151
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Busiah K, Verkarre V, Cavé H, Scharfmann R, Polak M. Human pancreas endocrine cell populations and activating ABCC8 mutations. Horm Res Paediatr 2015; 82:59-64. [PMID: 24941889 DOI: 10.1159/000360004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 01/20/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Activating mutations in the ABCC8 gene encoding the KATP channel subunit SUR1 cause β-cell dysfunction with non-autoimmune diabetes mellitus in neonates or infants. We investigated whether activating ABCC8 mutations affect endocrine pancreas development. METHODS We studied a male infant with compound heterozygous ABCC8 mutations (p.Arg826Trp/p.Ile93Thr) causing neonatal diabetes mellitus. He died of ketoacidosis. Postmortem pancreas specimens were evaluated by fluorescent microscopy after immunostaining for insulin, glucagon, somatostatin, and PCNA, and Hoechst 33342 nuclear staining. We compared the findings to those in 5 age-matched controls. RESULTS The number of islets was decreased and the number of single or small clusters of insulin cells increased in the patient compared to the age-matched controls. The islets in the patient had an insulin-cell core surrounded by intermingled glucagon and somatostatin cells. The insulin/Hoechst surface ratio was decreased and the glucagon/Hoechst surface ratio increased in the patient (4.3 and 8.8%, respectively) versus the controls (8.2 and 3.1%, respectively). Somatostatin surface staining was similar in the patient and controls (4 vs. 4.7%). PCNA staining was increased 3- to 3.5-fold, indicating increased insulin-cell proliferation compared to controls. CONCLUSION Activating ABCC8 mutations impaired the balance between β and α cells in the patient, suggesting an effect on β-cell mass development.
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Affiliation(s)
- Kanetee Busiah
- INSERM U1016, Université Paris Descartes, Sorbonne Paris Cité (UPD-SPC), Department of Paediatric Endocrinology, Gynaecology, and Diabetology, Necker Enfants-Malades Teaching Hospital (NEMTH), Assistance Publique-Hôpitaux de Paris (APHP), IMAGINE Affiliate, Paris, France
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152
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Visa M, Alcarraz‐Vizán G, Montane J, Cadavez L, Castaño C, Villanueva‐Peñacarrillo ML, Servitja J, Novials A. Islet amyloid polypeptide exerts a novel autocrine action in β‐cell signaling and proliferation. FASEB J 2015; 29:2970-9. [DOI: 10.1096/fj.15-270553] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/04/2015] [Indexed: 01/31/2023]
Affiliation(s)
- Montse Visa
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Gema Alcarraz‐Vizán
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Joel Montane
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Lisa Cadavez
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Carlos Castaño
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - María Luisa Villanueva‐Peñacarrillo
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
- Department of Metabolism, Nutrition and HormonesInstituto de Investigación Sanitaria de la Fundación Jiménez DíazMadridSpain
| | - Joan‐Marc Servitja
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
| | - Anna Novials
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i SunyerBarcelonaSpain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas AsociadasBarcelonaSpain
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153
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ANGPTL8/betatrophin does not control pancreatic beta cell expansion. Cell 2015; 159:691-6. [PMID: 25417115 DOI: 10.1016/j.cell.2014.09.027] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/02/2014] [Accepted: 09/10/2014] [Indexed: 02/06/2023]
Abstract
Recently, it was reported that angiopoietin-like protein 8 (ANGPTL8) was the long-sought "betatrophin" that could control pancreatic beta cell proliferation. However, studies of Angptl8(?/?) mice revealed profound reduction of triglyceride levels, but no abnormalities in glucose homeostasis. We now report that Angptl8(?/?) mice undergo entirely normal beta cell expansion in response to insulin resistance resulting from either a high-fat diet or from the administration of the insulin receptor antagonist S961. Furthermore, overexpression of ANGPTL8 in livers of mice doubles plasma triglyceride levels, but does not alter beta cell expansion nor glucose metabolism. These data indicate that ANGPTL8 does not play a role in controlling beta cell growth, nor can it be given to induce such expansion. The findings that plasma triglyceride levels are reduced by Angptl8 deletion and increased following ANGPTL8 overexpression support the possibility that inhibition of ANGPTL8 represents a therapeutic strategy for hypertriglyceridemia.
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154
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Taylor BL, Benthuysen J, Sander M. Postnatal β-cell proliferation and mass expansion is dependent on the transcription factor Nkx6.1. Diabetes 2015; 64:897-903. [PMID: 25277396 PMCID: PMC4338594 DOI: 10.2337/db14-0684] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
All forms of diabetes are characterized by a loss of functional β-cell mass, and strategies for expanding β-cell mass could have significant therapeutic benefit. We have recently identified the transcription factor Nkx6.1 as an essential maintenance factor of the functional β-cell state. In addition, Nkx6.1 has been proposed to control β-cell proliferation, but a role for Nkx6.1 in regulating β-cell mass has not been demonstrated. Here, we show that Nkx6.1 is required for postnatal β-cell mass expansion. Genetic inactivation of Nkx6.1 in newly formed β-cells caused a drastic decrease in early postnatal β-cell proliferation, leading to reduced β-cell mass and glucose intolerance. Interestingly, Nkx6.1 was dispensable for prenatal β-cell proliferation. We found that Nkx6.1 regulates the expression of several β-cell maturation markers as well as expression of the nutrient sensors Glut2 and Glp1r. Manifestation of the β-cell mass defect at the transition to postnatal feeding suggests that Nkx6.1 could regulate β-cell growth by enabling β-cells to respond to nutrient-dependent proliferation signals, such as glucose and Glp1. Identification of β-cell-intrinsic regulators that connect nutrient-sensing and proliferation suggests new therapeutic targets for expanding functional β-cell mass.
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Affiliation(s)
- Brandon L Taylor
- Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California, San Diego, La Jolla, CA
| | - Jacqueline Benthuysen
- Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California, San Diego, La Jolla, CA
| | - Maike Sander
- Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California, San Diego, La Jolla, CA
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155
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Stolovich-Rain M, Enk J, Vikesa J, Nielsen FC, Saada A, Glaser B, Dor Y. Weaning triggers a maturation step of pancreatic β cells. Dev Cell 2015; 32:535-45. [PMID: 25662175 DOI: 10.1016/j.devcel.2015.01.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 11/26/2014] [Accepted: 12/31/2014] [Indexed: 01/22/2023]
Abstract
Because tissue regeneration deteriorates with age, it is generally assumed that the younger the animal, the better it compensates for tissue damage. We have examined the effect of young age on compensatory proliferation of pancreatic β cells in vivo. Surprisingly, β cells in suckling mice fail to enter the cell division cycle in response to a diabetogenic injury or increased glycolysis. The potential of β cells for compensatory proliferation is acquired following premature weaning to normal chow, but not to a diet mimicking maternal milk. In addition, weaning coincides with enhanced glucose-stimulated oxidative phosphorylation and insulin secretion from islets. Transcriptome analysis reveals that weaning increases the expression of genes involved in replication licensing, suggesting a mechanism for increased responsiveness to the mitogenic activity of high glucose. We propose that weaning triggers a discrete maturation step of β cells, elevating both the mitogenic and secretory response to glucose.
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Affiliation(s)
- Miri Stolovich-Rain
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jonatan Enk
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jonas Vikesa
- Center for Genomic Medicine, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Finn Cilius Nielsen
- Center for Genomic Medicine, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Ann Saada
- Monique and Jacques Roboh Department of Genetic Research and the Department of Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Benjamin Glaser
- Endocrinology and Metabolism Service, Department of Internal Medicine, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Yuval Dor
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
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156
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Ljubicic S, Polak K, Fu A, Wiwczar J, Szlyk B, Chang Y, Alvarez-Perez JC, Bird GH, Walensky LD, Garcia-Ocaña A, Danial NN. Phospho-BAD BH3 mimicry protects β cells and restores functional β cell mass in diabetes. Cell Rep 2015; 10:497-504. [PMID: 25640178 DOI: 10.1016/j.celrep.2014.12.056] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 11/21/2014] [Accepted: 12/26/2014] [Indexed: 12/31/2022] Open
Abstract
Strategies that simultaneously enhance the survival and glucose responsiveness of insulin-producing β cells will greatly augment β cell replacement therapies in type 1 diabetes (T1D). We show that genetic and pharmacologic mimetics of the phosphorylated BCL-2 homology 3 (BH3) domain of BAD impart β-cell-autonomous protective effects in the face of stress stimuli relevant to β cell demise in T1D. Importantly, these benefits translate into improved engraftment of donor islets in transplanted diabetic mice, increased β cell viability in islet grafts, restoration of insulin release, and diabetes reversal. Survival of β cells in this setting is not merely due to the inability of phospho-BAD to suppress prosurvival BCL-2 proteins but requires its activation of the glucose-metabolizing enzyme glucokinase. Thus, BAD phospho-BH3 mimetics may prove useful in the restoration of functional β cell mass in diabetes.
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Affiliation(s)
- Sanda Ljubicic
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Klaudia Polak
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Accalia Fu
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Jessica Wiwczar
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Benjamin Szlyk
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Yigang Chang
- Division of Endocrinology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Juan C Alvarez-Perez
- Diabetes, Obesity and Metabolism Institute, The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Gregory H Bird
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA 02115, USA
| | - Loren D Walensky
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA 02115, USA
| | - Adolfo Garcia-Ocaña
- Diabetes, Obesity and Metabolism Institute, The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Nika N Danial
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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157
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Hanson MG, Wilde JJ, Moreno RL, Minic AD, Niswander L. Potassium dependent rescue of a myopathy with core-like structures in mouse. eLife 2015; 4. [PMID: 25564733 PMCID: PMC4309926 DOI: 10.7554/elife.02923] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 01/07/2015] [Indexed: 01/24/2023] Open
Abstract
Myopathies decrease muscle functionality. Mutations in ryanodine receptor 1 (RyR1) are often associated with myopathies with microscopic core-like structures in the muscle fiber. In this study, we identify a mouse RyR1 model in which heterozygous animals display clinical and pathological hallmarks of myopathy with core-like structures. The RyR1 mutation decreases sensitivity to activated calcium release and myoplasmic calcium levels, subsequently affecting mitochondrial calcium and ATP production. Mutant muscle shows a persistent potassium leak and disrupted expression of regulators of potassium homeostasis. Inhibition of KATP channels or increasing interstitial potassium by diet or FDA-approved drugs can reverse the muscle weakness, fatigue-like physiology and pathology. We identify regulators of potassium homeostasis as biomarkers of disease that may reveal therapeutic targets in human patients with myopathy of central core disease (CCD). Altogether, our results suggest that amelioration of potassium leaks through potassium homeostasis mechanisms may minimize muscle damage of myopathies due to certain RyR1 mutations.
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Affiliation(s)
- M Gartz Hanson
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Jonathan J Wilde
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Rosa L Moreno
- Department of Physiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Angela D Minic
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Lee Niswander
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
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158
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Chen Y, Wang X, Shao X. A Combination of Human Embryonic Stem Cell-Derived Pancreatic Endoderm Transplant with LDHA-Repressing miRNA Can Attenuate High-Fat Diet Induced Type II Diabetes in Mice. J Diabetes Res 2015; 2015:796912. [PMID: 26770982 PMCID: PMC4681983 DOI: 10.1155/2015/796912] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/22/2015] [Indexed: 01/03/2023] Open
Abstract
Type II diabetes mellitus (T2D) is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. The deficit and dysfunction of insulin secreting β-cell are signature symptom for T2D. Additionally, in pancreatic β-cell, a small group of genes which are abundantly expressed in most other tissues are highly selectively repressed. Lactate dehydrogenase A (LDHA) is one of such genes. Upregulation of LDHA is found in both human T2D and rodent T2D models. In this study, we identified a LDHA-suppressing microRNA (hsa-miR-590-3p) and used it together with human embryonic stem cell (hESC) derived pancreatic endoderm (PE) transplantation into a high-fat diet induced T2D mouse model. The procedure significantly improved glucose metabolism and other symptoms of T2D. Our findings support the potential T2D treatment using the combination of microRNA and hESC-differentiated PE cells.
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Affiliation(s)
- Yunya Chen
- Department of Endocrinology, Wuxi People's Hospital of Huishan District, 2 Zhanqian Street, Wuxi, Jiangsu 214187, China
| | - Xiujie Wang
- Department of Endocrinology, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, Jiangsu 215006, China
| | - Xinyu Shao
- Department of Endocrinology, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, Jiangsu 215006, China
- *Xinyu Shao:
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159
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Liang D, Zhang Y, Han J, Wang W, Liu Y, Li J, Jiang X. Embryonic stem cell-derived pancreatic endoderm transplant with MCT1-suppressing miR-495 attenuates type II diabetes in mice. Endocr J 2015. [PMID: 26211669 DOI: 10.1507/endocrj.ej15-0186] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Type 2 diabetes mellitus (T2D) is a chronic metabolic disorder resulting from defects in both insulin secretion and insulin activity. The deficit and dysfunction of insulin secreting β-cells are signature symptoms of T2D. Additionally, in pancreatic β-cells, a small group of genes that are abundantly expressed in most other tissues is highly selectively repressed. Monocarboxylate transporter 1 (MCT1) is one of these genes. In this study, we identified an MCT1-suppressing microRNA (hsa-miR-495) and used this microRNA together with human embryonic stem cell (hESC) derived pancreatic endoderm (PE) cells transplanted into a high-fat diet induced T2D mouse model. Glucose metabolism significantly improved and other symptoms of T2D were attenuated after the procedure. Our findings support the potential for T2D treatment using the combination of microRNA and hESC differentiated PE cells.
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Affiliation(s)
- Dong Liang
- Tianjin First Center Hospital, NO.24 Fukang Road, Nankai District, Tianjin 300192, China
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160
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Cai EP, Luk CT, Wu X, Schroer SA, Shi SY, Sivasubramaniyam T, Brunt JJ, Zacksenhaus E, Woo M. Rb and p107 are required for alpha cell survival, beta cell cycle control and glucagon-like peptide-1 action. Diabetologia 2014; 57:2555-65. [PMID: 25249236 DOI: 10.1007/s00125-014-3381-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 08/25/2014] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS Diabetes mellitus is characterised by beta cell loss and alpha cell expansion. Analogues of glucagon-like peptide-1 (GLP-1) are used therapeutically to antagonise these processes; thus, we hypothesised that the related cell cycle regulators retinoblastoma protein (Rb) and p107 were involved in GLP-1 action. METHODS We used small interfering RNA and adenoviruses to manipulate Rb and p107 expression in insulinoma and alpha-TC cell lines. In vivo we examined pancreas-specific Rb knockout, whole-body p107 knockout and Rb/p107 double-knockout mice. RESULTS Rb, but not p107, was downregulated in response to the GLP-1 analogue, exendin-4, in both alpha and beta cells. Intriguingly, this resulted in opposite outcomes of cell cycle arrest in alpha cells but proliferation in beta cells. Overexpression of Rb in alpha and beta cells abolished or attenuated the effects of exendin-4 supporting the important role of Rb in GLP-1 modulation of cell cycling. Similarly, in vivo, Rb, but not p107, deficiency was required for the beta cell proliferative response to exendin-4. Consistent with this finding, Rb, but not p107, was suppressed in islets from humans with diabetes, suggesting the importance of Rb regulation for the compensatory proliferation that occurs under insulin resistant conditions. Finally, while p107 alone did not have an essential role in islet homeostasis, when combined with Rb deletion, its absence potentiated apoptosis of both alpha and beta cells resulting in glucose intolerance and diminished islet mass with ageing. CONCLUSIONS/INTERPRETATION We found a central role of Rb in the dual effects of GLP-1 in alpha and beta cells. Our findings highlight unique contributions of individual Rb family members to islet cell proliferation and survival.
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Affiliation(s)
- Erica P Cai
- Toronto General Research Institute, University Health Network, 101 College Street, MaRS Centre/TMDT, Room 10-363, Toronto, ON, M5G 1L7, Canada
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161
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Nakamura A, Terauchi Y. Present status of clinical deployment of glucokinase activators. J Diabetes Investig 2014; 6:124-32. [PMID: 25802718 PMCID: PMC4364845 DOI: 10.1111/jdi.12294] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 12/14/2022] Open
Abstract
Glucokinase is one of four members of the hexokinase family of enzymes. Its expression is limited to the major organs (such as the pancreas, liver, brain and the gastrointestinal tract) that are thought to have an integrated role in glucose sensing. In the liver, phosphorylation of glucose by glucokinase promotes glycogen synthesis, whereas in the β-cells, it results in insulin release. Studies of glucokinase-linked genetically-modified mice and mutations in humans have illustrated the important roles played by glucokinase in whole-body glucose homeostasis, and suggest that the use of pharmacological agents that augment glucokinase activity could represent a viable treatment strategy in patients with type 2 diabetes. Since 2003, many glucokinase activators (GKAs) have been developed, and their ability to lower the blood glucose has been shown in several animal models of type 2 diabetes. Also, we and others have shown in mouse models that GKAs also have the effect of stimulating the proliferation of β-cells. However, the results of recent phase II trials have shown that GKAs lose their efficacy within several months of use, and that their use is associated with a high incidence of hypoglycemia; furthermore, patients treated with GKAs frequently developed dyslipidemia. A better understanding of the role of glucokinase in metabolic effects is required to resolve several issues identified in clinical trials.
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Affiliation(s)
- Akinobu Nakamura
- Division of Immunology and Metabolism, Hokkaido University Graduate School of Medicine Sapporo, Japan
| | - Yasuo Terauchi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University Yokohama, Japan
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162
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Bae CR, Hasegawa K, Akieda-Asai S, Kawasaki Y, Cha YS, Date Y. The short-term effects of soft pellets on lipogenesis and insulin sensitivity in rats. Prev Nutr Food Sci 2014; 19:164-9. [PMID: 25320713 PMCID: PMC4195621 DOI: 10.3746/pnf.2014.19.3.164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 09/15/2014] [Indexed: 12/29/2022] Open
Abstract
The purpose of the present study was to investigate the short-term effects of a 12-day, soft pellet (SP) diet with a 3-h restricted feeding schedule on caloric intake, body weight, lipid metabolism, and insulin sensitivity. Glucose and insulin levels were measured pre-, mid-, and post-feeding. The SP rats exhibited postprandial hyperglycemia compared to rats fed control pellets (CP). The insulin response of SP rats during a meal was significantly higher than that of CP rats. There were no significant differences in the hepatic triacylglycerol contents and lipogenesis gene mRNA levels of SP and CP rats. However, the hepatocytes of SP rats were slightly hypertrophic. In addition, histological analysis revealed that the pancreases of SP rats had more islet areas than those of CP rats. This study demonstrated that feeding an SP-only diet for 12 days induces glucose intolerance, suggesting that the consumption of absorbable food, like a soft diet, may trigger glucose metabolism insufficiency and lead to life-threatening diseases.
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Affiliation(s)
- Cho-Rong Bae
- Frontier Science Research Center, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan ; Department of Food Science and Human Nutrition, Chonbuk National University, Jeonbuk 561-756, Korea
| | - Kazuya Hasegawa
- Frontier Science Research Center, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Sayaka Akieda-Asai
- Frontier Science Research Center, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Yurie Kawasaki
- Frontier Science Research Center, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Youn-Soo Cha
- Department of Food Science and Human Nutrition, Chonbuk National University, Jeonbuk 561-756, Korea
| | - Yukari Date
- Frontier Science Research Center, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
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163
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Modi H, Cornu M, Thorens B. Glutamine stimulates biosynthesis and secretion of insulin-like growth factor 2 (IGF2), an autocrine regulator of beta cell mass and function. J Biol Chem 2014; 289:31972-31982. [PMID: 25271169 DOI: 10.1074/jbc.m114.587733] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
IGF2 is an autocrine ligand for the beta cell IGF1R receptor and GLP-1 increases the activity of this autocrine loop by enhancing IGF1R expression, a mechanism that mediates the trophic effects of GLP-1 on beta cell mass and function. Here, we investigated the regulation of IGF2 biosynthesis and secretion. We showed that glutamine rapidly and strongly induced IGF2 mRNA translation using reporter constructs transduced in MIN6 cells and primary islet cells. This was followed by rapid secretion of IGF2 via the regulated pathway, as revealed by the presence of mature IGF2 in insulin granule fractions and by inhibition of secretion by nimodipine and diazoxide. When maximally stimulated by glutamine, the amount of secreted IGF2 rapidly exceeded its initial intracellular pool and tolbutamide, and high K(+) increased IGF2 secretion only marginally. This indicates that the intracellular pool of IGF2 is small and that sustained secretion requires de novo synthesis. The stimulatory effect of glutamine necessitates its metabolism but not mTOR activation. Finally, exposure of insulinomas or beta cells to glutamine induced Akt phosphorylation, an effect that was dependent on IGF2 secretion, and reduced cytokine-induced apoptosis. Thus, glutamine controls the activity of the beta cell IGF2/IGF1R autocrine loop by increasing the biosynthesis and secretion of IGF2. This autocrine loop can thus integrate changes in feeding and metabolic state to adapt beta cell mass and function.
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Affiliation(s)
- Honey Modi
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Marion Cornu
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland.
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164
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Lee SH, Piran R, Keinan E, Pinkerton A, Levine F. Induction of β-cell replication by a synthetic HNF4α antagonist. Stem Cells 2014; 31:2396-407. [PMID: 23922283 DOI: 10.1002/stem.1496] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/19/2013] [Accepted: 07/07/2013] [Indexed: 01/09/2023]
Abstract
Increasing the number of β cells is critical to a definitive therapy for diabetes. Previously, we discovered potent synthetic small molecule antagonists of the nuclear receptor transcription factor HNF4α. The natural ligands of HNF4α are thought to be fatty acids. Because obesity, in which there are high circulating levels of free fatty acids, is one of the few conditions leading to β-cell hyperplasia, we tested the hypothesis that a potent HNF4α antagonist might stimulate β-cell replication. A bioavailable HNF4α antagonist was injected into normal mice and rabbits and β-cell ablated mice and the effect on β-cell replication was measured. In normal mice and rabbits, the compound induced β-cell replication and repressed the expression of multiple cyclin-dependent kinase inhibitors, including p16 that plays a critical role in suppressing β-cell replication. Interestingly, in β-cell ablated mice, the compound induced α- and δ-cell, in addition to β-cell replication, and β-cell number was substantially increased. Overall, the data presented here are consistent with a model in which the well-known effects of obesity and high fat diet on β-cell replication occur by inhibition of HNF4α. The availability of a potent synthetic HNF4α antagonist raises the possibility that this effect might be a viable route to promote significant increases in β-cell replication in diseases with reduced β-cell mass, including type I and type II diabetes.
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Affiliation(s)
- Seung-Hee Lee
- Sanford Children's Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
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165
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Zhao Z, Low YS, Armstrong NA, Ryu JH, Sun SA, Arvanites AC, Hollister-Lock J, Shah NH, Weir GC, Annes JP. Repurposing cAMP-modulating medications to promote β-cell replication. Mol Endocrinol 2014; 28:1682-97. [PMID: 25083741 DOI: 10.1210/me.2014-1120] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Loss of β-cell mass is a cardinal feature of diabetes. Consequently, developing medications to promote β-cell regeneration is a priority. cAMP is an intracellular second messenger that modulates β-cell replication. We investigated whether medications that increase cAMP stability or synthesis selectively stimulate β-cell growth. To identify cAMP-stabilizing medications that promote β-cell replication, we performed high-content screening of a phosphodiesterase (PDE) inhibitor library. PDE3, -4, and -10 inhibitors, including dipyridamole, were found to promote β-cell replication in an adenosine receptor-dependent manner. Dipyridamole's action is specific for β-cells and not α-cells. Next we demonstrated that norepinephrine (NE), a physiologic suppressor of cAMP synthesis in β-cells, impairs β-cell replication via activation of α(2)-adrenergic receptors. Accordingly, mirtazapine, an α(2)-adrenergic receptor antagonist and antidepressant, prevents NE-dependent suppression of β-cell replication. Interestingly, NE's growth-suppressive effect is modulated by endogenously expressed catecholamine-inactivating enzymes (catechol-O-methyltransferase and l-monoamine oxidase) and is dominant over the growth-promoting effects of PDE inhibitors. Treatment with dipyridamole and/or mirtazapine promote β-cell replication in mice, and treatment with dipyridamole is associated with reduced glucose levels in humans. This work provides new mechanistic insights into cAMP-dependent growth regulation of β-cells and highlights the potential of commonly prescribed medications to influence β-cell growth.
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Affiliation(s)
- Zhenshan Zhao
- Department of Medicine and Division of Endocrinology, Gerontology, and Metabolism (Z.Z., N.A.A., S.A.S., J.P.A.) and Stanford Center for Biomedical Informatics Research (Y.S.L.), Stanford University School of Medicine, Stanford, California 94306; Department of Stem Cell and Regenerative Biology (J.H.R., A.C.A.), Harvard University, Cambridge, Massachusetts 02138; and Section of Islet Cell and Regenerative Biology (J.H.-L., G.C.W.), Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115
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166
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Xu X, Wang G, Zhou T, Chen L, Chen J, Shen X. Novel approaches to drug discovery for the treatment of type 2 diabetes. Expert Opin Drug Discov 2014; 9:1047-58. [PMID: 25054271 DOI: 10.1517/17460441.2014.941352] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Type 2 diabetes mellitus (T2DM) is a chronic, complex and multifactorial metabolic disorder, which has become a serious global health problem. The side effects of known drugs and the deficiency of long-term safety data, in addition to the already determined adverse effects for the current preclinical drugs against T2DM, have largely called upon the urgent exploration of novel therapeutic and preventative strategies against this disease. AREAS COVERED The authors highlight the potential approaches for anti-T2DM drug discovery by focusing on: the restoration of pancreatic β-cell mass, the promotion of insulin secretion, the regulation of oxidative stress and endoplasmic reticulum (ER) stress and the modulation of autophagy. EXPERT OPINION T2DM is based on the gradual development of insulin resistance and β-cell dysfunction. Thus, the restoration of β-cell function is considered as one of the promising therapeutic strategies against T2DM. The stress factors, such as oxidative stress, ER stress and autophagy, play potent roles in the regulation of β-cell apoptosis, insulin secretion and sensitivity in the development of T2DM involving complicated cross-talks. Based on multiplex stress-involved regulatory networks, more and more novel potential targets have been discovered and the multi-targeted drug leads are expected to help develop more effective clinical agents for the treatment of T2DM.
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Affiliation(s)
- Xing Xu
- Shanghai Institute of Materia Medica, Key Laboratory of Receptor Research, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203 , China ; ;
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167
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Mezza T, Kulkarni RN. The regulation of pre- and post-maturational plasticity of mammalian islet cell mass. Diabetologia 2014; 57:1291-303. [PMID: 24824733 DOI: 10.1007/s00125-014-3251-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 03/24/2014] [Indexed: 12/17/2022]
Abstract
Regeneration of mature cells that produce functional insulin represents a major focus and a challenge of current diabetes research aimed at restoring beta cell mass in patients with most forms of diabetes, as well as in ageing. The capacity to adapt to diverse physiological states during life and the consequent ability to cope with increased metabolic demands in the normal regulation of glucose homeostasis is a distinctive feature of the endocrine pancreas in mammals. Both beta and alpha cells, and presumably other islet cells, are dynamically regulated via nutrient, neural and/or hormonal activation of growth factor signalling and the post-transcriptional modification of a variety of genes or via the microbiome to continually maintain a balance between regeneration (e.g. proliferation, neogenesis) and apoptosis. Here we review key regulators that determine islet cell mass at different ages in mammals. Understanding the chronobiology and the dynamics and age-dependent processes that regulate the relationship between the different cell types in the overall maintenance of an optimally functional islet cell mass could provide important insights into planning therapeutic approaches to counter and/or prevent the development of diabetes.
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Affiliation(s)
- Teresa Mezza
- Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, 1 Joslin Place, Boston, MA, 02215, USA
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168
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Patel MS, Srinivasan M, Strutt B, Mahmood S, Hill DJ. Featured Article: Beta cell specific pyruvate dehydrogenase alpha gene deletion results in a reduced islet number and β-cell mass postnatally. Exp Biol Med (Maywood) 2014; 239:975-985. [PMID: 24845368 DOI: 10.1177/1535370214531895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The ability of pancreatic β-cells to undertake glucose-stimulated insulin secretion (GSIS) depends on the generation of adenosine triphosphate (ATP) within the mitochondria from pyruvate, a major rate-limiting enzyme being pyruvate dehydrogenase (PDH) complex (PDC). However, glucose metabolism also controls β-cell mass. To examine the role of PDC in the regulation of pancreatic β-cell development and maturation, we generated β-cell-targeted PDHα subunit knock-out male mice (β-PDHKO) and compared these with control males (β-PDHCT) from birth until 6-8 weeks age. Pancreas morphology, transcription factor expression, pancreatic insulin content, and circulating glucose and insulin values were compared. Compared to β-PDHCT male mice, β-PDHKO animals had significantly reduced pancreatic insulin content from birth, a lower serum insulin content from day 15, and relative hyperglycemia from day 30. Isolated islets from β-PDHKO mice demonstrated a reduced GSIS. The number of islets per pancreatic area, mean islet area, and the proportion of islet cells that were β-cells were all reduced in β-PDHKO animals. Similarly the number of insulin-immunopositive, extra-islet small endocrine cell clusters, a possible source of β-cell progenitors, was lower in β-PDHKO mice. Analysis of pancreatic expression of transcription factors responsible for β-cell lineage commitment, proliferation, and maturation, Pdx1, Neurogenin3, and NeuroD1 showed that mRNA abundance was reduced in the β-PDHKO. This demonstrates that PDC is not only required for insulin expression and glucose-stimulated secretion, but also directly influences β-cell growth and maturity, and positions glucose metabolism as a direct regulator of β-cell mass and plasticity.
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Affiliation(s)
- Mulchand S Patel
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo 14214, NY
| | - Malathi Srinivasan
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo 14214, NY
| | - Brenda Strutt
- Lawson Research Institute, St. Joseph's Health Centre, London, Ontario N6A 4V2, Canada
| | - Saleh Mahmood
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo 14214, NY
| | - David J Hill
- Lawson Research Institute, St. Joseph's Health Centre, London, Ontario N6A 4V2, Canada Department of Medicine, Physiology, and Paediatrics, University of Western Ontario, London, Ontario N6A 3K7, Canada
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169
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Abstract
Because obesity rates have increased dramatically over the past 3 decades, type 2 diabetes has become increasingly prevalent as well. Type 2 diabetes is associated with decreased pancreatic β-cell mass and function, resulting in inadequate insulin production. Conversely, in nondiabetic obesity, an expansion in β-cell mass occurs to provide sufficient insulin and to prevent hyperglycemia. This expansion is at least in part due to β-cell proliferation. This review focuses on the mechanisms regulating obesity-induced β-cell proliferation in humans and mice. Many factors have potential roles in the regulation of obesity-driven β-cell proliferation, including nutrients, insulin, incretins, hepatocyte growth factor, and recently identified liver-derived secreted factors. Much is still unknown about the regulation of β-cell replication, especially in humans. The extracellular signals that activate proliferative pathways in obesity, the relative importance of each of these pathways, and the extent of cross-talk between these pathways are important areas of future study.
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Affiliation(s)
| | - Mieke Baan
- Division of Endocrinology, Department of Medicine, and,School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI; and
| | - Dawn Belt Davis
- Division of Endocrinology, Department of Medicine, and William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin
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170
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Wang Z, York NW, Nichols CG, Remedi MS. Pancreatic β cell dedifferentiation in diabetes and redifferentiation following insulin therapy. Cell Metab 2014; 19:872-82. [PMID: 24746806 PMCID: PMC4067979 DOI: 10.1016/j.cmet.2014.03.010] [Citation(s) in RCA: 300] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/06/2014] [Accepted: 02/26/2014] [Indexed: 01/09/2023]
Abstract
Diabetes is characterized by "glucotoxic" loss of pancreatic β cell function and insulin content, but underlying mechanisms remain unclear. A mouse model of insulin-secretory deficiency induced by β cell inexcitability (K(ATP) gain of function) demonstrates development of diabetes and reiterates the features of human neonatal diabetes. In the diabetic state, β cells lose their mature identity and dedifferentiate to neurogenin3-positive and insulin-negative cells. Lineage-tracing experiments show that dedifferentiated cells can subsequently redifferentiate to mature neurogenin3-negative, insulin-positive β cells after lowering of blood glucose by insulin therapy. We demonstrate here that β cell dedifferentiation, rather than apoptosis, is the main mechanism of loss of insulin-positive cells, and redifferentiation accounts for restoration of insulin content and antidiabetic drug responsivity in these animals. These results may help explain gradual decrease in β cell mass in long-standing diabetes and recovery of β cell function and drug responsivity in type 2 diabetic patients following insulin therapy, and they suggest an approach to rescuing "exhausted" β cells in diabetes.
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Affiliation(s)
- Zhiyu Wang
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Nathaniel W York
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Maria S Remedi
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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171
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Abstract
PURPOSE OF REVIEW Therapies that increase functional β-cell mass may be the best long-term treatment for diabetes. Significant resources are devoted toward this goal, and progress is occurring at a rapid pace. Here, we summarize recent advances relevant to human β-cell regeneration. RECENT FINDINGS New β-cells arise from proliferation of pre-existing β-cells or transdifferentiation from other cell types. In addition, dedifferentiated β-cells may populate islets in diabetes, possibly representing a pool of cells that could redifferentiate into functional β-cells. Advances in finding strategies to drive β-cell proliferation include new insight into proproliferative factors, both circulating and local, and elements intrinsic to the β-cell, such as cell cycle machinery and regulation of gene expression through epigenetic modification and noncoding RNAs. Controversy continues in the arena of generation of β-cells by transdifferentiation from exocrine, ductal, and alpha cells, with studies producing both supporting and opposing data. Progress has been made in redifferentiation of β-cells that have lost expression of β-cell markers. SUMMARY Although significant progress has been made, and promising avenues exist, more work is needed to achieve the goal of β-cell regeneration as a treatment for diabetes.
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Affiliation(s)
- Agata Jurczyk
- University of Massachusetts Medical School, Diabetes Center of Excellence, Worcester, Massachusetts, USA
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172
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Nichols RJ, New C, Annes JP. Adult tissue sources for new β cells. Transl Res 2014; 163:418-31. [PMID: 24345765 PMCID: PMC3976738 DOI: 10.1016/j.trsl.2013.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 11/04/2013] [Accepted: 11/20/2013] [Indexed: 12/25/2022]
Abstract
The diabetes pandemic incurs extraordinary public health and financial costs that are projected to expand for the foreseeable future. Consequently, the development of definitive therapies for diabetes is a priority. Currently, a wide spectrum of therapeutic strategies-from implantable insulin delivery devices to transplantation-based cell replacement therapy, to β-cell regeneration-focus on replacing the lost insulin-producing capacity of individuals with diabetes. Among these, β-cell regeneration remains promising but heretofore unproved. Indeed, recent experimental work has uncovered surprising biology that underscores the potential therapeutic benefit of β-cell regeneration. These studies have elucidated a variety of sources for the endogenous production of new β cells from existing cells. First, β cells, long thought to be postmitotic, have demonstrated the potential for regenerative capacity. Second, the presence of pancreatic facultative endocrine progenitor cells has been established. Third, the malleability of cellular identity has availed the possibility of generating β cells from other differentiated cell types. Here, we review the exciting developments surrounding endogenous sources of β-cell production and consider the potential of realizing a regenerative therapy for diabetes from adult tissues.
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Affiliation(s)
| | - Connie New
- Department of Medicine, Stanford University Medical School, Stanford, Calif
| | - Justin P Annes
- Department of Medicine, Stanford University Medical School, Stanford, Calif.
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173
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Jiao Y, Le Lay J, Yu M, Naji A, Kaestner KH. Elevated mouse hepatic betatrophin expression does not increase human β-cell replication in the transplant setting. Diabetes 2014; 63:1283-8. [PMID: 24353178 PMCID: PMC3964501 DOI: 10.2337/db13-1435] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The recent discovery of betatrophin, a protein secreted by the liver and white adipose tissue in conditions of insulin resistance and shown to dramatically stimulate replication of mouse insulin-producing β-cells, has raised high hopes for the rapid development of a novel therapeutic approach for the treatment of diabetes. At present, however, the effects of betatrophin on human β-cells are not known. Here we use administration of the insulin receptor antagonist S961, shown to increase betatrophin gene expression and stimulate β-cell replication in mice, to test its effect on human β-cells. Although mouse β-cells, in their normal location in the pancreas or when transplanted under the kidney capsule, respond with a dramatic increase in β-cell DNA replication, human β-cells are completely unresponsive. These results put into question whether betatrophin can be developed as a therapeutic approach for treating human diabetes.
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Affiliation(s)
- Yang Jiao
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - John Le Lay
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Ming Yu
- Department of Surgery and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Ali Naji
- Department of Surgery and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Klaus H. Kaestner
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
- Corresponding author: Klaus H. Kaestner,
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174
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Li M, Maddison LA, Page-McCaw P, Chen W. Overnutrition induces β-cell differentiation through prolonged activation of β-cells in zebrafish larvae. Am J Physiol Endocrinol Metab 2014; 306:E799-807. [PMID: 24473439 PMCID: PMC3962607 DOI: 10.1152/ajpendo.00686.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Insulin from islet β-cells maintains glucose homeostasis by stimulating peripheral tissues to remove glucose from circulation. Persistent elevation of insulin demand increases β-cell number through self-replication or differentiation (neogenesis) as part of a compensatory response. However, it is not well understood how a persistent increase in insulin demand is detected. We have previously demonstrated that a persistent increase in insulin demand by overnutrition induces compensatory β-cell differentiation in zebrafish. Here, we use a series of pharmacological and genetic analyses to show that prolonged stimulation of existing β-cells is necessary and sufficient for this compensatory response. In the absence of feeding, tonic, but not intermittent, pharmacological activation of β-cell secretion was sufficient to induce β-cell differentiation. Conversely, drugs that block β-cell secretion, including an ATP-sensitive potassium (K ATP) channel agonist and an L-type Ca(2+) channel blocker, suppressed overnutrition-induced β-cell differentiation. Genetic experiments specifically targeting β-cells confirm existing β-cells as the overnutrition sensor. First, inducible expression of a constitutively active K ATP channel in β-cells suppressed the overnutrition effect. Second, inducible expression of a dominant-negative K ATP mutant induced β-cell differentiation independent of nutrients. Third, sensitizing β-cell metabolism by transgenic expression of a hyperactive glucokinase potentiated differentiation. Finally, ablation of the existing β-cells abolished the differentiation response. Taken together, these data establish that overnutrition induces β-cell differentiation in larval zebrafish through prolonged activation of β-cells. These findings demonstrate an essential role for existing β-cells in sensing overnutrition and compensating for their own insufficiency by recruiting additional β-cells.
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Affiliation(s)
- Mingyu Li
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
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175
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Brissova M, Aamodt K, Brahmachary P, Prasad N, Hong JY, Dai C, Mellati M, Shostak A, Poffenberger G, Aramandla R, Levy SE, Powers AC. Islet microenvironment, modulated by vascular endothelial growth factor-A signaling, promotes β cell regeneration. Cell Metab 2014; 19:498-511. [PMID: 24561261 PMCID: PMC4012856 DOI: 10.1016/j.cmet.2014.02.001] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 03/05/2013] [Accepted: 01/27/2014] [Indexed: 12/31/2022]
Abstract
Pancreatic islet endocrine cell and endothelial cell (EC) interactions mediated by vascular endothelial growth factor-A (VEGF-A) signaling are important for islet differentiation and the formation of highly vascularized islets. To dissect how VEGF-A signaling modulates intra-islet vasculature, islet microenvironment, and β cell mass, we transiently increased VEGF-A production by β cells. VEGF-A induction dramatically increased the number of intra-islet ECs but led to β cell loss. After withdrawal of the VEGF-A stimulus, β cell mass, function, and islet structure normalized as a result of a robust, but transient, burst in proliferation of pre-existing β cells. Bone marrow-derived macrophages (MΦs) recruited to the site of β cell injury were crucial for the β cell proliferation, which was independent of pancreatic location and circulating factors such as glucose. Identification of the signals responsible for the proliferation of adult, terminally differentiated β cells will improve strategies aimed at β cell regeneration and expansion.
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Affiliation(s)
- Marcela Brissova
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| | - Kristie Aamodt
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Priyanka Brahmachary
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Nripesh Prasad
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA; Department of Biology, University of Alabama, Huntsville, Huntsville, AL 35899, USA
| | - Ji-Young Hong
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Chunhua Dai
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Mahnaz Mellati
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alena Shostak
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Greg Poffenberger
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Radhika Aramandla
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Shawn E Levy
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Alvin C Powers
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; VA Tennessee Valley Healthcare System, Nashville, TN 37212, USA.
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176
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Bernal-Mizrachi E, Kulkarni RN, Scott DK, Mauvais-Jarvis F, Stewart AF, Garcia-Ocaña A. Human β-cell proliferation and intracellular signaling part 2: still driving in the dark without a road map. Diabetes 2014; 63:819-31. [PMID: 24556859 PMCID: PMC3931400 DOI: 10.2337/db13-1146] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Enhancing β-cell proliferation is a major goal for type 1 and type 2 diabetes research. Unraveling the network of β-cell intracellular signaling pathways that promote β-cell replication can provide the tools to address this important task. In a previous Perspectives in Diabetes article, we discussed what was known regarding several important intracellular signaling pathways in rodent β-cells, including the insulin receptor substrate/phosphatidylinositol-3 kinase/Akt (IRS-PI3K-Akt) pathways, glycogen synthase kinase-3 (GSK3) and mammalian target of rapamycin (mTOR) S6 kinase pathways, protein kinase Cζ (PKCζ) pathways, and their downstream cell-cycle molecular targets, and contrasted that ample knowledge to the small amount of complementary data on human β-cell intracellular signaling pathways. In this Perspectives, we summarize additional important information on signaling pathways activated by nutrients, such as glucose; growth factors, such as epidermal growth factor, platelet-derived growth factor, and Wnt; and hormones, such as leptin, estrogen, and progesterone, that are linked to rodent and human β-cell proliferation. With these two Perspectives, we attempt to construct a brief summary of knowledge for β-cell researchers on mitogenic signaling pathways and to emphasize how little is known regarding intracellular events linked to human β-cell replication. This is a critical aspect in the long-term goal of expanding human β-cells for the prevention and/or cure of type 1 and type 2 diabetes.
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Affiliation(s)
- Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, and U.S. Department of Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI
- Corresponding authors: Ernesto Bernal-Mizrachi, , and Adolfo Garcia-Ocaña,
| | - Rohit N. Kulkarni
- Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, Harvard Medical School, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
| | - Donald K. Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Franck Mauvais-Jarvis
- Division of Endocrinology and Metabolism, Tulane University School of Medicine and Health Sciences Center, New Orleans, LA
| | - Andrew F. Stewart
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Adolfo Garcia-Ocaña
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY
- Corresponding authors: Ernesto Bernal-Mizrachi, , and Adolfo Garcia-Ocaña,
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177
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Martens GA, Motté E, Kramer G, Stangé G, Gaarn LW, Hellemans K, Nielsen JH, Aerts JM, Ling Z, Pipeleers D. Functional characteristics of neonatal rat β cells with distinct markers. J Mol Endocrinol 2014; 52:11-28. [PMID: 24049066 DOI: 10.1530/jme-13-0106] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Neonatal β cells are considered developmentally immature and hence less glucose responsive. To study the acquisition of mature glucose responsiveness, we compared glucose-regulated redox state, insulin synthesis, and secretion of β cells purified from neonatal or 10-week-old rats with their transcriptomes and proteomes measured by oligonucleotide and LC-MS/MS profiling. Lower glucose responsiveness of neonatal β cells was explained by two distinct properties: higher activity at low glucose and lower activity at high glucose. Basal hyperactivity was associated with higher NAD(P)H, a higher fraction of neonatal β cells actively incorporating (3)H-tyrosine, and persistently increased insulin secretion below 5 mM glucose. Neonatal β cells lacked the steep glucose-responsive NAD(P)H rise between 5 and 10 mM glucose characteristic for adult β cells and accumulated less NAD(P)H at high glucose. They had twofold lower expression of malate/aspartate-NADH shuttle and most glycolytic enzymes. Genome-wide profiling situated neonatal β cells at a developmental crossroad: they showed advanced endocrine differentiation when specifically analyzed for their mRNA/protein level of classical neuroendocrine markers. On the other hand, discrete neonatal β cell subpopulations still expressed mRNAs/proteins typical for developing/proliferating tissues. One example, delta-like 1 homolog (DLK1) was used to investigate whether neonatal β cells with basal hyperactivity corresponded to a more immature subset with high DLK1, but no association was found. In conclusion, the current study supports the importance of glycolytic NADH-shuttling in stimulus function coupling, presents basal hyperactivity as novel property of neonatal β cells, and provides potential markers to recognize intercellular developmental differences in the endocrine pancreas.
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Affiliation(s)
- G A Martens
- Diabetes Research Center, Brussels Free University (VUB), Laarbeeklaan 103, B1090 Brussel, Belgium Department of Clinical Chemistry and Radioimmunology, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, B1090 Brussels, Belgium Department of Medical Biochemistry, Academisch Medisch Centrum, Amsterdam, The Netherlands Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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178
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Hija A, Salpeter S, Klochendler A, Grimsby J, Brandeis M, Glaser B, Dor Y. G0-G1 transition and the restriction point in pancreatic β-cells in vivo. Diabetes 2014; 63:578-84. [PMID: 24130333 PMCID: PMC3900543 DOI: 10.2337/db12-1035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Most of our knowledge on cell kinetics stems from in vitro studies of continuously dividing cells. In this study, we determine in vivo cell-cycle parameters of pancreatic β-cells, a largely quiescent population, using drugs that mimic or prevent glucose-induced replication of β-cells in mice. Quiescent β-cells exposed to a mitogenic glucose stimulation require 8 h to enter the G1 phase of the cell cycle, and this time is prolonged in older age. The duration of G1, S, and G2/M is ~5, 8, and 6 h, respectively. We further provide the first in vivo demonstration of the restriction point at the G0-G1 transition, discovered by Arthur Pardee 40 years ago. The findings may have pharmacodynamic implications in the design of regenerative therapies aimed at increasing β-cell replication and mass in patients with diabetes.
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Affiliation(s)
- Ayat Hija
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Seth Salpeter
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Agnes Klochendler
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Joseph Grimsby
- Department of Metabolic Diseases, Hoffmann-La Roche, Nutley, NJ
| | - Michael Brandeis
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Benjamin Glaser
- Endocrinology and Metabolism Service, Department of Internal Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Yuval Dor
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, Israel
- Corresponding author: Yuval Dor,
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179
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Impact of high-fat feeding on basic helix-loop-helix transcription factors controlling enteroendocrine cell differentiation. Int J Obes (Lond) 2014; 38:1440-8. [PMID: 24480860 DOI: 10.1038/ijo.2014.20] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/03/2013] [Accepted: 01/17/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND OBJECTIVES Gut hormones secreted by enteroendocrine cells (EECs) play a major role in energy regulation. Differentiation of EEC is controlled by the expression of basic helix-loop-helix (bHLH) transcription factors. High-fat (HF) feeding alters gut hormone levels; however, the impact of HF feeding on bHLH transcription factors in mediating EEC differentiation and subsequent gut hormone secretion and expression is not known. METHODS Outbred Sprague-Dawley rats were maintained on chow or HF diet for 12 weeks. Gene and protein expression of intestinal bHLH transcription factors, combined with immunofluorescence studies, were analyzed for both groups in the small intestine and colon. Gut permeability, intestinal lipid and carbohydrate transporters as well as circulating levels and intestinal protein expression of gut peptides were determined. RESULTS We showed that HF feeding resulted in hyperphagia and increased adiposity. HF-fed animals exhibited decreased expression of bHLH transcription factors controlling EEC differentiation (MATH1, NGN3, NEUROD1) and increased expression of bHLH factors modulating enterocyte expression. Furthermore, HF-fed animals had decreased number of total EECs and L-cells. This was accompanied by increased gut permeability and expression of lipid and carbohydrate transporters, and a decrease in circulating and intestinal gut hormone levels. CONCLUSIONS Taken together, our results demonstrate that HF feeding caused decreased secretory lineage (that is, EECs) differentiation through downregulation of bHLH transcription factors, resulting in reduced EEC number and gut hormone levels. Thus, impaired EEC differentiation pathways by HF feeding may promote hyperphagia and subsequent obesity.
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180
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Assefa Z, Lavens A, Steyaert C, Stangé G, Martens GA, Ling Z, Hellemans K, Pipeleers D. Glucose regulates rat beta cell number through age-dependent effects on beta cell survival and proliferation. PLoS One 2014; 9:e85174. [PMID: 24416358 PMCID: PMC3887027 DOI: 10.1371/journal.pone.0085174] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 11/24/2013] [Indexed: 11/22/2022] Open
Abstract
Background Glucose effects on beta cell survival and DNA-synthesis suggest a role as regulator of beta cell mass but data on beta cell numbers are lacking. We examined outcome of these influences on the number of beta cells isolated at different growth stages in their population. Methods Beta cells from neonatal, young-adult and old rats were cultured serum-free for 15 days. Their number was counted by automated whole-well imaging distinguishing influences on cell survival and on proliferative activity. Results Elevated glucose (10–20 versus 5 mmol/l) increased the number of living beta cells from 8-week rats to 30%, following a time- and concentration-dependent recruitment of quiescent cells into DNA-synthesis; a glucokinase-activator lowered the threshold but did not raise total numbers of glucose-recruitable cells. No glucose-induced increase occurred in beta cells from 40-week rats. Neonatal beta cells doubled in number at 5 mmol/l involving a larger activated fraction that did not increase at higher concentrations; however, their higher susceptibility to glucose toxicity at 20 mmol/l resulted in 20% lower living cell numbers than at start. None of the age groups exhibited a repetitively proliferating subpopulation. Conclusions Chronically elevated glucose levels increased the number of beta cells from young-adult but not from old rats; they interfered with expansion of neonatal beta cells and reduced their number. These effects are attributed to age-dependent differences in basal and glucose-induced proliferative activity and in cellular susceptibility to glucose toxicity. They also reflect age-dependent variations in the functional heterogeneity of the rat beta cell population.
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Affiliation(s)
- Zerihun Assefa
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Astrid Lavens
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Christophe Steyaert
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Geert Stangé
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Geert A Martens
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Zhidong Ling
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Karine Hellemans
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
| | - Daniel Pipeleers
- Diabetes Pathology and Therapy Unit, Diabetes Research Center and Center for Beta Cell Therapy, Brussels Free University-VUB, Brussels, Belgium
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181
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Type 2 diabetes and congenital hyperinsulinism cause DNA double-strand breaks and p53 activity in β cells. Cell Metab 2014; 19:109-21. [PMID: 24332968 DOI: 10.1016/j.cmet.2013.11.007] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 03/30/2013] [Accepted: 11/06/2013] [Indexed: 01/09/2023]
Abstract
β cell failure in type 2 diabetes (T2D) is associated with hyperglycemia, but the mechanisms are not fully understood. Congenital hyperinsulinism caused by glucokinase mutations (GCK-CHI) is associated with β cell replication and apoptosis. Here, we show that genetic activation of β cell glucokinase, initially triggering replication, causes apoptosis associated with DNA double-strand breaks and activation of the tumor suppressor p53. ATP-sensitive potassium channels (KATP channels) and calcineurin mediate this toxic effect. Toxicity of long-term glucokinase overactivity was confirmed by finding late-onset diabetes in older members of a GCK-CHI family. Glucagon-like peptide-1 (GLP-1) mimetic treatment or p53 deletion rescues β cells from glucokinase-induced death, but only GLP-1 analog rescues β cell function. DNA damage and p53 activity in T2D suggest shared mechanisms of β cell failure in hyperglycemia and CHI. Our results reveal membrane depolarization via KATP channels, calcineurin signaling, DNA breaks, and p53 as determinants of β cell glucotoxicity and suggest pharmacological approaches to enhance β cell survival in diabetes.
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182
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Role of the mammalian target of rapamycin (mTOR) complexes in pancreatic β-cell mass regulation. VITAMINS AND HORMONES 2014; 95:425-69. [PMID: 24559928 DOI: 10.1016/b978-0-12-800174-5.00017-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Exquisite regulation of insulin secretion by pancreatic β-cells is essential to maintain metabolic homeostasis. β-Cell mass must be accordingly adapted to metabolic needs and can be largely modified under different situations. The mammalian target of rapamycin (mTOR) complexes has been consistently identified as key modulators of β-cell mass. mTOR can be found into two different complexes, mTORC1 and mTORC2. Under systemic insulin resistance, mTORC1/mTORC2 signaling in β-cells is needed to increase β-cell mass and insulin secretion. However, type 2 diabetes arises when these compensatory mechanisms fail, being the role of mTOR complexes still obscure in β-cell failure. In this chapter, we introduce the protein composition and regulation of mTOR complexes and their role in pancreatic β-cells. Furthermore, we describe their main signaling effectors through the review of numerous animal models, which indicate the essential role of mTORC1/mTORC2 in pancreatic β-cell mass regulation.
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183
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Abstract
Regenerative therapy in diabetes with the capacity to reconstitute a functional β-cell mass sufficient for glycemic control holds the promise to effectively prevent the development of devastating late complications due to the unique ability of the β-cell to sense and regulate blood-glucose levels. An ability that cannot be mimicked by insulin replacement therapy or any other means of current treatment regiments for very large patient populations. Recently, Douglas A. Melton's group from Harvard University reported the identification of a circulating protein secreted from the liver under insulin resistant states which is sufficient to dramatically and specifically increase the replication rate of β-cells in the mouse resulting in an increased functional β-cell mass over time. They re-named the factor betatrophin and described a number of exciting features of this molecule which suggested that it could be a potential candidate for development as a regenerative medicine in diabetes. The official name of the gene encoding mouse betatrophin is Gm6484, but it has been annotated a number of times under different names: EG624219, RIFL, Lipasin and ANGPTL8. The official human gene name is C19orf80, but it has also been annotated as TD26, LOC55908, as well as RIFL, Lipasin, ANGPTL8 and betatrophin.
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Affiliation(s)
| | - Ole D Madsen
- Correspondence to: Jonas Ahnfelt-Rønne, and Ole D Madsen,
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184
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Andersson O. Role of adenosine signalling and metabolism in β-cell regeneration. Exp Cell Res 2013; 321:3-10. [PMID: 24315942 DOI: 10.1016/j.yexcr.2013.11.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 11/22/2013] [Accepted: 11/23/2013] [Indexed: 01/09/2023]
Abstract
Glucose homeostasis, which is controlled by the endocrine cells of the pancreas, is disrupted in both type I and type II diabetes. Deficiency in the number of insulin-producing β cells - a primary cause of type I diabetes and a secondary contributor of type II diabetes - leads to hyperglycemia and hence an increase in the need for insulin. Although diabetes can be controlled with insulin injections, a curative approach is needed. A potential approach to curing diabetes involves regenerating the β-cell mass, e.g. by increasing β-cell proliferation, survival, neogenesis or transdifferentiation. The nucleoside adenosine and its cognate nucleotide ATP have long been known to affect insulin secretion, but have more recently been shown to increase β-cell proliferation during homeostatic control and regeneration of the β-cell mass. Adenosine is also known to have anti-inflammatory properties, and agonism of adenosine receptors can promote the survival of β-cells in an inflammatory microenvironment. In this review, both intracellular and extracellular mechanisms of adenosine and ATP are discussed in terms of their established and putative effects on β-cell regeneration.
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Affiliation(s)
- Olov Andersson
- Department of Cell and Molecular Biology, Karolinska Institutet, von Eulers väg 3, 17177 Stockholm, Sweden.
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185
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Cavelti-Weder C, Shtessel M, Reuss JE, Jermendy A, Yamada T, Caballero F, Bonner-Weir S, Weir GC. Pancreatic duct ligation after almost complete β-cell loss: exocrine regeneration but no evidence of β-cell regeneration. Endocrinology 2013; 154:4493-502. [PMID: 24029238 PMCID: PMC3836076 DOI: 10.1210/en.2013-1463] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
There has been great interest in the extent of β-cell regeneration after pancreatic duct ligation (PDL) and whether α- to β-cell conversion might account for β-cell regeneration after near-complete β-cell loss. To assess these questions, we established a PDL-model in adult male rats after almost complete beta-cell depletion achieved by giving a single high dose of streptozocin (STZ) in the fasted state. Because of the resultant severe diabetes, rats were given islet cell transplants to allow long-term follow-up. Although animals were followed up to 10 months, there was no meaningful β-cell regeneration, be it through replication, neogenesis, or α- to β-cell conversion. In contrast, the acinar cell compartment underwent massive changes with first severe acinar degeneration upon PDL injury followed by the appearance of pancreatic adipocytes, and finally near-complete reappearance of acini. We conclude that β-cells and acinar cells, although originating from the same precursors during development, have very distinct regenerative potentials in our PDL model in adult rats.
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Affiliation(s)
- Claudia Cavelti-Weder
- Section on Islet Cell and Regenerative Biology, Research Division, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, One Joslin Place, Boston, Massachusetts 02215.
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186
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Jiao Y, Rieck S, Le Lay J, Kaestner KH. CISH has no non-redundant functions in glucose homeostasis or beta cell proliferation during pregnancy in mice. Diabetologia 2013; 56:2435-45. [PMID: 23949579 PMCID: PMC3816496 DOI: 10.1007/s00125-013-3014-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 07/16/2013] [Indexed: 10/26/2022]
Abstract
AIMS/HYPOTHESIS Increased beta cell proliferation during pregnancy is mediated by the Janus kinase 2/signal transducer and activator of transcription 5 (JAK2/STAT5) signalling pathway in response to increased lactogen levels. Activation of the pathway leads to transcriptional upregulation of Cish (encoding cytokine-inducible SH2 domain-containing protein), a member of the suppressor of cytokine signalling (SOCS) family of genes, forming a negative-feedback loop. Here, we examined whether conditional gene ablation of Cish in the pancreas improves beta cell proliferation and beta cell function during pregnancy in mice. METHODS We derived mice with a novel, conditional loxP allele for Cish. Pancreas-specific ablation of Cish was achieved by crossing Cish (loxP/loxP) mice with Pdx1-Cre (Early) mice. Beta cell proliferation was quantified by BrdU labelling. Glucose homeostasis was examined with glucose tolerance tests and determination of plasma insulin levels. The expression of other Socs genes and target genes of p-STAT5 related to beta cell function and beta cell proliferation was determined by quantitative PCR. RESULTS There was no difference in beta cell proliferation or glucose homeostasis between the Cish mutant group and the control group. The p-STAT5 protein level was the same in Cish mutant and control mice. Socs2 gene expression was higher in Cish mutant than control mice at pregnancy day 9.5. The expression of other Socs genes was the same between control and mutant mice. CONCLUSIONS/INTERPRETATION Our results show that CISH has no non-redundant functions in beta cell proliferation or glucose homeostasis during pregnancy in mice. Socs2 might compensate for the loss of Cish during pregnancy.
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Affiliation(s)
- Yang Jiao
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Sebastian Rieck
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - John Le Lay
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Klaus H. Kaestner
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- 12-126 Smilow Center for Translational Research, 3400 Civic Center Blvd Bldg 421, Philadelphia, PA 19104-5156
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187
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Cerf ME. Beta cell dynamics: beta cell replenishment, beta cell compensation and diabetes. Endocrine 2013; 44:303-11. [PMID: 23483434 DOI: 10.1007/s12020-013-9917-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 03/01/2013] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes, characterized by persistent hyperglycemia, arises mostly from beta cell dysfunction and insulin resistance and remains a highly complex metabolic disease due to various stages in its pathogenesis. Glucose homeostasis is primarily regulated by insulin secretion from the beta cells in response to prevailing glycemia. Beta cell populations are dynamic as they respond to fluctuating insulin demand. Beta cell replenishment and death primarily regulate beta cell populations. Beta cells, pancreatic cells, and extra-pancreatic cells represent the three tiers for replenishing beta cells. In rodents, beta cell self-replenishment appears to be the dominant source for new beta cells supported by pancreatic cells (non-beta islet cells, acinar cells, and duct cells) and extra-pancreatic cells (liver, neural, and stem/progenitor cells). In humans, beta cell neogenesis from non-beta cells appears to be the dominant source of beta cell replenishment as limited beta cell self-replenishment occurs particularly in adulthood. Metabolic states of increased insulin demand trigger increased insulin synthesis and secretion from beta cells. Beta cells, therefore, adapt to support their physiology. Maintaining physiological beta cell populations is a strategy for targeting metabolic states of persistently increased insulin demand as in diabetes.
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Affiliation(s)
- Marlon E Cerf
- Diabetes Discovery Platform, South African Medical Research, PO Box 19070, Tygerberg, 7505, South Africa,
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188
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Shirakawa J, Togashi Y, Sakamoto E, Kaji M, Tajima K, Orime K, Inoue H, Kubota N, Kadowaki T, Terauchi Y. Glucokinase activation ameliorates ER stress-induced apoptosis in pancreatic β-cells. Diabetes 2013; 62:3448-58. [PMID: 23801577 PMCID: PMC3781485 DOI: 10.2337/db13-0052] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The derangement of endoplasmic reticulum (ER) homeostasis triggers β-cell apoptosis, leading to diabetes. Glucokinase upregulates insulin receptor substrate 2 (IRS-2) expression in β-cells, but the role of glucokinase and IRS-2 in ER stress has been unclear. In this study, we investigated the impact of glucokinase activation by glucokinase activator (GKA) on ER stress in β-cells. GKA administration improved β-cell apoptosis in Akita mice, a model of ER stress-mediated diabetes. GKA increased the expression of IRS-2 in β-cells, even under ER stress. Both glucokinase-deficient Akita mice and IRS-2-deficient Akita mice exhibited an increase in β-cell apoptosis, compared with Akita mice. β-cell-specific IRS-2-overexpressing (βIRS-2-Tg) Akita mice showed less β-cell apoptosis than Akita mice. IRS-2-deficient islets were vulnerable, but βIRS-2-Tg islets were resistant to ER stress-induced apoptosis. Meanwhile, GKA regulated the expressions of C/EBP homologous protein (CHOP) and other ER stress-related genes in an IRS-2-independent fashion in islets. GKA suppressed the expressions of CHOP and Bcl2-associated X protein (Bax) and protected against β-cell apoptosis under ER stress in an ERK1/2-dependent, IRS-2-independent manner. Taken together, GKA ameliorated ER stress-mediated apoptosis by harmonizing IRS-2 upregulation and the IRS-2-independent control of apoptosis in β-cells.
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Affiliation(s)
- Jun Shirakawa
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Yu Togashi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Eri Sakamoto
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Mitsuyo Kaji
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Kazuki Tajima
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Kazuki Orime
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Hideaki Inoue
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Naoto Kubota
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Yasuo Terauchi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Corresponding author: Yasuo Terauchi,
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189
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Guo L, Inada A, Aguayo-Mazzucato C, Hollister-Lock J, Fujitani Y, Weir GC, Wright CV, Sharma A, Bonner-Weir S. PDX1 in ducts is not required for postnatal formation of β-cells but is necessary for their subsequent maturation. Diabetes 2013; 62:3459-68. [PMID: 23775765 PMCID: PMC3781453 DOI: 10.2337/db12-1833] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pancreatic duodenal homeobox-1 (Pdx1), a transcription factor required for pancreatic development and maintenance of β-cell function, was assessed for a possible role in postnatal β-cell formation from progenitors in the pancreatic ducts by selectively deleting Pdx1 from the ducts. Carbonic anhydrase II (CAII)(Cre);Pdx1(Fl) mice were euglycemic for the first 2 postnatal weeks but showed moderate hyperglycemia from 3 to 7 weeks of age. By 10 weeks, they had near-normal morning fed glucose levels but showed severely impaired glucose tolerance and insulin secretion. Yet the loss of Pdx1 did not result in decreased islet and β-cell mass at 4 and 10 weeks of age. Within the same pancreas, there was a mixed population of islets, with PDX1 and MAFA protein expression normal in some cells and severely diminished in others. Even at 10 weeks, islets expressed immaturity markers. Thus, we conclude that Pdx1 is not necessary for the postnatal formation of β-cells but is essential for their full maturation to glucose-responsive β-cells.
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Affiliation(s)
- Lili Guo
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Akari Inada
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
- Diabetes and Genes, Advanced Medical Initiatives, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Cristina Aguayo-Mazzucato
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Jennifer Hollister-Lock
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Yoshio Fujitani
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Gordon C. Weir
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Christopher V.E. Wright
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Arun Sharma
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Susan Bonner-Weir
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
- Corresponding author: Susan Bonner-Weir,
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190
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Taylor BL, Liu FF, Sander M. Nkx6.1 is essential for maintaining the functional state of pancreatic beta cells. Cell Rep 2013; 4:1262-75. [PMID: 24035389 DOI: 10.1016/j.celrep.2013.08.010] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 07/11/2013] [Accepted: 08/05/2013] [Indexed: 02/06/2023] Open
Abstract
Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell failure in diabetes. However, the molecular mechanisms that underlie the loss of beta cell features remain unclear. Here, we identify an Nkx6.1-controlled gene regulatory network as essential for maintaining the functional and molecular traits of mature beta cells. Conditional Nkx6.1 inactivation in adult mice caused rapid-onset diabetes and hypoinsulinemia. Genome-wide analysis of Nkx6.1-regulated genes and functional assays further revealed a critical role for Nkx6.1 in the control of insulin biosynthesis, insulin secretion, and beta cell proliferation. Over time, Nkx6.1-deficient beta cells acquired molecular characteristics of delta cells, revealing a molecular link between impaired beta cell functional properties and loss of cell identity. Given that Nkx6.1 levels are reduced in human type 2 diabetic beta cells, our study lends support to the concept that loss of beta cell features could contribute to the pathogenesis of diabetes.
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Affiliation(s)
- Brandon L Taylor
- Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California, San Diego, La Jolla, CA 92093-0695, USA
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191
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Abstract
In healthy individuals, insulin resistance is associated with physiological conditions such as pregnancy or body weight gain and triggers an increase in beta cell number and insulin secretion capacity to preserve normoglycaemia. Failure of this beta cell compensation capacity is a fundamental cause of diabetic hyperglycaemia. Incomplete understanding of the molecular mechanisms controlling the plasticity of adult beta cells mechanisms and how these cells fail during the pathogenesis of diabetes strongly limits the ability to develop new beta cell-specific therapies. Here, current knowledge of the signalling pathways controlling beta cell plasticity is reviewed, and possible directions for future research are discussed.
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Affiliation(s)
- B Thorens
- Center for Integrative Genomics, University of Lausanne, Switzerland.
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192
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Kumar S, Zou Y, Bao Q, Wang M, Dai G. Proteomic analysis of immediate-early response plasma proteins after 70% and 90% partial hepatectomy. Hepatol Res 2013; 43:876-89. [PMID: 23279269 PMCID: PMC4354878 DOI: 10.1111/hepr.12030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/18/2012] [Accepted: 11/20/2012] [Indexed: 02/08/2023]
Abstract
AIM Partial hepatectomy (PH) induces robust hepatic regenerative and metabolic responses that are considered to be triggered by humoral factors. The aim of the study was to identify plasma protein factors that potentially trigger or reflect the body's immediate-early responses to liver mass reduction. METHODS Male C57BL/6 mice were subjected to sham operation, 70% PH or 90% PH. Blood was collected from the inferior vena cava at 20, 60 and 180 min after surgery. RESULTS Using a label-free quantitative mass spectrometry-based proteomics approach, we identified 399 proteins exhibiting significant changes in plasma expression between any two groups. Of the 399 proteins, 167 proteins had multiple unique sequences and high peptide ID confidence (>90%) and were defined as priority 1 proteins. A group of plasma proteins largely associated with metabolism is enriched after 70% PH. Among the plasma proteins that respond to 90% PH are a dominant group of proteins that are also associated with metabolism and one known cytokine (platelet factor 4). Ninety percent PH and 70% PH induces similar changes in plasma protein profile. CONCLUSION Our findings enable us to gain insight into the immediate-early response of plasma proteins to liver mass loss. Our data support the notion that increased metabolic demands of the body after massive liver mass loss may function as a sensor that calibrates hepatic regenerative response.
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Affiliation(s)
- Sudhanshu Kumar
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
| | - Yuhong Zou
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
| | - Qi Bao
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
| | - Mu Wang
- Department of Biochemistry and Molecular Biology, School of Medicine, Indiana University, Indianapolis, Indiana
| | - Guoli Dai
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
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193
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Salpeter SJ, Khalaileh A, Weinberg-Corem N, Ziv O, Glaser B, Dor Y. Systemic regulation of the age-related decline of pancreatic β-cell replication. Diabetes 2013; 62:2843-8. [PMID: 23630298 PMCID: PMC3717843 DOI: 10.2337/db13-0160] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The frequency of pancreatic β-cell replication declines dramatically with age, potentially contributing to the increased risk of type 2 diabetes in old age. Previous studies have shown the involvement of cell-autonomous factors in this phenomenon, particularly the decline of polycomb genes and accumulation of p16/INK4A. Here, we demonstrate that a systemic factor found in the circulation of young mice is able to increase the proliferation rate of old pancreatic β-cells. Old mice parabiosed to young mice have increased β-cell replication compared with unjoined old mice or old mice parabiosed to old mice. In addition, we demonstrate that old β-cells transplanted into young recipients have increased replication rate compared with cells transplanted into old recipients; conversely, young β-cells transplanted into old mice decrease their replication rate compared with young cells transplanted into young recipients. The expression of p16/INK4A mRNA did not change in heterochronic parabiosis, suggesting the involvement of other pathways. We conclude that systemic factors contribute to the replicative decline of old pancreatic β-cells.
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Affiliation(s)
- Seth J. Salpeter
- Department of Developmental Biology and Cancer Research and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Abed Khalaileh
- Department of Developmental Biology and Cancer Research and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Noa Weinberg-Corem
- Department of Developmental Biology and Cancer Research and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Oren Ziv
- Department of Developmental Biology and Cancer Research and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Benjamin Glaser
- Endocrinology and Metabolism Service, Department of Internal Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Yuval Dor
- Department of Developmental Biology and Cancer Research and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- Corresponding author: Yuval Dor,
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194
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Sabatini PV, Krentz NA, Zarrouki B, Westwell-Roper CY, Nian C, Uy RA, Shapiro AJ, Poitout V, Lynn FC. Npas4 is a novel activity-regulated cytoprotective factor in pancreatic β-cells. Diabetes 2013; 62:2808-20. [PMID: 23656887 PMCID: PMC3717850 DOI: 10.2337/db12-1527] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cellular homeostasis requires intrinsic sensing mechanisms to temper function in the face of prolonged activity. In the pancreatic β-cell, glucose is likely a physiological trigger that activates an adaptive response to stimulation, thereby maintaining cellular homeostasis. Immediate early genes (IEGs) are activated as a first line of defense in cellular homeostasis and are largely responsible for transmitting an environmental cue to a cellular response. Here we examine the regulation and function of the novel β-cell IEG, neuronal PAS domain protein 4 (Npas4). Using MIN6 cells, mouse and human islets, as well as in vivo infusions, we demonstrate that Npas4 is expressed within pancreatic islets and is upregulated by β-cell depolarizing agents. Npas4 tempers β-cell function through a direct inhibitory interaction with the insulin promoter and by blocking the potentiating effects of GLP-1 without significantly reducing glucose-stimulated secretion. Finally, Npas4 expression is induced by classical endoplasmic reticulum (ER) stressors and can prevent thapsigargin- and palmitate-induced dysfunction and cell death. These results suggest that Npas4 is a key activity-dependent regulator that improves β-cell efficiency in the face of stress. We posit that Npas4 could be a novel therapeutic target in type 2 diabetes that could both reduce ER stress and cell death and maintain basal cell function.
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Affiliation(s)
- Paul V. Sabatini
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicole A.J. Krentz
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Bader Zarrouki
- Montreal Diabetes Research Center, CRCHUM, and Department of Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Clara Y. Westwell-Roper
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Cuilan Nian
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ryan A. Uy
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
| | | | - Vincent Poitout
- Montreal Diabetes Research Center, CRCHUM, and Department of Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Francis C. Lynn
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding author: Francis C. Lynn,
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195
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Moreno-Asso A, Castaño C, Grilli A, Novials A, Servitja JM. Glucose regulation of a cell cycle gene module is selectively lost in mouse pancreatic islets during ageing. Diabetologia 2013; 56:1761-72. [PMID: 23685457 DOI: 10.1007/s00125-013-2930-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/12/2013] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS Transcriptional networks in beta cells are modulated by extracellular signals such as glucose, thereby ensuring beta cell adaptation to systemic insulin demands. Ageing is a main risk factor for type 2 diabetes and has been associated with perturbed expression of genes essential for beta cell function. We aimed to uncover glucose-dependent gene modules in mouse pancreatic islets and investigate how this regulation is affected by ageing. METHODS Global gene expression was assessed in pancreatic islets from young and aged wild-type and Cdkn2a (Ink4a/Arf)-deficient mice exposed to different glucose concentrations. Gene modules were identified by gene ontology and gene set enrichment analysis. RESULTS Gene expression profiling revealed that variations in glucose levels have a widespread and highly dynamic impact on the islet transcriptome. Stimulatory glucose levels induced the expression of highly beta cell-selective genes and repressed the expression of ubiquitous genes involved in stress and antiproliferative responses, and in organelle biogenesis. Interestingly, a module comprising cell cycle genes was significantly induced between non-stimulatory and stimulatory glucose concentrations. Unexpectedly, glucose regulation of gene expression was broadly maintained in islets from old mice. However, glucose induction of mitotic genes was selectively lost in aged islets and was not even restored in the absence of the cell cycle inhibitors p16(INK4a) and p19(ARF), which have been implicated in the restricted proliferative capacity of beta cells with advanced age. CONCLUSIONS/INTERPRETATION Glucose-dependent transcriptional networks in islets are globally conserved during ageing, with the exception of the ability of stimulatory glucose levels to induce a cell cycle gene module.
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Affiliation(s)
- A Moreno-Asso
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centre Esther Koplowitz, Barcelona, Spain
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196
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Abstract
Insulin-secreting pancreatic β-cells are essential regulators of mammalian metabolism. The absence of functional β-cells leads to hyperglycemia and diabetes, making patients dependent on exogenously supplied insulin. Recent insights into β-cell development, combined with the discovery of pluripotent stem cells, have led to an unprecedented opportunity to generate new β-cells for transplantation therapy and drug screening. Progress has also been made in converting terminally differentiated cell types into β-cells using transcriptional regulators identified as key players in normal development, and in identifying conditions that induce β-cell replication in vivo and in vitro. Here, we summarize what is currently known about how these strategies could be utilized to generate new β-cells and highlight how further study into the mechanisms governing later stages of differentiation and the acquisition of functional capabilities could inform this effort.
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Affiliation(s)
- Felicia W Pagliuca
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
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197
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Fiaschi-Taesch NM, Kleinberger JW, Salim FG, Troxell R, Wills R, Tanwir M, Casinelli G, Cox AE, Takane KK, Srinivas H, Scott DK, Stewart AF. Cytoplasmic-nuclear trafficking of G1/S cell cycle molecules and adult human β-cell replication: a revised model of human β-cell G1/S control. Diabetes 2013; 62:2460-70. [PMID: 23493571 PMCID: PMC3712040 DOI: 10.2337/db12-0778] [Citation(s) in RCA: 51] [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] [Indexed: 12/14/2022]
Abstract
Harnessing control of human β-cell proliferation has proven frustratingly difficult. Most G1/S control molecules, generally presumed to be nuclear proteins in the human β-cell, are in fact constrained to the cytoplasm. Here, we asked whether G1/S molecules might traffic into and out of the cytoplasmic compartment in association with activation of cell cycle progression. Cdk6 and cyclin D3 were used to drive human β-cell proliferation and promptly translocated into the nucleus in association with proliferation. In contrast, the cell cycle inhibitors p15, p18, and p19 did not alter their location, remaining cytoplasmic. Conversely, p16, p21, and p27 increased their nuclear frequency. In contrast once again, p57 decreased its nuclear frequency. Whereas proliferating β-cells contained nuclear cyclin D3 and cdk6, proliferation generally did not occur in β-cells that contained nuclear cell cycle inhibitors, except p21. Dynamic cytoplasmic-nuclear trafficking of cdk6 was confirmed using green fluorescent protein-tagged cdk6 and live cell imaging. Thus, we provide novel working models describing the control of cell cycle progression in the human β-cell. In addition to known obstacles to β-cell proliferation, cytoplasmic-to-nuclear trafficking of G1/S molecules may represent an obstacle as well as a therapeutic opportunity for human β-cell expansion.
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Affiliation(s)
- Nathalie M Fiaschi-Taesch
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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198
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Abstract
ATP-sensitive K+ (KATP) channels in pancreatic β-cells couple glucose metabolism to insulin secretion. Reduced KATP channel activity produces excessive insulin release and hyperinsulinism whereas increased KATP channel activity leads to lower insulin secretion and diabetes. Paradoxically, mice with genetic deletion of KATP channels, or loss-of-function mutations, are only transiently hypoglycaemic during the neonatal period and often display reduced glucose-stimulated insulin secretion subsequently. Mice with KATP channel gain-of-function mutations are hyperglycaemic and have impaired glucose-stimulated insulin secretion, a phenotype that accurately mimics human diabetes. This review discusses how mice expressing altered KATP channels have provided valuable insight into β-cell function.
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Affiliation(s)
- Melissa F Brereton
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, and OXION Centre for Ion Channel Studies, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Frances M Ashcroft
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, and OXION Centre for Ion Channel Studies, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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199
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Abstract
Previous work in insulinoma cell lines has established that calcineurin plays a critical role in the activation of cAMP-responsive element binding protein (Creb), a key transcription factor required for β-cell function and survival, by dephosphorylating the Creb coactivator Creb-regulated transcription coactivator (Crtc)2 at 2 regulatory sites, Ser171 and Ser275. Here, we report that Crtc2 is essential both for glucose-stimulated insulin secretion and cell survival in the β-cell. Endogenous Crtc2 activation is achieved via increasing glucose levels to the physiological feeding range, indicating that Crtc2 is a sensor that couples ambient glucose concentrations to Creb activity in the β-cell. Immunosuppressant drugs such as cyclosporin A and tacrolimus that target the protein phosphatase calcineurin are commonly administered after organ transplantation. Chronic use is associated with reduced insulin secretion and new onset diabetes, suggestive of pancreatic β-cell dysfunction. Importantly, we show that overexpression of a Crtc2 mutant rendered constitutively active by introduction of nonphosphorylatable alanine residues at Ser171 and Ser275 permits Creb target gene activation under conditions when calcineurin is inhibited. Taken together, these data suggest that promoting Crtc2-Creb activity is required for β-cell function and proliferation and promoting this pathway could ameliorate symptoms of new onset diabetes after transplantation.
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Affiliation(s)
- Chandra E Eberhard
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
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200
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Gupta D, Leahy AA, Monga N, Peshavaria M, Jetton TL, Leahy JL. Peroxisome proliferator-activated receptor γ (PPARγ) and its target genes are downstream effectors of FoxO1 protein in islet β-cells: mechanism of β-cell compensation and failure. J Biol Chem 2013; 288:25440-25449. [PMID: 23788637 DOI: 10.1074/jbc.m113.486852] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The molecular mechanisms and signaling pathways that drive islet β-cell compensation and failure are not fully resolved. We have used in vitro and in vivo systems to show that FoxO1, an integrator of metabolic stimuli, inhibits PPARγ expression in β-cells, thus transcription of its target genes (Pdx1, glucose-dependent insulinotropic polypeptide (GIP) receptor, and pyruvate carboxylase) that are important regulators of β-cell function, survival, and compensation. FoxO1 inhibition of target gene transcription is normally relieved when upstream activation induces its translocation from the nucleus to the cytoplasm. Attesting to the central importance of this pathway, islet expression of PPARγ and its target genes was enhanced in nondiabetic insulin-resistant rats and markedly reduced with diabetes induction. Insight into the impaired PPARγ signaling with hyperglycemia was obtained with confocal microscopy of pancreas sections that showed an intense nuclear FoxO1 immunostaining pattern in the β-cells of diabetic rats in contrast to the nuclear and cytoplasmic FoxO1 in nondiabetic rats. These findings suggest a FoxO1/PPARγ-mediated network acting as a core component of β-cell adaptation to metabolic stress, with failure of this response from impaired FoxO1 activation causing or exacerbating diabetes.
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Affiliation(s)
- Dhananjay Gupta
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Averi A Leahy
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Navjot Monga
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Mina Peshavaria
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Thomas L Jetton
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Jack L Leahy
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405.
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