1
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Gui R, Jin H. Organic fluorophores-based molecular probes with dual-fluorescence ratiometric responses to in-vitro/in-vivo pH for biosensing, bioimaging and biotherapeutics applications. Talanta 2024; 275:126171. [PMID: 38703479 DOI: 10.1016/j.talanta.2024.126171] [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: 01/31/2024] [Revised: 04/19/2024] [Accepted: 04/25/2024] [Indexed: 05/06/2024]
Abstract
In recent years, organic fluorophores-based molecular probes with dual-fluorescence ratiometric responses to in-vitro/in-vivo pH (DFR-MPs-pH) have been attracting much interest in fundamental application research fields. More and more scientific publications have reported the exploration of various DFR-MPs-pH systems that have unique dual-fluorescence ratiometry as the signal output, in-built and signal self-calibration functions to improve precise detection of targets. DFR-MPs-pH systems possess high-performance applications in biosensing, bioimaging and biomedicine fields. This review has comprehensively summarized recent advances of DFR-MPs-pH for the first time. First of all, the compositions and types of DFR-MPs-pH are introduced by summarizing different organic fluorophores-based molecule systems. Then, construction strategies are analyzed based on specific components, structures, properties and functions of DFR-MPs-pH. Afterward, biosensing and bioimaging applications are discussed in detail, primarily referring to pH sensing and imaging detection at the levels of living cells and small animals. Finally, biomedicine applications are fully summarized, majorly involving bio-toxicity evaluation, bio-distribution, biomedical diagnosis and therapeutics. Meanwhile, the current status, challenges and perspectives are rationally commented after detailed discussions of representative and state-of-the-art studies. Overall, this present review is comprehensive, in-time and in-depth, and can facilitate the following further exploration of new and versatile DFR-MPs-pH systems toward rational design, facile preparation, superior properties, adjustable functions and highly efficient applications in promising fields.
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Affiliation(s)
- Rijun Gui
- College of Chemistry and Chemical Engineering, Intellectual Property Research Institute, Qingdao University, Shandong, 266071, PR China.
| | - Hui Jin
- College of Chemistry and Chemical Engineering, Intellectual Property Research Institute, Qingdao University, Shandong, 266071, PR China
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2
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Li SA, Meng XY, Zhang YJ, Chen CL, Jiao YX, Zhu YQ, Liu PP, Sun W. Progress in pH-Sensitive sensors: essential tools for organelle pH detection, spotlighting mitochondrion and diverse applications. Front Pharmacol 2024; 14:1339518. [PMID: 38269286 PMCID: PMC10806205 DOI: 10.3389/fphar.2023.1339518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024] Open
Abstract
pH-sensitive fluorescent proteins have revolutionized the field of cellular imaging and physiology, offering insight into the dynamic pH changes that underlie fundamental cellular processes. This comprehensive review explores the diverse applications and recent advances in the use of pH-sensitive fluorescent proteins. These remarkable tools enable researchers to visualize and monitor pH variations within subcellular compartments, especially mitochondria, shedding light on organelle-specific pH regulation. They play pivotal roles in visualizing exocytosis and endocytosis events in synaptic transmission, monitoring cell death and apoptosis, and understanding drug effects and disease progression. Recent advancements have led to improved photostability, pH specificity, and subcellular targeting, enhancing their utility. Techniques for multiplexed imaging, three-dimensional visualization, and super-resolution microscopy are expanding the horizon of pH-sensitive protein applications. The future holds promise for their integration into optogenetics and drug discovery. With their ever-evolving capabilities, pH-sensitive fluorescent proteins remain indispensable tools for unravelling cellular dynamics and driving breakthroughs in biological research. This review serves as a comprehensive resource for researchers seeking to harness the potential of pH-sensitive fluorescent proteins.
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Affiliation(s)
- Shu-Ang Li
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiao-Yan Meng
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ying-Jie Zhang
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Cai-Li Chen
- Department of Immunology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yu-Xue Jiao
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yong-Qing Zhu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Pei-Pei Liu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Wei Sun
- Department of Burn and Repair Reconstruction, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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3
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Hu Y, Zhang RQ, Liu SL, Wang ZG. In-situ quantification of lipids in live cells through imaging approaches. Biosens Bioelectron 2023; 240:115649. [PMID: 37678059 DOI: 10.1016/j.bios.2023.115649] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/03/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023]
Abstract
Lipids are important molecules that are widely distributed within the cell, and they play a crucial role in several biological processes such as cell membrane formation, signaling, cell motility and division. Monitoring the spatiotemporal dynamics of cellular lipids in real-time and quantifying their concentrations in situ is crucial since the local concentration of lipids initiates various signaling pathways that regulate cellular processes. In this review, we first introduced the historical background of lipid quantification methods. We then delve into the current state of the art of in situ lipid quantification, including the establishment and utility of fluorescence imaging techniques based on sensors of lipid-binding domains labeled with organic dyes or fluorescent proteins, and Raman and magnetic resonance imaging (MRI) techniques that do not require lipid labeling. Next, we highlighted the biological applications of live-cell lipid quantification techniques in the study of in situ lipid distribution, lipid transformation, and lipid-mediated signaling pathways. Finally, we discussed the technical challenges and prospects for the development of lipid quantification in live cells, with the aim of promoting the development of in situ lipid quantification in live cells, which may have a profound impact on the biological and medical fields.
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Affiliation(s)
- Yusi Hu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry and School of Medicine, Nankai University, Tianjin, 300071, China
| | - Rui-Qiao Zhang
- Qingdao Academy of Agricultural Sciences, Qingdao, 266100, China
| | - Shu-Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry and School of Medicine, Nankai University, Tianjin, 300071, China.
| | - Zhi-Gang Wang
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry and School of Medicine, Nankai University, Tianjin, 300071, China.
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4
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Lyons AC, Mehta S, Zhang J. Fluorescent biosensors illuminate the spatial regulation of cell signaling across scales. Biochem J 2023; 480:1693-1717. [PMID: 37903110 PMCID: PMC10657186 DOI: 10.1042/bcj20220223] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 11/01/2023]
Abstract
As cell signaling research has advanced, it has become clearer that signal transduction has complex spatiotemporal regulation that goes beyond foundational linear transduction models. Several technologies have enabled these discoveries, including fluorescent biosensors designed to report live biochemical signaling events. As genetically encoded and live-cell compatible tools, fluorescent biosensors are well suited to address diverse cell signaling questions across different spatial scales of regulation. In this review, methods of examining spatial signaling regulation and the design of fluorescent biosensors are introduced. Then, recent biosensor developments that illuminate the importance of spatial regulation in cell signaling are highlighted at several scales, including membranes and organelles, molecular assemblies, and cell/tissue heterogeneity. In closing, perspectives on how fluorescent biosensors will continue enhancing cell signaling research are discussed.
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Affiliation(s)
- Anne C. Lyons
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, U.S.A
- Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, U.S.A
| | - Sohum Mehta
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, U.S.A
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, U.S.A
- Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, U.S.A
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, U.S.A
- Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, U.S.A
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5
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Scheele CLGJ, Herrmann D, Yamashita E, Celso CL, Jenne CN, Oktay MH, Entenberg D, Friedl P, Weigert R, Meijboom FLB, Ishii M, Timpson P, van Rheenen J. Multiphoton intravital microscopy of rodents. NATURE REVIEWS. METHODS PRIMERS 2022; 2:89. [PMID: 37621948 PMCID: PMC10449057 DOI: 10.1038/s43586-022-00168-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/12/2022] [Indexed: 08/26/2023]
Abstract
Tissues are heterogeneous with respect to cellular and non-cellular components and in the dynamic interactions between these elements. To study the behaviour and fate of individual cells in these complex tissues, intravital microscopy (IVM) techniques such as multiphoton microscopy have been developed to visualize intact and live tissues at cellular and subcellular resolution. IVM experiments have revealed unique insights into the dynamic interplay between different cell types and their local environment, and how this drives morphogenesis and homeostasis of tissues, inflammation and immune responses, and the development of various diseases. This Primer introduces researchers to IVM technologies, with a focus on multiphoton microscopy of rodents, and discusses challenges, solutions and practical tips on how to perform IVM. To illustrate the unique potential of IVM, several examples of results are highlighted. Finally, we discuss data reproducibility and how to handle big imaging data sets.
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Affiliation(s)
- Colinda L. G. J. Scheele
- Laboratory for Intravital Imaging and Dynamics of Tumor Progression, VIB Center for Cancer Biology, KU Leuven, Leuven, Belgium
- Department of Oncology, KU Leuven, Leuven, Belgium
| | - David Herrmann
- Cancer Ecosystems Program, Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Department, Sydney, New South Wales, Australia
- St. Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Erika Yamashita
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, Osaka, Japan
- WPI-Immunology Frontier Research Center, Osaka University, Osaka, Japan
- Laboratory of Bioimaging and Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan
| | - Cristina Lo Celso
- Department of Life Sciences and Centre for Hematology, Imperial College London, London, UK
- Sir Francis Crick Institute, London, UK
| | - Craig N. Jenne
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Maja H. Oktay
- Department of Pathology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA
- Integrated Imaging Program, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA
| | - David Entenberg
- Department of Pathology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA
- Integrated Imaging Program, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA
| | - Peter Friedl
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, Netherlands
- David H. Koch Center for Applied Genitourinary Cancers, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Franck L. B. Meijboom
- Department of Population Health Sciences, Sustainable Animal Stewardship, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
- Faculty of Humanities, Ethics Institute, Utrecht University, Utrecht, Netherlands
| | - Masaru Ishii
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, Osaka, Japan
- WPI-Immunology Frontier Research Center, Osaka University, Osaka, Japan
- Laboratory of Bioimaging and Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan
| | - Paul Timpson
- Cancer Ecosystems Program, Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Department, Sydney, New South Wales, Australia
- St. Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, New South Wales, Australia
| | - Jacco van Rheenen
- Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, Netherlands
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, Netherlands
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Karsten L, Goett-Zink L, Schmitz J, Hoffrogge R, Grünberger A, Kottke T, Müller KM. Genetically Encoded Ratiometric pH Sensors for the Measurement of Intra- and Extracellular pH and Internalization Rates. BIOSENSORS 2022; 12:bios12050271. [PMID: 35624572 PMCID: PMC9138566 DOI: 10.3390/bios12050271] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022]
Abstract
pH-sensitive fluorescent proteins as genetically encoded pH sensors are promising tools for monitoring intra- and extracellular pH. However, there is a lack of ratiometric pH sensors, which offer a good dynamic range and can be purified and applied extracellularly to investigate uptake. In our study, the bright fluorescent protein CoGFP_V0 was C-terminally fused to the ligand epidermal growth factor (EGF) and retained its dual-excitation and dual-emission properties as a purified protein. The tandem fluorescent variants EGF-CoGFP-mTagBFP2 (pK′ = 6.6) and EGF-CoGFP-mCRISPRed (pK′ = 6.1) revealed high dynamic ranges between pH 4.0 and 7.5. Using live-cell fluorescence microscopy, both pH sensor molecules permitted the conversion of fluorescence intensity ratios to detailed intracellular pH maps, which revealed pH gradients within endocytic vesicles. Additionally, extracellular binding of the pH sensors to cells expressing the EGF receptor (EGFR) enabled the tracking of pH shifts inside cultivation chambers of a microfluidic device. Furthermore, the dual-emission properties of EGF-CoGFP-mCRISPRed upon 488 nm excitation make this pH sensor a valuable tool for ratiometric flow cytometry. This high-throughput method allowed for the determination of internalization rates, which represents a promising kinetic parameter for the in vitro characterization of protein–drug conjugates in cancer therapy.
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Affiliation(s)
- Lennard Karsten
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Lukas Goett-Zink
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Julian Schmitz
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Raimund Hoffrogge
- Cell Culture Technology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Alexander Grünberger
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Tilman Kottke
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Kristian M. Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
- Correspondence:
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7
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Nakamura S, Fu N, Kondo K, Wakabayashi KI, Hisabori T, Sugiura K. A luminescent Nanoluc-GFP fusion protein enables readout of cellular pH in photosynthetic organisms. J Biol Chem 2021; 296:100134. [PMID: 33268379 PMCID: PMC7948502 DOI: 10.1074/jbc.ra120.016847] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 11/26/2020] [Accepted: 12/01/2020] [Indexed: 11/06/2022] Open
Abstract
pH is one of the most critical physiological parameters determining vital cellular activities, such as photosynthetic performance. Fluorescent sensor proteins capable of measuring in situ pH in animal cells have been reported. However, these proteins require an excitation laser for pH measurement that may affect photosynthetic performance and induce autofluorescence from chlorophyll. As a result, it is not possible to measure the intracellular or intraorganelle pH changes in plants. To overcome this problem, we developed a luminescent pH sensor by fusing the luminescent protein Nanoluc to a uniquely designed pH-sensitive GFP variant protein. In this system, an excitation laser is unnecessary because the fused GFP variant reports on the luminescent signal by bioluminescence resonance energy transfer from Nanoluc. The ratio of two luminescent peaks from the sensor protein was approximately linear with respect to pH in the range of 7.0 to 8.5. We designated this sensor protein as "luminescent pH indicator protein" (Luphin). We applied Luphin to the in situ pH measurement of a photosynthetic organism under fluctuating light conditions, allowing us to successfully observe the cytosolic pH changes associated with photosynthetic electron transfer in the cyanobacterium Synechocystis sp. PCC 6803. Detailed analyses of the mechanisms of the observed estimated pH changes in the cytosol in this alga suggested that the photosynthetic electron transfer is suppressed by the reduced plastoquinone pool under light conditions. These results indicate that Luphin may serve as a helpful tool to further illuminate pH-dependent processes throughout the photosynthetic organisms.
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Affiliation(s)
- Shungo Nakamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Nae Fu
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Kumiko Kondo
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Ken-Ichi Wakabayashi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Toru Hisabori
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan.
| | - Kazunori Sugiura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
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8
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Steinegger A, Wolfbeis OS, Borisov SM. Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications. Chem Rev 2020; 120:12357-12489. [PMID: 33147405 PMCID: PMC7705895 DOI: 10.1021/acs.chemrev.0c00451] [Citation(s) in RCA: 174] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Indexed: 12/13/2022]
Abstract
This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.
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Affiliation(s)
- Andreas Steinegger
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Otto S. Wolfbeis
- Institute
of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, D-93040 Regensburg, Germany
| | - Sergey M. Borisov
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
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9
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Liu L, He F, Yu Y, Wang Y. Application of FRET Biosensors in Mechanobiology and Mechanopharmacological Screening. Front Bioeng Biotechnol 2020; 8:595497. [PMID: 33240867 PMCID: PMC7680962 DOI: 10.3389/fbioe.2020.595497] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/19/2020] [Indexed: 12/15/2022] Open
Abstract
Extensive studies have shown that cells can sense and modulate the biomechanical properties of the ECM within their resident microenvironment. Thus, targeting the mechanotransduction signaling pathways provides a promising way for disease intervention. However, how cells perceive these mechanical cues of the microenvironment and transduce them into biochemical signals remains to be answered. Förster or fluorescence resonance energy transfer (FRET) based biosensors are a powerful tool that can be used in live-cell mechanotransduction imaging and mechanopharmacological drug screening. In this review, we will first introduce FRET principle and FRET biosensors, and then, recent advances on the integration of FRET biosensors and mechanobiology in normal and pathophysiological conditions will be discussed. Furthermore, we will summarize the current applications and limitations of FRET biosensors in high-throughput drug screening and the future improvement of FRET biosensors. In summary, FRET biosensors have provided a powerful tool for mechanobiology studies to advance our understanding of how cells and matrices interact, and the mechanopharmacological screening for disease intervention.
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Affiliation(s)
| | | | | | - Yingxiao Wang
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, United States
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10
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Han Y, Yang W, Luo X, He X, Zhao H, Tang W, Yue T, Li Z. Carbon dots based ratiometric fluorescent sensing platform for food safety. Crit Rev Food Sci Nutr 2020; 62:244-260. [PMID: 32876496 DOI: 10.1080/10408398.2020.1814197] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Food safety has become a major global concern and the rapid detection of food nutritional ingredients and contaminants has aroused much more attention. Nanomaterials-based fluorescent sensing holds great potential in designing highly sensitive and selective detection strategies for food safety analysis. Carbon dots (CDs) possess tremendous prospects in fluorescent sensing food ingredients and contaminants due to their superior properties of chemical and photostability, highly fluorescence with tunability, and no/low-toxicity. Numerous endeavors are demanded to contribute to overcoming the challenge of lower sensitivity and selectivity of the sensors interfered by various components in intricate food matrices to ensure food safety and human health. Nanohybrid CDs based ratiometric fluorescent sensing with self-calibration is regarded as an efficient strategy for the CDs based sensors for the specific recognition of target analyte in the food matrices. This work is devoted to reviewing the development of nanohybrid CDs based ratiometric fluorescent sensing platform and the perspectives of the platform for food safety. The applications of nanohybrid CDs in sensing are summarized and the sensing mechanisms are briefly discussed.
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Affiliation(s)
- Yong Han
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China
| | - Weixia Yang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China
| | - Xueli Luo
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China
| | - Xie He
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China
| | - Haiping Zhao
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China
| | - Wenzhi Tang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China
| | - Tianli Yue
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China.,Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, Shaanxi, PR China
| | - Zhonghong Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, PR China.,Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, Shaanxi, PR China
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11
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Rhee KY, Chawla R, Lele PP. Protein expression-independent response of intensity-based pH-sensitive fluorophores in Escherichia coli. PLoS One 2020; 15:e0234849. [PMID: 32555627 PMCID: PMC7302705 DOI: 10.1371/journal.pone.0234849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/02/2020] [Indexed: 12/02/2022] Open
Abstract
Fluorescent proteins that modulate their emission intensities when protonated serve as excellent probes of the cytosolic pH. Since the total fluorescence output fluctuates significantly due to variations in the fluorophore levels in cells, eliminating the dependence of the signal on protein concentration is crucial. This is typically accomplished with the aid of ratiometric fluorescent proteins such as pHluorin. However, pHluorin is excited by blue light, which can complicate pH measurements by adversely impacting bacterial physiology. Here, we characterized the response of intensity-based, pH-sensitive fluorescent proteins that excite at longer wavelengths where the blue light effect is diminished. The pH-response was interpreted in terms of an analytical model that assumed two emission states for each fluorophore: a low intensity protonated state and a high intensity deprotonated state. The model suggested a scaling to eliminate the dependence of the signal on the expression levels as well as on the illumination and photon-detection settings. Experiments successfully confirmed the scaling predictions. Thus, the internal pH can be readily determined with intensity-based fluorophores with appropriate calibrations irrespective of the fluorophore concentration and the signal acquisition setup. The framework developed in this work improves the robustness of intensity-based fluorophores for internal pH measurements in E. coli, potentially extending their applications.
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Affiliation(s)
- Kathy Y. Rhee
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, United States of America
| | - Ravi Chawla
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, United States of America
| | - Pushkar P. Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, United States of America
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12
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Wang L, Zhou Y, Zhang Y, Zhang G, Zhang C, He Y, Dong C, Shuang S. A novel cell-penetrating Janus nanoprobe for ratiometric fluorescence detection of pH in living cells. Talanta 2020; 209:120436. [PMID: 31892062 DOI: 10.1016/j.talanta.2019.120436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/29/2019] [Accepted: 10/03/2019] [Indexed: 12/19/2022]
Abstract
pH regulates the function of many organelles and plays a pivotal role in requiring multitud cellular behaviors. Compared with single fluorescent probes, ratio fluorescent probes have higher sensitivity and immunity to interference. Herein, a novel Janus ratio nanoprobe was developed for intracellular pH detection. Modified rhodamine B probe and fluorescein isothiocyanate (FITC) were individually encapsulated in the independent hemispheres of Janus microparticles fabricated via Pickering emulsion. Moreover, it exhibits a satasified ratiometric detection of pH compared to the previous core-shell structure and organic small molecule probe. Accordingly, the Janus nanoprobe possesses many important features as an attractive sensor, including high anti-jamming capability, excellent stability, good reversibility and low cytotoxicity. Variations of the two fluorescence intensities (Fgreen/Fred) resulted in a ratiometric pH fluorescent sensor, which can respond to wide range of pH values from 3 to 8. To be more specific, with a single excitation wavelength of 488 nm, there are dual emission bands centered at 538 nm and 590 nm. Also the Janus nanoprobe displays a excellent linear relationship in the physiologically relevant pH range of 4.0-6.0. Consequently, detecting of pH and imaging was successfully achieved in living cells, which provides a simple and reliable method for detecting intracelluar pH and other similar substances.
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Affiliation(s)
- Lei Wang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006, China
| | - Ying Zhou
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006, China.
| | - Yan Zhang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006, China
| | - Guomei Zhang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006, China
| | - Caihong Zhang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006, China
| | - Yujian He
- College of Chemistry and Chemical Engineering, University of the Chinese Academy of Sciences, Beijing, 100049, China.
| | - Chuan Dong
- Institute of Environmental Science, Shanxi University, Taiyuan, 030006, China
| | - Shaomin Shuang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, 030006, China.
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13
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Shinoda H, Lu K, Nakashima R, Wazawa T, Noguchi K, Matsuda T, Nagai T. Acid-Tolerant Reversibly Switchable Green Fluorescent Protein for Super-resolution Imaging under Acidic Conditions. Cell Chem Biol 2019; 26:1469-1479.e6. [DOI: 10.1016/j.chembiol.2019.07.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 06/13/2019] [Accepted: 07/23/2019] [Indexed: 02/08/2023]
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14
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Arce‐Rodríguez A, Volke DC, Bense S, Häussler S, Nikel PI. Non-invasive, ratiometric determination of intracellular pH in Pseudomonas species using a novel genetically encoded indicator. Microb Biotechnol 2019; 12:799-813. [PMID: 31162835 PMCID: PMC6559197 DOI: 10.1111/1751-7915.13439] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 11/30/2022] Open
Abstract
The ability of Pseudomonas species to thrive in all major natural environments (i.e. terrestrial, freshwater and marine) is based on its exceptional capability to adapt to physicochemical changes. Thus, environmental bacteria have to tightly control the maintenance of numerous physiological traits across different conditions. The intracellular pH (pHi ) homoeostasis is a particularly important feature, since the pHi influences a large portion of the biochemical processes in the cell. Despite its importance, relatively few reliable, easy-to-implement tools have been designed for quantifying in vivo pHi changes in Gram-negative bacteria with minimal manipulations. Here we describe a convenient, non-invasive protocol for the quantification of the pHi in bacteria, which is based on the ratiometric fluorescent indicator protein PHP (pH indicator for Pseudomonas). The DNA sequence encoding PHP was thoroughly adapted to guarantee optimal transcription and translation of the indicator in Pseudomonas species. Our PHP-based quantification method demonstrated that pHi is tightly regulated over a narrow range of pH values not only in Pseudomonas, but also in other Gram-negative bacterial species such as Escherichia coli. The maintenance of the cytoplasmic pH homoeostasis in vivo could also be observed upon internal (e.g. redirection of glucose consumption pathways in P. putida) and external (e.g. antibiotic exposure in P. aeruginosa) perturbations, and the PHP indicator was also used to follow dynamic changes in the pHi upon external pH shifts. In summary, our work describes a reliable method for measuring pHi in Pseudomonas, allowing for the detailed investigation of bacterial pHi homoeostasis and its regulation.
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Affiliation(s)
- Alejandro Arce‐Rodríguez
- Department of Molecular BacteriologyHelmholtz Centre for Infection Research38124BraunschweigGermany
| | - Daniel C. Volke
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark2800Kongens LyngbyDenmark
| | - Sarina Bense
- Department of Molecular BacteriologyHelmholtz Centre for Infection Research38124BraunschweigGermany
| | - Susanne Häussler
- Department of Molecular BacteriologyHelmholtz Centre for Infection Research38124BraunschweigGermany
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark2800Kongens LyngbyDenmark
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15
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Greenwald EC, Mehta S, Zhang J. Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks. Chem Rev 2018; 118:11707-11794. [PMID: 30550275 DOI: 10.1021/acs.chemrev.8b00333] [Citation(s) in RCA: 295] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.
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Affiliation(s)
- Eric C Greenwald
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Sohum Mehta
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Jin Zhang
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
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16
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Genetically encoded fluorescent indicators for live cell pH imaging. Biochim Biophys Acta Gen Subj 2018; 1862:2924-2939. [PMID: 30279147 DOI: 10.1016/j.bbagen.2018.09.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 02/04/2023]
Abstract
BACKGROUND Intracellular pH underlies most cellular processes. There is emerging evidence of a pH-signaling role in plant cells and microorganisms. Dysregulation of pH is associated with human diseases, such as cancer and Alzheimer's disease. SCOPE OF REVIEW In this review, we attempt to provide a summary of the progress that has been made in the field during the past two decades. First, we present an overview of the current state of the design and applications of fluorescent protein (FP)-based pH indicators. Then, we turn our attention to the development and applications of hybrid pH sensors that combine the capabilities of non-GFP fluorophores with the advantages of genetically encoded tags. Finally, we discuss recent advances in multicolor pH imaging and the applications of genetically encoded pH sensors in multiparameter imaging. MAJOR CONCLUSIONS Genetically encoded pH sensors have proven to be indispensable noninvasive tools for selective targeting to different cellular locations. Although a variety of genetically encoded pH sensors have been designed and applied at the single cell level, there is still much room for improvements and future developments of novel powerful tools for pH imaging. Among the most pressing challenges in this area is the design of brighter redshifted sensors for tissue research and whole animal experiments. GENERAL SIGNIFICANCE The design of precise pH measuring instruments is one of the important goals in cell biochemistry and may give rise to the development of new powerful diagnostic tools for various diseases.
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17
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Soleja N, Manzoor O, Khan I, Ahmad A, Mohsin M. Role of green fluorescent proteins and their variants in development of FRET-based sensors. J Biosci 2018. [DOI: 10.1007/s12038-018-9783-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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18
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Yu H, Chen C, Cao X, Liu Y, Zhou S, Wang P. Ratiometric fluorescent pH nanoprobes based on in situ assembling of fluorescence resonance energy transfer between fluorescent proteins. Anal Bioanal Chem 2017; 409:5073-5080. [PMID: 28687887 DOI: 10.1007/s00216-017-0453-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 05/23/2017] [Accepted: 06/06/2017] [Indexed: 11/25/2022]
Abstract
pH-dependent protein adsorption on mesoporous silica nanoparticle (MSN) was examined as a unique means for pH monitoring. Assuming that the degree of protein adsorption determines the distance separating protein molecules, we examined the feasibility of nanoscale pH probes based on fluorescence resonance energy transfer (FRET) between two fluorescent proteins (mTurquoise2 and mNeonGreen, as donor and acceptor, respectively). Since protein adsorption on MSN is pH-sensitive, both fluorescent proteins were modified to make their isoelectric points (pIs) identical, thus achieving comparable adsorption between the proteins and enhancing FRET signals. The adsorption behaviors of such modified fluorescent proteins were examined along with ratiometric FRET signal generation. Results demonstrated that the pH probes could be manipulated to show feasible sensitivity and selectivity for pH changes in hosting solutions, with a good linearity observed in the pH range of 5.5-8.0. In a demonstration test, the pH probes were successfully applied to monitor progress of enzymatic reactions. Such an "in situ-assembling" pH sensor demonstrates a promising strategy in developing nanoscale fluorescent protein probes. Graphical abstract Working principle of the developed pH sensor TNS; and FRET Ratio (I528/I460) as a function of pH under different protein feed ratios (mNeonGreen to mTurquoise2).
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Affiliation(s)
- Haijun Yu
- State Key Laboratory of Bioreactor Engineering, Biomedical Nanotechnology Center, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Chao Chen
- State Key Laboratory of Bioreactor Engineering, Biomedical Nanotechnology Center, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Xiaodan Cao
- State Key Laboratory of Bioreactor Engineering, Biomedical Nanotechnology Center, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Yueling Liu
- State Key Laboratory of Bioreactor Engineering, Biomedical Nanotechnology Center, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Shengmin Zhou
- State Key Laboratory of Bioreactor Engineering, Biomedical Nanotechnology Center, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China.
| | - Ping Wang
- State Key Laboratory of Bioreactor Engineering, Biomedical Nanotechnology Center, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China.
- Department of Bioproducts and Biosystems Engineering, University of Minnesota, St Paul, MN, 55108, USA.
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19
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Rupprecht C, Wingen M, Potzkei J, Gensch T, Jaeger KE, Drepper T. A novel FbFP-based biosensor toolbox for sensitive in vivo determination of intracellular pH. J Biotechnol 2017; 258:25-32. [PMID: 28501596 DOI: 10.1016/j.jbiotec.2017.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/05/2017] [Accepted: 05/07/2017] [Indexed: 02/07/2023]
Abstract
The intracellular pH is an important modulator of various bio(techno)logical processes such as enzymatic conversion of metabolites or transport across the cell membrane. Changes of intracellular pH due to altered proton distribution can thus cause dysfunction of cellular processes. Consequently, accurate monitoring of intracellular pH allows elucidating the pH-dependency of (patho)physiological and biotechnological processes. In this context, genetically encoded biosensors represent a powerful tool to determine intracellular pH values non-invasively and with high spatiotemporal resolution. We have constructed a toolbox of novel genetically encoded FRET-based pH biosensors (named Fluorescence Biosensors for pH or FluBpH) that utilizes the FMN-binding fluorescent protein EcFbFP as donor domain. In contrast to many fluorescent proteins of the GFP family, EcFbFP exhibits a remarkable tolerance towards acidic pH (pKa∼3.2). To cover the broad range of physiologically relevant pH values, three EYFP variants exhibiting pKa values of 5.7, 6.1 and 7.5 were used as pH-sensing FRET acceptor domains. The resulting biosensors FluBpH 5.7, FluBpH 6.1 and FluBpH 7.5 were calibrated in vitro and in vivo to accurately evaluate their pH indicator properties. To demonstrate the in vivo applicability of FluBpH, changes of intracellular pH were ratiometrically measured in E. coli cells during acid stress.
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Affiliation(s)
- Christian Rupprecht
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Marcus Wingen
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Janko Potzkei
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany; GO-Bio Projekt SenseUP, Forschungszentrum Jülich, D-52425 Jülich GmbH, Germany
| | - Thomas Gensch
- Institute of Complex Systems ICS-4: Cellular Biophysics, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, D-52425 Jülich, Germany; Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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20
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Liu H, Cao X, Wang P, Ma X. pH-sensitive pHluorins as a molecular sensor for in situ
monitoring of enzyme-catalyzed prodrug activation. Biotechnol Appl Biochem 2017; 64:482-489. [DOI: 10.1002/bab.1511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 05/16/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Hui Liu
- Biomedical Nanotechnology Center; State Key Laboratory of Bioreactor Engineering; East China University of Science and Technology; Shanghai People's Republic of China
| | - Xiaodan Cao
- Biomedical Nanotechnology Center; State Key Laboratory of Bioreactor Engineering; East China University of Science and Technology; Shanghai People's Republic of China
| | - Ping Wang
- Biomedical Nanotechnology Center; State Key Laboratory of Bioreactor Engineering; East China University of Science and Technology; Shanghai People's Republic of China
| | - Xingyuan Ma
- Biomedical Nanotechnology Center; State Key Laboratory of Bioreactor Engineering; East China University of Science and Technology; Shanghai People's Republic of China
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21
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Zagaynova EV, Druzhkova IN, Mishina NM, Ignatova NI, Dudenkova VV, Shirmanova MV. Imaging of Intracellular pH in Tumor Spheroids Using Genetically Encoded Sensor SypHer2. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1035:105-119. [DOI: 10.1007/978-3-319-67358-5_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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22
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Zou X, Pan T, Chen L, Tian Y, Zhang W. Luminescence materials for pH and oxygen sensing in microbial cells - structures, optical properties, and biological applications. Crit Rev Biotechnol 2016; 37:723-738. [PMID: 27627832 DOI: 10.1080/07388551.2016.1223011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Luminescence including fluorescence and phosphorescence sensors have been demonstrated to be important for studying cell metabolism, and diagnosing diseases and cancer. Various design principles have been employed for the development of sensors in different formats, such as organic molecules, polymers, polymeric hydrogels, and nanoparticles. The integration of the sensing with fluorescence imaging provides valuable tools for biomedical research and applications at not only bulk-cell level but also at single-cell level. In this article, we critically reviewed recent progresses on pH, oxygen, and dual pH and oxygen sensors specifically for their application in microbial cells. In addition, we focused not only on sensor materials with different chemical structures, but also on design and applications of sensors for better understanding cellular metabolism of microbial cells. Finally, we also provided an outlook for future materials design and key challenges in reaching broad applications in microbial cells.
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Affiliation(s)
- Xianshao Zou
- a Department of Materials Science and Engineering , South University of Science and Technology of China , Shenzhen , Guangdong , P.R. China
| | - Tingting Pan
- a Department of Materials Science and Engineering , South University of Science and Technology of China , Shenzhen , Guangdong , P.R. China
| | - Lei Chen
- b Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology , Tianjin University , Tianjin , P.R. China.,c Key Laboratory of Systems Bioengineering, Ministry of Education of China , Tianjin , P.R. China.,d SynBio Platform, Collaborative Innovation Center of Chemical Science and Engineering , Tianjin , P.R. China
| | - Yanqing Tian
- a Department of Materials Science and Engineering , South University of Science and Technology of China , Shenzhen , Guangdong , P.R. China
| | - Weiwen Zhang
- b Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology , Tianjin University , Tianjin , P.R. China.,c Key Laboratory of Systems Bioengineering, Ministry of Education of China , Tianjin , P.R. China.,d SynBio Platform, Collaborative Innovation Center of Chemical Science and Engineering , Tianjin , P.R. China
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23
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Maulucci G, Chiarpotto M, Papi M, Samengo D, Pani G, De Spirito M. Quantitative analysis of autophagic flux by confocal pH-imaging of autophagic intermediates. Autophagy 2016; 11:1905-16. [PMID: 26506895 PMCID: PMC4824579 DOI: 10.1080/15548627.2015.1084455] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Although numerous techniques have been developed to monitor autophagy and to probe its cellular functions, these methods cannot evaluate in sufficient detail the autophagy process, and suffer limitations from complex experimental setups and/or systematic errors. Here we developed a method to image, contextually, the number and pH of autophagic intermediates by using the probe mRFP-GFP-LC3B as a ratiometric pH sensor. This information is expressed functionally by AIPD, the pH distribution of the number of autophagic intermediates per cell. AIPD analysis reveals how intermediates are characterized by a continuous pH distribution, in the range 4.5–6.5, and therefore can be described by a more complex set of states rather than the usual biphasic one (autophagosomes and autolysosomes). AIPD shape and amplitude are sensitive to alterations in the autophagy pathway induced by drugs or environmental states, and allow a quantitative estimation of autophagic flux by retrieving the concentrations of autophagic intermediates.
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Affiliation(s)
- Giuseppe Maulucci
- a Istituto di Fisica; Università Cattolica del Sacro Cuore ; Rome , Italy
| | - Michela Chiarpotto
- a Istituto di Fisica; Università Cattolica del Sacro Cuore ; Rome , Italy
| | - Massimiliano Papi
- a Istituto di Fisica; Università Cattolica del Sacro Cuore ; Rome , Italy
| | - Daniela Samengo
- b Istituto di Patologia Generale; Università Cattolica del Sacro Cuore ; Rome , Italy
| | - Giovambattista Pani
- b Istituto di Patologia Generale; Università Cattolica del Sacro Cuore ; Rome , Italy
| | - Marco De Spirito
- a Istituto di Fisica; Università Cattolica del Sacro Cuore ; Rome , Italy
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24
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Hochreiter B, Garcia AP, Schmid JA. Fluorescent proteins as genetically encoded FRET biosensors in life sciences. SENSORS 2015; 15:26281-314. [PMID: 26501285 PMCID: PMC4634415 DOI: 10.3390/s151026281] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 10/08/2015] [Indexed: 12/11/2022]
Abstract
Fluorescence- or Förster resonance energy transfer (FRET) is a measurable physical energy transfer phenomenon between appropriate chromophores, when they are in sufficient proximity, usually within 10 nm. This feature has made them incredibly useful tools for many biomedical studies on molecular interactions. Furthermore, this principle is increasingly exploited for the design of biosensors, where two chromophores are linked with a sensory domain controlling their distance and thus the degree of FRET. The versatility of these FRET-biosensors made it possible to assess a vast amount of biological variables in a fast and standardized manner, allowing not only high-throughput studies but also sub-cellular measurements of biological processes. In this review, we aim at giving an overview over the recent advances in genetically encoded, fluorescent-protein based FRET-biosensors, as these represent the largest and most vividly growing group of FRET-based sensors. For easy understanding, we are grouping them into four categories, depending on their molecular mechanism. These are based on: (a) cleavage; (b) conformational-change; (c) mechanical force and (d) changes in the micro-environment. We also address the many issues and considerations that come with the development of FRET-based biosensors, as well as the possibilities that are available to measure them.
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Affiliation(s)
- Bernhard Hochreiter
- Institute for Vascular Biology and Thrombosis Research, Medical University Vienna, Schwarzspanierstraße17, Vienna A-1090, Austria.
| | - Alan Pardo Garcia
- Institute for Vascular Biology and Thrombosis Research, Medical University Vienna, Schwarzspanierstraße17, Vienna A-1090, Austria.
| | - Johannes A Schmid
- Institute for Vascular Biology and Thrombosis Research, Medical University Vienna, Schwarzspanierstraße17, Vienna A-1090, Austria.
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25
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A novel method to visually determine the intracellular pH of xenografted tumor in vivo by utilizing fluorescent protein as an indicator. Biochem Biophys Res Commun 2015. [DOI: 10.1016/j.bbrc.2015.07.095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Gong P, Yang Y, Yi H, Fang S, Zhang P, Sheng Z, Gao G, Gao D, Cai L. Polypeptide micelles with dual pH activatable dyes for sensing cells and cancer imaging. NANOSCALE 2014; 6:5416-5424. [PMID: 24714804 DOI: 10.1039/c4nr00519h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
pH is an important control parameter for maintenance of cell viability and tissue functions. pH monitoring provides valuable information on cell metabolic processes and the living environment. In this study, we prepared dual pH-sensitive, fluorescent dye-loaded polypeptide nanoparticles (DPNs) for ratiometric sensing of pH changes in living cells. DPNs contain two types of dyes: N-(rhodamine B) lactam cystamine (RBLC), an acid activatable fluorescent dye with increased fluorescence in an acidic environment, and fluorescein isothiocyanate (FITC), a base activatable fluorescent dye with enhanced fluorescence in an alkaline environment. Hence, DPNs exhibited a dual response signal with strong red fluorescence and weak green fluorescence under acidic conditions; in contrast, they showed strong green fluorescence and almost no red fluorescence under alkaline and neutral conditions. The favorable inverse pH responses of the two fluorescent dyes resulted in ratiometric pH determination for DPNs with an optimized pH-sensitive range of pH 4.5-7.5. Quantitative analysis of the intracellular pH of intact MCF-7 cells has been successfully demonstrated with our nanosensor. Moreover, single acid activatable fluorescent dye doped polypeptide nanoparticles that only contained RBLC can distinguish tumor tissue from normal tissue by monitoring the acidic extracellular environment.
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Affiliation(s)
- Ping Gong
- Guangdong Key Laboratory of Nanomedicine, Shenzhen Key Laboratory of Cancer Nanotechnology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, P. R. China.
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27
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Conway JRW, Carragher NO, Timpson P. Developments in preclinical cancer imaging: innovating the discovery of therapeutics. Nat Rev Cancer 2014; 14:314-28. [PMID: 24739578 DOI: 10.1038/nrc3724] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Integrating biological imaging into early stages of the drug discovery process can provide invaluable readouts of drug activity within complex disease settings, such as cancer. Iterating this approach from initial lead compound identification in vitro to proof-of-principle in vivo analysis represents a key challenge in the drug discovery field. By embracing more complex and informative models in drug discovery, imaging can improve the fidelity and statistical robustness of preclinical cancer studies. In this Review, we highlight how combining advanced imaging with three-dimensional systems and intravital mouse models can provide more informative and disease-relevant platforms for cancer drug discovery.
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Affiliation(s)
- James R W Conway
- Garvan Institute of Medical Research and The Kinghorn Cancer Centre Sydney, St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, New South Wales 2010, Sydney, Australia
| | - Neil O Carragher
- Edinburgh Cancer Research UK Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XR, UK
| | - Paul Timpson
- Garvan Institute of Medical Research and The Kinghorn Cancer Centre Sydney, St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, New South Wales 2010, Sydney, Australia
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28
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Abstract
Fluorescent timers (FTs) are fluorescent proteins that change color with time. FTs can be used as tags to follow protein dynamics in living cells. Recently we described a novel class of FTs called tandem fluorescent protein timers (tFTs). Each tFT is a tandem fusion of two different conventional fluorescent proteins having distinct kinetics of fluorophore maturation. tFTs suitable for studying protein dynamics on different scales can be generated from a broad range of commonly used fluorescent proteins. Here we describe how to establish new tFTs and consider potential pitfalls. We detail a protocol for quantitative fluorescence microscopy imaging and analysis of intracellular protein dynamics with tFTs in the budding yeast Saccharomyces cerevisiae.
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29
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Benčina M. Illumination of the spatial order of intracellular pH by genetically encoded pH-sensitive sensors. SENSORS 2013; 13:16736-58. [PMID: 24316570 PMCID: PMC3892890 DOI: 10.3390/s131216736] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 11/27/2013] [Accepted: 11/27/2013] [Indexed: 12/11/2022]
Abstract
Fluorescent proteins have been extensively used for engineering genetically encoded sensors that can monitor levels of ions, enzyme activities, redox potential, and metabolites. Certain fluorescent proteins possess specific pH-dependent spectroscopic features, and thus can be used as indicators of intracellular pH. Moreover, concatenated pH-sensitive proteins with target proteins pin the pH sensors to a definite location within the cell, compartment, or tissue. This study provides an overview of the continually expanding family of pH-sensitive fluorescent proteins that have become essential tools for studies of pH homeostasis and cell physiology. We describe and discuss the design of intensity-based and ratiometric pH sensors, their spectral properties and pH-dependency, as well as their performance. Finally, we illustrate some examples of the applications of pH sensors targeted at different subcellular compartments.
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Affiliation(s)
- Mojca Benčina
- Laboratory of Biotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia.
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Raimondo JV, Joyce B, Kay L, Schlagheck T, Newey SE, Srinivas S, Akerman CJ. A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system. Front Cell Neurosci 2013; 7:202. [PMID: 24312004 PMCID: PMC3826072 DOI: 10.3389/fncel.2013.00202] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 10/17/2013] [Indexed: 01/08/2023] Open
Abstract
Within the nervous system, intracellular Cl− and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl− and pH are often co-regulated, and network activity results in the movement of both Cl− and H+. Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl− and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN—a new genetically-encoded ratiometric Cl− and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl− and H+ concentrations under a variety of conditions. In addition, we establish the sensor's utility by characterizing activity-dependent ion dynamics in hippocampal neurons.
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Affiliation(s)
- Joseph V Raimondo
- Department of Pharmacology, University of Oxford Oxford, UK ; UCT/MRC Receptor Biology Unit, Division of Medical Biochemistry, Faculty of Health Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town Cape Town, South Africa
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Ueda Y, Kwok S, Hayashi Y. Application of FRET probes in the analysis of neuronal plasticity. Front Neural Circuits 2013; 7:163. [PMID: 24133415 PMCID: PMC3794420 DOI: 10.3389/fncir.2013.00163] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/23/2013] [Indexed: 12/12/2022] Open
Abstract
Breakthroughs in imaging techniques and optical probes in recent years have revolutionized the field of life sciences in ways that traditional methods could never match. The spatial and temporal regulation of molecular events can now be studied with great precision. There have been several key discoveries that have made this possible. Since green fluorescent protein (GFP) was cloned in 1992, it has become the dominant tracer of proteins in living cells. Then the evolution of color variants of GFP opened the door to the application of Förster resonance energy transfer (FRET), which is now widely recognized as a powerful tool to study complicated signal transduction events and interactions between molecules. Employment of fluorescent lifetime imaging microscopy (FLIM) allows the precise detection of FRET in small subcellular structures such as dendritic spines. In this review, we provide an overview of the basic and practical aspects of FRET imaging and discuss how different FRET probes have revealed insights into the molecular mechanisms of synaptic plasticity and enabled visualization of neuronal network activity both in vitro and in vivo.
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Raimondo JV, Irkle A, Wefelmeyer W, Newey SE, Akerman CJ. Genetically encoded proton sensors reveal activity-dependent pH changes in neurons. Front Mol Neurosci 2012; 5:68. [PMID: 22666186 PMCID: PMC3364509 DOI: 10.3389/fnmol.2012.00068] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 05/13/2012] [Indexed: 02/05/2023] Open
Abstract
The regulation of hydrogen ion concentration (pH) is fundamental to cell viability, metabolism, and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission, and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilized to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E2GFP, and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons.
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Okumoto S. Quantitative imaging using genetically encoded sensors for small molecules in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:108-17. [PMID: 22449046 DOI: 10.1111/j.1365-313x.2012.04910.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Quantitative imaging in live cells is a powerful method for monitoring the dynamics of biomolecules at an excellent spatio-temporal resolution. Such an approach, initially limited to a small number of substrates for which specific dyes were available, has become possible for a large number of biomolecules due to the development of genetically encoded, protein-based sensors. These sensors, which can be introduced into live cells through a transgenic approach, offer the benefits of quantitative imaging, with an extra advantage of non-invasiveness. In the past decade there has been a drastic expansion in the number of biomolecules for which genetically encoded sensors are available, and the functional properties of existing sensors are being improved at a dramatic pace. A number of technical improvements have now made the application of genetically encoded sensors in plants rather straightforward, and some of the sensors such as calcium indicator proteins have become standard analytical tools in many plant laboratories. The use of a handful of probes has already revealed an amazing specificity of cellular biomolecule dynamics in plants, which leads us to believe that there are many more discoveries to be made using genetically encoded sensors. In this short review, we will summarize the progress made in the past 15 years in the development in genetically encoded sensors, and highlight significant discoveries made in plant biology.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
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Ogata M, Awaji T, Iwasaki N, Fujimaki R, Takizawa M, Maruyama K, Iwamoto Y, Uchigata Y. A new mitochondrial pH biosensor for quantitative assessment of pancreatic β-cell function. Biochem Biophys Res Commun 2012; 421:20-6. [DOI: 10.1016/j.bbrc.2012.03.093] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 03/16/2012] [Indexed: 10/28/2022]
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Okumoto S, Jones A, Frommer WB. Quantitative imaging with fluorescent biosensors. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:663-706. [PMID: 22404462 DOI: 10.1146/annurev-arplant-042110-103745] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Molecular activities are highly dynamic and can occur locally in subcellular domains or compartments. Neighboring cells in the same tissue can exist in different states. Therefore, quantitative information on the cellular and subcellular dynamics of ions, signaling molecules, and metabolites is critical for functional understanding of organisms. Mass spectrometry is generally used for monitoring ions and metabolites; however, its temporal and spatial resolution are limited. Fluorescent proteins have revolutionized many areas of biology-e.g., fluorescent proteins can report on gene expression or protein localization in real time-yet promoter-based reporters are often slow to report physiologically relevant changes such as calcium oscillations. Therefore, novel tools are required that can be deployed in specific cells and targeted to subcellular compartments in order to quantify target molecule dynamics directly. We require tools that can measure enzyme activities, protein dynamics, and biophysical processes (e.g., membrane potential or molecular tension) with subcellular resolution. Today, we have an extensive suite of tools at our disposal to address these challenges, including translocation sensors, fluorescence-intensity sensors, and Förster resonance energy transfer sensors. This review summarizes sensor design principles, provides a database of sensors for more than 70 different analytes/processes, and gives examples of applications in quantitative live cell imaging.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA
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Newman RH, Fosbrink MD, Zhang J. Genetically encodable fluorescent biosensors for tracking signaling dynamics in living cells. Chem Rev 2011; 111:3614-66. [PMID: 21456512 PMCID: PMC3092831 DOI: 10.1021/cr100002u] [Citation(s) in RCA: 260] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Robert H. Newman
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Matthew D. Fosbrink
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Mahon MJ. pHluorin2: an enhanced, ratiometric, pH-sensitive green florescent protein. ACTA ACUST UNITED AC 2011; 2:132-137. [PMID: 21841969 DOI: 10.4236/abb.2011.23021] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Green florescent protein (GFP) variants that are sensitive to changes in pH are invaluable reagents for the analysis of protein dynamics associated with both endo- and exocytotic vesicular trafficking. Ratiometric pHluorin is a GFP variant that displays a bimodal excitation spectrum with peaks at 395 and 475 nm and an emission maximum at 509 nm. Upon acidification, pHluorin excitation at 395 nm decreases with a corresponding increase in the excitation at 475 nm. GFP2, a GFP variant that contains mammalianized codons and the folding enhancing mutation F64L, displays ~8-fold higher florescence compared to pHluorin upon excitation at 395 nm. Using GFP2 as a template, an enhanced ratiometric pHluorin (pHluorin2) construct was developed to contain fully mammalianized codons, the F64L mutation and ten of the thirteen pHluorin-specific mutations. As a result, pHluorin2 displays markedly higher florescence when compared to pHluorin while maintaining the ratiometric pH-sensitivity. Unlike native pHluorin, pHluorin2 expressed in the ligand-binding domain of the parathyroid hormone 1 receptor is readily detectable by confocal microscopy and displays a marked increase in florescence upon ligand-induced endocytosis to intracellular vesicles. Thus, pHluorin2's enhanced florescence while sustaining ratiometric pH-sensitivity represents a significant improvement for this methodological approach.
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Affiliation(s)
- Matthew J Mahon
- Endocrine Unit, Massachusetts General Hospital and Department of Medicine, Harvard Medical School
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Fluorescent Proteins as a Visible Molecular Signal for Rapid Quantification of Bioprocesses: Potential and Challenges. Chin J Chem Eng 2010. [DOI: 10.1016/s1004-9541(09)60140-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Chudakov DM, Matz MV, Lukyanov S, Lukyanov KA. Fluorescent proteins and their applications in imaging living cells and tissues. Physiol Rev 2010; 90:1103-63. [PMID: 20664080 DOI: 10.1152/physrev.00038.2009] [Citation(s) in RCA: 924] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Green fluorescent protein (GFP) from the jellyfish Aequorea victoria and its homologs from diverse marine animals are widely used as universal genetically encoded fluorescent labels. Many laboratories have focused their efforts on identification and development of fluorescent proteins with novel characteristics and enhanced properties, resulting in a powerful toolkit for visualization of structural organization and dynamic processes in living cells and organisms. The diversity of currently available fluorescent proteins covers nearly the entire visible spectrum, providing numerous alternative possibilities for multicolor labeling and studies of protein interactions. Photoactivatable fluorescent proteins enable tracking of photolabeled molecules and cells in space and time and can also be used for super-resolution imaging. Genetically encoded sensors make it possible to monitor the activity of enzymes and the concentrations of various analytes. Fast-maturing fluorescent proteins, cell clocks, and timers further expand the options for real time studies in living tissues. Here we focus on the structure, evolution, and function of GFP-like proteins and their numerous applications for in vivo imaging, with particular attention to recent techniques.
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Can Hg(II) be Determined via Quenching of the Emission of Green Fluorescent Protein from Anemonia sulcata var. smaragdina? Appl Biochem Biotechnol 2008; 158:51-8. [DOI: 10.1007/s12010-008-8435-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Accepted: 11/06/2008] [Indexed: 11/25/2022]
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Green fluorescent protein based pH indicators for in vivo use: a review. Anal Bioanal Chem 2008; 393:1107-22. [DOI: 10.1007/s00216-008-2515-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2008] [Revised: 11/03/2008] [Accepted: 11/05/2008] [Indexed: 10/21/2022]
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Urra J, Sandoval M, Cornejo I, Barros LF, Sepúlveda FV, Cid LP. A genetically encoded ratiometric sensor to measure extracellular pH in microdomains bounded by basolateral membranes of epithelial cells. Pflugers Arch 2008; 457:233-42. [PMID: 18427834 DOI: 10.1007/s00424-008-0497-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 03/03/2008] [Accepted: 03/17/2008] [Indexed: 02/05/2023]
Abstract
Extracellular pH, especially in relatively inaccessible microdomains between cells, affects transport membrane protein activity and might have an intercellular signaling role. We have developed a genetically encoded extracellular pH sensor capable of detecting pH changes in basolateral spaces of epithelial cells. It consists of a chimerical membrane protein displaying concatenated enhanced variants of cyan fluorescence protein (ECFP) and yellow fluorescence protein (EYFP) at the external aspect of the cell surface. The construct, termed pHCECSensor01, was targeted to basolateral membranes of Madin-Darby canine kidney (MDCK) cells by means of a sequence derived from the aquaporin AQP4. The fusion of pH-sensitive EYFP with pH-insensitive ECFP allows ratiometric pH measurements. The titration curve of pHCECSensor01 in vivo had a pK (a) value of 6.5 +/- 0.04. Only minor effects of extracellular chloride on pHCECSensor01 were observed around the physiological concentrations of this anion. In MDCK cells, the sensor was able to detect changes in pH secondary to H(+) efflux into the basolateral spaces elicited by an ammonium prepulse or lactate load. This genetically encoded sensor has the potential to serve as a noninvasive tool for monitoring changes in extracellular pH microdomains in epithelial and other tissues in vivo.
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Affiliation(s)
- Javier Urra
- Centro de Estudios Científicos, Av. Arturo Prat 514, Valdivia, Chile
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Ito M, Shikano T, Oda S, Horiguchi T, Tanimoto S, Awaji T, Mitani H, Miyazaki S. Difference in Ca2+ oscillation-inducing activity and nuclear translocation ability of PLCZ1, an egg-activating sperm factor candidate, between mouse, rat, human, and medaka fish. Biol Reprod 2008; 78:1081-90. [PMID: 18322275 DOI: 10.1095/biolreprod.108.067801] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Mouse phospholipase C, zeta 1 (PLCZ1), a strong candidate of egg-activating sperm factor, induces Ca(2+) oscillations and accumulates into formed pronucleus (PN) when expressed by cRNA injection. These activities were compared among mouse and human PLCZ1, newly cloned rat Plcz1, and medaka fish plcz1. The PLCZ1 proteins of the four species have an approximately homologous sequence of nuclear localization signal. However, the nuclear translocation ability was defective in rat, human, and medaka PLCZ1 expressed in mouse eggs. Rat PLCZ1 could not enter rat PN, whereas mouse PLCZ1 could. Mouse and human PLCZ1 translocated into the nucleus of COS-7 cells transfected with cDNA. There was little medaka PLCZ1 accumulated in the nucleus, and rat PLCZ1 was never located in the nucleus. All PLCZ1 proteins including fish could induce Ca(2+) oscillations in mouse eggs, but the activity was variable in the order of human >> mouse > medaka >> rat, estimated from minimal RNA concentration to induce Ca(2+) spikes. Ca(2+) oscillations by human PLCZ1 continued far beyond the time of PN formation (T(PN)), whereas those by mouse PLCZ1 ceased slightly before T(PN). High-frequency Ca(2+) spikes by overexpressed rat PLCZ1 stopped far before T(PN), possibly by feedback inhibition. Ca(2+) oscillations by fertilization of rat eggs stopped at T(PN), despite defective nuclear translocation of rat PLCZ1. Thus, PLCZ1 sequestration into PN participates in termination of Ca(2+) oscillations at the interphase of mouse embryos but does not always operate in other mammals, notably in rat embryos.
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Affiliation(s)
- Masahiko Ito
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo 162-8666, Japan.
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Bizzarri R, Arcangeli C, Arosio D, Ricci F, Faraci P, Cardarelli F, Beltram F. Development of a novel GFP-based ratiometric excitation and emission pH indicator for intracellular studies. Biophys J 2007; 90:3300-14. [PMID: 16603505 PMCID: PMC1432127 DOI: 10.1529/biophysj.105.074708] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report on the development of the F64L/S65T/T203Y/L231H GFP mutant (E2GFP) as an effective ratiometric pH indicator for intracellular studies. E2GFP shows two distinct spectral forms that are convertible upon pH changes both in excitation and in emission with pK close to 7.0. The excitation of the protein at 488 and 458 nm represents the best choice in terms of signal dynamic range and ratiometric deviation from the thermodynamic pK. This makes E2GFP ideally suited for imaging setups equipped with the most widespread light sources and filter settings. We used E2GFP to determine the average intracellular pH (pH(i)) and spatial pH(i) maps in two different cell lines, CHO and U-2 OS, under physiological conditions. In CHO, we monitored the evolution of the pH(i) during mitosis. We also showed the possibility to target specific subcellular compartments such as nucleoli (by fusing E2GFP with the transactivator protein of HIV, (Tat) and nuclear promyelocytic leukemia bodies (by coexpression of promyelocytic leukemia protein).
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Kuroda K, Ito M, Shikano T, Awaji T, Yoda A, Takeuchi H, Kinoshita K, Miyazaki S. The Role of X/Y Linker Region and N-terminal EF-hand Domain in Nuclear Translocation and Ca2+ Oscillation-inducing Activities of Phospholipase Cζ, a Mammalian Egg-activating Factor. J Biol Chem 2006; 281:27794-805. [PMID: 16854985 DOI: 10.1074/jbc.m603473200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sperm-specific phospholipase C-zeta (PLCzeta) causes intracellular Ca(2+) oscillations and thereby egg activation and is accumulated into the formed pronucleus (PN) when expressed in mouse eggs by injection of cRNA encoding PLCzeta, which consists of four EF-hand domains (EF1-EF4) in the N terminus, X and Y catalytic domains, and C-terminal C2 domain. Those activities were analyzed by expressing PLCzeta mutants tagged with fluorescent protein Venus by injection of cRNA into unfertilized eggs or 1-cell embryos after fertilization. Nuclear localization signal (NLS) existed at 374-381 in the X/Y linker region. Nuclear translocation was lost by replacement of Arg(376), Lys(377), Arg(378), Lys(379), or Lys(381) with glutamate, whereas Ca(2+) oscillations were conserved. Nuclear targeting was also absent for point mutation of Lys(299) and/or Lys(301) in the C terminus of X domain, or Trp(13), Phe(14), or Val(18) in the N terminus of EF1. Ca(2+) oscillation-inducing activity was lost by the former mutation and was remarkably inhibited by the latter. A short sequence 374-383 fused with Venus showed active translocation into the nucleus of COS-7 cells, but 296-309 or 1-19 did not. Despite the presence of these special regions, both activities were deprived by deletion of not only EF1 but also EF2-4 or C2 domain. Thus, PLCzeta is driven into the nucleus primarily by the aid of NLS and putative regulatory sites, but coordinated three-dimensional structure, possibly formed by a folding in the X/Y linker and close EF/C2 contact as in PLCdelta1, seems to be required not only for enzymatic activity but also for nuclear translocation ability.
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Affiliation(s)
- Keiji Kuroda
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo 162-8666, Japan
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Bohnert S, Schiavo G. Tetanus Toxin Is Transported in a Novel Neuronal Compartment Characterized by a Specialized pH Regulation. J Biol Chem 2005; 280:42336-44. [PMID: 16236708 DOI: 10.1074/jbc.m506750200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Tetanus toxin binds specifically to motor neurons at the neuromuscular junction. There, it is internalized into vesicular carriers undergoing fast retrograde transport to the spinal cord. Despite the importance of this axonal transport pathway in health and disease, its molecular and biophysical characterization is presently lacking. We sought to fill this gap by determining the pH regulation of this compartment in living motor neurons using a chimera of the tetanus toxin binding fragment (TeNT HC) and a pH-sensitive variant of the green fluorescent protein (ratiometric pHluorin). We have demonstrated that moving retrograde carriers display a narrow range of neutral pH values, which is kept constant during transport. Stationary TeNT HC-positive organelles instead exhibit a wide spectrum of pH values, ranging from acidic to neutral. This distinct pH regulation is due to a differential targeting of the vacuolar (H+) ATPase, which is not present on moving TeNT HC compartments. Accordingly, inhibition of the vacuolar (H+) ATPase under conditions that completely abolish the intracellular accumulation of acidotrophic dyes does not affect axonal retrograde transport of TeNT HC. However, a functional vacuolar (H+) ATPase is required for early steps of TeNT HC trafficking following endocytosis, and it is localized to axonal vesicles containing TeNT HC. Altogether, these findings indicate that the vacuolar (H+ ATPase plays a specific role in early sorting events directing TeNT HC to axonal carriers but not in their subsequent progression along the retrograde transport route, which escapes acidification and targeting to degradative organelles.
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Affiliation(s)
- Stephanie Bohnert
- Molecular NeuroPathobiology Laboratory, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom
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47
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Long YJ, Li YF, Huang CZ. A wide dynamic range detection of biopolymer medicines with resonance light scattering and absorption ratiometry. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2005.07.062] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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van Roermund CWT, de Jong M, IJlst L, van Marle J, Dansen TB, Wanders RJA, Waterham HR. The peroxisomal lumen in Saccharomyces cerevisiae is alkaline. J Cell Sci 2005; 117:4231-7. [PMID: 15316083 DOI: 10.1242/jcs.01305] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Peroxisomes have a central function in lipid metabolism, including the beta-oxidation of various fatty acids. The products and substrates involved in the beta-oxidation have to cross the peroxisomal membrane, which previously has been demonstrated to constitute a closed barrier, implying the existence of specific transport mechanisms. Fatty acid transport across the yeast peroxisomal membrane may follow two routes: one for activated fatty acids, dependent on the peroxisomal ABC half transporter proteins Pxa1p and Pxa2p, and one for free fatty acids, which depends on the peroxisomal acyl-CoA synthetase Faa2p and the ATP transporter Ant1p. A proton gradient across the peroxisomal membrane as part of a proton motive force has been proposed to be required for proper peroxisomal function, but the nature of the peroxisomal pH has remained inconclusive and little is known about its generation. To determine the pH of Sacharomyces cerevisiae peroxisomes in vivo, we have used two different pH-sensitive yellow fluorescent proteins targeted to the peroxisome by virtue of a C-terminal SKL and found the peroxisomal matrix in wild-type cells to be alkaline (pH(per) 8.2), while the cytosolic pH was neutral (pH(cyt) 7.0). No Delta pH was present in ant1 Delta cells, indicating that the peroxisomal pH is regulated in an ATP-dependent way and suggesting that Ant1p activity is directly involved in maintenance of the peroxisomal pH. Moreover, we found a high peroxisomal pH of >8.6 in faa2 Delta cells, while the peroxisomal pH remained 8.1+/-0.2 in pxa2 Delta cells. Our combined results suggest that the proton gradient across the peroxisomal membrane is dependent on Ant1p activity and required for the beta-oxidation of medium chain fatty acids.
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Affiliation(s)
- Carlo W T van Roermund
- Department of Clinical Chemistry, University of Amsterdam, Academic Medical Centre, PO Box 22700, 1100 DE, Amsterdam, The Netherlands.
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Klyachko NL, Shchedrina VA, Efimov AV, Kazakov SV, Gazaryan IG, Kristal BS, Brown AM. pH-dependent substrate preference of pig heart lipoamide dehydrogenase varies with oligomeric state: response to mitochondrial matrix acidification. J Biol Chem 2005; 280:16106-14. [PMID: 15710613 DOI: 10.1074/jbc.m414285200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cycling of intracellular pH has recently been shown to play a critical role in ischemia-reperfusion injury. Ischemia-reperfusion also leads to mitochondrial matrix acidification and dysfunction. However, the mechanism by which matrix acidification contributes to mitochondrial dysfunction, oxidative stress, and the resultant cellular injury has not been elucidated. We observe pH-dependent equilibria between monomeric, dimeric, and a previously undescribed tetrameric form of pig heart lipoamide dehydrogenase (LADH), a mitochondrial matrix enzyme. Dynamic light scattering studies of native LADH in aqueous solution indicate that lowering pH favors a shift in average molecular mass from higher oligomeric states to monomer. Sedimentation velocity of LADH entrapped in reverse micelles reveals dimer and tetramer at both pH 5.8 and 7.5, but monomer was observed only at pH 5.8. Enzyme activity measurements in reverse Aerosol OT micelles in octane indicate that LADH dimer and tetramer possess lipoamide dehydrogenase and diaphorase activities at pH 7.5. Upon acidification to pH 5.8 only the LADH monomer is active and only the diaphorase activity is observed. These results indicate a correlation between pH-dependent changes in the LADH reaction specificity and its oligomeric state. The acidification of mitochondrial matrix that occurs during ischemia-reperfusion injury is sufficient to alter the structure and enzymatic specificity of LADH, thereby reducing mitochondrial defenses, increasing oxidative stress, and slowing the recovery of energy metabolism. Matrix acidification may also disrupt the quaternary structure of other mitochondrial protein complexes critical for cellular homeostasis and survival.
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Affiliation(s)
- Natalia L Klyachko
- Department of Chemical Enzymology, M. V. Lomonosov Moscow State University, 119899 Moscow, Russia
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Hirasawa A, Tsumaya K, Awaji T, Katsuma S, Adachi T, Yamada M, Sugimoto Y, Miyazaki S, Tsujimoto G. Free fatty acids regulate gut incretin glucagon-like peptide-1 secretion through GPR120. Nat Med 2004; 11:90-4. [PMID: 15619630 DOI: 10.1038/nm1168] [Citation(s) in RCA: 1114] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2004] [Accepted: 11/22/2004] [Indexed: 12/11/2022]
Abstract
Diabetes, a disease in which the body does not produce or use insulin properly, is a serious global health problem. Gut polypeptides secreted in response to food intake, such as glucagon-like peptide-1 (GLP-1), are potent incretin hormones that enhance the glucose-dependent secretion of insulin from pancreatic beta cells. Free fatty acids (FFAs) provide an important energy source and also act as signaling molecules in various cellular processes, including the secretion of gut incretin peptides. Here we show that a G-protein-coupled receptor, GPR120, which is abundantly expressed in intestine, functions as a receptor for unsaturated long-chain FFAs. Furthermore, we show that the stimulation of GPR120 by FFAs promotes the secretion of GLP-1 in vitro and in vivo, and increases circulating insulin. Because GLP-1 is the most potent insulinotropic incretin, our results indicate that GPR120-mediated GLP-1 secretion induced by dietary FFAs is important in the treatment of diabetes.
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Affiliation(s)
- Akira Hirasawa
- Department of Molecular, Cell Pharmacology, National Research Institute for Child Health and Development, 3-35-31, Taishi-do, Setagaya-ku, Tokyo 154-8567, Japan
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