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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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2
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Pan CY, Lin FY, Kao LS, Huang CC, Liu PS. Zinc oxide nanoparticles modulate the gene expression of ZnT1 and ZIP8 to manipulate zinc homeostasis and stress-induced cytotoxicity in human neuroblastoma SH-SY5Y cells. PLoS One 2020; 15:e0232729. [PMID: 32915786 PMCID: PMC7485861 DOI: 10.1371/journal.pone.0232729] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 08/27/2020] [Indexed: 11/19/2022] Open
Abstract
Zinc ions (Zn2+) are important messenger molecules involved in various physiological functions. To maintain the homeostasis of cytosolic Zn2+ concentration ([Zn2+]c), Zrt/Irt-related proteins (ZIPs) and Zn2+ transporters (ZnTs) are the two families of proteins responsible for decreasing and increasing the [Zn2+]c, respectively, by fluxing Zn2+ across the membranes of the cell and intracellular compartments in opposite directions. Most studies focus on the cytotoxicity incurred by a high concentration of [Zn2+]c and less investigate the [Zn2+]c at physiological levels. Zinc oxide-nanoparticle (ZnO-NP) is blood brain barrier-permeable and elevates the [Zn2+]c to different levels according to the concentrations of ZnO-NP applied. In this study, we mildly elevated the [Zn2+]c by ZnO-NP at concentrations below 1 μg/ml, which had little cytotoxicity, in cultured human neuroblastoma SH-SY5Y cells and characterized the importance of Zn2+ transporters in 6-hydroxy dopamine (6-OHDA)-induced cell death. The results show that ZnO-NP at low concentrations elevated the [Zn2+]c transiently in 6 hr, then declined gradually to a basal level in 24 hr. Knocking down the expression levels of ZnT1 (located mostly at the plasma membrane) and ZIP8 (present in endosomes and lysosomes) increased and decreased the ZnO-NP-induced elevation of [Zn2+]c, respectively. ZnO-NP treatment reduced the basal levels of reactive oxygen species and Bax/Bcl-2 mRNA ratios; in addition, ZnO-NP decreased the 6-OHDA-induced ROS production, p53 expression, and cell death. These results show that ZnO-NP-induced mild elevation in [Zn2+]c activates beneficial effects in reducing the 6-OHDA-induced cytotoxic effects. Therefore, brain-delivery of ZnO-NP can be regarded as a potential therapy for neurodegenerative diseases.
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Affiliation(s)
- Chien-Yuan Pan
- Department of Life Science and Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Fang-Yu Lin
- Department of Microbiology, Soochow University, Taipei, Taiwan
| | - Lung-Sen Kao
- Brain Research Center, National Yang-Ming University, Taipei, Taiwan
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Chien-Chang Huang
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Pei-Shan Liu
- Department of Microbiology, Soochow University, Taipei, Taiwan
- * E-mail:
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Bossowski A, Stożek K, Rydzewska M, Niklińska W, Gąsowska M, Polnik D, Szalecki M, Mikłosz A, Chabowski A, Reszeć J. Expression of zinc transporter 8 in thyroid tissues from patients with immune and non-immune thyroid diseases. Autoimmunity 2020; 53:376-384. [PMID: 32896170 DOI: 10.1080/08916934.2020.1815194] [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] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Recent studies have revealed the presence of zinc and the expression of zinc transporter (ZnT) family members in most endocrine cell types. It was demonstrated that ZnT family plays an important role in the synthesis and secretion of many hormones. Moreover, recently ZnT8 was described as a newly islet autoantigen in type 1 diabetes. MATERIALS AND METHODS We studied the expression of ZnT8 transporter in thyroid tissues from patients with immune and non-immune thyroid diseases. The study was performed in thyroid tissues after thyroidectomy from patients with thyroid non-toxic nodular goitre (NTNG; n = 17, mean age 15.8 ± 2.2 years) and cases with Graves' disease (n = 20, mean age 15.6 ± 2.8). In our study we investigated the expression of ZnT8 in human thyroid tissues from patients with immune and non-immune thyroid diseases using immunohistochemistry, Western Blot as well as immunofluorescence analyses. To the best of our knowledge, this is the first investigation which identified ZnT8 protein expression in human thyroid tissues, moreover, confirmed by three different laboratory techniques. Results and Conclusions Expression of ZnT8 transporter was identified by immunohistochemistry in the thyroid tissues from paediatric patients with Graves' disease (on +++) and non-toxic nodular goitre (on ++). ZnT8 transporter expression was found both in thyroid follicular cells (within the cytoplasm and cytoplasmic membrane in follicular cells) and C cells (membrane-cytoplasmic reaction) in fluorescence. Predominant expression of ZnT8 in band 41 kDa in immune than in non-immune thyroid disorders may suggest potential role of ZnT8 as a new thyroid autoanitgen but it requires further study on a larger cohort.
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Affiliation(s)
- Artur Bossowski
- Department of Pediatrics, Endocrinology and Diabetes with a Cardiology Unit, Medical University of Bialystok, Bialystok, Poland
| | - Karolina Stożek
- Department of Pediatrics, Endocrinology and Diabetes with a Cardiology Unit, Medical University of Bialystok, Bialystok, Poland
| | - Marta Rydzewska
- Department of Pediatrics, Endocrinology and Diabetes with a Cardiology Unit, Medical University of Bialystok, Bialystok, Poland
| | - Wiesława Niklińska
- Department of Histology and Embryology, Medical University of Bialystok, Bialystok, Poland
| | - Marta Gąsowska
- Department of Histology and Embryology, Medical University of Bialystok, Bialystok, Poland
| | - Dariusz Polnik
- Department of Children's Surgery and Transplantology, Children's Memorial Health Institute, Warsaw, Poland
| | - Mieczysław Szalecki
- Department of Pediatric Endocrinology and Diabetology, Children's Memorial Health Institute, Warsaw, Poland
| | - Agnieszka Mikłosz
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
| | - Joanna Reszeć
- Department of Medical Patomorphology, Medical University of Bialystok, Bialystok, Poland
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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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Severo JS, Morais JBS, de Freitas TEC, Andrade ALP, Feitosa MM, Fontenelle LC, de Oliveira ARS, Cruz KJC, do Nascimento Marreiro D. The Role of Zinc in Thyroid Hormones Metabolism. INT J VITAM NUTR RES 2019; 89:80-88. [DOI: 10.1024/0300-9831/a000262] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Abstract. Thyroid hormones play an important role in body homeostasis by facilitating metabolism of lipids and glucose, regulating metabolic adaptations, responding to changes in energy intake, and controlling thermogenesis. Proper metabolism and action of these hormones requires the participation of various nutrients. Among them is zinc, whose interaction with thyroid hormones is complex. It is known to regulate both the synthesis and mechanism of action of these hormones. In the present review, we aim to shed light on the regulatory effects of zinc on thyroid hormones. Scientific evidence shows that zinc plays a key role in the metabolism of thyroid hormones, specifically by regulating deiodinases enzymes activity, thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH) synthesis, as well as by modulating the structures of essential transcription factors involved in the synthesis of thyroid hormones. Serum concentrations of zinc also appear to influence the levels of serum T3, T4 and TSH. In addition, studies have shown that Zinc transporters (ZnTs) are present in the hypothalamus, pituitary and thyroid, but their functions remain unknown. Therefore, it is important to further investigate the roles of zinc in regulation of thyroid hormones metabolism, and their importance in the treatment of several diseases associated with thyroid gland dysfunction.
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Affiliation(s)
- Juliana Soares Severo
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | - Jennifer Beatriz Silva Morais
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | | | - Ana Letícia Pereira Andrade
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | - Mayara Monte Feitosa
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | - Larissa Cristina Fontenelle
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | - Ana Raquel Soares de Oliveira
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | - Kyria Jayanne Clímaco Cruz
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
| | - Dilina do Nascimento Marreiro
- Nutrition Department, Federal University of Piauí, Campus Minister Petrônio Portella, Ininga, Teresina, Piauí, Brazil
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Guantario B, Capolupo A, Monti MC, Leoni G, Ranaldi G, Tosco A, Marzullo L, Murgia C, Perozzi G. Proteomic Analysis of Zn Depletion/Repletion in the Hormone-Secreting Thyroid Follicular Cell Line FRTL-5. Nutrients 2018; 10:nu10121981. [PMID: 30558183 PMCID: PMC6315927 DOI: 10.3390/nu10121981] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 12/14/2022] Open
Abstract
Zinc deficiency predisposes to a wide spectrum of chronic diseases. The human Zn proteome was predicted to represent about 10% of the total human proteome, reflecting the broad array of metabolic functions in which this micronutrient is known to participate. In the thyroid, Zn was reported to regulate cellular homeostasis, with a yet elusive mechanism. The Fischer Rat Thyroid Cell Line FRTL-5 cell model, derived from a Fischer rat thyroid and displaying a follicular cell phenotype, was used to investigate a possible causal relationship between intracellular Zn levels and thyroid function. A proteomic approach was applied to compare proteins expressed in Zn deficiency, obtained by treating cells with the Zn-specific chelator N,N,N′,N′-tetrakis (2-pyridylmethyl) ethylene-diamine (TPEN), with Zn repleted cells. Quantitative proteomic analysis of whole cell protein extracts was performed using stable isotope dimethyl labelling coupled to nano-ultra performance liquid chromatography-mass spectrometry (UPLC-MS). TPEN treatment led to almost undetectable intracellular Zn, while decreasing thyroglobulin secretion. Subsequent addition of ZnSO4 fully reversed these phenotypes. Comparative proteomic analysis of Zn depleted/repleted cells identified 108 proteins modulated by either treatment. Biological process enrichment analysis identified functions involved in calcium release and the regulation of translation as the most strongly regulated processes in Zn depleted cells.
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Affiliation(s)
- Barbara Guantario
- Research Centre for Food and Nutrition, CREA, Via Ardeatina 546, 00178 Rome, Italy.
| | - Angela Capolupo
- Department of Pharmacy, Division of Chemistry & Chemical Technologies "Luigi Gomez Paloma", University of Salerno, Via Giovanni Paolo II, 132 84084 Fisciano (SA), Italy.
| | - Maria Chiara Monti
- Department of Pharmacy, Division of Chemistry & Chemical Technologies "Luigi Gomez Paloma", University of Salerno, Via Giovanni Paolo II, 132 84084 Fisciano (SA), Italy.
| | - Guido Leoni
- Nouscom, via di Castel Romano 100, 00128 Rome, Italy.
| | - Giulia Ranaldi
- Research Centre for Food and Nutrition, CREA, Via Ardeatina 546, 00178 Rome, Italy.
| | - Alessandra Tosco
- Department of Pharmacy Biomedical Division "Arturo Leone", University of Salerno, Via Giovanni Paolo II, 132 84084 Fisciano (SA), Italy.
| | - Liberato Marzullo
- Department of Medicine, Surgery and Dentistry "Schola Medica Salernitana", University of Salerno, Via Salvador Allende, 84081 Baronissi (SA), Italy.
| | - Chiara Murgia
- Department of Nutrition, Dietetics and Food, Monash University, Melbourne, VIC 3168, Australia.
| | - Giuditta Perozzi
- Research Centre for Food and Nutrition, CREA, Via Ardeatina 546, 00178 Rome, Italy.
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7
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Zhang X, Guan T, Yang B, Chi Z, Wang ZY, Gu HF. A novel role for zinc transporter 8 in the facilitation of zinc accumulation and regulation of testosterone synthesis in Leydig cells of human and mouse testicles. Metabolism 2018; 88:40-50. [PMID: 30236453 DOI: 10.1016/j.metabol.2018.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/05/2018] [Accepted: 09/11/2018] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Zinc is intimately involved in testosterone production. Zinc transporter 8 (ZnT8) is found to be localized in insulin secretory granules as a β-cell specific Zn transporter. The effect of ZnT8 and related zinc accumulation in steroidogenesis, however, is still unknown. The present study aimed to explore whether ZnT8 plays a role in the facilitation of zinc accumulation and regulation of testosterone synthesis in testicles. METHODS Leydig cells were isolated from the testicles of human, CD-1 suckling and ZnT8-KO mice. Zn accumulation in mitochondria was induced by hCG stimulation. Transfection of hZnT8-EGFP and RNA interfere of mZnT8 were done in MLTC-1 cells. ZnT8 expression and its co-localization with steroidogenic acute regulatory (StAR) protein were analyzed with RT-PCR, Western blot and dual-fluorescent staining protocols. Serum testosterone levels in mice were determined with chemiluminescent enzyme immunoassay. RESULTS ZnT8 was found to be presented in Leydig cells and up-regulated in suckling mouse Leydig cells and MLTC-1 cells after hCG administration, by which zinc accumulation occurred in mitochondria. ZnT8 gene silencing or knockout inhibited stimulated progesterone and testosterone production, reduced stimulated zinc accumulation and down-regulated phosphorylated steroidogenic acute regulatory (StAR) expression in Leydig cells. Furthermore, an inhibitor (H89) of PKA blocked hCG-stimulated progesterone caused by ZnT8 over-expression and zinc treatment. CONCLUSION The present study provided the first evidence that ZnT8 transports Zn into Leydig cell mitochondria with gonadotropin stimulation and suggests that ZnT8 may play a role in testosterone production via the PKA signaling pathway.
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Affiliation(s)
- Xiuli Zhang
- Department of Nephrology, The second People's Hospital, Shenzhen, The first Affiliated Hospital of Shenzhen University, Guangdong 518000, PR China; Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China
| | - Tingwen Guan
- Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China
| | - Boxuan Yang
- Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China
| | - Zhihong Chi
- Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China.
| | - Zhan-You Wang
- College of Life and Health Sciences, China Medical University, Shenyang, Liaoning 110001, PR China
| | - Harvest F Gu
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, PR China.
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8
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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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9
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Hutchens S, Liu C, Jursa T, Shawlot W, Chaffee BK, Yin W, Gore AC, Aschner M, Smith DR, Mukhopadhyay S. Deficiency in the manganese efflux transporter SLC30A10 induces severe hypothyroidism in mice. J Biol Chem 2017; 292:9760-9773. [PMID: 28461334 DOI: 10.1074/jbc.m117.783605] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/27/2017] [Indexed: 12/31/2022] Open
Abstract
Manganese is an essential metal that becomes toxic at elevated levels. Loss-of-function mutations in SLC30A10, a cell-surface-localized manganese efflux transporter, cause a heritable manganese metabolism disorder resulting in elevated manganese levels and parkinsonian-like movement deficits. The underlying disease mechanisms are unclear; therefore, treatment is challenging. To understand the consequences of loss of SLC30A10 function at the organism level, we generated Slc30a10 knock-out mice. During early development, knock-outs were indistinguishable from controls. Surprisingly, however, after weaning and compared with controls, knock-out mice failed to gain weight, were smaller, and died prematurely (by ∼6-8 weeks of age). At 6 weeks, manganese levels in the brain, blood, and liver of the knock-outs were ∼20-60-fold higher than controls. Unexpectedly, histological analyses revealed that the brain and liver of the knock-outs were largely unaffected, but their thyroid exhibited extensive alterations. Because hypothyroidism leads to growth defects and premature death in mice, we assayed for changes in thyroid and pituitary hormones. At 6 weeks and compared with controls, the knock-outs had markedly reduced thyroxine levels (∼50-80%) and profoundly increased thyroid-stimulating hormone levels (∼800-1000-fold), indicating that Slc30a10 knock-out mice develop hypothyroidism. Importantly, a low-manganese diet produced lower tissue manganese levels in the knock-outs and rescued the phenotype, suggesting that manganese toxicity was the underlying cause. Our unanticipated discovery highlights the importance of determining the role of thyroid dysfunction in the onset and progression of manganese-induced disease and identifies Slc30a10 knock-out mice as a new model for studying thyroid biology.
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Affiliation(s)
- Steven Hutchens
- From the Division of Pharmacology & Toxicology, College of Pharmacy, Institute for Cellular & Molecular Biology, and Institute for Neuroscience and
| | - Chunyi Liu
- From the Division of Pharmacology & Toxicology, College of Pharmacy, Institute for Cellular & Molecular Biology, and Institute for Neuroscience and
| | - Thomas Jursa
- the Department of Microbiology and Environmental Toxicology, University of California at Santa Cruz, Santa Cruz, California 95064
| | - William Shawlot
- the Mouse Genetic Engineering Facility, Institute for Cellular & Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Beth K Chaffee
- the Department of Veterinary Sciences, Michale E. Keeling Center for Comparative Medicine and Research, M. D. Anderson Cancer Center, Bastrop, Texas 78602, and
| | - Weiling Yin
- From the Division of Pharmacology & Toxicology, College of Pharmacy, Institute for Cellular & Molecular Biology, and Institute for Neuroscience and
| | - Andrea C Gore
- From the Division of Pharmacology & Toxicology, College of Pharmacy, Institute for Cellular & Molecular Biology, and Institute for Neuroscience and
| | - Michael Aschner
- the Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Donald R Smith
- the Department of Microbiology and Environmental Toxicology, University of California at Santa Cruz, Santa Cruz, California 95064
| | - Somshuvra Mukhopadhyay
- From the Division of Pharmacology & Toxicology, College of Pharmacy, Institute for Cellular & Molecular Biology, and Institute for Neuroscience and
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10
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Bonnemaison ML, Duffy ME, Mains RE, Vogt S, Eipper BA, Ralle M. Copper, zinc and calcium: imaging and quantification in anterior pituitary secretory granules. Metallomics 2016; 8:1012-22. [PMID: 27426256 DOI: 10.1039/c6mt00079g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The anterior pituitary is specialized for the synthesis, storage and release of peptide hormones. The activation of inactive peptide hormone precursors requires a specific set of proteases and other post-translational processing enzymes. High levels of peptidylglycine α-amidating monooxygenase (PAM), an essential peptide processing enzyme, occur in the anterior pituitary. PAM, which converts glycine-extended peptides into amidated products, requires copper and zinc to support its two catalytic activities and calcium for structure. We used X-ray fluorescence microscopy on rat pituitary sections and inductively coupled plasma mass spectrometry on subcellular fractions prepared from rat anterior pituitary to localize and quantify copper, zinc and calcium. X-ray fluorescence microscopy indicated that the calcium concentration in pituitary tissue was about 2.5 mM, 10-times more than zinc and 50-times more than copper. Although no higher than cytosolic levels, secretory granule levels of copper exceeded PAM levels by a factor of 10. Atp7a, which transports copper into the lumen of the secretory pathway, was enriched in endosomes and Golgi, not in secretory granules. If Atp7a transfers copper directly to PAM, this pH-dependent process is likely to occur in Golgi and endosomes.
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Affiliation(s)
- Mathilde L Bonnemaison
- Department of Molecular Biology and Biophysics, UConn Health, 263 Farmington Avenue, Farmington, CT 06030, USA.
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Petkovic V, Miletta MC, Eblé A, Flück CE, Mullis PE. Alteration of ZnT5-mediated zinc import into the early secretory pathway affects the secretion of growth hormone from rat pituitary cells. Horm Res Paediatr 2015; 82:245-51. [PMID: 25196974 DOI: 10.1159/000365924] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/14/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Aggregation of growth hormone (GH) required for its proper storage in granules is facilitated by zinc (Zn(2+)) transported by specific zinc transporters in and out of the regulated secretory pathway. Slc30a5 (ZnT5) was reported to have the highest gene expression among all zinc transporters in primary mouse pituitary cells while ZnT5-null mice presented with abnormal bone development and impaired growth compared to wild-type counterparts. METHODS In vitro studies performed in GH3 cells, a rat pituitary cell line that endogenously produces rat GH (rGH), included analysis of: cytoplasmic Zn(2+) pool changes after altering rSlc30a5 expression (luciferase assay), rZnT5 association with different compartments of the regulated secretory pathway (confocal microscopy), and the rGH secretion after rSlc30a5 knock-down (Western blot). RESULTS Confocal microscopy demonstrated high co-localization of rZnT5 with ER and Golgi (early secretory pathway) while siRNA-mediated knock-down of rSlc30a5 gene expression led to a significant reduction in rGH secretion. Furthermore, altered expression of rSlc30a5 (knock-down/overexpression) evoked changes in the cytoplasmic Zn(2+) pool indicating its important role in mediating Zn(2+) influx into intracellular compartments of the regulated secretory pathway. CONCLUSION Taken together, these results suggest that ZnT5 might play an important role in regulated GH secretion that is much greater than previously anticipated.
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Affiliation(s)
- Vibor Petkovic
- Division of Pediatric Endocrinology, Diabetology and Metabolism and Department of Clinical Research, University Children's Hospital, Bern, Switzerland
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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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Schweiger M, Steffl M, Amselgruber WM. The zinc transporter ZnT8 (slc30A8) is expressed exclusively in beta cells in porcine islets. Histochem Cell Biol 2013; 140:677-84. [DOI: 10.1007/s00418-013-1137-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2013] [Indexed: 11/28/2022]
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