1
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Silva DB, Trinidad M, Ljungdahl A, Revalde JL, Berguig GY, Wallace W, Patrick CS, Bomba L, Arkin M, Dong S, Estrada K, Hutchinson K, LeBowitz JH, Schlessinger A, Johannesen KM, Møller RS, Giacomini KM, Froelich S, Sanders SJ, Wuster A. Haploinsufficiency underlies the neurodevelopmental consequences of SLC6A1 variants. Am J Hum Genet 2024:S0002-9297(24)00162-9. [PMID: 38781976 DOI: 10.1016/j.ajhg.2024.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024] Open
Abstract
Heterozygous variants in SLC6A1, encoding the GAT-1 GABA transporter, are associated with seizures, developmental delay, and autism. The majority of affected individuals carry missense variants, many of which are recurrent germline de novo mutations, raising the possibility of gain-of-function or dominant-negative effects. To understand the functional consequences, we performed an in vitro GABA uptake assay for 213 unique variants, including 24 control variants. De novo variants consistently resulted in a decrease in GABA uptake, in keeping with haploinsufficiency underlying all neurodevelopmental phenotypes. Where present, ClinVar pathogenicity reports correlated well with GABA uptake data; the functional data can inform future reports for the remaining 72% of unscored variants. Surface localization was assessed for 86 variants; two-thirds of loss-of-function missense variants prevented GAT-1 from being present on the membrane while GAT-1 was on the surface but with reduced activity for the remaining third. Surprisingly, recurrent de novo missense variants showed moderate loss-of-function effects that reduced GABA uptake with no evidence for dominant-negative or gain-of-function effects. Using linear regression across multiple missense severity scores to extrapolate the functional data to all potential SLC6A1 missense variants, we observe an abundance of GAT-1 residues that are sensitive to substitution. The extent of this missense vulnerability accounts for the clinically observed missense enrichment; overlap with hypermutable CpG sites accounts for the recurrent missense variants. Strategies to increase the expression of the wild-type SLC6A1 allele are likely to be beneficial across neurodevelopmental disorders, though the developmental stage and extent of required rescue remain unknown.
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Affiliation(s)
- Dina Buitrago Silva
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Marena Trinidad
- BioMarin Pharmaceutical Inc., Novato, CA, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Alicia Ljungdahl
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA; Institute of Developmental and Regenerative Medicine, Department of Paediatrics, University of Oxford, Oxford OX3 7TY, UK
| | - Jezrael L Revalde
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Cory S Patrick
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | | | - Michelle Arkin
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Shan Dong
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | | | - Keino Hutchinson
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | | | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Katrine M Johannesen
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Rikke S Møller
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark; Department of Epilepsy Genetics and Personalized Medicine, Member of ERN Epicare, Danish Epilepsy Centre, Dianalund, Denmark
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | | | - Stephan J Sanders
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA; Institute of Developmental and Regenerative Medicine, Department of Paediatrics, University of Oxford, Oxford OX3 7TY, UK.
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2
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Sun C, He B, Gao Y, Wang X, Liu X, Sun L. Structural insights into the calcium-coupled zinc export of human ZnT1. SCIENCE ADVANCES 2024; 10:eadk5128. [PMID: 38669333 PMCID: PMC11051671 DOI: 10.1126/sciadv.adk5128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 03/27/2024] [Indexed: 04/28/2024]
Abstract
Cellular zinc (Zn2+) homeostasis is essential to human health and is under tight regulations. Human zinc transporter 1 (hZnT1) is a plasma membrane-localized Zn2+ exporter belonging to the ZnT family, and its functional aberration is associated with multiple diseases. Here, we show that hZnT1 works as a Zn2+/Ca2+ exchanger. We determine the structure of hZnT1 using cryo-electron microscopy (cryo-EM) single particle analysis. hZnT1 adopts a homodimeric structure, and each subunit contains a transmembrane domain consisting of six transmembrane segments, a cytosolic domain, and an extracellular domain. The transmembrane region displays an outward-facing conformation. On the basis of structural and functional analysis, we propose a model for the hZnT1-mediated Zn2+/Ca2+ exchange. Together, these results facilitate our understanding of the biological functions of hZnT1 and provide a basis for further investigations of the ZnT family transporters.
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Affiliation(s)
- Chunqiao Sun
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Bangguo He
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Department of Hematology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - Yongxiang Gao
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Cryo-EM Center, Core Facility Center for Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Xingbing Wang
- Department of Hematology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - Xin Liu
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Linfeng Sun
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
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3
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Zheng Z, Goncearenco A, Berezovsky IN. Back in time to the Gly-rich prototype of the phosphate binding elementary function. Curr Res Struct Biol 2024; 7:100142. [PMID: 38655428 PMCID: PMC11035071 DOI: 10.1016/j.crstbi.2024.100142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 03/31/2024] [Accepted: 04/03/2024] [Indexed: 04/26/2024] Open
Abstract
Binding of nucleotides and their derivatives is one of the most ancient elementary functions dating back to the Origin of Life. We review here the works considering one of the key elements in binding of (di)nucleotide-containing ligands - phosphate binding. We start from a brief discussion of major participants, conditions, and events in prebiotic evolution that resulted in the Origin of Life. Tracing back to the basic functions, including metal and phosphate binding, and, potentially, formation of primitive protein-protein interactions, we focus here on the phosphate binding. Critically assessing works on the structural, functional, and evolutionary aspects of phosphate binding, we perform a simple computational experiment reconstructing its most ancient and generic sequence prototype. The profiles of the phosphate binding signatures have been derived in form of position-specific scoring matrices (PSSMs), their peculiarities depending on the type of the ligands have been analyzed, and evolutionary connections between them have been delineated. Then, the apparent prototype that gave rise to all relevant phosphate-binding signatures had also been reconstructed. We show that two major signatures of the phosphate binding that discriminate between the binding of dinucleotide- and nucleotide-containing ligands are GxGxxG and GxxGxG, respectively. It appears that the signature archetypal for dinucleotide-containing ligands is more generic, and it can frequently bind phosphate groups in nucleotide-containing ligands as well. The reconstructed prototype's key signature GxGGxG underlies the role of glycine residues in providing flexibility and interactions necessary for binding the phosphate groups. The prototype also contains other ancient amino acids, valine, and alanine, showing versatility towards evolutionary design and functional diversification.
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Affiliation(s)
- Zejun Zheng
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, 138671, Singapore
| | | | - Igor N. Berezovsky
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, 138671, Singapore
- Department of Biological Sciences (DBS), National University of Singapore (NUS), 8 Medical Drive, 117579, Singapore
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4
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Fan YG, Wu TY, Zhao LX, Jia RJ, Ren H, Hou WJ, Wang ZY. From zinc homeostasis to disease progression: Unveiling the neurodegenerative puzzle. Pharmacol Res 2024; 199:107039. [PMID: 38123108 DOI: 10.1016/j.phrs.2023.107039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/16/2023] [Accepted: 12/10/2023] [Indexed: 12/23/2023]
Abstract
Zinc is a crucial trace element in the human body, playing a role in various physiological processes such as oxidative stress, neurotransmission, protein synthesis, and DNA repair. The zinc transporters (ZnTs) family members are responsible for exporting intracellular zinc, while Zrt- and Irt-like proteins (ZIPs) are involved in importing extracellular zinc. These processes are essential for maintaining cellular zinc homeostasis. Imbalances in zinc metabolism have been linked to the development of neurodegenerative diseases. Disruptions in zinc levels can impact the survival and activity of neurons, thereby contributing to the progression of neurodegenerative diseases through mechanisms like cell apoptosis regulation, protein phase separation, ferroptosis, oxidative stress, and neuroinflammation. Therefore, conducting a systematic review of the regulatory network of zinc and investigating the relationship between zinc dysmetabolism and neurodegenerative diseases can enhance our understanding of the pathogenesis of these diseases. Additionally, it may offer new insights and approaches for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Yong-Gang Fan
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China.
| | - Ting-Yao Wu
- First Affiliated Hospital of Jinzhou Medical University, Jinzhou 121000, China
| | - Ling-Xiao Zhao
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Rong-Jun Jia
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Hang Ren
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Wen-Jia Hou
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Zhan-You Wang
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China.
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5
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Muto T, Kawase Y, Aiba K, Okuma M, Itsumura N, Luo S, Ogawa N, Tsuji T, Kambe T. Novel
SLC30A2
mutations in the pathogenesis of transient neonatal zinc deficiency. Pediatr Investig 2023; 7:6-12. [PMID: 36967740 PMCID: PMC10030689 DOI: 10.1002/ped4.12366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 01/18/2023] [Indexed: 02/25/2023] Open
Abstract
Importance Transient neonatal zinc deficiency (TNZD) occurs in breastfed infants due to abnormally low breast milk zinc levels. Mutations in the solute carrier family 30 member 2 (SLC30A2) gene, which encodes the zinc transporter ZNT2, cause low zinc concentration in breast milk. Objective This study aimed to provide further insights into TNZD pathophysiology. Methods SLC30A2 sequencing was performed in three unrelated Japanese mothers, whose infants developed TNZD due to low-zinc milk consumption. The effects of the identified mutations were examined using cell-based assays and luciferase reporter analysis. Results Novel SLC30A2 mutations were identified in each mother. One harbored a heterozygous missense mutation in the ZNT2 zinc-binding site, which resulted in defective zinc transport. The other two mothers exhibited multiple heterozygous mutations in the SLC30A2 promoter, the first mutations in the SLC30A2 regulatory region reported to date. Interpretation This report provides new genetic insights into TNZD pathogenesis in breastfed infants.
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Affiliation(s)
- Taichiro Muto
- Department of Pediatrics Aichi Medical University Hospital Nagakute Japan
| | - Yuriko Kawase
- Department of Dermatology Toshiba Central Hospital Tokyo Japan
| | - Kaori Aiba
- Department of Pediatrics Toyohashi Municipal Hospital Toyohashi Japan
| | - Miyuki Okuma
- Department of Pediatrics Toshiba Central Hospital Tokyo Japan
| | - Naoya Itsumura
- Department of Applied Molecular Biology, Division of Integrated Life Science Graduate School of Biostudies Kyoto University Kyoto Japan
| | - Shuangyu Luo
- Department of Applied Molecular Biology, Division of Integrated Life Science Graduate School of Biostudies Kyoto University Kyoto Japan
| | - Namino Ogawa
- Department of Applied Molecular Biology, Division of Integrated Life Science Graduate School of Biostudies Kyoto University Kyoto Japan
| | - Tokuji Tsuji
- Department of Applied Molecular Biology, Division of Integrated Life Science Graduate School of Biostudies Kyoto University Kyoto Japan
| | - Taiho Kambe
- Department of Applied Molecular Biology, Division of Integrated Life Science Graduate School of Biostudies Kyoto University Kyoto Japan
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Willekens J, Runnels LW. Impact of Zinc Transport Mechanisms on Embryonic and Brain Development. Nutrients 2022; 14:nu14122526. [PMID: 35745255 PMCID: PMC9231024 DOI: 10.3390/nu14122526] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/09/2022] [Accepted: 06/09/2022] [Indexed: 12/04/2022] Open
Abstract
The trace element zinc (Zn) binds to over ten percent of proteins in eukaryotic cells. Zn flexible chemistry allows it to regulate the activity of hundreds of enzymes and influence scores of metabolic processes in cells throughout the body. Deficiency of Zn in humans has a profound effect on development and in adults later in life, particularly in the brain, where Zn deficiency is linked to several neurological disorders. In this review, we will summarize the importance of Zn during development through a description of the outcomes of both genetic and early dietary Zn deficiency, focusing on the pathological consequences on the whole body and brain. The epidemiology and the symptomology of Zn deficiency in humans will be described, including the most studied inherited Zn deficiency disease, Acrodermatitis enteropathica. In addition, we will give an overview of the different forms and animal models of Zn deficiency, as well as the 24 Zn transporters, distributed into two families: the ZIPs and the ZnTs, which control the balance of Zn throughout the body. Lastly, we will describe the TRPM7 ion channel, which was recently shown to contribute to intestinal Zn absorption and has its own significant impact on early embryonic development.
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7
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Li X, Chen X, Gao J, Xian J, Li Z, Bi L, Yang M, Yang S, Jin H, Shan H. Loss-of-function Mutations K11E or E271K Lead to Novel Tumor Suppression, Implicate Nucleolar Helicase DDX24 Oncogenicity. Int J Med Sci 2022; 19:596-608. [PMID: 35370459 PMCID: PMC8964322 DOI: 10.7150/ijms.67840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 02/17/2022] [Indexed: 11/16/2022] Open
Abstract
Purpose: Mutations (K11E or E271K) of DEAD-box RNA helicase 24 (DDX24) were related to multi-organ venous lymphatic malformation syndrome (MOVLD). However, the relationship between these mutations and DDX24-function still remains unknown. Understanding whether K11E and E271K cause "loss-of-function" or "gain-of-function" for DDX24 is significant for related diseases. DDX24 was reported to be related to tumors closely, thus this study aims to explore how K11E and E271K affect DDX24-function in tumor proliferation. Methods: Cell lines stably expressing wild-type DDX24, K11E-DDX24, E271K-DDX24, along with vector only based on Chinese hamster ovary cells (CHO) and Balb/c tumor-bearing mice models were constructed. Then immunofluorescence staining, proliferation assay and colony formation assay in vitro and 18F-FDG PET/CT-scan were performed. Finally, the tumor tissues were collected to perform transcriptome sequencing to predict the potential mechanism. Results: Contrasted with CHO-WT-DDX24, CHO-K11E-DDX24 or CHO-E271K-DDX24 showed a decreased number of nucleoli, a slower proliferation rate and a lower colony formation rate significantly. Moreover, mice, inoculated with CHO-K11E-DDX24 or CHO-E271K-DDX24 cells, showed lower tumor formation rate, slower tumor growth rate, better prognosis, reduced standard uptake value and Ki of glucose in subcutaneous tumors. Sequencing indicated CHO-K11E-DDX24 or CHO-E271K-DDX24 caused increasing expression of TNF or chemokines and alteration in immune-related signal pathways. Conclusion: K11E or E271K mutation could lead to "loss-of-function" of DDX24 in cell proliferation and tumor bearing mice, which may be acted by non-specific immune killing to inhibit tumor growth.
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Affiliation(s)
- Xinglin Li
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China.,Department of Ultrasound, The First Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen Second People's Hospital, Shenzhen, Guangdong Province 518000, China
| | - Xiaoyun Chen
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China.,Department of Radiology, Zhongshan Affiliated Hospital, Guangzhou University of Chinese Medicine, Zhongshan, Guangdong Province 528400, China
| | - Jiebing Gao
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China.,Department of Radiology, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Jianzhong Xian
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China.,Department of Ultrasound, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Zhijun Li
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Lei Bi
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Min Yang
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Shuai Yang
- Center of Oncology, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Hongjun Jin
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
| | - Hong Shan
- Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China.,Department of Interventional Medicine, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province 519000, China
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8
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Zinc Signaling in the Mammary Gland: For Better and for Worse. Biomedicines 2021; 9:biomedicines9091204. [PMID: 34572390 PMCID: PMC8469023 DOI: 10.3390/biomedicines9091204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/06/2021] [Accepted: 09/06/2021] [Indexed: 02/07/2023] Open
Abstract
Zinc (Zn2+) plays an essential role in epithelial physiology. Among its many effects, most prominent is its action to accelerate cell proliferation, thereby modulating wound healing. It also mediates affects in the gastrointestinal system, in the testes, and in secretory organs, including the pancreas, salivary, and prostate glands. On the cellular level, Zn2+ is involved in protein folding, DNA, and RNA synthesis, and in the function of numerous enzymes. In the mammary gland, Zn2+ accumulation in maternal milk is essential for supporting infant growth during the neonatal period. Importantly, Zn2+ signaling also has direct roles in controlling mammary gland development or, alternatively, involution. During breast cancer progression, accumulation or redistribution of Zn2+ occurs in the mammary gland, with aberrant Zn2+ signaling observed in the malignant cells. Here, we review the current understanding of the role of in Zn2+ the mammary gland, and the proteins controlling cellular Zn2+ homeostasis and signaling, including Zn2+ transporters and the Gq-coupled Zn2+ sensing receptor, ZnR/GPR39. Significant advances in our understanding of Zn2+ signaling in the normal mammary gland as well as in the context of breast cancer provides new avenues for identification of specific targets for breast cancer therapy.
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9
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Barber-Zucker S, Moran A, Zarivach R. Metal transport mechanism of the cation diffusion facilitator (CDF) protein family - a structural perspective on human CDF (ZnT)-related diseases. RSC Chem Biol 2021; 2:486-498. [PMID: 34458794 PMCID: PMC8341793 DOI: 10.1039/d0cb00181c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/26/2020] [Indexed: 11/21/2022] Open
Abstract
Divalent d-block metal cations (DDMCs) participate in many cellular functions; however, their accumulation in cells can be cytotoxic. The cation diffusion facilitator (CDF) family is a ubiquitous family of transmembrane DDMC exporters that ensures their homeostasis. Severe diseases, such as type II diabetes, Parkinson's and Alzheimer's disease, were linked to dysfunctional human CDF proteins, ZnT-1-10 (SLC30A1-10). Each member of the CDF family reduces the cytosolic concentration of a specific DDMC by transporting it from the cytoplasm to the extracellular environment or into intracellular compartments. This process is usually achieved by utilizing the proton motive force. In addition to their activity as DDMC transporters, CDFs also have other cellular functions such as the regulation of ion channels and enzymatic activity. The combination of structural and biophysical studies of different bacterial and eukaryotic CDF proteins led to significant progress in the understanding of the mutual interaction among CDFs and DDMCs, their involvement in ion binding and selectivity, conformational changes and the consequent transporting mechanisms. Here, we review these studies, provide our mechanistic interpretation of CDF proteins based on the current literature and relate the above to known human CDF-related diseases. Our analysis provides a common structure-function relationship to this important protein family and closes the gap between eukaryote and prokaryote CDFs.
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Affiliation(s)
- Shiran Barber-Zucker
- Department of Life Sciences, the National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev P.O.B. 653 Beer Sheva 8410501 Israel +972-8-6472970 +972-8-6472970 +972-8-6428447 +972-8-6461999
| | - Arie Moran
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev P.O.B. 653 Beer Sheva 8410501 Israel
| | - Raz Zarivach
- Department of Life Sciences, the National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev P.O.B. 653 Beer Sheva 8410501 Israel +972-8-6472970 +972-8-6472970 +972-8-6428447 +972-8-6461999
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10
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Kambe T, Taylor KM, Fu D. Zinc transporters and their functional integration in mammalian cells. J Biol Chem 2021; 296:100320. [PMID: 33485965 PMCID: PMC7949119 DOI: 10.1016/j.jbc.2021.100320] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/15/2021] [Accepted: 01/20/2021] [Indexed: 12/14/2022] Open
Abstract
Zinc is a ubiquitous biological metal in all living organisms. The spatiotemporal zinc dynamics in cells provide crucial cellular signaling opportunities, but also challenges for intracellular zinc homeostasis with broad disease implications. Zinc transporters play a central role in regulating cellular zinc balance and subcellular zinc distributions. The discoveries of two complementary families of mammalian zinc transporters (ZnTs and ZIPs) in the mid-1990s spurred much speculation on their metal selectivity and cellular functions. After two decades of research, we have arrived at a biochemical description of zinc transport. However, in vitro functions are fundamentally different from those in living cells, where mammalian zinc transporters are directed to specific subcellular locations, engaged in dedicated macromolecular machineries, and connected with diverse cellular processes. Hence, the molecular functions of individual zinc transporters are reshaped and deeply integrated in cells to promote the utilization of zinc chemistry to perform enzymatic reactions, tune cellular responsiveness to pathophysiologic signals, and safeguard cellular homeostasis. At present, the underlying mechanisms driving the functional integration of mammalian zinc transporters are largely unknown. This knowledge gap has motivated a shift of the research focus from in vitro studies of purified zinc transporters to in cell studies of mammalian zinc transporters in the context of their subcellular locations and protein interactions. In this review, we will outline how knowledge of zinc transporters has been accumulated from in-test-tube to in-cell studies, highlighting new insights and paradigm shifts in our understanding of the molecular and cellular basis of mammalian zinc transporter functions.
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Affiliation(s)
- Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kathryn M Taylor
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
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11
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Earley BJ, Mendoza AD, Tan CH, Kornfeld K. Zinc homeostasis and signaling in the roundworm C. elegans. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118882. [PMID: 33017595 DOI: 10.1016/j.bbamcr.2020.118882] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/11/2020] [Accepted: 09/25/2020] [Indexed: 12/14/2022]
Abstract
C. elegans is a powerful model for studies of zinc biology. Here we review recent discoveries and emphasize the advantages of this model organism. Methods for manipulating and measuring zinc levels have been developed in or adapted to the worm. The C. elegans genome encodes highly conserved zinc transporters, and their expression and function are beginning to be characterized. Homeostatic mechanisms have evolved to respond to high and low zinc conditions. The pathway for high zinc homeostasis has been recently elucidated based on the discovery of the master regulator of high zinc homeostasis, HIZR-1. A parallel pathway for low zinc homeostasis is beginning to emerge based on the discovery of the Low Zinc Activation promoter element. Zinc has been established to play a role in two cell fate determination events, and accumulating evidence suggests zinc may function as a second messenger signaling molecule during vulval cell development and sperm activation.
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Affiliation(s)
- Brian J Earley
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, United States of America
| | - Adelita D Mendoza
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, United States of America
| | - Chieh-Hsiang Tan
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, United States of America
| | - Kerry Kornfeld
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, United States of America.
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12
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The involvement of zinc transporters in the zinc accumulation in the Pacific oyster Crassostrea gigas. Gene 2020; 750:144759. [DOI: 10.1016/j.gene.2020.144759] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/03/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022]
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13
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Golan Y, Assaraf YG. Genetic and Physiological Factors Affecting Human Milk Production and Composition. Nutrients 2020; 12:E1500. [PMID: 32455695 PMCID: PMC7284811 DOI: 10.3390/nu12051500] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 05/17/2020] [Accepted: 05/19/2020] [Indexed: 02/07/2023] Open
Abstract
Human milk is considered the optimal nutrition for infants as it provides additional attributes other than nutritional support for the infant and contributes to the mother's health as well. Although breastfeeding is the most natural modality to feed infants, nowadays, many mothers complain about breastfeeding difficulties. In addition to environmental factors that may influence lactation outcomes including maternal nutrition status, partner's support, stress, and latching ability of the infant, intrinsic factors such as maternal genetics may also affect the quantitative production and qualitative content of human milk. These genetic factors, which may largely affect the infant's growth and development, as well as the mother's breastfeeding experience, are the subject of the present review. We specifically describe genetic variations that were shown to affect quantitative human milk supply and/or its qualitative content. We further discuss possible implications and methods for diagnosis as well as treatment modalities. Although cases of nutrient-deficient human milk are considered rare, in some ethnic groups, genetic variations that affect human milk content are more abundant, and they should receive greater attention for diagnosis and treatment when necessary. From a future perspective, early genetic diagnosis should be directed to target and treat breastfeeding difficulties in real time.
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Affiliation(s)
| | - Yehuda G. Assaraf
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
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14
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Belfort MB, Ramel SE. NICU Diet, Physical Growth and Nutrient Accretion, and Preterm Infant Brain Development. Neoreviews 2020; 20:e385-e396. [PMID: 31261105 DOI: 10.1542/neo.20-7-e385] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Half of very preterm infants experience neurodevelopmental impairments after NICU discharge. These adverse outcomes result in part from abnormal brain development and injury that occur during the NICU hospitalization. Although many factors influence infant brain development, nutritional determinants are of particular interest because they are highly modifiable within clinical care. Physical growth of preterm infants in the NICU continues to lag behind the reference fetus, suggesting reduced nutrient accretion during a critical period for brain development. Nutrient accretion is driven by intake of specific nutrients such as macro- and micronutrients as well as non-nutritional factors such as systemic inflammation. Most often, anthropometric indicators, such as weight, length, and head circumference, are used as proxies for nutrient accretion. A limitation of weight is that it does not differentiate the healthy growth of specific organs and tissues from excess fat accumulation. Body length provides information about skeletal growth, and linear growth stunting predicts neurodevelopmental impairment. Head circumference is only a crude proxy for brain size. More recently, application of new technologies such as air displacement plethysmography and magnetic resonance imaging has allowed the direct estimation of lean tissue accretion and brain growth in the NICU. These newer techniques can facilitate research to improve our understanding of the links among the NICU diet, inflammation, physical growth, and brain development. These new measures may also be relevant within clinical care to identify infants who may benefit from specific interventions to enhance nutrient accretion and brain development.
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Affiliation(s)
- Mandy Brown Belfort
- Department of Pediatric Newborn Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Sara E Ramel
- Division of Neonatology, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN
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15
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Li Z, Wang J, Yang Y, Wang S. A novel homozygous mutation p.E88K in maternal
SLC30A2
gene as a cause of transient neonatal zinc deficiency. Exp Dermatol 2020; 29:556-561. [PMID: 32278324 DOI: 10.1111/exd.14099] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 02/26/2020] [Accepted: 04/01/2020] [Indexed: 02/05/2023]
Affiliation(s)
- Zhongtao Li
- Department of Dermatovenereology West China Hospital Sichuan University Chengdu China
| | - Jiayue Wang
- Department of Dermatovenereology West China Hospital Sichuan University Chengdu China
| | - Yuan Yang
- Department of Medical Genetics West China Hospital Sichuan University Chengdu China
| | - Sheng Wang
- Department of Dermatovenereology West China Hospital Sichuan University Chengdu China
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16
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Rivera OC, Geddes DT, Barber-Zucker S, Zarivach R, Gagnon A, Soybel DI, Kelleher SL. A common genetic variant in zinc transporter ZnT2 (Thr288Ser) is present in women with low milk volume and alters lysosome function and cell energetics. Am J Physiol Cell Physiol 2020; 318:C1166-C1177. [PMID: 32320289 DOI: 10.1152/ajpcell.00383.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Suboptimal lactation is a common, yet underappreciated cause for early cessation of breastfeeding. Molecular regulation of mammary gland function is critical to the process lactation; however, physiological factors underlying insufficient milk production are poorly understood. The zinc (Zn) transporter ZnT2 is critical for regulation of mammary gland development and maturation during puberty, lactation, and postlactation gland remodeling. Numerous genetic variants in the gene encoding ZnT2 (SLC30A2) are associated with low milk Zn concentration and result in severe Zn deficiency in exclusively breastfed infants. However, the functional impacts of genetic variation in ZnT2 on key mammary epithelial cell functions have not yet been systematically explored at the cellular level. Here we determined a common mutation in SLC30A2/ZnT2 substituting serine for threonine at amino acid 288 (Thr288Ser) was found in 20% of women producing low milk volume (n = 2/10) but was not identified in women producing normal volume. Exploration of cellular consequences in vitro using phosphomimetics showed the serine substitution promoted preferential phosphorylation of ZnT2, driving localization to the lysosome and increasing lysosome biogenesis and acidification. While the substitution did not initiate lysosome-mediated cell death, cellular ATP levels were significantly reduced. Our findings demonstrate the Thr288Ser mutation in SLC30A2/ZnT2 impairs critical functions of mammary epithelial cells and suggest a role for genetic variation in the regulation of milk production and lactation performance.
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Affiliation(s)
- Olivia C Rivera
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania.,Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania
| | - Donna T Geddes
- School of Molecular Sciences, The University of Western Australia, Perth, Australia
| | - Shiran Barber-Zucker
- Department of Life Sciences, The National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, The National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Annie Gagnon
- Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell, Lowell, Massachusetts
| | - David I Soybel
- Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania
| | - Shannon L Kelleher
- Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell, Lowell, Massachusetts
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17
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Abstract
Metals are essential components in all forms of life required for the function of nearly half of all enzymes and are critically involved in virtually all fundamental biological processes. Especially, the transition metals iron (Fe), zinc (Zn), manganese (Mn), nickel (Ni), copper (Cu) and cobalt (Co) are crucial micronutrients known to play vital roles in metabolism as well due to their unique redox properties. Metals carry out three major functions within metalloproteins: to provide structural support, to serve as enzymatic cofactors, and to mediate electron transportation. Metal ions are also involved in the immune system from metal allergies to nutritional immunity. Within the past decade, much attention has been drawn to the roles of metal ions in the immune system, since increasing evidence has mounted to suggest that metals are critically implicated in regulating both the innate immune sensing of and the host defense against invading pathogens. The importance of ions in immunity is also evidenced by the identification of various immunodeficiencies in patients with mutations in ion channels and transporters. In addition, cancer immunotherapy has recently been conclusively demonstrated to be effective and important for future tumor treatment, although only a small percentage of cancer patients respond to immunotherapy because of inadequate immune activation. Importantly, metal ion-activated immunotherapy is becoming an effective and potential way in tumor therapy for better clinical application. Nevertheless, we are still in a primary stage of discovering the diverse immunological functions of ions and mechanistically understanding the roles of these ions in immune regulation. This review summarizes recent advances in the understanding of metal-controlled immunity. Particular emphasis is put on the mechanisms of innate immune stimulation and T cell activation by the essential metal ions like calcium (Ca2+), zinc (Zn2+), manganese (Mn2+), iron (Fe2+/Fe3+), and potassium (K+), followed by a few unessential metals, in order to draw a general diagram of metalloimmunology.
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Affiliation(s)
- Chenguang Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Rui Zhang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Xiaoming Wei
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Mengze Lv
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Zhengfan Jiang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
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18
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Genetic Disorders Associated with Metal Metabolism. Cells 2019; 8:cells8121598. [PMID: 31835360 PMCID: PMC6952812 DOI: 10.3390/cells8121598] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 12/12/2022] Open
Abstract
Genetic disorders associated with metal metabolism form a large group of disorders and mostly result from defects in the proteins/enzymes involved in nutrient metabolism and energy production. These defects can affect different metabolic pathways and cause mild to severe disorders related to metal metabolism. Some disorders have moderate to severe clinical consequences. In severe cases, these elements accumulate in different tissues and organs, particularly the brain. As they are toxic and interfere with normal biological functions, the severity of the disorder increases. However, the human body requires a very small amount of these elements, and a deficiency of or increase in these elements can cause different genetic disorders to occur. Some of the metals discussed in the present review are copper, iron, manganese, zinc, and selenium. These elements may play a key role in the pathology and physiology of the nervous system.
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19
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Lehvy AI, Horev G, Golan Y, Glaser F, Shammai Y, Assaraf YG. Alterations in ZnT1 expression and function lead to impaired intracellular zinc homeostasis in cancer. Cell Death Discov 2019; 5:144. [PMID: 31728210 PMCID: PMC6851190 DOI: 10.1038/s41420-019-0224-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 08/26/2019] [Accepted: 10/01/2019] [Indexed: 02/08/2023] Open
Abstract
Zinc is vital for the structure and function of ~3000 human proteins and hence plays key physiological roles. Consequently, impaired zinc homeostasis is associated with various human diseases including cancer. Intracellular zinc levels are tightly regulated by two families of zinc transporters: ZIPs and ZnTs; ZIPs import zinc into the cytosol from the extracellular milieu, or from the lumen of organelles into the cytoplasm. In contrast, the vast majority of ZnTs compartmentalize zinc within organelles, whereas the ubiquitously expressed ZnT1 is the sole zinc exporter. Herein, we explored the hypothesis that qualitative and quantitative alterations in ZnT1 activity impair cellular zinc homeostasis in cancer. Towards this end, we first used bioinformatics to analyze inactivating mutations in ZIPs and ZNTs, catalogued in the COSMIC and gnomAD databases, representing tumor specimens and healthy population controls, respectively. ZnT1, ZnT10, ZIP8, and ZIP10 showed extremely high rates of loss of function mutations in cancer as compared to healthy controls. Analysis of the putative functional impact of missense mutations in ZnT1-ZnT10 and ZIP1-ZIP14, using homologous protein alignment and structural predictions, revealed that ZnT1 displays a markedly increased frequency of predicted functionally deleterious mutations in malignant tumors, as compared to a healthy population. Furthermore, examination of ZnT1 expression in 30 cancer types in the TCGA database revealed five tumor types with significant ZnT1 overexpression, which predicted dismal prognosis for cancer patient survival. Novel functional zinc transport assays, which allowed for the indirect measurement of cytosolic zinc levels, established that wild type ZnT1 overexpression results in low intracellular zinc levels. In contrast, overexpression of predicted deleterious ZnT1 missense mutations did not reduce intracellular zinc levels, validating eight missense mutations as loss of function (LoF) mutations. Thus, alterations in ZnT1 expression and LoF mutations in ZnT1 provide a molecular mechanism for impaired zinc homeostasis in cancer formation and/or progression.
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Affiliation(s)
- Adrian Israel Lehvy
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Guy Horev
- 2Bioinformatics Knowledge Unit, The Lorry, I. Lokey Interdisciplinary Center for Life, Sciences and Engineering, Technion-Israel, Institute of Technology, Haifa, Israel
| | - Yarden Golan
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Fabian Glaser
- 2Bioinformatics Knowledge Unit, The Lorry, I. Lokey Interdisciplinary Center for Life, Sciences and Engineering, Technion-Israel, Institute of Technology, Haifa, Israel
| | - Yael Shammai
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yehuda Gérard Assaraf
- 1The Fred Wyszkowski Cancer Research, Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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20
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Milk-derived miRNA profiles elucidate molecular pathways that underlie breast dysfunction in women with common genetic variants in SLC30A2. Sci Rep 2019; 9:12686. [PMID: 31481661 PMCID: PMC6722070 DOI: 10.1038/s41598-019-48987-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/15/2019] [Indexed: 12/19/2022] Open
Abstract
Studies in humans and pre-clinical animal models show milk-derived miRNAs reflect mammary gland function during lactation. The zinc transporter SLC30A2/ZnT2 plays a critical role in mammary gland function; ZnT2-null mice have profound defects in mammary epithelial cell (MEC) polarity and secretion, resulting in sub-optimal lactation. Non-synonymous genetic variation in SLC30A2 is common in humans, and several common ZnT2 variants are associated with changes in milk components that suggest breast dysfunction in women. To identify novel mechanisms through which dysfunction might occur, milk-derived miRNA profiles were characterized in women harboring three common genetic variants in SLC30A2 (D103E, T288S, and Exon 7). Expression of ten miRNAs differed between genotypes, and contributed to distinct spatial separation. Studies in breast milk and cultured MECs confirmed expression of ZnT2 variants alters abundance of protein levels of several predicted mRNA targets critical for breast function (PRLR, VAMP7, and SOX4). Moreover, bioinformatic analysis identified two novel gene networks that may underlie normal MEC function. Thus, we propose that genetic variation in genes critical for normal breast function such as SLC30A2 has important implications for lactation performance in women, and that milk-derived miRNAs can be used to identify novel mechanisms and for diagnostic potential.
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21
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Gordon SJV, Fenker DE, Vest KE, Padilla-Benavides T. Manganese influx and expression of ZIP8 is essential in primary myoblasts and contributes to activation of SOD2. Metallomics 2019; 11:1140-1153. [PMID: 31086870 PMCID: PMC6584035 DOI: 10.1039/c8mt00348c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Trace elements such as copper (Cu), zinc (Zn), iron (Fe), and manganese (Mn) function as enzyme cofactors and second messengers in cell signaling. Trace elements are emerging as key regulators of differentiation and development of mammalian tissues including blood, brain, and skeletal muscle. We previously reported an influx of Cu and dynamic expression of metal transporters during differentiation of skeletal muscle cells. Here, we demonstrate that during differentiation of skeletal myoblasts an increase of Mn, Fe and Zn also occurs. Interestingly the Mn increase is concomitant with increased Mn-dependent SOD2 levels. To better understand the Mn import pathway in skeletal muscle cells, we probed the functional relevance of the closely related proteins ZIP8 and ZIP14, which are implicated in Zn, Mn, and Fe transport. Partial depletion of ZIP8 severely impaired growth of myoblasts and led to cell death under differentiation conditions, indicating that ZIP8-mediated metal transport is essential in skeletal muscle cells. Moreover, knockdown of Zip8 impaired activity of the Mn-dependent SOD2. Growth defects were partially rescued only by Mn supplementation to the medium, suggesting additional functions for ZIP8 in the skeletal muscle lineage. Restoring wild type Zip8 into the knockdown cells rescued the proliferation and differentiation phenotypes. On the other hand, knockdown of Zip14, had only a mild effect on myotube size, consistent with a role for ZIP14 in muscle hypertrophy. Simultaneous knockdown of both Zip8 and Zip14 further impaired differentiation and led cell death. This is the first report on the functional relevance of two members of the ZIP family of metal transporters in the skeletal muscle lineage, and further supports the paradigm that trace metal transporters are important modulators of mammalian tissue development.
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Affiliation(s)
- Shellaina J. V. Gordon
- Department of Biochemistry and Molecular Pharmacology,
University of Massachusetts Medical School, 394 Plantation St., Worcester, MA,
01605, USA
| | - Daniel E. Fenker
- Department of Molecular Genetics, Biochemistry &
Microbiology, University of Cincinnati School of Medicine, 231 Albert Sabin Way,
Cincinnati, OH, 45267, USA
| | - Katherine E. Vest
- Department of Molecular Genetics, Biochemistry &
Microbiology, University of Cincinnati School of Medicine, 231 Albert Sabin Way,
Cincinnati, OH, 45267, USA
| | - Teresita Padilla-Benavides
- Department of Biochemistry and Molecular Pharmacology,
University of Massachusetts Medical School, 394 Plantation St., Worcester, MA,
01605, USA
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22
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Golan Y, Alhadeff R, Warshel A, Assaraf YG. ZnT2 is an electroneutral proton-coupled vesicular antiporter displaying an apparent stoichiometry of two protons per zinc ion. PLoS Comput Biol 2019; 15:e1006882. [PMID: 30893306 PMCID: PMC6443192 DOI: 10.1371/journal.pcbi.1006882] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 04/01/2019] [Accepted: 02/18/2019] [Indexed: 01/29/2023] Open
Abstract
Zinc is a vital trace element crucial for the proper function of some 3,000 cellular proteins. Specifically, zinc is essential for key physiological processes including nucleic acid metabolism, regulation of gene expression, signal transduction, cell division, immune- and nervous system functions, wound healing, and apoptosis. Consequently, impairment of zinc homeostasis disrupts key cellular functions resulting in various human pathologies. Mammalian zinc transport proceeds via two transporter families ZnT and ZIP. However, the detailed mechanism of action of ZnT2, which is responsible for vesicular zinc accumulation and zinc secretion into breast milk during lactation, is currently unknown. Moreover, although the putative coupling of zinc transport to the proton gradient in acidic vesicles has been suggested, it has not been conclusively established. Herein we modeled the mechanism of action of ZnT2 and demonstrated both computationally and experimentally, using functional zinc transport assays, that ZnT2 is indeed a proton-coupled zinc antiporter. Bafilomycin A1, a specific inhibitor of vacuolar-type proton ATPase (V-ATPase) which alkalizes acidic vesicles, abolished ZnT2-dependent zinc transport into intracellular vesicles. Moreover, using LysoTracker Red and Lyso-pHluorin, we further showed that upon transient ZnT2 overexpression in intracellular vesicles and addition of exogenous zinc, the vesicular pH underwent alkalization, presumably due to a proton-zinc antiport; this phenomenon was reversed in the presence of TPEN, a specific zinc chelator. Finally, based on computational energy calculations, we propose that ZnT2 functions as an antiporter with a stoichiometry of 2H+/Zn2+ ion. Hence, ZnT2 is a proton motive force-driven, electroneutral vesicular zinc exchanger, concentrating zinc in acidic vesicles on the expense of proton extrusion to the cytoplasm. Herein we explored the mechanism of action of the human ZnT2 zinc transporter. ZnT2 is essential for zinc accumulation in breast milk and is therefore of paramount medical significance. Expanding on our previous study, we herein present energy calculations suggesting that ZnT2 functions as a proton/zinc antiporter. Our calculations consist of electrostatic and pKa calculations as well as zinc binding free-energy curves. Upon integration of our calculation results, we conclude that ZnT2 functions as an antiporter with a 2H+/Zn2+ stoichiometry, construct a Monte Carlo model to test this mode of ZnT2 transport activity, and validate our computational results experimentally using live human breast epithelial cells. These functional experiments reveal that ZnT2 cannot function in the absence of protons suggesting that it operates as a substrate-induced alternating-access transporter, displaying an apparent 2H+/Zn2+ stoichiometry.
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Affiliation(s)
- Yarden Golan
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Raphael Alhadeff
- Department of Chemistry, University of Southern California, Los Angeles, California
| | - Arieh Warshel
- Department of Chemistry, University of Southern California, Los Angeles, California
| | - Yehuda G. Assaraf
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
- * E-mail:
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23
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Golan Y, Lehvy A, Horev G, Assaraf YG. High proportion of transient neonatal zinc deficiency causing alleles in the general population. J Cell Mol Med 2018; 23:828-840. [PMID: 30450693 PMCID: PMC6349188 DOI: 10.1111/jcmm.13982] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 01/01/2023] Open
Abstract
Loss of function (LoF) mutations in the zinc transporter SLC30A2/ZnT2 result in impaired zinc secretion into breast milk consequently causing transient neonatal zinc deficiency (TNZD) in exclusively breastfed infants. However, the frequency of TNZD causing alleles in the general population is yet unknown. Herein, we investigated 115 missense SLC30A2/ZnT2 mutations from the ExAC database, equally distributed in the entire coding region, harboured in 668 alleles in 60 706 healthy individuals of diverse ethnicity. To estimate the frequency of LoF SLC30A2/ZnT2 mutations in the general population, we used bioinformatics tools to predict the potential impact of these mutations on ZnT2 functionality, and corroborated these predictions by a zinc transport assay in human MCF-7 cells. We found 14 missense mutations that were markedly deleterious to zinc transport. Together with two conspicuous LoF mutations in the ExAC database, 26 SLC30A2/ZnT2 alleles harboured deleterious mutations, suggesting that at least 1 in 2334 newborn infants are at risk to develop TNZD. This high frequency of TNZD mutations combined with the World Health Organization-promoted increase in the rate of exclusive breastfeeding highlights the importance of genetic screening for inactivating SLC30A2/ZnT2 mutations in the general population for the early diagnosis and prevention of TNZD.
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Affiliation(s)
- Yarden Golan
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Adrian Lehvy
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Guy Horev
- Bioinformatics Knowledge Unit, The Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yehuda G Assaraf
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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24
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Golan Y, Alhadeff R, Glaser F, Ganoth A, Warshel A, Assaraf YG. Demonstrating aspects of multiscale modeling by studying the permeation pathway of the human ZnT2 zinc transporter. PLoS Comput Biol 2018; 14:e1006503. [PMID: 30388104 PMCID: PMC6241132 DOI: 10.1371/journal.pcbi.1006503] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 11/14/2018] [Accepted: 09/11/2018] [Indexed: 11/18/2022] Open
Abstract
Multiscale modeling provides a very powerful means of studying complex biological systems. An important component of this strategy involves coarse-grained (CG) simplifications of regions of the system, which allow effective exploration of complex systems. Here we studied aspects of CG modeling of the human zinc transporter ZnT2. Zinc is an essential trace element with 10% of the proteins in the human proteome capable of zinc binding. Thus, zinc deficiency or impairment of zinc homeostasis disrupt key cellular functions. Mammalian zinc transport proceeds via two transporter families: ZnT and ZIP; however, little is known about the zinc permeation pathway through these transporters. As a step towards this end, we herein undertook comprehensive computational analyses employing multiscale techniques, focusing on the human zinc transporter ZnT2 and its bacterial homologue, YiiP. Energy calculations revealed a favorable pathway for zinc translocation via alternating access. We then identified key residues presumably involved in the passage of zinc ions through ZnT2 and YiiP, and functionally validated their role in zinc transport using site-directed mutagenesis of ZnT2 residues. Finally, we use a CG Monte Carlo simulation approach to sample the transition between the inward-facing and the outward-facing states. We present our structural models of the inward- and outward-facing conformations of ZnT2 as a blueprint prototype of the transporter conformations, including the putative permeation pathway and participating residues. The insights gained from this study may facilitate the delineation of the pathways of other zinc transporters, laying the foundations for the molecular basis underlying ion permeation. This may possibly facilitate the development of therapeutic interventions in pathological states associated with zinc deficiency and other disorders based on loss-of-function mutations in solute carriers.
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Affiliation(s)
- Yarden Golan
- The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Raphael Alhadeff
- Department of Chemistry, University of Southern California, Los Angeles, CA, United States of America
| | - Fabian Glaser
- Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Assaf Ganoth
- The Interdisciplinary Center (IDC), Herzliya, Israel
| | - Arieh Warshel
- Department of Chemistry, University of Southern California, Los Angeles, CA, United States of America
- * E-mail: (AW); (YGA)
| | - Yehuda G. Assaraf
- The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa, Israel
- * E-mail: (AW); (YGA)
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25
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Coverdale JPC, Khazaipoul S, Arya S, Stewart AJ, Blindauer CA. Crosstalk between zinc and free fatty acids in plasma. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:532-542. [PMID: 30266430 PMCID: PMC6372834 DOI: 10.1016/j.bbalip.2018.09.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/23/2018] [Accepted: 09/23/2018] [Indexed: 12/13/2022]
Abstract
In mammalian blood plasma, serum albumin acts as a transport protein for free fatty acids, other lipids and hydrophobic molecules including neurodegenerative peptides, and essential metal ions such as zinc to allow their systemic distribution. Importantly, binding of these chemically extremely diverse entities is not independent, but linked allosterically. One particularly intriguing allosteric link exists between free fatty acid and zinc binding. Albumin thus mediates crosstalk between energy status/metabolism and organismal zinc handling. In recognition of the fact that even small changes in extracellular zinc concentration and speciation modulate the function of many cell types, the albumin-mediated impact of free fatty acid concentration on zinc distribution may be significant for both normal physiological processes including energy metabolism, insulin activity, heparin neutralisation, blood coagulation, and zinc signalling, and a range of disease states, including metabolic syndrome, cardiovascular disease, myocardial ischemia, diabetes, and thrombosis. Serum albumin binds and transports both free fatty acids and Zn2+ ions Elevated plasma free fatty acids impair Zn2+ binding by albumin through an allosteric mechanism The resulting changes in plasma zinc speciation are thought to impact blood coagulation and may promote thrombosis Increased free Zn2+ may lead to enhanced zinc export from plasma and dysregulation of zinc homeostasis in multiple tissues
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Affiliation(s)
| | | | - Swati Arya
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
| | - Alan J Stewart
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
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26
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Evaluation of the roles of the cytosolic N-terminus and His-rich loop of ZNT proteins using ZNT2 and ZNT3 chimeric mutants. Sci Rep 2018; 8:14084. [PMID: 30237557 PMCID: PMC6147782 DOI: 10.1038/s41598-018-32372-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 09/07/2018] [Indexed: 12/01/2022] Open
Abstract
The physiological roles of Zn transporter (ZNT) proteins are being increasingly recognized, and three dimensional structures of ZNT bacterial homologs have facilitated our understanding of their biochemical characteristics at the molecular level. However, the biological role of the unique structural features of vertebrate ZNTs, which are absent in their bacterial homologues, is not completely understood. These ZNT sequences include a cytosolic His-rich loop between transmembrane helices IV and V and the cytosolic N-terminus. This study investigated the contribution of these features to zinc transport by ZNT proteins. The importance of the His residues in the cytosolic His-rich loop was investigated using ZNT2 Ala substitution and deletion mutants. The presence of His residues was not essential for zinc transport, even though they possibly participate in modulation of zinc transport activity. Furthermore, we determined the role of the N-terminus by characterizing ZNT2 and ZNT3 domain-swapped and deletion mutants. Unexpectedly, the N-terminus was also not essential for zinc transport by ZNT2 and the domain-swapped ZNT2 mutant, in which the cytosolic His-rich loop was substituted with that of ZNT3. These results provide molecular insights into understanding the roles of the cytosolic parts of ZNT2, ZNT3, and probably other members of their subgroup.
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27
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Paskavitz AL, Quintana J, Cangussu D, Tavera-Montañez C, Xiao Y, Ortiz-Miranda S, Navea JG, Padilla-Benavides T. Differential expression of zinc transporters accompanies the differentiation of C2C12 myoblasts. J Trace Elem Med Biol 2018; 49:27-34. [PMID: 29895369 PMCID: PMC6082398 DOI: 10.1016/j.jtemb.2018.04.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/16/2018] [Accepted: 04/20/2018] [Indexed: 12/11/2022]
Abstract
Zinc transporters facilitate metal mobilization and compartmentalization, playing a key role in cellular development. Little is known about the mechanisms and pathways of Zn movement between Zn transporters and metalloproteins during myoblast differentiation. We analyzed the differential expression of ZIP and ZnT transporters during C2C12 myoblast differentiation. Zn transporters account for a transient decrease of intracellular Zn upon myogenesis induction followed by a gradual increase of Zn in myotubes. Considering the subcellular localization and function of each of the Zn transporters, our findings indicate that a fine regulation is necessary to maintain correct metal concentrations in the cytosol and subcellular compartments to avoid toxicity, maintain homeostasis, and for loading metalloproteins needed during myogenesis. This study advances our basic understanding of the complex Zn transport network during muscle differentiation.
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Affiliation(s)
- Amanda L Paskavitz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA; Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Julia Quintana
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, 01609, USA
| | - Daniella Cangussu
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA
| | - Cristina Tavera-Montañez
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA; Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, 01609, USA
| | - Yao Xiao
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Sonia Ortiz-Miranda
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA
| | - Juan G Navea
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Teresita Padilla-Benavides
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA.
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28
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Golan Y, Kambe T, Assaraf YG. The role of the zinc transporter SLC30A2/ZnT2 in transient neonatal zinc deficiency. Metallomics 2018; 9:1352-1366. [PMID: 28665435 DOI: 10.1039/c7mt00162b] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Breast milk is the optimal nutrient mix for infants until the age of 6 months. However, in some cases, due to genetic alterations as well as nutrient deficiencies in nursing mothers, infants may suffer from inadequate levels of micronutrients upon exclusive breastfeeding. In this respect, transient neonatal zinc deficiency (TNZD) is caused by loss-of-function mutations in the zinc transporter SLC30A2/ZnT2 gene, resulting in poor secretion of zinc into the breast milk. Consequently, infants exclusively breastfed with zinc-deficient breast milk develop severe zinc deficiency. The main initial symptoms of zinc deficiency are dermatitis, diarrhea, alopecia, and loss of appetite. Importantly, zinc supplementation of these zinc-deficient infants effectively and rapidly resolves these TNZD symptoms. In the current review, we present the major steps towards the identification of the molecular mechanisms underlying TNZD and propose novel approaches that could be implemented in order to achieve an early diagnosis of TNZD towards the prevention of TNZD morbidity. We also discuss the importance of assessing the prevalence of TNZD in the general population, while taking into consideration its autosomal dominant inheritance that was recently established, also supported by a large number of SLC30A2/ZnT2 variants recently identified in American lactating mothers. These findings indicating that TNZD is more frequent than initially thought, along with the increasing number of TNZD cases that were recently reported worldwide, prompted us here to highlight the importance of early diagnosis of SLC30A2/ZnT2 variants in order to supplement zinc-deficient infants in real-time, thus preventing TNZD morbidity and enhancing newborn health. This early genetic diagnosis of zinc deficiency could possibly prove to be a useful platform for the identification of other micronutrient deficiencies, which could be readily resolved by proper real-time supplementation of the infant's diet.
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Affiliation(s)
- Yarden Golan
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
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29
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Abstract
The skin is the third most zinc (Zn)-abundant tissue in the body. The skin consists of the epidermis, dermis, and subcutaneous tissue, and each fraction is composed of various types of cells. Firstly, we review the physiological functions of Zn and Zn transporters in these cells. Several human disorders accompanied with skin manifestations are caused by mutations or dysregulation in Zn transporters; acrodermatitis enteropathica (Zrt-, Irt-like protein (ZIP)4 in the intestinal epithelium and possibly epidermal basal keratinocytes), the spondylocheiro dysplastic form of Ehlers-Danlos syndrome (ZIP13 in the dermal fibroblasts), transient neonatal Zn deficiency (Zn transporter (ZnT)2 in the secretory vesicles of mammary glands), and epidermodysplasia verruciformis (ZnT1 in the epidermal keratinocytes). Additionally, acquired Zn deficiency is deeply involved in the development of some diseases related to nutritional deficiencies (acquired acrodermatitis enteropathica, necrolytic migratory erythema, pellagra, and biotin deficiency), alopecia, and delayed wound healing. Therefore, it is important to associate the existence of mutations or dysregulation in Zn transporters and Zn deficiency with skin manifestations.
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30
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Abstract
Trace elements are chemical elements needed in minute amounts for normal physiology. Some of the physiologically relevant trace elements include iodine, copper, iron, manganese, zinc, selenium, cobalt and molybdenum. Of these, some are metals, and in particular, transition metals. The different electron shells of an atom carry different energy levels, with those closest to the nucleus being lowest in energy. The number of electrons in the outermost shell determines the reactivity of such an atom. The electron shells are divided in sub-shells, and in particular the third shell has s, p and d sub-shells. Transition metals are strictly defined as elements whose atom has an incomplete d sub-shell. This incomplete d sub-shell makes them prone to chemical reactions, particularly redox reactions. Transition metals of biologic importance include copper, iron, manganese, cobalt and molybdenum. Zinc is not a transition metal, since it has a complete d sub-shell. Selenium, on the other hand, is strictly speaking a nonmetal, although given its chemical properties between those of metals and nonmetals, it is sometimes considered a metalloid. In this review, we summarize the current knowledge on the inborn errors of metal and metalloid metabolism.
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Affiliation(s)
- Carlos R. Ferreira
- Division of Genetics and Metabolism, Children’s National Health System, Washington, DC, USA
- Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Washington, DC, USA
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, USA
| | - William A. Gahl
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, USA
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31
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Kambe T, Matsunaga M, Takeda TA. Understanding the Contribution of Zinc Transporters in the Function of the Early Secretory Pathway. Int J Mol Sci 2017; 18:ijms18102179. [PMID: 29048339 PMCID: PMC5666860 DOI: 10.3390/ijms18102179] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/12/2017] [Accepted: 10/15/2017] [Indexed: 01/07/2023] Open
Abstract
More than one-third of newly synthesized proteins are targeted to the early secretory pathway, which is comprised of the endoplasmic reticulum (ER), Golgi apparatus, and other intermediate compartments. The early secretory pathway plays a key role in controlling the folding, assembly, maturation, modification, trafficking, and degradation of such proteins. A considerable proportion of the secretome requires zinc as an essential factor for its structural and catalytic functions, and recent findings reveal that zinc plays a pivotal role in the function of the early secretory pathway. Hence, a disruption of zinc homeostasis and metabolism involving the early secretory pathway will lead to pathway dysregulation, resulting in various defects, including an exacerbation of homeostatic ER stress. The accumulated evidence indicates that specific members of the family of Zn transporters (ZNTs) and Zrt- and Irt-like proteins (ZIPs), which operate in the early secretory pathway, play indispensable roles in maintaining zinc homeostasis by regulating the influx and efflux of zinc. In this review, the biological functions of these transporters are discussed, focusing on recent aspects of their roles. In particular, we discuss in depth how specific ZNT transporters are employed in the activation of zinc-requiring ectoenzymes. The means by which early secretory pathway functions are controlled by zinc, mediated by specific ZNT and ZIP transporters, are also subjects of this review.
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Affiliation(s)
- Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
| | - Mayu Matsunaga
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
| | - Taka-Aki Takeda
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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32
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Abstract
Pediatric skin diseases are a common presenting complaint to emergency medicine physicians but often pose a significant diagnostic challenge. Skin eruptions that are unusually severe for the diagnosis in question, lasting beyond the typical time of resolution, or not responding to conventional therapy should raise concern of a misdiagnosis. We present the case of a severe rash not responding to conventional atopic dermatitis therapy that led to a diagnosis of transient neonatal zinc deficiency. Clinicians caring for children should be aware of zinc deficiency and its corresponding clinical presentation, because it is readily treatable and may lead to the avoidance of unnecessary treatments and prevention of serious complications.
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33
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Doneray H, Olcaysu E, Yildirim A, Ozden A. The effect of the zinc concentration in breast milk on neonatal weight gain. J Trace Elem Med Biol 2017; 41:32-35. [PMID: 28347460 DOI: 10.1016/j.jtemb.2017.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 01/18/2017] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
The change in breast milk zinc (Zn) concentration in a feeding period during lactation may affect neonatal weight gain. The aim of this study was to determine how to change the Zn concentrations in breast milk during a feeding period in early and late lactation periods and identify the relationship between the differences in the Zn levels in breast milk during lactation and neonatal weight gain. Breast milk was collected in the early and late lactation periods with samples being obtained before (foremilk) and after (hindmilk) a feeding period. Then, we determined the Zn concentrations in the breast milk and measured the weight of the infants before and after the same feeding period. The study was composed of 37 newborns and their mothers. During the feeding period, the Zn concentrations in both the transitional and mature milk decreased significantly. During the lactation period, the Zn levels were markedly lower in only the hindmilk. The body weights of the infants both before and after feeding in the early lactation period were negatively correlated with the delta Zn concentration in the same period, but the delta body weights in the early lactation period were positively correlated with the Zn levels in the hindmilk in the same period. In addition, body weights before feeding in the late lactation period were also positively correlated with Zn levels in hindmilk in the early lactation period. This study suggests that the Zn concentrations in both the transitional and mature milk decreased, which suggests that changes in the Zn content of breast milk during lactation might play a role in the weight gain of healthy neonates.
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Affiliation(s)
- Hakan Doneray
- Department of Pediatrics, Ataturk University Faculty of Medicine, 25240, Erzurum, Turkey.
| | - Elif Olcaysu
- Department of Pediatrics, Ataturk University Faculty of Medicine, 25240, Erzurum, Turkey
| | - Abdulkadir Yildirim
- Department of Biochemistry, Ataturk University Faculty of Medicine, 25240, Erzurum, Turkey
| | - Ayse Ozden
- Department of Pediatrics, Ataturk University Faculty of Medicine, 25240, Erzurum, Turkey
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34
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Liew HM, Tan CW, Ho CKM, Chee JN, Koh MJA. Transient Neonatal Zinc Deficiency Caused by a Novel Mutation in the SLC30A2 Gene. Pediatr Dermatol 2017; 34:e104-e105. [PMID: 28111782 DOI: 10.1111/pde.13065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This is a case report of a 4-month-old full-term, fully breastfed boy who presented with a persistent periorificial and groin rash associated with poor weight gain and irritability. His serum zinc level was low. The mother's breast milk zinc level was found to be low despite her serum zinc levels being normal, confirming the diagnosis of transient neonatal zinc deficiency. Mutational analysis revealed a novel mutation in the mother's SLC30A2 gene, which encodes a zinc transporter expressed in mammary gland epithelial cells.
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Affiliation(s)
- Hui M Liew
- Dermatology Service, KK Women's and Children's Hospital, Singapore City, Singapore
| | - Colin W Tan
- Dermatology Service, KK Women's and Children's Hospital, Singapore City, Singapore
| | - Clement K M Ho
- Department of Pathology and Laboratory Medicine, KK Women's and Children's Hospital, Singapore City, Singapore
| | - Jade N Chee
- Dermatology Service, KK Women's and Children's Hospital, Singapore City, Singapore
| | - Mark J A Koh
- Dermatology Service, KK Women's and Children's Hospital, Singapore City, Singapore
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35
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Blume-Peytavi U, Tan J, Tennstedt D, Boralevi F, Fabbrocini G, Torrelo A, Soares-Oliveira R, Haftek M, Rossi AB, Thouvenin MD, Mangold J, Galliano MF, Hernandez-Pigeon H, Aries MF, Rouvrais C, Bessou-Touya S, Duplan H, Castex-Rizzi N, Mengeaud V, Ferret PJ, Clouet E, Saint Aroman M, Carrasco C, Coutanceau C, Guiraud B, Boyal S, Herman A, Delga H, Biniek K, Dauskardt R. Fragility of epidermis in newborns, children and adolescents. J Eur Acad Dermatol Venereol 2016; 30 Suppl 4:3-56. [PMID: 27062556 DOI: 10.1111/jdv.13636] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/10/2016] [Accepted: 02/17/2016] [Indexed: 12/18/2022]
Abstract
Within their first days of life, newborns' skin undergoes various adaptation processes needed to accommodate the transition from the wet uterine environment to the dry atmosphere. The skin of newborns and infants is considered as a physiological fragile skin, a skin with lower resistance to aggressions. Fragile skin is divided into four categories up to its origin: physiological fragile skin (age, location), pathological fragile skin (acute and chronic), circumstantial fragile skin (due to environmental extrinsic factors or intrinsic factors such as stress) and iatrogenic fragile skin. Extensive research of the past 10 years have proven evidence that at birth albeit showing a nearly perfect appearance, newborn skin is structurally and functionally immature compared to adult skin undergoing a physiological maturation process after birth at least throughout the first year of life. This article is an overview of all known data about fragility of epidermis in 'fragile populations': newborns, children and adolescents. It includes the recent pathological, pathophysiological and clinical data about fragility of epidermis in various dermatological diseases, such as atopic dermatitis, acne, rosacea, contact dermatitis, irritative dermatitis and focus on UV protection.
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Affiliation(s)
- U Blume-Peytavi
- Department of Dermatology and Allergy, Clinical Research Center for Hair and Skin Science, Charité-Universitätsmedizin, Berlin, Germany
| | - J Tan
- Department of Medicine, Faculty of Medicine, Schulich School of Medicine and Dentistry, Western University, Windsor campus, Windsor, ON, Canada.,Windsor Clinical Research Inc., Windsor campus, Windsor, ON, Canada
| | - D Tennstedt
- Department of Dermatology, Saint-Luc University Clinics, Brussels, Belgium
| | - F Boralevi
- Pediatric Dermatology, Pellegrin Hospital, Bordeaux, France
| | - G Fabbrocini
- Department of Dermatology, University Hospital of Naples, Naples, Italy
| | - A Torrelo
- Pediatric Dermatology, Hospital del Niño Jesús, Madrid, Spain
| | | | - M Haftek
- University Lyon 1, Lyon, France.,University Lyon 1, EA4169, "Fundamental, clinical and therapeutic aspects of the skin barrier function", Lyon, France
| | - A B Rossi
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Department of Dermatology, Toulouse University hospital, France
| | - M D Thouvenin
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France
| | - J Mangold
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France
| | - M F Galliano
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - H Hernandez-Pigeon
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - M F Aries
- Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - C Rouvrais
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France
| | - S Bessou-Touya
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France.,Medical Department, Pierre Fabre Research and Laboratoires Dermatologiques A-Derma, Lavaur, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - H Duplan
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - N Castex-Rizzi
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - V Mengeaud
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France
| | - P J Ferret
- Pierre Fabre Dermo-Cosmétique Research & Development, Toxicology Division, Vigoulet-Auzil, France.,Pierre Fabre Dermo-Cosmétique Research & Developement Center, Toxicology division, Vigoulet, France
| | - E Clouet
- Pierre Fabre Dermo-Cosmétique Research & Development, Toxicology Division, Vigoulet-Auzil, France.,Pierre Fabre Dermo-Cosmétique Research & Developement Center, Toxicology division, Vigoulet, France
| | | | - C Carrasco
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique Research and Development Center, Pharmacology Division, Toulouse, France.,Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - C Coutanceau
- Medical Department, Pierre Fabre Research and Laboratoires Dermatologiques A-Derma, Lavaur, France
| | - B Guiraud
- Pierre Fabre Dermo-Cosmétique Research & Development, Clinical Division, Toulouse, France
| | - S Boyal
- Windsor Clinical Research Inc., Windsor campus, Windsor, ON, Canada
| | - A Herman
- Department of Dermatology, Saint-Luc University Clinics, Brussels, Belgium
| | - H Delga
- Pierre Fabre Dermo-Cosmétique, Pierre Fabre Research and Development Center, Pharmacology Division, Toulouse, France
| | - K Biniek
- Department of Materials Science and Engineering, Stanford University hospital, Stanford, CA, USA
| | - R Dauskardt
- Department of Materials Science and Engineering, Stanford University hospital, Stanford, CA, USA
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36
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Berezovsky IN, Guarnera E, Zheng Z, Eisenhaber B, Eisenhaber F. Protein function machinery: from basic structural units to modulation of activity. Curr Opin Struct Biol 2016; 42:67-74. [PMID: 27865209 DOI: 10.1016/j.sbi.2016.10.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/26/2016] [Accepted: 10/31/2016] [Indexed: 11/29/2022]
Abstract
Contemporary protein structure is a result of the trade off between the laws of physics and the evolutionary selection. The polymer nature of proteins played a decisive role in establishing the basic structural and functional units of soluble proteins. We discuss how these elementary building blocks work in the hierarchy of protein domain structure, co-translational folding, as well as in enzymatic activity and molecular interactions. Next, we consider modulators of the protein function, such as intermolecular interactions, disorder-to-order transitions, and allosteric signaling, acting via interference with the protein's structural dynamics. We also discuss the post-translational modifications, which is a complementary intricate mechanism evolved for regulation of protein functions and interactions. In conclusion, we assess an anticipated contribution of discussed topics to the future advancements in the field.
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Affiliation(s)
- Igor N Berezovsky
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, Singapore 138671, Singapore; Department of Biological Sciences (DBS), National University of Singapore (NUS), 8 Medical Drive, Singapore 117579, Singapore.
| | - Enrico Guarnera
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, Singapore 138671, Singapore
| | - Zejun Zheng
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, Singapore 138671, Singapore
| | - Birgit Eisenhaber
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, Singapore 138671, Singapore
| | - Frank Eisenhaber
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, Singapore 138671, Singapore; School of Computer Engineering (SCE), Nanyang Technological University (NTU), 50 Nanyang Drive, Singapore 637553, Singapore
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37
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Novel mutations in SLC30A2 involved in the pathogenesis of transient neonatal zinc deficiency. Pediatr Res 2016; 80:586-94. [PMID: 27304099 DOI: 10.1038/pr.2016.108] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 03/22/2016] [Indexed: 11/08/2022]
Abstract
BACKGROUND Infants are vulnerable to zinc deficiency. Thus, abnormally low breast milk zinc levels cause transient neonatal zinc deficiency (TNZD) in breast-fed infants. TNZD has been considered to be rare because of a paucity of citations in the published literature. However, recent studies of affected mothers identified four missense mutations in the solute carrier family 30 member 2 gene (SLC30A2), which encodes the zinc transporter, ZnT2. METHODS Genetic analyses of SLC30A2/ZnT2 in three Japanese mothers secreting low-zinc milk (whose infants developed TNZD) were performed. The effects of identified mutations were examined in a cell-based assay. Furthermore, 31 single-nucleotide polymorphisms (SNPs) in SLC30A2/ZnT2 were evaluated for their potential involvement in low-zinc levels in milk. RESULTS Each mother had a different novel heterozygous mutation in SLC30A2/ZnT2. One mutation reduced splicing efficiency of the SLC30A2/ZnT2 transcript, and all ZnT2 mutants were defective in zinc transport and were unstable in cells. Moreover, four SNPs caused a significant loss of zinc-transport activity, similar to that in disease-causing ZnT2 mutants. CONCLUSION Our results indicate that many SLC30A2/ZnT2 mutations cause or potentially cause TNZD. Genetic information concerning TNZD pathogenesis is limited, and our results suggest that the TNZD frequency may be higher than previously thought.
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Berezovsky IN, Guarnera E, Zheng Z. Basic units of protein structure, folding, and function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 128:85-99. [PMID: 27697476 DOI: 10.1016/j.pbiomolbio.2016.09.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/05/2016] [Accepted: 09/26/2016] [Indexed: 10/20/2022]
Abstract
Study of the hierarchy of domain structure with alternative sets of domains and analysis of discontinuous domains, consisting of remote segments of the polypeptide chain, raised a question about the minimal structural unit of the protein domain. The hypothesis on the decisive role of the polypeptide backbone in determining the elementary units of globular proteins have led to the discovery of closed loops. It is reviewed here how closed loops form the loop-n-lock structure of proteins, providing the foundation for stability and designability of protein folds/domain and underlying their co-translational folding. Simplified protein sequences are considered here with the aim to explore the basic principles that presumably dominated the folding and stability of proteins in the early stages of structural evolution. Elementary functional loops (EFLs), closed loops with one or few catalytic residues, are, in turn, units of the protein function. They are apparent descendants of the prebiotic ring-like peptides, which gave rise to the first functional folds/domains being fused in the beginning of the evolution of protein structure. It is also shown how evolutionary relations between protein functional superfamilies and folds delineated with the help of EFLs can contribute to establishing the rules for design of desired enzymatic functions. Generalized descriptors of the elementary functions are proposed to be used as basic units in the future computational design.
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Affiliation(s)
- Igor N Berezovsky
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, 138671, Singapore; Department of Biological Sciences (DBS), National University of Singapore (NUS), 8 Medical Drive, 117579, Singapore.
| | - Enrico Guarnera
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, 138671, Singapore
| | - Zejun Zheng
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, 138671, Singapore
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Ackland ML, Michalczyk AA. Zinc and infant nutrition. Arch Biochem Biophys 2016; 611:51-57. [PMID: 27317042 DOI: 10.1016/j.abb.2016.06.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/23/2016] [Accepted: 06/13/2016] [Indexed: 01/12/2023]
Abstract
Zinc is essential for a wide variety of cellular processes in all cells. It is a critical dietary nutrient, particularly in the early stages of life. In the early neonatal period, adequate sources of zinc can be obtained from breast milk. In rare circumstances, the mammary gland produces zinc deficient milk that is potentially lethal for exclusively breast-fed infants. This can be overcome by zinc supplementation to the infant. Alterations to key zinc transporters provide insights into the mechanisms of cellular zinc homeostasis. The bioavailability of zinc in food depends on the presence of constituents that may complex zinc. In many countries, zinc deficiency is a major health issue due to poor nourishment. Young children are particularly affected. Zinc deficiency can impair immune function and contributes to the global burden of infectious diseases including diarrhoea, pneumonia and malaria. Furthermore, zinc deficiency may extend its influence across generations by inducing epigenetic effects that alter the expression of genes. This review discusses the significance of adequate zinc nutrition in infants, factors that influence zinc nutrition, the consequences of zinc deficiency, including its contribution to the global burden of disease, and addresses some of the knowledge gaps in zinc biology.
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Affiliation(s)
- M Leigh Ackland
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria 3125, Australia.
| | - Agnes A Michalczyk
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria 3125, Australia
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Golan Y, Itsumura N, Glaser F, Berman B, Kambe T, Assaraf YG. Molecular Basis of Transient Neonatal Zinc Deficiency: NOVEL ZnT2 MUTATIONS DISRUPTING ZINC BINDING AND PERMEATION. J Biol Chem 2016; 291:13546-59. [PMID: 27137936 DOI: 10.1074/jbc.m116.732693] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Indexed: 11/06/2022] Open
Abstract
A gradually increasing number of transient neonatal zinc deficiency (TNZD) cases was recently reported, all of which were associated with inactivating ZnT2 mutations. Here we characterized the impact of three novel heterozygous ZnT2 mutations G280R, T312M, and E355Q, which cause TNZD in exclusively breastfed infants of Japanese mothers. We used the bimolecular fluorescence complementation (BiFC) assay to provide direct visual evidence for the in situ dimerization of these ZnT2 mutants, and to explore their subcellular localization. Moreover, using three complementary functional assays, zinc accumulation using BiFC-Zinquin and Zinpyr-1 fluorescence as well as zinc toxicity assay, we determined the impact of these ZnT2 mutations on vesicular zinc accumulation. Although all three mutants formed homodimers with the wild type (WT) ZnT2 and retained substantial vesicular localization, as well as vesicular zinc accumulation, they had no dominant-negative effect over the WT ZnT2. Furthermore, using advanced bioinformatics, structural modeling, and site-directed mutagenesis we found that these mutations localized at key residues, which play an important physiological role in zinc coordination (G280R and E355Q) and zinc permeation (T312M). Collectively, our findings establish that some heterozygous loss of function ZnT2 mutations disrupt zinc binding and zinc permeation, thereby suggesting a haploinsufficiency state for the unaffected WT ZnT2 allele in TNZD pathogenesis. These results highlight the burning need for the development of a suitable genetic screen for the early diagnosis of TNZD to prevent morbidity.
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Affiliation(s)
- Yarden Golan
- From the Department of Biology, Fred Wyszkowski Cancer Research Laboratory and
| | - Naoya Itsumura
- the Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Fabian Glaser
- the Bioinformatics Knowledge Unit, The Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion, Haifa 32000, Israel and
| | - Bluma Berman
- From the Department of Biology, Fred Wyszkowski Cancer Research Laboratory and
| | - Taiho Kambe
- the Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yehuda G Assaraf
- From the Department of Biology, Fred Wyszkowski Cancer Research Laboratory and
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Kimura T, Kambe T. The Functions of Metallothionein and ZIP and ZnT Transporters: An Overview and Perspective. Int J Mol Sci 2016; 17:336. [PMID: 26959009 PMCID: PMC4813198 DOI: 10.3390/ijms17030336] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 12/18/2022] Open
Abstract
Around 3000 proteins are thought to bind zinc in vivo, which corresponds to ~10% of the human proteome. Zinc plays a pivotal role as a structural, catalytic, and signaling component that functions in numerous physiological processes. It is more widely used as a structural element in proteins than any other transition metal ion, is a catalytic component of many enzymes, and acts as a cellular signaling mediator. Thus, it is expected that zinc metabolism and homeostasis have sophisticated regulation, and elucidating the underlying molecular basis of this is essential to understanding zinc functions in cellular physiology and pathogenesis. In recent decades, an increasing amount of evidence has uncovered critical roles of a number of proteins in zinc metabolism and homeostasis through influxing, chelating, sequestrating, coordinating, releasing, and effluxing zinc. Metallothioneins (MT) and Zrt- and Irt-like proteins (ZIP) and Zn transporters (ZnT) are the proteins primarily involved in these processes, and their malfunction has been implicated in a number of inherited diseases such as acrodermatitis enteropathica. The present review updates our current understanding of the biological functions of MTs and ZIP and ZnT transporters from several new perspectives.
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Affiliation(s)
- Tomoki Kimura
- Department of Life Science, Faculty of Science and Engineering, Setsunan University, Neyagawa, Osaka 572-8508, Japan.
| | - Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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Hashimoto A, Nakagawa M, Tsujimura N, Miyazaki S, Kizu K, Goto T, Komatsu Y, Matsunaga A, Shirakawa H, Narita H, Kambe T, Komai M. Properties of Zip4 accumulation during zinc deficiency and its usefulness to evaluate zinc status: a study of the effects of zinc deficiency during lactation. Am J Physiol Regul Integr Comp Physiol 2016; 310:R459-68. [DOI: 10.1152/ajpregu.00439.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/18/2015] [Indexed: 11/22/2022]
Abstract
Systemic and cellular zinc homeostasis is elaborately controlled by ZIP and ZnT zinc transporters. Therefore, detailed characterization of their expression properties is of importance. Of these transporter proteins, Zip4 functions as the primarily important transporter to control systemic zinc homeostasis because of its indispensable function of zinc absorption in the small intestine. In this study, we closely investigated Zip4 protein accumulation in the rat small intestine in response to zinc status using an anti-Zip4 monoclonal antibody that we generated and contrasted this with the zinc-responsive activity of the membrane-bound alkaline phosphatase (ALP). We found that Zip4 accumulation is more rapid in response to zinc deficiency than previously thought. Accumulation increased in the jejunum as early as 1 day following a zinc-deficient diet. In the small intestine, Zip4 protein expression was higher in the jejunum than in the duodenum and was accompanied by reduction of ALP activity, suggesting that the jejunum can become zinc deficient more easily. Furthermore, by monitoring Zip4 accumulation levels and ALP activity in the duodenum and jejunum, we reasserted that zinc deficiency during lactation may transiently alter plasma glucose levels in the offspring in a sex-specific manner, without affecting homeostatic control of zinc metabolism. This confirms that zinc nutrition during lactation is extremely important for the health of the offspring. These results reveal that rapid Zip4 accumulation provides a significant conceptual advance in understanding the molecular basis of systemic zinc homeostatic control, and that properties of Zip4 protein accumulation are useful to evaluate zinc status closely.
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Affiliation(s)
- Ayako Hashimoto
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Miki Nakagawa
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Natsuki Tsujimura
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Shiho Miyazaki
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kumiko Kizu
- Department of Life and Living, Osaka Seikei College, Osaka, Japan; and
| | - Tomoko Goto
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Yusuke Komatsu
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Ayu Matsunaga
- Department of Food Science, Kyoto Women's University, Kyoto, Japan
| | - Hitoshi Shirakawa
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Hiroshi Narita
- Department of Food Science, Kyoto Women's University, Kyoto, Japan
| | - Taiho Kambe
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Michio Komai
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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43
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Yasuda H, Tsutsui T. Infants and elderlies are susceptible to zinc deficiency. Sci Rep 2016; 6:21850. [PMID: 26912464 PMCID: PMC4766432 DOI: 10.1038/srep21850] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 01/15/2016] [Indexed: 02/07/2023] Open
Abstract
The importance of zinc for human health has been recognized since the early 1960s, but today there is little concern about zinc deficiency in developed countries. In this study, we measured the zinc concentration in hair from 28,424 Japanese subjects (18,812 females and 9,612 males) and found that 1,754 subjects (6.17%) had zinc concentrations lower than 2 standard deviations (86.3 ppm) below the control reference range, which qualifies as zinc deficiency. In particular, a considerable proportion of elderlies and children (20% or more) were found to have marginal to severe zinc deficiency. A zinc concentration of 9.7 ppm was the lowest observed in a 51-year-old woman; this concentration was approximately 1/13 of the mean reference level. The prevalence of zinc deficiency in adults increased with aging to a maximum of 19.7% by the 8(th) decade of life, and decreased to 3.4% above 90-year-old. The proportion of zinc deficiency in infants 0-4 years was 36.5% in males and 47.3% in females; these percentages were higher than the maximum prevalence in elderly subjects. These findings suggest that infants and elderlies are prone to zinc deficiency and that intervention of zinc deficiency is necessary for normal human development, health and longevity.
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44
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Zhao Y, Feresin RG, Falcon-Perez JM, Salazar G. Differential Targeting of SLC30A10/ZnT10 Heterodimers to Endolysosomal Compartments Modulates EGF-Induced MEK/ERK1/2 Activity. Traffic 2016; 17:267-88. [PMID: 26728129 DOI: 10.1111/tra.12371] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 12/24/2015] [Accepted: 12/24/2015] [Indexed: 12/14/2022]
Abstract
The solute carrier 30A (SLC30A) family of zinc exporters transports zinc into the lumen of intracellular organelles in order to prevent zinc toxicity. We reported that formation of tyrosine dimers is required for ZnT3 (zinc transporter 3) zinc transport activity and targeting to synaptic-like microvesicles (SLMVs) in PC12 cells and the formation of ZnT3/ZnT10 heterodimers. Here, we focused on ZnT10 to determine the role of heterodimerization in the sorting of ZnTs in the endolysosomal pathway. Using cell fractionation, immunoprecipitation and immunofluorescence approaches, we found that ZnT10 resides in transferrin receptor and Rab5-positive endosomes and forms covalent heterodimers and oligomers with ZnT2, ZnT3 and ZnT4. The interaction of ZnT10 with ZnT3, mediated by dityrosine bonds, was unable to target ZnT10 into SLMVs in vitro or into synaptic vesicles isolated from mouse brain in vivo. However, ZnT3/ZnT10 heterodimers regulate epidermal growth factor receptor (EGF-R) signaling by increasing the phosphorylation of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK1/2), but not EGF-R, C-Raf or Akt phosphorylation in response to EGF. Further, mutation of tyrosine 4 in ZnT10 reduced ZnT3/ZnT10 dityrosine-mediated heterodimerization and zinc transport, as well as MEK and ERK1/2 phosphorylation, which were also reduced by the zinc chelator TPEN. Phosphorylation of these kinases is likely to occur in the cytosol as no differences in phosphorylation were observed in membrane fractions of control and ZnT3/ZnT10-expressing cells. We propose that ZnT10 plays a role in signal transduction, which is mediated by homo and heterodimerization with other ZnTs.
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Affiliation(s)
- Yitong Zhao
- The Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Rafaela G Feresin
- The Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA.,Department of Dietetics and Nutrition, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Juan M Falcon-Perez
- Exosomes Lab, Metabolomics Unit, CIC bioGUNE, CIBErehd, Derio, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Gloria Salazar
- The Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA.,Department of Medicine, Division of Cardiology, Emory University, Atlanta, GA, USA
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Alam S, Hennigar SR, Gallagher C, Soybel DI, Kelleher SL. Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction. J Mammary Gland Biol Neoplasia 2015; 20:159-72. [PMID: 26293594 DOI: 10.1007/s10911-015-9338-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 07/22/2015] [Indexed: 11/29/2022] Open
Abstract
The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36% of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D(103)E and T(288)S) were identified with high frequency (9 and 16%, respectively) and expression of T(288)S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A(28)D, K(66)N, Q(71)H, D(103)E, A(105)P, Q(137)H, T(288)S and T(312)K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either 'loss-of-function' or 'gain-of-function', and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.
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Affiliation(s)
- Samina Alam
- Department of Cellular and Molecular Physiology, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA
- Department of Surgery, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA
| | - Stephen R Hennigar
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Carla Gallagher
- Department of Public Health Sciences, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA
| | - David I Soybel
- Department of Cellular and Molecular Physiology, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA
- Department of Surgery, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA
| | - Shannon L Kelleher
- Department of Cellular and Molecular Physiology, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA.
- Department of Pharmacology, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA.
- Department of Surgery, The Pennsylvania State University Hershey College of Medicine, Hershey, PA, USA.
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA.
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McCormick NH, Lee S, Hennigar SR, Kelleher SL. ZnT4 (SLC30A4)-null ("lethal milk") mice have defects in mammary gland secretion and hallmarks of precocious involution during lactation. Am J Physiol Regul Integr Comp Physiol 2015; 310:R33-40. [PMID: 26538236 DOI: 10.1152/ajpregu.00315.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 11/02/2015] [Indexed: 02/01/2023]
Abstract
During lactation, highly specialized secretory mammary epithelial cells (MECs) produce and secrete huge quantities of nutrients and nonnutritive factors into breast milk. The zinc (Zn) transporter ZnT4 (SLC30A4) transports Zn into the trans-Golgi apparatus for lactose synthesis, and across the apical cell membrane for efflux from MECs into milk. This is consistent with observations in "lethal milk" (lm/lm) mice, which have a truncation mutation in SLC30A4, and present with not only low milk Zn concentration, but also smaller mammary glands, decreased milk volume, and lactation failure by lactation day 2. However, the molecular underpinnings of these defects are not understood. Here, we used lactating C57BL/6J(lm/lm) (ZnT4-null) mice to explore the consequences of a ZnT4-null phenotype on mammary gland function during early lactation. Lactating C57BL/6J(lm/lm) mice had significantly fewer, smaller, and collapsed alveoli comprising swollen, lipid-filled MECs during early lactation. These defects were associated with decreased Akt expression and STAT5 activation, indicative of defects in MEC secretion. In addition, increased expression of ZnT2, TNF-α, and cleaved e-cadherin concomitant with increased activation of STAT3 implicated the loss of ZnT4 in precocious activation of involution. Collectively, our study indicates that the loss of ZnT4 has profound consequences on MEC secretion and may promote tissue remodeling in the mammary gland during early lactation.
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Affiliation(s)
- Nicholas H McCormick
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Sooyeon Lee
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania
| | - Stephen R Hennigar
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Shannon L Kelleher
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania; Department of Pharmacology, Penn State Hershey College of Medicine, Hershey, Pennsylvania; Department of Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania; and Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
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Kumar L, Michalczyk A, McKay J, Ford D, Kambe T, Hudek L, Varigios G, Taylor PE, Ackland ML. Altered expression of two zinc transporters, SLC30A5 and SLC30A6, underlies a mammary gland disorder of reduced zinc secretion into milk. GENES AND NUTRITION 2015; 10:487. [PMID: 26319140 DOI: 10.1007/s12263-015-0487-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 08/14/2015] [Indexed: 01/24/2023]
Abstract
Two cases of zinc deficiency in breastfed neonates were investigated where zinc levels in the mothers' milk were reduced by more than 75 % compared to normal. The objective of this study was to find the molecular basis of the maternal zinc deficiency condition. Significant reductions in mRNA expression and protein levels of the zinc transporters SLC30A5 and SLC30A6 were found in maternal tissue, suggesting a causal link to the zinc-deficient milk. Novel splice variants of the SLC30A6 transcript were detected. No modifications were found in coding regions, or in transcription binding sites of promoter regions or in 5' and 3' untranslated regions of both transporters in lymphoblasts and fibroblasts isolated from both mothers. Altered DNA methylation in SLC30A5 at two CpG sites was detected and may account for the reduced levels of SLC30A5 mRNA and protein in lymphoblasts. Reduced SLC30A6 mRNA and protein levels in lymphoblasts may be secondary to reduced SLC30A5 expression, as they function as a heterodimer in zinc transport. In conclusion, two cases of zinc deficiency are linked to low levels of the SLC30A5 and SLC30A6 zinc transporters. These two zinc transporters have not been previously associated with zinc deficiency in milk.
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Affiliation(s)
- Loveleen Kumar
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
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Kambe T, Tsuji T, Hashimoto A, Itsumura N. The Physiological, Biochemical, and Molecular Roles of Zinc Transporters in Zinc Homeostasis and Metabolism. Physiol Rev 2015; 95:749-84. [DOI: 10.1152/physrev.00035.2014] [Citation(s) in RCA: 556] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Zinc is involved in a variety of biological processes, as a structural, catalytic, and intracellular and intercellular signaling component. Thus zinc homeostasis is tightly controlled at the whole body, tissue, cellular, and subcellular levels by a number of proteins, with zinc transporters being particularly important. In metazoan, two zinc transporter families, Zn transporters (ZnT) and Zrt-, Irt-related proteins (ZIP) function in zinc mobilization of influx, efflux, and compartmentalization/sequestration across biological membranes. During the last two decades, significant progress has been made in understanding the molecular properties, expression, regulation, and cellular and physiological roles of ZnT and ZIP transporters, which underpin the multifarious functions of zinc. Moreover, growing evidence indicates that malfunctioning zinc homeostasis due to zinc transporter dysfunction results in the onset and progression of a variety of diseases. This review summarizes current progress in our understanding of each ZnT and ZIP transporter from the perspective of zinc physiology and pathogenesis, discussing challenging issues in their structure and zinc transport mechanisms.
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Affiliation(s)
- Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Tokuji Tsuji
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Ayako Hashimoto
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Naoya Itsumura
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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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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Golan Y, Berman B, Assaraf YG. Heterodimerization, altered subcellular localization, and function of multiple zinc transporters in viable cells using bimolecular fluorescence complementation. J Biol Chem 2015; 290:9050-63. [PMID: 25657003 DOI: 10.1074/jbc.m114.617332] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Indexed: 01/19/2023] Open
Abstract
Zinc plays a crucial role in numerous key physiological functions. Zinc transporters (ZnTs) mediate zinc efflux and compartmentalization in intracellular organelles; thus, ZnTs play a central role in zinc homeostasis. We have recently shown the in situ dimerization and function of multiple normal and mutant ZnTs using bimolecular fluorescence complementation (BiFC). Prompted by these findings, we here uncovered the heterodimerization, altered subcellular localization, and function of multiple ZnTs in live cells using this sensitive BiFC technique. We show that ZnT1, -2, -3, and -4 form stable heterodimers at distinct intracellular compartments, some of which are completely different from their homodimer localization. Specifically, unlike the plasma membrane (PM) localization of ZnT1 homodimers, ZnT1-ZnT3 heterodimers localized at intracellular vesicles. Furthermore, upon heterodimerization with ZnT1, the zinc transporters ZnT2 and ZnT4 surprisingly localized at the PM, as opposed to their vesicular homodimer localization. We further demonstrate the deleterious effect that the G87R-ZnT2 mutation, associated with transient neonatal zinc deficiency, has on ZnT1, ZnT3, and ZnT4 upon heterodimerization. The functionality of the various ZnTs was assessed by the dual BiFC-Zinquin assay. We also undertook a novel transfection competition assay with ZnT cDNAs to confirm that the driving force for heterodimer formation is the core structure of ZnTs and not the BiFC tags. These findings uncover a novel network of homo- and heterodimers of ZnTs with distinct subcellular localizations and function, hence highlighting their possible role in zinc homeostasis under physiological and pathological conditions.
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Affiliation(s)
- Yarden Golan
- From the Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Bluma Berman
- From the Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Yehuda G Assaraf
- From the Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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