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Jensen GC, Janis MK, Nguyen HN, David OW, Zastrow ML. Fluorescent Protein-Based Sensors for Detecting Essential Metal Ions across the Tree of Life. ACS Sens 2024; 9:1622-1643. [PMID: 38587931 PMCID: PMC11073808 DOI: 10.1021/acssensors.3c02695] [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] [Indexed: 04/10/2024]
Abstract
Genetically encoded fluorescent metal ion sensors are powerful tools for elucidating metal dynamics in living systems. Over the last 25 years since the first examples of genetically encoded fluorescent protein-based calcium indicators, this toolbox of probes has expanded to include other essential and non-essential metal ions. Collectively, these tools have illuminated fundamental aspects of metal homeostasis and trafficking that are crucial to fields ranging from neurobiology to human nutrition. Despite these advances, much of the application of metal ion sensors remains limited to mammalian cells and tissues and a limited number of essential metals. Applications beyond mammalian systems and in vivo applications in living organisms have primarily used genetically encoded calcium ion sensors. The aim of this Perspective is to provide, with the support of historical and recent literature, an updated and critical view of the design and use of fluorescent protein-based sensors for detecting essential metal ions in various organisms. We highlight the historical progress and achievements with calcium sensors and discuss more recent advances and opportunities for the detection of other essential metal ions. We also discuss outstanding challenges in the field and directions for future studies, including detecting a wider variety of metal ions, developing and implementing a broader spectral range of sensors for multiplexing experiments, and applying sensors to a wider range of single- and multi-species biological systems.
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Affiliation(s)
- Gary C Jensen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Makena K Janis
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Hazel N Nguyen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Ogonna W David
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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2
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Lin Z, Zhang X, Nandi P, Lin Y, Wang L, Chu YS, Paape T, Yang Y, Xiao X, Liu Q. Correlative single-cell hard X-ray computed tomography and X-ray fluorescence imaging. Commun Biol 2024; 7:280. [PMID: 38448784 PMCID: PMC10917812 DOI: 10.1038/s42003-024-05950-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 02/21/2024] [Indexed: 03/08/2024] Open
Abstract
X-ray computed tomography (XCT) and X-ray fluorescence (XRF) imaging are two non-invasive imaging techniques to study cellular structures and chemical element distributions, respectively. However, correlative X-ray computed tomography and fluorescence imaging for the same cell have yet to be routinely realized due to challenges in sample preparation and X-ray radiation damage. Here we report an integrated experimental and computational workflow for achieving correlative multi-modality X-ray imaging of a single cell. The method consists of the preparation of radiation-resistant single-cell samples using live-cell imaging-assisted chemical fixation and freeze-drying procedures, targeting and labeling cells for correlative XCT and XRF measurement, and computational reconstruction of the correlative and multi-modality images. With XCT, cellular structures including the overall structure and intracellular organelles are visualized, while XRF imaging reveals the distribution of multiple chemical elements within the same cell. Our correlative method demonstrates the feasibility and broad applicability of using X-rays to understand cellular structures and the roles of chemical elements and related proteins in signaling and other biological processes.
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Affiliation(s)
- Zihan Lin
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Xiao Zhang
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Purbasha Nandi
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Yuewei Lin
- Computational Science Initiative, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Liguo Wang
- Laboratory for BioMolecular Structure, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Yong S Chu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Timothy Paape
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
- U.S. Department of Agriculture's Agricultural Research Service at Children's Nutrition Research Center, Houston, TX, 77030, USA
| | - Yang Yang
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - Xianghui Xiao
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - Qun Liu
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA.
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3
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Tamrakar A, Kumar P, Garg N, Luis SV, Pandey MD. Intracellular Zn(II) induced turn-on fluorescence of an L-phenylalanine-derived pseudopeptide. Org Biomol Chem 2023; 21:8823-8828. [PMID: 37906437 DOI: 10.1039/d3ob01337e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
A C2 symmetric L-phenylalanine-derived pseudopeptide has been synthesized for selective and sensitive recognition of Zn(II) ions in aqueous-organic media. The pseudopeptidic probes exhibit intracellular Zn(II) ion-sensing capabilities as demonstrated via live-cell fluorescence studies on RAW264.7 cells. Hence, we present a bioinspired pseudopeptide for potential biological applications involving intracellular Zn(II) ion detection.
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Affiliation(s)
- Arpna Tamrakar
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi-221005, India.
| | - Praveen Kumar
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India
| | - Neha Garg
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India
| | - Santiago V Luis
- Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Av. SosBaynat, s/n, E-12071 Castellón, Spain
| | - Mrituanjay D Pandey
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi-221005, India.
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4
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Jensen GC, Janis MK, Jara J, Abbasi N, Zastrow ML. Zinc-Induced Fluorescence Turn-On in Native and Mutant Phycoerythrobilin-Binding Orange Fluorescent Proteins. Biochemistry 2023; 62:2828-2840. [PMID: 37699411 PMCID: PMC11057272 DOI: 10.1021/acs.biochem.3c00183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Cyanobacteriochrome (CBCR)-derived fluorescent proteins are a class of reporters that can bind bilin cofactors and fluoresce across the ultraviolet to the near-infrared spectrum. Derived from phytochrome-related photoreceptor proteins in cyanobacteria, many of these proteins use a single small GAF domain to autocatalytically bind a bilin and fluoresce. The second GAF domain of All1280 (All1280g2) from Nostoc sp. PCC7120 is a DXCF motif-containing protein that exhibits blue-light-responsive photochemistry when bound to its native cofactor, phycocyanobilin. All1280g2 can also bind non-photoswitching phycoerythrobilin (PEB), resulting in a highly fluorescent protein. Given the small size, high quantum yield, and that unlike green fluorescent proteins, bilin-binding proteins can be used in anaerobic organisms, the orange fluorescent All1280g2-PEB protein is a promising platform for designing new genetically encoded metal ion sensors. Here, we show that All1280g2-PEB undergoes a ∼5-fold reversible zinc-induced fluorescence enhancement with a blue-shifted emission maximum (572 to 517 nm), which is not observed for a related PEB-bound GAF from Synechocystis sp. PCC6803 (Slr1393g3). Zn2+ significantly enhances All1280g2-PEB fluorescence across a biologically relevant pH range from 6.0 to 9.0, with pH-dependent dissociation constants from 1 μM to ∼20-80 nM. Site-directed mutants aiming to sterically decrease and increase access to PEB show a decreased and similar amount of zinc-induced fluorescence enhancement. Mutation of the cysteine residue within the DXCF motif to alanine abolishes the zinc-induced fluorescence enhancement. Collectively, these results support the presence of a unique fluorescence-enhancing Zn2+ binding site in All1280g2-PEB likely involving coordination to the bilin cofactor and requiring a nearby cysteine residue.
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Affiliation(s)
- Gary C Jensen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Makena K Janis
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Jazzmin Jara
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Nasir Abbasi
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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5
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Feng Y, Gao C, Xie D, Liu L, Chen B, Liu S, Yang H, Gao Z, Wilson DA, Tu Y, Peng F. Directed Neural Stem Cells Differentiation via Signal Communication with Ni-Zn Micromotors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2301736. [PMID: 37402480 DOI: 10.1002/adma.202301736] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/06/2023] [Accepted: 07/02/2023] [Indexed: 07/06/2023]
Abstract
Neural stem cells (NSCs), with the capability of self-renewal, differentiation, and environment modulation, are considered promising for stroke, brain injury therapy, and neuron regeneration. Activation of endogenous NSCs, is attracting increasing research enthusiasm, which avoids immune rejection and ethical issues of exogenous cell transplantation. Yet, how to induce directed growth and differentiation in situ remain a major challenge. In this study, a pure water-driven Ni-Zn micromotor via a self-established electric-chemical field is proposed. The micromotors can be magnetically guided and precisely approach target NSCs. Through the electric-chemical field, bioelectrical signal exchange and communication with endogenous NSCs are allowed, thus allowing for regulated proliferation and directed neuron differentiation in vivo. Therefore, the Ni-Zn micromotor provides a platform for controlling cell fate via a self-established electrochemical field and targeted activation of endogenous NSCs.
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Affiliation(s)
- Ye Feng
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Chao Gao
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Dazhi Xie
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Lu Liu
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, P. R. China
| | - Bin Chen
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Suyi Liu
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Haihong Yang
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Zhan Gao
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Daniela A Wilson
- Institute for Molecules and Materials, Radboud University, Nijmegen, 6525 AJ, The Netherlands
| | - Yingfeng Tu
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, P. R. China
| | - Fei Peng
- School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
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6
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Sadoine M, De Michele R, Župunski M, Grossmann G, Castro-Rodríguez V. Monitoring nutrients in plants with genetically encoded sensors: achievements and perspectives. PLANT PHYSIOLOGY 2023; 193:195-216. [PMID: 37307576 PMCID: PMC10469547 DOI: 10.1093/plphys/kiad337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 06/14/2023]
Abstract
Understanding mechanisms of nutrient allocation in organisms requires precise knowledge of the spatiotemporal dynamics of small molecules in vivo. Genetically encoded sensors are powerful tools for studying nutrient distribution and dynamics, as they enable minimally invasive monitoring of nutrient steady-state levels in situ. Numerous types of genetically encoded sensors for nutrients have been designed and applied in mammalian cells and fungi. However, to date, their application for visualizing changing nutrient levels in planta remains limited. Systematic sensor-based approaches could provide the quantitative, kinetic information on tissue-specific, cellular, and subcellular distributions and dynamics of nutrients in situ that is needed for the development of theoretical nutrient flux models that form the basis for future crop engineering. Here, we review various approaches that can be used to measure nutrients in planta with an overview over conventional techniques, as well as genetically encoded sensors currently available for nutrient monitoring, and discuss their strengths and limitations. We provide a list of currently available sensors and summarize approaches for their application at the level of cellular compartments and organelles. When used in combination with bioassays on intact organisms and precise, yet destructive analytical methods, the spatiotemporal resolution of sensors offers the prospect of a holistic understanding of nutrient flux in plants.
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Affiliation(s)
- Mayuri Sadoine
- Institute of Cell and Interaction Biology, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Roberto De Michele
- Institute of Biosciences and Bioresources, National Research Council of Italy, Palermo 90129, Italy
| | - Milan Župunski
- Institute of Cell and Interaction Biology, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Guido Grossmann
- Institute of Cell and Interaction Biology, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
- Cluster of Excellence on Plant Sciences, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Vanessa Castro-Rodríguez
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Málaga 29071, Spain
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7
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Jensen GC, Janis MK, Jara J, Abbasi N, Zastrow ML. Zinc-Induced Fluorescence Turn-on in Native and Mutant Phycoerythrobilin-Binding Orange Fluorescent Proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.11.552977. [PMID: 37609204 PMCID: PMC10441388 DOI: 10.1101/2023.08.11.552977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Cyanobacteriochrome (CBCR)-derived fluorescent proteins are a class of reporters that can bind bilin cofactors and fluoresce across the ultraviolet to near-infrared spectrum. Derived from phytochrome-related photoreceptor proteins in cyanobacteria, many of these proteins use a single small GAF domain to autocatalytically bind a bilin and fluoresce. The second GAF domain of All1280 from Nostoc sp. PCC7120 is a DXCF motif-containing protein that exhibits blue light-responsive photochemistry when bound to its native cofactor, phycocyanobilin. GAF2 can also bind non-photoswitching phycoerythrobilin (PEB), resulting in a highly fluorescent protein. Given the small size, high quantum yield, and that, unlike green fluorescent proteins, bilin-binding proteins can be used in anaerobic organisms, the orange fluorescent GAF2-PEB protein is a promising platform for designing new genetically encoded metal ion sensors. Here we show that GAF2-PEB undergoes a ∼5-fold reversible zinc-induced fluorescence enhancement with blue-shifted emission maximum (572 to 517 nm), which is not observed for a related PEB-bound GAF from Synechocystis sp. PCC6803 (Slr1393g3). Zn 2+ significantly enhances GAF2-PEB fluorescence across a biologically relevant pH range from 6.0-9.0 and with pH-dependent µM to nM dissociation constants. Site-directed mutants aiming to sterically decrease and increase access to PEB show a decreased and similar amount of zinc-induced fluorescence enhancement, respectively. Mutation of the cysteine residue within the DXCF motif to alanine abolishes zinc-induced fluorescence enhancement. Collectively, these results support the presence of a fluorescence enhancing Zn 2+ binding site in GAF2-PEB likely involving coordination to the bilin cofactor and requiring a nearby cysteine residue.
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Affiliation(s)
- Gary C. Jensen
- Department of Chemistry, University of Houston, 3585 Cullen Blvd, Houston, TX, 77204 (USA)
| | - Makena K. Janis
- Department of Chemistry, University of Houston, 3585 Cullen Blvd, Houston, TX, 77204 (USA)
| | - Jazzmin Jara
- Department of Chemistry, University of Houston, 3585 Cullen Blvd, Houston, TX, 77204 (USA)
| | - Nasir Abbasi
- Department of Chemistry, University of Houston, 3585 Cullen Blvd, Houston, TX, 77204 (USA)
| | - Melissa L. Zastrow
- Department of Chemistry, University of Houston, 3585 Cullen Blvd, Houston, TX, 77204 (USA)
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8
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Minckley TF, Salvagio LA, Fudge DH, Verhey K, Markus SM, Qin Y. Zn2+ decoration of microtubules arrests axonal transport and displaces tau, doublecortin, and MAP2C. J Cell Biol 2023; 222:e202208121. [PMID: 37326602 PMCID: PMC10276529 DOI: 10.1083/jcb.202208121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 03/31/2023] [Accepted: 05/11/2023] [Indexed: 06/17/2023] Open
Abstract
Intracellular Zn2+ concentrations increase via depolarization-mediated influx or intracellular release, but the immediate effects of Zn2+ signals on neuron function are not fully understood. By simultaneous recording of cytosolic Zn2+ and organelle motility, we find that elevated Zn2+ (IC50 ≈ 5-10 nM) reduces both lysosomal and mitochondrial motility in primary rat hippocampal neurons and HeLa cells. Using live-cell confocal microscopy and in vitro single-molecule TIRF imaging, we reveal that Zn2+ inhibits activity of motor proteins (kinesin and dynein) without disrupting their microtubule binding. Instead, Zn2+ directly binds to microtubules and selectively promotes detachment of tau, DCX, and MAP2C, but not MAP1B, MAP4, MAP7, MAP9, or p150glued. Bioinformatic predictions and structural modeling show that the Zn2+ binding sites on microtubules partially overlap with the microtubule binding sites of tau, DCX, dynein, and kinesin. Our results reveal that intraneuronal Zn2+ regulates axonal transport and microtubule-based processes by interacting with microtubules.
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Affiliation(s)
- Taylor F. Minckley
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | | | - Dylan H. Fudge
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Kristen Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Steven M. Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Yan Qin
- Department of Biological Sciences, University of Denver, Denver, CO, USA
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9
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Dorward AM, Stewart AJ, Pitt SJ. The role of Zn2+ in shaping intracellular Ca2+ dynamics in the heart. J Gen Physiol 2023; 155:e202213206. [PMID: 37326614 PMCID: PMC10276528 DOI: 10.1085/jgp.202213206] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 04/18/2023] [Accepted: 05/22/2023] [Indexed: 06/17/2023] Open
Abstract
Increasing evidence suggests that Zn2+ acts as a second messenger capable of transducing extracellular stimuli into intracellular signaling events. The importance of Zn2+ as a signaling molecule in cardiovascular functioning is gaining traction. In the heart, Zn2+ plays important roles in excitation-contraction (EC) coupling, excitation-transcription coupling, and cardiac ventricular morphogenesis. Zn2+ homeostasis in cardiac tissue is tightly regulated through the action of a combination of transporters, buffers, and sensors. Zn2+ mishandling is a common feature of various cardiovascular diseases. However, the precise mechanisms controlling the intracellular distribution of Zn2+ and its variations during normal cardiac function and during pathological conditions are not fully understood. In this review, we consider the major pathways by which the concentration of intracellular Zn2+ is regulated in the heart, the role of Zn2+ in EC coupling, and discuss how Zn2+ dyshomeostasis resulting from altered expression levels and efficacy of Zn2+ regulatory proteins are key drivers in the progression of cardiac dysfunction.
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Affiliation(s)
- Amy M. Dorward
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Alan J. Stewart
- School of Medicine, University of St Andrews, St Andrews, UK
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10
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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.
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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.
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11
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Hübner C, Keil C, Jürgensen A, Barthel L, Haase H. Comparison of Three Low-Molecular-Weight Fluorescent Probes for Measuring Free Zinc Levels in Cultured Mammary Cells. Nutrients 2023; 15:nu15081873. [PMID: 37111093 PMCID: PMC10141224 DOI: 10.3390/nu15081873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/31/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
Free zinc is a critical regulator in signal transduction and affects many cellular processes relevant to cancer, including proliferation and cell death. Acting as a second messenger, altered free intracellular zinc has fundamental effects on regulating enzymes such as phosphatases and caspases. Therefore, the determination of free intracellular zinc levels is essential to assess its influence on the signaling processes involved in cancer development and progression. In this study, we compare three low-molecular-weight fluorescent probes, ZinPyr-1, TSQ, and FluoZin-3, for measuring free zinc in different mammary cell lines (MCF10A, MCF7, T47D, and MDA-MB-231). In summary, ZinPyr-1 is the most suitable probe for free Zn quantification. It responds well to calibration based on minimal fluorescence in the presence of the chelator TPEN (N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine) and maximal fluorescence by saturation with ZnSO4, resulting in the detection of free intracellular zinc in breast cancer subtypes ranging from 0.62 nM to 1.25 nM. It also allows for measuring the zinc fluxes resulting from incubation with extracellular zinc, showing differences in the zinc uptake between the non-malignant MCF10A cell line and the other cell lines. Finally, ZinPyr-1 enables the monitoring of sub-cellular distributions by fluorescence microscopy. Altogether, these properties provide a basis for the further exploration of free zinc in order to realize its full potential as a possible biomarker or even therapeutic target in breast cancer.
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Affiliation(s)
- Christopher Hübner
- Department of Food Chemistry and Toxicology, Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Claudia Keil
- Department of Food Chemistry and Toxicology, Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Anton Jürgensen
- Department of Food Chemistry and Toxicology, Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Lars Barthel
- Department of Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Hajo Haase
- Department of Food Chemistry and Toxicology, Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
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12
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Wu T, Kumar M, Zhang J, Zhao S, Drobizhev M, McCollum M, Anderson CT, Wang Y, Pokorny A, Tian X, Zhang Y, Tzounopoulos T, Ai HW. A genetically encoded far-red fluorescent indicator for imaging synaptically released Zn 2. SCIENCE ADVANCES 2023; 9:eadd2058. [PMID: 36857451 PMCID: PMC9977179 DOI: 10.1126/sciadv.add2058] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Synaptic zinc ion (Zn2+) has emerged as a key neuromodulator in the brain. However, the lack of research tools for directly tracking synaptic Zn2+ in the brain of awake animals hinders our rigorous understanding of the physiological and pathological roles of synaptic Zn2+. In this study, we developed a genetically encoded far-red fluorescent indicator for monitoring synaptic Zn2+ dynamics in the nervous system. Our engineered far-red fluorescent indicator for synaptic Zn2+ (FRISZ) displayed a substantial Zn2+-specific turn-on response and low-micromolar affinity. We genetically anchored FRISZ to the mammalian extracellular membrane via a transmembrane (TM) ⍺ helix and characterized the resultant FRISZ-TM construct at the mammalian cell surface. We used FRISZ-TM to image synaptic Zn2+ in the auditory cortex in acute brain slices and awake mice in response to electric and sound stimuli, respectively. Thus, this study establishes a technology for studying the roles of synaptic Zn2+ in the nervous system.
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Affiliation(s)
- Tianchen Wu
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Manoj Kumar
- Department of Otolaryngology, Pittsburgh Hearing Research Center, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Jing Zhang
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Shengyu Zhao
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Mikhail Drobizhev
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT 59717-384, USA
| | - Mason McCollum
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Charles T. Anderson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Ying Wang
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA
| | - Antje Pokorny
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA
| | - Xiaodong Tian
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yiyu Zhang
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Thanos Tzounopoulos
- Department of Otolaryngology, Pittsburgh Hearing Research Center, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Hui-wang Ai
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
- The UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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13
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Jarosova R, Woolfolk SK, Martinez-Rivera N, Jaeschke MW, Rosa-Molinar E, Tamerler C, Johnson MA. Spatiotemporal Imaging of Zinc Ions in Zebrafish Live Brain Tissue Enabled by Fluorescent Bionanoprobes. Molecules 2023; 28:molecules28052260. [PMID: 36903504 PMCID: PMC10005619 DOI: 10.3390/molecules28052260] [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: 12/19/2022] [Revised: 02/11/2023] [Accepted: 02/19/2023] [Indexed: 03/05/2023] Open
Abstract
The zebrafish is a powerful model organism to study the mechanisms governing transition metal ions within whole brain tissue. Zinc is one of the most abundant metal ions in the brain, playing a critical pathophysiological role in neurodegenerative diseases. The homeostasis of free, ionic zinc (Zn2+) is a key intersection point in many of these diseases, including Alzheimer's disease and Parkinson's disease. A Zn2+ imbalance can eventuate several disturbances that may lead to the development of neurodegenerative changes. Therefore, compact, reliable approaches that allow the optical detection of Zn2+ across the whole brain would contribute to our current understanding of the mechanisms that underlie neurological disease pathology. We developed an engineered fluorescence protein-based nanoprobe that can spatially and temporally resolve Zn2+ in living zebrafish brain tissue. The self-assembled engineered fluorescence protein on gold nanoparticles was shown to be confined to defined locations within the brain tissue, enabling site specific studies, compared to fluorescent protein-based molecular tools, which diffuse throughout the brain tissue. Two-photon excitation microscopy confirmed the physical and photometrical stability of these nanoprobes in living zebrafish (Danio rerio) brain tissue, while the addition of Zn2+ quenched the nanoprobe fluorescence. Combining orthogonal sensing methods with our engineered nanoprobes will enable the study of imbalances in homeostatic Zn2+ regulation. The proposed bionanoprobe system offers a versatile platform to couple metal ion specific linkers and contribute to the understanding of neurological diseases.
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Affiliation(s)
- Romana Jarosova
- Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, KS 66045, USA
- UNESCO Laboratory of Environmental Electrochemistry, Department of Analytical Chemistry, Charles University, 12843 Prague 2, Czech Republic
| | - Sarah K. Woolfolk
- Institute for Bioengineering Research, University of Kansas, Lawrence, KS 66045, USA
- Bioengineering Program, University of Kansas, Lawrence, KS 66045, USA
| | - Noraida Martinez-Rivera
- Microscopy and Analytical Imaging Research Resource Core Laboratory, University of Kansas, Lawrence, KS 66045, USA
| | - Mathew W. Jaeschke
- Institute for Bioengineering Research, University of Kansas, Lawrence, KS 66045, USA
- Department of Mechanical Engineering, University of Kansas, Lawrence, KS 66045, USA
| | - Eduardo Rosa-Molinar
- Microscopy and Analytical Imaging Research Resource Core Laboratory, University of Kansas, Lawrence, KS 66045, USA
- Department of Pharmacology & Toxicology, University of Kansas, Lawrence, KS 66045, USA
| | - Candan Tamerler
- Institute for Bioengineering Research, University of Kansas, Lawrence, KS 66045, USA
- Bioengineering Program, University of Kansas, Lawrence, KS 66045, USA
- Department of Mechanical Engineering, University of Kansas, Lawrence, KS 66045, USA
- Correspondence: (M.A.J.); (C.T.)
| | - Michael A. Johnson
- Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, KS 66045, USA
- Correspondence: (M.A.J.); (C.T.)
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14
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Goldberg JM, Lippard SJ. Mobile zinc as a modulator of sensory perception. FEBS Lett 2023; 597:151-165. [PMID: 36416529 PMCID: PMC10108044 DOI: 10.1002/1873-3468.14544] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/24/2022]
Abstract
Mobile zinc is an abundant transition metal ion in the central nervous system, with pools of divalent zinc accumulating in regions of the brain engaged in sensory perception and memory formation. Here, we present essential tools that we developed to interrogate the role(s) of mobile zinc in these processes. Most important are (a) fluorescent sensors that report the presence of mobile zinc and (b) fast, Zn-selective chelating agents for measuring zinc flux in animal tissue and live animals. The results of our studies, conducted in collaboration with neuroscientist experts, are presented for sensory organs involved in hearing, smell, vision, and learning and memory. A general principle emerging from these studies is that the function of mobile zinc in all cases appears to be downregulation of the amplitude of the response following overstimulation of the respective sensory organs. Possible consequences affecting human behavior are presented for future investigations in collaboration with interested behavioral scientists.
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Affiliation(s)
| | - Stephen J Lippard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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15
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Dischler AM, Maslar D, Zhang C, Qin Y. Development and Characterization of a Red Fluorescent Protein-Based Sensor RZnP1 for the Detection of Cytosolic Zn 2. ACS Sens 2022; 7:3838-3845. [PMID: 36508266 DOI: 10.1021/acssensors.2c01774] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fluorescent sensors have been developed to record Zn2+ dynamics and measure Zn2+ concentrations within the cell. Most previous efforts on developing single-wavelength sensors are focused on green sensors. Here, we engineer a genetically encoded, single red fluorescent protein-based Zn2+ sensor, Red Zinc Probe (RZnP1), which can detect intracellular concentrations of Zn2+. RZnP1 demonstrates a sensitive response to cytosolic Zn2+ (Kd = 438 pM), decent brightness (quantum yield (QY) = 0.15), good in situ dynamic range (Fmax/Fmin = 4.0), and specificity for Zn2+ over other biologically relevant metal cations. RZnP1 offers a way to image Zn2+ with multiple intracellular ions in tandem. We demonstrate the simultaneous recording of Zn2+ and Ca2+ using RZnP1 alongside the Ca2+ sensor GCaMP5G in HeLa cells. We also use RZnP1 with mito-GZnP2, a green fluorescent protein (GFP)-based mitochondrial Zn2+ sensor, to track Zn2+ dynamics in the cytosol and mitochondria concurrently in rat primary neuron culture. Our work not only expands the toolbox of Zn2+ sensors but also demonstrates techniques for imaging Zn2+ dynamics along with other cations and between multiple subcellular compartments simultaneously.
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Affiliation(s)
- Anna M Dischler
- Department of Biological Sciences, University of Denver, Denver, Colorado80210, United States
| | - Drew Maslar
- Department of Biological Sciences, University of Denver, Denver, Colorado80210, United States
| | - Chen Zhang
- Department of Biological Sciences, University of Denver, Denver, Colorado80210, United States
| | - Yan Qin
- Department of Biological Sciences, University of Denver, Denver, Colorado80210, United States
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16
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Zou W, Nguyen HN, Zastrow ML. Mutant Flavin-Based Fluorescent Protein Sensors for Detecting Intracellular Zinc and Copper in Escherichia coli. ACS Sens 2022; 7:3369-3378. [PMID: 36282086 PMCID: PMC9888404 DOI: 10.1021/acssensors.2c01376] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Flavin-based fluorescent proteins (FbFPs) are a class of fluorescent reporters that undergo oxygen-independent fluorophore incorporation, which is an important advantage over green fluorescent proteins (GFPs) and mFruits. A FbFP derived from Chlamydomonas reinhardtii (CreiLOV) is a promising platform for designing new metal sensors. Some FbFPs are intrinsically quenched by metal ions, but the question of where metals bind and how to tune metal affinity has not been addressed. We used site-directed mutagenesis of CreiLOV to probe a hypothesized copper(II) binding site that led to fluorescence quenching. Most mutations changed the fluorescence quenching level, supporting the proposed site. One key mutation introducing a second cysteine residue in place of asparagine (CreiLOVN41C) significantly altered metal affinity and selectivity, yielding a zinc sensor. The fluorescence intensity and lifetime of CreiLOVN41C were reversibly quenched by Zn2+ ions with a biologically relevant affinity (apparent dissociation constant, Kd, of 1 nM). Copper quenching of CreiLOVN41C was retained but with several orders of magnitude higher affinity than CreiLOV (Kd = 0.066 fM for Cu2+, 5.4 fM for Cu+) and partial reversibility. We also show that CreiLOVN41C is an excellent intensity- and lifetime-based zinc sensor in aerobic and anaerobic live bacterial cells. Zn2+-induced fluorescence quenching is reversible over several cycles in Escherichia coli cell suspensions and can be imaged by fluorescence microscopy. CreiLOVN41C is a novel oxygen-independent metal sensor that significantly expands the current fluorescent protein-based toolbox of metal sensors and will allow for studies of anaerobic and low oxygen systems previously precluded by the use of oxygen-dependent GFPs.
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Affiliation(s)
- Wenping Zou
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Hazel N. Nguyen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L. Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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17
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Peng W, Maydew CC, Kam H, Lynd JK, Tutol JN, Phelps SM, Abeyrathna S, Meloni G, Dodani SC. Discovery of a monomeric green fluorescent protein sensor for chloride by structure-guided bioinformatics. Chem Sci 2022; 13:12659-12672. [PMID: 36519056 PMCID: PMC9645410 DOI: 10.1039/d2sc03903f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 10/05/2022] [Indexed: 11/21/2022] Open
Abstract
Chloride is an essential anion for all forms of life. Beyond electrolyte balance, an increasing body of evidence points to new roles for chloride in normal physiology and disease. Over the last two decades, this understanding has been advanced by chloride-sensitive fluorescent proteins for imaging applications in living cells. To our surprise, these sensors have primarily been engineered from the green fluorescent protein (GFP) found in the jellyfish Aequorea victoria. However, the GFP family has a rich sequence space that could already encode for new sensors with desired properties, thereby minimizing protein engineering efforts and accelerating biological applications. To efficiently sample this space, we present and validate a stepwise bioinformatics strategy focused first on the chloride binding pocket and second on a monomeric oligomerization state. Using this, we identified GFPxm163 from GFPxm found in the jellyfish Aequorea macrodactyla. In vitro characterization shows that the binding of chloride as well as bromide, iodide, and nitrate rapidly tunes the ground state chromophore equilibrium from the phenolate to the phenol state generating a pH-dependent, turn-off fluorescence response. Furthermore, live-cell fluorescence microscopy reveals that GFPxm163 provides a reversible, yet indirect readout of chloride transport via iodide exchange. With this demonstration, we anticipate that the pairing of bioinformatics with protein engineering methods will provide an efficient methodology to discover and design new chloride-sensitive fluorescent proteins for cellular applications.
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Affiliation(s)
- Weicheng Peng
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
- Department of Biological Sciences, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Caden C Maydew
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Hiu Kam
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Jacob K Lynd
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Jasmine N Tutol
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Shelby M Phelps
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Sameera Abeyrathna
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Gabriele Meloni
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
| | - Sheel C Dodani
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson 75080 Texas USA
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18
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Assunção AGL. The F-bZIP-regulated Zn deficiency response in land plants. PLANTA 2022; 256:108. [PMID: 36348172 PMCID: PMC9643250 DOI: 10.1007/s00425-022-04019-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 10/22/2022] [Indexed: 06/16/2023]
Abstract
This review describes zinc sensing and transcriptional regulation of the zinc deficiency response in Arabidopsis, and discusses how their evolutionary conservation in land plants facilitates translational approaches for improving the Zn nutritional value of crop species. Zinc is an essential micronutrient for all living organisms due to its presence in a large number of proteins, as a structural or catalytic cofactor. In plants, zinc homeostasis mechanisms comprise uptake from soil, transport and distribution throughout the plant to provide adequate cellular zinc availability. Here, I discuss the transcriptional regulation of the response to zinc deficiency and the zinc sensing mechanisms in Arabidopsis, and their evolutionary conservation in land plants. The Arabidopsis F-group basic region leucine-zipper (F-bZIP) transcription factors bZIP19 and bZIP23 function simultaneously as sensors of intracellular zinc status, by direct binding of zinc ions, and as the central regulators of the zinc deficiency response, with their target genes including zinc transporters from the ZRT/IRT-like Protein (ZIP) family and nicotianamine synthase enzymes that produce the zinc ligand nicotianamine. I note that this relatively simple mechanism of zinc sensing and regulation, together with the evolutionary conservation of F-bZIP transcription factors across land plants, offer important research opportunities. One of them is to use the F-bZIP-regulated zinc deficiency response as a tractable module for evolutionary and comparative functional studies. Another research opportunity is translational research in crop plants, modulating F-bZIP activity as a molecular switch to enhance zinc accumulation. This should become a useful plant-based solution to alleviate effects of zinc deficiency in soils, which impact crop production and crop zinc content, with consequences for human nutrition globally.
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Affiliation(s)
- Ana G L Assunção
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark.
- CIBIO-InBIO, Research Centre in Biodiversity and Genetic Resources, University of Porto, 4485-661, Vairão, Portugal.
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19
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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: 9] [Impact Index Per Article: 4.5] [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.
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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
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20
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López-Solís L, Companys E, Puy J, Blindauer CA, Galceran J. Direct determination of free Zn concentration in samples of biological interest. Anal Chim Acta 2022; 1229:340195. [DOI: 10.1016/j.aca.2022.340195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/25/2022] [Accepted: 07/19/2022] [Indexed: 11/01/2022]
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21
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Zhao H, Zastrow ML. Transition Metals Induce Quenching of Monomeric Near-Infrared Fluorescent Proteins. Biochemistry 2022; 61:494-504. [PMID: 35289592 DOI: 10.1021/acs.biochem.1c00705] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transition metals such as zinc and copper are essential in numerous life processes, and both deficiency and toxic overload of these metals are associated with various diseases. Fluorescent metal sensors are powerful tools for studying the roles of metal ions in the physiology and pathology of biological systems. Green fluorescent protein (GFP) and its derivatives are highly utilized for protein-based sensor design, but application to anaerobic systems is limited because these proteins require oxygen to become fluorescent. Bacteriophytochrome-based monomeric near-infrared fluorescent proteins (miRFPs) covalently bind a bilin cofactor, which can be added exogenously for anaerobic cells. miRFPs can also have emission wavelengths extending to >700 nm, which is valuable for imaging applications. Here, we evaluated the suitability of miRFP670 and miRFP709 as platforms for single fluorescent protein metal ion sensors. We found that divalent metal ions like Zn2+, Co2+, Ni2+, and Cu2+ can quench from ∼6-20% (Zn2+, Co2+, and Ni2+) and up to nearly 90% (Cu2+) of the fluorescence intensity of pure miRFPs and have similar impacts in live Escherichia coli cells expressing miRFPs. The presence of a 6× histidine tag for purification influences metal quenching, but significant Cu2+-induced quenching and a picomolar binding affinity are retained in the absence of the His6 tag in both cuvettes and live bacterial cells. By comparing the Cu2+ and Cu+-induced quenching results for miRFP670 and miRFP709 and through examining absorption spectra and previously reported crystal structures, we propose a surface metal binding site near the biliverdin IXα chromophore.
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Affiliation(s)
- Haowen Zhao
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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22
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Clemens S. The cell biology of zinc. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:1688-1698. [PMID: 34727160 DOI: 10.1093/jxb/erab481] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
Nearly 10% of all plant proteins belong to the zinc (Zn) proteome. They require Zn either for catalysis or as a structural element. Most of the protein-bound Zn in eukaryotic cells is found in the cytosol. The fundamental differences between transition metal cations in the stability of their complexes with organic ligands, as described by the Irving-Williams series, necessitate buffering of cytosolic Zn (the 'free Zn' pool) in the picomolar range (i.e. ~6 orders of magnitude lower than the total cellular concentration). Various metabolites and peptides, including nicotianamine, glutathione, and phytochelatins, serve as Zn buffers. They are hypothesized to supply Zn to enzymes, transporters, or the recently identified sensor proteins. Zn2+ acquisition is mediated by ZRT/IRT-like proteins. Metal tolerance proteins transport Zn2+ into vacuoles and the endoplasmic reticulum, the major Zn storage sites. Heavy metal ATPase-dependent efflux of Zn2+ is another mechanism to control cytosolic Zn. Spatially controlled Zn2+ influx or release from intracellular stores would result in dynamic modulation of cellular Zn pools, which may directly influence protein-protein interactions or the activities of enzymes involved in signaling cascades. Possible regulatory roles of such changes, as recently elucidated in mammalian cells, are discussed.
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Affiliation(s)
- Stephan Clemens
- Department of Plant Physiology and Faculty of Life Science: Food, Nutrition and Health, University of Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
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23
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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: 50] [Impact Index Per Article: 25.0] [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.
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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.
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24
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ZnT1 is a neuronal Zn 2+/Ca 2+ exchanger. Cell Calcium 2021; 101:102505. [PMID: 34871934 DOI: 10.1016/j.ceca.2021.102505] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 10/31/2021] [Accepted: 11/22/2021] [Indexed: 01/22/2023]
Abstract
Zinc transporter 1 (ZnT1; SLC30A1) is present in the neuronal plasma membrane, critically modulating NMDA receptor function and Zn2+ neurotoxicity. The mechanism mediating Zn2+ transport by ZnT1, however, has remained elusive. Here, we investigated ZnT1-dependent Zn2+ transport by measuring intracellular changes of this ion using the fluorescent indicator FluoZin-3. In primary mouse cortical neurons, which express ZnT1, transient addition of extracellular Zn2+ triggered a rise in cytosolic Zn2+, followed by its removal. Knockdown of ZnT1 by adeno associated viral (AAV)-short hairpin RNA (shZnT1) markedly increased rates of Zn2+ rise, and decreased rates of its removal, suggesting that ZnT1 is a primary route for Zn2+ efflux in neurons. Although Zn2+ transport by other members of the SLC30A family is dependent on pH gradients across cellular membranes, altered H+ gradients were not coupled to ZnT1-dependent transport. Removal of cytoplasmic Zn2+, against a large inward gradient during the initial loading phase, suggests that Zn2+ efflux requires a large driving force. We therefore asked if Ca2+ gradients across the membrane can facilitate Zn2+ efflux. Elimination of extracellular Ca2+ abolished Zn2+ efflux, while increased extracellular Ca2+ levels enhanced Zn2+ efflux. Intracellular Ca2+ rises, measured in GCaMP6 expressing neurons, closely paralleled cytoplasmic Zn2+ removal. Taken together, these results strongly suggest that ZnT1 functions as a Zn2+/Ca2+ exchanger, thereby regulating the transport of two ions of fundamental importance in neuronal signaling.
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25
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Foster AW, Young TR, Chivers PT, Robinson NJ. Protein metalation in biology. Curr Opin Chem Biol 2021; 66:102095. [PMID: 34763208 PMCID: PMC8867077 DOI: 10.1016/j.cbpa.2021.102095] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/08/2021] [Accepted: 10/04/2021] [Indexed: 12/11/2022]
Abstract
Inorganic metals supplement the chemical repertoire of organic molecules, especially proteins. This requires the correct metals to associate with proteins at metalation. Protein mismetalation typically occurs when excesses of unbound metals compete for a binding site ex vivo. However, in biology, excesses of metal-binding sites typically compete for limiting amounts of exchangeable metals. Here, we summarise mechanisms of metal homeostasis that sustain optimal metal availabilities in biology. We describe recent progress to understand metalation by comparing the strength of metal binding to a protein versus the strength of binding to competing sites inside cells.
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Affiliation(s)
- Andrew W Foster
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Tessa R Young
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Peter T Chivers
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Nigel J Robinson
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK; Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
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26
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Wu T, Pang Y, Ai HW. Circularly Permuted Far-Red Fluorescent Proteins. BIOSENSORS 2021; 11:438. [PMID: 34821654 PMCID: PMC8615523 DOI: 10.3390/bios11110438] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/01/2021] [Accepted: 11/02/2021] [Indexed: 12/22/2022]
Abstract
The color palette of genetically encoded fluorescent protein indicators (GEFPIs) has expanded rapidly in recent years. GEFPIs with excitation and emission within the "optical window" above 600 nm are expected to be superior in many aspects, such as enhanced tissue penetration, reduced autofluorescence and scattering, and lower phototoxicity. Circular permutation of fluorescent proteins (FPs) is often the first step in the process of developing single-FP-based GEFPIs. This study explored the tolerance of two far-red FPs, mMaroon1 and mCarmine, towards circular permutation. Several initial constructs were built according to previously reported circularly permuted topologies for other FP analogs. Mutagenesis was then performed on these constructs and screened for fluorescent variants. As a result, five circularly permuted far-red FPs (cpFrFPs) with excitation and emission maxima longer than 600 nm were identified. Some displayed appreciable brightness and efficient chromophore maturation. These cpFrFPs variants could be intriguing starting points to further engineer far-red GEFPIs for in vivo tissue imaging.
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Affiliation(s)
- Tianchen Wu
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; (T.W.); (Y.P.)
| | - Yu Pang
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; (T.W.); (Y.P.)
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
| | - Hui-wang Ai
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; (T.W.); (Y.P.)
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
- The UVA Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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Tan CH, Kornfeld K. Zinc is an intracellular signal during sperm activation in Caenorhabditis elegans. Development 2021; 148:273336. [PMID: 34739028 DOI: 10.1242/dev.199836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 09/28/2021] [Indexed: 11/20/2022]
Abstract
Sperm activation is a rapid and dramatic cell differentiation event that does not involve changes in transcription, and the signaling cascades that mediate this process have not been fully defined. zipt-7.1 encodes a zinc transporter, and zipt-7.1(lf) mutants display sperm-activation defects, leading to the hypothesis that zinc signaling mediates sperm activation in Caenorhabditis elegans. Here, we describe the development of a method for dynamic imaging of labile zinc during sperm activation using the zinc-specific fluorescence probe FluoZin-3 AM and time-lapse confocal imaging. Two phases of dynamic changes in labile zinc levels were observed during sperm activation. Forced zinc entry using the zinc ionophore pyrithione activated sperm in vitro, and it suppressed the defects of zipt-7.1(lf) mutants, indicating that high levels of cytosolic zinc are sufficient for sperm activation. We compared activation by zinc pyrithione to activation by extracellular zinc, the Na+/H+ antiporter monensin and the protease cocktail pronase in multiple mutant backgrounds. These results indicate that the protease pathway does not require zinc signaling, suggesting that zinc signaling is sufficient to activate sperm but is not always necessary.
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Affiliation(s)
- Chieh-Hsiang Tan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kerry Kornfeld
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
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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.
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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
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The Multifaceted Roles of Zinc in Neuronal Mitochondrial Dysfunction. Biomedicines 2021; 9:biomedicines9050489. [PMID: 33946782 PMCID: PMC8145363 DOI: 10.3390/biomedicines9050489] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/05/2021] [Accepted: 03/07/2021] [Indexed: 12/17/2022] Open
Abstract
Zinc is a highly abundant cation in the brain, essential for cellular functions, including transcription, enzymatic activity, and cell signaling. However, zinc can also trigger injurious cascades in neurons, contributing to the pathology of neurodegenerative diseases. Mitochondria, critical for meeting the high energy demands of the central nervous system (CNS), are a principal target of the deleterious actions of zinc. An increasing body of work suggests that intracellular zinc can, under certain circumstances, contribute to neuronal damage by inhibiting mitochondrial energy processes, including dissipation of the mitochondrial membrane potential (MMP), leading to ATP depletion. Additional consequences of zinc-mediated mitochondrial damage include reactive oxygen species (ROS) generation, mitochondrial permeability transition, and excitotoxic calcium deregulation. Zinc can also induce mitochondrial fission, resulting in mitochondrial fragmentation, as well as inhibition of mitochondrial motility. Here, we review the known mechanisms responsible for the deleterious actions of zinc on the organelle, within the context of neuronal injury associated with neurodegenerative processes. Elucidating the critical contributions of zinc-induced mitochondrial defects to neurotoxicity and neurodegeneration may provide insight into novel therapeutic targets in the clinical setting.
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Baek K, Ji K, Peng W, Liyanaarachchi SM, Dodani SC. The design and evolution of fluorescent protein-based sensors for monoatomic ions in biology. Protein Eng Des Sel 2021; 34:gzab023. [PMID: 34581820 PMCID: PMC8477612 DOI: 10.1093/protein/gzab023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 08/18/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022] Open
Abstract
Living cells rely on a finely tuned symphony of inorganic ion gradients composed of both cations and anions. This delicate balance is maintained by biological receptors all acting in concert to selectively recognize and position ions for homeostasis. These dynamic processes can be intercepted and visualized with optical microscopy at the organismal, tissue, cellular and subcellular levels using fluorescent protein-based biosensors. Since the first report of such tool for calcium (Ca2+) in 1997, outstanding biological questions and innovations in protein engineering along with associated fields have driven the development of new biosensors for Ca2+ and beyond. In this Review, we summarize a workflow that can be used to generate fluorescent protein-based biosensors to study monoatomic ions in biology. To showcase the scope of this approach, we highlight recent advances reported for Ca2+ biosensors and in detail discuss representative case studies of biosensors reported in the last four years for potassium (K+), magnesium (Mg2+), copper (Cu2+/+), lanthanide (Ln3+) and chloride (Cl-) ions.
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Affiliation(s)
- Kiheon Baek
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
| | - Ke Ji
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
| | - Weicheng Peng
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
| | - Sureshee M Liyanaarachchi
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
| | - Sheel C Dodani
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
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