1
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McGlone ER, Bloom SR, Tan TMM. Glucagon resistance and metabolic-associated steatotic liver disease: a review of the evidence. J Endocrinol 2024; 261:e230365. [PMID: 38579751 PMCID: PMC11067060 DOI: 10.1530/joe-23-0365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 04/03/2024] [Indexed: 04/07/2024]
Abstract
Metabolic-associated steatotic liver disease (MASLD) is closely associated with obesity. MASLD affects over 1 billion adults globally but there are few treatment options available. Glucagon is a key metabolic regulator, and its actions include the reduction of liver fat through direct and indirect means. Chronic glucagon signalling deficiency is associated with hyperaminoacidaemia, hyperglucagonaemia and increased circulating levels of glucagon-like peptide 1 (GLP-1) and fibroblast growth factor 21 (FGF-21). Reduction in glucagon activity decreases hepatic amino acid and triglyceride catabolism; metabolic effects include improved glucose tolerance, increased plasma cholesterol and increased liver fat. Conversely, glucagon infusion in healthy volunteers leads to increased hepatic glucose output, decreased levels of plasma amino acids and increased urea production, decreased plasma cholesterol and increased energy expenditure. Patients with MASLD share many hormonal and metabolic characteristics with models of glucagon signalling deficiency, suggesting that they could be resistant to glucagon. Although there are few studies of the effects of glucagon infusion in patients with obesity and/or MASLD, there is some evidence that the expected effect of glucagon on amino acid catabolism may be attenuated. Taken together, this evidence supports the notion that glucagon resistance exists in patients with MASLD and may contribute to the pathogenesis of MASLD. Further studies are warranted to investigate the direct effects of glucagon on metabolism in patients with MASLD.
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Affiliation(s)
- Emma Rose McGlone
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Stephen R Bloom
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Tricia M-M Tan
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
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2
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Lee H, Gao Y, Kim JK, Shin S, Choi M, Hwang Y, Lee S, Rhyu DY, Kim KT. Synergetic effects of concurrent chronic exposure to a mixture of OCPs and high-fat diets on type 2 diabetes and beneficial effects of caloric restriction in female zebrafish. JOURNAL OF HAZARDOUS MATERIALS 2023; 446:130659. [PMID: 36587596 DOI: 10.1016/j.jhazmat.2022.130659] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
This study aimed to investigate the relationship among chronic exposure to a low concentration of organochlorine pesticides (OCPs), high-fat diet (HFD)-induced obesity, and caloric restriction in type 2 diabetes (T2D). Thus, female zebrafish were divided into four groups and treated for 12 weeks as follows: (i) negative control, (ii) HFD (obesity) control, (iii) obesity + a mixture of OCPs (OP), and (iv) obesity + a mixture of OCPs + caloric restriction (OPR). We then assessed T2D-related effects via hematological analysis, histopathology, mitochondrial evaluation, and multiomics analyses. The OP group showed a significant increase in glucose levels, whereas the OPR group maintained glucose at nonsignificant levels. Multiomics analyses revealed that the exacerbated metabolic effects in the OP group were associated with molecular alterations in oxidative stress, inflammation, nucleotide metabolism, and glucose/lipid homeostasis. These alterations were histologically verified by the increased numbers of hypertrophic adipocytes and inflammatory cells observed. Caloric restriction activated pathways related to antioxidant response, mitochondrial fatty acid oxidation, and energy metabolism in zebrafish, leading to preserved glucose homeostasis. In conclusion, this study identified molecular mechanisms underlying the synergistic effect of concurrent exposure to a mixture of OCPs and HFD as well as shed light on the beneficial effect of regular caloric restriction in T2D development.
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Affiliation(s)
- Hyojin Lee
- Department of Environmental Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Yan Gao
- BK21 Plus KNU Multi-Omics Based Creative Drug Research Team, College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 41566, Republic of Korea; Department of Core Analytical Service, Wuxi AppTec, Shanghai 200131, China
| | - Jae Kwan Kim
- Korea Basic Science Institute, Seoul 02841, Republic of Korea
| | - Sooim Shin
- Department of Biotechnology and Bioengineering, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Moonsung Choi
- Department of Optometry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Youngja Hwang
- Metabolomics Laboratory, College of Pharmacy, Korea University, Sejong City 30019, Republic of Korea
| | - Sangkyu Lee
- BK21 Plus KNU Multi-Omics Based Creative Drug Research Team, College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 41566, Republic of Korea; Mass Spectrometry Based Convergence Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Dong Young Rhyu
- Department of Biomedicine, Health & Life Convergence Sciences, BK21 FOUR, Mokpo National University, Jeonnam 58554, Republic of Korea
| | - Ki-Tae Kim
- Department of Environmental Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea.
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Arble DM, Hutch CR, Hafner H, Stelmak D, Leix K, Sorrell J, Pressler JW, Gregg B, Sandoval DA. The role of preproglucagon peptides in regulating β-cell morphology and responses to streptozotocin-induced diabetes. Am J Physiol Endocrinol Metab 2023; 324:E217-E225. [PMID: 36652401 PMCID: PMC9970646 DOI: 10.1152/ajpendo.00152.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 11/29/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023]
Abstract
Insulin secretion from β-cells is tightly regulated by local signaling from preproglucagon (Gcg) products from neighboring α-cells. Physiological paracrine signaling within the microenvironment of the β-cell is altered after metabolic stress, such as high-fat diet or the β-cell toxin, streptozotocin (STZ). Here, we examined the role and source of Gcg peptides in β-cell function and in response to STZ-induced hyperglycemia. We used whole body Gcg null (GcgNull) mice and mice with Gcg expression either specifically within the pancreas (GcgΔPanc) or the intestine (GcgΔIntest). With lower doses of STZ exposure, insulin levels were greater and glucose levels were lower in GcgNull mice compared with wild-type mice. When Gcg was functional only in the intestine, plasma glucagon-like peptide-1 (GLP-1) levels were fully restored but these mice did not have any additional protection from STZ-induced diabetes. Pancreatic Gcg reactivation normalized the hyperglycemic response to STZ. In animals not treated with STZ, GcgNull mice had increased pancreas mass via both α- and β-cell hyperplasia and reactivation of Gcg in the intestine normalized β- but not α-cell mass, whereas pancreatic reactivation normalized both β- and α-cell mass. GcgNull and GcgΔIntest mice maintained higher β-cell mass after treatment with STZ compared with control and GcgΔPanc mice. Although in vivo insulin response to glucose was normal, global lack of Gcg impaired glucose-stimulated insulin secretion in isolated islets. Congenital replacement of Gcg either in the pancreas or intestine normalized glucose-stimulated insulin secretion. Interestingly, mice that had intestinal Gcg reactivated in adulthood had impaired insulin response to KCl. We surmise that the expansion of β-cell mass in the GcgNull mice compensated for decreased individual β-cell insulin secretion, which is sufficient to normalize glucose under physiological conditions and conferred some protection after STZ-induced diabetes.NEW & NOTEWORTHY We examined the role of Gcg on β-cell function under normal and high glucose conditions. GcgNull mice had decreased glucose-stimulated insulin secretion, increased β-cell mass, and partial protection against STZ-induced hyperglycemia. Expression of Gcg within the pancreas normalized these endpoints. Intestinal expression of Gcg only normalized β-cell mass and glucose-stimulated insulin secretion. Increased β-cell mass in GcgNull mice likely compensated for decreased insulin secretion normalizing physiological glucose levels and conferring some protection after STZ-induced diabetes.
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Affiliation(s)
- Deanna M Arble
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, United States
| | - Chelsea R Hutch
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, United States
| | - Hannah Hafner
- Department of Pediatrics, Division of Diabetes, Endocrinology and Metabolism, University of Michigan Medicine, Ann Arbor, Michigan, United States
| | - Daria Stelmak
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, United States
| | - Kyle Leix
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, United States
| | - Joyce Sorrell
- Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, United States
| | - Joshua W Pressler
- Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, United States
| | - Brigid Gregg
- Department of Pediatrics, Division of Diabetes, Endocrinology and Metabolism, University of Michigan Medicine, Ann Arbor, Michigan, United States
| | - Darleen A Sandoval
- Department of Pediatrics, Section of Nutrition and Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
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4
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Habegger KM. Cross Talk Between Insulin and Glucagon Receptor Signaling in the Hepatocyte. Diabetes 2022; 71:1842-1851. [PMID: 35657690 PMCID: PMC9450567 DOI: 10.2337/dbi22-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022]
Abstract
While the consumption of external energy (i.e., feeding) is essential to life, this action induces a temporary disturbance of homeostasis in an animal. A primary example of this effect is found in the regulation of glycemia. In the fasted state, stored energy is released to maintain physiological glycemic levels. Liver glycogen is liberated to glucose, glycerol and (glucogenic) amino acids are used to build new glucose molecules (i.e., gluconeogenesis), and fatty acids are oxidized to fuel long-term energetic demands. This regulation is driven primarily by the counterregulatory hormones epinephrine, growth hormone, cortisol, and glucagon. Conversely, feeding induces a rapid influx of diverse nutrients, including glucose, that disrupt homeostasis. Consistently, a host of hormonal and neural systems under the coordination of insulin are engaged in the transition from fasting to prandial states to reduce this disruption. The ultimate action of these systems is to appropriately store the newly acquired energy and to return to the homeostatic norm. Thus, at first glance it is tempting to assume that glucagon is solely antagonistic regarding the anabolic effects of insulin. We have been intrigued by the role of glucagon in the prandial transition and have attempted to delineate its role as beneficial or inhibitory to glycemic control. The following review highlights this long-known yet poorly understood hormone.
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Affiliation(s)
- Kirk M. Habegger
- Comprehensive Diabetes Center and Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
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5
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Perry RJ. Regulation of Hepatic Lipid and Glucose Metabolism by INSP3R1. Diabetes 2022; 71:1834-1841. [PMID: 35657697 PMCID: PMC9450566 DOI: 10.2337/dbi22-0003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/13/2022] [Indexed: 11/13/2022]
Abstract
With the rising epidemics of obesity and nonalcoholic fatty liver disease (NAFLD) and its downstream consequences including steatohepatitis, cirrhosis, and type 2 diabetes in the U.S. and worldwide, new therapeutic approaches are urgently needed to treat these devastating conditions. Glucagon, known for a century to be a glucose-raising hormone and clearly demonstrated to contribute to fasting and postprandial hyperglycemia in both type 1 and type 2 diabetes, represents an unlikely target to improve health in those with metabolic syndrome. However, recent work from our group and others' identifies an unexpected role for glucagon as a potential means of treating NAFLD, improving insulin sensitivity, and improving the lipid profile. We propose a unifying, calcium-dependent mechanism for glucagon's effects both to stimulate hepatic gluconeogenesis and to enhance hepatic mitochondrial oxidation: signaling through the inositol 1,4,5-trisphosphate receptor type 1 (INSP3R1), glucagon activates phospholipase C (PKC)/protein kinase A (PKA) signaling to enhance adipose triglyceride lipase (ATGL)-dependent intrahepatic lipolysis and, in turn, increase cytosolic gluconeogenesis by allosteric activation of pyruvate carboxylase. Simultaneously in the mitochondria, calcium transferred through mitochondria-associated membranes activates several dehydrogenases in the tricarboxylic acid cycle, correlated with an increase in mitochondrial energy expenditure and reduction in ectopic lipid. This model suggests that short-term, cyclic treatment with glucagon or other INSP3R1 antagonists could hold promise as a means to reset lipid homeostasis in patients with NAFLD.
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Affiliation(s)
- Rachel J. Perry
- Section of Endocrinology & Metabolism, Department of Internal Medicine, and Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT
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6
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Wang R, Ruan L, Jiang G, Li P, Aharodnikau UE, Yunusov KE, Gao X, Solomevich SO. Fabrication of Curcumin-Loaded Silk Fibroin and Polyvinyl Alcohol Composite Hydrogel Films for Skin Wound Healing. ACS APPLIED BIO MATERIALS 2022; 5:4400-4412. [PMID: 36018308 DOI: 10.1021/acsabm.2c00548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Skin regeneration of full-thickness wounds remains a challenge, requiring a well-regulated interplay of cell-cell and cell-matrix signaling. Herein, the composite hydrogel films composed of silk fibroin (SF) and polyvinyl alcohol (PVA) as scaffolds loaded with curcumin nanoparticles (Cur NPs) were developed for skin wound healing. The structure and physicochemical properties of hydrogel films were first evaluated by scanning electron microscopy (SEM), water contact angle, and chemical and mechanical measurements. In addition, the as-fabricated composite hydrogel films have a unique 3D structure and excellent biocompatibility that facilitates the adhesion and growth of cells. Antimicrobial tests in vitro showed that they could inhibit the growth of bacteria due to the incorporation of Cur NPs into composite hydrogel films. The efficacy of the curcumin-loaded SF/PVA composite hydrogel films for skin wound healing was investigated on the skin defect model in vivo. Immunological analysis showed that the as-fabricated Cur NP-loaded SF/PVA composite hydrogel films inhibited inflammation at the wound sites, while promoting angiogenesis during the wound healing process.
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Affiliation(s)
- Ruofan Wang
- Department of Dermatology, Beilun District People's Hospital, Ningbo 315800, China
- School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Liming Ruan
- Department of Dermatology, Beilun District People's Hospital, Ningbo 315800, China
| | - Guohua Jiang
- School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China
- International Scientific and Technological Cooperation Base of Intelligent Biomaterials and Functional Fibers, Hangzhou 310018, China
| | - Pengfei Li
- School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Uladzislau E Aharodnikau
- Research Institute for Physical Chemical Problems of the Belarusian State University, Minsk 220030, Belarus
| | - Khaydar E Yunusov
- Institute of Polymer Chemistry and Physics, Uzbekistan Academy of Sciences, Tashkent 100128, Uzbekistan
| | - Xiaofei Gao
- School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Sergey O Solomevich
- Research Institute for Physical Chemical Problems of the Belarusian State University, Minsk 220030, Belarus
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7
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Holter MM, Saikia M, Cummings BP. Alpha-cell paracrine signaling in the regulation of beta-cell insulin secretion. Front Endocrinol (Lausanne) 2022; 13:934775. [PMID: 35957816 PMCID: PMC9360487 DOI: 10.3389/fendo.2022.934775] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/28/2022] [Indexed: 01/14/2023] Open
Abstract
As an incretin hormone, glucagon-like peptide 1 (GLP-1) lowers blood glucose levels by enhancing glucose-stimulated insulin secretion from pancreatic beta-cells. Therapies targeting the GLP-1 receptor (GLP-1R) use the classical incretin model as a physiological framework in which GLP-1 secreted from enteroendocrine L-cells acts on the beta-cell GLP-1R. However, this model has come into question, as evidence demonstrating local, intra-islet GLP-1 production has advanced the competing hypothesis that the incretin activity of GLP-1 may reflect paracrine signaling of GLP-1 from alpha-cells on GLP-1Rs on beta-cells. Additionally, recent studies suggest that alpha-cell-derived glucagon can serve as an additional, albeit less potent, ligand for the beta-cell GLP-1R, thereby expanding the role of alpha-cells beyond that of a counterregulatory cell type. Efforts to understand the role of the alpha-cell in the regulation of islet function have revealed both transcriptional and functional heterogeneity within the alpha-cell population. Further analysis of this heterogeneity suggests that functionally distinct alpha-cell subpopulations display alterations in islet hormone profile. Thus, the role of the alpha-cell in glucose homeostasis has evolved in recent years, such that alpha-cell to beta-cell communication now presents a critical axis regulating the functional capacity of beta-cells. Herein, we describe and integrate recent advances in our understanding of the impact of alpha-cell paracrine signaling on insulin secretory dynamics and how this intra-islet crosstalk more broadly contributes to whole-body glucose regulation in health and under metabolic stress. Moreover, we explore how these conceptual changes in our understanding of intra-islet GLP-1 biology may impact our understanding of the mechanisms of incretin-based therapeutics.
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Affiliation(s)
- Marlena M. Holter
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- *Correspondence: Marlena M. Holter,
| | - Mridusmita Saikia
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Bethany P. Cummings
- School of Medicine, Department of Surgery, Center for Alimentary and Metabolic Sciences, University of California, Davis, Sacramento, CA, United States
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8
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Bethea M, Bozadjieva-Kramer N, Sandoval DA. Preproglucagon Products and Their Respective Roles Regulating Insulin Secretion. Endocrinology 2021; 162:6329397. [PMID: 34318874 PMCID: PMC8375443 DOI: 10.1210/endocr/bqab150] [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: 05/24/2021] [Indexed: 11/19/2022]
Abstract
Historically, intracellular function and metabolic adaptation within the α-cell has been understudied, with most of the attention being placed on the insulin-producing β-cells due to their role in the pathophysiology of type 2 diabetes mellitus. However, there is a growing interest in understanding the function of other endocrine cell types within the islet and their paracrine role in regulating insulin secretion. For example, there is greater appreciation for α-cell products and their contributions to overall glucose homeostasis. Several recent studies have addressed a paracrine role for α-cell-derived glucagon-like peptide-1 (GLP-1) in regulating glucose homeostasis and responses to metabolic stress. Further, other studies have demonstrated the ability of glucagon to impact insulin secretion by acting through the GLP-1 receptor. These studies challenge the central dogma surrounding α-cell biology describing glucagon's primary role in glucose counterregulation to one where glucagon is critical in regulating both hyper- and hypoglycemic responses. Herein, this review will update the current understanding of the role of glucagon and α-cell-derived GLP-1, placing emphasis on their roles in regulating glucose homeostasis, insulin secretion, and β-cell mass.
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Affiliation(s)
- Maigen Bethea
- Department of Pediatrics, Nutrition Section, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | - Darleen A Sandoval
- Department of Pediatrics, Nutrition Section, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Correspondence: Darleen A. Sandoval, PhD, University of Colorado Anschut, Division of Endocrinology, Metabolism, and Diabetes,12801 E 17th Ave. Research Complex 1 South 7th Floor, Aurora, CO 80045, USA. E-mail:
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9
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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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10
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Rapid gelation of oxidized hyaluronic acid and succinyl chitosan for integration with insulin-loaded micelles and epidermal growth factor on diabetic wound healing. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 117:111273. [PMID: 32919637 DOI: 10.1016/j.msec.2020.111273] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 04/21/2020] [Accepted: 07/04/2020] [Indexed: 12/15/2022]
Abstract
In this work, poly(ethylene glycol)-b-poly[3-acrylamidophenylboronic acid-co-styrene] (PEG-b-P(PBA-co-St) has been firstly synthesized for loading of insulin to form insulin-loaded micelles. Insulin-loaded micelles (ILM) and epidermal growth factor (EGF) are further embedded into the composite hydrogels that can be rapidly gelled by mixing of oxidized hyaluronic acid (OHA) and succinyl chitosan (SCS). Then, the morphology, rheology, degradation, swelling and cytotoxicity properties of the as-prepared composite hydrogels are further investigated to evaluate their physical properties and biocompatibility of as the wound dressing. The as-prepared composite hydrogels show the excellent cell compatibility and low toxicity. To evaluate the wound healing ability of as-prepared composite hydrogels, the tests of wound healing in vivo are conducted on streptozotocin-induced rat models. And the as-prepared composite hydrogels with ILM and EGF show an excellent wound healing performance for promotion of fibroblast proliferation and tissue internal structure integrity, as well as the deposition of collagen and myofibrils. These results suggest that the as-prepared composite hydrogels with loading of ILM and EGF could be a promising candidate for wound healing applications.
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11
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Finan B, Capozzi ME, Campbell JE. Repositioning Glucagon Action in the Physiology and Pharmacology of Diabetes. Diabetes 2020; 69:532-541. [PMID: 31178432 PMCID: PMC7085250 DOI: 10.2337/dbi19-0004] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/30/2019] [Indexed: 01/03/2023]
Abstract
Glucagon is historically described as the counterregulatory hormone to insulin, induced by fasting/hypoglycemia to raise blood glucose through action mediated in the liver. However, it is becoming clear that the biology of glucagon is much more complex and extends beyond hepatic actions to exert control on glucose metabolism. We discuss the inconsistencies with the canonical view that glucagon is primarily a hyperglycemic agent driven by fasting/hypoglycemia and highlight the recent advances that have reshaped the metabolic role of glucagon. These concepts are placed within the context of both normal physiology and the pathophysiology of disease and then extended to discuss emerging strategies that incorporate glucagon agonism in the pharmacology of treating diabetes.
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Affiliation(s)
- Brian Finan
- Novo Nordisk Research Center, Indianapolis, IN
| | - Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University, Durham, NC
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University, Durham, NC
- Division of Endocrinology, Department of Medicine, Duke University, Durham, NC
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
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12
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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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13
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Wang ZJ, Han YF, Zhao F, Yang GZ, Yuan L, Cai HY, Yang JT, Holscher C, Qi JS, Wu MN. A dual GLP-1 and Gcg receptor agonist rescues spatial memory and synaptic plasticity in APP/PS1 transgenic mice. Horm Behav 2020; 118:104640. [PMID: 31765661 DOI: 10.1016/j.yhbeh.2019.104640] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 11/16/2019] [Accepted: 11/16/2019] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease that severely affects the health and lifespan of the elderly worldwide. Recently, the correlation between AD and type 2 diabetes mellitus (T2DM) has received intensive attention, and a promising new anti-AD strategy is the use of anti-diabetic drugs. Oxyntomodulin (Oxm) is a peptide hormone and growth factor that acts on neurons in the hypothalamus. OXM activates glucagon-like peptide 1 (GLP-1) and glucagon (Gcg) receptors, facilitates insulin signaling and has neuroprotective effects against Aβ1-42-induced cytotoxicity in primary hippocampal neurons. Here, we tested the effects of the protease-resistant analogue (D-Ser2)Oxm on spatial memory and synaptic plasticity and the underlying molecular mechanisms in the APP/PS1 transgenic mouse model of AD. The results showed that (D-Ser2)Oxm not only alleviated the impairments of working memory and long-term spatial memory, but also reduced the number of Aβ plaques in the hippocampus, and reversed the suppression of hippocampal synaptic long-term potentiation (LTP). Moreover, (D-Ser2)Oxm administration significantly increased p-PI3K/p-AKT1 expression and decreased p-GSK3β levels in the hippocampus. These results are the first to show an in vivo neuroprotective role of (D-Ser2)Oxm in APP/PS1 mice, and this role involves the improvement of synaptic plasticity, clearance of Aβ and normalization of PI3K/AKT/GSK3β cell signaling in the hippocampus. This study suggests that (D-Ser2)Oxm holds promise for the prevention and treatment of AD.
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Affiliation(s)
- Zhao-Jun Wang
- Department of Physiology, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, PR China
| | - Yu-Fei Han
- Guangzhou Kingmed Diagnostics, Guangzhou, PR China
| | - Fang Zhao
- Department of Physiology, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, PR China
| | - Guang-Zhao Yang
- Department of Cardiovascular Medicine, The First Hospital of Shanxi Medical University, Taiyuan, PR China
| | - Li Yuan
- Department of Physiology, Changzhi Medical College, Changzhi, PR China
| | - Hong-Yan Cai
- Department of Microbiology and Immunology, Shanxi Medical University, Taiyuan, PR China
| | - Jun-Ting Yang
- Department of Physiology, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, PR China
| | - Christian Holscher
- Neuroscience research group, Henan university of Chinese medicine, Zhengzhou, PR China
| | - Jin-Shun Qi
- Department of Physiology, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, PR China.
| | - Mei-Na Wu
- Department of Physiology, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, PR China.
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14
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Gilon P. The Role of α-Cells in Islet Function and Glucose Homeostasis in Health and Type 2 Diabetes. J Mol Biol 2020; 432:1367-1394. [PMID: 31954131 DOI: 10.1016/j.jmb.2020.01.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/23/2019] [Accepted: 01/06/2020] [Indexed: 01/09/2023]
Abstract
Pancreatic α-cells are the major source of glucagon, a hormone that counteracts the hypoglycemic action of insulin and strongly contributes to the correction of acute hypoglycemia. The mechanisms by which glucose controls glucagon secretion are hotly debated, and it is still unclear to what extent this control results from a direct action of glucose on α-cells or is indirectly mediated by β- and/or δ-cells. Besides its hyperglycemic action, glucagon has many other effects, in particular on lipid and amino acid metabolism. Counterintuitively, glucagon seems also required for an optimal insulin secretion in response to glucose by acting on its cognate receptor and, even more importantly, on GLP-1 receptors. Patients with diabetes mellitus display two main alterations of glucagon secretion: a relative hyperglucagonemia that aggravates hyperglycemia, and an impaired glucagon response to hypoglycemia. Under metabolic stress states, such as diabetes, pancreatic α-cells also secrete GLP-1, a glucose-lowering hormone, whereas the gut can produce glucagon. The contribution of extrapancreatic glucagon to the abnormal glucose homeostasis is unclear. Here, I review the possible mechanisms of control of glucagon secretion and the role of α-cells on islet function in healthy state. I discuss the possible causes of the abnormal glucagonemia in diabetes, with particular emphasis on type 2 diabetes, and I briefly comment the current antidiabetic therapies affecting α-cells.
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Affiliation(s)
- Patrick Gilon
- Université Catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Avenue Hippocrate 55 (B1.55.06), Brussels, B-1200, Belgium.
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15
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Stern JH, Smith GI, Chen S, Unger RH, Klein S, Scherer PE. Obesity dysregulates fasting-induced changes in glucagon secretion. J Endocrinol 2019; 243:149-160. [PMID: 31454790 PMCID: PMC6994388 DOI: 10.1530/joe-19-0201] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 08/27/2019] [Indexed: 01/06/2023]
Abstract
Hyperglucagonemia, a hallmark in obesity and insulin resistance promotes hepatic glucose output, exacerbating hyperglycemia and thus predisposing to the development type 2 diabetes. As such, glucagon signaling is a key target for new therapeutics to manage insulin resistance. We evaluated glucagon homeostasis in lean and obese mice and people. In lean mice, fasting for 24 h caused a rise in glucagon. In contrast, a decrease in serum glucagon compared to baseline was observed in diet-induced obese mice between 8 and 24 h of fasting. Fasting decreased serum insulin in both lean and obese mice. Accordingly, the glucagon:insulin ratio was unaffected by fasting in obese mice but increased in lean mice. Re-feeding (2 h) restored hyperglucagonemia in obese mice. Pancreatic perfusion studies confirm that fasting (16 h) decreases pancreatic glucagon secretion in obese mice. Consistent with our findings in the mouse, a mixed meal increased serum glucagon and insulin concentrations in obese humans, both of which decreased with time after a meal. Consequently, fasting and re-feeding less robustly affected glucagon:insulin ratios in obese compared to lean participants. The glucoregulatory disturbance in obesity may be driven by inappropriate regulation of glucagon by fasting and a static glucagon:insulin ratio.
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Affiliation(s)
- Jennifer H. Stern
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Gordon I. Smith
- Center for Human Nutrition, Washington University School of Medicine, Saint Louis, MO
| | - Shiuwei Chen
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Roger H. Unger
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, Saint Louis, MO
| | - Philipp E. Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
- Correspondence: , Telephone: (214) 648-8715, Fax: (214) 648-8720
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16
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Brunel FM, Mayer JP, Gelfanov VM, Zaykov AN, Finan B, Perez-Tilve D, DiMarchi RD. A Disulfide Scan of Insulin by [3 + 1] Methodology Exhibits Site-Specific Influence on Bioactivity. ACS Chem Biol 2019; 14:1829-1835. [PMID: 31343157 DOI: 10.1021/acschembio.9b00420] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Insulin is the principal hormone involved in the regulation of metabolism and has served a seminal role in the treatment of diabetes. Building upon advances in insulin synthetic methodology, we have developed a straightforward route to novel insulins containing a fourth disulfide bond in a [3 + 1] fashion establishing the first disulfide scan of the hormone. All the targeted analogs accommodated the constraint to demonstrate an unexpected conformational flexibility of native insulin. The bioactivity was established for the constrained (4-DS) and unconstrained (3-DS) analogs by in vitro methods, and extended to in vivo study for select peptides. We also identified residue B10 as a preferred anchor to introduce a tether that would regulate insulin bioactivity. We believe that the described [3 + 1] methodology might constitute the preferred approach for performing similar disulfide scanning in peptides that contain multiple disulfides.
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Affiliation(s)
- Florence M. Brunel
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
| | - John P. Mayer
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
| | - Vasily M. Gelfanov
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
| | | | - Brian Finan
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
| | - Diego Perez-Tilve
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
| | - Richard D. DiMarchi
- Novo Nordisk Research Center, Indianapolis, Indiana 46241, United States
- Department, of Chemistry,Indiana University, Bloomington, Indiana 47405, United States
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17
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Capozzi ME, Svendsen B, Encisco SE, Lewandowski SL, Martin MD, Lin H, Jaffe JL, Coch RW, Haldeman JM, MacDonald PE, Merrins MJ, D'Alessio DA, Campbell JE. β Cell tone is defined by proglucagon peptides through cAMP signaling. JCI Insight 2019; 4:126742. [PMID: 30720465 DOI: 10.1172/jci.insight.126742] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/29/2019] [Indexed: 01/05/2023] Open
Abstract
Paracrine interactions between pancreatic islet cells have been proposed as a mechanism to regulate hormone secretion and glucose homeostasis. Here, we demonstrate the importance of proglucagon-derived peptides (PGDPs) for α to β cell communication and control of insulin secretion. Signaling through this system occurs through both the glucagon-like peptide receptor (Glp1r) and glucagon receptor (Gcgr). Loss of PGDPs, or blockade of their receptors, decreases insulin secretion in response to both metabolic and nonmetabolic stimulation of mouse and human islets. This effect is due to reduced β cell cAMP and affects the quantity but not dynamics of insulin release, indicating that PGDPs dictate the magnitude of insulin output in an isolated islet. In healthy mice, additional factors that stimulate cAMP can compensate for loss of PGDP signaling; however, input from α cells is essential to maintain glucose tolerance during the metabolic stress induced by high-fat feeding. These findings demonstrate an essential role for α cell regulation of β cells, raising the possibility that abnormal paracrine signaling contributes to impaired insulin secretion in diabetes. Moreover, these findings support reconsideration of the role for α cells in postprandial glucose control.
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Affiliation(s)
- Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA
| | - Berit Svendsen
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA
| | - Sara E Encisco
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA
| | - Sophie L Lewandowski
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Mackenzie D Martin
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA
| | - Haopeng Lin
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Alberta, Canada
| | - Justin L Jaffe
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA
| | - Reilly W Coch
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA.,Department of Medicine and
| | - Jonathan M Haldeman
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA.,Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Patrick E MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Alberta, Canada
| | - Matthew J Merrins
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - David A D'Alessio
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA.,Department of Medicine and
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, USA.,Department of Medicine and.,Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
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