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Abdelrahman Z, Maxwell AP, McKnight AJ. Genetic and Epigenetic Associations with Post-Transplant Diabetes Mellitus. Genes (Basel) 2024; 15:503. [PMID: 38674437 PMCID: PMC11050138 DOI: 10.3390/genes15040503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/10/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Post-transplant diabetes mellitus (PTDM) is a common complication of solid organ transplantation. PTDM prevalence varies due to different diabetes definitions. Consensus guidelines for the diagnosis of PTDM have been published based on random blood glucose levels, glycated hemoglobin (HbA1c), and oral glucose tolerance test (OGTT). The task of diagnosing PTDM continues to pose challenges, given the potential for diabetes to manifest at different time points after transplantation, thus demanding constant clinical vigilance and repeated testing. Interpreting HbA1c levels can be challenging after renal transplantation. Pre-transplant risk factors for PTDM include obesity, sedentary lifestyle, family history of diabetes, ethnicity (e.g., African-Caribbean or South Asian ancestry), and genetic risk factors. Risk factors for PTDM include immunosuppressive drugs, weight gain, hepatitis C, and cytomegalovirus infection. There is also emerging evidence that genetic and epigenetic variation in the organ transplant recipient may influence the risk of developing PTDM. This review outlines many known risk factors for PTDM and details some of the pathways, genetic variants, and epigenetic features associated with PTDM. Improved understanding of established and emerging risk factors may help identify people at risk of developing PTDM and may reduce the risk of developing PTDM or improve the management of this complication of organ transplantation.
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Affiliation(s)
- Zeinab Abdelrahman
- Centre for Public Health, Queen’s University of Belfast, Belfast BT12 6BA, UK; (Z.A.); (A.P.M.)
| | - Alexander Peter Maxwell
- Centre for Public Health, Queen’s University of Belfast, Belfast BT12 6BA, UK; (Z.A.); (A.P.M.)
- Regional Nephrology Unit, Belfast City Hospital, Belfast BT9 7AB, UK
| | - Amy Jayne McKnight
- Centre for Public Health, Queen’s University of Belfast, Belfast BT12 6BA, UK; (Z.A.); (A.P.M.)
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Hill TG, Hill DJ. The Importance of Intra-Islet Communication in the Function and Plasticity of the Islets of Langerhans during Health and Diabetes. Int J Mol Sci 2024; 25:4070. [PMID: 38612880 PMCID: PMC11012451 DOI: 10.3390/ijms25074070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes.
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Affiliation(s)
- Thomas G. Hill
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - David J. Hill
- Lawson Health Research Institute, St. Joseph’s Health Care, London, ON N6A 4V2, Canada;
- Departments of Medicine, Physiology and Pharmacology, Western University, London, ON N6A 3K7, Canada
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3
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Safarzad M, Jazi MS, Kiaei M, Asadi J. Lower serum zinc level is associated with higher fasting insulin in type 2 diabetes mellitus (T2DM) and relates with disturbed glucagon suppression response in male patients. Prim Care Diabetes 2023; 17:493-498. [PMID: 37391316 DOI: 10.1016/j.pcd.2023.05.008] [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: 02/17/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 07/02/2023]
Abstract
AIMS Zinc ion can play critical role in glycemic control in diabetes mellitus (DM), contributing to both insulin synthesis and secretion. In this study, we aimed to investigate the level of zinc in diabetic patients and its association with glycemic parameters, insulin, and glucagon level. METHODS 112 individuals (59 cases of type 2DM and 53 non-diabetic controls) were included in this study. Biochemical parameters (FBG, 2hpp, HbA1C), and zinc level in the serum were measured using colorimetric assays. Insulin and glucagon were measured by ELISA method. HOMA-IR, HOMA-B, reciprocal HOMA-B, and Quicki indices were calculated using appropriate formula. For further analysis, patients were divided into two groups: high (>135.5 μg/dl) and low (<135.5 μg/dl) zinc. Glucagon suppression was considered yes if 2hpp glucagon < fasting glucagon. RESULTS Our results showed that serum Zn level in type 2 DM patients was lower than control (P value=0.02). Patients with lower Zn had higher fasting insulin (P value=0.006) and higher β-cell activity index (HOMA-B, p value=0.02), however fasting glucagon and parameters of hyperglycemia (FBG, 2hpp, Hba1C) were not different. Moreover, insulin sensitivity and resistance indices (Quicki, HOMA-IR,1/HOMA-IR) showed non-significantly improved status in high Zn group. We found non-significant association between glucagon suppression and Zn level in both genders (N = 39, p value = 0.07), however, it was significant in males (N = 14, p value = 0.02). CONCLUSION Altogether, our results indicated reduced serum Zn in type 2DM can exacerbate hyperinsulinemia and glucagon suppression (only significant in the male), highlighting its importance in type 2DM control.
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Affiliation(s)
- Mahdieh Safarzad
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Marie Saghaeian Jazi
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran; Stem Cell Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
| | - Mohammadreza Kiaei
- Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Jahanbakhsh Asadi
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
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Riahi Y, Kogot-Levin A, Kadosh L, Agranovich B, Malka A, Assa M, Piran R, Avrahami D, Glaser B, Gottlieb E, Jackson F, Cerasi E, Bernal-Mizrachi E, Helman A, Leibowitz G. Hyperglucagonaemia in diabetes: altered amino acid metabolism triggers mTORC1 activation, which drives glucagon production. Diabetologia 2023; 66:1925-1942. [PMID: 37480416 DOI: 10.1007/s00125-023-05967-8] [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: 02/22/2023] [Accepted: 06/07/2023] [Indexed: 07/24/2023]
Abstract
AIM/HYPOTHESIS Hyperglycaemia is associated with alpha cell dysfunction, leading to dysregulated glucagon secretion in type 1 and type 2 diabetes; however, the mechanisms involved are still elusive. The nutrient sensor mammalian target of rapamycin complex 1 (mTORC1) plays a major role in the maintenance of alpha cell mass and function. We studied the regulation of alpha cell mTORC1 by nutrients and its role in the development of hyperglucagonaemia in diabetes. METHODS Alpha cell mTORC1 activity was assessed by immunostaining for phosphorylation of its downstream target, the ribosomal protein S6, and glucagon, followed by confocal microscopy on pancreatic sections and flow cytometry on dispersed human and mouse islets and the alpha cell line, αTC1-6. Metabolomics and metabolic flux were studied by 13C glucose labelling in 2.8 or 16.7 mmol/l glucose followed by LC-MS analysis. To study the role of mTORC1 in mediating hyperglucagonaemia in diabetes, we generated an inducible alpha cell-specific Rptor knockout in the Akita mouse model of diabetes and tested the effects on glucose tolerance by IPGTT and on glucagon secretion. RESULTS mTORC1 activity was increased in alpha cells from diabetic Akita mice in parallel to the development of hyperglycaemia and hyperglucagonaemia (two- to eightfold increase). Acute exposure of mouse and human islets to amino acids stimulated alpha cell mTORC1 (3.5-fold increase), whereas high glucose concentrations inhibited mTORC1 (1.4-fold decrease). The mTORC1 response to glucose was abolished in human and mouse diabetic alpha cells following prolonged islet exposure to high glucose levels, resulting in sustained activation of mTORC1, along with increased glucagon secretion. Metabolomics and metabolic flux analysis showed that exposure to high glucose levels enhanced glycolysis, glucose oxidation and the synthesis of glucose-derived amino acids. In addition, chronic exposure to high glucose levels increased the expression of Slc7a2 and Slc38a4, which encode amino acid transporters, as well as the levels of branched-chain amino acids and methionine cycle metabolites (~1.3-fold increase for both). Finally, conditional Rptor knockout in alpha cells from adult diabetic mice inhibited mTORC1, thereby inhibiting glucagon secretion (~sixfold decrease) and improving diabetes, despite persistent insulin deficiency. CONCLUSIONS/INTERPRETATION Alpha cell exposure to hyperglycaemia enhances amino acid synthesis and transport, resulting in sustained activation of mTORC1, thereby increasing glucagon secretion. mTORC1 therefore plays a major role in mediating alpha cell dysfunction in diabetes. DATA AVAILABILITY All sequencing data are available from the Gene Expression Omnibus (GEO) repository (accession no. GSE154126; https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE154126 ).
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Affiliation(s)
- Yael Riahi
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Aviram Kogot-Levin
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Liat Kadosh
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Bella Agranovich
- Laboratory for Metabolism in Health and Disease, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Assaf Malka
- The Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Michael Assa
- The Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Ron Piran
- The Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Dana Avrahami
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Developmental Biology and Cancer Research, Hadassah Medical Center, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Benjamin Glaser
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Eyal Gottlieb
- Laboratory for Metabolism in Health and Disease, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
- Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Fields Jackson
- Department of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Erol Cerasi
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Aharon Helman
- Department of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel.
| | - Gil Leibowitz
- Diabetes Unit, Department of Endocrinology and Metabolism, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.
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Knuth ER, Foster HR, Jin E, Merrins MJ. Leucine suppresses glucagon secretion from pancreatic islets by directly modulating α-cell cAMP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551113. [PMID: 37577685 PMCID: PMC10418066 DOI: 10.1101/2023.07.31.551113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Objective Pancreatic islets are nutrient sensors that regulate organismal blood glucose homeostasis. Glucagon release from the pancreatic α-cell is important under fasted, fed, and hypoglycemic conditions, yet metabolic regulation of α-cells remains poorly understood. Here, we identified a previously unexplored role for physiological levels of leucine, which is classically regarded as a β-cell fuel, in the intrinsic regulation of α-cell glucagon release. Methods GcgCreERT:CAMPER and GcgCreERT:GCaMP6s mice were generated to perform dynamic, high-throughput functional measurements of α-cell cAMP and Ca2+ within the intact islet. Islet perifusion assays were used for simultaneous, time-resolved measurements of glucagon and insulin release from mouse and human islets. The effects of leucine were compared with glucose and the mitochondrial fuels 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH, non-metabolized leucine analog that activates glutamate dehydrogenase), α-ketoisocaproate (KIC, leucine metabolite), and methyl-succinate (complex II fuel). CYN154806 (Sstr2 antagonist), diazoxide (KATP activator, which prevents Ca2+-dependent exocytosis from α, β, and δ-cells), and dispersed α-cells were used to inhibit islet paracrine signaling and identify α-cell intrinsic effects. Results Mimicking the effect of glucose, leucine strongly suppressed amino acid-stimulated glucagon secretion. Mechanistically, leucine dose-dependently reduced α-cell cAMP at physiological concentrations, with an IC50 of 57, 440, and 1162 μM at 2, 6, and 10 mM glucose, without affecting α-cell Ca2+. Leucine also reduced α-cell cAMP in islets treated with Sstr2 antagonist or diazoxide, as well as dispersed α-cells, indicating an α-cell intrinsic effect. The effect of leucine was matched by KIC and the glutamate dehydrogenase activator BCH, but not methyl-succinate, indicating a dependence on mitochondrial anaplerosis. Glucose, which stimulates anaplerosis via pyruvate carboxylase, had the same suppressive effect on α-cell cAMP but with lower potency. Similarly to mouse islets, leucine suppressed glucagon secretion from human islets under hypoglycemic conditions. Conclusions These findings highlight an important role for physiological levels of leucine in the metabolic regulation of α-cell cAMP and glucagon secretion. Leucine functions primarily through an α-cell intrinsic effect that is dependent on glutamate dehydrogenase, in addition to the well-established α-cell regulation by β/δ-cell paracrine signaling. Our results suggest that mitochondrial anaplerosis-cataplerosis facilitates the glucagonostatic effect of both leucine and glucose, which cooperatively suppress α-cell tone by reducing cAMP.
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Affiliation(s)
- Emily R. Knuth
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Hannah R. Foster
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Erli Jin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Matthew J. Merrins
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
- William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
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Alfaro GF, Palombo V, D'Andrea M, Cao W, Zhang Y, Beever J, Muntifering RB, Pacheco WJ, Rodning SP, Wang X, Moisá SJ. Hepatic transcript profiling in beef cattle: Effects of rumen-protected niacin supplementation. PLoS One 2023; 18:e0289409. [PMID: 37535643 PMCID: PMC10399858 DOI: 10.1371/journal.pone.0289409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 07/18/2023] [Indexed: 08/05/2023] Open
Abstract
The objective of our study was to assess the effect of rumen-protected niacin supplementation on the transcriptome of liver tissue in growing Angus × Simmental steers and heifers through RNA-seq analysis. Consequently, we wanted to assess the known role of niacin in the physiological processes of vasodilation, detoxification, and immune function in beef hepatic tissue. Normal weaned calves (~8 months old) were provided either a control diet or a diet supplemented with rumen-protected niacin (6 g/hd/d) for a 30-day period, followed by a liver biopsy. We observed a significant list of changes at the transcriptome level due to rumen-protected niacin supplementation. Several metabolic pathways revealed potential positive effects to the animal's liver metabolism due to administration of rumen-protected niacin; for example, a decrease in lipolysis, apoptosis, inflammatory responses, atherosclerosis, oxidative stress, fibrosis, and vasodilation-related pathways. Therefore, results from our study showed that the liver transcriptional machinery switched several metabolic pathways to a condition that could potentially benefit the health status of animals supplemented with rumen-protected niacin. In conclusion, based on the results of our study, we can suggest the utilization of rumen-protected niacin supplementation as a nutritional strategy could improve the health status of growing beef cattle in different beef production stages, such as backgrounding operations or new arrivals to a feedlot.
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Affiliation(s)
- Gastón F Alfaro
- Department of Animal Sciences, Auburn University, Auburn, AL, United States of America
| | - Valentino Palombo
- Department of Agricultural, Environmental and Food Sciences, Università degli Studi del Molise, Campobasso, Italy
| | - Mariasilvia D'Andrea
- Department of Agricultural, Environmental and Food Sciences, Università degli Studi del Molise, Campobasso, Italy
| | - Wenqi Cao
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States of America
| | - Yue Zhang
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States of America
| | - Jonathan Beever
- Department of Animal Sciences, University of Tennessee, Knoxville, TN, United States of America
| | - Russell B Muntifering
- Department of Animal Sciences, Auburn University, Auburn, AL, United States of America
- Cooperative Extension Service, University of Kentucky, Kentucky, Lexington, United States of America
| | - Wilmer J Pacheco
- Department of Poultry Sciences, Auburn University, Auburn, AL, United States of America
| | - Soren P Rodning
- Department of Animal Sciences, Auburn University, Auburn, AL, United States of America
| | - Xu Wang
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States of America
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, United States of America
| | - Sonia J Moisá
- Department of Animal Sciences, University of Tennessee, Knoxville, TN, United States of America
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Deguchi-Horiuchi H, Suzuki S, Lee EY, Miki T, Yamanaka N, Manabe I, Tanaka T, Yokote K. Pancreatic β-cell glutaminase 2 maintains glucose homeostasis under the condition of hyperglycaemia. Sci Rep 2023; 13:7291. [PMID: 37147373 PMCID: PMC10162969 DOI: 10.1038/s41598-023-34336-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/27/2023] [Indexed: 05/07/2023] Open
Abstract
Glutaminase 2 (GLS2), a master regulator of glutaminolysis that is induced by p53 and converts glutamine to glutamate, is abundant in the liver but also exists in pancreatic β-cells. However, the roles of GLS2 in islets associated with glucose metabolism are unknown, presenting a critical issue. To investigate the roles of GLS2 in pancreatic β-cells in vivo, we generated β-cell-specific Gls2 conditional knockout mice (Gls2 CKO), examined their glucose homeostasis, and validated the findings using a human islet single-cell analysis database. GLS2 expression markedly increased along with p53 in β-cells from control (RIP-Cre) mice fed a high-fat diet. Furthermore, Gls2 CKO exhibited significant diabetes mellitus with gluconeogenesis and insulin resistance when fed a high-fat diet. Despite marked hyperglycaemia, impaired insulin secretion and paradoxical glucagon elevation were observed in high-fat diet-fed Gls2 CKO mice. GLS2 silencing in the pancreatic β-cell line MIN6 revealed downregulation of insulin secretion and intracellular ATP levels, which were closely related to glucose-stimulated insulin secretion. Additionally, analysis of single-cell RNA-sequencing data from human pancreatic islet cells also revealed that GLS2 expression was elevated in β-cells from diabetic donors compared to nondiabetic donors. Consistent with the results of Gls2 CKO, downregulated GLS2 expression in human pancreatic β-cells from diabetic donors was associated with significantly lower insulin gene expression as well as lower expression of members of the insulin secretion pathway, including ATPase and several molecules that signal to insulin secretory granules, in β-cells but higher glucagon gene expression in α-cells. Although the exact mechanism by which β-cell-specific GLS2 regulates insulin and glucagon requires further study, our data indicate that GLS2 in pancreatic β-cells maintains glucose homeostasis under the condition of hyperglycaemia.
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Affiliation(s)
- Hanna Deguchi-Horiuchi
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Diabetes, Metabolism and Endocrinology, Chiba University hospital, Chiba, Japan
| | - Sawako Suzuki
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba University, Chiba, Japan.
- Department of Diabetes, Metabolism and Endocrinology, Chiba University hospital, Chiba, Japan.
| | - Eun Young Lee
- Department of Medical Physiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Takashi Miki
- Department of Medical Physiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Noriko Yamanaka
- Department of Disease Biology and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Ichiro Manabe
- Department of Disease Biology and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Tomoaki Tanaka
- Department of Molecular Diagnosis, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Koutaro Yokote
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Diabetes, Metabolism and Endocrinology, Chiba University hospital, Chiba, Japan
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Hædersdal S, Andersen A, Knop FK, Vilsbøll T. Revisiting the role of glucagon in health, diabetes mellitus and other metabolic diseases. Nat Rev Endocrinol 2023; 19:321-335. [PMID: 36932176 DOI: 10.1038/s41574-023-00817-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/17/2023] [Indexed: 03/19/2023]
Abstract
Insulin and glucagon exert opposing effects on glucose metabolism and, consequently, pancreatic islet β-cells and α-cells are considered functional antagonists. The intra-islet hypothesis has previously dominated the understanding of glucagon secretion, stating that insulin acts to inhibit the release of glucagon. By contrast, glucagon is a potent stimulator of insulin secretion and has been used to test β-cell function. Over the past decade, α-cells have received increasing attention due to their ability to stimulate insulin secretion from neighbouring β-cells, and α-cell-β-cell crosstalk has proven central for glucose homeostasis in vivo. Glucagon is not only the counter-regulatory hormone to insulin in glucose metabolism but also glucagon secretion is more susceptible to changes in the plasma concentration of certain amino acids than to changes in plasma concentrations of glucose. Thus, the actions of glucagon also include a central role in amino acid turnover and hepatic fat oxidation. This Review provides insights into glucagon secretion, with a focus on the local paracrine actions on glucagon and the importance of α-cell-β-cell crosstalk. We focus on dysregulated glucagon secretion in obesity, non-alcoholic fatty liver disease and type 2 diabetes mellitus. Lastly, the future potential of targeting hyperglucagonaemia and applying dual and triple receptor agonists with glucagon receptor-activating properties in combination with incretin hormone receptor agonism is discussed.
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Affiliation(s)
- Sofie Hædersdal
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark.
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark.
| | - Andreas Andersen
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Filip K Knop
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Tina Vilsbøll
- Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark.
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark.
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
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Screening of Metabolism-Disrupting Chemicals on Pancreatic α-Cells Using In Vitro Methods. Int J Mol Sci 2022; 24:ijms24010231. [PMID: 36613676 PMCID: PMC9820113 DOI: 10.3390/ijms24010231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/07/2022] [Accepted: 12/20/2022] [Indexed: 12/25/2022] Open
Abstract
Metabolism-disrupting chemicals (MDCs) are endocrine disruptors with obesogenic and/or diabetogenic action. There is mounting evidence linking exposure to MDCs to increased susceptibility to diabetes. Despite the important role of glucagon in glucose homeostasis, there is little information on the effects of MDCs on α-cells. Furthermore, there are no methods to identify and test MDCs with the potential to alter α-cell viability and function. Here, we used the mouse α-cell line αTC1-9 to evaluate the effects of MDCs on cell viability and glucagon secretion. We tested six chemicals at concentrations within human exposure (from 0.1 pM to 1 µM): bisphenol-A (BPA), tributyltin (TBT), perfluorooctanoic acid (PFOA), triphenylphosphate (TPP), triclosan (TCS), and dichlorodiphenyldichloroethylene (DDE). Using two different approaches, MTT assay and DNA-binding dyes, we observed that BPA and TBT decreased α-cell viability via a mechanism that depends on the activation of estrogen receptors and PPARγ, respectively. These two chemicals induced ROS production, but barely altered the expression of endoplasmic reticulum (ER) stress markers. Although PFOA, TPP, TCS, and DDE did not alter cell viability nor induced ROS generation or ER stress, all four compounds negatively affected glucagon secretion. Our findings suggest that αTC1-9 cells seem to be an appropriate model to test chemicals with metabolism-disrupting activity and that the improvement of the test methods proposed herein could be incorporated into protocols for the screening of diabetogenic MDCs.
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Bosi E, Marchetti P, Rutter GA, Eizirik DL. Human alpha cell transcriptomic signatures of types 1 and 2 diabetes highlight disease-specific dysfunction pathways. iScience 2022; 25:105056. [PMID: 36134336 PMCID: PMC9483809 DOI: 10.1016/j.isci.2022.105056] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 06/10/2022] [Accepted: 08/26/2022] [Indexed: 01/24/2023] Open
Abstract
Although glucagon secretion is perturbed in both T1D and T2D, the pathophysiological changes in individual pancreatic alpha cells are still obscure. Using recently curated single-cell RNASeq data from T1D or T2D donors and their controls, we identified alpha cell transcriptomic alterations consistent with both common and discrete pathways. Although alterations in alpha cell identity gene (ARX, MAFB) expression were conserved, cytokine-regulated genes and genes involved in glucagon biosynthesis and processing were up-regulated in T1D. Conversely, mitochondrial genes associated with ROS (COX7B, NQO2) were dysregulated in T2D. Additionally, T1D alpha cells displayed altered expression of autoimmune-induced ER stress genes (ERLEC1, HSP90), whilst those from T2D subjects showed modified glycolytic and citrate cycle gene (LDHA?, PDHB, PDK4) expression. Thus, despite conserved alterations related to loss of function, alpha cells display disease-specific gene signatures which may be secondary to the main pathogenic events in each disease, namely immune- or metabolism-mediated-stress, in T1D and T2D, respectively.
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Affiliation(s)
- Emanuele Bosi
- Department of Experimental and Clinical Medicine, Pancreatic Islets Laboratory, University of Pisa, Pisa, Italy
- Department of Earth, Environmental and Life Sciences (DISTAV), University of Genoa, Genova, Italy
- Corresponding author
| | - Piero Marchetti
- Department of Experimental and Clinical Medicine, Pancreatic Islets Laboratory, University of Pisa, Pisa, Italy
| | - Guy Allen Rutter
- CR-CHUM and Université de Montréal, Montréal, QC, Canada
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Decio Laks Eizirik
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
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11
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Kang J, Yan Q, Zhou C, Zhou X, Tan Z. Replacing ZnSO 4 with Zn-glycine in the diet of goat promotes the pancreatic function of the offspring. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2022; 12:63-71. [PMID: 36514374 PMCID: PMC9731826 DOI: 10.1016/j.aninu.2022.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 06/20/2022] [Accepted: 08/12/2022] [Indexed: 12/16/2022]
Abstract
Zinc supplementation in the diet of goats affects pancreas development in offspring. However, the impact of maternal inorganic and organic zinc supplementation in offspring is poorly defined. In this study, 14 late-pregnant goats were assigned at random to the zinc sulfate group (ZnSO4, n = 7) and the zinc-glycine chelate group (Zn-Gly, n = 7), respectively. Serum samples and pancreas tissue were collected from kids whose mothers were fed ZnSO4 and Zn-Gly at the late pregnancy, respectively. Histologic examination showed no morphologic differences between the 2 groups. Pancreatic zinc content in kids tended to be increased when replacing ZnSO4 with Zn-Gly. The serum insulin concentration was greater and glucagon less in the Zn-Gly group when compared to the ZnSO4 group. The activities of lipase and chymotrypsin were enhanced when replacing ZnSO4 with Zn-Gly. Proteomics results showed that 234 proteins were differentially expressed between the 2 groups, some of which were associated with the secretion of insulin, enzyme activity and signal transduction. The results suggested that supply of dietary Zn-Gly to goats during late pregnancy promoted pancreatic function in offspring compared with dietary ZnSO4 supplementation. This provides new information about pancreatic function when supplementing different zinc sources in the diets of late pregnant goats.
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Affiliation(s)
- Jinhe Kang
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China
| | - Qiongxian Yan
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China
| | - Chuanshe Zhou
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China
| | - Xiaoling Zhou
- College of Animal Science, Tarim University, Alaer 843300, China
| | - Zhiliang Tan
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China
- Corresponding author.
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12
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Cheng Z, Qiao D, Zhao S, Zhang B, Lin Q, Xie F. Whole grain rice: Updated understanding of starch digestibility and the regulation of glucose and lipid metabolism. Compr Rev Food Sci Food Saf 2022; 21:3244-3273. [PMID: 35686475 DOI: 10.1111/1541-4337.12985] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 04/18/2022] [Accepted: 05/03/2022] [Indexed: 11/27/2022]
Abstract
Nowadays, resulting from disordered glucose and lipid metabolism, metabolic diseases (e.g., hyperglycemia, type 2 diabetes, and obesity) are among the most serious health issues facing humans worldwide. Increasing evidence has confirmed that dietary intervention (with healthy foods) is effective at regulating the metabolic syndrome. Whole grain rice (WGR) rich in dietary fiber and many bioactive compounds (e.g., γ-amino butyric acid, γ-oryzanol, and polyphenols) can not only inhibit starch digestion and prevent rapid increase in the blood glucose level, but also reduce oxidative stress and damage to the liver, thereby regulating glucose and lipid metabolism. The rate of starch digestion is directly related to the blood glucose level in the organism after WGR intake. Therefore, the effects of different factors (e.g., additives, cooking, germination, and physical treatments) on WGR starch digestibility are examined in this review. In addition, the mechanisms from human and animal experiments regarding the correlation between the intake of WGR or its products and the lowered blood glucose and lipid levels and the reduced incidence of diabetes and obesity are discussed. Moreover, information on developing WGR products with the health benefits is provided.
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Affiliation(s)
- Zihang Cheng
- Group for Cereals and Oils Processing, College of Food Science and Technology, Key Laboratory of Environment Correlative Dietology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Dongling Qiao
- Glyn O. Phillips Hydrocolloid Research Centre at HBUT, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, China
| | - Siming Zhao
- Group for Cereals and Oils Processing, College of Food Science and Technology, Key Laboratory of Environment Correlative Dietology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Binjia Zhang
- Group for Cereals and Oils Processing, College of Food Science and Technology, Key Laboratory of Environment Correlative Dietology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Qinlu Lin
- National Engineering Laboratory for Rice and By-product Deep Processing, Central South University of Forestry and Technology, Changsha, China
| | - Fengwei Xie
- School of Engineering, Newcastle University, Newcastle upon Tyne, UK
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13
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Rodgers RL. Glucagon, cyclic AMP, and hepatic glucose mobilization: A half‐century of uncertainty. Physiol Rep 2022; 10:e15263. [PMID: 35569125 PMCID: PMC9107925 DOI: 10.14814/phy2.15263] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 12/14/2022] Open
Abstract
For at least 50 years, the prevailing view has been that the adenylate cyclase (AC)/cyclic AMP (cAMP)/protein kinase A pathway is the predominant signal mediating the hepatic glucose‐mobilizing actions of glucagon. A wealth of evidence, however, supports the alternative, that the operative signal most of the time is the phospholipase C (PLC)/inositol‐phosphate (IP3)/calcium/calmodulin pathway. The evidence can be summarized as follows: (1) The consensus threshold glucagon concentration for activating AC ex vivo is 100 pM, but the statistical hepatic portal plasma glucagon concentration range, measured by RIA, is between 28 and 60 pM; (2) Within that physiological concentration range, glucagon stimulates the PLC/IP3 pathway and robustly increases glucose output without affecting the AC/cAMP pathway; (3) Activation of a latent, amplified AC/cAMP pathway at concentrations below 60 pM is very unlikely; and (4) Activation of the PLC/IP3 pathway at physiological concentrations produces intracellular effects that are similar to those produced by activation of the AC/cAMP pathway at concentrations above 100 pM, including elevated intracellular calcium and altered activities and expressions of key enzymes involved in glycogenolysis, gluconeogenesis, and glycogen synthesis. Under metabolically stressful conditions, as in the early neonate or exercising adult, plasma glucagon concentrations often exceed 100 pM, recruiting the AC/cAMP pathway and enhancing the activation of PLC/IP3 pathway to boost glucose output, adaptively meeting the elevated systemic glucose demand. Whether the AC/cAMP pathway is consistently activated in starvation or diabetes is not clear. Because the importance of glucagon in the pathogenesis of diabetes is becoming increasingly evident, it is even more urgent now to resolve lingering uncertainties and definitively establish glucagon’s true mechanism of glycemia regulation in health and disease.
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Affiliation(s)
- Robert L. Rodgers
- Department of Biomedical and Pharmaceutical Sciences College of Pharmacy University of Rhode Island Kingston Rhode Island USA
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14
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Karsai M, Zuellig RA, Lehmann R, Cuozzo F, Nasteska D, Luca E, Hantel C, Hodson DJ, Spinas GA, Rutter GA, Gerber PA. Lack of ZnT8 protects pancreatic islets from hypoxia- and cytokine-induced cell death. J Endocrinol 2022; 253:1-11. [PMID: 35017316 PMCID: PMC8859919 DOI: 10.1530/joe-21-0271] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/11/2022] [Indexed: 11/10/2022]
Abstract
Pancreatic β-cells depend on the well-balanced regulation of cytosolic zinc concentrations, providing sufficient zinc ions for the processing and storage of insulin, but avoiding toxic effects. The zinc transporter ZnT8, encoded by SLC30A8,is a key player regarding islet cell zinc homeostasis, and polymorphisms in this gene are associated with altered type 2 diabetes susceptibility in man. The objective of this study was to investigate the role of ZnT8 and zinc in situations of cellular stress as hypoxia or inflammation. Isolated islets of WT and global ZnT8-/- mice were exposed to hypoxia or cytokines and cell death was measured. To explore the role of changing intracellular Zn2+ concentrations, WT islets were exposed to different zinc concentrations using zinc chloride or the zinc chelator N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN). Hypoxia or cytokine (TNF-α, IFN-γ, IL1-β) treatment induced islet cell death, but to a lesser extent in islets from ZnT8-/- mice, which were shown to have a reduced zinc content. Similarly, chelation of zinc with TPEN reduced cell death in WT islets treated with hypoxia or cytokines, whereas increased zinc concentrations aggravated the effects of these stressors. This study demonstrates a reduced rate of cell death in islets from ZnT8-/- mice as compared to WT islets when exposed to two distinct cellular stressors, hypoxia or cytotoxic cytokines. This protection from cell death is, in part, mediated by a reduced zinc content in islet cells of ZnT8-/- mice. These findings may be relevant for altered diabetes burden in carriers of risk SLC30A8 alleles in man.
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Affiliation(s)
- Maria Karsai
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Richard A Zuellig
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Roger Lehmann
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Federica Cuozzo
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Daniela Nasteska
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Edlira Luca
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Constanze Hantel
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
- Medizinische Klinik und Poliklinik III, University Hospital Carl Gustav Carus Dresden, Dresden, Germany
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Giatgen A Spinas
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
- CR-CHUM, University of Montreal, Montreal, QC, Canada
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Philipp A Gerber
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
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15
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Andersen DB, Holst JJ. Peptides in the regulation of glucagon secretion. Peptides 2022; 148:170683. [PMID: 34748791 DOI: 10.1016/j.peptides.2021.170683] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/21/2021] [Accepted: 11/02/2021] [Indexed: 02/06/2023]
Abstract
Glucose homeostasis is maintained by the glucoregulatory hormones, glucagon, insulin and somatostatin, secreted from the islets of Langerhans. Glucagon is the body's most important anti-hypoglycemic hormone, mobilizing glucose from glycogen stores in the liver in response to fasting, thus maintaining plasma glucose levels within healthy limits. Glucagon secretion is regulated by both circulating nutrients, hormones and neuronal inputs. Hormones that may regulate glucagon secretion include locally produced insulin and somatostatin, but also urocortin-3, amylin and pancreatic polypeptide, and from outside the pancreas glucagon-like peptide-1 and 2, peptide tyrosine tyrosine and oxyntomodulin, glucose-dependent insulinotropic polypeptide, neurotensin and ghrelin, as well as the hypothalamic hormones arginine-vasopressin and oxytocin, and calcitonin from the thyroid. Each of these hormones have distinct effects, ranging from regulating blood glucose, to regulating appetite, stomach emptying rate and intestinal motility, which makes them interesting targets for treating metabolic diseases. Awareness regarding the potential effects of the hormones on glucagon secretion is important since secretory abnormalities could manifest as hyperglycemia or even lethal hypoglycemia. Here, we review the effects of each individual hormone on glucagon secretion, their interplay, and how treatments aimed at modulating the plasma levels of these hormones may also influence glucagon secretion and glycemic control.
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Affiliation(s)
- Daniel B Andersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200, Copenhagen N, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200, Copenhagen N, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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16
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Zibolka J, Bähr I, Peschke E, Mühlbauer E, Bazwinsky-Wutschke I. Human and Rodent Cell Lines as Models of Functional Melatonin-Responsive Pancreatic Islet Cells. Methods Mol Biol 2022; 2550:329-352. [PMID: 36180704 DOI: 10.1007/978-1-0716-2593-4_35] [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] [Indexed: 06/16/2023]
Abstract
Cell culture of different pancreatic islet cell lines, like the murine α-cell line αTC1.9, the rat β-cell lines INS-1 and INS-1 832/13, and the human δ-cell line QGP-1, can serve as valuable cell models for the analysis of melatonin-dependent modulation of hormone secretion. The paper summarizes in detail the requirements of culture for each cell line and includes batch protocols to stimulate hormone secretion and to treat cells with several melatonin concentrations as previously published. We here describe the processing of collected cell pellets or cell culture supernatants as well as different methods to analyze cell experiments after melatonin treatment on the basis of our own experience. Finally, we outlined for each cell line under which conditions the melatonin treatment should be performed to gain reproducible results.
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Affiliation(s)
- Juliane Zibolka
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Ina Bähr
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Elmar Peschke
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Eckhard Mühlbauer
- Saxon Academy of Sciences and Humanities in Leipzig, Leipzig, Germany
| | - Ivonne Bazwinsky-Wutschke
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
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17
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Vitamin D Deficiency Is Inversely Associated with Homeostatic Model Assessment of Insulin Resistance. Nutrients 2021; 13:nu13124358. [PMID: 34959910 PMCID: PMC8705502 DOI: 10.3390/nu13124358] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 01/08/2023] Open
Abstract
The study was conducted to comprehensively assess the association of the concentration of vitamin D in the blood and insulin resistance in non-diabetic subjects. The objective was to pool the results from all observational studies from the beginning of 1980 to August 2021. PubMed, Medline and Embase were systematically searched for the observational studies. Filters were used for more focused results. A total of 2248 articles were found after raw search which were narrowed down to 32 articles by the systematic selection of related articles. Homeostatic Model Assessment of Insulin Resistance (HOMAIR) was used as the measure of insulin resistance and correlation coefficient was used as a measure of the relationship between vitamin D levels and the insulin resistance. Risk of bias tables and summary plots were built using Revman software version 5.3 while Comprehensive meta-analysis version 3 was used for the construction of forest plot. The results showed an inverse association between the status of vitamin D and insulin resistance (r = -0.217; 95% CI = -0.161 to -0.272; p = 0.000). A supplement of vitamin D can help reduce the risk of insulin resistance; however further studies, like randomized controlled trials are needed to confirm the results.
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18
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Asadi F, Dhanvantari S. Pathways of Glucagon Secretion and Trafficking in the Pancreatic Alpha Cell: Novel Pathways, Proteins, and Targets for Hyperglucagonemia. Front Endocrinol (Lausanne) 2021; 12:726368. [PMID: 34659118 PMCID: PMC8511682 DOI: 10.3389/fendo.2021.726368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/13/2021] [Indexed: 12/15/2022] Open
Abstract
Patients with diabetes mellitus exhibit hyperglucagonemia, or excess glucagon secretion, which may be the underlying cause of the hyperglycemia of diabetes. Defective alpha cell secretory responses to glucose and paracrine effectors in both Type 1 and Type 2 diabetes may drive the development of hyperglucagonemia. Therefore, uncovering the mechanisms that regulate glucagon secretion from the pancreatic alpha cell is critical for developing improved treatments for diabetes. In this review, we focus on aspects of alpha cell biology for possible mechanisms for alpha cell dysfunction in diabetes: proglucagon processing, intrinsic and paracrine control of glucagon secretion, secretory granule dynamics, and alterations in intracellular trafficking. We explore possible clues gleaned from these studies in how inhibition of glucagon secretion can be targeted as a treatment for diabetes mellitus.
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Affiliation(s)
- Farzad Asadi
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
| | - Savita Dhanvantari
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
- Imaging Research Program, Lawson Health Research Institute, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
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19
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Kahn SE, Mather KJ, Arslanian SA, Barengolts E, Buchanan TA, Caprio S, Ehrmann DA, Hannon TS, Marcovina S, Nadeau KJ, Utzschneider KM, Xiang AH, Edelstein SL. Hyperglucagonemia Does Not Explain the β-Cell Hyperresponsiveness and Insulin Resistance in Dysglycemic Youth Compared With Adults: Lessons From the RISE Study. Diabetes Care 2021; 44:1961-1969. [PMID: 34131047 PMCID: PMC8740916 DOI: 10.2337/dc21-0460] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/23/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine whether β-cell hyperresponsiveness and insulin resistance in youth versus adults in the Restoring Insulin Secretion (RISE) Study are related to increased glucagon release. RESEARCH DESIGN AND METHODS In 66 youth and 350 adults with impaired glucose tolerance (IGT) or recently diagnosed type 2 diabetes (drug naive), we performed hyperglycemic clamps and oral glucose tolerance tests (OGTTs). From clamps we quantified insulin sensitivity (M/I), plasma fasting glucagon and C-peptide, steady-state glucagon and C-peptide at glucose of 11.1 mmol/L, and arginine-stimulated glucagon (acute glucagon response [AGR]) and C-peptide (ACPRmax) responses at glucose >25 mmol/L. RESULTS Mean ± SD fasting glucagon (7.63 ± 3.47 vs. 8.55 ± 4.47 pmol/L; P = 0.063) and steady-state glucagon (2.24 ± 1.46 vs. 2.49 ± 1.96 pmol/L, P = 0.234) were not different in youth and adults, respectively, while AGR was lower in youth (14.1 ± 5.2 vs. 16.8 ± 8.8 pmol/L, P = 0.001). Significant age-group differences in insulin sensitivity, fasting C-peptide, steady-state C-peptide, and ACPRmax were not related to glucagon. Fasting glucose and glucagon were positively correlated in adults (r = 0.133, P = 0.012) and negatively correlated in youth (r = -0.143, P = 0.251). In both age-groups, higher fasting glucagon was associated with higher fasting C-peptide (youth r = 0.209, P = 0.091; adults r = 0.335, P < 0.001) and lower insulin sensitivity (youth r = -0.228, P = 0.066; adults r = -0.324, P < 0.001). With comparable fasting glucagon, youth had greater C-peptide and lower insulin sensitivity. OGTT suppression of glucagon was greater in youth. CONCLUSIONS Youth with IGT or recently diagnosed type 2 diabetes (drug naive) have hyperresponsive β-cells and lower insulin sensitivity, but their glucagon concentrations are not increased compared with those in adults. Thus, α-cell dysfunction does not appear to explain the difference in β-cell function and insulin sensitivity in youth versus adults.
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Affiliation(s)
- Steven E Kahn
- VA Puget Sound Health Care System, Seattle, WA.,University of Washington, Seattle, WA
| | | | | | | | - Thomas A Buchanan
- Keck School of Medicine of University of Southern California, Los Angeles, CA
| | | | | | | | | | | | | | - Anny H Xiang
- Kaiser Permanente Southern California, Pasadena, CA
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20
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Kahn SE, Edelstein SL, Arslanian SA, Barengolts E, Caprio S, Ehrmann DA, Hannon TS, Marcovina S, Mather KJ, Nadeau KJ, Utzschneider KM, Xiang AH, Buchanan TA. Effect of Medical and Surgical Interventions on α-Cell Function in Dysglycemic Youth and Adults in the RISE Study. Diabetes Care 2021; 44:1948-1960. [PMID: 34135015 PMCID: PMC8740921 DOI: 10.2337/dc21-0461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/21/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To compare effects of medications and laparoscopic gastric band surgery (LB) on α-cell function in dysglycemic youth and adults in the Restoring Insulin Secretion (RISE) Study protocols. RESEARCH DESIGN AND METHODS Glucagon was measured in three randomized, parallel, clinical studies: 1) 91 youth studied at baseline, after 12 months on metformin alone (MET) or glargine followed by metformin (G/M), and 3 months after treatment withdrawal; 2) 267 adults studied at the same time points and treated with MET, G/M, or liraglutide plus metformin (L+M) or given placebo (PLAC); and 3) 88 adults studied at baseline and after 12 and 24 months of LB or MET. Fasting glucagon, glucagon suppression by glucose, and acute glucagon response (AGR) to arginine were assessed during hyperglycemic clamps. Glucagon suppression was also measured during oral glucose tolerance tests (OGTTs). RESULTS No change in fasting glucagon, steady-state glucagon, or AGR was seen at 12 months following treatment with MET or G/M (in youth and adults) or PLAC (in adults). In contrast, L+M reduced these measures at 12 months (all P ≤ 0.005), which was maintained 3 months after treatment withdrawal (all P < 0.01). LB in adults also reduced fasting glucagon, steady-state glucagon, and AGR at 12 and 24 months (P < 0.05 for all, except AGR at 12 months [P = 0.098]). Similarly, glucagon suppression during OGTTs was greater with L+M and LB. Linear models demonstrated that treatment effects on glucagon with L+M and LB were largely associated with weight loss. CONCLUSIONS Glucagon concentrations were reduced by L+M and LB in adults with dysglycemia, an effect principally attributable to weight loss in both interventions.
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Affiliation(s)
- Steven E Kahn
- VA Puget Sound Health Care System, Seattle, WA.,University of Washington, Seattle, WA
| | | | | | | | | | | | | | | | | | | | | | - Anny H Xiang
- Kaiser Permanente Southern California, Pasadena, CA
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21
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Acreman S, Zhang Q. Regulation of α-cell glucagon secretion: The role of second messengers. Chronic Dis Transl Med 2021; 8:7-18. [PMID: 35620162 PMCID: PMC9128566 DOI: 10.1016/j.cdtm.2021.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/15/2021] [Indexed: 11/30/2022] Open
Abstract
Glucagon is a potent glucose‐elevating hormone that is secreted by pancreatic α‐cells. While well‐controlled glucagon secretion plays an important role in maintaining systemic glucose homeostasis and preventing hypoglycaemia, it is increasingly apparent that defects in the regulation of glucagon secretion contribute to impaired counter‐regulation and hyperglycaemia in diabetes. It has therefore been proposed that pharmacological interventions targeting glucagon secretion/signalling can have great potential in improving glycaemic control of patients with diabetes. However, despite decades of research, a consensus on the precise mechanisms of glucose regulation of glucagon secretion is yet to be reached. Second messengers are a group of small intracellular molecules that relay extracellular signals to the intracellular signalling cascade, modulating cellular functions. There is a growing body of evidence that second messengers, such as cAMP and Ca2+, play critical roles in α‐cell glucose‐sensing and glucagon secretion. In this review, we discuss the impact of second messengers on α‐cell electrical activity, intracellular Ca2+ dynamics and cell exocytosis. We highlight the possibility that the interaction between different second messengers may play a key role in the glucose‐regulation of glucagon secretion.
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22
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Pancreatic β Cells Inhibit Glucagon Secretion from α Cells: An In Vitro Demonstration of α-β Cell Interaction. Nutrients 2021; 13:nu13072281. [PMID: 34209449 PMCID: PMC8308288 DOI: 10.3390/nu13072281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 06/25/2021] [Accepted: 06/27/2021] [Indexed: 12/24/2022] Open
Abstract
Interactions between endocrine α and β cells are critical to their secretory function in vivo. The interactions are highly regulated, although yet to be fully understood. In this study, we aim to assess the impact of α and β cell co-culture on hormone secretion. Mouse clonal cell lines α-TC6-1 (α cell line) and MIN-6 (β cell line) were cultured independently or in combination in a medium containing 5.5, 11.1, or 25 mM glucose, respectively. After 72 h, hormone release was measured using insulin and glucagon secretion assays, the cell distribution was visualized by inverted microscopy and an immunocytochemistry assay, and changes in gene expressions were assessed using the RT-PCR technique. The co-culture of the two cell lines caused a decrease in glucagon secretion from α-TC1-6 cells, while no effect on insulin secretion from MIN-6 cells was revealed. Both types of cells were randomly scattered throughout the culture flask, unlike in mice islets in vivo where β cells cluster in the core and α cells are localized at the periphery. During the α-β cell co-culture, the gene expression of glucagon (Gcg) decreased significantly. We conclude that islet β cells suppress glucagon secretion from α cells, apparently via direct cell-to-cell contact, of which the molecular mechanism needs further verification.
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Ng XW, Chung YH, Piston DW. Intercellular Communication in the Islet of Langerhans in Health and Disease. Compr Physiol 2021; 11:2191-2225. [PMID: 34190340 DOI: 10.1002/cphy.c200026] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Blood glucose homeostasis requires proper function of pancreatic islets, which secrete insulin, glucagon, and somatostatin from the β-, α-, and δ-cells, respectively. Each islet cell type is equipped with intrinsic mechanisms for glucose sensing and secretory actions, but these intrinsic mechanisms alone cannot explain the observed secretory profiles from intact islets. Regulation of secretion involves interconnected mechanisms among and between islet cell types. Islet cells lose their normal functional signatures and secretory behaviors upon dispersal as compared to intact islets and in vivo. In dispersed islet cells, the glucose response of insulin secretion is attenuated from that seen from whole islets, coordinated oscillations in membrane potential and intracellular Ca2+ activity, as well as the two-phase insulin secretion profile, are missing, and glucagon secretion displays higher basal secretion profile and a reverse glucose-dependent response from that of intact islets. These observations highlight the critical roles of intercellular communication within the pancreatic islet, and how these communication pathways are crucial for proper hormonal and nonhormonal secretion and glucose homeostasis. Further, misregulated secretions of islet secretory products that arise from defective intercellular islet communication are implicated in diabetes. Intercellular communication within the islet environment comprises multiple mechanisms, including electrical synapses from gap junctional coupling, paracrine interactions among neighboring cells, and direct cell-to-cell contacts in the form of juxtacrine signaling. In this article, we describe the various mechanisms that contribute to proper islet function for each islet cell type and how intercellular islet communications are coordinated among the same and different islet cell types. © 2021 American Physiological Society. Compr Physiol 11:2191-2225, 2021.
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Affiliation(s)
- Xue W Ng
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - Yong H Chung
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
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Rafiq S, Jeppesen PB. Insulin Resistance Is Inversely Associated with the Status of Vitamin D in Both Diabetic and Non-Diabetic Populations. Nutrients 2021; 13:1742. [PMID: 34063822 PMCID: PMC8224049 DOI: 10.3390/nu13061742] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 02/06/2023] Open
Abstract
Vitamin D has been implicated in the regulation of glucose metabolism and insulin resistance. We designed this study to provide evidence that insulin resistance is dependent on the concentration of vitamin D in the body. Forty observational studies of both type 2 diabetes mellitus patients and healthy subjects were included in this meta-analysis. Related articles were searched from Embase, PubMed, and Medline through January 2021. Filters for search were used to obtain more focused results. We used Comprehensive Meta-Analysis Version 3 for the construction of forest plots. RevMan software version 5.3 was used to build the risk of bias tables and summary plots. The observational studies included in this systematic review and meta-analysis showed an inverse relationship of insulin resistance with the status of vitamin D both in non-diabetic (r = -0.188; 95% CI = -0.141 to -0.234; p = 0.000) and diabetic (r = -0.255; 95% CI = -0.392 to -0.107, p = 0.001) populations. From the meta-analysis we concluded that hypovitaminosis D is related to increased levels of insulin resistance in both type 2 diabetes patients and the healthy population all over the world.
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Affiliation(s)
- Shamaila Rafiq
- Department of Clinical Medicine, Aarhus University, Aarhus N, 8200 Aarhus, Denmark;
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Kjeldsen SAS, Hansen LH, Esser N, Mongovin S, Winther-Sørensen M, Galsgaard KD, Hunt JE, Kissow H, Ceutz FR, Terzic D, Mark PD, Plomgaard P, Goetze JP, Goossens GH, Blaak EE, Deacon CF, Rosenkilde MM, Zraika S, Holst JJ, Wewer Albrechtsen NJ. Neprilysin Inhibition Increases Glucagon Levels in Humans and Mice With Potential Effects on Amino Acid Metabolism. J Endocr Soc 2021; 5:bvab084. [PMID: 34337276 PMCID: PMC8317634 DOI: 10.1210/jendso/bvab084] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Indexed: 01/12/2023] Open
Abstract
Context Inhibitors of the protease neprilysin (NEP) are used for treating heart failure, but are also linked to improvements in metabolism. NEP may cleave proglucagon-derived peptides, including the glucose and amino acid (AA)-regulating hormone glucagon. Studies investigating NEP inhibition on glucagon metabolism are warranted. Objective This work aims to investigate whether NEP inhibition increases glucagon levels. Methods Plasma concentrations of glucagon and AAs were measured in eight healthy men during a mixed meal with and without a single dose of the NEP inhibitor/angiotensin II type 1 receptor antagonist, sacubitril/valsartan (194 mg/206 mg). Long-term effects of sacubitril/valsartan (8 weeks) were investigated in individuals with obesity (n = 7). Mass spectrometry was used to investigate NEP-induced glucagon degradation, and the derived glucagon fragments were tested pharmacologically in cells transfected with the glucagon receptor (GCGR). Genetic deletion or pharmacological inhibition of NEP with or without concomitant GCGR antagonism was tested in mice to evaluate effects on AA metabolism. Results In healthy men, a single dose of sacubitril/valsartan significantly increased postprandial concentrations of glucagon by 228%, concomitantly lowering concentrations of AAs including glucagonotropic AAs. Eight-week sacubitril/valsartan treatment increased fasting glucagon concentrations in individuals with obesity. NEP cleaved glucagon into 5 inactive fragments (in vitro). Pharmacological NEP inhibition protected both exogenous and endogenous glucagon in mice after an AA challenge, while NEP-deficient mice showed elevated fasting and AA-stimulated plasma concentrations of glucagon and urea compared to controls. Conclusion NEP cleaves glucagon, and inhibitors of NEP result in hyperglucagonemia and may increase postprandial AA catabolism without affecting glycemia.
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Affiliation(s)
- Sasha A S Kjeldsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Lasse H Hansen
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark.,Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Nathalie Esser
- Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington 98195-6426, USA.,Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
| | - Steve Mongovin
- Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jenna E Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Hannelouise Kissow
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Frederik R Ceutz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Dijana Terzic
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Peter D Mark
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Peter Plomgaard
- Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jens P Goetze
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Gijs H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Ellen E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Carolyn F Deacon
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark
| | - Mette M Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Sakeneh Zraika
- Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington 98195-6426, USA.,Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen,Denmark.,Department of Clinical Biochemistry, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
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Zeigerer A, Sekar R, Kleinert M, Nason S, Habegger KM, Müller TD. Glucagon's Metabolic Action in Health and Disease. Compr Physiol 2021; 11:1759-1783. [PMID: 33792899 PMCID: PMC8513137 DOI: 10.1002/cphy.c200013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Discovered almost simultaneously with insulin, glucagon is a pleiotropic hormone with metabolic action that goes far beyond its classical role to increase blood glucose. Albeit best known for its ability to directly act on the liver to increase de novo glucose production and to inhibit glycogen breakdown, glucagon lowers body weight by decreasing food intake and by increasing metabolic rate. Glucagon further promotes lipolysis and lipid oxidation and has positive chronotropic and inotropic effects in the heart. Interestingly, recent decades have witnessed a remarkable renaissance of glucagon's biology with the acknowledgment that glucagon has pharmacological value beyond its classical use as rescue medication to treat severe hypoglycemia. In this article, we summarize the multifaceted nature of glucagon with a special focus on its hepatic action and discuss the pharmacological potential of either agonizing or antagonizing the glucagon receptor for health and disease. © 2021 American Physiological Society. Compr Physiol 11:1759-1783, 2021.
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Affiliation(s)
- Anja Zeigerer
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Revathi Sekar
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Maximilian Kleinert
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Shelly Nason
- Comprehensive Diabetes Center, Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kirk M. Habegger
- Comprehensive Diabetes Center, Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Timo D. Müller
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
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Barragán-Álvarez CP, Padilla-Camberos E, Díaz NF, Cota-Coronado A, Hernández-Jiménez C, Bravo-Reyna CC, Díaz-Martínez NE. Loss of Znt8 function in diabetes mellitus: risk or benefit? Mol Cell Biochem 2021; 476:2703-2718. [PMID: 33666829 DOI: 10.1007/s11010-021-04114-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
The zinc transporter 8 (ZnT8) plays an essential role in zinc homeostasis inside pancreatic β cells, its function is related to the stabilization of insulin hexameric form. Genome-wide association studies (GWAS) have established a positive and negative relationship of ZnT8 variants with type 2 diabetes mellitus (T2DM), exposing a dual and controversial role. The first hypotheses about its role in T2DM indicated a higher risk of developing T2DM for loss of function; nevertheless, recent GWAS of ZnT8 loss-of-function mutations in humans have shown protection against T2DM. With regard to the ZnT8 role in T2DM, most studies have focused on rodent models and common high-risk variants; however, considerable differences between human and rodent models have been found and the new approaches have included lower-frequency variants as a tool to clarify gene functions, allowing a better understanding of the disease and offering possible therapeutic targets. Therefore, this review will discuss the physiological effects of the ZnT8 variants associated with a major and lower risk of T2DM, emphasizing the low- and rare-frequency variants.
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Affiliation(s)
- Carla P Barragán-Álvarez
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Eduardo Padilla-Camberos
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Nestor F Díaz
- Departamento de Fisiología y Desarrollo Celular, Instituto Nacional de Perinatología, Mexico City, Mexico
| | - Agustín Cota-Coronado
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Claudia Hernández-Jiménez
- Departamento de Cirugía Experimental, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Carlos C Bravo-Reyna
- Departamento de Cirugía Experimental, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Nestor E Díaz-Martínez
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico.
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Clavijo Jordan V, Hines CDG, Gantert LT, Wang S, Conarello S, Preihs C, Chirayil S, Klimas M, Evelhoch JL, Sherry AD. Imaging Beta-Cell Function in the Pancreas of Non-Human Primates Using a Zinc-Sensitive MRI Contrast Agent. Front Endocrinol (Lausanne) 2021; 12:641722. [PMID: 34122330 PMCID: PMC8187943 DOI: 10.3389/fendo.2021.641722] [Citation(s) in RCA: 2] [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] [Received: 12/14/2020] [Accepted: 04/26/2021] [Indexed: 12/03/2022] Open
Abstract
Non-invasive beta cell function measurements may provide valuable information for improving diabetes diagnostics and disease management as the integrity and function of pancreatic beta cells have been found to be compromised in Type-1 and Type-2 diabetes. Currently, available diabetes assays either lack functional information or spatial identification of beta cells. In this work, we introduce a method to assess the function of beta cells in the non-human primate pancreas non-invasively with MRI using a Gd-based zinc(II) sensor as a contrast agent, Gd-CP027. Additionally, we highlight the role of zinc(II) ions in the paracrine signaling of the endocrine pancreas via serological measurements of insulin and c-peptide. Non-human primates underwent MRI exams with simultaneous blood sampling during a Graded Glucose Infusion (GGI) with Gd-CP027 or with a non-zinc(II) sensitive contrast agent, gadofosveset. Contrast enhancement of the pancreas resulting from co-release of zinc(II) ion with insulin was observed focally when using the zinc(II)-specific agent, Gd-CP027, whereas little enhancement was detected when using gadofosveset. The contrast enhancement detected by Gd-CP027 increased in parallel with an increased dose of infused glucose. Serological measurements of C-peptide and insulin indicate that Gd-CP027, a high affinity zinc(II) contrast agent, potentiates their secretion only as a function of glucose stimulation. Taken in concert, this assay offers the possibility of detecting beta cell function in vivo non-invasively with MRI and underscores the role of zinc(II) in endocrine glucose metabolism.
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Affiliation(s)
- Veronica Clavijo Jordan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | | | - Liza T. Gantert
- Translational Biomarkers, Merck & Co., Inc., Kenilworth, NJ, United States
| | - Shubing Wang
- Biometrics Research, Merck & Co., Inc., Kenilworth, NJ, United States
| | | | - Christian Preihs
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- VitalQuan, LLC, Dallas, TX, United States
| | - Sara Chirayil
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Michael Klimas
- Translational Biomarkers, Merck & Co., Inc., Kenilworth, NJ, United States
| | | | - A. Dean Sherry
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- VitalQuan, LLC, Dallas, TX, United States
- Department of Radiology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Chemistry & Biochemistry, The University of Texas at Dallas, Richardson, TX, United States
- *Correspondence: A. Dean Sherry,
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Neumaier F, Schneider T, Albanna W. Ca v2.3 channel function and Zn 2+-induced modulation: potential mechanisms and (patho)physiological relevance. Channels (Austin) 2020; 14:362-379. [PMID: 33079629 PMCID: PMC7583514 DOI: 10.1080/19336950.2020.1829842] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Voltage-gated calcium channels (VGCCs) are critical for Ca2+ influx into all types of excitable cells, but their exact function is still poorly understood. Recent reconstruction of homology models for all human VGCCs at atomic resolution provides the opportunity for a structure-based discussion of VGCC function and novel insights into the mechanisms underlying Ca2+ selective flux through these channels. In the present review, we use these data as a basis to examine the structure, function, and Zn2+-induced modulation of Cav2.3 VGCCs, which mediate native R-type currents and belong to the most enigmatic members of the family. Their unique sensitivity to Zn2+ and the existence of multiple mechanisms of Zn2+ action strongly argue for a role of these channels in the modulatory action of endogenous loosely bound Zn2+, pools of which have been detected in a number of neuronal, endocrine, and reproductive tissues. Following a description of the different mechanisms by which Zn2+ has been shown or is thought to alter the function of these channels, we discuss their potential (patho)physiological relevance, taking into account what is known about the magnitude and function of extracellular Zn2+ signals in different tissues. While still far from complete, the picture that emerges is one where Cav2.3 channel expression parallels the occurrence of loosely bound Zn2+ pools in different tissues and where these channels may serve to translate physiological Zn2+ signals into changes of electrical activity and/or intracellular Ca2+ levels.
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Affiliation(s)
- Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5) , Jülich, Germany.,University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging , Cologne, Germany
| | - Toni Schneider
- Institute of Neurophysiology , Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Walid Albanna
- Department of Neurosurgery, RWTH Aachen University , Aachen, Germany
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30
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Huey J, Keutler K, Schultz C. Chemical Biology Toolbox for Studying Pancreatic Islet Function - A Perspective. Cell Chem Biol 2020; 27:1015-1031. [PMID: 32822616 DOI: 10.1016/j.chembiol.2020.07.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/10/2020] [Accepted: 07/28/2020] [Indexed: 01/14/2023]
Abstract
The islets of Langerhans represent one of the many complex endocrine organs in mammals. Traditionally, islet function is studied by a mixture of physiological, cell biological, and molecular biological methods. Recently, novel techniques stemming from the ever-increasing toolbox provided by chemical laboratories have been added to the repertoire. Many emerging techniques will soon be available to manipulate and monitor islet function at the single-cell level and potentially in intact model animals, as well as in isolated human islets. Here, we review the most current small-molecule-based and genetically encoded molecular tool sets available to study islet function. We provide an outlook regarding future tool developments that will impact islet research, with a special focus on the interplay between different islet cell types.
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Affiliation(s)
- Julia Huey
- Program in Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97210, USA; Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA
| | - Kaya Keutler
- Program in Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97210, USA; Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA
| | - Carsten Schultz
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA.
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The RNA-binding protein, HuD regulates proglucagon biosynthesis in pancreatic α cells. Biochem Biophys Res Commun 2020; 530:266-272. [PMID: 32828297 DOI: 10.1016/j.bbrc.2020.07.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 12/28/2022]
Abstract
Glucagon is a peptide hormone generated by pancreatic α cells. It is the counterpart of insulin and plays an essential role in the regulation of blood glucose level. Therefore, a tight regulation of glucagon levels is pivotal to maintain homeostasis of blood glucose. However, little is known about the mechanisms regulating glucagon biosynthesis. In this study, we demonstrate that the RNA-binding protein HuD regulates glucagon expression in pancreatic α cells. HuD was found in α cells from mouse pancreatic islet and mouse glucagonoma αTC1 cell line. Ribonucleoprotein immunoprecipitation analysis, followed by RT-qPCR showed the association of HuD with glucagon mRNA. Knockdown of HuD resulted in a reduction in both proglucagon expression and cellular glucagon level by decreasing its de novo synthesis. Reporter analysis using the EGFP reporter containing 3' untranslated region (3'UTR) of glucagon mRNA showed that HuD regulates proglucagon expression via its 3'UTR. In addition, the relative level of glucagon in the islets and plasma was lower in HuD knockout (KO) mice compared to age-matched control mice. Taken together, these results suggest that HuD is a novel factor regulating the biosynthesis of proglucagon in pancreatic α cells.
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32
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Zaborska KE, Dadi PK, Dickerson MT, Nakhe AY, Thorson AS, Schaub CM, Graff SM, Stanley JE, Kondapavuluru RS, Denton JS, Jacobson DA. Lactate activation of α-cell K ATP channels inhibits glucagon secretion by hyperpolarizing the membrane potential and reducing Ca 2+ entry. Mol Metab 2020; 42:101056. [PMID: 32736089 PMCID: PMC7479281 DOI: 10.1016/j.molmet.2020.101056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/17/2020] [Accepted: 07/24/2020] [Indexed: 12/20/2022] Open
Abstract
Objective Elevations in pancreatic α-cell intracellular Ca2+ ([Ca2+]i) lead to glucagon (GCG) secretion. Although glucose inhibits GCG secretion, how lactate and pyruvate control α-cell Ca2+ handling is unknown. Lactate enters cells through monocarboxylate transporters (MCTs) and is also produced during glycolysis by lactate dehydrogenase A (LDHA), an enzyme expressed in α-cells. As lactate activates ATP-sensitive K+ (KATP) channels in cardiomyocytes, lactate may also modulate α-cell KATP. Therefore, this study investigated how lactate signaling controls α-cell Ca2+ handling and GCG secretion. Methods Mouse and human islets were used in combination with confocal microscopy, electrophysiology, GCG immunoassays, and fluorescent thallium flux assays to assess α-cell Ca2+ handling, Vm, KATP currents, and GCG secretion. Results Lactate-inhibited mouse (75 ± 25%) and human (47 ± 9%) α-cell [Ca2+]i fluctuations only under low-glucose conditions (1 mM) but had no effect on β- or δ-cells [Ca2+]i. Glyburide inhibition of KATP channels restored α-cell [Ca2+]i fluctuations in the presence of lactate. Lactate transport into α-cells via MCTs hyperpolarized mouse (14 ± 1 mV) and human (12 ± 1 mV) α-cell Vm and activated KATP channels. Interestingly, pyruvate showed a similar KATP activation profile and α-cell [Ca2+]i inhibition as lactate. Lactate-induced inhibition of α-cell [Ca2+]i influx resulted in reduced GCG secretion in mouse (62 ± 6%) and human (43 ± 13%) islets. Conclusions These data demonstrate for the first time that lactate entry into α-cells through MCTs results in KATP activation, Vm hyperpolarization, reduced [Ca2+]i, and inhibition of GCG secretion. Thus, taken together, these data indicate that lactate either within α-cells and/or elevated in serum could serve as important modulators of α-cell function. Lactate reduces islet α-cell Ca2+ entry under low glucose conditions. Lactate does not alter β- or δ-cell Ca2+ handling under low glucose conditions. Lactate enters islet α-cells through monocarboxylate transporters. Lactate hyperpolarizes islet α-cell membrane potential by activating KATP channels. Lactate reduces mouse and human islet glucagon secretion.
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Affiliation(s)
- Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jade E Stanley
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Roy S Kondapavuluru
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jerod S Denton
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Omar-Hmeadi M, Lund PE, Gandasi NR, Tengholm A, Barg S. Paracrine control of α-cell glucagon exocytosis is compromised in human type-2 diabetes. Nat Commun 2020; 11:1896. [PMID: 32312960 PMCID: PMC7171169 DOI: 10.1038/s41467-020-15717-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 03/23/2020] [Indexed: 01/05/2023] Open
Abstract
Glucagon is released from pancreatic α-cells to activate pathways that raise blood glucose. Its secretion is regulated by α-cell-intrinsic glucose sensing and paracrine control through insulin and somatostatin. To understand the inadequately high glucagon levels that contribute to hyperglycemia in type-2 diabetes (T2D), we analyzed granule behavior, exocytosis and membrane excitability in α-cells of 68 non-diabetic and 21 T2D human donors. We report that exocytosis is moderately reduced in α-cells of T2D donors, without changes in voltage-dependent ion currents or granule trafficking. Dispersed α-cells have a non-physiological V-shaped dose response to glucose, with maximal exocytosis at hyperglycemia. Within intact islets, hyperglycemia instead inhibits α-cell exocytosis, but not in T2D or when paracrine inhibition by insulin or somatostatin is blocked. Surface expression of somatostatin-receptor-2 is reduced in T2D, suggesting a mechanism for the observed somatostatin resistance. Thus, elevated glucagon in human T2D may reflect α-cell insensitivity to paracrine inhibition at hyperglycemia. Glucagon is elevated Type-2 diabetes, which contributes to poor glucose control in patients with the disease. Here the authors report that secretion of the hormone is controlled by paracrine inhibition, and that resistance of α-cells to somatostatin can explain hyperglucagonemia in type-2 diabetes.
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Affiliation(s)
- Muhmmad Omar-Hmeadi
- Medical Cell Biology, Uppsala University, Box 571, BMC, 751 23, Uppsala, Sweden
| | - Per-Eric Lund
- Medical Cell Biology, Uppsala University, Box 571, BMC, 751 23, Uppsala, Sweden
| | - Nikhil R Gandasi
- Medical Cell Biology, Uppsala University, Box 571, BMC, 751 23, Uppsala, Sweden
| | - Anders Tengholm
- Medical Cell Biology, Uppsala University, Box 571, BMC, 751 23, Uppsala, Sweden
| | - Sebastian Barg
- Medical Cell Biology, Uppsala University, Box 571, BMC, 751 23, Uppsala, Sweden.
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Davis EM, Sandoval DA. Glucagon‐Like Peptide‐1: Actions and Influence on Pancreatic Hormone Function. Compr Physiol 2020; 10:577-595. [DOI: 10.1002/cphy.c190025] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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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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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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Grubelnik V, Markovič R, Lipovšek S, Leitinger G, Gosak M, Dolenšek J, Valladolid-Acebes I, Berggren PO, Stožer A, Perc M, Marhl M. Modelling of dysregulated glucagon secretion in type 2 diabetes by considering mitochondrial alterations in pancreatic α-cells. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191171. [PMID: 32218947 PMCID: PMC7029933 DOI: 10.1098/rsos.191171] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 12/16/2019] [Indexed: 05/15/2023]
Abstract
Type 2 diabetes mellitus (T2DM) has been associated with insulin resistance and the failure of β-cells to produce and secrete enough insulin as the disease progresses. However, clinical treatments based solely on insulin secretion and action have had limited success. The focus is therefore shifting towards α-cells, in particular to the dysregulated secretion of glucagon. Our qualitative electron-microscopy-based observations gave an indication that mitochondria in α-cells are altered in Western-diet-induced T2DM. In particular, α-cells extracted from mouse pancreatic tissue showed a lower density of mitochondria, a less expressed matrix and a lower number of cristae. These deformities in mitochondrial ultrastructure imply a decreased efficiency in mitochondrial ATP production, which prompted us to theoretically explore and clarify one of the most challenging problems associated with T2DM, namely the lack of glucagon secretion in hypoglycaemia and its oversecretion at high blood glucose concentrations. To this purpose, we constructed a novel computational model that links α-cell metabolism with their electrical activity and glucagon secretion. Our results show that defective mitochondrial metabolism in α-cells can account for dysregulated glucagon secretion in T2DM, thus improving our understanding of T2DM pathophysiology and indicating possibilities for new clinical treatments.
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Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
| | - Saška Lipovšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000 Maribor, Slovenia
- Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Gerd Leitinger
- Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Ismael Valladolid-Acebes
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, 171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, 171 76 Stockholm, Sweden
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Matjaž Perc
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Complexity Science Hub Vienna, 1080 Vienna, Austria
- Authors for correspondence: Matjač Perc e-mail:
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Education, University of Maribor, 2000 Maribor, Slovenia
- Authors for correspondence: Marko Marhl e-mail:
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Grubelnik V, Markovič R, Lipovšek S, Leitinger G, Gosak M, Dolenšek J, Valladolid-Acebes I, Berggren PO, Stožer A, Perc M, Marhl M. Modelling of dysregulated glucagon secretion in type 2 diabetes by considering mitochondrial alterations in pancreatic α-cells. ROYAL SOCIETY OPEN SCIENCE 2020. [PMID: 32218947 DOI: 10.5061/dryad.9n2k1vk] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Type 2 diabetes mellitus (T2DM) has been associated with insulin resistance and the failure of β-cells to produce and secrete enough insulin as the disease progresses. However, clinical treatments based solely on insulin secretion and action have had limited success. The focus is therefore shifting towards α-cells, in particular to the dysregulated secretion of glucagon. Our qualitative electron-microscopy-based observations gave an indication that mitochondria in α-cells are altered in Western-diet-induced T2DM. In particular, α-cells extracted from mouse pancreatic tissue showed a lower density of mitochondria, a less expressed matrix and a lower number of cristae. These deformities in mitochondrial ultrastructure imply a decreased efficiency in mitochondrial ATP production, which prompted us to theoretically explore and clarify one of the most challenging problems associated with T2DM, namely the lack of glucagon secretion in hypoglycaemia and its oversecretion at high blood glucose concentrations. To this purpose, we constructed a novel computational model that links α-cell metabolism with their electrical activity and glucagon secretion. Our results show that defective mitochondrial metabolism in α-cells can account for dysregulated glucagon secretion in T2DM, thus improving our understanding of T2DM pathophysiology and indicating possibilities for new clinical treatments.
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Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
| | - Saška Lipovšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000 Maribor, Slovenia
- Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Gerd Leitinger
- Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Ismael Valladolid-Acebes
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, 171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, 171 76 Stockholm, Sweden
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Matjaž Perc
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Complexity Science Hub Vienna, 1080 Vienna, Austria
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Education, University of Maribor, 2000 Maribor, Slovenia
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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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Insulin Secretion Depends on Intra-islet Glucagon Signaling. Cell Rep 2019; 25:1127-1134.e2. [PMID: 30380405 DOI: 10.1016/j.celrep.2018.10.018] [Citation(s) in RCA: 215] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 06/11/2018] [Accepted: 10/02/2018] [Indexed: 12/20/2022] Open
Abstract
The intra-islet theory states that glucagon secretion is suppressed when insulin secretion is stimulated, but glucagon's role in intra-islet paracrine regulation is controversial. This study investigated intra-islet functions of glucagon in mice. We examined glucagon-induced insulin secretion using isolated perfused pancreata from wild-type, GLP-1 receptor (GLP-1R) knockout, diphtheria toxin-induced proglucagon knockdown, β cell-specific glucagon receptor (Gcgr) knockout, and global Gcgr knockout (Gcgr-/-) mice. We found that glucagon stimulates insulin secretion through both Gcgr and GLP-1R. Moreover, loss of either Gcgr or GLP-1R does not change insulin responses, whereas combined blockage of both receptors significantly reduces insulin secretion. Active GLP-1 is identified in pancreatic perfusate from Gcgr-/- but not wild-type mice, suggesting that β cell GLP-1R activation results predominantly from glucagon action. Our results suggest that combined activity of glucagon and GLP-1 receptors is essential for β cell secretory responses, emphasizing a role for paracrine intra-islet glucagon actions to maintain appropriate insulin secretion.
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Noguchi GM, Huising MO. Integrating the inputs that shape pancreatic islet hormone release. Nat Metab 2019; 1:1189-1201. [PMID: 32694675 PMCID: PMC7378277 DOI: 10.1038/s42255-019-0148-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a complex mini organ composed of a variety of endocrine cells and their support cells, which together tightly control blood glucose homeostasis. Changes in glucose concentration are commonly regarded as the chief signal controlling insulin-secreting beta cells, glucagon-secreting alpha cells and somatostatin-secreting delta cells. However, each of these cell types is highly responsive to a multitude of endocrine, paracrine, nutritional and neural inputs, which collectively shape the final endocrine output of the islet. Here, we review the principal inputs for each islet-cell type and the physiological circumstances in which these signals arise, through the prism of the insights generated by the transcriptomes of each of the major endocrine-cell types. A comprehensive integration of the factors that influence blood glucose homeostasis is essential to successfully improve therapeutic strategies for better diabetes management.
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Affiliation(s)
- Glyn M Noguchi
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA
| | - Mark O Huising
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA.
- Department of Physiology & Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, USA.
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Briant LJB, Dodd MS, Chibalina MV, Rorsman NJG, Johnson PRV, Carmeliet P, Rorsman P, Knudsen JG. CPT1a-Dependent Long-Chain Fatty Acid Oxidation Contributes to Maintaining Glucagon Secretion from Pancreatic Islets. Cell Rep 2019; 23:3300-3311. [PMID: 29898400 PMCID: PMC6581793 DOI: 10.1016/j.celrep.2018.05.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/19/2018] [Accepted: 05/11/2018] [Indexed: 12/30/2022] Open
Abstract
Glucagon, the principal hyperglycemic hormone, is secreted from pancreatic islet α cells as part of the counter-regulatory response to hypoglycemia. Hence, secretory output from α cells is under high demand in conditions of low glucose supply. Many tissues oxidize fat as an alternate energy substrate. Here, we show that glucagon secretion in low glucose conditions is maintained by fatty acid metabolism in both mouse and human islets, and that inhibiting this metabolic pathway profoundly decreases glucagon output by depolarizing α cell membrane potential and decreasing action potential amplitude. We demonstrate, by using experimental and computational approaches, that this is not mediated by the KATP channel, but instead due to reduced operation of the Na+-K+ pump. These data suggest that counter-regulatory secretion of glucagon is driven by fatty acid metabolism, and that the Na+-K+ pump is an important ATP-dependent regulator of α cell function. Glucagon secretion in low glucose is maintained by CPT1a-dependent FAO Loss of CPT1a-dependent FAO in mouse and human islets decreases glucagon secretion CPT1a-dependent FAO maintains glucagon secretion by supplying ATP to the Na+-K+-ATPase CPT1a-dependent FAO contributes to the counter-regulatory secretion of glucagon
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Affiliation(s)
- Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK; Department of Computer Science, University of Oxford, Oxford OX1 3QD, UK
| | - Michael S Dodd
- Department of Physiology, Anatomy & Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK; Faculty of Health and Life Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Margarita V Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
| | - Nils J G Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
| | - Paul R V Johnson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK; Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK; Metabolic Research, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Göteborg, Box 433, 405 30 Göteborg, Sweden
| | - Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK.
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Chen L, Chen XW, Huang X, Song BL, Wang Y, Wang Y. Regulation of glucose and lipid metabolism in health and disease. SCIENCE CHINA-LIFE SCIENCES 2019; 62:1420-1458. [PMID: 31686320 DOI: 10.1007/s11427-019-1563-3] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/15/2019] [Indexed: 02/08/2023]
Abstract
Glucose and fatty acids are the major sources of energy for human body. Cholesterol, the most abundant sterol in mammals, is a key component of cell membranes although it does not generate ATP. The metabolisms of glucose, fatty acids and cholesterol are often intertwined and regulated. For example, glucose can be converted to fatty acids and cholesterol through de novo lipid biosynthesis pathways. Excessive lipids are secreted in lipoproteins or stored in lipid droplets. The metabolites of glucose and lipids are dynamically transported intercellularly and intracellularly, and then converted to other molecules in specific compartments. The disorders of glucose and lipid metabolism result in severe diseases including cardiovascular disease, diabetes and fatty liver. This review summarizes the major metabolic aspects of glucose and lipid, and their regulations in the context of physiology and diseases.
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Affiliation(s)
- Ligong Chen
- School of Pharmaceutical Sciences, Beijing Advanced Innovation Center for Structural Biology, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Tsinghua University, Beijing, 100084, China.
| | - Xiao-Wei Chen
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Bao-Liang Song
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
| | - Yan Wang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
| | - Yiguo Wang
- MOE Key Laboratory of Bioinformatics, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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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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Guček A, Gandasi NR, Omar-Hmeadi M, Bakke M, Døskeland SO, Tengholm A, Barg S. Fusion pore regulation by cAMP/Epac2 controls cargo release during insulin exocytosis. eLife 2019; 8:41711. [PMID: 31099751 PMCID: PMC6557626 DOI: 10.7554/elife.41711] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 04/28/2019] [Indexed: 12/20/2022] Open
Abstract
Regulated exocytosis establishes a narrow fusion pore as initial aqueous connection to the extracellular space, through which small transmitter molecules such as ATP can exit. Co-release of polypeptides and hormones like insulin requires further expansion of the pore. There is evidence that pore expansion is regulated and can fail in diabetes and neurodegenerative disease. Here, we report that the cAMP-sensor Epac2 (Rap-GEF4) controls fusion pore behavior by acutely recruiting two pore-restricting proteins, amisyn and dynamin-1, to the exocytosis site in insulin-secreting beta-cells. cAMP elevation restricts and slows fusion pore expansion and peptide release, but not when Epac2 is inactivated pharmacologically or in Epac2-/- (Rapgef4-/-) mice. Consistently, overexpression of Epac2 impedes pore expansion. Widely used antidiabetic drugs (GLP-1 receptor agonists and sulfonylureas) activate this pathway and thereby paradoxically restrict hormone release. We conclude that Epac2/cAMP controls fusion pore expansion and thus the balance of hormone and transmitter release during insulin granule exocytosis. Insulin is the hormone that signals to the body to take up sugar from the blood. Specialized cells in the pancreas – known as β-cells – release insulin after a meal. Before that, insulin molecules are stored in tiny granules inside the β-cells; these granules must fuse with the cells’ surface membranes to release their contents. The first step in this process creates a narrow pore that allows small molecules, but not the larger insulin molecules, to seep out. The pore then widens to release the insulin. Since the small molecules are known to act locally in the pancreas, it is possible that this “molecular sieve” is biologically important. Yet it is not clear how the pore widens. One of the problems for people with type 2 diabetes is that they release less insulin into the bloodstream. Two kinds of drugs used to treat these patients work by stimulating β-cells to release their insulin. One way to achieve this is by raising the levels of a small molecule called cAMP, which is well known to help prepare insulin granules for release. The cAMP molecule also seems to slow the widening of the pore, and Gucek et al. have now investigated how this happens at a molecular level. By observing individual granules of human β-cells using a special microscope, Gucek et al. could watch how different drugs affect pore widening and content release. They also saw that cAMP activated a protein called Epac2, which then recruited two other proteins – amisyn and dynamin – to the small pores. These two proteins together then closed the pore, rather than expanding it to let insulin out. Type 2 diabetes patients sometimes have high levels of amisyn in their β-cells, which could explain why they do not release enough insulin. The microscopy experiments also revealed that two common anti-diabetic drugs activate Epac2 and prevent the pores from widening, thereby counteracting their positive effect on insulin release. The combined effect is likely a shift in the balance between insulin and the locally acting small molecules. These findings suggest that two common anti-diabetic drugs activate a common mechanism that may lead to unexpected outcomes, possibly even reducing how much insulin the β-cells can release. Future studies in mice and humans will have to investigate these effects in whole organisms.
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Affiliation(s)
- Alenka Guček
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Nikhil R Gandasi
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | | | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Anders Tengholm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Sebastian Barg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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Stamper IJ, Wang X. Integrated multiscale mathematical modeling of insulin secretion reveals the role of islet network integrity for proper oscillatory glucose-dose response. J Theor Biol 2019; 475:1-24. [PMID: 31078658 DOI: 10.1016/j.jtbi.2019.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 05/03/2019] [Accepted: 05/08/2019] [Indexed: 02/02/2023]
Abstract
The integrated multiscale mathematical model we present in this paper is built on two of our previous ones: a model of electrical oscillation in β-cells connected to neighboring cells within a three-dimensional (3D) network, and a model of glucose-induced β-cell intracellular insulin granule trafficking and insulin secretion. In order to couple these two models, we assume that the rate at which primed and release-ready insulin granules fuse at the cell membrane increases with the intracellular calcium concentration. Moreover, by assuming that the fraction of free KATP-channels decreases with increasing glucose concentration, we take into account the effect of glucose dose on membrane potential and, indirectly via the effect on the potential, on intracellular calcium. Numerical analysis of our new model shows that a single step increase in glucose concentration yields the experimentally observed characteristic biphasic insulin release. We find that the biphasic response is typically oscillatory in nature for low and moderate glucose concentrations. The plateau fraction (the time that the β-cells spend in their active firing phase) increases with increasing glucose dose, as does the total insulin secretion. At high glucose concentrations, the oscillations tend to vanish due to a constantly elevated membrane potential of the β-cells. Our results also demonstrate how insulin secretion characteristics in various glucose protocols depend on the degree of β-cell loss, highlighting the potential impact from disease. In particular, both the secretory capacity (average insulin secretion rate per β-cell) and the oscillatory response diminish as the islet cell network becomes compromised.
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Affiliation(s)
- I Johanna Stamper
- The Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
| | - Xujing Wang
- The Division of Diabetes, Endocrinology, and Metabolic Diseases (DEM), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), of the National Institutes of Health(NIH), Bethesda, Maryland 20817, United States.
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Huising MO, van der Meulen T, Huang JL, Pourhosseinzadeh MS, Noguchi GM. The Difference δ-Cells Make in Glucose Control. Physiology (Bethesda) 2019; 33:403-411. [PMID: 30303773 DOI: 10.1152/physiol.00029.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The role of beta and α-cells to glucose control are established, but the physiological role of δ-cells is poorly understood. Delta-cells are ideally positioned within pancreatic islets to modulate insulin and glucagon secretion at their source. We review the evidence for a negative feedback loop between delta and β-cells that determines the blood glucose set point and suggest that local δ-cell-mediated feedback stabilizes glycemic control.
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Affiliation(s)
- Mark O Huising
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California , Davis, California.,Department of Physiology and Membrane Biology, School of Medicine, University of California , Davis, California
| | - Talitha van der Meulen
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California , Davis, California
| | - Jessica L Huang
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California , Davis, California
| | - Mohammad S Pourhosseinzadeh
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California , Davis, California
| | - Glyn M Noguchi
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California , Davis, California
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Zhao T, Huang Q, Su Y, Sun W, Huang Q, Wei W. Zinc and its regulators in pancreas. Inflammopharmacology 2019; 27:453-464. [PMID: 30756223 DOI: 10.1007/s10787-019-00573-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/02/2019] [Indexed: 12/12/2022]
Abstract
Studies have demonstrated that susceptibility to type 2 diabetes (T2D) is influenced by common polymorphism in the zinc transporter 8 gene SLC30A8, providing novel insight into the role of zinc in diabetes. Intriguingly, zinc participates in every step of the process, including insulin synthesis, crystallization, storage, secretion and signaling. Zinc deficiency or overload is associated with various disorders, such as diabetes, cardiovascular disease and obesity. Zinc supplementation is considered as an effective means of treating or preventing T2D in people with certain SLC30A8 genotypes. Three important protein families-zinc transporters (ZnTs), zinc importers (ZiPs) and metallothionein (MT)-participate in maintaining zinc homeostasis. Here, we review research on the physiological characteristics of zinc and its role in the pancreas and homeostasis regulation mechanisms, along with the latest research on the structure and function of ZnT/ZiP and MT. In addition, we summarize the advancements in research on SLC30A8 gene polymorphism in search of a mechanism to explain the relationship between the R risk allele and zinc transporter activity.
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Affiliation(s)
- Tianjiao Zhao
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Qiongfang Huang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Yangni Su
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Wuyi Sun
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China
| | - Qiong Huang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China.
| | - Wei Wei
- Key Laboratory of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei, 230032, China.
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Abstract
Findings from the past 10 years have placed the glucagon-secreting pancreatic α-cell centre stage in the development of diabetes mellitus, a disease affecting almost one in every ten adults worldwide. Glucagon secretion is reduced in patients with type 1 diabetes mellitus, increasing the risk of insulin-induced hypoglycaemia, but is enhanced in type 2 diabetes mellitus, exacerbating the effects of diminished insulin release and action on blood levels of glucose. A better understanding of the mechanisms underlying these changes is therefore an important goal. RNA sequencing reveals that, despite their opposing roles in the control of blood levels of glucose, α-cells and β-cells have remarkably similar patterns of gene expression. This similarity might explain the fairly facile interconversion between these cells and the ability of the α-cell compartment to serve as a source of new β-cells in models of extreme β-cell loss that mimic type 1 diabetes mellitus. Emerging data suggest that GABA might facilitate this interconversion, whereas the amino acid glutamine serves as a liver-derived factor to promote α-cell replication and maintenance of α-cell mass. Here, we survey these developments and their therapeutic implications for patients with diabetes mellitus.
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Affiliation(s)
| | - Pauline Chabosseau
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK.
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SGLT1 in pancreatic α cells regulates glucagon secretion in mice, possibly explaining the distinct effects of SGLT2 inhibitors on plasma glucagon levels. Mol Metab 2018; 19:1-12. [PMID: 30416006 PMCID: PMC6323192 DOI: 10.1016/j.molmet.2018.10.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/19/2018] [Accepted: 10/23/2018] [Indexed: 01/23/2023] Open
Abstract
Objectives It is controversial whether sodium glucose transporter (SGLT) 2 inhibitors increase glucagon secretion via direct inhibition of SGLT2 in pancreatic α cells. The role of SGLT1 in α cells is also unclear. We aimed to elucidate these points that are important not only for basic research but also for clinical insight. Methods Plasma glucagon levels were assessed in the high-fat, high-sucrose diet (HFHSD) fed C57BL/6J mice treated with dapagliflozin or canagliflozin. RT-PCR, RNA sequence, and immunohistochemistry were conducted to test the expression of SGLT1 and SGLT2 in α cells. We also used αTC1 cells and mouse islets to investigate the molecular mechanism by which SGLT1 modulates glucagon secretion. Results Dapagliflozin, but not canagliflozin, increased plasma glucagon levels in HFHSD fed mice. SGLT1 and glucose transporter 1 (GLUT1), but not SGLT2, were expressed in αTC1 cells, mouse islets and human islets. A glucose clamp study revealed that the plasma glucagon increase associated with dapagliflozin could be explained as a response to acute declines in blood glucose. Canagliflozin suppressed glucagon secretion by inhibiting SGLT1 in α cells; consequently, plasma glucagon did not increase with canagliflozin, even though blood glucose declined. SGLT1 effect on glucagon secretion depended on glucose transport, but not glucose metabolism. Islets from HFHSD and db/db mice displayed higher SGLT1 mRNA levels and lower GLUT1 mRNA levels than the islets from control mice. These expression levels were associated with higher glucagon secretion. Furthermore, SGLT1 inhibitor and siRNA against SGLT1 suppressed glucagon secretion in isolated islets. Conclusions These data suggested that a novel mechanism regulated glucagon secretion through SGLT1 in α cells. This finding possibly explained the distinct effects of dapagliflozin and canagliflozin on plasma glucagon levels in mice. SGLT1, but not SGLT2, is expressed in αTC1 cells, mouse islets and human islets. SGLT2 inhibitor dapagliflozin increases plasma glucagon in diabetic mice. SGLT2/low potency SGLT1 inhibitor canagliflozin does not increase plasma glucagon. Canagliflozin suppresses glucagon secretion by inhibiting SGLT1 in α cells. Higher expression of SGLT1 in islets is associated with higher glucagon secretion.
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