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Kunida K, Takagi N, Aoki K, Ikeda K, Nakamura T, Sakumura Y. Decoding cellular deformation from pseudo-simultaneously observed Rho GTPase activities. Cell Rep 2023; 42:112071. [PMID: 36764299 DOI: 10.1016/j.celrep.2023.112071] [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: 10/17/2022] [Revised: 10/31/2022] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
Limitations in simultaneously observing the activity of multiple molecules in live cells prevent researchers from elucidating how these molecules coordinate the dynamic regulation of cellular functions. Here, we propose the motion-triggered average (MTA) algorithm to characterize pseudo-simultaneous dynamic changes in arbitrary cellular deformation and molecular activities. Using MTA, we successfully extract a pseudo-simultaneous time series from individually observed activities of three Rho GTPases: Cdc42, Rac1, and RhoA. To verify that this time series encoded information on cell-edge movement, we use a mathematical regression model to predict the edge velocity from the activities of the three molecules. The model accurately predicts the unknown edge velocity, providing numerical evidence that these Rho GTPases regulate edge movement. Data preprocessing using MTA combined with mathematical regression provides an effective strategy for reusing numerous individual observations of molecular activities.
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Affiliation(s)
- Katsuyuki Kunida
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 8916-5, Japan; School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Nobuhiro Takagi
- Graduate School of Information Science and Technology, Aichi Prefectural University, Nagakute, Aichi 480-1342, Japan
| | - Kazuhiro Aoki
- National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Kazushi Ikeda
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 8916-5, Japan; Data Science Center, Nara Institute of Science and Technology, Ikoma, Nara 8916-5, Japan; RIKEN Center for Advanced Intelligence Project (RIKEN AIP), Kyoto 619-0288, Japan
| | - Takeshi Nakamura
- Research Institute for Biomedical Sciences, Tokyo University of Science, Noda, Chiba 278-0022, Japan
| | - Yuichi Sakumura
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 8916-5, Japan; Data Science Center, Nara Institute of Science and Technology, Ikoma, Nara 8916-5, Japan.
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2
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Profiling cellular morphodynamics by spatiotemporal spectrum decomposition. PLoS Comput Biol 2018; 14:e1006321. [PMID: 30071020 PMCID: PMC6091976 DOI: 10.1371/journal.pcbi.1006321] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 08/14/2018] [Accepted: 06/22/2018] [Indexed: 12/12/2022] Open
Abstract
Cellular morphology and associated morphodynamics are widely used for qualitative and quantitative assessments of cell state. Here we implement a framework to profile cellular morphodynamics based on an adaptive decomposition of local cell boundary motion into instantaneous frequency spectra defined by the Hilbert-Huang transform (HHT). Our approach revealed that spontaneously migrating cells with approximately homogeneous molecular makeup show remarkably consistent instantaneous frequency distributions, though they have markedly heterogeneous mobility. Distinctions in cell edge motion between these cells are captured predominantly by differences in the magnitude of the frequencies. We found that acute photo-inhibition of Vav2 guanine exchange factor, an activator of the Rho family of signaling proteins coordinating cell motility, produces significant shifts in the frequency distribution, but does not affect frequency magnitude. We therefore concluded that the frequency spectrum encodes the wiring of the molecular circuitry that regulates cell boundary movements, whereas the magnitude captures the activation level of the circuitry. We also used HHT spectra as multi-scale spatiotemporal features in statistical region merging to identify subcellular regions of distinct motion behavior. In line with our conclusion that different HHT spectra relate to different signaling regimes, we found that subcellular regions with different morphodynamics indeed exhibit distinct Rac1 activities. This algorithm thus can serve as an accurate and sensitive classifier of cellular morphodynamics to pinpoint spatial and temporal boundaries between signaling regimes. Many studies in cell biology employ global shape descriptors to probe mechanisms of cell morphogenesis. Here, we implement a framework in this paper to profile cellular morphodynamics very locally. We employ the Hilbert-Huang transform (HHT) to extract along the entire cell edge spectra of instantaneous edge motion frequency and magnitude and use them to classify overall cell behavior as well as subcellular edge sectors of distinct dynamics. We find in fibroblast-like COS7 cells that the marked heterogeneity in mobility of an unstimulated population is fully captured by differences in the magnitude spectra, while the frequency spectra are conserved between cells. Using optogenetics to acutely inhibit morphogenetic signaling pathways we find that these molecular shifts are reflected by changes in the frequency spectra but not in the magnitude spectra. After clustering cell edge sectors with distinct morphodynamics we observe in cells expressing a Rac1 activity biosensor that the sectors with different frequency spectra associate with different signaling intensity and dynamics. Together, these observations let us conclude that the frequency spectrum encodes the wiring of the molecular circuitry that regulates edge movements, whereas the magnitude captures the activation level of the circuitry.
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3
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Yamao M, Aoki K, Yukinawa N, Ishii S, Matsuda M, Naoki H. Two New FRET Imaging Measures: Linearly Proportional to and Highly Contrasting the Fraction of Active Molecules. PLoS One 2016; 11:e0164254. [PMID: 27780260 PMCID: PMC5079603 DOI: 10.1371/journal.pone.0164254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/11/2016] [Indexed: 11/18/2022] Open
Abstract
We developed two new FRET imaging measures for intramolecular FRET biosensors, called linearly proportional (LP) and highly contrasting (HC) measures, which can be easily calculated by the fluorescence intensities of donor and acceptor as a ratio between their weighted sums. As an alternative to the conventional ratiometric measure, which non-linearly depends on the fraction of active molecule, we first developed the LP measure, which is linearly proportional to the fraction of active molecules. The LP measure inherently unmixes bleed-through signals and is robust against fluorescence noise. By extending the LP measure, we furthermore designed the HC measure, which provides highly contrasting images of the molecular activity, more than the ratiometric measure. In addition to their advantages, these measures are insensitive to the biosensor expression level, which is a fundamental property of the ratiometric measure. Using artificial data and FRET imaging data, we showed that the LP measure effectively represents the fraction of active molecules and that the HC measure improves visual interpretability by providing high contrast images of molecular activity. Therefore, the LP and HC measures allow us to gain more quantitative and qualitative insights from FRET imaging than the ratiometric measure.
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Affiliation(s)
- Masataka Yamao
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Kazuhiro Aoki
- National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Naoto Yukinawa
- Okinawa Institute of Science and Technology Graduate University, Kunigami, Okinawa, Japan
| | - Shin Ishii
- Imaging Platform for Spatio-temporal Information, Kyoto University, Sakyo, Kyoto, Japan
- Graduate School of Informatics, Kyoto University, Sakyo, Kyoto, Japan
| | - Michiyuki Matsuda
- Imaging Platform for Spatio-temporal Information, Kyoto University, Sakyo, Kyoto, Japan
- Graduate School of Medicine, Kyoto University, Sakyo, Kyoto, Japan
| | - Honda Naoki
- Imaging Platform for Spatio-temporal Information, Kyoto University, Sakyo, Kyoto, Japan
- Graduate School of Medicine, Kyoto University, Sakyo, Kyoto, Japan
- * E-mail:
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Hodgson L, Spiering D, Sabouri-Ghomi M, Dagliyan O, DerMardirossian C, Danuser G, Hahn KM. FRET binding antenna reports spatiotemporal dynamics of GDI-Cdc42 GTPase interactions. Nat Chem Biol 2016; 12:802-809. [PMID: 27501396 PMCID: PMC5030135 DOI: 10.1038/nchembio.2145] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/16/2016] [Indexed: 12/29/2022]
Abstract
Guanine-nucleotide dissociation inhibitors (GDIs) are negative regulators of Rho family GTPases that sequester the GTPases away from the membrane. Here we ask how GDI-Cdc42 interaction regulates localized Cdc42 activation for cell motility. The sensitivity of cells to overexpression of Rho family pathway components led us to a new biosensor, GDI.Cdc42 FLARE, in which Cdc42 is modified with a fluorescence resonance energy transfer (FRET) 'binding antenna' that selectively reports Cdc42 binding to endogenous GDIs. Similar antennae could also report GDI-Rac1 and GDI-RhoA interaction. Through computational multiplexing and simultaneous imaging, we determined the spatiotemporal dynamics of GDI-Cdc42 interaction and Cdc42 activation during cell protrusion and retraction. This revealed remarkably tight coordination of GTPase release and activation on a time scale of 10 s, suggesting that GDI-Cdc42 interactions are a critical component of the spatiotemporal regulation of Cdc42 activity, and not merely a mechanism for global sequestration of an inactivated pool of signaling molecules.
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Affiliation(s)
- Louis Hodgson
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine.,Department of Pharmacology and Lineberger Cancer Center, University of North Carolina at Chapel Hill
| | - Désirée Spiering
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine
| | | | - Onur Dagliyan
- Department of Pharmacology and Lineberger Cancer Center, University of North Carolina at Chapel Hill
| | | | - Gaudenz Danuser
- Department of Cell Biology, The Scripps Research Institute.,Department of Cell Biology, Harvard Medical School
| | - Klaus M Hahn
- Department of Pharmacology and Lineberger Cancer Center, University of North Carolina at Chapel Hill
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5
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Tohsato Y, Ho KHL, Kyoda K, Onami S. SSBD: a database of quantitative data of spatiotemporal dynamics of biological phenomena. Bioinformatics 2016; 32:3471-3479. [PMID: 27412095 PMCID: PMC5181557 DOI: 10.1093/bioinformatics/btw417] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 04/15/2016] [Accepted: 06/19/2016] [Indexed: 11/20/2022] Open
Abstract
Motivation: Rapid advances in live-cell imaging analysis and mathematical modeling have produced a large amount of quantitative data on spatiotemporal dynamics of biological objects ranging from molecules to organisms. There is now a crucial need to bring these large amounts of quantitative biological dynamics data together centrally in a coherent and systematic manner. This will facilitate the reuse of this data for further analysis. Results: We have developed the Systems Science of Biological Dynamics database (SSBD) to store and share quantitative biological dynamics data. SSBD currently provides 311 sets of quantitative data for single molecules, nuclei and whole organisms in a wide variety of model organisms from Escherichia coli to Mus musculus. The data are provided in Biological Dynamics Markup Language format and also through a REST API. In addition, SSBD provides 188 sets of time-lapse microscopy images from which the quantitative data were obtained and software tools for data visualization and analysis. Availability and Implementation: SSBD is accessible at http://ssbd.qbic.riken.jp. Contact:sonami@riken.jp
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Affiliation(s)
- Yukako Tohsato
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan
| | - Kenneth H L Ho
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan
| | - Koji Kyoda
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan
| | - Shuichi Onami
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan
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6
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Martin K, Reimann A, Fritz RD, Ryu H, Jeon NL, Pertz O. Spatio-temporal co-ordination of RhoA, Rac1 and Cdc42 activation during prototypical edge protrusion and retraction dynamics. Sci Rep 2016; 6:21901. [PMID: 26912264 PMCID: PMC4766498 DOI: 10.1038/srep21901] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/05/2016] [Indexed: 02/06/2023] Open
Abstract
The three canonical Rho GTPases RhoA, Rac1 and Cdc42 co-ordinate cytoskeletal dynamics. Recent studies indicate that all three Rho GTPases are activated at the leading edge of motile fibroblasts, where their activity fluctuates at subminute time and micrometer length scales. Here, we use a microfluidic chip to acutely manipulate fibroblast edge dynamics by applying pulses of platelet-derived growth factor (PDGF) or the Rho kinase inhibitor Y-27632 (which lowers contractility). This induces acute and robust membrane protrusion and retraction events, that exhibit stereotyped cytoskeletal dynamics, allowing us to fairly compare specific morphodynamic states across experiments. Using a novel Cdc42, as well as previously described, second generation RhoA and Rac1 biosensors, we observe distinct spatio-temporal signaling programs that involve all three Rho GTPases, during protrusion/retraction edge dynamics. Our results suggest that Rac1, Cdc42 and RhoA regulate different cytoskeletal and adhesion processes to fine tune the highly plastic edge protrusion/retraction dynamics that power cell motility.
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Affiliation(s)
- Katrin Martin
- Dept. of Biomedicine, University of Basel, Mattenstrasse 28, 4058 Basel, Switzerland
| | - Andreas Reimann
- Dept. of Biomedicine, University of Basel, Mattenstrasse 28, 4058 Basel, Switzerland
| | - Rafael D Fritz
- Dept. of Biomedicine, University of Basel, Mattenstrasse 28, 4058 Basel, Switzerland
| | - Hyunryul Ryu
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-742, Republic of Korea.,Institute of Advanced Machinery and Design, Seoul National University, Seoul, 151-742, Republic of Korea
| | - Noo Li Jeon
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-742, Republic of Korea.,Institute of Advanced Machinery and Design, Seoul National University, Seoul, 151-742, Republic of Korea
| | - Olivier Pertz
- Dept. of Biomedicine, University of Basel, Mattenstrasse 28, 4058 Basel, Switzerland
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7
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Gordonov S, Hwang MK, Wells A, Gertler FB, Lauffenburger DA, Bathe M. Time series modeling of live-cell shape dynamics for image-based phenotypic profiling. Integr Biol (Camb) 2016; 8:73-90. [PMID: 26658688 PMCID: PMC5058786 DOI: 10.1039/c5ib00283d] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Live-cell imaging can be used to capture spatio-temporal aspects of cellular responses that are not accessible to fixed-cell imaging. As the use of live-cell imaging continues to increase, new computational procedures are needed to characterize and classify the temporal dynamics of individual cells. For this purpose, here we present the general experimental-computational framework SAPHIRE (Stochastic Annotation of Phenotypic Individual-cell Responses) to characterize phenotypic cellular responses from time series imaging datasets. Hidden Markov modeling is used to infer and annotate morphological state and state-switching properties from image-derived cell shape measurements. Time series modeling is performed on each cell individually, making the approach broadly useful for analyzing asynchronous cell populations. Two-color fluorescent cells simultaneously expressing actin and nuclear reporters enabled us to profile temporal changes in cell shape following pharmacological inhibition of cytoskeleton-regulatory signaling pathways. Results are compared with existing approaches conventionally applied to fixed-cell imaging datasets, and indicate that time series modeling captures heterogeneous dynamic cellular responses that can improve drug classification and offer additional important insight into mechanisms of drug action. The software is available at http://saphire-hcs.org.
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Affiliation(s)
- Simon Gordonov
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- The David H. Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Mun Kyung Hwang
- The David H. Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Alan Wells
- Department of Pathology, University of Pittsburgh, and Pittsburgh VA Health System, Pittsburgh, PA, USA
| | - Frank B. Gertler
- The David H. Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Douglas A. Lauffenburger
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- The David H. Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mark Bathe
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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8
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Distinct predictive performance of Rac1 and Cdc42 in cell migration. Sci Rep 2015; 5:17527. [PMID: 26634649 PMCID: PMC4669460 DOI: 10.1038/srep17527] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/30/2015] [Indexed: 11/12/2022] Open
Abstract
We propose a new computation-based approach for elucidating how signaling molecules are decoded in cell migration. In this approach, we performed FRET time-lapse imaging of Rac1 and Cdc42, members of Rho GTPases which are responsible for cell motility, and quantitatively identified the response functions that describe the conversion from the molecular activities to the morphological changes. Based on the identified response functions, we clarified the profiles of how the morphology spatiotemporally changes in response to local and transient activation of Rac1 and Cdc42, and found that Rac1 and Cdc42 activation triggers laterally propagating membrane protrusion. The response functions were also endowed with property of differentiator, which is beneficial for maintaining sensitivity under adaptation to the mean level of input. Using the response function, we could predict the morphological change from molecular activity, and its predictive performance provides a new quantitative measure of how much the Rho GTPases participate in the cell migration. Interestingly, we discovered distinct predictive performance of Rac1 and Cdc42 depending on the migration modes, indicating that Rac1 and Cdc42 contribute to persistent and random migration, respectively. Thus, our proposed predictive approach enabled us to uncover the hidden information processing rules of Rho GTPases in the cell migration.
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9
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Kyoda K, Tohsato Y, Ho KHL, Onami S. Biological Dynamics Markup Language (BDML): an open format for representing quantitative biological dynamics data. ACTA ACUST UNITED AC 2014; 31:1044-52. [PMID: 25414366 PMCID: PMC4382901 DOI: 10.1093/bioinformatics/btu767] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 11/13/2014] [Indexed: 01/08/2023]
Abstract
Motivation: Recent progress in live-cell imaging and modeling techniques has resulted in generation of a large amount of quantitative data (from experimental measurements and computer simulations) on spatiotemporal dynamics of biological objects such as molecules, cells and organisms. Although many research groups have independently dedicated their efforts to developing software tools for visualizing and analyzing these data, these tools are often not compatible with each other because of different data formats. Results: We developed an open unified format, Biological Dynamics Markup Language (BDML; current version: 0.2), which provides a basic framework for representing quantitative biological dynamics data for objects ranging from molecules to cells to organisms. BDML is based on Extensible Markup Language (XML). Its advantages are machine and human readability and extensibility. BDML will improve the efficiency of development and evaluation of software tools for data visualization and analysis. Availability and implementation: A specification and a schema file for BDML are freely available online at http://ssbd.qbic.riken.jp/bdml/. Contact:sonami@riken.jp Supplementary Information:Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Koji Kyoda
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan and
| | - Yukako Tohsato
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan and
| | - Kenneth H L Ho
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan and
| | - Shuichi Onami
- Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan and National Bioscience Database Center, Japan Science and Technology Agency, Tokyo 102-0081, Japan
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10
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Directed migration of mesenchymal cells: where signaling and the cytoskeleton meet. Curr Opin Cell Biol 2014; 30:74-82. [PMID: 24999834 DOI: 10.1016/j.ceb.2014.06.005] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 06/13/2014] [Accepted: 06/15/2014] [Indexed: 02/04/2023]
Abstract
Cell migration directed by spatial cues, or taxis, is a primary mechanism for orchestrating concerted and collective cell movements during development, wound repair, and immune responses. Compared with the classic example of amoeboid chemotaxis, in which fast-moving cells such as neutrophils are directed by gradients of soluble factors, directed migration of slow-moving mesenchymal cells such as fibroblasts is poorly understood. Mesenchymal cells possess a distinctive organization of the actin cytoskeleton and associated adhesion complexes as its primary mechanical system, generating the asymmetric forces required for locomotion without strong polarization. The emerging hypothesis is that the molecular underpinnings of mesenchymal taxis involve distinct signaling pathways and diverse requirements for regulation.
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11
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Welf ES, Ahmed S, Johnson HE, Melvin AT, Haugh JM. Migrating fibroblasts reorient directionality by a metastable, PI3K-dependent mechanism. ACTA ACUST UNITED AC 2012; 197:105-14. [PMID: 22472441 PMCID: PMC3317800 DOI: 10.1083/jcb.201108152] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mesenchymal cell migration as exhibited by fibroblasts is distinct from amoeboid cell migration and is characterized by dynamic competition among multiple protrusions, which determines directional persistence and responses to spatial cues. Localization of phosphoinositide 3-kinase (PI3K) signaling is thought to play a broadly important role in cell motility, yet the context-dependent functions of this pathway have not been adequately elucidated. By mapping the spatiotemporal dynamics of cell protrusion/retraction and PI3K signaling monitored by total internal reflection fluorescence microscopy, we show that randomly migrating fibroblasts reorient polarity through PI3K-dependent branching and pivoting of protrusions. PI3K inhibition did not affect the initiation of newly branched protrusions, nor did it prevent protrusion induced by photoactivation of Rac. Rather, PI3K signaling increased after, not before, the onset of local protrusion and was required for the lateral spreading and stabilization of nascent branches. During chemotaxis, the branch experiencing the higher chemoattractant concentration was favored, and, thus, the cell reoriented so as to align with the external gradient.
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Affiliation(s)
- Erik S Welf
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
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12
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Kunida K, Matsuda M, Aoki K. FRET imaging and statistical signal processing reveal positive and negative feedback loops regulating the morphology of randomly migrating HT-1080 cells. J Cell Sci 2012; 125:2381-92. [PMID: 22344265 DOI: 10.1242/jcs.096859] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell migration plays an important role in many physiological processes. Rho GTPases (Rac1, Cdc42, RhoA) and phosphatidylinositols have been extensively studied in directional cell migration. However, it remains unclear how Rho GTPases and phosphatidylinositols regulate random cell migration in space and time. We have attempted to address this issue using fluorescence resonance energy transfer (FRET) imaging and statistical signal processing. First, we acquired time-lapse images of random migration of HT-1080 fibrosarcoma cells expressing FRET biosensors of Rho GTPases and phosphatidyl inositols. We developed an image-processing algorithm to extract FRET values and velocities at the leading edge of migrating cells. Auto- and cross-correlation analysis suggested the involvement of feedback regulations among Rac1, phosphatidyl inositols and membrane protrusions. To verify the feedback regulations, we employed an acute inhibition of the signaling pathway with pharmaceutical inhibitors. The inhibition of actin polymerization decreased Rac1 activity, indicating the presence of positive feedback from actin polymerization to Rac1. Furthermore, treatment with PI3-kinase inhibitor induced an adaptation of Rac1 activity, i.e. a transient reduction of Rac1 activity followed by recovery to the basal level. In silico modeling that reproduced the adaptation predicted the existence of a negative feedback loop from Rac1 to actin polymerization. Finally, we identified MLCK as the probable controlling factor in the negative feedback. These findings quantitatively demonstrate positive and negative feedback loops that involve actin, Rac1 and MLCK, and account for the ordered patterns of membrane dynamics observed in randomly migrating cells.
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Affiliation(s)
- Katsuyuki Kunida
- Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
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13
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Welf ES, Haugh JM. Stochastic models of cell protrusion arising from spatiotemporal signaling and adhesion dynamics. Methods Cell Biol 2012; 110:223-41. [PMID: 22482951 DOI: 10.1016/b978-0-12-388403-9.00009-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
During cell migration, local protrusion events are regulated by biochemical and physical processes that are in turn coordinated with the dynamic properties of cell-substratum adhesion structures. In this chapter, we present a modeling approach for integrating the apparent stochasticity and spatial dependence of signal transduction pathways that promote protrusion in tandem with adhesion dynamics. We describe our modeling framework, as well as its abstraction, parameterization, and validation against experimental data. Analytical techniques for identifying and evaluating the effects of model bistability on simulation simulation results are shown, and implications of this analysis for understanding cell protrusion behavior are offered.
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Affiliation(s)
- Erik S Welf
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
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14
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Imaging the coordination of multiple signalling activities in living cells. Nat Rev Mol Cell Biol 2011; 12:749-56. [PMID: 22016058 DOI: 10.1038/nrm3212] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cellular signal transduction occurs in complex and redundant interaction networks, which are best understood by simultaneously monitoring the activation dynamics of multiple components. Recent advances in biosensor technology have made it possible to visualize and quantify the activation of multiple network nodes in the same living cell. The precision and scope of this approach has been greatly extended by novel computational approaches (referred to as computational multiplexing) that can reveal relationships between network nodes imaged in separate cells.
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15
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Welf ES, Haugh JM. Signaling pathways that control cell migration: models and analysis. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:231-40. [PMID: 21305705 DOI: 10.1002/wsbm.110] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Dissecting the intracellular signaling mechanisms that govern the movement of eukaryotic cells presents a major challenge, not only because of the large number of molecular players involved, but even more so because of the dynamic nature of their regulation by both biochemical and mechanical interactions. Computational modeling and analysis have emerged as useful tools for understanding how the physical properties of cells and their microenvironment are coupled with certain biochemical pathways to actuate and control cell motility. In this focused review, we highlight some of the more recent applications of quantitative modeling and analysis in the field of cell migration. Both in modeling and experiment, it has been prudent to follow a reductionist approach in order to characterize what are arguably the principal modules: spatial polarization of signaling pathways, regulation of the actin cytoskeleton, and dynamics of focal adhesions. While it is important that we 'cut our teeth' on these subsystems, focusing on the details of certain aspects while ignoring or coarse-graining others, it is clear that the challenge ahead will be to characterize the couplings between them in an integrated framework.
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Affiliation(s)
- Erik S Welf
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
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16
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Kiyokawa E, Aoki K, Nakamura T, Matsuda M. Spatiotemporal regulation of small GTPases as revealed by probes based on the principle of Förster Resonance Energy Transfer (FRET): Implications for signaling and pharmacology. Annu Rev Pharmacol Toxicol 2011; 51:337-58. [PMID: 20936947 DOI: 10.1146/annurev-pharmtox-010510-100234] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Low molecular weight ("small") GTPases are key regulators of a number of signaling cascades. Each GTPase is regulated by numerous guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and each GTPase binds to numerous effector proteins in a GTP-dependent manner. In many instances, individual regulators activate more than one GTPase, and each effector binds to one or more GTPases belonging to the same family. To untangle these complex networks, probes based on the principle of Förster resonance energy transfer (FRET) are widely used. Here, we provide an overview of the probes based on FRET and examples of discoveries achieved with them. In the process, we attempt to delineate the merits, current limitations, and future applications of this technique to pharmacological studies.
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Affiliation(s)
- Etsuko Kiyokawa
- Department of Pathology and Biology of Diseases, Kyoto University, Japan
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Xiong Y, Kabacoff C, Franca-Koh J, Devreotes PN, Robinson DN, Iglesias PA. Automated characterization of cell shape changes during amoeboid motility by skeletonization. BMC SYSTEMS BIOLOGY 2010; 4:33. [PMID: 20334652 PMCID: PMC2864235 DOI: 10.1186/1752-0509-4-33] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 03/24/2010] [Indexed: 01/14/2023]
Abstract
BACKGROUND The ability of a cell to change shape is crucial for the proper function of many cellular processes, including cell migration. One type of cell migration, referred to as amoeboid motility, involves alternating cycles of morphological expansion and retraction. Traditionally, this process has been characterized by a number of parameters providing global information about shape changes, which are insufficient to distinguish phenotypes based on local pseudopodial activities that typify amoeboid motility. RESULTS We developed a method that automatically detects and characterizes pseudopodial behavior of cells. The method uses skeletonization, a technique from morphological image processing to reduce a shape into a series of connected lines. It involves a series of automatic algorithms including image segmentation, boundary smoothing, skeletonization and branch pruning, and takes into account the cell shape changes between successive frames to detect protrusion and retraction activities. In addition, the activities are clustered into different groups, each representing the protruding and retracting history of an individual pseudopod. CONCLUSIONS We illustrate the algorithms on movies of chemotaxing Dictyostelium cells and show that our method makes it possible to capture the spatial and temporal dynamics as well as the stochastic features of the pseudopodial behavior. Thus, the method provides a powerful tool for investigating amoeboid motility.
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Affiliation(s)
- Yuan Xiong
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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Aoki K, Matsuda M. Visualization of small GTPase activity with fluorescence resonance energy transfer-based biosensors. Nat Protoc 2009; 4:1623-31. [DOI: 10.1038/nprot.2009.175] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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