1
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Masuelli S, Real S, McMillen P, Oudin M, Levin M, Roqué M. The Yin and Yang of Breast Cancer: Ion Channels as Determinants of Left-Right Functional Differences. Int J Mol Sci 2023; 24:11121. [PMID: 37446299 PMCID: PMC10342022 DOI: 10.3390/ijms241311121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/17/2023] [Accepted: 06/23/2023] [Indexed: 07/15/2023] Open
Abstract
Breast cancer is a complex and heterogeneous disease that displays diverse molecular subtypes and clinical outcomes. Although it is known that the location of tumors can affect their biological behavior, the underlying mechanisms are not fully understood. In our previous study, we found a differential methylation profile and membrane potential between left (L)- and right (R)-sided breast tumors. In this current study, we aimed to identify the ion channels responsible for this phenomenon and determine any associated phenotypic features. To achieve this, experiments were conducted in mammary tumors in mice, human patient samples, and with data from public datasets. The results revealed that L-sided tumors have a more depolarized state than R-sided. We identified a 6-ion channel-gene signature (CACNA1C, CACNA2D2, CACNB2, KCNJ11, SCN3A, and SCN3B) associated with the side: L-tumors exhibit lower expression levels than R-tumors. Additionally, in silico analyses show that the signature correlates inversely with DNA methylation writers and with key biological processes involved in cancer progression, such as proliferation and stemness. The signature also correlates inversely with patient survival rates. In an in vivo mouse model, we confirmed that KI67 and CD44 markers were increased in L-sided tumors and a similar tendency for KI67 was found in patient L-tumors. Overall, this study provides new insights into the potential impact of anatomical location on breast cancer biology and highlights the need for further investigation into possible differential treatment options.
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Affiliation(s)
- Sofía Masuelli
- Institute of Histology and Embryology, National Council of Scientific and Technological Research (CONICET), Parque General San Martin, Mendoza 5500, Argentina; (S.M.)
- Faculty of Medical Science, National University of Cuyo, Parque General San Martin, Mendoza 5500, Argentina
| | - Sebastián Real
- Institute of Histology and Embryology, National Council of Scientific and Technological Research (CONICET), Parque General San Martin, Mendoza 5500, Argentina; (S.M.)
- Faculty of Medical Science, National University of Cuyo, Parque General San Martin, Mendoza 5500, Argentina
| | - Patrick McMillen
- Allen Discovery Center, Tufts University, Medford, MA 02155, USA
| | - Madeleine Oudin
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Michael Levin
- Allen Discovery Center, Tufts University, Medford, MA 02155, USA
| | - María Roqué
- Institute of Histology and Embryology, National Council of Scientific and Technological Research (CONICET), Parque General San Martin, Mendoza 5500, Argentina; (S.M.)
- Faculty of Exact and Natural Sciences, National University of Cuyo, Parque General San Martin, Mendoza 5500, Argentina
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2
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Wagner M, Blum D, Raschka SL, Nentwig LM, Gertzen CGW, Chen M, Gatsogiannis C, Harris A, Smits SHJ, Wagner R, Schmitt L. A New Twist in ABC Transporter Mediated Multidrug Resistance - Pdr5 is a Drug/proton Co-transporter. J Mol Biol 2022; 434:167669. [PMID: 35671830 DOI: 10.1016/j.jmb.2022.167669] [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: 12/22/2021] [Revised: 06/01/2022] [Accepted: 06/01/2022] [Indexed: 10/18/2022]
Abstract
The two major efflux pump systems that are involved in multidrug resistance (MDR) are (i) ATP binding cassette (ABC) transporters and (ii) secondary transporters. While the former use binding and hydrolysis of ATP to facilitate export of cytotoxic compounds, the latter utilize electrochemical gradients to expel their substrates. Pdr5 from Saccharomyces cerevisiae is a prominent member of eukaryotic ATP binding cassette (ABC) transporters that are involved in multidrug resistance (MDR) and used as a frequently studied model system. Although investigated for decades, the underlying molecular mechanisms of drug transport and substrate specificity remain elusive. Here, we provide electrophysiological data on the reconstituted Pdr5 demonstrating that this MDR efflux pump does not only actively translocate its substrates across the lipid bilayer, but at the same time generates a proton motif force in the presence of Mg2+-ATP and substrates by acting as a proton/drug co-transporter. Importantly, a strictly substrate dependent co-transport of protons was also observed in in vitro transport studies using Pdr5-enriched plasma membranes. We conclude from these results that the mechanism of MDR conferred by Pdr5 and likely other transporters is more complex than the sole extrusion of cytotoxic compounds and involves secondary coupled processes suitable to increase the effectiveness.
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Affiliation(s)
- Manuel Wagner
- Institute of Biochemistry, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Daniel Blum
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany
| | - Stefanie L Raschka
- Institute of Biochemistry, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Lea-Marie Nentwig
- Institute of Biochemistry, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Christoph G W Gertzen
- Center for Structural Studies Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany; Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Minghao Chen
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms Universität Münster, 48149 Münster, Germany; Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms Universität Münster, 48149 Münster, Germany; Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Andrzej Harris
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany; Center for Structural Studies Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Richard Wagner
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany.
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany.
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3
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Brkovic N, Zhang L, Peters JN, Kleine-Doepke S, Parak WJ, Zhu D. Quantitative Assessment of Endosomal Escape of Various Endocytosed Polymer-Encapsulated Molecular Cargos upon Photothermal Heating. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2003639. [PMID: 33108047 DOI: 10.1002/smll.202003639] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Encapsulated molecular cargos are efficiently endocytosed by cells. For cytosolic delivery, understanding the dynamic process of cargos release from the carrier vehicles used for encapsulation and the lysosomes where the carrier vehicles are trapped (which in general is the bottleneck), followed by diffusion in the cytosol is important for improving drug/gene delivery strategies. A methodology is reported to image this process on a millisecond scale and to quantitatively analyze the data. Polyelectrolyte capsules with embedded gold nanostars to encapsulate 43 fluorescent molecular cargos with diverse properties, ranging from small fluorophores to fluorescently labeled proteins, siRNA, etc., are used. By short laser irradiation intracellular release of the molecular cargos from endocytosed capsules into the cytosol is triggered, and their intracellular spreading is imaged. Most of the released molecular cargos evenly distribute inside the entire cell, while others are enriched in certain cell compartments. The time the different molecular cargos take to distribute within cells, i.e., the spreading time, is used as a quantifier. Quantitative analysis reveals that intracellular spread cannot be described by free diffusion, but is determined by interaction of the molecular cargo with intracellular components.
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Affiliation(s)
- Nico Brkovic
- Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universitat Hamburg, Hamburg, 20146, Germany
| | - Li Zhang
- Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universitat Hamburg, Hamburg, 20146, Germany
| | - Jan N Peters
- Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universitat Hamburg, Hamburg, 20146, Germany
| | - Stephan Kleine-Doepke
- Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universitat Hamburg, Hamburg, 20146, Germany
| | - Wolfgang J Parak
- Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universitat Hamburg, Hamburg, 20146, Germany
| | - Dingcheng Zhu
- Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universitat Hamburg, Hamburg, 20146, Germany
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4
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Geissinger SE, Schreiber A, Huber MC, Stühn LG, Schiller SM. Adjustable Bioorthogonal Conjugation Platform for Protein Studies in Live Cells Based on Artificial Compartments. ACS Synth Biol 2020; 9:827-842. [PMID: 32130855 DOI: 10.1021/acssynbio.9b00494] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The investigation of complex biological processes in vivo often requires defined multiple bioconjugation and positioning of functional entities on 3D structures. Prominent examples include spatially defined protein complexes in nature, facilitating efficient biocatalysis of multistep reactions. Mimicking natural strategies, synthetic scaffolds should comprise bioorthogonal conjugation reactions and allow for absolute stoichiometric quantification as well as facile scalability through scaffold reproduction. Existing in vivo scaffolding strategies often lack covalent conjugations on geometrically confined scaffolds or precise quantitative characterization. Addressing these shortcomings, we present a bioorthogonal dual conjugation platform based on genetically encoded artificial compartments in vivo, comprising two distinct genetically encoded covalent conjugation reactions and their precise stoichiometric quantification. The SpyTag/SpyCatcher (ST/SC) bioconjugation and the controllable strain-promoted azide-alkyne cycloaddition (SPAAC) were implemented on self-assembled protein membrane-based compartments (PMBCs). The SPAAC reaction yield was quantified to be 23% ± 3% and a ST/SC surface conjugation yield of 82% ± 9% was observed, while verifying the compatibility of both chemical reactions as well as enhanced proteolytic stability. Using tandem mass spectrometry, absolute concentrations of the proteinaceous reactants were calculated to be 0.11 ± 0.05 attomol/cell for PMBC surface-tethered mCherry-ST-His and 0.22 ± 0.09 attomol/cell for PMBC-constituting pAzF-SC-E20F20-His. The established in vivo conjugation platform enables quantifiable protein-protein interaction studies on geometrically defined scaffolds and paves the road to investigate effects of scaffold-tethering on enzyme activity.
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Affiliation(s)
- Süreyya E. Geissinger
- Zentrum für Biosystemanalyse (ZBSA), University of Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Andreas Schreiber
- Zentrum für Biosystemanalyse (ZBSA), University of Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Matthias C. Huber
- Zentrum für Biosystemanalyse (ZBSA), University of Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Lara G. Stühn
- Zentrum für Biosystemanalyse (ZBSA), University of Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Stefan M. Schiller
- Zentrum für Biosystemanalyse (ZBSA), University of Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Albertstraße 19, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestraße 18, 79104, Freiburg, Germany
- Cluster of Excellence livMatS @ FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
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5
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Audi SH, Cammarata A, Clough AV, Dash RK, Jacobs ER. Quantification of mitochondrial membrane potential in the isolated rat lung using rhodamine 6G. J Appl Physiol (1985) 2020; 128:892-906. [PMID: 32134711 DOI: 10.1152/japplphysiol.00789.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial membrane potential (Δψm) plays a key role in vital mitochondrial functions, and its dissipation is a hallmark of mitochondrial dysfunction. The objective of this study was to develop an experimental and computational approach for estimating Δψm in intact rat lungs using the lipophilic fluorescent cationic dye rhodamine 6G (R6G). Rat lungs were excised and connected to a ventilation-perfusion system. The experimental protocol consisted of three single-pass phases, loading, washing, and uncoupling, in which the lungs were perfused with R6G-containing perfusate, fresh R6G-free perfusate, or R6G-free perfusate containing the mitochondrial uncoupler FCCP, respectively. This protocol was carried out with lung perfusate containing verapamil vehicle or verapamil, an inhibitor of the multidrug efflux pump P-glycoprotein (Pgp). Results show that the addition of FCCP resulted in an increase in R6G venous effluent concentration and that this increase was larger in the presence of verapamil than in its absence. A physiologically based pharmacokinetic (PBPK) model for the pulmonary disposition of R6G was developed and used for quantitative interpretation of the kinetic data, including estimating Δψm. The estimated value of Δψm [-144 ± 24 (SD) mV] was not significantly altered by inhibiting Pgp with verapamil and is comparable with that estimated previously in cultured pulmonary endothelial cells. These results demonstrate the utility of the proposed approach for quantifying Δψm in intact functioning lungs. This approach has potential to provide quantitative assessment of the effect of injurious conditions on lung mitochondrial function and to evaluate the impact of therapies that target mitochondria.NEW & NOTEWORTHY A novel experimental and computational approach for estimating mitochondrial membrane potential (Δψm) in intact functioning lungs is presented. The isolated rat lung inlet-outlet concentrations of the fluorescent cationic dye rhodamine 6G were measured and analyzed by using a computational model of its pulmonary disposition to determine Δψm. The approach has the potential to provide quantitative assessment of the effect of injurious conditions and their therapies on lung mitochondrial function.
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Affiliation(s)
- Said H Audi
- Department of Biomedical Engineering, Marquette University-Medical College of Wisconsin, Milwaukee, Wisconsin.,Clement J. Zablocki Department of Veterans Affairs Medical Center, Milwaukee, Wisconsin.,Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Anthony Cammarata
- Department of Biomedical Engineering, Marquette University-Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Anne V Clough
- Clement J. Zablocki Department of Veterans Affairs Medical Center, Milwaukee, Wisconsin.,Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Mathematical and Statistical Sciences, Marquette University, Milwaukee, Wisconsin
| | - Ranjan K Dash
- Department of Biomedical Engineering, Marquette University-Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Elizabeth R Jacobs
- Clement J. Zablocki Department of Veterans Affairs Medical Center, Milwaukee, Wisconsin.,Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
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6
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Khan S, Naseem I. A comparative insight into the oxidative damage and cell death potential of photoilluminated aminophylline - riboflavin system in normal and cancer lung cells of swiss albino mice. Toxicol In Vitro 2019; 61:104651. [PMID: 31526835 DOI: 10.1016/j.tiv.2019.104651] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/06/2019] [Accepted: 09/11/2019] [Indexed: 02/03/2023]
Abstract
Photosensitisation of riboflavin (Rf) activates aminophylline (Am) resulting into the formation of a highly pro-oxidant Am-Rf system. We have previously shown its macromolecular damaging response in human peripheral lymphocytes, however, its potential inside a cancer cell is yet to be explored. Since, altered redox status of a cancer cell is a reliable therapeutic window in designing anticancer strategies, therefore, it's imperative to investigate whether the reactive oxygen species (ROS) generated by this system readily triggers apoptosis or it is countered by elevated antioxidant machinery of a cancer cell. Here, we have demonstrated DNA damaging and cytotoxic potential of this system in benzopyrene induced lung carcinoma cells. Using various biochemical assays significant macromolecular damage was observed along with mitochondrial membrane disruption as evaluated by rhodamine 6G membrane permeant. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed decreased cell viability, confirming cytotoxic action whereas fluorescence and electron microscopic evaluation confirmed apoptosis. ROS scavengers ameliorated the oxidative damage and inhibited cell death, thus confirming, pivotal role of ROS in causing cell death. It was evidently found out that the lung cancer cells were more sensitive towards the photodynamic action of this system, which can be attributed to the upregulated riboflavin metabolism in cancer cell. Hence, we propose a photodynamic mechanism to kill lung cancer cell that exhibits enhanced sensitivity towards cancer cells.
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Affiliation(s)
- Saniyya Khan
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, UP 202002, India.
| | - Imrana Naseem
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, UP 202002, India.
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7
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Tuszynski J, Tilli TM, Levin M. Ion Channel and Neurotransmitter Modulators as Electroceutical Approaches to the Control of Cancer. Curr Pharm Des 2019; 23:4827-4841. [PMID: 28554310 PMCID: PMC6340161 DOI: 10.2174/1381612823666170530105837] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 05/17/2017] [Accepted: 05/23/2017] [Indexed: 11/22/2022]
Abstract
The activities of individual cells must be tightly coordinated in order to build and maintain complex 3-dimensional body structures during embryogenesis and regeneration. Thus, one way to view cancer is within systems biology as a network disorder affecting the ability of cells to properly interact with a morphodynamic field of instructive signals that keeps proliferation and migration orchestrated toward the anatomical needs of the host or-ganism. One layer of this set of instructive microenvironmental cues is bioelectrical. Voltage gradients among all somatic cells (not just excitable nerve and muscle) control cell behavior, and the ionic coupling of cells into networks via electrochemical synapses allows them to implement tissue-level patterning decisions. These gradients have been increasingly impli-cated in the induction and suppression of tumorigenesis and metastasis, in the emerging links between developmental bioelectricity to the cancer problem. Consistent with the well-known role of neurotransmitter molecules in transducing electrical activity to downstream cascades in the brain, serotonergic signaling has likewise been implicated in cancer. Here, we review these recent data and propose new approaches for manipulating bioelectric and neurotransmitter pathways in cancer biology based on a bioelectric view of cancer. To sup-port this methodology, we present new data on the effects of the SSRI Prozac and its analog (ZINC ID = ZINC06811610) on survival of both cancer (MCF7) and normal (MCF10A) breast cells exposed to these compounds. We found an IC50 concentration (25 μM for Pro-zac and 100 μM for the Prozac analog) at which these compounds inhibited tumor cell sur-vival and proliferation. Additionally, at these concentrations, we did not observe alterations in a non-tumoral cell line. This constitutes a proof-of-concept demonstration for our hy-pothesis that the use of both existing and novel drugs as electroceuticals could serve as an alternative to highly toxic chemotherapy strategies replacing or augmenting them with less toxic alternatives. We believe this new approach forms an exciting roadmap for future bio-medical advances.
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Affiliation(s)
- Jack Tuszynski
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta. Canada
| | - Tatiana M Tilli
- Laboratory of Biological System Modeling, National Institute for Science and Technology on Innovation in Neglected Diseases (INCT/IDN), Center for Technological Development in Health (CDTS), Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro. Brazil
| | - Michael Levin
- Biology Department, and Allen Discovery Center, Tufts University, Medford, MA, 02155. United States
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8
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Bartolowits M, Xin M, Petrov DP, Tague TJ, Davisson VJ. Multimeric Rhodamine Dye-Induced Aggregation of Silver Nanoparticles for Surface-Enhanced Raman Scattering. ACS OMEGA 2019; 4:140-145. [PMID: 30729221 PMCID: PMC6356857 DOI: 10.1021/acsomega.8b02970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 12/18/2018] [Indexed: 05/17/2023]
Abstract
Isotopic variants of Rhodamine 6G (R6G) have previously been used as a method of multiplexed detection for Surface Enhanced Raman Spectroscopy (SERS), including protein detection and quantification. Challenges exist, however, with producing long-term stable SERS signals with exposure to silver or gold metal surfaces without the use of additional protective coatings of nanomaterials. Here, novel rhodamine "dimers" and "trimers" have been created that demonstrate a higher avidity for metal nanoparticles and induce aggregation to create plasmonic "hotspots" as indicated by enhanced Raman scattering in situ. These aggregates can be formed in a colloid, on surfaces, or membrane substrates such as poly(vinylidene fluoride) for applications in biosciences. The integrity of the materials and Raman signals are maintained for months of time on different substrates. These dye materials should provide avenues for simplified in situ generation of sensors for Raman-based assays especially in settings requiring highly robust performance.
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Affiliation(s)
- Matthew
D. Bartolowits
- Amplified
Sciences, LLC, 1281 Win
Hentschel Blvd., West Lafayette, Indiana 47906, United
States
| | - Meiguo Xin
- Department
of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dino P. Petrov
- Department
of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States
| | - Thomas J. Tague
- Bruker
Optics, Inc., 19 Fortune Drive, Billerica, Massachusetts 01821, United States
| | - Vincent Jo Davisson
- Department
of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States
- E-mail:
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Hernández‐Reséndiz I, Gallardo‐Pérez JC, López‐Macay A, Robledo‐Cadena DX, García‐Villa E, Gariglio P, Saavedra E, Moreno‐Sánchez R, Rodríguez‐Enríquez S. Mutant p53
R248Q
downregulates oxidative phosphorylation and upregulates glycolysis under normoxia and hypoxia in human cervix cancer cells. J Cell Physiol 2018; 234:5524-5536. [DOI: 10.1002/jcp.27354] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 08/17/2018] [Indexed: 01/13/2023]
Affiliation(s)
| | | | - Ambar López‐Macay
- Laboratorio de Enfermedades Neuromusculares Instituto Nacional de Rehabilitación Ciudad de México México
| | | | - Enrique García‐Villa
- Laboratorio de Biología y Genética Molecular Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional‐Zacatenco Ciudad de México México
| | - Patricio Gariglio
- Laboratorio de Biología y Genética Molecular Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional‐Zacatenco Ciudad de México México
| | - Emma Saavedra
- Departamento de Bioquímica Instituto Nacional de Cardiología Ciudad de México México
| | - Rafael Moreno‐Sánchez
- Departamento de Bioquímica Instituto Nacional de Cardiología Ciudad de México México
| | - Sara Rodríguez‐Enríquez
- Departamento de Bioquímica Instituto Nacional de Cardiología Ciudad de México México
- Laboratorio de Medicina Translacional Instituto Nacional de Cancerología Ciudad de México México
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10
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Dual regulation of energy metabolism by p53 in human cervix and breast cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3266-78. [PMID: 26434996 DOI: 10.1016/j.bbamcr.2015.09.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/25/2015] [Accepted: 09/30/2015] [Indexed: 12/14/2022]
Abstract
The role of p53 as modulator of OxPhos and glycolysis was analyzed in HeLa-L (cells containing negligible p53 protein levels) and HeLa-H (p53-overexpressing) human cervix cancer cells under normoxia and hypoxia. In normoxia, functional p53, mitochondrial enzyme contents, mitochondrial electrical potential (ΔΨm) and OxPhos flux increased in HeLa-H vs. HeLa-L cells; whereas their glycolytic enzyme contents and glycolysis flux were unchanged. OxPhos provided more than 70% of the cellular ATP and proliferation was abolished by anti-mitochondrial drugs in HeLa-H cells. In hypoxia, both cell proliferations were suppressed, but HeLa-H cells exhibited a significant decrease in OxPhos protein contents, ΔΨm and OxPhos flux. Although glycolytic function was also diminished vs. HeLa-L cells in hypoxia, glycolysis provided more than 60% of cellular ATP in HeLa-H cells. The energy metabolism phenotype of HeLa-H cells was reverted to that of HeLa-L cells by incubating with pifithrin-α, a p53-inhibitor. In normoxia, the energy metabolism phenotype of breast cancer MCF-7 cells was similar to that of HeLa-H cells, whereas p53shRNAMCF-7 cells resembled the HeLa-L cell phenotype. In hypoxia, autophagy proteins and lysosomes contents increased 2-5 times in HeLa-H cells suggesting mitophagy activation. These results indicated that under normoxia p53 up-regulated OxPhos without affecting glycolysis, whereas under hypoxia, p53 down-regulated both OxPhos (severely) and glycolysis (weakly). These p53 effects appeared mediated by the formation of p53-HIF-1α complexes. Therefore, p53 exerts a dual and contrasting regulatory role on cancer energy metabolism, depending on the O₂level.
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11
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Fedoseeva M, Letrun R, Vauthey E. Excited-State Dynamics of Rhodamine 6G in Aqueous Solution and at the Dodecane/Water Interface. J Phys Chem B 2014; 118:5184-93. [DOI: 10.1021/jp502058e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Marina Fedoseeva
- Department
of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, Geneva, Switzerland
| | - Romain Letrun
- Department
of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, Geneva, Switzerland
| | - Eric Vauthey
- Department
of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, Geneva, Switzerland
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12
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A study on the system of nonaqueous microchip electrophoresis with on-line peroxyoxalate chemiluminescence detection. J Sep Sci 2013; 36:713-20. [DOI: 10.1002/jssc.201200832] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 10/24/2012] [Accepted: 10/24/2012] [Indexed: 01/16/2023]
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13
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Rodríguez-Enríquez S, Hernández-Esquivel L, Marín-Hernández A, Dong LF, Akporiaye ET, Neuzil J, Ralph SJ, Moreno-Sánchez R. Molecular mechanism for the selective impairment of cancer mitochondrial function by a mitochondrially targeted vitamin E analogue. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1597-607. [PMID: 22627082 DOI: 10.1016/j.bbabio.2012.05.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/30/2012] [Accepted: 05/10/2012] [Indexed: 12/31/2022]
Abstract
The effects of α-tocopheryl succinate (α-TOS), α-tocopheryl acetyl ether (α-TEA) and triphenylphosphonium-tagged vitamin E succinate (mitochondrially targeted vitamin E succinate; MitoVES) on energy-related mitochondrial functions were determined in mitochondria isolated from AS-30D hepatoma and rat liver, bovine heart sub-mitochondrial particles (SMPs), and in rodent and human carcinoma cell lines and rat hepatocytes. In isolated mitochondria, MitoVES stimulated basal respiration and ATP hydrolysis, but inhibited net state 3 (ADP-stimulated) respiration and Ca(2+) uptake, by collapsing the membrane potential at low doses (1-10μM). Uncoupled mitochondrial respiration and basal respiration of SMPs were inhibited by the three drugs at concentrations at least one order of magnitude higher and with different efficacy: MitoVES>α-TEA>α-TOS. At high doses (>10μM), the respiratory complex II (CII) was the most sensitive MitoVES target. Acting as an uncoupler at low doses, this agent stimulated total O(2) uptake, collapsed ∆ψ(m), inhibited oxidative phosphorylation and induced ATP depletion in rodent and human cancer cells more potently than in normal rat hepatocytes. These findings revealed that in situ tumor mitochondria are preferred targets of the drug, indicating its clinical relevance.
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Gerencser AA, Chinopoulos C, Birket MJ, Jastroch M, Vitelli C, Nicholls DG, Brand MD. Quantitative measurement of mitochondrial membrane potential in cultured cells: calcium-induced de- and hyperpolarization of neuronal mitochondria. J Physiol 2012; 590:2845-71. [PMID: 22495585 DOI: 10.1113/jphysiol.2012.228387] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial membrane potential (ΔΨM) is a central intermediate in oxidative energy metabolism. Although ΔΨM is routinely measured qualitatively or semi-quantitatively using fluorescent probes, its quantitative assay in intact cells has been limited mostly to slow, bulk-scale radioisotope distribution methods. Here we derive and verify a biophysical model of fluorescent potentiometric probe compartmentation and dynamics using a bis-oxonol-type indicator of plasma membrane potential (ΔΨP) and the ΔΨM probe tetramethylrhodamine methyl ester (TMRM) using fluorescence imaging and voltage clamp. Using this model we introduce a purely fluorescence-based quantitative assay to measure absolute values of ΔΨM in millivolts as they vary in time in individual cells in monolayer culture. The ΔΨP-dependent distribution of the probes is modelled by Eyring rate theory. Solutions of the model are used to deconvolute ΔΨP and ΔΨM in time from the probe fluorescence intensities, taking into account their slow, ΔΨP-dependent redistribution and Nernstian behaviour. The calibration accounts for matrix:cell volume ratio, high- and low-affinity binding, activity coefficients, background fluorescence and optical dilution, allowing comparisons of potentials in cells or cell types differing in these properties. In cultured rat cortical neurons, ΔΨM is −139 mV at rest, and is regulated between −108 mV and −158 mV by concerted increases in ATP demand and Ca2+-dependent metabolic activation. Sensitivity analysis showed that the standard error of the mean in the absolute calibrated values of resting ΔΨM including all biological and systematic measurement errors introduced by the calibration parameters is less than 11 mV. Between samples treated in different ways, the typical equivalent error is ∼5 mV.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA.
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15
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Quantitative analysis of molecular absorption into PDMS microfluidic channels. Ann Biomed Eng 2012; 40:1862-73. [PMID: 22484830 DOI: 10.1007/s10439-012-0562-z] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 03/27/2012] [Indexed: 01/07/2023]
Abstract
Microfluidic devices fabricated using poly(dimethylsiloxane) (PDMS) polymer are routinely used for in vitro cell culture for a wide range of cellular assays. These assays typically involve the incubation of cultured cells with a drug molecule or a fluorescent marker while monitoring a cellular response. The accuracy of these assays depends on achieving a consistent and reproducible concentration of solute molecules in solution. However, hydrophobic therapeutic and fluorescent molecules tend to diffuse into the PDMS walls of the microfluidic devices, which reduce their concentration in solution and consequently affect the accuracy and reliability of these assays. In this paper, we quantitatively investigate the relationship between the partition coefficient (log P) of a series of markers routinely used in in vitro cellular assays including [3H]-dexamethasone, [3H]-diazepam, [14C]-mannitol, [3H]-phenytoin, and rhodamine 6G and their absorption into PDMS microfluidic channels. Our results show that the absorption of a given solute into PDMS depends on the hydrophilic/hydrophobic balance defined by its log P value. Specifically, results demonstrate that molecules with log P less than 2.47 exhibit minimal absorption (<10%) into PDMS channels whereas molecules with log P larger than 2.62 exhibit extensive absorption (>90%) into PDMS channels. Further investigations showed that TiO(2) and glass coatings of PDMS channels reduced the absorption of hydrophobic molecules (log P > 2.62) by 2- and 4.5-folds, respectively.
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Shavit E, Michaelson DM, Chapman J. Anatomical localization of protease-activated receptor-1 and protease-mediated neuroglial crosstalk on peri-synaptic astrocytic endfeet. J Neurochem 2011; 119:460-73. [PMID: 21854391 DOI: 10.1111/j.1471-4159.2011.07436.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We studied the localization, activation and function of protease-activated receptor 1 (PAR-1) at the CNS synapse utilizing rat brain synaptosomes and slices. Confocal immunofluoresence and transmission electron microscopy in brain slices with pre-embedding diaminobenzidine (DAB) immunostaining found PAR-1 predominantly localized to the peri-synaptic astrocytic endfeet. Structural confocal immunofluorescence microscopy studies of isolated synaptosomes revealed spherical structures stained with anti-PAR-1 antibody which co-stained mainly for glial-filament acidic protein compared with the neuronal markers synaptophysin and PSD-95. Immunoblot studies of synaptosomes demonstrated an appropriate major band corresponding to PAR-1 and activation of the receptor by a specific agonist peptide (SFLLRN) significantly modulated phosphorylated extracellular signal-regulated kinase. A significant membrane potential depolarization was produced by thrombin (1 U/mL) and the PAR-1 agonist (100 μM) and depolarization by high K(+) elevated extracellular thrombin-like activity in the synaptosomes preparation. The results indicate PAR-1 localized to the peri-synaptic astrocytic endfeet is most likely activated by synaptic proteases and induces cellular signaling and modulation of synaptic electrophysiology. A protease mediated neuron-glia pathway may be important in both physiological and pathological regulation of the synapse.
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Affiliation(s)
- Efrat Shavit
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel
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Gan Z, Audi SH, Bongard RD, Gauthier KM, Merker MP. Quantifying mitochondrial and plasma membrane potentials in intact pulmonary arterial endothelial cells based on extracellular disposition of rhodamine dyes. Am J Physiol Lung Cell Mol Physiol 2011; 300:L762-72. [PMID: 21239539 DOI: 10.1152/ajplung.00334.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Our goal was to quantify mitochondrial and plasma potential (Δψ(m) and Δψ(p)) based on the disposition of rhodamine 123 (R123) or tetramethylrhodamine ethyl ester (TMRE) in the medium surrounding pulmonary endothelial cells. Dyes were added to the medium, and their concentrations in extracellular medium ([R(e)]) were measured over time. R123 [R(e)] fell from 10 nM to 6.6 ± 0.1 (SE) nM over 120 min. TMRE [R(e)] fell from 20 nM to a steady state of 4.9 ± 0.4 nM after ∼30 min. Protonophore or high K(+) concentration ([K(+)]), used to manipulate contributions of membrane potentials, attenuated decreases in [R(e)], and P-glycoprotein (Pgp) inhibition had the opposite effect, demonstrating the qualitative impact of these processes on [R(e)]. A kinetic model incorporating a modified Goldman-Hodgkin-Katz model was fit to [R(e)] vs. time data for R123 and TMRE, respectively, under various conditions to obtain (means ± 95% confidence intervals) Δψ(m) (-130 ± 7 and -133 ± 4 mV), Δψ(p) (-36 ± 4 and -49 ± 4 mV), and a Pgp activity parameter (K(Pgp), 25 ± 5 and 51 ± 11 μl/min). The higher membrane permeability of TMRE also allowed application of steady-state analysis to obtain Δψ(m) (-124 ± 6 mV). The consistency of kinetic parameter values obtained from R123 and TMRE data demonstrates the utility of this experimental and theoretical approach for quantifying intact cell Δψ(m) and Δψ(p.) Finally, steady-state analysis revealed that although room air- and hyperoxia-exposed (95% O(2) for 48 h) cells have equivalent resting Δψ(m), hyperoxic cell Δψ(m) was more sensitive to depolarization with protonophore, consistent with previous observations of pulmonary endothelial hyperoxia-induced mitochondrial dysfunction.
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Affiliation(s)
- Zhuohui Gan
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
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18
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19
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Klapperstück T, Glanz D, Klapperstück M, Wohlrab J. Methodological aspects of measuring absolute values of membrane potential in human cells by flow cytometry. Cytometry A 2009; 75:593-608. [PMID: 19504578 DOI: 10.1002/cyto.a.20735] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The bis-barbituric acid oxonol, DiBAC(4)(3) is used as a standard potentiometric probe in human cells. However, its fluorescence depends not only on membrane potential but also varies with nonpotential related changes in the amount of intracellular free and bound dye. This study demonstrates the influence of different experimental conditions on this nonspecific fluorescence proportion. IGR1 melanoma cells as a model were specifically altered in cell volume and protein content by depolarizing treatments or cell cycle synchronization. Flow cytometry was performed over a wide range of extracellular DiBAC(4)(3) concentrations. Fixation and increase in protein content led to a nonspecifically enhanced fluorescence, while changes in the amount of free intracellular dye as a result of altered cell volume proved to be negligible. To establish a calibration curve using totally depolarized cells, the pore-forming action of gramicidin should be preferred to fixation. Below 100 nM DiBAC(4)(3), the logarithmic relation between cell fluorescence and dye concentration turned into a virtually linear function intersecting with zero. Consequently, calibration can then be confined to determination of the fluorescence of depolarized cells stained with the same concentration as used for the actual measurement of membrane potential. Unexpectedly, quenching of fluorescence occurred in totally depolarized cells at concentrations higher than 6,250 nM. Linearity and quenching could be confirmed by additional experiments on Chinese hamster ovary CHO-K1 and B lymphoblastoid LCL-HO cells.
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Affiliation(s)
- Thomas Klapperstück
- Department of Dermatology and Venereology, Martin Luther University of Halle-Wittenberg, Saale, Germany.
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20
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21
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Luisi R, Panza E, Barrese V, Iannotti FA, Viggiano D, Secondo A, Canzoniero LMT, Martire M, Annunziato L, Taglialatela M. Activation of pre-synaptic M-type K+ channels inhibits [3H]D-aspartate release by reducing Ca2+ entry through P/Q-type voltage-gated Ca2+ channels. J Neurochem 2009; 109:168-81. [PMID: 19187447 DOI: 10.1111/j.1471-4159.2009.05945.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, the functional consequences of the pharmacological modulation of the M-current (I(KM)) on cytoplasmic Ca(2+) intracellular Ca(2+)concentration ([Ca(2+)](i)) changes and excitatory neurotransmitter release triggered by various stimuli from isolated rat cortical synaptosomes have been investigated. K(v)7.2 immunoreactivity was identified in pre-synaptic elements in cortical slices and isolated glutamatergic cortical synaptosomes. In cerebrocortical synaptosomes exposed to 20 mM [K(+)](e), the I(KM) activator retigabine (RT, 10 microM) inhibited [(3)H]D-aspartate ([(3)H]D-Asp) release and caused membrane hyperpolarization; both these effects were prevented by the I(KM) blocker XE-991 (20 microM). The I(KM) activators RT (0.1-30 microM), flupirtine (10 microM) and BMS-204352 (10 microM) inhibited 20 mM [K(+)](e)-induced synaptosomal [Ca(2+)](i) increases; XE-991 (20 microM) abolished RT-induced inhibition of depolarization-triggered [Ca(2+)](i) transients. The P/Q-type voltage-sensitive Ca(2+)channel (VSCC) blocker omega-agatoxin IVA prevented RT-induced inhibition of depolarization-induced [Ca(2+)](i) increase and [(3)H]D-Asp release, whereas the N-type blocker omega-conotoxin GVIA failed to do so. Finally, 10 microM RT did not modify the increase of [Ca(2+)](i) and the resulting enhancement of [(3)H]D-Asp release induced by [Ca(2+)](i) mobilization from intracellular stores, or by store-operated Ca(2+)channel activation. Collectively, the present data reveal that the pharmacological activation of I(KM) regulates depolarization-induced [(3)H]D-Asp release from cerebrocortical synaptosomes by selectively controlling the changes of [Ca(2+)](i) occurring through P/Q-type VSCCs.
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Affiliation(s)
- Rosa Luisi
- Department of Neuroscience, Division of Pharmacology, University of Naples Federico II, Naples, Italy
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22
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Duan Y, Nicholson RA. 20(S)-protopanaxadiol and the ginsenoside Rh2 inhibit Na+ channel-activated depolarization and Na+ channel-dependent amino acid neurotransmitter release in synaptic fractions isolated from mammalian brain. Comp Biochem Physiol C Toxicol Pharmacol 2008; 147:351-6. [PMID: 18262850 DOI: 10.1016/j.cbpc.2008.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/17/2007] [Accepted: 01/03/2008] [Indexed: 11/29/2022]
Abstract
The ginsenoside Rh(2) and its aglycone 20(S)-protopanaxadiol are known to inhibit the binding of [(3)H]batrachotoxinin 20alpha-benzoate to site 2 on voltage-gated sodium channels and electrophysiological investigations conducted by others have shown that ginsenosides cause voltage-dependent inhibition of reconstituted forms of the sodium channel. Here we describe the actions of Rh(2) and 20(S)-protopanaxadiol on sodium channel function and release of neurotransmitters resulting from activation of native sodium channels in synaptic preparations isolated from whole mouse brain. Rh(2) and 20(S)-protopanaxadiol inhibited veratridine-dependent (tetrodotoxin-suppressible) depolarization of synaptoneurosomes as determined using the rhodamine 6G method although 20(S)-protopanaxadiol was more potent as an inhibitor than Rh(2). Veratridine- (sodium channel-) dependent release of the neurotransmitters L-glutamate and GABA was almost fully inhibited by 20(S)-protopanaxadiol, however, less complete inhibition was observed with Rh(2). At its maximum inhibitory concentration, Rh(2) also produced release of l-glutamate and GABA from synaptosomes, in contrast to 20(S)-protopanaxadiol. We conclude that low to moderate micromolar concentrations of Rh(2) and 20(S)-protopanaxadiol inhibit sodium channel function and sodium channel-activated release of neurotransmitters. Apparently the ginsenoside Rh(2) cannot achieve complete inhibition of sodium channel-activated transmitter release because at high concentrations it also stimulates release.
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Affiliation(s)
- Yin Duan
- Department of Biological Sciences, Simon Fraser University, 8888, University Drive, Burnaby, British Columbia, Canada V5A 1S6
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23
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Duan Y, Zheng J, Nicholson RA. Inhibition of [3H]batrachotoxinin A-20alpha-benzoate binding to sodium channels and sodium channel function by endocannabinoids. Neurochem Int 2007; 52:438-46. [PMID: 17888543 DOI: 10.1016/j.neuint.2007.08.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 07/24/2007] [Accepted: 08/09/2007] [Indexed: 11/18/2022]
Abstract
A number of putative endocannabinoids were found to modify the binding of [(3)H]batrachotoxinin A-20alpha-benzoate ([(3)H]BTX-B) to site 2 on voltage-gated sodium channels of mouse brain and achieve functional inhibition of sodium channels in vitro. 2-Arachidonoyl-glycerol (2-AG), arachidonoyl glycerol ether (AGE), N-arachidonoyl-dopamine (NADA) gave almost complete inhibition of [(3)H]BTX-B binding with IC(50) values of 90.4, 51.2 and 20.7 microM, respectively. The CB1 receptor antagonist AM251 (2 microM) had no effect on the displacement of radioligand by these endocanabinoids. Arachidonoyl-glycine (A-Gly) and arachidonoyl-GABA (A-GABA) were apparently less effective inhibitors of [(3)H]BTX-B binding giving 14.8+/-2.2 and 23.9+/-4.8% inhibition at 100 microM. Phenylmethanesulphonylfluoride (PMSF) did not alter the inhibitory effects of 2-AG, AGE, NADA and A-Gly on binding, but the efficacy of 100 microM A-GABA was increased by 60.3+/-6.3% (P<0.05). Scatchard analyses showed that 2-AG, AGE and NADA reduce the binding of [(3)H]BTX-B by lowering B(max) although increases in K(D) were also evident for AGE and NADA. Our kinetic experiments found that 2-AG, AGE and NADA increase the dissociation velocity of radioligand from site 2 on sodium channels demonstrating that these endocannabinoids operate as allosteric inhibitors of [(3)H]BTX-B binding. 2-AG, AGE and NADA inhibited veratridine-dependent (TTX-suppressible) depolarization of the plasma membrane of synaptoneurosomes at low micromolar concentrations and again the capacities of A-Gly and A-GABA to inhibit this response were less pronounced. The three most effective endocannabinoids (2-AG, AGE and NADA) were then examined in a synaptosomal transmitter release assay where they were observed to inhibit sodium channel- (veratridine-dependent) release of l-glutamate and GABA in the low micromolar range. These effects also occurred through a mechanism that was not influenced by 2 microM AM251. It is concluded that direct inhibition of sodium channel function leading to reduced neuronal excitation and depression of presynaptic release of amino acid transmitters is a property shared by several endocannabinoids.
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Affiliation(s)
- Yin Duan
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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Tarasenko AS, Storchak LG, Himmelreich NH. alpha-Latrotoxin affects mitochondrial potential and synaptic vesicle proton gradient of nerve terminals. Neurochem Int 2007; 52:392-400. [PMID: 17728017 DOI: 10.1016/j.neuint.2007.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 07/06/2007] [Accepted: 07/17/2007] [Indexed: 11/29/2022]
Abstract
Ca(2+)-independent [(3)H]GABA release induced by alpha-latrotoxin was found to consist of two sequential processes: a fast initial release realized via exocytosis and more delayed outflow through the plasma membrane GABA transporters [Linetska, M.V., Storchak, L.G., Tarasenko, A.S., Himmelreich, N.H., 2004. Involvement of membrane GABA transporters in alpha-latrotoxin-stimulated [(3)H]GABA release. Neurochem. Int. 44, 303-312]. To characterize the toxin-stimulated events attributable to the transporter-mediated [(3)H]GABA release from rat brain synaptosomes we studied the effect of alpha-latrotoxin on membrane potentials and generation of the synaptic vesicles proton gradient, using fluorescent dyes: potential-sensitive rhodamine 6G and pH-sensitive acridine orange. We revealed that alpha-latrotoxin induced a progressive dose-dependent depolarization of mitochondrial membrane potential and an irreversible run-down of the synaptic vesicle proton gradient. Both processes were insensitive to the presence of cadmium, a potent blocker of toxin-formed transmembrane pores, indicating that alpha-latrotoxin-induced disturbance of the plasma membrane permeability was not responsible to these effects. A gradual dissipation of the synaptic vesicle proton gradient closely coupled with lowering the vesicular GABA transporter activity results in a leakage of the neurotransmitter from synaptic vesicles to cytoplasm. As a consequence, there is an essential increase in GABA concentration in a soluble cytosolic pool that appears to be critical parameter for altering the mode of the plasma membrane GABA transporter operation from inward to outward. Thus, our data allow clarifying what cell processes underlain a recruitment of the plasma membrane transporter-mediated pathway in alpha-LTX-stimulated secretion.
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Affiliation(s)
- A S Tarasenko
- Department of Neurochemistry, Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Leontovich Str. 9, Kiev 01601, Ukraine
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Abstract
CAD (Cath.a-differentiated) cells, a mouse neuronal cell line, were subjected to electrohydrodynamic jetting at a field strength of 0.47-0.67 kV/mm, corresponding to an applied voltage of 7-10 kV. After jetting, the cells appeared normal and continued to divide at rates similar to those shown by control samples. Jetted cells, when placed in serum-free medium, underwent differentiation that was sustained for at least 1 month. Some of the droplets produced by jetting contained only a few cells. These results indicate that the process of jetting does not significantly perturb neuronal cells and that this novel approach might in the future be a useful way to deposit small numbers of living nerve cells on to surfaces.
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Affiliation(s)
- Peter A M Eagles
- Kings College London, University of London, Randall Division of Cell and Molecular Biophysics, New Hunt's House, St. Thomas Street, London SE1 1UL, UK.
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Pullela PK, Chiku T, Carvan MJ, Sem DS. Fluorescence-based detection of thiols in vitro and in vivo using dithiol probes. Anal Biochem 2006; 352:265-73. [PMID: 16527239 DOI: 10.1016/j.ab.2006.01.047] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 01/24/2006] [Accepted: 01/27/2006] [Indexed: 10/25/2022]
Abstract
Thiols play a central role in maintaining biological homeostasis. Their levels can change dramatically in response to oxidative stress associated with toxic insults, bacterial infection, and disease. Therefore, a reagent that can monitor thiol levels both in vitro and in vivo would be useful for assays and as a biomarker. Such a reagent should (i) be selective for thiols, (ii) be able to penetrate cell walls, and (iii) have a low reduction potential so as not to create oxidative stress in a cell. We have developed such a fluorescent reagent (DSSA) based on a dithiol linker: (i) the use of a dithiol linker makes it selective for thiols; (ii) the use of fluorophores that populate neutral states at physiological pH improves cell wall penetration; and (iii) because of the reagent's low reduction potential (-0.60 V), it will not stress cells oxidatively. For example, 5 microM of reagent is responsive to changes in glutathione levels in the physiologically relevant range of 1 to 10mM, yet this would oxidize less than 1% of cellular glutathione. In Escherichia coli, decreased thiol levels were detected in cells deficient in glutathione synthesis. In zebrafish embryos, the DSSA reagent permitted detection of unusually high thiol levels in the zebrafish chorion.
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Affiliation(s)
- Phani Kumar Pullela
- Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201, USA
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Mandalà M, Brekke JF, Serck-Hanssen G, Metz-Boutigue MH, Helle KB. Chromogranin A-derived peptides: interaction with the rat posterior cerebral artery. ACTA ACUST UNITED AC 2005; 124:73-80. [PMID: 15544843 DOI: 10.1016/j.regpep.2004.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2004] [Revised: 06/05/2004] [Accepted: 07/01/2004] [Indexed: 11/26/2022]
Abstract
Chromogranin A (CgA), an acidic granule protein of the regulated secretory pathway in the diffuse neuroendocrine system, is postulated to serve as a prohormone for regulatory peptides. Betagranin (rCgA(1-128)), the first N-terminal cleavage product of rat CgA, is 87% homologous to the bovine vasostatin I (bCgA(1-76)), previously shown to be vasoinhibitory in bovine resistance arteries. In this study the vasoactivity of homologous rat and bovine peptides was investigated in the rat posterior cerebral artery. Firstly, we examined the interaction of rhodamine (Rh)-labelled bCgA(7-40) and bCgA(47-70) with elements of the arterial wall by fluorescence microscopy. Secondly, rCgA(7-57), bCgA(1-40), bCgA(7-40) and bCgA(47-66) (chromofungin) were studied for effects on arterial tone and intracellular calcium as function of pressure in an arteriograph. Although without dilator or constrictor responses at 60-150 mm Hg, the rat peptide (rCgA(7-57)) evoked a significant delay in the onset of forced dilatation at 170 mm Hg, in contrast to the bovine peptides bCgA(1-40), bCgA(7-40) and bCgA(47-66) (chromofungin). Neither Rh-bCgA(7-40) nor Rh-bCgA(47-70) stained the endothelial layer, while Rh-bCgA(47-70) but not Rh-bCgA(7-40) stained the smooth muscle compartment. Analogously, bCgA(47-66) but not bCgA(7-40) reduced intracellular calcium, however without modifying the myogenic response. Thus, the betagranin peptide rCgA(7-57) and the two bovine chromofungin-containing peptides, highly homologous to the corresponding sequence (rCgA(47-66)), affected the rat cerebral artery without vasodilator effects, indicating significant species differences in vasoactivity of the N-terminal domain of CgA.
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Affiliation(s)
- Maurizio Mandalà
- Department of Biomedicine, Division of Physiology, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
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Helle KB. The granin family of uniquely acidic proteins of the diffuse neuroendocrine system: comparative and functional aspects. Biol Rev Camb Philos Soc 2005; 79:769-94. [PMID: 15682870 DOI: 10.1017/s146479310400644x] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The chromogranins A (CgA) and B (CgB) and secretogranin II (SgII) constitute the main members of a family of uniquely acidic secretory proteins in elements of the diffuse neuroendocrine system. These genetically distinct proteins, CgA, CgB, SgII and the less well known secretogranins III-VII are collectively referred to as 'granins' and characterised by numerous pairs of basic amino acids as potential cleavage sites for processing by the co-stored prohormone converting enzymes PC 1/3 and PC2. This review is directed towards comparative and functional aspects of the granins with emphasis on their phylogenetically conserved sequences. Recent developments provide ample evidence of widely different effects and targets for the intact granins and their derived peptides, intracellularly in the directed trafficking of storage components during granule maturation and extracellularly in autocrine, paracrine and endocrine interactions. Most of the effects assigned to the granin derived peptides fit into patterns of direct or indirect inhibitory modulations of major functions. So far, peptides derived from CgA (vasostatins, chromacin, pancreastatin, WE-14, catestatin and parastatin), CgB (secretolytin) and SgII (secretoneurin) are the most likely candidates for granin-derived regulatory peptides, of postulated relevance not only for homeostatic processes, but also for tissue assembly and repair, inflammatory responses and the first line of defence against invading microorganisms.
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Affiliation(s)
- Karen B Helle
- Department of Biomedicine, Division of Physiology, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway.
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Mao C, Kisaalita WS. Determination of resting membrane potential of individual neuroblastoma cells (IMR-32) using a potentiometric dye (TMRM) and confocal microscopy. J Fluoresc 2005; 14:739-43. [PMID: 15649026 DOI: 10.1023/b:jofl.0000047224.41328.f8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The potentiometric dye, Tetramethylrhodamine methyl ester (TMRM) has been extensively used with fluorometry or optical microscopy to evaluate the electric potential across plasma or mitochondrial membranes. We present here a TMRM confocal microscopy-based potential measurement technique. Corrections are introduced to minimize nonspecific dye binding and insensitivity to low background levels. We have used this technique to compare the resting membrane potential of proliferating and differentiated human neuroblastoma cells (IMR-32).
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Affiliation(s)
- Chen Mao
- Cellular Bioengineering Laboratory, Faculty of Engineering, Driftmier Engineering Center, University of Georgia, Athens, Georgia 30602, USA
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Raiteri L, Schmid G, Prestipino S, Raiteri M, Bonanno G. Activation of alpha 6 GABAA receptors on depolarized cerebellar parallel fibers elicits glutamate release through anion channels. Neuropharmacology 2001; 41:943-51. [PMID: 11747899 DOI: 10.1016/s0028-3908(01)00138-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Rat cerebellar synaptosomes labeled with [3H]D-aspartate ([3H]D-ASP) were exposed in superfusion to muscimol. The GABA(A) receptor agonist did not affect [3H]D-ASP basal release or the overflow provoked by 15mM K(+); muscimol potentiated the 35mM K(+)-evoked overflow of [3H]D-ASP or endogenous glutamate. Membrane potential measured by Rhodamine 6G fluorescence was -65mV under resting conditions and -32mV in the presence of 35mM K(+). The membrane potential was not significantly affected by muscimol. The muscimol effect on the K(+)(35mM)-evoked [3H]D-ASP overflow was not inhibited by omitting external Ca(2+) or by entrapping BAPTA to chelate cytosolic Ca(2+). Muscimol lost its ability to release glutamate following superfusion with D-aspartate to deplete cytosolic glutamate by heteroexchange suggesting that GABA(A) receptor activation elicits release of cytosolic glutamate. The non-transportable glutamate carrier blockers dihydrokainate or DL-TBOA did not reduce the muscimol potentiation. This was abolished by the anion channel blockers niflumic acid and NPPB. To conclude, when cerebellar parallel fiber terminals are sufficiently depolarized, activation of alpha6 GABA(A) receptors on these terminals mediates glutamate release in addition to that evoked by depolarization. This extra-release does not occur by exocytosis or transporter reversal but involves the opening of anion channels present on parallel fiber terminals.
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Affiliation(s)
- L Raiteri
- Dipartimento di Medicina Sperimentale, Sezione di Farmacologia e Tossicologia, Università di Genova, Viale Cembrano 4, 16148, Genova, Italy
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Affiliation(s)
- K B Helle
- Department of Physiology, University of Bergen, 5000 Bergen, Norway
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32
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Mandalà M, Stridsberg M, Helle KB, Serck-Hanssen G. Endothelial handling of chromogranin A. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2001; 482:167-78. [PMID: 11192578 DOI: 10.1007/0-306-46837-9_13] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- M Mandalà
- Department of Physiology, University of Bergen, 5009 Bergen, Norway
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