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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: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [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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2
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Liu J, Fu H, Kang F, Ning G, Ni Q, Wang W, Wang Q. β-Cell glucokinase expression was increased in type 2 diabetes subjects with better glycemic control. J Diabetes 2023; 15:409-418. [PMID: 36942376 PMCID: PMC10172022 DOI: 10.1111/1753-0407.13380] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/22/2023] [Accepted: 02/26/2023] [Indexed: 03/23/2023] Open
Abstract
BACKGROUND Type 2 diabetes (T2D) is characterized by a progressive deterioration of β-cell function with a continuous decline in insulin secretion. Glucokinase (GCK) facilitates the rate-limiting step of glycolysis in pancreatic β-cells, to acquire the proper glucose-stimulated insulin secretion. Multiple glucokinase activators (GKAs) have been developed and clinically tested. However, the dynamic change of human pancreatic GCK expression during T2D progression has not been investigated. METHODS We evaluated GCK expression by measuring the average immunoreactivity of GCK in insulin+ or glucagon+ cells from pancreatic sections of 11 nondiabetic subjects (ND), 10 subjects with impaired fasting glucose (IFG), 9 with well-controlled T2D (wT2D), and 5 individuals with poorly controlled T2D (uT2D). We also assessed the relationship between GCK expression and adaptive unfolded protein response (UPR) in human diabetic β-cells. RESULTS We did not detect changes of GCK expression in IFG islets. However, we found β-cell GCK levels were significantly increased in T2D with adequate glucose control (wT2D) but not in T2D with poor glucose control (uT2D). Furthermore, there was a strong positive correlation between GCK expression and adaptive UPR (spliced X-box binding protein 1 [XBP1s] and activating transcription factor 4 [ATF4]), as well as functional maturity marker (urocortin-3 [UCN3]) in human diabetic β-cells. CONCLUSIONS Our study demonstrates that inductions of GCK enhanced adaptive UPR and UCN3 in human β-cells, which might be an adaptive mechanism during T2D progression. This finding provides a rationale for exploring novel molecules that activate β-cell GCK and thereby improve pharmacological treatment of T2D.
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Affiliation(s)
- Jingwen Liu
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hui Fu
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fuyun Kang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guang Ning
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Sino-French Research Center for Life Sciences and Genomics Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qicheng Ni
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weiqing Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qidi Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Sino-French Research Center for Life Sciences and Genomics Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Haythorne E, Lloyd M, Walsby-Tickle J, Tarasov AI, Sandbrink J, Portillo I, Exposito RT, Sachse G, Cyranka M, Rohm M, Rorsman P, McCullagh J, Ashcroft FM. Altered glycolysis triggers impaired mitochondrial metabolism and mTORC1 activation in diabetic β-cells. Nat Commun 2022; 13:6754. [PMID: 36376280 PMCID: PMC9663558 DOI: 10.1038/s41467-022-34095-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 10/13/2022] [Indexed: 11/16/2022] Open
Abstract
Chronic hyperglycaemia causes a dramatic decrease in mitochondrial metabolism and insulin content in pancreatic β-cells. This underlies the progressive decline in β-cell function in diabetes. However, the molecular mechanisms by which hyperglycaemia produces these effects remain unresolved. Using isolated islets and INS-1 cells, we show here that one or more glycolytic metabolites downstream of phosphofructokinase and upstream of GAPDH mediates the effects of chronic hyperglycemia. This metabolite stimulates marked upregulation of mTORC1 and concomitant downregulation of AMPK. Increased mTORC1 activity causes inhibition of pyruvate dehydrogenase which reduces pyruvate entry into the tricarboxylic acid cycle and partially accounts for the hyperglycaemia-induced reduction in oxidative phosphorylation and insulin secretion. In addition, hyperglycaemia (or diabetes) dramatically inhibits GAPDH activity, thereby impairing glucose metabolism. Our data also reveal that restricting glucose metabolism during hyperglycaemia prevents these changes and thus may be of therapeutic benefit. In summary, we have identified a pathway by which chronic hyperglycaemia reduces β-cell function.
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Affiliation(s)
- Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
| | - Matthew Lloyd
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - John Walsby-Tickle
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Jonas Sandbrink
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Idoia Portillo
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Raul Terron Exposito
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
- Institute for Diabetes and Cancer (IDC), Helmholtz Center, Munich, Neuherberg, 85764, Germany
| | - Gregor Sachse
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
- Brandenburg Medical School (Theodor Fontane), ZTM-BB, Brandenburg a. d. H, 14770, Germany
| | - Malgorzata Cyranka
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Maria Rohm
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
- Institute for Diabetes and Cancer (IDC), Helmholtz Center, Munich, Neuherberg, 85764, Germany
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - James McCullagh
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
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Ni Q, Sun J, Wang Y, Wang Y, Liu J, Ning G, Wang W, Wang Q. mTORC1 is required for epigenetic silencing during β-cell functional maturation. Mol Metab 2022; 64:101559. [PMID: 35940555 PMCID: PMC9418906 DOI: 10.1016/j.molmet.2022.101559] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 11/06/2022] Open
Abstract
Objective The mechanistic target of rapamycin complex 1 (mTORC1) is a key molecule that links nutrients, hormones, and growth factors to cell growth/function. Our previous studies have shown that mTORC1 is required for β-cell functional maturation and identity maintenance; however, the underlying mechanism is not fully understood. This work aimed to understand the underlying epigenetic mechanisms of mTORC1 in regulating β-cell functional maturation. Methods We performed Microarray, MeDIP-seq and ATAC-seq analysis to explore the abnormal epigenetic regulation in 8-week-old immature βRapKO islets. Moreover, DNMT3A was overexpressed in βRapKO islets by lentivirus, and the transcriptome changes and GSIS function were analyzed. Results We identified two major epigenetic silencing mechanisms, DNMT3A-dependent DNA methylation and PRC2-dependent H3K27me3 modification, which are responsible for functional immaturity of Raptor-deficient β-cell. Overexpression of DNMT3A partially reversed the immature transcriptome pattern and restored the impaired GSIS in Raptor-deficient β-cells. Moreover, we found that Raptor directly regulated PRC2/EED and H3K27me3 expression levels, as well as a group of immature genes marked with H3K27me3. Combined with ATAC-seq, MeDIP-seq and ChIP-seq, we identified β-cell immature genes with either DNA methylation and/or H3K27me3 modification. Conclusion The present study advances our understanding of the nutrient sensor mTORC1, by integrating environmental nutrient supply and epigenetic modification, i.e., DNMT3A-mediated DNA methylation and PRC2-mediated histone methylation in regulating β-cell identity and functional maturation, and therefore may impact the disease risk of type 2 diabetes. Rescued DNMT3A expression in Raptor-deficient islets partially reversed the abnormal induction of immature genes. EED/H3K27me3 were impaired in Raptor-ablated β-cell. DNA methylation and H3K27me3 are required for mTORC1-dependent epigenetic silencing of immature genes in β-cell.
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Bartolomé A, Pajvani UB. MTOR and Beta Cell Adaptation in T2D. J Clin Endocrinol Metab 2021; 106:e1466-e1467. [PMID: 33274365 PMCID: PMC7947821 DOI: 10.1210/clinem/dgaa906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Indexed: 11/26/2022]
Affiliation(s)
- Alberto Bartolomé
- Department of Medicine, Columbia University, New York, NY, USA
- Correspondence: Alberto Bartolomé, Columbia University Medical Center, Russ Berrie Science Pavilion, 1150 St. Nicholas Avenue, New York, NY 10032, USA. (); or Utpal B. Pajvani, Columbia University Medical Center, Russ Berrie Science Pavilion, 1150 St. Nicholas Avenue, New York, NY 10032, USA.
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, NY, USA
- Correspondence: Alberto Bartolomé, Columbia University Medical Center, Russ Berrie Science Pavilion, 1150 St. Nicholas Avenue, New York, NY 10032, USA. (); or Utpal B. Pajvani, Columbia University Medical Center, Russ Berrie Science Pavilion, 1150 St. Nicholas Avenue, New York, NY 10032, USA.
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Abstract
Cells metabolize nutrients for biosynthetic and bioenergetic needs to fuel growth and proliferation. The uptake of nutrients from the environment and their intracellular metabolism is a highly controlled process that involves cross talk between growth signaling and metabolic pathways. Despite constant fluctuations in nutrient availability and environmental signals, normal cells restore metabolic homeostasis to maintain cellular functions and prevent disease. A central signaling molecule that integrates growth with metabolism is the mechanistic target of rapamycin (mTOR). mTOR is a protein kinase that responds to levels of nutrients and growth signals. mTOR forms two protein complexes, mTORC1, which is sensitive to rapamycin, and mTORC2, which is not directly inhibited by this drug. Rapamycin has facilitated the discovery of the various functions of mTORC1 in metabolism. Genetic models that disrupt either mTORC1 or mTORC2 have expanded our knowledge of their cellular, tissue, as well as systemic functions in metabolism. Nevertheless, our knowledge of the regulation and functions of mTORC2, particularly in metabolism, has lagged behind. Since mTOR is an important target for cancer, aging, and other metabolism-related pathologies, understanding the distinct and overlapping regulation and functions of the two mTOR complexes is vital for the development of more effective therapeutic strategies. This review discusses the key discoveries and recent findings on the regulation and metabolic functions of the mTOR complexes. We highlight findings from cancer models but also discuss other examples of the mTOR-mediated metabolic reprogramming occurring in stem and immune cells, type 2 diabetes/obesity, neurodegenerative disorders, and aging.
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Affiliation(s)
- Angelia Szwed
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Eugene Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
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