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Fukushima SI, Wazawa T, Sugiura K, Nagai T. Extremely Sensitive Genetically Encoded Temperature Indicator Enabling Measurement at the Organelle Level. ACS Sens 2024. [PMID: 39042704 DOI: 10.1021/acssensors.3c02658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Intracellular temperature is a fundamental parameter in biochemical reactions. Genetically encoded fluorescent temperature indicators (GETIs) have been developed to visualize intracellular thermogenesis; however, the temperature sensitivity or localization capability in specific organelles should have been further improved to clearly capture when and where intracellular temperature changes at the subcellular level occur. Here, we developed a new GETI, gMELT, composed of donor and acceptor subunits, in which cyan and yellow fluorescent proteins, respectively, as a Förster resonance energy transfer (FRET) pair were fused with temperature-sensitive domains. The donor and acceptor subunits associated and dissociated in response to temperature changes, altering the FRET efficiency. Consequently, gMELT functioned as a fluorescence ratiometric indicator. Untagged gMELT was expressed in the cytoplasm, whereas versions fused with specific localization signals were targeted to the endoplasmic reticulum (ER) or mitochondria. All gMELT variations enabled more sensitive temperature measurements in cellular compartments than those in previous GETIs. The gMELTs, tagged with ER or mitochondrial targeting sequences, were used to detect thermogenesis in organelles stimulated chemically, a method previously known to induce thermogenesis. The observed temperature changes were comparable to previous reports, assuming that the fluorescence readout changes were exclusively due to temperature variations. Furthermore, we demonstrated how macromolecular crowding influences gMELT fluorescence given that this factor can subtly affect the fluorescence readout. Investigating thermogenesis with gMELT, accounting for factors such as macromolecular crowding, will enhance our understanding of intracellular thermogenesis phenomena.
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Affiliation(s)
| | | | | | - Takeharu Nagai
- SANKEN, The University of Osaka, Ibaraki, Osaka 567-0047, Japan
- OTRI, The University of Osaka, Suita, Osaka 565-0871, Japan
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
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2
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Frei MS, Mehta S, Zhang J. Next-Generation Genetically Encoded Fluorescent Biosensors Illuminate Cell Signaling and Metabolism. Annu Rev Biophys 2024; 53:275-297. [PMID: 38346245 DOI: 10.1146/annurev-biophys-030722-021359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Genetically encoded fluorescent biosensors have revolutionized the study of cell signaling and metabolism, as they allow for live-cell measurements with high spatiotemporal resolution. This success has spurred the development of tailor-made biosensors that enable the study of dynamic phenomena on different timescales and length scales. In this review, we discuss different approaches to enhancing and developing new biosensors. We summarize the technologies used to gain structural insights into biosensor design and comment on useful screening technologies. Furthermore, we give an overview of different applications where biosensors have led to key advances over recent years. Finally, we give our perspective on where future work is bound to make a large impact.
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Affiliation(s)
- Michelle S Frei
- Department of Pharmacology, University of California San Diego, La Jolla, California, USA; , ,
| | - Sohum Mehta
- Department of Pharmacology, University of California San Diego, La Jolla, California, USA; , ,
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego, La Jolla, California, USA; , ,
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, California, USA
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
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3
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Wu J, Shindo Y, Hotta K, Vu CQ, Lu K, Wazawa T, Nagai T, Oka K. Calcium-induced upregulation of energy metabolism heats neurons during neural activity. Biochem Biophys Res Commun 2024; 708:149799. [PMID: 38522401 DOI: 10.1016/j.bbrc.2024.149799] [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: 02/06/2024] [Revised: 02/13/2024] [Accepted: 03/16/2024] [Indexed: 03/26/2024]
Abstract
Cellular temperature affects every biochemical reaction, underscoring its critical role in cellular functions. In neurons, temperature not only modulates neurotransmission but is also a key determinant of neurodegenerative diseases. Considering that the brain consumes a disproportionately high amount of energy relative to its weight, neural circuits likely generate a lot of heat, which can increase cytosolic temperature. However, the changes in temperature within neurons and the mechanisms of heat generation during neural excitation remain unclear. In this study, we achieved simultaneous imaging of Ca2+ and temperature using the genetically encoded indicators, B-GECO and B-gTEMP. We then compared the spatiotemporal distributions of Ca2+ responses and temperature. Following neural excitation induced by veratridine, an activator of the voltage-gated Na+ channel, we observed an approximately 2 °C increase in cytosolic temperature occurring 30 s after the Ca2+ response. The temperature elevation was observed in the non-nuclear region, while Ca2+ increased throughout the cell body. Moreover, this temperature increase was suppressed under Ca2+-free conditions and by inhibitors of ATP synthesis. These results indicate that Ca2+-induced upregulation of energy metabolism serves as the heat source during neural excitation.
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Affiliation(s)
- Jiayang Wu
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Yutaka Shindo
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan; School of Frontier Engineering, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan
| | - Kohji Hotta
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan
| | - Cong Quang Vu
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Kai Lu
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Tetsuichi Wazawa
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Takeharu Nagai
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
| | - Kotaro Oka
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan; School of Frontier Engineering, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan; Waseda Research Institute for Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo, 162-8480, Japan.
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Benman W, Iyengar P, Mumford T, Huang Z, Bugaj LJ. Multiplexed dynamic control of temperature to probe and observe mammalian cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.18.580877. [PMID: 38562729 PMCID: PMC10983861 DOI: 10.1101/2024.02.18.580877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Temperature is a critical parameter for biological function, yet there is a lack of approaches to modulate the temperature of biological specimens in a dynamic and high-throughput manner. We present the thermoPlate, a device for programmable control of temperature in each well of a 96-well plate, in a manner compatible with mammalian cell culture and live cell imaging. The thermoPlate maintains precise feedback control of temperature patterns independently in each well, with minutes-scale heating and cooling through ΔT ~15-20°C. A computational model that predicts thermal diffusion guides optimal design of heating protocols. The thermoPlate allowed systematic characterization of both synthetic and natural thermo-responsive systems. We first used the thermoPlate in conjunction with live-cell microscopy to characterize the rapid temperature-dependent phase separation of a synthetic elastin-like polypeptide (ELP53). We then measured stress granule (SG) formation in response to heat stress, observing differences in SG dynamics with each increasing degree of stress. We observed adaptive formation of SGs, whereby SGs formed but then dissolved in response to persistent heat stress (≥ 42°C). SG adaptation revealed a biochemical memory of stress that depended on both the time and temperature of heat shock. Stress memories continued to form even after the removal of heat and persisted for 6-9 hours before dissipating. The capabilities and open-source nature of the thermoPlate will empower the study and engineering of a wide range of thermoresponsive phenomena.
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Affiliation(s)
- William Benman
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Pavan Iyengar
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Thomas Mumford
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Zikang Huang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lukasz J. Bugaj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute of Regenerative Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Vu CQ, Arai S. Quantitative Imaging of Genetically Encoded Fluorescence Lifetime Biosensors. BIOSENSORS 2023; 13:939. [PMID: 37887132 PMCID: PMC10605767 DOI: 10.3390/bios13100939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023]
Abstract
Genetically encoded fluorescence lifetime biosensors have emerged as powerful tools for quantitative imaging, enabling precise measurement of cellular metabolites, molecular interactions, and dynamic cellular processes. This review provides an overview of the principles, applications, and advancements in quantitative imaging with genetically encoded fluorescence lifetime biosensors using fluorescence lifetime imaging microscopy (go-FLIM). We highlighted the distinct advantages of fluorescence lifetime-based measurements, including independence from expression levels, excitation power, and focus drift, resulting in robust and reliable measurements compared to intensity-based approaches. Specifically, we focus on two types of go-FLIM, namely Förster resonance energy transfer (FRET)-FLIM and single-fluorescent protein (FP)-based FLIM biosensors, and discuss their unique characteristics and benefits. This review serves as a valuable resource for researchers interested in leveraging fluorescence lifetime imaging to study molecular interactions and cellular metabolism with high precision and accuracy.
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Affiliation(s)
- Cong Quang Vu
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Satoshi Arai
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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Inada N. A Guide to Plant Intracellular Temperature Imaging using Fluorescent Thermometers. PLANT & CELL PHYSIOLOGY 2023; 64:7-18. [PMID: 36039974 DOI: 10.1093/pcp/pcac123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 07/06/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
All aspects of plant physiology are influenced by temperature. Changes in environmental temperature alter the temperatures of plant tissues and cells, which then affect various cellular activities, such as gene expression, protein stability and enzyme activities. In turn, changes in cellular activities, which are associated with either exothermic or endothermic reactions, can change the local temperature in cells and tissues. In the past 10 years, a number of fluorescent probes that detect temperature and enable intracellular temperature imaging have been reported. Intracellular temperature imaging has revealed that there is a temperature difference >1°C inside cells and that the treatment of cells with mitochondrial uncoupler or ionomycin can cause more than a 1°C intracellular temperature increase in mammalian cultured cells. Thermogenesis mechanisms in brown adipocytes have been revealed with the aid of intracellular temperature imaging. While there have been no reports on plant intracellular temperature imaging thus far, intracellular temperature imaging is expected to provide a new way to analyze the mechanisms underlying the various activities of plant cells. In this review, I will first summarize the recent progress in the development of fluorescent thermometers and their biological applications. I will then discuss the selection of fluorescent thermometers and experimental setup for the adaptation of intracellular temperature imaging to plant cells. Finally, possible applications of intracellular temperature imaging to investigate plant cell functions will be discussed.
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Affiliation(s)
- Noriko Inada
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka, 599-8531 Japan
- School of Agriculture, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka, 599-8531 Japan
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Liu X, Yamazaki T, Kwon HY, Arai S, Chang YT. A palette of site-specific organelle fluorescent thermometers. Mater Today Bio 2022; 16:100405. [PMID: 36060107 PMCID: PMC9434161 DOI: 10.1016/j.mtbio.2022.100405] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/04/2022]
Abstract
Intracellular micro-temperature is closely related to cellular processes. Such local temperature inside cells can be measured by fluorescent thermometers, which are a series of fluorescent materials that convert the temperature information to detectable fluorescence signals. To investigate the intracellular temperature fluctuation in various organelles, it is essential to develop site-specific organelle thermometers. In this study, we develop a new series of fluorescent thermometers, Thermo Greens (TGs), to visualize the temperature change in almost all typical organelles. Through fluorescence lifetime-based cell imaging, it was proven that TGs allow the organelle-specific monitoring of temperature gradients created by external heating. The fluorescence lifetime-based thermometry shows that each organelle experiences a distinct temperature increment which depends on the distance away from the heat source. TGs are further demonstrated in the quantitative imaging of heat production at different organelles such as mitochondria and endoplasmic reticulum in brown adipocytes. To date, TGs are the first palette batch of small molecular fluorescent thermometers that can cover almost all typical organelles. These findings can inspire the development of new fluorescent thermometers and enhance the understanding of thermal biology in the future.
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Lu K, Wazawa T, Sakamoto J, Vu CQ, Nakano M, Kamei Y, Nagai T. Intracellular Heat Transfer and Thermal Property Revealed by Kilohertz Temperature Imaging with a Genetically Encoded Nanothermometer. NANO LETTERS 2022; 22:5698-5707. [PMID: 35792763 PMCID: PMC9335883 DOI: 10.1021/acs.nanolett.2c00608] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Despite improved sensitivity of nanothermometers, direct observation of heat transport inside single cells has remained challenging for the lack of high-speed temperature imaging techniques. Here, we identified insufficient temperature resolution under short signal integration time and slow sensor kinetics as two major bottlenecks. To overcome the limitations, we developed B-gTEMP, a nanothermometer based on the tandem fusion of mNeonGreen and tdTomato fluorescent proteins. We visualized the propagation of heat inside intracellular space by tracking the temporal variation of local temperature at a time resolution of 155 μs and a temperature resolution 0.042 °C. By comparing the fast in situ temperature dynamics with computer-simulated heat diffusion, we estimated the thermal diffusivity of live HeLa cells. The present thermal diffusivity in cells was about 1/5.3 of that of water and much smaller than the values reported for bulk tissues, which may account for observations of heterogeneous intracellular temperature distributions.
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Affiliation(s)
- Kai Lu
- SANKEN
(The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Tetsuichi Wazawa
- SANKEN
(The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Joe Sakamoto
- National
Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Cong Quang Vu
- SANKEN
(The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
- Graduate
School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masahiro Nakano
- SANKEN
(The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Yasuhiro Kamei
- National
Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Takeharu Nagai
- SANKEN
(The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
- Graduate
School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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9
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Opto-thermal technologies for microscopic analysis of cellular temperature-sensing systems. Biophys Rev 2021; 14:41-54. [PMID: 35340595 PMCID: PMC8921355 DOI: 10.1007/s12551-021-00854-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 10/12/2021] [Indexed: 12/15/2022] Open
Abstract
AbstractCould enzymatic activities and their cooperative functions act as cellular temperature-sensing systems? This review introduces recent opto-thermal technologies for microscopic analyses of various types of cellular temperature-sensing system. Optical microheating technologies have been developed for local and rapid temperature manipulations at the cellular level. Advanced luminescent thermometers visualize the dynamics of cellular local temperature in space and time during microheating. An optical heater and thermometer can be combined into one smart nanomaterial that demonstrates hybrid function. These technologies have revealed a variety of cellular responses to spatial and temporal changes in temperature. Spatial temperature gradients cause asymmetric deformations during mitosis and neurite outgrowth. Rapid changes in temperature causes imbalance of intracellular Ca2+ homeostasis and membrane potential. Among those responses, heat-induced muscle contractions are highlighted. It is also demonstrated that the short-term heating hyperactivates molecular motors to exceed their maximal activities at optimal temperatures. We discuss future prospects for opto-thermal manipulation of cellular functions and contributions to obtain a deeper understanding of the mechanisms of cellular temperature-sensing systems.
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