1
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Chi Y, Zhang X, Liang D, Wang Y, Cai X, Dong J, Li L, Chi Z. ZnT8 Exerts Anti-apoptosis of Kidney Tubular Epithelial Cell in Diabetic Kidney Disease Through TNFAIP3-NF-κB Signal Pathways. Biol Trace Elem Res 2023; 201:2442-2457. [PMID: 35871203 DOI: 10.1007/s12011-022-03361-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 07/13/2022] [Indexed: 02/05/2023]
Abstract
Apoptosis of kidney tubular epithelial cells contributes to diabetic kidney disease (DKD) pathophysiology, but the mechanisms are not fully understood. Zinc transporter protein member 8 (ZnT8, SLC30A8) is a susceptive gene in diabetes. Here, we aim to investigate whether ZnT8 has effects on pathophysiology of DKD. The animal groups include control, ZnT8KO mice, STZ-induced, and ZnT8-KO-STZ. STZ-induced DKD was performed in male C57BL/6 J mice and in ZnT8-KO mice. High glucose (HG)-induced apoptosis in a normal rat kidney tubular epithelial cell line (NRK-52E cells) was performed in vitro. Transfection of hZnT8-EGFP or TNFAIP3 siRNA was done in NRK-52E cells. Flow cytometry with Annexin V-FITC/PI double staining and TUNEL analysis was performed for the detection of apoptosis. Gene expression at mRNA and protein levels was examined with real-time RT-PCR and Western blot. Urine albumin to creatinine ratio, proinflammatory cytokines, and apoptosis were enhanced in kidneys of STZ and ZnT8-KO-STZ mice compared to control or ZnT8-KO mice. ZnT8 overexpression after hZnT8-EGFP transfection decreased HG-stimulated inflammatory activity and apoptosis in NRK-52E cells. Furthermore, treatment with ZnSO4 blunted HG-induced apoptosis and NF-κB activation. ZnSO4 increased the abundance of zinc-finger protein TNF-α-induced protein 3 (TNFAIP3). Also, ZnT8 over-expression after hZnT8-EGFP transfection significantly ameliorates HG-induced NF-κB-dependent transcriptional activity and apoptotic protein expressions in NRK-52E cells, but the inhibitory effect of ZnT8 was significantly abolished with TNFAIP3 siRNA. Our study provides evidence that ZnT8 has protective effects against apoptosis of renal tubular epithelial cells through induction of TNFAIP3 and subsequent suppression of the NF-κB pathway.
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Affiliation(s)
- Yinmao Chi
- Department of Physiology, China Medical University, Shenyang, Liaoning Province, 110001, People's Republic of China
| | - Xiuli Zhang
- Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, Guangdong Province, 518000, People's Republic of China.
- Department of Nephrology, Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong Province, 518000, People's Republic of China.
| | - Dan Liang
- Troops of 95988 Unit, Changchun, Jilin, 158000, People's Republic of China
| | - Yue Wang
- Department of Tissue Culture, Liaoning University of Traditional Chinese Medicine, Shenyang, Liaoning Province, 110001, People's Republic of China
| | - Xiaoyi Cai
- Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, Guangdong Province, 518000, People's Republic of China
- Shantou University Medical College, Shantou, Guangdong Province, 515000, People's Republic of China
| | - Jiqiu Dong
- Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, Guangdong Province, 518000, People's Republic of China
| | - Lingzhi Li
- Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, Guangdong Province, 518000, People's Republic of China
| | - Zhihong Chi
- Department of Pathophysiology, China Medical University, Shenyang, Liaoning Province, 110001, People's Republic of China
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2
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Gao D, Jiao J, Wang Z, Huang X, Ni X, Fang S, Zhou Q, Zhu X, Sun L, Yang Z, Yuan H. The roles of cell-cell and organ-organ crosstalk in the type 2 diabetes mellitus associated inflammatory microenvironment. Cytokine Growth Factor Rev 2022; 66:15-25. [PMID: 35459618 DOI: 10.1016/j.cytogfr.2022.04.002] [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: 02/22/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a classic metaflammatory disease, and the inflammatory states of the pancreatic islet and insulin target organs have been well confirmed. However, abundant evidence demonstrates that there are countless connections between these organs in the presence of a low degree of inflammation. In this review, we focus on cell-cell crosstalk among local cells in the islet and organ-organ crosstalk among insulin-related organs. In contrast to that in acute inflammation, macrophages are the dominant immune cells causing inflammation in the islets and insulin target organs in T2DM. In the inflammatory microenvironment (IME) of the islet, cell-cell crosstalk involving local macrophage polarization and proinflammatory cytokine production impair insulin secretion by β-cells. Furthermore, organ-organ crosstalk, including the gut-brain-pancreas axis and interactions among insulin-related organs during inflammation, reduces insulin sensitivity and induces endocrine dysfunction. Therefore, this crosstalk ultimately results in a cascade leading to β-cell dysfunction. These findings could have broad implications for therapies aimed at treating T2DM.
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Affiliation(s)
- Danni Gao
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China; Peking University Fifth School of Clinical Medicine, Beijing 100730, PR China
| | - Juan Jiao
- Department of Clinical Laboratory, the Seventh Medical Centre of Chinese PLA General Hospital, Beijing 100700, PR China
| | - Zhaoping Wang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Xiuqing Huang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Xiaolin Ni
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Sihang Fang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Qi Zhou
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Xiaoquan Zhu
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Liang Sun
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Ze Yang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China
| | - Huiping Yuan
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology of National Health Commission, Beijing 100730, PR China; Peking University Fifth School of Clinical Medicine, Beijing 100730, PR China.
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3
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Karsai M, Zuellig RA, Lehmann R, Cuozzo F, Nasteska D, Luca E, Hantel C, Hodson DJ, Spinas GA, Rutter GA, Gerber PA. Lack of ZnT8 protects pancreatic islets from hypoxia- and cytokine-induced cell death. J Endocrinol 2022; 253:1-11. [PMID: 35017316 PMCID: PMC8859919 DOI: 10.1530/joe-21-0271] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/11/2022] [Indexed: 11/10/2022]
Abstract
Pancreatic β-cells depend on the well-balanced regulation of cytosolic zinc concentrations, providing sufficient zinc ions for the processing and storage of insulin, but avoiding toxic effects. The zinc transporter ZnT8, encoded by SLC30A8,is a key player regarding islet cell zinc homeostasis, and polymorphisms in this gene are associated with altered type 2 diabetes susceptibility in man. The objective of this study was to investigate the role of ZnT8 and zinc in situations of cellular stress as hypoxia or inflammation. Isolated islets of WT and global ZnT8-/- mice were exposed to hypoxia or cytokines and cell death was measured. To explore the role of changing intracellular Zn2+ concentrations, WT islets were exposed to different zinc concentrations using zinc chloride or the zinc chelator N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN). Hypoxia or cytokine (TNF-α, IFN-γ, IL1-β) treatment induced islet cell death, but to a lesser extent in islets from ZnT8-/- mice, which were shown to have a reduced zinc content. Similarly, chelation of zinc with TPEN reduced cell death in WT islets treated with hypoxia or cytokines, whereas increased zinc concentrations aggravated the effects of these stressors. This study demonstrates a reduced rate of cell death in islets from ZnT8-/- mice as compared to WT islets when exposed to two distinct cellular stressors, hypoxia or cytotoxic cytokines. This protection from cell death is, in part, mediated by a reduced zinc content in islet cells of ZnT8-/- mice. These findings may be relevant for altered diabetes burden in carriers of risk SLC30A8 alleles in man.
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Affiliation(s)
- Maria Karsai
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Richard A Zuellig
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Roger Lehmann
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Federica Cuozzo
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Daniela Nasteska
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Edlira Luca
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Constanze Hantel
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
- Medizinische Klinik und Poliklinik III, University Hospital Carl Gustav Carus Dresden, Dresden, Germany
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Giatgen A Spinas
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
- CR-CHUM, University of Montreal, Montreal, QC, Canada
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Philipp A Gerber
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland
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4
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Toren E, Burnette KS, Banerjee RR, Hunter CS, Tse HM. Partners in Crime: Beta-Cells and Autoimmune Responses Complicit in Type 1 Diabetes Pathogenesis. Front Immunol 2021; 12:756548. [PMID: 34691077 PMCID: PMC8529969 DOI: 10.3389/fimmu.2021.756548] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 09/13/2021] [Indexed: 12/11/2022] Open
Abstract
Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated destruction of insulin-producing pancreatic beta-cells. Loss of beta-cells leads to insulin insufficiency and hyperglycemia, with patients eventually requiring lifelong insulin therapy to maintain normal glycemic control. Since T1D has been historically defined as a disease of immune system dysregulation, there has been little focus on the state and response of beta-cells and how they may also contribute to their own demise. Major hurdles to identifying a cure for T1D include a limited understanding of disease etiology and how functional and transcriptional beta-cell heterogeneity may be involved in disease progression. Recent studies indicate that the beta-cell response is not simply a passive aspect of T1D pathogenesis, but rather an interplay between the beta-cell and the immune system actively contributing to disease. Here, we comprehensively review the current literature describing beta-cell vulnerability, heterogeneity, and contributions to pathophysiology of T1D, how these responses are influenced by autoimmunity, and describe pathways that can potentially be exploited to delay T1D.
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Affiliation(s)
- Eliana Toren
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, AL, United States
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - KaLia S. Burnette
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ronadip R. Banerjee
- Division of Endocrinology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Chad S. Hunter
- Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, AL, United States
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Hubert M. Tse
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
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5
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Slepchenko KG, Chen S, Counts GP, Corbin KL, Colvin RA, Nunemaker CS. Synchrotron fluorescence imaging of individual mouse beta-cells reveals changes in zinc, calcium, and iron in a model of low-grade inflammation. Metallomics 2021; 13:6353533. [PMID: 34402906 DOI: 10.1093/mtomcs/mfab051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/02/2021] [Indexed: 12/31/2022]
Abstract
Pancreatic beta-cells synthesize and secrete insulin maintaining an organism's energy homeostasis. In humans, beta-cell dysfunction and death contribute to the pathogenesis of type 2 diabetes (T2D). Although the causes of beta-cell dysfunction are complex, obesity-induced low-grade systemic inflammation plays a role. For example, obese individuals exhibiting increased levels of proinflammatory cytokines IL-6 and IL-1beta have a higher risk of beta-cell dysfunction and T2D. Interestingly, obesity-induced inflammation changes the expression of several cellular metal regulating genes, prompting this study to examine changes in the beta-cell metallome after exposure to proinflammatory-cytokines. Primary mouse beta-cells were exposed to a combination of IL-6 and IL-1beta for 48 hours, were chemically fixed and imaged by synchrotron X-ray fluorescent microscopy. Quantitative analysis showed a surprising 2.4-fold decrease in the mean total cellular content of zinc from 158 ± 57.7 femtograms (fg) to 65.7 ± 29.7 fg; calcium decreased from 216 ± 67.4 to 154.3 ± 68.7 fg (control vs. cytokines, respectively). The mean total cellular iron content slightly increased from 30.4 ± 12.2 to 47.2 ± 36.4 fg after cytokine treatment; a sub-population of cells (38%) exhibited larger increases of iron density. Changes in the subcellular distributions of zinc and calcium were observed after cytokine exposure. Beta-cells contained numerous iron puncta that accumulated still more iron after exposure to cytokines. These findings provide evidence that exposure to low levels of cytokines is sufficient to cause changes in the total cellular content and/or subcellular distribution of several metals known to be critical for normal beta-cell function.
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Affiliation(s)
- Kira G Slepchenko
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA.,Molecular and Cellular Biology, Ohio University, Athens, Ohio, USA.,Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - Si Chen
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois, USA
| | - Grace P Counts
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - Kathryn L Corbin
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - Robert A Colvin
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA.,Molecular and Cellular Biology, Ohio University, Athens, Ohio, USA
| | - Craig S Nunemaker
- Molecular and Cellular Biology, Ohio University, Athens, Ohio, USA.,Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
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6
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Wang J, Wong WP, Link EO, Olivares S, Adelman CT, Henkel AS, El Muayed M. Single well, single-common primer pair, dual probe, duplex qPCR assay for the quantification of mRNA splicing variants. Biol Methods Protoc 2021; 6:bpab002. [PMID: 33655078 PMCID: PMC7903517 DOI: 10.1093/biomethods/bpab002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/31/2021] [Accepted: 02/05/2021] [Indexed: 12/03/2022] Open
Abstract
Quantifying the ratio of alternatively spliced mRNA variants of genes with known alternative splicing variants is highly relevant for many applications. Herein, we describe the validation of a quantitative PCR design for the simplified quantification of known mRNA splice variants. The assay uses a single-common primer pair, dual probe design for the determination of splicing variants in a single well configuration. We used murine XBP-1 splicing variants, XBP-1S and XBP-1U, to validate and demonstrate the performance characteristics of this approach. Using synthetic XBP-1S and XBP-1U cDNA as well as cDNA synthesized from mouse beta-cell line MIN6, we established the performance parameters and dynamic range of the assay. Reliable quantification of both variants at varying concentration gradients was shown. No cross detection of XBP-1U by the XBP-1S probe was detected and only marginal XBP-1S cross detection by the XBP-1U probe was detected at high concentration gradients that are unlikely to be relevant. We demonstrated that the assay accurately detected changes of XBP-1 splice variants in mouse liver subjected to pharmacologically induced ER stress without the need for normalization to a reference gene.
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Affiliation(s)
- Janice Wang
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Winifred P Wong
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Emma O Link
- Masters of Biomedical Studies Program, Drexel University, Philadelphia, PA 19104, USA
| | - Shantel Olivares
- Division of Gastroenterology and Hepatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Cade T Adelman
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.,Department of Biomedical Engineering, George Washington University School of Engineering and Applied Sciences, Washington, DC 20052, USA
| | - Anne S Henkel
- Division of Gastroenterology and Hepatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Malek El Muayed
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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7
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The role of labile Zn 2+ and Zn 2+-transporters in the pathophysiology of mitochondria dysfunction in cardiomyocytes. Mol Cell Biochem 2020; 476:971-989. [PMID: 33225416 DOI: 10.1007/s11010-020-03964-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/23/2020] [Indexed: 02/06/2023]
Abstract
An important energy supplier of cardiomyocytes is mitochondria, similar to other mammalian cells. Studies have demonstrated that any defect in the normal processes controlled by mitochondria can lead to abnormal ROS production, thereby high oxidative stress as well as lack of ATP. Taken into consideration, the relationship between mitochondrial dysfunction and overproduction of ROS as well as the relation between increased ROS and high-level release of intracellular labile Zn2+, those bring into consideration the importance of the events related with those stimuli in cardiomyocytes responsible from cellular Zn2+-homeostasis and responsible Zn2+-transporters associated with the Zn2+-homeostasis and Zn2+-signaling. Zn2+-signaling, controlled by cellular Zn2+-homeostatic mechanisms, is regulated with intracellular labile Zn2+ levels, which are controlled, especially, with the two Zn2+-transporter families; ZIPs and ZnTs. Our experimental studies in mammalian cardiomyocytes and human heart tissue showed that Zn2+-transporters localizes to mitochondria besides sarco(endo)plasmic reticulum and Golgi under physiological condition. The protein levels as well as functions of those transporters can re-distribute under pathological conditions, therefore, they can interplay among organelles in cardiomyocytes to adjust a proper intracellular labile Zn2+ level. In the present review, we aimed to summarize the already known Zn2+-transporters localize to mitochondria and function to stabilize not only the cellular Zn2+ level but also cellular oxidative stress status. In conclusion, one can propose that a detailed understanding of cellular Zn2+-homeostasis and Zn2+-signaling through mitochondria may emphasize the importance of new mitochondria-targeting agents for prevention and/or therapy of cardiovascular dysfunction in humans.
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8
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Wang TY, Liu XJ, Xie JY, Yuan QZ, Wang Y. Cask methylation involved in the injury of insulin secretion function caused by interleukin1-β. J Cell Mol Med 2020; 24:14247-14256. [PMID: 33188567 PMCID: PMC7753871 DOI: 10.1111/jcmm.16041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 09/09/2020] [Accepted: 09/18/2020] [Indexed: 12/21/2022] Open
Abstract
Islet inflammation severely impairs pancreatic β‐cell function, but the specific mechanisms are still unclear. Interleukin1‐β (IL‐1β), an essential inflammatory factor, exerts a vital role in multiple physio‐pathologic processes, including diabetes. Calcium/calmodulin‐dependent serine protein kinase (CASK) is an important regulator especially in insulin secretion process. This study aims to unveil the function of CASK in IL‐1β–induced insulin secretion dysfunction and the possible mechanism thereof. Islets of Sprague‐Dawley (SD) rats and INS‐1 cells stimulated with IL‐1β were utilized as models of chronic inflammation. Insulin secretion function associated with Cask and DNA methyltransferases (DNMT) expression were assessed. The possible mechanisms of IL‐1β‐induced pancreatic β‐cell dysfunction were also explored. In this study, CASK overexpression effectively improved IL‐1β‐induced islet β‐cells dysfunction, increased insulin secretion. DNA methyltransferases and the level of methylation in the promoter region of Cask were elevated after IL‐1β administration. Methyltransferase inhibitor 5‐Aza‐2’‐deoxycytidine (5‐Aza‐dC) and si‐DNMTs partially up‐regulated CASK expression and reversed potassium stimulated insulin secretion (KSIS) and glucose‐stimulated insulin secretion (GSIS) function under IL‐1β treatment in INS‐1 and rat islets. These results reveal a previously unknown effect of IL‐1β on insulin secretion dysfunction and demonstrate a novel pathway for Cask silencing based on activation of DNA methyltransferases via inducible nitric oxide synthase (iNOS) and modification of gene promoter methylation.
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Affiliation(s)
- Tian-Yuan Wang
- Department of Endocrinology, Zhongda Hospital, Institute of Diabetes, School of Medicine, Southeast University, Nanjing, China
| | - Xing-Jing Liu
- Department of Endocrinology, Zhongda Hospital, Institute of Diabetes, School of Medicine, Southeast University, Nanjing, China
| | - Jin-Yang Xie
- Department of Endocrinology, Zhongda Hospital, Institute of Diabetes, School of Medicine, Southeast University, Nanjing, China
| | - Qing-Zhao Yuan
- Department of Endocrinology, Zhongda Hospital, Institute of Diabetes, School of Medicine, Southeast University, Nanjing, China
| | - Yao Wang
- Department of Endocrinology, Zhongda Hospital, Institute of Diabetes, School of Medicine, Southeast University, Nanjing, China
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9
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Zhang X, Guan T, Yang B, Gu HF, Chi Z. Effects of ZnT8 on epithelial-to-mesenchymal transition and tubulointerstitial fibrosis in diabetic kidney disease. Cell Death Dis 2020; 11:544. [PMID: 32681069 PMCID: PMC7367835 DOI: 10.1038/s41419-020-2731-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 06/21/2020] [Accepted: 06/25/2020] [Indexed: 12/31/2022]
Abstract
Zinc transporter 8 (ZnT8) transports zinc ions for crystallization and storage of insulin in pancreatic beta-cells and ZnT8 dysfunction is involved in pathogenesis of diabetes. The current study aimed to investigate whether ZnT8 has effects in pathophysiology of diabetic kidney disease (DKD) by using animal models for diabetes, including STZ-induced diabetic, db/db, ZnT8-KO, ZnT8-KO-STZ and ZnT8-KO-db/db mice. Results demonstrated that urine albumin to creatinine ratio and epithelial-to-mesenchymal transition (EMT) were increased in kidneys of ZnT8-KO-STZ and ZnT8-KO-db/db mice compared with C57BL/6 J and ZnT8-KO mice, while serum TGF-β1, IL-6, and TNF-α levels were elevated in parallel. In kidneys of mice intercrossed between ZnT8-KO and STZ-induced diabetic or db/db mice, these three inflammatory factors, ACR and EMT were also found to be increased compared with C57BL/6J, db/db and ZnT8-KO mice. Furthermore, ZnT8 up-regulation by hZnT8-EGFP reduced the levels of high glucose (HG)-induced EMT and inflammatory factors in normal rat kidney tubular epithelial cell (NRK-52E cells). Expression of phosphorylated Smad2/Smad3 was up-regulated after HG stimulation and further enhanced by ZnT8 siRNA but down-regulated after hZnT8-EGFP gene transfection. The current study thus provides the first evidence that ZnT8 protects against EMT-tubulointerstitial fibrosis though the restrain of TGF-β1/Smads signaling activation in DKD.
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Affiliation(s)
- Xiuli Zhang
- Department of Nephrology, Second People's Hospital, The First Affiliated Hospital of Shenzhen University, 518000, Shenzhen, Guangdong Province, P.R. China.,Department of Pathophysiology, China Medical University, 110001, Shenyang, Liaoning Province, P.R. China
| | - Tingwen Guan
- Department of Pathophysiology, China Medical University, 110001, Shenyang, Liaoning Province, P.R. China
| | - Boxuan Yang
- Department of Pathophysiology, China Medical University, 110001, Shenyang, Liaoning Province, P.R. China
| | - Harvest F Gu
- Center for Pathophysiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, 210009, Nanjing, Jiangsu Province, P.R. China.
| | - Zhihong Chi
- Department of Pathophysiology, China Medical University, 110001, Shenyang, Liaoning Province, P.R. China.
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10
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Merriman C, Fu D. Down-regulation of the islet-specific zinc transporter-8 (ZnT8) protects human insulinoma cells against inflammatory stress. J Biol Chem 2019; 294:16992-17006. [PMID: 31591269 DOI: 10.1074/jbc.ra119.010937] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/04/2019] [Indexed: 12/31/2022] Open
Abstract
Zinc transporter-8 (ZnT8) primarily functions as a zinc-sequestrating transporter in the insulin-secretory granules (ISGs) of pancreatic β-cells. Loss-of-function mutations in ZnT8 are associated with protection against type-2 diabetes (T2D), but the protective mechanism is unclear. Here, we developed an in-cell ZnT8 assay to track endogenous ZnT8 responses to metabolic and inflammatory stresses applied to human insulinoma EndoC-βH1 cells. Unexpectedly, high glucose and free fatty acids did not alter cellular ZnT8 levels, but proinflammatory cytokines acutely, reversibly, and gradually down-regulated ZnT8. Approximately 50% of the cellular ZnT8 was localized to the endoplasmic reticulum (ER), which was the primary target of the cytokine-mediated ZnT8 down-regulation. Transcriptome profiling of cytokine-exposed β-cells revealed an adaptive unfolded protein response (UPR) including a marked immunoproteasome activation that coordinately degraded ZnT8 and insulin over a 1,000-fold cytokine concentration range. RNAi-mediated ZnT8 knockdown protected cells against cytokine cytotoxicity, whereas inhibiting immunoproteasomes blocked cytokine-induced ZnT8 degradation and triggered a transition of the adaptive UPR to cell apoptosis. Hence, cytokine-induced down-regulation of the ER ZnT8 level promotes adaptive UPR, acting as a protective mechanism that decongests the ER burden of ZnT8 to protect β-cells from proapoptotic UPR during chronic low-grade inflammation.
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Affiliation(s)
- Chengfeng Merriman
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
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11
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Giacconi R, Malavolta M, Chiodi L, Boccoli G, Costarelli L, Bonfigli AR, Galeazzi R, Piacenza F, Basso A, Gasparini N, Nisi L, Testa R, Provinciali M. ZnT8 Arg325Trp polymorphism influences zinc transporter expression and cytokine production in PBMCs from patients with diabetes. Diabetes Res Clin Pract 2018; 144:102-110. [PMID: 30142362 DOI: 10.1016/j.diabres.2018.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/13/2018] [Accepted: 08/01/2018] [Indexed: 12/30/2022]
Abstract
AIMS ZnT8 Arg325Trp polymorphism has been associated with type 2 diabetes (T2DM) susceptibility. The Arg-325 risk variant shows accelerated zinc (Zn) transport kinetic and reduced glucose-stimulated insulin secretion in pancreatic cells. However, it remains unexplored the role of Znt8 polymorphism in the regulation of Zn homeostasis and inflammatory response in peripheral blood mononuclear cells (PBMCs) from T2DM patients. METHODS AND RESULTS A total of 556 healthy controls and 413 T2DM patients were genotyped for ZnT8 Arg325Trp polymorphism confirming the association of Arg-325 variant with an increased T2DM risk (OR = 1.35 95% C.I: 1.10-1.66; p = 0.0044). Moreover, PBMCs from Arg/Arg T2DM subjects showed increased intracellular free Zn, higher gene expression of Metallothioneins, Znt1, Znt8, Zip2 genes, and reduced Znt4 and Znt7. Higher release of IL-1α, IL-1β, IFN-γ, IL-12p70 and TNF-α and a reduced IL-10 secretion after lipopolysaccharide (LPS) stimulation were observed in PBMCs from Arg/Arg T2DM carriers as compared to subjects with the Trp variant. CONCLUSIONS Our data provide evidence of a substantial different Zn homeostasis regulation between Znt8 Arg-325 and Trp-325 carriers in PBMCs from T2DM patients. Moreover, Znt8 Arg-325 risk variant shows an enhanced inflammatory response upon LPS stimulation that might aggravate insulin resistance and the progression of diabetes cardiovascular complications.
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Affiliation(s)
- R Giacconi
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy.
| | - M Malavolta
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - L Chiodi
- Department of General and Vascular Surgery, INRCA-IRCCS, Ancona, Italy
| | - G Boccoli
- Department of General and Vascular Surgery, INRCA-IRCCS, Ancona, Italy
| | - L Costarelli
- Clinical Laboratory & Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
| | - A R Bonfigli
- Scientific Direction, INRCA-IRCCS National Institute, Ancona, Italy
| | - R Galeazzi
- Clinical Laboratory & Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
| | - F Piacenza
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - A Basso
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - N Gasparini
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - L Nisi
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - R Testa
- Clinical Laboratory & Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
| | - M Provinciali
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
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12
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Human umbilical cord-derived mesenchymal stem cells direct macrophage polarization to alleviate pancreatic islets dysfunction in type 2 diabetic mice. Cell Death Dis 2018; 9:760. [PMID: 29988034 PMCID: PMC6037817 DOI: 10.1038/s41419-018-0801-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 05/13/2018] [Accepted: 06/01/2018] [Indexed: 12/14/2022]
Abstract
Progressive pancreatic β-cell dysfunction is recognized as a fundamental pathology of type 2 diabetes (T2D). Recently, mesenchymal stem cells (MSCs) have been identified in protection of islets function in T2D individuals. However, the underlying mechanisms remain elusive. It is widely accepted that β-cell dysfunction is closely related to improper accumulation of macrophages in the islets, and a series of reports suggest that MSCs possess great immunomodulatory properties by which they could elicit macrophages into an anti-inflammatory M2 state. In this study, we induced a T2D mouse model with a combination of high-fat diet (HFD) and low-dose streptozotocin (STZ), and then performed human umbilical cord-derived MSCs (hUC-MSCs) infusion to investigate whether the effect of MSCs on islets protection was related to regulation on macrophages in pancreatic islets. hUC-MSCs infusion exerted anti-diabetic effects and significantly promoted islets recovery in T2D mice. Interestingly, pancreatic inflammation was remarkably suppressed, and local M1 macrophages were directed toward an anti-inflammatory M2-like state after hUC-MSC infusion. In vitro study also proved that hUC-MSCs inhibited the activation of the M1 phenotype and induced the generation of the M2 phenotype in isolated mouse bone marrow-derived macrophages (BMDMs), peritoneal macrophages (PMs) and in THP-1 cells. Further analysis showed that M1-stimulated hUC-MSCs increased the secretion of interleukin (IL)-6, blocking which by small interfering RNA (siRNA) largely abrogated the hUC-MSCs effects on macrophages both in vitro and in vivo, resulting in dampened restoration of β-cell function and glucose homeostasis in T2D mice. In addition, MCP-1 was found to work in accordance with IL-6 in directing macrophage polarization from M1 to M2 state. These data may provide new clues for searching for the target of β-cell protection. Furthermore, hUC-MSCs may be a superior alternative in treating T2D for their macrophage polarization effects.
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13
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Giacconi R, Cai L, Costarelli L, Cardelli M, Malavolta M, Piacenza F, Provinciali M. Implications of impaired zinc homeostasis in diabetic cardiomyopathy and nephropathy. Biofactors 2017; 43:770-784. [PMID: 28845600 DOI: 10.1002/biof.1386] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/12/2017] [Accepted: 07/27/2017] [Indexed: 12/18/2022]
Abstract
Impaired zinc homeostasis is observed in diabetes mellitus (DM2) and its complications. Zinc has a specific role in pancreatic β-cells via insulin synthesis, storage, and secretion. Intracellular zinc homeostasis is tightly controlled by zinc transporters (ZnT and Zip families) and metallothioneins (MT) which modulate the uptake, storage, and distribution of zinc. Several investigations in animal models demonstrate the protective role of MT in DM2 and its cardiovascular or renal complications, while a copious literature shows that a common polymorphism (R325W) in ZnT8, which affects the protein's zinc transport activity, is associated with increased DM2 risk. Emerging studies highlight a role of other zinc transporters in β-cell function, suggesting that targeting them could make a possible contribution in managing the hyperglycemia in diabetic patients. This article summarizes the current findings concerning the role of zinc homeostasis in DM2 pathogenesis and development of diabetic cardiomyopathy and nephropathy and suggests novel therapeutic targets. © 2017 BioFactors, 43(6):770-784, 2017.
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Affiliation(s)
- Robertina Giacconi
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Lu Cai
- Pediatric Research Institute at the Department of Pediatrics, Wendy L. Novak Diabetes Care Center, University of Louisville, Louisville, KY, USA
| | - Laura Costarelli
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Maurizio Cardelli
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Marco Malavolta
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Francesco Piacenza
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Mauro Provinciali
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
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14
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Elseweidy MM, Ali AMA, Elabidine NZ, Mursey NM. Effect of zinc gluconate, sage oil on inflammatory patterns and hyperglycemia in zinc deficient diabetic rats. Biomed Pharmacother 2017; 95:317-323. [PMID: 28858729 DOI: 10.1016/j.biopha.2017.08.081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 08/18/2017] [Accepted: 08/21/2017] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The relationship between zinc homeostasis and pancreatic function had been established. In this study we aimed firstly to configure the inflammatory pattern and hyperglycemia in zinc deficient diabetic rats. Secondly to illustrate the effect of two selected agents namely Zinc gluconate and sage oil (Salvia Officinalis, family Lamiaceae). METHODS Rats were fed on Zinc deficient diet, deionized water for 28days along with Zinc level check up at intervals to achieve zinc deficient state then rats were rendered diabetic through receiving one dose of alloxan monohydrate (120mg/kg) body weight, classified later into 5 subgroups. RESULTS Treatment with sage oil (0.042mg/kg IP) and Zinc gluconate orally (150mg/kg) body weight daily for 8 weeks significantly reduced serum glucose, C-reactive protein (CRP), Tumor necrosis factor alpha (TNF- α), interleukins-6 1 β, inflammatory8 (IFN ȣ), pancreatic 1L1-β along with an increase in serum Zinc and pancreatic Zinc transporter 8 (ZNT8). Histopathological results of pancreatic tissues showed a good correlation with the biochemical findings. CONCLUSIONS Both sage oil and zinc gluconate induced an improvement in the glycemic and inflammatory states. This may be of value like the therapeutic agent for diabetes.
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Affiliation(s)
- Mohamed M Elseweidy
- Department of Biochemistry, Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt.
| | - Abdel-Moniem A Ali
- Department of Pathology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44519, Egypt.
| | - Nabila Zein Elabidine
- Department of Biochemistry, Faculty of Sciences, Zagazig University, Zagazig 44519, Egypt.
| | - Nada M Mursey
- Department of Biochemistry, Faculty of Sciences, Zagazig University, Zagazig 44519, Egypt.
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15
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Wong WP, Allen NB, Meyers MS, Link EO, Zhang X, MacRenaris KW, El Muayed M. Exploring the Association Between Demographics, SLC30A8 Genotype, and Human Islet Content of Zinc, Cadmium, Copper, Iron, Manganese and Nickel. Sci Rep 2017; 7:473. [PMID: 28352089 PMCID: PMC5428289 DOI: 10.1038/s41598-017-00394-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 02/23/2017] [Indexed: 12/30/2022] Open
Abstract
A widely prevalent single nucleotide polymorphism, rs13266634 in the SLC30A8 gene encoding the zinc transporter ZnT8, is associated with an increased risk for T2DM. ZnT8 is mostly expressed in pancreatic insulin-producing islets of Langerhans. The effect of this variant on the divalent metal profile in human islets is unknown. Additionally, essential and non-essential divalent metal content of human islets under normal environmental exposure conditions has not been described. We therefore examined the correlation of zinc and other divalent metals in human islets with rs13266634 genotype and demographic characteristics. We found that the diabetes risk genotype C/C at rs13266634 is associated with higher islet Zn concentration (C/C genotype: 16792 ± 1607, n = 22, C/T genotype: 11221 ± 1245, n = 18 T/T genotype: 11543 ± 6054, n = 3, all values expressed as mean nmol/g protein ± standard error of the mean, p = 0.040 by ANOVA). A positive correlation between islet cadmium content and both age (p = 0.048, R2 = 0.09) and female gender (women: 36.88 ± 4.11 vs men: 21.22 ± 3.65 nmol/g protein, p = 0.007) was observed. Our results suggest that the T2DM risk allele C is associated with higher islet zinc levels and support prior evidence of cadmium's higher bioavailability in women and its long tissue half-life.
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Affiliation(s)
- Winifred P Wong
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Norrina B Allen
- Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Matthew S Meyers
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Emma O Link
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Xiaomin Zhang
- Division of Transplant Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Keith W MacRenaris
- The Chemistry of Life Processes Institute and Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Malek El Muayed
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
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16
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Huang Q, Merriman C, Zhang H, Fu D. Coupling of Insulin Secretion and Display of a Granule-resident Zinc Transporter ZnT8 on the Surface of Pancreatic Beta Cells. J Biol Chem 2017; 292:4034-4043. [PMID: 28130446 DOI: 10.1074/jbc.m116.772152] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 01/24/2017] [Indexed: 01/14/2023] Open
Abstract
The islet-specific zinc transporter ZnT8 mediates zinc enrichment in the insulin secretory granules of the pancreatic beta cell. This granular zinc transporter is also a major self-antigen found in type 1 diabetes patients. It is not clear whether ZnT8 can be displayed on the cell surface and how insulin secretion may regulate the level of ZnT8 exposure to extracellular immune surveillance. Here we report specific antibody binding to the extracellular surface of rat insulinoma INS-1E cells that stably expressed a tagged human zinc transporter ZnT8. Flow cytometry analysis after fluorescent antibody labeling revealed strong correlations among the levels of ZnT8 expression, its display on the cell surface, and glucose-stimulated insulin secretion (GSIS). Glucose stimulation increased the surface display of endogenous ZnT8 from a basal level to 32.5% of the housekeeping Na+/K+ ATPase on the cell surface, thereby providing direct evidence for a GSIS-dependent surface exposure of the ZnT8 self-antigen. Moreover, the variation in tagged-ZnT8 expression and surface labeling enabled sorting of heterogeneous beta cells to subpopulations that exhibited marked differences in GSIS with parallel changes in endogenous ZnT8 expression. The abundant surface display of endogenous ZnT8 and its coupling to GSIS demonstrated the potential of ZnT8 as a surface biomarker for tracking and isolating functional beta cells in mixed cell populations.
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Affiliation(s)
- Qiong Huang
- From the Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Chengfeng Merriman
- From the Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Hao Zhang
- From the Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Dax Fu
- From the Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
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17
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Coffey R, Knutson MD. The plasma membrane metal-ion transporter ZIP14 contributes to nontransferrin-bound iron uptake by human β-cells. Am J Physiol Cell Physiol 2016; 312:C169-C175. [PMID: 27903581 DOI: 10.1152/ajpcell.00116.2016] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 11/09/2016] [Accepted: 11/23/2016] [Indexed: 01/01/2023]
Abstract
The relationship between iron and β-cell dysfunction has long been recognized as individuals with iron overload display an increased incidence of diabetes. This link is usually attributed to the accumulation of excess iron in β-cells leading to cellular damage and impaired function. Yet, the molecular mechanism(s) by which human β-cells take up iron has not been determined. In the present study, we assessed the contribution of the metal-ion transporters ZRT/IRT-like protein 14 and 8 (ZIP14 and ZIP8) and divalent metal-ion transporter-1 (DMT1) to iron uptake by human β-cells. Iron was provided to the cells as nontransferrin-bound iron (NTBI), which appears in the plasma during iron overload and is a major contributor to tissue iron loading. We found that overexpression of ZIP14 and ZIP8, but not DMT1, resulted in increased NTBI uptake by βlox5 cells, a human β-cell line. Conversely, siRNA-mediated knockdown of ZIP14, but not ZIP8, resulted in 50% lower NTBI uptake in βlox5 cells. In primary human islets, knockdown of ZIP14 also reduced NTBI uptake by 50%. Immunofluorescence analysis of islets from human pancreatic sections localized ZIP14 and DMT1 nearly exclusively to β-cells. Studies in primary human islets suggest that ZIP14 protein levels do not vary with iron status or treatment with IL-1β. Collectively, these observations identify ZIP14 as a major contributor to NTBI uptake by β-cells and suggest differential regulation of ZIP14 in primary human islets compared with other cell types such as hepatocytes.
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Affiliation(s)
- Richard Coffey
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida
| | - Mitchell D Knutson
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida
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18
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Cheng L, Zhang D, Chen B. Tumor necrosis factor α-induced protein-3 protects zinc transporter 8 against proinflammatory cytokine-induced downregulation. Exp Ther Med 2016; 12:1509-1514. [PMID: 27588072 DOI: 10.3892/etm.2016.3457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/15/2016] [Indexed: 12/12/2022] Open
Abstract
Zinc transporter 8 (ZnT8) is exclusively expressed in the pancreatic islet and is essential for insulin crystallization, hexamerization and secretion. Tumor necrosis factor α-induced protein-3 (TNFAIP3) is a zinc finger protein that serves a major role in the negative feedback regulation of NF-κB signaling in response to multiple stimuli, and is a central regulator of immunopathology. Although the role of TNFAIP3 in diabetes has been extensively studied, its effect on ZnT8 has not been fully elucidated. The present study aimed to verify whether proinflammatory cytokines, tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β), are able to affect ZnT8 expression in islet cells. In addition, the study aimed to determine the effect of TNFAIP3 overexpression on cytokine-altered ZnT8 activity, considering its effect on NF-κB signaling. Cell-based studies using NIT-1 cells overexpressing TNFAIP3 were used to assess the effect of cytokines on ZnT8 and NF-κB activation, as well as the effect of TNFAIP3 on ZnT8 expression. Western blot analysis and immunofluorescence staining were employed to determine the protein expression and NF-κB activation, respectively. The results indicated that cytokine stimulation led to TNFAIP3 upregulation, ZnT8 downregulation and NF-κB activation. Furthermore, TNFAIP3 overexpression protected ZnT8 from cytokine-induced downregulation. In conclusion, the current results suggest that inflammation or TNFAIP3 dysfunction may be involved in the pathogenesis of diabetes via ZnT8 expression, besides from islet cell apoptosis. In addition, restricting inflammation and enhancing TNFAIP3 expression may exert a positive effect in diabetes prevention, treatment and pancreatic cell transplantation.
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Affiliation(s)
- Liqing Cheng
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
| | - Dongmei Zhang
- Department of Dermatology, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
| | - Bing Chen
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
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19
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Yi B, Huang G, Zhou ZG. Current and Future Clinical Applications of Zinc Transporter-8 in Type 1 Diabetes Mellitus. Chin Med J (Engl) 2016; 128:2387-94. [PMID: 26315089 PMCID: PMC4733793 DOI: 10.4103/0366-6999.163389] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Objective: To evaluate the utility of zinc transporter-8 (ZnT8) in the improvement of type 1 diabetes mellitus (T1DM) diagnosis and prediction, and to explore whether ZnT8 is a potential therapeutic target in T1DM. Data Sources: A search was conducted within the medical database PubMed for relevant articles published from 2001 to 2015. The search terms are as follows: “ZnT8,” “type 1 diabetes,” “latent autoimmune diabetes in adults,” “type 2 diabetes,” “islet autoantibodies,” “zinc supplement,” “T cells,” “β cell,” “immune therapy.” We also searched the reference lists of selected articles. Study Selection: English-language original articles and critical reviews concerning ZnT8 and the clinical applications of islet autoantibodies in diabetes were reviewed. Results: The basic function of ZnT8 is maintaining intracellular zinc homeostasis, which modulates the process of insulin biosynthesis, storage, and secretion. Autoantibodies against ZnT8 (ZnT8A) and ZnT8-specific T cells are the reliable biomarkers for the identification, stratification, and characterization of T1DM. Additionally, the results from the animal models and clinical trials have shown that ZnT8 is a diabetogenic antigen, suggesting the possibility of ZnT8-specific immunotherapy as an alternative for T1DM therapy. Conclusions: ZnT8 is a novel islet autoantigen with a widely potential for clinical applications in T1DM. However, before the large-scale clinical applications, there are still many problems to be solved.
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Affiliation(s)
| | | | - Zhi-Guang Zhou
- Institute of Metabolism and Endocrinology, Second Xiangya Hospital, Central South University, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, Changsha, Hunan 410011, China
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20
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Giacomelli R, Ruscitti P, Alvaro S, Ciccia F, Liakouli V, Di Benedetto P, Guggino G, Berardicurti O, Carubbi F, Triolo G, Cipriani P. IL-1β at the crossroad between rheumatoid arthritis and type 2 diabetes: may we kill two birds with one stone? Expert Rev Clin Immunol 2016; 12:849-55. [PMID: 26999417 DOI: 10.1586/1744666x.2016.1168293] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Although in the past the prevention of joint destruction in rheumatoid arthritis (RA) was strongly emphasized, now a great interest is focused on associated comorbidities in these patients. Multiple data suggest that a large percentage of RA patients are affected by Type 2 Diabetes (T2D), whose incidence has reached epidemic levels in recent years, thus increasing the health care costs. A better knowledge about the pathogenesis of these diseases as well as the mechanisms of action of drugs may allow both policy designers and physicians to choose the most effective treatments, thus lowering the costs. This review will focus on the role of Interleukin (IL)-1β in the pathogenesis of both the diseases, the efficacy of IL-1 blocking molecules in controlling these diseases, and will provide information suggesting that targeting IL-1β, in patients affected by both RA and T2D, may be a promising therapeutic choice.
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Affiliation(s)
- Roberto Giacomelli
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Piero Ruscitti
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Saverio Alvaro
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Francesco Ciccia
- b Division of Rheumatology, Department of Internal Medicine , University of Palermo , Palermo , Italy
| | - Vasiliki Liakouli
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Paola Di Benedetto
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Giuliana Guggino
- b Division of Rheumatology, Department of Internal Medicine , University of Palermo , Palermo , Italy
| | - Onorina Berardicurti
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Francesco Carubbi
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
| | - Giovanni Triolo
- b Division of Rheumatology, Department of Internal Medicine , University of Palermo , Palermo , Italy
| | - Paola Cipriani
- a Division of Rheumatology, Department of Biotechnological and Applied Clinical Science , School of Medicine, University of L'Aquila , L'Aquila , Italy
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21
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Imaging trace element distributions in single organelles and subcellular features. Sci Rep 2016; 6:21437. [PMID: 26911251 PMCID: PMC4766485 DOI: 10.1038/srep21437] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 01/15/2016] [Indexed: 12/30/2022] Open
Abstract
The distributions of chemical elements within cells are of prime importance in a wide range of basic and applied biochemical research. An example is the role of the subcellular Zn distribution in Zn homeostasis in insulin producing pancreatic beta cells and the development of type 2 diabetes mellitus. We combined transmission electron microscopy with micro- and nano-synchrotron X-ray fluorescence to image unequivocally for the first time, to the best of our knowledge, the natural elemental distributions, including those of trace elements, in single organelles and other subcellular features. Detected elements include Cl, K, Ca, Co, Ni, Cu, Zn and Cd (which some cells were supplemented with). Cell samples were prepared by a technique that minimally affects the natural elemental concentrations and distributions, and without using fluorescent indicators. It could likely be applied to all cell types and provide new biochemical insights at the single organelle level not available from organelle population level studies.
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Somboonwong J, Traisaeng S, Saguanrungsirikul S. Moderate-intensity exercise training elevates serum and pancreatic zinc levels and pancreatic ZnT8 expression in streptozotocin-induced diabetic rats. Life Sci 2015; 139:46-51. [DOI: 10.1016/j.lfs.2015.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/16/2015] [Accepted: 08/01/2015] [Indexed: 01/17/2023]
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Cheng L, Zhang D, Jiang Y, Deng W, Wu Q, Jiang X, Chen B. Decreased A20 mRNA and protein expression in peripheral blood mononuclear cells in patients with type 2 diabetes and latent autoimmune diabetes in adults. Diabetes Res Clin Pract 2014; 106:611-6. [PMID: 25451900 DOI: 10.1016/j.diabres.2014.09.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 09/04/2014] [Accepted: 09/15/2014] [Indexed: 12/23/2022]
Abstract
AIMS A20 is a negative regulator of nuclear factor kappa B activation and the central gatekeeper in inflammation and immunity. While its role in type 1 diabetes has been widely studied, its expression level in immune cells from type 2 diabetes (T2D) and latent autoimmune diabetes in adult (LADA) patients remains unclear. This study aimed to clarify whether the expression of A20 is altered in patients with T2D or LADA. METHODS Quantitative real-time polymerase chain reaction and western blotting were utilized to determine the expression of A20 mRNA and protein respectively in peripheral blood mononuclear cells (PBMCs) from patients with T2D (n=36) or LADA (n=17) and sex- and age-matched healthy controls (n=34). RESULTS The mRNA and protein expression of A20 in PBMCs from T2D and LADA patients was significantly decreased compared with healthy controls (P<0.05). Furthermore, A20 mRNA and protein expression was significantly lower in newly diagnosed T2D patients (≤1 year since diagnosis) than in patients with a long T2D duration (>1 year since diagnosis) (P<0.05). CONCLUSIONS Our results suggest that decreased expression of A20 in PBMCs may be involved in the pathogenesis of diabetes, and targeting A20 may offer a potential therapeutic tool in the treatment of diabetes.
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Affiliation(s)
- Liqing Cheng
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Dongmei Zhang
- Department of Dermatology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Youzhao Jiang
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Wuquan Deng
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Qi'nan Wu
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Xiaoyan Jiang
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Bing Chen
- Department of Endocrinology and Metabolism, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
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Gerber PA, Bellomo EA, Hodson DJ, Meur G, Solomou A, Mitchell RK, Hollinshead M, Chimienti F, Bosco D, Hughes SJ, Johnson PRV, Rutter GA. Hypoxia lowers SLC30A8/ZnT8 expression and free cytosolic Zn2+ in pancreatic beta cells. Diabetologia 2014; 57:1635-44. [PMID: 24865615 PMCID: PMC4079946 DOI: 10.1007/s00125-014-3266-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/23/2014] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS Hypoxic damage complicates islet isolation for transplantation and may contribute to beta cell failure in type 2 diabetes. Polymorphisms in the SLC30A8 gene, encoding the secretory granule zinc transporter 8 (ZnT8), influence type 2 diabetes risk, conceivably by modulating cytosolic Zn(2+) levels. We have therefore explored the role of ZnT8 and cytosolic Zn(2+) in the response to hypoxia of pancreatic islet cells. METHODS Human, mouse or rat islets were isolated and exposed to varying O2 tensions. Cytosolic free zinc was measured using the adenovirally expressed recombinant targeted zinc probe eCALWY4. Gene expression was measured using quantitative (q)RT-PCR, western (immuno-) blotting or immunocytochemistry. Beta cells were identified by insulin immunoreactivity. RESULTS Deprivation of O2 (1% vs 5% or 21%) for 24 h lowered free cytosolic Zn(2+) concentrations by ~40% (p < 0.05) and ~30% (p < 0.05) in mouse and human islet cells, respectively. Hypoxia similarly decreased SLC30A8 mRNA expression in islets, and immunoreactivity in beta cells. Implicating lowered ZnT8 levels in the hypoxia-induced fall in cytosolic Zn(2+), genetic ablation of Slc30a8 from mouse islets lowered cytosolic Zn(2+) by ~40% (p < 0.05) and decreased the induction of metallothionein (Mt1, Mt2) genes. Cell survival in the face of hypoxia was enhanced in small islets of older (>12 weeks) Slc30a8 null mice vs controls, but not younger animals. CONCLUSIONS/INTERPRETATION The response of pancreatic beta cells to hypoxia is characterised by decreased SLC30A8 expression and lowered cytosolic Zn(2+) concentrations. The dependence on ZnT8 of hypoxia-induced changes in cell survival may contribute to the actions of SLC30A8 variants on diabetes risk in humans.
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Affiliation(s)
- Philipp A. Gerber
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital Zurich, Zurich, Switzerland
| | - Elisa A. Bellomo
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - David J. Hodson
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Gargi Meur
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Antonia Solomou
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Ryan K. Mitchell
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
| | - Michael Hollinshead
- Section of Microscopy, Department of Medicine, Imperial College London, London, UK
| | | | - Domenico Bosco
- Cell Isolation and Transplantation Centre, Department of Surgery, Geneva University Hospital, Geneva, Switzerland
| | - Stephen J. Hughes
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
- DRWF Human Islet Isolation Facility, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK
- Oxford NIHR Biomedical Research Centre, Oxford, UK
| | - Paul R. V. Johnson
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
- DRWF Human Islet Isolation Facility, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK
- Oxford NIHR Biomedical Research Centre, Oxford, UK
| | - Guy A. Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 ONN UK
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Abstract
Zinc is an essential nutrient with tremendous importance for human health, and zinc deficiency is a severe risk factor for increased mortality and morbidity. As abnormal zinc homeostasis causes diabetes, and because the pancreatic β-cell contains the highest zinc content of any known cell type, it is of interest to know how zinc fluxes are controlled in β-cells. The understanding of zinc homeostasis has been boosted by the discovery of multiprotein families of zinc transporters, and one of them - zinc transporter 8 (ZnT8) - is abundantly and specifically expressed in the pancreatic islets of Langerhans. In this review, we discuss the evidence for a physiological role of ZnT8 in the formation of zinc-insulin crystals, the physical form in which most insulin is stored in secretory granules. In addition, we cross-examine this information, collected in genetically modified mouse strains, to the knowledge that genetic variants of the human ZnT8 gene predispose to the onset of type 2 diabetes and that epitopes on the ZnT8 protein trigger autoimmunity in patients with type 1 diabetes. The overall conclusion is that we are still at the dawn of a complete understanding of how zinc homeostasis operates in normal β-cells and how abnormalities lead to β-cell dysfunction and diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2012.00199.x, 2012).
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Affiliation(s)
- Katleen Lemaire
- Gene Expression Unit, Department of Molecular Cell Biology, KU Leuven, Leuven, Belgium
| | | | - Frans Schuit
- Gene Expression Unit, Department of Molecular Cell Biology, KU Leuven, Leuven, Belgium
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Abstract
Zinc (Zn2+) is an essential element crucial for growth and development, and also plays a role in cell signaling for cellular processes like cell division and apoptosis. In the mammalian pancreas, Zn2+ is essential for the correct processing, storage, secretion, and action of insulin in beta (β)-cells. Insulin is stored inside secretory vesicles or granules, where two Zn2+ ions coordinate six insulin monomers to form the hexameric-structure on which maturated insulin crystals are based. The total Zn2+ content of the mammalian pancreas is among the highest in the body, and Zn2+ concentration reach millimolar levels in the interior of the dense-core granule. Changes in Zn2+ levels in the pancreas have been found to be associated with diabetes. Hence, the relationship between co-stored Zn2+ and insulin undoubtedly is critical to normal β-cell function. The advances in the field of Zn2+ biology over the last decade have facilitated our understanding of Zn2+ trafficking, its intracellular distribution and its storage. When exocytosis of insulin occurs, insulin granules fuse with the β-cell plasma membrane and release their contents, i.e., insulin as well as substantial amount of free Zn2+, into the extracellular space and the local circulation. Studies increasingly indicate that secreted Zn2+ has autocrine or paracrine signaling in β-cells or the neighboring cells. This review discusses the Zn2+ homeostasis in β-cells with emphasis on the potential signaling role of Zn2+ to islet biology.
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Affiliation(s)
- Yang V Li
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, 346 Irvine Hall, Athens, OH, 45701, USA,
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Eguchi K, Manabe I. Macrophages and islet inflammation in type 2 diabetes. Diabetes Obes Metab 2013; 15 Suppl 3:152-8. [PMID: 24003932 DOI: 10.1111/dom.12168] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 04/27/2013] [Indexed: 12/12/2022]
Abstract
Type 2 diabetes (T2D) is characterized by insulin resistance and impaired insulin secretion from pancreatic β-cells. Inflammatory cytokines, including tumour necrosis factor-α (TNF-α), have been shown to promote insulin resistance, and altered expression of cytokines (adipokines) in obese adipose tissue is thought to be an important link between obesity and insulin resistance. It is also becoming clear that inflammation plays a key role in the development of β-cell dysfunction. Inflammatory changes, including accumulation of macrophages, have been documented in T2D islets. Moreover, therapeutic inhibition of interleukin-1β (IL-1β) ameliorates β-cell dysfunction in humans. This review summarizes current understanding of the molecular mechanisms underlying inflammation within islets and its relation to β-cell dysfunction in T2D. A particular focus is on the physiological and pathological functions of macrophages within islets.
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Affiliation(s)
- K Eguchi
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Huang G, Xiang Y, Pan L, Li X, Luo S, Zhou Z. Zinc transporter 8 autoantibody (ZnT8A) could help differentiate latent autoimmune diabetes in adults (LADA) from phenotypic type 2 diabetes mellitus. Diabetes Metab Res Rev 2013; 29:363-8. [PMID: 23390067 DOI: 10.1002/dmrr.2396] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/13/2013] [Accepted: 01/27/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND The ZnT8A is an independent marker for diagnosis of type 1 diabetes mellitus. We investigated the distribution and clinical features of ZnT8A positive latent autoimmune diabetes in adult (LADA) patients to explore the potential diagnostic application. METHODS A total of 3062 phenotypic T2DM patients were randomly selected from a national multicenter study - the LADA China Study. Radioligand binding assays were applied to detect the presence of ZnT8A, GADA and IA-2A. HbA1c , fasting C-peptide and serum lipid levels were followed up with ZnT8A positive patients. RESULTS The positive prevalence of ZnT8A, GADA and IA-2A in phenotypic T2DM patients was 1.99% (61/3062), 6.43% (197/3062) and 1.96% (60/3062), respectively. The ZnT8A positivity was lower than that of GADA(x² = 74.8, p < 0.001) but was comparable with that of IA-2A (p > 0.05). The positivity of ZnT8A in IA-2A positive patients was higher than that in GADA positive patients (38.3% vs. 10.7%, x² = 24.8, p < 0.001). On the basis of GADA and IA-2A positivity, the ZnT8A assay enhanced the diagnostic prevalence of LADA from 7.58 to 8.62%. The LADA patients who were positive for ZnT8A had higher systolic blood pressure when compared with GADA positive cases (p = 0.049) and higher total cholesterol levels when compared with antibody-negative T2DM patients (p = 0.035). CONCLUSION The detection of ZnT8A at the basis of GADA and IA-2A can improve diagnostic sensitivity of Chinese LADA.
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Affiliation(s)
- Gan Huang
- Diabetes Center, Second Xiangya Hospital, and Institute of Metabolism and Endocrinology, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, Hunan Key Laboratory of Medical Epigenomics, Changsha, Hunan, China
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Slepchenko KG, James CBL, Li YV. Inhibitory effect of zinc on glucose-stimulated zinc/insulin secretion in an insulin-secreting β-cell line. Exp Physiol 2013; 98:1301-11. [PMID: 23603373 DOI: 10.1113/expphysiol.2013.072348] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Diminished or inappropriate secretion of insulin is associated with type II diabetes. The cellular/molecular mechanism coupled with the regulation of insulin secretion is still under intense investigation. Divalent ion zinc (Zn(2+)) is co-packaged and co-secreted with insulin and is intimately involved in the process of insulin biosynthesis and the maturation of insulin secretory granules. The study reported here investigated glucose-stimulated zinc secretion (GSZS) and the effect of zinc on glucose-stimulated insulin secretion (GSIS) in the HIT-T15 pancreatic β-cell line. Zinc secretion was measured using a newly developed fluorescent zinc imaging approach, and the insulin secretion was measured using an enzyme-linked immunosorbent assay. There was apparent granular-like zinc staining in β-cells. The application of glucose induced detectable zinc secretion or GSZS. Like GSIS, GSZS was dependent on the glucose concentration (5-20 mm) and the presence of extracellular calcium. The application of a zinc chelator enhanced GSZS. When brief paired-pulse glucose stimulations, which involve the initial glucose stimulation followed by a second round of glucose stimulation, were applied, zinc secretion or GSZS that followed the first pulse was inhibited. This inhibition was reversed by zinc chelation, suggesting a feedback mechanism on GSZS by zinc secreted from β-cells. Finally, the application of zinc (50 μm) strongly inhibited GSIS as measured by enzyme-linked immunosorbent assay. The present study suggests that insulin secretion is regulated by co-secreted zinc that may act as an autocrine inhibitory modulator.
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Affiliation(s)
- Kira G Slepchenko
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, OH 45701, USA
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30
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El Muayed M, Raja MR, Zhang X, MacRenaris KW, Bhatt S, Chen X, Urbanek M, O'Halloran TV, Lowe WL. Accumulation of cadmium in insulin-producing β cells. Islets 2012; 4:405-16. [PMID: 23466887 PMCID: PMC3605169 DOI: 10.4161/isl.23101] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Evidence suggests that chronic low level cadmium exposure impairs the function of insulin-producing β cells and may be associated with type-2 diabetes mellitus. Herein, we describe the cadmium content in primary human islets and define the uptake kinetics and effects of environmentally relevant cadmium concentrations in cultured β cells. The average cadmium content in islets from 10 non-diabetic human subjects was 29 ± 7 nmol/g protein (range 7 to 72 nmol/g protein). Exposure of the β-cell line MIN6 to CdCl 2 concentrations between 0.1 and 1.0 µmol/L resulted in a dose- and time-dependent uptake of cadmium over 72 h. This uptake resulted in an induction of metallthionein expression, likely enhancing cellular cadmium accumulation. Furthermore, cadmium accumulation resulted in an inhibition of glucose stimulated insulin secretion in MIN6 cells and primary mouse islets. Our results indicate that this impairment in β-cell function is not due to an increase in cell death or due to an increase in oxidative stress. We conclude that mouse β cells accumulate cadmium in a dose- and time-dependent manner over a prolonged time course at environmentally relevant concentrations. This uptake leads to a functional impairment of β-cell function without significant alterations in cell viability, expression of genes important for β-cell function or increase in oxidative stress.
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Affiliation(s)
- Malek El Muayed
- Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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31
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Lefebvre B, Vandewalle B, Balavoine AS, Queniat G, Moerman E, Vantyghem MC, Le Bacquer O, Gmyr V, Pawlowski V, Kerr-Conte J, Pattou F. Regulation and functional effects of ZNT8 in human pancreatic islets. J Endocrinol 2012; 214:225-32. [PMID: 22582094 DOI: 10.1530/joe-12-0071] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Zinc ions are essential for the formation of insulin crystals in pancreatic β cells, thereby contributing to packaging efficiency of stored insulin. Zinc fluxes are regulated through the SLC30A (zinc transporter, ZNT) family. Here, we investigated the effect of metabolic stress associated with the prediabetic state (zinc depletion, glucotoxicity, and lipotoxicity) on ZNT expression and human pancreatic islet function. Both zinc depletion and lipotoxicity (but not glucotoxicity) downregulated ZNT8 (SLC30A8) expression and altered the glucose-stimulated insulin secretion index (GSIS). ZNT8 overexpression in human islets protected them from the decrease in GSIS induced by tetrakis-(2-pyridylmethyl) ethylenediamine and palmitate but not from cell death. In addition, zinc supplementation decreased palmitate-induced human islet cell death without restoring GSIS. Altogether, we showed that ZNT8 expression responds to variation in zinc and lipid levels in human β cells, with repercussions on insulin secretion. Prospects for increasing ZNT8 expression and/or activity may prove beneficial in type 2 diabetes in humans.
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Arvan P, Pietropaolo M, Ostrov D, Rhodes CJ. Islet autoantigens: structure, function, localization, and regulation. Cold Spring Harb Perspect Med 2012; 2:cshperspect.a007658. [PMID: 22908193 DOI: 10.1101/cshperspect.a007658] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Islet autoantigens associated with autoimmune type 1 diabetes (T1D) are expressed in pancreatic β cells, although many show wider patterns of expression in the neuroendocrine system. Within pancreatic β cells, every T1D autoantigen is in one way or another linked to the secretory pathway. Together, these autoantigens play diverse roles in glucose regulation, metabolism of biogenic amines, as well as the regulation, formation, and packaging of secretory granules. The mechanism(s) by which immune tolerance to islet-cell antigens is lost during the development of T1D, remains unclear. Antigenic peptide creation for immune presentation may potentially link to the secretory biology of β cells in a number of ways, including proteasomal digestion of misfolded products, exocytosis and endocytosis of cell-surface products, or antigen release from dying β cells during normal or pathological turnover. In this context, we evaluate the biochemical nature and immunogenicity of the major autoantigens in T1D including (pro)insulin, GAD65, ZnT8, IA2, and ICA69.
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Affiliation(s)
- Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105, USA.
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Yang H, Li Q, Lee JH, Shu Y. Reduction in Tcf7l2 expression decreases diabetic susceptibility in mice. Int J Biol Sci 2012; 8:791-801. [PMID: 22719219 PMCID: PMC3372883 DOI: 10.7150/ijbs.4568] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 05/29/2012] [Indexed: 02/02/2023] Open
Abstract
Objective: The WNT signaling pathway effector gene TCF7L2 has been associated with an increased risk of type 2 diabetes. However, it remains unclear how this gene affects diabetic pathogenesis. The goal of this study was to investigate the effects of Tcf7l2 haploinsufficiency on metabolic phenotypes in mice. Experimental Design:Tcf7l2 knockout (Tcf7l-/-) mice were generated. Because of the early mortality of Tcf7l2-/- mice, we characterized the metabolic phenotypes of heterozygous Tcf7l2+/- mice in comparison to the wild-type controls. The mice were fed a normal chow diet or a high fat diet (HFD) for 9 weeks. Results: The Tcf7l2+/- mice showed significant differences from the wild-type mice with regards to body weight, fasting glucose and insulin levels. Tcf7l2+/- mice displayed improved glucose tolerance. In the liver of Tcf7l2+/- mice fed on the HFD, reduced lipogenesis and hepatic triglyceride levels were observed when compared with those of wild-type mice. Furthermore, the Tcf7l2+/- mice fed on the HFD exhibited decreased peripheral fat deposition. Immunohistochemistry in mouse pancreatic islets showed that endogenous expression of Tcf7l2 was upregulated in the wild-type mice, but not in the Tcf7l2+/- mice, after feeding with the HFD. However, the haploinsufficiency of Tcf7l2 in mouse pancreatic islets resulted in little changes in glucose-stimulated insulin secretion. Conclusion: These results suggest that decreased expression of Tcf7l2 confers reduction of diabetic susceptibility in mice via regulation on the metabolism of glucose and lipid.
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Affiliation(s)
- Hyekyung Yang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, USA
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Rising intracellular zinc by membrane depolarization and glucose in insulin-secreting clonal HIT-T15 beta cells. EXPERIMENTAL DIABETES RESEARCH 2012; 2012:190309. [PMID: 22536213 PMCID: PMC3318893 DOI: 10.1155/2012/190309] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/20/2011] [Accepted: 12/23/2011] [Indexed: 11/17/2022]
Abstract
Zinc (Zn2+) appears to be intimately involved in insulin metabolism since insulin secretion is correlated with zinc secretion in response to glucose stimulation, but little is known about the regulation of zinc homeostasis in pancreatic beta-cells. This study set out to identify the intracellular zinc transient by imaging free cytosolic zinc in HIT-T15 beta-cells with fluorescent zinc indicators. We observed that membrane depolarization by KCl (30–60 mM) was able to induce a rapid increase in cytosolic concentration of zinc. Multiple zinc transients of similar magnitude were elicited during repeated stimulations. The amplitude of zinc responses was not affected by the removal of extracellular calcium or zinc. However, the half-time of the rising slope was significantly slower after removing extracellular zinc with zinc chelator CaEDTA, suggesting that extracellular zinc affect the initial rising phase of zinc response. Glucose (10 mM) induced substantial and progressive increases in intracellular zinc concentration in a similar way as KCl, with variation in the onset and the duration of zinc mobilization. It is known that the depolarization of beta-cell membrane is coupled with the secretion of insulin. Rising intracellular zinc concentration may act as a critical signaling factor in insulin metabolism of pancreatic beta-cells.
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Bosco MD, Mohanasundaram DM, Drogemuller CJ, Lang CJ, Zalewski PD, Coates PT. Zinc and zinc transporter regulation in pancreatic islets and the potential role of zinc in islet transplantation. Rev Diabet Stud 2011; 7:263-74. [PMID: 21713314 DOI: 10.1900/rds.2010.7.263] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The critical trace element zinc is essential for normal insulin production, and plays a central role in cellular protection against apoptosis and oxidative stress. The regulation of zinc within the pancreas and β-cells is controlled by the zinc transporter families ZnT and ZIP. Pancreatic islets display wide variability in the occurrence of these molecules. The zinc transporter, ZnT8 is an important target for autoimmunity in type 1 diabetes. Gene polymorphisms of this transporter confer sensitivity for immunosuppressive drugs used in islet transplantation. Understanding the biology of zinc transport within pancreatic islets will provide insight into the mechanisms of β-cell death, and may well reveal new pathways for improvement of diabetes therapy, including islet transplantation. This review discusses the possible roles of zinc in β-cell physiology with a special focus on islet transplantation.
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Affiliation(s)
- Mariea D Bosco
- Central Northern Adelaide Renal and Transplantation Service, Renal and Transplantation Immunology Lab, Royal Adelaide Hospital, South Australia
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37
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El Muayed M, Lowe WL. The beta and alpha cell-specific Znt8-knockout mouse model: new mechanistic insights? Diabetologia 2011; 54:207-8. [PMID: 20953582 DOI: 10.1007/s00125-010-1934-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Accepted: 08/16/2010] [Indexed: 11/29/2022]
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PETERSEN ANDREASB, SMIDT KAMILLE, MAGNUSSON NILSE, MOORE FABRICE, EGEFJORD LAERKE, RUNGBY JØRGEN. siRNA-mediated knock-down of ZnT3 and ZnT8 affects production and secretion of insulin and apoptosis in INS-1E cells. APMIS 2010; 119:93-102. [DOI: 10.1111/j.1600-0463.2010.02698.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
Type 2 diabetes mellitus has been at the forefront of human diseases and phenotypes studied by new genetic analyses. Thanks to genome-wide association studies, we have made substantial progress in elucidating the genetic basis of type 2 diabetes. This review summarizes the concept, history, and recent discoveries produced by genome-wide association studies for type 2 diabetes and glycemic traits, with a focus on the key notions we have gleaned from these efforts. Genome-wide association findings have illustrated novel pathways, pointed toward fundamental biology, confirmed prior epidemiological observations, drawn attention to the role of β-cell dysfunction in type 2 diabetes, explained ~10% of disease heritability, tempered our expectations with regard to their use in clinical prediction, and provided possible targets for pharmacotherapy and pharmacogenetic clinical trials. We can apply these lessons to future investigation so as to improve our understanding of the genetic basis of type 2 diabetes.
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Affiliation(s)
- Liana K. Billings
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
- Diabetes Research Center (Diabetes Unit), Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Jose C. Florez
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
- Diabetes Research Center (Diabetes Unit), Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts
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