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Bizup B, Brutsaert S, Cunningham CL, Thathiah A, Tzounopoulos T. Cochlear zinc signaling dysregulation is associated with noise-induced hearing loss, and zinc chelation enhances cochlear recovery. Proc Natl Acad Sci U S A 2024; 121:e2310561121. [PMID: 38354264 PMCID: PMC10895357 DOI: 10.1073/pnas.2310561121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 01/08/2024] [Indexed: 02/16/2024] Open
Abstract
Exposure to loud noise triggers sensory organ damage and degeneration that, in turn, leads to hearing loss. Despite the troublesome impact of noise-induced hearing loss (NIHL) in individuals and societies, treatment strategies that protect and restore hearing are few and insufficient. As such, identification and mechanistic understanding of the signaling pathways involved in NIHL are required. Biological zinc is mostly bound to proteins, where it plays major structural or catalytic roles; however, there is also a pool of unbound, mobile (labile) zinc. Labile zinc is mostly found in vesicles in secretory tissues, where it is released and plays a critical signaling role. In the brain, labile zinc fine-tunes neurotransmission and sensory processing. However, injury-induced dysregulation of labile zinc signaling contributes to neurodegeneration. Here, we tested whether zinc dysregulation occurs and contributes to NIHL in mice. We found that ZnT3, the vesicular zinc transporter responsible for loading zinc into vesicles, is expressed in cochlear hair cells and the spiral limbus, with labile zinc also present in the same areas. Soon after noise trauma, ZnT3 and zinc levels are significantly increased, and their subcellular localization is vastly altered. Disruption of zinc signaling, either via ZnT3 deletion or pharmacological zinc chelation, mitigated NIHL, as evidenced by enhanced auditory brainstem responses, distortion product otoacoustic emissions, and number of hair cell synapses. These data reveal that noise-induced zinc dysregulation is associated with cochlear dysfunction and recovery after NIHL, and point to zinc chelation as a potential treatment for mitigating NIHL.
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Affiliation(s)
- Brandon Bizup
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Sofie Brutsaert
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Christopher L Cunningham
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Amantha Thathiah
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Thanos Tzounopoulos
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
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Kang BS, Suh SW, Yang DY, Choi BY, Lee WK. Expression and Distribution of Free Zinc in Penile Erectile Tissue. World J Mens Health 2023; 41:155-163. [PMID: 35274500 PMCID: PMC9826916 DOI: 10.5534/wjmh.210168] [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: 08/30/2021] [Revised: 11/16/2021] [Accepted: 12/15/2021] [Indexed: 01/21/2023] Open
Abstract
PURPOSE Several studies have shown that zinc has a significant influence on erectile function. However, no studies evaluating the cellular distribution of free zinc in penile erectile tissue have been performed. Therefore, this study aimed to test whether free zinc is present in penile tissue and whether it may be involved in the electrical stimulation (ES)-induced penile erection. MATERIALS AND METHODS The subjects for this study were 26 young (8-week-old) male C57BL/6J mice. After the cavernous nerve was exposed through a midline stomach incision, 14 mice received ES of the cavernous nerve (ES group), whereas 12 mice did not (control group). Intracavernous pressure (ICP) (consisting of 10 V at a duration of 1 min, frequency of 12 Hz and a pulse width of 1 m/s) was recorded during ES. Immediately after ICP was recorded, penile tissues were harvested for histological and biochemical analysis, including analysis of zinc transporter 3 (ZnT3) and intracellular free zinc levels. RESULTS The expression of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS) in penile tissue was significantly greater in the ES group than in the control group (p=0.036 and 0.016, respectively). And then, ZnT3 and intracellular free zinc were present in the penile tissue of both groups. However, ZnT3 immunofluorescence in the ES group was more intense in the dorsal nerve bundle (22% increase, p=0.032). The ES group also showed higher intensity N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ) fluorescence signals indicative of intracellular free zinc level in the penile tissue compared to the control group (49% increase in dorsal nerve bundle, p=0.001; 50% increase in corpus cavernosum, p=0.001). CONCLUSIONS The results of the study supported the expression and distribution of free zinc in penile tissue and increased levels after penile erection. Therefore, this study provides anatomical evidence for the potential role of free zinc in penile erection.
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Affiliation(s)
- Beom Seok Kang
- Department of Physiology, Hallym University College of Medicine, Chuncheon, Korea
| | - Sang Won Suh
- Department of Physiology, Hallym University College of Medicine, Chuncheon, Korea
| | - Dae Yul Yang
- Department of Urology, Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Bo Young Choi
- Department of Physiology, Hallym University College of Medicine, Chuncheon, Korea
| | - Won Ki Lee
- Department of Urology, Hallym University Chuncheon Sacred Heart Hospital, Chuncheon, Korea
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3
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Escobar A, Styrpejko DJ, Ali S, Cuajungco MP. Transmembrane 163 (TMEM163) protein interacts with specific mammalian SLC30 zinc efflux transporter family members. Biochem Biophys Rep 2022; 32:101362. [PMID: 36204728 PMCID: PMC9530847 DOI: 10.1016/j.bbrep.2022.101362] [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: 07/15/2022] [Revised: 09/11/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
Recently, we reported that TMEM163 is a zinc efflux transporter that likely belongs to the mammalian solute carrier 30 (Slc30/ZnT) subfamily of the cation diffusion facilitator (CDF) protein superfamily. We hypothesized that human TMEM163 forms functional heterodimers with certain ZNT proteins based on their overlapping subcellular localization with TMEM163 and previous reports that some ZNT monomers interact with each other. In this study, we heterologously expressed individual constructs with a unique peptide tag containing TMEM163, ZNT1, ZNT2, ZNT3, and ZNT4 (negative control) or co-expressed TMEM163 with each ZNT in cultured cells for co-immunoprecipitation (co-IP) experiments. We also co-expressed TMEM163 with two different peptide tags as a positive co-IP control. Western blot analyses revealed that TMEM163 dimerizes with itself but that it also heterodimerizes with ZNT1, ZNT2, ZNT3, and ZNT4 proteins. Confocal microscopy revealed that TMEM163 and ZNT proteins partially co-localize in cells, suggesting that they exist as homodimers and heterodimers in their respective subcellular sites. Functional zinc flux assays using Fluozin-3 and Newport Green dyes show that TMEM163/ZNT heterodimers exhibit similar efflux function as TMEM163 homodimers. Cell surface biotinylation revealed that the plasma membrane localization of TMEM163 is not markedly influenced by ZNT co-expression. Overall, our results show that the interaction between TMEM163 and distinct ZNT proteins is physiologically relevant and that their heterodimerization may serve to increase the functional diversity of zinc effluxers within specific tissues or cell types. TMEM163 protein heterodimerizes with ZNT1, ZNT2, ZNT3 and ZNT4 zinc efflux transporters. Partial co-localization of TMEM163 and ZNT proteins in cells suggests distinct roles as homodimers and heterodimers. Zinc efflux activity of TMEM163 or ZNT protein homodimers did not differ from their TMEM163/ZNT heterodimer counterparts. TMEM163/ZNT heterodimerization attests to the role of TMEM163 as a bona fide SLC30 protein family member.
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Affiliation(s)
| | | | - Saima Ali
- Department of Biological Science, USA
| | - Math P. Cuajungco
- Department of Biological Science, USA,Center for Applied Biotechnology Studies, California State University Fullerton, CA, 92831, USA,Corresponding author. Department of Biological Science, California State University Fullerton, 800 North State College Blvd, Fullerton, CA, 92831, USA.
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4
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Wilmaerts D, De Loose PJ, Vercauteren S, De Smedt S, Verstraeten N, Michiels J. Functional analysis of cysteine residues of the Hok/Gef type I toxins in Escherichia coli. FEMS Microbiol Lett 2021; 368:6296419. [PMID: 34114031 DOI: 10.1093/femsle/fnab069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 06/08/2021] [Indexed: 01/04/2023] Open
Abstract
The Hok/Gef family consists of structurally similar, single-span membrane peptides that all contain a positively charged N-terminal domain, an α-helix and a periplasmic C-terminal domain. Hok/Gef peptides have previously been described to play distinct physiological roles. Indeed, while HokB has been implicated in bacterial persistence, other members of the Hok/Gef family are known to induce cell lysis. However, the generalizability of previously published studies is problematic, as they have all used different expression systems. Therefore, we conducted a systematic study of the nine Hok/Gef peptides of Escherichia coli. We observed rapid cell death following expression of hokA, hokC, hokD, hokE, pndA1, hok or srnB, while expression of hokB or pndA2 does not result in cell lysis. A remarkable feature of Hok/Gef peptides is the presence of conserved periplasmic tyrosine and/or cysteine residues. For the HokB peptide, one of these residues has previously been implicated in intermolecular dimerization, which is essential for HokB to exert its role in persistence. To assess the role of the periplasmic cysteine and tyrosine residues in other Hok/Gef peptides and to decipher whether these residues determine peptide toxicity, an array of substitution mutants were constructed. We found that these residues are important activators of toxicity for Hok, HokA and HokE peptides. Despite the loss of the cell killing phenotype in HokS31_Y48, HokAS29_S46 and HokES29_Y46, these peptides do not exert a persister phenotype. More research is needed to fully comprehend why HokB is the sole peptide of the Hok/Gef family that mediates persistence.
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Affiliation(s)
- Dorien Wilmaerts
- KU Leuven Centre of Microbial and Plant Genetics, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Pieter-Jan De Loose
- KU Leuven Centre of Microbial and Plant Genetics, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Silke Vercauteren
- KU Leuven Centre of Microbial and Plant Genetics, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Sandrien De Smedt
- KU Leuven Centre of Microbial and Plant Genetics, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Natalie Verstraeten
- KU Leuven Centre of Microbial and Plant Genetics, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Jan Michiels
- KU Leuven Centre of Microbial and Plant Genetics, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
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5
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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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6
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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: 99] [Impact Index Per Article: 33.0] [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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7
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Krall RF, Tzounopoulos T, Aizenman E. The Function and Regulation of Zinc in the Brain. Neuroscience 2021; 457:235-258. [PMID: 33460731 DOI: 10.1016/j.neuroscience.2021.01.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 12/31/2022]
Abstract
Nearly sixty years ago Fredrich Timm developed a histochemical technique that revealed a rich reserve of free zinc in distinct regions of the brain. Subsequent electron microscopy studies in Timm- stained brain tissue found that this "labile" pool of cellular zinc was highly concentrated at synaptic boutons, hinting a possible role for the metal in synaptic transmission. Although evidence for activity-dependent synaptic release of zinc would not be reported for another twenty years, these initial findings spurred decades of research into zinc's role in neuronal function and revealed a diverse array of signaling cascades triggered or regulated by the metal. Here, we delve into our current understanding of the many roles zinc plays in the brain, from influencing neurotransmission and sensory processing, to activating both pro-survival and pro-death neuronal signaling pathways. Moreover, we detail the many mechanisms that tightly regulate cellular zinc levels, including metal binding proteins and a large array of zinc transporters.
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Affiliation(s)
- Rebecca F Krall
- Department of Neurobiology, University of Pittsburgh School of Medicine, USA; Department of Otolaryngology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, USA
| | - Thanos Tzounopoulos
- Department of Otolaryngology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA.
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, USA.
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8
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Groeneweg S, van den Berge A, Lima de Souza EC, Meima ME, Peeters RP, Visser WE. Insights Into the Mechanism of MCT8 Oligomerization. J Endocr Soc 2020; 4:bvaa080. [PMID: 32724870 PMCID: PMC7375341 DOI: 10.1210/jendso/bvaa080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 06/12/2020] [Indexed: 12/03/2022] Open
Abstract
Mutations in the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) result in MCT8 deficiency, characterized by severe intellectual and motor disability. The MCT8 protein is predicted to have 12 transmembrane domains (TMDs) and is expressed as monomers, homodimers, and homo-oligomers. This study aimed to delineate the mechanism of MCT8 oligomerization. Coimmunoprecipitation studies demonstrated that lithium dodecyl sulfate effectively disrupts MCT8 protein complexes, indicating the involvement of non-covalent interactions. Successive C-terminal truncations of the MCT8 protein altered the oligomerization pattern only if introduced in the N-terminal half of the protein (TMD1-6). The truncation at extracellular loop 1 (E206X) still allowed homodimerization, but completely abrogated homo-oligomerization, whereas both were preserved by the C231X mutant (at TMD2), suggesting that the minimally required oligomerization sites are located proximal of Cys231. However, mutant constructs lacking the intracellular N-terminus or TMD1 and 2 were still capable to form homo-oligomers. Therefore, other domains distal of Cys231 are also likely to be involved in the formation of extensive multidomain interactions. This hypothesis was supported by structural modeling. Despite multiple approaches, MCT8 oligomerization could not be fully abrogated unless a substantial part of the protein was removed, precluding detailed studies into its functional role. Together, our findings suggest that MCT8 oligomerization involves extensive noncovalent interactions between the N-terminal halves of MCT8 proteins. Most mutations identified in patients with MCT8 deficiency have only minor effects on MCT8 oligomerization and, thus, impaired oligomerization does not appear to be an important pathogenic mechanism.
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Affiliation(s)
- Stefan Groeneweg
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Amanda van den Berge
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Elaine C Lima de Souza
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Marcel E Meima
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Robin P Peeters
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - W Edward Visser
- Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
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9
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Eide DJ. Transcription factors and transporters in zinc homeostasis: lessons learned from fungi. Crit Rev Biochem Mol Biol 2020; 55:88-110. [PMID: 32192376 DOI: 10.1080/10409238.2020.1742092] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Zinc is an essential nutrient for all organisms because this metal serves as a critical structural or catalytic cofactor for many proteins. These zinc-dependent proteins are abundant in the cytosol as well as within organelles of eukaryotic cells such as the nucleus, mitochondria, endoplasmic reticulum, Golgi, and storage compartments such as the fungal vacuole. Therefore, cells need zinc transporters so that they can efficiently take up the metal and move it around within cells. In addition, because zinc levels in the environment can vary drastically, the activity of many of these transporters and other components of zinc homeostasis is regulated at the level of transcription by zinc-responsive transcription factors. Mechanisms of post-transcriptional control are also important for zinc homeostasis. In this review, the focus will be on our current knowledge of zinc transporters and their regulation by zinc-responsive transcription factors and other mechanisms in fungi because these organisms have served as useful paradigms of zinc homeostasis in all organisms. With this foundation, extension to other organisms will be made where warranted.
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Affiliation(s)
- David J Eide
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
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10
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Transmembrane 163 (TMEM163) protein effluxes zinc. Arch Biochem Biophys 2019; 677:108166. [PMID: 31697912 PMCID: PMC6864316 DOI: 10.1016/j.abb.2019.108166] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/09/2019] [Accepted: 10/31/2019] [Indexed: 01/19/2023]
Abstract
Recent investigations of rodent Tmem163 suggest that it binds to and transports zinc as a dimer, and that alanine mutagenesis of its two species-conserved aspartate (D123A/D127A) residues proposed to bind zinc, perturbs protein function. Direct corroboration, however, is lacking whether it is an influx or efflux transporter in cells. We hypothesized that human TMEM163 is a zinc effluxer based on its predicted protein characteristics. We used cultured human cell lines that either stably or transiently expressed TMEM163, and pre-loaded the cells with zinc to determine transport activity. We found that TMEM163-expressing cells exhibited significant reduction of intracellular zinc levels as evidenced by two zinc-specific fluorescent dyes and radionuclide zinc-65. The specificity of the fluorescence signal was confirmed upon treatment with TPEN, a high-affinity zinc chelator. Multiple sequence alignment and phylogenetic analyses showed that TMEM163 is related to distinct members of the cation diffusion facilitator (CDF) protein family. To further characterize the efflux function of TMEM163, we substituted alanine in two homologous aspartate residues (D124A/D128A) and performed site-directed mutagenesis of several conserved amino acid residues identified as non-synonymous single nucleotide polymorphism (S61R, S95C, S193P, and E286K). We found a significant reduction of zinc efflux upon cellular expression of D124A/D128A or E286K protein variant when compared with wild-type, suggesting that these particular amino acids are important for normal protein function. Taken together, our findings demonstrate that TMEM163 effluxes zinc, and it should now be designated ZNT11 as a new member of the mammalian CDF family of zinc efflux transporters.
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12
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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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13
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The role of zinc and its compounds in leukemia. J Biol Inorg Chem 2018; 23:347-362. [DOI: 10.1007/s00775-018-1545-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 02/09/2018] [Indexed: 12/23/2022]
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14
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Parsons DS, Hogstrand C, Maret W. The C-terminal cytosolic domain of the human zinc transporter ZnT8 and its diabetes risk variant. FEBS J 2018; 285:1237-1250. [PMID: 29430817 PMCID: PMC5947572 DOI: 10.1111/febs.14402] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/22/2017] [Accepted: 02/05/2018] [Indexed: 12/21/2022]
Abstract
A significant aspect of the control of cellular zinc in eukarya is its subcellular re‐distribution. One of the four human vesicular zinc transporters, ZnT8, supplies the millimolar zinc concentrations of insulin granules in pancreatic β‐cells, affecting insulin processing, crystallisation and secretion. ZnT8 has a transmembrane and a C‐terminal cytosolic domain; the latter has important functions and purportedly mediates protein–protein interactions, senses cytosolic zinc and/or channels zinc to the transport site in the transmembrane domain (TMD). A common variant W325R in the C‐terminal domain (CTD) increases the risk to develop type 2 diabetes and affects autoantibody specificity in type 1 diabetes. To investigate the differences between the two protein variants, we purified and biophysically characterised both variants of the ZnT8 CTD [R325 variant of ZnT8 CTD (aa267–369) (ZnT8cR) and W325 variant of ZnT8 CTD (aa267–369) (ZnT8cW)]. The domains fold independently of the TMD. Remarkably, the ZnT8cW variant (diabetes protection in the full‐length protein) is less thermostable than the ZnT8cR variant (diabetes risk in the full‐length protein). The ZnT8cW monomers associate with higher affinity. Both CTD variants bind zinc with a stoichiometry that differs from bacterial homologues, emphasising the limitation of the latter as models for the structure and function of the human proteins. The relatively small but reproducible differences between the two ZnT8 CTD variants begin to provide a molecular basis for the different diabetes susceptibility caused by the full‐length ZnT8 proteins.
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Affiliation(s)
- Douglas S Parsons
- Metal Metabolism Group, Departments of Biochemistry and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, UK
| | - Christer Hogstrand
- Metal Metabolism Group, Departments of Biochemistry and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, UK
| | - Wolfgang Maret
- Metal Metabolism Group, Departments of Biochemistry and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, UK
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15
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McAllister BB, Dyck RH. Zinc transporter 3 (ZnT3) and vesicular zinc in central nervous system function. Neurosci Biobehav Rev 2017. [DOI: 10.1016/j.neubiorev.2017.06.006] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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16
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Bafaro E, Liu Y, Xu Y, Dempski RE. The emerging role of zinc transporters in cellular homeostasis and cancer. Signal Transduct Target Ther 2017; 2:17029. [PMID: 29218234 PMCID: PMC5661630 DOI: 10.1038/sigtrans.2017.29] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/21/2017] [Accepted: 04/25/2017] [Indexed: 12/21/2022] Open
Abstract
Zinc is an essential micronutrient that plays a role in the structural or enzymatic functions of many cellular proteins. Cellular zinc homeostasis involves the opposing action of two families of metal transporters: the ZnT (SLC30) family that functions to reduce cytoplasmic zinc concentrations and the ZIP (SLC39) family that functions to increase cytoplasmic zinc concentrations. Fluctuations in intracellular zinc levels mediated by these transporter families affect signaling pathways involved in normal cell development, growth, differentiation and death. Consequently, changes in zinc transporter localization and function resulting in zinc dyshomeostasis have pathophysiological effects. Zinc dyshomeostasis has been implicated in the progression of cancer. Here we review recent progress toward understanding the structural basis for zinc transport by ZnT and ZIP family proteins, as well as highlight the roles of zinc as a signaling molecule in physiological conditions and in various cancers. As zinc is emerging as an important signaling molecule in the development and progression of cancer, the ZnT and ZIP transporters that regulate cellular zinc homeostasis are promising candidates for targeted cancer therapy.
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Affiliation(s)
- Elizabeth Bafaro
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Yuting Liu
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Yan Xu
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Robert E Dempski
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
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17
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Hara T, Takeda TA, Takagishi T, Fukue K, Kambe T, Fukada T. Physiological roles of zinc transporters: molecular and genetic importance in zinc homeostasis. J Physiol Sci 2017; 67:283-301. [PMID: 28130681 PMCID: PMC10717645 DOI: 10.1007/s12576-017-0521-4] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 01/04/2017] [Indexed: 02/07/2023]
Abstract
Zinc (Zn) is an essential trace mineral that regulates the expression and activation of biological molecules such as transcription factors, enzymes, adapters, channels, and growth factors, along with their receptors. Zn deficiency or excessive Zn absorption disrupts Zn homeostasis and affects growth, morphogenesis, and immune response, as well as neurosensory and endocrine functions. Zn levels must be adjusted properly to maintain the cellular processes and biological responses necessary for life. Zn transporters regulate Zn levels by controlling Zn influx and efflux between extracellular and intracellular compartments, thus, modulating the Zn concentration and distribution. Although the physiological functions of the Zn transporters remain to be clarified, there is growing evidence that Zn transporters are related to human diseases, and that Zn transporter-mediated Zn ion acts as a signaling factor, called "Zinc signal". Here we describe critical roles of Zn transporters in the body and their contribution at the molecular, biochemical, and genetic levels, and review recently reported disease-related mutations in the Zn transporter genes.
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Affiliation(s)
- Takafumi Hara
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Taka-Aki Takeda
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Teruhisa Takagishi
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Kazuhisa Fukue
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
| | - Toshiyuki Fukada
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.
- Division of Pathology, Department of Oral Diagnostic Sciences, School of Dentistry, Showa University, Tokyo, Japan.
- RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, Japan.
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18
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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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19
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The zinc transporter ZNT3 co-localizes with insulin in INS-1E pancreatic beta cells and influences cell survival, insulin secretion capacity, and ZNT8 expression. Biometals 2016; 29:287-98. [DOI: 10.1007/s10534-016-9915-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 02/05/2016] [Indexed: 01/21/2023]
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20
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Loss of synaptic Zn2+ transporter function increases risk of febrile seizures. Sci Rep 2015; 5:17816. [PMID: 26647834 PMCID: PMC4673435 DOI: 10.1038/srep17816] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 11/06/2015] [Indexed: 01/06/2023] Open
Abstract
Febrile seizures (FS) are the most common seizure syndrome and are potentially a prelude to more severe epilepsy. Although zinc (Zn(2+)) metabolism has previously been implicated in FS, whether or not variation in proteins essential for Zn(2+) homeostasis contributes to susceptibility is unknown. Synaptic Zn(2+) is co-released with glutamate and modulates neuronal excitability. SLC30A3 encodes the zinc transporter 3 (ZNT3), which is primarily responsible for moving Zn(2+) into synaptic vesicles. Here we sequenced SLC30A3 and discovered a rare variant (c.892C > T; p.R298C) enriched in FS populations but absent in population-matched controls. Functional analysis revealed a significant loss-of-function of the mutated protein resulting from a trafficking deficit. Furthermore, mice null for ZnT3 were more sensitive than wild-type to hyperthermia-induced seizures that model FS. Together our data suggest that reduced synaptic Zn(2+) increases the risk of FS and more broadly support the idea that impaired synaptic Zn(2+) homeostasis can contribute to neuronal hyperexcitability.
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21
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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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22
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Hennigar SR, Kelleher SL. TNFα Post-Translationally Targets ZnT2 to Accumulate Zinc in Lysosomes. J Cell Physiol 2015; 230:2345-50. [DOI: 10.1002/jcp.24992] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 03/18/2015] [Indexed: 01/10/2023]
Affiliation(s)
- Stephen R. Hennigar
- Department of Nutritional Sciences; The Pennsylvania State University; University Park; Pennsylvania
| | - Shannon L. Kelleher
- Department of Nutritional Sciences; The Pennsylvania State University; University Park; Pennsylvania
- Department of and Cell 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
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23
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Membrane transporters in self resistance of Cercospora nicotianae to the photoactivated toxin cercosporin. Curr Genet 2015; 61:601-20. [PMID: 25862648 DOI: 10.1007/s00294-015-0486-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 03/26/2015] [Accepted: 03/28/2015] [Indexed: 01/09/2023]
Abstract
The goal of this work is to characterize membrane transporter genes in Cercospora fungi required for autoresistance to the photoactivated, active-oxygen-generating toxin cercosporin they produce for infection of host plants. Previous studies implicated a role for diverse membrane transporters in cercosporin resistance. In this study, transporters identified in a subtractive cDNA library between a Cercospora nicotianae wild type and a cercosporin-sensitive mutant were characterized, including two ABC transporters (CnATR2, CnATR3), an MFS transporter (CnMFS2), a uracil transporter, and a zinc transport protein. Phylogenetic analysis showed that only CnATR3 clustered with transporters previously characterized to be involved in cercosporin resistance. Quantitative RT-PCR analysis of gene expression under conditions of cercosporin toxicity, however, showed that only CnATR2 was upregulated, thus this gene was selected for further characterization. Transformation and expression of CnATR2 in the cercosporin-sensitive fungus Neurospora crassa significantly increased cercosporin resistance. Targeted gene disruption of CnATR2 in the wild type C. nicotianae, however, did not decrease resistance. Expression analysis of other transporters in the cnatr2 mutant under conditions of cercosporin toxicity showed significant upregulation of the cercosporin facilitator protein gene (CFP), encoding an MFS transporter previously characterized as playing an important role in cercosporin autoresistance in Cercospora species. We conclude that cercosporin autoresistance in Cercospora is mediated by multiple genes, and that the fungus compensates for mutations by up-regulation of other resistance genes. CnATR2 may be a useful gene, alone or in addition to other known resistance genes, for engineering Cercospora resistance in crop plants.
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24
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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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25
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ZnT2 is a critical mediator of lysosomal-mediated cell death during early mammary gland involution. Sci Rep 2015; 5:8033. [PMID: 25620235 PMCID: PMC4306139 DOI: 10.1038/srep08033] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/22/2014] [Indexed: 01/13/2023] Open
Abstract
Mammary gland involution is the most dramatic example of physiological cell death. It occurs through an initial phase of lysosomal-mediated cell death (LCD) followed by mitochondrial-mediated apoptosis. Zinc (Zn) activates both LCD and apoptosis in vitro. The Zn transporter ZnT2 imports Zn into vesicles and mitochondria and ZnT2-overexpression activates cell death in mammary epithelial cells (MECs). We tested the hypothesis that ZnT2-mediated Zn transport is critical for mammary gland involution in mice. Following weaning, ZnT2 abundance increased in lysosomes and mitochondria, which paralleled Zn accumulation in each of these organelles. Adenoviral expression of ZnT2 in lactating mouse mammary glands in vivo increased Zn in lysosomes and mitochondria and activated LCD and apoptosis, promoting a profound reduction in MECs and alveoli. Injection of TNFα, a potent activator of early involution, into the mammary gland fat pads of lactating mice increased ZnT2 and Zn in lysosomes and activated premature involution. Exposure of cultured MECs to TNFα redistributed ZnT2 to lysosomes and increased lysosomal Zn, which activated lysosomal swelling, cathepsin B release, and LCD. Our data implicate ZnT2 as a critical mediator of cell death during involution and importantly, that as an initial involution signal, TNFα redistributes ZnT2 to lysosomes to activate LCD.
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26
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da Rocha TJ, Korb C, Schuch JB, Bamberg DP, de Andrade FM, Fiegenbaum M. SLC30A3 and SEP15 gene polymorphisms influence the serum concentrations of zinc and selenium in mature adults. Nutr Res 2014; 34:742-8. [PMID: 25249019 DOI: 10.1016/j.nutres.2014.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 08/04/2014] [Accepted: 08/22/2014] [Indexed: 01/15/2023]
Abstract
Because of their numerous roles in several biological processes, zinc and selenium are the most commonly studied micronutrients in the elderly. Therefore, we hypothesized that the polymorphisms in the genes that are responsible for the transport of zinc and selenium may have a genotype-dependent effect on the serum concentration of these micronutrients. The objective of this study was to determine the effects of solute carrier family 30 member 3 (SLC30A3) and 15-kd selenoprotein (SEP15) polymorphisms on zinc and selenium concentrations, respectively, in the serum. This cross-sectional study included 110 individuals who were aged 50 years or older. Serum micronutrient concentrations were determined by flame atomic absorption spectrophotometry (for zinc) and by atomic absorption spectrophotometry with a graphite furnace (for selenium). The single-nucleotide polymorphisms, rs73924411 and rs11126936 of the SLC30A3 gene and rs5859, rs5854, and rs561104 of the SEP15 gene, were examined by real-time polymerase chain reaction. Regarding rs11126936, the serum zinc concentration was lower in CC homozygotes (0.75 ± 0.31 mg/L) than in A carriers (0.89 ± 0.28 mg/L, P = .016). Concerning rs561104, the serum selenium concentration was higher in CC homozygotes (5.65 ± 1.11 μg/dL) compared with T carriers (4.88 ± 1.25 μg/dL, P = .044). Our results demonstrate the influence of SLC30A3 and SEP15 gene polymorphisms on the serum concentrations of zinc and selenium, respectively. The effects of these associations should be further investigated to help elucidate the modes of action of trace elements and to identify biomarkers, which could ultimately define the optimal intake of these micronutrients at the molecular level. More research must be performed before the roles of these polymorphisms in the serum concentrations of zinc and selenium can be fully understood.
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Affiliation(s)
- Tatiane Jacobsen da Rocha
- Biomedical Health Sciences, University of Health Sciences of Porto Alegre-UFCSPA, Rio Grande do Sul, Brazil.
| | - Camila Korb
- Biomedicine, Institute of Health Sciences, University Feevale, Rio Grande do Sul, Brazil.
| | | | | | - Fabiana Michelsen de Andrade
- Institute of Sciences, Letters and Arts and Institute of Health Sciences, University Feevale, Rio Grande do Sul, Brazil.
| | - Marilu Fiegenbaum
- Department of Basic Health Sciences, UFCSPA, Rio Grande do Sul, Brazil.
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27
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Lasry I, Golan Y, Berman B, Amram N, Glaser F, Assaraf YG. In situ dimerization of multiple wild type and mutant zinc transporters in live cells using bimolecular fluorescence complementation. J Biol Chem 2014; 289:7275-92. [PMID: 24451381 DOI: 10.1074/jbc.m113.533786] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Zinc transporters (ZnTs) facilitate zinc efflux and zinc compartmentalization, thereby playing a key role in multiple physiological processes and pathological disorders, presumed to be modulated by transporter dimerization. We recently proposed that ZnT2 homodimerization is the underlying basis for the dominant negative effect of a novel heterozygous G87R mutation identified in women producing zinc-deficient milk. To provide direct visual evidence for the in situ dimerization and function of multiple normal and mutant ZnTs, we applied here the bimolecular fluorescence complementation (BiFC) technique, which enables direct visualization of specific protein-protein interactions. BiFC is based upon reconstitution of an intact fluorescent protein including YFP when its two complementary, non-fluorescent N- and C-terminal fragments (termed YN and YC) are brought together by a pair of specifically interacting proteins. Homodimerization of ZnT1, -2, -3, -4, and -7 was revealed by high subcellular fluorescence observed upon co-transfection of non-fluorescent ZnT-YC and ZnT-YN; this homodimer fluorescence localized in the characteristic compartments of each ZnT. The validity of the BiFC assay in ZnT dimerization was further corroborated when high fluorescence was obtained upon co-transfection of ZnT5-YC and ZnT6-YN, which are known to form heterodimers. We further show that BiFC recapitulated the pathogenic role that ZnT mutations play in transient neonatal zinc deficiency. Zinquin, a fluorescent zinc probe applied along with BiFC, revealed the in situ functionality of ZnT dimers. Hence, the current BiFC-Zinquin technique provides the first in situ evidence for the dimerization and function of wild type and mutant ZnTs in live cells.
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Affiliation(s)
- Inbal Lasry
- From the Fred Wyszkowski Cancer Research Laboratory, Department of Biology, and
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28
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Haase H, Rink L. Zinc signals and immune function. Biofactors 2014; 40:27-40. [PMID: 23804522 DOI: 10.1002/biof.1114] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/23/2013] [Accepted: 04/25/2013] [Indexed: 12/21/2022]
Abstract
For more than 50 years, it has been known that zinc deficiency compromises immune function. During this time, knowledge about the biochemistry of zinc has continued to grow, but only recent years have provided in-depth molecular insights into the multiple aspects of zinc as a regulator of immunity. A network based on ZnT and ZIP proteins for transport and metallothionein for storage tightly regulates zinc availability, and virtually all aspects of innate and adaptive immunity are affected by zinc. In vivo, zinc deficiency alters the number and function of neutrophil granulocytes, monocytes, natural killer (NK)-, T-, and B-cells. T cell functions and balance between the different subsets are particularly susceptible to changes in zinc status. This article focuses in particular on the main mechanisms by which zinc ions exert essential functions in the immune system. On the one hand, this includes tightly protein bound zinc ions serving catalytic or structural functions in a multitude of different proteins, in particular enzymes and transcription factors. On the other hand, increasing evidence arises for a regulatory role of free zinc ions in signal transduction, especially in cells of the immune system. Identification of several molecular targets, including phosphatases, phosphodiesterases, caspases, and kinases suggest that zinc ions are a second messenger regulating signal transduction in various kinds of immune cells.
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Affiliation(s)
- Hajo Haase
- Institute of Immunology, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, Aachen, Germany
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29
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: transporters. Br J Pharmacol 2013; 170:1706-96. [PMID: 24528242 PMCID: PMC3892292 DOI: 10.1111/bph.12450] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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30
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Árus D, Dancs Á, Nagy NV, Gajda T. A comparative study on the possible zinc binding sites of the human ZnT3 zinc transporter protein. Dalton Trans 2013; 42:12031-40. [PMID: 23839275 DOI: 10.1039/c3dt50754h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The brain specific zinc transporter protein ZnT3 can be related to the amyloid neuropathology of Alzheimer's disease. In order to analyze the metal binding ability of human ZnT3 protein, here we report a potentiometric and solution structural (UV-Vis, CD, EPR, NMR) study of nickel(II), copper(II) and zinc(II) complexes of three peptides mimicking the possible metal binding sequences of this protein. The peptide L¹ (Ac-RHQAGPPHSHR-NH2) is a minimalist, the cyclic peptide L² (cyclo(Ac-CKLHQAGPPHSHGSRGAEYAPLEEGPEEKC-NH2) is a more complete model of the intracellular His-rich loop, which is widely accepted as a putative metal binding site. The peptide L³ (Ac-PFHHCHRD-NH2) is the model of the conserved cytoplasmic N-terminal -HHCH- sequence. In the physiological pH-range, the ZnL¹, ZnH3L² and ZnL³ complexes are the major species in the corresponding binary systems, with {3N(im)}, {3N(im),2/3O(amide)} and {3N(im),S(-)} coordination environments, respectively. The species ZnL³ has 3-4 orders of magnitude higher stability than the other two complexes, indicating the presence of a high-affinity zinc-binding site at the N-terminal tail of the human ZnT3 transporter. Moreover, L³ shows preferred zinc binding as compared to nickel (log β(ZnL³) - log β(NiL³) = 2.3), probably due to the higher preference of zinc(II) for tetrahedral geometry. These facts suggest that zinc binding to the N-terminal -HHCH- sequence of human ZnT3 may be involved in the biological activity of this zinc transporter protein in zinc sensing, binding or translocation processes.
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Affiliation(s)
- Dávid Árus
- Department of Inorganic and Analytical Chemistry, University of Szeged, H-6721 Szeged Dómtér 7, Hungary
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Lambeth JD, Neish AS. Nox enzymes and new thinking on reactive oxygen: a double-edged sword revisited. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2013; 9:119-45. [PMID: 24050626 DOI: 10.1146/annurev-pathol-012513-104651] [Citation(s) in RCA: 338] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Reactive oxygen species (ROS) are a chemical class of molecules that have generally been conceptualized as deleterious entities, albeit ones whose destructive properties could be harnessed as antimicrobial effector functions to benefit the whole organism. This appealingly simplistic notion has been turned on its head in recent years with the discovery of the NADPH oxidases, or Noxes, a family of enzymes dedicated to the production of ROS in a variety of cells and tissues. The Nox-dependent, physiological generation of ROS is highly conserved across virtually all multicellular life, often as a generalized response to microbes and/or other exogenous stressors. This review discusses the current knowledge of the role of physiologically generated ROS and the enzymes that form them in both normal biology and disease.
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Affiliation(s)
- J David Lambeth
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322;
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Itsumura N, Inamo Y, Okazaki F, Teranishi F, Narita H, Kambe T, Kodama H. Compound heterozygous mutations in SLC30A2/ZnT2 results in low milk zinc concentrations: a novel mechanism for zinc deficiency in a breast-fed infant. PLoS One 2013; 8:e64045. [PMID: 23741301 PMCID: PMC3669329 DOI: 10.1371/journal.pone.0064045] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 04/05/2013] [Indexed: 12/16/2022] Open
Abstract
Zinc concentrations in breast milk are considerably higher than those of the maternal serum, to meet the infant's requirements for normal growth and development. Thus, effective mechanisms ensuring secretion of large amounts of zinc into the milk operate in mammary epithelial cells during lactation. ZnT2 was recently found to play an essential role in the secretion of zinc into milk. Heterozygous mutations of human ZnT2 (hZnT2), including H54R and G87R, in mothers result in low (>75% reduction) secretion of zinc into the breast milk, and infants fed on the milk develop transient neonatal zinc deficiency. We identified two novel missense mutations in the SLC30A2/ZnT2 gene in a Japanese mother with low milk zinc concentrations (>90% reduction) whose infant developed severe zinc deficiency; a T to C transition (c.454T>C) at exon 4, which substitutes a tryptophan residue with an arginine residue (W152R), and a C to T transition (c.887C>T) at exon 7, which substitutes a serine residue with a leucine residue (S296L). Biochemical characterization using zinc-sensitive DT40 cells indicated that the W152R mutation abolished the abilities to transport zinc and to form a dimer complex, indicating a loss-of-function mutation. The S296L mutation retained both abilities but was extremely destabilized. The two mutations were found on different alleles, indicating that the genotype of the mother with low milk zinc was compound heterozygous. These results show novel compound heterozygous mutations in the SLC30A2/ZnT2 gene causing zinc deficiency in a breast-fed infant.
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Affiliation(s)
- Naoya Itsumura
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Yasuji Inamo
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Fumiko Okazaki
- Department of Food Science, Kyoto Women's University, Kyoto, Japan
| | - Fumie Teranishi
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Hiroshi Narita
- Department of Food Science, Kyoto Women's University, Kyoto, Japan
| | - Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Hiroko Kodama
- Department of Pediatrics, Teikyo University School of Medicine, Tokyo, Japan
- Department of Health and Dietetics, Faculty of Health and Medical Sciences, Teikyo Heisei University, Tokyo, Japan
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Lasry I, Seo YA, Ityel H, Shalva N, Pode-Shakked B, Glaser F, Berman B, Berezovsky I, Goncearenco A, Klar A, Levy J, Anikster Y, Kelleher SL, Assaraf YG. A dominant negative heterozygous G87R mutation in the zinc transporter, ZnT-2 (SLC30A2), results in transient neonatal zinc deficiency. J Biol Chem 2012; 287:29348-61. [PMID: 22733820 DOI: 10.1074/jbc.m112.368159] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Zinc is an essential mineral, and infants are particularly vulnerable to zinc deficiency as they require large amounts of zinc for their normal growth and development. We have recently described the first loss-of-function mutation (H54R) in the zinc transporter ZnT-2 (SLC30A2) in mothers with infants harboring transient neonatal zinc deficiency (TNZD). Here we identified and characterized a novel heterozygous G87R ZnT-2 mutation in two unrelated Ashkenazi Jewish mothers with infants displaying TNZD. Transient transfection of G87R ZnT-2 resulted in endoplasmic reticulum-Golgi retention, whereas the WT transporter properly localized to intracellular secretory vesicles in HC11 and MCF-7 cells. Consequently, G87R ZnT-2 showed decreased stability compared with WT ZnT-2 as revealed by Western blot analysis. Three-dimensional homology modeling based on the crystal structure of YiiP, a close zinc transporter homologue from Escherichia coli, revealed that the basic arginine residue of the mutant G87R points toward the membrane lipid core, suggesting misfolding and possible loss-of-function. Indeed, functional assays including vesicular zinc accumulation, zinc secretion, and cytoplasmic zinc pool assessment revealed markedly impaired zinc transport in G87R ZnT-2 transfectants. Moreover, co-transfection experiments with both mutant and WT transporters revealed a dominant negative effect of G87R ZnT-2 over the WT ZnT-2; this was associated with mislocalization, decreased stability, and loss of zinc transport activity of the WT ZnT-2 due to homodimerization observed upon immunoprecipitation experiments. These findings establish that inactivating ZnT-2 mutations are an underlying basis of TNZD and provide the first evidence for the dominant inheritance of heterozygous ZnT-2 mutations via negative dominance due to homodimer formation.
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Affiliation(s)
- Inbal Lasry
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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Patrushev N, Seidel-Rogol B, Salazar G. Angiotensin II requires zinc and downregulation of the zinc transporters ZnT3 and ZnT10 to induce senescence of vascular smooth muscle cells. PLoS One 2012; 7:e33211. [PMID: 22427991 PMCID: PMC3299759 DOI: 10.1371/journal.pone.0033211] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 02/11/2012] [Indexed: 12/18/2022] Open
Abstract
Senescence, a hallmark of mammalian aging, is associated with the onset and progression of cardiovascular disease. Angiotensin II (Ang II) signaling and zinc homeostasis dysfunction are increased with age and are linked to cardiovascular disease, but the relationship among these processes has not been investigated. We used a model of cellular senescence induced by Ang II in vascular smooth muscle cells (VSMCs) to explore the role of zinc in vascular dysfunction. We found that Ang II-induced senescence is a zinc-dependent pathway mediated by the downregulation of the zinc transporters ZnT3 and ZnT10, which work to reduce cytosolic zinc. Zinc mimics Ang II by increasing reactive oxygen species (ROS), activating NADPH oxidase activity and Akt, and by downregulating ZnT3 and ZnT10 and inducing senescence. Zinc increases Ang II-induced senescence, while the zinc chelator TPEN, as well as overexpression of ZnT3 or ZnT10, decreases ROS and prevents senescence. Using HEK293 cells, we found that ZnT10 localizes in recycling endosomes and transports zinc into vesicles to prevent zinc toxicity. Zinc and ZnT3/ZnT10 downregulation induces senescence by decreasing the expression of catalase. Consistently, ZnT3 and ZnT10 downregulation by siRNA increases ROS while downregulation of catalase by siRNA induces senescence. Zinc, siZnT3 and siZnT10 downregulate catalase by a post-transcriptional mechanism mediated by decreased phosphorylation of ERK1/2. These data demonstrate that zinc homeostasis dysfunction by decreased expression of ZnT3 or ZnT10 promotes senescence and that Ang II-induced senescence is a zinc and ROS-dependent process. Our studies suggest that zinc might also affect other ROS-dependent processes induced by Ang II, such as hypertrophy and migration of smooth muscle cells.
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Affiliation(s)
| | | | - Gloria Salazar
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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36
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Brast S, Grabner A, Sucic S, Sitte HH, Hermann E, Pavenstädt H, Schlatter E, Ciarimboli G. The cysteines of the extracellular loop are crucial for trafficking of human organic cation transporter 2 to the plasma membrane and are involved in oligomerization. FASEB J 2011; 26:976-86. [PMID: 22085643 DOI: 10.1096/fj.11-180679] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Human organic cation transporter 2 (hOCT2) is involved in transport of many endogenous and exogenous organic cations, mainly in kidney and brain cells. Because the quaternary structure of transmembrane proteins plays an essential role for their cellular trafficking and function, we investigated whether hOCT2 forms oligomeric complexes, and if so, which part of the transporter is involved in the oligomerization. A yeast 2-hybrid mating-based split-ubiquitin system (mbSUS), fluorescence resonance energy transfer, Western blot analysis, cross-linking experiments, immunofluorescence, and uptake measurements of the fluorescent organic cation 4-(4-(dimethylamino)styryl)-N-methylpyridinium were applied to human embryonic kidney 293 (HEK293) cells transfected with hOCT2 and partly also to freshly isolated human proximal tubules. The role of cysteines for oligomerization and trafficking of the transporter to the plasma membranes was investigated in cysteine mutants of hOCT2. hOCT2 formed oligomers both in the HEK293 expression system and in native human kidneys. The cysteines of the large extracellular loop are important to enable correct folding, oligomeric assembly, and plasma membrane insertion of hOCT2. Mutation of the first and the last cysteines of the loop at positions 51 and 143 abolished oligomer formation. Thus, the cysteines of the extracellular loop are important for correct trafficking of the transporter to the plasma membrane and for its oligomerization.
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Affiliation(s)
- Sabine Brast
- Experimentelle Nephrologie, Medizinische Klinik und Poliklinik D, Domagkstrasse 3A, 48149 Münster, Germany
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Sindreu C, Storm DR. Modulation of neuronal signal transduction and memory formation by synaptic zinc. Front Behav Neurosci 2011; 5:68. [PMID: 22084630 PMCID: PMC3211062 DOI: 10.3389/fnbeh.2011.00068] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 10/03/2011] [Indexed: 12/31/2022] Open
Abstract
The physiological role of synaptic zinc has remained largely enigmatic since its initial detection in hippocampal mossy fibers over 50 years ago. The past few years have witnessed a number of studies highlighting the ability of zinc ions to regulate ion channels and intracellular signaling pathways implicated in neuroplasticity, and others that shed some light on the elusive role of synaptic zinc in learning and memory. Recent behavioral studies using knock-out mice for the synapse-specific zinc transporter ZnT-3 indicate that vesicular zinc is required for the formation of memories dependent on the hippocampus and the amygdala, two brain centers that are prominently innervated by zinc-rich fibers. A common theme emerging from this research is the activity-dependent regulation of the Erk1/2 mitogen-activated-protein kinase pathway by synaptic zinc through diverse mechanisms in neurons. Here we discuss current knowledge on how synaptic zinc may play a role in cognition through its impact on neuronal signaling.
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Affiliation(s)
- Carlos Sindreu
- Department of Pharmacology, University of Washington Seattle, WA, USA
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Smidt K, Rungby J. ZnT3: a zinc transporter active in several organs. Biometals 2011; 25:1-8. [DOI: 10.1007/s10534-011-9490-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 08/17/2011] [Indexed: 12/30/2022]
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Fukada T, Kambe T. Molecular and genetic features of zinc transporters in physiology and pathogenesis. Metallomics 2011; 3:662-74. [PMID: 21566827 DOI: 10.1039/c1mt00011j] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Zinc (Zn) is a vital element. It plays indispensable roles in multifarious cellular processes, affecting the expression and activity of a variety of molecules, including transcription factors, enzymes, adapters, channels, growth factors, and their receptors. A disturbance in Zn homeostasis due to Zn deficiency or an excess of Zn absorption can therefore impair the cellular machinery and exert various influences on physiological programs, such as systemic growth, morphogenetic processes, and immune responses, as well as neuro-sensory and endocrine functions. Thus, Zn imbalance becomes pathogenic in humans. Zn homeostasis is controlled by the coordinated actions of Zn transporters, which are responsible for Zn influx and efflux, and intricately regulate the intracellular and extracellular Zn concentration and distribution. In this review, we describe crucial roles of Zn transporters in biological phenomena, focusing in particular on how Zn transporters contribute to cellular events at the molecular, biochemical, and genetic level, with recent progress uncovering the roles of Zn transporters in physiology and pathogenesis.
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Affiliation(s)
- Toshiyuki Fukada
- Laboratory for Cytokine Signaling, RIKEN Research Center for Allergy and Immunology, Yokohama, Japan.
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40
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Fukunaka A, Kurokawa Y, Teranishi F, Sekler I, Oda K, Ackland ML, Faundez V, Hiromura M, Masuda S, Nagao M, Enomoto S, Kambe T. Tissue nonspecific alkaline phosphatase is activated via a two-step mechanism by zinc transport complexes in the early secretory pathway. J Biol Chem 2011; 286:16363-73. [PMID: 21402707 DOI: 10.1074/jbc.m111.227173] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A number of enzymes become functional by binding to zinc during their journey through the early secretory pathway. The zinc transporters (ZnTs) located there play important roles in this step. We have previously shown that two zinc transport complexes, ZnT5/ZnT6 heterodimers and ZnT7 homo-oligomers, are required for the activation of alkaline phosphatases, by converting them from the apo- to the holo-form. Here, we investigated the molecular mechanisms of this activation. ZnT1 and ZnT4 expressed in chicken DT40 cells did not contribute to the activation of tissue nonspecific alkaline phosphatase (TNAP). The reduced activity of TNAP in DT40 cells deficient in both ZnT complexes was not restored by zinc supplementation nor by exogenous expression of other ZnTs that increase the zinc content in the secretory pathway. Moreover, we showed that expression of ZnT5/ZnT6 heterodimers reconstituted with zinc transport-incompetent ZnT5 mutant failed to restore TNAP activity but could stabilize the TNAP protein as the apo-form, regardless of zinc status. These findings demonstrate that TNAP is activated not simply by passive zinc binding but by an elaborate two-step mechanism via protein stabilization followed by enzyme conversion from the apo- to the holo-form with zinc loaded by ZnT complexes in the early secretory pathway.
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Affiliation(s)
- Ayako Fukunaka
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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Shchepin R, Möller MN, Kim HYH, Hatch DM, Bartesaghi S, Kalyanaraman B, Radi R, Porter NA. Tyrosine-lipid peroxide adducts from radical termination: para coupling and intramolecular Diels-Alder cyclization. J Am Chem Soc 2010; 132:17490-500. [PMID: 21090613 PMCID: PMC3677824 DOI: 10.1021/ja106503a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Free radical co-oxidation of polyunsaturated lipids with tyrosine or phenolic analogues of tyrosine gave rise to lipid peroxide-tyrosine (phenol) adducts in both aqueous micellar and organic solutions. The novel adducts were isolated and characterized by 1D and 2D NMR spectroscopy as well as by mass spectrometry (MS). The spectral data suggest that the polyunsaturated lipid peroxyl radicals give stable peroxide coupling products exclusively at the para position of the tyrosyl (phenoxy) radicals. These adducts have characteristic (13)C chemical shifts at 185 ppm due to the cross-conjugated carbonyl of the phenol-derived cyclohexadienone. The primary peroxide adducts subsequently undergo intramolecular Diels-Alder (IMDA) cyclization, affording a number of diastereomeric tricyclic adducts that have characteristic carbonyl (13)C chemical shifts at ~198 ppm. All of the NMR HMBC and HSQC correlations support the structure assignments of the primary and Diels-Alder adducts, as does MS collision-induced dissociation data. Kinetic rate constants and activation parameters for the IMDA reaction were determined, and the primary adducts were reduced with cuprous ion to give a phenol-derived 4-hydroxycyclohexa-2,5-dienone. No products from adduction of peroxyls at the phenolic ortho position were found in either the primary or cuprous reduction product mixtures. These studies provide a framework for understanding the nature of lipid-protein adducts formed by peroxyl-tyrosyl radical-radical termination processes. Coupling of lipid peroxyl radicals with tyrosyl radicals leads to cyclohexenone and cyclohexadienone adducts, which are of interest in and of themselves since, as electrophiles, they are likely targets for protein nucleophiles. One consequence of lipid peroxyl reactions with tyrosyls may therefore be protein-protein cross-links via interprotein Michael adducts.
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Affiliation(s)
- Roman Shchepin
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, USA
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Aguirre J, Lambeth JD. Nox enzymes from fungus to fly to fish and what they tell us about Nox function in mammals. Free Radic Biol Med 2010; 49:1342-53. [PMID: 20696238 PMCID: PMC2981133 DOI: 10.1016/j.freeradbiomed.2010.07.027] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 07/27/2010] [Accepted: 07/30/2010] [Indexed: 01/09/2023]
Abstract
The production of reactive oxygen species (ROS) in a highly regulated fashion is a hallmark of members of the NADPH oxidase (Nox) family of enzymes. Nox enzymes are present in most eukaryotic groups such as the amebozoid, fungi, algae and plants, and animals, in which they are involved in seemingly diverse biological processes. However, a comprehensive survey of Nox functions throughout biology reveals common functional themes. Noxes are often activated in response to stressful conditions such as nutrient starvation, physical damage, or pathogen attack. Although the end result varies depending on the organism and tissue, Nox-produced ROS mediate the response to the adverse stimuli, such as innate immunity responses in plants and animals or cell differentiation in Dictyostelium, fungi, and plants. These responses involve ROS-mediated signaling mechanisms occurring at intracellular or cell-to-cell levels and sometimes involve cell wall or extracellular matrix cross-linking. Indeed, Noxes are involved in local and systemic signaling from plants to fish and in cross-linking of the plant hair-cell wall, synthesis of the nematode cuticle, and formation of the sea urchin fertilization envelope. The extensive use of Nox enzymes in biology to regulate cell-to-cell signaling and morphogenesis suggests that additional functions in mammalian signaling and development remain to be discovered.
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Affiliation(s)
- Jesús Aguirre
- Instituto de Fisiología Celular, Departamento de Biologia Celular y Desarrollo, Universidad Nacional Autónoma de México, México DF 04510, México
| | - J. David Lambeth
- Department of Pathology and Laboratory Medicine, Emory University Medical School, Atlanta, GA, 30322, USA
- Corresponding Author: Department of Pathology and Laboratory Medicine, Emory University Medical School, Atlanta, GA, 30322.
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Brender JR, Hartman K, Nanga RPR, Popovych N, de la Salud Bea R, Vivekanandan S, Marsh ENG, Ramamoorthy A. Role of zinc in human islet amyloid polypeptide aggregation. J Am Chem Soc 2010; 132:8973-83. [PMID: 20536124 PMCID: PMC2904811 DOI: 10.1021/ja1007867] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Human Islet Amyloid Polypeptide (hIAPP) is a highly amyloidogenic protein found in islet cells of patients with type II diabetes. Because hIAPP is highly toxic to beta-cells under certain conditions, it has been proposed that hIAPP is linked to the loss of beta-cells and insulin secretion in type II diabetics. One of the interesting questions surrounding this peptide is how the toxic and aggregation prone hIAPP peptide can be maintained in a safe state at the high concentrations that are found in the secretory granule where it is stored. We show here zinc, which is found at millimolar concentrations in the secretory granule, significantly inhibits hIAPP amyloid fibrillogenesis at concentrations similar to those found in the extracellular environment. Zinc has a dual effect on hIAPP fibrillogenesis: it increases the lag-time for fiber formation and decreases the rate of addition of hIAPP to existing fibers at lower concentrations, while having the opposite effect at higher concentrations. Experiments at an acidic pH which partially neutralizes the change in charge upon zinc binding show inhibition is largely due to an electrostatic effect at His18. High-resolution structures of hIAPP determined from NMR experiments confirm zinc binding to His18 and indicate zinc induces localized disruption of the secondary structure of IAPP in the vicinity of His18 of a putative helical intermediate of IAPP. The inhibition of the formation of aggregated and toxic forms of hIAPP by zinc provides a possible mechanism between the recent discovery of linkage between deleterious mutations in the SLC30A8 zinc transporter, which transports zinc into the secretory granule, and type II diabetes.
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Affiliation(s)
- Jeffrey R. Brender
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Kevin Hartman
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | | | - Natalya Popovych
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Roberto de la Salud Bea
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Subramanian Vivekanandan
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - E. Neil G. Marsh
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109-1055, USA
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