1
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Ocampo D, Damon LJ, Sanford L, Holtzen SE, Jones T, Allen MA, Dowell RD, Palmer AE. Cellular zinc status alters chromatin accessibility and binding of p53 to DNA. Life Sci Alliance 2024; 7:e202402638. [PMID: 38969365 PMCID: PMC11231577 DOI: 10.26508/lsa.202402638] [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: 02/01/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 07/07/2024] Open
Abstract
Zn2+ is an essential metal required by approximately 850 human transcription factors. How these proteins acquire their essential Zn2+ cofactor and whether they are sensitive to changes in the labile Zn2+ pool in cells remain open questions. Using ATAC-seq to profile regions of accessible chromatin coupled with transcription factor enrichment analysis, we examined how increases and decreases in the labile zinc pool affect chromatin accessibility and transcription factor enrichment. We found 685 transcription factor motifs were differentially enriched, corresponding to 507 unique transcription factors. The pattern of perturbation and the types of transcription factors were notably different at promoters versus intergenic regions, with zinc-finger transcription factors strongly enriched in intergenic regions in elevated Zn2+ To test whether ATAC-seq and transcription factor enrichment analysis predictions correlate with changes in transcription factor binding, we used ChIP-qPCR to profile six p53 binding sites. We found that for five of the six targets, p53 binding correlates with the local accessibility determined by ATAC-seq. These results demonstrate that changes in labile zinc alter chromatin accessibility and transcription factor binding to DNA.
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Affiliation(s)
- Daniel Ocampo
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Leah J Damon
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Lynn Sanford
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Samuel E Holtzen
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Taylor Jones
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Mary A Allen
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, CO, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Robin D Dowell
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, CO, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Amy E Palmer
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA
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2
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Kahali S, Das SK, Kumar R, Gupta K, Kundu R, Bhattacharya B, Nath A, Venkatramani R, Datta A. A water-soluble, cell-permeable Mn(ii) sensor enables visualization of manganese dynamics in live mammalian cells. Chem Sci 2024; 15:10753-10769. [PMID: 39027293 PMCID: PMC11253179 DOI: 10.1039/d4sc00907j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 06/12/2024] [Indexed: 07/20/2024] Open
Abstract
Central roles of Mn2+ ions in immunity, brain function, and photosynthesis necessitate probes for tracking this essential metal ion in living systems. However, developing a cell-permeable, fluorescent sensor for selective imaging of Mn2+ ions in the aqueous cellular milieu has remained a challenge. This is because Mn2+ is a weak binder to ligand-scaffolds and Mn2+ ions quench fluorescent dyes leading to turn-off sensors that are not applicable for in vivo imaging. Sensors with a unique combination of Mn2+ selectivity, μM sensitivity, and response in aqueous media are necessary for not only visualizing labile cellular Mn2+ ions live, but also for measuring Mn2+ concentrations in living cells. No sensor has achieved this combination thus far. Here we report a novel, completely water-soluble, reversible, fluorescent turn-on, Mn2+ selective sensor, M4, with a K d of 1.4 μM for Mn2+ ions. M4 entered cells within 15 min of direct incubation and was applied to image Mn2+ ions in living mammalian cells in both confocal fluorescence intensity and lifetime-based set-ups. The probe was able to visualize Mn2+ dynamics in live cells revealing differential Mn2+ localization and uptake dynamics under pathophysiological versus physiological conditions. In a key experiment, we generated an in-cell Mn2+ response curve for the sensor which allowed the measurement of the endogenous labile Mn2+ concentration in HeLa cells as 1.14 ± 0.15 μM. Thus, our computationally designed, selective, sensitive, and cell-permeable sensor with a 620 nM limit of detection for Mn2+ in water provides the first estimate of endogenous labile Mn2+ levels in mammalian cells.
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Affiliation(s)
- Smitaroopa Kahali
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
| | - Sujit Kumar Das
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
| | - Ravinder Kumar
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
| | - Kunika Gupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
| | - Rajasree Kundu
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
| | - Baivabi Bhattacharya
- Department of Developmental Biology and Genetics, Indian Institute of Science Bangalore 560012 India
| | - Arnab Nath
- Department of Developmental Biology and Genetics, Indian Institute of Science Bangalore 560012 India
| | - Ravindra Venkatramani
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
| | - Ankona Datta
- Department of Chemical Sciences, Tata Institute of Fundamental Research 1 Homi Bhabha Road Mumbai 400005 India
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3
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Holtzen SE, Navid E, Kainov JD, Palmer AE. Transient Zn 2+ deficiency induces replication stress and compromises daughter cell proliferation. Proc Natl Acad Sci U S A 2024; 121:e2321216121. [PMID: 38687796 PMCID: PMC11087780 DOI: 10.1073/pnas.2321216121] [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: 12/09/2023] [Accepted: 03/13/2024] [Indexed: 05/02/2024] Open
Abstract
Cells must replicate their genome quickly and accurately, and they require metabolites and cofactors to do so. Ionic zinc (Zn2+) is an essential micronutrient that is required for hundreds of cellular processes, including DNA synthesis and adequate proliferation. Deficiency in this micronutrient impairs DNA synthesis and inhibits proliferation, but the mechanism is unknown. Using fluorescent reporters to track single cells via long-term live-cell imaging, we find that Zn2+ is required at the G1/S transition and during S phase for timely completion of S phase. A short pulse of Zn2+ deficiency impairs DNA synthesis and increases markers of replication stress. These markers of replication stress are reversed upon resupply of Zn2+. Finally, we find that if Zn2+ is chelated during the mother cell's S phase, daughter cells enter a transient quiescent state, maintained by sustained expression of p21, which disappears upon reentry into the cell cycle. In summary, short pulses of mild Zn2+ deficiency in S phase specifically induce replication stress, which causes downstream proliferation impairments in daughter cells.
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Affiliation(s)
- Samuel E. Holtzen
- Department of Molecular Cellular and Developmental Biology, University of Colorado, Boulder, CO80309
| | - Elnaz Navid
- Department of Biochemistry, University of Colorado, Boulder, CO80309
| | - Joseph D. Kainov
- Department of Biochemistry, University of Colorado, Boulder, CO80309
| | - Amy E. Palmer
- Department of Biochemistry, University of Colorado, Boulder, CO80309
- BioFrontiers Institute, University of Colorado, Boulder, CO80309
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4
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Holtzen SE, Navid E, Kainov JD, Palmer AE. Transient Zn 2+ deficiency induces replication stress and compromises daughter cell proliferation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570860. [PMID: 38106081 PMCID: PMC10723434 DOI: 10.1101/2023.12.08.570860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Cells must replicate their genome quickly and accurately, and they require metabolites and cofactors to do so. Ionic zinc (Zn2+) is an essential micronutrient that is required for hundreds of cellular processes, including DNA synthesis and adequate proliferation. Deficiency in this micronutrient impairs DNA synthesis and inhibits proliferation, but the mechanism is unknown. Using fluorescent reporters to track single cells via long-term live-cell imaging, we find that Zn2+ is required at the G1/S transition and during S-phase for timely completion of S-phase. A short pulse of Zn2+ deficiency impairs DNA synthesis and increases markers of replication stress. These markers of replication stress are reversed upon resupply of Zn2+. Finally, we find that if Zn2+ is removed during the mother cell's S-phase, daughter cells enter a transient quiescent state, maintained by sustained expression of p21, which disappears upon reentry into the cell cycle. In summary, short pulses of mild Zn2+ deficiency in S-phase specifically induce replication stress, which causes downstream proliferation impairments in daughter cells.
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Affiliation(s)
- Samuel E. Holtzen
- Department of Molecular Cellular and Developmental Biology and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80309
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309
| | - Elnaz Navid
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309
| | - Joseph D. Kainov
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309
| | - Amy E. Palmer
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309
- Department of Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO, 80309
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5
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Damon LJ, Ocampo D, Sanford L, Jones T, Allen MA, Dowell RD, Palmer AE. Cellular zinc status alters chromatin accessibility and binding of transcription factor p53 to genomic sites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567954. [PMID: 38045276 PMCID: PMC10690171 DOI: 10.1101/2023.11.20.567954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Zinc (Zn2+) is an essential metal required by approximately 2500 proteins. Nearly half of these proteins act on DNA, including > 850 human transcription factors, polymerases, DNA damage response factors, and proteins involved in chromatin architecture. How these proteins acquire their essential Zn2+ cofactor and whether they are sensitive to changes in the labile Zn2+ pool in cells remain open questions. Here, we examine how changes in the labile Zn2+ pool affect chromatin accessibility and transcription factor binding to DNA. We observed both increases and decreases in accessibility in different chromatin regions via ATAC-seq upon treating MCF10A cells with elevated Zn2+ or the Zn2+-specific chelator tris(2-pyridylmethyl)amine (TPA). Transcription factor enrichment analysis was used to correlate changes in chromatin accessibility with transcription factor motifs, revealing 477 transcription factor motifs that were differentially enriched upon Zn2+ perturbation. 186 of these transcription factor motifs were enriched in Zn2+ and depleted in TPA, and the majority correspond to Zn2+ finger transcription factors. We selected TP53 as a candidate to examine how changes in motif enrichment correlate with changes in transcription factor occupancy by ChIP-qPCR. Using publicly available ChIP-seq and nascent transcription datasets, we narrowed the 50,000+ ATAC-seq peaks to 2164 TP53 targets and subsequently selected 6 high-probability TP53 binding sites for testing. ChIP-qPCR revealed that for 5 of the 6 targets, TP53 binding correlates with the local accessibility determined by ATAC-seq. These results demonstrate that changes in labile zinc directly alter chromatin accessibility and transcription factor binding to DNA.
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Affiliation(s)
- Leah J. Damon
- Department of Biochemistry, University of Colorado, Boulder, CO 80303
| | - Daniel Ocampo
- Department of Biochemistry, University of Colorado, Boulder, CO 80303
| | - Lynn Sanford
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, 80309
| | - Taylor Jones
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, 80309
| | - Mary A. Allen
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, 80309
- BioFrontiers Institute, University of Colorado, Boulder, CO 80303
| | - Robin D. Dowell
- Department of Molecular, Cellular, Developmental Biology, University of Colorado, Boulder, 80309
- BioFrontiers Institute, University of Colorado, Boulder, CO 80303
| | - Amy E. Palmer
- Department of Biochemistry, University of Colorado, Boulder, CO 80303
- BioFrontiers Institute, University of Colorado, Boulder, CO 80303
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6
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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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7
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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.
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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.
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8
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Alshawaf AJ, Alnassar SA, Al-Mohanna FA. The interplay of intracellular calcium and zinc ions in response to electric field stimulation in primary rat cortical neurons in vitro. Front Cell Neurosci 2023; 17:1118335. [PMID: 37180947 PMCID: PMC10174245 DOI: 10.3389/fncel.2023.1118335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 04/10/2023] [Indexed: 05/16/2023] Open
Abstract
Recent pharmacological studies demonstrate a role for zinc (Zn2+) in shaping intracellular calcium (Ca2+) dynamics and vice versa in excitable cells including neurons and cardiomyocytes. Herein, we sought to examine the dynamic of intracellular release of Ca2+ and Zn2+ upon modifying excitability of primary rat cortical neurons using electric field stimulation (EFS) in vitro. We show that exposure to EFS with an intensity of 7.69 V/cm induces transient membrane hyperpolarization together with transient elevations in the cytosolic levels of Ca2+ and Zn2+ ions. The EFS-induced hyperpolarization was inhibited by prior treatment of cells with the K+ channel opener diazoxide. Chemical hyperpolarization had no apparent effect on either Ca2+ or Zn2+. The source of EFS-induced rise in Ca2+ and Zn2+ seemed to be intracellular, and that the dynamic inferred of an interplay between Ca2+ and Zn2+ ions, whereby the removal of extracellular Ca2+ augmented the release of intracellular Ca2+ and Zn2+ and caused a stronger and more sustained hyperpolarization. We demonstrate that Zn2+ is released from intracellular vesicles located in the soma, with major co-localizations in the lysosomes and endoplasmic reticulum. These studies further support the use of EFS as a tool to interrogate the kinetics of intracellular ions in response to changing membrane potential in vitro.
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Affiliation(s)
- Abdullah J. Alshawaf
- Department of Physiological Sciences, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
- Department of Cell Biology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Sarah A. Alnassar
- Department of Cell Biology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Futwan A. Al-Mohanna
- Department of Cell Biology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
- *Correspondence: Futwan A. Al-Mohanna,
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9
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Krall R, Gale JR, Ross MM, Tzounopoulos T, Aizenman E. Intracellular zinc signaling influences NMDA receptor function by enhancing the interaction of ZnT1 with GluN2A. Neurosci Lett 2022; 790:136896. [PMID: 36202195 PMCID: PMC10153101 DOI: 10.1016/j.neulet.2022.136896] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 11/22/2022]
Abstract
Zinc, loaded into glutamate-containing presynaptic vesicles and released into the synapse in an activity-dependent manner, modulates neurotransmission through its actions on postsynaptic targets, prominently via high-affinity inhibition of GluN2A-containing NMDA receptors. Recently, we identified a postsynaptic transport mechanism that regulates endogenous zinc inhibition of NMDARs. In this new model of zinc regulation, the postsynaptic transporter ZnT1 mediates zinc inhibition of NMDARs by binding to GluN2A. Through this interaction, ZnT1, a transporter that moves zinc from the cytoplasm to the extracellular domain, generates a zinc microdomain that modulates NMDAR-mediated neurotransmission. As ZnT1 expression is transcriptionally driven by the metal-responsive transcription factor 1 (MTF-1), we found that intracellular zinc strongly drives MTF-1 in cortical neurons in vitro and increases the number of GluN2A-ZnT1 interactions, thereby enhancing tonic zinc inhibition of NMDAR-mediated currents. Importantly, this effect is absent when the interaction between GluN2A and ZnT1 is disrupted by a cell-permeable peptide. These results suggest that zinc-regulated gene expression can dynamically regulate NMDAR-mediated synaptic processes.
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Affiliation(s)
- Rebecca Krall
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Pittsburgh Hearing Research Center, University of Pittsburgh, PA, USA
| | - Jenna R Gale
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA
| | - Madeline M Ross
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA
| | - Thanos Tzounopoulos
- Pittsburgh Hearing Research Center, University of Pittsburgh, PA, USA; Department of Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Hearing Research Center, University of Pittsburgh, PA, USA.
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10
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Damon LJ, Aaron J, Palmer AE. Single molecule microscopy to profile the effect of zinc status on transcription factor dynamics. Sci Rep 2022; 12:17789. [PMID: 36273101 PMCID: PMC9588069 DOI: 10.1038/s41598-022-22634-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 10/18/2022] [Indexed: 01/19/2023] Open
Abstract
The regulation of transcription is a complex process that involves binding of transcription factors (TFs) to specific sequences, recruitment of cofactors and chromatin remodelers, assembly of the pre-initiation complex and recruitment of RNA polymerase II. Increasing evidence suggests that TFs are highly dynamic and interact only transiently with DNA. Single molecule microscopy techniques are powerful approaches for tracking individual TF molecules as they diffuse in the nucleus and interact with DNA. Here we employ multifocus microscopy and highly inclined laminated optical sheet microscopy to track TF dynamics in response to perturbations in labile zinc inside cells. We sought to define whether zinc-dependent TFs sense changes in the labile zinc pool by determining whether their dynamics and DNA binding can be modulated by zinc. We used fluorescently tagged versions of the glucocorticoid receptor (GR), with two C4 zinc finger domains, and CCCTC-binding factor (CTCF), with eleven C2H2 zinc finger domains. We found that GR was largely insensitive to perturbations of zinc, whereas CTCF was significantly affected by zinc depletion and its dwell time was affected by zinc elevation. These results indicate that at least some transcription factors are sensitive to zinc dynamics, revealing a potential new layer of transcriptional regulation.
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Affiliation(s)
- Leah J. Damon
- grid.266190.a0000000096214564Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303 USA
| | - Jesse Aaron
- grid.443970.dAdvanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147 USA
| | - Amy E. Palmer
- grid.266190.a0000000096214564Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303 USA
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11
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Zhang SY, Liang JJ, Liu YQ. Excessive Zinc Ion Caused PC12 Cell Death Correlating with Inhibition of NOS and Increase of RAGE in Cells. Cell Biochem Biophys 2022; 80:755-761. [PMID: 36068383 DOI: 10.1007/s12013-022-01093-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 08/24/2022] [Indexed: 11/03/2022]
Abstract
Zinc ion (Zn2+) is an important functional factor; however, excessive Zn2+ can be toxic. To understand the neurotoxicity of excessive Zn2+ and the underlying mechanism, PC12 cells were treated with excessive Zn2+ and Zn2+ plus N, N, N', N'-Tetrakisethylenediamine (TPEN), a zinc ion chelator agent. Trypan blue and 3-(4,5-dimethyl-2- thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, thiazolyl blue tetrazolium bromide (MTT) assays were used to test cell viability; the relative kits were used to detect the activity of NOS synthase and the content of the receptor for advanced glycation end product (RAGE) in cells. We observed that excessive zinc caused PC12 cell damage and that TPEN partially reversed cell damage caused by excessive zinc. In addition, excessive zinc decreased total nitric oxide synthase (TNOS) activity in cells, in which constitutive nitric oxide synthase (cNOS) activity was significantly reduced; however, inducible nitric oxide synthase (iNOS) activity was extremely promoted. Moreover, excessive zinc upregulated the expression of RAGE, and TPEN effectively reversed the increase in RAGE induced by excessive zinc ions. Therefore, we concluded that excessive zinc caused PC12 cell damage, correlating with the inhibition of NOS and increase of RAGE induced in cells.
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Affiliation(s)
- Sai-Ya Zhang
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Jing-Jing Liang
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Yan-Qiang Liu
- College of Life Sciences, Nankai University, Tianjin, 300071, China.
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12
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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: 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.
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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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13
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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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14
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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.
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15
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Extended sawhorse waveform for stable zinc detection with fast-scan cyclic voltammetry. Anal Bioanal Chem 2021; 413:6727-6735. [PMID: 34268588 DOI: 10.1007/s00216-021-03529-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 10/20/2022]
Abstract
Zinc (Zn(II)) is a divalent cation involved in regulating intracellular signal transduction and gene expression through transcription factor activity, and can act as a metal neurotransmitter by modulating synaptic activity and neuronal plasticity. Previous research has demonstrated spatial heterogeneity of Zn(II) in the brain, has estimated extracellular concentrations of Zn(II) across various brain regions, and has measured rapid intracellular changes in Zn(II) concentration during glutamate flux. Despite this work, quantification of rapid extracellular Zn(II) release from neurons, on a millisecond time scale, in real time has remained difficult with existing technologies. Here, we have developed an electrochemical waveform, called the "extended sawhorse waveform (ESW)," for fast-scan cyclic voltammetry detection at carbon-fiber microelectrodes which enabled rapid and stable Zn(II) monitoring over time. This waveform was developed to overcome existing challenges in monitoring metallotransmitters stably over time electrochemically by introducing a brief cleaning step to facilitate rapid cleaning of the electrode surface in between scans. The ESW scans from 0.5 V down to -1.0 V, up to 1.45 V for 3 ms (cleaning step), and back to 0.5 V at a scan rate of 400 V/s. Repeated introductions of Zn(II) at the electrode using a traditional waveform cause plating which ultimately deteriorates the sensitivity over time; however, using the ESW, significant improvements in stability were observed. Overall, we provide a unique approach to monitor and quantitate rapid Zn(II) signaling in the brain at carbon electrodes which will impact our ability to advance fundamental knowledge of Zn(II) involvement in extracellular signaling pathways in the brain.
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16
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Krall RF, Tzounopoulos T, Aizenman E. The Function and Regulation of Zinc in the Brain. Neuroscience 2021; 457:235-258. [PMID: 33460731 DOI: 10.1016/j.neuroscience.2021.01.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 12/31/2022]
Abstract
Nearly sixty years ago Fredrich Timm developed a histochemical technique that revealed a rich reserve of free zinc in distinct regions of the brain. Subsequent electron microscopy studies in Timm- stained brain tissue found that this "labile" pool of cellular zinc was highly concentrated at synaptic boutons, hinting a possible role for the metal in synaptic transmission. Although evidence for activity-dependent synaptic release of zinc would not be reported for another twenty years, these initial findings spurred decades of research into zinc's role in neuronal function and revealed a diverse array of signaling cascades triggered or regulated by the metal. Here, we delve into our current understanding of the many roles zinc plays in the brain, from influencing neurotransmission and sensory processing, to activating both pro-survival and pro-death neuronal signaling pathways. Moreover, we detail the many mechanisms that tightly regulate cellular zinc levels, including metal binding proteins and a large array of zinc transporters.
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Affiliation(s)
- Rebecca F Krall
- Department of Neurobiology, University of Pittsburgh School of Medicine, USA; Department of Otolaryngology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, USA
| | - Thanos Tzounopoulos
- Department of Otolaryngology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA.
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, USA.
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17
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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.
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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.
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