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Azzollini L, Prete DD, Wolf G, Klimek C, Saggioro M, Ricci F, Christodoulaki E, Wiedmer T, Ingles-Prieto A, Superti-Furga G, Scarabottolo L. Development of a live cell assay for the zinc transporter ZnT8. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2024; 29:100166. [PMID: 38848895 DOI: 10.1016/j.slasd.2024.100166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 05/27/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024]
Abstract
Zinc is an essential trace element that is involved in many biological processes and in cellular homeostasis. In pancreatic β-cells, zinc is crucial for the synthesis, processing, and secretion of insulin, which plays a key role in glucose homeostasis and which deficiency is the cause of diabetes. The accumulation of zinc in pancreatic cells is regulated by the solute carrier transporter SLC30A8 (or Zinc Transporter 8, ZnT8), which transports zinc from cytoplasm in intracellular vesicles. Allelic variants of SLC30A8 gene have been linked to diabetes. Given the physiological intracellular localization of SLC30A8 in pancreatic β-cells and the ubiquitous endogenous expression of other Zinc transporters in different cell lines that could be used as cellular model for SLC30A8 recombinant over-expression, it is challenging to develop a functional assay to measure SLC30A8 activity. To achieve this goal, we have firstly generated a HEK293 cell line stably overexpressing SLC30A8, where the over-expression favors the partial localization of SLC30A8 on the plasma membrane. Then, we used the combination of this cell model, commercial FluoZin-3 cell permeant zinc dye and live cell imaging approach to follow zinc flux across SLC30A8 over-expressed on plasma membrane, thus developing a novel functional imaging- based assay specific for SLC30A8. Our novel approach can be further explored and optimized, paving the way for future small molecule medium-throughput screening.
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Affiliation(s)
- Lucia Azzollini
- Axxam SpA, Openzone, Via Meucci 3 20091 Bresso, Milan, Italy.
| | | | - Gernot Wolf
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Christoph Klimek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Mattia Saggioro
- Axxam SpA, Openzone, Via Meucci 3 20091 Bresso, Milan, Italy
| | - Fernanda Ricci
- Axxam SpA, Openzone, Via Meucci 3 20091 Bresso, Milan, Italy
| | - Eirini Christodoulaki
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Tabea Wiedmer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Alvaro Ingles-Prieto
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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2
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Chen B, Yu P, Chan WN, Xie F, Zhang Y, Liang L, Leung KT, Lo KW, Yu J, Tse GMK, Kang W, To KF. Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets. Signal Transduct Target Ther 2024; 9:6. [PMID: 38169461 PMCID: PMC10761908 DOI: 10.1038/s41392-023-01679-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 09/15/2023] [Accepted: 10/10/2023] [Indexed: 01/05/2024] Open
Abstract
Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.
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Affiliation(s)
- Bonan Chen
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Peiyao Yu
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangdong Province Key Laboratory of Molecular Tumor Pathology, Guangzhou, China
| | - Wai Nok Chan
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Fuda Xie
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Yigan Zhang
- Institute of Biomedical Research, Taihe Hospital, Hubei University of Medicine, Shiyan, China
| | - Li Liang
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangdong Province Key Laboratory of Molecular Tumor Pathology, Guangzhou, China
| | - Kam Tong Leung
- Department of Pediatrics, The Chinese University of Hong Kong, Hong Kong, China
| | - Kwok Wai Lo
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Jun Yu
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Gary M K Tse
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Wei Kang
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China.
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
| | - Ka Fai To
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China.
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3
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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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Abstract
Since the discovery of manifest Zn deficiency in 1961, the increasing number of studies demonstrated the association between altered Zn status and multiple diseases. In this chapter, we provide a review of the most recent advances on the role of Zn in health and disease (2010-20), with a special focus on the role of Zn in neurodegenerative and neurodevelopmental disorders, diabetes and obesity, male and female reproduction, as well as COVID-19. In parallel with the revealed tight association between ASD risk and severity and Zn status, the particular mechanisms linking Zn2+ and ASD pathogenesis like modulation of synaptic plasticity through ProSAP/Shank scaffold, neurotransmitter metabolism, and gut microbiota, have been elucidated. The increasing body of data indicate the potential involvement of Zn2+ metabolism in neurodegeneration. Systemic Zn levels in Alzheimer's and Parkinson's disease were found to be reduced, whereas its sequestration in brain may result in modulation of amyloid β and α-synuclein processing with subsequent toxic effects. Zn2+ was shown to possess adipotropic effects through the role of zinc transporters, zinc finger proteins, and Zn-α2-glycoprotein in adipose tissue physiology, underlying its particular role in pathogenesis of obesity and diabetes mellitus type 2. Recent findings also contribute to further understanding of the role of Zn2+ in spermatogenesis and sperm functioning, as well as oocyte development and fertilization. Finally, Zn2+ was shown to be the potential adjuvant therapy in management of novel coronavirus infection (COVID-19), underlining the perspectives of zinc in management of old and new threats.
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Affiliation(s)
- Anatoly V Skalny
- IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; Yaroslavl State University, Yaroslavl, Russia
| | - Michael Aschner
- IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Alexey A Tinkov
- IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; Yaroslavl State University, Yaroslavl, Russia.
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Barragán-Álvarez CP, Padilla-Camberos E, Díaz NF, Cota-Coronado A, Hernández-Jiménez C, Bravo-Reyna CC, Díaz-Martínez NE. Loss of Znt8 function in diabetes mellitus: risk or benefit? Mol Cell Biochem 2021; 476:2703-2718. [PMID: 33666829 DOI: 10.1007/s11010-021-04114-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
The zinc transporter 8 (ZnT8) plays an essential role in zinc homeostasis inside pancreatic β cells, its function is related to the stabilization of insulin hexameric form. Genome-wide association studies (GWAS) have established a positive and negative relationship of ZnT8 variants with type 2 diabetes mellitus (T2DM), exposing a dual and controversial role. The first hypotheses about its role in T2DM indicated a higher risk of developing T2DM for loss of function; nevertheless, recent GWAS of ZnT8 loss-of-function mutations in humans have shown protection against T2DM. With regard to the ZnT8 role in T2DM, most studies have focused on rodent models and common high-risk variants; however, considerable differences between human and rodent models have been found and the new approaches have included lower-frequency variants as a tool to clarify gene functions, allowing a better understanding of the disease and offering possible therapeutic targets. Therefore, this review will discuss the physiological effects of the ZnT8 variants associated with a major and lower risk of T2DM, emphasizing the low- and rare-frequency variants.
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Affiliation(s)
- Carla P Barragán-Álvarez
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Eduardo Padilla-Camberos
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Nestor F Díaz
- Departamento de Fisiología y Desarrollo Celular, Instituto Nacional de Perinatología, Mexico City, Mexico
| | - Agustín Cota-Coronado
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Claudia Hernández-Jiménez
- Departamento de Cirugía Experimental, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Carlos C Bravo-Reyna
- Departamento de Cirugía Experimental, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Nestor E Díaz-Martínez
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico.
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6
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Dzianová P, Asai S, Chrudinová M, Kosinová L, Potalitsyn P, Šácha P, Hadravová R, Selicharová I, Kříž J, Turkenburg JP, Brzozowski AM, Jiráček J, Žáková L. The efficiency of insulin production and its content in insulin-expressing model β-cells correlate with their Zn 2+ levels. Open Biol 2020; 10:200137. [PMID: 33081637 PMCID: PMC7653362 DOI: 10.1098/rsob.200137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 09/24/2020] [Indexed: 12/29/2022] Open
Abstract
Insulin is produced and stored inside the pancreatic β-cell secretory granules, where it is assumed to form Zn2+-stabilized oligomers. However, the actual storage forms of this hormone and the impact of zinc ions on insulin production in vivo are not known. Our initial X-ray fluorescence experiment on granules from native Langerhans islets and insulinoma-derived INS-1E cells revealed a considerable difference in the zinc content. This led our further investigation to evaluate the impact of the intra-granular Zn2+ levels on the production and storage of insulin in different model β-cells. Here, we systematically compared zinc and insulin contents in the permanent INS-1E and BRIN-BD11 β-cells and in the native rat pancreatic islets by flow cytometry, confocal microscopy, immunoblotting, specific messenger RNA (mRNA) and total insulin analysis. These studies revealed an impaired insulin production in the permanent β-cell lines with the diminished intracellular zinc content. The drop in insulin and Zn2+ levels was paralleled by a lower expression of ZnT8 zinc transporter mRNA and hampered proinsulin processing/folding in both permanent cell lines. To summarize, we showed that the disruption of zinc homeostasis in the model β-cells correlated with their impaired insulin and ZnT8 production. This indicates a need for in-depth fundamental research about the role of zinc in insulin production and storage.
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Affiliation(s)
- Petra Dzianová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Seiya Asai
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University, 12840 Prague 2, Czech Republic
| | - Martina Chrudinová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Lucie Kosinová
- Laboratory of Pancreatic Islets, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague, Czech Republic
| | - Pavlo Potalitsyn
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University, 12840 Prague 2, Czech Republic
| | - Pavel Šácha
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Romana Hadravová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Jan Kříž
- Laboratory of Pancreatic Islets, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague, Czech Republic
| | - Johan P. Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Andrzej Marek Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
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Syring KE, Bosma KJ, Goleva SB, Singh K, Oeser JK, Lopez CA, Skaar EP, McGuinness OP, Davis LK, Powell DR, O’Brien RM. Potential positive and negative consequences of ZnT8 inhibition. J Endocrinol 2020; 246:189-205. [PMID: 32485672 PMCID: PMC7351606 DOI: 10.1530/joe-20-0138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/02/2020] [Indexed: 12/31/2022]
Abstract
SLC30A8 encodes the zinc transporter ZnT8. SLC30A8 haploinsufficiency protects against type 2 diabetes (T2D), suggesting that ZnT8 inhibitors may prevent T2D. We show here that, while adult chow fed Slc30a8 haploinsufficient and knockout (KO) mice have normal glucose tolerance, they are protected against diet-induced obesity (DIO), resulting in improved glucose tolerance. We hypothesize that this protection against DIO may represent one mechanism whereby SLC30A8 haploinsufficiency protects against T2D in humans and that, while SLC30A8 is predominantly expressed in pancreatic islet beta cells, this may involve a role for ZnT8 in extra-pancreatic tissues. Consistent with this latter concept we show in humans, using electronic health record-derived phenotype analyses, that the 'C' allele of the non-synonymous rs13266634 SNP, which confers a gain of ZnT8 function, is associated not only with increased T2D risk and blood glucose, but also with increased risk for hemolytic anemia and decreased mean corpuscular hemoglobin (MCH). In Slc30a8 KO mice, MCH was unchanged but reticulocytes, platelets and lymphocytes were elevated. Both young and adult Slc30a8 KO mice exhibit a delayed rise in insulin after glucose injection, but only the former exhibit increased basal insulin clearance and impaired glucose tolerance. Young Slc30a8 KO mice also exhibit elevated pancreatic G6pc2 gene expression, potentially mediated by decreased islet zinc levels. These data indicate that the absence of ZnT8 results in a transient impairment in some aspects of metabolism during development. These observations in humans and mice suggest the potential for negative effects associated with T2D prevention using ZnT8 inhibitors.
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Affiliation(s)
- Kristen E. Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Karin J. Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Slavina B. Goleva
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Kritika Singh
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Christopher A. Lopez
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Eric P. Skaar
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Lea K. Davis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - David R. Powell
- Lexicon Pharmaceuticals Incorporated, 8800 Technology Forest Place, The Woodlands, Texas 77381
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
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8
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Daniels MJ, Jagielnicki M, Yeager M. Structure/Function Analysis of human ZnT8 (SLC30A8): A Diabetes Risk Factor and Zinc Transporter. Curr Res Struct Biol 2020; 2:144-155. [PMID: 34235474 PMCID: PMC8244513 DOI: 10.1016/j.crstbi.2020.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 06/15/2020] [Accepted: 06/22/2020] [Indexed: 12/17/2022] Open
Abstract
The human zinc transporter ZnT8 (SLC30A8) is expressed primarily in pancreatic β-cells and plays a key function in maintaining the concentration of blood glucose through its role in insulin storage, maturation and secretion. ZnT8 is an autoantigen for Type 1 diabetes (T1D) and is associated with Type 2 diabetes (T2D) through its risk allele that encodes a major non-synonymous single nucleotide polymorphism (SNP) at Arg325. Loss of function mutations improve insulin secretion and are protective against diabetes. Despite its role in diabetes and concomitant potential as a drug target, little is known about the structure or mechanism of ZnT8. To this end, we expressed ZnT8 in Pichia pastoris yeast and Sf9 insect cells. Guided by a rational screen of 96 detergents, we developed a method to solubilize and purify recombinant ZnT8. An in vivo transport assay in Pichia and a liposome-based uptake assay for insect-cell derived ZnT8 showed that the protein is functionally active in both systems. No significant difference in activity was observed between full-length ZnT8 (ZnT8A) and the amino-terminally truncated ZnT8B isoform. A fluorescence-based in vitro transport assay using proteoliposomes indicated that human ZnT8 functions as a Zn2+/H+ antiporter. We also purified E. coli-expressed amino- and carboxy-terminal cytoplasmic domains of ZnT8A. Circular dichroism spectrometry suggested that the amino-terminal domain contains predominantly α-helical structure, and indicated that the carboxy-terminal domain has a mixed α/β structure. Negative-stain electron microscopy and single-particle image analysis yielded a density map of ZnT8B at 20 Å resolution, which revealed that ZnT8 forms a dimer in detergent micelles. Two prominent lobes are ascribed to the transmembrane domains, and the molecular envelope recapitulates that of the bacterial zinc transporter YiiP. These results provide a foundation for higher resolution structural studies and screening experiments to identify compounds that modulate ZnT8 activity.
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Affiliation(s)
- Mark J. Daniels
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Maciej Jagielnicki
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Biochemistry, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Virginia Health System, Charlottesville, VA, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
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9
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The zinc transporter Zip14 (SLC39a14) affects Beta-cell Function: Proteomics, Gene expression, and Insulin secretion studies in INS-1E cells. Sci Rep 2019; 9:8589. [PMID: 31197210 PMCID: PMC6565745 DOI: 10.1038/s41598-019-44954-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 05/24/2019] [Indexed: 12/18/2022] Open
Abstract
Insulin secretion from pancreatic beta-cells is dependent on zinc ions as essential components of insulin crystals, zinc transporters are thus involved in the insulin secretory process. Zip14 (SLC39a14) is a zinc importing protein that has an important role in glucose homeostasis. Zip14 knockout mice display hyperinsulinemia and impaired insulin secretion in high glucose conditions. Endocrine roles for Zip14 have been established in adipocytes and hepatocytes, but not yet confirmed in beta-cells. In this study, we investigated the role of Zip14 in the INS-1E beta-cell line. Zip14 mRNA was upregulated during high glucose stimulation and Zip14 silencing led to increased intracellular insulin content. Large-scale proteomics showed that Zip14 silencing down-regulated ribosomal mitochondrial proteins, many metal-binding proteins, and others involved in oxidative phosphorylation and insulin secretion. Furthermore, proliferation marker Mki67 was down-regulated in Zip14 siRNA-treated cells. In conclusion, Zip14 gene expression is glucose sensitive and silencing of Zip14 directly affects insulin processing in INS-1E beta-cells. A link between Zip14 and ribosomal mitochondrial proteins suggests altered mitochondrial RNA translation, which could disturb mitochondrial function and thereby insulin secretion. This highlights a role for Zip14 in beta-cell functioning and suggests Zip14 as a future pharmacological target in the treatment of beta-cell dysfunction.
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10
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Cai Y, Kirschke CP, Huang L. SLC30A family expression in the pancreatic islets of humans and mice: cellular localization in the β-cells. J Mol Histol 2018; 49:133-145. [DOI: 10.1007/s10735-017-9753-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 12/30/2017] [Indexed: 10/18/2022]
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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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12
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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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13
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Analysis of Zinc-Exporters Expression in Prostate Cancer. Sci Rep 2016; 6:36772. [PMID: 27833104 PMCID: PMC5105060 DOI: 10.1038/srep36772] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 10/20/2016] [Indexed: 01/15/2023] Open
Abstract
Maintaining optimal intracellular zinc (Zn) concentration is crucial for critical cellular functions. Depleted Zn has been associated with prostate cancer (PCa) progression. Solute carrier family 30 (SLC30A) proteins maintain cytoplasmic Zn balance by exporting Zn out to the extracellular space or by sequestering cytoplasmic Zn into intracellular compartments. In this study, we determined the involvement of Zn-exporters, SLC30A 1-10 in PCa, in the context of racial health disparity in human PCa samples obtained from European-American (EA) and African-American (AA) populations. We also analyzed the levels of Zn-exporters in a panel of PCa cells derived from EA and AA populations. We further explored the expression profile of Zn-exporters in PCa using Oncomine database. Zn-exporters were found to be differentially expressed at the mRNA level, with a significant upregulation of SLC30A1, SLC30A9 and SLC30A10, and downregulation of SLC30A5 and SLC30A6 in PCa, compared to benign prostate. Moreover, Ingenuity Pathway analysis revealed several interactions of Zn-exporters with certain tumor suppressor and promoter proteins known to be modulated in PCa. Our study provides an insight regarding Zn-exporters in PCa, which may open new avenues for future studies aimed at enhancing the levels of Zn by modulating Zn-transporters via pharmacological means.
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The zinc transporter ZNT3 co-localizes with insulin in INS-1E pancreatic beta cells and influences cell survival, insulin secretion capacity, and ZNT8 expression. Biometals 2016; 29:287-98. [DOI: 10.1007/s10534-016-9915-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 02/05/2016] [Indexed: 01/21/2023]
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Byun HR, Choi JA, Koh JY. The role of metallothionein-3 in streptozotocin-induced beta-islet cell death and diabetes in mice. Metallomics 2015; 6:1748-57. [PMID: 25054451 DOI: 10.1039/c4mt00143e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Metallothionein-3 (Mt3), a zinc (Zn)-regulatory protein mainly expressed in the central nervous system, may contribute to oxidative cell death. In the present study, we examined the possible role of Mt3 in streptozotocin (STZ)-induced islet cell death and consequent hyperglycemia. Quantitative real-time polymerase chain reaction (RT-PCR) confirmed that islet cells expressed Mt3 mRNA. In all cases, wild-type (WT) mice injected with STZ exhibited hyperglycemia 7-21 days later. In stark contrast, all Mt3-null mice remained normoglycemic following STZ injection. STZ treatment increased free Zn levels in islet cells and induced their death in WT mice, but failed to do so in Mt3-null mice. Consistent with this, cultured Mt3-null islet cells exhibited striking resistance to STZ toxicity. Notably, PDE3a (phosphodiesterase 3A) was downregulated in islets of Mt3-null mice compared to those of WT mice, and was not induced by STZ treatment. Moreover, the PDE3 inhibitor cilostazol reduced islet cell death, likely by increasing cAMP levels, further supporting a role for PDE3 in STZ-induced islet cell death. Collectively, these results demonstrate that Mt3 may act through PDE3a to play a key role in Zn dyshomeostasis and cell death in STZ-treated islets.
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Affiliation(s)
- Hyae-Ran Byun
- Neural Injury Research Center, Asan Institute for Life Science, University of Ulsan College of Medicine, Seoul, Korea
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16
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Davidson HW, Wenzlau JM, O'Brien RM. Zinc transporter 8 (ZnT8) and β cell function. Trends Endocrinol Metab 2014; 25:415-24. [PMID: 24751356 PMCID: PMC4112161 DOI: 10.1016/j.tem.2014.03.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 03/17/2014] [Accepted: 03/19/2014] [Indexed: 02/07/2023]
Abstract
Human pancreatic β cells have exceptionally high zinc content. In β cells the highest zinc concentration is in insulin secretory granules, from which it is cosecreted with the hormone. Uptake of zinc into secretory granules is mainly mediated by zinc transporter 8 (ZnT8), the product of the SLC30A8 [solute carrier family 30 (zinc transporter), member 8] gene. The minor alleles of several single-nucleotide polymorphisms (SNPs) in SLC30A8 are associated with decreased risk of type 2 diabetes (T2D), but the precise mechanisms underlying the protective effects remain uncertain. In this article we review current knowledge of the role of ZnT8 in maintaining zinc homeostasis in β cells, its role in glucose metabolism based on knockout mouse studies, and current theories regarding the link between ZnT8 function and T2D.
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Affiliation(s)
- Howard W Davidson
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA; Integrated Department of Immunology, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Janet M Wenzlau
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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Nygaard SB, Larsen A, Knuhtsen A, Rungby J, Smidt K. Effects of zinc supplementation and zinc chelation on in vitro β-cell function in INS-1E cells. BMC Res Notes 2014; 7:84. [PMID: 24502363 PMCID: PMC3923740 DOI: 10.1186/1756-0500-7-84] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 02/04/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Zinc is essential for the activities of pancreatic β-cells, especially insulin storage and secretion. Insulin secretion leads to co-release of zinc which contributes to the paracrine communication in the pancreatic islets. Zinc-transporting proteins (zinc-regulated transporter, iron-regulated transporter-like proteins [ZIPs] and zinc transporters [ZnTs]) and metal-buffering proteins (metallothioneins, MTs) tightly regulate intracellular zinc homeostasis. The present study investigated how modulation of cellular zinc availability affects β-cell function using INS-1E cells. RESULTS Using INS-1E cells, we found that zinc supplementation and zinc chelation had significant effects on insulin content and insulin secretion. Supplemental zinc within the physiological concentration range induced insulin secretion. Insulin content was reduced by zinc chelation with N,N,N',N-tektrakis(2-pyridylmethyl)-ethylenediamine. The changes in intracellular insulin content following exposure to various concentrations of zinc were reflected by changes in the expression patterns of MT-1A, ZnT-8, ZnT-5, and ZnT-3. Furthermore, high zinc concentrations induced cell necrosis while zinc chelation induced apoptosis. Finally, cell proliferation was sensitive to changes in zinc the concentration. CONCLUSION These results indicate that the β-cell-like function and survival of INS-1E cells are dependent on the surrounding zinc concentrations. Our results suggest that regulation of zinc homeostasis could represent a pharmacological target.
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Affiliation(s)
- Sanne Bjørn Nygaard
- Department of Biomedicine, Centre of Pharmacology and Pharmacotherapy, Health, Aarhus University, Wilhelm Meyers Allé 4, Bld 1240, Aarhus, 8000, Denmark.
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Huang L. Zinc and its transporters, pancreatic β-cells, and insulin metabolism. VITAMINS AND HORMONES 2014; 95:365-90. [PMID: 24559925 DOI: 10.1016/b978-0-12-800174-5.00014-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Zinc is an essential trace metal for life. Two families of zinc transporters, SLC30A (ZNT) and SLC39A (ZIP) are required for maintaining cellular zinc homeostasis. ZNTs function to decrease cytoplasmic zinc concentrations whereas ZIPs do the opposite. Expression of zinc transporters can be tissue/cell-type specific or ubiquitous. Zinc transporters that are limited in tissue/cell distributions usually perform specialized tasks to satisfy biological processes in a given cell. For example, ZNT8 is mainly expressed in β-cells and functions to deliver zinc into granules for insulin maturation and secretion. Many other zinc transporters are also expressed in β-cells. Defects in these zinc transporters have been associated with abnormalities in insulin synthesis, maturation, and secretion and subsequent glucose metabolism. This review focuses on the specific roles of zinc and its transporters in insulin metabolism and describes the current knowledge of the function of zinc transporters in β-cell health in animal knockout mouse models with respect to diabetes development in humans.
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Affiliation(s)
- Liping Huang
- United States Department of Agriculture/Agricultural Research Service/Western Human Nutrition Research Center, Obesity and Metabolism Research Unit, Davis, California, USA; Department of Nutrition, University of California Davis, Davis, California, USA.
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ZnT7 can protect MC3T3-E1 cells from oxidative stress-induced apoptosis via PI3K/Akt and MAPK/ERK signaling pathways. Cell Signal 2013; 25:1126-35. [DOI: 10.1016/j.cellsig.2013.02.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 02/02/2013] [Accepted: 02/04/2013] [Indexed: 11/18/2022]
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Abstract
Zn is an essential trace element, involved in many different cellular processes. A relationship between Zn, pancreatic function and diabetes was suggested almost 70 years ago. To emphasise the importance of Zn in biology, the history of Zn research in the field of diabetes along with a general description of Zn transporter families will be reviewed. The paper will then focus on the effects of Zn on pancreatic β-cell function, including insulin synthesis and secretion, Zn signalling in the pancreatic islet, the redox functions of Zn and its target genes. The recent association of two ‘Zn genes’, i.e. metallothionein (MT) and Zn transporter 8 (SLC 30A8), with type 2 diabetes at the genetic level and with insulin secretion in clinical studies offers a potential new way to identify new drug targets to modulate Zn homeostasis directly in β-cells. The action of Zn for insulin action in its target organs, as Zn signalling in other pancreatic islet cells, will be addressed. Therapeutic Zn–insulin preparations and the influence of Zn and Zn transporters in type 1 diabetes will also be discussed. An extensive review of the literature on the clinical studies using Zn supplementation in the prevention and treatment of both types of diabetes, including complications of the disease, will evaluate the overall beneficial effects of Zn supplementation on blood glucose control, suggesting that Zn might be a candidate ion for diabetes prevention and therapy. Clearly, the story of the links between Zn, pancreatic islet cells and diabetes is only now unfolding, and we are presently only at the first chapter.
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Myers SA, Nield A, Myers M. Zinc transporters, mechanisms of action and therapeutic utility: implications for type 2 diabetes mellitus. J Nutr Metab 2012; 2012:173712. [PMID: 23304467 PMCID: PMC3530793 DOI: 10.1155/2012/173712] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/07/2012] [Accepted: 11/07/2012] [Indexed: 12/29/2022] Open
Abstract
Zinc is an essential trace element that plays a vital role in maintaining many biological processes and cellular homeostasis. Dysfunctional zinc signaling is associated with a number of chronic disease states including cancer, cardiovascular disease, Alzheimer's disease, and diabetes. Cellular homeostasis requires mechanisms that tightly control the uptake, storage, and distribution of zinc. This is achieved through the coordinated actions of zinc transporters and metallothioneins. Evidence on the role of these proteins in type 2 diabetes mellitus (T2DM) is now emerging. Zinc plays a key role in the synthesis, secretion and action of insulin in both physiological and pathophysiological states. Moreover, recent studies highlight zinc's dynamic role as a "cellular second messenger" in the control of insulin signaling and glucose homeostasis. This suggests that zinc plays an unidentified role as a novel second messenger that augments insulin activity. This previously unexplored concept would raise a whole new area of research into the pathophysiology of insulin resistance and introduce a new class of drug target with utility for diabetes pharmacotherapy.
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Affiliation(s)
- Stephen A. Myers
- School of Health Sciences, University of Ballarat, University Drive, Mount Helen, VIC 3350, Australia
- Collaborative Research Network, University of Ballarat, Mount Helen, VIC 3350, Australia
| | - Alex Nield
- School of Health Sciences, University of Ballarat, University Drive, Mount Helen, VIC 3350, Australia
| | - Mark Myers
- School of Health Sciences, University of Ballarat, University Drive, Mount Helen, VIC 3350, Australia
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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: 69] [Impact Index Per Article: 5.8] [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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24
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Smidt K, Rungby J. ZnT3: a zinc transporter active in several organs. Biometals 2011; 25:1-8. [DOI: 10.1007/s10534-011-9490-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 08/17/2011] [Indexed: 12/30/2022]
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25
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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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