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Zhou F, Sheng C, Ma X, Li T, Ming X, Wang S, Tan J, Yang Y, Sun H, Lu J, Liu J, Deng R, Wang X, Zhou L. BCKDH kinase promotes hepatic gluconeogenesis independent of BCKDHA. Cell Death Dis 2024; 15:736. [PMID: 39389936 PMCID: PMC11467410 DOI: 10.1038/s41419-024-07071-0] [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: 03/30/2024] [Revised: 09/01/2024] [Accepted: 09/12/2024] [Indexed: 10/12/2024]
Abstract
Elevated circulating branched-chain amino acids (BCAAs) are tightly linked to an increased risk in the development of type 2 diabetes mellitus. The rate limiting enzyme of BCAA catabolism branched-chain α-ketoacid dehydrogenase (BCKDH) is phosphorylated at E1α subunit (BCKDHA) by its kinase (BCKDK) and inactivated. Here, the liver-specific BCKDK or BCKDHA knockout mice displayed normal glucose tolerance and insulin sensitivity. However, knockout of BCKDK in the liver inhibited hepatic glucose production as well as the expression of key gluconeogenic enzymes. No abnormal gluconeogenesis was found in mice lacking hepatic BCKDHA. Consistent with the vivo results, BT2-mediated inhibition or genetic knockdown of BCKDK decreased hepatic glucose production and gluconeogenic gene expressions in primary mouse hepatocytes while BCKDK overexpression exhibited an opposite effect. Whereas, gluconeogenic gene expressions were not altered in BCKDHA-silenced hepatocytes. Mechanistically, BT2 treatment attenuated the interaction of cAMP response element binding protein (CREB) with CREB-binding protein and promoted FOXO1 protein degradation by increasing its ubiquitination. Our findings suggest that BCKDK regulates hepatic gluconeogenesis through CREB and FOXO1 signalings, independent of BCKDHA-mediated BCAA catabolism.
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Affiliation(s)
- Feiye Zhou
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Department of Endocrine and Metabolic Diseases, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Chunxiang Sheng
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xiaoqin Ma
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Tianjiao Li
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xing Ming
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Shushu Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jialin Tan
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yulin Yang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Haipeng Sun
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Center for Cardiovascular Diseases, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, 300134, China
| | - Jieli Lu
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jianmin Liu
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Ruyuan Deng
- Department of Gastroenterology and Hepatology, Zhongshan Hospital, Fudan University, 200032, China; Shanghai Institute of Liver Disease, Shanghai, 200032, China.
| | - Xiao Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Libin Zhou
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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Kitamura T, Kobayashi M. Advances in the clinical measurement of glucagon: from diagnosis to therapy. Diabetol Int 2024; 15:362-369. [PMID: 39101188 PMCID: PMC11291789 DOI: 10.1007/s13340-024-00704-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 02/19/2024] [Indexed: 08/06/2024]
Abstract
Glucagon has many functions: it promotes glucose production, fatty acid oxidation, thermogenesis, energy consumption, lipolysis, and myocardial contraction, and suppresses lipogenesis, appetite, and gastrointestinal motility. Which of these functions are physiological and which are pharmacological is not fully understood. Although the Mercodia sandwich ELISA provides significantly higher specificity of glucagon measurement than does conventional competitive RIA, it cannot provide accurate plasma glucagon values in the presence of elevated cross-reacting plasma glicentin. This occurs in patients post-pancreatectomy or bariatric surgery and in around 30% of outpatients suspected for glucose intolerance who have not had surgery. Thus, our newly developed sandwich ELISA with higher specificity and higher sensitivity than the Mercodia sandwich ELISA is needed for accurate measurements of plasma glucagon in diabetic patients. It is expected that the new sandwich ELISA will contribute to personalized medicine for diabetes by its use in clinical tests to accurately diagnose the conditions of diabetic patients in order to design better individual treatment strategies. Meanwhile, clinical trials are being conducted worldwide to apply glucagon/GLP-1 receptor dual agonists and glucagon/GLP-1/GIP receptor triagonists to the treatment of obesity, fatty liver, and diabetes. Most clinical trials have shown that both types of drugs have stronger effects on weight reduction, improving fatty liver, and glucose tolerance than do the single GLP-1 receptor agonists. Glucagon is expected to be used as a new diagnostic marker and in a new therapeutic strategy based on a true understanding of its physiological and pharmacological functions.
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Affiliation(s)
- Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma 371-8512 Japan
| | - Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma 371-8512 Japan
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Yin J, Huang Y, Wang K, Zhong Q, Liu Y, Ji Z, Liao Y, Ma Z, Bei W, Wang W. Ginseng extract improves pancreatic islet injury and promotes β-cell regeneration in T2DM mice. Front Pharmacol 2024; 15:1407200. [PMID: 38989151 PMCID: PMC11234855 DOI: 10.3389/fphar.2024.1407200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 06/03/2024] [Indexed: 07/12/2024] Open
Abstract
Introduction Panax ginseng C. A. Mey. (Araliaceae; Ginseng Radix et Rhizoma), a traditional plant commonly utilized in Eastern Asia, has demonstrated efficacy in treating neuro-damaging diseases and diabetes mellitus. However, its precise roles and mechanism in alleviating type 2 diabetes mellitus (T2DM) need further study. The objective of this study is to explore the pharmacological effects of ginseng extract and elucidate its potential mechanisms in protecting islets and promoting β-cell regeneration. Methods The T2DM mouse model was induced through streptozotocin combined with a high-fat diet. Two batches of mice were sacrificed on the 7th and 28th days following ginseng extract administration. Body weight, fasting blood glucose levels, and glucose tolerance were detected. Morphological changes in the pancreatic islets were examined via H & E staining. Levels of serum insulin, glucagon, GLP-1, and inflammatory factors were measured using ELISA. The ability of ginseng extract to promote pancreatic islet β-cell regeneration was evaluated through insulin & PCNA double immunofluorescence staining. Furthermore, the mechanism behind β-cells regeneration was explored through insulin & glucagon double immunofluorescence staining, accompanied by immunohistochemical staining and western blot analyses. Results and Discussion The present research revealed that ginseng extract alleviates symptoms of T2DM in mice, including decreased blood glucose levels and improved glucose tolerance. Serum levels of insulin, GLP-1, and IL-10 increased following the administration of ginseng extract, while levels of glucagon, TNF-α, and IL-1β decreased. Ginseng extract preserved normal islet morphology, increased nascent β-cell population, and inhibited inflammatory infiltration within the islets, moreover, it decreased α-cell proportion while increasing β-cell proportion. Mechanistically, ginseng extract might inhibit ARX and MAFB expressions, increase MAFA level to aid in α-cell to β-cell transformation, and activate AKT-FOXM1/cyclin D2 to enhance β-cell proliferation. Our study suggests that ginseng extract may be a promising therapy in treating T2DM, especially in those with islet injury.
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Affiliation(s)
- Jianying Yin
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Yuanfeng Huang
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Ke Wang
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Qin Zhong
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Yuan Liu
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Zirui Ji
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Yiwen Liao
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Zhiyuan Ma
- Baishan Institute of Science and Technology, Baishan, Jilin, China
| | - Weijian Bei
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
| | - Weixuan Wang
- Traditional Chinese Medicine Research Institute, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
- Guangdong Provincial Research Center of Integration of Traditional Chinese Medicine and Western Medicine in Metabolic Diseases, Guangdong Pharmaceutical University, Guangzhou, Guangdong, China
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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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Al-Abdulla R, Ferrero H, Boronat-Belda T, Soriano S, Quesada I, Alonso-Magdalena P. Exploring the Effects of Metabolism-Disrupting Chemicals on Pancreatic α-Cell Viability, Gene Expression and Function: A Screening Testing Approach. Int J Mol Sci 2023; 24:ijms24021044. [PMID: 36674557 PMCID: PMC9862653 DOI: 10.3390/ijms24021044] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/26/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
Humans are constantly exposed to many environmental pollutants, some of which have been largely acknowledged as key factors in the development of metabolic disorders such as diabetes and obesity. These chemicals have been classified as endocrine-disrupting chemicals (EDCs) and, more recently, since they can interfere with metabolic functions, they have been renamed as metabolism-disrupting chemicals (MDCs). MDCs are present in many consumer products, including food packaging, personal care products, plastic bottles and containers, and detergents. The scientific literature has ever-increasingly focused on insulin-releasing pancreatic β-cells as one of the main targets for MDCs. Evidence highlights that these substances may disrupt glucose homeostasis by altering pancreatic β-cell physiology. However, their potential impact on glucagon-secreting pancreatic α-cells remains poorly known despite the essential role that this cellular type plays in controlling glucose metabolism. In the present study, we have selected seven paradigmatic MDCs representing major toxic classes, including bisphenols, phthalates, perfluorinated compounds, metals, and pesticides. By using an in vitro cell-based model, the pancreatic α-cell line αTC1-9, we have explored the effects of these compounds on pancreatic α-cell viability, gene expression, and secretion. We found that cell viability was moderately affected after bisphenol-A (BPA), bisphenol-F (BPF), and perfluorooctanesulfonic acid (PFOS) exposure, although cytotoxicity was relatively low. In addition, all bisphenols, as well as di(2-ethylhexyl) phthalate (DEHP) and cadmium chloride (CdCl2), promoted a marked decreased on glucagon secretion, together with changes in the expression of glucagon and/or transcription factors involved in cell function and identity, such as Foxo1 and Arx. Overall, our results indicated that most of the selected chemicals studied caused functional alterations in pancreatic α-cells. Moreover, we revealed, for the first time, their direct effects on key molecular aspects of pancreatic α-cell biology.
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Affiliation(s)
- Ruba Al-Abdulla
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, 03202 Elche, Spain
| | - Hilda Ferrero
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, 03202 Elche, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Talía Boronat-Belda
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, 03202 Elche, Spain
| | - Sergi Soriano
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, 03202 Elche, Spain
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 Alicante, Spain
| | - Iván Quesada
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, 03202 Elche, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Paloma Alonso-Magdalena
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, 03202 Elche, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
- Correspondence:
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Yang FR, Li SY, Hu XW, Li XR, Li HJ. Identifying the Antitumor Effects of Curcumin on Lung Adenocarcinoma Using Comprehensive Bioinformatics Analysis. Drug Des Devel Ther 2022; 16:2365-2382. [PMID: 35910781 PMCID: PMC9329682 DOI: 10.2147/dddt.s371420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/16/2022] [Indexed: 11/23/2022] Open
Abstract
Background As the main component of turmeric (Curcuma longa L.), curcumin is widely used in the treatment of various diseases. Previous studies have demonstrated that curcumin has great potential as a therapeutic agent, but the lack of understanding of the functional mechanism of the drug has hindered the widespread use of the natural product. In the present study, we used comprehensive bioinformatics analysis and in vitro experiments to explore the anti-tumor mechanism of curcumin. Materials and Methods LUAD mRNA expression data were obtained from TCGA database and differentially expressed genes (DEGs) were identified using R software. Functional enrichment analysis was conducted to further clarify its biological properties and hub genes were identified by a protein–protein interaction (PPI) network analysis. Survival analysis and molecular docking were used to analyze the effectiveness of the hub genes. By an in vitro study, we evaluated whether curcumin could influence the proliferation, migration, and invasion activities of LUAD cells. Results In this study, 1783 DEGs from LUAD tissue samples compared to normal samples were evaluated. Functional enrichment analysis and the PPI network revealed the characteristics of the DEGs. We performed a topological analysis and identified 10 hub genes. Of these, six genes (INS, GCG, SST, F2, AHSG, and NPY) were identified as potentially effective biomarkers of LUAD. The molecular docking results indicated that curcumin targets in regulating lung cancer may be INS and GCG. We found that curcumin significantly inhibited the proliferation, migration, and invasion of LUAD cells and significantly decreased the expression of the INS and GCG genes. Conclusion The results of this study suggest that the therapeutic effects of curcumin on LUAD may be achieved through the intervention of INS and GCG, which may act as potential biomarkers for LUAD prevention and treatment.
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Affiliation(s)
- Fei-Ran Yang
- College of First Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China
| | - Si-Yi Li
- College of First Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China
| | - Xi-Wen Hu
- College of First Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China
| | - Xiu-Rong Li
- Department of Oncology, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China
| | - Hui-Jie Li
- Department of Oncology, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China
- Correspondence: Hui-Jie Li; Xiu-Rong Li, Department of Oncology, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jingshi Road, Jinan, Shandong, 250014, People’s Republic of China, Email ;
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Rui L, Lin JD. Reprogramming of Hepatic Metabolism and Microenvironment in Nonalcoholic Steatohepatitis. Annu Rev Nutr 2022; 42:91-113. [PMID: 35584814 PMCID: PMC10122183 DOI: 10.1146/annurev-nutr-062220-105200] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD), a spectrum of metabolic liver disease associated with obesity, ranges from relatively benign hepatic steatosis to nonalcoholic steatohepatitis (NASH). The latter is characterized by persistent liver injury, inflammation, and liver fibrosis, which collectively increase the risk for end-stage liver diseases such as cirrhosis and hepatocellular carcinoma. Recent work has shed new light on the pathophysiology of NAFLD/NASH, particularly the role of genetic, epigenetic, and dietary factors and metabolic dysfunctions in other tissues in driving excess hepatic fat accumulation and liver injury. In parallel, single-cell RNA sequencing studies have revealed unprecedented details of the molecular nature of liver cell heterogeneity, intrahepatic cross talk, and disease-associated reprogramming of the liver immune and stromal vascular microenvironment. This review covers the recent advances in these areas, the emerging concepts of NASH pathogenesis, and potential new therapeutic opportunities. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Liangyou Rui
- Department of Molecular and Integrated Physiology and Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA;
| | - Jiandie D Lin
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA;
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Honzawa N, Fujimoto K, Kobayashi M, Kohno D, Kikuchi O, Yokota-Hashimoto H, Wada E, Ikeuchi Y, Tabei Y, Dorn GW, Utsunomiya K, Nishimura R, Kitamura T. Protein Kinase C (Pkc)-δ Mediates Arginine-Induced Glucagon Secretion in Pancreatic α-Cells. Int J Mol Sci 2022; 23:4003. [PMID: 35409362 PMCID: PMC8999522 DOI: 10.3390/ijms23074003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 03/28/2022] [Accepted: 04/01/2022] [Indexed: 02/04/2023] Open
Abstract
The pathophysiology of type 2 diabetes involves insulin and glucagon. Protein kinase C (Pkc)-δ, a serine-threonine kinase, is ubiquitously expressed and involved in regulating cell death and proliferation. However, the role of Pkcδ in regulating glucagon secretion in pancreatic α-cells remains unclear. Therefore, this study aimed to elucidate the physiological role of Pkcδ in glucagon secretion from pancreatic α-cells. Glucagon secretions were investigated in Pkcδ-knockdown InR1G9 cells and pancreatic α-cell-specific Pkcδ-knockout (αPkcδKO) mice. Knockdown of Pkcδ in the glucagon-secreting cell line InR1G9 cells reduced glucagon secretion. The basic amino acid arginine enhances glucagon secretion via voltage-dependent calcium channels (VDCC). Furthermore, we showed that arginine increased Pkcδ phosphorylation at Thr505, which is critical for Pkcδ activation. Interestingly, the knockdown of Pkcδ in InR1G9 cells reduced arginine-induced glucagon secretion. Moreover, arginine-induced glucagon secretions were decreased in αPkcδKO mice and islets from αPkcδKO mice. Pkcδ is essential for arginine-induced glucagon secretion in pancreatic α-cells. Therefore, this study may contribute to the elucidation of the molecular mechanism of amino acid-induced glucagon secretion and the development of novel antidiabetic drugs targeting Pkcδ and glucagon.
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Affiliation(s)
- Norikiyo Honzawa
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo 105-8461, Japan; (N.H.); (K.U.); (R.N.)
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Kei Fujimoto
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University Daisan Hospital, 4-11-1, Izumihoncho, Komae-shi, Tokyo 201-8601, Japan
| | - Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Daisuke Kohno
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Osamu Kikuchi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Hiromi Yokota-Hashimoto
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Eri Wada
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Yuichi Ikeuchi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Yoko Tabei
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
| | - Gerald W. Dorn
- Center for Pharmacogenomics, Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA;
| | - Kazunori Utsunomiya
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo 105-8461, Japan; (N.H.); (K.U.); (R.N.)
| | - Rimei Nishimura
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo 105-8461, Japan; (N.H.); (K.U.); (R.N.)
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan; (M.K.); (D.K.); (O.K.); (H.Y.-H.); (E.W.); (Y.I.); (Y.T.)
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9
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Wada E, Kobayashi M, Kohno D, Kikuchi O, Suga T, Matsui S, Yokota-Hashimoto H, Honzawa N, Ikeuchi Y, Tsuneoka H, Hirano T, Obinata H, Sasaki T, Kitamura T. Disordered branched chain amino acid catabolism in pancreatic islets is associated with postprandial hypersecretion of glucagon in diabetic mice. J Nutr Biochem 2021; 97:108811. [PMID: 34197915 DOI: 10.1016/j.jnutbio.2021.108811] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 01/01/2023]
Abstract
Dysregulation of glucagon is associated with the pathophysiology of type 2 diabetes. We previously reported that postprandial hyperglucagonemia is more obvious than fasting hyperglucagonemia in type 2 diabetes patients. However, which nutrient stimulates glucagon secretion in the diabetic state and the underlying mechanism after nutrient intake are unclear. To answer these questions, we measured plasma glucagon levels in diabetic mice after oral administration of various nutrients. The effects of nutrients on glucagon secretion were assessed using islets isolated from diabetic mice and palmitate-treated islets. In addition, we analyzed the expression levels of branched chain amino acid (BCAA) catabolism-related enzymes and their metabolites in diabetic islets. We found that protein, but not carbohydrate or lipid, increased plasma glucagon levels in diabetic mice. Among amino acids, BCAAs, but not the other essential or nonessential amino acids, increased plasma glucagon levels. BCAAs also directly increased the intracellular calcium concentration in α cells. When BCAAs transport was suppressed by an inhibitor of system L-amino acid transporters, glucagon secretion was reduced even in the presence of BCAAs. We also found that the expression levels of BCAA catabolism-related enzymes and their metabolite contents were altered in diabetic islets and palmitate-treated islets compared to control islets, indicating disordered BCAA catabolism in diabetic islets. Furthermore, BCKDK inhibitor BT2 suppressed BCAA-induced hypersecretion of glucagon in diabetic islets and palmitate-treated islets. Taken together, postprandial hypersecretion of glucagon in the diabetic state is attributable to disordered BCAA catabolism in pancreatic islet cells.
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Affiliation(s)
- Eri Wada
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Daisuke Kohno
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Osamu Kikuchi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Takayoshi Suga
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Sho Matsui
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan; Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hiromi Yokota-Hashimoto
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Norikiyo Honzawa
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Yuichi Ikeuchi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Haruka Tsuneoka
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Touko Hirano
- Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Hideru Obinata
- Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Tsutomu Sasaki
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan; Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan.
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10
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Kobayashi M, Satoh H, Matsuo T, Kusunoki Y, Tokushima M, Watada H, Namba M, Kitamura T. Plasma glucagon levels measured by sandwich ELISA are correlated with impaired glucose tolerance in type 2 diabetes. Endocr J 2020; 67:903-922. [PMID: 32448820 DOI: 10.1507/endocrj.ej20-0079] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Glucagon dysfunction as well as insulin dysfunction is associated with the pathogenesis of type 2 diabetes (T2DM). However, it is still unclear whether the measurement of plasma glucagon levels is useful in understanding the pathophysiology of T2DM. We recently reported that sandwich ELISA provides more accurate plasma glucagon values than conventional RIA in healthy subjects. Here we used sandwich ELISA as well as RIA to assess plasma glucagon levels, comparing them in T2DM patients and healthy subjects during oral glucose (OGTT) or meal tolerance tests (MTT). We confirmed that sandwich ELISA was able to detect more significant difference between healthy subjects and T2DM patients in the fasting levels and the response dynamics of plasma glucagon than RIA. We also found significant differences in the following glucagon parameters: (1) fasting glucagon, (2) the area under the curve (AUC) of glucagon in OGTT, and (3) the change in glucagon between 0 and 30 min (ΔGlucagon0-0.5h) in OGTT or MTT. Among these, the most apparent difference was ΔGlucagon0-0.5h in MTT. When we divided T2DM patients into two groups whose ΔGlucagon0-0.5h in MTT was either below or above the maximum value in healthy subjects, the group with higher ΔGlucagon0-0.5h showed more significant impairment of glucose tolerance. These results suggest that the assessment of plasma glucagon levels by sandwich ELISA might enhance our understanding of the pathophysiology of T2DM.
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Affiliation(s)
- Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Hiroaki Satoh
- Department of Metabolism & Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Toshihiro Matsuo
- Division of Diabetes, Endocrinology and Clinical Immunology Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Yoshiki Kusunoki
- Division of Diabetes, Endocrinology and Clinical Immunology Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | | | - Hirotaka Watada
- Department of Metabolism & Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Mitsuyoshi Namba
- Division of Diabetes, Endocrinology and Clinical Immunology Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
- Takarazuka City Hospital, Takarazuka, Hyogo, Japan
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
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11
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Tellez K, Hang Y, Gu X, Chang CA, Stein RW, Kim SK. In vivo studies of glucagon secretion by human islets transplanted in mice. Nat Metab 2020; 2:547-557. [PMID: 32694729 PMCID: PMC7739959 DOI: 10.1038/s42255-020-0213-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 04/24/2020] [Indexed: 02/06/2023]
Abstract
Little is known about regulated glucagon secretion by human islet α-cells compared to insulin secretion from β-cells, despite conclusive evidence of dysfunction in both cell types in diabetes mellitus. Distinct insulins in humans and mice permit in vivo studies of human β-cell regulation after human islet transplantation in immunocompromised mice, whereas identical glucagon sequences prevent analogous in vivo measures of glucagon output from human α-cells. Here, we use CRISPR-Cas9 editing to remove glucagon codons 2-29 in immunocompromised NSG mice, preserving the production of other proglucagon-derived hormones. Glucagon knockout NSG (GKO-NSG) mice have metabolic, liver and pancreatic phenotypes associated with glucagon-signalling deficits that revert after transplantation of human islets from non-diabetic donors. Glucagon hypersecretion by transplanted islets from donors with type 2 diabetes revealed islet-intrinsic defects. We suggest that GKO-NSG mice provide an unprecedented resource to investigate human α-cell regulation in vivo.
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Affiliation(s)
- Krissie Tellez
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yan Hang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA, USA
| | - Xueying Gu
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Charles A Chang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Roland W Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Medicine (Endocrinology Division), Stanford University School of Medicine, Stanford, CA, USA.
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12
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The Long Noncoding RNA Paupar Modulates PAX6 Regulatory Activities to Promote Alpha Cell Development and Function. Cell Metab 2019; 30:1091-1106.e8. [PMID: 31607563 PMCID: PMC7205457 DOI: 10.1016/j.cmet.2019.09.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 06/05/2019] [Accepted: 09/16/2019] [Indexed: 12/19/2022]
Abstract
Many studies have highlighted the role of dysregulated glucagon secretion in the etiology of hyperglycemia and diabetes. Accordingly, understanding the mechanisms underlying pancreatic islet α cell development and function has important implications for the discovery of new therapies for diabetes. In this study, comparative transcriptome analyses between embryonic mouse pancreas and adult mouse islets identified several pancreatic lncRNAs that lie in close proximity to essential pancreatic transcription factors, including the Pax6-associated lncRNA Paupar. We demonstrate that Paupar is enriched in glucagon-producing α cells where it promotes the alternative splicing of Pax6 to an isoform required for activation of essential α cell genes. Consistently, deletion of Paupar in mice resulted in dysregulation of PAX6 α cell target genes and corresponding α cell dysfunction, including blunted glucagon secretion. These findings illustrate a distinct mechanism by which a pancreatic lncRNA can coordinate glucose homeostasis by cell-specific regulation of a broadly expressed transcription factor.
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13
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Abarkan M, Gaitan J, Lebreton F, Perrier R, Jaffredo M, Mulle C, Magnan C, Raoux M, Lang J. The glutamate receptor GluK2 contributes to the regulation of glucose homeostasis and its deterioration during aging. Mol Metab 2019; 30:152-160. [PMID: 31767166 PMCID: PMC6807305 DOI: 10.1016/j.molmet.2019.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/04/2019] [Accepted: 09/27/2019] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE Islets secrete neurotransmitters including glutamate which participate in fine regulation of islet function. The excitatory ionotropic glutamate receptor GluK2 of the kainate receptor family is widely expressed in brain and also found in islets, mainly in α and γ cells. α cells co-release glucagon and glutamate and the latter increases glucagon release via ionotropic glutamate receptors. However, neither the precise nature of the ionotropic glutamate receptor involved nor its role in glucose homeostasis is known. As isoform specific pharmacology is not available, we investigated this question in constitutive GluK2 knock-out mice (GluK2-/-) using adult and middle-aged animals to also gain insight in a potential role during aging. METHODS We compared wild-type GluK2+/+ and knock-out GluK2-/- mice using adult (14-20 weeks) and middle-aged animals (40-52 weeks). Glucose (oral OGTT and intraperitoneal IPGTT) and insulin tolerance as well as pyruvate challenge tests were performed according to standard procedures. Parasympathetic activity, which stimulates hormones secretion, was measured by electrophysiology in vivo. Isolated islets were used in vitro to determine islet β-cell electrical activity on multi-electrode arrays and dynamic secretion of insulin as well as glucagon was determined by ELISA. RESULTS Adult GluK2-/- mice exhibit an improved glucose tolerance (OGTT and IPGTT), and this was also apparent in middle-aged mice, whereas the outcome of pyruvate challenge was slightly improved only in middle-aged GluK2-/- mice. Similarly, insulin sensitivity was markedly enhanced in middle-aged GluK2-/- animals. Basal and glucose-induced insulin secretion in vivo was slightly lower in GluK2-/- mice, whereas fasting glucagonemia was strongly reduced. In vivo recordings of parasympathetic activity showed an increase in basal activity in GluK2-/- mice which represents most likely an adaptive mechanism to counteract hypoglucagonemia rather than altered neuronal mechanism. In vitro recording demonstrated an improvement of glucose-induced electrical activity of β-cells in islets obtained from GluK2-/- mice at both ages. Finally, glucose-induced insulin secretion in vitro was increased in GluK2-/- islets, whereas glucagon secretion at 2 mmol/l of glucose was considerably reduced. CONCLUSIONS These observations indicate a general role for kainate receptors in glucose homeostasis and specifically suggest a negative effect of GluK2 on glucose homeostasis and preservation of islet function during aging. Our observations raise the possibility that blockade of GluK2 may provide benefits in glucose homeostasis especially during aging.
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Affiliation(s)
- Myriam Abarkan
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Julien Gaitan
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Fanny Lebreton
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Romain Perrier
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Manon Jaffredo
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Université de Bordeaux, Bordeaux, France
| | - Christophe Magnan
- Unité de Biologie Fonctionnelle et Adaptative, UMR 8251, CNRS, Université de Paris, Paris, France
| | - Matthieu Raoux
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France
| | - Jochen Lang
- Chimie et Biologie des Membranes et Nano-objets, UMR CNRS 5248, Université de Bordeaux, Pessac, France.
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14
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Cell Autonomous Dysfunction and Insulin Resistance in Pancreatic α Cells. Int J Mol Sci 2019; 20:ijms20153699. [PMID: 31357734 PMCID: PMC6695724 DOI: 10.3390/ijms20153699] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 12/23/2022] Open
Abstract
To date, type 2 diabetes is considered to be a "bi-hormonal disorder" rather than an "insulin-centric disorder," suggesting that glucagon is as important as insulin. Although glucagon increases hepatic glucose production and blood glucose levels, paradoxical glucagon hypersecretion is observed in diabetes. Recently, insulin resistance in pancreatic α cells has been proposed to be associated with glucagon dysregulation. Moreover, cell autonomous dysfunction of α cells is involved in the etiology of diabetes. In this review, we summarize the current knowledge about the physiological and pathological roles of glucagon.
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15
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Abstract
PURPOSE OF REVIEW Pancreatic β-cells play a critical role in whole-body glucose homeostasis by regulating the release of insulin in response to minute by minute alterations in metabolic demand. As such, β-cells are staunchly resilient but there are circumstances where they can become functionally compromised or physically lost due to pathophysiological changes which culminate in overt hyperglycemia and diabetes. RECENT FINDINGS In humans, β-cell mass appears to be largely defined in the postnatal period and this early replicative and generative phase is followed by a refractory state which persists throughout life. Despite this, efforts to identify physiological and pharmacological factors which might re-initiate β-cell replication (or cause the replenishment of β-cells by neogenesis or transdifferentiation) are beginning to bear fruit. Controlled manipulation of β-cell mass in humans still represents a holy grail for therapeutic intervention in diabetes, but progress is being made which may lead to ultimate success.
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Affiliation(s)
- Giorgio Basile
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute, Boston, MA 02215, USA
| | - Rohit N. Kulkarni
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute, Boston, MA 02215, USA
| | - Noel G. Morgan
- Institute of Biomedical & Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK
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16
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Li X, Jia L, Chen X, Dong Y, Ren X, Dong Y, Chen Y, Xie L, Liu M, Shiota C, Gittes GK, Rui L, Chen Z. Islet α-cell Inflammation Induced By NF-κB inducing kinase (NIK) Leads to Hypoglycemia, Pancreatitis, Growth Retardation, and Postnatal Death in Mice. Theranostics 2018; 8:5960-5971. [PMID: 30613274 PMCID: PMC6299425 DOI: 10.7150/thno.28960] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/04/2018] [Indexed: 11/29/2022] Open
Abstract
Islet α-cell dysfunction has been shown to contribute to type 2 diabetes; however, whether islet α-cell inflammation is involved in the occurrence of pancreatitis is largely unknown. The aims of this study were to investigate how NF-κB inducing kinase (NIK) regulates pancreatic α-cell function, both in vitro and in vivo, and to assess how islet α-cell inflammation induced by NIK affects the development of pancreatitis. Methods: We utilized adenovirus-mediated NIK overexpression, ELISA, qPCR, RNA-seq, and Western blot analyses to study the role of NIK in islet α cells in vitro. Islet α-cell-specific NIK overexpressing (α-NIK-OE) mice were generated, and pancreatic α/β-cell function and the occurrence of pancreatitis in these mice were assessed via ELISA, qPCR, and immunohistochemical analyses. Results: The LTβR/noncanonical NF-κB signaling pathway is present in islet α cells. Overexpression of NIK in αTC1-6 cells induces inflammation and cell death, contributing to a decrease in the expression and secretion of glucagon. Additionally, α-cell specific overexpression of NIK (α-NIK-OE) results in α-cell death, lower serum glucagon levels, and hypoglycemia in mice. Strikingly, α-NIK-OE mice also display a reduced β-cell mass, growth retardation, pancreatitis, and postnatal death. Conclusions: Islet α-cell specific overexpression of NIK results in islet α-cell dysfunction and causes islet β-cell death and pancreatitis, which are most likely due to paracrine secretion of cytokines and chemokines from islet α cells, thus leading to hypoglycemia, growth retardation, and postnatal death in mice.
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Affiliation(s)
- Xinzhi Li
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
- HIT Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150080, China
| | - Linna Jia
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Xiaoyue Chen
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Ying Dong
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Xiaomeng Ren
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Yuefan Dong
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Ying Chen
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Liwei Xie
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou 510070, China
| | - Ming Liu
- Department of endocrinology and metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Chiyo Shiota
- Division of Pediatric Surgery, Department of Surgery, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - George K. Gittes
- Division of Pediatric Surgery, Department of Surgery, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Liangyou Rui
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Zheng Chen
- HIT Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150080, China
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17
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SGLT1 in pancreatic α cells regulates glucagon secretion in mice, possibly explaining the distinct effects of SGLT2 inhibitors on plasma glucagon levels. Mol Metab 2018; 19:1-12. [PMID: 30416006 PMCID: PMC6323192 DOI: 10.1016/j.molmet.2018.10.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/19/2018] [Accepted: 10/23/2018] [Indexed: 01/23/2023] Open
Abstract
Objectives It is controversial whether sodium glucose transporter (SGLT) 2 inhibitors increase glucagon secretion via direct inhibition of SGLT2 in pancreatic α cells. The role of SGLT1 in α cells is also unclear. We aimed to elucidate these points that are important not only for basic research but also for clinical insight. Methods Plasma glucagon levels were assessed in the high-fat, high-sucrose diet (HFHSD) fed C57BL/6J mice treated with dapagliflozin or canagliflozin. RT-PCR, RNA sequence, and immunohistochemistry were conducted to test the expression of SGLT1 and SGLT2 in α cells. We also used αTC1 cells and mouse islets to investigate the molecular mechanism by which SGLT1 modulates glucagon secretion. Results Dapagliflozin, but not canagliflozin, increased plasma glucagon levels in HFHSD fed mice. SGLT1 and glucose transporter 1 (GLUT1), but not SGLT2, were expressed in αTC1 cells, mouse islets and human islets. A glucose clamp study revealed that the plasma glucagon increase associated with dapagliflozin could be explained as a response to acute declines in blood glucose. Canagliflozin suppressed glucagon secretion by inhibiting SGLT1 in α cells; consequently, plasma glucagon did not increase with canagliflozin, even though blood glucose declined. SGLT1 effect on glucagon secretion depended on glucose transport, but not glucose metabolism. Islets from HFHSD and db/db mice displayed higher SGLT1 mRNA levels and lower GLUT1 mRNA levels than the islets from control mice. These expression levels were associated with higher glucagon secretion. Furthermore, SGLT1 inhibitor and siRNA against SGLT1 suppressed glucagon secretion in isolated islets. Conclusions These data suggested that a novel mechanism regulated glucagon secretion through SGLT1 in α cells. This finding possibly explained the distinct effects of dapagliflozin and canagliflozin on plasma glucagon levels in mice. SGLT1, but not SGLT2, is expressed in αTC1 cells, mouse islets and human islets. SGLT2 inhibitor dapagliflozin increases plasma glucagon in diabetic mice. SGLT2/low potency SGLT1 inhibitor canagliflozin does not increase plasma glucagon. Canagliflozin suppresses glucagon secretion by inhibiting SGLT1 in α cells. Higher expression of SGLT1 in islets is associated with higher glucagon secretion.
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18
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Zhang Y, Thai K, Jin T, Woo M, Gilbert RE. SIRT1 activation attenuates α cell hyperplasia, hyperglucagonaemia and hyperglycaemia in STZ-diabetic mice. Sci Rep 2018; 8:13972. [PMID: 30228292 PMCID: PMC6143559 DOI: 10.1038/s41598-018-32351-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 09/04/2018] [Indexed: 12/19/2022] Open
Abstract
The NAD+-dependent lysine deacetylase, Sirtuin 1 (SIRT1), plays a central role in metabolic regulation. With type 1 diabetes a disease that is characterised by metabolic dysregulation, we sought to assess the impact of SIRT1 activation in experimental, streptozotocin (STZ)-induced diabetes. CD1 mice with and without STZ-induced diabetes were randomized to receive the SIRT1 activating compound, SRT3025, or vehicle over 20 weeks. Vehicle treated STZ-CD1 mice developed severe hyperglycaemia with near-absent circulating insulin and widespread beta cell loss in association with hyperglucagonaemia and expanded islet alpha cell mass. Without affecting ß-cell mass or circulating insulin, diabetic mice that received SRT3025 had substantially improved glycaemic control with greatly reduced islet α cell mass and lower plasma glucagon concentrations. Consistent with reduced glucagon abundance, the diabetes-associated overexpression of key gluconeogenic enzymes, glucose-6-phosphatase and PEPCK were also lowered by SRT3025. Incubating cultured α cells with SRT3025 diminished their glucagon secretion and proliferative activity in association with a reduction in the α cell associated transcription factor, Aristaless Related Homeobox (Arx). By reducing the paradoxical increase in glucagon, SIRT1 activation may offer a new, α-cell centric approach to the treatment of type 1 diabetes.
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Affiliation(s)
- Yanling Zhang
- St. Michael's Hospital, Keenan Research Centre, Li Ka Shing Knowledge Institute, Toronto, M5B 1W8, Canada
| | - Kerri Thai
- St. Michael's Hospital, Keenan Research Centre, Li Ka Shing Knowledge Institute, Toronto, M5B 1W8, Canada
| | - Tianru Jin
- Toronto General Hospital Research Institute (TGHRI), Toronto, ON, M5G 2C4, Canada
| | - Minna Woo
- Toronto General Hospital Research Institute (TGHRI), Toronto, ON, M5G 2C4, Canada
| | - Richard E Gilbert
- St. Michael's Hospital, Keenan Research Centre, Li Ka Shing Knowledge Institute, Toronto, M5B 1W8, Canada.
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19
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Yang SQ, Chen YD, Li H, Hui X, Gao WY. Geniposide and Gentiopicroside Suppress Hepatic Gluconeogenesis via Regulation of AKT-FOXO1 Pathway. Arch Med Res 2018; 49:314-322. [DOI: 10.1016/j.arcmed.2018.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 09/26/2018] [Accepted: 10/15/2018] [Indexed: 10/27/2022]
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20
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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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21
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Gao Z, Wang B, Gong X, Yao C, Ren D, Shao L, Pang Y, Liu J. Effect of gastric bypass combined with ileal transportation on type 2 diabetes mellitus. Exp Ther Med 2018; 15:4571-4577. [PMID: 29725390 DOI: 10.3892/etm.2018.5928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 12/08/2017] [Indexed: 01/14/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a chronic progressive disease, which manifests as an endocrine disorder. Among the different methods of surgery available to treat patients with T2DM, Roux-en-Y gastric bypass (RYGBP) and ileal transposition (IT) are the most commonly performed. The aim of the present study was to investigate the effects of RYGBP combined with IT on rats with T2DM. A total of 8 healthy male rats were used as a control group and 40 GK rats were randomly divided into 5 groups: A diabetes mellitus (DM) group, a sham operative group (SO), a RYGBP group, an IT group and a RYGBP+IT group. The results demonstrated that fasting blood glucose, triglyceride, total cholesterol and gastric inhibitory polypeptide levels in all treatment groups were significantly lower than those of the SO and DM groups. Furthermore, levels TC and TG in the RYGBP+IT group were significantly lower than in the RYGBP and IT groups. Levels of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase mRNA and IRS-2 protein in all treatment groups were also significantly lower than those of the SO group; and they were significantly lower in the RYGBP+IT group compared with the RYGBP and IT groups. The expression of phosphorylated Akt in the treatment groups was significantly higher than the SO group and was significantly higher in the RYGBP+IT group compared with the RYGBP and IT groups. These results indicate that RYGBP and IT surgical treatment can induce T2DM remission by mediating the expression of insulin-related factors to reverse insulin resistance. The current study also indicated that the effect of RYGBP combined with IT may be developed as a novel first-line method of treating T2DM.
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Affiliation(s)
- Zhaoxia Gao
- Department of General Surgery, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Bin Wang
- Department of Ear-Nose-Throat, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Xiaojun Gong
- Department of General Surgery, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Chun Yao
- Department of Endocrinology, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Defa Ren
- Department of General Surgery, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Liwei Shao
- Department of General Surgery, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Yan Pang
- Department of Clinical Laboratory, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Jinxiu Liu
- Department of General Surgery, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
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22
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Yagi T, Kubota E, Koyama H, Tanaka T, Kataoka H, Imaeda K, Joh T. Glucagon promotes colon cancer cell growth via regulating AMPK and MAPK pathways. Oncotarget 2018. [PMID: 29535833 PMCID: PMC5828215 DOI: 10.18632/oncotarget.24367] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cancer is one of the major causes of death in diabetic patients, and an association between antidiabetic drugs and cancer risk has been reported. Such evidence implies a strong connection between diabetes and cancer. Recently, glucagon has been recognized as a pivotal factor implicated in the pathophysiology of diabetes. Glucagon acts through binding to its receptor, glucagon receptor (GCGR), and cross-talk between GCGR-mediated signals and signaling pathways that regulate cancer cell fate has been unveiled. In the current study, expression of GCGR in colon cancer cell lines and colon cancer tissue obtained from patients was demonstrated. Glucagon significantly promoted colon cancer cell growth, and GCGR knockdown with small interfering RNA attenuated the proliferation-promoting effect of glucagon on colon cancer cells. Molecular assays showed that glucagon acted as an activator of cancer cell growth through deactivation of AMPK and activation of MAPK in a GCGR-dependent manner. Moreover, a stable GCGR knockdown mouse colon cancer cell line, CMT93, grew significantly slower than control in a syngeneic mouse model of type 2 diabetes with glycemia and hyperglucagonemia. The present observations provide experimental evidence that hyperglucagonemia in type 2 diabetes promotes colon cancer progression via GCGR-mediated regulation of AMPK and MAPK pathways.
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Affiliation(s)
- Takashi Yagi
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Eiji Kubota
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Hiroyuki Koyama
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Tomohiro Tanaka
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Hiromi Kataoka
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Kenro Imaeda
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Takashi Joh
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
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23
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Murai N, Ohtaki H, Watanabe J, Xu Z, Sasaki S, Yagura K, Shioda S, Nagasaka S, Honda K, Izumizaki M. Intrapancreatic injection of human bone marrow-derived mesenchymal stem/stromal cells alleviates hyperglycemia and modulates the macrophage state in streptozotocin-induced type 1 diabetic mice. PLoS One 2017; 12:e0186637. [PMID: 29073149 PMCID: PMC5657972 DOI: 10.1371/journal.pone.0186637] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 10/04/2017] [Indexed: 12/11/2022] Open
Abstract
Type 1 diabetes mellitus is a progressive disease caused by the destruction of pancreatic β-cells, resulting in insulin dependency and hyperglycemia. While transplanted bone marrow-derived mesenchymal stem/stromal cells (BMMSCs) have been explored as an alternative therapeutic approach for diseases, the choice of delivery route may be a critical factor determining their sustainability. This study evaluated the effects of intrapancreatic and intravenous injection of human BMMSCs (hBMMSCs) in streptozotocin (STZ)-induced type 1 diabetic mouse model. C57/BL6 mice were intraperitoneally injected with 115 mg/kg STZ on day 0. hBMMSCs (1 × 106 cells) or vehicle were injected into the pancreas or jugular vein on day 7. Intrapancreatic, but not intravenous, hBMMSC injection significantly reduced blood glucose levels on day 28 compared with vehicle injection by the same route. This glucose-lowering effect was not induced by intrapancreatic injection of human fibroblasts as the xenograft control. Intrapancreatically injected fluorescence-labeled hBMMSCs were observed in the intra- and extra-lobular spaces of the pancreas, and intravenously injected cells were in the lung region, although the number of cells mostly decreased within 2 weeks of injection. For hBMMSCs injected twice into the pancreatic region on days 7 and 28, the injected mice had further reduced blood glucose to borderline diabetic levels on day 56. Animals injected with hBMMSCs twice exhibited increases in the plasma insulin level, number and size of islets, insulin-positive proportion of the total pancreas area, and intensity of insulin staining compared with vehicle-injected animals. We found a decrease of Iba1-positive cells in islets and an increase of CD206-positive cells in both the endocrine and exocrine pancreas. The hBMMSC injection also reduced the number of CD40-positive cells merged with glucagon immunoreactions in the islets. These results suggest that intrapancreatic injection may be a better delivery route of hBMMSCs for the treatment of type 1 diabetes mellitus.
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Affiliation(s)
- Norimitsu Murai
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
- Division of Diabetes, Metabolism and Endocrinology, Showa University Fujigaoka Hospital, Yokohama, Japan
| | - Hirokazu Ohtaki
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Jun Watanabe
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
- Center for Biotechnology, Showa University, Tokyo, Japan
| | - Zhifang Xu
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Shun Sasaki
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Kazumichi Yagura
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Seiji Shioda
- Peptide Drug Innovation, Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo, Japan
| | - Shoichiro Nagasaka
- Division of Diabetes, Metabolism and Endocrinology, Showa University Fujigaoka Hospital, Yokohama, Japan
| | - Kazuho Honda
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Masahiko Izumizaki
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan
- * E-mail:
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24
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Yin Y, de Waal PW, He Y, Zhao LH, Yang D, Cai X, Jiang Y, Melcher K, Wang MW, Xu HE. Rearrangement of a polar core provides a conserved mechanism for constitutive activation of class B G protein-coupled receptors. J Biol Chem 2017; 292:9865-9881. [PMID: 28356352 DOI: 10.1074/jbc.m117.782987] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/20/2017] [Indexed: 11/06/2022] Open
Abstract
The glucagon receptor (GCGR) belongs to the secretin-like (class B) family of G protein-coupled receptors (GPCRs) and is activated by the peptide hormone glucagon. The structures of an activated class B GPCR have remained unsolved, preventing a mechanistic understanding of how these receptors are activated. Using a combination of structural modeling and mutagenesis studies, we present here two modes of ligand-independent activation of GCGR. First, we identified a GCGR-specific hydrophobic lock comprising Met-338 and Phe-345 within the IC3 loop and transmembrane helix 6 (TM6) and found that this lock stabilizes the TM6 helix in the inactive conformation. Disruption of this hydrophobic lock led to constitutive G protein and arrestin signaling. Second, we discovered a polar core comprising conserved residues in TM2, TM3, TM6, and TM7, and mutations that disrupt this polar core led to constitutive GCGR activity. On the basis of these results, we propose a mechanistic model of GCGR activation in which TM6 is held in an inactive conformation by the conserved polar core and the hydrophobic lock. Mutations that disrupt these inhibitory elements allow TM6 to swing outward to adopt an active TM6 conformation similar to that of the canonical β2-adrenergic receptor complexed with G protein and to that of rhodopsin complexed with arrestin. Importantly, mutations in the corresponding polar core of several other members of class B GPCRs, including PTH1R, PAC1R, VIP1R, and CRFR1, also induce constitutive G protein signaling, suggesting that the rearrangement of the polar core is a conserved mechanism for class B GPCR activation.
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Affiliation(s)
- Yanting Yin
- From the Van Andel Research Institute - Shanghai Institute of Materia Medica (VARI-SIMM) Center, Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China.,the Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, Grand Rapids, Michigan 49503.,the University of Chinese Academy of Sciences, Number 19A Yuquan Road, Beijing 100049, China
| | - Parker W de Waal
- the Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Yuanzheng He
- the Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Li-Hua Zhao
- From the Van Andel Research Institute - Shanghai Institute of Materia Medica (VARI-SIMM) Center, Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Dehua Yang
- The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China, and
| | - Xiaoqing Cai
- The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China, and
| | - Yi Jiang
- From the Van Andel Research Institute - Shanghai Institute of Materia Medica (VARI-SIMM) Center, Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Karsten Melcher
- the Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Ming-Wei Wang
- The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China, and .,the School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China
| | - H Eric Xu
- From the Van Andel Research Institute - Shanghai Institute of Materia Medica (VARI-SIMM) Center, Center for Structure and Function of Drug Targets, The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China, .,the Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, Grand Rapids, Michigan 49503.,the University of Chinese Academy of Sciences, Number 19A Yuquan Road, Beijing 100049, China
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25
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Benthuysen JR, Carrano AC, Sander M. Advances in β cell replacement and regeneration strategies for treating diabetes. J Clin Invest 2016; 126:3651-3660. [PMID: 27694741 DOI: 10.1172/jci87439] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In the past decade, new approaches have been explored that are aimed at restoring functional β cell mass as a treatment strategy for diabetes. The two most intensely pursued strategies are β cell replacement through conversion of other cell types and β cell regeneration by enhancement of β cell replication. The approach closest to clinical implementation is the replacement of β cells with human pluripotent stem cell-derived (hPSC-derived) cells, which are currently under investigation in a clinical trial to assess their safety in humans. In addition, there has been success in reprogramming developmentally related cell types into β cells. Reprogramming approaches could find therapeutic applications by inducing β cell conversion in vivo or by reprogramming cells ex vivo followed by implantation. Finally, recent studies have revealed novel pharmacologic targets for stimulating β cell replication. Manipulating these targets or the pathways they regulate could be a strategy for promoting the expansion of residual β cells in diabetic patients. Here, we provide an overview of progress made toward β cell replacement and regeneration and discuss promises and challenges for clinical implementation of these strategies.
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26
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Vieira A, Courtney M, Druelle N, Avolio F, Napolitano T, Hadzic B, Navarro-Sanz S, Ben-Othman N, Collombat P. β-Cell replacement as a treatment for type 1 diabetes: an overview of possible cell sources and current axes of research. Diabetes Obes Metab 2016; 18 Suppl 1:137-43. [PMID: 27615143 DOI: 10.1111/dom.12721] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 04/27/2016] [Indexed: 01/09/2023]
Abstract
To efficiently treat type 1 diabetes, exogenous insulin injections currently represent the main approach to counter chronic hyperglycaemia. Unfortunately, such a therapeutic approach does not allow for perfectly maintained glucose homeostasis and, in time, cardiovascular complications may arise. Therefore, seeking alternative/improved treatments has become a major health concern as an increasing proportion of type 2 diabetes patients also require insulin supplementation. Towards this goal, numerous laboratories have focused their research on β-cell replacement therapies. Herein, we will review the current state of this research area and describe the cell sources that could potentially be used to replenish the depleted β-cell mass in diabetic patients.
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Affiliation(s)
- A Vieira
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - M Courtney
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - N Druelle
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - F Avolio
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - T Napolitano
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - B Hadzic
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | | | - N Ben-Othman
- Université Côte d'Azur, CNRS, Inserm, iBV, France
| | - P Collombat
- Université Côte d'Azur, CNRS, Inserm, iBV, France.
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27
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Gao Z, Zhang L, Xie W, Wang S, Bao X, Guo Y, Zhang H, Hu Q, Chen Y, Wang Z, Xue M, Jin G. Male Men1 heterozygous mice exhibit fasting hyperglycemia in the early stage of MEN1. J Endocrinol 2016; 230:347-55. [PMID: 27432891 DOI: 10.1530/joe-16-0090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 07/18/2016] [Indexed: 01/29/2023]
Abstract
Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited syndrome characterized by multiple tumors in the parathyroid glands, endocrine pancreas and anterior pituitary. Recent clinical studies have revealed a strong association between MEN1 syndrome and the risk of developing diabetes mellitus; however, the underlying mechanisms remain unknown. In this study, heterozygous Men1 knockout (Men1(+/-)) mice were used as MEN1 models to investigate MEN1-associated glucose metabolic phenotypes and mechanisms. Heterozygous deficiency of Men1 in 12-month-old male mice induced fasting hyperglycemia, along with increased serum insulin levels. However, male Men1(+/-) mice did not show insulin resistance, as evidenced by Akt activation in hepatic tissues and an insulin tolerance test. Increased glucose levels following pyruvate challenge and expression of key gluconeogenic genes suggested increased hepatic glucose output in the male Men1(+/-) mice. This effect could be partly due to higher basal serum glucagon levels, which resulted from pancreatic islet cell proliferation induced by heterozygous loss of Men1 Taken together, our results indicate that fasted male Men1(+/-) mice, in the early stage of development of MEN1, display glucose metabolic disorders. These disorders are caused not by direct induction of insulin resistance, but via increased glucagon secretion and the consequent stimulation of hepatic glucose production.
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Affiliation(s)
- Zhongxiuzi Gao
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Li Zhang
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Wenting Xie
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Siqi Wang
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Xiaorui Bao
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Yuli Guo
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Houjian Zhang
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Qingzhong Hu
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Yi Chen
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Zeen Wang
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Maoqiang Xue
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
| | - Guanghui Jin
- Department of Basic Medical SciencesMedical College, Xiamen University, Xiamen, China
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28
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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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29
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Kazda CM, Ding Y, Kelly RP, Garhyan P, Shi C, Lim CN, Fu H, Watson DE, Lewin AJ, Landschulz WH, Deeg MA, Moller DE, Hardy TA. Evaluation of Efficacy and Safety of the Glucagon Receptor Antagonist LY2409021 in Patients With Type 2 Diabetes: 12- and 24-Week Phase 2 Studies. Diabetes Care 2016; 39:1241-9. [PMID: 26681715 DOI: 10.2337/dc15-1643] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 03/30/2016] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Type 2 diabetes pathophysiology is characterized by dysregulated glucagon secretion. LY2409021, a potent, selective small-molecule glucagon receptor antagonist that lowers glucose was evaluated for efficacy and safety in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS The efficacy (HbA1c and glucose) and safety (serum aminotransferase) of once-daily oral administration of LY2409021 was assessed in two double-blind studies. Phase 2a study patients were randomized to 10, 30, or 60 mg of LY2409021 or placebo for 12 weeks. Phase 2b study patients were randomized to 2.5, 10, or 20 mg LY2409021 or placebo for 24 weeks. RESULTS LY2409021 produced reductions in HbA1c that were significantly different from placebo over both 12 and 24 weeks. After 12 weeks, least squares (LS) mean change from baseline in HbA1c was -0.83% (10 mg), -0.65% (30 mg), and -0.66% (60 mg) (all P < 0.05) vs. placebo, 0.11%. After 24 weeks, LS mean change from baseline in HbA1c was -0.45% (2.5 mg), -0.78% (10 mg, P < 0.05), -0.92% (20 mg, P < 0.05), and -0.15% with placebo. Increases in serum aminotransferase, fasting glucagon, and total fasting glucagon-like peptide-1 (GLP-1) were observed; levels returned to baseline after drug washout. Fasting glucose was also lowered with LY2409021 at doses associated with only modest increases in aminotransferases (mean increase in alanine aminotransferase [ALT] ≤10 units/L). The incidence of hypoglycemia in the LY2409021 groups was not statistically different from placebo. CONCLUSIONS In patients with type 2 diabetes, glucagon receptor antagonist treatment significantly lowered HbA1c and glucose levels with good overall tolerability and a low risk for hypoglycemia. Modest, reversible increases in serum aminotransferases were observed.
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Affiliation(s)
| | - Ying Ding
- Eli Lilly and Company, Indianapolis, IN
| | - Ronan P Kelly
- Lilly-NUS Centre for Clinical Pharmacology, Singapore
| | | | | | | | - Haoda Fu
- Eli Lilly and Company, Indianapolis, IN
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30
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Iida A, Seino Y, Fukami A, Maekawa R, Yabe D, Shimizu S, Kinoshita K, Takagi Y, Izumoto T, Ogata H, Ishikawa K, Ozaki N, Tsunekawa S, Hamada Y, Oiso Y, Arima H, Hayashi Y. Endogenous GIP ameliorates impairment of insulin secretion in proglucagon-deficient mice under moderate beta cell damage induced by streptozotocin. Diabetologia 2016; 59:1533-1541. [PMID: 27053237 PMCID: PMC4901104 DOI: 10.1007/s00125-016-3935-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/02/2016] [Indexed: 01/06/2023]
Abstract
AIMS/HYPOTHESIS The action of incretin hormones including glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) is potentiated in animal models defective in glucagon action. It has been reported that such animal models maintain normoglycaemia under streptozotocin (STZ)-induced beta cell damage. However, the role of GIP in regulation of glucose metabolism under a combination of glucagon deficiency and STZ-induced beta cell damage has not been fully explored. METHODS In this study, we investigated glucose metabolism in mice deficient in proglucagon-derived peptides (PGDPs)-namely glucagon gene knockout (GcgKO) mice-administered with STZ. Single high-dose STZ (200 mg/kg, hSTZ) or moderate-dose STZ for five consecutive days (50 mg/kg × 5, mSTZ) was administered to GcgKO mice. The contribution of GIP to glucose metabolism in GcgKO mice was also investigated by experiments employing dipeptidyl peptidase IV (DPP4) inhibitor (DPP4i) or Gcg-Gipr double knockout (DKO) mice. RESULTS GcgKO mice developed severe diabetes by hSTZ administration despite the absence of glucagon. Administration of mSTZ decreased pancreatic insulin content to 18.8 ± 3.4 (%) in GcgKO mice, but ad libitum-fed blood glucose levels did not significantly increase. Glucose-induced insulin secretion was marginally impaired in mSTZ-treated GcgKO mice but was abolished in mSTZ-treated DKO mice. Although GcgKO mice lack GLP-1, treatment with DPP4i potentiated glucose-induced insulin secretion and ameliorated glucose intolerance in mSTZ-treated GcgKO mice, but did not increase beta cell area or significantly reduce apoptotic cells in islets. CONCLUSIONS/INTERPRETATION These results indicate that GIP has the potential to ameliorate glucose intolerance even under STZ-induced beta cell damage by increasing insulin secretion rather than by promoting beta cell survival.
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Affiliation(s)
- Atsushi Iida
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yusuke Seino
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan.
- Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Ayako Fukami
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Ryuya Maekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Daisuke Yabe
- Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute, Kobe, Japan
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinobu Shimizu
- Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute, Kobe, Japan
| | - Keita Kinoshita
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan
| | - Yusuke Takagi
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan
| | - Takako Izumoto
- Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetada Ogata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Kota Ishikawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Nobuaki Ozaki
- Research Center of Health, Physical Fitness and Sports, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Shin Tsunekawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yoji Hamada
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
- Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yutaka Oiso
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 4668550, Japan
| | - Yoshitaka Hayashi
- Department of Genetics, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 4648601, Japan.
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Marsh ED, Nasrallah MP, Walsh C, Murray KA, Nicole Sunnen C, McCoy A, Golden JA. Developmental interneuron subtype deficits after targeted loss of Arx. BMC Neurosci 2016; 17:35. [PMID: 27287386 PMCID: PMC4902966 DOI: 10.1186/s12868-016-0265-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 06/03/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aristaless-related homeobox (ARX) is a paired-like homeodomain transcription factor that functions primarily as a transcriptional repressor and has been implicated in neocortical interneuron specification and migration. Given the role interneurons appear to play in numerous human conditions including those associated with ARX mutations, it is essential to understand the consequences of mutations in this gene on neocortical interneurons. Previous studies have examined the effect of germline loss of Arx, or targeted mutations in Arx, on interneuron development. We now present the effect of conditional loss of Arx on interneuron development. RESULTS To further elucidate the role of Arx in forebrain development we performed a series of anatomical and developmental studies to determine the effect of conditional loss of Arx specifically from developing interneurons in the neocortex and hippocampus. Analysis and cell counts were performed from mouse brains using immunohistochemical and in situ hybridization assays at 4 times points across development. Our data indicate that early in development, instead of a loss of ventral precursors, there is a shift of these precursors to more ventral locations, a deficit that persists in the adult nervous system. The result of this developmental shift is a reduced number of interneurons (all subtypes) at early postnatal and later time periods. In addition, we find that X inactivation is stochastic, and occurs at the level of the neural progenitors. CONCLUSION These data provide further support that the role of Arx in interneuron development is to direct appropriate migration of ventral neuronal precursors into the dorsal cortex and that the loss of Arx results in a failure of interneurons to reach the cortex and thus a deficiency in interneurons.
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Affiliation(s)
- Eric D Marsh
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA. .,Division of Child Neurology, Children's Hospital of Philadelphia, Room 502E, Abramson Research Building, 3615 Civic Center Boulevard, Philadelphia, PA, 19014, USA. .,Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
| | - MacLean Pancoast Nasrallah
- Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pathology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Caroline Walsh
- Division of Child Neurology, Children's Hospital of Philadelphia, Room 502E, Abramson Research Building, 3615 Civic Center Boulevard, Philadelphia, PA, 19014, USA
| | - Kaitlin A Murray
- Division of Child Neurology, Children's Hospital of Philadelphia, Room 502E, Abramson Research Building, 3615 Civic Center Boulevard, Philadelphia, PA, 19014, USA
| | - C Nicole Sunnen
- Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Almedia McCoy
- Division of Child Neurology, Children's Hospital of Philadelphia, Room 502E, Abramson Research Building, 3615 Civic Center Boulevard, Philadelphia, PA, 19014, USA
| | - Jeffrey A Golden
- Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, PA, USA. .,Department of Pathology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA. .,Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA, 02115, USA.
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32
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Affiliation(s)
- Changhong Li
- Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Joseph A Baur
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Kusminski CM, Chen S, Ye R, Sun K, Wang QA, Spurgin SB, Sanders PE, Brozinick JT, Geldenhuys WJ, Li WH, Unger RH, Scherer PE. MitoNEET-Parkin Effects in Pancreatic α- and β-Cells, Cellular Survival, and Intrainsular Cross Talk. Diabetes 2016; 65:1534-55. [PMID: 26895793 PMCID: PMC5310214 DOI: 10.2337/db15-1323] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/06/2016] [Indexed: 12/16/2022]
Abstract
Mitochondrial metabolism plays an integral role in glucose-stimulated insulin secretion (GSIS) in β-cells. In addition, the diabetogenic role of glucagon released from α-cells plays a major role in the etiology of both type 1 and type 2 diabetes because unopposed hyperglucagonemia is a pertinent contributor to diabetic hyperglycemia. Titrating expression levels of the mitochondrial protein mitoNEET is a powerful approach to fine-tune mitochondrial capacity of cells. Mechanistically, β-cell-specific mitoNEET induction causes hyperglycemia and glucose intolerance due to activation of a Parkin-dependent mitophagic pathway, leading to the formation of vacuoles and uniquely structured mitophagosomes. Induction of mitoNEET in α-cells leads to fasting-induced hypoglycemia and hypersecretion of insulin during GSIS. MitoNEET-challenged α-cells exert potent antiapoptotic effects on β-cells and prevent cellular dysfunction associated with mitoNEET overexpression in β-cells. These observations identify that reduced mitochondrial function in α-cells exerts potently protective effects on β-cells, preserving β-cell viability and mass.
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Affiliation(s)
- Christine M Kusminski
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Shiuhwei Chen
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Risheng Ye
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Kai Sun
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Qiong A Wang
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Stephen B Spurgin
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Phillip E Sanders
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN
| | - Joseph T Brozinick
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN
| | - Werner J Geldenhuys
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV
| | - Wen-Hong Li
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Roger H Unger
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX
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Damond N, Thorel F, Moyers JS, Charron MJ, Vuguin PM, Powers AC, Herrera PL. Blockade of glucagon signaling prevents or reverses diabetes onset only if residual β-cells persist. eLife 2016; 5. [PMID: 27092792 PMCID: PMC4871705 DOI: 10.7554/elife.13828] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/07/2016] [Indexed: 12/15/2022] Open
Abstract
Glucagon secretion dysregulation in diabetes fosters hyperglycemia. Recent studies report that mice lacking glucagon receptor (Gcgr-/-) do not develop diabetes following streptozotocin (STZ)-mediated ablation of insulin-producing β-cells. Here, we show that diabetes prevention in STZ-treated Gcgr-/- animals requires remnant insulin action originating from spared residual β-cells: these mice indeed became hyperglycemic after insulin receptor blockade. Accordingly, Gcgr-/- mice developed hyperglycemia after induction of a more complete, diphtheria toxin (DT)-induced β-cell loss, a situation of near-absolute insulin deficiency similar to type 1 diabetes. In addition, glucagon deficiency did not impair the natural capacity of α-cells to reprogram into insulin production after extreme β-cell loss. α-to-β-cell conversion was improved in Gcgr-/- mice as a consequence of α-cell hyperplasia. Collectively, these results indicate that glucagon antagonism could i) be a useful adjuvant therapy in diabetes only when residual insulin action persists, and ii) help devising future β-cell regeneration therapies relying upon α-cell reprogramming. DOI:http://dx.doi.org/10.7554/eLife.13828.001 After meals, digested food causes sugar to accumulate in the blood. This triggers the release of the hormone insulin from beta cells in the pancreas, which allows liver cells, muscle cells and fat cells to use and store the sugar for energy. Other cells in the pancreas, called alpha cells, release a hormone called glucagon that counteracts the effects of insulin by telling the liver to release sugar into the bloodstream. The balance between the activity of insulin and glucagon keeps blood sugar levels steady. Diabetes results from the body being unable to produce enough insulin or respond to the insulin that is produced, which results in sugar accumulating in the blood. Diabetes also increases the production of glucagon, which further increases blood sugar levels. Recently, some researchers have reported that mice that lack the receptor proteins through which glucagon works do not develop diabetes, even when they are treated with a drug called streptozotocin that wipes out most of their beta cells. This suggests that the high blood sugar levels seen in diabetes result from an excess of glucagon, and not a lack of insulin. Drugs that block the action of glucagon have been found to reduce the symptoms of mild diabetes in mice and are now being tested in humans. However, it is less clear whether this treatment has any benefits in animals with more severe diabetes. Streptozotocin destroys most of a mouse’s beta cells but a significant fraction of them persist, while a different system relying on diphtheria toxin destroys more than 99% of these cells. Damond et al. have now found that treating mice that lack glucagon receptors with diphtheria toxin causes the mice to develop severe diabetes. Mice that lacked glucagon receptors that had been treated with streptozotocin also developed diabetes after they had been treated with an insulin-blocking drug. Further experiments showed that blocking glucagon receptors in typical mice with diabetes reduces blood sugar, but only if there is some insulin left in their bodies. Damond et al. also found that the glucagon receptor-lacking mice have more alpha cells, which have the ability to convert into insulin-producing cells after the widespread destruction of beta cells. Together, the experiments suggest that blocking glucagon could be a useful treatment for diabetes, but only in individuals who still have some insulin-producing cells. Such treatment would help reduce the release of sugar from the liver and increase the production of insulin in converted alpha cells in the pancreas. Damond et al. are now investigating how alpha cells convert into beta cells, with the aim of learning how to make beta cells regenerate more efficiently. DOI:http://dx.doi.org/10.7554/eLife.13828.002
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Affiliation(s)
- Nicolas Damond
- Department of Genetic Medicine and Development of the Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva, University of Geneva, Geneva, Switzerland.,Centre facultaire du diabète, University of Geneva, Geneva, Switzerland
| | - Fabrizio Thorel
- Department of Genetic Medicine and Development of the Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva, University of Geneva, Geneva, Switzerland.,Centre facultaire du diabète, University of Geneva, Geneva, Switzerland
| | - Julie S Moyers
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, United States
| | - Maureen J Charron
- Departments of Biochemistry, Medicine, and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, United States
| | - Patricia M Vuguin
- Pediatric Endocrinology, Women's and Childrens Health, College of Physicians & Surgeons, Columbia University, New York, United States
| | - Alvin C Powers
- Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Department of Molecular Physiology, Vanderbilt University, Nashville, United States.,VA Tennessee Valley Healthcare System, Nashville, United States
| | - Pedro L Herrera
- Department of Genetic Medicine and Development of the Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva, University of Geneva, Geneva, Switzerland.,Centre facultaire du diabète, University of Geneva, Geneva, Switzerland
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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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Abstract
The alpha cells that co-occupy the islets in association with beta cells have been long recognized as the source of glucagon, a hyperglycemia-producing and diabetogenic hormone. Although the mechanisms that control the functions of alpha cells, glucagon secretion, and the role of glucagon in diabetes have remained somewhat enigmatic over the fifty years since their discovery, seminal findings during the past few years have moved alpha cells into the spotlight of scientific discovery. These findings obtained largely from studies in mice are: Alpha cells have the capacity to trans-differentiate into insulin-producing beta cells. Alpha cells contain a GLP-1 generating system that produces GLP-1 locally for paracrine actions within the islets that likely promotes beta cell growth and survival and maintains beta cell mass. Impairment of glucagon signaling both prevents the occurrence of diabetes in conditions of the near absence of insulin and expands alpha cell mass. Alpha cells appear to serve as helper cells or guardians of beta cells to ensure their health and well-being. Of potential relevance to the possibility of promoting the transformation of alpha to beta cells is the observation that impairment of glucagon signaling leads to a marked increase in alpha cell mass in the islets. Such alpha cell hyperplasia provides an increased supply of alpha cells for their transdifferentiation into new beta cells. In this review we discuss these recent discoveries from the perspective of their potential relevance to the treatment of diabetes.
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Affiliation(s)
- Violeta Stanojevic
- Laboratory of Molecular Endocrinology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Joel F Habener
- Laboratory of Molecular Endocrinology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
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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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38
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Basso AMM, Pelegrini PB, Mulinari F, Costa MC, Viana AB, Silva LP, Grossi-de-Sa MF. Recombinant glucagon: a differential biological activity. AMB Express 2015; 5:20. [PMID: 25852997 PMCID: PMC4385203 DOI: 10.1186/s13568-015-0099-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/22/2015] [Indexed: 11/13/2022] Open
Abstract
In Brazil, there is a growing demand for specialised pharmaceuticals, and the high cost of their importation results in increasing costs, reaching US$ 1.34 billion in 2012 and US$ 1.61 billion in 2013. Worldwide expenses related to drugs could reach US$ 1.3 trillion in 2018, especially due to new treatments for hepatitis C and cancer. Specialised or high-cost pharmaceutical drugs used for the treatment of viral hepatitis, multiple sclerosis, HIV and diabetes are distributed free of charge by the Brazilian government. The glucagon peptide was included in this group of high-cost biopharmaceuticals in 2008. Although its main application is the treatment of hypoglycaemia in diabetic patients, it can also be used with patients in an alcoholic coma, for those patients with biliary tract pain, and as a bronchodilator. Therefore, in order to reduce biopharmaceutical production costs, the Brazilian government passed laws focusing on the development and increase of a National Pharmaceutical Industrial Centre, including the demand for the national production of glucagon. For that reason and given the importance and high cost of recombinant glucagon, the purpose of this study was to develop methods to improve production, purification and performance of the biological activity of recombinant glucagon. Glucagon was recombined into a plasmid vector containing a Glutathione S-transferase tag, and the peptide was expressed in a heterologous Escherichia coli system. After purification procedures and molecular analyses, the biological activity of this recombinant glucagon was examined using in vivo assays and showed a highly significant (p < 0.00001) and prolonged effect on glucose levels when compared with the standard glucagon. The experimental procedure described here facilitates the high level production of recombinant glucagon with an extended biological activity.
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Affiliation(s)
- Angelina M M Basso
- />Department of Molecular Pathology, University of Brasilia, Brasilia, DF Brazil
- />Laboratory of Plant-Pest Interaction, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
| | - Patrícia B Pelegrini
- />Laboratory of Plant-Pest Interaction, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
| | - Fernanda Mulinari
- />Laboratory of Plant-Pest Interaction, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
- />Pioneer Union for Social Insertion – UPIS, Planaltina, DF Brazil
| | - Michelle C Costa
- />Laboratory of Plant-Pest Interaction, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
| | - Antonio B Viana
- />Laboratory of Plant-Pest Interaction, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
- />Catholic University of Brasilia, Brasilia, DF Brazil
| | - Luciano P Silva
- />Laboratory of Mass Spectrometry, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
| | - Maria Fatima Grossi-de-Sa
- />Laboratory of Plant-Pest Interaction, Embrapa – Genetic Resources and Biotechnology, Brasília, DF Brazil
- />Catholic University of Brasilia, Brasilia, DF Brazil
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The Constitutive Activation of Egr-1/C/EBPa Mediates the Development of Type 2 Diabetes Mellitus by Enhancing Hepatic Gluconeogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:513-23. [DOI: 10.1016/j.ajpath.2014.10.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 09/28/2014] [Accepted: 10/02/2014] [Indexed: 12/13/2022]
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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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Terry NA, Walp ER, Lee RA, Kaestner KH, May CL. Impaired enteroendocrine development in intestinal-specific Islet1 mouse mutants causes impaired glucose homeostasis. Am J Physiol Gastrointest Liver Physiol 2014; 307:G979-91. [PMID: 25214396 PMCID: PMC4233286 DOI: 10.1152/ajpgi.00390.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Enteroendocrine cells secrete over a dozen different hormones responsible for coordinating digestion, absorption, metabolism, and gut motility. Loss of enteroendocrine cells is a known cause of severe congenital diarrhea. Furthermore, enteroendocrine cells regulate glucose metabolism, with the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) playing critical roles in stimulating insulin release by pancreatic β-cells. Islet1 (Isl1) is a LIM-homeodomain transcription factor expressed specifically in an array of intestinal endocrine cells, including incretin-expressing cells. To examine the impact of intestinal Isl1 on glycemic control, we set out to explore the role of intestinal Isl1 in hormone cell specification and organismal physiology. Mice with intestinal epithelial-specific ablation of Isl1 were obtained by crossing Villin-Cre transgenic animals with mice harboring a Isl1(loxP) allele (Isl1(int) model). Gene ablation of Isl1 in the intestine results in loss of GLP-1, GIP, cholecystokinin (CCK), and somatostatin-expressing cells and an increase in 5-HT (serotonin)-producing cells, while the chromogranin A population was unchanged. This dramatic change in hormonal milieu results in animals with lipid malabsorption and females smaller than their littermate controls. Interestingly, when challenged with oral, not intraperitoneal glucose, the Isl-1 intestinal-deficient animals (Isl1(int)) display impaired glucose tolerance, indicating loss of the incretin effect. Thus the Isl1(int) model confirms that intestinal biology is essential for organism physiology in glycemic control and susceptibility to diabetes.
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Affiliation(s)
- Natalie A. Terry
- 1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; ,2Division of Gastroenterology and Nutrition, Department of Pediatrics, Philadelphia, Pennsylvania; ,3Department of Pathology and Laboratory Medicine, Philadelphia, Pennsylvania; and
| | - Erik R. Walp
- 1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; ,3Department of Pathology and Laboratory Medicine, Philadelphia, Pennsylvania; and
| | - Randall A. Lee
- 1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; ,2Division of Gastroenterology and Nutrition, Department of Pediatrics, Philadelphia, Pennsylvania;
| | - Klaus H. Kaestner
- 4Perelman School of Medicine at the University of Pennsylvania, Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, Philadelphia, Pennsylvania
| | - Catherine Lee May
- 1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; ,2Division of Gastroenterology and Nutrition, Department of Pediatrics, Philadelphia, Pennsylvania; ,3Department of Pathology and Laboratory Medicine, Philadelphia, Pennsylvania; and
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42
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Ahrén B, Gautier JF, Berria R, Stager W, Aronson R, Bailey CJ. Pronounced reduction of postprandial glucagon by lixisenatide: a meta-analysis of randomized clinical trials. Diabetes Obes Metab 2014; 16:861-8. [PMID: 24641271 DOI: 10.1111/dom.12290] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 12/19/2013] [Accepted: 03/11/2014] [Indexed: 01/03/2023]
Abstract
AIM Glucagon-like peptide-1 (GLP-1) receptor agonists improve islet function and delay gastric emptying in patients with type 2 diabetes mellitus (T2DM). This meta-analysis aimed to investigate the effects of the once-daily prandial GLP-1 receptor agonist lixisenatide on postprandial plasma glucose (PPG), glucagon and insulin levels. METHODS Six randomized, placebo-controlled studies of lixisenatide 20 µg once daily were included in this analysis: lixisenatide as monotherapy (GetGoal-Mono), as add-on to oral antidiabetic drugs (OADs; GetGoal-M, GetGoal-S) or in combination with basal insulin (GetGoal-L, GetGoal-Duo-1 and GetGoal-L-Asia). Change in 2-h PPG and glucose excursion were evaluated across six studies. Change in 2-h glucagon and postprandial insulin were evaluated across two studies. A meta-analysis was performed on least square (LS) mean estimates obtained from analysis of covariance (ANCOVA)-based linear regression. RESULTS Lixisenatide significantly reduced 2-h PPG from baseline (LS mean difference vs. placebo: -4.9 mmol/l, p < 0.001) and glucose excursion (LS mean difference vs. placebo: -4.5 mmol/l, p < 0.001). As measured in two studies, lixisenatide also reduced postprandial glucagon (LS mean difference vs. placebo: -19.0 ng/l, p < 0.001) and insulin (LS mean difference vs. placebo: -64.8 pmol/l, p < 0.001). There was a stronger correlation between 2-h postprandial glucagon and 2-h PPG with lixisenatide than with placebo. CONCLUSIONS Lixisenatide significantly reduced 2-h PPG and glucose excursion together with a marked reduction in postprandial glucagon and insulin; thus, lixisenatide appears to have biological effects on blood glucose that are independent of increased insulin secretion. These effects may be, in part, attributed to reduced glucagon secretion.
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Affiliation(s)
- B Ahrén
- Department of Clinical Sciences, Lund University, Lund, Sweden
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43
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Johswich A, Longuet C, Pawling J, Abdel Rahman A, Ryczko M, Drucker DJ, Dennis JW. N-glycan remodeling on glucagon receptor is an effector of nutrient sensing by the hexosamine biosynthesis pathway. J Biol Chem 2014; 289:15927-41. [PMID: 24742675 DOI: 10.1074/jbc.m114.563734] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Glucose homeostasis in mammals is dependent on the opposing actions of insulin and glucagon. The Golgi N-acetylglucosaminyltransferases encoded by Mgat1, Mgat2, Mgat4a/b/c, and Mgat5 modify the N-glycans on receptors and solute transporter, possibly adapting activities in response to the metabolic environment. Herein we report that Mgat5(-/-) mice display diminished glycemic response to exogenous glucagon, together with increased insulin sensitivity. Glucagon receptor signaling and gluconeogenesis in Mgat5(-/-) cultured hepatocytes was impaired. In HEK293 cells, signaling by ectopically expressed glucagon receptor was increased by Mgat5 expression and GlcNAc supplementation to UDP-GlcNAc, the donor substrate shared by Mgat branching enzymes. The mobility of glucagon receptor in primary hepatocytes was reduced by galectin-9 binding, and the strength of the interaction was dependent on Mgat5 and UDP-GlcNAc levels. Finally, oral GlcNAc supplementation rescued the glucagon response in Mgat5(-/-) hepatocytes and mice, as well as glycolytic metabolites and UDP-GlcNAc levels in liver. Our results reveal that the hexosamine biosynthesis pathway and GlcNAc salvage contribute to glucose homeostasis through N-glycan branching on glucagon receptor.
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Affiliation(s)
- Anita Johswich
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and
| | - Christine Longuet
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and
| | - Judy Pawling
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and
| | - Anas Abdel Rahman
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and
| | - Michael Ryczko
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and the Departments of Molecular Genetics
| | - Daniel J Drucker
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and Medicine, University of Toronto, Toronto, Ontario M5R 0A3, Canada
| | - James W Dennis
- From the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada and the Departments of Molecular Genetics, Laboratory Medicine and Pathology, and Medicine, University of Toronto, Toronto, Ontario M5R 0A3, Canada
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44
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Abstract
Glucose homeostasis is precisely regulated by glucagon and insulin, which are released by pancreatic α- and β-cells, respectively. While β-cells have been the focus of intense research, less is known about α-cell function and the actions of glucagon. In recent years, the study of this endocrine cell type has experienced a renewed drive. The present review contains a summary of established concepts as well as new information about the regulation of α-cells by glucose, amino acids, fatty acids and other nutrients, focusing especially on glucagon release, glucagon synthesis and α-cell survival. We have also discussed the role of glucagon in glucose homeostasis and in energy and lipid metabolism as well as its potential as a modulator of food intake and body weight. In addition to the well-established action on the liver, we discuss the effects of glucagon in other organs, where the glucagon receptor is expressed. These tissues include the heart, kidneys, adipose tissue, brain, small intestine and the gustatory epithelium. Alterations in α-cell function and abnormal glucagon concentrations are present in diabetes and are thought to aggravate the hyperglycaemic state of diabetic patients. In this respect, several experimental approaches in diabetic models have shown important beneficial results in improving hyperglycaemia after the modulation of glucagon secretion or action. Moreover, glucagon receptor agonism has also been used as a therapeutic strategy to treat obesity.
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45
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Zhang L, Jia X, Dong J, Chen D, Liu J, Zhang L, Wen X. Synthesis and evaluation of novel oleanolic acid derivatives as potential antidiabetic agents. Chem Biol Drug Des 2014; 83:297-305. [PMID: 24119242 DOI: 10.1111/cbdd.12241] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/28/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
Abstract
Antidiabetic agents simultaneously inhibiting hepatic glucose production and stimulating hepatic glucose consumption could apply a better control over hyperglycemia. A series of oleanolic acid derivatives with bulky substituents at C-3 position were designed and synthesized in order to search for this kind of agents. All of the compounds were evaluated biologically in vitro using glycogen phosphorylase and HepG2 cells. The results indicated that several derivatives exhibited moderate-to-good inhibitory activities against glycogen phosphorylase. Compound 8g showed the best inhibition with an IC50 value of 5.4 μm. Moreover, most of the derivatives were found to increase the glucose consumption in HepG2 cells in a dose-dependent manner. The possible binding mode of compound 8g with glycogen phosphorylase was also explored by docking study. 8g was found to have hydrogen bonding interactions with Arg193, Arg310, and Arg60 of the allosteric site.
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Affiliation(s)
- Liying Zhang
- Key Laboratory of Traditional Chinese Medicine Research and Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde, 067000, China
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46
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Wilcox CL, Terry NA, May CL. Arx polyalanine expansion in mice leads to reduced pancreatic α-cell specification and increased α-cell death. PLoS One 2013; 8:e78741. [PMID: 24236044 PMCID: PMC3827280 DOI: 10.1371/journal.pone.0078741] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 09/23/2013] [Indexed: 11/18/2022] Open
Abstract
ARX/Arx is a homeodomain-containing transcription factor necessary for the specification and early maintenance of pancreatic endocrine α-cells. Many transcription factors important to pancreas development, including ARX/Arx, are also crucial for proper brain development. Although null mutations of ARX in human patients result in the severe neurologic syndrome XLAG (X-linked lissencephaly associated with abnormal genitalia), the most common mutation is the expansion of the first polyalanine tract of ARX, which results primarily in the clinical syndrome ISSX (infantile spasms). Mouse models of XLAG, ISSX and other human ARX mutations demonstrate a direct genotype-phenotype correlation in ARX-related neurologic disorders. Furthermore, mouse models utilizing a polyalanine tract expansion mutation have illustrated critical developmental differences between null mutations and expansion mutations in the brain, revealing context-specific defects. Although Arx is known to be required for the specification and early maintenance of pancreatic glucagon-producing α-cells, the consequences of the Arx polyalanine expansion on pancreas development remain unknown. Here we report that mice with an expansion mutation in the first polyalanine tract of Arx exhibit impaired α-cell specification and maintenance, with gradual α-cell loss due to apoptosis. This is in contrast to the re-specification of α-cells into β- and δ-cells that occurs in mice null for Arx. Overall, our analysis of an Arx polyalanine expansion mutation on pancreatic development suggests that impaired α-cell function might also occur in ISSX patients.
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Affiliation(s)
- Crystal L. Wilcox
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Natalie A. Terry
- Department of Pediatrics, Division of Gastroenterology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Catherine Lee May
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Shiota C, Prasadan K, Guo P, El-Gohary Y, Wiersch J, Xiao X, Esni F, Gittes GK. α-Cells are dispensable in postnatal morphogenesis and maturation of mouse pancreatic islets. Am J Physiol Endocrinol Metab 2013; 305:E1030-40. [PMID: 23982158 DOI: 10.1152/ajpendo.00022.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-producing α-cells are the second-most abundant cell type in the islet. Whereas α-cells make up less than 20% of the cells in a mature mouse islet, they occupy a much larger proportion of the pancreatic endocrine cell population during the early postnatal period, the time when morphological and functional maturation occurs to form adult islets. To determine whether α-cells have a role in postnatal islet development, a diphtheria toxin-mediated α-cell ablation mouse model was established. Rapid and persistent depletion of α-cells was achieved by daily injection of the toxin for 2 wk starting at postnatal day 1 (P1). Total pancreatic glucagon content in the α-cell-ablated mice was undetectable at P14 and still less than 0.3% of that of the control mice at 4 mo of age. Histological analyses revealed that formation of spherical islets occurred normally, and the islet size distribution was not changed despite the near-total lack of α-cells. Furthermore, there were no differences in expression of β-cell maturation marker proteins, including urocortin 3 and glucose transporter 2, in the α-cell-ablated islets at P14. Mice lacking α-cells grew normally and appeared healthy. Both glucose and insulin tolerance tests demonstrated that the α-cell-ablated mice had normal glucose homeostasis. These results indicate that α-cells do not play a critical role in postnatal islet morphogenesis or functional maturation of β-cells.
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Affiliation(s)
- Chiyo Shiota
- Division of Pediatric General and Thoracic Surgery, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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48
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Elimination of von Hippel-Lindau function perturbs pancreas endocrine homeostasis in mice. PLoS One 2013; 8:e72213. [PMID: 23977255 PMCID: PMC3748057 DOI: 10.1371/journal.pone.0072213] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 07/08/2013] [Indexed: 12/23/2022] Open
Abstract
Mutations in the human homolog of the Vhlh gene [encoding the von-Hippel Lindau (VHL) protein] lead to tumor development. In mice, depletion of Vhlh in pancreatic ß-cells causes perturbed glucose homeostasis, but the role of this gene in other pancreatic cells is poorly understood. To investigate the function of VHL/HIF pathway in pancreatic cells, we inactivated Vhlh in the pancreatic epithelium as well as in the endocrine and exocrine lineages. Our results show that embryonic depletion of Vhlh within the pancreatic epithelium causes postnatal lethality due to severe hypoglycemia. The hypoglycemia is recapitulated in mice with endocrine-specific removal of Vhlh, while animals with loss of Vhlh predominantly in the exocrine compartment survive to adulthood with no overt defects in glucose metabolism. Mice with hypoglycemia display diminished insulin release in response to elevated glucose. Significantly, the glucagon response is impaired both in vivo (circulating glucagon levels) as well as in an in vitro secretion assay in isolated islets. Hypoxia also impairs glucagon secretion in a glucagon-expressing cell line in culture. Our results reveal a novel role for the hypoxia/HIF pathway in islet hormone secretion and maintenance of the fine balance that allows for the establishment of normoglycemia.
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Wilcox CL, Terry NA, Walp ER, Lee RA, May CL. Pancreatic α-cell specific deletion of mouse Arx leads to α-cell identity loss. PLoS One 2013; 8:e66214. [PMID: 23785486 PMCID: PMC3681972 DOI: 10.1371/journal.pone.0066214] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Accepted: 05/06/2013] [Indexed: 02/06/2023] Open
Abstract
The specification and differentiation of pancreatic endocrine cell populations (α-, β-, δ, PP- and ε-cells) is orchestrated by a combination of transcriptional regulators. In the pancreas, Aristaless-related homeobox gene (Arx) is expressed first in the endocrine progenitors and then restricted to glucagon-producing α-cells. While the functional requirement of Arx in early α-cell specification has been investigated, its role in maintaining α-cell identity has yet to be explored. To study this later role of Arx, we have generated mice in which the Arx gene has been ablated specifically in glucagon-producing α-cells. Lineage-tracing studies and immunostaining analysis for endocrine hormones demonstrate that ablation of Arx in neonatal α-cells results in an α-to-β-like conversion through an intermediate bihormonal state. Furthermore, these Arx-deficient converted cells express β-cell markers including Pdx1, MafA, and Glut2. Surprisingly, short-term ablation of Arx in adult mice does not result in a similar α-to-β-like conversion. Taken together, these findings reveal a potential temporal requirement for Arx in maintaining α-cell identity.
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Affiliation(s)
- Crystal L. Wilcox
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Natalie A. Terry
- Department of Pediatrics, Division of Gastroenterology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Erik R. Walp
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Randall A. Lee
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Catherine Lee May
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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50
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Xu S, Hayashi Y, Takagishi Y, Itoh M, Murata Y. Aristaless-related homeobox plays a key role in hyperplasia of the pancreas islet α-like cells in mice deficient in proglucagon-derived peptides. PLoS One 2013; 8:e64415. [PMID: 23671715 PMCID: PMC3650067 DOI: 10.1371/journal.pone.0064415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/14/2013] [Indexed: 12/12/2022] Open
Abstract
Defects in glucagon action can cause hyperplasia of islet α-cells, however, the underlying mechanisms remain largely to be elucidated. Mice homozygous for a glucagon-GFP knock-in allele (Gcggfp/gfp) completely lack proglucagon-derived peptides and exhibit hyperplasia of GFP-positive α-like cells. Expression of the transcription factor, aristaless-related homeobox (ARX), is also increased in the Gcggfp/gfp pancreas. Here, we sought to elucidate the role of ARX in the hyperplasia of α-like cells through analyses of two Arx mutant alleles (ArxP355L/Y and Arx [330insGCG]7/Y) that have different levels of impairment of their function. Expression of Gfp and Arx genes was higher and the size and number of islets increased in the Gcggfp/gfp pancreas compared to and Gcggfp/+ pancreas at 2 weeks of age. In male Gcggfp/gfp mice that are hemizygous for the ArxP355L/Y mutation that results in a protein with a P355L amino acid substitution, expression of Gfp mRNA in the pancreas was comparable to that in control Gcggfp/+Arx+/Y mice. The increases in islet size and number were also reduced in these mice. Immunohistochemical analysis showed that the number of GFP-positive cells was comparable in Gcggfp/gfp ArxP355L/Y and Gcggfp/+Arx+/Y mice. These results indicate that the hyperplasia is reduced by introduction of an Arx mutation. ArxP355L/Y mice appeared to be phenotypically normal; however, Arx [330insGCG]7/Y mice that have a mutant ARX protein with expansion of the polyalanine tract had a reduced body size and shortened life span. The number of GFP positive cells was further reduced in the Gcggfp/gfp Arx [330insGCG]7/Y mice. Taken together, our findings show that the function of ARX is one of the key modifiers for hyperplasia of islet α-like cells in the absence of proglucagon-derived peptides.
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Affiliation(s)
- Sai Xu
- Department of Genetics, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Yoshitaka Hayashi
- Department of Genetics, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
- * E-mail:
| | - Yoshiko Takagishi
- Department of Genetics, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Mariko Itoh
- Technical Department, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Yoshiharu Murata
- Department of Genetics, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
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