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Kusumi A, Tsunoyama TA, Suzuki KGN, Fujiwara TK, Aladag A. Transient, nano-scale, liquid-like molecular assemblies coming of age. Curr Opin Cell Biol 2024; 89:102394. [PMID: 38963953 DOI: 10.1016/j.ceb.2024.102394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 06/02/2024] [Accepted: 06/06/2024] [Indexed: 07/06/2024]
Abstract
This review examines the dynamic mechanisms underlying cellular signaling, communication, and adhesion via transient, nano-scale, liquid-like molecular assemblies on the plasma membrane (PM). Traditional views posit that stable, solid-like molecular complexes perform these functions. However, advanced imaging reveals that many signaling and scaffolding proteins only briefly reside in these molecular complexes and that micron-scale protein assemblies on the PM, including cell adhesion structures and synapses, are likely made of archipelagoes of nanoliquid protein islands. Borrowing the concept of liquid-liquid phase separation to form micron-scale biocondensates, we propose that these nano-scale oligomers and assemblies are enabled by multiple weak but specific molecular interactions often involving intrinsically disordered regions. The signals from individual nanoliquid signaling complexes would occur as pulses. Single-molecule imaging emerges as a crucial technique for characterizing these transient nanoliquid assemblies on the PM, suggesting a shift toward a model where the fluidity of interactions underpins signal regulation and integration.
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Affiliation(s)
- Akihiro Kusumi
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan; Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan.
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan
| | - Kenichi G N Suzuki
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan; Institute for Glyco-core Research (iGCORE), Gifu University, Gifu 501-1193, Japan; National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Takahiro K Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Amine Aladag
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan; Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
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2
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Chen T, Giannone G. Single molecule imaging unveils cellular architecture, dynamics and mechanobiology. Curr Opin Cell Biol 2024; 88:102369. [PMID: 38759257 DOI: 10.1016/j.ceb.2024.102369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 05/19/2024]
Abstract
The biomechanical regulation of the cytoskeleton and cell adhesions underlies various essential cellular functions. Studying them requires visualizing their nanostructure and molecular dynamics with evermore precise spatio-temporal resolution. In this review we will focus on the recent advances in single molecule fluorescence imaging techniques and discuss how they improve our understanding of mechanically sensitive cellular structures such as adhesions and the cytoskeleton. We will also discuss future directions for research, emphasizing on the 3D nature of cellular structures and tissues, their mechanical regulation at the molecule level, as well as how super-resolution microscopy will enhance our knowledge on protein structure and conformational changes in the cellular context.
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Affiliation(s)
- Tianchi Chen
- Interdisciplinary Institute for Neuroscience, Université Bordeaux, CNRS, UMR 5297, 33000 Bordeaux, France
| | - Grégory Giannone
- Interdisciplinary Institute for Neuroscience, Université Bordeaux, CNRS, UMR 5297, 33000 Bordeaux, France.
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3
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Nunes Vicente F, Chen T, Rossier O, Giannone G. Novel imaging methods and force probes for molecular mechanobiology of cytoskeleton and adhesion. Trends Cell Biol 2023; 33:204-220. [PMID: 36055943 DOI: 10.1016/j.tcb.2022.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 12/01/2022]
Abstract
Detection and conversion of mechanical forces into biochemical signals is known as mechanotransduction. From cells to tissues, mechanotransduction regulates migration, proliferation, and differentiation in processes such as immune responses, development, and cancer progression. Mechanosensitive structures such as integrin adhesions, the actin cortex, ion channels, caveolae, and the nucleus sense and transmit forces. In vitro approaches showed that mechanosensing is based on force-dependent protein deformations and reorganizations. However, the mechanisms in cells remained unclear since cell imaging techniques lacked molecular resolution. Thanks to recent developments in super-resolution microscopy (SRM) and molecular force sensors, it is possible to obtain molecular insight of mechanosensing in live cells. We discuss how understanding of molecular mechanotransduction was revolutionized by these innovative approaches, focusing on integrin adhesions, actin structures, and the plasma membrane.
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Affiliation(s)
- Filipe Nunes Vicente
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Tianchi Chen
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Olivier Rossier
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Grégory Giannone
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
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Kanchanawong P, Calderwood DA. Organization, dynamics and mechanoregulation of integrin-mediated cell-ECM adhesions. Nat Rev Mol Cell Biol 2023; 24:142-161. [PMID: 36168065 PMCID: PMC9892292 DOI: 10.1038/s41580-022-00531-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2022] [Indexed: 02/04/2023]
Abstract
The ability of animal cells to sense, adhere to and remodel their local extracellular matrix (ECM) is central to control of cell shape, mechanical responsiveness, motility and signalling, and hence to development, tissue formation, wound healing and the immune response. Cell-ECM interactions occur at various specialized, multi-protein adhesion complexes that serve to physically link the ECM to the cytoskeleton and the intracellular signalling apparatus. This occurs predominantly via clustered transmembrane receptors of the integrin family. Here we review how the interplay of mechanical forces, biochemical signalling and molecular self-organization determines the composition, organization, mechanosensitivity and dynamics of these adhesions. Progress in the identification of core multi-protein modules within the adhesions and characterization of rearrangements of their components in response to force, together with advanced imaging approaches, has improved understanding of adhesion maturation and turnover and the relationships between adhesion structures and functions. Perturbations of adhesion contribute to a broad range of diseases and to age-related dysfunction, thus an improved understanding of their molecular nature may facilitate therapeutic intervention in these conditions.
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Affiliation(s)
- Pakorn Kanchanawong
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore.
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
| | - David A Calderwood
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA.
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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5
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Apte A, Manich M, Labruyère E, Datta S. PI Kinase-EhGEF2-EhRho5 axis contributes to LPA stimulated macropinocytosis in Entamoeba histolytica. PLoS Pathog 2022; 18:e1010550. [PMID: 35594320 PMCID: PMC9173640 DOI: 10.1371/journal.ppat.1010550] [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: 01/04/2022] [Revised: 06/07/2022] [Accepted: 04/26/2022] [Indexed: 12/04/2022] Open
Abstract
Entamoeba histolytica is a protozoan responsible for several pathologies in humans. Trophozoites breach the intestinal site to enter the bloodstream and thus traverse to a secondary site. Macropinocytosis and phagocytosis, collectively accounting for heterophagy, are the two major processes responsible for sustenance of Entamoeba histolytica within the host. Both of these processes require significant rearrangements in the structure to entrap the target. Rho GTPases play an indispensable role in mustering proteins that regulate cytoskeletal remodelling. Unlike phagocytosis which has been studied in extensive detail, information on machinery of macropinocytosis in E. histolytica is still limited. In the current study, using site directed mutagenesis and RNAi based silencing, coupled with functional studies, we have demonstrated the involvement of EhRho5 in constitutive and LPA stimulated macropinocytosis. We also report that LPA, a bioactive phospholipid present in the bloodstream of the host, activates EhRho5 and translocates it from cytosol to plasma membrane and endomembrane compartments. Using biochemical and FRAP studies, we established that a PI Kinase acts upstream of EhRho5 in LPA mediated signalling. We further identified EhGEF2 as a guanine nucleotide exchange factor of EhRho5. In the amoebic trophozoites, EhGEF2 depletion leads to reduced macropinocytic efficiency of trophozoites, thus phenocopying its substrate. Upon LPA stimulation, EhGEF2 is found to sequester near the plasma membrane in a wortmannin sensitive fashion, explaining a possible mode for activation of EhRho5 in the amoebic trophozoites. Collectively, we propose that LPA stimulated macropinocytosis in E. histolytica is driven by the PI Kinase-EhGEF2-EhRho5 axis. Entamoeba histolytica is an enteric parasite in humans, which leads to various pathologies like dysentery, diarrhoea and abscess formation. Host cells are known to secrete chemokines and growth factors, which are utilized by trophozoites for sustenance and pathogenesis. The sustenance of this parasite within the host requires nutrient uptake, which involves macropinocytosis and phagocytosis. However, the regulation of macropinocytosis is less explored in E. histolytica. We have established for the first time that constitutive as well as LPA stimulated macropinocytosis in amoebic trophozoites functions via PI Kinase-EhGEF2-EhRho5 axis. We also excavated the dynamicity and the spatio-temporal regulation of EhRho5 activity and the associated dynamics in the LPA stimulated cells.
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Affiliation(s)
- Achala Apte
- Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, India
| | - Maria Manich
- Bioimage Analysis Unit, Institut Pasteur, Paris, France
| | | | - Sunando Datta
- Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, India
- * E-mail:
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Single-Protein Tracking to Study Protein Interactions During Integrin-Based Migration. Methods Mol Biol 2021; 2217:85-113. [PMID: 33215379 DOI: 10.1007/978-1-0716-0962-0_8] [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: 12/03/2022]
Abstract
Cell migration is a complex biophysical process which involves the coordination of molecular assemblies including integrin-dependent adhesions, signaling networks and force-generating cytoskeletal structures incorporating both actin polymerization and myosin activity. During the last decades, proteomic studies have generated impressive protein-protein interaction maps, although the subcellular location, duration, strength, sequence, and nature of these interactions are still concealed. In this chapter we describe how recent developments in superresolution microscopy (SRM) and single-protein tracking (SPT) start to unravel protein interactions and actions in subcellular molecular assemblies driving cell migration.
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Lietha D, Izard T. Roles of Membrane Domains in Integrin-Mediated Cell Adhesion. Int J Mol Sci 2020; 21:ijms21155531. [PMID: 32752284 PMCID: PMC7432473 DOI: 10.3390/ijms21155531] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 12/13/2022] Open
Abstract
The composition and organization of the plasma membrane play important functional and regulatory roles in integrin signaling, which direct many physiological and pathological processes, such as development, wound healing, immunity, thrombosis, and cancer metastasis. Membranes are comprised of regions that are thick or thin owing to spontaneous partitioning of long-chain saturated lipids from short-chain polyunsaturated lipids into domains defined as ordered and liquid-disorder domains, respectively. Liquid-ordered domains are typically 100 nm in diameter and sometimes referred to as lipid rafts. We posit that integrin β senses membrane thickness and that mechanical force on the membrane regulates integrin activation through membrane thinning. This review examines what we know about the nature and mechanism of the interaction of integrins with the plasma membrane and its effects on regulating integrins and its binding partners.
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Affiliation(s)
- Daniel Lietha
- Cell Signaling and Adhesion Group, Structural and Chemical Biology, Margarita Salas Center for Biological Research (CIB-CSIC), E-28040 Madrid, Spain;
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
- Correspondence:
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8
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Shin EY, Park JH, You ST, Lee CS, Won SY, Park JJ, Kim HB, Shim J, Soung NK, Lee OJ, Schwartz MA, Kim EG. Integrin-mediated adhesions in regulation of cellular senescence. SCIENCE ADVANCES 2020; 6:eaay3909. [PMID: 32494696 PMCID: PMC7202880 DOI: 10.1126/sciadv.aay3909] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 02/21/2020] [Indexed: 05/10/2023]
Abstract
Bioinformatic and functional data link integrin-mediated cell adhesion to cellular senescence; however, the significance of and molecular mechanisms behind these connections are unknown. We now report that the focal adhesion-localized βPAK-interacting exchange factor (βPIX)-G protein-coupled receptor kinase interacting protein (GIT) complex controls cellular senescence in vitro and in vivo. βPIX and GIT levels decline with age. βPIX knockdown induces cellular senescence, which was prevented by reexpression. Loss of βPIX induced calpain cleavage of the endocytic adapter amphiphysin 1 to suppress clathrin-mediated endocytosis (CME); direct competition of GIT1/2 for the calpain-binding site on paxillin mediates this effect. Decreased CME and thus integrin endocytosis induced abnormal integrin signaling, with elevated reactive oxygen species production. Blocking integrin signaling inhibited senescence in human fibroblasts and mouse lungs in vivo. These results reveal a central role for integrin signaling in cellular senescence, potentially identifying a new therapeutic direction.
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Affiliation(s)
- Eun-Young Shin
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Jin-Hee Park
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Soon-Tae You
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Chan-Soo Lee
- Food Standard Division Scientific Office, Ministry of Food and Drug Safety (KFDA), Osong-eup, Cheongju 28159, Korea
| | - So-Yoon Won
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Jung-Jin Park
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Han-Byeol Kim
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Jaegal Shim
- Comparative Biomedicine Research Branch, Research Institute, National Cancer Center, Goyang 10408, Korea
| | - Nak-Kyun Soung
- World Class Institute, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Ochang-eup, Cheongju 28116, Korea
| | - Ok-Jun Lee
- Department of Pathology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Martin Alexander Schwartz
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine and Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06511, USA
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester, UK
- Corresponding author. (E.-G.K.); (M.A.S.)
| | - Eung-Gook Kim
- Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju 28644, Korea
- Corresponding author. (E.-G.K.); (M.A.S.)
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9
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Mehidi A, Rossier O, Schaks M, Chazeau A, Binamé F, Remorino A, Coppey M, Karatas Z, Sibarita JB, Rottner K, Moreau V, Giannone G. Transient Activations of Rac1 at the Lamellipodium Tip Trigger Membrane Protrusion. Curr Biol 2019; 29:2852-2866.e5. [DOI: 10.1016/j.cub.2019.07.035] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 04/25/2019] [Accepted: 07/11/2019] [Indexed: 01/22/2023]
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10
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Ge Y, Gao J, Jordan R, Naumann CA. Changes in Cholesterol Level Alter Integrin Sequestration in Raft-Mimicking Lipid Mixtures. Biophys J 2019; 114:158-167. [PMID: 29320683 DOI: 10.1016/j.bpj.2017.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 11/30/2022] Open
Abstract
The influence of cholesterol (CHOL) level on integrin sequestration in raft-mimicking lipid mixtures forming coexisting liquid-ordered (lo) and liquid-disordered (ld) lipid domains is investigated using complementary, single-molecule-sensitive, confocal detection methods. Systematic analysis of membrane protein distribution in such a model membrane environment demonstrates that variation of CHOL level has a profound influence on lo-ld sequestration of integrins, thereby exhibiting overall ld preference in the absence of ligands and lo affinity upon vitronectin addition. Accompanying photon-counting histogram analysis of integrins in the different model membrane mixtures shows that the observed changes of integrin sequestration in response to variations of membrane CHOL level are not associated with altering integrin oligomerization states. Instead, our experiments suggest that the strong CHOL dependence of integrin sequestration can be attributed to CHOL-mediated changes of lipid packing and bilayer thickness in coexisting lo and ld domains, highlighting the significance of a biophysical mechanism of CHOL-mediated regulation of integrin sequestration. We envision that this model membrane study may help clarify the influence of CHOL in integrin functionality in plasma membranes, thus providing further insight into the role of lipid heterogeneities in membrane protein distribution and function in a cellular membrane environment.
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Affiliation(s)
- Yifan Ge
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Jiayun Gao
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Rainer Jordan
- Makromolekulare Chemie, TU Dresden, Dresden, Germany
| | - Christoph A Naumann
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana; Integrated Nanosystems Development Institute, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana.
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11
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Rac1 Nanoscale Organization on the Plasma Membrane Is Driven by Lipid Binding Specificity Encoded in the Membrane Anchor. Mol Cell Biol 2018; 38:MCB.00186-18. [PMID: 29967243 DOI: 10.1128/mcb.00186-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/21/2018] [Indexed: 12/21/2022] Open
Abstract
Rac1 is a small guanine nucleotide binding protein that cycles between an inactive GDP-bound and active GTP-bound state to regulate cell motility and migration. Rac1 signaling is initiated from the plasma membrane (PM). Here, we used high-resolution spatial mapping and manipulation of PM lipid composition to define Rac1 nanoscale organization. We found that Rac1 proteins in the GTP- and GDP-bound states assemble into nonoverlapping nanoclusters; thus, Rac1 proteins undergo nucleotide-dependent segregation. Rac1 also selectively interacts with phosphatidic acid (PA) and phosphoinositol (3,4,5)-trisphosphate (PIP3), resulting in nanoclusters enriched in these lipids. These lipids are structurally important because depleting the PM of PA or PIP3 impairs both Rac1 PM binding and Rac1 nanoclustering. Lipid binding specificity of Rac1 is encoded in the amino acid sequence of the polybasic domain (PBD) of the C-terminal membrane anchor. Point mutations within the PBD, including arginine-to-lysine substitutions, profoundly alter Rac1 lipid binding specificity without changing the electrostatics of the protein and result in impaired macropinocytosis and decreased cell spreading. We propose that Rac1 nanoclusters act as lipid-based signaling platforms emulating the spatiotemporal organization of Ras proteins and show that the Rac1 PBD-prenyl anchor has a biological function that extends beyond simple electrostatic engagement with the PM.
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12
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Feng S, Zhou L, Zhang Y, Lü S, Long M. Mechanochemical modeling of neutrophil migration based on four signaling layers, integrin dynamics, and substrate stiffness. Biomech Model Mechanobiol 2018; 17:1611-1630. [PMID: 29968162 DOI: 10.1007/s10237-018-1047-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/24/2018] [Indexed: 01/09/2023]
Abstract
Directional neutrophil migration during human immune responses is a highly coordinated process regulated by both biochemical and biomechanical environments. In this paper, we developed an integrative mathematical model of neutrophil migration using a lattice Boltzmann-particle method built in-house to solve the moving boundary problem with spatiotemporal regulation of biochemical components. The mechanical features of the cell cortex are modeled by a series of spring-connected nodes representing discrete cell-substrate adhesive sites. The intracellular signaling cascades responsible for cytoskeletal remodeling [e.g., small GTPases, phosphoinositide-3-kinase (PI3K), and phosphatase and tensin homolog] are built based on our previous four-layered signaling model centered on the bidirectional molecular transport mechanism and implemented as reaction-diffusion equations. Focal adhesion dynamics are determined by force-dependent integrin-ligand binding kinetics and integrin recycling and are thus integrated with cell motion. Using numerical simulations, the model reproduces the major features of cell migration in response to uniform and gradient biochemical stimuli based on the quantitative spatiotemporal regulation of signaling molecules, which agree with experimental observations. The existence of multiple types of integrins with different binding kinetics could act as an adaptation mechanism for substrate stiffness. Moreover, cells can perform reversal, U-turn, or lock-on behaviors depending on the steepness of the reversal biochemical signals received. Finally, this model is also applied to predict the responses of mutants in which PTEN is overexpressed or disrupted.
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Affiliation(s)
- Shiliang Feng
- Center for Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Lüwen Zhou
- Center for Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Yan Zhang
- Center for Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Shouqin Lü
- Center for Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Mian Long
- Center for Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China.
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13
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Remorino A, De Beco S, Cayrac F, Di Federico F, Cornilleau G, Gautreau A, Parrini MC, Masson JB, Dahan M, Coppey M. Gradients of Rac1 Nanoclusters Support Spatial Patterns of Rac1 Signaling. Cell Rep 2018; 21:1922-1935. [PMID: 29141223 DOI: 10.1016/j.celrep.2017.10.069] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/18/2017] [Accepted: 10/18/2017] [Indexed: 01/03/2023] Open
Abstract
Rac1 is a small RhoGTPase switch that orchestrates actin branching in space and time and protrusion/retraction cycles of the lamellipodia at the cell front during mesenchymal migration. Biosensor imaging has revealed a graded concentration of active GTP-loaded Rac1 in protruding regions of the cell. Here, using single-molecule imaging and super-resolution microscopy, we show an additional supramolecular organization of Rac1. We find that Rac1 partitions and is immobilized into nanoclusters of 50-100 molecules each. These nanoclusters assemble because of the interaction of the polybasic tail of Rac1 with the phosphoinositide lipids PIP2 and PIP3. The additional interactions with GEFs and possibly GAPs, downstream effectors, and other partners are responsible for an enrichment of Rac1 nanoclusters in protruding regions of the cell. Our results show that subcellular patterns of Rac1 activity are supported by gradients of signaling nanodomains of heterogeneous molecular composition, which presumably act as discrete signaling platforms.
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Affiliation(s)
- Amanda Remorino
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Simon De Beco
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Fanny Cayrac
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Fahima Di Federico
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Gaetan Cornilleau
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Alexis Gautreau
- Ecole Polytechnique, Université Paris-Saclay, CNRS UMR7654, 91120 Palaiseau, France
| | - Maria Carla Parrini
- Institut Curie, Centre de Recherche, Paris Sciences Lettres, ART Group, Inserm U830, Paris 75005, France
| | - Jean-Baptiste Masson
- Decision and Bayesian Computation, Institut Pasteur, 25 Rue du Docteur Roux, Paris, 75015, France; Bioinformatics and Biostatistics Hub - C3BI, USR 3756 IP CNRS, Paris, France
| | - Maxime Dahan
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Mathieu Coppey
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France.
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14
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Abstract
To get a complete understanding of cell migration, it is critical to study its orchestration at the molecular level. Since the recent developments in single-molecule imaging, it is now possible to study molecular phenomena at the single-molecule level inside living cells. In this chapter, we describe how such approaches have been and can be used to decipher molecular mechanisms involved in cell migration.
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15
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Nanoscale mechanobiology of cell adhesions. Semin Cell Dev Biol 2017; 71:53-67. [PMID: 28754443 DOI: 10.1016/j.semcdb.2017.07.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/17/2017] [Accepted: 07/19/2017] [Indexed: 12/16/2022]
Abstract
Proper physiological functions of cells and tissues depend upon their abilities to sense, transduce, integrate, and generate mechanical and biochemical signals. Although such mechanobiological phenomena are widely observed, the molecular mechanisms driving these outcomes are still not fully understood. Cell adhesions formed by integrins and cadherins receptors are key structures that process diverse sources of signals to elicit complex mechanobiological responses. Since the nanoscale is the length scale at which molecules interact to relay force and information, the understanding of cell adhesions at the nanoscale level is important for grasping the inner logics of cellular decision making. Until recently, the study of the biological nanoscale has been restricted by available molecular and imaging tools. Fortunately, rapid technological advances have increasingly opened up the nanoscale realm to systematic investigations. In this review, we discuss current insights and key open questions regarding the nanoscale structure and function relationship of cell adhesions, focusing on recent progresses in characterizing their composition, spatial organization, and cytomechanical operation.
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Abstract
The central mechanism for the transmission of the prion protein misfolding is the structural conversion of the normal cellular prion protein to the pathogenic misfolded prion protein, by the interaction with misfolded prion protein. This process might be enhanced due to the homo-dimerization/oligomerization of normal prion protein. However, the behaviors of normal prion protein in the plasma membrane have remained largely unknown. Here, using single fluorescent-molecule imaging, we found that both prion protein and Thy1, a control glycosylphosphatidylinositol-anchored protein, exhibited very similar intermittent transient immobilizations lasting for a few seconds within an area of 24.2 and 3.5 nm in diameter in CHO-K1 and hippocampal neurons cultured for 1- and 2-weeks, respectively. Prion protein molecules were immobile during 72% of the time, approximately 1.4× more than Thy1, due to prion protein’s higher immobilization frequency. When mobile, prion protein diffused 1.7× slower than Thy1. Prion protein’s slower diffusion might be caused by its transient interaction with other prion protein molecules, whereas its brief immobilization might be due to temporary association with prion protein clusters. Prion protein molecules might be newly recruited to prion protein clusters all the time, and simultaneously, prion protein molecules in the cluster might be departing continuously. Such dynamic interactions of normal prion protein molecules would strongly enhance the spreading of misfolded prion protein.
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Di Rienzo C, Cardarelli F, Di Luca M, Beltram F, Gratton E. Diffusion Tensor Analysis by Two-Dimensional Pair Correlation of Fluorescence Fluctuations in Cells. Biophys J 2016; 111:841-851. [PMID: 27558727 PMCID: PMC5002073 DOI: 10.1016/j.bpj.2016.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 07/08/2016] [Accepted: 07/08/2016] [Indexed: 11/22/2022] Open
Abstract
In a living cell, the movement of biomolecules is highly regulated by the cellular organization into subcompartments that impose barriers to diffusion, can locally break the spatial isotropy, and ultimately guide these molecules to their targets. Despite the pivotal role of these processes, experimental tools to fully probe the complex connectivity (and accessibility) of the cell interior with adequate spatiotemporal resolution are still lacking. Here, we show how the heterogeneity of molecular dynamics and the location of barriers to molecular motion can be mapped in live cells by exploiting a two-dimensional (2D) extension of the pair correlation function (pCF) analysis. Starting from a time series of images collected for the same field of view, the resulting 2D pCF is calculated in the proximity of each point for each time delay and allows us to probe the spatial distribution of the molecules that started from a given pixel. This 2D pCF yields an accurate description of the preferential diffusive routes. Furthermore, we combine this analysis with the image-derived mean-square displacement approach and gain information on the average nanoscopic molecular displacements in different directions. Through these quantities, we build a fluorescence-fluctuation-based diffusion tensor that contains information on speed and directionality of the local dynamical processes. Contrary to classical fluorescence correlation spectroscopy and related methods, this combined approach can distinguish between isotropic and anisotropic local diffusion. We argue that the measurement of this iMSD tensor will contribute to advance our understanding of the role played by the intracellular environment in the regulation of molecular diffusion at the nanoscale.
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Affiliation(s)
- Carmine Di Rienzo
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro, Pisa, Italy; Center for Nanotechnology Innovation @NEST, Istituto Italiano di Technologia, Piazza San Silvestro, Pisa, Italy.
| | - Francesco Cardarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Technologia, Piazza San Silvestro, Pisa, Italy
| | - Mariagrazia Di Luca
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro, Pisa, Italy
| | - Fabio Beltram
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro, Pisa, Italy; Center for Nanotechnology Innovation @NEST, Istituto Italiano di Technologia, Piazza San Silvestro, Pisa, Italy
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California.
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Sergé A. The Molecular Architecture of Cell Adhesion: Dynamic Remodeling Revealed by Videonanoscopy. Front Cell Dev Biol 2016; 4:36. [PMID: 27200348 PMCID: PMC4854873 DOI: 10.3389/fcell.2016.00036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/18/2016] [Indexed: 12/20/2022] Open
Abstract
The plasma membrane delimits the cell, which is the basic unit of living organisms, and is also a privileged site for cell communication with the environment. Cell adhesion can occur through cell-cell and cell-matrix contacts. Adhesion proteins such as integrins and cadherins also constitute receptors for inside-out and outside-in signaling within proteolipidic platforms. Adhesion molecule targeting and stabilization relies on specific features such as preferential segregation by the sub-membrane cytoskeleton meshwork and within membrane proteolipidic microdomains. This review presents an overview of the recent insights brought by the latest developments in microscopy, to unravel the molecular remodeling occurring at cell contacts. The dynamic aspect of cell adhesion was recently highlighted by super-resolution videomicroscopy, also named videonanoscopy. By circumventing the diffraction limit of light, nanoscopy has allowed the monitoring of molecular localization and behavior at the single-molecule level, on fixed and living cells. Accessing molecular-resolution details such as quantitatively monitoring components entering and leaving cell contacts by lateral diffusion and reversible association has revealed an unexpected plasticity. Adhesion structures can be highly specialized, such as focal adhesion in motile cells, as well as immune and neuronal synapses. Spatiotemporal reorganization of adhesion molecules, receptors, and adaptors directly relates to structure/function modulation. Assembly of these supramolecular complexes is continuously balanced by dynamic events, remodeling adhesions on various timescales, notably by molecular conformation switches, lateral diffusion within the membrane and endo/exocytosis. Pathological alterations in cell adhesion are involved in cancer evolution, through cancer stem cell interaction with stromal niches, growth, extravasation, and metastasis.
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Affiliation(s)
- Arnauld Sergé
- Centre de Cancérologie de Marseille, Équipe "Interactions Leuco/Stromales", Institut Paoli-Calmettes, Institut National de la Santé et de la Recherche Médicale U1068, Centre National de la Recherche Scientifique UMR7258, Aix-Marseille Université UM105 Marseille, France
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19
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Abstract
Rho GTPases are crucial signaling molecules that regulate a plethora of biological functions. Traditional biochemical, cell biological, and genetic approaches have founded the basis of Rho GTPase biology. The development of biosensors then allowed measuring Rho GTPase activity with unprecedented spatio-temporal resolution. This revealed that Rho GTPase activity fluctuates on time and length scales of tens of seconds and micrometers, respectively. In this review, we describe Rho GTPase activity patterns observed in different cell systems. We then discuss the growing body of evidence that upstream regulators such as guanine nucleotide exchange factors and GTPase-activating proteins shape these patterns by precisely controlling the spatio-temporal flux of Rho GTPase activity. Finally, we comment on additional mechanisms that might feed into the regulation of these signaling patterns and on novel technologies required to dissect this spatio-temporal complexity.
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Affiliation(s)
| | - Olivier Pertz
- Department of Biomedicine, University of Basel, Basel, Switzerland; Institute of Cell Biology, University of Bern, Bern, Switzerland
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20
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Rossier O, Giannone G. The journey of integrins and partners in a complex interactions landscape studied by super-resolution microscopy and single protein tracking. Exp Cell Res 2016; 343:28-34. [DOI: 10.1016/j.yexcr.2015.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 11/05/2015] [Indexed: 10/24/2022]
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21
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Selective Labeling of Proteins on Living Cell Membranes Using Fluorescent Nanodiamond Probes. NANOMATERIALS 2016; 6:nano6040056. [PMID: 28335184 PMCID: PMC5302567 DOI: 10.3390/nano6040056] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/07/2016] [Accepted: 03/15/2016] [Indexed: 11/23/2022]
Abstract
The impeccable photostability of fluorescent nanodiamonds (FNDs) is an ideal property for use in fluorescence imaging of proteins in living cells. However, such an application requires highly specific labeling of the target proteins with FNDs. Furthermore, the surface of unmodified FNDs tends to adsorb biomolecules nonspecifically, which hinders the reliable targeting of proteins with FNDs. Here, we combined hyperbranched polyglycerol modification of FNDs with the β-lactamase-tag system to develop a strategy for selective imaging of the protein of interest in cells. The combination of these techniques enabled site-specific labeling of Interleukin-18 receptor alpha chain, a membrane receptor, with FNDs, which eventually enabled tracking of the diffusion trajectory of FND-labeled proteins on the membrane surface.
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22
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Fujiwara TK, Iwasawa K, Kalay Z, Tsunoyama TA, Watanabe Y, Umemura YM, Murakoshi H, Suzuki KGN, Nemoto YL, Morone N, Kusumi A. Confined diffusion of transmembrane proteins and lipids induced by the same actin meshwork lining the plasma membrane. Mol Biol Cell 2016; 27:1101-19. [PMID: 26864625 PMCID: PMC4814218 DOI: 10.1091/mbc.e15-04-0186] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 02/02/2016] [Indexed: 11/11/2022] Open
Abstract
Ultraspeed single-molecule tracking with <25-μs resolution and electron tomography show that transmembrane proteins and phospholipids in the plasma membrane hop among submicrometer compartments of the same size, probably delimited by the anchored-transmembrane-protein pickets lining the actin-based membrane-skeleton fence, once every 1–58 ms. The mechanisms by which the diffusion rate in the plasma membrane (PM) is regulated remain unresolved, despite their importance in spatially regulating the reaction rates in the PM. Proposed models include entrapment in nanoscale noncontiguous domains found in PtK2 cells, slow diffusion due to crowding, and actin-induced compartmentalization. Here, by applying single-particle tracking at high time resolutions, mainly to the PtK2-cell PM, we found confined diffusion plus hop movements (termed “hop diffusion”) for both a nonraft phospholipid and a transmembrane protein, transferrin receptor, and equal compartment sizes for these two molecules in all five of the cell lines used here (actual sizes were cell dependent), even after treatment with actin-modulating drugs. The cross-section size and the cytoplasmic domain size both affected the hop frequency. Electron tomography identified the actin-based membrane skeleton (MSK) located within 8.8 nm from the PM cytoplasmic surface of PtK2 cells and demonstrated that the MSK mesh size was the same as the compartment size for PM molecular diffusion. The extracellular matrix and extracellular domains of membrane proteins were not involved in hop diffusion. These results support a model of anchored TM-protein pickets lining actin-based MSK as a major mechanism for regulating diffusion.
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Affiliation(s)
- Takahiro K Fujiwara
- Center for Meso-Bio Single-Molecule Imaging, Institute for Integrated Cell-Material Sciences, Kyoto 606-8501, Japan
| | - Kokoro Iwasawa
- Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Ziya Kalay
- Institute for Integrated Cell-Material Sciences, Kyoto 606-8507, Japan
| | - Taka A Tsunoyama
- Institute for Integrated Cell-Material Sciences, Kyoto 606-8507, Japan
| | - Yusuke Watanabe
- Institute for Integrated Cell-Material Sciences, Kyoto 606-8507, Japan
| | - Yasuhiro M Umemura
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Hideji Murakoshi
- National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Kenichi G N Suzuki
- Institute for Integrated Cell-Material Sciences, Kyoto 606-8507, Japan Institute for Stem Cell Biology and Regenerative Medicine and National Centre for Biological Sciences, Bangalore 650056, India
| | - Yuri L Nemoto
- Institute for Integrated Cell-Material Sciences, Kyoto 606-8507, Japan
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Akihiro Kusumi
- Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan Institute for Integrated Cell-Material Sciences, Kyoto 606-8507, Japan Membrane Cooperativity Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0412, Japan
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23
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Hu S, Tee YH, Kabla A, Zaidel-Bar R, Bershadsky A, Hersen P. Structured illumination microscopy reveals focal adhesions are composed of linear subunits. Cytoskeleton (Hoboken) 2015; 72:235-45. [PMID: 26012525 DOI: 10.1002/cm.21223] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 04/14/2015] [Accepted: 05/08/2015] [Indexed: 12/25/2022]
Abstract
The ability to mechanically interact with the extracellular matrix is a fundamental feature of adherent eukaryotic cells. Cell-matrix adhesion in many cell types is mediated by protein complexes called focal adhesions (FAs). Recent progress in super resolution microscopy revealed FAs possess an internal organization, yet such methods do not enable observation of the formation and dynamics of their internal structure in living cells. Here, we combine structured illumination microscopy (SIM) with total internal reflection fluorescence microscopy (TIRF) to show that the proteins inside FA patches are distributed along elongated subunits, typically 300 ± 100 nm wide, separated by 400 ± 100 nm, and individually connected to actin cables. We further show that the formation and dynamics of these linear subunits are intimately linked to radial actin fiber formation and actomyosin contractility. We found FA growth to be the result of nucleation of new linear subunits and their coordinated elongation. Taken together, this study reveals that the basic units of mature focal adhesion are 300-nm-wide elongated, dynamic structures. We anticipate this ultrastructure to be relevant to investigation of the function of FAs and their behavior in response to mechanical stress.
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Affiliation(s)
- Shiqiong Hu
- The Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Yee-Han Tee
- The Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Alexandre Kabla
- The Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
- Engineering Department, Cambridge University, Trumpington Street, Cambridge, CB2 1PZ, UK
| | - Ronen Zaidel-Bar
- The Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Alexander Bershadsky
- The Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Pascal Hersen
- The Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
- Laboratoire Matière et Systèmes Complexes, UMR 7057 CNRS and Université Paris Diderot, 10 Rue Alice Domon et Léonie Duquet, Paris, 75013, France
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Single-molecule tracking of small GTPase Rac1 uncovers spatial regulation of membrane translocation and mechanism for polarized signaling. Proc Natl Acad Sci U S A 2015; 112:E267-76. [PMID: 25561548 DOI: 10.1073/pnas.1409667112] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Polarized Rac1 signaling is a hallmark of many cellular functions, including cell adhesion, motility, and cell division. The two steps of Rac1 activation are its translocation to the plasma membrane and the exchange of nucleotide from GDP to GTP. It is, however, unclear whether these two processes are regulated independent of each other and what their respective roles are in polarization of Rac1 signaling. We designed a single-particle tracking (SPT) method to quantitatively analyze the kinetics of Rac1 membrane translocation in living cells. We found that the rate of Rac1 translocation was significantly elevated in protrusions during cell spreading on collagen. Furthermore, combining FRET sensor imaging with SPT measurements in the same cell, the recruitment of Rac1 was found to be polarized to an extent similar to that of the nucleotide exchange process. Statistical analysis of single-molecule trajectories and optogenetic manipulation of membrane lipids revealed that Rac1 membrane translocation precedes nucleotide exchange, and is governed primarily by interactions with phospholipids, particularly PI(3,4,5)P3, instead of protein factors. Overall, the study highlights the significance of membrane translocation in spatial Rac1 signaling, which is in addition to the traditional view focusing primarily on GEF distribution and exchange reaction.
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25
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Chazeau A, Mehidi A, Nair D, Gautier JJ, Leduc C, Chamma I, Kage F, Kechkar A, Thoumine O, Rottner K, Choquet D, Gautreau A, Sibarita JB, Giannone G. Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion. EMBO J 2014; 33:2745-64. [PMID: 25293574 DOI: 10.15252/embj.201488837] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super-resolution imaging, we revealed the nanoscale organization and dynamics of branched F-actin regulators in spines. Branched F-actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger-like protrusions. This spatial segregation differs from lamellipodia where both branched F-actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin-like protein-2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F-actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free-diffusion on the membrane. Enhanced Rac1 activation and Shank3 over-expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F-actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity.
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Affiliation(s)
- Anaël Chazeau
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Amine Mehidi
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Deepak Nair
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Jérémie J Gautier
- CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France
| | - Cécile Leduc
- University Bordeaux, LP2N, Talence, France CNRS & Institut d'Optique, LP2N, Talence, France
| | - Ingrid Chamma
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Frieda Kage
- Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany
| | - Adel Kechkar
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Alexis Gautreau
- CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France
| | - Jean-Baptiste Sibarita
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Grégory Giannone
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
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Tracking single molecules at work in living cells. Nat Chem Biol 2014; 10:524-32. [PMID: 24937070 DOI: 10.1038/nchembio.1558] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 05/21/2014] [Indexed: 11/09/2022]
Abstract
Methods for imaging and tracking single molecules conjugated with fluorescent probes, called single-molecule tracking (SMT), are now providing researchers with the unprecedented ability to directly observe molecular behaviors and interactions in living cells. Current SMT methods are achieving almost the ultimate spatial precision and time resolution for tracking single molecules, determined by the currently available dyes. In cells, various molecular interactions and reactions occur as stochastic and probabilistic processes. SMT provides an ideal way to directly track these processes by observing individual molecules at work in living cells, leading to totally new views of the biochemical and molecular processes used by cells whether in signal transduction, gene regulation or formation and disintegration of macromolecular complexes. Here we review SMT methods, summarize the recent results obtained by SMT, including related superresolution microscopy data, and describe the special concerns when SMT applications are shifted from the in vitro paradigms to living cells.
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27
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Moissoglu K, Schwartz MA. Spatial and temporal control of Rho GTPase functions. CELLULAR LOGISTICS 2014; 4:e943618. [PMID: 25610718 PMCID: PMC4279778 DOI: 10.4161/21592780.2014.943618] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 07/02/2014] [Indexed: 11/19/2022]
Abstract
Rho family GTPases control almost every aspect of cell physiology and, since their discovery, a wealth of knowledge has accumulated about their biochemical regulation and function. However, each Rho GTPase distributes between multiple cellular compartments, even within the same cell, where they are controlled by multiple regulators and signal to multiple effectors. Thus, major questions about spatial and temporal aspects of regulation remain unanswered. In particular, what are the nano-scale dynamics for their activation, membrane targeting, diffusion, effector activation and GTPase inactivation? How do these mechanisms differ in the different cellular compartments where Rho GTPases function? Addressing these complex aspects of Rho GTPase biology will significantly advance our understanding of the spatial and temporal control of cellular functions.
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Affiliation(s)
- Konstadinos Moissoglu
- Laboratory of Cellular and Molecular Biology; Center for Cancer Research; National Cancer Institute; National Institutes of Health ; Bethesda, MD USA
| | - Martin Alexander Schwartz
- Yale Cardiovascular Research Center and Departments of Medicine (Cardiology); Cell Biology and Biomedical Engineering; Yale School of Medicine ; New Haven, CT USA
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28
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Hiramoto-Yamaki N, Tanaka KAK, Suzuki KGN, Hirosawa KM, Miyahara MSH, Kalay Z, Tanaka K, Kasai RS, Kusumi A, Fujiwara TK. Ultrafast diffusion of a fluorescent cholesterol analog in compartmentalized plasma membranes. Traffic 2014; 15:583-612. [PMID: 24506328 PMCID: PMC4265843 DOI: 10.1111/tra.12163] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 01/20/2023]
Abstract
Cholesterol distribution and dynamics in the plasma membrane (PM) are poorly understood. The recent development of Bodipy488-conjugated cholesterol molecule (Bdp-Chol) allowed us to study cholesterol behavior in the PM, using single fluorescent-molecule imaging. Surprisingly, in the intact PM, Bdp-Chol diffused at the fastest rate ever found for any molecules in the PM, with a median diffusion coefficient (D) of 3.4 µm2/second, which was ∼10 times greater than that of non-raft phospholipid molecules (0.33 µm2/second), despite Bdp-Chol's probable association with raft domains. Furthermore, Bdp-Chol exhibited no sign of entrapment in time scales longer than 0.5 milliseconds. In the blebbed PM, where actin filaments were largely depleted, Bdp-Chol and Cy3-conjugated dioleoylphosphatidylethanolamine (Cy3-DOPE) diffused at comparable Ds (medians = 5.8 and 6.2 µm2/second, respectively), indicating that the actin-based membrane skeleton reduces the D of Bdp-Chol only by a factor of ∼2 from that in the blebbed PM, whereas it reduces the D of Cy3-DOPE by a factor of ∼20. These results are consistent with the previously proposed model, in which the PM is compartmentalized by the actin-based membrane-skeleton fence and its associated transmembrane picket proteins for the macroscopic diffusion of all of the membrane molecules, and suggest that the probability of Bdp-Chol passing through the compartment boundaries, once it enters the boundary, is ∼10× greater than that of Cy3-DOPE. Since the compartment sizes are greater than those of the putative raft domains, we conclude that raft domains coexist with membrane-skeleton-induced compartments and are contained within them.
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Affiliation(s)
- Nao Hiramoto-Yamaki
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS) and Institute for Frontier Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
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