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Ali II, D’Souza C, Tariq S, Adeghate EA. Adropin Is Expressed in Pancreatic Islet Cells and Reduces Glucagon Release in Diabetes Mellitus. Int J Mol Sci 2024; 25:9824. [PMID: 39337311 PMCID: PMC11432804 DOI: 10.3390/ijms25189824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 08/30/2024] [Accepted: 09/06/2024] [Indexed: 09/30/2024] Open
Abstract
Diabetes mellitus affects 537 million adults around the world. Adropin is expressed in different cell types. Our aim was to investigate the cellular localization in the endocrine pancreas and its effect on modulating pancreatic endocrine hormone release in streptozotocin (STZ)-induced diabetic rats. Adropin expression in the pancreas was investigated in normal and diabetic rats using immunohistochemistry and immunoelectron microscopy. Serum levels of insulin, glucagon pancreatic polypeptide (PP), and somatostatin were measured using a Luminex® χMAP (Magpix®) analyzer. Pancreatic endocrine hormone levels in INS-1 832/3 rat insulinoma cells, as well as pancreatic tissue fragments of normal and diabetic rats treated with different concentrations of adropin (10-6, 10-9, and 10-12 M), were measured using ELISA. Adropin was colocalized with cells producing either insulin, glucagon, or PP. Adropin treatment reduced the number of glucagon-secreting alpha cells and suppressed glucagon release from the pancreas. The serum levels of GLP-1 and amylin were significantly increased after treatment with adropin. Our study indicates a potential role of adropin in modulating glucagon secretion in animal models of diabetes mellitus.
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Affiliation(s)
- Ifrah I. Ali
- Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (I.I.A.); (C.D.); (S.T.)
| | - Crystal D’Souza
- Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (I.I.A.); (C.D.); (S.T.)
| | - Saeed Tariq
- Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (I.I.A.); (C.D.); (S.T.)
| | - Ernest A. Adeghate
- Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (I.I.A.); (C.D.); (S.T.)
- Zayed Foundation, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
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Visa M, Berggren PO. Sex-dependent intra-islet structural rearrangements affecting alpha-to-beta cell interactions lead to adaptive enhancements of Ca 2+ dynamics in prediabetic beta cells. Diabetologia 2024; 67:1663-1682. [PMID: 38814444 PMCID: PMC11343800 DOI: 10.1007/s00125-024-06173-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 04/09/2024] [Indexed: 05/31/2024]
Abstract
AIMS/HYPOTHESIS Prediabetic pancreatic beta cells can adapt their function to maintain normoglycaemia for a limited period of time, after which diabetes mellitus will manifest upon beta cell exhaustion. Understanding sex-specific beta cell compensatory mechanisms and their failure in prediabetes (impaired glucose tolerance) is crucial for early disease diagnosis and individualised treatment. Our aims were as follows: (1) to determine the key time points of the progression from beta cells' functional adaptations to their failure in vivo; and (2) to mechanistically explain in vivo sex-specific beta cell compensatory mechanisms and their failure in prediabetes. METHODS Islets from male and female transgenic Ins1CreERT2-GCaMP3 mice were transplanted into the anterior chamber of the eye of 10- to 12-week-old sex-matched C57BL/6J mice. Recipient mice were fed either a control diet (CD) or western diet (WD) for a maximum of 4 months. Metabolic variables were evaluated monthly. Beta cell cytoplasmic free calcium concentration ([Ca2+]i) dynamics were monitored in vivo longitudinally by image fluorescence of the GCaMP3 reporter islets. Global islet beta cell [Ca2+]i dynamics in line with single beta cell [Ca2+]i analysis were used for beta cell coordination studies. The glucagon receptor antagonist L-168,049 (4 mmol/l) was applied topically to the transplanted eyes to evaluate in vivo the effect of glucagon on beta cell [Ca2+]idynamics. Human islets from non-diabetic women and men were cultured for 24 h in either a control medium or high-fat/high-glucose medium in the presence or absence of the glucagon receptor antagonist L-168,049. [Ca2+]i dynamics of human islets were evaluated in vitro after 1 h exposure to Fura-10. RESULTS Mice fed a WD for 1 month displayed increased beta cell [Ca2+]i dynamics linked to enhanced insulin secretion as a functional compensatory mechanism in prediabetes. Recruitment of inactive beta cells in WD-fed mice explained the improved beta cell function adaptation observed in vivo; this occurred in a sex-specific manner. Mechanistically, this was attributable to an intra-islet structural rearrangement involving alpha cells. These sex-dependent cytoarchitecture reorganisations, observed in both mice and humans, induced enhanced paracrine input from adjacent alpha cells, adjusting the glucose setpoint and amplifying the insulin secretion pathway. When WD feeding was prolonged, female mice maintained the adaptive mechanism due to their intrinsically high proportion of alpha cells. In males, [Ca2+]i dynamics progressively declined subsequent to glucose stimulation while insulin secretion continue to increase, suggesting uncoordinated beta cell function as an early sign of diabetes. CONCLUSIONS/INTERPRETATION We identified increased coordination of [Ca2+]i dynamics as a beta cell functional adaptation mechanisms in prediabetes. Importantly, we uncovered the mechanisms by which sex-dependent beta cell [Ca2+]i dynamics coordination is orchestrated by an intra-islet structure reorganisation increasing the paracrine input from alpha cells on beta cell function. Moreover, we identified reduced [Ca2+]i dynamics coordination in response to glucose as an early sign of diabetes preceding beta cell secretory dysfunction, with males being more vulnerable. Alterations in coordination capacity of [Ca2+]i dynamics may thus serve as an early marker for beta cell failure in prediabetes.
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Affiliation(s)
- Montse Visa
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
- Tecnológico de Monterrey, Real San Agustín, Mexico.
- West China Hospital, Sichuan University, Chengdu, China.
- School of Biomedical Sciences, Ulster University, Coleraine, UK.
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Hu Y, Huang H, Xiang R. GCGR: novel potential therapeutic target for chronic kidney disease. SCIENCE CHINA. LIFE SCIENCES 2024; 67:1542-1544. [PMID: 38679668 DOI: 10.1007/s11427-024-2576-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 03/22/2024] [Indexed: 05/01/2024]
Affiliation(s)
- Yan Hu
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Hao Huang
- Department of Nephrology, Xiangya Hospital Central South University, Changsha, 410008, China.
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, 410013, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China.
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, 410013, China.
| | - Rong Xiang
- Department of Nephrology, Xiangya Hospital Central South University, Changsha, 410008, China.
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, 410013, China.
- Hunan Key Laboratory of Organ Fibrosis, Central South University, Changsha, 410013, China.
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Hill TG, Hill DJ. The Importance of Intra-Islet Communication in the Function and Plasticity of the Islets of Langerhans during Health and Diabetes. Int J Mol Sci 2024; 25:4070. [PMID: 38612880 PMCID: PMC11012451 DOI: 10.3390/ijms25074070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes.
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Affiliation(s)
- Thomas G. Hill
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - David J. Hill
- Lawson Health Research Institute, St. Joseph’s Health Care, London, ON N6A 4V2, Canada;
- Departments of Medicine, Physiology and Pharmacology, Western University, London, ON N6A 3K7, Canada
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Chia CW, Yeager SM, Egan JM. Endocrinology of Taste with Aging. Endocrinol Metab Clin North Am 2023; 52:295-315. [PMID: 36948781 PMCID: PMC10037529 DOI: 10.1016/j.ecl.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Taste is one of our five primary senses, and taste impairment has been shown to increase with aging. The ability to taste allows us to enjoy the food we eat and to avoid foods that are potentially spoiled or poisonous. Recent advances in our understanding of the molecular mechanisms of taste receptor cells located within taste buds help us decipher how taste works. The discoveries of "classic" endocrine hormones in taste receptor cells point toward taste buds being actual endocrine organs. A better understanding of how taste works may help in reversing taste impairment associated with aging.
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Affiliation(s)
- Chee W Chia
- Intramural Research Program, National Institute on Aging, National Institutes of Health, 3001 S. Hanover Street, 5th Floor, Room NM536, Baltimore, MD 21225, USA
| | - Shayna M Yeager
- Intramural Research Program, National Institute on Aging, National Institutes of Health, 3001 S. Hanover Street, 5th Floor, Room NM547, Baltimore, MD 21225, USA
| | - Josephine M Egan
- Intramural Research Program, National Institute on Aging, National Institutes of Health, 3001 S. Hanover Street, 5th Floor, Room NM527, Baltimore, MD 21225, USA.
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Caruso I, Marrano N, Biondi G, Genchi VA, D'Oria R, Sorice GP, Perrini S, Cignarelli A, Natalicchio A, Laviola L, Giorgino F. Glucagon in type 2 diabetes: Friend or foe? Diabetes Metab Res Rev 2023; 39:e3609. [PMID: 36637256 DOI: 10.1002/dmrr.3609] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/02/2022] [Accepted: 12/30/2022] [Indexed: 01/14/2023]
Abstract
Hyperglucagonemia is one of the 'ominous' eight factors underlying the pathogenesis of type 2 diabetes (T2D). Glucagon is a peptide hormone involved in maintaining glucose homoeostasis by increasing hepatic glucose output to counterbalance insulin action. Long neglected, the introduction of dual and triple agonists exploiting glucagon signalling pathways has rekindled the interest in this hormone beyond its classic effect on glycaemia. Glucagon can promote weight loss by regulating food intake, energy expenditure, and brown and white adipose tissue functions through mechanisms still to be fully elucidated, thus its role in T2D pathogenesis should be further investigated. Moreover, the role of glucagon in the development of T2D micro- and macro-vascular complications is elusive. Mounting evidence suggests its beneficial effect in non-alcoholic fatty liver disease, while few studies postulated its favourable role in peripheral neuropathy and retinopathy. Contrarily, glucagon receptor agonism might induce renal changes resembling diabetic nephropathy, and data concerning glucagon actions on the cardiovascular system are conflicting. This review aims to summarise the available findings on the role of glucagon in the pathogenesis of T2D and its complications. Further experimental and clinical data are warranted to better understand the implications of glucagon signalling modulation with new antidiabetic drugs.
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Affiliation(s)
- Irene Caruso
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Nicola Marrano
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Giuseppina Biondi
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Valentina Annamaria Genchi
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Rossella D'Oria
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Gian Pio Sorice
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Sebastio Perrini
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Angelo Cignarelli
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Annalisa Natalicchio
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Luigi Laviola
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
| | - Francesco Giorgino
- Department of Precision and Regenerative Medicine and Ionian Area, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Bari, Italy
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Lin Y, Pan J, Liu Y, Yang H, Wu G, Pan Y. Acanthopanax trifoliatus (L.) Merr polysaccharides ameliorates hyperglycemia by regulating hepatic glycogen metabolism in type 2 diabetic mice. Front Nutr 2023; 10:1111287. [PMID: 36845056 PMCID: PMC9948035 DOI: 10.3389/fnut.2023.1111287] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 01/12/2023] [Indexed: 02/11/2023] Open
Abstract
INTRODUCTION Drug monotherapy was inadequate in controlling blood glucose levels and other comorbidities. An agent that selectively tunes multiple targets was regarded as a new therapeutic strategy for type 2 diabetes. Acanthopanax trifoliatus (L.) Merr polysaccharide (ATMP) is a bio-macromolecule isolated from Acanthopanax trifoliatus (L.) Merr and has therapeutic potential for diabetes management due to its anti-hyperglycemia activity. METHODS Type 2 diabetes mellitus was induced in mice using streptozotocin, and 40 and 80 mg/kg ATMP was administered daily via the intragastric route for 8 weeks. Food intake, water intake, and body weight were recorded. The fasting blood glucose (FBG), fasting insulin (FINS) and an oral glucose tolerance test (OGTT) were performed. Histological changes in the liver and pancreas were analyzed by H&E staining. The mRNA and the protein levels of key factors involved in glycogen synthesis, glycogenolysis, and gluconeogenesis were measured by quantitative real time PCR and Western blotting. RESULTS In this study, we found that ATMP could effectively improve glucose tolerance and alleviate insulin resistance by promoting insulin secretion and inhibiting glucagon secretion. In addition, ATMP decreases glycogen synthesis by inhibiting PI3K/Akt/GSK3β signaling, reduces glycogenolysis via suppressing cAMP/PKA signaling, and suppresses liver gluconeogenesis by activating AMPK signaling. CONCLUSION Together, ATMP has the potential to be developed as a new multitargets therapeutics for type 2 diabetes.
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Affiliation(s)
- Yuzi Lin
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
| | - Jinghua Pan
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yue Liu
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
| | - Huiwen Yang
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
| | - Guoyu Wu
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
- Key Specialty of Clinical Pharmacy, The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China
- *Correspondence: Guoyu Wu, ✉
| | - Yufang Pan
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Advanced Drug Delivery and Guangdong Provincial Engineering Center of Topical Precise Drug Delivery System, Guangdong Pharmaceutical University, Guangzhou, China
- Yufang Pan, ✉
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Bosma KJ, Andrei SR, Katz LS, Smith AA, Dunn JC, Ricciardi VF, Ramirez MA, Baumel-Alterzon S, Pace WA, Carroll DT, Overway EM, Wolf EM, Kimple ME, Sheng Q, Scott DK, Breyer RM, Gannon M. Pharmacological blockade of the EP3 prostaglandin E 2 receptor in the setting of type 2 diabetes enhances β-cell proliferation and identity and relieves oxidative damage. Mol Metab 2021; 54:101347. [PMID: 34626853 PMCID: PMC8529552 DOI: 10.1016/j.molmet.2021.101347] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/02/2021] [Accepted: 09/23/2021] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVE Type 2 diabetes is characterized by hyperglycemia and inflammation. Prostaglandin E2, which signals through four G protein-coupled receptors (EP1-4), is a mediator of inflammation and is upregulated in diabetes. We have shown previously that EP3 receptor blockade promotes β-cell proliferation and survival in isolated mouse and human islets ex vivo. Here, we analyzed whether systemic EP3 blockade could enhance β-cell mass and identity in the setting of type 2 diabetes using mice with a spontaneous mutation in the leptin receptor (Leprdb). METHODS Four- or six-week-old, db/+, and db/db male mice were treated with an EP3 antagonist daily for two weeks. Pancreata were analyzed for α-cell and β-cell proliferation and β-cell mass. Islets were isolated for transcriptomic analysis. Selected gene expression changes were validated by immunolabeling of the pancreatic tissue sections. RESULTS EP3 blockade increased β-cell mass in db/db mice through enhanced β-cell proliferation. Importantly, there were no effects on α-cell proliferation. EP3 blockade reversed the changes in islet gene expression associated with the db/db phenotype and restored the islet architecture. Expression of the GLP-1 receptor was slightly increased by EP3 antagonist treatment in db/db mice. In addition, the transcription factor nuclear factor E2-related factor 2 (Nrf2) and downstream targets were increased in islets from db/db mice in response to treatment with an EP3 antagonist. The markers of oxidative stress were decreased. CONCLUSIONS The current study suggests that EP3 blockade promotes β-cell mass expansion in db/db mice. The beneficial effects of EP3 blockade may be mediated through Nrf2, which has recently emerged as a key mediator in the protection against cellular oxidative damage.
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Affiliation(s)
- Karin J Bosma
- Dept. of Veterans Affairs Tennessee Valley Authority, Nashville, TN, USA; Dept. of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Spencer R Andrei
- Dept. of Veterans Affairs Tennessee Valley Authority, Nashville, TN, USA; Dept. of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Liora S Katz
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ashley A Smith
- Dept. of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Jennifer C Dunn
- Dept. of Veterans Affairs Tennessee Valley Authority, Nashville, TN, USA; Dept. of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Marisol A Ramirez
- Center for Quantitative Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Dept. of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sharon Baumel-Alterzon
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - William A Pace
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Darian T Carroll
- Dept. of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Emily M Overway
- Dept. of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Elysa M Wolf
- Program in Cancer Biology, Vanderbilt University, Nashville, TN, USA
| | - Michelle E Kimple
- Dept. of Medicine, University of Wisconsin, Madison, WI, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Quanhu Sheng
- Center for Quantitative Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Dept. of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Donald K Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Richard M Breyer
- Dept. of Veterans Affairs Tennessee Valley Authority, Nashville, TN, USA; Dept. of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Maureen Gannon
- Dept. of Veterans Affairs Tennessee Valley Authority, Nashville, TN, USA; Dept. of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Dept. of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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Martínez MS, Manzano A, Olivar LC, Nava M, Salazar J, D’Marco L, Ortiz R, Chacín M, Guerrero-Wyss M, Cabrera de Bravo M, Cano C, Bermúdez V, Angarita L. The Role of the α Cell in the Pathogenesis of Diabetes: A World beyond the Mirror. Int J Mol Sci 2021; 22:9504. [PMID: 34502413 PMCID: PMC8431704 DOI: 10.3390/ijms22179504] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/11/2022] Open
Abstract
Type 2 Diabetes Mellitus (T2DM) is one of the most prevalent chronic metabolic disorders, and insulin has been placed at the epicentre of its pathophysiological basis. However, the involvement of impaired alpha (α) cell function has been recognized as playing an essential role in several diseases, since hyperglucagonemia has been evidenced in both Type 1 and T2DM. This phenomenon has been attributed to intra-islet defects, like modifications in pancreatic α cell mass or dysfunction in glucagon's secretion. Emerging evidence has shown that chronic hyperglycaemia provokes changes in the Langerhans' islets cytoarchitecture, including α cell hyperplasia, pancreatic beta (β) cell dedifferentiation into glucagon-positive producing cells, and loss of paracrine and endocrine regulation due to β cell mass loss. Other abnormalities like α cell insulin resistance, sensor machinery dysfunction, or paradoxical ATP-sensitive potassium channels (KATP) opening have also been linked to glucagon hypersecretion. Recent clinical trials in phases 1 or 2 have shown new molecules with glucagon-antagonist properties with considerable effectiveness and acceptable safety profiles. Glucagon-like peptide-1 (GLP-1) agonists and Dipeptidyl Peptidase-4 inhibitors (DPP-4 inhibitors) have been shown to decrease glucagon secretion in T2DM, and their possible therapeutic role in T1DM means they are attractive as an insulin-adjuvant therapy.
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Affiliation(s)
- María Sofía Martínez
- MedStar Health Internal Medicine, Georgetown University Affiliated, Baltimore, MD 21218-2829, USA;
| | - Alexander Manzano
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Luis Carlos Olivar
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Manuel Nava
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Juan Salazar
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Luis D’Marco
- Department of Nephrology, Hospital Clinico Universitario de Valencia, INCLIVA, University of Valencia, 46010 Valencia, Spain;
| | - Rina Ortiz
- Facultad de Medicina, Universidad Católica de Cuenca, Ciudad de Cuenca, Azuay 010105, Ecuador;
| | - Maricarmen Chacín
- Facultad de Ciencias de la Salud, Universidad Simón Bolívar, Barranquilla 080022, Colombia; (M.C.); (V.B.)
| | - Marion Guerrero-Wyss
- Escuela de Nutrición y Dietética, Facultad de Ciencias Para el Cuidado de la Salud, Universidad San Sebastián, Valdivia 5090000, Chile;
| | | | - Clímaco Cano
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Valmore Bermúdez
- Facultad de Ciencias de la Salud, Universidad Simón Bolívar, Barranquilla 080022, Colombia; (M.C.); (V.B.)
| | - Lisse Angarita
- Escuela de Nutrición y Dietética, Facultad de Medicina, Universidad Andres Bello, Sede Concepción 4260000, Chile
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Abbas E, Ahmed Siddiqui I, Khan MS, Perveen K, Butt A, Fawwad A. Fasting Glucagon Level in Type 2 Diabetes and Impaired Glucose Tolerance and Its Association With Diabetes-Associated Clinical Parameters: A Study From Karachi, Pakistan. Cureus 2021; 13:e13430. [PMID: 33758717 PMCID: PMC7978393 DOI: 10.7759/cureus.13430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Aim and objective The study aims to analyze fasting glucagon in patients with type 2 diabetes and impaired glucose tolerance and correlate it with anthropometric and biochemical parameters in a large proportion of Pakistani people with diabetes. Methodology The participants of the study were categorized into three groups based on oral glucose tolerance test, as per American Diabetes Association guidelines. Group A consisted of normal glucose tolerance subjects (n=30), Group B consisted of subjects with impaired glucose tolerance (n=30), and Group C had full-blown subjects with type 2 diabetes (n=30). Biochemical parameters, such as fasting glucagon, fasting plasma and 2-hour glucose, glycated hemoglobin, and lipid profile, and anthropometric parameters, such as body mass index (BMI), waist and hip circumference, waist-to-hip ratio, and systolic and diastolic blood pressure, were measured. Results The mean values of fasting glucagon level in Group A, Group B, and Group C were 39.24±4.5, 44.5±8.25, and 49.02±9.15 pg/ml, respectively. Statistically significant difference was not found in fasting glucagon level among these groups (p-value 0.614). Fasting glucagon was positively and independently correlated with 2-hour plasma glucose, systolic blood pressure, diastolic blood pressure, BMI, hip and waist circumference, and hip-to-waist ratio in Group C. In Group B, fasting glucagon was positively correlated with 2-hour plasma glucose, BMI, and hip circumference, while it was not correlated with fasting plasma glucose in both groups. In Group A, fasting glucagon found positively correlated with systolic blood pressure and hip circumference. Conclusion Our observation suggests that fasting plasma glucose is not concomitant with glucagon levels; however, glucagon suppression, after glucose intake, was dysregulated in type 2 diabetes and impaired glucose tolerance. Moreover, glucagon is associated with central obesity in type 2 diabetic patients. .
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Affiliation(s)
- Eraj Abbas
- Biochemistry, Baqai Medical University, Karachi, PAK
| | | | | | | | - Anum Butt
- Research, Baqai Institute of Diabetology and Endocrinology, Baqai Medical University, Karachi, PAK
| | - Asher Fawwad
- Research, Baqai Institute of Diabetology and Endocrinology, Baqai Medical University, Karachi, PAK
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11
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Bozadjieva Kramer N, Lubaczeuski C, Blandino-Rosano M, Barker G, Gittes GK, Caicedo A, Bernal-Mizrachi E. Glucagon Resistance and Decreased Susceptibility to Diabetes in a Model of Chronic Hyperglucagonemia. Diabetes 2021; 70:477-491. [PMID: 33239450 PMCID: PMC7881862 DOI: 10.2337/db20-0440] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 11/18/2020] [Indexed: 02/07/2023]
Abstract
Elevation of glucagon levels and increase in α-cell mass are associated with states of hyperglycemia in diabetes. Our previous studies have highlighted the role of nutrient signaling via mTOR complex 1 (mTORC1) regulation that controls glucagon secretion and α-cell mass. In the current studies we investigated the effects of activation of nutrient signaling by conditional deletion of the mTORC1 inhibitor, TSC2, in α-cells (αTSC2KO). We showed that activation of mTORC1 signaling is sufficient to induce chronic hyperglucagonemia as a result of α-cell proliferation, cell size, and mass expansion. Hyperglucagonemia in αTSC2KO was associated with an increase in glucagon content and enhanced glucagon secretion. This model allowed us to identify the effects of chronic hyperglucagonemia on glucose homeostasis by inducing insulin secretion and resistance to glucagon in the liver. Liver glucagon resistance in αTSC2KO mice was characterized by reduced expression of the glucagon receptor (GCGR), PEPCK, and genes involved in amino acid metabolism and urea production. Glucagon resistance in αTSC2KO mice was associated with improved glucose levels in streptozotocin-induced β-cell destruction and high-fat diet-induced glucose intolerance. These studies demonstrate that chronic hyperglucagonemia can improve glucose homeostasis by inducing glucagon resistance in the liver.
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Affiliation(s)
- Nadejda Bozadjieva Kramer
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI
- Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
| | - Camila Lubaczeuski
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Manuel Blandino-Rosano
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Grant Barker
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - George K Gittes
- UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburg, PA
| | - Alejandro Caicedo
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
- Veterans Affairs Medical Center, Miami, FL
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12
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Li YZ, Di Cristofano A, Woo M. Metabolic Role of PTEN in Insulin Signaling and Resistance. Cold Spring Harb Perspect Med 2020; 10:a036137. [PMID: 31964643 PMCID: PMC7397839 DOI: 10.1101/cshperspect.a036137] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Phosphatase and tensin homolog (PTEN) is most prominently known for its function in tumorigenesis. However, a metabolic role of PTEN is emerging as a result of its altered expression in type 2 diabetes (T2D), which results in impaired insulin signaling and promotion of insulin resistance during the pathogenesis of T2D. PTEN functions in regulating insulin signaling across different organs have been identified. Through the use of a variety of models, such as tissue-specific knockout (KO) mice and in vitro cell cultures, PTEN's role in regulating insulin action has been elucidated across many cell types. Herein, we will review the recent advancements in the understanding of PTEN's metabolic functions in each of the tissues and cell types that contribute to regulating systemic insulin sensitivity and discuss how PTEN may represent a promising therapeutic strategy for treatment or prevention of T2D.
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Affiliation(s)
- Yu Zhe Li
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5G 2C4, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Antonio Di Cristofano
- Department of Developmental and Molecular Biology and Medicine (Oncology), Albert Einstein College of Medicine and Albert Einstein Cancer Center, Bronx, New York 10461, USA
| | - Minna Woo
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5G 2C4, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario M5G 2M9, Canada
- Department of Immunology, University of Toronto, Toronto, Ontario M5G 2M9, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, University Health Network/Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 2C4, Canada
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13
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Mechanisms of the Regulation and Dysregulation of Glucagon Secretion. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:3089139. [PMID: 32774668 PMCID: PMC7396046 DOI: 10.1155/2020/3089139] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 07/11/2020] [Indexed: 02/06/2023]
Abstract
Glucagon, a hormone secreted by pancreatic alpha cells, contributes to the maintenance of normal blood glucose concentration by inducing hepatic glucose production in response to declining blood glucose. However, glucagon hypersecretion contributes to the pathogenesis of type 2 diabetes. Moreover, diabetes is associated with relative glucagon undersecretion at low blood glucose and oversecretion at normal and high blood glucose. The mechanisms of such alpha cell dysfunctions are not well understood. This article reviews the genesis of alpha cell dysfunctions during the pathogenesis of type 2 diabetes and after the onset of type 1 and type 2 diabetes. It unravels a signaling pathway that contributes to glucose- or hydrogen peroxide-induced glucagon secretion, whose overstimulation contributes to glucagon dysregulation, partly through oxidative stress and reduced ATP synthesis. The signaling pathway involves phosphatidylinositol-3-kinase, protein kinase B, protein kinase C delta, non-receptor tyrosine kinase Src, and phospholipase C gamma-1. This knowledge will be useful in the design of new antidiabetic agents or regimens.
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14
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Korem Kohanim Y, Tendler A, Mayo A, Friedman N, Alon U. Endocrine Autoimmune Disease as a Fragility of Immune Surveillance against Hypersecreting Mutants. Immunity 2020; 52:872-884.e5. [PMID: 32433950 PMCID: PMC7237888 DOI: 10.1016/j.immuni.2020.04.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/14/2020] [Accepted: 04/27/2020] [Indexed: 12/20/2022]
Abstract
Some endocrine organs are frequent targets of autoimmune attack. Here, we addressed the origin of autoimmune disease from the viewpoint of feedback control. Endocrine tissues maintain mass through feedback loops that balance cell proliferation and removal according to hormone-driven regulatory signals. We hypothesized the existence of a dedicated mechanism that detects and removes mutant cells that missense the signal and therefore hyperproliferate and hypersecrete with potential to disrupt organismal homeostasis. In this mechanism, hypersecreting cells are preferentially eliminated by autoreactive T cells at the cost of a fragility to autoimmune disease. The "autoimmune surveillance of hypersecreting mutants" (ASHM) hypothesis predicts the presence of autoreactive T cells in healthy individuals and the nature of self-antigens as peptides from hormone secretion pathway. It explains why some tissues get prevalent autoimmune disease, whereas others do not and instead show prevalent mutant-expansion disease (e.g., hyperparathyroidism). The ASHM hypothesis is testable, and we discuss experimental follow-up.
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Affiliation(s)
- Yael Korem Kohanim
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avichai Tendler
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avi Mayo
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Nir Friedman
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Uri Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
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15
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Wang X, Yang Z, Xu X, Jiang H, Cai C, Yu G. Odd-numbered agaro-oligosaccharides alleviate type 2 diabetes mellitus and related colonic microbiota dysbiosis in mice. Carbohydr Polym 2020; 240:116261. [PMID: 32475553 DOI: 10.1016/j.carbpol.2020.116261] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/31/2020] [Accepted: 04/04/2020] [Indexed: 02/08/2023]
Abstract
Agaro- and neoagaro-oligosaccharides with even-numbered sugar units possess a variety of biological activities. However, the effects of the odd-numbered oligosaccharides from Gracilaria agarose (OGAOs) on type 2 diabetes mellitus (T2DM) have not been reported. In this study, we aimed to evaluate the effects of OGAOs on anti-T2DM from different aspects. We found that OGAOs treatment could alleviate oxidative stress, inflammation, and the related hyperglycemia, insulin resistance, lipid accumulation, and obesity in high-fat diet (HFD) induced T2DM. Investigation of the underlying mechanism showed that colitis and colonic microbiota dysbiosis in T2DM mice were ameliorated after OGAOs treatment. First, OGAOs increased the expression of ZO-1, occludin, and AMPK, and suppressed the TLR4/MAPK/NF-κB pathway in colon indicating that OGAOs enhance intestinal integrity and conduct the anti-apoptosis effects to prevent the invasion of toxins and harmful microorganisms. Moreover, the relative abundance of Akkermansia was significantly upregulated in the gut microbiome of T2DM mice associated with a dramatic decrease of the relative abundance of Helicobacter, which are both beneficial for alleviating colitis and T2DM. In addition, Spearman's correlation analysis indicated that changes in the colonic microbiota could regulate oxidative stress, inflammation, and hyperlipidemia. In summary, the underlying mechanism of OGAOs on alleviating colitis and colonic microbiota dysbiosis in T2DM has been intensively studied, illustrating that OGAOs could be further developed as a potential pharmaceutical agent for T2DM.
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Affiliation(s)
- Xueliang Wang
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
| | - Zimei Yang
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
| | - Xu Xu
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China
| | - Hao Jiang
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China.
| | - Chao Cai
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China.
| | - Guangli Yu
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China.
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16
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Hartig SM, Cox AR. Paracrine signaling in islet function and survival. J Mol Med (Berl) 2020; 98:451-467. [PMID: 32067063 DOI: 10.1007/s00109-020-01887-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/05/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a dense cellular network comprised of several cell types with endocrine function vital in the control of glucose homeostasis, metabolism, and feeding behavior. Within the islet, endocrine hormones also form an intricate paracrine network with supportive cells (endothelial, neuronal, immune) and secondary signaling molecules regulating cellular function and survival. Modulation of these signals has potential consequences for diabetes development, progression, and therapeutic intervention. Beta cell loss, reduced endogenous insulin secretion, and dysregulated glucagon secretion are hallmark features of both type 1 and 2 diabetes that not only impact systemic regulation of glucose, but also contribute to the function and survival of cells within the islet. Advancing research and technology have revealed new islet biology (cellular identity and transcriptomes) and identified previously unrecognized paracrine signals and mechanisms (somatostatin and ghrelin paracrine actions), while shifting prior views of intraislet communication. This review will summarize the paracrine signals regulating islet endocrine function and survival, the disruption and dysfunction that occur in diabetes, and potential therapeutic targets to preserve beta cell mass and function.
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Affiliation(s)
- Sean M Hartig
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Aaron R Cox
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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17
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Wendt A, Eliasson L. Pancreatic α-cells - The unsung heroes in islet function. Semin Cell Dev Biol 2020; 103:41-50. [PMID: 31983511 DOI: 10.1016/j.semcdb.2020.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 01/15/2023]
Abstract
The pancreatic islets of Langerhans consist of several hormone-secreting cell types important for blood glucose control. The insulin secreting β-cells are the best studied of these cell types, but less is known about the glucagon secreting α-cells. The α-cells secrete glucagon as a response to low blood glucose. The major function of glucagon is to release glucose from the glycogen stores in the liver. In both type 1 and type 2 diabetes, glucagon secretion is dysregulated further exaggerating the hyperglycaemia, and in type 1 diabetes α-cells fail to counter regulate hypoglycaemia. Although glucagon has been recognized for almost 100 years, the understanding of how glucagon secretion is regulated and how glucagon act within the islet is far from complete. However, α-cell research has taken off lately which is promising for future knowledge. In this review we aim to highlight α-cell regulation and glucagon secretion with a special focus on recent discoveries from human islets. We will present some novel aspects of glucagon function and effects of selected glucose lowering agents on glucagon secretion.
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Affiliation(s)
- Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden.
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18
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Quesada-Candela C, Tudurí E, Marroquí L, Alonso-Magdalena P, Quesada I, Nadal Á. Morphological and functional adaptations of pancreatic alpha-cells during late pregnancy in the mouse. Metabolism 2020; 102:153963. [PMID: 31593706 DOI: 10.1016/j.metabol.2019.153963] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/01/2019] [Accepted: 08/26/2019] [Indexed: 01/18/2023]
Abstract
BACKGROUND Pregnancy represents a major metabolic challenge for the mother, and involves a compensatory response of the pancreatic beta-cell to maintain normoglycemia. However, although pancreatic alpha-cells play a key role in glucose homeostasis and seem to be involved in gestational diabetes, there is no information about their potential adaptations or changes during pregnancy. MATERIAL AND METHODS Non-pregnant (controls) and pregnant C57BL/6 mice at gestational day 18.5 (G18.5) and their isolated pancreatic islets were used for in vivo and ex vivo studies, respectively. The effect of pregnancy hormones was tested in glucagon-secreting α-TC1.9 cells. Immunohistochemical analysis was performed in pancreatic slices. Glucagon gene expression was monitored by RT-qPCR. Glucagon secretion and plasma hormones were measured by ELISA. RESULTS Pregnant mice on G18.5 exhibited alpha-cell hypertrophy as well as augmented alpha-cell area and mass. This alpha-cell mass expansion was mainly due to increased proliferation. No changes in alpha-cell apoptosis, ductal neogenesis, or alpha-to-beta transdifferentiation were found compared with controls. Pregnant mice on G18.5 exhibited hypoglucagonemia. Additionally, in vitro glucagon secretion at low glucose levels was decreased in isolated islets from pregnant animals. Glucagon content was also reduced. Experiments in α-TC1.9 cells indicated that, unlike estradiol and progesterone, placental lactogens and prolactin stimulated alpha-cell proliferation. Placental lactogens, prolactin and estradiol also inhibited glucagon release from α-TC1.9 cells at low glucose levels. CONCLUSIONS The pancreatic alpha-cell in mice undergoes several morphofunctional changes during late pregnancy, which may contribute to proper glucose homeostasis. Gestational hormones are likely involved in these processes.
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Affiliation(s)
- Cristina Quesada-Candela
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Eva Tudurí
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Laura Marroquí
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Paloma Alonso-Magdalena
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Ivan Quesada
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain.
| | - Ángel Nadal
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain.
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19
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Takai S, Watanabe Y, Sanematsu K, Yoshida R, Margolskee RF, Jiang P, Atsuta I, Koyano K, Ninomiya Y, Shigemura N. Effects of insulin signaling on mouse taste cell proliferation. PLoS One 2019; 14:e0225190. [PMID: 31714935 PMCID: PMC6850543 DOI: 10.1371/journal.pone.0225190] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 10/30/2019] [Indexed: 12/26/2022] Open
Abstract
Expression of insulin and its receptor (IR) in rodent taste cells has been proposed, but exactly which types of taste cells express IR and the function of insulin signaling in taste organ have yet to be determined. In this study, we analyzed expression of IR mRNA and protein in mouse taste bud cells in vivo and explored its function ex vivo in organoids, using RT-PCR, immunohistochemistry, and quantitative PCR. In mouse taste tissue, IR was expressed broadly in taste buds, including in type II and III taste cells. With using 3-D taste bud organoids, we found insulin in the culture medium significantly decreased the number of taste cell and mRNA expression levels of many taste cell genes, including nucleoside triphosphate diphosphohydrolase-2 (NTPDase2), Tas1R3 (T1R3), gustducin, carbonic anhydrase 4 (CA4), glucose transporter-8 (GLUT8), and sodium-glucose cotransporter-1 (SGLT1) in a concentration-dependent manner. Rapamycin, an inhibitor of mechanistic target of rapamycin (mTOR) signaling, diminished insulin's effects and increase taste cell generation. Altogether, circulating insulin might be an important regulator of taste cell growth and/or proliferation via activation of the mTOR pathway.
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Affiliation(s)
- Shingo Takai
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
- Monell Chemical Senses Center, Philadelphia, PA, United States of America
- * E-mail: (ST); (NS)
| | - Yu Watanabe
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
- Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Keisuke Sanematsu
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Ryusuke Yoshida
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | | | - Peihua Jiang
- Monell Chemical Senses Center, Philadelphia, PA, United States of America
| | - Ikiru Atsuta
- Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Kiyoshi Koyano
- Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yuzo Ninomiya
- Monell Chemical Senses Center, Philadelphia, PA, United States of America
- Division of Sensory Physiology, Research and Development Center for Five-Sense Devices Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
| | - Noriatsu Shigemura
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
- Division of Sensory Physiology, Research and Development Center for Five-Sense Devices Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
- * E-mail: (ST); (NS)
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20
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Lee M, Kim M, Park JS, Lee S, You J, Ahn CW, Kim KR, Kang S. Higher glucagon-to-insulin ratio is associated with elevated glycated hemoglobin levels in type 2 diabetes patients. Korean J Intern Med 2019; 34:1068-1077. [PMID: 28882024 PMCID: PMC6718759 DOI: 10.3904/kjim.2016.233] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 06/26/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND/AIMS The importance of α-cell dysfunction in the pathogenesis of type 2 diabetes has re-emerged recently. However, data on whether relative glucagon excess is present in clinical settings are scarce. We aimed to investigate associations between glucagon-to-insulin ratio and various metabolic parameters. METHODS A total of 451 patients with type 2 diabetes naïve to insulin treatment were recruited. Using glucagon-to-insulin ratio, we divided subjects into quartiles according to both fasting and postprandial glucagon-to-insulin ratios. RESULTS The mean age of the subjects was 58 years, with a mean body mass index of 25 kg/m2 . The patients in the highest quartile of glucagon-to-insulin ratio had higher glycated hemoglobin (HbA1c) levels. HbA1c levels were positively correlated with both fasting and postprandial glucagon-to-insulin ratios. Subjects in the highest quartile of postprandial glucagon-to-insulin ratio were more likely to exhibit uncontrolled hyperglycemia, even after adjusting for confounding factors (odds ratio, 2.730; 95% confidence interval, 1.236 to 6.028; p for trend < 0.01). CONCLUSION Hyperglucagonemia relative to insulin could contribute to uncontrolled hyperglycemia in type 2 diabetes patients.
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Affiliation(s)
- Minyoung Lee
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Minkyung Kim
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jong Suk Park
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Severance Institute for Vascular and Metabolic Research, Yonsei University College of Medicine, Seoul, Korea
| | - Sangbae Lee
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jihong You
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Chul Woo Ahn
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Severance Institute for Vascular and Metabolic Research, Yonsei University College of Medicine, Seoul, Korea
| | - Kyung Rae Kim
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Shinae Kang
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Severance Institute for Vascular and Metabolic Research, Yonsei University College of Medicine, Seoul, Korea
- Correspondence to Shinae Kang, M.D. Division of Endocrinology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro, Gangnam-gu, Seoul 06273, Korea Tel: +82-2-2019-3335 Fax: +82-2-3463-3882 E-mail:
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21
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Cell Autonomous Dysfunction and Insulin Resistance in Pancreatic α Cells. Int J Mol Sci 2019; 20:ijms20153699. [PMID: 31357734 PMCID: PMC6695724 DOI: 10.3390/ijms20153699] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 12/23/2022] Open
Abstract
To date, type 2 diabetes is considered to be a "bi-hormonal disorder" rather than an "insulin-centric disorder," suggesting that glucagon is as important as insulin. Although glucagon increases hepatic glucose production and blood glucose levels, paradoxical glucagon hypersecretion is observed in diabetes. Recently, insulin resistance in pancreatic α cells has been proposed to be associated with glucagon dysregulation. Moreover, cell autonomous dysfunction of α cells is involved in the etiology of diabetes. In this review, we summarize the current knowledge about the physiological and pathological roles of glucagon.
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22
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Relationships between Body Composition and Plasma Levels of Pancreatic, Gut, and Adipose Tissue Hormones in db/db Mice, a Model of Type 2 Diabetes Mellitus. Bull Exp Biol Med 2019; 167:325-328. [PMID: 31346871 DOI: 10.1007/s10517-019-04519-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Indexed: 12/25/2022]
Abstract
We studied the relationships between body composition parameters and plasma levels of pancreatic, gut, and adipose tissue hormones regulating energy balance and glucose metabolism in diabetic db/db mice (BKS.Cg-Dock7m+/+Leprdb/J). The body composition parameters in mice aged 8, 12, and 16 weeks were assessed by magnetic resonance imaging. The concentrations of insulin, glucagon, ghrelin, glucagon-like peptide-1, glucose-dependent immunotropic peptide, leptin, resistin, and plasminogen activator-1 were measured by multiplex analysis at the age of 8 and 16 weeks. In comparison with non-diabetic control (db/+), db/db mice demonstrated high fat mass and reduced lean body mass and water content. In 8- and 16-week-old db/db mice, the levels of leptin (p<0.001), insulin (p<0.01), and glucagon-like peptide-1 (p<0.05) were elevated and the concentration of ghrelin (p<0.05) was reduced. The body weight and fat mass positively correlated with the levels of leptin, insulin, plasminogen activator-1, and glucagon-like peptide-1 and negatively correlated with ghrelin concentration. The results provide further details for characteristics of db/db mice, a widely used model of obesity and type 2 diabetes mellitus.
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23
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Altay M. Which factors determine exocrine pancreatic dysfunction in diabetes mellitus? World J Gastroenterol 2019; 25:2699-2705. [PMID: 31235993 PMCID: PMC6580354 DOI: 10.3748/wjg.v25.i22.2699] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/04/2019] [Accepted: 04/20/2019] [Indexed: 02/06/2023] Open
Abstract
The exocrine structure is significantly affected by diabetes because of endocrine structure-function disorder within the pancreas. Exocrine pancreatic dysfunction (EPD) is the general name of the malabsorption process resulting from inadequate production, release, decreased activation, and/or insufficient degradation of enzymes required for digestion from pancreatic acinar cells. It is important to diagnose patients early and correctly, since there may be both macro- and micro-nutrient deficiency in EPD. In this paper, EPD, the diabetes-EPD relationship, and the predictive, effective factors affecting the emergence of EPD are briefly explained and summarized with contemporary literature and our experienced based on clinical, lab, and radiological findings.
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Affiliation(s)
- Mustafa Altay
- Department of Endocrinology and Metabolism, University of Health Sciences, Keçiören Health Administration and Research Center, Ankara 06100, Turkey
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24
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Mezza T, Cinti F, Cefalo CMA, Pontecorvi A, Kulkarni RN, Giaccari A. β-Cell Fate in Human Insulin Resistance and Type 2 Diabetes: A Perspective on Islet Plasticity. Diabetes 2019; 68:1121-1129. [PMID: 31109941 PMCID: PMC6905483 DOI: 10.2337/db18-0856] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 03/17/2019] [Indexed: 12/23/2022]
Abstract
Although it is well established that type 2 diabetes (T2D) is generally due to the progressive loss of β-cell insulin secretion against a background of insulin resistance, the actual correlation of reduced β-cell mass to its defective function continues to be debated. There is evidence that a compensatory increase in β-cell mass, and the consequent insulin secretion, can effectively cope with states of insulin resistance, until hyperglycemia supervenes. Recent data strongly indicate that the mechanisms by which islets are able to compensate in response to insulin resistance in peripheral tissues is secondary to hyperplasia, as well as the activation of multiple cellular machineries with diverse functions. Importantly, islet cells exhibit plasticity in altering their endocrine commitment; for example, by switching from secretion of glucagon to secretion of insulin and back (transdifferentiation) or from an active secretory state to a nonsecretory quiescent state (dedifferentiation) and back. Lineage tracing (a method used to track each cell though its differentiation process) has demonstrated these potentials in murine models. A limitation to drawing conclusions from human islet research is that most studies are derived from human autopsy and/or organ donor samples, which lack in vivo functional and metabolic profiling. In this review, we specifically focus on evidence of islet plasticity in humans-from the normal state, progressing to insulin resistance to overt T2D-to explain the seemingly contradictory results from different cross-sectional studies in the literature. We hope the discussion on this intriguing scenario will provide a forum for the scientific community to better understand the disease and in the long term pave the way for personalized therapies.
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Affiliation(s)
- Teresa Mezza
- U.O.C. Endocrinologia e Diabetologia, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italia
- Istituto di Patologia Speciale Medica e Semeiotica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Francesca Cinti
- U.O.C. Endocrinologia e Diabetologia, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italia
- Istituto di Patologia Speciale Medica e Semeiotica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Chiara Maria Assunta Cefalo
- U.O.C. Endocrinologia e Diabetologia, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italia
- Istituto di Patologia Speciale Medica e Semeiotica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Alfredo Pontecorvi
- U.O.C. Endocrinologia e Diabetologia, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italia
- Istituto di Patologia Speciale Medica e Semeiotica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Rohit N Kulkarni
- Islet Cell & Regenerative Biology, Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Andrea Giaccari
- U.O.C. Endocrinologia e Diabetologia, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italia
- Istituto di Patologia Speciale Medica e Semeiotica Clinica, Università Cattolica del Sacro Cuore, Roma, Italia
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25
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Offspring of Mice Exposed to a Low-Protein Diet in Utero Demonstrate Changes in mTOR Signaling in Pancreatic Islets of Langerhans, Associated with Altered Glucagon and Insulin Expression and a Lower β-Cell Mass. Nutrients 2019; 11:nu11030605. [PMID: 30871106 PMCID: PMC6471519 DOI: 10.3390/nu11030605] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 02/07/2023] Open
Abstract
Low birth weight is a risk factor for gestational and type 2 diabetes (T2D). Since mammalian target of rapamycin (mTOR) controls pancreatic β-cell mass and hormone release, we hypothesized that nutritional insult in utero might permanently alter mTOR signaling. Mice were fed a low-protein (LP, 8%) or control (C, 20%) diet throughout pregnancy, and offspring examined until 130 days age. Mice receiving LP were born 12% smaller and β-cell mass was significantly reduced throughout life. Islet mTOR levels were lower in LP-exposed mice and localized predominantly to α-rather than β-cells. Incubation of isolated mouse islets with rapamycin significantly reduced cell proliferation while increasing apoptosis. mRNA levels for mTORC complex genes mTOR, Rictor and Raptor were elevated at 7 days in LP mice, as were the mTOR and Raptor proteins. Proglucagon gene expression was similarly increased, but not insulin or the immune/metabolic defense protein STING. In human and mouse pancreas STING was strongly associated with islet β-cells. Results support long-term changes in islet mTOR signaling in response to nutritional insult in utero, with altered expression of glucagon and insulin and a reduced β-cell mass. This may contribute to an increased risk of gestational or type 2 diabetes.
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26
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Takasu T, Takakura S. Protective Effect of Ipragliflozin on Pancreatic Islet Cells in Obese Type 2 Diabetic db/db Mice. Biol Pharm Bull 2018; 41:761-769. [PMID: 29709913 DOI: 10.1248/bpb.b17-01007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ipragliflozin is a selective sodium glucose cotransporter 2 (SGLT2) inhibitor that increases urinary glucose excretion and subsequently improves hyperglycemia in patients with type 2 diabetes mellitus (T2DM). To assess the beneficial effect of ipragliflozin on the mass and function of pancreatic β-cells under diabetic conditions, obese T2DM db/db mice were treated with ipragliflozin for 5 weeks. Glucose and lipid metabolism parameters, pathological changes in pancreatic islet cells and insulin content were evaluated. Pathological examination of pancreatic islet cells comprised measuring the ratios of insulin- and glucagon-positive cells and levels of oxidative stress markers. Hemoglobin A1c, plasma glucose, non-esterified fatty acid and triglyceride levels in ipragliflozin-treated groups were reduced compared to the diabetic control (DM-control) group. Histopathological examination of pancreatic islet cells revealed strong insulin staining and reduced glucagon staining in the ipragliflozin 10 mg/kg-treated group compared with the DM-control group. The ratio of α- to β-cell mass was lower in the ipragliflozin 10 mg/kg-treated group than the DM-control group and was similar to that of the non-diabetic control group. The density of immunostaining for 4-hydroxy-2-nonenal, an oxidative stress marker, in pancreatic islets was significantly lower in the ipragliflozin 10 mg/kg-treated group than the DM-control group. Pancreatic insulin content tended to be higher in the ipragliflozin-treated groups than the DM-control group. Our findings demonstrate the benefit of ipragliflozin treatment in improving glucolipotoxicity and reducing oxidative stress in pancreatic islet cells. Treatment with ipragliflozin may protect against the progressive loss of islet β-cells in patients with T2DM.
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Affiliation(s)
- Toshiyuki Takasu
- Tsukuba Research Center, Drug Discovery Research, Astellas Pharma Inc
| | - Shoji Takakura
- Tsukuba Research Center, Drug Discovery Research, Astellas Pharma Inc
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27
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Zhou W, Gong L, Li X, Wan Y, Wang X, Li H, Jiang B. Screening key candidate genes and pathways involved in insulinoma by microarray analysis. Medicine (Baltimore) 2018; 97:e10826. [PMID: 29851790 PMCID: PMC6392920 DOI: 10.1097/md.0000000000010826] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Insulinoma is a rare type tumor and its genetic features remain largely unknown. This study aimed to search for potential key genes and relevant enriched pathways of insulinoma.The gene expression data from GSE73338 were downloaded from Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified between insulinoma tissues and normal pancreas tissues, followed by pathway enrichment analysis, protein-protein interaction (PPI) network construction, and module analysis. The expressions of candidate key genes were validated by quantitative real-time polymerase chain reaction (RT-PCR) in insulinoma tissues.A total of 1632 DEGs were obtained, including 1117 upregulated genes and 514 downregulated genes. Pathway enrichment results showed that upregulated DEGs were significantly implicated in insulin secretion, and downregulated DEGs were mainly enriched in pancreatic secretion. PPI network analysis revealed 7 hub genes with degrees more than 10, including GCG (glucagon), GCGR (glucagon receptor), PLCB1 (phospholipase C, beta 1), CASR (calcium sensing receptor), F2R (coagulation factor II thrombin receptor), GRM1 (glutamate metabotropic receptor 1), and GRM5 (glutamate metabotropic receptor 5). DEGs involved in the significant modules were enriched in calcium signaling pathway, protein ubiquitination, and platelet degranulation. Quantitative RT-PCR data confirmed that the expression trends of these hub genes were similar to the results of bioinformatic analysis.The present study demonstrated that candidate DEGs and enriched pathways were the potential critical molecule events involved in the development of insulinoma, and these findings were useful for better understanding of insulinoma genesis.
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Affiliation(s)
- Wuhua Zhou
- Department of Hepatobiliary Pancreatic Surgery, Taihe Hospital
| | - Li Gong
- Department of Endocrinology, Taihe Hospital, Shiyan City, Hubei Province, China
| | - Xuefeng Li
- Department of Endocrinology, Taihe Hospital, Shiyan City, Hubei Province, China
| | - Yunyan Wan
- Department of Hepatobiliary Pancreatic Surgery, Taihe Hospital
| | - Xiangfei Wang
- Department of Hepatobiliary Pancreatic Surgery, Taihe Hospital
| | - Huili Li
- Department of Hepatobiliary Pancreatic Surgery, Taihe Hospital
| | - Bin Jiang
- Department of Hepatobiliary Pancreatic Surgery, Taihe Hospital
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28
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Bozadjieva N, Blandino-Rosano M, Chase J, Dai XQ, Cummings K, Gimeno J, Dean D, Powers AC, Gittes GK, Rüegg MA, Hall MN, MacDonald PE, Bernal-Mizrachi E. Loss of mTORC1 signaling alters pancreatic α cell mass and impairs glucagon secretion. J Clin Invest 2017; 127:4379-4393. [PMID: 29106387 DOI: 10.1172/jci90004] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 09/26/2017] [Indexed: 01/19/2023] Open
Abstract
Glucagon plays a major role in the regulation of glucose homeostasis during fed and fasting states. However, the mechanisms responsible for the regulation of pancreatic α cell mass and function are not completely understood. In the current study, we identified mTOR complex 1 (mTORC1) as a major regulator of α cell mass and glucagon secretion. Using mice with tissue-specific deletion of the mTORC1 regulator Raptor in α cells (αRaptorKO), we showed that mTORC1 signaling is dispensable for α cell development, but essential for α cell maturation during the transition from a milk-based diet to a chow-based diet after weaning. Moreover, inhibition of mTORC1 signaling in αRaptorKO mice and in WT animals exposed to chronic rapamycin administration decreased glucagon content and glucagon secretion. In αRaptorKO mice, impaired glucagon secretion occurred in response to different secretagogues and was mediated by alterations in KATP channel subunit expression and activity. Additionally, our data identify the mTORC1/FoxA2 axis as a link between mTORC1 and transcriptional regulation of key genes responsible for α cell function. Thus, our results reveal a potential function of mTORC1 in nutrient-dependent regulation of glucagon secretion and identify a role for mTORC1 in controlling α cell-mass maintenance.
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Affiliation(s)
- Nadejda Bozadjieva
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Jennifer Chase
- Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Xiao-Qing Dai
- Alberta Diabetes Institute and Department of Pharmacology, Edmonton, Alberta, Canada
| | - Kelsey Cummings
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and
| | - Jennifer Gimeno
- Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Danielle Dean
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, and
| | - Alvin C Powers
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, and.,Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee, USA.,VA Tennessee Valley Healthcare, Nashville, Tennessee, USA
| | - George K Gittes
- Children's Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | | | | | - Patrick E MacDonald
- Alberta Diabetes Institute and Department of Pharmacology, Edmonton, Alberta, Canada
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA.,Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA.,Veterans Affairs Medical Center, Miami, Florida, USA
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29
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Singh VK, Haupt ME, Geller DE, Hall JA, Quintana Diez PM. Less common etiologies of exocrine pancreatic insufficiency. World J Gastroenterol 2017; 23:7059-7076. [PMID: 29093615 PMCID: PMC5656454 DOI: 10.3748/wjg.v23.i39.7059] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 05/27/2017] [Accepted: 06/01/2017] [Indexed: 02/06/2023] Open
Abstract
Exocrine pancreatic insufficiency (EPI), an important cause of maldigestion and malabsorption, results from primary pancreatic diseases or secondarily impaired exocrine pancreatic function. Besides cystic fibrosis and chronic pancreatitis, the most common etiologies of EPI, other causes of EPI include unresectable pancreatic cancer, metabolic diseases (diabetes); impaired hormonal stimulation of exocrine pancreatic secretion by cholecystokinin (CCK); celiac or inflammatory bowel disease (IBD) due to loss of intestinal brush border proteins; and gastrointestinal surgery (asynchrony between motor and secretory functions, impaired enteropancreatic feedback, and inadequate mixing of pancreatic secretions with food). This paper reviews such conditions that have less straightforward associations with EPI and examines the role of pancreatic enzyme replacement therapy (PERT). Relevant literature was identified by database searches. Most patients with inoperable pancreatic cancer develop EPI (66%-92%). EPI occurs in patients with type 1 (26%-57%) or type 2 diabetes (20%-36%) and is typically mild to moderate; by definition, all patients with type 3c (pancreatogenic) diabetes have EPI. EPI occurs in untreated celiac disease (4%-80%), but typically resolves on a gluten-free diet. EPI manifests in patients with IBD (14%-74%) and up to 100% of gastrointestinal surgery patients (47%-100%; dependent on surgical site). With the paucity of published studies on PERT use for these conditions, recommendations for or against PERT use remain ambiguous. The authors conclude that there is an urgent need to conduct robust clinical studies to understand the validity and nature of associations between EPI and medical conditions beyond those with proven mechanisms, and examine the potential role for PERT.
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Affiliation(s)
- Vikesh K Singh
- Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States
| | - Mark E Haupt
- Medical Affairs, AbbVie Inc., North Chicago, IL 60064, United States
| | - David E Geller
- Cystic Fibrosis Clinical Development, AbbVie Inc., North Chicago, IL 60064, United States
| | - Jerry A Hall
- CREON® Clinical Development, AbbVie Inc., North Chicago, IL 60064, United States
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Kawada Y, Asahara SI, Sugiura Y, Sato A, Furubayashi A, Kawamura M, Bartolome A, Terashi-Suzuki E, Takai T, Kanno A, Koyanagi-Kimura M, Matsuda T, Hashimoto N, Kido Y. Histone deacetylase regulates insulin signaling via two pathways in pancreatic β cells. PLoS One 2017; 12:e0184435. [PMID: 28886131 PMCID: PMC5590960 DOI: 10.1371/journal.pone.0184435] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 07/23/2017] [Indexed: 12/23/2022] Open
Abstract
Recent studies demonstrated that insulin signaling plays important roles in the regulation of pancreatic β cell mass, the reduction of which is known to be involved in the development of diabetes. However, the mechanism underlying the alteration of insulin signaling in pancreatic β cells remains unclear. The involvement of epigenetic control in the onset of diabetes has also been reported. Thus, we analyzed the epigenetic control of insulin receptor substrate 2 (IRS2) expression in the MIN6 mouse insulinoma cell line. We found concomitant IRS2 up-regulation and enhanced insulin signaling in MIN6 cells, which resulted in an increase in cell proliferation. The H3K9 acetylation status of the Irs2 promoter was positively associated with IRS2 expression. Treatment of MIN6 cells with histone deacetylase inhibitors led to increased IRS2 expression, but this occurred in concert with low insulin signaling. We observed increased IRS2 lysine acetylation as a consequence of histone deacetylase inhibition, a modification that was coupled with a decrease in IRS2 tyrosine phosphorylation. These results suggest that insulin signaling in pancreatic β cells is regulated by histone deacetylases through two novel pathways affecting IRS2: the epigenetic control of IRS2 expression by H3K9 promoter acetylation, and the regulation of IRS2 activity through protein modification. The identification of the histone deacetylase isoform(s) involved in these mechanisms would be a valuable approach for the treatment of type 2 diabetes.
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Affiliation(s)
- Yukina Kawada
- Division of Metabolism and Disease, Department of Biophysics, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Shun-ichiro Asahara
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yumiko Sugiura
- Division of Metabolism and Disease, Department of Biophysics, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Ayaka Sato
- Medical Technology Major, Faculty of Health Sciences Major, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Ayuko Furubayashi
- Medical Technology Major, Faculty of Health Sciences Major, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Mao Kawamura
- Medical Technology Major, Faculty of Health Sciences Major, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Alberto Bartolome
- Department of Medicine, Columbia University Medical Center, New York, New York, United States of America
| | - Emi Terashi-Suzuki
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomoko Takai
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Ayumi Kanno
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Maki Koyanagi-Kimura
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomokazu Matsuda
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Naoko Hashimoto
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yoshiaki Kido
- Division of Metabolism and Disease, Department of Biophysics, Kobe University Graduate School of Health Sciences, Kobe, Japan
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
- * E-mail:
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31
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Feng AL, Xiang YY, Gui L, Kaltsidis G, Feng Q, Lu WY. Paracrine GABA and insulin regulate pancreatic alpha cell proliferation in a mouse model of type 1 diabetes. Diabetologia 2017; 60:1033-1042. [PMID: 28280900 DOI: 10.1007/s00125-017-4239-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/08/2017] [Indexed: 01/20/2023]
Abstract
AIMS/HYPOTHESIS This study aimed to elucidate the mechanism of increased proliferation of alpha cells in recent-onset type 1 diabetes. Pancreatic beta cells express GAD and produce γ-aminobutyric acid (GABA), which inhibits alpha cell secretion of glucagon. We explored the roles of GABA in alpha cell proliferation in conditions corresponding to type 1 diabetes in a mouse model and in vitro. METHODS Type 1 diabetes was induced by injecting the mice with streptozotocin (STZ). Some of the STZ-injected mice were treated with GABA (10 mg/kg daily) for 12 days. Isolated pancreatic islets were treated with STZ or STZ together with GABA for 2 days. The effects of GABA treatment on STZ-induced alpha cell proliferation in vivo and in vitro were assessed. The effect of muscimol, a GABA receptor agonist, on αTC1-6 cell proliferation was also examined. RESULTS STZ injection substantially decreased levels of GAD, GABA and insulin in pancreatic beta cells 12 h after injection; this was followed by an upsurge of phosphorylated mechanistic target of rapamycin (p-mTOR) in the alpha cells at day 1, and a significant increase in alpha cell mass at day 3. Treating STZ-injected mice with GABA largely restored the immunodetectable levels of insulin and GAD in the beta cells and significantly decreased the number of aldehyde dehydrogenase 1 family, member A3 (ALDH1a3)-positive cells, alpha cell mass and hyperglucagonaemia. STZ treatment also increased alpha cell proliferation in isolated islets, which was reversed by co-treatment with GABA. Muscimol, together with insulin, significantly lowered the level of cytosolic Ca2+ and p-mTOR, and decreased the proliferation rate of αTC1-6 cells. CONCLUSIONS/INTERPRETATION GABA signalling critically controls the alpha cell population in pancreatic islets. Low intraislet GABA may contribute to alpha cell hyperplasia in early type 1 diabetes.
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Affiliation(s)
- Allen L Feng
- Robarts Research Institute, Rome: 7240, University of Western Ontario, 1151 Richmond Street North, London, ON, N6A 5B7, Canada
| | - Yun-Yan Xiang
- Robarts Research Institute, Rome: 7240, University of Western Ontario, 1151 Richmond Street North, London, ON, N6A 5B7, Canada
| | - Le Gui
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Gesthika Kaltsidis
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Qingping Feng
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Wei-Yang Lu
- Robarts Research Institute, Rome: 7240, University of Western Ontario, 1151 Richmond Street North, London, ON, N6A 5B7, Canada.
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.
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Asghar ZA, Cusumano A, Yan Z, Remedi MS, Moley KH. Reduced islet function contributes to impaired glucose homeostasis in fructose-fed mice. Am J Physiol Endocrinol Metab 2017; 312:E109-E116. [PMID: 28028036 PMCID: PMC5336566 DOI: 10.1152/ajpendo.00279.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 12/19/2016] [Accepted: 12/19/2016] [Indexed: 01/09/2023]
Abstract
Increased sugar consumption, particularly fructose, in the form of sweetened beverages and sweeteners in our diet adversely affects metabolic health. Because these effects are associated with features of the metabolic syndrome in humans, the direct effect of fructose on pancreatic islet function is unknown. Therefore, we examined the islet phenotype of mice fed excess fructose. Fructose-fed mice exhibited fasting hyperglycemia and glucose intolerance but not hyperinsulinemia, dyslipidemia, or hyperuricemia. Islet function was impaired, with decreased glucose-stimulated insulin secretion and increased glucagon secretion and high fructose consumption leading to α-cell proliferation and upregulation of the fructose transporter GLUT5, which was localized only in α-cells. Our studies demonstrate that excess fructose consumption contributes to hyperglycemia by affecting both β- and α-cells of islets in mice.
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Affiliation(s)
- Zeenat A Asghar
- Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri; and
| | - Andrew Cusumano
- Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri; and
| | - Zihan Yan
- Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, Missouri
| | - Maria S Remedi
- Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, Missouri
| | - Kelle H Moley
- Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri; and
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Green AD, Vasu S, McClenaghan NH, Flatt PR. Implanting 1.1B4 human β-cell pseudoislets improves glycaemic control in diabetic severe combined immune deficient mice. World J Diabetes 2016; 7:523-533. [PMID: 27895821 PMCID: PMC5107712 DOI: 10.4239/wjd.v7.i19.523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 06/01/2016] [Accepted: 08/31/2016] [Indexed: 02/05/2023] Open
Abstract
AIM To investigate the potential of implanting pseudoislets formed from human insulin-releasing β-cell lines as an alternative to islet transplantation.
METHODS In this study, the anti-diabetic potential of novel human insulin releasing 1.1B4 β-cells was evaluated by implanting the cells, either as free cell suspensions, or as three-dimensional pseudoislets, into the subscapular region of severe combined immune deficient mice rendered diabetic by single high-dose administration of streptozotocin. Metabolic parameters including food and fluid intake, bodyweight and blood glucose were monitored throughout the study. At the end of the study animals were given an intraperitoneal glucose tolerance test. Animals were then culled and blood and tissues were collected for analysis. Insulin and glucagon contents of plasma and tissues were measured by insulin radioimmunoassay and chemiluminescent enzyme-linked immunosorbance assay respectively. Histological analyses of pancreatic islets were carried out by quantitative fluorescence immunohistochemistry staining.
RESULTS Both pseudoislet and cell suspension implants yielded well vascularised β-cell masses of similar insulin content. This was associated with progressive amelioration of hyperphagia (P < 0.05), polydipsia (P < 0.05), body weight loss (P < 0.05), hypoinsulinaemia (P < 0.05), hyperglycaemia (P < 0.05 - P < 0.001) and glucose tolerance (P < 0.01). Islet morphology was also significantly improved in both groups of transplanted mice, with increased β-cell (P < 0.05 - P < 0.001) and decreased alpha cell (P < 0.05 - P < 0.001) areas. Whereas mice receiving 1.1B4 cell suspensions eventually exhibited hypoglycaemic complications, pseudoislet recipients displayed a more gradual amelioration of diabetes, and achieved stable blood glucose control similar to non-diabetic mice at the end of the study.
CONCLUSION Although further work is needed to address safety issues, these results provide proof of concept for possible therapeutic applicability of human β-cell line pseudoislets in diabetes.
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β-Cell-Specific Mafk Overexpression Impairs Pancreatic Endocrine Cell Development. PLoS One 2016; 11:e0150010. [PMID: 26901059 PMCID: PMC4763111 DOI: 10.1371/journal.pone.0150010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 02/08/2016] [Indexed: 01/20/2023] Open
Abstract
The MAF family transcription factors are homologs of v-Maf, the oncogenic component of the avian retrovirus AS42. They are subdivided into 2 groups, small and large MAF proteins, according to their structure, function, and molecular size. MAFK is a member of the small MAF family and acts as a dominant negative form of large MAFs. In previous research we generated transgenic mice that overexpress MAFK in order to suppress the function of large MAF proteins in pancreatic β-cells. These mice developed hyperglycemia in adulthood due to impairment of glucose-stimulated insulin secretion. The aim of the current study is to examine the effects of β-cell-specific Mafk overexpression in endocrine cell development. The developing islets of Mafk-transgenic embryos appeared to be disorganized with an inversion of total numbers of insulin+ and glucagon+ cells due to reduced β-cell proliferation. Gene expression analysis by quantitative RT-PCR revealed decreased levels of β-cell-related genes whose expressions are known to be controlled by large MAF proteins. Additionally, these changes were accompanied with a significant increase in key β-cell transcription factors likely due to compensatory mechanisms that might have been activated in response to the β-cell loss. Finally, microarray comparison of gene expression profiles between wild-type and transgenic pancreata revealed alteration of some uncharacterized genes including Pcbd1, Fam132a, Cryba2, and Npy, which might play important roles during pancreatic endocrine development. Taken together, these results suggest that Mafk overexpression impairs endocrine development through a regulation of numerous β-cell-related genes. The microarray analysis provided a unique data set of differentially expressed genes that might contribute to a better understanding of the molecular basis that governs the development and function of endocrine pancreas.
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Angptl4 links α-cell proliferation following glucagon receptor inhibition with adipose tissue triglyceride metabolism. Proc Natl Acad Sci U S A 2015; 112:15498-503. [PMID: 26621734 DOI: 10.1073/pnas.1513872112] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Type 2 diabetes is characterized by a reduction in insulin function and an increase in glucagon activity that together result in hyperglycemia. Glucagon receptor antagonists have been developed as drugs for diabetes; however, they often increase glucagon plasma levels and induce the proliferation of glucagon-secreting α-cells. We find that the secreted protein Angiopoietin-like 4 (Angptl4) is up-regulated via Pparγ activation in white adipose tissue and plasma following an acute treatment with a glucagon receptor antagonist. Induction of adipose angptl4 and Angptl4 supplementation promote α-cell proliferation specifically. Finally, glucagon receptor antagonist improves glycemia in diet-induced obese angptl4 knockout mice without increasing glucagon levels or α-cell proliferation, underscoring the importance of this protein. Overall, we demonstrate that triglyceride metabolism in adipose tissue regulates α-cells in the endocrine pancreas.
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36
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PAX4 Gene Transfer Induces α-to-β Cell Phenotypic Conversion and Confers Therapeutic Benefits for Diabetes Treatment. Mol Ther 2015; 24:251-260. [PMID: 26435408 DOI: 10.1038/mt.2015.181] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 09/25/2015] [Indexed: 12/19/2022] Open
Abstract
The transcription factor Pax4 plays a critical role in the determination of α- versus β-cell lineage during endocrine pancreas development. In this study, we explored whether Pax4 gene transfer into α-cells could convert them into functional β-cells and thus provide therapeutic benefits for insulin-deficient diabetes. We found that Pax4 delivered by adenoviral vector, Ad5.Pax4, induced insulin expression and reduced glucagon expression in αTC1.9 cells. More importantly, these cells exhibited glucose-stimulated insulin secretion, a key feature of functional β-cells. When injected into streptozotocin-induced diabetic mice, Pax4-treated αTC1.9 cells significantly reduced blood glucose, and the mice showed better glucose tolerance, supporting that Pax4 gene transfer into αTC1.9 cells resulted in the formation of functional β-cells. Furthermore, treatment of primary human islets with Ad5.Pax4 resulted in significantly improved β-cell function. Detection of glucagon(+)/Pax4(+)/Insulin(+) cells argued for Pax4-induced α-to-β cell transitioning. This was further supported by quantification of glucagon and insulin bi-hormonal cells, which was significantly higher in Pax4-treated islets than in controls. Finally, direct administration of Ad5.Pax4 into the pancreas of insulin-deficient mice ameliorated hyperglycemia. Taken together, our data demonstrate that manipulating Pax4 gene expression represents a viable therapeutic strategy for the treatment of insulin deficient diabetes.
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Andrzejewski D, Brown ML, Ungerleider N, Burnside A, Schneyer AL. Activins A and B Regulate Fate-Determining Gene Expression in Islet Cell Lines and Islet Cells From Male Mice. Endocrinology 2015; 156:2440-50. [PMID: 25961841 DOI: 10.1210/en.2015-1167] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TGFβ superfamily ligands, receptors, and second messengers, including activins A and B, have been identified in pancreatic islets and proposed to have important roles regulating development, proliferation, and function. We previously demonstrated that Fstl3 (an antagonist of activin activity) null mice have larger islets with β-cell hyperplasia and improved glucose tolerance and insulin sensitivity in the absence of altered β-cell proliferation. This suggested the hypothesis that increased activin signaling influences β-cell expansion by destabilizing the α-cell phenotype and promoting transdifferentiation to β-cells. We tested the first part of this hypothesis by treating α- and β-cell lines and sorted mouse islet cells with activin and related ligands. Treatment of the αTC1-6 α cell line with activins A or B suppressed critical α-cell gene expression, including Arx, glucagon, and MafB while also enhancing β-cell gene expression. In INS-1E β-cells, activin A treatment induced a significant increase in Pax4 (a fate determining β-cell gene) and insulin expression. In sorted primary islet cells, α-cell gene expression was again suppressed by activin treatment in α-cells, whereas Pax4 was enhanced in β-cells. Activin treatment in both cell lines and primary cells resulted in phosphorylated mothers against decapentaplegic-2 phosphorylation. Finally, treatment of αTC1-6 cells with activins A or B significantly inhibited proliferation. These results support the hypothesis that activin signaling destabilized the α-cell phenotype while promoting a β-cell fate. Moreover, these results support a model in which the β-cell expansion observed in Fstl3 null mice may be due, at least in part, to enhanced α- to β-cell transdifferentiation.
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Affiliation(s)
- Danielle Andrzejewski
- Departments of Veterinary and Animal Science (D.A., A.B., A.L.S.) and Nutrition (M.L.B.), and Molecular and Cellular Biology Graduate Program (N.U.), University of Massachusetts-Amherst, Amherst, Massachusetts 01003
| | - Melissa L Brown
- Departments of Veterinary and Animal Science (D.A., A.B., A.L.S.) and Nutrition (M.L.B.), and Molecular and Cellular Biology Graduate Program (N.U.), University of Massachusetts-Amherst, Amherst, Massachusetts 01003
| | - Nathan Ungerleider
- Departments of Veterinary and Animal Science (D.A., A.B., A.L.S.) and Nutrition (M.L.B.), and Molecular and Cellular Biology Graduate Program (N.U.), University of Massachusetts-Amherst, Amherst, Massachusetts 01003
| | - Amy Burnside
- Departments of Veterinary and Animal Science (D.A., A.B., A.L.S.) and Nutrition (M.L.B.), and Molecular and Cellular Biology Graduate Program (N.U.), University of Massachusetts-Amherst, Amherst, Massachusetts 01003
| | - Alan L Schneyer
- Departments of Veterinary and Animal Science (D.A., A.B., A.L.S.) and Nutrition (M.L.B.), and Molecular and Cellular Biology Graduate Program (N.U.), University of Massachusetts-Amherst, Amherst, Massachusetts 01003
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38
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Solloway M, Madjidi A, Gu C, Eastham-Anderson J, Clarke H, Kljavin N, Zavala-Solorio J, Kates L, Friedman B, Brauer M, Wang J, Fiehn O, Kolumam G, Stern H, Lowe J, Peterson A, Allan B. Glucagon Couples Hepatic Amino Acid Catabolism to mTOR-Dependent Regulation of α-Cell Mass. Cell Rep 2015; 12:495-510. [DOI: 10.1016/j.celrep.2015.06.034] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 03/27/2015] [Accepted: 06/09/2015] [Indexed: 02/08/2023] Open
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Pancreatic alpha-cells from female mice undergo morphofunctional changes during compensatory adaptations of the endocrine pancreas to diet-induced obesity. Sci Rep 2015; 5:11622. [PMID: 26108563 PMCID: PMC4650619 DOI: 10.1038/srep11622] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 06/02/2015] [Indexed: 01/28/2023] Open
Abstract
Obesity is frequently associated with insulin resistance. To compensate for this situation and maintain normoglycaemia, pancreatic beta-cells undergo several morphofunctional adaptations, which result in insulin hypersecretion and hyperinsulinaemia. However, no information exists about pancreatic alpha-cells during this compensatory stage of obesity. Here, we studied alpha-cells in mice fed a high-fat diet (HFD) for 12 weeks. These animals exhibited hyperinsulinaemia and normoglycaemia compared with control animals in addition to hypoglucagonaemia. While the in vivo response of glucagon to hypoglycaemia was preserved in the obese mice, the suppression of glucagon secretion during hyperglycaemia was impaired. Additionally, in vitro glucagon release at low glucose levels and glucagon content in isolated islets were decreased, while alpha-cell exocytosis remained unchanged. Assessment of morphological parameters revealed that alpha-cell area was reduced in the pancreas of the obese mice in association with alpha-cell hypotrophy, increased apoptosis and decreased proliferation. HFD feeding for 24 weeks led to significant deterioration in beta-cell function and glucose homeostasis. Under these conditions, the majority of alpha-cell changes were reversed and became comparable to controls. These findings indicate that pancreatic compensatory adaptations during obesity may also involve pancreatic alpha-cells. Additionally, defects in alpha-cell function during obesity may be implicated in progression to diabetes.
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40
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Mohan R, Mao Y, Zhang S, Zhang YW, Xu CR, Gradwohl G, Tang X. Differentially Expressed MicroRNA-483 Confers Distinct Functions in Pancreatic β- and α-Cells. J Biol Chem 2015; 290:19955-66. [PMID: 26109062 DOI: 10.1074/jbc.m115.650705] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Indexed: 01/08/2023] Open
Abstract
Insulin secreted from pancreatic β-cells and glucagon secreted from pancreatic α-cells are the two major hormones working in the pancreas in an opposing manner to regulate and maintain a normal glucose homeostasis. How microRNAs (miRNAs), a population of non-coding RNAs so far demonstrated to be differentially expressed in various types of cells, regulate gene expression in pancreatic β-cells and its closely associated α-cells is not completely clear. In this study, miRNA profiling was performed and compared between pancreatic β-cells and their partner α-cells. One novel miRNA, miR-483, was identified for its highly differential expression in pancreatic β-cells when compared to its expression in α-cells. Overexpression of miR-483 in β-cells increased insulin transcription and secretion by targeting SOCS3, a member of suppressor of cytokine signaling family. In contrast, overexpression of miR-483 decreased glucagon transcription and secretion in α-cells. Moreover, overexpressed miR-483 protected against proinflammatory cytokine-induced apoptosis in β-cells. This correlates with a higher expression level of miR-483 and the expanded β-cell mass observed in the islets of prediabetic db/db mice. Together, our data suggest that miR-483 has opposite effects in α- and β-cells by targeting SOCS3, and the imbalance of miR-483 and its targets may play a crucial role in diabetes pathogenesis.
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Affiliation(s)
- Ramkumar Mohan
- From the Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931
| | - Yiping Mao
- From the Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931
| | - Shungang Zhang
- From the Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931
| | - Yu-Wei Zhang
- the College of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China, and
| | - Cheng-Ran Xu
- the College of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China, and
| | - Gérard Gradwohl
- the Institute of Genetics and Molecular and Cellular Biology, Department of Development and Stem cells, University of Strasbourg, 67404 Illkirch, France
| | - Xiaoqing Tang
- From the Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931,
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41
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Hashemi Z, Yang K, Yang H, Jin A, Ozga J, Chan CB. Cooking enhances beneficial effects of pea seed coat consumption on glucose tolerance, incretin, and pancreatic hormones in high-fat-diet-fed rats. Appl Physiol Nutr Metab 2015; 40:323-33. [PMID: 25794240 DOI: 10.1139/apnm-2014-0380] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Pulses, including dried peas, are nutrient- and fibre-rich foods that improve glucose control in diabetic subjects compared with other fibre sources. We hypothesized feeding cooked pea seed coats to insulin-resistant rats would improve glucose tolerance by modifying gut responses to glucose and reducing stress on pancreatic islets. Glucose intolerance induced in male Sprague-Dawley rats with high-fat diet (HFD; 10% cellulose as fibre) was followed by 3 weeks of HFD with fibre (10%) provided by cellulose, raw-pea seed coat (RP), or cooked-pea seed coat (CP). A fourth group consumed low-fat diet with 10% cellulose. Oral and intraperitoneal glucose tolerance tests (oGTT, ipGTT) were done. CP rats had 30% and 50% lower glucose and insulin responses in oGTT, respectively, compared with the HFD group (P < 0.05) but ipGTT was not different. Plasma islet and incretin hormone concentrations were measured. α- and β-cell areas in the pancreas and density of K- and L-cells in jejunum and ileum were quantified. Jejunal expression of hexose transporters was measured. CP feeding increased fasting glucagon-like peptide 1 and glucose-stimulated gastric inhibitory polypeptide responses (P < 0.05), but K- and L-cells densities were comparable to HFD, as was abundance of SGLT1 and GLUT2 mRNA. No significant difference in β-cell area between diet groups was observed. α-cell area was significantly smaller in CP compared with RP rats (P < 0.05). Overall, our results demonstrate that CP feeding can reverse adverse effects of HFD on glucose homeostasis and is associated with enhanced incretin secretion and reduced α-cell abundance.
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Affiliation(s)
- Zohre Hashemi
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2R3, Canada
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42
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Loss of fibroblast growth factor 21 action induces insulin resistance, pancreatic islet hyperplasia and dysfunction in mice. Cell Death Dis 2015; 6:e1707. [PMID: 25811804 PMCID: PMC4385948 DOI: 10.1038/cddis.2015.80] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 01/16/2023]
Abstract
Fibroblast growth factor (FGF) 21 is an endocrine factor that normalizes glucose homeostasis and reduces insulin resistance in diabetes. Although the pancreas is an FGF21 target organ, its role in pancreatic islets remains obscure. This study aimed to elucidate the physiological role of FGF21 in pancreatic islets using FGF21-knockout (FGF21-KO) mice. Twenty-four-week-old male global FGF21-KO mice were used in this study. Glucose and insulin tolerance were assessed. Expression of genes and proteins related to islet function and underlying mechanisms were also examined. Islet morphology and insulin-secreting capacity were further evaluated. FGF21-KO mice exhibited insulin resistance while being normoglycemic, associated with increases in beta-cell proliferation and insulin synthesis, acting as compensatory responses. This phenotype probably results from enhanced growth hormone (GH) sensitivity in FGF21-KO mouse islets. In addition, ex vivo FGF21 treatment in normal C57BL/6J mouse islets reduced GH signaling, probably via upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and cytokine-inducible SH-2 containing (CIS) protein, whereas KO mouse islets displayed reduced PPARγ and CIS expression. FGF21 treatment also reversed GH-induced insulin expression, beta-cell proliferation and GH-impaired glucose-stimulated insulin secretion (GSIS) in islets. Furthermore, distorted islet morphology and impaired GSIS were observed in KO mice, suggestive of islet dysfunction, whereas the enhanced insulin expression and impaired GSIS in FGF21-KO mouse islets could be reversed by blockade of GH signaling. Our data indicate that FGF21 is important in the regulation of beta-cell proliferation and insulin synthesis, probably via modulation of GH signaling. These findings provide evidence that FGF21 is an obligatory metabolic regulator in pancreatic islets and shed new light onto the role of endogenous FGF21 in the pathogenesis of insulin resistance and islet dysfunction.
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43
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Boerner BP, George NM, Mir SU, Sarvetnick NE. WS6 induces both alpha and beta cell proliferation without affecting differentiation or viability. Endocr J 2015; 62:379-86. [PMID: 25739404 PMCID: PMC4876955 DOI: 10.1507/endocrj.ej14-0449] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Agents that stimulate human pancreatic beta cell proliferation are needed to improve diabetes mellitus treatment. Recently, a small molecule, WS6, was observed to stimulate human beta cell proliferation. However, little is known about its other effects on human islets. To better understand the role of WS6 as a possible beta cell regenerative therapy, we carried out in-depth phenotypic analysis of WS6-treated human islets, exploring its effects on non-beta cell proliferation, beta cell differentiation, and islet cell viability. WS6 not only stimulated beta cell proliferation in cultured human islets (in agreement with previous reports), but also human alpha cell proliferation, indicating that WS6 is not a beta cell-specific mitogen. WS6 did not change the proportion of insulin-positive beta cells or the expression of beta cell-specific transcription factors, suggesting that WS6 does not alter beta cell differentiation, and WS6 had no effect on human islet cell apoptosis or viability. In conclusion, WS6 stimulates proliferation of both human beta and alpha cells while maintaining cellular viability and the beta cell differentiated phenotype. These findings expand the literature on WS6 and support the suggestion that WS6 may help increase human islet mass needed for successful treatment of diabetes.
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Affiliation(s)
- Brian P. Boerner
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nicholas M. George
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Shakeel U.R. Mir
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nora E. Sarvetnick
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
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44
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Mezza T, Kulkarni RN. The regulation of pre- and post-maturational plasticity of mammalian islet cell mass. Diabetologia 2014; 57:1291-303. [PMID: 24824733 DOI: 10.1007/s00125-014-3251-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 03/24/2014] [Indexed: 12/17/2022]
Abstract
Regeneration of mature cells that produce functional insulin represents a major focus and a challenge of current diabetes research aimed at restoring beta cell mass in patients with most forms of diabetes, as well as in ageing. The capacity to adapt to diverse physiological states during life and the consequent ability to cope with increased metabolic demands in the normal regulation of glucose homeostasis is a distinctive feature of the endocrine pancreas in mammals. Both beta and alpha cells, and presumably other islet cells, are dynamically regulated via nutrient, neural and/or hormonal activation of growth factor signalling and the post-transcriptional modification of a variety of genes or via the microbiome to continually maintain a balance between regeneration (e.g. proliferation, neogenesis) and apoptosis. Here we review key regulators that determine islet cell mass at different ages in mammals. Understanding the chronobiology and the dynamics and age-dependent processes that regulate the relationship between the different cell types in the overall maintenance of an optimally functional islet cell mass could provide important insights into planning therapeutic approaches to counter and/or prevent the development of diabetes.
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Affiliation(s)
- Teresa Mezza
- Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, 1 Joslin Place, Boston, MA, 02215, USA
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45
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Abstract
Glucose homeostasis is precisely regulated by glucagon and insulin, which are released by pancreatic α- and β-cells, respectively. While β-cells have been the focus of intense research, less is known about α-cell function and the actions of glucagon. In recent years, the study of this endocrine cell type has experienced a renewed drive. The present review contains a summary of established concepts as well as new information about the regulation of α-cells by glucose, amino acids, fatty acids and other nutrients, focusing especially on glucagon release, glucagon synthesis and α-cell survival. We have also discussed the role of glucagon in glucose homeostasis and in energy and lipid metabolism as well as its potential as a modulator of food intake and body weight. In addition to the well-established action on the liver, we discuss the effects of glucagon in other organs, where the glucagon receptor is expressed. These tissues include the heart, kidneys, adipose tissue, brain, small intestine and the gustatory epithelium. Alterations in α-cell function and abnormal glucagon concentrations are present in diabetes and are thought to aggravate the hyperglycaemic state of diabetic patients. In this respect, several experimental approaches in diabetic models have shown important beneficial results in improving hyperglycaemia after the modulation of glucagon secretion or action. Moreover, glucagon receptor agonism has also been used as a therapeutic strategy to treat obesity.
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46
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Jones HB, Reens J, Brocklehurst SR, Betts CJ, Bickerton S, Bigley AL, Jenkins RP, Whalley NM, Morgan D, Smith DM. Islets of Langerhans from prohormone convertase-2 knockout mice show α-cell hyperplasia and tumorigenesis with elevated α-cell neogenesis. Int J Exp Pathol 2014; 95:29-48. [PMID: 24456331 DOI: 10.1111/iep.12066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 11/14/2013] [Indexed: 01/24/2023] Open
Abstract
Antagonism of the effects of glucagon as an adjunct therapy with other glucose-lowering drugs in the chronic treatment of diabetes has been suggested to aggressively control blood glucose levels. Antagonism of glucagon effects, by targeting glucagon secretion or disabling the glucagon receptor, is associated with α-cell hyperplasia. We evaluated the influence of total glucagon withdrawal on islets of Langerhans using prohormone convertase-2 knockout mice (PC2-ko), in which α-cell hyperplasia is present from a young age and persists throughout life, in order to understand whether or not sustained glucagon deficit would lead to islet tumorigenesis. PC2-ko and wild-type (WT) mice were maintained drug-free, and cohorts of these groups sampled at 3, 12 and 18 months for plasma biochemical and morphological (histological, immunohistochemical, electron microscopical and image analytical) assessments. WT mice showed no islet tumours up to termination of the study, but PC2-ko animals displayed marked changes in islet morphology from α-cell hypertrophy/hyperplasia/atypical hyperplasia, to adenomas and carcinomas, these latter being first encountered at 6-8 months. Islet hyperplasias and tumours primarily consisted of α-cells associated to varying degrees with other islet endocrine cell types. In addition to substantial increases in islet neoplasia, increased α-cell neogenesis associated primarily with pancreatic duct(ule)s was present. We conclude that absolute blockade of the glucagon signal results in tumorigenesis and that the PC2-ko mouse represents a valuable model for investigation of islet tumours and pancreatic ductal neogenesis.
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Affiliation(s)
- Huw B Jones
- Department of Pathological Sciences, AstraZeneca Pharmaceuticals, Macclesfield, Cheshire, UK
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Abstract
Islets form in the pancreas after the first endocrine cells have arisen as either single cells or small cell clusters in the epithelial cords. These cords constitute the developing pancreas in one of its earliest recognizable stages. Islet formation begins at the time the cords transform into a branching ductal system, continues while the ductal system expands, and finally stops before the exocrine tissue of ducts and acini reaches its final expansion. Thus, islets continuously arise from founder cells located in the branching and ramifying ducts. Islets arising from proximal duct cells locate between the exocrine lobules, develop strong autonomic and sensory innervations, and pass their blood to efferent veins (insulo-venous efferent system). Islets arising from cells of more distal ducts locate within the exocrine lobules, respond to nerve impulses ending at neighbouring blood vessels, and pass their blood to the surrounding acini (insulo-acinar portal system). Consequently, the section of the ductal system from which an islet arises determines to a large extent its future neighbouring tissue, architecture, properties, and functions. We note that islets interlobular in position are frequently found in rodents (rats and mice), whereas intralobularly-located, peripheral duct islets prevail in humans and cattle. Also, we expound on bovine foetal Laguesse islets as a prominent foetal type of type 1 interlobular neuro-insular complexes, similar to neuro-insular associations frequently found in rodents. Finally, we consider the probable physiological and pathophysiological implications of the different islet positions within and between species.
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Fiori JL, Shin YK, Kim W, Krzysik-Walker SM, González-Mariscal I, Carlson OD, Sanghvi M, Moaddel R, Farhang K, Gadkaree SK, Doyle ME, Pearson KJ, Mattison JA, de Cabo R, Egan JM. Resveratrol prevents β-cell dedifferentiation in nonhuman primates given a high-fat/high-sugar diet. Diabetes 2013; 62:3500-13. [PMID: 23884882 PMCID: PMC3781448 DOI: 10.2337/db13-0266] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Eating a "Westernized" diet high in fat and sugar leads to weight gain and numerous health problems, including the development of type 2 diabetes mellitus (T2DM). Rodent studies have shown that resveratrol supplementation reduces blood glucose levels, preserves β-cells in islets of Langerhans, and improves insulin action. Although rodent models are helpful for understanding β-cell biology and certain aspects of T2DM pathology, they fail to reproduce the complexity of the human disease as well as that of nonhuman primates. Rhesus monkeys were fed a standard diet (SD), or a high-fat/high-sugar diet in combination with either placebo (HFS) or resveratrol (HFS+Resv) for 24 months, and pancreata were examined before overt dysglycemia occurred. Increased glucose-stimulated insulin secretion and insulin resistance occurred in both HFS and HFS+Resv diets compared with SD. Although islet size was unaffected, there was a significant decrease in β-cells and an increase in α-cells containing glucagon and glucagon-like peptide 1 with HFS diets. Islets from HFS+Resv monkeys were morphologically similar to SD. HFS diets also resulted in decreased expression of essential β-cell transcription factors forkhead box O1 (FOXO1), NKX6-1, NKX2-2, and PDX1, which did not occur with resveratrol supplementation. Similar changes were observed in human islets where the effects of resveratrol were mediated through Sirtuin 1. These findings have implications for the management of humans with insulin resistance, prediabetes, and diabetes.
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Affiliation(s)
- Jennifer L. Fiori
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Yu-Kyong Shin
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
- Biochemistry Department, Boston University School of Medicine, Boston, Massachusetts
| | - Wook Kim
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
- Department of Molecular Science and Technology, Ajou University, Suwon, Republic of Korea
| | - Susan M. Krzysik-Walker
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Isabel González-Mariscal
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Olga D. Carlson
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Mitesh Sanghvi
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Ruin Moaddel
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Kathleen Farhang
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Shekhar K. Gadkaree
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Maire E. Doyle
- Division of Endocrinology, Johns Hopkins Bayview Medical Center, Baltimore, Maryland
| | - Kevin J. Pearson
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
- Graduate Center for Nutritional Sciences, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Julie A. Mattison
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Josephine M. Egan
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
- Corresponding author: Josephine M. Egan,
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49
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Cerf ME. Beta cell dynamics: beta cell replenishment, beta cell compensation and diabetes. Endocrine 2013; 44:303-11. [PMID: 23483434 DOI: 10.1007/s12020-013-9917-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 03/01/2013] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes, characterized by persistent hyperglycemia, arises mostly from beta cell dysfunction and insulin resistance and remains a highly complex metabolic disease due to various stages in its pathogenesis. Glucose homeostasis is primarily regulated by insulin secretion from the beta cells in response to prevailing glycemia. Beta cell populations are dynamic as they respond to fluctuating insulin demand. Beta cell replenishment and death primarily regulate beta cell populations. Beta cells, pancreatic cells, and extra-pancreatic cells represent the three tiers for replenishing beta cells. In rodents, beta cell self-replenishment appears to be the dominant source for new beta cells supported by pancreatic cells (non-beta islet cells, acinar cells, and duct cells) and extra-pancreatic cells (liver, neural, and stem/progenitor cells). In humans, beta cell neogenesis from non-beta cells appears to be the dominant source of beta cell replenishment as limited beta cell self-replenishment occurs particularly in adulthood. Metabolic states of increased insulin demand trigger increased insulin synthesis and secretion from beta cells. Beta cells, therefore, adapt to support their physiology. Maintaining physiological beta cell populations is a strategy for targeting metabolic states of persistently increased insulin demand as in diabetes.
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Affiliation(s)
- Marlon E Cerf
- Diabetes Discovery Platform, South African Medical Research, PO Box 19070, Tygerberg, 7505, South Africa,
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Frantz EDC, Crespo-Mascarenhas C, Barreto-Vianna ARC, Aguila MB, Mandarim-de-Lacerda CA. Renin-angiotensin system blockers protect pancreatic islets against diet-induced obesity and insulin resistance in mice. PLoS One 2013; 8:e67192. [PMID: 23894285 PMCID: PMC3718820 DOI: 10.1371/journal.pone.0067192] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 05/15/2013] [Indexed: 12/29/2022] Open
Abstract
Background The associations between obesity, hypertension and diabetes are well established, and the renin-angiotensin system (RAS) may provide a link among them. The effect of RAS inhibition on type 2 diabetes is still unclear; however, RAS seems to play an important role in the regulation of the pancreas and glucose intolerance of mice fed high-fat (HF) diet. Methods C57BL/6 mice fed a HF diet (8 weeks) were treated with aliskiren (50 mg/kg/day), enalapril (30 mg/kg/day) or losartan (10 mg/kg/day) for 6 weeks, and the protective effects were extensively compared among groups by morphometry, stereological tools, immunostaining, Western blotting and hormonal analysis. Results All RAS inhibitors significantly attenuated the increased blood pressure in mice fed a HF diet. Treatment with enalapril, but not aliskiren or losartan, significantly attenuated body mass (BM) gain, glucose intolerance and insulin resistance, improved the alpha and beta cell mass and prevented the reduction of plasma adiponectin. Furthermore, enalapril treatment improved the protein expression of the pancreatic islet Pdx1, GLUT2, ACE2 and Mas receptors. Losartan treatment showed the greatest AT2R expression. Conclusion Our findings indicate that ACE inhibition with enalapril attenuated several of the deleterious effects of the HF diet. In summary, enalapril appears to be responsible for the normalization of islet morphology and function, of alpha and beta cell mass and of Pdx1 and GLUT2 expression. These protective effects of enalapril were attributed, primarily, to the reduction in body mass gain and food intake and the enhancement of the ACE2/Ang (1-7) /Mas receptor axis and adiponectin levels.
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Affiliation(s)
- Eliete Dalla Corte Frantz
- Laboratory of Morphometry, Metabolism and Cardiovascular Disease, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Camila Crespo-Mascarenhas
- Laboratory of Morphometry, Metabolism and Cardiovascular Disease, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Andre Rodrigues C. Barreto-Vianna
- Laboratory of Morphometry, Metabolism and Cardiovascular Disease, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marcia Barbosa Aguila
- Laboratory of Morphometry, Metabolism and Cardiovascular Disease, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carlos Alberto Mandarim-de-Lacerda
- Laboratory of Morphometry, Metabolism and Cardiovascular Disease, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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