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Kang Q, Jia J, Dean ED, Yuan H, Dai C, Li Z, Jiang F, Zhang XK, Powers AC, Chen W, Li M. ErbB3 is required for hyperaminoacidemia-induced pancreatic α cell hyperplasia. J Biol Chem 2024; 300:107499. [PMID: 38944125 PMCID: PMC11326907 DOI: 10.1016/j.jbc.2024.107499] [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: 03/14/2024] [Revised: 05/18/2024] [Accepted: 06/02/2024] [Indexed: 07/01/2024] Open
Abstract
Blood amino acid levels are maintained in a narrow physiological range. The pancreatic α cells have emerged as the primary aminoacidemia regulator through glucagon secretion to promote hepatic amino acid catabolism. Interruption of glucagon signaling disrupts the liver-α cells axis leading to hyperaminoacidemia, which triggers a compensatory rise in glucagon secretion and α cell hyperplasia. The mechanisms of hyperaminoacidemia-induced α cell hyperplasia remain incompletely understood. Using a mouse α cell line and in vivo studies in zebrafish and mice, we found that hyperaminoacidemia-induced α cell hyperplasia requires ErbB3 signaling. In addition to mechanistic target of rapamycin complex 1, another ErbB3 downstream effector signal transducer and activator of transcription 3 also plays a role in α cell hyperplasia. Mechanistically, ErbB3 may partner with ErbB2 to stimulate cyclin D2 and suppress p27 via mechanistic target of rapamycin complex 1 and signal transducer and activator of transcription 3. Our study identifies ErbB3 as a new regulator for hyperaminoacidemia-induced α cell proliferation and a critical component of the liver-α cells axis that regulates aminoacidemia.
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Affiliation(s)
- Qi Kang
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Jianxin Jia
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - E Danielle Dean
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hang Yuan
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Chunhua Dai
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Zhehui Li
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Fuquan Jiang
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Xiao-Kun Zhang
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Alvin C Powers
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; VA Tennessee Valley Healthcare System, Nashville, Tennessee, USA
| | - Wenbiao Chen
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
| | - Mingyu Li
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China; State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory, Xiamen University, Xiamen, China.
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2
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Hill TG, Hill DJ. The Importance of Intra-Islet Communication in the Function and Plasticity of the Islets of Langerhans during Health and Diabetes. Int J Mol Sci 2024; 25:4070. [PMID: 38612880 PMCID: PMC11012451 DOI: 10.3390/ijms25074070] [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: 02/27/2024] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes.
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Affiliation(s)
- Thomas G. Hill
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - David J. Hill
- Lawson Health Research Institute, St. Joseph’s Health Care, London, ON N6A 4V2, Canada;
- Departments of Medicine, Physiology and Pharmacology, Western University, London, ON N6A 3K7, Canada
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3
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Estes SK, Shiota C, O'Brien TP, Printz RL, Shiota M. The impact of glucagon to support postabsorptive glucose flux and glycemia in healthy rats and its attenuation in male Zucker diabetic fatty rats. Am J Physiol Endocrinol Metab 2024; 326:E308-E325. [PMID: 38265288 PMCID: PMC11193518 DOI: 10.1152/ajpendo.00192.2023] [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: 06/26/2023] [Revised: 01/19/2024] [Accepted: 01/19/2024] [Indexed: 01/25/2024]
Abstract
Hyperglucagonemia is a hallmark of type 2 diabetes (T2DM), yet the role of elevated plasma glucagon (P-GCG) to promote excessive postabsorptive glucose production and contribute to hyperglycemia in patients with this disease remains debatable. We investigated the acute action of P-GCG to safeguard/support postabsorptive endogenous glucose production (EGP) and euglycemia in healthy Zucker control lean (ZCL) rats. Using male Zucker diabetic fatty (ZDF) rats that exhibit the typical metabolic disorders of human T2DM, such as excessive EGP, hyperglycemia, hyperinsulinemia, and hyperglucagonemia, we examined the ability of hyperglucagonemia to promote greater rates of postabsorptive EGP and hyperglycemia. Euglycemic or hyperglycemic basal insulin (INS-BC) and glucagon (GCG-BC) clamps were performed in the absence or during an acute setting of glucagon deficiency (GCG-DF, ∼10% of basal), either alone or in combination with insulin deficiency (INS-DF, ∼10% of basal). Glucose appearance, disappearance, and cycling rates were measured using [2-3H] and [3-3H]-glucose. In ZCL rats, GCG-DF reduced the levels of hepatic cyclic AMP, EGP, and plasma glucose (PG) by 50%, 32%, and 50%, respectively. EGP fell in the presence GCG-DF and INS-BC, but under GCG-DF and INS-DF, EGP and PG increased two- and threefold, respectively. GCG-DF revealed the hyperglucagonemia present in ZDF rats lacked the ability to regulate hepatic intracellular cyclic AMP levels and glucose flux, since EGP and PG levels fell by only 10%. We conclude that the liver in T2DM suffers from resistance to all three major regulatory factors, glucagon, insulin, and glucose, thus leading to a loss of metabolic flexibility.NEW & NOTEWORTHY In postabsorptive state, basal plasma insulin (P-INS) and plasma glucose (PG) act dominantly to increase hepatic glucose cycling and reduce endogenous glucose production (EGP) and PG in healthy rats, which is only counteracted by the acute action of basal plasma glucagon (P-GCG) to support EGP and euglycemia. Hyperglucagonemia, a hallmark of type 2 diabetes (T2DM) present in Zucker diabetic fatty (ZDF) rats, is not the primary mediator of hyperglycemia and high EGP as commonly thought; instead, the liver is resistant to glucagon as well as insulin and glucose.
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Affiliation(s)
- Shanea K Estes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Chiyo Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Tracy P O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Richard L Printz
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
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4
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Varney MJ, Benovic JL. The Role of G Protein-Coupled Receptors and Receptor Kinases in Pancreatic β-Cell Function and Diabetes. Pharmacol Rev 2024; 76:267-299. [PMID: 38351071 PMCID: PMC10877731 DOI: 10.1124/pharmrev.123.001015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/01/2023] [Accepted: 12/07/2023] [Indexed: 02/16/2024] Open
Abstract
Type 2 diabetes (T2D) mellitus has emerged as a major global health concern that has accelerated in recent years due to poor diet and lifestyle. Afflicted individuals have high blood glucose levels that stem from the inability of the pancreas to make enough insulin to meet demand. Although medication can help to maintain normal blood glucose levels in individuals with chronic disease, many of these medicines are outdated, have severe side effects, and often become less efficacious over time, necessitating the need for insulin therapy. G protein-coupled receptors (GPCRs) regulate many physiologic processes, including blood glucose levels. In pancreatic β cells, GPCRs regulate β-cell growth, apoptosis, and insulin secretion, which are all critical in maintaining sufficient β-cell mass and insulin output to ensure euglycemia. In recent years, new insights into the signaling of incretin receptors and other GPCRs have underscored the potential of these receptors as desirable targets in the treatment of diabetes. The signaling of these receptors is modulated by GPCR kinases (GRKs) that phosphorylate agonist-activated GPCRs, marking the receptor for arrestin binding and internalization. Interestingly, genome-wide association studies using diabetic patient cohorts link the GRKs and arrestins with T2D. Moreover, recent reports show that GRKs and arrestins expressed in the β cell serve a critical role in the regulation of β-cell function, including β-cell growth and insulin secretion in both GPCR-dependent and -independent pathways. In this review, we describe recent insights into GPCR signaling and the importance of GRK function in modulating β-cell physiology. SIGNIFICANCE STATEMENT: Pancreatic β cells contain a diverse array of G protein-coupled receptors (GPCRs) that have been shown to improve β-cell function and survival, yet only a handful have been successfully targeted in the treatment of diabetes. This review discusses recent advances in our understanding of β-cell GPCR pharmacology and regulation by GPCR kinases while also highlighting the necessity of investigating islet-enriched GPCRs that have largely been unexplored to unveil novel treatment strategies.
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Affiliation(s)
- Matthew J Varney
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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5
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Yuan H, Kang Q, Li Z, Bai X, Jia J, Han D, Wu X, Li M. Crispr-Cas9 mediated complete deletion of glucagon receptor in mice display hyperglucagonemia and α-cell hyperplasia. Biochem Biophys Res Commun 2023; 643:121-128. [PMID: 36596263 DOI: 10.1016/j.bbrc.2022.12.079] [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: 12/12/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022]
Abstract
Glucagon receptor plays an important role in the regulation of glucose metabolism. Studies have revealed that glucagon receptor antagonism is a potential effective treatment for diabetes. However, the functions of GCGR have not been fully illustrated. Although two Gcgr truncation knockout mice models have been widely used for GCGR function studies, truncated gene may remain neomorphic and/or dominant-negative function. In this study, we took the advantages of Crispr-Cas9 technique and generated a novel allele of GCGR in the mouse that yields complete loss of GCGR protein. Our studies reveal that complete deletion of Gcgr results in hyperglucagonemia, α-cell hyperplasia, improvement of glucose tolerance. These results are similar to the Gcgr-truncated mutation in mice. Hence, we provide a novel strain of GCGR knockout mice for the GCGR function studies.
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Affiliation(s)
- Hang Yuan
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China; Department of Cardiac Surgery, The Xiamen Cardiovascular Hospital of Xiamen University, Xiamen, 361016, China
| | - Qi Kang
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, 361102, China
| | - Zhehui Li
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China
| | - Xuanxuan Bai
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China; School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jianxin Jia
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, 361102, China
| | - Daxiong Han
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China
| | - Xijie Wu
- Department of Cardiac Surgery, The Xiamen Cardiovascular Hospital of Xiamen University, Xiamen, 361016, China.
| | - Mingyu Li
- Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, 361102, China; Key Laboratory of Tropical Marine Ecosystem and Bioresource, Fourth Institute of Oceanography, Ministry of Natural Resources, Beihai, 536007, China.
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6
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Winther-Sørensen M, Holst JJ, Wewer Albrechtsen NJ. The feedback cycles between glucose, amino acids and lipids and alpha cell secretion and their role in metabolic fatty liver disease. Curr Opin Lipidol 2023; 34:27-31. [PMID: 36373738 DOI: 10.1097/mol.0000000000000857] [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] [Indexed: 11/16/2022]
Abstract
PURPOSE OF REVIEW Glucagon increases hepatic glucose production and in patients with metabolic diseases, glucagon secretion is increased contributing to diabetic hyperglycemia. This review explores the role of amino acids and lipids in the regulation of glucagon secretion and how it may be disturbed in metabolic diseases such as obesity and metabolic associated fatty liver disease (MAFLD). RECENT FINDINGS Human and animal studies have shown that MAFLD is associated with glucagon resistance towards amino acid catabolism, resulting in elevated plasma levels of amino acids. A recent clinical study showed that MAFLD is also associated with glucagon resistance towards lipid metabolism. In contrast, MAFLD may not decrease hepatic sensitivity to the stimulatory effects of glucagon on glucose production. SUMMARY Elevated plasma levels of amino acids and lipids associated with MAFLD may cause diabetogenic hyperglucagonemia. MAFLD and glucagon resistance may therefore be causally linked to hyperglycemia and the development of type 2 diabetes.
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Affiliation(s)
- Marie Winther-Sørensen
- Department of Biomedical Sciences
- NNF Center for Protein Research, Faculty of Health and Medical Sciences
| | | | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences
- NNF Center for Protein Research, Faculty of Health and Medical Sciences
- Department for Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
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7
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Rodgers RL. A reappraisal of the role of cyclic AMP in the physiological action of glucagon. Peptides 2023; 159:170906. [PMID: 36396082 DOI: 10.1016/j.peptides.2022.170906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/11/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022]
Abstract
Effects of the metabolic hormone glucagon can be physiological or supraphysiological, based on agonist concentration and the mediating cellular signal. The threshold concentration (TC) for activating the AC/cAMP signal pathway in liver is ≥ 100 pM. By contrast, mean plasma concentrations are around 20-45 pM, depending on the vascular bed. Accordingly, effects produced at TCs below 100 pM are physiological and mediated by cellular signal pathways other than AC/cAMP. Effects generated at concentrations above 100 pM are supraphysiological, often mediated by simultaneous activation of cAMP-independent and -dependent pathways. Physiological responses, and their established or implicated signal pathways, include stimulation of: glucose mobilization, fatty acid oxidation, and urea synthesis in liver (PLC/IP3/Ca2+/CaM); lipolysis in white and brown adipose tissue and oxygen consumption in brown adipose of the rat but not in humans (PLC/IP3/Ca2+/CaM); renal potassium and phosphate excretion in rodents and GFR in humans (signal undetermined); and glucose utilization in rat heart (PI3K/akt). Supraphysiological responses involve the AC/cAMP pathway and include: enhanced stimulation of glucose mobilization and stimulation of urea synthesis in liver; further stimulation of white and brown adipose lipolysis and thermogenesis in brown adipose tissue; stimulation of renal Cl- transport; and increased rat heart contractility. The AC/cAMP pathway is likely recruited when plasma glucagon rises above 100 pM during periods of elevated metabolic stress and systemic glucose demand, such as in the early neonate or strenuously exercising adult. The current cAMP-centered model should therefore be reconsidered and replaced with one that places more emphasis on cAMP-independent pathways.
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Affiliation(s)
- Robert L Rodgers
- Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02935, USA.
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Gaspar TB, Lopes JM, Soares P, Vinagre J. An update on genetically engineered mouse models of pancreatic neuroendocrine neoplasms. Endocr Relat Cancer 2022; 29:R191-R208. [PMID: 36197786 DOI: 10.1530/erc-22-0166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/29/2022] [Indexed: 11/09/2022]
Abstract
Pancreatic neuroendocrine neoplasms (PanNENs) are rare and clinically challenging entities. At the molecular level, PanNENs' genetic profile is well characterized, but there is limited knowledge regarding the contribution of the newly identified genes to tumor initiation and progression. Genetically engineered mouse models (GEMMs) are the most versatile tool for studying the plethora of genetic variations influencing PanNENs' etiopathogenesis and behavior over time. In this review, we present the state of the art of the most relevant PanNEN GEMMs available and correlate their findings with the human neoplasms' counterparts. We discuss the historic GEMMs as the most used and with higher translational utility models. GEMMs with Men1 and glucagon receptor gene germline alterations stand out as the most faithful models in recapitulating human disease; RIP-Tag models are unique models of early-onset, highly vascularized, invasive carcinomas. We also include a section of the most recent GEMMs that evaluate pathways related to cell cycle and apoptosis, Pi3k/Akt/mTOR, and Atrx/Daxx. For the latter, their tumorigenic effect is heterogeneous. In particular, for Atrx/Daxx, we will require more in-depth studies to evaluate their contribution; even though they are prevalent genetic events in PanNENs, they have low/inexistent tumorigenic capacity per se in GEMMs. Researchers planning to use GEMMs can find a road map of the main clinical features in this review, presented as a guide that summarizes the chief milestones achieved. We identify pitfalls to overcome, concerning the novel designs and standardization of results, so that future models can replicate human disease more closely.
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Affiliation(s)
- Tiago Bordeira Gaspar
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Ipatimup - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
- ICBAS - Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
- FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - José Manuel Lopes
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Ipatimup - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
- FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
- Department of Pathology, Centro Hospitalar e Universitário de São João, Porto, Portugal
| | - Paula Soares
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Ipatimup - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
- FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - João Vinagre
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Ipatimup - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
- FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
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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: 31] [Impact Index Per Article: 15.5] [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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10
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Insights into the Role of Glucagon Receptor Signaling in Metabolic Regulation from Pharmacological Inhibition and Tissue-Specific Knockout Models. Biomedicines 2022; 10:biomedicines10081907. [PMID: 36009454 PMCID: PMC9405517 DOI: 10.3390/biomedicines10081907] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
While glucagon has long been recognized as the primary counter hormone to insulin’s actions, it has recently gained recognition as a metabolic regulator with its effects extending beyond control of glycemia. Recently developed models of tissue-specific glucagon receptor knockouts have advanced our understanding of this hormone, providing novel insight into the role it plays within organs as well as its systemic effects. Studies where the pharmacological blockade of the glucagon receptor has been employed have proved similarly valuable in the study of organ-specific and systemic roles of glucagon signaling. Studies carried out employing these tools demonstrate that glucagon indeed plays a role in regulating glycemia, but also in amino acid and lipid metabolism, systemic endocrine, and paracrine function, and in the response to cardiovascular injury. Here, we briefly review recent progress in our understanding of glucagon’s role made through inhibition of glucagon receptor signaling utilizing glucagon receptor antagonists and tissue specific genetic knockout models.
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11
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Glucagon-receptor-antagonism-mediated β-cell regeneration as an effective anti-diabetic therapy. Cell Rep 2022; 39:110872. [PMID: 35649369 DOI: 10.1016/j.celrep.2022.110872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 02/12/2022] [Accepted: 05/04/2022] [Indexed: 01/10/2023] Open
Abstract
Type 1 diabetes mellitus (T1D) is a chronic disease with potentially severe complications, and β-cell deficiency underlies this disease. Despite active research, no therapy to date has been able to induce β-cell regeneration in humans. Here, we discover the β-cell regenerative effects of glucagon receptor antibody (anti-GcgR). Treatment with anti-GcgR in mouse models of β-cell deficiency leads to reversal of hyperglycemia, increase in plasma insulin levels, and restoration of β-cell mass. We demonstrate that both β-cell proliferation and α- to β-cell transdifferentiation contribute to anti-GcgR-induced β-cell regeneration. Interestingly, anti-GcgR-induced α-cell hyperplasia can be uncoupled from β-cell regeneration after antibody clearance from the body. Importantly, we are able to show that anti-GcgR-induced β-cell regeneration is also observed in non-human primates. Furthermore, anti-GcgR and anti-CD3 combination therapy reverses diabetes and increases β-cell mass in a mouse model of autoimmune diabetes.
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12
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Rodgers RL. Glucagon, cyclic AMP, and hepatic glucose mobilization: A half‐century of uncertainty. Physiol Rep 2022; 10:e15263. [PMID: 35569125 PMCID: PMC9107925 DOI: 10.14814/phy2.15263] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 12/14/2022] Open
Abstract
For at least 50 years, the prevailing view has been that the adenylate cyclase (AC)/cyclic AMP (cAMP)/protein kinase A pathway is the predominant signal mediating the hepatic glucose‐mobilizing actions of glucagon. A wealth of evidence, however, supports the alternative, that the operative signal most of the time is the phospholipase C (PLC)/inositol‐phosphate (IP3)/calcium/calmodulin pathway. The evidence can be summarized as follows: (1) The consensus threshold glucagon concentration for activating AC ex vivo is 100 pM, but the statistical hepatic portal plasma glucagon concentration range, measured by RIA, is between 28 and 60 pM; (2) Within that physiological concentration range, glucagon stimulates the PLC/IP3 pathway and robustly increases glucose output without affecting the AC/cAMP pathway; (3) Activation of a latent, amplified AC/cAMP pathway at concentrations below 60 pM is very unlikely; and (4) Activation of the PLC/IP3 pathway at physiological concentrations produces intracellular effects that are similar to those produced by activation of the AC/cAMP pathway at concentrations above 100 pM, including elevated intracellular calcium and altered activities and expressions of key enzymes involved in glycogenolysis, gluconeogenesis, and glycogen synthesis. Under metabolically stressful conditions, as in the early neonate or exercising adult, plasma glucagon concentrations often exceed 100 pM, recruiting the AC/cAMP pathway and enhancing the activation of PLC/IP3 pathway to boost glucose output, adaptively meeting the elevated systemic glucose demand. Whether the AC/cAMP pathway is consistently activated in starvation or diabetes is not clear. Because the importance of glucagon in the pathogenesis of diabetes is becoming increasingly evident, it is even more urgent now to resolve lingering uncertainties and definitively establish glucagon’s true mechanism of glycemia regulation in health and disease.
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Affiliation(s)
- Robert L. Rodgers
- Department of Biomedical and Pharmaceutical Sciences College of Pharmacy University of Rhode Island Kingston Rhode Island USA
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13
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Therapeutic RNA-silencing oligonucleotides in metabolic diseases. Nat Rev Drug Discov 2022; 21:417-439. [PMID: 35210608 DOI: 10.1038/s41573-022-00407-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2022] [Indexed: 12/14/2022]
Abstract
Recent years have seen unprecedented activity in the development of RNA-silencing oligonucleotide therapeutics for metabolic diseases. Improved oligonucleotide design and optimization of synthetic nucleic acid chemistry, in combination with the development of highly selective and efficient conjugate delivery technology platforms, have established and validated oligonucleotides as a new class of drugs. To date, there are five marketed oligonucleotide therapies, with many more in clinical studies, for both rare and common liver-driven metabolic diseases. Here, we provide an overview of recent developments in the field of oligonucleotide therapeutics in metabolism, review past and current clinical trials, and discuss ongoing challenges and possible future developments.
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14
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Conceição-Furber E, Coskun T, Sloop KW, Samms RJ. Is Glucagon Receptor Activation the Thermogenic Solution for Treating Obesity? Front Endocrinol (Lausanne) 2022; 13:868037. [PMID: 35547006 PMCID: PMC9081793 DOI: 10.3389/fendo.2022.868037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/07/2022] [Indexed: 12/19/2022] Open
Abstract
A major challenge of obesity therapy is to sustain clinically relevant weight loss over time. Achieving this goal likely requires both reducing daily caloric intake and increasing caloric expenditure. Over the past decade, advances in pharmaceutical engineering of ligands targeting G protein-coupled receptors have led to the development of highly effective anorectic agents. These include mono-agonists of the GLP-1R and dual GIPR/GLP-1R co-agonists that have demonstrated substantial weight loss in experimental models and in humans. By contrast, currently, there are no medicines available that effectively augment metabolic rate to promote weight loss. Here, we present evidence indicating that activation of the GCGR may provide a solution to this unmet therapeutic need. In adult humans, GCGR agonism increases energy expenditure to a magnitude sufficient for inducing a negative energy balance. In preclinical studies, the glucagon-GCGR system affects key metabolically relevant organs (including the liver and white and brown adipose tissue) to boost whole-body thermogenic capacity and protect from obesity. Further, activation of the GCGR has been shown to augment both the magnitude and duration of weight loss that is achieved by either selective GLP-1R or dual GIPR/GLP-1R agonism in rodents. Based on the accumulation of such findings, we propose that the thermogenic activity of GCGR agonism will also complement other anti-obesity agents that lower body weight by suppressing appetite.
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15
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Rhyu J, Yu R. Newly discovered endocrine functions of the liver. World J Hepatol 2021; 13:1611-1628. [PMID: 34904032 PMCID: PMC8637678 DOI: 10.4254/wjh.v13.i11.1611] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/05/2021] [Accepted: 09/23/2021] [Indexed: 02/06/2023] Open
Abstract
The liver, the largest solid visceral organ of the body, has numerous endocrine functions, such as direct hormone and hepatokine production, hormone metabolism, synthesis of binding proteins, and processing and redistribution of metabolic fuels. In the last 10 years, many new endocrine functions of the liver have been discovered. Advances in the classical endocrine functions include delineation of mechanisms of liver production of endocrine hormones [including 25-hydroxyvitamin D, insulin-like growth factor 1 (IGF-1), and angiotensinogen], hepatic metabolism of hormones (including thyroid hormones, glucagon-like peptide-1, and steroid hormones), and actions of specific binding proteins to glucocorticoids, sex steroids, and thyroid hormones. These studies have furthered insight into cirrhosis-associated endocrinopathies, such as hypogonadism, osteoporosis, IGF-1 deficiency, vitamin D deficiency, alterations in glucose and lipid homeostasis, and controversially relative adrenal insufficiency. Several novel endocrine functions of the liver have also been unraveled, elucidating the liver’s key negative feedback regulatory role in the pancreatic α cell-liver axis, which regulates pancreatic α cell mass, glucagon secretion, and circulating amino acid levels. Betatrophin and other hepatokines, such as fetuin-A and fibroblast growth factor 21, have also been discovered to play important endocrine roles in modulating insulin sensitivity, lipid metabolism, and body weight. It is expected that more endocrine functions of the liver will be revealed in the near future.
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Affiliation(s)
- Jane Rhyu
- Division of Endocrinology, Diabetes, and Metabolism, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, United States
| | - Run Yu
- Division of Endocrinology, Diabetes, and Metabolism, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, United States
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16
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Demir S, Nawroth PP, Herzig S, Ekim Üstünel B. Emerging Targets in Type 2 Diabetes and Diabetic Complications. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100275. [PMID: 34319011 PMCID: PMC8456215 DOI: 10.1002/advs.202100275] [Citation(s) in RCA: 132] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/07/2021] [Indexed: 05/06/2023]
Abstract
Type 2 diabetes is a metabolic, chronic disorder characterized by insulin resistance and elevated blood glucose levels. Although a large drug portfolio exists to keep the blood glucose levels under control, these medications are not without side effects. More importantly, once diagnosed diabetes is rarely reversible. Dysfunctions in the kidney, retina, cardiovascular system, neurons, and liver represent the common complications of diabetes, which again lack effective therapies that can reverse organ injury. Overall, the molecular mechanisms of how type 2 diabetes develops and leads to irreparable organ damage remain elusive. This review particularly focuses on novel targets that may play role in pathogenesis of type 2 diabetes. Further research on these targets may eventually pave the way to novel therapies for the treatment-or even the prevention-of type 2 diabetes along with its complications.
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Affiliation(s)
- Sevgican Demir
- Institute for Diabetes and Cancer (IDC)Helmholtz Center MunichIngolstädter Landstr. 1Neuherberg85764Germany
- Joint Heidelberg ‐ IDC Translational Diabetes ProgramInternal Medicine 1Heidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
- DZDDeutsches Zentrum für DiabetesforschungIngolstädter Landstraße 1Neuherberg85764Germany
- Department of Internal Medicine 1 and Clinical ChemistryHeidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
| | - Peter P. Nawroth
- Institute for Diabetes and Cancer (IDC)Helmholtz Center MunichIngolstädter Landstr. 1Neuherberg85764Germany
- Joint Heidelberg ‐ IDC Translational Diabetes ProgramInternal Medicine 1Heidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
- DZDDeutsches Zentrum für DiabetesforschungIngolstädter Landstraße 1Neuherberg85764Germany
- Department of Internal Medicine 1 and Clinical ChemistryHeidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
| | - Stephan Herzig
- Institute for Diabetes and Cancer (IDC)Helmholtz Center MunichIngolstädter Landstr. 1Neuherberg85764Germany
- Joint Heidelberg ‐ IDC Translational Diabetes ProgramInternal Medicine 1Heidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
- DZDDeutsches Zentrum für DiabetesforschungIngolstädter Landstraße 1Neuherberg85764Germany
- Department of Internal Medicine 1 and Clinical ChemistryHeidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
| | - Bilgen Ekim Üstünel
- Institute for Diabetes and Cancer (IDC)Helmholtz Center MunichIngolstädter Landstr. 1Neuherberg85764Germany
- Joint Heidelberg ‐ IDC Translational Diabetes ProgramInternal Medicine 1Heidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
- DZDDeutsches Zentrum für DiabetesforschungIngolstädter Landstraße 1Neuherberg85764Germany
- Department of Internal Medicine 1 and Clinical ChemistryHeidelberg University HospitalIm Neuenheimer Feld 410Heidelberg69120Germany
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17
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Lee YS, Song GJ, Jun HS. Betacellulin-Induced α-Cell Proliferation Is Mediated by ErbB3 and ErbB4, and May Contribute to β-Cell Regeneration. Front Cell Dev Biol 2021; 8:605110. [PMID: 33553143 PMCID: PMC7859283 DOI: 10.3389/fcell.2020.605110] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 12/15/2020] [Indexed: 11/15/2022] Open
Abstract
Betacellulin (BTC), an epidermal growth factor family, is known to promote β-cell regeneration. Recently, pancreatic α-cells have been highlighted as a source of new β-cells. We investigated the effect of BTC on α-cells. Insulin+glucagon+ double stained bihormonal cell levels and pancreatic and duodenal homeobox-1 expression were increased in mice treated with recombinant adenovirus-expressing BTC (rAd-BTC) and β-cell-ablated islet cells treated with BTC. In the islets of rAd-BTC-treated mice, both BrdU+glucagon+ and BrdU+insulin+ cell levels were significantly increased, with BrdU+glucagon+ cells showing the greater increase. Treatment of αTC1-9 cells with BTC significantly increased proliferation and cyclin D2 expression. BTC induced phosphorylation of ErbB receptors in αTC1-9 cells. The proliferative effect of BTC was mediated by ErbB-3 or ErbB-4 receptor kinase. BTC increased phosphorylation of ERK1/2, AKT, and mTOR and PC1/3 expression and GLP-1 production in α-cells, but BTC-induced proliferation was not changed by the GLP-1 receptor antagonist, exendin-9. We suggest that BTC has a direct role in α-cell proliferation via interaction with ErbB-3 and ErbB-4 receptors, and these increased α-cells might be a source of new β-cells.
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Affiliation(s)
- Young-Sun Lee
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea.,Department of Medical Science, College of Medicine, Catholic Kwandong University, Gangneung, South Korea.,Translational Brain Research Center, International St. Mary's Hospital, Catholic Kwandong University, Incheon, South Korea
| | - Gyun Jee Song
- Department of Medical Science, College of Medicine, Catholic Kwandong University, Gangneung, South Korea.,Translational Brain Research Center, International St. Mary's Hospital, Catholic Kwandong University, Incheon, South Korea
| | - Hee-Sook Jun
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea.,College of Pharmacy, Gachon University, Incheon, South Korea.,Gachon Medical and Convergence Institute, Gachon Gil Medical Center, Incheon, South Korea
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18
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Detjen K, Hammerich L, Özdirik B, Demir M, Wiedenmann B, Tacke F, Jann H, Roderburg C. Models of Gastroenteropancreatic Neuroendocrine Neoplasms: Current Status and Future Directions. Neuroendocrinology 2021; 111:217-236. [PMID: 32615560 DOI: 10.1159/000509864] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/23/2020] [Indexed: 11/19/2022]
Abstract
Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are a rare, heterogeneous group of tumors that originate from the endocrine system of the gastrointestinal tract and pancreas. GEP-NENs are subdivided according to their differentiation into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). Since GEP-NENs represent rare diseases, only limited data from large prospective, randomized clinical trials are available, and recommendations for treatment of GEP-NEN are in part based on data from retrospective analyses or case series. In this context, tractable disease models that reflect the situation in humans and that allow to recapitulate the different clinical aspects and disease stages of GEP-NET or GEP-NEC are urgently needed. In this review, we highlight available data on mouse models for GEP-NEN. We discuss how these models reflect tumor biology of human disease and whether these models could serve as a tool for understanding the pathogenesis of GEP-NEN and for disease modeling and pharmacosensitivity assays, facilitating prediction of treatment response in patients. In addition, open issues applicable for future developments will be discussed.
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Affiliation(s)
- Katharina Detjen
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Linda Hammerich
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Burcin Özdirik
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Münevver Demir
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Bertram Wiedenmann
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Frank Tacke
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Henning Jann
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany
| | - Christoph Roderburg
- Department of Hepatology and Gastroenterology, Charité - University Medicine Berlin, Campus Virchow Klinikum and Charité Campus Mitte, Berlin, Germany,
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19
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Hartig SM, Cox AR. Paracrine signaling in islet function and survival. J Mol Med (Berl) 2020; 98:451-467. [PMID: 32067063 DOI: 10.1007/s00109-020-01887-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/05/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a dense cellular network comprised of several cell types with endocrine function vital in the control of glucose homeostasis, metabolism, and feeding behavior. Within the islet, endocrine hormones also form an intricate paracrine network with supportive cells (endothelial, neuronal, immune) and secondary signaling molecules regulating cellular function and survival. Modulation of these signals has potential consequences for diabetes development, progression, and therapeutic intervention. Beta cell loss, reduced endogenous insulin secretion, and dysregulated glucagon secretion are hallmark features of both type 1 and 2 diabetes that not only impact systemic regulation of glucose, but also contribute to the function and survival of cells within the islet. Advancing research and technology have revealed new islet biology (cellular identity and transcriptomes) and identified previously unrecognized paracrine signals and mechanisms (somatostatin and ghrelin paracrine actions), while shifting prior views of intraislet communication. This review will summarize the paracrine signals regulating islet endocrine function and survival, the disruption and dysfunction that occur in diabetes, and potential therapeutic targets to preserve beta cell mass and function.
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Affiliation(s)
- Sean M Hartig
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Aaron R Cox
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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20
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Li E, Shan H, Chen L, Long A, Zhang Y, Liu Y, Jia L, Wei F, Han J, Li T, Liu X, Deng H, Wang Y. OLFR734 Mediates Glucose Metabolism as a Receptor of Asprosin. Cell Metab 2019; 30:319-328.e8. [PMID: 31230984 DOI: 10.1016/j.cmet.2019.05.022] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 01/09/2019] [Accepted: 05/23/2019] [Indexed: 02/08/2023]
Abstract
Asprosin is a fasting-induced hormone that promotes glucose production in the liver and stimulates appetite in the hypothalamus by activating the cAMP signaling pathway via an unknown G protein-coupled receptor (GPCR). However, the bona fide receptor of Asprosin is unclear. Here, we have identified that the olfactory receptor OLFR734 acts as a receptor of Asprosin to modulate hepatic glucose production. Olfr734 knockout mice show a blunted response to Asprosin, including attenuated cAMP levels and hepatic glucose production, and improved insulin sensitivity. As Olfr734 deficiency dramatically attenuates both fasting and high-fat-diet-induced glucose production, our results demonstrate a critical role of OLFR734 as a receptor of Asprosin to maintain glucose homeostasis during fasting and in obesity.
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Affiliation(s)
- Erwei Li
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Haili Shan
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Liqun Chen
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Aijun Long
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Yuanyuan Zhang
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Yang Liu
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Liangjie Jia
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Fangchao Wei
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jinbo Han
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Tong Li
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Xiaohui Liu
- National Protein Science Technology Center, Tsinghua University, 100084 Beijing, China
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Yiguo Wang
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China.
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21
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Rivero-Gutierrez B, Haller A, Holland J, Yates E, Khrisna R, Habegger K, Dimarchi R, D'Alessio D, Perez-Tilve D. Deletion of the glucagon receptor gene before and after experimental diabetes reveals differential protection from hyperglycemia. Mol Metab 2018; 17:28-38. [PMID: 30170980 PMCID: PMC6197675 DOI: 10.1016/j.molmet.2018.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE Mice with congenital loss of the glucagon receptor gene (Gcgr-/- mice) remain normoglycemic in insulinopenic conditions, suggesting that unopposed glucagon action is the driving force for hyperglycemia in Type-1 Diabetes Mellitus (T1DM). However, chronic loss of GCGR results in a neomorphic phenotype that includes hormonal signals with hypoglycemic activity. We combined temporally-controlled GCGR deletion with pharmacological treatments to dissect the direct contribution of GCGR signaling to glucose control in a common mouse model of T1DM. METHODS We induced experimental T1DM by injecting the beta-cell cytotoxin streptozotocin (STZ) in mice with congenital or temporally-controlled Gcgr loss-of-function using tamoxifen (TMX). RESULTS Disruption of Gcgr expression, using either an inducible approach in adult mice or animals with congenital knockout, abolished the response to a long-acting Gcgr agonist. Mice with either developmental Gcgr disruption or inducible deletion several weeks before STZ treatment maintained normoglycemia. However, mice with inducible knockout of the Gcgr one week after the onset of STZ diabetes had only partial correction of hyperglycemia, an effect that was reversed by GLP-1 receptor blockade. Mice with Gcgr deletion for either 2 or 6 weeks had similar patterns of gene expression, although the changes were generally larger with longer GCGR knockout. CONCLUSIONS These findings demonstrate that the effects of glucagon to mitigate diabetic hyperglycemia are not through acute signaling but require compensations that take weeks to develop.
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Affiliation(s)
- Belen Rivero-Gutierrez
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - April Haller
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - Jenna Holland
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - Emily Yates
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA
| | - Radha Khrisna
- Department of Medicine, Duke University School of Medicine, NC, USA
| | - Kirk Habegger
- Comprehensive Diabetes Center and Department of Medicine - Endocrinology, Diabetes & and Metabolism, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Richard Dimarchi
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - David D'Alessio
- Department of Medicine, Duke University School of Medicine, NC, USA
| | - Diego Perez-Tilve
- Department of Internal Medicine, University of Cincinnati, 2180 E. Galbraith Rd, Cincinnati, OH, USA.
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22
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Abstract
OBJECTIVE Endocrine tumor markers (ETMs) are important and indispensable tools in the diagnosis and follow-up of endocrine tumors. Unexpectedly high level of ETM (UHLETM) is often encountered in clinical practice. The objectives of this article are to discuss the approach to UHLETMs and describe the most common UHLETMs. METHODS Literature review and personal experience with UHLETMs. RESULTS A UHLETM is defined as an ETM level much higher than what an endocrinologist would expect based on the patient's clinical information, other biochemical test results, and imaging findings. Most UHLETMs are false positive, in that they do not indicate the existence or growth of an endocrine tumor. The key issue, however, is how to convincingly prove that a UHLETM is false positive. The most important question to help resolve UHLETMs is whether the UHLETMs are due to false or true results. Some UHLETMs are due to interpretation errors, laboratory errors, or spurious test results, while the true levels of the ETMs are normal or unchanged from previous results. Other UHLETMs are due to nontumor conditions or medications, and the true levels of the ETMs are indeed very high. When it is not straightforward to assess whether certain UHLETMs are due to false or true results, they may be due to novel conditions. CONCLUSION UHLETMs provide endocrinologists great opportunities to learn the basic biology and measurement of ETMs. Unresolved UHLETMs are exciting clinical research opportunities which may lead to discovery of new diseases and new mechanisms of measurement interference. ABBREVIATIONS 5-HIAAA = 5-hydroxyindoleacetic acid; 5-HTP = 5-hydroxytryptophan; CGA = chromogranin A; ETM = endocrine tumor marker; MTC = medullary thyroid carcinoma; UHLETM = unexpectedly high level of endocrine tumor marker.
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23
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Karanth S, Adams JD, Serrano MDLA, Quittner-Strom EB, Simcox J, Villanueva CJ, Ozcan L, Holland WL, Yost HJ, Vella A, Schlegel A. A Hepatocyte FOXN3-α Cell Glucagon Axis Regulates Fasting Glucose. Cell Rep 2018; 24:312-319. [PMID: 29996093 DOI: 10.1016/j.celrep.2018.06.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/07/2018] [Accepted: 06/08/2018] [Indexed: 01/26/2023] Open
Abstract
The common genetic variation at rs8004664 in the FOXN3 gene is independently and significantly associated with fasting blood glucose, but not insulin, in non-diabetic humans. Recently, we reported that primary hepatocytes from rs8004664 hyperglycemia risk allele carriers have increased FOXN3 transcript and protein levels and liver-limited overexpression of human FOXN3, a transcriptional repressor that had not been implicated in metabolic regulation previously, increases fasting blood glucose in zebrafish. Here, we find that injection of glucagon into mice and adult zebrafish decreases liver Foxn3 protein and transcript levels. Zebrafish foxn3 loss-of-function mutants have decreased fasting blood glucose, blood glucagon, liver gluconeogenic gene expression, and α cell mass. Conversely, liver-limited overexpression of foxn3 increases α cell mass. Supporting these genetic findings in model organisms, non-diabetic rs8004664 risk allele carriers have decreased suppression of glucagon during oral glucose tolerance testing. By reciprocally regulating each other, liver FOXN3 and glucagon control fasting glucose.
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Affiliation(s)
- Santhosh Karanth
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - J D Adams
- Department of Internal Medicine, Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Maria de Los Angeles Serrano
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Ezekiel B Quittner-Strom
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah College of Health, Salt Lake City, UT, USA
| | - Judith Simcox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Lale Ozcan
- Department of Medicine, Division of Molecular Medicine, Columbia University Medical Center, New York, NY, USA
| | - William L Holland
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah College of Health, Salt Lake City, UT, USA; Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - H Joseph Yost
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Adrian Vella
- Department of Internal Medicine, Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Amnon Schlegel
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah College of Health, Salt Lake City, UT, USA; Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
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MafB Is Critical for Glucagon Production and Secretion in Mouse Pancreatic α Cells In Vivo. Mol Cell Biol 2018; 38:MCB.00504-17. [PMID: 29378833 DOI: 10.1128/mcb.00504-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/19/2018] [Indexed: 12/14/2022] Open
Abstract
The MafB transcription factor is expressed in pancreatic α and β cells during development but becomes exclusive to α cells in adult rodents. Mafb-null (Mafb-/- ) mice were reported to have reduced α- and β-cell numbers throughout embryonic development. To further analyze the postnatal function of MafB in the pancreas, we generated endocrine cell-specific (MafbΔEndo ) and tamoxifen-dependent (MafbΔTAM ) Mafb knockout mice. MafbΔEndo mice exhibited reduced populations of insulin-positive (insulin+) and glucagon+ cells at postnatal day 0, but the insulin+ cell population recovered by 8 weeks of age. In contrast, the Arx+ glucagon+ cell fraction and glucagon expression remained decreased even in adulthood. MafbΔTAM mice, with Mafb deleted after pancreas maturation, also demonstrated diminished glucagon+ cells and glucagon content without affecting β cells. A decreased Arx+ glucagon+ cell population in MafbΔEndo mice was compensated for by an increased Arx+ pancreatic polypeptide+ cell population. Furthermore, gene expression analyses from both MafbΔEndo and MafbΔTAM islets revealed that MafB is a key regulator of glucagon expression in α cells. Finally, both mutants failed to respond to arginine, likely due to impaired arginine transporter gene expression and glucagon production ability. Taken together, our findings reveal that MafB is critical for the functional maintenance of mouse α cells in vivo, including glucagon production and secretion, as well as in development.
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Abstract
The lobules are the functional units of the liver. They consist of 15–25 layers of hepatocytes with specialized metabolic functions and gene expression patterns relative to their position along the lobule, a phenomenon referred to as metabolic zonation. The Wnt/β-catenin pathway regulates hepatocyte function but how the zonation is controlled to meet the metabolic demands of the liver is unclear. Glucagon regulates hepatic function. We now demonstrate that glucagon contributes to liver zonation by interacting and opposing the actions of the Wnt/β-catenin pathway. Liver zonation characterizes the separation of metabolic pathways along the lobules and is required for optimal function. Wnt/β-catenin signaling controls metabolic zonation by activating genes in the perivenous hepatocytes, while suppressing genes in the periportal counterparts. We now demonstrate that glucagon opposes the actions of Wnt/β-catenin signaling on gene expression and metabolic zonation pattern. The effects were more pronounced in the periportal hepatocytes where 28% of all genes were activated by glucagon and inhibited by Wnt/β-catenin. The glucagon and Wnt/β-catenin receptors and their signaling pathways are uniformly distributed in periportal and perivenous hepatocytes and the expression is not regulated by the opposing signal. Collectively, our results show that glucagon controls gene expression and metabolic zonation in the liver through a counterplay with the Wnt/β-catenin signaling pathway.
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26
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Hayashi Y, Seino Y. Regulation of amino acid metabolism and α-cell proliferation by glucagon. J Diabetes Investig 2018; 9:464-472. [PMID: 29314731 PMCID: PMC5934249 DOI: 10.1111/jdi.12797] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 12/25/2022] Open
Abstract
Both glucagon and glucagon-like peptide-1 (GLP-1) are produced from proglucagon through proteolytic cleavage. Blocking glucagon action increases the circulating levels of glucagon and GLP-1, reduces the blood glucose level, and induces the proliferation of islet α-cells. Glucagon blockade also suppresses hepatic amino acid catabolism and increases the serum amino acid level. In animal models defective in both glucagon and GLP-1, the blood glucose level is not reduced, indicating that GLP-1 is required for glucagon blockade to reduce the blood glucose level. In contrast, hyperplasia of α-cells and hyperaminoacidemia are observed in such animal models, indicating that GLP-1 is not required for the regulation of α-cell proliferation or amino acid metabolism. These findings suggest that the regulation of amino acid metabolism is a more important specific physiological role of glucagon than the regulation of glucose metabolism. Although the effects of glucagon deficiency on glucose metabolism are compensated by the suppression of insulin secretion, the effects on amino acid metabolism are not. Recently, data showing a feedback regulatory mechanism between the liver and islet α-cells, which is mediated by glucagon and amino acids, are accumulating. However, a number of questions on the mechanism of this regulation remain to be addressed. The profile of glucagon as a regulator of amino acid metabolism must be carefully considered for glucagon blockade to be applied therapeutically in the treatment of patients with diabetes.
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Affiliation(s)
- Yoshitaka Hayashi
- Division of Stress Adaptation and ProtectionResearch Institute of Environmental MedicineNagoyaJapan
| | - Yusuke Seino
- Department of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoya UniversityNagoyaJapan
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27
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Scheen AJ, Paquot N, Lefèbvre PJ. Investigational glucagon receptor antagonists in Phase I and II clinical trials for diabetes. Expert Opin Investig Drugs 2017; 26:1373-1389. [PMID: 29052441 DOI: 10.1080/13543784.2017.1395020] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Despite type 2 diabetes (T2D) being recognized as a bihormonal pancreatic disease, current therapies are mainly focusing on insulin, while targeting glucagon has been long dismissed. However, glucagon receptor (GCGr) antagonists are currently investigated in clinical trials. Area covered: Following a brief description of the rationale for antagonizing GCGr in T2D, lessons from GCGr knock-out mice and pharmacological means to antagonize GCGr, a detailed description of the main results obtained with GCGr antagonists in Phase I-II clinical trials is provided. The development of several small molecules has been discontinued, while new ones are currently considered as well as innovative approaches such as monoclonal antibodies or antisense oligonucleotides inhibiting GCGr gene expression. Their potential benefits but also limitations are discussed. Expert opinion: The proof-of-concept that antagonizing GCGr improves glucose control in T2D has been confirmed in humans. Nevertheless, some adverse events led to stopping the development of some of these GCGr antagonists. New approaches seem to have a better benefit/risk balance, although none has progressed to Phase III clinical trials so far. Pharmacotherapy of T2D is becoming a highly competitive field so that GCGr antagonists should provide clear advantages over numerous existing glucose-lowering medications before eventually reaching clinical practice.
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Affiliation(s)
- André J Scheen
- a Division of Clinical Pharmacology , Center for Interdisciplinary Research on Medicines (CIRM), University of Liège , Belgium.,b Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine , CHU , Liège , Belgium
| | - Nicolas Paquot
- b Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine , CHU , Liège , Belgium
| | - Pierre J Lefèbvre
- b Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine , CHU , Liège , Belgium
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28
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Dean ED, Li M, Prasad N, Wisniewski SN, Von Deylen A, Spaeth J, Maddison L, Botros A, Sedgeman LR, Bozadjieva N, Ilkayeva O, Coldren A, Poffenberger G, Shostak A, Semich MC, Aamodt KI, Phillips N, Yan H, Bernal-Mizrachi E, Corbin JD, Vickers KC, Levy SE, Dai C, Newgard C, Gu W, Stein R, Chen W, Powers AC. Interrupted Glucagon Signaling Reveals Hepatic α Cell Axis and Role for L-Glutamine in α Cell Proliferation. Cell Metab 2017; 25:1362-1373.e5. [PMID: 28591638 PMCID: PMC5572896 DOI: 10.1016/j.cmet.2017.05.011] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 03/15/2017] [Accepted: 05/23/2017] [Indexed: 02/06/2023]
Abstract
Decreasing glucagon action lowers the blood glucose and may be useful therapeutically for diabetes. However, interrupted glucagon signaling leads to α cell proliferation. To identify postulated hepatic-derived circulating factor(s) responsible for α cell proliferation, we used transcriptomics/proteomics/metabolomics in three models of interrupted glucagon signaling and found that proliferation of mouse, zebrafish, and human α cells was mTOR and FoxP transcription factor dependent. Changes in hepatic amino acid (AA) catabolism gene expression predicted the observed increase in circulating AAs. Mimicking these AA levels stimulated α cell proliferation in a newly developed in vitro assay with L-glutamine being a critical AA. α cell expression of the AA transporter Slc38a5 was markedly increased in mice with interrupted glucagon signaling and played a role in α cell proliferation. These results indicate a hepatic α islet cell axis where glucagon regulates serum AA availability and AAs, especially L-glutamine, regulate α cell proliferation and mass via mTOR-dependent nutrient sensing.
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Affiliation(s)
- E Danielle Dean
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Mingyu Li
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; School of Pharmaceutical Sciences, Xiamen University, Xiamen 361005, China
| | - Nripesh Prasad
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Scott N Wisniewski
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alison Von Deylen
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jason Spaeth
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lisette Maddison
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Anthony Botros
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Leslie R Sedgeman
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Nadejda Bozadjieva
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Health System, Ann Arbor, MI 48103, USA
| | - Olga Ilkayeva
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, NC 27701, USA
| | - Anastasia Coldren
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Greg Poffenberger
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alena Shostak
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Michael C Semich
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kristie I Aamodt
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Neil Phillips
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Hai Yan
- REMD Biotherapeutics, Camarillo, CA 93012, USA
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miami, FL 33146, USA
| | - Jackie D Corbin
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kasey C Vickers
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Shawn E Levy
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Chunhua Dai
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Christopher Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, NC 27701, USA
| | - Wei Gu
- Amgen, Thousand Oaks, CA 91320, USA
| | - Roland Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Wenbiao Chen
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alvin C Powers
- Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; VA Tennessee Valley Healthcare, Nashville, TN 37212, USA.
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29
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Müller TD, Finan B, Clemmensen C, DiMarchi RD, Tschöp MH. The New Biology and Pharmacology of Glucagon. Physiol Rev 2017; 97:721-766. [PMID: 28275047 DOI: 10.1152/physrev.00025.2016] [Citation(s) in RCA: 206] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the last two decades we have witnessed sizable progress in defining the role of gastrointestinal signals in the control of glucose and energy homeostasis. Specifically, the molecular basis of the huge metabolic benefits in bariatric surgery is emerging while novel incretin-based medicines based on endogenous hormones such as glucagon-like peptide 1 and pancreas-derived amylin are improving diabetes management. These and related developments have fostered the discovery of novel insights into endocrine control of systemic metabolism, and in particular a deeper understanding of the importance of communication across vital organs, and specifically the gut-brain-pancreas-liver network. Paradoxically, the pancreatic peptide glucagon has reemerged in this period among a plethora of newly identified metabolic macromolecules, and new data complement and challenge its historical position as a gut hormone involved in metabolic control. The synthesis of glucagon analogs that are biophysically stable and soluble in aqueous solutions has promoted biological study that has enriched our understanding of glucagon biology and ironically recruited glucagon agonism as a central element to lower body weight in the treatment of metabolic disease. This review summarizes the extensive historical record and the more recent provocative direction that integrates the prominent role of glucagon in glucose elevation with its under-acknowledged effects on lipids, body weight, and vascular health that have implications for the pathophysiology of metabolic diseases, and the emergence of precision medicines to treat metabolic diseases.
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Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - B Finan
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - C Clemmensen
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - R D DiMarchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - M H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
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30
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Holst JJ, Holland W, Gromada J, Lee Y, Unger RH, Yan H, Sloop KW, Kieffer TJ, Damond N, Herrera PL. Insulin and Glucagon: Partners for Life. Endocrinology 2017; 158:696-701. [PMID: 28323959 PMCID: PMC6061217 DOI: 10.1210/en.2016-1748] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/25/2017] [Indexed: 12/28/2022]
Abstract
In August 2016, several leaders in glucagon biology gathered for the European Association for the Study of Diabetes Hagedorn Workshop in Oxford, England. A key point of discussion focused on the need for basal insulin to allow for the therapeutic benefit of glucagon blockade in the treatment of diabetes. Among the most enlightening experimental results presented were findings from studies in which glucagon receptor-deficient mice were administered streptozotocin to destroy pancreatic β cells or had undergone diphtheria toxin-induced β cell ablation. This article summarizes key features of the discussion as a consensus was reached. Agents that antagonize glucagon may be of great benefit for the treatment of diabetes; however, sufficient levels of basal insulin are required for their therapeutic efficacy.
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Affiliation(s)
- Jens Juul Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - William Holland
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | | | - Young Lee
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Roger H Unger
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Hai Yan
- REMD Biotherapeutics Inc., Camarillo, California
| | - Kyle W Sloop
- Endocrine Discovery, Lilly Research Laboratories, Indianapolis, Indiana
| | - Timothy J Kieffer
- Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicolas Damond
- Department of Genetic Medicine & Development, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Pedro L Herrera
- Department of Genetic Medicine & Development, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
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31
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Wewer Albrechtsen NJ, Kuhre RE, Pedersen J, Knop FK, Holst JJ. The biology of glucagon and the consequences of hyperglucagonemia. Biomark Med 2016; 10:1141-1151. [PMID: 27611762 DOI: 10.2217/bmm-2016-0090] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The proglucagon-derived peptide hormone, glucagon, comprises 29 amino acids. Its secretion from the pancreatic α cells is regulated by several factors. Glucagon increases blood glucose levels through gluconeogenesis and glycogenolysis. Elevated plasma concentrations of glucagon, hyperglucagonemia, may contribute to diabetes. However, hyperglucagonemia is also observed in other clinical conditions than diabetes, including nonalcoholic fatty liver disease, glucagon-producing tumors and after gastric bypass surgery. Here, we review the current literature on hyperglucagonemia in disease with a particular focus on diabetes, and finally speculate that the primary physiological importance of glucagon may not reside in glucose homeostasis but in regulation of amino acid metabolism exerted via a hitherto unrecognized hepato-pancreatic feedback loop.
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Affiliation(s)
- Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Rune E Kuhre
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Filip K Knop
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark.,Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
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32
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Bankir L, Bouby N, Blondeau B, Crambert G. Glucagon actions on the kidney revisited: possible role in potassium homeostasis. Am J Physiol Renal Physiol 2016; 311:F469-86. [DOI: 10.1152/ajprenal.00560.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/31/2016] [Indexed: 12/25/2022] Open
Abstract
It is now recognized that the metabolic disorders observed in diabetes are not, or not only due to the lack of insulin or insulin resistance, but also to elevated glucagon secretion. Accordingly, selective glucagon receptor antagonists are now proposed as a novel strategy for the treatment of diabetes. However, besides its metabolic actions, glucagon also influences kidney function. The glucagon receptor is expressed in the thick ascending limb, distal tubule, and collecting duct, and glucagon regulates the transepithelial transport of several solutes in these nephron segments. Moreover, it also influences solute transport in the proximal tubule, possibly by an indirect mechanism. This review summarizes the knowledge accumulated over the last 30 years about the influence of glucagon on the renal handling of electrolytes and urea. It also describes a possible novel role of glucagon in the short-term regulation of potassium homeostasis. Several original findings suggest that pancreatic α-cells may express a “potassium sensor” sensitive to changes in plasma K concentration and could respond by adapting glucagon secretion that, in turn, would regulate urinary K excretion. By their combined actions, glucagon and insulin, working in a combinatory mode, could ensure an independent regulation of both plasma glucose and plasma K concentrations. The results and hypotheses reviewed here suggest that the use of glucagon receptor antagonists for the treatment of diabetes should take into account their potential consequences on electrolyte handling by the kidney.
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Affiliation(s)
- Lise Bankir
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre et Marie Curie, Paris, France; and
| | - Nadine Bouby
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre et Marie Curie, Paris, France; and
- Université Paris-Descartes, Paris, France
| | - Bertrand Blondeau
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre et Marie Curie, Paris, France; and
| | - Gilles Crambert
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre et Marie Curie, Paris, France; and
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33
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Rhyu J, Yu R. Mahvash disease: an autosomal recessive hereditary pancreatic neuroendocrine tumor syndrome. INTERNATIONAL JOURNAL OF ENDOCRINE ONCOLOGY 2016. [DOI: 10.2217/ije-2016-0005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Jane Rhyu
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Division of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, CA, USA; current address Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, USA,
| | - Run Yu
- Division of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, CA, USA; current address Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, USA,
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34
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McShane LM, Irwin N, O'Flynn D, Franklin ZJ, Hewage CM, O'Harte FPM. Glucagon receptor antagonist and GIP agonist combination for diet-induced obese mice. J Endocrinol 2016; 229:319-30. [PMID: 27098830 DOI: 10.1530/joe-15-0463] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 04/19/2016] [Indexed: 12/13/2022]
Abstract
Ablation of glucagon receptor signaling represents a potential treatment option for type 2 diabetes (T2DM). Additionally, activation of glucose-dependent insulinotropic polypeptide (GIP) receptor signaling also holds therapeutic promise for T2DM. Therefore, this study examined both independent and combined metabolic actions of desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon (glucagon receptor antagonist) and d-Ala(2)GIP (GIP receptor agonist) in diet-induced obese mice. Glucagon receptor binding has been linked to alpha-helical structure and desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon displayed enhanced alpha-helical content compared with native glucagon. In clonal pancreatic BRIN-BD11 beta-cells, desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon was devoid of any insulinotropic or cAMP-generating actions, and did not impede d-Ala(2)GIP-mediated (P<0.01 to P<0.001) effects on insulin and cAMP production. Twice-daily injection of desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon or d-Ala(2)GIP alone, and in combination, in high-fat-fed mice failed to affect body weight or energy intake. Circulating blood glucose levels were significantly (P<0.05 to P<0.01) decreased by all treatments regimens, with plasma and pancreatic insulin elevated (P<0.05 to P<0.001) in all mice receiving d-Ala(2)GIP. Interestingly, plasma glucagon concentrations were decreased (P<0.05) by sustained glucagon inhibition (day 28), but increased (P<0.05) by d-Ala(2)GIP therapy, with a combined treatment resulting in glucagon concentration similar to saline controls. All treatments improved (P<0.01) intraperitoneal and oral glucose tolerance, and peripheral insulin sensitivity. d-Ala(2)GIP-treated mice showed increased glucose-induced insulin secretion in response to intraperitoneal and oral glucose. Metabolic rate and ambulatory locomotor activity were increased (P<0.05 to P<0.001) in all desHis(1)Pro(4)Glu(9)(Lys(12)PAL)-glucagon-treated mice. These studies highlight the potential of glucagon receptor inhibition alone, and in combination with GIP receptor activation, for T2DM treatment.
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Affiliation(s)
- L M McShane
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Coleraine, Northern Ireland, UK
| | - N Irwin
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Coleraine, Northern Ireland, UK
| | - D O'Flynn
- Conway Institute of Biomolecular and Biomedical ResearchUCD, Belfield, Dublin 4, Ireland
| | - Z J Franklin
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Coleraine, Northern Ireland, UK
| | - C M Hewage
- Conway Institute of Biomolecular and Biomedical ResearchUCD, Belfield, Dublin 4, Ireland
| | - F P M O'Harte
- SAAD Centre for Pharmacy and DiabetesUniversity of Ulster, Coleraine, Northern Ireland, UK
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35
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Yu R. Animal models of spontaneous pancreatic neuroendocrine tumors. Mol Cell Endocrinol 2016; 421:60-7. [PMID: 26261055 DOI: 10.1016/j.mce.2015.08.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/10/2015] [Accepted: 08/04/2015] [Indexed: 01/20/2023]
Abstract
Pancreatic neuroendocrine tumors (PNETs) are usually low-grade neoplasms derived from the endocrine pancreas. PNETs can be functioning and cause well-described hormonal hypersecretion syndromes or non-functioning and cause only tumor mass effect. PNETs appear to be more common recently likely due to incidental detection by imaging. Although the diagnosis and management of PNETs have been evolving rapidly, much remains to be studied in the areas of molecular pathogenesis, molecular markers of tumor behavior, early detection, and targeted drug therapy. Unique challenges facing PNETs studies are long disease course, the deep location of pancreas and difficult access to pancreatic tissue, and the variety of tumors, which make animal models valuable tools for PNETs studies. Existing animal models of PNETs have provided insights into the pathogenesis and natural history of human PNETs. Future studies on animal models of PNETs should address early tumor detection, molecular markers of tumor behavior, and novel targeted therapies.
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Affiliation(s)
- Run Yu
- Division of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
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Abstract
OBJECTIVE There is general recognition that insulin and glucagon are the main hormones involved in the pathophysiology of diabetes, but the role of glucagon in diabetes is complex and in some circumstances controversial. The increasing appreciation of the role of glucagon in currently used hypoglycemic agents and the ongoing development of glucagon-targeted therapies underscores glucagon's important contribution in optimizing diabetes management. The current review provides a background on glucagon physiology and pathophysiology and an update for investigators, endocrinologists, and other healthcare providers on glucagon-modulating therapies. METHODS A literature review was conducted utilizing published literature in PubMed and AccessMedicine including the years 1922-2015 using the following key words: glucagon, bihormonal, diabetes mellitus, glucagon antagonists, glucagon-targeted therapies. RESULTS Glucagon is a counterregulatory hormone that promotes hepatic glucose production, thus preventing hypoglycemia in normal physiology. In patients with diabetes mellitus, glucagon secretion may be unregulated, which contributes to problems with glucose homeostasis. Several of the most effective therapies for diabetes have been found to suppress glucagon secretion or action, which may contribute to their success. Additionally, glucagon-specific targeted therapies, such as glucagon receptor antagonists, are being studied at a basic and clinical level. CONCLUSION Glucagon plays an important role in contributing to hyperglycemia in patients with diabetes. Utilizing hypoglycemic agents that decrease glucagon secretion or inhibit glucagon action can help improve glycemic control, making these agents a valuable resource in diabetes therapy.
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Takagi Y, Kinoshita K, Ozaki N, Seino Y, Murata Y, Oshida Y, Hayashi Y. Mice Deficient in Proglucagon-Derived Peptides Exhibit Glucose Intolerance on a High-Fat Diet but Are Resistant to Obesity. PLoS One 2015; 10:e0138322. [PMID: 26378455 PMCID: PMC4574859 DOI: 10.1371/journal.pone.0138322] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/28/2015] [Indexed: 01/26/2023] Open
Abstract
Homozygous glucagon-GFP knock-in mice (Gcggfp/gfp) lack proglucagon derived-peptides including glucagon and GLP-1, and are normoglycemic. We have previously shown that Gcggfp/gfp show improved glucose tolerance with enhanced insulin secretion. Here, we studied glucose and energy metabolism in Gcggfp/gfp mice fed a high-fat diet (HFD). Male Gcggfp/gfp and Gcggfp/+ mice were fed either a normal chow diet (NCD) or an HFD for 15–20 weeks. Regardless of the genotype, mice on an HFD showed glucose intolerance, and Gcggfp/gfp mice on HFD exhibited impaired insulin secretion whereas Gcggfp/+ mice on HFD exhibited increased insulin secretion. A compensatory increase in β-cell mass was observed in Gcggfp/+mice on HFD, but not in Gcggfp/gfp mice on the same diet. Weight gain was significantly lower in Gcggfp/gfp mice than in Gcggfp/+mice. Oxygen consumption was enhanced in Gcggfp/gfp mice compared to Gcggfp/+ mice on an HFD. HFD feeding significantly increased uncoupling protein 1 mRNA expression in brown adipose and inguinal white adipose tissues of Gcggfp/gfp mice, but not of Gcggfp/+mice. Treatment with the glucagon-like peptide-1 receptor agonist liraglutide (200 mg/kg) improved glucose tolerance in Gcggfp/gfp mice and insulin content in Gcggfp/gfp and Gcggfp/+ mice was similar after liraglutide treatment. Our findings demonstrate that Gcggfp/gfp mice develop diabetes upon HFD-feeding in the absence of proglucagon-derived peptides, although they are resistant to diet-induced obesity.
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Affiliation(s)
- Yusuke Takagi
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Keita Kinoshita
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Nobuaki Ozaki
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
- * E-mail:
| | - Yusuke Seino
- Department of Metabolic Medicine, Nagoya University School of Medicine, Nagoya, Japan
| | - Yoshiharu Murata
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Yoshiharu Oshida
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
| | - Yoshitaka Hayashi
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
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Sandoval DA, D'Alessio DA. Physiology of proglucagon peptides: role of glucagon and GLP-1 in health and disease. Physiol Rev 2015; 95:513-48. [PMID: 25834231 DOI: 10.1152/physrev.00013.2014] [Citation(s) in RCA: 310] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The preproglucagon gene (Gcg) is expressed by specific enteroendocrine cells (L-cells) of the intestinal mucosa, pancreatic islet α-cells, and a discrete set of neurons within the nucleus of the solitary tract. Gcg encodes multiple peptides including glucagon, glucagon-like peptide-1, glucagon-like peptide-2, oxyntomodulin, and glicentin. Of these, glucagon and GLP-1 have received the most attention because of important roles in glucose metabolism, involvement in diabetes and other disorders, and application to therapeutics. The generally accepted model is that GLP-1 improves glucose homeostasis indirectly via stimulation of nutrient-induced insulin release and by reducing glucagon secretion. Yet the body of literature surrounding GLP-1 physiology reveals an incompletely understood and complex system that includes peripheral and central GLP-1 actions to regulate energy and glucose homeostasis. On the other hand, glucagon is established principally as a counterregulatory hormone, increasing in response to physiological challenges that threaten adequate blood glucose levels and driving glucose production to restore euglycemia. However, there also exists a potential role for glucagon in regulating energy expenditure that has recently been suggested in pharmacological studies. It is also becoming apparent that there is cross-talk between the proglucagon derived-peptides, e.g., GLP-1 inhibits glucagon secretion, and some additive or synergistic pharmacological interaction between GLP-1 and glucagon, e.g., dual glucagon/GLP-1 agonists cause more weight loss than single agonists. In this review, we discuss the physiological functions of both glucagon and GLP-1 by comparing and contrasting how these peptides function, variably in concert and opposition, to regulate glucose and energy homeostasis.
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Affiliation(s)
- Darleen A Sandoval
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - David A D'Alessio
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
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Kelly RP, Garhyan P, Raddad E, Fu H, Lim CN, Prince MJ, Pinaire JA, Loh MT, Deeg MA. Short-term administration of the glucagon receptor antagonist LY2409021 lowers blood glucose in healthy people and in those with type 2 diabetes. Diabetes Obes Metab 2015; 17:414-22. [PMID: 25656305 DOI: 10.1111/dom.12446] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/29/2015] [Accepted: 01/31/2015] [Indexed: 11/30/2022]
Abstract
AIM To describe the clinical effects of single and multiple doses of a potent, selective, orally administered, small-molecule antagonist of the human glucagon receptor, LY2409021, in healthy subjects and in patients with type 2 diabetes. METHODS LY2409021 was administered in dose-escalation studies to healthy subjects (n = 23) and patients with type 2 diabetes (n = 9) as single doses (Study 1) and daily to patients with type 2 diabetes (n = 47) for 28 days (Study 2). Safety, tolerability, pharmacokinetic (PK) and pharmacodynamic (PD) assessments were made after single doses and in patients receiving once-daily doses of LY2409021 (5, 30, 60 or 90 mg) for 28 days. RESULTS LY2409021 was well tolerated at all dose levels in both studies. Fasting and postprandial glucose were reduced and glucagon levels increased after single and multiple dosing, with reductions in fasting serum glucose of up to ∼1.25 mmol/l on day 28. Serum aminotransferases increased in a dose-dependent manner with multiple dosing and reversed after cessation of dosing. Significant glucose-lowering was observed with LY2409021 at dose levels associated with only minor aminotransferase increases. CONCLUSION Blockade of glucagon signalling in patients with type 2 diabetes is well tolerated and results in substantial reduction of fasting and postprandial glucose with minimal hypoglycaemia, but with reversible increases in aminotransferases. Inhibition of glucagon signalling by LY2409021 is a promising potential treatment for patients with type 2 diabetes and should be evaluated in longer clinical trials to better evaluate benefits and risks.
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Affiliation(s)
- R P Kelly
- Lilly-NUS, Clinical Research Centre, National University of Singapore, 10 Medical Drive, 117597, Singapore
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Jun LS, Millican RL, Hawkins ED, Konkol DL, Showalter AD, Christe ME, Michael MD, Sloop KW. Absence of glucagon and insulin action reveals a role for the GLP-1 receptor in endogenous glucose production. Diabetes 2015; 64:819-27. [PMID: 25288673 DOI: 10.2337/db14-1052] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The absence of insulin results in oscillating hyperglycemia and ketoacidosis in type 1 diabetes. Remarkably, mice genetically deficient in the glucagon receptor (Gcgr) are refractory to the pathophysiological symptoms of insulin deficiency, and therefore, studies interrogating this unique model may uncover metabolic regulatory mechanisms that are independent of insulin. A significant feature of Gcgr-null mice is the high circulating concentrations of GLP-1. Hence, the objective of this report was to investigate potential noninsulinotropic roles of GLP-1 in mice where GCGR signaling is inactivated. For these studies, pancreatic β-cells were chemically destroyed by streptozotocin (STZ) in Gcgr(-/-):Glp-1r(-/-) mice and in Glp-1r(-/-) animals that were subsequently treated with a high-affinity GCGR antagonist antibody that recapitulates the physiological state of Gcgr ablation. Loss of GLP-1 action substantially worsened nonfasting glucose concentrations and glucose tolerance in mice deficient in, and undergoing pharmacological inhibition of, the GCGR. Further, lack of the Glp-1r in STZ-treated Gcgr(-/-) mice elevated rates of endogenous glucose production, likely accounting for the differences in glucose homeostasis. These results support the emerging hypothesis that non-β-cell actions of GLP-1 analogs may improve metabolic control in patients with insulinopenic diabetes.
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Affiliation(s)
- Lucy S Jun
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Rohn L Millican
- BioTechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Eric D Hawkins
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Debra L Konkol
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Aaron D Showalter
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Michael E Christe
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - M Dodson Michael
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - Kyle W Sloop
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
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Mittermayer F, Caveney E, De Oliveira C, Gourgiotis L, Puri M, Tai LJ, Turner JR. Addressing unmet medical needs in type 2 diabetes: a narrative review of drugs under development. Curr Diabetes Rev 2015; 11:17-31. [PMID: 25537454 PMCID: PMC4428473 DOI: 10.2174/1573399810666141224121927] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 12/12/2014] [Accepted: 12/19/2014] [Indexed: 12/19/2022]
Abstract
The global burden of type 2 diabetes is increasing worldwide, and successful treatment of this disease needs constant provision of new drugs. Twelve classes of antidiabetic drugs are currently available, and many new drugs are under clinical development. These include compounds with known mechanisms of action but unique properties, such as once-weekly DPP4 inhibitors or oral insulin. They also include drugs with new mechanisms of action, the focus of this review. Most of these compounds are in Phase 1 and 2, with only a small number having made it to Phase 3 at this time. The new drug classes described include PPAR agonists/modulators, glucokinase activators, glucagon receptor antagonists, anti-inflammatory compounds, G-protein coupled receptor agonists, gastrointestinal peptide agonists other than GLP-1, apical sodium-dependent bile acid transporter (ASBT) inhibitors, SGLT1 and dual SGLT1/SGLT2 inhibitors, and 11beta- HSD1 inhibitors.
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Affiliation(s)
| | | | | | | | | | | | - J Rick Turner
- Quintiles GmbH, Stella- Klein-Low Weg 15, Rund 4, Haus B, OG 4, 1020 Vienna, Austria.
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Lotfy M, Kalasz H, Szalai G, Singh J, Adeghate E. Recent Progress in the Use of Glucagon and Glucagon Receptor Antago-nists in the Treatment of Diabetes Mellitus. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2014; 8:28-35. [PMID: 25674162 PMCID: PMC4321206 DOI: 10.2174/1874104501408010028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 10/08/2014] [Accepted: 10/12/2014] [Indexed: 12/25/2022]
Abstract
Glucagon is an important pancreatic hormone, released into blood circulation by alpha cells of the islet of
Langerhans. Glucagon induces gluconeogenesis and glycogenolysis in hepatocytes, leading to an increase in hepatic glucose
production and subsequently hyperglycemia in susceptible individuals. Hyperglucagonemia is a constant feature in
patients with T2DM. A number of bioactive agents that can block glucagon receptor have been identified. These glucagon
receptor antagonists can reduce the hyperglycemia associated with exogenous glucagon administration in normal as well
as diabetic subjects. Glucagon receptor antagonists include isoserine and beta-alanine derivatives, bicyclic 19-residue peptide
BI-32169, Des-His1-[Glu9] glucagon amide and related compounds, 5-hydroxyalkyl-4-phenylpyridines, N-[3-cano-6-
(1,1 dimethylpropyl)-4,5,6,7-tetrahydro-1-benzothien-2-yl]-2-ethylbutamide, Skyrin and NNC 250926. The absorption,
dosage, catabolism, excretion and medicinal chemistry of these agents are the subject of this review. It emphasizes the
role of glucagon in glucose homeostasis and how it could be applied as a novel tool for the management of diabetes mellitus
by blocking its receptors with either monoclonal antibodies, peptide and non-peptide antagonists or gene knockout
techniques.
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Affiliation(s)
- Mohamed Lotfy
- Department of Biology, College of Science, United Arab Emirates University; School of Forensic and Investigative Sciences, University of Central Lancashire, Preston PR1 2HE, England, UK; National Research Centre, Hormones Department, Cairo, Egypt
| | - Huba Kalasz
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Gyorgy Szalai
- ENT Department, St. Janos Hospital, Budapest, Hungary
| | - Jaipaul Singh
- School of Forensic and Investigative Sciences and School of Pharmacy and Biomedical Science, University of Central Lancashire, Preston PR1 2HE, England, UK
| | - Ernest Adeghate
- Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Ar-ab Emirates
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Abstract
The liver is an essential metabolic organ, and its metabolic function is controlled by insulin and other metabolic hormones. Glucose is converted into pyruvate through glycolysis in the cytoplasm, and pyruvate is subsequently oxidized in the mitochondria to generate ATP through the TCA cycle and oxidative phosphorylation. In the fed state, glycolytic products are used to synthesize fatty acids through de novo lipogenesis. Long-chain fatty acids are incorporated into triacylglycerol, phospholipids, and/or cholesterol esters in hepatocytes. These complex lipids are stored in lipid droplets and membrane structures, or secreted into the circulation as very low-density lipoprotein particles. In the fasted state, the liver secretes glucose through both glycogenolysis and gluconeogenesis. During pronged fasting, hepatic gluconeogenesis is the primary source for endogenous glucose production. Fasting also promotes lipolysis in adipose tissue, resulting in release of nonesterified fatty acids which are converted into ketone bodies in hepatic mitochondria though β-oxidation and ketogenesis. Ketone bodies provide a metabolic fuel for extrahepatic tissues. Liver energy metabolism is tightly regulated by neuronal and hormonal signals. The sympathetic system stimulates, whereas the parasympathetic system suppresses, hepatic gluconeogenesis. Insulin stimulates glycolysis and lipogenesis but suppresses gluconeogenesis, and glucagon counteracts insulin action. Numerous transcription factors and coactivators, including CREB, FOXO1, ChREBP, SREBP, PGC-1α, and CRTC2, control the expression of the enzymes which catalyze key steps of metabolic pathways, thus controlling liver energy metabolism. Aberrant energy metabolism in the liver promotes insulin resistance, diabetes, and nonalcoholic fatty liver diseases.
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Affiliation(s)
- Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan
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44
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O'Harte FPM, Franklin ZJ, Irwin N. Two novel glucagon receptor antagonists prove effective therapeutic agents in high-fat-fed and obese diabetic mice. Diabetes Obes Metab 2014; 16:1214-22. [PMID: 25060150 DOI: 10.1111/dom.12360] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 07/03/2014] [Accepted: 07/19/2014] [Indexed: 11/30/2022]
Abstract
AIMS To examine the effect of two novel, enzymatically stable, glucagon receptor peptide antagonists, on metabolic control in two mouse models of obesity/diabetes. METHOD The effects of twice daily i.p. administration of desHis(1)Pro(4)Glu(9)-glucagon or desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon for 10 days on metabolic control in high-fat-fed (HFF; 45% fat) and obese diabetic (ob/ob) mice were compared with saline-treated controls. RESULTS Neither analogue altered body weight or food intake in either model over 10 days; however, treatment with each peptide restored non-fasting blood glucose towards normal control values in HFF mice. Basal glucose was also reduced (p < 0.01) in desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon treated ob/ob mice by day 10, coinciding with increases (p < 0.001) in circulating insulin. At the end of the treatment period, both analogues significantly (p < 0.05-0.01) improved oral and i.p. glucose tolerance (p < 0.05) and peripheral insulin sensitivity, increased pancreatic insulin and glucagon content (p < 0.05-0.01) and decreased (p < 0.05) cholesterol levels in HFF mice. Similarly beneficial metabolic effects on oral glucose tolerance (p < 0.01) and pancreatic insulin content (p < 0.05) were observed in ob/ob mice, especially after desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon treatment. No significant differences in circulating triglycerides or aspects of indirect calorimetry were noted between peptide treatment groups and respective control HFF and ob/ob mice. Finally, glucagon-mediated elevations of glucose and insulin were significantly (p < 0.05-0.01) annulled after 10 days of desHis(1)Pro(4)Glu(9)-glucagon or desHis(1)Pro(4)Glu(9)Lys(12)FA-glucagon treatment in both animal models. CONCLUSION These data indicate that peptide-based glucagon receptor antagonists can reverse aspects of genetically and dietary-induced obesity-related diabetes.
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Affiliation(s)
- F P M O'Harte
- The Saad Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK
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McShane LM, Franklin ZJ, O'Harte FPM, Irwin N. Ablation of glucagon receptor signaling by peptide-based glucagon antagonists improves glucose tolerance in high fat fed mice. Peptides 2014; 60:95-101. [PMID: 25148830 DOI: 10.1016/j.peptides.2014.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/06/2014] [Accepted: 08/06/2014] [Indexed: 01/21/2023]
Abstract
Modification to the structure of glucagon has provided a number of glucagon receptor antagonists with possible therapeutic application for diabetes. These novel peptide analogs include desHis(1)Pro(4)Glu(9)-glucagon and desHis(1)Pro(4)Glu(9)(Lys(30)PAL)-glucagon. This study has evaluated the metabolic benefits of once daily administration of desHis(1)Pro(4)Glu(9)-glucagon and desHis(1)Pro(4)Glu(9)(Lys(30)PAL)-glucagon in high fat (45%) fed mice for 15 days. Administration of desHis(1)Pro(4)Glu(9)-glucagon and desHis(1)Pro(4)Glu(9)(Lys(30)PAL)-glucagon had no significant effect on body weight, food intake or circulating glucose concentrations during the treatment period. However, both peptides significantly (P<0.05 to P<0.01) reduced circulating plasma insulin concentrations from day 6 onwards. Oral glucose tolerance and insulin sensitivity, as assessed by exogenous insulin administration, were significantly (P<0.01 to P<0.001) improved by both desHis(1)Pro(4)Glu(9)-glucagon and desHis(1)Pro(4)Glu(9)(Lys(30)PAL)-glucagon. These metabolic benefits were accompanied by significantly (P<0.01) increased pancreatic insulin stores. No significant differences in blood triacylglycerol or cholesterol levels were noted with desHis(1)Pro(4)Glu(9)-glucagon, however desHis(1)Pro(4)Glu(9)(Lys(30)PAL)-glucagon treatment significantly (P<0.01) increased HDL-cholesterol levels. Glucagon-mediated elevations of glucose and insulin were effectively (P<0.01 to P<0.001) annulled in both treatment groups on day 15. Interestingly, glucose levels during an intraperitoneal glucose tolerance test were not altered by either desHis(1)Pro(4)Glu(9)-glucagon or desHis(1)Pro(4)Glu(9)(Lys(30)PAL)-glucagon treatment. These data provide further evidence that glucagon antagonism could provide an effective means of treating T2DM.
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Affiliation(s)
- Laura M McShane
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Zara J Franklin
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Finbarr P M O'Harte
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
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46
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Dhalla AK, Yang M, Ning Y, Kahlig KM, Krause M, Rajamani S, Belardinelli L. Blockade of Na+ channels in pancreatic α-cells has antidiabetic effects. Diabetes 2014; 63:3545-56. [PMID: 24812428 DOI: 10.2337/db13-1562] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pancreatic α-cells express voltage-gated Na(+) channels (NaChs), which support the generation of electrical activity leading to an increase in intracellular calcium, and cause exocytosis of glucagon. Ranolazine, a NaCh blocker, is approved for treatment of angina. In addition to its antianginal effects, ranolazine has been shown to reduce HbA1c levels in patients with type 2 diabetes mellitus and coronary artery disease; however, the mechanism behind its antidiabetic effect has been unclear. We tested the hypothesis that ranolazine exerts its antidiabetic effects by inhibiting glucagon release via blockade of NaChs in the pancreatic α-cells. Our data show that ranolazine, via blockade of NaChs in pancreatic α-cells, inhibits their electrical activity and reduces glucagon release. We found that glucagon release in human pancreatic islets is mediated by the Nav1.3 isoform. In animal models of diabetes, ranolazine and a more selective NaCh blocker (GS-458967) lowered postprandial and basal glucagon levels, which were associated with a reduction in hyperglycemia, confirming that glucose-lowering effects of ranolazine are due to the blockade of NaChs. This mechanism of action is unique in that no other approved antidiabetic drugs act via this mechanism, and raises the prospect that selective Nav1.3 blockers may constitute a novel approach for the treatment of diabetes.
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Affiliation(s)
- Arvinder K Dhalla
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
| | - Ming Yang
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
| | - Yun Ning
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
| | - Kristopher M Kahlig
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
| | - Michael Krause
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
| | - Sridharan Rajamani
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
| | - Luiz Belardinelli
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA
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47
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Franklin ZJ, O’Harte FP, Irwin N. Effects of short-term chemical ablation of glucagon signalling by peptide-based glucagon receptor antagonists on insulin secretion and glucose homeostasis in mice. Biol Chem 2014; 395:433-42. [DOI: 10.1515/hsz-2013-0224] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 11/04/2013] [Indexed: 11/15/2022]
Abstract
Abstract
Glucagon is a hormone with important effects on blood glucose regulation. This study has utilized the stable glucagon receptor antagonists, desHis1Pro4Glu9-glucagon and desHis1Pro4Glu9(Lys12PAL)-glucagon, to evaluate the effects of sustained inhibition of glucagon receptor signalling in normal mice. Twice-daily injection of either analogue for 10 days had no effect on food intake, body weight and non-fasting plasma glucose concentrations. However, insulin levels were significantly raised (p<0.05 to p<0.01) from day 3 onwards in desHis1Pro4Glu9-glucagon mice. After 10 days, glucose tolerance was improved (p<0.05) in desHis1Pro4Glu9-glucagon treated mice. Glucose-mediated insulin secretion and circulating cholesterol levels were significantly (p<0.05 to p<0.01) decreased in both treatment groups. Importantly, the effects of glucagon to increase blood glucose and insulin concentrations were still annulled on day 10. Insulin sensitivity was almost identical in all groups of mice at the end of the study. In addition, no changes in pancreatic insulin and glucagon content or islet morphology were observed in either treatment group. Finally, acute injection of desHis1Pro4Glu9-glucagon followed by a 24-h fast in treatment naïve mice was not associated with any hypoglycaemic episodes. These data indicate that peptide-based glucagon receptor antagonists represent safe and effective treatment options for type 2 diabetes.
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Jones HB, Reens J, Brocklehurst SR, Betts CJ, Bickerton S, Bigley AL, Jenkins RP, Whalley NM, Morgan D, Smith DM. Islets of Langerhans from prohormone convertase-2 knockout mice show α-cell hyperplasia and tumorigenesis with elevated α-cell neogenesis. Int J Exp Pathol 2014; 95:29-48. [PMID: 24456331 DOI: 10.1111/iep.12066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 11/14/2013] [Indexed: 01/24/2023] Open
Abstract
Antagonism of the effects of glucagon as an adjunct therapy with other glucose-lowering drugs in the chronic treatment of diabetes has been suggested to aggressively control blood glucose levels. Antagonism of glucagon effects, by targeting glucagon secretion or disabling the glucagon receptor, is associated with α-cell hyperplasia. We evaluated the influence of total glucagon withdrawal on islets of Langerhans using prohormone convertase-2 knockout mice (PC2-ko), in which α-cell hyperplasia is present from a young age and persists throughout life, in order to understand whether or not sustained glucagon deficit would lead to islet tumorigenesis. PC2-ko and wild-type (WT) mice were maintained drug-free, and cohorts of these groups sampled at 3, 12 and 18 months for plasma biochemical and morphological (histological, immunohistochemical, electron microscopical and image analytical) assessments. WT mice showed no islet tumours up to termination of the study, but PC2-ko animals displayed marked changes in islet morphology from α-cell hypertrophy/hyperplasia/atypical hyperplasia, to adenomas and carcinomas, these latter being first encountered at 6-8 months. Islet hyperplasias and tumours primarily consisted of α-cells associated to varying degrees with other islet endocrine cell types. In addition to substantial increases in islet neoplasia, increased α-cell neogenesis associated primarily with pancreatic duct(ule)s was present. We conclude that absolute blockade of the glucagon signal results in tumorigenesis and that the PC2-ko mouse represents a valuable model for investigation of islet tumours and pancreatic ductal neogenesis.
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Affiliation(s)
- Huw B Jones
- Department of Pathological Sciences, AstraZeneca Pharmaceuticals, Macclesfield, Cheshire, UK
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Abstract
CONTEXT Pancreatic α-cell hyperplasia (ACH) was once an esoteric pathological entity, but it has become an important differential diagnosis of hyperglucagonemia after inactivating glucagon receptor (GCGR) genomic mutations were found in patients with ACH. Recently, the controversy over the pancreatic effects of incretins has stimulated much discussion of ACH that often includes inaccurate statements not supported by the literature. DATA ACQUISITION Literature related to ACH was reviewed. EVIDENCE SYNTHESIS ACH is defined as a diffuse and specific increase in the number of α-cells. A dozen cases have been reported and fall into three clinical types: reactive, functional, and nonfunctional. Characterized by remarkable hyperglucagonemia without glucagonoma syndrome, reactive ACH is caused by inactivating GCGR mutations, and its main clinical significance is pancreatic neuroendocrine tumors diagnosed at middle age. The Gcgr(-/-) mice, a model of reactive ACH, exhibit a multistage tumorigenesis in their pancreata. Pharmacological agents that inhibit glucagon signaling also cause reactive ACH in animals and possibly in humans as well. The pancreata of incretin-treated humans and those of reactive ACH murine models share similarities. Functional ACH features hyperglucagonemia with glucagonoma syndrome. Nonfunctional ACH is associated with normal glucagon levels. The causes of functional and nonfunctional ACH are unknown as yet. CONCLUSIONS ACH is a histological diagnosis and clinically heterogeneous. Caused by GCGR mutations, reactive ACH is a preneoplastic lesion giving rise to slow-developing pancreatic neuroendocrine tumors. The effects of treatments targeting glucagon signaling in this regard remain controversial. The strong negative feedback control of glucagon signaling conserved in all mammals studied, including humans, makes long-term pancreatic tumor surveillance advisable for the glucagon signaling-targeting therapies.
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Affiliation(s)
- Run Yu
- Division of Endocrinology and Carcinoid and Neuroendocrine Tumor Center, Cedars-Sinai Medical Center, Los Angeles, California 90048
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Abstract
Glucagon-like peptide-1 (GLP-1), an incretin hormone secreted primarily from the intestinal L-cells in response to meals, modulates nutrient homeostasis via actions exerted in multiple tissues and cell types. GLP-1 and its analogs, as well as compounds that inhibit endogenous GLP-1 breakdown, have become an effective therapeutic strategy for many subjects with type 2 diabetes. Here we review the discovery of GLP-1; its synthesis, secretion, and elimination from the circulation; and its multiple pancreatic and extrapancreatic effects. Finally, we review current options for GLP-1-based diabetes therapy, including GLP-1 receptor agonism and inhibition of GLP-1 breakdown, as well as the benefits and drawbacks of different modes of therapy and the potential for new therapeutic avenues.
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Affiliation(s)
- Young Min Cho
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea;
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