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Fujita K, Shindo Y, Katsuta Y, Goto M, Hotta K, Oka K. Intracellular Mg 2+ protects mitochondria from oxidative stress in human keratinocytes. Commun Biol 2023; 6:868. [PMID: 37620401 PMCID: PMC10449934 DOI: 10.1038/s42003-023-05247-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 08/15/2023] [Indexed: 08/26/2023] Open
Abstract
Reactive oxygen species (ROS) are harmful for the human body, and exposure to ultraviolet irradiation triggers ROS generation. Previous studies have demonstrated that ROS decrease mitochondrial membrane potential (MMP) and that Mg2+ protects mitochondria from oxidative stress. Therefore, we visualized the spatio-temporal dynamics of Mg2+ in keratinocytes (a skin component) in response to H2O2 (a type of ROS) and found that it increased cytosolic Mg2+ levels. H2O2-induced responses in both Mg2+ and ATP were larger in keratinocytes derived from adults than in keratinocytes derived from newborns, and inhibition of mitochondrial ATP synthesis enhanced the H2O2-induced Mg2+ response, indicating that a major source of Mg2+ was dissociation from ATP. Simultaneous imaging of Mg2+ and MMP revealed that larger Mg2+ responses corresponded to lower decreases in MMP in response to H2O2. Moreover, Mg2+ supplementation attenuated H2O2-induced cell death. These suggest the potential of Mg2+ as an active ingredient to protect skin from oxidative stress.
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Affiliation(s)
- Keigo Fujita
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Yutaka Shindo
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
- School of Frontier Engineering, Kitasato University, Sagamihara, Japan
| | - Yuji Katsuta
- MIRAI Technology Institute, Shiseido Co. Ltd., Yokohama, Japan
| | - Makiko Goto
- MIRAI Technology Institute, Shiseido Co. Ltd., Yokohama, Japan
| | - Kohji Hotta
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Kotaro Oka
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan.
- School of Frontier Engineering, Kitasato University, Sagamihara, Japan.
- Waseda Research Institute for Science and Engineering, Waseda University, Tokyo, Japan.
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan.
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Mo X, Pang P, Wang Y, Jiang D, Zhang M, Li Y, Wang P, Geng Q, Xie C, Du HN, Zhong B, Li D, Yao J. Tyrosine phosphorylation tunes chemical and thermal sensitivity of TRPV2 ion channel. eLife 2022; 11:78301. [PMID: 35686730 PMCID: PMC9282855 DOI: 10.7554/elife.78301] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/09/2022] [Indexed: 11/21/2022] Open
Abstract
Transient receptor potential vanilloid 2 (TRPV2) is a multimodal ion channel implicated in diverse physiopathological processes. Its important involvement in immune responses has been suggested such as in the macrophages’ phagocytosis process. However, the endogenous signaling cascades controlling the gating of TRPV2 remain to be understood. Here, we report that enhancing tyrosine phosphorylation remarkably alters the chemical and thermal sensitivities of TRPV2 endogenously expressed in rat bone marrow-derived macrophages and dorsal root ganglia (DRG) neurons. We identify that the protein tyrosine kinase JAK1 mediates TRPV2 phosphorylation at the molecular sites Tyr(335), Tyr(471), and Tyr(525). JAK1 phosphorylation is required for maintaining TRPV2 activity and the phagocytic ability of macrophages. We further show that TRPV2 phosphorylation is dynamically balanced by protein tyrosine phosphatase non-receptor type 1 (PTPN1). PTPN1 inhibition increases TRPV2 phosphorylation, further reducing the activation temperature threshold. Our data thus unveil an intrinsic mechanism where the phosphorylation/dephosphorylation dynamic balance sets the basal chemical and thermal sensitivity of TRPV2. Targeting this pathway will aid therapeutic interventions in physiopathological contexts. All the cells in our body have a membrane that separates their interior from the outside environment. However, studded across this barrier are numerous ion channels which allow the cell to sense and react to changes in its surroundings. This includes the ion channel TRPV2, which opens in response to mechanical pressure, certain chemical signals, or rising temperature levels. Many types of cell express TRPV2, including cells in the nervous system, muscle, and the immune system. However, despite being extensively studied, it is still not clear how TRPV2 opens and closes upon encountering high temperatures. In particular, previous work suggested that TRPV2 only responds when a cell’s surroundings reach around 52°C, which is a much higher temperature than cells inside our body normally encounter, even during a fever. To help resolve this mystery, Mo, Pang et al. studied TRPV2 in neurons responsible for sending sensory information and in immune cells called macrophages which had been extracted from rodents and grown in the laboratory. They found that when the cells were bathed in solutions containing magnesium ions, their TRPV2 channels were more sensitive to a number of different cues, including temperature. Further biochemical experiments showed that magnesium ions do not directly affect TRPV2, but increase the activity of another protein called JAK1. The magnesium ions caused JAK1 to attach specialized structures called phosphorylation tags to TRPV2. This modification (known as phosphorylation) made the channel more sensitive, allowing it to open in response to temperatures as low as 40°C. Mo, Pang et al. found that inhibiting JAK1 reduced the activity of TRPV2. Conversely, inhibiting the enzyme that removes the phosphorylation tags, called PTPN1, increased the channel’s activity. They also discovered that when JAK1 was blocked, macrophages were less able to ‘eat up’ bacteria, which is one of their main roles in the immune system. Taken together these experiments advance our understanding of how TRPV2 becomes active. The balance between the phosphorylation by JAK1 and the dephosphorylation by PTPN1 controls the temperature at which TRPV2 opens. Since TRPV2 contributes to several biological functions, including the development of the nervous system, the maintenance of heart muscles, and inflammation, these findings will be important to scientists in a broad range of fields.
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Affiliation(s)
- Xiaoyi Mo
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Peiyuan Pang
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Yulin Wang
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Dexiang Jiang
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Mengyu Zhang
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Yang Li
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Peiyu Wang
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Qizhi Geng
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Chang Xie
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Hai-Ning Du
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Bo Zhong
- Department of Anesthesiology, Wuhan University, Wuhan, China
| | - Dongdong Li
- Neuroscience Paris Seine, CNRS, INSERM, Sorbonne Université, Paris, France
| | - Jing Yao
- Department of Anesthesiology, Wuhan University, Wuhan, China
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Wu J, Meng QH. Current understanding of the metabolism of micronutrients in chronic alcoholic liver disease. World J Gastroenterol 2020; 26:4567-4578. [PMID: 32884217 PMCID: PMC7445863 DOI: 10.3748/wjg.v26.i31.4567] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/22/2020] [Accepted: 07/30/2020] [Indexed: 02/06/2023] Open
Abstract
Alcoholic liver disease (ALD) remains an important health problem worldwide. Perturbation of micronutrients has been broadly reported to be a common characteristic in patients with ALD, given the fact that micronutrients often act as composition or coenzymes of many biochemical enzymes responsible for the inflammatory response, oxidative stress, and cell proliferation. Mapping the metabolic pattern and the function of these micronutrients is a prerequisite before targeted intervention can be delivered in clinical practice. Recent years have registered a significant improvement in our understanding of the role of micronutrients on the pathogenesis and progression of ALD. However, how and to what extent these micronutrients are involved in the pathophysiology of ALD remains largely unknown. In the current study, we provide a review of recent studies that investigated the imbalance of micronutrients in patients with ALD with a focus on zinc, iron, copper, magnesium, selenium, vitamin D and vitamin E, and determine how disturbances in micronutrients relates to the pathophysiology of ALD. Overall, zinc, selenium, vitamin D, and vitamin E uniformly exhibited a deficiency, and iron demonstrated an elevated trend. While for copper, both an elevation and deficiency were observed from existing literature. More importantly, we also highlight several challenges in terms of low sample size, study design discrepancies, sample heterogeneity across studies, and the use of machine learning approaches.
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Affiliation(s)
- Jing Wu
- Department of Critical Care Medicine of Liver Disease, Beijing You-An Hospital, Capital Medical University, Beijing 100069, China
| | - Qing-Hua Meng
- Department of Critical Care Medicine of Liver Disease, Beijing You-An Hospital, Capital Medical University, Beijing 100069, China
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Host-microbiota interaction helps to explain the bottom-up effects of climate change on a small rodent species. ISME JOURNAL 2020; 14:1795-1808. [PMID: 32313262 PMCID: PMC7305154 DOI: 10.1038/s41396-020-0646-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/18/2020] [Accepted: 03/24/2020] [Indexed: 01/02/2023]
Abstract
The population cycles of small rodents have puzzled biologists for centuries. There is a growing recognition of the cascading effects of climate change on the population dynamics of rodents. However, the ultimate cause for the bottom-up effects of precipitation is poorly understood, from a microbial perspective. Here, we conducted a precipitation manipulation experiment in the field, and three feeding trials with controlled diets in the laboratory. We found precipitation supplementation facilitated the recovery of a perennial rhizomatous grass (Leymus chinensis) species, which altered the diet composition and increase the intake of fructose and fructooligosaccharides for Brandt’s vole. Lab results showed that this nutrient shift was accompanied by the modulation of gut microbiota composition and functional pathways (especially for the degradation or biosynthesis of L-histidine). Particularly, the relative abundance of Eubacterium hallii was consistently increased after feeding voles with more L. chinensis, fructose or fructooligosaccharide. These modulations ultimately increased the production of short chain fatty acids (SCFAs) and boosted the growth of vole. This study provides evidence that the precipitation pulses cascades through the plant community to affect rodent gut microbiome. Our results highlight the importance of considering host-microbiota interaction when investigating rodent population responses to climate change.
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Huang H, Liao J, Zheng X, Chen Y, Ren H. Low-level free nitrous acid efficiently inhibits the conjugative transfer of antibiotic resistance by altering intracellular ions and disabling transfer apparatus. WATER RESEARCH 2019; 158:383-391. [PMID: 31059932 DOI: 10.1016/j.watres.2019.04.046] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
Recently, the dissemination of antibiotic resistance genes (ARGs) via plasmid-mediated conjugation has been reported to be facilitated by a series of contaminants. This has highlighted potential challenges to the effective control of this principal mode of horizontal transfer. In the present study, we found that low levels (<0.02 mgN/L) of free nitrous acid (FNA) remarkably inhibited (over 90%) the conjugative transfer of plasmid RP4, a model broad-host-range plasmid, between Escherichia coli. The antimicrobial role of FNA at the applied dosages was firstly ruled out, since no dramatic reductions in viabilities of donor or recipient were observed. Instead, FNA appeared to reduce the available intracellular free Mg2+, which was confirmed to be triggered by the liberation of intracellular Fe2+. These alterations in intracellular Mg2+ and Fe2+ concentrations were found to significantly limit the available energy for conjugative transfer through suppression of glycolysis by decreasing the activities of glycogen phosphorylase and glyceraldehyde-3-phosphate dehydrogenase and also by diverting the glycolytic flux into the pentose phosphate pathway via activation of glucose-6-phosphate dehydrogenase towards the generation of NADPH rather than ATP. Moreover, RP4-encoding genes responsible for DNA transfer and replication (traI, traJ and trfAp), coupling (traG) and mating pair formation (traF and trbBp) were all significantly down-regulated after FNA treatment, indicating that the transfer apparatus required for plasmid processing and delivery was deactivated. By validating the inhibitory effects of FNA on conjugation in real wastewater, this study highlights a promising method for controlling the dissemination of ARGs in systems such as wastewater treatment plants.
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Affiliation(s)
- Haining Huang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Junqi Liao
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Xiong Zheng
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Yinguang Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210093, Jiangsu, PR China
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Carvalho J, Alves S, Castro MMCA, Geraldes CFGC, Queiroz JA, Fonseca CP, Cruz C. Development of a bioreactor system for cytotoxic evaluation of pharmacological compounds in living cells using NMR spectroscopy. J Pharmacol Toxicol Methods 2018; 95:70-78. [PMID: 30502390 DOI: 10.1016/j.vascn.2018.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/26/2018] [Accepted: 11/21/2018] [Indexed: 01/22/2023]
Abstract
INTRODUCTION The evaluation of drug's cytotoxicity is a crucial step in the development of new pharmacological compounds. 31P NMR can be a tool for toxicological screening, as it enables the study of drugs' cytotoxicity and their effect on cell energy metabolism in a real-time, in a non- invasive and non-destructive way. This paper details a step-by-step protocol to implement a bioreactor system able to maintain cell viability during NMR acquisitions, at high cell densities and for several hours, enabling toxicological evaluation of pharmacological compounds in living cells. METHOD HeLa cells were immobilized in agarose gel threads and continuously perfused with oxygenated medium inside a 5 mm NMR tube. Signals corresponding to intracellular high-energy phosphorous compounds were continuously monitored by 31P NMR to assess cell energy levels, intracellular pH and intracellular free Mg2+ concentrations ([Mg2+]f) under control and in the presence of two different cytotoxic drugs, calix-NH2 or 5-fluorouracil (5-FU). RESULTS The bioreactor system was effective in maintaining cell energy levels as well as intracellular pH and [Mg2+]f along time, with a good 31P NMR signal to noise ratio. Calix-NH2 and 5-FU decreased cell energy levels by 35% and 39%, respectively, with a negligible increase in intracellular [Mg2+]f, and without affecting intracellular pH. DISCUSSION The immobilization and perfusion system here detailed, along with 31P NMR, is useful in toxicological evaluation of new pharmacological compounds, enabling the continuous assessment of drugs' effect on energy levels, intracellular pH and [Mg2+]f in intact cells, for several hours without compromising cell viability.
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Affiliation(s)
- Josué Carvalho
- CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, Covilhã, Portugal
| | - Sara Alves
- CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, Covilhã, Portugal
| | - M Margarida C A Castro
- Department of Life Sciences, Faculty of Science and Technology, Coimbra Chemistry Center - CQC, University of Coimbra, Coimbra, Portugal
| | - Carlos F G C Geraldes
- Department of Life Sciences, Faculty of Science and Technology, Coimbra Chemistry Center - CQC, University of Coimbra, Coimbra, Portugal
| | - João A Queiroz
- CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, Covilhã, Portugal
| | - Carla P Fonseca
- CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, Covilhã, Portugal.
| | - Carla Cruz
- CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, Covilhã, Portugal.
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Yu Q, Gao P, Zhang KY, Tong X, Yang H, Liu S, Du J, Zhao Q, Huang W. Luminescent gold nanocluster-based sensing platform for accurate H 2S detection in vitro and in vivo with improved anti-interference. LIGHT, SCIENCE & APPLICATIONS 2017; 6:e17107. [PMID: 30167221 PMCID: PMC6062025 DOI: 10.1038/lsa.2017.107] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 06/22/2017] [Accepted: 06/23/2017] [Indexed: 05/05/2023]
Abstract
Gold nanoclusters (Au NCs) are promising luminescent nanomaterials due to their outstanding optical properties. However, their relatively low quantum yields and environment-dependent photoluminescence properties have limited their biological applications. To address these problems, we developed a novel strategy to prepare chitosan oligosaccharide lactate (Chi)-functionalized Au NCs (Au NCs@Chi), which exhibited emission with enhanced quantum yield and elongated emission lifetime as compared to the Au NCs, as well as exhibited environment-independent photoluminescence properties. In addition, utilizing the free amino groups of Chi onto Au NCs@Chi, we designed a FRET-based sensing platform for the detection of hydrogen sulfide (H2S). The Au NCs and the specific H2S-sensitive merocyanine compound were respectively employed as an energy donor and acceptor in the platform. The addition of H2S induced changes in the emission profile and luminescence lifetime of the platform with high sensitivity and selectivity. Utilization of the platform was demonstrated to detect exogenous and endogenous H2S in vitro and in vivo through wavelength-ratiometric and time-resolved luminescence imaging (TLI). Compared to previously reported luminescent molecules, the platform was less affected by experimental conditions and showed minimized autofluorescence interference and improved accuracy of detection.
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Affiliation(s)
- Qi Yu
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Pengli Gao
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Kenneth Yin Zhang
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Xiao Tong
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Huiran Yang
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Shujuan Liu
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Jing Du
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Qiang Zhao
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Wei Huang
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 211816, China
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Matsui Y, Funato Y, Imamura H, Miki H, Mizukami S, Kikuchi K. Visualization of long-term Mg 2+ dynamics in apoptotic cells using a novel targetable fluorescent probe. Chem Sci 2017; 8:8255-8264. [PMID: 29619172 PMCID: PMC5858021 DOI: 10.1039/c7sc03954a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Accepted: 10/04/2017] [Indexed: 01/30/2023] Open
Abstract
Long-term Mg2+ imaging during apoptosis using a HaloTag-coupled Mg2+ probe demonstrated a Mg2+ concentration increase caused by dissociation of Mg2+ from ATP.
Mg2+ plays important roles in many physiological processes. However, the underlying molecular mechanisms, especially in the apoptotic pathway, remain unclear due to the diffusion of Mg2+ probes, which hinders long-term imaging in specific organelles. We developed an immobilized Mg2+ probe, MGH, which is covalently conjugated with the HaloTag protein in various organelles. HaloTag-coupled MGH enabled long-term imaging of intracellular local Mg2+ dynamics for 24 h. To exploit this remarkable property, MGH was applied to the investigation of intracellular Mg2+ dynamics during apoptosis. Time-lapse imaging revealed an increase in the Mg2+ concentration after apoptotic cell shrinkage. Combined imaging analyses of intracellular Mg2+ and ATP concentrations strongly suggested that this Mg2+ concentration increase was caused by the dissociation of Mg2+ from ATP, along with a decrease in the intracellular ATP concentration. Thus, this protein-coupled Mg2+ probe could be a new chemical tool to elucidate intracellular Mg2+ dynamics with high spatiotemporal resolution.
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Affiliation(s)
- Yusuke Matsui
- Department of Material and Life Science , Graduate School of Engineering , Osaka University , Suita , Osaka 565-0871 , Japan .
| | - Yosuke Funato
- Department of Cellular Regulation , Research Institute for Microbial Diseases , Osaka University , Suita , Osaka 565-0871 , Japan
| | - Hiromi Imamura
- Graduate School of Biostudies , Kyoto University , Kyoto 606-8501 , Japan
| | - Hiroaki Miki
- Department of Cellular Regulation , Research Institute for Microbial Diseases , Osaka University , Suita , Osaka 565-0871 , Japan
| | - Shin Mizukami
- Institute of Multidisciplinary Research for Advanced Materials , Tohoku University , Sendai , Miyagi 980-8577 , Japan .
| | - Kazuya Kikuchi
- Department of Material and Life Science , Graduate School of Engineering , Osaka University , Suita , Osaka 565-0871 , Japan . .,Immunology Frontier Research Center , Osaka University , Suita , Osaka 565-0871 , Japan
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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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García-Sacristán A, Moreno M, Ariza-Mateos A, López-Camacho E, Jáudenes RM, Vázquez L, Gómez J, Martín-Gago JÁ, Briones C. A magnesium-induced RNA conformational switch at the internal ribosome entry site of hepatitis C virus genome visualized by atomic force microscopy. Nucleic Acids Res 2014; 43:565-80. [PMID: 25510496 PMCID: PMC4288189 DOI: 10.1093/nar/gku1299] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The 5' untranslated region of hepatitis C virus (HCV) genomic RNA contains an internal ribosome entry site (IRES) element, composed of domains II-IV, which is required for cap-independent translation initiation. Little information on the 3D structure of the whole functional HCV IRES is still available. Here, we use atomic force microscopy to visualize the HCV IRES conformation in its natural sequence context, which includes the upstream domain I and the essential, downstream domains V and VI. The 574 nt-long molecule analyzed underwent an unexpected, Mg(2+)-induced switch between two alternative conformations: from 'open', elongated morphologies at 0-2 mM Mg(2+) concentration to a 'closed', comma-shaped conformation at 4-6 mM Mg(2+). This sharp transition, confirmed by gel-shift analysis and partial RNase T1 cleavage, was hindered by the microRNA miR-122. The comma-shaped IRES-574 molecules visualized at 4-6 mM Mg(2+) in the absence of miR-122 showed two arms. Our data support that the first arm would contain domain III, while the second one would be composed of domains (I-II)+(V-VI) thanks to a long-range RNA interaction between the I-II spacer and the basal region of domain VI. This reinforces the previously described structural continuity between the HCV IRES and its flanking domains I, V and VI.
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Affiliation(s)
- Ana García-Sacristán
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain
| | - Miguel Moreno
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain
| | - Ascensión Ariza-Mateos
- Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina 'López-Neyra' (CSIC), Parque Tecnológico Ciencias de la Salud, Armilla, Granada 18016, Spain
| | - Elena López-Camacho
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid 28049, Spain
| | - Rosa M Jáudenes
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain
| | - Luis Vázquez
- Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid 28049, Spain
| | - Jordi Gómez
- Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain Laboratory of RNA Archaeology, Instituto de Parasitología y Biomedicina 'López-Neyra' (CSIC), Parque Tecnológico Ciencias de la Salud, Armilla, Granada 18016, Spain
| | - José Ángel Martín-Gago
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid 28049, Spain
| | - Carlos Briones
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid 28850, Spain Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Spain
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Sahana S, Bharadwaj PK. Detection of alkali and alkaline earth metal ions by fluorescence spectroscopy. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Zhao L, Liu Y, He C, Wang J, Duan C. Coordination-driven nanosized lanthanide ‘Molecular Lanterns’ as luminescent chemosensors for the selective sensing of magnesium ions. Dalton Trans 2014; 43:335-43. [DOI: 10.1039/c3dt51900g] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Mammalian cells tightly regulate cellular Mg(2+) content through a variety of transport and buffering mechanisms under the control of various hormones and cellular second messengers. The effect of these hormones and agents results in dynamic changes in the total content of Mg(2+) being transported across the cell membrane and redistributed within cellular compartments. The importance of maintaining proper cellular Mg(2+) content optimal for the activity of various cellular enzymes and metabolic cycles is underscored by the evidence that several diseases are characterized by a loss of Mg(2+) within specific tissues as a result of defective transport, hormonal stimulation, or metabolic impairment. This chapter will review the key mechanisms regulating cellular Mg(2+) homeostasis and their impairments under the most common diseases associated with Mg(2+) loss or deficiency.
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Affiliation(s)
- Andrea M P Romani
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4970, USA,
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15
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Selisko B, Potisopon S, Agred R, Priet S, Varlet I, Thillier Y, Sallamand C, Debart F, Vasseur JJ, Canard B. Molecular basis for nucleotide conservation at the ends of the dengue virus genome. PLoS Pathog 2012; 8:e1002912. [PMID: 23028313 PMCID: PMC3441707 DOI: 10.1371/journal.ppat.1002912] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/03/2012] [Indexed: 12/02/2022] Open
Abstract
The dengue virus (DV) is an important human pathogen from the Flavivirus genus, whose genome- and antigenome RNAs start with the strictly conserved sequence pppAG. The RNA-dependent RNA polymerase (RdRp), a product of the NS5 gene, initiates RNA synthesis de novo, i.e., without the use of a pre-existing primer. Very little is known about the mechanism of this de novo initiation and how conservation of the starting adenosine is achieved. The polymerase domain NS5PolDV of NS5, upon initiation on viral RNA templates, synthesizes mainly dinucleotide primers that are then elongated in a processive manner. We show here that NS5PolDV contains a specific priming site for adenosine 5′-triphosphate as the first transcribed nucleotide. Remarkably, in the absence of any RNA template the enzyme is able to selectively synthesize the dinucleotide pppAG when Mn2+ is present as catalytic ion. The T794 to A799 priming loop is essential for initiation and provides at least part of the ATP-specific priming site. The H798 loop residue is of central importance for the ATP-specific initiation step. In addition to ATP selection, NS5PolDV ensures the conservation of the 5′-adenosine by strongly discriminating against viral templates containing an erroneous 3′-end nucleotide in the presence of Mg2+. In the presence of Mn2+, NS5PolDV is remarkably able to generate and elongate the correct pppAG primer on these erroneous templates. This can be regarded as a genomic/antigenomic RNA end repair mechanism. These conservational mechanisms, mediated by the polymerase alone, may extend to other RNA virus families having RdRps initiating RNA synthesis de novo. The 5′- and 3′-ends of RNA virus genomes have evolved towards efficient replication, translation, and escape from defense mechanisms of the host cell. Little is known about how RNA viruses conserve or restore the correct ends of their genomes. The Flavivirus genus of positive-strand RNA viruses contains important human pathogens such as yellow fever virus, West Nile virus, Japanese encephalitis virus and dengue virus (DV). The Flavivirus genome ends are strictly conserved as 5′-AG…CU-3′. We demonstrate here the primary role of the DV polymerase in the conservation of the first and last genomic residue. We show that DV polymerase contains an ATP-specific priming site, which imposes a strong preference for the de novo synthesis of a dinucleotide primer starting with an ATP. Furthermore, the polymerase is able to indirectly correct erroneous sequences by producing the correct primer in the absence of template and on templates containing incorrect nucleotides at the 3′-end. The correct primer is productively elongated on either correct or incorrect templates. Our findings provide a direct demonstration of the implication of a viral RNA polymerase in the conservation and repair of genome ends. Other polymerases from other RNA virus families are likely to employ similar mechanisms.
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Affiliation(s)
- Barbara Selisko
- Aix-Marseille Université, CNRS, AFMB UMR 7257, 163, Marseille, France.
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Aliverdieva D, Mamaev D, Snezhkova L, Sholtz C. Evaluation of molecularity of rate-limiting step of pore formation by antimicrobial peptides studied using mitochondria as a biosensor. Toxicol In Vitro 2012; 26:939-49. [DOI: 10.1016/j.tiv.2012.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 03/09/2012] [Accepted: 04/05/2012] [Indexed: 10/28/2022]
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17
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Romani AMP. Cellular magnesium homeostasis. Arch Biochem Biophys 2011; 512:1-23. [PMID: 21640700 PMCID: PMC3133480 DOI: 10.1016/j.abb.2011.05.010] [Citation(s) in RCA: 354] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 12/12/2022]
Abstract
Magnesium, the second most abundant cellular cation after potassium, is essential to regulate numerous cellular functions and enzymes, including ion channels, metabolic cycles, and signaling pathways, as attested by more than 1000 entries in the literature. Despite significant recent progress, however, our understanding of how cells regulate Mg(2+) homeostasis and transport still remains incomplete. For example, the occurrence of major fluxes of Mg(2+) in either direction across the plasma membrane of mammalian cells following metabolic or hormonal stimuli has been extensively documented. Yet, the mechanisms ultimately responsible for magnesium extrusion across the cell membrane have not been cloned. Even less is known about the regulation in cellular organelles. The present review is aimed at providing the reader with a comprehensive and up-to-date understanding of the mechanisms enacted by eukaryotic cells to regulate cellular Mg(2+) homeostasis and how these mechanisms are altered under specific pathological conditions.
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Affiliation(s)
- Andrea M P Romani
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA.
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18
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Dalal P, Romani A. Adenosine triphosphate depletion by cyanide results in a Na(+)-dependent Mg(2+) extrusion from liver cells. Metabolism 2010; 59:1663-71. [PMID: 20494376 PMCID: PMC2928872 DOI: 10.1016/j.metabol.2010.03.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 03/08/2010] [Accepted: 03/29/2010] [Indexed: 10/19/2022]
Abstract
Addition of NaCN to isolated hepatocytes results in a marked and rapid decrease in cellular adenosine triphosphate (ATP) content, and in the extrusion of a sizable amount of cellular Mg(2+). This extrusion starts after a 10-minute lag phase and reaches a maximum of 35 to 40 nmol Mg(2+) per milligram protein within 60 minutes from the addition of CN(-). A quantitatively similar Mg(2+) extrusion is also observed after the addition of the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxy-phenylhydrazone but not that of the glycolysis inhibitor iodoacetate. The Mg(2+) extrusion is completely inhibited by the removal of extracellular Na(+) or the addition of imipramine, quinidine, or glibenclamide, whereas it persists after the removal of extracellular Ca(2+) or K(+), or the addition of amiloride. An acidic extracellular pH or the removal of extracellular HCO₃⁻ inhibits the cyanide-induced Mg(2+) extrusion by at least 80%. Taken together, these data suggest that the decrease in cellular adenosine triphosphate content removes a major Mg(2+) complexing agent from the hepatocyte and results in an extrusion of hepatic Mg(2+) exclusively through a Na(+)-dependent exchange mechanism modulated by acidic changes in extracellular pH.
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Affiliation(s)
| | - Andrea Romani
- To whom correspondence should be addressed: Dr. Andrea Romani, Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA, Phone : 216 3681625, Fax: 216-3683952,
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Huang CY, Liou YF, Chung SY, Pai PY, Kan CB, Kuo CH, Tsai CH, Tsai FJ, Chen JL, Lin JY. Increased expression of glucose transporter 3 in gerbil brains following magnesium sulfate treatment and focal cerebral ischemic injury. Cell Biochem Funct 2010; 28:313-20. [PMID: 20517896 DOI: 10.1002/cbf.1659] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Glucose is the primary energy substrate for neurons. Glucose transporter 3 (Glut3) localizes at the neuronal cellular membrane, which transports glucose from the extracelluar space into neurons. Ischemia results in an increased energy demand that is associated with profound changes in brain energy metabolism. Magnesium sulfate (MgSO(4)) ameliorates ischemia-induced neuronal death in the rat and gerbil model. We investigated the effects of MgSO(4) administration on the expression of Glut3 in cortex and hippocampus of gerbils during ischemia. The focal cerebral ischemia was produced by unilateral occlusion of the right common carotid artery and right middle cerebral artery. Following ischemia, Glut3 expression increased significantly versus non-ischemic (contra-lateral) cortex and hippocampus. MgSO(4) treatment significantly increased the level of Glut3 expression in the non-ischemic and ischemic cortex and hippocampus. We found that the MgSO(4)-induced increase in Glut3 expression was not reversed by administration of U0126, a MEK kinase inhibitor. These results suggest that other factors may function to modulate the MgSO(4)-induced Glut3 response. In all, our data showed that MgSO(4) increases the expression of Glut3 in the cortex and hippocampus of gerbil brains both in non-ischemia and ischemia status. However, the MEK signaling pathway might not be involved in MgSO(4)-induced Glut3 expression following focal ischemia.
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Affiliation(s)
- Chih-Yang Huang
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan
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Young A, Berti-Mattera L, Romani A. Effect of Repeated Doses of Ethanol on Hepatic Mg2+Homeostasis and Mobilization. Alcohol Clin Exp Res 2007; 31:1240-51. [PMID: 17577394 DOI: 10.1111/j.1530-0277.2007.00408.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The acute administration of a first dose of ethanol (EtOH) to rat liver cells reduces the amount of Mg(2+) extruded by a second dose of EtOH or the subsequent addition of adrenergic agonists. In contrast, the Mg(2+) extrusion normally elicited by the alpha(1)-adrenergic or beta-adrenergic agonist does not impair the Mg(2+) mobilization induced by the subsequent addition of EtOH. Inhibition of EtOH metabolism by 4-methylpyrazole abolishes almost completely the Mg(2+) extrusion induced by the first dose of EtOH, and partially enlarges that elicited by the second dose of alcohol or the subsequent adrenergic stimulation. Ethanol-treated liver cells stimulated by the adrenergic agonist show a reduced level of membrane-bound Galphas as well as a reduced cellular cAMP content. Analysis of cellular Mg(2+) distribution indicates that EtOH administration decreases the Mg(2+) content of the cytoplasm, mitochondria, and endoplasmic reticulum to a comparable extent. These data indicate that acute EtOH administration directly impairs cellular Mg(2+) homeostasis and also prevents a further Mg(2+) mobilization by additional doses of alcohol or alpha(1)-adrenoceptor and beta-adrenoceptor agonist by decreasing cytosolic and intraorganelle Mg(2+) content and by affecting G-protein membrane distribution/signaling.
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MESH Headings
- Adrenergic Agonists/pharmacology
- Animals
- Dose-Response Relationship, Drug
- Ethanol/pharmacokinetics
- Fomepizole
- GTP-Binding Proteins/drug effects
- GTP-Binding Proteins/metabolism
- GTP-Binding Proteins/physiology
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Homeostasis/drug effects
- Humans
- Liver/chemistry
- Liver/drug effects
- Liver/metabolism
- Liver Diseases, Alcoholic/etiology
- Liver Diseases, Alcoholic/metabolism
- Magnesium/analysis
- Magnesium/metabolism
- Male
- Pyrazoles/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/physiology
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/physiology
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- Andrew Young
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4970, USA
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21
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Romani A. Regulation of magnesium homeostasis and transport in mammalian cells. Arch Biochem Biophys 2006; 458:90-102. [PMID: 16949548 DOI: 10.1016/j.abb.2006.07.012] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 07/21/2006] [Indexed: 02/06/2023]
Abstract
Magnesium is the second most abundant cation within the cell after potassium and plays an important role in numerous biological functions. Several pieces of experimental evidence indicate that mammalian cells tightly regulate Mg(2+) content by precise control mechanisms operating at the level of Mg(2+) entry and efflux across the cell membrane, as well as at the level of intracellular Mg(2+) buffering and organelle compartmentation under resting conditions and following hormonal stimuli. This review will attempt to elucidate the mechanisms involved in hormonal-mediated Mg(2+) extrusion and accumulation, as well as the physiological implications of changes in cellular Mg(2+) content following hormonal stimuli.
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Affiliation(s)
- Andrea Romani
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA.
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22
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Torres LM, Youngner J, Romani A. Role of glucose in modulating Mg2+ homeostasis in liver cells from starved rats. Am J Physiol Gastrointest Liver Physiol 2005; 288:G195-206. [PMID: 15647605 DOI: 10.1152/ajpgi.00488.2003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Alpha1- and beta-adrenoceptor stimulation elicits Mg2+ extrusion from liver cells in conjunction with hepatic glucose output (T. Fagan and A. Romani. Am J Physiol Gastrointest Liver Physiol 279: G943-G950, 2000.). To characterize the role of intrahepatic glucose on Mg2+ transport, male Sprague-Dawley rats were starved overnight before being anesthetized and used as organ donors. Perfused livers or collagenase-dispersed hepatocytes were stimulated by alpha1 (phenylephrine)- or beta (isoproterenol)-adrenergic agonists. Mg2+ extrusion was assessed by atomic absorbance spectrophotometry. In both experimental models, the administration of pharmacological doses of adrenergic agonists did not elicit Mg2+ extrusion. The determination of cellular Mg2+ indicated an approximately 9% decrease in total hepatic Mg2+ content in liver cells after overnight fasting, whereas the ATP level was unchanged. Hepatocytes from starved rats accumulated approximately four times more Mg2+ than liver cells from fed animals. This enlarged Mg2+ accumulation depended in part on extracellular glucose, since it was markedly reduced in the absence of extracellular glucose or in the presence of the glucose transport inhibitor phloretin. The residual Mg2+ accumulation observed in the absence of extracellular glucose was completely abolished by imipramine or removal of extracellular Na+. Taken together, these data indicate 1) that hepatic glucose mobilization is essential for Mg2+ extrusion by adrenergic agonist and 2) that starved hepatocytes accumulate Mg2+ via two distinct pathways, one of which is associated with glucose transport, whereas the second can be tentatively identified as an imipramine-inhibited Na+-dependent pathway.
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Affiliation(s)
- Lisa M Torres
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-4970, USA
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23
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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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Young A, Cefaratti C, Romani A. Chronic EtOH administration alters liver Mg2+ homeostasis. Am J Physiol Gastrointest Liver Physiol 2003; 284:G57-67. [PMID: 12488234 DOI: 10.1152/ajpgi.00153.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ethanol (EtOH) administration to rats for 4 wk markedly decreased Mg(2+) content in several tissues, including liver. Total cellular Mg(2+) accounted for 26.8 +/- 2.4 vs. 36.0 +/- 1.4 nmol Mg(2+)/mg protein in hepatocytes from EtOH-fed and control rats, respectively, and paralleled a 13% decrease in cellular ATP content. Stimulation of alpha(1)- or beta-adrenergic receptor or acute EtOH administration did not elicit an extrusion of Mg(2+) from liver cells of EtOH-fed rats while releasing 5% of total tissue Mg(2+) content from hepatocytes of control rats. Despite the 25% decrease in Mg(2+) content, hepatocytes from EtOH-fed rats did not accumulate Mg(2+) following stimulation of protein kinase C signaling pathway, whereas control hepatocytes accumulated approximately 2 nmol Mg(2+). mg protein(-1). 4 min(-1). Together, these data indicate that Mg(2+) homeostasis and transport are markedly impaired in liver cells after prolonged exposure to alcohol. The inability of liver cells, and possibly other tissues, to accumulate Mg(2+) can help explain the reduction in tissue Mg(2+) content following chronic alcohol consumption.
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Affiliation(s)
- Andrew Young
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970, USA
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25
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Suzuki Y, Komatsu H, Ikeda T, Saito N, Araki S, Citterio D, Hisamoto D, Kitamura Y, Kubota T, Nakagawa J, Oka K, Suzuki K. Design and synthesis of Mg2+-selective fluoroionophores based on a coumarin derivative and application for Mg2+ measurement in a living cell. Anal Chem 2002; 74:1423-8. [PMID: 11922313 DOI: 10.1021/ac010914j] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Novel Mg2+ fluorescent molecular probes (KMG-20-AM and KMG-27-AM; where AM is an acetoxymethyl group) based on a coumarin possessing a charged beta-diketone structure were designed and synthesized. These fluorescent probes produced a red shift from 425 to 445 nm in the absorption spectra after formation of a complex with Mg2+. The fluorescence spectra of these probes also showed a red shift from 485 to 495 nm and an increasing fluorescence intensity after formation of a complex with Mg2+. The optimum experimental conditions were excitation wavelength of 445 nm and a monitored wavelength of 500 nm, where these probes functioned as an indicator showing an image of increasing fluorescence in the presence of Mg2+. These probes showed a "seesaw-type" fluorescent spectral change with the isosbestic point at 480 nm due to the light excitation at 445 nm, which indicates that ratiometry can be used for the measurement. The molecular probes formed a 1:1 complex with Mg2+ and the dissociation constant (Kd) was 10.0 mM for KMG-20. The association constants of the probes with Mg2- were approximately 3 times higher than that with Ca2+, which showed that the selectivity of Mg2+ versus Ca2+ for these probes was over 200 times higher than that for commercially available Mg2+ fluorescent molecular probes such as mag-fura-2, Magnesium Green. As an application of these probes, intracellular fluorescent imaging of Mg2+ was demonstrated using a fluorescent microscope. After the addition of KMG-20-AM and KMG-27-AM into PC12 cells, a strong fluorescence was observed in the cytoplasm and a weak fluorescence in the nuclei region. After treatment with a high-K+ medium, the fluorescence intensity increased due to increasing intracellular Mg2+. The real image of Mg2+ release from the magnesium store was successfully observed with these Mg2+ fluorescent probes.
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Affiliation(s)
- Yoshio Suzuki
- Collaboration of Regional Entities for the Advancement of Technological Excellence, Kanagawa Academy of Science and Technology, Kawasaki, Japan
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Abstract
We have devised a general synthesis of Mg(2+) indicators which is based on the aminophenol triacetic acid (APTRA) structure. The key step is a palladium-catalyzed coupling reaction of a precursor of the APTRA ligand with a fluorescent group. This strategy resulted in new ratioable fluorescent APTRA indicators and the finding that the fluorescence response of these indicators is different for Mg(2+) and Ca(2+) in some cases. We believe that this represents a generally useful approach for combining fluorophore and chelator functionalities.
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Affiliation(s)
- P A Otten
- National Institute of Environmental Health Sciences, Laboratory of Structural Biology, P.O. Box 12233, MR-01, Research Triangle Park, North Carolina 27709, USA
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27
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Abstract
Although the general pathways of glycogen synthesis and glycogenolysis are identical in all tissues, the enzymes involved are uniquely adapted to the specific role of glycogen in different cell types. In liver, where glycogen is stored as a reserve of glucose for extrahepatic tissues, the glycogen-metabolizing enzymes have properties that enable the liver to act as a sensor of blood glucose and to store or mobilize glycogen according to the peripheral needs. The prime effector of hepatic glycogen deposition is glucose, which blocks glycogenolysis and promotes glycogen synthesis in various ways. Other glycogenic stimuli for the liver are insulin, glucocorticoids, parasympathetic (vagus) nerve impulses and gluconeogenic precursors such as fructose and amino acids. The phosphorolysis of glycogen is mainly mediated by glucagon and by the orthosympathetic neurotransmitters noradrenaline and ATP. Many glycogenolytic stimuli, e.g. adenosine, nucleotides and NO, also act indirectly, via secretion of eicosanoids from non-parenchymal cells. Effectors often initiate glycogenolysis cooperatively through different mechanisms.
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Affiliation(s)
- M Bollen
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
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