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Yan B, Li X, Peng M, Zuo Y, Wang Y, Liu P, Ren W, Jin X. The YTHDC1/GLUT3/RNF183 axis forms a positive feedback loop that modulates glucose metabolism and bladder cancer progression. Exp Mol Med 2023; 55:1145-1158. [PMID: 37258572 PMCID: PMC10318083 DOI: 10.1038/s12276-023-00997-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 02/09/2023] [Accepted: 02/24/2023] [Indexed: 06/02/2023] Open
Abstract
Aberrant glucose metabolism is a characteristic of bladder cancer. Hyperglycemia contributes to the development and progression of bladder cancer. However, the underlying mechanism by which hyperglycemia promotes the aggressiveness of cancers, especially bladder cancer, is still incompletely understood. N6-methyladenosine (m6A) modification is a kind of methylation modification occurring at the N6 position of adenosine that is important for the pathogenesis of urological tumors. Recently, it was found that the m6A reader YTHDC1 is regulated by high-glucose conditions. In our study, we revealed that YTHDC1 is not only regulated by high-glucose conditions but is also downregulated in bladder cancer tissue and associated with the prognosis of cancer. We also showed that YTHDC1 suppresses the malignant progression of and the glycolytic process in bladder cancer cells in an m6A-dependent manner and determined that this effect is partially mediated by GLUT3. Moreover, GLUT3 was found to destabilize YTHDC1 by upregulating RNF183 expression. In summary, we identified a novel YTHDC1/GLUT3/RNF183 feedback loop that regulates disease progression and glucose metabolism in bladder cancer. Collectively, this study provides new insight regarding the pathogenesis of bladder cancer under hyperglycemic conditions and might reveal ideal candidates for the development of drugs for bladder cancer.
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Affiliation(s)
- Bin Yan
- Department of Urology, The Second Xiangya Hospital, Central South University, 410011, Changsha, Hunan, China
- Uro-Oncology Institute of Central South University, 410011, Changsha, Hunan, China
| | - Xurui Li
- Department of Urology, The Second Xiangya Hospital, Central South University, 410011, Changsha, Hunan, China
- Uro-Oncology Institute of Central South University, 410011, Changsha, Hunan, China
| | - Mou Peng
- Department of Urology, The Second Xiangya Hospital, Central South University, 410011, Changsha, Hunan, China
- Uro-Oncology Institute of Central South University, 410011, Changsha, Hunan, China
| | - Yali Zuo
- Department of Urology, The Second Xiangya Hospital, Central South University, 410011, Changsha, Hunan, China
| | - Yinhuai Wang
- Department of Urology, The Second Xiangya Hospital, Central South University, 410011, Changsha, Hunan, China
| | - Pian Liu
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022, Wuhan, China.
| | - Weigang Ren
- Department of Urology, Hunan Provincial People's Hospital, The First Affiliated Hospital of Hunan Normal University, 410005, Changsha, Hunan, China.
| | - Xin Jin
- Department of Urology, The Second Xiangya Hospital, Central South University, 410011, Changsha, Hunan, China.
- Uro-Oncology Institute of Central South University, 410011, Changsha, Hunan, China.
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Garg R, Katekar R, Parwez S, Agarwal A, Sahu S, Dadge S, Verma S, Goand UK, Siddiqi MI, Gayen JR. Pancreastatin inhibitor PSTi8 ameliorates streptozotocin-induced diabetes by suppressing hepatic glucose production. Eur J Pharmacol 2023; 944:175559. [PMID: 36764353 DOI: 10.1016/j.ejphar.2023.175559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 01/27/2023] [Accepted: 01/30/2023] [Indexed: 02/11/2023]
Abstract
Elevated plasma glucose concentration, as a consequence of excessive hepatic glucose production, plays a pivotal role in the development of diabetes. A chromogranin A-derived diabetogenic peptide Pancreastatin (PST) enhances hepatic glucose output leading to diabetes. Therefore, here we probed the role of PSTi8, a PST inhibitor in ameliorating diabetes by investigating the effect of high glucose (HG) or PST on glucose metabolism. Further, we also explored the action mechanism of the underlying anti-hyperglycemic effect of PSTi8. PSTi8 treatment rescue cultured L6 and HepG2 cells from HG and PST-induced insulin resistance, respectively. It also enhances insulin receptor kinase activity by interacting with the insulin receptor and enhancing GLUT4 translocation and glucose uptake. Thus, our in-silico and in-vitro data support the PST-dependent and independent activity of PSTi8. Additionally, PSTi8 treatment in streptozotocin-induced diabetic rats improved glucose tolerance by lowering blood glucose and plasma PST levels. Concomitantly, the treated animals exhibited reduced hepatic glucose production accompanied by downregulation of hepatic gluconeogenic genes PEPCK and G6Pase. PSTi8-treated rats also exhibited enhanced hepatic glycogen in line with reduced plasma glucagon concentrations. Consistently, improved plasma insulin levels in PSTi8-treated rats enhanced skeletal muscle glucose disposal via enhanced P-Akt expression. In summary, these findings suggest PSTi8 has anti-hyperglycemic properties with enhanced skeletal muscle glucose disposal and reduced hepatic gluconeogenesis both PST dependent as well as independent.
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Affiliation(s)
- Richa Garg
- Pharmaceutics & Pharmacokinetics, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Roshan Katekar
- Pharmaceutics & Pharmacokinetics, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Shahid Parwez
- Biochemistry and Structural Biology, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Arun Agarwal
- Pharmaceutics & Pharmacokinetics, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | | | | | - Saurabh Verma
- Pharmaceutics & Pharmacokinetics, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Umesh K Goand
- Pharmaceutics & Pharmacokinetics, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Mohammad Imran Siddiqi
- Biochemistry and Structural Biology, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Jiaur R Gayen
- Pharmaceutics & Pharmacokinetics, India; Pharmacology Division, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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Kobayashi M, Maruyama N, Yamamoto Y, Togawa T, Ida T, Yoshida M, Miyazato M, Kitada M, Hayashi Y, Kashiwagi A, Kitamura T. A newly developed glucagon sandwich ELISA is useful for more accurate glucagon evaluation than the currently used sandwich ELISA in subjects with elevated plasma proglucagon-derived peptide levels. J Diabetes Investig 2023; 14:648-658. [PMID: 36729958 PMCID: PMC10119918 DOI: 10.1111/jdi.13986] [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: 09/21/2022] [Revised: 01/12/2023] [Accepted: 01/18/2023] [Indexed: 02/03/2023] Open
Abstract
AIMS/INTRODUCTION Glucagon, a peptide hormone produced from proglucagon, is involved in the pathophysiology of diabetes. Plasma glucagon levels are currently measured by sandwich enzyme-linked immunosorbent assay (ELISA), but the currently used sandwich ELISA cross-reacts with proglucagon-derived peptides, thereby providing incorrect results in subjects with elevated plasma proglucagon-derived peptide levels. We aimed to develop a more broadly reliable ELISA for measuring plasma glucagon levels. MATERIALS AND METHODS A new sandwich ELISA was developed using newly generated monoclonal antibodies against glucagon. After its validation, plasma glucagon levels were measured with the new ELISA and the currently used ELISA in subjects who underwent laparoscopic sleeve gastrectomy (LSG) and in outpatients with suspected glucose intolerance. The ELISA results were compared with those from liquid chromatography-high resolution mass (LC-HRMS) analysis, which we previously established as the most accurate measuring system. RESULTS The new ELISA has high specificity (<1% cross-reactivities) and high sensitivity (a lower range of 0.31 pmol/L). Plasma glucagon values in the subjects who underwent laparoscopic sleeve gastrectomy and some outpatients with suspected glucose intolerance differed between the new ELISA and the currently used ELISA. These subjects also showed markedly high plasma glicentin levels. Despite the elevated plasma glicentin levels, the new ELISA showed better positive correlation with LC-HRMS than did the currently used ELISA. CONCLUSIONS The new ELISA enables more accurate measurement of plasma glucagon than the currently used ELISA, even in subjects with elevated proglucagon-derived peptide levels. It should be clinically useful in elucidating the pathophysiology of individual diabetic patients.
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Affiliation(s)
- Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | | | - Yukako Yamamoto
- Department of Diabetes and Endocrinology, Omi Medical Center, Shiga, Japan
| | - Takeshi Togawa
- Department of Bariatric and Metabolic Surgery, Omi Medical Center, Shiga, Japan
| | - Takanori Ida
- Division for Identification and Analysis of Bioactive Peptides, Department of Bioactive Peptides, Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Morikatsu Yoshida
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Mikiya Miyazato
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | | | - Yoshitaka Hayashi
- Division of Stress Adaptation and Protection, Department of Endocrinology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Atsunori Kashiwagi
- Department of Diabetes and Endocrinology, Omi Medical Center, Shiga, Japan
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
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Kim YK, Munir KM, Davis SN. Type 1 diabetes: key drug targets and how they could influence future therapeutics. Expert Opin Ther Targets 2023; 27:31-40. [PMID: 36744390 DOI: 10.1080/14728222.2023.2177150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Despite significant strides made in the management of T1DM, standard management is still insulin analog therapy. Some non-insulin therapies traditionally reserved for the treatment of T2DM have been explored in caring for patients with T1DM, and pancreas transplant is an option for few. However, T1DM remains a challenging disease to manage, encouraging development of novel pharmacologic agents. AREAS COVERED We retrieved PubMed, Cochrane Library, Scopus, Google Scholar, and ClinicalTrials.gov records to identify studies and articles focused on new pharmacologic advances to treat T1DM. EXPERT OPINION Recent research has focused on new targets of pharmacologic treatment of T1DM. Beta-cell preservation through immunomodulation or inhibiting inflammation hopes to delay or halt the progression of the disease. Beta cell regeneration through islet cell transplant or modification in transcription pathways aim to reverse the disease effects. Multiple other new targets such as glucagon antagonism and glucokinase activation are also in development as a potential adjunctive therapy. These new therapeutic targets offer the hope of reducing the daily burden of diabetes management with eventual insulin discontinuation for many individuals with T1DM.
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Affiliation(s)
- Yoon Kook Kim
- Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Center for Diabetes and Endocrinology, 800 Linden Ave, 8th Floor, 21201, Baltimore, MD, USA
| | - Kashif M Munir
- Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Center for Diabetes and Endocrinology, 800 Linden Ave, 8th Floor, 21201, Baltimore, MD, USA
| | - Stephen N Davis
- Department of Medicine, University of Maryland School of Medicine, 22 South Greene Street, 21201, Baltimore, MD, USA
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Abstract
Post-surgical adhesions are a major complication leading to organ dysfunctions, pain, intestinal obstruction, and infertility. The incidence of post-surgical adhesion is really high. The factors involved in the pathogenesis of post-surgical fibrosis, are largely unknown, for example why two patients with similar abdominal operation have a different risks of adhesion severity? High secretion of pro-inflammatory cytokines and growth factors, includes tumour necrosis factor α (TNF-α), interleukin 6 (IL6), and transforming growth factor β (TGF-β) by persistent recruitment of immune cells and the inappropriate proliferated fibroblast/mesothelial cells can stimulate signalling pathways particularly TGF-β leads to the up-regulation of some pro-fibrotic genes that impair fibrinolytic activity and promote extracellular matrix (ECM) accumulation. In this review, we focus on the role of diabetes and hyperglycaemia on post-surgical fibrosis, including the molecular mechanisms affected by hyperglycaemia that cause inflammation, oxidative stress, and increase the expression of pro-fibrotic molecules.
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Affiliation(s)
- Gordon A Ferns
- Division of Medical Education, Brighton & Sussex Medical School, Brighton, UK
| | - Seyed Mahdi Hassanian
- Department of Clinical Biochemistry, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad-Hassan Arjmand
- Medical Plants Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
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6
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Knerr PJ, Mowery SA, Douros JD, Premdjee B, Hjøllund KR, He Y, Kruse Hansen AM, Olsen AK, Perez-Tilve D, DiMarchi RD, Finan B. Next generation GLP-1/GIP/glucagon triple agonists normalize body weight in obese mice. Mol Metab 2022; 63:101533. [PMID: 35809773 PMCID: PMC9305623 DOI: 10.1016/j.molmet.2022.101533] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/18/2022] [Accepted: 06/18/2022] [Indexed: 12/19/2022] Open
Abstract
Objective Pharmacological strategies that engage multiple mechanisms-of-action have demonstrated synergistic benefits for metabolic disease in preclinical models. One approach, concurrent activation of the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon (Gcg) receptors (i.e. triagonism), combines the anorectic and insulinotropic activities of GLP-1 and GIP with the energy expenditure effect of glucagon. While the efficacy of triagonism in preclinical models is known, the relative contribution of GcgR activation remains unassessed. This work aims to addresses that central question. Methods Herein, we detail the design of unimolecular peptide triagonists with an empirically optimized receptor potency ratio. These optimized peptide triagonists employ a protraction strategy permitting once-weekly human dosing. Additionally, we assess the effects of these peptides on weight-reduction, food intake, glucose control, and energy expenditure in an established DIO mouse model compared to clinically relevant GLP-1R agonists (e.g. semaglutide) and dual GLP-1R/GIPR agonists (e.g. tirzepatide). Results Optimized triagonists normalize body weight in DIO mice and enhance energy expenditure in a manner superior to that of GLP-1R mono-agonists and GLP-1R/GIPR co-agonists. Conclusions These pre-clinical data suggest unimolecular poly-pharmacology as an effective means to target multiple mechanisms contributing to obesity and further implicate GcgR activation as the differentiating factor between incretin receptor mono- or dual-agonists and triagonists. Details the design of unimolecular peptide triagonists for GLP-1R/GIPR/GCGR. Optimal weight-loss is achieved when receptor potency ratio is weighted toward GCGR vs GLP-1R or GIPR. These agonists are protracted for once-weekly human dosing. Optimized triagonists normalizes body weight & enhance energy expenditure in mice. Efficacy of optimized triagonists is superior to GLP-1R & GLP-1R/GIPR agonists.
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Affiliation(s)
- Patrick J Knerr
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | | | | | | | | | - Yantao He
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | | | | | - Diego Perez-Tilve
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | | | - Brian Finan
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA.
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7
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Wang X, Li J, Zhang W, Li P, Zhang W, Wang H, Tang B. Evaluating diabetic ketoacidosis via a MOF sensor for fluorescence imaging of phosphate and pH. Chem Commun (Camb) 2022; 58:3023-3026. [PMID: 35156674 DOI: 10.1039/d1cc06876h] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Herein, a new type of composite metal-organic framework sensor for evaluating diabetic ketoacidosis was designed and prepared using in situ fluorescence imaging of phosphate and pH, which provides a new way to effectively evaluate the diabetic complication-ketoacidosis in the early clinical stage.
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Affiliation(s)
- Xue Wang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
| | - Jin Li
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
| | - Wei Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
| | - Ping Li
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
| | - Wen Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
| | - Hui Wang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
| | - Bo Tang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Biomedical Sciences, Shandong Normal University, Jinan 250014, P. R. China.
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8
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Jia Y, Liu Y, Feng L, Sun S, Sun G. Role of Glucagon and Its Receptor in the Pathogenesis of Diabetes. Front Endocrinol (Lausanne) 2022; 13:928016. [PMID: 35784565 PMCID: PMC9243425 DOI: 10.3389/fendo.2022.928016] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/13/2022] [Indexed: 11/24/2022] Open
Abstract
Various theories for the hormonal basis of diabetes have been proposed and debated over the past few decades. Insulin insufficiency was previously regarded as the only hormone deficiency directly leading to metabolic disorders associated with diabetes. Although glucagon and its receptor are ignored in this framework, an increasing number of studies have shown that they play essential roles in the development and progression of diabetes. However, the molecular mechanisms underlying the effects of glucagon are still not clear. In this review, recent research on the mechanisms by which glucagon and its receptor contribute to the pathogenesis of diabetes as well as correlations between GCGR mutation rates in populations and the occurrence of diabetes are summarized. Furthermore, we summarize how recent research clearly establishes glucagon as a potential therapeutic target for diabetes.
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Affiliation(s)
- Yunbo Jia
- Innovative Engineering Technology Research Center for Cell Therapy, Shengjing Hospital of China Medical University, Shenyang, China
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yang Liu
- Innovative Engineering Technology Research Center for Cell Therapy, Shengjing Hospital of China Medical University, Shenyang, China
| | - Linlin Feng
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Siyu Sun
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
- *Correspondence: Siyu Sun, ; Guangwei Sun,
| | - Guangwei Sun
- Innovative Engineering Technology Research Center for Cell Therapy, Shengjing Hospital of China Medical University, Shenyang, China
- Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang, China
- *Correspondence: Siyu Sun, ; Guangwei Sun,
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9
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Wu B, Ye Y, Xie S, Li Y, Sun X, Lv M, Yang L, Cui N, Chen Q, Jensen LD, Cui D, Huang G, Zuo J, Zhang S, Liu W, Yang Y. Megakaryocytes Mediate Hyperglycemia-Induced Tumor Metastasis. Cancer Res 2021; 81:5506-5522. [PMID: 34535458 DOI: 10.1158/0008-5472.can-21-1180] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/19/2021] [Accepted: 09/15/2021] [Indexed: 11/16/2022]
Abstract
High blood glucose has long been established as a risk factor for tumor metastasis, yet the molecular mechanisms underlying this association have not been elucidated. Here we describe that hyperglycemia promotes tumor metastasis via increased platelet activity. Administration of glucose, but not fructose, reprogrammed the metabolism of megakaryocytes to indirectly prime platelets into a prometastatic phenotype with increased adherence to tumor cells. In megakaryocytes, a glucose metabolism-related gene array identified the mitochondrial molecular chaperone glucose-regulated protein 75 (GRP75) as a trigger for platelet activation and aggregation by stimulating the Ca2+-PKCα pathway. Genetic depletion of Glut1 in megakaryocytes blocked MYC-induced GRP75 expression. Pharmacologic blockade of platelet GRP75 compromised tumor-induced platelet activation and reduced metastasis. Moreover, in a pilot clinical study, drinking a 5% glucose solution elevated platelet GRP75 expression and activated platelets in healthy volunteers. Platelets from these volunteers promoted tumor metastasis in a platelet-adoptive transfer mouse model. Together, under hyperglycemic conditions, MYC-induced upregulation of GRP75 in megakaryocytes increases platelet activation via the Ca2+-PKCα pathway to promote cancer metastasis, providing a potential new therapeutic target for preventing metastasis. SIGNIFICANCE: This study provides mechanistic insights into a glucose-megakaryocyte-platelet axis that promotes metastasis and proposes an antimetastatic therapeutic approach by targeting the mitochondrial protein GRP75.
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Affiliation(s)
- Biying Wu
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ying Ye
- Department of Oral Implantology, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China
| | - Sisi Xie
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yintao Li
- Phase I Clinical Center, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Science, Jinan, China
| | - Xiaoting Sun
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Mengyuan Lv
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ling Yang
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Nan Cui
- Department of Reproductive Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Qiying Chen
- Department of Cardiology, Huashan Hospital Affiliated to Fudan University, Shanghai 200040, China
| | - Lasse D Jensen
- Department of Medicine, Health and Caring Science, Division of Diagnostics and Specialist Medicine, Unit of Cardiovascular Medicine, Linköping University, Linköping, Sweden
| | - Dongmei Cui
- Shenzhen Eye Hospital, Shenzhen Key Laboratory of Ophthalmology, Affiliated Shenzhen Eye Hospital of Jinan University, Shenzhen, China
| | - Guichun Huang
- Medical Oncology Department of Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Ji Zuo
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Shaochong Zhang
- Shenzhen Eye Hospital, Shenzhen Key Laboratory of Ophthalmology, Affiliated Shenzhen Eye Hospital of Jinan University, Shenzhen, China
| | - Wen Liu
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Yunlong Yang
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai, China.
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10
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Turbinafuranone A–C, new 2-furanone analogues from marine macroalga Turbinaria ornata as prospective anti-hyperglycemic agents attenuate tyrosine phosphatase-1B. Med Chem Res 2021. [DOI: 10.1007/s00044-021-02762-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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11
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Chen S, Sbuh N, Veedu RN. Antisense Oligonucleotides as Potential Therapeutics for Type 2 Diabetes. Nucleic Acid Ther 2020; 31:39-57. [PMID: 33026966 DOI: 10.1089/nat.2020.0891] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Type 2 diabetes (T2D) is a chronic metabolic disorder characterized by persistent hyperglycemia resulting from inefficient signaling and insufficient production of insulin. Conventional management of T2D has largely relied on small molecule-based oral hypoglycemic medicines, which do not halt the progression of the disease due to limited efficacy and induce adverse effects as well. To this end, antisense oligonucleotide has attracted immense attention in developing antidiabetic agents because of their ability to downregulate the expression of disease-causing genes at the RNA and protein level. To date, seven antisense agents have been approved by the United States Food and Drug Administration for therapies of a variety of human maladies, including genetic disorders. Herein, we provide a comprehensive review of antisense molecules developed for suppressing the causative genes believed to be responsible for insulin resistance and hyperglycemia toward preventing and treating T2D.
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Affiliation(s)
- Suxiang Chen
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, Australia.,Perron Institute for Neurological and Translational Science, Perth, Australia
| | - Nabayet Sbuh
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, Australia.,Perron Institute for Neurological and Translational Science, Perth, Australia
| | - Rakesh N Veedu
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, Australia.,Perron Institute for Neurological and Translational Science, Perth, Australia
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12
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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: 12] [Impact Index Per Article: 3.0] [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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13
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Wang Y, Wang A, Alkhalidy H, Luo J, Moomaw E, Neilson AP, Liu D. Flavone Hispidulin Stimulates Glucagon-Like Peptide-1 Secretion and Ameliorates Hyperglycemia in Streptozotocin-Induced Diabetic Mice. Mol Nutr Food Res 2020; 64:e1900978. [PMID: 31967385 DOI: 10.1002/mnfr.201900978] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/24/2019] [Indexed: 12/17/2022]
Abstract
SCOPE Loss of functional β-cell mass is central for the deterioration of glycemic control in diabetes. The incretin hormone glucagon-like peptide-1 (GLP-1) plays a critical role in maintaining glycemic homeostasis via potentiating glucose-stimulated insulin secretion and promoting β-cell mass. Agents that can directly promote GLP-1 secretion, thereby increasing insulin secretion and preserving β-cell mass, hold great potential for the treatment of T2D. METHODS AND RESULTS GluTag L-cells, INS832/13 cells, and mouse ileum crypts and islets are cultured for examining the effects of flavone hispidulin on GLP-1 and insulin secretion. Mouse livers and isolated hepatocytes are used for gluconeogenesis. Streptozotocin-induced diabetic mice are treated with hispidulin (20 mg kg-1 day-1 , oral gavage) for 6 weeks to evaluate its anti-diabetic potential. Hispidulin stimulates GLP-1 secretion from the L-cell line, ileum crypts, and in vivo. This hispidulin action is mediated via activation of cyclic adenosine monophosphate/protein kinase A signaling. Hispidulin significantly improves glycemic control in diabetic mice, concomitant with improved insulin release, and β-cell survival. Additionally, hispidulin decreases hepatic pyruvate carboxylase expression in diabetic mice and suppresses gluconeogenesis in hepatocytes. Furthermore, hispidulin stimulates insulin secretion from β-cells. CONCLUSION These findings suggest that Hispidulin may be a novel dual-action anti-diabetic compound via stimulating GLP-1 secretion and suppressing hepatic glucose production.
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Affiliation(s)
- Yao Wang
- Department of Human Nutrition, Foods, and Exercise, College of Agricultural and Life Sciences, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Aiping Wang
- College of Life Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Hana Alkhalidy
- Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Jing Luo
- Department of Human Nutrition, Foods, and Exercise, College of Agricultural and Life Sciences, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Elizabeth Moomaw
- Department of Human Nutrition, Foods, and Exercise, College of Agricultural and Life Sciences, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Andrew P Neilson
- Plants for Human Health Institution, North Carolina State University, Kannapolis, NC, 28081, USA
| | - Dongmin Liu
- Department of Human Nutrition, Foods, and Exercise, College of Agricultural and Life Sciences, Virginia Tech, Blacksburg, VA, 24060, USA
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14
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Revisiting the Pharmacological Value of Glucagon: An Editorial for the Special Issue "The Biology and Pharmacology of Glucagon". Int J Mol Sci 2020; 21:ijms21020383. [PMID: 31936192 PMCID: PMC7013494 DOI: 10.3390/ijms21020383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 11/16/2022] Open
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15
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Chabenne JR, Mroz PA, Mayer JP, DiMarchi RD. Structural Refinement of Glucagon for Therapeutic Use. J Med Chem 2019; 63:3447-3460. [PMID: 31774682 DOI: 10.1021/acs.jmedchem.9b01493] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Glucagon counters insulin's effects on glucose metabolism and serves as a rescue medicine in the treatment of hypoglycemia. Acute hypoglycemia, a common occurrence in insulin-dependent diabetes, is the central obstacle to correcting high blood glucose, a primary cause of long-term microvascular complications. As a result, there has been a resurgence of interest in improved glucagon therapy, including nonconventional liquid formulations, alternative routes of administration, and novel analogs with optimized biophysical properties. These options collectively minimize the complexity of glucagon delivery and enable its application in ways not feasible with conventional emergency rescue kits. These advances have indirectly promoted the integrated use of glucagon agonism with other hormones in a manner that runs counter to the long-standing pursuit of glucagon antagonism. This review summarizes novel approaches to glucagon optimization, methods with potential application to the broader family of therapeutic peptides, where biophysical challenges may be encountered.
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Affiliation(s)
- Joseph R Chabenne
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
| | - Piotr A Mroz
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John P Mayer
- MCD Biology, University of Colorado, Boulder, Colorado 80309, United States
| | - Richard D DiMarchi
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States.,Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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16
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Knudsen LB. Inventing Liraglutide, a Glucagon-Like Peptide-1 Analogue, for the Treatment of Diabetes and Obesity. ACS Pharmacol Transl Sci 2019; 2:468-484. [PMID: 32259078 DOI: 10.1021/acsptsci.9b00048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Indexed: 01/08/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) has been in focus since the early 1980s as a long looked for incretin hormone, released from the gastrointestinal tract and with an important effect on glucose-dependent insulin secretion, providing efficient glucose lowering, with little risk for hypoglycemia. The enzyme dipeptidyl peptidase-4 (DPP-4) degrades GLP-1 very fast, and the remaining metabolite is cleared rapidly by the kidneys. Liraglutide is a fatty acid acylated analogue of GLP-1 that provides efficacy for 24 h/day. The mechanism of action for liraglutide is reviewed in detail with focus on pancreatic efficacy and safety, thyroid safety, and weight loss mechanism. Evolving science hypothesizes that GLP-1 has important effects on atherosclerosis, relevant for the cardiovascular benefit seen in the treatment of diabetes and obesity. Also, GLP-1 may be relevant in neurodegenerative diseases.
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Affiliation(s)
- Lotte Bjerre Knudsen
- Global Drug Discovery, Novo Nordisk, Novo Nordisk Park, DK-2760 Maaloev, Denmark
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17
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The Flavonoid Kaempferol Ameliorates Streptozotocin-Induced Diabetes by Suppressing Hepatic Glucose Production. Molecules 2018; 23:molecules23092338. [PMID: 30216981 PMCID: PMC6192519 DOI: 10.3390/molecules23092338] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/04/2018] [Accepted: 09/08/2018] [Indexed: 12/20/2022] Open
Abstract
In diabetes mellitus, the excessive rate of glucose production from the liver is considered a primary contributor for the development of hyperglycemia, in particular, fasting hyperglycemia. In this study, we investigated whether kaempferol, a flavonol present in several medicinal herbs and foods, can be used to ameliorate diabetes in an animal model of insulin deficiency and further explored the mechanism underlying the anti-diabetic effect of this flavonol. We demonstrate that oral administration of kaempferol (50 mg/kg/day) to streptozotocin-induced diabetic mice significantly improved hyperglycemia and reduced the incidence of overt diabetes from 100% to 77.8%. This outcome was accompanied by a reduction in hepatic glucose production and an increase in glucose oxidation in the muscle of the diabetic mice, whereas body weight, calorie intake, body composition, and plasma insulin and glucagon levels were not altered. Consistently, treatment with kaempferol restored hexokinase activity in the liver and skeletal muscle of diabetic mice while suppressed hepatic pyruvate carboxylase activity and gluconeogenesis. These results suggest that kaempferol may exert antidiabetic action via promoting glucose metabolism in skeletal muscle and inhibiting gluconeogenesis in the liver.
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18
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Abstract
The somatostatin-secreting δ-cells comprise ~5% of the cells of the pancreatic islets. The δ-cells have complex morphology and might interact with many more islet cells than suggested by their low numbers. δ-Cells contain ATP-sensitive potassium channels, which open at low levels of glucose but close when glucose is elevated. This closure initiates membrane depolarization and electrical activity and increased somatostatin secretion. Factors released by neighbouring α-cells or β-cells amplify the glucose-induced effects on somatostatin secretion from δ-cells, which act locally within the islets as paracrine or autocrine inhibitors of insulin, glucagon and somatostatin secretion. The effects of somatostatin are mediated by activation of somatostatin receptors coupled to the inhibitory G protein, which culminates in suppression of the electrical activity and exocytosis in α-cells and β-cells. Somatostatin secretion is perturbed in animal models of diabetes mellitus, which might explain the loss of appropriate hypoglycaemia-induced glucagon secretion, a defect that could be mitigated by somatostatin receptor 2 antagonists. Somatostatin antagonists or agents that suppress somatostatin secretion have been proposed as an adjunct to insulin therapy. In this Review, we summarize the cell physiology of somatostatin secretion, what might go wrong in diabetes mellitus and the therapeutic potential of agents targeting somatostatin secretion or action.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, University of Oxford, Oxford, UK.
- Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
| | - Mark O Huising
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, USA
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19
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The somatostatin-secreting pancreatic δ-cell in health and disease. NATURE REVIEWS. ENDOCRINOLOGY 2018. [PMID: 29773871 DOI: 10.1038/s41574‐018‐0020‐6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The somatostatin-secreting δ-cells comprise ~5% of the cells of the pancreatic islets. The δ-cells have complex morphology and might interact with many more islet cells than suggested by their low numbers. δ-Cells contain ATP-sensitive potassium channels, which open at low levels of glucose but close when glucose is elevated. This closure initiates membrane depolarization and electrical activity and increased somatostatin secretion. Factors released by neighbouring α-cells or β-cells amplify the glucose-induced effects on somatostatin secretion from δ-cells, which act locally within the islets as paracrine or autocrine inhibitors of insulin, glucagon and somatostatin secretion. The effects of somatostatin are mediated by activation of somatostatin receptors coupled to the inhibitory G protein, which culminates in suppression of the electrical activity and exocytosis in α-cells and β-cells. Somatostatin secretion is perturbed in animal models of diabetes mellitus, which might explain the loss of appropriate hypoglycaemia-induced glucagon secretion, a defect that could be mitigated by somatostatin receptor 2 antagonists. Somatostatin antagonists or agents that suppress somatostatin secretion have been proposed as an adjunct to insulin therapy. In this Review, we summarize the cell physiology of somatostatin secretion, what might go wrong in diabetes mellitus and the therapeutic potential of agents targeting somatostatin secretion or action.
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20
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Meek TH, Matsen ME, Faber CL, Samstag CL, Damian V, Nguyen HT, Scarlett JM, Flak JN, Myers MG, Morton GJ. In Uncontrolled Diabetes, Hyperglucagonemia and Ketosis Result From Deficient Leptin Action in the Parabrachial Nucleus. Endocrinology 2018; 159:1585-1594. [PMID: 29438473 PMCID: PMC5939636 DOI: 10.1210/en.2017-03199] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/25/2018] [Indexed: 12/17/2022]
Abstract
Growing evidence implicates neurons that project from the lateral parabrachial nucleus (LPBN) to the hypothalamic ventromedial nucleus (VMN) in a neurocircuit that drives counterregulatory responses to hypoglycemia, including increased glucagon secretion. Among LPBN neurons in this circuit is a subset that expresses cholecystokinin (LPBNCCK neurons) and is tonically inhibited by leptin. Because uncontrolled diabetes is associated with both leptin deficiency and hyperglucagonemia, and because intracerebroventricular (ICV) leptin administration reverses both hyperglycemia and hyperglucagonemia in this setting, we hypothesized that deficient leptin inhibition of LPBNCCK neurons drives activation of this LPBN→VMN circuit and thereby results in hyperglucagonemia. Here, we report that although bilateral microinjection of leptin into the LPBN does not ameliorate hyperglycemia in rats with streptozotocin-induced diabetes mellitus (STZ-DM), it does attenuate the associated hyperglucagonemia and ketosis. To determine if LPBN leptin signaling is required for the antidiabetic effect of ICV leptin in STZ-DM, we studied mice in which the leptin receptor was selectively deleted from LPBNCCK neurons. Our findings show that although leptin signaling in these neurons is not required for the potent antidiabetic effect of ICV leptin, it is required for leptin-mediated suppression of diabetic hyperglucagonemia. Taken together, these findings suggest that leptin-mediated effects in animals with uncontrolled diabetes occur through actions involving multiple brain areas, including the LPBN, where leptin acts specifically to inhibit glucagon secretion and associated ketosis.
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Affiliation(s)
- Thomas H Meek
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Miles E Matsen
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Chelsea L Faber
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Colby L Samstag
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Vincent Damian
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Hong T Nguyen
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Jarrad M Scarlett
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
| | - Jonathan N Flak
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Martin G Myers
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Gregory J Morton
- University of Washington Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington
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21
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Baldari S, Garufi A, Granato M, Cuomo L, Pistritto G, Cirone M, D'Orazi G. Hyperglycemia triggers HIPK2 protein degradation. Oncotarget 2018; 8:1190-1203. [PMID: 27901482 PMCID: PMC5352047 DOI: 10.18632/oncotarget.13595] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/08/2016] [Indexed: 12/23/2022] Open
Abstract
Homeodomain interacting protein kinase-2 (HIPK2) is an evolutionary conserved kinase that modulates several key molecular pathways to restrain tumor growth and induce p53-depending apoptotic cell-death in response to anticancer therapies. HIPK2 silencing in cancer cells leads to chemoresistance and cancer progression, in part due to p53 inhibition. Recently, hyperglycemia has been shown to reduce p53 phosphorylation at serine 46 (Ser46), the target residue of HIPK2, thus impairing p53 apoptotic function. Here we asked whether hyperglycemia could, upstream of p53, target HIPK2. We focused on the effect of high glucose (HG) on HIPK2 protein stability and the underlying mechanisms. We found that HG reduced HIPK2 protein levels, therefore impairing HIPK2-induced p53 apoptotic activity. HG-triggered HIPK2 protein downregulation was rescued by both proteasome inhibitor MG132 and by protein phosphatase inhibitors Calyculin A (CL-A) and Okadaic Acid (OA). Looking for the phosphatase involved, we found that protein phosphatase 2A (PP2A) induced HIPK2 degradation, as evidenced by directly activating PP2A with FTY720 or by silencing PP2A with siRNA in HG condition. The effect of PP2A on HIPK2 protein degradation could be in part due to hypoxia-inducible factor-1 (HIF-1) activity which has been previously shown to induce HIPK2 proteasomal degradation through several ubiquitin ligases. Validation analysed performed with HIF-1α dominant negative or with silencing of Siah2 ubiquitin ligase clearly showed rescue of HG-induced HIPK2 degradation. These findings demonstrate how hyperglycemia, through a complex protein cascade, induced HIPK2 downregulation and consequently impaired p53 apoptotic activity, revealing a novel link between diabetes/obesity and tumor resistance to therapies.
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Affiliation(s)
- Silvia Baldari
- Department of Research, Advanced Diagnostics, and Technological Innovation, Regina Elena National Cancer Institute, 00144 Rome, Italy
| | - Alessia Garufi
- Department of Research, Advanced Diagnostics, and Technological Innovation, Regina Elena National Cancer Institute, 00144 Rome, Italy.,Department of Medical Sciences, Tumor Biology Unit, University 'G. d'Annunzio', 66013 Chieti, Italy
| | - Marisa Granato
- Department of Experimental Medicine, Pasteur-Fondazione Cenci Bolognetti Institute, Sapienza University, 00100 Rome, Italy
| | - Laura Cuomo
- U.O.C. Clinical Pathology, A.C.O., San Filippo Neri Hospital, 00100 Rome, Italy
| | - Giuseppa Pistritto
- Department of Systems Medicine, University Tor Vergata, 00133 Rome, Italy
| | - Mara Cirone
- Department of Experimental Medicine, Pasteur-Fondazione Cenci Bolognetti Institute, Sapienza University, 00100 Rome, Italy
| | - Gabriella D'Orazi
- Department of Research, Advanced Diagnostics, and Technological Innovation, Regina Elena National Cancer Institute, 00144 Rome, Italy.,Department of Medical Sciences, Tumor Biology Unit, University 'G. d'Annunzio', 66013 Chieti, Italy
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22
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Hyperglycemia and aberrant O-GlcNAcylation: contributions to tumor progression. J Bioenerg Biomembr 2018; 50:175-187. [DOI: 10.1007/s10863-017-9740-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 12/26/2017] [Indexed: 12/17/2022]
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23
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Banno Y, Sasaki S, Kamata M, Kunitomo J, Miyamoto Y, Abe H, Taya N, Oi S, Watanabe M, Urushibara T, Hazama M, Niwa SI, Miyamoto S, Horinouchi A, Kuroshima KI, Amano N, Matsumoto SI, Matsunaga S. Design and synthesis of a novel series of orally active, selective somatostatin receptor 2 agonists for the treatment of type 2 diabetes. Bioorg Med Chem 2017; 25:5995-6006. [DOI: 10.1016/j.bmc.2017.09.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/19/2017] [Accepted: 09/19/2017] [Indexed: 11/25/2022]
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24
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Müller TD, Finan B, Clemmensen C, DiMarchi RD, Tschöp MH. The New Biology and Pharmacology of Glucagon. Physiol Rev 2017; 97:721-766. [PMID: 28275047 DOI: 10.1152/physrev.00025.2016] [Citation(s) in RCA: 206] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the last two decades we have witnessed sizable progress in defining the role of gastrointestinal signals in the control of glucose and energy homeostasis. Specifically, the molecular basis of the huge metabolic benefits in bariatric surgery is emerging while novel incretin-based medicines based on endogenous hormones such as glucagon-like peptide 1 and pancreas-derived amylin are improving diabetes management. These and related developments have fostered the discovery of novel insights into endocrine control of systemic metabolism, and in particular a deeper understanding of the importance of communication across vital organs, and specifically the gut-brain-pancreas-liver network. Paradoxically, the pancreatic peptide glucagon has reemerged in this period among a plethora of newly identified metabolic macromolecules, and new data complement and challenge its historical position as a gut hormone involved in metabolic control. The synthesis of glucagon analogs that are biophysically stable and soluble in aqueous solutions has promoted biological study that has enriched our understanding of glucagon biology and ironically recruited glucagon agonism as a central element to lower body weight in the treatment of metabolic disease. This review summarizes the extensive historical record and the more recent provocative direction that integrates the prominent role of glucagon in glucose elevation with its under-acknowledged effects on lipids, body weight, and vascular health that have implications for the pathophysiology of metabolic diseases, and the emergence of precision medicines to treat metabolic diseases.
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Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - B Finan
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - C Clemmensen
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - R D DiMarchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - M H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Department of Chemistry, Indiana University, Bloomington, Indiana; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
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25
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LIMA LUÍSM. Subclinical Diabetes. ACTA ACUST UNITED AC 2017; 89:591-614. [DOI: 10.1590/0001-3765201720160394] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Accepted: 09/20/2016] [Indexed: 12/15/2022]
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26
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Lee YH, Wang MY, Yu XX, Unger RH. Glucagon is the key factor in the development of diabetes. Diabetologia 2016; 59:1372-1375. [PMID: 27115412 DOI: 10.1007/s00125-016-3965-9] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 03/18/2016] [Indexed: 12/22/2022]
Abstract
Glucagon plays important roles in normal glucose homeostasis and in metabolic abnormalities, particularly diabetes. Glucagon excess, rather than insulin deficiency, is essential for the development of diabetes for several reasons. Glucagon increases hepatic glucose and ketone production, the catabolic features of insulin deficiency. Hyperglucagonaemia is present in every form of diabetes. Beta cell destruction in glucagon receptor null mice does not cause diabetes unless mice are administered adenovirus encoding the glucagon receptor. In rodent studies the glucagon suppressors leptin and glucagon receptor antibody suppressed all catabolic manifestations of diabetes during insulin deficiency. Insulin prevents hyperglycaemia; however, insulin monotherapy cannot cure diabetes such that non-diabetic glucose homeostasis is achieved. Glucose-responsive beta cells normally regulate alpha cells, and diminished insulin action on alpha cells will favour hypersecretion of glucagon by the alpha cells, thus altering the insulin:glucagon ratio. Treating diabetes by suppression of glucagon, with leptin or antibody against the glucagon receptor, normalised glucose level (without glycaemic volatility) and HbA1c. Glucagon suppression also improved insulin sensitivity and glucose tolerance. If these results can be translated to humans, suppression of glucagon action will represent a step forward in the treatment of diabetes. This review summarises a presentation given at the 'Novel data on glucagon' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Mona Abraham and Tony Lam, DOI: 10.1007/s00125-016-3950-3 , and by Russell Miller and Morris Birnbaum, DOI: 10.1007/s00125-016-3955-y ) and an overview by the Session Chair, Isabel Valverde (DOI: 10.1007/s00125-016-3946-z ).
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Affiliation(s)
- Young H Lee
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
| | - May-Yun Wang
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Xin-Xin Yu
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Roger H Unger
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
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27
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Garufi A, Trisciuoglio D, Cirone M, D'Orazi G. ZnCl2 sustains the adriamycin-induced cell death inhibited by high glucose. Cell Death Dis 2016; 7:e2280. [PMID: 27362798 PMCID: PMC5108333 DOI: 10.1038/cddis.2016.178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/14/2016] [Accepted: 05/30/2016] [Indexed: 12/15/2022]
Abstract
Hyperglycemia, the condition of high blood glucose, is typical of diabetes and obesity and represents a significant clinical problem. The relationship between hyperglycemia and cancer risk has been established by several studies. Moreover, hyperglycemia has been shown to reduce cancer cell response to therapies, conferring resistance to drug-induced cell death. Therefore, counteracting the negative effects of hyperglycemia may positively improve the cancer cell death induced by chemotherapies. Recent studies showed that zinc supplementation may have beneficial effects on glycemic control. Here we aimed at evaluating whether ZnCl2 could counteract the high-glucose (HG) effects and consequently restore the drug-induced cancer cell death. At the molecular level we found that the HG-induced expression of genes known to be involved in chemoresistance (such as HIF-1α, GLUT1, and HK2 glycolytic genes, as well as NF-κB activity) was reduced by ZnCl2 treatment. In agreement, the adryamicin (ADR)-induced apoptotic cancer cell death was significantly impaired by HG and efficiently re-established by ZnCl2 cotreatment. Mechanistically, the ADR-induced c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) phosphorylation, inhibited by HG, was efficiently restored by ZnCl2. The JNK involvement in apoptotic cell death was assessed by the use of JNK dominant-negative expression vector that indeed impaired the ZnCl2 ability to restore drug-induced cell death in HG condition. Altogether, these findings indicate that ZnCl2 supplementation efficiently restored the drug-induced cancer cell death, inhibited by HG, by both sustaining JNK activation and counteracting the glycolytic pathway.
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Affiliation(s)
- A Garufi
- Department of Research, Advanced Diagnostics, and Technological Innovation, Regina Elena National Cancer Institute, Rome, Italy.,Department of Medical, Oral and Biotechnological Sciences, Tumor Biology Section, University 'G. d'Annunzio', Chieti, Italy
| | - D Trisciuoglio
- Department of Research, Advanced Diagnostics, and Technological Innovation, Regina Elena National Cancer Institute, Rome, Italy
| | - M Cirone
- Department of Experimental Medicine, Pasteur-Fondazione Cenci Bolognetti Institute, Sapienza University, Rome, Italy
| | - G D'Orazi
- Department of Research, Advanced Diagnostics, and Technological Innovation, Regina Elena National Cancer Institute, Rome, Italy.,Department of Medical, Oral and Biotechnological Sciences, Tumor Biology Section, University 'G. d'Annunzio', Chieti, Italy
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28
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Abstract
While it is well established that the adiposity hormone leptin plays a key role in the regulation of energy homeostasis, growing evidence suggests that leptin is also critical for glycaemic control. In this review we examine the role of the brain in the glucose-lowering actions of leptin and the potential mediators responsible for driving hyperglycaemia in states of uncontrolled insulin-deficient diabetes (uDM). These considerations highlight the possibility of targeting leptin-sensitive pathways as a therapeutic option for the treatment of diabetes. This review summarises a presentation given at the 'Is leptin coming back?' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Christoffer Clemmensen and colleagues, DOI: 10.1007/s00125-016-3906-7 , and by Gerald Shulman and colleagues, DOI: 10.1007/s00125-016-3909-4 ) and an overview by the Session Chair, Ulf Smith (DOI: 10.1007/s00125-016-3894-7 ).
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Affiliation(s)
- Thomas H Meek
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington at South Lake Union, 850 Republican St., N335, Box 358055, Seattle, WA, 98195, USA
| | - Gregory J Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington at South Lake Union, 850 Republican St., N335, Box 358055, Seattle, WA, 98195, USA.
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29
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Meek TH, Dorfman MD, Matsen ME, Fischer JD, Cubelo A, Kumar MR, Taborsky GJ, Morton GJ. Evidence That in Uncontrolled Diabetes, Hyperglucagonemia Is Required for Ketosis but Not for Increased Hepatic Glucose Production or Hyperglycemia. Diabetes 2015; 64:2376-87. [PMID: 25633417 PMCID: PMC4477352 DOI: 10.2337/db14-1562] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 01/24/2015] [Indexed: 12/16/2022]
Abstract
Several lines of evidence implicate excess glucagon secretion in the elevated rates of hepatic glucose production (HGP), hyperglycemia, and ketosis characteristic of uncontrolled insulin-deficient diabetes (uDM), but whether hyperglucagonemia is required for hyperglycemia in this setting is unknown. To address this question, adult male Wistar rats received either streptozotocin (STZ) to induce uDM (STZ-DM) or vehicle and remained nondiabetic. Four days later, animals received daily subcutaneous injections of either the synthetic GLP-1 receptor agonist liraglutide in a dose-escalating regimen to reverse hyperglucagonemia or its vehicle for 10 days. As expected, plasma glucagon levels were elevated in STZ-DM rats, and although liraglutide treatment lowered glucagon levels to those of nondiabetic controls, it failed to attenuate diabetic hyperglycemia, elevated rates of glucose appearance (Ra), or increased hepatic gluconeogenic gene expression. In contrast, it markedly reduced levels of both plasma ketone bodies and hepatic expression of the rate-limiting enzyme involved in ketone body production. To independently confirm this finding, in a separate study, treatment of STZ-DM rats with a glucagon-neutralizing antibody was sufficient to potently lower plasma ketone bodies but failed to normalize elevated levels of either blood glucose or Ra. These data suggest that in rats with uDM, hyperglucagonemia is required for ketosis but not for increased HGP or hyperglycemia.
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Affiliation(s)
- Thomas H Meek
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
| | - Mauricio D Dorfman
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
| | - Miles E Matsen
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
| | - Jonathan D Fischer
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
| | - Alexis Cubelo
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
| | - Monica R Kumar
- University of South Alabama College of Medicine, Mobile, AL
| | - Gerald J Taborsky
- VA Puget Sound Health Care System, Department of Veterans Affairs Medical Center, Seattle, WA
| | - Gregory J Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
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30
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Abstract
Glucagon is secreted from islet α cells and controls blood levels of glucose in the fasting state. Impaired glucagon secretion predisposes some patients with type 1 diabetes mellitus (T1DM) to hypoglycaemia; whereas hyperglycaemia in patients with T1DM or type 2 diabetes mellitus (T2DM) is often associated with hyperglucagonaemia. Hence, therapeutic strategies to safely achieve euglycaemia in patients with diabetes mellitus now encompass bihormonal approaches to simultaneously deliver insulin and glucagon (in patients with T1DM) or reduce excess glucagon action (in patients with T1DM or T2DM). Glucagon also reduces food intake and increases energy expenditure through central and peripheral mechanisms, which suggests that activation of signalling through the glucagon receptor might be useful for controlling body weight. Here, we review new data that is relevant to understanding α-cell biology and glucagon action in the brain, liver, adipose tissue and heart, with attention to normal physiology, as well as conditions associated with dysregulated glucagon action. The feasibility and safety of current and emerging glucagon-based therapies that encompass both gain-of-function and loss-of-function approaches for the treatment of T1DM, T2DM and obesity is discussed in addition to developments, challenges and critical gaps in our knowledge that require additional investigation.
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Affiliation(s)
- Jonathan E Campbell
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, 600 University Avenue, TCP5-1004, Toronto, ON M5G 1X5, Canada
| | - Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, 600 University Avenue, TCP5-1004, Toronto, ON M5G 1X5, Canada
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31
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Meek TH, Matsen ME, Damian V, Cubelo A, Chua SC, Morton GJ. Role of melanocortin signaling in neuroendocrine and metabolic actions of leptin in male rats with uncontrolled diabetes. Endocrinology 2014; 155:4157-67. [PMID: 25137027 PMCID: PMC4197991 DOI: 10.1210/en.2014-1169] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although the antidiabetic effects of leptin require intact neuronal melanocortin signaling in rodents with uncontrolled diabetes (uDM), increased melanocortin signaling is not sufficient to mimic leptin's glucose-lowering effects. The current studies were undertaken to clarify the role of melanocortin signaling in leptin's ability to correct metabolic and neuroendocrine disturbances associated with uDM. To accomplish this, bilateral cannulae were implanted in the lateral ventricle of rats with streptozotocin-induced diabetes, and leptin was coinfused with varying doses of the melanocortin 3/4 receptor (MC3/4R) antagonist, SHU9119. An additional cohort of streptozotocin-induced diabetes rats received intracerebroventricular administration of either the MC3/4R agonist, melanotan-II, or its vehicle. Consistent with previous findings, leptin's glucose-lowering effects were blocked by intracerebroventricular SHU9119. In contrast, leptin-mediated suppression of hyperglucagonemia involves both melanocortin dependent and independent mechanisms, and the degree of glucagon inhibition was associated with reduced plasma ketone body levels. Increased central nervous system melanocortin signaling alone fails to mimic leptin's ability to correct any of the metabolic or neuroendocrine disturbances associated with uDM. Moreover, the inability of increased melanocortin signaling to lower diabetic hyperglycemia does not appear to be secondary to release of the endogenous MC3/4R inverse agonist, Agouti-related peptide (AgRP), because AgRP knockout mice did not show increased susceptibility to the antidiabetic effects of increased MC3/4R signaling. Overall, these data suggest that 1) AgRP is not a major driver of diabetic hyperglycemia, 2) mechanisms independent of melanocortin signaling contribute to leptin's antidiabetic effects, and 3) melanocortin receptor blockade dissociates leptin's glucose-lowering effect from its action on other features of uDM, including reversal of hyperglucagonemia and ketosis, suggesting that brain control of ketosis, but not blood glucose levels, is glucagon dependent.
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Affiliation(s)
- Thomas H Meek
- Diabetes and Obesity Center of Excellence (T.H.M., M.E.M.,. V.D., A.C., G.J.M.), Department of Medicine, University of Washington, Seattle, Washington 98109; and Division of Endocrinology (S.C.C.), Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
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32
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Abstract
The fat‐derived hormone, leptin, is well known to regulate body weight. However, there is now substantial evidence that leptin also plays a primary role in the regulation of glucose homeostasis, independent of actions on food intake, energy expenditure or body weight. As such, leptin might have clinical utility in treating hyperglycemia, particularly in conditions of leptin deficiency, such as lipodystrophy and diabetes mellitus. The mechanisms through which leptin modulates glucose metabolism have not been fully elucidated. Leptin receptors are widely expressed in peripheral tissues, including the endocrine pancreas, liver, skeletal muscle and adipose, and both direct and indirect leptin action on these tissues contributes to the control of glucose homeostasis. Here we review the role of leptin in glucose homeostasis, along with our present understanding of the mechanisms involved. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00203.x, 2012)
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Affiliation(s)
- Heather C Denroche
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, The Life Sciences Institute ; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
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33
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Hyperglycemia, a neglected factor during cancer progression. BIOMED RESEARCH INTERNATIONAL 2014; 2014:461917. [PMID: 24864247 PMCID: PMC4016871 DOI: 10.1155/2014/461917] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/17/2014] [Accepted: 02/17/2014] [Indexed: 12/11/2022]
Abstract
Recent evidence from large cohort studies suggests that there exists a higher cancer incidence in people with type 2 diabetes (DM2). However, to date, the potential reasons for this association remain unclear. Hyperglycemia, the most important feature of diabetes, may be responsible for the excess glucose supply for these glucose-hungry cells, and it contributes to apoptosis resistance, oncogenesis, and tumor cell resistance to chemotherapy. Considering associations between diabetes and malignancies, the effect of hyperglycemia on cancer progression in cancer patients with abnormal blood glucose should not be neglected. In this paper, we describe the role that hyperglycemia plays in cancer progression and treatment and illustrate that hyperglycemia may contribute to a more malignant phenotype of cancer cells and lead to drug resistance. Therefore, controlling hyperglycemia may have important therapeutic implications in cancer patients.
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Omar BA, Andersen B, Hald J, Raun K, Nishimura E, Ahrén B. Fibroblast growth factor 21 (FGF21) and glucagon-like peptide 1 contribute to diabetes resistance in glucagon receptor-deficient mice. Diabetes 2014; 63:101-10. [PMID: 24062250 DOI: 10.2337/db13-0710] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mice genetically deficient in the glucagon receptor (Gcgr(-/-)) show improved glucose tolerance, insulin sensitivity, and α-cell hyperplasia. In addition, Gcgr(-/-) mice do not develop diabetes after chemical destruction of β-cells. Since fibroblast growth factor 21 (FGF21) has insulin-independent glucose-lowering properties, we investigated whether FGF21 was contributing to diabetes resistance in insulin-deficient Gcgr(-/-) mice. Plasma FGF21 was 25-fold higher in Gcgr(-/-) mice than in wild-type mice. FGF21 was found to be expressed in pancreatic β- and α-cells, with high expression in the hyperplastic α-cells of Gcgr(-/-) mice. FGF21 expression was also significantly increased in liver and adipose tissue of Gcgr(-/-) mice. To investigate the potential antidiabetic actions of FGF21 in insulin-deficient Gcgr(-/-) mice, an FGF21-neutralizing antibody was administered prior to oral glucose tolerance tests (OGTTs). FGF21 neutralization caused a decline in glucose tolerance in insulin-deficient Gcgr(-/-) mice during the OGTT. Despite this decline, insulin-deficient Gcgr(-/-) mice did not develop hyperglycemia. Glucagon-like peptide 1 (GLP-1) also has insulin-independent glucose-lowering properties, and an elevated circulating level of GLP-1 is a known characteristic of Gcgr(-/-) mice. Neutralization of FGF21, while concurrently blocking the GLP-1 receptor with the antagonist Exendin 9-39 (Ex9-39), resulted in significant hyperglycemia in insulin-deficient Gcgr(-/-) mice, while blocking with Ex9-39 alone did not. In conclusion, FGF21 acts additively with GLP-1 to prevent insulinopenic diabetes in mice lacking glucagon action.
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Affiliation(s)
- Bilal A Omar
- Department of Clinical Sciences, Lund University, Lund, Sweden
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35
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Liu S, Kilic G, Meyers MS, Navarro G, Wang Y, Oberholzer J, Mauvais-Jarvis F. Oestrogens improve human pancreatic islet transplantation in a mouse model of insulin deficient diabetes. Diabetologia 2013; 56:370-81. [PMID: 23132340 PMCID: PMC3536964 DOI: 10.1007/s00125-012-2764-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/12/2012] [Indexed: 01/01/2023]
Abstract
AIMS/HYPOTHESIS Pancreatic islet transplantation (PIT) offers a physiological treatment for type 1 diabetes, but the failure of islet engraftment hinders its application. The female hormone 17β-oestradiol (E2) favours islet survival and stimulates angiogenesis, raising the possibility that E2 may enhance islet engraftment following PIT. METHODS To explore this hypothesis, we used an insulin-deficient model with xenotransplantation of a marginal dose of human islets in nude mice rendered diabetic with streptozotocin. This was followed by 4 weeks of treatment with vehicle, E2, the non-feminising oestrogen 17α-oestradiol (17α-E2), the oestrogen receptor (ER) α agonist propyl-pyrazole-triol (PPT), the ERβ agonist diarylpropionitrile (DPN) or the G protein-coupled oestrogen receptor (GPER) agonist G1. RESULTS Treatment with E2, 17α-E2, PPT, DPN or G1 acutely improved blood glucose and eventually promoted islet engraftment, thus reversing diabetes. The effects of E2 were retained in the presence of immunosuppression and persisted after discontinuation of E2 treatment. E2 produced an acute decrease in graft hypoxic damage and suppressed beta cell apoptosis. E2 also acutely suppressed hyperglucagonaemia without altering insulin secretion, leading to normalisation of blood glucose. CONCLUSIONS/INTERPRETATION During PIT, E2 synergistic actions contribute to enhancing human islet-graft survival, revascularisation and functional mass. This study identifies E2 as a short-term treatment to improve PIT.
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Affiliation(s)
- S. Liu
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Tarry 15-761, Chicago, IL 60611 USA
- Present Address: Diabetes Institute, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - G. Kilic
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Tarry 15-761, Chicago, IL 60611 USA
| | - M. S. Meyers
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Tarry 15-761, Chicago, IL 60611 USA
| | - G. Navarro
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Tarry 15-761, Chicago, IL 60611 USA
| | - Y. Wang
- Department of Surgery, Division of Transplant Surgery, University of Illinois at Chicago, Chicago, IL USA
| | - J. Oberholzer
- Department of Surgery, Division of Transplant Surgery, University of Illinois at Chicago, Chicago, IL USA
| | - F. Mauvais-Jarvis
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Tarry 15-761, Chicago, IL 60611 USA
- Northwestern Comprehensive Center on Obesity, Northwestern University Feinberg School of Medicine, Chicago, IL USA
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36
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Abstract
Diabetes is a major worldwide problem. Despite some progress in the development of new antidiabetic agents, the ability to maintain tight glycemic control in order to prevent renal, retinal, and neuropathic complications of diabetes without adverse complications still remains a challenge. Recent evidence suggests, however, that in addition to playing a key role in the regulation of energy homeostasis, the adiposity hormone leptin also plays an important role in the control of glucose metabolism via its actions in the brain. This review examines the role of leptin action in the central nervous system and the mechanisms whereby leptin mediates its effects to regulate glucose metabolism. These findings suggest that defects or dysfunction in leptin signaling may contribute to the etiology of diabetes and raise the possibility that either leptin or downstream targets of leptin may have therapeutic potential for the treatment of diabetes.
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Affiliation(s)
- Thomas H. Meek
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Gregory J. Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA, USA
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37
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Wu G, Zhang L, Li T, Zuniga A, Lopaschuk GD, Li L, Jacobs RL, Vance DE. Choline supplementation promotes hepatic insulin resistance in phosphatidylethanolamine N-methyltransferase-deficient mice via increased glucagon action. J Biol Chem 2012. [PMID: 23179947 DOI: 10.1074/jbc.m112.415117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Biosynthesis of hepatic choline via phosphatidylethanolamine N-methyltransferase (PEMT) plays an important role in the development of type 2 diabetes and obesity. We investigated the mechanism(s) by which choline modulates insulin sensitivity. PEMT wild-type (Pemt(+/+)) and knock-out (Pemt(-/-)) mice received either a high fat diet (HF; 60% kcal of fat) or a high fat, high choline diet (HFHC; 4 g of choline/kg of HF diet) for 1 week. Hepatic insulin signaling and glucose and lipid homeostasis were investigated. Glucose and insulin intolerance occurred in Pemt(-/-) mice fed the HFHC diet, but not in their Pemt(-/-) littermates fed the HF diet. Plasma glucagon was elevated in Pemt(-/-) mice fed the HFHC diet compared with Pemt(-/-) mice fed the HF diet, concomitant with increased hepatic expression of glucagon receptor, phosphorylated AMP-activated protein kinase (AMPK), and phosphorylated insulin receptor substrate 1 at serine 307 (IRS1-s307). Gluconeogenesis and mitochondrial oxidative stress were markedly enhanced, whereas glucose oxidation and triacylglycerol biosynthesis were diminished in Pemt(-/-) mice fed the HFHC diet. A glucagon receptor antagonist (2-aminobenzimidazole) attenuated choline-induced hyperglycemia and insulin intolerance and blunted up-regulation of phosphorylated AMPK and IRS1-s307. Choline induces glucose and insulin intolerance in Pemt(-/-) mice through modulating plasma glucagon and its action in liver.
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Affiliation(s)
- Gengshu Wu
- Group on the Molecular and Cell Biology of Lipids and Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
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38
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Metabolic manifestations of insulin deficiency do not occur without glucagon action. Proc Natl Acad Sci U S A 2012; 109:14972-6. [PMID: 22891336 DOI: 10.1073/pnas.1205983109] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
To determine unambiguously if suppression of glucagon action will eliminate manifestations of diabetes, we expressed glucagon receptors in livers of glucagon receptor-null (GcgR(-/-)) mice before and after β-cell destruction by high-dose streptozotocin. Wild type (WT) mice developed fatal diabetic ketoacidosis after streptozotocin, whereas GcgR(-/-) mice with similar β-cell destruction remained clinically normal without hyperglycemia, impaired glucose tolerance, or hepatic glycogen depletion. Restoration of receptor expression using adenovirus containing the GcgR cDNA restored hepatic GcgR, phospho-cAMP response element binding protein (P-CREB), and phosphoenol pyruvate carboxykinase, markers of glucagon action, rose dramatically and severe hyperglycemia appeared. When GcgR mRNA spontaneously disappeared 7 d later, P-CREB declined and hyperglycemia disappeared. In conclusion, the metabolic manifestations of diabetes cannot occur without glucagon action and, once present, disappear promptly when glucagon action is abolished. Glucagon suppression should be a major therapeutic goal in diabetes.
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Chen L, Philippe J, Unger RH. Glucagon responses of isolated α cells to glucose, insulin, somatostatin, and leptin. Endocr Pract 2012; 17:819-25. [PMID: 21940282 DOI: 10.4158/ep11101.or] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE To determine whether glucagon suppression by leptin represents a direct effect on α cells rather than an indirect effect mediated via the hypothalamus. METHODS We devised an in vitro α-cell suppression assay in cultured hamster InR1G9 cells. InR1G9 hamster cells were infected with adenovirus containing mouse leptin receptors, and they were then incubated with leptin, insulin, or somatostatin in concentrations known to suppress glucagon in vivo. RESULTS Whereas somatostatin and insulin both suppressed the increase in glucagon secretion stimulated by high levels of glucose, leptin had no such effect. This inability of leptin to suppress glucagon in vitro could signify that it acts indirectly by causing the release of glucagon-suppressing peptides from the hypothalamus or stomach. To search for such a peptide, we studied the effects on glucagon secretion of 6 neuropeptides: orexin, melanocyte-stimulating hormone, neuropeptide Y, cocaine and amphetamine regulated transcript, neurotensin, and Agouti-related peptide that might be involved in the hypothalamic action of leptin. None of these peptides suppressed glucagon at low, normal, or elevated glucose concentrations. CONCLUSIONS If the cultured α cells used faithfully mimic the leptin response of in situ α cells of the diabetic animal, the glucagon-suppressing action of leptin is indirect, but is not mediated by any 1 of the 6 neuropeptides tested.
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Affiliation(s)
- Lijun Chen
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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40
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Unger RH, Cherrington AD. Glucagonocentric restructuring of diabetes: a pathophysiologic and therapeutic makeover. J Clin Invest 2012; 122:4-12. [PMID: 22214853 DOI: 10.1172/jci60016] [Citation(s) in RCA: 497] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The hormone glucagon has long been dismissed as a minor contributor to metabolic disease. Here we propose that glucagon excess, rather than insulin deficiency, is the sine qua non of diabetes. We base this on the following evidence: (a) glucagon increases hepatic glucose and ketone production, catabolic features present in insulin deficiency; (b) hyperglucagonemia is present in every form of poorly controlled diabetes; (c) the glucagon suppressors leptin and somatostatin suppress all catabolic manifestations of diabetes during total insulin deficiency; (d) total β cell destruction in glucagon receptor-null mice does not cause diabetes; and (e) perfusion of normal pancreas with anti-insulin serum causes marked hyperglucagonemia. From this and other evidence, we conclude that glucose-responsive β cells normally regulate juxtaposed α cells and that without intraislet insulin, unregulated α cells hypersecrete glucagon, which directly causes the symptoms of diabetes. This indicates that glucagon suppression or inactivation may provide therapeutic advantages over insulin monotherapy.
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Affiliation(s)
- Roger H Unger
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8854, USA.
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41
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Robson-Doucette CA, Sultan S, Allister EM, Wikstrom JD, Koshkin V, Bhatacharjee A, Prentice KJ, Sereda SB, Shirihai OS, Wheeler MB. Beta-cell uncoupling protein 2 regulates reactive oxygen species production, which influences both insulin and glucagon secretion. Diabetes 2011; 60:2710-9. [PMID: 21984579 PMCID: PMC3198081 DOI: 10.2337/db11-0132] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The role of uncoupling protein 2 (UCP2) in pancreatic β-cells is highly debated, partly because of the broad tissue distribution of UCP2 and thus limitations of whole-body UCP2 knockout mouse models. To investigate the function of UCP2 in the β-cell, β-cell-specific UCP2 knockout mice (UCP2BKO) were generated and characterized. RESEARCH DESIGN AND METHODS UCP2BKO mice were generated by crossing loxUCP2 mice with mice expressing rat insulin promoter-driven Cre recombinase. Several in vitro and in vivo parameters were measured, including respiration rate, mitochondrial membrane potential, islet ATP content, reactive oxygen species (ROS) levels, glucose-stimulated insulin secretion (GSIS), glucagon secretion, glucose and insulin tolerance, and plasma hormone levels. RESULTS UCP2BKO β-cells displayed mildly increased glucose-induced mitochondrial membrane hyperpolarization but unchanged rates of uncoupled respiration and islet ATP content. UCP2BKO islets had elevated intracellular ROS levels that associated with enhanced GSIS. Surprisingly, UCP2BKO mice were glucose-intolerant, showing greater α-cell area, higher islet glucagon content, and aberrant ROS-dependent glucagon secretion under high glucose conditions. CONCLUSIONS Using a novel β-cell-specific UCP2KO mouse model, we have shed light on UCP2 function in primary β-cells. UCP2 does not behave as a classical metabolic uncoupler in the β-cell, but has a more prominent role in the regulation of intracellular ROS levels that contribute to GSIS amplification. In addition, β-cell UCP2 contributes to the regulation of intraislet ROS signals that mediate changes in α-cell morphology and glucagon secretion.
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Affiliation(s)
| | - Sobia Sultan
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Emma M. Allister
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jakob D. Wikstrom
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts
- The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Vasilij Koshkin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | | | - Kacey J. Prentice
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Samuel B. Sereda
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Orian S. Shirihai
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Michael B. Wheeler
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Corresponding author: Michael B. Wheeler,
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42
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Morton GJ, Schwartz MW. Leptin and the central nervous system control of glucose metabolism. Physiol Rev 2011; 91:389-411. [PMID: 21527729 DOI: 10.1152/physrev.00007.2010] [Citation(s) in RCA: 210] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The regulation of body fat stores and blood glucose levels is critical for survival. This review highlights growing evidence that leptin action in the central nervous system plays a key role in both processes. Investigation into underlying mechanisms has begun to clarify the physiological role of leptin in the control of glucose metabolism and raises interesting new possibilities for the treatment of diabetes and related disorders.
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Affiliation(s)
- Gregory J Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
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43
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Denroche HC, Levi J, Wideman RD, Sequeira RM, Huynh FK, Covey SD, Kieffer TJ. Leptin therapy reverses hyperglycemia in mice with streptozotocin-induced diabetes, independent of hepatic leptin signaling. Diabetes 2011; 60:1414-23. [PMID: 21464443 PMCID: PMC3292314 DOI: 10.2337/db10-0958] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Leptin therapy has been found to reverse hyperglycemia and prevent mortality in several rodent models of type 1 diabetes. Yet the mechanism of leptin-mediated reversal of hyperglycemia has not been fully defined. The liver is a key organ regulating glucose metabolism and is also a target of leptin action. Thus we hypothesized that exogenous leptin administered to mice with streptozotocin (STZ)-induced diabetes reverses hyperglycemia through direct action on hepatocytes. RESEARCH DESIGN AND METHODS After the induction of diabetes in mice with a high dose of STZ, recombinant mouse leptin was delivered at a supraphysiological dose for 14 days by an osmotic pump implant. We characterized the effect of leptin administration in C57Bl/6J mice with STZ-induced diabetes and then examined whether leptin therapy could reverse STZ-induced hyperglycemia in mice in which hepatic leptin signaling was specifically disrupted. RESULTS Hyperleptinemia reversed hyperglycemia and hyperketonemia in diabetic C57Bl/6J mice and dramatically improved glucose tolerance. These effects were associated with reduced plasma glucagon and growth hormone levels and dramatically enhanced insulin sensitivity, without changes in glucose uptake by skeletal muscle. Leptin therapy also ameliorated STZ-induced hyperglycemia and hyperketonemia in mice with disrupted hepatic leptin signaling to a similar extent as observed in wild-type littermates with STZ-induced diabetes. CONCLUSIONS These observations reveal that hyperleptinemia reverses the symptoms of STZ-induced diabetes in mice and that this action does not require direct leptin signaling in the liver.
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Affiliation(s)
- Heather C. Denroche
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jasna Levi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rhonda D. Wideman
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Roveena M. Sequeira
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Frank K. Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scott D. Covey
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J. Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding author: Timothy J. Kieffer,
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MacDonald PE, Rorsman P. Per-arnt-sim (PAS) domain kinase (PASK) as a regulator of glucagon secretion. Diabetologia 2011; 54:719-21. [PMID: 21327866 DOI: 10.1007/s00125-011-2072-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 01/19/2011] [Indexed: 12/21/2022]
Abstract
The physiological and pathophysiological regulation of glucagon secretion from pancreatic alpha cells remains a hotly debated topic. The mechanism(s) contributing to the glucose sensitivity of glucagon release and its impaired regulation in diabetes remain unclear. A paper in the current issue of Diabetologia by da Silva Xavier and colleagues (doi: 10.1007/s00125-010-2010-7 ) provides intriguing new insight into a metabolic sensing pathway mediated by the per-arnt-sim (PAS) domain kinase (PASK) that may contribute to both the paracrine and the intrinsic glucose regulation of alpha cells. Importantly, the authors show that PASK is decreased in islets from patients with type 2 diabetes, providing a potential mechanism for impaired suppression of glucagon by hyperglycaemia in this disease. Much work remains to be done to determine the exact role and mechanism of PASK in alpha and beta cells. Nevertheless, the present work introduces a new player in the metabolic regulation of glucagon secretion.
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Affiliation(s)
- P E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada.
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Liu J, Hunter CS, Du A, Ediger B, Walp E, Murray J, Stein R, May CL. Islet-1 regulates Arx transcription during pancreatic islet alpha-cell development. J Biol Chem 2011; 286:15352-60. [PMID: 21388963 DOI: 10.1074/jbc.m111.231670] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Aristaless related homeodomain protein (Arx) specifies the formation of the pancreatic islet α-cell during development. This cell type produces glucagon, a major counteracting hormone to insulin in regulating glucose homeostasis in adults. However, little is known about the factors that regulate Arx transcription in the pancreas. In this study, we showed that the number of Arx(+) cells was significantly reduced in the pancreata of embryos deficient for the Islet-1 (Isl-1) transcription factor, which was also supported by the reduction in Arx mRNA levels. Chromatin immunoprecipitation analysis localized Isl-1 activator binding sites within two highly conserved noncoding regulatory regions (Re) in the Arx locus, termed Re1 (+5.6 to +6.1 kb) and Re2 (+23.6 to +24 kb). Using cell line-based transfection assays, we demonstrated that a Re1- and Re2-driven reporter was selectively activated in islet α-cells, a process mediated by Isl-1 in overexpression, knockdown, and site-directed mutation experiments. Moreover, Arx mRNA levels were up-regulated in islet α-cells upon Isl-1 overexpression in vivo. Isl-1 represents the first known activator of Arx transcription in α-cells, here established to be acting through the conserved Re1 and Re2 control domains.
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Affiliation(s)
- Jingxuan Liu
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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46
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German JP, Thaler JP, Wisse BE, Oh-I S, Sarruf DA, Matsen ME, Fischer JD, Taborsky GJ, Schwartz MW, Morton GJ. Leptin activates a novel CNS mechanism for insulin-independent normalization of severe diabetic hyperglycemia. Endocrinology 2011; 152:394-404. [PMID: 21159853 PMCID: PMC3037161 DOI: 10.1210/en.2010-0890] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The brain has emerged as a target for the insulin-sensitizing effects of several hormonal and nutrient-related signals. The current studies were undertaken to investigate mechanisms whereby leptin lowers circulating blood glucose levels independently of insulin. After extending previous evidence that leptin infusion directly into the lateral cerebral ventricle ameliorates hyperglycemia in rats with streptozotocin-induced uncontrolled diabetes mellitus, we showed that the underlying mechanism is independent of changes of food intake, urinary glucose excretion, or recovery of pancreatic β-cells. Instead, leptin action in the brain potently suppresses hepatic glucose production while increasing tissue glucose uptake despite persistent, severe insulin deficiency. This leptin action is distinct from its previously reported effect to increase insulin sensitivity in the liver and offers compelling evidence that the brain has the capacity to normalize diabetic hyperglycemia in the presence of sufficient amounts of central nervous system leptin.
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Affiliation(s)
- Jonathan P German
- Department of Medicine, University of Washington at South Lake Union, 815 Mercer Street, N334, PO Box 358055, Seattle, Washington 98195, USA
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Abstract
OBJECTIVE To determine the role of glucagon action in the metabolic phenotype of untreated insulin deficiency. RESEARCH DESIGN AND METHODS We compared pertinent clinical and metabolic parameters in glucagon receptor-null (Gcgr(-/-)) mice and wild-type (Gcgr(+/+)) controls after equivalent destruction of β-cells. We used a double dose of streptozotocin to maximize β-cell destruction. RESULTS Gcgr(+/+) mice became hyperglycemic (>500 mg/dL), hyperketonemic, polyuric, and cachectic and had to be killed after 6 weeks. Despite comparable β-cell destruction in Gcgr(-/-) mice, none of the foregoing clinical or laboratory manifestations of diabetes appeared. There was marked α-cell hyperplasia and hyperglucagonemia (~1,200 pg/mL), but hepatic phosphorylated cAMP response element binding protein and phosphoenolpyruvate carboxykinase mRNA were profoundly reduced compared with Gcgr(+/+) mice with diabetes--evidence that glucagon action had been effectively blocked. Fasting glucose levels and oral and intraperitoneal glucose tolerance tests were normal. Both fasting and nonfasting free fatty acid levels and nonfasting β-hydroxy butyrate levels were lower. CONCLUSIONS We conclude that blocking glucagon action prevents the deadly metabolic and clinical derangements of type 1 diabetic mice.
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Affiliation(s)
- Young Lee
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - May-Yun Wang
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Xiu Quan Du
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Maureen J. Charron
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Roger H. Unger
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- VA North Texas Health Care System, Dallas, Texas
- Corresponding author: Roger H. Unger,
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Insulin and glucagon regulate pancreatic α-cell proliferation. PLoS One 2011; 6:e16096. [PMID: 21283589 PMCID: PMC3026810 DOI: 10.1371/journal.pone.0016096] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 12/08/2010] [Indexed: 02/07/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) results from insulin resistance and β-cell dysfunction, in the setting of hyperglucagonemia. Glucagon is a 29 amino acid peptide hormone, which is secreted from pancreatic α cells: excessively high circulating levels of glucagon lead to excessive hepatic glucose output. We investigated if α-cell numbers increase in T2DM and what factor (s) regulate α-cell turnover. Leprdb/Leprdb (db/db) mice were used as a T2DM model and αTC1 cells were used to study potential α-cell trophic factors. Here, we demonstrate that in db/db mice α-cell number and plasma glucagon levels increased as diabetes progressed. Insulin treatment (EC50 = 2 nM) of α cells significantly increased α-cell proliferation in a concentration-dependent manner compared to non-insulin-treated α cells. Insulin up-regulated α-cell proliferation through the IR/IRS2/AKT/mTOR signaling pathway, and increased insulin-mediated proliferation was prevented by pretreatment with rapamycin, a specific mTOR inhibitor. GcgR antagonism resulted in reduced rates of cell proliferation in αTC1 cells. In addition, blockade of GcgRs in db/db mice improved glucose homeostasis, lessened α-cell proliferation, and increased intra-islet insulin content in β cells in db/db mice. These studies illustrate that pancreatic α-cell proliferation increases as diabetes develops, resulting in elevated plasma glucagon levels, and both insulin and glucagon are trophic factors to α-cells. Our current findings suggest that new therapeutic strategies for the treatment of T2DM may include targeting α cells and glucagon.
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Leptin therapy improves insulin-deficient type 1 diabetes by CNS-dependent mechanisms in mice. Proc Natl Acad Sci U S A 2010; 107:17391-6. [PMID: 20855609 DOI: 10.1073/pnas.1008025107] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Leptin monotherapy reverses the deadly consequences and improves several of the metabolic imbalances caused by insulin-deficient type 1 diabetes (T1D) in rodents. However, the mechanism(s) underlying these effects is totally unknown. Here, we report that intracerebroventricular (icv) infusion of leptin reverses lethality and greatly improves hyperglycemia, hyperglucagonemia, hyperketonemia, and polyuria caused by insulin deficiency in mice. Notably, icv leptin administration leads to increased body weight while suppressing food intake, thus correcting the catabolic consequences of T1D. Also, icv leptin delivery improves expression of the metabolically relevant hypothalamic neuropeptides proopiomelanocortin, neuropeptide Y, and agouti-related peptide in T1D mice. Furthermore, this treatment normalizes phosphoenolpyruvate carboxykinase 1 contents without affecting glycogen levels in the liver. Pancreatic β-cell regeneration does not underlie these beneficial effects of leptin, because circulating insulin levels were undetectable at basal levels and following a glucose overload. Also, pancreatic preproinsulin mRNA was completely absent in these icv leptin-treated T1D mice. Furthermore, the antidiabetic effects of icv leptin administration rapidly vanished (i.e., within 48 h) after leptin treatment was interrupted. Collectively, these results unveil a key role for the brain in mediating the antidiabetic actions of leptin in the context of T1D.
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Paracrinology of islets and the paracrinopathy of diabetes. Proc Natl Acad Sci U S A 2010; 107:16009-12. [PMID: 20798346 DOI: 10.1073/pnas.1006639107] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
New results have brought to light the importance of the regulation of glucagon by β-cells in the development of diabetes. In this perspective, we examine the normal paracrinology of α- and β-cells in nondiabetic pancreatic islets. We propose a Sherringtonian model of coordinated reciprocal secretory responses of these juxtaposed cells that secrete glucagon and insulin, hormones with opposing actions on the liver. As insulin is a powerful inhibitor of glucagon, we propose that within-islet inhibition of α-cells by β-cells creates an insulin-to-glucagon ratio that maintains glycemic stability even in extremes of glucose influx or efflux. By contrast, in type 1 diabetes mellitus, α-cells lack constant action of high insulin levels from juxtaposed β-cells. Replacement with exogenous insulin does not approach paracrine levels of secreted insulin except with high doses that "overinsulinize" the peripheral insulin targets, thereby promoting glycemic volatility. Based on the stable normoglycemia of mice with type 1 diabetes during suppression of glucagon with leptin, we conclude that, in the absence of paracrine regulation of α-cells, tonic inhibition of α-cells improves the dysregulated glucose homeostasis. These results have considerable medical implications, as they suggest new approaches to normalize the extreme volatility of glycemia in diabetic patients.
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