1
|
Holtzen SE, Rakshit A, Palmer AE. Protocol for measuring labile cytosolic Zn 2+ using an in situ calibration of a genetically encoded FRET sensor. STAR Protoc 2024; 5:103130. [PMID: 38870018 PMCID: PMC11225890 DOI: 10.1016/j.xpro.2024.103130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/15/2024] [Accepted: 05/24/2024] [Indexed: 06/15/2024] Open
Abstract
Zinc (Zn2+) plays roles in structure, catalysis, and signaling. The majority of cellular Zn2+ is bound by proteins, but a fraction of total Zn2+ exists in a labile form. Here, we present a protocol for measuring labile cytosolic Zn2+ using an in situ calibration of a genetically encoded Förster resonance energy transfer (FRET) sensor. We describe steps for producing buffered Zn2+ solutions for performing an imaging-based calibration and analyzing the imaging data generated to determine labile Zn2+ concentration in single cells. For complete details on the use and execution of this protocol, please refer to Rakshit and Holtzen et al.1.
Collapse
Affiliation(s)
- Samuel E Holtzen
- BioFrontiers Institute and Department of Biochemistry, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA; Department of Molecular Cellular Developmental Biology and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Ananya Rakshit
- BioFrontiers Institute and Department of Biochemistry, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Amy E Palmer
- BioFrontiers Institute and Department of Biochemistry, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA.
| |
Collapse
|
2
|
Hario S, Le GNT, Sugimoto H, Takahashi-Yamashiro K, Nishinami S, Toda H, Li S, Marvin JS, Kuroda S, Drobizhev M, Terai T, Nasu Y, Campbell RE. High-Performance Genetically Encoded Green Fluorescent Biosensors for Intracellular l-Lactate. ACS CENTRAL SCIENCE 2024; 10:402-416. [PMID: 38435524 PMCID: PMC10906044 DOI: 10.1021/acscentsci.3c01250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/31/2023] [Accepted: 01/04/2024] [Indexed: 03/05/2024]
Abstract
l-Lactate is a monocarboxylate produced during the process of cellular glycolysis and has long generally been considered a waste product. However, studies in recent decades have provided new perspectives on the physiological roles of l-lactate as a major energy substrate and a signaling molecule. To enable further investigations of the physiological roles of l-lactate, we have developed a series of high-performance (ΔF/F = 15 to 30 in vitro), intensiometric, genetically encoded green fluorescent protein (GFP)-based intracellular l-lactate biosensors with a range of affinities. We evaluated these biosensors in cultured cells and demonstrated their application in an ex vivo preparation of Drosophila brain tissue. Using these biosensors, we were able to detect glycolytic oscillations, which we analyzed and mathematically modeled.
Collapse
Affiliation(s)
- Saaya Hario
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Giang N. T. Le
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Hikaru Sugimoto
- Department
of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kei Takahashi-Yamashiro
- Department
of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department
of Chemistry, Faculty of Science, University
of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Suguru Nishinami
- International
Institute for Integrative Sleep Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Hirofumi Toda
- International
Institute for Integrative Sleep Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Selene Li
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Jonathan S. Marvin
- Howard
Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia 20147, United States
| | - Shinya Kuroda
- Department
of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Mikhail Drobizhev
- Department
of Microbiology and Cell Biology, Montana
State University, Bozeman, Montana 59717, United States
| | - Takuya Terai
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yusuke Nasu
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- PRESTO,
Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Robert E. Campbell
- Department
of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department
of Chemistry, Faculty of Science, University
of Alberta, Edmonton, Alberta T6G 2G2, Canada
- CERVO
Brain Research Center and Department of Biochemistry, Microbiology,
and Bioinformatics, Université Laval, Québec, Québec G1 V 0A6, Canada
| |
Collapse
|
3
|
Rakshit A, Holtzen SE, Lo MN, Conway KA, Palmer AE. Human cells experience a Zn 2+ pulse in early G1. Cell Rep 2023; 42:112656. [PMID: 37330912 PMCID: PMC10592493 DOI: 10.1016/j.celrep.2023.112656] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/07/2023] [Accepted: 05/31/2023] [Indexed: 06/20/2023] Open
Abstract
Zinc is an essential micronutrient required for all domains of life. Cells maintain zinc homeostasis using a network of transporters, buffers, and transcription factors. Zinc is required for mammalian cell proliferation, and zinc homeostasis is remodeled during the cell cycle, but whether labile zinc changes in naturally cycling cells has not been established. We use genetically encoded fluorescent reporters, long-term time-lapse imaging, and computational tools to track labile zinc over the cell cycle in response to changes in growth media zinc and knockdown of the zinc-regulatory transcription factor MTF-1. Cells experience a pulse of labile zinc in early G1, whose magnitude varies with zinc in growth media. Knockdown of MTF-1 increases labile zinc and the zinc pulse. Our results suggest that cells need a minimum zinc pulse to proliferate and that if labile zinc levels are too high, cells pause proliferation until labile cellular zinc is lowered.
Collapse
Affiliation(s)
- Ananya Rakshit
- Department of Biochemistry and BioFrontiers Institute, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Samuel E Holtzen
- Department of Molecular Cellular Developmental Biology and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Maria N Lo
- Department of Biochemistry and BioFrontiers Institute, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Kylie A Conway
- Department of Biochemistry and BioFrontiers Institute, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Amy E Palmer
- Department of Biochemistry and BioFrontiers Institute, 3415 Colorado Avenue, University of Colorado Boulder, Boulder, CO 80303, USA.
| |
Collapse
|
4
|
Dejima K, Imae R, Suehiro Y, Yoshida K, Mitani S. An endomembrane zinc transporter negatively regulates systemic RNAi in Caenorhabditis elegans. iScience 2023; 26:106930. [PMID: 37305693 PMCID: PMC10250833 DOI: 10.1016/j.isci.2023.106930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/18/2023] [Accepted: 05/16/2023] [Indexed: 06/13/2023] Open
Abstract
Double-stranded RNA (dsRNA) regulates gene expression in a sequence-dependent manner. In Caenorhabditis elegans, dsRNA spreads through the body and leads to systemic RNA silencing. Although several genes involved in systemic RNAi have been genetically identified, molecules that mediate systemic RNAi remain largely unknown. Here, we identified ZIPT-9, a C. elegans homolog of ZIP9/SLC39A9, as a broad-spectrum negative regulator of systemic RNAi. We showed that RSD-3, SID-3, and SID-5 genetically act in parallel for efficient RNAi, and that zipt-9 mutants suppress the RNAi defects of all the mutants. Analysis of a complete set of deletion mutants for SLC30 and SLC39 family genes revealed that only zipt-9 mutants showed altered RNAi activity. Based on these results and our analysis using transgenic Zn2+ reporters, we propose that ZIPT-9-dependent Zn2+ homeostasis, rather than overall cytosolic Zn2+, modulates systemic RNAi activity. Our findings reveal a previously unknown function of zinc transporters in negative RNAi regulation.
Collapse
Affiliation(s)
- Katsufumi Dejima
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Rieko Imae
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Yuji Suehiro
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Keita Yoshida
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, 8-1, Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| |
Collapse
|
5
|
Torres-Ocampo AP, Palmer AE. Genetically encoded fluorescent sensors for metals in biology. Curr Opin Chem Biol 2023; 74:102284. [PMID: 36917910 PMCID: PMC10573084 DOI: 10.1016/j.cbpa.2023.102284] [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: 11/01/2022] [Revised: 01/30/2023] [Accepted: 02/10/2023] [Indexed: 03/14/2023]
Abstract
Metal ions intersect a wide range of biological processes. Some metal ions are essential and hence absolutely required for the growth and health of an organism, others are toxic and there is great interest in understanding mechanisms of toxicity. Genetically encoded fluorescent sensors are powerful tools that enable the visualization, quantification, and tracking of dynamics of metal ions in biological systems. Here, we review recent advances in the development of genetically encoded fluorescent sensors for metal ions. We broadly focus on 5 classes of sensors: single fluorescent protein, FRET-based, chemigenetic, DNAzymes, and RNA-based. We highlight recent developments in the past few years and where these developments stand concerning the rest of the field.
Collapse
Affiliation(s)
- Ana P Torres-Ocampo
- BioFrontiers Institute, University of Colorado, Boulder, 3415 Colorado Ave, CO, 80303, Boulder, United States
| | - Amy E Palmer
- Department of Biochemistry, University of Colorado, Boulder, 3415 Colorado Ave, CO, 80303, Boulder, United States; BioFrontiers Institute, University of Colorado, Boulder, 3415 Colorado Ave, CO, 80303, Boulder, United States.
| |
Collapse
|
6
|
Park J, Cleary MB, Li D, Mattocks JA, Xu J, Wang H, Mukhopadhyay S, Gale EM, Cotruvo JA. A genetically encoded fluorescent sensor for manganese(II), engineered from lanmodulin. Proc Natl Acad Sci U S A 2022; 119:e2212723119. [PMID: 36508659 PMCID: PMC9907080 DOI: 10.1073/pnas.2212723119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/10/2022] [Indexed: 12/15/2022] Open
Abstract
The design of selective metal-binding sites is a challenge in both small-molecule and macromolecular chemistry. Selective recognition of manganese (II)-the first-row transition metal ion that tends to bind with the lowest affinity to ligands, as described by the Irving-Williams series-is particularly difficult. As a result, there is a dearth of chemical biology tools with which to study manganese physiology in live cells, which would advance understanding of photosynthesis, host-pathogen interactions, and neurobiology. Here we report the rational re-engineering of the lanthanide-binding protein, lanmodulin, into genetically encoded fluorescent sensors for MnII, MnLaMP1 and MnLaMP2. These sensors with effective Kd(MnII) of 29 and 7 µM, respectively, defy the Irving-Williams series to selectively detect MnII in vitro and in vivo. We apply both sensors to visualize kinetics of bacterial labile manganese pools. Biophysical studies indicate the importance of coordinated solvent and hydrophobic interactions in the sensors' selectivity. Our results establish lanmodulin as a versatile scaffold for design of selective protein-based biosensors and chelators for metals beyond the f-block.
Collapse
Affiliation(s)
- Jennifer Park
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| | - Michael B. Cleary
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital / Harvard Medical School, Charlestown, MA02129
| | - Danyang Li
- Division of Pharmacology and Toxicology, College of Pharmacy, Institute for Cellular and Molecular Biology, and Institute for Neuroscience, The University of Texas at Austin, Austin, TX78712
| | - Joseph A. Mattocks
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| | - Jiansong Xu
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| | - Huan Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital / Harvard Medical School, Charlestown, MA02129
| | - Somshuvra Mukhopadhyay
- Division of Pharmacology and Toxicology, College of Pharmacy, Institute for Cellular and Molecular Biology, and Institute for Neuroscience, The University of Texas at Austin, Austin, TX78712
| | - Eric M. Gale
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital / Harvard Medical School, Charlestown, MA02129
| | - Joseph A. Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| |
Collapse
|
7
|
Zhang C, Dischler A, Glover K, Qin Y. Neuronal signalling of zinc: from detection and modulation to function. Open Biol 2022; 12:220188. [PMID: 36067793 PMCID: PMC9448499 DOI: 10.1098/rsob.220188] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Zinc is an essential trace element that stabilizes protein structures and allosterically modulates a plethora of enzymes, ion channels and neurotransmitter receptors. Labile zinc (Zn2+) acts as an intracellular and intercellular signalling molecule in response to various stimuli, which is especially important in the central nervous system. Zincergic neurons, characterized by Zn2+ deposits in synaptic vesicles and presynaptic Zn2+ release, are found in the cortex, hippocampus, amygdala, olfactory bulb and spinal cord. To provide an overview of synaptic Zn2+ and intracellular Zn2+ signalling in neurons, the present paper summarizes the fluorescent sensors used to detect Zn2+ signals, the cellular mechanisms regulating the generation and buffering of Zn2+ signals, as well as the current perspectives on their pleiotropic effects on phosphorylation signalling, synapse formation, synaptic plasticity, as well as sensory and cognitive function.
Collapse
Affiliation(s)
- Chen Zhang
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
| | - Anna Dischler
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
| | - Kaitlyn Glover
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
| | - Yan Qin
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
| |
Collapse
|
8
|
Chen YY, O'Halloran TV. A zinc chaperone mediates the flow of an inorganic commodity to an important cellular client. Cell 2022; 185:2013-2015. [PMID: 35688131 DOI: 10.1016/j.cell.2022.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 01/27/2023]
Abstract
Zinc is an essential element in living organisms, yet little is known about how cells ensure that zinc is allocated to the correct metalloproteins. Papers in Cell and Cell Reports demonstrate that the ZNG1 family of GTPases have metallochaperone functions: they directly transfer zinc to, and thereby activate, methionine aminopeptidases that are crucial for protein modification during or after translation.
Collapse
Affiliation(s)
- Yu-Ying Chen
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Thomas V O'Halloran
- Department of Microbiology and Molecular Genetics, Department of Chemistry, and Elemental Health Institute, Michigan State University, East Lansing, MI 48824, USA.
| |
Collapse
|
9
|
Stanton C, Sanders D, Krämer U, Podar D. Zinc in plants: Integrating homeostasis and biofortification. MOLECULAR PLANT 2022; 15:65-85. [PMID: 34952215 DOI: 10.1016/j.molp.2021.12.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/07/2021] [Accepted: 12/21/2021] [Indexed: 05/24/2023]
Abstract
Zinc plays many essential roles in life. As a strong Lewis acid that lacks redox activity under environmental and cellular conditions, the Zn2+ cation is central in determining protein structure and catalytic function of nearly 10% of most eukaryotic proteomes. While specific functions of zinc have been elucidated at a molecular level in a number of plant proteins, wider issues abound with respect to the acquisition and distribution of zinc by plants. An important challenge is to understand how plants balance between Zn supply in soil and their own nutritional requirement for zinc, particularly where edaphic factors lead to a lack of bioavailable zinc or, conversely, an excess of zinc that bears a major risk of phytotoxicity. Plants are the ultimate source of zinc in the human diet, and human Zn deficiency accounts for over 400 000 deaths annually. Here, we review the current understanding of zinc homeostasis in plants from the molecular and physiological perspectives. We provide an overview of approaches pursued so far in Zn biofortification of crops. Finally, we outline a "push-pull" model of zinc nutrition in plants as a simplifying concept. In summary, this review discusses avenues that can potentially deliver wider benefits for both plant and human Zn nutrition.
Collapse
Affiliation(s)
| | - Dale Sanders
- John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK
| | - Ute Krämer
- Molecular Genetics and Physiology of Plants, Ruhr University Bochum, 44801 Bochum, Germany.
| | - Dorina Podar
- Department of Molecular Biology and Biotechnology and Centre for Systems Biology, Biodiversity and Bioresources, Babes-Bolyai University, 400084 Cluj-Napoca, Romania.
| |
Collapse
|
10
|
Kowada T, Mizukami S. Fluorescent Probes for the Quantification of Labile Metal Ions in Living Cells. J SYN ORG CHEM JPN 2021. [DOI: 10.5059/yukigoseikyokaishi.79.1020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Shin Mizukami
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
| |
Collapse
|
11
|
Janiszewski LN, Minson M, Allen MA, Dowell RD, Palmer AE. Characterization of Global Gene Expression, Regulation of Metal Ions, and Infection Outcomes in Immune-Competent 129S6 Mouse Macrophages. Infect Immun 2021; 89:e0027321. [PMID: 34370511 PMCID: PMC8519282 DOI: 10.1128/iai.00273-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/27/2021] [Indexed: 11/20/2022] Open
Abstract
Nutritional immunity involves cellular and physiological responses to invading pathogens, such as limiting iron, increasing exposure to bactericidal copper, and altering zinc to restrict the growth of pathogens. Here, we examine infection of bone marrow-derived macrophages from 129S6/SvEvTac mice by Salmonella enterica serovar Typhimurium. The 129S6/SvEvTac mice possess a functional Slc11a1 (Nramp-1), a phagosomal transporter of divalent cations that plays an important role in modulating metal availability to the pathogen. We carried out global RNA sequencing upon treatment with live or heat-killed Salmonella at 2 h and 18 h postinfection and observed widespread changes in metal transport, metal-dependent genes, and metal homeostasis genes, suggesting significant remodeling of iron, copper, and zinc availability by host cells. Changes in host cell gene expression suggest infection increases cytosolic zinc while simultaneously limiting zinc within the phagosome. Using a genetically encoded sensor, we demonstrate that cytosolic labile zinc increases 45-fold at 12 h postinfection. Further, manipulation of zinc in the medium alters bacterial clearance and replication, with zinc depletion inhibiting both processes. Comparing the transcriptomic changes to published data on infection of C57BL/6 macrophages revealed notable differences in metal regulation and the global immune response. Our results reveal that 129S6 macrophages represent a distinct model system compared to C57BL/6 macrophages. Further, our results indicate that manipulation of zinc at the host-pathogen interface is more nuanced than that of iron or copper. The 129S6 macrophages leverage intricate means of manipulating zinc availability and distribution to limit the pathogen's access to zinc, while simultaneously ensuring sufficient zinc to support the immune response.
Collapse
Affiliation(s)
- Lara N. Janiszewski
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
- Department of Molecular Cellular Developmental Biology and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| | - Michael Minson
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| | - Mary A. Allen
- Department of Molecular Cellular Developmental Biology and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| | - Robin D. Dowell
- Department of Molecular Cellular Developmental Biology and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| | - Amy E. Palmer
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| |
Collapse
|
12
|
Si D, Nie G, Hurst TK, Fierke CA, Kopelman R. Combining Active Carbonic Anhydrase with Nanogels: Enzyme Protection and Zinc Sensing. Int J Nanomedicine 2021; 16:6645-6660. [PMID: 34611401 PMCID: PMC8486011 DOI: 10.2147/ijn.s321099] [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: 06/22/2021] [Accepted: 09/03/2021] [Indexed: 11/23/2022] Open
Abstract
Background Due to its excellent biocompatibility, the polyacrylamide (PAAm) hydrogel has shown great potential for the immobilization of enzymes used in biomedical applications. The major challenge involved is to preserve, during the immobilization process, both the biological activity and the structural integrity of the enzymes. Here we report, for the first time, a proof-of-concept study for embedding active carbonic anhydrase (CA) into polyacrylamide (PAAm) nanogels. By immobilizing CA in these nanogels, we hope to provide important advantages, such as matrix protection of the CA as well as its targeted delivery, and also for potentially using these nanogels as zinc nano-biosensors, both in-vitro and in-vivo. Methods and Results Two methods are reported here for CA immobilization: encapsulation and surface conjugation. In the encapsulation method, the common process was improved, so as to best preserve the CA, by 1) using a novel biofriendly nonionic surfactant system (Span 80/Tween 80/Brij 30) and 2) using an Al2O3 adsorptive filtration purification procedure. In the surface conjugation method, blank PAAm nanogels were activated by N-hydroxysuccinimide and the CA was cross-linked to the nanogels. The amount of active CA immobilized in the nanoparticles was quantified for both methods. Per 1 g nanogels, the CA encapsulated nanogels contain 11.3 mg active CA, while the CA conjugated nanogels contain 22.5 mg active CA. Also, the CA conjugated nanoparticles successfully measured free Zn2+ levels in solution, with the Zn2+ dissociation constant determined to be 9 pM. Conclusion This work demonstrates universal methods for immobilizing highly fragile bio-macromolecules inside nanoparticle carriers, while preserving their structural integrity and biological activity. The advantages and limitations are discussed, as well as the potential biomedical applications.
Collapse
Affiliation(s)
- Di Si
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Guochao Nie
- School of Physics and Telecommunication Engineering, Yulin Normal University, Yulin, People's Republic of China.,China-Ukraine Joint Research Center for Nano Carbon Black, Yulin, People's Republic of China.,Guangxi Key Laboratory of Agricultural Resources Chemistry and Biotechnology, Yulin, People's Republic of China
| | - Tamiika K Hurst
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Carol A Fierke
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Raoul Kopelman
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
13
|
Abstract
Zinc (Zn2+) is an essential metal in biology, and its bioavailability is highly regulated. Many cell types exhibit fluctuations in Zn2+ that appear to play an important role in cellular function. However, the detailed molecular mechanisms by which Zn2+ dynamics influence cell physiology remain enigmatic. Here, we use a combination of fluorescent biosensors and cell perturbations to define how changes in intracellular Zn2+ impact kinase signaling pathways. By simultaneously monitoring Zn2+ dynamics and kinase activity in individual cells, we quantify changes in labile Zn2+ and directly correlate changes in Zn2+ with ERK and Akt activity. Under our experimental conditions, Zn2+ fluctuations are not toxic and do not activate stress-dependent kinase signaling. We demonstrate that while Zn2+ can nonspecifically inhibit phosphatases leading to sustained kinase activation, ERK and Akt are predominantly activated via upstream signaling and through a common node via Ras. We provide a framework for quantification of Zn2+ fluctuations and correlate these fluctuations with signaling events in single cells to shed light on the role that Zn2+ dynamics play in healthy cell signaling.
Collapse
|
14
|
Ghazvini Zadeh EH, Huang Z, Xia J, Li D, Davidson HW, Li WH. ZIGIR, a Granule-Specific Zn 2+ Indicator, Reveals Human Islet α Cell Heterogeneity. Cell Rep 2021; 32:107904. [PMID: 32668245 DOI: 10.1016/j.celrep.2020.107904] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/04/2020] [Accepted: 06/23/2020] [Indexed: 02/07/2023] Open
Abstract
Numerous mammalian cells contain abundant Zn2+ in their secretory granules, yet available Zn2+ sensors lack the desired specificity and sensitivity for imaging granular Zn2+. We developed a fluorescent zinc granule indicator, ZIGIR, that possesses numerous desired properties for live cell imaging, including >100-fold fluorescence enhancement, membrane permeability, and selective enrichment to acidic granules. The combined advantages endow ZIGIR with superior sensitivity and specificity for imaging granular Zn2+. ZIGIR enables separation of heterogenous β cells based on their insulin content and sorting of mouse islets into pure α cells and β cells. In human islets, ZIGIR facilitates sorting of endocrine cells into highly enriched α cells and β cells, reveals unexpectedly high Zn2+ activity in the somatostatin granule of some δ cells, and uncovers variation in the glucagon content among human α cells. We expect broad applications of ZIGIR for studying Zn2+ biology and Zn2+-rich secretory granules and for engineering β cells with high insulin content for treating diabetes.
Collapse
Affiliation(s)
- Ebrahim H Ghazvini Zadeh
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - ZhiJiang Huang
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - Jing Xia
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA; Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Daliang Li
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - Howard W Davidson
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Wen-Hong Li
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA.
| |
Collapse
|
15
|
Kowada T, Watanabe T, Amagai Y, Liu R, Yamada M, Takahashi H, Matsui T, Inaba K, Mizukami S. Quantitative Imaging of Labile Zn 2+ in the Golgi Apparatus Using a Localizable Small-Molecule Fluorescent Probe. Cell Chem Biol 2020; 27:1521-1531.e8. [PMID: 32997976 DOI: 10.1016/j.chembiol.2020.09.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 06/16/2020] [Accepted: 09/08/2020] [Indexed: 12/15/2022]
Abstract
Fluorescent Zn2+ probes used for the quantitative analysis of labile Zn2+ concentration ([Zn2+]) in target organelles are crucial for understanding the role of Zn2+ in biological processes. Although several fluorescent Zn2+ probes have been developed to date, there is still a lack of consensus concerning the [Zn2+] in intracellular organelles. In this study, we describe the development of ZnDA-1H, a small-molecule fluorescent probe for Zn2+, which exhibits less pH sensitivity, high Zn2+ selectivity, and large fluorescence enhancement upon binding to Zn2+. Through protein labeling technology, ZnDA-1H was precisely targeted in various intracellular organelles, such as the nucleus, mitochondria, endoplasmic reticulum, and Golgi apparatus. ZnDA-1H exhibited a reversible fluorescence response toward labile Zn2+ in these organelles in live cells. Using this probe, the [Zn2+] in the Golgi apparatus was estimated to be 25 ± 1 nM, suggesting that labile Zn2+ plays a physiological role in the secretory pathway.
Collapse
Affiliation(s)
- Toshiyuki Kowada
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Tomomi Watanabe
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Yuta Amagai
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Rong Liu
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Momo Yamada
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Hiroto Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Shin Mizukami
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan.
| |
Collapse
|
16
|
Pratt EPS, Damon LJ, Anson KJ, Palmer AE. Tools and techniques for illuminating the cell biology of zinc. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118865. [PMID: 32980354 DOI: 10.1016/j.bbamcr.2020.118865] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 12/19/2022]
Abstract
Zinc (Zn2+) is an essential micronutrient that is required for a wide variety of cellular processes. Tools and methods have been instrumental in revealing the myriad roles of Zn2+ in cells. This review highlights recent developments fluorescent sensors to measure the labile Zn2+ pool, chelators to manipulate Zn2+ availability, and fluorescent tools and proteomics approaches for monitoring Zn2+-binding proteins in cells. Finally, we close with some highlights on the role of Zn2+ in regulating cell function and in cell signaling.
Collapse
Affiliation(s)
- Evan P S Pratt
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave, Boulder, CO 80303, United States of America
| | - Leah J Damon
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave, Boulder, CO 80303, United States of America
| | - Kelsie J Anson
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave, Boulder, CO 80303, United States of America
| | - Amy E Palmer
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave, Boulder, CO 80303, United States of America.
| |
Collapse
|
17
|
Huey J, Keutler K, Schultz C. Chemical Biology Toolbox for Studying Pancreatic Islet Function - A Perspective. Cell Chem Biol 2020; 27:1015-1031. [PMID: 32822616 DOI: 10.1016/j.chembiol.2020.07.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/10/2020] [Accepted: 07/28/2020] [Indexed: 01/14/2023]
Abstract
The islets of Langerhans represent one of the many complex endocrine organs in mammals. Traditionally, islet function is studied by a mixture of physiological, cell biological, and molecular biological methods. Recently, novel techniques stemming from the ever-increasing toolbox provided by chemical laboratories have been added to the repertoire. Many emerging techniques will soon be available to manipulate and monitor islet function at the single-cell level and potentially in intact model animals, as well as in isolated human islets. Here, we review the most current small-molecule-based and genetically encoded molecular tool sets available to study islet function. We provide an outlook regarding future tool developments that will impact islet research, with a special focus on the interplay between different islet cell types.
Collapse
Affiliation(s)
- Julia Huey
- Program in Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97210, USA; Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA
| | - Kaya Keutler
- Program in Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97210, USA; Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA
| | - Carsten Schultz
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97210, USA.
| |
Collapse
|
18
|
Nguyen TQ, Kim JE, Brawley HN, Lindahl PA. Chromatographic detection of low-molecular-mass metal complexes in the cytosol of Saccharomyces cerevisiae. Metallomics 2020; 12:1094-1105. [PMID: 32301942 PMCID: PMC7497409 DOI: 10.1039/c9mt00312f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Fluorescence-based chelators are commonly used to probe labile low-molecular-mass (LMM) metal pools in the cytosol of eukaryotic cells, but such chelators destroy the complexes of interest during detection. The objective of this study was to use chromatography to directly detect such complexes. Towards this end, 47 batches of cytosol were isolated from fermenting S. cerevisiae yeast cells and passed through a 10 kDa cut-off membrane. The metal contents of the cytosol and resulting flow-through solution (FTS) were determined. FTSs were applied to a size-exclusion LC column located in an anaerobic refrigerated glove box. The LC system was coupled to an online inductively-coupled-plasma mass spectrometer (ICP-MS) for detection of individual metals. Iron-detected chromatograms of cytosolic FTSs from WT cells exhibited 2-4 major species with apparent masses between 500-1300 Da. Increasing the iron concentration in the growth medium 40-fold increased the overall intensity of these peaks. Approximately 3 LMM cytosolic copper complexes with apparent masses between 300-1300 Da were also detected; their LC intensities were weak, but these increased with increasing concentrations of copper in the growth medium. Observed higher-mass copper-detected peaks were tentatively assigned to copper-bound metallothioneins Cup1 and Crs5. FTSs from strains in which Cup1 or the Cox17 copper chaperone were deleted altered the distribution of LMM copper complexes. LMM zinc- and manganese-detected species were also present in cytosol, albeit at low concentrations. Supplementing the growth medium with zinc increased the intensity of the zinc peak assigned to Crs5 but the intensities of LMM zinc complexes were unaffected. Phosphorus-detected chromatograms were dominated by peaks at apparent masses 400-800 Da, with minor peaks at 1000-1500 Da in some batches. Sulfur chromatograms contained a low-intensity peak that comigrated with a glutathione standard; quantification suggested a GSH concentration in the cytosol of ca. 13 mM. A second LMM sulfur peak that migrated at an apparent mass of 100 Da was also evident.
Collapse
Affiliation(s)
- Trang Q Nguyen
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA.
| | | | | | | |
Collapse
|
19
|
Copley SD. The physical basis and practical consequences of biological promiscuity. Phys Biol 2020; 17:10.1088/1478-3975/ab8697. [PMID: 32244231 PMCID: PMC9291633 DOI: 10.1088/1478-3975/ab8697] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Proteins interact with metabolites, nucleic acids, and other proteins to orchestrate the myriad catalytic, structural and regulatory functions that support life from the simplest microbes to the most complex multicellular organisms. These molecular interactions are often exquisitely specific, but never perfectly so. Adventitious "promiscuous" interactions are ubiquitous due to the thousands of macromolecules and small molecules crowded together in cells. Such interactions may perturb protein function at the molecular level, but as long as they do not compromise organismal fitness, they will not be removed by natural selection. Although promiscuous interactions are physiologically irrelevant, they are important because they can provide a vast reservoir of potential functions that can provide the starting point for evolution of new functions, both in nature and in the laboratory.
Collapse
Affiliation(s)
- Shelley D Copley
- Department of Molecular, Cellular and Developmental Biology and Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, UNITED STATES
| |
Collapse
|
20
|
Maares M, Haase H. A Guide to Human Zinc Absorption: General Overview and Recent Advances of In Vitro Intestinal Models. Nutrients 2020; 12:E762. [PMID: 32183116 PMCID: PMC7146416 DOI: 10.3390/nu12030762] [Citation(s) in RCA: 146] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/23/2020] [Accepted: 03/09/2020] [Indexed: 12/17/2022] Open
Abstract
Zinc absorption in the small intestine is one of the main mechanisms regulating the systemic homeostasis of this essential trace element. This review summarizes the key aspects of human zinc homeostasis and distribution. In particular, current knowledge on human intestinal zinc absorption and the influence of diet-derived factors on bioaccessibility and bioavailability as well as intrinsic luminal and basolateral factors with an impact on zinc uptake are discussed. Their investigation is increasingly performed using in vitro cellular intestinal models, which are continually being refined and keep gaining importance for studying zinc uptake and transport via the human intestinal epithelium. The vast majority of these models is based on the human intestinal cell line Caco-2 in combination with other relevant components of the intestinal epithelium, such as mucin-secreting goblet cells and in vitro digestion models, and applying improved compositions of apical and basolateral media to mimic the in vivo situation as closely as possible. Particular emphasis is placed on summarizing previous applications as well as key results of these models, comparing their results to data obtained in humans, and discussing their advantages and limitations.
Collapse
Affiliation(s)
- Maria Maares
- Technische Universität Berlin, Chair of Food Chemistry and Toxicology, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Hajo Haase
- Technische Universität Berlin, Chair of Food Chemistry and Toxicology, Straße des 17. Juni 135, 10623 Berlin, Germany
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, D-13353 Potsdam-Berlin-Jena, Germany
| |
Collapse
|
21
|
Sub-nanomolar sensitive GZnP3 reveals TRPML1-mediated neuronal Zn 2+ signals. Nat Commun 2019; 10:4806. [PMID: 31641116 PMCID: PMC6805855 DOI: 10.1038/s41467-019-12761-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 09/27/2019] [Indexed: 02/07/2023] Open
Abstract
Although numerous fluorescent Zn2+ sensors have been reported, it is unclear whether and how Zn2+ can be released from the intracellular compartments into the cytosol due to a lack of probes that can detect physiological dynamics of cytosolic Zn2+. Here, we create a genetically encoded sensor, GZnP3, which demonstrates unprecedented sensitivity for Zn2+ at sub-nanomolar concentrations. Using GZnP3 as well as GZnP3-derived vesicular targeted probes, we provide the first direct evidence that Zn2+ can be released from endolysosomal vesicles to the cytosol in primary hippocampal neurons through the TRPML1 channel. Such TRPML1-mediated Zn2+ signals are distinct from Ca2+ in that they are selectively present in neurons, sustain longer, and are significantly higher in neurites as compared to the soma. Together, our work not only creates highly sensitive probes for investigating sub-nanomolar Zn2+ dynamics, but also reveals new pools of Zn2+ signals that can play critical roles in neuronal function. Numerous fluorescent Zn2+ sensors are available but most are unsuitable to detect physiological dynamics of cytosolic Zn2+. In this study, the authors present a genetically encoded sensor with sub-nanomolar sensitivity and show that Zn2 + is released from endolysosomal vesicles via TRPML1 in neurons.
Collapse
|
22
|
Intracellular Zn 2+ transients modulate global gene expression in dissociated rat hippocampal neurons. Sci Rep 2019; 9:9411. [PMID: 31253848 PMCID: PMC6598991 DOI: 10.1038/s41598-019-45844-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/07/2019] [Indexed: 12/22/2022] Open
Abstract
Zinc (Zn2+) is an integral component of many proteins and has been shown to act in a regulatory capacity in different mammalian systems, including as a neurotransmitter in neurons throughout the brain. While Zn2+ plays an important role in modulating neuronal potentiation and synaptic plasticity, little is known about the signaling mechanisms of this regulation. In dissociated rat hippocampal neuron cultures, we used fluorescent Zn2+ sensors to rigorously define resting Zn2+ levels and stimulation-dependent intracellular Zn2+ dynamics, and we performed RNA-Seq to characterize Zn2+-dependent transcriptional effects upon stimulation. We found that relatively small changes in cytosolic Zn2+ during stimulation altered expression levels of 931 genes, and these Zn2+ dynamics induced transcription of many genes implicated in neurite expansion and synaptic growth. Additionally, while we were unable to verify the presence of synaptic Zn2+ in these cultures, we did detect the synaptic vesicle Zn2+ transporter ZnT3 and found it to be substantially upregulated by cytosolic Zn2+ increases. These results provide the first global sequencing-based examination of Zn2+-dependent changes in transcription and identify genes that may mediate Zn2+-dependent processes and functions.
Collapse
|
23
|
Chabosseau P, Woodier J, Cheung R, Rutter GA. Sensors for measuring subcellular zinc pools. Metallomics 2019; 10:229-239. [PMID: 29431830 DOI: 10.1039/c7mt00336f] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Zinc homeostasis is essential for normal cellular function, and defects in this process are associated with a number of diseases including type 2 diabetes (T2D), neurological disorders and cardiovascular disease. Thus, variants in the SLC30A8 gene, encoding the vesicular/granular zinc transporter ZnT8, are associated with altered insulin release and increased T2D risk while the zinc importer ZIP12 is implicated in pulmonary hypertension. In light of these, and findings in other diseases, recent efforts have focused on the development of refined sensors for intracellular free zinc ions that can be targeted to subcellular regions including the cytosol, endoplasmic reticulum (ER), secretory granules, Golgi apparatus, nucleus and the mitochondria. Here, we discuss recent advances in Zn2+ probe engineering and their applications to the measurement of labile subcellular zinc pools in different cell types.
Collapse
Affiliation(s)
- Pauline Chabosseau
- Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
| | | | | | | |
Collapse
|
24
|
Superiority of SpiroZin2 Versus FluoZin-3 for monitoring vesicular Zn 2+ allows tracking of lysosomal Zn 2+ pools. Sci Rep 2018; 8:15034. [PMID: 30302024 PMCID: PMC6177427 DOI: 10.1038/s41598-018-33102-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 09/17/2018] [Indexed: 12/28/2022] Open
Abstract
Small-molecule fluorescent probes are powerful and ubiquitous tools for measuring the concentration and distribution of analytes in living cells. However, accurate characterization of these analytes requires rigorous evaluation of cell-to-cell heterogeneity in fluorescence intensities and intracellular distribution of probes. In this study, we perform a parallel and systematic comparison of two small-molecule fluorescent vesicular Zn2+ probes, FluoZin-3 AM and SpiroZin2, to evaluate each probe for measurement of vesicular Zn2+ pools. Our results reveal that SpiroZin2 is a specific lysosomal vesicular Zn2+ probe and affords uniform measurement of resting Zn2+ levels at the single cell level with proper calibration. In contrast, FluoZin-3 AM produces highly variable fluorescence intensities and non-specifically localizes in the cytosol and multiple vesicular compartments. We further applied SpiroZin2 to lactating mouse mammary epithelial cells and detected a transient increase of lysosomal free Zn2+ at 24-hour after lactation hormone treatment, which implies that lysosomes play a role in the regulation of Zn2+ homeostasis during lactation. This study demonstrates the need for critical characterization of small-molecule fluorescent probes to define the concentration and localization of analytes in different cell populations, and reveals SpiroZin2 to be capable of reporting diverse perturbations to lysosomal Zn2+.
Collapse
|
25
|
Holliday MJ, Ferrao R, de Leon Boenig G, Estevez A, Helgason E, Rohou A, Dueber EC, Fairbrother WJ. Picomolar zinc binding modulates formation of Bcl10-nucleating assemblies of the caspase recruitment domain (CARD) of CARD9. J Biol Chem 2018; 293:16803-16817. [PMID: 30206119 DOI: 10.1074/jbc.ra118.004821] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/04/2018] [Indexed: 12/28/2022] Open
Abstract
The caspase recruitment domain-containing protein 9 (CARD9)-B-cell lymphoma/leukemia 10 (Bcl10) signaling axis is activated in myeloid cells during the innate immune response to a variety of diverse pathogens. This signaling pathway requires a critical caspase recruitment domain (CARD)-CARD interaction between CARD9 and Bcl10 that promotes downstream activation of factors, including NF-κB and the mitogen-activated protein kinase (MAPK) p38. Despite these insights, CARD9 remains structurally uncharacterized, and little mechanistic understanding of its regulation exists. We unexpectedly found here that the CARD in CARD9 binds to Zn2+ with picomolar affinity-a concentration comparable with the levels of readily accessible Zn2+ in the cytosol. NMR solution structures of the CARD9-CARD in the apo and Zn2+-bound states revealed that Zn2+ has little effect on the ground-state structure of the CARD; yet the stability of the domain increased considerably upon Zn2+ binding, with a concomitant reduction in conformational flexibility. Moreover, Zn2+ binding inhibited polymerization of the CARD9-CARD into helical assemblies. Here, we also present a 20-Å resolution negative-stain EM (NS-EM) structure of these filamentous assemblies and show that they adopt a similar helical symmetry as reported previously for filaments of the Bcl10 CARD. Using both bulk assays and direct NS-EM visualization, we further show that the CARD9-CARD assemblies can directly template and thereby nucleate Bcl10 polymerization, a capacity considered critical to propagation of the CARD9-Bcl10 signaling cascade. Our findings indicate that CARD9 is a potential target of Zn2+-mediated signaling that affects Bcl10 polymerization in innate immune responses.
Collapse
Affiliation(s)
| | - Ryan Ferrao
- Structural Biology Department, Genentech, South San Francisco, California 94080
| | | | - Alberto Estevez
- Structural Biology Department, Genentech, South San Francisco, California 94080
| | | | - Alexis Rohou
- Structural Biology Department, Genentech, South San Francisco, California 94080
| | - Erin C Dueber
- From the Early Discovery Biochemistry Department and
| | | |
Collapse
|
26
|
Maares M, Keil C, Thomsen S, Günzel D, Wiesner B, Haase H. Characterization of Caco-2 cells stably expressing the protein-based zinc probe eCalwy-5 as a model system for investigating intestinal zinc transport. J Trace Elem Med Biol 2018; 49:296-304. [PMID: 29395783 DOI: 10.1016/j.jtemb.2018.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/22/2017] [Accepted: 01/17/2018] [Indexed: 12/30/2022]
Abstract
Intestinal zinc resorption, in particular its regulation and mechanisms, are not yet fully understood. Suitable intestinal cell models are needed to investigate zinc uptake kinetics and the role of labile zinc in enterocytes in vitro. Therefore, a Caco-2 cell clone was produced, stably expressing the genetically encoded zinc biosensor eCalwy-5. The aim of the present study was to reassure the presence of characteristic enterocyte-specific properties in the Caco-2-eCalwy clone. Comparison of Caco-2-WT and Caco-2-eCalwy cells revealed only slight differences regarding subcellular localization of the tight junction protein occludin and alkaline phosphatase activity, which did not affect basic integrity of the intestinal barrier or the characteristic brush border membrane morphology. Furthermore, introduction of the additional zinc-binding protein in Caco-2 cells did not alter mRNA expression of the major intestinal zinc transporters (zip4, zip5, znt-1 and znt-5), but increased metallothionein 1a-expression and cellular resistance to higher zinc concentrations. Moreover, this study examines the effect of sensor expression level on its saturation with zinc. Fluorescence cell imaging indicated considerable intercellular heterogeneity in biosensor-expression. However, FRET-measurements confirmed that these differences in expression levels have no effect on fractional zinc-saturation of the probe.
Collapse
Affiliation(s)
- Maria Maares
- Department of Food Chemistry and Toxicology, Berlin Institute of Technology, Berlin, Germany
| | - Claudia Keil
- Department of Food Chemistry and Toxicology, Berlin Institute of Technology, Berlin, Germany
| | - Susanne Thomsen
- Department of Food Chemistry and Toxicology, Berlin Institute of Technology, Berlin, Germany
| | - Dorothee Günzel
- Institute of Clinical Physiology, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | | | - Hajo Haase
- Department of Food Chemistry and Toxicology, Berlin Institute of Technology, Berlin, Germany; TraceAge-DFG Research Unit on Interactions of essential trace elements in healthy and diseased elderly, Potsdam-Berlin-Jena, Germany.
| |
Collapse
|
27
|
Marszałek I, Goch W, Bal W. Ternary Zn(II) Complexes of FluoZin-3 and the Low Molecular Weight Component of the Exchangeable Cellular Zinc Pool. Inorg Chem 2018; 57:9826-9838. [PMID: 30088924 DOI: 10.1021/acs.inorgchem.8b00489] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Knowledge of the nature of exchangeable (labile) intracellular Zn(II) is increasingly important for biomedical research. The detection and quantitative determination of Zn(II) ions is usually performed by using Zn(II)-specific fluorescent sensors, among which 2-[2-[2-[2-[bis(carboxylatomethyl)amino]-5-methoxyphenoxy]ethoxy]-4-(2,7-difluoro-3-oxido-6-oxo-4a,9a-dihydroxanthen-9-yl)anilino]acetate (FluoZin-3) has been used most widely. Selectivity of this sensor for Zn(II) over other divalent cations was demonstrated, but possible interference in its performance by other compounds has not been investigated. Many potential low molecular weight ligands for Zn(II) ions (LMWLs) are abundant in the cell. In this study we demonstrate that FluoZin-3 is susceptible to competition for Zn(II) from LMWLs and also forms strong ternary complexes with some of them. We determined the set of conditional stability constants C Ktern for ternary Zn(FluoZin-3)(LMWL) complexes using fluorescence titrations and applied it to model the response of exchangeable zinc to FluoZin-3. We found that competition and formation of ternary complexes with LMWLs together strongly affect (net reduce) the Zn(FluoZin-3) fluorescence. This effect may cause a significant underestimation of exchangeable Zn(II). We also demonstrated a strong pH dependence of this effect. Reduced glutathione (GSH) emerged as the most important Zn(II) partner among the LMWLs, characterized with Ktern = 2.8 ± 0.2 × 106 M-1. Our experiments and calculations suggest that Zn(LMWL) complexes contribute to the exchangeable cellular zinc pool.
Collapse
Affiliation(s)
- Ilona Marszałek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences , Pawińskiego 5a , 02-106 Warsaw , Poland
| | - Wojciech Goch
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences , Pawińskiego 5a , 02-106 Warsaw , Poland.,Faculty of Pharmacy , Medical University of Warsaw , Banacha 1 , 02-091 Warsaw , Poland
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences , Pawińskiego 5a , 02-106 Warsaw , Poland
| |
Collapse
|
28
|
Mehta R, Qureshi MH, Purchal MK, Greer SM, Gong S, Ngo C, Que EL. A new probe for detecting zinc-bound carbonic anhydrase in cell lysates and cells. Chem Commun (Camb) 2018; 54:5442-5445. [PMID: 29745391 DOI: 10.1039/c8cc02034e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We report the synthesis and application of a small molecule probe for carbonic anhydrase (CA) to track holo-CA in cell lysates and live-cell models of zinc dyshomeostasis. The probe displays a 12-fold increase in fluorescence upon binding to bovine CA and also responds to human CA isoforms.
Collapse
Affiliation(s)
- Radhika Mehta
- Department of Chemistry, University of Texas at Austin, 105 E 24th St Stop A5300, Austin, TX 78712, USA.
| | | | | | | | | | | | | |
Collapse
|
29
|
Wetherell D, Baldwin GS, Shulkes A, Bolton D, Ischia J, Patel O. Zinc ion dyshomeostasis increases resistance of prostate cancer cells to oxidative stress via upregulation of HIF1α. Oncotarget 2018; 9:8463-8477. [PMID: 29492208 PMCID: PMC5823553 DOI: 10.18632/oncotarget.23893] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 11/14/2017] [Indexed: 12/16/2022] Open
Abstract
Zinc ions (Zn2+) are known to influence cell survival and proliferation. However the homeostatic regulation of Zn2+ and their role in prostate cancer (PC) progression is poorly understood. Therefore the subcellular distribution and uptake of Zn2+ in PC cells were investigated. Inductively coupled plasma mass spectroscopy and fluorescent microscopy with the Zn2+-specific fluorescent probe FluoZin-3 were used to quantify total and free Zn2+, respectively, in the normal prostate epithelial cell line (PNT1A) and three human PC cell lines (PC3, DU145 and LNCaP). The effects of Zn2+ treatment on proliferation and survival were measured in vitro using MTT assays and in vivo using mouse xenografts. The ability of Zn2+ to protect against oxidative stress via a HIF1α-dependent mechanism was investigated using a HIF1α knock-down PC3 model. Our results demonstrate that the total Zn2+ concentration in normal PNT1A and PC cells is similar, but PC3 cells contain significantly higher free Zn2+ than PNT1A cells (p < 0.01). PNT1A cells can survive better in the presence of high concentrations of Zn2+ than PC3 cells. Exposure to 10 µM Zn2+ over 72 hours significantly reduces PC3 cell proliferation in vitro but not in vivo. Zn2+ increases PC3 cell survival up to 2.3-fold under oxidative stress, and this protective effect is not seen in PNT1A cells or in a HIF1α-KD PC3 cell model. A state of Zn2+ dyshomeostasis exists in PC. HIF1α is an integral component of a Zn2+-dependent protective mechanism present in PC3 cells. This pathway may be clinically significant through its contribution to castrate-resistant PC survival.
Collapse
Affiliation(s)
- David Wetherell
- Department of Surgery, University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia.,Department of Urology, Austin Health, Heidelberg, Victoria, 3084, Australia
| | - Graham S Baldwin
- Department of Surgery, University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia
| | - Arthur Shulkes
- Department of Surgery, University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia
| | - Damien Bolton
- Department of Surgery, University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia.,Department of Urology, Austin Health, Heidelberg, Victoria, 3084, Australia
| | - Joseph Ischia
- Department of Surgery, University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia.,Department of Urology, Austin Health, Heidelberg, Victoria, 3084, Australia
| | - Oneel Patel
- Department of Surgery, University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia
| |
Collapse
|
30
|
New EJ, Wimmer VC, Hare DJ. Promises and Pitfalls of Metal Imaging in Biology. Cell Chem Biol 2017; 25:7-18. [PMID: 29153850 DOI: 10.1016/j.chembiol.2017.10.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/02/2017] [Accepted: 10/18/2017] [Indexed: 10/18/2022]
Abstract
A picture may speak a thousand words, but if those words fail to form a coherent sentence there is little to be learned. As cutting-edge imaging technology now provides us the tools to decipher the multitude of roles played by metals and metalloids in molecular, cellular, and developmental biology, as well as health and disease, it is time to reflect on the advances made in imaging, the limitations discovered, and the future of a burgeoning field. In this Perspective, the current state of the art is discussed from a self-imposed contrarian position, as we not only highlight the major advances made over the years but use them as teachable moments to zoom in on challenges that remain to be overcome. We also describe the steps being taken toward being able to paint a completely undisturbed picture of cellular metal metabolism, which is, metaphorically speaking, the Holy Grail of the discipline.
Collapse
Affiliation(s)
- Elizabeth J New
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Verena C Wimmer
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia
| | - Dominic J Hare
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia; Elemental Bio-imaging Facility, University of Technology Sydney, Broadway, NSW 2007, Australia; Department of Pathology, The University of Melbourne, Parkville, VIC 3052, Australia.
| |
Collapse
|
31
|
Carter KP, Carpenter MC, Fiedler B, Jimenez R, Palmer AE. Critical Comparison of FRET-Sensor Functionality in the Cytosol and Endoplasmic Reticulum and Implications for Quantification of Ions. Anal Chem 2017; 89:9601-9608. [PMID: 28758723 DOI: 10.1021/acs.analchem.7b02933] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Genetically encoded sensors based on fluorescence resonance energy transfer (FRET) are powerful tools for quantifying and visualizing analytes in living cells, and when targeted to organelles have the potential to define distribution of analytes in different parts of the cell. However, quantitative estimates of analyte distribution require rigorous and systematic analysis of sensor functionality in different locations. In this work, we establish methods to critically evaluate sensor performance in different organelles and carry out a side-by-side comparison of three different genetically encoded sensor platforms for quantifying cellular zinc ions (Zn2+). Calibration conditions are optimized for high dynamic range and stable FRET signals. Using a combination of single-cell microscopy and a novel microfluidic platform capable of screening thousands of cells in a few hours, we observe differential performance of these sensors in the cytosol compared to the ER of HeLa cells, and identify the formation of oxidative oligomers of the sensors in the ER. Finally, we use new methodology to re-evaluate the binding parameters of these sensors both in the test tube and in living cells. Ultimately, we demonstrate that sensor responses can be affected by different cellular environments, and provide a framework for evaluating future generations of organelle-targeted sensors.
Collapse
Affiliation(s)
- Kyle P Carter
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,BioFrontiers Institute, University of Colorado , Boulder, Colorado 80303, United States
| | - Margaret C Carpenter
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,BioFrontiers Institute, University of Colorado , Boulder, Colorado 80303, United States
| | - Brett Fiedler
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,JILA, University of Colorado and National Institute of Standards and Technology , Boulder, Colorado 80309, United States
| | - Ralph Jimenez
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,JILA, University of Colorado and National Institute of Standards and Technology , Boulder, Colorado 80309, United States
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,BioFrontiers Institute, University of Colorado , Boulder, Colorado 80303, United States
| |
Collapse
|
32
|
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: 259] [Impact Index Per Article: 37.0] [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.
Collapse
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.
| |
Collapse
|
33
|
Mobile zinc increases rapidly in the retina after optic nerve injury and regulates ganglion cell survival and optic nerve regeneration. Proc Natl Acad Sci U S A 2017; 114:E209-E218. [PMID: 28049831 DOI: 10.1073/pnas.1616811114] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Retinal ganglion cells (RGCs), the projection neurons of the eye, cannot regenerate their axons once the optic nerve has been injured and soon begin to die. Whereas RGC death and regenerative failure are widely viewed as being cell-autonomous or influenced by various types of glia, we report here that the dysregulation of mobile zinc (Zn2+) in retinal interneurons is a primary factor. Within an hour after the optic nerve is injured, Zn2+ increases several-fold in retinal amacrine cell processes and continues to rise over the first day, then transfers slowly to RGCs via vesicular release. Zn2+ accumulation in amacrine cell processes involves the Zn2+ transporter protein ZnT-3, and deletion of slc30a3, the gene encoding ZnT-3, promotes RGC survival and axon regeneration. Intravitreal injection of Zn2+ chelators enables many RGCs to survive for months after nerve injury and regenerate axons, and enhances the prosurvival and regenerative effects of deleting the gene for phosphatase and tensin homolog (pten). Importantly, the therapeutic window for Zn2+ chelation extends for several days after nerve injury. These results show that retinal Zn2+ dysregulation is a major factor limiting the survival and regenerative capacity of injured RGCs, and point to Zn2+ chelation as a strategy to promote long-term RGC protection and enhance axon regeneration.
Collapse
|
34
|
Hessels AM, Taylor KM, Merkx M. Monitoring cytosolic and ER Zn(2+) in stimulated breast cancer cells using genetically encoded FRET sensors. Metallomics 2016; 8:211-7. [PMID: 26739447 PMCID: PMC4756312 DOI: 10.1039/c5mt00257e] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Zn(2+)-specific ion channel ZIP7 has been implicated to play an important role in releasing Zn(2+) from the ER. External stimulation of breast cancer cells has been proposed to induce phosphorylation of ZIP7 by CK2α, resulting in ZIP7-mediated Zn(2+) release from the ER into the cytosol. Here, we examined whether changes in cytosolic and ER Zn(2+) concentrations can be detected upon such external stimuli. Two previously developed FRET sensors for Zn(2+), eZinCh-2 (Kd = 1 nM at pH 7.1) and eCALWY-4 (Kd = 0.63 nM at pH 7.1), were expressed in both the cytosol and the ER of wild-type MCF-7 and TamR cells. Treatment of MCF-7 and TamR cells with external Zn(2+) and pyrithione, one of the previously used triggers, resulted in an immediate increase in free Zn(2+) in both cytosol and ER, suggesting that Zn(2+) was directly transferred across the cellular membranes by pyrithione. Cells treated with a second trigger, EGF/ionomycin, showed no changes in intracellular Zn(2+) levels, neither in multicolor imaging experiments that allowed simultaneous imaging of cytosolic and ER Zn(2+), nor in experiments in which cytosolic and ER Zn(2+) were monitored separately. In contrast to previous work using small-molecule fluorescent dyes, these results indicate that EGF-ionomycin treatment does not result in significant changes in cytosolic Zn(2+) levels as a result from Zn(2+) release from the ER. These results underline the importance of using genetically encoded fluorescent sensors to complement and verify intracellular imaging experiments with synthetic fluorescent Zn(2+) dyes.
Collapse
Affiliation(s)
- Anne M Hessels
- Laboratory of Chemical Biology and Institute of Complex Molecular Systems (ICMS), Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - Kathryn M Taylor
- Breast Cancer Molecular Pharmacology Group, School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, UK
| | - Maarten Merkx
- Laboratory of Chemical Biology and Institute of Complex Molecular Systems (ICMS), Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| |
Collapse
|
35
|
Petering DH. Reactions of the Zn Proteome with Cd2+ and Other Xenobiotics: Trafficking and Toxicity. Chem Res Toxicol 2016; 30:189-202. [DOI: 10.1021/acs.chemrestox.6b00328] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- David H. Petering
- Department of Chemistry and
Biochemistry, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53201, United States
| |
Collapse
|
36
|
Abstract
![]()
Genetically encoded
FRET-based sensor proteins have significantly
contributed to our current understanding of the intracellular functions
of Zn2+. However, the external excitation required for
these fluorescent sensors can give rise to photobleaching and phototoxicity
during long-term imaging, limits applications that suffer from autofluorescence
and light scattering, and is not compatible with light-sensitive cells.
For these applications, sensor proteins based on Bioluminescence Resonance
Energy Transfer (BRET) would provide an attractive alternative. In
this work, we used the bright and stable luciferase NanoLuc to create
the first genetically encoded BRET sensors for measuring intracellular
Zn2+. Using a new sensor approach, the NanoLuc domain was
fused to the Cerulean donor domain of two previously developed FRET
sensors, eCALWY and eZinCh-2. In addition to preserving the excellent
Zn2+ affinity and specificity of their predecessors, these
newly developed sensors enable both BRET- and FRET-based detection.
While the dynamic range of the BRET signal for the eCALWY-based BLCALWY-1
sensor was limited by the presence of two competing BRET pathways,
BRET/FRET sensors based on the eZinCh-2 scaffold (BLZinCh-1 and -2)
yielded robust 25–30% changes in BRET ratio. In addition, introduction
of a chromophore-silencing mutation resulted in a BRET-only sensor
(BLZinCh-3) with increased BRET response (50%) and an unexpected 10-fold
increase in Zn2+ affinity. The combination of robust ratiometric
response, physiologically relevant Zn2+ affinities, and
stable and bright luminescence signal offered by the BLZinCh sensors
allowed monitoring of intracellular Zn2+ in plate-based
assays as well as intracellular BRET-based imaging in single living
cells in real time.
Collapse
Affiliation(s)
- Stijn J. A. Aper
- Laboratory
of Chemical Biology and Institute for Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Pieterjan Dierickx
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
- Division
of Heart and Lungs, Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Maarten Merkx
- Laboratory
of Chemical Biology and Institute for Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| |
Collapse
|
37
|
Qin Y, Sammond DW, Braselmann E, Carpenter MC, Palmer AE. Development of an Optical Zn 2+ Probe Based on a Single Fluorescent Protein. ACS Chem Biol 2016; 11:2744-2751. [PMID: 27467056 DOI: 10.1021/acschembio.6b00442] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Various fluorescent probes have been developed to reveal the biological functions of intracellular labile Zn2+. Here, we present Green Zinc Probe (GZnP), a novel genetically encoded Zn2+ sensor design based on a single fluorescent protein (single-FP). The GZnP sensor is generated by attaching two zinc fingers (ZF) of the transcription factor Zap1 (ZF1 and ZF2) to the two ends of a circularly permuted green fluorescent protein (cpGFP). Formation of ZF folds induces interaction between the two ZFs, which induces a change in the cpGFP conformation, leading to an increase in fluorescence. A small sensor library is created to include mutations in the ZFs, cpGFP and linkers between ZF and cpGFP to improve signal stability, sensor brightness and dynamic range based on rational protein engineering, and computational design by Rosetta. Using a cell-based library screen, we identify sensor GZnP1, which demonstrates a stable maximum signal, decent brightness (QY = 0.42 at apo state), as well as specific and sensitive response to Zn2+ in HeLa cells (Fmax/Fmin = 2.6, Kd = 58 pM, pH 7.4). The subcellular localizing sensors mito-GZnP1 (in mitochondria matrix) and Lck-GZnP1 (on plasma membrane) display sensitivity to Zn2+ (Fmax/Fmin = 2.2). This sensor design provides freedom to be used in combination with other optical indicators and optogenetic tools for simultaneous imaging and advancing our understanding of cellular Zn2+ function.
Collapse
Affiliation(s)
- Yan Qin
- Department
of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Deanne W. Sammond
- Biosciences
Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Esther Braselmann
- Department
of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Margaret C. Carpenter
- Department
of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Amy E. Palmer
- Department
of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| |
Collapse
|
38
|
Carpenter MC, Lo MN, Palmer AE. Techniques for measuring cellular zinc. Arch Biochem Biophys 2016; 611:20-29. [PMID: 27580940 DOI: 10.1016/j.abb.2016.08.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 08/19/2016] [Accepted: 08/23/2016] [Indexed: 02/08/2023]
Abstract
The development and improvement of fluorescent Zn2+ sensors and Zn2+ imaging techniques have increased our insight into this biologically important ion. Application of these tools has identified an intracellular labile Zn2+ pool and cultivated further interest in defining the distribution and dynamics of labile Zn2+. The study of Zn2+ in live cells in real time using sensors is a powerful way to answer complex biological questions. In this review, we highlight newly engineered Zn2+ sensors, methods to test whether the sensors are accessing labile Zn2+, and recent studies that point to the challenges of using such sensors. Elemental mapping techniques can complement and strengthen data collected with sensors. Both mass spectrometry-based and X-ray fluorescence-based techniques yield highly specific, sensitive, and spatially resolved snapshots of metal distribution in cells. The study of Zn2+ has already led to new insight into all phases of life from fertilization of the egg to life-threatening cancers. In order to continue building new knowledge about Zn2+ biology it remains important to critically assess the available toolset for this endeavor.
Collapse
Affiliation(s)
- Margaret C Carpenter
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, United States.
| | - Maria N Lo
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, United States.
| | - Amy E Palmer
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, United States.
| |
Collapse
|
39
|
Unraveling the mystery of the ring: Tracking heme dynamics in living cells. Proc Natl Acad Sci U S A 2016; 113:7296-7. [PMID: 27342864 DOI: 10.1073/pnas.1607505113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
40
|
Liang X, Dempski RE, Burdette SC. Zn(2+) at a cellular crossroads. Curr Opin Chem Biol 2016; 31:120-5. [PMID: 27010344 PMCID: PMC4870122 DOI: 10.1016/j.cbpa.2016.02.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/18/2016] [Indexed: 11/27/2022]
Abstract
Zinc is an essential micronutrient for cellular homeostasis. Initially proposed to only contribute to cellular viability through structural roles and non-redox catalysis, advances in quantifying changes in nM and pM quantities of Zn(2+) have elucidated increasing functions as an important signaling molecule. This includes Zn(2+)-mediated regulation of transcription factors and subsequent protein expression, storage and release of intracellular compartments of zinc quanta into the extracellular space which modulates plasma membrane protein function, as well as intracellular signaling pathways which contribute to the immune response. This review highlights some recent advances in our understanding of zinc signaling.
Collapse
Affiliation(s)
- Xiaomeng Liang
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, Worcester, MA 01609-2280, United States
| | - Robert E Dempski
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, Worcester, MA 01609-2280, United States
| | - Shawn C Burdette
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, Worcester, MA 01609-2280, United States.
| |
Collapse
|
41
|
Zinc sensing and regulation in yeast model systems. Arch Biochem Biophys 2016; 611:30-36. [PMID: 26940262 DOI: 10.1016/j.abb.2016.02.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 02/25/2016] [Accepted: 02/27/2016] [Indexed: 11/23/2022]
Abstract
The Zap1 transcription factor of Saccharomyces cerevisiae and the Loz1 transcription factor of Schizosaccharomyces pombe both play a central role in zinc homeostasis by controlling the expression of genes necessary for zinc metabolism. Zap1 activates gene expression when cells are limited for zinc, while Loz1 is required for gene repression when zinc is in excess. In this review we highlight what is known about the underlying mechanisms by which these factors are regulated by zinc, and how transcriptional activation and repression in eukaryotic cells can be finely tuned according to intracellular zinc availability.
Collapse
|
42
|
Abstract
Metal ions play an important role in various biological processes, their abnormal homeostasis in cells is related to many diseases, such as neurodegenerative disease, cancer and diabetes. Fluorescent imaging offers a unique route to detect metal ions in cells via a contactless and damage-free way with high spatial and temporal fidelity. Consequently, it represents a promising method to advance the understanding of physiological and pathological functions of metal ions in cell biology. In this highlight article, we will discuss recent advances in fluorescent imaging of metal ions by small-molecule sensors for understanding the role of metals in related diseases. We will also discuss challenges and opportunities for the design of small-molecule sensors for fluorescent detection of cellular metal ions as a potential method for disease diagnosis.
Collapse
Affiliation(s)
- Xuhong Qian
- Shanghai Key Laboratory of Chemical Biology, State Key Laboratory of Bioreactor Engineering, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
| | | |
Collapse
|
43
|
Zastrow ML, Radford RJ, Chyan W, Anderson CT, Zhang DY, Loas A, Tzounopoulos T, Lippard SJ. Reaction-Based Probes for Imaging Mobile Zinc in Live Cells and Tissues. ACS Sens 2016; 1:32-39. [PMID: 26878065 PMCID: PMC4732192 DOI: 10.1021/acssensors.5b00022] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 09/23/2015] [Indexed: 12/22/2022]
Abstract
Chelatable, or mobile, forms of zinc play critical signaling roles in numerous biological processes. Elucidating the action of mobile Zn(II) in complex biological environments requires sensitive tools for visualizing, tracking, and manipulating Zn(II) ions. A large toolbox of synthetic photoinduced electron transfer (PET)-based fluorescent Zn(II) sensors are available, but the applicability of many of these probes is limited by poor zinc sensitivity and low dynamic ranges owing to proton interference. We present here a general approach for acetylating PET-based probes containing a variety of fluorophores and zinc-binding units. The new sensors provide substantially improved zinc sensitivity and allow for incubation of live cells and tissue slices with nM probe concentrations, a significant improvement compared to the μM concentrations that are typically required for a measurable fluorescence signal. Acetylation effectively reduces or completely quenches background fluorescence in the metal-free sensor. Binding of Zn(II) selectively and quickly mediates hydrolytic cleavage of the acetyl groups, providing a large fluorescence response. An acetylated blue coumarin-based sensor was used to carry out detailed analyses of metal binding and metal-promoted acetyl hydrolysis. Acetylated benzoresorufin-based red-emitting probes with different zinc-binding sites are effective for sensing Zn(II) ions in live cells when applied at low concentrations (∼50-100 nM). We used green diacetylated Zinpyr1 (DA-ZP1) to image endogenous mobile Zn(II) in the molecular layer of mouse dorsal cochlear nucleus (DCN), confirming that acetylation is a suitable approach for preparing sensors that are highly specific and sensitive to mobile zinc in biological systems.
Collapse
Affiliation(s)
- Melissa L. Zastrow
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert J. Radford
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wen Chyan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Charles T. Anderson
- Departments of Otolaryngology and Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Daniel Y. Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Andrei Loas
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Thanos Tzounopoulos
- Departments of Otolaryngology and Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Stephen J. Lippard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
44
|
Luminescent Silica Nanoparticles Featuring Collective Processes for Optical Imaging. Top Curr Chem (Cham) 2016; 370:1-28. [DOI: 10.1007/978-3-319-22942-3_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
45
|
Rivera-Fuentes P, Lippard SJ. Metal-based optical probes for live cell imaging of nitroxyl (HNO). Acc Chem Res 2015; 48:2927-34. [PMID: 26550842 DOI: 10.1021/acs.accounts.5b00388] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitroxyl (HNO) is a biological signaling agent that displays distinctive reactivity compared to nitric oxide (NO). As a consequence, these two reactive nitrogen species trigger different physiological responses. Selective detection of HNO over NO has been a challenge for chemists, and several fluorogenic molecular probes have been recently developed with that goal in mind. Common constructs take advantage of the HNO-induced reduction of Cu(II) to Cu(I). The sensing mechanism of such probes relies on the ability of the unpaired electron in a d orbital of the Cu(II) center to quench the fluorescence of a photoemissive ligand by either an electron or energy transfer mechanism. Experimental and theoretical mechanistic studies suggest that proton-coupled electron transfer mediates this process, and careful tuning of the copper coordination environment has led to sensors with optimized selectivity and kinetics. The current optical probes cover the visible and near-infrared regions of the spectrum. This palette of sensors comprises structurally and functionally diverse fluorophores such as coumarin (blue/green emission), boron dipyrromethane (BODIPY, green emission), benzoresorufin (red emission), and dihydroxanthenes (near-infrared emission). Many of these sensors have been successfully applied to detect HNO production in live cells. For example, copper-based optical probes have been used to detect HNO production in live mammalian cells that have been treated with H2S and various nitrosating agents. These studies have established a link between HSNO, the smallest S-nitrosothiol, and HNO. In addition, a near-infrared HNO sensor has been used to perform multicolor/multianalyte microscopy, revealing that exogenously applied HNO elevates the concentration of intracellular mobile zinc. This mobilization of zinc ions is presumably a consequence of nitrosation of cysteine residues in zinc-chelating proteins such as metallothionein. Future challenges for the optical imaging of HNO include devising probes that can detect HNO reversibly, especially because ratiometric imaging can only report equilibrium concentrations when the sensing event is reversible. Another important aspect that needs to be addressed is the creation of probes that can sense HNO in specific subcellular locations. These tools would be useful to identify the organelles in which HNO is produced in mammalian cells and probe the intracellular signaling networks in which this reactive nitrogen species is involved. In addition, near-infrared emitting probes might be applied to detect HNO in thicker specimens, such as acute tissue slices and even live animals, enabling the investigation of the roles of HNO in physiological or pathological conditions in multicellular systems.
Collapse
Affiliation(s)
- Pablo Rivera-Fuentes
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stephen J. Lippard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
46
|
Maret W. Analyzing free zinc(II) ion concentrations in cell biology with fluorescent chelating molecules. Metallomics 2015; 7:202-11. [PMID: 25362967 DOI: 10.1039/c4mt00230j] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Essential metal ions are tightly controlled in biological systems. An understanding of metal metabolism and homeostasis is being developed from quantitative information of the sizes, concentrations, and dynamics of cellular and subcellular metal ion pools. In the case of human zinc metabolism, minimally 24 proteins of two zinc transporter families and a dozen metallothioneins participate in cellular uptake, extrusion, and re-distribution among cellular compartments. Significantly, zinc(ii) ions are now considered signaling ions in intra- and intercellular communication. Such functions require transients of free zinc ions. It is experimentally quite challenging to distinguish zinc that is protein-bound from zinc that is not bound to proteins. Measurement of total zinc is relatively straightforward with analytical techniques such as atomic absorption/emission spectroscopy or inductively coupled plasma mass spectrometry. Total zinc concentrations of human cells are 200-300 μM. In contrast, the pool of non-protein bound zinc is mostly examined with fluorescence microscopy/spectroscopy. There are two widely applied fluorescence approaches, one employing low molecular weight chelating agents ("probes") and the other metal-binding proteins ("sensors"). The protein sensors, such as the CALWY, Zap/ZifCY, and carbonic anhydrase-based sensors, can be genetically encoded and have certain advantages in terms of controlling intracellular concentration, localization, and calibration. When employed correctly, both probes and sensors can establish qualitative differences in free zinc ion concentrations. However, when quantitative information is sought, the assumptions underlying the applications of probes and sensors must be carefully examined and even then measured pools of free zinc ions remain methodologically defined. A consensus is building that the steady-state free zinc ion concentrations in the cytosol are in the picomolar range but there is no consensus on their concentrations in subcellular compartments. Applying the extensive toolbox of available probes/sensors in biological systems requires an understanding of the principles of cellular zinc homeostasis and the chemical biology of the probes and sensors. Regardless of limitations in specificity (for a particular metal ion), selectivity (for a particular metal pool), and sensitivity (detection limit), the technology is making remarkable contributions to imaging zinc with high spatiotemporal resolution in single cells and to defining the biochemical functions of zinc ions in cellular regulation.
Collapse
Affiliation(s)
- Wolfgang Maret
- King's College London, Faculty of Life Sciences and Medicine, Division of Diabetes and Nutritional Sciences and Department of Biochemistry, Metal Metabolism Group, 150 Stamford St., London SE1 9NH, UK.
| |
Collapse
|
47
|
Ryu SY, Huh M, You Y, Nam W. Phosphorescent Zinc Probe for Reversible Turn-On Detection with Bathochromically Shifted Emission. Inorg Chem 2015; 54:9704-14. [DOI: 10.1021/acs.inorgchem.5b00967] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Seung Yeon Ryu
- Department
of Chemistry and Nano Science and ‡Division of Chemical Engineering and Materials
Science, Ewha Womans University, Seoul 120-750, Korea
| | - Mijoung Huh
- Department
of Chemistry and Nano Science and ‡Division of Chemical Engineering and Materials
Science, Ewha Womans University, Seoul 120-750, Korea
| | - Youngmin You
- Department
of Chemistry and Nano Science and ‡Division of Chemical Engineering and Materials
Science, Ewha Womans University, Seoul 120-750, Korea
| | - Wonwoo Nam
- Department
of Chemistry and Nano Science and ‡Division of Chemical Engineering and Materials
Science, Ewha Womans University, Seoul 120-750, Korea
| |
Collapse
|
48
|
Hessels AM, Chabosseau P, Bakker MH, Engelen W, Rutter GA, Taylor KM, Merkx M. eZinCh-2: A Versatile, Genetically Encoded FRET Sensor for Cytosolic and Intraorganelle Zn(2+) Imaging. ACS Chem Biol 2015; 10:2126-34. [PMID: 26151333 PMCID: PMC4577962 DOI: 10.1021/acschembio.5b00211] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Zn(2+) plays essential and diverse roles in numerous cellular processes. To get a better understanding of intracellular Zn(2+) homeostasis and the putative signaling role of Zn(2+), various fluorescent sensors have been developed that allow monitoring of Zn(2+) concentrations in single living cells in real time. Thus far, two families of genetically encoded FRET-based Zn(2+) sensors have been most widely applied, the eCALWY sensors developed by our group and the ZapCY sensors developed by Palmer and co-workers. Both have been successfully used to measure cytosolic free Zn(2+), but distinctly different concentrations have been reported when using these sensors to measure Zn(2+) concentrations in the ER and mitochondria. Here, we report the development of a versatile alternative FRET sensor containing a de novo Cys2His2 binding pocket that was created on the surface of the donor and acceptor fluorescent domains. This eZinCh-2 sensor binds Zn(2+) with a high affinity that is similar to that of eCALWY-4 (Kd = 1 nM at pH 7.1), while displaying a substantially larger change in emission ratio. eZinCh-2 not only provides an attractive alternative for measuring Zn(2+) in the cytosol but was also successfully used for measuring Zn(2+) in the ER, mitochondria, and secretory vesicles. Moreover, organelle-targeted eZinCh-2 can also be used in combination with the previously reported redCALWY sensors to allow multicolor imaging of intracellular Zn(2+) simultaneously in the cytosol and the ER or mitochondria.
Collapse
Affiliation(s)
- Anne M. Hessels
- Laboratory
of Chemical Biology and Institute of Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Pauline Chabosseau
- Section
of Cell Biology and Functional Genomics, Division of Medicine, Imperial College London, London, United Kingdom
| | - Maarten H. Bakker
- Laboratory
of Chemical Biology and Institute of Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Wouter Engelen
- Laboratory
of Chemical Biology and Institute of Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Guy A. Rutter
- Section
of Cell Biology and Functional Genomics, Division of Medicine, Imperial College London, London, United Kingdom
| | - Kathryn M. Taylor
- Breast
Cancer Molecular Pharmacology Group, School of Pharmacy and Pharmaceutical
Sciences, Cardiff University, Cardiff, United Kingdom
| | - Maarten Merkx
- Laboratory
of Chemical Biology and Institute of Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| |
Collapse
|
49
|
Abstract
Zinc is an important micronutrient, essential in the diet to avoid a variety of conditions associated with malnutrition such as diarrhoea and alopecia. Lowered circulating levels of zinc are also found in diabetes mellitus, a condition which affects one in twelve of the adult population and whose treatments consume approximately 10 % of healthcare budgets. Zn2+ ions are essential for a huge range of cellular functions and, in the specialised pancreatic β-cell, for the storage of insulin within the secretory granule. Correspondingly, genetic variants in the SLC30A8 gene, which encodes the diabetes-associated granule-resident Zn2+ transporter ZnT8, are associated with an altered risk of type 2 diabetes. Here, we focus on (i) recent advances in measuring free zinc concentrations dynamically in subcellular compartments, and (ii) studies dissecting the role of intracellular zinc in the control of glucose homeostasis in vitro and in vivo. We discuss the effects on insulin secretion and action of deleting or over-expressing Slc30a8 highly selectively in the pancreatic β-cell, and the role of zinc in insulin signalling. While modulated by genetic variability, healthy levels of dietary zinc, and hence normal cellular zinc homeostasis, are likely to play an important role in the proper release and action of insulin to maintain glucose homeostasis and lower diabetes risk.
Collapse
|
50
|
Kiedrowski L. Neuronal acid-induced [Zn²⁺]i elevations calibrated using the low-affinity ratiometric probe FuraZin-1. J Neurochem 2015; 135:777-86. [PMID: 26263185 DOI: 10.1111/jnc.13282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 08/03/2015] [Accepted: 08/07/2015] [Indexed: 11/30/2022]
Abstract
The experiments were carried out on primary cultures of murine cortical neurons from cryopreserved preparations obtained from embryonic-day-16 fetuses. To calibrate acid-induced intracelluar [Zn(2+) ] ([Zn(2+) ]i ) elevations, a low affinity (Kd = 39 μM at pH 6.1) ratiometric Zn(2+) probe, FuraZin-1, was used. A pHi drop from 7.2 to 6.1 caused [Zn(2+) ]i elevations reaching 2 μM; when the thiol-reactive agent N-ethylmaleimide (NEM) was subsequently applied, [Zn(2+) ]i increased further to 5.6 μM; analogous acid- and NEM-induced [Zn(2+) ]i elevations could also be detected but not calibrated, using the high affinity Zn(2+) probe FluoZin-3. The data indicate that NEM causes Zn(2+) release from ligands that chelate Zn(2+) at pH 6.1. ATP could also chelate Zn(2+) at pH 6.1 because its pKa is about 6.8. Therefore, it was tested whether an ATP depletion affects the acid-induced [Zn(2+) ]i elevations. The ATP depletion was induced by inhibiting mitochondrial and glycolytic ATP production. Interestingly, an almost complete ATP depletion (confirmed using a luciferin/luciferase assay) failed to affect the acid-induced [Zn(2+) ]i increases. These data suggest that the total amount of Zn(2+) accumulated in intracellular ATP-dependent stores (Zn(2+) -ATP complexes and organelles that accumulate Zn(2+) in an ATP-dependent manner) is negligible compared to the amount of Zn(2+) accumulated in the acid-sensitive intracellular ligands. In vitro, upon acidification, Zn(2+) -cysteine complexes release Zn(2+) and ATP chelates the released Zn(2+) . However, in vivo (cultured neurons), an ATP depletion failed to enhance acid-induced [Zn(2+) ]i elevations. These [Zn(2+) ]i elevations were calibrated using a low affinity ratiometric probe FuraZin-1; they reached 2 µM levels and increased to 5 µM when a thiol-reactive agent, N-ethylmaleimide, compromised Zn(2+) binding by cysteines.
Collapse
Affiliation(s)
- Lech Kiedrowski
- The Psychiatric Institute, Departments of Psychiatry and Pharmacology, The University of Illinois at Chicago, Chicago, Illinois, USA
| |
Collapse
|