicines, bypass surgeries, calorie restriction, and physical exercise leads to insulin sensitization in patients. Therefore, ATP may represent the primary signal of insulin resistance in the cellular protective response to the substrate oversupply. The prevention of ATP overproduction represents a key strategy for insulin sensitization.
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Glucagon transiently stimulates mTORC1 by activation of an EPAC/Rap1 signaling axis. Cell Signal 2021; 84:110010. [PMID: 33872697 PMCID: PMC8169602 DOI: 10.1016/j.cellsig.2021.110010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/22/2022]
Abstract
Activation of the protein kinase mechanistic target of rapamycin (mTOR) in both complexes 1 and 2 (mTORC1/2) in the liver is repressed during fasting and rapidly stimulated in response to a meal. The effect of feeding on hepatic mTORC1/2 is attributed to an increase in plasma levels of nutrients, such as amino acids, and insulin. By contrast, fasting is associated with elevated plasma levels of glucagon, which is conventionally viewed as having a counter-regulatory role to insulin. More recently an expanded role for glucagon action in post-prandial metabolism has been demonstrated. Herein we investigated the impact of insulin and glucagon on mTORC1/2 activation. In H4IIE and HepG2 cultures, insulin enhanced phosphorylation of the mTORC1 substrates S6K1 and 4E-BP1. Surprisingly, the effect of glucagon on mTORC1 was biphasic, wherein there was an acute increase in phosphorylation of S6K1 and 4E-BP1 over the first hour of exposure, followed by latent suppression. The transient stimulatory effect of glucagon on mTORC1 was not additive with insulin, suggesting convergent signaling. Glucagon enhanced cAMP levels and mTORC1 stimulation required activation of the glucagon receptor, PI3K/Akt, and exchange protein activated by cAMP (EPAC). EPAC acts as the guanine nucleotide exchange factor for the small GTPase Rap1. Rap1 expression enhanced S6K1 phosphorylation and glucagon addition to culture medium promoted Rap1-GTP loading. Signaling through mTORC1 acts to regulate protein synthesis and we found that glucagon promoted an EPAC-dependent increase in protein synthesis. Overall, the findings support that glucagon elicits acute activation of mTORC1/2 by an EPAC-dependent increase in Rap1-GTP.
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