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Prasad MK, Mohandas S, Ramkumar KM. Dysfunctions, molecular mechanisms, and therapeutic strategies of pancreatic β-cells in diabetes. Apoptosis 2023:10.1007/s10495-023-01854-0. [PMID: 37273039 DOI: 10.1007/s10495-023-01854-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2023] [Indexed: 06/06/2023]
Abstract
Pancreatic beta-cell death has been established as a critical mediator in the progression of type 1 and type 2 diabetes mellitus. Beta-cell death is associated with exacerbating hyperglycemia and insulin resistance and paves the way for the progression of DM and its complications. Apoptosis has been considered the primary mechanism of beta-cell death in diabetes. However, recent pieces of evidence have implicated the substantial involvement of several other novel modes of cell death, including autophagy, pyroptosis, necroptosis, and ferroptosis. These distinct mechanisms are characterized by their unique biochemical features and often precipitate damage through the induction of cellular stressors, including endoplasmic reticulum stress, oxidative stress, and inflammation. Experimental studies were identified from PubMed literature on different modes of beta cell death during the onset of diabetes mellitus. This review summarizes current knowledge on the crucial pathways implicated in pancreatic beta cell death. The article also focuses on applying natural compounds as potential treatment strategies in inhibiting these cell death pathways.
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Affiliation(s)
- Murali Krishna Prasad
- Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, 603 203, Tamil Nadu, India
| | - Sundhar Mohandas
- Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, 603 203, Tamil Nadu, India
| | - Kunka Mohanram Ramkumar
- Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, 603 203, Tamil Nadu, India.
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Jetton TL, Flores-Bringas P, Leahy JL, Gupta D. SetD7 (Set7/9) is a novel target of PPARγ that promotes the adaptive pancreatic β-cell glycemic response. J Biol Chem 2021; 297:101250. [PMID: 34592314 PMCID: PMC8526774 DOI: 10.1016/j.jbc.2021.101250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 09/20/2021] [Accepted: 09/24/2021] [Indexed: 11/25/2022] Open
Abstract
Loss of functional pancreatic β-cell mass leads to type 2 diabetes (T2D), attributable to modified β-cell-dependent adaptive gene expression patterns. SetD7 is a histone methyltransferase enriched in pancreatic islets that mono- and dimethylates histone-3-lysine-4 (H3K4), promoting euchromatin modifications, and also maintains the regulation of key β-cell function and survival genes. However, the transcriptional regulation of this important epigenetic modifier is unresolved. Here we identified the nuclear hormone receptor peroxisome proliferator-activated receptor-gamma (PPARγ) as a major transcriptional regulator of SetD7 and provide evidence for direct binding and functionality of PPARγ in the SetD7 promoter region. Furthermore, constitutive shRNA-mediated PPARγ knockdown in INS-1 β-cells or pancreas-specific PPARγ deletion in mice led to downregulation of SetD7 expression as well as its nuclear enrichment. The relevance of the SetD7-PPARγ interaction in β-cell adaptation was tested in normoglycemic 60% partial pancreatectomy (Px) and hyperglycemic 90% Px rat models. Whereas a synergistic increase in islet PPARγ and SetD7 expression was observed upon glycemic adaptation post-60% Px, in hyperglycemic 90% Px rats, islet PPARγ, and PPARγ targets SetD7 and Pdx1 were downregulated. PPARγ agonist pioglitazone treatment in 90% Px rats partially restored glucose homeostasis and β-cell mass and enhanced expression of SetD7 and Pdx1. Collectively, these data provide evidence that the SetD7-PPARγ interaction serves as an important element of the adaptive β-cell response.
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Affiliation(s)
- Thomas L Jetton
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Patricio Flores-Bringas
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - John L Leahy
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Dhananjay Gupta
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA.
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Wang R, Li B, Lam SM, Shui G. Integration of lipidomics and metabolomics for in-depth understanding of cellular mechanism and disease progression. J Genet Genomics 2019; 47:69-83. [PMID: 32178981 DOI: 10.1016/j.jgg.2019.11.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/19/2019] [Accepted: 11/25/2019] [Indexed: 12/17/2022]
Abstract
Mass spectrometry (MS)-based omics technologies are now widely used to profile small molecules in multiple matrices to confer comprehensive snapshots of cellular metabolic phenotypes. The metabolomes of cells, tissues, and organisms comprise a variety of molecules including lipids, amino acids, sugars, organic acids, and so on. Metabolomics mainly focus on the hydrophilic classes, while lipidomics has emerged as an independent omics owing to the complexities of the organismal lipidomes. The potential roles of lipids and small metabolites in disease pathogenesis have been widely investigated in various human diseases, but system-level understanding is largely lacking, which could be partly attributed to the insufficiency in terms of metabolite coverage and quantitation accuracy in current analytical technologies. While scientists are continuously striving to develop high-coverage omics approaches, integration of metabolomics and lipidomics is becoming an emerging approach to mechanistic investigation. Integration of metabolome and lipidome offers a complete atlas of the metabolic landscape, enabling comprehensive network analysis to identify critical metabolic drivers in disease pathology, facilitating the study of interconnection between lipids and other metabolites in disease progression. In this review, we summarize omics-based findings on the roles of lipids and metabolites in the pathogenesis of selected major diseases threatening public health. We also discuss the advantages of integrating lipidomics and metabolomics for in-depth understanding of molecular mechanism in disease pathogenesis.
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Affiliation(s)
- Raoxu Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100101, China
| | - Bowen Li
- Lipidall Technologies Company Limited, Changzhou, 213000, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; Lipidall Technologies Company Limited, Changzhou, 213000, China.
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100101, China.
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Gupta D, Jetton TL, LaRock K, Monga N, Satish B, Lausier J, Peshavaria M, Leahy JL. Temporal characterization of β cell-adaptive and -maladaptive mechanisms during chronic high-fat feeding in C57BL/6NTac mice. J Biol Chem 2017; 292:12449-12459. [PMID: 28487366 DOI: 10.1074/jbc.m117.781047] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/29/2017] [Indexed: 12/18/2022] Open
Abstract
The onset of type 2 diabetes is characterized by transition from successful to failed insulin secretory compensation to obesity-related insulin resistance and dysmetabolism. Energy-rich diets in rodents are commonly studied models of compensatory increases in both insulin secretion and β cell mass. However, the mechanisms of these adaptive responses are incompletely understood, and it is also unclear why these responses eventually fail. We measured the temporal trends of glucose homeostasis, insulin secretion, β cell morphometry, and islet gene expression in C57BL/6NTac mice fed a 60% high-fat diet (HFD) or control diet for up to 16 weeks. A 2-fold increased hyperinsulinemia was maintained for the first 4 weeks of HFD feeding and then further increased through 16 weeks. β cell mass increased progressively starting at 4 weeks, principally through nonproliferative growth. Insulin sensitivity was not significantly perturbed until 11 weeks of HFD feeding. Over the first 8 weeks, we observed two distinct waves of increased expression of β cell functional and prodifferentiation genes. This was followed by activation of the unfolded protein response at 8 weeks and overt β cell endoplasmic reticulum stress at 12-16 weeks. In summary, β cell adaptation to an HFD in C57BL/6NTac mice entails early insulin hypersecretion and a robust growth phase along with hyperexpression of related genes that begin well before the onset of observed insulin resistance. However, continued HFD exposure results in cessation of gene hyperexpression, β cell functional failure, and endoplasmic reticulum stress. These data point to a complex but not sustainable integration of β cell-adaptive responses to nutrient overabundance, obesity development, and insulin resistance.
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Affiliation(s)
- Dhananjay Gupta
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Thomas L Jetton
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Kyla LaRock
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Navjot Monga
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Basanthi Satish
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - James Lausier
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Mina Peshavaria
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Jack L Leahy
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446.
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Abstract
In 1974, the discovery of a mouse and a rat that spontaneously developed hyperglycemia led to the development of 2 autoimmune diabetes models: nonobese diabetic (NOD) mouse and Bio-Breeding rat. These models have contributed to our understanding of autoimmune diabetes, provided tools to dissect autoimmune islet damage, and facilitated development of early detection, prevention, and treatment of type 1 diabetes. The genetic characterization, monoclonal antibodies, and congenic strains have made NOD mice especially useful.Although the establishment of the inbred NOD mouse strain was documented by Makino et al (Jikken Dobutsu. 1980;29:1-13), this review will focus on the not-as-well-known history leading to the discovery of a glycosuric female mouse by Yoshihiro Tochino. This discovery was spearheaded by years of effort by Japanese scientists from different disciplines and dedicated animal care personnel and by the support of the Shionogi Pharmaceutical Company, Osaka, Japan. The history is based on the early literature, mostly written in Japanese, and personal communications especially with Dr Tochino, who was involved in diabetes animal model development and who contributed to the release of NOD mice to the international scientific community. This article also reviews the scientific contributions made by the Bio-Breeding rat to autoimmune diabetes.
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Baena-Nieto G, Lomas-Romero IM, Mateos RM, Leal-Cosme N, Perez-Arana G, Aguilar-Diosdado M, Segundo C, Lechuga-Sancho AM. Ghrelin mitigates β-cell mass loss during insulitis in an animal model of autoimmune diabetes mellitus, the BioBreeding/Worcester rat. Diabetes Metab Res Rev 2017; 33. [PMID: 27103341 DOI: 10.1002/dmrr.2813] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 03/06/2016] [Accepted: 04/07/2016] [Indexed: 12/24/2022]
Abstract
BACKGROUND Ghrelin is a peptide hormone with pleiotropic effects. It stimulates cell proliferation and inhibits apoptosis-mediated cell death. It prevents diabetes mellitus in several models of chemical, surgical and biological toxic insults to pancreas in both in vivo and in vitro models and promotes glucose-stimulated insulin secretion under cytotoxic conditions. It has not yet been tested in vivo in an autoimmune model of diabetes with a persistent insult to the β-cell. Given the immunomodulating effects of ghrelin and its trophic effects on β-cells, we hypothesized that ghrelin treatment during the early stages of insulitis would delay diabetes onset. METHODS BioBreeding/Worcester male rats received ghrelin (10 ng/kg/day) before insulitis development. Glucose metabolism was characterized by glucose and insulin tolerance tests. β-cell mass, islet area, islet number, β-cell clusters, proliferation and apoptosis and degree of insulitis were analysed by histomorphometry. A Kaplan-Meier survival curve was plotted and analysed applying the log-rank (Mantel-Cox) test. RESULTS Ghrelin treatment significantly reduced the probability of developing diabetes in our model (p < 0.0001). It decreased islet infiltration and partially prevented β-cell mass loss, enabling the maintenance of β-cell neogenesis and proliferation rates. Furthermore, ghrelin treatment did not induce any metabolic perturbations. CONCLUSIONS These findings support the hypothesis that ghrelin delays the development of autoimmune diabetes by attenuating insulitis and supporting β-cell mass. GENERAL SIGNIFICANCE Ghrelin promotes β-cell viability and function through diverse mechanisms that may have significant implications for diabetes prevention, therapy and also transplant success of both islets and complete pancreas. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Gloria Baena-Nieto
- Department of Endocrinology and Nutrition, Puerta del Mar University Hospital, Cadiz, Spain
- Research Unit, Puerta del Mar University Hospital, Cadiz, Spain
| | - Isabel M Lomas-Romero
- Research Unit, Puerta del Mar University Hospital, Cadiz, Spain
- Andalusian Cellular Reprogramming Laboratory, Sevilla, Spain
| | - Rosa M Mateos
- Research Unit, Puerta del Mar University Hospital, Cadiz, Spain
- Department of Biotechnology, Biomedicine and Public Health, Cadiz University Medical School, Cadiz, Spain
| | - Noelia Leal-Cosme
- Department of Child and Mother Health and Radiology, Cadiz University Medical School, Cadiz, Spain
| | | | | | - Carmen Segundo
- "Salus Infirmorum" Faculty of Nursing, Cadiz University, Cadiz, Spain
| | - Alfonso M Lechuga-Sancho
- Research Unit, Puerta del Mar University Hospital, Cadiz, Spain
- Department of Child and Mother Health and Radiology, Cadiz University Medical School, Cadiz, Spain
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Zhang P, Kumar A, Katz LS, Li L, Paulynice M, Herman MA, Scott DK. Induction of the ChREBPβ Isoform Is Essential for Glucose-Stimulated β-Cell Proliferation. Diabetes 2015; 64:4158-70. [PMID: 26384380 PMCID: PMC4657577 DOI: 10.2337/db15-0239] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 09/05/2015] [Indexed: 12/17/2022]
Abstract
Carbohydrate-responsive element-binding protein (ChREBP) is a glucose-sensing transcription factor required for glucose-stimulated proliferation of pancreatic β-cells in rodents and humans. The full-length isoform (ChREBPα) has a low glucose inhibitory domain (LID) that restrains the transactivation domain when glucose catabolism is minimal. A novel isoform of ChREBP (ChREBPβ) was recently described that lacks the LID domain and is therefore constitutively and more potently active. ChREBPβ has not been described in β-cells nor has its role in glucose-stimulated proliferation been determined. We found that ChREBPβ is highly expressed in response to glucose, particularly with prolonged culture in hyperglycemic conditions. In addition, small interfering RNAs that knocked down ChREBPβ transcripts without affecting ChREBPα expression or activity decreased glucose-stimulated expression of carbohydrate response element-containing genes and glucose-stimulated proliferation in INS-1 cells and in isolated rat islets. Quantitative chromatin immunoprecipitation, electrophoretic mobility shift assays, and luciferase reporter assays were used to demonstrate that ChREBP binds to a newly identified powerful carbohydrate response element in β-cells and hepatocytes, distinct from that in differentiated 3T3-L1 adipocytes. We conclude that ChREBPβ contributes to glucose-stimulated gene expression and proliferation in β-cells, with recruitment of ChREBPα to tissue-specific elements of the ChREBPβ isoform promoter.
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Affiliation(s)
- Pili Zhang
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Anil Kumar
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Liora S Katz
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Lucy Li
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Martine Paulynice
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Donald K Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
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Abstract
Beta cell dysfunction and insulin resistance are inherently complex with their interrelation for triggering the pathogenesis of diabetes also somewhat undefined. Both pathogenic states induce hyperglycemia and therefore increase insulin demand. Beta cell dysfunction results from inadequate glucose sensing to stimulate insulin secretion therefore elevated glucose concentrations prevail. Persistently elevated glucose concentrations above the physiological range result in the manifestation of hyperglycemia. With systemic insulin resistance, insulin signaling within glucose recipient tissues is defective therefore hyperglycemia perseveres. Beta cell dysfunction supersedes insulin resistance in inducing diabetes. Both pathological states influence each other and presumably synergistically exacerbate diabetes. Preserving beta cell function and insulin signaling in beta cells and insulin signaling in the glucose recipient tissues will maintain glucose homeostasis.
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Affiliation(s)
- Marlon E. Cerf
- Diabetes Discovery Platform, South African Medical Research CouncilCape Town, South Africa
- *Correspondence: Marlon E. Cerf, Diabetes Discovery Platform, South African Medical Research Council, PO Box 19070, Tygerberg, Cape Town 7505, South Africa. e-mail:
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Metukuri MR, Zhang P, Basantani MK, Chin C, Stamateris RE, Alonso LC, Takane KK, Gramignoli R, Strom SC, O’Doherty RM, Stewart AF, Vasavada RC, Garcia-Ocaña A, Scott DK. ChREBP mediates glucose-stimulated pancreatic β-cell proliferation. Diabetes 2012; 61:2004-15. [PMID: 22586588 PMCID: PMC3402328 DOI: 10.2337/db11-0802] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Glucose stimulates rodent and human β-cell replication, but the intracellular signaling mechanisms are poorly understood. Carbohydrate response element-binding protein (ChREBP) is a lipogenic glucose-sensing transcription factor with unknown functions in pancreatic β-cells. We tested the hypothesis that ChREBP is required for glucose-stimulated β-cell proliferation. The relative expression of ChREBP was determined in liver and β-cells using quantitative RT-PCR (qRT-PCR), immunoblotting, and immunohistochemistry. Loss- and gain-of-function studies were performed using small interfering RNA and genetic deletion of ChREBP and adenoviral overexpression of ChREBP in rodent and human β-cells. Proliferation was measured by 5-bromo-2'-deoxyuridine incorporation, [(3)H]thymidine incorporation, and fluorescence-activated cell sorter analysis. In addition, the expression of cell cycle regulatory genes was measured by qRT-PCR and immunoblotting. ChREBP expression was comparable with liver in mouse pancreata and in rat and human islets. Depletion of ChREBP decreased glucose-stimulated proliferation in β-cells isolated from ChREBP(-/-) mice, in INS-1-derived 832/13 cells, and in primary rat and human β-cells. Furthermore, depletion of ChREBP decreased the glucose-stimulated expression of cell cycle accelerators. Overexpression of ChREBP amplified glucose-stimulated proliferation in rat and human β-cells, with concomitant increases in cyclin gene expression. In conclusion, ChREBP mediates glucose-stimulated proliferation in pancreatic β-cells.
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Affiliation(s)
- Mallikarjuna R. Metukuri
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Pili Zhang
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Mahesh K. Basantani
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Connie Chin
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rachel E. Stamateris
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Laura C. Alonso
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Karen K. Takane
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Roberto Gramignoli
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Stephen C. Strom
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robert M. O’Doherty
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andrew F. Stewart
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rupangi C. Vasavada
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Adolfo Garcia-Ocaña
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Donald K. Scott
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
- Corresponding author: Donald K. Scott,
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Torrejón-Escribano B, Escoriza J, Montanya E, Blasi J. Glucose-dependent changes in SNARE protein levels in pancreatic β-cells. Endocrinology 2011; 152:1290-9. [PMID: 21285315 DOI: 10.1210/en.2010-0898] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Prolonged exposure to high glucose concentration alters the expression of a set of proteins in pancreatic β-cells and impairs their capacity to secrete insulin. The cellular and molecular mechanisms that lie behind this effect are poorly understood. In this study, three either in vitro or in vivo models (cultured rat pancreatic islets incubated in high glucose media, partially pancreatectomized rats, and islets transplanted to streptozotozin-induced diabetic mice) were used to evaluate the dependence of the biological model and the treatment, together with the cell location (insulin granule or plasma membrane) of the affected proteins and the possible effect of sustained insulin secretion, on the glucose-induced changes in protein expression. In all three models, islets exposed to high glucose concentrations showed a reduced expression of secretory granule-associated vesicle-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins synaptobrevin/vesicle-associated membrane protein 2 and cellubrevin but minor or no significant changes in the expression of the membrane-associated target-SNARE proteins syntaxin1 and synaptosomal-associated protein-25 and a marked increase in the expression of synaptosomal-associated protein-23 protein. The inhibition of insulin secretion by the L-type voltage-dependent calcium channel nifedipine or the potassium channel activator diazoxide prevented the glucose-induced reduction in islet insulin content but not in vesicle-SNARE proteins, indicating that the granule depletion due to sustained exocytosis was not involved in the changes of protein expression induced by high glucose concentration. Altogether, the results suggest that high glucose has a direct toxic effect on the secretory pathway by decreasing the expression of insulin granule SNARE-associated proteins.
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Affiliation(s)
- Benjamín Torrejón-Escribano
- Departamento de Patologia i Terapèutica Experimental, Institut d'Investigació Biomèdica de Bellvitge-Universitat de Barcelona, Laboratori 4145, Campus de Bellvitge, Edifici del Pavelló de Govern, C/Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Barcelona, Spain
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11
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Pérez-Arana G, Blandino-Rosano M, Prada-Oliveira A, Aguilar-Diosdado M, Segundo C. Decrease in {beta}-cell proliferation precedes apoptosis during diabetes development in bio-breeding/worcester rat: beneficial role of Exendin-4. Endocrinology 2010; 151:2538-46. [PMID: 20410202 DOI: 10.1210/en.2009-1113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In autoimmune type 1 diabetes mellitus, proinflammatory cytokine-mediated apoptosis of beta-cells has been considered to be the first event directly responsible for beta-cell mass reduction. In the Bio-Breeding (BB) rat, an in vivo model used in the study of autoimmune diabetes, beta-cell apoptosis is observed from 9 wk of age and takes place after an insulitis period that begins at an earlier age. Previous studies by our group have shown an antiproliferative effect of proinflammatory cytokines on cultured beta-cells in Wistar rats, an effect that was partially reversed by Exendin-4, an analogue of glucagon-like peptide-1. In the current study, the changes in beta-cell apoptosis and proliferation during insulitis stage were also determined in pancreatic tissue sections in normal and thymectomized BB rats, as well as in Wistar rats of 5, 7, 9, and 11 wk of age. Although stable beta-cell proliferation in Wistar and thymectomized BB rats was observed along the course of the study, a decrease in beta-cell proliferation and beta-cell mass from the age of 5 wk, and prior to the commencement of apoptosis, was noted in BB rats. Exendin-4, in combination with anti-interferon-gamma antibody, induced a near-total recovery of beta-cell proliferation during the initial stages of insulitis. This highlights the importance of early intervention and, as well, the possibilities of new therapeutic approaches in preventing autoimmune diabetes by acting, initially, in the insulitis stage and, subsequently, on beta-cell regeneration and on beta-cell apoptosis.
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Affiliation(s)
- Gonzalo Pérez-Arana
- Investigation Unit and Endocrinology and Nutrition Service, Puerta del Mar Hospital, 11009 Cádiz, Spain
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Abstract
To unravel the cellular and molecular mechanisms involved in beta-cell renewal and expansion throughout life, several different experimental models were devised in the past. A number of experimental approaches and transgenic models have been engineered to trigger specifically pancreatic injury and thus explore regeneration. Globally, three main strategies are followed to induce pancreas damage: surgical, chemical and genetic. Some of the most relevant studies regarding these three approaches are briefly summarized in this short overview. Although significant progress has been achieved in recent years, there is much room for improving our understanding of many fundamental processes regulating beta-cell mass maintenance.
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Affiliation(s)
- P L Herrera
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland.
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13
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Pechhold K, Koczwara K, Zhu X, Harrison VS, Walker G, Lee J, Harlan DM. Blood glucose levels regulate pancreatic beta-cell proliferation during experimentally-induced and spontaneous autoimmune diabetes in mice. PLoS One 2009; 4:e4827. [PMID: 19287497 PMCID: PMC2654100 DOI: 10.1371/journal.pone.0004827] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 02/02/2009] [Indexed: 12/20/2022] Open
Abstract
Background Type 1 diabetes mellitus is caused by immune-mediated destruction of pancreatic β-cells leading to insulin deficiency, impaired intermediary metabolism, and elevated blood glucose concentrations. While at autoimmune diabetes onset a limited number of β-cells persist, the cells' regenerative potential and its regulation have remained largely unexplored. Using two mouse autoimmune diabetes models, this study examined the proliferation of pancreatic islet ß-cells and other endocrine and non-endocrine subsets, and the factors regulating that proliferation. Methodology and Principal Findings We adapted multi-parameter flow cytometry techniques (including DNA-content measurements and 5′-bromo-2′-deoxyuridine [BrdU] incorporation) to study pancreatic islet single cell suspensions. These studies demonstrate that β-cell proliferation rapidly increases at diabetes onset, and that this proliferation is closely correlated with the diabetic animals' elevated blood glucose levels. For instance, we show that when normoglycemia is restored by exogenous insulin or islet transplantation, the β-cell proliferation rate returns towards low levels found in control animals, yet surges when hyperglycemia recurs. In contrast, other-than-ß endocrine islet cells did not exhibit the same glucose-dependent proliferative responses. Rather, disease-associated alterations of BrdU-incorporation rates of δ-cells (minor decrease), and non-endocrine islet cells (slight increase) were not affected by blood glucose levels, or were inversely related to glycemia control after diabetes onset (α-cells). Conclusion We conclude that murine β-cells' ability to proliferate in response to metabolic need (i.e. rising blood glucose concentrations) is remarkably well preserved during severe, chronic β-cell autoimmunity. These data suggest that timely control of the destructive immune response after disease manifestation could allow spontaneous regeneration of sufficient β-cell mass to restore normal glucose homeostasis.
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Affiliation(s)
- Klaus Pechhold
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
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Gupta D, Jetton TL, Mortensen RM, Duan SZ, Peshavaria M, Leahy JL. In vivo and in vitro studies of a functional peroxisome proliferator-activated receptor gamma response element in the mouse pdx-1 promoter. J Biol Chem 2008; 283:32462-70. [PMID: 18718916 PMCID: PMC2583321 DOI: 10.1074/jbc.m801813200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 08/01/2008] [Indexed: 01/03/2023] Open
Abstract
We reported that peroxisome proliferator-activated receptor gamma (PPARgamma) transcriptionally regulates the beta-cell differentiation factor pancreatic duodenal homeobox (PDX)-1 based on in vitro RNA interference studies. We have now studied mice depleted of PPARgamma within the pancreas (PANC PPARgamma(-/-)) created by a Cre/loxP recombinase system, with Cre driven by the pdx-1 promoter. Male PANC PPARgamma(-/-) mice were hyperglycemic at 8 weeks of age (8.1+/-0.2 mM versus 6.4+/-0.3 mM, p=0.009) with islet cytoarchitecture and pancreatic mass of islet beta-cells that were indistinguishable from the controls. Islet PDX-1 mRNA (p=0.001) and protein levels (p=0.003) were lowered 60 and 40%, respectively, in tandem with impaired glucose-induced insulin secretion and loss of thiazolidinedione-induced increase in PDX-1 expression. We next identified a putative PPAR-response element (PPRE) in the mouse pdx-1 promoter with substantial homology to the corresponding region of the human PDX-1 promoter. Electrophoretic mobility supershift assays with nuclear extracts from beta-cell lines and mouse islets, also in vitro translated PPARgamma and retinoid X receptor, and chromatin immunoprecipitation analysis demonstrated specific binding of PPARgamma and retinoid X receptor to the human and mouse pdx-1 x PPREs. Transient transfection assays of beta-cells with reporter constructs of mutated PPREs showed dramatically reduced pdx-1 promoter activity. In summary, we have presented in vivo and in vitro evidence showing PPARgamma regulation of pdx-1 transcription in beta-cells, plus our results support an important regulatory role for PPARgamma in beta-cell physiology and thiazolidinedione pharmacology of type 2 diabetes.
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Affiliation(s)
- Dhananjay Gupta
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Vermont, Burlington, Vermont 05405, USA
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15
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Abstract
The control of glucose metabolism by pancreatic endocrine cells throughout life relies on a tight regulation of the mass of insulin-producing beta-cells. How this homoeostasis is achieved is not well understood. Over the last few years, experimental rodent models with altered beta-cell mass, and, more recently, new transgenic approaches designed to tackle this problem, have provided abundant information. Processes such as beta-cell proliferation and apoptosis, or even beta-cell differentiation from poorly characterized progenitor cells, whether immature or differentiated, appear to be implicated. A complex picture is thus emerging in which the nature of the pancreatic lesion appears to determine the kind of regenerative response. The environment formed by acinar and ductal cells, and also by vascular and neuronal structures, which surround islets and penetrate into their beta-cell core, might play crucial roles so far unsuspected, which should be explored in the near future.
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16
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Moibi JA, Gupta D, Jetton TL, Peshavaria M, Desai R, Leahy JL. Peroxisome proliferator-activated receptor-gamma regulates expression of PDX-1 and NKX6.1 in INS-1 cells. Diabetes 2007; 56:88-95. [PMID: 17192469 DOI: 10.2337/db06-0948] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In the 60% pancreatectomy (Px) rat model of beta-cell adaptation, normoglycemia is maintained by an initial week of beta-cell hyperplasia that ceases and is followed by enhanced beta-cell function. It is unknown how this complex series of events is regulated. We studied isolated islets and pancreas sections from 14-day post-Px versus sham-operated rats and observed a doubling of beta-cell nuclear peroxisome proliferator-activated receptor (PPAR)-gamma protein, along with a 2-fold increase in nuclear pancreatic duodenal homeobox (Pdx)-1 protein and a 1.4-fold increase in beta-cell nuclear Nkx6.1 immunostaining. As PPAR-gamma activation is known to both lower proliferation and have prodifferentiation effects in many tissues, we studied PPAR-gamma actions in INS-1 cells. A 3-day incubation with the PPAR-gamma agonist troglitazone reduced proliferation and increased Pdx-1 and Nkx6.1 immunostaining, along with glucokinase and GLUT2. Also, a 75% knockdown of PPAR-gamma using RNA interference lowered the mRNA levels of Pdx-1, glucokinase, GLUT2, and proinsulin II by more than half. Our results show a dual effect of PPAR-gamma in INS-1 cells: to curtail proliferation and promote maturation, the latter via enhanced expression of Pdx-1 and Nkx6.1. Additional studies are needed to determine whether there is a regulatory role for PPAR-gamma signaling in the beta-cell adaptation following a 60% Px in rats.
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Affiliation(s)
- Jacob A Moibi
- Cross Cancer Institute, University of Alberta, Edmonton, Canada
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17
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Shankar PNE, Joseph A, Paulose CS. Decreased [3H] YM-09151-2 binding to dopamine D2 receptors in the hypothalamus, brainstem and pancreatic islets of streptozotocin-induced diabetic rats. Eur J Pharmacol 2006; 557:99-105. [PMID: 17174299 DOI: 10.1016/j.ejphar.2006.11.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 11/06/2006] [Accepted: 11/09/2006] [Indexed: 11/22/2022]
Abstract
In the present study dopamine was measured in the hypothalamus, brainstem, pancreatic islets and plasma, using HPLC. Dopamine D2 receptor changes in the hypothalamus, brainstem and pancreatic islets were studied using [3H] YM-09151-2 in streptozotocin-induced diabetic and insulin-treated diabetic rats. There was a significant decrease in dopamine content in the hypothalamus (P<0.001), brainstem (P<0.001), pancreatic islets (P<0.001) and plasma (P<0.001) in diabetic rats when compared to control. Scatchard analysis of [3H] YM-09151-2 in the hypothalamus of diabetic rats showed a significant decrease in Bmax (P<0.001) and Kd, showing an increased affinity of D2 receptors when compared to control. Insulin treatment did not completely reverse the changes that occurred during diabetes. There was a significant decrease in Bmax (P<0.01) with decreased affinity in the brainstem of diabetic rats. The islet membrane preparation of diabetic rats showed a significant decrease (P<0.001) in the binding of [3H] YM-09151-2 with decreased Kd (P<0.001) compared to control. The increase in affinity of D2 receptors in hypothalamus and pancreatic islets and the decreased affinity in brainstem were confirmed by competition analysis. Thus our results suggest that the decreased dopamine D2 receptor function in the hypothalamus, brainstem and pancreas affects insulin secretion in diabetic rats, which has immense clinical relevance to the management of diabetes.
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Affiliation(s)
- P N Eswar Shankar
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin-682 022, Kerala, India
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18
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Ani Das V, Savitha B, Paulose CS. Decreased alpha1-adrenergic receptor binding in the cerebral cortex and brain stem during pancreatic regeneration in rats. Neurochem Res 2006; 31:727-34. [PMID: 16791475 DOI: 10.1007/s11064-006-9073-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2006] [Indexed: 10/24/2022]
Abstract
The purpose of this study was to investigate the role of brain alpha1-adrenergic receptor binding in the rat model of pancreatic regeneration using 60-70% pancreatectomy. The alpha1-adrenergic receptors kinetics was studied in the cerebral cortex and brain stem of sham operated, 72 h pancreatectomised and 7 days pancreatectomised rats. Scatchard analysis with [3H]prazosin in cerebral cortex and brain stem showed a significant decrease (P < 0.01), (P < 0.05) in maximal binding (Bmax) with a significant decrease (P < 0.001), (P < 0.01) in the Kd in 72 h pancreatectomised rats compared with sham respectively. Competition analysis in cerebral cortex and brain stem showed a shift in affinity during pancreatic regeneration. The sympathetic activity was decreased as indicated by the significantly decreased norepinephrine level in the plasma (P < 0.001), cerebral cortex (P < 0.01) and brain stem (P < 0.001) of 72 h pancreatectomised rats compared to sham. Thus, from our results it is suggested that the central alpha1-adrenergic receptors have a functional role in the pancreatic regeneration mediated through the sympathetic pathway.
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Affiliation(s)
- V Ani Das
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682 022 Kerala, India
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19
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Das VA, Chathu F, Paulose CS. Decreased alpha2-adrenergic receptor in the brain stem and pancreatic islets during pancreatic regeneration in weanling rats. Life Sci 2006; 79:1507-13. [PMID: 16737719 DOI: 10.1016/j.lfs.2006.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2006] [Revised: 04/17/2006] [Accepted: 04/20/2006] [Indexed: 10/24/2022]
Abstract
Sympathetic stimulation inhibits insulin secretion. alpha(2)-Adrenergic receptor is known to have a regulatory role in the sympathetic function. We investigated the changes in the alpha(2)-adrenergic receptors in the brain stem and pancreatic islets using [(3)H]Yohimbine during pancreatic regeneration in weanling rats. Brain stem and pancreatic islets of experimental rats showed a significant decrease (p<0.001) in norepinephrine (NE) content at 72 h after partial pancreatectomy. The epinephrine (EPI) content showed a significant decrease (p<0.001) in pancreatic islets while it was not detected in brain stem at 72 h after partial pancreatectomy. Scatchard analysis of [(3)H]Yohimbine showed a significant decrease (p<0.05) in B(max) and K(d) at 72 h after partial pancreatectomy in the brain stem. In the pancreatic islets, Scatchard analysis of [(3)H]Yohimbine showed a significant decrease (p<0.001) in B(max) and K(d) (p<0.05) at 72 h after partial pancreatectomy. The binding parameters reversed to near sham by 7 days after pancreatectomy both in brain stem and pancreatic islets. This shows that pancreatic insulin secretion is influenced by central nervous system inputs from the brain stem. In vitro studies with yohimbine showed that the alpha(2)-adrenergic receptors are inhibitory to islet DNA synthesis and insulin secretion. Thus our results suggest that decreased alpha(2)-adrenergic receptors during pancreatic regeneration functionally regulate insulin secretion and pancreatic beta-cell proliferation in weanling rats.
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Affiliation(s)
- V Ani Das
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin-682 022, Kerala, India
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20
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Mohanan VV, Khan R, Paulose CS. Hypothalamic 5-HT functional regulation through 5-HT1A and 5-HT2C receptors during pancreatic regeneration. Life Sci 2005; 78:1603-9. [PMID: 16253282 DOI: 10.1016/j.lfs.2005.07.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2005] [Accepted: 07/26/2005] [Indexed: 01/21/2023]
Abstract
5-HT receptors are predominantly located in the brain and are involved in pancreatic function and cell proliferation through sympathetic nervous system. The objective of this study was to investigate the role of hypothalamic 5-HT, 5-HT1A and 5-HT2C receptor binding and gene expression in rat model of pancreatic regeneration using 60% pancreatectomy. The pancreatic regeneration was evaluated by 5-HT content, 5-HT1A and 5-HT2C receptor gene expression in the hypothalamus of sham operated, 72 h and 7 days pancreatectomised rats. 5-HT content was quantified by HPLC. 5-HT1A receptor assay was done by using specific agonist [3H]8-OH DPAT. 5-HT2C receptor assay was done by using specific antagonist [3H]mesulergine. The expression of 5-HT1A and 5-HT2C receptor gene was analyzed by RT-PCR. 5-HT content was higher in the hypothalamus of 72 h pancreatectomised rats. 5-HT1A and 5-HT2C receptors were down-regulated in the hypothalamus. RT-PCR analysis revealed decreased 5-HT1A and 5-HT2C receptor mRNA expression. The 5-HT1A and 5-HT2C receptors gene expression in the 7 days pancreatectomised rats reversed to near sham level. This study is the first to identify 5-HT1A and 5-HT2C receptor gene expression in the hypothalamus during pancreatic regeneration in rats. Our results suggest the hypothalamic serotonergic receptor functional regulation during pancreatic regeneration.
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Affiliation(s)
- Valiya Veettil Mohanan
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin-682 022, Kerala, India
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21
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Mohanan VV, Kaimal SB, Paulose CS. Decreased 5-HT1A receptor gene expression and 5-HT1A receptor protein in the cerebral cortex and brain stem during pancreatic regeneration in rats. Neurochem Res 2005; 30:25-32. [PMID: 15756929 DOI: 10.1007/s11064-004-9682-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The present study was to investigate the role of central 5-HT and 5-HT(1A) receptor binding and gene expression in a rat model of pancreatic regeneration using 60% pancreatectomy. The pancreatic regeneration was evaluated by 5-HT content and 5-HT(1A) receptor gene expression in the cerebral cortex (CC) and brain stem (BS) of sham operated, 72 h and 7 days pancreatectomised rats. 5-HT content significantly increased in the CC (P < 0.01) and BS (P < 0.05) of 72 h pancreatectomised rats. Sympathetic activity was decreased as indicated by the significantly decreased norepinephrine (NE) and epinephrine (EPI) level (P < 0.001 and P < 0.05) in the plasma of 72 h pancreatectomised rats. 5-HT(1A) receptor density and affinity was decreased in the CC (P < 0.01) and BS (P < 0.01). These changes correlated with a diminished 5-HT(1A) receptor mRNA expression in the brain regions studied. Our results suggest that the brain 5-HT through 5-HT(1A) receptor has a functional role in the pancreatic regeneration through the sympathetic regulation.
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Affiliation(s)
- Valiya veettil Mohanan
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin-682 022, Kerala, India
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22
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Mohanan VV, Chathu F, Paulose CS. Decreased 5-HT2C receptor binding in the cerebral cortex and brain stem during pancreatic regeneration in rats. Mol Cell Biochem 2005; 272:165-70. [PMID: 16010984 DOI: 10.1007/s11010-005-7030-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The purpose of this study was to investigate the role of central 5-HT2C receptor binding in rat model of pancreatic regeneration using 60-70% pancreatectomy. The 5-HT and 5-HT2C receptor kinetics were studied in cerebral cortex and brain stem of sham operated, 72 h pancreatectomised and 7 days pancreatectomised rats. Scatchard analysis with [3H] mesulergine in cerebral cortex showed a significant decrease (p < 0.05) in maximal binding (Bmax) without any change in Kd in 72 h pancreatectomised rats compared with sham. The decreased Bmax reversed to sham level by 7 days after pancreatectomy. In brain stem, Scatchard analysis showed a significant decrease (p < 0.01) in Bmax with a significant increase (p < 0.01) in Kd. Competition analysis in brain stem showed a shift in affinity towards a low affinity. These parameters were reversed to sham level by 7 days after pancreatectomy. Thus the results suggest that 5-HT through the 5-HT2C receptor in the brain has a functional regulatory role in the pancreatic regeneration.
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Affiliation(s)
- Valiya Veettil Mohanan
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, India
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23
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Liu YQ, Han J, Epstein PN, Long YS. Enhanced rat beta-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway. Am J Physiol Endocrinol Metab 2005; 288:E471-8. [PMID: 15507531 DOI: 10.1152/ajpendo.00427.2004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Islet beta-cell proliferation is a very important component of beta-cell adaptation to insulin resistance and prevention of type 2 diabetes mellitus. However, we know little about the mechanisms of beta-cell proliferation. We now investigate the relationship between pyruvate carboxylase (PC) pathway activity and islet cell proliferation 5 days after 60% pancreatectomy (Px). Islet cell number, protein, and DNA content, indicators of beta-cell proliferation, were increased two- to threefold 5 days after Px. PC and pyruvate dehydrogenase (PDH) activities increased only approximately 1.3-fold; however, islet pyruvate content and malate release from isolated islet mitochondria were approximately threefold increased in Px islets. The latter is an indicator of pyruvate-malate cycle activity, indicating that most of the increased pyruvate was converted to oxaloacetate (OAA) through the PC pathway. The contents of OAA and malate, intermediates of the pyruvate-malate cycle, were also increased threefold. PDH and citrate content were only slightly increased. Importantly, the changes in cell proliferation parameters, glucose utilization, and oxidation and malate release were partially blocked by in vivo treatment with the PC inhibitor phenylacetic acid. Our results suggest that enhanced PC pathway in Px islets may have an important role in islet cell proliferation.
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Affiliation(s)
- Y Q Liu
- Kosair Children's Hospital Research Institute, Dept. of Pediatrics, Univ. of Louisville School of Medicine, 570 South Preston St., Suite 304, Louisville, KY 40292, USA.
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24
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Renuka TR, Savitha B, Paulose CS. Muscarinic M1 and M3 receptor binding alterations in pancreas during pancreatic regeneration of young rats. Endocr Res 2005; 31:259-70. [PMID: 16433246 DOI: 10.1080/07435800500406163] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The importance of muscarinic receptors in proliferation of different cell types and in insulin secretion from pancreatic beta cells has been extensively studied. However, the role of pancreatic muscarinic receptors during pancreatic regeneration has not yet been studied. For the first time, the functional status of the muscarinic M1 and M3 receptors in regeneration of the pancreas is investigated here. It is observed that the number and affinity of high-affinity muscarinic M3 receptors increased at the time of regeneration. The low-affinity M3 receptors also showed a similar trend. In the case of muscarinic M1 receptors, the receptor number increased with a decrease in affinity. We also observed an increase in the circulating insulin levels at the time of active regeneration. The in vitro studies confirmed that muscarinic receptors are stimulatory to insulin secretion. Our results suggest that the increased muscarinic M1 and M3 receptor subtypes stimulate insulin secretion and islet cell proliferation during the regeneration of pancreas.
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Affiliation(s)
- T R Renuka
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, 682 022, Kerala, India
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25
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Téllez N, Montolio M, Biarnés M, Castaño E, Soler J, Montanya E. Adenoviral overexpression of interleukin-1 receptor antagonist protein increases β-cell replication in rat pancreatic islets. Gene Ther 2004; 12:120-8. [PMID: 15578044 DOI: 10.1038/sj.gt.3302351] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The naturally occurring inhibitor of interleukin-1 (IL-1) action, interleukin-1 receptor antagonist protein (IRAP), binds to the type 1 IL-1 receptor but does not initiate IL-1 signal transduction. In this study, we have determined the effects of IL-1beta and IRAP overexpression on adult beta-cell replication and viability. IL-1beta reduced dramatically beta-cell replication in adult rat islets both at 5.5 mM (control: 0.29+/-0.04%; IL-1beta: 0.02+/-0.02%, P<0.05) and 22.2 mM glucose (control: 0.84+/-0.2%; IL-1beta: 0.05+/-0.05%, P<0.05). This effect was completely prevented in islets overexpressing IRAP after adenoviral gene transfer at 5.5 mM (Ad-IL-1Ra+IL-1beta: 0.84+/-0.1%, P<0.05) and 22.2 mM glucose (Ad-IL-1Ra+IL-1beta: 1.22+/-0.2%, P<0.05). Moreover, overexpression of IRAP increased glucose-stimulated beta-cell replication in the absence of IL-1beta exposure (Ad-IL-1Ra: 1.59+/-0.5%, P<0.05). beta-Cell death (TUNEL technique) was increased in IL-1beta-exposed islets but not in Ad-IL-1Ra-infected islets (control: 0.82+/-0.2%; control+IL-1beta: 1.77+/-0.2; IRAP: 0.61+/-0.2%; IRAP+IL-1beta: 0.86+/-0.1%, P<0.05). Comparable results were obtained by flow cytometry. To determine the effect of IRAP overexpression on beta-cell replication in vivo, Ad-IL-1Ra-transduced islets were transplanted into streptozotocin diabetic rats. beta-Cell replication was significantly increased in IRAP-overexpressing islet grafts (0.98+/-0.3%, P<0.05) compared to normal pancreas (0.35+/-0.02%), but not in control islet grafts (0.50+/-0.1%). This study shows that in addition to the effects of IL-1beta on beta-cell viability, this cytokine exerts a deleterious action on beta-cell replication, which can be prevented by IRAP overexpression, and provides support for the potential use of IRAP as a therapeutic tool.
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Affiliation(s)
- N Téllez
- Laboratory of Diabetes and Experimental Endocrinology, Endocrine Unit, Hospital Universitari Bellvitge, University of Barcelona, Barcelona, Spain
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Topp BG, McArthur MD, Finegood DT. Metabolic adaptations to chronic glucose infusion in rats. Diabetologia 2004; 47:1602-10. [PMID: 15349726 DOI: 10.1007/s00125-004-1493-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Accepted: 05/14/2004] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS Several studies have employed the chronic glucose infusion protocol to quantify the metabolic adaptations associated with a prolonged glucose challenge. However, the limited number of indices and time points reported by these studies has generated an incomplete picture of this process. In this study we aimed to generate an integrative and dynamic picture of the physiological adaptations that occur during chronic glucose infusion. METHODS Sprague-Dawley rats were infused with either 50% dextrose or saline (2 ml/h) for a period of between 0 and 6 days. Glucose, insulin and NEFA dynamics were determined from daily blood samples. Subsets of animals were killed daily for histological determination of beta cell mass, size and replication rates. The mathematical model of coupled beta cell mass, insulin and glucose (the betaIG model) was used to estimate insulin sensitivity, beta cell function and net neogenesis from this data. RESULTS Glucose-infused rats displayed transient hyperglycaemia, persistent hyperinsulinaemia and unchanged NEFA levels. Insulin sensitivity decreased by approximately 80% during the first day of glucose infusion, but had returned to pre-infusion levels by Day 3. Beta cell function was four to six times higher than in control rats throughout the experiment. Beta cell mass doubled over the 6 days of glucose infusion due to three phases of adaptation: (i) neogenesis; (ii) hypertrophy and hyperplasia; and (iii) continued hyperplasia coupled to a second wave of neogenesis. CONCLUSIONS/INTERPRETATION Contrary to the results reported for perfused pancreas and in vitro experiments, we found that chronic glucose infusion elevated beta cell function. The prediction of a second wave of beta cell neogenesis, coupled with our previous report of "focal areas" on Day 3, suggests the existence of delayed acinar-to-islet transdifferentiation.
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Affiliation(s)
- B G Topp
- Diabetes Research Laboratory, School of Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6
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27
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Dor Y, Brown J, Martinez OI, Melton DA. Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation. Nature 2004; 429:41-6. [PMID: 15129273 DOI: 10.1038/nature02520] [Citation(s) in RCA: 1651] [Impact Index Per Article: 82.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2003] [Accepted: 03/29/2004] [Indexed: 12/11/2022]
Abstract
How tissues generate and maintain the correct number of cells is a fundamental problem in biology. In principle, tissue turnover can occur by the differentiation of stem cells, as is well documented for blood, skin and intestine, or by the duplication of existing differentiated cells. Recent work on adult stem cells has highlighted their potential contribution to organ maintenance and repair. However, the extent to which stem cells actually participate in these processes in vivo is not clear. Here we introduce a method for genetic lineage tracing to determine the contribution of stem cells to a tissue of interest. We focus on pancreatic beta-cells, whose postnatal origins remain controversial. Our analysis shows that pre-existing beta-cells, rather than pluripotent stem cells, are the major source of new beta-cells during adult life and after pancreatectomy in mice. These results suggest that terminally differentiated beta-cells retain a significant proliferative capacity in vivo and cast doubt on the idea that adult stem cells have a significant role in beta-cell replenishment.
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Affiliation(s)
- Yuval Dor
- Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, Harvard University, 7 Divinity Avenue, Cambridge, Massachusetts 02138, USA
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28
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Broca C, Brennan L, Petit P, Newsholme P, Maechler P. Mitochondria-derived glutamate at the interplay between branched-chain amino acid and glucose-induced insulin secretion. FEBS Lett 2003; 545:167-72. [PMID: 12804769 DOI: 10.1016/s0014-5793(03)00526-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In pancreatic beta-cells, glutamate has been proposed to mediate insulin secretion as a glucose-derived factor, although it is also considered for its sole catabolic function. Hence, changes in cellular glutamate levels are a matter of debate. Here, we investigated the effects of glucose and the glutamate precursor glutamine on kinetics of glutamate levels together with insulin secretion in INS-1E beta-cells. Preincubation at low (1 mM) glucose resulted in reduced cellular glutamate levels, which were doubled by exposure to glutamine. In glutamine-deprived cells, 5 mM glucose restored glutamate concentrations. Incubation at 15 mM glucose increased cellular glutamate, along with stimulation of insulin secretion, following both glutamine-free and glutamine-rich preincubations. Nuclear magnetic resonance (NMR) spectroscopy of INS-1E cells exposed to 15 mM D-[1-(13)C]glucose revealed glutamate as the major glucose metabolic product. Branched-chain amino acids, such as leucine, reduced cellular glutamate levels at low and intermediate glucose. This study demonstrates that glucose stimulates glutamate generation, whereas branched-chain amino acids promote competitive glutamate expenditure.
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Affiliation(s)
- Christophe Broca
- DBC-9100, Department of Internal Medicine, University Medical Centre, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland
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