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Yamagata K, Tsuyama T, Sato Y. Roles of β-Cell Hypoxia in the Progression of Type 2 Diabetes. Int J Mol Sci 2024; 25:4186. [PMID: 38673770 PMCID: PMC11050445 DOI: 10.3390/ijms25084186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Type 2 diabetes is a chronic disease marked by hyperglycemia; impaired insulin secretion by pancreatic β-cells is a hallmark of this disease. Recent studies have shown that hypoxia occurs in the β-cells of patients with type 2 diabetes and hypoxia, in turn, contributes to the insulin secretion defect and β-cell loss through various mechanisms, including the activation of hypoxia-inducible factors, induction of transcriptional repressors, and activation of AMP-activated protein kinase. This review focuses on advances in our understanding of the contribution of β-cell hypoxia to the development of β-cell dysfunction in type 2 diabetes. A better understanding of β-cell hypoxia might be useful in the development of new strategies for treating type 2 diabetes.
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Affiliation(s)
- Kazuya Yamagata
- Department of Medical Biochemistry, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
- Center for Metabolic Regulation of Healthy Aging (CMHA), Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
| | - Tomonori Tsuyama
- Center for Metabolic Regulation of Healthy Aging (CMHA), Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
| | - Yoshifumi Sato
- Department of Medical Biochemistry, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
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2
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Bi J, Zhou W, Tang Z. Pathogenesis of diabetic complications: Exploring hypoxic niche formation and HIF-1α activation. Biomed Pharmacother 2024; 172:116202. [PMID: 38330707 DOI: 10.1016/j.biopha.2024.116202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/10/2024] Open
Abstract
Hypoxia is a common feature of diabetic tissues, which highly correlates to the progression of diabetes. The formation of hypoxic context is induced by disrupted oxygen homeostasis that is predominantly driven by vascular remodeling in diabetes. While different types of vascular impairments have been reported, the specific features and underlying mechanisms are yet to be fully understood. Under hypoxic condition, cells upregulate hypoxia-inducible factor-1α (HIF-1α), an oxygen sensor that coordinates oxygen concentration and cell metabolism under hypoxic conditions. However, diabetic context exploits this machinery for pathogenic functions. Although HIF-1α protects cells from diabetic insult in multiple tissues, it also jeopardizes cell function in the retina. To gain a deeper understanding of hypoxia in diabetic complications, we focus on the formation of tissue hypoxia and the outcomes of HIF-1α dysregulation under diabetic context. Hopefully, this review can provide a better understanding on hypoxia biology in diabetes.
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Affiliation(s)
- Jingjing Bi
- Basic Medicine Research Innovation Center for cardiometabolic diseases, Ministry of Education,Southwest Medical University, Ministry of Education, Southwest Medical University, Luzhou, China
| | - Wenhao Zhou
- Yucebio Technology Co., Ltd., Shenzhen, China
| | - Zonghao Tang
- Basic Medicine Research Innovation Center for cardiometabolic diseases, Ministry of Education,Southwest Medical University, Ministry of Education, Southwest Medical University, Luzhou, China; Baylor College of Medicine, Department of Molecular and Cellular Biology, Houston, TX, USA.
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3
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Hai Y, Ren K, Zhang Y, Yang L, Cao H, Yuan X, Su L, Li H, Feng X, Liu D. HIF-1α serves as a co-linker between AD and T2DM. Biomed Pharmacother 2024; 171:116158. [PMID: 38242039 DOI: 10.1016/j.biopha.2024.116158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 12/27/2023] [Accepted: 01/11/2024] [Indexed: 01/21/2024] Open
Abstract
Alzheimer's disease (AD)-related brain deterioration is linked to the type 2 diabetes mellitus (T2DM) features hyperglycemia, hyperinsulinemia, and insulin resistance. Hypoxia as a common risk factor for both AD and T2DM. Hypoxia-inducible factor-1 alpha (HIF-1α) acts as the main regulator of the hypoxia response and may be a key target in the comorbidity of AD and T2DM. HIF-1α expression is closely related to hyperglycemia, insulin resistance, and inflammation. Tissue oxygen consumption disrupts HIF-1α homeostasis, leading to increased reactive oxygen species levels and the inhibition of insulin receptor pathway activity, causing neuroinflammation, insulin resistance, abnormal Aβ deposition, and tau hyperphosphorylation. HIF-1α activation also leads to the deposition of Aβ by promoting the abnormal shearing of amyloid precursor protein and inhibiting the degradation of Aβ, and it promotes tau hyperphosphorylation by activating oxidative stress and the activation of astrocytes, which further exasperates AD. Therefore, we believe that HIF-α has great potential as a target for the treatment of AD. Importantly, the intracellular homeostasis of HIF-1α is a more crucial factor than its expression level.
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Affiliation(s)
- Yang Hai
- Scientific Research and Experimental Center, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China; Key Laboratory of Dunhuang Medicine, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China.
| | - Ke Ren
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Yarong Zhang
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Lili Yang
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Haoshi Cao
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Xianxia Yuan
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Linling Su
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Hailong Li
- The First Clinical Medical College, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Xiaoli Feng
- Scientific Research and Experimental Center, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China; Key Laboratory of Dunhuang Medicine, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China
| | - Dongling Liu
- School of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, Gansu Province, PR China; Northwest Collaborative Innovation Center for Traditional Chinese Medicine, Lanzhou 730000, Gansu Province, PR China; Gansu Pharmaceutical Industry Innovation Research Institute, Lanzhou 730000, Gansu Province, PR China.
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4
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Puri S, Maachi H, Nair G, Russ HA, Chen R, Pulimeno P, Cutts Z, Ntranos V, Hebrok M. Sox9 regulates alternative splicing and pancreatic beta cell function. Nat Commun 2024; 15:588. [PMID: 38238288 PMCID: PMC10796970 DOI: 10.1038/s41467-023-44384-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 12/12/2023] [Indexed: 01/22/2024] Open
Abstract
Despite significant research, mechanisms underlying the failure of islet beta cells that result in type 2 diabetes (T2D) are still under investigation. Here, we report that Sox9, a transcriptional regulator of pancreas development, also functions in mature beta cells. Our results show that Sox9-depleted rodent beta cells have defective insulin secretion, and aging animals develop glucose intolerance, mimicking the progressive degeneration observed in T2D. Using genome editing in human stem cells, we show that beta cells lacking SOX9 have stunted first-phase insulin secretion. In human and rodent cells, loss of Sox9 disrupts alternative splicing and triggers accumulation of non-functional isoforms of genes with key roles in beta cell function. Sox9 depletion reduces expression of protein-coding splice variants of the serine-rich splicing factor arginine SRSF5, a major splicing enhancer that regulates alternative splicing. Our data highlight the role of SOX9 as a regulator of alternative splicing in mature beta cell function.
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Affiliation(s)
- Sapna Puri
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Minutia Inc., Oakland, CA, USA
| | - Hasna Maachi
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Center for Organoid Systems, Klinikum Rechts der Isar (MRI) and Technical University Munich, 85748, Garching, Germany
- Institute for Diabetes Organoid Technology, Helmholtz Munich, Helmholtz Diabetes Center, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
- Munich Institute of Biomedical Engineering (MIBE), Technical University Munich, Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
| | - Gopika Nair
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Eli Lilly, Indianapolis, IN, USA
| | - Holger A Russ
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Diabetes Institute, University of Florida, Gainesville, FL, USA
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Richard Chen
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Pamela Pulimeno
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Zachary Cutts
- Graduate Program in Bioinformatics, University of California, San Francisco, CA, USA
| | - Vasilis Ntranos
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Matthias Hebrok
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA.
- Center for Organoid Systems, Klinikum Rechts der Isar (MRI) and Technical University Munich, 85748, Garching, Germany.
- Institute for Diabetes Organoid Technology, Helmholtz Munich, Helmholtz Diabetes Center, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
- Munich Institute of Biomedical Engineering (MIBE), Technical University Munich, Munich, Germany.
- German Center for Diabetes Research (DZD), Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany.
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Duvillié B, Jockers R. Editorial: Hypoxia, oxidative stress, and endocrine cancers. Front Endocrinol (Lausanne) 2023; 14:1268268. [PMID: 37908751 PMCID: PMC10614159 DOI: 10.3389/fendo.2023.1268268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/29/2023] [Indexed: 11/02/2023] Open
Affiliation(s)
- Bertrand Duvillié
- Department of Signaling, Radiobiology and Cancer, Institut Curie, Orsay, France
- Inserm U1021, Centre Universitaire, Orsay, France
- CNRS UMR 3347, Centre Universitaire, Orsay, France
- Université Paris-Saclay, Orsay, France
- PSL Research University, Paris, France
| | - Ralf Jockers
- Université Paris Cité, Institut Cochin, Inserm, CNRS, Paris, France
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6
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Tsuyama T, Sato Y, Yoshizawa T, Matsuoka T, Yamagata K. Hypoxia causes pancreatic β-cell dysfunction and impairs insulin secretion by activating the transcriptional repressor BHLHE40. EMBO Rep 2023; 24:e56227. [PMID: 37341148 PMCID: PMC10398664 DOI: 10.15252/embr.202256227] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 05/28/2023] [Accepted: 06/04/2023] [Indexed: 06/22/2023] Open
Abstract
Hypoxia can occur in pancreatic β-cells in type 2 diabetes. Although hypoxia exerts deleterious effects on β-cell function, the associated mechanisms are largely unknown. Here, we show that the transcriptional repressor basic helix-loop-helix family member e40 (BHLHE40) is highly induced in hypoxic mouse and human β-cells and suppresses insulin secretion. Conversely, BHLHE40 deficiency in hypoxic MIN6 cells or β-cells of ob/ob mice reverses defects in insulin secretion. Mechanistically, BHLHE40 represses the expression of Mafa, encoding the transcription factor musculoaponeurotic fibrosarcoma oncogene family A (MAFA), by attenuating the binding of pancreas/duodenum homeobox protein 1 (PDX1) to its enhancer region. Impaired insulin secretion in hypoxic β-cells was recovered by MAFA re-expression. Collectively, our work identifies BHLHE40 as a key hypoxia-induced transcriptional repressor in β-cells that inhibit insulin secretion by suppressing MAFA expression.
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Affiliation(s)
- Tomonori Tsuyama
- Center for Metabolic Regulation of Healthy Aging (CMHA), Faculty of Life SciencesKumamoto UniversityKumamotoJapan
| | - Yoshifumi Sato
- Department of Medical Biochemistry, Faculty of Life SciencesKumamoto UniversityKumamotoJapan
| | - Tatsuya Yoshizawa
- Department of Medical Biochemistry, Faculty of Life SciencesKumamoto UniversityKumamotoJapan
| | - Takaaki Matsuoka
- First Department of Internal MedicineWakayama Medical UniversityWakayamaJapan
| | - Kazuya Yamagata
- Center for Metabolic Regulation of Healthy Aging (CMHA), Faculty of Life SciencesKumamoto UniversityKumamotoJapan
- Department of Medical Biochemistry, Faculty of Life SciencesKumamoto UniversityKumamotoJapan
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7
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Mukai E, Fujimoto S, Inagaki N. Role of Reactive Oxygen Species in Glucose Metabolism Disorder in Diabetic Pancreatic β-Cells. Biomolecules 2022; 12:biom12091228. [PMID: 36139067 PMCID: PMC9496160 DOI: 10.3390/biom12091228] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/28/2022] [Accepted: 08/31/2022] [Indexed: 11/18/2022] Open
Abstract
The dysfunction of pancreatic β-cells plays a central role in the onset and progression of type 2 diabetes mellitus (T2DM). Insulin secretory defects in β-cells are characterized by a selective impairment of glucose stimulation, and a reduction in glucose-induced ATP production, which is essential for insulin secretion. High glucose metabolism for insulin secretion generates reactive oxygen species (ROS) in mitochondria. In addition, the expression of antioxidant enzymes is very low in β-cells. Therefore, β-cells are easily exposed to oxidative stress. In islet studies using a nonobese T2DM animal model that exhibits selective impairment of glucose-induced insulin secretion (GSIS), quenching ROS generated by glucose stimulation and accumulated under glucose toxicity can improve impaired GSIS. Acute ROS generation and toxicity cause glucose metabolism disorders through different molecular mechanisms. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor, is a master regulator of antioxidant defense and a potential therapeutic target in oxidative stress-related diseases, suggesting the possible involvement of Nrf2 in β-cell dysfunction caused by ROS. In this review, we describe the mechanisms of insulin secretory defects induced by oxidative stress in diabetic β-cells.
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Affiliation(s)
- Eri Mukai
- Medical Physiology and Metabolism Laboratory, Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu 5258577, Japan
- Correspondence:
| | - Shimpei Fujimoto
- Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University, Kochi 7838505, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 6068507, Japan
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8
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Abstract
The pancreatic β-cells are essential for regulating glucose homeostasis through the coordinated release of the insulin hormone. Dysfunction of the highly specialized β-cells results in diabetes mellitus, a growing global health epidemic. In this review, we describe the development and function of β-cells the emerging concept of heterogeneity within insulin-producing cells, and the potential of other cell types to assume β-cell functionality via transdifferentiation. We also discuss emerging routes to design cells with minimal β-cell properties and human stem cell differentiation efforts that carry the promise to restore normoglycemia in patients suffering from diabetes.
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Affiliation(s)
- Natanya Kerper
- Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, California 94143, USA
| | - Sudipta Ashe
- Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, California 94143, USA
| | - Matthias Hebrok
- Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, California 94143, USA
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9
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Geng L, Liao B, Jin L, Yu J, Zhao X, Zhao Y, Zhong L, Wang B, Li J, Liu J, Yang JK, Jia W, Lian Q, Xu A. β-Klotho promotes glycolysis and glucose-stimulated insulin secretion via GP130. Nat Metab 2022; 4:608-626. [PMID: 35551509 DOI: 10.1038/s42255-022-00572-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 04/07/2022] [Indexed: 12/13/2022]
Abstract
Impaired glucose-stimulated insulin secretion (GSIS) is a hallmark of type-2 diabetes. However, cellular signaling machineries that control GSIS remain incompletely understood. Here, we report that β-klotho (KLB), a single-pass transmembrane protein known as a co-receptor for fibroblast growth factor 21 (FGF21), fine tunes GSIS via modulation of glycolysis in pancreatic β-cells independent of the actions of FGF21. β-cell-specific deletion of Klb but not Fgf21 deletion causes defective GSIS and glucose intolerance in mice and defective GSIS in islets of type-2 diabetic mice is mitigated by adenovirus-mediated restoration of KLB. Mechanistically, KLB interacts with and stabilizes the cytokine receptor subunit GP130 by blockage of ubiquitin-dependent lysosomal degradation, thereby facilitating interleukin-6-evoked STAT3-HIF1α signaling, which in turn transactivates a cluster of glycolytic genes for adenosine triphosphate production and GSIS. The defective glycolysis and GSIS in Klb-deficient islets are rescued by adenovirus-mediated replenishment of STAT3 or HIF1α. Thus, KLB functions as a key cell-surface regulator of GSIS by coupling the GP130 receptor signaling to glucose catabolism in β-cells and represents a promising therapeutic target for diabetes.
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Affiliation(s)
- Leiluo Geng
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
- Cord Blood Bank, Guangzhou Institute of Eugenics and Perinatology, Guangzhou Women and Children's Medical Centre, Guangzhou Medical University, Guangzhou, China
| | - Boya Liao
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Leigang Jin
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Jiasui Yu
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Xiaoyu Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Yuntao Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
- College of Food Science and Technology, Guangdong Ocean University, Zhanjiang, China
| | - Ling Zhong
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Baile Wang
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Jiufeng Li
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Jie Liu
- Department of Medicine, The University of Hong Kong, Hong Kong, China
- Cord Blood Bank, Guangzhou Institute of Eugenics and Perinatology, Guangzhou Women and Children's Medical Centre, Guangzhou Medical University, Guangzhou, China
| | - Jin-Kui Yang
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Wei Jia
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
- Center for Translational Medicine, Shanghai Key Laboratory of Diabetes Mellitus, and Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - Qizhou Lian
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China.
- Department of Medicine, The University of Hong Kong, Hong Kong, China.
- Cord Blood Bank, Guangzhou Institute of Eugenics and Perinatology, Guangzhou Women and Children's Medical Centre, Guangzhou Medical University, Guangzhou, China.
- HKUMed Laboratory of Cellular Therapeutics, The University of Hong Kong, Hong Kong, China.
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China.
- Department of Medicine, The University of Hong Kong, Hong Kong, China.
- Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China.
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10
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Ilegems E, Bryzgalova G, Correia J, Yesildag B, Berra E, Ruas JL, Pereira TS, Berggren PO. HIF-1α inhibitor PX-478 preserves pancreatic β cell function in diabetes. Sci Transl Med 2022; 14:eaba9112. [PMID: 35353540 DOI: 10.1126/scitranslmed.aba9112] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
During progression of type 2 diabetes, pancreatic β cells are subjected to sustained metabolic overload. We postulated that this state mediates a hypoxic phenotype driven by hypoxia-inducible factor-1α (HIF-1α) and that treatment with the HIF-1α inhibitor PX-478 would improve β cell function. Our studies showed that the HIF-1α protein was present in pancreatic β cells of diabetic mouse models. In mouse islets with high glucose metabolism, the emergence of intracellular Ca2+ oscillations at low glucose concentration and the abnormally high basal release of insulin were suppressed by treatment with the HIF-1α inhibitor PX-478, indicating improvement of β cell function. Treatment of db/db mice with PX-478 prevented the rise of glycemia and diabetes progression by maintenance of elevated plasma insulin concentration. In streptozotocin-induced diabetic mice, PX-478 improved the recovery of glucose homeostasis. Islets isolated from these mice showed hallmarks of improved β cell function including elevation of insulin content, increased expression of genes involved in β cell function and maturity, inhibition of dedifferentiation markers, and formation of mature insulin granules. In response to PX-478 treatment, human islet organoids chronically exposed to high glucose presented improved stimulation index of glucose-induced insulin secretion. These results suggest that the HIF-1α inhibitor PX-478 has the potential to act as an antidiabetic therapeutic agent that preserves β cell function under metabolic overload.
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Affiliation(s)
- Erwin Ilegems
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Galyna Bryzgalova
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Jorge Correia
- Department of Physiology and Pharmacology, Molecular and Cellular Exercise Physiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | | | - Edurne Berra
- Centro de Investigación Cooperativa en Biociencias CIC bioGUNE, 48160 Derio, Spain
| | - Jorge L Ruas
- Department of Physiology and Pharmacology, Molecular and Cellular Exercise Physiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Teresa S Pereira
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden.,Department of Physiology and Pharmacology, Molecular and Cellular Exercise Physiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden.,Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.,Lee Kong Chian School of Medicine, Nanyang Technological University, Novena Campus, 308232 Singapore, Singapore.,School of Biomedical Sciences, Ulster University, BT52 1SA Coleraine, Northern Ireland, UK
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11
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Hoang M, Jentz E, Janssen SM, Nasteska D, Cuozzo F, Hodson DJ, Tupling AR, Fong GH, Joseph JW. Isoform-specific Roles of Prolyl Hydroxylases in the Regulation of Pancreatic β-Cell Function. Endocrinology 2022; 163:6413706. [PMID: 34718519 PMCID: PMC8643417 DOI: 10.1210/endocr/bqab226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Indexed: 11/19/2022]
Abstract
Pancreatic β-cells can secrete insulin via 2 pathways characterized as KATP channel -dependent and -independent. The KATP channel-independent pathway is characterized by a rise in several potential metabolic signaling molecules, including the NADPH/NADP+ ratio and α-ketoglutarate (αKG). Prolyl hydroxylases (PHDs), which belong to the αKG-dependent dioxygenase superfamily, are known to regulate the stability of hypoxia-inducible factor α. In the current study, we assess the role of PHDs in vivo using the pharmacological inhibitor dimethyloxalylglycine (DMOG) and generated β-cell-specific knockout (KO) mice for all 3 isoforms of PHD (β-PHD1 KO, β-PHD2 KO, and β-PHD3 KO mice). DMOG inhibited in vivo insulin secretion in response to glucose challenge and inhibited the first phase of insulin secretion but enhanced the second phase of insulin secretion in isolated islets. None of the β-PHD KO mice showed any significant in vivo defects associated with glucose tolerance and insulin resistance except for β-PHD2 KO mice which had significantly increased plasma insulin during a glucose challenge. Islets from both β-PHD1 KO and β-PHD3 KO had elevated β-cell apoptosis and reduced β-cell mass. Isolated islets from β-PHD1 KO and β-PHD3 KO had impaired glucose-stimulated insulin secretion and glucose-stimulated increases in the ATP/ADP and NADPH/NADP+ ratio. All 3 PHD isoforms are expressed in β-cells, with PHD3 showing the most distinct expression pattern. The lack of each PHD protein did not significantly impair in vivo glucose homeostasis. However, β-PHD1 KO and β-PHD3 KO mice had defective β-cell mass and islet insulin secretion, suggesting that these mice may be predisposed to developing diabetes.
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Affiliation(s)
- Monica Hoang
- School of Pharmacy, University of Waterloo, Kitchener, ON, Canada
| | - Emelien Jentz
- School of Pharmacy, University of Waterloo, Kitchener, ON, Canada
| | - Sarah M Janssen
- School of Pharmacy, University of Waterloo, Kitchener, ON, Canada
| | - Daniela Nasteska
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Federica Cuozzo
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - A Russell Tupling
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Guo-Hua Fong
- Center for Vascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Jamie W Joseph
- School of Pharmacy, University of Waterloo, Kitchener, ON, Canada
- Correspondence: Jamie W. Joseph, PhD, Health Science Campus Building A, Room 4008, University of Waterloo, 10A Victoria Street South, Kitchener, ON, Canada, N2G 1C5.
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12
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Human Islet Amyloid Polypeptide Overexpression in INS-1E Cells Influences Amylin Oligomerization under ER Stress and Oxidative Stress. Int J Mol Sci 2021; 22:ijms222111341. [PMID: 34768769 PMCID: PMC8583535 DOI: 10.3390/ijms222111341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/12/2021] [Accepted: 10/19/2021] [Indexed: 02/07/2023] Open
Abstract
Human amylin or islet amyloid polypeptide (hIAPP) is synthesized in the pancreatic β-cells and has been shown to contribute to the pathogenesis of type 2 diabetes (T2D) in vitro and in vivo. This study compared amylin oligomerization/expression and signal transduction under endoplasmic reticulum (ER) stress and oxidative stress. pCMV-hIAPP-overexpressing INS-1E cells presented different patterns of amylin oligomerization/expression under ER stress and oxidative stress. Amylin oligomerization/expression under ER stress showed three amylin oligomers of less than 15 kDa size in pCMV-hIAPP-overexpressing cells, while one band was detected under oxidative stress. Under ER stress conditions, HIF1α, p-ERK, CHOP, Cu/Zn-SOD, and Bax were significantly increased in pCMV-hIAPP-overexpressing cells compared to the pCMV-Entry-expressing cells (control), whereas p-Akt, p-mTOR, Mn-SOD, catalase, and Bcl-2 were significantly decreased. Under oxidative stress conditions, HIF1α, p-ERK, CHOP, Mn-SOD, catalase, and Bcl-2 were significantly reduced in pCMV-hIAPP-overexpressing cells compared to the control, whereas p-mTOR, Cu/Zn-SOD, and Bax were significantly increased. In mitochondrial oxidative phosphorylation (OXPHOS), the mitochondrial complex I and complex IV were significantly decreased under ER stress conditions and significantly increased under oxidative stress conditions in pCMV-hIAPP-overexpressing cells compared to the control. The present study results demonstrate that amylin undergoes oligomerization under ER stress in pCMV-hIAPP-overexpressing cells. In addition, human amylin overexpression under ER stress in the pancreatic β cells may enhance amylin protein aggregation, resulting in β-cell dysfunction.
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13
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Brown MR, Holmes H, Rakshit K, Javeed N, Her TK, Stiller AA, Sen S, Shull GE, Prakash YS, Romero MF, Matveyenko AV. Electrogenic sodium bicarbonate cotransporter NBCe1 regulates pancreatic β cell function in type 2 diabetes. J Clin Invest 2021; 131:142365. [PMID: 34623331 DOI: 10.1172/jci142365] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 07/22/2021] [Indexed: 12/13/2022] Open
Abstract
Pancreatic β cell failure in type 2 diabetes mellitus (T2DM) is attributed to perturbations of the β cell's transcriptional landscape resulting in impaired glucose-stimulated insulin secretion. Recent studies identified SLC4A4 (a gene encoding an electrogenic Na+-coupled HCO3- cotransporter and intracellular pH regulator, NBCe1) as one of the misexpressed genes in β cells of patients with T2DM. Thus, in the current study, we set out to test the hypothesis that misexpression of SLC4A4/NBCe1 in T2DM β cells contributes to β cell dysfunction and impaired glucose homeostasis. To address this hypothesis, we first confirmed induction of SLC4A4/NBCe1 expression in β cells of patients with T2DM and demonstrated that its expression was associated with loss of β cell transcriptional identity, intracellular alkalinization, and β cell dysfunction. In addition, we generated a β cell-selective Slc4a4/NBCe1-KO mouse model and found that these mice were protected from diet-induced metabolic stress and β cell dysfunction. Importantly, improved glucose tolerance and enhanced β cell function in Slc4a4/NBCe1-deficient mice were due to augmented mitochondrial function and increased expression of genes regulating β cell identity and function. These results suggest that increased β cell expression of SLC4A4/NBCe1 in T2DM plays a contributory role in promotion of β cell failure and should be considered as a potential therapeutic target.
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Affiliation(s)
- Matthew R Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Heather Holmes
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Kuntol Rakshit
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Naureen Javeed
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Tracy K Her
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Alison A Stiller
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Satish Sen
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Gary E Shull
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Y S Prakash
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.,Department of Anesthesiology
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.,Division of Nephrology and Hypertension and
| | - Aleksey V Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.,Division of Endocrinology, Metabolism, Diabetes, and Nutrition, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
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14
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Durrani IA, Bhatti A, John P. The prognostic outcome of 'type 2 diabetes mellitus and breast cancer' association pivots on hypoxia-hyperglycemia axis. Cancer Cell Int 2021; 21:351. [PMID: 34225729 PMCID: PMC8259382 DOI: 10.1186/s12935-021-02040-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 06/24/2021] [Indexed: 12/24/2022] Open
Abstract
Type 2 diabetes mellitus and breast cancer are complex, chronic, heterogeneous, and multi-factorial diseases; with common risk factors including but not limited to diet, obesity, and age. They also share mutually inclusive phenotypic features such as the metabolic deregulations resulting from hyperglycemia, hypoxic conditions and hormonal imbalances. Although, the association between diabetes and cancer has long been speculated; however, the exact molecular nature of this link remains to be fully elucidated. Both the diseases are leading causes of death worldwide and a causal relationship between the two if not addressed, may translate into a major global health concern. Previous studies have hypothesized hyperglycemia, hyperinsulinemia, hormonal imbalances and chronic inflammation, as some of the possible grounds for explaining how diabetes may lead to cancer initiation, yet further research still needs to be done to validate these proposed mechanisms. At the crux of this dilemma, hyperglycemia and hypoxia are two intimately related states involving an intricate level of crosstalk and hypoxia inducible factor 1, at the center of this, plays a key role in mediating an aggressive disease state, particularly in solid tumors such as breast cancer. Subsequently, elucidating the role of HIF1 in establishing the diabetes-breast cancer link on hypoxia-hyperglycemia axis may not only provide an insight into the molecular mechanisms underlying the association but also, illuminate on the prognostic outcome of the therapeutic targeting of HIF1 signaling in diabetic patients with breast cancer or vice versa. Hence, this review highlights the critical role of HIF1 signaling in patients with both T2DM and breast cancer, potentiates its significance as a prognostic marker in comorbid patients, and further discusses the potential prognostic outcome of targeting HIF1, subsequently establishing the pressing need for HIF1 molecular profiling-based patient selection leading to more effective therapeutic strategies emerging from personalized medicine.
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Affiliation(s)
- Ilhaam Ayaz Durrani
- Atta-ur-Rehman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, Islamabad, Pakistan
| | - Attya Bhatti
- Atta-ur-Rehman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, Islamabad, Pakistan.
| | - Peter John
- Atta-ur-Rehman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, Islamabad, Pakistan
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15
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Abstract
Hypoxia-inducible factors (HIFs) are the key regulators of oxygen homeostasis in response to hypoxia. In diabetes, multiple tissues are hypoxic but adaptive responses to hypoxia are impaired due to insufficient activation of HIF signalling, which results from inhibition of HIF-1α stability and function due to hyperglycaemia and elevated fatty acid levels. In this review, we will summarise and discuss current findings about the regulation of HIF signalling in diabetes and the pathogenic roles of hypoxia and dysregulated HIF signalling in the development of diabetes and its complications. The therapeutic potential of targeting HIF signalling for the prevention and treatment of diabetes and related complications is also discussed.
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Affiliation(s)
- Sergiu-Bogdan Catrina
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
- Department of Endocrinology and Diabetes, Karolinska University Hospital, Stockholm, Sweden.
- Center for Diabetes, Academic Specialist Centrum, Stockholm, Sweden.
| | - Xiaowei Zheng
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
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16
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Abstract
Hypoxia can be defined as a relative deficiency in the amount of oxygen reaching the tissues. Hypoxia-inducible factors (HIFs) are critical regulators of the mammalian response to hypoxia. In normal circumstances, HIF-1α protein turnover is rapid, and hyperglycemia further destabilizes the protein. In addition to their role in diabetes pathogenesis, HIFs are implicated in development of the microvascular and macrovascular complications of diabetes. Improving glucose control in people with diabetes increases HIF-1α protein and has wide-ranging benefits, some of which are at least partially mediated by HIF-1α. Nevertheless, most strategies to improve diabetes or its complications via regulation of HIF-1α have not currently proven to be clinically useful. The intersection of HIF biology with diabetes is a complex area in which many further questions remain, especially regarding the well-conducted studies clearly describing discrepant effects of different methods of increasing HIF-1α, even within the same tissues. This Review presents a brief overview of HIFs; discusses the range of evidence implicating HIFs in β cell dysfunction, diabetes pathogenesis, and diabetes complications; and examines the differing outcomes of HIF-targeting approaches in these conditions.
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Affiliation(s)
- Jenny E Gunton
- Centre for Diabetes, Obesity and Endocrinology, Westmead Institute for Medical Research, Westmead, New South Wales, Australia.,Westmead Hospital, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
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17
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Abstract
Anaplerosis and the associated mitochondrial metabolite transporters generate unique cytosolic metabolic signaling molecules that can regulate insulin release from pancreatic β-cells. It has been shown that mitochondrial metabolites, transported by the citrate carrier (CIC), dicarboxylate carrier (DIC), oxoglutarate carrier (OGC), and mitochondrial pyruvate carrier (MPC) play a vital role in the regulation of glucose-stimulated insulin secretion (GSIS). Metabolomic studies on static and biphasic insulin secretion, suggests that several anaplerotic derived metabolites, including α-ketoglutarate (αKG), are strongly associated with nutrient regulated insulin secretion. Support for a role of αKG in the regulation of insulin secretion comes from studies looking at αKG dependent enzymes, including hypoxia-inducible factor-prolyl hydroxylases (PHDs) in clonal β-cells, and rodent and human islets. This review will focus on the possible link between defective anaplerotic-derived αKG, PHDs, and the development of type 2 diabetes (T2D).
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Affiliation(s)
- M. Hoang
- School of Pharmacy, University of Waterloo, Kitchener, Ontario, Canada
| | - J. W. Joseph
- School of Pharmacy, University of Waterloo, Kitchener, Ontario, Canada
- CONTACT J. W. Joseph School of Pharmacy, University of Waterloo, Kitchener, ONN2G1C5, Canada
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18
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The control of acidity in tumor cells: a biophysical model. Sci Rep 2020; 10:13613. [PMID: 32788634 PMCID: PMC7423962 DOI: 10.1038/s41598-020-70396-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 07/28/2020] [Indexed: 01/02/2023] Open
Abstract
Acidosis of the tumor microenvironment leads to cancer invasion, progression and resistance to therapies. We present a biophysical model that describes how tumor cells regulate intracellular and extracellular acidity while they grow in a microenvironment characterized by increasing acidity and hypoxia. The model takes into account the dynamic interplay between glucose and \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {O}_2$$\end{document}O2 consumption with lactate and \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {CO}_2$$\end{document}CO2 production and connects these processes to \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {H}^+$$\end{document}H+ and \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {HCO}_3^-$$\end{document}HCO3- fluxes inside and outside cells. We have validated the model with independent experimental data and used it to investigate how and to which extent tumor cells can survive in adverse micro-environments characterized by acidity and hypoxia. The simulations show a dominance of the \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {H}^+$$\end{document}H+ exchanges in well-oxygenated regions, and of \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {HCO}_3^-$$\end{document}HCO3- exchanges in the inner hypoxic regions where tumor cells are known to acquire malignant phenotypes. The model also includes the activity of the enzyme Carbonic Anhydrase 9 (CA9), a known marker of tumor aggressiveness, and the simulations demonstrate that CA9 acts as a nonlinear \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {pH}_i$$\end{document}pHi equalizer at any \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {O}_2$$\end{document}O2 level in cells that grow in acidic extracellular environments.
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19
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Hanschmann EM, Petry SF, Eitner S, Maresch CC, Lingwal N, Lillig CH, Linn T. Paracrine regulation and improvement of β-cell function by thioredoxin. Redox Biol 2020; 34:101570. [PMID: 32473461 PMCID: PMC7260591 DOI: 10.1016/j.redox.2020.101570] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022] Open
Abstract
The failure of insulin-producing β-cells is the underlying cause of hyperglycemia in diabetes mellitus. β-cell decay has been linked to hypoxia, chronic inflammation, and oxidative stress. Thioredoxin (Trx) proteins are major actors in redox signaling and essential for signal transduction and the cellular stress response. We have analyzed the cytosolic, mitochondrial, and extracellular Trx system proteins in hypoxic and cytokine-induced stress using β-cell culture, isolated pancreatic islets, and pancreatic islet transplantation modelling low oxygen supply. Protein levels of cytosolic Trx1 and Trx reductase (TrxR) 1 significantly decreased, while mitochondrial Trx2 and TrxR2 increased upon hypoxia and reoxygenation. Interestingly, Trx1 was secreted by β-cells during hypoxia. Moreover, murine and human pancreatic islet grafts released Trx1 upon glucose stimulation. Survival of transplanted islets was substantially impaired by the TrxR inhibitor auranofin. Since a release was prominent upon hypoxia, putative paracrine effects of Trx1 on β-cells were examined. In fact, exogenously added recombinant hTrx1 mitigated apoptosis and preserved glucose sensitivity in pancreatic islets subjected to hypoxia and inflammatory stimuli, dependent on its redox activity. Human subjects were studied, demonstrating a transient increase in extracellular Trx1 in serum after glucose challenge. This increase correlated with better pancreatic islet function. Moreover, hTrx1 inhibited the migration of primary murine macrophages. In conclusion, our study offers evidence for paracrine functions of extracellular Trx1 that improve the survival and function of pancreatic β-cells.
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Affiliation(s)
- Eva-Maria Hanschmann
- Institute for Medical Biochemistry and Molecular Biology, University Medicine, University of Greifswald, Germany; Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | | | - Susanne Eitner
- Institute for Medical Biochemistry and Molecular Biology, University Medicine, University of Greifswald, Germany
| | | | - Neelam Lingwal
- Clinical Research Unit, Center of Internal Medicine, Justus-Liebig-University, Giessen, Germany
| | - Christopher Horst Lillig
- Institute for Medical Biochemistry and Molecular Biology, University Medicine, University of Greifswald, Germany.
| | - Thomas Linn
- Clinical Research Unit, Center of Internal Medicine, Justus-Liebig-University, Giessen, Germany.
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20
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IAPP toxicity activates HIF1α/PFKFB3 signaling delaying β-cell loss at the expense of β-cell function. Nat Commun 2019; 10:2679. [PMID: 31213603 PMCID: PMC6581914 DOI: 10.1038/s41467-019-10444-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 05/13/2019] [Indexed: 02/07/2023] Open
Abstract
The islet in type 2 diabetes (T2D) is characterized by amyloid deposits derived from islet amyloid polypeptide (IAPP), a protein co-expressed with insulin by β-cells. In common with amyloidogenic proteins implicated in neurodegeneration, human IAPP (hIAPP) forms membrane permeant toxic oligomers implicated in misfolded protein stress. Here, we establish that hIAPP misfolded protein stress activates HIF1α/PFKFB3 signaling, this increases glycolysis disengaged from oxidative phosphorylation with mitochondrial fragmentation and perinuclear clustering, considered a protective posture against increased cytosolic Ca2+ characteristic of toxic oligomer stress. In contrast to tissues with the capacity to regenerate, β-cells in adult humans are minimally replicative, and therefore fail to execute the second pro-regenerative phase of the HIF1α/PFKFB3 injury pathway. Instead, β-cells in T2D remain trapped in the pro-survival first phase of the HIF1α injury repair response with metabolism and the mitochondrial network adapted to slow the rate of cell attrition at the expense of β-cell function. Type 2 diabetes is associated with islet amyloid deposits derived from islet amyloid polypeptide (IAPP) expressed by β-cells. Here the authors show that IAPP misfolded protein stress induces the hypoxia inducible factor 1 alpha injury repair pathway and activates survival metabolic changes mediated by PFKFB3.
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21
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Wang M, Hu J, Yan L, Yang Y, He M, Wu M, Li Q, Gong W, Yang Y, Wang Y, Handy DE, Lu B, Hao C, Wang Q, Li Y, Hu R, Stanton RC, Zhang Z. High glucose-induced ubiquitination of G6PD leads to the injury of podocytes. FASEB J 2019; 33:6296-6310. [PMID: 30785802 DOI: 10.1096/fj.201801921r] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Oxidative stress contributes substantially to podocyte injury, which plays an important role in the development of diabetic kidney disease. The mechanism of hyperglycemia-induced oxidative stress in podocytes is not fully understood. Glucose-6-phosphate dehydrogenase (G6PD) is critical in maintaining NADPH, which is an important cofactor for the antioxidant system. Here, we hypothesized that high glucose induced ubiquitination and degradation of G6PD, which injured podocytes by reactive oxygen species (ROS) accumulation. We found that G6PD protein expression was decreased in kidneys of both diabetic patients and diabetic rodents. G6PD activity was also reduced in diabetic mice. Overexpressing G6PD reversed redox imbalance and podocyte apoptosis induced by high glucose and palmitate. Inhibition of G6PD with small interfering RNA induced podocyte apoptosis. In kidneys of G6PD-deficient mice, podocyte apoptosis was significantly increased. Interestingly, high glucose had no effect on G6PD mRNA expression. Decreased G6PD protein expression was mediated by the ubiquitin proteasome pathway. We found that the von Hippel-Lindau (VHL) protein, an E3 ubiquitin ligase subunit, directly bound to G6PD and degraded G6PD through ubiquitylating G6PD on K366 and K403. In summary, our data suggest that high glucose induces ubiquitination of G6PD by VHL E3 ubiquitin ligase, which leads to ROS accumulation and podocyte injury.-Wang, M., Hu, J., Yan, L., Yang, Y., He, M., Wu, M., Li, Q., Gong, W., Yang, Y., Wang, Y., Handy, D. E., Lu, B., Hao, C., Wang, Q., Li, Y., Hu, R., Stanton, R. C., Zhang, Z. High glucose-induced ubiquitination of G6PD leads to the injury of podocytes.
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Affiliation(s)
- Meng Wang
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Ji Hu
- Department of Endocrinology, The Second Affiliated Hospital, Soochow University, Suzhou, China
| | - Linling Yan
- Department of Endocrinology, The First People's Hospital of Taicang, Suzhou, China
| | - Yeping Yang
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Min He
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Meng Wu
- Department of Endocrinology, The Second Affiliated Hospital, Soochow University, Suzhou, China
| | - Qin Li
- Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Wei Gong
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Yang Yang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Shanghai, China
| | - Yi Wang
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Diane E Handy
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Bin Lu
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Chuanming Hao
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
| | - Qinghua Wang
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China.,Division of Endocrinology and Metabolism, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Yiming Li
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Ronggui Hu
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Shanghai, China
| | - Robert C Stanton
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Zhaoyun Zhang
- Division of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
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22
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Abstract
Hypoxia inducible factors (HIFs) are critical regulators of the response to oxygen deficiency by activating target genes involved in a variety of biological functions. HIFs have been implicated in the pathophysiology of numerous pathologies including cancer. Patients with mutations in the von Hippel-Lindau (VHL) gene, an essential regulator of HIF activity, develop tumors in several organs including the pancreas. Previous functional studies of HIF activation in the pancreas have used Vhlh (the murine homolog of VHL) deficient mice. However, the role of each specific HIF transcription factors in the pancreas has not been thoroughly examined. We derived mice that constitutively express a normoxia-stable form of HIF2α in the pancreas. Activation of HIF2α in the pancreas severely impairs postnatal exocrine pancreas. Mice with pancreas-specific activation of HIF2α develop histological features reminiscent of pancreatitis including loss of acinar cells, ductal dilation and fibrosis. Moreover, we provide evidence that signaling pathways important for acinar cell homeostasis are altered in HIF2α-overexpressing pancreata.
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23
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Chung JO, Park SY, Cho DH, Chung DJ, Chung MY. Anemia is inversely associated with serum C-peptide concentrations in individuals with type 2 diabetes. Medicine (Baltimore) 2018; 97:e11783. [PMID: 30095635 PMCID: PMC6133397 DOI: 10.1097/md.0000000000011783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The purpose of the study was to test the hypothesis that anemia is related with serum C-peptide concentrations in individuals with type 2 diabetes mellitus (DM).This cross-sectional study was carried out in 1300 individuals with type 2 DM. We measured fasting C-peptide, 2-hour postprandial C-peptide, and postprandial C-peptide minus fasting C-peptide (ΔC-peptide) concentrations. Anemia was defined as hemoglobin (Hb) concentrations <130 g/L in men and <120 g/L in women. Anemia was graded into 2 groups: grade I anemia of Hb concentrations ≥110 g/L and grade II anemia of Hb concentrations <110 g/L.Fasting C-peptide, postprandial C-peptide, and ΔC-peptide concentrations were lower in individuals with anemia. According to the grade of anemia, the average C-peptide concentrations differed significantly after adjusting for other covariates. In the multivariable model, the statistically significant relation between anemia and serum C-peptide concentrations remained after adjusting for confounders, including age, gender, family history of diabetes, body mass index, duration of diabetes, glycated Hb, free fatty acids, hypertension, and hyperlipidemia (fasting C-peptide concentration: β = -0.057, P = .032; postprandial C-peptide concentration: β = -0.098, P < .001; ΔC-peptide concentration: β = -0.095, P < .001).Anemia was inversely associated with serum C-peptide concentrations in individuals with type 2 DM.
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Affiliation(s)
| | - Seon-Young Park
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Chonnam National University Medical School, Dong-Gu, Gwangju, Republic of Korea
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24
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Villamayor L, Rodríguez-Seguel E, Araujo R, Carrasco M, Bru-Tarí E, Mellado-Gil JM, Gauthier BR, Martinelli P, Quesada I, Soria B, Martín F, Cano DA, Rojas A. GATA6 Controls Insulin Biosynthesis and Secretion in Adult β-Cells. Diabetes 2018; 67:448-460. [PMID: 29263149 DOI: 10.2337/db17-0364] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 12/13/2017] [Indexed: 11/13/2022]
Abstract
GATA4 and GATA6 play essential, but redundant, roles in pancreas formation in mice, and GATA6 mutations cause pancreatic agenesis in humans. GATA6 mutations have also recently been linked to adult-onset diabetes, with subclinical or no exocrine insufficiency, suggesting an important role for GATA6 in human β-cell physiology. To investigate the role of GATA6 in the adult endocrine pancreas, we generated mice in which Gata6 is specifically inactivated in the pancreas. These mice develop glucose intolerance. Islets deficient in GATA6 activity display decreased insulin content and impaired insulin secretion. Gata6-deficient β-cells exhibit ultrastructural abnormalities, including increased immature insulin granules, swollen mitochondria, and disorganized endoplasmic reticulum. We also demonstrate that Pdx1 expression in adult β-cells depends on GATA sites in transgenic reporter mice and that loss of GATA6 greatly affects β-cell-specific gene expression. These findings demonstrate the essential role of GATA6 in β-cell function.
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Affiliation(s)
- Laura Villamayor
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | - Elisa Rodríguez-Seguel
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | - Raquel Araujo
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Manuel Carrasco
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | | | - José Manuel Mellado-Gil
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | - Benoit R Gauthier
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
| | - Paola Martinelli
- Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain
- Institute for Cancer Research, Medical University of Vienna, Vienna, Austria
| | - Iván Quesada
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
- Universidad Miguel Hernández, Elche, Spain
| | - Bernat Soria
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Franz Martín
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - David A Cano
- Unidad de Gestión de Endocrinología y Nutrición, Instituto de Biomedicina de Sevilla (IBiS), Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Hospital Universitario Virgen del Rocío, Seville, Spain
| | - Anabel Rojas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
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25
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Puri S, Roy N, Russ HA, Leonhardt L, French EK, Roy R, Bengtsson H, Scott DK, Stewart AF, Hebrok M. Replication confers β cell immaturity. Nat Commun 2018; 9:485. [PMID: 29396395 PMCID: PMC5797102 DOI: 10.1038/s41467-018-02939-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 01/09/2018] [Indexed: 02/06/2023] Open
Abstract
Pancreatic β cells are highly specialized to regulate systemic glucose levels by secreting insulin. In adults, increase in β-cell mass is limited due to brakes on cell replication. In contrast, proliferation is robust in neonatal β cells that are functionally immature as defined by a lower set point for glucose-stimulated insulin secretion. Here we show that β-cell proliferation and immaturity are linked by tuning expression of physiologically relevant, non-oncogenic levels of c-Myc. Adult β cells induced to replicate adopt gene expression and metabolic profiles resembling those of immature neonatal β that proliferate readily. We directly demonstrate that priming insulin-producing cells to enter the cell cycle promotes a functionally immature phenotype. We suggest that there exists a balance between mature functionality and the ability to expand, as the phenotypic state of the β cell reverts to a less functional one in response to proliferative cues. Adult beta cells, which are highly specialised insulin-secreting cells, rarely replicate. Puri et al. demonstrate that beta cell proliferative capacity is inversely correlated with their functionality and differentiation state, by inducing proliferation of adult cells with ectopic overexpression of the cell cycle regulator c-Myc.
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Affiliation(s)
- Sapna Puri
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Nilotpal Roy
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Holger A Russ
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA.,Barbara Davis Center for Diabetes, University of Colorado, Anschutz Medical Campus, Denver, CO, USA
| | - Laura Leonhardt
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Esra K French
- Department of Endocrinology, Diabetes and Metabolism, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ritu Roy
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
| | - Henrik Bengtsson
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
| | - Donald K Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Andrew F Stewart
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Matthias Hebrok
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA.
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26
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Chen YF, Pandey S, Day CH, Chen YF, Jiang AZ, Ho TJ, Chen RJ, Padma VV, Kuo WW, Huang CY. Synergistic effect of HIF-1α and FoxO3a trigger cardiomyocyte apoptosis under hyperglycemic ischemia condition. J Cell Physiol 2017; 233:3660-3671. [PMID: 29030976 DOI: 10.1002/jcp.26235] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 09/29/2017] [Indexed: 01/19/2023]
Abstract
Cardiomyocyte death is an important pathogenic feature of ischemia and heart failure. Through this study, we showed the synergistic role of HIF-1α and FoxO3a in cardiomyocyte apoptosis subjected to hypoxia plus elevated glucose levels. Using gene specific small interfering RNAs (siRNA), semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR), Western blot, immunofluorescence, nuclear and cytosolic localization and TUNEL assay techniques, we determined that combined function of HIF-1α and FoxO3a under high glucose plus hypoxia condition lead to enhanced expression of BNIP3 inducing cardiomyocyte death. Our results highlighted the importance of the synergistic role of HIF-1α and FoxO3a in cardiomyocyte death which may add insight into therapeutic approaches to pathophysiology associated with ischemic diabetic cardiomyopathies.
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Affiliation(s)
- Ya-Fang Chen
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan.,Department of Obstetrics and Gynecology, Taichung Veteran's General Hospital, Taichung, Taiwan
| | - Sudhir Pandey
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan
| | | | - Yu-Feng Chen
- Section of Cardiology, Yuan Rung Hospital, Yuanlin, Taiwan
| | - Ai-Zhi Jiang
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan
| | - Tsung-Jung Ho
- School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
| | - Ray-Jade Chen
- Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Vijaya V Padma
- Department of Biotechnology, Bharathiar University, Coimbatore, India
| | - Wei-Wen Kuo
- Department of Biological Science and Technology, China Medical University, Taichung, Taiwan
| | - Chih-Yang Huang
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan.,School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan.,Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, Ho Chi Minh City, Vietnam.,Department of Biological Science and Technology, Asia University, Taichung, Taiwan
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27
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Gupta D, Jetton TL, LaRock K, Monga N, Satish B, Lausier J, Peshavaria M, Leahy JL. Temporal characterization of β cell-adaptive and -maladaptive mechanisms during chronic high-fat feeding in C57BL/6NTac mice. J Biol Chem 2017; 292:12449-12459. [PMID: 28487366 DOI: 10.1074/jbc.m117.781047] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/29/2017] [Indexed: 12/18/2022] Open
Abstract
The onset of type 2 diabetes is characterized by transition from successful to failed insulin secretory compensation to obesity-related insulin resistance and dysmetabolism. Energy-rich diets in rodents are commonly studied models of compensatory increases in both insulin secretion and β cell mass. However, the mechanisms of these adaptive responses are incompletely understood, and it is also unclear why these responses eventually fail. We measured the temporal trends of glucose homeostasis, insulin secretion, β cell morphometry, and islet gene expression in C57BL/6NTac mice fed a 60% high-fat diet (HFD) or control diet for up to 16 weeks. A 2-fold increased hyperinsulinemia was maintained for the first 4 weeks of HFD feeding and then further increased through 16 weeks. β cell mass increased progressively starting at 4 weeks, principally through nonproliferative growth. Insulin sensitivity was not significantly perturbed until 11 weeks of HFD feeding. Over the first 8 weeks, we observed two distinct waves of increased expression of β cell functional and prodifferentiation genes. This was followed by activation of the unfolded protein response at 8 weeks and overt β cell endoplasmic reticulum stress at 12-16 weeks. In summary, β cell adaptation to an HFD in C57BL/6NTac mice entails early insulin hypersecretion and a robust growth phase along with hyperexpression of related genes that begin well before the onset of observed insulin resistance. However, continued HFD exposure results in cessation of gene hyperexpression, β cell functional failure, and endoplasmic reticulum stress. These data point to a complex but not sustainable integration of β cell-adaptive responses to nutrient overabundance, obesity development, and insulin resistance.
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Affiliation(s)
- Dhananjay Gupta
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Thomas L Jetton
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Kyla LaRock
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Navjot Monga
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Basanthi Satish
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - James Lausier
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Mina Peshavaria
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Jack L Leahy
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446.
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28
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Gerber PA, Rutter GA. The Role of Oxidative Stress and Hypoxia in Pancreatic Beta-Cell Dysfunction in Diabetes Mellitus. Antioxid Redox Signal 2017; 26:501-518. [PMID: 27225690 PMCID: PMC5372767 DOI: 10.1089/ars.2016.6755] [Citation(s) in RCA: 385] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 05/25/2016] [Indexed: 12/16/2022]
Abstract
SIGNIFICANCE Metabolic syndrome is a frequent precursor of type 2 diabetes mellitus (T2D), a disease that currently affects ∼8% of the adult population worldwide. Pancreatic beta-cell dysfunction and loss are central to the disease process, although understanding of the underlying molecular mechanisms is still fragmentary. Recent Advances: Oversupply of nutrients, including glucose and fatty acids, and the subsequent overstimulation of beta cells, are believed to be an important contributor to insulin secretory failure in T2D. Hypoxia has also recently been implicated in beta-cell damage. Accumulating evidence points to a role for oxidative stress in both processes. Although the production of reactive oxygen species (ROS) results from enhanced mitochondrial respiration during stimulation with glucose and other fuels, the expression of antioxidant defense genes is unusually low (or disallowed) in beta cells. CRITICAL ISSUES Not all subjects with metabolic syndrome and hyperglycemia go on to develop full-blown diabetes, implying an important role in disease risk for gene-environment interactions. Possession of common risk alleles at the SLC30A8 locus, encoding the beta-cell granule zinc transporter ZnT8, may affect cytosolic Zn2+ concentrations and thus susceptibility to hypoxia and oxidative stress. FUTURE DIRECTIONS Loss of normal beta-cell function, rather than total mass, is increasingly considered to be the major driver for impaired insulin secretion in diabetes. Better understanding of the role of oxidative changes, its modulation by genes involved in disease risk, and effects on beta-cell identity may facilitate the development of new therapeutic strategies to this disease. Antioxid. Redox Signal. 26, 501-518.
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Affiliation(s)
- Philipp A. Gerber
- Department of Endocrinology, Diabetes and Clinical Nutrition, University Hospital Zurich, Zurich, Switzerland
| | - Guy A. Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, United Kingdom
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29
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Huang M, Paglialunga S, Wong JMK, Hoang M, Pillai R, Joseph JW. Role of prolyl hydroxylase domain proteins in the regulation of insulin secretion. Physiol Rep 2016; 4:4/5/e12722. [PMID: 26997627 PMCID: PMC4823601 DOI: 10.14814/phy2.12722] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Type 2 diabetes is associated with impaired nutrient‐regulated anaplerosis and insulin secretion in pancreatic β‐cells. One key anaplerotic substrate that may be involved in regulating insulin release is α‐ketoglutarate (αKG). Since prolyl hydroxylase domain proteins (PHDs) can metabolize cytosolic αKG, we sought to explore the role of this enzyme in the regulation of β‐cell function. The oxygen‐sensing PHDs regulate the stability of hypoxia‐inducible factor 1α (HIF1α) as well as other proline‐containing proteins by catalyzing the hydroxylation of proline residues. This reaction is dependent on sufficient levels of oxygen, iron, and αKG. In the present study, we utilized both pharmacological and genetic approaches to assess the impact of inhibiting PHD activity on β‐cell function. We demonstrate that ethyl‐3,4‐dihydroxybenzoate (EDHB), a PHD inhibitor, significantly blunted glucose‐stimulated insulin secretion (GSIS) from 832/13 clonal cells, rat, and human islets. EDHB reduced glucose utilization, ATP/ADP ratio, and key TCA cycle intermediates such as pyruvate, citrate, fumarate, and malate. siRNA‐mediated knockdown of PHD1 and PHD3 inhibited GSIS, whereas siRNA‐mediated knockdown of PHD2 had no effect on GSIS. Taken together, the current results demonstrate an important role for PHDs as mediators of islet insulin secretion.
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Affiliation(s)
- Mei Huang
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Julia M-K Wong
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
| | - Monica Hoang
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
| | - Renjitha Pillai
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
| | - Jamie W Joseph
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
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30
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Lecomte MJ, Pechberty S, Machado C, Da Barroca S, Ravassard P, Scharfmann R, Czernichow P, Duvillié B. Aggregation of Engineered Human β-Cells Into Pseudoislets: Insulin Secretion and Gene Expression Profile in Normoxic and Hypoxic Milieu. CELL MEDICINE 2016; 8:99-112. [PMID: 28003935 DOI: 10.3727/215517916x692843] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Innovative treatments to cure type 1 diabetes are being actively researched. Among the different strategies, the replacement of β-cells has given promising results. Classically, islets from cadaveric donors are transplanted into diabetic patients, but recently phase I clinical trials that use stem cell-derived β-cells have been started. Such protocols require either an immunosuppressive treatment or the macroencapsulation of the β-cells. They involve cell aggregation and the exposure of the cells to hypoxia. Using an engineered human β-cell, we have addressed these two problems: a novel human β-cell line called EndoC-βH3 was cultured as single cells or aggregated clusters. EndoC-βH3 cells were also cultured at normal atmospheric oxygen tension (pO2 = 21%) or hypoxia (pO2 = 3%) in the presence or absence of modulators of the hypoxia-inducible factor 1α (HIF1α) pathway. Cell aggregation improved glucose-stimulated insulin secretion, demonstrating the benefit of cell-cell contacts. Low oxygen tension decreased β-cell viability and their sensitivity to glucose, but did not alter insulin production nor the insulin secretion capacity of the remaining cells. To investigate the role of HIF1α, we first used a HIF stabilizer at pO2 = 21%. This led to a mild decrease in cell viability, impaired glucose sensitivity, and altered insulin secretion. Finally, we used a HIF inhibitor on EndoC-βH3 pseudoislets exposed to hypoxia. Such treatment considerably decreased cell viability. In conclusion, aggregation of the EndoC-βH3 cells seems to be important to improve their function. A fraction of the EndoC-βH3 cells are resistant to hypoxia, depending on the level of activity of HIF1α. Thus, these cells represent a good human cell model for future investigations on islet cell transplantation analysis.
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Affiliation(s)
- Marie-José Lecomte
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Séverine Pechberty
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Cécile Machado
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Sandra Da Barroca
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Philippe Ravassard
- † Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Institut du cerveau et de la moelle (ICM)-Hôpital Pitié-Salpêtrière , Paris , France
| | - Raphaël Scharfmann
- ‡INSERM U1016, Institut Cochin, Paris, France; §Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | - Paul Czernichow
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Bertrand Duvillié
- ‡INSERM U1016, Institut Cochin, Paris, France; §Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
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31
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Life and death of β cells in Type 1 diabetes: A comprehensive review. J Autoimmun 2016; 71:51-8. [PMID: 27017348 DOI: 10.1016/j.jaut.2016.02.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 01/31/2016] [Accepted: 02/01/2016] [Indexed: 01/03/2023]
Abstract
Type 1 diabetes (T1D) is an autoimmune disorder characterized by the destruction of insulin-producing pancreatic β cells. Immune modulators have achieved some success in modifying the course of disease progression in T1D. However, there are parallel declines in C-peptide levels in treated and control groups after initial responses. In this review, we discuss mechanisms of β cell death in T1D that involve necrosis and apoptosis. New technologies are being developed to enable visualization of insulitis and β cell mass involving positron emission transmission that identifies β cell ligands and magnetic resonance imaging that can identify vascular leakage. Molecular signatures that identify β cell derived insulin DNA that is released from dying cells have been described and applied to clinical settings. We also consider changes in β cells that occur during disease progression including the induction of DNA methyltransferases that may affect the function and differentiation of β cells. Our findings from newer data suggest that the model of chronic long standing β cell killing should be reconsidered. These studies indicate that the pathophysiology is accelerated in the peridiagnosis period and manifest by increased rates of β cell killing and insulin secretory impairments over a shorter period than previously thought. Finally, we consider cellular explanations to account for the ongoing loss of insulin production despite continued immune therapy that may identify potential targets for treatment. The progressive decline in β cell function raises the question as to whether β cell failure that is independent of immune attack may be involved.
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Suzuki K, Sato Y, Kai S, Nishi K, Adachi T, Matsuo Y, Hirota K. Volatile anesthetics suppress glucose-stimulated insulin secretion in MIN6 cells by inhibiting glucose-induced activation of hypoxia-inducible factor 1. PeerJ 2015; 3:e1498. [PMID: 26713247 PMCID: PMC4690348 DOI: 10.7717/peerj.1498] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 11/23/2015] [Indexed: 12/23/2022] Open
Abstract
Proper glycemic control is one of the most important goals in perioperative patient management. Insulin secretion from pancreatic β-cells in response to an increased blood glucose concentration plays the most critical role in glycemic control. Several animal and human studies have indicated that volatile anesthetics impair glucose-stimulated insulin secretion (GSIS). A convincing GSIS model has been established, in which the activity of ATP-dependent potassium channels (KATP) under the control of intracellular ATP plays a critical role. We previously reported that pimonidazole adduct formation and stabilization of hypoxia-inducible factor-1α (HIF-1α) were detected in response to glucose stimulation and that MIN6 cells overexpressing HIF-1α were resistant to glucose-induced hypoxia. Genetic ablation of HIF-1α or HIF-1β significantly inhibited GSIS in mice. Moreover, we previously reported that volatile anesthetics suppressed hypoxia-induced HIF activation in vitro and in vivo.To examine the direct effect of volatile anesthetics on GSIS, we used the MIN6 cell line, derived from mouse pancreatic β-cells. We performed a series of experiments to examine the effects of volatile anesthetics (sevoflurane and isoflurane) on GSIS and demonstrated that these compounds inhibited the glucose-induced ATP increase, which is dependent on intracellular hypoxia-induced HIF-1 activity, and suppressed GSIS at a clinically relevant dose in these cells.
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Affiliation(s)
- Kengo Suzuki
- Department of Anesthesiology, Kansai Medical University , Hirakata, Osaka , Japan
| | - Yoshifumi Sato
- Department of Medical Biochemistry, Faculty of Life Sciences, Kumamoto University , Kumamoto , Japan
| | - Shinichi Kai
- Department of Anesthesiology, Kansai Medical University , Hirakata, Osaka , Japan
| | - Kenichiro Nishi
- Department of Anesthesiology, Kansai Medical University , Hirakata, Osaka , Japan
| | - Takehiko Adachi
- Department of Anesthesia, Tazuke Kofukai Medical Research Institute Kitano Hospital , Osaka , Japan
| | - Yoshiyuki Matsuo
- Department of Anesthesiology, Kansai Medical University , Hirakata, Osaka , Japan
| | - Kiichi Hirota
- Department of Anesthesiology, Kansai Medical University , Hirakata, Osaka , Japan
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Sabatini PV, Lynn FC. All-encomPASsing regulation of β-cells: PAS domain proteins in β-cell dysfunction and diabetes. Trends Endocrinol Metab 2015; 26:49-57. [PMID: 25500169 DOI: 10.1016/j.tem.2014.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/07/2014] [Accepted: 11/11/2014] [Indexed: 12/27/2022]
Abstract
As a sensory micro-organ, pancreatic β-cells continually respond to nutritional signals and neuroendocrine input from other glucoregulatory organs. This sensory ability is essential for normal β-cell function and systemic glucose homeostasis. Period circadian protein (Per)-aryl hydrocarbon receptor nuclear translocator protein (Arnt)-single-minded protein (Sim) (PAS) domain proteins have a conserved role as sensory proteins, critical in adaptation to changes in voltage, oxygen potential, and xenobiotics. Within β-cells, PAS domain proteins such as hypoxia inducible factor 1α (Hif1α), Arnt, PAS kinase, Bmal1, and Clock respond to disparate stimuli, but act in concert to maintain proper β-cell function. Elucidating the function of these factors in islets offers a unique insight into the sensing capacity of β-cells, the consequences of impaired sensory function, and the potential to develop novel therapeutic targets for preserving β-cell function in diabetes.
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Affiliation(s)
- Paul V Sabatini
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada; The Departments of Surgery and Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, V5Z 4H4 Canada.
| | - Francis C Lynn
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada; The Departments of Surgery and Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, V5Z 4H4 Canada.
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Moderate hypoxia induces β-cell dysfunction with HIF-1-independent gene expression changes. PLoS One 2014; 9:e114868. [PMID: 25503986 PMCID: PMC4264765 DOI: 10.1371/journal.pone.0114868] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/14/2014] [Indexed: 01/09/2023] Open
Abstract
Pancreatic β-cell failure is central to the development and progression of type 2 diabetes. We recently demonstrated that β-cells become hypoxic under high glucose conditions due to increased oxygen consumption and that the pancreatic islets of diabetic mice but not those of control mice are moderately hypoxic. However, the impact of moderate hypoxia on β-cell number and function is unknown. In the present study, moderate hypoxia induced a hypoxic response in MIN6 cells, as evidenced by increased levels of HIF-1α protein and target genes. Under these conditions, a selective downregulation of Mafa, Pdx1, Slc2a2, Ndufa5, Kcnj11, Ins1, Wfs1, Foxa2, and Neurod1, which play important roles in β-cells, was also observed in both MIN6 cells and isolated pancreatic islets. Consistent with the altered expression of these genes, abnormal insulin secretion was detected in hypoxic MIN6 cells. Most of the hypoxia-induced gene downregulation in MIN6 cells was not affected by the suppression of HIF-1α, suggesting a HIF-1–independent mechanism. Moderate hypoxia also induced apoptosis in MIN6 cells. These results suggest that hypoxia is a novel stressor of β-cells and that hypoxic stress may play a role in the deterioration of β-cell function.
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35
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Soggia A, Ramond C, Akiyama H, Scharfmann R, Duvillie B. von Hippel-Lindau gene disruption in mouse pancreatic progenitors and its consequences on endocrine differentiation in vivo: importance of HIF1-α and VEGF-A upregulation. Diabetologia 2014; 57:2348-56. [PMID: 25186293 DOI: 10.1007/s00125-014-3365-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 08/11/2014] [Indexed: 12/15/2022]
Abstract
AIM/HYPOTHESIS Different studies have linked hypoxia to embryonic development. Specifically, when embryonic pancreases are cultured ex vivo under hypoxic conditions (3% O2), beta cell development is impaired. Different cellular signalling pathways are involved in adaptation to hypoxia, including the ubiquitous hypoxia-inducible-factor 1-α (HIF1-α) pathway. We aimed to analyse the effects of HIF1-α stabilisation on fetal pancreas development in vivo. METHODS We deleted the Vhl gene, which encodes von Hippel-Lindau protein (pVHL), a factor necessary for HIF1-α degradation, by crossing Vhl-floxed mice with Sox9-Cre mice. RESULTS HIF1-α was stabilised in pancreatic progenitor cells in which the HIF pathway was induced. The number of neurogenin-3 (NGN3)-expressing cells was reduced and consequently endocrine development was altered in Vhl knockout pancreases. HIF1-α stabilisation induced Vegfa upregulation, leading to increased vascularisation. To investigate the impact of increased vascularisation on NGN3 expression, we used a bioassay in which Vhl mutant pancreases were cultured with or without vascular endothelial growth factor (VEGF) receptor 2 (VEGF-R2) inhibitors (e.g. Ki8751). Ex vivo analysis showed that Vhl knockout pancreases developed fewer NGN3-positive cells compared with controls. Interestingly, this effect was blocked when vascularisation was inhibited in the presence of VEGF-R2 inhibitors. CONCLUSIONS/INTERPRETATION Our data demonstrate that HIF1-α negatively controls beta cell differentiation in vivo by regulating NGN3 expression, and that this effect is mediated by signals from blood vessels.
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Affiliation(s)
- Andrea Soggia
- U1016 Inserm/Institut Cochin, Groupe Hospitalier Cochin Port-Royal, Bâtiment Cassini, 123 Boulevard du Port-Royal, 75014, Paris, France
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García-Heredia JM, Felipe-Abrio B, Cano DA, Carnero A. Genetic modification of hypoxia signaling in animal models and its effect on cancer. Clin Transl Oncol 2014; 17:90-102. [PMID: 25351170 DOI: 10.1007/s12094-014-1236-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/24/2014] [Indexed: 12/19/2022]
Abstract
Conditions that cause hypoxemia or generalized tissue hypoxia, which can last for days, months, or even years, are very common in the human population and are among the leading causes of morbidity, disability, and mortality. Therefore, the molecular pathophysiology of hypoxia and its potential deleterious effects on human health are important issues at the forefront of biomedical research. Generalized hypoxia is a consequence of highly prevalent medical disorders that can severely reduce the capacity for O2 exchange between the air and pulmonary capillaries. In recent years, some of the key O2-dependent signaling pathways have been characterized at the molecular level. In particular, the prolyl hydroxylase (PHD)-hypoxia-inducible factor (HIF) cascade has emerged as the master regulator of a general gene expression program involved in cell/tissue/organ adaptation to hypoxia. Hypoxia has emerged as a critical factor in cancer because it can promote tumor initiation, progression, and resistance to therapy. Beyond its role in neovascularization as a mechanism of tumor adaptation to nutrient and O2 deprivation, hypoxia has been linked to prolonged cellular lifespan and immortalization, the generation of "oncometabolites", deregulation of stem cell proliferation, and inflammation, among other tumor hallmarks. Hypoxia may contribute to cancer through several independent pathways, the inter-connections of which have yet to be elucidated. Furthermore, the relevance of chronic hypoxemia in the initiation and progression of cancer has not been studied in depth in the whole organism. Therefore, we explore here the contributions of hypoxia to the whole organism by reviewing studies on genetically modified mice with alterations in the key molecular factors regulating hypoxia.
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Affiliation(s)
- J M García-Heredia
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocio/CSIC/Universidad de Sevilla, 41013, Seville, Spain
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Catrina SB. Impaired hypoxia-inducible factor (HIF) regulation by hyperglycemia. J Mol Med (Berl) 2014; 92:1025-34. [PMID: 25027070 DOI: 10.1007/s00109-014-1166-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 05/06/2014] [Accepted: 05/08/2014] [Indexed: 12/13/2022]
Abstract
The mechanisms that contribute to the development of diabetes complications remain unclear. A defective reaction of tissues to hypoxia has recently emerged as a new pathogenic mechanism and consists of a complex repression of hypoxia-inducible factor (HIF), which is the main regulator of the adaptive response to hypoxia. This paper discusses the mechanisms by which hyperglycaemia contributes to HIF repression in diabetes. Furthermore, a comprehensive analysis of the functional relevance of these new findings to the development of chronic diabetes complications is provided, along with examples from animal models and clinics.
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Affiliation(s)
- Sergiu-Bogdan Catrina
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital, L1:01, 17176, Stockholm, Sweden,
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Matsunaga T, Li S, Adachi T, Joo E, Gu N, Yamazaki H, Yasuda K, Kondoh T, Tsuda K. Hyperoxia reverses glucotoxicity-induced inhibition of insulin secretion in rat INS-1 β cells. Biosci Biotechnol Biochem 2014; 78:843-50. [PMID: 25035988 DOI: 10.1080/09168451.2014.905175] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chronic hyperglycemia has deleterious effects on pancreatic β-cell function, a process known as glucotoxicity. This study examined whether chronic high glucose (CHG) induces cellular hypoxia in rat INS-1 β cells, and whether hyperoxia (35% O2) can reverse glucotoxicity-induced inhibition of insulin secretion. CHG (33.3 mm, 96 h) reduced insulin secretion, and down-regulated insulin and pancreatic duodenal homeobox factor 1 gene expression. CHG also increased intracellular pimonidazole-protein adducts, a marker for hypoxia. CHG also enhanced hypoxia-inducible factor 1α (HIF-1α) protein expression and its DNA-binding activity, which was accompanied by a decrease in mRNA expression of glucose transporter 2 (GLUT2), glucokinase and uncoupling protein-2 and an increase in mRNA expression of GLUT1 and pyruvate dehydrogenase kinase 1. Hyperoxia restored the decrease in insulin secretion and the gene expression except for GLUT2, and suppressed intracellular hypoxia and HIF-1α activation. These results suggest that glucotoxicity may cause β-cell hypoxia. Hyperoxia might prevent glucotoxicity-induced β-cell dysfunction and improve insulin secretion.
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Affiliation(s)
- Tetsuro Matsunaga
- a Faculty of Health and Living Sciences Education , Naruto University of Education , Naruto , Japan
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Atchison N, Swindlehurst G, Papas KK, Tsapatsis M, Kokkoli E. Maintenance of ischemic β cell viability through delivery of lipids and ATP by targeted liposomes. Biomater Sci 2014; 2:548-559. [PMID: 24653833 PMCID: PMC3955996 DOI: 10.1039/c3bm60094g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Islet transplantation is a promising treatment for type 1 diabetes, but despite the successes, existing challenges prevent widespread application. Ischemia, occurring during pancreas preservation and isolation, as well as after islet transplantation, decreases islet viability and function. We hypothesized that the liposomal delivery of adenosine triphosphate (ATP) could prevent the loss of cell viability during an ischemic insult. In this work we use a model β cell line, INS-1 to probe the liposome/cell interactions and examined the ability of liposomes functionalized with the fibronectin-mimetic peptide PR_b to facilitate the delivery of ATP to ischemic β cells. We demonstrate that PR_b increases the binding and internalization of liposomes to the β cells. Unexpectedly, when comparing the ability of PR_b liposomes with and without ATP to protect INS-1 cells from ischemia we found that both formulations increased cell survival. By probing the functional activity of ischemic cells treated with PR_b functionalized liposomes with and without ATP we find that both lipids and ATP play a role in maintaining cell metabolic activity after an ischemic insult and preventing cell necrosis. This approach may be beneficial for preventing ischemia related damage to islet cells, especially in the organ preservation stage.
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Affiliation(s)
- Nicole Atchison
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Garrett Swindlehurst
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA. Fax: 612- 626-7246; Tel: 612-626-1185
| | | | - Michael Tsapatsis
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA. Fax: 612- 626-7246; Tel: 612-626-1185
| | - Efrosini Kokkoli
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA. Fax: 612- 626-7246; Tel: 612-626-1185
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Alismail H, Jin S. Microenvironmental stimuli for proliferation of functional islet β-cells. Cell Biosci 2014; 4:12. [PMID: 24594290 PMCID: PMC3974598 DOI: 10.1186/2045-3701-4-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 01/29/2014] [Indexed: 12/31/2022] Open
Abstract
Diabetes is characterized by high blood glucose level due to either autoimmune destruction of islet β-cells or insufficient insulin secretion or glucose non-responsive production of insulin by β-cells. It is highly desired to replace biological functional β-cells for the treatment of diabetes. Unfortunately, β-cells proliferate with an extremely low rate. This cellular property hinders cell-based therapy for clinical application. Many attempts have been made to develop techniques that allow production of large quantities of clinically relevant islet β-cells in vitro. A line of studies evidently demonstrate that β-cells can proliferate under certain circumstances, giving the hopes for generating and expanding these cells in vitro and transplanting them to the recipient. In this review, we discuss the requirements of microenvironmental stimuli that stimulate β-cell proliferation in cell cultures. We highlight advanced approaches for augmentation of β-cell expansion that have recently emerged in this field. Furthermore, knowing the signaling pathways and molecular mechanisms would enable manipulating cell proliferation and optimizing its insulin secretory function. Thus, signaling pathways involved in the enhancement of cell proliferation are discussed as well.
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Affiliation(s)
| | - Sha Jin
- Department of Bioengineering, Thomas J, Watson School of Engineering and Applied Sciences, State University of New York in Binghamton, Binghamton, NY 13902, USA.
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Puri S, Akiyama H, Hebrok M. VHL-mediated disruption of Sox9 activity compromises β-cell identity and results in diabetes mellitus. Genes Dev 2014; 27:2563-75. [PMID: 24298056 PMCID: PMC3861670 DOI: 10.1101/gad.227785.113] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
β-Cell dysfunction contributes to diabetes mellitus. Puri et al. show that deletion of the von Hippel-Lindau (Vhlh) gene is deleterious to canonical β-cell gene expression. Vhlh loss triggers erroneous expression of factors normally active in progenitor cells, including Sox9. β-Cell-specific expression of Sox9 results in diabetes mellitus. This study reveals that perturbed β-cell identity contributes to diabetes mellitus. Precise functioning of the pancreatic β cell is paramount to whole-body glucose homeostasis, and β-cell dysfunction contributes significantly to diabetes mellitus. Using transgenic mouse models, we demonstrate that deletion of the von Hippel-Lindau (Vhlh) gene (encoding an E3 ubiquitin ligase implicated in, among other functions, oxygen sensing in pancreatic β cells) is deleterious to canonical β-cell gene expression. This triggers erroneous expression of factors normally active in progenitor cells, including effectors of the Notch, Wnt, and Hedgehog signaling cascades. Significantly, an up-regulation of the transcription factor Sox9, normally excluded from functional β cells, occurs upon deletion of Vhlh. Sox9 plays important roles during pancreas development but does not have a described role in the adult β cell. β-Cell-specific ectopic expression of Sox9 results in diabetes mellitus from similar perturbations in β-cell identity. These findings reveal that assaults on the β cell that impact the differentiation state of the cell have clear implications toward our understanding of diabetes mellitus.
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Affiliation(s)
- Sapna Puri
- Diabetes Center, Department of Medicine, University of California at San Francisco, San Francisco, California 94143, USA
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Brunt JJ, Shi SY, Schroer SA, Sivasubramaniyam T, Cai EP, Woo M. Overexpression of HIF-2α in pancreatic β cells does not alter glucose homeostasis. Islets 2014; 6:e1006075. [PMID: 25833250 PMCID: PMC4398283 DOI: 10.1080/19382014.2015.1006075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Both type 1 and type 2 diabetes are associated with insufficient functional β-cell mass. Understanding intracellular signaling pathways associated with this decline is important in broadening our understanding of the disease and potential therapeutic strategies. The hypoxia inducible factor pathway (HIF) plays a critical role in cellular adaptation to hypoxic conditions. Activation of this pathway increases expression of numerous genes involved in multiple cellular processes and has been shown to impact the regulation of β-cell function. Previously, deletion of HIF-1α or HIF-1β in pancreatic β-cells, as well as constitutive activation of the HIF pathway in β-cells, was shown to result in glucose intolerance and impaired insulin secretion. The objective of this study was to delineate roles of HIF-2α overexpression in pancreatic β-cells in vivo. We overexpressed HIF-2α in pancreatic β-cells by employing the Cre-loxP system driven by the Pdx1 promoter to delete a stop codon. Our study revealed that pancreatic HIF-2α overexpression does not result in significant differences in glucose tolerance, insulin sensitivity or β-cell area compared to wild-type littermates under basal conditions or after high fat diet. Together, our study shows excess HIF-2α in the pancreatic β-cells does not play a significant role in β-cell function and glucose homeostasis.
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Key Words
- ARNT, aryl hydrocarbon receptor nuclear translocator
- EPAS1, endothelial PAS domain protein 1
- GLUT1 glucose transporter 1
- GTT, glucose tolerance test
- HFD, high fat diet
- HIF, hypoxia inducible factor
- HIF-1α, hypoxia inducible factor-1 α
- HIF-1β, hypoxia inducible factor-1 β
- HIF-2α, hypoxia inducible factor-2 α
- Hypoxia inducible factor β cell glucose homeostasis diabetes mellitus pancreas
- ITT, insulin tolerance test
- OE, overexpression
- VEGF, vascular endothelial growth factor
- VHL, von Hippel-Lindau
- WT, wild-type
- i.p., intraperitoneal
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Affiliation(s)
- Jara J Brunt
- Toronto General Research
Institute; Toronto, Canada
- Institute of Medical Science; University of
Toronto; Toronto, Canada
| | - Sally Yu Shi
- Toronto General Research
Institute; Toronto, Canada
- Institute of Medical Science; University of
Toronto; Toronto, Canada
| | | | - Tharini Sivasubramaniyam
- Toronto General Research
Institute; Toronto, Canada
- Institute of Medical Science; University of
Toronto; Toronto, Canada
| | - Erica P Cai
- Toronto General Research
Institute; Toronto, Canada
- Institute of Medical Science; University of
Toronto; Toronto, Canada
| | - Minna Woo
- Toronto General Research
Institute; Toronto, Canada
- Institute of Medical Science; University of
Toronto; Toronto, Canada
- Division of Endocrinology; Department of
Medicine; Toronto General Hospital; University Health Network; University of
Toronto; Toronto, Canada
- Correspondence to: Minna Woo;
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Ku YH, Ahn CH, Jung CH, Lee JE, Kim LK, Kwak SH, Jung HS, Park KS, Cho YM. A novel mutation in the von hippel-lindau tumor suppressor gene identified in a patient presenting with gestational diabetes mellitus. Endocrinol Metab (Seoul) 2013; 28:320-5. [PMID: 24396697 PMCID: PMC3871045 DOI: 10.3803/enm.2013.28.4.320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 09/03/2013] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Von Hippel-Lindau (VHL) disease is an autosomal dominantly inherited, multisystemic tumor syndrome caused by mutations in the VHL gene. To date, more than 1,000 germline and somatic mutations of the VHL gene have been reported. We present a novel mutation in the VHL tumor suppressor gene that presented with gestational diabetes mellitus. METHODS A 30-year-old woman presented with gestational diabetes mellitus. She sequentially showed multiple pancreatic cysts, spinal cord hemangioblastoma, cerebellar hemangioblastoma, and clear cell type renal cell carcinomas. Also, her father and brother had brain hemangioblastomas. Each of the three exons of the VHL gene was individually amplified by polymerase chain reaction and direct sequencing was performed using an ABI 3730 DNA analyzer. RESULTS DNA sequence analysis to determine the presence of VHL mutation in her family revealed del291C, a novel frameshift mutation. CONCLUSION We found a novel mutation in the VHL tumor suppressor gene that presented with gestational diabetes mellitus.
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Affiliation(s)
- Yun Hyi Ku
- Department of Internal Medicine, Korea Cancer Center Hospital, Seoul, Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Chang Ho Ahn
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Chan-Hyeon Jung
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jie Eun Lee
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Lee-Kyung Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Soo Heon Kwak
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Hye Seung Jung
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Kyong Soo Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Young Min Cho
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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45
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Hypoxia as a target for tissue specific gene therapy. J Control Release 2013; 172:484-94. [DOI: 10.1016/j.jconrel.2013.05.021] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 05/13/2013] [Accepted: 05/24/2013] [Indexed: 12/28/2022]
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Cantley J, Walters SN, Jung MH, Weinberg A, Cowley MJ, Whitworth PT, Kaplan W, Hawthorne WJ, O'connell PJ, Weir G, Grey ST. A Preexistent Hypoxic Gene Signature Predicts Impaired Islet Graft Function and Glucose Homeostasis. Cell Transplant 2013; 22:2147-59. [DOI: 10.3727/096368912x658728] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We examined whether hypoxic exposure prior to the event of transplantation would have a positive or negative effect upon later islet graft function. Mouse islets exposed to hypoxic culture were transplanted into syngeneic recipients. Islet graft function, β-cell physiology, as well as molecular changes were examined. Expression of hypoxia-response genes in human islets pre- and posttransplant was examined by microarray. Hypoxia-preexposed murine islet grafts provided poor glycemic control in their syngeneic recipients, marked by persistent hyperglycemia and pronounced glucose intolerance with failed first- and second-phase glucose-stimulated insulin secretion in vivo. Mechanistically, hypoxic preexposure stabilized HIF-1α with a concomitant increase in hypoxic-response genes including LDHA, and a molecular gene set, which would favor glycolysis and lactate production and impair glucose sensing. Indeed, static incubation studies showed that hypoxia-exposed islets exhibited dysregulated glucose responsiveness with elevated basal insulin secretion. Isolated human islets, prior to transplantation, express a characteristic hypoxia-response gene expression signature, including high levels of LDHA, which is maintained posttransplant. Hypoxic preexposure of an islet graft drives a HIF-dependent switch to glycolysis with subsequent poor glycemic control and loss of glucose-stimulated insulin secretion (GSIS). Early intervention to reverse or prevent these hypoxia-induced metabolic gene changes may improve clinical islet transplantation.
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Affiliation(s)
- James Cantley
- Diabetes and Obesity Research Program, Garvan Institute, Darlinghurst, New South Wales, Australia
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Stacey N. Walters
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
- Immunology Program, Garvan Institute, Darlinghurst, New South Wales, Australia
| | - Min-Ho Jung
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, USA
| | - Anita Weinberg
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
- Immunology Program, Garvan Institute, Darlinghurst, New South Wales, Australia
| | - Mark J. Cowley
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
- Cancer Program, Garvan Institute, Darlinghurst, New South Wales, Australia
| | - P. Tess Whitworth
- Diabetes and Obesity Research Program, Garvan Institute, Darlinghurst, New South Wales, Australia
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Warren Kaplan
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
- Peter Wills Bioinformatics Centre, Garvan Institute, Darlinghurst, New South Wales, Australia
| | - Wayne J. Hawthorne
- The Centre for Transplant and Renal Research, Westmead Hospital, Westmead, New South Wales, Australia
| | - Philip J. O'connell
- The Centre for Transplant and Renal Research, Westmead Hospital, Westmead, New South Wales, Australia
| | - Gordon Weir
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, USA
| | - Shane T. Grey
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, New South Wales, Australia
- Immunology Program, Garvan Institute, Darlinghurst, New South Wales, Australia
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Elimination of von Hippel-Lindau function perturbs pancreas endocrine homeostasis in mice. PLoS One 2013; 8:e72213. [PMID: 23977255 PMCID: PMC3748057 DOI: 10.1371/journal.pone.0072213] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 07/08/2013] [Indexed: 12/23/2022] Open
Abstract
Mutations in the human homolog of the Vhlh gene [encoding the von-Hippel Lindau (VHL) protein] lead to tumor development. In mice, depletion of Vhlh in pancreatic ß-cells causes perturbed glucose homeostasis, but the role of this gene in other pancreatic cells is poorly understood. To investigate the function of VHL/HIF pathway in pancreatic cells, we inactivated Vhlh in the pancreatic epithelium as well as in the endocrine and exocrine lineages. Our results show that embryonic depletion of Vhlh within the pancreatic epithelium causes postnatal lethality due to severe hypoglycemia. The hypoglycemia is recapitulated in mice with endocrine-specific removal of Vhlh, while animals with loss of Vhlh predominantly in the exocrine compartment survive to adulthood with no overt defects in glucose metabolism. Mice with hypoglycemia display diminished insulin release in response to elevated glucose. Significantly, the glucagon response is impaired both in vivo (circulating glucagon levels) as well as in an in vitro secretion assay in isolated islets. Hypoxia also impairs glucagon secretion in a glucagon-expressing cell line in culture. Our results reveal a novel role for the hypoxia/HIF pathway in islet hormone secretion and maintenance of the fine balance that allows for the establishment of normoglycemia.
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Muñoz-Bravo JL, Hidalgo-Figueroa M, Pascual A, López-Barneo J, Leal-Cerro A, Cano DA. GDNF is required for neural colonization of the pancreas. Development 2013; 140:3669-79. [PMID: 23903190 DOI: 10.1242/dev.091256] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mammalian pancreas is densely innervated by both the sympathetic and parasympathetic nervous systems, which control exocrine and endocrine secretion. During embryonic development, neural crest cells migrating in a rostrocaudal direction populate the gut, giving rise to neural progenitor cells. Recent studies in mice have shown that neural crest cells enter the pancreatic epithelium at E11.5. However, the cues that guide the migration of neural progenitors into the pancreas are poorly defined. In this study we identify glial cell line-derived neurotrophic factor (GDNF) as a key player in this process. GDNF displays a dynamic expression pattern during embryonic development that parallels the chronology of migration and differentiation of neural crest derivatives in the pancreas. Conditional inactivation of Gdnf in the pancreatic epithelium results in a dramatic loss of neuronal and glial cells and in reduced parasympathetic innervation in the pancreas. Importantly, the innervation of other regions of the gut remains unaffected. Analysis of Gdnf mutant mouse embryos and ex vivo experiments indicate that GDNF produced in the pancreas acts as a neurotrophic factor for gut-resident neural progenitor cells. Our data further show that exogenous GDNF promotes the proliferation of pancreatic progenitor cells in organ culture. In summary, our results point to GDNF as crucial for the development of the intrinsic innervation of the pancreas.
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Affiliation(s)
- José Luis Muñoz-Bravo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Sevilla, Seville, Spain
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49
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Kurabayashi A, Kakinuma Y, Morita T, Inoue K, Sato T, Furihata M. Conditional VHL gene deletion causes hypoglycemic death associated with disproportionately increased glucose uptake by hepatocytes through an upregulated IGF-I receptor. PLoS One 2013; 8:e69139. [PMID: 23874892 PMCID: PMC3706433 DOI: 10.1371/journal.pone.0069139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/04/2013] [Indexed: 01/08/2023] Open
Abstract
Our conditional VHL knockout (VHL-KO) mice, having VHL gene deletion induced by tamoxifen, developed severe hypoglycemia associated with disproportionately increased storage of PAS-positive substances in the liver and resulted in the death of these mice. This hypoglycemic state was neither due to impaired insulin secretion nor insulin receptor hypersensitivity. By focusing on insulin-like growth factor I (IGF-I), which has a similar effect on glucose metabolism as the insulin receptor, we demonstrated that IGF-I receptor (IGF-IR) protein expression in the liver was upregulated in VHL-KO mice compared to that in the mice without VHL deletion, as was the expression of glucose transporter (GLUT) 1. The interaction of the receptor for activated C kinase (RACK) 1, which predominantly binds to VHL, was enhanced in VHL-KO livers with IGF-IR, because VHL deletion increased free RACK1 and facilitated the IGF-IR-RACKI interaction. An IGF-IR antagonist retarded hypoglycemic progression and sustained an euglycemic state. These IGF-IR antagonist effects on restoring blood glucose levels also attenuated PAS-positive substance storage in the liver. Because the effect of IGF-I on HIF-1α protein synthesis is mediated by IGF-IR, our results indicated that VHL inactivation accelerated hepatic glucose storage through the upregulation of IGF-IR and GLUT1 and that IGF-IR was a key regulator in VHL-deficient hepatocytes.
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Affiliation(s)
| | - Yoshihiko Kakinuma
- Department of Cardiovascular Control, Kochi Medical School, Nankoku, Kochi, Japan
- * E-mail:
| | - Taku Morita
- Department of Pediatrics, Ashiya Municipal Hospital, Ashiya, Hyogo, Japan
| | - Keiji Inoue
- Department of Urology, Kochi Medical School, Nankoku, Kochi, Japan
| | - Takayuki Sato
- Department of Cardiovascular Control, Kochi Medical School, Nankoku, Kochi, Japan
| | - Mutsuo Furihata
- Department of Pathology, Kochi Medical School, Nankoku, Kochi, Japan
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50
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Pullen TJ, Rutter GA. When less is more: the forbidden fruits of gene repression in the adult β-cell. Diabetes Obes Metab 2013; 15:503-12. [PMID: 23121289 DOI: 10.1111/dom.12029] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 10/08/2012] [Accepted: 10/28/2012] [Indexed: 12/15/2022]
Abstract
Outside of the biological arena the term 'repression' often has a negative connotation. However, in the pancreatic β-cell a small group of genes, which are abundantly expressed in most if not all other mammalian tissues, are highly selectively repressed, with likely functional consequences. The two 'founder' members of this group, lactate dehydrogenase A (Ldha) and monocarboxylate transporter-1 (MCT-1/Slc16a1), are inactivated by multiple mechanisms including histone modifications and microRNA-mediated silencing. Their inactivation ensures that pyruvate and lactate, derived from muscle during exercise, do not stimulate insulin release inappropriately. Correspondingly, activating mutations in the MCT-1 promoter underlie 'exercise-induced hyperinsulinism' (EIHI) in man, a condition mimicked by forced over-expression of MCT-1 in the β-cell in mice. Furthermore, LDHA expression in the β-cell is upregulated in both human type 2 diabetes and in rodent models of the disease. Recent work by us and by others has identified a further ∼60 genes which are selectively inactivated in the β-cell, a list which we refine here up to seven by detailed comparison of the two studies. These genes include key regulators of cell proliferation and stimulus-secretion coupling. The present, and our earlier results, thus highlight the probable importance of shutting down a subset of 'disallowed' genes for the differentiated function of β-cells, and implicate previously unsuspected signalling pathways in the control of β-cell expansion and insulin secretion. Targeting of deregulated 'disallowed' genes in these cells may thus, in the future, provide new therapeutic avenues for type 2 diabetes.
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Affiliation(s)
- T J Pullen
- Section of Cell Biology, Department of Medicine, Imperial College London, London, UK
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