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Liu M, Yu X, Li M, Liao N, Bi A, Jiang Y, Liu S, Gong Z, Zeng W. Fluorescent probes for the detection of magnesium ions (Mg 2+): from design to application. RSC Adv 2018; 8:12573-12587. [PMID: 35541260 PMCID: PMC9079720 DOI: 10.1039/c8ra00946e] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/21/2018] [Indexed: 11/24/2022] Open
Abstract
Magnesium ions (Mg2+) play essential roles in various physiological and pathological processes, its abnormal homeostasis in cells is related to many diseases, such as diabetes, neuromuscular disorders, hypertension and other cardiovascular disorders. Investigation on the regulation of magnesium in cellular processes has attracted considerable interest in the past several decades. Among those reported strategies, fluorescent imaging technology has become a powerful and cost-effective tool for the real-time monitoring of magnesium distribution, uptake and trafficking, due to its superior features of high sensitivity and non-invasiveness, as well as excellent spatial and temporal fidelity. Herein, we critically summarize the progresses in the intracellular magnesium detection with fluorescent imaging probes. Our discussion focuses on the recent contributions concerning fluorescent imaging probes for mapping magnesium in biological processes. All the candidates are organized according to their acceptor structures. The sensing mechanisms of fluorescent probes are also highly taken into account. Challenges, trends and prospects of fluorescent imaging technology in magnesium detection are also set forth.
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Affiliation(s)
- Min Liu
- Department of Pharmacy, Institute of Hospital Pharmacy, Xiangya Hospital, Central South University Changsha 410008 P. R. China
- Xiangya School of Pharmaceutical Sciences, Central South University Changsha 410013 P. R. China +86-731-82650459 +86-731-82650459
| | - Xia Yu
- Xiangya School of Pharmaceutical Sciences, Central South University Changsha 410013 P. R. China +86-731-82650459 +86-731-82650459
| | - Ming Li
- Changsha Stomatological Hospital Changsha 410000 P. R. China
| | - Naixuan Liao
- Xiangya School of Pharmaceutical Sciences, Central South University Changsha 410013 P. R. China +86-731-82650459 +86-731-82650459
| | - Anyao Bi
- Xiangya School of Pharmaceutical Sciences, Central South University Changsha 410013 P. R. China +86-731-82650459 +86-731-82650459
| | - Yueping Jiang
- Department of Pharmacy, Institute of Hospital Pharmacy, Xiangya Hospital, Central South University Changsha 410008 P. R. China
| | - Shao Liu
- Department of Pharmacy, Institute of Hospital Pharmacy, Xiangya Hospital, Central South University Changsha 410008 P. R. China
| | - Zhicheng Gong
- Department of Pharmacy, Institute of Hospital Pharmacy, Xiangya Hospital, Central South University Changsha 410008 P. R. China
| | - Wenbin Zeng
- Xiangya School of Pharmaceutical Sciences, Central South University Changsha 410013 P. R. China +86-731-82650459 +86-731-82650459
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Li CR, Li SL, Wang GQ, Yang ZY. Spectroscopic properties of a chromone-fluorescein conjugate as Mg2+ “turn on” fluorescent probe. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2016.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Bal NV, Susorov D, Chesnokova E, Kasianov A, Mikhailova T, Alkalaeva E, Balaban PM, Kolosov P. Upstream Open Reading Frames Located in the Leader of Protein Kinase Mζ mRNA Regulate Its Translation. Front Mol Neurosci 2016; 9:103. [PMID: 27790092 PMCID: PMC5061749 DOI: 10.3389/fnmol.2016.00103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/30/2016] [Indexed: 12/17/2022] Open
Abstract
For protein synthesis that occurs locally in dendrites, the translational control mechanisms are much more important for neuronal functioning than the transcription levels. Here, we show that uORFs (upstream open reading frames) in the 5′ untranslated region (5′UTR) play a critical role in regulation of the translation of protein kinase Mζ (PKMζ). Elimination of these uORFs activates translation of the reporter protein in vitro and in primary cultures of rat hippocampal neurons. Using cell-free translation systems, we demonstrate that translational initiation complexes are formed only on uORFs. Further, we address the mechanism of translational repression of PKMζ translation, by uORFs. We observed an increase in translation of the reporter protein under the control of PKMζ leader in neuronal culture during non-specific activation by picrotoxin. We also show that such a mechanism is similar to the mechanism seen in cell stress, as application of sodium arsenite to neuron cultures induced translation of mRNA carrying PKMζ 5′UTR similarly to picrotoxin activation. Therefore, we suppose that phosphorylation of eIF2a, like in cell stress, is a main regulator of PKMζ translation. Altogether, our findings considerably extend our understanding of the role of uORF in regulation of PKMζ translation in activated neurons, important at early stages of LTP.
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Affiliation(s)
- Natalia V Bal
- Cellular Neurobiology of Learning Laboratory, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences Moscow, Russia
| | - Denis Susorov
- Laboratory of Mechanisms and Control of Translation, Engelhardt Institute of Molecular Biology, Russian Academy of SciencesMoscow, Russia; Faculty of Bioengineering and Bioinformatics, M. V. Lomonosov Moscow State UniversityMoscow, Russia
| | - Ekaterina Chesnokova
- Cellular Neurobiology of Learning Laboratory, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences Moscow, Russia
| | - Artem Kasianov
- Laboratory of System Biology and Computational Genetics, Vavilov Institute of General Genetics, Russian Academy of Sciences Moscow, Russia
| | - Tatiana Mikhailova
- Laboratory of Mechanisms and Control of Translation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences Moscow, Russia
| | - Elena Alkalaeva
- Laboratory of Mechanisms and Control of Translation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences Moscow, Russia
| | - Pavel M Balaban
- Cellular Neurobiology of Learning Laboratory, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences Moscow, Russia
| | - Peter Kolosov
- Cellular Neurobiology of Learning Laboratory, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences Moscow, Russia
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Suzuki Y, Yokoyama K. Development of Functional Fluorescent Molecular Probes for the Detection of Biological Substances. BIOSENSORS 2015; 5:337-63. [PMID: 26095660 PMCID: PMC4493553 DOI: 10.3390/bios5020337] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 01/27/2023]
Abstract
This review is confined to sensors that use fluorescence to transmit biochemical information. Fluorescence is, by far, the most frequently exploited phenomenon for chemical sensors and biosensors. Parameters that define the application of such sensors include intensity, decay time, anisotropy, quenching efficiency, and luminescence energy transfer. To achieve selective (bio)molecular recognition based on these fluorescence phenomena, various fluorescent elements such as small organic molecules, enzymes, antibodies, and oligonucleotides have been designed and synthesized over the past decades. This review describes the immense variety of fluorescent probes that have been designed for the recognitions of ions, small and large molecules, and their biological applications in terms of intracellular fluorescent imaging techniques.
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Affiliation(s)
- Yoshio Suzuki
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba 305-8566, Japan.
| | - Kenji Yokoyama
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
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Palacios-Prado N, Huetteroth W, Pereda AE. Hemichannel composition and electrical synaptic transmission: molecular diversity and its implications for electrical rectification. Front Cell Neurosci 2014; 8:324. [PMID: 25360082 PMCID: PMC4197764 DOI: 10.3389/fncel.2014.00324] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/26/2014] [Indexed: 11/29/2022] Open
Abstract
Unapposed hemichannels (HCs) formed by hexamers of gap junction proteins are now known to be involved in various cellular processes under both physiological and pathological conditions. On the other hand, less is known regarding how differences in the molecular composition of HCs impact electrical synaptic transmission between neurons when they form intercellular heterotypic gap junctions (GJs). Here we review data indicating that molecular differences between apposed HCs at electrical synapses are generally associated with rectification of electrical transmission. Furthermore, this association has been observed at both innexin and connexin (Cx) based electrical synapses. We discuss the possible molecular mechanisms underlying electrical rectification, as well as the potential contribution of intracellular soluble factors to this phenomenon. We conclude that asymmetries in molecular composition and sensitivity to cellular factors of each contributing hemichannel can profoundly influence the transmission of electrical signals, endowing electrical synapses with more complex functional properties.
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Affiliation(s)
- Nicolás Palacios-Prado
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA ; Marine Biological Laboratory, Woods Hole Massachusetts, MA, USA
| | - Wolf Huetteroth
- Marine Biological Laboratory, Woods Hole Massachusetts, MA, USA ; Department of Neurobiology, University of Konstanz Konstanz, Germany
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA ; Marine Biological Laboratory, Woods Hole Massachusetts, MA, USA
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Palacios-Prado N, Chapuis S, Panjkovich A, Fregeac J, Nagy JI, Bukauskas FF. Molecular determinants of magnesium-dependent synaptic plasticity at electrical synapses formed by connexin36. Nat Commun 2014; 5:4667. [PMID: 25135336 PMCID: PMC4142521 DOI: 10.1038/ncomms5667] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/11/2014] [Indexed: 01/28/2023] Open
Abstract
Neuronal gap junction (GJ) channels composed of connexin36 (Cx36) play an important role in neuronal synchronization and network dynamics. Here we show that Cx36-containing electrical synapses between inhibitory neurons of the thalamic reticular nucleus are bidirectionally modulated by changes in intracellular free magnesium concentration ([Mg(2+)]i). Chimeragenesis demonstrates that the first extracellular loop of Cx36 contains a Mg(2+)-sensitive domain, and site-directed mutagenesis shows that the pore-lining residue D47 is critical in determining high Mg(2+)-sensitivity. Single-channel analysis of Mg(2+)-sensitive chimeras and mutants reveals that [Mg(2+)]i controls the strength of electrical coupling mostly via gating mechanisms. In addition, asymmetric transjunctional [Mg(2+)]i induces strong instantaneous rectification, providing a novel mechanism for electrical rectification in homotypic Cx36 GJs. We suggest that Mg(2+)-dependent synaptic plasticity of Cx36-containing electrical synapses could underlie neuronal circuit reconfiguration via changes in brain energy metabolism that affects neuronal levels of intracellular ATP and [Mg(2+)]i.
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Affiliation(s)
- Nicolás Palacios-Prado
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
- Grass Laboratory, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Sandrine Chapuis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| | - Alejandro Panjkovich
- European Molecular Biology Laboratory, Hamburg Outstation, 22603 Hamburg, Germany
| | - Julien Fregeac
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| | - James I. Nagy
- Department of Physiology, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Feliksas F. Bukauskas
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
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Ozdogan L, Sastim H, Ornek D, Postaci A, Ayerden T, Dikmen B. Neurotoxic effects of intrathecal magnesium sulphate. Rev Bras Anestesiol 2014; 63:139-43. [PMID: 23438808 DOI: 10.1016/s0034-7094(13)70205-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 02/27/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND OBJECTIVES To assess the potential neurotoxic effects at the ultrastructural level of magnesium sulfate administered intrathecally as a single or multi-dose. METHODS Our study was conducted with 24 Sprague-Dawley rats that weighed 250-300 g. After a 4-hour fast, the rats were given 10 mg.kg(-1) xylazine chloride intraperitoneal and then randomly allocated into three groups. Group I (n=8) received 0.9% normal saline, Group II (n = 8) was given one intrathecal injection of 0.02 mL of 15% magnesium sulphate, and Group III (n = 8) was given 0.02 mL of 15% magnesium sulphate once a day for seven days. The injections were given within 0.40 × 50 mm from the lumbar area. After seven days, the animals were sacrificed under anesthesia with an aortic injection of 10% formaldehyde and their tissues were fixed. The medulla spinalis was then examined and histopathologically evaluated under an electron microscope. The Kruskal-Wallis test was used for statistical evaluation. A value of p < .05 was considered to be statistically significant. RESULTS Significant neurodegeneration was detected in rats given single or repeated magnesium sulphate injections compared to the control group. The histopathological evaluation score of this group was also high. CONCLUSIONS Based on electron microscopic examination, we found that intrathecal magnesium sulphate administration induced neurodegeneration.
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Affiliation(s)
- Levent Ozdogan
- Anaesthesia and Reanimation Department, Ankara Numune Training and Research Hospital, Turkey
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Neurotoxic effects of intrathecal magnesium sulphate. Braz J Anesthesiol 2013; 63:139-43. [PMID: 24565097 DOI: 10.1016/j.bjane.2012.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 02/27/2012] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND AND OBJECTIVES To assess the potential neurotoxic effects at the ultrastructural level of magnesium sulfate administered intrathecally as a single or multi-dose. METHODS Our study was conducted with 24 Sprague-Dawley rats that weighed 250-300 g. After a 4-hour fast, the rats were given 10 mg.kg(-1) xylazine chloride intraperitoneal and then randomly allocated into three groups. Group I (n = 8) received 0.9% normal saline, Group II (n = 8) was given one intrathecal injection of 0.02 mL of 15% magnesium sulphate, and Group III (n = 8) was given 0.02 mL of 15% magnesium sulphate once a day for seven days. The injections were given within 0.40x50 mm from the lumbar area. After seven days, the animals were sacrificed under anesthesia with an aortic injection of 10% formaldehyde and their tissues were fixed. The medulla spinalis was then examined and histopathologically evaluated under an electron microscope. The Kruskal-Wallis test was used for statistical evaluation. A value of p < .05 was considered to be statistically significant. RESULTS Significant neurodegeneration was detected in rats given single or repeated magnesium sulphate injections compared to the control group. The histopathological evaluation score of this group was also high. CONCLUSIONS Based on electron microscopic examination, we found that intrathecal magnesium sulphate administration induced neurodegeneration.
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Murck H. Ketamine, magnesium and major depression--from pharmacology to pathophysiology and back. J Psychiatr Res 2013; 47:955-65. [PMID: 23541145 DOI: 10.1016/j.jpsychires.2013.02.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 02/14/2013] [Accepted: 02/26/2013] [Indexed: 01/08/2023]
Abstract
UNLABELLED The glutamatergic mechanism of antidepressant treatments is now in the center of research to overcome the limitations of monoamine-based approaches. There are several unresolved issues. For the action of the model compound, ketamine, NMDA-receptor block, AMPA-receptor activation and BDNF release appear to be involved in a mechanism, which leads to synaptic sprouting and strengthened synaptic connections. The link to the pathophysiology of depression is not clear. An overlooked connection is the role of magnesium, which acts as physiological NMDA-receptor antagonist: 1. There is overlap between the actions of ketamine with that of high doses of magnesium in animal models, finally leading to synaptic sprouting. 2. Magnesium and ketamine lead to synaptic strengthening, as measured by an increase in slow wave sleep in humans. 3. Pathophysiological mechanisms, which have been identified as risk factors for depression, lead to a reduction of (intracellular) magnesium. These are neuroendocrine changes (increased cortisol and aldosterone) and diabetes mellitus as well as Mg(2+) deficiency. 4. Patients with therapy refractory depression appear to have lower CNS Mg(2+) levels in comparison to health controls. 5. Experimental Mg(2+) depletion leads to depression- and anxiety like behavior in animal models. 6. Ketamine, directly or indirectly via non-NMDA glutamate receptor activation, acts to increase brain Mg(2+) levels. Similar effects have been observed with other classes of antidepressants. 7. Depressed patients with low Mg(2+) levels tend to be therapy refractory. Accordingly, administration of Mg(2+) either alone or in combination with standard antidepressants acts synergistically on depression like behavior in animal models. CONCLUSION On the basis of the potential pathophysiological role of Mg(2+)-regulation, it may be possible to predict the action of ketamine and of related compounds based on Mg(2+) levels. Furthermore, screening for compounds to increase neuronal Mg(2+) concentration could be a promising instrument to identify new classes of antidepressants. Overall, any discussion of the glutamatergic system in affective disorders should consider the role of Mg(2+).
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Two independent switches regulate cytoplasmic dynein's processivity and directionality. Proc Natl Acad Sci U S A 2012; 109:5289-93. [PMID: 22411823 DOI: 10.1073/pnas.1116315109] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Cytoplasmic dynein is a microtubule-based molecular motor that participates in a multitude of cell activities, from cell division to organelle transport. Unlike kinesin and myosin, where different tasks are performed by highly specialized members of these superfamilies, a single form of the dynein heavy chain is utilized for different functions. This versatility demands an extensive regulation of motor function. Using an improved application of an optical trap, we were now able to demonstrate that cytoplasmic dynein can generate a discrete power stroke as well as a processive walk in either direction; i.e., towards the plus- or towards the minus-end of a microtubule. Thus, dynein's motor functions can be described by four basic modes of motion: processive and nonprocessive movement, and movement in the forward and reverse directions. Importantly, these four modes of movement can be controlled by two switches. One switch, based on phosphate, determines the directionality of movement. The second switch, depending on magnesium, converts cytoplasmic dynein from a nonprocessive to a processive motor. The two switches can be triggered separately or jointly by changing concentrations of phosphate and magnesium in the local environment. The control of four modes of movement by two switches has major implications for our understanding of the cellular functions and regulation of cytoplasmic dynein. Based on recent studies of dynein's structure we are able to draw new conclusions on cytoplasmic dynein's stepping mechanism.
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Shindo Y, Fujimoto A, Hotta K, Suzuki K, Oka K. Glutamate-induced calcium increase mediates magnesium release from mitochondria in rat hippocampal neurons. J Neurosci Res 2010; 88:3125-32. [DOI: 10.1002/jnr.22467] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Singh N, Kaur N, Mulrooney RC, Callan JF. A ratiometric fluorescent probe for magnesium employing excited state intramolecular proton transfer. Tetrahedron Lett 2008. [DOI: 10.1016/j.tetlet.2008.09.052] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Park EJ, Brasuel M, Behrend C, Philbert MA, Kopelman R. Ratiometric optical PEBBLE nanosensors for real-time magnesium ion concentrations inside viable cells. Anal Chem 2004; 75:3784-91. [PMID: 14572044 DOI: 10.1021/ac0342323] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper presents the development and characterization of a highly selective magnesium fluorescent optical nanosensor, made possible by PEBBLE (probe encapsulated by biologically localized embedding) technology. A ratiometric sensor has been developed by co-immobilizing a dye that is sensitive to and highly selective for magnesium, with a reference dye in a matrix. The sensors are prepared via a microemulsion polymerization process, which entraps the sensing components inside a polymer matrix. The resultant spherical sensors are approximately 40 nm in diameter. The Coumarin 343 (C343) dye, which by itself does not enter the cell, when immobilized in a PEBBLE is used as the magnesium-selective agent that provides the high and necessary selectivity over other intracellular ions, such as Ca2+, Na+, and K+. The dynamic range of these sensors was 1-30 mM, with a linear range from 1 to 10 mM, with a response time of <4 s. In contrast to free dye, these nano-optodes are not perturbed by proteins. They are fully reversible and exhibit minimal leaching and photobleaching over extended periods of time. In vitro intracellular changes in Mg2+ concentration were monitored in C6 glioma cells, which remained viable after PEBBLE delivery via gene gun injection. The selectivity for Mg2+ along with the biocompatibility of the matrix provides a new and reliable tool for intracellular magnesium measurements.
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Affiliation(s)
- Edwin J Park
- Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109, USA
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Layden BT, Abukhdeir AM, Williams N, Fonseca CP, Carroll L, Castro MMCA, Geraldes CFGC, Bryant FB, Freitas DMD. Effects of Li+ transport and Li+ immobilization on Li+/Mg2+ competition in cells: implications for bipolar disorder. Biochem Pharmacol 2003; 66:1915-24. [PMID: 14599549 DOI: 10.1016/j.bcp.2003.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Li(+)/Mg(2+) competition has been implicated in the therapeutic action of Li(+) treatment in bipolar illness. We hypothesized that this competition depended on cell-specific properties. To test this hypothesis, we determined the degree of Li(+) transport, immobilization, and Li(+)/Mg(2+) competition in lymphoblastomas, neuroblastomas, and erythrocytes. During a 50 mM/L Li(+)-loading incubation, Li(+) accumulation at 30 min (mmoles Li(+)/L cells) was the greatest in lymphoblastomas (11.1+/-0.3), followed by neuroblastomas (9.3+/-0.5), and then erythrocytes (4.0+/-0.5). Li(+) binding affinities to the plasma membrane in all three cell types were of the same order of magnitude; however, Li(+) immobilization in intact cells was greatest in neuroblastomas and least in erythrocytes. When cells were loaded for 30 min in a 50 mM/L Li(+)-containing medium, the percentage increase in free intracellular [Mg(2+)] in neuroblastoma and lymphoblastoma cells ( approximately 55 and approximately 52%, respectively) was similar, but erythrocytes did not exhibit any substantial increase ( approximately 6%). With the intracellular [Li(+)] at 15 mM/L, the free intracellular [Mg(2+)] increased by the greatest amount in neuroblastomas ( approximately 158%), followed by lymphoblastomas ( approximately 75%), and then erythrocytes ( approximately 50%). We conclude that Li(+) immobilization and transport are related to free intracellular [Mg(2+)] and to the extent of Li(+)/Mg(2+) competition in a cell-specific manner.
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Affiliation(s)
- Brian T Layden
- Department of Chemistry, Loyola University Chicago, 6525 N. Sheridan Rd., Chicago, IL 60626, USA
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Kubota T, Tokuno K, Nakagawa J, Kitamura Y, Ogawa H, Suzuki Y, Suzuki K, Oka K. Na+/Mg2+ transporter acts as a Mg2+ buffering mechanism in PC12 cells. Biochem Biophys Res Commun 2003; 303:332-6. [PMID: 12646207 DOI: 10.1016/s0006-291x(03)00346-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Mg(2+) buffering mechanisms in PC12 cells were demonstrated with particular focus on the role of the Na(+)/Mg(2+) transporter by using a newly developed Mg(2+) indicator, KMG-20, and also a Na(+) indicator, Sodium Green. Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), a protonophore, induced a transient increase in the intracellular Mg(2+) concentration ([Mg(2+)](i)). The rate of decrease of [Mg(2+)](i) was slower in a Na(+)-free extracellular medium, suggesting the coupling of Na(+) influx and Mg(2+) efflux. Na(+) influxes were different for normal and imipramine- (a putative inhibitor of the Na(+)/Mg(2+) transporter) containing solutions. FCCP induced a rapid increase in [Na(+)](i) in the normal solution, while the increase was gradual in the imipramine-containing solution. The rate of decrease of [Mg(2+)](i) in the imipramine-containing solution was also slower than that in the normal solution. From these results, we show that the main buffering mechanism for excess Mg(2+) depends on the Na(+)/Mg(2+) transporter in PC12 cells.
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Affiliation(s)
- Takeshi Kubota
- School of Fundamental Science and Technology, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan
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