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Wu S, Liu C, Tang J, Wu C, Zhang Q, Liu Z, Han J, Xue J, Lin J, Chen Y, Yang J, Zhuo Y, Li Y. Tafluprost promotes axon regeneration after optic nerve crush via Zn 2+-mTOR pathway. Neuropharmacology 2024; 242:109746. [PMID: 37832634 DOI: 10.1016/j.neuropharm.2023.109746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/23/2023] [Accepted: 10/04/2023] [Indexed: 10/15/2023]
Abstract
PURPOSE To investigate whether Tafluprost could promote optic nerve regeneration in mice after optic nerve crush (ONC) and determine the underlying molecular mechanism. METHODS Tafluprost was injected into the vitreous body immediately after ONC. The level of Zn2+ in the inner plexiform layer (IPL) of the retina was stained using autometallography (AMG). The number of survival retinal ganglion cells (RGCs) was determined via dual staining with RGC markers Tuj1 and RBPMS. Individual axons that regenerated to 0.25, 0.5, 0.75 and 1 mm were manually counted in the whole-mount optic nerve labeled by cholera toxin B fragment (CTB). Immunofluorescence and Western blot were performed to detect protein expression levels. Pattern electroretinogram was used to evaluate RGCs function. RESULTS Tafluprost promoted RGC survival in a dose-dependent manner with an optimal concentration of 1 μM. Tafluprost significantly decreased ZnT-3 expression and Zn2+ accumulation in the IPL of retina. Tafluprost stimulated intense axonal regeneration and maintained RGCs function compared to control. Mechanistically, Tafluprost and Zn2+ elimination treatment (TPEN or ZnT-3 deletion) can activate the mTOR pathway with an improved percentage of pS6+ RGCs in the retina. However, rapamycin, a specific inhibitor of the mTOR1, inhibited the activation of the mTOR pathway and abolished the regenerative effect mediated by Tafluprost. Tafluprost also inhibited the upregulation of p62, LC3 and Beclin-1, attenuated the overactivation of microglia/macrophages and downregulated the expression of TNFα and IL-1β. CONCLUSIONS Our results suggest that Tafluprost promoted axon regeneration via regulation of the Zn2+-mTOR pathway, and provide novel research directions for glaucomatous optic nerve injury mechanisms.
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Affiliation(s)
- Siting Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Canying Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Jiahui Tang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Caiqing Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Qi Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Zhe Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Jiaxu Han
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Jingfei Xue
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Jicheng Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Yuze Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Jinpeng Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China
| | - Yehong Zhuo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China.
| | - Yiqing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, 510060, China.
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Zinc ionophores isolated from Terminalia bellirica fruit rind extract protect against cardiomyocyte hypoxia/reoxygenation injury. Bioorg Med Chem 2021; 46:116394. [PMID: 34509160 DOI: 10.1016/j.bmc.2021.116394] [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: 07/16/2021] [Revised: 08/27/2021] [Accepted: 09/01/2021] [Indexed: 11/21/2022]
Abstract
The study aimed to isolate and characterize zinc ionophores from Terminalia bellirica fruit using a liposome assay and test its utility in H9c2 rat cardiomyoblasts cells subjected to hypoxia/reoxygenation. Ethyl acetate extract that exhibited zinc ionophore activity was resolved to yield three polyphenols that were characterized as epicatechin-3-gallate (ECG), epigallocatechin-3-gallate (EGCG) and epigallocatechin (EGC) by nuclear magnetic resonance and electrospray ionization-mass spectra. The polyphenols enhanced the uptake of zinc into the liposomes and increased FluoZin-3 fluorescence. These polyphenols in the presence of 10 μM ZnCl2 enhanced the zinc import into H9c2 cells, whose intracellular zinc levels were otherwise lowered upon hypoxia/reoxygenation. EGCG proved to be more potent than ECG, which indeed was more effective than EGC in improving cellular zinc levels and in attenuating the apoptosis of H9c2 cells after hypoxia/reoxygenation injury. The polyphenols required zinc for anti-apoptotic effect. The cardioprotective effect is indeed due to enhanced zinc uptake mediated by these polyphenols.
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Lo MN, Damon LJ, Wei Tay J, Jia S, Palmer AE. Single cell analysis reveals multiple requirements for zinc in the mammalian cell cycle. eLife 2020; 9:e51107. [PMID: 32014109 PMCID: PMC7000218 DOI: 10.7554/elife.51107] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/30/2019] [Indexed: 01/01/2023] Open
Abstract
Zinc is widely recognized as essential for growth and proliferation, yet the mechanisms of how zinc deficiency arrests these processes remain enigmatic. Here we induce subtle zinc perturbations and track asynchronously cycling cells throughout division using fluorescent reporters, high throughput microscopy, and quantitative analysis. Zinc deficiency induces quiescence and resupply stimulates synchronized cell-cycle reentry. Monitoring cells before and after zinc deprivation we found the position of cells within the cell cycle determined whether they either went quiescent or entered another cell cycle but stalled in S-phase. Stalled cells exhibited prolonged S-phase, were defective in DNA synthesis and had increased DNA damage levels, suggesting a role for zinc in maintaining genome integrity. Finally, we demonstrate zinc deficiency-induced quiescence occurs independently of DNA-damage response pathways, and is distinct from mitogen removal and spontaneous quiescence. This suggests a novel pathway to quiescence and reveals essential micronutrients play a role in cell cycle regulation.
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Affiliation(s)
- Maria N Lo
- Department of BiochemistryUniversity of Colorado, BoulderBoulderUnited States
- BioFrontiers InstituteUniversity of Colorado, BoulderBoulderUnited States
| | - Leah J Damon
- Department of BiochemistryUniversity of Colorado, BoulderBoulderUnited States
- BioFrontiers InstituteUniversity of Colorado, BoulderBoulderUnited States
| | - Jian Wei Tay
- Department of BiochemistryUniversity of Colorado, BoulderBoulderUnited States
- BioFrontiers InstituteUniversity of Colorado, BoulderBoulderUnited States
| | - Shang Jia
- Department of ChemistryUniversity of California, BerkeleyBerkeleyUnited States
| | - Amy E Palmer
- Department of BiochemistryUniversity of Colorado, BoulderBoulderUnited States
- BioFrontiers InstituteUniversity of Colorado, BoulderBoulderUnited States
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Intracellular zinc activates KCNQ channels by reducing their dependence on phosphatidylinositol 4,5-bisphosphate. Proc Natl Acad Sci U S A 2017; 114:E6410-E6419. [PMID: 28716904 DOI: 10.1073/pnas.1620598114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
M-type (Kv7, KCNQ) potassium channels are proteins that control the excitability of neurons and muscle cells. Many physiological and pathological mechanisms of excitation operate via the suppression of M channel activity or expression. Conversely, pharmacological augmentation of M channel activity is a recognized strategy for the treatment of hyperexcitability disorders such as pain and epilepsy. However, physiological mechanisms resulting in M channel potentiation are rare. Here we report that intracellular free zinc directly and reversibly augments the activity of recombinant and native M channels. This effect is mechanistically distinct from the known redox-dependent KCNQ channel potentiation. Interestingly, the effect of zinc cannot be attributed to a single histidine- or cysteine-containing zinc-binding site within KCNQ channels. Instead, zinc dramatically reduces KCNQ channel dependence on its obligatory physiological activator, phosphatidylinositol 4,5-bisphosphate (PIP2). We hypothesize that zinc facilitates interactions of the lipid-facing interface of a KCNQ protein with the inner leaflet of the plasma membrane in a way similar to that promoted by PIP2 Because zinc is increasingly recognized as a ubiquitous intracellular second messenger, this discovery might represent a hitherto unknown native pathway of M channel modulation and provide a fresh strategy for the design of M channel activators for therapeutic purposes.
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TPEN, a Specific Zn 2+ Chelator, Inhibits Sodium Dithionite and Glucose Deprivation (SDGD)-Induced Neuronal Death by Modulating Apoptosis, Glutamate Signaling, and Voltage-Gated K + and Na + Channels. Cell Mol Neurobiol 2016; 37:235-250. [PMID: 26983717 DOI: 10.1007/s10571-016-0364-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/08/2016] [Indexed: 02/06/2023]
Abstract
Hypoxia-ischemia-induced neuronal death is an important pathophysiological process that accompanies ischemic stroke and represents a major challenge in preventing ischemic stroke. To elucidate factors related to and a potential preventative mechanism of hypoxia-ischemia-induced neuronal death, primary neurons were exposed to sodium dithionite and glucose deprivation (SDGD) to mimic hypoxic-ischemic conditions. The effects of N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), a specific Zn2+-chelating agent, on SDGD-induced neuronal death, glutamate signaling (including the free glutamate concentration and expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor (GluR2) and N-methyl-D-aspartate (NMDA) receptor subunits (NR2B), and voltage-dependent K+ and Na+ channel currents were also investigated. Our results demonstrated that TPEN significantly suppressed increases in cell death, apoptosis, neuronal glutamate release into the culture medium, NR2B protein expression, and I K as well as decreased GluR2 protein expression and Na+ channel activity in primary cultured neurons exposed to SDGD. These results suggest that TPEN could inhibit SDGD-induced neuronal death by modulating apoptosis, glutamate signaling (via ligand-gated channels such as AMPA and NMDA receptors), and voltage-gated K+ and Na+ channels in neurons. Hence, Zn2+ chelation might be a promising approach for counteracting the neuronal loss caused by transient global ischemia. Moreover, TPEN could represent a potential cell-targeted therapy.
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Ziemińska E, Strużyńska L. Zinc Modulates Nanosilver-Induced Toxicity in Primary Neuronal Cultures. Neurotox Res 2015; 29:325-43. [PMID: 26690781 PMCID: PMC4712226 DOI: 10.1007/s12640-015-9583-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 11/23/2015] [Accepted: 11/28/2015] [Indexed: 11/07/2022]
Abstract
Silver nanoparticles (NAg) have recently become one of the most commonly used nanomaterials. Since the ability of nanosilver to enter the brain has been confirmed, there has been a need to investigate mechanisms of its neurotoxicity. We previously showed that primary neuronal cultures treated with nanosilver undergo destabilization of calcium homeostasis via a mechanism involving glutamatergic NMDA receptors. Considering the fact that zinc interacts with these receptors, the aim of the present study was to examine the role of zinc in mechanisms of neuronal cell death in primary cultures. In cells treated with nanosilver, we noted an imbalance between extracellular and intracellular zinc levels. Thus, the influence of zinc deficiency and supplementation on nanosilver-evoked cytotoxicity was investigated by treatment with TPEN (a chelator of zinc ions), or ZnCl2, respectively. Elimination of zinc leads to complete death of nanosilver-treated CGCs. In contrast, supplementation with ZnCl2 increases viability of CGCs in a dose-dependent manner. Addition of zinc provided protection against the extra/intracellular calcium imbalance in a manner similar to MK-801, an antagonist of NMDA receptors. Zinc chelation by TPEN decreases the mitochondrial potential and dramatically increases the rate of production of reactive oxygen species. Our results indicate that zinc supplementation positively influences nanosilver-evoked changes in CGCs. This is presumed to be due to an inhibitory effect on NMDA-sensitive calcium channels.
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Affiliation(s)
- Elżbieta Ziemińska
- Laboratory of Pharmaconeurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego str, 02-106, Warsaw, Poland
| | - Lidia Strużyńska
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego str, 02-106, Warsaw, Poland.
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Seo BR, Lee SJ, Cho KS, Yoon YH, Koh JY. The zinc ionophore clioquinol reverses autophagy arrest in chloroquine-treated ARPE-19 cells and in APP/mutant presenilin-1-transfected Chinese hamster ovary cells. Neurobiol Aging 2015; 36:3228-3238. [PMID: 26453000 DOI: 10.1016/j.neurobiolaging.2015.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/24/2015] [Accepted: 09/09/2015] [Indexed: 10/23/2022]
Abstract
Arrested autophagy may contribute to the pathogenesis of Alzheimer's disease. Because we found that chloroquine (CQ) causes arrested autophagy but clioquinol (ClioQ), a zinc ionophore, activates autophagic flux, in the present study, we examined whether ClioQ can overcome arrested autophagy induced by CQ or mutant presenilin-1 (mPS1). CQ induced vacuole formation and cell death in adult retinal pigment epithelial (ARPE-19) cells, but co-treatment with ClioQ attenuated CQ-associated toxicity in a zinc-dependent manner. Increases in lysosome dilation and blockage of autophagic flux by CQ were also markedly attenuated by ClioQ treatment. Interestingly, CQ increased lysosomal pH in amyloid precursor protein (APP)/mPS1-expressing Chinese hamster ovary 7WΔE9 (CHO-7WΔE9) cell line, and ClioQ partially re-acidified lysosomes. Furthermore, accumulation of amyloid-β (Aβ) oligomers in CHO-7WΔE9 cells was markedly attenuated by ClioQ. Moreover, intracellular accumulation of exogenously applied fluorescein isothiocyanate-conjugated Aβ(1-42) was also increased by CQ but was returned to control levels by ClioQ. These results suggest that modulation of lysosomal functions by manipulating lysosomal zinc levels may be a useful strategy for clearing intracellular Aβ oligomers.
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Affiliation(s)
- Bo-Ra Seo
- Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Sook-Jeong Lee
- Department of New Drug Discovery and Development, Chungnam National University, Daejeon, Korea
| | - Kyung Sook Cho
- Department of Endocrinology and Metabolism, Kyung Hee University Hospital at Gangdong, Kyung Hee University, School of Medicine, Seoul, Korea
| | - Young Hee Yoon
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae-Young Koh
- Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea; Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
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Wang WM, Liu Z, Liu AJ, Wang YX, Wang HG, An D, Heng B, Xie LH, Duan JL, Liu YQ. The Zinc Ion Chelating Agent TPEN Attenuates Neuronal Death/apoptosis Caused by Hypoxia/ischemia Via Mediating the Pathophysiological Cascade Including Excitotoxicity, Oxidative Stress, and Inflammation. CNS Neurosci Ther 2015; 21:708-17. [PMID: 26190227 DOI: 10.1111/cns.12428] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Revised: 06/02/2015] [Accepted: 06/03/2015] [Indexed: 12/14/2022] Open
Abstract
AIMS We aim to determine the significant effect of TPEN, a Zn(2+) chelator, in mediating the pathophysiological cascade in neuron death/apoptosis induced by hypoxia/ischemia. METHODS We conducted both in vivo and in vitro experiments in this study. PC12 cells were used to establish hypoxia/ischemia model by applying oxygen-glucose deprivation (OGD). SHR-SP rats were used to establish an acute ischemic model by electrocoagulating middle cerebral artery occlusion. The effect of TPEN on neuron death/apoptosis was evaluated. In addition, the relative biomarks of excitotoxicity, oxidative stress, and inflammation reactions in hypoxia/ischemia PC12 cell model as well as in SHR-SP rat hypoxia/ischemia model were also assessed. RESULTS TPEN significantly attenuates the neurological deficit, reduced the cerebral infarction area and the ratio of apoptotic neurons, and increased the expression of GluR2 in the rat hypoxia/ischemia brain. TPEN also increased blood SOD activity, decreased blood NOS activity and blood MDA and IL-6 contents in rats under hypoxia/ischemia. In addition, TPEN significantly inhibited the death and apoptosis of cells and attenuated the alteration of GluR2 and NR2 expression caused by OGD or OGD plus high Zn(2+) treatments. CONCLUSIONS Zn(2+) is involved in neural cell apoptosis and/or death caused by hypoxia/ischemia via mediating excitotoxicity, oxidative stress, and inflammation.
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Affiliation(s)
- Wei-Ming Wang
- College of Life Sciences, Nankai University, Tianjin, China.,Department of Pharmacology, Second Military Medical University, Shanghai, China
| | - Zhao Liu
- College of Life Sciences, Nankai University, Tianjin, China
| | - Ai-Jun Liu
- Department of Pharmacology, Second Military Medical University, Shanghai, China
| | - Yu-Xiang Wang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Hong-Gang Wang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Di An
- College of Life Sciences, Nankai University, Tianjin, China
| | - Bin Heng
- College of Life Sciences, Nankai University, Tianjin, China
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - Jun-Li Duan
- Department of Gerontology, Xin Hua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan-Qiang Liu
- College of Life Sciences, Nankai University, Tianjin, China
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Abstract
Chloroquine is an established antimalarial agent that has been recently tested in clinical trials for its anticancer activity. The favorable effect of chloroquine appears to be due to its ability to sensitize cancerous cells to chemotherapy, radiation therapy, and induce apoptosis. The present study investigated the interaction of zinc ions with chloroquine in a human ovarian cancer cell line (A2780). Chloroquine enhanced zinc uptake by A2780 cells in a concentration-dependent manner, as assayed using a fluorescent zinc probe. This enhancement was attenuated by TPEN, a high affinity metal-binding compound, indicating the specificity of the zinc uptake. Furthermore, addition of copper or iron ions had no effect on chloroquine-induced zinc uptake. Fluorescent microscopic examination of intracellular zinc distribution demonstrated that free zinc ions are more concentrated in the lysosomes after addition of chloroquine, which is consistent with previous reports showing that chloroquine inhibits lysosome function. The combination of chloroquine with zinc enhanced chloroquine's cytotoxicity and induced apoptosis in A2780 cells. Thus chloroquine is a zinc ionophore, a property that may contribute to chloroquine's anticancer activity.
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Huang Z, Zhang XA, Bosch M, Smith SJ, Lippard SJ. Tris(2-pyridylmethyl)amine (TPA) as a membrane-permeable chelator for interception of biological mobile zinc. Metallomics 2013; 5:648-55. [PMID: 23715510 DOI: 10.1039/c3mt00103b] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We report the characterization of tris(2-pyridylmethyl)amine (TPA) as a membrane-permeable zinc chelator for intercepting biological mobile zinc. Compared to N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), TPA chelates zinc with faster kinetics in cuvettes, live cells, and brain slices. TPA also is generally less toxic than TPEN in cell culture. Mechanistic analysis indicates that these improvements arise from both the electronic and steric properties of TPA including weaker metal-binding affinity, lower pKa, and smaller size. These results demonstrate that TPA chelation is a valuable addition to the methodologies available for investigating mobile zinc in biology.
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Affiliation(s)
- Zhen Huang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Xue J, Wang S, Wu J, Hannafon BN, Ding WQ. Zinc at sub-cytotoxic concentrations induces heme oxygenase-1 expression in human cancer cells. Cell Physiol Biochem 2013; 32:100-10. [PMID: 23868099 DOI: 10.1159/000350128] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2013] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND/AIMS This study investigated the effects of zinc on heme oxygenase-1 (HO-1) expression in human cancer cells. METHODS/RESULTS Zinc at sub-cytotoxic concentrations (50-100 μM) induces HO-1 expression in the MDA-MB-231 (human breast cancer) and A2780 (human ovarian cancer) cell lines in a concentration- and time-dependent manner. The induction of HO-1 by zinc was detected after 4-6 hours of treatment, reached maximal level at 8 hours, and declined thereafter. Using a human HO-1 gene promoter reporter construct, we identified two antioxidant response elements (AREs) that mediated the zinc-induced increase in HO-1 gene transcription, indicating that the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling pathway is involved in this event. This assumption was supported by the observations that knockdown of Nrf2 expression compromised the zinc-induced increase in HO-1 gene transcription, and that zinc increased Nrf2 protein expression and the Nrf2 binding to the AREs. Additionally, we found that the zinc-induced HO-1 gene transcription can be enhanced by clioquinol, a zinc ionophore, and reversed by pretreatment with TPEN, a known zinc chelator, indicating that an increase in intracellular zinc levels is responsible for this induction. CONCLUSION These findings demonstrate that zinc at sub-cytotoxic concentrations induces HO-1 expression in human cancer cells. The biological significance of this induction merits further investigation.
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Affiliation(s)
- Jing Xue
- School of Radiation Medicine and Protection, Soochow University, Suzhou, P. R. China
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San Miguel SM, Opperman LA, Allen EP, Zielinski JE, Svoboda KK. Antioxidant combinations protect oral fibroblasts against metal-induced toxicity. Arch Oral Biol 2013; 58:299-310. [DOI: 10.1016/j.archoralbio.2012.05.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/18/2012] [Accepted: 05/29/2012] [Indexed: 10/28/2022]
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Bai S, Sheline CR, Zhou Y, Sheline CT. A reduced zinc diet or zinc transporter 3 knockout attenuate light induced zinc accumulation and retinal degeneration. Exp Eye Res 2012; 108:59-67. [PMID: 23274584 DOI: 10.1016/j.exer.2012.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 11/20/2012] [Accepted: 12/12/2012] [Indexed: 01/05/2023]
Abstract
Our previous study on retinal light exposure suggests the involvement of zinc (Zn(2+)) toxicity in the death of RPE and photoreceptors (LD) which could be attenuated by pyruvate and nicotinamide, perhaps through restoration of NAD(+) levels. In the present study, we examined Zn(2+) toxicity, and the effects of NAD(+) restoration in primary retinal cultures. We then reduced Zn(2+) levels in rodents by reducing Zn(2+) levels in the diet, or by genetics and measured LD. Sprague Dawley albino rats were fed 2, or 61 mg Zn(2+)/kg of diet for 3 weeks, and exposed to 18 kLux of white light for 4 h. We light exposed (70 kLux of white light for 50 h) Zn(2+) transporter 3 knockout (ZnT3-KO, no synaptic Zn(2+)), or RPE65 knockout mice (RPE65-KO, lack rhodopsin cycling), or C57/BI6/J controls and determined light damage and Zn(2+) staining. Retinal Zn(2+) staining was examined at 1 h and 4 h after light exposure. Retinas were examined after 7 d by optical coherence tomography and histology. After LD, rats fed the reduced Zn(2+) diet showed less photoreceptor Zn(2+) staining and degeneration compared to a normal Zn(2+) diet. Similarly, ZnT3-KO and RPE65-KO mice showed less Zn(2+) staining, NAD(+) loss, and RPE or photoreceptor death than C57/BI6/J control mice. Dietary or ZnT3-dependent Zn(2+) stores, and intracellular Zn(2+) release from rhodopsin recycling are suggested to be involved in light-induced retinal degeneration. These results implicate novel rhodopsin-mediated mechanisms and therapeutic targets for LD. Our companion manuscript demonstrates that pharmacologic, circadian, or genetic manipulations which maintain NAD(+) levels reduce LD.
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Affiliation(s)
- Shi Bai
- Department of Ophthalmology and The Neuroscience Center of Excellence, LSU Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA.
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Caldeira MV, Curcio M, Leal G, Salazar IL, Mele M, Santos ARA, Melo CV, Pereira P, Canzoniero LMT, Duarte CB. Excitotoxic stimulation downregulates the ubiquitin-proteasome system through activation of NMDA receptors in cultured hippocampal neurons. Biochim Biophys Acta Mol Basis Dis 2012; 1832:263-74. [PMID: 23069389 DOI: 10.1016/j.bbadis.2012.10.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 09/20/2012] [Accepted: 10/09/2012] [Indexed: 01/30/2023]
Abstract
Overactivation of glutamate receptors contributes to neuronal damage (excitotoxicity) in ischemic stroke but the detailed mechanisms are not fully elucidated. Brain ischemia is also characterized by an impairment of the activity of the proteasome, one of the major proteolytic systems in neurons. We found that excitotoxic stimulation with glutamate rapidly decreases ATP levels and the proteasome activity, and induces the disassembly of the 26S proteasome in cultured rat hippocampal neurons. Downregulation of the proteasome activity, leading to an accumulation of ubiquitinated proteins, was mediated by calcium entry through NMDA receptors and was only observed in the nuclear fraction. Furthermore, excitotoxicity-induced proteasome inhibition was partially sensitive to cathepsin-L inhibition and was specifically induced by activation of extrasynaptic NMDA receptors. Oxygen and glucose deprivation induced neuronal death and downregulated the activity of the proteasome by a mechanism dependent on the activation of NMDA receptors. Since deubiquitinating enzymes may regulate proteins half-life by counteracting ubiquitination, we also analyzed how their activity is regulated under excitotoxic conditions. Glutamate stimulation decreased the total deubiquitinase activity in hippocampal neurons, but was without effect on the activity of Uch-L1, showing that not all deubiquitinases are affected. These results indicate that excitotoxic stimulation with glutamate has multiple effects on the ubiquitin-proteasome system which may contribute to the demise process in brain ischemia and in other neurological disorders.
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Zheng J, Zhang XX, Yu H, Taggart JE, Ding WQ. Zinc at cytotoxic concentrations affects posttranscriptional events of gene expression in cancer cells. Cell Physiol Biochem 2012; 29:181-8. [PMID: 22415087 DOI: 10.1159/000337599] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2011] [Indexed: 12/23/2022] Open
Abstract
Zinc at cytotoxic concentrations has been shown to regulate gene transcription in cancer cells, though zinc's involvement in posttranscriptional regulation is less characterized. In this study, we investigated the involvement of cytotoxic zinc in the posttranscriptional steps of gene expression. Clioquinol, a well-established zinc ionophore, was used to raise intracellular zinc to reported cytotoxic levels. The MCF-7 human cancer cell line was applied as a cell model system. Several parameters were used as indictors of posttranscriptional regulation, including p-body formation, microRNA profiling, expression level of proteins known to regulate mRNA degradation, microRNA processing, and protein translation. p-body formation was observed in MCF-7 cells using several molecules known as p-body components. Clioquinol plus zinc enhanced p-body assembly in MCF-7 cells. This enhancement was zinc-specific and could be blocked by a high affinity zinc chelator. The enhancement does not seem to be due to a stress response, as paclitaxel, a commonly used chemotherapeutic, did not cause enhanced p-body formation at a highly cytotoxic concentration. microRNA profiling indicated that clioquinol plus zinc globally down-regulates microRNA expression in this model system, which is associated with the reduced expression of Dicer, an enzyme key to microRNA maturation, and Ago2, a protein essential for microRNA stability. This study demonstrates that ionophoric zinc can induce cytotoxicity in cancer cells by globally regulating posttranscriptional events.
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Affiliation(s)
- Jie Zheng
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Rahman MS, Sarker JC, Ghosh S, Kabir SE. The First Carbonyl-Substituted Derivative of [Mn2(CO)6(µ-pyS)2]. Aust J Chem 2012. [DOI: 10.1071/ch12021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Reaction of [Mn2(CO)6(μ-pyS)2] (1) with (Ph3P)2Ni(CO)2 at room temperature affords [Mn2(CO)5(PPh3)(μ-pyS)2] (3) which is the first carbonyl-substituted derivative of 1. A mononuclear complex fac-[Mn(CO)3(PPh3)(κ2-pyS)] (4) is also isolated as a minor product in this reaction. The formation of 3 allows us to propose a different mechanism operating in this reaction. A similar reaction between [Re2(CO)6(μ-pyS)2] (2) and (Ph3P)2Ni(CO)2 gives only mononuclear fac-[Re(CO)3(PPh3)(κ2-pyS)] (5). Both 4 and 5 undergo CO substitution to produce [M(CO)2(PPh3)2(κ2-pyS)] (6, M = Mn; 7, M = Re) when treated with (Ph3P)2Ni(CO)2 in boiling THF. Complex 3 also reacts with further (Ph3P)2Ni(CO)2 at room temperature to give 4 and 6. The molecular structures of 3 and 4 have been established by single crystal X-ray diffraction analyses.
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Carraway RE, Dobner PR. Zinc pyrithione induces ERK- and PKC-dependent necrosis distinct from TPEN-induced apoptosis in prostate cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:544-57. [PMID: 22027089 DOI: 10.1016/j.bbamcr.2011.09.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 09/09/2011] [Accepted: 09/13/2011] [Indexed: 10/16/2022]
Abstract
Zinc dyshomeostasis can induce cell death. However, the mechanisms involved have not been fully elucidated in prostate cancer (PCa) cells, which differ dramatically from normal cells in their zinc handling ability. Here, we studied the effects of the ionophore Zn-pyrithione (ZP) and the chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN). Both compounds induced cell death at micromolar concentrations when incubated with androgen-dependent (LNCaP), androgen-independent (PC3, DU145) and androgen-sensitive (C4-2) PCa cell-lines. Compared to PCa cells, RWPE1 prostate epithelial cells were less sensitive to ZP and more sensitive to TPEN, but total cellular zinc levels were changed similarly. ZnSO4 enhanced the toxicity of ZP, but inhibited the effects of TPEN as expected. The morphological/biochemical responses to ZP and TPEN differed. ZP decreased ATP levels and stimulated ERK, AKT and PKC phosphorylation. DNA laddering was observed only at low doses of ZP but all doses of TPEN. TPEN activated caspase 3/7 and induced PARP-cleavage, DNA-fragmentation, ROS-formation and apoptotic bodies. PKC and ERK-pathway inhibitors, and antioxidants protected against ZP-induced but not TPEN-induced death. Inhibitors of MPTP-opening protected both. Cell death in response to TPEN (but not ZP) was diminished by a calpain inhibitor and largely prevented by a caspase 3 inhibitor. Overall, the results indicated primarily a necrotic cell death for ZP and an apoptotic cell death for TPEN. The enhanced sensitivity of PCa cells to ZP and the apparent ability of ZP and TPEN to kill quiescent and rapidly dividing cells in a p53-independent manner suggest that ZP/TPEN might be used to develop adjunct treatments for PCa.
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Affiliation(s)
- Robert E Carraway
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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18
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Park MH, Lee SJ, Byun HR, Kim Y, Oh YJ, Koh JY, Hwang JJ. Clioquinol induces autophagy in cultured astrocytes and neurons by acting as a zinc ionophore. Neurobiol Dis 2011; 42:242-51. [PMID: 21220021 DOI: 10.1016/j.nbd.2011.01.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 11/04/2010] [Accepted: 01/02/2011] [Indexed: 10/18/2022] Open
Abstract
Recent studies have demonstrated that clioquinol, an antibiotic with an anti-amyloid effect, acts as a zinc ionophore under physiological conditions. Because increases in labile zinc may induce autophagy, we examined whether clioquinol induces autophagy in cultured astrocytes in a zinc-dependent manner. Within 1h of exposure to 0.1-10 μM clioquinol, the levels of microtubule-associated protein 1 light chain 3 (LC3)-II, a marker of autophagy, began to increase in astrocytes. Confocal live-cell imaging of GFP-LC3-transfected astrocytes showed the formation of LC3(+) autophagic vacuoles (AVs), providing a further indication that clioquinol induced autophagy. Addition of 3-methyladenine or small-interfering RNA against autophagy-related gene 6 (ATG6/Beclin-1) blocked clioquinol-induced increases in LC3-II. FluoZin-3 fluorescence microscopy showed that, like the zinc ionophore pyrithione, clioquinol increased intracellular zinc levels in the cytosol and AVs in an extracellular zinc-dependent manner. Zinc chelation with N,N,N',N'-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN) reduced, and addition of zinc increased the levels of LC3-II and LC3(+) puncta, indicating that zinc influx plays a key role therein. Moreover, astrocytes and SH-SY5Y cells expressing mutant huntingtin (mHttQ74) accumulated less aggregates when treated with clioquinol, and this effect was reversed by TPEN. These results indicate that clioquinol-induced autophagy is likely to be physiologically functional. The present study demonstrates that clioquinol induces autophagy in a zinc-dependent manner and contributes to clearance of aggregated proteins in astrocytes and neurons. Hence, in addition to its metal-chelating effect in and around amyloid beta (Aβ) plaques, clioquinol may contribute to the reduction of Aβ loads by activating autophagy by increasing or normalizing intracellular zinc levels in brain cells.
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Affiliation(s)
- Mi-Ha Park
- Department of Biology, University of Yonsei, College of Life Science and Biotechnology, Seoul 120-749, Republic of Korea
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19
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Fetal bovine serum requirement for pyrrolidine dithiocarbamate-induced apoptotic cell death of MCF-7 breast tumor cells. Eur J Pharmacol 2010; 649:135-9. [DOI: 10.1016/j.ejphar.2010.09.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/16/2010] [Indexed: 12/18/2022]
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Abstract
Compounds that bind metals such as copper and zinc have many biological activities, including the ability to induce apoptosis in cancer cells. Although some of these compounds have been considered to act as chelators of metals, decreasing their bioavailability, others increase intracellular metal concentrations. We review recent work regarding the recognition of the biological effects of metal ionophores with different structures, particularly with regard to their actions upon cancer cells focusing on dithiocarbamates, pyrithione, and the 8-hydroxyquinoline derivative, clioquinol. We provide a biologically based classification of metal-binding compounds that allows an experimental distinction between chelators and ionophores that can be readily used by biologists, which may lead to further study and classification of metal-binding drugs. Metal ionophores may kill cancer cells by a number of mechanisms, including lysosomal disruption and proteasome inhibition, and likely others. Because some of these compounds have been safely administered to animals and humans, they have the potential to become clinically useful anticancer agents.
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Affiliation(s)
- Wei-Qun Ding
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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21
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Endogenous zinc mediates apoptotic programmed cell death in the developing brain. Neurotox Res 2009; 17:156-66. [PMID: 19609831 DOI: 10.1007/s12640-009-9085-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 05/29/2009] [Accepted: 06/12/2009] [Indexed: 10/20/2022]
Abstract
Endogenous zinc can mediate the apoptotic programmed cell death (PCD) in the developing brain. Intensive accumulation of labile zinc occurs in almost all neurons undergoing PCD in the developing rat brain. Based on the greater frequency of neurons with intensive zinc accumulation compared to apoptotic neurons, it is inferred that cytosolic zinc accumulation precedes apoptotic PCD. To determine the role of intracellular labile zinc in developmental apoptosis, we subcutaneously injected the membrane-permeant zinc chelator, N,N,N',N-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN) into postnatal rats for 7 days after birth. TPEN chelated intraneuronal zinc without modulating the expression of the zinc-regulating proteins, ZnT-1, ZnT-3, and synaptophysin. The frequency of apoptotic neurons significantly decreased in TPEN-treated rat brains compared with that in normal postnatal rats. Activating cleavages of caspase-9 and -3, and mitochondrial pro-apoptotic Bax expression were reduced, whereas expression of anti-apoptotic Bcl-2 was increased. Thus, intracerebral zinc chelation may arrest PCD in the developing brain by interfering with the caspase-dependent apoptotic pathway. The present study demonstrates that intracellular zinc acts as a key mediator of developmental apoptosis and therefore provides the first in vivo evidence that endogenous labile zinc causes neuronal apoptosis.
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Ding WQ, Yu HJ, Lind SE. Zinc-binding compounds induce cancer cell death via distinct modes of action. Cancer Lett 2008; 271:251-9. [PMID: 18639975 DOI: 10.1016/j.canlet.2008.06.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 06/06/2008] [Accepted: 06/10/2008] [Indexed: 01/18/2023]
Abstract
Metal-binding compounds have been shown to have anticancer activity and are being evaluated clinically as anticancer agents. We have recently found that a zinc-binding compound, 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol), kills cancer cells by transporting zinc into the cells. We therefore compared the action of clioquinol with two other cytotoxic zinc-binding compounds, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and pyrrolidine dithiocarbamate (PDTC). We demonstrate that metal-binding compounds can be subclassified based upon the reversibility of their cytotoxicity by metal supplementation and their modes of action. Understanding the mechanisms whereby metal-binding compounds affect cell behavior may aid in their optimization for clinical use.
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Affiliation(s)
- Wei-Qun Ding
- Department of Pathology, University of Oklahoma Health Sciences Center, 975 NE 10th Street, BRC 411A, Oklahoma City, OK 73104, USA.
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Hellmich HL, Eidson K, Cowart J, Crookshanks J, Boone DK, Shah S, Uchida T, DeWitt DS, Prough DS. Chelation of neurotoxic zinc levels does not improve neurobehavioral outcome after traumatic brain injury. Neurosci Lett 2008; 440:155-9. [PMID: 18556117 DOI: 10.1016/j.neulet.2008.05.068] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 05/16/2008] [Accepted: 05/17/2008] [Indexed: 11/17/2022]
Abstract
Increases of synaptically released zinc and intracellular accumulation of zinc in hippocampal neurons after traumatic or ischemic brain injury is neurotoxic and chelation of zinc has been shown to reduce neurodegeneration. Although our previous studies showed that zinc chelation in traumatically brain-injured rats correlated with an increase in whole-brain expression of several neuroprotective genes and reduced numbers of apoptotic neurons, the effect on functional outcome has not been determined, and the question of whether this treatment may actually be clinically relevant has not been answered. In the present study, we show that treatment of TBI rats with the zinc chelator calcium EDTA reduces the numbers of injured, Fluoro-Jade-positive neurons in the rat hippocampus 24 h after injury but does not improve neurobehavioral outcome (spatial memory deficits) 2 weeks post-injury. Our data suggest that zinc chelation, despite providing short-term histological neuroprotection, fails to improve long-term functional outcome, perhaps because long-term disruptions in homeostatic levels of zinc adversely influence hippocampus-dependent spatial memory.
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Affiliation(s)
- Helen L Hellmich
- Department of Anesthesiology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0830, United States.
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Que EL, Domaille DW, Chang CJ. Metals in neurobiology: probing their chemistry and biology with molecular imaging. Chem Rev 2008; 108:1517-49. [PMID: 18426241 DOI: 10.1021/cr078203u] [Citation(s) in RCA: 1522] [Impact Index Per Article: 95.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Emily L Que
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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Chang DTW, Reynolds IJ. Mitochondrial trafficking and morphology in healthy and injured neurons. Prog Neurobiol 2006; 80:241-68. [PMID: 17188795 DOI: 10.1016/j.pneurobio.2006.09.003] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 09/14/2006] [Accepted: 09/18/2006] [Indexed: 12/21/2022]
Abstract
Mitochondria are the primary generators of ATP and are important regulators of intracellular calcium homeostasis. These organelles are dynamically transported along lengthy neuronal processes, presumably for appropriate distribution to cellular regions of high metabolic demand and elevated intracellular calcium, such as synapses. The removal of damaged mitochondria that produce harmful reactive oxygen species and promote apoptosis is also thought to be mediated by transport of mitochondria to autophagosomes. Mitochondrial trafficking is therefore important for maintaining neuronal and mitochondrial health while cessation of movement may lead to neuronal and mitochondrial dysfunction. Mitochondrial morphology is also dynamic and is remodeled during neuronal injury and disease. Recent studies reveal different manifestations and mechanisms of impaired mitochondrial movement and altered morphology in injured neurons. These are likely to cause varied courses toward neuronal degeneration and death. The goal of this review is to provide an appreciation of the full range of mitochondrial function, morphology and trafficking, and the critical role these parameters play in neuronal physiology and pathophysiology.
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Affiliation(s)
- Diane T W Chang
- Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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Ding WQ, Liu B, Vaught JL, Palmiter RD, Lind SE. Clioquinol and docosahexaenoic acid act synergistically to kill tumor cells. Mol Cancer Ther 2006; 5:1864-72. [PMID: 16891473 DOI: 10.1158/1535-7163.mct-06-0067] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Clioquinol, an 8-hydroxyquinoline derivative (5-chloro-7-iodo-8-hydroxyquinoline) with antimicrobial properties, has recently been found to have cytotoxic activity towards human cancer cell lines at concentrations achieved by oral administration. This study was initiated to determine whether clioquinol could potentiate the antitumor effects of two drugs, doxorubicin and docosahexaenoic acid (DHA), believed to act in part via the generation of reactant oxidant species. At low micromolar concentrations, clioquinol had little effect upon cell viability and did not potentiate doxorubicin's cytotoxicity. Clioquinol significantly enhanced DHA's cytotoxic effects, an interaction that was shown to be synergistic by isobolographic analysis. Clioquinol exhibited a synergistic interaction with DHA in reducing nuclear factor-kappaB activity and inducing apoptosis, and the combination reduced the level of several molecules that promote cell survival, including Akt, p65, and Bcl-2. Interestingly, clioquinol neither induced lipid peroxidation itself nor increased peroxidation brought about by the addition of DHA. However, when cells were pretreated with antioxidant vitamin E, the synergism of clioquinol and DHA was blocked, indicating the essential role of lipid peroxidation for their action. These findings reveal a novel antitumor drug combination that synergistically targets major cell survival signaling pathways.
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Affiliation(s)
- Wei-Qun Ding
- University of Oklahoma Health Sciences Center, 975 Northeast 10th Street, BRC 409, Oklahoma City, OK 73104, USA.
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Tauskela JS, Brunette E, Kiedrowski L, Lortie K, Hewitt M, Morley P. Unconventional neuroprotection against Ca2+ -dependent insults by metalloporphyrin catalytic antioxidants. J Neurochem 2006; 98:1324-42. [PMID: 16895586 DOI: 10.1111/j.1471-4159.2006.03973.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We evaluated whether both inert and catalytically active metalloporphyrin antioxidants, meso-substituted with either phenyl-based or N-alkylpyridinium-based groups, suppress Ca(2+)-dependent neurotoxicity in cell culture models of relevance to cerebral ischemia. Representatives from both metalloporphyrin classes, regardless of antioxidant strength, protected cultured cortical neurons or PC-12 cultures against the Ca(2+) ionophores ionomycin or A23187, by suppressing neurotoxic Ca(2+) influx. Some metalloporphyrins suppressed excitotoxic Ca(2+) influx indirectly induced by the Ca(2+) ionophores in cortical neurons. Metalloporphyrins did not quench intracellular fluorescence, suggesting localization to the plasma membrane interface and/or interference with Ca(2+) ionophores. Metalloporphyrins suppressed ionomycin-induced Mn(2+) influx, but did not protect cortical neurons against pyrithione, a Zn(2+) ionophore. In other Ca(2+)-dependent paradigms, Ca(2+) influx via plasma membrane depolarization, but not through reversal of plasmalemmal Na(+)/Ca(2+) exchangers, was modestly suppressed by Mn(III)meso-tetrakis(4-benzoic acid)porphyrin (Mn(III)TBAP) or by an inert analog, Zn(II)TBAP. Mn(III)TBAP and Zn(II)TBAP potently protected cortical neurons against long-duration oxygen-glucose deprivation (OGD), performed in the presence of antagonists of NMDA, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and L-type voltage-gated Ca(2+) channels, raising the possibility of an unconventional mode of blockade of transient receptor protein melastatin 7 channels by a metalloTBAP family of metalloporphyrins. The present study extends the range of Ca(2+)-dependent insults for which metalloporphyrins demonstrate unconventional neuroprotection. MetalloTBAPs appear capable of targeting an OGD temporal continuum.
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Affiliation(s)
- Joseph S Tauskela
- National Research Council, Institute for Biological Sciences, Synaptic Pathophysiology Group, Ottawa, Ontario, Canada.
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Choi JS, Kim KA, Yoon YJ, Fujikado T, Joo CK. Inhibition of cyclooxygenase-2 expression by zinc-chelator in retinal ischemia. Vision Res 2006; 46:2721-7. [PMID: 16584753 DOI: 10.1016/j.visres.2006.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 01/31/2006] [Accepted: 02/01/2006] [Indexed: 01/26/2023]
Abstract
The zinc ion (Zn2+) is abundant in neurons. However, excessive Zn2+ can induce neuronal cell death. This study examined the role of Zn2+ in transient retinal ischemia in adult male rats. The rats were sacrificed 4-24 h after retinal ischemia by high intra-ocular pressure, and the retinas were prepared for microscopic examination of retinal cell degeneration, and fluorescence microscopy using zinquin ethyl ester as the zinc ion-specific probe. Moreover, COX-2 expression was observed by Western blotting. In control retinas, there was a low Zn2+ concentration in the inner plexiform layer (IPL), a high Zn2+ concentration in the outer plexiform layer (OPL), and no detectable Zn2+ in either the ganglion cell layer (GCL) or the inner nuclear layer (INL). In contrast, in the retinas exposed to ischemia without the administration of the zinc ion chelators (Ca2+-EDTA and TPEN), Zn2+ deposits were found in the IPL and INL beginning 4 h after ischemia and degeneration of neurons was found in the GCL and INL. Less Zn2+ accumulation in the IPL and INL and less neuronal degeneration in the GCL and INL were found in the retinas treated with Ca2+-EDTA or TPEN before ischemia. Furthermore, the COX-2 protein levels increased 4-8 h after retinal ischemia, and chelation of zinc ion inhibited this effect. These results suggest that the accumulation of Zn2+ following an ischemic insult can cause retinal degeneration and induce abnormal COX-2 expression.
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Affiliation(s)
- Jun-Sub Choi
- Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul 137-701, Republic of Korea
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Minami A, Sakurada N, Fuke S, Kikuchi K, Nagano T, Oku N, Takeda A. Inhibition of presynaptic activity by zinc released from mossy fiber terminals during tetanic stimulation. J Neurosci Res 2006; 83:167-76. [PMID: 16342122 DOI: 10.1002/jnr.20714] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Zinc exists in high densities in the giant boutons of hippocampal mossy fibers. On the basis of the evidence that zinc decreases extracellular glutamate concentration in the hippocampus, the presynaptic action of zinc released from mossy fibers during high-frequency (tetanic) stimulation was examined using hippocampal slices. The increase in zinc-specific fluorescent signals was observed in both extracellular and intracellular compartments in the mossy fiber terminals during the delivery of tetanic stimuli (100 Hz, 1 sec) to the dentate granule cell layer, suggesting that zinc released from mossy fibers is immediately retaken up by mossy fibers. When mossy fiber terminals were preferentially double-stained with zinc and calcium indicators and tetanic stimuli (100 Hz, 1 sec) were delivered to the dentate granule cell layer, the increase in calcium orange signal during the stimulation was enhanced in mossy fiber terminals by addition of CaEDTA, a membrane-impermeable zinc chelator, and was suppressed by addition of zinc. The decrease in FM4-64 signal (vesicular exocytosis) during tetanic stimulation (10 Hz, 180 sec), which induced mossy fiber long-term potentiation, was also enhanced in mossy fiber terminals by addition of CaEDTA and was suppressed by addition of zinc. The present study demonstrates that zinc released from mossy fibers may be a negative-feedback factor against presynaptic activity during tetanic stimulation.
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Affiliation(s)
- Akira Minami
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
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Abstract
The use of zinc in medicinal skin cream was mentioned in Egyptian papyri from 2000 BC (for example, the Smith Papyrus), and zinc has apparently been used fairly steadily throughout Roman and modern times (for example, as the American lotion named for its zinc ore, 'Calamine'). It is, therefore, somewhat ironic that zinc is a relatively late addition to the pantheon of signal ions in biology and medicine. However, the number of biological functions, health implications and pharmacological targets that are emerging for zinc indicate that it might turn out to be 'the calcium of the twenty-first century'. Here neurobiological roles of endogenous zinc is summarized.
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Affiliation(s)
- Jae-Yong Koh
- Department of Neurology, University of Ulsan College of Medicine, Seoul, Korea
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31
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Abstract
The use of zinc in medicinal skin cream was mentioned in Egyptian papyri from 2000 BC (for example, the Smith Papyrus), and zinc has apparently been used fairly steadily throughout Roman and modern times (for example, as the American lotion named for its zinc ore, 'Calamine'). It is, therefore, somewhat ironic that zinc is a relatively late addition to the pantheon of signal ions in biology and medicine. However, the number of biological functions, health implications and pharmacological targets that are emerging for zinc indicate that it might turn out to be 'the calcium of the twenty-first century'.
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Abstract
Clioquinol, a metal chelator, has been used for many years as an antimicrobial agent and more recently as a potential treatment for Alzheimer's disease. Because it binds copper and zinc, metals essential for the activity of the enzyme superoxide dismutase-1 (SOD1), a potential target for anticancer drug development, we investigated its effects on human cancer cells. Treatment with clioquinol reduced the viability of eight different human cancer cell lines in a concentration-dependent manner, with IC(50) values in the low micromolar range. Biochemical analysis revealed that clioquinol induced cancer cell death through apoptotic pathways that require caspase activity. Although clioquinol induced modest inhibition of SOD1 activity in treated cells, comparable inhibition by a known SOD1 inhibitor, diethyldithiocarbamate, did not result in cytotoxicity. The addition of copper, iron, or zinc did not rescue cells from cliquinol-induced cytotoxicity but enhanced its killing, arguing against metal chelation as its major mechanism of action. To test if clioquinol might act as an ionophore, a fluorescent probe was used to monitor intracellular zinc concentrations. The addition of clioquinol resulted in elevated levels of intracellular zinc, indicating that clioquinol acts as a zinc ionophore. In an in vivo xenografts mouse model, clioquinol inhibited tumor growth of xenografts over a 6-week period, without inducing visible toxicity. Our results show that clioquinol has anticancer effects both in vitro and in vivo. Transition metal ionophores may be a subclass of metal chelators with anticancer activity deserving of further development.
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Affiliation(s)
- Wei-Qun Ding
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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Lee FY, Huang JJ, Chen YJ, Lin KJ, Lee GH, Peng SM, Ru Hwu J, Lu KL. Os(CO)2(η2-SC5H4N(O))(η2-SC5H4N): structural evidence for the transformation of pyridine-2-thione N-oxide to pyridine-2-thiolate in osmium complexes. J Organomet Chem 2005. [DOI: 10.1016/j.jorganchem.2004.09.064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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