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Blandino-Rosano M, Louzada RA, Werneck-De-Castro JP, Lubaczeuski C, Almaça J, Rüegg MA, Hall MN, Leibowitz G, Bernal-Mizrachi E. Raptor levels are critical for β-cell adaptation to a high-fat diet in male mice. Mol Metab 2023; 75:101769. [PMID: 37423392 PMCID: PMC10391668 DOI: 10.1016/j.molmet.2023.101769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/19/2023] [Accepted: 06/29/2023] [Indexed: 07/11/2023] Open
Abstract
OBJECTIVE The essential role of raptor/mTORC1 signaling in β-cell survival and insulin processing has been recently demonstrated using raptor knock-out models. Our aim was to evaluate the role of mTORC1 function in adaptation of β-cells to insulin resistant state. METHOD Here, we use mice with heterozygous deletion of raptor in β-cells (βraHet) to assess whether reduced mTORC1 function is critical for β-cell function in normal conditions or during β-cell adaptation to high-fat diet (HFD). RESULTS Deletion of a raptor allele in β-cells showed no differences at the metabolic level, islets morphology, or β-cell function in mice fed regular chow. Surprisingly, deletion of only one allele of raptor increases apoptosis without altering proliferation rate and is sufficient to impair insulin secretion when fed a HFD. This is accompanied by reduced levels of critical β-cell genes like Ins1, MafA, Ucn3, Glut2, Glp1r, and specially PDX1 suggesting an improper β-cell adaptation to HFD. CONCLUSION This study identifies that raptor levels play a key role in maintaining PDX1 levels and β-cell function during the adaptation of β-cell to HFD. Finally, we identified that Raptor levels regulate PDX1 levels and β-cell function during β-cell adaptation to HFD by reduction of the mTORC1-mediated negative feedback and activation of the AKT/FOXA2/PDX1 axis. We suggest that Raptor levels are critical to maintaining PDX1 levels and β-cell function in conditions of insulin resistance in male mice.
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Affiliation(s)
- Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA; Miami VA Health Care System, Miami, FL, USA.
| | - Ruy Andrade Louzada
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Joao Pedro Werneck-De-Castro
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA; Miami VA Health Care System, Miami, FL, USA
| | - Camila Lubaczeuski
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Joana Almaça
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Markus A Rüegg
- Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Gil Leibowitz
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA; Miami VA Health Care System, Miami, FL, USA.
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Louzada RA, Blandino-Rosano M, Flores S, Lubaczeuski C, Cui T, Sha W, Cai R, Schally AV, Bernal-Mizrachi E. GHRH agonist MR-409 protects β-cells from streptozotocin-induced diabetes. Proc Natl Acad Sci U S A 2023; 120:e2209810120. [PMID: 37307472 PMCID: PMC10288557 DOI: 10.1073/pnas.2209810120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 04/17/2023] [Indexed: 06/14/2023] Open
Abstract
Patients with type 1 diabetes (T1D) suffer from insufficient functional β-cell mass, which results from infiltration of inflammatory cells and cytokine-mediated β-cell death. Previous studies demonstrated the beneficial effects of agonists of growth hormone-releasing hormone receptor (GHRH-R), such as MR-409 on preconditioning of islets in a transplantation model. However, the therapeutic potential and protective mechanisms of GHRH-R agonists on models of T1D diabetes have not been explored. Using in vitro and in vivo models of T1D, we assessed the protective propertie of the GHRH agonist, MR409 on β-cells. The treatment of insulinoma cell lines and rodent and human islets with MR-409 induces Akt signaling by induction of insulin receptor substrate 2 (IRS2), a master regulator of survival and growth in β-cells, in a PKA-dependent manner. The increase in cAMP/PKA/CREB/IRS2 axis by MR409 was associated with decrease in β-cell death and improved insulin secretory function in mouse and human islets exposed to proinflammatory cytokines. The assessment of the effects of GHRH agonist MR-409 in a model of T1D induced by low-dose streptozotocin showed that mice treated with MR-409 exhibited better glucose homeostasis, higher insulin levels, and preservation of β-cell mass. Increased IRS2 expression in β-cells in the group treated with MR-409 corroborated the in vitro data and provided evidence for the underlying mechanism responsible for beneficial effects of MR-409 in vivo. Collectively, our data show that MR-409 is a novel therapeutic agent for the prevention and treatment of β-cells death in T1D.
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Affiliation(s)
- Ruy A. Louzada
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL33136
| | - Manuel Blandino-Rosano
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL33136
| | - Sebastian Flores
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL33136
| | - Camila Lubaczeuski
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL33136
| | - Tengjiao Cui
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL33136
- Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL33125
- South Florida Veterans Affairs Foundation for Research and Education, Miami, FL33125
| | - Wei Sha
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL33136
- Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL33125
- South Florida Veterans Affairs Foundation for Research and Education, Miami, FL33125
| | - Renzhi Cai
- Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL33125
- South Florida Veterans Affairs Foundation for Research and Education, Miami, FL33125
| | - Andrew V. Schally
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL33136
- Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL33125
- South Florida Veterans Affairs Foundation for Research and Education, Miami, FL33125
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL33136
- Division of Hematology and Oncology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL33136
- Veterans Affairs Medical Center, Miami, FL33136
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL33136
- Veterans Affairs Medical Center, Miami, FL33136
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3
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Xu W, Qadir MMF, Nasteska D, Mota de Sa P, Gorvin CM, Blandino-Rosano M, Evans CR, Ho T, Potapenko E, Veluthakal R, Ashford FB, Bitsi S, Fan J, Bhondeley M, Song K, Sure VN, Sakamuri SSVP, Schiffer L, Beatty W, Wyatt R, Frigo DE, Liu X, Katakam PV, Arlt W, Buck J, Levin LR, Hu T, Kolls J, Burant CF, Tomas A, Merrins MJ, Thurmond DC, Bernal-Mizrachi E, Hodson DJ, Mauvais-Jarvis F. Architecture of androgen receptor pathways amplifying glucagon-like peptide-1 insulinotropic action in male pancreatic β cells. Cell Rep 2023; 42:112529. [PMID: 37200193 PMCID: PMC10312392 DOI: 10.1016/j.celrep.2023.112529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 12/20/2022] [Accepted: 05/03/2023] [Indexed: 05/20/2023] Open
Abstract
Male mice lacking the androgen receptor (AR) in pancreatic β cells exhibit blunted glucose-stimulated insulin secretion (GSIS), leading to hyperglycemia. Testosterone activates an extranuclear AR in β cells to amplify glucagon-like peptide-1 (GLP-1) insulinotropic action. Here, we examined the architecture of AR targets that regulate GLP-1 insulinotropic action in male β cells. Testosterone cooperates with GLP-1 to enhance cAMP production at the plasma membrane and endosomes via: (1) increased mitochondrial production of CO2, activating the HCO3--sensitive soluble adenylate cyclase; and (2) increased Gαs recruitment to GLP-1 receptor and AR complexes, activating transmembrane adenylate cyclase. Additionally, testosterone enhances GSIS in human islets via a focal adhesion kinase/SRC/phosphatidylinositol 3-kinase/mammalian target of rapamycin complex 2 actin remodeling cascade. We describe the testosterone-stimulated AR interactome, transcriptome, proteome, and metabolome that contribute to these effects. This study identifies AR genomic and non-genomic actions that enhance GLP-1-stimulated insulin exocytosis in male β cells.
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Affiliation(s)
- Weiwei Xu
- Section of Endocrinology and Metabolism, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA
| | - M M Fahd Qadir
- Section of Endocrinology and Metabolism, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA
| | - Daniela Nasteska
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK
| | - Paula Mota de Sa
- Section of Endocrinology and Metabolism, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA
| | - Caroline M Gorvin
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Charles R Evans
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Thuong Ho
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Evgeniy Potapenko
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI, USA
| | - Rajakrishnan Veluthakal
- Department of Molecular and Cellular Endocrinology, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
| | - Fiona B Ashford
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK
| | - Stavroula Bitsi
- Division of Diabetes, Endocrinology & Metabolism, Section of Cell Biology and Functional Genomics, Imperial College London, London SW7 2AZ, UK
| | - Jia Fan
- Center for Cellular and Molecular Diagnostics, Department of Molecular & Cellular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Manika Bhondeley
- Section of Endocrinology and Metabolism, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA
| | - Kejing Song
- Center for Translational Research in Infection and Inflammation, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Venkata N Sure
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Siva S V P Sakamuri
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Lina Schiffer
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK
| | - Wandy Beatty
- Molecular Imaging Facility, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Rachael Wyatt
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK
| | - Daniel E Frigo
- Departments of Cancer Systems Imaging and Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Xiaowen Liu
- Division of Biomedical Informatics and Genomics, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Prasad V Katakam
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Wiebke Arlt
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK; National Institute for Health Research Birmingham Biomedical Research Centre, University Hospitals Birmingham NHS Foundation Trust and University of Birmingham, Birmingham B15 2TH, UK
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10021, USA
| | - Lonny R Levin
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10021, USA
| | - Tony Hu
- Center for Cellular and Molecular Diagnostics, Department of Molecular & Cellular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Jay Kolls
- Center for Translational Research in Infection and Inflammation, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Charles F Burant
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alejandra Tomas
- Division of Diabetes, Endocrinology & Metabolism, Section of Cell Biology and Functional Genomics, Imperial College London, London SW7 2AZ, UK
| | - Matthew J Merrins
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Debbie C Thurmond
- Department of Molecular and Cellular Endocrinology, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - David J Hodson
- Institute of Metabolism and Systems Research and Centre for Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TT, UK
| | - Franck Mauvais-Jarvis
- Section of Endocrinology and Metabolism, John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, USA; Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA; Tulane Center of Excellence in Sex-Based Biology & Medicine, New Orleans, LA 70112, USA.
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4
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Blandino-Rosano M, Scheys JO, Werneck-de-Castro JP, Louzada RA, Almaça J, Leibowitz G, Rüegg MA, Hall MN, Bernal-Mizrachi E. Novel roles of mTORC2 in regulation of insulin secretion by actin filament remodeling. Am J Physiol Endocrinol Metab 2022; 323:E133-E144. [PMID: 35723227 PMCID: PMC9291412 DOI: 10.1152/ajpendo.00076.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mammalian target of rapamycin (mTOR) kinase is an essential hub where nutrients and growth factors converge to control cellular metabolism. mTOR interacts with different accessory proteins to form complexes 1 and 2 (mTORC), and each complex has different intracellular targets. Although mTORC1's role in β-cells has been extensively studied, less is known about mTORC2's function in β-cells. Here, we show that mice with constitutive and inducible β-cell-specific deletion of RICTOR (βRicKO and iβRicKO mice, respectively) are glucose intolerant due to impaired insulin secretion when glucose is injected intraperitoneally. Decreased insulin secretion in βRicKO islets was caused by abnormal actin polymerization. Interestingly, when glucose was administered orally, no difference in glucose homeostasis and insulin secretion were observed, suggesting that incretins are counteracting the mTORC2 deficiency. Mechanistically, glucagon-like peptide-1 (GLP-1), but not gastric inhibitory polypeptide (GIP), rescued insulin secretion in vivo and in vitro by improving actin polymerization in βRicKO islets. In conclusion, mTORC2 regulates glucose-stimulated insulin secretion by promoting actin filament remodeling.NEW & NOTEWORTHY The current studies uncover a novel mechanism linking mTORC2 signaling to glucose-stimulated insulin secretion by modulation of the actin filaments. This work also underscores the important role of GLP-1 in rescuing defects in insulin secretion by modulating actin polymerization and suggests that this effect is independent of mTORC2 signaling.
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Affiliation(s)
- Manuel Blandino-Rosano
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Joshua O Scheys
- Medical School, Division of Metabolism, Endocrinology, and Diabetes and Brehm Center for Diabetes Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Joao Pedro Werneck-de-Castro
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Ruy A Louzada
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Joana Almaça
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
| | - Gil Leibowitz
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | | | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
- Miami VA Healthcare System, Miami, Florida
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5
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Israeli T, Riahi Y, Garzon P, Louzada RA, Werneck-de-Castro JP, Blandino-Rosano M, Yeroslaviz-Stolper R, Kadosh L, Tornovsky-Babeay S, Hacker G, Israeli N, Agmon O, Tirosh B, Cerasi E, Bernal-Mizrachi E, Leibowitz G. Nutrient Sensor mTORC1 Regulates Insulin Secretion by Modulating β-Cell Autophagy. Diabetes 2022; 71:453-469. [PMID: 34862201 PMCID: PMC8893949 DOI: 10.2337/db21-0281] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 11/30/2021] [Indexed: 01/23/2023]
Abstract
The dynamic regulation of autophagy in β-cells by cycles of fasting-feeding and its effects on insulin secretion are unknown. In β-cells, mechanistic target of rapamycin complex 1 (mTORC1) is inhibited while fasting and is rapidly stimulated during refeeding by a single amino acid, leucine, and glucose. Stimulation of mTORC1 by nutrients inhibited the autophagy initiator ULK1 and the transcription factor TFEB, thereby preventing autophagy when β-cells were continuously exposed to nutrients. Inhibition of mTORC1 by Raptor knockout mimicked the effects of fasting and stimulated autophagy while inhibiting insulin secretion, whereas moderate inhibition of autophagy under these conditions rescued insulin secretion. These results show that mTORC1 regulates insulin secretion through modulation of autophagy under different nutritional situations. In the fasting state, autophagy is regulated in an mTORC1-dependent manner, and its stimulation is required to keep insulin levels low, thereby preventing hypoglycemia. Reciprocally, stimulation of mTORC1 by elevated leucine and glucose, which is common in obesity, may promote hyperinsulinemia by inhibiting autophagy.
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Affiliation(s)
- Tal Israeli
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Yael Riahi
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Perla Garzon
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ruy Andrade Louzada
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Joao Pedro Werneck-de-Castro
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Manuel Blandino-Rosano
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Roni Yeroslaviz-Stolper
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Liat Kadosh
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Sharona Tornovsky-Babeay
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Gilad Hacker
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Nitzan Israeli
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Orly Agmon
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Boaz Tirosh
- Stress Signaling Laboratory, School of Pharmacy, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Erol Cerasi
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Gil Leibowitz
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
- Corresponding author: Gil Leibowitz,
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6
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Bozadjieva Kramer N, Lubaczeuski C, Blandino-Rosano M, Barker G, Gittes GK, Caicedo A, Bernal-Mizrachi E. Glucagon Resistance and Decreased Susceptibility to Diabetes in a Model of Chronic Hyperglucagonemia. Diabetes 2021; 70:477-491. [PMID: 33239450 PMCID: PMC7881862 DOI: 10.2337/db20-0440] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 11/18/2020] [Indexed: 02/07/2023]
Abstract
Elevation of glucagon levels and increase in α-cell mass are associated with states of hyperglycemia in diabetes. Our previous studies have highlighted the role of nutrient signaling via mTOR complex 1 (mTORC1) regulation that controls glucagon secretion and α-cell mass. In the current studies we investigated the effects of activation of nutrient signaling by conditional deletion of the mTORC1 inhibitor, TSC2, in α-cells (αTSC2KO). We showed that activation of mTORC1 signaling is sufficient to induce chronic hyperglucagonemia as a result of α-cell proliferation, cell size, and mass expansion. Hyperglucagonemia in αTSC2KO was associated with an increase in glucagon content and enhanced glucagon secretion. This model allowed us to identify the effects of chronic hyperglucagonemia on glucose homeostasis by inducing insulin secretion and resistance to glucagon in the liver. Liver glucagon resistance in αTSC2KO mice was characterized by reduced expression of the glucagon receptor (GCGR), PEPCK, and genes involved in amino acid metabolism and urea production. Glucagon resistance in αTSC2KO mice was associated with improved glucose levels in streptozotocin-induced β-cell destruction and high-fat diet-induced glucose intolerance. These studies demonstrate that chronic hyperglucagonemia can improve glucose homeostasis by inducing glucagon resistance in the liver.
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Affiliation(s)
- Nadejda Bozadjieva Kramer
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI
- Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
| | - Camila Lubaczeuski
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Manuel Blandino-Rosano
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Grant Barker
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - George K Gittes
- UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburg, PA
| | - Alejandro Caicedo
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Miller School of Medicine, University of Miami, Miami, FL
- Veterans Affairs Medical Center, Miami, FL
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7
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Werneck-de-Castro JP, Blandino-Rosano M, Hilfiker-Kleiner D, Bernal-Mizrachi E. Glucose stimulates microRNA-199 expression in murine pancreatic β-cells. J Biol Chem 2020; 295:1261-1270. [PMID: 31882540 PMCID: PMC6996880 DOI: 10.1074/jbc.ra119.010356] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/12/2019] [Indexed: 12/15/2022] Open
Abstract
MicroRNA 199 (miR-199) negatively impacts pancreatic β-cell function and its expression is highly increased in islets from diabetic mice as well as in plasma of diabetic patients. Here we investigated how miR-199 expression is regulated in β-cells by assessing expression of miR-199 precursors (primiR-199a1, primiR-199a2, and primiR-199b) and mature miR-199 (miR-199-3p and miR-199-5p) and promoter transcriptional activity assays in mouse islets and mouse insulinoma cells (MIN6) under different stimuli. We found that mouse islets equally express miR-199-3p and miR-199-5p. However, the primiRNA expression levels differed; although primiR-199a1 expression was about 30% greater than that of primiR-199a2, primiR-199b is barely detected in islets. We observed a 2-fold increase in primiR-199a1 and primiR-199a2 mRNA levels in mouse islets cultured in 10 mm glucose compared with 5.5 mm glucose. Similar responses to glucose were observed in MIN6 cells. Exposure to 30 mm KCl to induce membrane depolarization and calcium influx increased expression of primiR-199a2 but not of primiR-199a1 in MIN6 cells, indicating that calcium influx was involved. Transcriptional activity studies in MIN6 cells also revealed that primiR-199a2 promoter activity was enhanced by glucose and reduced by 2-deoxy-D-glucose-induced starvation. KCl and the potassium channel blocker tolbutamide also stimulated primiR-199a2 promoter activity. Calcium channel blockade by nifedipine reduced primiR-199a2 promoter activity in MIN6 cells, and diazoxide-mediated calcium influx inhibition blunted glucose up-regulation of miR-199-3p in islets. In conclusion, we uncover that glucose acutely up-regulates miR-199 family expression in β-cells. Glucose metabolism and calcium influx are involved in primiR-199a2 expression but not primiR-199a1 expression.
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Affiliation(s)
- Joao Pedro Werneck-de-Castro
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami, Miller School of Medicine, Miami, Florida 33136,Miami Veterans Affairs Health Care System, Miami, Florida 33136
| | - Manuel Blandino-Rosano
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami, Miller School of Medicine, Miami, Florida 33136
| | | | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami, Miller School of Medicine, Miami, Florida 33136 .,Miami Veterans Affairs Health Care System, Miami, Florida 33136
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8
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Werneck-de-Castro JP, Blandino-Rosano M, Hilfiker-Kleiner D, Bernal-Mizrachi E. Glucose stimulates microRNA-199 expression in murine pancreatic β-cells. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49884-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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9
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Prada-Oliveira JA, Camacho-Ramirez A, Salas-Alvarez J, Campos-Martinez FJ, Lechuga-Sancho AM, Almorza-Gomar D, Blandino-Rosano M, Perez-Arana GM. GLP-1 mediated improvement of the glucose tolerance in the T2DM GK rat model after massive jejunal resection. Ann Anat 2019; 223:1-7. [DOI: 10.1016/j.aanat.2019.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 01/04/2019] [Accepted: 01/23/2019] [Indexed: 12/25/2022]
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10
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Berman DM, Ruiz P, Blandino-Rosano M, Bernal-Mizrachi E, Kenyon NS. Steroid-Free Immune Suppression Impairs Glycemic Control in a Healthy Cynomolgus Monkey. Cell Transplant 2019; 28:262-268. [PMID: 30675800 PMCID: PMC6425109 DOI: 10.1177/0963689718823505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The need for chronic immune suppression (IS) is one of the hurdles precluding widespread use of islet cell transplantation to restore glycemic control in patients with type 1 diabetes. We report the case of a healthy nonhuman primate (NHP) treated on and off for over 2.5 years with steroid-free IS, consisting of daclizumab induction and maintenance therapy with rapamycin and low dose tacrolimus. Treatment for 1 year resulted in a striking destabilization of glycemic control, with concomitant decreases in fasting c-peptide and insulin levels. Although these changes gradually reversed during a wash out period of 7 months, retreatment with the same therapy led to accelerated deterioration in glycemic control. Intravenous glucose tolerance and percentage of glycosylated hemoglobin testing further supported a dramatic effect on metabolic control. IS also led to decreases in weight during treatment. Histological evaluation of the pancreas revealed islet hyperplasia, with varying sizes and endocrine cell ratios that differed from normal islet composition, and parenchymal infiltration with adipose tissue. These deleterious effects of IS on glucose control and endocrine components in the native pancreas of a healthy NHP suggest that IS agents commonly utilized for islet transplantation may contribute to failure in islet allograft function in long-term transplant patients.
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Affiliation(s)
- Dora M Berman
- 1 Diabetes Research Institute, Miller School of Medicine, University of Miami, FL, USA.,2 Department of Surgery, Miller School of Medicine, University of Miami, FL, USA
| | - Phillip Ruiz
- 3 Department of Pathology and Microbiology, Miller School of Medicine, University of Miami, FL, USA
| | - Manuel Blandino-Rosano
- 4 Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, FL, USA
| | - Ernesto Bernal-Mizrachi
- 4 Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, FL, USA
| | - Norma S Kenyon
- 1 Diabetes Research Institute, Miller School of Medicine, University of Miami, FL, USA.,2 Department of Surgery, Miller School of Medicine, University of Miami, FL, USA.,5 Department of Immunology, Miller School of Medicine, University of Miami, FL, USA
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11
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Navarro G, Allard C, Morford JJ, Xu W, Liu S, Molinas AJ, Butcher SM, Fine NH, Blandino-Rosano M, Sure VN, Yu S, Zhang R, Münzberg H, Jacobson DA, Katakam PV, Hodson DJ, Bernal-Mizrachi E, Zsombok A, Mauvais-Jarvis F. Androgen excess in pancreatic β cells and neurons predisposes female mice to type 2 diabetes. JCI Insight 2018; 3:98607. [PMID: 29925687 PMCID: PMC6124401 DOI: 10.1172/jci.insight.98607] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 05/10/2018] [Indexed: 11/17/2022] Open
Abstract
Androgen excess predisposes women to type 2 diabetes (T2D), but the mechanism of this is poorly understood. We report that female mice fed a Western diet and exposed to chronic androgen excess using dihydrotestosterone (DHT) exhibit hyperinsulinemia and insulin resistance associated with secondary pancreatic β cell failure, leading to hyperglycemia. These abnormalities are not observed in mice lacking the androgen receptor (AR) in β cells and partially in neurons of the mediobasal hypothalamus (MBH) as well as in mice lacking AR selectively in neurons. Accordingly, i.c.v. infusion of DHT produces hyperinsulinemia and insulin resistance in female WT mice. We observe that acute DHT produces insulin hypersecretion in response to glucose in cultured female mouse and human pancreatic islets in an AR-dependent manner via a cAMP- and mTOR-dependent pathway. Acute DHT exposure increases mitochondrial respiration and oxygen consumption in female cultured islets. As a result, chronic DHT exposure in vivo promotes islet oxidative damage and susceptibility to additional stress induced by streptozotocin via AR in β cells. This study suggests that excess androgen predisposes female mice to T2D following AR activation in neurons, producing peripheral insulin resistance, and in pancreatic β cells, promoting insulin hypersecretion, oxidative injury, and secondary β cell failure.
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Affiliation(s)
- Guadalupe Navarro
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Camille Allard
- Department of Medicine, Section of Endocrinology and Metabolism, and
| | - Jamie J. Morford
- Department of Medicine, Section of Endocrinology and Metabolism, and
| | - Weiwei Xu
- Department of Medicine, Section of Endocrinology and Metabolism, and
| | - Suhuan Liu
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Adrien J.R. Molinas
- Department of Physiology, Tulane University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA
| | - Sierra M. Butcher
- Department of Physiology, Tulane University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA
| | - Nicholas H.F. Fine
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, United Kingdom
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Venkata N. Sure
- Department of Pharmacology, Tulane University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA
| | - Sangho Yu
- Department of Neurobiology of Nutrition and Metabolism, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Rui Zhang
- Department of Neurobiology of Nutrition and Metabolism, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Heike Münzberg
- Department of Neurobiology of Nutrition and Metabolism, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Prasad V. Katakam
- Department of Pharmacology, Tulane University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA
| | - David J. Hodson
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, United Kingdom
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Andrea Zsombok
- Department of Physiology, Tulane University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA
| | - Franck Mauvais-Jarvis
- Department of Medicine, Section of Endocrinology and Metabolism, and
- Department of Physiology, Tulane University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA
- Tulane Brain Institute and
- Southeast Louisiana Veterans Healthcare System, New Orleans, Louisiana, USA
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12
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Bozadjieva N, Blandino-Rosano M, Chase J, Dai XQ, Cummings K, Gimeno J, Dean D, Powers AC, Gittes GK, Rüegg MA, Hall MN, MacDonald PE, Bernal-Mizrachi E. Loss of mTORC1 signaling alters pancreatic α cell mass and impairs glucagon secretion. J Clin Invest 2017; 127:4379-4393. [PMID: 29106387 DOI: 10.1172/jci90004] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 09/26/2017] [Indexed: 01/19/2023] Open
Abstract
Glucagon plays a major role in the regulation of glucose homeostasis during fed and fasting states. However, the mechanisms responsible for the regulation of pancreatic α cell mass and function are not completely understood. In the current study, we identified mTOR complex 1 (mTORC1) as a major regulator of α cell mass and glucagon secretion. Using mice with tissue-specific deletion of the mTORC1 regulator Raptor in α cells (αRaptorKO), we showed that mTORC1 signaling is dispensable for α cell development, but essential for α cell maturation during the transition from a milk-based diet to a chow-based diet after weaning. Moreover, inhibition of mTORC1 signaling in αRaptorKO mice and in WT animals exposed to chronic rapamycin administration decreased glucagon content and glucagon secretion. In αRaptorKO mice, impaired glucagon secretion occurred in response to different secretagogues and was mediated by alterations in KATP channel subunit expression and activity. Additionally, our data identify the mTORC1/FoxA2 axis as a link between mTORC1 and transcriptional regulation of key genes responsible for α cell function. Thus, our results reveal a potential function of mTORC1 in nutrient-dependent regulation of glucagon secretion and identify a role for mTORC1 in controlling α cell-mass maintenance.
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Affiliation(s)
- Nadejda Bozadjieva
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Jennifer Chase
- Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Xiao-Qing Dai
- Alberta Diabetes Institute and Department of Pharmacology, Edmonton, Alberta, Canada
| | - Kelsey Cummings
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and
| | - Jennifer Gimeno
- Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Danielle Dean
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, and
| | - Alvin C Powers
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, and.,Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee, USA.,VA Tennessee Valley Healthcare, Nashville, Tennessee, USA
| | - George K Gittes
- Children's Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | | | | | - Patrick E MacDonald
- Alberta Diabetes Institute and Department of Pharmacology, Edmonton, Alberta, Canada
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Graduate Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA.,Department of Internal Medicine, Division Endocrinology, Metabolism and Diabetes, Miller School of Medicine, University of Miami, Miami, Florida, USA.,Veterans Affairs Medical Center, Miami, Florida, USA
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13
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Alejandro EU, Bozadjieva N, Blandino-Rosano M, Wasan MA, Elghazi L, Vadrevu S, Satin L, Bernal-Mizrachi E. Overexpression of Kinase-Dead mTOR Impairs Glucose Homeostasis by Regulating Insulin Secretion and Not β-Cell Mass. Diabetes 2017; 66:2150-2162. [PMID: 28546423 PMCID: PMC5521866 DOI: 10.2337/db16-1349] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 05/01/2017] [Indexed: 12/20/2022]
Abstract
Regulation of glucose homeostasis by insulin depends on β-cell growth and function. Nutrients and growth factor stimuli converge on the conserved protein kinase mechanistic target of rapamycin (mTOR), existing in two complexes, mTORC1 and mTORC2. To understand the functional relevance of mTOR enzymatic activity in β-cell development and glucose homeostasis, we generated mice overexpressing either one or two copies of a kinase-dead mTOR mutant (KD-mTOR) transgene exclusively in β-cells. We examined glucose homeostasis and β-cell function of these mice fed a control chow or high-fat diet. Mice with two copies of the transgene [RIPCre;KD-mTOR (Homozygous)] develop glucose intolerance due to a defect in β-cell function without alterations in β-cell mass with control chow. Islets from RIPCre;KD-mTOR (Homozygous) mice showed reduced mTORC1 and mTORC2 signaling along with transcripts and protein levels of Pdx-1. Islets with reduced mTORC2 signaling in their β-cells (RIPCre;Rictorfl/fl) also showed reduced Pdx-1. When challenged with a high-fat diet, mice carrying one copy of KD-mTOR mutant transgene developed glucose intolerance and β-cell insulin secretion defect but showed no changes in β-cell mass. These findings suggest that the mTOR-mediated signaling pathway is not essential to β-cell growth but is involved in regulating β-cell function in normal and diabetogenic conditions.
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Affiliation(s)
- Emilyn U Alejandro
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN
| | - Nadejda Bozadjieva
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Manuel Blandino-Rosano
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, University of Miami, Miami, FL
| | - Michelle Ann Wasan
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN
| | - Lynda Elghazi
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | | | - Leslie Satin
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
| | - Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, University of Miami, Miami, FL
- VA Ann Arbor Healthcare System, Ann Arbor, MI
- Miami VA Healthcare System, Miami, FL
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14
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Camacho-Ramírez A, Blandino-Rosano M, Segundo-Iglesias MC, Lechuga-Sancho AM, Aguilar-Diosdado M, Pérez-Arana GM, Prada-Oliveira JA. Bariatric surgery influences β-cell turnover in non obese rats. Histol Histopathol 2017; 32:1341-1350. [PMID: 28567716 DOI: 10.14670/hh-11-909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The aim of this study was to investigate the relation between the different bariatric surgeries and pancreatic β-cell turnover. MATERIAL AND METHODS We used healthy adult male Wistar rats to undergo the different techniques. Three surgical techniques were developed (malabsorptive, Sleeve gastrectomy and Roux-Y Gastric Bypass-), together with two control groups (Sham and fasting control). Pancreatic β-cell mass was measured, as well as apoptosis, proliferation and neogenesis related to cellular turnover. Otherwise, we measured the functional issues to elucidate the physiological role that these surgical techniques trigger in the carbohydrate metabolism (e.g. food intake, weight gain, intraperitoneal glucose tolerance test, and basal glycaemia). Results included the differences in phenotypes of the rat after the surgery. The rats did not show important differences in glycaemic parameters between the surgical groups. The β-cell mass presented modifications related with proliferation processes. A significant increase of β-cell mass in the malabsorptive technique was reported. On the other hand, the peripheral resistance to insulin tended to be reduced in rats which underwent malabsorptive and mixed techniques. CONCLUSION This work showed an increase in β-cell mass after the resection of an important portion of small bowel. The Roux-Y Gastric Bypass produced a non-significant increase in β-cell mass. We considered that these implications of surgery over the endocrine pancreas must be one of the mechanisms related to the improvement of type 2 Diabetes mellitus following bariatric surgery.
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Affiliation(s)
| | - Manuel Blandino-Rosano
- Department of Endocrinology, Diabetes and Metabolism Division, Miller School of Medicine, University of Miami, FL, USA
| | - M Carmen Segundo-Iglesias
- Endocrinology and Metabolism Clinical Unit, Puerta del Mar Universitary Hospital, University of Cádiz, Cádiz, Spain
| | - Alfonso M Lechuga-Sancho
- Department of Child and Mother Health and Radiology, Pediatric Endocrinology, Puerta del Mar University Hospital Universitary of Cádiz, Cádiz, Spain
| | - Manuel Aguilar-Diosdado
- Endocrinology and Metabolism Clinical Unit, Puerta del Mar Universitary Hospital, University of Cádiz, Cádiz, Spain
| | - Gonzalo M Pérez-Arana
- Endocrinology and Metabolism Clinical Unit, Puerta del Mar Universitary Hospital, University of Cádiz, Cádiz, Spain
| | - J Arturo Prada-Oliveira
- Department of Human Anatomy and Embryology, Faculty of Medicine, University of Cádiz, Cádiz, Spain.
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15
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Elghazi L, Blandino-Rosano M, Alejandro E, Cras-Méneur C, Bernal-Mizrachi E. Role of nutrients and mTOR signaling in the regulation of pancreatic progenitors development. Mol Metab 2017; 6:560-573. [PMID: 28580286 PMCID: PMC5444096 DOI: 10.1016/j.molmet.2017.03.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/14/2017] [Accepted: 03/22/2017] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE Poor fetal nutrition increases the risk of type 2 diabetes in the offspring at least in part by reduced embryonic β-cell growth and impaired function. However, it is not entirely clear how fetal nutrients and growth factors impact β-cells during development to alter glucose homeostasis and metabolism later in life. The current experiments aimed to test the impact of fetal nutrients and growth factors on endocrine development and how these signals acting on mTOR signaling regulate β-cell mass and glucose homeostasis. METHOD Pancreatic rudiments in culture were used to study the role of glucose, growth factors, and amino acids on β-cell development. The number and proliferation of pancreatic and endocrine progenitor were assessed in the presence or absence of rapamycin. The impact of mTOR signaling in vivo on pancreas development and glucose homeostasis was assessed in models deficient for mTOR or Raptor in Pdx1 expressing pancreatic progenitors. RESULTS We found that amino acid concentrations, and leucine in particular, enhance the number of pancreatic and endocrine progenitors and are essential for growth factor induced proliferation. Rapamycin, an mTORC1 complex inhibitor, reduced the number and proliferation of pancreatic and endocrine progenitors. Mice lacking mTOR in pancreatic progenitors exhibited hyperglycemia in neonates, hypoinsulinemia and pancreatic agenesis/hypoplasia with pancreas rudiments containing ductal structures lacking differentiated acinar and endocrine cells. In addition, loss of mTORC1 by deletion of raptor in pancreatic progenitors reduced pancreas size with reduced number of β-cells. CONCLUSION Together, these results suggest that amino acids concentrations and in particular leucine modulates growth responses of pancreatic and endocrine progenitors and that mTOR signaling is critical for these responses. Inactivation of mTOR and raptor in pancreatic progenitors suggested that alterations in some of the components of this pathway during development could be a cause of pancreatic agenesis/hypoplasia and hyperglycemia.
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Affiliation(s)
- Lynda Elghazi
- University of Michigan in Ann Arbor, Internal Medicine Department, MEND Division, Ann Arbor, MI, USA
| | - Manuel Blandino-Rosano
- University of Miami Miller School of Medicine and Miami VA Health Care System, Division of Endocrinology, Diabetes and Metabolism, Miami, FL, USA
| | - Emilyn Alejandro
- University of Michigan in Ann Arbor, Internal Medicine Department, MEND Division, Ann Arbor, MI, USA
- University of Minnesota, Department of Integrative Biology & Physiology, Minneapolis, MN, USA
| | - Corentin Cras-Méneur
- University of Michigan in Ann Arbor, Internal Medicine Department, MEND Division, Ann Arbor, MI, USA
| | - Ernesto Bernal-Mizrachi
- University of Miami Miller School of Medicine and Miami VA Health Care System, Division of Endocrinology, Diabetes and Metabolism, Miami, FL, USA
- Corresponding author. Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine and Miami VA Health Care System, USA. Fax: +1 (305) 243 4039.Department of Internal MedicineDivision of Endocrinology, Diabetes and MetabolismUniversity of Miami Miller School of Medicine and Miami VA Health Care SystemUSA
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16
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Blandino-Rosano M, Scheys JO, Jimenez-Palomares M, Barbaresso R, Bender AS, Yanagiya A, Liu M, Rui L, Sonenberg N, Bernal-Mizrachi E. 4E-BP2/SH2B1/IRS2 Are Part of a Novel Feedback Loop That Controls β-Cell Mass. Diabetes 2016; 65:2235-48. [PMID: 27217487 PMCID: PMC4955981 DOI: 10.2337/db15-1443] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 05/09/2016] [Indexed: 01/08/2023]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) regulates several biological processes, although the key downstream mechanisms responsible for these effects are poorly defined. Using mice with deletion of eukaryotic translation initiation factor 4E-binding protein 2 (4E-BP2), we determine that this downstream target is a major regulator of glucose homeostasis and β-cell mass, proliferation, and survival by increasing insulin receptor substrate 2 (IRS2) levels and identify a novel feedback mechanism by which mTORC1 signaling increases IRS2 levels. In this feedback loop, we show that 4E-BP2 deletion induces translation of the adaptor protein SH2B1 and promotes the formation of a complex with IRS2 and Janus kinase 2, preventing IRS2 ubiquitination. The changes in IRS2 levels result in increases in cell cycle progression, cell survival, and β-cell mass by increasing Akt signaling and reducing p27 levels. Importantly, 4E-BP2 deletion confers resistance to cytokine treatment in vitro. Our data identify SH2B1 as a major regulator of IRS2 stability, demonstrate a novel feedback mechanism linking mTORC1 signaling with IRS2, and identify 4E-BP2 as a major regulator of proliferation and survival of β-cells.
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Affiliation(s)
- Manuel Blandino-Rosano
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI
| | - Joshua O Scheys
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI
| | - Margarita Jimenez-Palomares
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI
| | - Rebecca Barbaresso
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI
| | - Aaron S Bender
- Diabetes, Obesity and Metabolism Institute, The Icahn School of Medicine at Mount Sinai, New York, NY
| | - Akiko Yanagiya
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Ming Liu
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI
| | - Liangyou Rui
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI VA Ann Arbor Healthcare System, Ann Arbor, MI
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17
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Alejandro EU, Gregg B, Blandino-Rosano M, Cras-Méneur C, Bernal-Mizrachi E. Natural history of β-cell adaptation and failure in type 2 diabetes. Mol Aspects Med 2014; 42:19-41. [PMID: 25542976 DOI: 10.1016/j.mam.2014.12.002] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 11/04/2014] [Accepted: 12/05/2014] [Indexed: 02/07/2023]
Abstract
Type 2 diabetes mellitus (T2D) is a complex disease characterized by β-cell failure in the setting of insulin resistance. The current evidence suggests that genetic predisposition, and environmental factors can impair the capacity of the β-cells to respond to insulin resistance and ultimately lead to their failure. However, genetic studies have demonstrated that known variants account for less than 10% of the overall estimated T2D risk, suggesting that additional unidentified factors contribute to susceptibility of this disease. In this review, we will discuss the different stages that contribute to the development of β-cell failure in T2D. We divide the natural history of this process in three major stages: susceptibility, β-cell adaptation and β-cell failure, and provide an overview of the molecular mechanisms involved. Further research into mechanisms will reveal key modulators of β-cell failure and thus identify possible novel therapeutic targets and potential interventions to protect against β-cell failure.
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Affiliation(s)
- Emilyn U Alejandro
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA
| | - Brigid Gregg
- Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA
| | - Corentin Cras-Méneur
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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Gregg B, Elghazi L, Alejandro EU, Smith MR, Blandino-Rosano M, El-Gabri D, Cras-Méneur C, Bernal-Mizrachi E. Exposure of mouse embryonic pancreas to metformin enhances the number of pancreatic progenitors. Diabetologia 2014; 57:2566-75. [PMID: 25249235 PMCID: PMC4417192 DOI: 10.1007/s00125-014-3379-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 08/28/2014] [Indexed: 01/23/2023]
Abstract
AIMS/HYPOTHESIS Developing beta cells are vulnerable to nutrient environmental signals. Early developmental processes that alter the number of pancreatic progenitors can determine the number of beta cells present at birth. Metformin, the most widely used oral agent for treating diabetes, alters intracellular energy status in part by increasing AMP-activated protein kinase (AMPK) signalling. This study examined the effect of metformin on developing pancreas and beta cells. METHODS Pancreatic rudiments from CD-1 mice at embryonic day 13.0 (E13.0) were cultured with metformin, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR, an AMPK activator) or vehicle control in vitro. In another set of studies, pregnant C57BL/6 mice were treated with metformin throughout gestation. Embryonic (E14.0) and neonatal pancreases were then analysed for their morphometry. RESULTS In vitro metformin treatment led to an increase in the proliferation and number of pancreatic duodenal homeobox 1-positive (PDX1(+)) progenitors. These results were reproduced by in vitro culture of embryonic pancreas rudiments with AICAR, suggesting that AMPK activation was involved. Similarly, metformin administration to pregnant dams induced an increase in both PDX1(+) and neurogenin 3-positive progenitors in the embryonic pancreas at E14.0 and these changes resulted in an increased beta cell fraction in neonates. CONCLUSIONS/INTERPRETATION These results indicate that exposure to metformin during gestation modulates the early steps of beta cell development (prior to E14.0) towards an increase in the number of pancreatic and endocrine progenitors. These changes ultimately result in a higher beta cell fraction at birth. These findings are of clinical importance given that metformin is currently used for the treatment of gestational diabetes.
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Affiliation(s)
- Brigid Gregg
- Department of Pediatrics, Division of Endocrinology, Diabetes and Metabolism, University of Michigan, Ann Arbor, Michigan, USA
| | - Lynda Elghazi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Emilyn U. Alejandro
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Michelle R. Smith
- Department of Pediatrics, Division of Endocrinology, Diabetes and Metabolism, University of Michigan, Ann Arbor, Michigan, USA
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Deena El-Gabri
- Department of Pediatrics, Division of Endocrinology, Diabetes and Metabolism, University of Michigan, Ann Arbor, Michigan, USA
| | - Corentin Cras-Méneur
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan, USA
- VA Ann Arbor Healthcare System, Ann Arbor, Michigan
- Corresponding author: Dr. Ernesto Bernal-Mizrachi VA Ann Arbor Healthcare System, Ann Arbor, Michigan., Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan 48109-0678, USA., Phone: +1 (734) 615-0262, Fax: +1 (734) 936-6684,
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Sadagurski M, Landeryou T, Blandino-Rosano M, Cady G, Elghazi L, Meister D, See L, Bartke A, Bernal-Mizrachi E, Miller RA. Long-lived crowded-litter mice exhibit lasting effects on insulin sensitivity and energy homeostasis. Am J Physiol Endocrinol Metab 2014; 306:E1305-14. [PMID: 24735888 PMCID: PMC4042097 DOI: 10.1152/ajpendo.00031.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The action of nutrients on early postnatal growth can influence mammalian aging and longevity. Recent work has demonstrated that limiting nutrient availability in the first 3 wk of life [by increasing the number of pups in the crowded-litter (CL) model] leads to extension of mean and maximal lifespan in genetically normal mice. In this study, we aimed to characterize the impact of early-life nutrient intervention on glucose metabolism and energy homeostasis in CL mice. In our study, we used mice from litters supplemented to 12 or 15 pups and compared those to control litters limited to eight pups. At weaning and then throughout adult life, CL mice are significantly leaner and consume more oxygen relative to control mice. At 6 mo of age, CL mice had low fasting leptin concentrations, and low-dose leptin injections reduced body weight and food intake more in CL female mice than in controls. At 22 mo, CL female mice also have smaller adipocytes compared with controls. Glucose and insulin tolerance tests show an increase in insulin sensitivity in 6 mo old CL male mice, and females become more insulin sensitive later in life. Furthermore, β-cell mass was significantly reduced in the CL male mice and was associated with reduction in β-cell proliferation rate in these mice. Together, these data show that early-life nutrient intervention has a significant lifelong effect on metabolic characteristics that may contribute to the increased lifespan of CL mice.
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Affiliation(s)
- Marianna Sadagurski
- Department of Internal Medicine, Division of Geriatric and Palliative Medicine, University of Michigan, Ann Arbor, Michigan;
| | - Taylor Landeryou
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan
| | - Gillian Cady
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan
| | - Lynda Elghazi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan
| | - Daniel Meister
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan
| | - Lauren See
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan
| | - Andrzej Bartke
- Department of Internal Medicine-Geriatrics Research, Southern Illinois University School of Medicine, Springfield, Illinois; and
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan; Endocrinology Section, Medical Service, Veterans Affairs Medical Center, Ann Arbor, Michigan
| | - Richard A Miller
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, Michigan
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Blandino-Rosano M, Chen AY, Scheys JO, Alejandro EU, Gould AP, Taranukha T, Elghazi L, Cras-Méneur C, Bernal-Mizrachi E. mTORC1 signaling and regulation of pancreatic β-cell mass. Cell Cycle 2012; 11:1892-902. [PMID: 22544327 DOI: 10.4161/cc.20036] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The capacity of β cells to expand in response to insulin resistance is a critical factor in the development of type 2 diabetes. Proliferation of β cells is a major component for these adaptive responses in animal models. The extracellular signals responsible for β-cell expansion include growth factors, such as insulin, and nutrients, such as glucose and amino acids. AKT activation is one of the important components linking growth signals to the regulation of β-cell expansion. Downstream of AKT, tuberous sclerosis complex 1 and 2 (TSC1/2) and mechanistic target of rapamycin complex 1 (mTORC1) signaling have emerged as prime candidates in this process, because they integrate signals from growth factors and nutrients. Recent studies demonstrate the importance of mTORC1 signaling in β cells. This review will discuss recent advances in the understanding of how this pathway regulates β-cell mass and present data on the role of TSC1 in modulation of β-cell mass. Herein, we also demonstrate that deletion of Tsc1 in pancreatic β cells results in improved glucose tolerance, hyperinsulinemia and expansion of β-cell mass that persists with aging.
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Affiliation(s)
- Manuel Blandino-Rosano
- Department of Internal Medicine; Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center; Ann Arbor, MI, USA
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Blandino-Rosano M, Alejandro EU, Sathyamurthy A, Scheys JO, Gregg B, Chen AY, Rachdi L, Weiss A, Barker DJ, Gould AP, Elghazi L, Bernal-Mizrachi E. Enhanced beta cell proliferation in mice overexpressing a constitutively active form of Akt and one allele of p21Cip. Diabetologia 2012; 55:1380-9. [PMID: 22327314 PMCID: PMC3646796 DOI: 10.1007/s00125-012-2465-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/19/2011] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS The ability of pancreatic beta cells to proliferate is critical both for normal tissue maintenance and in conditions where there is an increased demand for insulin. Protein kinase B(Akt) plays a major role in promoting proliferation in many cell types, including the insulin-producing beta cells. We have previously reported that mice overexpressing a constitutively active form of Akt(caAkt (Tg)) show enhanced beta cell proliferation that is associated with increased protein levels of cyclin D1, cyclin D2 and cyclin-dependent kinase inhibitor 1A (p21(Cip)). In the present study, we sought to assess the mechanisms responsible for augmented p21(Cip) levels in caAkt(Tg) mice and test the role of p21(Cip) in the proliferative responses induced by activation of Akt signalling. METHODS To gain a greater understanding of the relationship between Akt and p21(Cip), we evaluated the mechanisms involved in the modulation of p2(Cip) by Akt and the in vivo role of reduced p21(Cip) in proliferative responses induced by Akt. RESULTS Our experiments showed that Akt signalling regulates p21(Cip) transcription and protein stability. caAkt(Tg) /p21(Cip+/-) mice exhibited fasting and fed hypoglycaemia as well as hyperinsulinaemia when compared with caAkt(Tg) mice. Glucose tolerance tests revealed improved glucose tolerance in caAkt(Tg)/p21(Cip+/-) mice compared with caAkt (Tg). These changes resulted from increased proliferation, survival and beta cell mass in caAkt(Tg)/p21(Cip+/-) compared with caAkt(Tg) mice. CONCLUSIONS/INTERPRETATION Our data indicate that increased p21(Cip) levels in caAkt(Tg) mice act as a compensatory brake, protecting beta cells from unrestrained proliferation. These studies imply that p21(Cip) could play important roles in the adaptive responses of beta cells to proliferate in conditions such as in insulin resistance.
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Affiliation(s)
- M. Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - E. U. Alejandro
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. Sathyamurthy
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - J. O. Scheys
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - B. Gregg
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. Y. Chen
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - L. Rachdi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. Weiss
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - D. J. Barker
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. P. Gould
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - L. Elghazi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - E. Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
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Elghazi L, Balcazar N, Blandino-Rosano M, Cras-Méneur C, Fatrai S, Gould AP, Chi MM, Moley KH, Bernal-Mizrachi E. Decreased IRS signaling impairs beta-cell cycle progression and survival in transgenic mice overexpressing S6K in beta-cells. Diabetes 2010; 59:2390-9. [PMID: 20622167 PMCID: PMC3279560 DOI: 10.2337/db09-0851] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The purpose of this study was to evaluate the role of the S6K arm of mammalian target of rapamycin complex 1 (mTORC1) signaling in regulation of β-cell mass and function. Additionally, we aimed to delineate the importance of in vivo S6K activation in the regulation of insulin signaling and the extent to which alteration of insulin receptor substrate (IRS) signaling modulates β-cell mass and function. RESEARCH DESIGN AND METHODS The current experiments describe the phenotype of transgenic mice overexpressing a constitutively active form of S6K under the control of the rat insulin promoter. RESULTS Activation of S6K signaling in these mice improved insulin secretion in the absence of changes in β-cell mass. The lack of β-cell mass expansion resulted from decreased G(1)-S progression and increased apoptosis. This phenotype was associated with increased p16 and p27 and decreased Cdk2 levels. The changes in cell cycle were accompanied by diminished survival signals because of impaired IRS/Akt signaling. CONCLUSIONS This work defines the importance of S6K in regulation of β-cell cycle, cell size, function, and survival. These experiments also demonstrate that in vivo downregulation of IRS signaling by TORC1/S6K induces β-cell insulin resistance, and that this mechanism could explain some of the abnormalities that ultimately result in β-cell failure and diabetes in conditions of nutrient overload.
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Affiliation(s)
- Lynda Elghazi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
| | - Norman Balcazar
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
| | - Corentin Cras-Méneur
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
| | - Szabolcs Fatrai
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
| | - Aaron P. Gould
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
| | - Maggie M. Chi
- Department of Obstetrics/Gynecology, Washington University School of Medicine, St. Louis, Missouri
| | - Kelle H. Moley
- Department of Obstetrics/Gynecology, Washington University School of Medicine, St. Louis, Missouri
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, Michigan
- Corresponding author: Ernesto Bernal-Mizrachi,
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Pérez-Arana G, Blandino-Rosano M, Prada-Oliveira A, Aguilar-Diosdado M, Segundo C. Decrease in {beta}-cell proliferation precedes apoptosis during diabetes development in bio-breeding/worcester rat: beneficial role of Exendin-4. Endocrinology 2010; 151:2538-46. [PMID: 20410202 DOI: 10.1210/en.2009-1113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In autoimmune type 1 diabetes mellitus, proinflammatory cytokine-mediated apoptosis of beta-cells has been considered to be the first event directly responsible for beta-cell mass reduction. In the Bio-Breeding (BB) rat, an in vivo model used in the study of autoimmune diabetes, beta-cell apoptosis is observed from 9 wk of age and takes place after an insulitis period that begins at an earlier age. Previous studies by our group have shown an antiproliferative effect of proinflammatory cytokines on cultured beta-cells in Wistar rats, an effect that was partially reversed by Exendin-4, an analogue of glucagon-like peptide-1. In the current study, the changes in beta-cell apoptosis and proliferation during insulitis stage were also determined in pancreatic tissue sections in normal and thymectomized BB rats, as well as in Wistar rats of 5, 7, 9, and 11 wk of age. Although stable beta-cell proliferation in Wistar and thymectomized BB rats was observed along the course of the study, a decrease in beta-cell proliferation and beta-cell mass from the age of 5 wk, and prior to the commencement of apoptosis, was noted in BB rats. Exendin-4, in combination with anti-interferon-gamma antibody, induced a near-total recovery of beta-cell proliferation during the initial stages of insulitis. This highlights the importance of early intervention and, as well, the possibilities of new therapeutic approaches in preventing autoimmune diabetes by acting, initially, in the insulitis stage and, subsequently, on beta-cell regeneration and on beta-cell apoptosis.
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Affiliation(s)
- Gonzalo Pérez-Arana
- Investigation Unit and Endocrinology and Nutrition Service, Puerta del Mar Hospital, 11009 Cádiz, Spain
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Blandino-Rosano M, Perez-Arana G, Mellado-Gil JM, Segundo C, Aguilar-Diosdado M. Anti-proliferative effect of pro-inflammatory cytokines in cultured beta cells is associated with extracellular signal-regulated kinase 1/2 pathway inhibition: protective role of glucagon-like peptide -1. J Mol Endocrinol 2008; 41:35-44. [PMID: 18487229 DOI: 10.1677/jme-07-0154] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pancreatic beta-cell homeostasis is a balance between programmed cell death (apoptosis) and regeneration. Although autoimmune diabetes mellitus type 1 (DM1) is the most-studied cause of beta-cell mass loss by pro-inflammatory cytokine-induced apoptosis, influences of a pro-inflammatory environment on beta-cell regenerative response have been poorly studied. In this study, we assess the anti-proliferative effect of pro-inflammatory cytokines and glucose concentration on rat pancreatic beta cells and the potential protective role of glucagon-like peptide (GLP-1). Apoptotic and proliferating islet cells were stained using the DeadEnd Fluorimetric TUNEL System and 5-bromo-2'-deoxyuridine label respectively, in the presence-absence of varying concentrations of glucose, pro-inflammatory cytokines, and GLP-1. The potential signaling pathways involved were evaluated by western blot. Considerable anti-proliferative effects of pro-inflammatory cytokines interleukin (IL)-1beta, interferon (IFN)-gamma, and tumour necrosis factor-alpha (TNF-alpha) were observed. The effects were synergistic and independent of glucose concentration, and appeared to be mediated by the inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activation, the signaling pathway involved in beta-cell replication. GLP-1 completely reversed the cytokine-induced inhibition of ERK phosphorylation and increased beta-cell proliferation threefold in cytokine-treated cultures. While pro-inflammatory cytokines reduced islet cell ERK1/2 activation and beta-cell proliferation in pancreatic islet culture, GLP-1 was capable of reversing this effect. These data suggest a possible pharmacological application of GLP-1 in the treatment of early stage DM1, to prevent the loss of pancreatic beta cells as well as to delay the development of overt diabetes.
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Affiliation(s)
- M Blandino-Rosano
- Investigation Unit and Endocrinology and Nutrition Service, Puerta del Mar Hospital, Ana de Viya, 21, Cadiz 11009, Spain
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